Modeling Mediterranean forest structure using airborne laser scanning data

NASA Astrophysics Data System (ADS)

Bottalico, Francesca; Chirici, Gherardo; Giannini, Raffaello; Mele, Salvatore; Mura, Matteo; Puxeddu, Michele; McRoberts, Ronald E.; Valbuena, Ruben; Travaglini, Davide

2017-05-01

The conservation of biological diversity is recognized as a fundamental component of sustainable development, and forests contribute greatly to its preservation. Structural complexity increases the potential biological diversity of a forest by creating multiple niches that can host a wide variety of species. To facilitate greater understanding of the contributions of forest structure to forest biological diversity, we modeled relationships between 14 forest structure variables and airborne laser scanning (ALS) data for two Italian study areas representing two common Mediterranean forests, conifer plantations and coppice oaks subjected to irregular intervals of unplanned and non-standard silvicultural interventions. The objectives were twofold: (i) to compare model prediction accuracies when using two types of ALS metrics, echo-based metrics and canopy height model (CHM)-based metrics, and (ii) to construct inferences in the form of confidence intervals for large area structural complexity parameters. Our results showed that the effects of the two study areas on accuracies were greater than the effects of the two types of ALS metrics. In particular, accuracies were less for the more complex study area in terms of species composition and forest structure. However, accuracies achieved using the echo-based metrics were only slightly greater than when using the CHM-based metrics, thus demonstrating that both options yield reliable and comparable results. Accuracies were greatest for dominant height (Hd) (R2 = 0.91; RMSE% = 8.2%) and mean height weighted by basal area (R2 = 0.83; RMSE% = 10.5%) when using the echo-based metrics, 99th percentile of the echo height distribution and interquantile distance. For the forested area, the generalized regression (GREG) estimate of mean Hd was similar to the simple random sampling (SRS) estimate, 15.5 m for GREG and 16.2 m SRS. Further, the GREG estimator with standard error of 0.10 m was considerable more precise than the SRS estimator with standard error of 0.69 m.

The chimpanzee nest quantified: morphology and ecology of arboreal sleeping platforms within the dry habitat site of Toro-Semliki Wildlife Reserve, Uganda.

PubMed

Samson, David R

2012-10-01

The nightly construction of a sleeping platform (SP) or "nest" is widely regarded as a universal behavior among great apes, yet SP structural morphology has been incompletely quantified to date. This is in part due to the inherent difficulties of gathering empirical data on arboreally sited SPs. I gathered quantitative structural data on SPs (n = 65) at the Toro-Semliki Wildlife Reserve from May to June 2008 and from August 2010 to January 2011. I measured SP length (semi-major axis length), width (semi-minor axis length), radii (length from the surface center to the rim edge 45° from the axis), depth (width of the concavity from the surface center to the parallel rim), and thickness (ventral center to the dorsal underside of the SP). SP complexity was defined with a scored index. SP complexity was found to be correlated with SP circumference, surface area, mass, proportion of soft leafy material to hard woody material, number of frame support branches used in its construction, and other measures that are argued to index "comfort." In addition, the height of the tree canopy above the SP was negatively correlated with SP complexity. Greater complexity (and therefore stability) is argued to maintain SP integrity, stability and restraint in the face of greater wind speeds, thereby reducing the probability of falls. Given the observation that males site SPs lower than females (Fruth and Hohmann, Ethology 94:113-126, 1994; Brownlow et al., Am J Primatol 55:49-55, 2001), and that SP diameters were greater for SPs sited low in the canopy at Semliki, it is inferred that more massive males benefit from lower climbing expenses and greater stability. These data support Baldwin and colleagues' (Primates 22:474-486, 1981) hypothesis that the principal advantage of SPs over open-branch sleeping sites is the greater stability required by large-bodied great apes.

Structural basis of respiratory syncytial virus neutralization by motavizumab

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLellan, Jason S.; Chen, Man; Kim, Albert

2010-04-13

Motavizumab is {approx}tenfold more potent than its predecessor, palivizumab (Synagis), the FDA-approved monoclonal antibody used to prevent respiratory syncytial virus (RSV) infection. The structure of motavizumab in complex with a 24-residue peptide corresponding to its epitope on the RSV fusion (F) glycoprotein reveals the structural basis for this greater potency. Modeling suggests that motavizumab recognizes a different quaternary configuration of the F glycoprotein than that observed in a homologous structure.

Tectonic stratification and seismicity of the accretionary prism of the Azerbaijani part of Greater Caucasus

NASA Astrophysics Data System (ADS)

Alizade, Akif; Kangarli, Talat; Aliyev, Fuad

2013-04-01

The Greater Caucasus has formed during last stage of the tectogenesis in a geodynamic condition of the lateral compression, peculiar to the zone pseudo-subduction interaction zone between Northern and Southern Caucasian continental microplates. Its present day structure formed as a result of horizontal movements of the different phases and sub-phases of Alpine tectogenesis (from late Cimmerian to Valakhian), and is generally regarded as zone where, along Zangi deformation, the insular arc formations of the Northern edge of South Caucasian microplate thrust under the Meso-Cenozoic substantial complex contained in the facials of marginal sea of Greater Caucasus. The last, in its turn, has been pushed beneath the North-Caucasus continental margin of the Scythian plate along Main Caucasus Thrust fault. Data collected from the territory of Azerbaijan and its' sector of the Caspian area stands for pseudo-subduction interaction of microplates which resulted in the tectonic stratification of the continental slope of Alpine formations, marginal sea and insular arc into different scale plates of south vergent combined into napping complexes. In the orogeny's present structure, tectonically stratified Alpine substantial complex of the marginal sea of Greater Caucasus bordered by Main Caucasus and Zangi thrusts, is represented by allochthonous south vergent accretionary prism in the front of first deformation with its' root buried under the southern border of Scythian plate. Allocated beneath mentioned prism, the autochthonous bedding is presented by Meso-Cenosoic complex of the Northern flank of the South-Caucasian miroplate, which is in its' turn crushed and lensed into southward shifted tectonic microplates gently overlapping the northern flank of Kura flexure along Ganykh-Ayrichay-Alyat thrust. Data of real-time GPS measurement of regional geodynamics indicates that pseudo-subduction of South Caucasian microplate under the North Caucasian microplate still continues during present stage of alpine tectogenesis. Among others, ongoing pseudo-subduction is indicated by data of regional seismicity which is irregularly distributed by depth (foci levels 2-6; 8-12; 17-22; 25-45 km). Horizontal and vertical seismic zoning is explained by Earth crust's block divisibility and tectonic stratification, within the structure of which the earthquake focuses are mainly confined to the crossing nodes of differently oriented ruptures, or to the planes of deep tectonic disruptions and lateral displacements along unstable contacts of the substantial complexes with various degree of competence. At present stage of tectogenesis, seismically most active are the structures of the northern flank of South Caucasian microplate, controlled by Ganyx-Ayrichay-Alyat deep thrust with "General Caucasus" spread in the west, and sub-meridian right-lateral strike slip zone of the Western Caspian fault in the east of Azerbaijani part of Greater Caucasus.

Complex Engineered Systems: A New Paradigm

NASA Astrophysics Data System (ADS)

Mina, Ali A.; Braha, Dan; Bar-Yam, Yaneer

Human history is often seen as an inexorable march towards greater complexity — in ideas, artifacts, social, political and economic systems, technology, and in the structure of life itself. While we do not have detailed knowledge of ancient times, it is reasonable to conclude that the average resident of New York City today faces a world of much greater complexity than the average denizen of Carthage or Tikal. A careful consideration of this change, however, suggests that most of it has occurred recently, and has been driven primarily by the emergence of technology as a force in human life. In the 4000 years separating the Indus Valley Civilization from 18th century Europe, human transportation evolved from the bullock cart to the hansom, and the methods of communication used by George Washington did not differ significantly from those used by Alexander or Rameses. The world has moved radically towards greater complexity in the last two centuries. We have moved from buggies and letter couriers to airplanes and the Internet — an increase in capacity, and through its diversity also in complexity, orders of magnitude greater than that accumulated through the rest of human history. In addition to creating iconic artifacts — the airplane, the car, the computer, the television, etc. — this change has had a profound effect on the scope of experience by creating massive, connected and multiultra- level systems — traffic networks, power grids, markets, multinational corporations — that defy analytical understanding and seem to have a life of their own. This is where complexity truly enters our lives.

A Receptor on Acid.

PubMed

Chen, Qiuyan; Tesmer, John J G

2017-01-26

Wacker et al. report the crystal structure of LSD in complex with one of its major targets in the brain, the 5-HT 2B receptor, the first such structure for any psychedelic drug. The results shed light on the molecular mechanisms underlying its ability to induce hallucinations with greater duration and potency than closely related compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

[Morphometric features of the structure of the central nucleus of the amygdala in men and women].

PubMed

Antyukhov, A D

2015-01-01

To identify the interhemispheric asymmetry in the structure of the central nucleus of the amygdala in men and women. Morphometric features of the structure of neurons of the central nucleus amygdala complex were studied in histological sections of the brain of 6 men and 6 women (24 hemispheres), aged 19 to 55 years, with no lifetime diagnosis of mental or neurological disease. The value of the profile fields of neurons of the central nucleus amygdala complex in the left and right hemispheres of the brain were investigated. In women, the average value of neurons in the left hemisphere was somewhat greater than in the right hemisphere, while in men this value was greater in the right hemisphere. The interhemispheric morphometric differences were not significant regardless of gender. In addition, the quantity of relevant fields of neurons in the central nucleus of the amygdala in women was significantly larger than that of men in both hemispheres. The authors attempted to associate the results obtained in the study with emotional perception in men and women.

Minireview: DNA Replication in Plant Mitochondria

PubMed Central

Cupp, John D.; Nielsen, Brent L.

2014-01-01

Higher plant mitochondrial genomes exhibit much greater structural complexity as compared to most other organisms. Unlike well-characterized metazoan mitochondrial DNA (mtDNA) replication, an understanding of the mechanism(s) and proteins involved in plant mtDNA replication remains unclear. Several plant mtDNA replication proteins, including DNA polymerases, DNA primase/helicase, and accessory proteins have been identified. Mitochondrial dynamics, genome structure, and the complexity of dual-targeted and dual-function proteins that provide at least partial redundancy suggest that plants have a unique model for maintaining and replicating mtDNA when compared to the replication mechanism utilized by most metazoan organisms. PMID:24681310

Solid-state acid-base interactions in complexes of heterocyclic bases with dicarboxylic acids: crystallography, hydrogen bond analysis, and 15N NMR spectroscopy.

PubMed

Li, Z Jane; Abramov, Yuriy; Bordner, Jon; Leonard, Jason; Medek, Ales; Trask, Andrew V

2006-06-28

A cancer candidate, compound 1, is a weak base with two heterocyclic basic nitrogens and five hydrogen-bonding functional groups, and is sparingly soluble in water rendering it unsuitable for pharmaceutical development. The crystalline acid-base pairs of 1, collectively termed solid acid-base complexes, provide significant increases in the solubility and bioavailability compared to the free base, 1. Three dicarboxylic acid-base complexes, sesquisuccinate 2, dimalonate 3, and dimaleate 4, show the most favorable physicochemical profiles and are studied in greater detail. The structural analyses of the three complexes using crystal structure and solid-state NMR reveal that the proton-transfer behavior in these organic acid-base complexes vary successively correlating with Delta pKa. As a result, 2 is a neutral complex, 3 is a mixed ionic and zwitterionic complex and 4 is an ionic salt. The addition of the acidic components leads to maximized hydrogen bond interactions forming extended three-dimensional networks. Although structurally similar, the packing arrangements of the three complexes are considerably different due to the presence of multiple functional groups and the flexible backbone of 1. The findings in this study provide insight into the structural characteristics of complexes involving heterocyclic bases and carboxylic acids, and demonstrate that X-ray crystallography and 15N solid-state NMR are truly complementary in elucidating hydrogen bonding interactions and the degree of proton transfer of these complexes.

Crystal structure of checkpoint kinase 2 in complex with NSC 109555, a potent and selective inhibitor

PubMed Central

Lountos, George T; Tropea, Joseph E; Zhang, Di; Jobson, Andrew G; Pommier, Yves; Shoemaker, Robert H; Waugh, David S

2009-01-01

Checkpoint kinase 2 (Chk2), a ser/thr kinase involved in the ATM-Chk2 checkpoint pathway, is activated by genomic instability and DNA damage and results in either arrest of the cell cycle to allow DNA repair to occur or apoptosis if the DNA damage is severe. Drugs that specifically target Chk2 could be beneficial when administered in combination with current DNA-damaging agents used in cancer therapy. Recently, a novel inhibitor of Chk2, NSC 109555, was identified that exhibited high potency (IC50 = 240 nM) and selectivity. This compound represents a new chemotype and lead for the development of novel Chk2 inhibitors that could be used as therapeutic agents for the treatment of cancer. To facilitate the discovery of new analogs of NSC 109555 with even greater potency and selectivity, we have solved the crystal structure of this inhibitor in complex with the catalytic domain of Chk2. The structure confirms that the compound is an ATP-competitive inhibitor, as the electron density clearly reveals that it occupies the ATP-binding pocket. However, the mode of inhibition differs from that of the previously studied structure of Chk2 in complex with debromohymenialdisine, a compound that inhibits both Chk1 and Chk2. A unique hydrophobic pocket in Chk2, located very close to the bound inhibitor, presents an opportunity for the rational design of compounds with higher binding affinity and greater selectivity. PMID:19177354

A FUNCTIONAL NEUROIMAGING INVESTIGATION OF THE ROLES OF STRUCTURAL COMPLEXITY AND TASK-DEMAND DURING AUDITORY SENTENCE PROCESSING

PubMed Central

Love, Tracy; Haist, Frank; Nicol, Janet; Swinney, David

2009-01-01

Using functional magnetic resonance imaging (fMRI), this study directly examined an issue that bridges the potential language processing and multi-modal views of the role of Broca’s area: the effects of task-demands in language comprehension studies. We presented syntactically simple and complex sentences for auditory comprehension under three different (differentially complex) task-demand conditions: passive listening, probe verification, and theme judgment. Contrary to many language imaging findings, we found that both simple and complex syntactic structures activated left inferior frontal cortex (L-IFC). Critically, we found activation in these frontal regions increased together with increased task-demands. Specifically, tasks that required greater manipulation and comparison of linguistic material recruited L-IFC more strongly; independent of syntactic structure complexity. We argue that much of the presumed syntactic effects previously found in sentence imaging studies of L-IFC may, among other things, reflect the tasks employed in these studies and that L-IFC is a region underlying mnemonic and other integrative functions, on which much language processing may rely. PMID:16881268

Structural determinants of enzyme binding affinity: the E1 component of pyruvate dehydrogenase from Escherichia coli in complex with the inhibitor thiamin thiazolone diphosphate.

PubMed

Arjunan, Palaniappa; Chandrasekhar, Krishnamoorthy; Sax, Martin; Brunskill, Andrew; Nemeria, Natalia; Jordan, Frank; Furey, William

2004-03-09

Thiamin thiazolone diphosphate (ThTDP), a potent inhibitor of the E1 component from the Escherichia coli pyruvate dehydrogenase multienzyme complex (PDHc), binds to the enzyme with greater affinity than does the cofactor thiamin diphosphate (ThDP). To identify what determines this difference, the crystal structure of the apo PDHc E1 component complex with ThTDP and Mg(2+) has been determined at 2.1 A and compared to the known structure of the native holoenzyme, PDHc E1-ThDP-Mg(2+) complex. When ThTDP replaces ThDP, reorganization occurs in the protein structure in the vicinity of the active site involving positional and conformational changes in some amino acid residues, a change in the V coenzyme conformation, addition of new hydration sites, and elimination of others. These changes culminate in an increase in the number of hydrogen bonds to the protein, explaining the greater affinity of the apoenzyme for ThTDP. The observed hydrogen bonding pattern is not an invariant feature of ThDP-dependent enzymes but rather specific to this enzyme since the extra hydrogen bonds are made with nonconserved residues. Accordingly, these sequence-related hydrogen bonding differences likewise explain the wide variation in the affinities of different thiamin-dependent enzymes for ThTDP and ThDP. The sequence of each enzyme determines its ability to form hydrogen bonds to the inhibitor or cofactor. Mechanistic roles are suggested for the aforementioned reorganization and its reversal in PDHc E1 catalysis: to promote substrate binding and product release. This study also provides additional insight into the role of water in enzyme inhibition and catalysis.

Accurate Damage Location in Complex Composite Structures and Industrial Environments using Acoustic Emission

NASA Astrophysics Data System (ADS)

Eaton, M.; Pearson, M.; Lee, W.; Pullin, R.

2015-07-01

The ability to accurately locate damage in any given structure is a highly desirable attribute for an effective structural health monitoring system and could help to reduce operating costs and improve safety. This becomes a far greater challenge in complex geometries and materials, such as modern composite airframes. The poor translation of promising laboratory based SHM demonstrators to industrial environments forms a barrier to commercial up take of technology. The acoustic emission (AE) technique is a passive NDT method that detects elastic stress waves released by the growth of damage. It offers very sensitive damage detection, using a sparse array of sensors to detect and globally locate damage within a structure. However its application to complex structures commonly yields poor accuracy due to anisotropic wave propagation and the interruption of wave propagation by structural features such as holes and thickness changes. This work adopts an empirical mapping technique for AE location, known as Delta T Mapping, which uses experimental training data to account for such structural complexities. The technique is applied to a complex geometry composite aerospace structure undergoing certification testing. The component consists of a carbon fibre composite tube with varying wall thickness and multiple holes, that was loaded under bending. The damage location was validated using X-ray CT scanning and the Delta T Mapping technique was shown to improve location accuracy when compared with commercial algorithms. The onset and progression of damage were monitored throughout the test and used to inform future design iterations.

Nonlinear optical and G-Quadruplex DNA stabilization properties of novel mixed ligand copper(II) complexes and coordination polymers: Synthesis, structural characterization and computational studies

NASA Astrophysics Data System (ADS)

Rajasekhar, Bathula; Bodavarapu, Navya; Sridevi, M.; Thamizhselvi, G.; RizhaNazar, K.; Padmanaban, R.; Swu, Toka

2018-03-01

The present study reports the synthesis and evaluation of nonlinear optical property and G-Quadruplex DNA Stabilization of five novel copper(II) mixed ligand complexes. They were synthesized from copper(II) salt, 2,5- and 2,3- pyridinedicarboxylic acid, diethylenetriamine and amide based ligand (AL). The crystal structure of these complexes were determined through X-ray diffraction and supported by ESI-MAS, NMR, UV-Vis and FT-IR spectroscopic methods. Their nonlinear optical property was studied using Gaussian09 computer program. For structural optimization and nonlinear optical property, density functional theory (DFT) based B3LYP method was used with LANL2DZ basis set for metal ion and 6-31G∗ for C,H,N,O and Cl atoms. The present work reveals that pre-polarized Complex-2 showed higher β value (29.59 × 10-30e.s.u) as compared to that of neutral complex-1 (β = 0.276 × 10-30e.s.u.) which may be due to greater advantage of polarizability. Complex-2 is expected to be a potential material for optoelectronic and photonic technologies. Docking studies using AutodockVina revealed that complex-2 has higher binding energy for both G-Quadruplex DNA (-8.7 kcal/mol) and duplex DNA (-10.1 kcal/mol). It was also observed that structure plays an important role in binding efficiency.

Taking advantage of local structure descriptors to analyze interresidue contacts in protein structures and protein complexes.

PubMed

Martin, Juliette; Regad, Leslie; Etchebest, Catherine; Camproux, Anne-Claude

2008-11-15

Interresidue protein contacts in proteins structures and at protein-protein interface are classically described by the amino acid types of interacting residues and the local structural context of the contact, if any, is described using secondary structures. In this study, we present an alternate analysis of interresidue contact using local structures defined by the structural alphabet introduced by Camproux et al. This structural alphabet allows to describe a 3D structure as a sequence of prototype fragments called structural letters, of 27 different types. Each residue can then be assigned to a particular local structure, even in loop regions. The analysis of interresidue contacts within protein structures defined using Voronoï tessellations reveals that pairwise contact specificity is greater in terms of structural letters than amino acids. Using a simple heuristic based on specificity score comparison, we find that 74% of the long-range contacts within protein structures are better described using structural letters than amino acid types. The investigation is extended to a set of protein-protein complexes, showing that the similar global rules apply as for intraprotein contacts, with 64% of the interprotein contacts best described by local structures. We then present an evaluation of pairing functions integrating structural letters to decoy scoring and show that some complexes could benefit from the use of structural letter-based pairing functions.

High-Resolution Printing of 3D Structures Using an Electrohydrodynamic Inkjet with Multiple Functional Inks.

PubMed

An, Byeong Wan; Kim, Kukjoo; Lee, Heejoo; Kim, So-Yun; Shim, Yulhui; Lee, Dae-Young; Song, Jun Yeob; Park, Jang-Ung

2015-08-05

Electrohydrodynamic-inkjet-printed high-resolution complex 3D structures with multiple functional inks are demonstrated. Printed 3D structures can have a variety of fine patterns, such as vertical or helix-shaped pillars and straight or rounded walls, with high aspect ratios (greater than ≈50) and narrow diameters (≈0.7 μm). Furthermore, the formation of freestanding, bridge-like Ag wire structures on plastic substrates suggests substantial potentials as high-precision, flexible 3D interconnects. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of Commercial Structure-From Photogrammety Software Used for Underwater Three-Dimensional Modeling of Coral Reef Environments

NASA Astrophysics Data System (ADS)

Burns, J. H. R.; Delparte, D.

2017-02-01

Structural complexity in ecosystems creates an assortment of microhabitat types and has been shown to support greater diversity and abundance of associated organisms. The 3D structure of an environment also directly affects important ecological parameters such as habitat provisioning and light availability and can therefore strongly influence ecosystem function. Coral reefs are architecturally complex 3D habitats, whose structure is intrinsically linked to the ecosystem biodiversity, productivity, and function. The field of coral ecology has, however, been primarily limited to using 2-dimensional (2D) planar survey techniques for studying the physical structure of reefs. This conventional approach fails to capture or quantify the intricate structural complexity of corals that influences habitat facilitation and biodiversity. A 3-dimensional (3D) approach can obtain accurate measurements of architectural complexity, topography, rugosity, volume, and other structural characteristics that affect biodiversity and abundance of reef organisms. Structurefrom- Motion (SfM) photogrammetry is an emerging computer vision technology that provides a simple and cost-effective method for 3D reconstruction of natural environments. SfM has been used in several studies to investigate the relationship between habitat complexity and ecological processes in coral reef ecosystems. This study compared two commercial SfM software packages, Agisoft Photoscan Pro and Pix4Dmapper Pro 3.1, in order to assess the cpaability and spatial accuracy of these programs for conducting 3D modeling of coral reef habitats at three spatial scales.

The interplay between habitat structure and chemical contaminants on biotic responses of benthic organisms

PubMed Central

Matias, Miguel G.; Coleman, Ross A.

2016-01-01

Habitat structure influences the diversity and distribution of organisms, potentially affecting their response to disturbances by either affecting their ‘susceptibility’ or through the provision of resources that can mitigate impacts of disturbances. Chemical disturbances due to contamination are associated with decreases in diversity and functioning of systems and are also likely to increase due to coastal urbanisation. Understanding how habitat structure interacts with contaminants is essential to predict and therefore manage such effects, minimising their consequences to marine systems. Here, we manipulated two structurally different habitats and exposed them to different types of contaminants. The effects of contamination and habitat structure interacted, affecting species richness. More complex experimental habitats were colonized by a greater diversity of organisms than the less complex habitats. These differences disappeared, however, when habitats were exposed to contaminants, suggesting that contaminants can override effects of habitats structure at small spatial scales. These results provide insight into the complex ways that habitat structure and contamination interact and the need to incorporate evidence of biotic responses from individual disturbances to multiple stressors. Such effects need to be taken into account when designing and planning management and conservation strategies to natural systems. PMID:27168991

Synthesis, crystal structure and biological activity of the Schiff base organotin(IV) complexes based on salicylaldehyde-o-aminophenol

NASA Astrophysics Data System (ADS)

Tan, Yu-Xing; Zhang, Zhi-Jian; Liu, Yang; Yu, Jiang-Xi; Zhu, Xiao-Ming; Kuang, Dai-Zhi; Jiang, Wu-Jiu

2017-12-01

Schiff base organotin(IV) complexes C1 ∼ C5b have been synthesized via the reaction of the substituted salicylaldehyde-o-aminophenol Schiff base ligands (L1 ∼ L3) with the dibenzyltin dichloride, n-butyltin trichloride or dibutyltin oxide, respectively. The complexes have been characterized by IR, UV-Vis, 1H NMR, 13C NMR spectra, elemental analysis and the crystal structures have been determined by X-ray diffraction. The anticancer activity of the Schiff base ligand and complexes C1 ∼ C5b against five species of cancer cell which are Hela, MCF7, HepG2, Colo205, NCIsbnd H460 were tested respectively, the tests showed that C1 ∼ C5b exhibited significant anticancer activity for the cancer cells in comparison with the ligand, and the activity was greater than carboplatin.

Modeling of the structure-specific kinetics of abiotic, dark reduction of Hg(II) complexed by O/N and S functional groups in humic acids while accounting for time-dependent structural rearrangement

USDA-ARS?s Scientific Manuscript database

Redox transformations involving electron transfer from natural organic matter (NOM) are important for the mercury (Hg) biogeochemical cycle. In the water column light drives the reduction of Hg(II) to Hg(0), whereas in soils and sediments dark reduction of Hg(II) is of greater importance. The object...

Natural shorelines promote the stability of fish communities in an urbanized coastal system.

PubMed

Scyphers, Steven B; Gouhier, Tarik C; Grabowski, Jonathan H; Beck, Michael W; Mareska, John; Powers, Sean P

2015-01-01

Habitat loss and fragmentation are leading causes of species extinctions in terrestrial, aquatic and marine systems. Along coastlines, natural habitats support high biodiversity and valuable ecosystem services but are often replaced with engineered structures for coastal protection or erosion control. We coupled high-resolution shoreline condition data with an eleven-year time series of fish community structure to examine how coastal protection structures impact community stability. Our analyses revealed that the most stable fish communities were nearest natural shorelines. Structurally complex engineered shorelines appeared to promote greater stability than simpler alternatives as communities nearest vertical walls, which are among the most prevalent structures, were most dissimilar from natural shorelines and had the lowest stability. We conclude that conserving and restoring natural habitats is essential for promoting ecological stability. However, in scenarios when natural habitats are not viable, engineered landscapes designed to mimic the complexity of natural habitats may provide similar ecological functions.

Natural Shorelines Promote the Stability of Fish Communities in an Urbanized Coastal System

PubMed Central

Scyphers, Steven B.; Gouhier, Tarik C.; Grabowski, Jonathan H.; Beck, Michael W.; Mareska, John; Powers, Sean P.

2015-01-01

Habitat loss and fragmentation are leading causes of species extinctions in terrestrial, aquatic and marine systems. Along coastlines, natural habitats support high biodiversity and valuable ecosystem services but are often replaced with engineered structures for coastal protection or erosion control. We coupled high-resolution shoreline condition data with an eleven-year time series of fish community structure to examine how coastal protection structures impact community stability. Our analyses revealed that the most stable fish communities were nearest natural shorelines. Structurally complex engineered shorelines appeared to promote greater stability than simpler alternatives as communities nearest vertical walls, which are among the most prevalent structures, were most dissimilar from natural shorelines and had the lowest stability. We conclude that conserving and restoring natural habitats is essential for promoting ecological stability. However, in scenarios when natural habitats are not viable, engineered landscapes designed to mimic the complexity of natural habitats may provide similar ecological functions. PMID:26039407

Differential numbers of foci of lymphocytes within the brains of Lewis rats exposed to weak complex nocturnal magnetic fields during development of experimental allergic encephalomyelitis.

PubMed

Persinger, Michael A

2009-01-01

To discern if specific structures of the rat brain contained more foci of lymphocytes following induction of experimental allergic encephalomyelitis and exposures to weak, amplitude-modulated magnetic fields for 6 min once per hour during the scotophase, the residuals between the observed and predicted values for the numbers of foci for 320 structures were obtained. Compared to the brains of sham-field exposed rats, the brains of rats exposed to 7-Hz 50 nT (0.5 mG) amplitude-modulated fields showed more foci within hippocampal structures and the dorsal central grey of the midbrain while those exposed to 7-Hz 500 nT (5 mG) fields showed greater densities within the hypothalamus and optic chiasm. The brains of rats exposed to either the 50 nT or 500 nT amplitude-modulated 40-Hz fields displayed greater densities of foci within the midbrain structures related to rapid eye movement. Most of the enhancements of infiltrations within the magnetic field-exposed rats occurred in structures within periventricular or periaqueductal regions and were both frequency- and intensity-dependent. The specificity and complexity of the configurations of the residuals of the numbers of infiltrated foci following exposures to the different fields suggest that the brain itself may be a "sensory organ" for the detection of these stimuli.

Hot spring microbial community composition, morphology, and carbon fixation: implications for interpreting the ancient rock record

NASA Astrophysics Data System (ADS)

Schuler, Caleb G.; Havig, Jeff R.; Hamilton, Trinity L.

2017-11-01

Microbial communities in hydrothermal systems exist in a range of macroscopic morphologies including stromatolites, mats, and filaments. The architects of these structures are typically autotrophic, serving as primary producers. Structures attributed to microbial life have been documented in the rock record dating back to the Archean including recent reports of microbially-related structures in terrestrial hot springs that date back as far as 3.5 Ga. Microbial structures exhibit a range of complexity from filaments to more complex mats and stromatolites and the complexity impacts preservation potential. As a result, interpretation of these structures in the rock record relies on isotopic signatures in combination with overall morphology and paleoenvironmental setting. However, the relationships between morphology, microbial community composition, and primary productivity remain poorly constrained. To begin to address this gap, we examined community composition and carbon fixation in filaments, mats, and stromatolites from the Greater Obsidian Pool Area (GOPA) of the Mud Volcano Area, Yellowstone National Park, WY. We targeted morphologies dominated by bacterial phototrophs located in close proximity within the same pool which are exposed to similar geochemistry as well as bacterial mat, algal filament and chemotrophic filaments from nearby springs. Our results indicate i) natural abundance δ13C values of biomass from these features (-11.0 to -24.3 ‰) are similar to those found in the rock record; ii) carbon uptake rates of photoautotrophic communities is greater than chemoautotrophic; iii) oxygenic photosynthesis, anoxygenic photosynthesis, and chemoautotrophy often contribute to carbon fixation within the same morphology; and iv) increasing phototrophic biofilm complexity corresponds to a significant decrease in rates of carbon fixation—filaments had the highest uptake rates whereas carbon fixation by stromatolites was significantly lower. Our data highlight important differences in primary productivity between structures despite indistinguishable δ13C values of the biomass. Furthermore, low primary productivity by stromatolites compared to other structures underscores the need to consider a larger role for microbial mats and filaments in carbon fixation and O2 generation during the Archean and Proterozoic.

Prions: Introducing a Complex Scientific Controversy to a Biology Classroom

ERIC Educational Resources Information Center

Zaitsev, Igor V.

2009-01-01

Thomas Kuhn, in "The Structure of Scientific Revolutions," posited that science does not progress by the steady accumulation of knowledge, but rather by a system of competition among paradigms. They vie for supremacy through greater parsimony, explanatory power, and popularity among the community of scientists (Kuhn, 1962). The current…

Tree structure and cavity microclimate: implications for bats and birds.

PubMed

Clement, Matthew J; Castleberry, Steven B

2013-05-01

It is widely assumed that tree cavity structure and microclimate affect cavity selection and use in cavity-dwelling bats and birds. Despite the interest in tree structure and microclimate, the relationship between the two has rarely been quantified. Currently available data often comes from artificial structures that may not accurately represent conditions in natural cavities. We collected data on tree cavity structure and microclimate from 45 trees in five cypress-gum swamps in the Coastal Plain of Georgia in the United States in 2008. We used hierarchical linear models to predict cavity microclimate from tree structure and ambient temperature and humidity, and used Aikaike's information criterion to select the most parsimonious models. We found large differences in microclimate among trees, but tree structure variables explained <28% of the variation, while ambient conditions explained >80% of variation common to all trees. We argue that the determinants of microclimate are complex and multidimensional, and therefore cavity microclimate cannot be deduced easily from simple tree structures. Furthermore, we found that daily fluctuations in ambient conditions strongly affect microclimate, indicating that greater weather fluctuations will cause greater differences among tree cavities.

Spatial Patterns in Herbivory on a Coral Reef Are Influenced by Structural Complexity but Not by Algal Traits

PubMed Central

Vergés, Adriana; Vanderklift, Mathew A.; Doropoulos, Christopher; Hyndes, Glenn A.

2011-01-01

Background Patterns of herbivory can alter the spatial structure of ecosystems, with important consequences for ecosystem functions and biodiversity. While the factors that drive spatial patterns in herbivory in terrestrial systems are well established, comparatively less is known about what influences the distribution of herbivory in coral reefs. Methodology and Principal Findings We quantified spatial patterns of macroalgal consumption in a cross-section of Ningaloo Reef (Western Australia). We used a combination of descriptive and experimental approaches to assess the influence of multiple macroalgal traits and structural complexity in establishing the observed spatial patterns in macroalgal herbivory, and to identify potential feedback mechanisms between herbivory and macroalgal nutritional quality. Spatial patterns in macroalgal consumption were best explained by differences in structural complexity among habitats. The biomass of herbivorous fish, and rates of herbivory were always greater in the structurally-complex coral-dominated outer reef and reef flat habitats, which were also characterised by high biomass of herbivorous fish, low cover and biomass of macroalgae and the presence of unpalatable algae species. Macroalgal consumption decreased to undetectable levels within 75 m of structurally-complex reef habitat, and algae were most abundant in the structurally-simple lagoon habitats, which were also characterised by the presence of the most palatable algae species. In contrast to terrestrial ecosystems, herbivory patterns were not influenced by the distribution, productivity or nutritional quality of resources (macroalgae), and we found no evidence of a positive feedback between macroalgal consumption and the nitrogen content of algae. Significance This study highlights the importance of seascape-scale patterns in structural complexity in determining spatial patterns of macroalgal consumption by fish. Given the importance of herbivory in maintaining the ability of coral reefs to reorganise and retain ecosystem functions following disturbance, structural complexity emerges as a critical feature that is essential for the healthy functioning of these ecosystems. PMID:21347254

Effects of structural complexity on within-canopy light environments and leaf traits in a northern mixed deciduous forest

NASA Astrophysics Data System (ADS)

Fotis, A. T.; Curtis, P.

2016-12-01

Canopy structure influences forest productivity through its effects on the distribution of radiation and the light-induced changes in leaf physiological traits. Due to the difficulty of accessing and measuring forest canopies, few field-based studies have quantitatively linked these divergent scales of canopy functioning. The objective of our study was to investigate how canopy structure affects light profiles within a forest canopy and whether leaves of mature trees adjust morphologically and biochemically to the light environments characteristic of canopies with different structural complexity. We used a combination of light detection and ranging (LiDAR) data and hemispherical photographs to quantify canopy structure and light environments, respectively, and a telescoping pole to sample leaves. Leaf mass per area (LMA), nitrogen on an area basis (Narea) and chlorophyll on a mass basis (Chlmass) were measured in four co-dominant species (Acer rubrum, Fagus grandifolia, Pinus strobus and Quercus rubra) at different heights in plots with similar leaf area index (LAI) but contrasting canopy complexity (rugosity). We found that more complex canopies had greater porosity and reduced light variability in the midcanopy while total light interception was unchanged relative to less complex canopies. Leaves of F. grandifolia, Q. rubra, and P. strobus shifted towards sun-acclimation phenotypes with increasing canopy complexity while leaves of A. rubrum became more shade-acclimated (lower LMA) in the upper canopy of more complex stands, despite no differences in total light interception. Broadleaf species showed further acclimation by increasing Narea and reducing Chlmass as LMA increased, while P. strobus showed no change in Narea and Chlmass with increasing LMA. Our results provide new insight on how light distribution and leaf acclimation in mature trees might be altered when natural and anthropogenic disturbances cause structural changes in the canopy.

High-Resolution Seismic Velocity and Attenuation Models of the Caucasus-Caspian Region

DTIC Science & Technology

2009-09-30

region is part of the Alpine-Himalayan collision belt and is an area of complex structure accompanied by large variations in seismic wave velocities...velocity structure is developed using teleseismic receiver functions and surface waves. Joint inversion of surface wave group dispersion curves...Caucasus and the thinnest is in the Arabian Plate. Thin crust is also observed near the Caspian. The lithospheric mantle in the Greater Caucasus and the

Model structures amplify uncertainty in predicted soil carbon responses to climate change.

PubMed

Shi, Zheng; Crowell, Sean; Luo, Yiqi; Moore, Berrien

2018-06-04

Large model uncertainty in projected future soil carbon (C) dynamics has been well documented. However, our understanding of the sources of this uncertainty is limited. Here we quantify the uncertainties arising from model parameters, structures and their interactions, and how those uncertainties propagate through different models to projections of future soil carbon stocks. Both the vertically resolved model and the microbial explicit model project much greater uncertainties to climate change than the conventional soil C model, with both positive and negative C-climate feedbacks, whereas the conventional model consistently predicts positive soil C-climate feedback. Our findings suggest that diverse model structures are necessary to increase confidence in soil C projection. However, the larger uncertainty in the complex models also suggests that we need to strike a balance between model complexity and the need to include diverse model structures in order to forecast soil C dynamics with high confidence and low uncertainty.

Discrete structural features among interface residue-level classes.

PubMed

Sowmya, Gopichandran; Ranganathan, Shoba

2015-01-01

Protein-protein interaction (PPI) is essential for molecular functions in biological cells. Investigation on protein interfaces of known complexes is an important step towards deciphering the driving forces of PPIs. Each PPI complex is specific, sensitive and selective to binding. Therefore, we have estimated the relative difference in percentage of polar residues between surface and the interface for each complex in a non-redundant heterodimer dataset of 278 complexes to understand the predominant forces driving binding. Our analysis showed ~60% of protein complexes with surface polarity greater than interface polarity (designated as class A). However, a considerable number of complexes (~40%) have interface polarity greater than surface polarity, (designated as class B), with a significantly different p-value of 1.66E-45 from class A. Comprehensive analyses of protein complexes show that interface features such as interface area, interface polarity abundance, solvation free energy gain upon interface formation, binding energy and the percentage of interface charged residue abundance distinguish among class A and class B complexes, while electrostatic visualization maps also help differentiate interface classes among complexes. Class A complexes are classical with abundant non-polar interactions at the interface; however class B complexes have abundant polar interactions at the interface, similar to protein surface characteristics. Five physicochemical interface features analyzed from the protein heterodimer dataset are discriminatory among the interface residue-level classes. These novel observations find application in developing residue-level models for protein-protein binding prediction, protein-protein docking studies and interface inhibitor design as drugs.

Discrete structural features among interface residue-level classes

PubMed Central

2015-01-01

Background Protein-protein interaction (PPI) is essential for molecular functions in biological cells. Investigation on protein interfaces of known complexes is an important step towards deciphering the driving forces of PPIs. Each PPI complex is specific, sensitive and selective to binding. Therefore, we have estimated the relative difference in percentage of polar residues between surface and the interface for each complex in a non-redundant heterodimer dataset of 278 complexes to understand the predominant forces driving binding. Results Our analysis showed ~60% of protein complexes with surface polarity greater than interface polarity (designated as class A). However, a considerable number of complexes (~40%) have interface polarity greater than surface polarity, (designated as class B), with a significantly different p-value of 1.66E-45 from class A. Comprehensive analyses of protein complexes show that interface features such as interface area, interface polarity abundance, solvation free energy gain upon interface formation, binding energy and the percentage of interface charged residue abundance distinguish among class A and class B complexes, while electrostatic visualization maps also help differentiate interface classes among complexes. Conclusions Class A complexes are classical with abundant non-polar interactions at the interface; however class B complexes have abundant polar interactions at the interface, similar to protein surface characteristics. Five physicochemical interface features analyzed from the protein heterodimer dataset are discriminatory among the interface residue-level classes. These novel observations find application in developing residue-level models for protein-protein binding prediction, protein-protein docking studies and interface inhibitor design as drugs. PMID:26679043

The complex and specific pMHC interactions with diverse HIV-1 TCR clonotypes reveal a structural basis for alterations in CTL function

NASA Astrophysics Data System (ADS)

Xia, Zhen; Chen, Huabiao; Kang, Seung-Gu; Huynh, Tien; Fang, Justin W.; Lamothe, Pedro A.; Walker, Bruce D.; Zhou, Ruhong

2014-02-01

Immune control of viral infections is modulated by diverse T cell receptor (TCR) clonotypes engaging peptide-MHC class I complexes on infected cells, but the relationship between TCR structure and antiviral function is unclear. Here we apply in silico molecular modeling with in vivo mutagenesis studies to investigate TCR-pMHC interactions from multiple CTL clonotypes specific for a well-defined HIV-1 epitope. Our molecular dynamics simulations of viral peptide-HLA-TCR complexes, based on two independent co-crystal structure templates, reveal that effective and ineffective clonotypes bind to the terminal portions of the peptide-MHC through similar salt bridges, but their hydrophobic side-chain packings can be very different, which accounts for the major part of the differences among these clonotypes. Non-specific hydrogen bonding to viral peptide also accommodates greater epitope variants. Furthermore, free energy perturbation calculations for point mutations on the viral peptide KK10 show excellent agreement with in vivo mutagenesis assays, with new predictions confirmed by additional experiments. These findings indicate a direct structural basis for heterogeneous CTL antiviral function.

Blue light emission from cyclometallated iridium (III) cyano complexes: Syntheses, crystal structures, and photophysical properties

DOE PAGES

Sanner, Robert D.; Cherepy, Nerine J.; Young, Jr., Victor G.

2015-11-02

In this study, we describe the synthesis and crystal structures of four iridium compounds containing the 2-(4,6-difluorophenyl)pyridyl ligand. Cleavage of dichloro-bridged iridium(III) dimers with phosphorus ligands leads to (46dfppy)2Ir(L)(Cl) where L = PPh 3 or P(OPh) 3. Treatment of the chloro compounds with cyanide forms the cyano complexes (46dfppy) 2Ir(L)(CN). All complexes exhibit a trans effect in their molecular structures due to the phosphorus ligands, with the phosphite having a greater effect than the phosphine. With L = PPh 3, blue photoluminescence with CIE coordinates (x = 0.16, y = 0.24), quantum yield of 0.66 ± 0.15 and 4.5 ±more » 0.5 μs decay time is measured. For L = P(OPh) 3, blue photoluminescence with CIE coordinates (x = 0.16, y = 0.21), quantum yield of 0.65 ± 0.15 and 2.9 ± 0.3 μs decay time is measured.« less

Technetium-99m and rhenium-188 complexes with one and two pendant bisphosphonate groups for imaging arterial calcification.

PubMed

Bordoloi, Jayanta Kumar; Berry, David; Khan, Irfan Ullah; Sunassee, Kavitha; de Rosales, Rafael Torres Martin; Shanahan, Catherine; Blower, Philip J

2015-03-21

The first (99m)Tc and (188)Re complexes containing two pendant bisphosphonate groups have been synthesised, based on the mononuclear M(v) nitride core with two dithiocarbamate ligands each with a pendant bisphosphonate. The structural identity of the (99)Tc and stable rhenium analogues as uncharged, mononuclear nitridobis(dithiocarbamate) complexes was determined by electrospray mass spectrometry. The (99m)Tc complex showed greater affinity for synthetic and biological hydroxyapatite, and greater stability in biological media, than the well-known but poorly-characterised and inhomogeneous bone imaging agent (99m)Tc-MDP. It gave excellent SPECT images of both bone calcification (mice and rats) and vascular calcification (rat model), but the improved stability and the availability of two pendant bisphosphonate groups conferred no dramatic advantage in imaging over the conventional (99m)Tc-MDP agent in which the bisphosphonate group is bound directly to Tc. The (188)Re complex also showed preferential uptake in bone. These tracers and the biological model of vascular calcification offer the opportunity to study the biological interpretation and clinical potential of radionuclide imaging of vascular calcification and to deliver radionuclide therapy to bone metastases.

Broca's Area Plays a Causal Role in Morphosyntactic Processing

ERIC Educational Resources Information Center

Carreiras, Manuel; Pattamadilok, Chotiga; Meseguer, Enrique; Barber, Horacio; Devlin, Joseph T.

2012-01-01

Although there is strong evidence that Broca's area is important for syntax, this may simply be a by-product of greater working memory and/or cognitive control demands for more complex syntactic structures. Here we report an experiment with event-related transcranial magnetic stimulation (TMS) to investigate whether Broca's area plays a causal…

New Realities in the Management of Student Affairs: Emerging Specialist Roles and Structures for Changing Times

ERIC Educational Resources Information Center

Tull, Ashley, Ed.; Kuk, Linda, Ed.

2012-01-01

Student affairs organizations are at a crossroads. They face expanding enrollments; a concomitant increase need for often more complex services; changing demographics; a growing cohort of non-traditional and first-generation students; shifting and more demanding responsibilities; and increased expectations from the greater campus community,…

Study of base pair mutations in proline-rich homeodomain (PRH)-DNA complexes using molecular dynamics.

PubMed

Jalili, Seifollah; Karami, Leila; Schofield, Jeremy

2013-06-01

Proline-rich homeodomain (PRH) is a regulatory protein controlling transcription and gene expression processes by binding to the specific sequence of DNA, especially to the sequence 5'-TAATNN-3'. The impact of base pair mutations on the binding between the PRH protein and DNA is investigated using molecular dynamics and free energy simulations to identify DNA sequences that form stable complexes with PRH. Three 20-ns molecular dynamics simulations (PRH-TAATTG, PRH-TAATTA and PRH-TAATGG complexes) in explicit solvent water were performed to investigate three complexes structurally. Structural analysis shows that the native TAATTG sequence forms a complex that is more stable than complexes with base pair mutations. It is also observed that upon mutation, the number and occupancy of the direct and water-mediated hydrogen bonds decrease. Free energy calculations performed with the thermodynamic integration method predict relative binding free energies of 0.64 and 2 kcal/mol for GC to AT and TA to GC mutations, respectively, suggesting that among the three DNA sequences, the PRH-TAATTG complex is more stable than the two mutated complexes. In addition, it is demonstrated that the stability of the PRH-TAATTA complex is greater than that of the PRH-TAATGG complex.

Reversibility in Quantum Models of Stochastic Processes

NASA Astrophysics Data System (ADS)

Gier, David; Crutchfield, James; Mahoney, John; James, Ryan

Natural phenomena such as time series of neural firing, orientation of layers in crystal stacking and successive measurements in spin-systems are inherently probabilistic. The provably minimal classical models of such stochastic processes are ɛ-machines, which consist of internal states, transition probabilities between states and output values. The topological properties of the ɛ-machine for a given process characterize the structure, memory and patterns of that process. However ɛ-machines are often not ideal because their statistical complexity (Cμ) is demonstrably greater than the excess entropy (E) of the processes they represent. Quantum models (q-machines) of the same processes can do better in that their statistical complexity (Cq) obeys the relation Cμ >= Cq >= E. q-machines can be constructed to consider longer lengths of strings, resulting in greater compression. With code-words of sufficiently long length, the statistical complexity becomes time-symmetric - a feature apparently novel to this quantum representation. This result has ramifications for compression of classical information in quantum computing and quantum communication technology.

Formation mechanism and biological activity of novel thiolated human-like collagen iron complex.

PubMed

Zhu, Chenhui; Liu, Lingyun; Deng, Jianjun; Ma, Xiaoxuan; Hui, Junfeng; Fan, Daidi

2016-03-01

To develop an iron supplement that is effectively absorbed and utilized, thiolated human-like collagen was created to improve the iron binding capacity of human-like collagen. A thiolated human-like collagen-iron complex was prepared in a phosphate buffer, and one mole of thiolated human-like collagen-iron possessed approximately 28.83 moles of iron. The characteristics of thiolated human-like collagen-iron were investigated by ultraviolet-visible absorption spectroscopy, Fourier transform infrared spectroscopy, circular dichroism, and differential scanning calorimetry. The results showed that the thiolated human-like collagen-iron complex retained the secondary structure of human-like collagen and had greater thermodynamic stability than human-like collagen, although interactions between iron ions and human-like collagen occurred during the formation of the complex. In addition, to evaluate the bioavailability of thiolated human-like collagen-iron, an in vitro Caco-2 cell model and an in vivo iron deficiency anemia mouse model were employed. The data demonstrated that the thiolated human-like collagen-iron complex exhibited greater bioavailability and was more easily utilized than FeSO4, ferric ammonium citrate, or ferrous glycinate. These results indicated that the thiolated human-like collagen-iron complex is a potential iron supplement in the biomedical field. © The Author(s) 2016.

Hemifacial Pain and Hemisensory Disturbance Referred from Occipital Neuralgia Caused by Pathological Vascular Contact of the Greater Occipital Nerve

PubMed Central

Choi, Jin-gyu

2017-01-01

Here we report a unique case of chronic occipital neuralgia caused by pathological vascular contact of the left greater occipital nerve. After 12 months of left-sided, unremitting occipital neuralgia, a hypesthesia and facial pain developed in the left hemiface. The decompression of the left greater occipital nerve from pathological contacts with the occipital artery resulted in immediate relief for hemifacial sensory change and facial pain, as well as chronic occipital neuralgia. Although referral of pain from the stimulation of occipital and cervical structures innervated by upper cervical nerves to the frontal head of V1 trigeminal distribution has been reported, the development of hemifacial sensory change associated with referred trigeminal pain from chronic occipital neuralgia is extremely rare. Chronic continuous and strong afferent input of occipital neuralgia caused by pathological vascular contact with the greater occipital nerve seemed to be associated with sensitization and hypersensitivity of the second-order neurons in the trigeminocervical complex, a population of neurons in the C2 dorsal horn characterized by receiving convergent input from dural and cervical structures. PMID:28331643

Hemifacial Pain and Hemisensory Disturbance Referred from Occipital Neuralgia Caused by Pathological Vascular Contact of the Greater Occipital Nerve.

PubMed

Son, Byung-Chul; Choi, Jin-Gyu

2017-01-01

Here we report a unique case of chronic occipital neuralgia caused by pathological vascular contact of the left greater occipital nerve. After 12 months of left-sided, unremitting occipital neuralgia, a hypesthesia and facial pain developed in the left hemiface. The decompression of the left greater occipital nerve from pathological contacts with the occipital artery resulted in immediate relief for hemifacial sensory change and facial pain, as well as chronic occipital neuralgia. Although referral of pain from the stimulation of occipital and cervical structures innervated by upper cervical nerves to the frontal head of V1 trigeminal distribution has been reported, the development of hemifacial sensory change associated with referred trigeminal pain from chronic occipital neuralgia is extremely rare. Chronic continuous and strong afferent input of occipital neuralgia caused by pathological vascular contact with the greater occipital nerve seemed to be associated with sensitization and hypersensitivity of the second-order neurons in the trigeminocervical complex, a population of neurons in the C2 dorsal horn characterized by receiving convergent input from dural and cervical structures.

Site-Selective Benzannulation of N-Heterocycles in Bidentate Ligands Leads to Blue-Shifted Emission from [( P^N)Cu]2(μ-X)2 Dimers.

PubMed

Mondal, Rajarshi; Lozada, Issiah B; Davis, Rebecca L; Williams, J A Gareth; Herbert, David E

2018-05-07

Benzannulated bidentate pyridine/phosphine ( P^N) ligands bearing quinoline or phenanthridine (3,4-benzoquinoline) units have been prepared, along with their halide-bridged, dimeric Cu(I) complexes of the form [( P^N)Cu] 2 (μ-X) 2 . The copper complexes are phosphorescent in the orange-red region of the spectrum in the solid-state under ambient conditions. Structural characterization in solution and the solid-state reveals a flexible conformational landscape, with both diamond-like and butterfly motifs available to the Cu 2 X 2 cores. Comparing the photophysical properties of complexes of (quinolinyl)phosphine ligands with those of π-extended (phenanthridinyl)phosphines has revealed a counterintuitive impact of site-selective benzannulation. Contrary to conventional assumptions regarding π-extension and a bathochromic shift in the lowest energy absorption maxima, a blue shift of nearly 40 nm in the emission wavelength is observed for the complexes with larger ligand π-systems, which is assigned as phosphorescence on the basis of emission energies and lifetimes. Comparison of the ground-state and triplet excited state structures optimized from DFT and TD-DFT calculations allows attribution of this effect to a greater rigidity for the benzannulated complexes resulting in a higher energy emissive triplet state, rather than significant perturbation of orbital energies. This study reveals that ligand structure can impact photophysical properties for emissive molecules by influencing their structural rigidity, in addition to their electronic structure.

Analysis of interstellar fragmentation structure based on IRAS images

NASA Technical Reports Server (NTRS)

Scalo, John M.

1989-01-01

The goal of this project was to develop new tools for the analysis of the structure of densely sampled maps of interstellar star-forming regions. A particular emphasis was on the recognition and characterization of nested hierarchical structure and fractal irregularity, and their relation to the level of star formation activity. The panoramic IRAS images provided data with the required range in spatial scale, greater than a factor of 100, and in column density, greater than a factor of 50. In order to construct a densely sampled column density map of a cloud complex which is both self-gravitating and not (yet?) stirred up much by star formation, a column density image of the Taurus region has been constructed from IRAS data. The primary drawback to using the IRAS data for this purpose is that it contains no velocity information, and the possible importance of projection effects must be kept in mind.

Complexity in the new NHS: longitudinal case studies of CCGs in England

PubMed Central

Checkland, Katherine; Coleman, Anna; Perkins, Neil

2016-01-01

Objective The reform in the English National Health Services (NHS) under the Health and Social Care Act 2012 is unlike previous NHS reorganisations. The establishment of clinical commissioning groups (CCGs) was intended to be ‘bottom up’ with no central blueprint. This paper sets out to offer evidence about how this process has played out in practice and examines the implications of the complexity and variation which emerged. Design Detailed case studies in CCGs across England, using interviews, observation and documentary analysis. Using realist framework, we unpacked the complexity of CCG structures. Setting/participants In phase 1 of the study (January 2011 to September 2012), we conducted 96 interviews, 439 h of observation in a wide variety of meetings, 2 online surveys and 38 follow-up telephone interviews. In phase 2 (April 2013 to March 2015), we conducted 42 interviews with general practitioners (GPs) and managers and observation of 48 different types of meetings. Results Our study has highlighted the complexity inherent in CCGs, arising out of the relatively permissive environment in which they developed. Not only are they very different from one another in size, but also in structure, functions between different bodies and the roles played by GPs. Conclusions The complexity and lack of uniformity of CCGs is important as it makes it difficult for those who must engage with CCGs to know who to approach at what level. This is of increasing importance as CCGs are moving towards greater integration across health and social care. Our study also suggests that there is little consensus as to what being a ‘membership’ organisation means and how it should operate. The lack of uniformity in CCG structure and lack of clarity over the meaning of ‘membership’ raises questions over accountability, which becomes of greater importance as CCG is taking over responsibility for primary care co-commissioning. PMID:26743708

Complexity in the new NHS: longitudinal case studies of CCGs in England.

PubMed

Checkland, Katherine; McDermott, Imelda; Coleman, Anna; Perkins, Neil

2016-01-07

The reform in the English National Health Services (NHS) under the Health and Social Care Act 2012 is unlike previous NHS reorganisations. The establishment of clinical commissioning groups (CCGs) was intended to be 'bottom up' with no central blueprint. This paper sets out to offer evidence about how this process has played out in practice and examines the implications of the complexity and variation which emerged. Detailed case studies in CCGs across England, using interviews, observation and documentary analysis. Using realist framework, we unpacked the complexity of CCG structures. In phase 1 of the study (January 2011 to September 2012), we conducted 96 interviews, 439 h of observation in a wide variety of meetings, 2 online surveys and 38 follow-up telephone interviews. In phase 2 (April 2013 to March 2015), we conducted 42 interviews with general practitioners (GPs) and managers and observation of 48 different types of meetings. Our study has highlighted the complexity inherent in CCGs, arising out of the relatively permissive environment in which they developed. Not only are they very different from one another in size, but also in structure, functions between different bodies and the roles played by GPs. The complexity and lack of uniformity of CCGs is important as it makes it difficult for those who must engage with CCGs to know who to approach at what level. This is of increasing importance as CCGs are moving towards greater integration across health and social care. Our study also suggests that there is little consensus as to what being a 'membership' organisation means and how it should operate. The lack of uniformity in CCG structure and lack of clarity over the meaning of 'membership' raises questions over accountability, which becomes of greater importance as CCG is taking over responsibility for primary care co-commissioning. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Habitat structure mediates predation risk for sedentary prey: Experimental tests of alternative hypotheses

USGS Publications Warehouse

Chalfoun, A.D.; Martin, T.E.

2009-01-01

Predation is an important and ubiquitous selective force that can shape habitat preferences of prey species, but tests of alternative mechanistic hypotheses of habitat influences on predation risk are lacking. 2. We studied predation risk at nest sites of a passerine bird and tested two hypotheses based on theories of predator foraging behaviour. The total-foliage hypothesis predicts that predation will decline in areas of greater overall vegetation density by impeding cues for detection by predators. The potential-prey-site hypothesis predicts that predation decreases where predators must search more unoccupied potential nest sites. 3. Both observational data and results from a habitat manipulation provided clear support for the potential-prey-site hypothesis and rejection of the total-foliage hypothesis. Birds chose nest patches containing both greater total foliage and potential nest site density (which were correlated in their abundance) than at random sites, yet only potential nest site density significantly influenced nest predation risk. 4. Our results therefore provided a clear and rare example of adaptive nest site selection that would have been missed had structural complexity or total vegetation density been considered alone. 5. Our results also demonstrated that interactions between predator foraging success and habitat structure can be more complex than simple impedance or occlusion by vegetation. ?? 2008 British Ecological Society.

Effects of structural complexity on within-canopy light environments and leaf traits in a northern mixed deciduous forest.

PubMed

Fotis, Alexander T; Curtis, Peter S

2017-10-01

Canopy structure influences forest productivity through its effects on the distribution of radiation and the light-induced changes in leaf physiological traits. Due to the difficulty of accessing and measuring forest canopies, few field-based studies have quantitatively linked these divergent scales of canopy functioning. The objective of our study was to investigate how canopy structure affects light profiles within a forest canopy and whether leaves of mature trees adjust morphologically and biochemically to the light environments characteristic of canopies with different structural complexity. We used a combination of light detection and ranging (LiDAR) data and hemispherical photographs to quantify canopy structure and light environments, respectively, and a telescoping pole to sample leaves. Leaf mass per area (LMA), nitrogen on an area basis (Narea) and chlorophyll on a mass basis (Chlmass) were measured in red maple (Acer rubrum), american beech (Fagus grandifolia), white pine (Pinus strobus), and northern red oak (Quercus rubra) at different heights in plots with similar leaf area index but contrasting canopy complexity (rugosity). We found that more complex canopies had greater porosity and reduced light variability in the midcanopy while total light interception was unchanged relative to less complex canopies. Leaf phenotypes of F. grandifolia, Q. rubra and P. strobus were more sun-acclimated in the midstory of structurally complex canopies while leaf phenotypes of A. rubrum were more shade-acclimated (lower LMA) in the upper canopy of more complex stands, despite no differences in total light interception. Broadleaf species showed further differences in acclimation with increased Narea and reduced Chlmass in leaves with higher LMA, while P. strobus showed no change in Narea and Chlmass with higher LMA. Our results provide new insight on how light distribution and leaf acclimation in mature trees might be altered when natural and anthropogenic disturbances cause structural changes in the canopy. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Structural analysis of muscles elevating the hyolaryngeal complex.

PubMed

Pearson, William G; Langmore, Susan E; Yu, Louis B; Zumwalt, Ann C

2012-12-01

A critical event of pharyngeal swallowing is the elevation of the hyolaryngeal complex to open the upper esophageal sphincter. Current swallowing theory assigns this function to the submental and thyrohyoid muscles. However, the attachments of the long pharyngeal muscles indicate that they could contribute to this function, yet their role is uninvestigated in humans. In addition, there is evidence the posterior digastric and stylohyoid contribute to hyoid elevation. A cadaver model was used to document the structural properties of muscles. These properties were used to model muscle groups as force vectors and analyze their potential for hyolaryngeal elevation. Vector magnitude was determined using physiological cross-sectional areas (PCSAs) of muscles calculated from structural properties of muscle taken from 12 hemisected cadaver specimens. Vector direction (lines of action) was calculated from the three-dimensional coordinates of muscle attachment sites. Unit force vectors in the superior direction of submental, suprahyoid (which includes the submental muscles), long pharyngeal, and thyrohyoid muscles were derived and compared by an analysis of variance (ANOVA) to document each muscle's potential contribution to hyolaryngeal elevation. An ANOVA with Tukey HSD post hoc analysis of unit force vectors showed no statistically significant difference between the submental (0.92 ± 0.24 cm(2)) and long pharyngeal (0.73 ± 0.20 cm(2)) muscles. Both demonstrated greater potential to elevate the hyolaryngeal complex than the thyrohyoid (0.49 ± 0.18 cm(2)), with P < 0.01 and P < 0.05, respectively. The suprahyoid muscles (1.52 ± 0.35 cm(2)) demonstrated the greatest potential to elevate the hyolaryngeal complex: greater than both the long pharyngeal muscles (P < 0.01) and the thyrohyoid (P < 0.01). The submental and thyrohyoid muscles by convention are thought to elevate the hyolaryngeal complex. This study demonstrates that structurally the long pharyngeal muscles have similar potential to contribute to this critical function, with the suprahyoid muscles having the greatest potential. If verified by functional data, these findings would amend current swallowing theory.

Proportional plus integral MIMO controller for regulation and tracking with anti-wind-up features

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puleston, P.F.; Mantz, R.J.

1993-11-01

A proportional plus integral matrix control structure for MIMO systems is proposed. Based on a standard optimal control structure with integral action, it permits a greater degree of independence of the design and tuning of the regulating and tracking features, without considerably increasing the controller complexity. Fast recovery from load disturbances is achieved, while large overshoots associated with set-point changes and reset wind-up problems can be reduced. A simple effective procedure for practical tuning is introduced.

Global Report on Adult Learning and Education

ERIC Educational Resources Information Center

Chisholm, Lynne, Ed.; Hasan, Abrar, Ed.

2010-01-01

In the 21st century, the rapid pace and complexity of economic, technological and cultural changes require women and men to adapt and re-adapt throughout their lives--all the more so in the context of globalisation. In this era of the knowledge society--where production structure is shifting towards greater knowledge use and away from reliance on…

Thermospheric O/N2 in the Sunlit Disk From More Than Five Years of GUVI/TIMED Observations

NASA Astrophysics Data System (ADS)

Craven, J. D.; Christensen, A. B.; Paxton, L. J.

2007-12-01

GUVI indirect observations of the thermospheric column density ratio, O/N2, in the sunlit hemisphere have been made on a nearly continuous basis from day 50 of 2002 to the present as part of the TIMED spacecraft mission. The basic large-scale spatial structure includes variations with local time (greater values in the morning), Universal Time (modulation at high latitudes due to the offset magnetic dipole), and season (greater values in the local winter hemisphere). These differences are seen to fade in the approach to solar minimum. Superposed on this reasonably well-behaved background structure are the complex, transient perturbations driven by auroral substorms and geomagnetic storms. The spatial and temporal variations are summarized in part by time-lapse movies

Edible carbohydrates from formaldehyde in a spacecraft

NASA Technical Reports Server (NTRS)

Weiss, A. H.

1975-01-01

The autocatalytic nature of the base catalyzed condensation of formaldehyde to formose sugars is eliminated by using as a cocatalyst, an aldose, or ketose having an alpha-hydrogen. This is more strongly complexed by base than is formaldehyde and the cocatalyst and sugar products accumulate as catalyst complexes instead of formaldehyde. Because of the presence of alpha-hydrogen atoms in cocatalysts and formose sugars, their removal by cross Cannizzaro reaction of complexed sugars does not occur, so the formose reaction behaves autocatalytically due to this accumulation. It is believed that a given catalytic formose complex is not a discrete complexed sugar, but rather, a scrambled dynamic mixture of sugars having weakened structures. The sugar complexes derive from a common salt-like formaldehyde complex, which, because of the absence of alpha-hydrogen, has a greater tendency to undergo Cannizzaro reaction, rather than formose condensation. Because of this, the Cannizzaro reaction can proceed without measurable formose condensation. The reverse is not possible.

A new quadruple hydrogen-bonding module based on five-membered heterocyclic urea structure.

PubMed

Hisamatsu, Yosuke; Shirai, Naohiro; Ikeda, Shin-Ichi; Odashima, Kazunori

2010-04-16

N,N'-Di-4-triazolylurea (DTU) has developed as a new ADDA module and DTU forms a stable ADDA*DAAD heterocomplex with 2,7-diamido-1,8-naphthyridine (DAN) (K(s) = 2.6 x 10(5) M(-1) in CHCl(3)). The K(s) value of the complex between DTU and DAN is 100-fold greater than that of the complex between N,N'-di-2-pyridylurea and DAN due to replacement of a pyridine ring with a 1,2,3-triazole ring.

Stereo Science Results at Solar Minimum

NASA Technical Reports Server (NTRS)

Christian, Eric R.; Kaiser, Michael L.; Kucera Therese A.; St. Cyr, O. C.; van Driel-Gesztelyi, Lidia; Mandrini, Cristina H.

2009-01-01

The magnetic fields that drive solar activity are complex and inherently three-dimensional structures. Twisted flux ropes, magnetic reconnection and the initiation of solar storms, as well as space weather propagation through the heliosphere, are just a few of the topics that cannot properly be observed or modeled in only two dimensions. Examination of this three-dimensional complex has been hampered by the fact that solar remote sensing observations have occurred only from the Earth-Sun line, and in situ observations, while available from a greater variety of locations, have been sparse throughout the heliosphere.

Nonlinear complex dynamics and Keynesian rigidity: A short introduction

NASA Astrophysics Data System (ADS)

Jovero, Edgardo

2005-09-01

The topic of this paper is to show that the greater acceptance and intense use of complex nonlinear dynamics in macroeconomics makes sense only within the neoKeynesian tradition. An example is presented regarding the behavior of an open-economy two-sector growth model endowed with Keynesian rigidity. The Keynesian view that structural instability globally exists in the aggregate economy is put forward, and therefore the need arises for policy to alleviate this instability in the form of dampened fluctuations is presented as an alternative view for macroeconomic theorizing.

Virtual interface substructure synthesis method for normal mode analysis of super-large molecular complexes at atomic resolution.

PubMed

Chen, Xuehui; Sun, Yunxiang; An, Xiongbo; Ming, Dengming

2011-10-14

Normal mode analysis of large biomolecular complexes at atomic resolution remains challenging in computational structure biology due to the requirement of large amount of memory space and central processing unit time. In this paper, we present a method called virtual interface substructure synthesis method or VISSM to calculate approximate normal modes of large biomolecular complexes at atomic resolution. VISSM introduces the subunit interfaces as independent substructures that join contacting molecules so as to keep the integrity of the system. Compared with other approximate methods, VISSM delivers atomic modes with no need of a coarse-graining-then-projection procedure. The method was examined for 54 protein-complexes with the conventional all-atom normal mode analysis using CHARMM simulation program and the overlap of the first 100 low-frequency modes is greater than 0.7 for 49 complexes, indicating its accuracy and reliability. We then applied VISSM to the satellite panicum mosaic virus (SPMV, 78,300 atoms) and to F-actin filament structures of up to 39-mer, 228,813 atoms and found that VISSM calculations capture functionally important conformational changes accessible to these structures at atomic resolution. Our results support the idea that the dynamics of a large biomolecular complex might be understood based on the motions of its component subunits and the way in which subunits bind one another. © 2011 American Institute of Physics

Structural and spectroscopic study of Al(III)-3-hydroxyflavone complex: determination of the stability constants in water-methanol mixtures.

PubMed

Davila, Y A; Sancho, M I; Almandoz, M C; Blanco, S E

2012-09-01

Stoichiometry and apparent stability constant (K(C)) of the complex formed between Al(III) and 3-hydroxyflavone were determined in methanol and water-methanol mixtures (% water w/w: 3.11; 6.15; 10.4; 15.2; 19.9 and 25.3) by UV-vis spectroscopy at 25.0°C and constant ionic strength (0.05 M, sodium chloride). Stoichiometry of the complex (1:2, metal:ligand) is not modified with an increase in water percentage in the analyzed interval. The value of K(C) in methanol is greater than in the binary solutions. The effects of changing solvent composition on K(C) data were explained by linear solvation free energy relationships using the solvatochromic parameter of Kamlet and Taft (α, β and π(*)). Multiple linear regression analysis indicates that the hydrogen bond donating ability (α) of the solvent and non-specific interactions (π(*)) play an important role in the degree of occurrence of the reaction. The effect of temperature on K(C) was also analyzed by assessing standard entropy and enthalpy variations of the reaction in methanol. Finally, the structure of the complex was investigated using FTIR spectroscopy and DFT calculations. The ligand exhibits small structural changes upon complexation, localized on the chelating site. The calculated vibrational frequencies of the complex were successfully compared against the experimental values. Copyright © 2012 Elsevier B.V. All rights reserved.

Complexation of rice starch/flour and maize oil through heat moisture treatment: Structural, in vitro digestion and physicochemical properties.

PubMed

Chen, Xu; He, Xiaowei; Fu, Xiong; Zhang, Bin; Huang, Qiang

2017-05-01

This study investigated structural, in vitro digestion and physicochemical properties of normal rice starch (NRS)/flour (NRF) complexed with maize oil (MO) through heat-moisture treatment (HMT). The NRS-/NRF-MO complex displayed an increased pasting temperature and a decreased peak viscosity. After HMT, less ordered Maltese and more granule fragments were observed for NRS-/NRF-MO complex. Meanwhile, more aggregation was observed in the HMT samples with higher moisture contents. We found that higher onset temperature, lower enthalpy change and relative crystallinity of the NRS-/NRF-MO complex were associated with a higher moisture content of HMT samples. The higher moisture content of HMT was also favorable for the amylose-lipid complex formation. Differences in starch digestion properties were found for NRS-MO and NRF-MO complex. All of the NRS/NRF complexed MO after cooking showed lower rapidly digestible starch (RDS) contents compared with the control sample, therein NRS-/NRF- MO 20% exhibited the highest sum of the slowly digestible starch and resistant starch contents. In general, HMT had a greater impact on the in vitro digestion and physicochemical properties of flour samples compared with starch counterparts. Copyright © 2017 Elsevier B.V. All rights reserved.

Dorso-medial and ventro-lateral functional specialization of the human retrosplenial complex in spatial updating and orienting.

PubMed

Burles, Ford; Slone, Edward; Iaria, Giuseppe

2017-04-01

The retrosplenial complex is a region within the posterior cingulate cortex implicated in spatial navigation. Here, we investigated the functional specialization of this large and anatomically heterogeneous region using fMRI and resting-state functional connectivity combined with a spatial task with distinct phases of spatial 'updating' (i.e., integrating and maintaining object locations in memory during spatial displacement) and 'orienting' (i.e., recalling unseen locations from current position in space). Both spatial 'updating' and 'orienting' produced bilateral activity in the retrosplenial complex, among other areas. However, spatial 'updating' produced slightly greater activity in ventro-lateral portions, of the retrosplenial complex, whereas spatial 'orienting' produced greater activity in a more dorsal and medial portion of it (both regions localized along the parieto-occipital fissure). At rest, both ventro-lateral and dorso-medial subregions of the retrosplenial complex were functionally connected to the hippocampus and parahippocampus, regions both involved in spatial orientation and navigation. However, the ventro-lateral subregion of the retrosplenial complex displayed more positive functional connectivity with ventral occipital and temporal object recognition regions, whereas the dorso-medial subregion activity was more correlated to dorsal activity and frontal activity, as well as negatively correlated with more ventral parietal structures. These findings provide evidence for a dorso-medial to ventro-lateral functional specialization within the human retrosplenial complex that may shed more light on the complex neural mechanisms underlying spatial orientation and navigation in humans.

The role of complex emotions in inconsistent diagnoses of schizophrenia.

PubMed

Gara, Michael A; Vega, William A; Lesser, Ira; Escamilla, Michael; Lawson, William B; Wilson, Daniel R; Fleck, David E; Strakowski, Stephen M

2010-09-01

In the case of large-scale epidemiological studies, there is evidence of substantial disagreement when lay diagnoses of schizophrenia based on structured interviews are compared with expert diagnoses of the same patients. Reasons for this level of disagreement are investigated in the current study, which made use of advances in text-mining techniques and associated structural representations of language expressions. Specifically, the current study examined whether content analyses of transcribed diagnostic interviews obtained from 150 persons with serious psychiatric disorders yielded any discernable patterns that correlated with diagnostic inconsistencies of schizophrenia. In summary, it was found that the patterning or structure of spontaneous self-reports of emotion states in the diagnostic interview was associated with diagnostic inconsistencies of schizophrenia, irrespective of confounders; i.e., age of patient, gender, or ethnicity. In particular, complex emotion patterns were associated with greater disagreement between experts and trained lay interviewers than were simpler patterns.

Digital Reef Rugosity Estimates Coral Reef Habitat Complexity

PubMed Central

Dustan, Phillip; Doherty, Orla; Pardede, Shinta

2013-01-01

Ecological habitats with greater structural complexity contain more species due to increased niche diversity. This is especially apparent on coral reefs where individual coral colonies aggregate to give a reef its morphology, species zonation, and three dimensionality. Structural complexity is classically measured with a reef rugosity index, which is the ratio of a straight line transect to the distance a flexible chain of equal length travels when draped over the reef substrate; yet, other techniques from visual categories to remote sensing have been used to characterize structural complexity at scales from microhabitats to reefscapes. Reef-scale methods either lack quantitative precision or are too time consuming to be routinely practical, while remotely sensed indices are mismatched to the finer scale morphology of coral colonies and reef habitats. In this communication a new digital technique, Digital Reef Rugosity (DRR) is described which utilizes a self-contained water level gauge enabling a diver to quickly and accurately characterize rugosity with non-invasive millimeter scale measurements of coral reef surface height at decimeter intervals along meter scale transects. The precise measurements require very little post-processing and are easily imported into a spreadsheet for statistical analyses and modeling. To assess its applicability we investigated the relationship between DRR and fish community structure at four coral reef sites on Menjangan Island off the northwest corner of Bali, Indonesia and one on mainland Bali to the west of Menjangan Island; our findings show a positive relationship between DRR and fish diversity. Since structural complexity drives key ecological processes on coral reefs, we consider that DRR may become a useful quantitative community-level descriptor to characterize reef complexity. PMID:23437380

Digital reef rugosity estimates coral reef habitat complexity.

PubMed

Dustan, Phillip; Doherty, Orla; Pardede, Shinta

2013-01-01

Ecological habitats with greater structural complexity contain more species due to increased niche diversity. This is especially apparent on coral reefs where individual coral colonies aggregate to give a reef its morphology, species zonation, and three dimensionality. Structural complexity is classically measured with a reef rugosity index, which is the ratio of a straight line transect to the distance a flexible chain of equal length travels when draped over the reef substrate; yet, other techniques from visual categories to remote sensing have been used to characterize structural complexity at scales from microhabitats to reefscapes. Reef-scale methods either lack quantitative precision or are too time consuming to be routinely practical, while remotely sensed indices are mismatched to the finer scale morphology of coral colonies and reef habitats. In this communication a new digital technique, Digital Reef Rugosity (DRR) is described which utilizes a self-contained water level gauge enabling a diver to quickly and accurately characterize rugosity with non-invasive millimeter scale measurements of coral reef surface height at decimeter intervals along meter scale transects. The precise measurements require very little post-processing and are easily imported into a spreadsheet for statistical analyses and modeling. To assess its applicability we investigated the relationship between DRR and fish community structure at four coral reef sites on Menjangan Island off the northwest corner of Bali, Indonesia and one on mainland Bali to the west of Menjangan Island; our findings show a positive relationship between DRR and fish diversity. Since structural complexity drives key ecological processes on coral reefs, we consider that DRR may become a useful quantitative community-level descriptor to characterize reef complexity.

The complex and specific pMHC interactions with diverse HIV-1 TCR clonotypes reveal a structural basis for alterations in CTL function

PubMed Central

Xia, Zhen; Chen, Huabiao; Kang, Seung-gu; Huynh, Tien; Fang, Justin W.; Lamothe, Pedro A.; Walker, Bruce D.; Zhou, Ruhong

2014-01-01

Immune control of viral infections is modulated by diverse T cell receptor (TCR) clonotypes engaging peptide-MHC class I complexes on infected cells, but the relationship between TCR structure and antiviral function is unclear. Here we apply in silico molecular modeling with in vivo mutagenesis studies to investigate TCR-pMHC interactions from multiple CTL clonotypes specific for a well-defined HIV-1 epitope. Our molecular dynamics simulations of viral peptide-HLA-TCR complexes, based on two independent co-crystal structure templates, reveal that effective and ineffective clonotypes bind to the terminal portions of the peptide-MHC through similar salt bridges, but their hydrophobic side-chain packings can be very different, which accounts for the major part of the differences among these clonotypes. Non-specific hydrogen bonding to viral peptide also accommodates greater epitope variants. Furthermore, free energy perturbation calculations for point mutations on the viral peptide KK10 show excellent agreement with in vivo mutagenesis assays, with new predictions confirmed by additional experiments. These findings indicate a direct structural basis for heterogeneous CTL antiviral function. PMID:24522437

Microwave structure for the propiolic acid-formic acid complex.

PubMed

Kukolich, Stephen G; Mitchell, Erik G; Carey, Spencer J; Sun, Ming; Sargus, Bryan A

2013-10-03

New microwave spectra were measured to obtain rotational constants and centrifugal distortion constants for the DCCCOOH···HOOCH and HCCCOOD···DOOCH isotopologues. Rotational transitions were measured in the frequency range of 4.9-15.4 GHz, providing accurate rotational constants, which, combined with previous rotational constants, allowed an improved structural fit for the propiolic acid-formic acid complex. The new structural fit yields reasonably accurate orientations for both the propiolic and formic acid monomers in the complex and more accurate structural parameters describing the hydrogen bonding. The structure is planar, with a positive inertial defect of Δ = 1.33 amu Å(2). The experimental structure exhibits a greater asymmetry for the two hydrogen bond lengths than was obtained from the ab initio mp2 calculations. The best-fit hydrogen bond lengths have an r(O1-H1···O4) of 1.64 Å and an r(O3-H2···O2) of 1.87 Å. The average of the two hydrogen bond lengths is r(av)(exp) = 1.76 Å, in good agreement with r(av)(theory) = 1.72 Å. The center of mass separation of the monomers is R(CM) = 3.864 Å. Other structural parameters from the least-squares fit using the experimental rotational constants are compared with theoretical values. The spectra were obtained using two different pulsed beam Fourier transform microwave spectrometers.

Structural and biophysical analysis of interactions between cod and human uracil-DNA N-glycosylase (UNG) and UNG inhibitor (Ugi)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Assefa, Netsanet Gizaw; Niiranen, Laila; University of Turku, FIN-20014 Turku

2014-08-01

A structural and biophysical study of the interactions between cod and human uracil-DNA N-glycosylase (UNG) and their inhibitor Ugi is presented. The stronger interaction between cod UNG and Ugi can be explained by a greater positive electrostatic surface potential. Uracil-DNA N-glycosylase from Atlantic cod (cUNG) shows cold-adapted features such as high catalytic efficiency, a low temperature optimum for activity and reduced thermal stability compared with its mesophilic homologue human UNG (hUNG). In order to understand the role of the enzyme–substrate interaction related to the cold-adapted properties, the structure of cUNG in complex with a bacteriophage encoded natural UNG inhibitor (Ugi)more » has been determined. The interaction has also been analyzed by isothermal titration calorimetry (ITC). The crystal structure of cUNG–Ugi was determined to a resolution of 1.9 Å with eight complexes in the asymmetric unit related through noncrystallographic symmetry. A comparison of the cUNG–Ugi complex with previously determined structures of UNG–Ugi shows that they are very similar, and confirmed the nucleotide-mimicking properties of Ugi. Biophysically, the interaction between cUNG and Ugi is very strong and shows a binding constant (K{sub b}) which is one order of magnitude larger than that for hUNG–Ugi. The binding of both cUNG and hUNG to Ugi was shown to be favoured by both enthalpic and entropic forces; however, the binding of cUNG to Ugi is mainly dominated by enthalpy, while the entropic term is dominant for hUNG. The observed differences in the binding properties may be explained by an overall greater positive electrostatic surface potential in the protein–Ugi interface of cUNG and the slightly more hydrophobic surface of hUNG.« less

Land use diversification and intensification on elk winter range in Greater Yellowstone: A framework and agenda for social-ecological research

USGS Publications Warehouse

Haggerty, Julia Hobson; Epstein, Kathleen; Stone, Michael; Cross, Paul

2018-01-01

Amenity migration describes the movement of peoples to rural landscapes and the transition toward tourism and recreation and away from production-oriented land uses (ranching, timber harvesting). The resulting mosaic of land uses and community structures has important consequences for wildlife and their management. This research note examines amenity-driven changes to social-ecological systems in the Greater Yellowstone Ecosystem, specifically in lower elevations that serve as winter habitat for elk. We present a research agenda informed by a preliminary and exploratory mixed-methods investigation: the creation of a “social-impact” index of land use change on elk winter range and a focus group with wildlife management experts. Our findings suggest that elk are encountering an increasingly diverse landscape with respect to land use, while new ownership patterns increase the complexity of social and community dynamics. These factors, in turn, contribute to increasing difficulty meeting wildlife management objectives. To deal with rising complexity across social and ecological landscapes of the Greater Yellowstone Ecosystem, future research will focus on property life cycle dynamics, as well as systems approaches.

Segmental Isotopic Labeling of Proteins for Nuclear Magnetic Resonance

PubMed Central

Dongsheng, Liu; Xu, Rong; Cowburn, David

2009-01-01

Nuclear Magnetic Resonance (NMR) spectroscopy has emerged as one of the principle techniques of structural biology. It is not only a powerful method for elucidating the 3D structures under near physiological conditions, but also a convenient method for studying protein-ligand interactions and protein dynamics. A major drawback of macromolecular NMR is its size limitation caused by slower tumbling rates and greater complexity of the spectra as size increases. Segmental isotopic labeling allows specific segment(s) within a protein to be selectively examined by NMR thus significantly reducing the spectral complexity for large proteins and allowing a variety of solution-based NMR strategies to be applied. Two related approaches are generally used in the segmental isotopic labeling of proteins: expressed protein ligation and protein trans-splicing. Here we describe the methodology and recent application of expressed protein ligation and protein trans-splicing for NMR structural studies of proteins and protein complexes. We also describe the protocol used in our lab for the segmental isotopic labeling of a 50 kDa protein Csk (C-terminal Src Kinase) using expressed protein ligation methods. PMID:19632474

Relative Importance of Coral Cover, Habitat Complexity and Diversity in Determining the Structure of Reef Fish Communities

PubMed Central

Komyakova, Valeriya; Munday, Philip L.; Jones, Geoffrey P.

2013-01-01

The structure of coral reef habitat has a pronounced influence on the diversity, composition and abundance of reef-associated fishes. However, the particular features of the habitat that are most critical are not always known. Coral habitats can vary in many characteristics, notably live coral cover, topographic complexity and coral diversity, but the relative effects of these habitat characteristics are often not distinguished. Here, we investigate the strength of the relationships between these habitat features and local fish diversity, abundance and community structure in the lagoon of Lizard Island, Great Barrier Reef. In a spatial comparison using sixty-six 2m2 quadrats, fish species richness, total abundance and community structure were examined in relation to a wide range of habitat variables, including topographic complexity, habitat diversity, coral diversity, coral species richness, hard coral cover, branching coral cover and the cover of corymbose corals. Fish species richness and total abundance were strongly associated with coral species richness and cover, but only weakly associated with topographic complexity. Regression tree analysis showed that coral species richness accounted for most of the variation in fish species richness (63.6%), while hard coral cover explained more variation in total fish abundance (17.4%), than any other variable. In contrast, topographic complexity accounted for little spatial variation in reef fish assemblages. In degrading coral reef environments, the potential effects of loss of coral cover and topographic complexity are often emphasized, but these findings suggest that reduced coral biodiversity may ultimately have an equal, or greater, impact on reef-associated fish communities. PMID:24349455

Relative importance of coral cover, habitat complexity and diversity in determining the structure of reef fish communities.

PubMed

Komyakova, Valeriya; Munday, Philip L; Jones, Geoffrey P

2013-01-01

The structure of coral reef habitat has a pronounced influence on the diversity, composition and abundance of reef-associated fishes. However, the particular features of the habitat that are most critical are not always known. Coral habitats can vary in many characteristics, notably live coral cover, topographic complexity and coral diversity, but the relative effects of these habitat characteristics are often not distinguished. Here, we investigate the strength of the relationships between these habitat features and local fish diversity, abundance and community structure in the lagoon of Lizard Island, Great Barrier Reef. In a spatial comparison using sixty-six 2m(2) quadrats, fish species richness, total abundance and community structure were examined in relation to a wide range of habitat variables, including topographic complexity, habitat diversity, coral diversity, coral species richness, hard coral cover, branching coral cover and the cover of corymbose corals. Fish species richness and total abundance were strongly associated with coral species richness and cover, but only weakly associated with topographic complexity. Regression tree analysis showed that coral species richness accounted for most of the variation in fish species richness (63.6%), while hard coral cover explained more variation in total fish abundance (17.4%), than any other variable. In contrast, topographic complexity accounted for little spatial variation in reef fish assemblages. In degrading coral reef environments, the potential effects of loss of coral cover and topographic complexity are often emphasized, but these findings suggest that reduced coral biodiversity may ultimately have an equal, or greater, impact on reef-associated fish communities.

A porphyrin complex of Gold(I): (Phosphine)gold(I) azides as cation precursors

PubMed Central

Partyka, David V.; Robilotto, Thomas J.; Zeller, Matthias; Hunter, Allen D.; Gray, Thomas G.

2008-01-01

A silver- and Brönsted acid-free protocol for generating the (tricyclohexylphosphine)gold(I) cation from the corresponding azide complexes is disclosed. The gold(I) cations so liberated are trapped by complexation with octaethylporphyrin. The first structurally authenticated gold(I) porphyrin complex crystallizes with formula C72H112Au2F12N4P2Sb2, space group C2/c, a = 21.388 (4), b = 19.679 (4), c = 19.231 (3) Å; β = 111.030 (3)°. Solution spectroscopic studies indicate that the di-gold complex fragments on dissolution in organic solvents. Approximate density-functional theory calculations find an electrostatic origin for the binding of two gold(I) centers to the unprotonated nitrogen atoms, despite greater orbital density on the porphyrin meso carbons. PMID:18780788

Ecologically Enhancing Coastal Infrastructure

NASA Astrophysics Data System (ADS)

Mac Arthur, Mairi; Naylor, Larissa; Hansom, Jim; Burrows, Mike; Boyd, Ian

2017-04-01

Hard engineering structures continue to proliferate in the coastal zone globally in response to increasing pressures associated with rising sea levels, coastal flooding and erosion. These structures are typically plain-cast by design and function as poor ecological surrogates for natural rocky shores which are highly topographically complex and host a range of available microhabitats for intertidal species. Ecological enhancement mitigates some of these negative impacts by integrating components of nature into the construction and design of these structures to improve their sustainability, resilience and multifunctionality. In the largest UK ecological enhancement trial to date, 184 tiles (15x15cm) of up to nine potential designs were deployed on vertical concrete coastal infrastructure in 2016 at three sites across the UK (Saltcoats, Blackness and Isle of Wight). The surface texture and complexity of the tiles were varied to test the effect of settlement surface texture at the mm-cm scale of enhancement on the success of colonisation and biodiversity in the mid-upper intertidal zone in order to answer the following experimental hypotheses: • Tiles with mm-scale geomorphic complexity will have greater barnacle abundances • Tiles with cm-scale geomorphic complexity will have greater species richness than mm-scale tiles. A range of methods were used in creating the tile designs including terrestrial laser scanning of creviced rock surfaces to mimic natural rocky shore complexity as well as artificially generated complexity using computer software. The designs replicated the topographic features of high ecological importance found on natural rocky shores and promoted species recruitment and community composition on artificial surfaces; thus enabling us to evaluate biological responses to geomorphic complexity in a controlled field trial. At two of the sites, the roughest tile designs (cm scale) did not have the highest levels of barnacle recruits which were instead counted on tiles of intermediate roughness such as the grooved concrete with 257 recruits on average (n=8) at four months' post-installation (Saltcoats) and 1291 recruits at two months' post-installation (Isle of Wight). This indicates that a higher level of complexity does not always reflect the most appropriate roughness scale for some colonisers. On average, tiles with mm scale texture were more successful in terms of barnacle colonisation compared to plain-cast control tiles (n=8 per site). The poor performance of the control tiles (9 recruits, Saltcoats; 147 recruits, Isle of Wight after 4 and 2 months, respectively) further highlights that artificial, hard substrates are poor ecological surrogates for natural rocky shores. One of the sites, Blackness, was an observed outlier to the general trend of colonisation, likely due to its estuarine location. This factor may contribute to why every design, including the control tile, had high abundances of barnacles. Artificially designed tiles with cm-scale complexity had higher levels of species richness, with periwinkles and topshells frequently observed to utilise the tile microhabitats in greater numbers than found on other tile designs. These results show that the scale of geomorphic complexity influences early stage colonisation. Data analysis is being carried out between now and the EGU - these advanced analyses would be presented.

Effectiveness of Matrix Organizations at the TACOM LCMC

DTIC Science & Technology

2013-04-05

Scott Baumgartner UNCLASSIFIED 14 responsibility and involvement in decision making, and offers a greater opportunity to display capabilities and...According to Knight, “Matrix structures are said to facilitate high quality and innovative solutions to complex technical problems” (Knight, 1976...discipline expertise to remain innovative (Davis & Lawrence, 1977). Communications The project teams must have a clear understanding of the vision, goals

Auditory sensitivity of seals and sea lions in complex listening scenarios.

PubMed

Cunningham, Kane A; Southall, Brandon L; Reichmuth, Colleen

2014-12-01

Standard audiometric data, such as audiograms and critical ratios, are often used to inform marine mammal noise-exposure criteria. However, these measurements are obtained using simple, artificial stimuli-i.e., pure tones and flat-spectrum noise-while natural sounds typically have more complex structure. In this study, detection thresholds for complex signals were measured in (I) quiet and (II) masked conditions for one California sea lion (Zalophus californianus) and one harbor seal (Phoca vitulina). In Experiment I, detection thresholds in quiet conditions were obtained for complex signals designed to isolate three common features of natural sounds: Frequency modulation, amplitude modulation, and harmonic structure. In Experiment II, detection thresholds were obtained for the same complex signals embedded in two types of masking noise: Synthetic flat-spectrum noise and recorded shipping noise. To evaluate how accurately standard hearing data predict detection of complex sounds, the results of Experiments I and II were compared to predictions based on subject audiograms and critical ratios combined with a basic hearing model. Both subjects exhibited greater-than-predicted sensitivity to harmonic signals in quiet and masked conditions, as well as to frequency-modulated signals in masked conditions. These differences indicate that the complex features of naturally occurring sounds enhance detectability relative to simple stimuli.

Characterization of U(VI)-carbonato ternary complexes on hematite: EXAFS and electrophoretic mobility measurements

USGS Publications Warehouse

Bargar, John R.; Reitmeyer, Rebecca; Lenhart, John J.; Davis, James A.

2000-01-01

We have measured U(VI) adsorption on hematite using EXAFS spectroscopy and electrophoresis under conditions relevant to surface waters and aquifers (0.01 to 10 μM dissolved uranium concentrations, in equilibrium with air, pH 4.5 to 8.5). Both techniques suggest the existence of anionic U(VI)-carbonato ternary complexes. Fits to EXAFS spectra indicate that U(VI) is simultaneously coordinated to surface FeO6 octahedra and carbonate (or bicarbonate) ligands in bidentate fashions, leading to the conclusion that the ternary complexes have an inner-sphere metal bridging (hematite-U(VI)-carbonato) structure. Greater than or equal to 50% of adsorbed U(VI) was comprised of monomeric hematite-U(VI)-carbonato ternary complexes, even at pH 4.5. Multimeric U(VI) species were observed at pH ≥ 6.5 and aqueous U(VI) concentrations approximately an order of magnitude more dilute than the solubility of crystalline β-UO2(OH)2. Based on structural constraints, these complexes were interpreted as dimeric hematite-U(VI)-carbonato ternary complexes. These results suggest that Fe-oxide-U(VI)-carbonato complexes are likely to be important transport-limiting species in oxic aquifers throughout a wide range of pH values.

Legacy of Pre-Disturbance Spatial Pattern Determines Early Structural Diversity following Severe Disturbance in Montane Spruce Forests

PubMed Central

Bače, Radek; Svoboda, Miroslav; Janda, Pavel; Morrissey, Robert C.; Wild, Jan; Clear, Jennifer L.; Čada, Vojtěch; Donato, Daniel C.

2015-01-01

Background Severe canopy-removing disturbances are native to many temperate forests and radically alter stand structure, but biotic legacies (surviving elements or patterns) can lend continuity to ecosystem function after such events. Poorly understood is the degree to which the structural complexity of an old-growth forest carries over to the next stand. We asked how pre-disturbance spatial pattern acts as a legacy to influence post-disturbance stand structure, and how this legacy influences the structural diversity within the early-seral stand. Methods Two stem-mapped one-hectare forest plots in the Czech Republic experienced a severe bark beetle outbreak, thus providing before-and-after data on spatial patterns in live and dead trees, crown projections, down logs, and herb cover. Results Post-disturbance stands were dominated by an advanced regeneration layer present before the disturbance. Both major species, Norway spruce (Picea abies) and rowan (Sorbus aucuparia), were strongly self-aggregated and also clustered to former canopy trees, pre-disturbance snags, stumps and logs, suggesting positive overstory to understory neighbourhood effects. Thus, although the disturbance dramatically reduced the stand’s height profile with ~100% mortality of the canopy layer, the spatial structure of post-disturbance stands still closely reflected the pre-disturbance structure. The former upper tree layer influenced advanced regeneration through microsite and light limitation. Under formerly dense canopies, regeneration density was high but relatively homogeneous in height; while in former small gaps with greater herb cover, regeneration density was lower but with greater heterogeneity in heights. Conclusion These findings suggest that pre-disturbance spatial patterns of forests can persist through severe canopy-removing disturbance, and determine the spatial structure of the succeeding stand. Such patterns constitute a subtle but key legacy effect, promoting structural complexity in early-seral forests as well as variable successional pathways and rates. This influence suggests a continuity in spatial ecosystem structure that may well persist through multiple forest generations. PMID:26421726

Novel copper(II) complexes as new promising antitumour agents. A crystal structure of [Cu(1,10-phenanthroline-5,6-dione)2(OH2)(OClO3)](ClO4).

PubMed

Pivetta, Tiziana; Trudu, Federica; Valletta, Elisa; Isaia, Francesco; Castellano, Carlo; Demartin, Francesco; Tuveri, Rossana; Vascellari, Sarah; Pani, Alessandra

2014-12-01

The cytotoxic properties of copper(II) complexes with 1,10-phenanthroline (phen) can be modified by substitution in the phen backbone. For this purpose, Cu(II) complexes with phen, 1,10-phenanthrolin-5,6-dione (phendione) and 1,10-phenanthrolin-5,6-diol (phendiol) have been synthesised and characterised. The crystal structure of [Cu(phendione)2(OH2)(OClO3)](ClO4) is discussed. The complex formation equilibria between Cu(II) and phen or phendione were studied by potentiometric measurements at 25 and 37°C in 0.1 M ionic strength (NaCl). The antitumour activity of the compounds has been tested in vitro against a panel of tumour (DU-145, HEP-G2, SK-MES-1, CCRF-CEM, CCRF-SB) and normal (CRL-7065) human cell lines. The studied compounds generally present an antiproliferative effect greater than that of cisplatin. The phen and phendione ligands present a similar antiproliferative effect against all the tested cells. Phendiol presents an antiproliferative effect 1.3 to 18 times greater than that of phen or phendione for leukemic, lung, prostatic and fibroblast cells, while it presents less activity towards hepatic cells. Complexes with two ligands are more cytotoxic towards all the tested cell lines than complexes with one ligand and are generally more cytotoxic than the ligand alone. Complexes [Cu(phendiol)2(OH2)](ClO4)2 and [Cu(phendione)2(OH2)(OClO3)](ClO4) appear to be the most active compounds for the treatment of SK-MES-1 and HEP-G2 cells, respectively, being at least 18 times more cytotoxic than cisplatin. The studied Cu(II) complexes are characterised by a strong DNA affinity and were found to interact with DNA mainly by groove binding or electrostatic interactions. The complexes appear to act on cells with a mechanism different from that of cisplatin. Copyright © 2014 Elsevier Inc. All rights reserved.

Ortho-para interconversion in cation-water complexes: The case of V + (H 2 O) and Nb + (H 2 O) clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, T. B.; Miliordos, E.; Carnegie, P. D.

Vanadium and niobium cation-water complexes, V+(H2O) and Nb+(H2O), are produced by laser vaporization in a pulsed supersonic expansion, mass selected in a time-of-flight spectrometer, and studied with infrared photodissociation spectroscopy using rare gas atom (Ar, Ne) complex predissociation. The vibrational bands measured in the O–H stretching region contain K-type rotational sub-band structure, which provides insight into the structures of these complexes. However, rotational sub-bands do not exhibit the simple patterns seen previously for other metal ion-water complexes. The A rotational constants are smaller than expected and the normal 1:3 intensity ratios for K = even:odd levels for independent ortho:para nuclearmore » spin states are missing for some complexes. We relied on highly correlated internally contracted Multi-Reference Configuration Interaction (icMRCI) and Coupled Cluster [CCSD(T)] electronic structure calculations of those complexes with and without the rare gas atoms to investigate these anomalies. Rare gas atoms were found to bind via asymmetric motifs to the hydrated complexes undergoing large amplitude motions that vibrationally average to quasi-C2v symmetry with significant probability off the C2 axis, thus explaining the reduced A values. Both vanadium and iobium cations exhibit unusually strong nuclear spin coupling to the hydrogen atoms of water, the values of which vary with their electronic state. This catalyzes ortho-para interconversion in some complexes and explains the rotational patterns. The rate of ortho-para relaxation in the equilibrated complexes must therefore be greater than the collisional cooling rate in the supersonic expansion (about 106 sec-1).« less

Ortho-para interconversion in cation-water complexes: The case of V+(H2O) and Nb+(H2O) clusters.

PubMed

Ward, T B; Miliordos, E; Carnegie, P D; Xantheas, S S; Duncan, M A

2017-06-14

Vanadium and niobium cation-water complexes, V + (H 2 O) and Nb + (H 2 O), are produced by laser vaporization in a pulsed supersonic expansion, mass selected in a time-of-flight spectrometer, and studied with infrared photodissociation spectroscopy using rare gas atom (Ar, Ne) complex predissociation. The vibrational bands measured in the O-H stretching region contain K-type rotational sub-band structure, which provides insight into the structures of these complexes. However, rotational sub-bands do not exhibit the simple patterns seen previously for other metal ion-water complexes. The A rotational constants are smaller than expected and the normal 3:1 intensity ratios for K = odd:even levels for independent ortho:para nuclear spin states are missing for some complexes. We relied on highly correlated internally contracted multi-reference configuration interaction and Coupled Cluster [CCSD(T)] electronic structure calculations of those complexes with and without the rare gas atoms to investigate these anomalies. Rare gas atoms were found to bind via asymmetric motifs to the hydrated complexes undergoing large amplitude motions that vibrationally average to the quasi-C 2v symmetry with a significant probability off the C 2 axis, thus explaining the reduced A values. Both vanadium and niobium cations exhibit unusually strong nuclear spin coupling to the hydrogen atoms of water, the values of which vary with their electronic state. This catalyzes ortho-para interconversion in some complexes and explains the rotational patterns. The rate of ortho-para relaxation in the equilibrated complexes must therefore be greater than the collisional cooling rate in the supersonic expansion (about 10 6 s -1 ).

Ortho-para interconversion in cation-water complexes: The case of V+(H2O) and Nb+(H2O) clusters

NASA Astrophysics Data System (ADS)

Ward, T. B.; Miliordos, E.; Carnegie, P. D.; Xantheas, S. S.; Duncan, M. A.

2017-06-01

Vanadium and niobium cation-water complexes, V+(H2O) and Nb+(H2O), are produced by laser vaporization in a pulsed supersonic expansion, mass selected in a time-of-flight spectrometer, and studied with infrared photodissociation spectroscopy using rare gas atom (Ar, Ne) complex predissociation. The vibrational bands measured in the O-H stretching region contain K-type rotational sub-band structure, which provides insight into the structures of these complexes. However, rotational sub-bands do not exhibit the simple patterns seen previously for other metal ion-water complexes. The A rotational constants are smaller than expected and the normal 3:1 intensity ratios for K = odd:even levels for independent ortho:para nuclear spin states are missing for some complexes. We relied on highly correlated internally contracted multi-reference configuration interaction and Coupled Cluster [CCSD(T)] electronic structure calculations of those complexes with and without the rare gas atoms to investigate these anomalies. Rare gas atoms were found to bind via asymmetric motifs to the hydrated complexes undergoing large amplitude motions that vibrationally average to the quasi-C2v symmetry with a significant probability off the C2 axis, thus explaining the reduced A values. Both vanadium and niobium cations exhibit unusually strong nuclear spin coupling to the hydrogen atoms of water, the values of which vary with their electronic state. This catalyzes ortho-para interconversion in some complexes and explains the rotational patterns. The rate of ortho-para relaxation in the equilibrated complexes must therefore be greater than the collisional cooling rate in the supersonic expansion (about 106 s-1).

Structural plasticity: how intermetallics deform themselves in response to chemical pressure, and the complex structures that result.

PubMed

Berns, Veronica M; Fredrickson, Daniel C

2014-10-06

Interfaces between periodic domains play a crucial role in the properties of metallic materials, as is vividly illustrated by the way in which the familiar malleability of many metals arises from the formation and migration of dislocations. In complex intermetallics, such interfaces can occur as an integral part of the ground-state crystal structure, rather than as defects, resulting in such marvels as the NaCd2 structure (whose giant cubic unit cell contains more than 1000 atoms). However, the sources of the periodic interfaces in intermetallics remain mysterious, unlike the dislocations in simple metals, which can be associated with the exertion of physical stresses. In this Article, we propose and explore the concept of structural plasticity, the hypothesis that interfaces in complex intermetallic structures similarly result from stresses, but ones that are inherent in a defect-free parent structure, rather than being externally applied. Using DFT-chemical pressure analysis, we show how the complex structures of Ca2Ag7 (Yb2Ag7 type), Ca14Cd51 (Gd14Ag51 type), and the 1/1 Tsai-type quasicrystal approximant CaCd6 (YCd6 type) can all be traced to large negative pressures around the Ca atoms of a common progenitor structure, the CaCu5 type with its simple hexagonal 6-atom unit cell. Two structural paths are found by which the compounds provide relief to the Ca atoms' negative pressures: a Ca-rich pathway, where lower coordination numbers are achieved through defects eliminating transition metal (TM) atoms from the structure; and a TM-rich path, along which the addition of spacer Cd atoms provides the Ca coordination environments greater independence from each other as they contract. The common origins of these structures in the presence of stresses within a single parent structure highlights the diverse paths by which intermetallics can cope with competing interactions, and the role that structural plasticity may play in navigating this diversity.

Structural deformation upon protein-protein interaction: A structural alphabet approach

PubMed Central

Martin, Juliette; Regad, Leslie; Lecornet, Hélène; Camproux, Anne-Claude

2008-01-01

Background In a number of protein-protein complexes, the 3D structures of bound and unbound partners significantly differ, supporting the induced fit hypothesis for protein-protein binding. Results In this study, we explore the induced fit modifications on a set of 124 proteins available in both bound and unbound forms, in terms of local structure. The local structure is described thanks to a structural alphabet of 27 structural letters that allows a detailed description of the backbone. Using a control set to distinguish induced fit from experimental error and natural protein flexibility, we show that the fraction of structural letters modified upon binding is significantly greater than in the control set (36% versus 28%). This proportion is even greater in the interface regions (41%). Interface regions preferentially involve coils. Our analysis further reveals that some structural letters in coil are not favored in the interface. We show that certain structural letters in coil are particularly subject to modifications at the interface, and that the severity of structural change also varies. These information are used to derive a structural letter substitution matrix that summarizes the local structural changes observed in our data set. We also illustrate the usefulness of our approach to identify common binding motifs in unrelated proteins. Conclusion Our study provides qualitative information about induced fit. These results could be of help for flexible docking. PMID:18307769

Structural deformation upon protein-protein interaction: a structural alphabet approach.

PubMed

Martin, Juliette; Regad, Leslie; Lecornet, Hélène; Camproux, Anne-Claude

2008-02-28

In a number of protein-protein complexes, the 3D structures of bound and unbound partners significantly differ, supporting the induced fit hypothesis for protein-protein binding. In this study, we explore the induced fit modifications on a set of 124 proteins available in both bound and unbound forms, in terms of local structure. The local structure is described thanks to a structural alphabet of 27 structural letters that allows a detailed description of the backbone. Using a control set to distinguish induced fit from experimental error and natural protein flexibility, we show that the fraction of structural letters modified upon binding is significantly greater than in the control set (36% versus 28%). This proportion is even greater in the interface regions (41%). Interface regions preferentially involve coils. Our analysis further reveals that some structural letters in coil are not favored in the interface. We show that certain structural letters in coil are particularly subject to modifications at the interface, and that the severity of structural change also varies. These information are used to derive a structural letter substitution matrix that summarizes the local structural changes observed in our data set. We also illustrate the usefulness of our approach to identify common binding motifs in unrelated proteins. Our study provides qualitative information about induced fit. These results could be of help for flexible docking.

Developmental instability of gynodioecious Teucrium lusitanicum

USGS Publications Warehouse

Alados, C.L.; Navarro, T.; Cabezudo, B.; Emlen, J.M.; Freeman, C.

1998-01-01

Developmental instability was assessed in two geographical races of Teucrium lusitanicum using morphometric measures of vegetative and reproductive structures. T. lusitanicum is a gynodioecious species. Male sterile (female) individuals showed greater developmental instability at all sites. Plants located inland had higher developmental instability of vegetative characters and lower developmental instability of reproductive characters than coastal plants. These results support the contentions that (1) developmental instability is affected more by the disruption of co-adapted gene complexes than by lower heterozygosity, and (2) different habitat characteristics result in the differential response of vegetative and reproductive structures.

The problem of the age and structural position of the Blyb metamorphic complex (Fore Range zone, Great Caucasus) granitoids.

NASA Astrophysics Data System (ADS)

Kamzolkin, Vladimir; Latyshev, Anton; Ivanov, Stanislav

2016-04-01

The Blyb metamorphic complex (BMC) of the Fore Range zone is one of the most high-grade metamorphosed element of the Great Caucasus fold belt. Determination of the timing and the mechanism of formation of the Fore Range fold-thrust structures are not possible without investigation of the BMC located at the basement of its section. At the same time, the conceptions about its structure and age are outdated and need revision. Somin (2011) determined the age of the protolith and metamorphism of the Blyb complex as the Late Devonian - Early Carboniferous. We have recently shown that the BMC has not the dome, as previously thought, but nappe structure (Vidjapin, Kamzolkin, 2015), and is metamorphically coherent with the peak metamorphism pressures up to 22 kbar (Kamzolkin et al., 2015; Konilov et al., 2013). Considering the age and structure of the Blyb complex it is necessary to revise the age of granitoid intrusions and their relations with gneisses and schists, which constitute the main part of the section of the complex. Most authors (Gamkrelidze, Shengelia, 2007; Lavrischev, 2002; Baranov, 1967) adheres to Early Paleozoic age of intrusives, which is doubtful, considering the younger age of metamorphic rocks. We suppose, that the intrusive bodies broke through a BMC nappe structure during the exhumation of the complex (Perchuk, 1991) at the Devonian - Carboniferous boundary. Seemingly, the massive monzodiorites body (Lavrischev, 2002), intruding garnet-muscovite schists and amphibolite gneisses of the Blyb complex and cut by the Main Caucasian fault (MCF), are younger. Given the timing of termination of the MCF movement activity as the Middle Jurassic (Greater Caucasus..., 2005), their age should be in the Early Carboniferous - Middle Jurassic interval. At the same time, on the modern geological map (Lavrischev, 2002) monzodiorites body is assigned to the Middle Paleozoic. The study of the BMC granitoids and monzodiorites will help in determining of the mechanism and age of exhumation of the Blyb metamorphic complex high-pressure rocks. The reported study was partially supported by RFBR, research projects No. 16-35-00571mol_a; 16-05-01012a

Hippocampus in health and disease: An overview

PubMed Central

Anand, Kuljeet Singh; Dhikav, Vikas

2012-01-01

Hippocampus is a complex brain structure embedded deep into temporal lobe. It has a major role in learning and memory. It is a plastic and vulnerable structure that gets damaged by a variety of stimuli. Studies have shown that it also gets affected in a variety of neurological and psychiatric disorders. In last decade or so, lot has been learnt about conditions that affect hippocampus and produce changes ranging from molecules to morphology. Progresses in radiological delineation, electrophysiology, and histochemical characterization have made it possible to study this archicerebral structure in greater detail. Present paper attempts to give an overview of hippocampus, both in health and diseases. PMID:23349586

Quantifying Mass Transfer Processes in Groundwater as a Function of Molecular Structure Variation for Multicomponent NAPL Sources

NASA Astrophysics Data System (ADS)

Abbott, J. B., III; Tick, G. R.; Greenberg, R. R.; Carroll, K. C.

2017-12-01

The remediation of nonaqueous liquid (NAPL) contamination sources in groundwater has been shown to be challenging and have limited success in the field. The presence of multicomponent NAPL sources further complicates the remediation due to variability of mass-transfer (dissolution) behavior as a result of compositional and molecular structure variations between the different compounds within the NAPL phase. This study investigates the effects of the contaminant of concern (COC) composition and the bulk-NAPL components molecular structure (i.e. carbon chain length, aliphatic and aromatic) on dissolution and aqueous phase concentrations in groundwater. The specific COCs tested include trichloroethene (TCE), toluene (TOL), and perfluorooctanoic acid (PFOA). Each COC was tested in a series of binary batch experiments using insoluble bulk NAPL including n-hexane (HEX), n-decane (DEC), and n-hexadecane (HEXDEC). These equilibrium batch tests were performed to understand how different carbon-chain-length (NAPL) systems affect resulting COC aqueous phase concentrations. The experiments were conducted with four different COC mole fractions mixed within the bulk-NAPL derivatives (0.1:0.9, 0.05:0.95, 0.01:0.99, 0.001:0.999). Raoult's Law was used to assess the relative ideality of the mass transfer processes for each binary equilibrium dissolution experiment. Preliminary results indicate that as mole fraction of the COC decreases (composition effects), greater deviance from dissolution ideality occurs. It was also shown that greater variation in molecular structure (i.e. greater carbon chain length of bulk-NAPL with COC and aromatic COC presence) exhibited greater dissolution nonideality via Raoult's Law analysis. For instance, TOL (aromatic structure) showed greater nonideality than TCE (aliphatic structure) in the presence of the different bulk-NAPL derivatives (i.e. of various aliphatic carbon chains lengths). The results suggest that the prediction of aqueous phase concentration, from complex multicomponent NAPL sources, is highly dependent upon both composition and molecular structure variations of COC-NAPL mixtures, and such impacts should be taken into account when designing and evaluating a remediation strategy and/or predicting COC concentrations from a source zone region.

Accountability in the UK Healthcare System: An Overview

PubMed Central

Peckham, Stephen

2014-01-01

Recent changes in the English National Health Service (NHS) have introduced new complexities into the accountability arrangements for healthcare services. This commentary describes how the new organizational structures have challenged the traditional centralized accountability structures by creating a more dispersed system of governance for local health-care commissioners. It sets the context of discussions about accountability in the UK NHS and then describes the key changes in England following the implementation of the NHS reforms in April 2013. The commentary concludes that while there is increased complexity of accountability within a more decentralized and fragmented healthcare system, the government's goal of achieving increased local autonomy and greater control by general practitioners (GPs) will probably not be realized. In particular, the system will continue to have strongly centralized aspects, with increased regulation and central political responsibility. PMID:25305399

Hierarchical temporal structure in music, speech and animal vocalizations: jazz is like a conversation, humpbacks sing like hermit thrushes.

PubMed

Kello, Christopher T; Bella, Simone Dalla; Médé, Butovens; Balasubramaniam, Ramesh

2017-10-01

Humans talk, sing and play music. Some species of birds and whales sing long and complex songs. All these behaviours and sounds exhibit hierarchical structure-syllables and notes are positioned within words and musical phrases, words and motives in sentences and musical phrases, and so on. We developed a new method to measure and compare hierarchical temporal structures in speech, song and music. The method identifies temporal events as peaks in the sound amplitude envelope, and quantifies event clustering across a range of timescales using Allan factor (AF) variance. AF variances were analysed and compared for over 200 different recordings from more than 16 different categories of signals, including recordings of speech in different contexts and languages, musical compositions and performances from different genres. Non-human vocalizations from two bird species and two types of marine mammals were also analysed for comparison. The resulting patterns of AF variance across timescales were distinct to each of four natural categories of complex sound: speech, popular music, classical music and complex animal vocalizations. Comparisons within and across categories indicated that nested clustering in longer timescales was more prominent when prosodic variation was greater, and when sounds came from interactions among individuals, including interactions between speakers, musicians, and even killer whales. Nested clustering also was more prominent for music compared with speech, and reflected beat structure for popular music and self-similarity across timescales for classical music. In summary, hierarchical temporal structures reflect the behavioural and social processes underlying complex vocalizations and musical performances. © 2017 The Author(s).

Multiscale modelling of hydraulic conductivity in vuggy porous media

PubMed Central

Daly, K. R.; Roose, T.

2014-01-01

Flow in both saturated and non-saturated vuggy porous media, i.e. soil, is inherently multiscale. The complex microporous structure of the soil aggregates and the wider vugs provides a multitude of flow pathways and has received significant attention from the X-ray computed tomography (CT) community with a constant drive to image at higher resolution. Using multiscale homogenization, we derive averaged equations to study the effects of the microscale structure on the macroscopic flow. The averaged model captures the underlying geometry through a series of cell problems and is verified through direct comparison to numerical simulations of the full structure. These methods offer significant reductions in computation time and allow us to perform three-dimensional calculations with complex geometries on a desktop PC. The results show that the surface roughness of the aggregate has a significantly greater effect on the flow than the microstructure within the aggregate. Hence, this is the region in which the resolution of X-ray CT for image-based modelling has the greatest impact. PMID:24511248

Structural and thermodynamic properties of the Cm III ion solvated by water and methanol

DOE PAGES

Kelley, Morgan P.; Yang, Ping; Clark, Sue B.; ...

2016-04-27

The geometric and electronic structures of the 9-coordinate Cm 3+ ion solvated with both water and methanol are systematically investigated in the gas phase at each possible solvent-shell composition and configuration using density functional theory and second-order Møller–Plesset perturbation theory. Ab initio molecular dynamics simulations are employed to assess the effects of second and third solvent shells on the gas-phase structure. The ion–solvent dissociation energy for methanol is greater than that of water, potentially because of increased charge donation to the ion made possible by the electron-rich methyl group. Further, the ion–solvent dissociation energy and the ion–solvent distance are shownmore » to be dependent on the solvent-shell composition. Furthermore, this has implications for solvent exchange, which is generally the rate-limiting step in complexation reactions utilized in the separation of curium from complex metal mixtures that derive from the advanced nuclear fuel cycle.« less

Crystallographic structure of a small molecule SIRT1 activator-enzyme complex

NASA Astrophysics Data System (ADS)

Dai, Han; Case, April W.; Riera, Thomas V.; Considine, Thomas; Lee, Jessica E.; Hamuro, Yoshitomo; Zhao, Huizhen; Jiang, Yong; Sweitzer, Sharon M.; Pietrak, Beth; Schwartz, Benjamin; Blum, Charles A.; Disch, Jeremy S.; Caldwell, Richard; Szczepankiewicz, Bruce; Oalmann, Christopher; Yee Ng, Pui; White, Brian H.; Casaubon, Rebecca; Narayan, Radha; Koppetsch, Karsten; Bourbonais, Francis; Wu, Bo; Wang, Junfeng; Qian, Dongming; Jiang, Fan; Mao, Cheney; Wang, Minghui; Hu, Erding; Wu, Joe C.; Perni, Robert B.; Vlasuk, George P.; Ellis, James L.

2015-07-01

SIRT1, the founding member of the mammalian family of seven NAD+-dependent sirtuins, is composed of 747 amino acids forming a catalytic domain and extended N- and C-terminal regions. We report the design and characterization of an engineered human SIRT1 construct (mini-hSIRT1) containing the minimal structural elements required for lysine deacetylation and catalytic activation by small molecule sirtuin-activating compounds (STACs). Using this construct, we solved the crystal structure of a mini-hSIRT1-STAC complex, which revealed the STAC-binding site within the N-terminal domain of hSIRT1. Together with hydrogen-deuterium exchange mass spectrometry (HDX-MS) and site-directed mutagenesis using full-length hSIRT1, these data establish a specific STAC-binding site and identify key intermolecular interactions with hSIRT1. The determination of the interface governing the binding of STACs with human SIRT1 facilitates greater understanding of STAC activation of this enzyme, which holds significant promise as a therapeutic target for multiple human diseases.

Healthy coral reefs may assure coastal protection in face of climate change related sea level rise

NASA Astrophysics Data System (ADS)

Harris, D. L.; Rovere, A.; Parravicini, V.; Casella, E.; Canavesio, R.; Collin, A.

2016-12-01

Coral reefs are diverse ecosystems that support millions of people worldwide providing crucial services, of which, coastal protection is one of the most relevant. The efficiency of coral reefs in protecting coastlines and dissipating waves is directly linked to the cover of living corals and three dimensional reef structural complexity. Climate change and human impacts are leading to severe global reductions in live coral cover, posing serious concerns regarding the capacity of degraded reef systems in protecting tropical coastal regions. Although it is known that the loss of structurally complex reefs may lead to greater erosion of coastlines, this process has rarely been quantified and it is still unknown whether the maintenance of healthy reefs through conservation will be enough to guarantee coastal protection during rising sea levels. We show that a significant loss of wave dissipation and a subsequent increase in back-reef wave height (up to 5 times present wave height) could occur even at present sea level if living corals are lost and reef structural complexity is reduced. Yet we also show that healthy reefs, measured by structural complexity and efficiency of vertical reef accretion, may maintain their present capacity of wave dissipation even under rising sea levels. Our results indicate that the health of coral reefs and not sea level rise will be the major determinant of the coastal protection services provided by coral reefs and calls for investments into coral reef conservation to ensure the future protection of tropical coastal communities.

Complex fold and thrust belt structural styles: Examples from the Greater Juha area of the Papuan Fold and Thrust Belt, Papua New Guinea

NASA Astrophysics Data System (ADS)

Mahoney, Luke; Hill, Kevin; McLaren, Sandra; Hanani, Amanda

2017-07-01

The remote and inhospitable Papuan Fold Belt in Papua New Guinea is one of the youngest yet least well-documented fold and thrust belts on Earth. Within the frontal Greater Juha area we have carried out >100 km of geological traverses and associated analyses that have added significantly to the contemporary geological and geophysical dataset. Our structural analysis provides evidence of major inversion, detachment and triangle zone faults within the uplifted Eastern Muller Ranges. We have used the dataset to develop a quasi-3D model for the Greater Juha area, with associated cross-sections revealing that the exposed Cenozoic Darai Limestone is well-constrained with very low shortening of 12.6-21.4% yet structures are elevated up to 7 km above regional. We suggest the inversion of pre-existing rift architecture is the primary influence on the evolution of the area and that structures link to the surface via triangle zones and detachment faults within the incompetent Mesozoic passive-margin sedimentary sequence underlying competent Darai Limestone. Arc-normal oriented structures, dominantly oblique dextral, up-to-the-southeast, are pervasive across a range of scales and are here interpreted to relate at depth to weakened pre-existing basement cross-structures. It is proposed that Palaeozoic basement fabric controlled the structural framework of the basin during Early Mesozoic rifting forming regional-scale accommodation zones and related local-scale transfer structures that are now expressed as regional-scale arc-normal lineaments and local-scale arc-normal structures, respectively. Transfer structures, including complexly breached relay ramps, utilise northeast-southwest striking weaknesses associated with the basement fabric, as a mechanism for accommodating displacement along major northwest-southeast striking normal faults. These structures have subsequently been inverted to form arc-normal oriented zones of tear faulting that accommodate laterally variable displacement along inversion faults and connected thrust structures.

Neutrons for biologists: a beginner's guide, or why you should consider using neutrons.

PubMed

Lakey, Jeremy H

2009-10-06

From the structures of isolated protein complexes to the molecular dynamics of whole cells, neutron methods can achieve a resolution in complex systems that is inaccessible to other techniques. Biology is fortunate in that it is rich in water and hydrogen, and this allows us to exploit the differential sensitivity of neutrons to this element and its major isotope, deuterium. Furthermore, neutrons exhibit wave properties that allow us to use them in similar ways to light, X-rays and electrons. This review aims to explain the basics of biological neutron science to encourage its greater use in solving difficult problems in the life sciences.

Crystal Structures of HLA-A*0201 Complexed with Melan-A/MART-1[subscript 26(27L)-35] Peptidomimetics Reveal Conformational Heterogeneity and Highlight Degeneracy of T Cell Recognition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Douat-Casassus, Celine; Borbulevych, Oleg; Tarbe, Marion

2010-10-07

There is growing interest in using tumor associated antigens presented by class I major histocompatibility complex (MHC-I) proteins as cancer vaccines. As native peptides are poorly stable in biological fluids, researchers have sought to engineer synthetic peptidomimetics with greater biostability. Here, we demonstrate that antigenic peptidomimetics of the Melan-A/MART-1{sub 26(27L)-35} melanoma antigen adopt strikingly different conformations when bound to MHC-I, highlighting the degeneracy of T cell recognition and revealing the challenges associated with mimicking native peptide conformation.

Neutrons for biologists: a beginner's guide, or why you should consider using neutrons

PubMed Central

Lakey, Jeremy H.

2009-01-01

From the structures of isolated protein complexes to the molecular dynamics of whole cells, neutron methods can achieve a resolution in complex systems that is inaccessible to other techniques. Biology is fortunate in that it is rich in water and hydrogen, and this allows us to exploit the differential sensitivity of neutrons to this element and its major isotope, deuterium. Furthermore, neutrons exhibit wave properties that allow us to use them in similar ways to light, X-rays and electrons. This review aims to explain the basics of biological neutron science to encourage its greater use in solving difficult problems in the life sciences. PMID:19656821

Variability in Rheumatology day care hospitals in Spain: VALORA study.

PubMed

Hernández Miguel, María Victoria; Martín Martínez, María Auxiliadora; Corominas, Héctor; Sanchez-Piedra, Carlos; Sanmartí, Raimon; Fernandez Martinez, Carmen; García-Vicuña, Rosario

To describe the variability of the day care hospital units (DCHUs) of Rheumatology in Spain, in terms of structural resources and operating processes. Multicenter descriptive study with data from a self-completed questionnaire of DCHUs self-assessment based on DCHUs quality standards of the Spanish Society of Rheumatology. Structural resources and operating processes were analyzed and stratified by hospital complexity (regional, general, major and complex). Variability was determined using the coefficient of variation (CV) of the variable with clinical relevance that presented statistically significant differences when was compared by centers. A total of 89 hospitals (16 autonomous regions and Melilla) were included in the analysis. 11.2% of hospitals are regional, 22,5% general, 27%, major and 39,3% complex. A total of 92% of DCHUs were polyvalent. The number of treatments applied, the coordination between DCHUs and hospital pharmacy and the post graduate training process were the variables that showed statistically significant differences depending on the complexity of hospital. The highest rate of rheumatologic treatments was found in complex hospitals (2.97 per 1,000 population), and the lowest in general hospitals (2.01 per 1,000 population). The CV was 0.88 in major hospitals; 0.86 in regional; 0.76 in general, and 0.72 in the complex. there was variability in the number of treatments delivered in DCHUs, being greater in major hospitals and then in regional centers. Nonetheless, the variability in terms of structure and function does not seem due to differences in center complexity. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Reumatología y Colegio Mexicano de Reumatología. All rights reserved.

Crystallization of bi-functional ligand protein complexes.

PubMed

Antoni, Claudia; Vera, Laura; Devel, Laurent; Catalani, Maria Pia; Czarny, Bertrand; Cassar-Lajeunesse, Evelyn; Nuti, Elisa; Rossello, Armando; Dive, Vincent; Stura, Enrico Adriano

2013-06-01

Homodimerization is important in signal transduction and can play a crucial role in many other biological systems. To obtaining structural information for the design of molecules able to control the signalization pathways, the proteins involved will have to be crystallized in complex with ligands that induce dimerization. Bi-functional drugs have been generated by linking two ligands together chemically and the relative crystallizability of complexes with mono-functional and bi-functional ligands has been evaluated. There are problems associated with crystallization with such ligands, but overall, the advantages appear to be greater than the drawbacks. The study involves two matrix metalloproteinases, MMP-12 and MMP-9. Using flexible and rigid linkers we show that it is possible to control the crystal packing and that by changing the ligand-enzyme stoichiometric ratio, one can toggle between having one bi-functional ligand binding to two enzymes and having the same ligand bound to each enzyme. The nature of linker and its point of attachment on the ligand can be varied to aid crystallization, and such variations can also provide valuable structural information about the interactions made by the linker with the protein. We report here the crystallization and structure determination of seven ligand-dimerized complexes. These results suggest that the use of bi-functional drugs can be extended beyond the realm of protein dimerization to include all drug design projects. Copyright © 2013 Elsevier Inc. All rights reserved.

Structural, Spectroscopic, and Electrochemical Properties of Nonheme Fe(II)-Hydroquinonate Complexes: Synthetic Models of Hydroquinone Dioxygenases

PubMed Central

Baum, Amanda E.; Park, Heaweon; Wang, Denan; Lindeman, Sergey V.; Fiedler, Adam T.

2012-01-01

Using the tris(3,5-diphenylpyrazol-1-yl)borate (Ph2Tp) supporting ligand, a series of mono- and dinuclear ferrous complexes containing hydroquinonate (HQate) ligands have been prepared and structurally characterized with X-ray crystallography. The monoiron(II) complexes serve as faithful mimics of the substrate-bound form of hydroquinone dioxygenases (HQDOs) – a family of nonheme Fe enzymes that catalyze the oxidative cleavage of 1,4-dihydroxybenzene units. Reflecting the variety of HQDO substrates, the synthetic complexes feature both mono- and bidentate HQate ligands. The bidentate HQates cleanly provide five-coordinate, high-spin Fe(II) complexes with the general formula [Fe(Ph2Tp)(HLX)] (1X), where HLX is a HQate(1-) ligand substituted at the 2-position with a benzimidazolyl (1A), acetyl (1B and 1C), or methoxy (1D) group. In contrast, the monodentate ligand 2,6-dimethylhydroquinone (H2LF) exhibited a greater tendency to bridge between two Fe(II) centers, resulting in formation of [Fe2(Ph2Tp)2(μ-LF)(MeCN)] [2F(MeCN)]. However, addition of one equivalent of “free” pyrazole (Ph2pz) ligand provided the mononuclear complex, [Fe(Ph2Tp)(HLF)(Ph2pz)] [1F(Ph2pz)], which is stabilized by an intramolecular hydrogen bond between the HLF and Ph2pz donors. Complex 1F(Ph2pz) represents the first crystallographically-characterized example of a monoiron complex bound to an untethered HQate ligand. The geometric and electronic structures of the Fe/HQate complexes were further probed with spectroscopic (UV-vis absorption, 1H NMR) and electrochemical methods. Cyclic voltammograms of complexes in the 1X series revealed an Fe-based oxidation between 0 and −300 mV (vs. Fc+/0), in addition to irreversible oxidation(s) of the HQate ligand at higher potentials. The one-electron oxidized species (1Xox) were examined with UV-vis absorption and electron paramagnetic resonance (EPR) spectroscopies. PMID:22930005

Exploring canopy structure and function as a potential mechanism of sustain carbon sequestration in aging forests

NASA Astrophysics Data System (ADS)

Fotis, A. T.; Curtis, P.; Ricart, R.

2013-12-01

The notion that old-growth forests reach carbon neutrality has recently been challenged, but the mechanisms responsible for continued productivity have remained elusive. Increases in canopy structural complexity, defined by high horizontal and vertical variability in leaf distribution (rugosity), has been proposed as a mechanism for sustained high rates of above ground net primary production (ANPPw) in forests up to ~170 years by enhancing light use efficiency (LUE) and nitrogen use efficiency (NUE). However, a detailed understanding of how rugosity affects resource distribution within and among trees leading to greater LUE and NUE is not known. We propose that leaves in high rugosity plots receive greater photosynthetic photon flux density (PPFD) than leaves in low rugosity plots, causing shifts from shade- to sun- adapted leaves into deeper portions of the canopy, which is thought to increase the photosynthetic capacity of individuals and lead to higher carbon assimilation in forests. The goal of this research was to: 1) quantify different canopy structural characteristics using a portable canopy LiDAR (PCL) and; 2) assess how these structural characteristics affect resource distribution and subsequent changes in leaf morphological, physiological and biochemical traits in three broadleaf species (e.g., Acer rubrum, Quercus rubra and Fagus grandifolia) and one conifer species (e.g., Pinus strobus) at different levels in the canopy in plots with similar leaf are index (LAI) but highly contrasting rugosity levels. We found that gap fraction had a strong positive correlation with rugosity. High rugosity plots had a bimodal distribution of LAI that was concentrated at the top and bottom of the canopy with an open midstory (between 10-50% of total canopy height) whereas low rugosity plots had a more even distribution of leaves. Leaf mass per area (LMA) of all broadleaved species had a strong positive correlation with cumulative gap fraction (P. strobus had a relatively weaker, but strong positive correlation). On average, Q. rubra and F. grandifolia had greater LMA in high rugosity plots while LMA was greater for A. rubrum and P. strobus in low rugosity plots. These findings suggest that species are responding differently to canopy structural complexity and that leaf arrangement in space plays an important role in determining leaf level traits. Furthermore, this research demonstrates that PCL can be used for quick identification of canopy traits (e.g., average LMA) relevant to photosynthetic capacity, and thus, carbon sequestration potential, and therefore may become an important tool in forest management.

Synthesis of Amino Acid Precursors with Organic Solids in Planetesimals with Liquid Water

NASA Technical Reports Server (NTRS)

Kebukawa, Y; Misawa, S.; Matsukuma, J.; Chan, Q. H. S.; Kobayashi, J.; Tachibana, S.; Zolensky, M. E.

2017-01-01

Amino acids are important ingredients of life that would have been delivered to Earth by extraterrestrial sources, e.g., comets and meteorites. Amino acids are found in aqueously altered carbonaceous chondrites in good part in the form of precursors that release amino acids after acid hydrolysis. Meanwhile, most of the organic carbon (greater than 70 weight %) in carbonaceous chondrites exists in the form of solvent insoluble organic matter (IOM) with complex macromolecular structures. Complex macromolecular organic matter can be produced by either photolysis of interstellar ices or aqueous chemistry in planetesimals. We focused on the synthesis of amino acids during aqueous alteration, and demonstrated one-pot synthesis of a complex suite of amino acids simultaneously with IOM via hydrothermal experiments simulating the aqueous processing

Providing structural modules with self-integrity monitoring

NASA Astrophysics Data System (ADS)

Walton, W. B.; Ibanez, P.; Yessaie, G.

1988-08-01

With the advent of complex space structures (i.e., U.S. Space Station), the need for methods for remotely detecting structural damage will become greater. Some of these structures will have hundreds of individual structural elements (i.e., strut members). Should some of them become damaged, it could be virtually impossible to detect it using visual or similar inspection techniques. The damage of only a few individual members may or may not be a serious problem. However, should a significant number of the members be damaged, a significant problem could be created. The implementation of an appropriate remote damage detection scheme would greatly reduce the likelihood of a serious problem related to structural damage ever occurring. This report presents the results of the research conducted on remote structural damage detection approaches and the related mathematical algorithms. The research was conducted for the Small Business Innovation and Research (SBIR) Phase 2 National Aeronautics and Space Administration (NASA) Contract NAS7-961.

Providing structural modules with self-integrity monitoring

NASA Technical Reports Server (NTRS)

Walton, W. B.; Ibanez, P.; Yessaie, G.

1988-01-01

With the advent of complex space structures (i.e., U.S. Space Station), the need for methods for remotely detecting structural damage will become greater. Some of these structures will have hundreds of individual structural elements (i.e., strut members). Should some of them become damaged, it could be virtually impossible to detect it using visual or similar inspection techniques. The damage of only a few individual members may or may not be a serious problem. However, should a significant number of the members be damaged, a significant problem could be created. The implementation of an appropriate remote damage detection scheme would greatly reduce the likelihood of a serious problem related to structural damage ever occurring. This report presents the results of the research conducted on remote structural damage detection approaches and the related mathematical algorithms. The research was conducted for the Small Business Innovation and Research (SBIR) Phase 2 National Aeronautics and Space Administration (NASA) Contract NAS7-961.

Close encounters: Moving along bumps, breaks, and bubbles on expanded trinucleotide tracts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polyzos, Aris A.; McMurray, Cynthia T.

2017-06-09

Expansion of simple triplet repeats (TNR) underlies greater than 30 severe degenerative diseases. There is a good understanding of the major pathways generating an expansion, and the associated polymerases that operate during gap filling synthesis at these “difficult to copy” sequences. However, the mechanism by which a TNR is repaired depends on the type of lesion, the structural features imposed by the lesion, the assembled replication/repair complex, and the polymerase that encounters it. The relationships among these parameters are exceptionally complex and how they direct pathway choice is poorly understood. In this review, we consider the properties of polymerases, andmore » how encounters with GC-rich or abnormal structures might influence polymerase choice and the success of replication and repair. Insights over the last three years have highlighted new mechanisms that provide interesting choices to consider in protecting genome stability.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanner, Robert D.; Cherepy, Nerine J.; Young, Jr., Victor G.

In this study, we describe the synthesis and crystal structures of four iridium compounds containing the 2-(4,6-difluorophenyl)pyridyl ligand. Cleavage of dichloro-bridged iridium(III) dimers with phosphorus ligands leads to (46dfppy)2Ir(L)(Cl) where L = PPh 3 or P(OPh) 3. Treatment of the chloro compounds with cyanide forms the cyano complexes (46dfppy) 2Ir(L)(CN). All complexes exhibit a trans effect in their molecular structures due to the phosphorus ligands, with the phosphite having a greater effect than the phosphine. With L = PPh 3, blue photoluminescence with CIE coordinates (x = 0.16, y = 0.24), quantum yield of 0.66 ± 0.15 and 4.5 ±more » 0.5 μs decay time is measured. For L = P(OPh) 3, blue photoluminescence with CIE coordinates (x = 0.16, y = 0.21), quantum yield of 0.65 ± 0.15 and 2.9 ± 0.3 μs decay time is measured.« less

Reactions of salts of hexakis(pyridine N-oxide)M(II) complexes (M = Co, Ni, Zn) and alkali halides used in infrared spectroscopy

NASA Astrophysics Data System (ADS)

Padmos, J.; van Veen, A.

A number of salts of hexakis(pyridine N-oxide)zinc(II) complexes decompose in alkali halide pellets. Initially ion exchange occurs, often followed by the formation of Zn(pyno) 3X 2 (pyno = pyridine N-oxide; X = Br, Cl). The analogous cobalt and nickel compounds are nearly always stable. A mull between alkali halide plates gives greater amounts of the same product Washing this product with toluene gives Zn(pyno) 2X 2. Examples of i.r. and far i.r. spectra are given. Energetical and structural effects are discussed. Far i.r. spectra of M(pyno) 3X 2(M = Co, Zn) confirm the structure [M(pyno) 6][MX 4] for these compounds. New compounds are [Zn(pyno) 2(NO 3) 2], [Zn(pyno- d5) 2[NO 3) 2], [Zn(pyno- d5) 6](NO 3) 2 and [Zn(pyno) 6]I 2.

[Modulation of Kv4 channels by KChIPs clamping].

PubMed

Cui, Yuan-Yuan; Wang, Ke-Wei

2009-01-01

The rapidly inactivating (A-type) potassium channels regulate membrane excitability that defines the fundamental mechanism of neuronal functions such as pain signaling. Cytosolic Kv channel-interacting proteins KChIPs co-assemble with Kv4 (Shal) alpha subunits to form a native complex. The specific binding of auxiliary KChIPs to the Kv4 N-terminus results in modulation of gating properties, surface expression and subunit assembly of Kv4 channels. Based on recent structural efforts, here we attempt to emphasize the interaction between KChIPs and Kv4 channel complex in which a single KChIP1 molecule laterally clamps two neighboring Kv4.3 N-termini in a 4:4 manner. Greater insights into molecular mechanism between KChIPs and Kv4 interaction may provide therapeutic potentials by structure-based design of chemical compounds aimed at disrupting the protein-protein interaction for treatment of membrane excitability-related disorders.

Exploring the Molecular Design of Protein Interaction Sites with Molecular Dynamics Simulations and Free Energy Calculations†

PubMed Central

Liang, Shide; Li, Liwei; Hsu, Wei-Lun; Pilcher, Meaghan N.; Uversky, Vladimir; Zhou, Yaoqi; Dunker, A. Keith; Meroueh, Samy O.

2009-01-01

The significant work that has been invested toward understanding protein–protein interaction has not translated into significant advances in structure-based predictions. In particular redesigning protein surfaces to bind to unrelated receptors remains a challenge, partly due to receptor flexibility, which is often neglected in these efforts. In this work, we computationally graft the binding epitope of various small proteins obtained from the RCSB database to bind to barnase, lysozyme, and trypsin using a previously derived and validated algorithm. In an effort to probe the protein complexes in a realistic environment, all native and designer complexes were subjected to a total of nearly 400 ns of explicit-solvent molecular dynamics (MD) simulation. The MD data led to an unexpected observation: some of the designer complexes were highly unstable and decomposed during the trajectories. In contrast, the native and a number of designer complexes remained consistently stable. The unstable conformers provided us with a unique opportunity to define the structural and energetic factors that lead to unproductive protein–protein complexes. To that end we used free energy calculations following the MM-PBSA approach to determine the role of nonpolar effects, electrostatics and entropy in binding. Remarkably, we found that a majority of unstable complexes exhibited more favorable electrostatics than native or stable designer complexes, suggesting that favorable electrostatic interactions are not prerequisite for complex formation between proteins. However, nonpolar effects remained consistently more favorable in native and stable designer complexes reinforcing the importance of hydrophobic effects in protein–protein binding. While entropy systematically opposed binding in all cases, there was no observed trend in the entropy difference between native and designer complexes. A series of alanine scanning mutations of hot-spot residues at the interface of native and designer complexes showed less than optimal contacts of hot-spot residues with their surroundings in the unstable conformers, resulting in more favorable entropy for these complexes. Finally, disorder predictions revealed that secondary structures at the interface of unstable complexes exhibited greater disorder than the stable complexes. PMID:19113835

Synthesis, structural characterization, fluorescence, antimicrobial, antioxidant and DNA cleavage studies of Cu(II) complexes of formyl chromone Schiff bases.

PubMed

Kavitha, P; Saritha, M; Laxma Reddy, K

2013-02-01

Cu(II) complexes have been synthesized from different Schiff bases, such as 3-((2-hydroxy phenylimino)methyl)-4H-chromen-4-one (HL(1)), 2-((4-oxo-4H-chromen-3-yl)methylneamino) benzoicacid (HL(2)), 3-((3-hydroxypyridin-2-ylimino)methyl)-4H-chromen-4-one (HL(3)) and 3-((2-mercaptophenylimino)methyl)-4H-chromen-4-one (HL(4)). The complexes were characterized by analytical, molar conductance, IR, electronic, magnetic, ESR, thermal, powder XRD and SEM studies. The analytical data reveal that metal to ligand molar ratio is 1:2 in all the complexes. Molar conductivity data indicates that all the Cu(II) complexes are neutral. On the basis of magnetic and electronic spectral data, distorted octahedral geometry is proposed for all the Cu(II) complexes. Thermal behaviour of the synthesized complexes illustrates the presence of lattice water molecules in the complexes. X-ray diffraction studies reveal that all the ligands and their Cu(II) complexes have triclinic system with different unit cell parameters. Antimicrobial, antioxidant and DNA cleavage activities indicate that metal complexes exhibited greater activity as compared with ligands. Copyright © 2012 Elsevier B.V. All rights reserved.

Advanced composites for windmills

NASA Astrophysics Data System (ADS)

Bourquardez, G.

A development status assessment is conducted for advanced composite construction techniques for windmill blade structures which, as in the case of composite helicopter rotors, promise greater reliability, longer service life, superior performance, and lower costs. Composites in wind turbine applications must bear aerodynamic, inertial and gravitational loads in complex interaction cycles. Attention is given to large Darrieus-type vertical axis windmills, to which composite construction methods may offer highly effective pitch-control mechanisms, especially in the 'umbrella' configuration.

Co-ordinated structural and functional covariance in the adolescent brain underlies face processing performance

PubMed Central

Joel Shaw, Daniel; Mareček, Radek; Grosbras, Marie-Helene; Leonard, Gabriel; Bruce Pike, G.

2016-01-01

Our ability to process complex social cues presented by faces improves during adolescence. Using multivariate analyses of neuroimaging data collected longitudinally from a sample of 38 adolescents (17 males) when they were 10, 11.5, 13 and 15 years old, we tested the possibility that there exists parallel variations in the structural and functional development of neural systems supporting face processing. By combining measures of task-related functional connectivity and brain morphology, we reveal that both the structural covariance and functional connectivity among ‘distal’ nodes of the face-processing network engaged by ambiguous faces increase during this age range. Furthermore, we show that the trajectory of increasing functional connectivity between the distal nodes occurs in tandem with the development of their structural covariance. This demonstrates a tight coupling between functional and structural maturation within the face-processing network. Finally, we demonstrate that increased functional connectivity is associated with age-related improvements of face-processing performance, particularly in females. We suggest that our findings reflect greater integration among distal elements of the neural systems supporting the processing of facial expressions. This, in turn, might facilitate an enhanced extraction of social information from faces during a time when greater importance is placed on social interactions. PMID:26772669

Formation and antimicrobial activity of complexes of beta-cyclodextrin and some antimycotic imidazole derivatives.

PubMed

Van Doorne, H; Bosch, E H; Lerk, C F

1988-04-22

Complex formation between beta-cyclodextrin and six antimycotic imidazole derivatives has been studied. The solubility of all drugs was increased in the presence of beta-cyclodextrin. The smallest increase (approx. 5-fold) was observed for miconazol, and the largest increase (approx. 160-fold) was observed for bifonazol. Apparent 1:1-complex constants were measured and found to decrease in the order: bifonazol greater than ketoconazol greater than tioconazol greater than miconazol greater than itraconazol greater than clotrimazol. The complexes appeared to possess a low, if any, antimicrobial activity. Measurement of inhibition zone sizes, with four test organisms was used to study the release of the antimycotic drugs from topical preparations. The antimycotic drugs were more readily released from topical preparations containing beta-cyclodextrin than from the same vehicles without beta-cyclodextrin. The rationale of beta-cyclodextrin addition to antimycotic topical preparations is discussed.

Carbon cycling at the tipping point: Does ecosystem structure predict resistance to disturbance?

NASA Astrophysics Data System (ADS)

Gough, C. M.; Bond-Lamberty, B. P.; Stuart-Haentjens, E.; Atkins, J.; Haber, L.; Fahey, R. T.

2017-12-01

Ecosystems worldwide are subjected to disturbances that reshape their physical and biological structure and modify biogeochemical processes, including carbon storage and cycling rates. Disturbances, including those from insect pests, pathogens, and extreme weather, span a continuum of severity and, accordingly, may have different effects on carbon cycling processes. Some ecosystems resist biogeochemical changes following disturbance, until a critical threshold of severity is exceeded. The ecosystem properties underlying such functional resistance, and signifying when a tipping point will occur, however, are almost entirely unknown. Here, we present observational and experimental results from forests in the Great Lakes region, showing ecosystem structure is closely coupled with carbon cycling responses to disturbance, with shifts in structure predicting thresholds of and, in some cases, increases in carbon storage. We find, among forests in the region, that carbon storage regularly exhibits a non-linear threshold response to increasing disturbance levels, but the severity at which a threshold is reached varies among disturbed forests. More biologically and structurally complex forest ecosystems sometimes exhibit greater functional resistance than simpler forests, and consequently may have a higher disturbance severity threshold. Counter to model predictions but consistent with some theoretical frameworks, empirical data show moderate levels of disturbance may increase ecosystem complexity to a point, thereby increasing rates of carbon storage. Disturbances that increase complexity therefore may stimulate carbon storage, while severe disturbances at or beyond thresholds may simplify structure, leading to carbon storage declines. We conclude that ecosystem structural attributes are closely coupled with biogeochemical thresholds across disturbance severity gradients, suggesting that improved predictions of disturbance-related changes in the carbon cycle require better representation of ecosystem structure in models.

Thermal-structural modeling of polymer Bragg grating waveguides illuminated by a light emitting diode.

PubMed

Joon Kim, Kyoung; Bar-Cohen, Avram; Han, Bongtae

2012-02-20

This study reports both analytical and numerical thermal-structural models of polymer Bragg grating (PBG) waveguides illuminated by a light emitting diode (LED). A polymethyl methacrylate (PMMA) Bragg grating (BG) waveguide is chosen as an analysis vehicle to explore parametric effects of incident optical powers and substrate materials on the thermal-structural behavior of the BG. Analytical models are verified by comparing analytically predicted average excess temperatures, and thermally induced axial strains and stresses with numerical predictions. A parametric study demonstrates that the PMMA substrate induces more adverse effects, such as higher excess temperatures, complex axial temperature profiles, and greater and more complicated thermally induced strains in the BG compared with the Si substrate. © 2012 Optical Society of America

Structure-Function Analysis of Nonarteritic Anterior Ischemic Optic Neuropathy and Age-Related Differences in Outcome.

PubMed

Sun, Ming-Hui; Liao, Yaping Joyce

2017-09-01

The optic nerve head is vulnerable to ischemia leading to anterior ischemic optic neuropathy (AION), the most common acute optic neuropathy in those older than 50 years of age. We performed a cross-sectional study of 55 nonarteritic anterior ischemic optic neuropathy (NAION) eyes in 34 patients to assess clinical outcome and perform structure-function correlations. The peak age of NAION onset was between 50 and 55 years. Sixty-seven percent of patients presented with their first event between the ages of 40 and 60 years, and 32% presented at ≤50 years. Those with NAION onset at age ≤50 years did not have significantly better visual outcome per logMAR visual acuity, automated perimetric mean deviation (PMD) or optical coherence tomography (OCT) measurements. Kaplan-Meier survival curve and multivariate Cox proportional regression analysis showed that age >50 years at NAION onset was associated with greater risk of second eye involvement, with hazard ratio of 20. Older age at onset was significantly correlated with greater thinning of the ganglion cell complex (GCC) (P = 0.022) but not with logMAR visual acuity, PMD, or thinning of retinal nerve fiber layer (RNFL). Using area under receiver operating characteristic curve analyses, we found that thinning of RNFL and GCC was best able to predict visual outcome, and that mean RNFL thickness >65 μm or macular GCC thickness >55 μm significantly correlated with good visual field outcome. We showed that NAION onset at age >50 years had a greater risk of second eye involvement. Patients with OCT mean RNFL thickness >65 μm and mean macular ganglion cell complex thickness >55 μm had better visual outcomes.

RNA and RNP as Building Blocks for Nanotechnology and Synthetic Biology.

PubMed

Ohno, Hirohisa; Saito, Hirohide

2016-01-01

Recent technologies that aimed to elucidate cellular function have revealed essential roles for RNA molecules in living systems. Our knowledge concerning functional and structural information of naturally occurring RNA and RNA-protein (RNP) complexes is increasing rapidly. RNA and RNP interaction motifs are structural units that function as building blocks to constitute variety of complex structures. RNA-central synthetic biology and nanotechnology are constructive approaches that employ the accumulated information and build synthetic RNA (RNP)-based circuits and nanostructures. Here, we describe how to design and construct synthetic RNA (RNP)-based devices and structures at the nanometer-scale for biological and future therapeutic applications. RNA/RNP nanostructures can also be utilized as the molecular scaffold to control the localization or interactions of target molecule(s). Moreover, RNA motifs recognized by RNA-binding proteins can be applied to make protein-responsive translational "switches" that can turn gene expression "on" or "off" depending on the intracellular environment. This "synthetic RNA and RNP world" will expand tools for nanotechnology and synthetic biology. In addition, these reconstructive approaches would lead to a greater understanding of building principle in naturally occurring RNA/RNP molecules and systems. Copyright © 2016 Elsevier Inc. All rights reserved.

Peptide and Peptide-Dependent Motions in MHC Proteins: Immunological Implications and Biophysical Underpinnings

PubMed Central

Ayres, Cory M.; Corcelli, Steven A.; Baker, Brian M.

2017-01-01

Structural biology of peptides presented by class I and class II MHC proteins has transformed immunology, impacting our understanding of fundamental immune mechanisms and allowing researchers to rationalize immunogenicity and design novel vaccines. However, proteins are not static structures as often inferred from crystallographic structures. Their components move and breathe individually and collectively over a range of timescales. Peptides bound within MHC peptide-binding grooves are no exception and their motions have been shown to impact recognition by T cell and other receptors in ways that influence function. Furthermore, peptides tune the motions of MHC proteins themselves, which impacts recognition of peptide/MHC complexes by other proteins. Here, we review the motional properties of peptides in MHC binding grooves and discuss how peptide properties can influence MHC motions. We briefly review theoretical concepts about protein motion and highlight key data that illustrate immunological consequences. We focus primarily on class I systems due to greater availability of data, but segue into class II systems as the concepts and consequences overlap. We suggest that characterization of the dynamic “energy landscapes” of peptide/MHC complexes and the resulting functional consequences is one of the next frontiers in structural immunology. PMID:28824655

Peptide and Peptide-Dependent Motions in MHC Proteins: Immunological Implications and Biophysical Underpinnings.

PubMed

Ayres, Cory M; Corcelli, Steven A; Baker, Brian M

2017-01-01

Structural biology of peptides presented by class I and class II MHC proteins has transformed immunology, impacting our understanding of fundamental immune mechanisms and allowing researchers to rationalize immunogenicity and design novel vaccines. However, proteins are not static structures as often inferred from crystallographic structures. Their components move and breathe individually and collectively over a range of timescales. Peptides bound within MHC peptide-binding grooves are no exception and their motions have been shown to impact recognition by T cell and other receptors in ways that influence function. Furthermore, peptides tune the motions of MHC proteins themselves, which impacts recognition of peptide/MHC complexes by other proteins. Here, we review the motional properties of peptides in MHC binding grooves and discuss how peptide properties can influence MHC motions. We briefly review theoretical concepts about protein motion and highlight key data that illustrate immunological consequences. We focus primarily on class I systems due to greater availability of data, but segue into class II systems as the concepts and consequences overlap. We suggest that characterization of the dynamic "energy landscapes" of peptide/MHC complexes and the resulting functional consequences is one of the next frontiers in structural immunology.

Chroman-4-One Derivatives Targeting Pteridine Reductase 1 and Showing Anti-Parasitic Activity.

PubMed

Di Pisa, Flavio; Landi, Giacomo; Dello Iacono, Lucia; Pozzi, Cecilia; Borsari, Chiara; Ferrari, Stefania; Santucci, Matteo; Santarem, Nuno; Cordeiro-da-Silva, Anabela; Moraes, Carolina B; Alcantara, Laura M; Fontana, Vanessa; Freitas-Junior, Lucio H; Gul, Sheraz; Kuzikov, Maria; Behrens, Birte; Pöhner, Ina; Wade, Rebecca C; Costi, Maria Paola; Mangani, Stefano

2017-03-08

Flavonoids have previously been identified as antiparasitic agents and pteridine reductase 1 (PTR1) inhibitors. Herein, we focus our attention on the chroman-4-one scaffold. Three chroman-4-one analogues ( 1 - 3 ) of previously published chromen-4-one derivatives were synthesized and biologically evaluated against parasitic enzymes ( Trypanosoma brucei PTR1- Tb PTR1 and Leishmania major-Lm PTR1) and parasites ( Trypanosoma brucei and Leishmania infantum ). A crystal structure of Tb PTR1 in complex with compound 1 and the first crystal structures of Lm PTR1-flavanone complexes (compounds 1 and 3 ) were solved. The inhibitory activity of the chroman-4-one and chromen-4-one derivatives was explained by comparison of observed and predicted binding modes of the compounds. Compound 1 showed activity both against the targeted enzymes and the parasites with a selectivity index greater than 7 and a low toxicity. Our results provide a basis for further scaffold optimization and structure-based drug design aimed at the identification of potent anti-trypanosomatidic compounds targeting multiple PTR1 variants.

The facile synthesis of a chitosan Cu(II) complex by solution plasma process and evaluation of their antioxidant activities.

PubMed

Ma, Fengming; Li, Pu; Zhang, Baiqing; Wang, Zhenyu

2017-10-01

Synthesis of chitosan-Cu(II) complex by solution plasma process (SPP) irradiation was investigated. The effects of the distance between the electrodes, initial Cu(II) concentration, and initial pH on the Cu(II) adsorption capacity were evaluated. The results showed that narrower distance between the electrodes, higher initial Cu(II) concentration and higher initial pH (at pH<6) were favourable for the adsorption capacity of Cu(II). Characterization of the chitosan-Cu(II) complex by ultraviolet-visible (UV-vis), fourier transform infrared (FT-IR) and electron spin resonance (ESR) spectroscopy revealed that the main structure of chitosan was not changed after irradiation. Thermogravimetry (TG) analysis indicated that Cu(II) ions were well incorporated into the chitosan. The antioxidant activity of the chitosan-Cu(II) complex was evaluated by DPPH, ABTS, and reducing power assays. The chitosan-Cu(II) complex exhibited greater antioxidant activity than the original chitosan. Thus, SPP could be used for preparation of chitosan-Cu(II) complexes. Copyright © 2017. Published by Elsevier B.V.

Kinetic analyses of vasculogenesis inform mechanistic studies

PubMed Central

Winfree, Seth; Chu, Chenghao; Tu, Wanzhu; Blue, Emily K.; Gohn, Cassandra R.; Dunn, Kenneth W.

2017-01-01

Vasculogenesis is a complex process by which endothelial stem and progenitor cells undergo de novo vessel formation. Quantitative assessment of vasculogenesis is a central readout of endothelial progenitor cell functionality. However, current assays lack kinetic measurements. To address this issue, new approaches were developed to quantitatively assess in vitro endothelial colony-forming cell (ECFC) network formation in real time. Eight parameters of network structure were quantified using novel Kinetic Analysis of Vasculogenesis (KAV) software. KAV assessment of structure complexity identified two phases of network formation. This observation guided the development of additional vasculogenic readouts. A tissue cytometry approach was established to quantify the frequency and localization of dividing ECFCs. Additionally, Fiji TrackMate was used to quantify ECFC displacement and speed at the single-cell level during network formation. These novel approaches were then implemented to identify how intrauterine exposure to maternal diabetes mellitus (DM) impairs fetal ECFC vasculogenesis. Fetal ECFCs exposed to maternal DM form fewer initial network structures, which are not stable over time. Correlation analyses demonstrated that ECFC samples with greater division in branches form fewer closed network structures. Additionally, reductions in average ECFC movement over time decrease structural connectivity. Identification of these novel phenotypes utilizing the newly established methodologies provides evidence for the cellular mechanisms contributing to aberrant ECFC vasculogenesis. PMID:28100488

Structural Basis for High Affinity Volatile Anesthetic Binding in a Natural 4-helix Bundle Protein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu,R.; Loll, P.; Eckenhoff, R.

2005-01-01

Physiologic sites for inhaled anesthetics are presumed to be cavities within transmembrane 4-{alpha}-helix bundles of neurotransmitter receptors, but confirmation of binding and structural detail of such sites remains elusive. To provide such detail, we screened soluble proteins containing this structural motif, and found only one that exhibited evidence of strong anesthetic binding. Ferritin is a 24-mer of 4-{alpha}-helix bundles; both halothane and isoflurane bind with K{sub A} values of {approx}10{sup 5} M{sup -1, } higher than any previously reported inhaled anesthetic-protein interaction. The crystal structures of the halothane/apoferritin and isoflurane/apoferritin complexes were determined at 1.75 Angstroms resolution, revealing a commonmore » anesthetic binding pocket within an interhelical dimerization interface. The high affinity is explained by several weak polar contacts and an optimal host/guest packing relationship. Neither the acidic protons nor ether oxygen of the anesthetics contribute to the binding interaction. Compared with unliganded apoferritin, the anesthetic produced no detectable alteration of structure or B factors. The remarkably high affinity of the anesthetic/apoferritin complex implies greater selectivity of protein sites than previously thought, and suggests that direct protein actions may underlie effects at lower than surgical levels of anesthetic, including loss of awareness.« less

Stability and structural properties of gene regulation networks with coregulation rules.

PubMed

Warrell, Jonathan; Mhlanga, Musa

2017-05-07

Coregulation of the expression of groups of genes has been extensively demonstrated empirically in bacterial and eukaryotic systems. Such coregulation can arise through the use of shared regulatory motifs, which allow the coordinated expression of modules (and module groups) of functionally related genes across the genome. Coregulation can also arise through the physical association of multi-gene complexes through chromosomal looping, which are then transcribed together. We present a general formalism for modeling coregulation rules in the framework of Random Boolean Networks (RBN), and develop specific models for transcription factor networks with modular structure (including module groups, and multi-input modules (MIM) with autoregulation) and multi-gene complexes (including hierarchical differentiation between multi-gene complex members). We develop a mean-field approach to analyse the dynamical stability of large networks incorporating coregulation, and show that autoregulated MIM and hierarchical gene-complex models can achieve greater stability than networks without coregulation whose rules have matching activation frequency. We provide further analysis of the stability of small networks of both kinds through simulations. We also characterize several general properties of the transients and attractors in the hierarchical coregulation model, and show using simulations that the steady-state distribution factorizes hierarchically as a Bayesian network in a Markov Jump Process analogue of the RBN model. Copyright © 2017. Published by Elsevier Ltd.

A review of current evidence regarding the ICD-11 proposals for diagnosing PTSD and complex PTSD.

PubMed

Brewin, Chris R; Cloitre, Marylène; Hyland, Philip; Shevlin, Mark; Maercker, Andreas; Bryant, Richard A; Humayun, Asma; Jones, Lynne M; Kagee, Ashraf; Rousseau, Cécile; Somasundaram, Daya; Suzuki, Yuriko; Wessely, Simon; van Ommeren, Mark; Reed, Geoffrey M

2017-12-01

The World Health Organization's proposals for posttraumatic stress disorder (PTSD) in the 11th edition of the International Classification of Diseases, scheduled for release in 2018, involve a very brief set of symptoms and a distinction between two sibling disorders, PTSD and Complex PTSD. This review of studies conducted to test the validity and implications of the diagnostic proposals generally supports the proposed 3-factor structure of PTSD symptoms, the 6-factor structure of Complex PTSD symptoms, and the distinction between PTSD and Complex PTSD. Estimates derived from DSM-based items suggest the likely prevalence of ICD-11 PTSD in adults is lower than ICD-10 PTSD and lower than DSM-IV or DSM-5 PTSD, but this may change with the development of items that directly measure the ICD-11 re-experiencing requirement. Preliminary evidence suggests the prevalence of ICD-11 PTSD in community samples of children and adolescents is similar to DSM-IV and DSM-5. ICD-11 PTSD detects some individuals with significant impairment who would not receive a diagnosis under DSM-IV or DSM-5. ICD-11 CPTSD identifies a distinct group who have more often experienced multiple and sustained traumas and have greater functional impairment than those with PTSD. Copyright © 2017 Elsevier Ltd. All rights reserved.

Taxonomic and compositional differences of ground-dwelling arthropods in riparian habitats in Glen Canyon, Arizona, USA

USGS Publications Warehouse

Ralston, Barbara; Cobb, Neil S.; Brantley, Sandra L.; Higgins, Jacob; Yackulic, Charles B.

2017-01-01

The disturbance history, plant species composition, productivity, and structural complexity of a site can exert bottom-up controls on arthropod diversity, abundance, and trophic structure. Regulation alters the hydrology and disturbance regimes of rivers and affects riparian habitats by changing plant quality parameters. Fifty years of regulation along the Colorado River downstream of Glen Canyon Dam has created a no-analog, postdam “lower” riparian zone close to the water's edge that includes tamarisk (Tamarix sp.), a nonnative riparian shrub. At the same time, the predam “upper” facultative riparian zone has persisted several meters above the current flood stage. In summer 2009, we used pitfall traps within these 2 riparian zones that differ in plant composition, productivity, and disturbance frequency to test for differences in arthropod community (Hymenoptera, Arachnida, and Coleoptera) structure. Arthropod community structure differed substantially between the 2 zones. Arthropod abundance and species richness was highest in the predam upper riparian zone, even though there was a greater amount of standing plant biomass in the postdam lower riparian zone. Omnivore abundance was proportionately greater in the upper riparian zone and was associated with lower estimated productivity values. Predators and detritivores were proportionately greater in the postdam lower riparian zone. In this case, river regulation may create habitats that support species of spiders and carabid beetles, but few other species that are exclusive to this zone. The combined richness found in both zones suggests a small increase in total richness and functional diversity for the Glen Canyon reach of the Colorado River.

Structure Detection of Nonlinear Aeroelastic Systems with Application to Aeroelastic Flight Test Data. Part 2

NASA Technical Reports Server (NTRS)

Kukreja, Sunil L.; Brenner, martin J.

2006-01-01

This viewgraph presentation reviews the 1. Motivation for the study 2. Nonlinear Model Form 3. Structure Detection 4. Least Absolute Shrinkage and Selection Operator (LASSO) 5. Objectives 6. Results 7. Assess LASSO as a Structure Detection Tool: Simulated Nonlinear Models 8. Applicability to Complex Systems: F/A-18 Active Aeroelastic Wing Flight Test Data. The authors conclude that 1. this is a novel approach for detecting the structure of highly over-parameterised nonlinear models in situations where other methods may be inadequate 2. that it is a practical significance in the analysis of aircraft dynamics during envelope expansion and could lead to more efficient control strategies and 3. this could allow greater insight into the functionality of various systems dynamics, by providing a quantitative model which is easily interpretable

The effects of lithium and anticonvulsants on brain structure in bipolar disorder.

PubMed

Germaná, C; Kempton, M J; Sarnicola, A; Christodoulou, T; Haldane, M; Hadjulis, M; Girardi, P; Tatarelli, R; Frangou, S

2010-12-01

To investigate the effect of lithium, anticonvulsants and antipsychotics on brain structure in bipolar disorder (BD). A cross-sectional structural brain magnetic resonance imaging study of 74 remitted patients with BD, aged 18-65, who were receiving long-term prophylactic treatment with lithium or anticonvulsants or antipsychotics. Global and regional grey matter, white matter, and cerebrospinal fluid volumes were compared between treatment groups. Grey matter in the subgenual anterior cingulate gyrus on the right (extending into the hypothalamus) and in the postcentral gyrus, the hippocampus/amygdale complex and the insula on the left was greater in BD patients on lithium treatment compared to all other treatment groups. Lithium treatment in BD has a significant effect on brain structure particularly in limbic/paralimbic regions associated with emotional processing. © 2010 John Wiley & Sons A/S.

Complex analysis of movement in evaluation of flat bench press performance.

PubMed

Król, Henryk; Golas, Artur; Sobota, Grzegorz

2010-01-01

The complex methodology of investigations was applied to study a movement structure on bench press. We have checked the usefulness of multimodular measuring system (SMART-E, BTS company, Italy) and a special device for tracking the position of barbell (pantograph). Software Smart Analyser was used to create a database allowing chosen parameters to be compared. The results from different measuring devices are very similar, therefore the replacement of many devices by one multimodular system is reasonable. In our study, the effect of increased barbell load on the values of muscles activity and bar kinematics during the flat bench press movement was clearly visible. The greater the weight of a barbell, the greater the myoactivity of shoulder muscles and vertical velocity of the bar. It was also confirmed the presence of the so-called sticking point (period) during the concentric phase of the bench press. In this study, the initial velocity of the barbell decreased (v(min)) not only under submaximal and maximal loads (90 and 100% of the one repetition maximum; 1-RM), but also under slightly lighter weights (70 and 80% of 1-RM).

The Role of Care Coordinator for Children with Complex Care Needs: A Systematic Review

PubMed Central

Hillis, Rowan; Larkin, Philip J; Cawley, Des; Connolly, Michael

2016-01-01

Introduction: This systematic review seeks to identify the intended components of the role of care coordinator for children with complex care needs and the factors that determine its composition in practice. Theory and methods: The initial search identified 1,157 articles, of which 37 met the inclusion criteria. They were quality assessed using the SIGN hierarchy of evidence structure. Results: Core components of the role include: coordination of care needs, planning and assessment, specialist support, emotional support, administration and logistics and continuing professional development. Influencing factors on the role include the external environment (political and socio-economic), the internal environment (organisational structure and funding protocols), the skills, qualifications and experience of the coordinator, the family circumstances and the nature of the interaction between the care coordinator and the family. Discussion: The lack of consistent terminology creates challenges and there is a need for greater consensus on this issue. Organisations and healthcare professionals need to recognise the extent to which contextual factors influence the role of a care coordinator in practice and plan accordingly. Despite evidence that suggests that the role is pivotal in ensuring that care needs are sustained, there remains great variability in the understanding of the role of a care coordinator for this population. Conclusions: As the provision of care increasingly moves closer to home there is a need for greater understanding of the nature and composition of the interaction between care coordinators and families to determine the extent to which appropriate services are being provided. Further work in this area should take into consideration any potential variance in service provision, for example any potential inequity arising due to geographic location. It is also imperative, where appropriate, to seek the views of children with complex care needs and their siblings about their experiences. PMID:27616967

Predicting landslide vegetation in patches on landscape gradients in Puerto Rico

USGS Publications Warehouse

Myster, R.W.; Thomlinson, J.R.; Larsen, M.C.

1997-01-01

We explored the predictive value of common landscape characteristics for landslide vegetative stages in the Luquillo Experimental Forest of Puerto Rico using four different analyses. Maximum likelihood logistic regression showed that aspect, age, and substrate type could be used to predict vegetative structural stage. In addition it showed that the structural complexity of the vegetation was greater in landslides (1) facing the southeast (away from the dominant wind direction of recent hurricanes), (2) that were older, and (3) that had volcaniclastic rather than dioritic substrate. Multiple regression indicated that both elevation and age could be used to predict the current vegetation, and that vegetation complexity was greater both at lower elevation and in older landslides. Pearson product-moment correlation coefficients showed that (1) the presence of volcaniclastic substrate in landslides was negatively correlated with aspect, age, and elevation, (2) that road association and age were positively correlated, and (3) that slope was negatively correlated with area. Finally, principal components analysis showed that landslides were differentiated on axes defined primarily by age, aspect class, and elevation in the positive direction, and by volcaniclastic substrate in the negative direction. Because several statistical techniques indicated that age, aspect, elevation, and substrate were important in determining vegetation complexity on landslides, we conclude that landslide succession is influenced by variation in these landscape traits. In particular, we would expect to find more successional development on landslides which are older, face away from hurricane winds, are at lower elevation, and are on volcaniclastic substrate. Finally, our results lead into a hierarchical conceptual model of succession on landscapes where the biota respond first to either gradients or disturbance depending on their relative severity, and then to more local biotic mechanisms such as dispersal, predation and competition.

Sparse RNA folding revisited: space-efficient minimum free energy structure prediction.

PubMed

Will, Sebastian; Jabbari, Hosna

2016-01-01

RNA secondary structure prediction by energy minimization is the central computational tool for the analysis of structural non-coding RNAs and their interactions. Sparsification has been successfully applied to improve the time efficiency of various structure prediction algorithms while guaranteeing the same result; however, for many such folding problems, space efficiency is of even greater concern, particularly for long RNA sequences. So far, space-efficient sparsified RNA folding with fold reconstruction was solved only for simple base-pair-based pseudo-energy models. Here, we revisit the problem of space-efficient free energy minimization. Whereas the space-efficient minimization of the free energy has been sketched before, the reconstruction of the optimum structure has not even been discussed. We show that this reconstruction is not possible in trivial extension of the method for simple energy models. Then, we present the time- and space-efficient sparsified free energy minimization algorithm SparseMFEFold that guarantees MFE structure prediction. In particular, this novel algorithm provides efficient fold reconstruction based on dynamically garbage-collected trace arrows. The complexity of our algorithm depends on two parameters, the number of candidates Z and the number of trace arrows T; both are bounded by [Formula: see text], but are typically much smaller. The time complexity of RNA folding is reduced from [Formula: see text] to [Formula: see text]; the space complexity, from [Formula: see text] to [Formula: see text]. Our empirical results show more than 80 % space savings over RNAfold [Vienna RNA package] on the long RNAs from the RNA STRAND database (≥2500 bases). The presented technique is intentionally generalizable to complex prediction algorithms; due to their high space demands, algorithms like pseudoknot prediction and RNA-RNA-interaction prediction are expected to profit even stronger than "standard" MFE folding. SparseMFEFold is free software, available at http://www.bioinf.uni-leipzig.de/~will/Software/SparseMFEFold.

Conserving intertidal habitats: What is the potential of ecological engineering to mitigate impacts of coastal structures?

NASA Astrophysics Data System (ADS)

Perkins, Matthew J.; Ng, Terence P. T.; Dudgeon, David; Bonebrake, Timothy C.; Leung, Kenneth M. Y.

2015-12-01

Globally, coastlines are under pressure as coastal human population growth and urbanization continues, while climatic change leads to stormier seas and rising tides. These trends create a strong and sustained demand for land reclamation and infrastructure protection in coastal areas, requiring engineered coastal defence structures such as sea walls. Here, we review the nature of ecological impacts of coastal structures on intertidal ecosystems, seek to understand the extent to which ecological engineering can mitigate these impacts, and evaluate the effectiveness of mitigation as a tool to contribute to conservation of intertidal habitats. By so doing, we identify critical knowledge gaps to inform future research. Coastal structures alter important physical, chemical and biological processes of intertidal habitats, and strongly impact community structure, inter-habitat linkages and ecosystem services while also driving habitat loss. Such impacts occur diffusely across localised sites but scale to significant regional and global levels. Recent advances in ecological engineering have focused on developing habitat complexity on coastal structures to increase biodiversity. 'Soft' engineering options maximise habitat complexity through inclusion of natural materials, species and processes, while simultaneously delivering engineering objectives such as coastal protection. Soft options additionally sustain multiple services, providing greater economic benefits for society, and resilience to climatic change. Currently however, a lack of inclusion and economic undervaluation of intertidal ecosystem services may undermine best practice in coastline management. Importantly, reviewed evidence shows mitigation and even restoration do not support intertidal communities or processes equivalent to pre-disturbance conditions. Crucially, an absence of comprehensive empirical baseline biodiversity data, or data comprising additional ecological parameters such as ecosystem functions and services, prohibits quantification of absolute and relative magnitudes of ecological impacts due to coastal structures or effectiveness of mitigation interventions. This knowledge deficit restricts evaluation of the potential of ecological engineering to contribute to conservation policies for intertidal habitats. To improve mitigation design and effectiveness, a greater focus on in-situ research is needed, requiring stronger and timely collaboration between government agencies, construction partners and research scientists.

Co-ordinated structural and functional covariance in the adolescent brain underlies face processing performance.

PubMed

Shaw, Daniel Joel; Mareček, Radek; Grosbras, Marie-Helene; Leonard, Gabriel; Pike, G Bruce; Paus, Tomáš

2016-04-01

Our ability to process complex social cues presented by faces improves during adolescence. Using multivariate analyses of neuroimaging data collected longitudinally from a sample of 38 adolescents (17 males) when they were 10, 11.5, 13 and 15 years old, we tested the possibility that there exists parallel variations in the structural and functional development of neural systems supporting face processing. By combining measures of task-related functional connectivity and brain morphology, we reveal that both the structural covariance and functional connectivity among 'distal' nodes of the face-processing network engaged by ambiguous faces increase during this age range. Furthermore, we show that the trajectory of increasing functional connectivity between the distal nodes occurs in tandem with the development of their structural covariance. This demonstrates a tight coupling between functional and structural maturation within the face-processing network. Finally, we demonstrate that increased functional connectivity is associated with age-related improvements of face-processing performance, particularly in females. We suggest that our findings reflect greater integration among distal elements of the neural systems supporting the processing of facial expressions. This, in turn, might facilitate an enhanced extraction of social information from faces during a time when greater importance is placed on social interactions. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Predation Risk Shapes Social Networks in Fission-Fusion Populations

PubMed Central

Kelley, Jennifer L.; Morrell, Lesley J.; Inskip, Chloe; Krause, Jens; Croft, Darren P.

2011-01-01

Predation risk is often associated with group formation in prey, but recent advances in methods for analysing the social structure of animal societies make it possible to quantify the effects of risk on the complex dynamics of spatial and temporal organisation. In this paper we use social network analysis to investigate the impact of variation in predation risk on the social structure of guppy shoals and the frequency and duration of shoal splitting (fission) and merging (fusion) events. Our analyses revealed that variation in the level of predation risk was associated with divergent social dynamics, with fish in high-risk populations displaying a greater number of associations with overall greater strength and connectedness than those from low-risk sites. Temporal patterns of organisation also differed according to predation risk, with fission events more likely to occur over two short time periods (5 minutes and 20 minutes) in low-predation fish and over longer time scales (>1.5 hours) in high-predation fish. Our findings suggest that predation risk influences the fine-scale social structure of prey populations and that the temporal aspects of organisation play a key role in defining social systems. PMID:21912627

Lithospheric architecture of NE China from joint Inversions of receiver functions and surface wave dispersion through Bayesian optimisation

NASA Astrophysics Data System (ADS)

Sebastian, Nita; Kim, Seongryong; Tkalčić, Hrvoje; Sippl, Christian

2017-04-01

The purpose of this study is to develop an integrated inference on the lithospheric structure of NE China using three passive seismic networks comprised of 92 stations. The NE China plain consists of complex lithospheric domains characterised by the co-existence of complex geodynamic processes such as crustal thinning, active intraplate cenozoic volcanism and low velocity anomalies. To estimate lithospheric structures with greater detail, we chose to perform the joint inversion of independent data sets such as receiver functions and surface wave dispersion curves (group and phase velocity). We perform a joint inversion based on principles of Bayesian transdimensional optimisation techniques (Kim etal., 2016). Unlike in the previous studies of NE China, the complexity of the model is determined from the data in the first stage of the inversion, and the data uncertainty is computed based on Bayesian statistics in the second stage of the inversion. The computed crustal properties are retrieved from an ensemble of probable models. We obtain major structural inferences with well constrained absolute velocity estimates, which are vital for inferring properties of the lithosphere and bulk crustal Vp/Vs ratio. The Vp/Vs estimate obtained from joint inversions confirms the high Vp/Vs ratio ( 1.98) obtained using the H-Kappa method beneath some stations. Moreover, we could confirm the existence of a lower crustal velocity beneath several stations (eg: station SHS) within the NE China plain. Based on these findings we attempt to identify a plausible origin for structural complexity. We compile a high-resolution 3D image of the lithospheric architecture of the NE China plain.

Electron Spin Resonance Studies of Carbonic Anhydrase: Transition Metal Ions and Spin-Labeled Sulfonamides*

PubMed Central

Taylor, June S.; Mushak, Paul; Coleman, Joseph E.

1970-01-01

Electron spin resonance (esr) spectra of Cu(II) and Co(II) carbonic anhydrase, and a spin-labeled sulfonamide complex of the Zn(II) enzyme, are reported. The coordination geometry of Cu(II) bound in the enzyme appears to have approximately axial symmetry. Esr spectra of enzyme complexes with metal-binding anions also show axial symmetry and greater covalency, in the order ethoxzolamide < SH- < N3- ≤ CN-. Well-resolved superhyperfine structure in the spectrum of the cyanide complex suggests the presence of two, and probably three, equivalent nitrogen ligands from the protein. Esr spectra of the Co(II) enzyme and its complexes show two types of Co(II) environment, one typical of the native enzyme and the 1:1 CN- complex, and one typical of a 2:1 CN- complex. Co(II) in the 2:1 complex appears to be low-spin and probably has a coordination number of 5. Binding of a spin-labeled sulfonamide to the active center immobilizes the free radical. The similarity of the esr spectra of spin-labeled Zn(II) and Co(II) carbonic anhydrases suggests that the conformation at the active center is similar in the two metal derivatives. PMID:4320976

Folate-conjugated boron nitride nanospheres for targeted delivery of anticancer drugs.

PubMed

Feng, Shini; Zhang, Huijie; Yan, Ting; Huang, Dandi; Zhi, Chunyi; Nakanishi, Hideki; Gao, Xiao-Dong

With its unique physical and chemical properties and structural similarity to carbon, boron nitride (BN) has attracted considerable attention and found many applications. Biomedical applications of BN have recently started to emerge, raising great hopes in drug and gene delivery. Here, we developed a targeted anticancer drug delivery system based on folate-conjugated BN nanospheres (BNNS) with receptor-mediated targeting. Folic acid (FA) was successfully grafted onto BNNS via esterification reaction. In vitro cytotoxicity assay showed that BNNS-FA complexes were non-toxic to HeLa cells up to a concentration of 100 μg/mL. Then, doxorubicin hydrochloride (DOX), a commonly used anticancer drug, was loaded onto BNNS-FA complexes. BNNS-FA/DOX complexes were stable at pH 7.4 but effectively released DOX at pH 5.0, which exhibited a pH sensitive and sustained release pattern. BNNS-FA/DOX complexes could be recognized and specifically internalized by HeLa cells via FA receptor-mediated endocytosis. BNNS-FA/DOX complexes exhibited greater cytotoxicity to HeLa cells than free DOX and BNNS/DOX complexes due to the increased cellular uptake of DOX mediated by the FA receptor. Therefore, BNNS-FA complexes had strong potential for targeted cancer therapy.

Structural and Functional Studies of H. seropedicae RecA Protein - Insights into the Polymerization of RecA Protein as Nucleoprotein Filament.

PubMed

Leite, Wellington C; Galvão, Carolina W; Saab, Sérgio C; Iulek, Jorge; Etto, Rafael M; Steffens, Maria B R; Chitteni-Pattu, Sindhu; Stanage, Tyler; Keck, James L; Cox, Michael M

2016-01-01

The bacterial RecA protein plays a role in the complex system of DNA damage repair. Here, we report the functional and structural characterization of the Herbaspirillum seropedicae RecA protein (HsRecA). HsRecA protein is more efficient at displacing SSB protein from ssDNA than Escherichia coli RecA protein. HsRecA also promotes DNA strand exchange more efficiently. The three dimensional structure of HsRecA-ADP/ATP complex has been solved to 1.7 Å resolution. HsRecA protein contains a small N-terminal domain, a central core ATPase domain and a large C-terminal domain, that are similar to homologous bacterial RecA proteins. Comparative structural analysis showed that the N-terminal polymerization motif of archaeal and eukaryotic RecA family proteins are also present in bacterial RecAs. Reconstruction of electrostatic potential from the hexameric structure of HsRecA-ADP/ATP revealed a high positive charge along the inner side, where ssDNA is bound inside the filament. The properties of this surface may explain the greater capacity of HsRecA protein to bind ssDNA, forming a contiguous nucleoprotein filament, displace SSB and promote DNA exchange relative to EcRecA. Our functional and structural analyses provide insight into the molecular mechanisms of polymerization of bacterial RecA as a helical nucleoprotein filament.

Steric hindrance and the enhanced stability of light rare-earth elements in hydrothermal fluids

USGS Publications Warehouse

Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

2009-01-01

A series of X-ray absorption spectroscopy (XAS) experiments were made to determine the structure and stability of aqueous REE (La, Nd, Gd, and Yb) chloride complexes to 500 ??C and 520 MPa. The REE3+ ions exhibit inner-sphere chloroaqua complexation with a steady increase of chloride coordination with increasing temperature in the 150 to 500 ??C range. Furthermore, the degree of chloride coordination of REE3+ inner-sphere chloroaqua complexes decreases significantly from light to heavy REE. These results indicate that steric hindrance drives the reduction of chloride coordination of REE3+ inner-sphere chloroaqua complexes from light to heavy REE. This results in greater stability and preferential transport of light REE3+ over heavy REE3+ ions in saline hydrothermal fluids. Accordingly, the preferential mobility of light REE directly influences the relative abundance of REE in rocks and minerals and thus needs to be considered in geochemical modeling of petrogenetic and ore-forming processes affected by chloride-bearing hydrothermal fluids.

Tectonics, recent geodynamics and seismicity of Azerbaijan part of the Greater Caucasus

NASA Astrophysics Data System (ADS)

Aliyev, Fuad; Kangarli, Talat; Rahimov, Fuad; Murtuzov, Zaur; Aliyev, Ziya

2016-04-01

Transition area of the Eastern Caucasus - Caspian Megadepression corresponds to a periclinal submergence zone of the mountain folded structure of the Greater Caucasus under Pliocene-Holocenic sedimentary complex of Caspian megabasin. Being a part of Alpine-Himalayan folded belt, Greater Caucasus has formed during alpine stage of tectogenesis under geodynamic conditions of convergent interactions between Northern and Southern Caucasus continental microplates. This process has been accompanied by pseudosubduction of the first plate under the second with formation of allochtonous accretion prism above underthrust zone. Modern folding and napping structure of the orogeny has formed as a result of the horizontal movements of different phases and subphases of alpine tectogenesis, that are presented represented by Late Cimmerian - Wallachian tectonic phases within Azerbaijan territory. Limited by meridional fault-slip zones, Caspian megadepression present itself as a young structure that layered on sublatitudinal convergent zone and developed during Late Miocene (10 million years ago) as a flexure zone between two indenters which actively move northward provoking their separation from the African continent and Arabian plate in the west and secession from Central Iranian plate of the Lut block in the east. The acting movement of Arabian plate to the north results in accumulation of the horizontal stress at the current stage of tectogenesis. Current process reveals itself both in the fragmentation of Southern and Northern Caucasus continental microplates into various-size blocks along the general and anti-Caucasus trended faults, and in consideration horizontal and vertical movements within the convergence zone. All these factors define the complexity of geodynamic condition revealed here, in which seismic activity of a transition zone become apparent. There exist the seismic zones here that are confined both to a convergence line and to the fault zones that confine Caspian megadepression or complicate its' inner structure. Under lateral compression conditions, the small-size dynamic blocks that form the inner structure of the earth crust in a transition zone is standing as a reason of formation of the transpressive deformations, which combine moving along bordering of transversal dislocations with the compression structures like Main Caucasus strike faults in a trend of convergent (pseudosubduction) interaction of Southern and Northern Caucasus continental microplates. During such regime a multiple elastic stress accumulation zones are developing, that are confined to mentioned dislocations and their connection knots. Namely, exceeding of a breakage point of the rocks by accumulated elastic deformations, results in earthquakes and destructions in such tectonically vulnerable transition zones.

Deep brain stimulation enhances movement complexity during gait in individuals with Parkinson's disease.

PubMed

Powell, Douglas W; Blackmore, Sarah E; Puppa, Melissa; Lester, Deranda; Murray, Nicholas G; Reed-Jones, Rebecca J; Xia, Rui-Ping

2018-05-08

Deep brain stimulation (DBS) is associated with substantial improvements in motor symptoms of PD. Emerging evidence has suggested that nonlinear measures of complexity may provide greater insight into the efficacy of anti-PD treatments. This study investigated sample entropy and complexity index values in individuals with PD when DBS was OFF compared to ON. Five individuals with PD using DBS performed a four-minute treadmill walking task while 3D kinematics were collected over two periods of 30 s. Participants were tested in the DBS-ON and DBS-OFF conditions. Sample entropy (SE) and complexity index (CI) values were calculated for ankle, knee and hip joint angles. Paired samples t-tests were used to compare mean SE and CI values between the DBS-OFF and DBS-ON conditions, respectively. No differences in SE or CI were observed between the DBS-ON and DBS-OFF conditions at the ankle. At the knee, the DBS-ON was associated with greater SE and CI values than the DBS-OFF condition. At the hip, DBS-ON was associated with greater SE and CI values than the DBS-OFF condition. DBS enhances complexity of movement at the hip and knee joints while complexity at the ankle joint is not significantly altered. Greater complexity of knee and hip joint motion may represent increased adaptability and a greater number of available strategies to complete the gait task. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhancing Bottom-up and Top-down Proteomic Measurements with Ion Mobility Separations

DOE PAGES

Baker, Erin Shammel; Burnum-Johnson, Kristin E.; Ibrahim, Yehia M.; ...

2015-07-03

Proteomic measurements with greater throughput, sensitivity and additional structural information enhance the in-depth characterization of complex mixtures and targeted studies with additional information and higher confidence. While liquid chromatography separation coupled with mass spectrometry (LC-MS) measurements have provided information on thousands of proteins in different sample types, the additional of another rapid separation stage providing structural information has many benefits for analyses. Technical advances in ion funnels and multiplexing have enabled ion mobility separations to be easily and effectively coupled with LC-MS proteomics to enhance the information content of measurements. Finally, herein, we report on applications illustrating increased sensitivity, throughput,more » and structural information by utilizing IMS-MS and LC-IMS-MS measurements for both bottom-up and top-down proteomics measurements.« less

Trapping of light by metal arrays

NASA Astrophysics Data System (ADS)

Khardikov, Vyacheslav V.; Iarko, Ekaterina O.; Prosvirnin, Sergey L.

2010-04-01

The problem of the near-IR light reflection from and transmittance through a planar 2D periodic metal-dielectric structure with a square periodic cell of two complex-shaped asymmetric metal elements has been solved. Conditions of the light confinement by excitation of the trapped mode resonances in certain structures, both polarization-sensitive and polarization-insensitive, were studied. For the first time, the existence of a high-order trapped mode resonance with the greater quality factor than that of the lowest one has been shown. It was ascertained that the Babinet principle provides a good prediction of the resonance properties of the complementary structures, despite the very high Joule losses in the metal strips in near-IR, a finite thickness of the metal elements and the presence of a dielectric substrate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cody, Vivian, E-mail: cody@hwi.buffalo.edu; University of Buffalo, Buffalo, NY 14260; Pace, Jim

The structures of mouse DHFR holo enzyme and a ternary complex with NADPH and a potent inhibitor are described. It has been shown that 2, 4-diamino-6-arylmethylpteridines and 2, 4-diamino-5-arylmethylpyrimidines containing an O-carboxylalkyloxy group in the aryl moiety are potent and selective inhibitors of the dihydrofolate reductase (DHFR) from opportunistic pathogens such as Pneumocystis carinii, the causative agent of Pneumocystis pneumonia in HIV/AIDS patients. In order to understand the structure–activity profile observed for a series of substituted dibenz[b, f]azepine antifolates, the crystal structures of mouse DHFR (mDHFR; a mammalian homologue) holo and ternary complexes with NADPH and the inhibitor 2, 4-diamino-6-(2′-hydroxydibenz[b,more » f]azepin-5-yl)methylpteridine were determined to 1.9 and 1.4 Å resolution, respectively. Structural data for the ternary complex with the potent O-(3-carboxypropyl) inhibitor PT684 revealed no electron density for the O-carboxylalkyloxy side chain. The side chain was either cleaved or completely disordered. The electron density fitted the less potent hydroxyl compound PT684a. Additionally, cocrystallization of mDHFR with NADPH and the less potent 2′-(4-carboxybenzyl) inhibitor PT682 showed no electron density for the inhibitor and resulted in the first report of a holoenzyme complex despite several attempts at crystallization of a ternary complex. Modeling data of PT682 in the active site of mDHFR and P. carinii DHFR (pcDHFR) indicate that binding would require ligand-induced conformational changes to the enzyme for the inhibitor to fit into the active site or that the inhibitor side chain would have to adopt an alternative binding mode to that observed for other carboxyalkyloxy inhibitors. These data also show that the mDHFR complexes have a decreased active-site volume as reflected in the relative shift of helix C (residues 59–64) by 0.6 Å compared with pcDHFR ternary complexes. These data are consistent with the greater inhibitory potency against pcDHFR.« less

Using a Qualitative Vignette to Explore a Complex Public Health Issue.

PubMed

Jackson, Michaela; Harrison, Paul; Swinburn, Boyd; Lawrence, Mark

2015-10-01

This article discusses how qualitative vignettes were combined with interviews to explore a complex public health issue; that is, promoting unhealthy foods and beverages to children and adolescents. It outlines how the technique was applied in practice and the combination of vignette-based interviews with a broader approach involving Gadamerian hermeneutics. Twenty-one participants from the public health community and the marketing and food and beverage industries took part in vignette-based interviews between March and September 2012. Overall, the qualitative vignette method afforded an efficient, generally well-received technique that effectively explored the issue of promoting unhealthy foods and beverages to children and adolescents. The vignette provided structure to interviews but allowed certain responses to be investigated in greater depth. Through this research, we argue that qualitative vignettes allow researchers to explore complex public health issues. This article also provides a valuable resource for researchers seeking to explore this technique. © The Author(s) 2015.

Collective Autoionization in Multiply-Excited Systems: A novel ionization process observed in Helium Nanodroplets

PubMed Central

LaForge, A. C.; Drabbels, M.; Brauer, N. B.; Coreno, M.; Devetta, M.; Di Fraia, M.; Finetti, P.; Grazioli, C.; Katzy, R.; Lyamayev, V.; Mazza, T.; Mudrich, M.; O'Keeffe, P.; Ovcharenko, Y.; Piseri, P.; Plekan, O.; Prince, K. C.; Richter, R.; Stranges, S.; Callegari, C.; Möller, T.; Stienkemeier, F.

2014-01-01

Free electron lasers (FELs) offer the unprecedented capability to study reaction dynamics and image the structure of complex systems. When multiple photons are absorbed in complex systems, a plasma-like state is formed where many atoms are ionized on a femtosecond timescale. If multiphoton absorption is resonantly-enhanced, the system becomes electronically-excited prior to plasma formation, with subsequent decay paths which have been scarcely investigated to date. Here, we show using helium nanodroplets as an example that these systems can decay by a new type of process, named collective autoionization. In addition, we show that this process is surprisingly efficient, leading to ion abundances much greater than that of direct single-photon ionization. This novel collective ionization process is expected to be important in many other complex systems, e.g. macromolecules and nanoparticles, exposed to high intensity radiation fields. PMID:24406316

Rapid assessment of the antigenic integrity of tetrameric HLA complexes by human monoclonal HLA antibodies.

PubMed

Eijsink, Chantal; Kester, Michel G D; Franke, Marry E I; Franken, Kees L M C; Heemskerk, Mirjam H M; Claas, Frans H J; Mulder, Arend

2006-08-31

The ability of tetrameric major histocompatibility complex (MHC) class I-peptide complexes (tetramers) to detect antigen-specific T lymphocyte responses has yielded significant information about the generation of in vivo immunity in numerous antigenic systems. Here we present a novel method for rapid validation of tetrameric HLA molecules based on the presence of allodeterminants. Human monoclonal antibodies (mAbs) recognizing polymorphic determinants on HLA class I were immobilized on polystyrene microparticles and used to probe the structural integrity of tetrameric HLA class I molecules by flow cytometry. A total of 22 tetramers, based on HLA-A1, A2, A3, A24, B7 and B8 were reactive with their counterpart mAbs, thus confirming their antigenic integrity. A positive outcome of this mAb test ensures that tetrameric HLA class I can be used with greater confidence in subsequent functional assays.

Pure electronic metal-insulator transition at the interface of complex oxides

DOE PAGES

Meyers, D.; Liu, Jian; Freeland, J. W.; ...

2016-06-21

We observed complex materials in electronic phases and transitions between them often involve coupling between many degrees of freedom whose entanglement convolutes understanding of the instigating mechanism. Metal-insulator transitions are one such problem where coupling to the structural, orbital, charge, and magnetic order parameters frequently obscures the underlying physics. We demonstrate a way to unravel this conundrum by heterostructuring a prototypical multi-ordered complex oxide NdNiO3 in ultra thin geometry, which preserves the metal-to-insulator transition and bulk-like magnetic order parameter, but entirely suppresses the symmetry lowering and long-range charge order parameter. Furthermore, these findings illustrate the utility of heterointerfaces as amore » powerful method for removing competing order parameters to gain greater insight into the nature of the transition, here revealing that the magnetic order generates the transition independently, leading to an exceptionally rare purely electronic metal-insulator transition with no symmetry change.« less

Microwave Spectra and Structure of {H_2-CuF}: Overview of the Complexes of Hydrogen with Metal-Containing Diatomics

NASA Astrophysics Data System (ADS)

Grubbs, G. S. Grubbs, Ii; Frohman, Daniel J.; Yu, Zhenhong; Novick, Stewart E.

2013-06-01

We present here the FTMW spectra of the various isotopologues of the intermediate strength bound complex of dihydrogen with copper fluoride. The bond between the two moieties is surprisingly strong, the H-H forming the cross of the T with the Cu closest to H_2 in the C_{{2v}} structure. Laser ablation was used to produce both copper isotopologues of p-H_2-CuF, o-D_2-CuF, and HD-CuF whose J = 1 - 0 transitions were observed. Significant changes in the nuclear quadrupole coupling constants for the copper nucleus in H_2-CuF compared to that in uncomplexed CuF suggests bonding greater than that typical of van der Waals interactions. This talk will serve as the introduction to presentations at this meeting of other H_2 metal containing diatomics. D. J. Frohman, {G. S. Grubbs II}, Z. Yu, S. E. Novick, Inorg. Chem., 52, 816-822 (2013).

In vitro digestion and physicochemical characteristics of corn starch mixed with amino acid modified by low pressure treatment.

PubMed

Ji, Ying

2018-03-01

The digestibility and molecular structure of corn starch mixed with amino acid modified by low-pressure treatment (LPT) was investigated. Amino acid induced a significant increase in the slowly digestible starch (SDS) and decrease in the rapidly digestible starch (RDS) after LPT. The reason is the formation of ester bond between the molecular chains of amino acid and starch. Low pressure treatment altered greatly the morphology of corn starch mixed with or without amino acid. After LPT, less ordered Maltese and more granule fragments were observed for starch-amino acid complex. An increase in size distribution was obvious after LPT and the size distribution curves provided from a new variety. We found that higher enthalpy and relative crystallinity of the starch-amino acid complex were associated with a higher SDS content. It can be inferred that LPT had a greater impact on the digestion and structural characterization of corn starch mixed with amino acids. Copyright © 2017 Elsevier Ltd. All rights reserved.

Patent information - towards simplicity or complexity?

NASA Astrophysics Data System (ADS)

Shenton, Written By Kathleen; Norton, Peter; Onodera, Translated By Natsuo

Since the advent of online services, the ability to search and find chemical patent information has improved immeasurably. Recently, integration of a multitude of files (through file merging as well as cross-file/simultaneous searches), 'intelligent' interfaces and optical technology for large amounts of data seem to achieve greater simplicity and convenience in the retrieval of patent information. In spite of these progresses, there is more essential problem which increases complexity. It is a tendency to expand indefinitely the range of claim for chemical substances by a ultra-generic description of structure (overuse of optional substituents, variable divalent groups, repeating groups, etc.) and long listing of prophetic examples. Not only does this tendency worry producers and searchers of patent databases but also prevents truly worthy inventions in future.

The adhesion and hysteresis effect in friction skin with artificial materials

NASA Astrophysics Data System (ADS)

Subhi, K. A.; Tudor, A.; Hussein, E. K.; Wahad, H. S.

2017-02-01

Human skin is a soft biomaterial with a complex anatomical structure and it has a complex material behavior during the mechanical contact with objects and surfaces. The friction adhesion component is defined by means of the theories of Johnson-Kendall-Roberts (JKR), Derjaguin-Muller-Toporov (DMT) and Maugis - Dugdale (MD). We shall consider the human skin entering into contact with a rigid surface. The deformation (hysteresis) component of the skin friction is evaluated with Voigt rheological model for the spherical contact, with the original model, developed in MATHCAD software. The adhesive component of the skin friction is greater than the hysteresis component for all friction parameters (load, velocity, the strength of interface between skin and the artificial material).

Shelters and Their Use by Fishes on Fringing Coral Reefs

PubMed Central

Ménard, Alexandre; Turgeon, Katrine; Roche, Dominique G.; Binning, Sandra A.; Kramer, Donald L.

2012-01-01

Coral reef fish density and species richness are often higher at sites with more structural complexity. This association may be due to greater availability of shelters, but surprisingly little is known about the size and density of shelters and their use by coral reef fishes. We quantified shelter availability and use by fishes for the first time on a Caribbean coral reef by counting all holes and overhangs with a minimum entrance diameter ≥3 cm in 30 quadrats (25 m2) on two fringing reefs in Barbados. Shelter size was highly variable, ranging from 42 cm3 to over 4,000,000 cm3, with many more small than large shelters. On average, there were 3.8 shelters m−2, with a median volume of 1,200 cm3 and a total volume of 52,000 cm3m−2. The number of fish per occupied shelter ranged from 1 to 35 individual fishes belonging to 66 species, with a median of 1. The proportion of shelters occupied and the number of occupants increased strongly with shelter size. Shelter density and total volume increased with substrate complexity, and this relationship varied among reef zones. The density of shelter-using fish was much more strongly predicted by shelter density and median size than by substrate complexity and increased linearly with shelter density, indicating that shelter availability is a limiting resource for some coral reef fishes. The results demonstrate the importance of large shelters for fish density and support the hypothesis that structural complexity is associated with fish abundance, at least in part, due to its association with shelter availability. This information can help identify critical habitat for coral reef fishes, predict the effects of reductions in structural complexity of natural reefs and improve the design of artificial reefs. PMID:22745664

Fractal structures and fractal functions as disease indicators

USGS Publications Warehouse

Escos, J.M; Alados, C.L.; Emlen, J.M.

1995-01-01

Developmental instability is an early indicator of stress, and has been used to monitor the impacts of human disturbance on natural ecosystems. Here we investigate the use of different measures of developmental instability on two species, green peppers (Capsicum annuum), a plant, and Spanish ibex (Capra pyrenaica), an animal. For green peppers we compared the variance in allometric relationship between control plants, and a treatment group infected with the tomato spotted wilt virus. The results show that infected plants have a greater variance about the allometric regression line than the control plants. We also observed a reduction in complexity of branch structure in green pepper with a viral infection. Box-counting fractal dimension of branch architecture declined under stress infection. We also tested the reduction in complexity of behavioral patterns under stress situations in Spanish ibex (Capra pyrenaica). Fractal dimension of head-lift frequency distribution measures predator detection efficiency. This dimension decreased under stressful conditions, such as advanced pregnancy and parasitic infection. Feeding distribution activities reflect food searching efficiency. Power spectral analysis proves to be the most powerful tool for character- izing fractal behavior, revealing a reduction in complexity of time distribution activity under parasitic infection.

Eastern mosquitofish resists invasion by nonindigenous poeciliids through agonistic behaviors

USGS Publications Warehouse

Thompson, Kevin A.; Hill, Jeffrey E.; Nico, Leo G.

2012-01-01

Florida is a hotspot for nonindigenous fishes with over 30 species established, although few of these are small-bodied species. One hypothesis for this pattern is that biotic resistance of native species is reducing the success of small-bodied, introduced fishes. The eastern mosquitofish Gambusia holbrooki is common in many freshwater habitats in Florida and although small-bodied (<50 mm), it is a predator and aggressive competitor. We conducted four mesocosm experiments to examine the potential for biotic resistance by eastern mosquitofish to two small-bodied nonindigenous fishes, variable platyfish (Xiphophorus variatus) and swordtail (X. hellerii). Experiments tested: (1) effect of eastern mosquitofish density on adult survival, (2) effect of eastern mosquitofish on a stage-structured population, (3) role of habitat structural complexity on nonindigenous adult survival, and (4) behavioral effects of eastern mosquitofish presence and habitat complexity. Eastern mosquitofish attacked and killed non-native poeciliids with especially strong effects on juveniles of both species. Higher eastern mosquitofish density resulted in greater effects. Predation on swordtails increased with increasing habitat complexity. Eastern mosquitofish also actively drove swordtails from cover, which could expose non-native fish to other predators under field conditions. Our results suggest that eastern mosquitofish may limit invasion success.

Structure, energetics and vibrational spectra of dimers, trimers, and tetramers of HX (X = Cl, Br, I)

NASA Astrophysics Data System (ADS)

Latajka, Zdzislaw; Scheiner, Steve

1997-03-01

The title complexes are studied by correlated ab initio methods using a pseudopotential double-ζ basis set, augmented by diffuse sp and two sets of polarization functions. The binding energies of the complexes decrease in the order HCl > HBr > HI. In the mixed HX…HX' dimers, the nature of the proton-donor molecule is more important than is the proton-acceptor with respect to the strength of the interaction. Only one minimum is found on the potential energy surface of the trimers and tetramers, which corresponds to the C nh cyclic structure. Enlargement of the complex leads to progressively greater individual H-bond energy and HX bond stretch, coupled with reduced intermolecular separation and smaller nonlinearity of each H-bond. Electron correlation makes a larger contribution as the atomic number of X increases. The highest degree of cooperativity is noted for oligomers of HCl and HBr, as compared to HI. The nonadditivity is dominated by terms present at the SCF level. The vibrational frequencies exhibit trends that generally parallel the energetics and geometry patterns, particularly the red shifts of the HX stretches and the intermolecular modes.

Competitive pressures affect sexual signal complexity in Kurixalus odontotarsus: insights into the evolution of compound calls

PubMed Central

2017-01-01

ABSTRACT Male-male vocal competition in anuran species is critical for mating success; however, it is also energetically demanding and highly time-consuming. Thus, we hypothesized that males may change signal elaboration in response to competition in real time. Male serrate-legged small treefrogs (Kurixalus odontotarsus) produce compound calls that contain two kinds of notes, harmonic sounds called ‘A notes’ and short broadband sounds called ‘B notes’. Using male evoked vocal response experiments, we found that competition influences the temporal structure and complexity of vocal signals produced by males. Males produce calls with a higher ratio of notes:call, and more compound calls including more A notes but fewer B notes with contest escalation. In doing so, males minimize the energy costs and maximize the benefits of competition when the level of competition is high. This means that the evolution of sexual signal complexity in frogs may be susceptible to selection for plasticity related to adjusting performance to the pressures of competition, and supports the idea that more complex social contexts can lead to greater vocal complexity. PMID:29175862

Concept Maps for Improved Science Reasoning and Writing: Complexity Isn’t Everything

PubMed Central

Dowd, Jason E.; Duncan, Tanya; Reynolds, Julie A.

2015-01-01

A pervasive notion in the literature is that complex concept maps reflect greater knowledge and/or more expert-like thinking than less complex concept maps. We show that concept maps used to structure scientific writing and clarify scientific reasoning do not adhere to this notion. In an undergraduate course for thesis writers, students use concept maps instead of traditional outlines to define the boundaries and scope of their research and to construct an argument for the significance of their research. Students generate maps at the beginning of the semester, revise after peer review, and revise once more at the end of the semester. Although some students revised their maps to make them more complex, a significant proportion of students simplified their maps. We found no correlation between increased complexity and improved scientific reasoning and writing skills, suggesting that sometimes students simplify their understanding as they develop more expert-like thinking. These results suggest that concept maps, when used as an intervention, can meet the varying needs of a diverse population of student writers. PMID:26538388

Phenotypic integration emerges from aposematism and scale in poison frogs

PubMed Central

Santos, Juan C.; Cannatella, David C.

2011-01-01

Complex phenotypes can be modeled as networks of component traits connected by genetic, developmental, or functional interactions. Aposematism, which has evolved multiple times in poison frogs (Dendrobatidae), links a warning signal to a chemical defense against predators. Other traits are involved in this complex phenotype. Most aposematic poison frogs are ant specialists, from which they sequester defensive alkaloids. We found that aposematic species have greater aerobic capacity, also related to diet specialization. To characterize the aposematic trait network more fully, we analyzed phylogenetic correlations among its hypothesized components: conspicuousness, chemical defense, diet specialization, body mass, active and resting metabolic rates, and aerobic scope. Conspicuous coloration was correlated with all components except resting metabolism. Structural equation modeling on the basis of trait correlations recovered “aposematism” as one of two latent variables in an integrated phenotypic network, the other being scaling with body mass and physiology (“scale”). Chemical defense and diet specialization were uniquely tied to aposematism whereas conspicuousness was related to scale. The phylogenetic distribution of the aposematic syndrome suggests two scenarios for its evolution: (i) chemical defense and conspicuousness preceded greater aerobic capacity, which supports the increased resource-gathering abilities required of ant–mite diet specialization; and (ii) assuming that prey are patchy, diet specialization and greater aerobic capacity evolved in tandem, and both traits subsequently facilitated the evolution of aposematism. PMID:21444790

PERMANGANATE FIXATION OF THE GOLGI COMPLEX AND OTHER CYTOPLASMIC STRUCTURES OF MAMMALIAN TESTES

PubMed Central

Mollenhauer, Hilton H.; Zebrun, William

1960-01-01

Observations on the fine structure of KMnO4-fixed testes of small mammals (guinea pig, rat, and mouse) reveal certain morphological differences between the spermatogenic and Sertoli cells which have not been demonstrated in the same tissue fixed with OsO4. Aggregates of minute circular profiles, much smaller than the spherical Golgi vesicles, are described in close association with the Golgi complex of developing spermatids. Groups of dense flattened vesicles, individually surrounded by a membrane of different dimensions than that which bounds most of the other cell organelles, appear dispersed within the cytoplasm of some spermatogenic cells. Flattened vesicles of greater density than those belonging to the Golgi complex are reported confined to the inner Golgi zone of developing guinea pig spermatids between the Golgi cisternae and the head cap. The profiles of endoplasmic reticulum within spermatocytes appear shorter, wider, and more tortuous than those of Sertoli cells. Minute cytoplasmic particles approximately 300 A in diameter and of high electron opacity appear randomly disposed in some Sertoli cells. Groups of irregular-shaped ovoid bodies within the developing spermatids are described as resembling portions of cytoplasm from closely adjacent spermatids. Interpretation is presented regarding the fine structure of KMnO4-fixed testes in view of what has already been reported for mammalian testes fixed in OsO4. PMID:13771855

Health behavior change models for HIV prevention and AIDS care: practical recommendations for a multi-level approach.

PubMed

Kaufman, Michelle R; Cornish, Flora; Zimmerman, Rick S; Johnson, Blair T

2014-08-15

Despite increasing recent emphasis on the social and structural determinants of HIV-related behavior, empirical research and interventions lag behind, partly because of the complexity of social-structural approaches. This article provides a comprehensive and practical review of the diverse literature on multi-level approaches to HIV-related behavior change in the interest of contributing to the ongoing shift to more holistic theory, research, and practice. It has the following specific aims: (1) to provide a comprehensive list of relevant variables/factors related to behavior change at all points on the individual-structural spectrum, (2) to map out and compare the characteristics of important recent multi-level models, (3) to reflect on the challenges of operating with such complex theoretical tools, and (4) to identify next steps and make actionable recommendations. Using a multi-level approach implies incorporating increasing numbers of variables and increasingly context-specific mechanisms, overall producing greater intricacies. We conclude with recommendations on how best to respond to this complexity, which include: using formative research and interdisciplinary collaboration to select the most appropriate levels and variables in a given context; measuring social and institutional variables at the appropriate level to ensure meaningful assessments of multiple levels are made; and conceptualizing intervention and research with reference to theoretical models and mechanisms to facilitate transferability, sustainability, and scalability.

The sequential structure of brain activation predicts skill.

PubMed

Anderson, John R; Bothell, Daniel; Fincham, Jon M; Moon, Jungaa

2016-01-29

In an fMRI study, participants were trained to play a complex video game. They were scanned early and then again after substantial practice. While better players showed greater activation in one region (right dorsal striatum) their relative skill was better diagnosed by considering the sequential structure of whole brain activation. Using a cognitive model that played this game, we extracted a characterization of the mental states that are involved in playing a game and the statistical structure of the transitions among these states. There was a strong correspondence between this measure of sequential structure and the skill of different players. Using multi-voxel pattern analysis, it was possible to recognize, with relatively high accuracy, the cognitive states participants were in during particular scans. We used the sequential structure of these activation-recognized states to predict the skill of individual players. These findings indicate that important features about information-processing strategies can be identified from a model-based analysis of the sequential structure of brain activation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Singularities in Optimal Structural Design

NASA Technical Reports Server (NTRS)

Patnaik, S. N.; Guptill, J. D.; Berke, L.

1992-01-01

Singularity conditions that arise during structural optimization can seriously degrade the performance of the optimizer. The singularities are intrinsic to the formulation of the structural optimization problem and are not associated with the method of analysis. Certain conditions that give rise to singularities have been identified in earlier papers, encompassing the entire structure. Further examination revealed more complex sets of conditions in which singularities occur. Some of these singularities are local in nature, being associated with only a segment of the structure. Moreover, the likelihood that one of these local singularities may arise during an optimization procedure can be much greater than that of the global singularity identified earlier. Examples are provided of these additional forms of singularities. A framework is also given in which these singularities can be recognized. In particular, the singularities can be identified by examination of the stress displacement relations along with the compatibility conditions and/or the displacement stress relations derived in the integrated force method of structural analysis.

Singularities in optimal structural design

NASA Technical Reports Server (NTRS)

Patnaik, S. N.; Guptill, J. D.; Berke, L.

1992-01-01

Singularity conditions that arise during structural optimization can seriously degrade the performance of the optimizer. The singularities are intrinsic to the formulation of the structural optimization problem and are not associated with the method of analysis. Certain conditions that give rise to singularities have been identified in earlier papers, encompassing the entire structure. Further examination revealed more complex sets of conditions in which singularities occur. Some of these singularities are local in nature, being associated with only a segment of the structure. Moreover, the likelihood that one of these local singularities may arise during an optimization procedure can be much greater than that of the global singularity identified earlier. Examples are provided of these additional forms of singularities. A framework is also given in which these singularities can be recognized. In particular, the singularities can be identified by examination of the stress displacement relations along with the compatibility conditions and/or the displacement stress relations derived in the integrated force method of structural analysis.

Neutron reflectometry as a tool to study magnetism.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Felcher, G. P.

1999-09-21

Polarized-neutron specular reflectometry (PNR) was developed in the 1980's as a means of measuring magnetic depth profiles in flat films. Starting from simple profiles, and gradually solving structures of greater complexity, PNR has been used to observe or clarify a variety of magnetic phenomena. It has been used to measure the absolute magnetization of films of thickness not exceeding a few atomic planes, the penetration of magnetic fields in micron-thick superconductors, and the detailed magnetic coupling across non-magnetic spacers in multilayers and superlattices. Although PNR is considered a probe of depth dependent magnetic structure, laterally averaged in the plane ofmore » the film, the development of new scattering techniques promises to enable the characterization of lateral magnetic structures. Retaining the depth-sensitivity of specular reflectivity, off-specular reflectivity may be brought to resolve in-plane structures over nanometer to micron length scales.« less

Coping with Prescription Drug Cost Sharing: Knowledge, Adherence, and Financial Burden

PubMed Central

Reed, Mary; Brand, Richard; Newhouse, Joseph P; Selby, Joe V; Hsu, John

2008-01-01

Objective Assess patient knowledge of and response to drug cost sharing. Study Setting Adult members of a large prepaid, integrated delivery system. Study Design/Data Collection Telephone interviews with 932 participants (72 percent response rate) who reported knowledge of the structures and amounts of their prescription drug cost sharing. Participants reported cost-related changes in their drug adherence, any financial burden, and other cost-coping behaviors. Actual cost sharing amounts came from administrative databases. Principal Findings Overall, 27 percent of patients knew all of their drug cost sharing structures and amounts. After adjustment for individual characteristics, additional patient cost sharing structures (tiers and caps), and higher copayment amounts were associated with reporting decreased adherence, financial burden, or other cost-coping behaviors. Conclusions Patient knowledge of their drug benefits is limited, especially for more complex cost sharing structures. Patients also report a range of responses to greater cost sharing, including decreasing adherence. PMID:18370979

Crystal Structure of Allophycocyanin from Marine Cyanobacterium Phormidium sp. A09DM

PubMed Central

Gupta, Gagan Deep; Madamwar, Datta

2015-01-01

Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography analysis to obtain greater insights into the structure-function relationship of this light harvesting complex. Allophycocyanin (APC) is the phycobiliprotein always found in the PBS core complex. Phycocyanobilin (PCB) chromophores, covalently bound to conserved Cys residues of α- and β- subunits of APC, are responsible for solar energy absorption from phycocyanin and for transfer to photosynthetic apparatus. In the known APC structures, heterodimers of α- and β- subunits (known as αβ monomers) assemble as trimer or hexamer. We here for the first time report the crystal structure of APC isolated from a marine cyanobacterium (Phormidium sp. A09DM). The crystal structure has been refined against all the observed data to the resolution of 2.51 Å to Rwork (Rfree) of 0.158 (0.229) with good stereochemistry of the atomic model. The Phormidium protein exists as a trimer of αβ monomers in solution and in crystal lattice. The overall tertiary structures of α- and β- subunits, and trimeric quaternary fold of the Phormidium protein resemble the other known APC structures. Also, configuration and conformation of the two covalently bound PCB chromophores in the marine APC are same as those observed in fresh water cyanobacteria and marine red algae. More hydrophobic residues, however, constitute the environment of the chromophore bound to α-subunit of the Phormidium protein, owing mainly to amino acid substitutions in the marine protein. PMID:25923120

Predictive model of complexity in early palliative care: a cohort of advanced cancer patients (PALCOM study).

PubMed

Tuca, Albert; Gómez-Martínez, Mónica; Prat, Aleix

2018-01-01

Model of early palliative care (PC) integrated in oncology is based on shared care from the diagnosis to the end of life and is mainly focused on patients with greater complexity. However, there is no definition or tools to evaluate PC complexity. The objectives of the study were to identify the factors influencing level determination of complexity, propose predictive models, and build a complexity scale of PC. We performed a prospective, observational, multicenter study in a cohort of advanced cancer patients with an estimated prognosis ≤ 6 months. An ad hoc structured evaluation including socio-demographic and clinical data, symptom burden, functional and cognitive status, psychosocial problems, and existential-ethic dilemmas was recorded systematically. According to this multidimensional evaluation, investigator classified patients as high, medium, or low palliative complexity, associated to need of basic or specialized PC. Logistic regression was used to identify the variables influencing determination of level of PC complexity and explore predictive models. We included 324 patients; 41% were classified as having high PC complexity and 42.9% as medium, both levels being associated with specialized PC. Variables influencing determination of PC complexity were as follows: high symptom burden (OR 3.19 95%CI: 1.72-6.17), difficult pain (OR 2.81 95%CI:1.64-4.9), functional status (OR 0.99 95%CI:0.98-0.9), and social-ethical existential risk factors (OR 3.11 95%CI:1.73-5.77). Logistic analysis of variables allowed construct a complexity model and structured scales (PALCOM 1 and 2) with high predictive value (AUC ROC 76%). This study provides a new model and tools to assess complexity in palliative care, which may be very useful to manage referral to specialized PC services, and agree intensity of their intervention in a model of early-shared care integrated in oncology.

Crystal structure of CD155 and electron microscopic studies of its complexes with polioviruses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Ping; Mueller, Steffen; Morais, Marc C.

2010-11-02

When poliovirus (PV) recognizes its receptor, CD155, the virus changes from a 160S to a 135S particle before releasing its genome into the cytoplasm. CD155 is a transmembrane protein with 3 Ig-like extracellular domains, D1-D3, where D1 is recognized by the virus. The crystal structure of D1D2 has been determined to 3.5-{angstrom} resolution and fitted into {approx}8.5-{angstrom} resolution cryoelectron microscopy reconstructions of the virus-receptor complexes for the 3 PV serotypes. These structures show that, compared with human rhinoviruses, the virus-receptor interactions for PVs have a greater dependence on hydrophobic interactions, as might be required for a virus that can inhabitmore » environments of different pH. The pocket factor was shown to remain in the virus during the first recognition stage. The present structures, when combined with earlier mutational investigations, show that in the subsequent entry stage the receptor moves further into the canyon when at a physiological temperature, thereby expelling the pocket factor and separating the viral subunits to form 135S particles. These results provide a detailed analysis of how a nonenveloped virus can enter its host cell.« less

Geothermal prospection in the Greater Geneva Basin (Switzerland and France): Structural and reservoir quality assessment

NASA Astrophysics Data System (ADS)

Rusillon, Elme; Clerc, Nicolas; Makhloufi, Yasin; Brentini, Maud; Moscariello, Andrea

2017-04-01

A reservoir assessment was performed in the Greater Geneva Basin to evaluate the geothermal resources potential of low to medium enthalpy (Moscariello, 2016). For this purpose, a detail structural analysis of the basin was performed (Clerc et al., 2016) simultaneously with a reservoir appraisal study including petrophysical properties assessment in a consistent sedimentological and stratigraphical frame (Brentini et al., 2017). This multi-disciplinary study was organised in 4 steps: (1) investigation of the surrounding outcrops to understand the stratigraphy and lateral facies distribution of the sedimentary sequence from Permo-Carboniferous to Lower Cretaceous units; (2) development of 3D geological models derived from 2D seismic and well data focusing on the structural scheme of the basin to constrain better the tectonic influence on facies distribution and to assess potential hydraulic connectivity through faults between reservoir units ; (3) evaluation of the distribution, geometry, sedimentology and petrophysical properties of potential reservoir units from well data; (4) identification and selection of the most promising reservoir units for in-depth rock type characterization and 3D modeling. Petrophysical investigations revealed that the Kimmeridgian-Tithonian Reef Complex and the underlying Calcaires de Tabalcon units are the most promising geothermal reservoir targets (porosity range 10-20%; permeability to 1mD). Best reservoir properties are measured in patch reefs and high-energy peri-reefal depositional environments, which are surrounded by synchronous tight lagoonal deposits. Associated highly porous dolomitized intervals reported in the western part of the basin also provide enhanced reservoir quality. The distribution and geometry of best reservoir bodies is complex and constrained by (1) palaeotopography, which can be affected by synsedimentary fault activity during Mesozoic times, (2) sedimentary factors such as hydrodynamics, sea level variations, or sedimentation rates and (3) diagenetic history (Makhloufi et al., 2017). A detail structural characterization of the basin using 2D seismic data reveals the existence of several wrench fault zones and intra-basinal thrusts across the basin, which could act as hydraulic conduits and play a key role in connecting the most productive reservoir facies. To understand the propagation of these heterogeneous reservoirs, rock types are currently defined and will be integrated into 3D geological models. This integrated study allows us to understand better the distribution and properties of productive reservoir facies as well as hydraulic connectivity zones within the study area. This provides consistent knowledge for future geothermal exploration steps toward the successful development of this sustainable energy resource in the Greater Geneva Basin. Brentini et al. 2017 : Geothermal prospection in the Greater Geneva Basin: integration of geological data in the new Information System. Abstract, EGU General Assembly 2017, Vienna, Austria Clerc et al. 2016 : Structural Modeling of the Geneva Basin for Geothermal Ressource Assessment. Abstract, 14th Swiss Geoscience Meeting, Geneva, Switzerland Makhloufi et al. 2017 : Geothermal prospection in the Greater Geneva Basin (Switzerland and France) : impact of diagenesis on reservoir properties of the Upper Jurassic carbonate sediments. Abstract, EGU General Assembly 2017, Vienna, Austria Moscariello, A. 2016 : Geothermal exploration in SW Switzerland, Proceeding , European Geotermal Congress 2016, Strasbourg, France

Evaluating Treatment and Generalization Patterns of Two Theoretically Motivated Sentence Comprehension Therapies.

PubMed

Des Roches, Carrie A; Vallila-Rohter, Sofia; Villard, Sarah; Tripodis, Yorghos; Caplan, David; Kiran, Swathi

2016-12-01

The current study examined treatment outcomes and generalization patterns following 2 sentence comprehension therapies: object manipulation (OM) and sentence-to-picture matching (SPM). Findings were interpreted within the framework of specific deficit and resource reduction accounts, which were extended in order to examine the nature of generalization following treatment of sentence comprehension deficits in aphasia. Forty-eight individuals with aphasia were enrolled in 1 of 8 potential treatment assignments that varied by task (OM, SPM), complexity of trained sentences (complex, simple), and syntactic movement (noun phrase, wh-movement). Comprehension of trained and untrained sentences was probed before and after treatment using stimuli that differed from the treatment stimuli. Linear mixed-model analyses demonstrated that, although both OM and SPM treatments were effective, OM resulted in greater improvement than SPM. Analyses of covariance revealed main effects of complexity in generalization; generalization from complex to simple linguistically related sentences was observed both across task and across movement. Results are consistent with the complexity account of treatment efficacy, as generalization effects were consistently observed from complex to simpler structures. Furthermore, results provide support for resource reduction accounts that suggest that generalization can extend across linguistic boundaries, such as across movement type.

The Capabilities of Chaos and Complexity

PubMed Central

Abel, David L.

2009-01-01

To what degree could chaos and complexity have organized a Peptide or RNA World of crude yet necessarily integrated protometabolism? How far could such protolife evolve in the absence of a heritable linear digital symbol system that could mutate, instruct, regulate, optimize and maintain metabolic homeostasis? To address these questions, chaos, complexity, self-ordered states, and organization must all be carefully defined and distinguished. In addition their cause-and-effect relationships and mechanisms of action must be delineated. Are there any formal (non physical, abstract, conceptual, algorithmic) components to chaos, complexity, self-ordering and organization, or are they entirely physicodynamic (physical, mass/energy interaction alone)? Chaos and complexity can produce some fascinating self-ordered phenomena. But can spontaneous chaos and complexity steer events and processes toward pragmatic benefit, select function over non function, optimize algorithms, integrate circuits, produce computational halting, organize processes into formal systems, control and regulate existing systems toward greater efficiency? The question is pursued of whether there might be some yet-to-be discovered new law of biology that will elucidate the derivation of prescriptive information and control. “System” will be rigorously defined. Can a low-informational rapid succession of Prigogine’s dissipative structures self-order into bona fide organization? PMID:19333445

Does Supporting Multiple Student Strategies Lead to Greater Learning and Motivation? Investigating a Source of Complexity in the Architecture of Intelligent Tutoring Systems

ERIC Educational Resources Information Center

Waalkens, Maaike; Aleven, Vincent; Taatgen, Niels

2013-01-01

Intelligent tutoring systems (ITS) support students in learning a complex problem-solving skill. One feature that makes an ITS architecturally complex, and hard to build, is support for strategy freedom, that is, the ability to let students pursue multiple solution strategies within a given problem. But does greater freedom mean that students…

Quantifying the social structure of a large captive flock of greater flamingos (Phoenicopterus roseus): Potential implications for management in captivity.

PubMed

Rose, Paul E; Croft, Darren P

2018-05-01

An appropriate social environment for species held in captivity is key for ensuring both good welfare and reproductive performance. Species with a complex social structure may suffer if their social requirements are not taken into consideration as part of management and husbandry strategies. Here we aim to understand the drivers of social structure, and the link between social structure and reproduction in a flock of 281 greater flamingos (Phoenicopterus roseus) at WWT Slimbridge Wetland Centre. Proximity-based associations between birds were measured three and four times per day (depending upon season and husbandry) from 2012 to 2016. To determine the effect of reproductive activity on social structure, display and nesting behaviour were also recorded for the 2015 breeding season (April-July). Results showed that birds displayed a wider range of social relationships, and that affiliations within the flock were not random. This flamingo flock was differentiated into discrete subgroups, and social structure was stable across some years, but not over all seasons. Social bonds were more consistent across seasons into the nesting period rather than outside of it. During breeding, not all birds that displayed built a nest, and not all displaying birds nested. Future research should further investigate differences in display and nesting patterns within a flock, and determine how the social structure of large flocks compares to smaller flocks of this species. Comparing captive data to information on wild bird sociality would be relevant to highlight any differences in patterns of assortment and connectivity. Copyright © 2018 Elsevier B.V. All rights reserved.

The Rise of Complexity: Do the Pavilion Lake Microbialites Suggest a Way to Build a Macroorganism?

NASA Astrophysics Data System (ADS)

Schulze-Makuch, D.; Laval, B.; Lim, D. S.; Irwin, L. N.

2005-12-01

The distinctive assemblage of freshwater calcite microbialites discovered at Pavilion Lake, BC, has been associated with organisms such as Epiphyton and Girvanella, fossils from just before the Cambrian explosion about 550 million years ago (Laval et al., 2000). The presence of the microbialite structures in a dimictic mid-latitude lake and their establishment after the last ice age about 10,000 years ago is puzzling. Their distinctive morphologies include cone-shaped seepage structures 2 m or more in height with hollow internal conduits that open at the top of the cones, and dense artichoke-like structures with calcite "leaves" greater than 1 m in height. These structures are astounding as they imply functional properties. In principle, this is not unlike the interaction of individual cells in a macroorganism, in which many different types of specialized cells interact with each other to the benefit of the whole organism (e.g. interaction of blood, integument, and organ cells within animals). Certainly, the complex interaction of these microbial cells is not equivalent to the collaboration of cells within an individual multicellular organism, where each cell has the same genetic information but differential gene expression provides well-defined cellular specializations. However, the microbialites raise the question of how much complexity and structure can be achieved by a high degree of communication within a multitude of microbial cells. Our findings indicate a complex and interacting microbial consortium associated with the structures at Pavilion Lake, and revealed biomarkers for proteobacteria, sulphur reducing bacteria, and firmicutes (possibly photosynthetic heliobacteria), among others. Types of genetic exchange among these microbial cells may include lateral gene transfer via conjugation, transformation, and transduction, or other mechanisms. This finding may have significant implications for the evolution of life on Earth and possible life on other planets. References: Laval, B., Cady, S.L., Pollack, J.C., McKay, C.P., Bird, J.S., Grotzinger, J.P., Ford, D.C., and Bohm, H.R. (2000) Modern freshwater microbialite analogues for ancient dendritic reef structures. Nature 407, 626-629.

Geothermal prospection in the Greater Geneva Basin (Switzerland and France). Impact of diagenesis on reservoir properties of the Upper Jurassic carbonate sediments

NASA Astrophysics Data System (ADS)

Makhloufi, Yasin; Rusillon, Elme; Brentini, Maud; Clerc, Nicolas; Meyer, Michel; Samankassou, Elias

2017-04-01

Diagenesis of carbonate rocks is known to affect the petrophysical properties (porosity, permeability) of the host rock. Assessing the diagenetic history of the rock is thus essential when evaluating any reservoir exploitation project. The Canton of Geneva (Switzerland) is currently exploring the opportunities for geothermal energy exploitation in the Great Geneva Basin (GGB) sub-surface. In this context, a structural analysis of the basin (Clerc et al., 2016) associated with reservoir appraisal (Brentini et al., 2017) and rock-typing of reservoir bodies of potential interest were conducted (Rusillon et al., 2017). Other geothermal exploitation projects elsewhere (e.g. Bavaria, south Germany, Paris Basin, France) showed that dolomitized carbonate rocks have good reservoir properties and are suitable for geothermal energy production. The objectives of this work are to (1) describe and characterize the dolomitized bodies in the GGB and especially their diagenetic history and (2) quantify the reservoir properties of those bodies (porosity, permeability). Currently, our study focuses on the Upper Jurassic sedimentary bodies of the GGB. Field and well data show that the dolomitization is not ubiquitous in the GGB. Results from the petrographical analyses of the Kimmeridgian cores (Humilly-2) and of field analogues (Jura, Saleve and Vuache mountains) display complex diagenetic histories, dependent of the study sites. The paragenesis exhibits several stages of interparticular calcite cementation as well as different stages of dolomitization and/or dedolomitization. Those processes seem to follow constrained path of fluid migrations through burial, faulting or exhumation during the basin's history. These complex diagenetic histories affected the petrophysical and microstructural properties via porogenesis (conservation of initial porosity, moldic porosity) and/or poronecrosis events. The best reservoir properties appear to be recorded in patch reef and peri-reefal depositional environments in association with porous dolomitized intervals (Rusilloon et al., 2017). The work presented here will help to constrain and quantify reservoir heterogeneities in a complex reservoir and to provide insights into porosity and permeability distribution that will ultimately help in reservoir modeling, a crucial step for further possible exploitation. Brentini et al. 2017: Geothermal prospection in the Greater Geneva Basin: integration of geological data in the new Information System. Abstract, EGU General Assembly 2017, Vienna, Austria. Clerc et al. 2016: Structural Modeling of the Geneva Basin for Geothermal Ressource Assessment. Abstract, 14th Swiss Geoscience Meeting, Geneva, Switzerland. Rusillon et al., 2017: Geothermal prospection in the Greater Geneva Basin (Switzerland and France): structural and reservoir quality assessment. Abstract, EGU General Assembly 2017, Vienna, Austria.

Advances and unresolved challenges in the structural characterization of isomeric lipids.

PubMed

Hancock, Sarah E; Poad, Berwyck L J; Batarseh, Amani; Abbott, Sarah K; Mitchell, Todd W

2017-05-01

As the field of lipidomics grows and its application becomes wide and varied it is important that we don't forget its foundation, i.e. the identification and measurement of molecular lipids. Advances in liquid chromatography and the emergence of ion mobility as a useful tool in lipid analysis are allowing greater separation of lipid isomers than ever before. At the same time, novel ion activation techniques, such as ozone-induced dissociation, are pushing lipid structural characterization by mass spectrometry to new levels. Nevertheless, the quantitative capacity of these techniques is yet to be proven and further refinements are required to unravel the high level of lipid complexity found in biological samples. At present there is no one technique capable of providing full structural characterization of lipids from a biological sample. There are however, numerous techniques now available (as discussed in this review) that could be deployed in a targeted approach. Moving forward, the combination of advanced separation and ion activation techniques is likely to provide mass spectrometry-based lipidomics with its best opportunity to achieve complete molecular-level lipid characterization and measurement from complex mixtures. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

Relationships between Algae, Benthic Herbivorous Invertebrates and Fishes in Rocky Sublittoral Communities of a Temperate Sea (Mediterranean)

NASA Astrophysics Data System (ADS)

Ruitton, S.; Francour, P.; Boudouresque, C. F.

2000-02-01

In situ surveys were used to examine the contribution of benthic herbivorous invertebrates and fishes to the organization of Mediterranean rocky sublittoral communities. Shallow (1-3 m) and deep (6-8 m) sampling sites, in natural areas and on man-made structures, were characterized by a structural complexity index (cavity index and mean size of cavity aperture), algal cover (encrusting, turfy, shrubby and arborescent algae) and the density of benthic herbivorous invertebrates and fish. A relationship between structural complexity and biota was only evident for some fish species ( Diplodus spp. and Sarpa salpa) at deep sites, where they not only feed but also shelter. Three benthic herbivorous invertebrates, the sea urchins Paracentrotus lividus and Arbacia lixula, and the limpet Patella caerulea , are associated with communities dominated by encrusting algae. Variations in their abundance and role in structuring algal communities follow a depth gradient: P. caerulea and A. lixula are mainly present at shallow sites and P. lividus at deep sites. These benthic herbivorous invertebrates may account for the structure of shallow algal communities. In contrast, at deep sites, fishes (the omnivorous Diplodus spp. and the herbivorous S. salpa) have a potential importance in controlling sublittoral algae, in addition to invertebrates. It is suggested that the ecological impact of herbivorous and omnivorous fishes in temperate seas could be greater than is generally thought. Experiments should be designed to validate this postulate.

Gravity investigations of the Chesapeake Bay impact structure

USGS Publications Warehouse

Plescia, J.B.; Daniels, D.L.; Shah, A.K.

2009-01-01

The Chesapeake Bay impact structure is a complex impact crater, ??85 km in diameter, buried beneath postimpact sediments. Its main structural elements include a central uplift of crystalline bedrock, a surrounding inner crater filled with impact debris, and an annular faulted margin composed of block-faulted sediments. The gravity anomaly is consistent with that of a complex impact consisting of a central positive anomaly over the central uplift and an annular negative anomaly over the inner crater. An anomaly is not recognized as being associated with the faulted margin or the outer edge of the structure. Densities from the Eyreville drill core and modeling indicate a density contrast of ??0.3-0.6 g cm-3 between crystalline basement and the material that fills the inner crater (e.g., Exmore breccia and suevite). This density contrast is somewhat higher than for other impact structures, but it is a function of the manner in which the crater fill was deposited (as a marine resurge deposit). Modeling of the gravity data is consistent with a depth to basement of ??1600 m at the site of Eyreville drill hole and 800 m at the central uplift. Both depths are greater than the depth at which crystalline rocks were encountered in the cores, suggesting that the cored material is highly fractured para-allochthonous rock. ?? 2009 The Geological Society of America.

The influence of a reverse-reactivated normal fault on natural fracture geometries and relative chronologies at Castle Cove, Otway Basin

NASA Astrophysics Data System (ADS)

Debenham, Natalie; King, Rosalind C.; Holford, Simon P.

2018-07-01

Despite the ubiquity of normal faults that have undergone compressional inversion, documentation of the structural history of natural fractures around these structures is limited. In this paper, we investigate the geometries and relative chronologies of natural fractures adjacent to a reverse-reactivated normal fault, the Castle Cove Fault in the Otway Basin, southeast Australia. Local variations in strain resulted in greater deformation within the fault damage zone closer to the fault. Structural mapping within the damage zone reveals a complex tectonic history recording both regional and local perturbations in stress and a total of 11 fracture sets were identified, with three sets geometrically related to the Castle Cove Fault. The remaining fracture sets formed in response to local stresses at Castle Cove. Rifting in the late Cretaceous resulted in normal movement of the Castle Cove Fault and associated rollover folding, and the formation of the largest fracture set. Reverse-reactivation of the fault and associated anticlinal folding occurred during late Miocene to Pliocene compression. Rollover folding may have provided structural traps if seals were not breached by fractures, however anticlinal folding likely post-dated the main episodes of hydrocarbon generation and migration in the region. This study highlights the need to conduct careful reconstruction of the structural histories of fault zones that experienced complex reactivation histories when attempting to define off-fault fluid flow properties.

Regulation of glycan structures in murine embryonic stem cells: combined transcript profiling of glycan-related genes and glycan structural analysis.

PubMed

Nairn, Alison V; Aoki, Kazuhiro; dela Rosa, Mitche; Porterfield, Mindy; Lim, Jae-Min; Kulik, Michael; Pierce, J Michael; Wells, Lance; Dalton, Stephen; Tiemeyer, Michael; Moremen, Kelley W

2012-11-02

The abundance and structural diversity of glycans on glycoproteins and glycolipids are highly regulated and play important roles during vertebrate development. Because of the challenges associated with studying glycan regulation in vertebrate embryos, we have chosen to study mouse embryonic stem (ES) cells as they differentiate into embryoid bodies (EBs) or into extraembryonic endodermal (ExE) cells as a model for cellular differentiation. We profiled N- and O-glycan structures isolated from these cell populations and examined transcripts encoding the corresponding enzymatic machinery for glycan biosynthesis in an effort to probe the mechanisms that drive the regulation of glycan diversity. During differentiation from mouse ES cells to either EBs or ExE cells, general trends were detected. The predominance of high mannose N-glycans in ES cells shifted to an equal abundance of complex and high mannose structures, increased sialylation, and increased α-Gal termination in the differentiated cell populations. Whereas core 1 O-glycan structures predominated in all three cell populations, increased sialylation and increased core diversity characterized the O-glycans of both differentiated cell types. Increased polysialylation was also found in both differentiated cell types. Differences between the two differentiated cell types included greater sialylation of N-glycans in EBs, whereas α-Gal-capped structures were more prevalent in ExE cells. Changes in glycan structures generally, but not uniformly, correlated with alterations in transcript abundance for the corresponding biosynthetic enzymes, suggesting that transcriptional regulation contributes significantly to the regulation of glycan expression. Knowledge of glycan structural diversity and transcript regulation should provide greater understanding of the roles of protein glycosylation in vertebrate development.

Emotional Complexity and Emotional Well-being in Older Adults: Risks of High Neuroticism

PubMed Central

Ready, Rebecca E.; Åkerstedt, Anna M.; Mroczek, Daniel K.

2011-01-01

Older and midlife adults tend to report greater emotional complexity and greater emotional wellbeing than younger adults but there is variability in these factors across the lifespan. The current study determined how the personality trait of Neuroticism at baseline predicts emotional complexity and emotional well-being 10 years later; a goal was to determine if Neuroticism is a stronger predictor of these emotion outcomes with increasing age in adulthood. Data were from two waves of the MIDUS projects (N = 1,503; aged 34 to 84). Greater Neuroticism predicted less emotional complexity as indicated by associations between Positive (PA) and Negative Affect (NA), particularly for older participants. Neuroticism predicted lower emotional well-being and this association was stronger for older and midlife than for younger adults. Overall, high Neuroticism may be greater liability for poor emotion outcomes for older and perhaps for midlife adults than for younger persons. Clinical and theoretical implications of this conclusion are discussed. PMID:21854349

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cody, V.; Pace, J.; Rosowsky, A.

It has been shown that 2,4-diamino-6-arylmethylpteridines and 2,4-diamino-5-arylmethylpyrimidines containing an O-carboxylalkyloxy group in the aryl moiety are potent and selective inhibitors of the dihydrofolate reductase (DHFR) from opportunistic pathogens such as Pneumocystis carinii, the causative agent of Pneumocystis pneumonia in HIV/AIDS patients. In order to understand the structure-activity profile observed for a series of substituted dibenz[b,f]azepine antifolates, the crystal structures of mouse DHFR (mDHFR; a mammalian homologue) holo and ternary complexes with NADPH and the inhibitor 2,4-diamino-6-(2{prime}-hydroxydibenz[b,f]azepin-5-yl)methylpteridine were determined to 1.9 and 1.4 A resolution, respectively. Structural data for the ternary complex with the potent O-(3-carboxypropyl) inhibitor PT684 revealed nomore » electron density for the O-carboxylalkyloxy side chain. The side chain was either cleaved or completely disordered. The electron density fitted the less potent hydroxyl compound PT684a. Additionally, cocrystallization of mDHFR with NADPH and the less potent 2{prime}-(4-carboxybenzyl) inhibitor PT682 showed no electron density for the inhibitor and resulted in the first report of a holoenzyme complex despite several attempts at crystallization of a ternary complex. Modeling data of PT682 in the active site of mDHFR and P. carinii DHFR (pcDHFR) indicate that binding would require ligand-induced conformational changes to the enzyme for the inhibitor to fit into the active site or that the inhibitor side chain would have to adopt an alternative binding mode to that observed for other carboxyalkyloxy inhibitors. These data also show that the mDHFR complexes have a decreased active-site volume as reflected in the relative shift of helix C (residues 59-64) by 0.6 A compared with pcDHFR ternary complexes. These data are consistent with the greater inhibitory potency against pcDHFR.« less

The Crystal Structure of Coxsackievirus A21 and Its Interaction with ICAM-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Chuan; Bator-Kelly, Carol M.; Rieder, Elizabeth

2010-11-30

CVA21 and polioviruses both belong to the Enterovirus genus in the family of Picornaviridae, whereas rhinoviruses form a distinct picornavirus genus. Nevertheless, CVA21 and the major group of human rhinoviruses recognize intercellular adhesion molecule-1 (ICAM-1) as their cellular receptor, whereas polioviruses use poliovirus receptor. The crystal structure of CVA21 has been determined to 3.2 {angstrom} resolution. Its structure has greater similarity to poliovirus structures than to other known picornavirus structures. Cryo-electron microscopy (cryo-EM) was used to determine an 8.0 {angstrom} resolution structure of CVA21 complexed with an ICAM-1 variant, ICAM-1{sup Kilifi}. The cryo-EM map was fitted with the crystal structuresmore » of ICAM-1 and CVA21. Significant differences in the structure of CVA21 with respect to the poliovirus structures account for the inability of ICAM-1 to bind polioviruses. The interface between CVA21 and ICAM-1 has shape and electrostatic complementarity with many residues being conserved among those CVAs that bind ICAM-1.« less

Low temperature X-ray structure analyses combined with NBO studies of a new heteroleptic octa-coordinated Holmium(III) complex with N,N,N-tridentate hydrazono-phthalazine-type ligand

NASA Astrophysics Data System (ADS)

Soliman, Saied M.; El-Faham, Ayman

2018-04-01

The new heteroleptic [HoL(H2O)5]Br3 complex, L is hydrazono-phthalazine ligand, is synthesized and its molecular structure aspects were analyzed using single crystal X-ray structure (SCXRD), Hirshfeld (HF) analysis, quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) method. The SCXRD showed that the Ho is octa-coordinated with one N,N,N-tridentate ligand L and five water molecules. The HF analysis is used to analyze the molecular packing in the [HoL(H2O)5]Br3crystal structure. The complex cations are connected via strong Osbnd H⋯Br and Nsbnd H⋯Br H-bonding interactions which have greater importance than the Csbnd H⋯Br contacts. Also, all the Hosbnd N and Hosbnd O bonds have the characteristics of closed shell interactions using QTAIM. The natural orbitals included in these interactions were analyzed using NBO method. The alpha LP*(8)Ho and beta LP*(4)Ho which have mainly s-orbital characters are the most important anti-bonding natural orbitals included in all Ho-N and Hosbnd O bonds. The rest of the Ho anti-bonding orbitals which have either p or d-orbital characters shared partially in the Ho-ligands interactions. Natural charges analysis revealed the presence of significant amount of electron density (0.9225-0.9300 e) transferred from the ligands to Ho (2.0700-2.0775 e). Spherical spin density with ∼4.0 e is predicted over the Ho atom.

The forgotten grammatical category: Adjective use in agrammatic aphasia

PubMed Central

Meltzer-Asscher, Aya; Thompson, Cynthia K.

2014-01-01

Background In contrast to nouns and verbs, the use of adjectives in agrammatic aphasia has not been systematically studied. However, because of the linguistic and psycholinguistic attributes of adjectives, some of which overlap with nouns and some with verbs, analysis of adjective production is important for testing theories of word class production deficits in agrammatism. Aims The objective of the current study was to compare adjective use in agrammatic and healthy individuals, focusing on three factors: overall adjective production rate, production of predicative and attributive adjectives, and production of adjectives with complex argument structure. Method & Procedures Narratives elicited from 14 agrammatic and 14 control participants were coded for open class grammatical category production (i.e., nouns, verbs, adjectives), with each adjective also coded for its syntactic environment (attributive/predicative) and argument structure. Outcomes & Results Overall, agrammatic speakers used adjectives in proportions similar to that of cognitively healthy speakers. However, they exhibited a greater proportion of predicative adjectives and a lesser proportion of attributive adjectives, compared to controls. Additionally, agrammatic participants produced adjectives with less complex argument structure than controls. Conclusions The overall normal-like frequency of adjectives produced by agrammatic speakers suggests that agrammatism does not involve an inherent difficulty with adjectives as a word class or with predication, or that it entails a deficit in processing low imageability words. However, agrammatic individuals’ reduced production of attributive adjectives and adjectives with complements extends previous findings of an adjunction deficit and of impairment in complex argument structure processing, respectively, to the adjectival domain. The results suggest that these deficits are not tied to a specific grammatical category. PMID:24882945

The forgotten grammatical category: Adjective use in agrammatic aphasia.

PubMed

Meltzer-Asscher, Aya; Thompson, Cynthia K

2014-07-01

In contrast to nouns and verbs, the use of adjectives in agrammatic aphasia has not been systematically studied. However, because of the linguistic and psycholinguistic attributes of adjectives, some of which overlap with nouns and some with verbs, analysis of adjective production is important for testing theories of word class production deficits in agrammatism. The objective of the current study was to compare adjective use in agrammatic and healthy individuals, focusing on three factors: overall adjective production rate, production of predicative and attributive adjectives, and production of adjectives with complex argument structure. Narratives elicited from 14 agrammatic and 14 control participants were coded for open class grammatical category production (i.e., nouns, verbs, adjectives), with each adjective also coded for its syntactic environment (attributive/predicative) and argument structure. Overall, agrammatic speakers used adjectives in proportions similar to that of cognitively healthy speakers. However, they exhibited a greater proportion of predicative adjectives and a lesser proportion of attributive adjectives, compared to controls. Additionally, agrammatic participants produced adjectives with less complex argument structure than controls. The overall normal-like frequency of adjectives produced by agrammatic speakers suggests that agrammatism does not involve an inherent difficulty with adjectives as a word class or with predication, or that it entails a deficit in processing low imageability words. However, agrammatic individuals' reduced production of attributive adjectives and adjectives with complements extends previous findings of an adjunction deficit and of impairment in complex argument structure processing, respectively, to the adjectival domain. The results suggest that these deficits are not tied to a specific grammatical category.

Csbnd H⋯Ni and Csbnd H⋯π(chelate) interactions in nickel(II) complexes involving functionalized dithiocarbamates and triphenylphosphine

NASA Astrophysics Data System (ADS)

Sathiyaraj, E.; Thirumaran, S.; Selvanayagam, S.; Sridhar, B.; Ciattini, Samuele

2018-05-01

New bis(N-benzyl-N-substituted benzyldithiocarbamato-S,S‧)nickel(II) (1-3) and (N-benzyl-N-substituted benzyldithiocarbamato-S,S‧)(isothiocyanato-N)- (triphenylphosphane)nickel(II) (4-6) [where substituted benzyl = 2-HOsbnd C6H4sbnd CH2sbnd (1,4), 3-HOsbnd C6H4sbnd CH2sbnd (2,5), 4-Fsbnd C6H4sbnd CH2sbnd (3,6)] were synthesized and characterized using IR, electronic, and NMR (1H and 13C) spectra. X-ray structural analysis of homoleptic complex (1) and heteroleptic complexes (5 and 6) confirmed the presence of four coordinated nickel in a distorted square planar arrangement with NiS4 and NiS2PN chromophores, respectively. The νC-S stretching vibrations are observed around 990 cm-1 without any splitting supporting the bidentate coordination of the dithiocarbamate ligand. Electronic spectral studies of all the complexes (1-6) indicate that the geometry of the nickel atom is probably square planar. NMR spectra of all homoleptic and heteroleptic complexes (1-6) reveal a weak signal associated with the backbone carbon (N13CS2) in the region 204.0-210.0 ppm with a weak intensity characteristic of the quaternary carbon signals. The greater trans influence of triphenylphosphine in complexes 5 and 6 is supported by the long Nisbnd S distance compared to other Nisbnd S distance which is opposite to the NCS- ligand. In the structure of complex 5, C-H⋯π(chelate) interactions results in polymeric chain. Both structures show intramolecular Ni⋯H interactions but that on 6 is the strongest. C-H⋯π interactions are also found in 1, 5 and 6. Hirshfeld surface analysis and the associated 2D fingerprint plots of 1, 5 and 6 have been studied to evaluate intermolecular interactions. The molecular geometries of complexes 1, 5 and 6 have been optimized by abinitio HF method using LANL2DZ program.

Challenging the paradigms of deep-sea ecology.

PubMed

Danovaro, Roberto; Snelgrove, Paul V R; Tyler, Paul

2014-08-01

Deep-sea ecosystems represent Earth's major ecological research frontier. Focusing on seafloor ecosystems, we demonstrate how new technologies underpin discoveries that challenge major ecological hypotheses and paradigms, illuminating new deep-sea geosphere-biosphere interactions. We now recognize greater habitat complexity, new ecological interactions and the importance of 'dark energy', and chemosynthetic production in fuelling biodiversity. We also acknowledge functional hotspots that contradict a food-poor, metabolically inactive, and minor component of global carbon cycles. Symbioses appear widespread, revealing novel adaptations. Populations show complex spatial structure and evolutionary histories. These new findings redefine deep-sea ecology and the role of Earth's largest biome in global biosphere functioning. Indeed, deep-sea exploration can open new perspectives in ecological research to help mitigate exploitation impacts. Copyright © 2014 Elsevier Ltd. All rights reserved.

Structural and Functional Studies of H. seropedicae RecA Protein – Insights into the Polymerization of RecA Protein as Nucleoprotein Filament

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leite, Wellington C.; Galvão, Carolina W.; Saab, Sérgio C.

The bacterial RecA protein plays a role in the complex system of DNA damage repair. Here, we report the functional and structural characterization of the Herbaspirillum seropedicae RecA protein (HsRecA). HsRecA protein is more efficient at displacing SSB protein from ssDNA than Escherichia coli RecA protein. HsRecA also promotes DNA strand exchange more efficiently. The three dimensional structure of HsRecA-ADP/ATP complex has been solved to 1.7 Å resolution. HsRecA protein contains a small N-terminal domain, a central core ATPase domain and a large C-terminal domain, that are similar to homologous bacterial RecA proteins. Comparative structural analysis showed that the N-terminalmore » polymerization motif of archaeal and eukaryotic RecA family proteins are also present in bacterial RecAs. Reconstruction of electrostatic potential from the hexameric structure of HsRecA-ADP/ATP revealed a high positive charge along the inner side, where ssDNA is bound inside the filament. The properties of this surface may explain the greater capacity of HsRecA protein to bind ssDNA, forming a contiguous nucleoprotein filament, displace SSB and promote DNA exchange relative to EcRecA. In conclusion, our functional and structural analyses provide insight into the molecular mechanisms of polymerization of bacterial RecA as a helical nucleoprotein filament.« less

Structural and Functional Studies of H. seropedicae RecA Protein – Insights into the Polymerization of RecA Protein as Nucleoprotein Filament

PubMed Central

Galvão, Carolina W.; Saab, Sérgio C.; Iulek, Jorge; Etto, Rafael M.; Steffens, Maria B. R.; Chitteni-Pattu, Sindhu; Stanage, Tyler; Keck, James L.; Cox, Michael M.

2016-01-01

The bacterial RecA protein plays a role in the complex system of DNA damage repair. Here, we report the functional and structural characterization of the Herbaspirillum seropedicae RecA protein (HsRecA). HsRecA protein is more efficient at displacing SSB protein from ssDNA than Escherichia coli RecA protein. HsRecA also promotes DNA strand exchange more efficiently. The three dimensional structure of HsRecA-ADP/ATP complex has been solved to 1.7 Å resolution. HsRecA protein contains a small N-terminal domain, a central core ATPase domain and a large C-terminal domain, that are similar to homologous bacterial RecA proteins. Comparative structural analysis showed that the N-terminal polymerization motif of archaeal and eukaryotic RecA family proteins are also present in bacterial RecAs. Reconstruction of electrostatic potential from the hexameric structure of HsRecA-ADP/ATP revealed a high positive charge along the inner side, where ssDNA is bound inside the filament. The properties of this surface may explain the greater capacity of HsRecA protein to bind ssDNA, forming a contiguous nucleoprotein filament, displace SSB and promote DNA exchange relative to EcRecA. Our functional and structural analyses provide insight into the molecular mechanisms of polymerization of bacterial RecA as a helical nucleoprotein filament. PMID:27447485

Family Relationships and Well-Being

PubMed Central

Thomas, Patricia A; Liu, Hui; Umberson, Debra

2017-01-01

Abstract Family relationships are enduring and consequential for well-being across the life course. We discuss several types of family relationships—marital, intergenerational, and sibling ties—that have an important influence on well-being. We highlight the quality of family relationships as well as diversity of family relationships in explaining their impact on well-being across the adult life course. We discuss directions for future research, such as better understanding the complexities of these relationships with greater attention to diverse family structures, unexpected benefits of relationship strain, and unique intersections of social statuses. PMID:29795792

Multiplex social ecological network analysis reveals how social changes affect community robustness more than resource depletion.

PubMed

Baggio, Jacopo A; BurnSilver, Shauna B; Arenas, Alex; Magdanz, James S; Kofinas, Gary P; De Domenico, Manlio

2016-11-29

Network analysis provides a powerful tool to analyze complex influences of social and ecological structures on community and household dynamics. Most network studies of social-ecological systems use simple, undirected, unweighted networks. We analyze multiplex, directed, and weighted networks of subsistence food flows collected in three small indigenous communities in Arctic Alaska potentially facing substantial economic and ecological changes. Our analysis of plausible future scenarios suggests that changes to social relations and key households have greater effects on community robustness than changes to specific wild food resources.

The structure and stability of aqueous rare-earth elements in hydrothermal fluids: New results on neodymium(III) aqua and chloroaqua complexes in aqueous solutions to 500 °C and 520 MPa

USGS Publications Warehouse

Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

2009-01-01

X-ray absorption spectroscopy (XAS) measurements were made at the Nd L3-edge on neodymium(III) aqua and chloroaqua complexes in low pH aqueous solutions from 25 to 500????C and up to 520??MPa. Analysis of the extended X-ray absorption fine structure of the XAS spectra measured from a 0.07??m Nd/0.16??m HNO3 aqueous solution reveals a contraction of the Nd-O distance of the Nd3+ aqua ion at a uniform rate of ~ 0.013????/100????C and a uniform reduction of the number of coordinated H2O molecules from 10.0 ?? 0.9 to 7.4 ?? 0.9 over the range from 25 to 500????C and up to 370??MPa. The rate of reduction of the first-shell water molecules with temperature for Nd3+ (26%) is intermediate between the rate for the Gd3+ aqua ion (22% from 25 to 500????C) and the rates for the Eu3+ (29% from 25 to 400????C) and the Yb3+ aqua ions (42% from 25 to 500????C) indicating an intermediate stability of the Nd3+ aqua ion consistent with the tetrad effect. Nd L3-edge XAS measurements of 0.05??m NdCl3 aqueous solution at 25 to 500????C and up to 520??MPa show that stepwise inner-sphere complexes most likely of the type Nd(H2O)?? - nCln+3 - n occur in the solution at elevated temperatures, where ?? ??? 9 at 150????C decreasing to ~ 6 at 500????C and the number of chloride ions (n) of the chloroaqua complexes increases uniformly with temperature from 1.2 ?? 0.2 to 2.0 ?? 0.2 in the solution upon increase of temperature from 150 to 500????C. Conversely, the number of H2O ligands of Nd(H2O)?? - nCln+3 - n complexes is uniformly reduced with temperature from 7.5 ?? 0.8 to 3.7 ?? 0.3 in the aqueous solution, in the same temperature range. These data show greater stability of neodymium(III) than gadolinium(III) and ytterbium(III) chloride complexes in low pH aqueous solutions at elevated temperatures. Our data suggest a greater stability of aqueous light REE than that of heavy REE chloride complexes in low pH fluids at elevated temperatures consistent with REE analysis of fluids from deep-sea hydrothermal vents. ?? 2008 Elsevier B.V.

Folate-conjugated boron nitride nanospheres for targeted delivery of anticancer drugs

PubMed Central

Feng, Shini; Zhang, Huijie; Yan, Ting; Huang, Dandi; Zhi, Chunyi; Nakanishi, Hideki; Gao, Xiao-Dong

2016-01-01

With its unique physical and chemical properties and structural similarity to carbon, boron nitride (BN) has attracted considerable attention and found many applications. Biomedical applications of BN have recently started to emerge, raising great hopes in drug and gene delivery. Here, we developed a targeted anticancer drug delivery system based on folate-conjugated BN nanospheres (BNNS) with receptor-mediated targeting. Folic acid (FA) was successfully grafted onto BNNS via esterification reaction. In vitro cytotoxicity assay showed that BNNS-FA complexes were non-toxic to HeLa cells up to a concentration of 100 μg/mL. Then, doxorubicin hydrochloride (DOX), a commonly used anticancer drug, was loaded onto BNNS-FA complexes. BNNS-FA/DOX complexes were stable at pH 7.4 but effectively released DOX at pH 5.0, which exhibited a pH sensitive and sustained release pattern. BNNS-FA/DOX complexes could be recognized and specifically internalized by HeLa cells via FA receptor-mediated endocytosis. BNNS-FA/DOX complexes exhibited greater cytotoxicity to HeLa cells than free DOX and BNNS/DOX complexes due to the increased cellular uptake of DOX mediated by the FA receptor. Therefore, BNNS-FA complexes had strong potential for targeted cancer therapy. PMID:27695318

Response of walleye and yellow perch to water-level fluctuations in glacial lakes

USGS Publications Warehouse

Dembkowski, D.J.; Chipps, Steven R.; Blackwell, B. G.

2014-01-01

The influence of water levels on population characteristics of yellow perch, Perca flavescens (Mitchill), and walleye, Sander vitreus (Mitchill), was evaluated across a range of glacial lakes in north-eastern South Dakota, USA. Results showed that natural variation in water levels had an important influence on frequently measured fish population characteristics. Yellow perch abundance was significantly (P<0.10) greater during elevated water levels. Yellow perch size structure, as indexed by the proportional size distribution of quality- and preferred-length fish (PSD and PSD-P), was significantly greater during low-water years, as was walleye PSD. Mean relative weight of walleye increased significantly during high-water periods. The dynamic and unpredictable nature of water-level fluctuations in glacial lakes ultimately adds complexity to management of these systems.

Synthesis, thermal analyses, characterization and biological evaluation of new enrofloxacin vanadium(V) solvates(L) (L = An, DMF, Py, Et3N and o-Tol)

NASA Astrophysics Data System (ADS)

Zordok, Wael A.; Sadeek, Sadeek A.

2016-09-01

Five metal complexes of antibacterial agent enrofloxacin with vanadium(V) in the presence of aniline, pyridine, orthotolidine and triethylamine as nitrogen donor molecules and dimethylformamide as oxygen donor molecule have been prepared and characterized with physicochemical and diverse spectroscopic techniques (IR, UV-Vis. and 1H NMR spectroscopes) as well as thermal analysis. The deprotonated enrofloxacin complexes of V(V) were isolated as solids with the general formulas; [VO(Enr)2DMF]Cl·5H2O, [VO(Enr)2An]Cl·2H2O, [VO(Enr)2o-Tol]Cl·H2O, [VO(Enr)2Py]Cl·4H2O and [VO(Enr)2Et3N]Cl·6H2O. The prepared complexes are formed with a metal to ligand ratios as 1:2:1 for all complexes. The lowest energy model structure of each complex has been proposed by using the density functional theory (DFT) at the B3LYP/CEP-31G level of theory. The energy barrier for the pyridine complex greater than others complexes while, Et3N complex has lower value. The ligand and their metal complexes were also evaluated for their antibacterial activity against three Gram (+ve) and three Gram (-ve) microorganisms.

Dynamic generation of a table of contents with consumer-friendly labels.

PubMed

Miller, Trudi; Leroy, Gondy; Wood, Elizabeth

2006-01-01

Consumers increasingly look to the Internet for health information, but available resources are too difficult for the majority to understand. Interactive tables of contents (TOC) can help consumers access health information by providing an easy to understand structure. Using natural language processing and the Unified Medical Language System (UMLS), we have automatically generated TOCs for consumer health information. The TOC are categorized according to consumer-friendly labels for the UMLS semantic types and semantic groups. Categorizing phrases by semantic types is significantly more correct and relevant. Greater correctness and relevance was achieved with documents that are difficult to read than those at an easier reading level. Pruning TOCs to use categories that consumers favor further increases relevancy and correctness while reducing structural complexity.

iss009e23808

NASA Image and Video Library

2004-09-20

ISS009-E-23808 (20 September 2004) --- A fringing coral reef in the Red Sea is featured in this image photographed by an Expedition 9 crewmember on the International Space Station (ISS). The Sudanese coast of the Red Sea is a well known destination for divers due to clear water and abundance of coral reefs (or “shia’ab” in Arabic). According to NASA scientists studying the ISS imagery, reefs are formed primarily from precipitation of calcium carbonate by corals; massive reef structures are built over thousands of years of succeeding generations of coral. In the Red Sea, fringing reefs form on shallow shelves of less than 50 meters depth along the coastline. This photograph illustrates the intricate morphology of the reef system located along the coast between Port Sudan to the northwest and the Tokar River delta to the southeast. Close to shore, fringing reefs border the coastline. Farther offshore grows a larger, more complicated barrier reef structure. Different parts of the reef structure show up as variable shades of light blue. Deeper water channels (darker blue) define the boundaries for individual reefs within the greater barrier reef system. Such a complex pattern of reefs may translate into greater ecosystem diversity through a wide variety of local reef environments.

Thermostability promotes the cooperative function of split adenylate kinases.

PubMed

Nguyen, Peter Q; Liu, Shirley; Thompson, Jeremy C; Silberg, Jonathan J

2008-05-01

Proteins can often be cleaved to create inactive polypeptides that associate into functional complexes through non-covalent interactions, but little is known about what influences the cooperative function of the ensuing protein fragments. Here, we examine whether protein thermostability affects protein fragment complementation by characterizing the function of split adenylate kinases from the mesophile Bacillus subtilis (AKBs) and the hyperthermophile Thermotoga neapolitana (AKTn). Complementation studies revealed that the split AKTn supported the growth of Escherichia coli with a temperature-sensitive AK, but not the fragmented AKBs. However, weak complementation occurred when the AKBs fragments were fused to polypeptides that strongly associate, and this was enhanced by a Q16L mutation that thermostabilizes the full-length protein. To examine how the split AK homologs differ in structure and function, their catalytic activity, zinc content, and circular dichroism spectra were characterized. The reconstituted AKTn had higher levels of zinc, greater secondary structure, and >10(3)-fold more activity than the AKBs pair, albeit 17-fold less active than full-length AKTn. These findings provide evidence that the design of protein fragments that cooperatively function can be improved by choosing proteins with the greatest thermostability for bisection, and they suggest that this arises because hyperthermophilic protein fragments exhibit greater residual structure compared to their mesophilic counterparts.

Effect of Compositional Variation in TiO2-Based Flux-Cored Arc Welding Fluxes on the Thermo-physical Properties and Mechanical Behavior of a Weld Zone

NASA Astrophysics Data System (ADS)

Kim, J. B.; Lee, T. H.; Sohn, I.

2018-04-01

The effect of compositional variation in TiO2-based flux-cored arc welding fluxes on viscosity, wettability, and electronegativity was studied. The thermo-physical properties of the retrieved fluxes and their relationship with the mechanical properties of the weld zone, including tensile strength and micro-Vickers hardness, after welding were identified. Microstructural observation under similar welding conditions revealed significant grain coarsening at a corrected optical basicity (Λcorr) of 0.62, resulting in reduced strength and hardness due to greater heat transfer. Welding fluxes containing TiO2-based simple structural units should result in greater heat transfer due to the deficiency in complex [AlO4]5-- and [SiO4]4--based structural units, as identified through spectroscopic analyses using fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The electronegativity of the retrieved fluxes was also evaluated since higher electronegativity results in greater absorption of electrons in the arc, resulting in arc condensation towards the center direction. Consequently, deeper penetration could be obtained, where the highest electronegativity was identified to be approximately 0.62 of the corrected optical basicity. Thus, both the thermal conductivity and electronegativity of the welding fluxes were identified to determine the heat transfer phenomenon during flux-cored arc welding.

Effect of Compositional Variation in TiO2-Based Flux-Cored Arc Welding Fluxes on the Thermo-physical Properties and Mechanical Behavior of a Weld Zone

NASA Astrophysics Data System (ADS)

Kim, J. B.; Lee, T. H.; Sohn, I.

2018-07-01

The effect of compositional variation in TiO2-based flux-cored arc welding fluxes on viscosity, wettability, and electronegativity was studied. The thermo-physical properties of the retrieved fluxes and their relationship with the mechanical properties of the weld zone, including tensile strength and micro-Vickers hardness, after welding were identified. Microstructural observation under similar welding conditions revealed significant grain coarsening at a corrected optical basicity (Λcorr) of 0.62, resulting in reduced strength and hardness due to greater heat transfer. Welding fluxes containing TiO2-based simple structural units should result in greater heat transfer due to the deficiency in complex [AlO4]5-- and [SiO4]4--based structural units, as identified through spectroscopic analyses using fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The electronegativity of the retrieved fluxes was also evaluated since higher electronegativity results in greater absorption of electrons in the arc, resulting in arc condensation towards the center direction. Consequently, deeper penetration could be obtained, where the highest electronegativity was identified to be approximately 0.62 of the corrected optical basicity. Thus, both the thermal conductivity and electronegativity of the welding fluxes were identified to determine the heat transfer phenomenon during flux-cored arc welding.

Brain structure and verbal function across adulthood while controlling for cerebrovascular risks.

PubMed

Sanfratello, L; Lundy, S L; Qualls, C; Knoefel, J E; Adair, J C; Caprihan, A; Stephen, J M; Aine, C J

2017-04-08

The development and decline of brain structure and function throughout adulthood is a complex issue, with cognitive aging trajectories influenced by a host of factors including cerebrovascular risk. Neuroimaging studies of age-related cognitive decline typically reveal a linear decrease in gray matter (GM) volume/density in frontal regions across adulthood. However, white matter (WM) tracts mature later than GM, particularly in regions necessary for executive functions and memory. Therefore, it was predicted that a middle-aged group (MC: 35-45 years) would perform best on a verbal working memory task and reveal greater regional WM integrity, compared with both young (YC: 18-25 years) and elder groups (EC: 60+ years). Diffusion tensor imaging (DTI) and magnetoencephalography (MEG) were obtained from 80 healthy participants. Objective measures of cerebrovascular risk and cognition were also obtained. As predicted, MC revealed best verbal working memory accuracy overall indicating some maturation of brain function between YC and MC. However, contrary to the prediction fractional anisotropy values (FA), a measure of WM integrity, were not greater in MC (i.e., there were no significant differences in FA between YC and MC but both groups showed greater FA than EC). An overall multivariate model for MEG ROIs showed greater peak amplitudes for MC and YC, compared with EC. Subclinical cerebrovascular risk factors (systolic blood pressure and blood glucose) were negatively associated with FA in frontal callosal, limbic, and thalamic radiation regions which correlated with executive dysfunction and slower processing speed, suggesting their contribution to age-related cognitive decline. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Gemelli-obturator complex in the deep gluteal space: an anatomic and dynamic study.

PubMed

Balius, Ramon; Susín, Antonio; Morros, Carles; Pujol, Montse; Pérez-Cuenca, Dolores; Sala-Blanch, Xavier

2018-06-01

To investigate the behavior of the sciatic nerve during hip rotation at subgluteal space. Sonographic examination (high-resolution ultrasound machine at 5.0-14 MHZ) of the gemelli-obturator internus complex following two approaches: (1) a study on cadavers and (2) a study on healthy volunteers. The cadavers were examined in pronation, pelvis-fixed position by forcing internal and external rotations of the hip with the knee in 90° flexion. Healthy volunteers were examined during passive internal and external hip rotation (prone position; lumbar and pelvic regions fixed). Subjects with a history of major trauma, surgery or pathologies affecting the examined regions were excluded. The analysis included eight hemipelvis from six fresh cadavers and 31 healthy volunteers. The anatomical study revealed the presence of connective tissue attaching the sciatic nerve to the structures of the gemellus-obturator system at deep subgluteal space. The amplitude of the nerve curvature during rotating position was significantly greater than during resting position. During passive internal rotation, the sciatic nerve of both cadavers and healthy volunteers transformed from a straight structure to a curved structure tethered at two points as the tendon of the obturator internus contracted downwards. Conversely, external hip rotation caused the nerve to relax. Anatomically, the sciatic nerve is closely related to the gemelli-obturator internus complex. This relationship results in a reproducible dynamic behavior of the sciatic nerve during passive hip rotation, which may contribute to explain the pathological mechanisms of the obturator internal gemellus syndrome.

Visual Complexity and Affect: Ratings Reflect More Than Meets the Eye.

PubMed

Madan, Christopher R; Bayer, Janine; Gamer, Matthias; Lonsdorf, Tina B; Sommer, Tobias

2017-01-01

Pictorial stimuli can vary on many dimensions, several aspects of which are captured by the term 'visual complexity.' Visual complexity can be described as, "a picture of a few objects, colors, or structures would be less complex than a very colorful picture of many objects that is composed of several components." Prior studies have reported a relationship between affect and visual complexity, where complex pictures are rated as more pleasant and arousing. However, a relationship in the opposite direction, an effect of affect on visual complexity, is also possible; emotional arousal and valence are known to influence selective attention and visual processing. In a series of experiments, we found that ratings of visual complexity correlated with affective ratings, and independently also with computational measures of visual complexity. These computational measures did not correlate with affect, suggesting that complexity ratings are separately related to distinct factors. We investigated the relationship between affect and ratings of visual complexity, finding an 'arousal-complexity bias' to be a robust phenomenon. Moreover, we found this bias could be attenuated when explicitly indicated but did not correlate with inter-individual difference measures of affective processing, and was largely unrelated to cognitive and eyetracking measures. Taken together, the arousal-complexity bias seems to be caused by a relationship between arousal and visual processing as it has been described for the greater vividness of arousing pictures. The described arousal-complexity bias is also of relevance from an experimental perspective because visual complexity is often considered a variable to control for when using pictorial stimuli.

Visual Complexity and Affect: Ratings Reflect More Than Meets the Eye

PubMed Central

Madan, Christopher R.; Bayer, Janine; Gamer, Matthias; Lonsdorf, Tina B.; Sommer, Tobias

2018-01-01

Pictorial stimuli can vary on many dimensions, several aspects of which are captured by the term ‘visual complexity.’ Visual complexity can be described as, “a picture of a few objects, colors, or structures would be less complex than a very colorful picture of many objects that is composed of several components.” Prior studies have reported a relationship between affect and visual complexity, where complex pictures are rated as more pleasant and arousing. However, a relationship in the opposite direction, an effect of affect on visual complexity, is also possible; emotional arousal and valence are known to influence selective attention and visual processing. In a series of experiments, we found that ratings of visual complexity correlated with affective ratings, and independently also with computational measures of visual complexity. These computational measures did not correlate with affect, suggesting that complexity ratings are separately related to distinct factors. We investigated the relationship between affect and ratings of visual complexity, finding an ‘arousal-complexity bias’ to be a robust phenomenon. Moreover, we found this bias could be attenuated when explicitly indicated but did not correlate with inter-individual difference measures of affective processing, and was largely unrelated to cognitive and eyetracking measures. Taken together, the arousal-complexity bias seems to be caused by a relationship between arousal and visual processing as it has been described for the greater vividness of arousing pictures. The described arousal-complexity bias is also of relevance from an experimental perspective because visual complexity is often considered a variable to control for when using pictorial stimuli. PMID:29403412

A new complexity measure for time series analysis and classification

NASA Astrophysics Data System (ADS)

Nagaraj, Nithin; Balasubramanian, Karthi; Dey, Sutirth

2013-07-01

Complexity measures are used in a number of applications including extraction of information from data such as ecological time series, detection of non-random structure in biomedical signals, testing of random number generators, language recognition and authorship attribution etc. Different complexity measures proposed in the literature like Shannon entropy, Relative entropy, Lempel-Ziv, Kolmogrov and Algorithmic complexity are mostly ineffective in analyzing short sequences that are further corrupted with noise. To address this problem, we propose a new complexity measure ETC and define it as the "Effort To Compress" the input sequence by a lossless compression algorithm. Here, we employ the lossless compression algorithm known as Non-Sequential Recursive Pair Substitution (NSRPS) and define ETC as the number of iterations needed for NSRPS to transform the input sequence to a constant sequence. We demonstrate the utility of ETC in two applications. ETC is shown to have better correlation with Lyapunov exponent than Shannon entropy even with relatively short and noisy time series. The measure also has a greater rate of success in automatic identification and classification of short noisy sequences, compared to entropy and a popular measure based on Lempel-Ziv compression (implemented by Gzip).

Structural complexity, movement bias, and metapopulation extinction risk in dendritic ecological networks

USGS Publications Warehouse

Campbell Grant, Evan H.

2011-01-01

Spatial complexity in metacommunities can be separated into 3 main components: size (i.e., number of habitat patches), spatial arrangement of habitat patches (network topology), and diversity of habitat patch types. Much attention has been paid to lattice-type networks, such as patch-based metapopulations, but interest in understanding ecological networks of alternative geometries is building. Dendritic ecological networks (DENs) include some increasingly threatened ecological systems, such as caves and streams. The restrictive architecture of dendritic ecological networks might have overriding implications for species persistence. I used a modeling approach to investigate how number and spatial arrangement of habitat patches influence metapopulation extinction risk in 2 DENs of different size and topology. Metapopulation persistence was higher in larger networks, but this relationship was mediated by network topology and the dispersal pathways used to navigate the network. Larger networks, especially those with greater topological complexity, generally had lower extinction risk than smaller and less-complex networks, but dispersal bias and magnitude affected the shape of this relationship. Applying these general results to real systems will require empirical data on the movement behavior of organisms and will improve our understanding of the implications of network complexity on population and community patterns and processes.

Hydrogen bond assisted interaction of glutamine with chromium (III) complex of 8-hydroxyquinoline: Experimental and theoretical studies

NASA Astrophysics Data System (ADS)

Narayanan, Jayanthi; Carlos-Alberto, Aguilar H.; Arturo, Lazarini M.; Höpfl, Herbert; Enrique-Fernando, Velazquez C.; Fernando, Rocha A.; Fernando-Toyohiko, Wakida K.; Velazquez-Lopez, José E.; Lesli, Arroyo O.

2018-03-01

Chromium (III) complex [Cr (hq)3;C2H5OH] of 8-hydroxyquinoline (hq) was prepared and its structure was resolved by X-ray diffraction analysis at low-temperature, showing that Cr3+ ion presents in distorted octahedral geometry, and it is consistent with the DFT optimized structure. It was observed that solvent ethanol is involved a hydrogen bond with 8-hydroxyquinoline anion. Furthermore, the molecular orbital contributions to spectral bands observed for the complex were determined by TD-DFT. The interaction of [Cr (hq)3;C2H5OH] with glutamine (Gln) or asparagine (Asn) shows that the complex binds effectively with glutamine through hydrogen bonding (H2N+-HṡṡṡOethanol) to form a possible stable adduct [Cr (hq)3;C2H5OH)Gln], yielding its binding constant 10,000 times greater (1.4315 M-1) than that for Asn (5.0 × 10-4 M-1). This is apparently due to the formation of stable secondary coordination sphere through the hydrogen bond between the metal complex with Gln. This observation is good agreement with the total molecular energy as well as with the molecular orbital study, i.e. in the DFT calculation, a lower total molecular energy (-8299,549.441 kcal/mmol) for [Cr (hq)3;C2H5OH) Gln] was obtained than that resulted for [Cr (hq)3;C2H5OH)Asn] (-8194,799.867 kcal/mmol), establishing ethanol effectively stabilizes the interaction between glutamine and the complex. Finally, antibacterial properties of [Cr (hq)3;C2H5OH] against Gram positive Bacillus cereus and Gram negative Escherichia coli was also studied, and compared its bacterial growths for its adducts of glutamine or of asparagine.

Reaction landscape of a pentadentate N5-ligated Mn(II) complex with O2˙- and H2O2 includes conversion of a peroxomanganese(III) adduct to a bis(μ-oxo)dimanganese(III,IV) species.

PubMed

Leto, Domenick F; Chattopadhyay, Swarup; Day, Victor W; Jackson, Timothy A

2013-09-28

Herein we describe the chemical reactivity of the mononuclear [Mn(II)(N4py)(OTf)](OTf) (1) complex with hydrogen peroxide and superoxide. Treatment of 1 with one equivalent superoxide at -40 °C in MeCN formed the peroxomanganese(III) adduct, [Mn(III)(O2)(N4py)](+) (2) in ~30% yield. Complex 2 decayed over time and the formation of the bis(μ-oxo)dimanganese(III,IV) complex, [Mn(III)Mn(IV)(μ-O)2(N4py)2](3+) (3) was observed. When 2 was formed in higher yields (~60%) using excess superoxide, the [Mn(III)(O2)(N4py)](+) species thermally decayed to Mn(II) species and 3 was formed in no greater than 10% yield. Treatment of [Mn(III)(O2)(N4py)](+) with 1 resulted in the formation of 3 in ~90% yield, relative to the concentration of [Mn(III)(O2)(N4py)](+). This reaction mimics the observed chemistry of Mn-ribonucleotide reductase, as it features the conversion of two Mn(II) species to an oxo-bridged Mn(III)Mn(IV) compound using O2(-) as oxidant. Complex 3 was independently prepared through treatment of 1 with H2O2 and base at -40 °C. The geometric and electronic structures of 3 were probed using electronic absorption, electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), variable-temperature, variable-field MCD (VTVH-MCD), and X-ray absorption (XAS) spectroscopies. Complex 3 was structurally characterized by X-ray diffraction (XRD), which revealed the N4py ligand bound in an unusual tetradentate fashion.

3-D modeling of magnetotelluric data in the Paniri-Toconce volcanic chain, Central Andes.

NASA Astrophysics Data System (ADS)

Mancini, R.; Brasse, H.; Diaz, D.

2017-12-01

The research is located in the San Pedro-Toconce volcanic chain in the central volcanic zone of the Andes, North Chile. This area is interesting because of its proximity to several active volcanic centers, the geysers field of El Tatio and the recently opened geothermal plant Cerro Pabellon. Thermobarometry studies made in the area point to magma accumulated at 8 km below Lavas de Chao, and depths greater than 24 km below Toconce and Cerro de Leon. Regional geophysical studies show a distribution of conductive bodies around the complex, but the resolution of these studies at shallow depths are not conclusive. Data from wells show the possible presence of a large geothermal system in the southwest part of the complex, with depths of 2 km. Twenty broadband magnetotelluric (MT) stations were measured in the vicinity of the complex and combined with 15 long period MT stations measured in the 1990s, aiming at characterizing the deep conductive structures previously observed in the area, with magmatic bodies associated with the adjacent volcanic system. The results of a 3-D inversion show several conductive anomalies around the complex. Analyses of conductivity together with the 3-D models obtained indicate the presence of a geothermal system to the southwest of the complex with maximum depths of about 5 km, and two possible magmatic chambers below Paniri volcano and between Paniri and San Pedro volcanoes. In addition, the presence of a highly conductive structure to the east is obtained, associated with the Altiplano-Puna magma body (APMB).

Capturing complexity in work disability research: application of system dynamics modeling methodology.

PubMed

Jetha, Arif; Pransky, Glenn; Hettinger, Lawrence J

2016-01-01

Work disability (WD) is characterized by variable and occasionally undesirable outcomes. The underlying determinants of WD outcomes include patterns of dynamic relationships among health, personal, organizational and regulatory factors that have been challenging to characterize, and inadequately represented by contemporary WD models. System dynamics modeling (SDM) methodology applies a sociotechnical systems thinking lens to view WD systems as comprising a range of influential factors linked by feedback relationships. SDM can potentially overcome limitations in contemporary WD models by uncovering causal feedback relationships, and conceptualizing dynamic system behaviors. It employs a collaborative and stakeholder-based model building methodology to create a visual depiction of the system as a whole. SDM can also enable researchers to run dynamic simulations to provide evidence of anticipated or unanticipated outcomes that could result from policy and programmatic intervention. SDM may advance rehabilitation research by providing greater insights into the structure and dynamics of WD systems while helping to understand inherent complexity. Challenges related to data availability, determining validity, and the extensive time and technical skill requirements for model building may limit SDM's use in the field and should be considered. Contemporary work disability (WD) models provide limited insight into complexity associated with WD processes. System dynamics modeling (SDM) has the potential to capture complexity through a stakeholder-based approach that generates a simulation model consisting of multiple feedback loops. SDM may enable WD researchers and practitioners to understand the structure and behavior of the WD system as a whole, and inform development of improved strategies to manage straightforward and complex WD cases.

Effects of model complexity and priors on estimation using sequential importance sampling/resampling for species conservation

USGS Publications Warehouse

Dunham, Kylee; Grand, James B.

2016-01-01

We examined the effects of complexity and priors on the accuracy of models used to estimate ecological and observational processes, and to make predictions regarding population size and structure. State-space models are useful for estimating complex, unobservable population processes and making predictions about future populations based on limited data. To better understand the utility of state space models in evaluating population dynamics, we used them in a Bayesian framework and compared the accuracy of models with differing complexity, with and without informative priors using sequential importance sampling/resampling (SISR). Count data were simulated for 25 years using known parameters and observation process for each model. We used kernel smoothing to reduce the effect of particle depletion, which is common when estimating both states and parameters with SISR. Models using informative priors estimated parameter values and population size with greater accuracy than their non-informative counterparts. While the estimates of population size and trend did not suffer greatly in models using non-informative priors, the algorithm was unable to accurately estimate demographic parameters. This model framework provides reasonable estimates of population size when little to no information is available; however, when information on some vital rates is available, SISR can be used to obtain more precise estimates of population size and process. Incorporating model complexity such as that required by structured populations with stage-specific vital rates affects precision and accuracy when estimating latent population variables and predicting population dynamics. These results are important to consider when designing monitoring programs and conservation efforts requiring management of specific population segments.

Cu(II) potentiation of Alzheimer Abeta1-40 cytotoxicity and transition on its secondary structure.

PubMed

Dai, Xue-Ling; Sun, Ya-Xuan; Jiang, Zhao-Feng

2006-11-01

Mounting evidence has shown that dyshomeostasis of the redox-active biometals such as Cu and Fe can lead to oxidative stress, which plays a key role in the neuropathology of Alzheimer' disease (AD). Here we demonstrate that with the formation of Cu(II).beta1-40 complexes, copper markedly potentiates the neurotoxicity exhibited by beta-amyloid peptide (Ab). A greater amount of hydrogen peroxide was released when Cu(II).beta1-40 complexes was added to the xanthine oxidase/xanthine system detected by potassium iodide spectrophotometry. Copper bound to Abeta1-40 was observed by electron paramagnetic resonance (EPR) spectroscopy. Circular dichroism (CD) studies indicated that copper chelation could cause a structural transition of Abeta. The addition of copper to Ab introduced an increase on beta-sheet as well as alpha-helix, which may be responsible for the aggregation of Abeta. We hypothesized that Abeta aggregation induced by copper may be responsible for local injury in AD. The interaction between Cu(2+) and Ab also provides a possible mechanism for the enrichment of metal ions in amyloid plaques in the AD brain.

End of the chain? Rugosity and fine-scale bathymetry from existing underwater digital imagery using structure-from-motion (SfM) technology

USGS Publications Warehouse

Storlazzi, Curt; Dartnell, Peter; Hatcher, Gerry; Gibbs, Ann E.

2016-01-01

The rugosity or complexity of the seafloor has been shown to be an important ecological parameter for fish, algae, and corals. Historically, rugosity has been measured either using simple and subjective manual methods such as ‘chain-and-tape’ or complicated and expensive geophysical methods. Here, we demonstrate the application of structure-from-motion (SfM) photogrammetry to generate high-resolution, three-dimensional bathymetric models of a fringing reef from existing underwater video collected to characterize the seafloor. SfM techniques are capable of achieving spatial resolution that can be orders of magnitude greater than large-scale lidar and sonar mapping of coral reef ecosystems. The resulting data provide finer-scale measurements of bathymetry and rugosity that are more applicable to ecological studies of coral reefs than provided by the more expensive and time-consuming geophysical methods. Utilizing SfM techniques for characterizing the benthic habitat proved to be more effective and quantitatively powerful than conventional methods and thus might portend the end of the ‘chain-and-tape’ method for measuring benthic complexity.

Characterizing air quality data from complex network perspective.

PubMed

Fan, Xinghua; Wang, Li; Xu, Huihui; Li, Shasha; Tian, Lixin

2016-02-01

Air quality depends mainly on changes in emission of pollutants and their precursors. Understanding its characteristics is the key to predicting and controlling air quality. In this study, complex networks were built to analyze topological characteristics of air quality data by correlation coefficient method. Firstly, PM2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) indexes of eight monitoring sites in Beijing were selected as samples from January 2013 to December 2014. Secondly, the C-C method was applied to determine the structure of phase space. Points in the reconstructed phase space were considered to be nodes of the network mapped. Then, edges were determined by nodes having the correlation greater than a critical threshold. Three properties of the constructed networks, degree distribution, clustering coefficient, and modularity, were used to determine the optimal value of the critical threshold. Finally, by analyzing and comparing topological properties, we pointed out that similarities and difference in the constructed complex networks revealed influence factors and their different roles on real air quality system.

Kinematic analysis of melange fabrics: Examples and applications from the McHugh Complex, Kenai Peninsula, Alaska

USGS Publications Warehouse

Kusky, T.M.; Bradley, D.C.

1999-01-01

Permian to Cretaceous melange of the McHugh Complex on the Kenai Peninsula, south-central Alaska includes blocks and belts of graywacke, argillite, limestone, chert, basalt, gabbro, and ultramafic rocks, intruded by a variety of igneous rocks. An oceanic plate stratigraphy is repeated hundreds of times across the map area, but most structures at the outcrop scale extend lithological layering. Strong rheological units occur as blocks within a matrix that flowed around the competent blocks during deformation, forming broken formation and melange. Deformation was noncoaxial, and disruption of primary layering was a consequence of general strain driven by plate convergence in a relatively narrow zone between the overriding accretionary wedge and the downgoing, generally thinly sedimented oceanic plate. Soft-sediment deformation processes do not appear to have played a major role in the formation of the melange. A model for deformation at the toe of the wedge is proposed in which layers oriented at low angles to ??1 are contracted in both the brittle and ductile regimes, layers at 30-45??to ??1 are extended in the brittle regime and contracted in the ductile regime, and layers at angles greater than 45??to ??1 are extended in both the brittle and ductile regimes. Imbrication in thrust duplexes occurs at deeper levels within the wedge. Many structures within melange of the McHugh Complex are asymmetric and record kinematic information consistent with the inferred structural setting in an accretionary wedge. A displacement field for the McHugh Complex on the lower Kenai Peninsula includes three belts: an inboard belt of Late Triassic rocks records west-to-east-directed slip of hanging walls, a central belt of predominantly Early Jurassic rocks records north-south directed displacements, and Early Cretaceous rocks in an outboard belt preserve southwest-northeast directed slip vectors. Although precise ages of accretion are unknown, slip directions are compatible with inferred plate motions during the general time frame of accretion of the McHugh Complex. The slip vectors are interpreted to preserve the convergence directions between the overriding and underriding plates, which became more oblique with time. They are not considered indicative of strain partitioning into belts of orogen-parallel and orogen-perpendicular displacements, because the kinematic data are derived from the earliest preserved structures, whereas fabrics related to strain partitioning would be expected to be superimposed on earlier accretion-related fabrics.Permian to Cretaceous melange of the McHugh Complex on the Kenai Peninsula, south-central Alaska includes blocks and belts of graywacke, argillite, limestone, chert, basalt, gabbro, and ultramafic rocks, intruded by a variety of igneous rocks. An oceanic plate stratigraphy is repeated hundreds of times across the map area, but most structures at the outcrop scale extend lithological layering. Strong rheological units occur as blocks within a matrix that flowed around the competent blocks during deformation, forming broken formation and melange. Deformation was noncoaxial, and disruption of primary layering was a consequence of general strain driven by plate convergence in a relatively narrow zone between the overriding accretionary wedge and the downgoing, generally thinly sedimented oceanic plate. Soft-sediment deformation processes do not appear to have played a major role in the formation of the melange. A model for deformation at the toe of the wedge is proposed in which layers oriented at low angles to ??1 are contracted in both the brittle and ductile regimes, layers at 30-45?? to ??1 are extended in the brittle regime and contracted in the ductile regime, and layers at angles greater than 45?? to ??1 are extended in both the brittle and ductile regimes. Imbrication in thrust duplexes occurs at deeper levels within the wedge. Many structures within melange of the McHugh Complex are asymmetric and record

Three-part joint modeling methods for complex functional data mixed with zero-and-one-inflated proportions and zero-inflated continuous outcomes with skewness.

PubMed

Li, Haocheng; Staudenmayer, John; Wang, Tianying; Keadle, Sarah Kozey; Carroll, Raymond J

2018-02-20

We take a functional data approach to longitudinal studies with complex bivariate outcomes. This work is motivated by data from a physical activity study that measured 2 responses over time in 5-minute intervals. One response is the proportion of time active in each interval, a continuous proportions with excess zeros and ones. The other response, energy expenditure rate in the interval, is a continuous variable with excess zeros and skewness. This outcome is complex because there are 3 possible activity patterns in each interval (inactive, partially active, and completely active), and those patterns, which are observed, induce both nonrandom and random associations between the responses. More specifically, the inactive pattern requires a zero value in both the proportion for active behavior and the energy expenditure rate; a partially active pattern means that the proportion of activity is strictly between zero and one and that the energy expenditure rate is greater than zero and likely to be moderate, and the completely active pattern means that the proportion of activity is exactly one, and the energy expenditure rate is greater than zero and likely to be higher. To address these challenges, we propose a 3-part functional data joint modeling approach. The first part is a continuation-ratio model to reorder the ordinal valued 3 activity patterns. The second part models the proportions when they are in interval (0,1). The last component specifies the skewed continuous energy expenditure rate with Box-Cox transformations when they are greater than zero. In this 3-part model, the regression structures are specified as smooth curves measured at various time points with random effects that have a correlation structure. The smoothed random curves for each variable are summarized using a few important principal components, and the association of the 3 longitudinal components is modeled through the association of the principal component scores. The difficulties in handling the ordinal and proportional variables are addressed using a quasi-likelihood type approximation. We develop an efficient algorithm to fit the model that also involves the selection of the number of principal components. The method is applied to physical activity data and is evaluated empirically by a simulation study. Copyright © 2017 John Wiley & Sons, Ltd.

Optical and Electronic Properties of Nano-Materials from First Principles Computation

NASA Astrophysics Data System (ADS)

Deslippe, Jack Richard

This dissertation examines effects of land management on forest structure at both the stand and landscape scales. Specifically, it investigates the effect of five types of silvicultural cutting (clear-cut, improvement thinning, diameter-limited thinning from the top, diameter-limited thinning from below, and the initial cut of a shelterwood system) on forest structural diversity and carbon storage in mixed oak hardwood forests of Pennsylvania. Furthermore, it develops LiDAR (Light Detecting and Ranging) techniques to quantify forest structural diversity at a landscape level to examine forest structure, with comparisons between eco-provinces and management types. At the stand scale, it was found that structural resilience to silvicultural disturbances was greater than compositional resilience, resulting in forests that appeared to recover quickly from disturbance but were compositionally altered. More intense disturbances caused greater changes in forest structure and composition, requiring longer to return to near predisturbance conditions; however, the forest strata disturbed also influenced the disturbance severity and therefore the forest's response. This study demonstrated that silvicultural cutting may be used to increase structural diversity at the stand level (e.g., establishment cut of a shelterwood system); however, this comes at the cost of an increase in shade-tolerant regeneration to the detriment of economically and ecologically valuable mid-successional species. The long-term outcomes of partial cuts were complex and context specific, and this complexity may be useful for maintaining or increasing structural complexity at the landscape level. A variety of silvicultural techniques should be implemented to achieve management objectives of increased forest structural diversity. In terms of carbon storage at the stand scale, although the clearcutting treatment had the highest carbon periodic annual increment (cPAI) in the first 15 years post harvest, it was projected to store considerably less carbon in the long term (over 100-years) than the other treatments. The projected low carbon storage in this treatment is likely due to a shift in species composition to early successional species that store less carbon per tree. Amongst the partial cutting methods, the improvement thin was the best option with moderate timber harvest rates, moderately high cPAI in the first 15 years post-harvest and relatively high carbon storage in the long-term; however, refraining from cutting remains the best option for carbon storage if the forest is in the aggradation phase. Poor silvicultural decisions may lead to reduced carbon storage of forest stands in the long-term, reducing the effectiveness of these forest carbon sinks for climate change mitigation. To explore forest structure at the landscape level, a method to map forest canopy structure over large areas was developed using low-density topographic Light Detection And Ranging (LiDAR) data and orthographic photography collected for Pennsylvania as part of PAMAP (Pennsylvania Map Program). K-means clustering of LiDAR statistics on a grid basis was used in conjunction with multinomial logistic regression to develop a LiDAR Canopy Structure Topology (LCST). The fourteen resulting LCST types reflect vegetation top height and canopy structural complexity with a correct classification rate of 96%. This LCST provides cost-effective forest structure information by relying on remote sensing data freely available for the entire state of Pennsylvania and that could be widely utilized for forest, wildlife and landscape planning. Furthermore, the methods developed here may be adapted to map forest structure in other contexts with different LiDAR data sets. This LCST was then mapped over 20 large landscapes within Pennsylvania, and these contrasting landscapes analyzed to investigate the influence of both site and four differing land management types (non-government, Bureau of Forestry, Bureau of State Parks and Pennsylvania Game Commission) on forest structure. It was found that at the local scale both topography and land management type had significant influences over forest structure; however, combined they only explained 32% of the variation in forest structure. At the landscape scale, there were significant differences in forest landscape structure between both Bailey's eco-provinces and management types. Specifically, non-government forests showed evidence of forest structure fragmentation. These non-government forested lands contained a higher proportion of short vegetation types, higher patch density, and greater heterogeneity of neighboring patches. This within-forest fragmentation is likely to have implications for both biodiversity and ecosystem services. Together, the studies presented in this dissertation show that management has a great impact on forest structure and carbon storage at both the stand and landscape levels. Management modifies the underlying influence of the environment, resulting in the realized forest structure patterns on the landscape. Therefore managers need to consciously incorporate these considerations into their management decisions at both the stand and landscape levels. Furthermore, this dissertation shows that despite its shortcomings, topographic LiDAR can be used for landscape scale vegetation studies in addition to topographic modeling. (Abstract shortened by UMI.).

Profile of the intestinal mucosal corticosteroid receptors in the domestic duck

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiBattista, J.A.; Mehdi, A.Z.; Sandor, T.

The corticosteroid receptor profile of the intestinal tract of the domestic duck (maintained on either a low-sodium (LS) or a high-sodium (HS) diet) was investigated. Using tritiated triamcinolone acetonide (TA), corticosterone, or aldosterone as ligands, cytoplasmic mineralocorticoid receptors (MR, type I) and glucocorticoid receptors (GR, type II) were found in the mucosal cytosol of the jejunum and colon. The diet little influenced the GR binding parameters, while the MR (aldosterone) binding parameters showed a down-regulation following LS diets. The competition hierarchy of radioinert steroids on the formation of the (TH)corticosterone-receptor complex was corticosterone = cortisol = 11-deoxycorticosterone greater than aldosteronemore » = TA = dexamethasone much greater than 11-deoxycortisol; with (TH)aldosterone, the competition was corticosterone = progesterone = 11-deoxycorticosterone greater than aldosterone = cortisol = TA = dexamethasone greater than 11-deoxycortisol greater than 11-dehydrocorticosterone. On linear sucrose gradients, receptor-ligand complexes sedimented with a single peak at 8.5 S (hypotonic gradient) and 4.0-4.5 S (hypertonic gradient), respectively. Heat-activated (TH)TA- and (TH)aldosterone-receptor complexes bound avidly to DNA-cellulose and, upon ion-exchange chromatography on DEAE-Sephacel, the presence of the negatively charged unactivated and the more positively charged activated complexes could be shown.« less

Prolonged Cannabidiol Treatment Effects on Hippocampal Subfield Volumes in Current Cannabis Users.

PubMed

Beale, Camilla; Broyd, Samantha J; Chye, Yann; Suo, Chao; Schira, Mark; Galettis, Peter; Martin, Jennifer H; Yücel, Murat; Solowij, Nadia

2018-01-01

Introduction: Chronic cannabis use is associated with neuroanatomical alterations in the hippocampus. While adverse impacts of cannabis use are generally attributed to Δ 9 -tetrahydrocannabinol, emerging naturalistic evidence suggests cannabidiol (CBD) is neuroprotective and may ameliorate brain harms associated with cannabis use, including protection from hippocampal volume loss. This study examined whether prolonged administration of CBD to regular cannabis users within the community could reverse or reduce the characteristic hippocampal harms associated with chronic cannabis use. Materials and Methods: Eighteen regular cannabis users participated in an ∼10-week open-label pragmatic trial involving daily oral administration of 200 mg CBD, with no change to their ongoing cannabis use requested. Participants were assessed at baseline and post-CBD treatment using structural magnetic resonance imaging. Automated longitudinal hippocampal segmentation was performed to assess volumetric change over the whole hippocampus and within 12 subfields. Results: No change was observed in left or right hippocampus as a whole. However, left subicular complex (parasubiculum, presubiculum, and subiculum) volume significantly increased from baseline to post-treatment ( p =0.017 uncorrected) by 1.58% (Cohen's d =0.63; 2.83% in parasubiculum). Heavy cannabis users demonstrated marked growth in the left subicular complex, predominantly within the presubiculum, and right cornu ammonis (CA)1 compared to lighter users. Associations between greater right subicular complex and total hippocampal volume and higher plasma CBD concentration were evident, particularly in heavy users. Conclusions: Our findings suggest a restorative effect of CBD on the subicular and CA1 subfields in current cannabis users, especially those with greater lifetime exposure to cannabis. While replication is required in a larger, placebo-controlled trial, these findings support a protective role of CBD against brain structural harms conferred by chronic cannabis use. Furthermore, these outcomes suggest that CBD may be a useful adjunct in treatments for cannabis dependence and may be therapeutic for a range of clinical disorders characterized by hippocampal pathology (e.g., schizophrenia, Alzheimer's disease, and major depressive disorder).

Prolonged Cannabidiol Treatment Effects on Hippocampal Subfield Volumes in Current Cannabis Users

PubMed Central

Beale, Camilla; Broyd, Samantha J.; Chye, Yann; Suo, Chao; Schira, Mark; Galettis, Peter; Martin, Jennifer H.; Yücel, Murat; Solowij, Nadia

2018-01-01

Abstract Introduction: Chronic cannabis use is associated with neuroanatomical alterations in the hippocampus. While adverse impacts of cannabis use are generally attributed to Δ9-tetrahydrocannabinol, emerging naturalistic evidence suggests cannabidiol (CBD) is neuroprotective and may ameliorate brain harms associated with cannabis use, including protection from hippocampal volume loss. This study examined whether prolonged administration of CBD to regular cannabis users within the community could reverse or reduce the characteristic hippocampal harms associated with chronic cannabis use. Materials and Methods: Eighteen regular cannabis users participated in an ∼10-week open-label pragmatic trial involving daily oral administration of 200 mg CBD, with no change to their ongoing cannabis use requested. Participants were assessed at baseline and post-CBD treatment using structural magnetic resonance imaging. Automated longitudinal hippocampal segmentation was performed to assess volumetric change over the whole hippocampus and within 12 subfields. Results: No change was observed in left or right hippocampus as a whole. However, left subicular complex (parasubiculum, presubiculum, and subiculum) volume significantly increased from baseline to post-treatment (p=0.017 uncorrected) by 1.58% (Cohen's d=0.63; 2.83% in parasubiculum). Heavy cannabis users demonstrated marked growth in the left subicular complex, predominantly within the presubiculum, and right cornu ammonis (CA)1 compared to lighter users. Associations between greater right subicular complex and total hippocampal volume and higher plasma CBD concentration were evident, particularly in heavy users. Conclusions: Our findings suggest a restorative effect of CBD on the subicular and CA1 subfields in current cannabis users, especially those with greater lifetime exposure to cannabis. While replication is required in a larger, placebo-controlled trial, these findings support a protective role of CBD against brain structural harms conferred by chronic cannabis use. Furthermore, these outcomes suggest that CBD may be a useful adjunct in treatments for cannabis dependence and may be therapeutic for a range of clinical disorders characterized by hippocampal pathology (e.g., schizophrenia, Alzheimer's disease, and major depressive disorder). PMID:29682609

Impact of various lipophilic substituents on ruthenium(II), rhodium(III) and iridium(III) salicylaldimine-based complexes: synthesis, in vitro cytotoxicity studies and DNA interactions.

PubMed

Cassells, Irwin; Stringer, Tameryn; Hutton, Alan T; Prince, Sharon; Smith, Gregory S

2018-05-30

A series of bidentate salicylaldimine ligands was prepared and reacted with either [RuCl(µ-Cl)(p-cymene)] 2 , [RhCl(µ-Cl)(Cp*)] 2 or [IrCl(µ-Cl)(Cp*)] 2 . All of the compounds were characterised using an array of spectroscopic and analytical techniques, namely, nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy and mass spectrometry. Single crystal X-ray diffraction (XRD) was used to confirm the bidentate coordination mode of the salicylaldimine ligand to the metal centre. The platinum group metal (PGM) complexes were screened against the MCF7 breast cancer cell line. The ruthenium and iridium salicylaldimine complexes showed comparable or greater cytotoxicity than cisplatin against the MCF7 cancer cells, as well as greater cytotoxicity than their rhodium counterparts. Three of the salicylaldimine complexes showed potent activity in the range 18-21 µM. Two of these complexes had a greater affinity for cancerous cells than for CHO non-cancerous cells (SI > 4). Preliminary mechanistic studies suggest that the ruthenium complexes undergo solvation prior to 5'-GMP binding, whereas the iridium complexes were inert to the solvation process.

[Ligands of cholinesterases of ephedrine and pseudoephedrine structure].

PubMed

Basova, N E; Kormilitsin, B N; Perchenok, A Yu; Rozengatt, E V; Saakov, V S; Suvorov, A A

2013-01-01

The paper is a review of literature data on interaction of the mammalian erythrocyte acetylcholinesterase and blood serum butyrylcholinesterase with a group of isomer complex ester derivatives (acetates, propionates, butyrates, valerates, and isobutyrates) of bases and iodomethylates of ephedrine and its enantiomer pseudoephedrine. For 20 alkaloid monoesters, parameters of enzymatic hydrolysis are determined and their certain specificity toward acetylcholinesterase is revealed, whereas 5 diesters of iodomethylates of pseudoephedrine were hydrolyzed only by butyrylcholinesterase. The studied 20 aklaloid diesters and 10 trimethylammonium derivatives turned out to be non-competitive reversible inhibitors of acetylcholinesterase and competitive inhibitors of butyrylcholinesterase. The performed for the first time isomer and enantiomer analysis "structure-efficiency" has shown that in most cases it is possible to state the greater comlementarity of the catalytical surface of enzymes for ligands of the pseudoephedrine structure, such differentiation being realized more often at the reversible inhibition of enzymes. pseudoephedrine.

Evaluating Treatment and Generalization Patterns of Two Theoretically Motivated Sentence Comprehension Therapies

PubMed Central

Des Roches, Carrie A.; Vallila-Rohter, Sofia; Villard, Sarah; Tripodis, Yorghos; Caplan, David

2016-01-01

Purpose The current study examined treatment outcomes and generalization patterns following 2 sentence comprehension therapies: object manipulation (OM) and sentence-to-picture matching (SPM). Findings were interpreted within the framework of specific deficit and resource reduction accounts, which were extended in order to examine the nature of generalization following treatment of sentence comprehension deficits in aphasia. Method Forty-eight individuals with aphasia were enrolled in 1 of 8 potential treatment assignments that varied by task (OM, SPM), complexity of trained sentences (complex, simple), and syntactic movement (noun phrase, wh-movement). Comprehension of trained and untrained sentences was probed before and after treatment using stimuli that differed from the treatment stimuli. Results Linear mixed-model analyses demonstrated that, although both OM and SPM treatments were effective, OM resulted in greater improvement than SPM. Analyses of covariance revealed main effects of complexity in generalization; generalization from complex to simple linguistically related sentences was observed both across task and across movement. Conclusions Results are consistent with the complexity account of treatment efficacy, as generalization effects were consistently observed from complex to simpler structures. Furthermore, results provide support for resource reduction accounts that suggest that generalization can extend across linguistic boundaries, such as across movement type. PMID:27997950

Revitalizing Complex Analysis: A Transition-to-Proof Course Centered on Complex Topics

ERIC Educational Resources Information Center

Sachs, Robert

2017-01-01

A new transition course centered on complex topics would help in revitalizing complex analysis in two ways: first, provide early exposure to complex functions, sparking greater interest in the complex analysis course; second, create extra time in the complex analysis course by eliminating the "complex precalculus" part of the course. In…

Functional consequences of structural differences in stingray sensory systems. Part I: mechanosensory lateral line canals.

PubMed

Jordan, Laura K; Kajiura, Stephen M; Gordon, Malcolm S

2009-10-01

Short range hydrodynamic and electrosensory signals are important during final stages of prey capture in elasmobranchs (sharks, skates and rays), and may be particularly useful for dorso-ventrally flattened batoids with mouths hidden from their eyes. In stingrays, both the lateral line canal and electrosensory systems are highly modified and complex with significant differences on ventral surfaces that relate to feeding ecology. This study tests functional hypotheses based on quantified differences in sensory system morphology of three stingray species, Urobatis halleri, Myliobatis californica and Pteroplatytrygon violacea. Part I investigates the mechanosensory lateral line canal system whereas part II focuses on the electrosensory system. Stingray lateral line canals include both pored and non-pored sections and differ in branching complexity and distribution. A greater proportion of pored canals and high pore numbers were predicted to correspond to increased response to water flow. Behavioral experiments were performed to compare responses of stingrays to weak water jets mimicking signals produced by potential prey at velocities of 10-20 cm s(-1). Bat rays, M. californica, have the most complex and broadly distributed pored canal network and demonstrated both the highest response rate and greater response intensity to water jet signals. Results suggest that U. halleri and P. violacea may rely on additional sensory input, including tactile and visual cues, respectively, to initiate stronger feeding responses. These results suggest that stingray lateral line canal morphology can indicate detection capabilities through responsiveness to weak water jets.

The Influence of Coral Reef Benthic Condition on Associated Fish Assemblages

PubMed Central

Chong-Seng, Karen M.; Mannering, Thomas D.; Pratchett, Morgan S.; Bellwood, David R.; Graham, Nicholas A. J.

2012-01-01

Accumulative disturbances can erode a coral reef’s resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs around the inner Seychelles islands. Specifically, relationships between benthic composition and the underlying substrata, as well as the associated fish assemblages were assessed. High variability in benthic composition was found among reefs, with a gradient from high coral cover (up to 58%) and high structural complexity to high macroalgae cover (up to 95%) and low structural complexity at the extremes. This gradient was associated with declining species richness of fishes, reduced diversity of fish functional groups, and lower abundance of corallivorous fishes. There were no reciprocal increases in herbivorous fish abundances, and relationships with other fish functional groups and total fish abundance were weak. Reefs grouping at the extremes of complex coral habitats or low-complexity macroalgal habitats displayed markedly different fish communities, with only two species of benthic invertebrate feeding fishes in greater abundance in the macroalgal habitat. These results have negative implications for the continuation of many coral reef ecosystem processes and services if more reefs shift to extreme degraded conditions dominated by macroalgae. PMID:22870294

The influence of coral reef benthic condition on associated fish assemblages.

PubMed

Chong-Seng, Karen M; Mannering, Thomas D; Pratchett, Morgan S; Bellwood, David R; Graham, Nicholas A J

2012-01-01

Accumulative disturbances can erode a coral reef's resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs around the inner Seychelles islands. Specifically, relationships between benthic composition and the underlying substrata, as well as the associated fish assemblages were assessed. High variability in benthic composition was found among reefs, with a gradient from high coral cover (up to 58%) and high structural complexity to high macroalgae cover (up to 95%) and low structural complexity at the extremes. This gradient was associated with declining species richness of fishes, reduced diversity of fish functional groups, and lower abundance of corallivorous fishes. There were no reciprocal increases in herbivorous fish abundances, and relationships with other fish functional groups and total fish abundance were weak. Reefs grouping at the extremes of complex coral habitats or low-complexity macroalgal habitats displayed markedly different fish communities, with only two species of benthic invertebrate feeding fishes in greater abundance in the macroalgal habitat. These results have negative implications for the continuation of many coral reef ecosystem processes and services if more reefs shift to extreme degraded conditions dominated by macroalgae.

Fragmentation alters stream fish community structure in dendritic ecological networks.

PubMed

Perkin, Joshuah S; Gido, Keith B

2012-12-01

Effects of fragmentation on the ecology of organisms occupying dendritic ecological networks (DENs) have recently been described through both conceptual and mathematical models, but few hypotheses have been tested in complex, real-world ecosystems. Stream fishes provide a model system for assessing effects of fragmentation on the structure of communities occurring within DENs, including how fragmentation alters metacommunity dynamics and biodiversity. A recently developed habitat-availability measure, the "dendritic connectivity index" (DCI), allows for assigning quantitative measures of connectivity in DENs regardless of network extent or complexity, and might be used to predict fish community response to fragmentation. We characterized stream fish community structure in 12 DENs in the Great Plains, USA, during periods of dynamic (summer) and muted (fall) discharge regimes to test the DCI as a predictive model of fish community response to fragmentation imposed by road crossings. Results indicated that fish communities in stream segments isolated by road crossings had reduced species richness (alpha diversity) relative to communities that maintained connectivity with the surrounding DEN during summer and fall. Furthermore, isolated communities had greater dissimilarity (beta diversity) to downstream sites notisolated by road crossings during summer and fall. Finally, dissimilarity among communities within DENs decreased as a function of increased habitat connectivity (measured using the DCI) for summer and fall, suggesting that communities within highly connected DENs tend to be more homogeneous. Our results indicate that the DCI is sensitive to community effects of fragmentation in riverscapes and might be used by managers to predict ecological responses to changes in habitat connectivity. Moreover, our findings illustrate that relating structural connectivity of riverscapes to functional connectivity among communities might aid in maintaining metacommunity dynamics and biodiversity in complex dendritic ecosystems.

Extracting, Tracking, and Visualizing Magnetic Flux Vortices in 3D Complex-Valued Superconductor Simulation Data.

PubMed

Guo, Hanqi; Phillips, Carolyn L; Peterka, Tom; Karpeyev, Dmitry; Glatz, Andreas

2016-01-01

We propose a method for the vortex extraction and tracking of superconducting magnetic flux vortices for both structured and unstructured mesh data. In the Ginzburg-Landau theory, magnetic flux vortices are well-defined features in a complex-valued order parameter field, and their dynamics determine electromagnetic properties in type-II superconductors. Our method represents each vortex line (a 1D curve embedded in 3D space) as a connected graph extracted from the discretized field in both space and time. For a time-varying discrete dataset, our vortex extraction and tracking method is as accurate as the data discretization. We then apply 3D visualization and 2D event diagrams to the extraction and tracking results to help scientists understand vortex dynamics and macroscale superconductor behavior in greater detail than previously possible.

Comparison of the biomechanical properties of rottweiler and racing greyhound cranial cruciate ligaments.

PubMed

Wingfield, C; Amis, A A; Stead, A C; Law, H T

2000-07-01

An in vitro study of rottweiler and racing greyhound cranial cruciate ligaments revealed that the rottweiler ligaments had a significantly greater cross-sectional area at their distal attachments. Mechanical testing showed that the ultimate load related to body mass was significantly higher in the extended racing greyhound stifle during cranial tibial loading to failure, as were linear stiffness, tensile strength and tangent modulus. During ligament axis loading to failure, the only significant difference in structural and mechanical properties recorded between the two breeds was a greater ultimate strain for the greyhound ligament with the stifle joint flexed. Energy absorbed by the ligament complex at failure during cranial tibial loading was twice that for ligament axis loading for both breeds. The clinical significance is that the rottweiler cranial cruciate ligament is more vulnerable to damage as it requires half the load per unit body mass that the greyhound requires to cause a rupture.

Staufen1 senses overall transcript secondary structure to regulate translation

PubMed Central

Ricci, Emiliano P; Kucukural, Alper; Cenik, Can; Mercier, Blandine C; Singh, Guramrit; Heyer, Erin E; Ashar-Patel, Ami; Peng, Lingtao; Moore, Melissa J

2015-01-01

Human Staufen1 (Stau1) is a double-stranded RNA (dsRNA)-binding protein implicated in multiple post-transcriptional gene-regulatory processes. Here we combined RNA immunoprecipitation in tandem (RIPiT) with RNase footprinting, formaldehyde cross-linking, sonication-mediated RNA fragmentation and deep sequencing to map Staufen1-binding sites transcriptome wide. We find that Stau1 binds complex secondary structures containing multiple short helices, many of which are formed by inverted Alu elements in annotated 3′ untranslated regions (UTRs) or in ‘strongly distal’ 3′ UTRs. Stau1 also interacts with actively translating ribosomes and with mRNA coding sequences (CDSs) and 3′ UTRs in proportion to their GC content and propensity to form internal secondary structure. On mRNAs with high CDS GC content, higher Stau1 levels lead to greater ribosome densities, thus suggesting a general role for Stau1 in modulating translation elongation through structured CDS regions. Our results also indicate that Stau1 regulates translation of transcription-regulatory proteins. PMID:24336223

Synchrotron Protein Footprinting Supports Substrate Translocation by ClpA via ATP-Induced Movements of the D2 Loop

PubMed Central

Bohon, Jen; Jennings, Laura D.; Phillips, Christine M.; Licht, Stuart; Chance, Mark R.

2010-01-01

SUMMARY Synchrotron x-ray protein footprinting is used to study structural changes upon formation of the ClpA hexamer. Comparative solvent accessibilities between ClpA monomer and ClpA hexamer samples are in agreement throughout most of the sequence with calculations based on two previously proposed hexameric models. The data differ substantially from the proposed models in two parts of the structure: the D1 sensor 1 domain and the D2 loop region. The results suggest that these two regions can access alternate conformations in which their solvent protection is greater than in the structural models based on crystallographic data. In combination with previously reported structural data, the footprinting data provide support for a revised model in which the D2 loop contacts the D1 sensor 1 domain in the ATP-bound form of the complex. These data provide the first direct experimental support for the nucleotide-dependent D2 loop conformational change previously proposed to mediate substrate translocation. PMID:18682217

Utilizing food effects to overcome challenges in delivery of lipophilic bioactives: structural design of medical and functional foods.

PubMed

McClements, David Julian

2013-12-01

The oral bioavailability of many lipophilic bioactives, such as pharmaceuticals and nutraceuticals, is relatively low due to their poor solubility, permeability and/or chemical stability within the human gastrointestinal tract (GIT). The oral bioavailability of lipophilic bioactives can be improved by designing food matrices that control their release, solubilization, transport and absorption within the GIT. This article discusses the challenges associated with delivering lipophilic bioactive components, the impact of food composition and structure on oral bioavailability and the design of functional and medical foods for improving the oral bioavailability of lipophilic bioactives. Food-based delivery systems can be used to improve the oral bioavailability of lipophilic bioactives. There are a number of potential advantages to delivering lipophilic bioactives using functional or medical foods: greater compliance than conventional delivery forms; increased bioavailability and efficacy; and reduced variability in biological effects. However, food matrices are structurally complex multicomponent materials and research is still needed to identify optimum structures and compositions for particular bioactives.

A Versatile Platform for Nanotechnology Based on Circular Permutation of a Chaperonin Protein

NASA Technical Reports Server (NTRS)

Paavola, Chad; McMillan, Andrew; Trent, Jonathan; Chan, Suzanne; Mazzarella, Kellen; Li, Yi-Fen

2004-01-01

A number of protein complexes have been developed as nanoscale templates. These templates can be functionalized using the peptide sequences that bind inorganic materials. However, it is difficult to integrate peptides into a specific position within a protein template. Integrating intact proteins with desirable binding or catalytic activities is an even greater challenge. We present a general method for modifying protein templates using circular permutation so that additional peptide sequence can be added in a wide variety of specific locations. Circular permutation is a reordering of the polypeptide chain such that the original termini are joined and new termini are created elsewhere in the protein. New sequence can be joined to the protein termini without perturbing the protein structure and with minimal limitation on the size and conformation of the added sequence. We have used this approach to modify a chaperonin protein template, placing termini at five different locations distributed across the surface of the protein complex. These permutants are competent to form the double-ring structures typical of chaperonin proteins. The permuted double-rings also form the same assemblies as the unmodified protein. We fused a fluorescent protein to two representative permutants and demonstrated that it assumes its active structure and does not interfere with assembly of chaperonin double-rings.

Benthic Crustacea from tropical and temperate reef locations: differences in assemblages and their relationship with habitat structure

NASA Astrophysics Data System (ADS)

Kramer, Michael J.; Bellwood, David R.; Taylor, Richard B.; Bellwood, Orpha

2017-09-01

Tropical and temperate marine habitats have long been recognised as fundamentally different system, yet comparative studies are rare, particularly for small organisms such as Crustacea. This study investigates the ecological attributes (abundance, biomass and estimated productivity) of benthic Crustacea in selected microhabitats from a tropical and a temperate location, revealing marked differences in the crustacean assemblages. In general, microhabitats from the tropical location (dead coral, the epilithic algal matrix [algal turfs] and sand) supported high abundances of small individuals (mean length = 0.53 mm vs. 0.96 mm in temperate microhabitats), while temperate microhabitats (the brown seaweed Carpophyllum sp., coralline turf and sand) had substantially greater biomasses of crustaceans and higher estimated productivity rates. In both locations, the most important microhabitats for crustaceans (per unit area) were complex structures: tropical dead coral and temperate Carpophyllum sp. It appears that the differences between microhabitats are largely driven by the size and relative abundance of key crustacean groups. Temperate microhabitats have a higher proportion of relatively large Peracarida (Amphipoda and Isopoda), whereas tropical microhabitats are dominated by small detrital- and microalgal-feeding crustaceans (harpacticoid copepods and ostracods). These differences highlight the vulnerability of tropical and temperate systems to the loss of complex benthic structures and their associated crustacean assemblages.

Distributions of vesicular glutamate transporters 1 and 2 in the visual system of tree shrews (Tupaia belangeri)1

PubMed Central

Balaram, P; Isaamullah, M; Petry, HM; Bickford, ME; Kaas, JH

2014-01-01

Vesicular glutamate transporter (VGLUT) proteins regulate the storage and release of glutamate from synapses of excitatory neurons. Two isoforms, VGLUT1 and VGLUT2, are found in most glutamatergic projections across the mammalian visual system, and appear to differentially identify subsets of excitatory projections between visual structures. To expand current knowledge on the distribution of VGLUT isoforms in highly visual mammals, we examined the mRNA and protein expression patterns of VGLUT1 and VGLUT2 in the lateral geniculate nucleus (LGN), superior colliculus, pulvinar complex, and primary visual cortex (V1) in tree shrews (Tupaia belangeri), which are closely related to primates but classified as a separate order (Scandentia). We found that VGLUT1 was distributed in intrinsic and corticothalamic connections, whereas VGLUT2 was predominantly distributed in subcortical and thalamocortical connections. VGLUT1 and VGLUT2 were coexpressed in the LGN and in the pulvinar complex, as well as in restricted layers of V1, suggesting a greater heterogeneity in the range of efferent glutamatergic projections from these structures. These findings provide further evidence that VGLUT1 and VGLUT2 identify distinct populations of excitatory neurons in visual brain structures across mammals. Observed variations in individual projections may highlight the evolution of these connections through the mammalian lineage. PMID:25521420

Urban warming trumps natural enemy regulation of herbivorous pests.

PubMed

Dale, Adam G; Frank, Steven D

Trees provide ecosystem services that counter negative effects of urban habitats on human and environmental health. Unfortunately, herbivorous arthropod pests are often more abundant on urban than rural trees, reducing tree growth, survival, and ecosystem services. Previous research where vegetation complexity was reduced has attributed elevated urban pest abundance to decreased regulation by natural enemies. However, reducing vegetation complexity, particularly the density of overstory trees, also makes cities hotter than natural habitats. We ask how urban habitat characteristics influence an abiotic factor, temperature, and a biotic factor, natural enemy abundance, in regulating the abundance of an urban forest pest, the gloomy scale, (Melanaspis tenebricosa). We used a map of surface temperature to select red maple trees (Acer rubrum) at warmer and cooler sites in Raleigh, North Carolina, USA. We quantified habitat complexity by measuring impervious surface cover, local vegetation structural complexity, and landscape scale vegetation cover around each tree. Using path analysis, we determined that impervious surface (the most important habitat variable) increased scale insect abundance by increasing tree canopy temperature, rather than by reducing natural enemy abundance or percent parasitism. As a mechanism for this response, we found that increasing temperature significantly increases scale insect fecundity and contributes to greater population increase. Specifically, adult female M. tenebricosa egg sets increased by approximately 14 eggs for every 1°C increase in temperature. Climate change models predict that the global climate will increase by 2–3°C in the next 50–100 years, which we found would increase scale insect abundance by three orders of magnitude. This result supports predictions that urban and natural forests will face greater herbivory in the future, and suggests that a primary cause could be direct, positive effects of warming on herbivore fitness rather than altered trophic interactions.

Atomic resolution model of the antibody Fc interaction with the complement C1q component.

PubMed

Schneider, Sebastian; Zacharias, Martin

2012-05-01

The globular C1q heterotrimer is a subunit of the C1 complement factor. Binding of the C1q subunit to the constant (Fc) part of antibody molecules is a first step and key event of complement activation. Although three-dimensional structures of C1q and antibody Fc subunits have been determined experimentally no atomic resolution structure of the C1q-Fc complex is known so far. Based on systematic protein-protein docking searches and Molecular Dynamics simulations a structural model of the C1q-IgG1-Fc-binding geometry has been obtained. The structural model is compatible with available experimental data on the interaction between the two partner proteins. It predicts a binding geometry that involves mainly the B-subunit of the C1q-trimer and both subunits of the IgG1-Fc-dimer with small conformational adjustments with respect to the unbound partners to achieve high surface complementarity. In addition to several charge-charge and polar contacts in the rim region of the interface it also involves nonpolar contacts between the two proteins and is compatible with the carbohydrate moiety of the Fc subunit. The model for the complex structure provides a working model for rationalizing available biochemical data on this important interaction and can form the basis for the design of Fc variants with a greater capacity to activate the complement system for example on binding to cancer cells or other target structures. Copyright © 2012 Elsevier Ltd. All rights reserved.

Obesity-specific neural cost of maintaining gait performance under complex conditions in community-dwelling older adults.

PubMed

Osofundiya, Olufunmilola; Benden, Mark E; Dowdy, Diane; Mehta, Ranjana K

2016-06-01

Recent evidence of obesity-related changes in the prefrontal cortex during cognitive and seated motor activities has surfaced; however, the impact of obesity on neural activity during ambulation remains unclear. The purpose of this study was to determine obesity-specific neural cost of simple and complex ambulation in older adults. Twenty non-obese and obese individuals, 65years and older, performed three tasks varying in the types of complexity of ambulation (simple walking, walking+cognitive dual-task, and precision walking). Maximum oxygenated hemoglobin, a measure of neural activity, was measured bilaterally using a portable functional near infrared spectroscopy system, and gait speed and performance on the complex tasks were also obtained. Complex ambulatory tasks were associated with ~2-3.5 times greater cerebral oxygenation levels and ~30-40% slower gait speeds when compared to the simple walking task. Additionally, obesity was associated with three times greater oxygenation levels, particularly during the precision gait task, despite obese adults demonstrating similar gait speeds and performances on the complex gait tasks as non-obese adults. Compared to existing studies that focus solely on biomechanical outcomes, the present study is one of the first to examine obesity-related differences in neural activity during ambulation in older adults. In order to maintain gait performance, obesity was associated with higher neural costs, and this was augmented during ambulatory tasks requiring greater precision control. These preliminary findings have clinical implications in identifying individuals who are at greater risk of mobility limitations, particularly when performing complex ambulatory tasks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermospheric O/N2 ratio observations obtained over more than four years with the GUVI instrument in the TIMED spacecraft mission

NASA Astrophysics Data System (ADS)

Craven, J. D.; Christensen, A. B.; Paxton, L. J.; Strickland, D. J.

2006-12-01

GUVI observations of the thermospheric column density ratio, O/N2, in the sunlit hemisphere have been made continuously from about Day 50 of 2002 to the present as part of the TIMED spacecraft mission. From these observations have been created organized databases to be used in the creation of analytic models for this parameter. Undesirable attributes within the GUVI data are being eliminated; sun glint at particular solar orientations and penetrating radiation from the South Atlantic magnetic anomaly. The large-scale basic spatial structure includes variations with local time (greater values before local noon), Universal Time (modulation at high latitudes as the dayside auroral oval varies in solar zenith angle due to the offset magnetic dipole), and season (greater values in the local winter hemisphere). Superposed on this well- behaved background structure are the complex, transient perturbations of auroral substorm and geomagnetic storm driven heating events at the high latitudes. These are more difficult to analyze, but are of great interest, as changes in neutral composition, for example, drive changes in ionospheric electron density. The current state of these efforts is to be presented.

Aquatic-macroinvertebrate communities of Prairie-Pothole wetlands and lakes under a changed climate

USGS Publications Warehouse

McLean, Kyle I.; Mushet, David M.; Renton, David A.; Stockwell, Craig A.

2016-01-01

Understanding how aquatic-macroinvertebrate communities respond to changes in climate is important for biodiversity conservation in the Prairie Pothole Region and other wetland-rich landscapes. We sampled macroinvertebrate communities of 162 wetlands and lakes previously sampled from 1966 to 1976, a much drier period compared to our 2012–2013 sampling timeframe. To identify possible influences of a changed climate and predation pressures on macroinvertebrates, we compared two predictors of aquatic-macroinvertebrate communities: ponded-water dissolved-ion concentration and vertebrate-predator presence/abundance. Further, we make inferences of how macroinvertebrate communities were structured during the drier period when the range of dissolved-ion concentrations was much greater and fish occurrence in aquatic habitats was rare. We found that aquatic-macroinvertebrate community structure was influenced by dissolved-ion concentrations through a complex combination of direct and indirect relationships. Ion concentrations also influenced predator occurrence and abundance, which indirectly affected macroinvertebrate communities. It is important to consider both abiotic and biotic gradients when predicting how invertebrate communities will respond to climate change. Generally, in the wetlands and lakes we studied, freshening of ponded water resulted in more homogenous communities than occurred during a much drier period when salinity range among sites was greater.

Mentat: An object-oriented macro data flow system

NASA Technical Reports Server (NTRS)

Grimshaw, Andrew S.; Liu, Jane W. S.

1988-01-01

Mentat, an object-oriented macro data flow system designed to facilitate parallelism in distributed systems, is presented. The macro data flow model is a model of computation similar to the data flow model with two principal differences: the computational complexity of the actors is much greater than in traditional data flow systems, and there are persistent actors that maintain state information between executions. Mentat is a system that combines the object-oriented programming paradigm and the macro data flow model of computation. Mentat programs use a dynamic structure called a future list to represent the future of computations.

Absence of first-order unbinding transitions of fluid and polymerized membranes

NASA Technical Reports Server (NTRS)

Grotehans, Stefan; Lipowsky, Reinhard

1990-01-01

Unbinding transitions of fluid and polymerized membranes are studied by renormalization-group (RG) methods. Two different RG schemes are used and found to give rather consistent results. The fixed-point structure of both RG's exhibits a complex behavior as a function of the decay exponent tau for the fluctuation-induced interaction of the membranes. For tau greater than tau(S2) interacting membranes can undergo first-order transitions even in the strong-fluctuation regime. These estimates for tau(S2) imply, however, that both fluid and polymerized membranes unbind in a continuous way in the absence of lateral tension.

Composition and structure of whey protein/gum arabic coacervates.

PubMed

Weinbreck, F; Tromp, R H; de Kruif, C G

2004-01-01

Complex coacervation in whey protein/gum arabic (WP/GA) mixtures was studied as a function of three main key parameters: pH, initial protein to polysaccharide mixing ratio (Pr:Ps)(ini), and ionic strength. Previous studies had already revealed under which conditions a coacervate phase was obtained. This study is aimed at understanding how these parameters influence the phase separation kinetics, the coacervate composition, and the internal coacervate structure. At a defined (Pr:Ps)(ini), an optimum pH of complex coacervation was found (pH(opt)), at which the strength of electrostatic interaction was maximum. For (Pr:Ps)(ini) = 2:1, the phase separation occurred the fastest and the final coacervate volume was the largest at pH(opt) = 4.0. The composition of the coacervate phase was determined after 48 h of phase separation and revealed that, at pH(opt), the coacervate phase was the most concentrated. Varying the (Pr:Ps)(ini) shifted the pH(opt) to higher values when (Pr:Ps)(ini) was increased and to lower values when (Pr:Ps)(ini) was decreased. This phenomenon was due to the level of charge compensation of the WP/GA complexes. Finally, the structure of the coacervate phase was studied with small-angle X-ray scattering (SAXS). SAXS data confirmed that at pH(opt) the coacervate phase was dense and structured. Model calculations revealed that the structure factor of WP induced a peak at Q = 0.7 nm(-1), illustrating that the coacervate phase was more structured, inducing the stronger correlation length of WP molecules. When the pH was changed to more acidic values, the correlation peak faded away, due to a more open structure of the coacervate. A shoulder in the scattering pattern of the coacervates was visible at small Q. This peak was attributed to the presence of residual charges on the GA. The peak intensity was reduced when the strength of interaction was increased, highlighting a greater charge compensation of the polyelectrolyte. Finally, increasing the ionic strength led to a less concentrated, a more heterogeneous, and a less structured coacervate phase, induced by the screening of the electrostatic interactions.

Non-ionizing real-time ultrasonography in implant and oral surgery: A feasibility study.

PubMed

Chan, Hsun-Liang; Wang, Hom-Lay; Fowlkes, Jeffery Brian; Giannobile, William V; Kripfgans, Oliver D

2017-03-01

Ultrasound imaging has potential to complement radiographic imaging modalities in implant and oral surgery given that it is non-ionizing and provides instantaneous images of anatomical structures. For application in oral and dental imaging, its qualities are dependent on its ability to accurately capture these complex structures. Therefore, the aim of this feasibility study was to investigate ultrasound to image soft tissue, hard tissue surface topography and specific vital structures. A clinical ultrasound scanner, paired with two 14-MHz transducers of different sizes (one for extraoral and the other for intraoral scans), was used to scan the following structures on a fresh cadaver: (i) the facial bone surface and soft tissue of maxillary anterior teeth, (ii) the greater palatine foramen; (iii) the mental foramen and (iv) the lingual nerve. Multiple measurements relevant to these structures were made on the ultrasound images and compared to those on cone-beam computed tomography (CBCT) scans and/or direct measurements. Ultrasound imaging could delineate hard tissue surfaces, including enamel, root dentin and bone as well as soft tissue with high resolution (110 μm wavelength). The greater palatine foramen, mental foramen and lingual nerve were clearly shown in ultrasound images. Merging ultrasound and CBCT images demonstrated overall spatial accuracy of ultrasound images, which was corroborated by data gathered from direct measurements. For the first time, this study provides proof-of-concept evidence that ultrasound can be a real-time and non-invasive alternative for the evaluation of oral and dental anatomical structures relevant for implant and oral surgery. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Retention of Habitat Complexity Minimizes Disassembly of Reef Fish Communities following Disturbance: A Large-Scale Natural Experiment

PubMed Central

Emslie, Michael J.; Cheal, Alistair J.; Johns, Kerryn A.

2014-01-01

High biodiversity ecosystems are commonly associated with complex habitats. Coral reefs are highly diverse ecosystems, but are under increasing pressure from numerous stressors, many of which reduce live coral cover and habitat complexity with concomitant effects on other organisms such as reef fishes. While previous studies have highlighted the importance of habitat complexity in structuring reef fish communities, they employed gradient or meta-analyses which lacked a controlled experimental design over broad spatial scales to explicitly separate the influence of live coral cover from overall habitat complexity. Here a natural experiment using a long term (20 year), spatially extensive (∼115,000 kms2) dataset from the Great Barrier Reef revealed the fundamental importance of overall habitat complexity for reef fishes. Reductions of both live coral cover and habitat complexity had substantial impacts on fish communities compared to relatively minor impacts after major reductions in coral cover but not habitat complexity. Where habitat complexity was substantially reduced, species abundances broadly declined and a far greater number of fish species were locally extirpated, including economically important fishes. This resulted in decreased species richness and a loss of diversity within functional groups. Our results suggest that the retention of habitat complexity following disturbances can ameliorate the impacts of coral declines on reef fishes, so preserving their capacity to perform important functional roles essential to reef resilience. These results add to a growing body of evidence about the importance of habitat complexity for reef fishes, and represent the first large-scale examination of this question on the Great Barrier Reef. PMID:25140801

Retention of habitat complexity minimizes disassembly of reef fish communities following disturbance: a large-scale natural experiment.

PubMed

Emslie, Michael J; Cheal, Alistair J; Johns, Kerryn A

2014-01-01

High biodiversity ecosystems are commonly associated with complex habitats. Coral reefs are highly diverse ecosystems, but are under increasing pressure from numerous stressors, many of which reduce live coral cover and habitat complexity with concomitant effects on other organisms such as reef fishes. While previous studies have highlighted the importance of habitat complexity in structuring reef fish communities, they employed gradient or meta-analyses which lacked a controlled experimental design over broad spatial scales to explicitly separate the influence of live coral cover from overall habitat complexity. Here a natural experiment using a long term (20 year), spatially extensive (∼ 115,000 kms(2)) dataset from the Great Barrier Reef revealed the fundamental importance of overall habitat complexity for reef fishes. Reductions of both live coral cover and habitat complexity had substantial impacts on fish communities compared to relatively minor impacts after major reductions in coral cover but not habitat complexity. Where habitat complexity was substantially reduced, species abundances broadly declined and a far greater number of fish species were locally extirpated, including economically important fishes. This resulted in decreased species richness and a loss of diversity within functional groups. Our results suggest that the retention of habitat complexity following disturbances can ameliorate the impacts of coral declines on reef fishes, so preserving their capacity to perform important functional roles essential to reef resilience. These results add to a growing body of evidence about the importance of habitat complexity for reef fishes, and represent the first large-scale examination of this question on the Great Barrier Reef.

Personal Risk and Resilience Factors in the Context of Daily Stress

PubMed Central

Diehl, Manfred; Hay, Elizabeth L.; Chui, Helena

2012-01-01

This chapter focuses on the role that personal risk and resilience factors play as adults of all ages cope with the stressors encountered in everyday life. Theorists have suggested that researchers should focus on the effects of daily stress and coping rather than focusing exclusively on major life events and chronic stress and have proposed that understanding how adults cope with daily stress is a key aspect of understanding long-term well-being and adaptation in adulthood. After presenting a conceptual model outlining the major components of the daily stress process, the chapter reviews the existing empirical literature on personal risk and resilience factors in the context of daily stress. This research clearly suggests that there is no universal generalization that can be made regarding whether chronological age, in and of itself, confers greater vulnerability or resilience onto adults. Instead, we argue that researchers should ask when and under what conditions is age associated with greater vulnerability to daily stress and when and under what conditions is age associated with greater resilience to daily stress. Age differences in reactivity to daily stress are clearly embedded within a complex system of factors—structural, individual, and situational—that influence stress reactivity and stress recovery in several ways. This complexity should not be taken to mean that stress reactivity and recovery cannot be charted or understood. Researchers, however, will need to approach this complexity with a great deal of theoretical, methodological, and statistical rigor to move our understanding of the importance of age in shaping risk and resilience to daily stress forward. The final section of the chapter outlines several directions for future research in the area of aging and resilience. In particular, we argue that a focus on personal risk and resilience factors in the context of daily stress, in combination with the application of sophisticated statistical methods (e.g., dynamic systems modeling), will contribute to a more dynamic and person-centered understanding of processes of resilience. PMID:23049156

Adaptive value of a predatory mouth-form in a dimorphic nematode

PubMed Central

Serobyan, Vahan; Ragsdale, Erik J.; Sommer, Ralf J.

2014-01-01

Polyphenisms can be adaptations to environments that are heterogeneous in space and time, but to persist they require conditional-specific advantages. The nematode Pristionchus pacificus is a facultative predator that displays an evolutionarily conserved polyphenism of its mouthparts. During development, P. pacificus irreversibly executes either a eurystomatous (Eu) or stenostomatous (St) mouth-form, which differ in the shape and number of movable teeth. The Eu form, which has an additional tooth, is more complex than the St form and is thus more highly derived relative to species lacking teeth. Here, we investigate a putative fitness trade-off for the alternative feeding-structures of P. pacificus. We show that the complex Eu form confers a greater ability to kill prey. When adults were provided with a prey diet, Eu nematodes exhibited greater fitness than St nematodes by several measures, including longevity, offspring survival and fecundity when followed by bacterial feeding. However, the two mouth-forms had similar fecundity when fed ad libitum on bacteria, a condition that would confer benefit on the more rapidly developing St form. Thus, the two forms show conditional fitness advantages in different environments. This study provides, to our knowledge, the first functional context for dimorphism in a model for the genetics of plasticity. PMID:25080344

Macroalgal Composition Determines the Structure of Benthic Assemblages Colonizing Fragmented Habitats.

PubMed

Matias, Miguel G; Arenas, Francisco; Rubal, Marcos; Pinto, Isabel S

2015-01-01

Understanding the consequences of fragmentation of coastal habitats is an important topic of discussion in marine ecology. Research on the effects of fragmentation has revealed complex and context-dependent biotic responses, which prevent generalizations across different habitats or study organisms. The effects of fragmentation in marine environments have been rarely investigated across heterogeneous habitats, since most studies have focused on a single type of habitat or patch. In this study, we assessed the effects of different levels of fragmentation (i.e. decreasing size of patches without overall habitat loss). We measured these effects using assemblages of macro-invertebrates colonizing representative morphological groups of intertidal macroalgae (e.g. encrusting, turf and canopy-forming algae). For this purpose, we constructed artificial assemblages with different combinations of morphological groups and increasing levels of fragmentation by manipulating the amount of bare rock or the spatial arrangement of different species in mixed assemblages. In general, our results showed that 1) fragmentation did not significantly affect the assemblages of macroinvertebrates; 2) at greater levels of fragmentation, there were greater numbers of species in mixed algal assemblages, suggesting that higher habitat complexity promotes species colonization. Our results suggest that predicting the consequences of fragmentation in heterogeneous habitats is dependent on the type and diversity of morphological groups making up those habitats.

Macroalgal Composition Determines the Structure of Benthic Assemblages Colonizing Fragmented Habitats

PubMed Central

Matias, Miguel G.; Arenas, Francisco; Rubal, Marcos; Pinto, Isabel S.

2015-01-01

Understanding the consequences of fragmentation of coastal habitats is an important topic of discussion in marine ecology. Research on the effects of fragmentation has revealed complex and context-dependent biotic responses, which prevent generalizations across different habitats or study organisms. The effects of fragmentation in marine environments have been rarely investigated across heterogeneous habitats, since most studies have focused on a single type of habitat or patch. In this study, we assessed the effects of different levels of fragmentation (i.e. decreasing size of patches without overall habitat loss). We measured these effects using assemblages of macro-invertebrates colonizing representative morphological groups of intertidal macroalgae (e.g. encrusting, turf and canopy-forming algae). For this purpose, we constructed artificial assemblages with different combinations of morphological groups and increasing levels of fragmentation by manipulating the amount of bare rock or the spatial arrangement of different species in mixed assemblages. In general, our results showed that 1) fragmentation did not significantly affect the assemblages of macroinvertebrates; 2) at greater levels of fragmentation, there were greater numbers of species in mixed algal assemblages, suggesting that higher habitat complexity promotes species colonization. Our results suggest that predicting the consequences of fragmentation in heterogeneous habitats is dependent on the type and diversity of morphological groups making up those habitats. PMID:26554924

Stage-structured infection transmission and a spatial epidemic: a model for Lyme disease.

PubMed

Caraco, Thomas; Glavanakov, Stephan; Chen, Gang; Flaherty, Joseph E; Ohsumi, Toshiro K; Szymanski, Boleslaw K

2002-09-01

A greater understanding of the rate at which emerging disease advances spatially has both ecological and applied significance. Analyzing the spread of vector-borne disease can be relatively complex when the vector's acquisition of a pathogen and subsequent transmission to a host occur in different life stages. A contemporary example is Lyme disease. A long-lived tick vector acquires infection during the larval blood meal and transmits it as a nymph. We present a reaction-diffusion model for the ecological dynamics governing the velocity of the current epidemic's spread. We find that the equilibrium density of infectious tick nymphs (hence the risk of human disease) can depend on density-independent survival interacting with biotic effects on the tick's stage structure. The local risk of infection reaches a maximum at an intermediate level of adult tick mortality and at an intermediate rate of juvenile tick attacks on mammalian hosts. If the juvenile tick attack rate is low, an increase generates both a greater density of infectious nymphs and an increased spatial velocity. However, if the juvenile attack rate is relatively high, nymph density may decline while the epidemic's velocity still increases. Velocities of simulated two-dimensional epidemics correlate with the model pathogen's basic reproductive number (R0), but calculating R0 involves parameters of both host infection dynamics and the vector's stage-structured dynamics.

Insights on the structural perturbations in human MTHFR Ala222Val mutant by protein modeling and molecular dynamics.

PubMed

Abhinand, P A; Shaikh, Faraz; Bhakat, Soumendranath; Radadiya, Ashish; Bhaskar, L V K S; Shah, Anamik; Ragunath, P K

2016-01-01

Methylenetetrahydrofolate reductase (MTHFR) protein catalyzes the only biochemical reaction which produces methyltetrahydrofolate, the active form of folic acid essential for several molecular functions. The Ala222Val polymorphism of human MTHFR encodes a thermolabile protein associated with increased risk of neural tube defects and cardiovascular disease. Experimental studies have shown that the mutation does not affect the kinetic properties of MTHFR, but inactivates the protein by increasing flavin adenine dinucleotide (FAD) loss. The lack of completely solved crystal structure of MTHFR is an impediment in understanding the structural perturbations caused by the Ala222Val mutation; computational modeling provides a suitable alternative. The three-dimensional structure of human MTHFR protein was obtained through homology modeling, by taking the MTHFR structures from Escherichia coli and Thermus thermophilus as templates. Subsequently, the modeled structure was docked with FAD using Glide, which revealed a very good binding affinity, authenticated by a Glide XP score of -10.3983 (kcal mol(-1)). The MTHFR was mutated by changing Alanine 222 to Valine. The wild-type MTHFR-FAD complex and the Ala222Val mutant MTHFR-FAD complex were subjected to molecular dynamics simulation over 50 ns period. The average difference in backbone root mean square deviation (RMSD) between wild and mutant variant was found to be ~.11 Å. The greater degree of fluctuations in the mutant protein translates to increased conformational stability as a result of mutation. The FAD-binding ability of the mutant MTHFR was also found to be significantly lowered as a result of decreased protein grip caused by increased conformational flexibility. The study provides insights into the Ala222Val mutation of human MTHFR that induces major conformational changes in the tertiary structure, causing a significant reduction in the FAD-binding affinity.

Solution 1H NMR investigation of the active site molecular and electronic structures of substrate-bound, cyanide-inhibited HmuO, a bacterial heme oxygenase from Corynebacterium diphtheriae.

PubMed

Li, Yiming; Syvitski, Ray T; Chu, Grace C; Ikeda-Saito, Masao; Mar, Gerd N La

2003-02-28

The molecular structure and dynamic properties of the active site environment of HmuO, a heme oxygenase (HO) from the pathogenic bacterium Corynebacterium diphtheriae, have been investigated by (1)H NMR spectroscopy using the human HO (hHO) complex as a homology model. It is demonstrated that not only the spatial contacts among residues and between residues and heme, but the magnetic axes that can be related to the direction and magnitude of the steric tilt of the FeCN unit are strongly conserved in the two HO complexes. The results indicate that very similar contributions of steric blockage of several meso positions and steric tilt of the attacking ligand are operative. A distal H-bond network that involves numerous very strong H-bonds and immobilized water molecules is identified in HmuO that is analogous to that previously identified in hHO (Li, Y., Syvitski, R. T., Auclair, K., Wilks, A., Ortiz de Montellano, P. R., and La Mar, G. N. (2002) J. Biol. Chem. 277, 33018-33031). The NMR results are completely consistent with the very recent crystal structure of the HmuO.substrate complex. The H-bond network/ordered water molecules are proposed to orient the distal water molecule near the catalytically key Asp(136) (Asp(140) in hHO) that stabilizes the hydroperoxy intermediate. The dynamic stability of this H-bond network in HmuO is significantly greater than in hHO and may account for the slower catalytic rate in bacterial HO compared with mammalian HO.

Masking effects of speech and music: does the masker's hierarchical structure matter?

PubMed

Shi, Lu-Feng; Law, Yvonne

2010-04-01

Speech and music are time-varying signals organized by parallel hierarchical rules. Through a series of four experiments, this study compared the masking effects of single-talker speech and instrumental music on speech perception while manipulating the complexity of hierarchical and temporal structures of the maskers. Listeners' word recognition was found to be similar between hierarchically intact and disrupted speech or classical music maskers (Experiment 1). When sentences served as the signal, significantly greater masking effects were observed with disrupted than intact speech or classical music maskers (Experiment 2), although not with jazz or serial music maskers, which differed from the classical music masker in their hierarchical structures (Experiment 3). Removing the classical music masker's temporal dynamics or partially restoring it affected listeners' sentence recognition; yet, differences in performance between intact and disrupted maskers remained robust (Experiment 4). Hence, the effect of structural expectancy was largely present across maskers when comparing them before and after their hierarchical structure was purposefully disrupted. This effect seemed to lend support to the auditory stream segregation theory.

A LEAST ABSOLUTE SHRINKAGE AND SELECTION OPERATOR (LASSO) FOR NONLINEAR SYSTEM IDENTIFICATION

NASA Technical Reports Server (NTRS)

Kukreja, Sunil L.; Lofberg, Johan; Brenner, Martin J.

2006-01-01

Identification of parametric nonlinear models involves estimating unknown parameters and detecting its underlying structure. Structure computation is concerned with selecting a subset of parameters to give a parsimonious description of the system which may afford greater insight into the functionality of the system or a simpler controller design. In this study, a least absolute shrinkage and selection operator (LASSO) technique is investigated for computing efficient model descriptions of nonlinear systems. The LASSO minimises the residual sum of squares by the addition of a 1 penalty term on the parameter vector of the traditional 2 minimisation problem. Its use for structure detection is a natural extension of this constrained minimisation approach to pseudolinear regression problems which produces some model parameters that are exactly zero and, therefore, yields a parsimonious system description. The performance of this LASSO structure detection method was evaluated by using it to estimate the structure of a nonlinear polynomial model. Applicability of the method to more complex systems such as those encountered in aerospace applications was shown by identifying a parsimonious system description of the F/A-18 Active Aeroelastic Wing using flight test data.

Greater Engagement Among Members of Gay-Straight Alliances: Individual and Structural Contributors

PubMed Central

Poteat, V. Paul; Heck, Nicholas C.; Yoshikawa, Hirokazu; Calzo, Jerel P.

2017-01-01

Using youth program models to frame the study of Gay-Straight Alliances (GSAs), we identified individual and structural predictors of greater engagement in these settings with a cross-sectional sample of 295 youth in 33 GSAs from the 2014 Massachusetts GSA Network Survey (69% LGBQ, 68% cisgen-der female, 68% White, Mage = 16.07). Multilevel modeling results indicated that members who perceived more support/socializing from their GSA, had more LGB friends, were longer serving members, and were in GSAs with more open and respectful climates reported greater engagement. Further, there was a curvilinear association between organizational structure in the GSA and engagement: Perceptions of more structure were associated with greater engagement to a point, after which greater structure was related to less engagement. PMID:28757649

The influence of species, density, and diversity of macroalgal aggregations on microphytobenthic settlement.

PubMed

Umanzor, Schery; Ladah, Lydia; Zertuche-González, José A

2017-10-01

Intertidal macroalgae can modulate their biophysical environment by ameliorating physical conditions and creating habitats. Exploring how seaweed aggregations made up of different species at different densities modify the local environment may help explain how associated organisms respond to the attenuation of extreme physical conditions. Using Silvetia compressa, Chondracanthus canaliculatus, and Pyropia perforata, we constructed monocultures representing the leathery, corticated and foliose functional forms as well as a mixed tri-culture assemblage including the former three, at four densities. Treatment quadrats were installed in the intertidal where we measured irradiance, temperature, particle retention, and water motion underneath the canopies. Additionally, we examined the abundance and richness of the understory microphytobenthos with settlement slides. We found that the density and species composition of the assemblages modulated the amelioration of extreme physical conditions, with macroalgal aggregations of greater structural complexity due to their form and density showing greater physical factor attenuation. However, increasing the number of species within a patch did not directly result in increased complexity and therefore, did not necessarily cause greater amelioration of the environment. Microphytobenthic composition was also affected by species composition and density, with higher abundances under S. compressa and C. canaliculatus canopies at high and mid densities. These results support the idea that the environmental modifications driven by these macroalgae have a significant effect on the dynamics of the intertidal environment by promoting distinct temporal and spatial patchiness in the microphytobenthos, with potentially significant effects on the overall productivity of these ecosystems. © 2017 Phycological Society of America.

The conception of administrators regarding the formation of a healthcare consortium in Pernambuco, Brazil: a case study.

PubMed

e Silva, Keila S Brito; Bezerra, Adriana Falangola B

2011-01-01

The formation of healthcare consortia is a management strategy adopted by a number of cities in Brazil in order to minimize the difficulties the population has in access to services of greater technological complexity. As administrators are the main governmental actors in the promotion of this strategy, the aim of the present study was to identify the motives, expectations and difficulties faced by the mayors, and secretaries of health that make up a healthcare consortium undergoing a formation process in the rural, coastal zone of the state of Pernambuco. A descriptive, qualitative, case study was conducted. Data collection was carried out through semi-structured interviews held with mayors and secretaries of health of the municipalities participating in the consortium. Data were analyzed by means of content analysis, using the NVivo 2.0 software program. The administrators cited difficulty in access to specialized services and the high cost of transporting patients to distant locations for treatment as motives for the formation of the consortium. With the implantation of this healthcare strategy, the expectations are a reduction in costs regarding patient transportation, an increase in access to services of greater complexity, and negotiations with other spheres of government. The main difficulties faced are political-partisan conflicts and excessive bureaucracy. Although there were no considerable divergences in the administrators' perceptions, it was evident that those who initiated the formation of the consortium offered a deeper, more detailed discourse, thereby demonstrating greater involvement when compared to those who offered continuity to the process. Copyright © 2010 John Wiley & Sons, Ltd.

Synthetic humic substances and their use for remediation of contaminated environments

NASA Astrophysics Data System (ADS)

Dudare, Diana; Klavins, Maris

2014-05-01

Soils are increasingly subjected to different chemical stresses, because of increasing industrialization process and other factors. Different anthropogenic compounds (organic or inorganic in nature) upon entering the soil, may not only influence its productivity potential, but may also affect the quality of groundwater and food chain. Consequently, soils of different environments contain a complex mixture of contaminants, such as oil products, metals, organic solvents, acids, bases and radionuclides. Thereby greater focus should be paid to risk assessment and evaluation of remedial techniques in order to restore the quality of the soil and groundwater. The treatment technologies presently used to remove contaminants are physical, chemical and biological technologies. Many functional groups in the structure of humic substances determine their ability to interact with metal ions forming stable complexes and influencing speciation of metal ions in the environment, as well mobility, behaviour and speciation forms in the environment. Humic substances are suggested for use in the remediation of environments contaminated with metals, owing to complex forming properties. Several efforts have been undertaken with respect to synthesize humic substances for their structural studies. At the same time the real number of methods suggested for synthesis of humic substances is highly limited and their synthesis in general has been used mostly for their structural analysis. The present study deals with development of approaches for synthesis of humic substances with increased complex forming ability in respect to metal ions. Industrially produced humic substances (TEHUM) were used for comparison and after their modification their properties were analyzed for their elemental composition; functional group content changes in spectral characteristics. Synthetic humic substances showed significant differences in the number of functional groups and in ability to interact with the metal ions, which were reflected in their complexation properties towards metal ions. FTIR spectra gave evidence of the presence of metal ions, strongly bound and protected in inner sphere complexes. Considering a large scale of production of humic substances, the obtained synthetic humic substances with modified properties are perspective and sustainable areas of use. The obtained results of this study showed that synthetic humic substances can be used for remediation of environments contaminated with heavy metal ions.

Macroscopic and microscopic analysis of the thumb carpometacarpal ligaments: a cadaveric study of ligament anatomy and histology.

PubMed

Ladd, Amy L; Lee, Julia; Hagert, Elisabet

2012-08-15

Stability and mobility represent the paradoxical demands of the human thumb carpometacarpal joint, yet the structural origin of each functional demand is poorly defined. As many as sixteen and as few as four ligaments have been described as primary stabilizers, but controversy exists as to which ligaments are most important. We hypothesized that a comparative macroscopic and microscopic analysis of the ligaments of the thumb carpometacarpal joint would further define their role in joint stability. Thirty cadaveric hands (ten fresh-frozen and twenty embalmed) from nineteen cadavers (eight female and eleven male; average age at the time of death, seventy-six years) were dissected, and the supporting ligaments of the thumb carpometacarpal joint were identified. Ligament width, length, and thickness were recorded for morphometric analysis and were compared with use of the Student t test. The dorsal and volar ligaments were excised from the fresh-frozen specimens and were stained with use of a triple-staining immunofluorescent technique and underwent semiquantitative analysis of sensory innervation; half of these specimens were additionally analyzed for histomorphometric data. Mixed-effects linear regression was used to estimate differences between ligaments. Seven principal ligaments of the thumb carpometacarpal joint were identified: three dorsal deltoid-shaped ligaments (dorsal radial, dorsal central, posterior oblique), two volar ligaments (anterior oblique and ulnar collateral), and two ulnar ligaments (dorsal trapeziometacarpal and intermetacarpal). The dorsal ligaments were significantly thicker (p < 0.001) than the volar ligaments, with a significantly greater cellularity and greater sensory innervation compared with the anterior oblique ligament (p < 0.001). The anterior oblique ligament was consistently a thin structure with a histologic appearance of capsular tissue with low cellularity. The dorsal deltoid ligament complex is uniformly stout and robust; this ligament complex is the thickest morphometrically, has the highest cellularity histologically, and shows the greatest degree of sensory nerve endings. The hypocellular anterior oblique ligament is thin, is variable in its location, and is more structurally consistent with a capsular structure than a proper ligament.

Metamorphic and tectonic evolution of the Greater Himalayan Crystalline Complex in Nyalam region, south Tibet

NASA Astrophysics Data System (ADS)

Wang, Jia-Min; Zhang, Jin-Jiang; Rubatto, Daniela

2016-04-01

Recent studies evoke dispute whether the Himalayan metamorphic core - Greater Himalayan Crystalline Complex (GHC) - was exhumed as a lateral crustal flow or a critical taper wedge during the India-Asia collision. This contribution investigated the evolution of the GHC in the Nyalam region, south Tibet, with comprehensive studies on structural kinematics, metamorphic petrology and geochronology. The GHC in the Nyalam region can be divided into the lower and upper GHC. Phase equilibria modelling and conventional thermobarometric results show that peak temperature conditions are lower in the lower GHC (~660-700°C) and higher in the upper GHC (~740-780°C), whereas corresponding pressure conditions at peak-T decrease from ~9-13 kbar to ~4 kbar northward. Monazite, zircon and rutile U-Pb dating results reveal two distinct blocks within the GHC of the Nyalam region. The upper GHC underwent higher degree of partial melting (15-25%, via muscovite dehydration melting) that initiated at ~32 Ma, peaked at ~29 Ma to 25 Ma, possibly ended at ~20 Ma. The lower GHC underwent lower degree of melting (0-10%) that lasted from 19 to 16 Ma, which was produced mainly via H2O-saturated melting. At different times, both the upper and lower blocks underwent initial slow cooling (35 ± 8 and 10 ± 5°C/Myr, respectively) and subsequent rapid cooling (120 ± 40°C/Myr). The established timescale of metamorphism suggests that high-temperature metamorphism within the GHC lasted a long duration (~15 Myr), whereas duration of partial melting lasted for ~3 Myr in the lower GHC and lasted for 7-12 Myr in the upper GHC. The documented diachronous metamorphism and discontinuity of peak P-T conditions implies the presence of the Nyalam Thrust in the study area. This thrust is probably connected to the other thrusts in Nepal and Sikkim Himalaya, which extends over ~800 km and is named the "High Himalayan Thrust". Timing of activity along this thrust is at ~25-16 Ma, which is coeval with active timing along the South Tibetan detachment (27-16 Ma) but precedes that along the MCT (16-10 Ma). Comparison between the obtained P-T-t data and model predictions implies that a lateral crustal flow process dominated the exhumation of the high-grade upper GHC migmitites during 25-16 Ma, whereas a critical taper thrusting process dominated the exhumation of the MCT zone nonmigmatites and cooled migmatites in the lower GHC at 16-10 Ma. In other words, at different temporal and spatial scale, both propagating thrusting along large tectonic boundaries and a low-viscosity melting crust could contribute to the exhumation of high-grade metamorphic rocks in Himalaya-like large hot collisional orogens. KEY WORDS: Greater Himalayan Crystalline Complex; P-T path; U-Pb geochronology; channel flow; tectonic discontinuity References: Wang, J.M., Rubatto, D., Zhang, J.J., 2015a. Timing of partial melting and cooling across the Greater Himalayan Crystalline Complex (Nyalam, central Himalaya): in-sequence thrusting and its implications. Journal of Petrology, 56, 1677-1702. Wang, J.M., Zhang, J.J., Wei, C.J., Rai, S.M., Wang, M., Qian, J.H., 2015b. Characterizing the metamorphic discontinuity across the Main Central Thrust Zone of eastern-central Nepal. Journal of Asian Earth Sciences 101, 83-100. Wang, J.M., Zhang, J.J., Wang, X.X., 2013. Structural kinematics, metamorphic P-T profiles and zircon geochronology across the Greater Himalayan Crystalline Complex in south-central Tibet: implication for a revised channel flow. Journal of Metamorphic Geology 31, 607-628.

A novel method of naturally contouring the reconstructed ear: modified antihelix complex affixed to grooved base frame.

PubMed

Li, Datao; Zhang, Ruhong; Zhang, Qun; Xu, Zhicheng; Xu, Feng; Li, Yiyuan; Sun, Nan; Wang, Cheng

2014-05-01

Prior reports of ear reconstruction have cited favorable results. Although greater attention has been devoted to fabricating a more refined cartilaginous framework, many patients still complain that the contours are unnatural. The authors' aim was to offer a new technique that resolves some lingering issues. To fabricate the antihelix complex optimally, the authors modified an existing method. Rather than chiseling a sharp, Y-shaped graft of cartilage for structural prominence, the superior crus is broadened, and a gentle slope is sculpted on both aspects. Simultaneously, a groove in the base frame is carved for smooth attachment. The width of the inferior crus is limited to roughly one-third that of the superior crus, and the inferior crus is maintained in high relief. A gentle slope is shaped on the antihelix, and a groove for placement of the antihelix is carved into the base frame. Between 2011 and 2013, a total of 162 patients underwent reconstruction using this modified technique. Three such subjects have been selected to highlight the favorable results achieved. Given modifications confer natural contours to superior and inferior crura, antihelix, and surrounding structures, providing a cohesive framework for the integrity of a reconstructed ear. The antihelix complex is critical for creating a natural auricle. Harmonious integration of superior and inferior crura and antihelix enhances the overall aesthetics, increasing procedural satisfaction for patient and surgeon alike. Therapeutic, IV.

Visual detection of nucleic acids based on Mie scattering and the magnetophoretic effect.

PubMed

Zhao, Zichen; Chen, Shan; Ho, John Kin Lim; Chieng, Ching-Chang; Chen, Ting-Hsuan

2015-12-07

Visual detection of nucleic acid biomarkers is a simple and convenient approach to point-of-care applications. However, issues of sensitivity and the handling of complex bio-fluids have posed challenges. Here we report on a visual method detecting nucleic acids using Mie scattering of polystyrene microparticles and the magnetophoretic effect. Magnetic microparticles (MMPs) and polystyrene microparticles (PMPs) were surface-functionalised with oligonucleotide probes, which can hybridise with target oligonucleotides in juxtaposition and lead to the formation of MMPs-targets-PMPs sandwich structures. Using an externally applied magnetic field, the magnetophoretic effect attracts the sandwich structure to the sidewall, which reduces the suspended PMPs and leads to a change in the light transmission via the Mie scattering. Based on the high extinction coefficient of the Mie scattering (∼3 orders of magnitude greater than that of the commonly used gold nanoparticles), our results showed the limit of detection to be 4 pM using a UV-Vis spectrometer or 10 pM by direct visual inspection. Meanwhile, we also demonstrated that this method is compatible with multiplex assays and detection in complex bio-fluids, such as whole blood or a pool of nucleic acids, without purification in advance. With a simplified operation procedure, low instrumentation requirement, high sensitivity and compatibility with complex bio-fluids, this method provides an ideal solution for visual detection of nucleic acids in resource-limited settings.

Seismotectonic zoning of Azerbaijan territory

NASA Astrophysics Data System (ADS)

Kangarli, Talat; Aliyev, Ali; Aliyev, Fuad; Rahimov, Fuad

2017-04-01

Studying of the space-time correlation and consequences effect between tectonic events and other geological processes that have created modern earth structure still remains as one of the most important problems in geology. This problem is especially important for the East Caucasus-South Caspian geodynamic zone. Being situated at the eastern part of the Caucasian strait, this zone refers to a center of Alpine-Himalayan active folded belt, and is known as a complex tectonic unit with jointing heterogeneous structural-substantial complexes arising from different branches of the belt (Doburja-Caucasus-Kopetdag from the north and Pyrenean-Alborz from the south with Kura and South Caspian zone). According to GPS and precise leveling data, activity of regional geodynamic processes shows intensive horizontal and vertical movements of the Earth's crust as conditioned by collision of the Arabian and Eurasian continental plates continuing since the end of Miocene. So far studies related to the regional of geology-geophysical data, periodically used for the geological and tectonic modeling of the environment mainly based on the fixing ideology. There still remains a number of uncertainties in solution of issues related to regional geology, tectonics and magmatism, structure and interrelation of different structural zones, space-time interrelations between onshore and offshore complexes, etc. At the same time large dataset produced by surface geological surveys, deep geological mapping of on- and offshore areas with the use of seismic and electrical reconnaissance and geophysical field zoning methods, deep well drilling and remote sensing activities. Conducted new studies produced results including differentiation of formerly unknown nappe complexes of the different ages and scales within the structure of mountain-fold zones, identification of new zones containing ophiolites in their section, outlining of currently active faulting areas, geophysical interpretation of the deep structure of Greater and Lesser Caucasus, detailed description of the deep structure of Caspian zone, Kur and Caspian megadepressions, identification of nappe-folded structure of the Absheron Peninsula and the Absheron threshold at the border of Middle and South Caspian, justification of the possible hydrocarbon concentration at the tectonically stratified substantial complexes of mountain and foothill areas, etc. Based on the outcomes of implemented researches, some general conclusions and schemes were drawn for some parts of the project region within the plate tectonics conceptual frameworks, to include the territories of Lesser Caucasus and South Caspian. Analysis and comparison of these data with macroseismic and instrumental data allowed us to conduct seismotectonic studies in a region and develop a new scheme of seismotectonic map with outlined recent and forecasted seismic activity. There also correlated foci zones of earthquakes with subhorizontal and subvertical borders in earth crust, which shows their structure-dynamic relationship. In the one hand, the earthquake foci zones belong to the faults of the basement which extend to sedimentary cover and their intersection knots. On the other hand, there appearing inner-block seismogenic levels, namely, in seismic generation acts all the earth crust: tectonic stress results on movements along fault zones, as well as lateral displacements along non-stable contacts of the structure-substance complexes of different competency.

Flying between sky islands: the effect of naturally fragmented habitat on butterfly population structure.

PubMed

Sekar, Sandhya; Karanth, Praveen

2013-01-01

High elevation montane areas are called "sky islands" when they occur as a series of high mountains separated by lowland valleys. Different climatic conditions at high elevations makes sky islands a specialized type of habitat, rendering them naturally fragmented compared to more continuous habitat at lower elevations. Species in sky islands face unsuitable climate in the intervening valleys when moving from one montane area to another. The high elevation shola-grassland mosaic in the Western Ghats of southern India form one such sky island complex. The fragmented patches make this area ideal to study the effect of the spatial orientation of suitable habitat patches on population genetic structure of species found in these areas. Past studies have suggested that sky islands tend to have genetically structured populations, possibly due to reduced gene flow between montane areas. To test this hypothesis, we adopted the comparative approach. Using Amplified Fragment Length Polymorphisms, we compared population genetic structures of two closely related, similar sized butterfly species: Heteropsis oculus, a high elevation shola-grassland specialist restricted to the southern Western Ghats, and Mycalesis patnia, found more continuously distributed in lower elevations. In all analyses, as per expectation the sky island specialist H. oculus exhibited a greater degree of population genetic structure than M. patnia, implying a difference in geneflow. This difference in geneflow in turn appears to be due to the natural fragmentation of the sky island complexes. Detailed analysis of a subset of H. oculus samples from one sky island complex (the Anamalais) showed a surprising genetic break. A possible reason for this break could be unsuitable conditions of higher temperature and lower rainfall in the intervening valley region. Thus, sky island species are not only restricted by lack of habitat continuity between montane areas, but also by the nature of the intervening habitat.

Canopy structural complexity influences forest canopy reflectance: linking terrestrial lidar with Landsat observations

NASA Astrophysics Data System (ADS)

Hardiman, B. S.; Atkins, J.; Dahlin, K.; Fahey, R. T.; Gough, C. M.

2016-12-01

Canopy physical structure - leaf quantity and arrangement - strongly affects light interception and distribution. As such, canopy physical structure is a key driver of forest carbon (C) dynamics. Terrestrial lidar systems (TLS) provide spatially explicit, quantitative characterizations of canopy physical structure at scales commensurate with plot-scale C cycling processes. As an example, previous TLS-based studies established that light use efficiency is positively correlated with canopy physical structure, influencing the trajectory of net primary production throughout forest development. Linking TLS measurements of canopy structure to multispectral satellite observations of forest canopies may enable scaling of ecosystem C cycling processes from leaves to continents. We will report on our study relating a suite of canopy structural metrics to well-established remotely sensed measurements (NDVI, EVI, albedo, tasseled cap indices, etc.) which are indicative of important forest characteristics (leaf area, canopy nitrogen, light interception, etc.). We used Landsat data, which provides observations at 30m resolution, a scale comparable to that of TLS. TLS data were acquired during 2009-2016 from forest sites throughout Eastern North America, comprised primarily of NEON and Ameriflux sites. Canopy physical structure data were compared with contemporaneous growing-season Landsat data. Metrics of canopy physical structure are expected to covary with forest composition and dominant PFT, likely influencing interaction strength between TLS and Landsat canopy metrics. More structurally complex canopies (those with more heterogeneous distributions of leaf area) are expected to have lower albedo, suggesting greater canopy light absorption (higher fAPAR) than simpler canopies. We expect that vegetation indices (NDVI, EVI) will increase with TLS metrics of spatial heterogeneity, and not simply quantity, of leaves, supporting our hypothesis that canopy light absorption is dependent on both leaf quantity and arrangement. Relating satellite observations of canopy properties to TLS metrics of canopy physical structure represents an important advance for modelling canopy energy balance and forest C cycling processes at large spatial scales.

Artificial nest predation in hedgerows and scrub forest in a human-dominated landscape of central Mexico

NASA Astrophysics Data System (ADS)

Zuria, Iriana; Gates, J. Edward; Castellanos, Ignacio

2007-03-01

Hedgerows as well as other narrow corridors could be valuable habitats for birds in regions of intensive agriculture, however, it is still not clear how successful breeding birds are in different types of hedgerows as compared to birds nesting in their natural habitats. We used artificial nests to examine whether hedgerows were sinks (ecological traps) for birds by comparing rates of predation in two types of hedgerows with different vegetation structure (simple and complex), and in a tract of scrub forest in an agricultural landscape of central Mexico. We determined also the types of predators responsible for egg predation. Ground and elevated nests were baited with one Japanese quail Coturnix japonica egg and one plasticine egg and placed alternately along transects. Significantly, greater predation rates were found in scrub forest and complex hedgerows than in simple hedgerows. Higher predation rates in complex habitats seemed to reflect the higher number of predator types found there. The most important predator types were carnivores followed by rodents, birds, and humans. Carnivores and rodents mainly predated ground nests, whereas birds and humans predated elevated nests. Simple hedgerows in this landscape appeared to offer relatively safe nest sites in terms of predation pressure when compared to more complex habitats (complex hedgerows and scrub forest).

Convergent and Divergent fMRI Responses in Children and Adults to Increasing Language Production Demands

PubMed Central

Krishnan, Saloni; Leech, Robert; Mercure, Evelyne; Lloyd-Fox, Sarah; Dick, Frederic

2015-01-01

In adults, patterns of neural activation associated with perhaps the most basic language skill—overt object naming—are extensively modulated by the psycholinguistic and visual complexity of the stimuli. Do children's brains react similarly when confronted with increasing processing demands, or they solve this problem in a different way? Here we scanned 37 children aged 7–13 and 19 young adults who performed a well-normed picture-naming task with 3 levels of difficulty. While neural organization for naming was largely similar in childhood and adulthood, adults had greater activation in all naming conditions over inferior temporal gyri and superior temporal gyri/supramarginal gyri. Manipulating naming complexity affected adults and children quite differently: neural activation, especially over the dorsolateral prefrontal cortex, showed complexity-dependent increases in adults, but complexity-dependent decreases in children. These represent fundamentally different responses to the linguistic and conceptual challenges of a simple naming task that makes no demands on literacy or metalinguistics. We discuss how these neural differences might result from different cognitive strategies used by adults and children during lexical retrieval/production as well as developmental changes in brain structure and functional connectivity. PMID:24907249

Plant metabolic modeling: achieving new insight into metabolism and metabolic engineering.

PubMed

Baghalian, Kambiz; Hajirezaei, Mohammad-Reza; Schreiber, Falk

2014-10-01

Models are used to represent aspects of the real world for specific purposes, and mathematical models have opened up new approaches in studying the behavior and complexity of biological systems. However, modeling is often time-consuming and requires significant computational resources for data development, data analysis, and simulation. Computational modeling has been successfully applied as an aid for metabolic engineering in microorganisms. But such model-based approaches have only recently been extended to plant metabolic engineering, mainly due to greater pathway complexity in plants and their highly compartmentalized cellular structure. Recent progress in plant systems biology and bioinformatics has begun to disentangle this complexity and facilitate the creation of efficient plant metabolic models. This review highlights several aspects of plant metabolic modeling in the context of understanding, predicting and modifying complex plant metabolism. We discuss opportunities for engineering photosynthetic carbon metabolism, sucrose synthesis, and the tricarboxylic acid cycle in leaves and oil synthesis in seeds and the application of metabolic modeling to the study of plant acclimation to the environment. The aim of the review is to offer a current perspective for plant biologists without requiring specialized knowledge of bioinformatics or systems biology. © 2014 American Society of Plant Biologists. All rights reserved.

Plant Metabolic Modeling: Achieving New Insight into Metabolism and Metabolic Engineering

PubMed Central

Baghalian, Kambiz; Hajirezaei, Mohammad-Reza; Schreiber, Falk

2014-01-01

Models are used to represent aspects of the real world for specific purposes, and mathematical models have opened up new approaches in studying the behavior and complexity of biological systems. However, modeling is often time-consuming and requires significant computational resources for data development, data analysis, and simulation. Computational modeling has been successfully applied as an aid for metabolic engineering in microorganisms. But such model-based approaches have only recently been extended to plant metabolic engineering, mainly due to greater pathway complexity in plants and their highly compartmentalized cellular structure. Recent progress in plant systems biology and bioinformatics has begun to disentangle this complexity and facilitate the creation of efficient plant metabolic models. This review highlights several aspects of plant metabolic modeling in the context of understanding, predicting and modifying complex plant metabolism. We discuss opportunities for engineering photosynthetic carbon metabolism, sucrose synthesis, and the tricarboxylic acid cycle in leaves and oil synthesis in seeds and the application of metabolic modeling to the study of plant acclimation to the environment. The aim of the review is to offer a current perspective for plant biologists without requiring specialized knowledge of bioinformatics or systems biology. PMID:25344492

A novel L-ficolin/mannose-binding lectin chimeric molecule with enhanced activity against Ebola virus.

PubMed

Michelow, Ian C; Dong, Mingdong; Mungall, Bruce A; Yantosca, L Michael; Lear, Calli; Ji, Xin; Karpel, Marshall; Rootes, Christina L; Brudner, Matthew; Houen, Gunnar; Eisen, Damon P; Kinane, T Bernard; Takahashi, Kazue; Stahl, Gregory L; Olinger, Gene G; Spear, Gregory T; Ezekowitz, R Alan B; Schmidt, Emmett V

2010-08-06

Ebola viruses constitute a newly emerging public threat because they cause rapidly fatal hemorrhagic fevers for which no treatment exists, and they can be manipulated as bioweapons. We targeted conserved N-glycosylated carbohydrate ligands on viral envelope surfaces using novel immune therapies. Mannose-binding lectin (MBL) and L-ficolin (L-FCN) were selected because they function as opsonins and activate complement. Given that MBL has a complex quaternary structure unsuitable for large scale cost-effective production, we sought to develop a less complex chimeric fusion protein with similar ligand recognition and enhanced effector functions. We tested recombinant human MBL and three L-FCN/MBL variants that contained the MBL carbohydrate recognition domain and varying lengths of the L-FCN collagenous domain. Non-reduced chimeric proteins formed predominantly nona- and dodecameric oligomers, whereas recombinant human MBL formed octadecameric and larger oligomers. Surface plasmon resonance revealed that L-FCN/MBL76 had the highest binding affinities for N-acetylglucosamine-bovine serum albumin and mannan. The same chimeric protein displayed superior complement C4 cleavage and binding to calreticulin (cC1qR), a putative receptor for MBL. L-FCN/MBL76 reduced infection by wild type Ebola virus Zaire significantly greater than the other molecules. Tapping mode atomic force microscopy revealed that L-FCN/MBL76 was significantly less tall than the other molecules despite similar polypeptide lengths. We propose that alterations in the quaternary structure of L-FCN/MBL76 resulted in greater flexibility in the collagenous or neck region. Similarly, a more pliable molecule might enhance cooperativity between the carbohydrate recognition domains and their cognate ligands, complement activation, and calreticulin binding dynamics. L-FCN/MBL chimeric proteins should be considered as potential novel therapeutics.

Optimal trajectories of brain state transitions

PubMed Central

Gu, Shi; Betzel, Richard F.; Mattar, Marcelo G.; Cieslak, Matthew; Delio, Philip R.; Grafton, Scott T.; Pasqualetti, Fabio; Bassett, Danielle S.

2017-01-01

The complexity of neural dynamics stems in part from the complexity of the underlying anatomy. Yet how white matter structure constrains how the brain transitions from one cognitive state to another remains unknown. Here we address this question by drawing on recent advances in network control theory to model the underlying mechanisms of brain state transitions as elicited by the collective control of region sets. We find that previously identified attention and executive control systems are poised to affect a broad array of state transitions that cannot easily be classified by traditional engineering-based notions of control. This theoretical versatility comes with a vulnerability to injury. In patients with mild traumatic brain injury, we observe a loss of specificity in putative control processes, suggesting greater susceptibility to neurophysiological noise. These results offer fundamental insights into the mechanisms driving brain state transitions in healthy cognition and their alteration following injury. PMID:28088484

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyers, D.; Liu, Jian; Freeland, J. W.

We observed complex materials in electronic phases and transitions between them often involve coupling between many degrees of freedom whose entanglement convolutes understanding of the instigating mechanism. Metal-insulator transitions are one such problem where coupling to the structural, orbital, charge, and magnetic order parameters frequently obscures the underlying physics. We demonstrate a way to unravel this conundrum by heterostructuring a prototypical multi-ordered complex oxide NdNiO3 in ultra thin geometry, which preserves the metal-to-insulator transition and bulk-like magnetic order parameter, but entirely suppresses the symmetry lowering and long-range charge order parameter. Furthermore, these findings illustrate the utility of heterointerfaces as amore » powerful method for removing competing order parameters to gain greater insight into the nature of the transition, here revealing that the magnetic order generates the transition independently, leading to an exceptionally rare purely electronic metal-insulator transition with no symmetry change.« less

Development and characterisation of a novel three-dimensional inter-kingdom wound biofilm model.

PubMed

Townsend, Eleanor M; Sherry, Leighann; Rajendran, Ranjith; Hansom, Donald; Butcher, John; Mackay, William G; Williams, Craig; Ramage, Gordon

2016-11-01

Chronic diabetic foot ulcers are frequently colonised and infected by polymicrobial biofilms that ultimately prevent healing. This study aimed to create a novel in vitro inter-kingdom wound biofilm model on complex hydrogel-based cellulose substrata to test commonly used topical wound treatments. Inter-kingdom triadic biofilms composed of Candida albicans, Pseudomonas aeruginosa, and Staphylococcus aureus were shown to be quantitatively greater in this model compared to a simple substratum when assessed by conventional culture, metabolic dye and live dead qPCR. These biofilms were both structurally complex and compositionally dynamic in response to topical therapy, so when treated with either chlorhexidine or povidone iodine, principal component analysis revealed that the 3-D cellulose model was minimally impacted compared to the simple substratum model. This study highlights the importance of biofilm substratum and inclusion of relevant polymicrobial and inter-kingdom components, as these impact penetration and efficacy of topical antiseptics.

Protein-protein recognition: crystal structural analysis of a barnase-barstar complex at 2.0-A resolution.

PubMed

Buckle, A M; Schreiber, G; Fersht, A R

1994-08-02

We have solved, refined, and analyzed the 2.0-å resolution crystal structure of a 1:1 complex between the bacterial ribonuclease, barnase, and a Cys-->Ala(40,82) double mutant of its intracellular polypeptide inhibitor, barstar. Barstar inhibits barnase by sterically blocking the active site with a helix and adjacent loop segment. Almost half of the 14 hydrogen bonds between barnase and barstar involve two charged residues, and a third involve one charged partner. The electrostatic contribution to the overall binding energy is considerably greater than for other protein-protein interactions. Consequently, the very high rate constant for the barnase-barstar association (10(8) s-1 M-1) is most likely due to electrostatic steering effects. The barnase active-site residue His102 is located in a pocket on the surface of barstar, and its hydrogen bonds with Asp39 and Gly31 residues of barstar are directly responsible for the pH dependence of barnase-barstar binding. There is a high degree of complementarity both of the shape and of the charge of the interacting surfaces, but neither is perfect. The surface complementarity is slightly poorer than in protease-inhibitor complexes but a little better than in antibody-antigen interactions. However, since the burial of solvent in the barnase-barstar interface improves the fit significantly by filling in the majority of gaps, as well as stabilizing unfavorable electrostatic interactions, its role seems to be more important than in other protein-protein complexes. The electrostatic interactions between barnase and barstar are very similar to those between barnase and the tetranucleotide d(CGAC). In the barnase-barstar complex, the two phosphate-binding sites in the barnase active site are occupied by Asp39 and Gly43 of barstar. However, barstar has no equivalent for a guanine base of an RNA substrate, resulting in the occupation of the guanine recognition site in the barnase-barstar complex by nine ordered water molecules. Upon barnase-barstar binding, entropy losses resulting from the immobilization of segments of the protein chain and the energetic costs of conformational changes are minimized due to the essentially preformed active site of barnase. However, a certain degree of flexibility within the barnase active site is required to allow for the structural differences between barnase-barstar binding and barnase-RNA binding. A comparison between the bound and the free barstar structure shows that the overall structural response to barnase-binding is significant. This response can be best described as outwardly oriented, rigid-body movements of the four alpha-helices of barstar, resulting in the structure of bound barstar being somewhat expanded.

Lithospheric Velocity Structure of the Anatolain plateau-Caucasus-Caspian Regions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gok, R; Mellors, R J; Sandvol, E

Anatolian Plateau-Caucasus-Caspian region is an area of complex structure accompanied by large variations in seismic wave velocities. Despite the complexity of the region little is known about the detailed lithospheric structure. Using data from 29 new broadband seismic stations in the region, a unified velocity structure is developed using teleseismic receiver functions and surface waves. Love and Rayleigh surface waves dispersion curves have been derived from event-based analysis and ambient-noise correlation. We jointly inverted the receiver functions with the surface wave dispersion curves to determine absolute shear wave velocity and important discontinuities such as sedimentary layer, Moho, lithospheric-asthenospheric boundary. Wemore » combined these new station results with Eastern Turkey Seismic Experiment results (29 stations). Caspian Sea and Kura basin underlained by one of the thickest sediments in the world. Therefore, short-period surface waves are observed to be very slow. The strong crustal multiples in receiver functions and the slow velocities in upper crust indicate the presence of thick sedimentary unit (up to 20 km). Crustal thickness varies from 34 to 52 km in the region. The thickest crust is in Lesser Caucasus and the thinnest is in the Arabian Plate. The lithospheric mantle in the Greater Caucasus and the Kura depression is faster than the Anatolian Plateau and Lesser Caucasus. This possibly indicates the presence of cold lithosphere. The lower crust is slowest in the northeastern part of the Anatolian Plateau where Holocene volcanoes are located.« less

Quantitative phase and texture angularity analysis of brain white matter lesions in multiple sclerosis

NASA Astrophysics Data System (ADS)

Baxandall, Shalese; Sharma, Shrushrita; Zhai, Peng; Pridham, Glen; Zhang, Yunyan

2018-03-01

Structural changes to nerve fiber tracts are extremely common in neurological diseases such as multiple sclerosis (MS). Accurate quantification is vital. However, while nerve fiber damage is often seen as multi-focal lesions in magnetic resonance imaging (MRI), measurement through visual perception is limited. Our goal was to characterize the texture pattern of the lesions in MRI and determine how texture orientation metrics relate to lesion structure using two new methods: phase congruency and multi-resolution spatial-frequency analysis. The former aims to optimize the detection of the `edges and corners' of a structure, and the latter evaluates both the radial and angular distributions of image texture associated with the various forming scales of a structure. The radial texture spectra were previously confirmed to measure the severity of nerve fiber damage, and were thus included for validation. All measures were also done in the control brain white matter for comparison. Using clinical images of MS patients, we found that both phase congruency and weighted mean phase detected invisible lesion patterns and were significantly greater in lesions, suggesting higher structure complexity, than the control tissue. Similarly, multi-angular spatial-frequency analysis detected much higher texture across the whole frequency spectrum in lesions than the control areas. Such angular complexity was consistent with findings from radial texture. Analysis of the phase and texture alignment may prove to be a useful new approach for assessing invisible changes in lesions using clinical MRI and thereby lead to improved management of patients with MS and similar disorders.

Deficits of long-term memory in ecstasy users are related to cognitive complexity of the task.

PubMed

Brown, John; McKone, Elinor; Ward, Jeff

2010-03-01

Despite animal evidence that methylenedioxymethamphetamine (ecstasy) causes lasting damage in brain regions related to long-term memory, results regarding human memory performance have been variable. This variability may reflect the cognitive complexity of the memory tasks. However, previous studies have tested only a limited range of cognitive complexity. Furthermore, comparisons across different studies are made difficult by regional variations in ecstasy composition and patterns of use. The objective of this study is to evaluate ecstasy-related deficits in human verbal memory over a wide range of cognitive complexity using subjects drawn from a single geographical population. Ecstasy users were compared to non-drug using controls on verbal tasks with low cognitive complexity (stem completion), moderate cognitive complexity (stem-cued recall and word list learning) and high cognitive complexity (California Verbal Learning Test, Verbal Paired Associates and a novel Verbal Triplet Associates test). Where significant differences were found, both groups were also compared to cannabis users. More cognitively complex memory tasks were associated with clearer ecstasy-related deficits than low complexity tasks. In the most cognitively demanding task, ecstasy-related deficits remained even after multiple learning opportunities, whereas the performance of cannabis users approached that of non-drug using controls. Ecstasy users also had weaker deliberate strategy use than both non-drug and cannabis controls. Results were consistent with the proposal that ecstasy-related memory deficits are more reliable on tasks with greater cognitive complexity. This could arise either because such tasks require a greater contribution from the frontal lobe or because they require greater interaction between multiple brain regions.

Divergent population structure and climate associations of a chromosomal inversion polymorphism across the Mimulus guttatus species complex

PubMed Central

Oneal, Elen; Lowry, David B.; Wright, Kevin M.; Zhu, Zhirui; Willis, John H.

2014-01-01

Chromosomal rearrangement polymorphisms are common and increasingly found to be associated with adaptive ecological divergence and speciation. Rearrangements, such as inversions, reduce recombination in heterozygous individuals and thus can protect favourable allelic combinations at linked loci, facilitating their spread in the presence of gene flow. Recently, we identified a chromosomal inversion polymorphism that contributes to ecological adaptation and reproductive isolation between annual and perennial ecotypes of the yellow monkeyflower, Mimulus guttatus. Here we evaluate the population genetic structure of this inverted region in comparison with the collinear regions of the genome across the M. guttatus species complex. We tested whether annual and perennial M. guttatus exhibit different patterns of divergence for loci in the inverted and noninverted regions of the genome. We then evaluated whether there are contrasting climate associations with these genomic regions through redundancy analysis. We found that the inversion exhibits broadly different patterns of divergence among annual and perennial M. guttatus and is associated with environmental variation across population accessions. This study is the first widespread population genetic survey of the diversity of the M. guttatus species complex. Our findings contribute to a greater understanding of morphological, ecological, and genetic evolutionary divergence across this highly diverse group of closely related ecotypes and species. Finally, understanding species relationships among M. guttatus sp. has hitherto been stymied by accumulated evidence of substantial gene flow among populations as well as designated species. Nevertheless, our results shed light on these relationships and provide insight into adaptation in life history traits within the complex. PMID:24796267

Growth Mode Transition in Complex Oxide Heteroepitaxy: Atomically Resolved Studies

DOE PAGES

Tselev, Alexander; Vasudevan, Rama K.; Gianfrancesco, Anthony G.; ...

2016-04-04

Here we performed investigations of the atomic-scale surface structure of epitaxial La 5/8Ca 3/8MnO 3 thin films as a model system dependent on growth conditions in pulsed laser deposition with emphasis on film growth kinetics. Postdeposition in situ scanning tunneling microscopy was combined with in operando reflective high-energy electron diffraction to monitor the film growth and ex situ X-ray diffraction for structural analysis. We find a correlation between the out-of-plane lattice parameter and both adspecies mobility and height of the Ehrlich–Schwoebel barrier, with mobility of adatoms greater over the cationically stoichiometric terminations. We find that the data suggest that themore » out-of-plane lattice parameter is dependent on the mechanism of epitaxial strain relaxation, which is controlled by the oxidative power of the deposition environment.« less

Who was the agent? The neural correlates of reanalysis processes during sentence comprehension.

PubMed

Hirotani, Masako; Makuuchi, Michiru; Rüschemeyer, Shirley-Ann; Friederici, Angela D

2011-11-01

Sentence comprehension is a complex process. Besides identifying the meaning of each word and processing the syntactic structure of a sentence, it requires the computation of thematic information, that is, information about who did what to whom. The present fMRI study investigated the neural basis for thematic reanalysis (reanalysis of the thematic roles initially assigned to noun phrases in a sentence) and its interplay with syntactic reanalysis (reanalysis of the underlying syntactic structure originally constructed for a sentence). Thematic reanalysis recruited a network consisting of Broca's area, that is, the left pars triangularis (LPT), and the left posterior superior temporal gyrus, whereas only LPT showed greater sensitivity to syntactic reanalysis. These data provide direct evidence for a functional neuroanatomical basis for two linguistically motivated reanalysis processes during sentence comprehension. Copyright © 2010 Wiley-Liss, Inc.

Cellular automaton simulation examining progenitor hierarchy structure effects on mammary ductal carcinoma in situ.

PubMed

Bankhead, Armand; Magnuson, Nancy S; Heckendorn, Robert B

2007-06-07

A computer simulation is used to model ductal carcinoma in situ, a form of non-invasive breast cancer. The simulation uses known histological morphology, cell types, and stochastic cell proliferation to evolve tumorous growth within a duct. The ductal simulation is based on a hybrid cellular automaton design using genetic rules to determine each cell's behavior. The genetic rules are a mutable abstraction that demonstrate genetic heterogeneity in a population. Our goal was to examine the role (if any) that recently discovered mammary stem cell hierarchies play in genetic heterogeneity, DCIS initiation and aggressiveness. Results show that simpler progenitor hierarchies result in greater genetic heterogeneity and evolve DCIS significantly faster. However, the more complex progenitor hierarchy structure was able to sustain the rapid reproduction of a cancer cell population for longer periods of time.

The Later Paleozoic granites of the Greater Caucasus Fore Range zone: geochemistry, magnetic properties and the structural and metamorphic evolution.

NASA Astrophysics Data System (ADS)

Kamzolkin, Vladimir; Latyshev, Anton; Ivanov, Stanislav; Vidjapin, Jury

2017-04-01

Clarification of the position of the granitic intrusions associated with the Blyb Metamorphic Complex is the important problem of the reconstruction of the structural evolution of the Greater Caucasus Fore Range zone. Based of the rock geochemistry we found out that the quartz diorites, granodiorites and syeno-granites of the BMC formed in suprasubduction conditions and refer to I-type granites. However, their emplacement was multistage coinciding with the various stages of the BMC evolution. We detected the mineral associations typical for the epidote-amphibolite facies in the Balkan massif, but these metamorphic features are absent in the granodiorite intrusions in the southern part of the Fore Range zone. Thus, quartz diorites of the Balkan intrusion intruded after the high-pressure metamorphism of the host rocks, but before the epidote-amphibolite stage, and the Southern granodiorite intrusions are younger. The measurements of the anisotropy of the magnetic susceptibility (AMS) in the Balkan intrusion indicated the shallow orientation of the minimal (north-eastern strike) and maximal (north-western strike) axes of the AMS ellipsoid. This result is compatible with the idea of the north-east compression fixed in the fold deformation structures of the BMC host rocks (Vidyapin, Kamzolkin, 2015). However, the macroscopic foliation in the granites dips to the east steeply. The discrepancy of the texture orientation of the granites, the host rock structure and the magnetic fabric can be explained as a result of the repeated changes of the stress field during the evolution of the Fore Range nappe structures. The reported study was partially supported by RFBR, research projects No. 16-35-00571mol_a; 16-05-01012a.

High-resolution crystal structures of Drosophila melanogaster angiotensin-converting enzyme in complex with novel inhibitors and antihypertensive drugs.

PubMed

Akif, Mohd; Georgiadis, Dimitris; Mahajan, Aman; Dive, Vincent; Sturrock, Edward D; Isaac, R Elwyn; Acharya, K Ravi

2010-07-16

Angiotensin I-converting enzyme (ACE), one of the central components of the renin-angiotensin system, is a key therapeutic target for the treatment of hypertension and cardiovascular disorders. Human somatic ACE (sACE) has two homologous domains (N and C). The N- and C-domain catalytic sites have different activities toward various substrates. Moreover, some of the undesirable side effects of the currently available and widely used ACE inhibitors may arise from their targeting both domains leading to defects in other pathways. In addition, structural studies have shown that although both these domains have much in common at the inhibitor binding site, there are significant differences and these are greater at the peptide binding sites than regions distal to the active site. As a model system, we have used an ACE homologue from Drosophila melanogaster (AnCE, a single domain protein with ACE activity) to study ACE inhibitor binding. In an extensive study, we present high-resolution structures for native AnCE and in complex with six known antihypertensive drugs, a novel C-domain sACE specific inhibitor, lisW-S, and two sACE domain-specific phosphinic peptidyl inhibitors, RXPA380 and RXP407 (i.e., nine structures). These structures show detailed binding features of the inhibitors and highlight subtle changes in the orientation of side chains at different binding pockets in the active site in comparison with the active site of N- and C-domains of sACE. This study provides information about the structure-activity relationships that could be utilized for designing new inhibitors with improved domain selectivity for sACE. 2010 Elsevier Ltd. All rights reserved.

The structural inventory of a small complex impact crater: Jebel Waqf as Suwwan, Jordan

NASA Astrophysics Data System (ADS)

Kenkmann, Thomas; Sturm, Sebastian; Krüger, Tim; Salameh, Elias; Al-Raggad, Marwan; Konsul, Khalil

2017-07-01

The investigation of terrestrial impact structures is crucial to gain an in-depth understanding of impact cratering processes in the solar system. Here, we use the impact structure Jebel Waqf as Suwwan, Jordan, as a representative for crater formation into a layered sedimentary target with contrasting rheology. The complex crater is moderately eroded (300-420 m) with an apparent diameter of 6.1 km and an original rim fault diameter of 7 km. Based on extensive field work, IKONOS imagery, and geophysical surveying we present a novel geological map of the entire crater structure that provides the basis for structural analysis. Parametric scaling indicates that the structural uplift (250-350 m) and the depth of the ring syncline (<200 m) are anomalously low. The very shallow relief of the crater along with a NE vergence of the asymmetric central uplift and the enhanced deformations in the up-range and down-range sectors of the annular moat and crater rim suggest that the impact was most likely a very oblique one ( 20°). One of the major consequences of the presence of the rheologically anisotropic target was that extensive strata buckling occurred during impact cratering both on the decameter as well as on the hundred-meter scale. The crater rim is defined by a circumferential normal fault dipping mostly toward the crater. Footwall strata beneath the rim fault are bent-up in the down-range sector but appear unaffected in the up-range sector. The hanging wall displays various synthetic and antithetic rotations in the down-range sector but always shows antithetic block rotation in the up-range sector. At greater depth reverse faulting or folding is indicated at the rim indicating that the rim fault was already formed during the excavation stage.

DL_MG: A Parallel Multigrid Poisson and Poisson-Boltzmann Solver for Electronic Structure Calculations in Vacuum and Solution.

PubMed

Womack, James C; Anton, Lucian; Dziedzic, Jacek; Hasnip, Phil J; Probert, Matt I J; Skylaris, Chris-Kriton

2018-03-13

The solution of the Poisson equation is a crucial step in electronic structure calculations, yielding the electrostatic potential-a key component of the quantum mechanical Hamiltonian. In recent decades, theoretical advances and increases in computer performance have made it possible to simulate the electronic structure of extended systems in complex environments. This requires the solution of more complicated variants of the Poisson equation, featuring nonhomogeneous dielectric permittivities, ionic concentrations with nonlinear dependencies, and diverse boundary conditions. The analytic solutions generally used to solve the Poisson equation in vacuum (or with homogeneous permittivity) are not applicable in these circumstances, and numerical methods must be used. In this work, we present DL_MG, a flexible, scalable, and accurate solver library, developed specifically to tackle the challenges of solving the Poisson equation in modern large-scale electronic structure calculations on parallel computers. Our solver is based on the multigrid approach and uses an iterative high-order defect correction method to improve the accuracy of solutions. Using two chemically relevant model systems, we tested the accuracy and computational performance of DL_MG when solving the generalized Poisson and Poisson-Boltzmann equations, demonstrating excellent agreement with analytic solutions and efficient scaling to ∼10 9 unknowns and 100s of CPU cores. We also applied DL_MG in actual large-scale electronic structure calculations, using the ONETEP linear-scaling electronic structure package to study a 2615 atom protein-ligand complex with routinely available computational resources. In these calculations, the overall execution time with DL_MG was not significantly greater than the time required for calculations using a conventional FFT-based solver.

Metrology of deep trench etched memory structures using 3D scatterometry

NASA Astrophysics Data System (ADS)

Reinig, Peter; Dost, Rene; Moert, Manfred; Hingst, Thomas; Mantz, Ulrich; Moffitt, Jasen; Shakya, Sushil; Raymond, Christopher J.; Littau, Mike

2005-05-01

Scatterometry is receiving considerable attention as an emerging optical metrology in the silicon industry. One area of progress in deploying these powerful measurements in process control is performing measurements on real device structures, as opposed to limiting scatterometry measurements to periodic structures, such as line-space gratings, placed in the wafer scribe. In this work we will discuss applications of 3D scatterometry to the measurement of advanced trench memory devices. This is a challenging and complex scatterometry application that requires exceptionally high-performance computational abilities. In order to represent the physical device, the relatively tall structures require a high number of slices in the rigorous coupled wave analysis (RCWA) theoretical model. This is complicated further by the presence of an amorphous silicon hard mask on the surface, which is highly sensitive to reflectance scattering and therefore needs to be modeled in detail. The overall structure is comprised of several layers, with the trenches presenting a complex bow-shape sidewall that must be measured. Finally, the double periodicity in the structures demands significantly greater computational capabilities. Our results demonstrate that angular scatterometry is sensitive to the key parameters of interest. The influence of further model parameters and parameter cross correlations have to be carefully taken into account. Profile results obtained by non-library optimization methods compare favorably with cross-section SEM images. Generating a model library suitable for process control, which is preferred for precision, presents numerical throughput challenges. Details will be discussed regarding library generation approaches and strategies for reducing the numerical overhead. Scatterometry and SEM results will be compared, leading to conclusions about the feasibility of this advanced application.

Structure-reactivity relationship of naphthenic acids in the photocatalytic degradation process.

PubMed

de Oliveira Livera, Diogo; Leshuk, Tim; Peru, Kerry M; Headley, John V; Gu, Frank

2018-06-01

Bitumen extraction in Canada's oil sands generates oil sands process-affected water (OSPW) as a toxic by-product. Naphthenic acids (NAs) contribute to the water's toxicity, and treatment methods may need to be implemented to enable safe discharge. Heterogeneous photocatalysis is a promising advanced oxidation process (AOP) for OSPW remediation, however, its successful implementation requires understanding of the complicated relationship between structure and reactivity of NAs. This work aimed to study the effect of various structural properties of model compounds on the photocatalytic degradation kinetics via high resolution mass spectrometry (HRMS), including diamondoid structures, heteroatomic species, and degree of unsaturation. The rate of photocatalytic treatment increased significantly with greater structural complexity, namely with carbon number, aromaticity and degree of cyclicity, properties that render particular NAs recalcitrant to biodegradation. It is hypothesized that a superoxide radical-mediated pathway explains these observations and offers additional benefits over traditional hydroxyl radical-based AOPs. Detailed structure-reactivity investigations of NAs in photocatalysis have not previously been undertaken, and the results described herein illustrate the potential benefit of combining photocatalysis and biodegradation as a complete OSPW remediation technology. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evidence that the respiratory syncytial virus polymerase complex associates with lipid rafts in virus-infected cells: a proteomic analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDonald, Terence P.; Pitt, Andrew R.; Brown, Gaie

2004-12-05

The interaction between the respiratory syncytial virus (RSV) polymerase complex and lipid rafts was examined in HEp2 cells. Lipid-raft membranes were prepared from virus-infected cells and their protein content was analysed by Western blotting and mass spectrometry. This analysis revealed the presence of the N, P, L, M2-1 and M proteins. However, these proteins appeared to differ from one another in their association with these structures, with the M2-1 protein showing a greater partitioning into raft membranes compared to that of the N, P or M proteins. Determination of the polymerase activity profile of the gradient fractions revealed that 95%more » of the detectable viral enzyme activity was associated with lipid-raft membranes. Furthermore, analysis of virus-infected cells by confocal microscopy suggested an association between these proteins and the raft-lipid, GM1. Together, these results provide evidence that the RSV polymerase complex is able to associate with lipid rafts in virus-infected cells.« less

A photofunctional bottom-up bis(dipyrrinato)zinc(II) complex nanosheet

PubMed Central

Sakamoto, Ryota; Hoshiko, Ken; Liu, Qian; Yagi, Toshiki; Nagayama, Tatsuhiro; Kusaka, Shinpei; Tsuchiya, Mizuho; Kitagawa, Yasutaka; Wong, Wai-Yeung; Nishihara, Hiroshi

2015-01-01

Two-dimensional polymeric nanosheets have recently gained much attention, particularly top-down nanosheets such as graphene and metal chalcogenides originating from bulk-layered mother materials. Although molecule-based bottom-up nanosheets manufactured directly from molecular components can exhibit greater structural diversity than top-down nanosheets, the bottom-up nanosheets reported thus far lack useful functionalities. Here we show the design and synthesis of a bottom-up nanosheet featuring a photoactive bis(dipyrrinato)zinc(II) complex motif. A liquid/liquid interfacial synthesis between a three-way dipyrrin ligand and zinc(II) ions results in a multi-layer nanosheet, whereas an air/liquid interfacial reaction produces a single-layer or few-layer nanosheet with domain sizes of >10 μm on one side. The bis(dipyrrinato)zinc(II) metal complex nanosheet is easy to deposit on various substrates using the Langmuir–Schäfer process. The nanosheet deposited on a transparent SnO2 electrode functions as a photoanode in a photoelectric conversion system, and is thus the first photofunctional bottom-up nanosheet. PMID:25831973

Synthesis and structural characterization of dioxomolybdenum and dioxotungsten hydroxamato complexes and their function in the protection of radiation induced DNA damage.

PubMed

Paul, Shiv Shankar; Selim, Md; Saha, Abhijit; Mukherjea, Kalyan K

2014-02-21

The synthesis and structural characterization of two novel dioxomolybdenum(VI) (1) and dioxotungsten(VI) (2) complexes with 2-phenylacetylhydroxamic acid (PAHH) [M(O)2(PAH)2] [M = Mo, W] have been accomplished. The dioxomolybdenum(VI) and dioxotungsten(VI) moiety is coordinated by the hydroxamate group (-CONHO(-)) of the 2-phenylacetylhydroxamate (PAH) ligand in a bi-dentate fashion. In both the complexes the PAHH ligand is coordinated through oxygen atoms forming a five membered chelate. The hydrogen atom of N-H of the hydroxamate group is engaged in intermolecular H-bonding with the carbonyl oxygen of another coordinated hydroxamate ligand, thereby forming an extended 1D chain. The ligand as well as both the complexes exhibit the ability to protect from radiation induced damage both in CTDNA as well as in pUC19 plasmid DNA. As the damage to DNA is caused by the radicals generated during radiolysis, its scavenging imparts protection from the damage to DNA. To understand the mechanism of protection, binding affinities of the ligand and the complex with DNA were determined using absorption and emission spectral studies and viscosity measurements, whereby the results indicate that both the complexes and the hydroxamate ligand interact with calf thymus DNA in the minor groove. The intrinsic binding constants, obtained from UV-vis studies, are 7.2 × 10(3) M(-1), 5.2 × 10(4) M(-1) and 1.2 × 10(4) M(-1) for the ligand and complexes 1 and 2 respectively. The Stern-Volmer quenching constants obtained from a luminescence study for both the complexes are 5.6 × 10(4) M(-1) and 1.6 × 10(4) M(-1) respectively. The dioxomolybdenum(VI) complex is found to be a more potent radioprotector compared to the dioxotungsten(VI) complex and the ligand. Radical scavenging chemical studies suggest that the complexes have a greater ability to scavenge both the hydroxyl as well as the superoxide radicals compared to the ligand. The free radical scavenging ability of the ligand and the complexes was further established by EPR spectroscopy using a stable free radical, the DPPH, as a probe. The experimental results of DNA binding are further supported by molecular docking studies.

Inter-subject synchronization of brain responses during natural music listening

PubMed Central

Abrams, Daniel A.; Ryali, Srikanth; Chen, Tianwen; Chordia, Parag; Khouzam, Amirah; Levitin, Daniel J.; Menon, Vinod

2015-01-01

Music is a cultural universal and a rich part of the human experience. However, little is known about common brain systems that support the processing and integration of extended, naturalistic ‘real-world’ music stimuli. We examined this question by presenting extended excerpts of symphonic music, and two pseudomusical stimuli in which the temporal and spectral structure of the Natural Music condition were disrupted, to non-musician participants undergoing functional brain imaging and analysing synchronized spatiotemporal activity patterns between listeners. We found that music synchronizes brain responses across listeners in bilateral auditory midbrain and thalamus, primary auditory and auditory association cortex, right-lateralized structures in frontal and parietal cortex, and motor planning regions of the brain. These effects were greater for natural music compared to the pseudo-musical control conditions. Remarkably, inter-subject synchronization in the inferior colliculus and medial geniculate nucleus was also greater for the natural music condition, indicating that synchronization at these early stages of auditory processing is not simply driven by spectro-temporal features of the stimulus. Increased synchronization during music listening was also evident in a right-hemisphere fronto-parietal attention network and bilateral cortical regions involved in motor planning. While these brain structures have previously been implicated in various aspects of musical processing, our results are the first to show that these regions track structural elements of a musical stimulus over extended time periods lasting minutes. Our results show that a hierarchical distributed network is synchronized between individuals during the processing of extended musical sequences, and provide new insight into the temporal integration of complex and biologically salient auditory sequences. PMID:23578016

Ab initio study of charge transfer between lithium and aromatic hydrocarbons. Can the results be directly transferred to the lithium-graphene interaction?

PubMed

Sadlej-Sosnowska, N

2014-08-28

We have used electronic density calculations to study neutral complexes of Li with aromatic hydrocarbons. The charge transferred between a Li atom and benzene, coronene, circumcoronene, and circumcircumcoronene has been studied by ab initio methods (at the HF and MP2 level). Toward this aim, the method of integrating electron density in two cuboid fragments of space was applied. One of the fragments was constructed so that it enclosed the bulk of the electron density of lithium; the second, the bulk of the electron density of hydrocarbon. It was found that for each complex two conformations were identified: the most stable with a greater vertical Li-hydrocarbon distance, on the order of 2.5 Å, and another of higher energy with a corresponding distance less than 2 Å. In all cases the transfer of a fractional number, 0.1-0.3 electrons, between Li and hydrocarbon was found; however, the direction of the transfer was not the same in all complexes investigated. The structures of complexes of the first configuration could be represented as Li(σ-)···AH(σ+), whereas the opposite direction of charge transfer was found for complexes of the second configuration, with higher energy. The directions of the dipole moments in the complexes supported these conclusions because they directly measure the redistribution of electron density in a complex with respect to substrates.

Impact of Diet-Induced Obesity and Testosterone Deficiency on the Cardiovascular System: A Novel Rodent Model Representative of Males with Testosterone-Deficient Metabolic Syndrome (TDMetS)

PubMed Central

Donner, Daniel G.; Elliott, Grace E.; Beck, Belinda R.; Bulmer, Andrew C.; Du Toit, Eugene F.

2015-01-01

Introduction Current models of obesity utilise normogonadic animals and neglect the strong relationships between obesity-associated metabolic syndrome (MetS) and male testosterone deficiency (TD). The joint presentation of these conditions has complex implications for the cardiovascular system that are not well understood. We have characterised and investigated three models in male rats: one of diet-induced obesity with the MetS; a second using orchiectomised rats mimicking TD; and a third combining MetS with TD which we propose is representative of males with testosterone deficiency and the metabolic syndrome (TDMetS). Methods Male Wistar rats (n = 24) were randomly assigned to two groups and provided ad libitum access to normal rat chow (CTRL) or a high fat/high sugar/low protein “obesogenic” diet (OGD) for 28 weeks (n = 12/group). These groups were further sub-divided into sham-operated or orchiectomised (ORX) animals to mimic hypogonadism, with and without diet-induced obesity (n = 6/group). Serum lipids, glucose, insulin and sex hormone concentrations were determined. Body composition, cardiovascular structure and function; and myocardial tolerance to ischemia-reperfusion were assessed. Results OGD-fed animals had 72% greater fat mass; 2.4-fold greater serum cholesterol; 2.3-fold greater serum triglycerides and 3-fold greater fasting glucose (indicative of diabetes mellitus) compared to CTRLs (all p<0.05). The ORX animals had reduced serum testosterone and left ventricle mass (p<0.05). In addition to the combined differences observed in each of the isolated models, the OGD, ORX and OGD+ORX models each had greater CK-MB levels following in vivo cardiac ischemia-reperfusion insult compared to CTRLs (p<0.05). Conclusion Our findings provide evidence to support that the MetS and TD independently impair myocardial tolerance to ischemia-reperfusion. The combined OGD+ORX phenotype described in this study is a novel animal model with associated cardiovascular risk factors and complex myocardial pathology which may be representative of male patients presenting with TDMetS. PMID:26366723

The importance of topographic corrections on magnetotelluric response data from rugged regions of Anatolia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guerer, A.; Ilkisik, O.M.

1997-01-01

Topographic irregularities cause some distortions of magnetotelluric (MT) fields. In the vicinity of a topographic feature, the TM-mode distortion increases with the height and inclination of the slope. It is well-known that TM-mode topographic effects are much greater than TE-mode distortions. The authors have made a study of MT anomalies in TM-mode due to two-dimensional topography. In order to reduce these effects, the distortion tensor stripping technique was used. After corrections, the resulting data can be interpreted as if they were obtained over a flat surface and depend only on the subsurface structure. However, this technique sometimes causes some geometricalmore » distortions of the real subsurface structure. One of the aims is to overcome this failure. The authors have modified the correction coefficients by considering the actual one-dimensional geology. Model studies showed that this approach is especially useful in removing the terrain effects on complex 2D subsurface structures. The other purpose of this study is to emphasize the importance of a proper terrain correction for data from sites having mountainous topography over complex geology, e.g., strike-slip faults, suture zones and rift valleys. Some examples of MT data sets collected from the North Anatolian Fault Zone and from the thrust regions of the Western Taurides will be presented.« less

Distributions of vesicular glutamate transporters 1 and 2 in the visual system of tree shrews (Tupaia belangeri).

PubMed

Balaram, P; Isaamullah, M; Petry, H M; Bickford, M E; Kaas, J H

2015-08-15

Vesicular glutamate transporter (VGLUT) proteins regulate the storage and release of glutamate from synapses of excitatory neurons. Two isoforms, VGLUT1 and VGLUT2, are found in most glutamatergic projections across the mammalian visual system, and appear to differentially identify subsets of excitatory projections between visual structures. To expand current knowledge on the distribution of VGLUT isoforms in highly visual mammals, we examined the mRNA and protein expression patterns of VGLUT1 and VGLUT2 in the lateral geniculate nucleus (LGN), superior colliculus, pulvinar complex, and primary visual cortex (V1) in tree shrews (Tupaia belangeri), which are closely related to primates but classified as a separate order (Scandentia). We found that VGLUT1 was distributed in intrinsic and corticothalamic connections, whereas VGLUT2 was predominantly distributed in subcortical and thalamocortical connections. VGLUT1 and VGLUT2 were coexpressed in the LGN and in the pulvinar complex, as well as in restricted layers of V1, suggesting a greater heterogeneity in the range of efferent glutamatergic projections from these structures. These findings provide further evidence that VGLUT1 and VGLUT2 identify distinct populations of excitatory neurons in visual brain structures across mammals. Observed variations in individual projections may highlight the evolution of these connections through the mammalian lineage. © 2015 Wiley Periodicals, Inc.

Metasurface Broadband Solar Absorber.

PubMed

Azad, Abul K; Kort-Kamp, Wilton J M; Sykora, Milan; Weisse-Bernstein, Nina R; Luk, Ting S; Taylor, Antoinette J; Dalvit, Diego A R; Chen, Hou-Tong

2016-02-01

We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

Competition between conceptual relations affects compound recognition: the role of entropy.

PubMed

Schmidtke, Daniel; Kuperman, Victor; Gagné, Christina L; Spalding, Thomas L

2016-04-01

Previous research has suggested that the conceptual representation of a compound is based on a relational structure linking the compound's constituents. Existing accounts of the visual recognition of modifier-head or noun-noun compounds posit that the process involves the selection of a relational structure out of a set of competing relational structures associated with the same compound. In this article, we employ the information-theoretic metric of entropy to gauge relational competition and investigate its effect on the visual identification of established English compounds. The data from two lexical decision megastudies indicates that greater entropy (i.e., increased competition) in a set of conceptual relations associated with a compound is associated with longer lexical decision latencies. This finding indicates that there exists competition between potential meanings associated with the same complex word form. We provide empirical support for conceptual composition during compound word processing in a model that incorporates the effect of the integration of co-activated and competing relational information.

Efficient estimation of three-dimensional covariance and its application in the analysis of heterogeneous samples in cryo-electron microscopy

PubMed Central

Liao, Hstau Y.; Hashem, Yaser; Frank, Joachim

2015-01-01

Summary Single-particle cryogenic electron microscopy (cryo-EM) is a powerful tool for the study of macromolecular structures at high resolution. Classification allows multiple structural states to be extracted and reconstructed from the same sample. One classification approach is via the covariance matrix, which captures the correlation between every pair of voxels. Earlier approaches employ computing-intensive resampling and estimate only the eigenvectors of the matrix, which are then used in a separate fast classification step. We propose an iterative scheme to explicitly estimate the covariance matrix in its entirety. In our approach, the flexibility in choosing the solution domain allows us to examine a part of the molecule in greater detail. 3D covariance maps obtained in this way from experimental data (cryo-EM images of the eukaryotic pre-initiation complex) prove to be in excellent agreement with conclusions derived by using traditional approaches, revealing in addition the interdependencies of ligand bindings and structural changes. PMID:25982529

Efficient estimation of three-dimensional covariance and its application in the analysis of heterogeneous samples in cryo-electron microscopy.

PubMed

Liao, Hstau Y; Hashem, Yaser; Frank, Joachim

2015-06-02

Single-particle cryogenic electron microscopy (cryo-EM) is a powerful tool for the study of macromolecular structures at high resolution. Classification allows multiple structural states to be extracted and reconstructed from the same sample. One classification approach is via the covariance matrix, which captures the correlation between every pair of voxels. Earlier approaches employ computing-intensive resampling and estimate only the eigenvectors of the matrix, which are then used in a separate fast classification step. We propose an iterative scheme to explicitly estimate the covariance matrix in its entirety. In our approach, the flexibility in choosing the solution domain allows us to examine a part of the molecule in greater detail. Three-dimensional covariance maps obtained in this way from experimental data (cryo-EM images of the eukaryotic pre-initiation complex) prove to be in excellent agreement with conclusions derived by using traditional approaches, revealing in addition the interdependencies of ligand bindings and structural changes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Neoproteoglycans in tissue engineering.

PubMed

Weyers, Amanda; Linhardt, Robert J

2013-05-01

Proteoglycans, comprised of a core protein to which glycosaminoglycan chains are covalently linked, are an important structural and functional family of macromolecules found in the extracellular matrix. Advances in our understanding of biological interactions have lead to a greater appreciation for the need to design tissue engineering scaffolds that incorporate mimetics of key extracellular matrix components. A variety of synthetic and semisynthetic molecules and polymers have been examined by tissue engineers that serve as structural, chemical and biological replacements for proteoglycans. These proteoglycan mimetics have been referred to as neoproteoglycans and serve as functional and therapeutic replacements for natural proteoglycans that are often unavailable for tissue engineering studies. Although neoproteoglycans have important limitations, such as limited signaling ability and biocompatibility, they have shown promise in replacing the natural activity of proteoglycans through cell and protein binding interactions. This review focuses on the recent in vivo and in vitro tissue engineering applications of three basic types of neoproteoglycan structures, protein-glycosaminoglycan conjugates, nano-glycosaminoglycan composites and polymer-glycosaminoglycan complexes. © 2013 The Authors Journal compilation © 2013 FEBS.

Neoproteoglycans in tissue engineering

PubMed Central

Weyers, Amanda; Linhardt, Robert J.

2014-01-01

Proteoglycans, comprised of a core protein to which glycosaminoglycan chains are covalently linked, are an important structural and functional family of macromolecules found in the extracellular matrix. Advances in our understanding of biological interactions have lead to a greater appreciation for the need to design tissue engineering scaffolds that incorporate mimetics of key extracellular matrix components. A variety of synthetic and semisynthetic molecules and polymers have been examined by tissue engineers that serve as structural, chemical and biological replacements for proteoglycans. These proteoglycan mimetics have been referred to as neoproteoglycans and serve as functional and therapeutic replacements for natural proteoglycans that are often unavailable for tissue engineering studies. Although neoproteoglycans have important limitations, such as limited signaling ability and biocompatibility, they have shown promise in replacing the natural activity of proteoglycans through cell and protein binding interactions. This review focuses on the recent in vivo and in vitro tissue engineering applications of three basic types of neoproteoglycan structures, protein–glycosaminoglycan conjugates, nano-glycosaminoglycan composites and polymer–glycosaminoglycan complexes. PMID:23399318

Optical Trapping and Manipulation in the Single- and Many-Body Limits

NASA Astrophysics Data System (ADS)

Spalding, Gabriel

2007-03-01

Analysis of optical dipole/scattering forces can be done at a variety of levels, some of which are appropriate to the undergraduate curriculum. The addition of simple holographic techniques has extended the basic capabilities of optical tweezing, making it a more viable tool for the assembly of micro-systems and organization of specimens into user-defined structures. In 2D, we have demonstrated an approach that allows optical forces alone to assemble microparticles over macroscopic areas. 3D structures pose greater challenges, but also significant opportunities. Our early efforts at filling a 3D lattice of optical traps led to an appreciation for the dynamics of injected microparticle streams, which yield a surprisingly successful method of sorting or re- routing within microfludic environments. We will discuss the status of efforts using optical trapping to create static many-body structures (both simple and complex), as well as recent results on dynamic interactions. At the same time, some of these techniques have clear pedagogical value, as will be emphasized.

Insights into the multi-scale structure and digestibility of heat-moisture treated rice starch.

PubMed

Wang, Hongwei; Liu, Yufan; Chen, Ling; Li, Xiaoxi; Wang, Jun; Xie, Fengwei

2018-03-01

The digestibility and structural changes of rice starch induced by heat-moisture treatment (HMT) were investigated, and the relationships among the moisture content-starch structure-starch digestibility were revealed. HMT could simultaneously disorder and reassemble the rice starch molecules across multi-scale lengths and convert some fractions of rapidly-digestible starch (RDS) into slowly-digestible starch (SDS) and resistant starch (RS). In particular, the HMT rice starch with less than 30% moisture content showed a higher SDS+RS content (25.0%). During HMT, SDS and RS were preferably formed by the degraded starch molecules with M w between 4×10 5 and 4×10 6 g/mol, single helices and amylose-lipids complexes that were formed by degraded starch chains with higher thermal stability and crystalline lamellae with greater thicknesses. Thus, our research suggests a potential approach using HMT to control the digestion of starch products with desired digestibility. Copyright © 2017. Published by Elsevier Ltd.

Geology, Murzuk oil development could boost S. W. Libya prospects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, D.

1995-03-06

With the recent involvement of Repsol, Total, and OMV in developing the 2 billion bbl oil-in-place Murzuk field complex, an infrastructure will be finally constructed in western Libya which will act as a precursor to more exploration activity and development projects in the Murzuk and Ghadames basins. Murzuk, an intra-cratonic sag basin, is a huge ladle-shaped structural basin covering more than 400,000 sq km and extending beyond the borders of southern Libya. The structure of the area is quite simple. The sub-horizontal or gently dipping strata are faulted and the faults are most frequently parallel to the anticlinal axis. Tectonicmore » movements affected the basin to a greater or lesser degree from early Paleozoic (Caledonian) to post-Eocene (Alpine) times. The paper describes the exploration history; stratigraphy; the Ordovician, Silurian and Devonian, and Carboniferous reservoirs; source rocks; oil gravity and gas content; hydrogeologic constraints; aquifer influence on hydrocarbon accumulation; geologic structures; Murzuk field development; and acreage availability.« less

Three-dimensional simulations of void collapse in energetic materials

NASA Astrophysics Data System (ADS)

Rai, Nirmal Kumar; Udaykumar, H. S.

2018-03-01

The collapse of voids in porous energetic materials leads to hot-spot formation and reaction initiation. This work advances the current knowledge of the dynamics of void collapse and hot-spot formation using 3D reactive void collapse simulations in HMX. Four different void shapes, i.e., sphere, cylinder, plate, and ellipsoid, are studied. For all four shapes, collapse generates complex three-dimensional (3D) baroclinic vortical structures. The hot spots are collocated with regions of intense vorticity. The differences in the vortical structures for the different void shapes are shown to significantly impact the relative sensitivity of the voids. Voids of high surface area generate hot spots of greater intensity; intricate, highly contorted vortical structures lead to hot spots of corresponding tortuosity and therefore enhanced growth rates of reaction fronts. In addition, all 3D voids are shown to be more sensitive than their two-dimensional (2D) counterparts. The results provide physical insights into hot-spot formation and growth and point to the limitations of 2D analyses of hot-spot formation.

Canopy rainfall partitioning across an urbanization gradient in forest structure as characterized by terrestrial LiDAR

NASA Astrophysics Data System (ADS)

Mesta, D. C.; Van Stan, J. T., II; Yankine, S. A.; Cote, J. F.; Jarvis, M. T.; Hildebrandt, A.; Friesen, J.; Maldonado, G.

2017-12-01

As urbanization expands, greater forest area is shifting from natural stand structures to urban stand structures, like forest fragments and landscaped tree rows. Changes in forest canopy structure have been found to drastically alter the amount of rainwater reaching the surface. However, stormwater management models generally treat all forest structures (beyond needle versus broadleaved) similarly. This study examines the rainfall partitioning of Pinus spp. canopies along a natural-to-urban forest gradient and compares these to canopy structural measurements using terrestrial LiDAR. Throughfall and meteorological observations were also used to estimate parameters of the commonly-used Gash interception model. Preliminary findings indicate that as forest structure changed from natural, closed canopy conditions to semi-closed canopy fragments and, ultimately, to exposed urban landscaping tree rows, the interchange between throughfall and rainfall interception also changed. This shift in partitioning between throughfall and rainfall interception may be linked to intuitive parameters, like canopy closure and density, as well as more complex metrics, like the fine-scale patterning of gaps (ie, lacunarity). Thus, results indicate that not all forests of the same species should be treated the same by stormwater models. Rather, their canopy structural characteristics should be used to vary their hydrometeorological interactions.

Implementing the patient-centered medical home in complex adaptive systems: Becoming a relationship-centered patient-centered medical home.

PubMed

Flieger, Signe Peterson

This study explores the implementation experience of nine primary care practices becoming patient-centered medical homes (PCMH) as part of the New Hampshire Citizens Health Initiative Multi-Stakeholder Medical Home Pilot. The purpose of this study is to apply complex adaptive systems theory and relationship-centered organizations theory to explore how nine diverse primary care practices in New Hampshire implemented the PCMH model and to offer insights for how primary care practices can move from a structural PCMH to a relationship-centered PCMH. Eighty-three interviews were conducted with administrative and clinical staff at the nine pilot practices, payers, and conveners of the pilot between November and December 2011. The interviews were transcribed, coded, and analyzed using both a priori and emergent themes. Although there is value in the structural components of the PCMH (e.g., disease registries), these structures are not enough. Becoming a relationship-centered PCMH requires attention to reflection, sensemaking, learning, and collaboration. This can be facilitated by settings aside time for communication and relationship building through structured meetings about PCMH components as well as the implementation process itself. Moreover, team-based care offers a robust opportunity to move beyond the structures to focus on relationships and collaboration. (a) Recognize that PCMH implementation is not a linear process. (b) Implementing the PCMH from a structural perspective is not enough. Although the National Committee for Quality Assurance or other guidelines can offer guidance on the structural components of PCMH implementation, this should serve only as a starting point. (c) During implementation, set aside structured time for reflection and sensemaking. (d) Use team-based care as a cornerstone of transformation. Reflect on team structures and also interactions of the team members. Taking the time to reflect will facilitate greater sensemaking and learning and will ultimately help foster a relationship-centered PCMH.

Implementing the patient-centered medical home in complex adaptive systems: Becoming a relationship-centered patient-centered medical home

PubMed Central

Flieger, Signe Peterson

2017-01-01

Background This study explores the implementation experience of nine primary care practices becoming patient-centered medical homes (PCMH) as part of the New Hampshire Citizens Health Initiative Multi-Stakeholder Medical Home Pilot. Purpose The purpose of this study is to apply complex adaptive systems theory and relationship-centered organizations theory to explore how nine diverse primary care practices in New Hampshire implemented the PCMH model and to offer insights for how primary care practices can move from a structural PCMH to a relationship-centered PCMH. Methodology/Approach Eighty-three interviews were conducted with administrative and clinical staff at the nine pilot practices, payers, and conveners of the pilot between November and December 2011. The interviews were transcribed, coded, and analyzed using both a priori and emergent themes. Findings Although there is value in the structural components of the PCMH (e.g., disease registries), these structures are not enough. Becoming a relationship-centered PCMH requires attention to reflection, sensemaking, learning, and collaboration. This can be facilitated by settings aside time for communication and relationship building through structured meetings about PCMH components as well as the implementation process itself. Moreover, team-based care offers a robust opportunity to move beyond the structures to focus on relationships and collaboration. Practice Implications (a) Recognize that PCMH implementation is not a linear process. (b) Implementing the PCMH from a structural perspective is not enough. Although the National Committee for Quality Assurance or other guidelines can offer guidance on the structural components of PCMH implementation, this should serve only as a starting point. (c) During implementation, set aside structured time for reflection and sensemaking. (d) Use team-based care as a cornerstone of transformation. Reflect on team structures and also interactions of the team members. Taking the time to reflect will facilitate greater sensemaking and learning and will ultimately help foster a relationship-centered PCMH. PMID:26939031

The landscape of fear as an emergent property of heterogeneity: Contrasting patterns of predation risk in grassland ecosystems.

PubMed

Atuo, Fidelis Akunke; O'Connell, Timothy John

2017-07-01

The likelihood of encountering a predator influences prey behavior and spatial distribution such that non-consumptive effects can outweigh the influence of direct predation. Prey species are thought to filter information on perceived predator encounter rates in physical landscapes into a landscape of fear defined by spatially explicit heterogeneity in predation risk. The presence of multiple predators using different hunting strategies further complicates navigation through a landscape of fear and potentially exposes prey to greater risk of predation. The juxtaposition of land cover types likely influences overlap in occurrence of different predators, suggesting that attributes of a landscape of fear result from complexity in the physical landscape. Woody encroachment in grasslands furnishes an example of increasing complexity with the potential to influence predator distributions. We examined the role of vegetation structure on the distribution of two avian predators, Red-tailed Hawk ( Buteo jamaicensis ) and Northern Harrier ( Circus cyaneus ), and the vulnerability of a frequent prey species of those predators, Northern Bobwhite ( Colinus virginianus ). We mapped occurrences of the raptors and kill locations of Northern Bobwhite to examine spatial vulnerability patterns in relation to landscape complexity. We use an offset model to examine spatially explicit habitat use patterns of these predators in the Southern Great Plains of the United States, and monitored vulnerability patterns of their prey species based on kill locations collected during radio telemetry monitoring. Both predator density and predation-specific mortality of Northern Bobwhite increased with vegetation complexity generated by fine-scale interspersion of grassland and woodland. Predation pressure was lower in more homogeneous landscapes where overlap of the two predators was less frequent. Predator overlap created areas of high risk for Northern Bobwhite amounting to 32% of the land area where landscape complexity was high and 7% where complexity was lower. Our study emphasizes the need to evaluate the role of landscape structure on predation dynamics and reveals another threat from woody encroachment in grasslands.

Use of complex adaptive systems metaphor to achieve professional and organizational change.

PubMed

Rowe, Ann; Hogarth, Annette

2005-08-01

This paper uses the experiences of a programme designed to bring about change in performance of public health nurses (health visitors and school nurses) in an inner city primary care trust, to explore the issues of professional and organizational change in health care organizations. The United Kingdom government has given increasing emphasis to programmes of modernization within the National Health Service. A central facet of this policy shift has been an expectation of behaviour and practice change by health care professionals. Change was brought about through use of a Complex Adaptive Systems approach. This enabled change to be seen as an inclusive, evolving and unpredictable process rather one which is linear and mechanistic. The paper examines in detail how the use of concepts and metaphors associated with Complex Adaptive Systems influenced the development of the programme, its implementation and outcomes. The programme resulted in extensive change in professional behaviour, service delivery and transformational change in the organizational structures and processes of the employing organization. This gave greater opportunities for experimentation and innovation, leading to new developments in service delivery, but also meant higher levels of uncertainty, responsibility, decision-making and risk management for practitioners. Using a Complex Adaptive Systems approach was helpful for developing alternative views of change and for understanding why and how some aspects of change were more successful than others. Its use encouraged the confrontation of some long-standing assumptions about change and service delivery patterns in the National Health Service, and the process exposed challenging tensions within the Service. The consequent destabilising of organizational and professional norms resulted in considerable emotional impacts for practitioners, an area which was found to be underplayed within the Complex Adaptive Systems literature. A Complex Adaptive Systems approach can support change, in particular a recognition and understanding of the emergence of unexpected structures, patterns and processes. The approach can support nurses to change their behaviour and innovate, but requires high levels of accountability, individual and professional creativity.

DNA-based construction at the nanoscale: emerging trends and applications

NASA Astrophysics Data System (ADS)

Lourdu Xavier, P.; Chandrasekaran, Arun Richard

2018-02-01

The field of structural DNA nanotechnology has evolved remarkably—from the creation of artificial immobile junctions to the recent DNA-protein hybrid nanoscale shapes—in a span of about 35 years. It is now possible to create complex DNA-based nanoscale shapes and large hierarchical assemblies with greater stability and predictability, thanks to the development of computational tools and advances in experimental techniques. Although it started with the original goal of DNA-assisted structure determination of difficult-to-crystallize molecules, DNA nanotechnology has found its applications in a myriad of fields. In this review, we cover some of the basic and emerging assembly principles: hybridization, base stacking/shape complementarity, and protein-mediated formation of nanoscale structures. We also review various applications of DNA nanostructures, with special emphasis on some of the biophysical applications that have been reported in recent years. In the outlook, we discuss further improvements in the assembly of such structures, and explore possible future applications involving super-resolved fluorescence, single-particle cryo-electron (cryo-EM) and x-ray free electron laser (XFEL) nanoscopic imaging techniques, and in creating new synergistic designer materials.

Implicit Learning of Recursive Context-Free Grammars

PubMed Central

Rohrmeier, Martin; Fu, Qiufang; Dienes, Zoltan

2012-01-01

Context-free grammars are fundamental for the description of linguistic syntax. However, most artificial grammar learning experiments have explored learning of simpler finite-state grammars, while studies exploring context-free grammars have not assessed awareness and implicitness. This paper explores the implicit learning of context-free grammars employing features of hierarchical organization, recursive embedding and long-distance dependencies. The grammars also featured the distinction between left- and right-branching structures, as well as between centre- and tail-embedding, both distinctions found in natural languages. People acquired unconscious knowledge of relations between grammatical classes even for dependencies over long distances, in ways that went beyond learning simpler relations (e.g. n-grams) between individual words. The structural distinctions drawn from linguistics also proved important as performance was greater for tail-embedding than centre-embedding structures. The results suggest the plausibility of implicit learning of complex context-free structures, which model some features of natural languages. They support the relevance of artificial grammar learning for probing mechanisms of language learning and challenge existing theories and computational models of implicit learning. PMID:23094021

DNA-based construction at the nanoscale: emerging trends and applications.

PubMed

Xavier, P Lourdu; Chandrasekaran, Arun Richard

2018-02-09

The field of structural DNA nanotechnology has evolved remarkably-from the creation of artificial immobile junctions to the recent DNA-protein hybrid nanoscale shapes-in a span of about 35 years. It is now possible to create complex DNA-based nanoscale shapes and large hierarchical assemblies with greater stability and predictability, thanks to the development of computational tools and advances in experimental techniques. Although it started with the original goal of DNA-assisted structure determination of difficult-to-crystallize molecules, DNA nanotechnology has found its applications in a myriad of fields. In this review, we cover some of the basic and emerging assembly principles: hybridization, base stacking/shape complementarity, and protein-mediated formation of nanoscale structures. We also review various applications of DNA nanostructures, with special emphasis on some of the biophysical applications that have been reported in recent years. In the outlook, we discuss further improvements in the assembly of such structures, and explore possible future applications involving super-resolved fluorescence, single-particle cryo-electron (cryo-EM) and x-ray free electron laser (XFEL) nanoscopic imaging techniques, and in creating new synergistic designer materials.

Lightweight composite reflectors for space optics

NASA Astrophysics Data System (ADS)

Williams, Brian E.; McNeal, Shawn R.; Ono, Russell M.

1998-01-01

The primary goal of this work was to advance the state of the art in lightweight, high optical quality reflectors for space- and Earth-based telescopes. This was accomplished through the combination of a precision silicon carbide (SiC) reflector surface and a high specific strength, low-mass SiC structural support. Reducing the mass of components launched into space can lead to substantial cost savings, but an even greater benefit of lightweight reflectors for both space- and Earth-based optics applications is the fact that they require far less complex and less expensive positioning systems. While Ultramet is not the first company to produce SiC by chemical vapor deposition (CVD) for reflector surfaces, it is the first to propose and demonstrate a lightweight, open-cell SiC structural foam that can support a thin layer of the highly desirable polished SiC reflector material. SiC foam provides a substantial structural and mass advantage over conventional honeycomb supports and alternative finned structures. The result is a reflector component that meets or exceeds the optical properties of current high-quality glass, ceramic, and metal reflectors while maintaining a substantially lower areal density.

The radiometal makes a difference. Synthesis and preliminary characterisation of DOTA-minigastrin analogue complexes with Ga, Lu and Y.

PubMed

Maurin, Michał; Garnuszek, Piotr; Baran, Piotr; Pawlak, Dariusz; Mikołajczak, Renata

2015-01-01

The minigastrin analogue - CP04: DOTA-(DGlu)6-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2 has been developed for CCK2R targeting. This analogue can be radiolabelled with 111In or 68Ga for imaging, or with 90Y and 177Lu for therapy. However, affinity of the chelator-peptide conjugates to the cell membrane receptors may vary depending on the metal incorporated into the complex. So far, there are no such studies for the ligands of gastrin/cholecystokinin receptor CCK2R. It is supposed that the reason for the differentiation of receptor affinity to the respective receptors is in the changes of structure of chelating system and their influence on the bioactive conformations of the metal conjugated peptides. Herein, we report on the radiolabeling of CP04 with 90Y, 177Lu and 68Ga and synthesis of cold CP04 complexes with respective stable metals for further structural and physico-chemical and biological studies. From 200 to 600 MBq of 90Y, 177Lu or 68Ga were used for radiolabelling of 20 μg of CP04 dissolved in ascorbic acid solution (50 mg/mL, pH 4.5). Non-radioactive complexes with Lu and Ga were synthesized in milligram amounts starting from 0.5 mg up to 5 mg of CP04 dissolved in ascorbic acid solution (50 mg/mL, pH 4.5) when using 2-molar excess of the metal ions. Complex formation needed 5 min in microwave oven or 12 min in thermo-block at 95°C. RP-HPLC isocratic method (Kinetex 150/4.6 mm; 25% AcN/0.1% TFA, 1 mL/min) with UV/Vis and radiometric detection was developed for investigation of the radiolabelled and "cold" complexes. For LC-MS investigations, HPLC method was modified replacing TFA by formic acid. Yields of CP04 radiolabelling were greater than 90% for all three radionuclides. The HPLC method enabled identification of these radio-complexes based on comparison to their non-radioactive equivalents. In all cases, chromatograms revealed peaks that could be attributed to the metal-CP04 complexes and to impurities (including methionine oxidation). LC-MS analysis of Ga and Lu complexes revealed conformity of the observed molecular ions to the predicted formulas (m/z 2116 and 2220 Da for Ga and Lu, respectively). Different chromatographic behaviour observed for Ga-CP04 complex comparing to Lu- and Y- labelled peptide (relative retention to CP04: 1.08, 0.86 and 0.85, respectively) suggest different coordination of the metal ions. Therefore, further studies are planned using the non-radioactive complexes in order to assess their structural conformations.

Thermostability of photosystem I trimers and monomers from the cyanobacterium Thermosynechococcus elongatus

NASA Astrophysics Data System (ADS)

Shubin, Vladimir V.; Terekhova, Irina V.; Bolychevtseva, Yulia V.; El-Mohsnawy, Eithar; Rögner, Matthias; Mäntele, Werner; Kopczak, Marta J.; Džafić, Enela

2017-05-01

The performance of solar energy conversion into alternative energy sources in artificial systems highly depends on the thermostability of photosystem I (PSI) complexes Terasaki et al. (2007), Iwuchukwu et al. (2010), Kothe et al. (2013) . To assess the thermostability of PSI complexes from the thermophilic cyanobacterium Thermosynechococcus elongatus heating induced perturbations on the level of secondary structure of the proteins were studied. Changes were monitored by Fourier transform infrared (FT-IR) spectra in the mid-IR region upon slow heating (1 °C per minute) of samples in D2O phosphate buffer (pD 7.4) from 20 °C to 100 °C. These spectra showed distinct changes in the Amide I region of PSI complexes as a function of the rising temperature. Absorbance at the Amide I maximum of PSI monomers (centered around 1653 cm- 1), gradually dropped in two temperature intervals, i.e. 60-75 and 80-90 °C. In contrast, absorbance at the Amide I maximum of PSI trimers (around 1656 cm- 1) dropped only in one temperature interval 80-95 °C. The thermal profile of the spectral shift of α-helices bands in the region 1656-1642 cm- 1 confirms the same two temperature intervals for PSI monomers and only one interval for trimers. Apparently, the observed absorbance changes at the Amide I maximum during heating of PSI monomers and trimers are caused by deformation and unfolding of α-helices. The absence of absorbance changes in the interval of 20-65 °C in PSI trimers is probably caused by a greater stability of protein secondary structure as compared to that in monomers. Upon heating above 80 °C a large part of α-helices both in trimers and monomers converts to unordered and aggregated structures. Spectral changes of PSI trimers and monomers heated up to 100 °C are irreversible due to protein denaturation and non-specific aggregation of complexes leading to new absorption bands at 1618-1620 cm- 1. We propose that monomers shield the denaturation sensitive sides at the monomer/monomer interface within a trimer, making the oligomeric structure more stable against thermal stress.

Extensive massive basal-ice structures in West Antarctica relate to ice-sheet anisotropy and ice-flow

NASA Astrophysics Data System (ADS)

Ross, N.; Bingham, R. G.; Corr, H. F. J.; Siegert, M. J.

2016-12-01

Complex structures identified within both the East Antarctic and Greenland ice sheets are thought to be generated by the action of basal water freezing to the ice-sheet base, evolving under ice flow. Here, we use ice-penetrating radar to image an extensive series of similarly complex basal ice facies in West Antarctica, revealing a thick (>500 m) tectonised unit in an area of cold-based and relatively slow-flowing ice. We show that major folding and overturning of the unit perpendicular to ice flow elevates deep, warm ice into the mid ice-sheet column. Fold axes align with present ice flow, and axis amplitudes increase down-ice, suggesting long-term consistency in the direction and convergence of flow. In the absence of basal water, and the draping of the tectonised unit over major subglacial mountain ranges, the formation of the unit must be solely through the deformation of meteoric ice. Internal layer radar reflectivity is consistently greater parallel to flow compared with the perpendicular direction, revealing ice-sheet crystal anisotropy is associated with the folding. By linking layers to the Byrd ice-core site, we show the basal ice dates to at least the last glacial cycle and may be as old as the last interglacial. Deformation of deep-ice in this sector of WAIS, and potentially elsewhere in Antarctica, may be caused by differential shearing at interglacial-glacial boundaries, in a process analogous to that proposed for interior Greenland. The scale and heterogeneity of the englacial structures, and their subsequent impact on ice sheet rheology, means that the nature of ice flow across the bulk of West Antarctica must be far more complex that is currently accounted for by any numerical ice sheet model.

Interaction of Merocyanine 540 with serum albumins: photophysical and binding studies.

PubMed

Banerjee, Mousumi; Pal, Uttam; Subudhhi, Arijita; Chakrabarti, Abhijit; Basu, Samita

2012-03-01

Photophysical studies on binding interactions of a negatively charged anti-tumor photosensitizer, Merocyanine 540 (MC 540), with serum proteins, bovine serum albumin (BSA) and human serum albumin (HSA), have been performed using absorption and steady-state as well as time-resolved fluorescence techniques. Formation of ground state complex has been confirmed from the detailed studies of absorption spectra of MC 540 in presence of SAs producing isosbestic points. Binding between the proteins and MC 540, which perturbs the existing equilibrium between the fluorescent monomer and its non-fluorescent dimer, induces a remarkable enhancement in fluorescence anisotropy and intensity of MC 540 along with a red shift of its maximum. The binding stoichiometry of MC 540 and SAs are more than 1.0 which depicts that two types of complexes, i.e., 1:1 and 2:1 are formed with addition of varied concentration of protein. Both the steady-state and time-resolved fluorescence results show that in 2:1 complex one of the MC 540 molecules is exposed towards aqueous environment with a greater extent when bound with HSA compared to BSA due to the structural flexibility of that protein. Thermodynamic analyses using van't Hoff plot indicate that the binding between MC 540 and individual SA is an entropy-driven phenomenon. The probable hydrophobic binding site has been located by denaturation of proteins, micropolarity measurement and Förster resonance energy transfer and that is further supported by molecular docking studies. Changes in circular dichroism spectra of BSA in presence of MC 540 depict secondary structural changes of the protein. The induced-CD shows that BSA due to its rigid structure generates chirality in MC 540 much more efficiently compared to HSA. Copyright © 2011 Elsevier B.V. All rights reserved.

Structure and magnetic properties of an unprecedented syn-anti μ-nitrito-1κO:2κO' bridged Mn(III)-salen complex and its isoelectronic and isostructural formate analogue.

PubMed

Kar, Paramita; Biswas, Rituparna; Drew, Michael G B; Ida, Yumi; Ishida, Takayuki; Ghosh, Ashutosh

2011-04-07

The preparation, crystal structures and magnetic properties of two new isoelectronic and isomorphous formate- and nitrite-bridged 1D chains of Mn(III)-salen complexes, [Mn(salen)(HCOO)](n) (1) and [Mn(salen)(NO(2))](n) (2), where salen is the dianion of N,N'-bis(salicylidene)-1,2-diaminoethane, are presented. The structures show that the salen ligand coordinates to the four equatorial sites of the metal ion and the formate or nitrite ions coordinate to the axial positions to bridge the Mn(III)-salen units through a syn-antiμ-1κO:2κO' coordination mode. Such a bridging mode is unprecedented in Mn(III) for formate and in any transition metal ion for nitrite. Variable-temperature magnetic susceptibility measurements of complexes 1 and 2 indicate the presence of ferromagnetic exchange interactions with J values of 0.0607 cm(-1) (for 1) and 0.0883 cm(-1) (for 2). The ac measurements indicate negligible frequency dependence for 1 whereas compound 2 exhibits a decrease of χ(ac)' and a concomitant increase of χ(ac)'' on elevating frequency around 2 K. This finding is an indication of slow magnetization reversal characteristic of single-chain magnets or spin-glasses. The μ-nitrito-1κO:2κO' bridge seems to be a potentially superior magnetic coupler to the formate bridge for the construction of single-molecule/-chain magnets as its coupling constant is greater and the χ(ac)' and χ(ac)'' show frequency dependence. © The Royal Society of Chemistry 2011

Surface-Sensitive Microwear Texture Analysis of Attrition and Erosion.

PubMed

Ranjitkar, S; Turan, A; Mann, C; Gully, G A; Marsman, M; Edwards, S; Kaidonis, J A; Hall, C; Lekkas, D; Wetselaar, P; Brook, A H; Lobbezoo, F; Townsend, G C

2017-03-01

Scale-sensitive fractal analysis of high-resolution 3-dimensional surface reconstructions of wear patterns has advanced our knowledge in evolutionary biology, and has opened up opportunities for translatory applications in clinical practice. To elucidate the microwear characteristics of attrition and erosion in worn natural teeth, we scanned 50 extracted human teeth using a confocal profiler at a high optical resolution (X-Y, 0.17 µm; Z < 3 nm). Our hypothesis was that microwear complexity would be greater in erosion and that anisotropy would be greater in attrition. The teeth were divided into 4 groups, including 2 wear types (attrition and erosion) and 2 locations (anterior and posterior teeth; n = 12 for each anterior group, n = 13 for each posterior group) for 2 tissue types (enamel and dentine). The raw 3-dimensional data cloud was subjected to a newly developed rigorous standardization technique to reduce interscanner variability as well as to filter anomalous scanning data. Linear mixed effects (regression) analyses conducted separately for the dependent variables, complexity and anisotropy, showed the following effects of the independent variables: significant interactions between wear type and tissue type ( P = 0.0157 and P = 0.0003, respectively) and significant effects of location ( P < 0.0001 and P = 0.0035, respectively). There were significant associations between complexity and anisotropy when the dependent variable was either complexity ( P = 0.0003) or anisotropy ( P = 0.0014). Our findings of greater complexity in erosion and greater anisotropy in attrition confirm our hypothesis. The greatest geometric means were noted in dentine erosion for complexity and dentine attrition for anisotropy. Dentine also exhibited microwear characteristics that were more consistent with wear types than enamel. Overall, our findings could complement macrowear assessment in dental clinical practice and research and could assist in the early detection and management of pathologic tooth wear.

Multiheteromacrocycles that Complex Metal Ions. Second Progress Report, 1 May 1975 -- 30 April 1976

DOE R&D Accomplishments Database

Cram, D. J.

1976-01-15

Objective is to develop cyclic and polycyclic host organic compounds to complex and lipophilize metal ions. Macrorings were synthesized: (OCH{sub 2} CH{sub 2} O CH{sub 2}COCH{sub 2} COCH{sub 2}){sub 2} and (OCH{sub 2} CH{sub 2} O CH{sub 2} COCH{sub 2} COCH{sub 2}){sub 3}. The smaller ring complexes divalent metals 10{sup 1+9} times better than the open-chain model CH{sub 3} O CH{sub 2} CO CH{sub 2} COCH{sub 2} O CH{sub 3}, and the order in which metal ions are complexed is Cu{sup 2+}, UO{sub 2}{sup 2+} greater than Ni{sup 2+} greater than Fe{sup 2+}, Co{sup 2+}, Zn{sup 2+}, Cd{sup 2+} greater than Mn{sup 2+}. The UO{sub 2}{sup 2+} and Cu{sup 2+} complexes were isolated and characterized. The larger ring complexes trivalent metals 10{sup 0.9-1.7} times better than the open- chain model compound, and the order is La{sup 3+}, Ce{sup 3+} greater than Cr{sup 3+}. Five other macrocycles were also synthesized, and their binding constants with Na, K, NH{sub 4}, and Cs picrates were measured. Six compounds containing one macroring and two inward-pointing ArOH or ArOCH{sub 3} groups were also prepared and tested for binding of Li, Na, K, Rb, and NH{sub 4} picrates. Racemic compounds containing two binaphthyls and its sulfur analog were prepared. Cage-shaped multiheteromacrocycles containing ten O ligand sites or four S and six O ligand sites were prepared and the binding capability of the first compound for picrates studied. Two ring systems with phosphonate ester groups were also prepared. (DLC)

Identification of hierarchical chromatin domains

PubMed Central

Weinreb, Caleb; Raphael, Benjamin J.

2016-01-01

Motivation: The three-dimensional structure of the genome is an important regulator of many cellular processes including differentiation and gene regulation. Recently, technologies such as Hi-C that combine proximity ligation with high-throughput sequencing have revealed domains of self-interacting chromatin, called topologically associating domains (TADs), in many organisms. Current methods for identifying TADs using Hi-C data assume that TADs are non-overlapping, despite evidence for a nested structure in which TADs and sub-TADs form a complex hierarchy. Results: We introduce a model for decomposition of contact frequencies into a hierarchy of nested TADs. This model is based on empirical distributions of contact frequencies within TADs, where positions that are far apart have a greater enrichment of contacts than positions that are close together. We find that the increase in contact enrichment with distance is stronger for the inner TAD than for the outer TAD in a TAD/sub-TAD pair. Using this model, we develop the TADtree algorithm for detecting hierarchies of nested TADs. TADtree compares favorably with previous methods, finding TADs with a greater enrichment of chromatin marks such as CTCF at their boundaries. Availability and implementation: A python implementation of TADtree is available at http://compbio.cs.brown.edu/software/ Contact: braphael@cs.brown.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:26315910

Structural and Functional Basis for an EBNA1 Hexameric Ring in Epstein-Barr Virus Episome Maintenance.

PubMed

Deakyne, Julianna S; Malecka, Kimberly A; Messick, Troy E; Lieberman, Paul M

2017-10-01

Epstein-Barr virus (EBV) establishes a stable latent infection that can persist for the life of the host. EBNA1 is required for the replication, maintenance, and segregation of the latent episome, but the structural features of EBNA1 that confer each of these functions are not completely understood. Here, we have solved the X-ray crystal structure of an EBNA1 DNA-binding domain (DBD) and discovered a novel hexameric ring oligomeric form. The oligomeric interface pivoted around residue T585 as a joint that links and stabilizes higher-order EBNA1 complexes. Substitution mutations around the interface destabilized higher-order complex formation and altered the cooperative DNA-binding properties of EBNA1. Mutations had both positive and negative effects on EBNA1-dependent DNA replication and episome maintenance with OriP. We found that one naturally occurring polymorphism in the oligomer interface (T585P) had greater cooperative DNA binding in vitro , minor defects in DNA replication, and pronounced defects in episome maintenance. The T585P mutant was compromised for binding to OriP in vivo as well as for assembling the origin recognition complex subunit 2 (ORC2) and trimethylated histone 3 lysine 4 (H3K4me3) at OriP. The T585P mutant was also compromised for forming stable subnuclear foci in living cells. These findings reveal a novel oligomeric structure of EBNA1 with an interface subject to naturally occurring polymorphisms that modulate EBNA1 functional properties. We propose that EBNA1 dimers can assemble into higher-order oligomeric structures important for diverse functions of EBNA1. IMPORTANCE Epstein-Barr virus is a human gammaherpesvirus that is causally associated with various cancers. Carcinogenic properties are linked to the ability of the virus to persist in the latent form for the lifetime of the host. EBNA1 is a sequence-specific DNA-binding protein that is consistently expressed in EBV tumors and is the only viral protein required to maintain the viral episome during latency. The structural and biochemical mechanisms by which EBNA1 allows the long-term persistence of the EBV genome are currently unclear. Here, we have solved the crystal structure of an EBNA1 hexameric ring and characterized key residues in the interface required for higher-order complex formation and long-term plasmid maintenance. Copyright © 2017 American Society for Microbiology.

Working with complexity: experiences of caring for mothers seeking residential parenting services in New South Wales, Australia.

PubMed

Fowler, Cathrine; Schmied, Virginia; Dickinson, Marie; Dahlen, Hannah Grace

2017-02-01

To investigate staff perception of the changing complexity of mothers and infants admitted to two residential parenting services in New South Wales in the decade from 2005-2015. For many mothers with a young child, parenting is difficult and stressful. If parenting occurs within the context of anxiety, mental illness or abuse it often becomes a high-risk situation for the primary caregiver. Residential parenting services provide early nursing intervention before parenting problems escalate and require physical or mental health focused care. A qualitative descriptive design using semi-structured interview questions was used as phase three of a larger study. Data were gathered from 35 child and family health nurses and ten physicians during eight focus groups. Three main themes emerged: (1) dealing with complexity; (2) changing practice; and (3) appropriate knowledge and skills to handle greater complexity. There was a mix of participant opinions about the increasing complexity of the mothers presenting at residential parenting services during the past decade. Some of the nurses and physicians confirmed an increase in complexity of the mothers while several participants proposed that it was linked to their increased psychosocial assessment knowledge and skill. All participants recognised their work had grown in complexity regardless of their perception about the increased complexity of the mothers. Australian residential parenting services have a significant role in supporting mothers and their families who are experiencing parenting difficulties. It frequently provides early intervention that helps minimise later emotional and physical problems. Nurses are well placed to work with and support mothers with complex histories. Acknowledgement is required that this work is stressful and nurses need to be adequately supported and educated to manage the complex presentations of many families. © 2016 John Wiley & Sons Ltd.

Biomechanical study of patellofemoral joint instability

NASA Astrophysics Data System (ADS)

Senavongse, Wongwit

2005-04-01

Patellofemoral joint instability is a complex clinical problem. It may be a consequence of pre-existing anatomical abnormality or trauma. The objectives of this study were to use experimental mechanics to measure patellar stability and to quantify the effects of pathological abnormalities on patellar stability in vitro. Eight fresh-frozen cadaver knees were studies. The patellar stability was measured using an Instron material testing machine. A total load of 175N was applied to the quadriceps muscles. Patellar force-displacement was tested at different knee flexion angles as the patella was cyclically displaced 10mm laterally and medially. Three pathological abnormalities were applied; VMO malfunction, flat lateral trochlea, and medial retinacular structure rupturing. For the first time, this study has shown comparative and quantitative influence of pathological abnormalities on patellar stability. It was found that a flat lateral trochlea has greater effect than the medial retinacular rupturing whereas the medial retinacular rupturing has greater effect than VMO malfunction on patellar lateral stability. These results are important for future investigations on the treatment of patellofemoral instability.

Gender and the utilisation of health services in the Ashanti Region, Ghana.

PubMed

Buor, Daniel

2004-09-01

The survey seeks to structure a model for gender-based health services utilisation for the Ashanti Region of Ghana, and in addition, recommend intervention measures to ensure gender equity in the utilisation of health services. A sample size of 650 covered over 3108 houses, and the main research instruments were the questionnaire and formal interview. A multiple regression model is used for the analysis of the relationship between the complex independent variables and utilisation by gender. Results show that although females have a greater need for health services than males, they do not utilise health services as much. Secondly, whereas quality of service, health status, service cost and education have greater effect on male utilisation than females, distance and income have higher impact on female utilisation. It is recommended that, to ensure equity in health care utilisation, females be empowered through increased access to formal education and sustainable income opportunities. The introduction of a national health insurance scheme is also recommended to ensure adequate access by both sexes.

Phospholipids-embedded fully dilutable liquid nanostructures. Part 2: The role of sodium diclofenac.

PubMed

Amsalem, Orit; Aserin, Abraham; Garti, Nissim

2010-12-01

Complex pseudo-ternary phase diagrams based on sucrose monolaurate (SE), propylene glycol (PG), and phosphatidylcholine (PC) as the "surfactant phase"; triacetin (TA) and decaglycerol ester (10G1CC) as the "oil phase"; and water as the aqueous phase were constructed, into which we solubilized the water-insoluble drug (sodium diclofenac, Na-DFC). In our previous study we demonstrated that the solubilization of Na-DFC in the oil+surfactant phases (prior to diluting it with water), was 90-fold greater than its dissolution in water, and that the system was pH-dependent. The greatest Na-DFC solubilization capacity was obtained at pH 7.2. In this study we examined the effect of the solubilization of Na-DFC in a phosphatidylcholine system using DLS, viscosity, electrical conductivity, SAXS, SD-NMR, and cryo-TEM measurements. It was found that: (1) the system remains micellar after aqueous dilution but with greater polydispersity and greater variety of shapes. We concluded that the structures in the absence of water (but in the presence of PG) were of direct spherical micelles (∼4 nm) mixed with elongated cylindrical micelles (12-140 nm); (2) the aqueous dilution causes fragmentation of the cylinders into smaller spherical micelles; (3) solubilization of Na-DFC behaving like a kosmotropic agent or "structure maker" yields mostly spherical swollen micelles and more ordered systems than in its absence; and (4) Na-DFC is solubilized at the interface of the micelles without swelling the droplets. Copyright © 2010 Elsevier B.V. All rights reserved.

Do the Hard Things First: A Randomized Controlled Trial Testing the Effects of Exemplar Selection on Generalization Following Therapy for Grammatical Morphology

PubMed Central

Fey, Marc; Curran, Maura

2017-01-01

Purpose Complexity-based approaches to treatment have been gaining popularity in domains such as phonology and aphasia but have not yet been tested in child morphological acquisition. In this study, we examined whether beginning treatment with easier-to-inflect (easy first) or harder-to-inflect (hard first) verbs led to greater progress in the production of regular past-tense –ed by children with developmental language disorder. Method Eighteen children with developmental language disorder (ages 4–10) participated in a randomized controlled trial (easy first, N = 10, hard first, N = 8). Verbs were selected on the basis of frequency, phonological complexity, and telicity (i.e., the completedness of the event). Progress was measured by the duration of therapy, number of verb lists trained to criterion, and pre/post gains in accuracy for trained and untrained verbs on structured probes. Results The hard-first group made greater gains in accuracy on both trained and untrained verbs but did not have fewer therapy visits or train to criterion on more verb lists than the easy-first group. Treatment fidelity, average recasts per session, and verbs learned did not differ across conditions. Conclusion When targeting grammatical morphemes, it may be most efficient for clinicians to select harder rather than easier exemplars of the target. PMID:28796874

The Secretion of Oxygen into the Swim-Bladder of Fish

PubMed Central

Wittenberg, Jonathan B.; Schwend, Mary J.; Wittenberg, Beatrice A.

1964-01-01

The secretion of carbon dioxide accompanying the secretion of oxygen into the swim-bladder of the bluefish is examined in order to distinguish among several theories which have been proposed to describe the operation of the rete mirabile, a vascular countercurrent exchange organ. Carbon dioxide may comprise 27 per cent of the gas secreted, corresponding to a partial pressure of 275 mm Hg. This is greater than the partial pressure that would be generated by acidifying arterial blood (about 55 mm Hg). The rate of secretion is very much greater than the probable rate of metabolic formation of carbon dioxide in the gas-secreting complex. It is approximately equivalent to the probable rate of glycolytic generation of lactic acid in the gas gland. It is concluded that carbon dioxide brought into the swim-bladder is liberated from blood by the addition of lactic acid. The rete mirabile must act to multiply the primary partial pressure of carbon dioxide produced by acidification of the blood. The function of the rete mirabile as a countercurrent multiplier has been proposed by Kuhn, W., Ramel, A., Kuhn, H. J., and Marti, E., Experientia, 1963, 19, 497. Our findings provide strong support for their theory. The unique structure of the gas-secreting complex of the swim-bladder of the bluefish, Pomatomus saltatrix L., is described. PMID:14225261

THE SECRETION OF OXYGEN INTO THE SWIM-BLADDER OF FISH. 3. THE ROLE OF CARBON DIOXIDE.

PubMed

WITTENBERG, J B; SCHWEND, M J; WITTENBERG, B A

1964-11-01

The secretion of carbon dioxide accompanying the secretion of oxygen into the swim-bladder of the bluefish is examined in order to distinguish among several theories which have been proposed to describe the operation of the rete mirabile, a vascular countercurrent exchange organ. Carbon dioxide may comprise 27 per cent of the gas secreted, corresponding to a partial pressure of 275 mm Hg. This is greater than the partial pressure that would be generated by acidifying arterial blood (about 55 mm Hg). The rate of secretion is very much greater than the probable rate of metabolic formation of carbon dioxide in the gas-secreting complex. It is approximately equivalent to the probable rate of glycolytic generation of lactic acid in the gas gland. It is concluded that carbon dioxide brought into the swim-bladder is liberated from blood by the addition of lactic acid. The rete mirabile must act to multiply the primary partial pressure of carbon dioxide produced by acidification of the blood. The function of the rete mirabile as a countercurrent multiplier has been proposed by Kuhn, W., Ramel, A., Kuhn, H. J., and Marti, E., Experientia, 1963, 19, 497. Our findings provide strong support for their theory. The unique structure of the gas-secreting complex of the swim-bladder of the bluefish, Pomatomus saltatrix L., is described.

Modelling reef zonation in the Greater St Lucia Wetland Park, South Africa

NASA Astrophysics Data System (ADS)

Schleyer, Michael H.; Celliers, Louis

2005-05-01

East Africa has a rich coral fauna that extends to Maputaland in KwaZulu-Natal, South Africa. At this latitude, considered high and marginal for coral distribution and development, they form a veneer on limited, late Pleistocene reefs rather than forming the accretive, aragonite structures known as coral reefs. It is thus more appropriate to refer to them in this region as coral communities, the environment being rendered marginal for their development by reduced temperatures, light and aragonite saturation state. Subsequent to their discovery, the reefs were afforded protection within two Marine Protected Areas (the St Lucia and Maputaland Marine Reserves). They are found primarily within three reef complexes, with only the central complex being readily accessible to the public for ecotourism at present. With the creation of the Greater St Lucia Wetland Park, a World Heritage Site, and the expectation of an accompanying increase in ecotourism, the status quo seems set to change. The reefs are thus the current focus of a modelling initiative to provide decision support in their management. This paper examines the unique nature of the South African communities, their vulnerability and importance in the regional and global context, and, using representative data from the model, how an anticipated increase in their use could affect their sustainability. The case for scientifically based zonation for their use is presented.

Spatio-temporal Event Classification using Time-series Kernel based Structured Sparsity

PubMed Central

Jeni, László A.; Lőrincz, András; Szabó, Zoltán; Cohn, Jeffrey F.; Kanade, Takeo

2016-01-01

In many behavioral domains, such as facial expression and gesture, sparse structure is prevalent. This sparsity would be well suited for event detection but for one problem. Features typically are confounded by alignment error in space and time. As a consequence, high-dimensional representations such as SIFT and Gabor features have been favored despite their much greater computational cost and potential loss of information. We propose a Kernel Structured Sparsity (KSS) method that can handle both the temporal alignment problem and the structured sparse reconstruction within a common framework, and it can rely on simple features. We characterize spatio-temporal events as time-series of motion patterns and by utilizing time-series kernels we apply standard structured-sparse coding techniques to tackle this important problem. We evaluated the KSS method using both gesture and facial expression datasets that include spontaneous behavior and differ in degree of difficulty and type of ground truth coding. KSS outperformed both sparse and non-sparse methods that utilize complex image features and their temporal extensions. In the case of early facial event classification KSS had 10% higher accuracy as measured by F1 score over kernel SVM methods1. PMID:27830214

Directional selection can drive the evolution of modularity in complex traits

PubMed Central

Melo, Diogo; Marroig, Gabriel

2015-01-01

Modularity is a central concept in modern biology, providing a powerful framework for the study of living organisms on many organizational levels. Two central and related questions can be posed in regard to modularity: How does modularity appear in the first place, and what forces are responsible for keeping and/or changing modular patterns? We approached these questions using a quantitative genetics simulation framework, building on previous results obtained with bivariate systems and extending them to multivariate systems. We developed an individual-based model capable of simulating many traits controlled by many loci with variable pleiotropic relations between them, expressed in populations subject to mutation, recombination, drift, and selection. We used this model to study the problem of the emergence of modularity, and hereby show that drift and stabilizing selection are inefficient at creating modular variational structures. We also demonstrate that directional selection can have marked effects on the modular structure between traits, actively promoting a restructuring of genetic variation in the selected population and potentially facilitating the response to selection. Furthermore, we give examples of complex covariation created by simple regimes of combined directional and stabilizing selection and show that stabilizing selection is important in the maintenance of established covariation patterns. Our results are in full agreement with previous results for two-trait systems and further extend them to include scenarios of greater complexity. Finally, we discuss the evolutionary consequences of modular patterns being molded by directional selection. PMID:25548154

Directional selection can drive the evolution of modularity in complex traits.

PubMed

Melo, Diogo; Marroig, Gabriel

2015-01-13

Modularity is a central concept in modern biology, providing a powerful framework for the study of living organisms on many organizational levels. Two central and related questions can be posed in regard to modularity: How does modularity appear in the first place, and what forces are responsible for keeping and/or changing modular patterns? We approached these questions using a quantitative genetics simulation framework, building on previous results obtained with bivariate systems and extending them to multivariate systems. We developed an individual-based model capable of simulating many traits controlled by many loci with variable pleiotropic relations between them, expressed in populations subject to mutation, recombination, drift, and selection. We used this model to study the problem of the emergence of modularity, and hereby show that drift and stabilizing selection are inefficient at creating modular variational structures. We also demonstrate that directional selection can have marked effects on the modular structure between traits, actively promoting a restructuring of genetic variation in the selected population and potentially facilitating the response to selection. Furthermore, we give examples of complex covariation created by simple regimes of combined directional and stabilizing selection and show that stabilizing selection is important in the maintenance of established covariation patterns. Our results are in full agreement with previous results for two-trait systems and further extend them to include scenarios of greater complexity. Finally, we discuss the evolutionary consequences of modular patterns being molded by directional selection.

Predator behaviour and predation risk in the heterogeneous Arctic environment.

PubMed

Lecomte, Nicolas; Careau, Vincent; Gauthier, Gilles; Giroux, Jean-François

2008-05-01

1. Habitat heterogeneity and predator behaviour can strongly affect predator-prey interactions but these factors are rarely considered simultaneously, especially when systems encompass multiple predators and prey. 2. In the Arctic, greater snow geese Anser caerulescens atlanticus L. nest in two structurally different habitats: wetlands that form intricate networks of water channels, and mesic tundra where such obstacles are absent. In this heterogeneous environment, goose eggs are exposed to two types of predators: the arctic fox Vulpes lagopus L. and a diversity of avian predators. We hypothesized that, contrary to birds, the hunting ability of foxes would be impaired by the structurally complex wetland habitat, resulting in a lower predation risk for goose eggs. 3. In addition, lemmings, the main prey of foxes, show strong population cycles. We thus further examined how their fluctuations influenced the interaction between habitat heterogeneity and fox predation on goose eggs. 4. An experimental approach with artificial nests suggested that foxes were faster than avian predators to find unattended goose nests in mesic tundra whereas the reverse was true in wetlands. Foxes spent 3.5 times more time between consecutive attacks on real goose nests in wetlands than in mesic tundra. Their attacks on goose nests were also half as successful in wetlands than in mesic tundra whereas no difference was found for avian predators. 5. Nesting success in wetlands (65%) was higher than in mesic tundra (56%) but the difference between habitats increased during lemming crashes (15%) compared to other phases of the cycle (5%). Nests located at the edge of wetland patches were also less successful than central ones, suggesting a gradient in accessibility of goose nests in wetlands for foxes. 6. Our study shows that the structural complexity of wetlands decreases predation risk from foxes but not avian predators in arctic-nesting birds. Our results also demonstrate that cyclic lemming populations indirectly alter the spatial distribution of productive nests due to a complex interaction between habitat structure, prey-switching and foraging success of foxes.

Effect of Mechanical Heterogeneity on the Crack Driving Force of a Reactor Pressure Vessel Outlet Nozzle DMW Joint

NASA Astrophysics Data System (ADS)

Lingyan, Zhao; Yinghao, Cui; He, Xue

2017-12-01

The welding mechanical heterogeneity, load complexity, material and geometrical structure makes it very difficult to assess the structural integrity of dissimilar metal weld (DMW) joints. Based on a numerical simulated approach of the continuous change of material mechanical property in the buttering layer, a reactor pressure vessel (RPV) outlet nozzle DMW joint with service loads is studied, effect of mechanical heterogeneity on the stress-strain field and stress triaxiality at the semi-elliptical surface crack front are discussed. The analyses show that once the crack extends into the high hardness zone of Alloy 182 buttering, the strain decreases sharply, the strain gradient increases and the crack propagation slows down. The influence of strength mismatch on the stress triaxiality at the shallow crack front is greater than that at the deep crack front. The interaction between strength mismatch and crack depth directly affects the crack growth direction.

The effect of temperature on amount and structure of motor variability during 2-minute maximum voluntary contraction.

PubMed

Brazaitis, Marius; Skurvydas, Albertas; Pukėnas, Kazimieras; Daniuseviciūtė, Laura; Mickevicienė, Dalia; Solianik, Rima

2012-11-01

In this study, we questioned whether local cooling of muscle or heating involving core and muscle temperatures are the main indicators for force variability. Ten volunteers performed a 2-min maximum voluntary contraction (MVC) of the knee extensors under control (CON) conditions after passive heating (HT) and cooling (CL) of the lower body. HT increased muscle and rectal temperatures, whereas CL lowered muscle temperature but did not affect rectal temperature. During 2-min MVC, peak force decreased to a lower level in HT compared with CON and CL experiments. Greater central fatigue was found in the HT experiment, and there was less in the CL experiment than in the CON experiment. Increased core and muscle temperature increased physiological tremor and the amount and structural complexity of force variability of the exercising muscles, whereas local muscle cooling decreased all force variability variables measured. Copyright © 2012 Wiley Periodicals, Inc.

A project management system for the X-29A flight test program

NASA Technical Reports Server (NTRS)

Stewart, J. F.; Bauer, C. A.

1983-01-01

The project-management system developed for NASA's participation in the X-29A aircraft development program is characterized from a theoretical perspective, as an example of a system appropriate to advanced, highly integrated technology projects. System-control theory is applied to the analysis of classical project-management techniques and structures, which are found to be of closed-loop multivariable type; and the effects of increasing project complexity and integration are evaluated. The importance of information flow, sampling frequency, information holding, and delays is stressed. The X-29A system is developed in four stages: establishment of overall objectives and requirements, determination of information processes (block diagrams) definition of personnel functional roles and relationships, and development of a detailed work-breakdown structure. The resulting system is shown to require a greater information flow to management than conventional methods. Sample block diagrams are provided.

Role of random electric fields in relaxors

PubMed Central

Phelan, Daniel; Stock, Christopher; Rodriguez-Rivera, Jose A.; Chi, Songxue; Leão, Juscelino; Long, Xifa; Xie, Yujuan; Bokov, Alexei A.; Ye, Zuo-Guang; Ganesh, Panchapakesan; Gehring, Peter M.

2014-01-01

PbZr1–xTixO3 (PZT) and Pb(Mg1/3Nb2/3)1–xTixO3 (PMN-xPT) are complex lead-oxide perovskites that display exceptional piezoelectric properties for pseudorhombohedral compositions near a tetragonal phase boundary. In PZT these compositions are ferroelectrics, but in PMN-xPT they are relaxors because the dielectric permittivity is frequency dependent and exhibits non-Arrhenius behavior. We show that the nanoscale structure unique to PMN-xPT and other lead-oxide perovskite relaxors is absent in PZT and correlates with a greater than 100% enhancement of the longitudinal piezoelectric coefficient in PMN-xPT relative to that in PZT. By comparing dielectric, structural, lattice dynamical, and piezoelectric measurements on PZT and PMN-xPT, two nearly identical compounds that represent weak and strong random electric field limits, we show that quenched (static) random fields establish the relaxor phase and identify the order parameter. PMID:24449912

Thinking Styles and Quality of University Life Among Deaf or Hard of Hearing and Hearing Students.

PubMed

Cheng, Sanyin; Zhang, Li-Fang

2017-01-01

The authors explored how thinking styles relate to quality of university life among deaf or hard of hearing (DHH) and hearing university students in mainland China. The first of two studies affirmed the validity and reliability of a modified version of the Quality of University Life Measure (QULM; Sirgy, Grezskowiak, & Rahtz, 2007) among 833 university students (366 DHH, 467 hearing). The second investigated relationships between thinking styles and quality of university life; the Thinking Styles Inventory-Revised II (Sternberg, Wagner, & Zhang, 2007) and modified QULM were administered to 542 students (256 DHH, 286 hearing). Students scoring higher on Type I styles (i.e., more creativity-generating, less structured, cognitively more complex) tended toward greater satisfaction with university life; those scoring higher on Type II (i.e., more norm-favoring, more structured, cognitively more simplistic) tended toward less satisfaction. Contributions, limitations, and implications of the research are discussed.

Managing a big ground-based astronomy project: the Thirty Meter Telescope (TMT) project

NASA Astrophysics Data System (ADS)

Sanders, Gary H.

2008-07-01

TMT is a big science project and its scale is greater than previous ground-based optical/infrared telescope projects. This paper will describe the ideal "linear" project and how the TMT project departs from that ideal. The paper will describe the needed adaptations to successfully manage real world complexities. The progression from science requirements to a reference design, the development of a product-oriented Work Breakdown Structure (WBS) and an organization that parallels the WBS, the implementation of system engineering, requirements definition and the progression through Conceptual Design to Preliminary Design will be summarized. The development of a detailed cost estimate structured by the WBS, and the methodology of risk analysis to estimate contingency fund requirements will be summarized. Designing the project schedule defines the construction plan and, together with the cost model, provides the basis for executing the project guided by an earned value performance measurement system.

Water Ice Clouds and Dust in the Martian Atmosphere Observed by Mars Climate Sounder

NASA Technical Reports Server (NTRS)

Benson, Jennifer L.; Kass, David; Heavens, Nicholas; Kleinbohl, Armin

2011-01-01

The water ice clouds are primarily controlled by the temperature structure and form at the water condensation level. Clouds in all regions presented show day/night differences. Cloud altitude varies between night and day in the SPH and tropics: (1) NPH water ice opacity is greater at night than day at some seasons (2) The diurnal thermal tide controls the daily variability. (3) Strong day/night changes indicate that the amount of gas in the atmosphere varies significantly. See significant mixtures of dust and ice at the same altitude planet-wide (1) Points to a complex radiative and thermal balance between dust heating (in the visible) and ice heating or cooling in the infrared. Aerosol layering: (1) Early seasons reveal a zonally banded spatial distribution (2) Some localized longitudinal structure of aerosol layers (3) Later seasons show no consistent large scale organization

Musical Creativity “Revealed” in Brain Structure: Interplay between Motor, Default Mode, and Limbic Networks

PubMed Central

Bashwiner, David M.; Wertz, Christopher J.; Flores, Ranee A.; Jung, Rex E.

2016-01-01

Creative behaviors are among the most complex that humans engage in, involving not only highly intricate, domain-specific knowledge and skill, but also domain-general processing styles and the affective drive to create. This study presents structural imaging data indicating that musically creative people (as indicated by self-report) have greater cortical surface area or volume in a) regions associated with domain-specific higher-cognitive motor activity and sound processing (dorsal premotor cortex, supplementary and pre-supplementary motor areas, and planum temporale), b) domain-general creative-ideation regions associated with the default mode network (dorsomedial prefrontal cortex, middle temporal gyrus, and temporal pole), and c) emotion-related regions (orbitofrontal cortex, temporal pole, and amygdala). These findings suggest that domain-specific musical expertise, default-mode cognitive processing style, and intensity of emotional experience might all coordinate to motivate and facilitate the drive to create music. PMID:26888383

The transformation of housing and household structures in France and Great Britain.

PubMed

Bonvalet, C; Lelievre, E

1997-09-01

"In France and Great Britain, the last 30 years have seen considerable evolution in the housing stock...and in household structure....This article describes the dynamic interaction of processes influencing the evolution of both households and dwellings. In the two countries, the life course of individuals has become more and more complex. This translates into an ever greater variety of housing needs, not only at different stages in family life, but also in relation to growing job insecurity regardless of family situation. At the same time, policies encouraging home-ownership seem to have reached their limits, because of the new demand for rented accommodation. The answer to sociological and economic evolution cannot be found in a ¿single' type of housing and tenure status, but rather in a wide range of dwellings and in the development of a more flexible housing market." excerpt

Developing structure-activity relationships from an HTS hit for inhibition of the Cks1-Skp2 protein-protein interaction.

PubMed

Singh, Rajinder; Sran, Arvinder; Carroll, David C; Huang, Jianing; Tsvetkov, Lyuben; Zhou, Xiulan; Sheung, Julie; McLaughlin, John; Issakani, Sarkiz D; Payan, Donald G; Shaw, Simon J

2015-11-15

Structure-activity relationships have been developed around 5-bromo-8-toluylsulfonamidoquinoline 1 a hit compound in an assay for the interaction of the E3 ligase Skp2 with Cks1, part of the SCF ligase complex. Disruption of this protein-protein interaction results in higher levels of CDK inhibitor p27, which can act as a tumor suppressor. The results of the SAR developed highlight the relationship between the sulfonamide and quinoline nitrogen, while also suggesting that an aryl substituent at the 5-position of the quinoline ring contributes to the potency in the interaction assay. Compounds showing potency in the interaction assay result in greater levels of p27 and have been shown to inhibit cell growth of two p27 sensitive tumor cell lines. Copyright © 2015 Elsevier Ltd. All rights reserved.

A simulator for evaluating methods for the detection of lesion-deficit associations

NASA Technical Reports Server (NTRS)

Megalooikonomou, V.; Davatzikos, C.; Herskovits, E. H.

2000-01-01

Although much has been learned about the functional organization of the human brain through lesion-deficit analysis, the variety of statistical and image-processing methods developed for this purpose precludes a closed-form analysis of the statistical power of these systems. Therefore, we developed a lesion-deficit simulator (LDS), which generates artificial subjects, each of which consists of a set of functional deficits, and a brain image with lesions; the deficits and lesions conform to predefined distributions. We used probability distributions to model the number, sizes, and spatial distribution of lesions, to model the structure-function associations, and to model registration error. We used the LDS to evaluate, as examples, the effects of the complexities and strengths of lesion-deficit associations, and of registration error, on the power of lesion-deficit analysis. We measured the numbers of recovered associations from these simulated data, as a function of the number of subjects analyzed, the strengths and number of associations in the statistical model, the number of structures associated with a particular function, and the prior probabilities of structures being abnormal. The number of subjects required to recover the simulated lesion-deficit associations was found to have an inverse relationship to the strength of associations, and to the smallest probability in the structure-function model. The number of structures associated with a particular function (i.e., the complexity of associations) had a much greater effect on the performance of the analysis method than did the total number of associations. We also found that registration error of 5 mm or less reduces the number of associations discovered by approximately 13% compared to perfect registration. The LDS provides a flexible framework for evaluating many aspects of lesion-deficit analysis.

Structures and mechanisms in clay nanopore trapping of structurally-different fluoroquinolone antimicrobials.

PubMed

Okaikue-Woodi, Fanny E K; Kelch, Sabrina E; Schmidt, Michael P; Enid Martinez, Carmen; Youngman, Randall E; Aristilde, Ludmilla

2018-03-01

Smectite clay nanoparticles are implicated in the retention of antimicrobials within soils and sediments; these clays are also inspected as drug carriers in physiological systems. Cation exchange is considered the primary adsorption mechanism of antimicrobials within smectite nanopores. However, a dual role of acid-base chemistry and adsorptive structures is speculated by recent studies. Using the prototypical smectite clay montmorillonite, we employed a combination of X-ray diffraction (XRD), nuclear magnetic resonance, attenuated total reflectance-Fourier transform infrared spectroscopy, and molecular dynamics simulations to investigate the interlayer nanopore trapping of two structurally-different fluoroquinolone (FQ) antimicrobials with similar acid-base chemistry: ciprofloxacin (a first-generation FQ) and moxifloxacin (a third-generation FQ). Greater sorption at pH 5.0 than at pH 7.0 for both FQs was consistent with cation-exchange of positively-charged species. However, the clay exhibited a near twofold higher sorption capacity for moxifloxacin than for ciprofloxacin. This difference was shown by the XRD data to be accompanied by enhanced trapping of moxifloxacin within the clay interlayers. Using the XRD-determined nanopore sizes, we performed molecular dynamics simulations of thermodynamically-favorable model adsorbates, which revealed that ciprofloxacin was adsorbed parallel to the clay surface but moxifloxacin adopted a tilted conformation across the nanopore. These conformations resulted in more slowly-exchanged than quickly-exchanged Na complexes with ciprofloxacin compared with moxifloxacin. These different Na populations were also captured by 23 Na nuclear magnetic resonance. Furthermore, the simulated adsorbates uncovered different complexation interactions that were corroborated by infrared spectroscopy. Therefore, beyond acid-base chemistry, our findings imply that distinct adsorbate structures control antimicrobial trapping within clay nanopores, which can promote persistence in environmental matrices and stable delivery in biological systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Speaking under pressure: Low linguistic complexity is linked to high physiological and emotional stress reactivity

PubMed Central

Saslow, Laura R.; McCoy, Shannon; van der Löwe, Ilmo; Cosley, Brandon; Vartan, Arbi; Oveis, Christopher; Keltner, Dacher; Moskowitz, Judith T.; Epel, Elissa S.

2014-01-01

What can a speech reveal about someone's state? We tested the idea that greater stress reactivity would relate to lower linguistic cognitive complexity while speaking. In Study 1, we tested whether heart rate and emotional stress reactivity to a stressful discussion would relate to lower linguistic complexity. In Studies 2 and 3 we tested whether a greater cortisol response to a standardized stressful task including a speech (Trier Social Stress Test) would be linked to speaking with less linguistic complexity during the task. We found evidence that measures of stress responsivity (emotional and physiological) and chronic stress are tied to variability in the cognitive complexity of speech. Taken together, these results provide evidence that our individual experiences of stress or ‘stress signatures’—how our body and mind react to stress both in the moment and over the longer term—are linked to how complexly we speak under stress. PMID:24354732

Rearing environment influences boldness and prey acquisition behavior, and brain and lens development of bull trout

USGS Publications Warehouse

Brignon, William R.; Pike, Martin M.; Ebbesson, Lars O.E.; Schaller, Howard A.; Peterson, James T.; Schreck, Carl B.

2018-01-01

Animals reared in barren captive environments exhibit different developmental trajectories and behaviors than wild counterparts. Hence, the captive phenotypes may influence the success of reintroduction and recovery programs for threatened and endangered species. We collected wild bull trout embryos from the Metolius River Basin, Oregon and reared them in differing environments to better understand how captivity affects the bull trout Salvelinus confluentusphenotype. We compared the boldness and prey acquisition behaviors and development of the brain and eye lens of bull trout reared in conventional barren and more structurally complex captive environments with that of wild fish. Wild fish and captive reared fish from complex habitats exhibited a greater level of boldness and prey acquisition ability, than fish reared in conventional captive environments. In addition, the eye lens of conventionally reared bull trout was larger than complex reared captive fish or same age wild fish. Interestingly, we detected wild fish had a smaller relative cerebellum than either captive reared treatment. Our results suggest that rearing fish in more complex captive environments can create a more wild-like phenotype than conventional rearing practices. A better understanding of the effects of captivity on the development and behavior of bull trout can inform rearing and reintroduction programs though prediction of the performance of released individuals.

Exploiting single photon vacuum ultraviolet photoionization to unravel the synthesis of complex organic molecules in interstellar ices

NASA Astrophysics Data System (ADS)

Abplanalp, Matthew J.; Förstel, Marko; Kaiser, Ralf I.

2016-01-01

Complex organic molecules (COM) such as aldehydes, ketones, carboxylic acids, esters, and amides are ubiquitous in the interstellar medium, but traditional gas phase astrochemical models cannot explain their formation routes. By systematically exploiting on line and in situ vacuum ultraviolet photoionization coupled with reflectron time of flight mass spectrometry (PI-ReTOF-MS) and combining these data with infrared spectroscopy (FTIR), we reveal that complex organic molecules can be synthesized within interstellar ices that are condensed on interstellar grains via non-equilibrium reactions involving suprathermal hydrogen atoms at temperatures as low as 5 K. By probing for the first time specific structural isomers without their degradation (fragment-free), the incorporation of tunable vacuum ultraviolet photoionization allows for a much greater understanding of reaction mechanisms that exist in interstellar ices compared to traditional methods, thus eliminating the significant gap between observational and laboratory data that existed for the last decades. With the commission of the Atacama Large Millimeter/Submillimeter Array (ALMA), the number of detections of more complex organic molecules in space will continue to grow ⿿ including biorelevant molecules connected to the Origins of Life theme ⿿ and an understanding of these data will rely on future advances in sophisticated physical chemistry laboratory experiments.

Thiocyanate-Ligated Heterobimetallic {PtM} Lantern Complexes Including a Ferromagnetically Coupled 1D Coordination Polymer.

PubMed

Guillet, Jesse L; Bhowmick, Indrani; Shores, Matthew P; Daley, Christopher J A; Gembicky, Milan; Golen, James A; Rheingold, Arnold L; Doerrer, Linda H

2016-08-15

A series of heterobimetallic lantern complexes with the central unit {PtM(SAc)4(NCS)} have been prepared and thoroughly characterized. The {Na(15C5)}[PtM(SAc)4(NCS)] series, 1 (Co), 2 (Ni), 3 (Zn), are discrete compounds in the solid state, whereas the {Na(12C4)2)}[PtM(SAc)4(NCS)] series, 4 (Co), 5 (Ni), 6 (Zn), and 7 (Mn), are ion-separated species. Compound 7 is the first {PtMn} lantern of any bridging ligand (carboxylate, amide, etc.). Monomeric 1-7 have M(2+), necessitating counter cations that have been prepared as {(15C5)Na}(+) and {(12C4)2Na}(+) variants, none of which form extended structures. In contrast, neutral [PtCr(tba)4(NCS)]∞ 8 forms a coordination polymer of {PtCr}(+) units linked by (NCS)(-) in a zigzag chain. All eight compounds have been thoroughly characterized and analyzed in comparison to a previously reported family of compounds. Crystal structures are presented for compounds 1-6 and 8, and solution magnetic susceptibility measurements are presented for compounds 1, 2, 4, 5, and 7. Further structural analysis of dimerized {PtM} units reinforces the empirical observation that greater charge density along the Pt-M vector leads to more Pt···Pt interactions in the solid state. Four structural classes, one new, of {MPt}···{PtM} units are presented. Solid state magnetic characterization of 8 reveals a ferromagnetic interaction in the {PtCr(NCS)} chain between the Cr centers of J/kB = 1.7(4) K.

Secondary foundation species as drivers of trophic and functional diversity: evidence from a tree-epiphyte system.

PubMed

Angelini, Christine; Silliman, Brian R

2014-01-01

Facilitation cascades arise where primary foundation species facilitate secondary (dependent) foundation species, and collectively, they increase habitat complexity and quality to enhance biodiversity. Whether such phenomena occur in nonmarine systems and if secondary foundation species enhance food web structure (e.g., support novel feeding guilds) and ecosystem function (e.g., provide nursery for juveniles) remain unclear. Here we report on field experiments designed to test whether trees improve epiphyte survival and epiphytes secondarily increase the number and diversity of adult and juvenile invertebrates in a potential live oak-Tillandsia usneoides (Spanish moss) facilitation cascade. Our results reveal that trees reduce physical stress to facilitate Tillandsia, which, in turn, reduces desiccation and predation stress to facilitate invertebrates. In experimental removals, invertebrate total density, juvenile density, species richness and H' diversity were 16, 60, 1.7, and 1.5 times higher, and feeding guild richness and H' were 5 and 11 times greater in Tillandsia-colonized relative to Tillandsia-removal limb plots. Tillandsia enhanced communities similarly in a survey across the southeastern United States. These findings reveal that a facilitation cascade organizes this widespread terrestrial assemblage and expand the role of secondary foundation species as drivers of trophic structure and ecosystem function. We conceptualize the relationship between foundation species' structural attributes and associated species abundance and composition in a Foundation Species-Biodiversity (FSB) model. Importantly, the FSB predicts that, where secondary foundation species form expansive and functionally distinct structures that increase habitat availability and complexity within primary foundation species, they generate and maintain hot spots of biodiversity and trophic interactions.

The Axl kinase domain in complex with a macrocyclic inhibitor offers first structural insights into an active TAM receptor kinase.

PubMed

Gajiwala, Ketan S; Grodsky, Neil; Bolaños, Ben; Feng, Junli; Ferre, RoseAnn; Timofeevski, Sergei; Xu, Meirong; Murray, Brion W; Johnson, Ted W; Stewart, Al

2017-09-22

The receptor tyrosine kinase family consisting of Tyro3, Axl, and Mer (TAM) is one of the most recently identified receptor tyrosine kinase families. TAM receptors are up-regulated postnatally and maintained at high levels in adults. They all play an important role in immunity, but Axl has also been implicated in cancer and therefore is a target in the discovery and development of novel therapeutics. However, of the three members of the TAM family, the Axl kinase domain is the only one that has so far eluded structure determination. To this end, using differential scanning fluorimetry and hydrogen-deuterium exchange mass spectrometry, we show here that a lower stability and greater dynamic nature of the Axl kinase domain may account for its poor crystallizability. We present the first structural characterization of the Axl kinase domain in complex with a small-molecule macrocyclic inhibitor. The Axl crystal structure revealed two distinct conformational states of the enzyme, providing a first glimpse of what an active TAM receptor kinase may look like and suggesting a potential role for the juxtamembrane region in enzyme activity. We noted that the ATP/inhibitor-binding sites of the TAM members closely resemble each other, posing a challenge for the design of a selective inhibitor. We propose that the differences in the conformational dynamics among the TAM family members could potentially be exploited to achieve inhibitor selectivity for targeted receptors. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Age Differences in the Complexity of Emotion Perception.

PubMed

Kim, Seungyoun; Geren, Jennifer L; Knight, Bob G

2015-01-01

The current study examined age differences in the number of emotion components used in the judgment of emotion from facial expressions. Fifty-eight younger and 58 older adults were compared on the complexity of perception of emotion from standardized facial expressions that were either clear or ambiguous exemplars of emotion. Using an intra-individual factor analytic approach, results showed that older adults used more emotion components in perceiving emotion in faces than younger adults. Both age groups reported greater emotional complexity for the clear and prototypical emotional stimuli. Age differences in emotional complexity were more pronounced for the ambiguous expressions compared with the clear expressions. These findings demonstrate that older adults showed increased elaboration of emotion, particularly when emotion cues were subtle and provide support for greater emotion differentiation in older adulthood.

Measurements of car-body lateral vibration induced by high-speed trains negotiating complex terrain sections under strong wind conditions

NASA Astrophysics Data System (ADS)

Liu, Dongrun; Lu, Zhaijun; Zhong, Mu; Cao, Tianpei; Chen, Dong; Xiong, Yupu

2018-02-01

Assessment of the vibration of high-speed trains negotiating complex sections of terrain under strong wind conditions is very important for research into the operation safety and comfort of passengers on high-speed trains. To assess the vibration of high-speed trains negotiating complex sections of terrain under strong wind conditions, we performed a field measurement when the train passes through typical sections of complex terrain along the Lanzhou-Xinjiang high-speed railway in China. We selected the lateral vibration conditions, including the roll angle and lateral displacement of car-body gravity centre through two typical representative sections (embankment-tunnel-embankment and embankment-rectangular transition-cutting) for analysis. The results show that the severe car-swaying phenomenon occurs when the high-speed train moves through the test section, and the car-body lateral vibration characteristic is related significantly to the state of the terrain and topography along the railway. The main causes for this car-swaying phenomenon may be the transitions between different windproof structures, and the greater the scale of the transition region between different windproof structures or landform changes, the more obvious the car-swaying phenomenon becomes. The lateral vibration of the car-body is relatively steady when the train is running through terrain with minor changes in topography, such as the windbreak installed on the bridge and embankment, but the tail car sways more violently than the head car. When the vehicle runs from the windbreak installed on the embankment into the tunnel (or in the opposite direction), the tail car sways more intensely than the head car, and the head car runs relatively stable in the tunnel.

Template-based structure modeling of protein-protein interactions

PubMed Central

Szilagyi, Andras; Zhang, Yang

2014-01-01

The structure of protein-protein complexes can be constructed by using the known structure of other protein complexes as a template. The complex structure templates are generally detected either by homology-based sequence alignments or, given the structure of monomer components, by structure-based comparisons. Critical improvements have been made in recent years by utilizing interface recognition and by recombining monomer and complex template libraries. Encouraging progress has also been witnessed in genome-wide applications of template-based modeling, with modeling accuracy comparable to high-throughput experimental data. Nevertheless, bottlenecks exist due to the incompleteness of the proteinprotein complex structure library and the lack of methods for distant homologous template identification and full-length complex structure refinement. PMID:24721449

Characterization and structural study of the complex of Al(III) with 2,4-dihydroxy-benzophenone. Ionic strength and solvent effects.

PubMed

Castro, G T; Blanco, S E; Arce, S L; Ferretti, F H

2003-10-01

The complexation reaction between AlCl(3) and 2,4-dihydroxy-benzophenone with varying permittivity and ionic strength of the reaction medium was investigated by theoretical and experimental procedures, namely, density functional (DFT) and UV-vis spectroscopic methods, respectively. The stoichiometric composition of the complex formed, which was determined by means of the molar ratio method, is 1:1. The molar absorptivity and stability constant of the complex were determined using a method designed by the authors. It was observed that the stoichiometric composition of the complex does not change with the used solvents and that the stability constant in methanol is higher than ethanol. Kinetic experiments in solutions with different ionic strength were also performed. The results obtained permit to conclude that the complex is formed through of a mechanism whose rate-determining step is a reaction between two ions with opposite unitary charges. In the theoretical study performed at the B3LYP/6-31G(d) level of theory using Tomasi's model, it was proposed that the formation of the complex involves one simple covalent bond between the aluminum atom and the oxygen atom of o-hydroxyl group of the ligand and a stronger coulombic attraction (or a second covalent bond) between the central atom and the carbonyl oxygen atom of 2,4-dihydroxy-benzophenone. Using the calculated magnitudes, it was predicted that the complex formed has higher thermodynamic stability in methanol than ethanol. It was also concluded that the planarity of the chelate ring favors a greater planarity of 4-hydroxy-benzoyl group of the complex with respect to the ligand, which agrees with the observed batochromic shifts. The formulated theoretical conclusions satisfactorily match the experimental determinations performed.

Speaking under pressure: low linguistic complexity is linked to high physiological and emotional stress reactivity.

PubMed

Saslow, Laura R; McCoy, Shannon; van der Löwe, Ilmo; Cosley, Brandon; Vartan, Arbi; Oveis, Christopher; Keltner, Dacher; Moskowitz, Judith T; Epel, Elissa S

2014-03-01

What can a speech reveal about someone's state? We tested the idea that greater stress reactivity would relate to lower linguistic cognitive complexity while speaking. In Study 1, we tested whether heart rate and emotional stress reactivity to a stressful discussion would relate to lower linguistic complexity. In Studies 2 and 3, we tested whether a greater cortisol response to a standardized stressful task including a speech (Trier Social Stress Test) would be linked to speaking with less linguistic complexity during the task. We found evidence that measures of stress responsivity (emotional and physiological) and chronic stress are tied to variability in the cognitive complexity of speech. Taken together, these results provide evidence that our individual experiences of stress or "stress signatures"-how our body and mind react to stress both in the moment and over the longer term-are linked to how complex our speech under stress. Copyright © 2013 Society for Psychophysiological Research.

Clobazam and its active metabolite N-desmethylclobazam display significantly greater affinities for α₂- versus α₁-GABA(A)-receptor complexes.

PubMed

Jensen, Henrik Sindal; Nichol, Kathryn; Lee, Deborah; Ebert, Bjarke

2014-01-01

Clobazam (CLB), a 1,5-benzodiazepine (BZD), was FDA-approved in October 2011 for the adjunctive treatment of seizures associated with Lennox-Gastaut syndrome (LGS) in patients 2 years and older. BZDs exert various CNS effects through allosteric modulation of GABAA receptors. The structurally distinct, 1,4-BZD clonazepam (CLN) is also approved to treat LGS. The precise mechanisms of action and clinical efficacy of both are unknown. Data show that the GABAA α₁-subunit-selective compound zolpidem [ZOL] exhibits hypnotic/sedative effects. Conversely, data from knock-in mice carrying BZD binding site mutations suggest that the α₂ subunit mediates anticonvulsant effects, without sedative actions. Hence, the specific pattern of interactions across the GABAA receptor complexes of BZDs might be reflected in their clinical efficacies and adverse effect profiles. In this study, GABAA-receptor binding affinities of CLB, N-desmethylclobazam (N-CLB, the major metabolite of CLB), CLN, and ZOL were characterized with native receptors from rat-brain homogenates and on cloned receptors from HEK293 cells transfected with combinations of α (α₁, α₂, α₃, or α₅), β₂, and γ₂ subtypes. Our results demonstrate that CLB and N-CLB have significantly greater binding affinities for α₂- vs. α₁-receptor complexes, a difference not observed for CLN, for which no distinction between α₂ and α₁ receptors was observed. Our experiments with ZOL confirmed the high preference for α₁ receptors. These results provide potential clues to a new understanding of the pharmacologic modes of action of CLB and N-CLB.

Clobazam and Its Active Metabolite N-desmethylclobazam Display Significantly Greater Affinities for α2- versus α1-GABAA–Receptor Complexes

PubMed Central

Jensen, Henrik Sindal; Nichol, Kathryn; Lee, Deborah; Ebert, Bjarke

2014-01-01

Clobazam (CLB), a 1,5-benzodiazepine (BZD), was FDA-approved in October 2011 for the adjunctive treatment of seizures associated with Lennox-Gastaut syndrome (LGS) in patients 2 years and older. BZDs exert various CNS effects through allosteric modulation of GABAA receptors. The structurally distinct, 1,4-BZD clonazepam (CLN) is also approved to treat LGS. The precise mechanisms of action and clinical efficacy of both are unknown. Data show that the GABAA α1-subunit–selective compound zolpidem [ZOL] exhibits hypnotic/sedative effects. Conversely, data from knock-in mice carrying BZD binding site mutations suggest that the α2 subunit mediates anticonvulsant effects, without sedative actions. Hence, the specific pattern of interactions across the GABAA receptor complexes of BZDs might be reflected in their clinical efficacies and adverse effect profiles. In this study, GABAA-receptor binding affinities of CLB, N-desmethylclobazam (N-CLB, the major metabolite of CLB), CLN, and ZOL were characterized with native receptors from rat-brain homogenates and on cloned receptors from HEK293 cells transfected with combinations of α (α1, α2, α3, or α5), β2, and γ2 subtypes. Our results demonstrate that CLB and N-CLB have significantly greater binding affinities for α2- vs. α1-receptor complexes, a difference not observed for CLN, for which no distinction between α2 and α1 receptors was observed. Our experiments with ZOL confirmed the high preference for α1 receptors. These results provide potential clues to a new understanding of the pharmacologic modes of action of CLB and N-CLB. PMID:24533090

Inter-subject synchronization of brain responses during natural music listening.

PubMed

Abrams, Daniel A; Ryali, Srikanth; Chen, Tianwen; Chordia, Parag; Khouzam, Amirah; Levitin, Daniel J; Menon, Vinod

2013-05-01

Music is a cultural universal and a rich part of the human experience. However, little is known about common brain systems that support the processing and integration of extended, naturalistic 'real-world' music stimuli. We examined this question by presenting extended excerpts of symphonic music, and two pseudomusical stimuli in which the temporal and spectral structure of the Natural Music condition were disrupted, to non-musician participants undergoing functional brain imaging and analysing synchronized spatiotemporal activity patterns between listeners. We found that music synchronizes brain responses across listeners in bilateral auditory midbrain and thalamus, primary auditory and auditory association cortex, right-lateralized structures in frontal and parietal cortex, and motor planning regions of the brain. These effects were greater for natural music compared to the pseudo-musical control conditions. Remarkably, inter-subject synchronization in the inferior colliculus and medial geniculate nucleus was also greater for the natural music condition, indicating that synchronization at these early stages of auditory processing is not simply driven by spectro-temporal features of the stimulus. Increased synchronization during music listening was also evident in a right-hemisphere fronto-parietal attention network and bilateral cortical regions involved in motor planning. While these brain structures have previously been implicated in various aspects of musical processing, our results are the first to show that these regions track structural elements of a musical stimulus over extended time periods lasting minutes. Our results show that a hierarchical distributed network is synchronized between individuals during the processing of extended musical sequences, and provide new insight into the temporal integration of complex and biologically salient auditory sequences. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

A search for embedded young stellar objects in and near the IC 1396 complex

NASA Technical Reports Server (NTRS)

Schwartz, Richard D.; Wilking, Bruce A.; Giulbudagian, Armen L.

1991-01-01

The IRAS data base is used to locate young stellar object candidates in and near the IC 1396 complex located in the Cepheus OB2 association. Co-added survey data are used to identify all sources with a flux density Snu(100) greater than 10 Jy and with Snu(100) greater than Snu(60). The 15 sources located at the positions of globules and dark clouds are further analyzed using the inscan slices to assess the source profiles.

Nanoscale Morphology of Type I Collagen is Altered in the Brtl Mouse Model of Osteogenesis Imperfecta

PubMed Central

Wallace, Joseph M.; Orr, Bradford G.; Marini, Joan C.; Banaszak Holl, Mark M.

2010-01-01

Bone has a complex hierarchical structure that has evolved to serve structural and metabolic roles in the body. Due to the complexity of bone structure and the number of diseases which affect the ultrastructural constituents of bone, it is important to develop quantitative methods to assess bone nanoscale properties. Autosomal dominant Osteogenesis Imperfecta results predominantly from glycine substitutions (80%) and splice site mutations (20%) in the genes encoding the α1 or α2 chains of Type I collagen. Genotype-phenotype correlations using over 830 collagen mutations have revealed that lethal mutations are located in regions crucial for collagen-ligand binding in the matrix. However, few of these correlations have been extended to collagen structure in bone. Here, an atomic force microscopy-based approach was used to image and quantitatively analyze the D-periodic spacing of Type I collagen fibrils in femora from heterozygous (Brtl/+) mice (α1(I)G349C), compared to wild type (WT) littermates. This disease system has a well-defined change in the col1α1 allele, leading to a well characterized alteration in collagen protein structure, which are directly related to altered Type I collagen nanoscale morphology, as measured by the D-periodic spacing. In Brtl/+ bone, the D-periodic spacing shows significantly greater variability on average and along the length of the bone compared to WT, although the average spacing was unchanged. Brtl/+ bone also had a significant difference in the population distribution of collagen D-period spacings. These changes may be due to the mutant collagen structure, or to the heterogeneity of collagen monomers in the Brtl/+ matrix. These observations at the nanoscale level provide insight into the structural basis for changes present in bone composition, geometry and mechanical integrity in Brtl/+ bones. Further studies are necessary to link these morphological observations to nanoscale mechanical integrity. PMID:20696252

A Matrix-Free Algorithm for Multidisciplinary Design Optimization

NASA Astrophysics Data System (ADS)

Lambe, Andrew Borean

Multidisciplinary design optimization (MDO) is an approach to engineering design that exploits the coupling between components or knowledge disciplines in a complex system to improve the final product. In aircraft design, MDO methods can be used to simultaneously design the outer shape of the aircraft and the internal structure, taking into account the complex interaction between the aerodynamic forces and the structural flexibility. Efficient strategies are needed to solve such design optimization problems and guarantee convergence to an optimal design. This work begins with a comprehensive review of MDO problem formulations and solution algorithms. First, a fundamental MDO problem formulation is defined from which other formulations may be obtained through simple transformations. Using these fundamental problem formulations, decomposition methods from the literature are reviewed and classified. All MDO methods are presented in a unified mathematical notation to facilitate greater understanding. In addition, a novel set of diagrams, called extended design structure matrices, are used to simultaneously visualize both data communication and process flow between the many software components of each method. For aerostructural design optimization, modern decomposition-based MDO methods cannot efficiently handle the tight coupling between the aerodynamic and structural states. This fact motivates the exploration of methods that can reduce the computational cost. A particular structure in the direct and adjoint methods for gradient computation motivates the idea of a matrix-free optimization method. A simple matrix-free optimizer is developed based on the augmented Lagrangian algorithm. This new matrix-free optimizer is tested on two structural optimization problems and one aerostructural optimization problem. The results indicate that the matrix-free optimizer is able to efficiently solve structural and multidisciplinary design problems with thousands of variables and constraints. On the aerostructural test problem formulated with thousands of constraints, the matrix-free optimizer is estimated to reduce the total computational time by up to 90% compared to conventional optimizers.

A Matrix-Free Algorithm for Multidisciplinary Design Optimization

NASA Astrophysics Data System (ADS)

Lambe, Andrew Borean

Multidisciplinary design optimization (MDO) is an approach to engineering design that exploits the coupling between components or knowledge disciplines in a complex system to improve the final product. In aircraft design, MDO methods can be used to simultaneously design the outer shape of the aircraft and the internal structure, taking into account the complex interaction between the aerodynamic forces and the structural flexibility. Efficient strategies are needed to solve such design optimization problems and guarantee convergence to an optimal design. This work begins with a comprehensive review of MDO problem formulations and solution algorithms. First, a fundamental MDO problem formulation is defined from which other formulations may be obtained through simple transformations. Using these fundamental problem formulations, decomposition methods from the literature are reviewed and classified. All MDO methods are presented in a unified mathematical notation to facilitate greater understanding. In addition, a novel set of diagrams, called extended design structure matrices, are used to simultaneously visualize both data communication and process flow between the many software components of each method. For aerostructural design optimization, modern decomposition-based MDO methods cannot efficiently handle the tight coupling between the aerodynamic and structural states. This fact motivates the exploration of methods that can reduce the computational cost. A particular structure in the direct and adjoint methods for gradient computation. motivates the idea of a matrix-free optimization method. A simple matrix-free optimizer is developed based on the augmented Lagrangian algorithm. This new matrix-free optimizer is tested on two structural optimization problems and one aerostructural optimization problem. The results indicate that the matrix-free optimizer is able to efficiently solve structural and multidisciplinary design problems with thousands of variables and constraints. On the aerostructural test problem formulated with thousands of constraints, the matrix-free optimizer is estimated to reduce the total computational time by up to 90% compared to conventional optimizers.

Warming alters community size structure and ecosystem functioning

PubMed Central

Dossena, Matteo; Yvon-Durocher, Gabriel; Grey, Jonathan; Montoya, José M.; Perkins, Daniel M.; Trimmer, Mark; Woodward, Guy

2012-01-01

Global warming can affect all levels of biological complexity, though we currently understand least about its potential impact on communities and ecosystems. At the ecosystem level, warming has the capacity to alter the structure of communities and the rates of key ecosystem processes they mediate. Here we assessed the effects of a 4°C rise in temperature on the size structure and taxonomic composition of benthic communities in aquatic mesocosms, and the rates of detrital decomposition they mediated. Warming had no effect on biodiversity, but altered community size structure in two ways. In spring, warmer systems exhibited steeper size spectra driven by declines in total community biomass and the proportion of large organisms. By contrast, in autumn, warmer systems had shallower size spectra driven by elevated total community biomass and a greater proportion of large organisms. Community-level shifts were mirrored by changes in decomposition rates. Temperature-corrected microbial and macrofaunal decomposition rates reflected the shifts in community structure and were strongly correlated with biomass across mesocosms. Our study demonstrates that the 4°C rise in temperature expected by the end of the century has the potential to alter the structure and functioning of aquatic ecosystems profoundly, as well as the intimate linkages between these levels of ecological organization. PMID:22496185

The dynamic relationship between cerebellar Purkinje cell simple spikes and the spikelet number of complex spikes

PubMed Central

Burroughs, Amelia; Wise, Andrew K.; Xiao, Jianqiang; Houghton, Conor; Tang, Tianyu; Suh, Colleen Y.; Lang, Eric J.

2016-01-01

Key points Purkinje cells are the sole output of the cerebellar cortex and fire two distinct types of action potential: simple spikes and complex spikes.Previous studies have mainly considered complex spikes as unitary events, even though the waveform is composed of varying numbers of spikelets.The extent to which differences in spikelet number affect simple spike activity (and vice versa) remains unclear.We found that complex spikes with greater numbers of spikelets are preceded by higher simple spike firing rates but, following the complex spike, simple spikes are reduced in a manner that is graded with spikelet number.This dynamic interaction has important implications for cerebellar information processing, and suggests that complex spike spikelet number may maintain Purkinje cells within their operational range. Abstract Purkinje cells are central to cerebellar function because they form the sole output of the cerebellar cortex. They exhibit two distinct types of action potential: simple spikes and complex spikes. It is widely accepted that interaction between these two types of impulse is central to cerebellar cortical information processing. Previous investigations of the interactions between simple spikes and complex spikes have mainly considered complex spikes as unitary events. However, complex spikes are composed of an initial large spike followed by a number of secondary components, termed spikelets. The number of spikelets within individual complex spikes is highly variable and the extent to which differences in complex spike spikelet number affects simple spike activity (and vice versa) remains poorly understood. In anaesthetized adult rats, we have found that Purkinje cells recorded from the posterior lobe vermis and hemisphere have high simple spike firing frequencies that precede complex spikes with greater numbers of spikelets. This finding was also evident in a small sample of Purkinje cells recorded from the posterior lobe hemisphere in awake cats. In addition, complex spikes with a greater number of spikelets were associated with a subsequent reduction in simple spike firing rate. We therefore suggest that one important function of spikelets is the modulation of Purkinje cell simple spike firing frequency, which has implications for controlling cerebellar cortical output and motor learning. PMID:27265808

Geobase Information System Impacts on Space Image Formats

NASA Technical Reports Server (NTRS)

Simonett, D. S. (Editor); Smith, T. R. (Editor); Tobler, W. (Editor); Marks, D. G. (Editor); Frew, J. E. (Editor); Dozier, J. C. (Editor)

1978-01-01

As Geobase Information Systems increase in number, size and complexity, the format compatability of satellite remote sensing data becomes increasingly more important. Because of the vast and continually increasing quantity of data available from remote sensing systems the utility of these data is increasingly dependent on the degree to which their formats facilitate, or hinder, their incorporation into Geobase Information Systems. To merge satellite data into a geobase system requires that they both have a compatible geographic referencing system. Greater acceptance of satellite data by the user community will be facilitated if the data are in a form which most readily corresponds to existing geobase data structures. The conference addressed a number of specific topics and made recommendations.

Tannins, peptic ulcers and related mechanisms.

PubMed

de Jesus, Neyres Zinia Taveira; de Souza Falcão, Heloina; Gomes, Isis Fernandes; de Almeida Leite, Thiago Jose; de Morais Lima, Gedson Rodrigues; Barbosa-Filho, Jose Maria; Tavares, Josean Fechine; da Silva, Marcelo Sobral; de Athayde-Filho, Petrônio Filgueiras; Batista, Leonia Maria

2012-01-01

This review of the current literature aims to study correlations between the chemical structure and gastric anti-ulcer activity of tannins. Tannins are used in medicine primarily because of their astringent properties. These properties are due to the fact that tannins react with the tissue proteins with which they come into contact. In gastric ulcers, this tannin-protein complex layer protects the stomach by promoting greater resistance to chemical and mechanical injury or irritation. Moreover, in several experimental models of gastric ulcer, tannins have been shown to present antioxidant activity, promote tissue repair, exhibit anti Helicobacter pylori effects, and they are involved in gastrointestinal tract anti-inflammatory processes. The presence of tannins explains the anti-ulcer effects of many natural products.

Comprehensive Environmental Assessment: A Meta-Assessment Approach

PubMed Central

2012-01-01

With growing calls for changes in the field of risk assessment, improved systematic approaches for addressing environmental issues with greater transparency and stakeholder engagement are needed to ensure sustainable trade-offs. Here we describe the comprehensive environmental assessment (CEA) approach as a holistic way to manage complex information and to structure input from diverse stakeholder perspectives to support environmental decision-making for the near- and long-term. We further note how CEA builds upon and incorporates other available tools and approaches, describe its current application at the U.S. Environmental Protection Agency, and point out how it could be extended in evaluating a major issue such as the sustainability of biofuels. PMID:22889372

Physical and chemical evolution of reduced organic matter in the ISM

NASA Technical Reports Server (NTRS)

Jenniskens, Peter; Blake, David F.

1995-01-01

Icy mantles on interstellar grains have been a topic of study in airborne astronomy. Recent laboratory analog studies of the yield of organic residue from UV photolyzed ices have shown that this mechanism can be the most significant source of complex reduced organic matter in the interstellar medium. However, the total yield is a function of the occurrence of heating events that evaporate the ice, i.e. T is greater than 130 K, and the mechanism for such events is debated. Recently, we proposed that the recombination of radicals in the ice does not need high temperature excursions and, instead, occurs during a structural transformation of water ice at temperatures in the range 38 - 68 K.

ASCA X-ray observations of pre-main-sequence stars

NASA Technical Reports Server (NTRS)

Skinner, S. L.; Walter, F. M.; Yamauchi, S.

1996-01-01

The results of recent Advanced Satellite for Cosmology and Astrophysics (ASCA) X-ray observations of two pre-main sequence stars are presented: the weak emission line T Tauri star HD 142361, and the Herbig Ae star HD 104237. The solid state imaging spectrometer spectra for HD 142361 shows a clear emission line from H-like Mg 7, and spectral fits reveal a multiple temperature plasma with a hot component of at least 16 MK. The spectra of HD 104237 show a complex temperature structure with the hottest plasma at temperatures of greater than 30 MK. It is concluded that mechanisms that predict only soft X-ray emission can be dismissed for Herbig Ae stars.

Cascading failures in interdependent networks with finite functional components

NASA Astrophysics Data System (ADS)

Di Muro, M. A.; Buldyrev, S. V.; Stanley, H. E.; Braunstein, L. A.

2016-10-01

We present a cascading failure model of two interdependent networks in which functional nodes belong to components of size greater than or equal to s . We find theoretically and via simulation that in complex networks with random dependency links the transition is first order for s ≥3 and continuous for s =2 . We also study interdependent lattices with a distance constraint r in the dependency links and find that increasing r moves the system from a regime without a phase transition to one with a second-order transition. As r continues to increase, the system collapses in a first-order transition. Each regime is associated with a different structure of domain formation of functional nodes.

Metasurface Broadband Solar Absorber

DOE PAGES

Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; ...

2016-02-01

Here, we demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Moreover, our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributionsmore » to elucidate how the absorption occurs within the metasurface structure.« less

Metasurface Broadband Solar Absorber

PubMed Central

Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

2016-01-01

We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

Using ecological zones to increase the detail of Landsat classifications

NASA Technical Reports Server (NTRS)

Fox, L., III; Mayer, K. E.

1981-01-01

Changes in classification detail of forest species descriptions were made for Landsat data on 2.2 million acres in northwestern California. Because basic forest canopy structures may exhibit very similar E-M energy reflectance patterns in different environmental regions, classification labels based on Landsat spectral signatures alone become very generalized when mapping large heterogeneous ecological regions. By adding a seven ecological zone stratification, a 167% improvement in classification detail was made over the results achieved without it. The seven zone stratification is a less costly alternative to the inclusion of complex collateral information, such as terrain data and soil type, into the Landsat data base when making inventories of areas greater than 500,000 acres.

A homogeneous 2D deformation of geological interest: Rotation shear

NASA Astrophysics Data System (ADS)

Bastida, Fernando; Bobillo-Ares, Nilo C.; Aller, Jesús; Lisle, Richard J.

2018-07-01

We define a simple two-dimensional deformation called "rotation shear". It has one line of no finite longitudinal strain with invariant direction and another one that rotates with the deformation. An analysis of this deformation is carried out. Rotation shear superficially resembles simple shear but the analysis reveals that the two deformations have very different properties. In general, lines deformed by simple shear show a more complex deformation history and undergo greater longitudinal strain, i.e. are more extended, than lines deformed by rotation shear. Rotation shear is used to explain the development of geological structures such as kink bands, ideal similar folds, crenulation and crenulation cleavage and shear zones.

Front Range Infrastructure Resources Project--Biological Resources

USGS Publications Warehouse

,

1998-01-01

Riparian (streamside) vegetation communities are of interest in the context of the Front Range Infrastructure Resources Project (FRIRP) because they are often a focal point for conflicting societal demands. The cottonwoods and willows comprising these communities are structurally complex compared to the surrounding landscape and support diverse assemblages of mammals, birds, reptiles, and amphibians. However, riparian areas are also primary sites for water development, agriculture, grazing, sand and gravel mining, and recreation, each of which may limit other uses. Direct and indirect impacts of these activities have led to exploration of new opportunities and techniques for restoring disturbed riparian habitats and to greater concern for some of the scarce species that inhabit them.

Viscoelastic and fractal characteristics of a supramolecular hydrogel hybridized with clay nanoparticles.

PubMed

Song, Fei; Zhang, Li-Ming; Shi, Jun-Feng; Li, Nan-Nan

2010-12-01

The supramolecular hydrogels derived from low-molecular-mass gelators represent a unique class of soft matters and have important potential applications in biomedical fields, separation technology and cosmetic science. However, they suffer usually from weak mechanical and viscoelastic properties. In this work, we carry out the in situ hybridization of clay nanoparticles (Laponite RD) into the supramolecular hydrogel formed from a low-molecular-mass hydrogelator, 2,6-di[N-(carboxyethyl carbonyl)amino]pyridine (DAP), and investigate the viscoelastic and structural characteristics of resultant hybrid hydrogel. It was found that a small concentration of Laponite RD could lead to a significant increase in the storage modulus, loss modulus or complex viscosity. Compared with neat DAP hydrogel, the hybrid hydrogel has a greater hydrogel strength and a lower relaxation exponent. In particular, the enhancement of the clay nanoparticles to the viscoelastic properties of the DAP hydrogel is more effective in the case of higher DAP concentration. By relating its macroscopic elastic properties to a scaling fractal model, such a hybrid hydrogel was confirmed to be in the strong-link regime and to have a more complex network structure with a higher fractal dimension when compared with neat DAP hydrogel. Copyright © 2010 Elsevier B.V. All rights reserved.

Three-dimensional analysis of the early development of the dentition

PubMed Central

Peterkova, R; Hovorakova, M; Peterka, M; Lesot, H

2014-01-01

Tooth development has attracted the attention of researchers since the 19th century. It became obvious even then that morphogenesis could not fully be appreciated from two-dimensional histological sections. Therefore, methods of three-dimensional (3D) reconstructions were employed to visualize the surface morphology of developing structures and to help appreciate the complexity of early tooth morphogenesis. The present review surveys the data provided by computer-aided 3D analyses to update classical knowledge of early odontogenesis in the laboratory mouse and in humans. 3D reconstructions have demonstrated that odontogenesis in the early stages is a complex process which also includes the development of rudimentary odontogenic structures with different fates. Their developmental, evolutionary, and pathological aspects are discussed. The combination of in situ hybridization and 3D reconstruction have demonstrated the temporo-spatial dynamics of the signalling centres that reflect transient existence of rudimentary tooth primordia at loci where teeth were present in ancestors. The rudiments can rescue their suppressed development and revitalize, and then their subsequent autonomous development can give rise to oral pathologies. This shows that tooth-forming potential in mammals can be greater than that observed from their functional dentitions. From this perspective, the mouse rudimentary tooth primordia represent a natural model to test possibilities of tooth regeneration. PMID:24495023

Contemporary Tools and Techniques for Substrate Ablation of Ventricular Tachycardia in Structural Heart Disease.

PubMed

Hutchinson, Mathew D; Garza, Hyon-He K

2018-02-24

As we have witnessed in other arenas of catheter-based therapeutics, ventricular tachycardia (VT) ablation has become increasingly anatomical in its execution. Multi-modality imaging provides anatomical detail in substrate characterization, which is often complex in nonischemic cardiomyopathy patients. Patients with intramural, intraseptal, and epicardial substrates provide challenges in delivering effective ablation to the critical arrhythmia substrate due to the depth of origin or the presence of adjacent critical structures. Novel ablation techniques such as simultaneous unipolar or bipolar ablation can be useful to achieve greater lesion depth, though at the expense of increasing collateral damage. Disruptive technologies like stereotactic radioablation may provide a tailored approach to these complex patients while minimizing procedural risk. Substrate ablation is a cornerstone of the contemporary VT ablation procedure, and recent data suggest that it is as effective and more efficient that conventional activation guided ablation. A number of specific targets and techniques for substrate ablation have been described, and all have shown a fairly high success in achieving their acute procedural endpoint. Substrate ablation also provides a novel and reproducible procedural endpoint, which may add predictive value for VT recurrence beyond conventional programmed stimulation. Extrapolation of outcome data to nonischemic phenotypes requires caution given both the variability in substrate nonischemic distribution and the underrepresentation of these patients in previous trials.

CSBB-ConeExclusion, adapting structure based solution virtual screening to libraries on solid support.

PubMed

Shave, Steven; Auer, Manfred

2013-12-23

Combinatorial chemical libraries produced on solid support offer fast and cost-effective access to a large number of unique compounds. If such libraries are screened directly on-bead, the speed at which chemical space can be explored by chemists is much greater than that addressable using solution based synthesis and screening methods. Solution based screening has a large supporting body of software such as structure-based virtual screening tools which enable the prediction of protein-ligand complexes. Use of these techniques to predict the protein bound complexes of compounds synthesized on solid support neglects to take into account the conjugation site on the small molecule ligand. This may invalidate predicted binding modes, the linker may be clashing with protein atoms. We present CSBB-ConeExclusion, a methodology and computer program which provides a measure of the applicability of solution dockings to solid support. Output is given in the form of statistics for each docking pose, a unique 2D visualization method which can be used to determine applicability at a glance, and automatically generated PyMol scripts allowing visualization of protein atom incursion into a defined exclusion volume. CSBB-ConeExclusion is then exemplarically used to determine the optimum attachment point for a purine library targeting cyclin-dependent kinase 2 CDK2.

Characterization of Non-Innocent Metal Complexes Using Solid-State NMR Spectroscopy: o-Dioxolene Vanadium Complexes

PubMed Central

Chatterjee, Pabitra B.; Goncharov-Zapata, Olga; Quinn, Laurence L.; Hou, Guangjin; Hamaed, Hiyam; Schurko, Robert W.; Polenova, Tatyana; Crans, Debbie C.

2012-01-01

51V solid-state NMR (SSNMR) studies of a series of non-innocent vanadium(V) catechol complexes have been conducted to evaluate the possibility that 51V NMR observables, quadrupolar and chemical shift anisotropies, and electronic structures of such compounds can be used to characterize these compounds. The vanadium(V) catechol complexes described in these studies have relatively small quadrupolar coupling constants, which cover a surprisingly small range from 3.4 to 4.2 MHz. On the other hand, isotropic 51V NMR chemical shifts cover a wide range from −200 ppm to 400 ppm in solution and from −219 to 530 ppm in the solid state. A linear correlation of 51V NMR isotropic solution and solid-state chemical shifts of complexes containing non-innocent ligands is observed. These experimental results provide the information needed for the application of 51V SSNMR spectroscopy in characterizing the electronic properties of a wide variety of vanadium-containing systems, and in particular those containing non-innocent ligands and that have chemical shifts outside the populated range of −300 ppm to −700 ppm. The studies presented in this report demonstrate that the small quadrupolar couplings covering a narrow range of values reflect the symmetric electronic charge distribution, which is also similar across these complexes. These quadrupolar interaction parameters alone are not sufficient to capture the rich electronic structure of these complexes. In contrast, the chemical shift anisotropy tensor elements accessible from 51V SSNMR experiments are a highly sensitive probe of subtle differences in electronic distribution and orbital occupancy in these compounds. Quantum chemical (DFT) calculations of NMR parameters for [VO(hshed)(Cat)] yield 51V CSA tensor in reasonable agreement with the experimental results, but surprisingly, the calculated quadrupolar coupling constant is significantly greater than the experimental value. The studies demonstrate that substitution of the catechol ligand with electron donating groups results in an increase in the HOMO-LUMO gap and can be directly followed by an upfield shift for the vanadium catechol complex. In contrast, substitution of the catechol ligand with electron withdrawing groups results in a decrease in the HOMO-LUMO gap and can directly be followed by a downfield shift for the complex. The vanadium catechol complexes were used in this work because the 51V is a half-integer quadrupolar nucleus whose NMR observables are highly sensitive to the local environment. However, the results are general and could be extended to other redox active complexes that exhibit similar coordination chemistry as the vanadium catechol complexes. PMID:21842875

An empirical method for determining average soil infiltration rates and runoff, Powder River structural basin, Wyoming

USGS Publications Warehouse

Rankl, James G.

1982-01-01

This report describes a method to estimate infiltration rates of soils for use in estimating runoff from small basins. Average rainfall intensity is plotted against storm duration on log-log paper. All rainfall events are designated as having either runoff or nonrunoff. A power-decay-type curve is visually fitted to separate the two types of rainfall events. This separation curve is an incipient-ponding curve and its equation describes infiltration parameters for a soil. For basins with more than one soil complex, only the incipient-ponding curve for the soil complex with the lowest infiltration rate can be defined using the separation technique. Incipient-ponding curves for soils with infiltration rates greater than the lowest curve are defined by ranking the soils according to their relative permeabilities and optimizing the curve position. A comparison of results for six basins produced computed total runoff for all events used ranging from 16.6 percent less to 2.3 percent more than measured total runoff. (USGS)

Protection of ascorbic acid from copper(II)-catalyzed oxidative degradation in the presence of flavonoids: quercetin, catechin and morin.

PubMed

Beker, Bilge Yildoğan; Sönmezoğlu, Inci; Imer, Filiz; Apak, Reşat

2011-08-01

Protection of ascorbic acid (AA) (vitamin C) from Cu(II)-catalyzed autoxidation is an important aspect of antioxidant chemistry. The autoxidation of AA in the absence and presence of Cu(II) ions was investigated in aerated solution at room temperature and I = 0.1 ionic strength (KNO(3)); the effects of three different flavonoids of similar structure (quercetin, morin and catechin) and their mixtures on the AA system were studied. The concentration of unoxidized AA remaining in solution was measured with the modified cupric ion reducing antioxidant capacity spectrophotometric method. The Cu(II)-catalyzed oxidation at pH 4.5 followed first-order kinetics with respect to AA concentration. Catalytic autoxidation of AA was inhibited to a greater extent by stable quercetin and morin complexes of Cu(II) than by catechin complex. The inhibitive effectiveness order of mixtures gives information about possible synergistic or antagonistic combinations of flavonoid antioxidants, which should be further confirmed with other antioxidant tests.

[Mental Health Centers, in regard to professional confidentiality and privacy].

PubMed

Catanesi, Roberto; Carabellese, Felice

2012-01-01

Maintaining privacy in the complex operative reality of public psychiatric services is not easy. Many operational doubts arise and psychiatrists encounter difficulties in application of the privacy norms, partly due to the clinical and treatment peculiarities of the psychiatric domain and partly to organizational and structural limits. The risk addressed in this work is that the apparent complexity of the privacy norms may be perceived by psychiatrists in the public sector simply as a further bureaucratization of the doctor-patient relationship rather than as an opportunity to institute greater safeguards of patients' rights. Hence, the Authors aim to clarify the key points of the law, integrating them with the classic issues of confidentiality, in order to outline the goals, provide suggestions as to how best to adapt practice to conform to these norms, and highlight ways to simplify procedures. The Authors conclude by expressing the hope that the principles embodied in the privacy norms may become an integral part of the cultural heritage of territorial psychiatric services.

Using CV-GLUE procedure in analysis of wetland model predictive uncertainty.

PubMed

Huang, Chun-Wei; Lin, Yu-Pin; Chiang, Li-Chi; Wang, Yung-Chieh

2014-07-01

This study develops a procedure that is related to Generalized Likelihood Uncertainty Estimation (GLUE), called the CV-GLUE procedure, for assessing the predictive uncertainty that is associated with different model structures with varying degrees of complexity. The proposed procedure comprises model calibration, validation, and predictive uncertainty estimation in terms of a characteristic coefficient of variation (characteristic CV). The procedure first performed two-stage Monte-Carlo simulations to ensure predictive accuracy by obtaining behavior parameter sets, and then the estimation of CV-values of the model outcomes, which represent the predictive uncertainties for a model structure of interest with its associated behavior parameter sets. Three commonly used wetland models (the first-order K-C model, the plug flow with dispersion model, and the Wetland Water Quality Model; WWQM) were compared based on data that were collected from a free water surface constructed wetland with paddy cultivation in Taipei, Taiwan. The results show that the first-order K-C model, which is simpler than the other two models, has greater predictive uncertainty. This finding shows that predictive uncertainty does not necessarily increase with the complexity of the model structure because in this case, the more simplistic representation (first-order K-C model) of reality results in a higher uncertainty in the prediction made by the model. The CV-GLUE procedure is suggested to be a useful tool not only for designing constructed wetlands but also for other aspects of environmental management. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Complexity of One-Step Equations

ERIC Educational Resources Information Center

Ngu, Bing

2014-01-01

An analysis of one-step equations from a cognitive load theory perspective uncovers variation within one-step equations. The complexity of one-step equations arises from the element interactivity across the operational and relational lines. The higher the number of operational and relational lines, the greater the complexity of the equations.…

Alpha-ketoglutarate dehydrogenase complex-dependent succinylation of proteins in neurons and neuronal cell lines

PubMed Central

Gibson, Gary E.; Xu, Hui; Chen, Huan-Lian; Chen, Wei; Denton, Travis; Zhang, Sheng

2015-01-01

Reversible post-translation modifications of proteins are common in all cells and appear to regulate many processes. Nevertheless, the enzyme(s) responsible for the alterations and the significance of the modification are largely unknown. Succinylation of proteins occurs and causes large changes in the structure of proteins; however, the source of the succinyl groups, the targets, and the consequences of these modifications on other proteins are unknown. These studies focused on succinylation of mitochondrial proteins. The results demonstrate that the α-ketoglutarate dehydrogenase complex (KGDHC) can serve as a trans-succinylase that mediates succinylation in an α-ketoglutarate-dependent manner. Inhibition of KGDHC reduced suc-cinylation of both cytosolic and mitochondrial proteins in cultured neurons and in a neuronal cell line. Purified KGDHC can succinylate multiple proteins including other enzymes of the tricarboxylic acid (TCA) cycle leading to modification of their activity. Inhibition of KGDHC also modifies acetylation by modifying the pyruvate dehydrogenase complex. The much greater effectiveness of KGDHC than succinyl CoA suggests that the catalysis due to the E2k suc-cinyltransferase is important. Succinylation appears to be a major signaling system and it can be mediated by KGDHC. PMID:25772995

Adaptive and selective seed abortion reveals complex conditional decision making in plants.

PubMed

Meyer, Katrin M; Soldaat, Leo L; Auge, Harald; Thulke, Hans-Hermann

2014-03-01

Behavior is traditionally attributed to animals only. Recently, evidence for plant behavior is accumulating, mostly from plant physiological studies. Here, we provide ecological evidence for complex plant behavior in the form of seed abortion decisions conditional on internal and external cues. We analyzed seed abortion patterns of barberry plants exposed to seed parasitism and different environmental conditions. Without abortion, parasite infestation of seeds can lead to loss of all seeds in a fruit. We statistically tested a series of null models with Monte Carlo simulations to establish selectivity and adaptiveness of the observed seed abortion patterns. Seed abortion was more frequent in parasitized fruits and fruits from dry habitats. Surprisingly, seed abortion occurred with significantly greater probability if there was a second intact seed in the fruit. This strategy provides a fitness benefit if abortion can prevent a sibling seed from coinfestation and if nonabortion of an infested but surviving single seed saves resources invested in the fruit coat. Ecological evidence for complex decision making in plants thus includes a structural memory (the second seed), simple reasoning (integration of inner and outer conditions), conditional behavior (abortion), and anticipation of future risks (seed predation).

Cross-activating c-Met/β1 integrin complex drives metastasis and invasive resistance in cancer

PubMed Central

Jahangiri, Arman; Nguyen, Alan; Sidorov, Maxim K.; Yagnik, Garima; Rick, Jonathan; Han, Sung Won; Chen, William; Flanigan, Patrick M.; Schneidman-Duhovny, Dina; Mascharak, Smita; De Lay, Michael; Imber, Brandon; Park, Catherine C.; Matsumoto, Kunio; Lu, Kan; Bergers, Gabriele; Sali, Andrej; Weiss, William A.

2017-01-01

The molecular underpinnings of invasion, a hallmark of cancer, have been defined in terms of individual mediators but crucial interactions between these mediators remain undefined. In xenograft models and patient specimens, we identified a c-Met/β1 integrin complex that formed during significant invasive oncologic processes: breast cancer metastases and glioblastoma invasive resistance to antiangiogenic VEGF neutralizing antibody, bevacizumab. Inducing c-Met/β1 complex formation through an engineered inducible heterodimerization system promoted features crucial to overcoming stressors during metastases or antiangiogenic therapy: migration in the primary site, survival under hypoxia, and extravasation out of circulation. c-Met/β1 complex formation was up-regulated by hypoxia, while VEGF binding VEGFR2 sequestered c-Met and β1 integrin, preventing their binding. Complex formation promoted ligand-independent receptor activation, with integrin-linked kinase phosphorylating c-Met and crystallography revealing the c-Met/β1 complex to maintain the high-affinity β1 integrin conformation. Site-directed mutagenesis verified the necessity for c-Met/β1 binding of amino acids predicted by crystallography to mediate their extracellular interaction. Far-Western blotting and sequential immunoprecipitation revealed that c-Met displaced α5 integrin from β1 integrin, creating a complex with much greater affinity for fibronectin (FN) than α5β1. Thus, tumor cells adapt to microenvironmental stressors induced by metastases or bevacizumab by coopting receptors, which normally promote both cell migration modes: chemotaxis, movement toward concentrations of environmental chemoattractants, and haptotaxis, movement controlled by the relative strengths of peripheral adhesions. Tumor cells then redirect these receptors away from their conventional binding partners, forming a powerful structural c-Met/β1 complex whose ligand-independent cross-activation and robust affinity for FN drive invasive oncologic processes. PMID:28973887

Whole-brain analytic measures of network communication reveal increased structure-function correlation in right temporal lobe epilepsy.

PubMed

Wirsich, Jonathan; Perry, Alistair; Ridley, Ben; Proix, Timothée; Golos, Mathieu; Bénar, Christian; Ranjeva, Jean-Philippe; Bartolomei, Fabrice; Breakspear, Michael; Jirsa, Viktor; Guye, Maxime

2016-01-01

The in vivo structure-function relationship is key to understanding brain network reorganization due to pathologies. This relationship is likely to be particularly complex in brain network diseases such as temporal lobe epilepsy, in which disturbed large-scale systems are involved in both transient electrical events and long-lasting functional and structural impairments. Herein, we estimated this relationship by analyzing the correlation between structural connectivity and functional connectivity in terms of analytical network communication parameters. As such, we targeted the gradual topological structure-function reorganization caused by the pathology not only at the whole brain scale but also both in core and peripheral regions of the brain. We acquired diffusion (dMRI) and resting-state fMRI (rsfMRI) data in seven right-lateralized TLE (rTLE) patients and fourteen healthy controls and analyzed the structure-function relationship by using analytical network communication metrics derived from the structural connectome. In rTLE patients, we found a widespread hypercorrelated functional network. Network communication analysis revealed greater unspecific branching of the shortest path (search information) in the structural connectome and a higher global correlation between the structural and functional connectivity for the patient group. We also found evidence for a preserved structural rich-club in the patient group. In sum, global augmentation of structure-function correlation might be linked to a smaller functional repertoire in rTLE patients, while sparing the central core of the brain which may represent a pathway that facilitates the spread of seizures.

Mature and old-growth riparian forests: structure, dynamics, and effects on Adirondack stream habitats.

PubMed

Keeton, William S; Kraft, Clifford E; Warren, Dana R

2007-04-01

Riparian forests regulate linkages between terrestrial and aquatic ecosystems, yet relationships among riparian forest development, stand structure, and stream habitats are poorly understood in many temperate deciduous forest systems. Our research has (1) described structural attributes associated with old-growth riparian forests and (2) assessed linkages between these characteristics and in-stream habitat structure. The 19 study sites were located along predominantly first- and second-order streams in northern hardwood-conifer forests in the Adirondack Mountains of New York (U.S.A.). Sites were classified as mature forest (6 sites), mature with remnant old-growth trees (3 sites), and old-growth (10 sites). Forest-structure attributes were measured over stream channels and at varying distances from each bank. In-stream habitat features such as large woody debris (LWD), pools, and boulders were measured in each stream reach. Forest structure was examined in relation to stand age using multivariate techniques, ANOVA, and linear regression. We investigated linkages between forest structure and stream characteristics using similar methods, preceded by information-theoretic modeling (AIC). Old-growth riparian forest structure is more complex than that found in mature forests and exhibits significantly greater accumulations of aboveground tree biomass, both living and dead. In-stream LWD volumes were significantly (alpha = 0.05) greater at old-growth sites (200 m3/ha) compared to mature sites (34 m3/ha) and were strongly related to the basal area of adjacent forests. In-stream large-log densities correlated strongly with debris-dam densities. AIC models that included large-log density, debris-dam density, boulder density, and bankfull width had the most support for predicting pool density. There were higher proportions of LWD-formed pools relative to boulder-formed pools at old-growth sites as compared to mature sites. Old-growth riparian forests provide in-stream habitat features that have not been widely recognized in eastern North America, representing a potential benefit from late-successional riparian forest management and conservation. Riparian management practices (including buffer delineation and restorative silvicultural approaches) that emphasize development and maintenance of late-successional characteristics are recommended where the associated in-stream effects are desired.

Hierarchical population structure in greater sage-grouse provides insight into management boundary delineation

Treesearch

Todd B. Cross; David E. Naugle; John C. Carlson; Michael K. Schwartz

2016-01-01

Understanding population structure is important for guiding ongoing conservation and restoration efforts. The greater sage-grouse (Centrocercus urophasianus) is a species of concern distributed across 1.2 million km2 of western North America. We genotyped 1499 greater sagegrouse from 297 leks across Montana, North Dakota and South Dakota using a 15 locus...

Extraribosomal L13a Is a Specific Innate Immune Factor for Antiviral Defense

PubMed Central

Poddar, Darshana; Basu, Abhijit; Kour, Ravinder; Verbovetskaya, Valentina

2014-01-01

ABSTRACT We report a novel extraribosomal innate immune function of mammalian ribosomal protein L13a, whereby it acts as an antiviral agent. We found that L13a is released from the 60S ribosomal subunit in response to infection by respiratory syncytial virus (RSV), an RNA virus of the Pneumovirus genus and a serious lung pathogen. Unexpectedly, the growth of RSV was highly enhanced in L13a-knocked-down cells of various lineages as well as in L13a knockout macrophages from mice. In all L13a-deficient cells tested, translation of RSV matrix (M) protein was specifically stimulated, as judged by a greater abundance of M protein and greater association of the M mRNA with polyribosomes, while general translation was unaffected. In silico RNA folding analysis and translational reporter assays revealed a putative hairpin in the 3′untranslated region (UTR) of M mRNA with significant structural similarity to the cellular GAIT (gamma-activated inhibitor of translation) RNA hairpin, previously shown to be responsible for assembling a large, L13a-containing ribonucleoprotein complex that promoted translational silencing in gamma interferon (IFN-γ)-activated myeloid cells. However, RNA-protein interaction studies revealed that this complex, which we named VAIT (respiratory syncytial virus-activated inhibitor of translation) is functionally different from the GAIT complex. VAIT is the first report of an extraribosomal L13a-mediated, IFN-γ-independent innate antiviral complex triggered in response to virus infection. We provide a model in which the VAIT complex strongly hinders RSV replication by inhibiting the translation of the rate-limiting viral M protein, which is a new paradigm in antiviral defense. IMPORTANCE The innate immune mechanisms of host cells are diverse in nature and act as a broad-spectrum cellular defense against viruses. Here, we report a novel innate immune mechanism functioning against respiratory syncytial virus (RSV), in which the cellular ribosomal protein L13a is released from the large ribosomal subunit soon after infection and inhibits the translation of a specific viral mRNA, namely, that of the matrix protein M. Regarding its mechanism, we show that the recognition of a specific secondary structure in the 3′ untranslated region of the M mRNA leads to translational arrest of the mRNA. We also show that the level of M protein in the infected cell is rate limiting for viral morphogenesis, providing a rationale for L13a to target the M mRNA for suppression of RSV growth. Translational silencing of a viral mRNA by a deployed ribosomal protein is a new paradigm in innate immunity. PMID:24899178

Extraribosomal l13a is a specific innate immune factor for antiviral defense.

PubMed

Mazumder, Barsanjit; Poddar, Darshana; Basu, Abhijit; Kour, Ravinder; Verbovetskaya, Valentina; Barik, Sailen

2014-08-01

We report a novel extraribosomal innate immune function of mammalian ribosomal protein L13a, whereby it acts as an antiviral agent. We found that L13a is released from the 60S ribosomal subunit in response to infection by respiratory syncytial virus (RSV), an RNA virus of the Pneumovirus genus and a serious lung pathogen. Unexpectedly, the growth of RSV was highly enhanced in L13a-knocked-down cells of various lineages as well as in L13a knockout macrophages from mice. In all L13a-deficient cells tested, translation of RSV matrix (M) protein was specifically stimulated, as judged by a greater abundance of M protein and greater association of the M mRNA with polyribosomes, while general translation was unaffected. In silico RNA folding analysis and translational reporter assays revealed a putative hairpin in the 3'untranslated region (UTR) of M mRNA with significant structural similarity to the cellular GAIT (gamma-activated inhibitor of translation) RNA hairpin, previously shown to be responsible for assembling a large, L13a-containing ribonucleoprotein complex that promoted translational silencing in gamma interferon (IFN-γ)-activated myeloid cells. However, RNA-protein interaction studies revealed that this complex, which we named VAIT (respiratory syncytial virus-activated inhibitor of translation) is functionally different from the GAIT complex. VAIT is the first report of an extraribosomal L13a-mediated, IFN-γ-independent innate antiviral complex triggered in response to virus infection. We provide a model in which the VAIT complex strongly hinders RSV replication by inhibiting the translation of the rate-limiting viral M protein, which is a new paradigm in antiviral defense. The innate immune mechanisms of host cells are diverse in nature and act as a broad-spectrum cellular defense against viruses. Here, we report a novel innate immune mechanism functioning against respiratory syncytial virus (RSV), in which the cellular ribosomal protein L13a is released from the large ribosomal subunit soon after infection and inhibits the translation of a specific viral mRNA, namely, that of the matrix protein M. Regarding its mechanism, we show that the recognition of a specific secondary structure in the 3' untranslated region of the M mRNA leads to translational arrest of the mRNA. We also show that the level of M protein in the infected cell is rate limiting for viral morphogenesis, providing a rationale for L13a to target the M mRNA for suppression of RSV growth. Translational silencing of a viral mRNA by a deployed ribosomal protein is a new paradigm in innate immunity. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Frameworks for evaluating health research capacity strengthening: a qualitative study

PubMed Central

2013-01-01

Background Health research capacity strengthening (RCS) projects are often complex and hard to evaluate. In order to inform health RCS evaluation efforts, we aimed to describe and compare key characteristics of existing health RCS evaluation frameworks: their process of development, purpose, target users, structure, content and coverage of important evaluation issues. A secondary objective was to explore what use had been made of the ESSENCE framework, which attempts to address one such issue: harmonising the evaluation requirements of different funders. Methods We identified and analysed health RCS evaluation frameworks published by seven funding agencies between 2004 and 2012, using a mixed methods approach involving structured qualitative analyses of documents, a stakeholder survey and consultations with key contacts in health RCS funding agencies. Results The frameworks were intended for use predominantly by the organisations themselves, and most were oriented primarily towards funders’ internal organisational performance requirements. The frameworks made limited reference to theories that specifically concern RCS. Generic devices, such as logical frameworks, were typically used to document activities, outputs and outcomes, but with little emphasis on exploring underlying assumptions or contextual constraints. Usage of the ESSENCE framework appeared limited. Conclusions We believe that there is scope for improving frameworks through the incorporation of more accessible information about how to do evaluation in practice; greater involvement of stakeholders, following evaluation capacity building principles; greater emphasis on explaining underlying rationales of frameworks; and structuring frameworks so that they separate generic and project-specific aspects of health RCS evaluation. The third and fourth of these improvements might assist harmonisation. PMID:24330628

Fish as indicators of disturbance in streams used for snorkeling activities in a tourist region.

PubMed

Teresa, Fabricio Barreto; Romero, Renato de Mei; Casatti, Lilian; Sabino, José

2011-05-01

A set of metrics that reflect various aspects of population and fish community structure in streams used for snorkeling was evaluated in the tourist region of Bodoquena Plateau, Brazil, with the purpose of biomonitoring the impacts of such activities. Observations were made while snorkeling in two sites (active = with tourism; inactive = without tourism) and along the gradient of daily tourist activity (before, during and after the passage of tourists) in two streams. Five metrics discriminated active from inactive sites: (i) the abundance of Crenicichla lepidota and (ii) the incidence of reproductive activity in Crenicichla lepidota which were greater in inactive sites, regardless the gradient of daily tourist activity; (iii) the feeding pattern of Prochilodus lineatus, which differed among sites and along the gradient of daily tourist activity; (iv) the abundance of Moenkhausia bonita, which was higher in the active sites and significantly increased along the gradient of daily tourist activity in one stream but decrease along the gradient in other stream; (v) the abundance of Hyphessobrycon eques, which was greater in inactive sites, regardless the gradient of daily tourist activity. With the exception of metric "iv", the metrics were mediated by the reduction in habitat structural complexity due to snorkeling disturbance. The definition of these metrics is relevant because the degradation of ecosystem structural elements is one of the main impacts of recreational activities on aquatic environments. The easy recognition of target species and high water transparency throughout the year ensures the feasibility of these metrics in monitoring programs and may be applied by technicians after quick guides and training.

Fish as Indicators of Disturbance in Streams Used for Snorkeling Activities in a Tourist Region

NASA Astrophysics Data System (ADS)

Teresa, Fabricio Barreto; Romero, Renato De Mei; Casatti, Lilian; Sabino, José

2011-05-01

A set of metrics that reflect various aspects of population and fish community structure in streams used for snorkeling was evaluated in the tourist region of Bodoquena Plateau, Brazil, with the purpose of biomonitoring the impacts of such activities. Observations were made while snorkeling in two sites (active = with tourism; inactive = without tourism) and along the gradient of daily tourist activity (before, during and after the passage of tourists) in two streams. Five metrics discriminated active from inactive sites: (i) the abundance of Crenicichla lepidota and (ii) the incidence of reproductive activity in Crenicichla lepidota which were greater in inactive sites, regardless the gradient of daily tourist activity; (iii) the feeding pattern of Prochilodus lineatus, which differed among sites and along the gradient of daily tourist activity; (iv) the abundance of Moenkhausia bonita, which was higher in the active sites and significantly increased along the gradient of daily tourist activity in one stream but decrease along the gradient in other stream; (v) the abundance of Hyphessobrycon eques, which was greater in inactive sites, regardless the gradient of daily tourist activity. With the exception of metric "iv", the metrics were mediated by the reduction in habitat structural complexity due to snorkeling disturbance. The definition of these metrics is relevant because the degradation of ecosystem structural elements is one of the main impacts of recreational activities on aquatic environments. The easy recognition of target species and high water transparency throughout the year ensures the feasibility of these metrics in monitoring programs and may be applied by technicians after quick guides and training.

Post-Fire Spatial Patterns of Soil Nitrogen Mineralization and Microbial Abundance

PubMed Central

Smithwick, Erica A. H.; Naithani, Kusum J.; Balser, Teri C.; Romme, William H.; Turner, Monica G.

2012-01-01

Stand-replacing fires influence soil nitrogen availability and microbial community composition, which may in turn mediate post-fire successional dynamics and nutrient cycling. However, fires create patchiness at both local and landscape scales and do not result in consistent patterns of ecological dynamics. The objectives of this study were to (1) quantify the spatial structure of microbial communities in forest stands recently affected by stand-replacing fire and (2) determine whether microbial variables aid predictions of in situ net nitrogen mineralization rates in recently burned stands. The study was conducted in lodgepole pine (Pinus contorta var. latifolia) and Engelmann spruce/subalpine fir (Picea engelmannii/Abies lasiocarpa) forest stands that burned during summer 2000 in Greater Yellowstone (Wyoming, USA). Using a fully probabilistic spatial process model and Bayesian kriging, the spatial structure of microbial lipid abundance and fungi-to-bacteria ratios were found to be spatially structured within plots two years following fire (for most plots, autocorrelation range varied from 1.5 to 10.5 m). Congruence of spatial patterns among microbial variables, in situ net N mineralization, and cover variables was evident. Stepwise regression resulted in significant models of in situ net N mineralization and included variables describing fungal and bacterial abundance, although explained variance was low (R2<0.29). Unraveling complex spatial patterns of nutrient cycling and the biotic factors that regulate it remains challenging but is critical for explaining post-fire ecosystem function, especially in Greater Yellowstone, which is projected to experience increased fire frequencies by mid 21st Century. PMID:23226324

In Silico Analysis for the Study of Botulinum Toxin Structure

NASA Astrophysics Data System (ADS)

Suzuki, Tomonori; Miyazaki, Satoru

2010-01-01

Protein-protein interactions play many important roles in biological function. Knowledge of protein-protein complex structure is required for understanding the function. The determination of protein-protein complex structure by experimental studies remains difficult, therefore computational prediction of protein structures by structure modeling and docking studies is valuable method. In addition, MD simulation is also one of the most popular methods for protein structure modeling and characteristics. Here, we attempt to predict protein-protein complex structure and property using some of bioinformatic methods, and we focus botulinum toxin complex as target structure.

Evaluation of protein-protein docking model structures using all-atom molecular dynamics simulations combined with the solution theory in the energy representation

NASA Astrophysics Data System (ADS)

Takemura, Kazuhiro; Guo, Hao; Sakuraba, Shun; Matubayasi, Nobuyuki; Kitao, Akio

2012-12-01

We propose a method to evaluate binding free energy differences among distinct protein-protein complex model structures through all-atom molecular dynamics simulations in explicit water using the solution theory in the energy representation. Complex model structures are generated from a pair of monomeric structures using the rigid-body docking program ZDOCK. After structure refinement by side chain optimization and all-atom molecular dynamics simulations in explicit water, complex models are evaluated based on the sum of their conformational and solvation free energies, the latter calculated from the energy distribution functions obtained from relatively short molecular dynamics simulations of the complex in water and of pure water based on the solution theory in the energy representation. We examined protein-protein complex model structures of two protein-protein complex systems, bovine trypsin/CMTI-1 squash inhibitor (PDB ID: 1PPE) and RNase SA/barstar (PDB ID: 1AY7), for which both complex and monomer structures were determined experimentally. For each system, we calculated the energies for the crystal complex structure and twelve generated model structures including the model most similar to the crystal structure and very different from it. In both systems, the sum of the conformational and solvation free energies tended to be lower for the structure similar to the crystal. We concluded that our energy calculation method is useful for selecting low energy complex models similar to the crystal structure from among a set of generated models.

Evaluation of protein-protein docking model structures using all-atom molecular dynamics simulations combined with the solution theory in the energy representation.

PubMed

Takemura, Kazuhiro; Guo, Hao; Sakuraba, Shun; Matubayasi, Nobuyuki; Kitao, Akio

2012-12-07

We propose a method to evaluate binding free energy differences among distinct protein-protein complex model structures through all-atom molecular dynamics simulations in explicit water using the solution theory in the energy representation. Complex model structures are generated from a pair of monomeric structures using the rigid-body docking program ZDOCK. After structure refinement by side chain optimization and all-atom molecular dynamics simulations in explicit water, complex models are evaluated based on the sum of their conformational and solvation free energies, the latter calculated from the energy distribution functions obtained from relatively short molecular dynamics simulations of the complex in water and of pure water based on the solution theory in the energy representation. We examined protein-protein complex model structures of two protein-protein complex systems, bovine trypsin/CMTI-1 squash inhibitor (PDB ID: 1PPE) and RNase SA/barstar (PDB ID: 1AY7), for which both complex and monomer structures were determined experimentally. For each system, we calculated the energies for the crystal complex structure and twelve generated model structures including the model most similar to the crystal structure and very different from it. In both systems, the sum of the conformational and solvation free energies tended to be lower for the structure similar to the crystal. We concluded that our energy calculation method is useful for selecting low energy complex models similar to the crystal structure from among a set of generated models.

The Effect of Sensor Performance on Safe Minefield Transit

DTIC Science & Technology

2002-12-01

the results of the simpler model are not good approximations of the results obtained with the more complex model, suggesting that even greater complexity in maneuver modeling may be desirable for some purposes.

Microstructure of β-Sitosterol:γ-Oryzanol Edible Organogels.

PubMed

Matheson, Andrew B; Koutsos, Vasileios; Dalkas, Georgios; Euston, Stephen; Clegg, Paul

2017-05-09

Rheology and atomic force microscopy (AFM) were employed to examine the microstructure of β-sitosterol:γ-oryzanol organogels in sunflower oil. Using time-resolved rheology, we followed gel formation, paying specific attention to the fibril aggregation process, which had not been studied in detail previously for this system. Using AFM, we observed gel structures directly and obtained detailed information on the gel structure, far exceeding previous studies. Our analysis suggests that though gels are formed by the self-assembly and aggregation of one-dimensional fibrils, the manner in which these fibrils aggregate into ribbons results in complex structures of higher dimensionality. We emphasize that it is a surprise to find ribbons and not twisted strands. Comparing AFM images of 10% w/w and 20% w/w gelator systems, we observed differences in the degree of branching which are consistent with the rheology. We also observed the individual self-assembled fibrils which make up these gels with much greater clarity than in previous microscopy studies, and the fibril diameters of ∼9.8 nm we measured agree excellently with those obtained from existing small-angle neutron scattering data. These results provide new insight into the structure and formation kinetics of this important organogel system.

Categorizing words through semantic memory navigation

NASA Astrophysics Data System (ADS)

Borge-Holthoefer, J.; Arenas, A.

2010-03-01

Semantic memory is the cognitive system devoted to storage and retrieval of conceptual knowledge. Empirical data indicate that semantic memory is organized in a network structure. Everyday experience shows that word search and retrieval processes provide fluent and coherent speech, i.e. are efficient. This implies either that semantic memory encodes, besides thousands of words, different kind of links for different relationships (introducing greater complexity and storage costs), or that the structure evolves facilitating the differentiation between long-lasting semantic relations from incidental, phenomenological ones. Assuming the latter possibility, we explore a mechanism to disentangle the underlying semantic backbone which comprises conceptual structure (extraction of categorical relations between pairs of words), from the rest of information present in the structure. To this end, we first present and characterize an empirical data set modeled as a network, then we simulate a stochastic cognitive navigation on this topology. We schematize this latter process as uncorrelated random walks from node to node, which converge to a feature vectors network. By doing so we both introduce a novel mechanism for information retrieval, and point at the problem of category formation in close connection to linguistic and non-linguistic experience.

Structural characterization of viral epitopes recognized by broadly cross-reactive antibodies.

PubMed

Lee, Peter S; Wilson, Ian A

2015-01-01

Influenza hemagglutinin (HA) is the major surface glycoprotein on influenza viruses and mediates viral attachment and subsequent fusion with host cells. The HA is the major target of the immune response, but due to its high level of variability, as evidenced by substantial antigenic diversity, it had been historically considered to elicit only a narrow, strain-specific antibody response. However, a recent explosion in the discovery of broadly neutralizing antibodies (bnAbs) to influenza virus has identified two major supersites of vulnerability on the HA through structural characterization of HA-antibody complexes. These commonly targeted epitopes are involved with receptor binding as well as the fusion machinery and, hence, are functionally conserved and less prone to mutation. These bnAbs can neutralize viruses by blocking infection or the spread of infection by preventing progeny release. Structural analyses of these bnAbs show they exhibit striking similarities and trends in recognition of the HA and use recurring recognition motifs, despite substantial differences in their germline genes. This information can be utilized in design of novel therapeutics as well as in immunogens for improved vaccines with greater breadth and efficacy.

Preparation of anticoagulant PyC biomaterials with super-hydrophobic surface.

PubMed

Ze, Wang; Wen-Sheng, Tan; Ye-Xia; Ming, Zhang; Xiao-Ping, Li; Jian-Guo, Qiu; Xiao-Hong, Yang

2018-01-01

Pyrolytic carbon (PyC) is a kind of biomaterial which is chemically inert and has excellent biocompatibility. In order to obtain a super-hydrophobic PyC surface to improve anticoagulation and inhibit thrombus, this study prepares grating pair structure, microhole array structure, helix structure on PyC surface by nanoseconds laser etching. Rod-like ZnO film and ball-like ZnO film are prepared on the PyC surface by the hydrothermal method; polyvinyl pyrrolidone (PVP) nanofiber film and PVP/TiO 2 complex nanofiber film are prepared on the PyC surface by the electrospinning method; the PyC surface is silanized. Finally, surface microstructure and surface energy are characterized by scanning electron microscopy and contact angle meter (OCA20, German DataPhysics Co.). The periodical microstructures are formed respectively by nanoseconds laser etching. The surface roughness is increased by the hydrothermal and electrospinning method. Through infiltration experiment on rough and smooth PyC surfaces, rough PyC surface with microstructure is super-hydrophobic and has greater than 150° contact angle, which decreases blood flow resistance and inhibits thrombus.

Computational Discovery of New Materials Under Pressure

NASA Astrophysics Data System (ADS)

Zurek, Eva

The pressure variable opens the door towards the synthesis of materials with unique properties, ie. superconductivity, hydrogen storage media, high-energy density and superhard materials, to name a few. Indeed, recently superconductivity has been observed below 203 K and 103 K in samples of compressed sulfur dihydride and phosphine, respectively. Under pressure elements that would not normally combine may form stable compounds, or may mix in novel proportions. As a result using our chemical intuition developed at 1 atm to theoretically predict stable phases is bound to fail. In order to enable our search for superconducting hydrogen-rich systems under pressure, we have developed XtalOpt, an open-source evolutionary algorithm for crystal structure prediction. New advances in XtalOpt that enable the prediction of unit cells with greater complexity will be described. XtalOpt has been employed to find the most stable structures of hydrides with unique stoichiometries under pressure. The electronic structure and bonding of the predicted phases has been analyzed by detailed first-principles calculations based on density functional theory. The results of our computational experiments are helping us to build chemical and physical intuition for compressed solids.

Mix-and-match nanobiosensor design: Logical and spatial programming of biosensors using self-assembled DNA nanostructures.

PubMed

Liu, Ying; Kumar, Sriram; Taylor, Rebecca E

2018-04-06

The evergrowing need to understand and engineer biological and biochemical mechanisms has led to the emergence of the field of nanobiosensing. Structural DNA nanotechnology, encompassing methods such as DNA origami and single-stranded tiles, involves the base pairing-driven knitting of DNA into discrete one-, two-, and three-dimensional shapes at nanoscale. Such nanostructures enable a versatile design and fabrication of nanobiosensors. These systems benefit from DNA's programmability, inherent biocompatibility, and the ability to incorporate and organize functional materials such as proteins and metallic nanoparticles. In this review, we present a mix-and-match taxonomy and approach to designing nanobiosensors in which the choices of bioanalyte and transduction mechanism are fully independent of each other. We also highlight opportunities for greater complexity and programmability of these systems that are built using structural DNA nanotechnology. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Diagnostic Tools > Biosensing Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures Nanotechnology Approaches to Biology > Nanoscale Systems in Biology. © 2018 Wiley Periodicals, Inc.

Structural features of soluble cereal arabinoxylan fibers associated with a slow rate of in vitro fermentation by human fecal microbiota.

PubMed

Rumpagaporn, Pinthip; Reuhs, Brad L; Kaur, Amandeep; Patterson, John A; Keshavarzian, Ali; Hamaker, Bruce R

2015-10-05

Most soluble dietary fibers ferment rapidly in the proximal colon, potentially causing discomfort and poor tolerability. Alkali-extracted arabinoxylan isolates from corn, wheat, rice and sorghum brans were prepared, through hydrolysis (except sorghum) and ethanol fractionation, to have a broad range of initial fermentation rates, and their linkage patterns were determined to understand structural aspects related to slow fermentation rate. They were all highly branched polymers with degree of substitution greater than 64%. There was no relationship of molecular mass, arabinose:xylose ratio, or degree of substitution to fermentation rate patterns. Slow fermenting wheat and corn arabinoxylans had much higher amount of terminal xylose in branches than fast fermenting rice and sorghum arabinoxylans. The slowest fermenting wheat arabinoxylan additionally contained a complex trisaccharide side chain with two arabinoses linked at the O-2 and O-3 positions of an arabinose that is O-2 linked to the xylan backbone. Structural features were proposed for tolerable slowly fermentable arabinoxylan with possible beneficial fermentation function into the distal colon. Copyright © 2015 Elsevier Ltd. All rights reserved.

Aulacogens and aulacogeosynclines: Regularities in setting and evolution

NASA Astrophysics Data System (ADS)

Milanovsky, E. E.

1992-12-01

Aulacogens and aulacogeosynclinal zones represent intra-continental palaeorifts and inverted palaeorifts. They were formed in the process of the break-up of continents during the Late Proterozoic. Inversion of such basins occurred variably during the Baikalian, Caledonian, Hercynian and Alpine orogenic cycles in response to the build-up of intraplate compressional stresses emanating from orogenic belts. Aulacogens were first recognized on the stable Russian Platform where they correspond to linear, graben type depressions filled with Proterozoic sediments, often buried beneath a thick cover of Palaeozoic and younger sediments. Some aulacogens have experienced a short period of reactivation during the Palaeozoic. Aulacogeosynclines differ from the genetically related aulacogens by their greater dimensions and the amount of lithospheric extension that can go to the extent of opening of small ocean basins; consequently they are characterized by a greater degree of destruction of the continental crust, the depth of subsidence and the complexity of their post-rift development which commonly terminates with their compressional deformation, giving rise to the development of intracontinental linear folded and thrusted structures, frequently associated with low-grade metamorphism and small intrusions. Many ancient platforms are characterized by aulacogens; metaplatforms are dissected by aulacogens and aulacogeosynclines, whereas geosynclinal troughs are the precursors of geosynclinal mobil belts. Aulacogens, aulacogeosynclines and geosynclinal troughs represent a group of negative, linear structures which are characterized by an increasing degree of crustal destruction during rifting processes and increasing mobility during lithospheric contraction.

Femtosecond fiber laser additive manufacturing and welding for 3D manufacturing

NASA Astrophysics Data System (ADS)

Huang, Huan; Nie, Bai; Wan, Peng; Yang, Lih-Mei; Bai, Shuang; Liu, Jian

2015-03-01

Due to the unique ultra-short pulse duration and high peak power, femtosecond (fs) laser has emerged as a powerful tool for many applications but has rarely been studied for 3D printing. In this paper, welding of both bulk and powder materials is demonstrated for the first time by using high energy and high repetition rate fs fiber lasers. It opens up new scenarios and opportunities for 3D printing with the following advantages - greater range of materials especially with high melting temperature, greater-than-ever level of precision (sub-micron) and less heat-affected-zone (HAZ). Mechanical properties (strength and hardness) and micro-structures (grain size) of the fabricated parts are investigated. For dissimilar materials bulk welding, good welding quality with over 210 MPa tensile strength is obtained. Also full melting of the micron-sized refractory powders with high melting temperature (above 3000 degree C) is achieved for the first time. 3D parts with shapes like ring and cube are fabricated. Not only does this study explore the feasibility of melting dissimilar and high melting temperature materials using fs lasers, but it also lays out a solid foundation for 3D printing of complex structure with designed compositions, microstructures and properties. This can greatly benefit the applications in automobile, aerospace and biomedical industries, by producing parts like nozzles, engines and miniaturized biomedical devices.

Novel Behavioral and Neural Evidences for Age-Related changes in Force complexity.

PubMed

Chen, Yi-Ching; Lin, Linda L; Hwang, Ing-Shiou

2018-02-17

This study investigated age-related changes in behavioral and neural complexity for a polyrhythmic movement, which appeared to be an exception to the loss of complexity hypothesis. Young (n = 15; age = 24.2 years) and older (15; 68.1 years) adults performed low-level force-tracking with isometric index abduction to couple a compound sinusoidal target. Multi-scale entropy (MSE) of tracking force and inter-spike interval (ISI) of motor unit (MU) in the first dorsal interosseus muscle were assessed. The MSE area of tracking force at shorter time scales of older adults was greater (more complex) than that of young adults, whereas an opposite trend (less complex for the elders) was noted at longer time scales. The MSE area of force fluctuations (the stochastic component of the tracking force) were generally smaller (less complex) for older adults. Along with greater mean and coefficient of ISI, the MSE area of the cumulative discharge rate of elders tended to be lower (less complex) than that of young adults. In conclusion, age-related complexity changes in polyrhythmic force-tracking depended on the time scale. The adaptive behavioral consequences could be multi-factorial origins of the age-related impairment in rate coding, increased discharge noises, and lower discharge complexity of pooled MUs.

Relationships between structural complexity, coral traits, and reef fish assemblages

NASA Astrophysics Data System (ADS)

Darling, Emily S.; Graham, Nicholas A. J.; Januchowski-Hartley, Fraser A.; Nash, Kirsty L.; Pratchett, Morgan S.; Wilson, Shaun K.

2017-06-01

With the ongoing loss of coral cover and the associated flattening of reef architecture, understanding the links between coral habitat and reef fishes is of critical importance. Here, we investigate whether considering coral traits and functional diversity provides new insights into the relationship between structural complexity and reef fish communities, and whether coral traits and community composition can predict structural complexity. Across 157 sites in Seychelles, Maldives, the Chagos Archipelago, and Australia's Great Barrier Reef, we find that structural complexity and reef zone are the strongest and most consistent predictors of reef fish abundance, biomass, species richness, and trophic structure. However, coral traits, diversity, and life histories provided additional predictive power for models of reef fish assemblages, and were key drivers of structural complexity. Our findings highlight that reef complexity relies on living corals—with different traits and life histories—continuing to build carbonate skeletons, and that these nuanced relationships between coral assemblages and habitat complexity can affect the structure of reef fish assemblages. Seascape-level estimates of structural complexity are rapid and cost effective with important implications for the structure and function of fish assemblages, and should be incorporated into monitoring programs.

Demographic and genetic viability of a medium-sized ground-dwelling mammal in a fire prone, rapidly urbanizing landscape.

PubMed

Ramalho, Cristina E; Ottewell, Kym M; Chambers, Brian K; Yates, Colin J; Wilson, Barbara A; Bencini, Roberta; Barrett, Geoff

2018-01-01

The rapid and large-scale urbanization of peri-urban areas poses major and complex challenges for wildlife conservation. We used population viability analysis (PVA) to evaluate the influence of urban encroachment, fire, and fauna crossing structures, with and without accounting for inbreeding effects, on the metapopulation viability of a medium-sized ground-dwelling mammal, the southern brown bandicoot (Isoodon obesulus), in the rapidly expanding city of Perth, Australia. We surveyed two metapopulations over one and a half years, and parameterized the PVA models using largely field-collected data. The models revealed that spatial isolation imposed by housing and road encroachment has major impacts on I. obesulus. Although the species is known to persist in small metapopulations at moderate levels of habitat fragmentation, the models indicate that these populations become highly vulnerable to demographic decline, genetic deterioration, and local extinction under increasing habitat connectivity loss. Isolated metapopulations were also predicted to be highly sensitive to fire, with large-scale fires having greater negative impacts on population abundance than small-scale ones. To reduce the risk of decline and local extirpation of I. obesulus and other small- to medium-sized ground-dwelling mammals in urbanizing, fire prone landscapes, we recommend that remnant vegetation and vegetated, structurally-complex corridors between habitat patches be retained. Well-designed road underpasses can be effective to connect habitat patches and reduce the probability of inbreeding and genetic differentiation; however, adjustment of fire management practices to limit the size of unplanned fires and ensure the retention of long unburnt vegetation will also be required to ensure persistence. Our study supports the evidence that in rapidly urbanizing landscapes, a pro-active conservation approach is required that manages species at the metapopulation level and that prioritizes metapopulations and habitat with greater long-term probability of persistence and conservation capacity, respectively. This strategy may help us prevent future declines and local extirpations, and currently relatively common species from becoming rare.

Demographic and genetic viability of a medium-sized ground-dwelling mammal in a fire prone, rapidly urbanizing landscape

PubMed Central

Ottewell, Kym M.; Chambers, Brian K.; Yates, Colin J.; Wilson, Barbara A.; Bencini, Roberta; Barrett, Geoff

2018-01-01

The rapid and large-scale urbanization of peri-urban areas poses major and complex challenges for wildlife conservation. We used population viability analysis (PVA) to evaluate the influence of urban encroachment, fire, and fauna crossing structures, with and without accounting for inbreeding effects, on the metapopulation viability of a medium-sized ground-dwelling mammal, the southern brown bandicoot (Isoodon obesulus), in the rapidly expanding city of Perth, Australia. We surveyed two metapopulations over one and a half years, and parameterized the PVA models using largely field-collected data. The models revealed that spatial isolation imposed by housing and road encroachment has major impacts on I. obesulus. Although the species is known to persist in small metapopulations at moderate levels of habitat fragmentation, the models indicate that these populations become highly vulnerable to demographic decline, genetic deterioration, and local extinction under increasing habitat connectivity loss. Isolated metapopulations were also predicted to be highly sensitive to fire, with large-scale fires having greater negative impacts on population abundance than small-scale ones. To reduce the risk of decline and local extirpation of I. obesulus and other small- to medium-sized ground-dwelling mammals in urbanizing, fire prone landscapes, we recommend that remnant vegetation and vegetated, structurally-complex corridors between habitat patches be retained. Well-designed road underpasses can be effective to connect habitat patches and reduce the probability of inbreeding and genetic differentiation; however, adjustment of fire management practices to limit the size of unplanned fires and ensure the retention of long unburnt vegetation will also be required to ensure persistence. Our study supports the evidence that in rapidly urbanizing landscapes, a pro-active conservation approach is required that manages species at the metapopulation level and that prioritizes metapopulations and habitat with greater long-term probability of persistence and conservation capacity, respectively. This strategy may help us prevent future declines and local extirpations, and currently relatively common species from becoming rare. PMID:29444118

Similarity, Not Complexity, Determines Visual Working Memory Performance

ERIC Educational Resources Information Center

Jackson, Margaret C.; Linden, David E. J.; Roberts, Mark V.; Kriegeskorte, Nikolaus; Haenschel, Corinna

2015-01-01

A number of studies have shown that visual working memory (WM) is poorer for complex versus simple items, traditionally accounted for by higher information load placing greater demands on encoding and storage capacity limits. Other research suggests that it may not be complexity that determines WM performance per se, but rather increased…

Task Complexity, Language-Related Episodes, and Production of L2 Spanish Vowels

ERIC Educational Resources Information Center

Solon, Megan; Long, Avizia Y.; Gurzynski-Weiss, Laura

2017-01-01

This study tests the theoretical predictions regarding effects of increasing task complexity (Robinson, 2001a, 2001b, 2007, 2010; Robinson & Gilabert, 2007) for second language (L2) pronunciation. Specifically, we examine whether more complex tasks (a) lead to greater incidence of pronunciation-focused language-related episodes (LREs) and (b)…

High Temperature Transfer Molding Resins: Status of PETI-298 and PETI-330

NASA Technical Reports Server (NTRS)

Connell, John W.; Smith, Joseph G., Jr.; Hergenrother, Paul M.; Criss, Jim M.

2003-01-01

Two phenylethynyl terminated oligomers designated PETI-298 and PETI-330 were developed at the NASA Langley Research Center and have emerged as leading candidates for composite applications requiring high temperature performance (i.e. greater than or equal to 288 C for 1000 hours) combined with the ability to be readily processed into composites without the use of an autoclave or complex/lengthy cure or post-cure cycle. These high performance/high temperature composites are potentially useful on advanced aerospace vehicles in structural applications and as aircraft engine components such as inlet frames and compressor vanes. The number designation (i.e. 298, 330) refers to the glass transition temperature in degrees Celsius as determined on neat resin cured for 1 hour at 371 C. The resins are processable by non-autoclave techniques such as resin transfer molding (RTM), vacuum assisted RTM (VARTM) and resin infusion (RI). Both resins exhibit low complex melt viscosities (0.1-10 poise) at 280 C and are stable for greater than or equal to 2 hours at this temperature. Typically, the resins are melted, de-gassed and infused or injected at 280 C and subsequently cured at 371 C for 1-2 hours. Virtually no volatiles are evolved during the cure process. The resin synthesis is straightforward and has been scaled-up to 25 kg batches. The chemistry of PETI-298 and PETI-330 and the RTM AS-4 and T-650 carbon fabric laminate properties, and those of BMI-5270 for comparison, are presented.

Concept Maps for Improved Science Reasoning and Writing: Complexity Isn't Everything.

PubMed

Dowd, Jason E; Duncan, Tanya; Reynolds, Julie A

2015-01-01

A pervasive notion in the literature is that complex concept maps reflect greater knowledge and/or more expert-like thinking than less complex concept maps. We show that concept maps used to structure scientific writing and clarify scientific reasoning do not adhere to this notion. In an undergraduate course for thesis writers, students use concept maps instead of traditional outlines to define the boundaries and scope of their research and to construct an argument for the significance of their research. Students generate maps at the beginning of the semester, revise after peer review, and revise once more at the end of the semester. Although some students revised their maps to make them more complex, a significant proportion of students simplified their maps. We found no correlation between increased complexity and improved scientific reasoning and writing skills, suggesting that sometimes students simplify their understanding as they develop more expert-like thinking. These results suggest that concept maps, when used as an intervention, can meet the varying needs of a diverse population of student writers. © 2015 J. E. Dowd et al. CBE—Life Sciences Education © 2015 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Two-photon luminescence from polar bis-terpyridyl-stilbene derivatives of Ir(III) and Ru(II).

PubMed

Natrajan, Louise S; Toulmin, Anita; Chew, Alex; Magennis, Steven W

2010-12-07

Four structurally related iridium(III) and ruthenium(II) complexes bearing two polar terpyridyl-stilbene derived chromophores 4-(4-{2-[4-(methoxy)phenyl]ethenyl}phenyl)-2,2'-6',2''-terpyridine (ttpyeneanisole) and 4-(4-{2-[phenyl]ethenyl}phenyl)-2,2'-6',2''-terpyridine (tpystilbene) have been synthesised and characterised in the solid state and in solution. In the solid state, the dihedral angle subtending the pyridyl and tolyl groups of 27.1° in the Ir(III) complex [Ir(ttpyeneanisole)(2)]·3PF(6) is more acute than in the Ru(II) derivative [Ru(tpystilbene)(2)]·2PF(6) (35.5°), indicating the presence of a greater degree of π-delocalisation across the terpyridine unit in the former compound. Their luminescence properties in fluid solution have been investigated following both resonant and non-resonant excitation. We have shown that each of the complexes undergoes two-photon excitation when excited in the near infrared (740 to 820 nm), with two-photon absorption cross sections in the range 11-67 × 10(-50) cm(4) s photon(-1). The larger cross sections for the Ir(III) complexes reflect the differences observed in the solid state. This work therefore demonstrates that such complexes are promising as luminescent markers for 3D imaging and illustrates that simple functionalisation of the chromophores and the choice of metal can lead to marked enhancements in the two-photon cross sections (σ(2)) compared to those of simpler heteroleptic polypyridyl based derivatives.

Kinematic analysis of mélange fabrics: examples and applications from the McHugh Complex, Kenai Peninsula, Alaska

NASA Astrophysics Data System (ADS)

Kusky, Timothy M.; Bradley, Dwight C.

1999-12-01

Permian to Cretaceous mélange of the McHugh Complex on the Kenai Peninsula, south-central Alaska includes blocks and belts of graywacke, argillite, limestone, chert, basalt, gabbro, and ultramafic rocks, intruded by a variety of igneous rocks. An oceanic plate stratigraphy is repeated hundreds of times across the map area, but most structures at the outcrop scale extend lithological layering. Strong rheological units occur as blocks within a matrix that flowed around the competent blocks during deformation, forming broken formation and mélange. Deformation was noncoaxial, and disruption of primary layering was a consequence of general strain driven by plate convergence in a relatively narrow zone between the overriding accretionary wedge and the downgoing, generally thinly sedimented oceanic plate. Soft-sediment deformation processes do not appear to have played a major role in the formation of the mélange. A model for deformation at the toe of the wedge is proposed in which layers oriented at low angles to σ1 are contracted in both the brittle and ductile regimes, layers at 30-45° to σ1 are extended in the brittle regime and contracted in the ductile regime, and layers at angles greater than 45° to σ1 are extended in both the brittle and ductile regimes. Imbrication in thrust duplexes occurs at deeper levels within the wedge. Many structures within mélange of the McHugh Complex are asymmetric and record kinematic information consistent with the inferred structural setting in an accretionary wedge. A displacement field for the McHugh Complex on the lower Kenai Peninsula includes three belts: an inboard belt of Late Triassic rocks records west-to-east-directed slip of hanging walls, a central belt of predominantly Early Jurassic rocks records north-south directed displacements, and Early Cretaceous rocks in an outboard belt preserve southwest-northeast directed slip vectors. Although precise ages of accretion are unknown, slip directions are compatible with inferred plate motions during the general time frame of accretion of the McHugh Complex. The slip vectors are interpreted to preserve the convergence directions between the overriding and underriding plates, which became more oblique with time. They are not considered indicative of strain partitioning into belts of orogen-parallel and orogen-perpendicular displacements, because the kinematic data are derived from the earliest preserved structures, whereas fabrics related to strain partitioning would be expected to be superimposed on earlier accretion-related fabrics.

Vocal communication in a complex multi-level society: constrained acoustic structure and flexible call usage in Guinea baboons.

PubMed

Maciej, Peter; Ndao, Ibrahima; Hammerschmidt, Kurt; Fischer, Julia

2013-09-23

To understand the evolution of acoustic communication in animals, it is important to distinguish between the structure and the usage of vocal signals, since both aspects are subject to different constraints. In terrestrial mammals, the structure of calls is largely innate, while individuals have a greater ability to actively initiate or withhold calls. In closely related taxa, one would therefore predict a higher flexibility in call usage compared to call structure. In the present study, we investigated the vocal repertoire of free living Guinea baboons (Papio papio) and examined the structure and usage of the animals' vocal signals. Guinea baboons live in a complex multi-level social organization and exhibit a largely tolerant and affiliative social style, contrary to most other baboon taxa. To classify the vocal repertoire of male and female Guinea baboons, cluster analyses were used and focal observations were conducted to assess the usage of vocal signals in the particular contexts. In general, the vocal repertoire of Guinea baboons largely corresponded to the vocal repertoire other baboon taxa. The usage of calls, however, differed considerably from other baboon taxa and corresponded with the specific characteristics of the Guinea baboons' social behaviour. While Guinea baboons showed a diminished usage of contest and display vocalizations (a common pattern observed in chacma baboons), they frequently used vocal signals during affiliative and greeting interactions. Our study shows that the call structure of primates is largely unaffected by the species' social system (including grouping patterns and social interactions), while the usage of calls can be more flexibly adjusted, reflecting the quality of social interactions of the individuals. Our results support the view that the primary function of social signals is to regulate social interactions, and therefore the degree of competition and cooperation may be more important to explain variation in call usage than grouping patterns or group size.

Vocal communication in a complex multi-level society: constrained acoustic structure and flexible call usage in Guinea baboons

PubMed Central

2013-01-01

Background To understand the evolution of acoustic communication in animals, it is important to distinguish between the structure and the usage of vocal signals, since both aspects are subject to different constraints. In terrestrial mammals, the structure of calls is largely innate, while individuals have a greater ability to actively initiate or withhold calls. In closely related taxa, one would therefore predict a higher flexibility in call usage compared to call structure. In the present study, we investigated the vocal repertoire of free living Guinea baboons (Papio papio) and examined the structure and usage of the animals’ vocal signals. Guinea baboons live in a complex multi-level social organization and exhibit a largely tolerant and affiliative social style, contrary to most other baboon taxa. To classify the vocal repertoire of male and female Guinea baboons, cluster analyses were used and focal observations were conducted to assess the usage of vocal signals in the particular contexts. Results In general, the vocal repertoire of Guinea baboons largely corresponded to the vocal repertoire other baboon taxa. The usage of calls, however, differed considerably from other baboon taxa and corresponded with the specific characteristics of the Guinea baboons’ social behaviour. While Guinea baboons showed a diminished usage of contest and display vocalizations (a common pattern observed in chacma baboons), they frequently used vocal signals during affiliative and greeting interactions. Conclusions Our study shows that the call structure of primates is largely unaffected by the species’ social system (including grouping patterns and social interactions), while the usage of calls can be more flexibly adjusted, reflecting the quality of social interactions of the individuals. Our results support the view that the primary function of social signals is to regulate social interactions, and therefore the degree of competition and cooperation may be more important to explain variation in call usage than grouping patterns or group size. PMID:24059742

Role of organic cation/carnitine transporter 1 in uptake of phenformin and inhibitory effect on complex I respiration in mitochondria.

PubMed

Shitara, Yoshihisa; Nakamichi, Noritaka; Norioka, Misaki; Shima, Hiroyo; Kato, Yukio; Horie, Toshiharu

2013-03-01

Phenformin causes lactic acidosis in clinical situations due to inhibition of mitochondrial respiratory chain complex I. It is reportedly taken up by hepatocytes and exhibits mitochondrial toxicity in the liver. In this study, uptake of phenformin and [(14)C]tetraethylammonium (TEA) and complex I inhibition by phenformin were examined in isolated liver and heart mitochondria. Uptake of phenformin into isolated rat liver mitochondria was higher than that into heart mitochondria. It was inhibited by several cat ionic compounds, which suggests the involvement of multispecific transport system(s). Similar characteristics were also observed for uptake of TEA; however, uptake of phenformin into mitochondria of organic cation/carnitine transporter 1 (OCTN1) knockout mice was lower than that in wild-type mice, whereas uptake of TEA was comparable between the two strains, suggesting the involvement of distinct transport mechanisms for these two cations in mitochondria. Inhibition by phenformin of oxygen consumption via complex I respiration in isolated rat liver mitochondria was greater than that in heart mitochondria, whereas inhibitory effect of phenformin on complex I respiration was similar in inside-out structured submitochondrial particles prepared from rat livers and hearts. Lactic acidosis provoked by iv infusion of phenformin was weaker in octn1(-/-) mice than that in wild-type mice. These observations suggest that uptake of phenformin into liver mitochondria is at least partly mediated by OCTN1 and functionally relevant to its inhibition potential of complex I respiration. This study was, thus, the first to demonstrate OCTN1-mediated mitochondrial transport and toxicity of biguanide in vivo in rodents.

Comparative cephalopod shell strength and the role of septum morphology on stress distribution

PubMed Central

Zachow, Stefan; Hoffmann, René

2016-01-01

The evolution of complexly folded septa in ammonoids has long been a controversial topic. Explanations of the function of these folded septa can be divided into physiological and mechanical hypotheses with the mechanical functions tending to find widespread support. The complexity of the cephalopod shell has made it difficult to directly test the mechanical properties of these structures without oversimplification of the septal morphology or extraction of a small sub-domain. However, the power of modern finite element analysis now permits direct testing of mechanical hypothesis on complete, empirical models of the shells taken from computed tomographic data. Here we compare, for the first time using empirical models, the capability of the shells of extant Nautilus pompilius, Spirula spirula, and the extinct ammonite Cadoceras sp. to withstand hydrostatic pressure and point loads. Results show hydrostatic pressure imparts highest stress on the final septum with the rest of the shell showing minimal compression. S. spirula shows the lowest stress under hydrostatic pressure while N. pompilius shows the highest stress. Cadoceras sp. shows the development of high stress along the attachment of the septal saddles with the shell wall. Stress due to point loads decreases when the point force is directed along the suture as opposed to the unsupported chamber wall. Cadoceras sp. shows the greatest decrease in stress between the point loads compared to all other models. Greater amplitude of septal flutes corresponds with greater stress due to hydrostatic pressure; however, greater amplitude decreases the stress magnitude of point loads directed along the suture. In our models, sutural complexity does not predict greater resistance to hydrostatic pressure but it does seem to increase resistance to point loads, such as would be from predators. This result permits discussion of palaeoecological reconstructions on the basis of septal morphology. We further suggest that the ratio used to characterize septal morphology in the septal strength index and in calculations of tensile strength of nacre are likely insufficient. A better understanding of the material properties of cephalopod nacre may allow the estimation of maximum depth limits of shelled cephalopods through finite element analysis. PMID:27672501

Energy absorption capabilities of complex thin walled structures

NASA Astrophysics Data System (ADS)

Tarlochan, F.; AlKhatib, Sami

2017-10-01

Thin walled structures have been used in the area of energy absorption during an event of a crash. A lot of work has been done on tubular structures. Due to limitation of manufacturing process, complex geometries were dismissed as potential solutions. With the advancement in metal additive manufacturing, complex geometries can be realized. As a motivation, the objective of this study is to investigate computationally the crash performance of complex tubular structures. Five designs were considered. In was found that complex geometries have better crashworthiness performance than standard tubular structures used currently.

From the Director: The Joy of Science, the Courage of Research

MedlinePlus

... Dr. Zerhouni , one that combines an appreciation of biological complexity with the fearless search for scientific knowledge. ... techniques for greater understanding of the complexity of biological systems. The one thing that has driven my ...

Driving force analysis of proton tunnelling across a reactivity series for an enzyme-substrate complex.

PubMed

Hothi, Parvinder; Hay, Sam; Roujeinikova, Anna; Sutcliffe, Michael J; Lee, Michael; Leys, David; Cullis, Paul M; Scrutton, Nigel S

2008-11-24

Quantitative structure-activity relationships are widely used to probe C-H bond breakage by quinoprotein enzymes. However, we showed recently that p-substituted benzylamines are poor reactivity probes for the quinoprotein aromatic amine dehydrogenase (AADH) because of a requirement for structural change in the enzyme-substrate complex prior to C-H bond breakage. This rearrangement is partially rate limiting, which leads to deflated kinetic isotope effects for p-substituted benzylamines. Here we report reactivity (driving force) studies of AADH with p-substituted phenylethylamines for which the kinetic isotope effect (approximately 16) accompanying C-H/C-(2)H bond breakage is elevated above the semi-classical limit. We show bond breakage occurs by quantum tunnelling and that within the context of the environmentally coupled framework for H-tunnelling the presence of the p-substituent places greater demand on the apparent need for fast promoting motions. The crystal structure of AADH soaked with phenylethylamine or methoxyphenylethylamine indicates that the structural change identified with p-substituted benzylamines should not limit the reaction with p-substituted phenylethylamines. This is consistent with the elevated kinetic isotope effects measured with p-substituted phenylethylamines. We find a good correlation in the rate constant for proton transfer with bond dissociation energy for the reactive C-H bond, consistent with a rate that is limited by a Marcus-like tunnelling mechanism. As the driving force becomes larger, the rate of proton transfer increases while the Marcus activation energy becomes smaller. This is the first experimental report of the driving force perturbation of H-tunnelling in enzymes using a series of related substrates. Our study provides further support for proton tunnelling in AADH.

Second harmonic generation imaging of skeletal muscle tissue and myofibrils

NASA Astrophysics Data System (ADS)

Campagnola, Paul J.; Mohler, William H.; Plotnikov, Sergey; Millard, Andrew C.

2006-02-01

Second Harmonic Generation (SHG) imaging microscopy is used to examine the morphology and structural properties of intact muscle tissue. Using biochemical and optical analysis, we characterize the molecular structure underlying SHG from the complex muscle sarcomere. We find that SHG from isolated myofibrils is abolished by extraction of myosin, but is unaffected by removal or addition of actin filaments. We thus determined that the SHG emission arises from domains of the sarcomere containing thick filaments. By fitting the SHG polarization anisotropy to theoretical response curves, we find an orientation for the harmonophore that corresponds well to the pitch angle of the myosin rod α-helix with respect to the thick filament axis. Taken together, these data indicate that myosin rod domains are the key structures giving rise to SHG from striated muscle. Using SHG imaging microscopy, we have also examined the effect of optical clearing with glycerol to achieve greater penetration into specimens of skeletal muscle tissue. We find that treatment with 50% glycerol results in a 2.5 fold increase in achievable SHG imaging depth. Fast Fourier Transform (FFT) analysis shows quantitatively that the periodicity of the sarcomere structure is unaltered by the clearing process. Also, comparison of the SHG angular polarization dependence shows no change in the supramolecular organization of acto-myosin complexes. We suggest that the primary mechanism of optical clearing in muscle with glycerol treatment results from the reduction of cytoplasmic protein concentration and concomitant decrease in the secondary inner filter effect on the SHG signal. The pronounced lack of dependence of glycerol concentration on the imaging depth indicates that refractive index matching plays only a minor role in the optical clearing of muscle.

Flow Structure and Force Variation with Aspect Ratio for a Two-Degree-of-Freedom Flapping Wing

NASA Astrophysics Data System (ADS)

Burge, Matthew; Favale, James; Ringuette, Matthew

2014-11-01

We investigate experimentally the effect of aspect ratio (AR) on the flow structure and forces of a two-degree-of-freedom flapping wing. Flapping wings are known to produce complex and unsteady vortex loop structures, and the objective is to characterize their variation with AR and how this influences the lift force. Previous results on rotating wings demonstrated that changes in AR significantly affect the three-dimensional flow structure and lift coefficient. This is primarily due to the relatively greater influence of the tip vortex for lower AR. At Reynolds number of order O(103) we test wings of AR = 2-4, values typically found in nature, with simplified planform shapes. The lift force is measured using a submersible transducer at the base of the wing in a glycerin-water mixture. The qualitative, three-dimensional vortex loop structure for different ARs is obtained using multi-color dye flow visualization. Guided by this, quantitative three-component flow information, namely vorticity, the Q-criterion, and circulation, is acquired from stereoscopic particle image velocimetry in key planes. Of interest is how these parameters and the vortex loop topology vary with AR, and their connection to features in the unsteady force signal. This work is supported by the National Science Foundation, Award Number 1336548, supervised by Dr. Dimitrios Papavassiliou.

A soft gamma-ray concentrator using thin-film multilayer structures

NASA Astrophysics Data System (ADS)

Bloser, Peter F.; Aliotta, Paul H.; Echt, Olof; Krzanowski, James E.; Legere, Jason S.; McConnell, Mark L.; Shirazi, Farzane; Tsavalas, John G.; Wong, Emily N.; Kippen, R. Marc

2015-09-01

We have begun to investigate the use of thin-film, multilayer structures to form optics capable of concentrating soft gamma rays with energies greater than 100 keV, beyond the reach of current grazing-incidence hard X-ray mirrors. Alternating layers of low- and high-density materials (e.g., polymers and metals) will channel soft gamma-ray photons via total external reflection. A suitable arrangement of bent structures will then concentrate the incident radiation to a point. Gamma-ray optics made in this way offer the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and opening the field up to balloon-borne instruments. Building on initial investigations at Los Alamos National Laboratory, we are investigating whether it is possible to grow such flexible multi-layer structures with the required thicknesses and smoothness using magnetron sputter and pulsed laser deposition techniques. We present the initial results of tests aimed at fabricating such structures by combining magnetron sputtering with either spin coating or pulsed laser deposition, and demonstrating gamma-ray channeling of 122 keV photons in the laboratory. If successful, this technology offers the potential for transformational increases in sensitivity while dramatically improving the system-level performance of future high-energy astronomy missions through reduced mass and complexity.

Kinetic and structural characterization of amyloid-β peptide hydrolysis by human angiotensin-1-converting enzyme.

PubMed

Larmuth, Kate M; Masuyer, Geoffrey; Douglas, Ross G; Schwager, Sylva L; Acharya, K Ravi; Sturrock, Edward D

2016-03-01

Angiotensin-1-converting enzyme (ACE), a zinc metallopeptidase, consists of two homologous catalytic domains (N and C) with different substrate specificities. Here we report kinetic parameters of five different forms of human ACE with various amyloid beta (Aβ) substrates together with high resolution crystal structures of the N-domain in complex with Aβ fragments. For the physiological Aβ(1-16) peptide, a novel ACE cleavage site was found at His14-Gln15. Furthermore, Aβ(1-16) was preferentially cleaved by the individual N-domain; however, the presence of an inactive C-domain in full-length somatic ACE (sACE) greatly reduced enzyme activity and affected apparent selectivity. Two fluorogenic substrates, Aβ(4-10)Q and Aβ(4-10)Y, underwent endoproteolytic cleavage at the Asp7-Ser8 bond with all ACE constructs showing greater catalytic efficiency for Aβ(4-10)Y. Surprisingly, in contrast to Aβ(1-16) and Aβ(4-10)Q, sACE showed positive domain cooperativity and the double C-domain (CC-sACE) construct no cooperativity towards Aβ(4-10)Y. The structures of the Aβ peptide-ACE complexes revealed a common mode of peptide binding for both domains which principally targets the C-terminal P2' position to the S2' pocket and recognizes the main chain of the P1' peptide. It is likely that N-domain selectivity for the amyloid peptide is conferred through the N-domain specific S2' residue Thr358. Additionally, the N-domain can accommodate larger substrates through movement of the N-terminal helices, as suggested by the disorder of the hinge region in the crystal structures. Our findings are important for the design of domain selective inhibitors as the differences in domain selectivity are more pronounced with the truncated domains compared to the more physiological full-length forms. The atomic coordinates and structure factors for N-domain ACE with Aβ peptides 4-10 (5AM8), 10-16 (5AM9), 1-16 (5AMA), 35-42 (5AMB) and (4-10)Y (5AMC) complexes have been deposited in the Protein Data Bank, Research Collaboratory for Structural Bioinformatics, Rutgers University, New Brunswick, NJ, USA (http://www.rcsb.org/). © 2016 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.

Lipid chain geometry of C14 glycerol-based lipids: effect on lipoplex structure and transfection.

PubMed

Kudsiova, Laila; Ho, Jimmy; Fridrich, Barbara; Harvey, Richard; Keppler, Melanie; Ng, Tony; Hart, Stephen L; Tabor, Alethea B; Hailes, Helen C; Lawrence, M Jayne

2011-02-01

The effects have been determined of a systematic alteration of the alkyl chain geometry of a C14 analogue of DOTMA on the detailed molecular architecture of the resulting cationic vesicles formed both in the absence and presence of 50 mol% DOPE, and of the lipoplexes prepared from these vesicles using either calf thymus or plasmid DNA. The C14 DOTMA analogues studied involved cis- or trans-double bonds at positions Δ9 or Δ11, and a compound (ALK) featuring an alkyne at position C9. For all of these analogues, examination by light scattering and neutron scattering, zeta potential measurement, and negative staining electron microscopy showed that there were no significant differences in the structures or charges of the vesicles or of the resulting lipoplexes, regardless of the nature of the DNA incorporated. Differences were observed, however, between the complexes formed by the various lipids when examining the extent of complexation and release by gel electrophoresis, where the E-lipids appeared to complex the DNA more efficiently than all other lipids tested. Moreover, the lipoplexes prepared from the E-lipids were the most effective in transfection of MDA-MB-231 breast cancer cells. As indicated through confocal microscopy studies, the E-lipids also showed a higher internalisation capacity and a more diffuse cellular distribution, possibly indicating a greater degree of endosomal escape and/or nuclear import. These observations suggest that the extent of complexation is the most important factor in determining the transfection efficiency of the complexes tested. At present it is unclear why the E-lipids were more effective at complexing DNA, although it is thought that the effective area per molecule occupied by the cationic lipid and DOPE head groups, and therefore the density of positive charges on the surface of the bilayer most closely matches the negative charge density of the DNA molecule. From a consideration of the geometry of the cationic lipids it is anticipated that the head groups of the E-lipids would occupy a smaller area per molecule than the ALK or Z-lipids.

Saturation kinetics in phenolic O-H bond oxidation by a mononuclear Mn(III)-OH complex derived from dioxygen.

PubMed

Wijeratne, Gayan B; Corzine, Briana; Day, Victor W; Jackson, Timothy A

2014-07-21

The mononuclear hydroxomanganese(III) complex, [Mn(III)(OH)(dpaq)](+), which is supported by the amide-containing N5 ligand dpaq (dpaq = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-yl-acetamidate) was generated by treatment of the manganese(II) species, [Mn(II)(dpaq)](OTf), with dioxygen in acetonitrile solution at 25 °C. This oxygenation reaction proceeds with essentially quantitative yield (greater than 98% isolated yield) and represents a rare example of an O2-mediated oxidation of a manganese(II) complex to generate a single product. The X-ray diffraction structure of [Mn(III)(OH)(dpaq)](+) reveals a short Mn-OH distance of 1.806(13) Å, with the hydroxo moiety trans to the amide function of the dpaq ligand. No shielding of the hydroxo group is observed in the solid-state structure. Nonetheless, [Mn(III)(OH)(dpaq)](+) is remarkably stable, decreasing in concentration by only 10% when stored in MeCN at 25 °C for 1 week. The [Mn(III)(OH)(dpaq)](+) complex participates in proton-coupled electron transfer reactions with substrates with relatively weak O-H and C-H bonds. For example, [Mn(III)(OH)(dpaq)](+) oxidizes TEMPOH (TEMPOH = 2,2'-6,6'-tetramethylpiperidine-1-ol), which has a bond dissociation free energy (BDFE) of 66.5 kcal/mol, in MeCN at 25 °C. The hydrogen/deuterium kinetic isotope effect of 1.8 observed for this reaction implies a concerted proton-electron transfer pathway. The [Mn(III)(OH)(dpaq)](+) complex also oxidizes xanthene (C-H BDFE of 73.3 kcal/mol in dimethylsulfoxide) and phenols, such as 2,4,6-tri-t-butylphenol, with BDFEs of less than 79 kcal/mol. Saturation kinetics were observed for phenol oxidation, implying an initial equilibrium prior to the rate-determining step. On the basis of a collective body of evidence, the equilibrium step is attributed to the formation of a hydrogen-bonding complex between [Mn(III)(OH)(dpaq)](+) and the phenol substrates.

New Age of 3D Geological Modelling or Complexity is not an Issue Anymore

NASA Astrophysics Data System (ADS)

Mitrofanov, Aleksandr

2017-04-01

Geological model has a significant value in almost all types of researches related to regional mapping, geodynamics and especially to structural and resource geology of mineral deposits. Well-developed geological model must take into account all vital features of modelling object without over-simplification and also should adequately represent the interpretation of the geologist. In recent years with the gradual exhaustion deposits with relatively simple morphology geologists from all over the world are faced with the necessity of building the representative models for more and more structurally complex objects. Meanwhile, the amount of tools used for that has not significantly changed in the last two-three decades. The most widespread method of wireframe geological modelling now was developed in 1990s and is fully based on engineering design set of instruments (so-called CAD). Strings and polygons representing the section-based interpretation are being used as an intermediate step in the process of wireframes generation. Despite of significant time required for this type of modelling, it still can provide sufficient results for simple and medium-complexity geological objects. However, with the increasing complexity more and more vital features of the deposit are being sacrificed because of fundamental inability (or much greater time required for modelling) of CAD-based explicit techniques to develop the wireframes of the appropriate complexity. At the same time alternative technology which is not based on sectional approach and which uses the fundamentally different mathematical algorithms is being actively developed in the variety of other disciplines: medicine, advanced industrial design, game and cinema industry. In the recent years this implicit technology started to being developed for geological modelling purpose and nowadays it is represented by very powerful set of tools that has been integrated in almost all major commercial software packages. Implicit modelling allows to develop geological models that really correspond with complicated geological reality. Models can include fault blocking, complex structural trends and folding; can be based on excessive input dataset (like lots of drilling on the mining stage) or, on the other hand, on a quite few drillholes intersections with significant input from geological interpretation of the deposit. In any case implicit modelling, if is used correctly, allows to incorporate the whole batch of geological data and relatively quickly get the easily adjustable, flexible and robust geological wireframes that can be used as a reliable foundation on the following stages of geological investigations. In SRK practice nowadays almost all the wireframe models used for structural and resource geology are developed with implicit modelling tools which significantly increased the speed and quality of geological modelling.

Developmental Sex Differences in the Relation of Neuroanatomical Connectivity to Intelligence

ERIC Educational Resources Information Center

Schmithorst, Vincent J.

2009-01-01

Recent neuroimaging research has shown sex-related differences in the relationship between brain structure and cognitive function. Anatomical studies have shown a greater reliance for cognitive function on white matter structure in adult females, and a greater reliance on gray matter structure in adult males. Functional neuroimaging studies have…

Decoupling local mechanics from large-scale structure in modular metamaterials.

PubMed

Yang, Nan; Silverberg, Jesse L

2017-04-04

A defining feature of mechanical metamaterials is that their properties are determined by the organization of internal structure instead of the raw fabrication materials. This shift of attention to engineering internal degrees of freedom has coaxed relatively simple materials into exhibiting a wide range of remarkable mechanical properties. For practical applications to be realized, however, this nascent understanding of metamaterial design must be translated into a capacity for engineering large-scale structures with prescribed mechanical functionality. Thus, the challenge is to systematically map desired functionality of large-scale structures backward into a design scheme while using finite parameter domains. Such "inverse design" is often complicated by the deep coupling between large-scale structure and local mechanical function, which limits the available design space. Here, we introduce a design strategy for constructing 1D, 2D, and 3D mechanical metamaterials inspired by modular origami and kirigami. Our approach is to assemble a number of modules into a voxelized large-scale structure, where the module's design has a greater number of mechanical design parameters than the number of constraints imposed by bulk assembly. This inequality allows each voxel in the bulk structure to be uniquely assigned mechanical properties independent from its ability to connect and deform with its neighbors. In studying specific examples of large-scale metamaterial structures we show that a decoupling of global structure from local mechanical function allows for a variety of mechanically and topologically complex designs.

Decoupling local mechanics from large-scale structure in modular metamaterials

NASA Astrophysics Data System (ADS)

Yang, Nan; Silverberg, Jesse L.

2017-04-01

A defining feature of mechanical metamaterials is that their properties are determined by the organization of internal structure instead of the raw fabrication materials. This shift of attention to engineering internal degrees of freedom has coaxed relatively simple materials into exhibiting a wide range of remarkable mechanical properties. For practical applications to be realized, however, this nascent understanding of metamaterial design must be translated into a capacity for engineering large-scale structures with prescribed mechanical functionality. Thus, the challenge is to systematically map desired functionality of large-scale structures backward into a design scheme while using finite parameter domains. Such “inverse design” is often complicated by the deep coupling between large-scale structure and local mechanical function, which limits the available design space. Here, we introduce a design strategy for constructing 1D, 2D, and 3D mechanical metamaterials inspired by modular origami and kirigami. Our approach is to assemble a number of modules into a voxelized large-scale structure, where the module’s design has a greater number of mechanical design parameters than the number of constraints imposed by bulk assembly. This inequality allows each voxel in the bulk structure to be uniquely assigned mechanical properties independent from its ability to connect and deform with its neighbors. In studying specific examples of large-scale metamaterial structures we show that a decoupling of global structure from local mechanical function allows for a variety of mechanically and topologically complex designs.

Facet-Dependent Deposition of Highly Strained Alloyed Shells on Intermetallic Nanoparticles for Enhanced Electrocatalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chenyu; Sang, Xiahan; Gamler, Jocelyn T. L.

Compressive surface strains can enhance the performance of platinum-based core@shell electrocatalysts for the oxygen reduction reaction (ORR). Bimetallic core@shell nanoparticles (NPs) are widely studied nanocatalysts but often have limited lattice mismatch and surface compositions; investigations of core@shell NPs with greater compositional complexity and lattice misfit are in their infancy. Here, a new class of multimetallic NPs composed of intermetallic cores and random alloy shells is reported. Specifically, face-centered cubic (fcc) Pt- Cu random alloy shells were deposited non-epitaxially on PdCu B2 intermetallic seeds, giving rise to faceted core@shell NPs with highly strained surfaces. In fact, high resolution transmission electron microscopymore » (HRTEM) revealed orientation-dependent surface strains, where the compressive strains were minimal on Pt-Cu {111} facets but greater on {200} facets. These core@shell NPs provide higher specific and mass activities for the ORR when compared to conventional Pt-Cu NPs. Moreover, these intermetallic@random alloy NPs displayed high endurance, undergoing 10,000 cycles with only a slight decay in activity and no apparent structural changes.« less

Algological and Mycological Characterization of Soils under Pine and Birch Forests in the Pasvik Reserve

NASA Astrophysics Data System (ADS)

Korneikova, M. V.; Redkina, V. V.; Shalygina, R. R.

2018-02-01

The structure of algological and mycological complexes in Al-Fe-humus podzols (Albic Podzols) under pine and birch forests of the Pasvik Reserve is characterized. The number of micromycetes is higher in more acid soils of the pine forest, while the species diversity is greater under the birch forest. The genus Penicillium includes the largest number of species. The greatest abundance and occurrence frequency are typical for Penicillium spinulosum, P. glabrum, and Trichoderma viride in pine forest and for Umbelopsis isabellina, Mucor sp., Mortierella alpina, P. glabrum, Aspergillus ustus, Trichoderma viride, and T. koningii in birch forest. Cyanobacteria-algal cenoses of the investigated soils are predominated by green algae. Soils under birch forest are distinguished by a greater diversity of algal groups due to the presence of diatoms and xanthophytes. Species of frequent occurrence are represented by Pseudococcomyxa simplex and Parietochloris alveolaris in soils of the pine forest and by Tetracystis cf. aplanospora, Halochlorella rubescens, Pseudococcomyxa simplex, Fottea stichococcoides, Klebsormidium flaccidum, Hantzschia amphioxys, Microcoleus vaginatus, and Aphanocapsa sp. in soils under birch forest

Facet-Dependent Deposition of Highly Strained Alloyed Shells on Intermetallic Nanoparticles for Enhanced Electrocatalysis

DOE PAGES

Wang, Chenyu; Sang, Xiahan; Gamler, Jocelyn T. L.; ...

2017-08-25

Compressive surface strains can enhance the performance of platinum-based core@shell electrocatalysts for the oxygen reduction reaction (ORR). Bimetallic core@shell nanoparticles (NPs) are widely studied nanocatalysts but often have limited lattice mismatch and surface compositions; investigations of core@shell NPs with greater compositional complexity and lattice misfit are in their infancy. Here, a new class of multimetallic NPs composed of intermetallic cores and random alloy shells is reported. Specifically, face-centered cubic (fcc) Pt- Cu random alloy shells were deposited non-epitaxially on PdCu B2 intermetallic seeds, giving rise to faceted core@shell NPs with highly strained surfaces. In fact, high resolution transmission electron microscopymore » (HRTEM) revealed orientation-dependent surface strains, where the compressive strains were minimal on Pt-Cu {111} facets but greater on {200} facets. These core@shell NPs provide higher specific and mass activities for the ORR when compared to conventional Pt-Cu NPs. Moreover, these intermetallic@random alloy NPs displayed high endurance, undergoing 10,000 cycles with only a slight decay in activity and no apparent structural changes.« less

Sport type and interpersonal and intrapersonal predictors of body dissatisfaction in high school female sport participants.

PubMed

Karr, Trisha M; Davidson, Denise; Bryant, Fred B; Balague, Gloria; Bohnert, Amy M

2013-03-01

Through multiple group structural equation modeling analyses, path models were used to test the predictive effects of sport type and both interpersonal (i.e., mothers' body dissatisfaction, family dynamics) and intrapersonal factors (i.e., athletic self-efficacy, body mass index [BMI]) on high school female sport participants' (N=627) body dissatisfaction. Sport types were classified as esthetic/lean (i.e., gymnastics), non-esthetic/lean (i.e., cross-country), or non-esthetic/non-lean (i.e., softball). Most participants reported low body dissatisfaction, and body dissatisfaction did not differ across sport types. Nevertheless, mothers' body dissatisfaction was positively associated with daughters' body dissatisfaction for non-esthetic/lean and non-esthetic/non-lean sport participants, and high family cohesion was predictive of body dissatisfaction among non-esthetic/lean sport participants. Across sport types, higher BMI was associated with greater body dissatisfaction, whereas greater athletic self-efficacy was associated with lower body dissatisfaction. These findings highlight the complex relationship between interpersonal and intrapersonal factors and body dissatisfaction in adolescent female sport participants. Copyright © 2012. Published by Elsevier Ltd.

Impact of environmental diversity of hunting complexes in the Lublin region on ontogenetic quality indicators in roe deer (Capreolus capreolus).

PubMed

Czyżowski, Piotr; Drozd, Leszek; Karpiński, Mirosław; Tajchman, Katarzyna; Goleman, Małgorzata; Wojtaś, Justyna; Zieliński, Damian

2018-01-01

Populations of game are not confined to single ecosystems but function within higher-order units, e.g. ecological landscape. The basis for the establishment of the hunting complexes was the assumption that the existing game hunting grounds, i.e. the basic units implementing game management, are too small and do not cover the natural areas inhabited by game populations. Roe deer are flexible species and easily adapt to various site conditions, so they inhabit many different habitats, from large forest complexes, through small in-field tree stands and shrubs, to treeless grounds and field monocultures. The aim of the study was to determine a possible impact of environmental conditions prevailing in the hunting complexes of the Regional Directorate of State Forests (RDLP in Lublin) on the ontogenetic quality of roe deer. The study was conducted on 518 European roe deer ( Capreolus capreolus ) aged from 4 to 7 years (379 bucks and 139 does) harvested within hunting seasons 2010/2011-2013/2014. The results have shown that animals originating from areas with greater forest cover and denser stands are characterised by lower values of the mean ontogenetic quality parameters (carcase weight, kidney fat index, chest girth, weight of antlers) in comparison with animals from typical agricultural areas with fragmented forest complexes. These results indicate that, even in the case of such a eurytopic species as the roe deer, the ontogenetic quality differs between individual hunting complexes. The study has proved that strategies for hunting management of the roe deer should take into account the impact of the landscape structure, which provides a rationale behind creation of hunting complexes.

Enhanced removal of As (V) from aqueous solution using modified hydrous ferric oxide nanoparticles

PubMed Central

Huo, Lijuan; Zeng, Xibai; Su, Shiming; Bai, Lingyu; Wang, Yanan

2017-01-01

Hydrous ferric oxide (HFO) is most effective with high treatment capacity on arsenate [As(V)] sorption although its transformation and aggregation nature need further improvement. Here, HFO nanoparticles with carboxymethyl cellulose (CMC) or starch as modifier was synthesized for the purpose of stability improvement and As(V) removal from water. Comparatively, CMC might be the optimum stabilizer for HFO nanoparticles because of more effective physical and chemical stability. The large-pore structure, high surface specific area, and the non-aggregated nature of CMC-HFO lead to increased adsorption sites, and thus high adsorption capacities of As(V) without pre-treatment (355 mg·g−1), which is much greater than those reported in previous studies. Second-order equation and dual-mode isotherm model could be successfully used to interpret the sorption kinetics and isotherms of As(V), respectively. FTIR, XPS and XRD analyses suggested that precipitation and surface complexation were primary mechanisms for As(V) removal by CMC modified HFO nanoparticles. A surface complexation model (SCM) was used to simulate As adsorption over pH 2.5–10.4. The predominant adsorbed arsenate species were modeled as bidentate binuclear surface complexes at low pH and as monodentate complexes at high pH. The immobilized arsenic remained stable when aging for 270 d at room temperature. PMID:28098196

Enhanced removal of As (V) from aqueous solution using modified hydrous ferric oxide nanoparticles

NASA Astrophysics Data System (ADS)

Huo, Lijuan; Zeng, Xibai; Su, Shiming; Bai, Lingyu; Wang, Yanan

2017-01-01

Hydrous ferric oxide (HFO) is most effective with high treatment capacity on arsenate [As(V)] sorption although its transformation and aggregation nature need further improvement. Here, HFO nanoparticles with carboxymethyl cellulose (CMC) or starch as modifier was synthesized for the purpose of stability improvement and As(V) removal from water. Comparatively, CMC might be the optimum stabilizer for HFO nanoparticles because of more effective physical and chemical stability. The large-pore structure, high surface specific area, and the non-aggregated nature of CMC-HFO lead to increased adsorption sites, and thus high adsorption capacities of As(V) without pre-treatment (355 mg·g-1), which is much greater than those reported in previous studies. Second-order equation and dual-mode isotherm model could be successfully used to interpret the sorption kinetics and isotherms of As(V), respectively. FTIR, XPS and XRD analyses suggested that precipitation and surface complexation were primary mechanisms for As(V) removal by CMC modified HFO nanoparticles. A surface complexation model (SCM) was used to simulate As adsorption over pH 2.5-10.4. The predominant adsorbed arsenate species were modeled as bidentate binuclear surface complexes at low pH and as monodentate complexes at high pH. The immobilized arsenic remained stable when aging for 270 d at room temperature.

Re-evaluation of the origin and evolution of > 4.2 Ga zircons from the Jack Hills metasedimentary rocks

NASA Astrophysics Data System (ADS)

Nemchin, A. A.; Pidgeon, R. T.; Whitehouse, M. J.

2006-04-01

New data are presented on internal structures, U-Pb systematics and oxygen isotope compositions of eight detrital zircons with ages greater than 4.2 Ga, from the Jack Hills metasedimentary belt, Australia. Cathodoluminescence imaging, ion-microprobe U-Pb and oxygen isotope results show evidence for an extensive period of complex zircon growth, secondary reaction and U-Pb isotopic disturbance from 4.36 to 3.90 Ga. In addition many of the zircons have discordant U-Pb systems and excess common Pb indicating a superimposed, relatively recent, reaction between radiation damaged zircon and low temperature fluids. The significance of oxygen isotope compositions for zircons with complex internal structures and U-Pb systems is complicated by uncertainty in the origin of the grains and the unknown effect of later reactions. However, a minority of grains with sharp oscillatory zoning, uniform and concordant U-Pb systems, igneous Th-U ratios and low common Pb contents, are interpreted as undisturbed primary magmatic zircons. The oldest identified, oscillatory zoned, magmatic grain, with an age 4363 ± 20 Ma, is one of a few reported magmatic grains with this age, which is interpreted as the oldest reliable age for Hadean magmatic zircons. Mantle δ18O values are reported for these zircons. Younger oscillatory zoned zircon, including oscillatory zoned cores in complex grains, have δ18O values lower than 6.5‰, which are within the range of ion microprobe analysed δ18O values for zircons in high temperature equilibrium with the normal mantle rocks of 5.3 ± 0.6‰ (2 standard deviations). These values are also within the range of δ18O values found in lunar zircons. The absence of heavy oxygen in the grains that can be interpreted as primary magmatic zircons and the complex history over the period from 4.36 to 3.9 Ga, seen in all other Jack Hills zircons and reflected in the internal structures and U-Pb isotopic systems, questions the model for the early Earth involving long intervals of relatively temperate conditions from 4.4 to 4.0 Ga that were conducive to oceans and possibly life.

Surface complexation and precipitate geometry for aqueous Zn(II) sorption on ferrihydrite: II. XANES analysis and simulation

USGS Publications Warehouse

Waychunas, G.A.; Fuller, C.C.; Davis, J.A.; Rehr, J.J.

2003-01-01

X-ray absorption near-edge spectroscopy (XANES) analysis of sorption complexes has the advantages of high sensitivity (10- to 20-fold greater than extended X-ray absorption fine structure [EXAFS] analysis) and relative ease and speed of data collection (because of the short k-space range). It is thus a potentially powerful tool for characterization of environmentally significant surface complexes and precipitates at very low surface coverages. However, quantitative analysis has been limited largely to "fingerprint" comparison with model spectra because of the difficulty of obtaining accurate multiple-scattering amplitudes for small clusters with high confidence. In the present work, calculations of the XANES for 50- to 200-atom clusters of structure from Zn model compounds using the full multiple-scattering code Feff 8.0 accurately replicate experimental spectra and display features characteristic of specific first-neighbor anion coordination geometry and second-neighbor cation geometry and number. Analogous calculations of the XANES for small molecular clusters indicative of precipitation and sorption geometries for aqueous Zn on ferrihydrite, and suggested by EXAFS analysis, are in good agreement with observed spectral trends with sample composition, with Zn-oxygen coordination and with changes in second-neighbor cation coordination as a function of sorption coverage. Empirical analysis of experimental XANES features further verifies the validity of the calculations. The findings agree well with a complete EXAFS analysis previously reported for the same sample set, namely, that octahedrally coordinated aqueous Zn2+ species sorb as a tetrahedral complex on ferrihydrite with varying local geometry depending on sorption density. At significantly higher densities but below those at which Zn hydroxide is expected to precipitate, a mainly octahedral coordinated Zn2+ precipitate is observed. An analysis of the multiple scattering paths contributing to the XANES demonstrates the importance of scattering paths involving the anion sublattice. We also describe the specific advantages of complementary quantitative XANES and EXAFS analysis and estimate limits on the extent of structural information obtainable from XANES analysis. ?? 2003 Elsevier Science Ltd.

Seismic signals from the slab surface within and downdip of the thrust zone: blind men and the elephant?

NASA Astrophysics Data System (ADS)

Abers, G. A.; Janiszewski, H. A.; Keranen, K. M.; Li, J.; Saffer, D. M.; Shillington, D. J.; Schindler, K.

2016-12-01

The subduction plate interface as been variably described as a narrow discontinuity, a decoupling layer, a viscous channel, or an intensely deformed mixing zone. The 1994 Subduction Conference depicted this ambiguity with the parable of the blind men and the elephant, as participants struggled to rationalize dissimilar observations with an integrated view of subduction. We illustrate here how different seismological tools reveal contradictory natures to the slab surface at 30-80 km depth, highlighting new examples from Alaska and Cascadia. At the km scale and 0.05-0.5 Hz, the teleseismic scattered wavefield that generates receiver functions shows strong consistent patterns. It indicates a uniformly layered plate interface structure with a low-velocity channel along the thrust zone where earthquakes and slow slip events occur. These channels appear homogeneous and 1-4 km thick over wide areas, with hints of strong anisotropy. By contrast, reflection seismology shows complex discontinuous reflectivity packages at the tens of m scale and 5-20 Hz that imply much greater heterogeneity, in both in normal-incidence and wide-angle reflections. To span the intervening frequency band we analyze P-S conversions from in-slab earthquakes recorded nearby, in southern Alaska. These 1-10 Hz signals arrive between P and S and have comparable amplitude, indicating sharp or complex boundaries near the slab surface at 30-50 km depth. However the signals are not uniformly observed and indicate significant heterogeneity in the causative structure. The conversion points lie within those sampled by receiver functions so the differences are not due to geographic variations, and can be analyzed jointly. Taken together, these observations suggest that the same boundary is continuous and relatively homogenous, or highly heterogeneous and laminated, depending on its sampling. They can be reconciled if the structure at km-scale is relatively simple, while it is complex and highly heterogeneous at shorter wavelengths. A complex but sharply bounded low-velocity shear zone best explains these observations, indicating that most deformation is highly localized rather than forming broadly-distributed ductile flow features even well into the aseismic region.

Breakup magmatism on the Vøring Margin, mid-Norway: New insight from interpretation of high-quality 2D and 3D seismic reflection data

NASA Astrophysics Data System (ADS)

Abdelmalak, M. M.; Planke, S.; Millett, J.; Jerram, D. A.; Maharjan, D.; Zastrozhnov, D.; Schmid, D. W.; Faleide, J. I.; Svensen, H.; Myklebust, R.

2017-12-01

The Vøring Margin offshore mid-Norway is a classic volcanic rifted margin, characterized by voluminous Paleogene igneous rocks present on both sides of the continent-ocean boundary. The margin displays (1) thickened transitional crust with a well-defined lower crustal high-velocity body and prominent deep crustal reflections, the so-called T-Reflection, (2) seaward dipping reflector (SDR) wedges and a prominent northeast-trending escarpment on the Vøring Marginal High, and (3) extensive sill complexes in the adjacent Cretaceous Vøring Basin. During the last decade, new 2D and 3D industry seismic data along with improved processing techniques, such as broadband processing and noise reduction processing sequences, have made it possible to image and map the breakup igneous complex in much greater detail than previously possible. Our interpretation includes a combination of (1) seismic horizon picking, (2) integrated seismic-gravity-magnetic (SGM) interpretation, (3) seismic volcanostratigraphy, and (4) igneous seismic geomorphology. The results are integrated with published wide-angle seismic data, re-analyzed borehole data including new geochronology, and new geodynamic modeling of the effects of magmatism on the thermal history and subsidence of the margin. The extensive sill complexes and associated hydrothermal vent complexes in the Vøring Basin have a Paleocene-Eocene boundary age based on high-precision U/Pb dating combined with seismic mapping constraints. On the marginal high, our results show a highly variable crustal structure, with a pre-breakup configuration consisting of large-scale structural highs and sedimentary basins. These structures were in-filled and covered by basalt flows and volcanogenic sediments during the early stages of continental breakup in the earliest Eocene. Subsequently, rift basins developed along the continent-ocean boundary and where infilled by up to ca. 6 km thick basalt sequences, currently imaged as SDRs fed by a dike swarm imaged on seismic data. The addition of magma within the crust had a prominent effect on the thermal history and hydrocarbon maturation of the sedimentary basin, causing uplift, delayed subsidence, and possibly contributing to the triggering of global warming during the Paleocene-Eocene Thermal Maximum (PETM).

Syntheses, crystal structures and properties of novel copper(II) complexes obtained by reactions of copper(II) sulfate pentahydrate with tripodal ligands.

PubMed

Zhao, Wei; Fan, Jian; Song, You; Kawaguchi, Hiroyuki; Okamura, Taka-aki; Sun, Wei-Yin; Ueyama, Norikazu

2005-04-21

Three novel metal-organic frameworks (MOFs), [Cu(1)SO4].H2O (4), [Cu2(2)2(SO4)2].4H2O (5) and [Cu(3)(H2O)]SO4.5.5H2O (6), were obtained by hydrothermal reactions of CuSO4.5H2O with the corresponding ligands, which have different flexibility. The structures of the synthesized complexes were determined by single-crystal X-ray diffraction analyses. Complex 4 has a 2D network structure with two types of metallacycles. Complex 5 also has a 2D network structure in which each independent 2D sheet contains two sub-layers bridged by oxygen atoms of the sulfate anions. Complex 6 has a 2D puckered structure in which the sulfate anions serve as counter anions, which are different from those in complexes 4 (terminators) and 5 (bridges). The different structures of complexes 4, 5 and 6 indicate that the nature of organic ligands affected the structures of the assemblies greatly. The magnetic behavior of complex 5 and anion-exchange properties of complex 6 were investigated.

Solving a meiotic LEGO puzzle: transverse filaments and the assembly of the synaptonemal complex in Caenorhabditis elegans.

PubMed

Hawley, R Scott

2011-10-01

The structure of the meiosis-specific synaptonemal complex, which is perhaps the central visible characteristic of meiotic prophase, has been a matter of intense interest for decades. Although a general picture of the interactions between the transverse filament proteins that create this structure has emerged from studies in a variety of organisms, a recent analysis of synaptonemal complex structure in Caenorhabditis elegans by Schild-Prüfert et al. (2011) has provided the clearest picture of the structure of the architecture of a synaptonemal complex to date. Although the transverse filaments of the worm synaptonemal complex are assembled differently then those observed in yeast, mammalian, and Drosophila synaptonemal complexes, a comparison of the four assemblies shows that achieving the overall basic structure of the synaptonemal complex is far more crucial than conserving the structures of the individual transverse filaments.

A tabu search evalutionary algorithm for multiobjective optimization: Application to a bi-criterion aircraft structural reliability problem

NASA Astrophysics Data System (ADS)

Long, Kim Chenming

Real-world engineering optimization problems often require the consideration of multiple conflicting and noncommensurate objectives, subject to nonconvex constraint regions in a high-dimensional decision space. Further challenges occur for combinatorial multiobjective problems in which the decision variables are not continuous. Traditional multiobjective optimization methods of operations research, such as weighting and epsilon constraint methods, are ill-suited to solving these complex, multiobjective problems. This has given rise to the application of a wide range of metaheuristic optimization algorithms, such as evolutionary, particle swarm, simulated annealing, and ant colony methods, to multiobjective optimization. Several multiobjective evolutionary algorithms have been developed, including the strength Pareto evolutionary algorithm (SPEA) and the non-dominated sorting genetic algorithm (NSGA), for determining the Pareto-optimal set of non-dominated solutions. Although numerous researchers have developed a wide range of multiobjective optimization algorithms, there is a continuing need to construct computationally efficient algorithms with an improved ability to converge to globally non-dominated solutions along the Pareto-optimal front for complex, large-scale, multiobjective engineering optimization problems. This is particularly important when the multiple objective functions and constraints of the real-world system cannot be expressed in explicit mathematical representations. This research presents a novel metaheuristic evolutionary algorithm for complex multiobjective optimization problems, which combines the metaheuristic tabu search algorithm with the evolutionary algorithm (TSEA), as embodied in genetic algorithms. TSEA is successfully applied to bicriteria (i.e., structural reliability and retrofit cost) optimization of the aircraft tail structure fatigue life, which increases its reliability by prolonging fatigue life. A comparison for this application of the proposed algorithm, TSEA, with several state-of-the-art multiobjective optimization algorithms reveals that TSEA outperforms these algorithms by providing retrofit solutions with greater reliability for the same costs (i.e., closer to the Pareto-optimal front) after the algorithms are executed for the same number of generations. This research also demonstrates that TSEA competes with and, in some situations, outperforms state-of-the-art multiobjective optimization algorithms such as NSGA II and SPEA 2 when applied to classic bicriteria test problems in the technical literature and other complex, sizable real-world applications. The successful implementation of TSEA contributes to the safety of aeronautical structures by providing a systematic way to guide aircraft structural retrofitting efforts, as well as a potentially useful algorithm for a wide range of multiobjective optimization problems in engineering and other fields.

The dynamic relationship between cerebellar Purkinje cell simple spikes and the spikelet number of complex spikes.

PubMed

Burroughs, Amelia; Wise, Andrew K; Xiao, Jianqiang; Houghton, Conor; Tang, Tianyu; Suh, Colleen Y; Lang, Eric J; Apps, Richard; Cerminara, Nadia L

2017-01-01

Purkinje cells are the sole output of the cerebellar cortex and fire two distinct types of action potential: simple spikes and complex spikes. Previous studies have mainly considered complex spikes as unitary events, even though the waveform is composed of varying numbers of spikelets. The extent to which differences in spikelet number affect simple spike activity (and vice versa) remains unclear. We found that complex spikes with greater numbers of spikelets are preceded by higher simple spike firing rates but, following the complex spike, simple spikes are reduced in a manner that is graded with spikelet number. This dynamic interaction has important implications for cerebellar information processing, and suggests that complex spike spikelet number may maintain Purkinje cells within their operational range. Purkinje cells are central to cerebellar function because they form the sole output of the cerebellar cortex. They exhibit two distinct types of action potential: simple spikes and complex spikes. It is widely accepted that interaction between these two types of impulse is central to cerebellar cortical information processing. Previous investigations of the interactions between simple spikes and complex spikes have mainly considered complex spikes as unitary events. However, complex spikes are composed of an initial large spike followed by a number of secondary components, termed spikelets. The number of spikelets within individual complex spikes is highly variable and the extent to which differences in complex spike spikelet number affects simple spike activity (and vice versa) remains poorly understood. In anaesthetized adult rats, we have found that Purkinje cells recorded from the posterior lobe vermis and hemisphere have high simple spike firing frequencies that precede complex spikes with greater numbers of spikelets. This finding was also evident in a small sample of Purkinje cells recorded from the posterior lobe hemisphere in awake cats. In addition, complex spikes with a greater number of spikelets were associated with a subsequent reduction in simple spike firing rate. We therefore suggest that one important function of spikelets is the modulation of Purkinje cell simple spike firing frequency, which has implications for controlling cerebellar cortical output and motor learning. © 2016 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

The effect of structural complexity, prey density, and "predator-free space" on prey survivorship at created oyster reef mesocosms

USGS Publications Warehouse

Humphries, Austin T.; La Peyre, Megan K.; Decossas, Gary A.

2011-01-01

Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and “predator-free space” to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of “predator-free space” was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require “predator-free space” measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of “predator-free space” are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats.

78 FR 47463 - Self-Regulatory Organizations; BOX Options Exchange LLC; Notice of Filing of a Proposed Rule...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-05

... Filter July 30, 2013. Pursuant to Section 19(b)(1) of the Securities Exchange Act of 1934 (``Act''),\\1... filtering inbound Complex Orders \\3\\ (the ``Complex Order Filter''). The proposed rule change would make the... proposed Complex Order Filter will simplify the filtering procedure, provide greater flexibility to...

Anisotropy of magnetic susceptibility (AMS) in the Siilinjärvi carbonatite complex, eastern Finland

NASA Astrophysics Data System (ADS)

Almqvist, Bjarne; Karell, Fredrik; Högdahl, Karin; Malehmir, Alireza; Heino, Pasi; Salo, Aleksi

2017-04-01

We present a set of AMS measurements on samples from the Siilinjärvi alkaline-carbonatite complex in eastern Finland. The complex has a tabular shape (ca. 16 km long, 1.5 km wide) that strikes north-south and is constrained within a steeply dipping N-S oriented deformation zone. It consists of a mixture of lithologies, including carbonatite, fenite and glimmerite (mica-rich rocks), which is hosted within a Precambrian granite and gneiss. After emplacement of the carbonatite, the complex was subsequently intruded by diabase dykes. Deformation has occurred in several episodes after dyke intrusions, and strain is heterogeneously distributed among the different lithologies. Strain localizes mainly within glimmerite and carbonatite, and at the contacts between dykes and glimmerite/carbonatite where shear zones develop locally. Structures provide indications for both simple (strike-slip) and pure shear components in the deformation history of the complex, although the former may dominate. Thirty-six localities were sampled, providing 272 specimens for AMS measurements, within the southern and eastern parts of the Siilinjärvi open-pit mine (within the complex), mainly from diabase dykes, glimmerite and carbonatites; a smaller number of samples were collected from fenite. Sampling was carried out in order to investigate magnetic fabrics in relation to the emplacement of the dykes and their structural relationship to the glimmerite/carbonatite. Structural measurements were made to accompany the magnetic fabric study. The magnetic fabric shows a magnetic foliation plane that is oriented north-south, with sub-horizontal k3-axes oriented nearly east-west. Magnetic lineation (k1) clusters sub-vertically, but does show a tendency to spread along the north-south magnetic foliation great circle. The dataset can be further divided into two sub-sets based on the bulk susceptibility (km) and degree of anisotropy (P). The bulk of the data set ( 70 %), belonging to samples of diabase, is characterized by bulk susceptibility ranging from 1.26e-4 to 1.29e-3 [SI], and P <1.15 (i.e., <15 %). Glimmerites (and carbonatites) show considerably higher bulk susceptibility (4.27e-4 to 2.09e-1 [SI]) and P (up to 1.61), indicative of 1) a much higher magnetite content and 2) larger strain. The glimmerite/carbonatite shows a well-defined N-S magnetic lineation, with k1 and k2 dispersed along the foliation great circle. The diabase AMS shows greater scattering when considering the complete data set, which is likely tied to the individual orientations of dykes in the complex. Ongoing analysis focuses on the details of structural and AMS relationships, between dykes and glimmerite/carbonatite, in order to unravel their emplacement and subsequent deformation. This study was carried out within the ERA-MIN 1 StartGeoDelineation project sponsored by Vinnova (project number 2014-06238), SGU, Tekes, Nordic Iron Ore, and Yara.

Structure, recognition and adaptive binding in RNA aptamer complexes.

PubMed

Patel, D J; Suri, A K; Jiang, F; Jiang, L; Fan, P; Kumar, R A; Nonin, S

1997-10-10

Novel features of RNA structure, recognition and discrimination have been recently elucidated through the solution structural characterization of RNA aptamers that bind cofactors, aminoglycoside antibiotics, amino acids and peptides with high affinity and specificity. This review presents the solution structures of RNA aptamer complexes with adenosine monophosphate, flavin mononucleotide, arginine/citrulline and tobramycin together with an example of hydrogen exchange measurements of the base-pair kinetics for the AMP-RNA aptamer complex. A comparative analysis of the structures of these RNA aptamer complexes yields the principles, patterns and diversity associated with RNA architecture, molecular recognition and adaptive binding associated with complex formation.

Principles of assembly reveal a periodic table of protein complexes.

PubMed

Ahnert, Sebastian E; Marsh, Joseph A; Hernández, Helena; Robinson, Carol V; Teichmann, Sarah A

2015-12-11

Structural insights into protein complexes have had a broad impact on our understanding of biological function and evolution. In this work, we sought a comprehensive understanding of the general principles underlying quaternary structure organization in protein complexes. We first examined the fundamental steps by which protein complexes can assemble, using experimental and structure-based characterization of assembly pathways. Most assembly transitions can be classified into three basic types, which can then be used to exhaustively enumerate a large set of possible quaternary structure topologies. These topologies, which include the vast majority of observed protein complex structures, enable a natural organization of protein complexes into a periodic table. On the basis of this table, we can accurately predict the expected frequencies of quaternary structure topologies, including those not yet observed. These results have important implications for quaternary structure prediction, modeling, and engineering. Copyright © 2015, American Association for the Advancement of Science.

Structural investigation of the β-cyclodextrin complexes with chiral bicyclic monoterpenes - Influence of the functionality group on the host-guest stoichiometry

NASA Astrophysics Data System (ADS)

Ceborska, Magdalena

2017-10-01

The crystal structures of the complexes of β-cyclodextrin with (+)- and (-)-camphors are presented. The comparison of the obtained crystal structures with available data for other complexes of β-cyclodextrin with chiral bicyclic monoterpenes (hydrocarbon (+)-fenchene and alcohols: (-)-isopinocampheol, and (+)-, and (-)-borneols) obtained from Cambridge Structural Database (CSD) shows the trend of alcohols to form dimeric complexes of 2:3 stoichiometry, while hydrocarbons and ketones prefer to form 2:2 host-guest inclusion complexes.

Tannins, Peptic Ulcers and Related Mechanisms

PubMed Central

de Jesus, Neyres Zinia Taveira; de Souza Falcão, Heloina; Gomes, Isis Fernandes; de Almeida Leite, Thiago Jose; de Morais Lima, Gedson Rodrigues; Barbosa-Filho, Jose Maria; Tavares, Josean Fechine; da Silva, Marcelo Sobral; de Athayde-Filho, Petrônio Filgueiras; Batista, Leonia Maria

2012-01-01

This review of the current literature aims to study correlations between the chemical structure and gastric anti-ulcer activity of tannins. Tannins are used in medicine primarily because of their astringent properties. These properties are due to the fact that tannins react with the tissue proteins with which they come into contact. In gastric ulcers, this tannin-protein complex layer protects the stomach by promoting greater resistance to chemical and mechanical injury or irritation. Moreover, in several experimental models of gastric ulcer, tannins have been shown to present antioxidant activity, promote tissue repair, exhibit anti Helicobacter pylori effects, and they are involved in gastrointestinal tract anti-inflammatory processes. The presence of tannins explains the anti-ulcer effects of many natural products. PMID:22489149

Personality disorder assessment: the challenge of construct validity.

PubMed

Clark, L A; Livesley, W J; Morey, L

1997-01-01

We begin with a review of the data that challenge the current categorical system for classifying personality disorder, focusing on the central assessment issues of convergent and discriminant validity. These data indicate that while there is room for improvement in assessment, even greater change is needed in conceptualization than in instrumentation. Accordingly, we then refocus the categorical-dimensional debate in assessment terms, and place it in the broader context of such issues as the hierarchical structure of personality, overlap and distinctions between normal and abnormal personality, sources of information in personality disorder assessment, and overlap and discrimination of trait and state assessment. We conclude that more complex conceptual models that can incorporate both biological and environmental influences on the development of adaptive and maladaptive personality are needed.

Recent advances in "bioartificial polymeric materials" based nanovectors

NASA Astrophysics Data System (ADS)

Conte, Raffaele; De Luca, Ilenia; Valentino, Anna; Di Salle, Anna; Calarco, Anna; Riccitiello, Francesco; Peluso, Gianfranco

2017-04-01

This chapter analyzes the advantages of the use of bioartificial polymers as carriers and the main strategies used for their design. Despite the enormous progresses in this field, more studies are required for the fully evaluation of these nanovectors in complex organisms and for the characterization of the pharmacodynamic and pharmacokinetic of the loaded drugs. Moreover, progresses in polymer chemistry are introducing a wide range of functionalities in the bioartificial polymeric material (BPM) nanostructures leading to a second generation of bioartificial polymer therapeutics based on novel and heterogeneous architectures with higher molecular weight and predictable structures, in order to achieve greater multivalency and increased loading capacity. Therefore, research on bioartificial polymeric nanovectors is an "on-going" field capable of attracting medical interest.

Biosynthetic approaches to creating bioactive fungal metabolites: Pathway engineering and activation of secondary metabolism.

PubMed

Motoyama, Takayuki; Osada, Hiroyuki

2016-12-15

The diversity of natural products is greater than that of combinatorial chemistry compounds and is similar to that of drugs. Compounds rich in sp 3 carbons, such as natural products, typically exhibit high structural complexity and high specificity to molecular targets. Microorganisms can synthesize such sp 3 carbon-rich compounds and can be used as excellent factories for making bioactive compounds. Here, we mainly focus on pathway engineering of two sp 3 carbon-rich bioactive indole alkaloids, fumitremorgin C and terpendole E. We also demonstrate the importance of activation of secondary metabolism by focusing on tenuazonic acid, a bioactive tetramic acid compound, as an example. Copyright © 2016 Elsevier Ltd. All rights reserved.

Broadband gradient index microwave quasi-optical elements based on non-resonant metamaterials.

PubMed

Liu, Ruopeng; Cheng, Qiang; Chin, Jessie Y; Mock, Jack J; Cui, Tie Jun; Smith, David R

2009-11-09

Utilizing non-resonant metamaterial elements, we demonstrate that complex gradient index optics can be constructed exhibiting low material losses and large frequency bandwidth. Although the range of structures is limited to those having only electric response, with an electric permittivity always equal to or greater than unity, there are still numerous metamaterial design possibilities enabled by leveraging the non-resonant elements. For example, a gradient, impedance matching layer can be added that drastically reduces the return loss of the optical elements due to reflection. In microwave experiments, we demonstrate the broadband design concepts with a gradient index lens and a beam-steering element, both of which are confirmed to operate over the entire X-band (roughly 8-12 GHz) frequency spectrum.

Bomb or Boon: Linking Population, People and Power in Fragile Regions: Comment on "The Pill Is Mightier Than the Sword".

PubMed

Gilpin, Raymond

2015-10-02

The relationship between population structure and violent conflict is complex and heavily dependent on the behavior of other variables like governance, economic prospects, and urbanization. While addressing rapid population growth might be a necessary condition for peace, it is by no means sufficient. Concomitant steps must also be taken to foster inclusivity, guarantee broader rights for all, particularly women, rebuild social contracts and ensure that all citizens have equal access to economic opportunity. Measures to control family size could reduce dependency and create greater socio-economic opportunities for women and youth, By so doing, the "youth bulge" phenomenon could be a boon for rapidly growing developing countries. © 2016 by Kerman University of Medical Sciences.

Changes in habitat complexity negatively affect diverse gastropod assemblages in coralline algal turf.

PubMed

Kelaher, B P

2003-05-01

The physical structure of a habitat generally has a strong influence on the diversity and abundance of associated organisms. I investigated the role of coralline algal turf structure in determining spatial variation of gastropod assemblages at different tidal heights of a rocky shore near Sydney, Australia. The structural characteristics of algal turf tested were frond density (or structural complexity) and frond length (the vertical scale over which structural complexity was measured). This definition of structural complexity assumes that complexity of the habitat increases with increasing frond density. While frond length was unrelated to gastropod community structure, I found significant correlations between density of fronds and multivariate and univariate measures of gastropod assemblages, indicating the importance of structural complexity. In contrast to previous studies, here there were negative relationships between the density of fronds and the richness and abundance of gastropods. Artificial habitat mimics were used to manipulate the density of fronds to test the hypothesis that increasing algal structural complexity decreases the richness and abundance of gastropods. As predicted, there were significantly more species of gastropods in loosely packed than in tightly packed turf at both low- and mid-shore levels. Despite large differences between gastropod assemblages at different tidal heights, the direction and magnitude of these negative effects were similar at low- and mid-shore levels and, therefore, relatively independent of local environmental conditions. These novel results extend our previous understanding of the ecological effects of habitat structure because they demonstrate possible limitations of commonly used definitions of structural complexity, as well as distinct upper thresholds in the relationship between structural complexity and faunal species richness.

Habitat Complexity in Aquatic Microcosms Affects Processes Driven by Detritivores

PubMed Central

Flores, Lorea; Bailey, R. A.; Elosegi, Arturo; Larrañaga, Aitor; Reiss, Julia

2016-01-01

Habitat complexity can influence predation rates (e.g. by providing refuge) but other ecosystem processes and species interactions might also be modulated by the properties of habitat structure. Here, we focussed on how complexity of artificial habitat (plastic plants), in microcosms, influenced short-term processes driven by three aquatic detritivores. The effects of habitat complexity on leaf decomposition, production of fine organic matter and pH levels were explored by measuring complexity in three ways: 1. as the presence vs. absence of habitat structure; 2. as the amount of structure (3 or 4.5 g of plastic plants); and 3. as the spatial configuration of structures (measured as fractal dimension). The experiment also addressed potential interactions among the consumers by running all possible species combinations. In the experimental microcosms, habitat complexity influenced how species performed, especially when comparing structure present vs. structure absent. Treatments with structure showed higher fine particulate matter production and lower pH compared to treatments without structures and this was probably due to higher digestion and respiration when structures were present. When we explored the effects of the different complexity levels, we found that the amount of structure added explained more than the fractal dimension of the structures. We give a detailed overview of the experimental design, statistical models and R codes, because our statistical analysis can be applied to other study systems (and disciplines such as restoration ecology). We further make suggestions of how to optimise statistical power when artificially assembling, and analysing, ‘habitat complexity’ by not confounding complexity with the amount of structure added. In summary, this study highlights the importance of habitat complexity for energy flow and the maintenance of ecosystem processes in aquatic ecosystems. PMID:27802267

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Jiang Ping; Yan, Zhi Shuo; Long, Ji Ying

By using a rigid dicarboxylate ligand, 4,5-di(4′-carboxylphenyl)benzene (H{sub 2}L), two complexes formulated as SrL(DMF)(H{sub 2}O)·(CH{sub 3}CN) (DMF=N,N′-dimethylformamide) (1) and BaL(H{sub 2}O){sub 2} (2) were solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complexes 1 and 2 display two-dimensional (2D) layer structures. The two complexes exhibit different electrochemical and photoelectrochemical properties. Their thermal stabilities, cyclic voltammograms, UV–vis absorption and diffuse reflectance spectra and photoluminescence properties have been investigated. The band structures, the total density of states (TDOS) and partial density of states (PDOS) of the two complexes were calculated by CASTEP program. Complex 2 exhibits much higher photocurrent density thanmore » complex 1. The Mott–Schottky plots reveal that complexes 1 and 2 both are p-type semiconductors, which are in agreement with their band structure calculations. - Graphical abstract: Two alkaline earth metal(II) complexes with 2D layer structures are p-type semiconductors, they possess different band structures and density of states. And the Ba(II) complex 2 exhibits much higher photocurrent density than the Sr(II) complex 1.« less

Complexity in language learning and treatment.

PubMed

Thompson, Cynthia K

2007-02-01

To introduce a Clinical Forum focused on the Complexity Account of Treatment Efficacy (C. K. Thompson, L. P. Shapiro, S. Kiran, & J. Sobecks, 2003), a counterintuitive but effective approach for treating language disorders. This approach espouses training complex structures to promote generalized improvement of simpler, linguistically related structures. Three articles are included, addressing complexity in treatment of phonology, lexical-semantics, and syntax. Complexity hierarchies based on models of normal language representation and processing are discussed in each language domain. In addition, each article presents single-subject controlled experimental studies examining the complexity effect. By counterbalancing treatment of complex and simple structures across participants, acquisition and generalization patterns are examined as they emerge. In all language domains, cascading generalization occurs from more to less complex structures; however, the opposite pattern is rarely seen. The results are robust, with replication within and across participants. The construct of complexity appears to be a general principle that is relevant to treating a range of language disorders in both children and adults. While challenging the long-standing clinical notion that treatment should begin with simple structures, mounting evidence points toward the facilitative effects of using more complex structures as a starting point for treatment.

Crystal structure of mitochondrial respiratory membrane protein complex II.

PubMed

Sun, Fei; Huo, Xia; Zhai, Yujia; Wang, Aojin; Xu, Jianxing; Su, Dan; Bartlam, Mark; Rao, Zihe

2005-07-01

The mitochondrial respiratory Complex II or succinate:ubiquinone oxidoreductase (SQR) is an integral membrane protein complex in both the tricarboxylic acid cycle and aerobic respiration. Here we report the first crystal structure of Complex II from porcine heart at 2.4 A resolution and its complex structure with inhibitors 3-nitropropionate and 2-thenoyltrifluoroacetone (TTFA) at 3.5 A resolution. Complex II is comprised of two hydrophilic proteins, flavoprotein (Fp) and iron-sulfur protein (Ip), and two transmembrane proteins (CybL and CybS), as well as prosthetic groups required for electron transfer from succinate to ubiquinone. The structure correlates the protein environments around prosthetic groups with their unique midpoint redox potentials. Two ubiquinone binding sites are discussed and elucidated by TTFA binding. The Complex II structure provides a bona fide model for study of the mitochondrial respiratory system and human mitochondrial diseases related to mutations in this complex.

Structure-Based Characterization of Multiprotein Complexes

PubMed Central

Wiederstein, Markus; Gruber, Markus; Frank, Karl; Melo, Francisco; Sippl, Manfred J.

2014-01-01

Summary Multiprotein complexes govern virtually all cellular processes. Their 3D structures provide important clues to their biological roles, especially through structural correlations among protein molecules and complexes. The detection of such correlations generally requires comprehensive searches in databases of known protein structures by means of appropriate structure-matching techniques. Here, we present a high-speed structure search engine capable of instantly matching large protein oligomers against the complete and up-to-date database of biologically functional assemblies of protein molecules. We use this tool to reveal unseen structural correlations on the level of protein quaternary structure and demonstrate its general usefulness for efficiently exploring complex structural relationships among known protein assemblies. PMID:24954616

Effects of Chain Length and Degree of Unsaturation of Fatty Acids on Structure and in Vitro Digestibility of Starch-Protein-Fatty Acid Complexes.

PubMed

Zheng, Mengge; Chao, Chen; Yu, Jinglin; Copeland, Les; Wang, Shuo; Wang, Shujun

2018-02-28

The effects of chain length and degree of unsaturation of fatty acids (FAs) on structure and in vitro digestibility of starch-protein-FA complexes were investigated in model systems. Studies with the rapid visco analyzer (RVA) showed that the formation of ternary complex resulted in higher viscosities than those of binary complex during the cooling and holding stages. The results of differential scanning calorimetry (DSC), Raman, and X-ray diffraction (XRD) showed that the structural differences for ternary complexes were much less than those for binary complexes. Starch-protein-FA complexes presented lower in vitro enzymatic digestibility compared with starch-FAs complexes. We conclude that shorter chain and lower unsaturation FAs favor the formation of ternary complexes but decrease the thermal stability of these complexes. FAs had a smaller effect on the ordered structures of ternary complexes than on those of binary complexes and little effect on enzymatic digestibility of both binary and ternary complexes.

Brain alpha-ketoglutarate dehydrogenase complex: kinetic properties, regional distribution, and effects of inhibitors.

PubMed

Lai, J C; Cooper, A J

1986-11-01

The substrate and cofactor requirements and some kinetic properties of the alpha-ketoglutarate dehydrogenase complex (KGDHC; EC 1.2.4.2, EC 2.3.1.61, and EC 1.6.4.3) in purified rat brain mitochondria were studied. Brain mitochondrial KGDHC showed absolute requirement for alpha-ketoglutarate, CoA and NAD, and only partial requirement for added thiamine pyrophosphate, but no requirement for Mg2+ under the assay conditions employed in this study. The pH optimum was between 7.2 and 7.4, but, at pH values below 7.0 or above 7.8, KGDHC activity decreased markedly. KGDHC activity in various brain regions followed the rank order: cerebral cortex greater than cerebellum greater than or equal to midbrain greater than striatum = hippocampus greater than hypothalamus greater than pons and medulla greater than olfactory bulb. Significant inhibition of brain mitochondrial KGDHC was noted at pathological concentrations of ammonia (0.2-2 mM). However, the purified bovine heart KGDHC and KGDHC activity in isolated rat heart mitochondria were much less sensitive to inhibition. At 5 mM both beta-methylene-D,L-aspartate and D,L-vinylglycine (inhibitors of cerebral glucose oxidation) inhibited the purified heart but not the brain mitochondrial enzyme complex. At approximately 10 microM, calcium slightly stimulated (by 10-15%) the brain mitochondrial KGDHC. At concentrations above 100 microM, calcium (IC50 = 1 mM) inhibited both brain mitochondrial and purified heart KGDHC. The present results suggest that some of the kinetic properties of the rat brain mitochondrial KGDHC differ from those of the purified bovine heart and rat heart mitochondrial enzyme complexes. They also suggest that the inhibition of KGDHC by ammonia and the consequent effect on the citric acid cycle fluxes may be of pathophysiological and/or pathogenetic importance in hyperammonemia and in diseases (e.g., hepatic encephalopathy, inborn errors of urea metabolism, Reye's syndrome) where hyperammonemia is a consistent feature. Brain accumulation of calcium occurs in a number of pathological conditions. Therefore, it is possible that such a calcium accumulation may have a deleterious effect on KGDHC activity.