Energetics analysis of interstitial loops in single-phase concentrated solid-solution alloys

NASA Astrophysics Data System (ADS)

Wang, Xin-Xin; Niu, Liang-Liang; Wang, Shaoqing

2018-04-01

Systematic energetics analysis on the shape preference, relative stability and radiation-induced segregation of interstitial loops in nickel-containing single-phase concentrated solid-solution alloys have been conducted using atomistic simulations. It is shown that the perfect loops prefer rhombus shape for its low potential energy, while the Frank faulted loops favor ellipse for its low potential energy and the possible large configurational entropy. The decrease of stacking fault energy with increasing compositional complexity provides the energetic driving force for the formation of faulted loops, which, in conjunction with the kinetic factors, explains the experimental observation that the fraction of faulted loops rises with increasing compositional complexity. Notably, the kinetics is primarily responsible for the absence of faulted loops in nickel-cobalt with a very low stacking fault energy. We further demonstrate that the simultaneous nickel enrichment and iron/chromium depletion on interstitial loops can be fully accounted for by their energetics.

Photoactive energetic materials

DOEpatents

Chavez, David E.; Hanson, Susan Kloek; Scharff, Robert Jason; Veauthier, Jacqueline Marie; Myers, Thomas Winfield

2018-02-27

Energetic materials that are photoactive or believed to be photoactive may include a conventional explosive (e.g. PETN, nitroglycerine) derivatized with an energetic UV-absorbing and/or VIS-absorbing chromophore such as 1,2,4,5-tetrazine or 1,3,5-triazine. Absorption of laser light having a suitably chosen wavelength may result in photodissociation, decomposition, and explosive release of energy. These materials may be used as ligands to form complexes. Coordination compounds include such complexes with counterions. Some having the formula M(L).sub.n.sup.2+ were synthesized, wherein M is a transition metal and L is a ligand and n is 2 or 3. These may be photoactive upon exposure to a laser light beam having an appropriate wavelength of UV light, near-IR and/or visible light. Photoactive materials also include coordination compounds bearing non-energetic ligands; in this case, the counterion may be an oxidant such as perchlorate.

VLF and X-ray Instruments for Stratospheric Balloons: ABOVE2 and EPEx

NASA Astrophysics Data System (ADS)

Cully, C. M.; Galts, D.; Patrick, M.; Duffin, C.; Jang, A. C.; Pitzel, J.; Trumpour, T.; McCarthy, M.; Milling, D. K.

2017-12-01

The ABOVE2 (2016) and EPEx (2018) stratospheric balloon missions are designed to study energetic electrons precipitating from the radiation belts into the atmosphere. The payloads include instruments that measure Very Low Frequency (VLF) magnetic and electric fields, and bremsstrahlung X-rays. The ABOVE2 VLF instrument is an FPGA-based design with >200 kHz sampling rates, sub-microsecond timing accuracy and onboard spectral processing, designed in a Cubesat-friendly format. The EPEx X-ray instrument is a hard X-ray imaging system, also in a Cubesat-friendly format, incorporating a commercially-available Cadmium-Zinc-Telluride module. The imager is sufficiently lightweight that we can launch it on-demand with low-volume latex balloons. I will discuss the design and performance of both instruments, and present data from the ABOVE2 flights.

Activity of Pure Streptovaricins and Fractionated Streptovaricin Complex Against Friend Virus

PubMed Central

Horoszewicz, Julius S.; Rinehart, Kenneth L.; Leong, Susan S.; Carter, William A.

1975-01-01

Chromatographic fractionation of streptovaricin complex yields two stable components enriched (4- to 16-fold) in activity directed against the polycythemic strain of Friend virus; both components apparently contain no streptovaricins. When compared with their unfractionated parent streptovaricin complex, eight individual intact streptovaricins (A through G and J) show at least a 30-fold reduction in antiviral activity. These results further support the conclusion that the diversified biological properties of streptovaricin complex probably reside in different molecular structures. PMID:237470

Nitrogen-Rich Energetic Metal-Organic Framework: Synthesis, Structure, Properties, and Thermal Behaviors of Pb(II) Complex Based on N,N-Bis(1H-tetrazole-5-yl)-Amine

PubMed Central

Liu, Qiangqiang; Jin, Bo; Zhang, Qingchun; Shang, Yu; Guo, Zhicheng; Tan, Bisheng; Peng, Rufang

2016-01-01

The focus of energetic materials is on searching for a high-energy, high-density, insensitive material. Previous investigations have shown that 3D energetic metal–organic frameworks (E-MOFs) have great potential and advantages in this field. A nitrogen-rich E-MOF, Pb(bta)·2H2O [N% = 31.98%, H2bta = N,N-Bis(1H-tetrazole-5-yl)-amine], was prepared through a one-step hydrothermal reaction in this study. Its crystal structure was determined through single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, and elemental analysis. The complex has high heat denotation (16.142 kJ·cm−3), high density (3.250 g·cm−3), and good thermostability (Tdec = 614.9 K, 5 K·min−1). The detonation pressure and velocity obtained through theoretical calculations were 43.47 GPa and 8.963 km·s−1, respectively. The sensitivity test showed that the complex is an impact-insensitive material (IS > 40 J). The thermal decomposition process and kinetic parameters of the complex were also investigated through thermogravimetry and differential scanning calorimetry. Non-isothermal kinetic parameters were calculated through the methods of Kissinger and Ozawa-Doyle. Results highlighted the nitrogen-rich MOF as a potential energetic material. PMID:28773805

Dynamics of embedded curves by doubly-nonlocal reaction-diffusion systems

NASA Astrophysics Data System (ADS)

von Brecht, James H.; Blair, Ryan

2017-11-01

We study a class of nonlocal, energy-driven dynamical models that govern the motion of closed, embedded curves from both an energetic and dynamical perspective. Our energetic results provide a variety of ways to understand physically motivated energetic models in terms of more classical, combinatorial measures of complexity for embedded curves. This line of investigation culminates in a family of complexity bounds that relate a rather broad class of models to a generalized, or weighted, variant of the crossing number. Our dynamic results include global well-posedness of the associated partial differential equations, regularity of equilibria for these flows as well as a more detailed investigation of dynamics near such equilibria. Finally, we explore a few global dynamical properties of these models numerically.

Complexation of C60 fullerene with aromatic drugs.

PubMed

Evstigneev, Maxim P; Buchelnikov, Anatoly S; Voronin, Dmitry P; Rubin, Yuriy V; Belous, Leonid F; Prylutskyy, Yuriy I; Ritter, Uwe

2013-02-25

The contributions of various physical factors to the energetics of complexation of aromatic drug molecules with C(60) fullerene are investigated in terms of the calculated magnitudes of equilibrium complexation constants and the components of the net Gibbs free energy. Models of complexation are developed taking into account the polydisperse nature of fullerene solutions in terms of the continuous or discrete (fractal) aggregation of C(60) molecules. Analysis of the energetics has shown that stabilization of the ligand-fullerene complexes in aqueous solution is mainly determined by intermolecular van der Waals interactions and, to lesser extent, by hydrophobic interactions. The results provide a physicochemical basis for a potentially new biotechnological application of fullerenes as modulators of biological activity of aromatic drugs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanisms and Kinetics of Alkaline Hydrolysis of the Energetic Nitroaromatic Compounds 2,4,6-Trinitrotoluene (TNT) and 2,4-Dinitroanisole (DNAN)

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

Salter-Blanc, Alexandra J.; Bylaska, Eric J.; Ritchie, Julia J.

2013-07-02

The environmental impacts of energetic compounds can be minimized through the design and selection of new energetic materials with favorable fate properties. Building predictive models to inform this process, however, is difficult because of uncertainties and complexities in some major fate-determining transformation reactions such as the alkaline hydrolysis of energetic nitroaromatic compounds (NACs). Prior work on the mechanisms of the reaction between NACs and OH– has yielded inconsistent results. In this study, the alkaline hydrolysis of 2,4,6-trinitrotoluene (TNT) and 2,4-dinitroanisole (DNAN) was investigated with coordinated experimental kinetic measurements and molecular modeling calculations. For TNT, the results suggest reversible formation ofmore » an initial product, which is likely either a Meisenheimer complex or a TNT anion formed by abstraction of a methyl proton by OH–. For DNAN, the results suggest that a Meisenheimer complex is an intermediate in the formation of 2,4-dinitrophenolate. Despite these advances, the remaining uncertainties in the mechanisms of these reactions—and potential variability between the hydrolysis mechanisms for different NACs—mean that it is not yet possible to generalize the results into predictive models (e.g., quantitative structure–activity relationships, QSARs) for hydrolysis of other NACs.« less

Mechanisms and kinetics of alkaline hydrolysis of the energetic nitroaromatic compounds 2,4,6-trinitrotoluene (TNT) and 2,4-dinitroanisole (DNAN).

PubMed

Salter-Blanc, Alexandra J; Bylaska, Eric J; Ritchie, Julia J; Tratnyek, Paul G

2013-07-02

The environmental impacts of energetic compounds can be minimized through the design and selection of new energetic materials with favorable fate properties. Building predictive models to inform this process, however, is difficult because of uncertainties and complexities in some major fate-determining transformation reactions such as the alkaline hydrolysis of energetic nitroaromatic compounds (NACs). Prior work on the mechanisms of the reaction between NACs and OH(-) has yielded inconsistent results. In this study, the alkaline hydrolysis of 2,4,6-trinitrotoluene (TNT) and 2,4-dinitroanisole (DNAN) was investigated with coordinated experimental kinetic measurements and molecular modeling calculations. For TNT, the results suggest reversible formation of an initial product, which is likely either a Meisenheimer complex or a TNT anion formed by abstraction of a methyl proton by OH(-). For DNAN, the results suggest that a Meisenheimer complex is an intermediate in the formation of 2,4-dinitrophenolate. Despite these advances, the remaining uncertainties in the mechanisms of these reactions-and potential variability between the hydrolysis mechanisms for different NACs-mean that it is not yet possible to generalize the results into predictive models (e.g., quantitative structure-activity relationships, QSARs) for hydrolysis of other NACs.

Shock Sensitivity of energetic materials

NASA Technical Reports Server (NTRS)

Kim, K.

1980-01-01

Viscoplastic deformation is examined as the principal source of hot energy. Some shock sensitivity data on a proposed model is explained. A hollow sphere model is used to approximate complex porous matrix of energetic materials. Two pieces of shock sensitivity data are qualitatively compared with results of the proposed model. The first is the p2 tau law. The second is the desensitization of energetic materials by a ramp wave applied stress. An approach to improve the model based on experimental observations is outlined.

DockingApp: a user friendly interface for facilitated docking simulations with AutoDock Vina.

PubMed

Di Muzio, Elena; Toti, Daniele; Polticelli, Fabio

2017-02-01

Molecular docking is a powerful technique that helps uncover the structural and energetic bases of the interaction between macromolecules and substrates, endogenous and exogenous ligands, and inhibitors. Moreover, this technique plays a pivotal role in accelerating the screening of large libraries of compounds for drug development purposes. The need to promote community-driven drug development efforts, especially as far as neglected diseases are concerned, calls for user-friendly tools to allow non-expert users to exploit the full potential of molecular docking. Along this path, here is described the implementation of DockingApp, a freely available, extremely user-friendly, platform-independent application for performing docking simulations and virtual screening tasks using AutoDock Vina. DockingApp sports an intuitive graphical user interface which greatly facilitates both the input phase and the analysis of the results, which can be visualized in graphical form using the embedded JMol applet. The application comes with the DrugBank set of more than 1400 ready-to-dock, FDA-approved drugs, to facilitate virtual screening and drug repurposing initiatives. Furthermore, other databases of compounds such as ZINC, available also in AutoDock format, can be readily and easily plugged in.

DockingApp: a user friendly interface for facilitated docking simulations with AutoDock Vina

NASA Astrophysics Data System (ADS)

Di Muzio, Elena; Toti, Daniele; Polticelli, Fabio

2017-02-01

Molecular docking is a powerful technique that helps uncover the structural and energetic bases of the interaction between macromolecules and substrates, endogenous and exogenous ligands, and inhibitors. Moreover, this technique plays a pivotal role in accelerating the screening of large libraries of compounds for drug development purposes. The need to promote community-driven drug development efforts, especially as far as neglected diseases are concerned, calls for user-friendly tools to allow non-expert users to exploit the full potential of molecular docking. Along this path, here is described the implementation of DockingApp, a freely available, extremely user-friendly, platform-independent application for performing docking simulations and virtual screening tasks using AutoDock Vina. DockingApp sports an intuitive graphical user interface which greatly facilitates both the input phase and the analysis of the results, which can be visualized in graphical form using the embedded JMol applet. The application comes with the DrugBank set of more than 1400 ready-to-dock, FDA-approved drugs, to facilitate virtual screening and drug repurposing initiatives. Furthermore, other databases of compounds such as ZINC, available also in AutoDock format, can be readily and easily plugged in.

Energetic Limitations on Microbial Respiration of Organic Compounds using Aqueous Fe(III) Complexes

NASA Astrophysics Data System (ADS)

Naughton, H.; Fendorf, S. E.

2015-12-01

Soil organic matter constitutes up to 75% of the terrestrial carbon stock. Microorganisms mediate the breakdown of organic compounds and the return of carbon to the atmosphere, predominantly through respiration. Microbial respiration requires an electron acceptor and an electron donor such as small fatty acids, organic acids, alcohols, sugars, and other molecules that differ in oxidation state of carbon. Carbon redox state affects how much energy is required to oxidize a molecule through respiration. Therefore, different organic compounds should offer a spectrum of energies to respiring microorganisms. However, microbial respiration has traditionally focused on the availability and reduction potential of electron acceptors, ignoring the organic electron donor. We found through incubation experiments that the organic compound serving as electron donor determined how rapidly Shewanella putrefaciens CN32 respires organic substrate and the extent of reduction of the electron acceptor. We simulated a range of energetically favorable to unfavorable electron acceptors using organic chelators bound to Fe(III) with equilibrium stability constants ranging from log(K) of 11.5 to 25.0 for the 1:1 complex, where more stable complexes are less favorable for microbial respiration. Organic substrates varied in nominal oxidation state of carbon from +2 to -2. The most energetically favorable substrate, lactate, promoted up to 30x more rapid increase in percent Fe(II) compared to less favorable substrates such as formate. This increased respiration on lactate was more substantial with less stable Fe(III)-chelate complexes. Intriguingly, this pattern contradicts respiration rate predicted by nominal oxidation state of carbon. Our results suggest that organic substrates will be consumed so long as the energetic toll corresponding to the electron donor half reaction is counterbalanced by the energy available from the electron accepting half reaction. We propose using the chemical structure of organic matter, elucidated with techniques such as FT-ICR MS, to improve microbial decomposition and carbon cycling models by incorporating energetic limitations due to carbon oxidation.

Energetic and flexibility properties captured by long molecular dynamics simulations of a membrane-embedded pMHCII-TCR complex.

PubMed

Bello, Martiniano; Correa-Basurto, José

2016-04-01

Although crystallographic data have provided important molecular insight into the interactions in the pMHC-TCR complex, the inherent features of this structural approach cause it to only provide a static picture of the interactions. While unbiased molecular dynamics simulations (UMDSs) have provided important information about the dynamic structural behavior of the pMHC-TCR complex, most of them have modeled the pMHC-TCR complex as soluble, when in physiological conditions, this complex is membrane bound; therefore, following this latter UMDS protocol might hamper important dynamic results. In this contribution, we performed three independent 300 ns-long UMDSs of the pMHCII-TCR complex anchored in two opposing membranes to explore the structural and energetic properties of the recognition of pMHCII by the TCR. The conformational ensemble generated through UMDSs was subjected to clustering and Cartesian principal component analyses (cPCA) to explore the dynamical behavior of the pMHCII-TCR association. Furthermore, based on the conformational population sampled through UMDSs, the effective binding free energy, per-residue free energy decomposition, and alanine scanning mutations were explored for the native pMHCII-TCR complex, as well as for 12 mutations (p1-p12MHCII-TCR) introduced in the native peptide. Clustering analyses and cPCA provide insight into the rocking motion of the TCR onto pMHCII, together with the presence of new electrostatic interactions not observed through crystallographic methods. Energetic results provide evidence of the main contributors to the pMHC-TCR complex formation as well as the key residues involved in this molecular recognition process.

Surface energetics and protein-protein interactions: analysis and mechanistic implications

PubMed Central

Peri, Claudio; Morra, Giulia; Colombo, Giorgio

2016-01-01

Understanding protein-protein interactions (PPI) at the molecular level is a fundamental task in the design of new drugs, the prediction of protein function and the clarification of the mechanisms of (dis)regulation of biochemical pathways. In this study, we use a novel computational approach to investigate the energetics of aminoacid networks located on the surface of proteins, isolated and in complex with their respective partners. Interestingly, the analysis of individual proteins identifies patches of surface residues that, when mapped on the structure of their respective complexes, reveal regions of residue-pair couplings that extend across the binding interfaces, forming continuous motifs. An enhanced effect is visible across the proteins of the dataset forming larger quaternary assemblies. The method indicates the presence of energetic signatures in the isolated proteins that are retained in the bound form, which we hypothesize to determine binding orientation upon complex formation. We propose our method, BLUEPRINT, as a complement to different approaches ranging from the ab-initio characterization of PPIs, to protein-protein docking algorithms, for the physico-chemical and functional investigation of protein-protein interactions. PMID:27050828

Nitrogen-rich salts of 5,5‧-bistetrazole-1,1‧-diolate: Syntheses, structures and properties

NASA Astrophysics Data System (ADS)

Yang, Ting; Zhang, Jian-Guo; Zhang, Zhi-Bin; Gozin, Michael

2018-03-01

A series of new nitrogen-rich energetic salts containing 1H,1‧H-[5,5‧-bitetrazole]-1,1‧-diol (BTO) anion and ethane-1,2-diaminium (1), 1-amino-1H-1,2,3-triazol-3-ium (2), 4-amino-4H-1,2,4-triazol-1-ium (3) and 4,5-diamino-4H-1,2,4-triazol-1-ium (4) cations were synthesized by direct salt formation or by metathesis strategy. The structures of energetic salts 1-4 were comprehensively characterized by elemental analysis, mass spectrometry, IR and NMR spectroscopies and by X-ray crystallography. DSC and TGA methods were used to study thermal properties of these salts. Additionally, the non-isothermal kinetic parameters and thermodynamic parameters were calculated by utilizing the Kissinger's and Ozawa-Doyle's methods. The enthalpies of formation for all target compounds in this study were calculated, and their sensitivity to mechanical impact and friction was tested according to BAM guidelines. We found these new energetic salts exhibit good thermal stability and have typical decomposition temperatures above 230 °C, except for the salt 2. All our salts have highly-positive enthalpies of formation (311.1-473.6 kJ mol-1) and are insensitive to impact and friction stimuli (>40 J, 120 N). With a high nitrogen-rich content, high enthalpy of formation, good thermostability and very low sensitivity to impact, some of these new salts may have a potential for application in the field of environmentally friendly insensitive energetic materials.

“Spatial Energetics”: Integrating Data From GPS, Accelerometry, and GIS to Address Obesity and Inactivity

PubMed Central

James, Peter; Jankowska, Marta; Marx, Christine; Hart, Jaime E.; Berrigan, David; Kerr, Jacqueline; Hurvitz, Philip M.; Hipp, J. Aaron; Laden, Francine

2016-01-01

To address the current obesity and inactivity epidemics, public health researchers have attempted to identify spatial factors that influence physical inactivity and obesity. Technologic and methodologic developments have led to a revolutionary ability to examine dynamic, high-resolution measures of temporally matched location and behavior data through GPS, accelerometry, and GIS. These advances allow the investigation of spatial energetics, high–spatiotemporal resolution data on location and time-matched energetics, to examine how environmental characteristics, space, and time are linked to activity-related health behaviors with far more robust and detailed data than in previous work. Although the transdisciplinary field of spatial energetics demonstrates promise to provide novel insights on how individuals and populations interact with their environment, there remain significant conceptual, technical, analytical, and ethical challenges stemming from the complex data streams that spatial energetics research generates. First, it is essential to better understand what spatial energetics data represent, the relevant spatial context of analysis for these data, and if spatial energetics can establish causality for development of spatially relevant interventions. Second, there are significant technical problems for analysis of voluminous and complex data that may require development of spatially aware scalable computational infrastructures. Third, the field must come to agreement on appropriate statistical methodologies to account for multiple observations per person. Finally, these challenges must be considered within the context of maintaining participant privacy and security. This article describes gaps in current practice and understanding, and suggests solutions to move this promising area of research forward. PMID:27528538

"Partying" hard: party style, motives for and effects of MDMA use at rave parties.

PubMed

M ter Bogt, Tom F; Engels, Rutger C M E

2005-01-01

This study examines motives for and consequences of MDMA use at different types of dance parties in the Netherlands (2001 and 2002). Participants were 490 visitors of three different types of rave parties, "club/mellow," "trance/mainstream," and "hardcore" (34% female, mean age 22.3 years, 76.5% MDMA users). Partygoers are motivated primarily by the energetic and euphoric effects they expect from MDMA. Quantity of MDMA use is associated with hardcore and trance/mainstream party style, with the motives of euphoria, sexiness, self-insight, and sociability/flirtatiousness (negative), and with gender, educational level (negative), and MDMA use by friends. Women report more (acute) negative effects--depression, confusion, loss of control, suspiciousness, edginess, nausea, dizziness--than men; and in particular, women who are motivated to cope with their problems by using MDMA are at risk. Men's polydrug use and notably their motivation to conform to friends by using MDMA are associated with negative effects.

Density functional theory calculations of biomolecules adsorption on phosphorene for biomedical applications

NASA Astrophysics Data System (ADS)

Rubio-Pereda, Pamela; H. Cocoletzi, Gregorio

2018-01-01

Recent experimental studies have found that phosphorene, the two-dimensional counterpart of black phosphorus, is more biological-friendly, in comparison with graphene, for the design of bio-integrated electronics based devices for biomedical applications. Following this research line, we theoretically investigate by first principle calculations, accounting for van der Waals effects, the interactions between phosphorene and typical amino acids (nonpolar, aromatic, positively charged and negatively charged). Testing different possible molecular orientations adsorption calculations have been done. Structural analysis, Löwdin electron population analysis and the study of the hydrophobic effect upon adsorption orientation were carried out in order to reveal the nature of the composite system interactions. Results show that amino acid molecules physisorb, mediated by an electron transfer process, on the phosphorene surface with a minimum disruption of their structure. Furthermore, the hydrophilic nature of phosphorene dictates the more energetically preferred adsorbed amino acid orientation. Ultimately, the nature of these interactions manifests the biological-friendly characteristic of phosphorene and its potential to be used as part of bioinorganic interfaces.

Performance and Aging of Mn/MnO2 as an Environmentally Friendly Energetic Time Delay Composition

DTIC Science & Technology

2014-04-16

for the powders used in these experiments are summarized in Table 1. Particle size distributions for Mn and MnO2 were obtained using a Malvern... particle size data. Mn/MnO2 compositions were dry mixed in 30 mL HDPE bottles using a Resodyn LabRAM mixer at 80% intensity in 2 min intervals for a...predicted. Due to the high heat losses of the small Table 1. Vendor Information of Reactant Powders powder nominal particle size vendor Bi2O3 15.4 μm Alfa

Evaluation of water displacement energetics in protein binding sites with grid cell theory.

PubMed

Gerogiokas, G; Southey, M W Y; Mazanetz, M P; Heifetz, A; Hefeitz, A; Bodkin, M; Law, R J; Michel, J

2015-04-07

Excess free energies, enthalpies and entropies of water in protein binding sites were computed via classical simulations and Grid Cell Theory (GCT) analyses for three pairs of congeneric ligands in complex with the proteins scytalone dehydratase, p38α MAP kinase and EGFR kinase respectively. Comparative analysis is of interest since the binding modes for each ligand pair differ in the displacement of one binding site water molecule, but significant variations in relative binding affinities are observed. Protocols that vary in their use of restraints on protein and ligand atoms were compared to determine the influence of protein-ligand flexibility on computed water structure and energetics, and to assess protocols for routine analyses of protein-ligand complexes. The GCT-derived binding affinities correctly reproduce experimental trends, but the magnitude of the predicted changes in binding affinities is exaggerated with respect to results from a previous Monte Carlo Free Energy Perturbation study. Breakdown of the GCT water free energies into enthalpic and entropic components indicates that enthalpy changes dominate the observed variations in energetics. In EGFR kinase GCT analyses revealed that replacement of a pyrimidine by a cyanopyridine perturbs water energetics up three hydration shells away from the ligand.

Water organization between oppositely charged surfaces: Implications for protein sliding along DNA a)

NASA Astrophysics Data System (ADS)

Marcovitz, Amir; Naftaly, Aviv; Levy, Yaakov

2015-02-01

Water molecules are abundant in protein-DNA interfaces, especially in their nonspecific complexes. In this study, we investigated the organization and energetics of the interfacial water by simplifying the geometries of the proteins and the DNA to represent them as two equally and oppositely charged planar surfaces immersed in water. We found that the potential of mean force for bringing the two parallel surfaces into close proximity comprises energetic barriers whose properties strongly depend on the charge density of the surfaces. We demonstrated how the organization of the water molecules into discretized layers and the corresponding energetic barriers to dehydration can be modulated by the charge density on the surfaces, salt, and the structure of the surfaces. The 1-2 layers of ordered water are tightly bound to the charged surfaces representing the nonspecific protein-DNA complex. This suggests that water might mediate one-dimensional diffusion of proteins along DNA (sliding) by screening attractive electrostatic interactions between the positively charged molecular surface on the protein and the negatively charged DNA backbone and, in doing so, reduce intermolecular friction in a manner that smoothens the energetic landscape for sliding, and facilitates the 1D diffusion of the protein.

Dietary nitrate increases arginine availability and protects mitochondrial complex I and energetics in the hypoxic rat heart

PubMed Central

Ashmore, Tom; Fernandez, Bernadette O; Branco-Price, Cristina; West, James A; Cowburn, Andrew S; Heather, Lisa C; Griffin, Julian L; Johnson, Randall S; Feelisch, Martin; Murray, Andrew J

2014-01-01

Hypoxic exposure is associated with impaired cardiac energetics in humans and altered mitochondrial function, with suppressed complex I-supported respiration, in rat heart. This response might limit reactive oxygen species generation, but at the cost of impaired electron transport chain (ETC) activity. Dietary nitrate supplementation improves mitochondrial efficiency and can promote tissue oxygenation by enhancing blood flow. We therefore hypothesised that ETC dysfunction, impaired energetics and oxidative damage in the hearts of rats exposed to chronic hypoxia could be alleviated by sustained administration of a moderate dose of dietary nitrate. Male Wistar rats (n = 40) were given water supplemented with 0.7 mmol l−1 NaCl (as control) or 0.7 mmol l−1 NaNO3, elevating plasma nitrate levels by 80%, and were exposed to 13% O2 (hypoxia) or normoxia (n = 10 per group) for 14 days. Respiration rates, ETC protein levels, mitochondrial density, ATP content and protein carbonylation were measured in cardiac muscle. Complex I respiration rates and protein levels were 33% lower in hypoxic/NaCl rats compared with normoxic/NaCl controls. Protein carbonylation was 65% higher in hearts of hypoxic rats compared with controls, indicating increased oxidative stress, whilst ATP levels were 62% lower. Respiration rates, complex I protein and activity, protein carbonylation and ATP levels were all fully protected in the hearts of nitrate-supplemented hypoxic rats. Both in normoxia and hypoxia, dietary nitrate suppressed cardiac arginase expression and activity and markedly elevated cardiac l-arginine concentrations, unmasking a novel mechanism of action by which nitrate enhances tissue NO bioavailability. Dietary nitrate therefore alleviates metabolic abnormalities in the hypoxic heart, improving myocardial energetics. PMID:25172947

Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H–SiC

NASA Astrophysics Data System (ADS)

Igumbor, E.; Olaniyan, O.; Mapasha, R. E.; Danga, H. T.; Omotoso, E.; Meyer, W. E.

2018-05-01

Electrically active induced energy levels in semiconductor devices could be beneficial to the discovery of an enhanced p or n-type semiconductor. Nitrogen (N) implanted into 4H–SiC is a high energy process that produced high defect concentrations which could be removed during dopant activation annealing. On the other hand, boron (B) substituted for silicon in SiC causes a reduction in the number of defects. This scenario leads to a decrease in the dielectric properties and induced deep donor and shallow acceptor levels. Complexes formed by the N, such as the nitrogen-vacancy centre, have been reported to play a significant role in the application of quantum bits. In this paper, results of charge states thermodynamic transition level of the N and B vacancy-complexes in 4H–SiC are presented. We explore complexes where substitutional N/N or B/B sits near a Si (V) or C (V) vacancy to form vacancy-complexes (NV, NV, NV, NV, BV, BV, BV and BV). The energies of formation of the N related vacancy-complexes showed the NV to be energetically stable close to the valence band maximum in its double positive charge state. The NV is more energetically stable in the double negative charge state close to the conduction band minimum. The NV on the other hand, induced double donor level and the NV induced a double acceptor level. For B related complexes, the BV and BV were energetically stable in their single positive charge state close to the valence band maximum. As the Fermi energy is varied across the band gap, the neutral and single negative charge states of the BV become more stable at different energy levels. B and N related complexes exhibited charge state controlled metastability behaviour.

Long-lasting injection of solar energetic electrons into the heliosphere

NASA Astrophysics Data System (ADS)

Dresing, N.; Gómez-Herrero, R.; Heber, B.; Klassen, A.; Temmer, M.; Veronig, A.

2018-05-01

Context. The main sources of solar energetic particle (SEP) events are solar flares and shocks driven by coronal mass ejections (CMEs). While it is generally accepted that energetic protons can be accelerated by shocks, whether or not these shocks can also efficiently accelerate solar energetic electrons is still debated. In this study we present observations of the extremely widespread SEP event of 26 Dec 2013 To the knowledge of the authors, this is the widest longitudinal SEP distribution ever observed together with unusually long-lasting energetic electron anisotropies at all observer positions. Further striking features of the event are long-lasting SEP intensity increases, two distinct SEP components with the second component mainly consisting of high-energy particles, a complex associated coronal activity including a pronounced signature of a shock in radio type-II observations, and the interaction of two CMEs early in the event. Aims: The observations require a prolonged injection scenario not only for protons but also for electrons. We therefore analyze the data comprehensively to characterize the possible role of the shock for the electron event. Methods: Remote-sensing observations of the complex solar activity are combined with in situ measurements of the particle event. We also apply a graduated cylindrical shell (GCS) model to the coronagraph observations of the two associated CMEs to analyze their interaction. Results: We find that the shock alone is likely not responsible for this extremely wide SEP event. Therefore we propose a scenario of trapped energetic particles inside the CME-CME interaction region which undergo further acceleration due to the shock propagating through this region, stochastic acceleration, or ongoing reconnection processes inside the interaction region. The origin of the second component of the SEP event is likely caused by a sudden opening of the particle trap.

Methodological approach to simulation and choice of ecologically efficient and energetically economic wind turbines (WT)

NASA Astrophysics Data System (ADS)

Bespalov, Vadim; Udina, Natalya; Samarskaya, Natalya

2017-10-01

Use of wind energy is related to one of the prospective directions among renewed energy sources. A methodological approach is reviewed in the article to simulation and choice of ecologically efficient and energetically economic wind turbines on the designing stage taking into account characteristics of natural-territorial complex and peculiarities of anthropogenic load in the territory of WT location.

Computational Chemistry Toolkit for Energetic Materials Design

DTIC Science & Technology

2006-11-01

industry are aggressively engaged in efforts to develop multiscale modeling and simulation methodologies to model and analyze complex phenomena across...energetic materials design. It is hoped that this toolkit will evolve into a collection of well-integrated multiscale modeling methodologies...Experimenta Theoreticala This Work 1-5-Diamino-4- methyl- tetrazolium nitrate 8.4 41.7 47.5 1-5-Diamino-4- methyl- tetrazolium azide 138.1 161.6

Intrinsic Thermodynamics and Structure Correlation of Benzenesulfonamides with a Pyrimidine Moiety Binding to Carbonic Anhydrases I, II, VII, XII, and XIII

PubMed Central

Kišonaitė, Miglė; Zubrienė, Asta; Čapkauskaitė, Edita; Smirnov, Alexey; Smirnovienė, Joana; Kairys, Visvaldas; Michailovienė, Vilma; Manakova, Elena; Gražulis, Saulius; Matulis, Daumantas

2014-01-01

The early stage of drug discovery is often based on selecting the highest affinity lead compound. To this end the structural and energetic characterization of the binding reaction is important. The binding energetics can be resolved into enthalpic and entropic contributions to the binding Gibbs free energy. Most compound binding reactions are coupled to the absorption or release of protons by the protein or the compound. A distinction between the observed and intrinsic parameters of the binding energetics requires the dissection of the protonation/deprotonation processes. Since only the intrinsic parameters can be correlated with molecular structural perturbations associated with complex formation, it is these parameters that are required for rational drug design. Carbonic anhydrase (CA) isoforms are important therapeutic targets to treat a range of disorders including glaucoma, obesity, epilepsy, and cancer. For effective treatment isoform-specific inhibitors are needed. In this work we investigated the binding and protonation energetics of sixteen [(2-pyrimidinylthio)acetyl]benzenesulfonamide CA inhibitors using isothermal titration calorimetry and fluorescent thermal shift assay. The compounds were built by combining four sulfonamide headgroups with four tailgroups yielding 16 compounds. Their intrinsic binding thermodynamics showed the limitations of the functional group energetic additivity approach used in fragment-based drug design, especially at the level of enthalpies and entropies of binding. Combined with high resolution crystal structural data correlations were drawn between the chemical functional groups on selected inhibitors and intrinsic thermodynamic parameters of CA-inhibitor complex formation. PMID:25493428

Adult family relationships in the context of friendship

PubMed Central

Fuller-Iglesias, Heather R.; Webster, Noah; Antonucci, Toni C.

2013-01-01

The present study examined the complex way in which relationships with family and friends shape health and well-being in adulthood over time. Specifically, we explored whether the longitudinal effects of positive and negative family relationship quality on health and well-being differ in the context of varying levels of positive friend relationships. Data were from two waves (1992/1993 and 2005) of the Social Relations, Aging and Health Study. The sample included respondents aged 18 and older at Wave 1 who reported having a best friend at both waves (N = 455), and consisted of 291 (64%) women and 164 (36%) men. Wave 1 friend positivity and family positivity interacted to predict self-rated health but not self-esteem, indicating that among respondents with a less positive friend relationship, more positive family relationships were related to worse health at Wave 2. Wave 1 friend positivity and family negativity significantly interacted to predict self-rated health and self-esteem at Wave 2. The nature of the interactions were consistent in that among respondents with a more highly positive friend relationship, less negative family relationships were linked to better health and self-esteem at Wave 2. Findings provide insight into the complex way in which social relations impact positive outcomes in adulthood. Previous studies have documented the consistent and straightforward manner in which negative relationships impact health and well-being, whereas this study illustrates that the role of positive social relations is more variable and dependent on multiple relationship contexts. PMID:24273462

A perspective on modeling the multiscale response of energetic materials

NASA Astrophysics Data System (ADS)

Rice, Betsy M.

2017-01-01

The response of an energetic material to insult is perhaps one of the most difficult processes to model due to concurrent chemical and physical phenomena occurring over scales ranging from atomistic to continuum. Unraveling the interdependencies of these complex processes across the scales through modeling can only be done within a multiscale framework. In this paper, I will describe progress in the development of a predictive, experimentally validated multiscale reactive modeling capability for energetic materials at the Army Research Laboratory. I will also describe new challenges and research opportunities that have arisen in the course of our development which should be pursued in the future.

Flight responses by a migratory soaring raptor to changing meteorological conditions.

PubMed

Lanzone, Michael J; Miller, Tricia A; Turk, Philip; Brandes, David; Halverson, Casey; Maisonneuve, Charles; Tremblay, Junior; Cooper, Jeff; O'Malley, Kieran; Brooks, Robert P; Katzner, Todd

2012-10-23

Soaring birds that undertake long-distance migration should develop strategies to minimize the energetic costs of endurance flight. This is relevant because condition upon completion of migration has direct consequences for fecundity, fitness and thus, demography. Therefore, strong evolutionary pressures are expected for energy minimization tactics linked to weather and topography. Importantly, the minute-by-minute mechanisms birds use to subsidize migration in variable weather are largely unknown, in large part because of the technological limitations in studying detailed long-distance bird flight. Here, we show golden eagle (Aquila chrysaetos) migratory response to changing meteorological conditions as monitored by high-resolution telemetry. In contrast to expectations, responses to meteorological variability were stereotyped across the 10 individuals studied. Eagles reacted to increased wind speed by using more orographic lift and less thermal lift. Concomitantly, as use of thermals decreased, variation in flight speed and altitude also decreased. These results demonstrate how soaring migrant birds can minimize energetic expenditures, they show the context for avian decisions and choices of specific instantaneous flight mechanisms and they have important implications for design of bird-friendly wind energy.

Fish: A New Computer Program for Friendly Introductory Statistics Help

ERIC Educational Resources Information Center

Brooks, Gordon P.; Raffle, Holly

2005-01-01

All introductory statistics students must master certain basic descriptive statistics, including means, standard deviations and correlations. Students must also gain insight into such complex concepts as the central limit theorem and standard error. This article introduces and describes the Friendly Introductory Statistics Help (FISH) computer…

[Energetics of complex formation of the DNA hairpin structure d(GCGAAGC) with aromatic ligands].

PubMed

Kostiukov, V V

2011-01-01

The energy contributions of various physical interactions to the total Gibbs energy of complex formation of the biologically important DNA hairpin d(GCGAAGC) with aromatic antitumor antibiotics daunomycin and novantron and the mutagens ethidium and proflavine have been calculated. It has been shown that the relatively small value of the total energy of binding of the ligands to the hairpin is the sum of components great in absolute value and different in sign. The contributions of van der Waals interactions and both intra- and intermolecular hydrogen bonds and bonds with aqueous environment have been studied. According to the calculations, the hydrophobic and van der Waals components are energetically favorable in complex formation of the ligands with the DNA pairpin d(GCGAAGC), whereas the electrostatic (with consideration of hydrogen bonds) and entropic components are unfavorable.

Doctoral Assistants = Critical Friends: A Simple yet Complex Equation

ERIC Educational Resources Information Center

Hay, John; Laguerre, Fabrice; Moore, Eric; Reedy, Katherine; Rose, Scott; Vickers, Jerome

2015-01-01

The Carnegie Project on the Education Doctorate (CPED) encourages doctoral candidates volunteering in order to give back and continue their relationship with the university after completing their dissertation. Volunteering can take on many forms, from acting as doctoral assistants to performing the role of critical friends on future doctoral…

Energetic Processing of Interstellar Ices: A Route to Complexity

NASA Technical Reports Server (NTRS)

Moore, Marla H.; Hudson, Reggie L.

2009-01-01

More than 140 gas-phase molecules have been detected in the interstellar (IS) medium or in circumstellar environments including inorganics, organics, ions, and radicals. The significant abundance of large, complex organic molecules, and families of isomers in these regions makes the origin and formation history of these species the subject of debate. Observationally determined condensed-phase species are H2O, CO, CO2, NH3 and CH30H, with CH4, HCOOH, OCS, OCN-, H2CO and NH4(+) present at trace levels. These ices can undergo energetic processing with cosmic rays or far-UV photons to form larger complex organics with abundance levels that make them undetectable in icy mantles. Once warmed, however, it is likely that these complex species would enter the gas-phase where they might be detected by Herschel or Alma. Understanding the role of radiation chemistry and thermal processing of ices and identifying new products are the goals of our laboratory research. In the Cosmic lee Laboratory at NASA Goddard Space Plight Center, we can study both the photo-and radiation chemistries of ices from 8 -- 300 K. Using dear- and mid-IR spectroscopy we can follow the destruction of primary molecules and the formation of radicals and secondary products as a function of energetic processing. During warming we can monitor the trapping of species and the results of any thermal chemistry. An overview of recent and past work will focus on complex secondary radiation products from small condensed-phase IS species. Likely reactions include dimerization, isomerization, H-addition and H-elimination. Another focus of our work is the development of reaction schemes for the formation of complex molecules and the use of such schemes to predict new molecules awaiting detection by Herschel and Alma.

C-PCM based calculation of energy profiles for proton transfer in phosphorus-containing acid- N, N-dimethylformamide complexes

NASA Astrophysics Data System (ADS)

Fedorova, I. V.; Khatuntseva, E. A.; Krest'yaninov, M. A.; Safonova, L. P.

2016-02-01

Proton transfer along the hydrogen bond in complexes of DMF with H3PO4, H3PO3, CH3H2PO3, and their dimers has been investigated by the B3LYP/6-31++G** method in combination with the C-PCM model. When the Oacid···ODMF distance ( R) in the scanning procedure is not fixed, the energy profile in all cases has a single well. When this distance is fixed, there can be a proton transfer in all of the complexes in the gas phase at R > 2.6 Å; if solvation is taken into account, proton transfer can take place at R > 2.4 Å ( R > 2.5 Å for DMF complexes with CH3H2PO3 and its dimer). The height of the energy barrier to proton transfer increases with increasing R. Proton transfer is energetically most favorable in the DMF-phosphoric acid complexes. The structural and energetic characteristics of the hydrogen-bonded complexes calculated on the basis of the solvation model are compared with the same parameters for the complexes in the gas phase.

Three Dimensional Energetics of Left Ventricle Flows Using Time-Resolved DPIV

NASA Astrophysics Data System (ADS)

Pierrakos, Olga; Vlachos, Pavlos

2006-11-01

Left ventricular (LV) flows in the human heart are very complex and in the presence of unhealthy or prosthetic heart valves (HV), the complexity of the flow is further increased. Yet to date, no study has documented the complex 3D hemodynamic characteristics and energetics of LV flows. We present high sampling frequency Time Resolved DPIV results obtained in a flexible, transparent LV documenting the evolution of eddies and turbulence. The purpose is to characterize the energetics of the LV flow field in the presence of four orientations of the most commonly implanted mechanical bileaflet HV and a porcine valve. By decomposing the energy scales of the flow field, the ultimate goal is to quantify the total energy losses associated with vortex ring formation and turbulence dissipation. The energies associated to vortex ring formation give a measure of the energy trapped within the structure while estimations of the turbulence dissipation rate (TDR) give a measure of the energy dissipated at the smaller scales. For the first time in cardiovascular applications, an LES-based PIV method, which overcomes the limitations of conventional TDR estimation methods that assume homogeneous isotropic turbulence, was employed. We observed that energy lost at the larger scales (vortex ring) is much higher than the energy lost at the smaller scales due to turbulence dissipation.

Plasma wave interactions with energetic ions near the magnetic equator

NASA Technical Reports Server (NTRS)

Gurnett, D. A.

1975-01-01

An intense band of electromagnetic noise is frequently observed near the magnetic equatorial plane at radial distance from about 2 to 5 Re. Recent wideband wave-form measurements with the IMP-6 and Hawkeye-1 satellites have shown that the equatorial noise consists of a complex superposition of many harmonically spaced lines. Several distinctly different frequency spacings are often evident in the same spectrum. The frequency spacing typically ranges from a few Hz to a few tens of Hz. It is suggested that these waves are interacting with energetic protons, alpha particles, and other heavy ions trapped near the magnetic equator. The possible role these waves play in controlling the distribution of the energetic ions is considered.

SmartHome: a domotic framework based on smart sensing and actuator network to reduce energy wastes

NASA Astrophysics Data System (ADS)

Santamaria, Amilcare Francesco; De Rango, Floriano; Falbo, Domenico; Barletta, Domenico

2014-05-01

Domestic environment and human interaction with services supplied by domotic devices is going to be a very interesting application field. With a domotic system is possible to achieve great interaction between human beings, environments and smart devices. The enhancing of these interactions is the main goal of this work whose intent is to improve the classic concept of domotics. The framework we developed can be used for several application fields such as lighting, heating, conditioning or water management and energy consumption. In particular, the proposed system can optimize energy consumptions by rising awareness to users that have full control of their house and the possibility to save money and reduce the impact of the energetic consumes to the earth, matching the new "green" motto requirements. In this way, the overall system wants to match the central concept of Internet Of Things (IoT) as well. From this point of view a complex automation system with smart devices make possible a more efficient way to produce, follow and manage domotic policies. Following the spread of IoT, for this work we designed and implemented new plug-and-play and ready-to-use smart devices that are part of a complex automation system that offers a user-friendly web application and allows users to control and interact with different plans of their house in order to make life more comfortable and be aware of their energy consumptions. Control and awareness arc the two key points that led us to develop the proposed system.

Froude space: An aquatic currency derived from remote sensing data for assessing ecological potential of river floodplains

NASA Astrophysics Data System (ADS)

Lorang, M. S.; Stanford, J.; Steele, B.

2009-12-01

In this research we take a systems ecology approach to the evaluation of river floodplains by ranking them according to their energetic complexity at or near base flow conditions. The underlying hypothesis is that energetic complexity equates to a higher potential for sustaining maximum biological diversity, in particular as it relates to Salmonids. Fr number is a hydraulic index of relative specific energy in a flowing water column ranging from calm, no flow conditions where Fr = 0 to 0.8 at the onset of rapids and higher values approaching 1 or > at locations of breaking waves and hydraulic jumps. Most of the water flowing in a gravel-bed river exists in the transition range of Fr = 0.1 to 0.8, creating a complex array of potential hydrologic habitat commonly described through observation as riffles, runs, pools eddies, and so on. We use 1.6 m2 resolution multispectral satellite imagery to predict and map water depth (h), mean flow velocity (V) and Froude number (Fr=V/(gh)^0.5) by using a distribution-free statistical learner and error analysis approach. This approach links measures of V and h made from a raft deploying an acoustic Doppler profiler (ADP) and GPS with the reflectance characteristics from the satellite imagery (4 bands) that correspond to each ADP profile. This analysis of Fr space in combination with independent classification of depth and velocity provides physical metrics related to the energetic state of flow in the river at the time of image acquisition. We use these metrics, determined from a suite of 23 floodplains spread across the rim of the North Pacific (including British Columbia, Alaska and the Kamchatka Peninsula of Russia) and covering the range in fluvial geomorphic type from braided to meandering, to rank them in terms of energetic complexity.

Bioenergetic Constraints on the Evolution of Complex Life

PubMed Central

Lane, Nick

2014-01-01

All morphologically complex life on Earth, beyond the level of cyanobacteria, is eukaryotic. All eukaryotes share a common ancestor that was already a complex cell. Despite their biochemical virtuosity, prokaryotes show little tendency to evolve eukaryotic traits or large genomes. Here I argue that prokaryotes are constrained by their membrane bioenergetics, for fundamental reasons relating to the origin of life. Eukaryotes arose in a rare endosymbiosis between two prokaryotes, which broke the energetic constraints on prokaryotes and gave rise to mitochondria. Loss of almost all mitochondrial genes produced an extreme genomic asymmetry, in which tiny mitochondrial genomes support, energetically, a massive nuclear genome, giving eukaryotes three to five orders of magnitude more energy per gene than prokaryotes. The requirement for endosymbiosis radically altered selection on eukaryotes, potentially explaining the evolution of unique traits, including the nucleus, sex, two sexes, speciation, and aging. PMID:24789818

Density functional studies of the defect-induced electronic structure modifications in bilayer boronitrene

NASA Astrophysics Data System (ADS)

Ukpong, A. M.; Chetty, N.

2012-05-01

The van der Waals interaction-corrected density functional theory is used in this study to investigate the formation, energetic stability, and inter-layer cohesion in bilayer hexagonal boronitrene. The effect of inter-layer separation on the electronic structure is systematically investigated. The formation and energetic stability of intrinsic defects are also investigated at the equilibrium inter-layer separation. It is found that nonstoichiometric defects, and their complexes, that induce excess nitrogen or excess boron, in each case, are relatively more stable in the atmosphere that corresponds to the excess atomic species. The modifications of the electronic structure due to formation of complexes are also investigated. It is shown that van der Waals density functional theory gives an improved description of the cohesive properties but not the electronic structure in bilayer boronitrene compared to other functionals. We identify energetically favourable topological defects that retain the energy gap in the electronic structure, and discuss their implications for band gap engineering in low-n layer boronitrene insulators. The relative strengths and weaknesses of the functionals in predicting the properties of bilayer boronitrene are also discussed.

"Maybe They Don't Even Know That I Exist": Challenges Faced by Family Members and Friends of Patients with Advanced Kidney Disease.

PubMed

O'Hare, Ann M; Szarka, Jackie; McFarland, Lynne V; Vig, Elizabeth K; Sudore, Rebecca L; Crowley, Susan; Reinke, Lynn F; Trivedi, Ranak; Taylor, Janelle S

2017-06-07

Family members and friends of patients with advanced chronic illness are increasingly called on to assist with ever more complex medical care and treatment decisions arising late in the course of illness. Our goal was to learn about the experiences of family members and friends of patients with advanced kidney disease. As part of a study intended to identify opportunities to enhance advance care planning, we conducted semistructured interviews at the Veterans Affairs Puget Sound Health Care System with 17 family members and friends of patients with advanced kidney disease. Interviews were conducted between April of 2014 and May of 2016 and were audiotaped, transcribed, and analyzed inductively using grounded theory to identify emergent themes. The following three themes emerged from interviews with patients' family members and friends: ( 1 ) their roles in care and planning were fluid over the course of the patient's illness, shaped by the patients' changing needs and their readiness to involve those close to them; ( 2 ) their involvement in patients' care was strongly shaped by health care system needs. Family and friends described filling gaps left by the health care system and how their involvement in care and decision-making was at times constrained and at other times expected by providers, depending on system needs; and ( 3 ) they described multiple sources of tension and conflict in their interactions with patients and the health care system, including instances of being pitted against the patient. Interviews with family members and friends of patients with advanced kidney disease provide a window on the complex dynamics shaping their engagement in patients' care, and highlight the potential value of offering opportunities for engagement throughout the course of illness. Copyright © 2017 by the American Society of Nephrology.

Energetic neutral atom emissions from Titan interaction with Saturn's magnetosphere.

PubMed

Mitchell, D G; Brandt, P C; Roelof, E C; Dandouras, J; Krimigis, S M; Mauk, B H

2005-05-13

The Cassini Magnetospheric Imaging Instrument (MIMI) observed the interaction of Saturn's largest moon, Titan, with Saturn's magnetosphere during two close flybys of Titan on 26 October and 13 December 2004. The MIMI Ion and Neutral Camera (INCA) continuously imaged the energetic neutral atoms (ENAs) generated by charge exchange reactions between the energetic, singly ionized trapped magnetospheric ions and the outer atmosphere, or exosphere, of Titan. The images reveal a halo of variable ENA emission about Titan's nearly collisionless outer atmosphere that fades at larger distances as the exospheric density decays exponentially. The altitude of the emissions varies, and they are not symmetrical about the moon, reflecting the complexity of the interactions between Titan's upper atmosphere and Saturn's space environment.

The Dark Side of Friendship: Questions about Negative Interactions between Friends.

ERIC Educational Resources Information Center

Berndt, Thomas J.

Alluding to the difficulty in explaining the two opposing powers, the "dark side" and the Force, in the Star Wars movies, this paper focuses on the complex combination of negative and positive interactions among children who are best friends. Presented in question-answer format, the paper discusses research findings and needs related to…

STS-91: Flight Crew Meets with Family and Friends at Launch Complex 39A

NASA Technical Reports Server (NTRS)

1998-01-01

The crew (Commander Charles J. Precourt, Pilot Dominic L. Pudwill Gorie, Mission Specialists Wendy B. Lawrence, Franklin R. Chang-Diaz, Janet L. Kavandi and Valery Victorovitch Ryumin) take time from their busy schedule to chat with friends and family, at a distance. They also pose for group and single pictures.

Energetic Materials Effects on Essential Soil Processes: Decomposition of Orchard Grass (Dactylis glomerata) Litter in Soil Contaminated with Energetic Materials

DTIC Science & Technology

2014-02-01

moisture level of 14% dry soil mass was maintained for the duration of the study by weekly additions of ASTM Type I water. Soil samples were collected...maintain the initial soil moisture level. One cluster of Orchard grass straw was harvested from a set of randomly selected replicate containers...decomposition is among the most integrating processes within the soil ecosystem because it involves complex interactions of soil microbial, plant , and

[Dietary interventions and social care for treating obesity in children].

PubMed

Wiegand, S; Bau, A-M; Babitsch, B

2011-05-01

The prevalence of obesity and associated comorbidities among children and adolescents has risen worldwide throughout the past 3 decades. To break this trend, population-based activities in health promotion/prevention and health care are necessary. Studies showed that long-term eating behavior improvement with the cooperation of the patient's family together with child-friendly organization support both individual therapeutic improvements as well as a relevant reduction of obesity prevalence. A significant BMI reduction can be achieved with a normal varied diet, whose energetic value is 300-400 kcal/day below the patient's daily energetic needs, due to the lower consumption of fat and sugar. This requires, however, that the entire family be willing to change their unhealthy eating behaviors (e.g., soft drinks and fast food) and to introduce regular meals into their daily routine. Sensibly, most therapies combine diet therapy with increased physical activity and parental training. Controlled media consumption, active leisure-time behavior, and a structured daily routine are further conditions for successful weight reduction. The high-risk groups for pediatric obesity, i.e., families with migration background and/or low socioeconomic status, have been poorly reached by established programs.

Alkali and alkaline earth metal salts of tetrazolone: structurally interesting and excellently thermostable.

PubMed

He, Piao; Wu, Le; Wu, Jin-Ting; Yin, Xin; Gozin, Michael; Zhang, Jian-Guo

2017-07-04

Tetrazolone (5-oxotetrazole) was synthesized by a moderate strategy through three steps (addition, cyclization and catalytic hydrogenation) avoiding the unstable intermediate diazonium, as reported during the previous preparation. Alkali and alkaline earth metal salts with lithium (1), sodium (2), potassium (3), rubidium (4) caesium (5), magnesium (6), calcium (7), strontium (8) and barium (9) were prepared and fully characterized using elemental analysis, IR and NMR spectroscopy, DSC and TG analysis. All metal salts were characterized via single-crystal X-ray diffraction. They crystallize in common space groups with high densities ranging from 1.479 (1) to 3.060 g cm -3 (5). Furthermore, the crystal structures of 7, 8 and 9 reveal interesting porous energetic coordination polymers with strong hydrogen bond interactions. All new salts have good thermal stabilities with decomposition temperature between 215.0 °C (4) and 328.2 °C (7), significantly higher than that of the reported nitrogen-rich salt neutral tetrazolone. The sensitivities towards impact and friction were tested using standard methods, and all the tetrazolone-based compounds investigated can be classified into insensitive. The flame test of these metal salts supports their potential use as perchlorate-free pyrotechnics or eco-friendly insensitive energetic materials.

Friendship in High-functioning Children with Autism Spectrum Disorder: Mixed and Non-mixed Dyads

PubMed Central

Solomon, Marjorie; Aviezer, Anat; Heung, Kelly; Brown, John; Rogers, Sally J.

2017-01-01

Friendships containing a child with autism and a friend with typical development (“mixed” friendships, n = 26) and those of children with autism and a friend with a disability (“non-mixed,” n = 16) were contrasted with friendships of typically developing subjects and their friends (n = 31). Measures included dyadic interaction samples, and interview and questionnaire data from subjects, friends, and parents. Mixed friendship interactions resembled typical friendships. Participants in mixed friendships were more responsive to one another, had stronger receptive language skills, exhibited greater positive social orientation and cohesion, and demonstrated more complex coordinated play than in the non-mixed dyads. Exposure to typical peers appears to have significant effects on friendship behaviors. PMID:18058212

Gesture in Multiparty Interaction: A Study of Embodied Discourse in Spoken English and American Sign Language

ERIC Educational Resources Information Center

Shaw, Emily P.

2013-01-01

This dissertation is an examination of gesture in two game nights: one in spoken English between four hearing friends and another in American Sign Language between four Deaf friends. Analyses of gesture have shown there exists a complex integration of manual gestures with speech. Analyses of sign language have implicated the body as a medium…

Effective concentration as a tool for quantitatively addressing preorganization in multicomponent assemblies: application to the selective complexation of lanthanide cations.

PubMed

Canard, Gabriel; Koeller, Sylvain; Bernardinelli, Gérald; Piguet, Claude

2008-01-23

The beneficial entropic effect, which may be expected from the connection of three tridentate binding units to a strain-free covalent tripod for complexing nine-coordinate cations (Mz+ = Ca2+, La3+, Eu3+, Lu3+), is quantitatively analyzed by using a simple thermodynamic additive model. The switch from pure intermolecular binding processes, characterizing the formation of the triple-helical complexes [M(L2)3]z+, to a combination of inter- and intramolecular complexation events in [M(L8)]z+ shows that the ideal structural fit observed in [M(L8)]z+ indeed masks large energetic constraints. This limitation is evidenced by the faint effective concentrations, ceff, which control the intramolecular ring-closing reactions operating in [M(L8)]z+. This predominence of the thermodynamic approach over the usual structural analysis agrees with the hierarchical relationships linking energetics and structures. Its simple estimation by using a single microscopic parameter, ceff, opens novel perspectives for the molecular tuning of specific receptors for the recognition of large cations, a crucial point for the programming of heterometallic f-f complexes under thermodynamic control.

Binding Thermodynamics of Ferredoxin:NADP+ Reductase: Two Different Protein Substrates and One Energetics

PubMed Central

Martínez-Júlvez, Marta; Medina, Milagros; Velázquez-Campoy, Adrián

2009-01-01

Abstract The thermodynamics of the formation of binary and ternary complexes between Anabaena PCC 7119 FNR and its substrates, NADP+ and Fd, or Fld, has been studied by ITC. Despite structural dissimilarities, the main difference between Fd and Fld binding to FNR relates to hydrophobicity, reflected in different binding heat capacity and number of water molecules released from the interface. At pH 8, the formation of the binary complexes is both enthalpically and entropically driven, accompanied by the protonation of at least one ionizable group. His299 FNR has been identified as the main responsible for the proton exchange observed. However, at pH 10, where no protonation occurs and intrinsic binding parameters can be obtained, the formation of the binary complexes is entropically driven, with negligible enthalpic contribution. Absence of the FMN cofactor in Fld does not alter significantly the strength of the interaction, but considerably modifies the enthalpic and entropic contributions, suggesting a different binding mode. Ternary complexes show negative cooperativity (6-fold and 11-fold reduction in binding affinity, respectively), and an increase in the enthalpic contribution (more favorable) and a decrease in the entropic contribution (less favorable), with regard to the binary complexes energetics. PMID:19527656

New insights into hydrosilylation of unsaturated carbon-heteroatom (C═O, C═N) bonds by rhenium(V)-dioxo complexes.

PubMed

Huang, Liangfang; Wang, Wenmin; Wei, Xiaoqin; Wei, Haiyan

2015-04-23

The hydrosilylation of unsaturated carbon-heteroatom (C═O, C═N) bonds catalyzed by high-valent rhenium(V)-dioxo complex ReO2I(PPh3)2 (1) were studied computationally to determine the underlying mechanism. Our calculations revealed that the ionic outer-sphere pathway in which the organic substrate attacks the Si center in an η(1)-silane rhenium adduct to prompt the heterolytic cleavage of the Si-H bond is the most energetically favorable process for rhenium(V)-dioxo complex 1 catalyzed hydrosilylation of imines. The activation energy of the turnover-limiting step was calculated to be 22.8 kcal/mol with phenylmethanimine. This value is energetically more favorable than the [2 + 2] addition pathway by as much as 10.0 kcal/mol. Moreover, the ionic outer-sphere pathway competes with the [2 + 2] addition mechanism for rhenium(V)-dioxo complex 1 catalyzing the hydrosilylation of carbonyl compounds. Furthermore, the electron-donating group on the organic substrates would induce a better activity favoring the ionic outer-sphere mechanistic pathway. These findings highlight the unique features of high-valent transition-metal complexes as Lewis acids in activating the Si-H bond and catalyzing the reduction reactions.

Design and analysis of forward and reverse models for predicting defect accumulation, defect energetics, and irradiation conditions

DOE PAGES

Stewart, James A.; Kohnert, Aaron A.; Capolungo, Laurent; ...

2018-03-06

The complexity of radiation effects in a material’s microstructure makes developing predictive models a difficult task. In principle, a complete list of all possible reactions between defect species being considered can be used to elucidate damage evolution mechanisms and its associated impact on microstructure evolution. However, a central limitation is that many models use a limited and incomplete catalog of defect energetics and associated reactions. Even for a given model, estimating its input parameters remains a challenge, especially for complex material systems. Here, we present a computational analysis to identify the extent to which defect accumulation, energetics, and irradiation conditionsmore » can be determined via forward and reverse regression models constructed and trained from large data sets produced by cluster dynamics simulations. A global sensitivity analysis, via Sobol’ indices, concisely characterizes parameter sensitivity and demonstrates how this can be connected to variability in defect evolution. Based on this analysis and depending on the definition of what constitutes the input and output spaces, forward and reverse regression models are constructed and allow for the direct calculation of defect accumulation, defect energetics, and irradiation conditions. Here, this computational analysis, exercised on a simplified cluster dynamics model, demonstrates the ability to design predictive surrogate and reduced-order models, and provides guidelines for improving model predictions within the context of forward and reverse engineering of mathematical models for radiation effects in a materials’ microstructure.« less

Design and analysis of forward and reverse models for predicting defect accumulation, defect energetics, and irradiation conditions

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

Stewart, James A.; Kohnert, Aaron A.; Capolungo, Laurent

The complexity of radiation effects in a material’s microstructure makes developing predictive models a difficult task. In principle, a complete list of all possible reactions between defect species being considered can be used to elucidate damage evolution mechanisms and its associated impact on microstructure evolution. However, a central limitation is that many models use a limited and incomplete catalog of defect energetics and associated reactions. Even for a given model, estimating its input parameters remains a challenge, especially for complex material systems. Here, we present a computational analysis to identify the extent to which defect accumulation, energetics, and irradiation conditionsmore » can be determined via forward and reverse regression models constructed and trained from large data sets produced by cluster dynamics simulations. A global sensitivity analysis, via Sobol’ indices, concisely characterizes parameter sensitivity and demonstrates how this can be connected to variability in defect evolution. Based on this analysis and depending on the definition of what constitutes the input and output spaces, forward and reverse regression models are constructed and allow for the direct calculation of defect accumulation, defect energetics, and irradiation conditions. Here, this computational analysis, exercised on a simplified cluster dynamics model, demonstrates the ability to design predictive surrogate and reduced-order models, and provides guidelines for improving model predictions within the context of forward and reverse engineering of mathematical models for radiation effects in a materials’ microstructure.« less

Closing loop base pairs in RNA loop-loop complexes: structural behavior, interaction energy and solvation analysis through molecular dynamics simulations.

PubMed

Golebiowski, Jérôme; Antonczak, Serge; Fernandez-Carmona, Juan; Condom, Roger; Cabrol-Bass, Daniel

2004-12-01

Nanosecond molecular dynamics using the Ewald summation method have been performed to elucidate the structural and energetic role of the closing base pair in loop-loop RNA duplexes neutralized by Mg2+ counterions in aqueous phases. Mismatches GA, CU and Watson-Crick GC base pairs have been considered for closing the loop of an RNA in complementary interaction with HIV-1 TAR. The simulations reveal that the mismatch GA base, mediated by a water molecule, leads to a complex that presents the best compromise between flexibility and energetic contributions. The mismatch CU base pair, in spite of the presence of an inserted water molecule, is too short to achieve a tight interaction at the closing-loop junction and seems to force TAR to reorganize upon binding. An energetic analysis has allowed us to quantify the strength of the interactions of the closing and the loop-loop pairs throughout the simulations. Although the water-mediated GA closing base pair presents an interaction energy similar to that found on fully geometry-optimized structure, the water-mediated CU closing base pair energy interaction reaches less than half the optimal value.

Successes and failures of Hubbard-corrected density functional theory. The case of Mg doped LiCoO 2

DOE PAGES

Santana Palacio, Juan A.; Kim, Jeongnim; Kent, Paul R.; ...

2014-10-28

We have evaluated the successes and failures of the Hubbard-corrected density functional theory approach to study Mg doping of LiCoO 2. We computed the effect of the U parameter on the energetic, geometric, and electronic properties of two possible doping mechanisms: (1) substitution of Mg onto a Co (or Li) site with an associated impurity state and (2) formation of impurity-state-free complexes of substitutional Mg and point defects in LiCoO 2. We find that formation of impurity states results in changes on the valency of Co in LiCoO 2. Variation of the Co U shifts the energy of the impuritymore » state, resulting in energetic, geometric, and electronic properties that depend significantly on the specific value of U. In contrast, the properties of the impurity-state-free complexes are insensitive to U. These results identify reasons for the strong dependence on the doping properties on the chosen value of U and for the overall difficulty of achieving agreement with the experimentally known energetic and electronic properties of doped transition metal oxides such as LiCoO 2.« less

Tetrel bond-σ-hole bond as a preliminary stage of the SN2 reaction.

PubMed

Grabowski, Sławomir J

2014-02-07

MP2/aug-cc-pVTZ calculations were carried out on complexes of ZH4, ZFH3 and ZF4 (Z = C, Si and Ge) molecules with HCN, LiCN and Cl(-) species acting as Lewis bases through nitrogen centre or chlorine ion. Z-Atoms in these complexes usually act as Lewis acid centres forming σ-hole bonds with Lewis bases. Such noncovalent interactions may adopt a name of tetrel bonds since they concern the elements of the group IV. There are exceptions for complexes of CH4 and CF4, as well as for the F4SiNCH complex where the tetrel bond is not formed. The energetic and geometrical parameters of the complexes were analyzed and numerous correlations between them were found. The Quantum Theory of 'Atoms in Molecules' and Natural Bonds Orbital (NBO) method used here should deepen the understanding of the nature of the tetrel bond. An analysis of the electrostatic potential surfaces of the interacting species is performed. The electron charge redistribution, being the result of the tetrel bond formation, is the same as that of the SN2 reaction. The energetic and geometrical parameters of the complexes analyzed here correspond to different stages of the SN2 process.

A modelling methodology to assess the effect of insect pest control on agro-ecosystems.

PubMed

Wan, Nian-Feng; Ji, Xiang-Yun; Jiang, Jie-Xian; Li, Bo

2015-04-23

The extensive use of chemical pesticides for pest management in agricultural systems can entail risks to the complex ecosystems consisting of economic, ecological and social subsystems. To analyze the negative and positive effects of external or internal disturbances on complex ecosystems, we proposed an ecological two-sidedness approach which has been applied to the design of pest-controlling strategies for pesticide pollution management. However, catastrophe theory has not been initially applied to this approach. Thus, we used an approach of integrating ecological two-sidedness with a multi-criterion evaluation method of catastrophe theory to analyze the complexity of agro-ecosystems disturbed by the insecticides and screen out the best insect pest-controlling strategy in cabbage production. The results showed that the order of the values of evaluation index (RCC/CP) for three strategies in cabbage production was "applying frequency vibration lamps and environment-friendly insecticides 8 times" (0.80) < "applying trap devices and environment-friendly insecticides 9 times" (0.83) < "applying common insecticides 14 times" (1.08). The treatment "applying frequency vibration lamps and environment-friendly insecticides 8 times" was considered as the best insect pest-controlling strategy in cabbage production in Shanghai, China.

A modelling methodology to assess the effect of insect pest control on agro-ecosystems

PubMed Central

Wan, Nian-Feng; Ji, Xiang-Yun; Jiang, Jie-Xian; Li, Bo

2015-01-01

The extensive use of chemical pesticides for pest management in agricultural systems can entail risks to the complex ecosystems consisting of economic, ecological and social subsystems. To analyze the negative and positive effects of external or internal disturbances on complex ecosystems, we proposed an ecological two-sidedness approach which has been applied to the design of pest-controlling strategies for pesticide pollution management. However, catastrophe theory has not been initially applied to this approach. Thus, we used an approach of integrating ecological two-sidedness with a multi-criterion evaluation method of catastrophe theory to analyze the complexity of agro-ecosystems disturbed by the insecticides and screen out the best insect pest-controlling strategy in cabbage production. The results showed that the order of the values of evaluation index (RCC/CP) for three strategies in cabbage production was “applying frequency vibration lamps and environment-friendly insecticides 8 times” (0.80) < “applying trap devices and environment-friendly insecticides 9 times” (0.83) < “applying common insecticides 14 times” (1.08). The treatment “applying frequency vibration lamps and environment-friendly insecticides 8 times” was considered as the best insect pest-controlling strategy in cabbage production in Shanghai, China. PMID:25906199

Molecular Pathways: Is AMPK a Friend or a Foe in Cancer?

PubMed Central

Hardie, D. Grahame

2015-01-01

The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status expressed in essentially all eukaryotic cells. Once activated by energetic stress via a mechanism that detects increases in AMP:ATP and ADP:ATP ratios, AMPK acts to restore energy homeostasis by switching on catabolic pathways that generate ATP, while switching off ATP-consuming processes, including anabolic pathways required for cell growth and proliferation. AMPK activation promotes the glucose-sparing, oxidative metabolism utilized by most quiescent cells, rather than the rapid glucose uptake and glycolysis used by most proliferating cells. Numerous pharmacological activators of AMPK are known, including drugs in long use such as salicylate and metformin, and there is evidence that regular use of either of the latter provides protection against development of cancer. Tumor cells appear to be under selection pressure to down-regulate AMPK, thus limiting its restraining influence on cell growth and proliferation, and several interesting mechanisms by which this occurs are discussed. Paradoxically, however, a complete loss of AMPK function, which appears to be rare in human cancers, may be deleterious to survival of tumor cells. AMPK can therefore either be a friend and a foe in cancer, depending on the context. PMID:26152739

Social Identity Complexity, Cross-Ethnic Friendships, and Intergroup Attitudes in Urban Middle Schools

ERIC Educational Resources Information Center

Knifsend, Casey A.; Juvonen, Jaana

2014-01-01

This study investigated contextual antecedents (i.e., cross-ethnic peers and friends) and correlates (i.e., intergroup attitudes) of social identity complexity in seventh grade. Social identity complexity refers to the perceived overlap among social groups with which youth identify. Identifying mostly with out-of-school sports, religious…

Control of exciton confinement in quantum dot-organic complexes through energetic alignment of interfacial orbitals.

PubMed

Frederick, Matthew T; Amin, Victor A; Swenson, Nathaniel K; Ho, Andrew Y; Weiss, Emily A

2013-01-09

This paper describes a method to control the quantum confinement, and therefore the energy, of excitonic holes in CdSe QDs through adsorption of the hole-delocalizing ligand phenyldithiocarbamate, PTC, and para substitutions of the phenyl ring of this ligand with electron-donating or -withdrawing groups. These substitutions control hole delocalization in the QDs through the energetic alignment of the highest occupied orbitals of PTC with the highest density-of-states region of the CdSe valence band, to which PTC couples selectively.

Supporting cystic fibrosis disease management during adolescence: the role of family and friends.

PubMed

Barker, D H; Driscoll, K A; Modi, A C; Light, M J; Quittner, A L

2012-07-01

Successful management of a complex disease, such as cystic fibrosis (CF), requires support from family and friends; however, few studies have examined social support in adolescents with CF. Twenty-four adolescents were interviewed about the support they receive from family and friends. Interviews were transcribed, coded and analysed to determine the types, frequency and perceived supportiveness of specific behaviours. Both family and friends provided treatment-related support to adolescents with CF. Family provided more tangible support and friends provided more relational support. Adolescents also reported that the manner, timing and context of support behaviours influenced their perceptions of the behaviours' supportiveness. A subset of adolescents (17%) chose not to disclose their diagnosis to their friends. The provision of support appears to be distinct from adolescent's perception of support and there may be some behaviours, such as treatment reminders, that are important to disease management but viewed as less supportive by adolescents. Facilitating increased social support holds the promise of improving disease management during adolescents, but more work is need to understand which aspects of support are related to management outcomes. © 2011 Blackwell Publishing Ltd.

“Maybe They Don't Even Know That I Exist”: Challenges Faced by Family Members and Friends of Patients with Advanced Kidney Disease

PubMed Central

Szarka, Jackie; McFarland, Lynne V.; Vig, Elizabeth K.; Sudore, Rebecca L.; Crowley, Susan; Reinke, Lynn F.; Trivedi, Ranak; Taylor, Janelle S.

2017-01-01

Background and objectives Family members and friends of patients with advanced chronic illness are increasingly called on to assist with ever more complex medical care and treatment decisions arising late in the course of illness. Our goal was to learn about the experiences of family members and friends of patients with advanced kidney disease. Design, setting, participants, & measurements As part of a study intended to identify opportunities to enhance advance care planning, we conducted semistructured interviews at the Veterans Affairs Puget Sound Health Care System with 17 family members and friends of patients with advanced kidney disease. Interviews were conducted between April of 2014 and May of 2016 and were audiotaped, transcribed, and analyzed inductively using grounded theory to identify emergent themes. Results The following three themes emerged from interviews with patients’ family members and friends: (1) their roles in care and planning were fluid over the course of the patient’s illness, shaped by the patients’ changing needs and their readiness to involve those close to them; (2) their involvement in patients’ care was strongly shaped by health care system needs. Family and friends described filling gaps left by the health care system and how their involvement in care and decision-making was at times constrained and at other times expected by providers, depending on system needs; and (3) they described multiple sources of tension and conflict in their interactions with patients and the health care system, including instances of being pitted against the patient. Conclusions Interviews with family members and friends of patients with advanced kidney disease provide a window on the complex dynamics shaping their engagement in patients’ care, and highlight the potential value of offering opportunities for engagement throughout the course of illness. PMID:28356337

A "spoon full of sugar" helps the medicine go down: How a participant friendly version of a psychophysics task significantly improves task engagement, performance and data quality in a typical adult sample.

PubMed

Smith, Marie L; Cesana, M Letizia; Farran, Emily K; Karmiloff-Smith, Annette; Ewing, Louise

2018-06-01

Few would argue that the unique insights brought by studying the typical and atypical development of psychological processes are essential to building a comprehensive understanding of the brain. Often, however, the associated challenges of working with non-standard adult populations results in the more complex psychophysical paradigms being rejected as too complex. Recently we created a child- (and clinical group) friendly implementation of one such technique - the reverse-correlation Bubbles approach - and noted an associated performance boost in adult participants. Here, we compare the administration of three different versions of this participant-friendly task in the same adult participants to empirically confirm that introducing elements in the experiment with the sole purpose of improving the participant experience, not only boosts the participant's engagement and motivation for the task but results in a significantly improved objective task performance and stronger statistical results.

Henry Sigerist and the history of medicine in Latin America: his correspondence with Juan R. Beltran.

PubMed

de Asúa, Miguel

2005-01-01

During the years of World War II, the American Association for the History of Medicine fostered a Pan-American policy aimed at establishing relationships with Latin American historians of medicine. Juan R. Beltrán, professor of history of medicine at the University of Buenos Aires, also pursued an energetic program of academic diplomacy. The correspondence between Henry Sigerist and Beltrán makes manifest that by 1941 good channels of communication were established between Baltimore and Buenos Aires, but the friendly links did not last long. The motives for this can be found in the competing aims of the AAHM and Beltrán, and the pattern of international relationships during the war years.

Christian charity: the Unitarian Service Committee's relief activities on behalf of refugees from Nazism, 1940-5.

PubMed

GENIZI, H

1987-01-01

The Unitanan Service Committee (USC) was one of a number of American Christian organizations which aided refugees, mostly Christians, during the Nazi period. Although modelled somewhat after the Quakers' American Friends Service Committee, the USC differed from this group in its opposition to neutrality and openly expressed support for the Allied cause Despite its late start (1940) in overseas work, the USC was very energetic and creative in aiding refugees. The Committee was also the only relief agency in Lisbon specializing in care for illegal refugees. This case study points to how much might have been accomplished had there been greater determination on the part of more people to aid the innocents endangered by the Nazis.

First-order system least squares and the energetic variational approach for two-phase flow

NASA Astrophysics Data System (ADS)

Adler, J. H.; Brannick, J.; Liu, C.; Manteuffel, T.; Zikatanov, L.

2011-07-01

This paper develops a first-order system least-squares (FOSLS) formulation for equations of two-phase flow. The main goal is to show that this discretization, along with numerical techniques such as nested iteration, algebraic multigrid, and adaptive local refinement, can be used to solve these types of complex fluid flow problems. In addition, from an energetic variational approach, it can be shown that an important quantity to preserve in a given simulation is the energy law. We discuss the energy law and inherent structure for two-phase flow using the Allen-Cahn interface model and indicate how it is related to other complex fluid models, such as magnetohydrodynamics. Finally, we show that, using the FOSLS framework, one can still satisfy the appropriate energy law globally while using well-known numerical techniques.

Metastable Autoionizing States of Molecules and Radicals in Highly Energetic Environment

DTIC Science & Technology

2016-03-22

electronic states. The specific aims are to develop and calibrate complex-scaled equation-of-motion coupled cluster (cs-EOM- CC ) and CAP (complex...absorbing potential) augmented EOM- CC methods. We have implemented and benchmarked cs-EOM-CCSD and CAP- augmented EOM-CCSD methods for excitation energies...motion coupled cluster (cs-EOM- CC ) and CAP (complex absorbing potential) augmented EOM- CC methods. We have implemented and benchmarked cs-EOM-CCSD and

Sub-500 fs electronically nonadiabatic chemical dynamics of energetic molecules from the S1 excited state: Ab initio multiple spawning study

NASA Astrophysics Data System (ADS)

Ghosh, Jayanta; Gajapathy, Harshad; Konar, Arindam; Narasimhaiah, Gowrav M.; Bhattacharya, Atanu

2017-11-01

Energetic materials store a large amount of chemical energy. Different ignition processes, including laser ignition and shock or compression wave, initiate the energy release process by first promoting energetic molecules to the electronically excited states. This is why a full understanding of initial steps of the chemical dynamics of energetic molecules from the excited electronic states is highly desirable. In general, conical intersection (CI), which is the crossing point of multidimensional electronic potential energy surfaces, is well established as a controlling factor in the initial steps of chemical dynamics of energetic molecules following their electronic excitations. In this article, we have presented different aspects of the ultrafast unimolecular relaxation dynamics of energetic molecules through CIs. For this task, we have employed ab initio multiple spawning (AIMS) simulation using the complete active space self-consistent field (CASSCF) electronic wavefunction and frozen Gaussian-based nuclear wavefunction. The AIMS simulation results collectively reveal that the ultrafast relaxation step of the best energetic molecules (which are known to exhibit very good detonation properties) is completed in less than 500 fs. Many, however, exhibit sub-50 fs dynamics. For example, nitro-containing molecules (including C-NO2, N-NO2, and O-NO2 active moieties) relax back to the ground state in approximately 40 fs through similar (S1/S0)CI conical intersections. The N3-based energetic molecule undergoes the N2 elimination process in 40 fs through the (S1/S0)CI conical intersection. Nitramine-Fe complexes exhibit sub-50 fs Fe-O and N-O bond dissociation through the respective (S1/S0)CI conical intersection. On the other hand, tetrazine-N-oxides, which are known to exhibit better detonation properties than tetrazines, undergo internal conversion in a 400-fs time scale, while the relaxation time of tetrazine is very long (about 100 ns). Many other characteristics of sub-500 fs nonadiabatic decay of energetic molecules are discussed. In the end, many unresolved issues associated with the ultrafast nonadiabatic chemical dynamics of energetic molecules are presented.

Plasma Interaction and Energetic Particle Dynamics near Callisto

NASA Astrophysics Data System (ADS)

Liuzzo, L.; Simon, S.; Feyerabend, M.; Motschmann, U. M.

2017-12-01

Callisto's magnetic environment is characterized by a complex admixture of induction signals from its conducting subsurface ocean, the interaction of corotating Jovian magnetospheric plasma with the moon's ionosphere and induced dipole, and the non-linear coupling between the effects. In contrast to other Galilean moons, ion gyroradii near Callisto are comparable to its size, requiring a kinetic treatment of the interaction region near the moon. Thus, we apply the hybrid simulation code AIKEF to constrain the competing effects of plasma interaction and induction. We determine their influence on the magnetic field signatures measured by Galileo during various Callisto flybys. We use the magnetic field calculated by the model to investigate energetic particle dynamics and their effect on Callisto's environment. From this, we provide a map of global energetic particle precipitation onto Callisto's surface, which may contribute to the generation of its atmosphere.

A kinetic model for stress generation in thin films grown from energetic vapor fluxes

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

Chason, E.; Karlson, M.; Colin, J. J.

We have developed a kinetic model for residual stress generation in thin films grown from energetic vapor fluxes, encountered, e.g., during sputter deposition. The new analytical model considers sub-surface point defects created by atomic peening, along with processes treated in already existing stress models for non-energetic deposition, i.e., thermally activated diffusion processes at the surface and the grain boundary. According to the new model, ballistically induced sub-surface defects can get incorporated as excess atoms at the grain boundary, remain trapped in the bulk, or annihilate at the free surface, resulting in a complex dependence of the steady-state stress on themore » grain size, the growth rate, as well as the energetics of the incoming particle flux. We compare calculations from the model with in situ stress measurements performed on a series of Mo films sputter-deposited at different conditions and having different grain sizes. The model is able to reproduce the observed increase of compressive stress with increasing growth rate, behavior that is the opposite of what is typically seen under non-energetic growth conditions. On a grander scale, this study is a step towards obtaining a comprehensive understanding of stress generation and evolution in vapor deposited polycrystalline thin films.« less

Genetic algorithm and graph theory based matrix factorization method for online friend recommendation.

PubMed

Li, Qu; Yao, Min; Yang, Jianhua; Xu, Ning

2014-01-01

Online friend recommendation is a fast developing topic in web mining. In this paper, we used SVD matrix factorization to model user and item feature vector and used stochastic gradient descent to amend parameter and improve accuracy. To tackle cold start problem and data sparsity, we used KNN model to influence user feature vector. At the same time, we used graph theory to partition communities with fairly low time and space complexity. What is more, matrix factorization can combine online and offline recommendation. Experiments showed that the hybrid recommendation algorithm is able to recommend online friends with good accuracy.

Probing interfacial energetics and charge transfer kinetics in semiconductor nanocomposites: New insights into heterostructured TiO 2/BiVO 4 photoanodes

DOE PAGES

Hess, Lucas H.; Cooper, Jason K.; Loiudice, Anna; ...

2017-02-28

Heterostructured nanocomposites offer promise for creating systems exhibiting functional properties that exceed those of the isolated components. For solar energy conversion, such combinations of semiconducting nanomaterials can be used to direct charge transfer along pathways that reduce recombination and promote efficient charge extraction. However, interfacial energetics and associated kinetic pathways often differ significantly from predictions derived from the characteristics of pure component materials, particularly at the nanoscale. Here, the emergent properties of TiO 2/BiVO 4 nanocomposite photoanodes are explored using a combination of X-ray and optical spectroscopies, together with photoelectrochemical (PEC) characterization. Application of these methods to both the puremore » components and the fully assembled nanocomposites reveals unpredicted interfacial energetic alignment, which promotes ultrafast injection of electrons from BiVO 4 into TiO 2. Physical charge separation yields extremely long-lived photoexcited states and correspondingly enhanced photoelectrochemical functionality. This work highlights the importance of probing emergent interfacial energetic alignment and kinetic processes for understanding mechanisms of solar energy conversion in complex nanocomposites.« less

Recent advances in modeling Hugoniots with Cheetah

NASA Astrophysics Data System (ADS)

Glaesemann, Kurt

2005-07-01

The detonation of an energetic material is the result of a complex interaction between kinetic chemical reactions and thermodynamic chemical equilibrium. Unfortunately, little is known concerning the detailed chemical kinetics of reacting energetic materials. Cheetah uses rate laws to treat species with the slowest chemical reactions, while assuming other chemical species are in equilibrium. Cheetah supports a wide range of elements and condensed detonation products and can also be applied to gas phase reactions. Improvements have been made to Cheetah's equilibrium solver, that allow it to find a wider range of thermodynamic states. Many of the difficulties experienced by users in earlier versions of Cheetah have been fixed. New capabilities have also been added. The ultimate result is a code that can be applied to a wide range of shock problems involving both energetic and non-energetic materials. New experimental validations of Cheetah's equation of state methodology have been performed, including both reacted and unreacted Hugoniots. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Respiration and substrate transport rates as well as reactive oxygen species production distinguish mitochondria from brain and liver.

PubMed

Gusdon, Aaron M; Fernandez-Bueno, Gabriel A; Wohlgemuth, Stephanie; Fernandez, Jenelle; Chen, Jing; Mathews, Clayton E

2015-09-10

Aberrant mitochondrial function, including excessive reactive oxygen species (ROS) production, has been implicated in the pathogenesis of human diseases. The use of mitochondrial inhibitors to ascertain the sites in the electron transport chain (ETC) resulting in altered ROS production can be an important tool. However, the response of mouse mitochondria to ETC inhibitors has not been thoroughly assessed. Here we set out to characterize the differences in phenotypic response to ETC inhibitors between the more energetically demanding brain mitochondria and less energetically demanding liver mitochondria in commonly utilized C57BL/6J mice. We show that in contrast to brain mitochondria, inhibiting distally within complex I or within complex III does not increase liver mitochondrial ROS production supported by complex I substrates, and liver mitochondrial ROS production supported by complex II substrates occurred primarily independent of membrane potential. Complex I, II, and III enzymatic activities and membrane potential were equivalent between liver and brain and responded to ETC. inhibitors similarly. Brain mitochondria exhibited an approximately two-fold increase in complex I and II supported respiration compared with liver mitochondria while exhibiting similar responses to inhibitors. Elevated NADH transport and heightened complex II-III coupled activity accounted for increased complex I and II supported respiration, respectively in brain mitochondria. We conclude that important mechanistic differences exist between mouse liver and brain mitochondria and that mouse mitochondria exhibit phenotypic differences compared with mitochondria from other species.

When friends disappoint: boys' and girls' responses to transgressions of friendship expectations.

PubMed

MacEvoy, Julie Paquette; Asher, Steven R

2012-01-01

In this study, the prevailing view that girls are pervasively more skilled in their friendships than boys was challenged by examining whether girls respond more negatively than boys when a friend violates core friendship expectations. Fourth- and fifth-grade children (n = 267) responded to vignettes depicting transgressions involving a friend's betrayal, unreliability, or failure to provide support or help. Results indicated that girls were more troubled by the transgressions, more strongly endorsed various types of negative relationship interpretations of the friend's actions, and reported more anger and sadness than did boys. Girls also endorsed revenge goals and aggressive strategies just as much as boys. These findings lead to a more complex view of boys' and girls' friendship competencies. © 2011 The Authors. Child Development © 2011 Society for Research in Child Development, Inc.

Stability of M 3S 3 complexes on fcc M(111) surfaces: M = Au, Ag, Cu, and Ni

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

Liu, Da-Jiang; Lee, Jiyoung; Windus, Theresa L.

Density Functional Theory is utilized to assess the stability of metal (M)-sulfur (S) complexes adsorbed on fcc M(111) surfaces, specifically considering S-decorated planar M trimers, M 3S 3. Scanning Tunneling Microscopy studies have identified structures proposed to be Ni 3S 3 on Ni(111), and Au 3S 3 on Au(111). In addition, Cu 3S 3 on Cu(111) has been suggested to facilitate enhanced Cu surface mass transport. Our analysis considers M 3S 3 complexes for M = Au, Ag, Cu, and Ni, assessing key measures of stability on surfaces, and also comparing behavior with trends in gas-phase stability. These surface andmore » gas-phase analyses are systematically related within the framework of Hess’s law, which allows elucidation of various contributions to the overall energetics. In all cases, the adsorbed complex is stable relative to its separated constituents adsorbed on the terrace. However, only for Ag does one find a negative energy of formation from excess S on terraces and M extracted from kink sites along step edges, implying spontaneous complex formation for this pathway. We interpret various experimental observations in the context of our results for energetics.« less

Stability of M 3S 3 complexes on fcc M(111) surfaces: M = Au, Ag, Cu, and Ni

DOE PAGES

Liu, Da-Jiang; Lee, Jiyoung; Windus, Theresa L.; ...

2018-02-08

Density Functional Theory is utilized to assess the stability of metal (M)-sulfur (S) complexes adsorbed on fcc M(111) surfaces, specifically considering S-decorated planar M trimers, M 3S 3. Scanning Tunneling Microscopy studies have identified structures proposed to be Ni 3S 3 on Ni(111), and Au 3S 3 on Au(111). In addition, Cu 3S 3 on Cu(111) has been suggested to facilitate enhanced Cu surface mass transport. Our analysis considers M 3S 3 complexes for M = Au, Ag, Cu, and Ni, assessing key measures of stability on surfaces, and also comparing behavior with trends in gas-phase stability. These surface andmore » gas-phase analyses are systematically related within the framework of Hess’s law, which allows elucidation of various contributions to the overall energetics. In all cases, the adsorbed complex is stable relative to its separated constituents adsorbed on the terrace. However, only for Ag does one find a negative energy of formation from excess S on terraces and M extracted from kink sites along step edges, implying spontaneous complex formation for this pathway. We interpret various experimental observations in the context of our results for energetics.« less

Excited State Energetics and Dynamics of Large Molecules, Complexes and Clusters

DTIC Science & Technology

1988-07-01

tetracene. Ar (n=l-5) complexes, providing central information on microscopic solvent shifts. These studies were extended to M-metal atom com - plexes...corresponding to the bare molecule. At higher 2. Experimental stagnation pressures of Ar (p = 80-150 Toff) the contributions of van der Waals DPB. Ar, com - Our...gas aromatic-molecule complexes were docu- So - S1 transition of the trans-stilbene (TS)-Ar com - mented experimentally to lie in the rango - 30- plex

Energetics of dendrimer binding to HIV-1 gp120-CD4 complex and mechanismic aspects of its role as an entry-inhibitor

NASA Astrophysics Data System (ADS)

Saurabh, Suman; Sahoo, Anil Kumar; Maiti, Prabal K.

2016-10-01

Experiments and computational studies have established that de-protonated dendrimers (SPL7013 and PAMAM) act as entry-inhibitors of HIV. SPL7013 based Vivagel is currently under clinical development. The dendrimer binds to gp120 in the gp120-CD4 complex, destabilizes it by breaking key contacts between gp120 and CD4 and prevents viral entry into target cells. In this work, we provide molecular details and energetics of the formation of the SPL7013-gp120-CD4 ternary complex and decipher modes of action of the dendrimer in preventing viral entry. It is also known from experiments that the dendrimer binds weakly to gp120 that is not bound to CD4. It binds even more weakly to the CD4-binding region of gp120 and thus cannot directly block gp120-CD4 complexation. In this work, we examine the feasibility of dendrimer binding to the gp120-binding region of CD4 and directly blocking gp120-CD4 complex formation. We find that the process of the dendrimer binding to CD4 can compete with gp120-CD4 binding due to comparable free energy change for the two processes, thus creating a possibility for the dendrimer to directly block gp120-CD4 complexation by binding to the gp120-binding region of CD4.

Mechanism and Energetics of Charybdotoxin Unbinding from a Potassium Channel from Molecular Dynamics Simulations

PubMed Central

Chen, Po-chia; Kuyucak, Serdar

2009-01-01

Ion channel-toxin complexes are ideal systems for computational studies of protein-ligand interactions, because, in most cases, the channel axis provides a natural reaction coordinate for unbinding of a ligand and a wealth of physiological data is available to check the computational results. We use a recently determined structure of a potassium channel-charybdotoxin complex in molecular dynamics simulations to investigate the mechanism and energetics of unbinding. Pairs of residues on the channel protein and charybdotoxin that are involved in the binding are identified, and their behavior is traced during umbrella-sampling simulations as charybdotoxin is moved away from the binding site. The potential of mean force for the unbinding of charybdotoxin is constructed from the umbrella sampling simulations using the weighted histogram analysis method, and barriers observed are correlated with specific breaking of interactions and influx of water molecules into the binding site. Charybdotoxin is found to undergo conformational changes as a result of the reaction coordinate choice—a nontrivial decision for larger ligands—which we explore in detail, and for which we propose solutions. Agreement between the calculated and the experimental binding energies is obtained once the energetic consequences of these conformational changes are included in the calculations. PMID:19348743

The Sun: Source of the Earth's Energy

NASA Technical Reports Server (NTRS)

Thompson, Barbara J.; Fisher, Richard R. (Technical Monitor)

2001-01-01

The Sun is the primary source of the Earth's energy. However, due to the complexity in the way the energy affects Earth, the various solar sources of the energy, and the variation exhibited by the Sun it is difficult to understand and predict the Earth's response to solar drivers. In addition to visible light the radiant energy of the Sun can exhibit variation in nearly all wavelengths, which can vary over nearly all timescales. Depending on the wavelength of the incident radiation the light can deposit energy in a wide variety or locations and drive processes from below Earth's surface to interplanetary space. Other sources of energy impacting Earth include energetic particles, magnetic fields, and mass and flow variations in the solar wind. Many of these variable energetic processes cannot be coupled and recent results continue to demonstrate that the complex dynamics of the Sun can have a great range of measurable impacts on Earth.

Bulk and surface properties of liquid Al-Cr and Cr-Ni alloys.

PubMed

Novakovic, R

2011-06-15

The energetics of mixing and structural arrangement in liquid Al-Cr and Cr-Ni alloys has been analysed through the study of surface properties (surface tension and surface segregation), dynamic properties (chemical diffusion) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory. The Al-Cr phase diagram exhibits the existence of different intermetallic compounds in the solid state, while that of Cr-Ni is a simple eutectic-type phase diagram at high temperatures and includes the low-temperature peritectoid reaction in the range near a CrNi(2) composition. Accordingly, the mixing behaviour in Al-Cr and Cr-Ni alloy melts was studied using the complex formation model in the weak interaction approximation and by postulating Al(8)Cr(5) and CrNi(2) chemical complexes, respectively, as energetically favoured.

Prediction of kinase-inhibitor binding affinity using energetic parameters

PubMed Central

Usha, Singaravelu; Selvaraj, Samuel

2016-01-01

The combination of physicochemical properties and energetic parameters derived from protein-ligand complexes play a vital role in determining the biological activity of a molecule. In the present work, protein-ligand interaction energy along with logP values was used to predict the experimental log (IC50) values of 25 different kinase-inhibitors using multiple regressions which gave a correlation coefficient of 0.93. The regression equation obtained was tested on 93 kinase-inhibitor complexes and an average deviation of 0.92 from the experimental log IC50 values was shown. The same set of descriptors was used to predict binding affinities for a test set of five individual kinase families, with correlation values > 0.9. We show that the protein-ligand interaction energies and partition coefficient values form the major deterministic factors for binding affinity of the ligand for its receptor. PMID:28149052

The role of gender and friends' gender on peer socialization of adolescent drinking: a prospective multilevel social network analysis.

PubMed

Deutsch, Arielle R; Steinley, Douglas; Slutske, Wendy S

2014-09-01

Although socializing effects of friends' drinking on adolescent drinking behavior have been firmly established in previous literature, study results on the importance of gender, as well as the specific role that gender may play in peer socialization, are very mixed. Given the increasing importance of gender in friendships (particularly opposite-sex friendships) during adolescence, it is necessary to better understand the nuanced roles that gender can play in peer socialization effects on alcohol use. In addition, previous studies focusing on the interplay between individual gender and friends' gender have been largely dyadic; less is known about potential gendered effects of broader social networks. The current study sought to further investigate potential effects of gender on friends' influence on adolescent drinking behavior with particular emphasis on the number of same-sex and opposite-sex friends within one's friendship network, as well as closeness to these friends. Using Waves I and II of the saturated sample of the National Longitudinal Study of Adolescent Health (Add Health), adolescent friendship networks were used to calculate the mean drinking behaviors of adolescent friends. Multi-level models estimated the effects of individual drinking behaviors, friend drinking behaviors, and school-level drinking behaviors on adolescent drinking 1 year later, as well as moderating effects of gender composition of friendship groups and male and female friend closeness on the relationship between friends' drinking behaviors and adolescent drinking behavior. Results documented that gender composition of friendship groups did not influence the effect of friends' drinking on individual drinking 1 year later. However, closeness to friends did influence this relationship. As closeness to male friends decreased, the influence of their drinking behavior increased, for both boys and girls. A similar effect was found for female friends, but only for boys. Female friend closeness did not affect the relationship between peer alcohol socialization and girls' alcohol use. The findings indicate that the role of gender on alcohol socialization may be more complex than previously thought, particularly when examining the potential role that alcohol use may play as a mechanism for social bonding within opposite-sex friendships and same-sex male friendships.

Generalized friendship paradox in complex networks: The case of scientific collaboration

NASA Astrophysics Data System (ADS)

Eom, Young-Ho; Jo, Hang-Hyun

2014-04-01

The friendship paradox states that your friends have on average more friends than you have. Does the paradox ``hold'' for other individual characteristics like income or happiness? To address this question, we generalize the friendship paradox for arbitrary node characteristics in complex networks. By analyzing two coauthorship networks of Physical Review journals and Google Scholar profiles, we find that the generalized friendship paradox (GFP) holds at the individual and network levels for various characteristics, including the number of coauthors, the number of citations, and the number of publications. The origin of the GFP is shown to be rooted in positive correlations between degree and characteristics. As a fruitful application of the GFP, we suggest effective and efficient sampling methods for identifying high characteristic nodes in large-scale networks. Our study on the GFP can shed lights on understanding the interplay between network structure and node characteristics in complex networks.

Generalized friendship paradox in complex networks: The case of scientific collaboration

PubMed Central

Eom, Young-Ho; Jo, Hang-Hyun

2014-01-01

The friendship paradox states that your friends have on average more friends than you have. Does the paradox “hold” for other individual characteristics like income or happiness? To address this question, we generalize the friendship paradox for arbitrary node characteristics in complex networks. By analyzing two coauthorship networks of Physical Review journals and Google Scholar profiles, we find that the generalized friendship paradox (GFP) holds at the individual and network levels for various characteristics, including the number of coauthors, the number of citations, and the number of publications. The origin of the GFP is shown to be rooted in positive correlations between degree and characteristics. As a fruitful application of the GFP, we suggest effective and efficient sampling methods for identifying high characteristic nodes in large-scale networks. Our study on the GFP can shed lights on understanding the interplay between network structure and node characteristics in complex networks. PMID:24714092

Children with autism and their friends: a multidimensional study of friendship in high-functioning autism spectrum disorder.

PubMed

Bauminger, Nirit; Solomon, Marjorie; Aviezer, Anat; Heung, Kelly; Gazit, Lilach; Brown, John; Rogers, Sally J

2008-02-01

This study of Israeli and American preadolescent children examined characteristics of friendship in 44 children with high-functioning autism spectrum disorder (HFASD) compared to 38 typically developing children (TYP), as they interacted with a close friend Participants were 8-12 years of age (HFASD: Israel, n = 24; USA, n = 20; TYP: Israel, n = 23; USA, n = 15), and were matched on SES, receptive language vocabulary, child age, and gender (each study group included one girl). Multidimensional assessments included: individual behaviors of target children and observed child-friend interactions during construction and drawing scenarios; target child's and friend's self-perceived mutual friendship qualities; and mother-reported characteristics (friendship's duration/frequency; friend's age/gender/disability status). Overall, children with HFASD displayed a number of differences on individual and dyadic friendship measures. Both age and verbal abilities affected friendship behaviors. Children with HFASD and their friends perceived friendship qualities similarly, suggesting that preadolescents with HFASD have capacities for interpersonal awareness. Between-group similarities also emerged on several complex social behaviors, suggesting that friendship follows a developmental trajectory in autism and may enhance social interaction skills in autism.

Supporting cystic fibrosis disease management during adolescence: the role of family and friends

PubMed Central

Barker, D. H.; Driscoll, K. A.; Modi, A. C.; Light, M. J.; Quittner, A. L.

2012-01-01

Background Successful management of a complex disease, such as cystic fibrosis (CF), requires support from family and friends; however, few studies have examined social support in adolescents with CF. Methods Twenty-four adolescents were interviewed about the support they receive from family and friends. Interviews were transcribed, coded and analysed to determine the types, frequency and perceived supportiveness of specific behaviours. Results Both family and friends provided treatment-related support to adolescents with CF. Family provided more tangible support and friends provided more relational support. Adolescents also reported that the manner, timing and context of support behaviours influenced their perceptions of the behaviours’ supportiveness. A subset of adolescents (17%) chose not to disclose their diagnosis to their friends. Conclusions The provision of support appears to be distinct from adolescent’s perception of support and there may be some behaviours, such as treatment reminders, that are important to disease management but viewed as less supportive by adolescents. Facilitating increased social support holds the promise of improving disease management during adolescents, but more work is need to understand which aspects of support are related to management outcomes. PMID:21771002

Sparse Partial Equilibrium Tables in Chemically Resolved Reactive Flow

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

Vitello, P; Fried, L E; Pudliner, B

2003-07-14

The detonation of an energetic material is the result of a complex interaction between kinetic chemical reactions and hydrodynamics. Unfortunately, little is known concerning the detailed chemical kinetics of detonations in energetic materials. CHEETAH uses rate laws to treat species with the slowest chemical reactions, while assuming other chemical species are in equilibrium. CHEETAH supports a wide range of elements and condensed detonation products and can also be applied to gas detonations. A sparse hash table of equation of state values, called the ''cache'' is used in CHEETAH to enhance the efficiency of kinetic reaction calculations. For large-scale parallel hydrodynamicmore » calculations, CHEETAH uses MPI communication to updates to the cache. We present here details of the sparse caching model used in the CHEETAH. To demonstrate the efficiency of modeling using a sparse cache model we consider detonations in energetic materials.« less

Energetic protons from a disappearing solar filament

NASA Technical Reports Server (NTRS)

Kahler, S. W.; Cliver, E. W.; Cane, H. V.; Mcguire, R. E.; Stone, R. G.; Sheeley, N. R., Jr.

1985-01-01

A solar energetic (E 50 MeV) particle (SEP) event observed at 1 AU began about 15000 UT on 1981 December 5. This event was associated with a fast coronal mass ejection observed with the Solwind coronagraph on the P78-1 satellite. No metric type 2 or type 4 burst was observed, but a weak interplanetary type 2 burst was observed with the low frequency radio experiment on the International Sun-Earth Explorer-3 satellite. The mass ejection was associated with the eruption of a large solar quiescent filament which lay well away from any active regions. The eruption resulted in an H alpha double ribbon structure which straddled the magnetic inversion line. No impulsive phase was obvious in either the H alpha or the microwave observations. This event indicates that neither a detectable impulsive phase nor a strong or complex magnetic field is necessary for the production of energetic ions.

Sparse Partial Equilibrium Tables in Chemically Resolved Reactive Flow

NASA Astrophysics Data System (ADS)

Vitello, Peter; Fried, Laurence E.; Pudliner, Brian; McAbee, Tom

2004-07-01

The detonation of an energetic material is the result of a complex interaction between kinetic chemical reactions and hydrodynamics. Unfortunately, little is known concerning the detailed chemical kinetics of detonations in energetic materials. CHEETAH uses rate laws to treat species with the slowest chemical reactions, while assuming other chemical species are in equilibrium. CHEETAH supports a wide range of elements and condensed detonation products and can also be applied to gas detonations. A sparse hash table of equation of state values is used in CHEETAH to enhance the efficiency of kinetic reaction calculations. For large-scale parallel hydrodynamic calculations, CHEETAH uses parallel communication to updates to the cache. We present here details of the sparse caching model used in the CHEETAH coupled to an ALE hydrocode. To demonstrate the efficiency of modeling using a sparse cache model we consider detonations in energetic materials.

Sensory Agreement Guides Kinetic Energy Optimization of Arm Movements during Object Manipulation.

PubMed

Farshchiansadegh, Ali; Melendez-Calderon, Alejandro; Ranganathan, Rajiv; Murphey, Todd D; Mussa-Ivaldi, Ferdinando A

2016-04-01

The laws of physics establish the energetic efficiency of our movements. In some cases, like locomotion, the mechanics of the body dominate in determining the energetically optimal course of action. In other tasks, such as manipulation, energetic costs depend critically upon the variable properties of objects in the environment. Can the brain identify and follow energy-optimal motions when these motions require moving along unfamiliar trajectories? What feedback information is required for such optimal behavior to occur? To answer these questions, we asked participants to move their dominant hand between different positions while holding a virtual mechanical system with complex dynamics (a planar double pendulum). In this task, trajectories of minimum kinetic energy were along curvilinear paths. Our findings demonstrate that participants were capable of finding the energy-optimal paths, but only when provided with veridical visual and haptic information pertaining to the object, lacking which the trajectories were executed along rectilinear paths.

Syntheses and characterizations of two new energetic copper–amine-DNANT complexes and their effects on thermal decomposition of RDX

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

Qiu, Qianqian; Xu, Kangzhen, E-mail: xukz@nwu.edu.cn; Department of Chemistry, The Hong Kong University of Science and Technology, Kowloon

Two novel copper complexes of dinitroacetonitrile (DNANT), Cu(NH{sub 3}){sub 4}(DNANT){sub 2} (1) and Cu(en){sub 2}(DNATN){sub 2} (2), have been synthesized for the first time through an unique reaction, and structurally characterized. The single-crystal X-ray structural analysis shows that the Cu{sup 2+} cations in the two complexes share a similar four-coordinated structure, which however does not directly involve the main energetic DNANT{sup −} anion. The differential scanning calorimetry (DSC) study reveals that the two complexes have higher thermal stability and lower sensitivity than the analogous FOX-7 complexes, and exhibit good catalytic action to the decomposition of RDX. - Graphical abstract: Cu(NH{submore » 3}){sub 4}(DNANT){sub 2} (1) and Cu(en){sub 2}(DNATN){sub 2} (2) have been first synthesized through an unique reaction. Cu{sup 2+} ion shares a similar four-coordinated structure in the two complexes. Display Omitted - Highlights: • A new reaction is unexpectedly found, and reaction process was discussed in this work. • Cu(NH{sub 3}){sub 4} (DNANT){sub 2}and Cu(en){sub 2}(DNATN){sub 2} were first synthesized through an unique reaction. • The structures and properties of the two complexes were discussed in detail, and they all present good application performances. • The adjacent amino-hydrazino group in AHDNE exhibits high reactivity. The work is another typical example for the reactivity.« less

Daily School Context of Adolescents' Single Best Friendship and Adjustment.

PubMed

Witkow, Melissa R; Rickert, Nicolette P; Cullen, Laura E

2017-01-01

Research on adolescent best friendships typically focuses on school-based friendships, ignoring important differences between classroom-based and out-of-school friendships. With data from 156 ninth-grade students, many of whom named more than 1 best friend across the 14-day period, the authors examined associations between the daily school context of one's best friendship and adjustment. Benefits of in-grade best friendships were found in academic engagement when a composite was assessed across the 2-week period. Daily findings were more complex and were different between weekends and school days. Out-of-grade best friends were named more frequently on weekends, and on weekend days in which they named an out-of-school best friend participants spent more time with that friend but felt like less of a good student. Implications for our understanding of friendship context and for the measurement of friendship itself are discussed.

Methylene blue binding to DNA with alternating AT base sequence: minor groove binding is favored over intercalation.

PubMed

Rohs, Remo; Sklenar, Heinz

2004-04-01

The results presented in this paper on methylene blue (MB) binding to DNA with AT alternating base sequence complement the data obtained in two former modeling studies of MB binding to GC alternating DNA. In the light of the large amount of experimental data for both systems, this theoretical study is focused on a detailed energetic analysis and comparison in order to understand their different behavior. Since experimental high-resolution structures of the complexes are not available, the analysis is based on energy minimized structural models of the complexes in different binding modes. For both sequences, four different intercalation structures and two models for MB binding in the minor and major groove have been proposed. Solvent electrostatic effects were included in the energetic analysis by using electrostatic continuum theory, and the dependence of MB binding on salt concentration was investigated by solving the non-linear Poisson-Boltzmann equation. We find that the relative stability of the different complexes is similar for the two sequences, in agreement with the interpretation of spectroscopic data. Subtle differences, however, are seen in energy decompositions and can be attributed to the change from symmetric 5'-YpR-3' intercalation to minor groove binding with increasing salt concentration, which is experimentally observed for the AT sequence at lower salt concentration than for the GC sequence. According to our results, this difference is due to the significantly lower non-electrostatic energy for the minor groove complex with AT alternating DNA, whereas the slightly lower binding energy to this sequence is caused by a higher deformation energy of DNA. The energetic data are in agreement with the conclusions derived from different spectroscopic studies and can also be structurally interpreted on the basis of the modeled complexes. The simple static modeling technique and the neglect of entropy terms and of non-electrostatic solute-solvent interactions, which are assumed to be nearly constant for the compared complexes of MB with DNA, seem to be justified by the results.

Multipoint Observations of Energetic Particle Injections and Substorm Activity During a Conjunction Between Magnetospheric Multiscale (MMS) and Van Allen Probes

NASA Astrophysics Data System (ADS)

Turner, D. L.; Fennell, J. F.; Blake, J. B.; Claudepierre, S. G.; Clemmons, J. H.; Jaynes, A. N.; Leonard, T.; Baker, D. N.; Cohen, I. J.; Gkioulidou, M.; Ukhorskiy, A. Y.; Mauk, B. H.; Gabrielse, C.; Angelopoulos, V.; Strangeway, R. J.; Kletzing, C. A.; Le Contel, O.; Spence, H. E.; Torbert, R. B.; Burch, J. L.; Reeves, G. D.

2017-11-01

This study examines multipoint observations during a conjunction between Magnetospheric Multiscale (MMS) and Van Allen Probes on 7 April 2016 in which a series of energetic particle injections occurred. With complementary data from Time History of Events and Macroscale Interactions during Substorms, Geotail, and Los Alamos National Laboratory spacecraft in geosynchronous orbit (16 spacecraft in total), we develop new insights on the nature of energetic particle injections associated with substorm activity. Despite this case involving only weak substorm activity (maximum AE <300 nT) during quiet geomagnetic conditions in steady, below-average solar wind, a complex series of at least six different electron injections was observed throughout the system. Intriguingly, only one corresponding ion injection was clearly observed. All ion and electron injections were observed at <600 keV only. MMS reveals detailed substructure within the largest electron injection. A relationship between injected electrons with energy <60 keV and enhanced whistler mode chorus wave activity is also established from Van Allen Probes and MMS. Drift mapping using a simplified magnetic field model provides estimates of the dispersionless injection boundary locations as a function of universal time, magnetic local time, and L shell. The analysis reveals that at least five electron injections, which were localized in magnetic local time, preceded a larger injection of both electrons and ions across nearly the entire nightside of the magnetosphere near geosynchronous orbit. The larger ion and electron injection did not penetrate to L < 6.6, but several of the smaller electron injections penetrated to L < 6.6. Due to the discrepancy between the number, penetration depth, and complexity of electron versus ion injections, this event presents challenges to the current conceptual models of energetic particle injections.

Surface-induced dissociation: a unique tool for studying energetics and kinetics of the gas-phase fragmentation of large ions

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

Laskin, Julia

2015-01-01

Surface-induced dissociation (SID) is valuable tool for investigating activation and dissociation of large ions in tandem mass spectrometry. This account summarizes key findings from studies of the energetics and mechanisms of complex ion dissociation, in which SID experiments were combined with Rice-Ramsperger-Kassel-Marcus (RRKM) modeling of the experimental data. These studies used time- and collision-energy-resolved SID experiments and SID combined with resonant ejection of selected fragment ions on a specially designed Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). Fast ion activation by collision with a surface combined with the long and variable timescale of a FT-ICR MS is perfectlymore » suited for studying the energetics and dynamics of complex ion dissociation in the gas phase. Modeling of time- and collision-energy-resolved SID enables accurate determination of energy and entropy effects in the dissociation process. It has been demonstrated that entropy effects play an important role in determining the dissociation rates of both covalent and non-covalent bonds in large gaseous ions. SID studies have provided important insights on the competition between charge-directed and charge-remote fragmentation in even-electron peptide ions and the role of charge and radical site on the energetics of the dissociation of odd-electron peptide ions. Furthermore, this work examined factors that affect the strength of non-covalent binding, as well as the competition between covalent and non-covalent bond cleavages and between proton and electron transfer in model systems. Finally, SID studies have been used to understand the factors affecting nucleation and growth of clusters in solution and the gas phase.« less

Probing the Energetics of Dynactin Filament Assembly and the Binding of Cargo Adaptor Proteins Using Molecular Dynamics Simulation and Electrostatics-Based Structural Modeling.

PubMed

Zheng, Wenjun

2017-01-10

Dynactin, a large multiprotein complex, binds with the cytoplasmic dynein-1 motor and various adaptor proteins to allow recruitment and transportation of cellular cargoes toward the minus end of microtubules. The structure of the dynactin complex is built around an actin-like minifilament with a defined length, which has been visualized in a high-resolution structure of the dynactin filament determined by cryo-electron microscopy (cryo-EM). To understand the energetic basis of dynactin filament assembly, we used molecular dynamics simulation to probe the intersubunit interactions among the actin-like proteins, various capping proteins, and four extended regions of the dynactin shoulder. Our simulations revealed stronger intersubunit interactions at the barbed and pointed ends of the filament and involving the extended regions (compared with the interactions within the filament), which may energetically drive filament termination by the capping proteins and recruitment of the actin-like proteins by the extended regions, two key features of the dynactin filament assembly process. Next, we modeled the unknown binding configuration among dynactin, dynein tails, and a number of coiled-coil adaptor proteins (including several Bicaudal-D and related proteins and three HOOK proteins), and predicted a key set of charged residues involved in their electrostatic interactions. Our modeling is consistent with previous findings of conserved regions, functional sites, and disease mutations in the adaptor proteins and will provide a structural framework for future functional and mutational studies of these adaptor proteins. In sum, this study yielded rich structural and energetic information about dynactin and associated adaptor proteins that cannot be directly obtained from the cryo-EM structures with limited resolutions.

Energetics of Intermolecular Hydrogen Bonds in a Hydrophobic Protein Cavity

NASA Astrophysics Data System (ADS)

Liu, Lan; Baergen, Alyson; Michelsen, Klaus; Kitova, Elena N.; Schnier, Paul D.; Klassen, John S.

2014-05-01

This work explores the energetics of intermolecular H-bonds inside a hydrophobic protein cavity. Kinetic measurements were performed on the gaseous deprotonated ions (at the -7 charge state) of complexes of bovine β-lactoglobulin (Lg) and three monohydroxylated analogs of palmitic acid (PA): 3-hydroxypalmitic acid (3-OHPA), 7-hydroxypalmitic acid (7-OHPA), and 16-hydroxypalmitic acid (16-OHPA). From the increase in the activation energy for the dissociation of the (Lg + X-OHPA)7- ions, compared with that of the (Lg + PA)7- ion, it is concluded that the -OH groups of the X-OHPA ligands participate in strong (5 - 11 kcal mol-1) intermolecular H-bonds in the hydrophobic cavity of Lg. The results of molecular dynamics (MD) simulations suggest that the -OH groups of 3-OHPA and 16-OHPA act as H-bond donors and interact with backbone carbonyl oxygens, whereas the -OH group of 7-OHPA acts as both H-bond donor and acceptor with nearby side chains. The capacity for intermolecular H-bonds within the Lg cavity, as suggested by the gas-phase measurements, does not necessarily lead to enhanced binding in aqueous solution. The association constant (Ka) measured for 7-OHPA [(2.3 ± 0.2) × 105 M-1] is similar to the value for the PA [(3.8 ± 0.1) × 105 M-1]; Ka for 3-OHPA [(1.1 ± 0.3) × 106 M-1] is approximately three-times larger, whereas Ka for 16-OHPA [(2.3 ± 0.2) × 104 M-1] is an order of magnitude smaller. Taken together, the results of this study suggest that the energetic penalty to desolvating the ligand -OH groups, which is necessary for complex formation, is similar in magnitude to the energetic contribution of the intermolecular H-bonds.

Assessing hydrodynamic space use of brown trout, Salmo trutta, in a complex flow environment: a return to first principles.

PubMed

Kerr, James R; Manes, Costantino; Kemp, Paul S

2016-11-01

It is commonly assumed that stream-dwelling fish should select positions where they can reduce energetic costs relative to benefits gained and enhance fitness. However, the selection of appropriate hydrodynamic metrics that predict space use is the subject of recent debate and a cause of controversy. This is for three reasons: (1) flow characteristics are often oversimplified, (2) confounding variables are not always controlled and (3) there is limited understanding of the explanatory mechanisms that underpin the biophysical interactions between fish and their hydrodynamic environment. This study investigated the space use of brown trout, Salmo trutta, in a complex hydrodynamic flow field created using an array of different sized vertically oriented cylinders in a large open-channel flume in which confounding variables were controlled. A hydrodynamic drag function (D) based on single-point time-averaged velocity statistics that incorporates the influence of turbulent fluctuations was used to infer the energetic cost of steady swimming. Novel hydrodynamic preference curves were developed and used to assess the appropriateness of D as a descriptor of space use compared with other commonly used metrics. Zones in which performance-enhancing swimming behaviours (e.g. Kármán gaiting, entraining and bow riding) that enable fish to hold position while reducing energetic costs (termed 'specialised behaviours') were identified and occupancy was recorded. We demonstrate that energy conservation strategies play a key role in space use in an energetically taxing environment with the majority of trout groups choosing to frequently occupy areas in which specialised behaviours may be adopted or by selecting low-drag regions. © 2016. Published by The Company of Biologists Ltd.

Multipoint Observations of Energetic Particle Injections and Substorm Activity During a Conjunction Between Magnetospheric Multiscale (MMS) and Van Allen Probes

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

Turner, Drew L.; Fennell, J. F.; Blake, J. B.

Here, this study examines multipoint observations during a conjunction between Magnetospheric Multiscale (MMS) and Van Allen Probes on 7 April 2016 in which a series of energetic particle injections occurred. With complementary data from Time History of Events and Macroscale Interactions during Substorms, Geotail, and Los Alamos National Laboratory spacecraft in geosynchronous orbit (16 spacecraft in total), we develop new insights on the nature of energetic particle injections associated with substorm activity. Despite this case involving only weak substorm activity (maximum AE <300 nT) during quiet geomagnetic conditions in steady, below-average solar wind, a complex series of at least sixmore » different electron injections was observed throughout the system. Intriguingly, only one corresponding ion injection was clearly observed. All ion and electron injections were observed at <600 keV only. MMS reveals detailed substructure within the largest electron injection. A relationship between injected electrons with energy <60 keV and enhanced whistler mode chorus wave activity is also established from Van Allen Probes and MMS. Drift mapping using a simplified magnetic field model provides estimates of the dispersionless injection boundary locations as a function of universal time, magnetic local time, and L shell. The analysis reveals that at least five electron injections, which were localized in magnetic local time, preceded a larger injection of both electrons and ions across nearly the entire nightside of the magnetosphere near geosynchronous orbit. The larger ion and electron injection did not penetrate to L < 6.6, but several of the smaller electron injections penetrated to L < 6.6. Due to the discrepancy between the number, penetration depth, and complexity of electron versus ion injections, this event presents challenges to the current conceptual models of energetic particle injections.« less

Multipoint Observations of Energetic Particle Injections and Substorm Activity During a Conjunction Between Magnetospheric Multiscale (MMS) and Van Allen Probes

DOE PAGES

Turner, Drew L.; Fennell, J. F.; Blake, J. B.; ...

2017-09-25

Here, this study examines multipoint observations during a conjunction between Magnetospheric Multiscale (MMS) and Van Allen Probes on 7 April 2016 in which a series of energetic particle injections occurred. With complementary data from Time History of Events and Macroscale Interactions during Substorms, Geotail, and Los Alamos National Laboratory spacecraft in geosynchronous orbit (16 spacecraft in total), we develop new insights on the nature of energetic particle injections associated with substorm activity. Despite this case involving only weak substorm activity (maximum AE <300 nT) during quiet geomagnetic conditions in steady, below-average solar wind, a complex series of at least sixmore » different electron injections was observed throughout the system. Intriguingly, only one corresponding ion injection was clearly observed. All ion and electron injections were observed at <600 keV only. MMS reveals detailed substructure within the largest electron injection. A relationship between injected electrons with energy <60 keV and enhanced whistler mode chorus wave activity is also established from Van Allen Probes and MMS. Drift mapping using a simplified magnetic field model provides estimates of the dispersionless injection boundary locations as a function of universal time, magnetic local time, and L shell. The analysis reveals that at least five electron injections, which were localized in magnetic local time, preceded a larger injection of both electrons and ions across nearly the entire nightside of the magnetosphere near geosynchronous orbit. The larger ion and electron injection did not penetrate to L < 6.6, but several of the smaller electron injections penetrated to L < 6.6. Due to the discrepancy between the number, penetration depth, and complexity of electron versus ion injections, this event presents challenges to the current conceptual models of energetic particle injections.« less

Quantum Computing since Democritus

NASA Astrophysics Data System (ADS)

Aaronson, Scott

2013-03-01

1. Atoms and the void; 2. Sets; 3. Gödel, Turing, and friends; 4. Minds and machines; 5. Paleocomplexity; 6. P, NP, and friends; 7. Randomness; 8. Crypto; 9. Quantum; 10. Quantum computing; 11. Penrose; 12. Decoherence and hidden variables; 13. Proofs; 14. How big are quantum states?; 15. Skepticism of quantum computing; 16. Learning; 17. Interactive proofs and more; 18. Fun with the Anthropic Principle; 19. Free will; 20. Time travel; 21. Cosmology and complexity; 22. Ask me anything.

Reinterpretaion of the friendship paradox

NASA Astrophysics Data System (ADS)

Fu, Jingcheng; Wu, Jianliang

The friendship paradox (FP) is a sociological phenomenon stating that most people have fewer friends than their friends do. It is to say that in a social network, the number of friends that most individuals have is smaller than the average number of friends of friends. This has been verified by Feld. We call this interpreting method mean value version. But is it the best choice to portray the paradox? In this paper, we propose a probability method to reinterpret this paradox, and we illustrate that the explanation using our method is more persuasive. An individual satisfies the FP if his (her) randomly chosen friend has more friends than him (her) with probability not less than 1/2. Comparing the ratios of nodes satisfying the FP in networks, rp, we can see that the probability version is stronger than the mean value version in real networks both online and offline. We also show some results about the effects of several parameters on rp in random network models. Most importantly, rp is a quadratic polynomial of the power law exponent γ in Price model, and rp is higher when the average clustering coefficient is between 0.4 and 0.5 in Petter-Beom (PB) model. The introduction of the probability method to FP can shed light on understanding the network structure in complex networks especially in social networks.

Hydrogen molecules inside fullerene C70: quantum dynamics, energetics, maximum occupancy, and comparison with C60.

PubMed

Sebastianelli, Francesco; Xu, Minzhong; Bacić, Zlatko; Lawler, Ronald; Turro, Nicholas J

2010-07-21

Recent synthesis of the endohedral complexes of C(70) and its open-cage derivative with one and two H(2) molecules has opened the path for experimental and theoretical investigations of the unique dynamic, spectroscopic, and other properties of systems with multiple hydrogen molecules confined inside a nanoscale cavity. Here we report a rigorous theoretical study of the dynamics of the coupled translational and rotational motions of H(2) molecules in C(70) and C(60), which are highly quantum mechanical. Diffusion Monte Carlo (DMC) calculations were performed for up to three para-H(2) (p-H(2)) molecules encapsulated in C(70) and for one and two p-H(2) molecules inside C(60). These calculations provide a quantitative description of the ground-state properties, energetics, and the translation-rotation (T-R) zero-point energies (ZPEs) of the nanoconfined p-H(2) molecules and of the spatial distribution of two p-H(2) molecules in the cavity of C(70). The energy of the global minimum on the intermolecular potential energy surface (PES) is negative for one and two H(2) molecules in C(70) but has a high positive value when the third H(2) is added, implying that at most two H(2) molecules can be stabilized inside C(70). By the same criterion, in the case of C(60), only the endohedral complex with one H(2) molecule is energetically stable. Our results are consistent with the fact that recently both (H(2))(n)@C(70) (n = 1, 2) and H(2)@C(60) were prepared, but not (H(2))(3)@C(70) or (H(2))(2)@C(60). The ZPE of the coupled T-R motions, from the DMC calculations, grows rapidly with the number of caged p-H(2) molecules and is a significant fraction of the well depth of the intermolecular PES, 11% in the case of p-H(2)@C(70) and 52% for (p-H(2))(2)@C(70). Consequently, the T-R ZPE represents a major component of the energetics of the encapsulated H(2) molecules. The inclusion of the ZPE nearly doubles the energy by which (p-H(2))(3)@C(70) is destabilized and increases by 66% the energetic destabilization of (p-H(2))(2)@C(60). For these reasons, the T-R ZPE has to be calculated accurately and taken into account for reliable theoretical predictions regarding the stability of the endohedral fullerene complexes with hydrogen molecules and their maximum H(2) content.

Binge drinking, marijuana use, and friendships: the relationship between similar and dissimilar usage and friendship quality.

PubMed

Boman, John H; Stogner, John; Miller, Bryan Lee

2013-01-01

While it is commonly understood that the substance use of peers influences an individual's substance use, much less is understood about the interplay between substance use and friendship quality. Using a sample of 2,148 emerging adults nested within 1,074 dyadic friendships, this study separately investigates how concordance and discordance in binge drinking and marijuana use between friends is related to each friend's perceptions of friendship quality. Because "friendship quality" is a complex construct, we employ a measure containing five sub-elements--companionship, a lack of conflict, willingness to help a friend, relationship security, and closeness. Results for both binge drinking and marijuana use reveal that individuals in friendship pairs who are concordant in their substance use perceive significantly higher perceptions of friendship quality than individuals in dyads who are dissimilar in substance use. Specifically, concordant binge drinkers estimate significantly higher levels of companionship, relationship security, and willingness to help their friend than concordant non-users, discordant users, and discordant non-users. However, the highest amount of conflict in friendships is found when both friends engage in binge drinking and marijuana use. Several interpretations of these findings are discussed. Overall, concordance between friends' binge drinking and marijuana use appears to help some elements of friendship quality and harm others.

When You Operate on Friends and Relatives: Results of a Survey among Surgeons.

PubMed

Knuth, Jurgen; Bulian, Dirk Rolf; Ansorg, Jörg; Büchler, Peter

2017-01-01

We designed a questionnaire to collect data on surgeons' views and experiences of operating on friends or relatives. A link to a 38-item online survey was sent to all 16,849 members of the Professional Board of German Surgeons (Bund Deutscher Chirurgen, BDC) several times. Standard interview software was used. The questionnaire collected a wide variety of information concerning how surgeons have experienced, think about, and deal with the situation when they operate on friends or relatives. Of the 16,849 BDC members notified of the survey, 1,643 completed the questionnaires (9.8%). Of these, 1,275 (77.6%) had previously performed surgery on friends or relatives. Overall, the surgeons willingly accepted doing so without experiencing any difficulties. However, the surgeons frequently used different techniques when operating on friends and relatives (123 [10%] when self-assessed compared to 527 [35%] when observed by others). Out of the whole sample, 506 (30.8%) would appreciate having a guideline or ethical code and 370 (41.2%) of those who have not yet operated on friends and relatives would like to have such an ethical code. Most of the surgeons who responded accepted the task of operating on friends or relatives. Performing surgery on friends or relatives was a complex matter because objectivity was not guaranteed. Negative implications on personal relationships were rare. We recommend that this matter should be well considered and discussed with the patient and an ethical guideline or code should be created. © 2017 S. Karger AG, Basel.

When You Operate on Friends and Relatives: Results of a Survey among Surgeons

PubMed Central

Knuth, Jurgen; Bulian, Dirk Rolf; Ansorg, Jörg; Büchler, Peter

2017-01-01

Objective We designed a questionnaire to collect data on surgeons' views and experiences of operating on friends or relatives. Subjects and Methods A link to a 38-item online survey was sent to all 16,849 members of the Professional Board of German Surgeons (Bund Deutscher Chirurgen, BDC) several times. Standard interview software was used. The questionnaire collected a wide variety of information concerning how surgeons have experienced, think about, and deal with the situation when they operate on friends or relatives. Results Of the 16,849 BDC members notified of the survey, 1,643 completed the questionnaires (9.8%). Of these, 1,275 (77.6%) had previously performed surgery on friends or relatives. Overall, the surgeons willingly accepted doing so without experiencing any difficulties. However, the surgeons frequently used different techniques when operating on friends and relatives (123 [10%] when self-assessed compared to 527 [35%] when observed by others). Out of the whole sample, 506 (30.8%) would appreciate having a guideline or ethical code and 370 (41.2%) of those who have not yet operated on friends and relatives would like to have such an ethical code. Conclusion Most of the surgeons who responded accepted the task of operating on friends or relatives. Performing surgery on friends or relatives was a complex matter because objectivity was not guaranteed. Negative implications on personal relationships were rare. We recommend that this matter should be well considered and discussed with the patient and an ethical guideline or code should be created. PMID:28114131

Particle Environment Package (PEP) for the ESA JUICE mission

NASA Astrophysics Data System (ADS)

Barabash, Stas; Brandt, Pontus; Wurz, Peter; PEP Team

2016-10-01

PEP is a suite of six (6) sensors arranged in 4 units to measure charged and neutral particles in the Jupiter magnetospheres and at the moons to answer four overarching science questions:1. How does the corotating magnetosphere of Jupiter interact with the complex and diverse environment of Ganymede?2. How does the rapidly rotating magnetosphere of Jupiter interact with the seemingly inert Callisto?3. What are the governing mechanisms and their global impacts of release of material into the Jovian magnetosphere from seemingly inert Europa and active Io?4. How do internal and solar wind drivers cause such energetic, time variable and multi-scale phenomena in the steadily rotating giant magnetosphere of Jupiter?PEP measures positive and negative ions, electrons, exospheric neutral gas, thermal plasma and energetic neutral atoms present in all domains of the Jupiter system over nine decades of energy from < 0.001 eV to > 1 MeV with full angular coverage.PEP provides instantaneous measurements of 3D flow of the ion plasma and composition to understand the magnetosphere and magnetosphere-moon interactions. It also measures instantaneously 3D electron plasma to investigate auroral processes at the moon and Jupiter. Measurements of the angular distributions of energetic electrons at sub-second resolution probe the acceleration mechanisms and magnetic field topology and boundaries.PEP combines global imaging via remote sensing using energetic neutral atoms (ENA) with in-situ measurements and performs global imaging of Europa/Io tori and magnetosphere combined with energetic ion measurements. Using low energy ENAs originating from the particle - surface interaction PEP investigate space weathering of the icy moons by precipitation particles. PEP will first-ever directly sample of the exospheres of Europa, Ganymede, and Callisto with extremely high mass resolution (M/ΔM > 1100).The PEP sensors are (1) an ion mass analyzer, (2) an electron spectrometer, (3) a low energy ENA imager, (4) a high energy ENA and energetic ions imager, (5) an energetic electron sensor, and (6) a neutral gas and ions mass spectrometer.

Energetic ion leakage from foreshock transient cores

NASA Astrophysics Data System (ADS)

Liu, Terry Z.; Angelopoulos, Vassilis; Hietala, Heli

2017-07-01

Earth's foreshock is filled with backstreaming particles that can interact with the ambient solar wind and its discontinuities to form foreshock transients. Many foreshock transients have a core with low dynamic pressure that can significantly perturb the bow shock and the magnetosphere-ionosphere system. Foreshock transients have also been recently recognized as sites of particle acceleration, which may be important for seeding the parent shock with energetic particles. A relevant step of this seeding would be energetic ion leakage into the surrounding foreshock environment. On the other hand, such leakage would also suppress the energetic particle flux contrast across foreshock transients' boundaries masking their perceived contribution to ion energization. To further examine this hypothesis of ion leakage, we report on multipoint case studies of three foreshock transient events selected from a large database. The cases were selected to exemplify, in increasing complexity, the nature and consequences of energetic ion leakage. Ion energy dispersion, observed upstream and/or downstream of the foreshock transients, is explained with a simple, ballistic model of ions leaking from the foreshock transients. Larger energies are required for leaked ions to reach the spacecraft as the distance between the transient and spacecraft increases. Our model, which explains well the observed ion energy dispersion and velocity distributions, can also be used to reveal the shape of the foreshock transients in three dimensions. Our results suggest that ion leakage from foreshock transient cores needs to be accounted for both in statistical studies and in global models of ion acceleration under quasi-parallel foreshock conditions.

Energetic-Energetic Cocrystals of Diacetone Diperoxide (DADP): Dramatic and Divergent Sensitivity Modifications via Cocrystallization.

PubMed

Landenberger, Kira B; Bolton, Onas; Matzger, Adam J

2015-04-22

Here we report a series of energetic-energetic cocrystals that incorporate the primary explosive diacetone diperoxide (DADP) with a series of trihalotrinitrobenzene explosives: 1:1 DADP/1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB), 1:1 DADP/1,3,5-tribromo-2,4,6-trinitrobenzene (TBTNB), and 1:1 DADP/1,3,5-triiodo-2,4,6-trinitrobenzene (TITNB). Acetone peroxides are attractive for their inexpensive and facile synthesis, but undesirable properties such as poor stability, intractably high sensitivity and low density, an indicator for low explosive power, have limited their application. Here through cocrystallization the density, oxygen balance, and stability of DADP are dramatically improved. Regarding sensitivity, in the case of the DADP/TCTNB cocrystal, the high impact sensitivity of DADP is retained by the cocrystal, making it a denser and less volatile form of DADP that remains viable as a primary explosive. Conversely, the DADP/TITNB cocrystal features impact sensitivity that is greatly reduced relative to both pure DADP and pure TITNB, demonstrating for the first time an energetic cocrystal that is less sensitive to impact than either of its pure components. This dramatic difference in cocrystal sensitivities may stem from the significantly different halogen-peroxide interactions seen in each cocrystal structure. These results highlight how sensitivity is defined by complex relationships between inherent bond strengths and solid-state properties, and cocrystal series such as that presented here provide a powerful experimental platform to probe this relationship.

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.

Probing the energetics of dissociation of carbonic anhydrase-ligand complexes in the gas phase.

PubMed Central

Gao, J; Wu, Q; Carbeck, J; Lei, Q P; Smith, R D; Whitesides, G M

1999-01-01

This paper describes the use of electrospray ionization-Fourier transform ion cyclotron mass spectrometry (ESI-FTICR-MS) to study the relative stabilities of noncovalent complexes of carbonic anhydrase II (CAII, EC 4.2.1.1) and benzenesulfonamide inhibitors in the gas phase. Sustained off-resonance irradiation collision-induced dissociation (SORI-CID) was used to determine the energetics of dissociation of these CAII-sulfonamide complexes in the gas phase. When two molecules of a benzenesulfonamide (1) were bound simultaneously to one molecule of CAII, one of them was found to exhibit significantly weaker binding (DeltaE50 = 0.4 V, where E50 is defined as the amplitude of sustained off-resonance irradiation when 50% of the protein-ligand complexes are dissociated). In solution, the benzenesulfonamide group coordinates as an anion to a Zn(II) ion bound at the active site of the enzyme. The gas phase stability of the complex with the weakly bound inhibitor was the same as that of the inhibitor complexed with apoCAII (i.e., CAII with the Zn(II) ion removed from the binding site). These results indicate that specific interactions between the sulfonamide group on the inhibitor and the Zn(II) ion on CAII were preserved in the gas phase. Experiments also showed a higher gas phase stability for the complex of para-NO2-benzenesulfonamide-CAII than that for ortho-NO2-benzenesulfonamide-CAII complex. This result further suggests that steric interactions of the inhibitors with the binding pocket of CAII parallel those in solution. Overall, these results are consistent with the hypothesis that CAII retains, at least partially, the structure of its binding pocket in the gas phase on the time scale (seconds to minutes) of the ESI-FTICR measurements. PMID:10354450

Structural basis for binding of aurora-AG198N- INCENP complex: MD simulations and free energy calculations.

PubMed

Tanneeru, Karunakar; Guruprasad, Lalitha

2013-11-01

Aurora-A, B and C are non-receptor serine/threonine kinases in Homo sapiens. In spite of high similarity in their sequences, they possess distinct binding partners. These kinases play an important role in cell division and overexpressed in certain cancers. It has been demonstrated that Gly198 in Aurora-A kinase is responsible for its basal kinase activity, the mutation G198N transforms Aurora-A to Aurora-B like function and localization by binding to Inner centromere protein (INCENP). The molecular mechanisms, structural determinants and the binding energetics of the Aurora-A - INCENP complex owing to a single amino acid G198N mutation are not studied. Therefore, we have docked INCENP into human Aurora-A kinase, mutated Gly198 to Asn, Leu and Ala. The wild type and mutant Aurora-A - INCENP complexes were subjected to 40 ns molecular dynamics (MD) simulations. The Asn198 is located in the amphipathic cavity comprising Leu869(IN), Glu868(IN), Thr872(IN), Tyr197(AurA) and Tyr199(AurA) and the interactions mediated via hydrogen bonds are important to stabilize the Aurora-A(G198N) - INCENP complex. The fluctuations in the secondary structural elements and the solvent accessible surface area of all the four complexes during the MD simulations were studied. We calculated the binding free energy upon mutation in the three mutant complexes. The Aurora-A(G198N) - INCENP complex with hydrophilic amino acid mutation has the negative free energy of solvation indicating favorable interactions with INCENP. Our results provide the structural basis and energetics of the human Aurora-A(G198N) - INCENP complex.

The radiation environment on the surface of Mars - Summary of model calculations and comparison to RAD data

NASA Astrophysics Data System (ADS)

Matthiä, Daniel; Hassler, Donald M.; de Wet, Wouter; Ehresmann, Bent; Firan, Ana; Flores-McLaughlin, John; Guo, Jingnan; Heilbronn, Lawrence H.; Lee, Kerry; Ratliff, Hunter; Rios, Ryan R.; Slaba, Tony C.; Smith, Michael; Stoffle, Nicholas N.; Townsend, Lawrence W.; Berger, Thomas; Reitz, Günther; Wimmer-Schweingruber, Robert F.; Zeitlin, Cary

2017-08-01

The radiation environment at the Martian surface is, apart from occasional solar energetic particle events, dominated by galactic cosmic radiation, secondary particles produced in their interaction with the Martian atmosphere and albedo particles from the Martian regolith. The highly energetic primary cosmic radiation consists mainly of fully ionized nuclei creating a complex radiation field at the Martian surface. This complex field, its formation and its potential health risk posed to astronauts on future manned missions to Mars can only be fully understood using a combination of measurements and model calculations. In this work the outcome of a workshop held in June 2016 in Boulder, CO, USA is presented: experimental results from the Radiation Assessment Detector of the Mars Science Laboratory are compared to model results from GEANT4, HETC-HEDS, HZETRN, MCNP6, and PHITS. Charged and neutral particle spectra and dose rates measured between 15 November 2015 and 15 January 2016 and model results calculated for this time period are investigated.

Fundamental Challenges in Mechanistic Enzymology: Progress toward Understanding the Rate Enhancements of Enzymes

PubMed Central

Herschlag, Daniel; Natarajan, Aditya

2013-01-01

Enzymes are remarkable catalysts that lie at the heart of biology, accelerating chemical reactions to an astounding extent with extraordinary specificity. Enormous progress in understanding the chemical basis of enzymatic transformations and the basic mechanisms underlying rate enhancements over the past decades is apparent. Nevertheless, it has been difficult to achieve a quantitative understanding of how the underlying mechanisms account for the energetics of catalysis, because of the complexity of enzyme systems and the absence of underlying energetic additivity. We review case studies from our own work that illustrate the power of precisely defined and clearly articulated questions when dealing with such complex and multi-faceted systems, and we also use this approach to evaluate our current ability to design enzymes. We close by highlighting a series of questions that help frame some of what remains to be understood, and we encourage the reader to define additional questions and directions that will deepen and broaden our understanding of enzymes and their catalysis. PMID:23488725

α-Cyclodextrin dimer complexes of dopamine and levodopa derivatives to assess drug delivery to the central nervous system: ADME and molecular docking studies

PubMed Central

Shityakov, Sergey; Broscheit, Jens; Förster, Carola

2012-01-01

This paper attempts to predict and emphasize molecular interactions of dopamine, levodopa, and their derivatives (Dopimid compounds) containing 2-phenyl-imidazopyridine moiety with the α-cyclodextrin dimer in order to assess and improve drug delivery to the central nervous system. The molecular docking method is used to determine the energetic profiles, hydrogen bond formation, and hydrophobic effect of 14 host–guest complexes. The results show that the “chemical branching” represented by additional ethyl-acetate residue is energetically unfavorable and promotes a conformational shift due to the high root mean square deviation levels. This phenomenon is characterized by a low number of H-bonds and a significant decrease of the host–guest hydrophobic potential surface. Finally, the overall docking procedure presents a powerful rationale for screening and analyzing various sets of promising drug-like chemical compounds in the fields of supramolecular chemistry, molecular sensing, synthetic receptors, and nanobiotechnology. PMID:22811606

Fundamental challenges in mechanistic enzymology: progress toward understanding the rate enhancements of enzymes.

PubMed

Herschlag, Daniel; Natarajan, Aditya

2013-03-26

Enzymes are remarkable catalysts that lie at the heart of biology, accelerating chemical reactions to an astounding extent with extraordinary specificity. Enormous progress in understanding the chemical basis of enzymatic transformations and the basic mechanisms underlying rate enhancements over the past decades is apparent. Nevertheless, it has been difficult to achieve a quantitative understanding of how the underlying mechanisms account for the energetics of catalysis, because of the complexity of enzyme systems and the absence of underlying energetic additivity. We review case studies from our own work that illustrate the power of precisely defined and clearly articulated questions when dealing with such complex and multifaceted systems, and we also use this approach to evaluate our current ability to design enzymes. We close by highlighting a series of questions that help frame some of what remains to be understood, and we encourage the reader to define additional questions and directions that will deepen and broaden our understanding of enzymes and their catalysis.

The complex nature of storm-time ion dynamics: Transport and local acceleration

DOE PAGES

Denton, M. H.; Reeves, G. D.; Thomsen, M. F.; ...

2016-09-29

Data from the Van Allen Probes Helium, Oxygen, Proton, and Electron (HOPE) spectrometers reveal hitherto unresolved spatial structure and dynamics in ion populations. Complex regions of O + dominance, at energies from a few eV to >10 keV, are observed throughout the magnetosphere. Isolated regions on the dayside that are rich in energetic O + might easily be interpreted as strong energization of ionospheric plasma. In this paper, we demonstrate, however, that both the energy spectrum and the limited magnetic local time extent of these features can be explained by energy-dependent drift of particles injected on the nightside 24 hmore » earlier. Particle tracing simulations show that the energetic O + can originate in the magnetotail, not in the ionosphere. Finally, enhanced wave activity is colocated with the heavy ion-rich plasma, and we further conclude that the waves were not a source of free energy for accelerating ionospheric plasma but rather the consequence of the arrival of substorm-injected plasma.« less

Structure of a Water Monolayer on the Anatase TiO2(101) Surface

NASA Astrophysics Data System (ADS)

Patrick, Christopher E.; Giustino, Feliciano

2014-07-01

Titanium dioxide (TiO2) plays a central role in the study of artificial photosynthesis, owing to its ability to perform photocatalytic water splitting. Despite over four decades of intense research efforts in this area, there is still some debate over the nature of the first water monolayer on the technologically relevant anatase TiO2(101) surface. In this work, we use first-principles calculations to reverse engineer the experimental high-resolution x-ray photoelectron spectra measured for this surface by Walle et al. [J. Phys. Chem. C 115, 9545 (2011)] and find evidence supporting the existence of a mix of dissociated and molecular water in the first monolayer. Using both semilocal and hybrid functional calculations, we revise the current understanding of the adsorption energetics by showing that the energetic cost of water dissociation is reduced via the formation of a hydrogen-bonded hydroxyl-water complex. We also show that such a complex can provide an explanation of an unusual superstructure observed in high-resolution scanning tunneling microscopy experiments.

Using a voice to put a name to a face: the psycholinguistics of proper name comprehension.

PubMed

Barr, Dale J; Jackson, Laura; Phillips, Isobel

2014-02-01

We propose that hearing a proper name (e.g., Kevin) in a particular voice serves as a compound memory cue that directly activates representations of a mutually known target person, often permitting reference resolution without any complex computation of shared knowledge. In a referential communication study, pairs of friends played a communication game, in which we monitored the eyes of one friend (the addressee) while he or she sought to identify the target person, in a set of four photos, on the basis of a name spoken aloud. When the name was spoken by a friend, addressees rapidly identified the target person, and this facilitation was independent of whether the friend was articulating a message he or she had designed versus one from a third party with whom the target person was not shared. Our findings suggest that the comprehension system takes advantage of regularities in the environment to minimize effortful computation about who knows what.

Persistent and energetic bottom-trapped topographic Rossby waves observed in the southern South China Sea.

PubMed

Shu, Yeqiang; Xue, Huijie; Wang, Dongxiao; Chai, Fei; Xie, Qiang; Cai, Shuqun; Chen, Rongyu; Chen, Ju; Li, Jian; He, Yunkai

2016-04-14

Energetic fluctuations with periods of 9-14 days below a depth of 1400 m were observed in the southern South China Sea (SCS) from 5 years of direct measurements. We interpreted such fluctuations as topographic Rossby waves (TRWs) because they obey the dispersion relation. The TRWs persisted from May 24, 2009 to August 23, 2013, and their bottom current speed with a maximum of ~10 cm/s was one order of magnitude greater than the mean current and comparable to the tidal currents near the bottom. The bottom-trapped TRWs had an approximate trapping depth of 325 m and reference wavelength of ~82 km, which were likely excited by eddies above. Upper layer current speed that peaked approximately every 2 months could offer the energy sources for the persistent TRWs in the southern SCS. Energetic bottom-trapped TRWs may have a comparable role in deep circulation to tides in areas with complex topography.

Persistent and energetic bottom-trapped topographic Rossby waves observed in the southern South China Sea

PubMed Central

Shu, Yeqiang; Xue, Huijie; Wang, Dongxiao; Chai, Fei; Xie, Qiang; Cai, Shuqun; Chen, Rongyu; Chen, Ju; Li, Jian; He, Yunkai

2016-01-01

Energetic fluctuations with periods of 9–14 days below a depth of 1400 m were observed in the southern South China Sea (SCS) from 5 years of direct measurements. We interpreted such fluctuations as topographic Rossby waves (TRWs) because they obey the dispersion relation. The TRWs persisted from May 24, 2009 to August 23, 2013, and their bottom current speed with a maximum of ~10 cm/s was one order of magnitude greater than the mean current and comparable to the tidal currents near the bottom. The bottom-trapped TRWs had an approximate trapping depth of 325 m and reference wavelength of ~82 km, which were likely excited by eddies above. Upper layer current speed that peaked approximately every 2 months could offer the energy sources for the persistent TRWs in the southern SCS. Energetic bottom-trapped TRWs may have a comparable role in deep circulation to tides in areas with complex topography. PMID:27075644

The isolated voltage sensing domain of the Shaker potassium channel forms a voltage-gated cation channel.

PubMed

Zhao, Juan; Blunck, Rikard

2016-10-06

Domains in macromolecular complexes are often considered structurally and functionally conserved while energetically coupled to each other. In the modular voltage-gated ion channels the central ion-conducting pore is surrounded by four voltage sensing domains (VSDs). Here, the energetic coupling is mediated by interactions between the S4-S5 linker, covalently linking the domains, and the proximal C-terminus. In order to characterize the intrinsic gating of the voltage sensing domain in the absence of the pore domain, the Shaker Kv channel was truncated after the fourth transmembrane helix S4 (Shaker-iVSD). Shaker-iVSD showed significantly altered gating kinetics and formed a cation-selective ion channel with a strong preference for protons. Ion conduction in Shaker-iVSD developed despite identical primary sequence, indicating an allosteric influence of the pore domain. Shaker-iVSD also displays pronounced 'relaxation'. Closing of the pore correlates with entry into relaxation suggesting that the two processes are energetically related.

Eruptive event generator based on the Gibson-Low magnetic configuration

NASA Astrophysics Data System (ADS)

Borovikov, D.; Sokolov, I. V.; Manchester, W. B.; Jin, M.; Gombosi, T. I.

2017-08-01

Coronal mass ejections (CMEs), a kind of energetic solar eruptions, are an integral subject of space weather research. Numerical magnetohydrodynamic (MHD) modeling, which requires powerful computational resources, is one of the primary means of studying the phenomenon. With increasing accessibility of such resources, grows the demand for user-friendly tools that would facilitate the process of simulating CMEs for scientific and operational purposes. The Eruptive Event Generator based on Gibson-Low flux rope (EEGGL), a new publicly available computational model presented in this paper, is an effort to meet this demand. EEGGL allows one to compute the parameters of a model flux rope driving a CME via an intuitive graphical user interface. We provide a brief overview of the physical principles behind EEGGL and its functionality. Ways toward future improvements of the tool are outlined.

Copyright Renewal for Libraries: Seven Steps toward a User-Friendly Law

ERIC Educational Resources Information Center

Smith, Kevin L.

2010-01-01

Copyright law is a source of a great deal of bewilderment and frustration to academic librarians. Beyond the basics of copyright protection and fair use, most librarians struggle to grasp the complexity of the law and the roadblocks it presents to access and use. This article attempts to elucidate some of those complexities by suggesting seven…

You've Come a Long Way, Baby, but...

ERIC Educational Resources Information Center

Fayen, Emily Gallup

An online library system is an example of a complex computer system in that it supports a variety of users, both patrons and staff, and is made up of many intricate programs with complex relationships among them. Certain features are essential to a user friendly system: (1) users cannot get lost in the system; (2) users cannot enter illegal…

Complex of technologies and prototype systems for eco-friendly shutdown of the power-generating, process, capacitive, and transport equipment

NASA Astrophysics Data System (ADS)

Smorodin, A. I.; Red'kin, V. V.; Frolov, Y. D.; Korobkov, A. A.; Kemaev, O. V.; Kulik, M. V.; Shabalin, O. V.

2015-07-01

A set of technologies and prototype systems for eco-friendly shutdown of the power-generating, process, capacitive, and transport equipment is offered. The following technologies are regarded as core technologies for the complex: cryogenic technology nitrogen for displacement of hydrogen from the cooling circuit of turbine generators, cryo blasting of the power units by dioxide granules, preservation of the shutdown power units by dehydrated air, and dismantling and severing of equipment and structural materials of power units. Four prototype systems for eco-friendly shutdown of the power units may be built on the basis of selected technologies: Multimode nitrogen cryogenic system with four subsystems, cryo blasting system with CO2 granules for thermal-mechanical and electrical equipment of power units, and compressionless air-drainage systems for drying and storage of the shutdown power units and cryo-gas system for general severing of the steam-turbine power units. Results of the research and pilot and demonstration tests of the operational units of the considered technological systems allow applying the proposed technologies and systems in the prototype systems for shutdown of the power-generating, process, capacitive, and transport equipment.

Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H-SiC.

PubMed

Igumbor, E; Olaniyan, O; Mapasha, R E; Danga, H T; Omotoso, E; Meyer, W E

2018-05-10

Electrically active induced energy levels in semiconductor devices could be beneficial to the discovery of an enhanced p or n-type semiconductor. Nitrogen (N) implanted into 4H-SiC is a high energy process that produced high defect concentrations which could be removed during dopant activation annealing. On the other hand, boron (B) substituted for silicon in SiC causes a reduction in the number of defects. This scenario leads to a decrease in the dielectric properties and induced deep donor and shallow acceptor levels. Complexes formed by the N, such as the nitrogen-vacancy centre, have been reported to play a significant role in the application of quantum bits. In this paper, results of charge states thermodynamic transition level of the N and B vacancy-complexes in 4H-SiC are presented. We explore complexes where substitutional N[Formula: see text]/N[Formula: see text] or B[Formula: see text]/B[Formula: see text] sits near a Si (V[Formula: see text]) or C (V[Formula: see text]) vacancy to form vacancy-complexes (N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text] and B[Formula: see text]V[Formula: see text]). The energies of formation of the N related vacancy-complexes showed the N[Formula: see text]V[Formula: see text] to be energetically stable close to the valence band maximum in its double positive charge state. The N[Formula: see text]V[Formula: see text] is more energetically stable in the double negative charge state close to the conduction band minimum. The N[Formula: see text]V[Formula: see text] on the other hand, induced double donor level and the N[Formula: see text]V[Formula: see text] induced a double acceptor level. For B related complexes, the B[Formula: see text]V[Formula: see text] and B[Formula: see text]V[Formula: see text] were energetically stable in their single positive charge state close to the valence band maximum. As the Fermi energy is varied across the band gap, the neutral and single negative charge states of the B[Formula: see text]V[Formula: see text] become more stable at different energy levels. B and N related complexes exhibited charge state controlled metastability behaviour.

Apraxia

MedlinePlus

... important for people with aprexia. To help with communication, family and friends should: Avoid giving complex directions. Use simple phrases to avoid misunderstandings. Speak in a normal tone of ... communication aids, if possible, depending on the person and ...

Dissection of a nuclear localization signal.

PubMed

Hodel, M R; Corbett, A H; Hodel, A E

2001-01-12

The regulated process of protein import into the nucleus of a eukaryotic cell is mediated by specific nuclear localization signals (NLSs) that are recognized by protein import receptors. This study seeks to decipher the energetic details of NLS recognition by the receptor importin alpha through quantitative analysis of variant NLSs. The relative importance of each residue in two monopartite NLS sequences was determined using an alanine scanning approach. These measurements yield an energetic definition of a monopartite NLS sequence where a required lysine residue is followed by two other basic residues in the sequence K(K/R)X(K/R). In addition, the energetic contributions of the second basic cluster in a bipartite NLS ( approximately 3 kcal/mol) as well as the energy of inhibition of the importin alpha importin beta-binding domain ( approximately 3 kcal/mol) were also measured. These data allow the generation of an energetic scale of nuclear localization sequences based on a peptide's affinity for the importin alpha-importin beta complex. On this scale, a functional NLS has a binding constant of approximately 10 nm, whereas a nonfunctional NLS has a 100-fold weaker affinity of 1 microm. Further correlation between the current in vitro data and in vivo function will provide the foundation for a comprehensive quantitative model of protein import.

Probing the Energetics of Antigen-Antibody Recognition by Titration Microcalorimetry

PubMed

Jelesarov; Leder; Bosshard

1996-06-01

Our understanding of the energetics that govern antigen-antibody recognition lags behind the increasingly rapid accumulation of structural information on antigen-antibody complexes. Thanks to the development of highly sensitive microcalorimeters, the thermodynamic parameters of antigen-antibody interactions can now be measured with precision and using only nanomole quantities of protein. The method of choice is isothermal titration calorimetry, in which a solution of the antibody (or antigen) is titrated with small aliquots of the antigen (or antibody) and the heat change accompanying the formation of the antigen-antibody complex is measured with a sensitivity as high as 0.1 μcal s-1. The free energy of binding (DeltaG), the binding enthalpy (DeltaH), and the binding entropy (DeltaS) are usually obtained from a single experiment, and no spectroscopic or radioactive label must be introduced into the antigen or antibody. The often large and negative change in heat capacity (DeltaCp) accompanying the formation of an antigen-antibody complex is obtained from DeltaH measured at different temperatures. The basic theory and the principle of the measurements are reviewed and illustrated by examples. The thermodynamic parameters relate to the dynamic physical forces that govern the association of the freely moving antigen and antibody into a well-structured and unique complex. This information complements the static picture of the antigen-antibody complex that results from X-ray diffraction analysis. Attempts to correlate dynamic and static aspects are discussed briefly.

Spectral, thermal, and molecular modeling studies on the encapsulation of selected sulfonamide drugs in β-cyclodextrin nano-cavity

NASA Astrophysics Data System (ADS)

Bani-Yaseen, Abdulilah Dawoud; Mo'ala, Abeer

2014-10-01

In the present work the inclusion complexation of three sulfonamide (SA) drugs, namely sulfisoxazole (SSX), sulfamethizole (SMZ), and Sulfamethazine (STM) with β-cyclodextrin (β-CD) has been investigated using UV-Vis spectroscopy, DSC, 1H NMR spectroscopy, and molecular modeling methods. The binding constant (Kb) of SA:β-CD inclusion complexation was determined via applying the modified form of Benesi-Hildebrand equation employing the changes in absorbance at λmax. Obtained results revealed that SA drugs form 1:1 inclusion complex with β-CD with Kb of 650, 1532, 714 M-1 at 25 °C for SSX, SMZ, and STM, respectively. The UV-Vis absorption spectra displayed solvatochromic behavior of bathochromic shift with decreasing solvent polarity that in turn is good agreement with their behavior in the presence of β-CD in terms of environment polarity dependency. The inclusion complex formation between β-CD and tested SA drugs in liquid and solid states was confirmed by 1H NMR and DSC, respectively. Using semi-empirical quantum chemistry methods at PM3 theoretical level, inclusion complexes' structures as well as energetic and thermodynamic parameters of encapsulation were elucidated. Obtained results revealed that the encapsulation is favorably energetic and enthalpic in nature with the inclusion of the aniline moiety through the wide rim side of β-CD nano-cavity. Further, molecular modeling revealed that β-CD encapsulation of SA drugs reduced their (EHOMO - ELUMO) gap.

Off-pathway assembly of fimbria subunits is prevented by chaperone CfaA of CFA/I fimbriae from enterotoxigenic E. coli.

PubMed

Bao, Rui; Liu, Yang; Savarino, Stephen J; Xia, Di

2016-12-01

The assembly of the class 5 colonization factor antigen I (CFA/I) fimbriae of enterotoxigenic E. coli was proposed to proceed via the alternate chaperone-usher pathway. Here, we show that in the absence of the chaperone CfaA, CfaB, the major pilin subunit of CFA/I fimbriae, is able to spontaneously refold and polymerize into cyclic trimers. CfaA kinetically traps CfaB to form a metastable complex that can be stabilized by mutations. Crystal structure of the stabilized complex reveals distinctive interactions provided by CfaA to trap CfaB in an assembly competent state through donor-strand complementation (DSC) and cleft-mediated anchorage. Mutagenesis indicated that DSC controls the stability of the chaperone-subunit complex and the cleft-mediated anchorage of the subunit C-terminus additionally assist in subunit refolding. Surprisingly, over-stabilization of the chaperone-subunit complex led to delayed fimbria assembly, whereas destabilizing the complex resulted in no fimbriation. Thus, CfaA acts predominantly as a kinetic trap by stabilizing subunit to avoid its off-pathway self-polymerization that results in energetically favorable trimers and could serve as a driving force for CFA/I pilus assembly, representing an energetic landscape unique to class 5 fimbria assembly. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Molecular Microbiology published by John Wiley & Sons Ltd.

Challenges to providing pre-travel care for travellers visiting friends and relatives: an audit of a specialist travel medicine clinic.

PubMed

Rowe, Kate; Chaves, Nadia; Leder, Karin

2017-09-01

Travellers visiting friends and relatives (VFRs) often have complex pre-travel needs. We identified the characteristics, destinations, vaccinations and pre-travel advice provided to VFRs and compared these with non-VFR travellers. The significant differences we found suggest that future research should focus on improving the uptake of recommended interventions in VFR travellers. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

'We are always in some form of contact': friendships among homeless drug and alcohol users living in hostels.

PubMed

Neale, Joanne; Brown, Caral

2016-09-01

Homeless drug and alcohol users are one of the most marginalised groups in society. They frequently have complex needs and limited social support. In this paper, we explore the role of friendship in the lives of homeless drug and alcohol users living in hostels, using the concepts of 'social capital' and 'recovery capital' to frame the analyses. The study was undertaken in three hostels, each in a different English city, during 2013-2014. Audio recorded semi-structured interviews were conducted with 30 residents (9 females; 21 males) who self-reported drink and/or drug problems; follow-up interviews were completed 4-6 weeks later with 22 participants (6 females; 16 males). Data were transcribed verbatim, coded using the software package MAXQDA, and analysed using Framework. Only 21 participants reported current friends at interview 1, and friendship networks were small and changeable. Despite this, participants desired friendships that were culturally normative. Eight categories of friend emerged from the data: family-like friends; using friends; homeless friends; childhood friends; online-only friends; drug treatment friends; work friends; and mutual interest friends. Routine and regular contact was highly valued, with family-like friends appearing to offer the most constant practical and emotional support. The use of information and communication technologies (ICTs) was central to many participants' friendships, keeping them connected to social support and recovery capital outside homelessness and substance-using worlds. We conclude that those working with homeless drug and alcohol users - and potentially other marginalised populations - could beneficially encourage their clients to identify and build upon their most positive and reliable relationships. Additionally, they might explore ways of promoting the use of ICTs to combat loneliness and isolation. Texting, emailing, online mutual aid meetings, chatrooms, Internet penpals, skyping and other social media all offer potentially valuable opportunities for building friendships that can bolster otherwise limited social and recovery capital. © 2015 The Authors. Health and Social Care in the Community Published by John Wiley & Sons Ltd.

Molecular determinants of the interactions between proteins and ssDNA.

PubMed

Mishra, Garima; Levy, Yaakov

2015-04-21

ssDNA binding proteins (SSBs) protect ssDNA from chemical and enzymatic assault that can derail DNA processing machinery. Complexes between SSBs and ssDNA are often highly stable, but predicting their structures is challenging, mostly because of the inherent flexibility of ssDNA and the geometric and energetic complexity of the interfaces that it forms. Here, we report a newly developed coarse-grained model to predict the structure of SSB-ssDNA complexes. The model is successfully applied to predict the binding modes of six SSBs with ssDNA strands of lengths of 6-65 nt. In addition to charge-charge interactions (which are often central to governing protein interactions with nucleic acids by means of electrostatic complementarity), an essential energetic term to predict SSB-ssDNA complexes is the interactions between aromatic residues and DNA bases. For some systems, flexibility is required from not only the ssDNA but also, the SSB to allow it to undergo conformational changes and the penetration of the ssDNA into its binding pocket. The association mechanisms can be quite varied, and in several cases, they involve the ssDNA sliding along the protein surface. The binding mechanism suggests that coarse-grained models are appropriate to study the motion of SSBs along ssDNA, which is expected to be central to the function carried out by the SSBs.

Bonding and Mobility of Alkali Metals in Helicenes.

PubMed

Barroso, Jorge; Murillo, Fernando; Martínez-Guajardo, Gerardo; Ortíz-Chi, Filiberto; Pan, Sudip; Fernández-Herrera, María A; Merino, Gabriel

2018-06-04

In this work, we analyze the interaction of alkali metal cations with [6]- and [14]helicene and the cation mobility of therein. We found that the distortion of the carbon skeleton is the cause that some of the structures that are local minima for the smallest cations are not energetically stable for K+, Rb+, and Cs+. Also, the most favorable complexes are those where the cation is interacting with two rings forming a metallocene-like structure, except for the largest cation Cs+, where the distortion provoked by the size of the cation desestabilizes the complex. As far as mobility is concerned, the smallest cations, particularly Na+, are the ones that can move most efficiently. In [6]helicene, the mobility is limited by the capture of the cation forming the metallocene-like structure. In larger helicenes, the energy barriers for the cation to move are similar both inside and outside the helix. However, complexes with the cation between two layers are more energetically favored so that the movement will be preferred in that region. The bonding analysis reveals that interactions with no less than 50% of orbitalic contribution are taking place for the series of E+-[6]helicene. Particularly, the complexes of Li+ stand out showing a remarkably orbitalic character bonding (72.5 - 81.6%). © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Unraveling the synthesis of homoleptic [Ag(N,N-diaryl-NHC)2]Y (Y = BF4, PF6) complexes by ball-milling.

PubMed

Beillard, Audrey; Bantreil, Xavier; Métro, Thomas-Xavier; Martinez, Jean; Lamaty, Frédéric

2016-11-28

A user-friendly and general mechanochemical method was developed to access rarely described NHC (N-heterocyclic carbene) silver(i) complexes featuring N,N-diarylimidazol(idin)ene ligands and non-coordinating tetrafluoroborate or hexafluorophosphate counter anions. Comparison with syntheses in solution clearly demonstrated the superiority of the ball-milling conditions.

In situ TEM of radiation effects in complex ceramics.

PubMed

Lian, Jie; Wang, L M; Sun, Kai; Ewing, Rodney C

2009-03-01

In situ transmission electron microscopy (TEM) has been extensively applied to study radiation effects in a wide variety of materials, such as metals, ceramics and semiconductors and is an indispensable tool in obtaining a fundamental understanding of energetic beam-matter interactions, damage events, and materials' behavior under intense radiation environments. In this article, in situ TEM observations of radiation effects in complex ceramics (e.g., oxides, silicates, and phosphates) subjected to energetic ion and electron irradiations have been summarized with a focus on irradiation-induced microstructural evolution, changes in microchemistry, and the formation of nanostructures. New results for in situ TEM observation of radiation effects in pyrochlore, A(2)B(2)O(7), and zircon, ZrSiO(4), subjected to multiple beam irradiations are presented, and the effects of simultaneous irradiations of alpha-decay and beta-decay on the microstructural evolution of potential nuclear waste forms are discussed. Furthermore, in situ TEM results of radiation effects in a sodium borosilicate glass subjected to electron-beam exposure are introduced to highlight the important applications of advanced analytical TEM techniques, including Z-contrast imaging, energy filtered TEM (EFTEM), and electron energy loss spectroscopy (EELS), in studying radiation effects in materials microstructural evolution and microchemical changes. By combining ex situ TEM and advanced analytical TEM techniques with in situ TEM observations under energetic beam irradiations, one can obtain invaluable information on the phase stability and response behaviors of materials under a wide range of irradiation conditions. (c) 2009 Wiley-Liss, Inc.

Sculpting Nanoscale Functional Channels in Complex Oxides Using Energetic Ions and Electrons

DOE PAGES

Sachan, Ritesh; Zarkadoula, Eva; Ou, Xin; ...

2018-04-26

The formation of metastable phases has attracted significant attention because of their unique properties and potential functionalities. In the present study, we demonstrate the phase conversion of energetic-ion-induced amorphous nanochannels/tracks into a metastable defect fluorite in A 2B 2O 7 structured complex oxides by electron irradiation. Through in situ electron irradiation experiments in a scanning transmission electron microscope, we observe electron-induced epitaxial crystallization of the amorphous nanochannels in Yb 2Ti 2O 7 into the defect fluorite. This energetic-electron-induced phase transformation is attributed to the coupled effect of ionization-induced electronic excitations and local heating, along with subthreshold elastic energy transfers. Wemore » also show the role of ionic radii of A-site cations (A = Yb, Gd, and Sm) and B-site cations (Ti and Zr) in facilitating the electron-beam-induced crystallization of the amorphous phase to the defect-fluorite structure. The formation of the defect-fluorite structure is eased by the decrease in the difference between ionic radii of A- and B-site cations in the lattice. Molecular dynamics simulations of thermal annealing of the amorphous phase nanochannels in A 2B 2O 7 draw parallels to the electron-irradiation-induced crystallization and confirm the role of ionic radii in lowering the barrier for crystallization. Furthermore, these results suggest that employing guided electron irradiation with atomic precision is a useful technique for selected area phase formation in nanoscale printed devices.« less

Sculpting Nanoscale Functional Channels in Complex Oxides Using Energetic Ions and Electrons

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

Sachan, Ritesh; Zarkadoula, Eva; Ou, Xin

The formation of metastable phases has attracted significant attention because of their unique properties and potential functionalities. In the present study, we demonstrate the phase conversion of energetic-ion-induced amorphous nanochannels/tracks into a metastable defect fluorite in A 2B 2O 7 structured complex oxides by electron irradiation. Through in situ electron irradiation experiments in a scanning transmission electron microscope, we observe electron-induced epitaxial crystallization of the amorphous nanochannels in Yb 2Ti 2O 7 into the defect fluorite. This energetic-electron-induced phase transformation is attributed to the coupled effect of ionization-induced electronic excitations and local heating, along with subthreshold elastic energy transfers. Wemore » also show the role of ionic radii of A-site cations (A = Yb, Gd, and Sm) and B-site cations (Ti and Zr) in facilitating the electron-beam-induced crystallization of the amorphous phase to the defect-fluorite structure. The formation of the defect-fluorite structure is eased by the decrease in the difference between ionic radii of A- and B-site cations in the lattice. Molecular dynamics simulations of thermal annealing of the amorphous phase nanochannels in A 2B 2O 7 draw parallels to the electron-irradiation-induced crystallization and confirm the role of ionic radii in lowering the barrier for crystallization. Furthermore, these results suggest that employing guided electron irradiation with atomic precision is a useful technique for selected area phase formation in nanoscale printed devices.« less

Thermodynamic dissection of the binding energetics of proline-rich peptides to the Abl-SH3 domain: implications for rational ligand design.

PubMed

Palencia, Andrés; Cobos, Eva S; Mateo, Pedro L; Martínez, Jose C; Luque, Irene

2004-02-13

The inhibition of the interactions between SH3 domains and their targets is emerging as a promising therapeutic strategy. To date, rational design of potent ligands for these domains has been hindered by the lack of understanding of the origins of the binding energy. We present here a complete thermodynamic analysis of the binding energetics of the p41 proline-rich decapeptide (APSYSPPPPP) to the SH3 domain of the c-Abl oncogene. Isothermal titration calorimetry experiments have revealed a thermodynamic signature for this interaction (very favourable enthalpic contributions opposed by an unfavourable binding entropy) inconsistent with the highly hydrophobic nature of the p41 ligand and the Abl-SH3 binding site. Our structural and thermodynamic analyses have led us to the conclusion, having once ruled out any possible ionization events or conformational changes coupled to the association, that the establishment of a complex hydrogen-bond network mediated by water molecules buried at the binding interface is responsible for the observed thermodynamic behaviour. The origin of the binding energetics for proline-rich ligands to the Abl-SH3 domain is further investigated by a comparative calorimetric analysis of a set of p41-related ligands. The striking effects upon the enthalpic and entropic contributions provoked by conservative substitutions at solvent-exposed positions in the ligand confirm the complexity of the interaction. The implications of these results for rational ligand design are discussed.

Rainbow trout consume less oxygen in turbulence: the energetics of swimming behaviors at different speeds

PubMed Central

Taguchi, Masashige; Liao, James C.

2011-01-01

SUMMARY Measuring the rate of consumption of oxygen () during swimming reveals the energetics of fish locomotion. We show that rainbow trout have substantially different oxygen requirements for station holding depending on which hydrodynamic microhabitats they choose to occupy around a cylinder. We used intermittent flow respirometry to show that an energetics hierarchy, whereby certain behaviors are more energetically costly than others, exists both across behaviors at a fixed flow velocity and across speeds for a single behavior. At 3.5 L s–1 (L is total body length) entraining has the lowest , followed by Kármán gaiting, bow waking and then free stream swimming. As flow speed increases the costs associated with a particular behavior around the cylinder changes in unexpected ways compared with free stream swimming. At times, actually decreases as flow velocity increases. Entraining demands the least oxygen at 1.8 L s–1 and 3.5 L s–1, whereas bow waking requires the least oxygen at 5.0 L s–1. Consequently, a behavior at one speed may have a similar cost to another behavior at another speed. We directly confirm that fish Kármán gaiting in a vortex street gain an energetic advantage from vortices beyond the benefit of swimming in a velocity deficit. We propose that the ability to exploit velocity gradients as well as stabilization costs shape the complex patterns of oxygen consumption for behaviors around cylinders. Measuring for station holding in turbulent flows advances our attempts to develop ecologically relevant approaches to evaluating fish swimming performance. PMID:21490251

What have we learned about the energetic particle dynamics in the inner belt and slot region from Van Allen Probes and CSSWE missions?

NASA Astrophysics Data System (ADS)

Li, Xinlin; Selesnick, Richard; Zhao, Hong; Baker, Dan; Jaynes, Allison; Kanekal, Shrikanth; Bern Blake, J.

2017-04-01

Comprehensive measurements of energetic protons (10s of MeV) in the inner belt (L<2) and slot region (21.6 MeV) measurements cannot be distinguished from the background. Analysis on sub-MeV electrons data in the inner belt and slot region from the Magnetic Electron Ion Spectrometer (MagEIS) on board Van Allen Probes revealed rather complex pitch angle distribution of these energetic electrons, with the 90 deg-minimum (butterfly) pitch angle distribution dominating near the magnetic equator, which has inspired a great deal of theoretical interest in an attempt to explain such a peculiar pitch angle distribution. These are part of a summary of the most recent measurements and understanding of the dynamics of energetic particles in the inner zone and slot region to be exhibited and discussed in this presentation.

Exploring PHD fingers and H3K4me0 interactions with molecular dynamics simulations and binding free energy calculations: AIRE-PHD1, a comparative study.

PubMed

Spiliotopoulos, Dimitrios; Spitaleri, Andrea; Musco, Giovanna

2012-01-01

PHD fingers represent one of the largest families of epigenetic readers capable of decoding post-translationally modified or unmodified histone H3 tails. Because of their direct involvement in human pathologies they are increasingly considered as a potential therapeutic target. Several PHD/histone-peptide structures have been determined, however relatively little information is available on their dynamics. Studies aiming to characterize the dynamic and energetic determinants driving histone peptide recognition by epigenetic readers would strongly benefit from computational studies. Herein we focus on the dynamic and energetic characterization of the PHD finger subclass specialized in the recognition of histone H3 peptides unmodified in position K4 (H3K4me0). As a case study we focused on the first PHD finger of autoimmune regulator protein (AIRE-PHD1) in complex with H3K4me0. PCA analysis of the covariance matrix of free AIRE-PHD1 highlights the presence of a "flapping" movement, which is blocked in an open conformation upon binding to H3K4me0. Moreover, binding free energy calculations obtained through Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) methodology are in good qualitative agreement with experiments and allow dissection of the energetic terms associated with native and alanine mutants of AIRE-PHD1/H3K4me0 complexes. MM/PBSA calculations have also been applied to the energetic analysis of other PHD fingers recognizing H3K4me0. In this case we observe excellent correlation between computed and experimental binding free energies. Overall calculations show that H3K4me0 recognition by PHD fingers relies on compensation of the electrostatic and polar solvation energy terms and is stabilized by non-polar interactions.

SPECT3D - A multi-dimensional collisional-radiative code for generating diagnostic signatures based on hydrodynamics and PIC simulation output

NASA Astrophysics Data System (ADS)

MacFarlane, J. J.; Golovkin, I. E.; Wang, P.; Woodruff, P. R.; Pereyra, N. A.

2007-05-01

SPECT3D is a multi-dimensional collisional-radiative code used to post-process the output from radiation-hydrodynamics (RH) and particle-in-cell (PIC) codes to generate diagnostic signatures (e.g. images, spectra) that can be compared directly with experimental measurements. This ability to post-process simulation code output plays a pivotal role in assessing the reliability of RH and PIC simulation codes and their physics models. SPECT3D has the capability to operate on plasmas in 1D, 2D, and 3D geometries. It computes a variety of diagnostic signatures that can be compared with experimental measurements, including: time-resolved and time-integrated spectra, space-resolved spectra and streaked spectra; filtered and monochromatic images; and X-ray diode signals. Simulated images and spectra can include the effects of backlighters, as well as the effects of instrumental broadening and time-gating. SPECT3D also includes a drilldown capability that shows where frequency-dependent radiation is emitted and absorbed as it propagates through the plasma towards the detector, thereby providing insights on where the radiation seen by a detector originates within the plasma. SPECT3D has the capability to model a variety of complex atomic and radiative processes that affect the radiation seen by imaging and spectral detectors in high energy density physics (HEDP) experiments. LTE (local thermodynamic equilibrium) or non-LTE atomic level populations can be computed for plasmas. Photoabsorption rates can be computed using either escape probability models or, for selected 1D and 2D geometries, multi-angle radiative transfer models. The effects of non-thermal (i.e. non-Maxwellian) electron distributions can also be included. To study the influence of energetic particles on spectra and images recorded in intense short-pulse laser experiments, the effects of both relativistic electrons and energetic proton beams can be simulated. SPECT3D is a user-friendly software package that runs on Windows, Linux, and Mac platforms. A parallel version of SPECT3D is supported for Linux clusters for large-scale calculations. We will discuss the major features of SPECT3D, and present example results from simulations and comparisons with experimental data.

Plasma and Electro-energetic Physics

DTIC Science & Technology

2012-03-07

Dynamical Equations (with complex surfaces ): Relativistic Lorentz Force Law for relativistic momentum p and velocity u: tDcJcH tBcE   /)/1()/4...0.1-1 s • 3D, high-fidelity, parallel modeling of high energy density fields and particles in complex geometry with some surface effects...cathodes (500 µm separation) Tang, AFRL/RD 12 DISTRIBUTION A: Approved for public release; distribution is unlimited. ICEPIC simulations Equipotential

Energetic Ionic Liquids Based on Anionic Rare Earth Nitrate Complexes (Preprint)

DTIC Science & Technology

2008-07-10

a glass transition temperature (Tg) at -46 oC. However, it is only stable in dry air, and thus must be protected from water. At 75 oC, clear weight...involved highly toxic and corrosive chemicals, N2O4 and NOCl. Ligands which coordinate via oxygen atoms to a rare earth metal ion give rise to stable...complexes. Thus higher air and thermal stabilities may be obtained by introducing rare earth metal nitrates as main components of ionic liquids. We

Peer influence and context: the interdependence of friendship groups, schoolmates and network density in predicting substance use.

PubMed

McGloin, Jean Marie; Sullivan, Christopher J; Thomas, Kyle J

2014-09-01

This article focuses on the degree to which friends' influence on substance use is conditioned by the consistency between their behavior and that of schoolmates (individuals enrolled in the same school, but not identified as friends), contributing to the literature on the complexity of interactive social influences during adolescence. Specifically, it hypothesizes that friends' influence will diminish as their norms become less similar to that of schoolmates. The authors also propose that this conditioning relationship is related to the density of the friendship group. This study uses data from the National Longitudinal Survey of Adolescent Health (AddHealth) (n ~ 8,000, 55% female) to examine the interactive relationship between friend and schoolmate influences on adolescent substance use (smoking and drinking). The sample contains students ranging from age 11 to 22 and is 60% White. The findings demonstrate that, as the substance use of the friendship group becomes more dissimilar from schoolmates' substance use, the friendship group's influence on adolescent substance use diminishes. Further, the results demonstrate that this conditioning relationship does not emerge when the friendship group is highly dense.

Characterising Tidal Flow Within AN Energetic Tidal Environment

NASA Astrophysics Data System (ADS)

Neill, S. P.; Goward Brown, A.; Lewis, M. J.

2016-02-01

The Pentland Firth is a highly energetic and complex tidal strait separating the north of Scotland with the Orkney Islands and is a key location for tidal energy exploitation. Topographic features including islands and headlands, combined with bathymetric complexities within the Pentland Firth create turbulent hydrodynamic flows which are difficult to observe. Site selection in tidal energy environments historically focuses on tidal current magnitude. Without consideration for the more complex hydrodynamics of tidal energy environments tidal energy developers may miss the opportunity to tune their devices or create environment specific tidal energy converters in order to harness the greatest potential from site. Fully characterising these tidal energy environments ensures economic energy extraction. Understanding the interaction of energy extraction with the environment will reduce uncertainty in site selection and allow mitigation of any potential environmental concerns. We apply the 3D ROMS model to the Pentland Firth with the aim of resolving uncertainties within tidal energy resource assessment. Flow magnitudes and directions are examined with a focus on tidal phasing and asymmetry and application to sediment dynamics. Using the ROMS model, it is possible to determine the extent to which the tidal resource varies temporally and spatially with tidal energy extraction. Accurately modelling the tidal dynamics within this environment ensures that potential consequences of tidal energy extraction on the surrounding environment are better understood.

KENNEDY SPACE CENTER, FLA. - Center Director Jim Kennedy speaks to attendees at a memorial service honoring the crew of Columbia. He stands in front of the Space Memorial Mirror at the KSC Visitor Complex. Feb. 1 is the one-year anniversary of the loss of the crew and orbiter Columbia in a tragic accident as the ship returned to Earth following mission STS-107. Attended by many friends, co-workers and families, the memorial service was also open to the public.

NASA Image and Video Library

2004-02-01

KENNEDY SPACE CENTER, FLA. - Center Director Jim Kennedy speaks to attendees at a memorial service honoring the crew of Columbia. He stands in front of the Space Memorial Mirror at the KSC Visitor Complex. Feb. 1 is the one-year anniversary of the loss of the crew and orbiter Columbia in a tragic accident as the ship returned to Earth following mission STS-107. Attended by many friends, co-workers and families, the memorial service was also open to the public.

Rapid fabrication of hierarchically structured supramolecular nanocomposite thin films in one minute

DOEpatents

Xu, Ting; Kao, Joseph

2016-11-08

Functional nanocomposites containing nanoparticles of different chemical compositions may exhibit new properties to meet demands for advanced technology. It is imperative to simultaneously achieve hierarchical structural control and to develop rapid, scalable fabrication to minimize degradation of nanoparticle properties and for compatibility with nanomanufacturing. The assembly kinetics of supramolecular nanocomposite in thin films is governed by the energetic cost arising from defects, the chain mobility, and the activation energy for inter-domain diffusion. By optimizing only one parameter, the solvent fraction in the film, the assembly kinetics can be precisely tailored to produce hierarchically structured thin films of supramolecular nanocomposites in approximately one minute. Moreover, the strong wavelength dependent optical anisotropy in the nanocomposite highlights their potential applications for light manipulation and information transmission. The present invention opens a new avenue in designing manufacture-friendly continuous processing for the fabrication of functional nanocomposite thin films.

Strain-induced bi-thermoelectricity in tapered carbon nanotubes

NASA Astrophysics Data System (ADS)

Algharagholy, L. A. A.; Pope, T.; Lambert, C. J.

2018-03-01

We show that carbon-based nanostructured materials are a novel testbed for controlling thermoelectricity and have the potential to underpin the development of new cost-effective environmentally-friendly thermoelectric materials. In single-molecule junctions, it is known that transport resonances associated with the discrete molecular levels play a key role in the thermoelectric performance, but such resonances have not been exploited in carbon nanotubes (CNTs). Here we study junctions formed from tapered CNTs and demonstrate that such structures possess transport resonances near the Fermi level, whose energetic location can be varied by applying strain, resulting in an ability to tune the sign of their Seebeck coefficient. These results reveal that tapered CNTs form a new class of bi-thermoelectric materials, exhibiting both positive and negative thermopower. This ability to change the sign of the Seebeck coefficient allows the thermovoltage in carbon-based thermoelectric devices to be boosted by placing CNTs with alternating-sign Seebeck coefficients in tandem.

Energetics and Dynamics Across the Bcl-2-Regulated Apoptotic Pathway Reveal Distinct Evolutionary Determinants of Specificity and Affinity.

PubMed

Ivanov, Stefan M; Huber, Roland G; Warwicker, Jim; Bond, Peter J

2016-11-01

Critical regulatory pathways are replete with instances of intra- and interfamily protein-protein interactions due to the pervasiveness of gene duplication throughout evolution. Discerning the specificity determinants within these systems has proven a challenging task. Here, we present an energetic analysis of the specificity determinants within the Bcl-2 family of proteins (key regulators of the intrinsic apoptotic pathway) via a total of ∼20 μs of simulation of 60 distinct protein-protein complexes. We demonstrate where affinity and specificity of protein-protein interactions arise across the family, and corroborate our conclusions with extensive experimental evidence. We identify energy and specificity hotspots that may offer valuable guidance in the design of targeted therapeutics for manipulating the protein-protein interactions within the apoptosis-regulating pathway. Moreover, we propose a conceptual framework that allows us to quantify the relationship between sequence, structure, and binding energetics. This approach may represent a general methodology for investigating other paralogous protein-protein interaction sites. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Radiation Belt Storm Probes (RBSP) Energetic Particle, Composition, and Thermal plasma (ECT) Suite: Upcoming Opportunties for Testing Radiation Belt Acceleration Mechanisms

NASA Astrophysics Data System (ADS)

Spence, Harlan; Reeves, Geoffrey

2012-07-01

The Radiation Belt Storm Probes (RBSP) mission will launch in late summer 2012 and begin its exploration of acceleration and dynamics of energetic particles in the inner magnetosphere. In this presentation, we discuss opportunities afforded by the RBSP Energetic Particle, Composition, and Thermal plasma (ECT) instrument suite to advance our understanding of acceleration processes in the radiation belts. The RBSP-ECT instrument suite comprehensively measures the electron and major ion populations of the inner magnetosphere, from the lowest thermal plasmas of the plasmasphere, to the hot plasma of the ring current, to the relativistic populations of the radiation belts. Collectively, the ECT measurements will reveal the complex cross-energy coupling of these colocated particle populations, which along with concurrent RBSP wave measurements, will permit various wave-particle acceleration mechanisms to be tested. We review the measurement capabilities of the RBSP-ECT instrument suite, and demonstrate several examples of how these measurements will be used to explore candidate acceleration mechanisms and dynamics of radiation belt particles.

CLUH couples mitochondrial distribution to the energetic and metabolic status.

PubMed

Wakim, Jamal; Goudenege, David; Perrot, Rodolphe; Gueguen, Naig; Desquiret-Dumas, Valerie; Chao de la Barca, Juan Manuel; Dalla Rosa, Ilaria; Manero, Florence; Le Mao, Morgane; Chupin, Stephanie; Chevrollier, Arnaud; Procaccio, Vincent; Bonneau, Dominique; Logan, David C; Reynier, Pascal; Lenaers, Guy; Khiati, Salim

2017-06-01

Mitochondrial dynamics and distribution are critical for supplying ATP in response to energy demand. CLUH is a protein involved in mitochondrial distribution whose dysfunction leads to mitochondrial clustering, the metabolic consequences of which remain unknown. To gain insight into the role of CLUH on mitochondrial energy production and cellular metabolism, we have generated CLUH-knockout cells using CRISPR/Cas9. Mitochondrial clustering was associated with a smaller cell size and with decreased abundance of respiratory complexes, resulting in oxidative phosphorylation (OXPHOS) defects. This energetic impairment was found to be due to the alteration of mitochondrial translation and to a metabolic shift towards glucose dependency. Metabolomic profiling by mass spectroscopy revealed an increase in the concentration of some amino acids, indicating a dysfunctional Krebs cycle, and increased palmitoylcarnitine concentration, indicating an alteration of fatty acid oxidation, and a dramatic decrease in the concentrations of phosphatidylcholine and sphingomyeline, consistent with the decreased cell size. Taken together, our study establishes a clear function for CLUH in coupling mitochondrial distribution to the control of cell energetic and metabolic status. © 2017. Published by The Company of Biologists Ltd.

The isolated voltage sensing domain of the Shaker potassium channel forms a voltage-gated cation channel

PubMed Central

Zhao, Juan; Blunck, Rikard

2016-01-01

Domains in macromolecular complexes are often considered structurally and functionally conserved while energetically coupled to each other. In the modular voltage-gated ion channels the central ion-conducting pore is surrounded by four voltage sensing domains (VSDs). Here, the energetic coupling is mediated by interactions between the S4-S5 linker, covalently linking the domains, and the proximal C-terminus. In order to characterize the intrinsic gating of the voltage sensing domain in the absence of the pore domain, the Shaker Kv channel was truncated after the fourth transmembrane helix S4 (Shaker-iVSD). Shaker-iVSD showed significantly altered gating kinetics and formed a cation-selective ion channel with a strong preference for protons. Ion conduction in Shaker-iVSD developed despite identical primary sequence, indicating an allosteric influence of the pore domain. Shaker-iVSD also displays pronounced 'relaxation'. Closing of the pore correlates with entry into relaxation suggesting that the two processes are energetically related. DOI: http://dx.doi.org/10.7554/eLife.18130.001 PMID:27710769

Interplay of confinement and surface energetics in the interaction of water with a metal–organic framework

DOE PAGES

Wu, Di; Guo, Xiaofeng; Sun, Hui; ...

2016-03-24

Here, the enthalpy of water adsorption (Δh) on the metal–organic framework (MOF) HKUST-1 has been determined directly by calorimetry. The most exothermic value of Δh [–119.4 ± 0.5 kJ/(mol of water)] occurs at zero coverage and perhaps represents water confinement in the smallest (4-Å) cages. An intermediate Δh value of –50.2 ± 1.8 kJ/(mol of water) at higher loading probably corresponds to the binding of water on the available Cu nodes and subsequent filling of the largest (11-Å) pores. The weakest interactions take place in the medium (10-Å) cages, showing weak inclusion of water clusters in a limited hydrophobic environment.more » By combining ethanol adsorption calorimetry, mathematical analysis of the slope of the water adsorption isotherm, and the differential enthalpy of water adsorption curve, we are able not only to develop an approach to separate energetically multistage guest–host interactions in complex MOF architectures but also to distinguish a sequence of interactions with very similar energetic effects.« less

Using molecular recognition of beta-cyclodextrin to determine molecular weights of low-molecular-weight explosives by MALDI-TOF mass spectrometry.

PubMed

Zhang, Min; Shi, Zhen; Bai, Yinjuan; Gao, Yong; Hu, Rongzu; Zhao, Fenqi

2006-02-01

This study presents a novel method for determining the molecular weights of low molecular weight (MW) energetic compounds through their complexes of beta-cyclodextrin (beta-CD) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) in a mass range of 500 to 1700 Da, avoiding matrix interference. The MWs of one composite explosive composed of 2,6-DNT, TNT, and RDX, one propellant with unknown components, and 14 single-compound explosives (RDX, HMX, 3,4-DNT, 2,6-DNT, 2,5-DNT, 2,4,6-TNT, TNAZ, DNI, BTTN, NG, TO, NTO, NP, and 662) were measured. The molecular recognition and inclusion behavior of beta-CD to energetic materials (EMs) were investigated. The results show that (1) the established method is sensitive, simple, accurate, and suitable for determining the MWs of low-MW single-compound explosives and energetic components in composite explosives and propellants; and (2) beta-CD has good inclusion and modular recognition abilities to the above EMs.

Dispersion Corrected Structural Properties and Quasiparticle Band Gaps of Several Organic Energetic Solids.

PubMed

Appalakondaiah, S; Vaitheeswaran, G; Lebègue, S

2015-06-18

We have performed ab initio calculations for a series of energetic solids to explore their structural and electronic properties. To evaluate the ground state volume of these molecular solids, different dispersion correction methods were accounted in DFT, namely the Tkatchenko-Scheffler method (with and without self-consistent screening), Grimme's methods (D2, D3(BJ)), and the vdW-DF method. Our results reveal that dispersion correction methods are essential in understanding these complex structures with van der Waals interactions and hydrogen bonding. The calculated ground state volumes and bulk moduli show that the performance of each method is not unique, and therefore a careful examination is mandatory for interpreting theoretical predictions. This work also emphasizes the importance of quasiparticle calculations in predicting the band gap, which is obtained here with the GW approximation. We find that the obtained band gaps are ranging from 4 to 7 eV for the different compounds, indicating their insulating nature. In addition, we show the essential role of quasiparticle band structure calculations to correlate the gap with the energetic properties.

Axial and equatorial hydrogen-bond conformers between (CH2)3S and H(D)F: Fourier transform infrared spectroscopy and ab initio calculations.

PubMed

Madebène, B; Asselin, P; Soulard, P; Alikhani, M E

2011-08-21

The coexistence of axial and equatorial hydrogen-bonded conformers of 1 : 1 (CH(2))(3)S-HF (and -DF) has been observed in the same adiabatic expansion of a supersonic jet seeded with argon and in a static absorption cell at room temperature. High level calculations computed the axial conformer to be the most stable one with a small energy difference with respect to the equatorial one, in full agreement with previous microwave experiments. On the grounds of band contour simulations of FTIR spectra and ab initio energetic and anharmonic vibrational calculations, two pairs of ν(s) HF donor stretching bands, observed in a series of jet-FTIR spectra at 3457.9 and 3480.5 cm(-1) have been respectively assigned to the axial and equatorial forms of the 1 : 1 complex. In the jet-FTIR spectra series with HF, the assignment of an additional broad band (about 200 cm(-1) higher in frequency with respect to ν(s)) to a 1 : 2 complex has been supported by theoretical investigations. Experimental detection of both axial and equatorial forms of a cyclic trimer has been confirmed by calculated energetic and vibrational properties. The nature of hydrogen bonding has been examined within topological frameworks. The energetic partitioning within the 1 : 1 dimers has been elucidated with SAPT techniques. Interestingly, the interconversion pathway between two 1 : 1 structures has been explored and it was seen that the formation of the 1 : 1 complex affects the interconversion barrier on the ring puckering motion. The band contour analysis of gas phase FTIR experiments provided a consistent set of vibrational frequencies and anharmonic coupling constants, in good agreement with ab initio anharmonic vibrational calculations. Finally, from a series of cell-FTIR spectra recorded at different partial pressures of (CH(2))(3)S and HF monomers, the absorption signal of the 1 : 1 complex could be isolated which enabled to estimate the equilibrium constant K(p) = 0.023 at 298 K for the dimerization.

Microstructure and Mixing: Interactions of Energetic Flow and Eddies with Complex Topography in the Western Indian Ocean

DTIC Science & Technology

2015-09-17

the region of interest from SAEON archives Task 3 An offshore survey - to make some basic measurements in the area of interest and develop AUV ... AUV deployment procedures and skills using local resources. 4. Glider deployment in collaboration with WHOI YEAR 2 1. Further measurements based

Potential limitations of NRC in predicting energetic requirements of beef females within western U.S. grazing systems

USDA-ARS?s Scientific Manuscript database

Assessment of beef cow energy balance and efficiency in grazing-extensive rangelands has occurred on a nominal basis over short time intervals and has not accounted for the complexity of metabolic and digestive responses; behavioral adaptations to climatic, terrain, and vegetation variables; and doc...

Distinct peptide binding specificities of Src homology 3 (SH3) protein domains can be determined by modulation of local energetics across the binding interface.

PubMed

Gorelik, Maryna; Davidson, Alan R

2012-03-16

The yeast Nbp2p SH3 and Bem1p SH3b domains bind certain target peptides with similar high affinities, yet display vastly different affinities for other targets. To investigate this unusual behavior, we have solved the structure of the Nbp2p SH3-Ste20 peptide complex and compared it with the previously determined structure of the Bem1p SH3b bound to the same peptide. Although the Ste20 peptide interacts with both domains in a structurally similar manner, extensive in vitro studies with domain and peptide mutants revealed large variations in interaction strength across the binding interface of the two complexes. Whereas the Nbp2p SH3 made stronger contacts with the peptide core RXXPXXP motif, the Bem1p SH3b domain made stronger contacts with residues flanking the core motif. Remarkably, this modulation of local binding energetics can explain the distinct and highly nuanced binding specificities of these two domains.

The radiation environment on the surface of Mars - Summary of model calculations and comparison to RAD data.

PubMed

Matthiä, Daniel; Hassler, Donald M; de Wet, Wouter; Ehresmann, Bent; Firan, Ana; Flores-McLaughlin, John; Guo, Jingnan; Heilbronn, Lawrence H; Lee, Kerry; Ratliff, Hunter; Rios, Ryan R; Slaba, Tony C; Smith, Michael; Stoffle, Nicholas N; Townsend, Lawrence W; Berger, Thomas; Reitz, Günther; Wimmer-Schweingruber, Robert F; Zeitlin, Cary

2017-08-01

The radiation environment at the Martian surface is, apart from occasional solar energetic particle events, dominated by galactic cosmic radiation, secondary particles produced in their interaction with the Martian atmosphere and albedo particles from the Martian regolith. The highly energetic primary cosmic radiation consists mainly of fully ionized nuclei creating a complex radiation field at the Martian surface. This complex field, its formation and its potential health risk posed to astronauts on future manned missions to Mars can only be fully understood using a combination of measurements and model calculations. In this work the outcome of a workshop held in June 2016 in Boulder, CO, USA is presented: experimental results from the Radiation Assessment Detector of the Mars Science Laboratory are compared to model results from GEANT4, HETC-HEDS, HZETRN, MCNP6, and PHITS. Charged and neutral particle spectra and dose rates measured between 15 November 2015 and 15 January 2016 and model results calculated for this time period are investigated. Copyright © 2017 The Committee on Space Research (COSPAR). All rights reserved.

In vitro methanol production from methyl coenzyme M using the Methanosarcina barkeri MtaABC protein complex.

PubMed

Dong, Ming; Gonzalez, Tara D; Klems, Meghan M; Steinberg, Lisa M; Chen, Wilfred; Papoutsakis, Eleftherios T; Bahnson, Brian J

2017-09-01

Methanol:coenzyme M methyltransferase is an enzyme complex composed of three subunits, MtaA, MtaB, and MtaC, found in methanogenic archaea and is needed for their growth on methanol ultimately producing methane. MtaABC catalyzes the energetically favorable methyl transfer from methanol to coenzyme M to form methyl coenzyme M. Here we demonstrate that this important reaction for possible production of methanol from the anaerobic oxidation of methane can be reversed in vitro. To this effect, we have expressed and purified the Methanosarcina barkeri MtaABC enzyme, and developed an in vitro functional assay that demonstrates MtaABC can catalyze the energetically unfavorable (ΔG° = 27 kJ/mol) reverse reaction starting from methyl coenzyme M and generating methanol as a product. Demonstration of an in vitro ability of MtaABC to produce methanol may ultimately enable the anaerobic oxidation of methane to produce methanol and from methanol alternative fuel or fuel-precursor molecules. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1243-1249, 2017. © 2017 American Institute of Chemical Engineers.

Energetics of codon-anticodon recognition on the small ribosomal subunit.

PubMed

Almlöf, Martin; Andér, Martin; Aqvist, Johan

2007-01-09

Recent crystal structures of the small ribosomal subunit have made it possible to examine the detailed energetics of codon recognition on the ribosome by computational methods. The binding of cognate and near-cognate anticodon stem loops to the ribosome decoding center, with mRNA containing the Phe UUU and UUC codons, are analyzed here using explicit solvent molecular dynamics simulations together with the linear interaction energy (LIE) method. The calculated binding free energies are in excellent agreement with experimental binding constants and reproduce the relative effects of mismatches in the first and second codon position versus a mismatch at the wobble position. The simulations further predict that the Leu2 anticodon stem loop is about 10 times more stable than the Ser stem loop in complex with the Phe UUU codon. It is also found that the ribosome significantly enhances the intrinsic stability differences of codon-anticodon complexes in aqueous solution. Structural analysis of the simulations confirms the previously suggested importance of the universally conserved nucleotides A1492, A1493, and G530 in the decoding process.

Superrepression through Altered Corepressor-Activated Protein:Protein Interactions.

PubMed

He, Chenlu; Custer, Gregory; Wang, Jingheng; Matysiak, Silvina; Beckett, Dorothy

2018-02-20

Small molecules regulate transcription in both eukaryotes and prokaryotes by either enhancing or repressing assembly of transcription regulatory complexes. For allosteric transcription repressors, superrepressor mutants can exhibit increased sensitivity to small molecule corepressors. However, because many transcription regulatory complexes assemble in multiple steps, the superrepressor phenotype can reflect changes in any or all of the individual assembly steps. Escherichia coli biotin operon repression complex assembly, which responds to input biotin concentration, occurs via three coupled equilibria, including corepressor binding, holorepressor dimerization, and binding of the dimer to DNA. A genetic screen has yielded superrepressor mutants that repress biotin operon transcription in vivo at biotin concentrations much lower than those required by the wild type repressor. In this work, isothermal titration calorimetry and sedimentation measurements were used to determine the superrepressor biotin binding and homodimerization properties. The results indicate that, although all variants exhibit biotin binding affinities similar to that measured for BirA wt , five of the six superrepressors show altered homodimerization energetics. Molecular dynamics simulations suggest that the altered dimerization results from perturbation of an electrostatic network that contributes to allosteric activation of BirA for dimerization. Modeling of the multistep repression complex assembly for these proteins reveals that the altered sensitivity of the transcription response to biotin concentration is readily explained solely by the altered superrepressor homodimerization energetics. These results highlight how coupled equilibria enable alterations in a transcription regulatory response to input signal through an indirect mechanism.

Injunctive Norms and Problem Gambling among College Students

PubMed Central

Lostutter, Ty W.; Whiteside, Ursula; Fossos, Nicole; Walker, Denise D.; Larimer, Mary E.

2010-01-01

Two studies examined the relationships among injunctive norms and college student gambling. In study 1 we evaluated the accuracy of perceptions of other students’ approval of gambling and the relationship between perceived approval and gambling behavior. In study 2 we evaluated gambling behavior as a function of perceptions of approval of other students, friends, and family. In study 1, which included 2524 college students, perceptions of other students’ approval of gambling were found to be overestimated and were negatively associated with gambling behavior. The results of study 2, which included 565 college students, replicated the findings of study 1 and revealed positive associations between gambling behavior and perceived approval of friends and family. Results highlight the complexity of injunctive norms and the importance of considering the reference group (e.g., peers, friends, family members) in their evaluation. Results also encourage caution in considering the incorporation of injunctive norms in prevention and intervention approaches. PMID:17394053

Longitudinal relations between adolescents' self-esteem and prosocial behavior toward strangers, friends and family.

PubMed

Fu, Xinyuan; Padilla-Walker, Laura M; Brown, Michael N

2017-06-01

The present study examined age-trends and longitudinal bidirectional relations in self-esteem and prosocial behavior toward strangers, friends, and family over a four-year time period (age 11 to 14). A total of 681 adolescents were recruited in the United States (51% girls, 28% single parent families). A longitudinal panel model was conducted and the results showed that adolescent self-esteem was associated longitudinally with subsequent prosocial behavior toward strangers, and earlier prosocial behavior toward strangers promoted subsequent self-esteem. There were no such bidirectional relations between self-esteem and prosocial behavior toward friends and family. Findings also highlight the complexity of adolescent development of selfesteem and the multidimensional nature of prosocial behavior. Discussion focuses on understanding the dynamic interplay between adolescent selfesteem and prosocial behavior. Copyright © 2017 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Combining high biodiversity with high yields in tropical agroforests.

PubMed

Clough, Yann; Barkmann, Jan; Juhrbandt, Jana; Kessler, Michael; Wanger, Thomas Cherico; Anshary, Alam; Buchori, Damayanti; Cicuzza, Daniele; Darras, Kevin; Putra, Dadang Dwi; Erasmi, Stefan; Pitopang, Ramadhanil; Schmidt, Carsten; Schulze, Christian H; Seidel, Dominik; Steffan-Dewenter, Ingolf; Stenchly, Kathrin; Vidal, Stefan; Weist, Maria; Wielgoss, Arno Christian; Tscharntke, Teja

2011-05-17

Local and landscape-scale agricultural intensification is a major driver of global biodiversity loss. Controversially discussed solutions include wildlife-friendly farming or combining high-intensity farming with land-sparing for nature. Here, we integrate biodiversity and crop productivity data for smallholder cacao in Indonesia to exemplify for tropical agroforests that there is little relationship between yield and biodiversity under current management, opening substantial opportunities for wildlife-friendly management. Species richness of trees, fungi, invertebrates, and vertebrates did not decrease with yield. Moderate shade, adequate labor, and input level can be combined with a complex habitat structure to provide high biodiversity as well as high yields. Although livelihood impacts are held up as a major obstacle for wildlife-friendly farming in the tropics, our results suggest that in some situations, agroforests can be designed to optimize both biodiversity and crop production benefits without adding pressure to convert natural habitat to farmland.

TIGER: A user-friendly interactive grid generation system for complicated turbomachinery and axis-symmetric configurations

NASA Technical Reports Server (NTRS)

Shih, Ming H.; Soni, Bharat K.

1993-01-01

The issue of time efficiency in grid generation is addressed by developing a user friendly graphical interface for interactive/automatic construction of structured grids around complex turbomachinery/axis-symmetric configurations. The accuracy of geometry modeling and its fidelity is accomplished by adapting the nonuniform rational b-spline (NURBS) representation. A customized interactive grid generation code, TIGER, has been developed to facilitate the grid generation process for complicated internal, external, and internal-external turbomachinery fields simulations. The FORMS Library is utilized to build user-friendly graphical interface. The algorithm allows a user to redistribute grid points interactively on curves/surfaces using NURBS formulation with accurate geometric definition. TIGER's features include multiblock, multiduct/shroud, multiblade row, uneven blade count, and patched/overlapping block interfaces. It has been applied to generate grids for various complicated turbomachinery geometries, as well as rocket and missile configurations.

Combining high biodiversity with high yields in tropical agroforests

PubMed Central

Clough, Yann; Barkmann, Jan; Juhrbandt, Jana; Kessler, Michael; Wanger, Thomas Cherico; Anshary, Alam; Buchori, Damayanti; Cicuzza, Daniele; Darras, Kevin; Putra, Dadang Dwi; Erasmi, Stefan; Pitopang, Ramadhanil; Schmidt, Carsten; Schulze, Christian H.; Seidel, Dominik; Steffan-Dewenter, Ingolf; Stenchly, Kathrin; Vidal, Stefan; Weist, Maria; Wielgoss, Arno Christian; Tscharntke, Teja

2011-01-01

Local and landscape-scale agricultural intensification is a major driver of global biodiversity loss. Controversially discussed solutions include wildlife-friendly farming or combining high-intensity farming with land-sparing for nature. Here, we integrate biodiversity and crop productivity data for smallholder cacao in Indonesia to exemplify for tropical agroforests that there is little relationship between yield and biodiversity under current management, opening substantial opportunities for wildlife-friendly management. Species richness of trees, fungi, invertebrates, and vertebrates did not decrease with yield. Moderate shade, adequate labor, and input level can be combined with a complex habitat structure to provide high biodiversity as well as high yields. Although livelihood impacts are held up as a major obstacle for wildlife-friendly farming in the tropics, our results suggest that in some situations, agroforests can be designed to optimize both biodiversity and crop production benefits without adding pressure to convert natural habitat to farmland. PMID:21536873

An energetics-based honeybee nectar-foraging model used to assess the potential for landscape-level pesticide exposure dilution

PubMed Central

Focks, Andreas; Belgers, Dick; van der Steen, Jozef J.M.; Boesten, Jos J.T.I.; Roessink, Ivo

2016-01-01

Estimating the exposure of honeybees to pesticides on a landscape scale requires models of their spatial foraging behaviour. For this purpose, we developed a mechanistic, energetics-based model for a single day of nectar foraging in complex landscape mosaics. Net energetic efficiency determined resource patch choice. In one version of the model a single optimal patch was selected each hour. In another version, recruitment of foragers was simulated and several patches could be exploited simultaneously. Resource availability changed during the day due to depletion and/or intrinsic properties of the resource (anthesis). The model accounted for the impact of patch distance and size, resource depletion and replenishment, competition with other nectar foragers, and seasonal and diurnal patterns in availability of nectar-providing crops and wild flowers. From the model we derived simple rules for resource patch selection, e.g., for landscapes with mass-flowering crops only, net energetic efficiency would be proportional to the ratio of the energetic content of the nectar divided by distance to the hive. We also determined maximum distances at which resources like oilseed rape and clover were still energetically attractive. We used the model to assess the potential for pesticide exposure dilution in landscapes of different composition and complexity. Dilution means a lower concentration in nectar arriving at the hive compared to the concentration in nectar at a treated field and can result from foraging effort being diverted away from treated fields. Applying the model for all possible hive locations over a large area, distributions of dilution factors were obtained that were characterised by their 90-percentile value. For an area for which detailed spatial data on crops and off-field semi-natural habitats were available, we tested three landscape management scenarios that were expected to lead to exposure dilution: providing alternative resources than the target crop (oilseed rape) in the form of (i) other untreated crop fields, (ii) flower strips of different widths at field edges (off-crop in-field resources), and (iii) resources on off-field (semi-natural) habitats. For both model versions, significant dilution occurred only when alternative resource patches were equal or more attractive than oilseed rape, nearby and numerous and only in case of flower strips and off-field habitats. On an area-base, flower strips were more than one order of magnitude more effective than off-field habitats, the main reason being that flower strips had an optimal location. The two model versions differed in the predicted number of resource patches exploited over the day, but mainly in landscapes with numerous small resource patches. In landscapes consisting of few large resource patches (crop fields) both versions predicted the use of a small number of patches. PMID:27602273

Modeling Whistler Wave Generation Regimes In Magnetospheric Cyclotron Maser

NASA Astrophysics Data System (ADS)

Pasmanik, D. L.; Demekhov, A. G.; Trakhtengerts, V. Y.; Parrot, M.

Numerical analysis of the model for cyclotron instability development in the Earth magnetosphere is made.This model, based on the self-consistent set of equations of quasi-linear plasma theory, describes different regimes of wave generation and related energetic particle precipitation. As the source of free energy the injection of energetic electrons with transverse anisotropic distribution function to the interaction region is considered. Two different mechanisms of energetic electron loss from the interaction region are discussed. The first one is precipitation of energetic particles via the loss cone. The other mechanism is drift of particles away from the interaction region across the mag- netic field line. In the case of interaction in plasmasphere or rather large areas of cold plasma density enhancement the loss cone precipitation are dominant. For interaction in a subauroral duct losses due to drift are most effective. A parametric study of the model for both mechanisms of particle losses is made. The main attention is paid to the analysis of generation regimes for different characteristics of energetic electron source, such as the shape of pitch-angle distributions and elec- tron density. We show that in addition to the well-known stationary generation and periodic regime with successive spikes of similar shape, more complex forms of wave spectrum exist. In particular, we found a periodic regime, in which a single period in- cludes two separate spikes with different spectral shapes. In another regime, periodic generation of spikes at higher frequencies together with quasi-stationary generation at lower frequencies occurs. Quasi-periodic regime with spike overlapping, i.e. when generation of a new spike begins before the previous one is over is also found. Results obtained are compared with experimental data on quasi-periodic regimes of whistler wave generation.

An Energetic Concept of Habitability for the Deep Subsurface

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.

2006-01-01

Universally, life must be characterized by a characteristic level of order and complexity. In the most general sense, habitability could then be defined as the set of factors required to allow the creation and maintenance of molecular complexity. These factors are: chemical raw materials; energy with which to assemble those materials into complex molecules and sustain the resultant state of complexity; a solvent that allows the interaction of complex molecules, promotes tertiary structure, and permits compartmentalization; and environmental conditions that permit the assembly and maintenance of complex molecules. On Earth, these general requirements correspond to the major biogenic elements C, H, O, N, P, S; chemical or light energy; the solvent water; and specific ranges of temperature, pH, radiation, ionic strength, and so forth, which have thus far been determined on and exclusively empirical basis. Importantly, while the complete absence of any of these factors ensures uninhabitable conditions, the mere presence of all four does not guarantee habitability. In each case - even that of water - it is a question of degree. This question can be couched in quantitative terms by considering the impact of each of these factors on cellular energy balance. More "extreme" conditions (e.g., high temperature, high or low pH, etc.), lower water activity, and low concentrations of nutrients incur or have potential to be addressed by increased investment of energy on the part of the cell. This must be balanced by energy conservation in the cell, noting that biochemical, mass transport, and abiotic chemical limitations intervene between environmental energy availability and biological energy capture. Similarly, lower boundary conditions are emplaced on useful environmental energy yields by the "quantized" nature of biological energy conservation, and upper boundary conditions are emplaced by energy levels or fluxes that are destructive with respect to complexity. This energetic framework, with boundary conditions supplied by the specifics of the biochemistry in question, offers a generalized, yet quantitative means of assessing the habitability of any system with respect to complex life.

Quantitative tests of a reconstitution model for RNA folding thermodynamics and kinetics.

PubMed

Bisaria, Namita; Greenfeld, Max; Limouse, Charles; Mabuchi, Hideo; Herschlag, Daniel

2017-09-12

Decades of study of the architecture and function of structured RNAs have led to the perspective that RNA tertiary structure is modular, made of locally stable domains that retain their structure across RNAs. We formalize a hypothesis inspired by this modularity-that RNA folding thermodynamics and kinetics can be quantitatively predicted from separable energetic contributions of the individual components of a complex RNA. This reconstitution hypothesis considers RNA tertiary folding in terms of ΔG align , the probability of aligning tertiary contact partners, and ΔG tert , the favorable energetic contribution from the formation of tertiary contacts in an aligned state. This hypothesis predicts that changes in the alignment of tertiary contacts from different connecting helices and junctions (ΔG HJH ) or from changes in the electrostatic environment (ΔG +/- ) will not affect the energetic perturbation from a mutation in a tertiary contact (ΔΔG tert ). Consistent with these predictions, single-molecule FRET measurements of folding of model RNAs revealed constant ΔΔG tert values for mutations in a tertiary contact embedded in different structural contexts and under different electrostatic conditions. The kinetic effects of these mutations provide further support for modular behavior of RNA elements and suggest that tertiary mutations may be used to identify rate-limiting steps and dissect folding and assembly pathways for complex RNAs. Overall, our model and results are foundational for a predictive understanding of RNA folding that will allow manipulation of RNA folding thermodynamics and kinetics. Conversely, the approaches herein can identify cases where an independent, additive model cannot be applied and so require additional investigation.

Structural and energetic study of cation-π-cation interactions in proteins.

PubMed

Pinheiro, Silvana; Soteras, Ignacio; Gelpí, Josep Lluis; Dehez, François; Chipot, Christophe; Luque, F Javier; Curutchet, Carles

2017-04-12

Cation-π interactions of aromatic rings and positively charged groups are among the most important interactions in structural biology. The role and energetic characteristics of these interactions are well established. However, the occurrence of cation-π-cation interactions is an unexpected motif, which raises intriguing questions about its functional role in proteins. We present a statistical analysis of the occurrence, composition and geometrical preferences of cation-π-cation interactions identified in a set of non-redundant protein structures taken from the Protein Data Bank. Our results demonstrate that this structural motif is observed at a small, albeit non-negligible frequency in proteins, and suggest a preference to establish cation-π-cation motifs with Trp, followed by Tyr and Phe. Furthermore, we have found that cation-π-cation interactions tend to be highly conserved, which supports their structural or functional role. Finally, we have performed an energetic analysis of a representative subset of cation-π-cation complexes combining quantum-chemical and continuum solvation calculations. Our results point out that the protein environment can strongly screen the cation-cation repulsion, leading to an attractive interaction in 64% of the complexes analyzed. Together with the high degree of conservation observed, these results suggest a potential stabilizing role in the protein fold, as demonstrated recently for a miniature protein (Craven et al., J. Am. Chem. Soc. 2016, 138, 1543). From a computational point of view, the significant contribution of non-additive three-body terms challenges the suitability of standard additive force fields for describing cation-π-cation motifs in molecular simulations.

Eureka: Six Easy Steps to Research Success

ERIC Educational Resources Information Center

Hubel, Joy Alter

2005-01-01

Eureka is similar to the Big6(super TM) research skills by Michael Eisenberg and Bob Berkowitz, as both methods simplify the complex process of critical information gathering into six user-friendly steps. The six research steps to Eureka are presented.

The Role of Gender and Friends’ Gender on Peer Socialization of Adolescent Drinking: A Prospective Multilevel Social Network Analysis

PubMed Central

Steinley, Douglas; Slutske, Wendy S.

2014-01-01

Although socializing effects of friends’ drinking on adolescent drinking behavior have been firmly established in previous literature, study results on the importance of gender, as well as the specific role that gender may play in peer socialization, are very mixed. Given the increasing importance of gender in friendships (particularly opposite-sex friendships) during adolescence, it is necessary to better understand the nuanced roles that gender can play in peer socialization effects on alcohol use. In addition, previous studies focusing on the interplay between individual gender and friends’ gender have been largely dyadic; less is known about potential gendered effects of broader social networks. The current study sought to further investigate potential effects of gender on friends’ influence on adolescent drinking behavior with particular emphasis on the number of same-sex and opposite-sex friends within one’s friendship network, as well as closeness to these friends. Using Waves I and II of the saturated sample of the National Longitudinal Study of Adolescent Health (Add Health), adolescent friendship networks were used to calculate the mean drinking behaviors of adolescent friends. Multi-level models estimated the effects of individual drinking behaviors, friend drinking behaviors, and school-level drinking behaviors on adolescent drinking 1 year later, as well as moderating effects of gender composition of friendship groups and male and female friend closeness on the relationship between friends’ drinking behaviors and adolescent drinking behavior. Results documented that gender composition of friendship groups did not influence the effect of friends’ drinking on individual drinking 1 year later. However, closeness to friends did influence this relationship. As closeness to male friends decreased, the influence of their drinking behavior increased, for both boys and girls. A similar effect was found for female friends, but only for boys. Female friend closeness did not affect the relationship between peer alcohol socialization and girls’ alcohol use. The findings indicate that the role of gender on alcohol socialization may be more complex than previously thought, particularly when examining the potential role that alcohol use may play as a mechanism for social bonding within opposite-sex friendships and same-sex male friendships. PMID:24170437

Advances in understanding the molecular basis of the first steps in color vision

PubMed Central

Hofmann, Lukas; Palczewski, Krzysztof

2015-01-01

Serving as one of our primary environmental inputs, vision is the most sophisticated sensory system in humans. Here, we present recent findings derived from energetics, genetics and physiology that provide a more advanced understanding of color perception in mammals. Energetics of cis–trans isomerization of 11-cis-retinal accounts for color perception in the narrow region of the electromagnetic spectrum and how human eyes can absorb light in the near infrared (IR) range. Structural homology models of visual pigments reveal complex interactions of the protein moieties with the light sensitive chromophore 11-cis-retinal and that certain color blinding mutations impair secondary structural elements of these G protein-coupled receptors (GPCRs). Finally, we identify unsolved critical aspects of color tuning that require future investigation. PMID:26187035

Nanostructure Formation by controlled dewetting on patterned substrates: A combined theoretical, modeling and experimental study.

PubMed

Lu, Liang-Xing; Wang, Ying-Min; Srinivasan, Bharathi Madurai; Asbahi, Mohamed; Yang, Joel K W; Zhang, Yong-Wei

2016-09-01

We perform systematic two-dimensional energetic analysis to study the stability of various nanostructures formed by dewetting solid films deposited on patterned substrates. Our analytical results show that by controlling system parameters such as the substrate surface pattern, film thickness and wetting angle, a variety of equilibrium nanostructures can be obtained. Phase diagrams are presented to show the complex relations between these system parameters and various nanostructure morphologies. We further carry out both phase field simulations and dewetting experiments to validate the analytically derived phase diagrams. Good agreements between the results from our energetic analyses and those from our phase field simulations and experiments verify our analysis. Hence, the phase diagrams presented here provide guidelines for using solid-state dewetting as a tool to achieve various nanostructures.

Interaction between solar energetic particles and interplanetary grains

NASA Astrophysics Data System (ADS)

Strazzulla, G.; Calcagno, L.; Foti, G.; Sheng, K. L.

Some laboratory-studied effects induced by the fluence of fast ions on frosts of astrophysical interest are summarized. The results are applied to the interaction between energetic solar ions and interplanetary dust grains assumed to be cometary debris which spends about one-million yr before being collected in the earth's atmosphere or colliding on the moon's surface. The importance of erosion by particles to the stability of ice grains is confirmed. The build up of carbonaceous material by ion fluence on hydrocarbon containing grains is discussed. It is suggested that these new materials could be the glue which cements submicron silicate particles to form a complex agglomeration whose density increases with increasing proton fluence (packing effect). The IR spectra of laboratory synthesized carbonaceous material are compared with those observed in some carbonaceous meteoritic extracts.

An ab initio molecular orbital study of the mechanism for the gas-phase water-mediated decomposition and the formation of hydrates of peroxyacetyl nitrate (PAN).

PubMed

Li, Yumin; Francisco, Joseph S

2005-08-31

There is uncertainty in the mechanism for the hydrolysis of peroxyacetyl nitrate (PAN), and experimental attempts to detect products of the direct reaction have been unsuccessful. Ab initio calculations are used to examine the energetics of water-mediated decomposition of gas-phase PAN into acetic acid and peroxynitric acid. On the basis of ab initio calculations, an alternative reaction mechanism for the decomposition of PAN is proposed. The calculations indicate that the barrier for one water addition to PAN is large. However, including additional water molecules reveals a substantially lower energy route. The calculations suggest that the formation of PAN hydrate complexes are energetically favorable and stable. Additional waters are increasingly efficient at stabilizing hydrated PAN.

Barriers, facilitators, and recommendations related to implementing the Baby-Friendly Initiative (BFI): an integrative review.

PubMed

Semenic, Sonia; Childerhose, Janet E; Lauzière, Julie; Groleau, Danielle

2012-08-01

Despite growing evidence for the positive impact of the Baby-Friendly Initiative (BFI) on breastfeeding outcomes, few studies have investigated the barriers and facilitators to the implementation of Baby-Friendly practices that can be used to improve uptake of the BFI at the local or country levels. This integrative review aimed to identify and synthesize information on the barriers, facilitators, and recommendations related to the BFI from the international, peer-reviewed literature. Thirteen databases were searched using the keywords Baby Friendly, Baby-Friendly Hospital Initiative, BFI, BFHI, Ten Steps, implementation, adoption, barriers, facilitators, and their combinations. A total of 45 English-language articles from 16 different countries met the inclusion criteria for the review. Data analysis was guided by Cooper's five stages of integrative research review. Using a multiple intervention program framework, findings were categorized into sociopolitical, organizational-level, and individual-level barriers and facilitators to implementing the BFI, as well as intra-, inter-, and extraorganizational recommendations for strengthening BFI implementation. A wide variety of obstacles and potential solutions to BFI implementation were identified. Findings suggest some priority issues to address when pursuing Baby-Friendly designation, including the endorsements of both local administrators and governmental policy makers, effective leadership of the practice change process, health care worker training, the marketing influence of formula companies, and integrating hospital and community health services. Framing the BFI as a complex, multilevel, evidence-based change process and using context-focused research implementation models to guide BFI implementation efforts may help identify effective strategies for promoting wider adoption of the BFI in health services.

Investigating the Effect of Nanoscale Changes on the Chemistry and Energetics of Nanocrystals with a Novel Photoemission Spectroscopy Methodology

NASA Astrophysics Data System (ADS)

Liao, Michael W.

This dissertation explores the effect of nanometer-scale changes in structure on the energetics of photocatalytic and photovoltaic materials. Of particular interest are semiconductor nanocrystals (NCs), which have interesting chemical properties that lead to novel structures and applications. Chief among these properties are quantum confinement and the high surface area-to-volume ratio, which allow for chemical tuning of the energetics and structure of NCs. This tunable energetic landscape has led to increasing application of NCs in various areas of research, including solar energy conversion, light-emitting diode technologies, and photocatalysis. However, spectroscopic methods to determine the energetics of NCs have not been well developed, due to chemical complexities of relevant NCs such as polydispersity, capping ligand effects, core-shell structures, and other chemical modifications. In this work, we demonstrate and expand the utility of photoelectron spectroscopy (PES) to probe the energetics of NCs by considering the physical processes that lead to background and secondary photoemission to enhance photoemission from the sample of interest. A new methodology for the interpretation of UP spectra was devised in order to emphasize the minute changes to the UP spectra line shape that arise from nanoscopic changes to the NCs. We applied various established subtractions that correct for photon source satellites, secondary photoelectrons, and substrate photoemission. We then investigated the effect of ligand surface coverage on the surface chemistry and density of states at the top of valence band (VB). We systematically removed ligands by increasing numbers of purification steps for two diameters of NCs and found that doing so increased photoemission density at the top of the VB, which is due to undercoordinated surface atoms. Deeper VB structure was also altered, possibly due to reorganization of the atoms in the NC. Using the new UPS interpretation methodology, we examined the evolution of the valence band energy (EVB) of CdSe NCs as it was modified from spherical NC to rod to Au-NP tipped nanorod (NR). We also employed potential-modulated attenuated total reflectance spectroscopy (PM-ATR) to probe the conduction band energy (ECB) of the series. The EVB decreased with each modification, which is predicted with a band-bending model. This trend was also observed in the ECB, as revealed by spectroelectrochemistry, along with the appearance of new metal-semiconductor states in the band gap. UPS was finally used to investigate the even more complex Pt-NP tipped CdSe CdS core shell NR heterostructure. The addition of the CdS shell decreases the EVB relative to CdSe, as expected from common cation II-VI compounds. The Pt-NC increases the EVB, which, like the Au-CdSe NR, is predicted by employing a band-bending model. XPS revealed that PtSx-like chemical states were formed near the CdS-Pt interface. These experiments, along with the improved UP spectra interpretation methodology, demonstrate the wealth of information regarding surface chemistry and energetics that can be obtained with PES which can be applied to not only NCs, but also to metal oxide or molecular thin films.

Exploring Identity and Citizenship in a Virtual World

ERIC Educational Resources Information Center

Martin, Stewart

2012-01-01

Digital technology is able to modify deep-rooted views (Martin & Vallance, 2008) and facilitate identity articulation (Bers, 2001). During adolescence young people are developing their personal identity framed through the context of family, friends and cultural and religious inheritance. The complex dynamics between…

Adolescent health care maintenance in a teen-friendly clinic.

PubMed

Chaisson, Nicole; Shore, William B

2014-09-01

Adolescence is marked by complex physical, cognitive, social, and emotional development, which can be stressful for families and adolescents. Before the onset of puberty, providers should clearly lay the groundwork for clinical care and office visits during the adolescent years. This article addresses the guidelines and current legal standards for confidentiality in adolescent care, the most frequently used psychosocial screening tools, and current recommendations for preventive health services and immunizations. Through the creation of teen-friendly clinics, primary care providers are well positioned to offer guidance and support to teens and their parents during this time of transition and growth. Copyright © 2014 Elsevier Inc. All rights reserved.

DFT Analysis of Spin Crossover in Mn(III) Complexes: Is a Two-Electron S = 2 to S = 0 Spin Transition Feasible?

PubMed

Amabilino, Silvia; Deeth, Robert J

2017-03-06

Six-coordinate, rigorously octahedral d 4 Mn(III) spin crossover (SCO) complexes are limited by symmetry to an S = 1 (intermediate spin, IS) to S = 2 (high spin, HS) transition. In order to realize the potential S = 0 to S = 2 transition, a lower symmetry and/or change in coordination number is needed, which we explore here computationally. First, a number of complexes are analyzed to develop a reliable and relatively fast DFT protocol for reproducing known Mn(III) spin state energetics. The hybrid meta-GGA functional TPSSh with a modest split valence plus polarization basis set and an empirical dispersion correction is found to predict correctly the ground spin state of Mn(III) complexes, including true low-spin (LS) S = 0 systems, with a range of donor sets including the hexadentate [N 4 O 2 ] Schiff base ligands. The electronic structure design criteria necessary for realizing a ΔS = 2 SCO transition are described, and a number of model complexes are screened for potential SCO behavior. Five-coordinate trigonal-bipyramidal symmetry fails to yield any suitable systems. Seven-coordinate, approximately pentagonal bipyramidal symmetry is more favorable, and when a known pentadentate macrocyclic donor is combined with π-acceptor axial ligands, a novel Mn(III) complex, [Mn(PABODP)(PF 3 ) 2 ] 3+ (PABODP = 2,13-dimethyl-3,6,9,12,18-pentaazabicyclo[12.3.1]octadeca-1(18),2,12,14,16-pentaene), is predicted to have the right spin state energetics for an S = 0 to S = 2 transition. Successful synthesis of such a complex could provide the first example of a ΔS = 2 SCO transition for d 4 Mn(III). However, the combination of a rigid macrocycle and a high coordination number dilutes the stereochemical activity of the d electrons, leading to relatively small structural changes between HS and LS systems. It may therefore remain a challenge to realize strong cooperative effects in Mn(III) systems.

A CU-Level Rate and Distortion Estimation Scheme for RDO of Hardware-Friendly HEVC Encoders Using Low-Complexity Integer DCTs.

PubMed

Lee, Bumshik; Kim, Munchurl

2016-08-01

In this paper, a low complexity coding unit (CU)-level rate and distortion estimation scheme is proposed for High Efficiency Video Coding (HEVC) hardware-friendly implementation where a Walsh-Hadamard transform (WHT)-based low-complexity integer discrete cosine transform (DCT) is employed for distortion estimation. Since HEVC adopts quadtree structures of coding blocks with hierarchical coding depths, it becomes more difficult to estimate accurate rate and distortion values without actually performing transform, quantization, inverse transform, de-quantization, and entropy coding. Furthermore, DCT for rate-distortion optimization (RDO) is computationally high, because it requires a number of multiplication and addition operations for various transform block sizes of 4-, 8-, 16-, and 32-orders and requires recursive computations to decide the optimal depths of CU or transform unit. Therefore, full RDO-based encoding is highly complex, especially for low-power implementation of HEVC encoders. In this paper, a rate and distortion estimation scheme is proposed in CU levels based on a low-complexity integer DCT that can be computed in terms of WHT whose coefficients are produced in prediction stages. For rate and distortion estimation in CU levels, two orthogonal matrices of 4×4 and 8×8 , which are applied to WHT that are newly designed in a butterfly structure only with addition and shift operations. By applying the integer DCT based on the WHT and newly designed transforms in each CU block, the texture rate can precisely be estimated after quantization using the number of non-zero quantized coefficients and the distortion can also be precisely estimated in transform domain without de-quantization and inverse transform required. In addition, a non-texture rate estimation is proposed by using a pseudoentropy code to obtain accurate total rate estimates. The proposed rate and the distortion estimation scheme can effectively be used for HW-friendly implementation of HEVC encoders with 9.8% loss over HEVC full RDO, which much less than 20.3% and 30.2% loss of a conventional approach and Hadamard-only scheme, respectively.

Glutaredoxin-2 is required to control oxidative phosphorylation in cardiac muscle by mediating deglutathionylation reactions.

PubMed

Mailloux, Ryan J; Xuan, Jian Ying; McBride, Skye; Maharsy, Wael; Thorn, Stephanie; Holterman, Chet E; Kennedy, Christopher R J; Rippstein, Peter; deKemp, Robert; da Silva, Jean; Nemer, Mona; Lou, Marjorie; Harper, Mary-Ellen

2014-05-23

Glutaredoxin-2 (Grx2) modulates the activity of several mitochondrial proteins in cardiac tissue by catalyzing deglutathionylation reactions. However, it remains uncertain whether Grx2 is required to control mitochondrial ATP output in heart. Here, we report that Grx2 plays a vital role modulating mitochondrial energetics and heart physiology by mediating the deglutathionylation of mitochondrial proteins. Deletion of Grx2 (Grx2(-/-)) decreased ATP production by complex I-linked substrates to half that in wild type (WT) mitochondria. Decreased respiration was associated with increased complex I glutathionylation diminishing its activity. Tissue glucose uptake was concomitantly increased. Mitochondrial ATP output and complex I activity could be recovered by restoring the redox environment to that favoring the deglutathionylated states of proteins. Grx2(-/-) hearts also developed left ventricular hypertrophy and fibrosis, and mice became hypertensive. Mitochondrial energetics from Grx2 heterozygotes (Grx2(+/-)) were also dysfunctional, and hearts were hypertrophic. Intriguingly, Grx2(+/-) mice were far less hypertensive than Grx2(-/-) mice. Thus, Grx2 plays a vital role in modulating mitochondrial metabolism in cardiac muscle, and Grx2 deficiency leads to pathology. As mitochondrial ATP production was restored by the addition of reductants, these findings may be relevant to novel redox-related therapies in cardiac disease. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Rapid and direct synthesis of complex perovskite oxides through a highly energetic planetary milling

PubMed Central

Lee, Gyoung-Ja; Park, Eun-Kwang; Yang, Sun-A; Park, Jin-Ju; Bu, Sang-Don; Lee, Min-Ku

2017-01-01

The search for a new and facile synthetic route that is simple, economical and environmentally safe is one of the most challenging issues related to the synthesis of functional complex oxides. Herein, we report the expeditious synthesis of single-phase perovskite oxides by a high-rate mechanochemical reaction, which is generally difficult through conventional milling methods. With the help of a highly energetic planetary ball mill, lead-free piezoelectric perovskite oxides of (Bi, Na)TiO3, (K, Na)NbO3 and their modified complex compositions were directly synthesized with low contamination. The reaction time necessary to fully convert the micron-sized reactant powder mixture into a single-phase perovskite structure was markedly short at only 30–40 min regardless of the chemical composition. The cumulative kinetic energy required to overtake the activation period necessary for predominant formation of perovskite products was ca. 387 kJ/g for (Bi, Na)TiO3 and ca. 580 kJ/g for (K, Na)NbO3. The mechanochemically derived powders, when sintered, showed piezoelectric performance capabilities comparable to those of powders obtained by conventional solid-state reaction processes. The observed mechanochemical synthetic route may lead to the realization of a rapid, one-step preparation method by which to create other promising functional oxides without time-consuming homogenization and high-temperature calcination powder procedures. PMID:28387324

Social Identity Complexity, Cross-ethnic Friendships, and Intergroup Attitudes in Urban Middle Schools

PubMed Central

Knifsend, Casey A.; Juvonen, Jaana

2013-01-01

The current study investigated contextual antecedents (i.e., cross-ethnic peers and friends) and correlates (i.e., intergroup attitudes) of social identity complexity in seventh grade. Social identity complexity refers to the perceived overlap among social groups with which youth identify. Identifying mostly with out-of-school sports, religious affiliations, and peer crowds, the ethnically diverse sample (N = 622; Mage in seventh grade = 12.56) showed moderately high complexity. Social identity complexity mediated the link between cross-ethnic friendships and ethnic intergroup attitudes, but only when adolescents had a high proportion of cross-ethnic peers at school. Results are discussed in terms of how school diversity can promote complex social identities and positive intergroup attitudes. PMID:24032401

Navigating complexity to breed disease-resistant crops

USDA-ARS?s Scientific Manuscript database

Crop losses due to disease constitute a burden to global food security and agricultural sustainability. The use of genetic resistance is an environmentally-friendly way to reduce these losses. This paper considers the insights derived from various lines of research on disease resistance and manageme...

Microcomputers, Model Rockets, and Race Cars.

ERIC Educational Resources Information Center

Mirus, Edward A., Jr.

1985-01-01

The industrial education orientation program at Wisconsin School for the Deaf (WSD) presents problem-solving situations to all seventh- and eighth-grade hearing-impaired students. WSD developed user-friendly microcomputer software to guide students individually through complex computations involving model race cars and rockets while freeing…

Phytofilter - environmental friendly solution for purification of surface plate from urbanized territories

NASA Astrophysics Data System (ADS)

Ruchkinova, O.; Shchuckin, I.

2017-06-01

Its proved, that phytofilters are environmental friendly solution of problem of purification of surface plate from urbanized territories. Phytofilters answer the nowadays purposes to systems of purification of land drainage. The main problem of it is restrictions, connecter with its use in the conditions of cold temperature. Manufactured a technology and mechanism, which provide a whole-year purification of surface plate and its storage. Experimentally stated optimal makeup of filtering load: peat, zeolite and sand in per cent of volume, which provides defined hydraulic characteristics. Stated sorbate and ion-selective volume of complex filtering load of ordered composition in dynamic conditions. Estimated dependences of exit concentrations of oil products and heavy metals on temperature by filtering through complex filtering load of ordered composition. Defined effectiveness of purification at phytofiltering installation. Fixed an influence of embryophytes on process of phytogeneration and capacity of filtering load. Recommended swamp iris, mace reed and reed grass. Manufactured phytofilter calculation methodology. Calculated economic effect from use of phytofiltration technology in comparison with traditional block-modular installations.

Presentation of the project "An investigation of the early stages of solar eruptions - from remote observations to energetic particles"

NASA Astrophysics Data System (ADS)

Kozarev, Kamen; Veronig, Astrid; Duchlev, Peter; Koleva, Kostadinka; Dechev, Momchil; Miteva, Rositsa; Temmer, Manuela; Dissauer, Karin

2017-11-01

Coronal mass ejections (CMEs), one of the most energetic manifestations of solar activity, are complex events, which combine multiple related phenomena occurring on the solar surface, in the extended solar atmosphere (corona), as well as in interplanetary space. We present here an outline of a new collaborative project between scientists from the Bulgarian Academy of Sciences (BAS), Bulgaria and the University of Graz, Austria. The goal of the this research project is to answer the following questions: 1) What are the properties of erupting filaments, CMEs, and CME-driven shock waves near the Sun, and of associated solar energetic particle (SEP) fluxes in interplanetary space? 2) How are these properties related to the coronal acceleration of SEPs? To achieve the scientific goals of this project, we will use remote solar observations with high spatial and temporal resolution to characterize the early stages of coronal eruption events in a systematic way - studying the pre-eruptive behavior of filaments and flares during energy build-up, the kinematics and morphology of CMEs and compressive shock waves, and the signatures of high energy non-thermal particles in both remote and in situ observations.

Validated Predictions of Metabolic Energy Consumption for Submaximal Effort Movement

PubMed Central

Tsianos, George A.; MacFadden, Lisa N.

2016-01-01

Physical performance emerges from complex interactions among many physiological systems that are largely driven by the metabolic energy demanded. Quantifying metabolic demand is an essential step for revealing the many mechanisms of physical performance decrement, but accurate predictive models do not exist. The goal of this study was to investigate if a recently developed model of muscle energetics and force could be extended to reproduce the kinematics, kinetics, and metabolic demand of submaximal effort movement. Upright dynamic knee extension against various levels of ergometer load was simulated. Task energetics were estimated by combining the model of muscle contraction with validated models of lower limb musculotendon paths and segment dynamics. A genetic algorithm was used to compute the muscle excitations that reproduced the movement with the lowest energetic cost, which was determined to be an appropriate criterion for this task. Model predictions of oxygen uptake rate (VO2) were well within experimental variability for the range over which the model parameters were confidently known. The model's accurate estimates of metabolic demand make it useful for assessing the likelihood and severity of physical performance decrement for a given task as well as investigating underlying physiologic mechanisms. PMID:27248429

Coarse gaining of molecular crystals: limitations imposed by molecular flexibility

NASA Astrophysics Data System (ADS)

Picu, Catalin; Pal, Anirban

Molecular crystals include molecular electronics, energetic materials, pharmaceuticals and some food components. In many of these applications the small scale mechanical behavior of the crystal is important such as for example in energetic materials where detonation is induced by the formation of hot spots which are induced thermomechanically, and in pharmaceuticals where phase stability is critical for the biochemical activity of the drug. Accurate modeling of these processes requires resolving the atomistic scale details of the material. However, the cost of these models is very large due to the complexity of the molecules forming the crystal, and some form of coarse graning is necessary. In this study we identify the limitations imposed by the need to accurately capture molecular flexibility on the development of coarse grained models for the energetic molecular crystal RDX. We define guidelines for the definition of coarse grained models that target elastic and plastic crystal scale properties such as elastic constants, thermal expansion, compressibility, the critical stress for the motion of dislocations (Peierls stress) and the stacking fault energy This work was supported by the ARO through Grant W911NF-09-1-0330 and AFRL through Grant FA8651-16-1-0004.

Space Environment Information System (SPENVIS)

NASA Astrophysics Data System (ADS)

Kruglanski, M.; Messios, N.; de Donder, E.; Gamby, E.; Calders, S.; Hetey, L.; Evans, H.

2009-04-01

SPENVIS is an ESA operational software developed and maintained at BIRA-IASB since 1996. It provides standardized access to most of the recent models of the hazardous space environment, through a user-friendly Web interface (http://www.spenvis.oma.be/). The system allows spacecraft engineers to perform a rapid analysis of environmental problems related to natural radiation belts, solar energetic particles, cosmic rays, plasmas, gases, magnetic fields and micro-particles. Various reporting and graphical utilities and extensive help facilities are included to allow engineers with relatively little familiarity to produce reliable results. SPENVIS also contains an active, integrated version of the ECSS Space Environment Standard and access to in-flight data on the space environment. Although SPENVIS in the first place is designed to help spacecraft engineers, it is also used by technical universities in their educational programs. At present more than 4000 users are registered. With SPENVIS, one can generate a spacecraft trajectory or a coordinate grid and then calculate: geomagnetic coordinates; trapped proton and electron fluxes; solar proton fluences; cosmic ray fluxes; radiation doses (ionising and non-ionising) for simple geometries; a sectoring analysis for dose calculations in more complex geometries; damage equivalent fluences for Si, GaAs and multi-junction solar cells; Geant4 Monte Carlo analysis for doses and pulse height rates in planar and spherical shields; ion LET and flux spectra and single event upset rates; trapped proton flux anisotropy; atmospheric and ionospheric densities and temperatures; atomic oxygen erosion depths; surface and internal charging characteristics; solar array current collections and power losses; wall damage. The new version of SPENVIS (to be released in January 2009) also allows mission analysis for Mars and Jupiter.

Atomistic modelling of scattering data in the Collaborative Computational Project for Small Angle Scattering (CCP-SAS)

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

Perkins, Stephen J.; Wright, David W.; Zhang, Hailiang

2016-10-14

The capabilities of current computer simulations provide a unique opportunity to model small-angle scattering (SAS) data at the atomistic level, and to include other structural constraints ranging from molecular and atomistic energetics to crystallography, electron microscopy and NMR. This extends the capabilities of solution scattering and provides deeper insights into the physics and chemistry of the systems studied. Realizing this potential, however, requires integrating the experimental data with a new generation of modelling software. To achieve this, the CCP-SAS collaboration (http://www.ccpsas.org/) is developing open-source, high-throughput and user-friendly software for the atomistic and coarse-grained molecular modelling of scattering data. Robust state-of-the-artmore » molecular simulation engines and molecular dynamics and Monte Carlo force fields provide constraints to the solution structure inferred from the small-angle scattering data, which incorporates the known physical chemistry of the system. The implementation of this software suite involves a tiered approach in whichGenAppprovides the deployment infrastructure for running applications on both standard and high-performance computing hardware, andSASSIEprovides a workflow framework into which modules can be plugged to prepare structures, carry out simulations, calculate theoretical scattering data and compare results with experimental data.GenAppproduces the accessible web-based front end termedSASSIE-web, andGenAppandSASSIEalso make community SAS codes available. Applications are illustrated by case studies: (i) inter-domain flexibility in two- to six-domain proteins as exemplified by HIV-1 Gag, MASP and ubiquitin; (ii) the hinge conformation in human IgG2 and IgA1 antibodies; (iii) the complex formed between a hexameric protein Hfq and mRNA; and (iv) synthetic `bottlebrush' polymers.« less

Near-real time forecasts of MeV protons based on sub-relativistic electrons: communicating the outputs to the end users

NASA Astrophysics Data System (ADS)

Sarlanis, Christos; Heber, Bernd; Labrenz, Johannes; Kühl, Patrick; Marquardt, Johannes; Dimitroulakos, John; Papaioannou, Athanasios; Posner, Arik

2017-04-01

Solar Energetic Particle (SEP) events are one of the most important elements of space weather. Given that the complexity of the underlying physical processes of the acceleration and propagation of SEP events is still a very active research area, the prognosis of SEP event occurrence and their corresponding characteristics remains challenging. In order to provide up to an hour warning time before these particles arrive at Earth, relativistic electron and below 50 MeV proton data from the Electron Proton Helium Instrument (EPHIN) on SOHO were used to implement the 'Relativistic Electron Alert System for Exploration (REleASE)'. The REleASE forecasting scheme was recently rewritten in the open access programming language PYTHON and will be made publicly available. As a next step, along with relativistic electrons (v > 0.9 c) provided by SOHO, near-relativistic (v <0.8 c) electron measurements from other instruments like the Electron Proton Alpha Monitor (EPAM) aboard the Advanced Composition Explorer (ACE) have been utilized. In this work, we demonstrate the real-time outputs derived by the end user from the REleASE using both SOHO/EPHIN and ACE/EPAM. We further, show a user friendly illustration of the outputs that make use of a "traffic light" to monitor the different warning stages: quiet, warning, alert offering a simple guidance to the end users. Finally, the capabilities offered by this new system, accessing both the pictorial and textural outputs REleASE are being presented. This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324.

Atomistic modelling of scattering data in the Collaborative Computational Project for Small Angle Scattering (CCP-SAS).

PubMed

Perkins, Stephen J; Wright, David W; Zhang, Hailiang; Brookes, Emre H; Chen, Jianhan; Irving, Thomas C; Krueger, Susan; Barlow, David J; Edler, Karen J; Scott, David J; Terrill, Nicholas J; King, Stephen M; Butler, Paul D; Curtis, Joseph E

2016-12-01

The capabilities of current computer simulations provide a unique opportunity to model small-angle scattering (SAS) data at the atomistic level, and to include other structural constraints ranging from molecular and atomistic energetics to crystallography, electron microscopy and NMR. This extends the capabilities of solution scattering and provides deeper insights into the physics and chemistry of the systems studied. Realizing this potential, however, requires integrating the experimental data with a new generation of modelling software. To achieve this, the CCP-SAS collaboration (http://www.ccpsas.org/) is developing open-source, high-throughput and user-friendly software for the atomistic and coarse-grained molecular modelling of scattering data. Robust state-of-the-art molecular simulation engines and molecular dynamics and Monte Carlo force fields provide constraints to the solution structure inferred from the small-angle scattering data, which incorporates the known physical chemistry of the system. The implementation of this software suite involves a tiered approach in which GenApp provides the deployment infrastructure for running applications on both standard and high-performance computing hardware, and SASSIE provides a workflow framework into which modules can be plugged to prepare structures, carry out simulations, calculate theoretical scattering data and compare results with experimental data. GenApp produces the accessible web-based front end termed SASSIE-web , and GenApp and SASSIE also make community SAS codes available. Applications are illustrated by case studies: (i) inter-domain flexibility in two- to six-domain proteins as exemplified by HIV-1 Gag, MASP and ubiquitin; (ii) the hinge conformation in human IgG2 and IgA1 antibodies; (iii) the complex formed between a hexameric protein Hfq and mRNA; and (iv) synthetic 'bottlebrush' polymers.

Colloquium paper: bioenergetics, the origins of complexity, and the ascent of man.

PubMed

Wallace, Douglas C

2010-05-11

Complex structures are generated and maintained through energy flux. Structures embody information, and biological information is stored in nucleic acids. The progressive increase in biological complexity over geologic time is thus the consequence of the information-generating power of energy flow plus the information-accumulating capacity of DNA, winnowed by natural selection. Consequently, the most important component of the biological environment is energy flow: the availability of calories and their use for growth, survival, and reproduction. Animals can exploit and adapt to available energy resources at three levels. They can evolve different anatomical forms through nuclear DNA (nDNA) mutations permitting exploitation of alternative energy reservoirs, resulting in new species. They can evolve modified bioenergetic physiologies within a species, primarily through the high mutation rate of mitochondrial DNA (mtDNA)-encoded bioenergetic genes, permitting adjustment to regional energetic environments. They can alter the epigenomic regulation of the thousands of dispersed bioenergetic genes via mitochondrially generated high-energy intermediates permitting individual accommodation to short-term environmental energetic fluctuations. Because medicine pertains to a single species, Homo sapiens, functional human variation often involves sequence changes in bioenergetic genes, most commonly mtDNA mutations, plus changes in the expression of bioenergetic genes mediated by the epigenome. Consequently, common nDNA polymorphisms in anatomical genes may represent only a fraction of the genetic variation associated with the common "complex" diseases, and the ascent of man has been the product of 3.5 billion years of information generation by energy flow, accumulated and preserved in DNA and edited by natural selection.

Density functional theory study of defects in unalloyed δ-Pu

DOE PAGES

Hernandez, S. C.; Freibert, F. J.; Wills, J. M.

2017-03-19

Using density functional theory, we explore in this paper various classical point and complex defects within the face-centered cubic unalloyed δ-plutonium matrix that are potentially induced from self-irradiation. For plutonium only defects, the most energetically stable defect is a distorted split-interstitial. Gallium, the δ-phase stabilizer, is thermodynamically stable as a substitutional defect, but becomes unstable when participating in a complex defect configuration. Finally, complex uranium defects may thermodynamically exist as uranium substitutional with neighboring plutonium interstitial and stabilization of uranium within the lattice is shown via partial density of states and charge density difference plots to be 5f hybridization betweenmore » uranium and plutonium.« less

Space Weather Studies Using Ground-based Experimental Complex in Kazakhstan

NASA Astrophysics Data System (ADS)

Kryakunova, O.; Yakovets, A.; Monstein, C.; Nikolayevskiy, N.; Zhumabayev, B.; Gordienko, G.; Andreyev, A.; Malimbayev, A.; Levin, Yu.; Salikhov, N.; Sokolova, O.; Tsepakina, I.

2015-12-01

Kazakhstan ground-based experimental complex for space weather study is situated near Almaty. Results of space environment monitoring are accessible via Internet on the web-site of the Institute of Ionosphere (http://www.ionos.kz/?q=en/node/21) in real time. There is a complex database with hourly data of cosmic ray intensity, geomagnetic field intensity, and solar radio flux at 10.7 cm and 27.8 cm wavelengths. Several studies using those data are reported. They are an estimation of speed of a coronal mass ejection, a study of large scale traveling distrubances, an analysis of geomagnetically induced currents using the geomagnetic field data, and a solar energetic proton event on 27 January 2012.

Density functional theory study of defects in unalloyed δ-Pu

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

Hernandez, S. C.; Freibert, F. J.; Wills, J. M.

Using density functional theory, we explore in this paper various classical point and complex defects within the face-centered cubic unalloyed δ-plutonium matrix that are potentially induced from self-irradiation. For plutonium only defects, the most energetically stable defect is a distorted split-interstitial. Gallium, the δ-phase stabilizer, is thermodynamically stable as a substitutional defect, but becomes unstable when participating in a complex defect configuration. Finally, complex uranium defects may thermodynamically exist as uranium substitutional with neighboring plutonium interstitial and stabilization of uranium within the lattice is shown via partial density of states and charge density difference plots to be 5f hybridization betweenmore » uranium and plutonium.« less

Modes of Interaction of Pleckstrin Homology Domains with Membranes: Toward a Computational Biochemistry of Membrane Recognition.

PubMed

Naughton, Fiona B; Kalli, Antreas C; Sansom, Mark S P

2018-02-02

Pleckstrin homology (PH) domains mediate protein-membrane interactions by binding to phosphatidylinositol phosphate (PIP) molecules. The structural and energetic basis of selective PH-PIP interactions is central to understanding many cellular processes, yet the molecular complexities of the PH-PIP interactions are largely unknown. Molecular dynamics simulations using a coarse-grained model enables estimation of free-energy landscapes for the interactions of 12 different PH domains with membranes containing PIP 2 or PIP 3 , allowing us to obtain a detailed molecular energetic understanding of the complexities of the interactions of the PH domains with PIP molecules in membranes. Distinct binding modes, corresponding to different distributions of cationic residues on the PH domain, were observed, involving PIP interactions at either the "canonical" (C) and/or "alternate" (A) sites. PH domains can be grouped by the relative strength of their C- and A-site interactions, revealing that a higher affinity correlates with increased C-site interactions. These simulations demonstrate that simultaneous binding of multiple PIP molecules by PH domains contributes to high-affinity membrane interactions, informing our understanding of membrane recognition by PH domains in vivo. Copyright © 2017. Published by Elsevier Ltd.

Atomic scale origins of sub-band gap optical absorption in gold-hyperdoped silicon

NASA Astrophysics Data System (ADS)

Ferdous, Naheed; Ertekin, Elif

2018-05-01

Gold hyperdoped silicon exhibits room temperature sub band gap optical absorption, with potential applications as infrared absorbers/detectors and impurity band photovoltaics. We use first-principles density functional theory to establish the origins of the sub band gap response. Substitutional gold AuSi and substitutional dimers AuSi - AuSi are found to be the energetically preferred defect configurations, and AuSi gives rise to partially filled mid-gap defect bands well offset from the band edges. AuSi is predicted to offer substantial sub-band gap absorption, exceeding that measured in prior experiments by two orders of magnitude for similar Au concentration. This suggests that in experimentally realized systems, in addition to AuSi, the implanted gold is accommodated by the lattice in other ways, including other defect complexes and gold precipitates. We further identify that it is energetically favorable for isolated AuSi to form AuSi - AuSi, which by contrast do not exhibit mid-gap states. The formation of dimers and other complexes could serve as nuclei in the earliest stages of Au precipitation, which may be responsible for the observed rapid deactivation of sub-band gap response upon annealing.

Stability of Glycine to Energetic Processing Under Astrophysical Conditions Investigated via Infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Maté, Belén; Herrero, Victor Jose; Tanarro, Isabel; Escribano, Rafael

2015-06-01

Glycine, the simplest aminoacid, has been detected in comets and meteorites in our Solar System. Its detection in the interstellar medium is not improbable since other organic molecules of comparable complexity have been observed. Information of how complex organic molecules resist the energetic processing that they may suffer in different regions of space is of great interest for astrochemists and astrobiologists. Further to previous investigations we have studied in this work, via infrared spectroscopy, the effect of 2 keV electron bombardment on amorphous and crystalline glycine layers at low temperatures, to determine its destruction cross section under astrophysical conditions. Energetic electrons are known to be present in the solar wind and in planetary magnetospheres, and are also formed in the interaction of cosmic rays with matter. Moreover, we have probed the shielding effect of water ice layers grown on top of the glycine samples at 90 K. These experiment aim to mimic the conditions of the aminoacid in ice mantles on dust grains in the interstellar medium or in some outer Solar System objects, with a water ice surface crust. A residual material, product of glycine decomposition, was found at the end of the processing. A tentative assignment of the infrared spectra of the residue will be discussed in the presentation. E. Herbst and E. F. van Dishoeck, Annu. Rev. Astro. Astrophys. 2009, 47:427-480 B. Maté, Y. Rodriguez-Lazcano, O. Gálvez, I. Tanarro and R. Escribano, Phys Chem Chem Phys, 2011, 13, 12268. B. Maté, I. Tanarro, M.A. Moreno, M. Jiménez-Redondo, R. Escribano, and V. J. Herrero, Faraday Discussions, 2014, DOI: 10.1039/c3fd00132f.

Methylene blue stimulates substrate-level phosphorylation catalysed by succinyl-CoA ligase in the citric acid cycle.

PubMed

Komlódi, T; Tretter, L

2017-09-01

Methylene blue (MB), a potential neuroprotective agent, is efficient in various neurodegenerative disease models. Beneficial effects of MB have been attributed to improvements in mitochondrial functions. Substrate-level phosphorylation (SLP) results in the production of ATP independent from the ATP synthase (ATP-ase). In energetically compromised mitochondria, ATP produced by SLP can prevent the reversal of the adenine nucleotide translocase and thus the hydrolysis of glycolytic ATP. The aim of the present study was to investigate the effect of MB on mitochondrial SLP catalysed by succinyl-CoA ligase. Measurements were carried out on isolated guinea pig cortical mitochondria respiring on α-ketoglutarate, glutamate, malate or succinate. The mitochondrial functions and parameters like ATP synthesis, oxygen consumption, membrane potential, and NAD(P)H level were followed online, in parallel with the redox state of MB. SLP-mediated ATP synthesis was measured in the presence of inhibitors for ATP-ase and adenylate kinase. In the presence of the ATP-ase inhibitor oligomycin MB stimulated respiration with all of the respiratory substrates. However, the rate of ATP synthesis increased only with substrates α-ketoglutarate and glutamate (forming succinyl-CoA). MB efficiently stimulated SLP and restored the membrane potential in mitochondria also with the combined inhibition of Complex I and ATP synthase. ATP formed by SLP alleviated the energetic insufficiency generated by the lack of oxidative phosphorylation. Thus, the MB-mediated stimulation of SLP might be important in maintaining the energetic competence of mitochondria and in preventing the mitochondrial hydrolysis of glycolytic ATP. The mitochondrial effects of MB are explained by the ability to accept electrons from reducing equivalents and transfer them to cytochrome c bypassing the respiratory Complexes I and III. Copyright © 2017 Elsevier Ltd. All rights reserved.

Production of complex organic molecules: H-atom addition versus UV irradiation

NASA Astrophysics Data System (ADS)

Chuang, K.-J.; Fedoseev, G.; Qasim, D.; Ioppolo, S.; van Dishoeck, E. F.; Linnartz, H.

2017-05-01

Complex organic molecules (COMs) have been identified in different environments in star-forming regions. Laboratory studies show that COMs form in the solid state, on icy grains, typically following a 'non-energetic' (atom-addition) or 'energetic' (UV-photon absorption) trigger. So far, such studies have been largely performed for single processes. Here, we present the first work that quantitatively investigates both the relative importance and the cumulative effect of '(non-)energetic' processing. We focus on astronomically relevant CO:CH3OH = 4:1 ice analogues exposed to doses relevant for the collapse stage of dense clouds. Hydrogenation experiments result in the formation of methyl formate (MF; HC(O)OCH3), glycolaldehyde (GA; HC(O)CH2OH) and ethylene glycol (EG; H2C(OH)CH2OH) at 14 K. The absolute abundances and the abundance fractions are found to be dependent on the H-atom/CO:CH3OH-molecule ratios and on the overall deposition rate. In the case that ices are exposed to UV photons only, several different COMs are found. Typically, the abundance fractions are 0.2 for MF, 0.3 for GA and 0.5 for EG as opposed to the values found in pure hydrogenation experiments without UV in which MF is largely absent: 0.0, 0.2-0.6 and 0.8-0.4, respectively. In experiments where both are applied, overall COM abundances drop to about half of those found in the pure UV irradiation experiments, but the composition fractions are very similar. This implies COM ratios can be used as a diagnostic tool to derive the processing history of an ice. Solid-state branching ratios derived here for GA and EG compare well with observations, while the MF case cannot be explained by solid-state conditions investigated here.

The Importance of Water for High Fidelity Information Processing and for Life

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.; Pohorille, Andrew

2011-01-01

Is water an absolute prerequisite for life? Life depends on a variety of non-covalent interactions among molecules, the nature of which is determined as much by the solvent in which they occur as by the molecules themselves. Catalysis and information processing, two essential functions of life, require non-covalent molecular recognition with very high specificity. For example, to correctly reproduce a string consisting of 600,000 units of information (e.g ., 600 kilobases, equivalent to the genome of the smallest free living terrestrial organisms) with a 90% success rate requires specificity > 107 : 1 for the target molecule vs. incorrect alternatives. Such specificity requires (i) that the correct molecular association is energetically stabilized by at least 40 kJ/mol relative to alternatives, and (ii) that the system is able to sample among possible states (alternative molecular associations) rapidly enough to allow the system to fall under thermodynamic control and express the energetic stabilization. We argue that electrostatic interactions are required to confer the necessary energetic stabilization vs. a large library of molecular alternatives, and that a solvent with polarity and dielectric properties comparable to water is required for the system to sample among possible states and express thermodynamic control. Electrostatic associations can be made in non-polar solvents, but the resulting complexes are too stable to be "unmade" with sufficient frequency to confer thermodynamic control on the system. An electrostatic molecular complex representing 3 units of information (e.g., 3 base pairs) with specificity > 107 per unit has a stability in non-polar solvent comparable to that of a carbon-carbon bond at room temperature. These considerations suggest that water, or a solvent with properties very like water, is necessary to support high-fidelity information processing, and can therefore be considered a critical prerequisite for life.

Recovering from "amnesia" brought about by radiation. Verification of the "Over the air" (OTA) application software update mechanism On-Board Solar Orbiter's Energetic Particle Detector

NASA Astrophysics Data System (ADS)

Da Silva, Antonio; Sánchez Prieto, Sebastián; Rodriguez Polo, Oscar; Parra Espada, Pablo

Computer memories are not supposed to forget, but they do. Because of the proximity of the Sun, from the Solar Orbiter boot software perspective, it is mandatory to look out for permanent memory errors resulting from (SEL) latch-up failures in application binaries stored in EEPROM and its SDRAM deployment areas. In this situation, the last line in defense established by FDIR mechanisms is the capability of the boot software to provide an accurate report of the memories’ damages and to perform an application software update, that avoid the harmed locations by flashing EEPROM with a new binary. This paper describes the OTA EEPROM firmware update procedure verification of the boot software that will run in the Instrument Control Unit (ICU) of the Energetic Particle Detector (EPD) on-board Solar Orbiter. Since the maximum number of rewrites on real EEPROM is limited and permanent memory faults cannot be friendly emulated in real hardware, the verification has been accomplished by the use of a LEON2 Virtual Platform (Leon2ViP) with fault injection capabilities and real SpaceWire interfaces developed by the Space Research Group (SRG) of the University of Alcalá. This way it is possible to run the exact same target binary software as if was run on the real ICU platform. Furthermore, the use of this virtual hardware-in-the-loop (VHIL) approach makes it possible to communicate with Electrical Ground Support Equipment (EGSE) through real SpaceWire interfaces in an agile, controlled and deterministic environment.

Friends with benefits: the role of huddling in mixed groups of torpid and normothermic animals.

PubMed

Nowack, Julia; Geiser, Fritz

2016-02-01

Huddling and torpor are widely used for minimizing heat loss by mammals. Despite the questionable energetic benefits from social heterothermy of mixed groups of warm normothermic and cold torpid individuals, the heterothermic Australian sugar glider (Petaurus breviceps) rests in such groups during the cold season. To unravel why they might do so, we examined torpor expression of two sugar glider groups of four individuals each in outside enclosures during winter. We observed 79 torpor bouts during 50 days of observation and found that torpor bouts were longer and deeper when all individuals of a group entered torpor together, and therefore infer that they would have saved more energy in comparison to short and shallow solitary torpor bouts. However, all gliders of either group only expressed torpor uniformly in response to food restriction, whereas on most occasions at least one individual per group remained normothermic. Nevertheless, the presence of warm gliders in mixed groups also appears to be of energetic advantage for torpid individuals, because nest box temperature was negatively correlated with the number of torpid gliders, and normothermic individuals kept the nest temperature at a value closer to the threshold for thermoregulatory heat production during torpor. Our study suggests that mixed groups of torpid and normothermic individuals are observed when environmental conditions are adverse but food is available, leading to intermediate energy savings from torpor. However, under especially challenging conditions and when animals are starving, energy savings are maximized by uniform and pronounced expression of torpor. © 2016. Published by The Company of Biologists Ltd.

Feeling labeled, judged, lectured, and rejected by family and friends over depression: cautionary results for primary care clinicians from a multi-centered, qualitative study.

PubMed

Fernandez Y-Garcia, Erik; Duberstein, Paul; Paterniti, Debora A; Cipri, Camille S; Kravitz, Richard L; Epstein, Ronald M

2012-06-29

Family and friends may help patients seek out and engage in depression care. However, patients' social networks can also undermine depression treatment and recovery. In an effort to improve depression care in primary care settings, we sought to identify, categorize, and alert primary care clinicians to depression-related messages that patients hear from friends and family that patients perceive as unhelpful or detrimental. We conducted 15 focus groups in 3 cities. Participants (n = 116) with a personal history or knowledge of depression responded to open-ended questions about depression, including self-perceived barriers to care-seeking. Focus group conversations were audio-recorded and analyzed using iterative qualitative analysis. Four themes emerged related to negatively-received depression messages delivered by family and friends. Specifically, participants perceived these messages as making them feel labeled, judged, lectured to, and rejected by family and friends when discussing depression. Some participants also expressed their interpretation of their families' motivations for delivering the messages and described how hearing these messages affected depression care. The richness of our results reflects the complexity of communication within depression sufferers' social networks around this stigmatized issue. To leverage patients' social support networks effectively in depression care, primary care clinicians should be aware of both the potentially beneficial and detrimental aspects of social support. Specifically, clinicians should consider using open-ended queries into patients' experiences with discussing depression with family and friends as an initial step in the process. An open-ended approach may avoid future emotional trauma or stigmatization and assist patients in overcoming self-imposed barriers to depression discussion, symptom disclosure, treatment adherence and follow-up care.

"That's what you do for people you love": A qualitative study of social support and recovery from a musculoskeletal injury.

PubMed

Prang, Khic-Houy; Newnam, Sharon; Berecki-Gisolf, Janneke

2018-01-01

Social support has been identified as a significant factor in facilitating better health outcomes following injury. However, research has primarily focused on the role of social support from the perspective of the person experiencing an injury. Limited research has examined the experiences of the family members and friends of a person with injury. This study aims to explore the perceptions and experiences of social support and recovery following a transport-related musculoskeletal injury (MSI) in a population of injured persons and their family members and friends. This study was conducted using a phenomenological qualitative research design. In-depth semi-structured interviews were conducted with ten persons with MSI, recruited via the Transport Accident Commission (TAC) in Victoria, Australia. Seven family members and friends were also interviewed. The data was analysed using constant comparative method and thematic analysis. Several themes were identified including: (1) key sources and types of support received, (2) relationship development and (3) challenges of providing and receiving support. Participants with MSI reported stories about how the social network provided emotional and tangible support. Family members and friends confirmed the supportive acts provided to the participants with MSI. Positive iterative changes in relationships were reported by the participants with MSI. Participants with MSI, their family members and friends described several difficulties including loss of independence, feeling like a burden, and the impact of caring on health and well-being. The role of social support is complex given the multitude of people involved in the recovery process. The findings of this study suggest that persons with MSI may benefit from support groups and maintenance of existing support networks. Furthermore, family members and friends engaged in the recovery process may benefit from support in this role.

Feeling labeled, judged, lectured, and rejected by family and friends over depression: Cautionary results for primary care clinicians from a multi-centered, qualitative study

PubMed Central

2012-01-01

Background Family and friends may help patients seek out and engage in depression care. However, patients’ social networks can also undermine depression treatment and recovery. In an effort to improve depression care in primary care settings, we sought to identify, categorize, and alert primary care clinicians to depression-related messages that patients hear from friends and family that patients perceive as unhelpful or detrimental. Methods We conducted 15 focus groups in 3 cities. Participants (n = 116) with a personal history or knowledge of depression responded to open-ended questions about depression, including self-perceived barriers to care-seeking. Focus group conversations were audio-recorded and analyzed using iterative qualitative analysis. Results Four themes emerged related to negatively-received depression messages delivered by family and friends. Specifically, participants perceived these messages as making them feel labeled, judged, lectured to, and rejected by family and friends when discussing depression. Some participants also expressed their interpretation of their families’ motivations for delivering the messages and described how hearing these messages affected depression care. Conclusions The richness of our results reflects the complexity of communication within depression sufferers’ social networks around this stigmatized issue. To leverage patients’ social support networks effectively in depression care, primary care clinicians should be aware of both the potentially beneficial and detrimental aspects of social support. Specifically, clinicians should consider using open-ended queries into patients’ experiences with discussing depression with family and friends as an initial step in the process. An open-ended approach may avoid future emotional trauma or stigmatization and assist patients in overcoming self-imposed barriers to depression discussion, symptom disclosure, treatment adherence and follow-up care. PMID:22747989

Advances in understanding the molecular basis of the first steps in color vision.

PubMed

Hofmann, Lukas; Palczewski, Krzysztof

2015-11-01

Serving as one of our primary environmental inputs, vision is the most sophisticated sensory system in humans. Here, we present recent findings derived from energetics, genetics and physiology that provide a more advanced understanding of color perception in mammals. Energetics of cis-trans isomerization of 11-cis-retinal accounts for color perception in the narrow region of the electromagnetic spectrum and how human eyes can absorb light in the near infrared (IR) range. Structural homology models of visual pigments reveal complex interactions of the protein moieties with the light sensitive chromophore 11-cis-retinal and that certain color blinding mutations impair secondary structural elements of these G protein-coupled receptors (GPCRs). Finally, we identify unsolved critical aspects of color tuning that require future investigation. Copyright © 2015. Published by Elsevier Ltd.

Nanostructure Formation by controlled dewetting on patterned substrates: A combined theoretical, modeling and experimental study

PubMed Central

Lu, Liang-Xing; Wang, Ying-Min; Srinivasan, Bharathi Madurai; Asbahi, Mohamed; Yang, Joel K. W.; Zhang, Yong-Wei

2016-01-01

We perform systematic two-dimensional energetic analysis to study the stability of various nanostructures formed by dewetting solid films deposited on patterned substrates. Our analytical results show that by controlling system parameters such as the substrate surface pattern, film thickness and wetting angle, a variety of equilibrium nanostructures can be obtained. Phase diagrams are presented to show the complex relations between these system parameters and various nanostructure morphologies. We further carry out both phase field simulations and dewetting experiments to validate the analytically derived phase diagrams. Good agreements between the results from our energetic analyses and those from our phase field simulations and experiments verify our analysis. Hence, the phase diagrams presented here provide guidelines for using solid-state dewetting as a tool to achieve various nanostructures. PMID:27580943

Simulation of loss mechanisms in organic solar cells: A description of the mesoscopic Monte Carlo technique and an evaluation of the first reaction method.

PubMed

Groves, Chris; Kimber, Robin G E; Walker, Alison B

2010-10-14

In this letter we evaluate the accuracy of the first reaction method (FRM) as commonly used to reduce the computational complexity of mesoscale Monte Carlo simulations of geminate recombination and the performance of organic photovoltaic devices. A wide range of carrier mobilities, degrees of energetic disorder, and applied electric field are considered. For the ranges of energetic disorder relevant for most polyfluorene, polythiophene, and alkoxy poly(phenylene vinylene) materials used in organic photovoltaics, the geminate separation efficiency predicted by the FRM agrees with the exact model to better than 2%. We additionally comment on the effects of equilibration on low-field geminate separation efficiency, and in doing so emphasize the importance of the energy at which geminate carriers are created upon their subsequent behavior.

Chemical releases in the ionosphere

NASA Technical Reports Server (NTRS)

Davis, T. N.

1979-01-01

The study of the interaction between the atmosphere, ionosphere and magnetosphere is identified as a major task worthy of pursuit. The present review demonstrates the major contributions to this complex problem already made by active experiments involving the injection of chemicals and energetic electron beams into the atmosphere, ionosphere and magnetosphere. Through the use of chemical releases, it has been possible to investigate a number of quantities including high-altitude winds and electric fields, the detailed configurations of the geomagnetic field within the ionosphere and the magnetosphere, as well as the propagation of energetic particle beams and their interaction with natural neutral and ionized constituents of the high atmosphere. So far, virtually all of this effort has been accomplished using rockets. In the future, it is obvious that satellite platforms will play a greater role, both in making injections and in observing their effects.

Influence of the composition of aqueous dimethylsulfoxide solvent on thermodynamics of complexing between 18-crown-6-ether and D,L-alanine

NASA Astrophysics Data System (ADS)

Usacheva, T. R.; Kuzmina, I. A.; Sharnin, V. A.; Chernov, I. V.; Matteoli, E.

2012-07-01

Standard thermodynamic parameters (log K o, Δr H o, TΔr S o) of complexing 18-crown-6 ether (18C6) with D,L-alanine (Ala) in mixed water-dimethysulfoxide (H2O-DMSO) solvents are calculated on the basis of calorimetric titration results. A rise in the DMSO concentration in mixed solvent is found to increase stability and increase the exothermicity of the formation of [Ala-18C6] molecular complex. Changes in the reaction energetic are shown to be determined by changes in the solvation state of 18C6 that is the characteristic of the reactions of molecular complex formation between 18C6 and D,L-alanine or glycine in water-organic solvents.

COMPREHENSIVE PBPK MODELING APPROACH USING THE EXPOSURE RELATED DOSE ESTIMATING MODEL (ERDEM)

EPA Science Inventory

ERDEM, a complex PBPK modeling system, is the result of the implementation of a comprehensive PBPK modeling approach. ERDEM provides a scalable and user-friendly environment that enables researchers to focus on data input values rather than writing program code. It efficiently ...

Capturing the Peer Context: The Paradox of Progress

ERIC Educational Resources Information Center

Laursen, Brett

2010-01-01

Adolescents lead enormously complicated social lives. Many youth find it difficult to keep track of their own relationships with friends and romantic interests. For the investigator, the task is exponentially more complex because overlapping and interlocking relationships and networks must be disentangled, dissected, and diagrammed. This special…

Teaching Implications: Components of a Unit on Interpersonal Communication and Aging.

ERIC Educational Resources Information Center

Webb, Lynne

One possible unit on interpersonal communication and aging consists of five components: interpersonal attraction, talk with friends and neighbors, marital communication, family communication, and personal communication with service providers. The component on interpersonal attraction explains the complex relationship of age to attraction, while…

Multi-metal oxide ceramic nanomaterial

DOEpatents

O'Brien, Stephen; Liu, Shuangyi; Huang, Limin

2016-06-07

A convenient and versatile method for preparing complex metal oxides is disclosed. The method uses a low temperature, environmentally friendly gel-collection method to form a single phase nanomaterial. In one embodiment, the nanomaterial consists of Ba.sub.AMn.sub.BTi.sub.CO.sub.D in a controlled stoichiometry.

Making Critical Friends

ERIC Educational Resources Information Center

Raven, Sara; Klein, Vanessa; Namdar, Bahadir

2016-01-01

Argumentation has long been promoted as a core scientific practice in which students should engage, yet science classrooms still often omit it. One remedy is to incorporate socioscientific issues (SSIs) in the curricula. SSIs are open-ended and complex, typically subject to multiple perspectives and solutions. These issues, influenced by science…

Sustainable Transport Systems: Linkages Between Environmental Issues, Public Transport, Non-Motorized Transport And Safety

DOT National Transportation Integrated Search

2000-10-01

A sustainable transport system must provide mobility and accessibility to all urban residents in a safe and end environmentally friendly mode of transport. This is a complex and difficult task when the needs and demands of people belonging to differe...

Food restriction increase the expression of mTORC1 complex genes in the skeletal muscle of juvenile pacu (Piaractus mesopotamicus)

PubMed Central

de Paula, Tassiana Gutierrez; Zanella, Bruna Tereza Thomazini; Fantinatti, Bruno Evaristo de Almeida; de Moraes, Leonardo Nazário; Duran, Bruno Oliveira da Silva; de Oliveira, Caroline Bredariol; Salomão, Rondinelle Artur Simões; da Silva, Rafaela Nunes; Padovani, Carlos Roberto; dos Santos, Vander Bruno; Mareco, Edson Assunção; Carvalho, Robson Francisco; Dal-Pai-Silva, Maeli

2017-01-01

Skeletal muscle is capable of phenotypic adaptation to environmental factors, such as nutrient availability, by altering the balance between muscle catabolism and anabolism that in turn coordinates muscle growth. Small noncoding RNAs, known as microRNAs (miRNAs), repress the expression of target mRNAs, and many studies have demonstrated that miRNAs regulate the mRNAs of catabolic and anabolic genes. We evaluated muscle morphology, gene expression of components involved in catabolism, anabolism and energetic metabolism and miRNAs expression in both the fast and slow muscle of juvenile pacu (Piaractus mesopotamicus) during food restriction and refeeding. Our analysis revealed that short periods of food restriction followed by refeeding predominantly affected fast muscle, with changes in muscle fiber diameter and miRNAs expression. There was an increase in the mRNA levels of catabolic pathways components (FBXO25, ATG12, BCL2) and energetic metabolism-related genes (PGC1α and SDHA), together with a decrease in PPARβ/δ mRNA levels. Interestingly, an increase in mRNA levels of anabolic genes (PI3K and mTORC1 complex: mTOR, mLST8 and RAPTOR) was also observed during food restriction. After refeeding, muscle morphology showed similar patterns of the control group; the majority of genes were slightly up- or down-regulated in fast and slow muscle, respectively; the levels of all miRNAs increased in fast muscle and some of them decreased in slow muscle. Our findings demonstrated that a short period of food restriction in juvenile pacu had a considerable impact on fast muscle, increasing the expression of anabolic (PI3K and mTORC1 complex: mTOR, mLST8 and RAPTOR) and energetic metabolism genes. The miRNAs (miR-1, miR-206, miR-199 and miR-23a) were more expressed during refeeding and while their target genes (IGF-1, mTOR, PGC1α and MAFbx), presented a decreased expression. The alterations in mTORC1 complex observed during fasting may have influenced the rates of protein synthesis by using amino acids from protein degradation as an alternative mechanism to preserve muscle phenotype and metabolic demand maintenance. PMID:28505179

The most common friend first immunization

NASA Astrophysics Data System (ADS)

Nian, Fu-Zhong; Hu, Cha-Sheng

2016-12-01

In this paper, a standard susceptible-infected-recovered-susceptible(SIRS) epidemic model based on the Watts-Strogatz (WS) small-world network model and the Barabsi-Albert (BA) scale-free network model is established, and a new immunization scheme — “the most common friend first immunization” is proposed, in which the most common friend’s node is described as being the first immune on the second layer protection of complex networks. The propagation situations of three different immunization schemes — random immunization, high-risk immunization, and the most common friend first immunization are studied. At the same time, the dynamic behaviors are also studied on the WS small-world and the BA scale-free network. Moreover, the analytic and simulated results indicate that the immune effect of the most common friend first immunization is better than random immunization, but slightly worse than high-risk immunization. However, high-risk immunization still has some limitations. For example, it is difficult to accurately define who a direct neighbor in the life is. Compared with the traditional immunization strategies having some shortcomings, the most common friend first immunization is effective, and it is nicely consistent with the actual situation. Project supported by the National Natural Science Foundation of China (Grant No. 61263019), the Program for International Science and Technology Cooperation Projects of Gansu Province, China (Grant No. 144WCGA166), and the Program for Longyuan Young Innovation Talents and the Doctoral Foundation of Lanzhou University of Technology, China.

Alkahest NuclearBLAST : a user-friendly BLAST management and analysis system

PubMed Central

Diener, Stephen E; Houfek, Thomas D; Kalat, Sam E; Windham, DE; Burke, Mark; Opperman, Charles; Dean, Ralph A

2005-01-01

Background - Sequencing of EST and BAC end datasets is no longer limited to large research groups. Drops in per-base pricing have made high throughput sequencing accessible to individual investigators. However, there are few options available which provide a free and user-friendly solution to the BLAST result storage and data mining needs of biologists. Results - Here we describe NuclearBLAST, a batch BLAST analysis, storage and management system designed for the biologist. It is a wrapper for NCBI BLAST which provides a user-friendly web interface which includes a request wizard and the ability to view and mine the results. All BLAST results are stored in a MySQL database which allows for more advanced data-mining through supplied command-line utilities or direct database access. NuclearBLAST can be installed on a single machine or clustered amongst a number of machines to improve analysis throughput. NuclearBLAST provides a platform which eases data-mining of multiple BLAST results. With the supplied scripts, the program can export data into a spreadsheet-friendly format, automatically assign Gene Ontology terms to sequences and provide bi-directional best hits between two datasets. Users with SQL experience can use the database to ask even more complex questions and extract any subset of data they require. Conclusion - This tool provides a user-friendly interface for requesting, viewing and mining of BLAST results which makes the management and data-mining of large sets of BLAST analyses tractable to biologists. PMID:15958161

Induction of complex immune responses and strong protection against retrovirus challenge by adenovirus-based immunization depends on the order of vaccine delivery.

PubMed

Kaulfuß, Meike; Wensing, Ina; Windmann, Sonja; Hrycak, Camilla Patrizia; Bayer, Wibke

2017-02-06

In the Friend retrovirus mouse model we developed potent adenovirus-based vaccines that were designed to induce either strong Friend virus GagL 85-93 -specific CD8 + T cell or antibody responses, respectively. To optimize the immunization outcome we evaluated vaccination strategies using combinations of these vaccines. While the vaccines on their own confer strong protection from a subsequent Friend virus challenge, the simple combination of the vaccines for the establishment of an optimized immunization protocol did not result in a further improvement of vaccine effectivity. We demonstrate that the co-immunization with GagL 85-93 /leader-gag encoding vectors together with envelope-encoding vectors abrogates the induction of GagL 85-93 -specific CD8 + T cells, and in successive immunization protocols the immunization with the GagL 85-93 /leader-gag encoding vector had to precede the immunization with an envelope encoding vector for the efficient induction of GagL 85-93 -specific CD8 + T cells. Importantly, the antibody response to envelope was in fact enhanced when the mice were adenovirus-experienced from a prior immunization, highlighting the expedience of this approach. To circumvent the immunosuppressive effect of envelope on immune responses to simultaneously or subsequently administered immunogens, we developed a two immunizations-based vaccination protocol that induces strong immune responses and confers robust protection of highly Friend virus-susceptible mice from a lethal Friend virus challenge.

Synthesis of a new class of carbon-bonded anionic sigma complexes with 1,3-dimethyl-2,6-dioxo-5-(2,4,6-trinitrophenyl)-1,2,3,6-tetrahydropyrimidin-4-olate moiety as insensitive high energy density materials -- implications from impact sensitivity and thermal testings.

PubMed

Kulandaiya, Rajamani; Doraisamyraja, Kalaivani

2015-01-01

Poly nitro aromatic compounds are high energy density materials. Carbon-bonded anionic sigma complexes derived from them have remarkable thermal stability. At present there is a strong requirement for thermally stable insensitive high energy density materials (IHEDMs) in the energetic field which necessitates the present investigation. Three new carbon-bonded anionic sigma complexes were synthesized from 2-chloro-1,3,5-trinitrobenzene, 1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione (1,3-dimethylbarbituric acid) and bases such as triethanolamine, pyridine and N,N-diethylaniline, characterized by UV-VIS, IR, (1)H NMR, (13)C NMR and elemental analysis data. Their molecular structures were further ascertained through single crystal X-ray diffraction studies. TGA/DTA testings were undertaken at four different heating rates (5, 10, 20 and 40 K/min) and energy of activation was determined employing Ozawa and Kissinger plots. The reported carbon-bonded anionic sigma complexes were prepared through single pot synthesis in good yield with high purity. These complexes are molecular salts comprise of cation and anion moieties. Because of the salt-like nature, they are highly stable upto 300°C and decompose in two stages on further heating. They are stable towards impact of 2 kg mass hammer upto height limit (160 cm) of the instrument. The delocalization of the negative charge and various hydrogen bonds noticed in their crystals are the added factors of their thermal stability. The new insensitive high energy density materials of the present findings may receive attention in the field of energetics in future. Graphical AbstractA new class of carbon-bonded anionic sigma complexes as insensitive high energy density materials.

VTVH-MCD and DFT studies of thiolate bonding to [FeNO]7/[FeO2]8 complexes of isopenicillin N synthase: substrate determination of oxidase versus oxygenase activity in nonheme Fe enzymes.

PubMed

Brown, Christina D; Neidig, Michael L; Neibergall, Matthew B; Lipscomb, John D; Solomon, Edward I

2007-06-13

Isopenicillin N synthase (IPNS) is a unique mononuclear nonheme Fe enzyme that catalyzes the four-electron oxidative double ring closure of its substrate ACV. A combination of spectroscopic techniques including EPR, absorbance, circular dichroism (CD), magnetic CD, and variable-temperature, variable-field MCD (VTVH-MCD) were used to evaluate the geometric and electronic structure of the [FeNO]7 complex of IPNS coordinated with the ACV thiolate ligand. Density Function Theory (DFT) calculations correlated to the spectroscopic data were used to generate an experimentally calibrated bonding description of the Fe-IPNS-ACV-NO complex. New spectroscopic features introduced by the binding of the ACV thiolate at 13 100 and 19 800 cm-1 are assigned as the NO pi*(ip) --> Fe dx2-y2 and S pi--> Fe dx2-y2 charge transfer (CT) transitions, respectively. Configuration interaction mixes S CT character into the NO pi*(ip) --> Fe dx2-y2 CT transition, which is observed experimentally from the VTVH-MCD data from this transition. Calculations on the hypothetical {FeO2}8 complex of Fe-IPNS-ACV reveal that the configuration interaction present in the [FeNO]7 complex results in an unoccupied frontier molecular orbital (FMO) with correct orientation and distal O character for H-atom abstraction from the ACV substrate. The energetics of NO/O2 binding to Fe-IPNS-ACV were evaluated and demonstrate that charge donation from the ACV thiolate ligand renders the formation of the FeIII-superoxide complex energetically favorable, driving the reaction at the Fe center. This single center reaction allows IPNS to avoid the O2 bridged binding generally invoked in other nonheme Fe enzymes that leads to oxygen insertion (i.e., oxygenase function) and determines the oxidase activity of IPNS.

A systems-based approach for integrated design of materials, products and design process chains

NASA Astrophysics Data System (ADS)

Panchal, Jitesh H.; Choi, Hae-Jin; Allen, Janet K.; McDowell, David L.; Mistree, Farrokh

2007-12-01

The concurrent design of materials and products provides designers with flexibility to achieve design objectives that were not previously accessible. However, the improved flexibility comes at a cost of increased complexity of the design process chains and the materials simulation models used for executing the design chains. Efforts to reduce the complexity generally result in increased uncertainty. We contend that a systems based approach is essential for managing both the complexity and the uncertainty in design process chains and simulation models in concurrent material and product design. Our approach is based on simplifying the design process chains systematically such that the resulting uncertainty does not significantly affect the overall system performance. Similarly, instead of striving for accurate models for multiscale systems (that are inherently complex), we rely on making design decisions that are robust to uncertainties in the models. Accordingly, we pursue hierarchical modeling in the context of design of multiscale systems. In this paper our focus is on design process chains. We present a systems based approach, premised on the assumption that complex systems can be designed efficiently by managing the complexity of design process chains. The approach relies on (a) the use of reusable interaction patterns to model design process chains, and (b) consideration of design process decisions using value-of-information based metrics. The approach is illustrated using a Multifunctional Energetic Structural Material (MESM) design example. Energetic materials store considerable energy which can be released through shock-induced detonation; conventionally, they are not engineered for strength properties. The design objectives for the MESM in this paper include both sufficient strength and energy release characteristics. The design is carried out by using models at different length and time scales that simulate different aspects of the system. Finally, by applying the method to the MESM design problem, we show that the integrated design of materials and products can be carried out more efficiently by explicitly accounting for design process decisions with the hierarchy of models.

Eco-friendly combination of the immobilized PGA enzyme and the S-Phacm protecting group for the synthesis of Cys-containing peptides.

PubMed

Góngora-Benítez, Miriam; Basso, Alessandra; Bruckdorfer, Thomas; Royo, Miriam; Tulla-Puche, Judit; Albericio, Fernando

2012-12-07

Enzyme-labile protecting groups have emerged as a green alternative to conventional protecting groups. These groups introduce a further orthogonal dimension and eco-friendliness into protection schemes for the synthesis of complex polyfunctional organic molecules. S-Phacm, a Cys-protecting group, can be easily removed by the action of a covalently immobilized PGA enzyme under very mild conditions. Herein, the versatility and reliability of an eco-friendly combination of the immobilized PGA enzyme and the S-Phacm protecting group has been evaluated for the synthesis of diverse Cys-containing peptides. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

THE OPEP COARSE-GRAINED PROTEIN MODEL: FROM SINGLE MOLECULES, AMYLOID FORMATION, ROLE OF MACROMOLECULAR CROWDING AND HYDRODYNAMICS TO RNA/DNA COMPLEXES

PubMed Central

Sterpone, Fabio; Melchionna, Simone; Tuffery, Pierre; Pasquali, Samuela; Mousseau, Normand; Cragnolini, Tristan; Chebaro, Yassmine; Saint-Pierre, Jean-Francois; Kalimeri, Maria; Barducci, Alessandro; Laurin, Yohan; Tek, Alex; Baaden, Marc; Nguyen, Phuong Hoang; Derreumaux, Philippe

2015-01-01

The OPEP coarse-grained protein model has been applied to a wide range of applications since its first release 15 years ago. The model, which combines energetic and structural accuracy and chemical specificity, allows studying single protein properties, DNA/RNA complexes, amyloid fibril formation and protein suspensions in a crowded environment. Here we first review the current state of the model and the most exciting applications using advanced conformational sampling methods. We then present the current limitations and a perspective on the on-going developments. PMID:24759934

Earth Day 2018 Activities

NASA Image and Video Library

2018-04-17

During the annual Earth Day celebration at the Kennedy Space Center Visitor Complex, guests have an opportunity to learn about the environment. The two-day event featured approximately 50 exhibitors offering information on a variety of topics, including electric vehicles, sustainable lighting, renewable energy, Florida-friendly landscaping tips, Florida’s biking trails and more.

A COMPREHENSIVE APPROACH FOR PHYSIOLOGICALLY BASED PHARMACOKINETIC (PBPK) MODELS USING THE EXPOSURE RELATED DOSE ESTIMATING MODEL (ERDEM) SYSTEM

EPA Science Inventory

The implementation of a comprehensive PBPK modeling approach resulted in ERDEM, a complex PBPK modeling system. ERDEM provides a scalable and user-friendly environment that enables researchers to focus on data input values rather than writing program code. ERDEM efficiently m...

The False-Friend Effect in Three Profoundly Deaf Learners of French: Disentangling Morphology, Phonology and Orthography

ERIC Educational Resources Information Center

Janke, Vikki; Kolokonte, Marina

2015-01-01

Three profoundly deaf individuals undertook a low-frequency backward lexical translation task (French/English), where morphological structure was manipulated and orthographic distance between test items was measured. Conditions included monomorphemic items (simplex), polymorphemic items (complex), items whose French morphological structure…

The System Dynamics Model User Sustainability Explorer (SD-MUSE): a user-friendly tool for interpreting system dynamic models

EPA Science Inventory

System Dynamics (SD) models are useful for holistic integration of data to evaluate indirect and cumulative effects and inform decisions. Complex SD models can provide key insights into how decisions affect the three interconnected pillars of sustainability. However, the complexi...

Challenges in Database Design with Microsoft Access

ERIC Educational Resources Information Center

Letkowski, Jerzy

2014-01-01

Design, development and explorations of databases are popular topics covered in introductory courses taught at business schools. Microsoft Access is the most popular software used in those courses. Despite quite high complexity of Access, it is considered to be one of the most friendly database programs for beginners. A typical Access textbook…

Order and Containment in Concurrent System Design

DTIC Science & Technology

2000-01-01

Simple. I created O.C. Jones with the help of Marshell D. Jones. iv Contents List of Figures vi List of Tables viii 1 Managing Inconsistency And Complexity...chapter. My extended family and friends provided immeasurable support. Marshell D. Jones re- minded me to take graduate school and life by the reins

True-coincidence correction when using an LEPD for the determination of the lanthanides in the environment via k0-based INAA.

PubMed

Freitas, M C; De Corte, F

1994-01-01

As part of a recent study on the environmental effects caused by the operation of a coal-fired power station at Sines, Portugal, k0-based instrumental neutron activation analysis (INAA) was used for the determination of the lanthanides (and also of tantalum and uranium) in plant leaves and lichens. In view of the accuracy and sensitivity of the determinations, it was advantageous to make use of a low-energy photon detector (LEPD). To begin with, in the present article, a survey is given of the former developments leading to user-friendly procedures for detection efficiency calibration of the LEPD and for correction for true-coincidence (cascade summing) effects. As a continuation of this, computer coincidence correction factors are now tabulated for the relevant low-energetic gamma-rays of the analytically interesting lanthanide, tantalum, and uranium radionuclides. Also the 140.5-keV line of 99Mo/99mTc is included, molybdenum being the comparator chosen when counting using an LEPD.

Modeling of the energetic ion observations in the vicinity of Rhea and Dione

NASA Astrophysics Data System (ADS)

Kotova, Anna; Roussos, Elias; Krupp, Norbert; Dandouras, Iannis

2015-09-01

During several flybys of the Cassini spacecraft by the saturnian moons Rhea and Dione the energetic particle detector MIMI/LEMMS measured a significant reduction of energetic ion fluxes (20-300 keV) in their vicinity, which is caused by the absorption of those ions at the moon surfaces. In order to simulate the observed depletion profiles we developed an energetic particle tracer, which can be used to simulate the charged particle trajectories considering different models of the saturnian magnetosphere. This particle tracer is using an adaptive fourth order Gauss Runge-Kutta calculation method and its background magnetospheric model can be varied from that of a simple dipole, to a more complex one that includes also non-dipolar perturbations. The electromagnetic environment of each local, moon-magnetosphere interaction region is modeled through a hybrid plasma simulation code. Using this energetic particle tracer we explore which of these magnetospheric characteristics are more important in shaping the MIMI/LEMMS ion profiles. We also examine if MIMI/LEMMS responds primarily to protons (as typically assumed in many studies) or also to heavier ions, using calibration information, observations of the energy flux spectrum by the MIMI/CHEMS instrument (on board of Cassini as well) and different simulation results. Our results show that MIMI/LEMMS indeed measures heavier ions as well. Also we discovered that wrapping of magnetic field lines, even if it caused local perturbations only about few percent of the background magnetic field, can cause measurable changes in the spatial and energy distribution of fluxes measured by MIMI/LEMMS. These results are important for correct interpretation of MIMI/LEMMS data, and offer capabilities for a precise in-flight instruments' cross-calibration. Besides that, our simulation approach can be employed in similar environments (Titan, Enceladus, jovian moons, etc.) for constraining the magnetic topology of their interaction region and for identifying the composition and charge-states of ions at high energies, where capabilities of the available or future instruments can be limited.

Facebook Enhances Antidepressant Pharmacotherapy Effects

PubMed Central

Mota Pereira, Jorge

2014-01-01

Treatment-resistant major depressive disorder (TR-MDD) is a complex condition, with very low remission rates. In recent years some studies have been conducted on the implementation of cognitive behavioral therapy and psychodynamic psychotherapy interventions via the Internet to MDD patients, and results have been promising. However, there have been no studies in patients with TR-MDD nor with the use of Facebook with the psychiatrist as “friend.” 60 TR-MDD patients were randomized to one of three groups: Facebook group with psychiatrist as “friend,” Facebook group without psychiatrist as “friend,” and control group (no Facebook use). Both Facebook groups spent at least 1 hour/day on Facebook, 7 days/week, during the 3 months. All patients maintained their usual pharmacotherapy. All participants were evaluated at baseline and at 1, 2, and 3 months for depressive symptoms using HAD17 and BDI-II. Results show that both Facebook groups had a decrease on HADM17 and BDI-II scores as well as higher remission and response rates than the control group, with better results if the psychiatrist was a “friend” on Facebook. Therefore, in TR-MDD, Facebook can be used as an effective enhancement therapy, adjuvant to pharmacological therapy with regular consultations, especially if the psychiatrist is the patient's online “friend.” PMID:24574930

The one number you need to grow.

PubMed

Reichheld, Frederick F

2003-12-01

Companies spend lots of time and money on complex tools to assess customer satisfaction. But they're measuring the wrong thing. The best predictor of top-line growth can usually be captured in a single survey question: Would you recommend this company to a friend? This finding is based on two years of research in which a variety of survey questions were tested by linking the responses with actual customer behavior--purchasing patterns and referrals--and ultimately with company growth. Surprisingly, the most effective question wasn't about customer satisfaction or even loyalty per se. In most of the industries studied, the percentage of customers enthusiastic enough about a company to refer it to a friend or colleague directly correlated with growth rates among competitors. Willingness to talk up a company or product to friends, family, and colleagues is one of the best indicators of loyalty because of the customer's sacrifice in making the recommendation. When customers act as references, they do more than indicate they've received good economic value from a company; they put their own reputations on the line. And they will risk their reputations only if they feel intense loyalty. The findings point to a new, simpler approach to customer research, one directly linked to a company's results. By substituting a single question--blunt tool though it may appear to be--for the complex black box of the customer satisfaction survey, companies can actually put consumer survey results to use and focus employees on the task of stimulating growth.

Binding Site and Potency Prediction of Teixobactin and other Lipid II Ligands by Statistical Base Scoring of Conformational Space Maps.

PubMed

Lungu, Claudiu N; Diudea, Mircea V

2018-01-01

Lipid II, a peptidoglycan, is a precursor in bacterial cell synthesis. It has both hydrophilic and lipophilic properties. The molecule translocates a bacterial membrane to deliver and incorporate "building blocks" from disaccharide-pentapeptide into the peptidoglican wall. Lipid II is a valid antibiotic target. A receptor binding pocket may be occupied by a ligand in various plausible conformations, among which only few ones are energetically related to a biological activity in the physiological efficiency domain. This paper reports the mapping of the conformational space of Lipid II in its interaction with Teixobactin and other Lipid II ligands. In order to study computationally the complex between Lipid II and ligands, a docking study was first carried on. Docking site was retrieved form literature. After docking, 5 ligand conformations and further 5 complexes (denoted 00 to 04) for each molecule were taken into account. For each structure, conformational studies were performed. Statistical analysis, conformational analysis and molecular dynamics based clustering were used to predict the potency of these compounds. A score for potency prediction was developed. Appling lipid II classification according to Lipid II conformational energy, a conformation of Teixobactin proved to be energetically favorable, followed by Oritravicin, Dalbavycin, Telvanicin, Teicoplamin and Vancomycin, respectively. Scoring of molecules according to cluster band and PCA produced the same result. Molecules classified according to standard deviations showed Dalbavycin as the most favorable conformation, followed by Teicoplamin, Telvanicin, Teixobactin, Oritravicin and Vancomycin, respectively. Total score showing best energetic efficiency of complex formation shows Teixobactin to have the best conformation (a score of 15 points) followed by Dalbavycin (14 points), Oritravicin (12v points), Telvanicin (10 points), Teicoplamin (9 points), Vancomycin (3 points). Statistical analysis of conformations can be used to predict the efficiency of ligand - target interaction and consecutively to find insight regarding ligand potency and postulate about favorable conformation of ligand and binding site. In this study it was shown that Teixobactin is more efficient in binding with Lipid II compared to Vancomycin, results confirmed by experimental data reported in literature. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Interfacial Interaction of Titania Nanoparticles and Ligated Uranyl Species: A Relativistic DFT Investigation.

PubMed

Zhao, Hong-Bo; Zheng, Ming; Schreckenbach, Georg; Pan, Qing-Jiang

2017-03-06

To understand interfacial behavior of actinides adsorbed onto mineral surfaces and unravel their structure-property relationship, the structures, electronic properties, and energetics of various ligated uranyl species adsorbed onto TiO 2 surface nanoparticle clusters (SNCs) were examined using relativistic density functional theory. Rutile (110) and anatase (101) titania surfaces, experimentally known to be stable, were fully optimized. For the former, models studied include clean and water-free Ti 27 O 64 H 20 (dry), partially hydrated (Ti 27 O 64 H 20 )(H 2 O) 8 (sol) and proton-saturated [(Ti 27 O 64 H 20 )(H 2 O) 8 (H) 2 ] 2+ (sat), while defect-free and defected anatase SNCs involving more than 38 TiO 2 units were considered. The aquouranyl sorption onto rutile SNCs is energetically preferred, with interaction energies of -8.54, -10.36, and -2.39 eV, respectively. Energy decomposition demonstrates that the sorption is dominated by orbital attractive interactions and modified by steric effects. Greater hydrogen-bonding involvement leads to increased orbital interactions (i.e., more negative energy) from dry to sol/sat complexes, while much larger steric interaction in the sat complex significantly reduces the sorption interaction (i.e., more positive energy). For dry SNC, adsorbates were varied from aquo to aquo-carbonato, to carbonato, to hydroxo uranyl species. Longer U-O surf /U-Ti distances and more positive sorption energies were calculated upon introducing carbonato and hydroxo ligands, indicative of weaker uranyl sorption onto the substrate. This is consistent with experimental observations that the uranyl sorption rate decreases upon raising solution pH value or adding carbon dioxide. Anatase SNCs adsorbing aquouranyl are even more exothermic, because more bonds are formed than in the case of rutile. Moreover, the anatase sorption can be tuned by surface defects as well as its Ti and O stoichiometry. All the aquouranyl-SNC complexes show similar character of molecular orbitals and energetic order although differing in highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps and orbital energy levels, but changes can be accomplished by adding carbonato and hydroxo ligands.

Development of numerical methods for overset grids with applications for the integrated Space Shuttle vehicle

NASA Technical Reports Server (NTRS)

Chan, William M.

1995-01-01

Algorithms and computer code developments were performed for the overset grid approach to solving computational fluid dynamics problems. The techniques developed are applicable to compressible Navier-Stokes flow for any general complex configurations. The computer codes developed were tested on different complex configurations with the Space Shuttle launch vehicle configuration as the primary test bed. General, efficient and user-friendly codes were produced for grid generation, flow solution and force and moment computation.

Hydrogen Bond Lifetimes and Energetics for Solute-Solvent Complexes Studied with 2D-IR Vibrational Echo Spectroscopy

PubMed Central

Zheng, Junrong; Fayer, Michael D.

2008-01-01

Weak π hydrogen bonded solute-solvent complexes are studied with ultrafast two dimensional infrared (2D-IR) vibrational echo chemical exchange spectroscopy, temperature dependent IR absorption spectroscopy, and density functional theory calculations. Eight solute-solvent complexes composed of a number of phenol derivatives and various benzene derivatives are investigated. The complexes are formed between the phenol derivative (solute) in a mixed solvent of the benzene derivative and CCl4. The time dependence of the 2D-IR vibrational echo spectra of the phenol hydroxyl stretch is used to directly determine the dissociation and formation rates of the hydrogen bonded complexes. The dissociation rates of the weak hydrogen bonds are found to be strongly correlated with their formation enthalpies. The correlation can be described with an equation similar to the Arrhenius equation. The results are discussed in terms of transition state theory. PMID:17373792

Electrical initiation of an energetic nanolaminate film

DOEpatents

Tringe, Joseph W.; Gash, Alexander E.; Barbee, Jr., Troy W.

2010-03-30

A heating apparatus comprising an energetic nanolaminate film that produces heat when initiated, a power source that provides an electric current, and a control that initiates the energetic nanolaminate film by directing the electric current to the energetic nanolaminate film and joule heating the energetic nanolaminate film to an initiation temperature. Also a method of heating comprising providing an energetic nanolaminate film that produces heat when initiated, and initiating the energetic nanolaminate film by directing an electric current to the energetic nanolaminate film and joule heating the energetic nanolaminate film to an initiation temperature.

The cystic fibrosis transmembrane recruiter the alter ego of CFTR as a multi-kinase anchor.

PubMed

Mehta, Anil

2007-11-01

This review focuses on a newly discovered interaction between protein kinases involved in cellular energetics, a process that may be disturbed in cystic fibrosis for unknown reasons. I propose a new model where kinase-mediated cellular transmission of energy provides mechanistic insight to a latent role of the cystic fibrosis transmembrane conductance regulator (CFTR). I suggest that CFTR acts as a multi-kinase recruiter to the apical epithelial membrane. My group finds that, in the cytosol, two protein kinases involved in cell energy homeostasis, nucleoside diphosphate kinase (NDPK) and AMP-activated kinase (AMPK), bind one another. Preliminary data suggest that both can also bind CFTR (function unclear). The disrupted role of this CFTR-kinase complex as 'membrane transmitter to the cell' is proposed as an alternative paradigm to the conventional ion transport mediated and CFTR/chloride-centric view of cystic fibrosis pathogenesis. Chloride remains important, but instead, chloride-induced control of the phosphohistidine content of one kinase component (NDPK, via a multi-kinase complex that also includes a third kinase, CK2; formerly casein kinase 2). I suggest that this complex provides the necessary near-equilibrium conditions needed for efficient transmission of phosphate energy to proteins controlling cellular energetics. Crucially, a new role for CFTR as a kinase controller is proposed with ionic concentration acting as a signal. The model posits a regulatory control relay for energy sensing involving a cascade of protein kinases bound to CFTR.

Structural and spectroscopic study of the europium complex with N-(diphenylphosphoryl)pyrazine-2-carboxamide

NASA Astrophysics Data System (ADS)

Pham, Y. H.; Trush, V. A.; Amirkhanov, V. M.; Gawryszewska, P.

2017-12-01

This work presents a study of the Eu3+ complex with N-(diphenylphosphoryl)pyrazine-2-carboxamide (HL) and diphenylphosphinate ions (Ph2POO-) as co-ligands with the aim of probing the specific energetic and structural characteristics that influence the ligand-to-metal energy transfer and luminescence efficiency. The compound [Eu2(L)2(μ-Ph2POO)2(κ-OP(O)Ph2)2(CH3OH)2] crystallizes as a dimer with the space group P 1 bar . Absorption and emission (295, 77 K) spectra as well as luminescence decay times were used to characterize the photophysical properties of the complex in the solid state. Very effective energy transfer from ligands to Eu3+ ion was demonstrated.

Radio data archiving system

NASA Astrophysics Data System (ADS)

Knapic, C.; Zanichelli, A.; Dovgan, E.; Nanni, M.; Stagni, M.; Righini, S.; Sponza, M.; Bedosti, F.; Orlati, A.; Smareglia, R.

2016-07-01

Radio Astronomical Data models are becoming very complex since the huge possible range of instrumental configurations available with the modern Radio Telescopes. What in the past was the last frontiers of data formats in terms of efficiency and flexibility is now evolving with new strategies and methodologies enabling the persistence of a very complex, hierarchical and multi-purpose information. Such an evolution of data models and data formats require new data archiving techniques in order to guarantee data preservation following the directives of Open Archival Information System and the International Virtual Observatory Alliance for data sharing and publication. Currently, various formats (FITS, MBFITS, VLBI's XML description files and ancillary files) of data acquired with the Medicina and Noto Radio Telescopes can be stored and handled by a common Radio Archive, that is planned to be released to the (inter)national community by the end of 2016. This state-of-the-art archiving system for radio astronomical data aims at delegating as much as possible to the software setting how and where the descriptors (metadata) are saved, while the users perform user-friendly queries translated by the web interface into complex interrogations on the database to retrieve data. In such a way, the Archive is ready to be Virtual Observatory compliant and as much as possible user-friendly.

Alterations of motor performance and brain cortex mitochondrial function during ethanol hangover.

PubMed

Bustamante, Juanita; Karadayian, Analia G; Lores-Arnaiz, Silvia; Cutrera, Rodolfo A

2012-08-01

Ethanol has been known to affect various behavioral parameters in experimental animals, even several hours after ethanol (EtOH) is absent from blood circulation, in the period known as hangover. The aim of this study was to assess the effects of acute ethanol hangover on motor performance in association with the brain cortex energetic metabolism. Evaluation of motor performance and brain cortex mitochondrial function during alcohol hangover was performed in mice 6 hours after a high ethanol dose (hangover onset). Animals were injected i.p. either with saline (control group) or with ethanol (3.8 g/kg BW) (hangover group). Ethanol hangover group showed a bad motor performance compared with control animals (p < .05). Oxygen uptake in brain cortex mitochondria from hangover animals showed a 34% decrease in the respiratory control rate as compared with the control group. Mitochondrial complex activities were decreased being the complex I-III the less affected by the hangover condition; complex II-III was markedly decreased by ethanol hangover showing 50% less activity than controls. Complex IV was 42% decreased as compared with control animals. Hydrogen peroxide production was 51% increased in brain cortex mitochondria from the hangover group, as compared with the control animals. Quantification of the mitochondrial transmembrane potential indicated that ethanol injected animals presented 17% less ability to maintain the polarized condition as compared with controls. These results indicate that a clear decrease in proton motive force occurs in brain cortex mitochondria during hangover conditions. We can conclude that a decreased motor performance observed in the hangover group of animals could be associated with brain cortex mitochondrial dysfunction and the resulting impairment of its energetic metabolism. Copyright © 2012 Elsevier Inc. All rights reserved.

Pharmacological NAD-Boosting Strategies Improve Mitochondrial Homeostasis in Human Complex I-Mutant Fibroblasts.

PubMed

Felici, Roberta; Lapucci, Andrea; Cavone, Leonardo; Pratesi, Sara; Berlinguer-Palmini, Rolando; Chiarugi, Alberto

2015-06-01

Mitochondrial disorders are devastating genetic diseases for which efficacious therapies are still an unmet need. Recent studies report that increased availability of intracellular NAD obtained by inhibition of the NAD-consuming enzyme poly(ADP-ribose) polymerase (PARP)-1 or supplementation with the NAD-precursor nicotinamide riboside (NR) ameliorates energetic derangement and symptoms in mouse models of mitochondrial disorders. Whether these pharmacological approaches also improve bioenergetics of human cells harboring mitochondrial defects is unknown. It is also unclear whether the same signaling cascade is prompted by PARP-1 inhibitors and NR supplementation to improve mitochondrial homeostasis. Here, we show that human fibroblasts mutant for the NADH dehydrogenase (ubiquinone) Fe-S protein 1 (NDUFS1) subunit of respiratory complex I have similar ATP, NAD, and mitochondrial content compared with control cells, but show reduced mitochondrial membrane potential. Interestingly, mutant cells also show increased transcript levels of mitochondrial DNA but not nuclear DNA respiratory complex subunits, suggesting activation of a compensatory response. At variance with prior work in mice, however, NR supplementation, but not PARP-1 inhibition, increased intracellular NAD content in NDUFS1 mutant human fibroblasts. Conversely, PARP-1 inhibitors, but not NR supplementation, increased transcription of mitochondrial transcription factor A and mitochondrial DNA-encoded respiratory complexes constitutively induced in mutant cells. Still, both NR and PARP-1 inhibitors restored mitochondrial membrane potential and increased organelle content as well as oxidative activity of NDUFS1-deficient fibroblasts. Overall, data provide the first evidence that in human cells harboring a mitochondrial respiratory defect exposure to NR or PARP-1, inhibitors activate different signaling pathways that are not invariantly prompted by NAD increases, but equally able to improve energetic derangement. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Fluorine-substitution induced switching of dissociation patterns of C6H4*+ produced by photoelimination of MgF2 from the complexes of mg*+ (multifluorobenzene).

PubMed

Liu, Hai-Chuan; Zhang, Xin-Hao; Wu, Yun-Dong; Yang, Shihe

2005-03-07

Complexes of fluorinated benzenes (o-C6H4-nF2+n) and Mg*+ are subjected to ultraviolet photodissociation (260-340 nm), producing efficiently benzyne radical cations (C6H4-nFn*+) besides Mg*+ and MgF+. We show that the consecutive dissociation of C6H4-nFn*+ follows the [C4(+) + C2] pattern exclusively for n < or = 2 after the parent complexes absorb one or two photons. However, the dissociation pattern is switched to [C5(+) + C1] and [C1 + C5] for n > or = 3. In particular, upon two-photon absorption at 340 nm by the complexes of Mg*+ (C6HF5) (1) and Mg*+ (C6F6) (2), photoproducts of CF+, C5H+, and C5HF*+ from C6HF3*+ and CF+, C5F+, C5F2*+, and C5F3+ from C6F4*+ are detected, respectively. Theoretical calculations are used to explain the switching of the dissociation patterns induced by the fluorine substitutions. It was found that the formation of C5+ + C1 is energetically more favorable than that of C4(+) + C2 from C6HF3*+ and C6F4*+ and of C1(+) + C5. Except for C5H2F(+) + CF, all the channels of [C5(+) + C1] and [C1(+) + C5] are energetically less favorable than those of [C4(+) + C2] from C6H3F*+ and C6H2F2*+. In most cases, the calculated results agree well with the experimental observations.

Designing interfaces of hydrogenase-nanomaterial hybrids for efficient solar conversion.

PubMed

King, Paul W

2013-01-01

The direct conversion of sunlight into biofuels is an intriguing alternative to a continued reliance on fossil fuels. Natural photosynthesis has long been investigated both as a potential solution, and as a model for utilizing solar energy to drive a water-to-fuel cycle. The molecules and organizational structure provide a template to inspire the design of efficient molecular systems for photocatalysis. A clear design strategy is the coordination of molecular interactions that match kinetic rates and energetic levels to control the direction and flow of energy from light harvesting to catalysis. Energy transduction and electron-transfer reactions occur through interfaces formed between complexes of donor-acceptor molecules. Although the structures of several of the key biological complexes have been solved, detailed descriptions of many electron-transfer complexes are lacking, which presents a challenge to designing and engineering biomolecular systems for solar conversion. Alternatively, it is possible to couple the catalytic power of biological enzymes to light harvesting by semiconductor nanomaterials. In these molecules, surface chemistry and structure can be designed using ligands. The passivation effect of the ligand can also dramatically affect the photophysical properties of the semiconductor, and energetics of external charge-transfer. The length, degree of bond saturation (aromaticity), and solvent exposed functional groups of ligands can be manipulated to further tune the interface to control molecular assembly, and complex stability in photocatalytic hybrids. The results of this research show how ligand selection is critical to designing molecular interfaces that promote efficient self-assembly, charge-transfer and photocatalysis. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems. Copyright © 2013 Elsevier B.V. All rights reserved.

Can two H2 molecules be inserted into C60 - an accurate first-principles exploration of structural, energetic and vibrational properties of the 2H2@C60 complex

NASA Astrophysics Data System (ADS)

Dolgonos, Grygoriy A.; Peslherbe, Gilles H.

2016-10-01

The 2H2@C60 minimum structure of C2 symmetry has been fully characterized at the density-fitting local second-order Møller-Plesset (DF-LMP2) level of theory. Its uncorrected and zero-point energy (ZPE) corrected complexation energies equal 1.9 and 6.2 kcal/mol, respectively, confirming the instability of the complex. This structure exhibits the largest intermolecular host-guest and guest-guest separations among all the complexes studied in this work. The calculated infrared spectrum of 2H2@C60 does not show any frequency shifts for the modes associated with radial or tangential displacements in C60 (except for one mode), but shows a weak red Hsbnd H vibrational frequency shift.

Fractality à la carte: a general particle aggregation model.

PubMed

Nicolás-Carlock, J R; Carrillo-Estrada, J L; Dossetti, V

2016-01-19

In nature, fractal structures emerge in a wide variety of systems as a local optimization of entropic and energetic distributions. The fractality of these systems determines many of their physical, chemical and/or biological properties. Thus, to comprehend the mechanisms that originate and control the fractality is highly relevant in many areas of science and technology. In studying clusters grown by aggregation phenomena, simple models have contributed to unveil some of the basic elements that give origin to fractality, however, the specific contribution from each of these elements to fractality has remained hidden in the complex dynamics. Here, we propose a simple and versatile model of particle aggregation that is, on the one hand, able to reveal the specific entropic and energetic contributions to the clusters' fractality and morphology, and, on the other, capable to generate an ample assortment of rich natural-looking aggregates with any prescribed fractal dimension.

COSTEP - Comprehensive Suprathermal and Energetic Particle Analyser

NASA Astrophysics Data System (ADS)

Müller-Mellin, R.; Kunow, H.; Fleißner, V.; Pehlke, E.; Rode, E.; Röschmann, N.; Scharmberg, C.; Sierks, H.; Rusznyak, P.; McKenna-Lawlor, S.; Elendt, I.; Sequeiros, J.; Meziat, D.; Sanchez, S.; Medina, J.; Del Peral, L.; Witte, M.; Marsden, R.; Henrion, J.

1995-12-01

The COSTEP experiment on SOHO forms part of the CEPAC complex of instruments that will perform studies of the suprathermal and energetic particle populations of solar, interplanetary, and galactic origin. Specifically, the LION and EPHIN instruments are designed to use particle emissions from the Sun for several species (electrons, protons, and helium nuclei) in the energy range 44 keV/particle to > 53 MeV/n as tools to study critical problems in solar physics as well as fundamental problems in space plasma and astrophysics. Scientific goals are presented and a technical description is provided of the two sensors and the common data processing unit. Calibration results are presented which show the ability of LION to separate electrons from protons and the ability of EPHIN to obtain energy spectra and achieve isotope separation for light nuclei. A brief description of mission operations and data products is given.

High-pressure/high-temperature polymorphs of energetic materials by first-principles simulations

NASA Astrophysics Data System (ADS)

Le, Nam; Schweigert, Igor

2017-06-01

Energetic molecular crystals exhibit complex phase diagrams that include solid-solid phase transitions, melting, and decomposition. Sorescu and Rice have recently demonstrated that first-principles molecular dynamics (MD) simulations based on dispersion-corrected density functional theory (DFT) can capture the α to γ phase transition in hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) on time scales of several picoseconds. Motivated by their work, we are using DFT-based MD to model the relative stability of solid phases in several molecular crystals. In this presentation, we report simulations of pentaerythritol tetranitrate (PETN) and 2,4,6-trinitrotoluene (TNT) under high pressures and temperatures and compare them with experimentally observed polymorphs. This work was supported by the U.S. Naval Research Laboratory via the National Research Council and by the Office of Naval Research through the U.S. Naval Research Laboratory.

Reactivity of young chars via energetic distribution measurements

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

Calo, J.M.; Lilly, W.D.

1991-01-01

The current project is directed at developing related techniques for the characterization and prediction/correlation of the reactivity of young'' chars to steam and oxygen. Of particular interest is mapping of the reactivity behavior of the resultant chars, as revealed by the energetic heterogeneity of the complexes with char preparation conditions; i.e., heating rate and ultimate temperature. In this first quarterly technical progress report we present the background of the project and the research program for the proposed investigations. The following work was accomplished on the experimental apparatus: a new set of electronics for the UTi quadrupole mass spectrometer head wasmore » purchased and delivered. The Temperature Programmed Desorption (TPD) System was moved to another laboratory and interfaced with the mass spectrometer system. A Polycold{trademark} freon refrigeration system was repaired and interfaced with the vacuum system for the TPD apparatus. It will be used to cool the diffusion pump trap. 60 refs.« less

Aerodynamic study of a stall regulated horizontal-axis wind turbine

NASA Astrophysics Data System (ADS)

Constantinescu, S. G.; Crunteanu, D. E.; Niculescu, M. L.

2013-10-01

The wind energy is deemed as one of the most durable energetic variants of the future because the wind resources are immense. Furthermore, one predicts that the small wind turbines will play a vital role in the urban environment. Unfortunately, the complexity and the price of pitch regulated small horizontal-axis wind turbines represent ones of the main obstacles to widespread the use in populated zones. Moreover, the energetic efficiency of small stall regulated wind turbines has to be high even at low and medium wind velocities because, usually the cities are not windy places. During the running stall regulated wind turbines, due to the extremely broad range of the wind velocity, the angle of attack can reach high values and some regions of the blade will show stall and post-stall behavior. This paper deals with stall and post-stall regimes because they can induce significant vibrations, fatigue and even the wind turbine failure.

Transferable Reactive Force Fields: Extensions of ReaxFF-lg to Nitromethane.

PubMed

Larentzos, James P; Rice, Betsy M

2017-03-09

Transferable ReaxFF-lg models of nitromethane that predict a variety of material properties over a wide range of thermodynamic states are obtained by screening a library of ∼6600 potentials that were previously optimized through the Multiple Objective Evolutionary Strategies (MOES) approach using a training set that included information for other energetic materials composed of carbon, hydrogen, nitrogen, and oxygen. Models that best match experimental nitromethane lattice constants at 4.2 K and 1 atm are evaluated for transferability to high-pressure states at room temperature and are shown to better predict various liquid- and solid-phase structural, thermodynamic, and transport properties as compared to the existing ReaxFF and ReaxFF-lg parametrizations. Although demonstrated for an energetic material, the library of ReaxFF-lg models is supplied to the scientific community to enable new research explorations of complex reactive phenomena in a variety of materials research applications.

Programming curvature using origami tessellations

NASA Astrophysics Data System (ADS)

Dudte, Levi H.; Vouga, Etienne; Tachi, Tomohiro; Mahadevan, L.

2016-05-01

Origami describes rules for creating folded structures from patterns on a flat sheet, but does not prescribe how patterns can be designed to fit target shapes. Here, starting from the simplest periodic origami pattern that yields one-degree-of-freedom collapsible structures--we show that scale-independent elementary geometric constructions and constrained optimization algorithms can be used to determine spatially modulated patterns that yield approximations to given surfaces of constant or varying curvature. Paper models confirm the feasibility of our calculations. We also assess the difficulty of realizing these geometric structures by quantifying the energetic barrier that separates the metastable flat and folded states. Moreover, we characterize the trade-off between the accuracy to which the pattern conforms to the target surface, and the effort associated with creating finer folds. Our approach enables the tailoring of origami patterns to drape complex surfaces independent of absolute scale, as well as the quantification of the energetic and material cost of doing so.

On the theory of nonadiabatic bridge-mediated electron transfer. Influence of structural and energetic disorder

NASA Astrophysics Data System (ADS)

Bade, L.; Petrov, E. G.; May, V.

2003-10-01

Effects of structural and energetic disorder on nonadiabatic electron transfer (ET) reactions are discussed theoretically. To account for the sequential as well as the superexchange mechanism of ET our recent approach is used presented in J. Phys. Chem. A 105, 10176 (2001). The overall charge motion is characterized by the numerical solution of rate equations for the electronic state populations and an averaging with respect to the disorder configurations. Introducing a single effective transfer rate which can be deduced from the experiment the dependence of this rate is discussed on the geometry of the ET system as well as on the disorder model. The theory is applied to donor acceptor complexes connected by oligomers of the amino acid proline. In particular, a pronounced dependence is found of the effective transfer rate on disorder with respect to the reorganization energy.

Multipoint connectivity analysis of the May 2007 solar energetic particle events

NASA Astrophysics Data System (ADS)

Chollet, E. E.; Mewaldt, R. A.; Cummings, A. C.; Gosling, J. T.; Haggerty, D. K.; Hu, Q.; Larson, D.; Lavraud, B.; Leske, R. A.; Opitz, A.; Roelof, E. C.; Russell, C. T.; Sauvaud, J.-A.

2010-12-01

In May of 2007, the STEREO Ahead and Behind spacecraft, along with the ACE spacecraft situated between the two STEREO spacecraft, observed two small solar energetic particle (SEP) events. STEREO-A and -B observed nearly identical time profiles in the 19 May event, but in the 23 May event, the protons arrived significantly earlier at STEREO-A than at STEREO-B and the time-intensity profiles were markedly different. We present SEP anisotropy, suprathermal electron pitch angle and solar wind data to demonstrate distortion in the magnetic field topology produced by the passage of multiple interplanetary coronal mass ejections on 22 and 23 May, causing the two spacecraft to magnetically connect to different points back at the Sun. This pair of events illustrates the power of multipoint observations in detailed interpretation of complex events, since only a small shift in observer location results in different magnetic field line connections and different SEP time-intensity profiles.

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

Sunden, Fanny; Peck, Ariana; Salzman, Julia

Enzymes enable life by accelerating reaction rates to biological timescales. Conventional studies have focused on identifying the residues that have a direct involvement in an enzymatic reaction, but these so-called ‘catalytic residues’ are embedded in extensive interaction networks. Although fundamental to our understanding of enzyme function, evolution, and engineering, the properties of these networks have yet to be quantitatively and systematically explored. We dissected an interaction network of five residues in the active site of Escherichia coli alkaline phosphatase. Analysis of the complex catalytic interdependence of specific residues identified three energetically independent but structurally interconnected functional units with distinct modesmore » of cooperativity. From an evolutionary perspective, this network is orders of magnitude more probable to arise than a fully cooperative network. From a functional perspective, new catalytic insights emerge. Further, such comprehensive energetic characterization will be necessary to benchmark the algorithms required to rationally engineer highly efficient enzymes.« less

Cardiac system bioenergetics: metabolic basis of the Frank-Starling law

PubMed Central

Saks, Valdur; Dzeja, Petras; Schlattner, Uwe; Vendelin, Marko; Terzic, Andre; Wallimann, Theo

2006-01-01

The fundamental principle of cardiac behaviour is described by the Frank-Starling law relating force of contraction during systole with end-diastolic volume. While both work and respiration rates increase linearly with imposed load, the basis of mechano-energetic coupling in heart muscle has remained a long-standing enigma. Here, we highlight advances made in understanding of complex cellular and molecular mechanisms that orchestrate coupling of mitochondrial oxidative phosphorylation with ATP utilization for muscle contraction. Cardiac system bioenergetics critically depends on an interrelated metabolic infrastructure regulating mitochondrial respiration and energy fluxes throughout cellular compartments. The data reviewed indicate the significance of two interrelated systems regulating mitochondrial respiration and energy fluxes in cells: (1) the creatine kinase, adenylate kinase and glycolytic pathways that communicate flux changes generated by cellular ATPases within structurally organized enzymatic modules and networks; and (2) a secondary system based on mitochondrial participation in cellular calcium cycle, which adjusts substrate oxidation and energy-transducing processes to meet increasing cellular energy demands. By conveying energetic signals to metabolic sensors, coupled phosphotransfer reactions provide a high-fidelity regulation of the excitation–contraction cycle. Such integration of energetics with calcium signalling systems provides the basis for ‘metabolic pacing’, synchronizing the cellular electrical and mechanical activities with energy supply processes. PMID:16410283

When Friendship Hurts

ERIC Educational Resources Information Center

Anthony, Michelle

2012-01-01

Despite the expansion of bully-proofing programs in recent years, many teachers feel they lack the training necessary to manage the complexities of friendship at work in the classroom and on the playground. Teachers want their students to be friends and to be kind to each other. The reality is, all children have moments in which they are unkind.…

Earth Day 2018 Activities

NASA Image and Video Library

2018-04-17

During the annual Earth Day celebration at the Kennedy Space Center Visitor Complex, guests have an opportunity to learn more about energy awareness, the environment and sustainability. The two-day event featured approximately 50 exhibitors offering information on a variety of topics, including electric vehicles, sustainable lighting, renewable energy, Florida-friendly landscaping tips, Florida’s biking trails and more.

Earth Day 2018 Activities

NASA Image and Video Library

2018-04-17

During the annual Earth Day celebration at the Kennedy Space Center Visitor Complex, guests have an opportunity to get an up-close look at experimental electric vehicles. The two-day event featured approximately 50 exhibitors offering information on a variety of topics, including electric vehicles, sustainable lighting, renewable energy, Florida-friendly landscaping tips, Florida’s biking trails and more.

Earth Day 2018 Activities

NASA Image and Video Library

2018-04-17

During the annual Earth Day celebration at the Kennedy Space Center Visitor Complex, guests have an opportunity to learn about the environment and meet Butterfly Dan” Dunwoody. The two-day event featured approximately 50 exhibitors offering information on a variety of topics, including electric vehicles, sustainable lighting, renewable energy, Florida-friendly landscaping tips, Florida’s biking trails and more.

The Culture of High Technology: Is It "Female Friendly?"

ERIC Educational Resources Information Center

Kelly, Jan Wallace

To better understand the complexity of organizational life as a cultural system whose members share particular values, attitudes, and ways of knowing, and to understand the role of women in this culture, a study was conducted using female managers at 12 high technology companies in California's "Silicon Valley." Informants were selected…

Eight Spheres of Intimacy

ERIC Educational Resources Information Center

Skyler, Jenni; Bayer, Carey Roth

2010-01-01

Intimacy can be a complex subject. However, holistic and healthy intimacy exists in many forms and can be achieved not only with a romantic other but also with one's friends, family, professional colleagues, and self. As part of lifespan development, it is ideal to build a knowledge base and skill set to comprehend the multiple facets of intimacy.…

The Complexation of the Na(super +) by 18-Crown-6 Studied via Nuclear Magnetic Resonance

ERIC Educational Resources Information Center

Peters, Steven J.; Stevenson, Cheryl D.

2004-01-01

A student friendly experiment that teaches several important concepts of modern nuclear magnetic resonance (NMR), like multinuclear capabilities, the NMR time scale, and time-averaged signals, is described along with some important concepts of thermo chemical equilibria. The mentioned experiment involves safe and inexpensive compounds, such as…

Tungsten-catalyzed asymmetric epoxidation of allylic and homoallylic alcohols with hydrogen peroxide.

PubMed

Wang, Chuan; Yamamoto, Hisashi

2014-01-29

A simple, efficient, and environmentally friendly asymmetric epoxidation of primary, secondary, tertiary allylic, and homoallylic alcohols has been accomplished. This process was promoted by a tungsten-bishydroxamic acid complex at room temperature with the use of aqueous 30% H2O2 as oxidant, yielding the products in 84-98% ee.

"Who Are Your Friends?" Complexities in Multicultural Education

ERIC Educational Resources Information Center

Epstein, Shira Eve

2010-01-01

In this paper, I explore the experiences of fourth and fifth grade students engaged in Beyond Today, an urban after school program, that aimed to enact a social reconstructionist multicultural curriculum. The program gathered White, Black, and Latino/a youth to explore issues of discrimination and social justice and develop leadership towards…

User friendly tools to target vulnerable areas at watershed scale: evaluation of the soil vulnerability and conductivity claypan indices

USDA-ARS?s Scientific Manuscript database

One finding of the Conservation Effects Assessment Program (CEAP) watershed studies was that Best Management practices (BMPs) were not always installed where most needed: in many watersheds, only a fraction of BMPs were implemented in the most vulnerable areas. While complex computer simulation mode...

Web-Based Family Life Education: Spotlight on User Experience

ERIC Educational Resources Information Center

Doty, Jennifer; Doty, Matthew; Dwrokin, Jodi

2011-01-01

Family Life Education (FLE) websites can benefit from the field of user experience, which makes technology easy to use. A heuristic evaluation of five FLE sites was performed using Neilson's heuristics, guidelines for making sites user friendly. Greater site complexity resulted in more potential user problems. Sites most frequently had problems…

The HADDOCK2.2 Web Server: User-Friendly Integrative Modeling of Biomolecular Complexes.

PubMed

van Zundert, G C P; Rodrigues, J P G L M; Trellet, M; Schmitz, C; Kastritis, P L; Karaca, E; Melquiond, A S J; van Dijk, M; de Vries, S J; Bonvin, A M J J

2016-02-22

The prediction of the quaternary structure of biomolecular macromolecules is of paramount importance for fundamental understanding of cellular processes and drug design. In the era of integrative structural biology, one way of increasing the accuracy of modeling methods used to predict the structure of biomolecular complexes is to include as much experimental or predictive information as possible in the process. This has been at the core of our information-driven docking approach HADDOCK. We present here the updated version 2.2 of the HADDOCK portal, which offers new features such as support for mixed molecule types, additional experimental restraints and improved protocols, all of this in a user-friendly interface. With well over 6000 registered users and 108,000 jobs served, an increasing fraction of which on grid resources, we hope that this timely upgrade will help the community to solve important biological questions and further advance the field. The HADDOCK2.2 Web server is freely accessible to non-profit users at http://haddock.science.uu.nl/services/HADDOCK2.2. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

KENNEDY SPACE CENTER, FLA. - Winston Scott, executive director of Florida Space Authority, speaks to attendees at a memorial service honoring the crew of Columbia. He stands in front of the Space Memorial Mirror at the KSC Visitor Complex. Feb. 1 is the one-year anniversary of the loss of the crew and orbiter Columbia in a tragic accident as the ship returned to Earth following mission STS-107. Scott is a former astronaut who flew on Columbia in 1997. Attended by many friends, co-workers and families, the memorial service was also open to the public.

NASA Image and Video Library

2004-02-01

KENNEDY SPACE CENTER, FLA. - Winston Scott, executive director of Florida Space Authority, speaks to attendees at a memorial service honoring the crew of Columbia. He stands in front of the Space Memorial Mirror at the KSC Visitor Complex. Feb. 1 is the one-year anniversary of the loss of the crew and orbiter Columbia in a tragic accident as the ship returned to Earth following mission STS-107. Scott is a former astronaut who flew on Columbia in 1997. Attended by many friends, co-workers and families, the memorial service was also open to the public.

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.

Creating Age-Friendly Health Systems - A vision for better care of older adults.

PubMed

Mate, Kedar S; Berman, Amy; Laderman, Mara; Kabcenell, Andrea; Fulmer, Terry

2018-03-01

Safe and effective care of older adults is a crucial issue given the rapid growth of the aging demographic, many of whom have complex health and social needs. At the same time, the health care delivery environment is rapidly changing, offering a new set of opportunities to improve care of older adults. We describe the background, evidence-based changes, and testing, scale-up, and spread strategy that are part of the design of the Creating Age-Friendly Health Systems initiative. The goal is to reach 20% of U.S. hospitals and health systems by 2020, with plans to reach additional hospitals and health systems in subsequent years. Copyright © 2017 Elsevier Inc. All rights reserved.

Theoretical and Experimental Study of Inclusion Complexes of β-Cyclodextrins with Chalcone and 2',4'-Dihydroxychalcone.

PubMed

Sancho, Matias I; Andujar, Sebastian; Porasso, Rodolfo D; Enriz, Ricardo D

2016-03-31

The inclusion complexes formed by chalcone and 2',4'-dihydroxychalcone with β-cyclodextrin have been studied combining experimental (phase solubility diagrams, Fourier transform infrared spectroscopy) and molecular modeling (molecular dynamics, quantum mechanics/molecular mechanics calculations) techniques. The formation constants of the complexes were determined at different temperatures, and the thermodynamic parameters of the process were obtained. The inclusion of chalcone in β-cyclodextrin is an exothermic process, while the inclusion of 2',4'-dihydroxychalcone is endothermic. Free energy profiles, derived from umbrella sampling using molecular dynamics simulations, were constructed to analyze the binding affinity and the complexation reaction at a molecular level. Hybrid QM/MM calculations were also employed to obtain a better description of the energetic and structural aspects of the complexes. The intermolecular interactions that stabilize both inclusion complexes were characterized by means of quantum atoms in molecules theory and reduce density gradient method. The calculated interactions were experimentally observed using FTIR.

Shock interactions with heterogeneous energetic materials

NASA Astrophysics Data System (ADS)

Yarrington, Cole D.; Wixom, Ryan R.; Damm, David L.

2018-03-01

The complex physical phenomenon of shock wave interaction with material heterogeneities has significant importance and nevertheless remains little understood. In many materials, the observed macroscale response to shock loading is governed by characteristics of the microstructure. Yet, the majority of computational studies aimed at predicting phenomena affected by these processes, such as the initiation and propagation of detonation waves in explosives or shock propagation in geological materials, employ continuum material and reactive burn model treatment. In an effort to highlight the grain-scale processes that underlie the observable effects in an energetic system, a grain-scale model for hexanitrostilbene (HNS) has been developed. The measured microstructures were used to produce synthetic computational representations of the pore structure, and a density functional theory molecular dynamics derived equation of state (EOS) was used for the fully dense HNS matrix. The explicit inclusion of the microstructure along with a fully dense EOS resulted in close agreement with historical shock compression experiments. More recent experiments on the dynamic reaction threshold were also reproduced by inclusion of a global kinetics model. The complete model was shown to reproduce accurately the expected response of this heterogeneous material to shock loading. Mesoscale simulations were shown to provide a clear insight into the nature of threshold behavior and are a way to understand complex physical phenomena.

Drug-binding energetics of human α-1-acid glycoprotein assessed by isothermal titration calorimetry and molecular docking simulations

PubMed Central

Huang, Johnny X.; Cooper, Matthew A.; Baker, Mark A.; Azad, Mohammad A.K.; Nation, Roger L.; Li, Jian; Velkov, Tony

2012-01-01

This study utilizes sensitive, modern isothermal titration calorimetric (ITC) methods to characterize the microscopic thermodynamic parameters that drive the binding of basic drugs to α-1-acid glycoprotein (AGP) and thereby rationalize the thermodynamic data in relation to docking models and crystallographic structures of the drug-AGP complexes. The binding of basic compounds from the tricyclic antidepressant series, together with miaserine, chlorpromazine, disopyramide and cimetidine all displayed an exothermically driven binding interaction with AGP. The impact of protonation/deprotonation events, ionic strength, temperature and the individual selectivity of the A and F1*S AGP variants on drug-binding thermodynamics were characterized. A correlation plot of the thermodynamic parameters for all of the test compounds revealed enthalpy-entropy compensation is in effect. The exothermic binding energetics of the test compounds were driven by a combination of favorable (negative) enthalpic (ΔH°) and favorable (positive) entropic (ΔS°) contributions to the Gibbs free energy (ΔG°). Collectively, the data imply that the free energies that drive drug binding to AGP and its relationship to drug-serum residency evolve from the complex interplay of enthalpic and entropic forces from interactions with explicit combinations of hydrophobic and polar side-chain sub-domains within the multi-lobed AGP ligand binding cavity. PMID:23192962

Exploring possible reaction pathways for the o-atom transfer reactions to unsaturated substrates catalyzed by a [Ni-NO2 ] ↔ [Ni-NO] redox couple using DFT methods.

PubMed

Tsipis, Athanassios C

2017-07-15

The (nitro)(N-methyldithiocarbamato)(trimethylphospane)nickel(II), [Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] complex catalyses efficiently the O-atom transfer reactions to CO and acetylene. Energetically feasible sequence of elementary steps involved in the catalytic cycle of the air oxidation of CO and acetylene are proposed promoted by the Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] ↔ Ni(NO 2 )(S 2 CNHMe)(PMe 3 ) redox couple using DFT methods both in vacuum and dichloromethane solutions. The catalytic air oxidation of HC≡CH involves formation of a five-member metallacycle intermediate, via a [3 + 2] cyclo-addition reaction of HC≡CH to the Ni-N = O moiety of the Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] complex, followed by a β H-atom migration toward the C α carbon atom of the coordinated acetylene and release of the oxidation product (ketene). The geometric and energetic reaction profile for the reversible [Ni( κN1-NO 2 )(S 2 CNHMe)(PMe 3 )] ⇌ [Ni( κO,O2-ONO)(S 2 CNHMe)(PMe 3 )] linkage isomerization has also been modeled by DFT calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Shock interactions with heterogeneous energetic materials

DOE PAGES

Yarrington, Cole D.; Wixom, Ryan R.; Damm, David L.

2018-03-14

The complex physical phenomenon of shock wave interaction with material heterogeneities has significant importance and nevertheless remains little understood. In many materials, the observed macroscale response to shock loading is governed by characteristics of the microstructure. Yet the majority of computational studies aimed at predicting phenomena affected by these processes, such as initiation and propagation of detonation waves in explosives, or shock propagation in geological materials, employ continuum material and reactive burn model treatment. In an effort to highlight the grain-scale processes that underlie the observable effects in an energetic system, a grain-scale model for hexanitrostilbene (HNS) has been developed.more » Measured microstructures were used to produce synthetic computational representations of the pore structure, and a density functional theory molecular dynamics (DFT-MD) derived equation of state (EOS) was used for the fully dense HNS matrix. The explicit inclusion of microstructure along with a fully-dense EOS resulted in close agreement with historical shock compression experiments. More recent experiments on dynamic reaction threshold were also reproduced by inclusion of a global kinetics model. The complete model was shown to reproduce accurately the expected response of this heterogeneous material to shock loading. Mesoscale simulations were shown to provide clear insight into the nature of threshold behavior, and are a way to understand complex physical phenomena.« less

Global ablation of the mitochondrial calcium uniporter increases glycolysis in cortical neurons subjected to energetic stressors.

PubMed

Nichols, Matthew; Elustondo, Pia A; Warford, Jordan; Thirumaran, Aruloli; Pavlov, Evgeny V; Robertson, George S

2017-08-01

The effects of global mitochondrial calcium (Ca 2+ ) uniporter (MCU) deficiency on hypoxic-ischemic (HI) brain injury, neuronal Ca 2+ handling, bioenergetics and hypoxic preconditioning (HPC) were examined. Forebrain mitochondria isolated from global MCU nulls displayed markedly reduced Ca 2+ uptake and Ca 2+ -induced opening of the membrane permeability transition pore. Despite evidence that these effects should be neuroprotective, global MCU nulls and wild-type (WT) mice suffered comparable HI brain damage. Energetic stress enhanced glycolysis and depressed Complex I activity in global MCU null, relative to WT, cortical neurons. HI reduced forebrain NADH levels more in global MCU nulls than WT mice suggesting that increased glycolytic consumption of NADH suppressed Complex I activity. Compared to WT neurons, pyruvate dehydrogenase (PDH) was hyper-phosphorylated in MCU nulls at several sites that lower the supply of substrates for the tricarboxylic acid cycle. Elevation of cytosolic Ca 2+ with glutamate or ionomycin decreased PDH phosphorylation in MCU null neurons suggesting the use of alternative mitochondrial Ca 2+ transport. Under basal conditions, global MCU nulls showed similar increases of Ca 2+ handling genes in the hippocampus as WT mice subjected to HPC. We propose that long-term adaptations, common to HPC, in global MCU nulls compromise resistance to HI brain injury and disrupt HPC.

Hot-spot analysis for drug discovery targeting protein-protein interactions.

PubMed

Rosell, Mireia; Fernández-Recio, Juan

2018-04-01

Protein-protein interactions are important for biological processes and pathological situations, and are attractive targets for drug discovery. However, rational drug design targeting protein-protein interactions is still highly challenging. Hot-spot residues are seen as the best option to target such interactions, but their identification requires detailed structural and energetic characterization, which is only available for a tiny fraction of protein interactions. Areas covered: In this review, the authors cover a variety of computational methods that have been reported for the energetic analysis of protein-protein interfaces in search of hot-spots, and the structural modeling of protein-protein complexes by docking. This can help to rationalize the discovery of small-molecule inhibitors of protein-protein interfaces of therapeutic interest. Computational analysis and docking can help to locate the interface, molecular dynamics can be used to find suitable cavities, and hot-spot predictions can focus the search for inhibitors of protein-protein interactions. Expert opinion: A major difficulty for applying rational drug design methods to protein-protein interactions is that in the majority of cases the complex structure is not available. Fortunately, computational docking can complement experimental data. An interesting aspect to explore in the future is the integration of these strategies for targeting PPIs with large-scale mutational analysis.

New chemical sources of energy: A theoretical study

NASA Astrophysics Data System (ADS)

Chaban, Galina

The research presented in this dissertation employs methods of quantum chemistry for the search of highly energetic chemical compounds that can have applications as possible energy sources. The areas of research include: (1) improvement of orbital optimization methods for different types of wavefunctions which leads to substantial savings of computer time and memory; (2) predicting new high energy isomers for singlet and triplet states of Nsb3F and their kinetic stability with respect to isomerisation and dissociation reactions; (3) estimation of minimum energy reaction paths for dissociation reactions of high energy isomers of Nsb2Osb2 including potential energy barriers and minimum energy crossing points between the closest singlet and triplet states; (4) investigation of thermodynamic and kinetic stability of Van der Waals complexes M-Hsb2 (M = Li, Be, B, C, Na, Mg, Al, Si) that can play an important role in improvement of energetic properties of hydrogen based rocket fuels; (5) mapping of the potential energy surface for AlHsb2 compound in the region of crossing between sp2Bsb2 and sp2Asb1 electronic states and predicting the kinetic stability of Al complex, which suggests that Al may be among the promising candidates for inclusion into solid hydrogen for the purpose of energy storage.

[Regression analysis to select native-like structures from decoys of antigen-antibody docking].

PubMed

Chen, Zhengshan; Chi, Xiangyang; Fan, Pengfei; Zhang, Guanying; Wang, Meirong; Yu, Changming; Chen, Wei

2018-06-25

Given the increasing exploitation of antibodies in different contexts such as molecular diagnostics and therapeutics, it would be beneficial to unravel properties of antigen-antibody interaction with modeling of computational protein-protein docking, especially, in the absence of a cocrystal structure. However, obtaining a native-like antigen-antibody structure remains challenging due in part to failing to reliably discriminate accurate from inaccurate structures among tens of thousands of decoys after computational docking with existing scoring function. We hypothesized that some important physicochemical and energetic features could be used to describe antigen-antibody interfaces and identify native-like antigen-antibody structure. We prepared a dataset, a subset of Protein-Protein Docking Benchmark Version 4.0, comprising 37 nonredundant 3D structures of antigen-antibody complexes, and used it to train and test multivariate logistic regression equation which took several important physicochemical and energetic features of decoys as dependent variables. Our results indicate that the ability to identify native-like structures of our method is superior to ZRANK and ZDOCK score for the subset of antigen-antibody complexes. And then, we use our method in workflow of predicting epitope of anti-Ebola glycoprotein monoclonal antibody-4G7 and identify three accurate residues in its epitope.

Affinity and specificity of serine endopeptidase-protein inhibitor interactions. Empirical free energy calculations based on X-ray crystallographic structures.

PubMed

Krystek, S; Stouch, T; Novotny, J

1993-12-05

An empirical function was used to calculate free energy change (delta G) of complex formation between the following inhibitors and enzymes: Kunitz inhibitor (BPTI) with trypsin, trypsinogen and kallikrein; turkey ovomucoid 3rd domain (OMTKY3) with alpha-chymotrypsin and the Streptomyces griseus protease B; the potato chymotrypsin inhibitor with the protease B; and the barely chymotrypsin inhibitor and eglin-c with subtilisin and thermitase. Using X-ray coordinates of the nine complexes, we estimated the contributions that hydrophobic effect, electrostatic interactions and side-chain conformational entropy make towards the stability of the complexes. The calculated delta G values showed good agreement with the experimentally measured ones, the only exception being the kallikrein/BPTI complex whose X-ray structure was solved at an exceptionally low pH. In complexes with different enzymes, the same inhibitor residues contributed identically towards complex formation (delta G(residue) Spearman rank correlation coefficient 0.7 to 1.0). The most productive enzyme-contacting residues in OMTKY3, eglin-c, and the chymotrypsin inhibitors were found in analogous positions on their respective binding loops; thus, our calculations identified a functional (energetic) motif that parallels the well-known structural similarity of the binding loops. The delta G values calculated for BPTI complexed with trypsin (-21.7 kcal) and trypsinogen (-23.4 kcal) were similar and close to the experimental delta G value of the trypsin/BPTI complex (-18.1 kcal), lending support to the suggestion that the 10(7) difference in the observed stabilities (KA) of these two complexes reflects the energetic cost of conformational changes induced in trypsinogen during the pre-equilibrium stages of complex formation. In almost all of the complexes studied, the stabilization free energy contributed by the inhibitors was larger than that donated by the enzymes. In the trypsin-BPTI complex, the calculated delta G contribution of the amino group from the BPTI residue Lys15 (9.7 kcal) was somewhat higher than that arrived at in experiments with semisynthetic inhibitor analogs (7.5 kcal). In OMTKY3, different binding loop residues are known to affect differently the binding (delta delta G) to alpha-chymotrypsin and protease B; a good qualitative agreement was found between the calculated delta G(residue) estimates and the experimental delta delta G data (correlation coefficient 0.7). Large variations were observed in local surface complementarity and related interfacial volume in the two OMTKY3 complexes (by 20 to 60% for some side-chains).(ABSTRACT TRUNCATED AT 400 WORDS)

Improving post-detonation energetics residues estimations for the Life Cycle Environmental Assessment process for munitions.

PubMed

Walsh, Michael; Gullett, Brian; Walsh, Marianne; Bigl, Matthew; Aurell, Johanna

2018-03-01

The Life Cycle Environmental Assessment (LCEA) process for military munitions tracks possible environmental impacts incurred during all phases of the life of a munition. The greatest energetics-based emphasis in the current LCEA process is on manufacturing. A review of recent LCEAs indicates that energetics deposition on ranges from detonations and disposal during training is only peripherally examined through assessment of combustion products derived from closed-chamber testing or models. These assessments rarely report any measurable energetic residues. Field-testing of munitions for energetics residues deposition has demonstrated that over 30% of some energetic compounds remain after detonation, which conflicts with the LCEA findings. A study was conducted in the open environment to determine levels of energetics residue deposition and if combustion product results can be correlated with empirical deposition results. Energetics residues deposition, post-detonation combustion products, and fine aerosolized energetics particles following open-air detonation of blocks of Composition C4 (510 g RDX/block) were quantified. The deposited residues amounted to 3.6 mg of energetic per block of C4, or less than 0.001% of the original energetics. Aerial emissions of energetics were about 7% of the amount of deposited energetics. This research indicates that aerial combustion products analysis can provide a valuable supplement to energetics deposition data in the LCEA process but is insufficient alone to account for total residual energetics. This study demonstrates a need for the environmental testing of munitions to quantify energetics residues from live-fire training. Published by Elsevier Ltd.

Energetics and Defect Interactions of Complex Oxides for Energy Applications

NASA Astrophysics Data System (ADS)

Solomon, Jonathan Michael

The goal of this dissertation is to employ computational methods to gain greater insights into the energetics and defect interactions of complex oxides that are relevant for today's energy challenges. To achieve this goal, the development of novel computational methodologies are required to handle complex systems, including systems containing nearly 650 ions and systems with tens of thousands of possible atomic configurations. The systems that are investigated in this dissertation are aliovalently doped lanthanum orthophosphate (LaPO4) due to its potential application as a proton conducting electrolyte for intermediate temperature fuel cells, and aliovalently doped uranium dioxide (UO2) due to its importance in nuclear fuel performance and disposal. First we undertake density-functional-theory (DFT) calculations on the relative energetics of pyrophosphate defects and protons in LaPO4, including their binding with divalent dopant cations. In particular, for supercell calculations with 1.85 mol% Sr doping, we investigate the dopant-binding energies for pyrophosphate defects to be 0.37 eV, which is comparable to the value of 0.34 eV calculated for proton-dopant binding energies in the same system. These results establish that dopant-defect interactions further stabilize proton incorporation, with the hydration enthalpies when the dopants are nearest and furthest from the protons and pyrophosphate defects being -1.66 eV and -1.37 eV, respectively. Even though our calculations show that dopant binding enhances the enthalpic favorability of proton incorporation, they also suggest that such binding is likely to substantially lower the kinetic rate of hydrolysis of pyrophosphate defects. We then shift our focus to solid solutions of fluorite-structured UO 2 with trivalent rare earth fission product cations (M3+=Y, La) using a combination of ionic pair potential and DFT based methods. Calculated enthalpies of formation with respect to constituent oxides show higher energetic stability for La solid solutions than for Y. Additionally, calculations performed for different atomic configurations show a preference for reduced (increased) oxygen vacancy coordination around La (Y) dopants. The current results are shown to be qualitatively consistent with related calculations and calorimetric measurements of heats of formation in other trivalent doped fluorite oxides, which show a tendency for increasing stability and increasing preference for higher oxygen coordination with increasing size of the trivalent impurity. We expand this investigation by considering a series of trivalent rare earth fission product cations, specifically, Y3+ (1.02 A, Shannon radius with eightfold coordination), Dy3+ (1.03 A), Gd 3+ (1.05 A), Eu3+ (1.07 A), Sm3+ (1.08 A), Pm3+ (1.09 A), Nd3+ (1.11 A), Pr3+ (1.13 A), Ce3+ (1.14 A) and La3+ (1.16 A). Compounds with ionic radius of the M3+ species smaller or larger than 1.09 A are found to have energetically preferred defect ordering arrangements. Systems with preferred defect ordering arrangements are suggestive of defect clustering in short range ordered solid solutions, which is expected to limit oxygen ion mobility and therefore the rate of oxidation of spent nuclear fuel. Finally, the energetics of rare earth substituted (M3+= La, Y, and Nd) UO2 solid solutions are investigated by employing a combination of calorimetric measurements and DFT based computations. The calorimetric studies are performed by Lei Zhang and Professor Alexandra Navrotsky at the University of Calfornia, Davis, as part of a joint computational/ experimental collaborative effort supported through the Materials Science of Actinides Energy Frontier Research Center. Calculated and measured formation enthalpies agree within 10 kJ/mol for stoichiometric oxygen/metal compositions. To better understand the factors governing the stability and defect binding in rare earth substituted urania solid solutions, systematic trends in the energetics are investigated based on the present results and previous computational and experimental thermochemical studies of rare earth substituted fluorite oxides. A consistent trend towards increased energetic stability with larger size mismatch between the smaller host tetravalent cation and the larger rare earth trivalent cation is found for both actinide and non-actinide fluorite oxide systems where aliovalent substitution of M cations is compensated by oxygen vacancies. However, the large exothermic oxidation enthalpy in the UO2 based systems favors compositions with higher oxygen-to-metal ratios where charge compensation occurs through the formation of uranium cations with higher oxidation states.

Site specific interaction between ZnO nanoparticles and tyrosine: A density functional theory study

NASA Astrophysics Data System (ADS)

Singh, Satvinder; Singh, Janpreet; Singh, Baljinder; Singh, Gurinder; Kaura, Aman; Tripathi, S. K.

2018-05-01

First Principles Calculations have been performed on ZnO/Tyrosine atomic complex to study site specific interaction of Tyrosine and ZnO nanoparticles. Calculated results shows that -COOH group present in Tyrosine is energetically more favorable than -NH2 group. Interactions show ionic bonding between ZnO and Tyrosine. All the calculations have been performed under the Density Functional Theory (DFT) framework. Structural and electronic properties of (ZnO)3/Tyrosine complex have been studied. Gaussian basis set approach has been adopted for the calculations. A ring type most stable (ZnO)3 atomic cluster has been modeled, analyzed and used for the calculations.

Signal Conditioning for Satellite Borne Energetic-Charged-Particle Experiments

NASA Technical Reports Server (NTRS)

Ludwig, George H.

1961-01-01

Many of the spacecraft launched thus far have carried detectors for investigating cosmic rays, solar protons, solar plasmas, and the geomagnetically trapped radiation. These detectors, which will find continued application in the future, include ion chambers; proportional, Geiger-Muller, scintillation, Cerenkov, and solid state detectors; ion collectors; and nuclear emulsions. The instrumentation required to condition the signals from these detectors prior to telemetering is steadily growing more complex in order to permit more meaningful measurements. This report describes a number of instrumentation elements typical of the present state of the art, and a present-generation three-detector system which illustrates the integration of such basic elements into a complex system.

Intermolecular interactions of trifluorohalomethanes with Lewis bases in the gas phase: an ab initio study.

PubMed

Wang, Yi-Siang; Yin, Chih-Chien; Chao, Sheng D

2014-10-07

We perform an ab initio computational study of molecular complexes with the general formula CF3X-B that involve one trifluorohalomethane CF3X (X = Cl or Br) and one of a series of Lewis bases B in the gas phase. The Lewis bases are so chosen that they provide a range of electron-donating abilities for comparison. Based on the characteristics of their electron pairs, we consider the Lewis bases with a single n-pair (NH3 and PH3), two n-pairs (H2O and H2S), two n-pairs with an unsaturated bond (H2CO and H2CS), and a single π-pair (C2H4) and two π-pairs (C2H2). The aim is to systematically investigate the influence of the electron pair characteristics and the central atom substitution effects on the geometries and energetics of the formed complexes. The counterpoise-corrected supermolecule MP2 and coupled-cluster single double with perturbative triple [CCSD(T)] levels of theory have been employed, together with a series of basis sets up to aug-cc-pVTZ. The angular and radial configurations, the binding energies, and the electrostatic potentials of the stable complexes have been compared and discussed as the Lewis base varies. For those complexes where halogen bonding plays a significant role, the calculated geometries and energetics are consistent with the σ-hole model. Upon formation of stable complexes, the C-X bond lengths shorten, while the C-X vibrational frequencies increase, thus rendering blueshifting halogen bonds. The central atom substitution usually enlarges the intermolecular bond distances while it reduces the net charge transfers, thus weakening the bond strengths. The analysis based on the σ-hole model is grossly reliable but requires suitable modifications incorporating the central atom substitution effects, in particular, when interaction components other than electrostatic contributions are involved.

Intermolecular interactions of trifluorohalomethanes with Lewis bases in the gas phase: An ab initio study

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

Wang, Yi-Siang; Yin, Chih-Chien; Chao, Sheng D., E-mail: sdchao@spring.iam.ntu.edu.tw

2014-10-07

We perform an ab initio computational study of molecular complexes with the general formula CF{sub 3}X—B that involve one trifluorohalomethane CF{sub 3}X (X = Cl or Br) and one of a series of Lewis bases B in the gas phase. The Lewis bases are so chosen that they provide a range of electron-donating abilities for comparison. Based on the characteristics of their electron pairs, we consider the Lewis bases with a single n-pair (NH{sub 3} and PH{sub 3}), two n-pairs (H{sub 2}O and H{sub 2}S), two n-pairs with an unsaturated bond (H{sub 2}CO and H{sub 2}CS), and a single π-pairmore » (C{sub 2}H{sub 4}) and two π-pairs (C{sub 2}H{sub 2}). The aim is to systematically investigate the influence of the electron pair characteristics and the central atom substitution effects on the geometries and energetics of the formed complexes. The counterpoise-corrected supermolecule MP2 and coupled-cluster single double with perturbative triple [CCSD(T)] levels of theory have been employed, together with a series of basis sets up to aug-cc-pVTZ. The angular and radial configurations, the binding energies, and the electrostatic potentials of the stable complexes have been compared and discussed as the Lewis base varies. For those complexes where halogen bonding plays a significant role, the calculated geometries and energetics are consistent with the σ-hole model. Upon formation of stable complexes, the C–X bond lengths shorten, while the C–X vibrational frequencies increase, thus rendering blueshifting halogen bonds. The central atom substitution usually enlarges the intermolecular bond distances while it reduces the net charge transfers, thus weakening the bond strengths. The analysis based on the σ-hole model is grossly reliable but requires suitable modifications incorporating the central atom substitution effects, in particular, when interaction components other than electrostatic contributions are involved.« less

A series of energetic metal pentazolate hydrates.

PubMed

Xu, Yuangang; Wang, Qian; Shen, Cheng; Lin, Qiuhan; Wang, Pengcheng; Lu, Ming

2017-09-07

Singly or doubly bonded polynitrogen compounds can decompose to dinitrogen (N 2 ) with an extremely large energy release. This makes them attractive as potential explosives or propellants, but also challenging to produce in a stable form. Polynitrogen materials containing nitrogen as the only element exist in the form of high-pressure polymeric phases, but under ambient conditions even metastability is realized only in the presence of other elements that provide stabilization. An early example is the molecule phenylpentazole, with a five-membered all-nitrogen ring, which was first reported in the 1900s and characterized in the 1950s. Salts containing the azide anion (N 3 - ) or pentazenium cation (N 5 + ) are also known, with compounds containing the pentazole anion, cyclo-N 5 - , a more recent addition. Very recently, a bulk material containing this species was reported and then used to prepare the first example of a solid-state metal-N 5 complex. Here we report the synthesis and characterization of five metal pentazolate hydrate complexes [Na(H 2 O)(N 5 )]·2H 2 O, [M(H 2 O) 4 (N 5 ) 2 ]·4H 2 O (M = Mn, Fe and Co) and [Mg(H 2 O) 6 (N 5 ) 2 ]·4H 2 O that, with the exception of the Co complex, exhibit good thermal stability with onset decomposition temperatures greater than 100 °C. For this series we find that the N 5 - ion can coordinate to the metal cation through either ionic or covalent interactions, and is stabilized through hydrogen-bonding interactions with water. Given their energetic properties and stability, pentazole-metal complexes might potentially serve as a new class of high-energy density materials or enable the development of such materials containing only nitrogen. We also anticipate that the adaptability of the N 5 - ion in terms of its bonding interactions will enable the exploration of inorganic nitrogen analogues of metallocenes and other unusual polynitrogen complexes.

A series of energetic metal pentazolate hydrates

NASA Astrophysics Data System (ADS)

Xu, Yuangang; Wang, Qian; Shen, Cheng; Lin, Qiuhan; Wang, Pengcheng; Lu, Ming

2017-09-01

Singly or doubly bonded polynitrogen compounds can decompose to dinitrogen (N2) with an extremely large energy release. This makes them attractive as potential explosives or propellants, but also challenging to produce in a stable form. Polynitrogen materials containing nitrogen as the only element exist in the form of high-pressure polymeric phases, but under ambient conditions even metastability is realized only in the presence of other elements that provide stabilization. An early example is the molecule phenylpentazole, with a five-membered all-nitrogen ring, which was first reported in the 1900s and characterized in the 1950s. Salts containing the azide anion (N3-) or pentazenium cation (N5+) are also known, with compounds containing the pentazole anion, cyclo-N5-, a more recent addition. Very recently, a bulk material containing this species was reported and then used to prepare the first example of a solid-state metal-N5 complex. Here we report the synthesis and characterization of five metal pentazolate hydrate complexes [Na(H2O)(N5)]·2H2O, [M(H2O)4(N5)2]·4H2O (M = Mn, Fe and Co) and [Mg(H2O)6(N5)2]·4H2O that, with the exception of the Co complex, exhibit good thermal stability with onset decomposition temperatures greater than 100 °C. For this series we find that the N5- ion can coordinate to the metal cation through either ionic or covalent interactions, and is stabilized through hydrogen-bonding interactions with water. Given their energetic properties and stability, pentazole-metal complexes might potentially serve as a new class of high-energy density materials or enable the development of such materials containing only nitrogen. We also anticipate that the adaptability of the N5- ion in terms of its bonding interactions will enable the exploration of inorganic nitrogen analogues of metallocenes and other unusual polynitrogen complexes.

Thermal Properties of FOX-7

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

Burnham, A K; Weese, R K; Wang, R

Much effort has been devoted to an ongoing search for more powerful, safer and environmentally friendly explosives. Since it was developed in the late 1990s, 1,1-diamino-2,2-dinitroethene (FOX-7), with lower sensitivity and comparable performance to RDX, has received increasing interest. Preliminary results on the physical and chemical characterization of FOX-7 have shown that it possesses good thermal and chemical stability. It is expected that FOX-7 will be a new important explosive ingredient in high performance, insensitive munition (IM) explosives. One of the major focuses in research on this novel energetic material is a study of its thermal properties. Oestmark et almore » have reported that DSC curves exhibit two minor endothermic peaks as well as two major exothermic peaks. Two endothermic peaks at {approx}116 and {approx}158 C suggest the presence of two solid-solid phase transitions. A third phase change below 100 C has also been reported based on a X-ray powder diffraction (XPD) study. The shapes, areas and observed temperatures of the two decomposition peaks at {approx}235 C and {approx}280 C vary with different batches and sources of the sample, and occasionally these two peaks are merged into one. The factors leading to this variation and a more complete investigation are in progress. Our laboratories have been interested in the thermal properties of energetic materials characterized by means of various thermal analysis techniques. This paper will present our results for the thermal behavior of FOX-7 including the phase changes, decomposition, kinetic analysis and the decomposition products using DSC, TG, ARC (Accelerating Rate Calorimetry), HFC (Heat Flow Calorimetry) and simultaneous TGDTA-FTIR (Fourier Transform Infrared Spectroscopy) Spectroscopy-MS (Mass) measurements.« less

III International Conference on Laser and Plasma Researches and Technologies

NASA Astrophysics Data System (ADS)

2017-12-01

A.P. Kuznetsov and S.V. Genisaretskaya III Conference on Plasma and Laser Research and Technologies took place on January 24th until January 27th, 2017 at the National Research Nuclear University "MEPhI" (NRNU MEPhI). The Conference was organized by the Institute for Laser and Plasma Technologies and was supported by the Competitiveness Program of NRNU MEPhI. The conference program consisted of nine sections: • Laser physics and its application • Plasma physics and its application • Laser, plasma and radiation technologies in industry • Physics of extreme light fields • Controlled thermonuclear fusion • Modern problems of theoretical physics • Challenges in physics of solid state, functional materials and nanosystems • Particle accelerators and radiation technologies • Modern trends of quantum metrology. The conference is based on scientific fields as follows: • Laser, plasma and radiation technologies in industry, energetic, medicine; • Photonics, quantum metrology, optical information processing; • New functional materials, metamaterials, “smart” alloys and quantum systems; • Ultrahigh optical fields, high-power lasers, Mega Science facilities; • High-temperature plasma physics, environmentally-friendly energetic based on controlled thermonuclear fusion; • Spectroscopic synchrotron, neutron, laser research methods, quantum mechanical calculation and computer modelling of condensed media and nanostructures. More than 250 specialists took part in the Conference. They represented leading Russian scientific research centers and universities (National Research Centre "Kurchatov Institute", A.M. Prokhorov General Physics Institute, P.N. Lebedev Physical Institute, Troitsk Institute for Innovation and Fusion Research, Joint Institute for Nuclear Research, Moscow Institute of Physics and Tecnology and others) and leading scientific centers and universities from Germany, France, USA, Canada, Japan. We would like to thank heartily all of the speakers, participants, organizing and program committee members for their contribution to the conference.

Ni(II)-tetrahedral complexes: Characterization, antimicrobial properties, theoretical studies and a new family of charge-transfer transitions

NASA Astrophysics Data System (ADS)

Sarı, Nurşen; Şahin, Songül Çiğdem; Öğütcü, Hatice; Dede, Yavuz; Yalcin, Soydan; Altundaş, Aliye; Doğanay, Kadir

2013-04-01

A new amine containing selenium and their five imine, (SeSchX)(X: -H, F, Cl, Br, CH3), and Ni (II) complexes, [Ni(SeSchX)(H2O)2]Cl/[Ni(SeSchCl)(H2O)Cl], were synthesized. The compounds were characterized by means of elemental analyses, 13C and 1H NMR (for imine), FT-IR, UV-Visible spectroscopy, TGA/DTA and elemental analyses. [Ni(SeSchCl)(H2O)Cl] complex from Ni(II) complexes changes color from yellow to orange in the range pH 5-7. [Ni(SeSchCl)(H2O)Cl] complex has ligand-to-metal charge-transfer (LMCT) transitions in the basic medium. Excitation characteristics and energetic of [Ni(SeSchCl)(H2O)Cl] complex, examined via TD-DFT calculations, reveals transitions of LMCT and π → π* character that matches the experimental values. [Ni(SeSchCl)(H2O)Cl] complex showed the highest antibacterial activity when compared to other complexes reported in this work.

Constructing Pairing-Friendly Elliptic Curves under Embedding Degree 1 for Securing Critical Infrastructures.

PubMed

Wang, Maocai; Dai, Guangming; Choo, Kim-Kwang Raymond; Jayaraman, Prem Prakash; Ranjan, Rajiv

2016-01-01

Information confidentiality is an essential requirement for cyber security in critical infrastructure. Identity-based cryptography, an increasingly popular branch of cryptography, is widely used to protect the information confidentiality in the critical infrastructure sector due to the ability to directly compute the user's public key based on the user's identity. However, computational requirements complicate the practical application of Identity-based cryptography. In order to improve the efficiency of identity-based cryptography, this paper presents an effective method to construct pairing-friendly elliptic curves with low hamming weight 4 under embedding degree 1. Based on the analysis of the Complex Multiplication(CM) method, the soundness of our method to calculate the characteristic of the finite field is proved. And then, three relative algorithms to construct pairing-friendly elliptic curve are put forward. 10 elliptic curves with low hamming weight 4 under 160 bits are presented to demonstrate the utility of our approach. Finally, the evaluation also indicates that it is more efficient to compute Tate pairing with our curves, than that of Bertoni et al.

Enhancement of ionization efficiency of mass spectrometric analysis from non-electrospray ionization friendly solvents with conventional and novel ionization techniques.

PubMed

Jiang, Ping; Lucy, Charles A

2015-10-15

Electrospray ionization mass spectrometry (ESI-MS) has significantly impacted the analysis of complex biological and petroleum samples. However ESI-MS has limited ionization efficiency for samples in low dielectric and low polarity solvents. Addition of a make-up solvent through a T union or electrospray solvent through continuous flow extractive desorption electrospray ionization (CF-EDESI) enable ionization of analytes in non-ESI friendly solvents. A conventional make-up solvent addition setup was used and a CF-EDESI source was built for ionization of nitrogen-containing standards in hexane or hexane/isopropanol. Factors affecting the performance of both sources have been investigated and optimized. Both the make-up solvent addition and CF-EDESI improve the ionization efficiency for heteroatom compounds in non-ESI friendly solvents. Make-up solvent addition provides higher ionization efficiency than CF-EDESI. Neither the make-up solvent addition nor the CF-EDESI eliminates ionization suppression of nitrogen-containing compounds caused by compounds of the same chemical class. Copyright © 2015 Elsevier B.V. All rights reserved.

MASH Suite: a user-friendly and versatile software interface for high-resolution mass spectrometry data interpretation and visualization.

PubMed

Guner, Huseyin; Close, Patrick L; Cai, Wenxuan; Zhang, Han; Peng, Ying; Gregorich, Zachery R; Ge, Ying

2014-03-01

The rapid advancements in mass spectrometry (MS) instrumentation, particularly in Fourier transform (FT) MS, have made the acquisition of high-resolution and high-accuracy mass measurements routine. However, the software tools for the interpretation of high-resolution MS data are underdeveloped. Although several algorithms for the automatic processing of high-resolution MS data are available, there is still an urgent need for a user-friendly interface with functions that allow users to visualize and validate the computational output. Therefore, we have developed MASH Suite, a user-friendly and versatile software interface for processing high-resolution MS data. MASH Suite contains a wide range of features that allow users to easily navigate through data analysis, visualize complex high-resolution MS data, and manually validate automatically processed results. Furthermore, it provides easy, fast, and reliable interpretation of top-down, middle-down, and bottom-up MS data. MASH Suite is convenient, easily operated, and freely available. It can greatly facilitate the comprehensive interpretation and validation of high-resolution MS data with high accuracy and reliability.

Constructing Pairing-Friendly Elliptic Curves under Embedding Degree 1 for Securing Critical Infrastructures

PubMed Central

Dai, Guangming

2016-01-01

Information confidentiality is an essential requirement for cyber security in critical infrastructure. Identity-based cryptography, an increasingly popular branch of cryptography, is widely used to protect the information confidentiality in the critical infrastructure sector due to the ability to directly compute the user’s public key based on the user’s identity. However, computational requirements complicate the practical application of Identity-based cryptography. In order to improve the efficiency of identity-based cryptography, this paper presents an effective method to construct pairing-friendly elliptic curves with low hamming weight 4 under embedding degree 1. Based on the analysis of the Complex Multiplication(CM) method, the soundness of our method to calculate the characteristic of the finite field is proved. And then, three relative algorithms to construct pairing-friendly elliptic curve are put forward. 10 elliptic curves with low hamming weight 4 under 160 bits are presented to demonstrate the utility of our approach. Finally, the evaluation also indicates that it is more efficient to compute Tate pairing with our curves, than that of Bertoni et al. PMID:27564373

Nonlocal continuum electrostatic theory predicts surprisingly small energetic penalties for charge burial in proteins.

PubMed

Bardhan, Jaydeep P

2011-09-14

We study the energetics of burying charges, ion pairs, and ionizable groups in a simple protein model using nonlocal continuum electrostatics. Our primary finding is that the nonlocal response leads to markedly reduced solvent screening, comparable to the use of application-specific protein dielectric constants. Employing the same parameters as used in other nonlocal studies, we find that for a sphere of radius 13.4 Å containing a single +1e charge, the nonlocal solvation free energy varies less than 18 kcal/mol as the charge moves from the surface to the center, whereas the difference in the local Poisson model is ∼35 kcal/mol. Because an ion pair (salt bridge) generates a comparatively more rapidly varying Coulomb potential, energetics for salt bridges are even more significantly reduced in the nonlocal model. By varying the central parameter in nonlocal theory, which is an effective length scale associated with correlations between solvent molecules, nonlocal-model energetics can be varied from the standard local results to essentially zero; however, the existence of the reduction in charge-burial penalties is quite robust to variations in the protein dielectric constant and the correlation length. Finally, as a simple exploratory test of the implications of nonlocal response, we calculate glutamate pK(a) shifts and find that using standard protein parameters (ε(protein) = 2-4), nonlocal results match local-model predictions with much higher dielectric constants. Nonlocality may, therefore, be one factor in resolving discrepancies between measured protein dielectric constants and the model parameters often used to match titration experiments. Nonlocal models may hold significant promise to deepen our understanding of macromolecular electrostatics without substantially increasing computational complexity. © 2011 American Institute of Physics

Lunar Surface Charging during Solar Energetic Particle Events

NASA Astrophysics Data System (ADS)

Halekas, Jasper S.; Delory, G. T.; Mewaldt, R. A.; Lin, R. P.; Fillingim, M. O.; Brain, D. A.; Lee, C. O.; Stubbs, T. J.; Farrell, W. M.; Hudson, M. K.

2006-09-01

The surface of the Moon, not protected by any substantial atmosphere, is directly exposed to the impact of both solar UV and solar wind plasma and energetic particles. This creates a complex lunar electrostatic environment, with the surface typically charging slightly positive in sunlight, and negative in shadow. Observations from the Apollo era and theoretical considerations strongly suggest that surface charging leads to dust electrification and transport, posing a potentially significant hazard for exploration. The most significant charging effects should occur when the Moon is exposed to high-temperature plasmas like those encountered in the terrestrial plasmasheet or in solar storms. We now present evidence for kilovolt-scale negative charging of the shadowed lunar surface during solar energetic particle (SEP) events, utilizing data from the Lunar Prospector Electron Reflectometer (LP ER). We find that SEP events are associated with the most extreme lunar surface charging observed during the LP mission - rivaled only by previously reported charging during traversals of the terrestrial plasmasheet. The largest charging event observed by LP is a 4 kV negative surface potential (as compared to typical values of V) during a SEP event in May 1998. We characterize lunar surface charging during several SEP events, and compare to energetic particle measurements from ACE, Wind, and SOHO in order to determine the relationship between SEP events and extreme lunar surface charging. Space weather events are already considered by NASA to be a significant hazard to lunar exploration, due to high-energy ionizing radiation. Our observations demonstrate that plasma interactions with the lunar surface during SEP events, causing extreme surface charging and potentially significant dust electrification and transport, represent an additional hazard associated with space weather.

Space Radiation Hazards on Human Missions to the Moon and Mars

NASA Astrophysics Data System (ADS)

Townsend, L.

2004-12-01

One of the most significant health risks for humans exploring Earth's moon and Mars is exposure to the harsh space radiation environment. Crews on these exploration missions will be exposed to a complex mixture of very energetic particles. Chronic exposures to the ever-present background galactic cosmic ray (GCR) spectrum consisting of various fluxes of all naturally - occurring chemical elements are combined with infrequent, possibly acute exposures to large fluxes of solar energetic particles, consisting of protons and heavier particles. The GCR environment is primarily a concern for stochastic effects, such as the induction of cancer, with subsequent mortality in many cases, and late deterministic effects, such as cataracts and possible damage to the central nervous system. An acute radiation syndrome response ("radiation sickness") is not possible from the GCR environment since the organ doses are well below levels of concern. Unfortunately, the actual risks of cancer induction and mortality for the very important high-energy heavy ion component of the GCR spectrum are essentially unknown. The sporadic occurrence of extremely large solar energetic particle events, usually associated with intense solar activity, is also a major concern for Lunar and Mars missions because of the possible manifestation of acute effects from the accompanying high doses of such radiations, especially acute radiation syndrome effects such as nausea, emesis, hemorrhaging or possibly even death. Large solar energetic particle events can also contribute significantly to crew risks from cancer mortality. In this presentation an overview of current estimates of critical organ doses and equivalent doses for crews of Lunar and Mars bases and on those on transits between Earth and Mars is presented. Possible methods of mitigating these radiation exposures by shielding, thereby reducing the associated health risks to crews, are also described.

Family close but friends closer: exploring social support and resilience in older spousal dementia carers.

PubMed

Donnellan, Warren J; Bennett, Kate M; Soulsby, Laura K

2017-11-01

Spousal dementia carers have unique support needs; they are likely to disengage from their existing social networks as they need to devote more time to caring as the disease progresses. Previously we showed that support resources can facilitate resilience in carers, but the relationship is complex and varies by relationship type. The current paper aims to explore social support as a key component of resilience to identify the availability, function and perceived functional aspects of support provided to older spousal dementia carers. We conducted 23 in-depth qualitative interviews with spousal carers from two carer support groups and a care home in North West England. Family and friends served a wide range of functions but were equally available to resilient and non-resilient participants. Family support was perceived as unhelpful if it created feelings of over-dependence. Participants were less likely to resist involvement of grandchildren due to their relatively narrow and low-level support functions. Friend support was perceived as most helpful when it derived from those in similar circumstances. Neighbours played a functionally unique role of crisis management. These perceptions may moderate the effect of support on resilience. Family and friend support is not always sufficient to facilitate resilience. Support functions facilitate resilience only if they are perceived to match need. Implications of these findings are discussed.

A Comprehensive Software and Database Management System for Glomerular Filtration Rate Estimation by Radionuclide Plasma Sampling and Serum Creatinine Methods.

PubMed

Jha, Ashish Kumar

2015-01-01

Glomerular filtration rate (GFR) estimation by plasma sampling method is considered as the gold standard. However, this method is not widely used because the complex technique and cumbersome calculations coupled with the lack of availability of user-friendly software. The routinely used Serum Creatinine method (SrCrM) of GFR estimation also requires the use of online calculators which cannot be used without internet access. We have developed user-friendly software "GFR estimation software" which gives the options to estimate GFR by plasma sampling method as well as SrCrM. We have used Microsoft Windows(®) as operating system and Visual Basic 6.0 as the front end and Microsoft Access(®) as database tool to develop this software. We have used Russell's formula for GFR calculation by plasma sampling method. GFR calculations using serum creatinine have been done using MIRD, Cockcroft-Gault method, Schwartz method, and Counahan-Barratt methods. The developed software is performing mathematical calculations correctly and is user-friendly. This software also enables storage and easy retrieval of the raw data, patient's information and calculated GFR for further processing and comparison. This is user-friendly software to calculate the GFR by various plasma sampling method and blood parameter. This software is also a good system for storing the raw and processed data for future analysis.

"That's what you do for people you love": A qualitative study of social support and recovery from a musculoskeletal injury

PubMed Central

Newnam, Sharon; Berecki-Gisolf, Janneke

2018-01-01

Background Social support has been identified as a significant factor in facilitating better health outcomes following injury. However, research has primarily focused on the role of social support from the perspective of the person experiencing an injury. Limited research has examined the experiences of the family members and friends of a person with injury. This study aims to explore the perceptions and experiences of social support and recovery following a transport-related musculoskeletal injury (MSI) in a population of injured persons and their family members and friends. Methods This study was conducted using a phenomenological qualitative research design. In-depth semi-structured interviews were conducted with ten persons with MSI, recruited via the Transport Accident Commission (TAC) in Victoria, Australia. Seven family members and friends were also interviewed. The data was analysed using constant comparative method and thematic analysis. Results Several themes were identified including: (1) key sources and types of support received, (2) relationship development and (3) challenges of providing and receiving support. Participants with MSI reported stories about how the social network provided emotional and tangible support. Family members and friends confirmed the supportive acts provided to the participants with MSI. Positive iterative changes in relationships were reported by the participants with MSI. Participants with MSI, their family members and friends described several difficulties including loss of independence, feeling like a burden, and the impact of caring on health and well-being. Conclusions The role of social support is complex given the multitude of people involved in the recovery process. The findings of this study suggest that persons with MSI may benefit from support groups and maintenance of existing support networks. Furthermore, family members and friends engaged in the recovery process may benefit from support in this role. PMID:29694438

Family Physicians Managing Medical Requests From Family and Friends.

PubMed

Giroldi, Esther; Freeth, Robin; Hanssen, Maurice; Muris, Jean W M; Kay, Margareth; Cals, Jochen W L

2018-01-01

Although guidelines generally state that physicians should not treat their family members or friends (nonpatients), physicians regularly receive medical requests from nonpatients. We aimed to explore junior and senior family physicians' experiences with and attitudes toward managing medical requests from nonpatients. We conducted a qualitative study with 7 focus groups with junior and senior physicians. We performed a thematic analysis during an iterative cycle of data collection and analysis. When confronted with a medical request from a nonpatient, physicians first oriented themselves to the situation: who is this person, what is he or she asking of me, and where are we? Physicians next considered the following interrelated factors: (1) nature/strength of the relationship with the nonpatient, (2) amount of trust in his/her own knowledge and skills, (3) expected consequences of making mistakes, (4) importance of work-life balance, and (5) risk of disturbing the physician-patient process. Senior physicians applied more nuanced considerations when deciding whether to respond, whereas junior physicians experienced more difficulties dealing with these requests, were less inclined to respond, and were more concerned about disturbing the existing relationship that a person had with his/her own physician. This study provides insight into the complexity that physicians face when managing medical questions and requests from nonpatients. Facilitated group discussions during which experiences are shared can help junior physicians become more confident in dealing with these complex issues as they formulate their own personal strategy regarding provision of medical advice or treatment to family and friends. © 2018 Annals of Family Medicine, Inc.

Student giving health advice to family and friends.

PubMed

Tso, Simon; Yousuf, Asim

2016-06-01

This study explored graduate-entry medical students' experiences of health-advice requests from their family and friends. This was a descriptive thematic analysis study involving a convenience sample of medical students from the University of Warwick 4-year MB ChB graduate-entry medicine programme. Each participating student attended a one-to-one semi-structured interview. Audio recordings of the interviews were transcribed verbatim and analysed thematically. Data saturation of the main themes was achieved following 14 interviews. Of the 14 students, eight (57%) were males and six (43%) were females. Students were asked to advise on a range of human and veterinary health issues. They were prepared to offer advice on health issues that they felt competent to manage: for example, first-aid scenarios that a 'reasonable layperson' or a first-aider would be able to help with. The nature of health advice given by students became increasingly complex as they progressed through their degree programme; however, they generally refrained from giving advice on complex health issues and chose to refer the individual to seek help from competent professionals instead. Previous research highlighted inappropriate advice could delay individuals seeking help from competent professionals, resulting in adverse clinical outcomes; however, we recommend that students should not be discouraged to act as good Samaritans. Instead, educators could help them to explore the professionalism and ethical issues raised by these requests, and the practical ways of handling these requests sensitively through discussion of case scenarios with acceptable and inappropriate behaviours. This study explored graduate-entry medical students' experiences of health-advice requests from their family and friends. © 2015 John Wiley & Sons Ltd.

Dynamics of ligand substitution in labile cobalt complexes resolved by ultrafast T-jump

PubMed Central

Ma, Hairong; Wan, Chaozhi; Zewail, Ahmed H.

2008-01-01

Ligand exchange of hydrated metal complexes is common in chemical and biological systems. Using the ultrafast T-jump, we examined this process, specifically the transformation of aqua cobalt (II) complexes to their fully halogenated species. The results reveal a stepwise mechanism with time scales varying from hundreds of picoseconds to nanoseconds. The dynamics are significantly faster when the structure is retained but becomes rate-limited when the octahedral-to-tetrahedral structural change bottlenecks the transformation. Evidence is presented, from bimolecular kinetics and energetics (enthalpic and entropic), for a reaction in which the ligand assists the displacement of water molecules, with the retention of the entering ligand in the activated state. The reaction time scale deviates by one to two orders of magnitude from that of ionic diffusion, suggesting the involvement of a collisional barrier between the ion and the much larger complex. PMID:18725628

Complex Quantum Network Manifolds in Dimension d > 2 are Scale-Free

NASA Astrophysics Data System (ADS)

Bianconi, Ginestra; Rahmede, Christoph

2015-09-01

In quantum gravity, several approaches have been proposed until now for the quantum description of discrete geometries. These theoretical frameworks include loop quantum gravity, causal dynamical triangulations, causal sets, quantum graphity, and energetic spin networks. Most of these approaches describe discrete spaces as homogeneous network manifolds. Here we define Complex Quantum Network Manifolds (CQNM) describing the evolution of quantum network states, and constructed from growing simplicial complexes of dimension . We show that in d = 2 CQNM are homogeneous networks while for d > 2 they are scale-free i.e. they are characterized by large inhomogeneities of degrees like most complex networks. From the self-organized evolution of CQNM quantum statistics emerge spontaneously. Here we define the generalized degrees associated with the -faces of the -dimensional CQNMs, and we show that the statistics of these generalized degrees can either follow Fermi-Dirac, Boltzmann or Bose-Einstein distributions depending on the dimension of the -faces.

Zn vacancy-donor impurity complexes in ZnO

NASA Astrophysics Data System (ADS)

Frodason, Y. K.; Johansen, K. M.; Bjørheim, T. S.; Svensson, B. G.; Alkauskas, A.

2018-03-01

Results from hybrid density functional theory calculations on the thermodynamic stability and optical properties of the Zn vacancy (VZn) complexed with common donor impurities in ZnO are reported. Complexing VZn with donors successively removes its charge-state transition levels in the band gap, starting from the most negative one. Interestingly, the presence of a donor leads only to modest shifts in the positions of the VZn charge-state transition levels, the sign and magnitude of which can be interpreted from a polaron energetics model by taking hole-donor repulsion into account. By employing a one-dimensional configuration coordinate model, luminescence lineshapes and positions were calculated. Due to the aforementioned effects, the isolated VZn gradually changes from a mainly nonradiative defect with transitions in the infrared region in n -type material, to a radiative one with broad emission in the visible range when complexed with shallow donors.

Novel bipyridinyl oxadiazole-based metal coordination complexes: High efficient and green synthesis of 3,4-dihydropyrimidin-2(1H)-ones through the Biginelli reactions

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

Wang, Jin-Hua; Zhang, E.; Tang, Gui-Mei, E-mail: meiguit@163.com

2016-09-15

Three new metal coordination complexes, namely, [Co(BPO){sub 2}(H{sub 2}O){sub 4}](BS){sub 2}(H{sub 2}O){sub 2} (1), [Co(BPO){sub 2}(H{sub 2}O){sub 4}](ABS){sub 2}(H{sub 2}O){sub 2} (2), [Co(BPO){sub 2}(H{sub 2}O){sub 4}](MBS){sub 2}(H{sub 2}O){sub 2} (3) [BPO=2,5-di(pyridin-4-yl)-1,3,4-oxadiazole, BS=benzenesulphonate, ABS=4-aminobenzenesulphonate, MBS=4-methylbenzenesulphonate] were obtained under hydrothermal conditions. Complexes 1–3 were structurally characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR and thermogravimetric analyses (TGA). All of them display a zero-dimensional motif, in which strong intermolecular hydrogen bonding interactions (O–H···O/N) and packing interactions (C–H···π and π···π) make them achieve a three-dimensional supramolecular architecture. The primary catalytic results of these three complexes show that high efficiency for the green synthesismore » of a variety of 3,4-dihydropyrimidin-2(1H)-ones was observed under solvent free conditions through Biginelli reactions. The present catalytic protocols exhibit advantages such as excellent yield, easy isolation, eco-friendly conditions, and short reaction time. - Graphical abstract: Three new metal coordination complexes with bipyridinyl-oxadiazole were obtained under hydrothermal conditions, which display a zero-dimensional motif, and show high efficiency for the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones under solvent free conditions through Biginelli reactions. The present catalytic protocols exhibit advantages such as excellent yield, easy isolation, eco-friendly conditions, and short reaction time. Display Omitted.« less

Quantification of the transferability of a designed protein specificity switch reveals extensive epistasis in molecular recognition

DOE PAGES

Melero, Cristina; Ollikainen, Noah; Harwood, Ian; ...

2014-10-13

Re-engineering protein–protein recognition is an important route to dissecting and controlling complex interaction networks. Experimental approaches have used the strategy of “second-site suppressors,” where a functional interaction is inferred between two proteins if a mutation in one protein can be compensated by a mutation in the second. Mimicking this strategy, computational design has been applied successfully to change protein recognition specificity by predicting such sets of compensatory mutations in protein–protein interfaces. To extend this approach, it would be advantageous to be able to “transplant” existing engineered and experimentally validated specificity changes to other homologous protein–protein complexes. Here, we test thismore » strategy by designing a pair of mutations that modulates peptide recognition specificity in the Syntrophin PDZ domain, confirming the designed interaction biochemically and structurally, and then transplanting the mutations into the context of five related PDZ domain–peptide complexes. We find a wide range of energetic effects of identical mutations in structurally similar positions, revealing a dramatic context dependence (epistasis) of designed mutations in homologous protein–protein interactions. To better understand the structural basis of this context dependence, we apply a structure-based computational model that recapitulates these energetic effects and we use this model to make and validate forward predictions. The context dependence of these mutations is captured by computational predictions, our results both highlight the considerable difficulties in designing protein–protein interactions and provide challenging benchmark cases for the development of improved protein modeling and design methods that accurately account for the context.« less

A Radio Study of the Seyfert Galaxy Markarian 6: Implications for Seyfert Life Cycles

NASA Astrophysics Data System (ADS)

Kharb, P.; O'Dea, C. P.; Baum, S. A.; Colbert, E. J. M.; Xu, C.

2006-11-01

We have carried out an extensive radio study with the Very Large Array on the Seyfert 1.5 galaxy Mrk 6 and imaged a spectacular radio structure in the source. The radio emission occurs on three different spatial scales: ~7.5 kpc bubbles, ~1.5 kpc bubbles lying nearly orthogonal to them, and a ~1 kpc radio jet lying orthogonal to the kiloparsec-scale bubble. To explain the complex morphology, we first consider a scenario in which the radio structures are the result of superwinds ejected by a nuclear starburst. However, recent Spitzer observations of Mrk 6 provide an upper limit to the star formation rate (SFR) of ~5.5 Msolar yr-1, an estimate much lower than the SFR of ~33 Msolar yr-1 derived assuming that the bubbles are a result of starburst winds energized by supernova explosions. Thus, a starburst alone cannot meet the energy requirements for the creation of the bubbles in Mrk 6. We then present an energetically plausible model wherein the bubbles are a result of energy deposited by the kiloparsec-scale jet as it plows into the interstellar medium. Finally, we consider a model in which the complex radio structure is a result of an episodically powered precessing jet that changes its orientation. This model is the most attractive as it can naturally explain the complex radio morphology and is consistent with the energetics, the spectral index, and the polarization structure. Radio emission in this scenario is a short-lived phenomenon in the lifetime of a Seyfert galaxy, which results from an accretion event.

Quantification of the transferability of a designed protein specificity switch reveals extensive epistasis in molecular recognition

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

Melero, Cristina; Ollikainen, Noah; Harwood, Ian

Re-engineering protein–protein recognition is an important route to dissecting and controlling complex interaction networks. Experimental approaches have used the strategy of “second-site suppressors,” where a functional interaction is inferred between two proteins if a mutation in one protein can be compensated by a mutation in the second. Mimicking this strategy, computational design has been applied successfully to change protein recognition specificity by predicting such sets of compensatory mutations in protein–protein interfaces. To extend this approach, it would be advantageous to be able to “transplant” existing engineered and experimentally validated specificity changes to other homologous protein–protein complexes. Here, we test thismore » strategy by designing a pair of mutations that modulates peptide recognition specificity in the Syntrophin PDZ domain, confirming the designed interaction biochemically and structurally, and then transplanting the mutations into the context of five related PDZ domain–peptide complexes. We find a wide range of energetic effects of identical mutations in structurally similar positions, revealing a dramatic context dependence (epistasis) of designed mutations in homologous protein–protein interactions. To better understand the structural basis of this context dependence, we apply a structure-based computational model that recapitulates these energetic effects and we use this model to make and validate forward predictions. The context dependence of these mutations is captured by computational predictions, our results both highlight the considerable difficulties in designing protein–protein interactions and provide challenging benchmark cases for the development of improved protein modeling and design methods that accurately account for the context.« less

Heteronormativity in the University Classroom: Novelty Attachment and Content Substitution among Gay-Friendly Students

ERIC Educational Resources Information Center

Ripley, Matthew; Anderson, Eric; McCormack, Mark; Rockett, Ben

2012-01-01

This article explores the complex relationship between an openly gay instructor, homophobia, and heteronormativity in a university classroom. The authors first tabulated the frequency with which the instructor used the lives of heterosexuals and homosexuals as examples of content or as content itself, and then they interviewed 32 students about…

A Search Past Silence: The Literacy of Young Black Men. Language & Literacy

ERIC Educational Resources Information Center

Kirkland, David E.

2013-01-01

This beautifully written book argues that educators need to understand the social worlds and complex literacy practices of African-American males in order to pay the increasing educational debt we owe all youth and break the school-to-prison pipeline. Moving portraits from the lives of six friends bring to life the structural characteristics and…

How Many "Friends" Do You Need? Teaching Students How to Network Using Social Media

ERIC Educational Resources Information Center

Sacks, Michael Alan; Graves, Nikki

2012-01-01

Student reliance on social media is undeniable. However, while we largely regard social media as a new phenomena, the concepts underlying it come directly from social network theory in sociology and organizational behavior. In this article, the authors examine how the social network concepts of size, quality, complexity, diffusion, and distance…

Defense Systems Modernization and Sustainment Initiative

DTIC Science & Technology

2014-03-31

research programs focus on sustainable production, sustainable energy, sustainable mobility , and ecologically friendly information technology systems...for Sustainable Mobility (CSM): focused on developing viable technologies for sustainable transportation systems and the support of complex equipment...utilization of mobile devices. The objective of the evaluation was to identify features that the new implementation of LEEDS would require, such as

Sneaking out after Dark: Resistance, Agency, and the Postmodern Child in JK Rowling's Harry Potter Series

ERIC Educational Resources Information Center

Chappell, Drew

2008-01-01

JK Rowling's "Harry Potter" novels situate their child protagonists in a fantastical world side by side with present day British society. Through the characters' choices and realizations, young readers are introduced to the complexities and ambiguities of the contemporary world. Harry and his friends embrace these qualities of postmodern…

Using a Film to Challenge Heteronormativity: South African Teachers "Get Real" in Working with LGB Youth

ERIC Educational Resources Information Center

Richardson, Eric M.

2008-01-01

The author explains how the film "Get Real" enabled him to explore, with a group of South African student teachers, the complex ways in which queer adolescents negotiate their daily lives, the struggles they have with "coming out" to their friends and families, the problems with representation, and the connections between…

Camp Verde Adult Reading Program. Final Performance Report.

ERIC Educational Resources Information Center

Maynard, David A.

This document begins with a four-page performance report describing how the Camp Verde Adult Reading Program site was relocated to the Community Center Complex, and the Town Council contracted directly with the Friends of the Camp Verde Library to provide for the requirements of the program. The U.S. Department of Education grant allowed the…

Developing a Software for Fuzzy Group Decision Support System: A Case Study

ERIC Educational Resources Information Center

Baba, A. Fevzi; Kuscu, Dincer; Han, Kerem

2009-01-01

The complex nature and uncertain information in social problems required the emergence of fuzzy decision support systems in social areas. In this paper, we developed user-friendly Fuzzy Group Decision Support Systems (FGDSS) software. The software can be used for multi-purpose decision making processes. It helps the users determine the main and…

White Skin, Black Friend: A Fanonian Application to Theorize Racial Fetish in Teacher Education

ERIC Educational Resources Information Center

Matias, Cheryl E.

2016-01-01

In "Black Skin, white masks" (1967, Grove Press), Franz Fanon uses a psychoanalytic framework to theorize the inferiority-dependency complex of Black men in response to the colonial racism of white men. Applying his framework in reverse, this theoretical article psychoanalyzes the white psyche and emotionality with respect to the…

The North Carolina State University Libraries Search Experience: Usability Testing Tabbed Search Interfaces for Academic Libraries

ERIC Educational Resources Information Center

Teague-Rector, Susan; Ballard, Angela; Pauley, Susan K.

2011-01-01

Creating a learnable, effective, and user-friendly library Web site hinges on providing easy access to search. Designing a search interface for academic libraries can be particularly challenging given the complexity and range of searchable library collections, such as bibliographic databases, electronic journals, and article search silos. Library…

Three Applications of Automated Test Assembly within a User-Friendly Modeling Environment

ERIC Educational Resources Information Center

Cor, Ken; Alves, Cecilia; Gierl, Mark

2009-01-01

While linear programming is a common tool in business and industry, there have not been many applications in educational assessment and only a handful of individuals have been actively involved in conducting psychometric research in this area. Perhaps this is due, at least in part, to the complexity of existing software packages. This article…

Thermal degradation of Lewis acid complexed LDPE films

NASA Astrophysics Data System (ADS)

Sreelatha, K.; Predeep, P.

2017-06-01

The study highlights the thermal behavior of the semiconducting LDPE films synthesized by SbCl5 doping. The structural peculiarities and the responses of the structure to energetic modifications are studied. TGA and DTG curves are used to determine the thermal stability of the material. Degradation kinetics is elucidated. Activation energy and the entropy of activation for the degradation of the samples are calculated using Coats-Redfern plots and the samples show appreciable thermal stability.

Vibrational spectroscopy and molecular dynamics of water monomers and dimers adsorbed on polycyclic aromatic hydrocarbons.

PubMed

Simon, Aude; Rapacioli, Mathias; Mascetti, Joëlle; Spiegelman, Fernand

2012-05-21

This paper reports structures, energetics, dynamics and spectroscopy of H2O and (H2O)2 systems adsorbed on coronene (C24H12), a compact polycyclic aromatic hydrocarbon (PAH). On-the-fly Born-Oppenheimer molecular dynamics simulations are performed for temperatures T varying from 10 to 300 K, on a potential energy surface obtained within the self-consistent-charge density-functional based tight-binding (SCC-DFTB) approach. Anharmonic infrared (IR) spectra are extracted from these simulations. We first benchmark the SCC-DFTB semi-empirical hamiltonian vs. DFT (Density Functional Theory) calculations that include dispersion, on (C6H6)(H2O)1,2 small complexes. We find that charge corrections and inclusion of dispersion contributions in DFTB are necessary to obtain consistent structures, energetics and IR spectra. Using this Hamiltonian, the structures, energetics and IR features of the low-energy isomers of (C24H12)(H2O)1,2 are found to be similar to the DFT ones, with evidence for a stabilizing edge-coordination. The temperature dependence of the motions of H2O and (H2O)2 on the surface of C24H12 is analysed, revealing ultra-fast periodic motion. The water dimer starts diffusing at a higher temperature than the water monomer (150 K vs. 10 K respectively), which appears to be consistent with the binding energies. Qualitative and quantitative analyses of the effects of T on the IR spectra are performed. Anharmonic factors in particular are derived and it is shown that they can be used as signatures for the presence of PAH-water complexes. Finally, this paper lays the foundations for the studies of larger (PAH)m(H2O)n clusters, that can be treated with the efficient computational approach benchmarked in this paper.

Ab initio multiple spawning dynamics study of dimethylnitramine and dimethylnitramine-Fe complex to model their ultrafast nonadiabatic chemistry

NASA Astrophysics Data System (ADS)

Bera, Anupam; Ghosh, Jayanta; Bhattacharya, Atanu

2017-07-01

Conical intersections are now firmly established to be the key features in the excited electronic state processes of polyatomic energetic molecules. In the present work, we have explored conical intersection-mediated nonadiabatic chemical dynamics of a simple analogue nitramine molecule, dimethylnitramine (DMNA, containing one N-NO2 energetic group), and its complex with an iron atom (DMNA-Fe). For this task, we have used the ab initio multiple spawning (AIMS) dynamics simulation at the state averaged-complete active space self-consistent field(8,5)/6-31G(d) level of theory. We have found that DMNA relaxes back to the ground (S0) state following electronic excitation to the S1 excited state [which is an (n,π*) excited state] with a time constant of approximately 40 fs. This AIMS result is in very good agreement with the previous surface hopping-result and femtosecond laser spectroscopy result. DMNA does not dissociate during this fast internal conversion from the S1 to the S0 state. DMNA-Fe also undergoes extremely fast relaxation from the upper S1 state to the S0 state; however, this relaxation pathway is dissociative in nature. DMNA-Fe undergoes initial Fe-O, N-O, and N-N bond dissociations during relaxation from the upper S1 state to the ground S0 state through the respective conical intersection. The AIMS simulation reveals the branching ratio of these three channels as N-N:Fe-O:N-O = 6:3:1 (based on 100 independent simulations). Furthermore, the AIMS simulation reveals that the Fe-O bond dissociation channel exhibits the fastest (time constant 24 fs) relaxation, while the N-N bond dissociation pathway features the slowest (time constant 128 fs) relaxation. An intermediate time constant (30 fs) is found for the N-O bond dissociation channel. This is the first nonadiabatic chemical dynamics study of metal-contained energetic molecules through conical intersections.

Energetics and genetics across the prokaryote-eukaryote divide

PubMed Central

2011-01-01

Background All complex life on Earth is eukaryotic. All eukaryotic cells share a common ancestor that arose just once in four billion years of evolution. Prokaryotes show no tendency to evolve greater morphological complexity, despite their metabolic virtuosity. Here I argue that the eukaryotic cell originated in a unique prokaryotic endosymbiosis, a singular event that transformed the selection pressures acting on both host and endosymbiont. Results The reductive evolution and specialisation of endosymbionts to mitochondria resulted in an extreme genomic asymmetry, in which the residual mitochondrial genomes enabled the expansion of bioenergetic membranes over several orders of magnitude, overcoming the energetic constraints on prokaryotic genome size, and permitting the host cell genome to expand (in principle) over 200,000-fold. This energetic transformation was permissive, not prescriptive; I suggest that the actual increase in early eukaryotic genome size was driven by a heavy early bombardment of genes and introns from the endosymbiont to the host cell, producing a high mutation rate. Unlike prokaryotes, with lower mutation rates and heavy selection pressure to lose genes, early eukaryotes without genome-size limitations could mask mutations by cell fusion and genome duplication, as in allopolyploidy, giving rise to a proto-sexual cell cycle. The side effect was that a large number of shared eukaryotic basal traits accumulated in the same population, a sexual eukaryotic common ancestor, radically different to any known prokaryote. Conclusions The combination of massive bioenergetic expansion, release from genome-size constraints, and high mutation rate favoured a protosexual cell cycle and the accumulation of eukaryotic traits. These factors explain the unique origin of eukaryotes, the absence of true evolutionary intermediates, and the evolution of sex in eukaryotes but not prokaryotes. Reviewers This article was reviewed by: Eugene Koonin, William Martin, Ford Doolittle and Mark van der Giezen. For complete reports see the Reviewers' Comments section. PMID:21714941

The families and friends of heavy drinkers: Caught in the cross-fire of policy change?

PubMed

O'May, Fiona; Whittaker, Anne; Black, Heather; Gill, Jan

2017-03-01

Research highlights the need to better understand the impact of alcohol-related harm on families and communities. Scottish policy initiatives to reduce alcohol consumption and alcohol-related harm include the planned introduction of a minimum unit price for alcohol. We aimed to explore existing and proposed changes in alcohol policy, from the standpoint of heavy drinkers, through accounts of their involvement and repercussions for family and friends. Interviews were conducted with 20 heavy drinkers, recruited from hospital alcohol treatment centres in Scotland's two largest cities. Participants were part of a larger longitudinal mixed methods study. Interviews explored experiences of alcohol-related harm and the impact, or potential impact, of alcohol policy changes on drinking patterns, risk-taking, consumption and wellbeing. Data coded for 'family and friends' were thematically analysed using a constant comparison method. Family and friends were portrayed as important for aiding moderation and abstinence, but more often for sustaining continued heavy drinking. Heavy drinkers with complex needs and those living in deprived communities suggested that increased alcohol prices could exacerbate the detrimental effect on their health and social circumstances, and that of their family, should their consumption remain excessive. Population level policy initiatives to reduce alcohol consumption, such as minimum unit pricing, will impact on the families and social networks of heavy drinkers in addition to the drinker. The most vulnerable may be affected disproportionately. Alcohol policy changes and evaluations need to consider consequences for drinkers, families and communities. [O'May F, Whittaker A, Black H, Gill J. The families and friends of heavy drinkers: Caught in the cross-fire of policy change? Drug Alcohol Rev 2017;36:192-199]. © 2016 Australasian Professional Society on Alcohol and other Drugs.

Multi-model-based interactive authoring environment for creating shareable medical knowledge.

PubMed

Ali, Taqdir; Hussain, Maqbool; Ali Khan, Wajahat; Afzal, Muhammad; Hussain, Jamil; Ali, Rahman; Hassan, Waseem; Jamshed, Arif; Kang, Byeong Ho; Lee, Sungyoung

2017-10-01

Technologically integrated healthcare environments can be realized if physicians are encouraged to use smart systems for the creation and sharing of knowledge used in clinical decision support systems (CDSS). While CDSSs are heading toward smart environments, they lack support for abstraction of technology-oriented knowledge from physicians. Therefore, abstraction in the form of a user-friendly and flexible authoring environment is required in order for physicians to create shareable and interoperable knowledge for CDSS workflows. Our proposed system provides a user-friendly authoring environment to create Arden Syntax MLM (Medical Logic Module) as shareable knowledge rules for intelligent decision-making by CDSS. Existing systems are not physician friendly and lack interoperability and shareability of knowledge. In this paper, we proposed Intelligent-Knowledge Authoring Tool (I-KAT), a knowledge authoring environment that overcomes the above mentioned limitations. Shareability is achieved by creating a knowledge base from MLMs using Arden Syntax. Interoperability is enhanced using standard data models and terminologies. However, creation of shareable and interoperable knowledge using Arden Syntax without abstraction increases complexity, which ultimately makes it difficult for physicians to use the authoring environment. Therefore, physician friendliness is provided by abstraction at the application layer to reduce complexity. This abstraction is regulated by mappings created between legacy system concepts, which are modeled as domain clinical model (DCM) and decision support standards such as virtual medical record (vMR) and Systematized Nomenclature of Medicine - Clinical Terms (SNOMED CT). We represent these mappings with a semantic reconciliation model (SRM). The objective of the study is the creation of shareable and interoperable knowledge using a user-friendly and flexible I-KAT. Therefore we evaluated our system using completeness and user satisfaction criteria, which we assessed through the system- and user-centric evaluation processes. For system-centric evaluation, we compared the implementation of clinical information modelling system requirements in our proposed system and in existing systems. The results suggested that 82.05% of the requirements were fully supported, 7.69% were partially supported, and 10.25% were not supported by our system. In the existing systems, 35.89% of requirements were fully supported, 28.20% were partially supported, and 35.89% were not supported. For user-centric evaluation, the assessment criterion was 'ease of use'. Our proposed system showed 15 times better results with respect to MLM creation time than the existing systems. Moreover, on average, the participants made only one error in MLM creation using our proposed system, but 13 errors per MLM using the existing systems. We provide a user-friendly authoring environment for creation of shareable and interoperable knowledge for CDSS to overcome knowledge acquisition complexity. The authoring environment uses state-of-the-art decision support-related clinical standards with increased ease of use. Copyright © 2017 Elsevier B.V. All rights reserved.

Modeling of substrate and inhibitor binding to phospholipase A2.

PubMed

Sessions, R B; Dauber-Osguthorpe, P; Campbell, M M; Osguthorpe, D J

1992-09-01

Molecular graphics and molecular mechanics techniques have been used to study the mode of ligand binding and mechanism of action of the enzyme phospholipase A2. A substrate-enzyme complex was constructed based on the crystal structure of the apoenzyme. The complex was minimized to relieve initial strain, and the structural and energetic features of the resultant complex analyzed in detail, at the molecular and residue level. The minimized complex was then used as a basis for examining the action of the enzyme on modified substrates, binding of inhibitors to the enzyme, and possible reaction intermediate complexes. The model is compatible with the suggested mechanism of hydrolysis and with experimental data about stereoselectivity, efficiency of hydrolysis of modified substrates, and inhibitor potency. In conclusion, the model can be used as a tool in evaluating new ligands as possible substrates and in the rational design of inhibitors, for the therapeutic treatment of diseases such as rheumatoid arthritis, atherosclerosis, and asthma.

Energetic composite and system with enhanced mechanical sensitivity to initiation of self-sustained reaction

DOEpatents

Gash, Alexander E [Brentwood, CA; Barbee, Jr., Troy W.

2012-05-29

An energetic composition and system using amassed energetic multilayer pieces which are formed from the division, such as for example by cutting, scoring, breaking, crushing, shearing, etc., of a mechanically activatable monolithic energetic multilayer(s) (e.g. macro-scale sheets of multilayer films), for enhancing the sensitivity of the energetic composite and system to mechanical initiation of self-sustained reaction. In particular, mechanical initiation of the energetic composition may be achieved with significantly lower mechanical energy inputs than that typically required for initiating the monolithic energetic multilayers from which it is derived.

Stern Layer Structure and Energetics at Mica-Water Interfaces

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

Bourg, Ian C.; Lee, Sang Soo; Fenter, Paul

2017-04-11

The screening of surface charge by dissolved ions at solid liquid interfaces in the region of interfacial fluid known as the electrical double layer (EDL)-plays a recurrent role in surface science, from ion adsorption to colloidal mechanics to the transport properties of nanoporous media. A persistent unknown in theories of EDL-related phenomena is the structure of the Stern layer, the near-surface portion of the EDL where water molecules and adsorbed ions form specific short-range interactions with surface atoms. Here, we describe a set of synchrotron X-ray reflectivity (XRR) experiments and molecular dynamics (MD) simulations carried out under identical conditions formore » a range of 0.1 M alkali chloride (Li-, Na-, K-, Rb-, or CsCl) solutions on the basal surface of muscovite mica, a mineral isostructural to phyllosilicate clay minerals and one of the most widely studied reference surfaces in interfacial science. Our XRR and MD simulation results provide a remarkably consistent view of the structure and energetics of the Stern layer, with some discrepancy on the fraction of the minor outer-sphere component of Rb and on the adsorption energetics of Li. The results of both techniques, along with surface complexation model calculations, provide insight into the sensitivity of water structure and ion adsorption to surface topography and the type of adsorbed counterion.« less

Parametrization of DFTB3/3OB for Magnesium and Zinc for Chemical and Biological Applications

PubMed Central

2015-01-01

We report the parametrization of the approximate density functional theory, DFTB3, for magnesium and zinc for chemical and biological applications. The parametrization strategy follows that established in previous work that parametrized several key main group elements (O, N, C, H, P, and S). This 3OB set of parameters can thus be used to study many chemical and biochemical systems. The parameters are benchmarked using both gas-phase and condensed-phase systems. The gas-phase results are compared to DFT (mostly B3LYP), ab initio (MP2 and G3B3), and PM6, as well as to a previous DFTB parametrization (MIO). The results indicate that DFTB3/3OB is particularly successful at predicting structures, including rather complex dinuclear metalloenzyme active sites, while being semiquantitative (with a typical mean absolute deviation (MAD) of ∼3–5 kcal/mol) for energetics. Single-point calculations with high-level quantum mechanics (QM) methods generally lead to very satisfying (a typical MAD of ∼1 kcal/mol) energetic properties. DFTB3/MM simulations for solution and two enzyme systems also lead to encouraging structural and energetic properties in comparison to available experimental data. The remaining limitations of DFTB3, such as the treatment of interaction between metal ions and highly charged/polarizable ligands, are also discussed. PMID:25178644

Impact of multiple joint impairments on the energetics and mechanics of walking in patients with haemophilia.

PubMed

Lobet, S; Detrembleur, C; Hermans, C

2013-03-01

Few studies have assessed the changes produced by multiple joint impairments (MJI) of the lower limbs on gait in patients with haemophilia (PWH). In patients with MJI, quantifiable outcome measures are necessary if treatment benefits are to be compared. This study was aimed at observing the metabolic cost, mechanical work and efficiency of walking among PWH with MJI and to investigate the relationship between joint damage and any changes in mechanical and energetic variables. This study used three-dimensional gait analysis to investigate the kinematics, cost, mechanical work and efficiency of walking in 31 PWH with MJI, with the results being compared with speed-matched values from a database of healthy subjects. Regarding energetics, the mass-specific net cost of transport (C(net)) was significantly higher for PWH with MJI compared with control and directly related to a loss in dynamic joint range of motion. Surprisingly, however, there was no substantial increase in mechanical work, with PWH being able to adopt a walking strategy to improve energy recovery via the pendulum mechanism. This probable compensatory mechanism to economize energy likely counterbalances the supplementary work associated with an increased vertical excursion of centre of mass (CoM) and lower muscle efficiency of locomotion. Metabolic variables were probably the most representative variables of gait disability for these subjects with complex orthopaedic degenerative disorders. © 2012 Blackwell Publishing Ltd.

An electrothermal plasma model considering polyethylene and copper ablation based on ignition experiment

NASA Astrophysics Data System (ADS)

Zhang, Jiangbo; Li, Xingwen; Hang, Yuhua; Yang, Weihong

2018-06-01

In order to study the characteristics of electrothermal plasma interaction with energetic materials, especially the ignition ability, a novel model considering polyethylene and copper ablation is developed, and an ignition experiment system is set up. The parameters of the plasma and the surface conditions of the energetic materials are measured in the testing. The results show the measured first peak pressure to be ~2.2 MPa, the second peak pressure to be ~3.9 MPa, and the visible flame velocity to be ~2000 m s‑1. Circular pits of the order of microns and nanometers in size are observed on the surface of the energetic materials. Further, the parameters of the plasma, including static pressure, total pressure, density, temperature, velocity, copper concentration and PE concentration, are calculated and analyzed by the established model, under discharge currents of 9 kA. The simulation is similar to those of experimental results. A shock wave is observed in the experiment and is presented in the calculations; it plays an important role in the performance of the plasma in the nozzle region, where the parameters of the plasma variation trends are very complex. With the aim of obtaining the overall performance of the plasma, the coupling characteristics of multiple parameters must be taken into account, in accordance with the developed electrothermal plasma model.

Computer-aided drug design of falcipain inhibitors: virtual screening, structure-activity relationships, hydration site thermodynamics, and reactivity analysis.

PubMed

Shah, Falgun; Gut, Jiri; Legac, Jennifer; Shivakumar, Devleena; Sherman, Woody; Rosenthal, Philip J; Avery, Mitchell A

2012-03-26

Falcipains (FPs) are hemoglobinases of Plasmodium falciparum that are validated targets for the development of antimalarial chemotherapy. A combined ligand- and structure-based virtual screening of commercial databases was performed to identify structural analogs of virtual screening hits previously discovered in our laboratory. A total of 28 low micromolar inhibitors of FP-2 and FP-3 were identified and the structure-activity relationship (SAR) in each series was elaborated. The SAR of the compounds was unusually steep in some cases and could not be explained by a traditional analysis of the ligand-protein interactions (van der Waals, electrostatics, and hydrogen bonds). To gain further insights, a statistical thermodynamic analysis of explicit solvent in the ligand binding domains of FP-2 and FP-3 was carried out to understand the roles played by water molecules in binding of these inhibitors. Indeed, the energetics associated with the displacement of water molecules upon ligand binding explained some of the complex trends in the SAR. Furthermore, low potency of a subset of FP-2 inhibitors that could not be understood by the water energetics was explained in the context of poor chemical reactivity of the reactive centers of these compounds. The present study highlights the importance of considering energetic contributors to binding beyond traditional ligand-protein interactions. © 2012 American Chemical Society

Energetics of muscle contraction: the whole is less than the sum of its parts

NASA Technical Reports Server (NTRS)

Kushmerick, M. J.; Conley, K. E.

2002-01-01

Understanding muscle energetics is a problem in optimizing supply of ATP to the demands of ATPases. The complexity of reactions and their fluxes to achieve this balance is greatly reduced by recognizing constraints imposed by the integration of common metabolites at fixed stoichiometry among modular units. ATPase is driven externally. Oxidative phosphorylation and glycogenolysis are the suppliers. We focus on their regulation which involves different controls, but reduces to two principles that enable facile experimental analysis of the supply and demand fluxes. The ratio of concentration of phosphocreatine (PCr) to ATP, not their individual values, sets the range of achievable concentrations of ADP in resting and active muscle (at fixed pH) in different cell types. This principle defines the fraction of available flux of oxidative phosphorylation utilized (at fixed enzyme activities). Then the kinetics of PCr recovery defines the kinetics of oxygen supply and substrate utilization. The second principle is the constancy of PCr and H(+) (lactate) production by glycogenolysis due to the coupling of ATPase and glycolysis. This principle enables glycogenolytic flux to be measured from intracellular proton loads. Further simplification occurs because the magnitude of the interacting fluxes and metabolite concentrations are specified within narrow limits when both the resting and active fluxes are quantified. Thus there is a small set of rules for assessing and understanding the thermodynamics and kinetics of muscle energetics.

Energetics of the terrestrial bow shock

NASA Astrophysics Data System (ADS)

Hamrin, Maria; Gunell, Herbert; Norqvist, Patrik

2017-04-01

The solar wind is the primary energy source for the magnetospheric energy budget. Energy can enter through the magnetopause both as kinetic energy (plasma entering via e.g. magnetic reconnection and impulsive penetration) and as electromagnetic energy (e.g. by the conversion of solar wind kinetic energy into electromagnetic energy in magnetopause generators). However, energy is extracted from the solar wind already at the bow shock, before it encounters the terrestrial magnetopause. At the bow shock the supersonic solar wind is slowed down and heated, and the region near the bow shock is known to host many complex processes, including the accelerating of particles and the generation of waves. The processes at and near the bow shock can be discussed in terms of energetics: In a generator (load) process kinetic energy is converted to (from) electromagnetic energy. Bow shock regions where the solar wind is decelerated correspond to generators, while regions where particles are energized (accelerated and heated) correspond to loads. Recently, it has been suggested that currents from the bow shock generator should flow across the magnetosheath and connect to the magnetospause current systems [Siebert and Siscoe, 2002; Lopez et al., 2011]. In this study we use data from the Magnetospheric MultiScale (MMS) mission to investigate the energetics of the bow shock and the current closure, and we compare with the MHD simulations of Lopez et al., 2011.

Investigating the Energetic Ordering of Stable and Metastable TiO 2 Polymorphs Using DFT+ U and Hybrid Functionals

DOE PAGES

Curnan, Matthew T.; Kitchin, John R.

2015-08-12

Prediction of transition metal oxide BO 2 (B = Ti, V, etc.) polymorph energetic properties is critical to tunable material design and identifying thermodynamically accessible structures. Determining procedures capable of synthesizing particular polymorphs minimally requires prior knowledge of their relative energetic favorability. Information concerning TiO 2 polymorph relative energetic favorability has been ascertained from experimental research. In this study, the consistency of first-principles predictions and experimental results involving the relative energetic ordering of stable (rutile), metastable (anatase and brookite), and unstable (columbite) TiO 2 polymorphs is assessed via density functional theory (DFT). Considering the issues involving electron–electron interaction and chargemore » delocalization in TiO 2 calculations, relative energetic ordering predictions are evaluated over trends varying Ti Hubbard U 3d or exact exchange fraction parameter values. Energetic trends formed from varying U 3d predict experimentally consistent energetic ordering over U 3d intervals when using GGA-based functionals, regardless of pseudopotential selection. Given pertinent linear response calculated Hubbard U values, these results enable TiO 2 polymorph energetic ordering prediction. Here, the hybrid functional calculations involving rutile–anatase relative energetics, though demonstrating experimentally consistent energetic ordering over exact exchange fraction ranges, are not accompanied by predicted fractions, for a first-principles methodology capable of calculating exact exchange fractions precisely predicting TiO 2 polymorph energetic ordering is not available.« less

Energetic materials and methods of tailoring electrostatic discharge sensitivity of energetic materials

DOEpatents

Daniels, Michael A.; Heaps, Ronald J.; Wallace, Ronald S.; Pantoya, Michelle L.; Collins, Eric S.

2016-11-01

An energetic material comprising an elemental fuel, an oxidizer or other element, and a carbon nanofiller or carbon fiber rods, where the carbon nanofiller or carbon fiber rods are substantially homogeneously dispersed in the energetic material. Methods of tailoring the electrostatic discharge sensitivity of an energetic material are also disclosed.

Combined effects of space charge and energetic disorder on photocurrent efficiency loss of field-dependent organic photovoltaic devices

NASA Astrophysics Data System (ADS)

Yoon, Sangcheol; Park, Byoungchoo; Hwang, Inchan

2015-11-01

The loss of photocurrent efficiency by space-charge effects in organic solar cells with energetic disorder was investigated to account for how energetic disorder incorporates space-charge effects, utilizing a drift-diffusion model with field-dependent charge-pair dissociation and suppressed bimolecular recombination. Energetic disorder, which induces the Poole-Frenkel behavior of charge carrier mobility, is known to decrease the mobility of charge carriers and thus reduces photovoltaic performance. We found that even if the mobilities are the same in the absence of space-charge effects, the degree of energetic disorder can be an additional parameter affecting photocurrent efficiency when space-charge effects occur. Introducing the field-dependence parameter that reflects the energetic disorder, the behavior of efficiency loss with energetic disorder can differ depending on which charge carrier is subject to energetic disorder. While the energetic disorder that is applied to higher-mobility charge carriers decreases photocurrent efficiency further, the efficiency loss can be suppressed when energetic disorder is applied to lower-mobility charge carriers.

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

Ellis, Ross J.; Brigham, Derek M.; Delmau, Laetitia

The subtle energetic differences underpinning adjacent lanthanide discrimination are explored with diglycolamide ligands. Our approach converges liquid–liquid extraction experiments with solution-phase X-ray absorption spectroscopy (XAS) and density functional theory (DFT) simulations, spanning the lanthanide series. The homoleptic [(DGA)3Ln]3+ complex was confirmed in the organic extractive solution by XAS, and this was modeled using DFT. An interplay between steric strain and coordination energies apparently gives rise to a nonlinear trend in discriminatory lanthanide ion complexation across the series. Our results highlight the importance of optimizing chelate molecular geometry to account for both coordination interactions and strain energies when designing new ligandsmore » for efficient adjacent lanthanide separation for rare-earth refining.« less

"Soft docking": matching of molecular surface cubes.

PubMed

Jiang, F; Kim, S H

1991-05-05

Molecular recognition is achieved through the complementarity of molecular surface structures and energetics with, most commonly, associated minor conformational changes. This complementarity can take many forms: charge-charge interaction, hydrogen bonding, van der Waals' interaction, and the size and shape of surfaces. We describe a method that exploits these features to predict the sites of interactions between two cognate molecules given their three-dimensional structures. We have developed a "cube representation" of molecular surface and volume which enables us not only to design a simple algorithm for a six-dimensional search but also to allow implicitly the effects of the conformational changes caused by complex formation. The present molecular docking procedure may be divided into two stages. The first is the selection of a population of complexes by geometric "soft docking", in which surface structures of two interacting molecules are matched with each other, allowing minor conformational changes implicitly, on the basis of complementarity in size and shape, close packing, and the absence of steric hindrance. The second is a screening process to identify a subpopulation with many favorable energetic interactions between the buried surface areas. Once the size of the subpopulation is small, one may further screen to find the correct complex based on other criteria or constraints obtained from biochemical, genetic, and theoretical studies, including visual inspection. We have tested the present method in two ways. First is a control test in which we docked the components of a molecular complex of known crystal structure available in the Protein Data Bank (PDB). Two molecular complexes were used: (1) a ternary complex of dihydrofolate reductase, NADPH and methotrexate (3DFR in PDB) and (2) a binary complex of trypsin and trypsin inhibitor (2PTC in PDB). The components of each complex were taken apart at an arbitrary relative orientation and then docked together again. The results show that the geometric docking alone is sufficient to determine the correct docking solutions in these ideal cases, and that the cube representation of the molecules does not degrade the docking process in the search for the correct solution. The second is the more realistic experiment in which we docked the crystal structures of uncomplexed molecules and then compared the structures of docked complexes with the crystal structures of the corresponding complexes. This is to test the capability of our method in accommodating the effects of the conformational changes in the binding sites of the molecules in docking.(ABSTRACT TRUNCATED AT 400 WORDS)

A Participatory Action Research Approach to Developing Youth-Friendly Strategies for the Prevention of Teenage Pregnancy

ERIC Educational Resources Information Center

Wood, Lesley; Hendricks, Farah

2017-01-01

Teenage pregnancy among school-going youth is a concern worldwide, but in socially-economically challenged environments it is a result of, and contributory factor to, a complex web of social injustice. In South Africa, most of the school-based prevention interventions to date have been adult-designed and imparted, with the voice of the target…

Earth Day 2018 Activities

NASA Image and Video Library

2018-04-17

David Bell of Renew Merchandise was one of 50 exhibitors offering information on a variety of topics, including electric vehicles, sustainable lighting, renewable energy, Florida-friendly landscaping tips, Florida’s biking trails and more. The event took place during the annual Earth Day celebration at the Kennedy Space Center Visitor Complex, guests have an opportunity to learn more about energy awareness, the environment and sustainability.

Chua's Circuit and the Qualitative Theory of Dynamical Systems

NASA Astrophysics Data System (ADS)

Mira, Christian

Simple electronic oscillators were at the origin of many studies related to the qualitative theory of dynamical systems. Chua's circuit ([Chua, 1992; Madan, 1993; Chua, 1993; Chua & Pivka, 1995; Wu & Chua, 1996; Pivka et al., 1996]) is now playing an equivalent role for the generation and understanding of complex dynamics. In honour of my friend Leon Chua on his 60th birthday.

Towards an Adolescent Friendly Methodology: Accessing the Authentic through Collective Reflection

ERIC Educational Resources Information Center

Keeffe, Mary; Andrews, Dorothy

2015-01-01

The re-emergence of student voice presents a challenge to schools and researchers to become more responsive to the voice of adolescents in education and in research. However, the poor articulation of the nature of student voice to date is confirmation of the complex and important nature of the personal advocacy and human agency that is involved in…

Services for Graduate Students: A Review of Academic Library Web Sites

ERIC Educational Resources Information Center

Rempel, Hannah Gascho

2010-01-01

A library's Web site is well recognized as the gateway to the library for the vast majority of users. Choosing the most user-friendly Web architecture to reflect the many services libraries offer is a complex process, and librarians are still experimenting to find what works best for their users. As part of a redesign of the Oregon State…

New Data Products and Tools from STEREO's IMPACT Investigation

NASA Astrophysics Data System (ADS)

Schroeder, P. C.; Luhmann, J. G.; Li, Y.; Huttunen, E.; Toy, V.; Russell, C. T.; Davis, A.

2008-05-01

STEREO's IMPACT (In-situ Measurements of Particles and CME Transients) investigation provides the first opportunity for long duration, detailed observations of 1 AU magnetic field structures, plasma and suprathermal electrons, and energetic particles at points bracketing Earth's heliospheric location. The IMPACT team has developed both human-friendly web portals and API's (application program interfaces) which provide straight- foward data access to scientists and the Virtual Observatories. Several new data products and web features have been developed including the release of more and higher-level data products, a library of TPLOT-based IDL data analysis routines, and web sites devoted to event analysis and inter-mission and inter-disciplinary collaboration. A web browser integrating STEREO and L1 in situ data with imaging and models provides a powerful venue for exploring the Sun-Earth connection. These latest releases enable the larger scientific community to use STEREO's unique in-situ data in novel ways along side "third eye" data sets from Wind, ACE and other heliospheric missions contributing to a better understanding of three dimensional structures in the solar wind.

New solvent-stabilized few-layer black phosphorus for antibacterial applications.

PubMed

Sun, Zhenyu; Zhang, Yuqin; Yu, Hao; Yan, Chao; Liu, Yongchao; Hong, Song; Tao, Hengcong; Robertson, Alex W; Wang, Zhuo; Pádua, Agílio A H

2018-06-22

Discovering highly efficient, environmentally friendly, and low-cost exfoliating media that can both disperse and protect black phosphorus (BP) remains a challenge. Herein, we demonstrate such a new molecule, N,N'-dimethylpropyleneurea (DMPU), for effective exfoliation and dispersion of two-dimensional BP nanosheets. A very high exfoliation efficiency of up to 16% was achieved in DMPU, significantly surpassing other good solvents. Exfoliated flakes are free from structural disorder or oxidation. Nanosheets retain high stability in DMPU even after addition of 25 vol% of common solvents. The solvation shell appears to protect the nanosheets from reacting with water and air, more remarkably than the best solvent N-cyclohexyl-2-pyrrolidone reported so far. Molecular dynamics simulations of the exfoliation process show that DMPU is among the effective solvents, although energetically it does not appear as favorable as some other amides. We also demonstrate that our exfoliated BP nanosheets exhibit excellent antimicrobial activities against both Escherichia coli and Staphylococcus aureus, outperforming other common two-dimensional materials of graphene and MoS2, suggesting promise in biomedical applications.

Measuring fish and their physical habitats: Versatile 2D and 3D video techniques with user-friendly software

USGS Publications Warehouse

Neuswanger, Jason R.; Wipfli, Mark S.; Rosenberger, Amanda E.; Hughes, Nicholas F.

2017-01-01

Applications of video in fisheries research range from simple biodiversity surveys to three-dimensional (3D) measurement of complex swimming, schooling, feeding, and territorial behaviors. However, researchers lack a transparently developed, easy-to-use, general purpose tool for 3D video measurement and event logging. Thus, we developed a new measurement system, with freely available, user-friendly software, easily obtained hardware, and flexible underlying mathematical methods capable of high precision and accuracy. The software, VidSync, allows users to efficiently record, organize, and navigate complex 2D or 3D measurements of fish and their physical habitats. Laboratory tests showed submillimetre accuracy in length measurements of 50.8 mm targets at close range, with increasing errors (mostly <1%) at longer range and for longer targets. A field test on juvenile Chinook salmon (Oncorhynchus tshawytscha) feeding behavior in Alaska streams found that individuals within aggregations avoided the immediate proximity of their competitors, out to a distance of 1.0 to 2.9 body lengths. This system makes 3D video measurement a practical tool for laboratory and field studies of aquatic or terrestrial animal behavior and ecology.

Ion mobility-mass spectrometry as a tool to investigate protein-ligand interactions.

PubMed

Göth, Melanie; Pagel, Kevin

2017-07-01

Ion mobility-mass spectrometry (IM-MS) is a powerful tool for the simultaneous analysis of mass, charge, size, and shape of ionic species. It allows the characterization of even low-abundant species in complex samples and is therefore particularly suitable for the analysis of proteins and their assemblies. In the last few years even complex and intractable species have been investigated successfully with IM-MS and the number of publications in this field is steadily growing. This trend article highlights recent advances in which IM-MS was used to study protein-ligand complexes and in particular focuses on the catch and release (CaR) strategy and collision-induced unfolding (CIU). Graphical Abstract Native mass spectrometry and ion mobility-mass spectrometry are versatile tools to follow the stoichiometry, energetics, and structural impact of protein-ligand binding.

Interstate vibronic coupling constants between electronic excited states for complex molecules

NASA Astrophysics Data System (ADS)

Fumanal, Maria; Plasser, Felix; Mai, Sebastian; Daniel, Chantal; Gindensperger, Etienne

2018-03-01

In the construction of diabatic vibronic Hamiltonians for quantum dynamics in the excited-state manifold of molecules, the coupling constants are often extracted solely from information on the excited-state energies. Here, a new protocol is applied to get access to the interstate vibronic coupling constants at the time-dependent density functional theory level through the overlap integrals between excited-state adiabatic auxiliary wavefunctions. We discuss the advantages of such method and its potential for future applications to address complex systems, in particular, those where multiple electronic states are energetically closely lying and interact. We apply the protocol to the study of prototype rhenium carbonyl complexes [Re(CO)3(N,N)(L)]n+ for which non-adiabatic quantum dynamics within the linear vibronic coupling model and including spin-orbit coupling have been reported recently.

Variation of M···H-C Interactions in Square-Planar Complexes of Nickel(II), Palladium(II), and Platinum(II) Probed by Luminescence Spectroscopy and X-ray Diffraction at Variable Pressure.

PubMed

Poirier, Stéphanie; Lynn, Hudson; Reber, Christian; Tailleur, Elodie; Marchivie, Mathieu; Guionneau, Philippe; Probert, Michael R

2018-06-12

Luminescence spectra of isoelectronic square-planar d 8 complexes with 3d, 4d, and 5d metal centers show d-d luminescence with an energetic order different from that of the spectrochemical series, indicating that additional structural effects, such as different ligand-metal-ligand angles, are important factors. Variable-pressure luminescence spectra of square-planar nickel(II), palladium(II), and platinum(II) complexes with dimethyldithiocarbamate ({CH 3 } 2 DTC) ligands and their deuterated analogues show unexpected variations of the shifts of their maxima. High-resolution crystal structures and crystal structures at variable pressure for [Pt{(CH 3 ) 2 DTC} 2 ] indicate that intermolecular M···H-C interactions are at the origin of these different shifts.

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

Zhu, Bei; Liu, Ying D.; Hu, Huidong

We study the solar energetic particle (SEP) event associated with the 2012 July 23 extreme solar storm, for which Solar Terrestrial Relations Observatory (STEREO) and the spacecraft at L1 provide multi-point remote sensing and in situ observations. The extreme solar storm, with a superfast shock and extremely enhanced ejecta magnetic fields observed near 1 au at STEREO A , was caused by the combination of successive coronal mass ejections (CMEs). Meanwhile, energetic particles were observed by STEREO and near-Earth spacecraft such as the Advanced Composition Explorer and SOlar and Heliospheric Observatory , suggesting a wide longitudinal spread of the particlesmore » at 1 au. Combining the SEP observations with in situ plasma and magnetic field measurements, we investigate the longitudinal distribution of the SEP event in connection with the associated shock and CMEs. Our results underscore the complex magnetic configuration of the inner heliosphere formed by solar eruptions. Examination of particle intensities, proton anisotropy distributions, element abundance ratios, magnetic connectivity, and spectra also gives important clues for particle acceleration, transport, and distribution.« less

Extensive site-directed mutagenesis reveals interconnected functional units in the alkaline phosphatase active site

PubMed Central

Sunden, Fanny; Peck, Ariana; Salzman, Julia; Ressl, Susanne; Herschlag, Daniel

2015-01-01

Enzymes enable life by accelerating reaction rates to biological timescales. Conventional studies have focused on identifying the residues that have a direct involvement in an enzymatic reaction, but these so-called ‘catalytic residues’ are embedded in extensive interaction networks. Although fundamental to our understanding of enzyme function, evolution, and engineering, the properties of these networks have yet to be quantitatively and systematically explored. We dissected an interaction network of five residues in the active site of Escherichia coli alkaline phosphatase. Analysis of the complex catalytic interdependence of specific residues identified three energetically independent but structurally interconnected functional units with distinct modes of cooperativity. From an evolutionary perspective, this network is orders of magnitude more probable to arise than a fully cooperative network. From a functional perspective, new catalytic insights emerge. Further, such comprehensive energetic characterization will be necessary to benchmark the algorithms required to rationally engineer highly efficient enzymes. DOI: http://dx.doi.org/10.7554/eLife.06181.001 PMID:25902402

The Role of Deformation Energetics in Long-Term Tectonic Modeling

NASA Astrophysics Data System (ADS)

Ahamed, S.; Choi, E.

2017-12-01

The deformation-related energy budget is usually considered in the simplest form or even entirely omitted from the energy balance equation. We derive a full energy balance equation that accounts not only for heat energy but also for mechanical (elastic, plastic and viscous) work. The derived equation is implemented in DES3D, an unstructured finite element solver for long-term tectonic deformation. We verify the implementation by comparing numerical solutions to the corresponding semi-analytic solutions in three benchmarks extended from the classical oedometer test. We also investigate the long-term effects of deformation energetics on the evolution of large offset normal faults. We find that the models considering the full energy balance equation tend to produce more secondary faults and an elongated core complex. Our results for the normal fault system confirm that persistent inelastic deformation has a significant impact on the long-term evolution of faults, motivating further exploration of the role of the full energy balance equation in other geodynamic systems.

Cooperative Metal+Ligand Oxidative Addition and Sigma-Bond Metathesis: A DFT Study

DOE PAGES

Lopez, Kent G.; Cundari, Thomas R.; Gary, J. Brannon

2018-01-17

A computational study of the experimentally proposed mechanism of alkyne diboration by a PDICo complex yielded two fundamental catalytic steps that undergo remarkable electronic changes, PDI = bis(imino)-pyridine. The reactions are envisaged via DFT (density functional theory) and MCSCF (multi-configuration self-consistent field) simulations as (i) a cooperative metal+ligand oxidative addition, and (ii) a sigma-bond metathesis induced ligand-to-metal charge transfer. Analysis of the bonding of pertinent intermediates/TSs also yielded important insight that may be illuminating with regards to the larger field of green catalysis that seeks to ennoble base metals through synergy with potentially redox non-innocent (RNI) ligands. For the presentmore » case, massive changes in electronic structure do not incur massive energetic penalties. Finally, in conjunction with previous research, one may postulate that structural and energetic “fluidity” among several electronic states of RNI-M 3d along the reaction coordinate is an essential signature of redox cooperativity and thus ennoblement.« less

Large predatory coral trout species unlikely to meet increasing energetic demands in a warming ocean.

PubMed

Johansen, J L; Pratchett, M S; Messmer, V; Coker, D J; Tobin, A J; Hoey, A S

2015-09-08

Increased ocean temperature due to climate change is raising metabolic demands and energy requirements of marine ectotherms. If productivity of marine systems and fisheries are to persist, individual species must compensate for this demand through increasing energy acquisition or decreasing energy expenditure. Here we reveal that the most important coral reef fishery species in the Indo-west Pacific, the large predatory coral trout Plectropomus leopardus (Serranidae), can behaviourally adjust food intake to maintain body-condition under elevated temperatures, and acclimate over time to consume larger meals. However, these increased energetic demands are unlikely to be met by adequate production at lower trophic levels, as smaller prey species are often the first to decline in response to climate-induced loss of live coral and structural complexity. Consequently, ubiquitous increases in energy consumption due to climate change will increase top-down competition for a dwindling biomass of prey, potentially distorting entire food webs and associated fisheries.

Calibration of imaging plate detectors to mono-energetic protons in the range 1-200 MeV

NASA Astrophysics Data System (ADS)

Rabhi, N.; Batani, D.; Boutoux, G.; Ducret, J.-E.; Jakubowska, K.; Lantuejoul-Thfoin, I.; Nauraye, C.; Patriarca, A.; Saïd, A.; Semsoum, A.; Serani, L.; Thomas, B.; Vauzour, B.

2017-11-01

Responses of Fuji Imaging Plates (IPs) to proton have been measured in the range 1-200 MeV. Mono-energetic protons were produced with the 15 MV ALTO-Tandem accelerator of the Institute of Nuclear Physics (Orsay, France) and, at higher energies, with the 200-MeV isochronous cyclotron of the Institut Curie—Centre de Protonthérapie d'Orsay (Orsay, France). The experimental setups are described and the measured photo-stimulated luminescence responses for MS, SR, and TR IPs are presented and compared to existing data. For the interpretation of the results, a sensitivity model based on the Monte Carlo GEANT4 code has been developed. It enables the calculation of the response functions in a large energy range, from 0.1 to 200 MeV. Finally, we show that our model reproduces accurately the response of more complex detectors, i.e., stack of high-Z filters and IPs, which could be of great interest for diagnostics of Petawatt laser accelerated particles.

A case study of magnetotail current sheet disruption and diversion

NASA Technical Reports Server (NTRS)

Lui, A. T. Y.; Lopez, R. E.; Krimigis, S. M.; Mcentire, R. W.; Zanetti, L. J.

1988-01-01

On June 1, 1985 the AMPTE/CCE spacecraft (at a geocentric distance of about 8.8 earth radii at the midnight neutral sheet region) observed a dispersionless energetic particle injection and an increase in magnetic field magnitude, which are features commonly attributed to disruption of the near-earth cross-tail current sheet during substorm expansion onsets. An analysis based on high time-resolution measurements from the magnetometer and the energetic particle detector indicates that the current sheet disruption region exhibited localized (less than 1 earth radius) and transient (less than 1 min) particle intensity enhancements, accompanied by complex magnetic field changes with occasional development of a southward magnetic field component. Similar features are seen in other current disruption/diversion events observed by the CCE. The present analysis suggests that the current disruption region is quite turbulent, similar to laboratory experiments on current sheet disruption, with signatures unlike those expected from an X-type neutral line configuration. No clear indication of periodicity in any magnetic field parameter is discernible for this current disruption event.

Material and morphology parameter sensitivity analysis in particulate composite materials

NASA Astrophysics Data System (ADS)

Zhang, Xiaoyu; Oskay, Caglar

2017-12-01

This manuscript presents a novel parameter sensitivity analysis framework for damage and failure modeling of particulate composite materials subjected to dynamic loading. The proposed framework employs global sensitivity analysis to study the variance in the failure response as a function of model parameters. In view of the computational complexity of performing thousands of detailed microstructural simulations to characterize sensitivities, Gaussian process (GP) surrogate modeling is incorporated into the framework. In order to capture the discontinuity in response surfaces, the GP models are integrated with a support vector machine classification algorithm that identifies the discontinuities within response surfaces. The proposed framework is employed to quantify variability and sensitivities in the failure response of polymer bonded particulate energetic materials under dynamic loads to material properties and morphological parameters that define the material microstructure. Particular emphasis is placed on the identification of sensitivity to interfaces between the polymer binder and the energetic particles. The proposed framework has been demonstrated to identify the most consequential material and morphological parameters under vibrational and impact loads.

Extensive site-directed mutagenesis reveals interconnected functional units in the alkaline phosphatase active site

DOE PAGES

Sunden, Fanny; Peck, Ariana; Salzman, Julia; ...

2015-04-22

Enzymes enable life by accelerating reaction rates to biological timescales. Conventional studies have focused on identifying the residues that have a direct involvement in an enzymatic reaction, but these so-called ‘catalytic residues’ are embedded in extensive interaction networks. Although fundamental to our understanding of enzyme function, evolution, and engineering, the properties of these networks have yet to be quantitatively and systematically explored. We dissected an interaction network of five residues in the active site of Escherichia coli alkaline phosphatase. Analysis of the complex catalytic interdependence of specific residues identified three energetically independent but structurally interconnected functional units with distinct modesmore » of cooperativity. From an evolutionary perspective, this network is orders of magnitude more probable to arise than a fully cooperative network. From a functional perspective, new catalytic insights emerge. Further, such comprehensive energetic characterization will be necessary to benchmark the algorithms required to rationally engineer highly efficient enzymes.« less

Cooperative Metal+Ligand Oxidative Addition and Sigma-Bond Metathesis: A DFT Study

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

Lopez, Kent G.; Cundari, Thomas R.; Gary, J. Brannon

A computational study of the experimentally proposed mechanism of alkyne diboration by a PDICo complex yielded two fundamental catalytic steps that undergo remarkable electronic changes, PDI = bis(imino)-pyridine. The reactions are envisaged via DFT (density functional theory) and MCSCF (multi-configuration self-consistent field) simulations as (i) a cooperative metal+ligand oxidative addition, and (ii) a sigma-bond metathesis induced ligand-to-metal charge transfer. Analysis of the bonding of pertinent intermediates/TSs also yielded important insight that may be illuminating with regards to the larger field of green catalysis that seeks to ennoble base metals through synergy with potentially redox non-innocent (RNI) ligands. For the presentmore » case, massive changes in electronic structure do not incur massive energetic penalties. Finally, in conjunction with previous research, one may postulate that structural and energetic “fluidity” among several electronic states of RNI-M 3d along the reaction coordinate is an essential signature of redox cooperativity and thus ennoblement.« less

Large predatory coral trout species unlikely to meet increasing energetic demands in a warming ocean

PubMed Central

Johansen, J.L.; Pratchett, M.S.; Messmer, V.; Coker, D.J.; Tobin, A.J.; Hoey, A.S.

2015-01-01

Increased ocean temperature due to climate change is raising metabolic demands and energy requirements of marine ectotherms. If productivity of marine systems and fisheries are to persist, individual species must compensate for this demand through increasing energy acquisition or decreasing energy expenditure. Here we reveal that the most important coral reef fishery species in the Indo-west Pacific, the large predatory coral trout Plectropomus leopardus (Serranidae), can behaviourally adjust food intake to maintain body-condition under elevated temperatures, and acclimate over time to consume larger meals. However, these increased energetic demands are unlikely to be met by adequate production at lower trophic levels, as smaller prey species are often the first to decline in response to climate-induced loss of live coral and structural complexity. Consequently, ubiquitous increases in energy consumption due to climate change will increase top-down competition for a dwindling biomass of prey, potentially distorting entire food webs and associated fisheries. PMID:26345733

Metastable States Arising from the Ablation of Solid Copper

NASA Astrophysics Data System (ADS)

Andrejeva, Anna; Harris, Joe; Wright, Tim

2014-06-01

Laser ablation is a popular method for generating metal atoms so that metal clusters, complexes, and molecules may be investigated in gas phase spectroscopic studies. However, the initial production of a highly energetic metal plasma from the surface of a solid metal target can produce atoms which are not in their ground electronic state, and consequently atomic spectra can become quite complicated due to transitions arising from metastable atomic excited states which remain populated on the experimental timescale. Presented herein are details of the laser vaporisation source in use by our group. Spectra of atomic copper are presented, recorded via (1+1') and (2+1) resonance enhanced multiphoton ionisation (REMPI) spectroscopy. The energetic regions examined are expected to correspond to the (4s24p) 2P ← 2S and the (4s2nd) 2D ← 2S Rydberg series respectively, but the observed spectra also exhibit many additional contributions which are found to arise from electronically excited states, and these will be discussed.

Steric Effects of Solvent Molecules on SN2 Substitution Dynamics.

PubMed

Liu, Xu; Xie, Jing; Zhang, Jiaxu; Yang, Li; Hase, William L

2017-04-20

Influences of solvent molecules on S N 2 reaction dynamics of microsolvated F - (H 2 O) n with CH 3 I, for n = 0-3, are uncovered by direct chemical dynamics simulations. The direct substitution mechanism, which is important without microsolvation, is quenched dramatically upon increasing hydration. The water molecules tend to force reactive encounters to proceed through the prereaction collision complex leading to indirect reaction. In contrast to F - (H 2 O), reaction with higher hydrated ions shows a strong propensity for ion desolvation in the entrance channel, diminishing steric hindrance for nucleophilic attack. Thus, nucleophilic substitution avoids the potential energy barrier with all of the solvent molecules intact and instead occurs through the less solvated barrier, which is energetically unexpected because the former barrier has a lower energy. The work presented here reveals a trade-off between reaction energetics and steric effects, with the latter found to be crucial in understanding how hydration influences microsolvated S N 2 dynamics.

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.

Effect of microstructure on the coupled electromagnetic-thermo-mechanical response of cyclotrimethylenetrinitramine-estane energetic aggregates to infrared laser radiation

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

Brown, Judith A.; Zikry, M. A., E-mail: zikry@ncsu.edu

2015-09-28

The coupled electromagnetic (EM)-thermo-mechanical response of cyclotrimethylenetrinitramine-estane energetic aggregates under laser irradiation and high strain rate loads has been investigated for various aggregate sizes and binder volume fractions. The cyclotrimethylenetrinitramine (RDX) crystals are modeled with a dislocation density-based crystalline plasticity formulation and the estane binder is modeled with finite viscoelasticity through a nonlinear finite element approach that couples EM wave propagation with laser heat absorption, thermal conduction, and inelastic deformation. Material property and local behavior mismatch at the crystal-binder interfaces resulted in geometric scattering of the EM wave, electric field and laser heating localization, high stress gradients, dislocation density, andmore » crystalline shear slip accumulation. Viscous sliding in the binder was another energy dissipation mechanism that reduced stresses in aggregates with thicker binder ligaments and larger binder volume fractions. This investigation indicates the complex interactions between EM waves and mechanical behavior, for accurate predictions of laser irradiation of heterogeneous materials.« less

Scaling violation in fragmentation region at energies above 10-15 eV based on the data on cosmic ray hadron component

NASA Technical Reports Server (NTRS)

1985-01-01

The ratio of intensity of energetic hadrons, having no visible accompaniment, to the total flux of hadrons of the same energy at 4380m above sea level is given. The ratio is much more than expected for scaling model with proton primaries. This result could not be explained by complex chemical composition of primary cosmic ray and indicates the scaling violation in fragmentation region.

On the Surface Formation of NH3 and HNCO in Dark Molecular Clouds - Searching for Wöhler Synthesis in the Interstellar Medium

NASA Astrophysics Data System (ADS)

Fedoseev, Gleb; Lamberts, Thanja; Linnartz, Harold; Ioppolo, Sergio; Zhao, Dongfeng

Despite its potential to reveal the link between the formation of simple species and more complex molecules (e.g., amino acids), the nitrogen chemistry of the interstellar medium (ISM) is still poorly understood. Ammonia (NH _{3}) is one of the few nitrogen-bearing species that have been observed in interstellar ices toward young stellar objects (YSOs) and quiescent molecular clouds. The aim of the present work is to experimentally investigate surface formation routes of NH _{3} and HNCO through non-energetic surface reactions in interstellar ice analogues under fully controlled laboratory conditions and at astrochemically relevant cryogenic temperatures. This study focuses on the formation of NH _{3} and HNCO in CO-rich (non-polar) interstellar ices that simulate the CO freeze-out stage in interstellar dark cloud regions, well before thermal and energetic processing start to become predominant. Our work confirms the surface formation of ammonia through the sequential addition of three hydrogen/deuterium atoms to a single nitrogen atom at low temperature. The H/D fractionation of the formed ammonia is also shown. Furthermore, we show the surface formation of solid HNCO through the interaction of CO molecules with NH radicals - one of the intermediates in the formation of solid NH _{3}. Finally, we discuss the implications of HNCO in astrobiology, as a possible starting point for the formation of more complex prebiotic species.

Homologous ligands accommodated by discrete conformations of a buried cavity

PubMed Central

Merski, Matthew; Fischer, Marcus; Balius, Trent E.; Eidam, Oliv; Shoichet, Brian K.

2015-01-01

Conformational change in protein–ligand complexes is widely modeled, but the protein accommodation expected on binding a congeneric series of ligands has received less attention. Given their use in medicinal chemistry, there are surprisingly few substantial series of congeneric ligand complexes in the Protein Data Bank (PDB). Here we determine the structures of eight alkyl benzenes, in single-methylene increases from benzene to n-hexylbenzene, bound to an enclosed cavity in T4 lysozyme. The volume of the apo cavity suffices to accommodate benzene but, even with toluene, larger cavity conformations become observable in the electron density, and over the series two other major conformations are observed. These involve discrete changes in main-chain conformation, expanding the site; few continuous changes in the site are observed. In most structures, two discrete protein conformations are observed simultaneously, and energetic considerations suggest that these conformations are low in energy relative to the ground state. An analysis of 121 lysozyme cavity structures in the PDB finds that these three conformations dominate the previously determined structures, largely modeled in a single conformation. An investigation of the few congeneric series in the PDB suggests that discrete changes are common adaptations to a series of growing ligands. The discrete, but relatively few, conformational states observed here, and their energetic accessibility, may have implications for anticipating protein conformational change in ligand design. PMID:25847998

Homologous ligands accommodated by discrete conformations of a buried cavity.

PubMed

Merski, Matthew; Fischer, Marcus; Balius, Trent E; Eidam, Oliv; Shoichet, Brian K

2015-04-21

Conformational change in protein-ligand complexes is widely modeled, but the protein accommodation expected on binding a congeneric series of ligands has received less attention. Given their use in medicinal chemistry, there are surprisingly few substantial series of congeneric ligand complexes in the Protein Data Bank (PDB). Here we determine the structures of eight alkyl benzenes, in single-methylene increases from benzene to n-hexylbenzene, bound to an enclosed cavity in T4 lysozyme. The volume of the apo cavity suffices to accommodate benzene but, even with toluene, larger cavity conformations become observable in the electron density, and over the series two other major conformations are observed. These involve discrete changes in main-chain conformation, expanding the site; few continuous changes in the site are observed. In most structures, two discrete protein conformations are observed simultaneously, and energetic considerations suggest that these conformations are low in energy relative to the ground state. An analysis of 121 lysozyme cavity structures in the PDB finds that these three conformations dominate the previously determined structures, largely modeled in a single conformation. An investigation of the few congeneric series in the PDB suggests that discrete changes are common adaptations to a series of growing ligands. The discrete, but relatively few, conformational states observed here, and their energetic accessibility, may have implications for anticipating protein conformational change in ligand design.

Examining ion channel properties using free-energy methods.

PubMed

Domene, Carmen; Furini, Simone

2009-01-01

Recent advances in structural biology have revealed the architecture of a number of transmembrane channels, allowing for these complex biological systems to be understood in atomistic detail. Computational simulations are a powerful tool by which the dynamic and energetic properties, and thereby the function of these protein architectures, can be investigated. The experimentally observable properties of a system are often determined more by energetic than dynamics, and therefore understanding the underlying free energy (FE) of biophysical processes is of crucial importance. Critical to the accurate evaluation of FE values are the problems of obtaining accurate sampling of complex biological energy landscapes, and of obtaining accurate representations of the potential energy of a system, this latter problem having been addressed through the development of molecular force fields. While these challenges are common to all FE methods, depending on the system under study, and the questions being asked of it, one technique for FE calculation may be preferable to another, the choice of method and simulation protocol being crucial to achieve efficiency. Applied in a correct manner, FE calculations represent a predictive and affordable computational tool with which to make relevant contact with experiments. This chapter, therefore, aims to give an overview of the most widely implemented computational methods used to calculate the FE associated with particular biochemical or biophysical events, and to highlight their recent applications to ion channels. Copyright © 2009 Elsevier Inc. All rights reserved.

AN IMAGING STUDY OF A COMPLEX SOLAR CORONAL RADIO ERUPTION

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

Feng, S. W.; Chen, Y.; Song, H. Q.

2016-08-10

Solar coronal radio bursts are enhanced radio emission excited by energetic electrons accelerated during solar eruptions. Studying these bursts is important for investigating the origin and physical mechanism of energetic particles and further diagnosing coronal parameters. Earlier studies suffered from a lack of simultaneous high-quality imaging data of the radio burst and the eruptive structure in the inner corona. Here we present a study on a complex solar radio eruption consisting of a type II burst and three reversely drifting type III bursts, using simultaneous EUV and radio imaging data. It is found that the type II burst is closelymore » associated with a propagating and evolving CME-driven EUV shock structure, originated initially at the northern shock flank and later transferred to the top part of the shock. This source transfer is coincident with the presence of shock decay and enhancing signatures observed at the corresponding side of the EUV front. The electron energy accelerated by the shock at the flank is estimated to be ∼0.3 c by examining the imaging data of the fast-drifting herringbone structure of the type II burst. The reverse-drifting type III sources are found to be within the ejecta and correlated with a likely reconnection event therein. The implications for further observational studies and relevant space weather forecasting techniques are discussed.« less

Near-Resonant Thermomechanics of Energetic and Mock Energetic Composite Materials

DTIC Science & Technology

2016-11-01

munition design . 15. SUBJECT TERMS Energetic Materials; Explosives; Mechanical Vibration; Thermomechanics; Damping; Plasticity 16. SECURITY...preliminary computational modeling tools, which can be used to predict material response during energetic material formulation and munition design . Key...which can be used to predict material response during energetic material formulation and munition design . More specifically, Task Order 0001

Rocket measurements of energetic particles in the midlatitude precipitation zone

NASA Technical Reports Server (NTRS)

Voss, H. D.; Smith, L. G.; Braswell, F. M.

1980-01-01

Measurements of energetic ion and electron properties as a function of altitude in the midlatitude zone of nighttime energetic particle precipitation are reported. The measurements of particle fluxes, energy spectra and pitch angle distributions were obtained by a Langmuir probe, six energetic particle spectrometers and an electrostatic analyzer on board a Nike Apache rocket launched near the center of the midlatitude zone during disturbed conditions. It is found that the incident flux was primarily absorbed rather than backscattered, and consists of mainly energetic hydrogen together with some helium and a small energetic electron component. Observed differential energy spectra of protons having an exponential energy spectrum, and pitch angle distributions at various altitudes indicate that the energetic particle flux decreases rapidly for pitch angles less than 70 deg. An energetic particle energy flux of 0.002 ergs/sq cm per sec is calculated which indicates the significance of energetic particles as a primary nighttime ionization source for altitudes between 120 and 200 km in the midlatitude precipitation zone.

Disulfide Trapping for Modeling and Structure Determination of Receptor: Chemokine Complexes.

PubMed

Kufareva, Irina; Gustavsson, Martin; Holden, Lauren G; Qin, Ling; Zheng, Yi; Handel, Tracy M

2016-01-01

Despite the recent breakthrough advances in GPCR crystallography, structure determination of protein-protein complexes involving chemokine receptors and their endogenous chemokine ligands remains challenging. Here, we describe disulfide trapping, a methodology for generating irreversible covalent binary protein complexes from unbound protein partners by introducing two cysteine residues, one per interaction partner, at selected positions within their interaction interface. Disulfide trapping can serve at least two distinct purposes: (i) stabilization of the complex to assist structural studies and/or (ii) determination of pairwise residue proximities to guide molecular modeling. Methods for characterization of disulfide-trapped complexes are described and evaluated in terms of throughput, sensitivity, and specificity toward the most energetically favorable crosslinks. Due to abundance of native disulfide bonds at receptor:chemokine interfaces, disulfide trapping of their complexes can be associated with intramolecular disulfide shuffling and result in misfolding of the component proteins; because of this, evidence from several experiments is typically needed to firmly establish a positive disulfide crosslink. An optimal pipeline that maximizes throughput and minimizes time and costs by early triage of unsuccessful candidate constructs is proposed. © 2016 Elsevier Inc. All rights reserved.

On Complex Nuclei Energetics in LENR

NASA Astrophysics Data System (ADS)

Miley, George H.; Hora, Heinz

2005-03-01

Swimming Electron Layer (SEL) theory plus fission of ``complex nuclei'' were proposed earlier to explain reaction products observed in electrolysis with multi-layer thin-film metallic electrodesootnotetext1.G.H. Miley, and J.A. Patterson, J. New Energy, Vol. 1, pp.11-15, (1996).. SEL was then extended to treat gas-diffusion driven transmutation experimentsootnotetextG. H. Miley and H. Hora, ``Nuclear Reactions in Solids,'' APS DNP Mtg., East Lansing, MI, Oct (2002).. It is also consistent with measured charged-particle emission during thin-film electrolysis and x-ray emission during plasma bombardment experimentsootnotetextA. Karabut, ``X-ray emission in high-current glow discharge,'' Proc., ICCF-9, Beijing China, May (2002).. The binding energy per complex nucleon can be estimated by an energy balance combined with identification of products for each complex e.g. complexes of A 39 have ˜ 0.05 MeV/Nucleon, etc, in thin film electrolysis. Energies in gas diffusion experiments are lower due to the reduced trap site potential at the multi-atom surface. In the case of x-ray emission, complexes involve subsurface defect center traps, giving only a few keV/Nucleon, consistent with experiments^3.

Relational Diversity Promotes Cooperation in Prisoner’s Dilemma Games

PubMed Central

Xu, Bo; Wang, Jianwei; Deng, Ruipu; Li, Miao

2014-01-01

Relational diversity can be characterized by heterogeneous distributions of tie strengths in social networks and this diversity is present not only among humans, but throughout the animal world. We account for this observation by analyzing two network datasets from Facebook. We measure the strength of a tie by calculating the extent of overlap of friends between the two individuals. Based on the previous findings in human experiments, we argue that it is very unlikely that players will allocate their investments equally to their neighbors. There is a tendency that players prefer to donate more to their intimate friends. We find that if players preferentially allocate their investments to their good friends, cooperation will be promoted in PDG. We proved that the facilitation of the cooperative strategy relies mostly on the cooperative allies between best friends, resulting in the formation of cooperative clusters which are able to prevail against the defectors even when there is a large cost to cooperate. Moreover, we discover that the effect of relational diversity cannot be analyzed by adopting classical complex networks models, because neither of the artificial networks is able to produce networks with diverse distributions of tie strengths. It is of vital importance to introduce real social networks to study the influence of diverse relations especially when it comes to humans. This research proposes a brand new perspective to understand the influence of social relations on the emergence of cooperation in evolutionary prisoner’s dilemma games. PMID:25474354

A fast algorithm for identifying friends-of-friends halos

NASA Astrophysics Data System (ADS)

Feng, Y.; Modi, C.

2017-07-01

We describe a simple and fast algorithm for identifying friends-of-friends features and prove its correctness. The algorithm avoids unnecessary expensive neighbor queries, uses minimal memory overhead, and rejects slowdown in high over-density regions. We define our algorithm formally based on pair enumeration, a problem that has been heavily studied in fast 2-point correlation codes and our reference implementation employs a dual KD-tree correlation function code. We construct features in a hierarchical tree structure, and use a splay operation to reduce the average cost of identifying the root of a feature from O [ log L ] to O [ 1 ] (L is the size of a feature) without additional memory costs. This reduces the overall time complexity of merging trees from O [ L log L ] to O [ L ] , reducing the number of operations per splay by orders of magnitude. We next introduce a pruning operation that skips merge operations between two fully self-connected KD-tree nodes. This improves the robustness of the algorithm, reducing the number of merge operations in high density peaks from O [δ2 ] to O [ δ ] . We show that for cosmological data set the algorithm eliminates more than half of merge operations for typically used linking lengths b ∼ 0 . 2 (relative to mean separation). Furthermore, our algorithm is extremely simple and easy to implement on top of an existing pair enumeration code, reusing the optimization effort that has been invested in fast correlation function codes.

Relational diversity promotes cooperation in prisoner's dilemma games.

PubMed

Xu, Bo; Wang, Jianwei; Deng, Ruipu; Li, Miao

2014-01-01

Relational diversity can be characterized by heterogeneous distributions of tie strengths in social networks and this diversity is present not only among humans, but throughout the animal world. We account for this observation by analyzing two network datasets from Facebook. We measure the strength of a tie by calculating the extent of overlap of friends between the two individuals. Based on the previous findings in human experiments, we argue that it is very unlikely that players will allocate their investments equally to their neighbors. There is a tendency that players prefer to donate more to their intimate friends. We find that if players preferentially allocate their investments to their good friends, cooperation will be promoted in PDG. We proved that the facilitation of the cooperative strategy relies mostly on the cooperative allies between best friends, resulting in the formation of cooperative clusters which are able to prevail against the defectors even when there is a large cost to cooperate. Moreover, we discover that the effect of relational diversity cannot be analyzed by adopting classical complex networks models, because neither of the artificial networks is able to produce networks with diverse distributions of tie strengths. It is of vital importance to introduce real social networks to study the influence of diverse relations especially when it comes to humans. This research proposes a brand new perspective to understand the influence of social relations on the emergence of cooperation in evolutionary prisoner's dilemma games.

Colorado Late Cenozoic Fault and Fold Database and Internet Map Server: User-friendly technology for complex information

USGS Publications Warehouse

Morgan, K.S.; Pattyn, G.J.; Morgan, M.L.

2005-01-01

Internet mapping applications for geologic data allow simultaneous data delivery and collection, enabling quick data modification while efficiently supplying the end user with information. Utilizing Web-based technologies, the Colorado Geological Survey's Colorado Late Cenozoic Fault and Fold Database was transformed from a monothematic, nonspatial Microsoft Access database into a complex information set incorporating multiple data sources. The resulting user-friendly format supports easy analysis and browsing. The core of the application is the Microsoft Access database, which contains information compiled from available literature about faults and folds that are known or suspected to have moved during the late Cenozoic. The database contains nonspatial fields such as structure type, age, and rate of movement. Geographic locations of the fault and fold traces were compiled from previous studies at 1:250,000 scale to form a spatial database containing information such as length and strike. Integration of the two databases allowed both spatial and nonspatial information to be presented on the Internet as a single dataset (http://geosurvey.state.co.us/pubs/ceno/). The user-friendly interface enables users to view and query the data in an integrated manner, thus providing multiple ways to locate desired information. Retaining the digital data format also allows continuous data updating and quick delivery of newly acquired information. This dataset is a valuable resource to anyone interested in earthquake hazards and the activity of faults and folds in Colorado. Additional geologic hazard layers and imagery may aid in decision support and hazard evaluation. The up-to-date and customizable maps are invaluable tools for researchers or the public.

Spares Management : Optimizing Hardware Usage for the Space Shuttle Main Engine

NASA Technical Reports Server (NTRS)

Gulbrandsen, K. A.

1999-01-01

The complexity of the Space Shuttle Main Engine (SSME), combined with mounting requirements to reduce operations costs have increased demands for accurate tracking, maintenance, and projections of SSME assets. The SSME Logistics Team is developing an integrated asset management process. This PC-based tool provides a user-friendly asset database for daily decision making, plus a variable-input hardware usage simulation with complex logic yielding output that addresses essential asset management issues. Cycle times on critical tasks are significantly reduced. Associated costs have decreased as asset data quality and decision-making capability has increased.

SABRINA - an interactive geometry modeler for MCNP

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

West, J.T.; Murphy, J.

One of the most difficult tasks when analyzing a complex three-dimensional system with Monte Carlo is geometry model development. SABRINA attempts to make the modeling process more user-friendly and less of an obstacle. It accepts both combinatorial solid bodies and MCNP surfaces and produces MCNP cells. The model development process in SABRINA is highly interactive and gives the user immediate feedback on errors. Users can view their geometry from arbitrary perspectives while the model is under development and interactively find and correct modeling errors. An example of a SABRINA display is shown. It represents a complex three-dimensional shape.

Social closeness and feedback modulate susceptibility to the framing effect.

PubMed

Sip, Kamila E; Smith, David V; Porcelli, Anthony J; Kar, Kohitij; Delgado, Mauricio R

2015-01-01

Although we often seek social feedback (SFB) from others to help us make decisions, little is known about how SFB affects decisions under risk, particularly from a close peer. We conducted two experiments using an established framing task to probe how decision-making is modulated by SFB valence (positive, negative) and the level of closeness with feedback provider (friend, confederate). Participants faced mathematically equivalent decisions framed as either an opportunity to keep (gain frame) or lose (loss frame) part of an initial endowment. Periodically, participants were provided with positive (e.g., "Nice!") or negative (e.g., "Lame!") feedback about their choices. Such feedback was provided by either a confederate (Experiment 1) or a gender-matched close friend (Experiment 2). As expected, the framing effect was observed in both experiments. Critically, an individual's susceptibility to the framing effect was modulated by the valence of the SFB, but only when the feedback provider was a close friend. This effect was reflected in the activation patterns of ventromedial prefrontal cortex and posterior cingulate cortex, regions involved in complex decision-making. Taken together, these results highlight social closeness as an important factor in understanding the impact of SFB on neural mechanisms of decision-making.

Hyperbranched exopolysaccharide-enhanced foam properties of sodium fatty alcohol polyoxyethylene ether sulfate.

PubMed

Deng, Quanhua; Li, Haiping; Sun, Haoyang; Sun, Yange; Li, Ying

2016-05-01

The foam properties, such as the foamability, foam stability, drainage, coalescence and bulk rheology, of aqueous solutions containing an eco-friendly exopolysaccharide (EPS) secreted by a deep-sea mesophilic bacterium, Wangia profunda SM-A87, and an anionic surfactant, sodium fatty alcohol polyoxyethylene ether sulfate (AES), were studied. Both the foamability and foam stability of the EPS/AES solutions are considerably higher than those of single AES solutions, even at very low AES concentrations, although pure EPS solutions cannot foam. The improved foamability and foam stability arise from the formation of the EPS/AES complex via hydrogen bonds at the interfaces. The synergism between the EPS and AES decreases the surface tension, increases the interfacial elasticity and water-carrying capacity, and suppresses the coalescence and collapse of the foams. The EPS/AES foams are more salt-resistant than the AES foams. This work provides not only a new eco-friendly foam with great potential for use in enhanced oil recovery and health-care products but also useful guidance for designing other environmentally friendly foam systems that exhibit high performance. Copyright © 2016 Elsevier B.V. All rights reserved.

Individual Psychological Factors and Complex Interpersonal Conditions that Predict LGBT-Affirming Behavior.

PubMed

Poteat, V Paul

2015-08-01

To counter homophobic behavior in schools, research is needed on heterosexual youth who act as allies to lesbian, gay, bisexual, and transgender (LGBT) youth by engaging in LGBT-affirming behavior (e.g., voicing support, engaging in advocacy, countering homophobia). Among 624 heterosexual high school students (M age = 16.11; 53 % female; 88 % white), this study found that critical thinking, self-reflection, lower sexual prejudice, having more LGBT friends, and having sexual orientation-based discussions with peers were associated with engaging in more LGBT-affirming behavior. Several factors moderated the association between having sexual orientation-based discussions and LGBT-affirming behavior: the association was stronger among youth who described the tone of these discussions as more positive, who more often used positive problem-solving strategies, and who reported low sexual prejudice. The degree to which conversations were challenging did not moderate this association. Finally, having LGBT friends was more strongly associated with affirming behavior for youth who felt more connected and had more sexual orientation-based discussions with these friends. The findings underscore the need for research to identify other factors that prompt heterosexual youth to act as allies to LGBT youth.

Observation of enhanced radial transport of energetic ion due to energetic particle mode destabilized by helically-trapped energetic ion in the Large Helical Device

NASA Astrophysics Data System (ADS)

Ogawa, K.; Isobe, M.; Kawase, H.; Nishitani, T.; Seki, R.; Osakabe, M.; LHD Experiment Group

2018-04-01

A deuterium experiment was initiated to achieve higher-temperature and higher-density plasmas in March 2017 in the Large Helical Device (LHD). The central ion temperature notably increases compared with that in hydrogen experiments. However, an energetic particle mode called the helically-trapped energetic-ion-driven resistive interchange (EIC) mode is often excited by intensive perpendicular neutral beam injections on high ion-temperature discharges. The mode leads to significant decrease of the ion temperature or to limiting the sustainment of the high ion-temperature state. To understand the effect of EIC on the energetic ion confinement, the radial transport of energetic ions is studied by means of the neutron flux monitor and vertical neutron camera newly installed on the LHD. Decreases of the line-integrated neutron profile in core channels show that helically-trapped energetic ions are lost from the plasma.

Does Helping Keep Teens Protected? Longitudinal Bidirectional Relations Between Prosocial Behavior and Problem Behavior.

PubMed

Padilla-Walker, Laura M; Carlo, Gustavo; Nielson, Matthew G

2015-01-01

The current study examined bidirectional, longitudinal links between prosocial and problem behavior. Participants (N = 500) were recruited from a Northwestern city in the United States and assessed for 3 consecutive years from 2009 to 2011 (M(age) of youth at Time 1 = 13.32, SD = 1.05; 52% girls; 67% European American, 33% single-parent families). Results suggested that effects of earlier prosocial behavior toward family and strangers were predictive of fewer problem behaviors 2 years later, while results for prosocial behavior toward friends were more mixed. Results also suggested depression predicted lower prosocial behavior toward family members and anxiety predicted higher prosocial behavior toward friends. Findings show a complex pattern of relations that demonstrate the need to consider targets of helping. © 2015 The Authors. Child Development © 2015 Society for Research in Child Development, Inc.

The simple rules of social contagion.

PubMed

Hodas, Nathan O; Lerman, Kristina

2014-03-11

It is commonly believed that information spreads between individuals like a pathogen, with each exposure by an informed friend potentially resulting in a naive individual becoming infected. However, empirical studies of social media suggest that individual response to repeated exposure to information is far more complex. As a proxy for intervention experiments, we compare user responses to multiple exposures on two different social media sites, Twitter and Digg. We show that the position of exposing messages on the user-interface strongly affects social contagion. Accounting for this visibility significantly simplifies the dynamics of social contagion. The likelihood an individual will spread information increases monotonically with exposure, while explicit feedback about how many friends have previously spread it increases the likelihood of a response. We provide a framework for unifying information visibility, divided attention, and explicit social feedback to predict the temporal dynamics of user behavior.

The Simple Rules of Social Contagion

NASA Astrophysics Data System (ADS)

Hodas, Nathan O.; Lerman, Kristina

2014-03-01

It is commonly believed that information spreads between individuals like a pathogen, with each exposure by an informed friend potentially resulting in a naive individual becoming infected. However, empirical studies of social media suggest that individual response to repeated exposure to information is far more complex. As a proxy for intervention experiments, we compare user responses to multiple exposures on two different social media sites, Twitter and Digg. We show that the position of exposing messages on the user-interface strongly affects social contagion. Accounting for this visibility significantly simplifies the dynamics of social contagion. The likelihood an individual will spread information increases monotonically with exposure, while explicit feedback about how many friends have previously spread it increases the likelihood of a response. We provide a framework for unifying information visibility, divided attention, and explicit social feedback to predict the temporal dynamics of user behavior.

CTX-M-15-non-ST131 Escherichia coli isolates are mainly responsible of faecal carriage with ESBL-producing Enterobacteriaceae in travellers, immigrants and those visiting friends and relatives.

PubMed

Valverde, A; Turrientes, M-C; Norman, F; San Martín, E; Moreno, L; Pérez-Molina, J A; López-Vélez, R; Cantón, R

2015-03-01

Prevalence of extended-spectrum β-lactamases (ESBL) and/or carbapenemase-producing Enterobacteriaceae (EPE and CPE) in stool samples from 75 travellers, 8 people visiting friends and relatives and 3 immigrants who had travelled or came from tropical or subtropical areas was determined. Thirty-one per cent (27/86) of the subjects were faecal carriers of EPE, and 37 EPE isolates were recovered (36 Escherichia coli, 1 Klebsiella pneumoniae). CTX-M-15 was the most prevalent enzyme (64.8%) mainly associated with E. coli belonging to phylogroup A and sequence type complex 10. Most of the ESBL-positive travellers (50%) had visited countries from Asia. Copyright © 2014 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Decrypting the structural, dynamic, and energetic basis of a monomeric kinesin interacting with a tubulin dimer in three ATPase states by all-atom molecular dynamics simulation.

PubMed

Chakraborty, Srirupa; Zheng, Wenjun

2015-01-27

We have employed molecular dynamics (MD) simulation to investigate, with atomic details, the structural dynamics and energetics of three major ATPase states (ADP, APO, and ATP state) of a human kinesin-1 monomer in complex with a tubulin dimer. Starting from a recently solved crystal structure of ATP-like kinesin-tubulin complex by the Knossow lab, we have used flexible fitting of cryo-electron-microscopy maps to construct new structural models of the kinesin-tubulin complex in APO and ATP state, and then conducted extensive MD simulations (total 400 ns for each state), followed by flexibility analysis, principal component analysis, hydrogen bond analysis, and binding free energy analysis. Our modeling and simulation have revealed key nucleotide-dependent changes in the structure and flexibility of the nucleotide-binding pocket (featuring a highly flexible and open switch I in APO state) and the tubulin-binding site, and allosterically coupled motions driving the APO to ATP transition. In addition, our binding free energy analysis has identified a set of key residues involved in kinesin-tubulin binding. On the basis of our simulation, we have attempted to address several outstanding issues in kinesin study, including the possible roles of β-sheet twist and neck linker docking in regulating nucleotide release and binding, the structural mechanism of ADP release, and possible extension and shortening of α4 helix during the ATPase cycle. This study has provided a comprehensive structural and dynamic picture of kinesin's major ATPase states, and offered promising targets for future mutational and functional studies to investigate the molecular mechanism of kinesin motors.

Metastable electronic states in uranium tetrafluoride

DOE PAGES

Miskowiec, Andrew J.

2018-04-03

Here, the DFT+ U approach, where U is the Hubbard-like on-site Coulomb interaction, has successfully been used to improve the description of transition metal oxides and other highly correlated systems, including actinides. The secret of the DFT+ U approach is the breaking of d or f shell orbital degeneracy and adding an additional energetic penalty to non-integer occupation of orbitals. A prototypical test case, UO 2, benefits from the + U approach whereby the bare LDA method predicts UO 2 to be a ferromagnetic metal, whereas LDA+ U correctly predicts UO 2 to be insulating. However, the concavity of themore » energetic penalty in the DFT+ U approach can lead to a number of convergent “metastable” electronic configurations residing above the ground state. Uranium tetrafluoride (UF 4) represents a more complex analogy to UO 2 in that the crystal field has lower symmetry and the unit cell contains two symmetrically distinct U atoms. We explore the metastable states in UF 4 using several different methods of selecting initial orbital occupations. Two methods, a “pre-relaxation” method wherein an initial set of orbital eigenvectors is selected via the self-consistency procedure and a crystal rotation method wherein the x, y, z axes are brought into alignment with the crystal field, are explored. We show that in the case of UF 4, which has non-collinearity between its crystal axes and the U atoms' crystal field potentials, the orbital occupation matrices are much more complex and should be analyzed using a novel approach. In addition to demonstrating a complex landscape of metastable electronic states, UF 4 also shows significant hybridization in U–F bonding, which involves non-trivial contributions from s, p, d, and f orbitals.« less

Effect of chronic pre-treatment with angiotensin converting enzyme inhibition on skeletal muscle mitochondrial recovery after ischemia/reperfusion.

PubMed

Thaveau, Fabien; Zoll, Joffrey; Bouitbir, Jamal; N'guessan, Benoît; Plobner, Philippe; Chakfe, Nabil; Kretz, Jean-Georges; Richard, Ruddy; Piquard, François; Geny, Bernard

2010-06-01

Impaired skeletal muscle energetic participates in peripheral arterial disease (PAD) patient's morbidity and mortality. Angiotensin converting enzyme inhibition (ACEi), cornerstone for pharmacologic risk factor management in PAD patients, might also be interesting by protecting skeletal muscle energetic. We therefore determined whether chronic ACEi might reduce ischemia-induced mitochondrial respiratory chain dysfunction in the frequent setting of hindlimb ischemia-reperfusion. Ischemic legs of rats submitted to 5 h ischemia induced by a rubber band tourniquet applied on the root of the hindlimb followed by reperfusion without (IR, n = 11) or after ACEi (n = 14; captopril 40 mg/kg per day during 28 days before surgery) were studied and compared to that of sham-operated animals (n = 11). The effect of ACEi on the non-ischemic contralateral leg was also determined in the ACEi group. Maximal oxidative capacities (V(max)) and complexes I, II and IV activities of the mitochondrial respiratory chain of the gastrocnemius muscle were determined using glutamate-malate, succinate and TMPD-ascorbate substrates. Arterial blood pressure was significantly decreased after ACEi (124 +/- 2.8 vs. 108 +/- 4.19 mmHg; P = 0.01). Ischemia-reperfusion reduced V(max) (4.4 +/- 0.4 vs. 8.7 +/- 0.5 micromol O2/min/g dry weight, -49%, P < 0.001), affecting mitochondrial complexes I, II and IV activities. ACEi failed to modulate ischemia-induced dysfunction (V(max) 5.1 +/- 0.7 micromol O2/min/g dry weight) or the non-ischemic contralateral muscle respiratory rate. Ischemia-reperfusion significantly impaired the mitochondrial respiratory chain I, II and IV complexes of skeletal muscle. Pharmacologic pre-treatment with ACEi did not prevent or increase such alterations. Further studies might be useful to improve the pharmacologic conditioning of PAD patients needing arterial revascularization.

Activation of carbon-hydrogen bonds via 1,2-addition across M-X (X = OH or NH(2)) bonds of d(6) transition metals as a potential key step in hydrocarbon functionalization: a computational study.

PubMed

Cundari, Thomas R; Grimes, Thomas V; Gunnoe, T Brent

2007-10-31

Recent reports of 1,2-addition of C-H bonds across Ru-X (X = amido, hydroxo) bonds of TpRu(PMe3)X fragments {Tp = hydridotris(pyrazolyl)borate} suggest opportunities for the development of new catalytic cycles for hydrocarbon functionalization. In order to enhance understanding of these transformations, computational examinations of the efficacy of model d6 transition metal complexes of the form [(Tab)M(PH3)2X]q (Tab = tris-azo-borate; X = OH, NH2; q = -1 to +2; M = TcI, Re(I), Ru(II), Co(III), Ir(III), Ni(IV), Pt(IV)) for the activation of benzene C-H bonds, as well as the potential for their incorporation into catalytic functionalization cycles, are presented. For the benzene C-H activation reaction steps, kite-shaped transition states were located and found to have relatively little metal-hydrogen interaction. The C-H activation process is best described as a metal-mediated proton transfer in which the metal center and ligand X function as an activating electrophile and intramolecular base, respectively. While the metal plays a primary role in controlling the kinetics and thermodynamics of the reaction coordinate for C-H activation/functionalization, the ligand X also influences the energetics. On the basis of three thermodynamic criteria characterizing salient energetic aspects of the proposed catalytic cycle and the detailed computational studies reported herein, late transition metal complexes (e.g., Pt, Co, etc.) in the d6 electron configuration {especially the TabCo(PH3)2(OH)+ complex and related Co(III) systems} are predicted to be the most promising for further catalyst investigation.

Metastable electronic states in uranium tetrafluoride

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

Miskowiec, Andrew J.

Here, the DFT+ U approach, where U is the Hubbard-like on-site Coulomb interaction, has successfully been used to improve the description of transition metal oxides and other highly correlated systems, including actinides. The secret of the DFT+ U approach is the breaking of d or f shell orbital degeneracy and adding an additional energetic penalty to non-integer occupation of orbitals. A prototypical test case, UO 2, benefits from the + U approach whereby the bare LDA method predicts UO 2 to be a ferromagnetic metal, whereas LDA+ U correctly predicts UO 2 to be insulating. However, the concavity of themore » energetic penalty in the DFT+ U approach can lead to a number of convergent “metastable” electronic configurations residing above the ground state. Uranium tetrafluoride (UF 4) represents a more complex analogy to UO 2 in that the crystal field has lower symmetry and the unit cell contains two symmetrically distinct U atoms. We explore the metastable states in UF 4 using several different methods of selecting initial orbital occupations. Two methods, a “pre-relaxation” method wherein an initial set of orbital eigenvectors is selected via the self-consistency procedure and a crystal rotation method wherein the x, y, z axes are brought into alignment with the crystal field, are explored. We show that in the case of UF 4, which has non-collinearity between its crystal axes and the U atoms' crystal field potentials, the orbital occupation matrices are much more complex and should be analyzed using a novel approach. In addition to demonstrating a complex landscape of metastable electronic states, UF 4 also shows significant hybridization in U–F bonding, which involves non-trivial contributions from s, p, d, and f orbitals.« less

Structured analysis and modeling of complex systems

NASA Technical Reports Server (NTRS)

Strome, David R.; Dalrymple, Mathieu A.

1992-01-01

The Aircrew Evaluation Sustained Operations Performance (AESOP) facility at Brooks AFB, Texas, combines the realism of an operational environment with the control of a research laboratory. In recent studies we collected extensive data from the Airborne Warning and Control Systems (AWACS) Weapons Directors subjected to high and low workload Defensive Counter Air Scenarios. A critical and complex task in this environment involves committing a friendly fighter against a hostile fighter. Structured Analysis and Design techniques and computer modeling systems were applied to this task as tools for analyzing subject performance and workload. This technology is being transferred to the Man-Systems Division of NASA Johnson Space Center for application to complex mission related tasks, such as manipulating the Shuttle grappler arm.

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

Li, Y; Liu, B; Liang, B

Purpose: Current CyberKnife treatment planning system (TPS) provided two dose calculation algorithms: Ray-tracing and Monte Carlo. Ray-tracing algorithm is fast, but less accurate, and also can’t handle irregular fields since a multi-leaf collimator system was recently introduced to CyberKnife M6 system. Monte Carlo method has well-known accuracy, but the current version still takes a long time to finish dose calculations. The purpose of this paper is to develop a GPU-based fast C/S dose engine for CyberKnife system to achieve both accuracy and efficiency. Methods: The TERMA distribution from a poly-energetic source was calculated based on beam’s eye view coordinate system,more » which is GPU friendly and has linear complexity. The dose distribution was then computed by inversely collecting the energy depositions from all TERMA points along 192 collapsed-cone directions. EGSnrc user code was used to pre-calculate energy deposition kernels (EDKs) for a series of mono-energy photons The energy spectrum was reconstructed based on measured tissue maximum ratio (TMR) curve, the TERMA averaged cumulative kernels was then calculated. Beam hardening parameters and intensity profiles were optimized based on measurement data from CyberKnife system. Results: The difference between measured and calculated TMR are less than 1% for all collimators except in the build-up regions. The calculated profiles also showed good agreements with the measured doses within 1% except in the penumbra regions. The developed C/S dose engine was also used to evaluate four clinical CyberKnife treatment plans, the results showed a better dose calculation accuracy than Ray-tracing algorithm compared with Monte Carlo method for heterogeneous cases. For the dose calculation time, it takes about several seconds for one beam depends on collimator size and dose calculation grids. Conclusion: A GPU-based C/S dose engine has been developed for CyberKnife system, which was proven to be efficient and accurate for clinical purpose, and can be easily implemented in TPS.« less

Earth Day 2018 Activities

NASA Image and Video Library

2018-04-17

During the annual Earth Day celebration at the Kennedy Space Center Visitor Complex, guests have an opportunity to get an up-close look at experimental electric vehicles. The "Remove Before Flight" tag is on a Polaris GEM electric car. The two-day event featured approximately 50 exhibitors offering information on a variety of topics, including electric vehicles, sustainable lighting, renewable energy, Florida-friendly landscaping tips, Florida’s biking trails and more.

Discrete Conformal Approximation of Complex Earthquake Maps

DTIC Science & Technology

2005-08-01

Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503. 1. AGENCY USE ONLY...ing when my dreams were not yours. Thank you for teaching me that books are my friends (though I may have taken that a little too much to heart), and...61 4.2 Hyperbolic Projections ....... ...................... 63 4.3 Discrete Shearing Maps ............................. 64

Wound Healing in Mac-1 Deficient Mice

DTIC Science & Technology

2017-05-01

36. Rosenkranz AR, Coxon A, Maurer M, Gurish MF, Austen KF, Friend DS, Galli SJ, Mayadas TN. Impaired mast cell development and innate immunity in Mac...genetically deficient mice. 3 INTRODUCTION Wound healing is a complex yet well-regulated process in which multiple resident cells ...recruited inflammatory cells , and stem cells interact to create an environment that supports the healing process. An optimal inflammatory response is a

What's working on working rivers: a handbook for improving urban rivers: examples from Chicago area rivers.

Treesearch

Naomi Cohn

1998-01-01

What's been done on Chicago Area Rivers is truly an inspiration. People's ability to improve these rivers shows what can be improved anywhere, even in a highly developed and complex urban setting like Chicago. A veteran staffer with the Friends of the Chicago River recently concluded: "People look at what's being accomplished on the Chicago River...

Let's Plan the School Garden: A Participatory Project on Sustainability in a Nursery School in Padua

ERIC Educational Resources Information Center

Rocca, Lorena; Donadelli, Giovanni; Ziliotto, Sonia

2012-01-01

The increasing complexity of urban regions and the lack of green areas in the neighborhoods have turned the cities less and less child-friendly. In order to locally face these situations, the project "Small steps of Agenda 21," which promoted a participatory planning experience for children focused on the green area of their school, was…

Rural Australian Women's Legal Help Seeking for Intimate Partner Violence: Women Intimate Partner Violence Victim Survivors' Perceptions of Criminal Justice Support Services

ERIC Educational Resources Information Center

Ragusa, Angela T.

2013-01-01

Intimate partner violence (IPV) is a widespread, ongoing, and complex global social problem, whose victims continue to be largely women. Women often prefer to rely on friends and family for IPV help, yet when informal support is unavailable they remain hesitant to contact formal services, particularly legal support for many reasons. This study…

Telerobot operator control station requirements

NASA Technical Reports Server (NTRS)

Kan, Edwin P.

1988-01-01

The operator control station of a telerobot system has unique functional and human factors requirements. It has to satisfy the needs of a truly interactive and user-friendly complex system, a telerobot system being a hybrid between a teleoperated and an autonomous system. These functional, hardware and software requirements are discussed, with explicit reference to the design objectives and constraints of the JPL/NASA Telerobot Demonstrator System.

Modeling the Role of Bulk and Surface Characteristics of Carbon Fiber on Thermal Conductance across the Carbon Fiber/Matrix Interface (Postprint)

DTIC Science & Technology

2015-11-09

Osguthorpe, D. J.; Wolff, J.; Genest, M.; Hagler, A. T. Structure and Energetics of Ligand Binding to Proteins: Escherichia Coli Dihydrofolate...available at DOI: 10.1021/acsami.5b08591 14. ABSTRACT (Maximum 200 words) The rapid heating of carbon-fiber-reinforced polymer matrix composites leads ...polymer matrix composites leads to complex thermophysical interactions which not only are dependent on the thermal properties of the constituents and

The Hinge Region as a Key Regulatory Element of Androgen Receptor Dimerization, DNA Binding and Transactivation

DTIC Science & Technology

2006-05-01

Mutations in the human androgen receptor gene as a learning tool for molecular endocrinology’ III. Poster presentations at international meetings...nonconsensus half-site, the cognate half-complex buries slightly more surface area from solvent (1,230 Å2) than the noncognate one (960 Å2). AR Mutations ...energetic penalty in- Fig. 4. (A) The AR DBD dimer interface. The molecular surfaces of the AR subunits are shown in red and blue. Dashed black lines

Energetic Ionic Liquids Based on Lanthanide Nitrate Complex Anions (Postprint)

DTIC Science & Technology

2008-01-01

calculated nitrogen content for CO-balanced aluminum -con- taining ionic liquids is 28%,[3] while the nitrogen content of CO-balanced salts 11 and 12 is...1 mg of 11 was heated to 200 8C in a micro melting point apparatus, gases rapidly evolved to leave white lanthanum oxide powder . The decomposition...Iyen- gar , J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J

Spectrophotometry of stars 9 - 12m north polar spectrophotometric sequence (NPSS) program.

NASA Astrophysics Data System (ADS)

Sharipova, L. M.; Prokof'eva, V. V.

Spectrophotometric observations of stars 9 - 12m of the NPSS program have been made with the use of hgh-sensitivity light-detecting apparatus of the digital television complex of the 0.5-m Maksutov telescope MTM-500 and original slitless spectrograph. Atmospheric extinction was controlled during the night by means of an energetically calibrated brightness standard. Absolute energy distributions of 12 stars, their synthetic magnitudes in the V band, and B-V color indices were obtained.

Six new complexes constructed from silver(I) and 2-(dinitromethylene)-1,3-diazacyclopentane (DNDZ): Synthesis, crystal structure and properties

NASA Astrophysics Data System (ADS)

Feng, Zhicun; Zhang, Hang; Xu, Kangzhen; Song, Jirong; Zhao, Fengqi

2018-04-01

Six different energetic silver complexes of 2-(dinitromethylene)-1,3-diazacyclopentane (DNDZ), Ag(DNDZ) (1), [Ag2(H2O)(DNDZ)]n (2), Ag(NH3)DNDZ (3), Ag(CH3NH2)(DNDZ) (4), Ag(C2H5NH2)(DNDZ) (5) and Ag(C3H7NH2)(DNDZ) (6), were first synthesized and structurally characterized. Complexes 2, 3, 5 and 6 were characterized by the single crystal X-ray diffraction analysis. Complexes 2, 5 and 6 crystallize in the monoclinic crystal system with space group P21/n containing four molecules per unit cell, but the crystal of complex 3 is triclinic with space group P-1 containing two molecules in each unit cell. Complexes 2 and 3 possess Ag⋯Ag interaction and corresponding central symmetric structure, but complexes 5 and 6 do not. Thermal behaviors of complexes 1-6 were determined and analyzed. The order of thermal stability for the six complexes is 4 > 3 >1 > 2 >5 > 6. Impact sensitivities for complexes 1-6 are >12 J, > 4 J, > 13 J, > 16 J, > 8 J and >7 J respectively, which corresponds well to the results of thermal stability for the six complexes except for complex 2. Moreover, natural bond orbital (NBO) analysis was used to investigate the bonding and hybridization of complex 3.

Complex Quantum Network Manifolds in Dimension d > 2 are Scale-Free

PubMed Central

Bianconi, Ginestra; Rahmede, Christoph

2015-01-01

In quantum gravity, several approaches have been proposed until now for the quantum description of discrete geometries. These theoretical frameworks include loop quantum gravity, causal dynamical triangulations, causal sets, quantum graphity, and energetic spin networks. Most of these approaches describe discrete spaces as homogeneous network manifolds. Here we define Complex Quantum Network Manifolds (CQNM) describing the evolution of quantum network states, and constructed from growing simplicial complexes of dimension . We show that in d = 2 CQNM are homogeneous networks while for d > 2 they are scale-free i.e. they are characterized by large inhomogeneities of degrees like most complex networks. From the self-organized evolution of CQNM quantum statistics emerge spontaneously. Here we define the generalized degrees associated with the -faces of the -dimensional CQNMs, and we show that the statistics of these generalized degrees can either follow Fermi-Dirac, Boltzmann or Bose-Einstein distributions depending on the dimension of the -faces. PMID:26356079

Lewis acid-base interactions in weakly bound formaldehyde complexes with CO2, HCN, and FCN: considerations on the cooperative H-bonding effects.

PubMed

Rivelino, Roberto

2008-01-17

Ab initio quantum chemistry calculations reveal that HCN and mainly FCN can form Lewis acid-base complexes with formaldehyde associated with cooperative H bonds, as first noticed by Wallen et al. (Blatchford, M. A.; Raveendran, P.; Wallen, S. L. J. Am. Chem. Soc. 2002, 124, 14818-14819) for CO2-philic materials under supercritical conditions. The present results, obtained with MP2(Full)/aug-cc-pVDZ calculations, show that the degeneracy of the nu(2) mode in free HCN or FCN is removed upon complexation in the same fashion as that of CO2. The splitting of these bands along with the electron structure analysis provides substantial evidence of the interaction of electron lone pairs of the carbonyl oxygen with the electron-deficient carbon atom of the cyanides. Also, this work investigates the role of H bonds acting as additional stabilizing interactions in the complexes by performing the energetic and geometric characterization.

A surprising role for conformational entropy in protein function

PubMed Central

Wand, A. Joshua; Moorman, Veronica R.; Harpole, Kyle W.

2014-01-01

Formation of high-affinity complexes is critical for the majority of enzymatic reactions involving proteins. The creation of the family of Michaelis and other intermediate complexes during catalysis clearly involves a complicated manifold of interactions that are diverse and complex. Indeed, computing the energetics of interactions between proteins and small molecule ligands using molecular structure alone remains a grand challenge. One of the most difficult contributions to the free energy of protein-ligand complexes to experimentally access is that due to changes in protein conformational entropy. Fortunately, recent advances in solution nuclear magnetic resonance (NMR) relaxation methods have enabled the use of measures-of-motion between conformational states of a protein as a proxy for conformational entropy. This review briefly summarizes the experimental approaches currently employed to characterize fast internal motion in proteins, how this information is used to gain insight into conformational entropy, what has been learned and what the future may hold for this emerging view of protein function. PMID:23478875

Complex Quantum Network Manifolds in Dimension d > 2 are Scale-Free.

PubMed

Bianconi, Ginestra; Rahmede, Christoph

2015-09-10

In quantum gravity, several approaches have been proposed until now for the quantum description of discrete geometries. These theoretical frameworks include loop quantum gravity, causal dynamical triangulations, causal sets, quantum graphity, and energetic spin networks. Most of these approaches describe discrete spaces as homogeneous network manifolds. Here we define Complex Quantum Network Manifolds (CQNM) describing the evolution of quantum network states, and constructed from growing simplicial complexes of dimension d. We show that in d = 2 CQNM are homogeneous networks while for d > 2 they are scale-free i.e. they are characterized by large inhomogeneities of degrees like most complex networks. From the self-organized evolution of CQNM quantum statistics emerge spontaneously. Here we define the generalized degrees associated with the δ-faces of the d-dimensional CQNMs, and we show that the statistics of these generalized degrees can either follow Fermi-Dirac, Boltzmann or Bose-Einstein distributions depending on the dimension of the δ-faces.

Molecular dynamics study of thermodynamic stability and dynamics of [Li(glyme)]+ complex in lithium-glyme solvate ionic liquids

NASA Astrophysics Data System (ADS)

Shinoda, Wataru; Hatanaka, Yuta; Hirakawa, Masashi; Okazaki, Susumu; Tsuzuki, Seiji; Ueno, Kazuhide; Watanabe, Masayoshi

2018-05-01

Equimolar mixtures of glymes and organic lithium salts are known to produce solvate ionic liquids, in which the stability of the [Li(glyme)]+ complex plays an important role in determining the ionic dynamics. Since these mixtures have attractive physicochemical properties for application as electrolytes, it is important to understand the dependence of the stability of the [Li(glyme)]+ complex on the ion dynamics. A series of microsecond molecular dynamics simulations has been conducted to investigate the dynamic properties of these solvate ionic liquids. Successful solvate ionic liquids with high stability of the [Li(glyme)]+ complex have been shown to have enhanced ion dynamics. Li-glyme pair exchange rarely occurs: its characteristic time is longer than that of ion diffusion by one or two orders of magnitude. Li-glyme pair exchange most likely occurs through cluster formation involving multiple [Li(glyme)]+ pairs. In this process, multiple exchanges likely take place in a concerted manner without the production of energetically unfavorable free glyme or free Li+ ions.

Bioengineering strategies to generate artificial protein complexes.

PubMed

Kim, Heejae; Siu, Ka-Hei; Raeeszadeh-Sarmazdeh, Maryam; Sun, Qing; Chen, Qi; Chen, Wilfred

2015-08-01

For many applications, increasing synergy between distinct proteins through organization is important for the specificity, regulation, and overall reaction efficiency. Although there are many examples of protein complexes in nature, a generalized method to create these complexes remains elusive. Many conventional techniques such as random chemical conjugation, physical adsorption onto surfaces, and encapsulation within matrices are imprecise approaches and can lead to deactivation of protein native functionalities. More "bio-friendly" approaches such as genetically fused proteins and biological scaffolds often can result in low yields and low complex stability. Alternatively, site-specific protein conjugation or ligation can generate artificial protein complexes that preserve the native functionalities of protein domains and maintain stability through covalent bonds. In this review, we describe three distinct methods to synthesize artificial protein complexes (genetic incorPoration of unnatural amino acids to introduce bio-orthogonal azide and alkyne groups to proteins, split-intein based expressed protein ligation, and sortase mediated ligation) and highlight interesting applications for each technique. © 2015 Wiley Periodicals, Inc.

Complexes of oligo(poly)nucleotides with structural anomalies

NASA Astrophysics Data System (ADS)

Dolinnaya, N. G.; Gryaznova, O. I.

1989-08-01

The results of studies on the structure and properties of DNA-RNA hybrids and complexes of oligo(poly)nucleotides containing non-canonical base pairs or unpaired bases both within and at the ends of the double helix are surveyed. The methods used in the study of such systems are briefly characterised: X-ray diffraction analysis, NMR and UV spectroscopy, circular dichroism, scanning microcalorimetry, etc. A comparative analysis of the influence of the non-canonical pairs on the structure and the energetic and kinetic parameters of the formation and dissociation of the oligonucleotide complexes has been carried out. The question of the stability of the non-canonical pairs as a function of their nature and position in the double helix is considered. The mechanisms of the formation of the hydrogen bonds between the bases of non-complementary pairs are discussed. The bibliography includes 171 references.

Direct observation of bis(dicarbollyl)nickel conformers in solution by fluorescence spectroscopy: an approach to redox-controlled metallacarborane molecular motors.

PubMed

Safronov, Alexander V; Shlyakhtina, Natalia I; Everett, Thomas A; VanGordon, Monika R; Sevryugina, Yulia V; Jalisatgi, Satish S; Hawthorne, M Frederick

2014-10-06

As a continuation of work on metallacarborane-based molecular motors, the structures of substituted bis(dicarbollyl)nickel complexes in Ni(III) and Ni(IV) oxidation states were investigated in solution by fluorescence spectroscopy. Symmetrically positioned cage-linked pyrene molecules served as fluorescent probes to enable the observation of mixed meso-trans/dl-gauche (pyrene monomer fluorescence) and dl-cis/dl-gauche (intramolecular pyrene excimer fluorescence with residual monomer fluorescence) cage conformations of the nickelacarboranes in the Ni(III) and Ni(IV) oxidation states, respectively. The absence of energetically disfavored conformers in solution--dl-cis in the case of nickel(III) complexes and meso-trans in the case of nickel(IV)--was demonstrated based on spectroscopic data and conformer energy calculations in solution. The conformational persistence observed in solution indicates that bis(dicarbollyl)nickel complexes may provide attractive templates for building electrically driven and/or photodriven molecular motors.

A spin-frustrated trinuclear copper complex based on triaminoguanidine with an energetically well-separated degenerate ground state.

PubMed

Spielberg, Eike T; Gilb, Aksana; Plaul, Daniel; Geibig, Daniel; Hornig, David; Schuch, Dirk; Buchholz, Axel; Ardavan, Arzhang; Plass, Winfried

2015-04-06

We present the synthesis and crystal structure of the trinuclear copper complex [Cu3(saltag)(bpy)3]ClO4·3DMF [H5saltag = tris(2-hydroxybenzylidene)triaminoguanidine; bpy = 2,2'-bipyridine]. The complex crystallizes in the trigonal space group R3̅, with all copper ions being crystallographically equivalent. Analysis of the temperature dependence of the magnetic susceptibility shows that the triaminoguanidine ligand mediates very strong antiferromagnetic interactions (JCuCu = -324 cm(-1)). Detailed analysis of the magnetic susceptibility and magnetization data as well as X-band electron spin resonance spectra, all recorded on both powdered samples and single crystals, show indications of neither antisymmetric exchange nor symmetry lowering, thus indicating only a very small splitting of the degenerate S = (1)/2 ground state. These findings are corroborated by density functional theory calculations, which explain both the strong isotropic and negligible antisymmetric exchange interactions.

Roles of Acetone and Diacetone Alcohol in Coordination and Dissociation Reactions of Uranyl Complexes

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

Rios, Daniel; Schoendorff, George E.; Van Stipdonk, Michael J.

2012-12-03

Combined collision-induced dissociation mass-spectrometry experiments and DFT calculations were employed to elucidate the molecular structure of "hypercoordinated" species and the energetics of water-elimination reactions of uranyl acetone complexes observed in earlier work (Rios, D.; Rutkowski, P. X.; Van Stipdonk, M. J.; Gibson, J. K. Inorg. Chem. 2011, 50, 4781). It is shown that the "hypercoordinated" species contain diacetone alcohol ligands bonded in either bidentate or monodentate fashion, which are indistinguishable from (acetone)2 in mass spectrometry. Calculations confirm that four diacetone ligands can form stable complexes, but that the effective number of atoms coordinating with uranium in the equatorial plane doesmore » not exceed five. Diacetone alcohol ligands are shown to form mesityl oxide ligands and alkoxide species through the elimination of water, providing an explanation for the observed water-elimination reactions.« less

Models of S/π interactions in protein structures: Comparison of the H2S–benzene complex with PDB data

PubMed Central

Ringer, Ashley L.; Senenko, Anastasia; Sherrill, C. David

2007-01-01

S/π interactions are prevalent in biochemistry and play an important role in protein folding and stabilization. Geometries of cysteine/aromatic interactions found in crystal structures from the Brookhaven Protein Data Bank (PDB) are analyzed and compared with the equilibrium configurations predicted by high-level quantum mechanical results for the H2S–benzene complex. A correlation is observed between the energetically favorable configurations on the quantum mechanical potential energy surface of the H2S–benzene model and the cysteine/aromatic configurations most frequently found in crystal structures of the PDB. In contrast to some previous PDB analyses, configurations with the sulfur over the aromatic ring are found to be the most important. Our results suggest that accurate quantum computations on models of noncovalent interactions may be helpful in understanding the structures of proteins and other complex systems. PMID:17766371

Kinetics of thermolysis of lanthanum nitrate with hexamethylenetetramine: Crystal structure, TG-DSC, impact and friction sensitivity studies, Part-96

NASA Astrophysics Data System (ADS)

Nibha; Baranwal, B. P.; Singh, Gurdip; Singh, C. P.; Daniliuc, Constantin G.; Soni, P. K.; Nath, Yogeshwar

2014-11-01

The development of high energetic materials includes process ability and the ability to attain insensitive munitions (IM). This paper investigates the preparation of lanthanum metal nitrate complex of hexamethylenetetramine in water at room temperature. This complex of molecular formulae [La (NO3)2(H2O)6] (2HMTA) (NO3-) (H2O) was characterized by X-ray crystallography. Thermal decomposition was investigated using TG, TG-DSC and ignition delay measurements. Kinetic analysis of isothermal TG data has been investigated using model fitting methods as well as model free isoconversional methods. The sensitivity measurements towards mechanical destructive stimuli such as impact and friction were carried out and the complex was found to be insensitive. In order to identify the end product of thermolysis, X-ray diffraction patterns of end product was carried out which proves the formation of La2O3.

Energetic neutron and gamma-ray spectra under the earth radiation belts according to ``SALUTE-7''-``KOSMOS-1686'' orbital complex and ``CORONAS-I'' satellite data

NASA Astrophysics Data System (ADS)

Bogomolov, A. V.; Dmitriev, A. V.; Myagkova, I. N.; Ryumin, S. P.; Smirnova, O. N.; Sobolevsky, I. M.

The spectra of neutrons > 10 MeV and gamma-rays 1.5-100 MeV under the Earth Radiation Belts, restored from the data, obtained onboard orbital complex ``SALUTE-7''-``KOSMOS-1686'', are presented. The spectra shapes are similar to those for albedo neutrons and gamma-rays, but absolute values of their fluxes (0.2 cm^-2 s^-1 for neutrons, 0.8 cm^-2 s^-1 for gamma-rays at the equator and 1.2 cm^-2 s^-1, 1.9 cm^-2 s^-1, accordingly, at L=1.9) are several times as large. It is possibly explained by the fact that most of the detected particles were produced by the cosmic ray interactions with the orbital complex matter. Neutron and gamma-ray fluxes obtained from ``CORONAS-I'' data are near those for albedo particles.

Potential health effects of space radiation

NASA Technical Reports Server (NTRS)

Yang, Chui-Hsu; Craise, Laurie M.

1993-01-01

Crewmembers on missions to the Moon or Mars will be exposed to radiation belts, galactic cosmic rays, and possibly solar particle events. The potential health hazards due to these space radiations must be considered carefully to ensure the success of space exploration. Because there is no human radioepidemiological data for acute and late effects of high-LET (Linear-Energy-Transfer) radiation, the biological risks of energetic charged particles have to be estimated from experimental results on animals and cultured cells. Experimental data obtained to date indicate that charged particle radiation can be much more effective than photons in causing chromosome aberrations, cell killing, mutation, and tumor induction. The relative biological effectiveness (RBE) varies with biological endpoints and depends on the LET of heavy ions. Most lesions induced by low-LET radiation can be repaired in mammalian cells. Energetic heavy ions, however, can produce large complex DNA damages, which may lead to large deletions and are irreparable. For high-LET radiation, therefore, there are less or no dose rate effects. Physical shielding may not be effective in minimizing the biological effects on energetic heavy ions, since fragments of the primary particles can be effective in causing biological effects. At present the uncertainty of biological effects of heavy particles is still very large. With further understanding of the biological effects of space radiation, the career doses can be kept at acceptable levels so that the space radiation environment need not be a barrier to the exploitation of the promise of space.

Chemical Impact of Solar Energetic Particle Event From The Young Sun: Implications for the Origin of Prebiotic Chemistry and the Fain Young Sun Paradox

NASA Astrophysics Data System (ADS)

Airapetian, V.; Gronoff, G.; Hébrard, E.; Danchi, W.

2015-12-01

Understanding how the simple molecules present on the early Earth and possibly Mars may have set a path for complex biological molecules, the building blocks of life, represents one of greatest unsolved questions. Here we present a new model of the rise of the abiotic nitrogen fixation and associated pre-biotic chemistry in the early Earth and Mars atmosphere mediated by solar eruptive events. Our physical models of interaction of magnetic clouds ejected from the young Sun with magnetospheres of the early Earth show significant perturbations of geomagnetic fields that produce extended polar caps. These polar caps provide pathways for energetic particles associated with magnetic clouds to penetrate into the nitrogen-rich weakly reducing atmosphere and initiate the reactive chemistry by breaking molecular nitrogen, carbon dioxide, methane and producing hydrogen cyanide, the essential compound for life. The model also shows that contrary to the current models of warming of early Earth and Mars, major atmospheric constituents, CO2 and CH4 will be destroyed due to collisional dissociation with energetic particles. Instead, efficient formation of the potent greenhouse gas, nitrous oxide, as a by-product of these processes is expected. This mechanism can consistently explain the Faint Young Sun's paradox for the early atmospheres of Earth and Mars. Our new model provides insight into how life may have initiated on Earth and Mars and how to search for the spectral signatures on planets "pregnant" with the potential for life.

Modeling Solar Energetic Particle Transport near a Wavy Heliospheric Current Sheet

NASA Astrophysics Data System (ADS)

Battarbee, Markus; Dalla, Silvia; Marsh, Mike S.

2018-02-01

Understanding the transport of solar energetic particles (SEPs) from acceleration sites at the Sun into interplanetary space and to the Earth is an important question for forecasting space weather. The interplanetary magnetic field (IMF), with two distinct polarities and a complex structure, governs energetic particle transport and drifts. We analyze for the first time the effect of a wavy heliospheric current sheet (HCS) on the propagation of SEPs. We inject protons close to the Sun and propagate them by integrating fully 3D trajectories within the inner heliosphere in the presence of weak scattering. We model the HCS position using fits based on neutral lines of magnetic field source surface maps (SSMs). We map 1 au proton crossings, which show efficient transport in longitude via HCS, depending on the location of the injection region with respect to the HCS. For HCS tilt angles around 30°–40°, we find significant qualitative differences between A+ and A‑ configurations of the IMF, with stronger fluences along the HCS in the former case but with a distribution of particles across a wider range of longitudes and latitudes in the latter. We show how a wavy current sheet leads to longitudinally periodic enhancements in particle fluence. We show that for an A+ IMF configuration, a wavy HCS allows for more proton deceleration than a flat HCS. We find that A‑ IMF configurations result in larger average fluences than A+ IMF configurations, due to a radial drift component at the current sheet.

Energetic plasticity underlies a variable response to ocean acidification in the pteropod, Limacina helicina antarctica.

PubMed

Seibel, Brad A; Maas, Amy E; Dierssen, Heidi M

2012-01-01

Ocean acidification, caused by elevated seawater carbon dioxide levels, may have a deleterious impact on energetic processes in animals. Here we show that high PCO(2) can suppress metabolism, measured as oxygen consumption, in the pteropod, L. helicina forma antarctica, by ∼20%. The rates measured at 180-380 µatm (MO(2)  =  1.25 M(-0.25), p  =  0.007) were significantly higher (ANCOVA, p  =  0.004) than those measured at elevated target CO(2) levels in 2007 (789-1000 µatm,  =  0.78 M(-0.32), p  =  0.0008; Fig. 1). However, we further demonstrate metabolic plasticity in response to regional phytoplankton concentration and that the response to CO(2) is dependent on the baseline level of metabolism. We hypothesize that reduced regional Chl a levels in 2008 suppressed metabolism and masked the effect of ocean acidification. This effect of food limitation was not, we postulate, merely a result of gut clearance and specific dynamic action, but rather represents a sustained metabolic response to regional conditions. Thus, pteropod populations may be compromised by climate change, both directly via CO(2)-induced metabolic suppression, and indirectly via quantitative and qualitative changes to the phytoplankton community. Without the context provided by long-term observations (four seasons) and a multi-faceted laboratory analysis of the parameters affecting energetics, the complex response of polar pteropods to ocean acidification may be masked or misinterpreted.

Energetic Plasticity Underlies a Variable Response to Ocean Acidification in the Pteropod, Limacina helicina antarctica

PubMed Central

Seibel, Brad A.; Maas, Amy E.; Dierssen, Heidi M.

2012-01-01

Ocean acidification, caused by elevated seawater carbon dioxide levels, may have a deleterious impact on energetic processes in animals. Here we show that high PCO2 can suppress metabolism, measured as oxygen consumption, in the pteropod, L. helicina forma antarctica, by ∼20%. The rates measured at 180–380 µatm (MO2  = 1.25 M−0.25, p = 0.007) were significantly higher (ANCOVA, p  =  0.004) than those measured at elevated target CO2 levels in 2007 (789–1000 µatm,  =  0.78 M−0.32, p  =  0.0008; Fig. 1). However, we further demonstrate metabolic plasticity in response to regional phytoplankton concentration and that the response to CO2 is dependent on the baseline level of metabolism. We hypothesize that reduced regional Chl a levels in 2008 suppressed metabolism and masked the effect of ocean acidification. This effect of food limitation was not, we postulate, merely a result of gut clearance and specific dynamic action, but rather represents a sustained metabolic response to regional conditions. Thus, pteropod populations may be compromised by climate change, both directly via CO2-induced metabolic suppression, and indirectly via quantitative and qualitative changes to the phytoplankton community. Without the context provided by long-term observations (four seasons) and a multi-faceted laboratory analysis of the parameters affecting energetics, the complex response of polar pteropods to ocean acidification may be masked or misinterpreted. PMID:22536312

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

Herdiwijaya, Dhani, E-mail: dhani@as.itb.ac.id; Rachman, Abdul

Any man-made object in Earth's orbit that no longer serves a useful purpose is classified as orbital debris. Debris objects come from a variety of sources. The majority is related to satellite fragmentation. Other major sources of debris are propulsion systems, and fragmentation of spent upper stages, payload and mission related debris. Serious concern about orbital debris has been growing. Knowledge of the future debris environment is important to both satellite designers, and mission planners, who need to know what hazards a satellite might encounter during the course of its mission. Therefore, it is important to know how much debrismore » is in orbit, where it is located, and when it will decay. The debris environment is complex and dynamically evolving. Objects of different shape and size behave differently in orbit. The geoeffectiveness space environments include solar flux at 10.7 cm, solar energetic particles flux or speed, solar wind flow pressure, electric field, and geomagnetic indices. We study the decaying orbital debris from Tracking and Impact Prediction (TIP) messages in conjuction with geoeffectiveness space environments through time epoch correlation. We found that the decaying and reentry orbital debris are triggered by space environment enhancement within at least one week before reentry. It is not necessary a transient or high energetic and severe solar storm events are needed in decaying processes. We propose that the gradual enhancement processes of space environment will cause satellite surface charging due to energetic electron and enhance drag force.« less

Calcium Signaling and Reactive Oxygen Species in Mitochondria.

PubMed

Bertero, Edoardo; Maack, Christoph

2018-05-11

In heart failure, alterations of Na + and Ca 2+ handling, energetic deficit, and oxidative stress in cardiac myocytes are important pathophysiological hallmarks. Mitochondria are central to these processes because they are the main source for ATP, but also reactive oxygen species (ROS), and their function is critically controlled by Ca 2+ During physiological variations of workload, mitochondrial Ca 2+ uptake is required to match energy supply to demand but also to keep the antioxidative capacity in a reduced state to prevent excessive emission of ROS. Mitochondria take up Ca 2+ via the mitochondrial Ca 2+ uniporter, which exists in a multiprotein complex whose molecular components were identified only recently. In heart failure, deterioration of cytosolic Ca 2+ and Na + handling hampers mitochondrial Ca 2+ uptake and the ensuing Krebs cycle-induced regeneration of the reduced forms of NADH (nicotinamide adenine dinucleotide) and NADPH (nicotinamide adenine dinucleotide phosphate), giving rise to energetic deficit and oxidative stress. ROS emission from mitochondria can trigger further ROS release from neighboring mitochondria termed ROS-induced ROS release, and cross talk between different ROS sources provides a spatially confined cellular network of redox signaling. Although low levels of ROS may serve physiological roles, higher levels interfere with excitation-contraction coupling, induce maladaptive cardiac remodeling through redox-sensitive kinases, and cell death through mitochondrial permeability transition. Targeting the dysregulated interplay between excitation-contraction coupling and mitochondrial energetics may ameliorate the progression of heart failure. © 2018 American Heart Association, Inc.

Intermolecular interaction in nucleobases and dimethyl sulfoxide/water molecules: A DFT, NBO, AIM and NCI analysis.

PubMed

Venkataramanan, Natarajan Sathiyamoorthy; Suvitha, Ambigapathy; Kawazoe, Yoshiyuki

2017-11-01

This study aims to cast light on the physico-chemical nature and energetics of interactions between the nucleobases and water/DMSO molecules which occurs through the non-conventional CH⋯O/N-H bonds using a comprehensive quantum-chemical approach. The computed interaction energies do not show any appreciable change for all the nucleobase-solvent complexes, conforming the experimental findings on the hydration enthalpies. Compared to water, DMSO form complexes with high interaction energies. The quantitative molecular electrostatic potentials display a charge transfer during the complexation. NBO analysis shows the nucleobase-DMSO complexes, have higher stabilization energy values than the nucleobase-water complexes. AIM analysis illustrates that the in the nucleobase-DMSO complexes, SO⋯H-N type interaction have strongest hydrogen bond strength with high E HB values. Furthermore, the Laplacian of electron density and total electron density were negative indicating the partial covalent nature of bonding in these systems, while the other bonds are classified as noncovalent interactions. EDA analysis indicates, the electrostatic interaction is more pronounced in the case of nucleobase-water complexes, while the dispersion contribution is more dominant in nucleobase-DMSO complexes. NCI-RDG analysis proves the existence of strong hydrogen bonding in nucleobase-DMSO complex, which supports the AIM results. Copyright © 2017 Elsevier Inc. All rights reserved.

Structure of caa(3) cytochrome c oxidase--a nature-made enzyme-substrate complex.

PubMed

Noor, Mohamed Radzi; Soulimane, Tewfik

2013-05-01

Aerobic respiration, the energetically most favorable metabolic reaction, depends on the action of terminal oxidases that include cytochrome c oxidases. The latter forms a part of the heme-copper oxidase superfamily and consists of three different families (A, B, and C types). The crystal structures of all families have now been determined, allowing a detailed structural comparison from evolutionary and functional perspectives. The A2-type oxidase, exemplified by the Thermus thermophilus caa(3) oxidase, contains the substrate cytochrome c covalently bound to the enzyme complex. In this article, we highlight the various features of caa(3) enzyme and provide a discussion of their importance, including the variations in the proton and electron transfer pathways.

Quantum chemical calculations of anion complex [B12Hx(CF3)12-x]2-, x = 9 - 12

NASA Astrophysics Data System (ADS)

Koblova, Elena A.; Saldin, Vitaly I.; Ustinov, Alexander Yu.

2016-12-01

The geometric, energetic, spectral and electronic properties of the most stable isomers of B12Hx(CF3)12-X2- anion complex with x = 9 - 12 have been studied using Density Functional Theory (B3LYP/6-311++G**). It was shown that these isomers are characterized by the preference to form the most symmetric structures with uniformly distributed charge densities. However, when replacing a hydrogen atom with fluoromethyl group, an inductive effect occurs. Blue shifts in the IR spectrum compared to the vibrations of the free CF3 molecule are in the range of 2 - 69 cm-1 and points to the stability of B12Hx(CF3)12-x2- anions.

1H NMR study of the complexation of aromatic drugs with dimethylxanthine derivatives

NASA Astrophysics Data System (ADS)

Hernandez Santiago, A. A.; Gonzalez Flores, M.; Rosas Castilla, S. A.; Cervantes Tavera, A. M.; Gutierrez Perez, R.; Khomich, V. V.; Ovchinnikov, D. V.; Parkes, H. G.; Evstigneev, M. P.

2012-02-01

With an aim of searching efficient interceptors of aromatic drugs, the self- and hetero-association of dimethylxanthine derivatives with different structures, selected according to Strategy 1 (variation of the position of methyl groups) and Strategy 2 (variation of the length of sbnd (CH2)nsbnd COOH group), with aromatic drug molecules: Ethidium Bromide, Proflavine and Daunomycin, were studied using 1H NMR spectroscopy. It was found that the association proceeds in a form of stacking-type complexation and its energetics is relatively independent on the structure of the dimethylxanthines. However, on average, the dimethylxanthines possess higher hetero-association constant and, hence, higher interceptor ability as compared to the trimethylxanthine, Caffeine, used during the past two decades as a typical interceptor molecule.

A 1:2 crystalline complex of ApA:proflavine: a model for binding to single-stranded regions in RNA.

PubMed Central

Neidle, S; Taylor, G; Sanderson, M

1978-01-01

The structure of a 1"2 complex of adenylyl-(3',5')-adenosine phosphate and proflavine hemisulfate has been determined using the methods of x-ray crystallography. Since the ApA does not form a mini double helix, it may serve as a model for the interaction of planar molecules with single stranded nucleic acids. The dinucleotide adopts an extended conformation with the adenines in adjacent molecules forming base pairs. A most unusual feature of the molecule is that it does not obey the "rigid nucleotide" concept although none of the torsion angles occur in energetically unfavourable regions. This is most probably due to the strong interactions between the proflavine and the oligonucleotide. PMID:724521

Hundreds MeV monoenergetic proton bunch from interaction of 10{sup 20-21} W/cm{sup 2} circularly polarized laser pulse with tailored complex target

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

Zhang, Z. M.; Laser Fusion Research Center, CAEP, Mianyang 621900; He, X. T.

A complex target (CT) configuration tailored for generating high quality proton bunch by circularly polarized laser pulses at intensities of 10{sup 20-21} W/cm{sup 2} is proposed. Two-dimensional particle-in-cell simulations show that both the collimation and mono-energetic qualities of the accelerated proton bunch obtained using a front-shaped thin foil can be greatly enhanced by the backside inhomogeneous plasma layer. The main mechanisms for improving the accelerated protons are identified and discussed. These include stabilization of the photon cavity, providing hole-boring supplementary acceleration and suppressing the thermal-electron effects. A theory for tailoring the CT parameters is also presented.

Determination of Foraging Thresholds and Effects of Application on Energetic Carrying Capacity for Waterfowl

PubMed Central

2015-01-01

Energetic carrying capacity of habitats for wildlife is a fundamental concept used to better understand population ecology and prioritize conservation efforts. However, carrying capacity can be difficult to estimate accurately and simplified models often depend on many assumptions and few estimated parameters. We demonstrate the complex nature of parameterizing energetic carrying capacity models and use an experimental approach to describe a necessary parameter, a foraging threshold (i.e., density of food at which animals no longer can efficiently forage and acquire energy), for a guild of migratory birds. We created foraging patches with different fixed prey densities and monitored the numerical and behavioral responses of waterfowl (Anatidae) and depletion of foods during winter. Dabbling ducks (Anatini) fed extensively in plots and all initial densities of supplemented seed were rapidly reduced to 10 kg/ha and other natural seeds and tubers combined to 170 kg/ha, despite different starting densities. However, ducks did not abandon or stop foraging in wetlands when seed reduction ceased approximately two weeks into the winter-long experiment nor did they consistently distribute according to ideal-free predictions during this period. Dabbling duck use of experimental plots was not related to initial seed density, and residual seed and tuber densities varied among plant taxa and wetlands but not plots. Herein, we reached several conclusions: 1) foraging effort and numerical responses of dabbling ducks in winter were likely influenced by factors other than total food densities (e.g., predation risk, opportunity costs, forager condition), 2) foraging thresholds may vary among foraging locations, and 3) the numerical response of dabbling ducks may be an inconsistent predictor of habitat quality relative to seed and tuber density. We describe implications on habitat conservation objectives of using different foraging thresholds in energetic carrying capacity models and suggest scientists reevaluate assumptions of these models used to guide habitat conservation. PMID:25790255

Nonlinear Whistler Wave Physics in the Radiation Belts

NASA Astrophysics Data System (ADS)

Crabtree, Chris

2016-10-01

Wave particle interactions between electrons and whistler waves are a dominant mechanism for controlling the dynamics of energetic electrons in the radiation belts. They are responsible for loss, via pitch-angle scattering of electrons into the loss cone, and energization to millions of electron volts. It has previously been theorized that large amplitude waves on the whistler branch may scatter their wave-vector nonlinearly via nonlinear Landau damping leading to important consequences for the global distribution of whistler wave energy density and hence the energetic electrons. It can dramatically reduce the lifetime of energetic electrons in the radiation belts by increasing the pitch angle scattering rate. The fundamental building block of this theory has now been confirmed through laboratory experiments. Here we report on in situ observations of wave electro-magnetic fields from the EMFISIS instrument on board NASA's Van Allen Probes that show the signatures of nonlinear scattering of whistler waves in the inner radiation belts. In the outer radiation belts, whistler mode chorus is believed to be responsible for the energization of electrons from 10s of Kev to MeV energies. Chorus is characterized by bursty large amplitude whistler mode waves with frequencies that change as a function of time on timescales corresponding to their growth. Theories explaining the chirping have been developed for decades based on electron trapping dynamics in a coherent wave. New high time resolution wave data from the Van Allen probes and advanced spectral techniques are revealing that the wave dynamics is highly structured, with sub-elements consisting of multiple chirping waves with discrete frequency hops between sub-elements. Laboratory experiments with energetic electron beams are currently reproducing the complex frequency vs time dynamics of whistler waves and in addition revealing signatures of wave-wave and beat-wave nonlinear wave-particle interactions. These new data suggest that these weak turbulence processes may be playing a role in saturating the nonlinear instability.

Structural Basis for a Unique ATP Synthase Core Complex from Nanoarcheaum equitans*

PubMed Central

Mohanty, Soumya; Jobichen, Chacko; Chichili, Vishnu Priyanka Reddy; Velázquez-Campoy, Adrián; Low, Boon Chuan; Hogue, Christopher W. V.; Sivaraman, J.

2015-01-01

ATP synthesis is a critical and universal life process carried out by ATP synthases. Whereas eukaryotic and prokaryotic ATP synthases are well characterized, archaeal ATP synthases are relatively poorly understood. The hyperthermophilic archaeal parasite, Nanoarcheaum equitans, lacks several subunits of the ATP synthase and is suspected to be energetically dependent on its host, Ignicoccus hospitalis. This suggests that this ATP synthase might be a rudimentary machine. Here, we report the crystal structures and biophysical studies of the regulatory subunit, NeqB, the apo-NeqAB, and NeqAB in complex with nucleotides, ADP, and adenylyl-imidodiphosphate (non-hydrolysable analog of ATP). NeqB is ∼20 amino acids shorter at its C terminus than its homologs, but this does not impede its binding with NeqA to form the complex. The heterodimeric NeqAB complex assumes a closed, rigid conformation irrespective of nucleotide binding; this differs from its homologs, which require conformational changes for catalytic activity. Thus, although N. equitans possesses an ATP synthase core A3B3 hexameric complex, it might not function as a bona fide ATP synthase. PMID:26370083

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

Accumulation of Succinate in Cardiac Ischemia Primarily Occurs via Canonical Krebs Cycle Activity.

PubMed

Zhang, Jimmy; Wang, Yves T; Miller, James H; Day, Mary M; Munger, Joshua C; Brookes, Paul S

2018-05-29

Succinate accumulates during ischemia, and its oxidation at reperfusion drives injury. The mechanism of ischemic succinate accumulation is controversial and is proposed to involve reversal of mitochondrial complex II. Herein, using stable-isotope-resolved metabolomics, we demonstrate that complex II reversal is possible in hypoxic mitochondria but is not the primary succinate source in hypoxic cardiomyocytes or ischemic hearts. Rather, in these intact systems succinate primarily originates from canonical Krebs cycle activity, partly supported by aminotransferase anaplerosis and glycolysis from glycogen. Augmentation of canonical Krebs cycle activity with dimethyl-α-ketoglutarate both increases ischemic succinate accumulation and drives substrate-level phosphorylation by succinyl-CoA synthetase, improving ischemic energetics. Although two-thirds of ischemic succinate accumulation is extracellular, the remaining one-third is metabolized during early reperfusion, wherein acute complex II inhibition is protective. These results highlight a bifunctional role for succinate: its complex-II-independent accumulation being beneficial in ischemia and its complex-II-dependent oxidation being detrimental at reperfusion. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

A system-wide analysis using a senior-friendly hospital framework identifies current practices and opportunities for improvement in the care of hospitalized older adults.

PubMed

Wong, Ken S; Ryan, David P; Liu, Barbara A

2014-11-01

Older adults are vulnerable to hospital-associated complications such as falls, pressure ulcers, functional decline, and delirium, which can contribute to prolonged hospital stay, readmission, and nursing home placement. These vulnerabilities are exacerbated when the hospital's practices, services, and physical environment are not sufficiently mindful of the complex, multidimensional needs of frail individuals. Several frameworks have emerged to help hospitals examine how organization-wide processes can be customized to avoid these complications. This article describes the application of one such framework-the Senior-Friendly Hospital (SFH) framework adopted in Ontario, Canada-which comprises five interrelated domains: organizational support, processes of care, emotional and behavioral environment, ethics in clinical care and research, and physical environment. This framework provided the blueprint for a self-assessment of all 155 adult hospitals across the province of Ontario. The system-wide analysis identified practice gaps and promising practices within each domain of the SFH framework. Taken together, these results informed 12 recommendations to support hospitals at all stages of development in becoming friendly to older adults. Priorities for system-wide action were identified, encouraging hospitals to implement or further develop their processes to better address hospital-acquired delirium and functional decline. These recommendations led to collaborative action across the province, including the development of an online toolkit and the identification of accountability indicators to support hospitals in quality improvement focusing on senior-friendly care. © 2014, Copyright the Authors Journal compilation © 2014, The American Geriatrics Society.

Energetic-particle-induced geodesic acoustic mode.

PubMed

Fu, G Y

2008-10-31

A new energetic particle-induced geodesic acoustic mode (EGAM) is shown to exist. The mode frequency and mode structure are determined nonperturbatively by energetic particle kinetic effects. In particular the EGAM frequency is found to be substantially lower than the standard GAM frequency. The radial mode width is determined by the energetic particle drift orbit width and can be fairly large for high energetic particle pressure and large safety factor. These results are consistent with the recent experimental observation of the beam-driven n=0 mode in DIII-D.

Simulation of the radiation exposure in space during a large solar energetic particle event with GEANT4

NASA Astrophysics Data System (ADS)

Matthiä, Daniel; Berger, Thomas; Puchalska, Monika; Reitz, Guenther

The radiation field in space is complex due to the various contributing sources and astronauts at the International Space Station (ISS) in low Earth orbit or beyond are exposed to significantly increased doses compared to on ground or in the lower atmosphere. The main sources of the increased radiation level are Galactic Cosmic Ray (GCR) particles, mainly fully charged ions from hydrogen to iron with energies up to hundreds of GeV per nucleon and more, trapped protons from the radiation belts with energies up to several hundreds of MeV, and solar energetic particles up to several GeV released in large eruptions on the sun related to solar x-ray flares and coronal mass ejections. While the intensities of Galactic Cosmic Rays and trapped protons are relatively stable and changing slowly over the solar cycle, solar energetic particle events last for several hours up to days and are characterized by strong increases in the particle intensity. The radiation exposure during a large particle event can be very harmful to astronauts especially during extra vehicular activities and outside the protective magnetic field of the Earth. The MATROSHKA human phantom was and is used on the International Space Station to measure the radiation exposure in and outside ISS in order to evaluate the radiation risk in low Earth orbit. A voxel-based description of the MATROSHKA phantom (NUNDO-Numerical RANDO Model) was used in the present work to numerically estimate the radiation exposure of the human body and the individual organs during a large solar particle event. The transport of primary protons following an exponential energy distribution was simulated in order to calculate the energy deposition and organ doses in the MATROSHKA phantom during such an event taking into account different amounts of shielding provided by a surrounding aluminum shell. The primary particle energy distribution used in this work follows the description of the spectrum of the solar energetic particle event in August 1972 in the energy range from 45 MeV to 1 GeV. The transport calculations of the energetic particles through the shielding and the phantom model were performed using the Monte-Carlo code GEANT4.

Q&A: Friends (but sometimes foes) within: the complex evolutionary ecology of symbioses between host and microbes.

PubMed

Gerardo, Nicole; Hurst, Gregory

2017-12-27

Over the past decade, there has been a pronounced shift in the study of host-microbe associations, with recognition that many of these associations are beneficial, and often critical, for a diverse array of hosts. There may also be pronounced benefits for the microbes, though this is less well empirically understood. Significant progress has been made in understanding how ecology and evolution shape simple associations between hosts and one or a few microbial species, and this work can serve as a foundation to study the ecology and evolution of host associations with their often complex microbial communities (microbiomes).

Exercise contagion in a global social network.

PubMed

Aral, Sinan; Nicolaides, Christos

2017-04-18

We leveraged exogenous variation in weather patterns across geographies to identify social contagion in exercise behaviours across a global social network. We estimated these contagion effects by combining daily global weather data, which creates exogenous variation in running among friends, with data on the network ties and daily exercise patterns of ∼1.1M individuals who ran over 350M km in a global social network over 5 years. Here we show that exercise is socially contagious and that its contagiousness varies with the relative activity of and gender relationships between friends. Less active runners influence more active runners, but not the reverse. Both men and women influence men, while only women influence other women. While the Embeddedness and Structural Diversity theories of social contagion explain the influence effects we observe, the Complex Contagion theory does not. These results suggest interventions that account for social contagion will spread behaviour change more effectively.

Dissecting "Peer Presence" and "Decisions" to Deepen Understanding of Peer Influence on Adolescent Risky Choice.

PubMed

Somerville, Leah H; Haddara, Nadia; Sasse, Stephanie F; Skwara, Alea C; Moran, Joseph M; Figner, Bernd

2018-04-27

This study evaluated the aspects of complex decisions influenced by peers, and components of peer involvement influential to adolescents' risky decisions. Participants (N = 140) aged 13-25 completed the Columbia Card Task (CCT), a risky choice task, isolating deliberation-reliant and affect-reliant decisions while alone, while a friend monitors choices, and while a friend is merely present. There is no condition in which a nonfriend peer is present. Results demonstrated the risk-increasing peer effect occurred in the youngest participants in the cold CCT and middle-late adolescents in the hot CCT, whereas other ages and contexts showed a risk-decreasing peer effect. Mere presence was not sufficient to influence risky behavior. These boundaries in age, decision, and peer involvement constrain prevailing models of adolescent peer influence. © 2018 Society for Research in Child Development.

Consumer friendly or reader hostile? An evaluation of the readability of DTC print ads.

PubMed

Sheehan, Kim

2008-01-01

The Food and Drug Administration requires advertisements promoting prescription drugs to be written in "consumer friendly" language. The purpose of this study is to examine the language of Direct-to-Consumer prescription drug advertisements to determine if such language is easy for consumers to read and understand. A series of advertisements for a variety of products, appearing in popular consumer magazines, were analyzed using the Flesch and Gunning-Fogg formulas to determine if DTC advertisements are more or less complex than other advertisements that consumers read today. Results indicate that DTC ads are among the most difficult print ads to read. Additionally, certain types of information contained in these print ads (such as information discussing a drug's risks and contraindications) are significantly more difficult to read than information in any other type of ad copy in magazines today. Implications for DTC marketers and the FDA are included.

Caffeine: Friend or Foe?

PubMed

Doepker, Candace; Lieberman, Harris R; Smith, Andrew Paul; Peck, Jennifer D; El-Sohemy, Ahmed; Welsh, Brian T

2016-01-01

The debate on the safety of and regulatory approaches for caffeine continues among various stakeholders and regulatory authorities. This decision-making process comes with significant challenges, particularly when considering the complexities of the available scientific data, making the formulation of clear science-based regulatory guidance more difficult. To allow for discussions of a number of key issues, the North American Branch of the International Life Sciences Institute (ILSI) convened a panel of subject matter experts for a caffeine-focused session entitled "Caffeine: Friend or Foe?," which was held during the 2015 ILSI Annual Meeting. The panelists' expertise covered topics ranging from the natural occurrence of caffeine in plants and interindividual metabolism of caffeine in humans to specific behavioral, reproductive, and cardiovascular effects related to caffeine consumption. Each presentation highlighted the potential risks, benefits, and challenges that inform whether caffeine exposure warrants concern. This paper aims to summarize the key topics discussed during the session.

Standards-Based Procedural Phenotyping: The Arden Syntax on i2b2.

PubMed

Mate, Sebastian; Castellanos, Ixchel; Ganslandt, Thomas; Prokosch, Hans-Ulrich; Kraus, Stefan

2017-01-01

Phenotyping, or the identification of patient cohorts, is a recurring challenge in medical informatics. While there are open source tools such as i2b2 that address this problem by providing user-friendly querying interfaces, these platforms lack semantic expressiveness to model complex phenotyping algorithms. The Arden Syntax provides procedural programming language construct, designed specifically for medical decision support and knowledge transfer. In this work, we investigate how language constructs of the Arden Syntax can be used for generic phenotyping. We implemented a prototypical tool to integrate i2b2 with an open source Arden execution environment. To demonstrate the applicability of our approach, we used the tool together with an Arden-based phenotyping algorithm to derive statistics about ICU-acquired hypernatremia. Finally, we discuss how the combination of i2b2's user-friendly cohort pre-selection and Arden's procedural expressiveness could benefit phenotyping.

STS-90 M.S. Williams with the CSA waves to family and friends near Pad 39B

NASA Technical Reports Server (NTRS)

1998-01-01

STS-90 Mission Specialist Dafydd (Dave) Williams, M.D., with the Canadian Space Agency speaks with friends and family members near Launch Pad 39B, from which he and the rest of the seven-member crew are scheduled to launch aboard Columbia on May 16 at 2:19 p.m. EDT. The astronauts are under strict health stabilization guidelines to protect them from close contact with persons who do not have health stabilization clearance. This is the 25th flight of Columbia and the 90th mission flown since the start of the Space Shuttle program. STS-90 is a nearly 17-day life sciences research flight that will focus on the most complex and least understood part of the human body -- the nervous system. Neurolab will examine the effects of spaceflight on the brain, spinal cord, peripheral nerves and sensory organs in the human body.

STS-90 M.S. Kathryn Hire waves to family and friends near Pad 39B

NASA Technical Reports Server (NTRS)

1998-01-01

STS-90 Mission Specialist Kathryn (Kay) Hire waves to friends and family members near Launch Pad 39B, from which she and the rest of the seven-member crew are scheduled to launch aboard Columbia on May 16 at 2:19 p.m. EDT. The astronauts are under strict health stabilization guidelines to protect them from close contact with persons who do not have health stabilization clearance. This is the 25th flight of Columbia and the 90th mission flown since the start of the Space Shuttle program. STS- 90 is a nearly 17-day life sciences research flight that will focus on the most complex and least understood part of the human body -- the nervous system. Neurolab will examine the effects of spaceflight on the brain, spinal cord, peripheral nerves and sensory organs in the human body.

The Simple Rules of Social Contagion

PubMed Central

Hodas, Nathan O.; Lerman, Kristina

2014-01-01

It is commonly believed that information spreads between individuals like a pathogen, with each exposure by an informed friend potentially resulting in a naive individual becoming infected. However, empirical studies of social media suggest that individual response to repeated exposure to information is far more complex. As a proxy for intervention experiments, we compare user responses to multiple exposures on two different social media sites, Twitter and Digg. We show that the position of exposing messages on the user-interface strongly affects social contagion. Accounting for this visibility significantly simplifies the dynamics of social contagion. The likelihood an individual will spread information increases monotonically with exposure, while explicit feedback about how many friends have previously spread it increases the likelihood of a response. We provide a framework for unifying information visibility, divided attention, and explicit social feedback to predict the temporal dynamics of user behavior. PMID:24614301

Software systems for modeling articulated figures

NASA Technical Reports Server (NTRS)

Phillips, Cary B.

1989-01-01

Research in computer animation and simulation of human task performance requires sophisticated geometric modeling and user interface tools. The software for a research environment should present the programmer with a powerful but flexible substrate of facilities for displaying and manipulating geometric objects, yet insure that future tools have a consistent and friendly user interface. Jack is a system which provides a flexible and extensible programmer and user interface for displaying and manipulating complex geometric figures, particularly human figures in a 3D working environment. It is a basic software framework for high-performance Silicon Graphics IRIS workstations for modeling and manipulating geometric objects in a general but powerful way. It provides a consistent and user-friendly interface across various applications in computer animation and simulation of human task performance. Currently, Jack provides input and control for applications including lighting specification and image rendering, anthropometric modeling, figure positioning, inverse kinematics, dynamic simulation, and keyframe animation.

User-friendly chemistry takes center stage at ACS meeting

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

Pool, R.

1992-09-11

These days it seems that what chemistry needs more than anything else is a good p.r. agent. If you ask John or Joan Q. Public about the accomplishments of the chemical industry, chances are they'll mention Love Canal, CFCs destroying the ozone layer, or carcinogens in food. However, if the national meeting of the American Chemical Society in Washington, D.C., 2 weeks ago is any indication, chemists are working hard to fix the image problem. Nearly all of the two dozen press conferences held during the meeting focused on food, health topics, environment-friendly technology, or some other subject close tomore » consumers' hearts. And the scientific talks themselves reflected the same interests, with sessions such as Environmental Successes in the Chemical Industry', Food Phytochemicals for Cancer Prevention', Chemistry of Electrophilic Metal Complexes', New Advances in Polyolefin Polymers', Zapping acid rain with microwaves.'« less

Interchange mode excited by trapped energetic ions

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

Nishimura, Seiya, E-mail: n-seiya@kobe-kosen.ac.jp

2015-07-15

The kinetic energy principle describing the interaction between ideal magnetohydrodynamic (MHD) modes with trapped energetic ions is revised. A model is proposed on the basis of the reduced ideal MHD equations for background plasmas and the bounce-averaged drift-kinetic equation for trapped energetic ions. The model is applicable to large-aspect-ratio toroidal devices. Specifically, the effect of trapped energetic ions on the interchange mode in helical systems is analyzed. Results show that the interchange mode is excited by trapped energetic ions, even if the equilibrium states are stable to the ideal interchange mode. The energetic-ion-induced branch of the interchange mode might bemore » associated with the fishbone mode in helical systems.« less

Dynamics, Conformational Entropy, and Frustration in Protein-Protein Interactions Involving an Intrinsically Disordered Protein Domain.

PubMed

Lindström, Ida; Dogan, Jakob

2018-05-18

Intrinsically disordered proteins (IDPs) are abundant in the eukaryotic proteome. However, little is known about the role of subnanosecond dynamics and the conformational entropy that it represents in protein-protein interactions involving IDPs. Using nuclear magnetic resonance side chain and backbone relaxation, stopped-flow kinetics, isothermal titration calorimetry, and computational studies, we have characterized the interaction between the globular TAZ1 domain of the CREB binding protein and the intrinsically disordered transactivation domain of STAT2 (TAD-STAT2). We show that the TAZ1/TAD-STAT2 complex retains considerable subnanosecond motions, with TAD-STAT2 undergoing only a partial disorder-to-order transition. We report here the first experimental determination of the conformational entropy change for both binding partners in an IDP binding interaction and find that the total change even exceeds in magnitude the binding enthalpy and is comparable to the contribution from the hydrophobic effect, demonstrating its importance in the binding energetics. Furthermore, we show that the conformational entropy change for TAZ1 is also instrumental in maintaining a biologically meaningful binding affinity. Strikingly, a spatial clustering of very high amplitude motions and a cluster of more rigid sites in the complex exist, which through computational studies we found to overlap with regions that experience energetic frustration and are less frustrated, respectively. Thus, the residual dynamics in the bound state could be necessary for faster dissociation, which is important for proteins that interact with multiple binding partners.

Directionally Interacting Spheres and Rods Form Ordered Phases

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

Liu, Wenyan; Mahynski, Nathan A.; Gang, Oleg

The structures formed by mixtures of dissimilarly shaped nanoscale objects can significantly enhance our ability to produce nanoscale architectures. However, understanding their formation is a complex problem due to the interplay of geometric effects (entropy) and energetic interactions at the nanoscale. Spheres and rods are perhaps the most basic geometrical shapes and serve as convenient models of such dissimilar objects. The ordered phases formed by each of these individual shapes have already been explored, but, when mixed, spheres and rods have demonstrated only limited structural organization to date. We show using experiments and theory that the introduction of directional attractionsmore » between rod ends and isotropically interacting spherical nanoparticles (NPs) through DNA base pairing leads to the formation of ordered three-dimensional lattices. The spheres and rods arrange themselves in a complex alternating manner, where the spheres can form either a face-centered cubic (FCC) or hexagonal close-packed (HCP) lattice, or a disordered phase, as observed by in situ X-ray scattering. Increasing NP diameter at fixed rod length yields an initial transition from a disordered phase to the HCP crystal, energetically stabilized by rod-rod attraction across alternating crystal layers, as revealed by theory. In the limit of large NPs, the FCC structure is instead stabilized over the HCP by rod entropy. Thus, we propose that directionally specific attractions in mixtures of anisotropic and isotropic objects offer insight into unexplored self-assembly behavior of noncomplementary shaped particles.« less