Theoretical investigation of the role of clay edges in prebiotic peptide bond formation. II - Structures and thermodynamics of the activated complex species

NASA Technical Reports Server (NTRS)

Collins, Jack R.; Loew, Gilda H.; Luke, Brian T.; White, David H.

1988-01-01

Molecular orbital calculations are used to study amino acid activation by anhydride formation in neutral phosphates and in tetrahedral silicate and aluminate sites on clay edges. The results agree with previous ab initio studies of Luke et al. (1984) on the reactant species. Relative heats of formation of the anhydrides indicate the extent of anhydride formation to be the greatest for Al and the least for phosphate, which is the same order as the stability of hydrolysis.

Fire-scar formation in Jeffrey pine - mixed conifer forests in the Sierra San Pedro Martir, Mexico

Treesearch

Scott L. Stephens; Danny L. Fry; Brandon M. Collins; Carl N. Skinner; Ernesto Franco-Vizcaino; Travis J. Freed

2010-01-01

Little is known about the probability of fire-scar formation. In this study, we examined all mixed conifer trees for fire-scar formation in a 16 ha watershed that burned as part of a 2003 wildfire in Sierra San Pedro Ma´rtir National Park (SSPM), Mexico. In addition, we examine the probability of fire-scar formation in relation to the previous fire interval in forests...

The Complete, Temperature Resolved Spectrum of Methyl Formate Between 214 and 265 GHZ

NASA Astrophysics Data System (ADS)

McMillan, James P.; Fortman, Sarah; Neese, Christopher F.; De Lucia, Frank C.

2015-06-01

We have studied methyl formate, one of the so-called 'astronomical weeds', in the 214--265 GHz band. We have experimentally gathered a set of intensity calibrated, complete, and temperature resolved spectra from across the astronomically significant temperature range of 248--406 K. Using our previously reported method of analysis, the point by point method, we are capable of generating the complete spectrum at an arbitrary temperature. Thousands of lines, of nontrivial intensity, which were previously not included in the available astrophysical catalogs have been found. The sensitivity of the point by point analysis is such that we are able to identify lines which would not have manifest in a single scan across the band. The consequence has been to reveal not only a number of new methyl formate lines, but also trace amounts of contaminants. We show how the intensities from the contaminants can be removed with indiscernible impact on the signal from methyl formate. To do this we use the point by point results from our previous studies of these contaminants. The efficacy of this process serves as strong proof of concept for usage of our point by point results on the problem of the 'weeds'. The success of this approach for dealing with the weeds has also previously been reported. J.~McMillan, S.~Fortman, C.~Neese, F.~DeLucia, ApJ. 795, 56 (2014) S.~Fortman, J.~McMillan, C.~Neese, S.~Randall, and A.~Remijan, J.~Mol.~Spectrosc. 280, 11 (2012).

Condensation of cosmic analog material in microgravity conditions - Preliminary analysis of a first set of flights

NASA Technical Reports Server (NTRS)

Mancini, D.; Bussoletti, E.; Mennella, V.; Vittone, A. A.; Colangeli, L.; Mirra, C.; Stephens, J.; Nuth, J.; Lilleleht, L.; Furgeson, F.

1992-01-01

The first results of the STARDUST project, aimed at producing and analyzing cosmic-dust analog materials in microgravity conditions, are summarized. The discussion covers the purpose of the investigation, cosmic-dust formation and properties, previous simulations of cosmic-dust formation, the current approach, the microgravity experimental apparatus, and potential advantages of studying dust formation under microgravity conditions.

Education in the New Latino Diaspora: Policy and the Politics of Identity. Sociocultural Studies in Educational Policy Formation and Appropriation.

ERIC Educational Resources Information Center

Wortham, Stanton, Ed.; Murillo, Enrique G., Jr., Ed.; Hamann, Edmund T., Ed.

Many immigrant Latino families are settling in U.S. communities that previously had little Latino presence. Through case studies of such communities in Georgia, North Carolina, Maine, Colorado, Illinois, and Indiana, this book describes relations between host communities and newcomers, with particular focus on educational policy formation and…

Multi-epoch very long baseline interferometric observations of the nuclear starburst region of NGC 253: Improved modeling of the supernova and star formation rates

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

Rampadarath, H.; Morgan, J. S.; Tingay, S. J.

2014-01-01

The results of multi-epoch observations of the southern starburst galaxy, NGC 253, with the Australian Long Baseline Array at 2.3 GHz are presented. As with previous radio interferometric observations of this galaxy, no new sources were discovered. By combining the results of this survey with Very Large Array observations at higher frequencies from the literature, spectra were derived and a free-free absorption model was fitted of 20 known sources in NGC 253. The results were found to be consistent with previous studies. The supernova remnant, 5.48-43.3, was imaged with the highest sensitivity and resolution to date, revealing a two-lobed morphology.more » Comparisons with previous observations of similar resolution give an upper limit of 10{sup 4} km s{sup –1} for the expansion speed of this remnant. We derive a supernova rate of <0.2 yr{sup –1} for the inner 300 pc using a model that improves on previous methods by incorporating an improved radio supernova peak luminosity distribution and by making use of multi-wavelength radio data spanning 21 yr. A star formation rate of SFR(M ≥ 5 M {sub ☉}) < 4.9 M {sub ☉} yr{sup –1} was also estimated using the standard relation between supernova and star formation rates. Our improved estimates of supernova and star formation rates are consistent with studies at other wavelengths. The results of our study point to the possible existence of a small population of undetected supernova remnants, suggesting a low rate of radio supernova production in NGC 253.« less

Redesign of a large lecture course into a small-group learning course.

PubMed

Ferreri, Stefanie P; O'Connor, Shanna K

2013-02-12

Objective. To describe the redesign of a large self-care course previously delivered in a traditional lecture format to a small-group case-based course.Design. Prereadings and study guides were used to facilitate students' independent learning prior to class. Large lecture classes were replaced with smaller group-based learning classes. This change in delivery format allowed students to spend the majority of class time conducting small-group learning activities, such as case studies to promote communication, problem solving, and interpersonal skills.Assessment. Changes in course delivery were assessed over a 2-year period by comparing students' grades and satisfaction ratings on course evaluations. A comparison of course evaluations between the class formats revealed that students were provided more opportunities to develop verbal communication skills and tackle and resolve unfamiliar problems in the revised course. The activities resulted in better overall course grades.Conclusions. Redesigning to a small-group discussion format for a self-care course can be accomplished by increasing student accountability for acquiring factual content outside the classroom. Compared with student experiences in the previous large lecture-based class, students in the smaller-class format reported a preference for working in teams and achieved significantly better academic grades with the new course format.

Optical Pattern Formation in Cold Atoms: Explaining the Red-Blue Asymmetry

NASA Astrophysics Data System (ADS)

Schmittberger, Bonnie; Gauthier, Daniel

2013-05-01

The study of pattern formation in atomic systems has provided new insight into fundamental many-body physics and low-light-level nonlinear optics. Pattern formation in cold atoms in particular is of great interest in condensed matter physics and quantum information science because atoms undergo self-organization at ultralow input powers. We recently reported the first observation of pattern formation in cold atoms but found that our results were not accurately described by any existing theoretical model of pattern formation. Previous models describing pattern formation in cold atoms predict that pattern formation should occur using both red and blue-detuned pump beams, favoring a lower threshold for blue detunings. This disagrees with our recent work, in which we only observed pattern formation with red-detuned pump beams. Previous models also assume a two-level atom, which cannot account for the cooling processes that arise when beams counterpropagate through a cold atomic vapor. We describe a new model for pattern formation that accounts for Sisyphus cooling in multi-level atoms, which gives rise to a new nonlinearity via spatial organization of the atoms. This spatial organization causes a sharp red-blue detuning asymmetry, which agrees well with our experimental observations. We gratefully acknowledge the financial support of the NSF through Grant #PHY-1206040.

Prediction of N-nitrosodimethylamine (NDMA) formation as a disinfection by-product.

PubMed

Kim, Jongo; Clevenger, Thomas E

2007-06-25

This study investigated the possibility of a statistical model application for the prediction of N-nitrosodimethylamine (NDMA) formation. The NDMA formation was studied as a function of monochloramine concentration (0.001-5mM) at fixed dimethylamine (DMA) concentrations of 0.01mM or 0.05mM. Excellent linear correlations were observed between the molar ratio of monochloramine to DMA and the NDMA formation on a log scale at pH 7 and 8. When a developed prediction equation was applied to a previously reported study, a good result was obtained. The statistical model appears to predict adequately NDMA concentrations if other NDMA precursors are excluded. Using the predictive tool, a simple and approximate calculation of NDMA formation can be obtained in drinking water systems.

Occupational Channels for Mexican Migration: New Destination Formation in a Binational Context

ERIC Educational Resources Information Center

Sanderson, Matthew; Painter, Matthew, II

2011-01-01

In the 1990s, Mexican immigration dispersed spatially, leading to the emergence of many "new destinations," in nonmetropolitan areas of the United States. Previous studies constrain the scope of the analysis to the United States, limiting our understanding of how new destinations are formed. We place new destination formation into a…

Ralstonia insidiosa serves as bridges in biofilm formation by foodborne pathogens Listeria monocytogenes, Salmonella enterica, and enterohemorrhagic Escherichia coli

USDA-ARS?s Scientific Manuscript database

Biofilm formation on abiotic surfaces in fresh produce processing facilities might play a role in foodborne outbreaks by providing protective microniches for pathogenic bacteria. Our previous study showed that a strain of Ralstonia insidiosa isolated from a fresh produce processing plant could enhan...

Using Storytelling Strategies to Improve Student Comprehension in Online Classes

ERIC Educational Resources Information Center

Powell, Rasby Marlene; Murray, Ottis

2012-01-01

Previous research shows that presenting class material in story formats can improve student learning in lecture classes. This pilot study of eight sociology classes investigates the efficacy of using storytelling as a means to improve student comprehension in online classes. Our findings show that when material is presented in story format rather…

Comparison of Difficulties and Reliabilities of Math-Completion and Multiple-Choice Item Formats.

ERIC Educational Resources Information Center

Oosterhof, Albert C.; Coats, Pamela K.

Instructors who develop classroom examinations that require students to provide a numerical response to a mathematical problem are often very concerned about the appropriateness of the multiple-choice format. The present study augments previous research relevant to this concern by comparing the difficulty and reliability of multiple-choice and…

Ionothermal Synthesis and Magnetic Studies of Novel Two-Dimensional Metal-Formate Frameworks

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

Calderone, P.; Feygenson, M.; Forster, P.M.

2011-03-21

Five novel two-dimensional frameworks containing formate-bridged metal-centered octahedra are synthesized ionothermally from two ionic liquids previously unused as solvents in hybrid synthesis, 2-hydroxyethylammonium (HEA) formate, and 1-hydroxy-3-proplyammonium (HPA) formate. Templating effects of the cation from each ionic liquid drive the formation of different structures. [NH{sub 3}C{sub 2}H{sub 4}OH]{sub 2}[M(CHO{sub 2}){sub 4}] (1: M = Co, 2: M = Ni) exhibit the same stoichiometry and connectivity as their manganese analogue (3: M = Mn), but the manganese form exhibits a different topology from 1 and 2. [NH{sub 3}C{sub 3}H6OH][M(CHO{sub 2}){sub 3}(H{sub 2}O)] (4: M = Co, 5: M = Mn) weremore » synthesized using the HPA formate ionic liquid with a metal-formate connectivity related to those of 1-3. Canted antiferromagnetic ordering occurs at low temperatures (1: T{sub N} = 7.0 K, 2: T{sub N} = 4.6 K, 3: T{sub N} = 8.0 K, 4: T{sub N} = 7.0 K, 5: T{sub N} = 9.2 K), similar to the magnetic properties previously reported for other metal-formate hybrid materials.« less

The early differentiation of Mars inferred from Hf–W chronometry

DOE PAGES

Kruijer, Thomas S.; Kleine, Thorsten; Borg, Lars E.; ...

2017-07-20

Mars probably accreted within the first 10 million years of Solar System formation and likely underwent magma ocean crystallization and crust formation soon thereafter. In this study, to assess the nature and timescales of these large-scale mantle differentiation processes we applied the short-lived 182Hf– 182W and 146Sm– 142Nd chronometers to a comprehensive suite of martian meteorites, including several shergottites, augite basalt NWA 8159, orthopyroxenite ALH 84001 and polymict breccia NWA 7034. Compared to previous studies the 182W data are significantly more precise and have been obtained for a more diverse suite of martian meteorites, ranging from samples from highly depletedmore » to highly enriched mantle and crustal sources. Our results show that martian meteorites exhibit widespread 182W/ 184W variations that are broadly correlated with 142Nd/ 144Nd, implying that silicate differentiation (and not core formation) is the main cause of the observed 182W/ 184W differences. The combined 182W– 142Nd systematics are best explained by magma ocean crystallization on Mars within ~20–25 million years after Solar System formation, followed by crust formation ~15 million years later. Finally, these ages are indistinguishable from the I–Pu–Xe age for the formation of Mars' atmosphere, indicating that the major differentiation of Mars into mantle, crust, and atmosphere occurred between 20 and 40 million years after Solar System formation and, hence, earlier than previously inferred based on Sm–Nd chronometry alone.« less

The early differentiation of Mars inferred from Hf–W chronometry

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

Kruijer, Thomas S.; Kleine, Thorsten; Borg, Lars E.

Mars probably accreted within the first 10 million years of Solar System formation and likely underwent magma ocean crystallization and crust formation soon thereafter. In this study, to assess the nature and timescales of these large-scale mantle differentiation processes we applied the short-lived 182Hf– 182W and 146Sm– 142Nd chronometers to a comprehensive suite of martian meteorites, including several shergottites, augite basalt NWA 8159, orthopyroxenite ALH 84001 and polymict breccia NWA 7034. Compared to previous studies the 182W data are significantly more precise and have been obtained for a more diverse suite of martian meteorites, ranging from samples from highly depletedmore » to highly enriched mantle and crustal sources. Our results show that martian meteorites exhibit widespread 182W/ 184W variations that are broadly correlated with 142Nd/ 144Nd, implying that silicate differentiation (and not core formation) is the main cause of the observed 182W/ 184W differences. The combined 182W– 142Nd systematics are best explained by magma ocean crystallization on Mars within ~20–25 million years after Solar System formation, followed by crust formation ~15 million years later. Finally, these ages are indistinguishable from the I–Pu–Xe age for the formation of Mars' atmosphere, indicating that the major differentiation of Mars into mantle, crust, and atmosphere occurred between 20 and 40 million years after Solar System formation and, hence, earlier than previously inferred based on Sm–Nd chronometry alone.« less

THE ROLE OF CYTOKINES IN UBD PROMOTER REGULATION AND MALLORY-DENK BODY-LIKE AGGRESOMES

PubMed Central

Oliva, Joan; Bardag-Gorce, Fawzia; Lin, Andrew; French, Barbara.A; French, Samuel W.

2010-01-01

Mallory-Denk bodies (MDBs) are found in chronic liver diseases. Previous studies showed that Diethyl-1, 4-dihydro-2,4,6,-trimethyl-3,5-pyridinedicarboxylate (DDC) induced formation of MDBs and the up regulation of UbD expression in mouse liver. UbD is a protein over expressed in hepatocellular carcinomas. It is a potential preneoplastic marker in the mouse. It is hypothesized that inflammatory cytokines play a critical role in UbD up regulation and MDB formation. TNFa and IFNg treatment of HCC cell line Hepa 1–6, induced the expression of UbD and the expression of genes coding for the immunoproteasome (LMP2, LMP7, and MECL-1 subunits). TNFa and IFNg induced the activity of the UbD promoter, using a luciferase assay. The co-treatment with TNFa and IFNg induced the activity of the UbD promoter through an Interferon Sequence Responsive Element (ISRE). In addition, long term treatment with TNFa and IFNg induced the formation of MDB-like aggresomes in Hepa 1–6 cells, which emphasizes the role of inflammation in the formation of MDBs leading to the formation of liver tumors, in the mouse. Identifying the mechanism that regulates gene expression of UbD supports the hypothesis that down regulation of UbD and the proinflammatory gene expression would prevent MDBs and HCC formation. Previous studies indicate that S-adenosylmethionine or betaine prevented IFNg induced UbD and MDB formation. PMID:20433827

The Influence of Formal and Informal Formative Pre-Service Experiences on Teacher Self-Efficacy

ERIC Educational Resources Information Center

Tuchman, Elie; Isaacs, Jenny

2011-01-01

Formal pre-service training has been shown to be effective in building teacher self-efficacy beliefs. However, the impact of other, less formal, "teacher-like" pre-service experiences on the formation of efficacy beliefs has not previously been investigated. This study examines the associations between both formal and informal formative…

Genomewide screening for genes involved in biofilm formation and miconazole susceptibility in Saccharomyces cerevisiae.

PubMed

Vandenbosch, Davy; De Canck, Evelien; Dhondt, Inne; Rigole, Petra; Nelis, Hans J; Coenye, Tom

2013-12-01

Infections related to fungal biofilms are difficult to treat due to the reduced susceptibility of sessile cells to most antifungal agents. Previous research has shown that 1-10% of sessile Candida cells survive treatment with high doses of miconazole (a fungicidal imidazole). The aim of this study was to identify genes involved in fungal biofilm formation and to unravel the mechanisms of resistance of these biofilms to miconazole. To this end, a screening of a Saccharomyces cerevisiae deletion mutant bank was carried out. Our results revealed that genes involved in peroxisomal transport and the biogenesis of the respiratory chain complex IV play an essential role in biofilm formation. On the other hand, genes involved in transcription and peroxisomal and mitochondrial organization seem to highly influence the susceptibility to miconazole of yeast biofilms. Additionally, our data confirm previous findings on genes involved in biofilm formation and in general stress responses. Our data suggest the involvement of peroxisomes in biofilm formation and miconazole resistance in fungal biofilms. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Synthesis of the Hydrogeologic Framework of the Floridan Aquifer System and Delineation of a Major Avon Park Permeable Zone in Central and Southern Florida

USGS Publications Warehouse

Reese, Ronald S.; Richardson, Emily

2008-01-01

The carbonate Floridan aquifer system of central and southern Florida (south of a latitude of about 29 degrees north) is an invaluable resource with a complex framework that has previously been mapped and managed primarily in a subregional context according to geopolitical boundaries. As interest and use of the Floridan aquifer system in this area increase, a consistent regional hydrogeologic framework is needed for effective management across these boundaries. This study synthesizes previous studies on the Floridan aquifer system and introduces a new regional hydrogeologic conceptual framework, linking physical relations between central and southern Florida and between the west and east coastal areas. The differences in hydrogeologic nomenclature and interpretation across the study area from previous studies were identified and resolved. The Floridan aquifer system consists of the Upper Floridan aquifer, middle confining unit, and Lower Floridan aquifer. This study introduces and delineates a new major, regional productive zone or subaquifer, referred to as the Avon Park permeable zone. This zone is contained within the middle confining unit and synthesizes an extensive zone that has been referred to differently in different parts of the study area in previous studies. The name of this zone derives from the description of this zone as the ?Avon Park highly permeable zone? in west-central Florida in a previous study. Additionally, this zone has been identified previously in southeastern Florida as the ?middle Floridan aquifer.? An approximately correlative or approximate time-stratigraphic framework was developed and was used to provide guidance in the identification and determination of aquifers, subaquifers, and confining units within the Floridan aquifer system and to determine their structural relations. Two stratigraphic marker horizons within the Floridan aquifer system and a marker unit near the top of the aquifer system were delineated or mapped. The marker horizons are correlative points in the stratigraphic section rather than a unit with upper and lower boundaries. The two marker horizons and the marker unit originated from previous studies, wherein they were based on lithology and correlation of geophysical log signatures observed in boreholes. The depths of these marker horizons and the marker unit were extended throughout the study area by correlation of natural gamma-ray logs between wells. The Floridan aquifer system includes, in ascending order, the upper part of the Cedar Keys Formation, Oldsmar Formation, Avon Park Formation, Ocala Limestone, Suwannee Limestone, and in some areas the lower part of the Hawthorn Group. The first marker horizon is in the lower part of the aquifer system near the top of the Oldsmar Formation and is associated with the top of distinctive glauconitic limestone beds that are present in some regions; the second marker horizon is near the middle of the aquifer system in the middle part of the Avon Park Formation. The marker unit lies at the top of a basal unit in the Hawthorn Group and provides a stratigraphic constraint for the top of the Floridan aquifer system. The marker horizons do not have distinguishing lithologic characteristics or a characteristic gamma-ray log pattern in all areas but are still thought to be valid because of correlation of the entire section and correlation of all sufficiently deep wells with gamma-ray logs. The Avon Park permeable zone is contained entirely within the Avon Park Formation; its position within the section is either near the middle Avon Park marker horizon or within a thick part of the section that extends several hundred feet above the marker horizon. This subaquifer is present over most of the study area and characteristically consists of thick units of dolostone and interbedded limestone, and limestone in its upper part. Permeability is primarily associated with fracturing. This subaquifer is well developed in west-cen

Stratigraphic framework and regional subsurface geology of upper Cretaceous through lower Eocene rocks in Wind River basin, Wyoming

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

Hogle, D.G.; Jones, R.W.

1989-03-01

A detailed stratigraphic study of over 6000 m of Upper Cretaceous through lower Eocene sedimentary rocks in the Wind River basin. Wyoming, has refined and expanded previous work and conclusions. A much larger data base than previously available was assembled to include a correlation net of 325 geophysical well logs, 36 drill holes with palynological age dates, lithology logs of drill hoes, and limited surface exposures. The most significant results and conclusions from this study are summarized below. (1) The lower part of the Mesaverde Formation intertongues with marine sandstones and shales of the upper Cody Shale to the eastmore » and with marine sandstones of the lower Mesaverde Formation in the Big Horn basin to the north. (2) An unconformity between the Mesaverde and Fort Union Formations in the southwestern part of the basin can be traced into the subsurface. (3) During the latest Cretaceous and Paleocene, over 2100 m of Lance Formation and over 2700 m of Fort Union Formation were deposited in the northeastern part of the basin. Ponding during the Paleocene is demonstrated by correlation and subsurface mapping of over 900 m of shale and siltstone in the Waltman Shale Member of the Fort Union Formation. (4) The Lance and Fort Union Formations can be mapped in the subsurface throughout much of the basin. The Lance Formation pinches out in the western part of the basin. (5) Coal beds can be traced for short distances in the subsurface; coal bed occurrence is documented for the Mesaverde, lower Fort Union, and Meeteetse Formations in the southwestern, northern and central, and northwestern parts of the basin, respectively.« less

Reconnection–Condensation Model for Solar Prominence Formation

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

Kaneko, Takafumi; Yokoyama, Takaaki, E-mail: kaneko@isee.nagoya-u.ac.jp

We propose a reconnection–condensation model in which topological change in a coronal magnetic field via reconnection triggers radiative condensation, thereby resulting in prominence formation. Previous observational studies have suggested that reconnection at a polarity inversion line of a coronal arcade field creates a flux rope that can sustain a prominence; however, they did not explain the origin of cool dense plasmas of prominences. Using three-dimensional magnetohydrodynamic simulations, including anisotropic nonlinear thermal conduction and optically thin radiative cooling, we demonstrate that reconnection can lead not only to flux rope formation but also to radiative condensation under a certain condition. In ourmore » model, this condition is described by the Field length, which is defined as the scale length for thermal balance between radiative cooling and thermal conduction. This critical condition depends weakly on the artificial background heating. The extreme ultraviolet emissions synthesized with our simulation results have good agreement with observational signatures reported in previous studies.« less

Role of the Simian Virus 5 Fusion Protein N-Terminal Coiled-Coil Domain in Folding and Promotion of Membrane Fusion

PubMed Central

West, Dava S.; Sheehan, Michael S.; Segeleon, Patrick K.; Dutch, Rebecca Ellis

2005-01-01

Formation of a six-helix bundle comprised of three C-terminal heptad repeat regions in antiparallel orientation in the grooves of an N-terminal coiled-coil is critical for promotion of membrane fusion by paramyxovirus fusion (F) proteins. We have examined the effect of mutations in four residues of the N-terminal heptad repeat in the simian virus 5 (SV5) F protein on protein folding, transport, and fusogenic activity. The residues chosen have previously been shown from study of isolated peptides to have differing effects on stability of the N-terminal coiled-coil and six-helix bundle (R. E. Dutch, G. P. Leser, and R. A. Lamb, Virology 254:147-159, 1999). The mutant V154M showed reduced proteolytic cleavage and surface expression, indicating a defect in intracellular transport, though this mutation had no effect when studied in isolated peptides. The mutation I137M, previously shown to lower thermostability of the six-helix bundle, resulted in an F protein which was properly processed and transported to the cell surface but which had reduced fusogenic activity. Finally, mutations at L140M and L161M, previously shown to disrupt α-helix formation of isolated N-1 peptides but not to affect six-helix bundle formation, resulted in F proteins that were properly processed. Interestingly, the L161M mutant showed increased syncytium formation and promoted fusion at lower temperatures than the wild-type F protein. These results indicate that interactions separate from formation of an N-terminal coiled-coil or six-helix bundle are important in the initial folding and transport of the SV5 F protein and that mutations that destabilize the N-terminal coiled-coil can result in stimulation of membrane fusion. PMID:15650180

Formative Evaluation of MyFit: A Curriculum to Promote Self-Regulation of Physical Activity among Middle School Students

ERIC Educational Resources Information Center

Grim, Melissa; Petosa, Rick; Hortz, Brian; Hunt, Laura

2013-01-01

Background: Previous interventions to increase physical activity among middle school students have not produced long-term results. Often, students lack the self-regulation skills needed to support long-term adherence to physical activity. Purpose: The purpose of this study was to conduct a formative evaluation of a self-regulation based physical…

Photochemically assisted fast abiotic oxidation of manganese and formation of δ-MnO 2 nanosheets in nitrate solution

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

Jung, Haesung; Chadha, Tandeep S.; Kim, Doyoon

This study introduces a new and previously unconsidered fast abiotic formation of Mn(IV) oxides. We report photochemically assisted fast abiotic oxidation of Mn 2+ (aq) to Mn(IV) (s) by superoxide radicals generated from nitrate photolysis. This photochemical pathway generates randomly stacked layered birnessite (δ-MnO 2) nanosheets.

Formation Flying for Distributed InSAR

NASA Technical Reports Server (NTRS)

Scharf, Daniel P.; Murray, Emmanuell A.; Ploen, Scott R.; Gromov, Konstantin G.; Chen, Curtis W.

2006-01-01

We consider two spacecraft flying in formation to create interferometric synthetic aperture radar (InSAR). Several candidate orbits for such in InSar formation have been previously determined based on radar performance and Keplerian orbital dynamics. However, with out active control, disturbance-induced drift can degrade radar performance and (in the worst case) cause a collision. This study evaluates the feasibility of operating the InSAR spacecraft as a formation, that is, with inner-spacecraft sensing and control. We describe the candidate InSAR orbits, design formation guidance and control architectures and algorithms, and report the (Delta)(nu) and control acceleration requirements for the candidate orbits for several tracking performance levels. As part of determining formation requirements, a formation guidance algorithm called Command Virtual Structure is introduced that can reduce the (Delta)(nu) requirements compared to standard Leader/Follower formation approaches.

Condensation Temperature in Non-Equilibrium Condensation.

NASA Astrophysics Data System (ADS)

Tanaka, K. K.; Tanaka, H.; Nakazawa, K.

1999-09-01

In investigation of the origins of the presolar grains, it is important to clear the formation process of grains in ejecta of AGB stars or supernovae, where most presolar grains are suggested to be formed. The grain formation has been investigated based on the classical nucleation theory in many previous studies. On the other hand it has been pointed out that the classical nucleation rate is significantly different from that obtained by experiments, and should not be applied to grain formation in astrophysical environments (Donn and Nuth, 1985, ApJ 288, 187-190). Recently Dillmann and Meier (1991, J. Chem. Phys. 94, 3872-3884) proposed new semi-phenomological nucleation model, which achieved excellent agreements with experiments. In this study we applied the nucleation rate in the semi-phenomological model to the grain formation in astrophysical environment in order to make it clear how the grain formation changes due to the new nucleation rate. For various parameters determined by surface energy of grain and cooling time of vapor, we solved equations describing the grain formation. From the comparison between the results obtained by new nucleation rate and that by classical one we found that there is no significant difference in grain number density and grain size, but the condensation temperature is considerably different from the previous one. For example in carbon rich AGB star the condensation temperature of graphite is lower than that obtained by classical one by a few hundreds Kelvin: this means the condensation temperature is lower than the equilibrium condensation temperature by about 500 Kelvin. Furthermore we investigated the condensation of vapor in which grain impurities are already present. We obtained the condition for formation of core-mantle type grains. Our obtained condition would give constraint on the formation of core-mantle type presolar grains.

A possible formation scenario for dwarf spheroidal galaxies - III. Adding star formation histories to the fiducial model

NASA Astrophysics Data System (ADS)

Alarcón Jara, A. G.; Fellhauer, M.; Matus Carrillo, D. R.; Assmann, P.; Urrutia Zapata, F.; Hazeldine, J.; Aravena, C. A.

2018-02-01

Dwarf spheroidal galaxies are regarded as the basic building blocks in the formation of larger galaxies and are the most dark matter dominated systems in the Universe, known so far. There are several models that attempt to explain their formation and evolution, but they have problems modelling the formation of isolated dwarf spheroidal galaxies. Here, we will explain a possible formation scenario in which star clusters form inside the dark matter halo of a dwarf spheroidal galaxy. These star clusters suffer from low star formation efficiency and dissolve while orbiting inside the dark matter halo. Thereby, they build the faint luminous components that we observe in dwarf spheroidal galaxies. In this paper, we study this model by adding different star formation histories to the simulations and compare the results with our previous work and observational data to show that we can explain the formation of dwarf spheroidal galaxies.

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

McCollum, L.B.; Buchanan, J.P.; McCollum, M.B.

The Antler orogeny is a textbook example of a Paleozoic mountain building and crustal shortening event in western North America. A relatively complex geologic history of the type Antler at Battle Mountain, Nevada, is interpreted as distinct thrust plates of Lower Cambrian Scott Canyon Formation, Upper Cambrian Harmony Sandstone, and Ordovician Valmy Formation, overlain unconformably by the Middle Pennsylvanian Battle Formation. Mississippian crustal deformation and emplacement of the Roberts Mountain thrust have previously been thought to characterize the Antler orogen. Detailed sedimentology studies of the Scott Canyon and Harmony, and the relationship with the overlying Battle Formation at the typemore » section of the Antler orogeny, cast doubt on the previously accepted geologic history. The Scott Canyon is an interbedded sequence of pillow basalts, Late Devonian radiolarian cherts, and mudstone debris flows with numerous limestone olistoliths, many containing undescribed archaeocyathid fauna. The contact of the Harmony with the Battle Formation appears channeled, but otherwise conformable, and the Battle has been interpreted as an alluvial fan facies. The paleoenvironmental interpretation of these sediments is that the Scott Canyon was deposited upon a Late Devonian active continental margin setting, with prograding fan deposits of the Harmony Sandstone, overlain by Middle Pennsylvanian fanglomerates of the Battle Formation. This conformable sequence appears to preclude any major uplift within the type Antler orogen.« less

Respective Role of the Dorsal Hippocampus and the Entorhinal Cortex during the Recombination of Previously Learned Olfactory-Tactile Associations in the Rat

ERIC Educational Resources Information Center

Boisselier, Lise; Ferry, Barbara; Gervais, Rémi

2017-01-01

The hippocampal formation has been extensively described as a key component for object recognition in conjunction with place and context. The present study aimed at describing neural mechanisms in the hippocampal formation that support olfactory-tactile (OT) object discrimination in a task where space and context were not taken into account. The…

Lessons Learnt from Applying Action Research to Support Strategy Formation Processes in Long-Term Care Networks

ERIC Educational Resources Information Center

Cramer, Hendrik; Dewulf, Geert; Voordijk, Hans

2015-01-01

This study demonstrates how action research (AR) that is aimed at scaling-up experiments can be applied to support a strategy formation process (SFP) in a subsidized long-term care network. Previous research has developed numerous AR frameworks to support experiments in various domains, but has failed to explain how to apply AR and action learning…

Web-based vs. traditional classroom instruction in gerontology: a pilot study.

PubMed

Gallagher, Judith E; Dobrosielski-Vergona, Kathleen A; Wingard, Robin G; Williams, Theresa M

2005-01-01

Numerous studies have documented comparable outcomes from Web-based and traditional classroom instruction. However, there is a paucity of literature comparing these two delivery formats for gerontology courses in dental hygiene curricula. This study examines the effectiveness of alternative methods of course delivery by comparing student profiles and instructional outcomes from a dental hygiene gerontology course offered both on the Web and in a traditional classroom setting. Questionnaires were sent to both groups of students completing the course. The instrument was designed to establish profiles of the participating students. The data collected included familiarity with Web-based instruction, extent of prior computer training, previous interaction with the elderly, and student evaluations of course effectiveness. Traditional instructional outcomes from evaluated course work were compared, as were post-course exam outcomes that assessed retention of course information six months after course completion. The statistical significance of these data was determined using Statistical Package for Social Scientists software (SPSS, Inc., version 12.0, Chicago, IL). A comparison of student characteristics enrolled in the two course formats revealed marked differences. The Web-based group (n=12) included dental hygiene students (67%) and other health care providers (25%). All participants in the traditional classroom format (n=32) were dental hygiene students. Half of the Web-based respondents were over 25 years of age, and the majority (n=8) had previously taken an online course. The majority of traditional classroom students were 25 years of age or younger (n=21) and had never taken a Web-based course (n=20). Statistically significant differences in instructional outcomes were observed between students enrolled in these two formats. Student retention of course material six months after completion of the course was greater in the Web-based format. Students selecting a Web-based course format demonstrated greater motivation and learning success based on final course grades, completion of assignments, and knowledge retention over time. Age, previous experience with online courses, and selection of teaching mode are factors that may confound course delivery method to influence instructional outcomes in a gerontology course within a dental hygiene curriculum.

The Epidemiology of Anti-Sperm Antibodies Among Couples with Unexplained Infertility in North West Bank, Palestine.

PubMed

Yasin, Anas Lotfi; Yasin, Ahmad Lotfi; Basha, Walid Salim

2016-03-01

Anti sperm antibodies (ASA) can present in serum and semen and they may lead to impair the sperms function leading to infertility. The precise mechanism of generation of these antibodies is yet to be discovered. This study was performed to determine the prevalence of anti-sperm antibodies (ASA) in patients with unexplained infertility. The study was initiated also to explore the possible factors that may associate with ASA formation and how ASA status is associated with pregnancy rates after going with in vitro fertilization - intracytoplasmic sperm injection (IVF-ICSI). A cross-sectional study was conducted on 42 normal infertile couples consulting Razan Medical Center for Infertility & I.V.F. in Nablus, Palestine, from December 2012 - March 2013. Serum levels of immunoglobulins G (IgG) ASA were measured in participants (males and females) using enzyme-linked immunosorbent assay (ELISA). In addition, participants also filled a questionnaire about the presence of previous varicocele repair, inguinal hernia repair, orchitis, testicular trauma and vasectomy reversal among males and severe coitus bleeding and coitus during menses or puerperium among females. Couples were also asked about previous IVF-ICSI procedures and the outcome of the procedure in terms of either they got pregnant or not. Data was analysed using SPSS software. The prevalence of ASA was 14.3% (6/42) among all couples, 9.5% (4/42) among males and 4.8% (2/42) among females. There was no significant relationship between previous varicocele repair, previous inguinal hernia repair, or orchitis and formation of ASA (p value =0.64, 0.56, and 0.26 respectively). Previous trauma, vasovasostomy, severe coitus bleeding and coitus during menses or puerperium were not observed in any of the study sample. ASA did not seem to affect the outcome of IVF-ICSI (p-value =0.54). Prevalence of ASA in infertile couples in the north part of Palestine is similar to that obtained worldwide. ASA formation does not relate to any of the studied risk factors and does not seem to associate with pregnancy rate after IVF-ICSI. We recommend further studies using a larger sample size and including all parts of Palestine in order to generalize the obtained results.

New particle formation in the sulfuric acid-dimethylamine-water system: reevaluation of CLOUD chamber measurements and comparison to an aerosol nucleation and growth model

NASA Astrophysics Data System (ADS)

Kürten, Andreas; Li, Chenxi; Bianchi, Federico; Curtius, Joachim; Dias, António; Donahue, Neil M.; Duplissy, Jonathan; Flagan, Richard C.; Hakala, Jani; Jokinen, Tuija; Kirkby, Jasper; Kulmala, Markku; Laaksonen, Ari; Lehtipalo, Katrianne; Makhmutov, Vladimir; Onnela, Antti; Rissanen, Matti P.; Simon, Mario; Sipilä, Mikko; Stozhkov, Yuri; Tröstl, Jasmin; Ye, Penglin; McMurry, Peter H.

2018-01-01

A recent CLOUD (Cosmics Leaving OUtdoor Droplets) chamber study showed that sulfuric acid and dimethylamine produce new aerosols very efficiently and yield particle formation rates that are compatible with boundary layer observations. These previously published new particle formation (NPF) rates are reanalyzed in the present study with an advanced method. The results show that the NPF rates at 1.7 nm are more than a factor of 10 faster than previously published due to earlier approximations in correcting particle measurements made at a larger detection threshold. The revised NPF rates agree almost perfectly with calculated rates from a kinetic aerosol model at different sizes (1.7 and 4.3 nm mobility diameter). In addition, modeled and measured size distributions show good agreement over a wide range of sizes (up to ca. 30 nm). Furthermore, the aerosol model is modified such that evaporation rates for some clusters can be taken into account; these evaporation rates were previously published from a flow tube study. Using this model, the findings from the present study and the flow tube experiment can be brought into good agreement for the high base-to-acid ratios (˜ 100) relevant for this study. This confirms that nucleation proceeds at rates that are compatible with collision-controlled (a.k.a. kinetically controlled) NPF for the conditions during the CLOUD7 experiment (278 K, 38 % relative humidity, sulfuric acid concentration between 1 × 106 and 3 × 107 cm-3, and dimethylamine mixing ratio of ˜ 40 pptv, i.e., 1 × 109 cm-3).

Influence of phase inversion on the formation and stability of one-step multiple emulsions.

PubMed

Morais, Jacqueline M; Rocha-Filho, Pedro A; Burgess, Diane J

2009-07-21

A novel method of preparation of water-in-oil-in-micelle-containing water (W/O/W(m)) multiple emulsions using the one-step emulsification method is reported. These multiple emulsions were normal (not temporary) and stable over a 60 day test period. Previously, reported multiple emulsion by the one-step method were abnormal systems that formed at the inversion point of simple emulsion (where there is an incompatibility in the Ostwald and Bancroft theories, and typically these are O/W/O systems). Pseudoternary phase diagrams and bidimensional process-composition (phase inversion) maps were constructed to assist in process and composition optimization. The surfactants used were PEG40 hydrogenated castor oil and sorbitan oleate, and mineral and vegetables oils were investigated. Physicochemical characterization studies showed experimentally, for the first time, the significance of the ultralow surface tension point on multiple emulsion formation by one-step via phase inversion processes. Although the significance of ultralow surface tension has been speculated previously, to the best of our knowledge, this is the first experimental confirmation. The multiple emulsion system reported here was dependent not only upon the emulsification temperature, but also upon the component ratios, therefore both the emulsion phase inversion and the phase inversion temperature were considered to fully explain their formation. Accordingly, it is hypothesized that the formation of these normal multiple emulsions is not a result of a temporary incompatibility (at the inversion point) during simple emulsion preparation, as previously reported. Rather, these normal W/O/W(m) emulsions are a result of the simultaneous occurrence of catastrophic and transitional phase inversion processes. The formation of the primary emulsions (W/O) is in accordance with the Ostwald theory ,and the formation of the multiple emulsions (W/O/W(m)) is in agreement with the Bancroft theory.

Use of a Land Streamer System to Image the Potomac Formation in Northern Delaware

NASA Astrophysics Data System (ADS)

Velez, C. C.; McLaughlin, P. P.; McGeary, S.; Sargent, S. L.

2008-12-01

A land streamer system, an alternative to conventional seismic acquisition equipment for collecting large amounts of seismic reflection data in urbanized and semi-urbanized areas, was used to collect a network of high-resolution seismic reflection data in northern Delaware. The principal objective of this work is to image the distribution and geometry of sand bodies in the Cretaceous (Aptian to Cenomanian) non-marine deposits of the Potomac Formation. The Potomac Formation includes the most important confined aquifers in the Coastal Plain of northern Delaware. Previous studies indicate these deposits onlap Paleozoic basement at depths from 115 m to 400 m in the study area and are truncated by an unconformity. Previous descriptions of sedimentary facies from nearby cores and geophysical logs indicate that the Potomac Formation is a predominantly fine-grained alluvial unit with laterally discontinuous fluvial sand bodies, resulting in a "labyrinth style heterogeneity" for aquifer facies. The 20-km seismic dataset collected for this study indicates that land-streamer seismic methods can be used in this area to image the subsurface geology as shallow as 18 m and as deep as the basement at 315 m. The theoretical quarter wavelength of the seismic dataset suggests a resolution of 2 to 4 m, which is sufficient to resolve aquifer sands in the Potomac Formation ranging from 10 to 20 m thick. Final processed seismic sections will be integrated with geophysical logs and core data to provide a robust 2-D dataset that will allow assessment of current concepts for facies and correlations in the Potomac Formation, thus benefiting understanding of critical ground-water resources.

Amyloid-β annular protofibrils evade fibrillar fate in Alzheimer disease brain.

PubMed

Lasagna-Reeves, Cristian A; Glabe, Charles G; Kayed, Rakez

2011-06-24

Annular protofibrils (APFs) represent a new and distinct class of amyloid structures formed by disease-associated proteins. In vitro, these pore-like structures have been implicated in membrane permeabilization and ion homeostasis via pore formation. Still, evidence for their formation and relevance in vivo is lacking. Herein, we report that APFs are in a distinct pathway from fibril formation in vitro and in vivo. In human Alzheimer disease brain samples, amyloid-β APFs were associated with diffuse plaques, but not compact plaques; moreover, we show the formation of intracellular APFs. Our results together with previous studies suggest that the prevention of amyloid-β annular protofibril formation could be a relevant target for the prevention of amyloid-β toxicity in Alzheimer disease.

Effects of Low-Dose Amoxicillin on Staphylococcus aureus USA300 Biofilms

PubMed Central

Mlynek, Kevin D.; Callahan, Mary T.; Shimkevitch, Anton V.; Farmer, Jackson T.; Endres, Jennifer L.; Marchand, Mélodie; Bayles, Kenneth W.; Horswill, Alexander R.

2016-01-01

Previous studies showed that sub-MIC levels of β-lactam antibiotics stimulate biofilm formation in most methicillin-resistant Staphylococcus aureus (MRSA) strains. Here, we investigated this process by measuring the effects of sub-MIC amoxicillin on biofilm formation by the epidemic community-associated MRSA strain USA300. We found that sub-MIC amoxicillin increased the ability of USA300 cells to attach to surfaces and form biofilms under both static and flow conditions. We also found that USA300 biofilms cultured in sub-MIC amoxicillin were thicker, contained more pillar and channel structures, and were less porous than biofilms cultured without antibiotic. Biofilm formation in sub-MIC amoxicillin correlated with the production of extracellular DNA (eDNA). However, eDNA released by amoxicillin-induced cell lysis alone was evidently not sufficient to stimulate biofilm. Sub-MIC levels of two other cell wall-active agents with different mechanisms of action—d-cycloserine and fosfomycin—also stimulated eDNA-dependent biofilm, suggesting that biofilm formation may be a mechanistic adaptation to cell wall stress. Screening a USA300 mariner transposon library for mutants deficient in biofilm formation in sub-MIC amoxicillin identified numerous known mediators of S. aureus β-lactam resistance and biofilm formation, as well as novel genes not previously associated with these phenotypes. Our results link cell wall stress and biofilm formation in MRSA and suggest that eDNA-dependent biofilm formation by strain USA300 in low-dose amoxicillin is an inducible phenotype that can be used to identify novel genes impacting MRSA β-lactam resistance and biofilm formation. PMID:26856828

Updating histological data on crown initiation and crown completion ages in southern Africans.

PubMed

Reid, Donald J; Guatelli-Steinberg, Debbie

2017-04-01

To update histological data on crown initiation and completion ages in southern Africans. To evaluate implications of these data for studies that: (a) rely on these data to time linear enamel hypoplasias (LEHs), or, (b) use these data for comparison to fossil hominins. Initiation ages were calculated on 67 histological sections from southern Africans, with sample sizes ranging from one to 11 per tooth type. Crown completion ages for southern Africans were calculated in two ways. First, actual derived initiation ages were added to crown formation times for each histological section to obtain direct information on the crown completion ages of individuals. Second, average initiation ages from this study were added to average crown formation times of southern Africans from the Reid and coworkers previous studies that were based on larger samples. For earlier-initiating tooth types (all anterior teeth and first molars), there is little difference in ages of initiation and crown completion between this and previous studies. Differences increase as a function of initiation age, such that the greatest differences between this and previous studies for both initiation and crown completion ages are for the second and third molars. This study documents variation in initiation ages, particularly for later-initiating tooth types. It upholds the use of previously published histological aging charts for LEHs on anterior teeth. However, this study finds that ages of crown initiation and completion in second and third molars for this southern African sample are earlier than previously estimated. These earlier ages reduce differences between modern humans and fossil hominins for these developmental events in second and third molars. © 2017 Wiley Periodicals, Inc.

Age Differences in the Contribution of Recollection and Familiarity to False-Memory Formation: A New Paradigm to Examine Developmental Reversals

ERIC Educational Resources Information Center

Lyons, Kristen E.; Ghetti, Simona; Cornoldi, Cesare

2010-01-01

Using a new method for studying the development of false-memory formation, we examined developmental differences in the rates at which 6-, 7-, 9-, 10-, and 18-year-olds made two types of memory errors: backward causal-inference errors (i.e. falsely remembering having viewed the non-viewed cause of a previously viewed effect), and gap-filling…

The Tumor Suppressor Actions of the Vitamin D Receptor in Skin

DTIC Science & Technology

2014-10-01

induced tumor formation. In previous studies we determined that the hedgehog (HH) and wnt/β-catenin pathways were activated in the skin of VDR null...SUBJECT TERMS epidermal tumors, keratinocytes, vitamin D receptor, sonic hedgehog , β-catenin, UVB 16. SECURITY CLASSIFICATION OF: 17. LIMITATION...epidermal tumor formation by blocking the β-catenin and hedgehog pathways, key pathways in keratinocyte proliferation that if left unchecked lead to

The effect of solution nonideality on modeling transmembrane water transport and diffusion-limited intracellular ice formation during cryopreservation

NASA Astrophysics Data System (ADS)

Zhao, Gang; Takamatsu, Hiroshi; He, Xiaoming

2014-04-01

A new model was developed to predict transmembrane water transport and diffusion-limited ice formation in cells during freezing without the ideal-solution assumption that has been used in previous models. The model was applied to predict cell dehydration and intracellular ice formation (IIF) during cryopreservation of mouse oocytes and bovine carotid artery endothelial cells in aqueous sodium chloride (NaCl) solution with glycerol as the cryoprotectant or cryoprotective agent. A comparison of the predictions between the present model and the previously reported models indicated that the ideal-solution assumption results in under-prediction of the amount of intracellular ice at slow cooling rates (<50 K/min). In addition, the lower critical cooling rates for IIF that is lethal to cells predicted by the present model were much lower than those estimated with the ideal-solution assumption. This study represents the first investigation on how accounting for solution nonideality in modeling water transport across the cell membrane could affect the prediction of diffusion-limited ice formation in biological cells during freezing. Future studies are warranted to look at other assumptions alongside nonideality to further develop the model as a useful tool for optimizing the protocol of cell cryopreservation for practical applications.

The effect of solution nonideality on modeling transmembrane water transport and diffusion-limited intracellular ice formation during cryopreservation.

PubMed

Zhao, Gang; Takamatsu, Hiroshi; He, Xiaoming

2014-04-14

A new model was developed to predict transmembrane water transport and diffusion-limited ice formation in cells during freezing without the ideal-solution assumption that has been used in previous models. The model was applied to predict cell dehydration and intracellular ice formation (IIF) during cryopreservation of mouse oocytes and bovine carotid artery endothelial cells in aqueous sodium chloride (NaCl) solution with glycerol as the cryoprotectant or cryoprotective agent. A comparison of the predictions between the present model and the previously reported models indicated that the ideal-solution assumption results in under-prediction of the amount of intracellular ice at slow cooling rates (<50 K/min). In addition, the lower critical cooling rates for IIF that is lethal to cells predicted by the present model were much lower than those estimated with the ideal-solution assumption. This study represents the first investigation on how accounting for solution nonideality in modeling water transport across the cell membrane could affect the prediction of diffusion-limited ice formation in biological cells during freezing. Future studies are warranted to look at other assumptions alongside nonideality to further develop the model as a useful tool for optimizing the protocol of cell cryopreservation for practical applications.

Petrologic and isotopic data from the Cretaceous (Campanian) Blackhawk Formation and Star Point Sandstone (Mesaverde Group), Wasatch Plateau, Utah

USGS Publications Warehouse

Fishman, Neil S.; Turner, Christine E.; Peterson, Fred

2013-01-01

The presence of discrete minerals associated with coal—whether (1) detrital or authigenic constituents of the coals or in thin mudstone or siltstone units interbedded with coals, or (2) authigenic phases that formed along cleats—might influence its utilization as an energy resource. The build-up of sintered ash deposits on the surfaces of heat exchangers in coal-fired power plants, due to the alteration of minerals during combustion of the coal, can seriously affect the functioning of the boiler and enhance corrosion of combustion equipment. In particular, the presence of sodium in coals has been considered a key factor in the fouling of boilers; however, other elements (such as calcium or magnesium) and the amount of discrete minerals burned with coal can also play a significant role in the inefficiency of and damage to boilers. Previous studies of the quality of coals in the Cretaceous (Campanian) Blackhawk Formation of the Wasatch Plateau, Utah, revealed that the sodium content of the coals varied across the region. To better understand the origin and distribution of sodium in these coals, petrologic studies were undertaken within a sedimentological framework to evaluate the timing and geochemical constraints on the emplacement of sodium-bearing minerals, particularly analcime, which previously had been identified in coals in the Blackhawk Formation. Further, the study was broadened to include not just coals in the Blackhawk Formation from various localities across the Wasatch Plateau, but also sandstones interbedded with the coals as well as sandstones in the underlying Star Point Sandstone. The alteration history of the sandstones in both formations was considered a key component of this study because it records the nature and timing of fluids passing through them and the associated precipitation of sodium-bearing minerals; thus, the alteration history could place constraints on the distribution and timing of sodium mineralization in the interbedded or overlying Blackhawk coals. Although some preliminary results were previously presented at scientific meetings, the petrologic and geochemical data have not been fully compiled and reported. The purpose of this report is to present the methods of data acquisition and the results of petrologic and isotopic analyses on coal and sandstone samples from the Blackhawk Formation as well as sandstones of the underlying Star Point Sandstone.

Dopamine D1 receptor activation leads to object recognition memory in a coral reef fish.

PubMed

Hamilton, Trevor J; Tresguerres, Martin; Kline, David I

2017-07-01

Object recognition memory is the ability to identify previously seen objects and is an adaptive mechanism that increases survival for many species throughout the animal kingdom. Previously believed to be possessed by only the highest order mammals, it is now becoming clear that fish are also capable of this type of memory formation. Similar to the mammalian hippocampus, the dorsolateral pallium regulates distinct memory processes and is modulated by neurotransmitters such as dopamine. Caribbean bicolour damselfish ( Stegastes partitus ) live in complex environments dominated by coral reef structures and thus likely possess many types of complex memory abilities including object recognition. This study used a novel object recognition test in which fish were first presented two identical objects, then after a retention interval of 10 min with no objects, the fish were presented with a novel object and one of the objects they had previously encountered in the first trial. We demonstrate that the dopamine D 1 -receptor agonist (SKF 38393) induces the formation of object recognition memories in these fish. Thus, our results suggest that dopamine-receptor mediated enhancement of spatial memory formation in fish represents an evolutionarily conserved mechanism in vertebrates. © 2017 The Author(s).

Formation and emission of large furans and oxygenated hydrocarbons from flames

PubMed Central

Johansson, K. Olof; Dillstrom, Tyler; Monti, Matteo; El Gabaly, Farid; Campbell, Matthew F.; Schrader, Paul E.; Popolan-Vaida, Denisia M.; Richards-Henderson, Nicole K.; Wilson, Kevin R.; Violi, Angela; Michelsen, Hope A.

2016-01-01

Many oxygenated hydrocarbon species formed during combustion, such as furans, are highly toxic and detrimental to human health and the environment. These species may also increase the hygroscopicity of soot and strongly influence the effects of soot on regional and global climate. However, large furans and associated oxygenated species have not previously been observed in flames, and their formation mechanism and interplay with polycyclic aromatic hydrocarbons (PAHs) are poorly understood. We report on a synergistic computational and experimental effort that elucidates the formation of oxygen-embedded compounds, such as furans and other oxygenated hydrocarbons, during the combustion of hydrocarbon fuels. We used ab initio and probabilistic computational techniques to identify low-barrier reaction mechanisms for the formation of large furans and other oxygenated hydrocarbons. We used vacuum-UV photoionization aerosol mass spectrometry and X-ray photoelectron spectroscopy to confirm these predictions. We show that furans are produced in the high-temperature regions of hydrocarbon flames, where they remarkably survive and become the main functional group of oxygenates that incorporate into incipient soot. In controlled flame studies, we discovered ∼100 oxygenated species previously unaccounted for. We found that large alcohols and enols act as precursors to furans, leading to incorporation of oxygen into the carbon skeletons of PAHs. Our results depart dramatically from the crude chemistry of carbon- and oxygen-containing molecules previously considered in hydrocarbon formation and oxidation models and spearhead the emerging understanding of the oxidation chemistry that is critical, for example, to control emissions of toxic and carcinogenic combustion by-products, which also greatly affect global warming. PMID:27410045

Formation and emission of large furans and oxygenated hydrocarbons from flames.

PubMed

Johansson, K Olof; Dillstrom, Tyler; Monti, Matteo; El Gabaly, Farid; Campbell, Matthew F; Schrader, Paul E; Popolan-Vaida, Denisia M; Richards-Henderson, Nicole K; Wilson, Kevin R; Violi, Angela; Michelsen, Hope A

2016-07-26

Many oxygenated hydrocarbon species formed during combustion, such as furans, are highly toxic and detrimental to human health and the environment. These species may also increase the hygroscopicity of soot and strongly influence the effects of soot on regional and global climate. However, large furans and associated oxygenated species have not previously been observed in flames, and their formation mechanism and interplay with polycyclic aromatic hydrocarbons (PAHs) are poorly understood. We report on a synergistic computational and experimental effort that elucidates the formation of oxygen-embedded compounds, such as furans and other oxygenated hydrocarbons, during the combustion of hydrocarbon fuels. We used ab initio and probabilistic computational techniques to identify low-barrier reaction mechanisms for the formation of large furans and other oxygenated hydrocarbons. We used vacuum-UV photoionization aerosol mass spectrometry and X-ray photoelectron spectroscopy to confirm these predictions. We show that furans are produced in the high-temperature regions of hydrocarbon flames, where they remarkably survive and become the main functional group of oxygenates that incorporate into incipient soot. In controlled flame studies, we discovered ∼100 oxygenated species previously unaccounted for. We found that large alcohols and enols act as precursors to furans, leading to incorporation of oxygen into the carbon skeletons of PAHs. Our results depart dramatically from the crude chemistry of carbon- and oxygen-containing molecules previously considered in hydrocarbon formation and oxidation models and spearhead the emerging understanding of the oxidation chemistry that is critical, for example, to control emissions of toxic and carcinogenic combustion by-products, which also greatly affect global warming.

Formation and emission of large furans and oxygenated hydrocarbons from flames

DOE PAGES

Johansson, K. Olof; Dillstrom, Tyler; Monti, Matteo; ...

2016-07-07

Many oxygenated hydrocarbon species formed during combustion, such as furans, are highly toxic and detrimental to human health and the environment. These species may also increase the hygroscopicity of soot and strongly influence the effects of soot on regional and global climate. However, large furans and associated oxygenated species have not previously been observed in flames, and their formation mechanism and interplay with polycyclic aromatic hydrocarbons (PAHs) are poorly understood. We report on a synergistic computational and experimental effort that elucidates the formation of oxygen-embedded compounds, such as furans and other oxygenated hydrocarbons, during the combustion of hydrocarbon fuels. Wemore » used ab initio and probabilistic computational techniques to identify low-barrier reaction mechanisms for the formation of large furans and other oxygenated hydrocarbons. We used vacuum-UV photoionization aerosol mass spectrometry and X-ray photoelectron spectroscopy to confirm these predictions. We show that fura ns are produced in the high- Temperature regions of hydrocarbon flames, where they remarkably survive and become the main functional group of oxygenates that incorporate into incipient soot. In controlled flame studies, we discovered ~100 oxygenated species previously unaccounted for. We found that large alcohols and enols act as precursors to furans, leading to incorporation of oxygen into the carbon skeletons of PAHs. Our results depart dramatically from the crude chemistry of carbonand oxygen-containing molecules previously considered in hydrocarbon formation and oxidation models and spearhead the emerging understanding of the oxidation chemistry that is critical, for example, to control emissions of toxic and carcinogenic combustion by-products, which also greatly affect global warming.« less

Folding of a single domain protein entering the endoplasmic reticulum precedes disulfide formation.

PubMed

Robinson, Philip J; Pringle, Marie Anne; Woolhead, Cheryl A; Bulleid, Neil J

2017-04-28

The relationship between protein synthesis, folding, and disulfide formation within the endoplasmic reticulum (ER) is poorly understood. Previous studies have suggested that pre-existing disulfide links are absolutely required to allow protein folding and, conversely, that protein folding occurs prior to disulfide formation. To address the question of what happens first within the ER, that is, protein folding or disulfide formation, we studied folding events at the early stages of polypeptide chain translocation into the mammalian ER using stalled translation intermediates. Our results demonstrate that polypeptide folding can occur without complete domain translocation. Protein disulfide isomerase (PDI) interacts with these early intermediates, but disulfide formation does not occur unless the entire sequence of the protein domain is translocated. This is the first evidence that folding of the polypeptide chain precedes disulfide formation within a cellular context and highlights key differences between protein folding in the ER and refolding of purified proteins. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The Pliocene Citronelle Formation of the Gulf Coastal Plain

USGS Publications Warehouse

Matson, George Charlton

1916-01-01

In the spring of 1910 the writer, working under the direction of T. Wayland Vaughan, geologist in charge of Coastal Plain investigations, undertook a study of the later Tertiary formations of the Gulf Coastal Plain. According to the plans outlined before the work was begun, the beds that had formerly been grouped under the names Lafayette formation and Grand Gulf formation were to be studied with a view to their possible separation into more satisfactory stratigraphic units that might be correlated with other formations which, on the basis of their fossils, had been assigned to their proper positions in the geologic time scale. The original plan included a study of the post-Vicksburgian Tertiary deposits from western Florida to Mississippi River and correlations with formations previously recognized in Florida, southern Alabama, and Louisiana. This plan was subsequently modified to extend the investigation as far west as Sabine River. The field work was interrupted and the office work was delayed by calls for geologic work in other areas, so that the preparation of the reports could not be begun until the spring of 1914.

Age-Related Impairment on a Forced-Choice Version of the Mnemonic Similarity Task

PubMed Central

Huffman, Derek J.; Stark, Craig E. L.

2018-01-01

Previous studies from our lab have indicated that healthy older adults are impaired in their ability to mnemonically discriminate between previously viewed objects and similar lure objects in the Mnemonic Similarity Task (MST). These studies have used either old/similar/new or old/new test formats. The forced-choice test format (e.g., “Did you see object A or object A’ during the encoding phase?”) relies on different assumptions than the old/new test format (e.g., “Did you see this object during the encoding phase?”); hence, converging evidence from these approaches would bolster the conclusion that healthy aging is accompanied by impaired performance on the MST. Consistent with our hypothesis, healthy older adults exhibited impaired performance on a forced-choice test format that required discriminating between a target and a similar lure. We also tested the hypothesis that age-related impairments on the MST could be modeled within a global matching computational framework. We found that decreasing the probability of successful feature encoding in the models caused changes that were similar to the empirical data in healthy older adults. Collectively, our behavioral results extend to the forced-choice test format the finding that healthy aging is accompanied by an impaired ability to discriminate between targets and similar lures, and our modeling results suggest that a diminished probability of encoding stimulus features is a candidate mechanism for memory changes in healthy aging. We also discuss the ability of global matching models to account for findings in other studies that have used variants on mnemonic similarity tasks. PMID:28004951

Age-related impairment on a forced-choice version of the Mnemonic Similarity Task.

PubMed

Huffman, Derek J; Stark, Craig E L

2017-02-01

Previous studies from our lab have indicated that healthy older adults are impaired in their ability to mnemonically discriminate between previously viewed objects and similar lure objects in the Mnemonic Similarity Task (MST). These studies have used either old/similar/new or old/new test formats. The forced-choice test format (e.g., "Did you see object A or object A' during the encoding phase?") relies on different assumptions than the old/new test format (e.g., "Did you see this object during the encoding phase?"); hence, converging evidence from these approaches would bolster the conclusion that healthy aging is accompanied by impaired performance on the MST. Consistent with our hypothesis, healthy older adults exhibited impaired performance on a forced-choice test format that required discriminating between a target and a similar lure. We also tested the hypothesis that age-related impairments on the MST could be modeled within a global matching computational framework. We found that decreasing the probability of successful feature encoding in the models caused changes that were similar to the empirical data in healthy older adults. Collectively, our behavioral results using the forced-choice format extend the finding that healthy aging is accompanied by an impaired ability to discriminate between targets and similar lures, and our modeling results suggest that a diminished probability of encoding stimulus features is a candidate mechanism for memory changes in healthy aging. We also discuss the ability of global matching models to account for findings in other studies that have used variants on mnemonic similarity tasks. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Microstructure of β-Sitosterol:γ-Oryzanol Edible Organogels.

PubMed

Matheson, Andrew B; Koutsos, Vasileios; Dalkas, Georgios; Euston, Stephen; Clegg, Paul

2017-05-09

Rheology and atomic force microscopy (AFM) were employed to examine the microstructure of β-sitosterol:γ-oryzanol organogels in sunflower oil. Using time-resolved rheology, we followed gel formation, paying specific attention to the fibril aggregation process, which had not been studied in detail previously for this system. Using AFM, we observed gel structures directly and obtained detailed information on the gel structure, far exceeding previous studies. Our analysis suggests that though gels are formed by the self-assembly and aggregation of one-dimensional fibrils, the manner in which these fibrils aggregate into ribbons results in complex structures of higher dimensionality. We emphasize that it is a surprise to find ribbons and not twisted strands. Comparing AFM images of 10% w/w and 20% w/w gelator systems, we observed differences in the degree of branching which are consistent with the rheology. We also observed the individual self-assembled fibrils which make up these gels with much greater clarity than in previous microscopy studies, and the fibril diameters of ∼9.8 nm we measured agree excellently with those obtained from existing small-angle neutron scattering data. These results provide new insight into the structure and formation kinetics of this important organogel system.

Do airborne microbes matter for atmospheric chemistry and cloud formation?

PubMed

Konstantinidis, Konstantinos T

2014-06-01

The role of airborne microbial cells in the chemistry of the atmosphere and cloud formation remains essentially speculative. Recent studies have indicated that microbes might be more important than previously anticipated for atmospheric processes. However, more work and direct communication between microbiologists and atmospheric scientists and modellers are necessary to better understand and model bioaerosol-cloud-precipitation-climate interactions. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Competition for water vapour results in suppression of ice formation in mixed-phase clouds

NASA Astrophysics Data System (ADS)

Simpson, Emma L.; Connolly, Paul J.; McFiggans, Gordon

2018-05-01

The formation of ice in clouds can initiate precipitation and influence a cloud's reflectivity and lifetime, affecting climate to a highly uncertain degree. Nucleation of ice at elevated temperatures requires an ice nucleating particle (INP), which results in so-called heterogeneous freezing. Previously reported measurements for the ability of a particle to nucleate ice have been made in the absence of other aerosol which will act as cloud condensation nuclei (CCN) and are ubiquitous in the atmosphere. Here we show that CCN can outcompete INPs for available water vapour thus suppressing ice formation, which has the potential to significantly affect the Earth's radiation budget. The magnitude of this suppression is shown to be dependent on the mass of condensed water required for freezing. Here we show that ice formation in a state-of-the-art cloud parcel model is strongly dependent on the criteria for heterogeneous freezing selected from those previously hypothesised. We have developed an alternative criteria which agrees well with observations from cloud chamber experiments. This study demonstrates the dominant role that competition for water vapour can play in ice formation, highlighting both a need for clarity in the requirements for heterogeneous freezing and for measurements under atmospherically appropriate conditions.

Direct antioxidant properties of methotrexate: Inhibition of malondialdehyde-acetaldehyde-protein adduct formation and superoxide scavenging.

PubMed

Zimmerman, Matthew C; Clemens, Dahn L; Duryee, Michael J; Sarmiento, Cleofes; Chiou, Andrew; Hunter, Carlos D; Tian, Jun; Klassen, Lynell W; O'Dell, James R; Thiele, Geoffrey M; Mikuls, Ted R; Anderson, Daniel R

2017-10-01

Methotrexate (MTX) is an immunosuppressant commonly used for the treatment of autoimmune diseases. Recent observations have shown that patients treated with MTX also exhibit a reduced risk for the development of cardiovascular disease (CVD). Although MTX reduces systemic inflammation and tissue damage, the mechanisms by which MTX exerts these beneficial effects are not entirely known. We have previously demonstrated that protein adducts formed by the interaction of malondialdehyde (MDA) and acetaldehyde (AA), known as MAA-protein adducts, are present in diseased tissues of individuals with rheumatoid arthritis (RA) or CVD. In previously reported studies, MAA-adducts were shown to be highly immunogenic, supporting the concept that MAA-adducts not only serve as markers of oxidative stress but may have a direct role in the pathogenesis of inflammatory diseases. Because MAA-adducts are commonly detected in diseased tissues and are proposed to mitigate disease progression in both RA and CVD, we tested the hypothesis that MTX inhibits the generation of MAA-protein adducts by scavenging reactive oxygen species. Using a cell free system, we found that MTX reduces MAA-adduct formation by approximately 6-fold, and scavenges free radicals produced during MAA-adduct formation. Further investigation revealed that MTX directly scavenges superoxide, but not hydrogen peroxide. Additionally, using the Nrf2/ARE luciferase reporter cell line, which responds to intracellular redox changes, we observed that MTX inhibits the activation of Nrf2 in cells treated with MDA and AA. These studies define previously unrecognized mechanisms by which MTX can reduce inflammation and subsequent tissue damage, namely, scavenging free radicals, reducing oxidative stress, and inhibiting MAA-adduct formation. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Otoconia as test masses in biological accelerometers: what can we learn about their formation from evolutionary studies and from work in microgravity?

PubMed

Ross, M D; Donovan, K M

1986-01-01

This paper reviews previous findings and introduces new material about otolith end organs that help us to understand their functioning and development. In particular, we consider the end organs as biological accelerometers. The otoconia are dealt with as test masses whose substructure and evolutionary trend toward calcite may prove significant in understanding formation requirements. Space-flight helps illuminate the influence of gravity, while right-left asymmetry is suggested by study of certain rat strains.

Sonic horizon formation for oscillating Bose-Einstein condensates in isotropic harmonic potential

PubMed Central

Wang, Ying; Zhou, Yu; Zhou, Shuyu

2016-01-01

We study the sonic horizon phenomena of the oscillating Bose-Einstein condensates in isotropic harmonic potential. Based on the Gross-Pitaevskii equation model and variational method, we derive the original analytical formula for the criteria and lifetime of the formation of the sonic horizon, demonstrating pictorially the interaction parameter dependence for the occur- rence of the sonic horizon and damping effect of the system distribution width. Our analytical results corroborate quantitatively the particular features of the sonic horizon reported in previous numerical study. PMID:27922129

Photoaggregation of crystallins (main proteins of eye lens) under the effect of XeCl laser radiation

NASA Astrophysics Data System (ADS)

Soustov, Lev V.; Chelnokov, Evgeny V.; Bityurin, Nikita M.; Kiselev, A. L.; Nemov, V. V.; Sergeev, Yu. V.; Ostrovsky, Michail A.

2004-07-01

UV light is one of primary factors associated with cataract formation in the eye lens. α-, β-, γ-Crystallins maintain lens transparency, and damage to these proteins plays a major role in cataract formation. The effect of XeCl laser radiation (308 nm) on βL-crystallin solution is studied. The strong dependence of protein aggregation kinetics on both laser fluence (w) and repetition rate (F) is investigated. The kinetics features are similar to those of carbonic anhydrase photoaggregation studied previously.

Making Online Products More Tangible: The Effect of Product Presentation Formats on Product Evaluations.

PubMed

Verhagen, Tibert; Vonkeman, Charlotte; van Dolen, Willemijn

2016-07-01

Although several studies have looked at the effects of online product presentations on consumer decision making, no study thus far has considered a potential key factor in online product evaluations: tangibility. The present study aims at filling this gap by developing and testing a model that relates different online product presentation formats to the three-dimensional concept of product tangibility. We test how the three tangibility dimensions influence perceived diagnosticity and, eventually, online purchase intentions. A between-subjects lab experiment (n = 366) was used to test the hypothesized effects of three common online product presentation formats (pictures vs. 360 spin rotation vs. virtual mirror). The results showed that out of these formats, virtual mirrors were superior in providing a sense of product tangibility, followed by the 360-spin rotation format and static pictures. Furthermore, in terms of predictive validity, two of the three tangibility dimensions significantly increased perceived diagnosticity, which, in turn, positively and strongly affected purchase intentions. Overall, our results add to previous works studying the relationships between online product presentation formats and consumer decision making. Also, they hold value for online practitioners by highlighting the potential benefits of applying technologically advanced product presentation formats such as the virtual mirror.

Multiple Behavior Descriptions Affect the Acquisitions of STI and STT.

PubMed

McCarthy, Randy J; Wells, Brett M; Skowronski, John J; Carlston, Donal E

2017-01-01

Four studies pursued the idea that spontaneous trait inferences (STIs) involve the formation of both inferential knowledge and associative knowledge while spontaneous trait transferences (STTs) involve only the formation of associative knowledge. These studies varied the type and amount of behavioral information from which perceivers could extract trait information. Experiments 1a and 1b used a modified savings-in-relearning paradigm and demonstrated that repeated presentations of an individual and a behavior description increased the strength of association between the target and implied trait, and this effect did not depend on whether the repeated presentations involved redundant information or new information. In comparison, Experiments 2a and 2b used a trait ratings dependent variable and demonstrated that the effects of repetition were stronger for STI, but not STT, when the added information differed from information that was previously encountered, but not when it was redundant with the previously encountered information.

Misconceptions of Astronomical Distances

ERIC Educational Resources Information Center

Miller, Brian W.; Brewer, William F.

2010-01-01

Previous empirical studies using multiple-choice procedures have suggested that there are misconceptions about the scale of astronomical distances. The present study provides a quantitative estimate of the nature of this misconception among US university students by asking them, in an open-ended response format, to make estimates of the distances…

Effects of Low-Dose Amoxicillin on Staphylococcus aureus USA300 Biofilms.

PubMed

Mlynek, Kevin D; Callahan, Mary T; Shimkevitch, Anton V; Farmer, Jackson T; Endres, Jennifer L; Marchand, Mélodie; Bayles, Kenneth W; Horswill, Alexander R; Kaplan, Jeffrey B

2016-05-01

Previous studies showed that sub-MIC levels of β-lactam antibiotics stimulate biofilm formation in most methicillin-resistant Staphylococcus aureus (MRSA) strains. Here, we investigated this process by measuring the effects of sub-MIC amoxicillin on biofilm formation by the epidemic community-associated MRSA strain USA300. We found that sub-MIC amoxicillin increased the ability of USA300 cells to attach to surfaces and form biofilms under both static and flow conditions. We also found that USA300 biofilms cultured in sub-MIC amoxicillin were thicker, contained more pillar and channel structures, and were less porous than biofilms cultured without antibiotic. Biofilm formation in sub-MIC amoxicillin correlated with the production of extracellular DNA (eDNA). However, eDNA released by amoxicillin-induced cell lysis alone was evidently not sufficient to stimulate biofilm. Sub-MIC levels of two other cell wall-active agents with different mechanisms of action-d-cycloserine and fosfomycin-also stimulated eDNA-dependent biofilm, suggesting that biofilm formation may be a mechanistic adaptation to cell wall stress. Screening a USA300 mariner transposon library for mutants deficient in biofilm formation in sub-MIC amoxicillin identified numerous known mediators of S. aureus β-lactam resistance and biofilm formation, as well as novel genes not previously associated with these phenotypes. Our results link cell wall stress and biofilm formation in MRSA and suggest that eDNA-dependent biofilm formation by strain USA300 in low-dose amoxicillin is an inducible phenotype that can be used to identify novel genes impacting MRSA β-lactam resistance and biofilm formation. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

SMU.940 regulates dextran-dependent aggregation and biofilm formation in Streptococcus mutans.

PubMed

Senpuku, Hidenobu; Yonezawa, Hideo; Yoneda, Saori; Suzuki, Itaru; Nagasawa, Ryo; Narisawa, Naoki

2018-02-01

The oral bacterium Streptococcus mutans is the principal agent in the development of dental caries. Biofilm formation by S. mutans requires bacterial attachment, aggregation, and glucan formation on the tooth surface under sucrose supplementation conditions. Our previous microarray analysis of clinical strains identified 74 genes in S. mutans that were related to biofilm morphology; however, the roles of almost all of these genes in biofilm formation are poorly understood. We investigated the effects of 21 genes randomly selected from our previous study regarding S. mutans biofilm formation, regulation by the complement pathway, and responses to competence-stimulating peptide. Eight competence-stimulating peptide-dependent genes were identified, and their roles in biofilm formation and aggregation were examined by mutational analyses of the S. mutansUA159 strain. Of these eight genes, the inactivation of the putative hemolysin III family SMU.940 gene of S. mutansUA159 promoted rapid dextran-dependent aggregation and biofilm formation in tryptic soy broth without dextrose (TSB) with 0.25% glucose and slightly reduced biofilm formation in TSB with 0.25% sucrose. The SMU.940 mutant showed higher expression of GbpC and gbpC gene than wild-type. GbpC is known to be involved in the dextran-dependent aggregation of S. mutans. An SMU.940-gbpC double mutant strain was constructed in the SMU.940 mutant background. The gbpC mutation completely abolished the dextran-dependent aggregation of the SMU.940 mutant. In addition, the aggregation of the mutant was abrogated by dextranase. These findings suggest that SMU.940 controls GbpC expression, and contributes to the regulation of dextran-dependent aggregation and biofilm formation. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Separate Ways: The Mass-Metallicity Relation Does Not Strongly Correlate with Star Formation Rate in SDSS-IV MaNGA Galaxies

NASA Astrophysics Data System (ADS)

Barrera-Ballesteros, J. K.; Sánchez, S. F.; Heckman, T.; Blanc, G. A.; The MaNGA Team

2017-07-01

We present the integrated stellar mass-metallicity relation (MZR) for more than 1700 galaxies included in the integral field area SDSS-IV MaNGA survey. The spatially resolved data allow us to determine the metallicity at the same physical scale (effective radius, R eff) using a heterogeneous set of 10 abundance calibrators. In addition to scale factors, the shape of the MZR is similar for all calibrators, consistent with those reported previously using single-fiber and integral field spectroscopy. We compare the residuals of this relation against the star formation rate (SFR) and specific SFR (sSFR). We do not find a strong secondary relation of the MZR with either SFR or sSFR for any of the calibrators, in contrast with previous single-fiber spectroscopic studies. Our results agree with a scenario in which metal enrichment happens at local scales, with global outflows playing a secondary role in shaping the chemistry of galaxies and cold-gas inflows regulating the stellar formation.

The Brain/MINDS 3D digital marmoset brain atlas

PubMed Central

Woodward, Alexander; Hashikawa, Tsutomu; Maeda, Masahide; Kaneko, Takaaki; Hikishima, Keigo; Iriki, Atsushi; Okano, Hideyuki; Yamaguchi, Yoko

2018-01-01

We present a new 3D digital brain atlas of the non-human primate, common marmoset monkey (Callithrix jacchus), with MRI and coregistered Nissl histology data. To the best of our knowledge this is the first comprehensive digital 3D brain atlas of the common marmoset having normalized multi-modal data, cortical and sub-cortical segmentation, and in a common file format (NIfTI). The atlas can be registered to new data, is useful for connectomics, functional studies, simulation and as a reference. The atlas was based on previously published work but we provide several critical improvements to make this release valuable for researchers. Nissl histology images were processed to remove illumination and shape artifacts and then normalized to the MRI data. Brain region segmentation is provided for both hemispheres. The data is in the NIfTI format making it easy to integrate into neuroscience pipelines, whereas the previous atlas was in an inaccessible file format. We also provide cortical, mid-cortical and white matter boundary segmentations useful for visualization and analysis. PMID:29437168

Blister formation at subcritical doses in tungsten irradiated by MeV protons

NASA Astrophysics Data System (ADS)

Gavish Segev, I.; Yahel, E.; Silverman, I.; Makov, G.

2017-12-01

The material response of tungsten to irradiation by MeV protons has been studied experimentally, in particular with respect to bubble and blister formation. Tungsten samples were irradiated by 2.2 MeV protons at the Soreq Applied Research Accelerator Facility (SARAF) to doses of the order of 1017 protons/cm2 which are below the reported critical threshold for blister formation derived from keV range irradiation studies. Large, well-developed blisters are observed indicating that for MeV range protons the critical threshold is at least an order of magnitude lower than the lowest value reported previously. The effects of fluence, flux, and corresponding temperature on the distribution and characteristics of the obtained blisters were studied. FIB cross sections of several blisters exposed their depth and structure.

Predicting Reactive Intermediate Quantum Yields from Dissolved Organic Matter Photolysis Using Optical Properties and Antioxidant Capacity.

PubMed

Mckay, Garrett; Huang, Wenxi; Romera-Castillo, Cristina; Crouch, Jenna E; Rosario-Ortiz, Fernando L; Jaffé, Rudolf

2017-05-16

The antioxidant capacity and formation of photochemically produced reactive intermediates (RI) was studied for water samples collected from the Florida Everglades with different spatial (marsh versus estuarine) and temporal (wet versus dry season) characteristics. Measured RI included triplet excited states of dissolved organic matter ( 3 DOM*), singlet oxygen ( 1 O 2 ), and the hydroxyl radical ( • OH). Single and multiple linear regression modeling were performed using a broad range of extrinsic (to predict RI formation rates, R RI ) and intrinsic (to predict RI quantum yields, Φ RI ) parameters. Multiple linear regression models consistently led to better predictions of R RI and Φ RI for our data set but poor prediction of Φ RI for a previously published data set,1 probably because the predictors are intercorrelated (Pearson's r > 0.5). Single linear regression models were built with data compiled from previously published studies (n ≈ 120) in which E2:E3, S, and Φ RI values were measured, which revealed a high degree of similarity between RI-optical property relationships across DOM samples of diverse sources. This study reveals that • OH formation is, in general, decoupled from 3 DOM* and 1 O 2 formation, providing supporting evidence that 3 DOM* is not a • OH precursor. Finally, Φ RI for 1 O 2 and 3 DOM* correlated negatively with antioxidant activity (a surrogate for electron donating capacity) for the collected samples, which is consistent with intramolecular oxidation of DOM moieties by 3 DOM*.

Positron scattering from molecular hydrogen

NASA Astrophysics Data System (ADS)

Machacek, J. R.; Anderson, E. K.; Makochekanwa, C.; Buckman, S. J.; Sullivan, J. P.

2013-10-01

We present results for total and partial cross sections for positron scattering from H2. The total scattering and positronium formation cross sections are reported between 0.5 and 200 eV. Total quasielastic and inelastic scattering cross sections are reported for energies between the positronium formation threshold and 50 eV, with quasielastic differential scattering cross sections reported at 1, 3, 5, 7, and 10 eV. Our results are compared with previous work, both experimental and theoretical, with particular attention paid to the region below the positronium formation threshold, where there are apparent discrepancies in previous work. A discussion of possible reasons for discrepancies between this and previous work is presented, including a focus on known systematic effects in the experimental results.

Representational Task Formats and Problem Solving Strategies in Kinematics and Work

ERIC Educational Resources Information Center

Ibrahim, Bashirah; Rebello, N. Sanjay

2012-01-01

Previous studies have reported that students employed different problem solving approaches when presented with the same task structured with different representations. In this study, we explored and compared students' strategies as they attempted tasks from two topical areas, kinematics and work. Our participants were 19 engineering students…

BENCH-SCALE STUDIES ON THE SIMULTANEOUS FORMATION OF PCBS AND PCDDS/FS FROM COMBUSTION SYSTEMS

EPA Science Inventory

The paper reports on a bench-scale experimental study to characterize a newly built reactor system that was built to: produce levels and distributions of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F) production similar to those achieved by previous re...

Characterizing High School Chemistry Teachers' Use of Assessment Data via Latent Class Analysis

ERIC Educational Resources Information Center

Harshman, Jordan; Yezierski, Ellen

2016-01-01

In this study, which builds on a previous qualitative study and literature review, high school chemistry teachers' characteristics regarding the design of chemistry formative assessments and interpretation of results for instructional improvement are identified. The Adaptive Chemistry Assessment Survey for Teachers (ACAST) was designed to elicit…

Structure formation in Ag-X (X = Au, Cu) alloys synthesized far-from-equilibrium

NASA Astrophysics Data System (ADS)

Elofsson, V.; Almyras, G. A.; Lü, B.; Garbrecht, M.; Boyd, R. D.; Sarakinos, K.

2018-04-01

We employ sub-monolayer, pulsed Ag and Au vapor fluxes, along with deterministic growth simulations, and nanoscale probes to study structure formation in miscible Ag-Au films synthesized under far-from-equilibrium conditions. Our results show that nanoscale atomic arrangement is primarily determined by roughness build up at the film growth front, whereby larger roughness leads to increased intermixing between Ag and Au. These findings suggest a different structure formation pathway as compared to the immiscible Ag-Cu system for which the present study, in combination with previously published data, reveals that no significant roughness is developed, and the local atomic structure is predominantly determined by the tendency of Ag and Cu to phase-separate.

Improving Student Content Knowledge in Inclusive Social Studies Classrooms Using Technology-Based Cognitive Organizers: A Systematic Replication

ERIC Educational Resources Information Center

Boon, Richard T.; Burke, Mack D.; Fore, Cecil, III; Hagan-Burke, Shanna

2006-01-01

The purpose of this study was to conduct a systematic replication of a previous study (Boon, Burke, Fore, & Spencer, 2006) on the effects of computer-generated cognitive organizers using Inspiration 6 software versus a traditional textbook instruction format on students' ability to comprehend social studies content information in high school…

Fabric-based alkaline direct formate microfluidic fuel cells.

PubMed

Domalaon, Kryls; Tang, Catherine; Mendez, Alex; Bernal, Franky; Purohit, Krutarth; Pham, Linda; Haan, John; Gomez, Frank A

2017-04-01

Fabric-based microfluidic fuel cells (MFCs) serve as a novel, cost-efficient alternative to traditional FCs and batteries, since fluids naturally travel across fabric via capillary action, eliminating the need for an external pump and lowering production and operation costs. Building on previous research with Y-shaped paper-based MFCs, fabric-based MFCs mitigate fragility and durability issues caused by long periods of fuel immersion. In this study, we describe a microfluidic fabric-based direct formate fuel cell, with 5 M potassium formate and 30% hydrogen peroxide as the anode fuel and cathode oxidant, respectively. Using a two-strip, stacked design, the optimized parameters include the type of encasement, the barrier, and the fabric type. Surface contact of the fabric and laminate sheet expedited flow and respective chemical reactions. The maximum current (22.83 mA/cm 2 ) and power (4.40 mW/cm 2 ) densities achieved with a 65% cotton/35% polyester blend material are a respective 8.7% and 32% higher than previous studies with Y-shaped paper-based MFCs. In series configuration, the MFCs generate sufficient energy to power a handheld calculator, a thermometer, and a spectrum of light-emitting diodes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On the formation and early evolution of soot in turbulent nonpremixed flames

NASA Astrophysics Data System (ADS)

Bisetti, F.; Blanquart, G.; Mueller, M. E.; Pitsch, H.

2010-11-01

A direct numerical simulation of soot formation in a turbulent nonpremixed flame has been performed to investigate unsteady hydrodynamic strain effects on soot growth processes and transport immediately following nucleation. For the first time in a DNS, polycyclic aromatic hydrocarbon (PAH) species are included in the chemical kinetics mechanism to describe soot inception. A novel statistical representation of soot aggregates based on the Hybrid Method of Moments (HMOM) is employed. In agreement with previous experimental studies in laminar flames, Damköhler number effects are significant, and soot nucleation and growth are locally inhibited by high scalar dissipation rate. Upon formation on the rich side of the flame, soot is displaced relative to curved mixture fraction iso-surfaces due to differential diffusion effects. Soot traveling towards the flame is oxidized, and aggregates displaced away from the flame grow by condensation of PAH species on the surface of soot aggregates. In contrast to previous DNS studies employing simplified models, we find that soot-flame interaction plays a limited role in soot growth. Nucleation and condensation processes occurring in the fuel stream are responsible for the greatest generation of soot mass.

A detailed kinetic modeling study of aromatics formation in laminar premixed acetylene and ethylene flames

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

Wang, H.; Frenklach, M.

1997-07-01

A computational study was performed for the formation and growth of polycyclic aromatic hydrocarbons (PAHs) in laminar premixed acetylene and ethylene flames. A new detailed reaction mechanism describing fuel pyrolysis and oxidation, benzene formation, and PAH mass growth and oxidation is presented and critically tested. It is shown that the reaction model predicts reasonably well the concentration profiles of major and intermediate species and aromatic molecules in a number of acetylene and ethylene flames reported in the literature. It is demonstrated that reactions of n-C{sub 4}H{sub x} + C{sub 2}H{sub 2} leading to the formation of one-ring aromatics are asmore » important as the propargyl recombination, and hence must be included in kinetic modeling of PAH formation in hydrocarbon flames. It is further demonstrated that the mass growth of PAHs can be accounted for by the previously proposed H-abstraction-C{sub 2}H{sub 2}-addiction mechanism.« less

Experimental evidence for glycolaldehyde and ethylene glycol formation by surface hydrogenation of CO molecules under dense molecular cloud conditions

NASA Astrophysics Data System (ADS)

Fedoseev, G.; Cuppen, H. M.; Ioppolo, S.; Lamberts, T.; Linnartz, H.

2015-04-01

This study focuses on the formation of two molecules of astrobiological importance - glycolaldehyde (HC(O)CH2OH) and ethylene glycol (H2C(OH)CH2OH) - by surface hydrogenation of CO molecules. Our experiments aim at simulating the CO freeze-out stage in interstellar dark cloud regions, well before thermal and energetic processing become dominant. It is shown that along with the formation of H2CO and CH3OH - two well-established products of CO hydrogenation - also molecules with more than one carbon atom form. The key step in this process is believed to be the recombination of two HCO radicals followed by the formation of a C-C bond. The experimentally established reaction pathways are implemented into a continuous-time random-walk Monte Carlo model, previously used to model the formation of CH3OH on astrochemical time-scales, to study their impact on the solid-state abundances in dense interstellar clouds of glycolaldehyde and ethylene glycol.

Parametric Study of Amorphous High-Entropy Alloys formation from two New Perspectives: Atomic Radius Modification and Crystalline Structure of Alloying Elements

NASA Astrophysics Data System (ADS)

Hu, Q.; Guo, S.; Wang, J. M.; Yan, Y. H.; Chen, S. S.; Lu, D. P.; Liu, K. M.; Zou, J. Z.; Zeng, X. R.

2017-01-01

Chemical and topological parameters have been widely used for predicting the phase selection in high-entropy alloys (HEAs). Nevertheless, previous studies could be faulted due to the small number of available data points, the negligence of kinetic effects, and the insensitivity to small compositional changes. Here in this work, 92 TiZrHfM, TiZrHfMM, TiZrHfMMM (M = Fe, Cr, V, Nb, Al, Ag, Cu, Ni) HEAs were prepared by melt spinning, to build a reliable and sufficiently large material database to inspect the robustness of previously established parameters. Modification of atomic radii by considering the change of local electronic environment in alloys, was critically found out to be superior in distinguishing the formation of amorphous and crystalline alloys, when compared to using atomic radii of pure elements in topological parameters. Moreover, crystal structures of alloying element were found to play an important role in the amorphous phase formation, which was then attributed to how alloying hexagonal-close-packed elements and face-centered-cubic or body-centered-cubic elements can affect the mixing enthalpy. Findings from this work not only provide parametric studies for HEAs with new and important perspectives, but also reveal possibly a hidden connection among some important concepts in various fields.

Characterizing Protoplanetary Disks in a Young Binary in Orion

NASA Astrophysics Data System (ADS)

Powell, Jonas; Hughes, A. Meredith; Mann, Rita; Flaherty, Kevin; Di Francesco, James; Williams, Jonathan

2018-01-01

Planetary systems form in circumstellar disks of gas and dust surrounding young stars. One open question in the study of planet formation involves understanding how different environments affect the properties of the disks and planets they generate. Understanding the properties of disks in high-mass star forming regions (SFRs) is critical since most stars - probably including our Sun - form in those regions. By comparing the disks in high-mass SFRs to those in better-studied low-mass SFRs we can learn about the role environment plays in planet formation. Here we present 0.5" resolution observations of the young two-disk binary system V2434 Ori in the Orion Nebula from the Atacama Large Millimeter/submillimeter Array (ALMA) in molecular line tracers of CO(3-2), HCN(4-3), HCO+(4-3) and CS(7-6). We model each disk’s mass, radius, temperature structure, and molecular abundances, by creating synthetic images using an LTE ray-tracing code and comparing simulated observations with the ALMA data in the visibility domain. We then compare our results to a previous study of molecular line emission from a single Orion proplyd, modeled using similar methods, and to previously characterized disks in low-mass SFRs to investigate the role of environment in disk chemistry and planetary system formation.

The interaction of assessment format and sex in assessing the knowledge structure coherence of middle school students' understanding of the concept of force

NASA Astrophysics Data System (ADS)

Schleigh, Sharon

This study focuses on the impact of assessment format on the identification of students' ideas surrounding the concept of force and the consistency with which students apply those ideas across contexts. It is in response to the debate in conceptual change literature regarding students' knowledge structure coherence. Empirical studies in this field typically rely on an interview assessment format. The current study examined the potential of a constructed response assessment format as another possible instrument for data collection involving larger sample populations. The current study specifically compared how the two assessment formats (constructed response and interview assessment) assessed 45 students in the ninth grade in a single school in Arizona. The analysis explored possible biases and interactions by sex, order of assessment, and preference for assessment format because the literature suggests that these factors may potentially affect the performance and coding of assessments. Although small differences between the two assessments were found, the differences were not statistically significant overall or for any subgroup. More specifically, there were no apparent significant biases in the two formats with regard to one another and student sex. However it was found that girls are more likely to express multiple-best match meanings than boys in both assessments. This may be an influence in the diversity found in previous studies concerning students' knowledge structures. These findings suggest that the constructed response format could be administered on a larger scale to assist in the identification of factors contributing to the differences in findings across prior studies in this field. Additionally, these results suggest the potential of this constructed response format for helping teachers conduct formative assessments to guide instructional decisions.

Quantum chemical studies of a model for peptide bond formation. 3. Role of magnesium cation in formation of amide and water from ammonia and glycine

NASA Technical Reports Server (NTRS)

Oie, T.; Loew, G. H.; Burt, S. K.; MacElroy, R. D.

1984-01-01

The SN2 reaction between glycine and ammonia molecules with magnesium cation Mg2+ as a catalyst has been studied as a model reaction for Mg(2+)-catalyzed peptide bond formation using the ab initio Hartree-Fock molecular orbital method. As in previous studies of the uncatalyzed and amine-catalyzed reactions between glycine and ammonia, two reaction mechanisms have been examined, i.e., a two-step and a concerted reaction. The stationary points of each reaction including intermediate and transition states have been identified and free energies calculated for all geometry-optimized reaction species to determine the thermodynamics and kinetics of each reaction. Substantial decreases in free energies of activation were found for both reaction mechanisms in the Mg(2+)-catalyzed amide bond formation compared with those in the uncatalyzed and amine-catalyzed amide bond formation. The catalytic effect of the Mg2+ cation is to stabilize both the transition states and intermediate, and it is attributed to the neutralization of the developing negative charge on the electrophile and formation of a conformationally flexible nonplanar five-membered chelate ring structure.

Simulating Shock Triggered Star Formation with AstroBEAR2.0

NASA Astrophysics Data System (ADS)

Li, Shule; Frank, Adam; Blackman, Eric

2013-07-01

Star formation can be triggered by the compression from shocks running over stable clouds. Triggered star formation is a favored explanation for the traces of SLRI's in our solar system. Previous research has shown that when parameters such as shock speed are within a certain range, the gravitational collapse of otherwise stable, dense cloud cores is possible. However, these studies usually focus on the precursors of star formation, and the conditions for the triggering. We use AstroBEAR2.0 code to simulate the collapse and subsequent evolution of a stable Bonnor-Ebert cloud by an incoming shock. Through our simulations, we show that interesting physics happens when the newly formed star interacts with the cloud residue and the post-shock flow. We identify these interactions as controlled by the initial conditions of the triggering and study the flow pattern as well as the evolution of important physics quantities such as accretion rate and angular momentum.

How the bimodal format of presentation affects working memory: an overview.

PubMed

Mastroberardino, Serena; Santangelo, Valerio; Botta, Fabiano; Marucci, Francesco S; Olivetti Belardinelli, Marta

2008-03-01

The best format in which information that has to be recalled is presented has been investigated in several studies, which focused on the impact of bimodal stimulation on working memory performance. An enhancement of participant's performance in terms of correct recall has been repeatedly found, when bimodal formats of presentation (i.e., audiovisual) were compared to unimodal formats (i.e, either visual or auditory), in providing implications for multimedial learning. Several theoretical frameworks have been suggested in order to account for the bimodal advantage, ranging from those emphasizing early stages of processing (such as automatic alerting effects or multisensory integration processes) to those centred on late stages of processing (as postulated by the dual coding theory). The aim of this paper is to review previous contributions to this topic, providing a comprehensive theoretical framework, which is updated by the latest empirical studies.

Artifact formation during smoke trapping: An improved method for determination of N-nitrosamines in cigarette smoke

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

Caldwell, W.S.; Conner, J.M.

Studies in our laboratory revealed artifactual formation of N-nitrosamines during trapping of mainstream and sidestream tobacco smoke by the method of Hoffmann and coworkers. Both volatile and tobacco-specific N-nitrosamines were produced. This artifact formation took place on the Cambridge filter, which is part of the collection train used in the previously published procedure. When the filter was treated with ascorbic acid before smoke collection, artifact formation was inhibited. The improved method resulting from these studies was applied to a comparative analysis of N-nitrosamines in smoke from cigarettes that heat, but do not burn, tobacco (the test cigarette) and several referencemore » cigarettes. Concentrations of volatile and tobacco-specific N-nitrosamines in both mainstream and sidestream smoke from the test cigarette were substantially lower than in the reference cigarettes.« less

Total Electron-Impact Ionization Cross-Sections of CFx and NFx (x = 1 - 3)

NASA Technical Reports Server (NTRS)

Huo, Winifred M.; Tarnovsky, Vladimir; Becker, Kurt H.; Kwak, Dochan (Technical Monitor)

2001-01-01

The discrepancy between experimental and theoretical total electron-impact ionization cross sections for a group of fluorides, CFx, and NFx, (x = 1 - 3), is attributed to the inadequacies in previous theoretical models. Cross-sections calculated using a recently developed siBED (simulation Binary-Encounter-Dipole) model that takes into account the shielding of the long-range dipole potential between the scattering electron and target are in agreement with experimentation. The present study also carefully reanalyzed the previously reported experimental data to account for the possibility of incomplete collection of fragment ions and the presence of ion-pair formation channels. For NF3, our experimental and theoretical cross-sections compare well with the total ionization cross-sections recently reported by Haaland et al. in the region below dication formation.

BMP-2 and titanium particles synergistically activate osteoclast formation

PubMed Central

Sun, S.X.; Guo, H.H.; Zhang, J.; Yu, B.; Sun, K.N.; Jin, Q.H.

2014-01-01

A previous study showed that BMP-2 (bone morphogenetic protein-2) and wear debris can separately support osteoclast formation induced by the receptor activator of NF-κB ligand (RANKL). However, the effect of BMP-2 on wear debris-induced osteoclast formation is unclear. In this study, we show that neither titanium particles nor BMP-2 can induce osteoclast formation in RAW 264.7 mouse leukemic monocyte macrophage cells but that BMP-2 synergizes with titanium particles to enhance osteoclast formation in the presence of RANKL, and that at a low concentration, BMP-2 has an optimal effect to stimulate the size and number of multinuclear osteoclasts, expression of osteoclast genes, and resorption area. Our data also clarify that the effects caused by the increase in BMP-2 on phosphorylated SMAD levels such as c-Fos expression increased throughout the early stages of osteoclastogenesis. BMP-2 and titanium particles stimulate the expression of p-JNK, p-P38, p-IkB, and P50 compared with the titanium group. These data suggested that BMP-2 may be a crucial factor in titanium particle-mediated osteoclast formation. PMID:24820069

The comER Gene Plays an Important Role in Biofilm Formation and Sporulation in both Bacillus subtilis and Bacillus cereus.

PubMed

Yan, Fang; Yu, Yiyang; Wang, Luyao; Luo, Yuming; Guo, Jian-Hua; Chai, Yunrong

2016-01-01

Bacteria adopt alternative cell fates during development. In Bacillus subtilis, the transition from planktonic growth to biofilm formation and sporulation is controlled by a complex regulatory circuit, in which the most important event is activation of Spo0A, a transcription factor and a master regulator for genes involved in both biofilm formation and sporulation. In B. cereus, the regulatory pathway controlling biofilm formation and cell differentiation is much less clear. In this study, we show that a novel gene, comER, plays a significant role in biofilm formation as well as sporulation in both B. subtilis and B. cereus. Mutations in the comER gene result in defects in biofilm formation and a delay in spore formation in the two Bacillus species. Our evidence supports the idea that comER may be part of the regulatory circuit that controls Spo0A activation. comER likely acts upstream of sda, a gene encoding a small checkpoint protein for both sporulation and biofilm formation, by blocking the phosphor-relay and thereby Spo0A activation. In summary, our studies outlined a conserved, positive role for comER, a gene whose function was previously uncharacterized, in the regulation of biofilm formation and sporulation in the two Bacillus species.

The comER Gene Plays an Important Role in Biofilm Formation and Sporulation in both Bacillus subtilis and Bacillus cereus

PubMed Central

Yan, Fang; Yu, Yiyang; Wang, Luyao; Luo, Yuming; Guo, Jian-hua; Chai, Yunrong

2016-01-01

Bacteria adopt alternative cell fates during development. In Bacillus subtilis, the transition from planktonic growth to biofilm formation and sporulation is controlled by a complex regulatory circuit, in which the most important event is activation of Spo0A, a transcription factor and a master regulator for genes involved in both biofilm formation and sporulation. In B. cereus, the regulatory pathway controlling biofilm formation and cell differentiation is much less clear. In this study, we show that a novel gene, comER, plays a significant role in biofilm formation as well as sporulation in both B. subtilis and B. cereus. Mutations in the comER gene result in defects in biofilm formation and a delay in spore formation in the two Bacillus species. Our evidence supports the idea that comER may be part of the regulatory circuit that controls Spo0A activation. comER likely acts upstream of sda, a gene encoding a small checkpoint protein for both sporulation and biofilm formation, by blocking the phosphor-relay and thereby Spo0A activation. In summary, our studies outlined a conserved, positive role for comER, a gene whose function was previously uncharacterized, in the regulation of biofilm formation and sporulation in the two Bacillus species. PMID:27446060

Adducin in tumorigenesis and metastasis.

PubMed

Luo, Cong; Shen, Jiayu

2017-07-18

Adducin is a membrane-skeletal protein localized at spectrin-actin junctions, involving in the formation of the network of cytoskeleton, cellular signal transduction, ionic transportation, cell motility and cell proliferation. While previous researches focused mainly on the relationship between adducin and hypertension, there are few studies focusing on the role of adducin in tumor. Previous studies showed that adducin played a role in the evolution and progression of neoplasm. This review makes a brief summary on the structure, function and mechanism of adducin and how adducin functions in tumorigenesis and metastasis.

Percutaneous radiofrequency ablation of hepatic tumours: factors affecting technical failure of artificial ascites formation using an angiosheath.

PubMed

Kang, T W; Lee, M W; Hye, M J; Song, K D; Lim, S; Rhim, H; Lim, H K; Cha, D I

2014-12-01

To evaluate the technical feasibility of artificial ascites formation using an angiosheath before percutaneous radiofrequency ablation (RFA) for hepatic tumours and to determine predictive factors affecting the technical failure of artificial ascites formation. This retrospective study was approved by the institutional review board. One hundred and thirteen patients underwent percutaneous RFA of hepatic tumours after trying to make artificial ascites using an angiosheath to avoid collateral thermal damage. The technical success rate of making artificial ascites using an angiosheath and conversion rate to other techniques after initial failure of making artificial ascites were evaluated. The technical success rate for RFA was assessed. In addition, potential factors associated with technical failure including previous history of transcatheter arterial chemoembolization (TACE) or RFA, type of abdominal surgery, and adjacent perihepatic structures were reviewed. Predictive factors for the technical failure of artificial ascites formation were analysed using multivariate analysis. The technical success rates of artificial ascites formation by angiosheath and that of RFA were 84.1% (95/113) and 97.3% (110/113), respectively. The conversion rate to other techniques after the failure of artificial ascites formation using an angiosheath was 15.9% (18/113). Previous hepatic resection was the sole independent predictive factor affecting the technical failure of artificial ascites formation (p<0.001, odds ratio = 29.03, 95% confidence interval: 4.56-184.69). Making artificial ascites for RFA of hepatic tumours using an angiosheath was technically feasible in most cases. However, history of hepatic resection was a significant predictive factor affecting the technical failure of artificial ascites formation. Copyright © 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Glycoconjugate Oxime Formation Catalyzed at Neutral pH: Mechanistic Insights and Applications of 1,4-Diaminobenzene as a Superior Catalyst for Complex Carbohydrates.

PubMed

Østergaard, Mads; Christensen, Niels Johan; Hjuler, Christian T; Jensen, Knud J; Thygesen, Mikkel B

2018-04-18

The reaction of unprotected carbohydrates with aminooxy reagents to provide oximes is a key method for the construction of glycoconjugates. Aniline and derivatives serve as organocatalysts for the formation of oximes from simple aldehydes, and we have previously reported that aniline also catalyzes the formation of oximes from the more complex aldehydes, carbohydrates. Here, we present a comprehensive study of the effect of aniline analogues on the formation of carbohydrate oximes and related glycoconjugates depending on organocatalyst structure, pH, nucleophile, and carbohydrate, covering more than 150 different reaction conditions. The observed superiority of the 1,4-diaminobenzene (PDA) catalyst at neutral pH is rationalized by NMR analyses and DFT studies of reaction intermediates. Carbohydrate oxime formation at pH 7 is demonstrated by the formation of a bioactive glycoconjugate from a labile, decorated octasaccharide originating from exopolysaccharides of the soil bacterium Mesorhizobium loti. This study of glycoconjugate formation includes the first direct comparison of aniline-catalyzed reaction rates and equilibrium constants for different classes of nucleophiles, including primary oxyamines, secondary N-alkyl oxyamines, as well as aryl and arylsulfonyl hydrazides. We identified 1,4-diaminobenzene as a superior catalyst for the construction of oxime-linked glycoconjugates under mild conditions.

Heating hydrocarbon containing formations in a spiral startup staged sequence

DOEpatents

Vinegar, Harold J [Bellaire, TX; Miller, David Scott [Katy, TX

2009-12-15

Methods for treating a hydrocarbon containing formation are described herein. Methods may include treating a first zone of the formation. Treatment of a plurality of zones of the formation may be begun at selected times after the treatment of the first zone begins. The treatment of at least two successively treated zones may begin at a selected time after treatment of the previous zone begins. At least two of the successively treated zones may be adjacent to the zone treated previously. The successive treatment of the zones proceeds in an outward, substantially spiral sequence from the first zone so that the treatment of the zones may move substantially spirally outwards towards a boundary of the treatment area.

Inhibitors of biofilm formation by fuel ethanol contaminants

USDA-ARS?s Scientific Manuscript database

Industrial fuel ethanol production suffers from chronic and acute infections that reduce yields and cause “stuck fermentations” that result in costly shutdowns. Lactic acid bacteria, particularly Lactobacillus sp., are recognized as major contaminants. In previous studies, we observed that certain...

Heat stress enhances LTM formation in Lymnaea: role of HSPs and DNA methylation.

PubMed

Sunada, Hiroshi; Riaz, Hamza; de Freitas, Emily; Lukowiak, Kai; Swinton, Cayley; Swinton, Erin; Protheroe, Amy; Shymansky, Tamila; Komatsuzaki, Yoshimasa; Lukowiak, Ken

2016-05-01

Environmentally relevant stressors alter the memory-forming process in Lymnaea following operant conditioning of aerial respiration. One such stressor is heat. Previously, we found that following a 1 h heat shock, long-term memory (LTM) formation was enhanced. We also had shown that the heat stressor activates at least two heat shock proteins (HSPs): HSP40 and HSP70. Here, we tested two hypotheses: (1) the production of HSPs is necessary for enhanced LTM formation; and (2) blocking DNA methylation prevents the heat stressor-induced enhancement of LTM formation. We show here that the enhancing effect of the heat stressor on LTM formation occurs even if snails experienced the stressor 3 days previously. We further show that a flavonoid, quercetin, which inhibits HSP activation, blocks the enhancing effect of the heat stressor on LTM formation. Finally, we show that injection of a DNA methylation blocker, 5-AZA, before snails experience the heat stressor prevents enhancement of memory formation. © 2016. Published by The Company of Biologists Ltd.

Genetic interaction of Neuroglian and Semaphorin1a during guidance and synapse formation.

PubMed

Godenschwege, Tanja A; Murphey, Rodney K

2009-01-01

We have previously demonstrated a function for Neuroglian and Semaphorin1a in Drosophila giant fiber circuit formation. Both molecules are required for guiding the giant fibers out of the brain and have distinct functions during giant synapse formation. In this study we characterized the effects of various combinations of Neuroglian and Semaphorin1a gain and loss of function backgrounds on giant fiber circuitry formation. We found that Neuroglian and Semaphorin1a genetically interact with each other during axon guidance as well as during synapse formation. Our experiments revealed that during pathfinding of the giant fibers out of the brain, Neuroglian function seems to be dependent on Semaphorin1a. In contrast, during giant fiber synapse formation we observed that Semaphorin1a signaling as a receptor can be altered by Neuroglian in the same cell. In summary, our findings suggest that Neuroglian and Semaphorin1a can regulate each other's function in cis and that the resultant signaling output is possibly different during guidance and synapse formation.

Evidence for Formation of a Radical-Mediated Flavin-N5 Covalent Intermediate.

PubMed

Dai, Yumin; Valentino, Hannah R; Sobrado, Pablo

2018-05-18

The redox-neutral reaction catalyzed by 2-haloacrylate hydratase (2-HAH) leads to the conversion of 2-chloroacrylate to pyruvate. Previous mechanistic studies demonstrated formation of a flavin-iminium ion as an important intermediate in the 2-HAH catalytic cycle. Time-resolved flavin absorbance studies were performed in this study and the data showed that the enzyme is capable of stabilizing both anionic and neutral flavin semiquinone species. The presence of a radical scavenger decreases the activity in a concentration-dependent manner. These data are consistent with the flavin iminium intermediate occurring via radical recombination. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Substantial convection and precipitation enhancements by ultrafine aerosol particles

NASA Astrophysics Data System (ADS)

Fan, Jiwen; Rosenfeld, Daniel; Zhang, Yuwei; Giangrande, Scott E.; Li, Zhanqing; Machado, Luiz A. T.; Martin, Scot T.; Yang, Yan; Wang, Jian; Artaxo, Paulo; Barbosa, Henrique M. J.; Braga, Ramon C.; Comstock, Jennifer M.; Feng, Zhe; Gao, Wenhua; Gomes, Helber B.; Mei, Fan; Pöhlker, Christopher; Pöhlker, Mira L.; Pöschl, Ulrich; de Souza, Rodrigo A. F.

2018-01-01

Ultrafine aerosol particles (smaller than 50 nanometers in diameter) have been thought to be too small to affect cloud formation. Fan et al. show that this is not the case. They studied the effect of urban pollution transported into the otherwise nearly pristine atmosphere of the Amazon. Condensational growth of water droplets around the tiny particles releases latent heat, thereby intensifying atmospheric convection. Thus, anthropogenic ultrafine aerosol particles may exert a more important influence on cloud formation processes than previously believed.

Evolutionary dynamics of group formation.

PubMed

Javarone, Marco Alberto; Marinazzo, Daniele

2017-01-01

Group formation is a quite ubiquitous phenomenon across different animal species, whose individuals cluster together forming communities of diverse size. Previous investigations suggest that, in general, this phenomenon might have similar underlying reasons across the interested species, despite genetic and behavioral differences. For instance improving the individual safety (e.g. from predators), and increasing the probability to get food resources. Remarkably, the group size might strongly vary from species to species, e.g. shoals of fishes and herds of lions, and sometimes even within the same species, e.g. tribes and families in human societies. Here we build on previous theories stating that the dynamics of group formation may have evolutionary roots, and we explore this fascinating hypothesis from a purely theoretical perspective, with a model using the framework of Evolutionary Game Theory. In our model we hypothesize that homogeneity constitutes a fundamental ingredient in these dynamics. Accordingly, we study a population that tries to form homogeneous groups, i.e. composed of similar agents. The formation of a group can be interpreted as a strategy. Notably, agents can form a group (receiving a 'group payoff'), or can act individually (receiving an 'individual payoff'). The phase diagram of the modeled population shows a sharp transition between the 'group phase' and the 'individual phase', characterized by a critical 'individual payoff'. Our results then support the hypothesis that the phenomenon of group formation has evolutionary roots.

Individual Factors and Successful Learning in a Hybrid Course

ERIC Educational Resources Information Center

Arispe, Kelly; Blake, Robert J.

2012-01-01

What personality factors make for a successful hybrid L2 learning experience? While previous studies have examined online learning in comparative terms (i.e. Which format is better: in class or hybrid?), this study examines certain personality and cognitive factors that might define the ideal hybrid language learner. All informants studied…

Short Animation Movies as Advance Organizers in Physics Teaching: A Preliminary Study

ERIC Educational Resources Information Center

Koscianski, Andre; Ribeiro, Rafael Joao; da Silva, Sani Carvalho Rutz

2012-01-01

Background: Advance organizers are instructional materials that help students use previous knowledge to make links with new information. Short animation movies are a possible format and are well suited for physics, as they can portray dynamic phenomena and represent abstract concepts. Purpose: The study aimed to determine guidelines for the…

DETERMINATION OF APPARENT QUANTUM YIELD SPECTRA FOR THE FORMATION OF BIOLOGICALLY LABILE PHOTOPRODUCTS

EPA Science Inventory

Quantum yield spectra for the photochemical formation of biologically labile photoproducts from dissolved organic matter (DOM) have not been available previously, although they would greatly facilitate attempts to model photoproduct formation rates across latitudinal, seasonal, a...

Mitochondrial impacts of insecticidal formate esters in insecticide-resistant and insecticide-susceptible Drosophila melanogaster.

PubMed

Song, Cheol; Scharf, Michael E

2009-06-01

Previous research on insecticidal formate esters in flies and mosquitoes has documented toxicity profiles, metabolism characteristics and neurological impacts. The research presented here investigated mitochondrial impacts of insecticidal formate esters and their hydrolyzed metabolite formic acid in the model dipteran insect Drosophila melanogaster Meig. These studies compared two Drosophila strains: an insecticide-susceptible strain (Canton-S) and a strain resistant by cytochrome P450 overexpression (Hikone-R). In initial studies investigating inhibition of mitochondrial cytochrome c oxidase, two proven insecticidal materials (hydramethylnon and sodium cyanide) caused significant inhibition. However, for insecticidal formate esters and formic acid, no significant inhibition was identified in either fly strain. Mitochondrial impacts of formate esters were then investigated further by tracking toxicant-induced cytochrome c release from mitochondria into the cytoplasm, a biomarker of apoptosis and neurological dysfunction. Formic acid and three positive control treatments (rotenone, antimycin A and sodium cyanide) induced cytochrome c release, verifying that formic acid is capable of causing mitochondrial disruption. However, when comparing formate ester hydrolysis and cytochrome c release between Drosophila strains, formic acid liberation was only weakly correlated with cytochrome c release in the susceptible Canton-S strain (r(2) = 0.70). The resistant Hikone-R strain showed no correlation (r(2) < 0.0001) between formate ester hydrolysis and cytochrome c release. The findings of this study provide confirmation of mitochondrial impacts by insecticidal formate esters and suggest links between mitochondrial disruption, respiratory inhibition, apoptosis and formate-ester-induced neurotoxicity.

Ozone production in remote oceanic and industrial areas derived from ship based measurements of peroxy radicals during TexAQS 2006

NASA Astrophysics Data System (ADS)

Sommariva, R.; Brown, S. S.; Roberts, J. M.; Brookes, D. M.; Parker, A. E.; Monks, P. S.; Bates, T. S.; Bon, D.; de Gouw, J. A.; Frost, G. J.; Gilman, J. B.; Goldan, P. D.; Herndon, S. C.; Kuster, W. C.; Lerner, B. M.; Osthoff, H. D.; Tucker, S. C.; Warneke, C.; Williams, E. J.; Zahniser, M. S.

2011-03-01

During the Texas Air Quality Study II (TexAQS 2006) campaign, a PEroxy Radical Chemical Amplifier (PERCA) was deployed on the NOAA research vessel R/V Brown to measure total peroxy radicals (HO2+Σ RO2). Day-time mixing ratios of HO2+Σ RO2 between 25 and 110 ppt were observed throughout the study area - the Houston/Galveston region and the Gulf coast of the US - and analyzed in relation to measurements of nitrogen oxides, volatile organic compounds (VOC) and photolysis rates to assess radical sources and sinks in the region. The measurements of HO2+Σ RO2 were used to calculate the in-situ net photochemical formation of ozone. Measured median values ranged from 0.6 ppb/h in clean oceanic air masses up to several tens of ppb/h in the most polluted industrial areas. The results are consistent with previous studies and generally agree with observations made during the previous TexAQS 2000 field campaign. The net photochemical ozone formation rates determined at Barbours Cut, a site immediately south of the Houston Ship Channel, were analyzed in relation to local wind direction and VOC reactivity to understand the relationship between ozone formation and local VOC emissions. The measurements of HO2+Σ RO2 made during the R/V Brown TexAQS 2006 cruise indicate that ozone formation is NOx-limited in the Houston/Galveston region and influenced by highly reactive hydrocarbons, especially alkenes from urban and industrial sources and their photo-oxidation products, such as formaldehyde.

Ozone production in remote oceanic and industrial areas derived from ship based measurements of peroxy radicals during TexAQS 2006

NASA Astrophysics Data System (ADS)

Sommariva, R.; Brown, S. S.; Roberts, J. M.; Brookes, D. M.; Parker, A. E.; Monks, P. S.; Bates, T. S.; Bon, D.; de Gouw, J. A.; Frost, G. J.; Gilman, J. B.; Goldan, P. D.; Herndon, S. C.; Kuster, W. C.; Lerner, B. M.; Osthoff, H. D.; Tucker, S. C.; Warneke, C.; Williams, E. J.; Zahniser, M. S.

2010-10-01

During the Texas Air Quality Study II (TexAQS 2006) campaign, a PEroxy Radical Chemical Amplifier (PERCA) was deployed on the NOAA research vessel R/V Brown to measure total peroxy radicals (HO2+ΣRO2). Day-time mixing ratios of HO2+ΣRO2 between 25 and 110 ppt were observed throughout the study area - the Houston/Galveston region and the Gulf coast of the U.S. - and analyzed in relation to measurements of nitrogen oxides, volatile organic compounds (VOC) and photolysis rates to assess radical sources and sinks in the region. The measurements of HO2+ΣRO2 were used to calculate the in-situ net photochemical formation of ozone. Measured median values ranged from 0.6 ppb/h in clean oceanic air masses up to several tens of ppb/h in the most polluted industrial areas. The results are consistent with previous studies and generally agree with observations made during the previous TexAQS 2000 field campaign. The net photochemical ozone formation rates determined at Barbours Cut, a site immediately south of the Houston Ship Channel, were analyzed in relation to local wind direction and VOC reactivity to understand the relationship between ozone formation and local VOC emissions. The measurements of HO2+ΣRO2 made during the R/V Brown TexAQS 2006 cruise indicate that ozone formation is NOx-limited in the Houston/Galveston region and influenced by highly reactive hydrocarbons, especially alkenes from urban and industrial sources and their photooxidation products, such as formaldehyde.

Ordovician and Silurian Phi Kappa and Trail Creek formations, Pioneer Mountains, central Idaho; stratigraphic and structural revisions, and new data on graptolite faunas

USGS Publications Warehouse

Dover, James H.; Berry, William B.N.; Ross, Reuben James

1980-01-01

Recent geologic mapping in the northern Pioneer Mountains combined with the identification of graptolites from 116 new collections indicate that the Ordovician and Silurian Phi Kappa and Trail Creek Formations occur in a series of thrust-bounded slices within a broad zone of imbricate thrust faulting. Though confirming a deformational style first reported in a 1963 study by Michael Churkin, our data suggest that the complexity and regional extent of the thrust zone were not previously recognized. Most previously published sections of the Phi Kappa and Trail Creek Formations were measured across unrecognized thrust faults and therefore include not only structural repetitions of graptolitic Ordovician and Silurian rocks but also other tectonically juxtaposed lithostratigraphic units of diverse ages as well. Because of this discovery, the need to reconsider the stratigraphic validity of these formations and their lithology, nomenclature, structural distribution, facies relations, and graptolite faunas has arisen. The Phi Kappa Formation in most thrust slices has internal stratigraphic continuity despite the intensity of deformation to which it was subjected. As revised herein, the Phi Kappa Formation is restricted to a structurally repeated succession of predominantly black, carbonaceous, graptolitic argillite and shale. Some limy, light-gray-weathering shale occurs in the middle part of the section, and fine-grained locally pebbly quartzite is present at the base. The basal quartzite is here named the Basin Gulch Quartzite Member of the Phi Kappa. The Phi Kappa redefined on a lithologic basis represents the span of Ordovician time from W. B. N. Berry's graptolite zones 2-4 through 15 and also includes approximately 17 m of lithologically identical shale of Early and Middle Silurian age at the top. The lower contact of the formation as revised is tectonic. The Phi Kappa is gradationally overlain by the Trail Creek Formation as restricted herein. Most of the coarser clastic rocks reported in previously measured sections of the Phi Kappa, as well as the sequence along Phi Kappa Creek from which the name originates, are excluded from the Phi Kappa as revised and are reassigned to two structural plates of Mississippian Copper Basin Formation; other strata now excluded from the formation are reassigned to the Trail Creek Formation and to an unnamed Silurian and Devonian unit. As redefined, the Phi Kappa Formation is only about 240 m thick, compared with the 3,860 m originally estimated, and it occupies only about 25 percent of the outcrop area previously mapped in 1930 by H. G. Westgate and C. P. Ross. Despite this drastic reduction in thickness and the exclusion of the rocks along Phi Kappa Creek, the name Phi Kappa is retained because of widely accepted prior usage to denote the Ordovician graptolitic shale facies of central Idaho, and because the Phi Kappa Formation as revised is present in thrust slices on Phi Kappa Mountain, at the head of Phi Kappa Creek. The lithic and faunal consistency of this unit throughout the area precludes the necessity for major facies telescoping along individual faults within the outcrop belt. However, tens of kilometers of tectonic shortening seems required to juxtapose the imbricated Phi Kappa shale facies with the Middle Ordovician part of the carbonate and quartzite shale sequence of east central Idaho. The shelf rocks are exposed in the Wildhorse structural window of the northeastern Pioneer Mountains, and attain a thickness of at least 1,500 m throughout the region north and east of the Pioneer Mountains. The Phi Kappa is in direct thrust contact on intensely deformed medium- to high-grade metamorphic equivalents of the same shelf sequence in the Pioneer window at the south end of the Phi Kappa-Trail Creek outcrop belt. Along East Pass, Big Lake, and Pine Creeks, north of the Pioneer Mountains, some rocks previously mapped as Ramshorn Slate are lithologically and faunally equivalent to the P

Sost deficiency does not alter bone's lacunar or vascular porosity in mice

NASA Astrophysics Data System (ADS)

Mosey, Henry; Núñez, Juan A.; Goring, Alice; Clarkin, Claire E.; Staines, Katherine A.; Lee, Peter D.; Pitsillides, Andrew A.; Javaheri, Behzad

2017-09-01

SCLEROSTIN (Sost) is expressed predominantly in osteocytes acting as a negative regulator of bone formation. In humans, mutations in the SOST gene lead to skeletal overgrowth and increased bone mineral density, suggesting that SCLEROSTIN is a key regulator of bone mass. The function of SCLEROSTIN as an inhibitor of bone formation is further supported by Sost knockout (KO) mice which display a high bone mass with elevated bone formation. Previous studies have indicated that Sost exerts its effect on bone formation through Wnt-mediated regulation of osteoblast differentiation, proliferation and activity. Recent in vitro studies have also suggested that SCLEROSTIN regulates angiogenesis and osteoblast-to-osteocyte transition. Despite this wealth of knowledge of the mechanisms responsible for SCLEROSTIN action, no previous studies have examined whether SCLEROSTIN regulates osteocyte and vascular configuration in cortices of mouse tibia. Herein, we image tibiae from Sost KO mice and their wild-type (WT) counterparts with high resolution CT to examine whether lack of SCLEROSTIN influences the morphometric properties of lacunae and vascular canal porosity relating to osteocytes and vessels within cortical bone. Male Sost KO and WT mice (n = 6 /group) were sacrificed at 12 weeks of age. Fixed tibiae were analysed using microCT to examine cortical bone mass and architecture. Then, samples were imaged by using benchtop and synchrotron nanoCT at the tibiofibular junction. Our data, consistent with previous studies show that, Sost deficiency leads to significant enhancement of bone mass by cortical thickening and bigger cross-sectional area and we find that this occurs without modifications of tibial ellipticity, a measure of bone shape. In addition, our data show that there are no significant differences in any lacunar or vascular morphometric or geometric parameters between Sost KO mouse tibia and WT counterparts. We therefore conclude that the significant increases in bone mass induced by Sost deficiency are not accompanied by any significant modification in the density, organisation or shape of osteocyte lacunae or vascular content within the cortical bone. These data may imply that SCLEROSTIN does not modify the frequency of osteocytogenic recruitment of osteoblasts to initiate terminal osteocytic differentiation in mice.

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

Medvedev, Ivan R.; De Lucia, Frank C.; Herbst, Eric

Since methyl formate (HCOOCH{sub 3}) is found to have a high abundance in hot molecular cores and other types of clouds in the galactic center, it is reasonable to search among such sources for detectable abundances of the more complex analog ethyl formate (HCOOC{sub 2}H{sub 5}). Following a previous study of the millimeter-wave spectrum of ethyl formate, we have extended the analysis of the vibrational ground state of the trans and gauche conformers of ethyl formate into the submillimeter-wave range. Over 2200 new spectral lines have been measured and analyzed at frequencies up to 380 GHz. Fitting the data formore » each conformer to a Watson A-reduced asymmetric-top Hamiltonian has allowed us to predict the frequencies and intensities of many more transitions through 380 GHz.« less

Beyond journal publications - a new format for the publication of clinical trials.

PubMed

Wieseler, Beate

2017-02-01

Journal publications are the major route to communicate methods and results of clinical trials. However, the shortcomings of this format are well known, including insufficient quality of the information provided as well as publication and outcome reporting bias. Attempts to improve the situation via peer review, reporting guidelines or study registration did not solve the problem. Currently, new ways of data presentation in electronic databases, increased access to previously confidential documents, and the potential use of anonymized individual patient data from clinical trials beyond the individual trial, have led to discussions about new publication formats for clinical trials. The current paper describes the components required for full information on a clinical trial and discusses a new format to provide this information. Copyright © 2016. Published by Elsevier GmbH.

A Molecular Copper Catalyst for Hydrogenation of CO­2 to Formate

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

Zall, Christopher M.; Linehan, John C.; Appel, Aaron M.

2015-09-04

There is widespread interest in the hydrogenation of CO2 to energy-rich products such as formate. However, first-row transition metal complexes that catalyze the hydrogenation of CO2 to formate remain rare. Copper phosphine complexes are widely used in the reduction of organic substrates but have not previously been used as catalysts for the conversion of H2 and CO2 to formate. Here we demonstrate that the triphosphine-ligated copper(I) complex LCu(MeCN)PF6 is an active catalyst for CO2 hydrogenation in the presence of a suitable base. Screening of bases and studies of catalytic reactions by in operando spectroscopy revealed important and unusual roles formore » the base in promoting H2 activation and turnover.« less

Leptin regulates bone formation via the sympathetic nervous system

NASA Technical Reports Server (NTRS)

Takeda, Shu; Elefteriou, Florent; Levasseur, Regis; Liu, Xiuyun; Zhao, Liping; Parker, Keith L.; Armstrong, Dawna; Ducy, Patricia; Karsenty, Gerard

2002-01-01

We previously showed that leptin inhibits bone formation by an undefined mechanism. Here, we show that hypothalamic leptin-dependent antiosteogenic and anorexigenic networks differ, and that the peripheral mediators of leptin antiosteogenic function appear to be neuronal. Neuropeptides mediating leptin anorexigenic function do not affect bone formation. Leptin deficiency results in low sympathetic tone, and genetic or pharmacological ablation of adrenergic signaling leads to a leptin-resistant high bone mass. beta-adrenergic receptors on osteoblasts regulate their proliferation, and a beta-adrenergic agonist decreases bone mass in leptin-deficient and wild-type mice while a beta-adrenergic antagonist increases bone mass in wild-type and ovariectomized mice. None of these manipulations affects body weight. This study demonstrates a leptin-dependent neuronal regulation of bone formation with potential therapeutic implications for osteoporosis.

The accelerating pace of star formation

NASA Astrophysics Data System (ADS)

Caldwell, Spencer; Chang, Philip

2018-03-01

We study the temporal and spatial distribution of star formation rates in four well-studied star-forming regions in local molecular clouds (MCs): Taurus, Perseus, ρ Ophiuchi, and Orion A. Using published mass and age estimates for young stellar objects in each system, we show that the rate of star formation over the last 10 Myr has been accelerating and is (roughly) consistent with a t2 power law. This is in line with previous studies of the star formation history of MCs and with recent theoretical studies. We further study the clustering of star formation in the Orion nebula cluster. We examine the distribution of young stellar objects as a function of their age by computing an effective half-light radius for these young stars subdivided into age bins. We show that the distribution of young stellar objects is broadly consistent with the star formation being entirely localized within the central region. We also find a slow radial expansion of the newly formed stars at a velocity of v = 0.17 km s-1, which is roughly the sound speed of the cold molecular gas. This strongly suggests the dense structures that form stars persist much longer than the local dynamical time. We argue that this structure is quasi-static in nature and is likely the result of the density profile approaching an attractor solution as suggested by recent analytic and numerical analysis.

CAPRICE positively regulates stomatal formation in the Arabidopsis hypocotyl

PubMed Central

2008-01-01

In the Arabidopsis hypocotyl, stomata develop only from a set of epidermal cell files. Previous studies have identified several negative regulators of stomata formation. Such regulators also trigger non-hair cell fate in the root. Here, it is shown that TOO MANY MOUTHS (TMM) positively regulates CAPRICE (CPC) expression in differentiating stomaless-forming cell files, and that the CPC protein might move to the nucleus of neighbouring stoma-forming cells, where it promotes stomata formation in a redundant manner with TRIPTYCHON (TRY). Unexpectedly, the CPC protein was also localized in the nucleus and peripheral cytoplasm of hypocotyl fully differentiated epidermal cells, suggesting that CPC plays an additional role to those related to stomata formation. These results identify CPC and TRY as positive regulators of stomata formation in the embryonic stem, which increases the similarity between the genetic control of root hair and stoma cell fate determination. PMID:19513241

Optical Basicity and Nepheline Crystallization in High Alumina Glasses

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

Rodriguez, Carmen P.; McCloy, John S.; Schweiger, M. J.

2011-02-25

The purpose of this study was to find compositions that increase waste loading of high-alumina wastes beyond what is currently acceptable while avoiding crystallization of nepheline (NaAlSiO4) on slow cooling. Nepheline crystallization has been shown to have a large impact on the chemical durability of high-level waste glasses. It was hypothesized that there would be some composition regions where high-alumina would not result in nepheline crystal production, compositions not currently allowed by the nepheline discriminator. Optical basicity (OB) and the nepheline discriminator (ND) are two ways of describing a given complex glass composition. This report presents the theoretical and experimentalmore » basis for these models. They are being studied together in a quadrant system as metrics to explore nepheline crystallization and chemical durability as a function of waste glass composition. These metrics were calculated for glasses with existing data and also for theoretical glasses to explore nepheline formation in Quadrant IV (passes OB metric but fails ND metric), where glasses are presumed to have good chemical durability. Several of these compositions were chosen, and glasses were made to fill poorly represented regions in Quadrant IV. To evaluate nepheline formation and chemical durability of these glasses, quantitative X-ray diffraction (XRD) analysis and the Product Consistency Test were conducted. A large amount of quantitative XRD data is collected here, both from new glasses and from glasses of previous studies that had not previously performed quantitative XRD on the phase assemblage. Appendix A critically discusses a large dataset to be considered for future quantitative studies on nepheline formation in glass. Appendix B provides a theoretical justification for choice of the oxide coefficients used to compute the OB criterion for nepheline formation.« less

Separate Ways: The Mass–Metallicity Relation Does Not Strongly Correlate with Star Formation Rate in SDSS-IV MaNGA Galaxies

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

Barrera-Ballesteros, J. K.; Heckman, T.; Sánchez, S. F.

We present the integrated stellar mass–metallicity relation (MZR) for more than 1700 galaxies included in the integral field area SDSS-IV MaNGA survey. The spatially resolved data allow us to determine the metallicity at the same physical scale (effective radius, R {sub eff}) using a heterogeneous set of 10 abundance calibrators. In addition to scale factors, the shape of the MZR is similar for all calibrators, consistent with those reported previously using single-fiber and integral field spectroscopy. We compare the residuals of this relation against the star formation rate (SFR) and specific SFR (sSFR). We do not find a strong secondarymore » relation of the MZR with either SFR or sSFR for any of the calibrators, in contrast with previous single-fiber spectroscopic studies. Our results agree with a scenario in which metal enrichment happens at local scales, with global outflows playing a secondary role in shaping the chemistry of galaxies and cold-gas inflows regulating the stellar formation.« less

Local induction of calcium phosphate formation on TiO2 coatings on titanium via surface treatment with a CO2 laser.

PubMed

Moritz, N; Jokinen, M; Peltola, T; Areva, S; Yli-Urpo, A

2003-04-01

Sol-gel-derived TiO(2) coatings are known to promote bonelike hydroxyapatite formation on their surfaces in vitro and in vivo. Hydroxyapatite integrates into bone tissue. In some clinical applications, the surface of an implant is simultaneously interfaced with soft and hard tissues, so it should match the properties of both. A new method is introduced for treating the coatings locally in a controlled manner. The local densification of sol-gel-derived titania coatings on titanium substrates with a CO(2) laser was studied in terms of the in vitro calcium phosphate-inducting properties. CO(2)-laser-treated multilayer coatings were compared with furnace-fired coatings prepared with the same recipe and previously shown to be bioactive. Additionally, local areas of furnace-fired multilayer coatings (previously shown to be bioactive in vitro) were further laser-treated to achieve various properties in the same implant. Topological surface properties were examined with atomic force microscopy. The formation of hydroxyapatite was studied with Fourier transform infrared and scanning electron microscopy energy-dispersive X-ray analysis. The results show that calcium phosphate formation can be adjusted locally by laser treatment. Calcium phosphate is a bonelike hydroxyapatite. The local treatment of sol-gel-derived coatings with a CO(2) laser is a promising technique for creating implants with various properties to interface different tissues and a possible way of coating implants that do not tolerate furnace firing. Copyright 2003 Wiley Periodicals, Inc.

AN INTERDISCIPLINARY APPROACH TO RIPARIAN MEADOW CHARACTERIZATION AND PRIORITIZATION, CENTRAL GREAT BASIN

EPA Science Inventory

The Great Basin Ecosystem Management Research group has described the hydrological, geophysical, and geomorphic conditions that lead to the formation and maintenance of riparian meadows of central Nevada. Previous work on these systems has focused on understanding a few study mea...

Anthropogenic pollution elevates the peak height of new particle formation from planetary boundary layer to lower free troposphere

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

Quan, Jiannong; Liu, Yangang; Liu, Quan

New particle formation (NPF) and subsequent growth are primary sources of atmospheric aerosol particles and cloud condensation nuclei. Previous studies have been conducted in relatively clean environments; investigation of NPF events over highly polluted megacities is still lacking. Here in this paper we show, based on a recent yearlong aircraft campaign conducted over Beijing, China, from April 2011 to June 2012, that NPF occurrence peaks in the lower free troposphere (LT), instead of planetary boundary layer (PBL), as most previous studies have found and that the distance of NPF peak to PBL top increases with increasing aerosol loading. Further analysismore » reveals that increased aerosols suppress NPF in PBL, but enhance NPF in LT due to a complex chain of aerosol-radiation-photochemistry interactions that affect both NPF sources and sinks. These findings shed new light on our understanding of NPF occurrence, NPF vertical distribution, and thus their effects on atmospheric photochemistry, clouds, and climate.« less

Anthropogenic pollution elevates the peak height of new particle formation from planetary boundary layer to lower free troposphere

DOE PAGES

Quan, Jiannong; Liu, Yangang; Liu, Quan; ...

2017-07-21

New particle formation (NPF) and subsequent growth are primary sources of atmospheric aerosol particles and cloud condensation nuclei. Previous studies have been conducted in relatively clean environments; investigation of NPF events over highly polluted megacities is still lacking. Here in this paper we show, based on a recent yearlong aircraft campaign conducted over Beijing, China, from April 2011 to June 2012, that NPF occurrence peaks in the lower free troposphere (LT), instead of planetary boundary layer (PBL), as most previous studies have found and that the distance of NPF peak to PBL top increases with increasing aerosol loading. Further analysismore » reveals that increased aerosols suppress NPF in PBL, but enhance NPF in LT due to a complex chain of aerosol-radiation-photochemistry interactions that affect both NPF sources and sinks. These findings shed new light on our understanding of NPF occurrence, NPF vertical distribution, and thus their effects on atmospheric photochemistry, clouds, and climate.« less

Membrane nanotubes in myeloid cells in the adult mouse cornea represent a novel mode of immune cell interaction.

PubMed

Seyed-Razavi, Yashar; Hickey, Michael J; Kuffová, Lucia; McMenamin, Paul G; Chinnery, Holly R

2013-01-01

Membrane nanotubes (MNTs) are newly discovered cellular extensions that are either blind-ended or can connect widely separated cells. They have predominantly been investigated in cultured isolated cells, however, previously we were the first group to demonstrate the existence of these structures in vivo in intact mammalian tissues. We previously demonstrated the frequency of both cell-cell or bridging MNTs and blind-ended MNTs was greatest between major histocompatibility complex (MHC) class II(+) cells during corneal injury or TLR ligand-mediated inflammation. The present study aimed to further explore the dynamics of MNT formation and their size, presence in another tissue, the dura mater, and response to stress factors and an active local viral infection of the murine cornea. Confocal live cell imaging of myeloid-derived cells in inflamed corneal explants from Cx(3)cr1(GFP) and CD11c(eYFP) transgenic mice revealed that MNTs form de novo at a rate of 15.5 μm/min. This observation contrasts with previous studies that demonstrated that in vitro these structures originate from cell-cell contacts. Conditions that promote formation of MNTs include inflammation in vivo and cell stress due to serum starvation ex vivo. Herpes simplex virus-1 infection did not cause a significant increase in MNT numbers in myeloid cells in the cornea above that observed in injury controls, confirming that corneal epithelium injury alone elicits MNT formation in vivo. These novel observations extend the currently limited understanding of MNTs in live mammalian tissues.

Impacts of Spontaneous Hot Flow Anomalies on the Magnetosheath and Magnetopause

NASA Technical Reports Server (NTRS)

Omidi, N.; Berchem, J.; Sibeck, D.; Zhang, H.

2016-01-01

Spacecraft observations and global hybrid (kinetic ions and fluid electrons) simulations have demonstrated that ion dissipation processes at the quasi-parallel bow shock are associated with the formation of structures called spontaneous hot flow anomalies (SHFAs). Previous simulations and recent spacecraft observations have also established that SHFAs result in the formation of magnetosheath filamentary structures(MFS). In this paper we demonstrate that in addition to MFS, SHFAs also result in the formation of magnetos heath cavities that are associated with decreases in density, velocity, and magnetic field and enhancements in temperature. We use the results of a global MHD run to determine the change in the magnetosheath properties associated with cavities due to ion kinetic effects. The results also show the formation of regions of high flow speed called magnetosheath jets whose properties as a function of solar wind Mach number are described in this study. Comparing the properties of the simulated magnetosheath cavities and jets to past spacecraft observations provides good agreement in both cases. We also demonstrate that pressure variations associated with cavities and SHFAs in the sheath result in a continuous sunward and anti sunward magnetopause motion. This result is consistent with previous suggestions that SHFAs may be responsible for the generation of ion cyclotron waves and precipitation of ring current protons in the outer magnetosphere.

The agencies method for coalition formation in experimental games

PubMed Central

Nash, John F.; Nagel, Rosemarie; Ockenfels, Axel; Selten, Reinhard

2012-01-01

In society, power is often transferred to another person or group. A previous work studied the evolution of cooperation among robot players through a coalition formation game with a non-cooperative procedure of acceptance of an agency of another player. Motivated by this previous work, we conduct a laboratory experiment on finitely repeated three-person coalition formation games. Human players with different strength according to the coalition payoffs can accept a transfer of power to another player, the agent, who then distributes the coalition payoffs. We find that the agencies method for coalition formation is quite successful in promoting efficiency. However, the agent faces a tension between short-term incentives of not equally distributing the coalition payoff and the long-term concern to keep cooperation going. In a given round, the strong player in our experiment often resolves this tension approximately in line with the Shapley value and the nucleolus. Yet aggregated over all rounds, the payoff differences between players are rather small, and the equal division of payoffs predicts about 80% of all groups best. One reason is that the voting procedure appears to induce a balance of power, independent of the individual player's strength: Selfish subjects tend to be voted out of their agency and are further disciplined by reciprocal behaviors. PMID:23175792

How desert varnish forms?

NASA Astrophysics Data System (ADS)

Perry, Randall S.; Kolb, Vera M.; Lynne, Bridget Y.; Sephton, Mark A.; Mcloughlin, Nicola; Engel, Michael H.; Olendzenski, Lorraine; Brasier, Martin; Staley, James T., Jr.

2005-09-01

Desert varnish is a black, manganese-rich rock coating that is widespread on Earth. The mechanism underlying its formation, however, has remained unresolved. We present here new data and an associated model for how desert varnish forms, which substantively challenges previously accepted models. We tested both inorganic processes (e.g. clays and oxides cementing coatings) and microbial methods of formation. Techniques used in this preliminary study include SEM-EDAX with backscatter, HRTEM of focused ion beam prepared (FIB) wafers and several other methods including XRPD, Raman spectroscopy, XPS and Tof-SIMS. The only hypothesis capable of explaining a high water content, the presence of organic compounds, an amorphous silica phase (opal-A) and lesser quantities of clays than previously reported, is a mechanism involving the mobilization and redistribution of silica. The discovery of silica in desert varnish suggests labile organics are preserved by interaction with condensing silicic acid. Organisms are not needed for desert varnish formation but Bacteria, Archaea, Eukarya, and other organic compounds are passively incorporated and preserved as organominerals. The rock coatings thus provide useful records of past environments on Earth and possibly other planets. Additionally this model also helps to explain the origin of key varnish and rock glaze features, including their hardness, the nature of the "glue" that binds heterogeneous components together, its layered botryoidal morphology, and its slow rate of formation.

The agencies method for coalition formation in experimental games.

PubMed

Nash, John F; Nagel, Rosemarie; Ockenfels, Axel; Selten, Reinhard

2012-12-11

In society, power is often transferred to another person or group. A previous work studied the evolution of cooperation among robot players through a coalition formation game with a non-cooperative procedure of acceptance of an agency of another player. Motivated by this previous work, we conduct a laboratory experiment on finitely repeated three-person coalition formation games. Human players with different strength according to the coalition payoffs can accept a transfer of power to another player, the agent, who then distributes the coalition payoffs. We find that the agencies method for coalition formation is quite successful in promoting efficiency. However, the agent faces a tension between short-term incentives of not equally distributing the coalition payoff and the long-term concern to keep cooperation going. In a given round, the strong player in our experiment often resolves this tension approximately in line with the Shapley value and the nucleolus. Yet aggregated over all rounds, the payoff differences between players are rather small, and the equal division of payoffs predicts about 80% of all groups best. One reason is that the voting procedure appears to induce a balance of power, independent of the individual player's strength: Selfish subjects tend to be voted out of their agency and are further disciplined by reciprocal behaviors.

Energetics of defects formation and oxygen migration in pyrochlore compounds from first principles calculations

NASA Astrophysics Data System (ADS)

Li, Yan; Kowalski, Piotr M.

2018-07-01

In order to get better understanding of the selective order-disorder transition in pyrochlore compounds, using ab initio methods we calculated the formation energies of coupled cation anti-site and anion Frenkel pair defects and the energy barriers for the oxygen migration for number of families of A2B2 O7 pyrochlore-type compounds. While these parameters have been previously computed with force field-based methods, the ab initio results provide more reliable values that can be confidently used in subsequent analysis. We found a fairly good correlation between the formation energies of the coupled defects and the stability field of pyrochlores. In line with previous studies, the compounds that crystallize in defect fluorite structure are found to have smaller values of coupled defect formation energies than those crystallizing in the pyrochlore phase, although the correlation is not that sharp as in the case of isolated anion Frenkel pair defect. The investigation of the energy barriers for the oxygen migration shows that it is not a good, sole indicator of the tendency of the order-disorder phase transition in pyrochlores. However, we found that the oxygen migration barrier is reduced in the presence of the cation antisite defect. This points at disordering-induced enhancement of oxygen diffusion in pyrochlore compounds.

Impacts of spontaneous hot flow anomalies on the magnetosheath and magnetopause

NASA Astrophysics Data System (ADS)

Omidi, N.; Berchem, J.; Sibeck, D.; Zhang, H.

2016-04-01

Spacecraft observations and global hybrid (kinetic ions and fluid electrons) simulations have demonstrated that ion dissipation processes at the quasi-parallel bow shock are associated with the formation of structures called spontaneous hot flow anomalies (SHFAs). Previous simulations and recent spacecraft observations have also established that SHFAs result in the formation of magnetosheath filamentary structures (MFS). In this paper we demonstrate that in addition to MFS, SHFAs also result in the formation of magnetosheath cavities that are associated with decreases in density, velocity, and magnetic field and enhancements in temperature. We use the results of a global MHD run to determine the change in the magnetosheath properties associated with cavities due to ion kinetic effects. The results also show the formation of regions of high flow speed called magnetosheath jets whose properties as a function of solar wind Mach number are described in this study. Comparing the properties of the simulated magnetosheath cavities and jets to past spacecraft observations provides good agreement in both cases. We also demonstrate that pressure variations associated with cavities and SHFAs in the sheath result in a continuous sunward and antisunward magnetopause motion. This result is consistent with previous suggestions that SHFAs may be responsible for the generation of ion cyclotron waves and precipitation of ring current protons in the outer magnetosphere.

Experimental Acid Weathering of Fe-Bearing Mars Analog Minerals and Rocks: Implications for Aqueous Origin of Hematite-Bearing Sediments in Meridiani Planum, Mars

NASA Technical Reports Server (NTRS)

Golden, D. C.; Koster, A. M.; Ming, D. W.; Morris, R. V.; Mertzman, S. A.

2011-01-01

A working hypothesis for Meridiani evaporite formation involves the evaporation of fluids derived from acid weathering of Martian basalts and subsequent diagenesis [1, 2]. However, there are no reported experimental studies for the formation of jarosite and gray hematite (spherules), which are characteristic of Meridiani rocks from Mars analog precursor minerals. A terrestrial analog for hematite spherule formation from basaltic rocks under acidic hydrothermal conditions has been reported [3], and we have previously shown that the hematite spherules and jarosite can be synthetically produced in the laboratory using Fe3+ -bearing sulfate brines under hydrothermal conditions [4]. Here we expand and extend these studies by reacting Mars analog minerals with sulfuric acid to form Meridiani-like rock-mineral compositions. The objective of this study is to provide environmental constraints on past aqueous weathering of basaltic materials on Mars.

Integration of altitude and airspeed information into a primary flight display via moving-tape formats: Evaluation during random tracking task

NASA Technical Reports Server (NTRS)

Abbott, Terence S.; Nataupsky, Mark; Steinmetz, George G.

1987-01-01

A ground-based aircraft simulation study was conducted to determine the effects on pilot preference and performance of integrating airspeed and altitude information into an advanced electronic primary flight display via moving-tape (linear moving scale) formats. Several key issues relating to the implementation of moving-tape formats were examined in this study: tape centering, tape orientation, and trend information. The factor of centering refers to whether the tape was centered about the actual airspeed or altitude or about some other defined reference value. Tape orientation refers to whether the represented values are arranged in descending or ascending order. Two pilots participated in this study, with each performing 32 runs along seemingly random, previously unknown flight profiles. The data taken, analyzed, and presented consisted of path performance parameters, pilot-control inputs, and electrical brain response measurements.

Space Shuttle Pinhole Formation Mechanism Studies

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.

1998-01-01

Pinholes have been observed to form on the wing leading edge of the space shuttle after about 10-15 flights. In this report we expand upon previous observations by Christensen (1) that these pinholes often form along cracks and are associated with a locally zinc-rich area. The zinc appears to come from weathering and peeling paint on the launch structure. Three types of experimental examinations are performed to understand this issue further: (A) Detailed microstructural examination of actual shuttle pinholes (B) Mass spectrometric studies of coupons containing, actual shuttle pinholes and (C) Laboratory furnace studies of ZnO/SiC reactions and ZnO/SiC protected carbon/carbon reaction. On basis of these observations we present a detailed mechanism of pinhole formation due to formation of a corrosive ZnO-Na-2-O-SiO2 ternary glass, which flows into existing cracks and enlarges them.

Synergistic Effects of Vascular Endothelial Growth Factor on Bone Morphogenetic Proteins Induced Bone Formation In Vivo: Influencing Factors and Future Research Directions

PubMed Central

Li, Bo; Wang, Hai; Qiu, Guixing; Su, Xinlin

2016-01-01

Vascular endothelial growth factor (VEGF) and bone morphogenetic proteins (BMPs), as key mediators in angiogenesis and osteogenesis, are used in a combined delivery manner as a novel strategy in bone tissue engineering. VEGF has the potential to enhance BMPs induced bone formation. Both gene delivery and material-based delivery systems were incorporated in previous studies to investigate the synergistic effects of VEGF and BMPs. However, their results were controversial due to variation of methods incorporated in different studies. Factors influencing the synergistic effects of VEGF on BMPs induced bone formation were identified and analyzed in this review to reduce confusion on this issue. The potential mechanisms and directions of future studies were also proposed here. Further investigating mechanisms of the synergistic effects and optimizing these influencing factors will help to generate more effective bone regeneration. PMID:28070506

Apyrase Elicits Host Antimicrobial Responses and Resolves Infection in Burns.

PubMed

Bayliss, Jill M; Levi, Benjamin; Wu, Jianfeng; Wang, Stewart C; Su, Grace L; Xi, Chuanwu

The authors previously reported that adenosine triphosphate (ATP) stimulates biofilm formation and removal of the ATP could reduce biofilm formation. The main objective of this study was to evaluate the effects of the ATP-hydrolyzing enzyme, apyrase, on control of Acinetabacter baumannii infection in the burn wound as well as to assess host skin antimicrobial responses. The authors found that apyrase stimulated nitric oxide formation at the wound site and reduced CD55 expression, thereby inducing the assembly of membrane attack complexes. Apyrase treatment nearly eradicated multidrug-resistant A. baumannii from burn wounds in the absence of antibiotics. Apyrase may be an effective therapy against antibiotic-resistant bacterial infections in burns.

Streptococcus sanguinis biofilm formation & interaction with oral pathogens.

PubMed

Zhu, Bin; Macleod, Lorna C; Kitten, Todd; Xu, Ping

2018-06-08

Caries and periodontitis are the two most common human dental diseases and are caused by dysbiosis of oral flora. Although commensal microorganisms have been demonstrated to protect against pathogens and promote oral health, most previous studies have addressed pathogenesis rather than commensalism. Streptococcus sanguinis is a commensal bacterium that is abundant in the oral biofilm and whose presence is correlated with health. Here, we focus on the mechanism of biofilm formation in S. sanguinis and the interaction of S. sanguinis with caries- and periodontitis-associated pathogens. In addition, since S. sanguinis is well known as a cause of infective endocarditis, we discuss the relationship between S. sanguinis biofilm formation and its pathogenicity in endocarditis.

The stellar mass, star formation rate and dark matter halo properties of LAEs at z ˜ 2

NASA Astrophysics Data System (ADS)

Kusakabe, Haruka; Shimasaku, Kazuhiro; Ouchi, Masami; Nakajima, Kimihiko; Goto, Ryosuke; Hashimoto, Takuya; Konno, Akira; Harikane, Yuichi; Silverman, John D.; Capak, Peter L.

2018-01-01

We present average stellar population properties and dark matter halo masses of z ˜ 2 Lyα emitters (LAEs) from spectral energy distribution fitting and clustering analysis, respectively, using ≃ 1250 objects (NB387≤25.5) in four separate fields of ≃ 1 deg2 in total. With an average stellar mass of 10.2 ± 1.8 × 108 M⊙ and star formation rate of 3.4 ± 0.4 M⊙ yr-1, the LAEs lie on an extrapolation of the star-formation main sequence (MS) to low stellar mass. Their effective dark matter halo mass is estimated to be 4.0_{-2.9}^{+5.1} × 10^{10}{ }M_{⊙} with an effective bias of 1.22^{+0.16}_{-0.18}, which is lower than that of z ˜ 2 LAEs (1.8 ± 0.3) obtained by a previous study based on a three times smaller survey area, with a probability of 96%. However, the difference in the bias values can be explained if cosmic variance is taken into account. If such a low halo mass implies a low H I gas mass, this result appears to be consistent with the observations of a high Lyα escape fraction. With the low halo masses and ongoing star formation, our LAEs have a relatively high stellar-to-halo mass ratio (SHMR) and a high efficiency of converting baryons into stars. The extended Press-Schechter formalism predicts that at z = 0 our LAEs are typically embedded in halos with masses similar to that of the Large Magellanic Cloud (LMC); they will also have similar SHMRs to the LMC, if their star formation rates are largely suppressed after z ˜ 2 as some previous studies have reported for the LMC itself.

Examination of an Administrator-Read Vocabulary-Matching Measure as an Indicator of Science Achievement

ERIC Educational Resources Information Center

Borsuk, Ellen R.

2010-01-01

Research and development of measures to document ongoing learning within the content areas are in the beginning stages. As such, the current study adds to efforts in the development of the vocabulary-matching measure. Using a modified format of the previously studied vocabulary-matching measure, 63 middle school students completed alternate forms…

Systematic study of α decay of nuclei around the Z =82 , N =126 shell closures within the cluster-formation model and proximity potential 1977 formalism

NASA Astrophysics Data System (ADS)

Deng, Jun-Gang; Zhao, Jie-Cheng; Chu, Peng-Cheng; Li, Xiao-Hua

2018-04-01

In the present work, we systematically study the α decay preformation factors Pα within the cluster-formation model and α decay half-lives by the proximity potential 1977 formalism for nuclei around Z =82 ,N =126 closed shells. The calculations show that the realistic Pα is linearly dependent on the product of valance protons (holes) and valance neutrons (holes) NpNn . It is consistent with our previous works [Sun et al., Phys. Rev. C 94, 024338 (2016), 10.1103/PhysRevC.94.024338; Deng et al., Phys. Rev. C 96, 024318 (2017), 10.1103/PhysRevC.96.024318], in which Pα are model dependent and extracted from the ratios of calculated α half-lives to experimental data. Combining with our previous works, we confirm that the valance proton-neutron interaction plays a key role in the α preformation for nuclei around Z =82 ,N =126 shell closures whether the Pα is model dependent or microcosmic. In addition, our calculated α decay half-lives by using the proximity potential 1977 formalism taking Pα evaluated by the cluster-formation model can well reproduce the experimental data and significantly reduce the errors.

Genetically modified haloes: towards controlled experiments in ΛCDM galaxy formation

NASA Astrophysics Data System (ADS)

Roth, Nina; Pontzen, Andrew; Peiris, Hiranya V.

2016-01-01

We propose a method to generate `genetically modified' (GM) initial conditions for high-resolution simulations of galaxy formation in a cosmological context. Building on the Hoffman-Ribak algorithm, we start from a reference simulation with fully random initial conditions, then make controlled changes to specific properties of a single halo (such as its mass and merger history). The algorithm demonstrably makes minimal changes to other properties of the halo and its environment, allowing us to isolate the impact of a given modification. As a significant improvement over previous work, we are able to calculate the abundance of the resulting objects relative to the reference simulation. Our approach can be applied to a wide range of cosmic structures and epochs; here we study two problems as a proof of concept. First, we investigate the change in density profile and concentration as the collapse times of three individual haloes are varied at fixed final mass, showing good agreement with previous statistical studies using large simulation suites. Secondly, we modify the z = 0 mass of haloes to show that our theoretical abundance calculations correctly recover the halo mass function. The results demonstrate that the technique is robust, opening the way to controlled experiments in galaxy formation using hydrodynamic zoom simulations.

Beneath the scaly clay and clay breccia of Karangsambung area

NASA Astrophysics Data System (ADS)

Arisbaya, Ilham; Handayani, Lina

2018-02-01

Karangsambung area, Central Java-Indonesia, records tectonic evolution of the western part of Sundaland margin. The area is thought to have undergone a long tectonic evolution from palaeosubduction, collision with the continental fragments of Gondwana, to the formation of the recent subduction zone. An interesting phenomenon in this area is the presence of the Late Cretaceous ophiolitic blocks with an east northeast (ENE) trending-direction surrounded by the east trend of Eocene - Oligocene sedimentary melange formation. There was also an ENE trending Dakah volcanic rocks unit found in this area, with approximately equivalent age with the sedimentary mélange formation. There are two main interpretations regarding this volcanic unit, as an olistostrome and as an insitu shallow subduction magmatic product. Detailed mechanism of the emplacement of the Late Cretaceous ophiolite and the genesis of the volcanic rocks unit and their implications to the regional tectonic model is still open for discussion. Geophysical research in this key area may help to reveal the geometry, relationship among rocks units, and tectonic evolution. Unfortunately, geophysical studies in this area are still lacking. Previous geophysical work in Karangsambung still leaves uncertainty, especially in depth control and spatial resolution issue. Here we describe the results of previous works in Karangsambung as basic knowledge for the upcoming geophysical study.

Kinetic theory of pattern formation in mixtures of microtubules and molecular motors

NASA Astrophysics Data System (ADS)

Maryshev, Ivan; Marenduzzo, Davide; Goryachev, Andrew B.; Morozov, Alexander

2018-02-01

In this study we formulate a theoretical approach, based on a Boltzmann-like kinetic equation, to describe pattern formation in two-dimensional mixtures of microtubular filaments and molecular motors. Following the previous work by Aranson and Tsimring [Phys. Rev. E 74, 031915 (2006), 10.1103/PhysRevE.74.031915] we model the motor-induced reorientation of microtubules as collision rules, and devise a semianalytical method to calculate the corresponding interaction integrals. This procedure yields an infinite hierarchy of kinetic equations that we terminate by employing a well-established closure strategy, developed in the pattern-formation community and based on a power-counting argument. We thus arrive at a closed set of coupled equations for slowly varying local density and orientation of the microtubules, and study its behavior by performing a linear stability analysis and direct numerical simulations. By comparing our method with the work of Aranson and Tsimring, we assess the validity of the assumptions required to derive their and our theories. We demonstrate that our approximation-free evaluation of the interaction integrals and our choice of a systematic closure strategy result in a rather different dynamical behavior than was previously reported. Based on our theory, we discuss the ensuing phase diagram and the patterns observed.

Comparing cosmological hydrodynamic simulations with observations of high- redshift galaxy formation

NASA Astrophysics Data System (ADS)

Finlator, Kristian Markwart

We use cosmological hydrodynamic simulations to study the impact of outflows and radiative feedback on high-redshift galaxies. For outflows, we consider simulations that assume (i) no winds, (ii) a "constant-wind" model in which the mass-loading factor and outflow speed are constant, and (iii) "momentum-driven" winds in which both parameters vary smoothly with mass. In order to treat radiative feedback, we develop a moment-based radiative transfer technique that operates in both post-processing and coupled radiative hydrodynamic modes. We first ask how outflows impact the broadband spectral energy distributions (SEDs) of six observed reionization-epoch galaxies. Simulations reproduce five regardless of the outflow prescription, while the sixth suggests an unusually bursty star formation history. We conclude that (i) simulations broadly account for available constraints on reionization-epoch galaxies, (ii) individual SEDs do not constrain outflows, and (iii) SED comparisons efficiently isolate objects that challenge simulations. We next study how outflows impact the galaxy mass metallicity relation (MZR). Momentum-driven outflows uniquely reproduce observations at z = 2. In this scenario, galaxies obey two equilibria: (i) The rate at which a galaxy processes gas into stars and outflows tracks its inflow rate; and (ii) The gas enrichment rate owing to star formation balances the dilution rate owing to inflows. Combining these conditions indicates that the MZR is dominated by the (instantaneous) variation of outflows with mass, with more-massive galaxies driving less gas into outflows per unit stellar mass formed. Turning to radiative feedback, we use post-processing simulations to study the topology of reionization. Reionization begins in overdensities and then "leaks" directly into voids, with filaments reionizing last owing to their high density and low emissivity. This result conflicts with previous findings that voids ionize last. We argue that it owes to the uniqely-biased emissivity field produced by our star formation prescriptions, which have previously been shown to reproduce numerous post-reionization constraints. Finally, preliminary results from coupled radiative hydrodynamic simulations indicate that reionization suppresses the star formation rate density by at most 10-20% by z = 5. This is much less than previous estimates, which we attribute to our unique reionization topology although confirmation will have to await more detailed modeling.

A Vertex Model of Drosophila Ventral Furrow Formation

PubMed Central

Spahn, Philipp; Reuter, Rolf

2013-01-01

Ventral furrow formation in Drosophila is an outstanding model system to study the mechanisms involved in large-scale tissue rearrangements. Ventral cells accumulate myosin at their apical sides and, while being tightly coupled to each other via apical adherens junctions, execute actomyosin contractions that lead to reduction of their apical cell surface. Thereby, a band of constricted cells along the ventral epithelium emerges which will form a tissue indentation along the ventral midline (the ventral furrow). Here we adopt a 2D vertex model to simulate ventral furrow formation in a surface view allowing easy comparison with confocal live-recordings. We show that in order to reproduce furrow morphology seen in vivo, a gradient of contractility must be assumed in the ventral epithelium which renders cells more contractile the closer they lie to the ventral midline. The model predicts previous experimental findings, such as the gain of eccentric morphology of constricting cells and an incremental fashion of apical cell area reduction. Analysis of the model suggests that this incremental area reduction is caused by the dynamical interplay of cell elasticity and stochastic contractility as well as by the opposing forces from contracting neighbour cells. We underpin results from the model through in vivo analysis of ventral furrow formation in wildtype and twi mutant embryos. Our results show that ventral furrow formation can be accomplished as a “tug-of-war” between stochastically contracting, mechanically coupled cells and may require less rigorous regulation than previously thought. Summary For the developmental biologist it is a fascinating question how cells can coordinate major tissue movements during embryonic development. The so-called ventral furrow of the Drosophila embryo is a well-studied example of such a process when cells from a ventral band, spanning nearly the entire length of the embryo, undergo dramatic shape change by contracting their tips and then fold inwards into the interior of the embryo. Although numerous genes have been identified that are critical for ventral furrow formation, it is an open question how cells work together to elicit this tissue rearrangement. We use a computational model to mimic the physical properties of cells in the ventral epithelium and simulate the formation of the furrow. We find that the ventral furrow can form through stochastic self-organisation and that previous experimental observations can be readily explained in our model by considering forces that arise when cells execute contractions while being coupled to each other in a mechanically coherent epithelium. The model highlights the importance of a physical perspective when studying tissue morphogenesis and shows that only a minimal genetic regulation may be required to drive complex processes in embryonic development. PMID:24066163

Starless Clumps and the Earliest Phases of High-mass Star Formation in the Milky Way

NASA Astrophysics Data System (ADS)

Svoboda, Brian

2018-01-01

High-mass stars are key to regulating the interstellar medium, star formation activity, and overall evolution of galaxies, but their formation remains an open problem in astrophysics. In order to understand the physical conditions during the earliest phases of high-mass star formation, I report on observational studies of dense starless clump candidates (SCCs) that show no signatures of star formation activity. I identify 2223 SCCs from the 1.1 mm Bolocam Galactic Plane Survey, systematically analyze their physical properties, and show that the starless phase is not represented by a single timescale, but evolves more rapidly with increasing clump mass. To investigate the sub-structure in SCCs at high spatial resolution, I study the 12 most high-mass SCCs within 5 kpc using ALMA. I report previously undetected low-luminosity protostars in 11 out of 12 SCCs, fragmentation equal to the thermal Jeans length of the clump, and no starless cores exceeding 30 solar masses. While uncertainties remain concerning the star formation effeciency in this sample, these observational facts are consistent with models where high-mass stars form from intially low- to intermediate-mass protostars that accrete most of their mass from the surrounding clump.

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

Janowiecki, Steven; Salzer, John J.; Zee, Liese van

We discuss and test possible evolutionary connections between blue compact dwarf galaxies (BCDs) and other types of dwarf galaxies. BCDs provide ideal laboratories to study intense star formation episodes in low-mass dwarf galaxies, and have sometimes been considered a short-lived evolutionary stage between types of dwarf galaxies. To test these connections, we consider a sample of BCDs as well as a comparison sample of nearby galaxies from the Local Volume Legacy (LVL) survey for context. We fit the multi-wavelength spectral energy distributions (SED, far-ultra-violet to far-infrared) of each galaxy with a grid of theoretical models to determine their stellar massesmore » and star formation properties. We compare our results for BCDs with the LVL galaxies to put BCDs in the context of normal galaxy evolution. The SED fits demonstrate that the star formation events currently underway in BCDs are at the extreme of the continuum of normal dwarf galaxies, both in terms of the relative mass involved and in the relative increase over previous star formation rates. Today’s BCDs are distinctive objects in a state of extreme star formation that is rapidly transforming them. This study also suggests ways to identify former BCDs whose star formation episodes have since faded.« less

Resolving molecular gas to ~500 pc in a unique star forming disk galaxy at z~2

NASA Astrophysics Data System (ADS)

Brisbin, Drew; Aravena, Manuel; Hodge, Jacqueline; Carilli, Chris Luke; Daddi, Emanuele; Dannerbauer, Helmut; Riechers, Dominik; Wagg, Jeff

2018-06-01

We have resolved molecular gas in a 'typical' star forming disk galaxy at z>2 down to the scale of ~500 pc. Previous observations of CO and [CI] lines on larger spatial scales have revealed bulk molecular and atomic gas properties indicating that the target is a massive disk galaxy with large gas reserves. Unlike many galaxies studied at high redshift, it is undergoing modest quiescent star formation rather than bursty centrally concentrated star formation. Therefore this galaxy represents an under-studied, but cosmologically important population in the early universe. Our new observations of CO (4-3) highlight the clumpy molecular gas fuelling star formation throughout the disk. Underlying continuum from cold dust provides a key constraint on star formation rate surface densities, allowing us to examine the star formation rate surface density scaling law in a never-before-tested regime of early universe galaxies.These observations enable an unprecedented view of the obscured star formation that is hidden to optical/UV imaging and trace molecular gas on a fine enough scale to resolve morphological traits and provide a view akin to single dish surveys in the local universe.

The effect of question format and task difficulty on reasoning strategies and diagnostic performance in Internal Medicine residents.

PubMed

Heemskerk, Laura; Norman, Geoff; Chou, Sophia; Mintz, Marcy; Mandin, Henry; McLaughlin, Kevin

2008-11-01

Previous studies have suggested an association between reasoning strategies and diagnostic success, but the influence on this relationship of variables such as question format and task difficulty, has not been studied. Our objective was to study the association between question format, task difficulty, reasoning strategies and diagnostic success. Study participants were 13 Internal Medicine residents at the University of Calgary. Each was given eight problem-solving questions in four clinical presentations and were randomized to groups that differed only in the question format, such that a question presented as short answer (SA) to the first group was presented as extended matching (EM) to the second group. There were equal numbers of SA/EM questions and straightforward/difficult tasks. Participants performed think-aloud during diagnostic reasoning. Data were analyzed using multiple logistic regression. Question format was associated with reasoning strategies; hypothetico-deductive reasoning being used more frequently on EM questions and scheme-inductive reasoning on SA questions. For SA question, non-analytic reasoning alone was used more frequently to answer straightforward cases than difficult cases, whereas for EM questions no such association was observed. EM format and straightforward task increased the odds of diagnostic success, whereas hypothetico-deductive reasoning was associated with reduced odds of success. Question format and task difficulty both influence diagnostic reasoning strategies and studies that examine the effect of reasoning strategies on diagnostic success should control for these effects. Further studies are needed to investigate the effect of reasoning strategies on performance of different groups of learners.

Cluster formation and percolation in ethanol-water mixtures

NASA Astrophysics Data System (ADS)

Gereben, Orsolya; Pusztai, László

2017-10-01

Results of systematic molecular dynamics studies of ethanol-water mixtures, over the entire concentration range, were reported previously that agree with experimental X-ray diffraction data. These simulated systems are analyzed in this work to examine cluster formation and percolation, using four different hydrogen bond definitions. Percolation analyses revealed that each mixture (even the one containing 80 mol% ethanol) is above the 3D percolation threshold, with fractal dimensions, df, between 2.6 and 2.9, depending on concentration. Monotype water cluster formation was also studied in the mixtures: 3D water percolation can be found in systems with less than 40 mol% ethanol, with fractal dimensions between 2.53 and 2.84. These observations can be put in parallel with experimental data on some thermodynamic quantities, such as the excess partial molar enthalpy and entropy.

Numerical Simulation of the Effect of 3D Needle Movement on Cavitation and Spray Formation in a Diesel Injector

NASA Astrophysics Data System (ADS)

Mandumpala Devassy, B.; Edelbauer, W.; Greif, D.

2015-12-01

Cavitation and its effect on spray formation and its dispersion play a crucial role in proper engine combustion and controlled emission. This study focuses on these effects in a typical common rail 6-hole diesel injector accounting for 3D needle movement and flow compressibility effects. Coupled numerical simulations using 1D and 3D CFD codes are used for this investigation. Previous studies in this direction have already presented a detailed structure of the adopted methodology. Compared to the previous analysis, the present study investigates the effect of 3D needle movement and cavitation on the spray formation for pilot and main injection events for a typical diesel engine operating point. The present setup performs a 3D compressible multiphase simulation coupled with a standalone 1D high pressure flow simulation. The simulation proceeds by the mutual communication between 1D and 3D solvers. In this work a typical common rail injector with a mini-sac nozzle is studied. The lateral and radial movement of the needle and its effect on the cavitation generation and the subsequent spray penetration are analyzed. The result indicates the effect of compressibility of the liquid on damping the needle forces, and also the difference in the spray penetration levels due to the asymmetrical flow field. Therefore, this work intends to provide an efficient and user-friendly engineering tool for simulating a complete fuel injector including spray propagation.

Inhibiting corticosterone synthesis during fear memory formation exacerbates cued fear extinction memory deficits within the single prolonged stress model.

PubMed

Keller, Samantha M; Schreiber, William B; Stanfield, Briana R; Knox, Dayan

2015-01-01

Using the single prolonged stress (SPS) animal model of post-traumatic stress disorder (PTSD), previous studies suggest that enhanced glucocorticoid receptor (GR) expression leads to cued fear extinction retention deficits. However, it is unknown how the endogenous ligand of GRs, corticosterone (CORT), may contribute to extinction retention deficits in the SPS model. Given that CORT synthesis during fear learning is critical for fear memory consolidation and SPS enhances GR expression, CORT synthesis during fear memory formation could strengthen fear memory in SPS rats by enhancing GR activation during fear learning. In turn, this could lead to cued fear extinction retention deficits. We tested the hypothesis that CORT synthesis during fear learning leads to cued fear extinction retention deficits in SPS rats by administering the CORT synthesis inhibitor metyrapone to SPS and control rats prior to fear conditioning, and observed the effect this had on extinction memory. Inhibiting CORT synthesis during fear memory formation in control rats tended to decrease cued freezing, though this effect never reached statistical significance. Contrary to our hypothesis, inhibiting CORT synthesis during fear memory formation disrupted extinction retention in SPS rats. This finding suggests that even though SPS exposure leads to cued fear extinction memory deficits, CORT synthesis during fear memory formation enhances extinction retention in SPS rats. This suggests that stress-induced CORT synthesis in previously stressed rats can be beneficial. Copyright © 2015 Elsevier B.V. All rights reserved.

Biostratigraphy and biochronology of the Monte Hermoso Formation (early Pliocene) at its type locality, Buenos Aires Province, Argentina

NASA Astrophysics Data System (ADS)

Tomassini, Rodrigo L.; Montalvo, Claudia I.; Deschamps, Cecilia M.; Manera, Teresa

2013-12-01

The Monte Hermoso Formation, cropping out at its type locality of Farola Monte Hermoso (Buenos Aires Province), is a classical fossiliferous unit of the South American Neogene, highlighted by the abundance and diversity of its vertebrate remains. However, its biostratigraphy and age have been largely debated, and numerous discrepancies and controversies have been stated. In this regard, the result of the analysis of new materials recovered from the different levels of this formation, following a strict control of stratigraphic provenance, is here reported. As well, the provenance of specimens of previous collections has been evaluated. The studied assemblage consists of Osteichthyes, Amphibia, Reptilia, Aves and Mammalia. These latter are the most numerous and belong to the Didelphimorphia, Polydolopimorphia, Rodentia, Notoungulata, Litopterna and Xenarthra. The recorded taxa suggest no important faunistic variations among the different levels of the Monte Hermoso Formation that would imply significant chronological differences, and hence, justify the recognition of two biostratigraphic units. The analysis of the first and last records as well as the taxa considered as exclusive, does not support the validity of the biozones of Trigodon gaudryi and Neocavia depressidens previously proposed. On this basis, a new scheme for the Monte Hermoso Formation at its type locality is proposed, including a new single biostratigraphic unit. This unit is the Eumysops laeviplicatus Range Zone, which represents the biostratigraphic base for the Montehermosan Stage/Age of the early Pliocene.

Genetic Interaction of Neuroglian and Semaphorin1a during Guidance and Synapse Formation

PubMed Central

Godenschwege, Tanja A.; Murphey, Rodney K.

2009-01-01

We have previously demonstrated a function for Neuroglian and Semaphorin1a in Drosophila giant fiber circuit formation. Both molecules are required for guiding the giant fibers out of the brain and have distinct functions during giant synapse formation. In this study we characterized the effects of various combinations of Neuroglian and Semaphorin1a gain and loss of function backgrounds on giant fiber circuitry formation. We found that Neuroglian and Semaphorin1a genetically interact with each other during axon guidance as well as during synapse formation. Our experiments revealed that during pathfinding of the giant fibers out of the brain, Neuroglian function seems to be dependent on Semaphorin1a. In contrast, during giant fiber synapse formation we observed that Semaphorin1a signaling as a receptor can be altered by Neuroglian in the same cell. In summary, our findings suggest that Neuroglian and Semaphorin1a can regulate each other’s function in cis and that the resultant signaling output is possibly different during guidance and synapse formation. PMID:19052954

LBGs properties from z˜3 to z˜6

NASA Astrophysics Data System (ADS)

de Barros, S.; Schaerer, D.; Stark, D. P.

2011-12-01

We analyse the spectral energy distribution (SED) of U, B, V and i-dropout samples from GOODS-MUSIC and we determine their physical properties, such as stellar age and mass, dust attenuation and star formation rate (SFR). Furthermore, we examine how the strength of Lyα emission can be constrained from broad-band SED fits instead of relying in spectroscopy. We use our SED fitting tool including the effects of nebular emission and we explore different star formation histories (SFHs). We find that SEDs are statistically better fitted with nebular emission and exponentially decreasing star formation. Considering this result, stellar mass and star formation rate (SFR) estimations modify the specific SFR (SFR/M_{⋆}) - redshift relation, in compared to previous studies. Finally, our inferred Lyα properties are in good agreement with the available spectroscopic observations.

Stratigraphy and vertical hydraulic conductivity of the St. Francois Confining Unit in the Viburnum Trend and evaluation of the Unit in the Viburnum Trend and exploration areas, southeastern Missouri

USGS Publications Warehouse

Kleeschulte, Michael J.; Seeger, Cheryl M.

2003-01-01

The confining ability of the St. Francois confining unit (Derby-Doerun Dolomite and Davis Formation) was evaluated in ten townships (T. 31?35 N. and R. 01?02 W.) along the Viburnum Trend of southeastern Missouri. Vertical hydraulic conductivity data were compared to similar data collected during two previous studies 20 miles south of the Viburnum Trend, in two lead-zinc exploration areas that may be a southern extension of the Viburnum Trend. The surficial Ozark aquifer is the primary source of water for domestic and public-water supplies and major springs in southern Missouri. The St. Francois confining unit lies beneath the Ozark aquifer and impedes the movement of water between the Ozark aquifer and the underlying St. Francois aquifer (composed of the Bonneterre Formation and Lamotte Sandstone). The Bonneterre Formation is the primary host formation for lead-zinc ore deposits of the Viburnum Trend and potential host formation in the exploration areas. For most of the more than 40 years the mines have been in operation along the Viburnum Trend, about 27 million gallons per day were being pumped from the St. Francois aquifer for mine dewatering. Previous studies conducted along the Viburnum Trend have concluded that no large cones of depression have developed in the potentiometric surface of the Ozark aquifer as a result of mining activity. Because of similar geology, stratigraphy, and depositional environment between the Viburnum Trend and the exploration areas, the Viburnum Trend may be used as a pertinent, full-scale model to study and assess how mining may affect the exploration areas. Along the Viburnum Trend, the St. Francois confining unit is a complex series of dolostones, limestones, and shales that generally is 230 to 280 feet thick with a net shale thickness ranging from less than 25 to greater than 100 feet with the thickness increasing toward the west. Vertical hydraulic conductivity values determined from laboratory permeability tests were used to represent the St. Francois confining unit along the Viburnum Trend. The Derby-Doerun Dolomite and Davis Formation are statistically similar, but the Davis Formation would be the more hydraulically restrictive medium. The shale and carbonate values were statistically different. The median vertical hydraulic conductivity value for the shale samples was 62 times less than the carbonate samples. Consequently, the net shale thickness of the confining unit along the Viburnum Trend significantly affects the effective vertical hydraulic conductivity. As the percent of shale increases in a given horizon, the vertical hydraulic conductivity decreases. The range of effective vertical hydraulic conductivity for the confining unit in the Viburnum Trend was estimated to be a minimum of 2 x 10-13 ft/s (foot per second) and a maximum of 3 x 10-12 ft/s. These vertical hydraulic conductivity values are considered small and verify conclusions of previous studies that the confining unit effectively impedes the flow of ground water between the Ozark aquifer and the St. Francois aquifer along the Viburnum Trend. Previously-collected vertical hydraulic conductivity data for the two exploration areas from two earlier studies were combined with the data collected along the Viburnum Trend. The nonparametric Kruskal-Wallis statistical test shows the vertical hydraulic conductivity of the St. Francois confining unit along the Viburnum Trend, and west and east exploration areas are statistically different. The vertical hydraulic conductivity values generally are the largest in the Viburnum Trend and are smallest in the west exploration area. The statistical differences in these values do not appear to be attributed strictly to either the Derby-Doerun Dolomite or Davis Formation, but instead they are caused by the differences in the carbonate vertical hydraulic conductivity values at the three locations. The calculated effective vertical hydraulic conductivity range for the St. Franc

From Cosmic Dusk till Dawn with RELICS

NASA Astrophysics Data System (ADS)

Bradac, Marusa

When did galaxies start forming stars? What is the role of distant galaxies in galaxy formation models and the epoch of reionization? What are the conditions in typical lowmass, star-forming galaxies at z 4? Why is galaxy evolution dependent on environment? Recent observations indicate several critical puzzles in studies that address these questions. Chief among these, galaxies might have started forming stars earlier than previously thought (<400Myr after the Big Bang) and their star formation history differs from what is predicted from simulations. Furthermore, the details of the mechanisms that regulate star formation and morphological transformation in dense environments are still unknown. To solve these puzzles of galaxy evolution, we will use 41 galaxy clusters from the RELICS program (Reionization Lensing Cluster Survey) that are among the most powerful cosmic telescopes. Their magnification will allow us to study stellar properties of a large number of galaxies all the way to the reionization era. Accurate knowledge of stellar masses, ages, and star formation rates (SFRs) requires measuring both rest-frame UV and optical light, which only Spitzer can probe at z>0.5-11 for a sufficiently large sample of typical galaxies. This program will combine Spitzer imaging from two large programs, Director Discretionary Time (DDT) and the SRELICS program led by the PI.The main challenge in a study such as this is the capability to perform reliable photometry in crowded fields. Our team recently helped develop TPHOT, which is a much improved and much faster version of previously available codes. TPHOT is specifically designed to extract fluxes in crowded fields with very different PSFs. We will combine Spitzer photometry with ground based imaging and spectroscopy to obtain robust measurements of galaxy star formation rates, stellar masses, and stellar ages. This program will be a crucial legacy complement to previous Spitzer/IRAC deep blank field surveys and cluster studies, and will open up new parameter space by probing intrinsically fainter objects than most current surveys with a significantly improved sample variance over deep field surveys. It will allow us to study the properties (e.g. SFRs and stellar masses) of a large number of galaxies (200 at z=6-10), thus meeting our goal of reconstructing the cosmic SFR density with sufficient precision to better understand the role of galaxies in the reionization process. We will measure the presence (or absence) of established stellar populations with Spitzer for the largest sample to date. Furthermore this proposal will allow us to study the SFRs of the intrinsically faint (and magnified) intermediate redshift (z 4) galaxies, as well as the stellar mass function of z=0.3-0.7 galaxy members of our cluster sample, thereby expanding our understanding of star formation from reionization to the epoch of galaxy formation and dense environments. Many of the science goals of this proposal are main science drivers for JWST. Due to magnification our effective depth and resolution match those of the JWST blank fields and affords us a sneak preview of JWST sources with Spitzer now. This program will thus provide a valuable test-bed for simulations, observation planning and source selection just in time for JWST Cycle 1.

THE ROLE OF GAS-PHASE CL2 IN THE FORMATION OF PCDD/PCDF DURING WASTE COMBUSTION

EPA Science Inventory

Results of previous experiments investigating formation of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/PCDF) through low-temperature (300°C), fly-ash-catalyzed reactions are demonstrated to have occurred through intermediate formation of gas-phase Cl₂ by deco...

Correlation, sedimentology, structural setting, chemical composition, and provenance of selected formations in Mesoproterozoic Lemhi Group, central Idaho

USGS Publications Warehouse

Tysdal, Russell G.; Lindsey, David A.; Taggart, Joseph E.

2003-01-01

A unit of the Mesoproterozoic Apple Creek Formation of the Lemhi Range previously was correlated with part of the lower subunit of the Mesoproterozoic Yellowjacket Formation in the Salmon River Mountains. Strata currently assigned to the middle subunit of the Yellowjacket Formation lie conformably above the Apple Creek unit in the Salmon River Mountains, and are here renamed the banded siltite unit and reassigned to the Apple Creek Formation. Almost all of the banded siltite unit is preserved within the Salmon River Mountains, where it grades upward into clastic rocks that currently are assigned to the upper subunit of the Yellowjacket Formation and that here are reassigned to the Gunsight Formation. The banded siltite unit of the Apple Creek Formation is composed of a turbidite sequence, as recognized by previous workers. Uppermost strata of the unit were reworked by currents, possibly storm generated, and adjusted to a high water content by developing abundant soft-sediment deformation features. Basal strata of the overlying Gunsight Formation in the Salmon River Mountains display abundant hummocky crossbeds, storm-generated features deposited below fair-weather wave base, that are conformable above the storm-reworked deposits. The hummocky crossbedded strata grade upward into marine shoreface strata deposited above fair-weather wave base, which in turn are succeeded by fluvial strata. Hummocky and shoreface strata are absent from the Gunsight Formation in the Lemhi Range. The major thickness of the Gunsight Formation in both the Salmon River Mountains and the Lemhi Range is composed of fluvial rocks, transitional in the upper part into marine rocks of the Swauger Formation. The fluvial strata are mainly characterized by stacked sheets of metasandstone and coarse siltite; they are interpreted as deposits of braided rivers. The Poison Creek thrust fault of the Lemhi Range extends northwestward through the study area in the east-central part of the Salmon River Mountains. The Apple Creek and Gunsight Formations on the southwest side of the thrust fault were transported to the northeast as part of the Poison Creek thrust sheet. A segment of the thrust fault within the Gunsight Formation in the Salmon River Mountains subsequently underwent normal displacement. Along this segment, lower Gunsight strata on the southwest were juxtaposed against upper Gunsight and Swauger strata on the northeast.

The Effect of Cryopreserved Human Placental Tissues on Biofilm Formation of Wound-Associated Pathogens.

PubMed

Mao, Yong; Singh-Varma, Anya; Hoffman, Tyler; Dhall, Sandeep; Danilkovitch, Alla; Kohn, Joachim

2018-01-08

Biofilm, a community of bacteria, is tolerant to antimicrobial agents and ubiquitous in chronic wounds. In a chronic DFU (Diabetic Foot Ulcers) clinical trial, the use of a human cryopreserved viable amniotic membrane (CVAM) resulted in a high rate of wound closure and reduction of wound-related infections. Our previous study demonstrated that CVAM possesses intrinsic antimicrobial activity against a spectrum of wound-associated bacteria under planktonic culture conditions. In this study, we evaluated the effect of CVAM and cryopreserved viable umbilical tissue (CVUT) on biofilm formation of S. aureus and P. aeruginosa , the two most prominent pathogens associated with chronic wounds. Firstly, we showed that, like CVAM, CVUT released antibacterial activity against multiple bacterial pathogens and the devitalization of CVUT reduced its antibacterial activity. The biofilm formation was then measured using a high throughput method and an ex vivo porcine dermal tissue model. We demonstrate that the formation of biofilm was significantly reduced in the presence of CVAM- or CVUT-derived conditioned media compared to control assay medium. The formation of P. aeruginosa biofilm on CVAM-conditioned medium saturated porcine dermal tissues was reduced 97% compared with the biofilm formation on the control medium saturated dermal tissues. The formation of S. auerus biofilm on CVUT-conditioned medium saturated dermal tissues was reduced 72% compared with the biofilm formation on the control tissues. This study is the first to show that human cryopreserved viable placental tissues release factors that inhibit biofilm formation. Our results provide an explanation for the in vivo observation of their ability to support wound healing.

Land use planning and surface heat island formation: A parcel-based radiation flux approach

NASA Astrophysics Data System (ADS)

Stone, Brian; Norman, John M.

This article presents a study of residential parcel design and surface heat island formation in a major metropolitan region of the southeastern United States. Through the integration of high-resolution multispectral data (10 m) with property tax records for over 100,000 single-family residential parcels in the Atlanta, Georgia, metropolitan region, the influence of the size and material composition of residential land use on an indicator of surface heat island formation is reported. In contrast to previous work on the urban heat island, this study derives a parcel-based indicator of surface warming to permit the impact of land use planning regulations governing the density and design of development on the excess surface flux of heat energy to be measured. The results of this study suggest that the contribution of individual land parcels to regional surface heat island formation could be reduced by approximately 40% through the adoption of specific land use planning policies, such as zoning and subdivision regulations, and with no modifications to the size or albedo of the residential structure.

The herpes simplex virus 2 virion-associated ribonuclease vhs interferes with stress granule formation.

PubMed

Finnen, Renée L; Hay, Thomas J M; Dauber, Bianca; Smiley, James R; Banfield, Bruce W

2014-11-01

In a previous study, it was observed that cells infected with herpes simplex virus 2 (HSV-2) failed to accumulate stress granules (SGs) in response to oxidative stress induced by arsenite treatment. As a follow-up to this observation, we demonstrate here that disruption of arsenite-induced SG formation by HSV-2 is mediated by a virion component. Through studies on SG formation in cells infected with HSV-2 strains carrying defective forms of UL41, the gene that encodes vhs, we identify vhs as a virion component required for this disruption. Cells infected with HSV-2 strains producing defective forms of vhs form SGs spontaneously late in infection. In addition to core SG components, these spontaneous SGs contain the viral immediate early protein ICP27 as well as the viral serine/threonine kinase Us3. As part of these studies, we reexamined the frameshift mutation known to reside within the UL41 gene of HSV-2 strain HG52. We demonstrate that this mutation is unstable and can rapidly revert to restore wild-type UL41 following low-multiplicity passaging. Identification of the involvement of virion-associated vhs in the disruption of SG formation will enable mechanistic studies on how HSV-2 is able to counteract antiviral stress responses early in infection. In addition, the ability of Us3 to localize to stress granules may indicate novel roles for this viral kinase in the regulation of translation. Eukaryotic cells respond to stress by rapidly shutting down protein synthesis and storing mRNAs in cytoplasmic stress granules (SGs). Stoppages in protein synthesis are problematic for all viruses as they rely on host cell machinery to synthesize viral proteins. Thus, many viruses target SGs for disruption or modification. Infection by herpes simplex virus 2 (HSV-2) was previously observed to disrupt SG formation induced by oxidative stress. In this follow-up study, we identify virion host shutoff protein (vhs) as a viral protein involved in this disruption. The identification of a specific viral protein involved in disrupting SG formation is a key step toward understanding how HSV-2 interacts with these antiviral structures. Additionally, this understanding may provide insights into the biology of SGs that may find application in studies on human motor neuron degenerative diseases, like amyotrophic lateral sclerosis (ALS), which may arise as a result of dysregulation of SG formation. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Identification of 4-(3-Pyridyl)-4-oxobutyl-2'-deoxycytidine Adducts Formed in the Reaction of DNA with 4-(Acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone: A Chemically Activated Form of Tobacco-Specific Carcinogens.

PubMed

Michel, Anna K; Zarth, Adam T; Upadhyaya, Pramod; Hecht, Stephen S

2017-03-31

Metabolic activation of the carcinogenic tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK, 1 ) and N '-nitrosonornicotine (NNN, 2 ) results in the formation of 4-(3-pyridyl)-4-oxobutyl (POB)-DNA adducts, several of which have been previously identified both in vitro and in tissues of laboratory animals treated with NNK or NNN. However, 2'-deoxycytidine adducts formed in this process have been incompletely examined in previous studies. Therefore, in this study we prepared characterized standards for the identification of previously unknown 2'-deoxycytidine and 2'-deoxyuridine adducts that could be produced in these reactions. The formation of these products in reactions of 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNKOAc, 3 ), a model 4-(3-pyridyl)-4-oxobutylating agent, with DNA was investigated. The major 2'-deoxycytidine adduct, identified as its stable cytosine analogue O 2 -[4-(3-pyridyl)-4-oxobut-1-yl]-cytosine ( 12 ), was O 2 -[4-(3-pyridyl)-4-oxobut-1-yl]-2'-deoxycytidine ( 13 ), whereas lesser amounts of 3-[4-(3-pyridyl)-4-oxobut-1-yl]-2'-deoxycytidine ( 14 ) and N 4 -[4-(3-pyridyl)-4-oxobut-1-yl]-2'-deoxycytidine ( 15 ) were also observed. The potential conversion of relatively unstable 2'-deoxycytidine adducts to stable 2'-deoxyuridine adducts by treatment of the adducted DNA with bisulfite was also investigated, but the harsh conditions associated with this approach prevented quantitation. The results of this study provide new validated standards for the study of 4-(3-pyridyl)-4-oxobutylation of DNA, a critical reaction in the carcinogenesis by 1 and 2 , and demonstrate the presence of previously unidentified 2'-deoxycytidine adducts in this DNA.

Facile Formation of Acetic Sulfuric Anhydride in a Supersonic Jet: Characterization by Microwave Spectroscopy and Computational Chemistry

NASA Astrophysics Data System (ADS)

Huff, Anna; Smith, CJ; Mackenzie, Becca; Leopold, Ken

2017-06-01

Sulfur trioxide and acetic acid are shown to react under supersonic jet conditions to form acetic sulfuric anhydride, CH_{3}COOSO_{2}OH. Rotational spectra of the parent, ^{34}S, methyl ^{13}C, and fully deuterated isotopologues have been observed by chirped-pulse and conventional cavity microwave spectroscopy. A and E internal rotation states have been observed for each isotopologue studied and the methyl group internal rotation barriers have been determined (241.043(65) \\wn for the parent species). The reaction is analogous to that of our previous report on the reaction of sulfur trioxide and formic acid. DFT and CCSD calculations are also presented which indicate that the reaction proceeds via a π_{2} + π_{2} + σ_{2} cycloaddition reaction. These results support our previous conjecture that the reaction of SO_{3} with carboxylic acids is both facile and general. Possible implications for atmospheric aerosol formation are discussed.

Health Professionals Prefer to Communicate Risk-Related Numerical Information Using "1-in-X" Ratios.

PubMed

Sirota, Miroslav; Juanchich, Marie; Petrova, Dafina; Garcia-Retamero, Rocio; Walasek, Lukasz; Bhatia, Sudeep

2018-04-01

Previous research has shown that format effects, such as the "1-in-X" effect-whereby "1-in-X" ratios lead to a higher perceived probability than "N-in-N*X" ratios-alter perceptions of medical probabilities. We do not know, however, how prevalent this effect is in practice; i.e., how often health professionals use the "1-in-X" ratio. We assembled 4 different sources of evidence, involving experimental work and corpus studies, to examine the use of "1-in-X" and other numerical formats quantifying probability. Our results revealed that the use of the "1-in-X" ratio is prevalent and that health professionals prefer this format compared with other numerical formats (i.e., the "N-in-N*X", %, and decimal formats). In Study 1, UK family physicians preferred to communicate prenatal risk using a "1-in-X" ratio (80.4%, n = 131) across different risk levels and regardless of patients' numeracy levels. In Study 2, a sample from the UK adult population ( n = 203) reported that most GPs (60.6%) preferred to use "1-in-X" ratios compared with other formats. In Study 3, "1-in-X" ratios were the most commonly used format in a set of randomly sampled drug leaflets describing the risk of side effects (100%, n = 94). In Study 4, the "1-in-X" format was the most commonly used numerical expression of medical probabilities or frequencies on the UK's NHS website (45.7%, n = 2,469 sentences). The prevalent use of "1-in-X" ratios magnifies the chances of increased subjective probability. Further research should establish clinical significance of the "1-in-X" effect.

Phonological Advance Planning in Sentence Production

ERIC Educational Resources Information Center

Oppermann, Frank; Jescheniak, Jorg D.; Schriefers, Herbert

2010-01-01

Our study addresses the scope of phonological advance planning during sentence production using a novel experimental procedure. The production of German sentences in various syntactic formats (SVO, SOV, and VSO) was cued by presenting pictures of the agents of previously memorized agent-action-patient scenes. To tap the phonological activation of…

Evolution: oskar reveals missing link in co-optive evolution.

PubMed

Abouheif, Ehab

2013-01-07

The oskar gene is critical for germ plasm formation and reproduction in higher insects. A recent study reports that oskar has more ancient roots than previously thought, indicating it was co-opted for its reproductive role in higher insects. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of Referent Token Variability on L2 Vocabulary Learning

ERIC Educational Resources Information Center

Sommers, Mitchell S.; Barcroft, Joe

2013-01-01

Previous research has demonstrated substantially improved second language (L2) vocabulary learning when spoken word forms are varied using multiple talkers, speaking styles, or speaking rates. In contrast, the present study varied visual representations of referents for target vocabulary. English speakers learned Spanish words in formats of no…

RNAi screen of DAF-16/FOXO target genes in C. elegans links pathogenesis and dauer formation.

PubMed

Jensen, Victor L; Simonsen, Karina T; Lee, Yu-Hui; Park, Donha; Riddle, Donald L

2010-12-31

The DAF-16/FOXO transcription factor is the major downstream output of the insulin/IGF1R signaling pathway controlling C. elegans dauer larva development and aging. To identify novel downstream genes affecting dauer formation, we used RNAi to screen candidate genes previously identified to be regulated by DAF-16. We used a sensitized genetic background [eri-1(mg366); sdf-9(m708)], which enhances both RNAi efficiency and constitutive dauer formation (Daf-c). Among 513 RNAi clones screened, 21 displayed a synthetic Daf-c (SynDaf) phenotype with sdf-9. One of these genes, srh-100, was previously identified to be SynDaf, but twenty have not previously been associated with dauer formation. Two of the latter genes, lys-1 and cpr-1, are known to participate in innate immunity and six more are predicted to do so, suggesting that the immune response may contribute to the dauer decision. Indeed, we show that two of these genes, lys-1 and clc-1, are required for normal resistance to Staphylococcus aureus. clc-1 is predicted to function in epithelial cohesion. Dauer formation exhibited by daf-8(m85), sdf-9(m708), and the wild-type N2 (at 27°C) were all enhanced by exposure to pathogenic bacteria, while not enhanced in a daf-22(m130) background. We conclude that knockdown of the genes required for proper pathogen resistance increases pathogenic infection, leading to increased dauer formation in our screen. We propose that dauer larva formation is a behavioral response to pathogens mediated by increased dauer pheromone production.

Microbial community structure in three deep-sea carbonate crusts.

PubMed

Heijs, S K; Aloisi, G; Bouloubassi, I; Pancost, R D; Pierre, C; Sinninghe Damsté, J S; Gottschal, J C; van Elsas, J D; Forney, L J

2006-10-01

Carbonate crusts in marine environments can act as sinks for carbon dioxide. Therefore, understanding carbonate crust formation could be important for understanding global warming. In the present study, the microbial communities of three carbonate crust samples from deep-sea mud volcanoes in the eastern Mediterranean were characterized by sequencing 16S ribosomal RNA (rRNA) genes amplified from DNA directly retrieved from the samples. In combination with the mineralogical composition of the crusts and lipid analyses, sequence data were used to assess the possible role of prokaryotes in crust formation. Collectively, the obtained data showed the presence of highly diverse communities, which were distinct in each of the carbonate crusts studied. Bacterial 16S rRNA gene sequences were found in all crusts and the majority was classified as alpha-, gamma-, and delta- Proteobacteria. Interestingly, sequences of Proteobacteria related to Halomonas and Halovibrio sp., which can play an active role in carbonate mineral formation, were present in all crusts. Archaeal 16S rRNA gene sequences were retrieved from two of the crusts studied. Several of those were closely related to archaeal sequences of organisms that have previously been linked to the anaerobic oxidation of methane (AOM). However, the majority of archaeal sequences were not related to sequences of organisms known to be involved in AOM. In combination with the strongly negative delta 13C values of archaeal lipids, these results open the possibility that organisms with a role in AOM may be more diverse within the Archaea than previously suggested. Different communities found in the crusts could carry out similar processes that might play a role in carbonate crust formation.

The Formation of the South Korean Identity through National Curriculum in the South Korean Historical Context: Conflicts and Challenges

ERIC Educational Resources Information Center

So, Kyunghee; Kim, Jungyun; Lee, Sunyoung

2012-01-01

This study explores how the South Korean identity has been formed and transformed by examining the Korean national curriculum in its historical context. The study first examines how the Korean identity, previously formed by traditional ethnic values, has been transformed during the period of national modernization. It then describes the efforts to…

Effects of Aging on True and False Memory Formation: An fMRI Study

ERIC Educational Resources Information Center

Dennis, Nancy A.; Kim, Hongkeun; Cabeza, Roberto

2007-01-01

Compared to young, older adults are more likely to forget events that occurred in the past as well as remember events that never happened. Previous studies examining false memories and aging have shown that these memories are more likely to occur when new items share perceptual or semantic similarities with those presented during encoding. It is…

Attainment of Selected Earth Science Concepts by Texas High School Seniors.

ERIC Educational Resources Information Center

Rollins, Mavis M.; And Others

The purpose of this study was to determine whether high school seniors (N=492) had attained each of five selected earth science concepts and if said attainment was influenced by the number of science courses completed. A 72-item, multiple-choice format test (12 items for each concept) was developed and piloted previous to this study to measure…

[[superscript 3]H]-Flunitrazepam-Labeled Benzodiazepine Binding Sites in the Hippocampal Formation in Autism: A Multiple Concentration Autoradiographic Study

ERIC Educational Resources Information Center

Guptill, Jeffrey T.; Booker, Anne B.; Gibbs, Terrell T.; Kemper, Thomas L.; Bauman, Margaret L.; Blatt, Gene J.

2007-01-01

Increasing evidence indicates that the GABAergic system in cerebellar and limbic structures is affected in autism. We extended our previous study that found reduced [[superscript 3]H] flunitrazepam-labeled benzodiazepine sites in the autistic hippocampus to determine whether this reduction was due to a decrease in binding site number (B [subscript…

SGK Protein Kinase Facilitates the Expression of Long-Term Potentiation in Hippocampal Neurons

ERIC Educational Resources Information Center

Ma, Yun L.; Tsai, Ming C.; Hsu, Wei L.; Lee, Eminy H.Y.

2006-01-01

Previous studies showed that the serum- and glucocorticoid-inducible kinase ("sgk") gene plays an important role in long-term memory formation. The present study further examined the role of SGK in long-term potentiation (LTP). The dominant-negative mutant of "sgk," SGKS422A, was used to inactivate SGK. Results revealed a time-dependent increase…

The Nature of Elementary Science Teachers' Experiences with Synchronous Online, Asynchronous Online and Face-to-Face Coaching

NASA Astrophysics Data System (ADS)

Gilbert, Amanda M.

This study investigated the nature of instructional coaching interactions in three formats: online synchronous, online asynchronous, and face-to-face. Knight's (2007) Seven Partnership Principles of Instructional Coaching were used as a framework to analyze and compare the coaching interactions between coach and teacher to determine whether online coaching may be a viable option to provide support for the teachers unprepared to teach the new science standards. Some previous research has suggested that online communication can result in deeper personal interactions (Walther, 1996), while other studies suggest that interactions are more natural and easier in formats that are more similar to face-to-face interactions (Kock, 2005). The findings of this study support the media naturalness theory (Kock, 2005) and suggest that collaboration may be especially difficult in asynchronous online communication. Although differences were noted in the actual interactions, teacher perception remained fairly consistently positive across the three formats. Research beyond this exploratory study is needed to make findings generalizable.

New evidence for late mesozoic-early Cenozoic evolution of the Chilean Andes in the upper Tinguiririca valley (35 °S), central Chile

NASA Astrophysics Data System (ADS)

Charrier, Reynaldo; Wyss, AndréR.; Flynn, John J.; Swisher, Carl C.; Norell, Mark A.; Zapatta, Franyo; McKenna, Malcolm C.; Novacek, Michael J.

1996-11-01

New geologic, paleontologic and isotopic geochronometric results from the Termas del Flaco region in the upper Tinguiririca River valley in central Chile demand considerable revision of the accepted geotectonic history of the Andean Main Range in this region. A diverse, transitional Eocene-Oligocene aged, land-mammal fauna was recovered from several sites in volcaniclastic sediments of the Coya-Machalí (=Abanico) Formation. Major results of our study include: 1) The 1000 + m thick studied deposits, previously attributed to the Cretaceous Colimapu Formation, belong to the Coya-Machalí (=Abanico) Formation. Radioisotopic data from levels immediately above (31.5 Ma) and below (37.S Ma) the fossiliferous horizon indicate a latest Eocene to early Oligocene age for the basal part of the formation and the fauna contained in it. 2) The fossiliferous unit rests with slight angular offset on different Mesozoic units: "Brownish-red Clastic Unit" (BRCU) and Baños del Flaco Formation; in a limited area it also overlies a white tuff dated at 104 Ma. 3) The contacts just discussed (none of which is attributable to faulting), demonstrate the existence of two, or possibly three, unconformities in the region. 4) Sedimentological criteria argue against reference of the BRCU to the Colimapu Formation, and imply correlation of the former unit to basal levels with in the late Cretaceous Neuquén Group of western Argentina. 5) The Coya-Machalí Formation, previously viewed as representing the western volcanic equivalent of Riográndico Supercycle deposits of western Argentino, is likely coeval to much younger units in that region such as the Agua de la Piedra Formation. 6) Paleomagnetic results from the fossil producing horizon indicate about 20 ° of post-early Oligocene, counterclockwise rotation. 7) Fossil mammals from the Coya-Machalí Formation near Termas del Flaco represent a distinct biochronologic interval not heretofore clearly recognized from elsewhere on the continent. This new fauna helps fill the long recognized post-?middle Eocene, pre-late Oligocene faunal hiatus between the Mustersan and Deseadan South American Land Mammal Ages (SALMA). In addition, it records the earliest known presence of rodents in South America and otherwise differs strongly from the enigmatic Divisaderan SALMA.

Genes involved in Listeria monocytogenes biofilm formation at a simulated food processing plant temperature of 15 °C.

PubMed

Piercey, Marta J; Hingston, Patricia A; Truelstrup Hansen, Lisbeth

2016-04-16

Listeria monocytogenes is a pathogenic foodborne bacterium whose persistence in food processing environments is in part attributed to its biofilm formation. Most biofilm studies have been carried out at 30-37 °C rather than at temperatures found in the food processing plants (i.e., 10-20 °C). The objective of the present study was to mine for novel genes that contribute to L. monocytogenes biofilm formation at 15 °C using the random insertional mutagenesis approach. A library of 11,024 L. monocytogenes 568 (serotype 1/2a) Himar1 insertional mutants was created. Mutants with reduced or enhanced biofilm formation at 15 °C were detected in microtiter plate assays with crystal violet and safranin staining. Fourteen mutants expressed enhanced biofilm phenotypes, and harbored transposon insertions in genes encoding cell wall biosynthesis, motility, metabolism, stress response, and cell surface associated proteins. Deficient mutants (n=5) contained interruptions in genes related to peptidoglycan, teichoic acid, or lipoproteins. Enhanced mutants produced significantly (p<0.05) higher cell densities in biofilm formed on stainless steel (SS) coupons at 15 °C (48 h) than deficient mutants, which were also more sensitive to benzalkonium chloride. All biofilm deficient mutants and four enhanced mutants in the microtiter plate assay (flaA, cheR, lmo2563 and lmo2488) formed no biofilm in a peg lid assay (Calgary biofilm device) while insertions in lmo1224 and lmo0543 led to excess biofilm in all assays. Two enhanced biofilm formers were more resistant to enzymatic removal with DNase, proteinase K or pectinase than the parent strain. Scanning electron microscopy of individual biofilms made by five mutants and the parent on SS surfaces showed formation of heterogeneous biofilm with dense zones by immotile mutants, while deficient mutants exhibited sparse growth. In conclusion, interruptions of 9 genes not previously linked to biofilm formation in L. monocytogenes (lmo2572, lmo2488 (uvrA), lmo1224, lmo0434 (inlB), lmo0263 (inlH), lmo0543, lmo0057 (EsaA), lmo2563, lmo0453), caused enhanced biofilm formation in the bacterium at 15 °C. The remaining mutants harbored interruptions in 10 genetic loci previously associated with biofilm formation at higher temperatures, indicating some temperature driven differences in the formation of biofilm by L. monocytogenes. Copyright © 2016 Elsevier B.V. All rights reserved.

The Collins Creek and Pleasant Creek Formations: Two new upper cretaceous subsurface units in the Carolina/Georgia Coastal Plain

USGS Publications Warehouse

,; Prowell, D.C.; Christopher, R.A.

2004-01-01

This paper formally defines two new Upper Cretaceous subsurface units in the southern Atlantic Coastal Plain of North Carolina, South Carolina and Georgia: the Collins Creek Formation and the Pleasant Creek Formation. These units are confined to the subsurface of the outer Coastal Plain, and their type sections are established in corehole CHN-820 from Charleston County, S.C. The Collins Creek Formation consists of greenish-gray lignitic sand and dark-greenish-gray sandy clay and is documented in cores from Allendale, Beaufort, Berkeley, Dorchester, Jasper and Marion Counties, South Carolina, and from Screven County, Georgia. Previously, Collins Creek strata had been incorrectly assigned to the Middendorf Formation. These sediments occupy a stratigraphic position between the Turonian/Coniacian Cape Fear Formation (?) below and the proposed upper Coniacian to middle Santonian Pleasant Creek Formation above. The Collins Creek Formation is middle and late Coniacian in age on the basis of calcareous nannofossil and palynomorph analyses. The Pleasant Creek Formation consists of olive-gray sand and dark-greenish-gray silty to sandy clay and is documented in cores from New Hanover County, North Carolina, and Berkeley, Charleston, Dorchester, Horry and Marion Counties, South Carolina. The strata of this unit previously were assigned incorrectly to the Middendorf Formation and (or) the Cape Fear Formation. These sediments occupy a stratigraphic position between the proposed Collins Creek Formation below and the Shepherd Grove Formation above. The Pleasant Creek Formation is late Coniacian and middle Santonian in age, on the basis of its calcareous nannofossil and palynomorph assemblages.

Assessing the Formation of Experience-Based Gender Expectations in an Implicit Learning Scenario

PubMed Central

Öttl, Anton; Behne, Dawn M.

2017-01-01

The present study investigates the formation of new word-referent associations in an implicit learning scenario, using a gender-coded artificial language with spoken words and visual referents. Previous research has shown that when participants are explicitly instructed about the gender-coding system underlying an artificial lexicon, they monitor the frequency of exposure to male vs. female referents within this lexicon, and subsequently use this probabilistic information to predict the gender of an upcoming referent. In an explicit learning scenario, the auditory and visual gender cues are necessarily highlighted prior to acqusition, and the effects previously observed may therefore depend on participants' overt awareness of these cues. To assess whether the formation of experience-based expectations is dependent on explicit awareness of the underlying coding system, we present data from an experiment in which gender-coding was acquired implicitly, thereby reducing the likelihood that visual and auditory gender cues are used strategically during acquisition. Results show that even if the gender coding system was not perfectly mastered (as reflected in the number of gender coding errors), participants develop frequency based expectations comparable to those previously observed in an explicit learning scenario. In line with previous findings, participants are quicker at recognizing a referent whose gender is consistent with an induced expectation than one whose gender is inconsistent with an induced expectation. At the same time however, eyetracking data suggest that these expectations may surface earlier in an implicit learning scenario. These findings suggest that experience-based expectations are robust against manner of acquisition, and contribute to understanding why similar expectations observed in the activation of stereotypes during the processing of natural language stimuli are difficult or impossible to suppress. PMID:28936186

Secondary organic aerosol formation from photochemical aging of light-duty gasoline vehicle exhausts in a smog chamber

NASA Astrophysics Data System (ADS)

Liu, T.; Wang, X.; Deng, W.; Hu, Q.; Ding, X.; Zhang, Y.; He, Q.; Zhang, Z.; Lü, S.; Bi, X.; Chen, J.; Yu, J.

2015-04-01

In China, fast increase in passenger vehicles has procured the growing concern about vehicle exhausts as an important source of anthropogenic secondary organic aerosols (SOA) in megacities hard-hit by haze. However, there are still no chamber simulation studies in China on SOA formation from vehicle exhausts. In this study, the SOA formation of emissions from two idling light-duty gasoline vehicles (LDGVs) (Euro 1 and Euro 4) in China was investigated in a 30 m3 smog chamber. Five photo-oxidation experiments were carried out at 25 °C with the relative humidity around 50%. After aging at an OH exposure of 5 × 106 molecules cm-3 h, the formed SOA was 12-259 times as high as primary OA (POA). The SOA production factors (PF) were 0.001-0.044 g kg-1 fuel, comparable with those from the previous studies at the quite similar OH exposure. This quite lower OH exposure than that in typical atmospheric condition might however lead to the underestimation of the SOA formation potential from LDGVs. Effective SOA yield data in this study were well fit by a one-product gas-particle partitioning model and quite lower than those of a previous study investigating SOA formation form three idling passenger vehicles (Euro 2-Euro 4). Traditional single-ring aromatic precursors and naphthalene could explain 51-90% of the formed SOA. Unspeciated species such as branched and cyclic alkanes might be the possible precursors for the unexplained SOA. A high-resolution time-of-flight aerosol mass spectrometer was used to characterize the chemical composition of SOA. The relationship between f43 (ratio of m/z 43, mostly C2H3O+, to the total signal in mass spectrum) and f44 (mostly CO2+) of the gasoline vehicle exhaust SOA is similar to the ambient semi-volatile oxygenated organic aerosol (SV-OOA). We plot the O : C and H : C molar ratios of SOA in a Van Krevelen diagram. The slopes of ΔH : C/ΔO : C ranged from -0.59 to -0.36, suggesting that the oxidation chemistry in these experiments was a combination of carboxylic acid and alcohol/peroxide formation.

Baseline metal enrichment from Population III star formation in cosmological volume simulations

NASA Astrophysics Data System (ADS)

Jaacks, Jason; Thompson, Robert; Finkelstein, Steven L.; Bromm, Volker

2018-04-01

We utilize the hydrodynamic and N-body code GIZMO coupled with our newly developed sub-grid Population III (Pop III) Legacy model, designed specifically for cosmological volume simulations, to study the baseline metal enrichment from Pop III star formation at z > 7. In this idealized numerical experiment, we only consider Pop III star formation. We find that our model Pop III star formation rate density (SFRD), which peaks at ˜ 10- 3 M⊙ yr- 1 Mpc- 1 near z ˜ 10, agrees well with previous numerical studies and is consistent with the observed estimates for Pop II SFRDs. The mean Pop III metallicity rises smoothly from z = 25 to 7, but does not reach the critical metallicity value, Zcrit = 10-4 Z⊙, required for the Pop III to Pop II transition in star formation mode until z ≃ 7. This suggests that, while individual haloes can suppress in situ Pop III star formation, the external enrichment is insufficient to globally terminate Pop III star formation. The maximum enrichment from Pop III star formation in star-forming dark matter haloes is Z ˜ 10-2 Z⊙, whereas the minimum found in externally enriched haloes is Z ≳ 10-7 Z⊙. Finally, mock observations of our simulated IGM enriched with Pop III metals produce equivalent widths similar to observations of an extremely metal-poor damped Lyman alpha system at z = 7.04, which is thought to be enriched by Pop III star formation only.

Nouveau pôle paléomagnétique Stephanien inférieur pour le craton saharien (formation de Merkala, bassin de Tindouf, Algérie). New Lower Stephanian palaeomagnetic pole for the Sabaran craton (Merkala formation, Tindouf basin, Algeria)

NASA Astrophysics Data System (ADS)

Henry, Bernard; Merabet, Nacer-Eddine; Bouabdallah, Hamza; Maouche, Said

1999-08-01

A palaeomagnetic study carried out in the Lower Stephanian Merkala formation (Tindouf basin) pointed out two juxtaposed neighbouring components of the magnetization. The oldest one allowed a new Stephanian pole located at 32.4°S and 56.6°E ( K= 399, A9.5 = 2.3°) to be obtained. The other one results from the superimposition of this old component on a Permian remagnetization. The new Stephanian pole, associated with the previous data from the Saharan craton, allows the Stephano-Autunian segment of the African apparent polar wander path to be specified.

Barium isotope fractionation during experimental formation of the double carbonate BaMn[CO3](2) at ambient temperature.

PubMed

Böttcher, Michael E; Geprägs, Patrizia; Neubert, Nadja; von Allmen, Katja; Pretet, Chloé; Samankassou, Elias; Nägler, Thomas F

2012-09-01

In this study, we present the first experimental results for stable barium (Ba) isotope ((137)Ba/(134)Ba) fractionation during low-temperature formation of the anhydrous double carbonate BaMn[CO(3)](2). This investigation is part of an ongoing work on Ba fractionation in the natural barium cycle. Precipitation at a temperature of 21±1°C leads to an enrichment of the lighter Ba isotope described by an enrichment factor of-0.11±0.06‰ in the double carbonate than in an aqueous barium-manganese(II) chloride/sodium bicarbonate solution, which is within the range of previous reports for synthetic pure BaCO (3) (witherite) formation.

Negative ion formation in potassium-nitromethane collisions.

PubMed

Antunes, R; Almeida, D; Martins, G; Mason, N J; Garcia, G; Maneira, M J P; Nunes, Y; Limão-Vieira, P

2010-10-21

Ion-pair formation in gaseous nitromethane (CH(3)NO(2)) induced by electron transfer has been studied by investigating the products of collisions between fast potassium atoms and nitromethane molecules using a crossed molecular-beam technique. The negative ions formed in such collisions were analysed using time-of-flight mass spectroscopy. The six most dominant product anions are NO(2)(-), O(-), CH(3)NO(2)(-), OH(-), CH(2)NO(2)(-) and CNO(-). By using nitromethane-d(3) (CD(3)NO(2)), we found that previous mass 17 amu assignment to O(-) delayed fragment, is in the present experiment may be unambiguously assigned to OH(-). The formation of CH(2)NO(2)(-) may be explained in terms of dissociative electron attachment to highly vibrationally excited molecules.

Disentangling stereotype activation and stereotype application in the stereotype misperception task.

PubMed

Krieglmeyer, Regina; Sherman, Jeffrey W

2012-08-01

When forming impressions about other people, stereotypes about the individual's social group often influence the resulting impression. At least 2 distinguishable processes underlie stereotypic impression formation: stereotype activation and stereotype application. Most previous research has used implicit measures to assess stereotype activation and explicit measures to assess stereotype application, which has several disadvantages. The authors propose a measure of stereotypic impression formation, the stereotype misperception task (SMT), together with a multinomial model that quantitatively disentangles the contributions of stereotype activation and application to responses in the SMT. The validity of the SMT and of the multinomial model was confirmed in 5 studies. The authors hope to advance research on stereotyping by providing a measurement tool that separates multiple processes underlying impression formation.

Formation of laser-induced periodic surface structures on fused silica upon two-color double-pulse irradiation

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

Höhm, S.; Herzlieb, M.; Rosenfeld, A.

2013-12-16

The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of fused silica with multiple irradiation sequences consisting of laser pulse pairs (50 fs single-pulse duration) of two different wavelengths (400 and 800 nm) is studied experimentally. Parallel polarized double-pulse sequences with a variable delay Δt between −10 and +10 ps and between the individual fs-laser pulses were used to investigate the LIPSS periods versus Δt. These two-color experiments reveal the importance of the ultrafast energy deposition to the silica surface by the first laser pulse for LIPSS formation. The second laser pulse subsequently reinforces the previously seeded spatial LIPSSmore » frequencies.« less

Corneal haze following PRK with mitomycin C as a retreatment versus prophylactic use in the contralateral eye.

PubMed

Netto, Marcelo V; Chalita, Maria Regina; Krueger, Ronald R

2007-01-01

To report photorefractive keratectomy (PRK) treated with mitomycin C (MMC) for previous corneal haze in one eye and PRK with MMC to prevent corneal haze formation in the fellow eye. A 40-year-old woman underwent PRK with MMC to treat previous corneal haze (secondary to previous PRK without MMC) for residual refractive error of +0.50 +0.25 x 165 in the left eye and PRK with MMC to prevent corneal haze in the right eye. Postoperative slit-lamp examination revealed no haze in the right eye, but continued mild haze in the left eye. Treatment with PRK and MMC for previous corneal haze is not as effective as primary PRK with MMC in preventing postoperative corneal haze formation.

Implicit face prototype learning from geometric information.

PubMed

Or, Charles C-F; Wilson, Hugh R

2013-04-19

There is evidence that humans implicitly learn an average or prototype of previously studied faces, as the unseen face prototype is falsely recognized as having been learned (Solso & McCarthy, 1981). Here we investigated the extent and nature of face prototype formation where observers' memory was tested after they studied synthetic faces defined purely in geometric terms in a multidimensional face space. We found a strong prototype effect: The basic results showed that the unseen prototype averaged from the studied faces was falsely identified as learned at a rate of 86.3%, whereas individual studied faces were identified correctly 66.3% of the time and the distractors were incorrectly identified as having been learned only 32.4% of the time. This prototype learning lasted at least 1 week. Face prototype learning occurred even when the studied faces were further from the unseen prototype than the median variation in the population. Prototype memory formation was evident in addition to memory formation of studied face exemplars as demonstrated in our models. Additional studies showed that the prototype effect can be generalized across viewpoints, and head shape and internal features separately contribute to prototype formation. Thus, implicit face prototype extraction in a multidimensional space is a very general aspect of geometric face learning. Copyright © 2013 Elsevier Ltd. All rights reserved.

How Need for Cognition Affects the Formation of Performance Expectancies at School

ERIC Educational Resources Information Center

Dickhauser, Oliver; Reinhard, Marc-Andre

2009-01-01

Individuals with low Need for Cognition (NFC) have been found to process information using a peripheral route compared to individuals higher in NFC. These differences affect the formation of performance expectancies. Based on previous work demonstrating that the formation of performance expectancies can be understood as an information processing…

The Higher Learning and High Technology: Dynamics of Higher Education Policy Formation.

ERIC Educational Resources Information Center

Slaughter, Sheila

An examination of national higher education policy formation focuses on the shift in relationships of the central actors in the policy formation process. It is argued that whereas the federal government, together with the scientific community and foundations, previously had the dominant voice, the corporate community, in partnership with leaders…

Lymphogranuloma venereum: a rare and forgotten cause of rectal stricture formation.

PubMed

Craxford, Leia; Fox, Ashini

2018-01-01

Lymphogranuloma venereum (LGV) is caused by L1, L2 and L3 serovars of Chlamydia trachomatis. The anorectal syndrome caused by LGV is often misdiagnosed as inflammatory bowel disease and may rarely lead to stricture formation. Recurrent stricture formation, despite adequate LGV treatment, has not to our knowledge, previously been reported.

12 CFR 335.801 - Inapplicable SEC regulations; FDIC substituted regulations; additional information.

Code of Federal Regulations, 2013 CFR

2013-01-01

... a continuing hardship exemption under these rules may file the forms with the FDIC in paper format... these rules may file the appropriate forms with the FDIC in paper format. Instructions for continuing...) Previously filed exhibits, whether in paper or electronic format, may be incorporated by reference into an...

12 CFR 335.801 - Inapplicable SEC regulations; FDIC substituted regulations; additional information.

Code of Federal Regulations, 2014 CFR

2014-01-01

... a continuing hardship exemption under these rules may file the forms with the FDIC in paper format... these rules may file the appropriate forms with the FDIC in paper format. Instructions for continuing...) Previously filed exhibits, whether in paper or electronic format, may be incorporated by reference into an...

12 CFR 335.801 - Inapplicable SEC regulations; FDIC substituted regulations; additional information.

Code of Federal Regulations, 2012 CFR

2012-01-01

... a continuing hardship exemption under these rules may file the forms with the FDIC in paper format... these rules may file the appropriate forms with the FDIC in paper format. Instructions for continuing...) Previously filed exhibits, whether in paper or electronic format, may be incorporated by reference into an...

12 CFR 335.801 - Inapplicable SEC regulations; FDIC substituted regulations; additional information.

Code of Federal Regulations, 2011 CFR

2011-01-01

... a continuing hardship exemption under these rules may file the forms with the FDIC in paper format... these rules may file the appropriate forms with the FDIC in paper format. Instructions for continuing...) Previously filed exhibits, whether in paper or electronic format, may be incorporated by reference into an...

Electron ionization of SiCl4

NASA Astrophysics Data System (ADS)

King, Simon J.; Price, Stephen D.

2011-02-01

Relative partial ionization cross sections (PICS) for the formation of fragment ions following electron ionization of SiCl4, in the electron energy range 30-200 eV, have been determined using time-of-flight mass spectrometry coupled with an ion coincidence technique. By this method, the contributions to the yield of each fragment ion from dissociative single, double, and triple ionization, are distinguished. These yields are quantified in the form of relative precursor-specific PICS, which are reported here for the first time for SiCl4. For the formation of singly charged ionic fragments, the low-energy maxima appearing in the PICS curves are due to contributions from single ionization involving predominantly indirect ionization processes, while contributions to the yields of these ions at higher electron energies are often dominated by dissociative double ionization. Our data, in the reduced form of relative PICS, are shown to be in good agreement with a previous determination of the PICS of SiCl4. Only for the formation of doubly charged fragment ions are the current relative PICS values lower than those measured in a previous study, although both datasets agree within combined error limits. The relative PICS data presented here include the first quantitative measurements of the formation of Cl2+ fragment ions and of the formation of ion pairs via dissociative double ionization. The peaks appearing in the 2D ion coincidence data are analyzed to provide further information concerning the mechanism and energetics of the charge-separating dissociations of SiCl42+. The lowest energy dicationic precursor state, leading to SiCl3+ + Cl+ formation, lies 27.4 ± 0.3 eV above the ground state of SiCl4 and is in close agreement with a calculated value of the adiabatic double ionization energy (27.3 eV).

Electron ionization of SiCl4.

PubMed

King, Simon J; Price, Stephen D

2011-02-21

Relative partial ionization cross sections (PICS) for the formation of fragment ions following electron ionization of SiCl(4), in the electron energy range 30-200 eV, have been determined using time-of-flight mass spectrometry coupled with an ion coincidence technique. By this method, the contributions to the yield of each fragment ion from dissociative single, double, and triple ionization, are distinguished. These yields are quantified in the form of relative precursor-specific PICS, which are reported here for the first time for SiCl(4). For the formation of singly charged ionic fragments, the low-energy maxima appearing in the PICS curves are due to contributions from single ionization involving predominantly indirect ionization processes, while contributions to the yields of these ions at higher electron energies are often dominated by dissociative double ionization. Our data, in the reduced form of relative PICS, are shown to be in good agreement with a previous determination of the PICS of SiCl(4). Only for the formation of doubly charged fragment ions are the current relative PICS values lower than those measured in a previous study, although both datasets agree within combined error limits. The relative PICS data presented here include the first quantitative measurements of the formation of Cl(2) (+) fragment ions and of the formation of ion pairs via dissociative double ionization. The peaks appearing in the 2D ion coincidence data are analyzed to provide further information concerning the mechanism and energetics of the charge-separating dissociations of SiCl(4) (2+). The lowest energy dicationic precursor state, leading to SiCl(3) (+) + Cl(+) formation, lies 27.4 ± 0.3 eV above the ground state of SiCl(4) and is in close agreement with a calculated value of the adiabatic double ionization energy (27.3 eV).

Ichnology applied to sequence stratigraphic analysis of Siluro-Devonian mud-dominated shelf deposits, Paraná Basin, Brazil

NASA Astrophysics Data System (ADS)

Sedorko, Daniel; Netto, Renata G.; Savrda, Charles E.

2018-04-01

Previous studies of the Paraná Supersequence (Furnas and Ponta Grossa formations) of the Paraná Basin in southern Brazil have yielded disparate sequence stratigraphic interpretations. An integrated sedimentological, paleontological, and ichnological model was created to establish a refined sequence stratigraphic framework for this succession, focusing on the Ponta Grossa Formation. Twenty-nine ichnotaxa are recognized in the Ponta Grossa Formation, recurring assemblages of which define five trace fossil suites that represent various expressions of the Skolithos, Glossifungites and Cruziana ichnofacies. Physical sedimentologic characteristics and associated softground ichnofacies provide the basis for recognizing seven facies that reflect a passive relationship to bathymetric gradients from shallow marine (shoreface) to offshore deposition. The vertical distribution of facies provides the basis for dividing the Ponta Grossa Formation into three major (3rd-order) depositional sequences- Siluro-Devonian and Devonian I and II-each containing a record of three to seven higher-order relative sea-level cycles. Major sequence boundaries, commonly coinciding with hiatuses recognized from previously published biostratigraphic data, are locally marked by firmground Glossifungites Ichnofacies associated with submarine erosion. Maximum transgressive horizons are prominently marked by unbioturbated or weakly bioturbated black shales. By integrating observations of the Ponta Grossa Formation with those recently made on the underlying marginal- to shallow-marine Furnas Formation, the entire Paraná Supersequence can be divided into four disconformity-bound sequences: a Lower Silurian (Llandovery-Wenlock) sequence, corresponding to lower and middle units of the Furnas; a Siluro-Devonian sequence (?Pridoli-Early Emsian), and Devonian sequences I (Late Emsian-Late Eifelian) and II (Late Eifelian-Early Givetian). Stratigraphic positions of sequence boundaries generally coincide with regressive phases on established global sea-level curves for the Silurian-Devonian.

Inhibitory effects of yuzu and its components on human platelet aggregation.

PubMed

Kim, Tae-Ho; Kim, Hye-Min; Park, Se Won; Jung, Yi-Sook

2015-03-01

Our previous study demonstrated that yuzu has an anti-platelet effect in rat blood. In the present study, we examined whether the anti-platelet effect of yuzu can be extended to human blood by investigating its ability to inhibit aggregations induced by various agonists in human platelet rich plasma (PRP). This study also investigated the underlying mechanism of yuzu focusing on ADP granule secretion, TXB2 formations, and PLCγ/Akt signaling. The results from this study showed that ethanolic yuzu extract (YE), and its components, hesperidin and naringin, inhibited human platelet aggregation in a concentration-dependent manner. YE, hesperidin and naringin also inhibited TXB2 formation and ADP release. The phosphorylation of PLCγ and Akt was significantly inhibited by YE, heperidin and naringin. Furthermore, we demonstrated that YE, heperidin and naringin has anti-platelet effects in rat ex vivo studies, and lower side effects in mice tail bleeding time studies. The results from this study suggest that YE, hesperidin and naringin can inhibit human platelet aggregation, at least partly through the inhibition of PLCγ and Akt, leading to a decrease in TXB2 formation and granule secretion.

Lipid droplets formation in human endothelial cells in response to polyunsaturated fatty acids and 1-methyl-nicotinamide (MNA); confocal Raman imaging and fluorescence microscopy studies.

PubMed

Majzner, Katarzyna; Chlopicki, Stefan; Baranska, Malgorzata

2016-04-01

In this work the formation of lipid droplets (LDs) in human endothelial cells culture in response to the uptake of polyunsaturated fatty acids (PUFAs) was studied. Additionally, an effect of 1-methylnicotinamide (MNA) on the process of LDs formation was investigated. LDs have been previously described structurally and to some degree biochemically, however neither the precise function of LDs nor the factors responsible for LD induction have been clarified. Lipid droplets, sometimes referred in the literature as lipid bodies are organelles known to regulate neutrophil, eosinophil, or tumor cell functions but their presence and function in the endothelium is largely unexplored. 3D linear Raman spectroscopy was used to study LDs formation in vitro in a single endothelial cell. The method provides information about distribution and size of LDs as well as their composition. The incubation of endothelial cells with various PUFAs resulted in formation of LDs. As a complementary method for LDs identification a fluorescence microscopy was applied. Fluorescence measurements confirmed the Raman results suggesting endothelial cells uptake of PUFAs and subsequent LDs formation in the cytoplasm of the endothelium. Furthermore, MNA seem to potentiate intracellular uptake of PUFAs to the endothelium that may bear physiological and pharmacological significance. Confocal Raman imaging of HAoEC cell with LDs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Formation evaluation in liquid-dominated geothermal reservoirs

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

Ershaghi, I.; Dougherty, E.E.; Handy, L.L.

1981-04-01

Studies relative to some formation evaluation aspects of geothermal reservoirs are reported. The particular reservoirs considered were the liquid dominated type with a lithology of the sedimentary nature. Specific problems of interest included the resistivity behavior of brines and rocks at elevated temperatures and studies on the feasibility of using the well log resistivity data to obtain estimates of reservoir permeability. Several papers summarizing the results of these studies were presented at various technical meetings for rapid dissemination of the results to potential users. These papers together with a summary of data most recently generated are included. A brief reviewmore » of the research findings precedes the technical papers. Separate abstracts were prepared for four papers. Five papers were abstracted previously for EDB.« less

Point defects in thorium nitride: A first-principles study

NASA Astrophysics Data System (ADS)

Pérez Daroca, D.; Llois, A. M.; Mosca, H. O.

2016-11-01

Thorium and its compounds (carbides and nitrides) are being investigated as possible materials to be used as nuclear fuels for Generation-IV reactors. As a first step in the research of these materials under irradiation, we study the formation energies and stability of point defects in thorium nitride by means of first-principles calculations within the framework of density functional theory. We focus on vacancies, interstitials, Frenkel pairs and Schottky defects. We found that N and Th vacancies have almost the same formation energy and that the most energetically favorable defects of all studied in this work are N interstitials. These kind of results for ThN, to the best authors' knowledge, have not been obtained previously, neither experimentally, nor theoretically.

Globular cluster formation - The fossil record

NASA Technical Reports Server (NTRS)

Murray, Stephen D.; Lin, Douglas N. C.

1992-01-01

Properties of globular clusters which have remained unchanged since their formation are used to infer the internal pressures, cooling times, and dynamical times of the protocluster clouds immediately prior to the onset of star formation. For all globular clusters examined, it is found that the cooling times are much less than the dynamical times, implying that the protoclusters must have been maintained in thermal equilibrium by external heat sources, with fluxes consistent with those found in previous work, and giving the observed rho-T relation. Self-gravitating clouds cannot be stably heated, so that the Jeans mass forms an upper limit to the cluster masses. The observed dependence of protocluster pressure upon galactocentric position implies that the protocluster clouds were in hydrostatic equilibrium after their formation. The pressure dependence is well fitted by that expected for a quasi-statically evolving background hot gas, shock heated to its virial temperature. The observations and inferences are combined with previous theoretical work to construct a picture of globular cluster formation.

Extracellular DNA facilitates the formation of functional amyloids in Staphylococcus aureus biofilms.

PubMed

Schwartz, Kelly; Ganesan, Mahesh; Payne, David E; Solomon, Michael J; Boles, Blaise R

2016-01-01

Persistent staphylococcal infections often involve surface-associated communities called biofilms. Staphylococcus aureus biofilm development is mediated by the co-ordinated production of the biofilm matrix, which can be composed of polysaccharides, extracellular DNA (eDNA) and proteins including amyloid fibers. The nature of the interactions between matrix components, and how these interactions contribute to the formation of matrix, remain unclear. Here we show that the presence of eDNA in S. aureus biofilms promotes the formation of amyloid fibers. Conditions or mutants that do not generate eDNA result in lack of amyloids during biofilm growth despite the amyloidogeneic subunits, phenol soluble modulin peptides, being produced. In vitro studies revealed that the presence of DNA promotes amyloid formation by PSM peptides. Thus, this work exposes a previously unacknowledged interaction between biofilm matrix components that furthers our understanding of functional amyloid formation and S. aureus biofilm biology. © 2015 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.

A possible mechanism of maxillofacial abscess formation: involvement of Porphyromonas endodontalis lipopolysaccharide via the expression of inflammatory cytokines.

PubMed

Murakami, Y; Hanazawa, S; Tanaka, S; Iwahashi, H; Yamamoto, Y; Fujisawa, S

2001-12-01

In a previous study, we developed a specific monoclonal antibody against Porphyromonas endodontalis lipopolysaccharide, and demonstrated that this lipopolysaccharide was detected in bacterially infected root canal fluid. We suggest here that P. endodontalis lipopolysaccharide in the infectious materials plays a stimulatory role in maxillofacial abscess formation via the expression of inflammatory cytokines. Our epidemiological study showed that this lipopolysaccharide was detected in significant levels the infectious material of patients with periapical periodontitis and odontogenic abscesses. Interestingly, infectious material-induced expression of tumor necrosis factor-alpha, interleukin-1beta, or neutrophil chemoattractant KC genes in mouse macrophages, was significantly neutralized by monoclonal antibody against the lipopolysaccharide. In addition, we also detected a significant amount of tumor necrosis factor-alpha in the infectious material. These results suggest that P. endodontalis lipopolysaccharide plays an important role in the pathogenic mechanism of maxillofacial abscess formation via the expression of inflammatory cytokines.

Impact of nanosecond pulsed electric fields on primary hippocampal neurons

NASA Astrophysics Data System (ADS)

Roth, Caleb C.; Payne, Jason A.; Kuipers, Marjorie A.; Thompson, Gary L.; Wilmink, Gerald J.; Ibey, Bennett L.

2012-02-01

Cellular exposure to nanosecond pulsed electric fields (nsPEF) are believed to cause immediate creation of nanopores in the plasma membrane. These nanopores enable passage of small ions, but remain impermeable to larger molecules like propidium iodide. Previous work has shown that nanopores are stable for minutes after exposure, suggesting that formation of nanopores in excitable cells could lead to prolonged action potential inhibition. Previously, we measured the formation of nanopores in neuroblastoma cells by measuring the influx of extracellular calcium by preloading cells with Calcium Green-AM. In this work, we explored the impact of changing the width of a single nsPEF, at constant amplitude, on uptake of extracellular calcium ions by primary hippocampal neurons (PHN). Calcium Green was again used to measure the influx of extracellular calcium and FM1-43 was used to monitor changes in membrane conformation. The observed thresholds for nanopore formation in PHN by nsPEF were comparable to those measured in neuroblastoma. This work is the first study of nsPEF effects on PHN and strongly suggests that neurological inhibition by nanosecond electrical pulses is highly likely at doses well below irreversible damage.

Late Cretaceous paleosols as paleoclimate proxies of high-latitude Southern Hemisphere: Mata Amarilla Formation, Patagonia, Argentina

NASA Astrophysics Data System (ADS)

Varela, Augusto N.; Raigemborn, M. Sol; Richiano, Sebastián; White, Tim; Poiré, Daniel G.; Lizzoli, Sabrina

2018-01-01

Although there is general consensus that a global greenhouse climate characterized the mid-Cretaceous, details of the climate state of the mid-Cretaceous Southern Hemisphere are less clearly understood. In particular, continental paleoclimate reconstructions are scarce and exclusively derived from paleontological records. Using paleosol-derived climofunction studies of the mid- to Upper Cretaceous Mata Amarilla Formation, southern Patagonia, Argentina, we present a reconstruction of the mid-Cretaceous climate of southern South America. Our results indicate that at 60° south paleolatitude during the Cenomanian-Santonian stages, the climate was subtropical temperate-warm (12 °C ± 2.1 °C) and humid (1404 ± 108 mm/yr) with marked rainfall seasonality. These results are consistent with both previous estimations from the fossil floras of the Mata Amarilla Formation and other units of the Southern Hemisphere, and with the previous observations of the displacement of tropical and subtropical floras towards the poles in both hemispheres. The data presented here show a more marked seasonality and slightly lower mean annual precipitation and mean annual temperature values than those recorded at the same paleolatitudes in the Northern Hemisphere.

Pre-, syn-, and postcollisional stratigraphic framework and provenance of upper triassic-upper cretaceous strata in the northwestern talkeetna mountains, alaska

USGS Publications Warehouse

Hampton, B.A.; Ridgway, K.D.; O'Neill, J. M.; Gehrels, G.E.; Schmidt, J.; Blodgett, R.B.

2007-01-01

Mesozoic strata of the northwestern Talkeetna Mountains are located in a regional suture zone between the allochthonous Wrangellia composite terrane and the former Mesozoic continental margin of North America (i.e., the Yukon-Tanana terrane). New geologic mapping, measured stratigraphic sections, and provenance data define a distinct three-part stratigraphy for these strata. The lowermost unit is greater than 290 m thick and consists of Upper Triassic-Lower Jurassic mafic lavas, fossiliferous limestone, and a volcaniclastic unit that collectively we informally refer to as the Honolulu Pass formation. The uppermost 75 m of the Honolulu Pass formation represent a condensed stratigraphic interval that records limited sedimentation over a period of up to ca. 25 m.y. during Early Jurassic time. The contact between the Honolulu Pass formation and the overlying Upper Jurassic-Lower Cretaceous clastic marine strata of the Kahiltna assemblage represents a ca. 20 m.y. depositional hiatus that spans the Middle Jurassic and part of Late Jurassic time. The Kahiltna assemblage may to be up to 3000 m thick and contains detrital zircons that have a robust U-Pb peak probability age of 119.2 Ma (i.e., minimum crystallization age/maximum depositional age). These data suggest that the upper age of the Kahiltna assemblage may be a minimum of 10-15 m.y. younger than the previously reported upper age of Valanginian. Sandstone composition (Q-43% F-30% L-27%-Lv-71% Lm-18% Ls-11%) and U-Pb detrital zircon ages suggest that the Kahiltna assemblage received igneous detritus mainly from the active Chisana arc, remnant Chitina and Talkeetna arcs, and Permian-Triassic plutons (Alexander terrane) of the Wrangellia composite terrane. Other sources of detritus for the Kahiltna assemblage were Upper Triassic-Lower Jurassic plutons of the Taylor Mountains batholith and Devonian-Mississippian plutons; both of these source areas are part of the Yukon-Tanana terrane. The Kahiltna assemblage is overlain by previously unrecognized nonmarine strata informally referred to here as the Caribou Pass formation. This unit is at least 250 m thick and has been tentatively assigned an Albian-Cenomanian-to-younger age based on limited palynomorphs and fossil leaves. Sandstone composition (Q-65% F-9% L-26%-Lv-28% Lm-52% Ls-20%) from this unit suggests a quartz-rich metamorphic source terrane that we interpret as having been the Yukon-Tanana terrane. Collectively, provenance data indicate that there was a fundamental shift from mainly arc-related sediment derivation from sources located south of the study area during Jurassic-Early Cretaceous (Aptian) time (Kahiltna assemblage) to mainly continental margin-derived sediment from sources located north and east of the study area by Albian-Cenomanian time (Caribou Pass formation). We interpret the threepart stratigraphy defined for the northwestern Talkeetna Mountains to represent pre- (the Honolulu Pass formation), syn- (the Kahiltna assemblage), and post- (the Caribou Pass formation) collision of the Wrangellia composite terrane with the Mesozoic continental margin. A similar Mesozoic stratigraphy appears to exist in other parts of south-central and southwestern Alaska along the suture zone based on previous regional mapping studies. New geologic mapping utilizing the three-part stratigraphy interprets the northwestern Talkeetna Mountains as consisting of two northwest-verging thrust sheets. Our structural interpretation is that of more localized thrust-fault imbrication of the three-part stratigraphy in contrast to previous interpretations of nappe emplacement or terrane translation that require large-scale displacements. Copyright ?? 2007 The Geological Society of America.

Detergent-Mediated Formation of β-Hematin: Heme Crystallization Promoted by Detergents Implicates Nanostructure Formation for Use as a Biological Mimic

PubMed Central

2016-01-01

Hemozoin is a unique biomineral that results from the sequestration of toxic free heme liberated as a consequence of hemoglobin degradation in the malaria parasite. Synthetic neutral lipid droplets (SNLDs) and phospholipids were previously shown to support the rapid formation of β-hematin, abiological hemozoin, under physiologically relevant pH and temperature, though the mechanism by which heme crystallization occurs remains unclear. Detergents are particularly interesting as a template because they are amphiphilic molecules that spontaneously organize into nanostructures and have been previously shown to mediate β-hematin formation. Here, 11 detergents were investigated to elucidate the physicochemical properties that best recapitulate crystal formation in the parasite. A strong correlation between the detergent’s molecular structure and the corresponding kinetics of β-hematin formation was observed, where higher molecular weight polar chains promoted faster reactions. The larger hydrophilic chains correlated to the detergent’s ability to rapidly sequester heme into the lipophilic core, allowing for crystal nucleation to occur. The data presented here suggest that detergent nanostructures promote β-hematin formation in a similar manner to SNLDs and phospholipids. Through understanding mediator properties that promote optimal crystal formation, we are able to establish an in vitro assay to probe this drug target pathway. PMID:27175104

Equivalence of electronic and paper-based patient-reported outcome measures.

PubMed

Campbell, Niloufar; Ali, Faraz; Finlay, Andrew Y; Salek, Sam S

2015-08-01

Electronic formats (ePROs) of paper-based patient-reported outcomes (PROs) should be validated before they can be reliably used. This review aimed to examine studies investigating measurement equivalence between ePROs and their paper originals to identify methodologies used and to determine the extent of such validation. Three databases (OvidSP, Web of Science and PubMed) were searched using a set of keywords. Results were examined for compliance with inclusion criteria. Articles or abstracts that directly compared screen-based electronic versions of PROs with their validated paper-based originals, with regard to their measurement equivalence, were included. Publications were excluded if the only instruments reported were stand-alone visual analogue scales or interactive voice response formats. Papers published before 2007 were excluded, as a previous meta-analysis examined papers published before this time. Fifty-five studies investigating 79 instruments met the inclusion criteria. 53 % of the 79 instruments studied were condition specific. Several instruments, such as the SF-36, were reported in more than one publication. The most frequently reported formats for ePROs were Web-based versions. In 78 % of the publications, there was evidence of equivalence or comparability between the two formats as judged by study authors. Of the 30 publications that provided preference data, 87 % found that overall participants preferred the electronic format. When examining equivalence between paper and electronic versions of PROs, formats are usually judged by authors to be equivalent. Participants prefer electronic formats. This literature review gives encouragement to the further widespread development and use of ePROs.

NDMA formation during chlorination and chloramination of aqueous diuron solutions.

PubMed

Chen, Wei-Hsiang; Young, Thomas M

2008-02-15

Formation of the potent carcinogen N-nitrosodimethylamine (NDMA) during chlorine disinfection of water containing secondary amines is now generally acknowledged. The phenylurea herbicide diuron is one of the most widely used herbicides in California, has been frequently detected in California's water sources with a transient nature of appearance, and has a structure that suggests it might be an NDMA precursor. This study sought to quantify the potential for NDMA formation from aqueous diuron solutions under varied chlorine and chloramine conditions. NDMA formation was consistently observed even in the absence of added ammonia, which has usually been the source of the nitroso-nitrogen during chloramination of other precursors. It appears that both nitrogen atoms in NDMA are donated by diuron during chlorination in the absence of added ammonia. For a given chlorine and diuron dose, NDMA formation increased in the order OCl- < NH2Cl < NHCl2, a result consistentwith previous NDMAformation studies. Significant quantities of NDMA (170 ng/L) were produced during dichloramination of diuron using a low dichloramine concentration and a diuron concentration at the upper end of typically detected concentrations in California (20 microg/L), suggesting a need for further investigation to accurately assess the human health risks posed by diuron with respect to NDMA formation potential. A reaction pathway is proposed to provide a possible explanation for NDMA formation from diuron during chlorination or chloramination. The findings in this study identify a specific potential precursor of NDMA formation, one that arises from nonpoint sources. This further highlights the difficulties associated with determining the environmental safety of chemicals and their associated byproducts.

Extrasynaptic GABAA Receptors in Rat Pontine Reticular Formation Increase Wakefulness

PubMed Central

Vanini, Giancarlo; Baghdoyan, Helen A.

2013-01-01

Study Objectives: Gamma-aminobutyric acid (GABA) causes phasic inhibition via synaptic GABAA receptors and tonic inhibition via extrasynaptic GABAA receptors. GABA levels in the extracellular space regulate arousal state and cognition by volume transmission via extrasynaptic GABAA receptors. GABAergic transmission in the pontine reticular formation promotes wakefulness. No previous studies have determined whether an agonist at extrasynaptic GABAA receptors administered into the pontine reticular formation alters sleep and wakefulness. Therefore, this study used gaboxadol (THIP; agonist at extrasynaptic GABAA receptors that contain a δ subunit) to test the hypothesis that extrasynaptic GABAA receptors within the pontine reticular formation modulate sleep and wakefulness. Design: Within/between subjects. Setting: University of Michigan. Patients or Participants: Adult male Crl:CD*(SD) (Sprague-Dawley) rats (n = 10). Interventions: Microinjection of gaboxadol, the nonsubtype selective GABAA receptor agonist muscimol (positive control), and saline (negative control) into the rostral pontine reticular formation. Measurements and Results: Gaboxadol significantly increased wakefulness and decreased both nonrapid eye movement sleep and rapid eye movement sleep in a concentration-dependent manner. Relative to saline, gaboxadol did not alter electroencephalogram power. Microinjection of muscimol into the pontine reticular formation of the same rats that received gaboxadol increased wakefulness and decreased sleep. Conclusion: Tonic inhibition via extrasynaptic GABAA receptors that contain a δ subunit may be one mechanism by which the extracellular pool of endogenous GABA in the rostral pontine reticular formation promotes wakefulness. Citation: Vanini G; Baghdoyan HA. Extrasynaptic GABAA receptors in rat pontine reticular formation increase wakefulness. SLEEP 2013;36(3):337-343. PMID:23450652

Formation of Copper Catalysts for CO 2 Reduction with High Ethylene/Methane Product Ratio Investigated with In Situ X-ray Absorption Spectroscopy

DOE PAGES

Eilert, André; Roberts, F. Sloan; Friebel, Daniel; ...

2016-04-04

Nanostructured copper cathodes are among the most efficient and selective catalysts to date for making multicarbon products from the electrochemical carbon dioxide reduction reaction (CO 2RR). We report an in situ X-ray absorption spectroscopy investigation of the formation of a copper nanocube CO 2RR catalyst with high activity that highly favors ethylene over methane production. The results show that the precursor for the copper nanocube formation is copper(I)-oxide, not copper(I)-chloride as previously assumed. A second route to an electrochemically similar material via a copper(II)–carbonate/hydroxide is also reported. In conclusion, this study highlights the importance of using oxidized copper precursors formore » constructing selective CO 2 reduction catalysts and shows the precursor oxidation state does not affect the electrocatalyst selectivity toward ethylene formation.« less

Promoting cooperation by reputation-driven group formation

NASA Astrophysics Data System (ADS)

Yang, Han-Xin; Wang, Zhen

2017-02-01

In previous studies of the spatial public goods game, each player is able to establish a group. However, in real life, some players cannot successfully organize groups for various reasons. In this paper, we propose a mechanism of reputation-driven group formation, in which groups can only be organized by players whose reputation reaches or exceeds a threshold. We define a player’s reputation as the frequency of cooperation in the last T time steps. We find that the highest cooperation level can be obtained when groups are only established by pure cooperators who always cooperate in the last T time steps. Effects of the memory length T on cooperation are also studied.

Role of disulfide cross-linking of mutant SOD1 in the formation of inclusion-body-like structures.

PubMed

Roberts, Brittany L T; Patel, Kinaree; Brown, Hilda H; Borchelt, David R

2012-01-01

Pathologic aggregates of superoxide dismutase 1 (SOD1) harboring mutations linked to familial amyotrophic lateral sclerosis (fALS) have been shown to contain aberrant intermolecular disulfide cross-links. In prior studies, we observed that intermolecular bonding was not necessary in the formation of detergent- insoluble SOD1 complexes by mutant SOD1, but we were unable to assess whether this type of bonding may be important for pathologic inclusion formation. In the present study, we visually assess the formation of large inclusions by fusing mutant SOD1 to yellow fluorescent protein (YFP). Experimental constructs possessing mutations at all cysteine residues in SOD1 (sites 6, 57, 111, and 146 to F,S,Y,R or G,S,Y,R, respectively) were shown to maintain a high propensity of inclusion formation despite the inability to form disulfide cross-links. Interestingly, although aggregates form when all cysteines were mutated, double mutants of the ALS mutation C6G with an experimental mutation C111S exhibited low aggregation propensity. Overall, this study is an extension of previous work demonstrating that cysteine residues in mutant SOD1 play a role in modulating aggregation and that intermolecular disulfide bonds are not required to produce large intracellular inclusion-like structures.

Characterizing the Protostars in the Herschel Survey of Cygnus-X

NASA Astrophysics Data System (ADS)

Kirk, James; Hora, J. L.; Smith, H. A.; Herschel Cygnus-X Group

2014-01-01

The Cygnus-X complex is an extremely active region of massive star formation at a distance of ~1.4 kpc which can be studied with higher sensitivity and less confusion than more distant regions. The study of this region is important in improving our understanding of the formation processes and protostellar phases of massive stars. A previous Spitzer Legacy survey of Cygnus-X mapped the distributions of Class I and Class II YSOs within the region and studied the interaction between massive young stars and clusters of YSOs. Using data from the recent Herschel survey of the region, taken with the PACS and SPIRE instrument (70-500 microns), we are expanding this study of star formation to the youngest and most deeply embedded objects. Using these data we will expand the sample of massive protostars and YSOs in Cygnus-X, analyze the population of infrared dark clouds and their embedded objects, construct Spectral Energy Distributions (SEDs) using pre-existing Spitzer and near-IR data sets (1-500 microns), and fit these sources with models of protostars to derive luminosities and envelope masses. The derived luminosities and masses will enable us to create evolutionary diagrams and test models of high-mass star formation. We will also investigate what role OB associations, such as Cyg OB2, play in causing subsequent star formation in neighboring clouds, providing us with a comprehensive picture of star formation within this extremely active complex.

The formation of disc galaxies in high-resolution moving-mesh cosmological simulations

NASA Astrophysics Data System (ADS)

Marinacci, Federico; Pakmor, Rüdiger; Springel, Volker

2014-01-01

We present cosmological hydrodynamical simulations of eight Milky Way-sized haloes that have been previously studied with dark matter only in the Aquarius project. For the first time, we employ the moving-mesh code AREPO in zoom simulations combined with a comprehensive model for galaxy formation physics designed for large cosmological simulations. Our simulations form in most of the eight haloes strongly disc-dominated systems with realistic rotation curves, close to exponential surface density profiles, a stellar mass to halo mass ratio that matches expectations from abundance matching techniques, and galaxy sizes and ages consistent with expectations from large galaxy surveys in the local Universe. There is no evidence for any dark matter core formation in our simulations, even so they include repeated baryonic outflows by supernova-driven winds and black hole quasar feedback. For one of our haloes, the object studied in the recent `Aquila' code comparison project, we carried out a resolution study with our techniques, covering a dynamic range of 64 in mass resolution. Without any change in our feedback parameters, the final galaxy properties are reassuringly similar, in contrast to other modelling techniques used in the field that are inherently resolution dependent. This success in producing realistic disc galaxies is reached, in the context of our interstellar medium treatment, without resorting to a high density threshold for star formation, a low star formation efficiency, or early stellar feedback, factors deemed crucial for disc formation by other recent numerical studies.

Anciet marble quarries in Lesvos island Greece

NASA Astrophysics Data System (ADS)

Mataragkas, M.; Mataragkas, D.

2009-04-01

ANCIENT MARBLE QUARRIES IN LESBOS ISLAND, GREECE Varti- Matarangas M.1 & Matarangas D. 1 Institute of Geological and Mining Exploration (IGME), Olympic Village, Entrance C, ACHARNAE 13677, GREECE myrsini@igme.gr , myrsini@otenet.g r A B S T R A C T Ten ancient marble quarries of Lesbos Island, most of them previously unknown, have been studied, in the frame of the research study on the ancient marble quarries in the Aegean Sea. In the present paper the geological, petrological and morphological features of the aforementioned quarries are examined. Concerning the six ancient quarries located in the areas of Tarti, Agia Paraskevi (Tsaf), Mageiras, Loutra, Latomi (Plomari) and Thermi, the authochthonous neopaleozoic unit constitutes their geological formation, while their hosting lithological formations are the included crystalline limestone lens like beds. In two ancient quarries in the areas Moria and Alyfanta, the geological formation is the authochthonous upper Triassic series and the hosting lithological formation the upper Triassic carbonate sequence, while in the areas of Akrasi-Abeliko and Karyni, the geological formation is the thrust Triassic unit and the lithological hosting formations are the included strongly deformed or not crystalline limestone lenticular beds. Furthermore, the petrographic features were also determined permitting the identification of the building stones that have been used.

Contribution of the Antibiotic Chloramphenicol and Its Analogues as Precursors of Dichloroacetamide and Other Disinfection Byproducts in Drinking Water.

PubMed

Chu, Wenhai; Krasner, Stuart W; Gao, Naiyun; Templeton, Michael R; Yin, Daqiang

2016-01-05

Dichloroacetamide (DCAcAm), a disinfection byproduct, has been detected in drinking water. Previous research showed that amino acids may be DCAcAm precursors. However, other precursors may be present. This study explored the contribution of the antibiotic chloramphenicol (CAP) and two of its analogues (thiamphenicol, TAP; florfenicol, FF) (referred to collectively as CAPs), which occur in wastewater-impacted source waters, to the formation of DCAcAm. Their formation yields were compared to free and combined amino acids, and they were investigated in filtered waters from drinking-water-treatment plants, heavily wastewater-impacted natural waters, and secondary effluents from wastewater treatment plants. CAPs had greater DCAcAm formation potential than two representative amino acid precursors. However, in drinking waters with ng/L levels of CAPs, they will not contribute as much to DCAcAm formation as the μg/L levels of amino acids. Also, the effect of advanced oxidation processes (AOPs) on DCAcAm formation from CAPs in real water samples during subsequent chlorination was evaluated. Preoxidation of CAPs with AOPs reduced the formation of DCAcAm during postchlorination. The results of this study suggest that CAPs should be considered as possible precursors of DCAcAm, especially in heavily wastewater-impacted waters.

Iron-regulated biofilm formation in Staphylococcus aureus Newman requires ica and the secreted protein Emp.

PubMed

Johnson, Miranda; Cockayne, Alan; Morrissey, Julie A

2008-04-01

Staphylococcus aureus biofilm formation is induced in iron-restricted growth conditions in vitro. In this study, we showed that Emp and Eap play important roles in low-iron-induced biofilm formation of S. aureus Newman. Eap and Emp are secreted proteins which are non-covalently attached to the S. aureus cell surface and have previously been implicated in a number of aspects of S. aureus pathogenesis. We showed here that the transcription of these important virulence factors is induced by growth in low-iron medium, reflective of the in vivo environment. Our results show that iron regulation of Eap and Emp is Fur independent. However, Fur is required for full induction of eap and emp expression in low-iron conditions. In this study, we demonstrated that in addition to Fur, low-iron-induced biofilm formation requires Sae, Agr, and SarA. In iron-restricted growth conditions, Sae and Agr are essential for Emp and Eap expression and hence for biofilm formation, whereas SarA appears to have a less-significant role. We also showed that expression of the ica operon is required for biofilm formation in iron-restricted growth conditions. We demonstrated that in fact, ica is required for the expression of the important multifunctional virulence determinants eap and emp.

Iron-Regulated Biofilm Formation in Staphylococcus aureus Newman Requires ica and the Secreted Protein Emp▿

PubMed Central

Johnson, Miranda; Cockayne, Alan; Morrissey, Julie A.

2008-01-01

Staphylococcus aureus biofilm formation is induced in iron-restricted growth conditions in vitro. In this study, we showed that Emp and Eap play important roles in low-iron-induced biofilm formation of S. aureus Newman. Eap and Emp are secreted proteins which are non-covalently attached to the S. aureus cell surface and have previously been implicated in a number of aspects of S. aureus pathogenesis. We showed here that the transcription of these important virulence factors is induced by growth in low-iron medium, reflective of the in vivo environment. Our results show that iron regulation of Eap and Emp is Fur independent. However, Fur is required for full induction of eap and emp expression in low-iron conditions. In this study, we demonstrated that in addition to Fur, low-iron-induced biofilm formation requires Sae, Agr, and SarA. In iron-restricted growth conditions, Sae and Agr are essential for Emp and Eap expression and hence for biofilm formation, whereas SarA appears to have a less-significant role. We also showed that expression of the ica operon is required for biofilm formation in iron-restricted growth conditions. We demonstrated that in fact, ica is required for the expression of the important multifunctional virulence determinants eap and emp. PMID:18268030

Micromorphologic evidence for paleosol development in the Endicott group, Siksikpuk formation, Kingak(?) shale, and Ipewik formation, western Brooks range, Alaska

USGS Publications Warehouse

Dumoulin, Julie A.; White, Tim

2005-01-01

Micromorphologic evidence indicates the presence of paleosols in drill-core samples from four sedimentary units in the Red Dog area, western Brooks Range. Well-developed sepic-plasmic fabrics and siderite spherules occur in claystones of the Upper Devonian through Lower Mississippian(?) Kanayut Conglomerate (Endicott Group), the Pennsylvanian through Permian Siksikpuk Formation (Etivluk Group), the Jurassic through Lower Cretaceous Kingak(?) Shale, and the Lower Cretaceous Ipewik Formation. Although exposure surfaces have been previously recognized in the Endicott Group and Kingak Shale on the basis of outcrop features, our study is the first microscopic analysis of paleosols from these units, and it provides the first evidence of subaerial exposure in the Siksikpuk and Ipewik Formations. Regional stratigraphic relations and geochemical data support our interpretations. Paleosols in the Siksikpuk, Kingak, and Ipewik Formations likely formed in nearshore coastal-plain environments, with pore waters subjected to inundation by the updip migration of slightly brackish ground water, whereas paleosols in the Kanayut Conglomerate probably formed in a more distal setting relative to a marine basin.

Differential tumor biology effects of double-initiation in a mouse skin chemical carcinogenesis model comparing wild type versus protein kinase Cepsilon overexpression mice.

PubMed

Li, Yafan; Wheeler, Deric L; Ananthaswamy, Honnavara N; Verma, Ajit K; Oberley, Terry D

2007-12-01

Our previous studies showed that protein kinase Cepsilon (PKCepsilon) verexpression in mouse skin resulted in metastatic squamous cell carcinoma (SCC) elicited by single 7,12-dimethylbenz(a)anthracene (DMBA)-initiation and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promotion in the absence of preceding papilloma formation as is typically observed in wild type mice. The present study demonstrates that double-DMBA initiation modulates tumor incidence, multiplicity, and latency period in both wild type and PKCepsilon overexpression transgenic (PKCepsilon-Tg) mice. After 17 weeks (wks) of tumor promotion, a reduction in papilloma multiplicity was observed in double- versus single-DMBA initiated wild type mice. Papilloma multiplicity was inversely correlated with cell death indices of interfollicular keratinocytes, indicating decreased papilloma formation was caused by increased cell death and suggesting the origin of papillomas is in interfollicular epidermis. Double-initiated PKCepsilon-Tg mice had accelerated carcinoma formation and cancer incidence in comparison to single-initiated PKCepsilon-Tg mice. Morphologic analysis of mouse skin following double initiation and tumor promotion showed a similar if not identical series of events to those previously observed following single initiation and tumor promotion: putative preneoplastic cells were observed arising from hyperplastic hair follicles (HFs) with subsequent cancer cell infiltration into the dermis. Single-initiated PKCepsilon-Tg mice exhibited increased mitosis in epidermal cells of HFs during tumor promotion.

Heat capacity changes in carbohydrates and protein-carbohydrate complexes.

PubMed

Chavelas, Eneas A; García-Hernández, Enrique

2009-05-13

Carbohydrates are crucial for living cells, playing myriads of functional roles that range from being structural or energy-storage devices to molecular labels that, through non-covalent interaction with proteins, impart exquisite selectivity in processes such as molecular trafficking and cellular recognition. The molecular bases that govern the recognition between carbohydrates and proteins have not been fully understood yet. In the present study, we have obtained a surface-area-based model for the formation heat capacity of protein-carbohydrate complexes, which includes separate terms for the contributions of the two molecular types. The carbohydrate model, which was calibrated using carbohydrate dissolution data, indicates that the heat capacity contribution of a given group surface depends on its position in the saccharide molecule, a picture that is consistent with previous experimental and theoretical studies showing that the high abundance of hydroxy groups in carbohydrates yields particular solvation properties. This model was used to estimate the carbohydrate's contribution in the formation of a protein-carbohydrate complex, which in turn was used to obtain the heat capacity change associated with the protein's binding site. The model is able to account for protein-carbohydrate complexes that cannot be explained using a previous model that only considered the overall contribution of polar and apolar groups, while allowing a more detailed dissection of the elementary contributions that give rise to the formation heat capacity effects of these adducts.

Post-Training Intrahippocampal Inhibition of Class I Histone Deacetylases Enhances Long-Term Object-Location Memory

ERIC Educational Resources Information Center

Hawk, Joshua D.; Florian, Cedrick; Abel, Ted

2011-01-01

Long-term memory formation involves covalent modification of the histone proteins that package DNA. Reducing histone acetylation by mutating histone acetyltransferases impairs long-term memory, and enhancing histone acetylation by inhibiting histone deacetylases (HDACs) improves long-term memory. Previous studies using HDAC inhibitors to enhance…

Enhancing paper strength by optimizing defect configuration

Treesearch

J.M. Considine; W. Skye; W. Chen; D. Matthys; David W. Vahey; K. Turner; R. Rowlands

2009-01-01

Poor formation in paper, as denoted by large local variation of mass, tends to reduce maximum tensile strength but has not been well characterized. The effect of grammage variation on tensile strength was studied by introducing carefully placed holes in tensile specimens made of three different paper materials. Previous researchers demonstrated that the point-stress...

Antecedents of Identity Development in a Structured Recreation Setting: A Qualitative Inquiry

ERIC Educational Resources Information Center

Duerden, Mat D.; Taniguchi, Stacy; Widmer, Mark

2012-01-01

Identity research has focused primarily on outcomes associated with identity formation. Far less attention, however, has been given to understanding the facilitating contextual elements of this process. This qualitative study examined a context, a 2-week adventure recreation program for youth, quantitatively shown in previous research to have…

Kindergarten and Primary School Children's Everyday, Synthetic, and Scientific Concepts of Clouds and Rainfall

ERIC Educational Resources Information Center

Malleus, Elina; Kikas, Eve; Marken, Tiivi

2017-01-01

The purpose of this research was to explore children's understandings of everyday, synthetic and scientific concepts to enable a description of how abstract, verbally taught material relates to previous experience-based knowledge and the consistency of understanding about cloud formation. This study examined the conceptual understandings of cloud…

NEURONS COMPRISING A HETEROTOPIA INDUCED BY DEVELOPMENTAL HYPOTHYROIDISM ARE BORN LATE IN GESTATION.

EPA Science Inventory

We previously described an abnormal cluster of neurons, a heterotopia, located in the corpus callosum in rat pups born to dams exposed to the goitrogen, propylthiouracil (PTU, Goodman et al., SfN 2004). In this study we determined 1) whether the formation of the heterotopia was u...

Rethinking the Education/State Formation Connection: Pedagogic Reform in Singapore, 1945-1965.

ERIC Educational Resources Information Center

Wong, Ting-Hong; Apple, Michael

2002-01-01

Previous studies of the role of education in state-building have neglected the relative autonomy and non-neutral stance of the school system. Bernstein's notion of "pedagogic device" is used to illuminate conflicts and contradictions between educational development and state-building in the case of Singapore's efforts to control the…

Parallel Consolidation of Simple Features into Visual Short-Term Memory

ERIC Educational Resources Information Center

Mance, Irida; Becker, Mark W.; Liu, Taosheng

2012-01-01

Although considerable research has examined the storage limits of visual short-term memory (VSTM), little is known about the initial formation (i.e., the consolidation) of VSTM representations. A few previous studies have estimated the capacity of consolidation to be one item at a time. Here we used a sequential-simultaneous manipulation to…

The Role of Communication and Cohesion in Reducing Social Loafing in Group Projects

ERIC Educational Resources Information Center

Lam, Chris

2015-01-01

This study examines previously untested variables that influence social loafing in professional and technical communication group projects by determining the influence of communication quality and task cohesion on social loafing. A set-up factors model, which included group size, peer review, project scope, and method of team formation, was also…

Conjugative type IVb pilus recognizes lipopolysaccharide of recipient cells to initiate PAPI-1 pathogenicity island transfer in Pseudomonas aeruginosa

USDA-ARS?s Scientific Manuscript database

Pseudomonas aeruginosa pathogenicity island 1 (PAPI-1) is one of the largest genomic islands of this important opportunistic human pathogen. Previous studies have shown that PAPI-1 encodes several putative virulence factors, a major regulator of biofilm formation, and antibiotic-resistance traits, a...

Introducing the Objective Structured Clinical Examination (OSCE) in the Undergraduate Psychiatric Curriculum: Evaluation after One Year

ERIC Educational Resources Information Center

Zahid, Muhammad Ajmal; Al-Zayed, Adel; Ohaeri, Jude; Varghese, Ramani

2011-01-01

Objective: The Objective Structured Clinical Examination (OSCE) was introduced in undergraduate psychiatry clerkship in 2008. The authors studied the effect of OSCE on the students' performance. Methods: The "short case" (SC) and "oral examination" (OE), two of the five components of the previous assessment format, were…

Norepinephrine Triggers Metaplasticity of LTP by Increasing Translation of Specific mRNAs

ERIC Educational Resources Information Center

Maity, Sabyasachi; Rah, Sean; Sonenberg, Nahum; Gkogkas, Christos G.; Nguyen, Peter V.

2015-01-01

Norepinephrine (NE) is a key modulator of synaptic plasticity in the hippocampus, a brain structure crucially involved in memory formation. NE boosts synaptic plasticity mostly through initiation of signaling cascades downstream from beta (ß)-adrenergic receptors (ß-ARs). Previous studies demonstrated that a ß-adrenergic receptor agonist,…

Periodic Methods for Controlling a Satellite in Formation

DTIC Science & Technology

2002-03-01

5 5. Clohessy - Wiltshire Reference Frame................................................................... 10 6...techniques to study relative position errors within a satellite cluster [19, 24]. The dynamics were based on Clohessy - Wiltshire equations with near...dynamics model by solving the time periodic, linearized system using Floquet Theory. More accurate than the Clohessy - Wiltshire solutions used in previous

Specialization in the Human Brain: The Case of Numbers

PubMed Central

Kadosh, Roi Cohen; Bahrami, Bahador; Walsh, Vincent; Butterworth, Brian; Popescu, Tudor; Price, Cathy J.

2011-01-01

How numerical representation is encoded in the adult human brain is important for a basic understanding of human brain organization, its typical and atypical development, its evolutionary precursors, cognitive architectures, education, and rehabilitation. Previous studies have shown that numerical processing activates the same intraparietal regions irrespective of the presentation format (e.g., symbolic digits or non-symbolic dot arrays). This has led to claims that there is a single format-independent, numerical representation. In the current study we used a functional magnetic resonance adaptation paradigm, and effective connectivity analysis to re-examine whether numerical processing in the intraparietal sulci is dependent or independent on the format of the stimuli. We obtained two novel results. First, the whole brain analysis revealed that format change (e.g., from dots to digits), in the absence of a change in magnitude, activated the same intraparietal regions as magnitude change, but to a greater degree. Second, using dynamic causal modeling as a tool to disentangle neuronal specialization across regions that are commonly activated, we found that the connectivity between the left and right intraparietal sulci is format-dependent. Together, this line of results supports the idea that numerical representation is subserved by multiple mechanisms within the same parietal regions. PMID:21808615

Isotope-labeling studies on the formation pathway of acrolein during heat processing of oils.

PubMed

Ewert, Alice; Granvogl, Michael; Schieberle, Peter

2014-08-20

Acrolein (2-propenal) is classified as a foodborne toxicant and was shown to be present in significant amounts in heated edible oils. Up to now, its formation was mainly suggested to be from the glycerol part of triacylglycerides, although a clear influence of the unsaturation of the fatty acid moiety was also obvious in previous studies. To unequivocally clarify the role of the glycerol and the fatty acid parts in acrolein formation, two series of labeled triacylglycerides were synthesized: [(13)C(3)]-triacylglycerides of stearic, oleic, linoleic, and linolenic acid and [(13)C(54)]-triacylglycerides with labeled stearic, oleic, and linoleic acid, but with unlabeled glycerol. Heating of each of the seven intermediates singly in silicon oil and measurement of the formed amounts of labeled and unlabeled acrolein clearly proved the fatty acid backbone as the key precursor structure. Enzymatically synthesized pure linoleic acid and linolenic acid hydroperoxides were shown to be the key intermediates in acrolein formation, thus allowing the discussion of a radical-induced reaction pathway leading to the formation of the aldehyde. Surprisingly, although several oils contained high amounts of acrolein after heating, deep-fried foods themselves, such as donuts or French fries, were low in the aldehyde.

Glyoxal-methylglyoxal cross-reactions in secondary organic aerosol formation.

PubMed

Schwier, Allison N; Sareen, Neha; Mitroo, Dhruv; Shapiro, Erica L; McNeill, V Faye

2010-08-15

Glyoxal (G) and methylglyoxal (MG) are potentially important secondary organic aerosol (SOA) precursors. Previous studies of SOA formation by G and MG have focused on either species separately; however, G and MG typically coexist in the atmosphere. We studied the formation of secondary organic material in aqueous aerosol mimic mixtures containing G and MG with ammonium sulfate. We characterized the formation of light-absorbing products using UV-vis spectrophotometry. We found that absorption at 280 nm can be described well using models for the formation of light-absorbing products by G and MG in parallel. Pendant drop tensiometry measurements showed that surface tension depression by G and MG in these solutions can be modeled as a linear combination of the effects of G and MG alone. Product species were identified using chemical ionization mass spectrometry with a volatilization flow tube inlet (Aerosol CIMS). Peaks consistent with G-MG cross-reaction products were observed, accounting for a significant fraction of detected product mass, but most peaks could be attributed to self-reaction. We conclude that cross-reactions contribute to SOA mass from uptake of G and MG, but they are not required to accurately model the effects of this process on aerosol surface tension or light absorption.

The influence of relational formative discourse on students' positional identities in a middle school science classroom

NASA Astrophysics Data System (ADS)

Trauth-Nare, Amy

Formative assessment is the process of eliciting students' understanding during instruction in order to make sensitive instructional decisions and provide feedback to enhance students' learning. Research indicates that when used properly, formative assessment can lead to significant learning gains and enhance students' self-efficacy. Drawing on previous research and a framework of relational pedagogy, I studied the positional identities claimed, assigned and negotiated by a middle school science teacher and her students during formative assessment interactions. Critical discourse analysis was used to analyze classroom interactions, teacher debriefings and student interviews. Findings from this study indicated that the teacher normatively positioned herself as authority during formative assessment interactions, yet students were not completely powerless. Through assertions of content knowledge and re-directions of topical focus, students positioned themselves actively and had the capacity to influence the direction and focus of formative assessment. Outside of classroom instruction, the teacher simultaneously positioned herself as both hindered by institutional structures yet actively subverted those structures in both covert and overt ways in the service of meaningful science learning. As indicated from interviews and SPAQ questionnaire responses, many students in this classroom positioned themselves positively in relation to science, the teacher and her methods of assessment, while some felt marginalized. This research has implications for the ways in which formative assessment is used to support teaching and learning in science classrooms. Findings from this study indicate that formative assessment is not simply an instrumental act carried out by teachers, but rather is a relational process that necessarily involves students. As a result, formative assessment should balance authoritative and dialogic discourse as a means for supporting and engaging students as they develop rich conceptions of science while connecting those conceptions to their own experiences.

N-nitrosodimethylamine (NDMA) formation from the ozonation of model compounds.

PubMed

Marti, Erica J; Pisarenko, Aleksey N; Peller, Julie R; Dickenson, Eric R V

2015-04-01

Nitrosamines are a class of toxic disinfection byproducts commonly associated with chloramination, of which several were included on the most recent U.S. EPA Contaminant Candidate List. Nitrosamine formation may be a significant barrier to ozonation in water reuse applications, particularly for direct or indirect potable reuse, since recent studies show direct formation during ozonation of natural water and treated wastewaters. Only a few studies have identified precursors which react with ozone to form N-nitrosodimethylamine (NDMA). In this study, several precursor compound solutions, prepared in ultrapure water and treated wastewater, were subjected to a 10 M excess of ozone. In parallel experiments, the precursor solutions in ultrapure water were exposed to gamma radiation to determine NDMA formation as a byproduct of reactions of precursor compounds with hydroxyl radicals. The results show six new NDMA precursor compounds that have not been previously reported in the literature, including compounds with hydrazone and carbamate moieties. Molar yields in deionized water were 61-78% for 3 precursors, 12-23% for 5 precursors and <4% for 2 precursors. Bromide concentration was important for three compounds (1,1-dimethylhydrazine, acetone dimethylhydrazone and dimethylsulfamide), but did not enhance NDMA formation for the other precursors. NDMA formation due to chloramination was minimal compared to formation due to ozonation, suggesting distinct groups of precursor compounds for these two oxidants. Hydroxyl radical reactions with the precursors will produce NDMA, but formation is much greater in the presence of molecular ozone. Also, hydroxyl radical scavenging during ozonation leads to increased NDMA formation. Molar conversion yields were higher for several precursors in wastewater as compared to deionized water, which could be due to catalyzed reactions with constituents found in wastewater or hydroxyl radical scavenging. Copyright © 2014 Elsevier Ltd. All rights reserved.

Localization of sarcomeric proteins during myofibril assembly in cultured mouse primary skeletal myotubes

PubMed Central

White, Jennifer; Barro, Marietta V.; Makarenkova, Helen P.; Sanger, Joseph W.; Sanger, Jean M.

2014-01-01

It is important to understand how muscle forms normally in order to understand muscle diseases that result in abnormal muscle formation. Although the structure of myofibrils is well understood, the process through which the myofibril components form organized contractile units is not clear. Based on the staining of muscle proteins in avian embryonic cardiomyocytes, we previously proposed that myofibrils formation occurred in steps that began with premyofibrils followed by nascent myofibrils and ending with mature myofibrils. The purpose of this study was to determine whether the premyofibril model of myofibrillogenesis developed from studies developed from studies in avian cardiomyocytes was supported by our current studies of myofibril assembly in mouse skeletal muscle. Emphasis was on establishing how the key sarcomeric proteins, F-actin, non-muscle myosin II, muscle myosin II, and α-actinin were organized in the three stages of myofibril assembly. The results also test previous reports that non-muscle myosins II A and B are components of the Z-Bands of mature myofibrils, data that are inconsistent with the premyofibril model. We have also determined that in mouse muscle cells, telethonin is a late assembling protein that is present only in the Z-Bands of mature myofibrils. This result of using specific telethonin antibodies supports the approach of using YFP-tagged proteins to determine where and when these YFP-sarcomeric fusion proteins are localized. The data presented in this study on cultures of primary mouse skeletal myocytes are consistent with the premyofibril model of myofibrillogenesis previously proposed for both avian cardiac and skeletal muscle cells. PMID:25125171

Do supercontinents introvert or extrovert?: Sm-Nd isotope evidence

NASA Astrophysics Data System (ADS)

Brendan Murphy, J.; Damian Nance, R.

2003-10-01

In recent years, two end-member models for the formation of supercontinents have emerged. In the classical Wilson cycle, oceanic crust generated during supercontinent breakup (the interior ocean) is consumed during subsequent amalgamation so that the supercontinent turns “inside in” (introversion). Alternatively, following supercontinent breakup, the exterior margins of the dispersing continental fragments collide during reassembly so that the supercontinent turns “outside in” (extroversion). These end-member models can be distinguished by comparing the Sm-Nd crust-formation ages of accreted mafic complexes (e.g., ophiolites) in the collisional orogens formed during supercontinent assembly with the breakup age of the previous supercontinent. For supercontinents generated by introversion, these crust-formation ages postdate rifting of the previous supercontinent. For supercontinents generated by extroversion, the oceanic lithosphere consumed during reassembly predates breakup of the previous supercontinent, so that crust-formation ages of accreted mafic complexes are older than the age of rifting. In the Paleozoic Appalachian-Caledonide-Variscan orogen, a key collisional orogen in the assembly of Pangea, crust-formation ages of accretionary mafic complexes postdate the formation of the Iapetus Ocean (i.e., are younger than ca. 0.6 Ga), suggesting supercontinent reassembly by introversion. By contrast, the Neoproterozoic East African and Brasiliano orogens, which formed during the amalgamation of Gondwana, are characterized by mafic complexes with crust-formation ages (ca. 0.75 1.2 Ga) that predate the ca. 750 Ma breakup of Rodinia. Hence, these complexes must have formed from lithosphere in the exterior ocean that surrounded Rodinia, implying that this ocean was consumed during the amalgamation of Gondwana. These data indicate that Pangea and Gondwana were formed by introversion and extroversion, respectively, implying that supercontinents can be assembled by fundamentally distinct geodynamic processes.

Predicting Success for Nontraditional Students in an Afternoon and Evening/Weekend Associate Degree in Nursing Program

ERIC Educational Resources Information Center

Ledesma, Hernani Luison, Jr.

2012-01-01

Mount St. Mary's College has offered a nontraditional Associate Degree in Nursing (ADN) Program since 1992. The program has an afternoon and evening/weekend format. There has been one previous research study published in 2005 that described the student population that Mount St. Mary's College serves. This present study will examine the…

EXPERIMENTAL STUDY ON THE EFFECT OF SO2 ON PCDD/F EMISSIONS: DETERMINATION OF THE IMPORTANCE OF GAS-PHASE VERSUS SOLID-PHASE REACTIONS IN PCDD/F FORMATION

EPA Science Inventory

Co-firing coal in municipal solid waste incinerators (MSWIs) has previously been reported to reduce PCDD/F emissions due to increasing the flue gas SO₂ concentration due to the fossil fuel addition. The present study was focused on understanding the mechanism predomina...

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

Amaro, Mariana; Wellbrock, Thorben; Birch, David J. S.

The fluorescence decay of beta-amyloid's (Aβ) intrinsic fluorophore tyrosine has been used for sensing the oligomer formation of dye-labelled Aβ monomers and the results compared with previously studied oligomerization of the non-labelled Aβ peptides. It has been demonstrated that two different sized, covalently bound probes 7-diethylaminocoumarin-3-carbonyl and Hilyte Fluor 488 (HLF), alter the rate and character of oligomerization to different extents. The ability of HLF to inhibit formation of highly ordered structures containing beta-sheets was also shown. The implications of our findings for using fluorescence methods in amyloidosis research are discussed and the advantages of this auto-fluorescence approach highlighted.

Accelerated Implantable Defibrillator Battery Depletion Secondary to Lithium Cluster Formation: A Case Series.

PubMed

Aggarwal, Ashim; Sarmiento, Joseph J; Charles, David R; Parr, Alan R; Baman, Timir S

2016-04-01

Device failure from unanticipated and precipitous battery depletion is uncommon but can be life-threatening. Multiple mechanisms of battery failure have been previously described in the medical literature. However, in this current case series, we describe the largest cohort of patients (n = 4) with St. Jude (St. Paul, MN, USA) early implantable defibrillator battery depletion attributable to lithium cluster formation causing short circuit and high current drain. Clinicians must be aware of this occult cause of device failure and more studies are needed to determine its true prevalence. © 2015 Wiley Periodicals, Inc.

Studies of Brazilian meteorites. XIII - Mineralogy, petrology, and chemistry of the Putinga, Rio Grande do Sul, chondrite

NASA Technical Reports Server (NTRS)

Keil, K.; Lange, D.; Ulbrich, M. N. C.; Gomes, C. B.; Jarosewich, E.; Roisenberg, A.; Souza, M. J.

1978-01-01

The Putinga, Rio Grande do Sul chondrite is described and classified as an L6. The mineral composition and some significant ratios of elements are reported, and the reasons for assignment to the L group and to petrologic type 6 are explained. The analysis suggests that maskelynite of oligoclase composition was formed by solid-state shock transformation of previously existing well-crystallized plagioclase at estimated shock pressures of about 250-350 kbar. This finding indicates that recrystallization (formation of well-crystallized oligoclase) preceded shock transformation formation of the maskelynite.

The functional properties of chitosan-glucose-asparagine Maillard reaction products and mitigation of acrylamide formation by chitosans.

PubMed

Sung, Wen-Chieh; Chang, Yu-Wei; Chou, Yu-Hao; Hsiao, Hsin-I

2018-03-15

This research aims to clarify the interactions that occur in a food model system consisting of glucose, asparagine and chitosans. Low molecular weight chitosan exerted a potent inhibitory effect (46.8%) on acrylamide and Maillard reaction products (MRPs) (>52.6%), respectively. Compared to a previous study conducted using the fructose system, the novel findings of this research demonstrate that the formation of acrylamide and Maillard reaction products was lower with glucose than with fructose when they were used as reducing sugars in food model systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Satellite servicing economic study

NASA Technical Reports Server (NTRS)

1990-01-01

Previous studies have shown that satellite servicing is cost effective; however, all of these studies were of different formats, dollar year, learning rates, availability, etc. Therefore, it was difficult to correlate any useful trends from these studies. The reviewed study was initiated to correlate the economic data into a common data base, using a common set of assumptions. A selected set of existed funded programs was then analyzed to provide an independent analysis of the servicing options and potential economic benefits.

Satellite servicing economic study

NASA Technical Reports Server (NTRS)

1990-01-01

Previous studies have shown that satellite servicing is cost effective; however, all of these studies were of different formats, dollar year, learning rates, availability, etc. Threfore, it was difficult to correlate any useful trends from these studies. The reviewed study was initiated to correlate the economic data into a common data base, using a common set of assumptions. A selected set of existed funded programs was then analyzed to provide an independent analysis of the servicing options and potential economic benefits.

Incremental Reactivity Effects on Secondary Organic Aerosol Formation in Urban Atmospheres with and without Biogenic Influence

NASA Astrophysics Data System (ADS)

Kacarab, Mary; Li, Lijie; Carter, William P. L.; Cocker, David R., III

2016-04-01

Two different surrogate mixtures of anthropogenic and biogenic volatile organic compounds (VOCs) were developed to study secondary organic aerosol (SOA) formation at atmospheric reactivities similar to urban regions with varying biogenic influence levels. Environmental chamber simulations were designed to enable the study of the incremental aerosol formation from select anthropogenic (m-Xylene, 1,2,4-Trimethylbenzene, and 1-Methylnaphthalene) and biogenic (α-pinene) precursors under the chemical reactivity set by the two different surrogate mixtures. The surrogate reactive organic gas (ROG) mixtures were based on that used to develop the maximum incremental reactivity (MIR) factors for evaluation of O3 forming potential. Multiple incremental aerosol formation experiments were performed in the University of California Riverside (UCR) College of Engineering Center for Environmental Research and Technology (CE-CERT) dual 90m3 environmental chambers. Incremental aerosol yields were determined for each of the VOCs studied and compared to yields found from single precursor studies. Aerosol physical properties of density, volatility, and hygroscopicity were monitored throughout experiments. Bulk elemental chemical composition from high-resolution time of flight aerosol mass spectrometer (HR-ToF-AMS) data will also be presented. Incremental yields and SOA chemical and physical characteristics will be compared with data from previous single VOC studies conducted for these aerosol precursors following traditional VOC/NOx chamber experiments. Evaluation of the incremental effects of VOCs on SOA formation and properties are paramount in evaluating how to best extrapolate environmental chamber observations to the ambient atmosphere and provides useful insights into current SOA formation models. Further, the comparison of incremental SOA from VOCs in varying surrogate urban atmospheres (with and without strong biogenic influence) allows for a unique perspective on the impacts different compounds have on aerosol formation in different urban regions.

Formative Self-Assessment College Classes Improves Self-Regulation and Retention in First/Second Year Community College Students

ERIC Educational Resources Information Center

Mahlberg, Jamie

2015-01-01

This research examined the influence formative self-assessment had on first/second year community college student self-regulatory practices. Previous research has shown that the ability to regulate one's learning activities can improve performance in college classes, and it has long been known that the use of formative assessment improves…

Prophages and Growth Dynamics Confound Experimental Results with Antibiotic-Tolerant Persister Cells

PubMed Central

Fino, Cinzia; Sørensen, Michael A.; Semsey, Szabolcs

2017-01-01

ABSTRACT Bacterial persisters are phenotypic variants that survive antibiotic treatment in a dormant state and can be formed by multiple pathways. We recently proposed that the second messenger (p)ppGpp drives Escherichia coli persister formation through protease Lon and activation of toxin-antitoxin (TA) modules. This model found considerable support among researchers studying persisters but also generated controversy as part of recent debates in the field. In this study, we therefore used our previous work as a model to critically examine common experimental procedures to understand and overcome the inconsistencies often observed between results of different laboratories. Our results show that seemingly simple antibiotic killing assays are very sensitive to variations in culture conditions and bacterial growth phase. Additionally, we found that some assay conditions cause the killing of antibiotic-tolerant persisters via induction of cryptic prophages. Similarly, the inadvertent infection of mutant strains with bacteriophage ϕ80, a notorious laboratory contaminant, apparently caused several of the phenotypes that we reported in our previous studies. We therefore reconstructed all infected mutants and probed the validity of our model of persister formation in a refined assay setup that uses robust culture conditions and unravels the dynamics of persister cells through all bacterial growth stages. Our results confirm the importance of (p)ppGpp and Lon but no longer support a role of TA modules in E. coli persister formation under unstressed conditions. We anticipate that the results and approaches reported in our study will lay the ground for future work in the field. PMID:29233898

Secondary organic aerosol formation from photochemical aging of light-duty gasoline vehicle exhausts in a smog chamber

NASA Astrophysics Data System (ADS)

Liu, T.; Wang, X.; Deng, W.; Hu, Q.; Ding, X.; Zhang, Y.; He, Q.; Zhang, Z.; Lü, S.; Bi, X.; Chen, J.; Yu, J.

2015-08-01

In China, a rapid increase in passenger vehicles has led to the growing concern of vehicle exhaust as an important source of anthropogenic secondary organic aerosol (SOA) in megacities hard hit by haze. In this study, the SOA formation of emissions from two idling light-duty gasoline vehicles (LDGVs) (Euro 1 and Euro 4) operated in China was investigated in a 30 m3 smog chamber. Five photo-oxidation experiments were carried out at 25 °C with relative humidity at around 50 %. After aging at an OH exposure of 5 × 106 molecules cm-3 h, the formed SOA was 12-259 times as high as primary organic aerosol (POA). The SOA production factors (PF) were 0.001-0.044 g kg-1 fuel, comparable with those from the previous studies at comparable OH exposure. This quite lower OH exposure than that in typical atmospheric conditions might however lead to the underestimation of the SOA formation potential from LDGVs. Effective SOA yields in this study were well fit by a one-product gas-particle partitioning model but quite lower than those of a previous study investigating SOA formation from three idling passenger vehicles (Euro 2-4). Traditional single-ring aromatic precursors and naphthalene could explain 51-90 % of the formed SOA. Unspeciated species such as branched and cyclic alkanes might be the possible precursors for the unexplained SOA. A high-resolution time-of-flight aerosol mass spectrometer was used to characterize the chemical composition of SOA. The relationship between f43 (ratio of m/z 43, mostly C2H3O+, to the total signal in mass spectrum) and f44 (mostly CO2+) of the gasoline vehicle exhaust SOA is similar to the ambient semi-volatile oxygenated organic aerosol (SV-OOA). We plot the O : C and H : C molar ratios of SOA in a Van Krevelen diagram. The slopes of ΔH : C / ΔO : C ranged from -0.59 to -0.36, suggesting that the oxidation chemistry in these experiments was a combination of carboxylic acid and alcohol/peroxide formation.

On the Numerical Study of Heavy Rainfall in Taiwan

NASA Technical Reports Server (NTRS)

Tao, Wei-Kuo; Chen, Ching-Sen; Chen, Yi-Leng; Jou, Ben Jong-Dao; Lin, Pay-Liam; Starr, David OC. (Technical Monitor)

2001-01-01

Heavy rainfall events are frequently observed over the western side of the CMR (central mountain range), which runs through Taiwan in a north-south orientation, in a southwesterly flow regime and over the northeastern side of the CMR in a northeasterly flow regime. Previous studies have revealed the mechanisms by which the heavy rainfall events are formed. Some of them have examined characteristics of the heavy rainfall via numerical simulations. In this paper, some of the previous numerical studies on heavy rainfall events around Taiwan during the Mei-Yu season (May and June), summer (non-typhoon cases) and autumn will be reviewed. Associated mechanisms proposed from observational studies will be reviewed first, and then characteristics of numerically simulated heavy rainfall events will be presented. The formation mechanisms of heavy rainfall from simulated results and from observational analysis are then compared and discussed. Based on these previous modeling studies, we will also discuss what are the major observations and modeling processes which will be needed for understanding the heavy precipitation in the future.

Star Formation Rates in Cooling Flow Clusters: A UV Pilot Study with Archival XMM-Newton Optical Monitor Data

NASA Technical Reports Server (NTRS)

Hicks, A. K.; Mushotzky, R.

2006-01-01

We have analyzed XMM-Newton Optical Monitor (OM) UV (180-400 nm) data for a sample of 33 galaxies. 30 are cluster member galaxies, and nine of these are central cluster galaxies (CCGs) in cooling flow clusters having mass deposition rates which span a range of 8 - 525 Solar Mass/yr. By comparing the ratio of UV to 2MASS J band fluxes, we find a significant UV excess in many, but not all, cooling flow CCGs, a finding consistent with the outcome of previous studies based on optical imaging data (McNamara & O'Connell 1989; Cardiel, Gorgas, & Aragon-Salamanca 1998; Crawford et al. 1999). This UV excess is a direct indication of the presence of young massive stars, and therefore recent star formation, in these galaxies. Using the Starburst99 spectral energy distribution (SED) model of continuous star formation over a 900 Myr period, we derive star formation rates of 0.2 - 219 solar Mass/yr for the cooling flow sample. For 2/3 of this sample it is possible to equate Chandra/XMM cooling flow mass deposition rates with UV inferred star formation rates, for a combination of starburst lifetime and IMF slope. This is a pilot study of the well populated XMM UV cluster archive and a more extensive follow up study is currently underway.

Trifluoperazine Regulation of Calmodulin Binding to Fas: A Computational Study

PubMed Central

Pan, Di; Yan, Qi; Chen, Yabing; McDonald, Jay M; Song, Yuhua

2011-01-01

Death-inducing signaling complex (DISC) formation is a critical step in Fas-mediated signaling for apoptosis. Previous experiments have demonstrated that the calmodulin (CaM) antagonist, trifluoperazine (TFP) regulates CaM-Fas binding and affects Fas-mediated DISC formation. In this study, we investigated the anti-cooperative characteristics of TFP binding to CaM and the effect of TFP on the CaM-Fas interaction from both structural and thermodynamic perspectives using combined molecular dynamics simulations and binding free energy analyses. We studied the interactions of different numbers of TFP molecules with CaM and explored the effects of the resulting conformational changes in CaM on CaM-Fas binding. Results from these analyses showed that the number of TFP molecules bound to CaM directly influenced α-helix formation and hydrogen bond occupancy within the α-helices of CaM, contributing to the conformational and motion changes in CaM. These changes affected CaM binding to Fas, resulting in secondary structural changes in Fas and conformational and motion changes of Fas in CaM-Fas complexes, potentially perturbing the recruitment of Fas-associated death domain (FADD) for DISC formation. The computational results from this study reveal the structural and molecular mechanisms that underlie the role of the CaM antagonist, TFP, in regulation of CaM-Fas binding and Fas-mediated DISC formation in a concentration-dependent manner. PMID:21656570

Extrasynaptic GABAA receptors in rat pontine reticular formation increase wakefulness.

PubMed

Vanini, Giancarlo; Baghdoyan, Helen A

2013-03-01

Gamma-aminobutyric acid (GABA) causes phasic inhibition via synaptic GABAA receptors and tonic inhibition via extrasynaptic GABAA receptors. GABA levels in the extracellular space regulate arousal state and cognition by volume transmission via extrasynaptic GABAA receptors. GABAergic transmission in the pontine reticular formation promotes wakefulness. No previous studies have determined whether an agonist at extrasynaptic GABAA receptors administered into the pontine reticular formation alters sleep and wakefulness. Therefore, this study used gaboxadol (THIP; agonist at extrasynaptic GABAA receptors that contain a δ subunit) to test the hypothesis that extrasynaptic GABAA receptors within the pontine reticular formation modulate sleep and wakefulness. Within/between subjects. University of Michigan. Adult male Crl:CD*(SD) (Sprague-Dawley) rats (n = 10). Microinjection of gaboxadol, the nonsubtype selective GABAA receptor agonist muscimol (positive control), and saline (negative control) into the rostral pontine reticular formation. Gaboxadol significantly increased wakefulness and decreased both nonrapid eye movement sleep and rapid eye movement sleep in a concentration-dependent manner. Relative to saline, gaboxadol did not alter electroencephalogram power. Microinjection of muscimol into the pontine reticular formation of the same rats that received gaboxadol increased wakefulness and decreased sleep. Tonic inhibition via extrasynaptic GABAA receptors that contain a δ subunit may be one mechanism by which the extracellular pool of endogenous GABA in the rostral pontine reticular formation promotes wakefulness. Vanini G; Baghdoyan HA. Extrasynaptic GABAA receptors in rat pontine reticular formation increase wakefulness. SLEEP 2013;36(3):337-343.

Rotational spectrum of 13C{2}-methyl formate (HCOO13CH{3}) and detection of the two 13C-methyl formate in Orion

NASA Astrophysics Data System (ADS)

Carvajal, M.; Margulès, L.; Tercero, B.; Demyk, K.; Kleiner, I.; Guillemin, J. C.; Lattanzi, V.; Walters, A.; Demaison, J.; Wlodarczak, G.; Huet, T. R.; Møllendal, H.; Ilyushin, V. V.; Cernicharo, J.

2009-06-01

Context: Laboratory measurements and analysis of the microwave and millimeter-wave spectra of potential interstellar molecules are a prerequisite for their subsequent identification by radioastronomical techniques. The spectral analysis provides spectroscopic parameters that are used in the assignment procedure of the laboratory spectra, and that also predict the frequencies of transitions not measured in the laboratory with a high degree of precision. Aims: An experimental laboratory study and its theoretical analysis is presented for 13C2-methyl formate (HCOO13CH3) allowing a search for this isotopologue in the Orion molecular cloud. The 13C1-methyl formate (H13COOCH3) molecule was also searched for in this interstellar cloud, using previously published spectroscopic data. Methods: The experimental spectra of 13C2-methyl formate were recorded in the microwave and sub-mm energy ranges (4-20 GHz, 8-80 GHz, 150-700 GHz). The spectra were analyzed using the Rho-Axis Method (RAM), which takes the CH3 internal rotation and the coupling between internal rotation and global rotation into account. Results: Twenty-seven spectroscopic constants of 13C2-methyl formate have been obtained from a fit of 936 transitions of the ground torsional state with a standard (unitless) deviation of 1.08. A prediction of line positions and intensities is also produced. This prediction allowed us to identify 230 13C2-methyl formate lines in the Orion interstellar molecular cloud. We refitted all previously published ground state transitions of the 13C1-methyl formate molecule in order to provide a prediction of its ground state spectrum. 234 lines of 13C1-methyl formate were detected in the Orion interstellar cloud using that prediction. Tables A.1-A.5 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/500/1109

The dual-basin landscape in GFP folding

PubMed Central

Andrews, Benjamin T.; Gosavi, Shachi; Finke, John M.; Onuchic, José N.; Jennings, Patricia A.

2008-01-01

Recent experimental studies suggest that the mature GFP has an unconventional landscape composed of an early folding event with a typical funneled landscape, followed by a very slow search and rearrangement step into the locked, active chromophore-containing structure. As we have shown previously, the substantial difference in time scales is what generates the observed hysteresis in thermodynamic folding. The interconversion between locked and the soft folding structures at intermediate denaturant concentrations is so slow that it is not observed under the typical experimental observation time. Simulations of a coarse-grained model were used to describe the fast folding event as well as identify native-like intermediates on energy landscapes enroute to the fluorescent native fold. Interestingly, these simulations reveal structural features of the slow dynamic transition to chromophore activation. Experimental evidence presented here shows that the trapped, native-like intermediate has structural heterogeneity in residues previously linked to chromophore formation. We propose that the final step of GFP folding is a “locking” mechanism leading to chromophore formation and high stability. The combination of previous experimental work and current simulation work is explained in the context of a dual-basin folding mechanism described above. PMID:18713871

Revisions to the stratigraphic nomenclature of the Abiquiu Formation, Abiquiu and contiguous areas, north-central New Mexico

USGS Publications Warehouse

Maldonado, Florian; Kelley, Shari A.

2009-01-01

Stratigraphic studies and geologic mapping on the Abiquiu 7.5-min quadrangle have led to revision of the stratigraphic nomenclature for the Oligocene to Miocene Abiquiu Formation in north-central New Mexico. The Abiquiu Formation had previously been defined to include informal upper, middle (Pedernal chert member), and lower members. The basement-derived conglomeratic lower member in the northern Jemez Mountains and Abiquiu embayment is here redefined. We propose removing the "lower member" from the Abiquiu Formation because provenance of these coarse sediments is dramatically different than the volcaniclastic strata of the "upper member." Furthermore, we propose that the term "lower member of the Abiquiu Formation" be replaced with an existing unit name, the Ritito Conglomerate of Barker (1958), and that the name Abiquiu Formation be restricted to the volcaniclastic succession. The lower part of the Ritito Conglomerate in Arroyo del Cobre on the Abiquiu quadrangle is 47 m (155 ft) thick and is composed of arkosic conglomeratic beds interbedded with arkosic sands and siltstones. Clasts include, in descending order of abundance, Proterozoic quartzite, granite, metavolcanic rocks, quartz, schist, and gneiss and a trace of Mesozoic sandstone and Paleozoic chert. Clasts are predominantly of pebble and cobble size but range from granule to boulder size. Paleocurrent data collected in the Arroyo del Cobre area indicate that the Ritito Conglomerate was deposited by a south-flowing river system during the Oligocene, eroding Laramide highlands such as the Tusas Mountains to the northeast, which contain predominantly Proterozoic rocks. This depositional setting has also been suggested by previous workers. The middle member or Pedernal chert member is present both at the top of the Ritito Conglomerate and as lenses within the lower part of the Abiquiu Formation. This post-depositional diagenetic chert remains an informal unit called the Pedernal chert.

Scheduling double round-robin tournaments with divisional play using constraint programming

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

Carlsson, Mats; Johansson, Mikael; Larson, Jeffrey

We study a tournament format that extends a traditional double round-robin format with divisional single round-robin tournaments. Elitserien, the top Swedish handball league, uses such a format for its league schedule. We present a constraint programming model that characterizes the general double round-robin plus divisional single round-robin format. This integrated model allows scheduling to be performed in a single step, as opposed to common multistep approaches that decompose scheduling into smaller problems and possibly miss optimal solutions. In addition to general constraints, we introduce Elitserien-specific requirements for its tournament. These general and league-specific constraints allow us to identify implicit andmore » symmetry-breaking properties that reduce the time to solution from hours to seconds. A scalability study of the number of teams shows that our approach is reasonably fast for even larger league sizes. The experimental evaluation of the integrated approach takes considerably less computational effort to schedule Elitserien than does the previous decomposed approach. (C) 2016 Elsevier B.V. All rights reserved« less

Carnosine's Effect on Amyloid Fibril Formation and Induced Cytotoxicity of Lysozyme

PubMed Central

Wu, Josephine W.; Liu, Kuan-Nan; How, Su-Chun; Chen, Wei-An; Lai, Chia-Min; Liu, Hwai-Shen; Hu, Chaur-Jong; Wang, Steven S. -S.

2013-01-01

Carnosine, a common dipeptide in mammals, has previously been shown to dissemble alpha-crystallin amyloid fibrils. To date, the dipeptide's anti-fibrillogensis effect has not been thoroughly characterized in other proteins. For a more complete understanding of carnosine's mechanism of action in amyloid fibril inhibition, we have investigated the effect of the dipeptide on lysozyme fibril formation and induced cytotoxicity in human neuroblastoma SH-SY5Y cells. Our study demonstrates a positive correlation between the concentration and inhibitory effect of carnosine against lysozyme fibril formation. Molecular docking results show carnosine's mechanism of fibrillogenesis inhibition may be initiated by binding with the aggregation-prone region of the protein. The dipeptide attenuates the amyloid fibril-induced cytotoxicity of human neuronal cells by reducing both apoptotic and necrotic cell deaths. Our study provides solid support for carnosine's amyloid fibril inhibitory property and its effect against fibril-induced cytotoxicity in SH-SY5Y cells. The additional insights gained herein may pave way to the discovery of other small molecules that may exert similar effects against amyloid fibril formation and its associated neurodegenerative diseases. PMID:24349167

Effect of hypergravity on lignin formation and expression of lignin-related genes in inflorescence stems of an ethylene-insensitive Arabidopsis mutant ein3-1

NASA Astrophysics Data System (ADS)

Karahara, Ichirou; Kobayashi, Mai; Tamaoki, Daisuke; Kamisaka, Seiichiro

Our previous studies have shown that hypergravity inhibits growth and promotes lignin forma-tion in inflorescence stems of Arabidopsis thaliana by up-regulation of genes involved in lignin biosynthesis (Tamaoki et al. 2006, 2009). In the present study, we have examined whether ethylene is involved in these responses using an ethylene-insensitive Arabidopsis mutant ein3-1. Our results revealed that hypergravity treatment at 300 G for 24 h significantly inhibited growth of inflorescence stems, promoted both deposition of acetyl bromide extractable lignin and gene expression involved in lignin formation in inflorescence stems of wild type plants. Growth inhibition of inflorescence stems was also observed in ein3-1. However, the effects of hypergravity on the promotion of the deposition of acetyl bromide lignin and the expression of genes involved in lignin formation were not observed in ein3-1, indicating that ethylene sig-naling is involved in the up-regulation of the expression of lignin-related genes as well as the promotion of deposition of lignin by hypergravity in Arabidopsis inflorescence stems.

Bedforms formed by experimental supercritical density flows

NASA Astrophysics Data System (ADS)

Naruse, Hajime; Izumi, Norihiro; Yokokawa, Miwa; Muto, Tetsuji

2014-05-01

This study reveals characteristics and formative conditions of bedforms produced by saline density flows in supercritical flow conditions, especially focusing on the mechanism of the formation of plane bed. The motion of sediment particles forming bedforms was resolved by high-speed cameras (1/1000 frame/seconds). Experimental density flows were produced by mixtures of salt water (1.01-1.04 in density) and plastic particles (1.5 in specific density, 140 or 240 mm in diameter). Salt water and plastic particles are analogue materials of muddy water and sand particles in turbidity currents respectively. Acrylic flume (4.0 m long, 2.0 cm wide and 0.5 m deep) was submerged in an experimental tank (6.0 m long, 1.8 m wide and 1.2 m deep) that was filled by clear water. Features of bedforms were observed when the bed state in the flume reached equilibrium condition. The experimental conditions range 1.5-4.2 in densimetric Froude number and 0.2-0.8 in Shields dimensionless stress. We report the two major discoveries as a result of the flume experiments: (1) Plane bed under Froude-supercritical flows and (2) Geometrical characteristics of cyclic steps formed by density flows. (1) Plane bed was formed under the condition of supercritical flow regime. In previous studies, plane bed has been known to be formed by subcritical unidirectional flows (ca. 0.8 in Froude number). However, this study implies that plane bed can also be formed by supercritical conditions with high Shields dimensionless stress (>0.4) and very high Froude number (> 4.0). This discovery may suggest that previous estimations of paleo-hydraulic conditions of parallel lamination in turbidites should be reconsidered. The previous experimental studies and data from high-speed camera suggest that the region of plane bed formation coincides with the region of the sheet flow developments. The particle transport in sheet flow (thick bedload layer) induces transform of profile of flow shear stress, which may be related with the formation of the plane bed. (2) This study also revealed geometrical characteristics of cyclic steps. Cyclic step is a type of bedform that is frequently observed in flanks of submarine levees. This study proved that cyclic steps of density flows show different geometry to those formed by open channel flows. Cyclic steps formed by open channel flows have generally asymmetrical geometry in which lee side is short, whereas cyclic steps formed by density flows are relatively symmetrical and varies their morphology remarkably depending on flow conditions.

Reevaluation of the Piermont-Frontenac allochthon in the Upper Connecticut Valley: Restoration of a coherent Boundary Mountains–Bronson Hill stratigraphic sequence

USGS Publications Warehouse

Rankin, Douglas W.; Tucker, Robert D.; Amelin, Yuri

2013-01-01

The regional extent and mode and time of emplacement of the Piermont-Frontenac allochthon in the Boundary Mountains–Bronson Hill anticlinorium of the Upper Connecticut Valley, New Hampshire–Vermont, are controversial. Moench and coworkers beginning in the 1980s proposed that much of the autochthonous pre–Middle Ordovician section of the anticlinorium was a large allochthon of Silurian to Early Devonian rocks correlated to those near Rangeley, Maine. This ∼200-km-long allochthon was postulated to have been transported westward in the latest Silurian to Early Devonian as a soft-sediment gravity slide on a hypothesized Foster Hill fault. New mapping and U-Pb geochronology do not support this interpretation. The undisputed Rangeley sequence in the Bean Brook slice is different from the disputed sequence in the proposed larger Piermont-Frontenac allochthon, and field evidence for the Foster Hill fault is lacking. At the type locality on Foster Hill, the postulated “fault” is a stratigraphic contact within the Ordovician Ammonoosuc Volcanics. The proposed Foster Hill fault would place the Piermont-Frontenac allochthon over the inverted limb of the Cornish(?) nappe, which includes the Emsian Littleton Formation, thus limiting the alleged submarine slide to post-Emsian time. Mafic dikes of the 419 Ma Comerford Intrusive Complex intrude previously folded strata attributed to the larger Piermont-Frontenac allochthon as well as the autochthonous Albee Formation and Ammonoosuc Volcanics. The Lost Nation pluton intruded and produced hornfels in previously deformed Albee strata. Zircons from an apophysis of the pluton in the hornfels have a thermal ionization mass spectrometry 207Pb/206Pb age of 444.1 ± 2.1 Ma. Tonalite near Bath, New Hampshire, has a zircon sensitive high-resolution ion microprobe 206Pb/238U age of 492.5 ± 7.8 Ma. The tonalite intrudes the Albee Formation, formerly interpreted as the Silurian Perry Mountain Formation of the proposed allochthon. Collectively, these features indicate that the large Piermont-Frontenac allochthon gravity slide of Silurian-Devonian strata, as previously proposed, cannot exist. Allochthonous rocks are restricted to a 25 km2 klippe, the Bean Brook slice, emplaced by hard-rock thrusting in the post-Emsian Devonian. The Albee Formation, the oldest unit in the study area, is older than the Late Cambrian tonalite at Bath. The correlation and apparent continuity along strike to the northeast of the Albee Formation with the Dead River Formation suggest that the Albee Formation, like the Dead River Formation, is of Ganderian affinity and that the Bronson Hill magmatic arc in the Upper Connecticut Valley was built on Ganderian crust. The Dead River Formation is unconformably overlain by Middle and Upper Ordovician volcanic units; the unconformity is attributed to the pre-Arenig Penobscottian orogeny. Some of the pre-Silurian deformation in the Upper Connecticut Valley may be Penobscottian rather than Taconian. New stratigraphic units defined herein include the pelitic Scarritt Member of the Albee Formation, the Ordovician Washburn Brook Formation consisting of synsedimentary breccia and coticule, chert, and ironstone, and the Devonian–Silurian Sawyer Mountain Formation, probably correlative with the Frontenac Formation. The Partridge Formation is partially coeval with the Ammonoosuc Volcanics.

Improving Joint Function Using Photochemical Hydrogels for Articular Surface Repair

DTIC Science & Technology

2012-10-01

with thrombin previously has been reported as a favorable scaffold for cartilage formation by encapsulated chondrocytes [10]. Studies over the past...during the photochemical crosslinking process. A full scale study is planned for the first quarter of year 3 to evaluate the fully formed cartilage ...Perform initial study of collagen and PEG gels with stem cells implanted in mice  Bone marrow MSCs were harvested from donor swine and grown in culture

Determination of dew point conditions for CO2 with impurities using microfluidics.

PubMed

Song, Wen; Fadaei, Hossein; Sinton, David

2014-03-18

Impurities can greatly modify the phase behavior of carbon dioxide (CO2), with significant implications on the safety and cost of transport in pipelines. In this paper we demonstrate a microfluidic approach to measure the dew point of such mixtures, specifically the point at which water in supercritical CO2 mixtures condenses to a liquid state. The method enables direct visualization of dew formation (∼ 1-2 μm diameter droplets) at industrially relevant concentrations, pressures, and temperatures. Dew point measurements for the well-studied case of pure CO2-water agreed well with previous theoretical and experimental data over the range of pressure (up to 13.17 MPa), temperature (up to 50 °C), and water content (down to 0.00229 mol fraction) studied. The microfluidic approach showed a nearly 3-fold reduction in error as compared to previous methods. When applied to a mixture with nitrogen (2.5%) and oxygen (5.8%) impurities--typical of flue gas from natural gas oxy-fuel combustion processes--the measured dew point pressure increased on average 17.55 ± 5.4%, indicating a more stringent minimum pressure for pipeline transport. In addition to increased precision, the microfluidic method offers a direct measurement of dew formation, requires very small volumes (∼ 10 μL), and is applicable to ultralow water contents (<0.005 mol fractions), circumventing the limits of previous methods.

Facile Five-Step Heteroepitaxial Growth of GaAs Nanowires on Silicon Substrates and the Twin Formation Mechanism.

PubMed

Yao, Maoqing; Sheng, Chunyang; Ge, Mingyuan; Chi, Chun-Yung; Cong, Sen; Nakano, Aiichiro; Dapkus, P Daniel; Zhou, Chongwu

2016-02-23

Monolithic integration of III-V semiconductors with Si has been pursued for some time in the semiconductor industry. However, the mismatch of lattice constants and thermal expansion coefficients represents a large technological challenge for the heteroepitaxial growth. Nanowires, due to their small lateral dimension, can relieve strain and mitigate dislocation formation to allow single-crystal III-V materials to be grown on Si. Here, we report a facile five-step heteroepitaxial growth of GaAs nanowires on Si using selective area growth (SAG) in metalorganic chemical vapor deposition, and we further report an in-depth study on the twin formation mechanism. Rotational twin defects were observed in the nanowire structures and showed strong dependence on the growth condition and nanowire size. We adopt a model of faceted growth to demonstrate the formation of twins during growth, which is well supported by both a transmission electron microscopy study and simulation based on nucleation energetics. Our study has led to twin-free segments in the length up to 80 nm, a significant improvement compared to previous work using SAG. The achievements may open up opportunities for future functional III-V-on-Si heterostructure devices.

Shocks in oscillated granular layers

NASA Astrophysics Data System (ADS)

Bougie, J.; Moon, Sung Joon; Swift, J. B.; Swinney, Harry L.

2001-11-01

We study shock formation in vertically oscillated granular layers, where shock waves form with each collision between the layer and the bottom plate of the container. We use both three-dimensional numerical solutions of continuum equations developed by Jenkins and Richman (J.T. Jenkins and M.W. Richman, Arch. Rat. Mech. Anal. 87), 355 (1985) for smooth and nearly elastic hard spheres, and previously validated molecular dynamics (MD) simulations (C. Bizon, M.D. Shattuck, J.B. Swift, W.D. McCormick, and H.L. Swinney, Phys. Rev. Lett. 80), 57 (1998). Both methods capture the shock formation, and the two methods agree quantitatively for small dissipation. We also investigate the effect of inelasticity on shock formation, and use both smooth and rough hard-sphere MD simulations to investigate the effect of friction in this system.

Upregulation of proinflammatory genes in skin lesions may be the cause of keloid formation (Review)

PubMed Central

DONG, XIANGLIN; MAO, SHAOLIN; WEN, HAO

2013-01-01

It was previously demonstrated that the main cause behind keloid formation may be keloid fibroblast abnormalities, which are closely associated with the microenvironment of the keloid lesion. The post-traumatic and chronic inflammation of the keloid lesion area suggest that inflammatory mediators play an important role in the keloid microenvironment and are crucial for keloid fibroblast abnormalities. In this study, we hypothesized that the mechanism underlying keloid formation may involve the continuous upregulation of proinflammatory gene expression in keloid lesions. This hypothesis may explain the inflammatory response, invasive growth and recurrence following resection of keloids, as well as the selective localization of keloids in specific parts of a patient’s body and the differences in localization among different patients. PMID:24649037

The formation of Hadley Rille and implications for the geology of the Apollo 15 region

NASA Technical Reports Server (NTRS)

Spudis, Paul D.; Swann, Gordon A.; Greeley, Ronald

1988-01-01

The results of studies of terrestrial lava tube systems and the regional and detailed site geology of the Apollo 15 area have been combined to develop a model for the formation of Hadley Rille. The regional geology of the Apennine bench formation and its relation to Mozart and Hadley Rilles is discussed. It is shown that the total thickness of mare basalt at the Apollo landing site is on the order of a few tens of meters, mostly less than 50 m. It is suggested that the role of thermal erosion in the development of sinuous rilles on the moon may be less important than previously assumed and that the assimilation of refractory highland rock types into mare basaltic magma is a minor lunar process.

Monitoring Ion Track Formation Using In Situ RBS/c, ToF-ERDA, and HR-PIXE

NASA Astrophysics Data System (ADS)

Karlušić, Marko; Fazinić, Stjepko; Siketić, Zdravko; Tadić, Tonči; Cosic, Donny; Božičević-Mihalić, Iva; Zamboni, Ivana; Jakšić, Milko; Schleberger, Marika

2017-09-01

The aim of this work is to investigate feasibility of the ion beam analysis techniques for monitoring swift heavy ion track formation. First, use of the in situ Rutherford backscattering spectroscopy in channeling mode to observe damage build-up in quartz SiO2 after MeV heavy ion irradiation is demonstrated. Second, new results of the in situ grazing incidence time-of-flight elastic recoil detection analysis used for monitoring the surface elemental composition during ion tracks formation in various materials are presented. Ion tracks were found on SrTiO3, quartz SiO2, a-SiO2 and muscovite mica surfaces by atomic force microscopy, but in contrast to our previous studies on GaN and TiO2, surface stoichiometry remained unchanged.

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

Eilert, André; Roberts, F. Sloan; Friebel, Daniel

Nanostructured copper cathodes are among the most efficient and selective catalysts to date for making multicarbon products from the electrochemical carbon dioxide reduction reaction (CO 2RR). We report an in situ X-ray absorption spectroscopy investigation of the formation of a copper nanocube CO 2RR catalyst with high activity that highly favors ethylene over methane production. The results show that the precursor for the copper nanocube formation is copper(I)-oxide, not copper(I)-chloride as previously assumed. A second route to an electrochemically similar material via a copper(II)–carbonate/hydroxide is also reported. In conclusion, this study highlights the importance of using oxidized copper precursors formore » constructing selective CO 2 reduction catalysts and shows the precursor oxidation state does not affect the electrocatalyst selectivity toward ethylene formation.« less

Containerless preparation of advanced optical glasses: Experiment 77F095

NASA Technical Reports Server (NTRS)

Happe, R. A.; Kim, K. S.

1982-01-01

Containerless processing of optical glasses was studied in preparation for space shuttle MEA flight experiments. Ground based investigation, experiment/hardware coordination activities and development of flight experiment and sample characterization plans were investigated. In the ground based investigation over 100 candidate glass materials for space processing were screened and promising compositions were identified. The system of Nb2O5-TiO2-CaO was found to be very rich with containerless glass compositions and as extensive number of the oxides combinations were tried resulting in a glass formation ternary phase diagram. The frequent occurrence of glass formation by containerless processing among the compositions for which no glass formations were previously reported indicated the possibility and an advantage of containerless processing in a terrestrial environment.

Simultaneous nanocalorimetry and fast XRD measurements to study the silicide formation in Pd/a-Si bilayers.

PubMed

Molina-Ruiz, Manel; Ferrando-Villalba, Pablo; Rodríguez-Tinoco, Cristian; Garcia, Gemma; Rodríguez-Viejo, Javier; Peral, Inma; Lopeandía, Aitor F

2015-05-01

The use of a membrane-based chip nanocalorimeter in a powder diffraction beamline is described. Simultaneous wide-angle X-ray scattering and scanning nanocalorimetric measurements are performed on a thin-film stack of palladium/amorphous silicon (Pd/a-Si) at heating rates from 0.1 to 10 K s(-1). The nanocalorimeter works under a power-compensation scheme previously developed by the authors. Kinetic and structural information of the consumed and created phases can be obtained from the combined techniques. The formation of Pd2Si produces a broad calorimetric peak that contains overlapping individual processes. It is shown that Pd consumption precedes the formation of the crystalline Pd2Si phase and that the crystallite size depends on the heating rate of the experiment.

Molecular hydrogen formation on interstellar PAHs through Eley-Rideal abstraction reactions

NASA Astrophysics Data System (ADS)

Foley, Nolan; Cazaux, S.; Egorov, D.; Boschman, L. M. P. V.; Hoekstra, R.; Schlathölter, T.

2018-06-01

We present experimental data on H2 formation processes on gas-phase polycyclic aromatic hydrocarbon (PAH) cations. This process was studied by exposing coronene radical cations, confined in a radio-frequency ion trap, to gas phase H atoms. Sequential attachment of up to 23 hydrogen atoms has been observed. Exposure to atomic D instead of H allows one to distinguish attachment from competing abstraction reactions, as the latter now leave a unique fingerprint in the measured mass spectra. Modeling of the experimental results using realistic cross sections and barriers for attachment and abstraction yield a 1:2 ratio of abstraction to attachment cross sections. The strong contribution of abstraction indicates that H2 formation on interstellar PAH cations is an order of magnitude more relevant than previously thought.

Formation of Bidisperse Particle Clouds

NASA Astrophysics Data System (ADS)

Er, Jenn Wei; Zhao, Bing; Law, Adrian W. K.; Adams, E. Eric

2014-11-01

When a group of dense particles is released instantaneously into water, their motion has been conceptualized as a circulating particle thermal (Ruggerber 2000). However, Wen and Nacamuli (1996) observed the formation of particle clumps characterized by a narrow, fast moving core shedding particles into wakes. They observed the clump formation even for particles in the non-cohesive range as long as the source Rayleigh number was large (Ra > 1E3) or equivalently the source cloud number (Nc) was small (Nc < 3.2E2). This physical phenomenon has been investigated by Zhao et al. (2014) through physical experiments. They proposed the theoretical support for Nc dependence and categorized the formation processes into cloud formation, transitional regime and clump formation. Previous works focused mainly on the behavior of monodisperse particles. The present study further extends the experimental investigation to the formation process of bidisperse particles. Experiments are conducted in a glass tank with a water depth of 90 cm. Finite amounts of sediments with various weight proportions between coarser and finer particles are released from a cylindrical tube. The Nc being tested ranges from 6E-3 to 9.9E-2, which covers all the three formation regimes. The experimental results showed that the introduction of coarse particles promotes cloud formation and reduce the losses of finer particles into the wake. More quantitative descriptions of the effects of source conditions on the formation processes will be presented during the conference.

Further optimization of culture method for rat keratinocytes: titration of glucose and sodium chloride.

PubMed

Oku, H; Yamashita, M; Iwasaki, H; Chinen, I

1999-02-01

The present study further improved the serum-free method of culturing rat keratinocytes. To obtain the best growth of rat keratinocytes, we modified our previous serum-free medium (MCDB153 based medium), particularly the amounts of glucose and sodium chloride (NaCl). Titration experiments showed the optimal concentration to be 0.8 mM for glucose and 100 mM for NaCl. This modification eliminated the requirement for albumin, which had been essential for colony formation when our previous medium was used. Titration of glucose and NaCl, followed by adjustment of essential amino acids and growth factors, produced a new formulation. More satisfactory and better growth was achieved with the new medium than with the previous medium. Accumulation of monoalkyldiacylglycerol (MADAG) was consistently noted in this study, representing the unusual lipid profile. A tendency toward normalization was, however, noted with the neutral lipid profile of keratinocytes cultivated in the new medium: lower production of MADAG was obtained with the new formulation, rather than the previous one.

Stars Take Longer to Form, Need a 'Kick' to Get Started, Astronomers Say

NASA Astrophysics Data System (ADS)

2002-01-01

Star formation is a longer process than previously thought, and is heavily dependent on outside events, such as supernova explosions, to trigger it, a team of astronomers has concluded. The scientists reached their conclusions after making a detailed study of a number of the dark gas clouds in which new stars are formed. Optical and mm-wave overlay of dark cloud Optical image of the dark cloud L57, with white contours indicating submillimeter-wave emission from dust within the dark cloud. "Our observations indicate that we need to drastically revise our ideas about the very early stages of star formation," said Claire Chandler, an astronomer at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico. Chandler, who worked with John Richer and Anja Visser at the Mullard Radio Astronomy Observatory in the United Kingdom, presented the results at the American Astronomical Society's meeting in Washington, D.C. The astronomers observed the gas clouds with the SCUBA camera on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. This instrument is sensitive to submillimeter-wavelength radiation, which lies between radio waves and infrared waves in the electromagnetic spectrum. They studied clouds that previously had been observed with optical and infrared telescopes. The SCUBA images allowed them to see aspects of the clouds not visible at other wavelengths. Some young "protostars" are so deeply embedded in their parent gas clouds that they are invisible to infrared telescopes, while others have become visible by consuming and blowing away much of their surrounding clouds. Earlier studies had indicated that the "invisible" stars are only about one-tenth as common as those visible to infrared telescopes. "What we see in our study, however, is equal numbers of both types," said Chandler, who added, "This means that both stages probably have about the same lifetime -- roughly 200,000 years each." Another conclusion coming from the study is that star formation is heavily dependent on a triggering event to get it started. Such a triggering event might be the shock wave from a supernova explosion that causes gas clouds to begin the gravitational collapse that ultimately results in a new star. Another challenge to traditional wisdom about the early stages of star formation came in the team's analysis of data on starless cores -- gas clouds that have not yet begun their collapse into stars. The astronomers found that the starless cores in their study are on the verge of collapsing, and probably have shorter lifetimes than previously thought. "This means that, contrary to what we thought before, you don't need strong magnetic fields to hold these things up against gravitational collapse, because they don't last that long," Chandler said. Much theoretical work on early star formation that focuses on the role of magnetic fields may need revision, the study indicates. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Exploration in Ordovician of central Michigan Basin

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

Fisher, J.H.; Barratt, M.W.

1985-12-01

Deep wells in the central Michigan basin have provided sufficient data to define two new mappable formations - the Foster Formation and the Bruggers Formation. Recent conodont studies have corrected the age assignments of the strata containing these formations. Previously, the lower section (Foster) was classified as mostly Cambrian, and the upper unit (Bruggers) was identified as Early Ordovician. Conodont identifications indicate an Early and Middle Ordovician age for the Foster Formation and a Middle Ordovician age for the Bruggers Formation. The Michigan basin existed in embryonic form in the Late Cambrian, but the full outline of the present-day basinmore » did not develop until Early Ordovician. Gas and condensate are produced from the Bruggers Formation as deep as 11,252 ft (3429 m). Geothermal investigations suggest that gas production is possible to the base of the Paleozoic section in the central basin (17,000 ft or 5181 m). Paleotemperatures were higher during the Paleozoic owing to 3000-4000 ft (914-1291 m) of additional sedimentary cover. Five wells are producing from the Bruggers Formation. All are deeper tests in anticlines producing from Devonian reservoirs discovered earlier. The structures are the result of vertical movements of basement fault blocks activated by regional stresses. 12 figures, 2 tables.« less

Chabazite and dolomite formation in a dolocrete profile: An example of a complex alkaline paragenesis in Lanzarote, Canary Islands

NASA Astrophysics Data System (ADS)

Alonso-Zarza, Ana M.; Bustamante, Leticia; Huerta, Pedro; Rodríguez-Berriguete, Álvaro; Huertas, María José

2016-05-01

This paper studies the weathering and soil formation processes operating on detrital sediments containing alkaline volcanic rock fragments of the Mirador del Río dolocrete profile. The profile consists of a lower horizon of removilised weathered basalts, an intermediate red sandy mudstones horizon with irregular carbonate layers and a topmost horizon of amalgamated carbonate layers with root traces. Formation occurred in arid to semiarid climates, giving place to a complex mineralogical association, including Mg-carbonates and chabazite, rarely described in cal/dolocretes profiles. Initial vadose weathering processes occurred in the basalts and in directly overlying detrital sediments, producing (Stage 1) red-smectites and dolomicrite. Dominant phreatic (Stage 2) conditions allowed precipitation of coarse-zoned dolomite and chabazite filling porosities. In Stages 3 and 4, mostly pedogenic, biogenic processes played an important role in dolomite and calcite accumulation in the profile. Overall evolution of the profile and its mineralogical association involved initial processes dominated by alteration of host rock, to provide silica and Mg-rich alkaline waters, suitable for chabazite and dolomite formation, without a previous carbonate phase. Dolomite formed both abiogenically and biogenically, but without a previous carbonate precursor and in the absence of evaporites. Dominance of calcite towards the profile top is the result of Mg/Ca decrease in the interstitial meteoric waters due to decreased supply of Mg from weathering, and increased supply of Ca in aeolian dust. Meteoric origin of the water is confirmed by C and O isotope values, which also indicate lack of deep sourced CO2. The dolocrete studied and its complex mineral association reveal the complex interactions that occur at surface during weathering and pedogenesis of basalt-sourced rocks.

The helicase-primase inhibitor BAY 57-1293 reduces the Alzheimer's disease-related molecules induced by herpes simplex virus type 1.

PubMed

Wozniak, M A; Frost, A L; Itzhaki, R F

2013-09-01

Herpes simplex virus type 1 (HSV1) infection of cultured cells causes the formation of β-amyloid (Aβ) and abnormal tau (P-tau). These molecules comprise the main components of the abnormal protein deposits, amyloid plaques and neurofibrillary tangles, respectively, in Alzheimer's disease (AD) brains, and they have been implicated in disease development. The formation of P-tau, but not of Aβ, depends on viral DNA replication, but nonetheless, three antiviral agents that inhibit HSV1 DNA replication, including acyclovir (ACV), were found to reduce greatly the level of Aβ as well as P-tau, the former probably through prevention of viral spread. Previous studies showed that HSV1 DNA is present and is active in the brain of many elderly people, including AD patients, and that in combination with the type 4 allele of the apolipoprotein E gene, it is likely to play a role in the disease, perhaps via Aβ and P-tau production. With the aim of finding the most suitable antiviral for inhibiting Aβ and P-tau formation as well as HSV1 DNA replication, for future use in a clinical trial for treating AD, we compared the efficacy of ACV with that of another antiviral, BAY 57-1293, which acts by a different mechanism from ACV. We found that BAY 57-1293 is more efficient than ACV not only in inhibiting HSV1 replication, confirming previous studies, but also in decreasing Aβ and P-tau formation. Also, the cell clusters that are formed during infection are reduced in size much more efficiently by BAY 57-1293 than by ACV. These data suggest that BAY 57-1293 would be a more effective agent than ACV for treating AD. Copyright © 2013 Elsevier B.V. All rights reserved.

Formation of current singularity in a topologically constrained plasma

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

Zhou, Yao; Huang, Yi-Min; Qin, Hong

2016-02-01

Recently a variational integrator for ideal magnetohydrodynamics in Lagrangian labeling has been developed. Its built-in frozen-in equation makes it optimal for studying current sheet formation. We use this scheme to study the Hahm-Kulsrud-Taylor problem, which considers the response of a 2D plasma magnetized by a sheared field under sinusoidal boundary forcing. We obtain an equilibrium solution that preserves the magnetic topology of the initial field exactly, with a fluid mapping that is non-differentiable. Unlike previous studies that examine the current density output, we identify a singular current sheet from the fluid mapping. These results are benchmarked with a constrained Grad-Shafranovmore » solver. The same signature of current singularity can be found in other cases with more complex magnetic topologies.« less

Constraints on formation processes of two coarse-grained calcium- aluminum-rich inclusions: a study of mantles, islands and cores

USGS Publications Warehouse

Meeker, G.P.

1995-01-01

Many coarse-grained calcium- aluminum-rich inclusions (CAIs) contain features that are inconsistent with equilibrium liquid crystallization models of origin. Spinel-free islands (SFIs) in spinel-rich cores of Type B CAIs are examples of such features. One model previously proposed for the origin of Allende 5241, a Type B1 CAI containing SFIs, involves the capture and assimilation of xenoliths by a liquid droplet in the solar nebula (El Goresy et al, 1985; MacPherson et al 1989). This study reports new textural and chemical zoning data from 5241 and identifies previously unrecognized chemical zoning patterns in the melilite mantle and in a SFI. -from Author

OMEGA - OSIRIS Mapping of Emission-line Galaxies in A901/2 - II. Environmental influence on integrated star formation properties and AGN activity

NASA Astrophysics Data System (ADS)

Rodríguez del Pino, Bruno; Aragón-Salamanca, Alfonso; Chies-Santos, Ana L.; Weinzirl, Tim; Bamford, Steven P.; Gray, Meghan E.; Böhm, Asmus; Wolf, Christian; Maltby, David T.

2017-06-01

We present a study of the star formation and AGN activity for galaxies in CP 15051 the Abell 901/2 multicluster system at z ˜ 0.167 as part of the OSIRIS Mapping of Emission-line Galaxies in A901/2 (OMEGA) survey. Using Tuneable Filter data obtained with the OSIRIS instrument at the Gran Telescopio Canarias, we produce spectra covering the Hα and [N II] spectral lines for more than 400 galaxies. Using optical emission-line diagnostics, we identify a significant number of galaxies hosting AGN, which tend to have high masses and a broad range of morphologies. Moreover, within the environmental densities probed by our study, we find no environmental dependence on the fraction of galaxies hosting AGN. The analysis of the integrated Hα emission shows that the specific star formation rates of a majority of the cluster galaxies are below the field values for a given stellar mass. We interpret this result as evidence for a slow decrease in the star formation activity of star-forming galaxies as they fall into higher density regions, contrary to some previous studies that suggested a rapid truncation of star formation. We find that most of the intermediate- and high-mass spiral galaxies go through a phase in which their star formation is suppressed but still retain significant star formation activity. During this phase, these galaxies tend to retain their spiral morphology while their colours become redder. The presence of this type of galaxies in high-density regions indicates that the physical mechanism responsible for suppressing star formation affects mainly the gas component of the galaxies, suggesting that ram-pressure stripping or starvation is potentially responsible.

Effects of unidirectional flow shear stresses on the formation, fractal microstructure and rigidity of incipient whole blood clots and fibrin gels.

PubMed

Badiei, N; Sowedan, A M; Curtis, D J; Brown, M R; Lawrence, M J; Campbell, A I; Sabra, A; Evans, P A; Weisel, J W; Chernysh, I N; Nagaswami, C; Williams, P R; Hawkins, K

2015-01-01

Incipient clot formation in whole blood and fibrin gels was studied by the rheometric techniques of controlled stress parallel superposition (CSPS) and small amplitude oscillatory shear (SAOS). The effects of unidirectional shear stress on incipient clot microstructure, formation kinetics and elasticity are reported in terms of the fractal dimension (df) of the fibrin network, the gel network formation time (TGP) and the shear elastic modulus, respectively. The results of this first haemorheological application of CSPS reveal the marked sensitivity of incipient clot microstructure to physiologically relevant levels of shear stress, these being an order of magnitude lower than have previously been studied by SAOS. CSPS tests revealed that exposure of forming clots to increasing levels of shear stress produces a corresponding elevation in df, consistent with the formation of tighter, more compact clot microstructures under unidirectional flow. A corresponding increase in shear elasticity was recorded. The scaling relationship established between shear elasticity and df for fibrin clots and whole blood confirms the fibrin network as the dominant microstructural component of the incipient clot in terms of its response to imposed stress. Supplementary studies of fibrin clot formation by rheometry and microscopy revealed the substantial additional network mass required to increase df and provide evidence to support the hypothesis that microstructural changes in blood clotted under unidirectional shear may be attributed to flow enhanced thrombin generation and activation. CSPS also identified a threshold value of unidirectional shear stress above which no incipient clot formation could be detected. CSPS was shown to be a valuable haemorheological tool for the study of the effects of physiological and pathological levels of shear on clot properties.

Hot or Not: The Role of Instructor Quality and Gender on the Formation of Positive Illusions among Students Using RateMyProfessors.com

ERIC Educational Resources Information Center

Theyson, Katherine C.

2015-01-01

Existing literature indicates that physical attractiveness positively affects variables such as income, perceived employee quality and performance evaluations. Similarly, in the academic arena, studies indicate instructors who are better looking receive better teaching evaluations from their students. Previous analysis of the website…

Model-Based Weighting and Comparisons: Research Report. ETS RR-08-17

ERIC Educational Resources Information Center

Qian, Jiahe

2008-01-01

In survey research, sometimes the formation of groupings, or aggregations of cases on which to make an inference, are of importance. Of particular interest are the situations where the cases aggregated carry useful information that has been transferred from a sample employed in a previous study. For example, a school to be included in the sample…

A Novel Cysteine-Rich Neurotrophic Factor in "Aplysia" Facilitates Growth, MAPK Activation, and Long-Term Synaptic Facilitation

ERIC Educational Resources Information Center

Pu, Lu; Kopec, Ashley M.; Boyle, Heather D.; Carew, Thomas J.

2014-01-01

Neurotrophins are critically involved in developmental processes such as neuronal cell survival, growth, and differentiation, as well as in adult synaptic plasticity contributing to learning and memory. Our previous studies examining neurotrophins and memory formation in "Aplysia" showed that a TrkB ligand is required for MAPK…

Atmospheric oxidation of isoprene and 1,3-Butadiene: influence of aerosol acidity and Relative humidity on secondary organic aerosol

EPA Science Inventory

The effects of acidic seed aerosols on the formation of secondary organic aerosol (SOA)have been examined in a number of previous studies, several of which have observed strong linear correlations between the aerosol acidity (measured as nmol H⁺ per m³ air s...

"I Just Want to Be 'Me' When I Am Exercising": Adrianna's Construction of a Vulnerable Exercise Identity

ERIC Educational Resources Information Center

Rossing, Hilde; Ronglan, Lars-Tore; Scott, Susie

2016-01-01

This study explores the social and dynamic aspects of the concept "exercise identity". Previous research, mainly in psychology, has documented a link between exercise identity and exercise behaviour. However, the process of identity formation is not straightforward but rather something that can change with time, context and interaction…

Bimodal Emotion Congruency Is Critical to Preverbal Infants' Abstract Rule Learning

ERIC Educational Resources Information Center

Tsui, Angeline Sin Mei; Ma, Yuen Ki; Ho, Anna; Chow, Hiu Mei; Tseng, Chia-huei

2016-01-01

Extracting general rules from specific examples is important, as we must face the same challenge displayed in various formats. Previous studies have found that bimodal presentation of grammar-like rules (e.g. ABA) enhanced 5-month-olds' capacity to acquire a rule that infants failed to learn when the rule was presented with visual presentation of…

Benefits of Interhemispheric Collaboration Can Be Eliminated by Mixing Stimulus Formats that Involve Different Cortical Access Routes

ERIC Educational Resources Information Center

Patel, Urvi J.; Hellige, Joseph B.

2007-01-01

Previous studies indicate that the benefits of dividing an information processing load across both cerebral hemispheres outweigh the costs of interhemispheric transfer as tasks become more difficult or cognitively complex. This is demonstrated as better performance when two stimuli to be compared are presented one to each visual field and…

Patterns of hybridization among cutthroat trout and rainbow trout in northern Rocky Mountain streams

Treesearch

Kevin S. McKelvey; Michael K. Young; Taylor M. Wilcox; Daniel M. Bingham; Kristine L. Pilgrim; Michael K. Schwartz

2016-01-01

Introgressive hybridization between native and introduced species is a growing conservation concern. For native cutthroat trout and introduced rainbow trout in western North America, this process is thought to lead to the formation of hybrid swarms and the loss of monophyletic evolutionary lineages. Previous studies of this phenomenon, however, indicated that...

Interteaching: Its Effects on Exam Scores in a Compressed-Schedule Format

ERIC Educational Resources Information Center

Zayac, Ryan M.; Paulk, Amber L.

2014-01-01

Although previous research has found interteaching to be an effective form of instruction, all of the currently published data have been collected in courses that have allowed for a minimum of 48 hours between class sessions. In the current study, we examined the effectiveness of interteaching compared to traditional lecture during a six week…

The Role of Gist and Verbatim Memory in Complex Decision Making: Explaining the Unconscious-Thought Effect

ERIC Educational Resources Information Center

Abadie, Marlène; Waroquier, Laurent; Terrier, Patrice

2017-01-01

Previous research showed that the "unconscious-thought effect", which refers to an improvement in complex decision making following a distraction period, was moderated by the presentation format of pieces of information about different options. The aim of the current study was to replicate this finding and further examine the memory…

Factors Affecting University Image Formation among Prospective Higher Education Students: The Case of International Branch Campuses

ERIC Educational Resources Information Center

Wilkins, Stephen; Huisman, Jeroen

2015-01-01

Previous research has found that the images of universities formed by prospective students greatly influence their choices. With the advent of international branch campuses in several higher education hubs worldwide, many international students now attempt to construct images of these institutions when deciding where to study. The aim of this…

The Impact of Changing Teaching Jobs on Music Teacher Identity, Role, and Perceptions of Role Support

ERIC Educational Resources Information Center

Gray, Lori F.

2011-01-01

This study utilized symbolic interaction as a framework to examine the impact of mobility on four veteran elementary general music teachers' identities, roles, and perceptions of role support. Previous research has focused on teacher identity formation among preservice and novice teachers; veteran teachers are less frequently represented in the…

Feeding blueberry diets to young rats dose-dependently inhibits bone resorption through suppression of rankl in stromal cells

USDA-ARS?s Scientific Manuscript database

Previous studies have demonstrated that weanling rats fed AIN-93G semi-purified diets supplemented with 10% whole blueberry (BB) powder for two weeks beginning on postnatal day 21 (PND21) significantly increased bone formation at PND35. However, the minimal level of dietary BB needed to produce thes...

Esherichia coli serotype O157:H7 retention on solid surfaces and peroxide resistance is enhanced by dual-strain biofilm formation

USDA-ARS?s Scientific Manuscript database

In a previous study we showed that an Escherichia coli O157:H7 strain that was unable to form biofilm could persist in large numbers in dual-strain biofilms formed with an E. coli O-:H4 companion strain. In this study we tested additional companion strains for their ability to retain serotype O157:H...

Comprehensive modeling study of ozonolysis of oleic acid aerosol based on real-time, online measurements of aerosol composition

NASA Astrophysics Data System (ADS)

Gallimore, P. J.; Griffiths, P. T.; Pope, F. D.; Reid, J. P.; Kalberer, M.

2017-04-01

The chemical composition of organic aerosols profoundly influences their atmospheric properties, but a detailed understanding of heterogeneous and in-particle reactivity is lacking. We present here a combined experimental and modeling study of the ozonolysis of oleic acid particles. An online mass spectrometry (MS) method, Extractive Electrospray Ionization (EESI), is used to follow the composition of the aerosol at a molecular level in real time; relative changes in the concentrations of both reactants and products are determined during aerosol aging. The results show evidence for multiple non-first-order reactions involving stabilized Criegee intermediates, including the formation of secondary ozonides and other oligomers. Offline liquid chromatography MS is used to confirm the online MS assignment of the monomeric and dimeric products. We explain the observed EESI-MS chemical composition changes, and chemical and physical data from previous studies, using a process-based aerosol chemistry simulation, the Pretty Good Aerosol Model (PG-AM). In particular, we extend previous studies of reactant loss by demonstrating success in reproducing the time dependence of product formation and the evolving particle size. This advance requires a comprehensive chemical scheme coupled to the partitioning of semivolatile products; relevant reaction and evaporation parameters have been refined using our new measurements in combination with PG-AM.

An uncertainty principle for star formation - II. A new method for characterising the cloud-scale physics of star formation and feedback across cosmic history

NASA Astrophysics Data System (ADS)

Kruijssen, J. M. Diederik; Schruba, Andreas; Hygate, Alexander P. S.; Hu, Chia-Yu; Haydon, Daniel T.; Longmore, Steven N.

2018-05-01

The cloud-scale physics of star formation and feedback represent the main uncertainty in galaxy formation studies. Progress is hampered by the limited empirical constraints outside the restricted environment of the Local Group. In particular, the poorly-quantified time evolution of the molecular cloud lifecycle, star formation, and feedback obstructs robust predictions on the scales smaller than the disc scale height that are resolved in modern galaxy formation simulations. We present a new statistical method to derive the evolutionary timeline of molecular clouds and star-forming regions. By quantifying the excess or deficit of the gas-to-stellar flux ratio around peaks of gas or star formation tracer emission, we directly measure the relative rarity of these peaks, which allows us to derive their lifetimes. We present a step-by-step, quantitative description of the method and demonstrate its practical application. The method's accuracy is tested in nearly 300 experiments using simulated galaxy maps, showing that it is capable of constraining the molecular cloud lifetime and feedback time-scale to <0.1 dex precision. Access to the evolutionary timeline provides a variety of additional physical quantities, such as the cloud-scale star formation efficiency, the feedback outflow velocity, the mass loading factor, and the feedback energy or momentum coupling efficiencies to the ambient medium. We show that the results are robust for a wide variety of gas and star formation tracers, spatial resolutions, galaxy inclinations, and galaxy sizes. Finally, we demonstrate that our method can be applied out to high redshift (z≲ 4) with a feasible time investment on current large-scale observatories. This is a major shift from previous studies that constrained the physics of star formation and feedback in the immediate vicinity of the Sun.

Embryo sac formation and early embryo development in Agave tequilana (Asparagaceae).

PubMed

González-Gutiérrez, Alejandra G; Gutiérrez-Mora, Antonia; Rodríguez-Garay, Benjamín

2014-01-01

Agave tequilana is an angiosperm species that belongs to the family Asparagaceae (formerly Agavaceae). Even though there is information regarding to some aspects related to the megagametogenesis of A. tequilana, this is the first report describing the complete process of megasporogenesis, megagametogenesis, the early embryo and endosperm development process in detail. The objective of this work was to study and characterize all the above processes and the distinctive morphological changes of the micropylar and chalazal extremes after fertilization in this species. The agave plant material for the present study was collected from commercial plantations in the state of Jalisco, Mexico. Ovules and immature seeds, previously fixed in FAA and kept in ethanol 70%, were stained based on a tissue clarification technique by using a Mayer's-Hematoxylin solution. The tissue clarification technique was successfully used for the characterization of the megasporogenesis, megagametogenesis, mature embryo sac formation, the early embryo and endosperm development processes by studying intact cells. The embryo sac of A. tequilana was confirmed to be of the monosporic Polygonum-type and an helobial endosperm formation. Also, the time-lapse of the developmental processes studied was recorded.

Presence of the dinosaur Scelidosaurus indicates Jurassic age for the Kayenta Formation (Glen Canyon Group, northern Arizona)

NASA Astrophysics Data System (ADS)

Padian, Kevin

1989-05-01

The Glen Canyon Group (Moenave, Wingate, Kayenta and Navajo Formations) of northern Arizona represents an extensive outcrop of early Mesozoic age terrestrial sediments. The age of these formations has long been disputed because independent stratigraphic data from marine tie-ins, paleobotanical and palynological evidence, and radiometric calibrations have been scanty or absent. The fauna of the Kayenta Formation in particular has been problematic because it has appeared to contain both typical Late Triassic and Early Jurassic taxa Here I report that the principal evidence for Late Triassic taxa, dermal scutes previously assigned to an aetosaur, in fact belongs to the thyreophoran ornithischian dinosaur Scelidosaurus, previously known only as a washed-in form found in marine sediments in the Early Jurassic of England. The presence of this dinosaur represents the first vertebrate biostratigraphic tie-in of the Glen Canyon Group horizons with reliably dated marine deposits in Europe. Together with revised systematic assessments of other vertebrates and independent evidence from fossil pollen, it supports an Early Jurassic age for the Kayenta Formation and most or all of the Glen Canyon Group.

Stratigraphy, sedimentology, and geothermal reservoir potential of the volcaniclastic Cura-Mallín succession at Lonquimay, Chile

NASA Astrophysics Data System (ADS)

Pedroza, Viviana; Le Roux, Jacobus P.; Gutiérrez, Néstor M.; Vicencio, Vladimir E.

2017-08-01

The Tolhuaca Volcano near Lonquimay in south-central Chile has been the subject of several studies due to its geothermal manifestations, but little is known about the stratigraphy and reservoir potential of the Cura-Mallín Formation forming its basement. Field work and U-Pb dating of detrital zircons allow us to redefine this succession as the Cura-Mallín Group, consisting of the volcano-sedimentary Guapitrío Formation, sedimentary Río Pedregoso Formation, and volcano-sedimentary Mitrauquén Formation. The Río Pedregoso Formation can be subdivided into three formal units, namely the Quilmahue Member, Rucañanco Member, and Bío-Bío Member. The base of the Quilmahue Member interfingers laterally with the base of the Guapitrío Formation, for which a previous K/Ar date of 22.0 ± 0.9 Ma was apparently discarded by the original authors. However, this date is consistent with the stratigraphic position of the Quilmahue Member and new zircon dates from the overlying units, also coinciding with the initiation of an extensional phase in the Bíobío-Aluminé Basin. Deposition of the Quilmahue Member continued throughout the early Miocene, as confirmed by dates of 17.5 Ma reported by previous authors and 16.5 Ma obtained in this study. The Rucañanco Member was deposited during the Serravalian around 12.6 Ma, whereas the Bío-Bío Member was dated at the Serravalian-Tortonian limit (11.6 Ma). Although all three members were deposited in a fluvio-lacustrine environment, they were dominated respectively by flood plains with crevasse splays, lake margins with distributary mouth bars and Gilbert-type deltas, and distal braided and meandering rivers. Whereas the Quilmahue Member was deposited during basin extension, the Rucañanco Member was formed during a period of basin inversion and compression. Temporary tectonic quiescence during deposition of the Bío-Bío Member allowed denudation of the landscape, but around 9.5 Ma tectonism was renewed again during deposition of the Mitrauquén Formation. From a geothermal point of view, the Guapitrío Formation has a low potential to host significant reservoirs due to extensive hydrothermal alteration that produced secondary minerals clogging pore spaces and fractures. In the Río Pedregoso Formation, on the other hand, the Rucañanco Member seems to have the best reservoir potential, as it has relatively thick, semi-permeable sandstones and conglomerates deposited in a lake-margin environment.

Evidence for the late formation of hydrous asteroids from young meteoritic carbonates.

PubMed

Fujiya, Wataru; Sugiura, Naoji; Hotta, Hideyuki; Ichimura, Koji; Sano, Yuji

2012-01-17

The accretion of small bodies in the Solar System is a fundamental process that was followed by planet formation. Chronological information of meteorites can constrain when asteroids formed. Secondary carbonates show extremely old (53)Mn-(53)Cr radiometric ages, indicating that some hydrous asteroids accreted rapidly. However, previous studies have failed to define accurate Mn/Cr ratios; hence, these old ages could be artefacts. Here we develop a new method for accurate Mn/Cr determination, and report a reliable age of 4,563.4+0.4/-0.5 million years ago for carbonates in carbonaceous chondrites. We find that these carbonates have identical ages, which are younger than those previously estimated. This result suggests the late onset of aqueous activities in the Solar System. The young carbonate age cannot be explained if the parent asteroid accreted within 3 million years after the birth of the Solar System. Thus, we conclude that hydrous asteroids accreted later than differentiated and metamorphosed asteroids.

Straight-chain halocarbon forming fluids for TRISO fuel kernel production - Tests with yttria-stabilized zirconia microspheres

NASA Astrophysics Data System (ADS)

Baker, M. P.; King, J. C.; Gorman, B. P.; Braley, J. C.

2015-03-01

Current methods of TRISO fuel kernel production in the United States use a sol-gel process with trichloroethylene (TCE) as the forming fluid. After contact with radioactive materials, the spent TCE becomes a mixed hazardous waste, and high costs are associated with its recycling or disposal. Reducing or eliminating this mixed waste stream would not only benefit the environment, but would also enhance the economics of kernel production. Previous research yielded three candidates for testing as alternatives to TCE: 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane. This study considers the production of yttria-stabilized zirconia (YSZ) kernels in silicone oil and the three chosen alternative formation fluids, with subsequent characterization of the produced kernels and used forming fluid. Kernels formed in silicone oil and bromotetradecane were comparable to those produced by previous kernel production efforts, while those produced in chlorooctadecane and iodododecane experienced gelation issues leading to poor kernel formation and geometry.

Pattern formation and three-dimensional instability in rotating flows

NASA Astrophysics Data System (ADS)

Christensen, Erik A.; Aubry, Nadine; Sorensen, Jens N.

1997-03-01

A fluid flow enclosed in a cylindrical container where fluid motion is created by the rotation of one end wall as a centrifugal fan is studied. Direct numerical simulations and spatio-temporal analysis have been performed in the early transition scenario, which includes a steady-unsteady transition and a breakdown of axisymmetric to three-dimensional flow behavior. In the early unsteady regime of the flow, the central vortex undergoes a vertical beating motion, accompanied by axisymmetric spikes formation on the edge of the breakdown bubble. As traveling waves, the spikes move along the central vortex core toward the rotating end-wall. As the Reynolds number is increased further, the flow undergoes a three-dimensional instability. The influence of the latter on the previous patterns is studied.

Degradation of curcumin: From mechanism to biological implications

PubMed Central

Schneider, Claus; Gordon, Odaine N.; Edwards, Rebecca L.; Luis, Paula B.

2016-01-01

Curcumin is the main bioactive ingredient in turmeric extract and widely consumed as part of the spice mix curry or as dietary supplement. Turmeric has a long history of therapeutic application in traditional Asian medicine. Biomedical studies conducted in the past two decades have identified a large number of cellular targets and effects of curcumin. In vitro curcumin rapidly degrades in an autoxidative transformation to diverse chemical species, formation of which has only recently been appreciated. We discuss how degradation and metabolism of curcumin, through products and their mechanism of formation, provide a basis for the interpretation of preclinical data and clinical studies. We suggest that the previously unrecognized diversity of its degradation products could be an important factor in explaining the polypharmacology of curcumin. PMID:25817068

Admittance Survey of Type 1 Coronae on Venus: Implications for Elastic Thickness

NASA Technical Reports Server (NTRS)

Hoogenboom, T.; Smrekar, S. E.; Anderson, F. S.; Houseman, G.

2003-01-01

Coronae are volcano-tectonic features on Venus which range from 60km to 2600km and are defined by their nearly circular patterns of fractures. Type 1 (regular) coronae are classified as having >50% complete fracture annuli. Previous work has examined the factors controlling the morphology, size, and fracture pattern of coronae, using lithospheric properties, loading signature and geologic characteristics. However, these studies have been limited to Type 2 (topographic) coronae (e.g. coronaes with <50% fracture annuli), and the factors controlling the formation of Type 1 coronae remain poorly understood. In this study, we apply the methodology of to survey the admittance signature for Type 1 coronae to determine the controlling parameters which govern Type 1 coronae formation.

Nanocrystalline hydroxyapatite bone substitute leads to sufficient bone tissue formation already after 3 months: histological and histomorphometrical analysis 3 and 6 months following human sinus cavity augmentation.

PubMed

Ghanaati, Shahram; Barbeck, Mike; Willershausen, Ines; Thimm, Benjamin; Stuebinger, Stefan; Korzinskas, Tadas; Obreja, Karina; Landes, Constantin; Kirkpatrick, Charles J; Sader, Robert A

2013-12-01

In this study the de novo bone formation capacity of a nanocrystalline hydroxyapatite bone substitute was assessed 3 and 6 months after its insertion into the human sinus cavity. Sinus cavity augmentation was performed in a total of 14 patients (n = 7 implantation after 3 months; n = 7 implantation after 6 months) with severely atrophic maxillary bone. The specimens obtained after 3 and 6 months were analyzed histologically and histomorphometrically with special focus on bone metabolism within the residual bone and the augmented region. This study revealed that bone tissue formation started from the bone-biomaterial-interface and was directed into the most cranial parts of the augmented region. There was no statistically significant difference in new bone formation after 3 and 6 months (24.89 ± 10.22% vs 31.29 ± 2.29%), respectively. Within the limits of the present study and according to previously published data, implant insertion in regions augmented with this bone substitute material could be considered already after 3 months. Further clinical studies with bone substitute materials are necessary to validate these findings. © 2012 Wiley Periodicals, Inc.

Deep Chandra Observations of HCG 16. I. Active Nuclei, Star Formation, and Galactic Winds

NASA Astrophysics Data System (ADS)

O'Sullivan, E.; Zezas, A.; Vrtilek, J. M.; Giacintucci, S.; Trevisan, M.; David, L. P.; Ponman, T. J.; Mamon, G. A.; Raychaudhury, S.

2014-10-01

We present new, deep Chandra X-ray and Giant Metrewave Radio Telescope 610 MHz observations of the spiral-galaxy-rich compact group HCG 16, which we use to examine nuclear activity, star formation, and high-luminosity X-ray binary populations in the major galaxies. We confirm the presence of obscured active nuclei in NGC 833 and NGC 835, and identify a previously unrecognized nuclear source in NGC 838. All three nuclei are variable on timescales of months to years, and for NGC 833 and NGC 835 this is most likely caused by changes in accretion rate. The deep Chandra observations allow us to detect for the first time an Fe Kα emission line in the spectrum of the Seyfert 2 nucleus of NGC 835. We find that NGC 838 and NGC 839 are both starburst-dominated systems, with only weak nuclear activity, in agreement with previous optical studies. We estimate the star formation rates in the two galaxies from their X-ray and radio emission, and compare these results with estimates from the infrared and ultraviolet bands to confirm that star formation in both galaxies is probably declining after galaxy-wide starbursts were triggered ~400-500 Myr ago. We examine the physical properties of their galactic superwinds, and find that both have temperatures of ~0.8 keV. We also examine the X-ray and radio properties of NGC 848, the fifth largest galaxy in the group, and show that it is dominated by emission from its starburst.

Cell wall properties play an important role in the emergence of lateral root primordia from the parent root.

PubMed

Roycewicz, Peter S; Malamy, Jocelyn E

2014-05-01

Plants adapt to their unique soil environments by altering the number and placement of lateral roots post-embryonic. Mutants were identified in Arabidopsis thaliana that exhibit increased lateral root formation. Eight mutants were characterized in detail and were found to have increased lateral root formation due to at least three distinct mechanisms. The causal mutation in one of these mutants was found in the XEG113 gene, recently shown to be involved in plant cell wall biosynthesis. Lateral root primordia initiation is unaltered in this mutant. In contrast, synchronization of lateral root initiation demonstrated that mutation of XEG113 increases the rate at which lateral root primordia develop and emerge to form lateral roots. The effect of the XEG113 mutation was specific to the root system and had no apparent effect on shoot growth. Screening of 17 additional cell wall mutants, altering a myriad of cell wall components, revealed that many (but not all) types of cell wall defects promote lateral root formation. These results suggest that proper cell wall biosynthesis is necessary to constrain lateral root primordia emergence. While previous reports have shown that lateral root emergence is accompanied by active remodelling of cell walls overlying the primordia, this study is the first to demonstrate that alteration of the cell wall is sufficient to promote lateral root formation. Therefore, inherent cell wall properties may play a previously unappreciated role in regulation of root system architecture.

Study on Flake Formation Behavior and Its Influence Factors in Cr5 Steel

PubMed Central

Chen, Huitao; Zhao, Wu; Yan, Liang

2018-01-01

A flake is a crack that is induced by trapped hydrogen within steel. To study its formation mechanism, previous studies mostly focused on the formation process and magnitude of hydrogen pressure in hydrogen traps such as cavities and cracks. However, according to recent studies, the hydrogen leads to the decline of the mechanical properties of steel, which is known as hydrogen embrittlement, is another reason for flake formation. In addition, the phenomenon of stress induced hydrogen uphill diffusion should not be neglected. All of the three behaviors are at work simultaneously. In order to further explore the formation mechanism of flakes in steel, the process of flake initiation and growth were studied with the following three coupling factors: trap hydrogen pressure, hydrogen embrittlement, and stress induced hydrogen re-distribution. The analysis model was established using the finite element method, and a crack whose radius is 0.5 mm was set in its center. The cohesive method and Bilinear Traction Separate Law (BTSL) were used to address the coupling effect. The results show that trap hydrogen pressure is the main driving force for flake formation. After the high hydrogen pressure was generated around the trap, a stress field formed. In addition, the trap is the center of stress concentration. Then, hydrogen is concentrated in a distribution around this trap, and most of the steel mechanical properties are reduced. The trap size is a key factor for defining the critical hydrogen content for flake formation and propagation. However, when the trap size exceeds the specified value, the critical hydrogen content does not change any more. As for the crack whose radius is 0.5 mm, the critical hydrogen content of Cr5VMo steel is 2.2 ppm, which is much closer to the maximum safe hydrogen concentration of 2.0 ppm used in China. The work presented in this article increases our understanding of flake formation and propagation mechanisms in steel. PMID:29702610

An examination of the impact of Olson’s extinction on tetrapods from Texas

PubMed Central

2018-01-01

It has been suggested that a transition between a pelycosaurian-grade synapsid dominated fauna of the Cisuralian (early Permian) and the therapsid dominated fauna of the Guadalupian (middle Permian) was accompanied by, and possibly driven by, a mass extinction dubbed Olson’s Extinction. However, this interpretation of the record has recently been criticised as being a result of inappropriate time-binning strategies: calculating species richness within international stages or substages combines extinctions occurring throughout the late Kungurian stage into a single event. To address this criticism, I examine the best record available for the time of the extinction, the tetrapod-bearing formations of Texas, at a finer stratigraphic scale than those previously employed. Species richness is calculated using four different time-binning schemes: the traditional Land Vertebrate Faunachrons (LVFs); a re-definition of the LVFs using constrained cluster analysis; individual formations treated as time bins; and a stochastic approach assigning specimens to half-million-year bins. Diversity is calculated at the genus and species level, both with and without subsampling, and extinction rates are also inferred. Under all time-binning schemes, both at the genus and species level, a substantial drop in diversity occurs during the Redtankian LVF. Extinction rates are raised above background rates throughout this time, but the biggest peak occurs in the Choza Formation (uppermost Redtankian), coinciding with the disappearance from the fossil record of several of amphibian clades. This study, carried out at a finer stratigraphic scale than previous examinations, indicates that Olson’s Extinction is not an artefact of the method used to bin data by time in previous analyses.

Inhibitory Effects of Yuzu and Its Components on Human Platelet Aggregation

PubMed Central

Kim, Tae-Ho; Kim, Hye-Min; Park, Se Won; Jung, Yi-Sook

2015-01-01

Our previous study demonstrated that yuzu has an anti-platelet effect in rat blood. In the present study, we examined whether the anti-platelet effect of yuzu can be extended to human blood by investigating its ability to inhibit aggregations induced by various agonists in human platelet rich plasma (PRP). This study also investigated the underlying mechanism of yuzu focusing on ADP granule secretion, TXB2 formations, and PLCγ/Akt signaling. The results from this study showed that ethanolic yuzu extract (YE), and its components, hesperidin and naringin, inhibited human platelet aggregation in a concentration-dependent manner. YE, hesperidin and naringin also inhibited TXB2 formation and ADP release. The phosphorylation of PLCγ and Akt was significantly inhibited by YE, heperidin and naringin. Furthermore, we demonstrated that YE, heperidin and naringin has anti-platelet effects in rat ex vivo studies, and lower side effects in mice tail bleeding time studies. The results from this study suggest that YE, hesperidin and naringin can inhibit human platelet aggregation, at least partly through the inhibition of PLCγ and Akt, leading to a decrease in TXB2 formation and granule secretion. PMID:25767683

Cooperation of endothelin-1 signaling with melanosomes plays a role in developing and/or maintaining human skin hyperpigmentation

PubMed Central

Murase, Daiki; Hachiya, Akira; Kikuchi-Onoe, Mamiko; Fullenkamp, Rachel; Ohuchi, Atsushi; Kitahara, Takashi; Moriwaki, Shigeru; Hase, Tadashi; Takema, Yoshinori

2015-01-01

ABSTRACT Skin hyperpigmentation is characterized by increased melanin synthesis and deposition that can cause significant psychosocial and psychological distress. Although several cytokine-receptor signaling cascades contribute to the formation of ultraviolet B-induced cutaneous hyperpigmentation, their possible involvement in other types of skin hyperpigmentation has never been clearly addressed. Since our continuous studies using skin specimens from more than 30 subjects with ethnic skin diversity emphasized a consistent augmentation in the expression of endothelin-1 (ET-1) and its receptor (Endothelin B receptor, ET-B) in hyperpigmented lesions, including senile lentigos (SLs), the precise function of ET-1 signaling was investigated in the present study. In line with previous studies, ET-1 significantly induced melanogenesis followed by increases in melanosome transport in melanocytes and in its transfer to keratinocytes while inhibition of ET-B function substantially depressed melanogenic ability in tissue-cultured SLs. Additionally, in agreement with a previous report that the formation of autophagosomes rather than melanosomes is stimulated according to starvation or defective melanosome production, ET-1 was found to remarkably augment the expression of components necessary for early melanosome formation, indicating its counteraction against autophagy-targeting melanosome degradation in melanocytes. Despite the lack of substantial impact of ET-1 on keratinocyte melanogenic functions, the expression of ET-1 was enhanced following melanosome uptake by keratinocytes. Taken together, our data suggest that ET-1 plays a substantial role in the development and/or maintenance of skin hyperpigmentation in reciprocal cooperation with increased melanosome incorporation. PMID:26340945

Trifluoperazine inhibits acetaminophen-induced hepatotoxicity and hepatic reactive nitrogen formation in mice and in freshly isolated hepatocytes.

PubMed

Banerjee, Sudip; Melnyk, Stepan B; Krager, Kimberly J; Aykin-Burns, Nukhet; McCullough, Sandra S; James, Laura P; Hinson, Jack A

2017-01-01

The hepatotoxicity of acetaminophen (APAP) occurs by initial metabolism to N-acetyl-p-benzoquinone imine which depletes GSH and forms APAP-protein adducts. Subsequently, the reactive nitrogen species peroxynitrite is formed from nitric oxide (NO) and superoxide leading to 3-nitrotyrosine in proteins. Toxicity occurs with inhibited mitochondrial function. We previously reported that in hepatocytes the nNOS (NOS1) inhibitor NANT inhibited APAP toxicity, reactive nitrogen and oxygen species formation, and mitochondrial dysfunction. In this work we examined the effect of trifluoperazine (TFP), a calmodulin antagonist that inhibits calcium induced nNOS activation, on APAP hepatotoxicity and reactive nitrogen formation in murine hepatocytes and in vivo . In freshly isolated hepatocytes TFP inhibited APAP induced toxicity, reactive nitrogen formation (NO, GSNO, and 3-nitrotyrosine in protein), reactive oxygen formation (superoxide), loss of mitochondrial membrane potential, decreased ATP production, decreased oxygen consumption rate, and increased NADH accumulation. TFP did not alter APAP induced GSH depletion in the hepatocytes or the formation of APAP protein adducts which indicated that reactive metabolite formation was not inhibited. Since we previously reported that TFP inhibits the hepatotoxicity of APAP in mice without altering hepatic APAP-protein adduct formation, we examined the APAP treated mouse livers for evidence of reactive nitrogen formation. 3-Nitrotyrosine in hepatic proteins and GSNO were significantly increased in APAP treated mouse livers and decreased in the livers of mice treated with APAP plus TFP. These data are consistent with a hypothesis that APAP hepatotoxicity occurs with altered calcium metabolism, activation of nNOS leading to increased reactive nitrogen formation, and mitochondrial dysfunction.

Effect of Sulfur Concentration and PH Conditions on Akaganeite Formation: Understanding Akaganeite Formation Conditions in Yellowknife Bay, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Fox, A.; Peretyazhko, T.; Sutter, B.; Niles, P.; Ming, D. W.; Morris, R. V.

2015-01-01

The Chemistry and Mineralogy Instrument (CHEMIN) on board the Mars Science Laboratory (MSL) Curiosity Rover identified minor amounts of akaganeite (beta-FeOOH) at Yellowknife Bay, Mars. There is also evidence for akaganeite at other localities on Mars from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Akaganeite is an iron(III) hydroxide with a hollandite- like structure and Cl in its tunnels. Terrestrial akaganeite usually forms in Cl-rich environments under acidic, oxidizing conditions. Previous studies of akaganeite have revealed that akaganeite formation is affected by the presence of sulfate (hereafter denoted as S. The prediction of circumneutral pH coupled with the detection of S at Yellowknife Bay dictate that work is needed to determine how S and pH together affect akaganeite formation. The goal of this work is to study how changes in both S concentration and pH influence akaganeite precipitation. Akaganeite formation was investigated at S/Cl molar ratios of 0, 0.017, 0.083, 0.17 and 0.33 at pH 1.5, 2, and 4. Results are anticipated to provide combined S concentration and pH constraints on akaganeite formation in Yellowknife Bay and elsewhere on Mars. Knowledge of solution pH and S concentrations can be utilized in understanding microbial habitability potential on the Martian surface.

Significance of Cholinergic and Peptidergic Nerves in Stress-Induced Ulcer and MALT Lymphoma Formation.

PubMed

Nakamura, Masahiko; Overby, Anders; Uehara, Akina; Oda, Masaya; Takahashi, Shinichi; Murayama, Somay Y; Matsui, Hidenori

2017-10-30

Backgound: The role of enteric nerves has previously been demonstrated in the formation of several gastric diseases. In the present review, the significance of the cholinergic nerves in stress-induced ulcer formation as well as the importance of substance P in the formation of gastric MALT lymphoma is discussed. The stress-induced ulcer was induced by the plaster bandage methods in rats. The gastric MALT lymphoma was formed by the peroral infection of gastric mucosal homogenate of the infected mouse in C57BL/6 mice. For the stress-induced ulcer, the distribution of the cholinergic nerves and muscarinic acetylcholine receptors was investigated by acetylcholinesterase histochemistry and autoradiography of water soluble compounds using 3H-quinuclidinyl benzilate was performed. To the MALT lymphoma study, the distribution of the substance P and effect of substance P antagonist, spantide II, was investigated by immunohistochemical studies. The stress induced ulcer formation was shown to be related to the hyperactivity of the cholinergic nerves. The gastric MALT lymphoma was shown to be related to the increased localization of substance P. Stress-induced ulceration as a model of hyperactivity of the cholinergic nerves was proved to be a useful approach, while substance P and its role in MALT lymphoma formation may serve as a tool to clarify the neuroimmune modulation of chronic infectious diseases. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

The Vaporization of B2O3(l) to B2O3(g) and B2O2(g)

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.; Myers, Dwight L.

2011-01-01

The vaporization of B2O3 in a reducing environment leads to formation of both B2O3(g) and B2O2(g). While formation of B2O3(g) is well understood, many questions about the formation of B2O2(g) remain. Previous studies using B(s) + B2O3(l) have led to inconsistent thermodynamic data. In this study, it was found that after heating, B(s) and B2O3(l) appear to separate and variations in contact area likely led to the inconsistent vapor pressures of B2O2(g). To circumvent this problem, an activity of boron is fixed with a two-phase mixture of FeB and Fe2B. Both second and third law enthalpies of formation were measured for B2O2(g) and B2O3(g). From these the enthalpies of formation at 298.15 K are calculated to be -479.9 +/- 41.5 kJ/mol for B2O2(g) and -833.4 +/- 13.1 kJ/mol for B2O3(g). Ab initio calculations to determine the enthalpies of formation of B2O2(g) and B2O3(g) were conducted using the W1BD composite method and show good agreement with the experimental values.

Luteolin suppresses angiogenesis and vasculogenic mimicry formation through inhibiting Notch1-VEGF signaling in gastric cancer.

PubMed

Zang, Mingde; Hu, Lei; Zhang, Baogui; Zhu, Zhenglun; Li, Jianfang; Zhu, Zhenggang; Yan, Min; Liu, Bingya

2017-08-26

Gastric cancer is a great threat to the health of the people worldwide and lacks effective therapeutic regimens. Luteolin is one of Chinese herbs and presents in many fruits and green plants. In our previous study, we observed that luteolin inhibited cell migration and promoted cell apoptosis in gastric cancer. In the present study, luteolin significantly inhibited tube formation of human umbilical vein endothelial cells (HUVECs) through decreasing cell migration and proliferation of HUVECs in a dose-dependent manner. Vasculogenic mimicry (VM) tubes formed by gastric cancer cells were also inhibited with luteolin treatment. To explore how luteolin inhibited tubes formation, ELISA assay for VEGF was performed. Both of the VEGF secretion from Hs-746T cells and HUVECs were significantly decreased subsequent to luteolin treatment. In addition, cell migration was increased with the interaction between gastric cancer cells and HUVECs in co-culture assays. However, the promoting effects were abolished subsequent to luteolin treatment. Furthermore, luteolin inhibited VEGF secretion through suppressing Notch1 expression in gastric cancer. Overexpression of Notch1 in gastric cancer cells partially rescued the effects on cell migration, proliferation, HUVECs tube formation, and VM formation induced by luteolin treatment. In conclusion, luteolin inhibits angiogenesis and VM formation in gastric cancer through suppressing VEGF secretion dependent on Notch1 expression. Copyright © 2017 Elsevier Inc. All rights reserved.

Secondary formation of disinfection by-products by UV treatment of swimming pool water.

PubMed

Spiliotopoulou, Aikaterini; Hansen, Kamilla M S; Andersen, Henrik R

2015-07-01

Formation of disinfection by-products (DBPs) during experimental UV treatment of pool water has previously been reported with little concurrence between laboratory studies, field studies and research groups. In the current study, changes in concentration of seven out of eleven investigated volatile DBPs were observed in experiments using medium pressure UV treatment, with and without chlorine and after post-UV chlorination. Results showed that post-UV chlorine consumption increased, dose-dependently, with UV treatment dose. A clear absence of trihalomethane formation by UV and UV with chlorine was observed, while small yet statistically significant increases in dichloroacetonitrile and dichloropropanone concentrations were detected. Results indicate that post-UV chlorination clearly induced secondary formation of several DBPs. However, the formation of total trihalomethanes was no greater than what could be replicated by performing the DBP formation assay with higher chlorine concentrations to simulate extended chlorination. Post-UV chlorination of water from a swimming pool that continuously uses UV treatment to control combined chlorine could not induce secondary formation for most DBPs. Concurrence for induction of trihalomethanes was identified between post-UV chlorination treatments and simulated extended chlorination time treatment. Trihalomethanes could not be induced by UV treatment of water from a continuously UV treated pool. This indicates that literature reports of experimentally induced trihalomethane formation by UV may be a result of kinetic increase in formation by UV. However, this does not imply that higher trihalomethane concentrations would occur in pools that apply continuous UV treatment. The bromine fraction of halogens in formed trihalomethanes increased with UV dose. This indicates that UV removes bromine atoms from larger molecules that participate in trihalomethane production during post-UV chlorination. Additionally, no significant effect on DBP formation was observed due to photo-inducible radical forming molecules NO3- (potentially present in high concentrations in pool water) and H2O2 (added as part of commercially employed DBP reducing practices). Copyright © 2015 Elsevier B.V. All rights reserved.

INVESTIGATING THE EFFECT OF MICROBIAL GROWTH AND BIOFILM FORMATION ON SEISMIC WAVE PROPAGATION IN SEDIMENT

EPA Science Inventory

Previous laboratory investigations have demonstrated that the seismic methods are sensitive to microbially-induced changes in porous media through the generation of biogenic gases and biomineralization. The seismic signatures associated with microbial growth and biofilm formation...

IDENTIFICATION OF CHLOROMETHANE FORMATION PATHS DURING ELECTROCHEMICAL DECHLORINATION OF TCE USING GRAPHITE ELECTRODES

EPA Science Inventory

The purpose of this research is to investigate the formation of chloromethane during TCE dechlorination in a mixed electrochemical reactor using graphite electrodes. Chloromethane was the major chlorinated organic compound detected in previous dechlorination experiments. In order...

Telomerase deficiency in bone marrow-derived cells attenuates angiotensin II-induced abdominal aortic aneurysm formation.

PubMed

Findeisen, Hannes M; Gizard, Florence; Zhao, Yue; Cohn, Dianne; Heywood, Elizabeth B; Jones, Karrie L; Lovett, David H; Howatt, Deborah A; Daugherty, Alan; Bruemmer, Dennis

2011-02-01

Abdominal aortic aneurysms (AAA) are an age-related vascular disease and an important cause of morbidity and mortality. In this study, we sought to determine whether the catalytic component of telomerase, telomerase reverse transcriptase (TERT), modulates angiotensin (Ang) II-induced AAA formation. Low-density lipoprotein receptor-deficient (LDLr-/-) mice were lethally irradiated and reconstituted with bone marrow-derived cells from TERT-deficient (TERT-/-) mice or littermate wild-type mice. Mice were placed on a diet enriched in cholesterol, and AAA formation was quantified after 4 weeks of Ang II infusion. Repopulation of LDLr-/- mice with TERT-/- bone marrow-derived cells attenuated Ang II-induced AAA formation. TERT-deficient recipient mice revealed modest telomere attrition in circulating leukocytes at the study end point without any overt effect of the donor genotype on white blood cell counts. In mice repopulated with TERT-/- bone marrow, aortic matrix metalloproteinase-2 (MMP-2) activity was reduced, and TERT-/- macrophages exhibited decreased expression and activity of MMP-2 in response to stimulation with Ang II. Finally, we demonstrated in transient transfection studies that TERT overexpression activates the MMP-2 promoter in macrophages. TERT deficiency in bone marrow-derived macrophages attenuates Ang II-induced AAA formation in LDLr-/- mice and decreases MMP-2 expression. These results point to a previously unrecognized role of TERT in the pathogenesis of AAA.

A long-term study of new particle formation in a coastal environment: meteorology, gas phase and solar radiation implications.

PubMed

Sorribas, M; Adame, J A; Olmo, F J; Vilaplana, J M; Gil-Ojeda, M; Alados-Arboledas, L

2015-04-01

New particle formation (NPF) was investigated at a coastal background site in Southwest Spain over a four-year period using a Scanning Particle Mobility Sizer (SMPS). The goals of the study were to characterise the NPF and to investigate their relationship to meteorology, gas phase (O3, SO2, CO and NO2) and solar radiation (UVA, UVB and global). A methodology for identifying and classifying the NPF was implemented using the wind direction and modal concentrations as inputs. NPF events showed a frequency of 24% of the total days analysed. The mean duration was 9.2±4.2 h. Contrary to previous studies conducted in other locations, the NPF frequency reached its maximum during cold seasons for approximately 30% of the days. The lowest frequency took place in July with 10%, and the seasonal wind pattern was found to be the most important parameter influencing the NPF frequency. The mean formation rate was 2.2±1.7 cm(-3) s(-1), with a maximum in the spring and early autumn and a minimum during the summer and winter. The mean growth rate was 3.8±2.4 nm h(-1) with higher values occurring from spring to autumn. The mean and seasonal formation and growth rates are in agreement with previous observations from continental sites in the Northern Hemisphere. NPF classification of different classes was conducted to explore the effect of synoptic and regional-scale patterns on NPF and growth. The results show that under a breeze regime, the temperature indirectly affects NPF events. Higher temperatures increase the strength of the breeze recirculation, favouring gas accumulation and subsequent NPF appearance. Additionally, the role of high relative humidity in inhibiting the NPF was evinced during synoptic scenarios. The remaining meteorological variables (RH), trace gases (CO and NO), solar radiation, PM10 and condensation sink, showed a moderate or high connection with both formation and growth rates. Copyright © 2014 Elsevier B.V. All rights reserved.

Two-Hydrophone Heading and Range Sensor Applied to Formation-Flying for AUVs

DTIC Science & Technology

2004-01-01

d=0.914 m, and c=1371.6 m/s. The leader was given a lawn - mower waypoint trajectory, and the follower’s waypoint trajectory was obtained by...shifting the leader’s trajectory by a desired distance. For the 40yd-abreast formation and the 10yd-abreast formation, the leader’s lawn - mower path was...shifted by 40yd and 10yd respectively. For the wedge formation, they still followed the same lawn - mower path as the previous one, but the follower

Chondrule formation, metamorphism, brecciation, an important new primary chondrule group, and the classification of chondrules

NASA Technical Reports Server (NTRS)

Sears, Derek W. G.; Shaoxiong, Huang; Benoit, Paul H.

1995-01-01

The recently proposed compositional classification scheme for meteoritic chondrules divides the chondrules into groups depending on the composition of their two major phases, olivine (or pyroxene) and the mesostasis, both of which are genetically important. The scheme is here applied to discussions of three topics: the petrographic classification of Roosevelt County 075 (the least-metamorphosed H chondrite known), brecciation (an extremely important and ubiquitous process probably experienced by greater than 40% of all unequilibrated ordinary chondrites), and the group A5 chondrules in the least metamorphosed ordinary chondrites which have many similarities to chondrules in the highly metamorphosed 'equilibrated' chondrites. Since composition provides insights into both primary formation properties of the chondruies and the effects of metamorphism on the entire assemblage it is possible to determine the petrographic type of RC075 as 3.1 with unique certainty. Similarly, the near scheme can be applied to individual chondrules without knowledge of the petrographic type of the host chondrite, which makes it especially suitable for studying breccias. Finally, the new scheme has revealed the existence of chondrules not identified by previous techniques and which appear to be extremely important. Like group A1 and A2 chondrules (but unlike group B1 chondrules) the primitive group A5 chondruies did not supercool during formation, but unlike group A1 and A2 chondrules (and like group B1 chondrules) they did not suffer volatile loss and reduction during formation. It is concluded that the compositional classification scheme provides important new insights into the formation and history of chondrules and chondrites which would be overlooked by previous schemes.

The epidermal Ca(2+) gradient: Measurement using the phasor representation of fluorescent lifetime imaging.

PubMed

Celli, A; Sanchez, S; Behne, M; Hazlett, T; Gratton, E; Mauro, T

2010-03-03

Ionic gradients are found across a variety of tissues and organs. In this report, we apply the phasor representation of fluorescence lifetime imaging data to the quantitative study of ionic concentrations in tissues, overcoming technical problems of tissue thickness, concentration artifacts of ion-sensitive dyes, and calibration across inhomogeneous tissue. We used epidermis as a model system, as Ca(2+) gradients in this organ have been shown previously to control essential biologic processes of differentiation and formation of the epidermal permeability barrier. The approach described here allowed much better localization of Ca(2+) stores than those used in previous studies, and revealed that the bulk of free Ca(2+) measured in the epidermis comes from intracellular Ca(2+) stores such as the Golgi and the endoplasmic reticulum, with extracellular Ca(2+) making a relatively small contribution to the epidermal Ca(2+) gradient. Due to the high spatial resolution of two-photon microscopy, we were able to measure a marked heterogeneity in average calcium concentrations from cell to cell in the basal keratinocytes. This finding, not reported in previous studies, calls into question the long-held hypothesis that keratinocytes increase intracellular Ca(2+), cease proliferation, and differentiate passively in response to changes in extracellular Ca(2+). The experimental results obtained using this approach illustrate the power of the experimental and analytical techniques outlined in this report. Our approach can be used in mechanistic studies to address the formation, maintenance, and function of the epidermal Ca(2+) gradient, and it should be broadly applicable to the study of other tissues with ionic gradients. 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Repair for mitral stenosis due to pannus formation after Duran ring annuloplasty.

PubMed

Song, Seunghwan; Cho, Seong Ho; Yang, Ji-Hyuk; Park, Pyo Won

2010-12-01

Mitral stenosis after mitral repair with using an annuloplasty ring is not common and it is almost always due to pannus formation. Mitral valve replacement was required in most of the previous cases of pannus covering the mitral valve leaflet, which could not be stripped off without damaging the valve leaflets. In two cases, we removed the previous annuloplasty ring and pannus without leaflet injury, and we successfully repaired the mitral valve. During the follow-up of 4 months and 39 months respectively, we observed improvement of the patients' symptoms and good valvular function. Redo mitral repair may be a possible method for treating mitral stenosis due to pannus formation after ring annuloplasty. Copyright © 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

A possible connection between the spin temperature of damped Lyman α absorption systems and star formation history

NASA Astrophysics Data System (ADS)

Curran, S. J.

2017-09-01

We present a comprehensive analysis of the spin temperature/covering factor degeneracy, Tspin/f, in damped Lyman α absorption systems. By normalizing the upper limits and including these via a survival analysis, there is, as previously claimed, an apparent increase in Tspin/f with redshift at zabs ≳ 1. However, when we account for the geometry effects of an expanding Universe, neglected by the previous studies, this increase in Tspin at zabs ≳ 1 is preceded by a decrease at zabs ≲ 1. Using high resolution radio images of the background continuum sources, we can transform the Tspin/f degeneracy to T_spin/d_abs^{ 2}, where dabs is the projected linear size of the absorber. Again, there is no overall increase with redshift, although a dip at zabs ≈ 2 persists. Furthermore, we find d_abs^{ 2}/T_spin to follow a similar variation with redshift as the star formation rate, ψ*. This suggests that, although the total hydrogen column density, N_{H I}, shows little relation to ψ*, the fraction of the cold neutral medium, \\int τ_obs dv/N_{H I}, may. Therefore, further efforts to link the neutral gas with the star formation history should also consider the cool component of the gas.

The pgaABCD Locus of Escherichia coli Promotes the Synthesis of a Polysaccharide Adhesin Required for Biofilm Formation

PubMed Central

Wang, Xin; Preston, James F.; Romeo, Tony

2004-01-01

Production of a polysaccharide matrix is a hallmark of bacterial biofilms, but the composition of matrix polysaccharides and their functions are not widely understood. Previous studies of the regulation of Escherichia coli biofilm formation suggested the involvement of an unknown adhesin. We now establish that the pgaABCD (formerly ycdSRQP) locus affects biofilm development by promoting abiotic surface binding and intercellular adhesion. All of the pga genes are required for optimal biofilm formation under a variety of growth conditions. A pga-dependent cell-bound polysaccharide was isolated and determined by nuclear magnetic resonance analyses to consist of unbranched β-1,6-N-acetyl-d-glucosamine, a polymer previously unknown from the gram-negative bacteria but involved in adhesion by staphylococci. The pga genes are predicted to encode envelope proteins involved in synthesis, translocation, and possibly surface docking of this polysaccharide. As predicted, if poly-β-1,6-GlcNAc (PGA) mediates cohesion, metaperiodate caused biofilm dispersal and the release of intact cells, whereas treatment with protease or other lytic enzymes had no effect. The pgaABCD operon exhibits features of a horizontally transferred locus and is present in a variety of eubacteria. Therefore, we propose that PGA serves as an adhesin that stabilizes biofilms of E. coli and other bacteria. PMID:15090514

Formation and spatial distribution of hypervelocity stars in AGN outflows

NASA Astrophysics Data System (ADS)

Wang, Xiawei; Loeb, Abraham

2018-05-01

We study star formation within outflows driven by active galactic nuclei (AGN) as a new source of hypervelocity stars (HVSs). Recent observations revealed active star formation inside a galactic outflow at a rate of ∼ 15M⊙yr-1 . We verify that the shells swept up by an AGN outflow are capable of cooling and fragmentation into cold clumps embedded in a hot tenuous gas via thermal instabilities. We show that cold clumps of ∼ 103 M⊙ are formed within ∼ 105 yrs. As a result, stars are produced along outflow's path, endowed with the outflow speed at their formation site. These HVSs travel through the galactic halo and eventually escape into the intergalactic medium. The expected instantaneous rate of star formation inside the outflow is ∼ 4 - 5 orders of magnitude greater than the average rate associated with previously proposed mechanisms for producing HVSs, such as the Hills mechanism and three-body interaction between a star and a black hole binary. We predict the spatial distribution of HVSs formed in AGN outflows for future observational probe.

Toward a computational model of hemostasis

NASA Astrophysics Data System (ADS)

Leiderman, Karin; Danes, Nicholas; Schoeman, Rogier; Neeves, Keith

2017-11-01

Hemostasis is the process by which a blood clot forms to prevent bleeding at a site of injury. The formation time, size and structure of a clot depends on the local hemodynamics and the nature of the injury. Our group has previously developed computational models to study intravascular clot formation, a process confined to the interior of a single vessel. Here we present the first stage of an experimentally-validated, computational model of extravascular clot formation (hemostasis) in which blood through a single vessel initially escapes through a hole in the vessel wall and out a separate injury channel. This stage of the model consists of a system of partial differential equations that describe platelet aggregation and hemodynamics, solved via the finite element method. We also present results from the analogous, in vitro, microfluidic model. In both models, formation of a blood clot occludes the injury channel and stops flow from escaping while blood in the main vessel retains its fluidity. We discuss the different biochemical and hemodynamic effects on clot formation using distinct geometries representing intra- and extravascular injuries.

Development of a liquid metal slip ring

NASA Technical Reports Server (NTRS)

Weinberger, S. M.

1972-01-01

A liquid metal slip ring/solar orientation mechanism was designed and a model tested. This was a follow-up of previous efforts for the development of a gallium liquid metal slip ring in which the major problem was the formation and ejection of debris. A number of slip ring design approaches were studied. The probe design concept was fully implemented with detail drawings and a model was successfully tested for dielectric strength, shock vibration, acceleration and operation. The conclusions are that a gallium liquid metal slip ring/solar orientation mechanism is feasible and that the problem of debris formation and ejection has been successfully solved.

Inhibition of beta-amyloid aggregation by fluorescent dye labels

NASA Astrophysics Data System (ADS)

Amaro, Mariana; Wellbrock, Thorben; Birch, David J. S.; Rolinski, Olaf J.

2014-02-01

The fluorescence decay of beta-amyloid's (Aβ) intrinsic fluorophore tyrosine has been used for sensing the oligomer formation of dye-labelled Aβ monomers and the results compared with previously studied oligomerization of the non-labelled Aβ peptides. It has been demonstrated that two different sized, covalently bound probes 7-diethylaminocoumarin-3-carbonyl and Hilyte Fluor 488 (HLF), alter the rate and character of oligomerization to different extents. The ability of HLF to inhibit formation of highly ordered structures containing beta-sheets was also shown. The implications of our findings for using fluorescence methods in amyloidosis research are discussed and the advantages of this auto-fluorescence approach highlighted.

Developmental mechanisms of the tympanic membrane in mammals and non-mammalian amniotes.

PubMed

Takechi, Masaki; Kitazawa, Taro; Hirasawa, Tatsuya; Hirai, Tamami; Iseki, Sachiko; Kurihara, Hiroki; Kuratani, Shigeru

2016-01-01

The tympanic membrane is a thin layer that originates from the ectoderm, endoderm, and mesenchyme. Molecular-genetic investigations have revealed that interaction between epithelial and mesenchymal cells in the pharyngeal arches is essential for development of the tympanic membrane. We have recently reported that developmental mechanisms underlying the tympanic membrane seem to be different between mouse and chicken, suggesting that the tympanic membrane evolved independently in mammals and non-mammalian amniotes. In this review, we summarize previous studies of tympanic membrane formation in the mouse. We also discuss its formation in amniotes from an evolutionary point of view. © 2015 Japanese Teratology Society.

Retigeric acid B enhances the efficacy of azoles combating the virulence and biofilm formation of Candida albicans.

PubMed

Chang, Wenqiang; Li, Ying; Zhang, Li; Cheng, Aixia; Liu, Yongqing; Lou, Hongxiang

2012-01-01

Candida albicans is one of the most prevalent human opportunistic pathogens. C. albicans undergoes a yeast-to-hyphal transition that has been identified as a virulence factor as well as a critical element for mature biofilm formation. A previous study in our lab showed retigeric acid B (RAB), a lichen derived pentacyclic triterpenoid, displayed synergistic antifungal activity with azoles. We now showed that this combination also proved to be adequate in combating the formation of hyphae in vitro. In vivo tests with mice demonstrated RAB could markedly enhance the efficacy of fluconazole to promote the host's longevity through inhibiting hyphae formation and adherence to host cells. It was also observed that RAB and azoles interacted synergistically to block the formation of biofilm. Our data suggested the attenuated yeast-to-hyphal switch contributed to the defect of mature biofilm formation. Moreover, quantitative real-time polymerase chain reaction (qPCR) analysis showed RAB could reduce the transcript level of MDR1, a multidrug efflux pump, and caused a slight transcriptional reduction for another drug pump related gene CDR1. Taken together, our work provides a potential application to combat candidiasis using the combination of RAB and azoles.

Two innovative pore pressure calculation methods for shallow deep-water formations

NASA Astrophysics Data System (ADS)

Deng, Song; Fan, Honghai; Liu, Yuhan; He, Yanfeng; Zhang, Shifeng; Yang, Jing; Fu, Lipei

2017-11-01

There are many geological hazards in shallow formations associated with oil and gas exploration and development in deep-water settings. Abnormal pore pressure can lead to water flow and gas and gas hydrate accumulations, which may affect drilling safety. Therefore, it is of great importance to accurately predict pore pressure in shallow deep-water formations. Experience over previous decades has shown, however, that there are not appropriate pressure calculation methods for these shallow formations. Pore pressure change is reflected closely in log data, particularly for mudstone formations. In this paper, pore pressure calculations for shallow formations are highlighted, and two concrete methods using log data are presented. The first method is modified from an E. Philips test in which a linear-exponential overburden pressure model is used. The second method is a new pore pressure method based on P-wave velocity that accounts for the effect of shallow gas and shallow water flow. Afterwards, the two methods are validated using case studies from two wells in the Yingqiong basin. Calculated results are compared with those obtained by the Eaton method, which demonstrates that the multi-regression method is more suitable for quick prediction of geological hazards in shallow layers.

A manic-depressive symptom self-report in optical scanable format.

PubMed

Glick, Henry A; McBride, Linda; Bauer, Mark S

2003-10-01

The Internal State Scale (ISS) is a self-report instrument that allows the simultaneous assessment of both manic and depressive symptoms in individuals with manic-depressive disorder. Prior work indicates that subscales are highly correlated with clinician ratings of mania and depression and provide a discriminant function that identifies individuals in manic/hypomanic, mixed, depressed, and euthymic mood states. A drawback to the ISS is that its items were developed in the visual analogue scale (VAS) format which is labor-intensive to score, particularly with repeat (e.g. daily) administration. A Likert-based format would allow quick and easy optical scanning for which scoring could be automated. To compare discriminating properties in Likert versus VAS format we re-analyzed previously collected data and collected new data: (a) VAS-based ISS scores from 86 subjects from a prior four-site study were re-analyzed by collapsing scores into 20 and then 10 Likert-based bins to assess loss of precision from collapsing scores, and (b) 24 additional subjects were administered the ISS in VAS and Likert formats to assess loss of precision due to instrument completion factors. Discriminant ability, including kappas and receiver operator characteristic curves, were unchanged across the two formats. Within-subjects reliability was uniformally high across formats. Likert-based scoring of the ISS can be used without loss of precision, thus making automated scoring of the ISS feasible. This format will be particularly useful for studies that require processing of large numbers of ISSs, such as those that collect frequent ratings over long periods of time and/or those that utilize large samples.

Stem Cell-Soluble Signals Enhance Multilumen Formation in SMG Cell Clusters.

PubMed

Maruyama, C L M; Leigh, N J; Nelson, J W; McCall, A D; Mellas, R E; Lei, P; Andreadis, S T; Baker, O J

2015-11-01

Saliva plays a major role in maintaining oral health. Patients with salivary hypofunction exhibit difficulty in chewing and swallowing foods, tooth decay, periodontal disease, and microbial infections. At this time, treatments for hyposalivation are limited to medications (e.g., muscarinic receptor agonists: pilocarpine and cevimeline) that induce saliva secretion from residual acinar cells as well as artificial salivary substitutes. Therefore, advancement of restorative treatments is necessary to improve the quality of life in these patients. Our previous studies indicated that salivary cells are able to form polarized 3-dimensional structures when grown on growth factor-reduced Matrigel. This basement membrane is rich in laminin-III (L1), which plays a critical role in salivary gland formation. Mitotically inactive feeder layers have been used previously to support the growth of many different cell types, as they provide factors necessary for cell growth and organization. The goal of this study was to improve salivary gland cell differentiation in primary cultures by using a combination of L1 and a feeder layer of human hair follicle-derived mesenchymal stem cells (hHF-MSCs). Our results indicated that the direct contact of mouse submandibular (mSMG) cell clusters and hHF-MSCs was not required for mSMG cells to form acinar and ductal structures. However, the hHF-MSC conditioned medium enhanced cell organization and multilumen formation, indicating that soluble signals secreted by hHF-MSCs play a role in promoting these features. © International & American Associations for Dental Research 2015.

Mechanisms of fine extinction band development in vein quartz: new insights from correlative light and electron microscopy

NASA Astrophysics Data System (ADS)

Derez, Tine; Van Der Donck, Tom; Plümper, Oliver; Muchez, Philippe; Pennock, Gill; Drury, Martyn R.; Sintubin, Manuel

2017-07-01

Fine extinction bands (FEBs) (also known as deformation lamellae) visible with polarized light microscopy in quartz consist of a range of nanostructures, inferring different formation processes. Previous transmission electron microscopy studies have shown that most FEB nanostructures in naturally deformed quartz are elongated subgrains formed by recovery of dislocation slip bands. Here we show that three types of FEB nanostructure occur in naturally deformed vein quartz from the low-grade metamorphic High-Ardenne slate belt (Belgium). Prismatic oriented FEBs are defined by bands of dislocation walls. Dauphiné twin boundaries present along the FEB boundaries probably formed after FEB formation. In an example of two sub-rhombohedral oriented FEBs, developed as two sets in one grain, the finer FEB set consists of elongated subgrains, similar to FEBs described in previous transmission electron microscopy studies. The second wider FEB set consists of bands with different dislocation density and fluid-inclusion content. The wider FEB set is interpreted as bands with different plastic strain associated with the primary growth banding of the vein quartz grain. The nanometre-scale fluid inclusions are interpreted to have formed from structurally bounded hydroxyl groups that moreover facilitated formation of the elongate subgrains. Larger fluid inclusions aligned along FEBs are explained by fluid-inclusion redistribution along dislocation cores. The prismatic FEB nanostructure and the relation between FEBs and growth bands have not been recognized before, although related structures have been reported in experimentally deformed quartz.

Immunomodulatory effects of amniotic membrane matrix incorporated into collagen scaffolds.

PubMed

Hortensius, Rebecca A; Ebens, Jill H; Harley, Brendan A C

2016-06-01

Adult tendon wound repair is characterized by the formation of disorganized collagen matrix which leads to decreases in mechanical properties and scar formation. Studies have linked this scar formation to the inflammatory phase of wound healing. Instructive biomaterials designed for tendon regeneration are often designed to provide both structural and cellular support. In order to facilitate regeneration, success may be found by tempering the body's inflammatory response. This work combines collagen-glycosaminoglycan scaffolds, previously developed for tissue regeneration, with matrix materials (hyaluronic acid and amniotic membrane) that have been shown to promote healing and decreased scar formation in skin studies. The results presented show that scaffolds containing amniotic membrane matrix have significantly increased mechanical properties and that tendon cells within these scaffolds have increased metabolic activity even when the media is supplemented with the pro-inflammatory cytokine interleukin-1 beta. Collagen scaffolds containing hyaluronic acid or amniotic membrane also temper the expression of genes associated with the inflammatory response in normal tendon healing (TNF-α, COLI, MMP-3). These results suggest that alterations to scaffold composition, to include matrix known to decrease scar formation in vivo, can modify the inflammatory response in tenocytes. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1332-1342, 2016. © 2016 Wiley Periodicals, Inc.

Formation and dissolution processes of the 6-thioguanine (6TG) self-assembled monolayer. A kinetic study.

PubMed

Madueño, Rafael; Pineda, Teresa; Sevilla, José Manuel; Blázquez, Manuel

2005-02-03

This is a report on the kinetics of the destruction and formation processes of the 6-thioguanine self-assembled monolayer (6TG SAM) on a mercury electrode from acid solutions by chronoamperometry. The destruction of the 6TG SAM that has been previously formed under open circuit potential conditions is carried out by stepping the potential from an initial value where the chemisorbed layer is stable up to potentials where the molecules are no longer chemisorbed. The destruction of the SAM has been described by a model that involves three types of contributions: (i) a Langmuir-type adsorption process, (ii) a 2D nucleation mechanism followed by a growth controlled by surface diffusion, and (iii) a 2D nucleation mechanism followed by a growth at a constant rate. The nonlinear fit of the experimental transients by using this procedure allows the quantitative determination of the individual contributions to the overall process. The kinetics of the formation process is studied under electrochemical conditions. The chronoamperometric experiment allows us to monitor the early stages of 6TG SAM formation. The implications of the physisorbed state at low potentials in the type of monolayer formation and destruction processes as well as the influence of temperature are also discussed.

RX J0848.6+4453: The evolution of galaxy sizes and stellar populations in A z = 1.27 cluster

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

Jørgensen, Inger; Chiboucas, Kristin; Schiavon, Ricardo P.

2014-12-01

RX J0848.6+4453 (Lynx W) at redshift 1.27 is part of the Lynx Supercluster of galaxies. We present an analysis of the stellar populations and star formation history for a sample of 24 members of the cluster. Our study is based on deep optical spectroscopy obtained with Gemini North combined with imaging data from Hubble Space Telescope. Focusing on the 13 bulge-dominated galaxies for which we can determine central velocity dispersions, we find that these show a smaller evolution with redshift of sizes and velocity dispersions than reported for field galaxies and galaxies in poorer clusters. Our data show that themore » galaxies in RX J0848.6+4453 populate the fundamental plane (FP) similar to that found for lower-redshift clusters. The zero-point offset for the FP is smaller than expected if the cluster's galaxies are to evolve passively through the location of the FP we established in our previous work for z = 0.8-0.9 cluster galaxies and then to the present-day FP. The FP zero point for RX J0848.6+4453 corresponds to an epoch of last star formation at z{sub form}=1.95{sub −0.15}{sup +0.22}. Further, we find that the spectra of the galaxies in RX J0848.6+4453 are dominated by young stellar populations at all galaxy masses and in many cases show emission indicating low-level ongoing star formation. The average age of the young stellar populations as estimated from the strength of the high-order Balmer line Hζ is consistent with a major star formation episode 1-2 Gyr prior, which in turn agrees with z {sub form} = 1.95. These galaxies dominated by young stellar populations are distributed throughout the cluster. We speculate that low-level star formation has not yet been fully quenched in the center of this cluster, possibly because the cluster is significantly poorer than other clusters previously studied at similar redshifts, which appear to have very little ongoing star formation in their centers. The mixture in RX J0848.6+4453 of passive galaxies with young stellar populations and massive galaxies still experiencing some star formation appears similar to the galaxy populations recently identified in two z ≈ 2 clusters.« less

Analysis of Geologic CO2 Sequestration at Farnham Dome, Utah, USA

NASA Astrophysics Data System (ADS)

Lee, S.; Han, W.; Morgan, C.; Lu, C.; Esser, R.; Thorne, D.; McPherson, B.

2008-12-01

The Farnham Dome in east-central Utah is an elongated, Laramide-age anticline along the northern plunge of the San Rafael uplift and the western edge of the Uinta Basin. We are helping design a proposed field demonstration of commercial-scale geologic CO2 sequestration, including injection of 2.9 million tons of CO2 over four years time. The Farnham Dome pilot site stratigraphy includes a stacked system of saline formations alternating with low-permeability units. Facilitating the potential sequestration demonstration is a natural CO2 reservoir at depth, the Jurassic-age Navajo formation, which contains an estimated 50 million tons of natural CO2. The sequestration test design includes two deep formations suitable for supercritical CO2 injection, the Jurassic-age Wingate sandstone and the Permian-age White Rim sandstone. We developed a site-specific geologic model based on available geophysical well logs and formation tops data for use with numerical simulation. The current geologic model is limited to an area of approximately 6.5x4.5 km2 and 2.5 km thick, which contains 12 stacked formations starting with the White Rim formation at the bottom (>5000 feet bgl) and extending to the Jurassic Curtis formation at the top of the model grid. With the detail of the geologic model, we are able to estimate the Farnham Dome CO2 capacity at approximately 36.5 million tones within a 5 mile radius of a single injection well. Numerical simulation of multiphase, non- isothermal CO2 injection and flow suggest that the injected CO2 plume will not intersect nearby fault zones mapped in previous geologic studies. Our simulations also examine and compare competing roles of different trapping mechanisms, including hydrostratigraphic, residual gas, solubility, and mineralization trapping. Previous studies of soil gas flux at the surface of the fault zones yield no significant evidence of CO2 leakage from the natural reservoir at Farnham Dome, and thus we use these simulations to evaluate what factors make this natural reservoir so effective for CO2 storage. Our characterization and simulation efforts are producing a CO2 sequestration framework that incorporates production and capacity estimation, area-of-review, injectivity, and trapping mechanisms. Likewise, mitigation and monitoring strategies have been formulated from the site characterization and modeling results.

Succession of structural events in the Goren greenstone belt (Burkina Faso): Implications for West African tectonics

NASA Astrophysics Data System (ADS)

Hein, Kim A. A.

2010-02-01

Ten years after field investigations in the SE Goren greenstone belt (GGB) of Burkina Faso by the Sanmatenga J.V., sponsored field studies conducted in 2007 have significantly enhanced structural datasets. The studies in 2007 were conducted across an expanded area of the GGB that included both southwestern and northeastern domains, and portions of the Pissila batholith to the west of the GGB. A revision of tectonic models proposed by Hein et al. [Hein, K.A.A., Morel, V., Kagoné, O., Kiemde, F., Mayes, K., 2004. Birimian lithological succession and structural evolution in the Goren Segment of the Boromo-Goren Greenstone Belt, Burkina Faso. Journal of African Earth Sciences 39, 1-23] is now possible. Three deformation events characterise the Goren greenstone belt. The deformation, D1 (previously D3) resulted in the formation of NW to NNW-trending steeply-dipping dextral-reverse shear zones folds and a penetrative S1-C schistosity that formed during a period of NE-SW shortening. The event is termed the Tangaean Event because it can be correlated across NE Burkina Faso in the Boromo, Bouroum, Yalago and Oudalan-Gorouol greenstone belts. The deformation, D2 (previously D2) resulted in the progressive development of NNE to NE-trending macroscopic to mesoscopic folds and a penetrative axial planar cleavage (S2), which was followed by the formation of dextral- and sinistral-reverse shears and a pervasive schistosity (S2-C). The first-order crustal-scale Sabce Shear Zone, which traverses the northern portion of the study area, is associated with macroscopic anticlockwise drag rotation of NW to NNW-trending D1 shears and folds: (the macroscopic fold was previously classified as D1). D2 in the GGB corresponds with the Eburnean Orogeny at 2130-1980 Ma, as described by [Feybesse, J.-L., Billa, M., Guerrot, C., Duguey, E., Lescuyer, J.-L, Milesi, J.-P., Bouchot, V., 2006, The paleoproterozoic Ghanian province: geodynamic model and ore controls, including regional stress modelling. Precambrian Research, 149-196]. The deformation D3 (previously D4) is recognised throughout the GGB. It is characterised by the formation of kinks and chevron folds (F3), or crenulation cleavage (S3) that are hosted by narrow WNW-trending shear zones. These formed during a period of north-south shortening termed the Wabo-Tampelse Event that post-dates the Eburnean Orogeny.

Water resources of Hot Springs County, Wyoming

USGS Publications Warehouse

Plafcan, Maria; Ogle, Kathy Muller

1994-01-01

The wells and springs inventoried in Hot Springs County most commonly had been completed in or issued from the Quaternary alluvium, Quaternary terrace deposits, Fort Union and Mesaverde Formations, Cody Shale, and the Frontier and Chugwater Formations. The largest discharges measured were from the Quaternary terrace deposits (400 gallons per minute) and the Phosphoria Formation (1,000 gallons per minute). Discharges from all other geologic units varied, but most wells and springs yielded 50 gallons per minute or less.Water-quality samples collected from springs that issued from the Absaroka Volcanic Supergroup, the Bighorn Dolomite, and the Flathead Sandstone had the lowest dissolved-solids concentrations, which ranged from 58 to 265 milligrams per liter, and the least variable water types. Water from the volcanic rocks was a sodium bicarbonate type; whereas, water from the Flathead Sandstone was a calcium bicarbonate type. Water types for all the other aquifers varied from sampling site to sampling site; however, water samples from the Fort Union Formation and the Cody Shale were consistently of the sodium sulfate type. The effect of oil- and gas-development at Hamilton Dome on thermal spring discharges at Hot Springs State Park near Thermopolis was studied. The estimated drawdown from 1918, when the Hamilton Dome oil field was discovered, to 1988 was made using drill-stem data from previous studies. Drawdown at Big Spring in the Park was estimated to be less than 3 feet on the basis of recent oil- and water-production data, previous modeling studies, and the estimated water-level drawdown of 330 feet in wells at the Hamilton Dome oil field.Streams originating in the Plains region of the county, such as Middle Fork Owl Creek, are ephemeral or intermittent; whereas, streams originating in the mountains, such as Gooseberry Creek, are perennial. Average annual runoff across the county ranges from 0.26 inches at a representative streamflow-gaging station near Worland in the plains region to 5.4 inches in the Owl Creek Mountains and southeastern Absaroka Range.

Effect of Fe 3+ concentration on MWCNTs formation in liquid arcing method

NASA Astrophysics Data System (ADS)

Shervin, Sh.; Gheytani, S.; Simchi, A.

2010-10-01

The formation of multi-walled carbon nanotubes (MWCNTs) during arc discharge in aqueous solutions of Fe 2(SO 4) 3 and FeCl 3 was studied. The concentration of iron ions changed from zero (deionized water) to 0.25 M and the cathodic products were examined by transmission electron microscopy, Raman spectrometry, and thermal gravimetric analysis. The experimental results showed that the crystallinity of MWCNTs is improved by increasing the concentration of iron ions. Nevertheless, the process yield and overall quality of the produced CNTs were significantly affected by iron concentration in the aqueous solution. This observation suggested that there should be an optimum iron concentration at which the formation of MWCNTs is favored. As compared with the sulfate solution, a higher process yield is obtained in the presence of chloride ions in agreement with previous reports.

Outcome dependency alters the neural substrates of impression formation

PubMed Central

Ames, Daniel L.; Fiske, Susan T.

2015-01-01

How do people maintain consistent impressions of other people when other people are often inconsistent? The present research addresses this question by combining recent neuroscientific insights with ecologically meaningful behavioral methods. Participants formed impressions of real people whom they met in a personally involving situation. fMRI and supporting behavioral data revealed that outcome dependency (i.e., depending on another person for a desired outcome) alters previously identified neural dynamics of impression formation. Consistent with past research, a functional localizer identified a region of dorsomedial PFC previously linked to social impression formation. In the main task, this ROI revealed the predicted patterns of activity across outcome dependency conditions: greater BOLD response when information confirmed (vs. violated) social expectations if participants were outcome-independent and the reverse pattern if participants were outcome-dependent. We suggest that, although social perceivers often discount expectancy-disconfirming information as noise, being dependent on another person for a desired outcome focuses impression-formation processing on the most diagnostic information, rather than on the most tractable information. PMID:23850465

Electrical Field Guided Electrospray Deposition for Production of Gradient Particle Patterns.

PubMed

Yan, Wei-Cheng; Xie, Jingwei; Wang, Chi-Hwa

2018-06-06

Our previous work demonstrated the uniform particle pattern formation on the substrates using electrical field guided electrospray deposition. In this work, we reported for the first time the fabrication of gradient particle patterns on glass slides using an additional point, line, or bar electrode based on our previous electrospray deposition configuration. We also demonstrated that the polydimethylsiloxane (PDMS) coating could result in the formation of uniform particle patterns instead of gradient particle patterns on glass slides using the same experimental setup. Meanwhile, we investigated the effect of experimental configurations on the gradient particle pattern formation by computational simulation. The simulation results are in line with experimental observations. The formation of gradient particle patterns was ascribed to the gradient of electric field and the corresponding focusing effect. Cell patterns can be formed on the particle patterns deposited on PDMS-coated glass slides. The formed particle patterns hold great promise for high-throughput screening of biomaterial-cell interactions and sensing.

Mechanical Model of Geometric Cell and Topological Algorithm for Cell Dynamics from Single-Cell to Formation of Monolayered Tissues with Pattern

PubMed Central

Kachalo, Sëma; Naveed, Hammad; Cao, Youfang; Zhao, Jieling; Liang, Jie

2015-01-01

Geometric and mechanical properties of individual cells and interactions among neighboring cells are the basis of formation of tissue patterns. Understanding the complex interplay of cells is essential for gaining insight into embryogenesis, tissue development, and other emerging behavior. Here we describe a cell model and an efficient geometric algorithm for studying the dynamic process of tissue formation in 2D (e.g. epithelial tissues). Our approach improves upon previous methods by incorporating properties of individual cells as well as detailed description of the dynamic growth process, with all topological changes accounted for. Cell size, shape, and division plane orientation are modeled realistically. In addition, cell birth, cell growth, cell shrinkage, cell death, cell division, cell collision, and cell rearrangements are now fully accounted for. Different models of cell-cell interactions, such as lateral inhibition during the process of growth, can be studied in detail. Cellular pattern formation for monolayered tissues from arbitrary initial conditions, including that of a single cell, can also be studied in detail. Computational efficiency is achieved through the employment of a special data structure that ensures access to neighboring cells in constant time, without additional space requirement. We have successfully generated tissues consisting of more than 20,000 cells starting from 2 cells within 1 hour. We show that our model can be used to study embryogenesis, tissue fusion, and cell apoptosis. We give detailed study of the classical developmental process of bristle formation on the epidermis of D. melanogaster and the fundamental problem of homeostatic size control in epithelial tissues. Simulation results reveal significant roles of solubility of secreted factors in both the bristle formation and the homeostatic control of tissue size. Our method can be used to study broad problems in monolayered tissue formation. Our software is publicly available. PMID:25974182

Mineral Trends in Early Hesperian Lacustrine Mudstone at Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Rampe, E. B.; Ming, D. W.; Grotzinger, J. P.; Morris, R. V.; Blake, D. F.; Vaniman, D. T.; Bristow, T. F.; Morrison, S. M.; Yen, A. S.; Chipera, S. J.;

A Comparative Observational Study of YSO Classification in Four Small Star-forming H ii Regions

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

Kang, Sung-Ju; Choi, Minho; Kang, Miju

We have developed a new young stellar object (YSO) identification and classification technique using mid-infrared Wide-field Infrared Survey Explorer (WISE) data. We compare this new technique with previous WISE YSO detection and classification methods that used either infrared colors or spectral energy distribution slopes. In this study, we also use the new technique to detect and examine the YSO population associated with four small H ii regions: KR 7, KR 81, KR 120, and KR 140. The relatively simple structure of these regions allows us to effectively use both spatial and temporal constraints to identify YSOs that are potential productsmore » of triggered star formation. We are also able to identify regions of active star formation around these H ii regions that are clearly not influenced by the H ii region expansion, and thus demonstrate that star formation is on-going on megayear timescales in some of these molecular clouds.« less

Ubiquitin chain specificities of E6AP E3 ligase and its HECT domain.

PubMed

Kobayashi, Fuminori; Nishiuchi, Takumi; Takaki, Kento; Konno, Hiroki

2018-02-05

Ubiquitination of target proteins is accomplished by isopeptide bond formation between the carboxy group of the C-terminal glycine (Gly) residue of ubiquitin (Ub) and the ɛ-amino group of lysine (Lys) on the target proteins. The formation of an isopeptide bond between Ubs that gives rise to a poly-Ub chain on the target proteins and the types of poly-Ub chains formed depend on which of the seven Lys residues or N-terminal methionine (Met) residue on Ub is used for chain elongation. To understand the linkage specificity mechanism of Ub chains on E3, the previous study established an assay to monitor the formation of a free diubiquitin chain (Ub 2 chain synthesis assay) by HECT type E3 ligase. In this study, we investigated Ub 2 chain specificity using E6AP HECT domain. We here demonstrate the importance of the N-terminal domain of full length E6AP for Ub 2 chain specificity. Copyright © 2017 Elsevier Inc. All rights reserved.

GABA promotes elastin synthesis and elastin fiber formation in normal human dermal fibroblasts (HDFs).

PubMed

Uehara, Eriko; Hokazono, Hideki; Hida, Mariko; Sasaki, Takako; Yoshioka, Hidekatsu; Matsuo, Noritaka

2017-06-01

The multiple physiological effects of γ-aminobutyric acid (GABA) as a functional food component have been recently reported. We previously reported that GABA upregulated the expression of type I collagen in human dermal fibroblasts (HDFs), and that oral administration of GABA significantly increased skin elasticity. However, details of the regulatory mechanism still remain unknown. In this study, we further examined the effects of GABA on elastin synthesis and elastin fiber formation in HDFs. Real-time PCR indicated that GABA significantly increased the expression of tropoelastin transcript in a dose-dependent manner. Additionally, the expression of fibrillin-1, fibrillin-2, and fibulin-5/DANCE, but not lysyl oxidase and latent transforming factor-β-binding protein 4, were also significantly increased in HDFs. Finally, immunohistochemical analysis confirmed that treatment with GABA dramatically increased the formation of elastic fibers in HDFs. Taken together, our results showed that GABA improves skin elasticity in HDFs by upregulating elastin synthesis and elastin fiber formation.

Monitoring Ion Track Formation Using In Situ RBS/c, ToF-ERDA, and HR-PIXE.

PubMed

Karlušić, Marko; Fazinić, Stjepko; Siketić, Zdravko; Tadić, Tonči; Cosic, Donny Domagoj; Božičević-Mihalić, Iva; Zamboni, Ivana; Jakšić, Milko; Schleberger, Marika

2017-09-06

The aim of this work is to investigate the feasibility of ion beam analysis techniques for monitoring swift heavy ion track formation. First, the use of the in situ Rutherford backscattering spectrometry in channeling mode to observe damage build-up in quartz SiO₂ after MeV heavy ion irradiation is demonstrated. Second, new results of the in situ grazing incidence time-of-flight elastic recoil detection analysis used for monitoring the surface elemental composition during ion tracks formation in various materials are presented. Ion tracks were found on SrTiO₃, quartz SiO₂, a-SiO₂, and muscovite mica surfaces by atomic force microscopy, but in contrast to our previous studies on GaN and TiO₂, surface stoichiometry remained unchanged. Third, the usability of high resolution particle induced X-ray spectroscopy for observation of electronic dynamics during early stages of ion track formation is shown.

NF-κB inhibitors that prevent foam cell formation and atherosclerotic plaque accumulation.

PubMed

Plotkin, Jesse D; Elias, Michael G; Dellinger, Anthony L; Kepley, Christopher L

2017-08-01

The transformation of monocyte-derived macrophages into lipid-laden foam cells is one inflammatory process underlying atherosclerotic disease. Previous studies have demonstrated that fullerene derivatives (FDs) have inflammation-blunting properties. Thus, it was hypothesized that FD could inhibit the transformation process underlying foam cell formation. Fullerene derivatives inhibited the phorbol myristic acid/oxidized low-density lipoprotein-induced differentiation of macrophages into foam cells as determined by lipid staining and morphology.Lipoprotein-induced generation of TNF-α, C5a-induced MC activation, ICAM-1 driven adhesion, and CD36 expression were significantly inhibited in FD treated cells compared to non-treated cells. Inhibition appeared to be mediated through the NF-κB pathway as FD reduced expression of NF-κB and atherosclerosis-associated genes. Compared to controls, FD dramatically inhibited plaque formation in arteries of apolipoprotein E null mice. Thus, FD may be an unrecognized therapy to prevent atherosclerotic lesions via inhibition of foam cell formation and MC stabilization. Copyright © 2017 Elsevier Inc. All rights reserved.

G protein-coupled receptor internalization assays in the high-content screening format.

PubMed

Haasen, Dorothea; Schnapp, Andreas; Valler, Martin J; Heilker, Ralf

2006-01-01

High-content screening (HCS), a combination of fluorescence microscopic imaging and automated image analysis, has become a frequently applied tool to study test compound effects in cellular disease-modeling systems. This chapter describes the measurement of G protein-coupled receptor (GPCR) internalization in the HCS format using a high-throughput, confocal cellular imaging device. GPCRs are the most successful group of therapeutic targets on the pharmaceutical market. Accordingly, the search for compounds that interfere with GPCR function in a specific and selective way is a major focus of the pharmaceutical industry today. This chapter describes methods for the ligand-induced internalization of GPCRs labeled previously with either a fluorophore-conjugated ligand or an antibody directed against an N-terminal tag of the GPCR. Both labeling techniques produce robust assay formats. Complementary to other functional GPCR drug discovery assays, internalization assays enable a pharmacological analysis of test compounds. We conclude that GPCR internalization assays represent a valuable medium/high-throughput screening format to determine the cellular activity of GPCR ligands.

Ferulic acid destabilizes preformed {beta}-amyloid fibrils in vitro

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

Ono, Kenjiro; Hirohata, Mie; Yamada, Masahito

2005-10-21

Inhibition of the formation of {beta}-amyloid fibrils (fA{beta}), as well as the destabilization of preformed fA{beta} in the CNS, would be attractive therapeutic targets for the treatment of Alzheimer's disease (AD). We reported previously that curcumin (Cur) inhibits fA{beta} formation from A{beta} and destabilizes preformed fA{beta} in vitro. Using fluorescence spectroscopic analysis with thioflavin T and electron microscopic studies, we examined the effects of ferulic acid (FA) on the formation, extension, and destabilization of fA{beta} at pH 7.5 at 37 deg C in vitro. We next compared the anti-amyloidogenic activities of FA with Cur, rifampicin, and tetracycline. Ferulic acid dose-dependentlymore » inhibited fA{beta} formation from amyloid {beta}-peptide, as well as their extension. Moreover, it destabilized preformed fA{beta}s. The overall activity of the molecules examined was in the order of: Cur > FA > rifampicin = tetracycline. FA could be a key molecule for the development of therapeutics for AD.« less

Vortex formation through inertial wave focusing

NASA Astrophysics Data System (ADS)

Duran-Matute, Matias; Flor, Jan-Bert; Godeferd, Fabien

2011-11-01

We present a novel experimental and numerical study on the formation of columnar vortical structures by inertial waves in a rotating fluid. Two inertial-wave cones are generated by a vertically oscillating torus in a fluid in solid body rotation At the tip of the cones, there is a singular point towards which the energy of the waves gets focused. The particularity of this configuration, as compared to those of previous experiments (e.g. oscillating sphere or disc), is that the singular point's position within the fluid leads to complex non-linear wave interaction, which may lead to the formation of a localized vortex that expands in the vertical in the form of a Taylor column. Using detailed PIV measurements we consider the flow evolution from the localized wave overturning motion to the Taylor column formation as well as the inertial wave dynamics during this process, The results are discussed in the context of turbulence in rotating fluids. We acknowledge financial support from projects ANR ANISO and CIBLE.

Monitoring Ion Track Formation Using In Situ RBS/c, ToF-ERDA, and HR-PIXE

PubMed Central

Karlušić, Marko; Fazinić, Stjepko; Siketić, Zdravko; Tadić, Tonči; Cosic, Donny Domagoj; Božičević-Mihalić, Iva; Zamboni, Ivana; Jakšić, Milko; Schleberger, Marika

2017-01-01

The aim of this work is to investigate the feasibility of ion beam analysis techniques for monitoring swift heavy ion track formation. First, the use of the in situ Rutherford backscattering spectrometry in channeling mode to observe damage build-up in quartz SiO2 after MeV heavy ion irradiation is demonstrated. Second, new results of the in situ grazing incidence time-of-flight elastic recoil detection analysis used for monitoring the surface elemental composition during ion tracks formation in various materials are presented. Ion tracks were found on SrTiO3, quartz SiO2, a-SiO2, and muscovite mica surfaces by atomic force microscopy, but in contrast to our previous studies on GaN and TiO2, surface stoichiometry remained unchanged. Third, the usability of high resolution particle induced X-ray spectroscopy for observation of electronic dynamics during early stages of ion track formation is shown. PMID:28878186

Integrating fluid dynamic and biologic effects on staphylococci bacteria biofilms

NASA Astrophysics Data System (ADS)

Sherman, Erica; Endres, Jennifer; Bayles, Kenneth; Wei, Timothy

2017-11-01

Staphylococcus aureus bacteria are able to form biofilms and distinctive tower structures that facilitate their ability to tolerate treatment and to spread within the human body. The formation of towers, which break off, get carried downstream and serve to initiate biofilms in other parts of the body are of particular interest here. In previous work on biofilm growth and evolution in steady, laminar microchannel flows, it has been established that tower formation occurs around a very limited range of applied shear stresses centered on 0.6 dynes/cm2. Quantifying cell density characteristics as a function of time during biofilm formation reveals indicators of tower development hours before towers actually form and become visible. The next step in this research is to explore biological factors that might explain why this specific shear is so important. Additional studies with mutants, e.g. ica-A, that have been tied to tower formation have been conducted. The shear dependence of these mutants and their correlation to the behavior of wild type S. aureus is examined.

Mechanism of IAPP amyloid fibril formation involves an intermediate with a transient β-sheet

PubMed Central

Buchanan, Lauren E.; Dunkelberger, Emily B.; Tran, Huong Q.; Cheng, Pin-Nan; Chiu, Chi-Cheng; Cao, Ping; Raleigh, Daniel P.; de Pablo, Juan J.; Nowick, James S.; Zanni, Martin T.

2013-01-01

Amyloid formation is implicated in more than 20 human diseases, yet the mechanism by which fibrils form is not well understood. We use 2D infrared spectroscopy and isotope labeling to monitor the kinetics of fibril formation by human islet amyloid polypeptide (hIAPP or amylin) that is associated with type 2 diabetes. We find that an oligomeric intermediate forms during the lag phase with parallel β-sheet structure in a region that is ultimately a partially disordered loop in the fibril. We confirm the presence of this intermediate, using a set of homologous macrocyclic peptides designed to recognize β-sheets. Mutations and molecular dynamics simulations indicate that the intermediate is on pathway. Disrupting the oligomeric β-sheet to form the partially disordered loop of the fibrils creates a free energy barrier that is the origin of the lag phase during aggregation. These results help rationalize a wide range of previous fragment and mutation studies including mutations in other species that prevent the formation of amyloid plaques. PMID:24218609

Co-transcriptional formation of DNA:RNA hybrid G-quadruplex and potential function as constitutional cis element for transcription control.

PubMed

Zheng, Ke-wei; Xiao, Shan; Liu, Jia-quan; Zhang, Jia-yu; Hao, Yu-hua; Tan, Zheng

2013-05-01

G-quadruplex formation in genomic DNA is considered to regulate transcription. Previous investigations almost exclusively focused on intramolecular G-quadruplexes formed by DNA carrying four or more G-tracts, and structure formation has rarely been studied in physiologically relevant processes. Here, we report an almost entirely neglected, but actually much more prevalent form of G-quadruplexes, DNA:RNA hybrid G-quadruplexes (HQ) that forms in transcription. HQ formation requires as few as two G-tracts instead of four on a non-template DNA strand. Potential HQ sequences (PHQS) are present in >97% of human genes, with an average of 73 PHQSs per gene. HQ modulates transcription under both in vitro and in vivo conditions. Transcriptomal analysis of human tissues implies that maximal gene expression may be limited by the number of PHQS in genes. These features suggest that HQs may play fundamental roles in transcription regulation and other transcription-mediated processes.

Inhibition of Steptococcus mutans biofilm formation by extracts of Tenacibaculum sp. 20J, a bacterium with wide-spectrum quorum quenching activity.

PubMed

Muras, Andrea; Mayer, Celia; Romero, Manuel; Camino, Tamara; Ferrer, Maria D; Mira, Alex; Otero, Ana

2018-01-01

Background : Previous studies have suggested the quorum sensing signal AI-2 as a potential target to prevent the biofilm formation by Streptococcus mutans , a pathogen involved in tooth decay. Objective : To obtain inhibition of biofilm formation by S. mutans by extracts obtained from the marine bacterium Tenacibaculum sp. 20J interfering with the AI-2 quorum sensing system. Design : The AI-2 inhibitory activity was tested with the biosensors Vibrio harveyi BB170 and JMH597. S. mutans ATCC25175 biofilm formation was monitored using impedance real-time measurements with the xCELLigence system®, confocal laser microscopy, and the crystal violet quantification method. Results : The addition of the cell extract from Tenacibaculum sp. 20J reduced biofilm formation in S. mutans ATCC25175 by 40-50% compared to the control without significantly affecting growth. A decrease of almost 40% was also observed in S. oralis DSM20627 and S. dentisani 7747 biofilms. Conclusions : The ability of Tenacibaculum sp. 20J to interfere with AI-2 and inhibit biofilm formation in S. mutans was demonstrated. The results indicate that the inhibition of quorum sensing processes may constitute a suitable strategy for inhibiting dental plaque formation, although additional experiments using mixed biofilm models would be required.

Inhibition of Steptococcus mutans biofilm formation by extracts of Tenacibaculum sp. 20J, a bacterium with wide-spectrum quorum quenching activity

PubMed Central

Muras, Andrea; Mayer, Celia; Romero, Manuel; Camino, Tamara; Ferrer, Maria D.; Mira, Alex; Otero, Ana

2018-01-01

ABSTRACT Background: Previous studies have suggested the quorum sensing signal AI-2 as a potential target to prevent the biofilm formation by Streptococcus mutans, a pathogen involved in tooth decay. Objective: To obtain inhibition of biofilm formation by S. mutans by extracts obtained from the marine bacterium Tenacibaculum sp. 20J interfering with the AI-2 quorum sensing system. Design: The AI-2 inhibitory activity was tested with the biosensors Vibrio harveyi BB170 and JMH597. S. mutans ATCC25175 biofilm formation was monitored using impedance real-time measurements with the xCELLigence system®, confocal laser microscopy, and the crystal violet quantification method. Results: The addition of the cell extract from Tenacibaculum sp. 20J reduced biofilm formation in S. mutans ATCC25175 by 40–50% compared to the control without significantly affecting growth. A decrease of almost 40% was also observed in S. oralis DSM20627 and S. dentisani 7747 biofilms. Conclusions: The ability of Tenacibaculum sp. 20J to interfere with AI-2 and inhibit biofilm formation in S. mutans was demonstrated. The results indicate that the inhibition of quorum sensing processes may constitute a suitable strategy for inhibiting dental plaque formation, although additional experiments using mixed biofilm models would be required. PMID:29410771

Bridge-bonded formate: active intermediate or spectator species in formic acid oxidation on a Pt film electrode?

PubMed

Chen, Y-X; Heinen, M; Jusys, Z; Behm, R J

2006-12-05

We present and discuss the results of an in situ IR study on the mechanism and kinetics of formic acid oxidation on a Pt film/Si electrode, performed in an attenuated total reflection (ATR) flow cell configuration under controlled mass transport conditions, which specifically aimed at elucidating the role of the adsorbed bridge-bonded formates in this reaction. Potentiodynamic measurements show a complex interplay between formation and desorption/oxidation of COad and formate species and the total Faradaic current. The notably faster increase of the Faradaic current compared to the coverage of bridge-bonded formate in transient measurements at constant potential, but with different formic acid concentrations, reveals that adsorbed formate decomposition is not rate-limiting in the dominant reaction pathway. If being reactive intermediate at all, the contribution of formate adsorption/decomposition to the reaction current decreases with increasing formic acid concentration, accounting for at most 15% for 0.2 M DCOOH at 0.7 VRHE. The rapid build-up/removal of the formate adlayer and its similarity with acetate or (bi-)sulfate adsorption/desorption indicate that the formate adlayer coverage is dominated by a fast dynamic adsorption-desorption equilibrium with the electrolyte, and that formate desorption is much faster than its decomposition. The results corroborate the proposal of a triple pathway reaction mechanism including an indirect pathway, a formate pathway, and a dominant direct pathway, as presented previously (Chen, Y. X.; et al. Angew. Chem. Int. Ed. 2006, 45, 981), in which adsorbed formates act as a site-blocking spectator in the dominant pathway rather than as an active intermediate.

The Effect of a Poster, Display, and Recommended Listening List on the Circulation of Audiobooks in the Public Library.

ERIC Educational Resources Information Center

Kucalaba, Linda

Previous studies have found that the librarian's use of book displays and recommended lists are an effective means to increase circulation in the public library. Yet conflicting results were found when these merchandising techniques were used with collection materials in the nonprint format, specifically audiobooks and videos, instead of books.…

Revealing the Mind of the Sage: The Narrative Rhetoric of the "Chuang Tzu."

ERIC Educational Resources Information Center

Kirkwood, William G.

1992-01-01

Argues that one of the formative texts of Taoism, the "Chuang Tzu," is worthy of study by rhetoric scholars because it reveals a unique approach to rhetoric in its attempt to disclose the mind of the sage not through logic but through intuition, and it shows how storytelling can acquaint people with previously unsuspected possibilities of thought…

Synthesis of Tetra-Functional Cubane Derivatives

DTIC Science & Technology

1992-11-30

1 ,5-Bis(p-toluenesulfonyl)-3,7-dihydroxyoctahydro-- 1,5-diazocine by Pyridinium Chlorochromate (POC). .. ...... 30 REFERENCES...ditosyldiazocine was studied. Previously, oxidation with CrO3/pyridine resulted in the formation of hemiketal. Recently, pyridinium chlorochromate (PCC) in...1,5- diazocine by Pyridinium Chlorochromate (PCC). A solution of the dihydroxydi- azocine (0.05 mole) in 20 mL of dichloromethane was then added in

VdCYC8, encoding CYC8 glucose repression mediator protein, is required for microsclerotia formation and full virulence in Verticillium dahliae

USDA-ARS?s Scientific Manuscript database

Verticillium dahliae is the primary causal agent for Verticillium wilt disease on a diverse array of economically important crops, including cotton. In previous research, we screened a T-DNA insertional mutant library of the highly virulent isolate Vd080 derived from cotton. In this study, the targ...

Virtual Ray Tracing as a Conceptual Tool for Image Formation in Mirrors and Lenses

ERIC Educational Resources Information Center

Heikkinen, Lasse; Savinainen, Antti; Saarelainen, Markku

2016-01-01

The ray tracing method is widely used in teaching geometrical optics at the upper secondary and university levels. However, using simple and straightforward examples may lead to a situation in which students use the model of ray tracing too narrowly. Previous studies show that students seem to use the ray tracing method too concretely instead of…

The Identification of Reasons, Solutions, and Techniques Informing a Theory-Based Intervention Targeting Recreational Sports Participation

ERIC Educational Resources Information Center

St Quinton, Tom; Brunton, Julie A.

2018-01-01

Purpose: This study is the 3rd piece of formative research utilizing the theory of planned behavior to inform the development of a behavior change intervention. Focus groups were used to identify reasons for and solutions to previously identified key beliefs in addition to potentially effective behavior change techniques. Method: A purposive…

Navigating the "New" Marriage Market: How Attitudes toward Partner Characteristics Shape Union Formation

ERIC Educational Resources Information Center

Goldscheider, Frances; Kaufman, Gayle; Sassler, Sharon

2009-01-01

Trends in divorce and nonmarital childbearing suggest that the marriage market is increasingly filled with people who have been married and/or have children. This study examines the effect of personal attitudes on entrance into a union with a partner who has been previously married or has children. Using data from two waves of the National Survey…

Grammatical Morphology in Monolingual and Bilingual Children with and without Language Impairment: The Case of Dutch Plurals and Past Participles

ERIC Educational Resources Information Center

Boerma, Tessel; Wijnen, Frank; Leseman, Paul; Blom, Elma

2017-01-01

Purpose: Grammatical morphology is often a locus of difficulty for both children with language impairment (LI) and bilingual children. In contrast to previous research that mainly focused on verbal tense and agreement markings, the present study investigated whether plural and past participle formation can disentangle the effects of LI and…

Effect of circadian phase on memory acquisition and recall: operant conditioning vs. classical conditioning.

PubMed

Garren, Madeleine V; Sexauer, Stephen B; Page, Terry L

2013-01-01

There have been several studies on the role of circadian clocks in the regulation of associative learning and memory processes in both vertebrate and invertebrate species. The results have been quite variable and at present it is unclear to what extent the variability observed reflects species differences or differences in methodology. Previous results have shown that following differential classical conditioning in the cockroach, Rhyparobia maderae, in an olfactory discrimination task, formation of the short-term and long-term memory is under strict circadian control. In contrast, there appeared to be no circadian regulation of the ability to recall established memories. In the present study, we show that following operant conditioning of the same species in a very similar olfactory discrimination task, there is no impact of the circadian system on either short-term or long-term memory formation. On the other hand, ability to recall established memories is strongly tied to the circadian phase of training. On the basis of these data and those previously reported for phylogenetically diverse species, it is suggested that there may be fundamental differences in the way the circadian system regulates learning and memory in classical and operant conditioning.

Effect of Circadian Phase on Memory Acquisition and Recall: Operant Conditioning vs. Classical Conditioning

PubMed Central

Garren, Madeleine V.; Sexauer, Stephen B.; Page, Terry L.

2013-01-01

There have been several studies on the role of circadian clocks in the regulation of associative learning and memory processes in both vertebrate and invertebrate species. The results have been quite variable and at present it is unclear to what extent the variability observed reflects species differences or differences in methodology. Previous results have shown that following differential classical conditioning in the cockroach, Rhyparobia maderae, in an olfactory discrimination task, formation of the short-term and long-term memory is under strict circadian control. In contrast, there appeared to be no circadian regulation of the ability to recall established memories. In the present study, we show that following operant conditioning of the same species in a very similar olfactory discrimination task, there is no impact of the circadian system on either short-term or long-term memory formation. On the other hand, ability to recall established memories is strongly tied to the circadian phase of training. On the basis of these data and those previously reported for phylogenetically diverse species, it is suggested that there may be fundamental differences in the way the circadian system regulates learning and memory in classical and operant conditioning. PMID:23533587

Multiple Roles of Integrin-Linked Kinase in Epidermal Development, Maturation and Pigmentation Revealed by Molecular Profiling

PubMed Central

Judah, David; Rudkouskaya, Alena; Wilson, Ryan; Carter, David E.; Dagnino, Lina

2012-01-01

Integrin-linked kinase (ILK) is an important scaffold protein that mediates a variety of cellular responses to integrin stimulation by extracellular matrix proteins. Mice with epidermis-restricted inactivation of the Ilk gene exhibit pleiotropic phenotypic defects, including impaired hair follicle morphogenesis, reduced epidermal adhesion to the basement membrane, compromised epidermal integrity, as well as wasting and failure to thrive leading to perinatal death. To better understand the underlying molecular mechanisms that cause such a broad range of alterations, we investigated the impact of Ilk gene inactivation on the epidermis transcriptome. Microarray analysis showed over 700 differentially regulated mRNAs encoding proteins involved in multiple aspects of epidermal function, including keratinocyte differentiation and barrier formation, inflammation, regeneration after injury, and fundamental epidermal developmental pathways. These studies also revealed potential effects on genes not previously implicated in ILK functions, including those important for melanocyte and melanoblast development and function, regulation of cytoskeletal dynamics, and homeobox genes. This study shows that ILK is a critical regulator of multiple aspects of epidermal function and homeostasis, and reveals the previously unreported involvement of ILK not only in epidermal differentiation and barrier formation, but also in melanocyte genesis and function. PMID:22574216

Multiple roles of integrin-linked kinase in epidermal development, maturation and pigmentation revealed by molecular profiling.

PubMed

Judah, David; Rudkouskaya, Alena; Wilson, Ryan; Carter, David E; Dagnino, Lina

2012-01-01

Integrin-linked kinase (ILK) is an important scaffold protein that mediates a variety of cellular responses to integrin stimulation by extracellular matrix proteins. Mice with epidermis-restricted inactivation of the Ilk gene exhibit pleiotropic phenotypic defects, including impaired hair follicle morphogenesis, reduced epidermal adhesion to the basement membrane, compromised epidermal integrity, as well as wasting and failure to thrive leading to perinatal death. To better understand the underlying molecular mechanisms that cause such a broad range of alterations, we investigated the impact of Ilk gene inactivation on the epidermis transcriptome. Microarray analysis showed over 700 differentially regulated mRNAs encoding proteins involved in multiple aspects of epidermal function, including keratinocyte differentiation and barrier formation, inflammation, regeneration after injury, and fundamental epidermal developmental pathways. These studies also revealed potential effects on genes not previously implicated in ILK functions, including those important for melanocyte and melanoblast development and function, regulation of cytoskeletal dynamics, and homeobox genes. This study shows that ILK is a critical regulator of multiple aspects of epidermal function and homeostasis, and reveals the previously unreported involvement of ILK not only in epidermal differentiation and barrier formation, but also in melanocyte genesis and function.

New age constraints on the palaeoenvironmental evolution of the late Paleozoic back-arc basin along the western Gondwana margin of southern Peru

NASA Astrophysics Data System (ADS)

Boekhout, F.; Reitsma, M. J.; Spikings, R.; Rodriguez, R.; Ulianov, A.; Gerdes, A.; Schaltegger, U.

2018-03-01

The tectonic evolution of the western Gondwana margin during Pangaea amalgation is recorded in variations in the Permo-Carboniferous back-arc basin sedimentation of Peru. This study provides the first radiometric age constraints on the volcanic and sedimentary sequences of south-central eastern Peru up to the western-most tip of Bolivia, and now permits the correlation of lateral facies variations to the late Paleozoic pre-Andean orogenic cycle. The two phases of Gondwanide magmatism and metamorphism at c. 315 Ma and c. 260 Ma are reflected in two major changes in this sedimentary environment. Our detrital U-Pb zircon ages demonstrate that the timing of Ambo Formation deposition corroborates the Late Mississipian age estimates. The transition from the Ambo to the Tarma Formation around the Middle Pennsylvanian Early Gondwanide Orogeny (c. 315 Ma) represents a relative deepening of the basin. Throughout the shallow marine deposits of the Tarma Formation evidence for contemporaneous volcanism becomes gradually more pronounced and culminates around 312 - 309 Ma. Continuous basin subsidence resulted in a buildup of platform carbonates of the Copacabana Formation. Our data highlights the presence of a previously unrecognized phase of deposition of mainly fluvial sandstones and localized volcanism (281-270 Ma), which we named ´Oqoruro Formation'. This sedimentary succession was previously miss-assigned to the so-called Mitu Group, which has recently been dated to start deposition in the Middle Triassic (∼245-240 Ma). The emersion of this marine basin coincides with the onset of a major plutonic pulse related to the Late Gondwanide Orogeny (c. 260). Exhumation lead to the consequent retreat of the epeiric sea to the present-day sub-Andean region, and the coeval accumulation of the fluvial Oqoruro Formation in south eastern Peru. These late Paleozoic palaeoenvironmental changes in the back-arc basins along the western Gondwana margin of southern reflect changes in tectonic plate reorganization in a long-lived Paleozoic accretionary orogeny.

Reactive Desorption and Radiative Association as Possible Drivers of Complex Molecule Formation in the Cold Interstellar Medium

NASA Astrophysics Data System (ADS)

Vasyunin, A. I.; Herbst, Eric

2013-05-01

The recent discovery of terrestrial-type organic species such as methyl formate and dimethyl ether in the cold interstellar gas has proved that the formation of organic matter in the Galaxy begins at a much earlier stage of star formation than was previously thought. This discovery represents a challenge for astrochemical modelers. The abundances of these molecules cannot be explained by the previously developed "warm-up" scenario, in which organic molecules are formed via diffusive chemistry on surfaces of interstellar grains starting at 30 K, and then released to the gas at higher temperatures during later stages of star formation. In this article, we investigate an alternative scenario in which complex organic species are formed via a sequence of gas-phase reactions between precursor species formed on grain surfaces and then ejected into the gas via efficient reactive desorption, a process in which non-thermal desorption occurs as a result of conversion of the exothermicity of chemical reactions into the ejection of products from the surface. The proposed scenario leads to reasonable if somewhat mixed results at temperatures as low as 10 K and may be considered as a step toward the explanation of abundances of terrestrial-like organic species observed during the earliest stages of star formation.

Modeling of the cranking and charging processes of conventional valve regulated lead acid (VRLA) batteries in micro-hybrid applications

NASA Astrophysics Data System (ADS)

Gou, Jun; Lee, Anson; Pyko, Jan

2014-10-01

The cranking and charging processes of a VRLA battery during stop-start cycling in micro-hybrid applications were simulated by one dimensional mathematical modeling, to study the formation and distribution of lead sulfate across the cell and analyze the resulting effect on battery aging. The battery focused on in this study represents a conventional VRLA battery without any carbon additives in the electrodes or carbon-based electrodes. The modeling results were validated against experimental data and used to analyze the "sulfation" of negative electrodes - the common failure mode of lead acid batteries under high-rate partial state of charge (HRPSoC) cycling. The analyses were based on two aging mechanisms proposed in previous studies and the predictions showed consistency with the previous teardown observations that the sulfate formed at the negative interface is more difficult to be converted back than anywhere else in the electrodes. The impact of cranking pulses during stop-start cycling on current density and the corresponding sulfate layer production was estimated. The effects of some critical design parameters on sulfate formation, distribution and aging over cycling were investigated, which provided guidelines for developing models and designing of VRLA batteries in micro-hybrid applications.

Microstructure-sensitive small fatigue crack growth assessment. Effect of strain ratio multiaxial strain state and geometric discontinuities

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

Castelluccio, Gustavo M.; McDowell, David L.

Fatigue crack initiation in the high cycle fatigue regime is strongly influenced by microstructural features. Research efforts have usually focused on predicting fatigue resistance against crack incubation without considering the early fatigue crack growth after encountering the first grain boundary. However, a significant fraction of the variability of the total fatigue life can be attributed to growth of small cracks as they encounter the first few grain boundaries, rather than crack formation within the first grain. Our paper builds on the framework previously developed by the authors to assess microstructure-sensitive small fatigue crack formation and early growth under complex loadingmore » conditions. Moreover, the scheme employs finite element simulations that explicitly render grains and crystallographic directions along with simulation of microstructurally small fatigue crack growth from grain to grain. The methodology employs a crystal plasticity algorithm in ABAQUS that was previously calibrated to study fatigue crack initiation in RR1000 Ni-base superalloy. Our work present simulations with non-zero applied mean strains and geometric discontinuities that were not previously considered for calibration. Results exhibit trends similar to those found in experiments for multiple metallic materials, conveying a consistent physical description of fatigue damage phenomena.« less

Microstructure-sensitive small fatigue crack growth assessment. Effect of strain ratio multiaxial strain state and geometric discontinuities

DOE PAGES

Castelluccio, Gustavo M.; McDowell, David L.

2015-09-16

Fatigue crack initiation in the high cycle fatigue regime is strongly influenced by microstructural features. Research efforts have usually focused on predicting fatigue resistance against crack incubation without considering the early fatigue crack growth after encountering the first grain boundary. However, a significant fraction of the variability of the total fatigue life can be attributed to growth of small cracks as they encounter the first few grain boundaries, rather than crack formation within the first grain. Our paper builds on the framework previously developed by the authors to assess microstructure-sensitive small fatigue crack formation and early growth under complex loadingmore » conditions. Moreover, the scheme employs finite element simulations that explicitly render grains and crystallographic directions along with simulation of microstructurally small fatigue crack growth from grain to grain. The methodology employs a crystal plasticity algorithm in ABAQUS that was previously calibrated to study fatigue crack initiation in RR1000 Ni-base superalloy. Our work present simulations with non-zero applied mean strains and geometric discontinuities that were not previously considered for calibration. Results exhibit trends similar to those found in experiments for multiple metallic materials, conveying a consistent physical description of fatigue damage phenomena.« less

Monte Carlo simulation to investigate the formation of molecular hydrogen and its deuterated forms

NASA Astrophysics Data System (ADS)

Sahu, Dipen; Das, Ankan; Majumdar, Liton; Chakrabarti, Sandip K.

2015-07-01

H2 is the most abundant interstellar species, and its deuterated forms (HD and D2) are also present in high abundance. The high abundance of these molecules could be explained by considering the chemistry that occurs on interstellar dust. Because of its simplicity, the rate equation method is widely used to study the formation of grain-surface species. However, because the recombination efficiency for the formation of any surface species is highly dependent on various physical and chemical parameters, the Monte Carlo method is best suited for addressing the randomness of the processes. We perform Monte Carlo simulations to study the formation of H2, HD and D2 on interstellar ice. The adsorption energies of surface species are the key inputs for the formation of any species on interstellar dusts, but the binding energies of deuterated species have yet to be determined with certainty. A zero-point energy correction exists between hydrogenated and deuterated species, which should be considered during modeling of the chemistry on interstellar dusts. Following some previous studies, we consider various sets of adsorption energies to investigate the formation of these species under diverse physical conditions. As expected, notable differences in these two approaches (rate equation method and Monte Carlo method) are observed for the production of these simple molecules on interstellar ice. We introduce two factors, namely, Sf and β , to explain these discrepancies: Sf is a scaling factor, which can be used to correlate the discrepancies between the rate equation and Monte Carlo methods, and β indicates the formation efficiency under various conditions. Higher values of β indicate a lower production efficiency. We observed that β increases with a decrease in the rate of accretion from the gas phase to the grain phase.

Prevention of artificial dental plaque formation in vitro by plant extracts.

PubMed

Smullen, J; Finney, M; Storey, D M; Foster, H A

2012-10-01

A number of previous studies have shown that plant extracts can inhibit formation of dental plaque. The ability of extracts of Rosmarinus officianalis L., Salvia officianalis L., unfermented cocoa, red grape seed and green tea to inhibit plaque bacteria, glucosyltransferase activity, glucan and plaque formation in an in vitro model using bovine teeth was examined. The antimicrobial activity of the plant extracts against oral bacteria was determined using a standard susceptibility agar dilution technique. Inhibition of growth and acid production from glucose and sucrose by Streptococcus mutans in liquid culture was investigated. Prevention of plaque formation on bovine teeth initiated by Strep. mutans was studied using an artificial mouth. The plant extracts inhibited the growth of oral bacteria and prevented acid production by Strep. mutans. Extracts inhibited glucosyltransferase activity and glucan production and inhibited adhesion to glass. Extracts of R. officianalis L. and S. officianalis L. at 0·25 mg ml(-1) reduced plaque growth by >80%. Green tea extract completely inhibited plaque formation but resulted in a greenish discolouration of the teeth which could not be removed by scrubbing. The plant extracts, particularly those from R. officianalis L. and S. officianalis L., inhibited glucosyltranferase activity, glucan production and plaque formation in vitro. The results suggest that the extracts of R. officianalis L. and S. officianalis L. may be useful as antiplaque agents in foods and dental preparations. Bovine teeth can be used as an alternative to hydroxyapatite for studies of plaque formation, but they need to be carefully sterilized before use. © 2012 The Authors Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

MODELING CRYPTOSPORIDIUM PARVUM OOCYST INACTIVATION AND BROMATE IN A FLOW-THROUGH OZONE CONTACTOR TREATING NATURAL WATER

EPA Science Inventory

A reactive transport model was developed to simultaneously predict Cryptosporidium parvum oocyst inactivation and bromate formation during ozonation of natural water. A mechanistic model previously established to predict bromate formation in organic-free synthetic waters w...

Uranium isotope ratios of Muonionalusta troilite and complications for the absolute age of the IVA iron meteorite core

NASA Astrophysics Data System (ADS)

Brennecka, Gregory A.; Amelin, Yuri; Kleine, Thorsten

2018-05-01

The crystallization ages of planetary crustal material (given by basaltic meteorites) and planetary cores (given by iron meteorites) provide fiducial marks for the progress of planetary formation, and thus, the absolute ages of these objects fundamentally direct our knowledge and understanding of planet formation and evolution. The lone precise absolute age of planetary core material was previously obtained on troilite inclusions from the IVA iron meteorite Muonionalusta. This previously reported Pb-Pb age of 4565.3 ± 0.1 Ma-assuming a 238U/235U =137.88-only post-dated the start of the Solar System by approximately 2-3 million years, and mandated fast cooling of planetary core material. Since an accurate Pb-Pb age requires a known 238U/235U of the sample, we have measured both 238U/235U and Pb isotopic compositions of troilite inclusions from Muonionalusta. The measured 238U/235U of the samples range from ∼137.84 to as low as ∼137.22, however based on Pb and U systematics, terrestrial contamination appears pervasive and has affected samples to various extents for Pb and U. The cause of the relative 235U excess in one sample does not appear to be from terrestrial contamination or the decay of short-lived 247Cm, but is more likely from fractionation of U isotopes during metal-silicate separation during core formation, exacerbated by the extreme U depletion in the planetary core. Due to limited Pb isotopic variation and terrestrial disturbance, no samples of this study produced useful age information; however the clear divergence from the previously assumed 238U/235U of any troilite in Muonionalusta introduces substantial uncertainty to the previously reported absolute age of the sample without knowledge of the 238U/235U of the sample. Uncertainties associated with U isotope heterogeneity do not allow for definition of a robust age of solidification and cooling for the IVA core. However, one sample of this work-paired with previous work using short-lived radionuclides-suggests that the cooling age of the IVA core may be significantly younger than previously thought. This work indicates the metallic cores of protoplanetary bodies solidified no earlier than the first ∼5-10 million years of the Solar System.

The connection between globular cluster systems and their host galaxy and environment: a case study of the isolated elliptical NGC 821

NASA Astrophysics Data System (ADS)

Spitler, Lee R.; Forbes, Duncan A.; Strader, Jay; Brodie, Jean P.; Gallagher, Jay S.

2008-03-01

In an effort to probe the globular cluster (GC) system of an isolated elliptical galaxy, a comprehensive analysis of the NGC 821 GC system was performed. New imaging from the WIYN Mini-Mosaic imager, supplemented with Hubble Space Telescope (HST) WFPC2 images reveals a GC system similar to those found in counterpart ellipticals located in high-density environments. To put these results into the context of galaxy formation, a robustly determined census of GC systems is presented and analysed for galaxies spanning a wide range of masses (> M*), morphologies and environments. Results from this meta-study: (1) confirm previous findings that the number of GCs normalized by host galaxy stellar mass increases with host stellar mass. Spiral galaxies in the sample show smaller relative GC numbers than those of massive ellipticals, suggesting the GC systems of massive ellipticals were not formed from major spiral-spiral mergers; (2) indicate that GC system numbers per unit galaxy baryon mass increases with host baryon mass and that GC formation efficiency may not be universal as previously thought; (3) suggest previously reported trends with environment may be incorrect due to sample bias or the use of galaxy stellar masses to normalize GC numbers. Thus claims for environmentally dependent GC formation efficiencies should be revisited; (4) in combination with weak-lensing halo mass estimates, suggest that GCs formed in direct proportion to the halo mass; (5) are consistent with theoretical predictions whereby the local epoch of reionization did not vary significantly with environment or host galaxy type. Based upon data from the WIYN Observatory, which is a joint facility of the University of Wisconsin-Madison, Indiana University, Yale University and the National Optical Astronomy Observatories. Also includes analysis of observations made with the Hubble Space Telescope obtained from the ESO/ST-ECF Science Archive Facility. E-mail: lspitler@astro.swin.edu.au

Early treatment using fractional CO2 laser before skin suture during scar revision surgery in Asians.

PubMed

Du, Feiya; Yu, Yusheng; Zhou, Zhiqin; Wang, Liujia; Zheng, Shusen

2018-04-01

Fractional CO 2 laser is one of the most effective treatment options used to resurface scars. However, most previous studies have been performed on mature scars at least 2 months after surgery. Recent studies have emphasized the importance of early treatment to reduce scar formation. In the present study, we described our experience with fractional CO 2 laser intervention before skin suture during scar revision surgery in Asians, and found the treatment was safe and effective.

Chloramination of nitrogenous contaminants (pharmaceuticals and pesticides): NDMA and halogenated DBPs formation.

PubMed

Le Roux, Julien; Gallard, Hervé; Croué, Jean-Philippe

2011-05-01

Disinfection with chloramines is often used to reduce the production of regulated disinfection by-products (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). However, chloramination can lead to the formation of N-nitrosamines, including N-nitrosodimethylamine (NDMA), a probable human carcinogen. Previous research used dimethylamine (DMA) as a model precursor of NDMA, but certain widely used tertiary dimethylamines (e.g. the pharmaceutical ranitidine) show much higher conversion rates to NDMA than DMA. This study investigates the NDMA formation potential of several tertiary amines including pharmaceuticals and herbicides. The reactivity of these molecules with monochloramine (NH(2)Cl) is studied through the formation of NDMA, and other halogenated DBPs such as haloacetonitriles (HANs) and AOX (Adsorbable Organic Halides). Several compounds investigated formed NDMA in greater amounts than DMA, revealing the importance of structural characteristics of tertiary amines for NDMA formation. Among these compounds, the pharmaceutical ranitidine showed the highest molar conversion to NDMA. The pH and dissolved oxygen content of the solution were found to play a major role for the formation of NDMA from ranitidine. NDMA was formed in higher amounts at pH around pH 8 and a lower concentration of dissolved oxygen dramatically decreased NDMA yields. These findings seem to indicate that dichloramine (NHCl(2)) is not the major oxidant involved in the formation of NDMA from ranitidine, results in contradiction with the reaction mechanisms proposed in the literature. Dissolved oxygen was also found to influence the formation of other oxygen-containing DBPs (i.e. trichloronitromethane and haloketones). The results of this study identify several anthropogenic precursors of NDMA, indicating that chloramination of waters impacted by these tertiary amines could lead to the formation of significant amounts of NDMA and other non-regulated DBPs of potential health concern (e.g. dichloroacetonitrile or trichloronitromethane). This could be of particular importance for the chloramination of wastewater effluents, especially during water reuse processes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Students' trust judgements in online health information seeking.

PubMed

Rowley, Jennifer; Johnson, Frances; Sbaffi, Laura

2015-12-01

As one of the most active groups of Internet users, students and other young people are active users of digital health information. Yet, research into young people's evaluation of health information is limited, and no previous studies have focused on trust formation. In addition, prior studies on adults' use of digital information do not reach a consensus regarding the key factors in trust formation. This study seeks to address this gap. A questionnaire-based survey was used to collect data from undergraduate students studying a variety of disciplines in one UK university. The Trust in Online Health Information Scale is proposed, and it includes the following dimensions: authority, style, content, usefulness, brand, ease of use, recommendation, credibility, and verification. In addition, inspection of responses to specific items/questions provides further insights into aspects of the information that were of specific importance in influencing trust judgements. © The Author(s) 2014.

Microstructural Constraints on the Formation History of Hibonite in Refractory Inclusions

NASA Technical Reports Server (NTRS)

Han, J.; Koop, L.; Keller, L. P.; Davis, A. M.

2017-01-01

Hibonite is a primary refractory phase occurring in many Ca-Al-rich inclusions (CAIs), typically with spinel and perovskite [1]. Previous mi-crostructural studies of hibonite in CAIs revealed the presence of numerous stacking defects along the (001) plane and correlated non-stoichiometry in hibonite [2,3]. These features are interpreted as complex inter-growths of stoichiometric and Ca-deficient hibonites, as shown by experimental studies of reaction-sintered CaO-Al2O3 compounds [4]. Here, we extend our transmission electron microscope (TEM) studies to hibonite-bearing CAIs in CM chondrites that have been well characterized isotopically [5-7]. In addition, we have undertaken a series of anneal-ing experiments to explore the effect of minor elements (Mg and Ti) on the microstucure of hibonite [8,9,this study]. The results of these experiments are being applied to hibonite in CAIs in order to better understand its formation conditions.

Structural aspects of digestion of medium chain triglycerides studied in real time using sSAXS and Cryo-TEM.

PubMed

Phan, Stephanie; Hawley, Adrian; Mulet, Xavier; Waddington, Lynne; Prestidge, Clive A; Boyd, Ben J

2013-12-01

The purpose of this study was to investigate the colloidal structures formed on digestion of medium chain triglyceride (MCT) with a specific objective of identifying and characterizing a previously reported vesicular phase, which has been linked to supersaturation and anomalous digestion kinetics, and to evaluate the influence of lipid mass and enzyme inhibition on self assembled structure. MCT was digested in vitro and nanostructure was monitored in real time using synchrotron small angle X-ray scattering (sSAXS), and morphology was studied using cryogenic transmission electron microscopy (cryo-TEM). Formation of the putative vesicular phase formed on digestion of MCT was confirmed and its structural attributes were determined. Vesicle formation was dependent on lipid mass and bile salt concentration. The use of enzyme inhibitor for offline analysis of lipolysis samples did influence structural aspects of the digestion medium when compared to real time evaluation. The formation of a vesicular phase was directly linked to the kinetics of lipid digestion. Vesicle formation is linked to lipid mass, or more specifically the ratio of lipid to bile salts present in the digestion mixture. Inhibition of lipase to halt digestion during sampling for offline analysis must be done with caution as structural aspects were shown to differ for the MCT digests with and without inhibitor present.

Magnetic suppression of turbulence and the star formation activity of molecular clouds

NASA Astrophysics Data System (ADS)

Zamora-Avilés, Manuel; Vázquez-Semadeni, Enrique; Körtgen, Bastian; Banerjee, Robi; Hartmann, Lee

2018-03-01

We present magnetohydrodynamic simulations aimed at studying the effect of the magnetic suppression of turbulence (generated through various instabilities during the formation of molecular clouds by converging) on the subsequent star formation (SF) activity. We study four magnetically supercritical models with magnetic field strengths B = 0, 1, 2, and 3 μG (corresponding to mass-to-flux ratios of ∞, 4.76, 2.38, and 1.59 times the critical value), with the magnetic field, initially being aligned with the flows. We find that, for increasing magnetic field strength, the clouds formed tend to be more massive, denser, less turbulent, and with higher SF activity. This causes the onset of SF activity in the non-magnetic or more weakly magnetized cases to be delayed by a few Myr in comparison to the more strongly magnetized cases. We attribute this behaviour to the suppression of the non-linear thin shell instability (NTSI) by the magnetic field, previously found by Heitsch and coworkers. This result is contrary to the standard notion that the magnetic field provides support to the clouds, thus reducing their star formation rate. However, our result is a completely non-linear one, and could not be foreseen from simple linear considerations.

Effects of gaseous sulphuric acid on diesel exhaust nanoparticle formation and characteristics.

PubMed

Rönkkö, Topi; Lähde, Tero; Heikkilä, Juha; Pirjola, Liisa; Bauschke, Ulrike; Arnold, Frank; Schlager, Hans; Rothe, Dieter; Yli-Ojanperä, Jaakko; Keskinen, Jorma

2013-10-15

Diesel exhaust gaseous sulphuric acid (GSA) concentrations and particle size distributions, concentrations, and volatility were studied at four driving conditions with a heavy duty diesel engine equipped with oxidative exhaust after-treatment. Low sulfur fuel and lubricant oil were used in the study. The concentration of the exhaust GSA was observed to vary depending on the engine driving history and load. The GSA affected the volatile particle fraction at high engine loads; higher GSA mole fraction was followed by an increase in volatile nucleation particle concentration and size as well as increase of size of particles possessing nonvolatile core. The GSA did not affect the number of nonvolatile particles. At low and medium loads, the exhaust GSA concentration was low and any GSA driven changes in particle population were not observed. Results show that during the exhaust cooling and dilution processes, besides critical in volatile nucleation particle formation, GSA can change the characteristics of all nucleation mode particles. Results show the dual nature of the nucleation mode particles so that the nucleation mode can include simultaneously volatile and nonvolatile particles, and fulfill the previous results for the nucleation mode formation, especially related to the role of GSA in formation processes.

Spectroscopic and Kinetic Properties of the Molybdenum-containing, NAD+-dependent Formate Dehydrogenase from Ralstonia eutropha*

PubMed Central

Niks, Dimitri; Duvvuru, Jayant; Escalona, Miguel; Hille, Russ

2016-01-01

We have examined the rapid reaction kinetics and spectroscopic properties of the molybdenum-containing, NAD+-dependent FdsABG formate dehydrogenase from Ralstonia eutropha. We confirm previous steady-state studies of the enzyme and extend its characterization to a rapid kinetic study of the reductive half-reaction (the reaction of formate with oxidized enzyme). We have also characterized the electron paramagnetic resonance signal of the molybdenum center in its MoV state and demonstrated the direct transfer of the substrate Cα hydrogen to the molybdenum center in the course of the reaction. Varying temperature, microwave power, and level of enzyme reduction, we are able to clearly identify the electron paramagnetic resonance signals for four of the iron/sulfur clusters of the enzyme and find suggestive evidence for two others; we observe a magnetic interaction between the molybdenum center and one of the iron/sulfur centers, permitting assignment of this signal to a specific iron/sulfur cluster in the enzyme. In light of recent advances in our understanding of the structure of the molybdenum center, we propose a reaction mechanism involving direct hydride transfer from formate to a molybdenum-sulfur group of the molybdenum center. PMID:26553877

Probabilistic reasoning under time pressure: an assessment in Italian, Spanish and English psychology undergraduates

NASA Astrophysics Data System (ADS)

Agus, M.; Hitchcott, P. K.; Penna, M. P.; Peró-Cebollero, M.; Guàrdia-Olmos, J.

2016-11-01

Many studies have investigated the features of probabilistic reasoning developed in relation to different formats of problem presentation, showing that it is affected by various individual and contextual factors. Incomplete understanding of the identity and role of these factors may explain the inconsistent evidence concerning the effect of problem presentation format. Thus, superior performance has sometimes been observed for graphically, rather than verbally, presented problems. The present study was undertaken to address this issue. Psychology undergraduates without any statistical expertise (N = 173 in Italy; N = 118 in Spain; N = 55 in England) were administered statistical problems in two formats (verbal-numerical and graphical-pictorial) under a condition of time pressure. Students also completed additional measures indexing several potentially relevant individual dimensions (statistical ability, statistical anxiety, attitudes towards statistics and confidence). Interestingly, a facilitatory effect of graphical presentation was observed in the Italian and Spanish samples but not in the English one. Significantly, the individual dimensions predicting statistical performance also differed between the samples, highlighting a different role of confidence. Hence, these findings confirm previous observations concerning problem presentation format while simultaneously highlighting the importance of individual dimensions.

Diagnostic studies of ion beam formation in inductively coupled plasma

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

Jacobs, Jenee L.

2015-01-01

This dissertation describes a variety of studies focused on the plasma and the ion beam in inductively coupled plasma mass spectrometry (ICP-MS). The ability to use ICP-MS for measurements of trace elements in samples requires the analytes to be efficiently ionized. Updated ionization efficiency tables are discussed for ionization temperatures of 6500 K and 7000 K with an electron density of 1 x 10 15 cm -3. These values are reflective of the current operating parameters of ICP-MS instruments. Calculations are also discussed for doubly charged (M 2+) ion formation, neutral metal oxide (MO) ionization, and metal oxide (MO +)more » ion dissociation for similar plasma temperature values. Ionization efficiency results for neutral MO molecules in the ICP have not been reported previously.« less

The use of superparamagnetic nanoparticles for prosthetic biofilm prevention

PubMed Central

Taylor, Erik N; Webster, Thomas J

2009-01-01

As with all surgical procedures, implantation comes with the added risk of infection. The goal of this in vitro study was to explore the use of superparamagnetic iron oxide nanoparticles (SPION) as a multifunctional platform to prevent biofilm formation. Results showed for the first time decreased Staphylococcus epidermidis numbers when exposed to 100 μg/ml of SPION for 12 hours and this trend continued for up to 48 hours. Prevention of colony assembly, a prerequisite to biofilm formation, was also observed at lower SPION dosages of 10 μg/ml after 12 hours. Coupled with previous studies demonstrating enhanced bone cell functions in the presence of the same concentration of SPION, the present results provided much promise for the use of SPION for numerous anti-infection orthopedic applications. PMID:19774113

Disulphide bonds in casein micelle from milk.

PubMed

Bouguyon, Edwige; Beauvallet, Christian; Huet, Jean-Claude; Chanat, Eric

2006-05-05

Mammary epithelial cells synthesised and secreted caseins, the major milk proteins in most mammals, as large aggregates called micelles into the alveolar lumen they surround. We investigated the implication of the highly conserved cysteine(s) of kappa-casein in disulphide bond formation in casein micelles from several species. Dimers were found in all milks studied, confirming previous observation in ruminants. More importantly, the study of interchain disulphide bridges in mouse and rat casein micelles revealed that any casein possessing a cysteine is engaged in disulphide bond interchange; these species express four or five cysteine-containing caseins, respectively. We found that the main rodent caseins form both homo- and heterodimers. Additionally, disulphide bond formation among milk proteins was specific since the interaction of the caseins with cysteine-containing whey proteins was not observed in native casein micelles.

Femtosecond laser-induced periodic surface structures on silicon upon polarization controlled two-color double-pulse irradiation.

PubMed

Höhm, Sandra; Herzlieb, Marcel; Rosenfeld, Arkadi; Krüger, Jörg; Bonse, Jörn

2015-01-12

Two-color double-fs-pulse experiments were performed on silicon wafers to study the temporally distributed energy deposition in the formation of laser-induced periodic surface structures (LIPSS). A Mach-Zehnder interferometer generated parallel or cross-polarized double-pulse sequences at 400 and 800 nm wavelength, with inter-pulse delays up to a few picoseconds between the sub-ablation 50-fs-pulses. Multiple two-color double-pulse sequences were collinearly focused by a spherical mirror to the sample. The resulting LIPSS characteristics (periods, areas) were analyzed by scanning electron microscopy. A wavelength-dependent plasmonic mechanism is proposed to explain the delay-dependence of the LIPSS. These two-color experiments extend previous single-color studies and prove the importance of the ultrafast energy deposition for LIPSS formation.

Mechanism of Air Oxidation of the Fragrance Terpene Geraniol.

PubMed

Bäcktorp, Carina; Hagvall, Lina; Börje, Anna; Karlberg, Ann-Therese; Norrby, Per-Ola; Nyman, Gunnar

2008-01-01

The fragrance terpene geraniol autoxidizes upon air exposure and forms a mixture of oxidation products, some of which are skin sensitizers. Reactions of geraniol with O2 have been studied with DFT (B3LYP) and the computational results compared to experimentally observed product ratios. The oxidation is initiated by hydrogen abstraction, forming an allylic radical which combines with an O2 molecule to yield an intermediate peroxyl radical. In the subsequent step, geraniol differs from previously studied cases, in which the radical chain reaction is propagated through intermolecular hydrogen abstraction. The hydroxy-substituted allylic peroxyl radical prefers an intramolecular rearrangement, producing observable aldehydes and the hydroperoxyl radical, which in turn can propagate the radical reaction. Secondary oxidation products like epoxides and formates were also considered, and plausible reaction pathways for formation are proposed.

History and destiny of an emerging early-type galaxy. New IFU insights on the major-merger remnant NGC 7252

NASA Astrophysics Data System (ADS)

Weaver, J.; Husemann, B.; Kuntschner, H.; Martín-Navarro, I.; Bournaud, F.; Duc, P.-A.; Emsellem, E.; Krajnović, D.; Lyubenova, M.; McDermid, R. M.

2018-06-01

Context. The merging of galaxies is one key aspect in our favourite hierarchical ΛCDM Universe and is an important channel leading to massive quiescent elliptical galaxies. Understanding this complex transformational process is ongoing. Aims: We aim to study NGC 7252, which is one of the nearest major-merger galaxy remnants, observed 1 Gyr after the collision of presumably two gas-rich disc galaxies. It is therefore an ideal laboratory to study the processes inherent to the transformation of disc galaxies to ellipticals. Methods: We obtained wide-field IFU spectroscopy with the VLT-VIMOS integral-field spectrograph covering the central 50'' × 50'' of NGC 7252 to map the stellar and ionised gas kinematics, and the distribution and conditions of the ionised gas, revealing the extent of ongoing star formation and recent star formation history. Results: Contrary to previous studies, we find the inner gas disc not to be counter-rotating with respect to the stars. In addition, the stellar kinematics appear complex with a clear indication of a prolate-like rotation component which suggests a polar merger configuration. The ongoing star formation rate is 2.2 ± 0.6 M⊙ yr-1 and implies a typical depletion time of 2 Gyr given the molecular gas content. Furthermore, the spatially resolved star formation history suggests a slight radial dependence, moving outwards at later times. We confirm a large AGN-ionised gas cloud previously discovered 5 kpc south of the nucleus, and find a higher ionisation state of the ionised gas at the galaxy centre relative to the surrounding gas disc. Although the higher ionisation towards the centre is potentially degenerate within the central star forming ring, it may be associated with a low-luminosity AGN. Conclusions: Although NGC 7252 has been classified as post-starburst galaxy at the centre, the elliptical-like major-merger remnant still appears very active. A central kpc-scale gas disc has presumably re-formed quickly within the last 100 Myr after final coalescence. The disc features ongoing star formation, implying Gyr long timescale to reach the red sequence through gas consumption alone. While NGC 7252 is useful to probe the transformation from discs to ellipticals, it is not well-suited to study the transformation from blue to red at this point.

Rethinking the nature of fibrolamellar bone: an integrative biological revision of sauropod plexiform bone formation.

PubMed

Stein, Koen; Prondvai, Edina

2014-02-01

We present novel findings on sauropod bone histology that cast doubt on general palaeohistological concepts concerning the true nature of woven bone in primary cortical bone and its role in the rapid growth and giant body sizes of sauropod dinosaurs. By preparing and investigating longitudinal thin sections of sauropod long bones, of which transverse thin sections were published previously, we found that the amount of woven bone in the primary complex has been largely overestimated. Using comparative cellular and light-extinction characteristics in the two section planes, we revealed that the majority of the bony lamina consists of longitudinally organized primary bone, whereas woven bone is usually represented only by a layer a few cells thin in the laminae. Previous arguments on sauropod biology, which have been based on the overestimated amount, misinterpreted formation process and misjudged role of woven bone in the plexiform bone formation of sauropod dinosaurs, are thereby rejected. To explain the observed pattern in fossil bones, we review the most recent advances in bone biology concerning bone formation processes at the cellular and tissue levels. Differentiation between static and dynamic osteogenesis (SO and DO) and the revealed characteristics of SO- versus DO-derived bone tissues shed light on several questions raised by our palaeohistological results and permit identification of these bone tissues in fossils with high confidence. By presenting the methods generally used for investigating fossil bones, we show that the major cause of overestimation of the amount of woven bone in previous palaeohistological studies is the almost exclusive usage of transverse sections. In these sections, cells and crystallites of the longitudinally organized primary bone are cut transversely, thus cells appear rounded and crystallites remain dark under crossed plane polarizers, thereby giving the false impression of woven bone. In order to avoid further confusion in palaeohistological studies, we introduce new osteohistological terms as well as revise widely used but incorrect terminology. To infer the role of woven bone in the bone formation of fast-growing tetrapods, we review some aspects of the interrelationships between the vascularity of bone tissues, basal metabolic rate, body size and growth rate. By putting our findings into the context of osteogenesis, we provide a new model for the diametrical limb bone growth of sauropods and present new implications for the evolution of fast growth in vertebrates. Since biomechanical studies of bone tissues suggest that predominant collagen fibre orientation (CFO) is controlled by endogenous, functional and perhaps phylogenetic factors, the relationship between CFO and bone growth rate as defined by Amprino's rule, which has been the basis for the biological interpretation of several osteohistological features, must be revised. Our findings draw attention to the urgent need for revising widely accepted basic concepts of palaeohistological studies, and for a more integrative approach to bone formation, biomechanics and bone microstructural features of extant and extinct vertebrates to infer life history traits of long extinct, iconic animals like dinosaurs. © 2013 The Authors. Biological Reviews © 2013 Cambridge Philosophical Society.

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

Felicelli, S.D.; Poirier, D.R.; Heinrich, J.C.

The formation of macrosegregation defects known as freckles was simulated using a three-dimensional finite element model that calculates the thermosolutal convection and macrosegregation during the dendritic solidification of multicomponent alloys. A recently introduced algorithm was used to calculate the complicated solidification path of alloys of many components, which can accommodate liquidus temperatures that are general functions of liquid concentrations. The calculations are started from an all-liquid state, and the growth of the mushy zone is followed in time. Simulations are started from an all-liquid state, and the growth of the mushy zone is followed in time. Simulations of a Ni-Al-Ta-Wmore » alloy were performed on a rectangular cylinder until complete solidification. The results reveal details of the formation of freckles not previously observed in two-dimensional simulations. Liquid plumes in the form of chimney convection emanate from channels within the mushy zone, with similar qualitative features previously observed in transparent systems. Associated with the formation of channels, there is a complex three-dimensional flow produced by the interaction of the different solutal buoyancies of the alloy solutes. Regions of enhanced solid growth develop around the channel mouths, which are visualized as volcanoes on top of the mushy zone. The prediction of volcanoes differs from previous calculations with multicomponent alloys in two dimensions, in which the volcanoes were not nearly as apparent. These and other features of freckle formation phenomena are illustrated.« less

Stereotype Formation: Biased by Association

ERIC Educational Resources Information Center

Le Pelley, Mike E.; Reimers, Stian J.; Calvini, Guglielmo; Spears, Russell; Beesley, Tom; Murphy, Robin A.

2010-01-01

We propose that biases in attitude and stereotype formation might arise as a result of learned differences in the extent to which social groups have previously been predictive of behavioral or physical properties. Experiments 1 and 2 demonstrate that differences in the experienced predictiveness of groups with respect to evaluatively neutral…

Functional Analysis of the Accessory Protein TapA in Bacillus subtilis Amyloid Fiber Assembly

PubMed Central

Romero, Diego; Vlamakis, Hera; Losick, Richard

2014-01-01

Bacillus subtilis biofilm formation relies on the assembly of a fibrous scaffold formed by the protein TasA. TasA polymerizes into highly stable fibers with biochemical and morphological features of functional amyloids. Previously, we showed that assembly of TasA fibers requires the auxiliary protein TapA. In this study, we investigated the roles of TapA sequences from the C-terminal and N-terminal ends and TapA cysteine residues in its ability to promote the assembly of TasA amyloid-like fibers. We found that the cysteine residues are not essential for the formation of TasA fibers, as their replacement by alanine residues resulted in only minor defects in biofilm formation. Mutating sequences in the C-terminal half had no effect on biofilm formation. However, we identified a sequence of 8 amino acids in the N terminus that is key for TasA fiber formation. Strains expressing TapA lacking these 8 residues were completely defective in biofilm formation. In addition, this TapA mutant protein exhibited a dominant negative effect on TasA fiber formation. Even in the presence of wild-type TapA, the mutant protein inhibited fiber assembly in vitro and delayed biofilm formation in vivo. We propose that this 8-residue sequence is crucial for the formation of amyloid-like fibers on the cell surface, perhaps by mediating the interaction between TapA or TapA and TasA molecules. PMID:24488317

Functional analysis of the accessory protein TapA in Bacillus subtilis amyloid fiber assembly.

PubMed

Romero, Diego; Vlamakis, Hera; Losick, Richard; Kolter, Roberto

2014-04-01

Bacillus subtilis biofilm formation relies on the assembly of a fibrous scaffold formed by the protein TasA. TasA polymerizes into highly stable fibers with biochemical and morphological features of functional amyloids. Previously, we showed that assembly of TasA fibers requires the auxiliary protein TapA. In this study, we investigated the roles of TapA sequences from the C-terminal and N-terminal ends and TapA cysteine residues in its ability to promote the assembly of TasA amyloid-like fibers. We found that the cysteine residues are not essential for the formation of TasA fibers, as their replacement by alanine residues resulted in only minor defects in biofilm formation. Mutating sequences in the C-terminal half had no effect on biofilm formation. However, we identified a sequence of 8 amino acids in the N terminus that is key for TasA fiber formation. Strains expressing TapA lacking these 8 residues were completely defective in biofilm formation. In addition, this TapA mutant protein exhibited a dominant negative effect on TasA fiber formation. Even in the presence of wild-type TapA, the mutant protein inhibited fiber assembly in vitro and delayed biofilm formation in vivo. We propose that this 8-residue sequence is crucial for the formation of amyloid-like fibers on the cell surface, perhaps by mediating the interaction between TapA or TapA and TasA molecules.

Bone tissue formation in extraction sockets from sites with advanced periodontal disease: a histomorphometric study in humans.

PubMed

Ahn, Jae-Jin; Shin, Hong-In

2008-01-01

To investigate postextraction bone formation over time in both diseased and healthy sockets. Core specimens of healing tissues following tooth extraction were obtained at the time of implant placement in patients treated between October 2005 and December 2007. A disease group and a control group were classified according to socket examination at the time of extraction. The biopsy specimens were analyzed histomorphometrically to measure the dimensional changes among 3 tissue types: epithelial layer, connective tissue area, and new bone tissue area. Fifty-five specimens from sites of previously advanced periodontal disease from 45 patients were included in the disease group. Another 12 specimens of previously healthy extraction sockets were collected from 12 different patients as a control. The postextraction period of the disease group varied from 2 to 42 weeks. In the disease group, connective tissue occupied most of the socket during the first 4 weeks. New bone area progressively replaced the connective tissue area after the first 4 weeks. The area proportion of new bone tissue exceeded that of connective tissue by 14 weeks. After 20 weeks, most extraction sockets in the disease group demonstrated continuous new bone formation. The control group exhibited almost complete socket healing after 10 weeks, with no more new bone formation after 20 weeks. Osseous regeneration in the diseased sockets developed more slowly than in the disease-free sockets. After 16 weeks, new bone area exceeded 50% of the total newly regenerated tissue in the sockets with severe periodontal destruction. In the control group, after 8 weeks, new bone area exceeded 50% of the total tissue.

Deep Chandra observations of HCG 16. I. Active nuclei, star formation, and galactic winds

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

O'Sullivan, E.; Zezas, A.; Vrtilek, J. M.

2014-10-01

We present new, deep Chandra X-ray and Giant Metrewave Radio Telescope 610 MHz observations of the spiral-galaxy-rich compact group HCG 16, which we use to examine nuclear activity, star formation, and high-luminosity X-ray binary populations in the major galaxies. We confirm the presence of obscured active nuclei in NGC 833 and NGC 835, and identify a previously unrecognized nuclear source in NGC 838. All three nuclei are variable on timescales of months to years, and for NGC 833 and NGC 835 this is most likely caused by changes in accretion rate. The deep Chandra observations allow us to detect formore » the first time an Fe Kα emission line in the spectrum of the Seyfert 2 nucleus of NGC 835. We find that NGC 838 and NGC 839 are both starburst-dominated systems, with only weak nuclear activity, in agreement with previous optical studies. We estimate the star formation rates in the two galaxies from their X-ray and radio emission, and compare these results with estimates from the infrared and ultraviolet bands to confirm that star formation in both galaxies is probably declining after galaxy-wide starbursts were triggered ∼400-500 Myr ago. We examine the physical properties of their galactic superwinds, and find that both have temperatures of ∼0.8 keV. We also examine the X-ray and radio properties of NGC 848, the fifth largest galaxy in the group, and show that it is dominated by emission from its starburst.« less

Origins Space Telescope: 3D infrared surveys of star formation and black hole growth in galaxies over cosmic time

NASA Astrophysics Data System (ADS)

Pope, Alexandra; Armus, Lee; bradford, charles; Origins Space Telescope STDT

2018-01-01

In the coming decade, new telescope facilities and surveys aim to provide a 3D map of the unobscured Universe over cosmic time. However, much of galaxy formation and evolution occurs behind dust, and is only observable through infrared observations. Previous extragalactic infrared surveys were fundamentally limited to a 2D mapping of the most extreme populations of galaxies due to spatial resolution and sensitivity. The Origins Space Telescope (OST) is the mission concept for the Far-Infrared Surveyor, one of the four science and technology definition studies sponsored by NASA to provide input to the 2020 Astronomy and Astrophysics Decadal survey. OST is planned to be a large aperture, actively-cooled telescope covering a wide span of the mid- to far-infrared spectrum, which will achieve spectral line sensitivities up to 1000 times deeper than previous infrared facilities. With powerful instruments such as the Medium Resolution Survey Spectrometer (MRSS), capable of simultaneous imaging and spectroscopy, the extragalactic infrared sky can finally be surveyed in 3D. In addition to spectroscopic redshifts, the rich suite of lines in the infrared provides unique diagnostics of the ongoing star formation (both obscured and unobscured) and the central supermassive black hole growth. In this poster, we present a simulated extragalactic survey with OST/MRSS which will detect millions of galaxies down to well below the knee of the infrared luminosity function. We demonstrate how this survey can map the coeval star formation and black hole growth in galaxies over cosmic time.

Simultaneous hydrogenation and UV-photolysis experiments of NO in CO-rich interstellar ice analogues; linking HNCO, OCN-, NH2CHO, and NH2OH

NASA Astrophysics Data System (ADS)

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

2016-08-01

The laboratory work presented here simulates the chemistry on icy dust grains as typical for the `CO freeze-out stage' in dark molecular clouds. It differs from previous studies in that solid-state hydrogenation and vacuum UV photoprocessing are applied simultaneously to co-depositing molecules. In parallel, the reactions at play are described for fully characterized laboratory conditions. The focus is on the formation of molecules containing both carbon and nitrogen atoms, starting with NO in CO-, H2CO-, and CH3OH-rich ices at 13 K. The experiments yield three important conclusions. (1) Without UV processing hydroxylamine (NH2OH) is formed, as reported previously. (2) With UV processing (energetic) NH2 is formed through photodissociation of NH2OH. This radical is key in the formation of species with an N-C bond. (3) The formation of three N-C bearing species, HNCO, OCN-, and NH2CHO, is observed. The experiments put a clear chemical link between these species; OCN- is found to be a direct derivative of HNCO and the latter is shown to have the same precursor as formamide (NH2CHO). Moreover, the addition of VUV competing channels decreases the amount of NO molecules converted into NH2OH by at least one order of magnitude. Consequently, this decrease in NH2OH formation yield directly influences the amount of NO molecules that can be converted into HNCO, OCN-, and NH2CHO.

Heterotopic bone formation in the musculus latissimus dorsi of sheep using β-tricalcium phosphate scaffolds: evaluation of an extended prefabrication time on bone formation and matrix degeneration.

PubMed

Spalthoff, S; Jehn, P; Zimmerer, R; Möllmann, U; Gellrich, N-C; Kokemueller, H

2015-06-01

We previously generated viable heterotopic bone in living animals and found that 3 months of intrinsic vascularization improved bone formation and matrix degeneration. In this study, we varied the pre-vascularization time to determine its effects on the kinetics of bone formation and ceramic degradation. Two 25-mm-long cylindrical β-tricalcium phosphate scaffolds were filled intraoperatively with autogenous iliac crest bone marrow and implanted in the latissimus dorsi muscle in six sheep. To examine the effect of axial perfusion, one scaffold was surgically implanted with (group C) or without (group D) a central vascular bundle. All animals were sacrificed 6 months postoperatively and histomorphometric measurements were compared to previous results. All implanted scaffolds exhibited ectopic bone growth. However, bone growth was not significantly different between the 3-month (group A, 0.191±0.097 vs. group C, 0.237±0.075; P=0.345) and 6-month (group B, 0.303±0.105 vs. group D, 0.365±0.258; P=0.549) pre-vascularization durations, regardless of vessel supply; early differences between surgically and extrinsically vascularized constructs disappeared after 6 months. Here, we describe a reliable procedure for generating ectopic bone in vivo. A 3-month pre-vascularization duration appears sufficient and ceramic degradation proceeds in accordance with bone generation, supporting the hypothesis of cell-mediated resorption. Copyright © 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Parser Combinators: a Practical Application for Generating Parsers for NMR Data

PubMed Central

Fenwick, Matthew; Weatherby, Gerard; Ellis, Heidi JC; Gryk, Michael R.

2013-01-01

Nuclear Magnetic Resonance (NMR) spectroscopy is a technique for acquiring protein data at atomic resolution and determining the three-dimensional structure of large protein molecules. A typical structure determination process results in the deposition of a large data sets to the BMRB (Bio-Magnetic Resonance Data Bank). This data is stored and shared in a file format called NMR-Star. This format is syntactically and semantically complex making it challenging to parse. Nevertheless, parsing these files is crucial to applying the vast amounts of biological information stored in NMR-Star files, allowing researchers to harness the results of previous studies to direct and validate future work. One powerful approach for parsing files is to apply a Backus-Naur Form (BNF) grammar, which is a high-level model of a file format. Translation of the grammatical model to an executable parser may be automatically accomplished. This paper will show how we applied a model BNF grammar of the NMR-Star format to create a free, open-source parser, using a method that originated in the functional programming world known as “parser combinators”. This paper demonstrates the effectiveness of a principled approach to file specification and parsing. This paper also builds upon our previous work [1], in that 1) it applies concepts from Functional Programming (which is relevant even though the implementation language, Java, is more mainstream than Functional Programming), and 2) all work and accomplishments from this project will be made available under standard open source licenses to provide the community with the opportunity to learn from our techniques and methods. PMID:24352525

2007 Combat Vehicles Conference - Today’s Challenges: Fighting, Sustaining, Modernizing and Transforming

DTIC Science & Technology

2007-10-24

Programs) 1 . FCS MULE .wmv format 2. FCS NLOS Crate Of Fire .wmv format 3. FCS Robotic Convoy .wmv format 4. FCS...included in these sessions will be two “back by popular demand” highlights from previous conferences: 1 ) an update on combat operations in iraq from...15 am - 11:30 am general session general sessiOn - sessiOn 1 : “today’s challenges: fighting, sustaining, modernizing and transforming

Studies of the Escherichia coli Rsd-sigma70 complex.

PubMed

Westblade, Lars F; Ilag, Leopold L; Powell, Andrew K; Kolb, Annie; Robinson, Carol V; Busby, Stephen J W

2004-01-16

Escherichia coli Rsd protein was previously identified on the basis of its binding to the RNA polymerase sigma(70) subunit. The Rsd-sigma(70) complex has been studied using different methods. Our data show that Rsd associates with sigma(70) to form a complex with a stoichiometry of 1:1. Alanine scanning and deletion mutagenesis were used to locate regions of sigma(70) that are required for the formation of the Rsd-sigma(70) complex.

Optimized Model Surfaces for Advanced Atomic Force Microscopy Studies of Surface Nanobubbles.

PubMed

Song, Bo; Zhou, Yi; Schönherr, Holger

2016-11-01

The formation of self-assembled monolayers (SAMs) of binary mixtures of 16-mercaptohexadecanoic acid (MHDA) and 1-octadecanethiol (ODT) on ultraflat template-stripped gold (TSG) surfaces was systematically investigated to clarify the assembly behavior, composition, and degree of possible phase segregation in light of atomic force microscopy (AFM) studies of surface nanobubbles on these substrates. The data for SAMs on TSG were compared to those obtained by adsorption on rough evaporated gold, as reported in a previous study. Quartz crystal microbalance and surface plasmon resonance data acquired in situ on TSG indicate that similar to SAM formation on conventional evaporated gold substrates ODT and MHDA form monolayers and bilayers, respectively. The second layer on MHDA, whose formation is attributed to hydrogen bonding, can be easily removed by adequate rinsing with water. The favorable agreement of the grazing incidence reflection Fourier transform infrared (GIR FTIR) spectroscopy and contact angle data analyzed with the Israelachvili-Gee model suggests that the binary SAMs do not segregate laterally. This conclusion is fully validated by high-resolution friction force AFM observations down to a length scale of 8-10 nm, which is much smaller than the typical observed surface nanobubble radii. Finally, correspondingly functionalized TSG substrates are shown to be valuable supports for studying surface nanobubbles by AFM in water and for addressing the relation between surface functionality and nanobubble formation and properties.

Hematological measurements in rats flown on Spacelab shuttle, SL-3

NASA Technical Reports Server (NTRS)

Lange, R. D.; Andrews, R. B.; Gibson, L. A.; Congdon, C. C.; Wright, P.; Dunn, C. D.; Jones, J. B.

1987-01-01

Previous studies have shown that a decrease in red cell mass occurs in astronauts, and some studies indicate a leukocytosis occurs. A life science module housing young and mature rats was flown on shuttle mission Spacelab 3 (SL-3), and the results of hematology studies of flight and control rats are presented. Statistically significant increases in the hematocrit, red blood cell counts, and hemoglobin determinations, together with a mild neutrophilia and lymphopenia, were found in flight animals. No significant changes were found in bone marrow and spleen cell differentials or erythropoietin determinations. Clonal assays demonstrated an increased erythroid colony formation of flight animal bone marrow cells at erythropoietin doses of 0.02 and 1.0 U/ml but not 0.20 U/ml. These results agree with some but vary from other previously published studies. Erythropoietin assays and clonal studies were performed for the first time.

Dependence of future mortality changes on global CO2 concentrations: A review.

PubMed

Lee, Jae Young; Choi, Hayoung; Kim, Ho

2018-05-01

The heterogeneity among previous studies of future mortality projections due to climate change has often hindered comparisons and syntheses of resulting impacts. To address this challenge, the present study introduced a novel method to normalize the results from projection studies according to different baseline and projection periods and climate scenarios, thereby facilitating comparison and synthesis. This study reviewed the 15 previous studies involving projected climate change-related mortality under Representative Concentration Pathways. To synthesize their results, we first reviewed the important study design elements that affected the reported results in previous studies. Then, we normalized the reported results by CO 2 concentration in order to eliminate the effects of the baseline period, projection period, and climate scenario choices. For twenty-five locations worldwide, the normalized percentage changes in temperature-attributable mortality per 100 ppm increase in global CO 2 concentrations ranged between 41.9% and 330%, whereas those of total mortality ranged between 0.3% and 4.8%. The normalization methods presented in this work will guide future studies to provide their results in a normalized format and facilitate research synthesis to reinforce our understanding on the risk of climate change. Copyright © 2018 Elsevier Ltd. All rights reserved.

Morusinol extracted from Morus alba inhibits arterial thrombosis and modulates platelet activation for the treatment of cardiovascular disease.

PubMed

Lee, Jung-Jin; Yang, Hyun; Yoo, Yeong-Min; Hong, Seong Su; Lee, Dongho; Lee, Hyun-Jung; Lee, Hak-Ju; Myung, Chang-Seon; Choi, Kyung-Chul; Jeung, Eui-Bae

2012-01-01

Morus alba (white mulberry) has been used in traditional Chinese medicine as an anti-headache, diuretic, expectorant, and anti-diabetic agent. In previous studies, extracts of Morus alba demonstrated favorable biological properties, such as antioxidant activity, suppression of lipoxygenase (LOX)-1, cytotoxicity against cancer cells, and inhibition of the invasion and migration of cancer cells. This study further evaluated the effects of morusinol, a flavonoid derived from Morus alba root bark, on platelet aggregation and thromboxane B(2) (TXB(2) formation in vitro and thrombus formation in vivo. The antiplatelet potential of morusinol was measured using in vitro rabbit platelet aggregation and TXB(2) formation assays. Arterial thrombus formation was investigated using an in vivo ferric chloride (FeCl(3)-induced thrombosis model. Morusinol significantly inhibited collagen- and arachidonic acid-induced platelet aggregation and TXB(2) formation in cultured platelets in a concentration-dependent manner. Thrombus formation was reduced by 32.1, 42.0, and 99.0% for collagen-induced TXB(2) formation, and 8.0, 24.1, and 29.2% for arachadonic acid-induced TXB(2) formation, with 5, 10, and 30 µg/mL morusinol, respectively. Moreover, oral morusinol (20 mg/kg) or aspirin (20 mg/kg) for three days significantly increased the time to occlusion in vivo by 20.3±5.0 or 6.8±2.9 min, respectively, compared with the control (1% CMC, carboxymethyl cellulose). Taken together, these results indicate that morusinol may significantly inhibit arterial thrombosis in vivo due to antiplatelet activity. Thus, morusinol may exert beneficial effects on transient ischemic attacks or stroke via the modulation of platelet activation.

RhoA regulates Activin B-induced stress fiber formation and migration of bone marrow-derived mesenchymal stromal cell through distinct signaling.

PubMed

Wang, Xueer; Tang, Pei; Guo, Fukun; Zhang, Min; Chen, Yinghua; Yan, Yuan; Tian, Zhihui; Xu, Pengcheng; Zhang, Lei; Zhang, Lu; Zhang, Lin

2017-01-01

In our previous study, Activin B induced actin stress fiber formation and cell migration in Bone marrow-derived mesenchymal stem cells (BMSCs) in vitro. However, the underlying molecular mechanisms are not well studied. RhoA is recognized to play a critical role in the regulation of actomyosin cytoskeletal organization and cell migration. Pull-down assay was performed to investigate the activity of RhoA. The dominant-negative mutants of RhoA (RhoA(N19)) was used to determine whether RhoA has a role in Activin B-induced cytoskeleton organization and cell migration in BMSCs. Cytoskeleton organization was examined by fluorescence Rhodamine-phalloidin staining, and cell migration by transwell and cell scratching assay. Western blot was carried out to investigate downstream signaling cascade of RhoA. Inhibitor and siRNAs were used to detect the role of downstream signaling in stress fiber formation and/or cell migration. RhoA was activated by Activin B in BMSCs. RhoA(N19) blocked Activin B-induced stress fiber formation and cell migration. ROCK inhibitor blocked Activin B-induced stress fiber formation but enhanced BMSCs migration. Activin B induced phosphorylation of LIMK2 and Cofilin, which was abolished by ROCK inhibition. Both of siRNA LIMK2 and siRNA Cofilin inhibited Activin B-induced stress fiber formation. RhoA regulates Activin B-induced stress fiber formation and migration of BMSCs. A RhoA-ROCK-LIMK2-Cofilin signaling node exists and regulates actin stress fiber formation. RhoA regulates Activin B-induced cell migration independent of ROCK. Better understanding of the molecular mechanisms of BMSCs migration will help optimize therapeutic strategy to target BMSCs at injured tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of peg formation in cucumber seedlings grown on clinostats and in a microgravity (space) environment.

PubMed

Link, B M; Cosgrove, D J

1999-12-01

In young cucumber seedlings, the peg is a polar out-growth of tissue that functions by snagging the seed coat, thereby freeing the cotyledons. Previous studies have indicated that peg formation is gravity dependent. In this study we analyzed peg formation in cucumber seedlings (Cucumis sativus L. cv Burpee Hybrid II) grown under conditions of normal gravity, microgravity, and simulated microgravity (clinostat rotation). Seeds were germinated on the ground, in clinostats and on board the space shuttle (STS 95) for 1-2 days, frozen and subsequently examined for their stage of development, degree of hook formation, number of pegs formed, and peg morphology. The frequency of peg formation in space grown seedlings was found to be nearly identical to that of clinostat grown seedlings and to differ from that of seedlings germinated under normal gravity only in a minority of cases; approximately 6% of the seedlings formed two pegs and nearly 2% of the seedlings lacked pegs, whereas such abnormalities did not occur in ground controls. The degree of hook formation was found to be less pronounced for space grown seedlings, compared to clinostat grown seedlings, indicating a greater degree of decoupling between peg formation and hook formation in space. Nonetheless, in all seedlings having single pegs and a hook, the peg was found to be positioned correctly on the inside of the hook, showing that there is coordinate development even in microgravity environments. Peg morphologies were altered in space grown samples, with the pegs having a blunt appearance and many pegs showing alterations in expansion, with the peg extending out over the edges of the seed coat and downwards. These phenotypes were not observed in clinostat or ground grown seedlings.

Analysis of peg formation in cucumber seedlings grown on clinostats and in a microgravity (space) environment

NASA Technical Reports Server (NTRS)

Link, B. M.; Cosgrove, D. J.

1999-01-01

In young cucumber seedlings, the peg is a polar out-growth of tissue that functions by snagging the seed coat, thereby freeing the cotyledons. Previous studies have indicated that peg formation is gravity dependent. In this study we analyzed peg formation in cucumber seedlings (Cucumis sativus L. cv Burpee Hybrid II) grown under conditions of normal gravity, microgravity, and simulated microgravity (clinostat rotation). Seeds were germinated on the ground, in clinostats and on board the space shuttle (STS 95) for 1-2 days, frozen and subsequently examined for their stage of development, degree of hook formation, number of pegs formed, and peg morphology. The frequency of peg formation in space grown seedlings was found to be nearly identical to that of clinostat grown seedlings and to differ from that of seedlings germinated under normal gravity only in a minority of cases; approximately 6% of the seedlings formed two pegs and nearly 2% of the seedlings lacked pegs, whereas such abnormalities did not occur in ground controls. The degree of hook formation was found to be less pronounced for space grown seedlings, compared to clinostat grown seedlings, indicating a greater degree of decoupling between peg formation and hook formation in space. Nonetheless, in all seedlings having single pegs and a hook, the peg was found to be positioned correctly on the inside of the hook, showing that there is coordinate development even in microgravity environments. Peg morphologies were altered in space grown samples, with the pegs having a blunt appearance and many pegs showing alterations in expansion, with the peg extending out over the edges of the seed coat and downwards. These phenotypes were not observed in clinostat or ground grown seedlings.

Enzyme-Mediated Conversion of Flavin Adenine Dinucleotide (FAD) to 8-Formyl FAD in Formate Oxidase Results in a Modified Cofactor with Enhanced Catalytic Properties.

PubMed

Robbins, John M; Souffrant, Michael G; Hamelberg, Donald; Gadda, Giovanni; Bommarius, Andreas S

2017-07-25

Flavins, including flavin adenine dinucleotide (FAD), are fundamental catalytic cofactors that are responsible for the redox functionality of a diverse set of proteins. Alternatively, modified flavin analogues are rarely found in nature as their incorporation typically results in inactivation of flavoproteins, thus leading to the disruption of important cellular pathways. Here, we report that the fungal flavoenzyme formate oxidase (FOX) catalyzes the slow conversion of noncovalently bound FAD to 8-formyl FAD and that this conversion results in a nearly 10-fold increase in formate oxidase activity. Although the presence of an enzyme-bound 8-formyl FMN has been reported previously as a result of site-directed mutagenesis studies of lactate oxidase, FOX is the first reported case of 8-formyl FAD in a wild-type enzyme. Therefore, the formation of the 8-formyl FAD cofactor in formate oxidase was investigated using steady-state kinetics, site-directed mutagenesis, ultraviolet-visible, circular dichroism, and fluorescence spectroscopy, liquid chromatography with mass spectrometry, and computational analysis. Surprisingly, the results from these studies indicate not only that 8-formyl FAD forms spontaneously and results in the active form of FOX but also that its autocatalytic formation is dependent on a nearby arginine residue, R87. Thus, this work describes a new enzyme cofactor and provides insight into the little-understood mechanism of enzyme-mediated 8α-flavin modifications.

(Z)-5-(2,4-Dihydroxybenzylidene)thiazolidine-2,4-dione Prevents UVB-Induced Melanogenesis and Wrinkle Formation through Suppressing Oxidative Stress in HRM-2 Hairless Mice

PubMed Central

Lee, Bonggi; Moon, Kyoung Mi; Kim, Seong Jin; Kim, So Hee; Kim, Dae Hyun; An, Hye Jin; Jeong, Ji Won; Kim, Ye Ra; Son, Sujin; Kim, Min Jo; Chung, Ki Wung; Lee, Eun Kyeong; Chun, Pusoon; Ha, Young Mi; Kim, Min-Sun; Mo, Sang Hyun; Moon, Hyung Ryong; Chung, Hae Young

2016-01-01

Background. Uncontrolled melanogenesis and wrinkle formation are an indication of photoaging. Our previous studies demonstrated that (Z)-5-(2,4-dihydroxybenzylidene)thiazolidine-2,4-dione (MHY498) inhibited tyrosinase activity and melanogenesis in vitro. Objective. To examine in vivo effects of MHY498 as an antiaging compound on UVB-induced melanogenesis and wrinkle formation, we topically applied MHY498 on dorsal skin of HRM-2 hairless mice. Methods. Using histological analysis, we evaluated effects of MHY498 on melanogenesis and wrinkle formation after UVB exposure. In addition, related molecular signaling pathways were examined using western blotting, fluorometric assay, and enzyme-linked immunosorbent assay. Results. MHY498 suppressed UVB-induced melanogenesis by inhibiting phosphorylation of CREB and translocation of MITF protein into the nucleus, which are key factors for tyrosinase expression. Consistently, tyrosinase protein levels were notably reduced in the dorsal skin of the hairless mice by MHY498 treatment. Furthermore, MHY498 inhibited UVB-induced wrinkle formation and collagen fiber destruction by increasing type 1 procollagen concentration and decreasing protein expression levels of MMPs, which play an essential role in collagen fiber degradation. As a mechanism, MHY498 notably ameliorated UVB-induced oxidative stress and NF-κB activation in the dermal skin of the hairless mice. Conclusion. Our study suggests that MHY498 can be used as a therapeutic or cosmetic agent for preventing uncontrolled melanogenesis and wrinkle formation. PMID:27242917

Accurate and computationally efficient prediction of thermochemical properties of biomolecules using the generalized connectivity-based hierarchy.

PubMed

Sengupta, Arkajyoti; Ramabhadran, Raghunath O; Raghavachari, Krishnan

2014-08-14

In this study we have used the connectivity-based hierarchy (CBH) method to derive accurate heats of formation of a range of biomolecules, 18 amino acids and 10 barbituric acid/uracil derivatives. The hierarchy is based on the connectivity of the different atoms in a large molecule. It results in error-cancellation reaction schemes that are automated, general, and can be readily used for a broad range of organic molecules and biomolecules. Herein, we first locate stable conformational and tautomeric forms of these biomolecules using an accurate level of theory (viz. CCSD(T)/6-311++G(3df,2p)). Subsequently, the heats of formation of the amino acids are evaluated using the CBH-1 and CBH-2 schemes and routinely employed density functionals or wave function-based methods. The calculated heats of formation obtained herein using modest levels of theory and are in very good agreement with those obtained using more expensive W1-F12 and W2-F12 methods on amino acids and G3 results on barbituric acid derivatives. Overall, the present study (a) highlights the small effect of including multiple conformers in determining the heats of formation of biomolecules and (b) in concurrence with previous CBH studies, proves that use of the more effective error-cancelling isoatomic scheme (CBH-2) results in more accurate heats of formation with modestly sized basis sets along with common density functionals or wave function-based methods.

Formation of Hydrogen Sulfide in Wine: Interactions between Copper and Sulfur Dioxide.

PubMed

Bekker, Marlize Z; Smith, Mark E; Smith, Paul A; Wilkes, Eric N

2016-09-10

The combined synergistic effects of copper (Cu(2+)) and sulfur dioxide (SO₂) on the formation of hydrogen sulfide (H₂S) in Verdelho and Shiraz wine samples post-bottling was studied over a 12-month period. The combined treatment of Cu(2+) and SO₂ significantly increased H₂S formation in Verdelho wines samples that were not previously treated with either Cu(2+) or SO₂. The formation of H₂S produced through Cu(2+) mediated reactions was likely either: (a) directly through the interaction of SO₂ with either Cu(2+) or H₂S; or (b) indirectly through the interaction of SO₂ with other wine matrix compounds. To gain better understanding of the mechanisms responsible for the significant increases in H₂S concentration in the Verdelho samples, the interaction between Cu(2+) and SO₂ was studied in a model wine matrix with and without the presence of a representative thiol quenching compound (4-methylbenzoquinone, 4MBQ). In these model studies, the importance of naturally occurring wine compounds and wine additives, such as quinones, SO₂, and metal ions, in modulating the formation of H₂S post-bottling was demonstrated. When present in equimolar concentrations a 1:1 ratio of H₂S- and SO₂-catechol adducts were produced. At wine relevant concentrations, however, only SO₂-adducts were produced, reinforcing that the competition reactions of sulfur nucleophiles, such as H₂S and SO₂, with wine matrix compounds play a critical role in modulating final H₂S concentrations in wines.

The adaptor protein p62 is involved in RANKL-induced autophagy and osteoclastogenesis.

PubMed

Li, Rui-Fang; Chen, Gang; Ren, Jian-Gang; Zhang, Wei; Wu, Zhong-Xing; Liu, Bing; Zhao, Yi; Zhao, Yi-Fang

2014-12-01

Previous studies have implicated autophagy in osteoclast differentiation. The aim of this study was to investigate the potential role of p62, a characterized adaptor protein for autophagy, in RANKL-induced osteoclastogenesis. Real-time quantitative PCR and western blot analyses were used to evaluate the expression levels of autophagy-related markers during RANKL-induced osteoclastogenesis in mouse macrophage-like RAW264.7 cells. Meanwhile, the potential relationship between p62/LC3 localization and F-actin ring formation was tested using double-labeling immunofluorescence. Then, the expression of p62 in RAW264.7 cells was knocked down using small-interfering RNA (siRNA), followed by detecting its influence on RANKL-induced autophagy activation, osteoclast differentiation, and F-actin ring formation. The data showed that several key autophagy-related markers including p62 were significantly altered during RANKL-induced osteoclast differentiation. In addition, the expression and localization of p62 showed negative correlation with LC3 accumulation and F-actin ring formation, as demonstrated by western blot and immunofluorescence analyses, respectively. Importantly, the knockdown of p62 obviously attenuated RANKL-induced expression of autophagy- and osteoclastogenesis-related genes, formation of TRAP-positive multinuclear cells, accumulation of LC3, as well as formation of F-actin ring. Our study indicates that p62 may play essential roles in RANKL-induced autophagy and osteoclastogenesis, which may help to develop a novel therapeutic strategy against osteoclastogenesis-related diseases. © The Author(s) 2014.

Judgment and judgment latency for freedom and responsibility relatedness as a function of subtle linguistic variations.

PubMed

Wilkerson, Keith; McGahan, Joseph R; Stevens, Rick; Williamson, David; Low, Jean

2009-12-01

The goal of this study was to determine whether differential response formats to covariation problems influence corresponding response latencies. The authors provided participants with 3 trials of 16 statements addressing positive and negative relations between freedom and responsibility. The authors framed half of the items around responsibility given freedom and the other half around freedom given responsibility. Response formats comprised true-false, agree-disagree, and yes-no answers as a between-participants factor. Results indicated that the manipulation of response format did not affect latencies. However, latencies differed according to the framing of the items. For items framed around freedom given responsibility, latencies were shorter. In addition, participants were more likely to report a positive relation between freedom and responsibility when items were framed around freedom given responsibility. The authors discuss implications relative to previous research in this area and give recommendations for future research.

Melt-growth dynamics in CdTe crystals

DOE PAGES

Zhou, X. W.; Ward, D. K.; Wong, B. M.; ...

2012-06-01

We use a new, quantum-mechanics-based bond-order potential (BOP) to reveal melt growth dynamics and fine scale defect formation mechanisms in CdTe crystals. Previous molecular dynamics simulations of semiconductors have shown qualitatively incorrect behavior due to the lack of an interatomic potential capable of predicting both crystalline growth and property trends of many transitional structures encountered during the melt → crystal transformation. Here, we demonstrate successful molecular dynamics simulations of melt growth in CdTe using a BOP that significantly improves over other potentials on property trends of different phases. Our simulations result in a detailed understanding of defect formation during themore » melt growth process. Equally important, we show that the new BOP enables defect formation mechanisms to be studied at a scale level comparable to empirical molecular dynamics simulation methods with a fidelity level approaching quantum-mechanical methods.« less

Proterotheriidae (Mammalia, Litopterna) from the Cerro Azul Formation (late Miocene), La Pampa Province, Argentina

NASA Astrophysics Data System (ADS)

Schmidt, G. I.; Montalvo, C. I.; Sostillo, R.; Cerdeño, E.

2018-04-01

Remains of Proterotheriidae (Litopterna) recovered from different localities in La Pampa Province, Argentina, are described. The fossiliferous levels in these localities correspond to the Cerro Azul Formation (late Miocene), where Chasicoan and Huayquerian faunal associations are known. The specimens of Proterotheriidae herein studied are assigned to Diplasiotherium pampa, Eoauchenia primitiva, cf. Brachytherium cuspidatum, Neobrachytherium sp. and Proterotheriidae indet. Although the holotype of D. pampa (left mandibular fragment with p3-m2) was defined in a previous paper, it is figured and fully described here, and its m3 is now known among the new collected specimens. Eoauchenia, Brachytherium and Neobrachytherium are registered in La Pampa Province for the first time, and the record of E. primitiva extends back to late Miocene its temporal distribution. Proterotheriids from the Cerro Azul Formation gather exclusive elements and others related to taxa represented in different Argentinean geological units corresponding to late Miocene-early Pliocene period.

Myomaker is a membrane activator of myoblast fusion and muscle formation.

PubMed

Millay, Douglas P; O'Rourke, Jason R; Sutherland, Lillian B; Bezprozvannaya, Svetlana; Shelton, John M; Bassel-Duby, Rhonda; Olson, Eric N

2013-07-18

Fusion of myoblasts is essential for the formation of multi-nucleated muscle fibres. However, the identity of muscle-specific proteins that directly govern this fusion process in mammals has remained elusive. Here we identify a muscle-specific membrane protein, named myomaker, that controls myoblast fusion. Myomaker is expressed on the cell surface of myoblasts during fusion and is downregulated thereafter. Overexpression of myomaker in myoblasts markedly enhances fusion, and genetic disruption of myomaker in mice causes perinatal death due to an absence of multi-nucleated muscle fibres. Remarkably, forced expression of myomaker in fibroblasts promotes fusion with myoblasts, demonstrating the direct participation of this protein in the fusion process. Pharmacological perturbation of the actin cytoskeleton abolishes the activity of myomaker, consistent with previous studies implicating actin dynamics in myoblast fusion. These findings reveal a long-sought myogenic fusion protein that controls mammalian myoblast fusion and provide new insights into the molecular underpinnings of muscle formation.

Heart rate variability reactivity and new romance: Cause or consequence?

PubMed

Bailey, Laura K; Davis, Ron

2017-09-01

There are documented physiological differences between single and coupled individuals during the "honeymoon period" of nascent romantic relationships. One such difference is in autonomic reactivity, specifically heart rate variability (HRV) reactivity. This finding had previously been interpreted as evidence of a stress buffering effect of relationship formation. The present study explored among university women two competing longitudinal hypotheses conceptualizing differences in HRV reactivity as either a cause or a consequence of romantic relationship formation. Results did not support the hypothesis that HRV reactivity changes as a consequence of beginning a new romantic relationship. Instead, lower HRV reactivity predicted greater relationship formation amongst women with low BMI and higher resting HRV. The functioning of the heart therefore predicted the likelihood that an individual would find love. These interactions may be the result of differing success rates of various mating strategies for women with low and high BMI and HRV. Copyright © 2017 Elsevier B.V. All rights reserved.

Expression of pathogenicity-related genes of Xylella fastidiosa in vitro and in planta.

PubMed

de Souza, Alessandra A; Takita, Marco A; Pereira, Eridan O; Coletta-Filho, Helvécio D; Machado, Marcos A

2005-04-01

Xylella fastidiosa is responsible for several economically important plant diseases. It is currently assumed that the symptoms are caused by vascular occlusion due to biofilm formation. Microarray technology was previously used to examine the global gene expression profile of X. fastidiosa freshly isolated from symptomatic plants or after several passages by axenic culture medium, and different pathogenicity profiles have been obtained. In the present study the expression of some pathogenicity-related genes was evaluated in vitro and in planta by RT-PCR. The results suggest that adhesion is important at the beginning of biofilm formation, while the genes related to adaptation are essential for the organism's maintenance in planta. Similar results were observed in vitro mainly for the adhesion genes. The pattern of expression observed suggests that adhesion modulates biofilm formation whereas the expression of some adaptation genes may be related to the environment in which the organism is living.

Determination of complex formation constants by phase sensitive alternating current polarography: Cadmium-polymethacrylic acid and cadmium-polygalacturonic acid.

PubMed

Garrigosa, Anna Maria; Gusmão, Rui; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

2007-10-15

The use of phase sensitive alternating current polarography (ACP) for the evaluation of complex formation constants of systems where electrodic adsorption is present has been proposed. The applicability of the technique implies the previous selection of the phase angle where contribution of capacitive current is minimized. This is made using Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) in the analysis of ACP measurements at different phase angles. The method is checked by the study of the complexation of Cd by polymethacrylic (PMA) and polygalacturonic (PGA) acids, and the optimal phase angles have been ca. -10 degrees for Cd-PMA and ca. -15 degrees for Cd-PGA systems. The goodness of phase sensitive ACP has been demonstrated comparing the determined complex formation constants with those obtained by reverse pulse polarography, a technique that minimizes the electrode adsorption effects on the measured currents.

Lower Miocene stratigraphy of the Gebel Shabrawet area, north Eastern desert Egypt

NASA Astrophysics Data System (ADS)

Abdelghany, Osman

2002-05-01

The Lower Miocene carbonate/siliciclastic sequence of the Shabrawet area, comprises a complex alternation of autochthonous and allogenic sediments. The sequence can be subdivided into two lithostratigraphic units. The lower unit (unit I) is equivalent to the Gharra Formation. It is mainly clastic and composed of sandstones, siltstones and shales with minor limestone intercalations. These sediments are rich in Clypeaster spp., Scutella spp., Miogypsina intermedia, Operculina complanata, and smaller foraminifera. The upper unit (unit II) was considered by previous workers as being equivalent to the Marmarica Formation. It consists mainly of non-clastic rocks, dominated by sandy and chalky limestones rich in larger foraminifera (miogypsinids and nummulitids). This unit is topped by a highly fossiliferous ( Heterostegina, Operculina and Planostegina) sandy limestone. The present study places both units in the Gharra Formation and reports for the first time M. intermedia from the Miocene sequence of the Shabrawet area.

High resolution 40AR/39AR chronostratigraphy of the Late Cretaceous El Gallo Formation, Baja California del Norte, Mexico

NASA Astrophysics Data System (ADS)

Renne, Paul R.; Fulford, Madeleine M.; Busby-Spera, Cathy

1991-03-01

Laser probe 40Ar/39Ar analyses of individual sanidine grains from four tuffs in the alluvial Late Cretaceous (Campanian) El Gallo Formation yield statistically distinct mean dates ranging from 74.87±0.05 Ma to 73.59±0.09 Ma. The exceptional precision of these dates permits calculation of statistically significant sediment accumulation rates that are much higher than passive sediment loading would cause, implying rapid tectonically induced subsidence. The dates bracket tightly the age of important dinosaur and mammalian faunas previously reported from the El Gallo Formation. The dates support an age less than 73 Ma for the Campanian/Maastrichtian stage boundary, younger than indicated by several currently used time scales. Further application of the single grain 40Ar/39Ar technique may be expected to greatly benefit stratigraphic studies of Mesozoic sedimentary basins and contribute to calibration of biostratigraphic and magnetostratigraphic time scales.

Lens and dendrite formation during colloidal solidification

NASA Astrophysics Data System (ADS)

Worster, Grae; You, Jiaxue

2017-11-01

Colloidal particles in suspension are forced into a variety of morphologies when the suspending fluid medium is frozen: soil is compacted between ice lenses during frost heave; ice templating is a recent and growing technology to produce bio-inspired, micro-porous materials; cells and tissue can be damaged during cryosurgery; and metal-matrix composites with tailored microstructure can be fabricated by controlled casting. Various instabilities that affect the microscopic morphology are controlled by fluid flow through the compacted layer of particles that accumulates ahead of the solidification front. By analysing the flow in connection with equilibrium phase relationships, we develop a theoretical framework that identifies two different mechanisms for ice-lens formation, with and without a frozen fringe, identifies the external parameters that differentiates between them and the possibility of dendritic formations, and unifies a range of apparently disparate conclusions drawn from previous experimental studies. China Scholarship Council and the British Council.

Singular Isothermal Disks and the Formation of Multiple Stars

NASA Technical Reports Server (NTRS)

Galli, Daniele; Shu, Frank H.; Laughlin, Gregory; Lizano, Susana; DeVincenzi, Donald (Technical Monitor)

2000-01-01

A crucial missing ingredient in previous theoretical studies of fragmentation is the inclusion of dynamically important levels of magnetic fields. As a minimal model for a candidate presursor to the formation of binary and multiple stars, we therefore consider the equilibrium configuration of isopedically magnetized, scale-free, singular isothermal disks, without the assumption of axial symmetry. We find that lopsided (M = 1) configurations exist at any dimensionless rotation rate, including zero. Multiple-lobed (M = 2, 3, 4, ...) configurations bifurcate from an underlying axisymmetric sequence at progressively higher dimensionless rates of rotation, but such nonaxisymmetric sequences always terminate in shockwaves before they have a chance to fission into separate bodies. We advance the hypothesis that binary and multiple star-formation from smooth (i.e., not highly turbulent) starting states that are supercritical but in unstable mechanical balance requires the rapid (i.e., dynamical) loss of magnetic flux at some stage of the ensuing gravitational collapse.

Enzymic synthesis of γ-coniceine in Conium maculatum chloroplasts and mitochondria.

PubMed

Roberts, M F

1981-08-01

Further studies of the transaminase responsible for the first committed step in alkaloid formation in Conium maculatum have shown the L-alanine: 5-ketooctanal transaminase to occur in both the mitochondria and chloroplast. Experiments suggest that these enzymes are the isoenzymes Transaminase A and B respectively previously isolated by the author. It is suggested that the chloroplast enzyme is normally responsible for alkaloid production.

The Influence of Alternative Scale Formats on the Generalizability of Data Obtained from Direct Behavior Rating Single-Item Scales (DBR-SIS)

ERIC Educational Resources Information Center

Briesch, Amy M.; Kilgus, Stephen P.; Chafouleas, Sandra M.; Riley-Tillman, T. Chris; Christ, Theodore J.

2013-01-01

The current study served to extend previous research on scaling construction of Direct Behavior Rating (DBR) in order to explore the potential flexibility of DBR to fit various intervention contexts. One hundred ninety-eight undergraduate students viewed the same classroom footage but rated student behavior using one of eight randomly assigned…

Contributions of EspA filaments and curli fimbriae in cellular adherence and biofilm formation of enterohemorrhagic Escherichia coli O157:H7

USDA-ARS?s Scientific Manuscript database

In Escherichia coli O157:H7 (O157), the filamentous structure of the type III secretion system is produced from the polymerization of the EspA protein. EspA filaments are essential for O157 adherence to epithelial cells. In previous studies, we demonstrated that O157 hha deletion mutants showed incr...

The Space Infrared Interferometric Telescope (SPIRIT): Recent Study Results and Plans

NASA Astrophysics Data System (ADS)

Leisawitz, David; SPIRIT Mission Study Team

2007-12-01

SPIRIT was recommended in the 2002 "Community Plan for Far-IR/Submillimeter Space Astronomy.” A structurally connected interferometer, SPIRIT provides sensitive sub-arcsecond angular resolution images and integral field spectroscopy in the 25 to 400 micron wavelength range. SPIRIT was designed to revolutionize our understanding of planetary system formation, reveal otherwise-undetectable planets through the disk perturbations they induce, spectroscopically probe the atmospheres of extrasolar giant planets in orbits typical of most of the planets in our solar system, and yield significant new insight into the processes associated with galaxy formation and development. This paper updates previously presented study results and describes future study plans. Our SPIRIT mission concept study proposal was peer reviewed and selected by NASA for support under the Origins Probe Mission Concept Study program. NASA's Goddard Space Flight Center and four industry partners - Ball Aerospace, Boeing, Lockheed-Martin, and Northrop-Grumman - contributed generously the study. The Origins Probe study results were reviewed by an Advisory Review Panel.

Unconventional Constraints on Nitrogen Chemistry using DC3 Observations and Trajectory-based Chemical Modeling

NASA Astrophysics Data System (ADS)

Shu, Q.; Henderson, B. H.

2017-12-01

Chemical transport models underestimate nitrogen dioxide observations in the upper troposphere (UT). Previous research in the UT succeeded in combining model predictions with field campaign measurements to demonstrate that the nitric acid formation rate (HO + NO2 → HNO3 (R1)) is overestimated by 22% (Henderson et al., 2012). A subsequent publication (Seltzer et al., 2015) demonstrated that single chemical constraint alters ozone and aerosol formation/composition. This work attempts to replicate previous chemical constraints with newer observations and a different modeling framework. We apply the previously successful constraint framework to Deep Convection Clouds and Chemistry (DC3). DC3 is a more recent field campaign where simulated nitrogen imbalances still exist. Freshly convected air parcels, identified in the DC3 dataset, as initial coordinates to initiate Lagrangian trajectories. Along each trajectory, we simulate the air parcel chemical state. Samples along the trajectories will form ensembles that represent possible realizations of UT air parcels. We then apply Bayesian inference to constrain nitrogen chemistry and compare results to the existing literature. Our anticipated results will confirm overestimation of HNO3 formation rate in previous work and provide further constraints on other nitrogen reaction rate coefficients that affect terminal products from NOx. We will particularly focus on organic nitrate chemistry that laboratory literature has yet to fully address. The results will provide useful insights into nitrogen chemistry that affects climate and human health.

The Influence of Pseudomonas fluorescens on Corrosion Products of Archaeological Tin-Bronze Analogues

NASA Astrophysics Data System (ADS)

Ghiara, G.; Grande, C.; Ferrando, S.; Piccardo, P.

2018-01-01

In this study, tin-bronze analogues of archaeological objects were investigated in the presence of an aerobic Pseudomonas fluorescens strain in a solution, containing chlorides, sulfates, carbonates and nitrates according to a previous archaeological characterization. Classical fixation protocols were employed in order to verify the attachment capacity of such bacteria. In addition, classical metallurgical analytical techniques were used to detect the effect of bacteria on the formation of uncommon corrosion products in such an environment. Results indicate quite a good attachment capacity of the bacteria to the metallic surface and the formation of the uncommon corrosion products sulfates and sulfides is probably connected to the bacterial metabolism.

Star Formation in Orion A : Towards Resolved Maps of SFR and SFE

NASA Astrophysics Data System (ADS)

Großschedl, Josefa; Alves, J.; Ascenso, J.; Bouy, H.

2017-06-01

The OrionA GMC is a benchmark for studying star formation. Our goal is to construct a map of SFR and SFE (with Herschel) across the entire complex, for which it is critical to have a reliable and complete sample of YSOs. In this work we present a refined catalogue of YSOs, making use of a new deep NIR survey with VISTA, complemented with archival data. The survey allows us to rule out false positives from previous samples (galaxies, cloud edges, etc.). To add new candidates we use MIR data from WISE for areas not covered by Spitzer to get a complete census of the spatial distribution of YSOs.

Stabilization of Ag nanostructures by tuning their Fermi levels

NASA Astrophysics Data System (ADS)

Tani, Tadaaki; Kan, Ryota; Yamano, Yuka; Uchida, Takayuki

2018-05-01

The oxidation of Ag nanostructures has been studied as a key step for their degradation under the guiding principle in the previous paper that they are stable when their Fermi level is lower than those of their surroundings. The drop of the Fermi level of a thin Ag layer was caused by the formation of self-assembled monolayers (SAMs) of certain organic compounds including those of photographic interest and a monolayer of AgI, and attributed to the formation of dielectric layers, whose positive charges were closer to the Ag layer than negative charges. A consideration is given on further examinations needed to realize the above guiding principle in individual devices.

The Martian valley networks: Origin by niveo-fluvial processes

NASA Technical Reports Server (NTRS)

Rice, J. W., Jr.

1993-01-01

The valley networks may hold the key to unlocking the paleoclimatic history of Mars. These enigmatic landforms may be regarded as the Martian equivalent of the Rosetta Stone. Therefore, a more thorough understanding of their origin and evolution is required. However, there is still no consensus among investigators regarding the formation (runoff vs. sapping) of these features. Recent climatic modeling precludes warm (0 degrees C) globally averaged surface temperatures prior to 2 b.y. when solar luminosity was 25-30 percent less than present levels. This paper advocates snowmelt as the dominant process responsible for the formation of the dendritic valley networks. Evidence for Martian snowfall and subsequent melt has been discussed in previous studies.

An intra-abdominal abscess or "rind" as a consequence of peritoneal dialysis-associated pseudomonas peritonitis.

PubMed

Culpepper, R Michael; Gore, Sarah; Rutecki, Gregory W

2013-01-01

Abdominal CT imaging has defined characteristics of two pathological entities specific to peritoneal dialysis patients. Both are associated with serious peritoneal complications. One is comprised of ascites accompanied by septation and loculated fluid pockets as a complication of bacterial peritonitis. The other is the syndrome of encapsulating peritoneal sclerosis. We present the evolution of a single, thick-walled fluid collection as a consequence of relapsing Pseudomonas aeruginosa peritonitis. The entity had distinctive features differing from either of the two previously described entities, and to our knowledge, has not been described previously. Our patient's radiological evolution resembled the formation of a pleural or peritoneal "rind." Peritonitis, as a result of Pseudomonas aeruginosa , may lead to "rind" formation as described with empyemas and is distinct from previously described intra-abdominal pathologies in peritoneal dialysis patients.

Preliminary appraisal of gravity and magnetic data of Syncline Ridge, western Yucca Flat, Nevada Test Site, Nye County, Nevada

USGS Publications Warehouse

Ponce, David A.; Hanna, William F.

1982-01-01

A gravity and magnetic study of the Syncline Ridge area was conducted as part of an investigation of argillite rocks of the Eleana Formation under consideration as a medium for the possible storage of high-level radioactive waste. Bouguer gravity anomaly data, viewed in light of densities obtained by gamma-gamma logs and previous work of D. L. Healey (1968), delineate two regions of steep negative gradient where Cenozoic rocks and sediments are inferred to abruptly thicken: (1) the western third of the study area where Tertiary volcanic rocks are extensively exposed and (2) the northeast corner of the area where Quaternary alluvium is exposed and where volcanic rocks are inferred to occur at depth. In the remainder of the area, a region extending contiguously from Mine Mountain northwestward through Syncline Ridge to the Eleana Range, the gravity data indicate that the Eleana Formation, where not exposed, is buried at depths of less than about 200 m, except in a limited area of exposed older Paleozoic rocks on Mine Mountain. Quaternary alluvium and Tertiary volcanic rocks are inferred to occur in this region as veneers or shallow dishes of deposit on Tippipah Limestone or Eleana Formation. Low-level aeromagnetic anomaly data, covering the western two-thirds of the study area, delineate relatively magnetic tuff units within the Tertiary volcanic rocks and provide a very attractive means for distinguishing units of normal polarization from units of reversed polarization. If used in conjunction with results of previous magnetization studies of G. D. Bath (1968), the low-level survey may prove to be an effective tool for mapping specific tuff members in the volcanic terrane. The important question of the feasibility of discriminating high-quartz argillite from low-quartz argillite of the Eleana Formation using surface gravity data remains unresolved. If the more highly competent, denser, high-quartz phase should occur as stratigraphic units many tens of meters thick, closely spaced gravity data may reliably detect these units. If the high-quartz phase occurs only as relatively thin units, interbedded with low-quartz phase, borehole gravity surveying can be used much more effectively than equivalent surface gravity surveying.

Millimeter Wave Spectrum and Astronomical Search for Vinyl Formate

NASA Astrophysics Data System (ADS)

Alonso, E. R.; Kolesniková, L.; Tercero, B.; Cabezas, C.; Alonso, J. L.; Cernicharo, J.; Guillemin, J.-C.

2016-11-01

Previous detections of methyl and ethyl formate make other small substituted formates potential candidates for observation in the interstellar medium. Among them, vinyl formate is one of the simplest unsaturated carboxylic ester. The aim of this work is to provide direct experimental frequencies of the ground vibrational state of vinyl formate in a large spectral range for astrophysical use. The room-temperature rotational spectrum of vinyl formate has been measured from 80 to 360 GHz and analyzed in terms of Watson’s semirigid rotor Hamiltonian. Two thousand six hundred transitions within J = 3-88 and K a = 0-28 were assigned to the most stable conformer of vinyl formate and a new set of spectroscopic constants was accurately determined. Spectral features of vinyl formate were then searched for in Orion KL, Sgr B2(N), B1-b, and TMC-1 molecular clouds. Upper limits to the column density of vinyl formate are provided.

A revision of the Norian Conchostracan Zonation in North America and its implications for Late Triassic North American tectonic history

USGS Publications Warehouse

Weems, Robert E.; Lucas, Spencer G.

2015-01-01

Collections of Upper Triassic (Norian) conchostracans from the upper Cumnock and lower Sanford formations (North Carolina), Bull Run Formation (Virginia), Gettysburg Formation (Pennsylvania), Passaic Formation (New Jersey), Blomidon Formation (Nova Scotia), and Redonda Formation (New Mexico) have significantly expanded our knowledge of the Norian conchostracan faunas in these units. These collections show that the temporal and spatial distribution of Norian conchostracans in North America is more complex and more environmentally controlled than previously thought. The new collections require a revision and simplification of the published conchostracan zonation for this interval. The revised zonation, based almost entirely on evolution within the lineage of the conchostracan genus Shipingia, consists of five zones: the Shipingia weemsi-Euestheria buravasi zone (Lacian), the Shipingia mcdonaldi zone (lower Alaunian), the Shipingia hebaozhaiensis zone (upper Alaunian), the Shipingia olseni zone (lower and middle Sevatian), and the Shipingia gerbachmanni zone (upper Sevatian). A new species of Norian conchostracan, Wannerestheria kozuri, is described from the Groveton Member of the Bull Run Formation (Virginia). Two new members (Plum Run and Fairfield members) are named in the Gettysburg Formation (Gettysburg Basin, Maryland and Pennsylvania). The distribution of upper Carnian and Norian strata in the Fundy, Newark, Gettysburg, and Culpeper basins indicates that there was a significant, previously undetected tectonic reorganization within these basins that occurred around the Carnian-Norian boundary. The presence of an upper Norian-lower Rhaetian unconformity within the Newark Supergroup is reaffirmed. A re-evaluation of the conchostracan record from the Redonda Formation of the Chinle Group in New Mexico indicates that the four conchostracan-bearing lacustrine beds in this unit are part of only a single, consistently recognizable conchostracan zone, which we here designate as the Shipingia gerbachmanni zone.

Analysis of incidence of bulla formation after tattoo treatment using the combination of the picosecond Alexandrite laser and fractionated CO2 ablation.

PubMed

Au, Sonoa; Liolios, Ana M; Goldman, Mitchel P

2015-02-01

The picosecond Alexandrite laser has shown increased efficacy in tattoo removal in comparison to Q-switched lasers. However, bulla formation is a well-known and expected side effect of this novel treatment and causes patient discomfort. To analyze the incidence of bulla formation after tattoo treatment using the combination of the picosecond Alexandrite laser and fractionated CO2 ablation. This is a retrospective chart review to determine the incidence of bulla formation after laser tattoo removal in 95 patients who were treated with either with the picosecond Alexandrite laser alone or in combination with fractional CO2 ablation. Twenty-six patients (32%) treated with the picosecond laser alone experienced blistering, whereas none of the patients treated with the combination of the picosecond laser and fractionated CO2 ablation experienced blistering. The difference in incidence of bulla formation between the 2 groups was found to be statistically significant (p < .05). This study shows a significant decrease in bulla formation associated with tattoo treatment when fractionated CO2 ablation is added to the picosecond Alexandrite laser, which is consistent with observations from a previous case series. This is important because decreasing extensive blistering likely results in increased patient satisfaction and willingness to return for future treatments.

BETAINE PREVENTS MALLORY-DENK BODY FORMATION IN DRUG-PRIMED MICE BY EPIGENETIC MECHANISMS

PubMed Central

Oliva, Joan; Bardag-Gorce, Fawzia; Li, Jun; French, Barbara A; Nguyen, Sheila K.; Lu, Shelly C.; French, Samuel W.

2012-01-01

Previous studies showed that S-Adenosylmethionine (SAMe) prevented MDB formation and the hypomethylation of histones induced by DDC feeding. These results suggest that formation of MDBs is an epigenetic phenomenon. To further test this theory, drug-primed mice were fed the methyl donor, betaine, together with DDC, which was refed for 7 days. Betaine significantly reduced MDB formation, decreased the liver/body weight ratio and decreased the number of FAT10 positive liver cells when they proliferate in response to DDC refeeding. Betaine also significantly prevented the decreased expression of BHMT, AHCY, MAT1a and GNMT and the increased expression of MTHFR, caused by DDC refeeding. S-Adenosylhomocysteine (SAH) levels were reduced by DDC refeeding and this was prevented by betaine. The results support the concept that betaine donates methyl groups, increasing methionine available in the cell. SAMe metabolism was reduced by the decrease in GNMT expression, which prevented the conversion of SAMe to SAH. As a consequence, betaine prevented MDB formation and FAT10 positive cell proliferation by blocking the epigenetic memory expressed by hepatocytes. The results further support the concept that MDB formation is the result of an epigenetic phenomenon, where a change in methionine metabolism causes global gene expression changes in hepatocytes. PMID:19073172

Crystalline structures of particles interacting through the harmonic-repulsive pair potential

NASA Astrophysics Data System (ADS)

Levashov, V. A.

2017-09-01

The behavior of identical particles interacting through the harmonic-repulsive pair potential has been studied in 3D using molecular dynamics simulations at a number of different densities. We found that at many densities, as the temperature of the systems decreases, the particles crystallize into complex structures whose formation has not been anticipated in previous studies on the harmonic-repulsive pair potential. In particular, at certain densities, crystallization into the structure I a 3 ¯ d (space group #230) with 16 particles in the unit cell occupying Wyckoff special positions (16b) was observed. This crystal structure has not been observed previously in experiments or in computer simulations of single component atomic or soft matter systems. At another density, we observed a liquid which is rather stable against crystallization. Yet, we observed crystallization of this liquid into the monoclinic C2/c (space group #15) structure with 32 particles in the unit cell occupying four different non-special Wyckoff (8f) sites. In this structure particles located at different Wyckoff sites have different energies. From the perspective of the local atomic environment, the organization of particles in this structure resembles the structure of some columnar quasicrystals. At a different value of the density, we did not observe crystallization at all despite rather long molecular dynamics runs. At two other densities, we observed the formation of the β S n distorted diamond structures instead of the expected diamond structure. Possibly, we also observed the formation of the R 3 ¯ c hexagonal lattice with 24 particles per unit cell occupying non-equivalent positions.

Suppressed bone remodeling in black bears conserves energy and bone mass during hibernation

PubMed Central

McGee-Lawrence, Meghan; Buckendahl, Patricia; Carpenter, Caren; Henriksen, Kim; Vaughan, Michael; Donahue, Seth

2015-01-01

ABSTRACT Decreased physical activity in mammals increases bone turnover and uncouples bone formation from bone resorption, leading to hypercalcemia, hypercalcuria, bone loss and increased fracture risk. Black bears, however, are physically inactive for up to 6 months annually during hibernation without losing cortical or trabecular bone mass. Bears have been shown to preserve trabecular bone volume and architectural parameters and cortical bone strength, porosity and geometrical properties during hibernation. The mechanisms that prevent disuse osteoporosis in bears are unclear as previous studies using histological and serum markers of bone remodeling show conflicting results. However, previous studies used serum markers of bone remodeling that are known to accumulate with decreased renal function, which bears have during hibernation. Therefore, we measured serum bone remodeling markers (BSALP and TRACP) that do not accumulate with decreased renal function, in addition to the concentrations of serum calcium and hormones involved in regulating bone remodeling in hibernating and active bears. Bone resorption and formation markers were decreased during hibernation compared with when bears were physically active, and these findings were supported by histomorphometric analyses of bone biopsies. The serum concentration of cocaine and amphetamine regulated transcript (CART), a hormone known to reduce bone resorption, was 15-fold higher during hibernation. Serum calcium concentration was unchanged between hibernation and non-hibernation seasons. Suppressed and balanced bone resorption and formation in hibernating bears contributes to energy conservation, eucalcemia and the preservation of bone mass and strength, allowing bears to survive prolonged periods of extreme environmental conditions, nutritional deprivation and anuria. PMID:26157160

Comparison between flipped classroom and team-based learning in fixed prosthodontic education.

PubMed

Nishigawa, Keisuke; Omoto, Katsuhiro; Hayama, Rika; Okura, Kazuo; Tajima, Toyoko; Suzuki, Yoshitaka; Hosoki, Maki; Shigemoto, Shuji; Ueda, Mayu; Rodis, Omar Marianito Maningo; Matsuka, Yoshizo

2017-04-01

We previously investigated the effects of team-based learning (TBL) on fixed prosthodontic education and reported that TBL could have higher efficiency with high student satisfaction than traditional lecture. In the current report, we introduced flipped classroom to the fixed prosthodontic education and compared their effectiveness based on the final examination score in addition to TBL. Participants were 41 students from Tokushima University School of Dentistry who attended a fixed prosthodontics course. The first six classes adopted the flipped classroom style while the latter eight classes adopted TBL. To evaluate the relationship between learning styles and their effectiveness, we compared results from the term-end examination between the curriculum covered by flipped classroom and TBL-style classes. To draw comparisons, a referential examination with the same questions was conducted to eight faculty members who had not attended any of these classes. Term-end examination results showed that TBL classes had slightly higher scores than flipped classroom classes. Referential examination results also showed higher scores for the same curriculum and no significant interaction was found between class formats and the term-end and referential examination scores. Analysis revealed no noticeable difference in the effectiveness of the class formats. Our previous study reported that TBL had higher efficiency than traditional style lecture. In the current study, there was no statistical difference in the examination score between flipped classroom and TBL. Therefore, we conclude that both styles are highly effective than traditional style lecture and constitute valid formats for clinical dental education. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

The JCMT Nearby Galaxies Legacy Survey - VII. Hα imaging and massive star formation properties

NASA Astrophysics Data System (ADS)

Sánchez-Gallego, J. R.; Knapen, J. H.; Wilson, C. D.; Barmby, P.; Azimlu, M.; Courteau, S.

2012-06-01

We present Hα fluxes, star formation rates (SFRs) and equivalent widths (EWs) for a sample of 156 nearby galaxies observed in the 12CO J= 3-2 line as part of the James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey. These are derived from images and values in the literature and from new Hα images for 72 galaxies which we publish here. We describe the sample, observations and procedures to extract the Hα fluxes and related quantities. We discuss the SFR properties of our sample and confirm the well-known correlation with galaxy luminosity, albeit with high dispersion. Our SFRs range from 0.1 to 11 M⊙ yr-1 with a median SFR value for the complete sample of 0.2 M⊙ yr-1. This median value is somewhat lower than similar published measurements, which we attribute, in part, to our sample being H I selected and, thus, not biased towards high SFRs as has frequently been the case in previous studies. Additionally, we calculate internal absorptions for the Hα line, A(Hα), which are lower than many of those used in previous studies. Our derived EWs, which range from 1 to 880 Å with a median value of 27 Å, show little dependence on luminosity but rise by a factor of 5 from early- to late-type galaxies. This paper is the first in a series aimed at comparing SFRs obtained from Hα imaging of galaxies with information derived from other tracers of star formation and atomic and molecular gas.

Mechanisms of fenthion activation in rainbow trout (Oncorhynchus mykiss) acclimated to hypersaline environments

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

Lavado, Ramon; Rimoldi, John M.; Schlenk, Daniel

2009-03-01

Previous studies in rainbow trout have shown that acclimation to hypersaline environments enhances the toxicity to thioether organophosphate and carbamate pesticides. In order to determine the role of biotransformation in this process, the metabolism of the thioether organophosphate biocide, fenthion was evaluated in microsomes from gills, liver and olfactory tissues in rainbow trout (Oncorhynchus mykiss) acclimated to freshwater and 17 per mille salinity. Hypersalinity acclimation increased the formation of fenoxon and fenoxon sulfoxide from fenthion in liver microsomes from rainbow trout, but not in gills or in olfactory tissues. NADPH-dependent and independent hydrolysis was observed in all tissues, but onlymore » NADPH-dependent fenthion cleavage was differentially modulated by hypersalinity in liver (inhibited) and gills (induced). Enantiomers of fenthion sulfoxide (65% and 35% R- and S-fenthion sulfoxide, respectively) were formed in liver and gills. The predominant pathway of fenthion activation in freshwater appears to be initiated through initial formation of fenoxon which may be subsequently converted to the most toxic metabolite fenoxon R-sulfoxide. However, in hypersaline conditions both fenoxon and fenthion sulfoxide formation may precede fenoxon sulfoxide formation. Stereochemical evaluation of sulfoxide formation, cytochrome P450 inhibition studies with ketoconazole and immunoblots indicated that CYP3A27 was primarily involved in the enhancement of fenthion activation in hypersaline-acclimated fish with limited contribution of FMO to initial sulfoxidation.« less

Insight into the effect of promoter Co on C2 oxygenate formation from syngas on CoCu(100) and Cu(100): A comparative DFT study

NASA Astrophysics Data System (ADS)

Sun, Xuanyu; Yu, Yingzhe; Zhang, Minhua

2018-03-01

Density functional theory calculations have been employed to investigate the effect of promoter Co on C2 oxygenate formation from syngas on pure Cu(100) and two kinds of Co-Cu bimetallic surfaces. Based on the results of previous studies that CH3O is a key intermediate in ethanol formation on Cu catalyst, five reactions starting from CH3O were taken into consideration. Different from the results on Cu(100) that CH3OH is the most favorable product on pure Co sites, CH3 formation is more favorable both kinetically and thermodynamically than CH3OH formation, which leads to more CH3 available for CHO insertion to form C2 oxygenates. On the other hand, Co-Cu bimetallic sites can facilitate CHO insertion into CH3 energetically, which is favorable for carbon chain growth. And the addition of Co can make the barrier of CH3 hydrogenation and CH3 coupling to CH4 and CH3CH3 higher, making CH3CHO much more selective than hydrocarbons. In conclusion, by introducing Co into Cu catalyst, the productivity and selectivity of C2 oxygenate precursor of ethanol can be effectively improved. The optimum Co-Cu catalyst should contain Cu ensembles and Co ensembles with proper sizes, and offer enough Co-Cu bimetallic sites at the same time.

Type 4 pili are dispensable for biofilm development in the cyanobacterium Synechococcus elongatus.

PubMed

Nagar, Elad; Zilberman, Shaul; Sendersky, Eleonora; Simkovsky, Ryan; Shimoni, Eyal; Gershtein, Diana; Herzberg, Moshe; Golden, Susan S; Schwarz, Rakefet

2017-07-01

The hair-like cell appendages denoted as type IV pili are crucial for biofilm formation in diverse eubacteria. The protein complex responsible for type IV pilus assembly is homologous with the type II protein secretion complex. In the cyanobacterium Synechococcus elongatus PCC 7942, the gene Synpcc7942_2071 encodes an ATPase homologue of type II/type IV systems. Here, we report that inactivation of Synpcc7942_2071 strongly affected the suite of proteins present in the extracellular milieu (exo-proteome) and eliminated pili observable by electron microscopy. These results support a role for this gene product in protein secretion as well as in pili formation. As we previously reported, inactivation of Synpcc7942_2071 enables biofilm formation and suppresses the planktonic growth of S. elongatus. Thus, pili are dispensable for biofilm development in this cyanobacterium, in contrast to their biofilm-promoting function in type IV pili-producing heterotrophic bacteria. Nevertheless, pili removal is not required for biofilm formation as evident by a piliated mutant of S. elongatus that develops biofilms. We show that adhesion and timing of biofilm development differ between the piliated and non-piliated strains. The study demonstrates key differences in the process of biofilm formation between cyanobacteria and well-studied type IV pili-producing heterotrophic bacteria. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Radiative and Kinetic Feedback by Low-Mass Primordial Stars

NASA Astrophysics Data System (ADS)

Whalen, Daniel; Hueckstaedt, Robert M.; McConkie, Thomas O.

2010-03-01

Ionizing UV radiation and supernova (SN) flows amidst clustered minihalos at high redshift regulated the rise of the first stellar populations in the universe. Previous studies have addressed the effects of very massive primordial stars on the collapse of nearby halos into new stars, but the absence of the odd-even nucleosynthetic signature of pair-instability SNe in ancient metal-poor stars suggests that Population III stars may have been less than 100 M sun. We extend our earlier survey of local UV feedback on star formation to 25-80 M sun stars and include kinetic feedback by SNe for 25-40 M sun stars. We find radiative feedback to be relatively uniform over this mass range, primarily because the larger fluxes of more massive stars are offset by their shorter lifetimes. Our models demonstrate that prior to the rise of global UV backgrounds, Lyman-Werner (LW) photons from nearby stars cannot prevent halos from forming new stars. These calculations also reveal that violent dynamical instabilities can erupt in the UV radiation front enveloping a primordial halo, but that they ultimately have no effect on the formation of a star. Finally, our simulations suggest that relic H II regions surrounding partially evaporated halos may expel LW backgrounds at lower redshifts, allowing stars to form that were previously suppressed. We provide fits to radiative and kinetic feedback on star formation for use in both semianalytic models and numerical simulations.

Space charge effects on the third order coupled resonance

NASA Astrophysics Data System (ADS)

Franchetti, Giuliano; Gilardoni, Simone; Huschauer, Alexander; Schmidt, Frank; Wasef, Raymond

2017-08-01

The effect of space charge on bunched beams has been the subject of numerous numerical and experimental studies in the first decade of 2000. Experimental campaigns performed at the CERN Proton Synchrotron in 2002 and at the GSI SIS18 in 2008 confirmed the existence of an underlying mechanism in the beam dynamics of periodic resonance crossing induced by the synchrotron motion and space charge. In this article we present an extension of the previous studies to describe the effect of space charge on a controlled coupled (2D) third order resonance. The experimental and simulation results of this latest campaign shed a new light on the difficulties of the 2D particle dynamics. We find striking experimental evidence that space charge and the coupled resonance create an unusual coupling in the phase space, leading to the formation of an asymmetric halo. Moreover, this study demonstrates a clear link between halo formation and fixed-lines.

Silicification of trace fossils in carbonates; evidence from Permian Kaibab Formation, southwestern Utah

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

Whidden, K.J.; Bottjer, D.J.

Silicification in carbonates, particularly silicified trace fossils, has received relatively little previous study. Chert comprises a significant percentage of the upper Fossil Mountain Member of the Kaibab Formation, a Permian epicontinental limestone. Distribution and origin of this chert were studied from outcrops in southwestern Utah. The origin of much of this chert is believed to be as silicified Thalassinoides burrows. Field evidence for trace fossil silicification includes (1) silicified cylindrical tubes with Y-shaped branching patterns as well as hollow tubes, and (2) polygonal box-work patterns of tubes. In addition, brachiopods, bryozoans, and abundant specimens of the sponge Actinocelia maendrina Finksmore » are also silicified. Recognition of silicified trace fossils in carbonates provides a different approach to the study of early diagenetic silica precipitation. These silicified trace fossils also represent new information on bioturbation in ancient carbonates, a subject that has, until recently, been relatively unstudied.« less

Mutations of RNA splicing factors in hematological malignancies.

PubMed

Shukla, Girish C; Singh, Jagjit

2017-11-28

Systematic large-scale cancer genomic studies have produced numerous significant findings. These studies have not only revealed new cancer-promoting genes, but they also have identified cancer-promoting functions of previously known "housekeeping" genes. These studies have identified numerous mutations in genes which play a fundamental role in nuclear precursor mRNA splicing. Somatic mutations and copy number variation in many of the splicing factors which participate in the formation of multiple spliceosomal complexes appear to play a role in many cancers and in particular in myelodysplastic syndromes (MDS). Mutated proteins seem to interfere with the recognition of the authentic splice sites (SS) leading to utilization of suboptimal alternative splicing sites generating aberrantly spliced mRNA isoforms. This short review is focusing on the function of the splice factors involved in the formation of splicing complexes and potential mechanisms which affect usage of the authentic splice site recognition. Copyright © 2017 Elsevier B.V. All rights reserved.

The scanning cryomacroscope - A device prototype for the study of cryopreservation

NASA Astrophysics Data System (ADS)

Feig, Justin S. G.; Rabin, Yoed

2014-07-01

A new cryomacroscope prototype-a visualization device for the in situ analysis of cryopreserved biological samples-is presented in the current study. In order to visualize samples larger than the field of view of the optical setup, a scanning mechanism is integrated into the system, which represents a key improvement over previous cryomacroscope prototypes. Another key feature of the new design is in its compatibility with available top-loading controlled-rate cooling chambers, which eliminates the need for a dedicated cooling mechanism. The objective for the current development is to create means to generate a single digital movie of an experimental investigation, with all relevant data overlaid. The visualization capabilities of the scanning cryomacroscope are demonstrated in the current study on the cryoprotective agent dimethyl sulfoxide and the cryoprotective cocktail DP6. Demonstrated effects include glass formation, various regimes of crystallization, thermal contraction, and fracture formation.

Dynamic model based on voltage transfer curve for pattern formation in dielectric barrier glow discharge

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

Li, Ben; He, Feng; Ouyang, Jiting, E-mail: jtouyang@bit.edu.cn

2015-12-15

Simulation work is very important for understanding the formation of self-organized discharge patterns. Previous works have witnessed different models derived from other systems for simulation of discharge pattern, but most of these models are complicated and time-consuming. In this paper, we introduce a convenient phenomenological dynamic model based on the basic dynamic process of glow discharge and the voltage transfer curve (VTC) to study the dielectric barrier glow discharge (DBGD) pattern. VTC is an important characteristic of DBGD, which plots the change of wall voltage after a discharge as a function of the initial total gap voltage. In the modeling,more » the combined effect of the discharge conditions is included in VTC, and the activation-inhibition effect is expressed by a spatial interaction term. Besides, the model reduces the dimensionality of the system by just considering the integration effect of current flow. All these greatly facilitate the construction of this model. Numerical simulations turn out to be in good accordance with our previous fluid modeling and experimental result.« less

Differential regulation of polarized synaptic vesicle trafficking and synapse stability in neural circuit rewiring in Caenorhabditis elegans

PubMed Central

Kurup, Naina; Kono, Karina

2017-01-01

Neural circuits are dynamic, with activity-dependent changes in synapse density and connectivity peaking during different phases of animal development. In C. elegans, young larvae form mature motor circuits through a dramatic switch in GABAergic neuron connectivity, by concomitant elimination of existing synapses and formation of new synapses that are maintained throughout adulthood. We have previously shown that an increase in microtubule dynamics during motor circuit rewiring facilitates new synapse formation. Here, we further investigate cellular control of circuit rewiring through the analysis of mutants obtained in a forward genetic screen. Using live imaging, we characterize novel mutations that alter cargo binding in the dynein motor complex and enhance anterograde synaptic vesicle movement during remodeling, providing in vivo evidence for the tug-of-war between kinesin and dynein in fast axonal transport. We also find that a casein kinase homolog, TTBK-3, inhibits stabilization of nascent synapses in their new locations, a previously unexplored facet of structural plasticity of synapses. Our study delineates temporally distinct signaling pathways that are required for effective neural circuit refinement. PMID:28636662

Critical assessment of the formation of hydrogen peroxide in dough by fermenting yeast cells.

PubMed

Rezaei, Mohammad N; Dornez, Emmie; Verstrepen, Kevin J; Courtin, Christophe M

2015-02-01

Fermentation of bread dough leads to strengthening of the dough matrix. This effect has previously been ascribed to the action of hydrogen peroxide (H2O2) produced by yeast in dough. In this study, we re-evaluate the production of H2O2 by yeast in dough and aqueous fermentation broth. Results show that the previously reported high levels of H2O2 in fermenting dough were most probably due to the lack of specificity of the potassium dichromate/acetic acid-based method used. Using the chemiluminescent HyPerBlu assay, no yeast H2O2 production could be detected in fermented dough or broth. Even though the formation of low levels of H2O2 cannot be ruled out due to the presence of catalase in flour and the fast reaction of H2O2 with gluten proteins, our results suggest that the changes in dough matrix rheological properties upon fermentation are not due to production of H2O2 by yeast. Copyright © 2014 Elsevier Ltd. All rights reserved.

The closed MTIP-MyosinA-tail complex from the malaria parasite invasion machinery

PubMed Central

Bosch, Jürgen; Turley, Stewart; Roach, Claudia M.; Daly, Thomas M.; Bergman, Lawrence W.; Hol, Wim G. J.

2009-01-01

The Myosin A-tail Interacting Protein (MTIP) of the malaria parasite links the actomyosin motor of the host cell invasion machinery to its inner membrane complex. We report here that at neutral pH Plasmodium falciparum MTIP in complex with Myosin A adopts a compact conformation, with its two domains completely surrounding the Myosin A-tail helix, dramatically different from previously observed extended MTIP structures. Crystallographic and mutagenesis studies show that H810 and K813 of Myosin A are key players in the formation of the compact MTIP:Myosin A complex. Only the unprotonated state of Myosin A-H810 is compatible with the compact complex. Most surprisingly, every side chain atom of Myosin A-K813 is engaged in contacts with MTIP. While this side chain was previously considered to prevent a compact conformation of MTIP with Myosin A, it actually appears to be essential for the formation of the compact complex. The hydrophobic pockets and adaptability seen in the available series of MTIP structures bodes well for the discovery of inhibitors of cell invasion by malaria parasites. PMID:17628590

Refinement of determination of critical thresholds of stress-strain behaviour by using AE data: potential for evaluation of durability of natural stone

NASA Astrophysics Data System (ADS)

Prikryl, Richard; Lokajíček, Tomáš

2017-04-01

According to previous studies, evaluation of stress-strain behaviour (in uniaxial compression) of various rocks appears to be effective tool allowing for prediction of resistance of natural stone to some physical weathering processes. Precise determination of critical thresholds, specifically of 'crack initiation' and 'crack damage' is fundamental issue in this approach. In contrast to 'crack damage stress/strain threshold', which can be easily read from deflection point on volumetric curve, detection of 'crack initiation' is much more difficult. Besides previously proposed mathematical processing of axial stress-strain curve, recording of acoustic emission (AE) data and their processing provide direct measure of various stress/strain thresholds, specifically of 'crack initiation'. This specific parameter is required during successive computation of energetic parameters (mechanical work), that can be stored by a material without formation of new defects (microcracks) due to acting stress. Based on our experimental data, this mechanical work seems to be proportional to the resistance of a material to formation of mode I (tensile) cracks that are responsible for destruction of subsurface below exposed faces of natural stone.

NF-κB RelB Negatively Regulates Osteoblast Differentiation and Bone Formation

PubMed Central

Yao, Zhenqiang; Li, Yanyun; Yin, Xiaoxiang; Dong, Yufeng; Xing, Lianping; Boyce, Brendan F.

2013-01-01

RelA-mediated NF-κB canonical signaling promotes mesenchymal progenitor cell (MPC) proliferation, but inhibits differentiation of mature osteoblasts (OBs) and thus negatively regulates bone formation. Previous studies suggest that NF-κB RelB may also negatively regulate bone formation through non-canonical signaling, but they involved a complex knockout mouse model and the molecular mechanisms involved were not investigated. Here, we report that RelB−/− mice develop age-related increased trabecular bone mass associated with increased bone formation. RelB−/− bone marrow stromal cells expanded faster in vitro and have enhanced OB differentiation associated with increased expression of the osteoblastogenic transcription factor, Runx2. In addition, RelB directly targeted the Runx2 promoter to inhibit its activation. Importantly, RelB−/− bone-derived MPCs formed bone more rapidly than wild-type cells after they were injected into a murine tibial bone defect model. Our findings indicate that RelB negatively regulates bone mass as mice age and limits bone formation in healing bone defects, suggesting that inhibition of RelB could reduce age-related bone loss and enhance bone repair. PMID:24115294

Few-body modes of binary formation in core collapse

NASA Astrophysics Data System (ADS)

Tanikawa, Ataru; Heggie, Douglas C.; Hut, Piet; Makino, Junichiro

2013-11-01

At the moment of deepest core collapse, a star cluster core contains less than ten stars. This small number makes the traditional treatment of hard binary formation, assuming a homogeneous background density, suspect. In a previous paper, we have found that indeed the conventional wisdom of binary formation, based on three-body encounters, is incorrect. Here we refine that insight, by further dissecting the subsequent steps leading to hard binary formation. For this purpose, we add some analysis tools in order to make the study less subjective. We find that the conventional treatment does remain valid for direct three-body scattering, but fails for resonant three-body scattering. Especially democratic resonance scattering, which forms an important part of the analytical theory of three-body binary formation, takes too much space and time to be approximated as being isolated, in the context of a cluster core around core collapse. We conclude that, while three-body encounters can be analytically approximated as isolated, subsequent strong perturbations typically occur whenever those encounters give rise to democratic resonances. We present analytical estimates postdicting our numerical results. If we only had been a bit more clever, we could have predicted this qualitative behaviour.

The hippocampal formation: morphological changes induced by thyroid, gonadal and adrenal hormones.

PubMed

Gould, E; Woolley, C S; McEwen, B S

1991-01-01

The hippocampal formation is of considerable interest due to its proposed role in a number of important functions, including learning and memory processes. Manipulations of thyroid, gonadal and adrenal hormones have been shown to influence hippocampal physiology as well as learning and memory. The cellular events which underlie these hormone-induced functional changes are largely unexplored. However, studies suggest that hormonal manipulations during development and in adulthood result in dramatic morphological changes within the hippocampal formation. Because neuronal physiology has been suggested to depend upon neuronal morphology, we have been determining the morphologic sensitivity of hippocampal neurons to thyroid and steroid hormones in an effort to elucidate possible structural mechanisms to account for differences in hippocampal function. In this review, hormone-induced structural changes in the developing and adult hippocampal formation are discussed, with particular emphasis on their functional relevance. Sex differences, as well as the developmental effects of thyroid hormone and glucocorticoids, are described. Moreover, the effects of ovarian steroids, thyroid hormone and glucocorticoids on neuronal morphology in the hippocampal formation of the adult rat are reviewed. These hormone-induced structural changes may account, at least in part, for previously reported hormone-induced changes in hippocampal function.

Neonatal Treatment with a Pegylated Leptin Antagonist Induces Sexually Dimorphic Effects on Neurones and Glial Cells, and on Markers of Synaptic Plasticity in the Developing Rat Hippocampal Formation.

PubMed

López-Gallardo, M; Antón-Fernández, A; Llorente, R; Mela, V; Llorente-Berzal, A; Prada, C; Viveros, M P

2015-08-01

The present study aimed to better understand the role of the neonatal leptin surge, which peaks on postnatal day (PND)9-10, on the development of the hippocampal formation. Accordingly, male and female rats were administered with a pegylated leptin antagonist on PND9 and the expression of neurones, glial cells and diverse markers of synaptic plasticity was then analysed by immunohistochemistry in the hippocampal formation. Antagonism of the actions of leptin at this specific postnatal stage altered the number of glial fibrillary acidic protein positive cells, and also affected type 1 cannabinoid receptors, synaptophysin and brain-derived neurotrophic factor (BDNF), with the latter effect being sexually dimorphic. The results indicate that the physiological leptin surge occurring around PND 9-10 is critical for hippocampal formation development and that the dynamics of leptin activity might be different in males and females. The data obtained also suggest that some but not all the previously reported effects of maternal deprivation on hippocampal formation development (which markedly reduces leptin levels at PND 9-10) might be mediated by leptin deficiency in these animals. © 2015 British Society for Neuroendocrinology.

Influence of the formation- and passivation rate of boron-oxygen defects for mitigating carrier-induced degradation in silicon within a hydrogen-based model

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

Hallam, Brett, E-mail: brett.hallam@unsw.edu.au; Abbott, Malcolm; Nampalli, Nitin

2016-02-14

A three-state model is used to explore the influence of defect formation- and passivation rates of carrier-induced degradation related to boron-oxygen complexes in boron-doped p-type silicon solar cells within a hydrogen-based model. The model highlights that the inability to effectively mitigate carrier-induced degradation at elevated temperatures in previous studies is due to the limited availability of defects for hydrogen passivation, rather than being limited by the defect passivation rate. An acceleration of the defect formation rate is also observed to increase both the effectiveness and speed of carrier-induced degradation mitigation, whereas increases in the passivation rate do not lead tomore » a substantial acceleration of the hydrogen passivation process. For high-throughput mitigation of such carrier-induced degradation on finished solar cell devices, two key factors were found to be required, high-injection conditions (such as by using high intensity illumination) to enable an acceleration of defect formation whilst simultaneously enabling a rapid passivation of the formed defects, and a high temperature to accelerate both defect formation and defect passivation whilst still ensuring an effective mitigation of carrier-induced degradation.« less

Nitric oxide in B6 mouse and nitric oxide-sensitive soluble guanylate cyclase in cat modulate acetylcholine release in pontine reticular formation.

PubMed

Lydic, Ralph; Garza-Grande, Ricardo; Struthers, Richard; Baghdoyan, Helen A

2006-05-01

ACh regulates arousal, and the present study was designed to provide insight into the neurochemical mechanisms modulating ACh release in the pontine reticular formation. Nitric oxide (NO)-releasing beads microinjected into the pontine reticular formation of C57BL/6J (B6) mice significantly (P < 0.0001) increased ACh release. Microdialysis delivery of the NO donor N-ethyl-2-(1-ethyl-2-hydroxy-2-nitrosohydrazino)-ethanamine (NOC-12) to the mouse pontine reticular formation also caused a concentration-dependent increase in ACh release (P < 0.001). These are the first neurochemical data showing that ACh release in the pontine reticular formation of the B6 mouse is modulated by NO. The signal transduction cascade through which NO modulates ACh release in the pontine reticular formation has not previously been characterized. Therefore, an additional series of studies quantified the effects of a soluble guanylate cyclase (sGC) inhibitor, 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ), on ACh release in the cat medial pontine reticular formation. During naturally occurring states of sleep and wakefulness, but not anesthesia, ODQ caused a significant (P < 0.001) decrease in ACh release. These results show for the first time that NO modulates ACh in the medial pontine reticular formation of the cat via an NO-sensitive sGC signal transduction cascade. Isoflurane and halothane anesthesia have been shown to decrease ACh release in the medial pontine reticular formation. The finding that ODQ did not alter ACh release during isoflurane or halothane anesthesia demonstrates that these anesthetics disrupt the NO-sensitive sGC-cGMP pathway. Considered together, results from the mouse and cat indicate that NO modulates ACh release in arousal-promoting regions of the pontine reticular formation via an NO-sensitive sGC-cGMP pathway.

A new stratigraphic model for the deposition of the Dammam Formation

NASA Astrophysics Data System (ADS)

Lokier, Stephen; Fiorini, Flavia; Min, Jina

2017-04-01

In recent years, mixed siliciclastic-carbonate successions have increasingly become targets for hydrocarbon exploration and production activities. Despite the abundance of these successions throughout the Middle East, there have been very few attempts to employ quantitative techniques to interpret their depositional settings and to develop constrained sequence stratigraphic models for their deposition. This study focuses on the Eocene age Dammam Formation that crops out on the flanks of the Jebel Hafeet anticline south of Al Ain in the United Arab Emirates. The Dammam Formation comprises units alternating between poorly-lithified, easily-weathered, siliciclastic and marly horizons and well-lithified limestones. These units were deposited in a foreland basin that formed in association with the Late Cretaceous obduction of the Semail Ophiolite onto the northeastern margin of the Arabian Plate. The Paleogene infilling of this basin is recorded in the shallowing-upward sedimentary sequence of the lithologies of the Pabdeh Group. This succession records the transition from marine carbonate sedimentation, through increasingly evaporitic-dominated units during the late Eocene to early Miocene to a fluvial-alluvial system by mid to late Miocene times. The Dammam Formation was deposited in an open shallow-marine setting strongly influenced by the influx of siliciclastic material sourced from the close-by uplifted massif of the obducted ophiolite. The skeletal assemblage of the Dammam Formation is dominated by Nummulites and Assilina larger benthic foraminifera along with subordinate smaller foraminifera, echinoids, bivalves, corals, bryozoan, gastropods, echinoids and calcareous algae. Previous studies of the Dammam Formation have employed the biotic component in the reconstruction of water depth. However, these studies neglected to consider that turbidity, associated with the abundant siliciclastic component, resulted in a reduction in the depth of the euphotic zone and a consequent response of the benthic biota. We employ a range of quantitative analytical techniques in order to constrain the influence of the siliciclastic component on the lithofacies of the Dammam Formation and present a new sequence stratigraphic model for the deposition of the formation.

Revision of the biostratigraphy of the Chatham Group (Upper Triassic), Deep River basin, North Carolina, USA

USGS Publications Warehouse

Litwin, R.J.; Ash, S.R.

1993-01-01

Paleontological evidence from the Upper Triassic Chatham Group in the three subbasins of the Deep River basin (North Carolina, USA) supports a significant revision of the ages assigned to most of this non-marine continental sedimentary sequence. This study confirms an early(?) or mid-Carnian age in the Sanford subbasin for the base of the Pekin Formation, the lowest unit of the Chatham Group. However, diagnostic late Carnian palynomorphs have been recovered from coals in the lower part of the Cumnock Formation in the Sanford subbasin, and from a sample of the Cumnock Formation equivalent in the Wadesboro subbasin. Plant megafossils and fossil verebrates from rocks in the Sanford subbasin also support a late Carnian age for the Cumnock Formation and its equivalents. The overlying Sanford Formation, which has not yet been dated paleontologically, probably includes beds of Norian age, as over 1000 m of strata may be present between the Cumnock Formation coals (dated here as late Carnian) and the top of the Sanford Formation. This chronostratigraphic interval appears similar to, but slightly longer than, that preserved in the Dan River-Danville and Davie County basins 100 km to the northwest. Our evidence, therefore, indicates that the Chatham Group was deposited over a much longer time interval [early(?) to mid-Carnian through early Norian] than previously was believed. ?? 1993.