bluuebunny/crossref_metadata_2025_split huggingface dataset:
Degradation Analysis of the SnO2 and ZnO‐Based Varistors Using Electrostatic Force Microscopy
Authors: Ramírez M. A. , Tararam R. , Simões A.Z. , Ries A. , Longo E. , Varela J. A. 
Published: March 2013

The degradation phenomena of ZnO and SnO2‐based varistors were investigated for two different degradation methods: DC voltage at increased temperature and degradation with 8/20 μs pulsed currents (lightning type). Electrostatic force microscopy (EFM) was used to analyze the surface charge accumulated at grain‐boundary regions before and after degradation. Before the degradation process, 85% of the barriers are active in the SnO2 system, while the ZnO system presents only 30% effective barriers. Both systems showed changes in the electrical behavior when degraded with pulses. In the case of the ZnO system, the behavior after pulse degradation was essentially ohmic due to the destruction of barriers (about 99% of the interfaces are conductive). After the degradation with 8/20 μs pulsed currents, the SnO2 system still presents nonohmic behavior with a significant decrease in the quantity of effective barriers (from 85% to 5%). However, when the degradation is accomplished with continuous current, the SnO2 system exhibits minimum variation, while the ZnO system degrades from 30% to 5%. This result indicates the existence of metastable defects of low concentration and/or low diffusion in the SnO2 system. High energy is necessary to degrade the barriers due to defect annihilation in the SnO2 system.
Escherichia coli Concentrations in Urban Watersheds Exhibit Diurnal Sag: Implications for Water‐Quality Monitoring and Assessment
Authors: Desai Anuradha M. , Rifai Hanadi S. 
Published: March 2013

AbstractThe variability of indicator bacteria over a fine resolution time scale on the order of minutes has yet to be fully understood. In this study, we collected more than 700 Escherichia coli samples at a 10‐ and 30‐min resolution in an urban watershed in Houston. A Bacteria Diurnal Sag (BDS) marked with daytime exponential decay followed by an exponential nighttime regeneration was observed. This pattern was observed during all sampled events but varied depending on other variables. The concentrations during a 24‐h period varied 1 to 5 orders of magnitude and the fecal load was at least 10 times lower than what would be obtained using a single morning E. coli measurement, the typical sampling scheme in most monitoring programs. Decay rates, ranging from 3.67 to 24.7/day, decreased E. coli concentrations to below the water‐quality standards from 14:00 to 18:00 h and were strongly influenced by water temperatures and solar radiation intensities. Rapid regeneration occurred on the order of 9.41 to 64.1/day allowing E. coli concentrations to return to their pre‐decay levels. The data indicated that four to six samples taken between 06:00 and 18:00 h may be sufficient to define the BDS depending on stream conditions, and that a threshold concentration of approximately 100 MPN/dl (most probable number in a deciliter) existed for the studied urban watershed. These findings have significant implications for water‐quality monitoring, regulation, and compliance.
Historical biogeography and ecological opportunity in the adaptive radiation of native Hawaiian leafhoppers (Cicadellidae: Nesophrosyne)
Authors: Bennett Gordon M. , O'Grady Patrick M. 
Published: March 2013

AbstractAimOur aims were to infer the roles of ecology and geology in the adaptive radiation, historical biogeography, and diversification dynamics of the native Hawaiian leafhoppers (Hemiptera: Cicadellidae: Nesophrosyne).LocationThe Hawaiian Archipelago.MethodsA six gene molecular data set for 191 Nesophrosyne species was used to reconstruct relationships in absolute time with relaxed Bayesian methods. Dated phylogenetic hypotheses were used to reconstruct historical biogeography and host plant associations. Phylogenetic clustering methods were implemented to examine the structuring of Nesophrosyne species according to island. Lineage diversification dynamics were inferred using the γ‐statistic and birth–death likelihood methods.ResultsNesophrosyne split from a common ancestor with its sister genus 4.5 million years ago (Ma), with a basal divergence in Hawaii 3.2 Ma. Historical biogeographical reconstructions reveal a Kauai origin for the genus and complex island colonization patterns. Ancestral host plant associations reconstruct Urticaceae and Rubiaceae at the root, with host transitions resulting in host‐specific clades. Only species endemic to Kauai are significantly clustered with respect to the whole phylogeny; however, species show significant terminal level clustering for the four main high islands. Diversification rates in Nesophrosyne show an initial burst in net speciation rate with a subsequent decline.Main conclusionsNesophrosyne colonized the Hawaiian Islands after the formation of Kauai. Host plant arrival times and insect–insect competition may have been important in shaping diversification patterns. The plant families Urticaceae and Rubiaceae played critical roles in the early diversification of Nesophrosyne. Island geography imposed significant barriers to gene flow, leading to extensive allopatric speciation and intra‐island diversification. A high initial net speciation rate was associated with host plant transitions, and the formation and establishment of Nesophrosyne on multi‐volcano islands (e.g. Oahu and Maui Nui). Net diversification rates exhibit a diversity‐dependent decline, corresponding to the end phase of island formation.
Infections in Long‐Term Care Populations in the United States
Authors: Dwyer Lisa L. , Harris‐Kojetin Lauren D. , Valverde Roberto H. , Frazier Joyce M. , Simon Alan E. , Stone Nimalie D. , Thompson Nicola D. 
Published: March 2013

ObjectivesTo estimate infection prevalence and explore associated risk factors in nursing home (NH) residents, individuals receiving home health care (HHC), and individuals receiving hospice care.DesignCross‐sectional.SettingNationally representative samples of 1,174 U.S. NHs in the 2004 National Nursing Home Survey (NNHS) and 1,036 U.S. HHC and hospice agencies in the 2007 National Home and Hospice Care Survey (NHHCS).ParticipantsA nationally representative sample of 12,270 NH residents, 4,394 individuals receiving HHC, and 4,410 individuals receiving hospice care.MeasurementsInternational Classification of Diseases, Ninth Revision, Clinical Modification, codes were used to identify the presence of infection, including community‐acquired infection and those acquired during earlier healthcare exposures.ResultsUnweighted response rates were 78% for the 2004 NHHS and 67% for the 2007 NHHCS. Approximately 12% of NH residents and 12% of individuals receiving HHC had an infection at the time of the survey interview, and more than 10% of individuals receiving hospice care had an infection when discharged from hospice care. The most common infections were urinary tract infection (3.0–5.2%), pneumonia (2.2–4.4%), and cellulitis (1.6–2.0%). Short length of care and recent inpatient stay in a healthcare facility were associated with infections in all three populations. Taking 10 or more medications and urinary catheter exposure were significant in two of these three long‐term care populations.ConclusionInfection prevalence in HHC, hospice, and NH populations is similar. Although these infections may be community acquired or acquired during earlier healthcare exposures, these findings fill an important gap in understanding the national infection burden and may help inform future research on infection epidemiology and prevention strategies in long‐term care populations.
Regulation of contact inhibition of locomotion by Eph–ephrin signalling
Authors: BATSON J. , ASTIN J.W. , NOBES C.D. 
Published: March 2013

SummaryContact inhibition of locomotion (CIL) occurs when a cell stops migrating in a particular direction upon contact with another cell. Many cancer cells show Contact inhibition of locomotion when contacting one another but display contact‐unimpeded migration following collision with noncancer cells. Here we review current understanding of Contact inhibition of locomotion, from Abercrombie's historical studies of cells in tissue culture to more recent analyses of Contact inhibition of locomotion in vivo. We discuss the cellular machinery required for CIL and the molecular signals that regulate it. We focus on our recent finding that in prostate cancer cells, Contact inhibition of locomotion is regulated by a balance between EphA and EphB receptor signalling. We show that, as recently described for chick heart fibroblasts, microtubule dynamics are required for Contact inhibition of locomotion in prostate cancer cells and we propose that stabilization of microtubules could account for defective Contact inhibition of locomotion between cancer cells and noncancer cells.
Qualitative microanalysis of calcium local structure in tooth layers by means of micro‐RRS
Authors: LEANI J.J. , SÁNCHEZ H.J. , VALENTINUZZI M.C. , PÉREZ C. , GRENÓN M.C. 
Published: March 2013

SummaryThe Resonant inelastic X‐ray scattering or resonant Raman scattering is an inelastic process of second order that becomes important when the energy of the excitation radiation is below but close to an absorption edge. In this process, the emitted photons have a continuous energy distribution with a high energy cut‐off limit. In the last few years, experiments of resonant Raman scattering has become a very powerful technique to investigate excitations of electrons in solids. A qualitative study of the calcium local structure in the different layers of teeth was carried out. In order to perform the analysis, several measurements of tooth samples were achieved using monochromatic synchrotron radiation at the XRF station of the D09B‐XRF beamline at the Brazilian synchrotron facility (LNLS, Campinas), below and close to the K absorption edge of Ca to inspect the resonant Raman scattering spectra. First of all, the spectra were analyzed with specific software to fit the experimental data. After that, the residuals were determined and a  fast Fourier transform smoothing procedure was applied, taking into account the instrument functions of the detecting system. These oscillations present patterns that depend of the tooth layer, i.e. of the calcium state.
Hypercoagulability as a contributor to thrombotic complications in the liver transplant recipient
Authors: Arshad Freeha , Lisman Ton , Porte Robert J. 
Published: March 2013

AbstractTraditionally, perioperative bleeding complications were a major concern during orthotopic liver transplantation, but a tremendous decline in transfusion requirements has been reported over the last decade. In recent years, there has been an increasing awareness towards perioperative thrombotic complications, including liver vessel thrombosis, and systemic venous and arterial thromboembolic events. Whereas a number of these thrombotic complications were previously categorized as surgical complications, increasing clinical and laboratory evidence suggest a role for the haemostatic system in thrombotic complications occurring during and after transplantation. High levels of the platelet adhesive protein von Willebrand factor with low levels of its regulator ADAMTS13, an increased potential to generate thrombin, and temporary hypofibrinolysis are all indicative of increased haemostatic potential after transplantation. Clinical evidence for a role of the haemostatic system in post‐operative thromboses includes a higher thrombotic risk in patients with various acquired thrombotic risk factors. Although data on efficacy of anticoagulant therapy after liver transplantation are scarce, one study has shown a significant decrease in the risk for late hepatic artery thrombosis by antithrombotic therapy with aspirin. These findings suggest that antihaemostatic therapy in prevention or treatment of thromboembolic complications after liver transplantation may be relevant. Studies on efficacy and safety of these interventions are required as many of the thrombotic complications have a pronounced negative impact on graft and patient survival.
Lithium isotopes as indicators of meteorite parent body alteration
Authors: Sephton Mark A. , James Rachael H. , Fehr Manuela A. , Bland Philip A. , Gounelle Matthieu 
Published: March 2013

AbstractHydrothermal processing on planetesimals in the early solar system produced new mineral phases, including those generated by the transformation of anhydrous silicates into their hydrated counterparts. Carbonaceous chondrites represent tangible remnants of such alteration products. Lithium isotopes are known to be responsive to aqueous alteration, yet previously recognized variability within whole rock samples from the same meteorite appears to complicate the use of these isotopes as indicators of processing by water. We demonstrate a new way to use lithium isotopes that reflects aqueous alteration in carbonaceous chondrites. Temperature appears to exert a control on the production of acetic acid‐soluble phases, such as carbonates and poorly crystalline Fe‐oxyhydroxides. Temperature and degree of water‐rock interaction determines the amount of lithium isotope fractionation expressed as the difference between whole rock and acetic acid‐leachable fractions. Using these features, the type 1 chondrite Orgueil (δ7Li(whole rock) = 4.3‰; Δ7Li(acetic‐whole) = 1.2‰) can be distinguished from the type 2 chondrites Murchison (δ7Li(whole rock) = 3.8; Δ7Li(acetic‐whole) = 8.8‰) and carbonate‐poor Tagish Lake (δ7Li(whole rock) = 4.3; Δ7Li(acetic‐whole) = 9.4‰). This initial study suggests that lithium isotopes have the potential to reveal the role of liquid water in the early solar system.
Congruence between distribution modelling and phylogeographical analyses reveals Quaternary survival of a toadflax species (Linaria elegans) in oceanic climate areas of a mountain ring range
Authors: Fernández‐Mazuecos Mario , Vargas Pablo 
Published: March 2013

Summary

The role of Quaternary climatic shifts in shaping the distribution of Linaria elegans, an Iberian annual plant, was investigated using species distribution modelling and molecular phylogeographical analyses. Three hypotheses are proposed to explain the Quaternary history of its mountain ring range.

The distribution of L. elegans was modelled using the maximum entropy method and projected to the last interglacial and to the last glacial maximum (LGM) using two different paleoclimatic models: the Community Climate System Model (CCSM) and the Model for Interdisciplinary Research on Climate (MIROC). Two nuclear and three plastid DNA regions were sequenced for 24 populations (119 individuals sampled). Bayesian phylogenetic, phylogeographical, dating and coalescent‐based population genetic analyses were conducted.

Molecular analyses indicated the existence of northern and southern glacial refugia and supported two routes of post‐glacial recolonization. These results were consistent with the LGM distribution as inferred under the CCSM paleoclimatic model (but not under the MIROC model). Isolation between two major refugia was dated back to the Riss or Mindel glaciations, > 100 kyr before present (bp).

The Atlantic distribution of inferred refugia suggests that the oceanic (buffered)–continental (harsh) gradient may have played a key and previously unrecognized role in determining Quaternary distribution shifts of Mediterranean plants.
Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization
Authors: Segars W. P. , Bond Jason , Frush Jack , Hon Sylvia , Eckersley Chris , Williams Cameron H. , Feng Jianqiao , Tward Daniel J. , Ratnanather J. T. , Miller M. I. , Frush D. , Samei E. 
Published: March 2013

Purpose:The authors previously developed the 4D extended cardiac‐torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole‐body models for the standard male and female adult, including the cardiac and respiratory motions. In this work, the authors extend the XCAT beyond these reference anatomies by developing a series of anatomically variable 4D XCAT adult phantoms for imaging research, the first library of 4D computational phantoms.Methods:The initial anatomy of each phantom was based on chest–abdomen–pelvis computed tomography data from normal patients obtained from the Duke University database. The major organs and structures for each phantom were segmented from the corresponding data and defined using nonuniform rational B‐spline surfaces. To complete the body, the authors manually added on the head, arms, and legs using the original XCAT adult male and female anatomies. The structures were scaled to best match the age and anatomy of the patient. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from the template XCAT phantom (male or female) to the target patient model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. Each new phantom was refined by checking for anatomical accuracy via inspection of the models.Results:Using these methods, the authors created a series of computerized phantoms with thousands of anatomical structures and modeling cardiac and respiratory motions. The database consists of 58 (35 male and 23 female) anatomically variable phantoms in total. Like the original XCAT, these phantoms can be combined with existing simulation packages to simulate realistic imaging data. Each new phantom contains parameterized models for the anatomy and the cardiac and respiratory motions and can, therefore, serve as a jumping point from which to create an unlimited number of 3D and 4D variations for imaging research.Conclusions:A population of phantoms that includes a range of anatomical variations representative of the public at large is needed to more closely mimic a clinical study or trial. The series of anatomically variable phantoms developed in this work provide a valuable resource for investigating 3D and 4D imaging devices and the effects of anatomy and motion in imaging. Combined with Monte Carlo simulation programs, the phantoms also provide a valuable tool to investigate patient‐specific dose and image quality, and optimization for adults undergoing imaging procedures.
Objected constrained registration and manifold learning: A new patient setup approach in image guided radiation therapy of thoracic cancer
Authors: Chen Ting , Jabbour Salma K. , Qin Songbing , Haffty Bruce G. , Yue Ning 
Published: March 2013

Purpose:The management of thoracic malignancies with radiation therapy is complicated by continuous target motion. In this study, a real time motion analysis approach is proposed to improve the accuracy of patient setup.Methods:For 11 lung cancer patients a long training fluoroscopy was acquired before the first treatment, and multiple short testing fluoroscopies were acquired weekly at the pretreatment patient setup of image guided radiotherapy (IGRT). The data analysis consisted of three steps: first a 4D target motion model was constructed from 4DCT and projected to the training fluoroscopy through deformable registration. Then the manifold learning method was used to construct a 2D subspace based on the target motion (kinetic) and location (static) information in the training fluoroscopy. Thereafter the respiratory phase in the testing fluoroscopy was determined by finding its location in the subspace. Finally, the phase determined testing fluoroscopy was registered to the corresponding 4DCT to derive the pretreatment patient position adjustment for the IGRT. The method was tested on clinical image sets and numerical phantoms.Results:The registration successfully reconstructed the 4D motion model with over 98% volume similarity in 4DCT, and over 95% area similarity in the training fluoroscopy. The machine learning method derived the phase values in over 98% and 93% test images of the phantom and patient images, respectively, with less than 3% phase error. The setup approach achieved an average accumulated setup error less than 1.7 mm in the cranial‐caudal direction and less than 1 mm in the transverse plane. All results were validated against the ground truth of manual delineations by an experienced radiation oncologist. The expected total time for the pretreatment setup analysis was less than 10 s.Conclusions:By combining the registration and machine learning, the proposed approach has the potential to improve the accuracy of pretreatment setup for patients with thoracic malignancy.
Role of the Phenylalanine-Hydroxylating System in Aromatic Substance Degradation and Lipid Metabolism in the Oleaginous Fungus Mortierella alpina
Authors: Wang Hongchao , Chen Haiqin , Hao Guangfei , Yang Bo , Feng Yun , Wang Yu , Feng Lu , Zhao Jianxin , Song Yuanda , Zhang Hao , Chen Yong Q. , Wang Lei , Chen Wei 
Published: March 2013

ABSTRACT

Mortierella alpina
is a filamentous fungus commonly found in soil that is able to produce lipids in the form of triacylglycerols that account for up to 50% of its dry weight. Analysis of the
M. alpina
genome suggests that there is a phenylalanine-hydroxylating system for the catabolism of phenylalanine, which has never been found in fungi before. We characterized the phenylalanine-hydroxylating system in
M. alpina
to explore its role in phenylalanine metabolism and its relationship to lipid biosynthesis. Significant changes were found in the profile of fatty acids in
M. alpina
grown on medium containing an inhibitor of the phenylalanine-hydroxylating system compared to
M. alpina
grown on medium without inhibitor. Genes encoding enzymes involved in the phenylalanine-hydroxylating system (phenylalanine hydroxylase [PAH], pterin-4α-carbinolamine dehydratase, and dihydropteridine reductase) were expressed heterologously in
Escherichia coli
, and the resulting proteins were purified to homogeneity. Their enzymatic activity was investigated by high-performance liquid chromatography (HPLC) or visible (Vis)-UV spectroscopy. Two functional PAH enzymes were observed, encoded by distinct gene copies. A novel role for tetrahydrobiopterin in fungi as a cofactor for PAH, which is similar to its function in higher life forms, is suggested. This study establishes a novel scheme for the fungal degradation of an aromatic substance (phenylalanine) and suggests that the phenylalanine-hydroxylating system is functionally significant in lipid metabolism.
Carbohydrate-Binding Module–Cyclodextrin Glycosyltransferase Fusion Enables Efficient Synthesis of 2-
O
-
d
-Glucopyranosyl-
l
-Ascorbic Acid with Soluble Starch as the Glycosyl Donor
Authors: Han Ruizhi , Li Jianghua , Shin Hyun-Dong , Chen Rachel R. , Du Guocheng , Liu Long , Chen Jian 
Published: March 2013

ABSTRACT

In this study, we achieved the efficient synthesis of 2-
O
-
d
-glucopyranosyl-
l
-ascorbic acid (AA-2G) from soluble starch by fusing a carbohydrate-binding module (CBM) from
Alkalimonas amylolytica
α-amylase (CBM
Amy
) to cyclodextrin glycosyltransferase (CGTase) from
Paenibacillus macerans
. One fusion enzyme, CGT-CBM
Amy
, was constructed by fusing the CBM
Amy
to the C-terminal region of CGTase, and the other fusion enzyme, CGTΔE-CBM
Amy
, was obtained by replacing the E domain of CGTase with CBM
Amy
. The two fusion enzymes were then used to synthesize AA-2G from soluble starch as a cheap and easily soluble glycosyl donor. Under the optimal conditions, the AA-2G yields produced using CGTΔE-CBM
Amy
and CGT-CBM
Amy
were 2.01 g/liter and 3.03 g/liter, respectively, which were 3.94- and 5.94-fold of the yield from the wild-type CGTase (0.51 g/liter). The reaction kinetics of the two fusion enzymes were analyzed and modeled to confirm the enhanced specificity toward soluble starch. It was also found that, compared to the wild-type CGTase, the two fusion enzymes had relatively high hydrolysis and disproportionation activities, factors that favor AA-2G synthesis. Finally, it was speculated that the enhancement of soluble starch specificity may be related to the changes of substrate binding ability and the substrate binding sites between the CBM and the starch granule.