bluuebunny/crossref_metadata_2025 huggingface dataset:
A METAPOPULATION MODEL WITH DISCRETE SIZE STRUCTURE
Authors: MARTCHEVA MAIA , THIEME HORST R.
Published: August 2010

ABSTRACT. We consider a discrete size‐structured meta‐population model with the proportions of patches occupied by n individuals as dependent variables. Adults are territorial and stay on a certain patch. The juveniles may emigrate to enter a dispersers' pool from which they can settle on another patch and become adults. Absence of colonization and absence of emigration lead to extinction of the metapopula‐tion. We define the basic reproduction number R0 of the metapopulation as a measure for its strength of persistence. The metapopulation is uniformly weakly persistent if R0> 1. We identify subcritical bifurcation of persistence equilibria from the extinction equilibrium as a source of multiple persistence equilibria: it occurs, e.g., when the immigration rate, into occupied patches, exceeds the colonization rate (of empty patches). We determine that the persistence‐optimal dispersal strategy which maximizes the basic reproduction number is of bang‐bang type: If the number of adults on a patch is below carrying capacity all the juveniles should stay, if it is above the carrying capacity all the juveniles should leave.
HABITAT PATCH OCCUPANCY DYNAMICS OF GLAUCOUS‐WINGED GULLS (LARUS GLAUCESCENS) I: A DISCRETE‐TIME MODEL
Authors: PHILLIPS KARL W. , DAMANIA SMRUTI P. , HAYWARD JAMES L. , HENSON SHANDELLE M. , LOGAN CLARA J.
Published: August 2010

ABSTRACT. Diurnal habitat occupancy dynamics of Glaucous‐winged Gulls were evaluated in a system of six habitats on and around Protection Island, Washington. Data were collected on the rates of gull movement between habitat patches, and from these data the probabilities of transitions between habitats were estimated as functions of tide height and time of day. A discrete‐time matrix model based on the transition probabilities was used to generate habitat occupancy predictions, which were then compared to hourly census data. All model parameters were estimated directly from data rather than through model fitting. The model made reasonable predictions for two of the six habitats and explained 45% of the variability in the data from 2003. The construction and testing of mathematical models that predict occupancies in multiple habitats may play increasingly important roles in the understanding and management of animal populations within complex environments.
USING NETWORK ANALYSIS TO CHARACTERIZE FOREST STRUCTURE
Authors: FULLER MICHAEL M. , WAGNER ANDREAS , ENQUIST BRIAN J.
Published: August 2010

Abstract Network analysis quantifies different structural properties of systems of interrelated parts using a single analytical framework. Many ecological phenomena have network‐like properties, such as the trophic relationships of food webs, geographic structure of metapopulations, and species interactions in communities. Therefore, our ability to understand and manage such systems may benefit from the use of network‐analysis techniques. But network analysis has not been applied extensively to ecological problems, and its suitability for ecological studies is uncertain. Here, we investigate the ability of network analysis to detect spatial patterns of species association in a tropical forest. We use three common graph‐theoretic measures of network structure to quantify the effect of understory tree size on the spatial association of understory species with trees in the canopy: the node degree distribution (NDD), characteristic path length (CPL), and clustering coefficient (CC). We compute the NDD, CPL, and CC for each of seven size classes of understory trees. For significance testing, we compare the observed values to frequency distributions of each statistic computed from randomized data. We find that the ability of network analysis to distinguish observed patterns from those representing randomized data strongly depends on which aspects of structure are investigated. Analysis of NDD finds no significant difference between random and observed networks. However, analysis of CPL and CC detected nonrandom patterns in three and one of the seven size classes, respectively. Network analysis is a very flexible approach that holds promise for ecological studies, but more research is needed to better understand its advantages and limitations.
A STATE‐SPACE MODEL FOR UNIVARIATE ORDINAL‐VALUED TIME SERIES
Authors: RIZZARDI MARK
Published: August 2010

AbstractA state‐space model was developed to analyze a univariate time series of ordinal‐valued flower phenology data. Flower abundance, recorded as either “none,”“some,” or “much,” was observed each month on trees in a lowland Costa Rican rain forest to investigate flowering patterns of different species. Data from a singleCapparis pittieriand daily rain measurements are used to demonstrate the model. A method to obtain maximum likelihood estimates of the parameters and the use of predicted probability differences to assess goodness of fit are described. Opportunities for improving the model are also discussed.
COALITIONS IN INTERNATIONAL FISHERIES MANAGEMENT
Authors: LINDROOS MARKO
Published: August 2010

Abstract We show that with symmetric agents, noncooperation is the only stable coalition structure in a fishery with more than two countries. In the case of asymmetric fishing nations, partial or full cooperation may be stable even if the number of countries exceeds two. These are important results for recent fisheries economics papers that have not allowed for coalition formation. As an example how of one can use the model, we study the problem of new entrants into Regional Fisheries Management Organizations (RFMOs). We show that depending on the economic structure of the fishery, new entrants may make cooperation more difficult or easier.
Analysis of Heat Transfer Factors for a Heat Pipe Absorber Array Connected to a Common Manifold
Authors: Hull J. R.
Published: August 2010

Heat transfer factors and thermal efficiency are calculated for a heat pipe absorber array connected to a common manifold. Arrays with less than ten heat pipes are shown to have significantly less efficiency than a conventional flow-through collector. Efficiency is also sensitive to the heat transfer rate per unit temperature difference from the heat pipe fluid to the manifold fluid divided by that from the heat pipe surface to the ambient, with maximum efficiency occurring for ratios greater than 100.
A Computer Analysis of Wind Turbine Blade Dynamic Loads
Authors: Thresher R. W. , Wright A. D. , Hershberg E. L.
Published: August 2010

The flapping motion of a single wind turbine rotor blade has been analyzed and equations describing the flapping motion have been developed. The analysis was constrained to allow only flapping motions for a cantilevered blade, and the equations of motion are linearized. A computer code, called FLAP (Force and Loads Analysis Program), to solve the equations of motion and compute the blade loads, has been completed and compared to measured loads for a 3-bladed downwind turbine with stiff blades. The results of the program are presented in tabulated form for equidistant points along the blade and equal azimuth angles around the rotor disk. The blade deflection, slope and velocity, flapwise shear and moment, edgewise shear and moment, blade tension, and blade torsion are given. The deterministic excitations considered in the analysis include wind shear, tower shadow, gravity, and a prescribed yaw motion.
Speed, accuracy, and confidence in Google, Ovid, PubMed, and UpToDate: results of a randomised trial
Authors: Thiele Robert H , Poiro Nathan C , Scalzo David C , Nemergut Edward C
Published: August 2010

Background

The explosion of biomedical information has led to an ‘information paradox’—the volume of biomedical information available has made it increasingly difficult to find relevant information when needed. It is thus increasingly critical for physicians to acquire a working knowledge of biomedical informatics.

Aim

To evaluate four search tools commonly used to answer clinical questions, in terms of accuracy, speed, and user confidence.

Methods

From December 2008 to June 2009, medical students, resident physicians, and attending physicians at the authors' institution were asked to answer a set of four anaesthesia and/or critical care based clinical questions, within 5 min, using Google, Ovid, PubMed, or UpToDate (only one search tool per question). At the end of each search, participants rated their results on a four point confidence scale. One to 3 weeks after answering the initial four questions, users were randomised to one of the four search tools, and asked to answer eight questions, four of which were repeated. The primary outcome was defined as a correct answer with the highest level of confidence.

Results

Google was the most popular search tool. Users of Google and UpToDate were more likely than users of PubMed to answer questions correctly. Subjects had the most confidence in UpToDate. Searches with Google and UpToDate were faster than searches with PubMed or Ovid.

Conclusion

Non-Medline based search tools are not inferior to Medline based search tools for purposes of answering evidence based anaesthesia and critical care questions.
ANY l-STATE SOLUTIONS OF THE WOODS–SAXON POTENTIAL IN ARBITRARY DIMENSIONS WITHIN THE NEW IMPROVED QUANTIZATION RULE
Authors: IKHDAIR SAMEER M. , SEVER RAMAZAN
Published: August 2010

The approximated energy eigenvalues and the corresponding eigenfunctions of the spherical Woods–Saxon effective potential in D dimensions are obtained within the new improved quantization rule for all l-states. The Pekeris approximation is used to deal with the centrifugal term in the effective Woods–Saxon potential. The interdimensional degeneracies for various orbital quantum number l and dimensional space D are studied. The solutions for the Hulthén potential, the three-dimensional (D = 3), the s-wave (l = 0) and the cases are briefly discussed.
GAUGE FIXING IDENTITY IN THE BACKGROUND FIELD METHOD OF QCD IN PURE GAUGE
Authors: NAYAK GOURANGA C.
Published: August 2010

In this paper we derive a gauge fixing identity by varying the covariant gauge fixing term in [Formula: see text] in the background field method of QCD in pure gauge. Using this gauge fixing identity, we establish a relation between [Formula: see text] in QCD and [Formula: see text] in background field method of QCD in pure gauge. We show the validity of this gauge fixing identity, in general noncovariant and general Coulomb gauge fixings respectively. This gauge fixing identity is used to prove factorization theorem in QCD at high energy colliders and in nonequilibrium QCD at high energy heavy-ion colliders.
ENERGY ESTIMATION OF ULTRA-HIGH ENERGY COSMIC RAY PHOTONS BY MONTE CARLO SIMULATIONS OF EXTENSIVE AIR SHOWERS
Authors: GERANIOS A. , KOUTSOKOSTA D. , MALANDRAKI O. , ROSAKI-MAVROULI H.
Published: August 2010

Ultra-High Energy Cosmic Rays (UHECR) (E ≥ 5 × 1019 eV ) are detected through Extensive Air Showers that are created when a primary cosmic ray particle interacts with the atmosphere of the Earth. The energy of the primary particle can be estimated experimentally based on simulations. In this paper, we attempt to estimate the energy of UHECR gamma ray photons by applying a Monte Carlo simulation code and we compare the results with the ones derived in our previous papers for hadron initiated showers. The scenario of simulations is adapted to the P. Auger Observatory site.
A REFINED BCS APPROACH TO THE DOPING DEPENDENCE OF Tc IN HIGH-Tc SUPERCONDUCTORS
Authors: MAĆKOWIAK JAN , BORYCKI DAWID
Published: August 2010

The presence of dopant ions in a high-temperature superconductor (HTSC) is accounted for by introducing an effective temperature [Formula: see text] of current carriers. It is shown that the BCS formalism, with a power law for the bandwidth and state density dependence on dopant concentration x and a [Formula: see text] temperature scale, yields a closed formula for T c (x), which, in several cases, agrees well with experimental data on T c (x) of HTSCs.
EFFECT OF MINOR Al ADDITION ON GLASS-FORMING ABILITY AND THERMAL STABILITY OF Zr–Cu BINARY ALLOY
Authors: YU Z. H. , DING D. , LU T. , XIA L. , DONG Y. D.
Published: August 2010

By adding 2 at.% Al element in Zr 50 Cu 50 binary glass-forming alloy, we obtained Zr 50 Cu 48 Al 2 glassy rods with diameter larger than 3 mm. The reduced glass transition temperature, parameter γ and the critical section thickness obtained from the differential scanning calorimetry (DSC) traces indicate the better glass-forming ability (GFA) of Zr 50 Cu 48 Al 2 bulk metallic glass (BMG). The super-cooled liquid region and the continuous heating transformation diagram constructed from Vogel–Fulcher–Tammann fitting of crystallization temperature illustrate the enhanced thermal stability of the Zr 50 Cu 48 Al 2 BMG. The mechanism of effect of minor Al addition on GFA was investigated in more detail from Angell's fragility concept and from the thermodynamic point of view respectively.
PROBABILISTIC DESIGN OF AXIALLY COMPRESSED COMPOSITE CYLINDERS WITH GEOMETRIC AND LOADING IMPERFECTIONS
Authors: KRIEGESMANN BENEDIKT , ROLFES RAIMUND , HÜHNE CHRISTIAN , TEßMER JAN , ARBOCZ JOHANN
Published: August 2010

The discrepancy between the analytically determined buckling load of perfect cylindrical shells and experimental test results is traced back to imperfections. The most frequently used guideline for design of cylindrical shells, NASA SP-8007, proposes a deterministic calculation of a knockdown factor with respect to the ratio of radius and wall thickness, which turned out to be very conservative in numerous cases and which is not intended for composite shells. In order to determine a lower bound for the buckling load of an arbitrary type of shell, probabilistic design methods have been developed. Measured imperfection patterns are described using double Fourier series, whereas the Fourier coefficients characterize the scattering of geometry. In this paper, probabilistic analyses of buckling loads are performed regarding Fourier coefficients as random variables. A nonlinear finite element model is used to determine buckling loads, and Monte Carlo simulations are executed. The probabilistic approach is used for a set of six similarly manufactured composite shells. The results indicate that not only geometric but also nontraditional imperfections like loading imperfections have to be considered for obtaining a reliable lower limit of the buckling load. Finally, further Monte Carlo simulations are executed including traditional as well as loading imperfections, and lower bounds of buckling loads are obtained, which are less conservative than NASA SP-8007.
POSTBUCKLING DEGRADATION FE ANALYSIS OF STIFFENED COMPOSITE PANELS
Authors: ARAICO J. ANSÓTEGUI , DE ZARATE ALBERDI I. ORTIZ , ARRIBAS F. REBOLLO
Published: August 2010

The capability of a commercial industrial tool, ABAQUS, to simulate the critical damage mechanisms in stiffened composite panels has been evaluated. The analysis and conclusions are supported by experimental results. The focus is on skin–stringer separation during compressive loading. Results show that the advanced degradation modeling capabilities present in commercial codes today may lead to an accurate characterization of the deep postbuckling range behavior and the collapse of stiffened composite panels. Compared to current design practice, where the first indication of ply failure or the onset of damage propagation is taken as the failure load, the methods used here provide a way to exploit the reserves in composite structures. It is concluded that implementing degradation mechanisms (composite ply and adhesive interface degradation) presents a significant improvement to simulate accurately the deep postbuckling states and collapse for stiffened composite panels with adhesively bonded stringers. The nature of the final loss of load-carrying capacity for this type of structures, by composite ply and adhesive interface failure, driven by postbuckling deformation, makes this simulation approach essential.
AN ANALYSIS TOOL FOR DESIGN AND CERTIFICATION OF POSTBUCKLING COMPOSITE AEROSPACE STRUCTURES
Authors: ORIFICI ADRIAN C. , THOMSON RODNEY S. , DEGENHARDT RICHARD , BISAGNI CHIARA , BAYANDOR JAVID
Published: August 2010

In aerospace, carbon-fiber-reinforced polymer (CFRP) composites and postbuckling skin-stiffened structures are key technologies that have been used to improve structural efficiency. However, the application of composite postbuckling structures in aircraft has been limited due to concerns related to both the durability of composite structures and the accuracy of design tools. In this work, a finite element analysis tool for design and certification of aerospace structures is presented, which predicts collapse by taking the critical damage mechanisms into account. The tool incorporates a global–local analysis technique for predicting interlaminar damage initiation, and degradation models to capture the growth of a pre-existing interlaminar damage region, such as a delamination or skin–stiffener debond, and in-plane ply damage mechanisms such as fiber fracture and matrix cracking. The analysis tool has been applied to single- and multistiffener fuselage-representative composite panels, in both intact and predamaged configurations. This has been performed in a design context, in which panel configurations are selected based on their suitability for experimental testing, and in an analysis context for comparison with experimental results as being representative of aircraft certification studies. For all cases, the tool was capable of accurately capturing the key damage mechanisms contributing to final structural collapse, and suitable for the design of next-generation composite aerospace structures.
NUMERICAL SIMULATION AND TESTING OF A COMPOSITE-STIFFENED STRUCTURE UNDER COMBINED BUCKLING LOADS
Authors: KARACHALIOS E. , VRETTOS C. , MARIOLI-RIGA Z. , BISAGNI C. , CORDISCO P. , DE ZARATE I. ORTIZ , CARUSO A.
Published: August 2010

Prediction of the buckling behavior of structures is of great interest in the aerospace industry, and extensive research is taking place worldwide in that area. The current work concerns numerical simulation of the collapse test of a closed stiffened composite box subjected to compression followed by torsion. Numerical simulation is performed and the results are correlated with experimental findings. The objective is to validate the numerical model and detect any deficiencies of the modeling procedure. For this purpose, a series of quantities numerically predicted are directly compared with experimental ones: strains, displacements, deformation plots and load–displacement curves. The physical test article also contains artificial stringer–skin debondings realized via Teflon film inserts. The energy release rates are calculated at the debonding front using the virtual crack closure technique. The FE model is slightly stiffer than the actual structure but the numerical results are at a reasonable level of agreement with the experimental data.
ECSS HANDBOOK BUCKLING OF STRUCTURES
Authors: CALVI A.
Published: August 2010

The objective of ECSS E-HB-32-24, the handbook titled Buckling of Structures, is to merge the information necessary for proper evaluation of buckling loads, including the robustness of this evaluation and the related margins, both for structures and for structural elements of space systems. An outline of the handbook, with a synopsis of each section, is presented herein. The so-called "Public Review" of the handbook is presently foreseen in the second half of 2009, with the aim of raising formal comments from the aerospace community to be later on processed by the E-HB-32-24 Working Group. The Public Review will be conducted via the ECSS Book Shelf, which is the electronic repository for the ECSS nonnormative documentation. The ECSS Book Shelf is a wiki, i.e. a collection of web pages designed to enable anyone who accesses it to contribute or modify content, using a simplified markup language. Comments on the proposed handbook are solicited from the scientific community and industry.
Induction of Endothelial Nitric Oxide Synthase, SIRT1, and Catalase by Statins Inhibits Endothelial Senescence Through the Akt Pathway
Authors: Ota Hidetaka , Eto Masato , Kano Mitsunobu R. , Kahyo Tomoaki , Setou Mitsutoshi , Ogawa Sumito , Iijima Katsuya , Akishita Masahiro , Ouchi Yasuyoshi
Published: August 2010

Objective—

Statins (3-hydroxy-3-methylglutaryl–coenzyme A reductase inhibitors) have pleiotropic vascular protective effects besides cholesterol lowering. Recently, experimental and clinical studies have indicated that senescence of endothelial cells is involved in endothelial dysfunction and atherogenesis. Therefore, the present study was performed to determine whether statins would reduce endothelial senescence and to clarify the molecular mechanisms underlying the antisenescent property of statins.

Methods and Results—

Senescent human umbilical vein endothelial cells were induced by hydrogen peroxide (H
2
O
2
), as judged by senescence-associated β-galactosidase assay and cell morphological appearance. Atorvastatin, pravastatin, and pitavastatin inhibited the oxidative stress induced-endothelial senescence. These statins phosphorylated Akt at Ser473 and subsequently led to increased expression of endothelial nitric oxide synthase (eNOS), SIRT1, and catalase. Treatment with LY294002 or Akt short interfering RNA decreased the eNOS activation, SIRT1 expression, and antisenescent property of atorvastatin. Moreover, in streptozotocin-diabetic mice, administration of pitavastatin increased eNOS, SIRT1, and catalase expression and decreased endothelial senescence, but levels remained unaltered in
Sirt1
knockout mice.

Conclusion—

Our results indicate that treatment with statins inhibits endothelial senescence and that enhancement of SIRT1 plays a critical role in prevention of endothelial senescence through the Akt pathway, a direct target of statins.
An In Vivo Murine Model of Low-Magnitude Oscillatory Wall Shear Stress to Address the Molecular Mechanisms of Mechanotransduction—Brief Report
Authors: Willett Nick J. , Long Robert C. , Maiellaro-Rafferty Kathryn , Sutliff Roy L. , Shafer Richard , Oshinski John N. , Giddens Don P. , Guldberg Robert E. , Taylor W. Robert
Published: August 2010

Objective—

Current understanding of shear-sensitive signaling pathways has primarily been studied in vitro largely because of a lack of adequate in vivo models. Our objective was to develop a simple and well-characterized murine aortic coarctation model to acutely alter the hemodynamic environment in vivo and test the hypothesis that endothelial inflammatory protein expression is acutely upregulated in vivo by low-magnitude oscillatory wall shear stress (WSS).

Methods and Results—

Our model uses the shape memory response of nitinol clips to reproducibly induce an aortic coarctation and allow subsequent focal control over WSS in the aorta. We modeled the corresponding hemodynamic environment using computational fluid dynamics and showed that the coarctation produces low-magnitude oscillatory WSS distal to the clip. To assess the biological significance of this model, we correlated WSS to inflammatory protein expression and fatty streak formation. Vascular cell adhesion molecule-1 expression and fatty streak formation were both found to increase significantly in regions corresponding to acutely induced low-magnitude oscillatory WSS.

Conclusions—

We have developed a novel aortic coarctation model that will be a useful tool for analyzing the in vivo molecular mechanisms of mechanotransduction in various murine models.
Histone Deacetylase 3 Antagonizes Aspirin-Stimulated Endothelial Nitric Oxide Production by Reversing Aspirin-Induced Lysine Acetylation of Endothelial Nitric Oxide Synthase
Authors: Jung Saet-Byel , Kim Cuk-Seong , Naqvi Asma , Yamamori Tohru , Mattagajasingh Ilwola , Hoffman Timothy A. , Cole Marsha P. , Kumar Ajay , DeRicco Jeremy S. , Jeon Byeong-Hwa , Irani Kaikobad
Published: August 2010

Rationale:

Low-dose acetylsalicylic acid (aspirin) is widely used in the treatment and prevention of vascular atherothrombosis. Cardiovascular doses of aspirin also reduce systemic blood pressure and improve endothelium-dependent vasorelaxation in patients with atherosclerosis or risk factors for atherosclerosis. Aspirin can acetylate proteins, other than its pharmacological target cyclooxygenase, at lysine residues. The role of lysine acetylation in mediating the effects of low-dose aspirin on the endothelium is not known.

Objective:

To determine the role of lysine acetylation of endothelial nitric oxide synthase (eNOS) in the regulation of endothelial NO production by low-dose aspirin and to examine whether the lysine deacetylase histone deacetylase (HDAC)3 antagonizes the effect of low-dose aspirin on endothelial NO production by reversing acetylation of functionally critical eNOS lysine residues.

Methods and Results:

Low concentrations of aspirin induce lysine acetylation of eNOS, stimulating eNOS enzymatic activity and endothelial NO production in a cyclooxygenase-1–independent fashion. Low-dose aspirin in vivo also increases bioavailable vascular NO in an eNOS-dependent and cyclooxygenase-1–independent manner. Low-dose aspirin promotes the binding of eNOS to calmodulin. Lysine 609 in the calmodulin autoinhibitory domain of bovine eNOS mediates aspirin-stimulated binding of eNOS to calmodulin and eNOS-derived NO production. HDAC3 inhibits aspirin-stimulated (1) lysine acetylation of eNOS, (2) eNOS enzymatic activity, (3) eNOS-derived NO, and (4) binding of eNOS to calmodulin. Conversely, downregulation of HDAC3 promotes lysine acetylation of eNOS and endothelial NO generation.

Conclusions:

Lysine acetylation of eNOS is a posttranslational protein modification supporting low-dose aspirin-induced vasoprotection. HDAC3, by deacetylating aspirin-acetylated eNOS, antagonizes aspirin-stimulated endothelial production of NO.
Zyxin Mediation of Stretch-Induced Gene Expression in Human Endothelial Cells
Authors: Wójtowicz Agnieszka , Babu Sahana Suresh , Li Li , Gretz Norbert , Hecker Markus , Cattaruzza Marco
Published: August 2010

Rationale:

Prolonged exposure to enhanced stretch, such as in hypertension, triggers endothelial dysfunction, a hallmark of pathological vascular remodeling processes. Despite its clinical relevance, little is known about stretch-induced gene expression in endothelial cells.

Objective:

Here, we have characterized a new stretch-inducible signaling pathway and the subsequent changes in endothelial gene expression in response to stretch.

Methods and Results:

Using human primary endothelial cells, we observed that the protein zyxin translocates from focal adhesions to the nucleus solely in response to stretch. There, it orchestrates complex changes in gene expression by interacting with a novel
cis
-acting element found in all zyxin-regulated genes analyzed so far. By way of DNA microarray pathway analyses, stretch-induced changes in endothelial cell gene expression were systematically explored, revealing that zyxin mainly regulates proinflammatory pathways.

Conclusions:

Stretch appears to be an important factor in the development of endothelial dysfunction with zyxin as a potential therapeutic target to interfere with these early changes in endothelial cell phenotype.
Attitudes and Beliefs of Michigan Emergency Physicians Toward Tissue Plasminogen Activator Use in Stroke
Authors: Scott Phillip A. , Xu Zhenzhen , Meurer William J. , Frederiksen Shirley M. , Haan Mary N. , Westfall Michael W. , Kothari Sandip U. , Morgenstern Lewis B. , Kalbfleisch John D.
Published: August 2010

Background and Purpose—

The objective of this study was to determine the baseline proportion of emergency physicians with favorable attitudes and beliefs toward intravenous tissue plasminogen activator (tPA) use in a cohort of randomly selected Michigan hospitals.

Methods—

Two hundred seventy-eight emergency physicians from 24 hospitals were surveyed. A confidential, self-administered, pilot-tested survey assessing demographics, practice environment, attitudes, and beliefs regarding tPA use in stroke was used. Main outcome measures assessed belief in a legal standard of care, likelihood of use in an ideal setting, comfort in use without a specialist consultation, and belief that science on tPA use is convincing. ORs with robust 95% CIs (adjusted for clustering) were calculated to quantify the association between responses and physician- and hospital-level characteristics.

Results—

One hundred ninety-nine surveys completed (gross response rate 71.6%). Ninety-nine percent (95% CI: 97.8 to 100) indicated use of tPA in eligible patients represented either acceptable or ideal patient care. Twenty-seven percent (95% CI: 21.7 to 32.3) indicated use of tPA represented a legal standard of care. Eighty-three percent (95% CI: 78.5 to 87.5) indicated they were “likely” or “very likely” to use tPA given an ideal setting. When asked about using tPA without a consultation, 65% (95% CI: 59.3 to 70.7) indicated they were uncomfortable. Forty-nine percent (95% CI: 43.0 to 55.0) indicated the science regarding use of tPA in stroke is convincing with 30% remaining neutral. Characteristics associated with favorable attitudes included non-emergency medicine board certification; older age, and a smaller hospital practice environment.

Conclusions—

In this cohort, emergency physician attitudes and beliefs toward intravenous tPA use in stroke are considerably more favorable than previously reported.
Thrombin Mediates Severe Neurovascular Injury During Ischemia
Authors: Chen Bo , Cheng Qun , Yang Kai , Lyden Patrick D.
Published: August 2010

Background and Purpose—

Cerebral ischemia initiates cascades of pathological events such as edema, blood–brain barrier breakdown, and tissue degeneration. Thrombin activation is a key step in coagulation, and thrombin has recently been shown to mediate endothelial permeability and cellular toxicity in vitro. We examined the effect of thrombin on vasculature during ischemia in vivo.

Methods—

Focal ischemia was induced in adult Sprague-Dawley rats by occlusion of the middle cerebral artery for 4 hours followed by a short period of reperfusion. High-molecular-weight fluorescein isothiocyanate-dextran was injected before surgery to label the severe vascular disruption. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining was used to identify dying cells, which were quantified with manual counts. Intra-arterial thrombin or intravenous thrombin inhibitors were infused during ischemia and reperfusion.

Results—

Infusion of thrombin (3 U/kg) intra-arterially during ischemia greatly enlarged the volume of severe vascular disruption, as visualized by fluorescein isothiocyanate–dextran extravasation (
P
<0.05). Thrombin also promoted blood–brain barrier leakage of IgG during ischemia. Vascular disruption was blocked by intravenous infusion of the direct thrombin inhibitor argatroban (1.69 mg/kg,
P
<0.05). Greater numbers of dying cells were found in regions of severe vascular disruption, and interventions that reduced vascular leakage also reduced the numbers of dying cells.

Conclusions—

Thrombin mediates severe vascular disruption during ischemia and thrombin inhibitors may partially ameliorate vascular disruption. Further work is needed to establish whether thrombin, entering parenchyma due to increased vascular permeability, augments neurotoxicity during ischemia.
Extending Citizenship to Emigrants: Democratic Contestation and a New Global Norm
Authors: Rhodes Sybil , Harutyunyan Arus
Published: August 2010

We argue that the growing literature on emigrant policies should be linked to more general theoretical discussions of the expansion of formal citizenship. State responses to emigrants’ claims for membership and voting rights resemble patterns of citizenship extension to other previously excluded groups, such as those without property, racial minorities, and women, insofar as emigrant citizenship has developed as a consequence of competitive regimes and international norms. We assess the ‘global-norm hypothesis’ (the idea that increasing emigrant inclusion has resulted from the emergence of a new international normative standard) and the ‘contestation hypothesis’ (the argument that higher levels of regime competition make states more likely to extend citizenship to emigrants). The latter has two associated expectations: the ‘window-of-opportunity sub-hypothesis’, which holds that regime transitions provide an especially propitious context for implementing emigrant citizenship, and the ‘democratic-endurance sub-hypothesis’, which posits that competitive regimes are likely to extend emigrant citizenship in a gradual process over time. We use a combination of statistical analysis and case studies of Armenia, Mexico, Spain, and the USA to evaluate these causal hypotheses as well as some plausible alternatives found in the literature on expatriate policies.
Current and Future Treatment Considerations in the Management of Aneurysmal Subarachnoid Hemorrhage
Authors: Rhoney Denise H. , McAllen Karen , Liu-DeRyke Xi
Published: August 2010

Aneurysmal subarachnoid hemorrhage (aSAH) is a type of hemorrhagic stroke that can cause significant morbidity and mortality. Although guidelines have been published to help direct the care of these patients, there is insufficient quality literature regarding the medical and pharmacological management of patients with aSAH. Treatment is divided into 3 categories: supportive therapy, prevention of complications, and treatment of complications. There are numerous pharmacological therapies that are targeted at prevention and treatment of the neurological and medical complications that may arise. Rebleeding, hydrocephalus, cerebral vasospasm, and seizures are the most common neurological complications while the most common medical complications include hyponatremia, pulmonary edema, cardiac arrhythmias, neurogenic stunned myocardium, fever, anemia, infection, hyperglycemia, and venous thromboembolism. Risk factors, clinical presentation, diagnosis, pathophysiology, as well as initial management, prevention, and treatment of complications will be the focus of this discussion.
Early renal damage assessed by the SLICC/ACR damage index is predictor of severe outcome in lupus patients in Pakistan
Authors: Rabbani MA , Habib HB , Islam M. , Ahmad B. , Shah SMA , Tahir S. , Merchant D. , Ahmad A.
Published: August 2010

We investigated patients with systemic lupus erythematosus with the objective of assessing whether early damage accrued in systemic lupus erythematosus as measured by the SLICC/ ACR Damage Index predicts mortality in lupus patients that have been followed prospectively in a single center. Patients with systemic lupus erythematosus from Aga Khan University hospital presenting between 1992 and 2007 were included. This enabled all patients to be potentially followed for at least 10 years. Yearly SLICC/ACR Damage Index scores were determined for each patient. Early damage was defined as a score ≥1, and no damage as a score of 0 at the initial assessment. Kaplan—Meier and Log rank tests were used to compare the survival experience between those with and without damage, with all patients being assessed at 10 years. In this inception cohort 198 patients were identified and were followed for 10 years. Of these, 47 (23.7%) patients had a SLICC/ACR Damage Index score of 0 (no damage) while 151 patients (76.3%) had at least one SLICC/ACR Damage Index item scored (early damage). Mean renal damage score at 1, 5 and 10 years was 0.16, 0.34 and 0.67, respectively. Of lupus patients who exhibited renal damage at their first SLICC/ACR Damage Index assessment, 31% died within 10 years of their illness as compared with only 13% who had no early renal damage (p < 0.003). Mean renal damage score at 1 year after diagnosis was a significant predictor of death within 10 years of diagnosis (p < 0.002). Lupus (2010) 19, 1573—1578.
Gender Differences in Mental Health Problems and Violence Among Chicago Youth
Authors: Wareham Jennifer , Paquette Boots Denise
Published: August 2010

The role of gender is critical when examining how mental health problems affect delinquency over the life course. This study explores gender and developmental pathways to violence for youth participating in the Project on Human Development in Chicago Neighborhoods (PHDCN). Girls having oppositional defiant problems (ODP) were significantly more likely to self-report violence from late childhood through early adolescence; however, only depressive problems mattered for girls during late adolescence. For boys, antisocial personality problems during late adolescence affected violence. Moderating effects of gender were limited to early and late adolescence. Implications regarding gendered solutions when developing strategies targeting youth violence are discussed.
Timing of Applying Electrical Stimulation Is an Important Factor Deciding the Success Rate and Maturity of Regenerating Rat Sciatic Nerves
Authors: Yeh Chia-Chou , Lin Yu-Ching , Tsai Fuu-Jen , Huang Chih-Yang , Yao Chun-Hsu , Chen Yueh-Sheng
Published: August 2010

Background. The timing of electrical stimulation (ES) after peripheral nerve transection may enhance axonal regeneration and functional recovery. Objective. The authors examined whether percutaneous ES at 1 mA and 2 Hz affects regeneration between the proximal and distal nerve stumps. Methods. Four groups of adult rats were subjected to sciatic nerve section followed by repair using silicone rubber conduits across a 10-mm gap. All groups received ES for 15 minutes every other day for 2 weeks. Stimulation was initiated on day 1 following the nerve repair for group A, day 8 for group B, and day 15 for group C. The control group D received no ES. Results. At 6 weeks after surgery in groups B and C, histological evaluations showed a significantly higher number of regenerated myelinated fibers in the sciatic nerve, and the electrophysiological results showed higher levels of reinnervation with relatively larger mean values of amplitudes, durations, and areas of compound muscle action potentials compared with A and D. Conclusion. A short delay in the onset of ES may improve the recovery of a severe peripheral nerve injury, which should be considered as a way of augmenting rehabilitative approaches.
The art of leadership and its fine art shadow
Authors: Barry Daved , Meisiek Stefan
Published: August 2010

In this paper we attempt to bring art and craft together in the enterprise of leadership, first by reframing the art of leadership in light of fine art thinking, and then joining it to notions of craft. With this, we develop an approach to leadership where artistry is closely dependent on, yet distinct from, craft. Finally, we discuss the ramifications of this perspective for leadership practice and research.
Art as experience: An inquiry into art and leadership using dolls and doll-making
Authors: Gayá Wicks Patricia , Rippin Ann
Published: August 2010

This article reflects on an arts-based action inquiry process involving students on an MSc in Management Learning and Change. Following Dewey’s (1934/2005) contention that art is grounded in experience, we adopt a purposefully non-aggrandizing perspective on ‘leadership as art’, arguing that this prompts greater critical attention to possibilities for inclusiveness in these realms of human endeavour. We propose the present inquiry, in which participants were invited to create leadership touchstones, or dolls, as a way of learning about leadership and themselves as leaders. Drawing from therapeutic and psychoanalytic perspectives, we explore dolls’ power to provoke, unsettle and evoke strong reactions on the part of their makers, and demonstrate how these dynamics played out in our inquiry. We highlight the conditions that enabled participants to engage with the tensions and ambiguities raised in ways which held open possibilities for reflexivity. We conclude that leadership, like art, can most constructively engage with the human condition when it is able to hold, not collapse, our experience of the uncanny, the abject, and the other — including the ‘other’ within the ‘self ’ — within the complexities of organizational life.
Use of Written Asthma Action Plans
Authors: Braganza Sandra F. , Sharif Iman
Published: August 2010

Written asthma action plans (WAAPs) are recommended for children with asthma. However, limited studies have examined how parents use WAAPs. The objective of this study was to describe how parents of children with asthma use the WAAPs they receive from their child’s primary care provider and to examine their perceived effectiveness. Investigators surveyed parents of children with asthma at an inner-city academic community health center in the Bronx, New York. A structured parent survey tool was developed to collect information about parents’ use of WAAPs, and a trained physician researcher interviewed parents in person or by phone. Of 428 subjects interviewed, 27% had a WAAP in the home. Children who had a WAAP were older and more likely to have persistent asthma. Most parents reported that they kept the WAAP posted at home or in another safe place. Eighty percent believed that WAAPs were extremely useful, and 55% looked at the WAAP when their child was sick or when they needed to administer medication. Parents viewed the use of WAAPs to be extremely useful in the care of their children with asthma. Our findings support guideline recommendations that primary care providers prescribe WAAPs.
Platelet CD40L mediates thrombotic and inflammatory processes in atherosclerosis
Authors: Lievens Dirk , Zernecke Alma , Seijkens Tom , Soehnlein Oliver , Beckers Linda , Munnix Imke C. A. , Wijnands Erwin , Goossens Pieter , van Kruchten Roger , Thevissen Larissa , Boon Louis , Flavell Richard A. , Noelle Randolph J. , Gerdes Norbert , Biessen Erik A. , Daemen Mat J. A. P. , Heemskerk Johan W. M. , Weber Christian , Lutgens Esther
Published: August 2010

CD40 ligand (CD40L), identified as a costimulatory molecule expressed on T cells, is also expressed and functional on platelets. We investigated the thrombotic and inflammatory contributions of platelet CD40L in atherosclerosis. Although CD40L-deficient (Cd40l−/−) platelets exhibited impaired platelet aggregation and thrombus stability, the effects of platelet CD40L on inflammatory processes in atherosclerosis were more remarkable. Repeated injections of activated Cd40l−/− platelets into Apoe−/− mice strongly decreased both platelet and leukocyte adhesion to the endothelium and decreased plasma CCL2 levels compared with wild-type platelets. Moreover, Cd40l−/− platelets failed to form proinflammatory platelet-leukocyte aggregates. Expression of CD40L on platelets was required for platelet-induced atherosclerosis as injection of Cd40l−/− platelets in contrast to Cd40l+/+ platelets did not promote lesion formation. Remarkably, injection of Cd40l+/+, but not Cd40l−/−, platelets transiently decreased the amount of regulatory T cells (Tregs) in blood and spleen. Depletion of Tregs in mice injected with activated Cd40l−/− platelets abrogated the athero-protective effect, indicating that CD40L on platelets mediates the reduction of Tregs leading to accelerated atherosclerosis. We conclude that platelet CD40L plays a pivotal role in atherosclerosis, not only by affecting platelet-platelet interactions but especially by activating leukocytes, thereby increasing platelet-leukocyte and leukocyte-endothelium interactions.
Blood vessel endothelial VEGFR-2 delays lymphangiogenesis: an endogenous trapping mechanism links lymph- and angiogenesis
Authors: Nakao Shintaro , Zandi Souska , Hata Yasuaki , Kawahara Shuhei , Arita Ryoichi , Schering Alexander , Sun Dawei , Melhorn Mark I. , Ito Yasuhiro , Lara-Castillo Nuria , Ishibashi Tatsuro , Hafezi-Moghadam Ali
Published: August 2010

Angio- and lymphangiogenesis are inherently related processes. However, how blood and lymphatic vessels regulate each other is unknown. This work introduces a novel mechanism explaining the temporal and spatial relation of blood and lymphatic vessels. Vascular endothelial growth factor-A (VEGF-A) surprisingly reduced VEGF-C in the supernatant of blood vessel endothelial cells, suggesting growth factor (GF) clearance by the growing endothelium. The orientation of lymphatic sprouting toward angiogenic vessels and away from exogenous GFs was VEGF-C dependent. In vivo molecular imaging revealed higher VEGF receptor (R)-2 in angiogenic tips compared with normal vessels. Consistently, lymphatic growth was impeded in the angiogenic front. VEGF-C/R-2 complex in the cytoplasm of VEGF-A–treated endothelium indicated that receptor-mediated internalization causes GF clearance from the extracellular matrix. GF clearance by receptor-mediated internalization is a new paradigm explaining various characteristics of lymphatics.
Arsenic trioxide improves event-free and overall survival for adults with acute promyelocytic leukemia: North American Leukemia Intergroup Study C9710
Authors: Powell Bayard L. , Moser Barry , Stock Wendy , Gallagher Robert E. , Willman Cheryl L. , Stone Richard M. , Rowe Jacob M. , Coutre Steven , Feusner James H. , Gregory John , Couban Stephen , Appelbaum Frederick R. , Tallman Martin S. , Larson Richard A.
Published: August 2010

Arsenic trioxide (As2O3) is a highly effective treatment for patients with relapsed acute promyelocytic leukemia (APL); its role as consolidation treatment for patients in first remission has not been defined. We randomized 481 patients (age ≥ 15 years) with untreated APL to either a standard induction regimen of tretinoin, cytarabine, and daunorubicin, followed by 2 courses of consolidation therapy with tretinoin plus daunorubicin, or to the same induction and consolidation regimen plus two 25-day courses of As2O3 consolidation immediately after induction. After consolidation, patients were randomly assigned to one year of maintenance therapy with either tretinoin alone or in combination with methotrexate and mercaptopurine. Ninety percent of patients on each arm achieved remission and were eligible to receive their assigned consolidation therapy. Event-free survival, the primary end point, was significantly better for patients assigned to receive As2O3 consolidation, 80% compared with 63% at 3 years (stratified log-rank test, P < .0001). Survival, a secondary end point, was better in the As2O3 arm, 86% compared with 81% at 3 years (P = .059). Disease-free survival, a secondary end point, was significantly better in the As2O3 arm, 90% compared with 70% at 3 years (P < .0001). The addition of As2O3 consolidation to standard induction and consolidation therapy significantly improves event-free and disease-free survival in adults with newly diagnosed APL. This trial was registered at clinicaltrials.gov (NCT00003934).