bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rift Valley fever in Kenya: history of epizootics and identification of vulnerable districts
Authors: MURITHI R. M. , MUNYUA P. , ITHONDEKA P. M. , MACHARIA J. M. , HIGHTOWER A. , LUMAN E. T. , BREIMAN R. F. , NJENGA M. KARIUKI 
Published: May 2010

SUMMARYSince Kenya first reported Rift Valley fever (RVF)-like disease in livestock in 1912, the country has reported the most frequent epizootics of RVF disease. To determine the pattern of disease spread across the country after its introduction in 1912, and to identify regions vulnerable to the periodic epizootics, annual livestock disease records at the Department of Veterinary Services from 1910 to 2007 were analysed in order to document the number and location of RVF-infected livestock herds. A total of 38/69 (55%) administrative districts in the country had reported RVF epizootics by the end of 2007. During the 1912–1950 period, the disease was confined to a district in Rift Valley province that is prone to flooding and where livestock were raised in proximity with wildlife. Between 1951 and 2007, 11 national RVF epizootics were recorded with an average inter-epizootic period of 3·6 years (range 1–7 years); in addition, all epizootics occurred in years when the average annual rainfall increased by more than 50% in the affected districts. Whereas the first two national epizootics in 1951 and 1955 were confined to eight districts in the Rift Valley province, there was a sustained epizootic between 1961 and 1964 that spread the virus to over 30% of the districts across six out of eight provinces. The Western and Nyanza provinces, located on the southwestern region of the country, had never reported RVF infections by 2007. The probability of a district being involved in a national epizootic was fivefold higher (62%) in districts that had previously reported disease compared to districts that had no prior disease activity (11%). These findings suggests that once introduced into certain permissive ecologies, the RVF virus becomes enzootic, making the region vulnerable to periodic epizootics that were probably precipitated by amplification of resident virus associated with heavy rainfall and flooding.
THE LARGE-TIME SOLUTION OF A NONLINEAR FOURTH-ORDER EQUATION INITIAL-VALUE PROBLEM I. INITIAL DATA WITH A DISCONTINUOUS EXPANSIVE STEP
Authors: LEACH J. A. , BASSOM ANDREW P. 
Published: May 2010

AbstractIn this paper we consider an initial-value problem for the nonlinear fourth-order partial differential equation ut+uux+γuxxxx=0, −∞<x<∞, t>0, where x and t represent dimensionless distance and time respectively and γ is a negative constant. In particular, we consider the case when the initial data has a discontinuous expansive step so that u(x,0)=u0(>0) for x≥0 and u(x,0)=0 for x<0. The method of matched asymptotic expansions is used to obtain the large-time asymptotic structure of the solution to this problem which exhibits the formation of an expansion wave. Whilst most physical applications of this type of equation have γ>0, our calculations show how it is possible to infer the large-time structure of a whole family of solutions for a range of related equations.
THE SUBEXPONENTIAL PRODUCT CONVOLUTION OF TWO WEIBULL-TYPE DISTRIBUTIONS
Authors: LIU YAN , TANG QIHE 
Published: May 2010

AbstractLet X1 and X2 be two independent and nonnegative random variables with distributions F1 and F2, respectively. This paper proves that if both F1 and F2 are of Weibull type and fulfill certain easily verifiable conditions, then the distribution of the product X1X2, called the product convolution of F1 and F2, belongs to the class 𝒮* and, hence, is subexponential.
Hospital prices and market structure in the hospital and insurance industries
Authors: Moriya Asako S. , Vogt William B. , Gaynor Martin 
Published: May 2010

AbstractThere has been substantial consolidation among health insurers and hospitals, recently, raising questions about the effects of this consolidation on the exercise of market power. We analyze the relationship between insurer and hospital market concentration and the prices of hospital services. We use a national US dataset containing transaction prices for health care services for over 11 million privately insured Americans. Using three years of panel data, we estimate how insurer and hospital market concentration are related to hospital prices, while controlling for unobserved market effects. We find that increases in insurance market concentration are significantly associated with decreases in hospital prices, whereas increases in hospital concentration are non-significantly associated with increases in prices. A hypothetical merger between two of five equally sized insurers is estimated to decrease hospital prices by 6.7%.
Chemical structure, network topology, and porosity effects on the mechanical properties of Zeolitic Imidazolate Frameworks
Authors: Tan Jin Chong , Bennett Thomas D. , Cheetham Anthony K. 
Published: May 2010

The mechanical properties of seven zeolitic imidazolate frameworks (ZIFs) based on five unique network topologies have been systematically characterized by single-crystal nanoindentation studies. We demonstrate that the elastic properties of ZIF crystal structures are strongly correlated to the framework density and the underlying porosity. For the systems considered here, the elastic modulus was found to range from 3 to 10 GPa, whereas the hardness property lies between 300 MPa and 1.1 GPa. Notably, these properties are superior to those of other metal–organic frameworks (MOFs), such as MOF-5. In substituted imidazolate frameworks, our results show that their mechanical properties are mainly governed by the rigidity and bulkiness of the substituted organic linkages. The framework topology and the intricate pore morphology can also influence the degree of mechanical anisotropy. Our findings present the previously undescribed structure-mechanical property relationships pertaining to hybrid open frameworks that are important for the design and application of new MOF materials.
Superconducting high-pressure phases of disilane
Authors: Jin Xilian , Meng Xing , He Zhi , Ma Yanming , Liu Bingbing , Cui Tian , Zou Guangtian , Mao Ho-kwang 
Published: May 2010

High-pressure structures of disilane (Si
2
H
6
) are investigated extensively by means of first-principles density functional theory and a random structure-searching method. Three metallic structures with
P
-1,
Pm
-3
m
, and
C
2/
c
symmetries are found, which are more stable than those of XY
3
-type candidates under high pressure. Enthalpy calculations suggest a remarkably wide decomposition (Si and H
2
) pressure range below 135 GPa, above which three metallic structures are stable. Perturbative linear-response calculations for
Pm
-3
m
disilane at 275 GPa show a large electron-phonon coupling parameter
λ
of 1.397 and the resulting superconducting critical temperature beyond the order of 10
2
K.
Increased Genomic Copy Number of DEFA1/DEFA3 Is Associated with Susceptibility to Severe Sepsis in Chinese Han Population
Authors: Chen QiXing , Hakimi Matthew , Wu ShuiJing , Jin Yue , Cheng BaoLi , Wang HaiHong , Xie GuoHao , Ganz Tomas , Linzmeier Rose M. , Fang XiangMing 
Published: May 2010

Background
Human neutrophil peptides 1-3 are endogenous cationic antimicrobial peptides implicated in host defense against microbes. The genes encoding human neutrophil peptides 1-3 (DEFA1/DEFA3) exhibit copy number variations. This study was designed to determine whether DEFA1/DEFA3 copy number variations conferred susceptibility to infection-induced complications such as severe sepsis.

Methods
This case-control study was performed in 179 patients with severe sepsis and 233 healthy blood donors and was replicated in an independent cohort of 112 cases and 118 controls. Plasma levels of human neutrophil peptides 1-3, tumor necrosis factor-alpha, interleukin-6, and interleukin-10 were detected.

Results
The genotype of DEFA1/DEFA3 with more than eight copies was more frequent in patients with severe sepsis than in controls (55.9% vs. 31.3%; P = 1.13 x 10, odds ratio 2.77, 95% confidence interval 1.85-4.16). After adjustment for age and gender, logistic regression analysis confirmed the association of the genotype of more than eight copies with an increased risk of severe sepsis (P = 2.25 x 10, odds ratio 2.66, 95% confidence interval 1.69-4.19). This established association was replicated in a second age- and gender-matched case-control cohort (P = 0.02, odds ratio 1.90, 95% confidence interval 1.11-3.27). Furthermore, compared with those with fewer copies, the patients carrying more than eight copies of DEFA1/DEFA3 presented significantly lower plasma levels of human neutrophil peptides 1-3, tumor necrosis factor-alpha, interleukin-6, and interleukin-10 (P = 0.039, 0.017, 0.030, and 0.029, respectively).

Conclusions
DEFA1/DEFA3 is an important genetic component participating in host immune response to severe sepsis. A higher copy number of DEFA1/DEFA3 (>8 copies) is significantly associated with the risk of severe sepsis.
Prognostic Implications of Asymptomatic Left Ventricular Dysfunction in Patients Undergoing Vascular Surgery
Authors: Flu Willem-Jan , van Kuijk Jan-Peter , Hoeks Sanne E. , Kuiper Ruud , Schouten Olaf , Goei Dustin , Elhendy Abdou , Verhagen Hence J. M. , Thomson Ian R. , Bax Jeroen J. , Fleisher Lee A. , Poldermans Don 
Published: May 2010

Background
The prognostic value of heart failure symptoms on postoperative outcome is well acknowledged in perioperative guidelines. The prognostic value of asymptomatic left ventricular (LV) dysfunction remains unknown. This study evaluated the prognostic implications of asymptomatic LV dysfunction in vascular surgery patients assessed with routine echocardiography.

Methods
Echocardiography was performed preoperatively in 1,005 consecutive vascular surgery patients. Systolic LV dysfunction was defined as LV ejection fraction less than 50%. Ratio of mitral-peak velocity during early and late filling, pulmonary vein flow, and deceleration time was used to diagnose diastolic LV dysfunction. Troponin-T measurements and electrocardiograms were performed routinely perioperatively. Multivariate regression analyses evaluated the relation between LV function and the study endpoints, 30-day cardiovascular events, and long-term cardiovascular mortality.

Results
Left ventricular dysfunction was diagnosed in 506 (50%) patients of which 80% were asymptomatic. In open vascular surgery (n = 649), both asymptomatic systolic and isolated diastolic LV dysfunctions were associated with 30-day cardiovascular events (odds ratios 2.3, 95% confidence interval [CI] 1.4-3.6 and 1.8, 95% CI 1.1-2.9, respectively) and long-term cardiovascular mortality (hazard ratios 4.6, 95% CI 2.4-8.5 and 3.0, 95% CI 1.5-6.0, respectively). In endovascular surgery (n = 356), only symptomatic heart failure was associated with 30-day cardiovascular events (odds ratio 1.8, 95% CI 1.1-2.9) and long-term cardiovascular mortality (hazard ratio 10.3, 95% CI 5.4-19.3).

Conclusions
This study demonstrated that asymptomatic LV dysfunction is predictive for 30-day and long-term cardiovascular outcome in open vascular surgery patients. These data suggest that preoperative risk stratification should include not only solely heart failure symptoms but also routine preoperative echocardiography to risk stratify open vascular surgery patients.
Systematic review: role of acid, weakly acidic and weakly alkaline reflux in gastro‐oesophageal reflux disease
Authors: Boeckxstaens G. E. , Smout A. 
Published: May 2010

Aliment Pharmacol Ther 2010; 32: 334–343SummaryBackground  The importance of weakly acidic and weakly alkaline reflux in gastro‐oesophageal reflux disease (GERD) is gaining recognition.Aim  To quantify the proportions of reflux episodes that are acidic (pH <4), weakly acidic (pH 4–7) and weakly alkaline (pH >7) in adult patients with GERD, and to evaluate their correlation with symptoms.Methods  Studies were identified by systematic PubMed and Embase searches. Data are presented as sample‐size weighted means and 95% confidence intervals.Results  In patients with GERD taking a proton pump inhibitor (PPI), 80% (76–84%) of reflux episodes were weakly acidic or weakly alkaline and 83% (78–88%) of reflux symptom episodes were associated with weakly acidic or weakly alkaline reflux episodes. In patients with GERD not taking a PPI, 63% (59–67%) of reflux episodes were acidic and 72% (57–87%) of reflux symptom episodes were associated with acid reflux episodes. Six studies presented data separately for weakly alkaline reflux, which accounted for <5% of all reflux episodes, both on and off PPI therapy.Conclusions  Weakly acidic reflux underlies the majority of reflux episodes in patients with GERD on PPI therapy, and is the main cause of reflux symptoms occurring despite PPI therapy.
Immune regulatory effects of simvastatin on regulatory T cell-mediated tumour immune tolerance
Authors: Lee K J , Moon J Y , Choi H K , Kim H O , Hur G Y , Jung K H , Lee S Y , Kim J H , Shin C , Shim J J , In K H , Yoo S H , Kang K H , Lee S Y 
Published: May 2010

Summary
Statins are potent inhibitors of hydroxyl-3-methylglutaryl co-enzyme A (HMG-CoA) reductase, and have emerged as potential anti-cancer agents based on preclinical evidence. In particular, compelling evidence suggests that statins have a wide range of immunomodulatory properties. However, little is known about the role of statins in tumour immune tolerance. Tumour immune tolerance involves the production of immunosuppressive molecules, such as interleukin (IL)-10, transforming growth factor (TGF)-β and indoleamine-2,3-dioxygenase (IDO) by tumours, which induce a regulatory T cell (Treg) response. In this study, we investigated the effect of simvastatin on the production of IL-10, TGF-β and IDO production and the proliferation of Tregs using several cancer cell lines, and Lewis lung cancer (3LL) cells-inoculated mouse tumour model. Simvastatin treatment resulted in a decrease in the number of cancer cells (3LL, A549 and NCI-H292). The production of the immune regulatory markers IL-10, TGF-β in 3LL and NCI-H292 cells increased after treatment with simvastatin. The expression of IDO and forkhead box P3 (FoxP3) transcription factor was also increased in the presence of simvastatin. In a murine 3LL model, there were no significant differences in tumour growth rate between untreated and simvastatin-treated mice groups. Therefore, while simvastatin had an anti-proliferative effect, it also exhibited immune tolerance-promoting properties during tumour development. Thus, due to these opposing actions, simvastatin had no net effect on tumour growth.
Clusterin expression is associated with decreased disease‐free survival of patients with colorectal carcinomas
Authors: Redondo Maximino , Rodrigo Isabel , Alcaide Julia , Tellez Teresa , Roldan María J , Funez Rafael , Diaz‐Martin Aurelio , Rueda Antonio , Jiménez Eugenio 
Published: May 2010

Redondo M, Rodrigo I, Alcaide J, Tellez T, Roldan M J, Funez R, Diaz‐Martin A, Rueda A & Jiménez E (2010) Histopathology 56, 932–936 Clusterin expression is associated with decreased disease‐free survival of patients with colorectal carcinomasAims:  It has been demonstrated that increased clusterin expression is involved in malignant progression and that anticlusterin treatment leads to selective apoptosis. The aim of this study was to determine the clinicopathological significance of clusterin expression in human colorectal carcinomas.Methods and results:  The expression of clusterin was examined in 31 adenomas and 103 colorectal carcinomas. Normal epithelial cells were always negative for clusterin expression, but clusterin expression was present in 16% (5/31) of adenomas and this percentage increased in colorectal carcinomas (30%, 31/103). Immunopositivity always presented an apical cytoplasmic pattern. The expression level of clusterin did not correlate with age, gender, grade or stage. However, its expression was significantly associated with a decrease in disease‐free survival (P < 0.05). In a multivariate Cox proportional hazards model, clusterin expression remained a significant independent predictor.Conclusions:  Clusterin expression may have a role in colonic carcinogenesis and may help identify patients with more aggressive tumours who may benefit from targeted therapy.
Match or mismatch: the influence of phenology on size‐dependent life history and divergence in population structure
Authors: Borcherding Jost , Beeck Peter , DeAngelis Donald L. , Scharf Werner R. 
Published: May 2010

Summary 1. In gape‐limited predators, body size asymmetries determine the outcome of predator–prey interactions. Due to ontogenetic changes in body size, the intensity of intra‐ and interspecific interactions may change rapidly between the match situation of a predator–prey system and the mismatch situation in which competition, including competition with the prey, dominates. 2. Based on a physiologically structured population model using the European perch (Perca fluviatilis), analysis was performed on how prey density (bream, Abramis brama), initial size differences in the young‐of‐the‐year (YOY) age cohort of the predator, and phenology (time‐gap in hatching of predator and prey) influence the size structure of the predator cohort. 3. In relation to the seasonality of reproduction, the match situation of the predator–prey system occurred when perch hatched earlier than bream and when no gape‐size limitations existed, leading to decreased size divergence in the predator age cohort. Decreased size divergence was also found when bream hatched much earlier than perch, preventing perch predation on bream occurring, which, in turn, increased the competitive interaction of the perch with bream for the common prey, zooplankton; i.e. the mismatch situation in which also the mean size of the age cohort of the predator decreased. 4. In between the total match and the mismatch, however, only the largest individuals of the perch age cohort were able to prey on the bream, while smaller conspecifics got trapped in competition with each other and with bream for zooplankton, leading to enlarged differences in growth that increased size divergence. 5. The modelling results were combined with 7 years of field data in a lake, where large differences in the length‐frequency distribution of YOY perch were observed after their first summer. These field data corroborate that phenology and prey density per predator are important mechanisms in determining size differences within the YOY age cohort of the predator. 6. The results demonstrate that the switch between competitive interactions and a predator–prey relationship depended on phenology. This resulted in pronounced size differences in the YOY age cohort, which had far‐reaching consequences for the entire predator population.
Drivers of growth variation in juvenile Atlantic salmon (Salmo salar): an elasticity analysis approach
Authors: Davidson R. Scott , Letcher Benjamin H. , Nislow Keith H. 
Published: May 2010

Abstract 1. Estimating the relative importance of factors affecting key vital rates is an essential challenge for population ecology. In spite of a large literature on individual growth rates of north temperate‐zone fishes, relative effect sizes for the wide range of abiotic and biotic factors affecting fish growth are not well characterized, strongly limiting our ability to predict the effects of environmental change on fish populations. 2. We applied generalized linear mixed models to data from a long‐term (nine cohorts over 10 years) individual‐based (7685 records from 4203 individuals) study of stream‐dwelling juvenile Atlantic salmon (Salmo salar) to estimate the relative importance and interactive effects of stream discharge, water temperature and population density on season‐specific growth rates. The model explained a large proportion (r2 = 0·95) of observed variation in growth. 3. Elasticity analysis was used to estimate the relative importance of model variables on growth in length for Atlantic salmon between age 0+ autumn and the end of age 1+ winter. Effects of population density were substantially weaker than effects of discharge and temperature across all seasons. Opposing among‐season temperature effects reduced the overall importance of temperature on growth in contrast to discharge, where effects were generally positive among seasons. Consistent among‐season effects and a greater range of observed variation combined to increase the effect of discharge on growth compared to temperature. 4. These results suggest that robust predictions of body growth in north temperate stream fishes will need to include season‐specific estimates of variation in both abiotic (temperature and discharge) and biotic (density) factors, but that variation in discharge will dominate growth responses.
Vertical distribution, flight behaviour and evolution of wing morphology in Morpho butterflies
Authors: DeVries P. J. , Penz Carla M. , Hill Ryan I. 
Published: May 2010

Summary 1. Flight is a key innovation in the evolution of insects that is crucial to their dispersal, migration, territoriality, courtship and predator avoidance. Male butterflies have characteristic territoriality and courtship flight behaviours, and females use a characteristic flight behaviour when searching for host plants. This implies that selection acts on wing morphology to maximize flight performance for conducting important behaviours among sexes. 2. Butterflies in the genus Morpho are obvious components of neotropical forests, and many observations indicate that they show two broad categories of flight behaviour and flight height. Although species can be categorized as using gliding or flapping flight, and flying at either canopy or understorey height, the association of flight behaviour and flight height with wing shape evolution has never been explored. 3. Two clades within Morpho differ in flight behaviour and height. Males and females of one clade inhabit the forest understorey and use flapping flight, whereas in the other clade, males use gliding flight at canopy level and females use flapping flight in both canopy and understorey. 4. We used independent contrasts to answer whether wing shape is associated with flight behaviour and height. Given a single switch to canopy habitation and gliding flight, we compared contrasts for the node at which the switch to canopy flight occurred with the distribution of values in the two focal clades. We found significant changes in wing shape at the transition to canopy flight only in males, and no change in size for either sex. A second node within the canopy clade suggests that other factors may also be involved in wing shape evolution. Our results reinforce the hypothesis that natural selection acts differently on male and female butterfly wing shape and indicate that the transition to canopy flight cannot explain all wing shape diversity in Morpho. 5. This study provides a starting point for characterizing evolution of wing morphology in forest butterflies in the contexts of habitat selection and flight behaviour. Further, these observations suggest that exploring wing shape evolution for canopy and understorey species in other insects may help understand the effects of habitat destruction on biological diversity.