bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Affine‐Invariant Generalization of the Wilcoxon Signed‐Rank Test for the Bivariate Location Problem
Authors: Larocque Denis , Tardif Serge , Eeden Constance van 
Published: December 2004

AbstractThis paper proposes an affine‐invariant test extending the univariate Wilcoxon signed‐rank test to the bivariate location problem. It gives two versions of the null distribution of the test statistic. The first version leads to a conditionally distribution‐free test which can be used with any sample size. The second version can be used for larger sample sizes and has a limiting χ22 distribution under the null hypothesis. The paper investigates the relationship with a test proposed by Jan & Randles (1994). It shows that the Pitman efficiency of this test relative to the new test is equal to 1 for elliptical distributions but that the two tests are not necessarily equivalent for non‐elliptical distributions. These facts are also demonstrated empirically in a simulation study. The new test has the advantage of not requiring the assumption of elliptical symmetry which is needed to perform the asymptotic version of the Jan and Randles test.
Minimal Basis for a Connected Markov Chain over 3 × 3 ×K Contingency Tables with Fixed Two‐Dimensional Marginals
Authors: Aoki Satoshi , Takemura Akimichi 
Published: December 2004

AbstractThis paper considers a connected Markov chain for sampling 3 × 3 ×K contingency tables having fixed two‐dimensional marginal totals. Such sampling arises in performing various tests of the hypothesis of no three‐factor interactions. A Markov chain algorithm is a valuable tool for evaluating P‐values, especially for sparse datasets where large‐sample theory does not work well. To construct a connected Markov chain over high‐dimensional contingency tables with fixed marginals, algebraic algorithms have been proposed. These algorithms involve computations in polynomial rings using Gröbner bases. However, algorithms based on Gröbner bases do not incorporate symmetry among variables and are very time‐consuming when the contingency tables are large. We construct a minimal basis for a connected Markov chain over 3 × 3 ×K contingency tables. The minimal basis is unique. Some numerical examples illustrate the practicality of our algorithms.
Time course of capillary structure changes in rat skeletal muscle following strenuous eccentric exercise
Authors: Kano Y. , Sampei K. , Matsudo H. 
Published: December 2004

AbstractAim:  We examined the time course of capillary structure changes in rat skeletal muscle at 1, 3 and 7 days after strenuous eccentric exercise.Methods:  The right gastrocnemius muscles of anaesthetized male Wistar rats were subjected to 300 controlled eccentric contractions using electrical stimulation. The contralateral gastrocnemius muscle was used as control. All morphometric parameters were determined in in situ perfused gastrocnemius muscles in red (Gr, predominantly slow‐twitch fibre) and white (Gw, predominantly fast‐twitch fibre) portions.Results:  Muscle fibre damage was evident on days 1, 3 and 7 in Gr (29.3–53.9% damaged fibres) and Gw (58.9–86.8% damaged fibres) of exercised legs. Electron micrographs of transverse sections did not display collapsed or obstructed capillaries in exercised legs, and capillary endothelial cells retained their normal structures. However, capillary luminal shapes and area were altered in exercised legs on days 1 and 3. The ratio between minimal and maximal capillary diameter in a transverse section (i.e. luminal ellipticity) significantly differed when comparing control (Gr, 0.75 ± 0.02; Gw, 0.79 ± 0.03) and exercised legs (Gr, 0.65 ± 0.03; Gw, 0.66 ± 0.04) at 1 day after exercise. The mean capillary luminal area was significantly increased in exercised legs after 1 day (Gw, +24.3%) and 3 days (Gr, +31.9%; Gw, +62.2%) compared with control.Conclusion:  We conclude that (1) capillary endothelial cell structure was maintained in damaged muscles, (2) changes in capillary lumen shapes and distensibility occur in the degenerated muscle up to 3 days after the eccentric contraction period.
Ca2+‐activated Cl− current reduces transmural electrical heterogeneity within the rabbit left ventricle
Authors: Verkerk A. O. , Tan H. L. , Ravesloot J. H. 
Published: December 2004

AbstractObjective:  Various cationic membrane channels contribute to the heterogeneity of action potential configuration between the transmural layers of the left ventricle. The role of anionic membrane channels is less intensively studied. We investigated the role of the Ca2+‐activated Cl− current, ICl(Ca), in transmural electrical heterogeneity.Methods and Results:  We determined the density of ICl(Ca) and its physiological role in subepicardial and subendocardial ventricular myocytes of rabbit using the patch‐clamp technique. ICl(Ca) was measured as the 4,4′diisothiocyanatostilbene‐2,2′‐disulphonic acid (DIDS) sensitive current. The current–voltage relationships and the densities of ICl(Ca) were similar in subepicardial and subendocardial myocytes. However, the functional role of ICl(Ca) exhibited striking differences. In subendocardial myocytes, blockade of ICl(Ca) by DIDS increased action potential duration (APD) significantly at all measured stimulus frequencies (3.33–0.2 Hz). In subepicardial myocytes, ICl(Ca) blockade increased APD only at 3.33 Hz, but not at the lower stimulus frequencies. At 1 Hz, ICl(Ca) blockade in subepicardial myocytes only caused an APD increase when the transient outward K+ current, Ito1, was blocked.Conclusions:  The densities and gating properties of ICl(Ca) are similar in subepicardial and subendocardial myocytes. ICl(Ca) contributes to APD shortening in subendocardial, but not in subepicardial myocytes except at 3.33 Hz. These differences in functional expression of ICl(Ca) reduce the electrical heterogeneity in rabbit left ventricle.
Patterns of ecstasy use in Australia: findings from a national household survey
Authors: Degenhardt Louisa , Barker Bridget , Topp Libby 
Published: December 2004

ABSTRACTAim  To examine the patterns, correlates and context of ‘recent’ (preceding 12 months) ecstasy use using data from a nationally representative sample of Australians interviewed in 2001.Design  Data were analysed from the 2001 National Drug Strategy Household Survey, a multi‐stage probability sample of Australians aged 14 years or older. The focus was on ecstasy use among 14–19‐year‐olds and 20–29‐year‐olds, as the prevalence of recent use is highest among these groups. Recent ecstasy users were compared to those who had not used in the preceding 12 months and those who had never tried ecstasy (‘others’) on a range of demographic and drug use variables. Comparisons were also drawn between the patterns and context of ecstasy use of the two groups of recent ecstasy users (users aged between 14–19 and 20–29 years).Findings  In 2001, 6.1% of Australians aged 14 years or older reported life‐time ecstasy use, and 2.9% reported recent use. One in 10 (10.4%) of 20–29‐year‐olds and 5.0% of 14–19‐year‐olds had used ecstasy recently. Although there were few demographic differences between recent users and others, compared to those who had not recently used ecstasy, recent ecstasy users were more likely to have used a range of other drugs. Although recent ecstasy users of both age groups could be characterized as polydrug users, 20–29‐year‐old users were more likely to use other drugs concurrently with ecstasy.Conclusions  Following cannabis and amphetamines, ecstasy is the third most widely used illicit drug in Australia. Other than a greater likelihood of having used other drugs, few demographic variables appear to distinguish recent ecstasy users from others. Australian users in their 20s use ecstasy within a context of greater polydrug use than those in their teens. Although most ecstasy users described a pattern of occasional use, minorities reported weekly use, and difficulties in reducing their use despite wishing to do so. There is a need to develop interventions to assist problematic ecstasy users to reduce their use should they wish to do so and to increase education about the potential risks of combining ecstasy with other drugs.
A postmarketing study of relative abuse liability of hypnotic sedative drugs
Authors: Jaffe Jerome H. , Bloor Roger , Crome Ilana , Carr Malcolm , Alam Farrukh , Simmons Arnol , Meyer Roger E. 
Published: December 2004

ABSTRACTAims  To demonstrate the utility of postmarketing studies using in‐treatment drug and alcohol abusers as informants for assessing the relative abuse liability of sedative–hypnotic drugs.Design  A survey was conducted that ascertained exposure to a variety of drugs with hypnotic/sedative properties and elicited subjective evaluations indicative of abuse liability.Methods  Complete data were obtained from 297 admissions (78% male) to three addiction treatment sites in the United Kingdom. Subjects were asked 15 questions about 12 different drugs, including five benzodiazepines, three antidepressants, two non‐benzodiazepine hypnotics and two antihistamines (plus one fictitious drug). Three of the benzodiazepines (diazepam, nitrazipam, temazepam) emerged as having substantially more abuse liability than any of the other drugs tested, as revealed by higher scores on abuse liability items (purchased on street, taken to get high, like drug, potential for addiction to drug). The antihistamines (chlorpheniramine, diphenhydramine) had lowest abuse liability profiles, while the antidepressants (amitriptyline, fluoxetine, trazadone) and non‐benzodiazepine hypnotics (zolpidem, zopiclone) had similar profiles.Conclusion  This pilot study suggests that postmarketing information on hypnotic drug use obtained from drug addicts entering treatment produces data consistent with other measures of abuse liability. The data suggest that the risk of misuse of newer non‐benzodiazepine hypnotics may be less than that of benzodiazepine drugs, and similar to that of sedating antidepressants. The new methodology may serve to clarify or validate premarketing abuse liability data, and may help to inform the regulatory process and physician practice.
Uptake and adherence to highly active antiretroviral therapy among HIV‐infected people with alcohol and other substance use problems: the impact of substance abuse treatment
Authors: Palepu Anita , Horton Nicholas J. , Tibbetts Nicole , Meli Seville , Samet Jeffrey H. 
Published: December 2004

ABSTRACTAim  We examined the association of substance abuse treatment with uptake, adherence and virological response to highly active antiretroviral therapy (HAART) among HIV‐infected people with a history of alcohol problems.Design  Prospective cohort study.Methods  A standardized questionnaire was administered to 349 HIV‐infected participants with a history of alcohol problems regarding demographics, substance use, use of substance abuse treatment and uptake of and adherence to HAART. These subjects were followed every 6 months for up to seven occasions. We defined substance abuse treatment services as any of the following in the past 6 months: 12 weeks in a half‐way house or residential facility; 12 visits to a substance abuse counselor or mental health professional; or participation in any methadone maintenance program. Our outcome variables were uptake of antiretroviral therapy, 30‐day self‐reported adherence and HIV viral load suppression.Findings  At baseline, 59% (205/349) of subjects were receiving HAART. Engagement in substance abuse treatment was independently associated with receiving antiretroviral therapy (adjusted OR; 95% CI: 1.70; 1.03–2.83). Substance abuse treatment was not associated with 30‐day adherence or HIV viral load suppression. More depressive symptoms (0.48; 0.32–0.78) and use of drugs or alcohol in the previous 30 days (0.17; 0.11–0.28) were associated with worse 30‐day adherence. HIV viral load suppression was positively associated with higher doses of antiretroviral medication (1.29; 1.15–1.45) and older age (1.04; 1.00–1.07) and negatively associated with use of drugs or alcohol in the previous 30 days (0.51; 0.33–0.78).Conclusion  Substance abuse treatment was associated with receipt of HAART; however, it was not associated with adherence or HIV viral load suppression. Substance abuse treatment programs may provide an opportunity for HIV‐infected people with alcohol or drug problems to openly address issues of HIV care including enhancing adherence to HAART.
Anti‐hyperalgesic effect of octreotide in patients with irritable bowel syndrome
Authors: Schwetz I. , Naliboff B. , Munakata J. , Lembo T. , Chang L. , Matin K. , Ohning G. , Mayer E. A. 
Published: December 2004

SummaryBackground : Octreotide has been found to be beneficial in the treatment of chronic pain, although the mechanisms underlying its therapeutic effect are incompletely understood.Aims : To assess the effect of octreotide on perceptual responses to rectal distension in irritable bowel syndrome patients and healthy controls at baseline and following the experimental induction of rectal hyperalgesia.Methods : In study 1, rectal perception thresholds for discomfort were determined in seven irritable bowel syndrome patients and eight healthy controls on three separate days using a computer‐controlled barostat. Subjects received saline, low‐dose and high‐dose octreotide in a random double‐blind fashion. In study 2, perceptual responses to rectal distension were obtained in nine irritable bowel syndrome patients and seven controls before and after repetitive high‐pressure mechanical sigmoid stimulation.Results : Octreotide increased the discomfort thresholds in irritable bowel syndrome patients, but not in controls, without changing rectal compliance. Repetitive sigmoid stimulation resulted in decreased rectal discomfort thresholds in the patient group only. In irritable bowel syndrome patients, octreotide prevented the sensitizing effect of repetitive sigmoid stimulation on rectal discomfort thresholds.Conclusions : Octreotide effectively increased discomfort thresholds in irritable bowel syndrome patients, but not in controls, at baseline and during experimentally induced rectal hyperalgesia. These findings suggest that octreotide exerts primarily an anti‐hyperalgesic rather than analgesic effect on visceral perception.
Regional application of PnET‐N‐DNDC for estimating the N2O source strength of tropical rainforests in the Wet Tropics of Australia
Authors: Kiese Ralf , Li Changsheng , Hilbert David W. , Papen Hans , Butterbach‐Bahl Klaus 
Published: December 2004

AbstractIn contrast to the significant importance of tropical rainforest ecosystems as one of the major sources within the global atmospheric N2O budget (2.2–3.7 Tg N yr−1), regional estimates of their N2O source strength are still limited and highly uncertain. To contribute toward more reliable estimates of the N2O source strength of tropical rainforest ecosystems on a regional scale, we modified a process‐oriented biogeochemical model, PnET‐N‐DNDC, and parameterized it to simulate C and N turnover and associated N2O emissions in and from tropical rainforest ecosystems. Model modifications included: (1) new parameterizations associated with plant physiology and soil hydrology and the addition of algorithms relating daily leaf litterfall to water stress as well as to daily rainfall to account for the effects of heavy rainfall damage; (2) the development of a denitrifier activity index that depends on soil moisture conditions and influences N turnover by denitrification; and (3) the addition of a biological N fixation algorithm. Daily simulated N2O emissions based on site data were in good agreement (model efficiencies up to 0.83) with field observations in the Wet Tropics of Australia and Costa Rica. The model was even able to reproduce the highly dynamic pattern of N2O emissions with short‐term increases during the wet season. Sensitivity analyses demonstrated that the PnET‐N‐DNDC model was sensitive to changes in soil properties such as pH, clay content, soil organic carbon and climatic factors such as rainfall and temperature. By linking the PnET‐N‐DNDC model to a geographic information systems database, tropical rainforests in a 9000 km2 area of the Wet Tropics of Australia are estimated to emit 962 t N2O‐N yr−1 (2.4 kg N2O‐N ha−1 yr−1) between July 1997 and June 1998.
Do changes in climate patterns in wintering areas affect the timing of the spring arrival of trans‐Saharan migrant birds?
Authors: Gordo Oscar , Brotons Lluís , Ferrer Xavier , Comas Pere 
Published: December 2004

AbstractThe life cycles of plants and animals are changing around the world in line with the predictions originated from hypotheses concerning the impact of global warming and climate change on biological systems. Commonly, the search for ecological mechanisms behind the observed changes in bird phenology has focused on the analysis of climatic patterns from the species breeding grounds. However, the ecology of bird migration suggests that the spring arrival of long‐distance migrants (such as trans‐Saharan birds) is more likely to be influenced by climate conditions in wintering areas given their direct impact on the onset of migration and its progression. We tested this hypothesis by analysing the first arrival dates (FADs) of six trans‐Saharan migrants (cuckooCuculus canorus, swiftApus apus, hoopoeUpupa epops, swallowHirundo rustica, house martinDelichon urbicaand nightingaleLuscinia megarhynchos), in a western Mediterranean area since from 1952 to 2003. By means of multiple regression analyses, FADs were analysed in relation to the monthly temperature and precipitation patterns of five African climatic regions south of the Sahara where species are thought to overwinter and from the European site from where FADs were collected. We obtained significant models for five species explaining 9–41% of the variation in FADs. The interpretation of the models suggests that: (1) The climate in wintering quarters, especially the precipitation, has a stronger influence on FADs than that in the species' potential European breeding grounds. (2) The accumulative effects of climate patterns prior to migration onset may be of considerable importance since those climate variables that served to summarize climate patterns 12 months prior to the onset of migration were selected by final models. (3) Temperature and precipitation in African regions are likely to affect departure decision in the species studied through their indirect effects on food availability and the build‐up of reserves for migration. Our results concerning the factors that affect the arrival times of trans‐Saharan migrants indicate that the effects of climate change are more complex than previously suggested, and that these effects might have an interacting impact on species ecology, for example by reversing ecological pressures during species' life cycles.
The response of heterotrophic CO2flux to soil warming
Authors: Eliasson Peter E. , McMurtrie Ross E. , Pepper David A. , Strömgren Monika , Linder Sune , Ågren Göran I. 
Published: December 2004

AbstractIn a forest ecosystem at steady state, net carbon (C) assimilation by plants and C loss through soil and litter decomposition by heterotrophic organisms are balanced. However, a perturbation to the system, such as increased mean soil temperature, will lead to faster decay, enhancing CO2release from decomposers, and thus upsetting the balance. Recentin situexperiments have indicated that the stimulation of soil respiration following a step increase in annual average soil temperature declines over time. One possible explanation for this decline may be changes in substrate availability. This hypothesis is examined by using the ecosystem model G'DAY, which simulates C and nitrogen (N) dynamics in plants and soil.We applied the model to observations from a soil‐warming experiment in a Norway spruce (Picea abies(L.) Karst.) stand by simulating a step increase of soil temperature. The model provided a good qualitative reproduction of the observed reduction of heterotrophic respiration (Rh) under sustained warming. The simulations showed how the combined effects of faster turnover and reduced substrate availability lead to a transient increase ofRh. The simulated annual increase inRhfrom soil was 60% in the first year after perturbation but decreased to 30% after a decade.One conclusion from the analysis of the simulations is thatRhcan decrease even though the temperature response function for decomposition remains unchanged. G'DAY suggests that acclimation ofRhto soil warming is partly an effect of substrate depletion of labile C pools during the first decade of warming as a result of accelerated rates of mineralization. The response is attributed mainly to changing levels of C in pools with short time constants, reflecting the importance of high‐quality soil C fractions. Changes of the structure or physiology of the decomposer community were not invoked. Therefore, it becomes a question of definition whether the simulated dynamics of the declining response of CO2release to the warming should be named acclimation or seen as a natural part of the system dynamics.
Global climate change and soil carbon stocks; predictions from two contrasting models for the turnover of organic carbon in soil
Authors: Jones Chris , McConnell Claire , Coleman Kevin , Cox Peter , Falloon Peter , Jenkinson David , Powlson David 
Published: December 2004

AbstractEnhanced release of CO2 to the atmosphere from soil organic carbon as a result of increased temperatures may lead to a positive feedback between climate change and the carbon cycle, resulting in much higher CO2 levels and accelerated global warming. However, the magnitude of this effect is uncertain and critically dependent on how the decomposition of soil organic C (heterotrophic respiration) responds to changes in climate. Previous studies with the Hadley Centre's coupled climate–carbon cycle general circulation model (GCM) (HadCM3LC) used a simple, single‐pool soil carbon model to simulate the response. Here we present results from numerical simulations that use the more sophisticated ‘RothC’ multipool soil carbon model, driven with the same climate data.The results show strong similarities in the behaviour of the two models, although RothC tends to simulate slightly smaller changes in global soil carbon stocks for the same forcing. RothC simulates global soil carbon stocks decreasing by 54 Gt C by 2100 in a climate change simulation compared with an 80 Gt C decrease in HadCM3LC. The multipool carbon dynamics of RothC cause it to exhibit a slower magnitude of transient response to both increased organic carbon inputs and changes in climate. We conclude that the projection of a positive feedback between climate and carbon cycle is robust, but the magnitude of the feedback is dependent on the structure of the soil carbon model.