Home About us Contact
|
Home About us Contact | ||
|
|
||
Successive Periods (successive + period)
Selected AbstractsPressure gradient force, atmospheric circulation and climate in western Europe (1899,2002)INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 15 2007Pierre P. Kastendeuch Abstract One mission of synoptic climatology is to quantify the link between atmospheric circulation and surface environment. The pressure gradient force (PGF) is used as a multiple index to summarize the monthly atmospheric circulation for a site in western Europe (5°E and 50°N). The study of the temporal evolution of the PGF components (direction, magnitude, X and Y components) was carried out for the period 1899,2002. The results reflect the variability in atmospheric circulation and reveal some trends. The magnitude of the PGF is particularly affected by several successive periods where the strength of the atmospheric flow was lower (negative trend) or higher (positive trend) than normal. During the last decades of the twentieth century the atmospheric flow appears stronger than before (positive trend), except in summer. As the direction of the PGF can be related to the trajectory of the flow via the Buys,Ballot law, its anomalies are directly related to anomalies in the advection of air masses. No definite trend can be detected for this variable. However, it seems that the northerly flow becomes rare in winter. The relevance of the PGF is also examined with regard to the evolution of monthly temperatures and precipitations via some series of multiple regressions. The best results are obtained for the precipitations, with an explained variance lying between 47 and 73% (respectively in May and February). For temperatures, the explained variance oscillates between 34 and 73% (in September and January). The fact that the meridional and zonal components of the PGF, and the absolute pressure at the site are explicitly taken into account, ensures a good quantification of the atmospheric circulation ,anomalies', that are largely responsible for the annual, seasonal or monthly singularities of temperature and precipitation over western Europe. Copyright © 2007 Royal Meteorological Society [source] Real-Time Feedback on Rater Drift in Constructed-Response Items: An Example From the Golden State ExaminationJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 2 2001Machteld Hoskens In this study, patterns of variation in severities of a group of raters over time or so-called "rater drift" was examined when raters scored an essay written under examination conditions. At the same time feedback was given to rater leaders (called "table leaders") who then interpreted the feedback and reported to the raters. Rater severities in five successive periods were estimated using a modified linear logistic test model (LLTM, Fischer, 1973) approach. It was found that the raters did indeed drift towards the mean, but a planned comparision of the feedback with a control condition was not successful; it was believed that this was due to contamination at the table leader level. A series of models was also estimated designed to detect other types of rater effects beyond severity: a tendency to use extreme scores, and tendency to prefer certain categories. The models for these effects were found to be showing significant improvement in fit, implying that these effects were indeed present, although they were difficult to detect in relatively short time periods. [source] Effect of cycles of feed deprivation on growth and food consumption of immature three-spined sticklebacks and European minnowsJOURNAL OF FISH BIOLOGY, Issue 1 2003L. Wu Individual juvenile three-spined sticklebacks Gasterosteus aculeatus and European minnow Phoxinus phoxinus, from sympatric populations, were subjected to four cycles of 1 week of food deprivation and 2 weeks of ad libitum feeding. Mean specific growth rate during the weeks of deprivation was negative and did not differ between species. The three-spined stickleback showed sufficient growth compensation to recover to the growth trajectory shown by control fish daily fed ad libitum. The compensation was generated by hyperphagia during the re-feeding periods, and in the last two periods of re-feeding, the gross growth efficiencies of deprived three-spined sticklebacks were greater than in control fish. The expression of the compensatory changes in growth and food consumption became clearer over the successive periods of re-feeding. The European minnow developed only a weak compensatory growth response and the mass trajectory of the deprived fish deviated more and more from the control trajectory. During re-feeding periods, there were no significant differences in food consumption or gross growth efficiency between control and deprived European minnows. The differences between the two species are discussed in terms of the possible costs of compensatory growth, the control of growth and differences in feeding biology. [source] Onset and relapse of psychiatric disorders following early breast cancer: a case,control studyPSYCHO-ONCOLOGY, Issue 10 2009Catherine Gandubert Abstract Objective: Our objective is to evaluate the mental status of primary early breast cancer survivors according to DSM-IV criteria, distinguishing new psychiatric diagnosis, which started after the cancer diagnosis from relapse. Methods: A comparative study of 144 breast cancer survivors and 125 women without previous history of cancer was carried out. Neuropsychiatric symptomatology was assessed retrospectively using standardized psychiatric examinations (Mini International Neuropsychiatric Interview, Watson's Post-Traumatic Stress Disorder Inventory) over three successive periods, ,before cancer' (from childhood to 3 years before the interview), ,around the cancer event' (the last 3 years including the time of diagnosis and treatment), and ,currently' (the last 2 weeks). Results: Increased rates of anxiety and mood disorders were observed following a diagnosis of breast cancer compared with controls (generalized anxiety disorder (GAD) and major depressive disorder (MDD); 10.4 vs 1.6% and 19.4 vs 8.8%, respectively). The cancer disease promoted the development of dysthymia (n=4 new cases/6 two-year prevalent cases) and PTSD (7/7) and the re-emergence of MDD (n=21 relapses/28 three-year prevalent cases) and GAD (10/15). No improvement in serious mood disorders such as MDD (16.0 vs 7.2%) and dysthymia (4.2 vs 0%) was reported at the time of interview, more than 1.75 years (median time) after the cancer surgery, the prevalence being 2,4 times greater in breast cancer survivors than in controls. Conclusion: Despite significant advances in treatment, a diagnosis of breast cancer is highly associated with various forms of psychopathology, regardless of psychiatric history, with symptoms persisting after treatment. These results may assist clinicians in planning mental healthcare for women with breast cancer. Copyright © 2009 John Wiley & Sons, Ltd. [source] ON LABOUR DEMAND AND EQUILIBRIA OF THE FIRM,THE MANCHESTER SCHOOL, Issue 5 2005ROBERT L. VIENNEAU This note considers a linear programming formulation of the problem of the firm. A neoclassical non-increasing labour demand function is derived from the solution of the linear program. Only a set of measure zero on this function, one or two points in the examples examined, provides equilibria of the representative firm. Equilibria of the representative firm are characterized by decisions of its managers that allow the same decisions to be made in successive periods. Hence, one can explain the quantity of labour that firms desire to hire either by a traditional neoclassical labour demand function or by equilibria of the firm, but generally not both. [source] Life-cycle phenology of some aquatic insects: implications for pond conservationAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2005Jérôme Cayrou Abstract 1.Life-cycles and growth patterns were determined for 21 dominant aquatic insect species in small permanent ponds in an arid, karstic region (SW France, site fr7300909 of the Natura 2000 conservation network). The species studied are widely distributed throughout Europe, but some life-cycle patterns are reported here for the first time. 2.The life-history patterns of the 21 species can be divided into five main types: (i) a semivoltine cycle spreading over 2 years; (ii) slow univoltine cycles; (iii) fast univoltine cycles; (iv) multivoltine life-cycles with a long winter generation and two or three summer generations per year; and (v) bivoltine life-cycles with two fast generations per year. Growth was either exponential over the whole developmental period for a given cohort, or divided into two or three successive periods during each of which the growth rate was fairly constant. 3.Biodiversity estimates strongly depend on the temporal and spatial scale over which observations are made. Ponds thus provide useful models to show how life-history patterns enable many temporally segregated populations to utilize small ecosystems. Conservation frameworks should therefore carefully consider the time-frame needed to survey ponds, as many species with fast cycles could be overlooked. The spatial scale needed to manage threatened habitats and thus preserve pond networks must be broadened, rather than attempting to target individual water bodies for particular management actions. Copyright © 2005 John Wiley & Sons, Ltd. [source] Trichostrongylid infections in sheep after rainfall during summer in southern AustraliaAUSTRALIAN VETERINARY JOURNAL, Issue 9 2002P NIVEN Objective To relate trichostrongylid infections acquired by sheep during summer to prevailing weather conditions. Procedure Groups of worm-free ,tracer' sheep were put onto pastures, previously contaminated with trichostrongylid eggs, for successive periods of 2 weeks from December to March. After grazing the sheep were housed for 6 weeks. Weekly worm egg counts and worm counts were used to estimate the numbers of worms acquired and related to weather conditions during the grazing period. Results No worm eggs were detected in the faeces of sheep that grazed at the end of January when only 7 mm of rainfall was recorded. At other times rainfall between 12 and 24 mm occurred and strongyle egg counts were generally either < 50 or > 150 eggs per g (epg). Mean counts of 1100 Ostertagia and Trichostrongylus adults gave rise to mean counts of about 350 epg whereas about 6000 Nematodirus spp were associated with mean egg counts of about 200 Nematodirus spp epg. Conclusions Rainfall events during summer determine the numbers of trichostrongylid larvae acquired by sheep in summer but further studies are necessary before the implications for strategic control programs in southern Australia can be fully assessed. [source] Applications of Extensions of Bivariate Rank Sum Statistics to the Crossover Design to Compare Two Treatments Through Four Sequence GroupsBIOMETRICS, Issue 3 2009Atsushi Kawaguchi Summary This article describes applications of extensions of bivariate rank sum statistics to the crossover design with four sequence groups for two treatments. A randomized clinical trial in ophthalmology provides motivating background for the discussion. The bilateral design for this study has four sequence groups T:T, T:P, P:T, and P:P, respectively, for T as test treatment or P as placebo in the corresponding order for the left and right eyes. This article describes how to use the average of the separate Wilcoxon rank sum statistics for the left and right eyes for the overall comparison between T and P with the correlation between the two eyes taken into account. An extension of this criterion with better sensitivity to potential differences between T and P through reduction of the applicable variance has discussion in terms of a conceptual model with constraints for within-side homogeneity of groups with the same treatment and between-side homogeneity of the differences between T and P. Goodness of fit for this model can have assessment with test statistics for its corresponding constraints. Simulation studies for the conceptual model confirm better power for the extended test statistic with its full invocation than other criteria without this property. The methods summarized here are illustrated for the motivating clinical trial in ophthalmology, but they are applicable to other situations with the crossover design with four sequence groups for either two locations for two treatments at the same time for a patient or two successive periods for the assigned treatments for a recurrent disorder. This article also notes that the methods based on its conceptual model can have unsatisfactory power for departures from that model where the difference between T and P via the T:T and P:P groups is not similar to that via the T:P and P:T groups, as might occur when T has a systemic effect in a bilateral trial. For this situation, more robust test statistics have identification, but there is recognition that the parallel groups design with only the T:T and P:P groups may be more useful than the bilateral design with four sequence groups. [source] An updated history of the Teratology SocietyBIRTH DEFECTS RESEARCH, Issue 5 2010Thomas H. Shepard BACKGROUND: The 49-year history of the Teratology Society is reviewed. An abbreviated history is outlined in table form, with listings of the Warkany Lectures, the Continuing Education Courses, and officers of the society. The original article was updated to include the years 2000 to 2010. METHODS: A year-by-year description of the events is given, including the scientific and social content of the annual meetings and changes in the business of the society, in many cases using comments from the past presidents. The valuable and unique diversity of the members is discussed and illustrated, presenting the disciplines and main research areas of the presidents. The number of submitted abstracts and the various categories are tabulated, averaging the number and type over successive periods. A significant increase in the number of abstracts dealing with epidemiology and developmental biology is evident. The society's development is compared to that of a human, and the question was asked by Shephard et al. (2000): Have we reached the maturational stage of old age or senescence, or is the society still maturing gracefully? This question needs further discussion by all the members. By 2010, many positive changes are happening to revitalize the society. RESULTS: During the past 50 years, we have developed the scientific basis to prevent birth defects caused by rubella, alcoholism, and folate deficiency, as well as other prenatal exposures. We are now taking advantage of advances in many fields to begin shaping the Teratology Society of the 21st century. CONCLUSIONS: We must now engage in political battles to obtain the resources needed to conduct further research and to implement prevention programs, as well as to provide care and rehabilitation for persons with birth defects. Birth Defects Research (Part A), 2010. © 2010 Wiley-Liss, Inc. [source] | ||||||||||||||||