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Selected AbstractsAntimicrobial resistance in livestockJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2003B. Catry Antimicrobial resistance may become a major problem in veterinary medicine as a consequence of the intensive use and misuse of antimicrobial drugs. Related problems are now arising in human medicine, such as the appearance of multi-resistant food-borne pathogens. Product characteristics, dose, treatment interval and duration of treatment influence the selection pressure for antimicrobial drug resistance. There are theoretical, experimental and clinical indications that the emergence of de novo resistance in a pathogenic population can be prevented by minimizing the time that suboptimal drug levels are present in the infected tissue compartment. Until recently, attention has been focused on target pathogens. However, it should be kept in mind that when antimicrobial drugs are used in an individual, resistance selection mainly affects the normal body flora. In the long term, this is at least equally important as resistance selection in the target pathogens, as the horizontal transfer of resistance genes converts almost all pathogenic bacteria into potential recipients for antimicrobial resistance. Other factors contributing to the epidemiology of antimicrobial resistance are the localization and size of the microbial population, and the age, immunity and contact intensity of the host. In livestock, dynamic herd-related resistance patterns have been observed in different animal species. [source] The effect of social networks and social support on common mental disorders following specific life eventsACTA PSYCHIATRICA SCANDINAVICA, Issue 2 2010P. K. Maulik Maulik PK, Eaton WW, Bradshaw CP. The effect of social networks and social support on common mental disorders following specific life events. Objective:, This study examined the association between life events and common mental disorders while accounting for social networks and social supports. Method:, Participants included 1920 adults in the Baltimore Epidemiologic Catchment Area Cohort who were interviewed in 1993,1996, of whom 1071 were re-interviewed in 2004,2005. Generalized estimating equations were used to analyze the data. Results:, Social support from friends, spouse or relatives was associated with significantly reduced odds of panic disorder and psychological distress, after experiencing specific life events. Social networks or social support had no significant stress-buffering effect. Social networks and social support had almost no direct or buffering effect on major depressive disorder, and no effect on generalized anxiety disorder and alcohol abuse or dependence disorder. Conclusion:, The significant association between social support and psychological distress, rather than diagnosable mental disorders, highlights the importance of social support, especially when the severity of a mental health related problem is low. [source] Choosing the parameters of multiple-repetition strategies,EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 3 2007Thijs Veugen The class of multiple-repetition strategies is known to achieve capacity for specific discrete memoryless channels with noiseless feedback. We show, given an arbitrary discrete memoryless channel with noiseless feedback, that the repetition parameters should be chosen close to the self information of a transmission error to maximise the transmission rate. Furthermore, it is indicated how close the channel capacity can be approached in the general case. Finally, we compare some results on a related problem: the capacity of a discrete noiseless channel with constraints on the input symbols. Copyright © 2006 AEIT [source] A tabu search procedure for coordinating production, inventory and distribution routing problemsINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 2 2010André Luís Shiguemoto Abstract This paper addresses the problem of optimally coordinating a production-distribution system over a multi-period finite horizon, where a facility production produces several items that are distributed to a set of customers by a fleet of homogeneous vehicles. The demand for each item at each customer is known over the horizon. The production planning determines how much to produce of each item in every period, while the distribution planning defines when customers should be visited, the amount of each item that should be delivered to customers and the vehicle routes. The objective is to minimize the sum of production and inventory costs at the facility, inventory costs at the customers and distribution costs. We also consider a related problem of inventory routing, where a supplier receives or produces known quantities of items in each period and has to solve the distribution problem. We propose a tabu search procedure for solving such problems, and this approach is compared with vendor managed policies proposed in the literature, in which the facility knows the inventory levels of the customers and determines the replenishment policies. [source] Taking Pressure Off Families: Child-Care Subsidies Lessen Mothers' Work-Hour ProblemsJOURNAL OF MARRIAGE AND FAMILY, Issue 1 2006Julie E. Press We use the Philadelphia Survey of Child Care and Work to model the effect of child-care subsidies and other ecological demands and resources on the work hour, shift, and overtime problems of 191 low-income urban mothers. Comparing subsidy applicants who do and do not receive cash payments for child care, we find that mothers who receive subsidies are 21% less likely to experience at least one work hour,related problem on the job. Our results suggest that child-care subsidies do more than allow women to enter the labor force. Subsidies help make it easier for mothers in low-wage labor both to comply with employer demands for additional work hours and to earn the needed wages that accompany them. [source] Planning and Optimization of a Numerical Control Machine in a Multiple Response CaseQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 5 2006Rossella Berni Abstract This paper focuses on a specific case of experimental planning and optimization in a multiresponse case. Particularly, our attention is dedicated to a numerical control machine and our final goal is to improve this machine's measurement accuracy for a general dental implant. This work substantially aims at addressing two issues: the optimization methods in the presence of more response variables and the related problem of weighting according to the actual importance of these variables. About simultaneous optimization, we suggest an improvement by a new function which takes care of location and dispersion effects. Copyright © 2006 John Wiley & Sons, Ltd. [source] Sensitivity Analysis for Principal Stratum Direct Effects, with an Application to a Study of Physical Activity and Coronary Heart DiseaseBIOMETRICS, Issue 2 2009Arvid Sjölander Summary In many studies, the aim is to learn about the direct exposure effect, that is, the effect not mediated through an intermediate variable. For example, in circulation disease studies it may be of interest to assess whether a suitable level of physical activity can prevent disease, even if it fails to prevent obesity. It is well known that stratification on the intermediate may introduce a so-called posttreatment selection bias. To handle this problem, we use the framework of principal stratification (Frangakis and Rubin, 2002, Biometrics58, 21,29) to define a causally relevant estimand,the principal stratum direct effect (PSDE). The PSDE is not identified in our setting. We propose a method of sensitivity analysis that yields a range of plausible values for the causal estimand. We compare our work to similar methods proposed in the literature for handling the related problem of "truncation by death." [source] Language development and fragile X syndrome: Profiles, syndrome-specificity, and within-syndrome differencesDEVELOPMENTAL DISABILITIES RESEARCH REVIEW, Issue 1 2007Leonard Abbeduto Abstract Fragile X syndrome (FXS) is the leading inherited cause of mental retardation. In this article, we review what is known about the language and related problems of individuals with FXS. In doing so, we focus on the syndrome-specific features of the language phenotype and on the organismic (i.e., genetic and individual neurocognitive and behavioral) and environmental factors associated with within-syndrome variation in the phenotype. We also briefly review those aspects of the behavioral phenotype of FXS that are relevant for understanding syndrome-specific features of, and within-syndrome variability in, language. The review includes summaries of research on the prelinguistic foundations for language development and on each of the major components of language (i.e., vocabulary, morphosyntax, and pragmatics). Throughout the review, we point out implications of existing research for intervention as well as directions for future research. © 2007 Wiley-Liss, Inc. MRDD Research Reviews 2007;13:36,46. [source] What is Frege's Julius Caesar Problem?DIALECTICA, Issue 3 2003Dirk Greimann This paper aims to determine what kind of problem Frege's famous "Julius Caesar problem" is. whether it is to be understood as the metaphysical problem of determining what kind of things abstract objects like numbers or value-courses are, or as the epistemological problem of providing a means of recognizing these objects as the same again, or as the logical problem of providing abstract sortal concepts with a sharp delimitation in order to fulfill the law of excluded middle, or as the semantic problem of fixing the referents of the corresponding abstract singular terms. It is argued that, for Frege, the Caesar problem is a bundle of related problems of which the semantic problem is the most basic one. [source] Trends in morphine prescriptions, illicit morphine use and associated harms among regular injecting drug users in AustraliaDRUG AND ALCOHOL REVIEW, Issue 5 2006LOUISA DEGENHARDT Abstract This paper examines population trends in morphine prescriptions in Australia, and contrasts them with findings from annual surveys with regular injecting drug users (IDU). Data on morphine prescriptions from 1995 to 2003 were obtained from the Drug Monitoring System (DRUMS) run by the Australian Government Department of Health and Ageing. Data collected from regular IDU as part of the Australian Illicit Drug Reporting System (IDRS) were analysed (2001,2004). The rate of morphine prescription per person aged 15,54 years increased by 89% across Australia between 1995 and 2003 (from 46.3 to 85.9 mg per person). Almost half (46%) of IDU surveyed in 2004 reported illicit morphine use, with the highest rates in jurisdictions where heroin was less available. Recent morphine injectors were significantly more likely to be male, unemployed, out of treatment and homeless in comparison to IDU who had not injected morphine. They were also more likely to have injected other pharmaceutical drugs and to report injection related problems. Among those who had injected morphine recently, the most commonly reported injecting harms were morphine dependence (38%), difficulty finding veins into which to inject (36%) and scarring or bruising (27%). Morphine use and injection is a common practice among regular IDU in Australia. In some cases, morphine may be a substitute for illicit heroin; in others, it may be being used to treat heroin dependence where other pharmacotherapies, such as methadone and buprenorphine, are perceived as being unavailable or undesirable by IDU. Morphine injection appears to be associated with polydrug use, and with it, a range of problems related to drug injection. Further research is required to monitor and reduce morphine diversion and related harms by such polydrug injectors. [source] From scrubland to vintage wine: Australia's response to substance-related problems in the last 40 years,DRUG AND ALCOHOL REVIEW, Issue 3 2003FAChAM (Hon), FAFPHM, FRACP, FRCPC, Professor JAMES G. RANKIN MB Abstract Over the last 40 years Australia's response to substance-related problems compared with most western nations has been outstandingly good. Since the 1960s concerns about problems of substance use have expanded from a focus on alcohol to include tobacco and a wide range of other licit as well as illicit psychoactive substances. During this period there have been major advances in our knowledge and understanding of substance-related problems and effective methods of prevention, intervention and treatment. In parallel has been the development of a large number of non-government, government and professional organizations concerned with problems of substance use. These groups, individually and collectively, have contributed to the development of policies, plans, resources and programmes to prevent and minimize substance-related harm. Although significant progress in these endeavours took place between 1960 and 1986, there has been accelerated growth since and largely as a result of the establishment of the National Campaign Against Drug Abuse in 1986 and the ensuing National Drug Strategy and the Illicit Drug Strategy. However, much of this more recent success was possible because of the existence of the organizations, networks and infrastructures established in the earlier period and the Nation's general health, social and educational programmes. These initiatives have been associated with reductions in alcohol and tobacco use and related problems and evidence of reductions in some problem areas associated with illicit drug use. Despite these gains, there have been areas of failure and missed opportunities. Finally, it is critical to ensure that past achievements and opportunities for continued successful initiatives are not undermined by identifiable impediments and risks that could imperil the philosophy, goals, infrastructure and programmes that form the basis for Australia's success to date. [source] Computer-delivered interventions for alcohol and tobacco use: a meta-analysisADDICTION, Issue 8 2010Sally Rooke ABSTRACT Aims To quantify the overall effectiveness of computer-delivered interventions for alcohol and tobacco use. Methods Meta-analysis of 42 effect sizes from randomized controlled trials, based on the responses of 10 632 individuals. Results The weighted average effect size (d) was 0.20, P < 0.001. While lower effect sizes were associated with studies addressing tobacco use (d = 0.14) this may well reflect differences in the types of outcome measure used. Effect sizes did not vary significantly as a function of treatment location, inclusion of entertaining elements, provision of normative feedback, availability of a discussion feature, number of treatment sessions, emphasis on relapse prevention, level of therapist involvement or follow-up period. Conclusion Findings of the meta-analysis suggest that minimal contact computer-delivered treatments that can be accessed via the internet may represent a cost-effective means of treating uncomplicated substance use and related problems. [source] A dose,response perspective on college drinking and related problemsADDICTION, Issue 2 2010Paul J. Gruenewald ABSTRACT Aims In order to examine the degree to which heavy drinking contributes to risks for problems among college drinkers this paper develops and tests a dose,response model of alcohol use that relates frequencies of drinking specific quantities of alcohol to the incidence of drinking problems. Methods A mathematical model was developed that enabled estimation of dose,response relationships between drinking quantities and drinking problems using self-report data from 8698 college drinkers across 14 campuses in California, USA. The model assumes that drinking risks are a direct monotone function of the amount consumed per day and additive across drinking days. Drinking problems accumulate across drinking occasions and are the basis for cumulative reports of drinking problems reported by college drinkers. Results Statistical analyses using the model showed that drinking problems were related to every drinking level, but increased fivefold at three drinks and more gradually thereafter. Problems were associated most strongly with occasions on which three drinks were consumed, and more than half of all reported problems were related to occasions on which four or fewer drinks were consumed. There were some important differences in dose,responsiveness between men and women and between different groups of ,light', ,moderate' and ,heavier' drinkers. Conclusion Many problems among college students are associated with drinking relatively small amounts of alcohol (two to four drinks). Programs to reduce college drinking problems should emphasize risks associated with low drinking levels. [source] Alcohol outlet density and university student drinking: a national studyADDICTION, Issue 7 2008Kypros Kypri ABSTRACT Aims To examine the geographic density of alcohol outlets and associations with drinking levels and related problems among university students. Design Cross-sectional survey study using geospatial data, with campus-level and individual-level analyses. Participants A total of 2550 students (mean age 20.2, 60% women) at six university campuses in New Zealand (63% response). Measurements Counts of alcohol outlets within 3 km of each campus were tested for their non-parametric correlation with aggregated campus drinking levels and related problems. Generalized estimating equations were used to model the relation between outlet counts within 1 km and 3 km of student residences and individual drinking levels/problems, with control for gender, age, ethnicity and high school binge drinking frequency, and adjustment for campus-level clustering. Findings Correlations for campus-level data were 0.77 (P = 0.07) for drinking and personal problems, and 0.31 (P = 0.54) for second-hand effects. There were consistent significant associations of both on- and off-licence outlet densities with all outcomes in student-level adjusted models. Effects were largest for 1 km densities and off-licence outlets. Conclusions There are positive associations between alcohol outlet density and individual drinking and related problems. Associations remain after controlling for demographic variables and pre-university drinking, i.e. the associations are unlikely to be due to self-selection effects. Increasing alcohol outlet density, and particularly off-licences, may increase alcohol-related harm among university students. [source] On the use of generalized linear models for interpreting climate variabilityENVIRONMETRICS, Issue 7 2005Richard E. Chandler Abstract Many topical questions in climate research can be reduced to either of two related problems: understanding how various different components of the climate system affect each other, and quantifying changes in the system. This article aims to justify the addition of generalized linear models to the climatologist's toolkit, by demonstrating that they offer an intuitive and flexible approach to such problems. In particular, we provide some suggestions as to how ,typical' climatological data structures may be represented within the GLM framework. Recurring themes include methods for space,time data and the need to cope with large datasets. The ideas are illustrated using a dataset of monthly U.S. temperatures. Copyright © 2005 John Wiley & Sons, Ltd. [source] A survey of equine abortion, stillbirth and neonatal death in the UK from 1988 to 1997EQUINE VETERINARY JOURNAL, Issue 5 2003K. C. SMITH Summary Reasons for performing study: A detailed review of laboratory records for equine abortion is fundamental in establishing current disease trends and suggesting problems important for further research. Objectives: To review the causes of abortion and neonatal death in equine diagnostic submissions to the Animal Health Trust over a 10 year period. Methods: The diagnoses in 1252 equine fetuses and neonatal foals were reviewed and analysed into categories. Results: Problems associated with the umbilical cord, comprising umbilical cord torsion and the long cord/cervical pole ischaemia disorder, were the most common diagnoses (38.8%: 35.7% umbilical cord torsion and 3.1% long cord/cervical pole ischaemia disorder). Other noninfective causes of abortion or neonatal death included twinning (6.0%), intrapartum stillbirth (13.7%) and placentitis, associated with infection (9.8%). E. coli and Streptococcus zooepidemicus were the most common bacteria isolated. Neonatal infections not associated with placentitis accounted for 3.2% of incidents; and infections with EHV-1 or EHV-4 for 6.5%. Conclusions: Definitive diagnosis of equine abortion is possible in the majority of cases where the whole fetus and placenta are submitted for examination. Potential relevance: Given the high incidence of umbilical cord torsion and related problems as causes of abortion in UK broodmares, more research on factors determining umbilical cord length and risk of torsion is essential. [source] Crayfish effects on seeds and seedlings: identification and quantification of damageFRESHWATER BIOLOGY, Issue 4 2005PEDRO M. ANASTÁCIO Summary 1. The red-swamp crayfish (Procambarus clarkii) is an invasive species and an important pest of wet-seeded rice fields (Oryza sativa) in California (U.S.A.) and in Portugal. Our work quantifies rice consumption and non-consumptive destruction and identifies the types of direct damage inflicted by crayfish. 2. The following fractions were quantified in the presence and absence of crayfish and at 3 and 6 days of rice development: (1) non-germinated seeds, (2) damaged seeds, (3) seeds not recovered, (4) intact rooted seedlings, (5) rooted damaged seedlings, (6) uprooted intact seedlings, (7) uprooted damaged seedlings. 3. Coarse particulate organic matter (CPOM) fragments produced during the feeding process were <2% of the material removed by crayfish. 4. Damage occurred with or without uprooting of the plants, but the incidence of uprooting without consumption was low (1.4%). 5. Consumption of recently developed parts of the rice plant was the main cause of damage and the observed effect was stronger on 6-day-old than on 3-day-old seedlings. Seedlings were more affected by crayfish than were seeds. 6. Crayfish affected the majority of seeds and seedlings available although consumption was low: 0.015 g dry weight (DW) rice g,1 wet weight (WW) crayfish per 12 h at 3 days and 0.063 g DW rice g,1 WW crayfish per 12 h at 6 days. 7. Our results are important for the mitigation of crayfish related problems in rice fields and for understanding the mechanisms of crayfish-macrophyte interactions. [source] Clubs, Spades, Diamonds and Disadvantage: the Geography of Electronic Gaming Machines in MelbourneGEOGRAPHICAL RESEARCH, Issue 1 2001D.C. Marshall Opportunities to gamble, particularly on electronic gaming machines (EGMs) have been rapidly increasing in Australia during the 1990s. The increase in expenditure on gambling and the related problems have subsequently become a growing concern, particularly in relation to disadvantaged sectors of the population. Given this, the development of a geography of gambling is an important step in understanding the implications of this rapidly expanding industry. This paper addresses this issue at two distinct geographical scales in metropolitan Melbourne and considers the distribution of EGMs in relation to levels of economic well-being. Findings suggest that patterns evident at the wider Melbourne scale of greater concentration of EGMs in less advantaged regions are also reflected at a local level. These findings are related to the wider issues of accessibility to gambling facilities and problem gambling. [source] Free tissue transfer and local flap complications in anterior and anterolateral skull base surgeryHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 10 2002Jason A. Heth MD Abstract Background Advances in reconstructive techniques over the past two decades have allowed the resection of more extensive skull base tumors than had previously been possible. Despite this progress, complications related to these cases remain a concern. Methods Univariate and multivariate analyses were used to determine the relationship of host, tumor, defect, treatment, and reconstructive variables to wound and systemic complications after anterior and anterolateral skull base resections. The study included 67 patients receiving local flap (LF) or free tissue transfer (FTT) reconstructions during an 8-year period. Results Overall, 28% of patients had a major wound complication, and 19% had a major systemic complication. LF and FTT flaps had similar rates of wound complications. LF reconstructions were associated with late wound breakdown problems, and FTT flap complications were primarily acute surgery,related problems. Conclusions The surgical reconstruction of skull base defects should be planned on the basis of the ability of the technique to attain safe closure and maintain integrity after radiation therapy. © 2002 Wiley Periodicals, Inc. Head Neck 24: 00,00, 2002 [source] Hybrid and enhanced finite element methods for problems of soil consolidationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2007X. X. Zhou Abstract Hybrid and enhanced finite element methods with bi-linear interpolations for both the solid displacements and the pore fluid pressures are derived based on mixed variational principles for problems of elastic soil consolidation. Both plane strain and axisymmetric problems are studied. It is found that by choosing appropriate interpolation of enhanced strains in the enhanced method, and by choosing appropriate interpolations of strains, effective stresses and enhanced strains in the hybrid method, the oscillations of nodal pore pressures can be eliminated. Several numerical examples demonstrating the capability and performance of the enhanced and hybrid finite element methods are presented. It is also shown that for some situations, such as problems involving high Poisson's ratio and in other related problems where bending effects are evident, the performance of the enhanced and hybrid methods are superior to that of the conventional displacement-based method. The results from the hybrid method are better than those from the enhanced method for some situations, such as problems in which soil permeability is variable or discontinuous within elements. Since all the element parameters except the nodal displacements and nodal pore pressures are assumed in the element level and can be eliminated by static condensation, the implementations of the enhanced method and the hybrid method are basically the same as the conventional displacement-based finite element method. The present enhanced method and hybrid method can be easily extended to non-linear consolidation problems. Copyright © 2006 John Wiley & Sons, Ltd. [source] MR linear contact detection algorithmINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2006A. Munjiza Abstract Large-scale discrete element simulations, as well as a whole range of related problems, involve contact of a large number of separate bodies and an efficient and robust contact detection algorithm is necessary. There has been a number of contact detection algorithms with total detection time proportional to N ln(N) (where N is the total number of separate bodies) reported in the past. In more recent years algorithms with total CPU time proportional to N have been developed. In this work, a novel contact detection algorithm with total detection time proportional to N is proposed. The performance of the algorithm is not influenced by packing density, while memory requirements are insignificant. The algorithm is applicable to systems comprising bodies of a similar size. The algorithm is named MR (Munjiza,Rougier: Munjiza devised the algorithm, Rougier implemented it). In the second part of the paper the algorithm is extended to particles of different sizes. The new algorithm is called MMR (multi-step MR) algorithm. Copyright © 2005 John Wiley & Sons, Ltd. [source] Common-refinement-based data transfer between non-matching meshes in multiphysics simulationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2004Xiangmin Jiao Abstract In multiphysics simulations using a partitioned approach, each physics component solves on its own mesh, and the interfaces between these meshes are in general non-matching. Simulation data (e.g. jump conditions) must be exchanged across the interface meshes between physics components. It is highly desirable for such data transfers to be both numerically accurate and physically conservative. This paper presents accurate, conservative, and efficient data transfer algorithms utilizing a common refinement of two non-matching surface meshes. Our methods minimize errors in a certain norm while achieving strict conservation. Some traditional methods for data transfer and related problems are also reviewed and compared with our methods. Numerical results demonstrate significant advantages of common-refinement based methods, especially for repeated transfers. While the comparisons are performed with matching geometries, this paper also addresses additional complexities associated with non-matching surface meshes and presents some experimental results from 3-D simulations using our methods. Copyright © 2004 John Wiley & Sons, Ltd. [source] Special issue on cutting, packing and related problemsINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 6 2009Reinaldo Morabito No abstract is available for this article. [source] Bayesian approaches in evolutionary quantitative geneticsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2008R. B. O'HARA Abstract The study of evolutionary quantitative genetics has been advanced by the use of methods developed in animal and plant breeding. These methods have proved to be very useful, but they have some shortcomings when used in the study of wild populations and evolutionary questions. Problems arise from the small size of data sets typical of evolutionary studies, and the additional complexity of the questions asked by evolutionary biologists. Here, we advocate the use of Bayesian methods to overcome these and related problems. Bayesian methods naturally allow errors in parameter estimates to propagate through a model and can also be written as a graphical model, giving them an inherent flexibility. As packages for fitting Bayesian animal models are developed, we expect the application of Bayesian methods to evolutionary quantitative genetics to grow, particularly as genomic information becomes more and more associated with environmental data. [source] Developmental Trajectories of Impulsivity and Their Association With Alcohol Use and Related Outcomes During Emerging and Young Adulthood IALCOHOLISM, Issue 8 2010Andrew K. Littlefield Background:, Research has documented normative patterns of personality change during emerging and young adulthood that reflect decreases in traits associated with substance use, such as impulsivity. However, evidence suggests variability in these developmental changes. Methods:, This study examined trajectories of impulsivity and their association with substance use and related problems from ages 18 to 35. Analyses were based on data collected from a cohort of college students (N = 489), at high and low risk for AUDs, first assessed as freshmen at a large, public university. Results:, Mixture modeling identified five trajectory groups that differed in baseline levels of impulsivity and developmental patterns of change. Notably, the trajectory group that exhibited the sharpest declines in impulsivity tended to display accelerated decreases in alcohol involvement from ages 18 to 25 compared to the other impulsivity groups. Conclusion:, Findings highlight the developmental nature of impulsivity across emerging and young adulthood and provide an empirical framework to identify key covariates of individual changes of impulsivity. [source] AIRBORNE ALGAE: THEIR PRESENT STATUS AND RELEVANCE,JOURNAL OF PHYCOLOGY, Issue 4 2007Naveen Kumar Sharma Ongoing climatic changes coupled with various natural processes and the outcomes of human activities are not only loading the atmosphere with diverse kinds of biological particles but also changing their prevalence and spatial distribution. Despite having considerable ecological and economic significance, including their possible impact on human health, airborne algae are the least-studied organisms in both aerobiological and phycological studies. The present review has been written to bring together all available information, including a brief survey of the literature, the ecology of airborne algae, mechanisms involved in their aerosolization, the role of environmental factors in shaping the structure and composition of aero-algal flora, and other significant information associated with airborne algae. This review provides information on methodological approaches and related problems, along with suggestions for areas of future research on airborne algae. [source] Transfer of algebraic and graphical thinking between mathematics and chemistryJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 2 2008Marietjie Potgieter Students in undergraduate chemistry courses find, as a rule, topics with a strong mathematical basis difficult to master. In this study we investigate whether such mathematically related problems are due to deficiencies in their mathematics foundation or due to the complexity introduced by transfer of mathematics to a new scientific domain. In the investigation we exposed a group of students to a chemistry instrument based on the Nernst equation in electrochemistry, and an equivalent group of students to a similar mathematics instrument in which the questions were stripped of all chemistry context. Both tests contained items requiring algebraic as well as graphical skills. Students experienced few problems with the algebraic questions in both the chemistry and mathematics tests. Their graphical construction and interpretation skills, on the other hand, are inadequate, as can be seen from the poor performance in both the mathematics and the chemistry results of the graphical question. Our conclusion is that the problem seems to lie at the mathematics side and is not due to the transfer of mathematics to an application. © Wiley Periodicals, Inc. J Res Sci Teach 45: 197,218, 2008. [source] The incidence of land tenure insecurity in Southern Africa: Policy implications for sustainable developmentNATURAL RESOURCES FORUM, Issue 3 2007Gladys Mutangadura Abstract The study presented in this article used a combination of key informant interviews and a review and synthesis of existing country level literature to identify the major sources of land tenure insecurity in six Southern African countries: Botswana, Lesotho, Malawi, Mozambique, South Africa, and Zambia. Findings reveal that the main causes of land tenure insecurity experienced in Southern Africa include lack of land rights of minority groups, unclear or overlapping land rights, overcrowding, land alienation into leasehold, insecurity of farm workers and farm labour tenants, inappropriate and exploitative administrative practices, land encroachment and illegal settlers and limited women's land rights. The article presents a summary of land tenure security related initiatives that the study countries have or are in the process of adopting. Analysis of these initiatives shows that tenure reforms have focused on changing the law and rules but little has been done to translate new laws into implementable programs; capacity building; prioritization of resources to support tenure reform; provision of complementary policies and incentives; addressing HIV/AIDS-land tenure related problems; and monitoring and evaluation. The paper contends that these policy issues should be addressed in order to ensure realization of land tenure security for all. [source] Approximation schemes for ordered vector packing problemsNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 1 2003Alberto Caprara In this paper we deal with the d -dimensional vector packing problem, which is a generalization of the classical bin packing problem in which each item has d distinct weights and each bin has d corresponding capacities. We address the case in which the vectors of weights associated with the items are totally ordered, i.e., given any two weight vectors ai, aj, either ai is componentwise not smaller than aj or aj is componentwise not smaller than ai. An asymptotic polynomial-time approximation scheme is constructed for this case. As a corollary, we also obtain such a scheme for the bin packing problem with cardinality constraint, whose existence was an open question to the best of our knowledge. We also extend the result to instances with constant Dilworth number, i.e., instances where the set of items can be partitioned into a constant number of totally ordered subsets. We use ideas from classical and recent approximation schemes for related problems, as well as a nontrivial procedure to round an LP solution associated with the packing of the small items. © 2002 Wiley Periodicals, Inc. Naval Research Logistics, 2003 [source] Diabetes and the enteric nervous systemNEUROGASTROENTEROLOGY & MOTILITY, Issue 12 2007B. Chandrasekharan Abstract, Diabetes is associated with several changes in gastrointestinal (GI) motility and associated symptoms such as nausea, bloating, abdominal pain, diarrhoea and constipation. The pathogenesis of altered GI functions in diabetes is multifactorial and the role of the enteric nervous system (ENS) in this respect has gained significant importance. In this review, we summarize the research carried out on diabetes-related changes in the ENS. Changes in the inhibitory and excitatory enteric neurons are described highlighting the role of loss of inhibitory neurons in early diabetic enteric neuropathy. The functional consequences of these neuronal changes result in altered gastric emptying, diarrhoea or constipation. Diabetes can also affect GI motility through changes in intestinal smooth muscle or alterations in extrinsic neuronal control. Hyperglycaemia and oxidative stress play an important role in the pathophysiology of these ENS changes. Antioxidants to prevent or treat diabetic GI motility problems have therapeutic potential. Recent research on the nerve,immune interactions demonstrates inflammation-associated neurodegeneration which can lead to motility related problems in diabetes. [source] | ||||||||||||||||||||||||||||