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Shortage
Kinds of Shortage Selected AbstractsDEMOGRAPHIC SHIFT AND PROJECTED LABOUR SHORTAGE IN CHINAECONOMIC PAPERS: A JOURNAL OF APPLIED ECONOMICS AND POLICY, Issue 3 2007INGRID NIELSEN As a result of China's family planning policy of ,raising population quality and controlling population size' initiated in the late 1970s, China has accomplished a population transition from high birth rate, low mortality rate and high population growth to low birth rate, low mortality rate and low population growth within a remarkably short timeframe. Along with this population transition, however, comes a shift in population age structure, with a rapid increase in the proportion of elderly people. This paper explores the implications of China's demographic shift for labour supply and suggests policy changes to target an emerging labour shortage. [source] A SHORTAGE OF MEDICAL DOCTORS TO MEET THE CHALLENGES OF A GROWING ADDICTION PROBLEM IN LOW AND MIDDLE INCOME COUNTRIES: THE CASE IN MEXICOADDICTION, Issue 2 2009MARIA ELENA MEDINA-MORA No abstract is available for this article. [source] THE SHORTAGE OF NURSES IN GREECEINTERNATIONAL JOURNAL OF NURSING PRACTICE, Issue 1 2000Article first published online: 24 DEC 200 No abstract is available for this article. [source] CIRCULATION OF PRIVATE NOTES DURING A CURRENCY SHORTAGE,THE MANCHESTER SCHOOL, Issue 4 2009XAVIER CUADRAS-MORATÓ In this paper we present a version of the search theoretical model of money that captures two phenomena that have characterized several episodes of monetary history: currency shortages and the circulation of privately issued notes. As usual in these models, the media of exchange are determined as part of the equilibrium. We characterize all the different equilibria and specify the conditions under which there is a currency shortage and/or privately issued notes are used as means of payment. There always exists an equilibrium in which notes circulate, either alone or together with coins and, hence, credit is a self-fulfilling phenomenon. [source] Wage policy in the health care sector: a panel data analysis of nurses' labour supplyHEALTH ECONOMICS, Issue 9 2003Jan Erik Askildsen Abstract Shortage of nurses is a problem in several countries. It is an unsettled question whether increasing wages constitute a viable policy for extracting more labour supply from nurses. In this paper we use a unique matched panel data set of Norwegian nurses covering the period 1993,1998 to estimate wage elasticities. The data set includes detailed information on 19 638 individuals over 6 years totalling 69 122 observations. The estimated wage elasticity after controlling for individual heterogeneity, sample selection and instrumenting for possible endogeneity is 0.21. Individual and institutional features are statistically significant and important for working hours. Contractual arrangements as represented by shift work are also important for hours of work, and omitting information about this common phenomenon will underestimate the wage effect. Copyright © 2003 John Wiley & Sons, Ltd. [source] Shortage of nurses means shortage of nurse scientistsJOURNAL OF ADVANCED NURSING, Issue 2 2005Afaf I. Meleis PhD DrPS FAAN No abstract is available for this article. [source] Effects of Water Shortage and Air Temperature on Seed Yield and Seed Performance of Lucerne (Medicago sativa L.) in a Mediterranean EnvironmentJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2009A. J. Karamanos Abstract Seed production and performance of lucerne is characterized by fluctuating yields with often poor seed quality, and is dependent on environmental conditions, genetic characteristics and agronomic techniques applied during seed set, development, maturation and storage. A field experiment was carried out in two successive growing seasons at Kopais (southern Greece) to evaluate the effects of drought stress imposed by three irrigation treatments, and temperature during flowering and seed filling on lucerne seed yield and quality. Plant water status, expressed in terms of the water potential index (WPI), growth in leaf area and dry weight, seed yield and yield components, flowering and seed quality parameters were measured throughout the growing seasons. The adopted irrigation schemes produced a clear differentiation among treatments concerning their plant water status. Seed yield and leaf growth showed close positive correlations with WPI. An irrigation effect was also detected for the number of pods/plant, but not for the average weight of seeds/pod. Less negative values of WPI, and, especially, higher temperatures during flowering were also positively associated with a longer duration of flowering, as well as with higher total numbers of inflorescences. A very good description of the time course of seed germination was performed by fitting the Richards' function to the real data. By examining the germination parameters derived from this function it was found that final germination and germination rate were improved, while germination duration was shortened with more negative values of WPI. The effects of growing season and seeding period were occasionally equally or more important than irrigation effects. These results are also discussed in terms of their practical implications for seed producing lucerne crops. [source] Absence of transmission of potentially xenotic viruses in a prospective pig to primate islet xenotransplantation study,JOURNAL OF MEDICAL VIROLOGY, Issue 11 2008Olga Garkavenko Abstract Shortage of human donor organs for transplantation has prompted usage of animals as an alternative donor source. Pigs are the most acceptable candidate animals but issues of xenozoonoses remain. Despite careful monitoring of designated pathogen free pigs there is still a risk that their tissues may carry infectious agents. Thus xenotransplantation requires extensive pre-clinical study on safety of the graft especially for those viruses that are either potentially oncogenic and/or immunosuppressive, or can establish persistent infection. A prospective pig-to-primate islet xenotransplantation study was performed which includes monitoring for potentially xenotic viruses namely porcine endogenous retrovirus (PERV), porcine cytomegalovirus (PCMV), porcine lymphotropic herpesvirus (PLHV), and porcine circovirus (PCV) using both molecular diagnostic,PCR and RT-PCR and serology methods. There was no evidence of pig virus transmission into primate recipients. This preclinical study underlines the information concerning viral safety of islet cell xenograft in pig-to-primate xenotransplantation. J. Med. Virol. 80:2046,2052, 2008. © 2008 Wiley-Liss, Inc. [source] Labour Policy and Determinants of Employment and Wages in a Developing Economy with Labour ShortageLABOUR, Issue 2 2010Ibrahim Mohamed Abdalla Using data from a sample of 1,099 workers, this paper investigates the determinants of employment and wages for workers in the United Arab Emirates. The paper further examines the wage distribution and the decomposition of the wage gap between the public and the private sectors. Results of the study are consistent with the dual labour market theory and indicate that the labour market in the United Arab Emirates is segmented based on sectors (public versus private) and types of workers (nationals versus non-nationals). The study concludes with a discussion of the implication of these findings for the effectiveness of labour and economic policy. [source] The State Perspective on Teacher Shortage, Certification, and RecruitmentMODERN LANGUAGE JOURNAL, Issue 2 2009JAQUELINE BOTT VAN HOUTEN First page of article [source] Tell Us How You're Beating the Nursing ShortageNURSING FOR WOMENS HEALTH, Issue 1 2002Frances O'Brien RN No abstract is available for this article. [source] Limiting Financial Disincentives in Live Organ Donation: A Rational Solution to the Kidney ShortageAMERICAN JOURNAL OF TRANSPLANTATION, Issue 11 2006R. S. Gaston Availability of kidney transplantation is limited by an inadequate supply of organs, with no apparent remedy on the immediate horizon and increasing reliance on living donors (LDs). While some have advocated financial remuneration to stimulate donation, the National Organ Transplant Act (NOTA) of 1984 expressly forbids the offer of ,valuable consideration.' However, recent developments indicate some fluidity in the definition of valuable consideration while evolving international standards highlight deficiencies (particularly regarding long-term care and follow-up) in the current American system. Recognizing that substantial financial and physical disincentives exist for LDs, we propose a policy change that offers the potential to enhance organ availability as well as address concerns regarding long-term care. Donors assume much greater risk than is widely acknowledged, risk that can be approximated for the purpose of determining appropriate compensation. Our proposal offsets donor risk via a package of specific benefits (life insurance, health insurance and a small amount of cash) to minimize hazard and ensure donor interests are protected after as well as before nephrectomy. It will fund medical follow-up and enable data collection so that long-term risk can be accurately assessed. The proposal should be cost effective with only a small increase in the number of LDs, and the net benefit will become greater if removal of disincentives stimulates even further growth. As importantly, by directly linking compensation to risk, we believe it preserves the essence of kidney donation as a gift, consistent with NOTA and implementable in the United States without altering current legal statutes. [source] Solution to the Dilemma of the Migrant Labor Shortage and the Rural Labor Surplus in ChinaCHINA AND WORLD ECONOMY, Issue 4 2009Guifu Chen C25; J60; N55 Abstract Since 2003, China's labor market has been facing two coexisting crises: a rural labor surplus and a severe shortage of migrant labor. Using data from the 2000 China Health and Nutrition Survey questionnaire, which covers 288 villages in 36 counties, this paper attempts to find a solution to this dilemma. Specifically, a multinomial logit model, a Mincer-type model and a probit model are applied to examine the effect of educational level on the employment choices for rural laborers, and on the wages and the employment status of migrants. Based on the results of our analysis, we propose the implementation of policy aimed at increasing the educational level of rural dwellers, in conjunction with other policies to eliminate all artificial barriers, to facilitate the migration of rural laborers. [source] Is Teaching Experience Necessary for Reliable Scoring of Extended English Questions?EDUCATIONAL MEASUREMENT: ISSUES AND PRACTICE, Issue 2 2009Lucy Royal-Dawson Hundreds of thousands of raters are recruited internationally to score examinations, but little research has been conducted on the selection criteria for these raters. Many countries insist upon teaching experience as a selection criterion and this has frequently become embedded in the cultural expectations surrounding the tests. Shortages in raters for some of England's national examinations has led to non-teachers being hired to score a small minority of items and changes in technology have fostered this approach. For a National Curriculum test in English taken at age 14, this study investigated whether teaching experience was a necessary selection criterion for all aspects of the examination. Fifty-seven raters with different backgrounds were trained in the normal manner and scored the same 97 students' work. Accuracy was investigated using a cross-classified multilevel model of absolute score differences with accuracy measures at level 1 and raters crossed with candidates at level 2. By comparing the scoring accuracy of graduates with a degree in English, teacher trainees, experienced teachers and experienced raters, this study found that teaching experience was not a necessary selection criterion. A rudimentary model for allocation of raters to different question types is proposed and further research to investigate the limits of necessary qualifications for scoring is suggested. [source] Measuring the shortage of medical practitioners in rural and urban areas in developing countries: a simple framework and simulation exercises with data from IndiaINTERNATIONAL JOURNAL OF HEALTH PLANNING AND MANAGEMENT, Issue 2 2008Homi Katrak Abstract This paper suggests a simple framework to estimate the shortage of medical practitioners in rural and urban areas in developing countries. Shortages are defined with respect to four main considerations. The overall numbers and also the different categories of practitioners in the rural and urban areas, the relatively greater difficulties of access in the rural areas (which reduce the number of accessible practitioners) and the greater health hazards in those areas (which lead to greater need for medical treatment). The quantitative effect of these factors is examined by undertaking simulation exercises with data for the Ujjain district in Madhya Pradesh state, India and also data for that state. The simulations turned up the following results. The un-weighted total number of practitioners, per head of population, is relatively greater in the rural areas; this is because of the relatively large numbers of the unqualified doctors in those areas. On the other hand, a ,quality adjusted' total, with lower weights for the unqualified doctors, found little overall difference between the rural and urban areas. Third, allowance for rural,urban differences in the difficulties of access showed that the number of accessible practitioners is much lower in the rural areas. Fourth, rural,urban differences in the incidence of health hazards and estimates of the need for medical treatment also showed a marked shortage of practitioners in the rural areas. The main implication of the results is that developmental efforts in the rural areas, including improvements in transport facilities and reduction of health hazards, would help to greatly reduce the shortage of practitioners in those areas. Training programmes to improve the quality of practitioners in the rural areas are also required. Copyright © 2007 John Wiley & Sons, Ltd. [source] The status of school psychology: Implications of a major personnel shortagePSYCHOLOGY IN THE SCHOOLS, Issue 4 2004Michael J. Curtis The findings of earlier studies are reviewed and results of analyses of recent data are reported in presenting an overview of the current and possible future status of school psychology in the United States. Recognizing that legislation could have major, but as yet unclear, implications for the field, projections suggest that school psychology is likely to face a severe personnel shortage over the next 10 years. Projections also indicate that serious, although less severe, shortages are likely to continue through at least 2020. Shortages are predicted to vary markedly by geographical region of the country and type of school setting. Potential implications of the shortage are examined for the public schools. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 431,442, 2004. [source] Rural Illinois Hospital Chief Executive Officers' Perceptions of Provider Shortages and Issues in Rural Recruitment and RetentionTHE JOURNAL OF RURAL HEALTH, Issue 1 2006Michael Glasser PhD ABSTRACT:,Background: It is important to assess rural health professions workforce needs and identify variables in recruitment and retention of rural health professionals. Purpose: This study examined the perspectives of rural hospital chief executive officers (CEOs) regarding workforce needs and their views of factors in the recruitment and retention process. Methods: A survey was mailed to CEOs of 28 Illinois rural hospitals, in towns ranging from 3,396 to 33,530 in population size. The survey addressed CEO perceptions of number of physicians needed by specialty, need for other health professionals, and variables important to recruitment and retention. Findings: Twenty-two CEOs (79%) responded to the survey. Eighty-six percent indicated a physician shortage in the community, with 64% reporting the need for family physicians. CEOs also indicated the need for physicians in obstetrics-gynecology, general and orthopedic surgery, general internal medicine, cardiology, and psychiatry. In terms of needs for other health professionals, most often mentioned were registered nurses (91%), pharmacists (64%), and nurses' aides (46%). Related to recruitment and retention, most often mentioned by the CEOs was community attractiveness in general, followed by practice and physician career opportunities. Conclusions: CEOs offer 1 important perspective on health professions needs, recruitment, and retention in rural communities. While expressing a range of opinions, rural hospital CEOs clearly indicate the need for more primary care physicians, call for an increased capacity in nursing, and point to community development as a key factor in recruitment and retention. [source] National Study of the Relation of Primary Care Shortages to Emergency Department UtilizationACADEMIC EMERGENCY MEDICINE, Issue 3 2007Ilana B. Richman BA Background: Emergency department (ED) visit volumes are increasing nationwide. Objectives: To determine whether states with primary care shortages have higher rates of ED use. Methods: Populations residing in primary care shortage areas were abstracted from the Health Resources and Services Administration Geospatial Database. Annual ED visit volumes were available from the 2001 National ED Inventory. Population data and potential confounders were abstracted from federal data sets. All analyses were conducted at the state level. Results: Primary care shortage densities varied greatly across states, ranging from 3 (New Jersey) to 28 (Mississippi) medically underserved individuals per 100 people. States also varied in their annual ED visit densities, ranging from 23 visits (Hawaii) to 65 visits (Washington, DC) per 100 people. Of the 17 states in the top tertile for primary care shortage, 7 also were in the top tertile for ED visits. Primary care shortage density was positively associated with ED visit density. An increase of 10 medically underserved individuals per 100 people was associated with an annual increase of 4.2 ED visits per 100 people (p = 0.04). The association remained after controlling for six factors, with an increase of 10 medically underserved individuals per 100 people associated with an annual increase of 3.3 ED visits per 100 people (p = 0.04). Nevertheless, five states had high ED visit densities despite comparatively low primary care shortage densities (Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont), whereas five others had low ED visit densities despite high primary care shortage densities (Arizona, Idaho, Montana, New Mexico, and South Dakota). Conclusions: A positive association between primary care shortage densities and ED visit densities was found. Although most states adhere to this pattern, some states do not. Further investigation of this dissociation may yield additional explanations for rising ED visit volumes. [source] Evaluative mediation: In search of practice competenciesCONFLICT RESOLUTION QUARTERLY, Issue 2 2009Dorothy J. Della Noce Although there is no shortage of literature on why mediators should be allowed to give evaluations and why parties in dispute allegedly want and need evaluations, there is a relative lack of empirical literature on the subject of what exactly qualifies as competent evaluative mediation practice. The author reviews existing literature to formulate a description of the behaviors that would be considered competent in evaluative mediation practice, and to open a discussion of the implications of these findings for such contemporary fieldwide conversations as defining quality mediation, establishing performance-based competency standards, distinguishing among approaches to practice, and exploring the relationship between underlying values and practice approaches. [source] IRSS Psychology Theory: Telling Experiences Among Underrepresented IS DoctoratesDECISION SCIENCES JOURNAL OF INNOVATIVE EDUCATION, Issue 2 2006Fay Cobb Payton ABSTRACT With the changing demographics of the American workforce, the National Science Foundation, along with the U.S. Department of Commerce, has highlighted the shortage of minorities in information technology (IT) careers (http://www.ta.doc.gov/Reports/itsw/itsw.pdf). Using data from a 6-year period and the psychology Involvement-Regimen-Self Management-Social (IRSS) network theory as defined by Boice (1992), we discuss lessons learned from mentoring a group of Information Systems doctoral students who are members of a pipeline that can potentially increase the number of underrepresented faculty in business schools and who made conscious decisions to renounce the IT corporate domain. While our lessons speak to the need for more diversity awareness, we conclude that effective mentoring for underrepresented groups can and should include faculty of color (though limited in numbers) as well as majority faculty who are receptive to the needs and cultural differences of these student groups. Lastly, we draw on the work of Ethnic America to provide additional insight into our findings that are not offered by IRSS network theory. [source] Twilight Institutions: Public Authority and Local Politics in AfricaDEVELOPMENT AND CHANGE, Issue 4 2006Christian Lund ABSTRACT Public authority does not always fall within the exclusive realm of government institutions; in some contexts, institutional competition is intense and a range of ostensibly a-political situations become actively politicized. Africa has no shortage of institutions which attempt to exercise public authority: not only are multiple layers and branches of government institutions present and active to various degrees, but so-called traditional institutions bolstered by government recognition also vie for public authority, and new emerging institutions and organizations also enter the field. The practices of these institutions make concepts such as public authority, legitimacy, belonging, citizenship and territory highly relevant. This article proposes an analytical strategy for the understanding of public authority in such contexts. It draws on research from anthropologists, geographers, political scientists and social scientists working on Africa, in an attempt to explore a set of questions related to a variety of political practices and their institutional ramifications. [source] Drought, Domestic Budgeting and Wealth Distribution in Sahelian HouseholdsDEVELOPMENT AND CHANGE, Issue 5 2000Matthew Turner Over the past twenty-five years, Sahelian households have experienced recurrent harvest failure and greater reliance on remittances from migratory wage labour. Household subsistence has become less dependent on household grain stores and more on the liquidation of individual wealth stores. This study investigates how these broader changes have affected struggles between household members over obligations to support the household in the Zarmaganda region of western Niger. As the land-derived leverage of male patriarchs has declined and household dependence on individual wealth stores has increased, domestic budgeting has become more contested. Household heads make case-by-case moral claims on other household members during times of grain shortage. Women and subordinate males invoke Islamic law, which accords primary provisioning responsibility to the household head, to protect their individual wealth in times of grain deficit. This article investigates the nature of these budgetary struggles, showing how individuals' decisions to contribute individual wealth to support the household are best understood as highly situated, affected not only by the specific material conditions of the household but also the interplay of the moral, structural, and individualistic imperatives that derive from one's position within the household. Using reconstructed livestock wealth histories for the members of fifty-four households in western Niger, this study investigates the material consequences of these struggles. Male heads of corporate households, the historic managers of the household's land and agricultural labour, have lost wealth relative to their wives and married male subordinates since the drought of 1984. [source] European perspectives: a carer's viewACTA PSYCHIATRICA SCANDINAVICA, Issue 2001Ursula Brand Objective:,To present the work of the European Federation of Associations of Families of Mentally Ill People (EUFAMI) and discuss issues of concern to family carers. Method:,The problem areas identified and discussed by family carers are presented on the basis of questionnaire surveys organized by EUFAMI. Addresses of national organisations of family carers are included. Results:,A range of problem areas are identified; they include subsistence and welfare payments for the severely mentally ill, some shortage of general hospital units, problems of care co-ordination, issues of respect for family carers and family involvement. Conclusion:,The aim of best practice in mental health care throughout Europe has not yet been reached. Key activities of EUFAMI are aimed at empowerment of families and best practice in psychiatry in Europe. [source] Forming a national multicentre collaboration to conduct clinical trials: Increasing high-quality research in the drug and alcohol fieldDRUG AND ALCOHOL REVIEW, Issue 5 2010ROB SANSON-FISHER Abstract Issues. There is a shortage of high-quality intervention-based evidence in the drug and alcohol misuse field. That is, evidence based on replicated effects using rigorous methodology, to establish a causal knowledge base around ethical, cost-effective methods relevant to clinical practice. The knowledge base in this field is limited participant recruitment challenges; difficulty generalising results from single-centre studies; lack of research culture; issues in managing research teams; incentives for descriptive research; and limited expertise in research design and working in multidisciplinary teams. Approach. An Australian national multicentre collaboration is proposed to overcome these barriers, and reduce the burden of drug and alcohol misuse by increasing the number of high-quality clinical trials in this field. It would involve: selecting a representative sample of centres nation-wide with expertise in specific drug and alcohol issues; creating an expert multidisciplinary team to facilitate clinical trials; simultaneous recruitment and implementation of clinical trials across centres; establishing a virtual infrastructure; forming an independent data-integrity and methodology review panel; and attracting and allocating funding for clinical trials. Implications. The ability to allocate funding, the involvement of multidisciplinary experts in drug and alcohol research, and the establishment of infrastructure and procedures are likely to result in the national multicentre group's capacity to prescribe the type of research conducted under its auspices. Conclusion. The proposed initiative is likely to increase the volume of high-quality clinical trials in the Australian drug and alcohol field, a key step towards reducing the burden of drug and alcohol misuse.[Sanson-Fisher R, Brand M, Shakeshaft A, Haber P, Day C, Conigrave K, Mattick R, Lintzeris N, Teesson M. Forming a national multicentre collaboration to conduct clinical trials: Increasing high-quality research in the drug and alcohol field. Drug Alcohol Rev 2010;29;469,474] [source] Documenting the heroin shortage in New South WalesDRUG AND ALCOHOL REVIEW, Issue 4 2006CAROLYN DAY Abstract Australian heroin markets have recently undergone dramatic change, sparking debate about the nature of such markets. This study aimed to determine the onset, peak and decline of the heroin shortage in New South Wales (NSW), using the most appropriate available methods to detect market level changes. The parameters of the heroin shortage were determined by reviewing: reports of heroin users about availability and price (derived from the existing literature and the Illicit Drug Reporting System); qualitative interviews with injecting drug users, and health and law enforcement professionals working in the illicit drug field; and examining data on heroin seizures over the past decade. There was a marked reduction in heroin supply in NSW in early 2001. An increase in the price of heroin occurred in 2001, whereas it had decreased steadily since 1996. A reduction in purity also occurred, as reported by drug users and heroin seizures. The peak period of the shortage appears to have been January to April 2001. The market appears to have stabilised since that time, although it has not returned to pre-2001 levels: heroin prices have decreased in NSW for street grams, but not to former levels, and the price of ,caps' (street deals) remain elevated. Heroin purity in NSW has remained low, with perhaps a 10% increase above the lowest recorded levels. These data support the notion that the heroin market in NSW underwent significant changes, which appear to have involved a lasting shift in the nature of the market. [source] Changes in the initiation of heroin use after a reduction in heroin supplyDRUG AND ALCOHOL REVIEW, Issue 4 2006CAROLYN DAY Abstract Increasing heroin use in Australia over the past 30 years has been associated with a decline in the age of initiation to heroin use. The 2001 Australian heroin shortage was used to assess the effects of a reduction in heroin supply on age of initiation into heroin injecting. Data collected from regular injecting drug users (IDU) over the period 1996,2004 as part of the Australian Illicit Drug Reporting System were examined for changes in self-reported age of first heroin use after the onset of the heroin shortage. Estimates were also made of the number of young people who may not have commenced injecting heroin during the heroin shortage. The proportion of IDU interviewed in the IDRS who were aged ,24 years decreased from 46% in 1996 to 12% in 2004, with the most marked drop in 2001, the year in which there was an abrupt and marked reduction in heroin availability. Of those who reported first injecting between 1993 and 2000, similar proportions reported heroin and amphetamine as the first drug injected. After 2000, methamphetamine was the drug most often reported as being the first injected. Estimates suggested that between 2745 and 10 560 young people may not have begun to inject heroin in 2001 as a result of reduced heroin supply. If around one in four of these young users had progressed to regular or dependent heroin use, then there may have been a reduction of between 700 and 2500 dependent heroin users. There was an increase in amphetamine injecting but it is unclear to what extent any reduction in heroin injecting has been offset by increased amphetamine injecting. Reduced heroin availability probably resulted in a reduction in the number of new heroin injectors in Australia. Efforts need to be made to reduce the chances that young people who have initiated methamphetamine injecting do not move to heroin injecting when the heroin supply returns. [source] Channel sedimentation and erosion of the Jiangsu reach of the Yangtze River during the last 44 yearsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2009Wang Jian Abstract River channel sedimentation in the lower reaches of the Yangtze River can be affected by both changes in sea level and changes in solid discharge from the upper river. To evaluate dynamic changes of sedimentation and erosion in the Jiangsu reach of the Yangtze River (about 330 km in length) from 1959 to 2003, databases were designed and constructed using a digital elevation model (DEM) of channel topography based on the Jiangsu River Relief Map for 1959, 1970, 1985, 1992, and 2003. The results indicated that the main course of the Yangtze River in Jiangsu Province had experienced an obvious switch from sedimentation to erosion status around 1985 because of the decreasing amount of solid load from the upper parts of the river channel after that year. The sedimentation process in the main course of the Jiangsu reach of the Yangtze River demonstrated the propulsive process of ,downstream-ward aggradations.' Between 1985 and 2003, the erosion rate of the lower segment was greater than those of the middle and upper segments; this is probably because both channel flow and tide current had influenced the lower segment. When channel flow combines with tide current in the same direction, channel erosion can be intensified, especially if there is a solid load shortage in the channel. Copyright © 2009 John Wiley & Sons, Ltd. [source] Reservoir siltation in the semi-arid highlands of northern Ethiopia: sediment yield,catchment area relationship and a semi-quantitative approach for predicting sediment yieldEARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2006L. Tamene Abstract Due to shortage of rainfall and its increasing variability, moisture stress is identified to be one of the most critical factors affecting agricultural productivity in the drylands of Ethiopia. To circumvent this problem, a strategy of supplemental irrigation through surface water harvesting was adopted by the government and several micro-dams have been built in the semi-arid parts of the country. However, the benefits from the water harvesting schemes are not sustainable because of rapid water storage loss due to siltation. There is, therefore, an urgent need for improved catchment-based erosion control and sediment management strategies. The design and implementation of such strategies require data on the rate and magnitude of sediment deposition. To this end, reservoir surveys were conducted to estimate sediment deposition rate for 11 reservoirs identified to be representative of catchments in the Tigray region of northern Ethiopia. Two approaches were employed during the survey: one was based on measurement of sediment thickness in reservoirs while the other was based on comparing the original and existing topography of the reservoir-beds. The average annual sediment yield estimated for the study sites was about 19 t ha,1 y,1. An equation of the type SSY = 3á36A0á67 (with SSY = area specific sediment yield in t ha,1 y,1 and A = catchment area in km2) was also established for the study region, which is opposite to the ,universal' SSY,A relationship. In order to improve the sediment yield predictive capability of A, it was integrated with a factorial index that assesses the catchment's propensity to erosion and potential sediment yield. The effect of accelerated sediment deposition on water storage loss of reservoirs and possible controlling factors of the SSY,A relationship are outlined. The potential semi-quantitative scoring approach to characterize catchments in terms of erosion sensitivity and the significance of the A -index approach to predict SSY of similar catchments are also highlighted. Copyright © 2006 John Wiley & Sons, Ltd. [source] Flexibility in the composition and concentration of amino acids in honeydew of the drepanosiphid aphid Tuberculatus quercicolaECOLOGICAL ENTOMOLOGY, Issue 6 2002Izumi Yao Abstract 1. Mutualistic interactions between aphids and ants are mediated by honeydew that aphids produce. Previous work showed that when attended by the ant Formica yessensis Forel (Hymenoptera: Formicidae), nymphs of the aphid Tuberculatus quercicola (Matsumura) (Homoptera: Aphididae) developed into significantly smaller adults with lower fecundity than did nymphs that were not ant attended. 2. This study tested the hypothesis that this cost of ant attendance arises through changes in the quality and quantity of honeydew. Ant-attended and ant-excluded aphid colonies were prepared in the field. The composition and concentration of amino acids were compared between the honeydew produced by ant-attended colonies and that produced by ant-excluded colonies. 3. The aphids excreted smaller droplets of honeydew, but also excreted them more frequently, in ant-attended colonies than in ant-excluded colonies. The honeydew of ant-attended aphids contained more types of amino acid, and a significantly higher total concentration of amino acids, than did the honeydew of ant-excluded aphids. 4. These results suggest that the increase in the concentration of amino acids in honeydew leads to a shortage of nitrogen available for aphid growth and reproduction, resulting in lower performance under ant attendance. 5. With the advance of seasons, a significant reduction was found in both the total free amino acid concentration in phloem sap and the frequency of honeydew excretion; however the total concentration of amino acids in the honeydew did not vary significantly during the seasons, suggesting that aphids keep the quality of honeydew constant in order to maintain ant visitation. [source] Inter-sexual differences in the immune response of Eurasian kestrel nestlings under food shortageECOLOGY LETTERS, Issue 1 2002Juan A. Fargallo When resources are limited, parents should decide the optimal number, size, and sex of progeny, and offspring should decide the optimal allocation of resources to different costly functions, such as growth and immunity. We manipulated clutch sizes of Eurasian kestrels by one egg to estimate possible cumulative effects of incubation and chick rearing costs on parental body condition, feeding effort, and offspring viability. No obvious effects of clutch size manipulations on feeding effort were found while feeding effort was adjusted to the original clutch size. Enlarged and control nests suffered from higher nestling mortality than reduced nests, and chicks of the enlarged group were in poorer body condition than chicks of the reduced group. Controlling for body mass, male chicks exhibited lower cell-mediated immunity assessed by a cutaneous hypersensitivity response than females, but only in treatments suffering from food restrictions, as indicated by chick starvation. These novel results reveal inter-sexual differences in physiological strategies in early life, suggesting sex-related differences in susceptibility to disease and consequently in survival prospects of offspring. 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