71 research outputs found

    OPPORTUNITY COSTS OF WATER LEASING: IRRIGATION, INSTREAM FLOW, AND WETLAND CONSIDERATIONS IN THE LARAMIE BASIN, WYOMING

    Get PDF
    Flood irrigation in the Laramie Basin of southeast Wyoming has created many wetlands that rely directly on irrigation inputs for water. The Laramie Basin is a proposed water source for enhancing Platte River instream flows, to the benefit of endangered cranes, terns, plovers, and sturgeons. Increasing irrigation efficiency, or retiring irrigated lands would transform Laramie Basin agriculture and cause a high fraction of the Basins wetlands to be lost. This study explores the limitations of traditional water transfer tools when regional instream-flow requirements compete for water with local irrigation-dependent wetlands. A rotating short-term water lease program is proposed. The program would allow Laramie Basin producers to contribute to instream flow without causing permanent wetland damage or loss. Short-term water leasing programs could allow agricultural communities to contribute to regional environmental water needs without sacrificing local, agriculturally-based ecological resources. An estimate of minimum water costs, advantages and disadvantages of short-term water leasing are discussed.Resource /Energy Economics and Policy,

    Assessment of cataract surgical outcomes in settings where follow-up is poor: PRECOG, a multicentre observational study

    Get PDF
    Background Poor follow-up after cataract surgery in developing countries makes assessment of operative quality uncertain. We aimed to assess two strategies to measure visual outcome: recording the visual acuity of all patients 3 or fewer days postoperatively (early postoperative assessment), and recording that of only those patients who returned for the fi nal follow-up examination after 40 or more days without additional prompting. Methods Each of 40 centres in ten countries in Asia, Africa, and Latin America recruited 40–120 consecutive surgical cataract patients. Operative-eye best-corrected visual acuity and uncorrected visual acuity were recorded before surgery, 3 or fewer days postoperatively, and 40 or more days postoperatively. Clinics logged whether each patient had returned for the fi nal follow-up examination without additional prompting, had to be actively encouraged to return, or had to be examined at home. Visual outcome for each centre was defi ned as the proportion of patients with uncorrected visual acuity of 6/18 or better minus the proportion with uncorrected visual acuity of 6/60 or worse, and was calculated for each participating hospital with results from the early assessment of all patients and the late assessment of only those returning unprompted, with results from the fi nal follow-up assessment for all patients used as the standard. Findings Of 3708 participants, 3441 (93%) had fi nal follow-up vision data recorded 40 or more days after surgery, 1831 of whom (51% of the 3581 total participants for whom mode of follow-up was recorded) had returned to the clinic without additional prompting. Visual outcome by hospital from early postoperative and fi nal follow-up assessment for all patients were highly correlated (Spearman’s rs=0·74, p<0·0001). Visual outcome from fi nal followup assessment for all patients and for only those who returned without additional prompting were also highly correlated (rs=0·86, p<0·0001), even for the 17 hospitals with unprompted return rates of less than 50% (rs=0·71, p=0·002). When we divided hospitals into top 25%, middle 50%, and bottom 25% by visual outcome, classifi cation based on fi nal follow-up assessment for all patients was the same as that based on early postoperative assessment for 27 (68%) of 40 centres, and the same as that based on data from patients who returned without additional prompting in 31 (84%) of 37 centres. Use of glasses to optimise vision at the time of the early and late examinations did not further improve the correlations. Interpretation Early vision assessment for all patients and follow-up assessment only for patients who return to the clinic without prompting are valid measures of operative quality in settings where follow-up is poor

    A system of ODEs for a Perturbation of a Minimal Mass Soliton

    Full text link
    We study soliton solutions to a nonlinear Schrodinger equation with a saturated nonlinearity. Such nonlinearities are known to possess minimal mass soliton solutions. We consider a small perturbation of a minimal mass soliton, and identify a system of ODEs similar to those from Comech and Pelinovsky (2003), which model the behavior of the perturbation for short times. We then provide numerical evidence that under this system of ODEs there are two possible dynamical outcomes, which is in accord with the conclusions of Pelinovsky, Afanasjev, and Kivshar (1996). For initial data which supports a soliton structure, a generic initial perturbation oscillates around the stable family of solitons. For initial data which is expected to disperse, the finite dimensional dynamics follow the unstable portion of the soliton curve.Comment: Minor edit

    A Study to investigate the role of p27 and Cyclin E immunoexpression as a prognostic factor in early breast carcinoma

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Cyclin E and p27 expression is easy to assess in human tissues by standard immunohistochemical techniques. Immunohistochemistry is cost effective, relatively easy to perform and will play more of a role in the future management of cancer. The aim of this study was to investigate the role of p27 and cyclin E immunoexpression as a prognostic factor in early breast carcinoma.</p> <p>Methods</p> <p>Cyclin E and p27 immunohistochemistry was performed on sixty six cases of breast carcinoma submitted over a five year period to the Division of Anatomical Pathology, Groote Schuur hospital; Whittaker and Associates; and PathCare. All tumours included in this study were less than 5 cm in diameter (pT1 and pT2 stage) and all the patients had wide local excisions performed. Follow up information was obtained from patient folders in the Department of Radiation Oncology.</p> <p>Results</p> <p>There was no significant association of cyclin E and p27 expression with distant metastasis free survival (MFS) for all invasive carcinomas in contrast to grade, lymph node spread and vascular invasion. However, there was a statistically significant direct association of cyclin E with distant metastases in all invasive carcinomas, in the subgroup of infiltrating duct carcinomas (IDC) and in the node negative group when cyclin E was stratified as negative and positive (low/high). In this study of early breast carcinoma, only 9/66 cases showed cyclin E expression. Of these, four patients had distant metastases, one patient had a local recurrence and four patients were alive at last follow-up. Furthermore, cyclin E expression was significantly associated with grade, lymph node spread, oestrogen receptor status and histological type. None of the lobular carcinomas showed cyclin E positivity and only one case of lobular carcinoma presented with distant metastases.</p> <p>59/66 cases were positive (low/high) for p27 while seven cases were negative, 22 cases showed low expression and 37 cases demonstrated high p27 expression.</p> <p>p27 was significantly associated with oestrogen receptor status only for all invasive carcinomas and in the IDC group. There was no statistical relationship between p27 and cyclin E, but 50 (76%) tumours with positive p27 expression were negative for cyclin E. There were similar results for the invasive ductal carcinoma subgroup.</p> <p>Conclusion</p> <p>This study shows that p27 and cyclin E are not good independent prognostic markers for early breast carcinoma in contrast to grade, lymph node spread and vascular invasion for all invasive carcinomas. However, cyclin E provides some prognostic value as there is a direct statistical association with the development of distant metastases. Many previous studies have correlated overexpression of cyclin E with an aggressive course. The inverse relationship between p27 and cyclin E expression which has been reported in the literature has been highlighted, but this was not statistically significant. Most cases showed positive p27 expression and negative Cyclin E expression. This may be due to the early stage of the disease.</p

    Cognitive ability, parental socioeconomic position and internalising and externalising problems in adolescence: Findings from two European cohort studies

    Get PDF
    We investigated whether cognitive ability (CA) may be a moderator of the relationship of parental socioeconomic position (SEP) with internalising and externalising problems in adolescents. We used data from two longitudinal cohort studies; the Avon Longitudinal Study of Parents and Children (ALSPAC) and the Tracking Adolescents’ Individual Lives Survey (TRAILS). Indicators of SEP were mother’s education and household income. CA was estimated with IQ scores, derived from the Wechsler Intelligence Scale for Children. Internalising and externalising problems were measured with the Strengths and Difficulties Questionnaire in ALSPAC and with the Child Behavior Checklist in TRAILS. Logistic regression analyses were used to estimate the relative index of inequality (RII) for each outcome; the RII provides the odds ratio comparing the most to least deprived for each measure of SEP. In fully adjusted models an association of mother’s education with externalising problems was observed [ALSPAC RII 1.42 (95%CI: 1.01–1.99); TRAILS RII 2.21 (95%CI: 1.37–3.54)], and of household income with internalising and externalising problems [pooled ALSPAC & TRAILS internalising RII 1.30 (95%CI: 0.99–1.71); pooled ALSPAC & TRAILS externalising RII 1.38 (95%CI: 1.03–1.84)]. No consistent associations were observed between mother’s education and internalising problems. Results of stratified analyses and interaction-terms showed no evidence that CA moderated the association of SEP with internalising or externalising problems

    Atmospheric sources of trace element contamination in cultivated urban areas: A review

    Get PDF
    Producing food in cities has garnered increasing attention over the past decade. Although there are ecological and social benefits, cultivated urban areas (CUAs) also bear contamination hazards, including from trace elements (TEs). Trace element contamination has been studied extensively in CUAs, but atmospheric sources remain understudied and poorly understood. A brief discussion is offered on atmospheric particulate deposition processes in cities and their implications for urban food production. Available findings are discussed and contrasted. Existing research assesses atmospheric deposition indirectly or otherwise lacks controls for other TE contaminants. There is little to no engagement with methodological guidelines from the atmospheric sciences, which reduces confidence in the findings so far attained. Suggestions are delineated to combine techniques used in the atmospheric sciences with the robust methodologies already generated by studies on TE contamination in CUAs, such as isotope and TE ratios analyses
    corecore