731 research outputs found

    Influence of Rice Production on the Quality of Water in Tailwater Collection Reservoirs

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    Since maintaining high water quality standards in the state remains a high priority, monitoring for pesticides in water sources must continue. Determining the type, concentration, and characteristics of any pesticides present in water supplies are essential to the overall assessment of water quality. Five independent locations, implementing contained water management systems and recyclable water, were monitored in 1995 and 1996. Irrigation, runoff, and pond water samples were collected every 10 to 14 days between permanent flood establishment and draining. Water samples were transported to the laboratory and extracted for 16 pesticides using solid phase extraction (SPE) techniques. Quantification and confirmation of pesticide residues were obta1ned by HPLC and GC/MS analysis. The lower limit of quantitation for all pesticides was between 1.0 -1.3 pg L-1 in water. Pesticides selected for monitoring were determined after assessing state recommendations and our analytical capabilities. Pesticides included: benomyl, bensulfuron methyl, carbaryl, carbofuran, 2,4-D, fenoxaprop ethyl, propiconazole, malathion, MCPA, methyl parathion, molinate, pendimethalin, propanil, iprodione, quinclorac, triclopyr, and thiobencarb. Since each field location was independently managed, individual results are site specific. 2,4-D, benomyl, molinate, propanil, quinclorac, thiobencarb, and pendimethalin were the pesticides actually applied during the seasons. These pesticides were detected, usually at trace levels, in tailwaters shortly after application but did not appear to buildup in the reservoirs. Quinclorac residues in the tailwaters were more persistent (up to 8 weeks) than the other detected compounds (less than 2 weeks)

    Child nutrition, child health, and school enrollment : a longitudinal analysis

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    Better health and nutrition are thought to improve children's performance in school, and therefore their productivity after school. Most literature ignores the fact that child health and schooling reflect behavioral choices, so the estimated impact of health and nutrition on a child's schooling reflects biases in the studies. Using an explicit dynamic model for preferred estimates, the authors use longitudinal data to investigate how children's health and nutrition affect school enrollment in rural Pakistan. They use price shocks when children were of preschool age to control for behavior determining the measure of children's health and nutrition stock. The authors find that children's health and nutrition is three times more important for enrollment than is suggested by"naive estimates"that assume that children's health and nutrition is predetermined rather that determined by household choices. Not only does improved nutrition increase enrollments, it does so more for girls, thus closing a portion of the gender gap. These results strongly reinforce the importance of using estimation methods that are consistent with the economic theory of households to explore the impact of some choice variables on others, using socioeconomic behavioral data. Private behaviors and public policies that affect the health and nutrition of children have much greater effect on school enrollment and on eventual productivity than suggested by early literature methods.Teaching and Learning,Health Monitoring&Evaluation,Primary Education,Early Child and Children's Health,Public Health Promotion,Science Education,Scientific Research&Science Parks,Economic Theory&Research,Primary Education,Health Monitoring&Evaluation

    Competition and educational quality: evidence from the Netherlands

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    Little evidence is available for the effect of competition on educational quality as only a few countries allow large-scale competition. In the Netherlands, free parental choice has been present since the beginning of the twentieth century and can be characterized as a full voucher program with 100 % funding. Based on micro panel data for the Netherlands, we show that there is a relation between competition and educational outcomes in secondary education, but that it is often negative and small, sometimes insignificant but never positive. This effect is larger for small and medium-sized schools and for schools that do not have a Protestant or Catholic denomination

    Effect of Tumor-Treating Fields Plus Maintenance Temozolomide vs Maintenance Temozolomide Alone on Survival in Patients With Glioblastoma: A Randomized Clinical Trial.

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    Tumor-treating fields (TTFields) is an antimitotic treatment modality that interferes with glioblastoma cell division and organelle assembly by delivering low-intensity alternating electric fields to the tumor. To investigate whether TTFields improves progression-free and overall survival of patients with glioblastoma, a fatal disease that commonly recurs at the initial tumor site or in the central nervous system. In this randomized, open-label trial, 695 patients with glioblastoma whose tumor was resected or biopsied and had completed concomitant radiochemotherapy (median time from diagnosis to randomization, 3.8 months) were enrolled at 83 centers (July 2009-2014) and followed up through December 2016. A preliminary report from this trial was published in 2015; this report describes the final analysis. Patients were randomized 2:1 to TTFields plus maintenance temozolomide chemotherapy (n = 466) or temozolomide alone (n = 229). The TTFields, consisting of low-intensity, 200 kHz frequency, alternating electric fields, was delivered (≥ 18 hours/d) via 4 transducer arrays on the shaved scalp and connected to a portable device. Temozolomide was administered to both groups (150-200 mg/m2) for 5 days per 28-day cycle (6-12 cycles). Progression-free survival (tested at α = .046). The secondary end point was overall survival (tested hierarchically at α = .048). Analyses were performed for the intent-to-treat population. Adverse events were compared by group. Of the 695 randomized patients (median age, 56 years; IQR, 48-63; 473 men [68%]), 637 (92%) completed the trial. Median progression-free survival from randomization was 6.7 months in the TTFields-temozolomide group and 4.0 months in the temozolomide-alone group (HR, 0.63; 95% CI, 0.52-0.76; P < .001). Median overall survival was 20.9 months in the TTFields-temozolomide group vs 16.0 months in the temozolomide-alone group (HR, 0.63; 95% CI, 0.53-0.76; P < .001). Systemic adverse event frequency was 48% in the TTFields-temozolomide group and 44% in the temozolomide-alone group. Mild to moderate skin toxicity underneath the transducer arrays occurred in 52% of patients who received TTFields-temozolomide vs no patients who received temozolomide alone. In the final analysis of this randomized clinical trial of patients with glioblastoma who had received standard radiochemotherapy, the addition of TTFields to maintenance temozolomide chemotherapy vs maintenance temozolomide alone, resulted in statistically significant improvement in progression-free survival and overall survival. These results are consistent with the previous interim analysis. clinicaltrials.gov Identifier: NCT00916409

    Air quality and error quantity: pollution and performance in a high-skilled, quality-focused occupation

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    We provide the first evidence that short-term exposure to air pollution affects the work performance of a group of highly-skilled, quality-focused employees. We repeatedly observe the decision-making of individual professional baseball umpires, quasi-randomly assigned to varying air quality across time and space. Unique characteristics of this setting combined with high-frequency data disentangle effects of multiple pollutants and identify previously under-explored acute effects. We find a 1 ppm increase in 3-hour CO causes an 11.5% increase in the propensity of umpires to make incorrect calls and a 10 mg/m3 increase in 12-hour PM2.5 causes a 2.6% increase. We control carefully for a variety of potential confounders and results are supported by robustness and falsification checks

    Treating older children with clubfoot: results of a cross-sectional survey of expert practitioners

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    Treating clubfoot in walking-age children is debated, despite studies showing that using the Ponseti casting principles can correct the midfoot effectively. We aimed to explore techniques and approaches for the management of older children with clubfoot and identify consensus areas. A mixed-methods cross-sectional electronic survey on delayed-presenting clubfoot (DPC) was sent to 88 clubfoot practitioners (response rate 56.8%). We collected data on decision-making, casting, imaging, orthotics, surgery, recurrence, rehabilitation, multidisciplinary care, and contextual factors. The quantitative data were analysed using descriptive statistics. The qualitative data were analysed using conventional content analysis. Many respondents reported using the Pirani score and some used the PAVER score to aid deformity severity assessment and correctability. Respondents consistently applied the Ponseti casting principles with a stepwise approach. Respondents reported economic, social, and other contextual factors that influenced the timing of the treatment, the decision to treat a bilateral deformity simultaneously, and casting intervals. Differences were seen around orthotic usage and surgical approaches, such as the use of tibialis anterior tendon transfer following full correction. In summary, the survey identified consensus areas in the overall principles of management for older children with clubfoot and the implementation of the Ponseti principles. The results indicate these principles are well recognised as a multidisciplinary approach for older children with clubfoot and can be adapted well for different geographical and healthcare contexts

    AUX1-mediated root hair auxin influx governs SCFTIR1/AFB-type Ca2+ signaling

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    Auxin is a key regulator of plant growth and development, but the causal relationship between hormone transport and root responses remains unresolved. Here we describe auxin uptake, together with early steps in signaling, in Arabidopsis root hairs. Using intracellular microelectrodes we show membrane depolarization, in response to IAA in a concentration- and pH-dependent manner. This depolarization is strongly impaired in aux1 mutants, indicating that AUX1 is the major transporter for auxin uptake in root hairs. Local intracellular auxin application triggers Ca2+ signals that propagate as long-distance waves between root cells and modulate their auxin responses. AUX1-mediated IAA transport, as well as IAA- triggered calcium signals, are blocked by treatment with the SCFTIR1/AFB - inhibitor auxinole. Further, they are strongly reduced in the tir1afb2afb3 and the cngc14 mutant. Our study reveals that the AUX1 transporter, the SCFTIR1/AFB receptor and the CNGC14 Ca2+ channel, mediate fast auxin signaling in roots
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