163 research outputs found

    Effects of acephate on the distribution of tarnished plant bugs within the cotton plant profile

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    The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is a primary pest of cotton in the mid-southern United States. Chemical control strategies are the primary integrated pest management tool used to manage this pest in cotton. A better understanding of tarnished plant bug behavior and distribution on cotton plants is needed to improve the scouting and monitoring protocols used to estimate population and crop injury levels needed to initiate treatments. This pest frequently re-infests fields after insecticide treatments. Sampling protocols should consider the sub-lethal effects of insecticides on migrating populations or on survivors that remain on insecticide-treated plants. Studies were performed during 2007-2008 to evaluate the effects of acephate on tarnished plant bug nymph age-classes, preference for selected fruiting structures, and vertical distribution within the cotton canopy. The test sites included flowering stage cotton plants that were infested with native populations of nymphs (\u3e1 insect / row ft). Non-treated and acephate-treated (Orthene 90SP 0.8 lb AI/acre) cotton plants were evaluated at 0 (pre-treatment) to 120 hours after treatment (HAT). Numbers of small (1st ¨C 3rd instars) nymphs were significantly greater than large (¡Ý4th instars) on non-treated plants, but no differences between age-classes were detected on acephate-treated plants. Regardless of insecticide treatment, nymphs were significantly greater on flower buds (squares) compared to bolls or white flowers. Nymphs were greater on sympodial branches of plant main stem nodes 1-5 (top five) and 6-10 compared to those on main stem nodes 11-15 for both treatments. On non-treated plants, the numbers of nymphs found on nodes 1-5 compared to those on 6-10 were not significantly different. However, on acephate-treated plants from 24 to 72 HAT, more nymphs were found on sympodial branches 6-10 compared to sympodial branches 1-5. The results of this study showed that acephate influenced tarnished plant bug nymph age-class, short-term vertical distribution on cotton plants, but did not change the preference for squares. Whole-plant sampling protocols that measure infestations throughout a cotton plant¡¯s entire profile or examination of squares for injury should provide the best estimate of tarnished plant bugs on non-treated and insecticide (acephate)-treated cotton plants

    Aerosols, Hurricanes, and their Interactions : A Case Study of Hurricane Sandy

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    While the effects of aerosols on precipitation have been studied, their effects on more extreme precipitation events like Tropical Cyclones have only been questioned relatively recently. Because of the rarity of the intersection of significant quantities of aerosols and forming/formed tropical cyclones, as well as the possible destruction caused, most experiments about their effects take place in computer models that may not fully simulate the effects of the aerosols. Limitations in satellite sensing make it difficult to track processes and material distributions in hurricanes from afar as well. Hurricane Sandy, a devastating hurricane that formed in October of 2012, may have formed while influenced by relatively smaller but still significant amounts of dust from an African dust event. Since this quantity is different from most heavy polluting scenarios that are simulated, evaluating the extent of the presence, position, and activation of aerosols within this hurricane may give us insight into the potential influences of aerosols in tropical cyclones. MODIS, MISR, AIRS, and CALIPSO data, while having limitations, is analyzed. The extent and possible effects of additional Saharan dust aerosol loading is discussed

    Risk of Secondary Malignant Neoplasms From Proton Therapy and Intensity-Modulated X-Ray Therapy for Early-Stage Prostate Cancer

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    Purpose: To assess the risk of a secondary malignant neoplasm (SMN) from proton therapy relative to intensity-modulated radiation therapy (IMRT) using X-rays, taking into account contributions from both primary and secondary sources of radiation, for prostate cancer. Methods and Materials: A proton therapy plan and a 6-MV IMRT plan were constructed for 3 patients with early-stage adenocarcinoma of the prostate. Doses from the primary fields delivered to organs at risk of developing an SMN were determined from treatment plans. Secondary doses from the proton therapy and IMRT were determined from Monte Carlo simulations and available measured data, respectively. The risk of an SMN was estimated from primary and secondary doses on an organ-by-organ basis by use of risk models from the Committee on the Biological Effects of Ionizing Radiation. Results: Proton therapy reduced the risk of an SMN by 26% to 39% compared with IMRT. The risk of an SMN for both modalities was greatest in the in-field organs. However, the risks from the in-field organs were considerably lower with the proton therapy plan than with the IMRT plan. This reduction was attributed to the substantial sparing of the rectum and bladder from exposure to the therapeutic beam by the proton therapy plan. Conclusions: When considering exposure to primary and secondary radiation, proton therapy can reduce the risk of an SMN in prostate patients compared with contemporary IMRT. © 2009 Elsevier Inc. All rights reserved

    Developmental regulation of Foxp3 expression during ontogeny

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    Thymectomy of neonatal mice can result in the development of autoimmune pathology. It has been proposed that thymic output of regulatory T (T reg) cells is delayed during ontogeny and that the development of autoimmune disease in neonatally thymectomized mice is caused by the escape of self-reactive T cells before thymectomy without accompanying T reg cells. However, the kinetics of T reg cell production within the thymus during ontogeny has not been assessed. We demonstrate that the development of Foxp3-expressing T reg cells is substantially delayed relative to nonregulatory thymocytes during ontogeny. Based on our data, we speculate that induction of Foxp3 in developing thymocytes and, thus, commitment to the T reg cell lineage is facilitated by a signal largely associated with the thymic medulla

    Reducing stray radiation dose to patients receiving passively scattered proton radiotherapy for prostate cancer

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    Proton beam radiotherapy exposes healthy tissue to stray radiation emanating from the treatment unit and secondary radiation produced within the patient. These exposures provide no known benefit and may increase a patient\u27s risk of developing a radiogenic second cancer. The aim of this study was to explore strategies to reduce stray radiation dose to a patient receiving a 76 Gy proton beam treatment for cancer of the prostate. The whole-body effective dose from stray radiation, E, was estimated using detailed Monte Carlo simulations of a passively scattered proton treatment unit and an anthropomorphic phantom. The predicted value of E was 567 mSv, of which 320 mSv was attributed to leakage from the treatment unit; the remainder arose from scattered radiation that originated within the patient. Modest modifications of the treatment unit reduced E by 212 mSv. Surprisingly, E from a modified passive-scattering device was only slightly higher (109 mSv) than from a nozzle with no leakage, e.g., that which may be approached with a spot-scanning technique. These results add to the body of evidence supporting the suitability of passively scattered proton beams for the treatment of prostate cancer, confirm that the effective dose from stray radiation was not excessive, and, importantly, show that it can be substantially reduced by modest enhancements to the treatment unit. © 2008 Institute of Physics and Engineering in Medicine

    The zero forcing numbers and propagation times of gear graphs and helm graphs

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    Zero forcing is a dynamic coloring process on graphs. Initially, each vertex of a graph is assigned a color of either blue or white, and then a process begins by which blue vertices force white vertices to become blue. The zero forcing number is the cardinality of the smallest set of initially blue vertices which can force the entire graph to become blue, and the propagation time is the minimum number of steps in such a zero forcing process. In this paper we will determine the zero forcing numbers and propagation times of two infinite classes of graphs called gear graphs and helm graphs

    AAPM Medical Physics Practice Guideline 2.a: Commissioning and quality assurance of X-ray–based image-guided radiotherapy systems

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    The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education, and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. 1

    Mechanisms Underlying HIV Associated Non-infectious Lung Disease

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    Pulmonary disease remains a primary source of morbidity and mortality in persons living with HIV (PLWH), although the advent of potent combination antiretroviral therapy has resulted in a shift from predominantly infectious to noninfectious pulmonary complications. PLWH are at high risk for COPD, pulmonary hypertension, and lung cancer even in the era of combination antiretroviral therapy. The underlying mechanisms of this are incompletely understood, but recent research in both human and animal models suggests that oxidative stress, expression of matrix metalloproteinases, and genetic instability may result in lung damage, which predisposes PLWH to these conditions. Some of the factors that drive these processes include tobacco and other substance use, direct HIV infection and expression of specific HIV proteins, inflammation, and shifts in the microbiome toward pathogenic and opportunistic organisms. Further studies are needed to understand the relative importance of these factors to the development of lung disease in PLWH

    The Compound Action Potential in Subjects Receiving a Cochlear Implant

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    The compound action potential (CAP) is a purely neural component of the cochlea’s response to sound, and may provide information about the existing neural substrate in cochlear implant (CI) subjects that can help account for variance in speech perception outcomes
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