20,295 research outputs found

    Political allocation of U.S. agriculture disaster payments in the 1990s

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    Legislation passed during the 1990s attempted to move U.S. agriculture disaster relief to a more market oriented process. The failure of this legislation has been attributed to the political system behind agricultural disaster relief. This paper explores the impact of political influence on the allocation of U.S. direct agriculture disaster payments. The results reveal that disaster payments are not based solely on need, but are higher in those states represented by public officials key to the allocation of relief. The effectiveness of legislation aimed at promoting more efficient disaster payments systems, such as crop insurance, over direct cash payments is also examined.Agriculture ; Disaster relief

    Efficacy of Different Pet Treat Formulations to Prevent Infestation by the Mite Tyrophagus putrescentiae

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    The pet food industry is a major part of the high-value processed food market in the USA and worldwide. Pest control associated with pet foods is an important activity. The mite Tyrophagus putrescentiae is a prolific cosmopolitan species that can infests high-value pet treats undetected until the infestations increase to very large numbers. Propylene glycol is a food-safe additive used to prevent mite infestations (Zhang et al., 2018; Abbar et al. 2015). Unfortunately, propylene glycol in certain foods can harm pets, and many companies are changing formulations. Here we conducted forced infestation of mites on three experimental pet treats and compared these to the current product that contains propylene glycol for susceptibility to mite infestation. We confirmed that the current product with propylene glycol did not support any mite population growth after a forced infestation with 20 mites. Two of the test formulations showed promise in preventing mite infestation, but one formulation was clearly susceptible to mites

    Clinical outcomes and patterns of care in the treatment of carcinosarcoma of the breast

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    Purpose: Carcinosarcoma of the breast is a rare yet highly aggressive tumor accounting for \u3c1% of all breast cancers, for which guidance on optimal management and prognosis are sparse. The purpose of this study was to investigate population-based treatment patterns and overall survival (OS) outcomes in patients with this diagnosis. Materials and Methods: We queried the National Cancer Database for patients diagnosed with carcinosarcoma of the breast. All patients included were treated with surgery in the form of mastectomy or lumpectomy, with or without chemotherapy and/or radiation therapy. Patients with metastatic disease were excluded. Kaplan-Meier analysis was used to estimate OS. Univariate and multivariable Cox analyses were used to determine predictive factors of OS. Results: A total of 329 patients from 2004 to 2012 were identified. Median age at diagnosis was 58 years (range, 24-90). Patients had T1 (21%), T2 (44%), T3 (25%), or T4 disease (10%). Most patients were node-negative at diagnosis (77%). Breast conservation surgery was utilized in 33% of patients. Chemotherapy was used in 66% of patients. Less than half (44%) of patients received radiation therapy to a median dose of 50.4 Gy (range 35-56 Gy), with a median 10 Gy boost used in 76%. With a median follow-up of 40.0 months, 3- and 5-year OS for all patients was 74% and 60%, respectively. Kaplan-Meier estimates revealed the 3-yr OS was 80% in patients receiving chemotherapy vs 59% without chemotherapy (P \u3c 0.001). The 3-yr OS was 82% in patients receiving RT vs 66% without RT (P = 0.001). On multivariable analysis, OS was significantly influenced by Charlson-Deyo comorbidity index, insurance status, clinical T stage, surgical margin status, and treatment group, with trimodality therapy (HR: 0.45, 95% CI: 0.27-0.78; P = 0.004) and surgery plus CT (HR: 0.54, 95% CI: 0.33-0.90; P = 0.02) being associated with the greatest OS. Logistic regression revealed only younger patients were more likely to receive trimodality therapy. Conclusions: Carcinosarcoma of the breast is associated with relatively poor rates of OS. The addition of CT and RT to surgery improves OS. Trimodality therapy and surgery plus CT were associated with the greatest OS compared to surgery alone

    Guided Graph Spectral Embedding: Application to the C. elegans Connectome

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    Graph spectral analysis can yield meaningful embeddings of graphs by providing insight into distributed features not directly accessible in nodal domain. Recent efforts in graph signal processing have proposed new decompositions-e.g., based on wavelets and Slepians-that can be applied to filter signals defined on the graph. In this work, we take inspiration from these constructions to define a new guided spectral embedding that combines maximizing energy concentration with minimizing modified embedded distance for a given importance weighting of the nodes. We show these optimization goals are intrinsically opposite, leading to a well-defined and stable spectral decomposition. The importance weighting allows to put the focus on particular nodes and tune the trade-off between global and local effects. Following the derivation of our new optimization criterion and its linear approximation, we exemplify the methodology on the C. elegans structural connectome. The results of our analyses confirm known observations on the nematode's neural network in terms of functionality and importance of cells. Compared to Laplacian embedding, the guided approach, focused on a certain class of cells (sensory, inter- and motoneurons), provides more biological insights, such as the distinction between somatic positions of cells, and their involvement in low or high order processing functions.Comment: 43 pages, 7 figures, submitted to Network Neuroscienc

    Tail approximation for the chemical master equation

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    The chemical master equation is a differential equation describing the time evolution of the probability distribution over the possible “states” of a biochemical system. The solution of this equation is of interest within the systems biology field ever since the importance of the molec- ular noise has been acknowledged. Unfortunately, most of the systems do not have analytical solutions, and numerical solutions suffer from the course of dimensionality and therefore need to be approximated. Here, we introduce the concept of tail approximation, which retrieves an approximation of the probabilities in the tail of a distribution from the total probability of the tail and its conditional expectation. This approximation method can then be used to numerically compute the solution of the chemical master equation on a subset of the state space, thus fighting the explosion of the state space, for which this problem is renowned

    Variability in supply and cross-shelf transport of pink shrimp (Farfantepenaeus duorarum) postlarvae into western Florida Bay

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    The variability in the supply of pink shrimp (Farfantepenaeus duorarum) postlarvae and the transport mechanisms of planktonic stages were investigated with field data and simulations of transport. Postlarvae entering the nursery grounds of Florida Bay were collected for three consecutive years at channels that connect the Bay with the Gulf of Mexico, and in channels of the Middle Florida Keys that connect the southeastern margin of the Bay with the Atlantic Ocean. The influx of postlarvae in the Middle Florida Keys was low in magnitude and varied seasonally and among years. In contrast, the greater postlarval influx occurred at the northwestern border of the Bay, where there was a strong seasonal pattern with peaks in influx from July through September each year. Planktonic stages need to travel up to 150 km eastward between spawning grounds (northeast of Dry Tortugas) and nursery grounds (western Florida Bay) in about 30 days, the estimated time of planktonic development for this species. A Lagrangian trajectory model was developed to estimate the drift of planktonic stages across the SW Florida shelf. The model simulated the maximal distance traveled by planktonic stages under various assumptions of behavior. Simulation results indicated that larvae traveling with the instantaneous current and exhibiting a diel behavior travel up to 65 km and 75% of the larvae travel only 30 km. However, the eastward distance traveled increased substantially when a larval response to tides was added to the behavioral variable (distance increased to 200 km and 85% of larvae traveled 150 km). The question is, when during larval development, and where on the shallow SW Florida shelf, does the tidal response become incorporated into the behavior of pink shrimp

    Variability of Red Supergiants in M31 from the Palomar Transient Factory

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    Most massive stars end their lives as Red Supergiants (RSGs), a short-lived evolution phase when they are known to pulsate with varying amplitudes. The RSG period-luminosity (PL) relation has been measured in the Milky Way, the Magellanic Clouds and M33 for about 120 stars in total. Using over 1500 epochs of R-band monitoring from the Palomar Transient Factory (PTF) survey over a five-year period, we study the variability of 255 spectroscopically cataloged RSGs in M31. We find that all RGSs brighter than M_K~ -10 mag (log(L/L_sun)>4.8) are variable at dm_R>0.05 mag. Our period analysis finds 63 with significant pulsation periods. Using the periods found and the known values of M_K for these stars, we derive the RSG PL relation in M31 and show that it is consistent with those derived earlier in other galaxies of different metallicities. We also detect, for the first time, a sequence of likely first-overtone pulsations. Comparison to stellar evolution models from MESA confirms the first overtone hypothesis and indicates that the variable stars in this sample have 12 M_sun<M<24 M_sun. As these RSGs are the immediate progenitors to Type II-P core-collapse supernovae (SNe), we also explore the implication of their variability in the initial-mass estimates for SN progenitors based on archival images of the progenitors. We find that this effect is small compared to the present measurement errors.Comment: 17 pages, 10 figure

    Negative refractive index due to chirality

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    We demonstrate experimentally and numerically that metamaterials based on bilayer cross wires give giant optical activity, circular dichroism, and negative refractive index. The presented chiral design offers a much simpler geometry and more efficient way to realize negative refractive index at any frequency. We also developed a retrieval procedure for chiral materials which works successfully for circularly polarized waves
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