482 research outputs found

    Incidence and control of bovine gastrointestinal nematodes in the East of the Province of La Pampa, Argentina

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    A cross-sectional survey including 350 stocking farms and bovine establishments that operate the full cycle (FC) as well as fattening operations (IN) was carried out in the East of the Province of La Pampa to record cases of verminous gastroenteritis (VGE) as well as control and management practices applied by the farmers.Farms were stratified by herd size into three categories: more than 900 (G), 900-500 (M) and 500-300 (P) bovines. Samples from each category were collected at random. 33% of the farmers surveyed indicated that their animals had been affected by clinical cases of VGE with morbidity and mortality rates between 11.2% and 0.42%, respectively. More cases of VEG (P<0.004, X2 8.33) occurred in herds on FC establishments (37%) that on fattening farms (IN) (21%); the relative risk (RR) was 1.77 (95%; IC 1.18 – 2.74) but no differences were noted between categories. Ninety-four percent of the farmers use avermectins alone (AVM) (71%) or combined with benzimidazole (BZD, 20%) or levamisole (3%); 6% use BZD alone. The percentage of use of other drugs in addition to AVM increases (P<0.005, X2 7.80) with larger herds (G: 32%, M: 21%, P: 15%). Of the treatments, 95.2% include avermectins alone in injectable form (82.6%) or combined with oral (16.5%) or intraruminal (0.9%) forms. Approximately 2.42 treatments per year are performed and are more prevalent (P<0.01) in G and IN farms (2.7 treatments). 35% of the farmers deworm twice a year, in the fall (between March and July) and in late winter-spring (between August and October-), 16% deworm only once (between February and April) and 12% twice (between late summer and early winter). 18% of the farmers (G: 24%, M: 18%; P: 13%) prevent VGE losses by administering treatment at a specific time of the year. 60% of the farmers consult the veterinarian although only 29% perform an egg count (hpg) although differences (P<0.001) between herd sizes were noted: G: 41%, M: 26%; P 19%. 12% (FC 10%; IN 16%). 12% of the farmers (FC 10%; IN 16%) perform a follow-up of parasite infections with an egg count and administer treatment based on this monitoring and the recommendation of a veterinarian. 94% of those surveyed indicated that VGE alone (55%) or in conjunction with other pathologies were a major problem and 30% said it was the main health problem. The study shows the economic importance of GIPs for the competitiveness of the systems in the region. The use of a significant quantity of anthelmintics, mainly avermectins, and a low participation of veterinarians in planning the controls were observed. A trend indicating that large farms and fattening operations assign more importance to control, use of anthelmintics and participation of professionals was noted

    D-brane Solitons in Supersymmetric Sigma-Models

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    Massive D=4 N=2 supersymmetric sigma models typically admit domain wall (Q-kink) solutions and string (Q-lump) solutions, both preserving 1/2 supersymmetry. We exhibit a new static 1/4 supersymmetric `kink-lump' solution in which a string ends on a wall, and show that it has an effective realization as a BIon of the D=4 super DBI-action. It is also shown to have a time-dependent Q-kink-lump generalization which reduces to the Q-lump in a limit corresponding to infinite BI magnetic field. All these 1/4 supersymmetric sigma-model solitons are shown to be realized in M-theory as calibrated, or `Q-calibrated', M5-branes in an M-monopole background.Comment: 16 pages, 3 figures, Late

    The stimulatory effect of albumin on luteinizing hormone-stimulated Leydig cell steroid production depends on its fatty acid content and correlates with conformational changes

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    __Abstract__ The effects of purified albumin species and albumin fragments (0.2–1% w/v) on short-term (4 h) steroid secretion by immature rat Leydig cells, in the presence of a maximally stimulating dose of luteinizing hormone (LH), were investigated. Human albumin and the peptic fragment (comprising residues 1–387) enhanced pregnenolone production in isolated rat Leydig cells, whereas chicken albumin and the tryptic fragment (comprising residues 198–585) were not active. This stimulatory effect of human albumin and the peptic fragment correlated with the potential of these proteins to undergo a pH-dependent neutral-to-base transition as measured by circular dichroism. The tryptic fragment and chicken albumin did not have the potential to undergo such a transition. The pH-dependent conformational changes of albumin and fragments thereof occurred in parallel with a change in the binding affinity for testosterone and pregnenolone. The fatty acid oleic acid and the drug suramin, only when present in a molar ligand-to-albumin ratio equal to or higher than 2, inhibited the albumin-mediated stimulation of steroid production. These data show that the stimulatory effects of albumin species on LH-induced Leydig cell pregnenolone production depend on their fatty acid content and correlate with the potential of these molecules to undergo conformational changes. It is unknown via which mechanisms albumin exerts its stimulatory effect, but the LH action through the cyclic AMP pathway seems not to be affected

    Emergence of Anti-Cancer Drug Resistance: Exploring the Importance of the Microenvironmental Niche via a Spatial Model

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    Practically, all chemotherapeutic agents lead to drug resistance. Clinically, it is a challenge to determine whether resistance arises prior to, or as a result of, cancer therapy. Further, a number of different intracellular and microenvironmental factors have been correlated with the emergence of drug resistance. With the goal of better understanding drug resistance and its connection with the tumor microenvironment, we have developed a hybrid discrete-continuous mathematical model. In this model, cancer cells described through a particle-spring approach respond to dynamically changing oxygen and DNA damaging drug concentrations described through partial differential equations. We thoroughly explored the behavior of our self-calibrated model under the following common conditions: a fixed layout of the vasculature, an identical initial configuration of cancer cells, the same mechanism of drug action, and one mechanism of cellular response to the drug. We considered one set of simulations in which drug resistance existed prior to the start of treatment, and another set in which drug resistance is acquired in response to treatment. This allows us to compare how both kinds of resistance influence the spatial and temporal dynamics of the developing tumor, and its clonal diversity. We show that both pre-existing and acquired resistance can give rise to three biologically distinct parameter regimes: successful tumor eradication, reduced effectiveness of drug during the course of treatment (resistance), and complete treatment failure

    Chemostratigraphy of Neoproterozoic carbonates: implications for 'blind dating'

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    The delta C-13(carb) and Sr-87/Sr-86 secular variations in Neoproteozoic seawater have been used for the purpose of 'isotope stratigraphy' but there are a number of problems that can preclude its routine use. In particular, it cannot be used with confidence for 'blind dating'. The compilation of isotopic data on carbonate rocks reveals a high level of inconsistency between various carbon isotope age curves constructed for Neoproteozoic seawater, caused by a relatively high frequency of both global and local delta C-13(carb) fluctuations combined with few reliable age determinations. Further complication is caused by the unresolved problem as to whether two or four glaciations, and associated negative delta C-13(carb) excursions, can be reliably documented. Carbon isotope stratigraphy cannot be used alone for geological correlation and 'blind dating'. Strontium isotope stratigraphy is a more reliable and precise tool for stratigraphic correlations and indirect age determinations. Combining strontium and carbon isotope stratigraphy, several discrete ages within the 590-544 Myr interval, and two age-groups at 660-610 and 740-690 Myr can be resolved

    Supersymmetric Intersecting Domain Walls in Massive Hyper-Kahler Sigma Models

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    The general scalar potential of D-dimensional massive sigma-models with eight supersymmetries is found for D=3,4D=3,4. These sigma models typically admit 1/2 supersymmetric domain wall solutions and we find, for a particular hyper-K\"ahler target, exact 1/4 supersymmetric static solutions representing a non-trivial intersection of two domain walls. We also show that the intersecting domain walls can carry Noether charge while preserving 1/4 supersymmetry. We briefly discuss an application to the D1-D5 brane system.Comment: 14 pages, Latex. Various changes including the inclusion of an exact intersecting domain wall solutio

    Gravitational Radiation from Compact Binary Pulsars

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    An outstanding question in modern Physics is whether general relativity (GR) is a complete description of gravity among bodies at macroscopic scales. Currently, the best experiments supporting this hypothesis are based on high-precision timing of radio pulsars. This chapter reviews recent advances in the field with a focus on compact binary millisecond pulsars with white-dwarf (WD) companions. These systems - if modeled properly - provide an unparalleled test ground for physically motivated alternatives to GR that deviate significantly in the strong-field regime. Recent improvements in observational techniques and advances in our understanding of WD interiors have enabled a series of precise mass measurements in such systems. These masses, combined with high-precision radio timing of the pulsars, result to stringent constraints on the radiative properties of gravity, qualitatively very different from what was available in the past.Comment: Short review chapter to appear in "Gravitational Wave Astrophysics" by Springer-Verlag, edited by Carlos F. Sopuerta; v3: a few major corrections and updated references. Comments are welcome

    The OA Trial Bank: Meta-analysis of individual patient data from knee and hip osteoarthritis trials show that patients with severe pain exhibit greater benefit from intra-articular glucocorticoids

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    Objective: To evaluate the efficacy of intra-articular (IA) glucocorticoids for knee or hip osteoarthritis (OA) in specific subgroups of patients with severe pain and inflammatory signs using individual patient data (IPD) from existing trials. Design: Randomized trials evaluating one or more IA glucocorticoid preparation in patients with knee or hip OA, published from 1995 up to June 2012 were selected from the literature. IPD obtained from original trials included patient and disease characteristics and outcomes measured. The primary outcome was pain severity at short-term follow-up (up to 4 weeks). The subgroup factors assessed included severe pain (≥70 points, 0-100 scale) and signs of inflammation (dichotomized in present or not) at baseline. Multilevel regression analyses were applied to estimate the magnitude of the effects in the subgroups with the individuals nested within each study. Results: Seven out of 43 published randomized clinical trials (n = 620) were included. Patients with severe baseline pain had a significantly larger reduction in short-term pain, but not in mid- and long-term pain, compared to those with less severe pain at baseline (Mean Difference 13.91; 95% Confidence Interval 1.50-26.31) when receiving IA glucocorticoid injection compared to placebo. No statistical significant interaction effects were found between inflammatory signs and IA glucocorticoid injections compared to placebo and to tidal irrigation at all follow-up points. Conclusions: This IPD meta-analysis demonstrates that patients with severe knee pain at baseline derive more benefit from IA glucocorticoid injection at short-term follow-up than those with less severe pain at baseline

    The Boundary-spanning Role of Democratic Learning Communities: Implementing the IDEALS

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    This multi-case study investigates characteristics and practices in schools that expand the traditional boundaries of school leadership and transform schools into democratic learning communities based on the level of implementation of the IDEALS framework. This investigation serves as a modus to illuminate democratic processes that change schools and address the needs of the students, not the needs of the adults in the system. A sample of five purposefully selected high schools, from the Midwest USA, was utilized. The schools serve Grade 9—12 students, but vary in size, residential area and socioeconomic status of the students. This study illuminates some of the challenges and strategies that facilitate or impede the process of creating more democratic schools that expand the boundaries of inquiry and discourse to include a broader range of community stakeholders and that respect and embrace issues of equity.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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