114 research outputs found

    Some theorems concerning the projection-iteration method

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    Functional diversity of chemokines and chemokine receptors in response to viral infection of the central nervous system.

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    Encounters with neurotropic viruses result in varied outcomes ranging from encephalitis, paralytic poliomyelitis or other serious consequences to relatively benign infection. One of the principal factors that control the outcome of infection is the localized tissue response and subsequent immune response directed against the invading toxic agent. It is the role of the immune system to contain and control the spread of virus infection in the central nervous system (CNS), and paradoxically, this response may also be pathologic. Chemokines are potent proinflammatory molecules whose expression within virally infected tissues is often associated with protection and/or pathology which correlates with migration and accumulation of immune cells. Indeed, studies with a neurotropic murine coronavirus, mouse hepatitis virus (MHV), have provided important insight into the functional roles of chemokines and chemokine receptors in participating in various aspects of host defense as well as disease development within the CNS. This chapter will highlight recent discoveries that have provided insight into the diverse biologic roles of chemokines and their receptors in coordinating immune responses following viral infection of the CNS

    Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results

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    The chromosphere is a thin layer of the solar atmosphere that bridges the relatively cool photosphere and the intensely heated transition region and corona. Compressible and incompressible waves propagating through the chromosphere can supply significant amounts of energy to the interface region and corona. In recent years an abundance of high-resolution observations from state-of-the-art facilities have provided new and exciting ways of disentangling the characteristics of oscillatory phenomena propagating through the dynamic chromosphere. Coupled with rapid advancements in magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly investigate the role waves play in supplying energy to sustain chromospheric and coronal heating. Here, we review the recent progress made in characterising, categorising and interpreting oscillations manifesting in the solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review

    The Cholecystectomy As A Day Case (CAAD) Score: A Validated Score of Preoperative Predictors of Successful Day-Case Cholecystectomy Using the CholeS Data Set

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    Background Day-case surgery is associated with significant patient and cost benefits. However, only 43% of cholecystectomy patients are discharged home the same day. One hypothesis is day-case cholecystectomy rates, defined as patients discharged the same day as their operation, may be improved by better assessment of patients using standard preoperative variables. Methods Data were extracted from a prospectively collected data set of cholecystectomy patients from 166 UK and Irish hospitals (CholeS). Cholecystectomies performed as elective procedures were divided into main (75%) and validation (25%) data sets. Preoperative predictors were identified, and a risk score of failed day case was devised using multivariate logistic regression. Receiver operating curve analysis was used to validate the score in the validation data set. Results Of the 7426 elective cholecystectomies performed, 49% of these were discharged home the same day. Same-day discharge following cholecystectomy was less likely with older patients (OR 0.18, 95% CI 0.15–0.23), higher ASA scores (OR 0.19, 95% CI 0.15–0.23), complicated cholelithiasis (OR 0.38, 95% CI 0.31 to 0.48), male gender (OR 0.66, 95% CI 0.58–0.74), previous acute gallstone-related admissions (OR 0.54, 95% CI 0.48–0.60) and preoperative endoscopic intervention (OR 0.40, 95% CI 0.34–0.47). The CAAD score was developed using these variables. When applied to the validation subgroup, a CAAD score of ≤5 was associated with 80.8% successful day-case cholecystectomy compared with 19.2% associated with a CAAD score >5 (p < 0.001). Conclusions The CAAD score which utilises data readily available from clinic letters and electronic sources can predict same-day discharges following cholecystectomy

    Detection of \u3ci\u3eClostridium botulinum\u3c/i\u3e Type C Cells in the Gastrointestinal Tracts of Mozambique Tilapia (\u3ci\u3eOreochromis mossambicus\u3c/i\u3e) by Polymerase Chain Reaction

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    We established a method of directly detecting Clostridium botulinum type C cells, while minimizing spore detection, in the intestinal contents of Mozambique tilapia (Oreochromis mossambicus). This technique involved extraction of predominantly cellular DNA from tilapia intestinal tracts and used a polymerase chain reaction assay to detect presence of type C1 toxin gene. We consistently detected C. botulinum type C cells in tilapia gastrointestinal contents at a level of 7.53104 cells per 0.25 g material or 1.93103 cells. This technique is useful for determining prevalence of the potentially active organisms within a given population of fish and may be adapted to other types of C. botulinum and vertebrate populations as well

    A new Puercan (early Paleocene) hyopsodontid “condylarth” from New Mexico

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    Isolated cheek teeth from the late Puercan (early Paleocene) Split Lip Flats local fauna, from the head of Willow Wash, Nacimiento Formation, San Juan Basin, represent a new genus and species of hyopsodontid “condylarth”, Chacomylus sladei. The teeth are small, bunodont, and are remarkable for the enlargement of the protocone, pronounced exodaenodonty, and high degree of attritional wear caused by transverse shearing or grinding. Although C. sladei bears a superficial resemblance to the apheliscine apheliscid Gingerichia, a preliminary phylogenetic analysis confirms that it is a hyopsodontid, closely related to the Puercan hyopsodontids Valenia wilsoni and Litomylus orthronepius

    Morphological Study of the Effects of the GnRH Superagonist Deslorelin on the Canine Testis and Prostate Gland

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    Contents The present study is part of a programme of research designed to evaluate the efficacy of the GnRH superagonist, deslorelin (d-Trp 6-Pro 9-des-Gly 10-LHRH ethylamide), as a contraceptive for male dogs. Adult dogs were assigned to a completely randomized design comprising six groups of four animals. Each dog in the control group received a blank implant (placebo) and each dog in the other five groups received a 6 mg deslorelin implant. One group of deslorelin-treated dogs was sacrificed on each of days 16, 26, 41, 101 and 620, and testicular and prostate tissues were collected for study by light and electron microscopy. On days 16 and 26 after implantation, we observed partial disruption of the seminiferous tubules, with early spermatids shed into the lumen. On days 41 and 101 after implantation, 90-100% of the seminiferous tubules were atrophic and aspermatogenic. On day 101 after implantation, 99% of all sections showed atrophy of the epithelium and shrinkage of epithelial height in the ductus epididymides. On days 41 and 101 after implantation, prostate tissue showed complete atrophy of the glandular epithelium (100% of sections) and an apparent increase in the relative proportion of connective tissue. At the electron microscopic level, in dogs treated with deslorelin for 41 and 101 days, the Sertoli cells were smaller and their nucleoli appeared smaller than in the control dogs. The nucleoli of the Leydig cells were atrophied and prostate glandular epithelium showed reduced epithelial height, atrophy of the nucleolus and an absence of secretory granules. Tissues collected during the recovery phase revealed a complete recovery of spermatogenesis. In conclusion, slow-release implants containing deslorelin induce a striking atrophy of the testes and prostate gland by 26 days after implantation, explaining the previously reported loss of ejaculate and arrest of sperm output. At histological level, the entire process appears to be completely reversible, in accordance with data on endocrine variables and semen production

    Dose-response studies for pituitary and testicular function in male dogs treated with the GnRH superagonist, deslorelin

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    We tested the effect of dose of GnRH superagonist on pituitary and testicular function in a study with four groups of four male dogs. The Controls received blank implants and the other three groups received implants containing 3, 6 or 12 mg deslorelin (d-Trp 6-Pro 9-des-Gly 10-GnRH ethylamide). In all deslorelin-treated groups, there was initially an acute increase in plasma concentrations of LH and testosterone, followed by declines such that both hormones became undetectable after approximately 12 days. There was a dose-response in some of these early aspects of the hormone profiles. With respect to long-term effects of treatment, the 12-mg dose had significantly greater effects than the smaller doses for the duration of minimum testicular volume [366 ± 77, mean ± SEM (3 mg), 472 ± 74 (6 mg), and 634 ± 59 (12 mg) days], absence of ejaculate [416 ± 88 (3 mg), 476 ± 83 (6 mg), and 644 ± 67 (12 mg) days], undetectable plasma concentrations of LH and testosterone [367 ± 64 (3 mg), 419 ± 72 (6 mg), and 607 ± 69 (12 mg) days], the delay until complete recovery of LH and testosterone secretion [394 ± 65 (3 mg), 484 ± 72 (6 mg) and 668 ± 47 (12 mg) days], and the delay until testes had regrown to normal volume [408 ± 77 (3 mg), 514 ± 74 (6 mg), 676 ± 59 (12 mg) days]. The time taken to restore full ejaculates was also longest for the 12-mg dose: 716 ± 67 (12 mg) days vs 440 ± 66 (3 mg) and 538 ± 83 (6 mg) days after implantation. There was no correlation between delay to recovery of normal ejaculate quality and body mass. We conclude that the dose-response relationship with deslorelin implants is not expressed with respect to the degree of suppression of reproduction, but on the maximum duration of suppression and thus to delay until recovery

    Business strategy, human capital, and managerial incentives.

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    We posit that the value of a manager's human capital depends on the firm's business strategy. The resulting interaction between business strategy and managerial incentives affects the organization of business activities. We illustrate the impact of this interaction on firm boundaries in a dynamic agency model. There may be disadvantages in merging two firms even when such a merger allows the internalization of externalities between the two firms. Merging, by making unprofitable certain decisions, increases the cost of inducing managerial effort. This incentive cost is a natural consequence of the manager's business-strategy-specific human capital

    Pituitary and testicular endocrine responses to exogenous gonadotrophin-releasing hormone (GnRH) and luteinising hormone in male dogs treated with GnRH agonist implants

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    The present study tested whether exogenous gonadotrophin-releasing hormone (GnRH) and luteinising hormone (LH) can stimulate LH and testosterone secretion in dogs chronically treated with a GnRH superagonist. Twenty male adult dogs were assigned to a completely randomised design comprising five groups of four animals. Each dog in the control group received a blank implant (placebo) and each dog in the other four groups received a 6-mg implant containing a slow-release formulation of deslorelin (d-Trp6-Pro 9-des-Gly10?LH-releasing hormone ethylamide). The same four control dogs were used for all hormonal challenges, whereas a different deslorelin-implanted group was used for each challenge. Native GnRH (5 μg kg-1 bodyweight, i.v.) was injected on Days 15, 25, 40 and 100 after implantation, whereas bovine LH (0.5 μg kg-1 bodyweight, i.v.) was injected on Days 16, 26, 41 and 101. On all occasions after Day 25-26 postimplantation, exogenous GnRH and LH elicited higher plasma concentrations of LH and testosterone in control than deslorelin-treated animals (P < 0.05). It was concluded that, in male dogs, implantation of a GnRH superagonist desensitised the pituitary gonadotrophs to GnRH and also led to a desensitisation of the Leydig cells to LH. This explains, at least in part, the profound reduction in the production of androgen and spermatozoa in deslorelin-treated male dogs
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