2,638 research outputs found

    A Small Target Neutrino Deep-Inelastic Scattering Experiment at the First Muon Collider

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    Several different scenarios for neutrino scattering experiments using a neutrino beam from the muon collider complex are discussed. The physics reach of a neutrino experiment at the front end of a muon collider is shown to extend far beyond that of current neutrino experiments, since the high intensity neutrino beams one would see at the muon collider allow for a large flexibility in choosing neutrino targets. Measurements of quark spin, A-dependence of the structure function xF3xF_3 and neutral current chiral couplings to quarks are outlined.Comment: 7 pages, 2 figures, to appear in the proceedings of the Workshop on Physics at the First Muon Collider and at the Front End of a Muon Collider, November 1997, Fermila

    Accounting Standards, Information Flow, and Firm Investment Behavior

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    We present a description of two different accounting regimes that govern reporting practice in most developed countries. 'One-book' countries, e.g. Germany, use their tax books as the basis for financial reporting and 'two-book' countries, e.g. the United States, keep the books largely separate. We derive a structural model and formalize a testable implication of our discussion: firms in one-book countries may be reluctant to claim some tax benefits if reductions in taxable income may be misinterpreted by financial market participants as signals of lower profitability. Econometric estimates suggest that accounting regime differences play an important role in describing domestic investment patterns both within and across countries.

    At Issue: Students Must Understand Both Theory and Practice

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    Bioresorbable Polylactide Interbody Implants in an Ovine Anterior Cervical Discectomy and Fusion Model: Three-Year Results

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    Study Design. In vivo study of anterior discectomy and fusion using a bioresorbable 70:30 poly(l-lactide-co-d,l-lactide) interbody implant in an ovine model. Objective. To evaluate the efficacy of the polylactide implant to function as an interbody fusion device, and to assess the tissue reaction to the material during the resorption process. Summary of Background Data. The use of polylactide as a cervical interbody implant has several potential advantages when compared with traditional materials. Having an elastic modulus very similar to bone minimizes the potential for stress shielding, and as the material resorbs additional loading is transferred to the developing fusion mass. Although preclinical and clinical studies have demonstrated the suitability of polylactide implants for lumbar interbody fusion, detailed information on cervical anterior cervical discectomy and fusion (ACDF) with polylactide devices is desirable. Methods. Single level ACDF was performed in 8 skeletally mature ewes. Bioresorbable 70:30 poly (l-lactide-co-d,l-lactide) interbody implants packed with autograft were used with single-level metallic plates. Radiographs were made every 3 months up to 1 year, and yearly thereafter. The animals were killed at 6 months (3 animals), 12 months (3 animals), and 36 months (2 animals). In addition to the serial plain radiographs, the specimens were evaluated by nondestructive biomechanical testing and undecalcified histologic analysis. Results. The bioresorbable polylactide implants were effective in achieving interbody fusion. The 6-month animals appeared fused radiographically and biomechanically, whereas histologic sections demonstrated partial fusion (in 3 of 3 animals). Radiographic fusion was confirmed histologically and biomechanically at 12 months (3 of 3 animals) and 36 months (2 of 2 animals). A mild chronic inflammatory response to the resorbing polylactide implant was observed at both 6 months and 12 months. At 36 months, the operative levels were solidly fused and the implants were completely resorbed. No adverse tissue response was observed in any animal at any time period. Conclusion. Interbody fusion was achieved using bioresorbable polylactide implants, with no evidence of implant collapse, extrusion, or adverse tissue response to the material. The use of polylactide as a cervical interbody device appears both safe and effective based on these ACDF animal model results

    Microcanonical treatment of black hole decay at the Large Hadron Collider

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    This study of corrections to the canonical picture of black hole decay in large extra dimensions examines the effects of back-reaction corrected and microcanonical emission at the LHC. We provide statistical interpretations of the different multiparticle number densities in terms of black hole decay to standard model particles. Provided new heavy particles of mass near the fundamental Planck scale are not discovered, differences between these corrections and thermal decay will be insignificant at the LHC.Comment: small additions and clarifications, format for J. Phys.

    The Effects of Physical Activity on Hepatic Lipid Metabolism During Weight-Loss

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    Non-alcoholic fatty liver disease (NAFLD) develops as a result of physical inactivity and overnutrition. Changing dietary behaviors and increasing physical activity are common strategies used for weight-loss; however, it remains unclear what additional benefits are provided by incorporating physical activity in a weight-loss program for the treatment of NAFLD. The purpose of this study was to determine how physical activity reduces hepatic steatosis and changes the expression of hepatic lipogenic genes during weight-loss. Male C57BL/6 mice were fed either a low-fat (LFD; 10% kcal fat) or high-fat (HFD; 60% kcal fat) diet for 10-weeks. Following 10-weeks, the HFD group was randomly assigned to either a LFD (Diet) or LFD with physical activity (Diet+PA) to induce weight-loss for 8-weeks. After 8-weeks of weight-loss, reductions in body and liver mass were observed in both Diet and Diet+PA groups (see Table 1.). Interestingly, the Diet+PA group lost significantly (P\u3c0.05) more body mass than the Diet group. Reductions in body mass and HOMA-IR in the Diet and Diet+PA groups were matched by reductions in hepatic triglyceride levels. In the Diet+PA group, liver triglyceride and cholesterol levels were significantly (P\u3c0.05) lower than all other groups. The greater reduction in hepatic triglyceride levels from physical activity was due to significant (P\u3c0.05) reductions in the expression of lipogenic FASN and SCD-1 mRNA. Interestingly, physical activity did not alter fatty acid uptake or fatty acid oxidation as observed with CD36 and CPT-1a mRNA levels, respectively. Based on these findings, the addition of physical activity to a diet-induced weight-loss intervention provides a more effective approach for the treatment of NAFLD than dieting alone. Table 1. Whole body and hepatic metabolic characteristics following weight-loss. Variables LFD (n=12) HFD (n=12) Diet (n=12) Diet+PA (n=12) Body mass (g) 30.2 ± 1.1 48.8 ± 0.5* 30.3 ± 0.7† 26.1 ± 0.3*,†,‡ Liver mass (g) 1.2 ± 0.1 2.9 ± 0.2* 1.2 ± 0.1† 1.2 ± 0.1† Triglyceride (mg/dL) 99.4 ± 8.7 96.7 ± 5.5 88.3 ± 6.1 88.4 ± 4.8 Cholesterol (mg/dL) 153.5 ± 10.1 246.0 ± 8.7* 148.2 ± 15.5† 127.6 ± 4.7*,† HOMA-IR 22.9 ± 1.2 187.3 ± 7.5* 19.4 ± 8.8† 25.3 ± 10.5† Liver Tg (mg/mg tissue) 1.18 ± 0.14 2.53 ± 0.05* 0.96 ± 0.15† 0.58 ± 0.07*,†,‡ Liver Chol (μg/mg tissue) 437.0 ± 43.0 585.2 ± 54.4* 527.0 ± 56.5 324.0 ± 27.3*,†,‡ FASN mRNA 1.00 ± 0.20 1.90 ± 0.34* 2.10 ± 0.54* 0.46 ± 0.11*,†,‡ CD36/FAT mRNA 1.00 ± 0.22 0.19 ± 0.20* 0.97 ± 0.10† 0.80 ± 0.04† SCD-1 mRNA 1.00 ± 0.28 1.94 ± 0.83* 0.76 ± 0.13† 0.44 ± 0.05*,†,‡ CPT-1a mRNA 1.00 ± 0.18 0.74 ± 0.04* 0.62 ± 0.08* 0.73 ± 0.05* Note. Data are presented as mean ± SEM.*Significantly (P\u3c0.05) different than LFD; †significantly (P\u3c0.05) different than HFD; ‡significantly (P\u3c0.05) different than Diet

    Skull morphology diverges between urban and rural populations of red foxes mirroring patterns of domestication and macroevolution

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    Human activity is drastically altering the habitat use of natural populations. This has been documented as a driver of phenotypic divergence in a number of wild animal populations. Here, we show that urban and rural populations of red foxes (Vulpes vulpes) from London and surrounding boroughs are divergent in skull traits. These changes are primarily found to be involved with snout length, with urban individuals tending to have shorter and wider muzzles relative to rural individuals, smaller braincases and reduced sexual dimorphism. Changes were widespread and related to muscle attachment sites and thus are likely driven by differing biomechanical demands of feeding or cognition between habitats. Through extensive sampling of the genus Vulpes, we found no support for phylogenetic effects on skull morphology, but patterns of divergence found between urban and rural habitats in V. vulpes quantitatively aligned with macroevolutionary divergence between species. The patterns of skull divergence between urban and rural habitats matched the description of morphological changes that can occur during domestication. Specifically, urban populations of foxes show variation consistent with ‘domestication syndrome’. Therefore, we suggest that occurrences of phenotypic divergence in relation to human activity, while interesting themselves, also have the potential to inform us of the conditions and mechanisms that could initiate domestication. Finally, this also suggests that patterns of domestication may be developmentally biased towards larger patterns of interspecific divergence

    The Effects of Physical Activity on Markers of Hepatic Inflammation During Weight-Loss

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    Non-alcoholic fatty liver disease (NAFLD) represents a continuum that begins with accumulation of lipid in hepatic cells progressing to hepatic steatosis with inflammation (steatohepatitis), fibrosis, and cirrhosis. Weight-loss using dietary modification and physical activity are common strategies used for the treatment of NAFLD; however, it remains to be determined the effects of physical activity on hepatic inflammation during weight-loss. The purpose of this study was to determine the therapeutic role of physical activity on plasma and hepatic inflammatory markers during weight-loss. Male C57BL/6 mice were fed either a low-fat (LFD; 10% kcal fat) or high-fat (HFD; 60% kcal fat) diet for 10-weeks. Following 10-weeks, the HFD group was randomly assigned to either a LFD (Diet) or LFD with physical activity (Diet+PA) to induce weight loss for 8-weeks. After 8-weeks, reductions in body mass were observed in both Diet and Diet+PA groups (see Table 1.). Interestingly, the Diet+PA group lost significantly (P\u3c0.05) more body mass than the Diet group. Despite significant (P\u3c0.05) reductions in body mass and HOMA-IR, plasma TNF-α remained elevated in the Diet and Diet+PA groups. Moreover, Diet+PA plasma TNF-α was significantly (P\u3c0.05) greater than the HFD obese controls. Elevated plasma TNF-α in the Diet+PA was matched by a greater hepatic expression of IL-1β and IL-6 mRNA when compared to all groups. Interestingly, the expression of TGF-β1 mRNA was significantly (P\u3c0.05) reduced in the Diet+PA when compared to all groups. The elevated plasma TNF-α and expression of IL-1β and IL-6 mRNA are likely due to physical activity. It remains unclear as to the pro-inflammatory effects of physical activity during weight-loss; however, this may be part of a protective adaption to regular exercise. Furthermore, the reduced hepatic TGF-β1 mRNA levels suggest a protective strategy against fibrogenesis in the spectrum of liver disease. Table 1. Whole body and hepatic metabolic characteristics following weight-loss. Variables LFD (n=12) HFD (n=12) Diet (n=12) Diet+PA (n=12) Body mass (g) 30.2 ± 1.1 48.8 ± 0.5* 30.3 ± 0.7† 26.1 ± 0.3*,†,‡ HOMA-IR 22.9 ± 1.2 187.3 ± 7.5* 19.4 ± 8.8† 25.3 ± 10.5† IL-6 (pg/mL) 6.4 ± 0.7 6.2 ± 1.0 5.9 ± 0.9 6.4 ± 0.9 TNF-α (pg/mL) 30.8 ± 6.7 60.6 ± 5.3* 74.0 ± 8.1* 82.5 ± 7.7*,† IL-1β mRNA 1.00 ± 0.51 0.97 ± 0.34 1.20 ± 0.59 2.83 ± 0.62*,†,‡ IL-6 mRNA 1.00 ± 0.45 1.53 ± 0.50 1.16 ± 0.72 2.36 ± 0.55*,†,‡ TNF-α mRNA 1.00 ± 0.09 0.89 ± 0.08 0.94 ± 0.14 0.83 ± 0.06 TGF-β1 mRNA 1.00 ± 0.06 1.02 ± 0.06 1.02 ± 0.10 0.84 ± 0.05† Note. Data are presented as mean ± SEM. *Significantly (P\u3c0.05) different than LFD; †significantly (P\u3c0.05) different than HFD; ‡significantly (P\u3c0.05) different than Diet
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