Response suppression as a function of a vacation from punishment

Response suppression as function of vacation from punishment in pigeon

Epidemiology of diabetes mellitus among 193,435 cats attending primary-care veterinary practices in England

BACKGROUND: Diabetes mellitus (DM) is a common endocrine disease of cats. The prevalence of DM in cats in England is not well‐defined. HYPOTHESIS/OBJECTIVES: To estimate the prevalence and identify risk factors for DM in a large population of cats attending primary‐care practices. ANIMALS: A cohort of 193,563 cats in the VetCompass Programme attending 118 primary‐care practices in England. METHODS: Cross‐sectional analysis of cohort clinical data. Data were extracted covering September 1st 2009 and August 31st 2014. Period prevalence of DM was calculated. Associations between risk factors and DM were assessed using logistic regression modelling. RESULTS: Of 1,128 DM cases were identified among 194,563 cats (period prevalence 0.58%; 95% confidence interval [CI] 0.54–0.61). Multivariable modelling indicated that Tonkinese (OR 4.1; 95% CI 1.8–9.6; P = .001), Norwegian Forest (odds ratio [OR] 3.5; 95% CI 1.3–9.6; P = .001) and Burmese (OR 3.0; 95% CI 2.0–4.4; P < .001) cats had increased odds of DM compared with crossbred cats. DM odds increased as bodyweight categories increased above 4 kg (P < .001), as cats aged beyond 6 years old (P < .001) and in insured cats (OR 2.0; 95% CI 1.6–2.4; P < .001) but sex was not significantly associated with DM. CONCLUSIONS AND CLINICAL IMPORTANCE: Diabetes mellitus is an important component of the primary‐care practice caseload with 1‐in‐200 cats affected. An increased risk of DM in certain cat breeds supports a genetic predisposition. These results can guide future research and preventative healthcare

Previous high-intensity activity affects lower limb strength ratios

Lower limb strength ratios are important in assessing muscular imbalances. Typically, these ratios are derived from assessment of explosive, maximum effort activities. Such assessment can be functional or isokinetic. The single-effort nature of these assessments does not provide information on imbalance changes after muscular contractions. Any such change could indicate an increased risk of injury after a period of activity, thus raising questions as to the correct procedure of muscle imbalance assessment. Therefore, the aim of the current study was to assess muscle imbalances over maximum effort repeated cycling sprints. Seventeen healthy, physically active young adults (females: n=4, height 1.62±0.03 m, body mass 68.0±6.5 kg; males: n=13, height 1.80±0.06 m, body mass 80.5±13.8 kg) performed five 6-s sprints with 24-s rest interval on a Lode Excalibur bike with torque and power data recorded for each leg. Average, average maximum (average of maximum from each sprint) and peak torque (TAv, TAvM and TP respectively) and power (PAv, PAvM and PP respectively) were obtained for each leg. Ratios of these variables were calculated as . Wilcoxon's test revealed a significantly stronger leg (p<0.05) for all torque and power variables. Friedman's test indicated a significant ratio increase between TAv (11.7±6.8%) and TAvM (4.6±3.0%, p=0.001) and TP (4.1±3.5%, p=0.001), as well as between PAv (8.8±5.0%) and PAvM (4.5±2.9%, p=0.003) and PP (4.2±2.6, p=0.003%) but not between TAvM and TP (p=0.421) or PAvM and PP (p=0.981). The results indicate that high-intensity activity increases lower limb strength imbalance, resulting in different ratios. The authors posit that muscle imbalance assessment activities conducted at rested state may not accurately reflect the true strength difference between limbs, leading to inaccurate training or rehabilitation advice

First-order asymptotic theory for parametric misspecification tests of Garch models

publication-status: Publishedtypes: ArticleFinal version of the article as published in Econometric Theory, vol. 35, issue 2, pp. 364-410. Copyright © Cambridge University Press 2009. Available online at http://journals.cambridge.org/This paper develops a framework for the construction and analysis of parametric misspecification tests for generalized autoregressive conditional heteroskedastic (GARCH) models, based on first-order asymptotic theory. The principal finding is that estimation effects from the correct specification of the conditional mean (regression) function can be asymptotically nonnegligible. This implies that certain procedures, such as the asymmetry tests of Engle and No. (1993, Journal of Finance 48. 1749-1777) and the nonlinearity test of Lundbergh and Terasvirta (2002, Journal of Econometrics 110, 417-435), are asymptotically invalid. A second contribution is the proposed use of alternative tests for asymmetry and/or nonlinearity that, it is conjectured, should enjoy improved power properties. A Monte Carlo study supports the principal theoretical findings and also suggests that the new tests have fairly good size and very good power properties when compared with the Engle and Ng (1993) and Lundbergh and Terasvirta (2002) procedures

A heteroskedasticity robust Breusch-Pagan test for contemporaneous correlation in dynamic panel data models

Working paper dated August 16, 2011This paper proposes a heteroskedasticity-robust Breusch-Pagan test of the null hypothesis of zero cross-section (or contemporaneous) correlation in linear panel data models. The procedure allows for either xed, strictly exogenous and/or lagged de- pendent regressor variables, as well as quite general forms of both non-normality and heteroskedasticity in the error distribution. Whilst the asymptotic validity of the test procedure, under the null, is predicated on the number of time series observations, T, being large relative to the number of cross-section units, N, independence of the cross-sections is not assumed. Across a variety of experimental designs, a Monte Carlo study suggests that, in general (but not always), the predictions from asymptotic the- ory provide a good guide to the finite sample behaviour of the test. In particular, with skewed errors and/or when N=T is not small, discrepancies can occur. However, for all the experimental designs, any one of three asymptotically valid wild bootstrap approximations (that are considered in this paper) gives very close agreement between the nominal and empirical signi cance levels of the test. Moreover, in comparison with wild bootstrap version of the original Breusch-Pagan test (Godfrey and Yamagata, 2011) the corresponding version of the heteroskedasticity-robust Breusch-Pagan test is more reliable. As an illustration, the proposed tests are applied to a dynamic growth model for a panel of 20 OECD countries

Levosimendan for the prevention of acute organ dysfunction in sepsis

BACKGROUND Levosimendan is a calcium-sensitizing drug with inotropic and other properties that may improve outcomes in patients with sepsis. METHODS We conducted a double-blind, randomized clinical trial to investigate whether levosimendan reduces the severity of organ dysfunction in adults with sepsis. Patients were randomly assigned to receive a blinded infusion of levosimendan (at a dose of 0.05 to 0.2 μg per kilogram of body weight per minute) for 24 hours or placebo in addition to standard care. The primary outcome was the mean daily Sequential Organ Failure Assessment (SOFA) score in the intensive care unit up to day 28 (scores for each of five systems range from 0 to 4, with higher scores indicating more severe dysfunction; maximum score, 20). Secondary outcomes included 28-day mortality, time to weaning from mechanical ventilation, and adverse events. RESULTS The trial recruited 516 patients; 259 were assigned to receive levosimendan and 257 to receive placebo. There was no significant difference in the mean (±SD) SOFA score between the levosimendan group and the placebo group (6.68±3.96 vs. 6.06±3.89; mean difference, 0.61; 95% confidence interval [CI], −0.07 to 1.29; P=0.053). Mortality at 28 days was 34.5% in the levosimendan group and 30.9% in the placebo group (absolute difference, 3.6 percentage points; 95% CI, −4.5 to 11.7; P=0.43). Among patients requiring ventilation at baseline, those in the levosimendan group were less likely than those in the placebo group to be successfully weaned from mechanical ventilation over the period of 28 days (hazard ratio, 0.77; 95% CI, 0.60 to 0.97; P=0.03). More patients in the levosimendan group than in the placebo group had supraventricular tachyarrhythmia (3.1% vs. 0.4%; absolute difference, 2.7 percentage points; 95% CI, 0.1 to 5.3; P=0.04). CONCLUSIONS The addition of levosimendan to standard treatment in adults with sepsis was not associated with less severe organ dysfunction or lower mortality. Levosimendan was associated with a lower likelihood of successful weaning from mechanical ventilation and a higher risk of supraventricular tachyarrhythmia. (Funded by the NIHR Efficacy and Mechanism Evaluation Programme and others; LeoPARDS Current Controlled Trials number, ISRCTN12776039.

First light for avian embryos: eggshell thickness and pigmentation mediate variation in development and UV exposure in wild bird eggs

Article first published online: 29 JUL 20141. The avian embryo's development is influenced by both the amount and the wavelength of the light that passes through the eggshell. Commercial poultry breeders use light of specific wavelengths to accelerate embryonic growth, yet the effects of the variably patterned eggshells of wild bird species on light transmission and embryonic development remain largely unexplored. 2. Here, we provide the first comparative phylogenetic analysis of light transmission, through a diverse range of bird eggshells (74 British breeding species), in relation to the eggshell's thickness, permeability, pigment concentration and surface reflectance spectrum (colour). 3. The percentage of light transmitted through the eggshell was measured in the spectral range 250–700 nm. Our quantitative analyses confirm anecdotal reports that eggshells filter the light of the externally coloured shell. Specifically, we detected a positive relationship between surface eggshell reflectance (‘brightness’) and the percentage of light transmitted through the eggshell, and this relationship was strongest at wavelengths in the human-visible blue-green region of the spectra (c. 435 nm). 4. We show that less light passes through thicker eggshells with greater total pigment concentrations. By contrast, permeability (measured as water vapour conductance) did not covary significantly with light transmission. Eggs of closed-nesting species let more light pass through, compared with open nesters. 5. We postulate that greater light transmission is required to assist embryonic development under low light exposure. Importantly, this result provides an ecological explanation for the repeated evolution of immaculate, white- or pale-coloured eggshells in species nesting in enclosed spaces. 6. Finally, we detected correlative support for the solar radiation hypothesis, in that eggshells of bird species with a longer incubation period let significantly less of the potentially harmful, ultraviolet (UV) light pass through the eggshell. In summary, we demonstrate suites of avian eggshell properties, including eggshell structure and pigmentation, which are consistent with an evolutionary pressure to both enhance and protect embryonic development.Golo Maurer, Steven J. Portugal, Mark E. Hauber, Ivan Mikšík, Douglas G. D. Russell and Phillip Casse

Phylogenetic non-independence in rates of trait evolution

Statistical non-independence of species’ biological traits is recognized in most traits under selection. Yet, whether or not the evolutionary rates of such biological traits are statistically non-independent remains to be tested. Here we test the hypothesis that phenotypic evolutionary rates are non-independent, i.e. contain phylogenetic signal, using empirical rates of evolution in three separate traits: body mass in mammals; beak shape in birds; and bite force in amniotes. Specifically, we test whether rates are non-independent throughout the evolutionary history of each tree. We find evidence for phylogenetic signal in evolutionary rates in all three case studies. While phylogenetic signal diminishes deeper in time, this is reflective of statistical power owing to small sample and effect sizes. When effect size is large, e.g., owing to the presence of fossil tips, we detect high phylogenetic signals even in deeper time slices. Thus, we recommend that rates be treated as being non-independent throughout the evolutionary history of the group of organisms under study, and any summaries or analyses of rates through time – including associations of rates with traits – need account for the undesired effects of shared ancestry

Orientation of the Stripe Formed by the Two-Dimensional Electrons in Higher Landau Levels

Effect of periodic potential on the stripe phase realized in the higher Landau levels is investigated by the Hartree-Fock approximation. The period of the potential is chosen to be two to six times of the fundamental period of the stripe phase. It is found that the stripe aligns perpendicularly to the external potential in contrast to a naive expectation and hydrodynamic theory. Charge modulation towards the Wigner crystallization along the stripe is essential for the present unexpected new result.Comment: 5 pages, RevTex, two figures included in the tex

Anisotropy and periodicity in the density distribution of electrons in a quantum-well

We use low temperature near-field optical spectroscopy to image the electron density distribution in the plane of a high mobility GaAs quantum well. We find that the electrons are not randomly distributed in the plane, but rather form narrow stripes (width smaller than 150 nm) of higher electron density. The stripes are oriented along the [1-10 ] crystal direction, and are arranged in a quasi-periodic structure. We show that elongated structural mounds, which are intrinsic to molecular beam epitaxy, are responsible for the creation of this electron density texture.Comment: 10 pages, 3 figure