A growth model of weight preferences, food consumption and public policy

Copyright @ 2013 Brunel University.In this paper we unify existing theories and empirical evidence on the origins of obesity and examine the e¤ects of scal policy on the dynamic evolution of weight. We build a dynamic general equilibrium growth model, with two sectors, one producing food and the other producing a composite consumption good. Weight is a function of rational choice as well as labor allocation between the two sectors. By estimating utility from weight and calibrating the US economy we show that (i) technological advances in agriculture decrease food prices and increase weight but not necessarily through higher food consumption but through lower calorie expenditure, (ii) reducing capital taxation, initially depresses weight levels through higher food prices; steady state food consumption decreases due to a price substitution e¤ect but weight soars due to lower calorie expenditure, (iii) reducing taxation on food increases food consumption and weight levels in equilibrium. Labor reallocation towards the less sedentary sector on one hand and higher income on the other function as contradictory forces

Detection of Leishmania infantum by PCR, serology and cellular immune response in a cohort study of Brazilian dogs

The sensitivity and specificity of PCR, serology (ELISA) and lymphoproliferative response to Leishmania antigen for the detection of Leishmania infantum infection were evaluated in a cohort of 126 dogs exposed to natural infection in Brazil. For PCR, Leishmania DNA from bone-marrow was amplified with both minicircle and ribosomal primers. The infection status and time of infection of each dog were estimated from longitudinal data. The sensitivity of PCR in parasite-positive samples was 98%. However, the overall sensitivity of PCR in post-infection samples, from dogs with confirmed infection, was only 68%. The sensitivity of PCR varied during the course of infection, being highest (78–88%) 0–135 days post-infection and declining to around 50% after 300 days. The sensitivity of PCR also varied between dogs, and was highest in sick dogs. The sensitivity of serology was similar in parasite-positive (84%), PCR-positive (86%) and post-infection (88%) samples. The sensitivity of serology varied during the course of infection, being lowest at the time of infection and high (93–100%) thereafter. Problems in determining the specificity of serology are discussed. The sensitivity and specificity of cellular responsiveness were low. These data suggest that PCR is most useful in detecting active or symptomatic infection, and that serology can be a more sensitive technique for the detection of all infected dogs

The limitations of speech control: perceptions of provision of speech-driven environmental controls

This study set out to collect data from assistive technology professionals about their provision of speech-driven environmental control systems. This study is part of a larger study looking at developing a new speech-driven environmental control system

Sanitizing the fortress: protection of ant brood and nest material by worker antibiotics

Social groups are at particular risk for parasite infection, which is heightened in eusocial insects by the low genetic diversity of individuals within a colony. To combat this, adult ants have evolved a suite of defenses to protect each other, including the production of antimicrobial secretions. However, it is the brood in a colony that are most vulnerable to parasites because their individual defenses are limited, and the nest material in which ants live is also likely to be prone to colonization by potential parasites. Here, we investigate in two ant species whether adult workers use their antimicrobial secretions not only to protect each other but also to sanitize the vulnerable brood and nest material. We find that, in both leaf-cutting ants and weaver ants, the survival of the brood was reduced and the sporulation of parasitic fungi from them increased, when the workers nursing them lacked functional antimicrobial-producing glands. This was the case for both larvae that were experimentally treated with a fungal parasite (Metarhizium) and control larvae which developed infections of an opportunistic fungal parasite (Aspergillus). Similarly, fungi were more likely to grow on the nest material of both ant species if the glands of attending workers were blocked. The results show that the defense of brood and sanitization of nest material are important functions of the antimicrobial secretions of adult ants and that ubiquitous, opportunistic fungi may be a more important driver of the evolution of these defenses than rarer, specialist parasites

Interacting Turing-Hopf Instabilities Drive Symmetry-Breaking Transitions in a Mean-Field Model of the Cortex: A Mechanism for the Slow Oscillation

Electrical recordings of brain activity during the transition from wake to anesthetic coma show temporal and spectral alterations that are correlated with gross changes in the underlying brain state. Entry into anesthetic unconsciousness is signposted by the emergence of large, slow oscillations of electrical activity (≲1  Hz) similar to the slow waves observed in natural sleep. Here we present a two-dimensional mean-field model of the cortex in which slow spatiotemporal oscillations arise spontaneously through a Turing (spatial) symmetry-breaking bifurcation that is modulated by a Hopf (temporal) instability. In our model, populations of neurons are densely interlinked by chemical synapses, and by interneuronal gap junctions represented as an inhibitory diffusive coupling. To demonstrate cortical behavior over a wide range of distinct brain states, we explore model dynamics in the vicinity of a general-anesthetic-induced transition from “wake” to “coma.” In this region, the system is poised at a codimension-2 point where competing Turing and Hopf instabilities coexist. We model anesthesia as a moderate reduction in inhibitory diffusion, paired with an increase in inhibitory postsynaptic response, producing a coma state that is characterized by emergent low-frequency oscillations whose dynamics is chaotic in time and space. The effect of long-range axonal white-matter connectivity is probed with the inclusion of a single idealized point-to-point connection. We find that the additional excitation from the long-range connection can provoke seizurelike bursts of cortical activity when inhibitory diffusion is weak, but has little impact on an active cortex. Our proposed dynamic mechanism for the origin of anesthetic slow waves complements—and contrasts with—conventional explanations that require cyclic modulation of ion-channel conductances. We postulate that a similar bifurcation mechanism might underpin the slow waves of natural sleep and comment on the possible consequences of chaotic dynamics for memory processing and learning

Assessment for Learning in International Contexts: exploring shared and divergent dimensions in teacher values and practices

The Assessment for Learning in International Contexts (ALIC) project sought to extend knowledge around teachers’ understandings of Assessment for Learning (AfL). Using a modified version of a survey item devised by James and Pedder (2006) for use with teachers in England, evidence was gathered about the assessment practices that were highly valued by teachers across international contexts. The extent of congruence between these values and teachers’ reported classroom practices was explored and dimensions of teachers’ assessment practices were derived through factor analysis. Whilst there was considerable congruence across the ALIC cohort of teachers and data sets derived from English teachers, particularly with respect to the items that have positive values-practice gaps, there were some interesting differences. Two components were derived from factor analysis, rather than the three derived by James and Pedder (2006). These components were ‘Making learning explicit and promoting learner autonomy’ and ‘Student control of assessment processes’.This is an Accepted Manuscript of an article published by Taylor & Francis in The Curriculum Journal on the 6th of November 2014, available online: http://wwww.tandfonline.com/10.1080/09585176.2014.975732. This version will be under embargo until the 6th of May 2016

(Super)twistors and (super)strings

The Lagrangian formulation of the D=4 bosonic string and superstring in terms of the (super)twistors is considered. The (super)twistor form of the equations of motion is derived and the kappa-symmetry transformation for the supertwistors is given. It is shown that the covariant kappa-symmetry gauge fixation results in the action quadratic in the (super)twistor variables.Comment: LaTeX, 17 page

The Big Pet Diabetes Survey: Perceived Frequency and Triggers for Euthanasia

Current pet diabetes mellitus (DM) treatment necessitates the active daily involvement of owners and can be costly. The current study aimed to investigate the owner population which opts for euthanasia instead of DM treatment. A survey was designed using multiple feedback steps and made available online to veterinarians world-wide. A total of 1192 veterinarians completed the survey and suggested a median one in 10 diabetic pets are euthanased at diagnosis; a further median one in 10 within one year because of lack of success or compliance. Perceived most important motivating factors included “presence concurrent disease” (45% respondents); “costs” (44%); “animal age” (37%); “problems obtaining adequate control” (35%); “pet welfare” (35%); and “impact owner’s lifestyle” (32%). Cats in Canadian (odds ratio (OR) 2.7), Australian (OR 2.3), rural (OR 1.6) and mixed (OR 1.7) practices were more likely to be euthanased because of DM diagnosis, while cats presented to referral/university were less likely to be euthanased (OR 0.6). Dogs were more likely to be euthanased because of DM in Canadian (OR 1.8), rural (OR 1.8) and mixed (OR 1.6) practices. The survey results suggest that benefit exists in improved DM education with emphasis on offering a choice of treatment styles ranging from intense and expensive to hands-off and cheap