The effect of the GLP-1 analogue Exenatide on functional connectivity within an NTS-based network in women with and without obesity.

ObjectiveThe differential effect of GLP-1 agonist Exenatide on functional connectivity of the nucleus tractus solitaries (NTS), a key region associated with homeostasis, and on appetite-related behaviours was investigated in women with normal weight compared with women with obesity.MethodsFollowing an 8-h fast, 19 female subjects (11 lean, 8 obese) participated in a 2-d double blind crossover study. Subjects underwent functional magnetic resonance imaging at fast and 30-min post subcutaneous injection of 5 μg of Exenatide or placebo. Functional connectivity was examined with the NTS. Drug-induced functional connectivity changes within and between groups and correlations with appetite measures were examined in a region of interest approach focusing on the thalamus and hypothalamus.ResultsWomen with obesity reported less hunger after drug injection. Exenatide administration increased functional connectivity of the left NTS with the left thalamus and hypothalamus in the obese group only and increased the correlation between NTS functional connectivity and hunger scores in all subjects, but more so in the obese.ConclusionsObesity can impact the effects of Exenatide on brain connectivity, specifically in the NTS and is linked to changes in appetite control. This has implications for the use of GLP-1 analogues in therapeutic interventions

Sex differences in the influence of body mass index on anatomical architecture of brain networks.

Background/objectivesThe brain has a central role in regulating ingestive behavior in obesity. Analogous to addiction behaviors, an imbalance in the processing of rewarding and salient stimuli results in maladaptive eating behaviors that override homeostatic needs. We performed network analysis based on graph theory to examine the association between body mass index (BMI) and network measures of integrity, information flow and global communication (centrality) in reward, salience and sensorimotor regions and to identify sex-related differences in these parameters.Subjects/methodsStructural and diffusion tensor imaging were obtained in a sample of 124 individuals (61 males and 63 females). Graph theory was applied to calculate anatomical network properties (centrality) for regions of the reward, salience and sensorimotor networks. General linear models with linear contrasts were performed to test for BMI and sex-related differences in measures of centrality, while controlling for age.ResultsIn both males and females, individuals with high BMI (obese and overweight) had greater anatomical centrality (greater connectivity) of reward (putamen) and salience (anterior insula) network regions. Sex differences were observed both in individuals with normal and elevated BMI. In individuals with high BMI, females compared to males showed greater centrality in reward (amygdala, hippocampus and nucleus accumbens) and salience (anterior mid-cingulate cortex) regions, while males compared to females had greater centrality in reward (putamen) and sensorimotor (posterior insula) regions.ConclusionsIn individuals with increased BMI, reward, salience and sensorimotor network regions are susceptible to topological restructuring in a sex-related manner. These findings highlight the influence of these regions on integrative processing of food-related stimuli and increased ingestive behavior in obesity, or in the influence of hedonic ingestion on brain topological restructuring. The observed sex differences emphasize the importance of considering sex differences in obesity pathophysiology

Smoke and fire dynamics in atria and large enclosures: An overview

The proliferation of atria within modern large buildings is relatively recent. An atrium can be defined as a large open space connecting two or more storeys. Atria are important architectonical features since the 60's and can be found, among others, in shopping centres, office buildings and high-rise buildings, airports, stations and sports centres. However, the atrium represents an innovative, complex and non conventional architectonical element that can lead to fire environments diverging significantly from those in conventional compartments used in the development of current codes and standards. They are a source of discussion in the fire safety community because smoke can easily spread from one floor to another making the traditional methodologies for compartmentation of little or null effect. The design of smoke management in atria has been based on prescriptive codes since the 70's. It was not until the mid 80's that the phenomena started to be the objective of both experimental and numerical studies. It is because of the subsequent improved understanding on fire dynamics and smoke management together with the increased computing power available nowadays, that there is a progressive movement from prescriptive-based to performance-based codes which is also chaning the way atria are designed. The aim of the present work is to provide a broad overview of the current state-of-the-art of fires in atria. A brief introduction to the characteristics and types of atrium structures is presented first. Then, a description of the fire dynamics as well as the main safety problems that arise in case of fire are considered. A historical discussion of the research, including experimental and numerical studies, is presented, and current design methodologies and fire safety strategies are discussed. The final part of the overview addresses the international tendencies towards the introduction of performance-based fire protection codes. This overview highlights the need for further experimental studies and validations of numerical simulations for a wider range of fire conditions. © 2010 by Nova Science Publishers, Inc. All rights reserved

Global mode analysis of axisymmetric bluff-body wakes: Stabilization by base bleed

International audienceThe flow around a slender body with a blunt trailing edge is unstable in most situations of interest. Usually the flow instabilities are generated within the wake behind the bluff body, inducing fluctuating forces and introducing the possibility of resonance mechanisms with modes of the structure. Base bleed is a simple and well-known means of stabilizing the wake. In the present research, we investigate the global instability properties of the laminar-incompressible flow that develops behind a cylinder with sharp edges and axis aligned with the free stream using a spectral domain decomposition method. In particular, we describe the flow instability characteristics as a function of the Reynolds number, Re=?W8D/µ, and the bleed coefficient, defined as the bleed-to-free-stream velocity ratio, Cb=Wb/W8, where D is the diameter of the body and ? and µ the density and viscosity of the free stream, respectively. For a truncated cylinder of aspect ratio L/D=5, where L is the length of the body, our calculations reveal the presence of a first steady bifurcation in the wake at Re?391, as well as a second oscillatory one at Re?715 with an associated Strouhal number St?0.0905 for the most unstable azimuthal mode {pipe}m{pipe}=1. In addition, we report the existence of two critical values of the bleed coefficient Cb1*(Re,{pipe}m{pipe}) and Cb2*(Re,{pipe}m{pipe}) < Cb1*, which vary with the aspect ratio of the body, needed to stabilize both the first and second bifurcations in the range of Reynolds numbers under study, 0=Re=2200. Finally, the numerical results for the oscillatory mode obtained for a bulletlike body of aspect ratio L/D=2 without base bleed are compared with experiments performed in a wind tunnel using hot-wire anemometry, showing the limitations of using an axisymmetric basic flow at Reynolds numbers higher than the critical one corresponding to the first steady bifurcation in the global stability analysis. © 2009 American Institute of Physics

The costs of fusion in smart camera networks

ABSTRACT The choice of the most suitable fusion scheme for smart camera networks depends on the application as well as on the available computational and communication resources. In this paper we discuss and compare the resource requirements of five fusion schemes, namely centralised fusion, flooding, consensus, token passing and dynamic clustering. The Extended Information Filter is applied to each fusion scheme to perform target tracking. Token passing and dynamic clustering involve negotiation among viewing nodes (cameras observing the same target) to decide which node should perform the fusion process whereas flooding and consensus do not include this negotiation. Negotiation helps limiting the number of participating cameras and reduces the required resources for the fusion process itself but requires additional communication. Consensus has the highest communication and computation costs but it is the only scheme that can be applied when not all viewing nodes are connected directly and routing tables are not available

Development of conversation in toddlers: The role of maternal input

Abstract only availableOne of the most important human skills is the ability to engage in conversation. This includes our ability to initiate topics, take turns appropriately, and respond contingently to a partner's utterances. While we know that children learn these skills, a clear understanding of the steps they take in developing them and of the factors that may influence the course and rate of development is currently lacking. The present longitudinal study uses language samples collected from 45 mother-child dyads to analyze how children between the ages of 20 and 30 months develop conversation. In addition, it examines the impact of maternal education on this development. Results indicate that the nature of mothers' and children's contributions to discourse change with age. Children become more adept at contingent responding, and the percent of consecutive utterances and topic initiations made by mothers decreases as the children age. Maternal education does not significantly affect the way mothers and children converse in this study. These results suggest that turn-taking between mother and child increases as mothers respond to their children's growing conversational competence. At least within this population, maternal education does not affect the way that the mothers respond. Future studies might examine a wider range of maternal education and investigate whether children's conversational development depends substantially on their language skills.MU Undergraduate Research Scholars Progra

Genome of Mycoplasma haemofelis, unraveling its strategies for survival and persistence

Mycoplasma haemofelis is a mycoplasmal pathogen (hemoplasma) that attaches to the host's erythrocytes. Distributed worldwide, it has a significant impact on the health of cats causing acute disease and, despite treatment, establishing chronic infection. It might also have a role as a zoonotic agent, especially in immunocompromised patients. Whole genome sequencing and analyses of M. haemofelis strain Ohio2 was undertaken as a step toward understanding its survival and persistence. Metabolic pathways are reduced, relying on the host to supply many of the nutrients and metabolites needed for survival. M. haemofelis must import glucose for ATP generation and ribose derivates for RNA/DNA synthesis. Hypoxanthine, adenine, guanine, uracil and CMP are scavenged from the environment to support purine and pyrimidine synthesis. In addition, nicotinamide, amino acids and any vitamins needed for growth, must be acquired from its environment. The core proteome of M. haemofelis contains an abundance of paralogous gene families, corresponding to 70.6% of all the CDSs. This "paralog pool" is a rich source of different antigenic epitopes that can be varied to elude the host's immune system and establish chronic infection. M. haemofelis also appears to be capable of phase variation, which is particularly relevant to the cyclic bacteremia and persistence, characteristics of the infection in the cat. The data generated herein should be of great use for understanding the mechanisms of M. haemofelis infection. Further, it will provide new insights into its pathogenicity and clues needed to formulate media to support the in vitro cultivation of M. haemofelis