Energy-Momentum Tensor of Particles Created in an Expanding Universe

We present a general formulation of the time-dependent initial value problem for a quantum scalar field of arbitrary mass and curvature coupling in a FRW cosmological model. We introduce an adiabatic number basis which has the virtue that the divergent parts of the quantum expectation value of the energy-momentum tensor are isolated in the vacuum piece of , and may be removed using adiabatic subtraction. The resulting renormalized is conserved, independent of the cutoff, and has a physically transparent, quasiclassical form in terms of the average number of created adiabatic `particles'. By analyzing the evolution of the adiabatic particle number in de Sitter spacetime we exhibit the time structure of the particle creation process, which can be understood in terms of the time at which different momentum scales enter the horizon. A numerical scheme to compute as a function of time with arbitrary adiabatic initial states (not necessarily de Sitter invariant) is described. For minimally coupled, massless fields, at late times the renormalized goes asymptotically to the de Sitter invariant state previously found by Allen and Folacci, and not to the zero mass limit of the Bunch-Davies vacuum. If the mass m and the curvature coupling xi differ from zero, but satisfy m^2+xi R=0, the energy density and pressure of the scalar field grow linearly in cosmic time demonstrating that, at least in this case, backreaction effects become significant and cannot be neglected in de Sitter spacetime.Comment: 28 pages, Revtex, 11 embedded .ps figure

Low density lipoprotein quality and discordance with apolipoprotein B in intensively controlled Type 1 diabetes: Any relationship with nutrition?

Type 1 diabetes (T1D) is partly characterised by a higher prevalence of cardiovascular disease (CVD). Despite low density lipoprotein cholesterol (LDL-C) being a commonly treated target, apolipoprotein B (Apo B) has been shown to be a superior predictor of CVD and discordance between these two markers may predispose patients to altered risk(1). The distribution of LDL-C also contributes to these risks, with LDL III & IV fractions possessing greater atherogenic potential(2). Few studies have investigated LDL-C quality and its discordance with Apo B in relation to the nutritional intake of patients with intensively controlled Type 1 diabetes. The aim of this study was to address this dearth of research. Following ethical approval and informed consent 28 patients (32 % male; 68 % female) (mean age 48 ± 15) were asked to complete a food frequency questionnaire (FFQ), donate a sample of blood and allow the authors access to their medical records to determine HbA1c. The initial FFQ responses were processed using FETA software. The blood sample was analysed for LDL-C, constituent subfractions and Apo B. All data were interrogated using descriptive statistics. Dichotomous dependent variables pertaining to LDL-C and Apo B were compared using McNemar’s test and correlations between dietary variables were determined with Spearman’s rho test. Significant differences were shown between LDL-C categories when compared to Apo B (p = 0·039) and the majority of patients (46·4 %) presented LDL-C >2·0 mmol/L and Apo B >80 mg/dL (Fig. 1). Although not discordant, these findings still suggest an increased risk according to recommendations(3). Closer inspection of results revealed that individuals with raised LDL-C typically had an abundance of LDL I & II fractions which may somewhat reduce this risk (Fig. 2). Spearman’s correlation applied to the whole population produced no relationship between diet and LDL-C or Apo B; however, when focussing on the predominant ‘at risk’ cluster significant and strong relationships between LDL-C and total carbohydrate (R2 = 0·835; p = <0·001) and sucrose (R2 = 0·758; p = 0·003) were found. No hypoglycaemia data were collected and the authors tentatively speculate that these relationships may be a consequence of its treatment. In the light of the small sample size a further more comprehensive investigation with an appropriately powered sample would be beneficial

An investigation into the eating behaviours of adult patients with Type 1 diabetes using continuous subcutaneous insulin infusion therapy compared to those using multiple daily injections

Multiple daily injections (MDI) are an intensive method of administering an external source of basal and bolus insulin for patients with Type 1 diabetes (T1D). This therapy requires 4-5 injections per day, is regarded as an effective method of achieving glycaemic control and is commonly used. If HbA1c remains above 8.5% or if a patient is experiencing disabling hypoglycaemic episodes continuous subcutaneous insulin infusion (CSII) therapy may be recommended1. CSII provides flexible insulin administration via a small, electronic pump unit and has been associated with various benefits when compared to MDI, including increased glycaemic control, reduced occurrence of hypoglycaemia and improvements in the dawn phenomenon1,2. Furthermore, the flexible nature of CSII potentially allows patients to enjoy a liberalised diet compared to those using the relatively structured MDI regime2. There is a dearth of evidence focussing on the eating behaviours of these patients and research into this area would be useful to inform both treatment and the evaluation of risk. Following ethical approval and informed consent patients with T1D using either CSII or MDI from the Royal Liverpool Hospital were asked to complete an EPIC-Norfolk food frequency questionnaire (FFQ). Responses were processed using FETA software and demographic data from participants’ medical records were added. All data were initially analysed using descriptive statistics. Any data not normally distributed were transformed logarithmically and t-tests and Mann-Whitney-U-tests were then carried out. The study population consisted of 60 patients (33.3% male, 66.7% female) with 40 using CSII and 20 using MDI and a mean age of 48±16 years. The majority of patients were overweight or obese (71.4% CSII, 57.1% MDI), however energy intake was below the reference nutrient intake (RNI) for both CSII and MDI groups. Patients using both CSII and MDI consumed protein above the RNI for males and females3. Despite this protein contributed towards 18.6% of the daily energy intake of patients using CSII and 19.0% of those using MDI. Total carbohydrate (CHO) consumption was below the RNI of 50%, however it should be noted that consumption of total sugars was above the RNI for males and females in both groups. This may be partly explained by the consumption of fruit which was also higher in those using CSII. Total fat and saturated fat consumption was marginally above the RNI’s. There were no statistically significant associations between any variables and the diets of the two populations appear largely homogenous, despite slight deviations of some nutrients from RNI’s. Further analysis of total energy, protein and CHO quality is warranted

Out-of-equilibrium evolution of scalar fields in FRW cosmology: renormalization and numerical simulations

We present a renormalized computational framework for the evolution of a self-interacting scalar field (inflaton) and its quantum fluctuations in an FRW background geometry. We include a coupling of the field to the Ricci scalar with a general coupling parameter $\xi$. We take into account the classical and quantum back reactions, i.e., we consider the the dynamical evolution of the cosmic scale factor. We perform, in the one-loop and in the large-N approximation, the renormalization of the equation of motion for the inflaton field, and of its energy momentum tensor. Our formalism is based on a perturbative expansion for the mode functions, and uses dimensional regularization. The renormalization procedure is manifestly covariant and the counter terms are independent of the initial state. Some shortcomings in the renormalization of the energy-momentum tensor in an earlier publication are corrected. We avoid the occurence of initial singularities by constructing a suitable class of initial states. The formalism is implemented numerically and we present some results for the evolution in the post-inflationary preheating era.Comment: 44 pages, uses latexsym, 6 pages with 11 figures in a .ps fil

In vitro neuroprotective activities of two distinct probiotic consortia

Neurodegeneration has been linked to changes in the gut microbiota and this study compares the neuroprotective capability of two bacterial consortia, known as Lab4 and Lab4b, using the established SH-SY5Y neuronal cell model. Firstly, varying total antioxidant capacities (TAC) were identified in the intact cells from each consortia and their secreted metabolites, referred to as conditioned media (CM). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Crystal Violet (CV) assays of cell viability revealed that Lab4 CM and Lab4b CM could induce similar levels of proliferation in SH-SY5Y cells and, despite divergent TAC, possessed a comparable ability to protect undifferentiated and retinoic acid-differentiated cells from the cytotoxic actions of rotenone and undifferentiated cells from the cytotoxic actions of 1-methyl-4-phenylpyridinium iodide (MPP+). Lab4 CM and Lab4b CM also had the ability to attenuate rotenone-induced apoptosis and necrosis with Lab4b inducing the greater effect. Both consortia showed an analogous ability to attenuate intracellular reactive oxygen species accumulation in SH-SY5Y cells although the differential upregulation of genes encoding glutathione reductase and superoxide dismutase by Lab4 CM and Lab4b CM, respectively, implicates the involvement of consortia-specific antioxidative mechanisms of action. This study implicates Lab4 and Lab4b as potential neuroprotective agents and justifies their inclusion in further in vivo studies

The influence of continuous subcutaneous insulin infusion therapy vs. multiple daily injections upon the diet of those with Type 1 diabetes: A food diary investigation

There exist a number of therapeutic options for the management of Type 1 diabetes (T1D). Multiple daily injections (MDI) are one such treatment and involve 4-5 daily subcutaneous injections of insulin. This frequently used approach is widely regarded as an effective method of controlling glycaemia; however, if a patient continues to suffer disabling episodes of hypoglycaemia, or if HbA1c remains above 8.5% continuous subcutaneous insulin infusion (CSII) may instead be recommended1. This therapy employs a small programmable pump device to facilitate the administration of insulin to the patient via a cannula. Various advantages of CSII have been documented compared to MDI, including improvements in glycaemic control and reduced incidence of both hypoglycaemia and the dawn phenomenon. An additional attribute, characterised by the flexible nature of the therapy, is that a liberalised diet may be enjoyed by patients, which in turn may infer potential nutrition and quality of life aberrations. This phenomenon is surprisingly under researched and further investigations to inform both treatment and risk would therefore be beneficial. Following ethical approval and informed consent patients with T1D using either CSII or MDI from the Royal Liverpool Hospital were asked to complete a 5 day weighed food diary. Dietplan 6 software was used to process the responses and demographic data from participants’ medical records were added to the dataset. All data were then interrogated using descriptive statistics and any non-normal data were transformed logarithmically before further enquiry with t-tests or analysed non-parametrically with Mann-Whitney-U-tests. The sample comprised of 20 patients (35% male, 65% female) with 11 using CSII and 9 using MDI. The patients’ mean age was 49±16 years and the majority were overweight or obese (72.7% CSII, 55.6% MDI). Nutrient Amount per day (CSII group) Amount per day (MDI group) % energy intake per day (CSII group) % energy intake per day (MDI group) Energy 1866.6 Kcal 2110.5 Kcal N/A N/A Protein 69.0 g/day 89.9 g/day 14.8 17.0 Total CHO 232.3 g/day 251.8 g/day 46.7 44.7 Total sugars 99.8 g/day 88.6 g/day 20.0 15.7 Total fat 73.5 g/day 80.1 g/day 35.4 34.2 Saturated fat 31.6 g/day 29.8 g/day 15.2 12.7 Table. Selected food diary results from patients using CSII and MDI compared to reference nutrient intakes. Results showed mean energy intake was below the reference nutrient intake (RNI) for the CSII group; potentially suggestive of underreporting (Table)3. Patients using both CSII and MDI consumed protein above the RNI; however, this macronutrient contributed towards 14.8% of the daily energy intake of patients using CSII and 17.0% of those using MDI3. Total carbohydrate (CHO) consumption was below the RNI of 50%; however, it should be noted that consumption of total sugars was above the RNI for males and females in both groups4. Previous research by the authors suggesting habitual fruit consumption, particularly in those using CSII, may explain this5. Total fat and saturated fat consumption was mostly synonymic with RNI’s. Although no statistically significant associations were seen between any of the variables and the diets of the two populations appeared largely homogenous it is reassuring that no detrimental changes occurred. Despite this further analysis of total energy, protein and CHO quality is warranted

Testing timed systems modeled by stream X-machines

Stream X-machines have been used to specify real systems where complex data structures. They are a variety of extended finite state machine where a shared memory is used to represent communications between the components of systems. In this paper we introduce an extension of the Stream X-machines formalism in order to specify systems that present temporal requirements. We add time in two different ways. First, we consider that (output) actions take time to be performed. Second, our formalism allows to specify timeouts. Timeouts represent the time a system can wait for the environment to react without changing its internal state. Since timeous affect the set of available actions of the system, a relation focusing on the functional behavior of systems, that is, the actions that they can perform, must explicitly take into account the possible timeouts. In this paper we also propose a formal testing methodology allowing to systematically test a system with respect to a specification. Finally, we introduce a test derivation algorithm. Given a specification, the derived test suite is sound and complete, that is, a system under test successfully passes the test suite if and only if this system conforms to the specification

Nutraceuticals in the prevention and treatment of Atherosclerosis

Objectives: To investigate the effects of nutraceuticals on key processes associated with atherosclerosis in vitro and in vivo. Background: Atherosclerosis is an inflammatory disease of the vasculature in which macrophages play key roles at all stages and represent promising therapeutic targets. Unfortunately, current therapies against atherosclerosis are not fully effective and associated with other issues such as adverse side effects. In addition, there have been many failures on pharmaceutical agents identified from drug discovery programs. Nutraceuticals represent promising alternatives in the prevention and treatment of atherosclerosis but requires a thorough understanding of their actions together with the underlying mechanisms. The purpose of this study was to address this with emphasis on key macrophage processes associated with atherosclerosis. Methods: A combination of macrophage cell lines and primary cultures were used with gene expression analysed by atherosclerosis profiler arrays and real time quantitative PCR. Foam cell formation was investigated by following the uptake of fluorescently labeled modified LDL, intracellular lipid profiling and cholesterol efflux assays. Inflammasome activation was evaluated by following the release of interleukin (IL)-1beta using an ELISA and ROS production using a kit from Abcam. The effects in vivo were analysed in C57BL/6 mice fed a high fat diet. Results: The studies focused on polyphenols, flavanols and omega-6 polyunsaturated fatty acids. These either inhibited or had no effect on several key macrophage processes associated with atherosclerosis such as pro-inflammatory gene expression, the uptake of modified LDL, macropinocytosis, ROS production and the activation of the inflammasome. In addition, where analysed, the nutraceutical inhibited several atherosclerosis-associated markers in mice fed a high fat diet. The mechanisms underlying such actions will be presented. Conclusions: The studies provide new insights into the beneficial actions of nutraceuticals in atherosclerosis

Understanding young people's transitions in university halls through space and time

This article contributes to the theoretical discussion about young people's transitions through space and time. Space and time are complex overarching concepts that have creative potential in deepening understanding of transition. The focus of this research is young people's experiences of communal living in university halls. It is argued that particular space-time concepts draw attention to different facets of experience and in combination deepen the understanding of young people's individual and collective transitions. The focus of the article is the uses of the space-time concepts 'routine', 'representation', 'rhythm' and 'ritual' to research young people's experiences. The article draws on research findings from two studies in the North of England. © 2010 SAGE Publications