We consider Wick's theorem for finite temperature and finite volume systems. Working at an operator level with a path ordered approach, we show that contrary to claims in the literature, expectation ...values of normal ordered products can be chosen to be zero and that results obtained are independent of volume. Thus the path integral and operator approaches to finite temperature and finite volume quantum field theories are indeed seen to be identical. The conditions under which normal ordered products have simple symmetry properties are also considered.
Information about the mass spectrum of compact stars can be used to infer cosmological parameters from gravitational waves (GW) in the absence of redshift measurements obtained from electromagnetic ...(EM) observations. This method will be fundamental in measuring and testing cosmology with GWs for current and future ground-based GW detectors where the majority part of sources are detected without an associated EM counterpart. In this proceeding, we will discuss the prospects and limitations of this approach for studying cosmology. We will show that, even when assuming GW detectors with current sensitivities, the determination of the Hubble constant is strongly degenerate with the maximum mass for black hole production. We will discuss how assuming wrong models for the underlying population of black hole events can bias the Hubble constant estimate up to 40\%.
Monocytes cultured in vitro differentiate to a macrophage-like phenotype and undergo functional changes, including reduced capacity for release of TNF-α and the soluble p55 receptor for TNF ...(sTNF-R55) but enhanced capacity for release of the soluble p75 receptor (sTNF-R75). The cytokines IL-4 and IL-10 act on monocytes to suppress the release of pro-inflammatory cytokines, including TNF-α, and to influence the release of sTNF-R. We therefore investigated the influence of differentiation over 15 days in vitro on the spontaneous and LPS- and IFN-γ-induced release of TNF- α and sTNF-R from human monocytes and examined the actions of IL-4 and IL-10 on these. Unstimulated monocytes did not release TNF-α at any stage but released progressively larger amounts of sTNF-R75 with time. LPS-stimulated release of TNF-α declined substantially after the first day and was consistently suppressed by IL-10 and IL-4 but increased by IFN-γ. Monocytes cultured with IL-10 released more sTNF-R75 at all times and expressed more mRNA for TNF-R75 at day 8. LPS stimulation consistently enhanced both spontaneous and IL-10-augmented release of sTNF-R75, whilst IFN-γ co-stimulation consistently suppressed them. The influence of IL-4 on sTNF-R75 release, however, depended qualitatively on both the length of time in culture and on conditions of stimulation. The effects of LPS and IFN-γ on TNF-α and sTNF-R75 release were progressively lost with increasing time in culture in the presence of IL-4. sTNF-R55 was not detectable after the first day of culture under any of these conditions. IL-4, IL-10 and IFN-γ therefore have distinct, but interacting, effects on the balance between TNF-α and sTNF-R75 release by maturing monocytes. These interactions may be relevant to the pathogenesis or treatment of TNF-α-mediated diseases, where sTNF-R may act to neutralize or stabilise TNF, thereby modifying biological activity.
Patients with severe bums are susceptible to infection with Gram-positive organisms including methicillin-resistant Staphylococcus aureus, and often require higher antibiotic dosages compared with ...other patients. This study examined the pharmacokinetics of a single iv dose of teicoplanin (12 mg/kg) in 15 adults and five children with severe burns. Adults were aged 21–82 years with a median total body surface area (TBSA) burn of 30% (range 15–60%). Children were aged 10 months-10 years with median TBSA burn of 15% (10–30%). At 12 h, the median serum teicoplanin concentration was 12.8 mg/L (9.0–27.1 mg/L) in adults and 7.6 mg/L (6.6–10.8 mg/L) in children, (P < 0.01); at 24 h, the corresponding values were 8.3 mg/L (4.6–12.9 mg/L) and 5.2 mg/L (4.2–6.0 mg/L). Using a three-compartment model, the median terminal half life in adults was 114 h (47–278 h). Children fitted a two-compartment model with a terminal half-life of 38 h (21–41 h). The median concentration of teicoplanin in fluid from the burn wound was 60% of the serum antibiotic concentration. A single iv dose of 12 mg/kg of teicoplanin was sufficient to produce therapeutic serum concentrations in burn patients for 24 h, but monitoring of antibiotic levels in serum may be advisable in those with high total clearance, especially children.
Gravitational waves from the coalescence of compact binaries, together with an associated electromagnetic counterpart, are ideal probes of cosmological models. As demonstrated with GW170817, such ...multimessenger observations allow one to use the source as a standard siren, analog of standard candles in conventional astronomy, in order to measure cosmological parameters such as the Hubble constant. No cosmological ladder is needed to estimate the source luminosity distance from the detected gravitational waves. The error on the luminosity distance plays a crucial rôle in the error budget for the inference of the Hubble constant. In this paper, we provide analytic expressions for the statistical errors on the luminosity distance inferred from gravitational wave data as a function of the sky position and the detector network. In particular, we take into account degeneracy in the parameter space of the gravitational waveform showing that in certain conditions on the gravitational-wave detector network and the source sky position it may not be possible to estimate the luminosity distance of the source. Our analytic approximants shows a good agreement with the uncertainties measured with Bayesian samplers and simulated data. We also present implications for the estimation error on the Hubble constant.
Knowledge of the shape of the mass spectrum of compact objects can be used to help break the degeneracy between the mass and redshift of the gravitational wave (GW) sources, and thus can be used to ...infer cosmological parameters in the absence of redshift measurements obtained from electromagnetic observations. In this paper, we study extensively different aspects of this approach, including its computational limits and achievable accuracy. We focus on ground-based detectors with current and future sensitivities, we first perform the analysis of an extensive set of simulated data with a hierarchical Bayesian scheme inferring population and cosmological parameters. We consider a population model (power-law plus Gaussian) which exhibits characteristic scales (extremes of the mass spectrum, presence of an accumulation point) that allows an indirect estimate of the source redshift. Our analysis of this catalog highlights and quantifies the tight interplay between source population and cosmological parameters, as well as the influence of initial assumptions (whether formulated on the source or cosmological parameters). We then validate our results by an "end-to-end" analysis using simulated GW data and posterior samples generated from Bayesian samplers used for GW parameter estimation, thus mirroring the analysis chain used for observational data for the first time in literature. Our results then lead us to re-examine the estimation of \(H_0\) obtained with GWTC-1, and we show explicitly how population assumptions impact the final \(H_0\) result. Our results underline the importance of inferring population and cosmological parameters jointly (and not separately as is often assumed). The only exception, as we discuss, is if an electromagnetic counterpart was to be observed for all the BBH events: then the population assumptions have less impact on the estimation of cosmological parameters.
We study bosonisation in the massive Thirring and sine-Gordon models at finite temperature
T and non-zero fermion chemical potential μ. For that purpose we use both canonical operator and ...path-integral approaches, paying particular attention to the issues of thermal normal ordering and renormalisation. At
T > 0 and
μ = 0, the massive Thirring model bosonises to the sine-Gordon model with the same
T = 0 identification between coupling constants. We prove that not only the partition functions of the two models coincide, as was recently shown, but also that thermal averages of zero-charge operators can be identified. In particular, analysis of the pointsplit regularised fermion current then leads to the thermal equivalence between sine-Gordon kinks and Thirring fermions. At
μ ≠ 0,
T > 0 and working in perturbation theory about the massless Thirring model, we show that the bosonised theory is the sine-Gordon model plus an additional topological term which accounts for the existence of net fermion charge excitations (the fermions or the kinks) in the thermal bath. This result generalises one recently obtained for the massless case, and it is the two-dimensional version of the low-energy QCD chiral Lagrangian at finite baryon density.
BackgroundFetal undernutrition (of which low birth weight is a marker) is implicated in the development of type 2 diabetes. However, there is limited information on the extent to which birth weight ...is related to precursors of type 2 diabetes in childhood, both in individuals and between ethnic groups. We examined the associations between birth weight and precursors of type 2 diabetes in 9-10 year old children and the contribution of ethnic differences in birth weight to ethnic differences in diabetes precursors.MethodsThis investigation was based on the Child Heart and Health Study in England, a cross-sectional study of anthropometric and fasting metabolic markers (insulin, glucose, HbA1c, urate, C-reactive protein and lipids) in 9-10 year-old children predominantly of South Asian, black African-Caribbean and white European origin. Birth weight was obtained from a combination of birth records, Office for National Statistics data, maternity databases and parental recall. Associations between cardiometabolic risk markers and birth weight were estimated using multilevel linear regression adjusted for age, sex, ethnic group and school (fitted as a random effect).ResultsBirth weight was available for 3744 of 5004 (75%) study participants. Birth weight was inversely associated with urate in unadjusted analyses. After adjustment for height, lower birth weight was associated with higher fasting insulin (4.2% 95% CI 0.9%, 7.4%,), HbA1c (0.4% 95% CI 0.1%, 0.8%), fasting glucose (0.6% 95% CI 0.2%, 1.1%,), urate (5.2% 95% CI 3.9%, 6.6%,) and triglyceride (3.1 95% CI 0.9%, 5.2%) per 1 kg lower birth weight but was not associated with HDL-cholesterol or C-reactive protein. Associations were little affected by adjustment for gestational age. Birth weight was lower among children of South Asian and (to a lesser extent) black African-Caribbean origin by 231g (95% CI 183g, 280g) and 81g (95% CI 30g, 132g) respectively. However, adjustment for birth weight had little or no effect on the higher levels of insulin, HbA1c, C-reactive protein and triglyceride among South Asians when compared with white Europeans. Similarly, adjustment for birth weight had little or no effect on the higher levels of insulin and HbA1c among black African-Caribbeans compared with white Europeans.ConclusionBirth weight was inversely associated with risk markers for type 2 diabetes in childhood, but only after adjustment for height. However, lower birth weights in South Asians and black African-Caribbeans did not explain ethnic differences in risk markers for type 2 diabetes in childhood.
Regulation of long bone growth by growth hormone and other endocrine factors is mediated by the local synthesis of IGF-I in the growth plate. Recent evidence suggests that different regions of the ...growth plate exhibit variable growth rates. To investigate whether IGF-I gene expression in the growth plate differs in relation to growth, we examined the distribution of IGF-I mRNA and peptide using in situ hybridization and immunohistochemistry, respectively, in the tibiae of 18-week-old rats (n = 6). Osteoblasts were identified by osteocalcin immunoreactivity, and osteoclasts by tartrate-resistant acid phosphatase (TRAP) histochemistry. The abundance of IGF-I mRNA in growth plate chondrocytes was quantified by counting the autoradiographic signal associated with each cell. IGF-I mRNA was identified in chondrocytes of both the proliferative and hypertrophic zones of the growth plate. Cells in the marginal regions of both zones contained significantly more IGF-I mRNA than those in the central region (p < 0.05). In addition, IGF-I mRNA levels were greater in the periphery of the growth plate on the medial side of the tibia (p < 0.05) in which there was more active growth than the lateral side. IGF-I immunoreactivity was present predominantly in the hypertrophic zone chondrocytes and no regional differences in its distribution were observed. IGF-I mRNA and peptide were also identified in periosteal fibroblasts, notably at sites of muscle attachment to bone, and in osteoblasts at active sites of bone remodelling in the periosteal, endocortical, and endosteal bone envelopes. In the TRAP-positive osteoclasts, IGF-I immunoreactivity, but not IGF-I mRNA, was detected. In addition, both IGF-I mRNA and peptide were identified in the hemopoietic cells of the metaphyseal bone marrow, whereas only IGF-I immunoreactivity was detectable in the diaphysis. We conclude that, in the tibiae of mature rats: (i) IGF-I gene expression in the growth plate is related to its growth and/or synthetic activity; and (ii) the presence of IGF-I in osteoblasts and osteoclasts suggests its involvement in active bone growth and remodeling.
Glucocorticoids suppress the release of tumour necrosis factor-alpha (TNF-alpha) by macrophages in vitro and cause monocytopaenia in vivo. These actions may contribute to anti-inflammatory and ...immunosuppressant effects. We therefore examined relationships between prednisolone concentration, suppression of monocyte TNF-alpha release, monocytopaenia and suppression of total cortisol concentration in healthy volunteers treated with a single dose (1.5 mg kg-1) of the glucocorticoid, prednisolone.
Monocyte numbers, total cortisol concentration and prednisolone concentration were measured in blood samples collected over 48 h after the dose. Plasma from these samples was also tested for its capacity to suppress lipopolysaccharide-induced TNF-alpha release from monocytes in autologous whole blood cultures.
At 4 h after the dose, monocyte numbers in peripheral blood had fallen to a mean of 18% of the pre-dose level whilst plasma total cortisol had fallen to 9% of the pre-dose concentration. Monocyte numbers recovered in concordance with elimination of prednisolone and there was a significant relative monocytosis at 24 h. The recovery of plasma cortisol was delayed in comparison, with cortisol remaining significantly suppressed at 24 h. Plasma samples taken at 2 h after the dose (corresponding to peak plasma prednisolone concentration) suppressed the lipopolysaccharide-stimulated production of TNF-alpha by autologous blood monocytes to 27% of pre-dose control. Plasma collected at intervals over the 48 h from dosing also suppressed monocyte TNF-alpha release in relation to the prednisolone concentration therein. Suppression was largely reversed by the glucocorticoid antagonist, mifepristone. A similar relationship between prednisolone concentration and TNF-alpha suppression was observed when prednisolone was added to blood samples collected from the volunteers when they were drug-free.
Blood concentration of prednisolone achieved after a dose of 1.5 mg kg-1 are sufficient to suppress monocyte TNF-alpha release and cause a biphasic change in peripheral blood monocyte numbers. Suppression of TNF-alpha is principally a direct glucocorticoid effect, rather than a consequence of other prednisolone-induced changes to blood composition.
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