74 resultados para 3-BODY FORCE


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The term `laser cooling' is applied to the use of optical means to cool the motional energies of either atoms and molecules, or micromirrors. In the literature, these two strands are kept largely separate; both, however suffer from severe limitations. Laser cooling of atoms and molecules largely relies on the internal level structure of the species being cooled. As a result, only a small number of elements and a tiny number of molecules can be cooled this way. In the case of micromirrors, the problem lies in the engineering of micromirrors that need to satisfy a large number of constraints---these include a high mechanical Q-factor, high reflectivity and very good optical quality, weak coupling to the substrate, etc.---in order to enable efficient cooling. During the course of this thesis, I will draw these two sides of laser cooling closer together by means of a single, generically applicable scattering theory that can be used to explain the interaction between light and matter at a very general level. I use this `transfer matrix' formalism to explore the use of the retarded dipole--dipole interaction as a means of both enhancing the efficiency of micromirror cooling systems and rendering the laser cooling of atoms and molecules less species selective. In particular, I identify the `external cavity cooling' mechanism, whereby the use of an optical memory in the form of a resonant element (such as a cavity), outside which the object to be cooled sits, can potentially lead to the construction of fully integrated optomechanical systems and even two-dimensional arrays of translationally cold atoms, molecules or even micromirrors.

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Background: One-carbon metabolism involves both mitochondrial and cytosolic forms of folate-dependent enzymes in mammalian cells, but few in vivo data exist to characterize the biochemical processes involved.

Objective: We conducted a stable-isotopic investigation to determine the fates of exogenous serine and serine-derived one carbon units in homocysteine remethylation in hepatic and whole-body metabolism.

Design: A healthy man aged 23 y was administered [2,3,3 H-2(3)]serine and [5,5,5-H-2(3)]leucine by intravenous primed, constant infusion. Serial plasma samples were analyzed to determine the isotopic enrichment of free glycine, serine, leucine, methionine, and cystathionine. VLDL apolipoprotein B-100 served as an index of liver free amino acid labeling.

Results: [H-2(1)]Methionine and [H-2(2)]methionine were labeled through homocysteine remethylation. We propose that [H-2(2)]methionine occurs by remethylation with [H-2(2)]methyl groups (as 5-methyltetrahydrofolate) formed only from cytosolic processing of [H-2(3)]serine, whereas [H-2(1)]methionine is formed with labeled one-carbon units from mitochondrial oxidation of C-3 serine to [H-2(1)]formate to yield cytosolic [H-2(1)]methyl groups. The labeling pattern of cystathionine formed from homocysteine and labeled serine suggests that cystathionine is derived mainly from a serine pool different from that used in apolipoprotein B-100 synthesis.

Conclusions: The appearance of both [H-2(1)]- and [H-2(2)]methionine forms indicates that both cytosolic and mitochondrial metabolism of exogenous serine generates carbon units in vivo for methyl group production and homocysteine remethylation. This study also showed the utility of serine infusion and indicated functional roles of cytosolic and mitochondrial compartments in one-carbon metabolism.

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Human acute-phase serum amyloid A protein (A-SAA) is a major acute phase reactant, the concentration of which increases dramatically as part of the body's early response to inflammation. A-SAA is the product of two almost identical genes, SAA1 and SAA2, which are induced by the pro-inflammatory cytokines, IL-1 and IL-6. In this study, we examine the roles played by the 5'- and 3'-untranslated regions (UTRs) of the SAA2 mRNA in regulating A-SAA2 expression. SAA2 promoter-driven luciferase reporter gene constructs carrying the SAA2 5'-UTR and/or 3'-UTR were transiently transfected into the HepG2 human hepatoma cell line. After induction of chimeric mRNA with IL-1beta and IL-6, the SAA2 5'- and 3'-UTRs were both able to posttranscriptionally modify the expression of the luciferase reporter. The SAA2 5'-UTR promotes efficient translation of the chimeric luciferase transcripts, whereas the SAA2 3'-UTR shares this property and also significantly accelerates the rate of reporter mRNA degradation. Our data strongly suggest that the SAA2 5'- and 3'-UTRs each play significant independent roles in the posttranscriptional regulation of A-SAA2 protein synthesis.

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Arsenic is accumulated by free-living small mammals, but there is little information on the resultant concentrations in different tissues other than liver and kidney. Such information is important because the severity of toxicological effects may be related to the amount of arsenic accumulated in specific organs, and the availability of arsenic to predators is, in part, dependent on which tissues accumulate arsenic. The objective of this study was to quantify the arsenic concentrations and the percentage of the total body burden (%TBB) accumulated in different body tissues of free-living small mammals and to determine how these factors varied with severity of habitat contamination. Arsenic concentrations were measured in various tissues of wood mice (Apodemus sylvaticus) and bank voles (Clethrionomys glareolus) from a range of arsenic-contaminated sites in southwest Britain. Arsenic concentrations in the gastrointestinal (GI) tract (including contents), liver, kidneys, spleen, lung, femur, and fur of both species varied significantly between sites and were higher in mice and voles from heavily contaminated areas. Heart and brain arsenic concentrations did not vary with degree of environmental contamination. The GI tract and excised carcass contained roughly equal amounts of arsenic and, in sum, comprised 75-85% of the TBB on uncontaminated sites and 90-99% on contaminated sites. Although the excised carcass contains about half of the TBB, its importance in food-chain transfer of arsenic to predators may depend on the bioavailability of arsenic sequestered in fur. In contrast, the GI tract and its contents, provided that it is consumed, will always be a major transfer pathway for arsenic to predators, regardless of the severity of habitat contamination.

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The prediction and management of ecosystem responses to global environmental change would profit from a clearer understanding of the mechanisms determining the structure and dynamics of ecological communities. The analytic theory presented here develops a causally closed picture for the mechanisms controlling community and population size structure, in particular community size spectra, and their dynamic responses to perturbations, with emphasis on marine ecosystems. Important implications are summarised in non-technical form. These include the identification of three different responses of community size spectra to size-specific pressures (of which one is the classical trophic cascade), an explanation for the observed slow recovery of fish communities from exploitation, and clarification of the mechanism controlling predation mortality rates. The theory builds on a community model that describes trophic interactions among size-structured populations and explicitly represents the full life cycles of species. An approximate time-dependent analytic solution of the model is obtained by coarse graining over maturation body sizes to obtain a simple description of the model steady state, linearising near the steady state, and then eliminating intraspecific size structure by means of the quasi-neutral approximation. The result is a convolution equation for trophic interactions among species of different maturation body sizes, which is solved analytically using a novel technique based on a multiscale expansion.

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OBJECTIVES: To determine whether the daily use of 5% tea tree oil (TTO) body wash (Novabac 5% Skin Wash) compared with standard care [Johnson's Baby Softwash (JBS)] had a lower incidence of methicillin-resistant Staphylococcus aureus (MRSA) colonization.

PATIENTS: The study setting was two intensive care units (ICUs; mixed medical, surgical and trauma) in Northern Ireland between October 2007 and July 2009. The study population comprised 391 patients who were randomized to JBS or TTO body wash.

METHODS: This was a Phase 2/3, prospective, open-label, randomized, controlled trial. Trial registration: ISRCTN65190967. The primary outcome was new MRSA colonization during ICU stay. Secondary outcomes included the incidence of MRSA bacteraemia and maximum increase in sequential organ failure assessment score.

RESULTS: A total of 445 patients were randomized to the study. After randomization, 54 patients were withdrawn; 30 because of a positive MRSA screen at study entry, 11 due to lack of consent, 11 were inappropriately randomized and 2 had adverse reactions. Thirty-nine (10%) patients developed new MRSA colonization (JBS n?=?22, 11.2%; TTO body wash n?=?17, 8.7%). The difference in percentage colonized (2.5%, 95% CI -?8.95 to 3.94; P?=?0.50) was not significant. The mean maximum increase in sequential organ failure assessment score was not significant (JBS 1.44, SD 1.92; TTO body wash 1.28, SD 1.79; P?=?0.85) and no study patients developed MRSA bacteraemia.

CONCLUSIONS: Compared with JBS, TTO body wash cannot be recommended as an effective means of reducing MRSA colonization.

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This paper examines the relationship between class of origin, educational attainment, and class of entry to the labour force, in three cohorts of men in the Republic of Ireland using data collected in 1987. The three cohorts comprise men born (i) before 1937; (ii) between 1937 and 1949; and (iii) between 1950 and 1962. The paper assesses the degree of change over the three cohorts in respect of (a) the gross relationship between origins and entry class; (b) the partial effect (controlling for education) of origin class on entry class; (c) the partial effect of education (controlling for origins) on class of entry. In broad terms the liberal theory of industrialism would imply a movement, over the three cohorts, towards (a) increasing social fluidity; (b) a weakening of the partial effect of origin class; (c) a strengthening of the partial effect of education. These latter two trends should be particularly noticeable in the youngest cohort, which would, to some degree, have benefited from the introduction of free post-primary education in Ireland in 1967.

Our results provide almost no support for these hypotheses. We find that patterns of social fluidity in the origin/entry relationship remain unchanged over the cohorts. The partial effect of class remains relatively constant; and, while the partial effect of education on entry class changes over the cohorts, the most striking result in this area is the declining returns to higher levels of education. While the average level of educational attainment increased over the three cohorts, the advantages accruing to the possession of higher levels of education simultaneously diminished. Taken together our results suggest that, in Ireland, those classes that have historically enjoyed advantages in access to more desirable entry positions in the labour market have been remarkably adept at retaining their advantages during the course of industrialization and through the various educational and other labour market changes that have accompanied this process.

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In hypersonic flight, the prediction of aerodynamic heating and the construction of a proper thermal protection system (TPS) are significantly important. In this study, the method of a film cooling technique, which is already the state of the art in cooling of gas turbine engines, is proposed for a fully reusable and active TPS. Effectiveness of the film cooling scheme to reduce convective heating rates for a blunt-nosed spacecraft flying at Mach number 6.56 and 40 deg angle of attack is investigated numerically. The inflow boundary conditions used the standard values at an altitude of 30 km. The computational domain consists of infinite rows of film cooling holes on the bottom of a blunt-nosed slab. Laminar and several turbulent calculations have been performed and compared. The influence of blowing ratios on the film cooling effectiveness is investigated. The results exhibit that the film cooling technique could be an effective method for an active cooling of blunt-nosed bodies in hypersonic flows.

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Objective: To assess the prevalence of overweight and obesity, and the impact of body mass index (BMI) on maternal and neonatal outcomes, in a UK obstetric population.
Design: Retrospective study.
Setting: A tertiary referral unit in Northern Ireland.
Population: A total of 30 298 singleton pregnancies over an 8-year period, 2004–2011.
Methods: Women were categorised according to World Health Organization classification: underweight (BMI < 18.50 kg/m2); normal weight (BMI 18.50–24.99 kg/m2; reference group); overweight (BMI 25.00–29.99 kg/m2); obese class I (BMI 30.00–34.99 kg/m2); obese class II (BMI 35–39.99 kg/m2); and obese class III (BMI = 40 kg/m2). Maternal and neonatal outcomes were examined using logistic regression, adjusted for confounding variables.
Main outcome measures: Maternal and neonatal outcomes.
Results: Compared with women of normal weight, women who were overweight or obese class I were at significantly increased risk of hypertensive disorders of pregnancy (OR 1.9, 99% CI 1.7–2.3; OR 3.5, 99% CI 2.9–4.2); gestational diabetes mellitus (OR 1.7, 99% CI 1.3–2.3; OR 3.7, 99% CI 2.8–5.0); induction of labour (OR 1.2, 99% CI 1.1–1.3; OR 1.3, 99% CI 1.2–1.5); caesarean section (OR 1.4, 99% CI 1.3–1.5; OR 1.8, 99% CI 1.6–2.0); postpartum haemorrhage (OR 1.4, 99% CI 1.3–1.5; OR 1.8, 1.6–2.0); and macrosomia (OR 1.5, 99% CI 1.3–1.6; OR 1.9, 99% CI 1.6–2.2), with the risks increasing for obese classes II and III. Women in obese class III were at increased risk of preterm delivery (OR 1.6, 99% CI 1.1–2.5), stillbirth (OR 3.0, 99% CI 1.0–9.3), postnatal stay > 5 days (OR 2.1, 99% CI 1.5–3.1), and infant requiring admission to a neonatal unit (OR 1.6, 99% CI 1.0–2.6).
Conclusions: By categorising women into overweight and obesity subclassifications (classes I –III), this study clearly demonstrates an increasing risk of adverse outcomes across BMI categories, with women who are overweight also at significant risk.
Keywords Body mass index, maternal and neonatal outcomes,obesity, pregnancy

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We report the magnetic and electrical characteristics of polycrystalline FeTiO3 synthesized at high pressure that is isostructural with acentric LiNbO3 (LBO). Piezoresponse force microscopy, optical second harmonic generation, and magnetometry demonstrate ferroelectricity at and below room temperature and weak ferromagnetism below ~120??K. These results validate symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and weak ferromagnetism in a series of transition metal titanates crystallizing in the LBO structure.

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In this chapter the authors explore a practice-led approach to understanding the role of the body in music performance.

Many writers have discussed the body in music performance, in improvised music, as well as in electronic music. In this chapter the authors offer new modalities of reflection on the musical body in the interpretation of existing contemporary repertoire. Specifically, the authors discuss a re-interpretation of German composer Karlheinz Stockhausen's musical work 'Tierkreis'. Through the development of a specifically physical approach to the performance, the authors investigate the intrinsic relationship between the body and the music and point to an under-explored modality, which is not a musical choreography, but a choreography that is shaped through the musical body itself. It is a modality in which music itself propels forward choreographic ideas, the body becoming the driving force behind musical interpretation. The authors' thinking is influenced by Susan Kozel’s understanding of performance as an ecosystem (Kozel 2007) and framed within a subjective account of musical embodiment.

By merging theory with praxis the authors offer a deeper understanding of the role of the body in music performance and consider how such contributions might lead to new and exciting interpretive frameworks for existing musical repertoires.

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Because of its superior time resolution, ultra-wide bandwidth (UWB) transmission can be a highly accurate technique for ranging in indoor localization systems. Nevertheless, the presence of obstructions may deteriorate the ranging performance of the system. Indoor environments are often densely populated with people. However, t h e effect of the human body presence has been scarcely investigated so far within the UWB ranging context. In this work, we investigate this effect by conducting UWB measurements and analyzing the ranging performance of the system. Two measurement campaigns were performed in the 3-5.5 GHz band, in an anechoic chamber and a laboratory environment. The range estimates were obtained by employing the threshold-based first peak detection technique. Analysis results revealed that the human body significantly attenuates the direct-path signal component. On the other hand, in this study it does not introduce a significant range error since the length difference between the diffracted paths around the body and the direct-path is less than the spatial resolution of the measurement setup. © 2012 IEEE.

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3-Deoxyglucosone (3-DG) is a reactive dicarbonyl sugar thought to be a key intermediate in the nonenzymatic polymerization and browning of proteins by glucose. 3-DG may be formed in vivo from fructose, fructose 3-phosphate, or Amadori adducts to protein, such as N epsilon-fructoselysine (FL), all of which are known to be elevated in body fluids or tissues in diabetes. Modification of proteins by 3-DG formed in vivo is thought to be limited by enzymatic reduction of 3-DG to less reactive species, such as 3-deoxyfructose (3-DF). In this study, we have measured 3-DF, as a metabolic fingerprint of 3-DG, in plasma and urine from a group of diabetic patients and control subjects. Plasma and urinary 3-DF concentrations were significantly increased in the diabetic compared with the control population (0.853 +/- 0.189 vs. 0.494 +/- 0.072 microM, P <0.001, and 69.9 +/- 44.2 vs. 38.7 +/- 16.1 nmol/mg creatinine, P <0.001, respectively). Plasma and urinary 3-DF concentrations correlated strongly with one another, with HbA1c (P <0.005 in all cases), and with urinary FL (P <0.02 and P = 0.005, respectively). The overall increase in 3-DF concentrations in plasma and urine in diabetes and their correlation with other indexes of glycemic control suggest that increased amounts of 3-DG are formed in the body during hyperglycemia in diabetes and then metabolized to 3-DF. These observations are consistent with a role for increased formation of the dicarbonyl sugar 3-DG in the accelerated browning of tissue proteins in diabetes.

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The worldwide epidemic of obesity is a major public health concern and is persuasively linked to the rising prevalence of diabetes and cardiovascular disease. Obesity is often associated with an abnormal lipoprotein profile, which may be partly negated by pioglitazone intervention, as this can influence the composition and oxidation characteristics of low-density lipoprotein (LDL). However, as pioglitazone's impact on these parameters within high-density lipoprotein (HDL), specifically HDL(2&3), is absent from the literature, this study was performed to address this shortcoming.