982 resultados para Proportional
Resumo:
Background: We investigated the incidence of chronic kidney disease (CKD) in the United Kingdom heart transplant population, identified risk factors for the development of CKD, and assessed the impact of CKD on subsequent survival.
Methods: Data from the UK Cardiothoracic Transplant Audit and UK Renal Registry were linked for 1732 adult heart transplantations, 1996 to 2007. Factors influencing time to CKD, defined as National Kidney Foundation CKD stage 4 or 5 or preemptive kidney transplantation, were identified using a Cox proportional hazards model. The effects of distinct CKD stages on survival were evaluated using time-dependent covariates.
Results: A total of 3% of patients had CKD at transplantation, 11% at 1-year and more than 15% at 6 years posttransplantation and beyond. Earlier transplantations, shorter ischemia times, female, older, hepatitis C virus positive, and diabetic recipients were at increased risk of developing CKD, along with those with impaired renal function pretransplantation or early posttransplantation. Significant differences between transplantation centers were also observed. The risk of death was significantly higher for patients at CKD stage 4, stage 5 (excluding dialysis), or on dialysis, compared with equivalent patients surviving to the same time point with CKD stage 3 or lower (hazard ratios of 1.66, 8.54, and 4.07, respectively).
Conclusions: CKD is a common complication of heart transplantation in the UK, and several risk factors identified in other studies are also relevant in this population. By linking national heart transplantation and renal data, we have determined the impact of CKD stage and dialysis treatment on subsequent survival in heart transplant recipients.
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This brief investigates a possible application of the inverse Preisach model in combination with the feedforward and feedback control strategies to control shape memory alloy actuators. In the feedforward control design, a fuzzy-based inverse Preisach model is used to compensate for the hysteresis nonlinearity effect. An extrema input history and a fuzzy inference is utilized to replace the inverse classical Preisach model. This work allows for a reduction in the number of experimental parameters and computation time for the inversion of the classical Preisach model. A proportional-integral-derivative (PID) controller is used as a feedback controller to regulate the error between the desired output and the system output. To demonstrate the effectiveness of the proposed controller, real-time control experiment results are presented.
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Burkholderia cenocepacia is an opportunistic pathogen that displays a remarkably high resistance to antimicrobial peptides. We hypothesize that high resistance to antimicrobial peptides in these bacteria is because of the barrier properties of the outer membrane. Here we report the identification of genes for the biosynthesis of the core oligosaccharide (OS) moiety of the B. cenocepacia lipopolysaccharide. We constructed a panel of isogenic mutants with truncated core OS that facilitated functional gene assignments and the elucidation of the core OS structure in the prototypic strain K56-2. The core OS structure consists of three heptoses in the inner core region, 3-deoxy-d-manno-octulosonic acid, d-glycero-d-talo-octulosonic acid, and 4-amino-4-deoxy-l-arabinose linked to d-glycero-d-talo-octulosonic acid. Also, glucose is linked to heptose I, whereas heptose II carries a second glucose and a terminal heptose, which is the site of attachment of the O antigen. We established that the level of core truncation in the mutants was proportional to their increased in vitro sensitivity to polymyxin B (PmB). Binding assays using fluorescent 5-dimethylaminonaphthalene-1-sulfonyl-labeled PmB demonstrated a correlation between sensitivity and increased binding of PmB to intact cells. Also, the mutant producing a heptoseless core OS did not survive in macrophages as compared with the parental K56-2 strain. Together, our results demonstrate that a complete core OS is required for full PmB resistance in B. cenocepacia and that resistance is due, at least in part, to the ability of B. cenocepacia to prevent binding of the peptide to the bacterial cell envelope.
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The geometry of tree branches can have considerable effect on their efficiency in terms of carbon export per unit carbon investment in structure. The purpose of this study was to evaluate different design criteria using data describing the form of Picea sitchensis branches. Allometric analysis of the data suggests that resources are distributed to favour shoots with the greatest opportunity for extension into new space, with priority to the extension of the leader. The distribution of allometric relations of links (branch elements) was tested against two models: the pipe model, based on hydraulic transport requirements, and a static load model based on the requirement of shoots to provide mechanical resistance to static loads. Static load resistance required the load parameter to be proportional to the link radius raised to the power of 4. This was shown to be true within a 95% statistical confidence limit. The pipe model would require total distal length to be proportional to link radius squared but the measured branches did not conform well to this model. The comparison suggests that the diameters of branch elements were more related to the requirements for mechanical load. The cost of following a hydraulic design principle (the pipe model) in terms of mechanical efficiency was estimated and suggested that the pipe model branch would not be mechanically compromised but would use structural resources inefficiently. Resource allocation among branch elements was found to be consistent with mechanical stability criteria but also indicated the possibility of allocation based on other criteria, such as potential light interception by shoots. The evidence suggests that whilst branch topology increments by reiteration of units of morphogenesis, the geometry follows a functional design pattern.
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Objective To investigate the association between periodontitis and mortality from all causes in a prospective study in a homogenous group of 60- to 70-year-old West European men. Methodology A representative sample of 1400 dentate men, (mean age 63.8, SD 3.0 years), drawn from the population of Northern Ireland, had a comprehensive periodontal examination between 2001 and 2003. Men were divided into thirds on the basis of their mean periodontal attachment loss (PAL). The primary endpoint, death from any cause, was analysed using Kaplan-Meier survival plots and Cox's proportional hazards model. Results In total, 152 (10.9%) of the men died during a mean follow-up of 8.9 (SD 0.7) years; 37 (7.9%) men in the third with the lowest PAL (<1.8 mm) died compared with 73 (15.7%) in the third with the highest PAL (>2.6 mm). The unadjusted hazard ratio (HR) for death in the men with the highest level of PAL compared with those with the lowest PAL was 2.11 (95% CI 1.42-3.14), p < 0.0001. After adjustment for confounding variables (age, smoking, hypertension, BMI, diabetes, cholesterol, education, marital status and previous history of a cardiovascular event) the HR was 1.57 (1.04-2.36), p = 0.03. Conclusion The European men in this prospective cohort study with the most severe loss of periodontal attachment were at an increased risk of death compared with those with the lowest loss of periodontal attachment.
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Aims: To characterize the population pharmacokinetics of ranitidine in critically ill children and to determine the influence of various clinical and demographic factors on its disposition. Methods: Data were collected prospectively from 78 paediatric patients (n = 248 plasma samples) who received oral or intravenous ranitidine for prophylaxis against stress ulcers, gastrointestinal bleeding or the treatment of gastro-oesophageal reflux. Plasma samples were analysed using high-performance liquid chromatography, and the data were subjected to population pharmacokinetic analysis using nonlinear mixed-effects modelling. Results: A one-compartment model best described the plasma concentration profile, with an exponential structure for interindividual errors and a proportional structure for intra-individual error. After backward stepwise elimination, the final model showed a significant decrease in objective function value (-12.618; P <0.001) compared with the weight-corrected base model. Final parameter estimates for the population were 32.1lh for total clearance and 285l for volume of distribution, both allometrically modelled for a 70kg adult. Final estimates for absorption rate constant and bioavailability were 1.31h and 27.5%, respectively. No significant relationship was found between age and weight-corrected ranitidine pharmacokinetic parameters in the final model, with the covariate for cardiac failure or surgery being shown to reduce clearance significantly by a factor of 0.46. Conclusions: Currently, ranitidine dose recommendations are based on children's weights. However, our findings suggest that a dosing scheme that takes into consideration both weight and cardiac failure/surgery would be more appropriate in order to avoid administration of higher or more frequent doses than necessary.
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Abstract: Background: A20 and TAX1BP1 interact to negatively regulate NF-
-driven inflammation. A20 expression is altered in F508del/F508del
patients. Here we explore the effect of CFTR and CFTR genotype on A20 and
TAX1BP1expression. The relationship with lung function is also assessed.
Methods: Primary Nasal Epithelial cells (NECs) from CF patients
(F508del/F508del, n=8, R117H/F508del, n=6) and Controls (age-matched,
n=8), and 16HBE14o- cells were investigated. A20 and TAX1BP1 gene
expression was determined by qPCR.
Results: Silencing of CFTR reduced basal A20 expression. Following LPS
stimulation A20 and TAX1BP1 expression was induced in control NECs and
reduced in CF NECs, broadly reflecting the CF genotype: F508del/F508del
had lower expression than R117H/F508del. A20, but not TAX1BP1 expression,
was proportional to FEV1 in all CF patients (r=0.968, p<0.001).
Conclusions: A20 expression is reduced in CF and is proportional to FEV1.
Pending confirmation in a larger study, A20 may prove a novel predictor
of CF inflammation/disease severity.
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Measurements were made (using fast confocal microscopy) of intracellular Ca2+ levels in fluo-4 loaded interstitial cells isolated from the rabbit urethra. These cells exhibited regular Ca2+ oscillations which were associated with spontaneous transient inward currents recorded under voltage clamp. Interference with D-myo-inositol 1,4,5-trisphosphate (IP3) induced Ca2+ release using 100 microm 2-aminoethoxydiphenyl borate, and the phospholipase C (PLC) inhibitors 2-nitro-4-carboxyphenyl N,N-diphenylcarbamate and U73122 decreased the amplitude of spontaneous oscillations but did not abolish them. However, oscillations were abolished when ryanodine receptors were blocked with tetracaine or ryanodine. Oscillations ceased in the absence of external Ca2+, and frequency was directly proportional to the external Ca2+ concentration. Frequency of Ca2+ oscillation was reduced by SKF-96365, but not by nifedipine. Lanthanum and cadmium completely blocked oscillations. These results suggest that Ca2+ oscillations in isolated rabbit urethral interstitial cells are initiated by Ca2+ release from ryanodine-sensitive intracellular stores, that oscillation frequency is very sensitive to the external Ca2+ concentration and that conversion of the primary oscillation to a propagated Ca2+ wave depends upon IP3-induced Ca2+ release.
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Extreme ultraviolet (XUV) and X-ray harmonic spectra produced by intense laser-solid interactions have, so far, been consistent with Doppler upshifted reflection from collective relativistic plasma oscillations-the relativistically oscillating mirror mechanism(1-6). Recent theoretical work, however, has identified a new interaction regime in which dense electron nanobunches are formed at the plasma-vacuum boundary resulting in coherent XUV radiation by coherent synchrotron emission(7,8) (CSE). Our experiments enable the isolation of CSE from competing processes, demonstrating that electron nanobunch formation does indeed occur. We observe spectra with the characteristic spectral signature of CSE-a slow decay of intensity, I, with high-harmonic order, n, as I(n) proportional to n(-1.62) before a rapid efficiency rollover. Particle-in-cell code simulations reveal how dense nanobunches of electrons are periodically formed and accelerated during normal-incidence interactions with ultrathin foils and result in CSE in the transmitted direction. This observation of CSE presents a route to high-energy XUV pulses(7,8) and offers a new window on understanding ultrafast energy coupling during intense laser-solid density interactions.
Resumo:
Increases in food production and the ever-present threat of food contamination from microbiological and chemical sources have led the food industry and regulators to pursue rapid, inexpensive methods of analysis to safeguard the health and safety of the consumer. Although sophisticated techniques such as chromatography and spectrometry provide more accurate and conclusive results, screening tests allow a much higher throughput of samples at a lower cost and with less operator training, so larger numbers of samples can be analysed. Biosensors combine a biological recognition element (enzyme, antibody, receptor) with a transducer to produce a measurable signal proportional to the extent of interaction between the recognition element and the analyte. The different uses of the biosensing instrumentation available today are extremely varied, with food analysis as an emerging and growing application. The advantages offered by biosensors over other screening methods such as radioimmunoassay, enzyme-linked immunosorbent assay, fluorescence immunoassay and luminescence immunoassay, with respect to food analysis, include automation, improved reproducibility, speed of analysis and real-time analysis. This article will provide a brief footing in history before reviewing the latest developments in biosensor applications for analysis of food contaminants (January 2007 to December 2010), focusing on the detection of pathogens, toxins, pesticides and veterinary drug residues by biosensors, with emphasis on articles showing data in food matrices. The main areas of development common to these groups of contaminants include multiplexing, the ability to simultaneously analyse a sample for more than one contaminant and portability. Biosensors currently have an important role in food safety; further advances in the technology, reagents and sample handling will surely reinforce this position.
Resumo:
We introduce a family of Hamiltonian systems for measurement-based quantum computation with continuous variables. The Hamiltonians (i) are quadratic, and therefore two body, (ii) are of short range, (iii) are frustration-free, and (iv) possess a constant energy gap proportional to the squared inverse of the squeezing. Their ground states are the celebrated Gaussian graph states, which are universal resources for quantum computation in the limit of infinite squeezing. These Hamiltonians constitute the basic ingredient for the adiabatic preparation of graph states and thus open new venues for the physical realization of continuous-variable quantum computing beyond the standard optical approaches. We characterize the correlations in these systems at thermal equilibrium. In particular, we prove that the correlations across any multipartition are contained exactly in its boundary, automatically yielding a correlation area law. © 2011 American Physical Society.
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Architects typically interpret Heidegger to mean that dwelling in the Black Forest, was more authentic than living in an industrialised society however we cannot turn back the clock so we are confronted with the reality of modernisation. Since the Second World War production has shifted from material to immaterial assets. Increasingly place is believed to offer resistance to this fluidity, but this belief can conversely be viewed as expressing a sublimated anxiety about our role in the world – the need to create buildings that are self-consciously contextual suggests that we may no longer be rooted in material places, but in immaterial relations.
This issue has been pondered by David Harvey in his paper From Place to Space and Back Again where he argues that the role of place in legitimising identity is ultimately a political process, as the interpretation of its meaning is dependent on whose interpretation it is. Doreen Massey has found that different classes of people are more or less mobile and that mobility is related to class and education rather than to nationality or geography. These thinkers point to a different set of questions than the usual space/place divide – how can we begin to address the economic mediation of spatial production to develop an ethical production of place? Part of the answer is provided by the French architectural practice Lacaton Vassal in their book Plus. They ask themselves how to produce more space for the same cost so that people can enjoy a better quality of life. Another French practitioner, Patrick Bouchain, has argued that architect’s fees should be inversely proportional to the amount of material resources that they consume. These approaches use economics as a starting point for generating architectural form and point to more ethical possibilities for architectural practice
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Quantitative detection of specific viral DNA has become a pressing issue for the earlier clinical diagnosis of viral infectious diseases. Therefore, in this paper, we report a simple, sensitive, and inexpensive quantitative approach for DNA detection based on the autocatalytic Au deposition of gold nanoprobes via the surface reduction of AuCl4- to Au0 on their surface in the presence of ascorbic acid (AA) and cetyltrimethylammonium bromide (CTAB). On this basis, signal enhancements in the absorbance intensity and kinetic behavior of gold enlargement in the aqueous phase have been well investigated and explained for the selection of analytical parameters. To achieve high sensitivity, magnetic particles conjugated with capture probes (PMPs) were employed for the collection of gold nanoprobes. After denaturated by ion a pH 11 solution, the amplified signals of gold nanoprobes, which is proportional to the concentration of the target DNA, could easily be confirmed by a UV-vis scanning spectrophotometer. Limit of detection could be obtained as low as 1.0 fM by this simple method.
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A downstream target of the Wnt pathway, neurone glial-related cell adhesion molecule (Nr-CAM) has recently been implicated in human cancer development. However, its role in colorectal cancer (CRC) pathobiology and clinical relevance remains unknown. In this study, we examined the clinical significance of Nr-CAM protein expression in a retrospective series of 428 CRCs using immunohistochemistry and tissue microarrays. Cox proportional hazards regression was used to calculate hazard ratios (HR) of mortality according to various clinicopathological features and molecular markers. All CRC samples were immunoreactive for Nr-CAM protein expression, compared to 10 / 245 (4%) matched normal tissue (P <0.0001). Of 428 CRC samples, 97 (23%) showed Nr-CAM overexpression, which was significantly associated with nodal (P = 0.012) and distant (P = 0.039) metastasis, but not with extent of local invasion or tumor size. Additionally, Nr-CAM overexpression was associated with vascular invasion (P = 0.0029), p53 expression (P = 0.036), and peritoneal metastasis at diagnosis (P = 0.013). In a multivariate model adjusted for other clinicopathological predictors of survival, Nr-CAM overexpression correlated with a significant increase in disease-specific (HR 1.66; 95% confidence interval 1.11-2.47; P = 0.014) and overall mortality (HR 1.57; 95% confidence interval 1.07-2.30; P = 0.023) in advanced but not early stage disease. Notably, 5-fluorouracil-based chemotherapy conferred significant survival benefit to patients with tumors negative for Nr-CAM overexpression but not to those with Nr-CAM overexpressed tumors. In conclusion, Nr-CAM protein expression is upregulated in CRC tissues. Nr-CAM overexpression is an independent marker of poor prognosis among advanced CRC patients, and is a possible predictive marker for non-beneficence to 5-fluorouracil- based chemotherapy.
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To determine whether immunocomplexes (ICs) containing advanced glycation end product (AGE)-LDL (AGE-LDL) and oxidized LDL (oxLDL) contribute to the development of retinopathy over a 16-year period in subjects with type 1 diabetes.