987 resultados para 894.541
Resumo:
A system is something that can be separated from its surrounds, but this definition leaves much scope for refinement. Starting with the notion of measurement, we explore increasingly contextual system behaviour, and identify three major forms of contextuality that might be exhibited by a system: (a) between components; (b) between system and experimental method, and; (c) between a system and its environment. Quantum Theory is shown to provide a highly useful formalism from which all three forms of contextuality can be analysed, offering numerous tests for contextual behaviour, as well as modelling possibilities for systems that do indeed display it. I conclude with the introduction of a Contextualised General Systems Theory based upon an extension of this formalism.
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Soluble endoglin is an anti-angiogenic protein that is released from the placenta and contributes to both maternal endothelial dysfunction and the clinical features of severe preeclampsia. The mechanism through which soluble endoglin is released from the placenta is currently unknown; however, recent work in colorectal cancer identified matrix metalloproteinase 14 (MMP-14) as the cleavage protease of endoglin. To determine whether this is also the mechanism responsible for soluble endoglin release in preeclampsia, we investigated the expression of MMP-14 within the placenta and the effects of its inhibition on soluble endoglin release. Placentas were obtained from severe, early onset preeclamptic pregnancies (n = 8) and gestationally matched preterm controls (n = 8). MMP-14 was predominately localized to the syncytiotrophoblast. Results from a proximity ligation assay showed protein interactions between endogenous MMP-14 and endoglin within the preeclamptic placenta. To demonstrate that this interaction produces soluble endoglin, we treated trophoblastic BeWo cells with either a broad-spectrum MMP inhibitor (GM6001) or MMP-14 siRNA. Both treatments produced a decrease in soluble endoglin (P ≤ 0.05). Treatment of mice bearing BeWo xenografts with GM6001 decreased circulating soluble endoglin levels in mouse serum (P ≤ 0.05). These findings indicate that MMP-14 is the likely cleavage protease of endoglin in the setting of preeclampsia. This approach provides a novel method for the development of potential therapeutics to reduce circulating soluble endoglin and ameliorate the clinical features of severe preeclampsia.
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Deficiencies in iodine levels have been shown to seriously affect a child’s intellectual development and learning capacity.1 In South-East Asia, iodine deficiency remains a major public health concern. Approximately 30% of the region’s population of 503.6 million have insufficient iodine intake, and only 61% of households have access to iodized salt.1 For this reason, it is necessary to initiate effective, community-based health promotion activities that are targeted toward populations of various ages. A puppet show is one imaginative and entertaining method of health education that has been advocated for use in communicating positive health behaviours to children.2e5 The authors undertook a literature review and found no studies assessing the effectiveness of a puppet show to teach an iodine education programme...
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Human saliva mirrors body’s health and well-being and many of the biomolecules present in blood or urine can also be found in salivary secretions. However, biomolecular concentrations in saliva are usually one tenth to one thousandth of the levels in blood (Pfaffe et al., 2011). Sensitive detection technology platforms are therefore required to detect biomolecules in saliva. Another road block to the advancement of salivary diagnostics is the lack of information related to healthy state saliva vs. a diseased saliva, baseline levels and reference ranges and diurnal variations. Saliva has numerous advantages over blood or urine as a diagnostic fluid: (a) the non-invasive nature of sample collection and the simple, safe, painless and cost-effective methods to collect it; (b) unskilled personnel can collect saliva samples at multiple time points; and (c) the total protein concentration is approximately a quarter of that is present in plasma, which makes it easier to investigate low abundance proteins (Pfaffe et al., 2011). Currently, saliva assays are routinely used to determine, diseases such as HIV, drugs and substances of abuse to provide information on exposure and give qualitative information on the type of illicit drug used (Kintz et al., 2009), cortisol levels for diagnosing Cushing’s syndrome (Doi et al., 2008), and use for biomonitoring of exposure to chemicals (Caporossi et al., 2010) to measure hormones (Gröschl, 2009)....
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The implicit structure of positive character traits was examined in two studies of 190 and 100 undergraduates. Participants judged the pairwise covariation or semantic similarity of 42 positive characteristics using a sorting or a rating task. Characteristics were drawn from a new classification of strengths and virtues, the Five-Factor Model, and a taxonomy of values. Participants showed consistent patterns of perceived association among the characteristics across the study conditions. Multidimensional scaling yielded three consistent dimensions underlying these judgments (“warmth vs. self-control,” “vivacity vs. decency,” and “wisdom vs. power”). Cluster analyses yielded six consistent groupings—“self-control,” “love,” “wisdom,” “drive,” “vivacity,” and “collaboration”—that corresponded only moderately to the virtue classification. All three taxonomies were systematically related to this implicit structure, but none captured it satisfactorily on its own. Revisions to positive psychology’s classification of strengths are proposed.
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The products evolved during the thermal decomposition of the coal-derived pyrite/marcasite were studied using simultaneous thermogravimetry coupled with Fourier-transform infrared spectroscopy and mass spectrometry (TG-FTIR–MS) technique. The main gases and volatile products released during the thermal decomposition of the coal-derived pyrite/marcasite are water (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2). The results showed that the evolved products obtained were mainly divided into two processes: (1) the main evolved product H2O is mainly released at below 300 °C; (2) under the temperature of 450–650 °C, the main evolved products are SO2 and small amount of CO2. It is worth mentioning that SO3 was not observed as a product as no peak was observed in the m/z = 80 curve. The chemical substance SO2 is present as the main gaseous product in the thermal decomposition for the sample. The coal-derived pyrite/marcasite is different from mineral pyrite in thermal decomposition temperature. The mass spectrometric analysis results are in good agreement with the infrared spectroscopic analysis of the evolved gases. These results give the evidence on the thermal decomposition products and make all explanations have the sufficient evidence. Therefore, TG–MS–IR is a powerful tool for the investigation of gas evolution from the thermal decomposition of materials.
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Background and purpose There are no published studies on the parameterisation and reliability of the single-leg stance (SLS) test with inertial sensors in stroke patients. Purpose: to analyse the reliability (intra-observer/inter-observer) and sensitivity of inertial sensors used for the SLS test in stroke patients. Secondary objective: to compare the records of the two inertial sensors (trunk and lumbar) to detect any significant differences in the kinematic data obtained in the SLS test. Methods Design: cross-sectional study. While performing the SLS test, two inertial sensors were placed at lumbar (L5-S1) and trunk regions (T7–T8). Setting: Laboratory of Biomechanics (Health Science Faculty - University of Málaga). Participants: Four chronic stroke survivors (over 65 yrs old). Measurement: displacement and velocity, Rotation (X-axis), Flexion/Extension (Y-axis), Inclination (Z-axis); Resultant displacement and velocity (V): RV=(Vx2+Vy2+Vz2)−−−−−−−−−−−−−−−−−√ Along with SLS kinematic variables, descriptive analyses, differences between sensors locations and intra-observer and inter-observer reliability were also calculated. Results Differences between the sensors were significant only for left inclination velocity (p = 0.036) and extension displacement in the non-affected leg with eyes open (p = 0.038). Intra-observer reliability of the trunk sensor ranged from 0.889-0.921 for the displacement and 0.849-0.892 for velocity. Intra-observer reliability of the lumbar sensor was between 0.896-0.949 for the displacement and 0.873-0.894 for velocity. Inter-observer reliability of the trunk sensor was between 0.878-0.917 for the displacement and 0.847-0.884 for velocity. Inter-observer reliability of the lumbar sensor ranged from 0.870-0.940 for the displacement and 0.863-0.884 for velocity. Conclusion There were no significant differences between the kinematic records made by an inertial sensor during the development of the SLS testing between two inertial sensors placed in the lumbar and thoracic regions. In addition, inertial sensors. Have the potential to be reliable, valid and sensitive instruments for kinematic measurements during SLS testing but further research is needed.
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Many physical processes appear to exhibit fractional order behavior that may vary with time and/or space. The continuum of order in the fractional calculus allows the order of the fractional operator to be considered as a variable. In this paper, we consider a new space–time variable fractional order advection–dispersion equation on a finite domain. The equation is obtained from the standard advection–dispersion equation by replacing the first-order time derivative by Coimbra’s variable fractional derivative of order α(x)∈(0,1]α(x)∈(0,1], and the first-order and second-order space derivatives by the Riemann–Liouville derivatives of order γ(x,t)∈(0,1]γ(x,t)∈(0,1] and β(x,t)∈(1,2]β(x,t)∈(1,2], respectively. We propose an implicit Euler approximation for the equation and investigate the stability and convergence of the approximation. Finally, numerical examples are provided to show that the implicit Euler approximation is computationally efficient.
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In this paper, we present a machine learning approach to measure the visual quality of JPEG-coded images. The features for predicting the perceived image quality are extracted by considering key human visual sensitivity (HVS) factors such as edge amplitude, edge length, background activity and background luminance. Image quality assessment involves estimating the functional relationship between HVS features and subjective test scores. The quality of the compressed images are obtained without referring to their original images ('No Reference' metric). Here, the problem of quality estimation is transformed to a classification problem and solved using extreme learning machine (ELM) algorithm. In ELM, the input weights and the bias values are randomly chosen and the output weights are analytically calculated. The generalization performance of the ELM algorithm for classification problems with imbalance in the number of samples per quality class depends critically on the input weights and the bias values. Hence, we propose two schemes, namely the k-fold selection scheme (KS-ELM) and the real-coded genetic algorithm (RCGA-ELM) to select the input weights and the bias values such that the generalization performance of the classifier is a maximum. Results indicate that the proposed schemes significantly improve the performance of ELM classifier under imbalance condition for image quality assessment. The experimental results prove that the estimated visual quality of the proposed RCGA-ELM emulates the mean opinion score very well. The experimental results are compared with the existing JPEG no-reference image quality metric and full-reference structural similarity image quality metric.
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Road deposited dust is a complex mixture of pollutants derived from a wide range of sources. Accurate identification of these sources is seminal for effective source-oriented control measures. A range of techniques such as enrichment factor analysis (EF), principal component analysis (PCA) and hierarchical cluster analysis (HCA) are available for identifying sources of complex mixtures. However, they have multiple deficiencies when applied individually. This study presents an approach for the effective utilisation of EF, PCA and HCA for source identification, so that their specific deficiencies on an individual basis are eliminated. EF analysis confirmed the non-soil origin of metals such as Na, Cu, Cd, Zn, Sn, K, Ca, Sb, Ba, Ti, Ni and Mo providing guidance in the identification of anthropogenic sources. PCA and HCA identified four sources, with soil and asphalt wear in combination being the most prominent sources. Other sources were tyre wear, brake wear and sea salt.
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Stress analysis within carotid plaques based on in vivo MR imaging has shown to be useful for the identification of vulnerable atheroma. This study is to investigate whether magnetic resonance imaging (MRI) based-biomechanical stress analysis of carotid plaques can differentiate acute symptomatic and asymptomatic patients. 54 asymptomatic and 45 acute symptomatic patients underwent in vivo multi-contrast MRI of the carotid arteries. Plaque geometry used for finite element analysis was derived from in vivo MR images at the site of maximum and minimum plaque burden. In total 198 slices were used for the computational simulations. A pre shrink technique was used to refine the simulation. Maximum principle stress at the vulnerable plaque sites (i.e. critical stress) was extracted for the selected slices and a comparison was performed between the two groups. Critical stress at the site of maximum plaque burden is significantly higher in acute symptomatic patients as compared to asymptomatic patients [median: 198.0kPa (inter quartile range (IQR) = (119.8 - 359.0) vs. 138.4kPa (83.8, 242.6), p=0.04]. No significant difference was found at the minimum plaque burden site between the two groups [196.7kPa (133.3- 282.7) vs. 182.4kPa (117.2 - 310. 6), p=0.82). Stress analysis at the site of maximal plaque burden can be effectively used for differentiating acute symptomatic carotid plaques from asymptomatic plaques. This maybe potentially used for development of biomechanical risk stratification criteria based on plaque burden in future studies.
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Yellow form (I): Mr= 350.09, monoclinic, P2Jn, Z--4, a=9.525(1), b=14.762(1), c= 11.268(1),/t, fl= 107.82 (1) o , V= 1508.3 A 3 , Din(flotation in aqueous KI)= 1.539 (2), D x= 1.541 (2) g cm -3, #(Cu Ka, 2 = 1.5418 A) = 40.58 cm -~, F(000) = 712, T= 293 K, R = 8.8% for 2054 significant refections. Red form (II): Mr= 350.09, triclinic, Pi, Z=2, a=9.796(2), b= 10.750 (2), c= 7.421 (1)A, a= 95.29 (2), fl= 0108-2701/84/111901-05501.50 70.18 (1), y = 92-.76 (2) °, V= 731.9 A 3, Din(flotation in KI) = 1.585 (3), D x = 1.588 (3) g cm -3, ~t(Cu Ka, 2 = 1.5418/~) = 40.58 cm -1, F(000) = 356, T=293 K, R = 5.8% for 1866 significant reflections. There are no unusual bond distances or angles. The triazole and two phenyl rings are planar. On the basis of packing considerations the possibility of intermolecular interactions playing a role in the reactivity of the starting material is ruled out.
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In view of its non-toxicity, and good dielectric properties, castor oil, a polar liquid dielectric of vegetable origin is suggested as a possible alternative to PCB's for capacitor applications. In this paper the dielectric properties (including partial discharge behavior), of all-polypropylene and paper-polypropylene capacitors with castor oil as impregnant, are reported. The paper also contains results of life studies conducted under accelerated electrical and thermal stresses when they are occurring both individually and combined. The data obtained have been statistically analyzed and approximate life of the system calculated bylinear extrapolation.
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This paper describes a new analysis of the avalanche breakdown phenomenon in bipolar transistors for different bias conditions of the emitter-base junction. This analysis revolves around the transportation and storage of majority carriers in the base region. Using this analysis one can compute all the voltage-current characteristics of a transistor under avalanche breakdown.