5,306 research outputs found
STUDY OF A CLOSED-LOOP CONVEYOR SYSTEM
No full textIn this paper, we study a closed-loop conveyor system with equally spaced transportation devices and only one unloading station. We first discuss the dynamic behavior and, in particular, we point out the non-blocking conditions of this system. We consider the steady-state of the conveyor system and give the values of the expected in-process inventory and of the expected production cycle according to the length of the conveyor
Theoretical investigation on radiation tolerance of Mn+1 AX(n) phases
No full textTernary M(n + 1)AX(n) phases with layered hexagonal structures, as candidate materials used for next-generation nuclear reactors, have shown great potential in tolerating radiation damage due to their unique combination of ceramic and metallic properties. However, Mn + 1AXn materials behave differently in amorphization when exposed to energetic neutron and ion irradiations in experiment. We first analyze the irradiation tolerances of different M(n + 1)AX(n) (MAX) phases in terms of electronic structure, including the density of states ( DOS) and charge density map. Then a new method based on the Bader analysis with the first-principle calculation is used to estimate the stabilities of MAX phases under irradiation. Our calculations show that the substitution of Cr/V/Ta/Nb by Ti and Si/Ge/Ga by Al can increase the ionicities of the bonds, thus strengthening the radiation tolerance. It is also shown that there is no obvious difference in radiation tolerance between Mn (+ 1)AC(n) and Mn (+ 1)AN(n) due to the similar charge transfer values of C and N atoms. In addition, the improved radiation tolerance from Ti3AlC2 to Ti2AlC ( Ti3AlC2 and Ti2AlC have the same chemical elements), can be understood in terms of the increased Al/TiC layer ratio. Criteria based on the quantified charge transfer can be further used to explore other M(n + 1)AX(n) phases with respect to their radiation tolerance, playing a critical role in choosing appropriate MAX phases before they are subjected to irradiation in experimental test for future nuclear reactors
The SSC of the Generalised Jahangir’s Graph Jm,k and its Algebraic Characterizations
No full textIn this article, we present important combinatorial and algebraicproperties of spanning simplicial complex (SSC) of the generalised Jahangir’sgraph Jm,k. We describe the relation to find f−vectors associatedto Δs(Jm,k) and determine the Hilbert series for the SR-ring KΔs(Jm,k).In the end, we present the associated primes of the facet ideal IF(Δs(Jm,k))and the Cohen-Macaulay characterization of the SR-ring of Δs(Jm,k).AMS (MOS) Subject Classification Codes: Primary 13-P10, Secondary 13-F20, 13-C14, 13-H10.Corresponding Author: Agha KashifKey Words: Simplicial Complexes, f-vectors, Spanning Trees, Face Ring, Hilbert Series, CohenMacaulay
The etiology of esophageal cancer in high- and low- risk areas of Jiangsu province, China
No full text [Background]Esophageal cancer (EC) remains one of the most common and fatal malignancies worldwide. The geographic variation in EC occurrence is striking, and China is an area with one of the highest incidences of EC. A number of epidemiological studies have been conducted toward EC in the past decades, results suggested that tobacco smoking, alcohol drinking, unhealthy dietary factors and chronic injuries of the esophageal mucosa are important in the development of this disease. Genetic polymorphisms in enzymes involved in metabolism of carcinogens may also influence individual susceptibility. However, the effects of major lifestyle and hereditary risk factors on the development of EC remain poorly understood in China. Moreover, little attention has been paid to the etiological heterogeneity between similar areas with great risk gradient. [Methods]From 2003 to 2007, a large population-based case-control study of EC has been conducted in a selected high-risk area and a selected low-risk area of Jiangsu Province, one of the highest cancer incidence areas in China. In total, 1,520 cases and 3,879 controls were recruited. In this thesis, we evaluated the role of major lifestyle factors such as tobacco smoking, alcohol drinking and dietary factors, as well as inherited determinants including family history of cancer and genetic polymorphisms of alcohol-metabolizing related genes on the risk of EC. In addition, we investigated how much of the risk gradient between two areas could be explained by variation in the distributions of major risk factors. [Results] Tobacco smoking and alcohol drinking moderately increased the risk of EC, while the positive associations were only found among men but not among women. Dietary factors were observed to play important roles in the development of EC. Specific dietary habits i.e., fast eating speed, and hot eating and/or drinking substantially elevated EC risk and could explain more than 20% of EC cases each. High intake of salty foods and fried foods, low consumption of raw garlic were also observed to increase the risk of EC. In addition to environmental and lifestyle factors, we confirmed that a positive family history can significantly increase EC risk, and found the inheritance may modify the effect of some unhealthy lifestyles. Moreover, we further explored the relationship between EC and single nucleotide polymorphismsof ADH1B, ADH1C and ALDH2 genes. Results showed that the slow metabolizing ADH1B G allele, ADH1C G allele and ALDH2 A allele significantly increased EC risk among moderate-to-heavy alcohol drinkers, and a significant interaction was observed between ALDH2 gene and alcohol consumption. Lastly, we found that more than 60% of EC cases could be attributable to major lifestyle risk factors in the study population; furthermore, dissimilar distribution of several lifestyle factors, together with variations of hereditary factors may be largely responsible for the incidence difference between two study areas. [Conclusion]The findings in this thesis confirm that unhealthy lifestyles including smoking, alcohol drinking and some dietary factors are the predominant risk factors of EC in China, and a large proportion of incidence difference between regions at varying risk could be attributed to the different prevalence of lifestyle factors. As most of the identified risk factors are modifiable, these could be translated into risk reduction prevention programs in China, and a substantial proportion of new EC cases are expected to be prevented by eliminating or avoiding these risk factors in the population. </p
To <i>JM</i> on Its 75th Anniversary
No full text This article discusses how Journal of Marketing ( JM) has influenced marketing science and practice by publishing articles on substantive topics relevant to customers, managers, organizations, markets, and society. The journal's 75th anniversary coincides with the 50th anniversary of the Marketing Science Institute (MSI). Frequently, JM and MSI have collaborated to address important substantive marketing issues identified in MSI's Research Priorities. The author highlights seminal articles on brand equity; business-to-business marketing (including sales force management); connecting marketing information, metrics, and strategy; consumer behavior; innovation, new product development. and product management; marketing orientation and capabilities; and market research, methodology and services. She also draws attention to articles that have won the Sheth Foundation/ JM Award and the H. Paul Root Award. The article describes how JM‘s knowledge dissemination is amplified by powerful social network effects. Ideas in JM articles diffuse through the business community, influencing the mind-set of managers worldwide. </jats:p
Ion diffusion coefficient measurements in nanochannels at various concentrations
No full textDiffusion is one of the most fundamental properties of ionic transport in solutions. Here, we present experimental studies and theoretical analysis on the ion diffusion in nanochannels. Based on Fick's second law, we develop a current monitoring method to measure ion diffusion coefficient of high solution concentrations in nanochannels. This method is further extended to the cases at medium and low concentrations. Through monitoring ionic current during diffusion, we obtain diffusion coefficients of potassium chloride solution at different concentrations in nanochannels. These diffusion coefficients within the confined space are close to theirs bulk values. It is also found that the apparent ion diffusion equilibrium in the present experiments is very slow at low concentration, which we attribute to the slow equilibrium of the nanochannel surface charge. Finally, we get a primary acknowledge of the equilibrium rate between the nanochannel surface charge and electrolyte solution. The results in this work have improved the understanding of nanoscale diffusion and nanochannel surface charge and may be useful in nanofluidic applications such as ion-selective transport, energy conversion, and nanopore biosensors. (C) 2014 AIP Publishing LLC
SULFUR-DIOXIDE AND SODIUM METABISULFITE INDUCE BRONCHOCONSTRICTION IN THE ISOLATED-PERFUSED AND VENTILATED GUINEA-PIG LUNG VIA STIMULATION OF CAPSAICIN-SENSITIVE SENSORY NERVES
No full textIn this study the relationship between sulfur dioxide-induced sensory nerve activation and acute bronchoconstriction was assessed. We also studied the effects of sodium metabisulfite, an agent that is suggested to increase airway resistance via activation of sensory nerves. Sulfur dioxide (250 ppm) induced a characteristic biphasic bronchoconstriction. Concomitantly sulfur dioxide induced the release of calcitonin gene-related peptide (CGRP) from capsaicin-sensitive sensory nerves into the pulmonary circulation. In lungs of guinea pi,os pretreated with a neurotoxic dose of capsaicin, the first phase of bronchoconstriction was reduced and the overflow of CGRP was not detectable. Tetrodotoxin abolished the initial phase of the bronchoconstriction induced by sulfur dioxide, indicating that a local neural reflex depending on sodium channels was operant. Inhibition of the vanilloid receptor with capsazepine slightly, although not significantly, reduced the contractile responses to sulfur dioxide. Sodium metabisulfite, when infused via the pulmonary circulation (3 mM), induced bronchoconstriction which was abolished by capsaicin pretreatment, but not significantly reduced by capsazepine. The results indicate that in the isolated guinea pig lung inhaled sulfur dioxide induces initial bronchoconstriction in part via sensory nerve activation, while other mechanisms are involved in the late effect. Sensory nerve activation appears to be the only mechanism for bronchoconstriction induced by infused sodium metabisulfite. A role for sensory nerve-mediated bronchoconstriction by sulfur dioxide or sodium metabisulfite via activation of the vanilloid receptor could not be conclusively demonstrated by this study using capsazepine
Insulin-like growth factor I and interleukin-6 contribute synergistically to disability and mortality in older women
No full textThe physiology of age-related functional decline is poorly understood, but may involve hormones and inflammation. We hypothesized that older women with both low IGF-I and high IL-6 levels are at high risk for disability and death. We assessed walking speed and disability in 718 women enrolled in the Women's Health and Aging Study I, a 3-yr cohort study with 5-yr mortality follow-up. Women with IGF-I levels in the lowest quartile and IL-6 levels in the highest quartile had significantly greater limitation in walking and disability in mobility tasks and instrumental activities of daily living than those with neither risk factor (adjusted odds ratios, 10.77, 5.14, and 3.66). Women with both risk factors were at greater risk for death (adjusted relative risk, 2.10) as well as incident walking limitation, mobility disability, and disability in activities of daily living compared with those with high IGF-I and low IL-6 levels. The combination of low IGF-I and high IL-6 levels confers a high risk for progressive disability and death in older women, suggesting an aggregate effect of dysregulation in endocrine and immune systems. The joint effects of IGF-I and IL-6 may be important targets for treatments to prevent or minimize disability associated with aging
Diabetes, hyperglycaemia and mortality in disabled older women: The Women's Health and Ageing Study I
No full textAIMS: Diabetes is associated with increased mortality in older adults, but the specific contributions of diabetes-associated clinical conditions and of increasing hyperglycaemia to mortality risk are unknown. We evaluated whether cardiovascular disease, comorbidities, or degree of hyperglycaemia, particularly severe hyperglycaemia, affected diabetes-related mortality risk in older, disabled women. METHODS: Six-year mortality follow-up of a random sample of 576 disabled women (aged 65-101 years), recruited from the Medicare eligibility list in Baltimore (MD, USA). All-cause and cardiovascular mortality were evaluated by diabetes status: no diabetes; diabetes with mild, moderate, and severe hyperglycaemia [defined by tertiles of glycosylated haemoglobin (GHB) among women with diabetes]. RESULTS: Diabetes with mild, moderate, and severe hyperglycaemia was associated with an increased hazard rate (HR) for all-cause mortality, even after adjustment for demographics, risks for cardiovascular disease, cardiovascular and non-cardiovascular conditions, and other known mortality risks. A dose-response effect was suggested [mild hyperglycaemia, HR 1.81, 95% confidence interval (CI) 1.03, 3.17; moderate hyperglycaemia, HR 2.02, 95% CI 1.34, 3.57; severe hyperglycaemia, HR 2.22, 95% CI 1.17, 4.25]. Women with diabetes had a significantly increased HR for non-cardiovascular death, but not for cardiovascular death, compared with those without diabetes. CONCLUSIONS: Diabetes, whether characterized by mild, moderate or severe hyperglycaemia, appears to be an independent risk factor for excess mortality in older disabled women and this risk may increase with increasing hyperglycaemia. This mortality risk is not completely explained by vascular complications, and involves non-cardiovascular deaths. Risks and benefits of diabetes management, including glycaemic control and management of vascular and other comorbidities, should be studied in older people with complications and comorbidities
What constitutes normal hemoglobin concentration in community-dwelling disabled older women?
No full textOBJECTIVES: To examine the associations between hemoglobin (Hb) concentration and (1) 5-year all-cause mortality and (2) serum erythropoietin (EPO), as the basis for the identification of data-driven thresholds, and to assess the clinical relevance of mildly low Hb. DESIGN: Prospective study. SETTING: Population based. PARTICIPANTS: Community-dwelling women aged 65 and older with moderate-to-severe disability--Women's Health and Aging Study I, Baltimore, Maryland, 1992-2000. METHODS: Proportional hazards regression was used to model the relationship between baseline Hb (available for 686 subjects) and time to death. A generalized linear model was used to assess the cross-sectional association between Hb and EPO in 641 subjects. RESULTS: A curvilinear slope of steady mortality decrease up to the Hb threshold of 13.9 g/dL was observed. Hb of 11 g/dL was independently associated with greater mortality than the World Health Organization (WHO) low-normal cutoff of Hb of 12 g/dL (hazard ratio (HR)=1.2, 95% confidence interval (CI)=1.1-1.4), whereas Hb of 14 g/dL was linked to 24% lower mortality (HR=0.76, 95% CI=0.63-0.92), after comprehensive adjustment for major health status and disease-burden indicators. A curvilinear, statistically significant slope of steady EPO decrease with increasing Hb up to the threshold of 14.3 g/dL was consistently observed. CONCLUSION: The meaningfully lower mortality risk with higher Hb levels provides empirical evidence against the notion that Hb currently perceived as mildly low is clinically benign. Furthermore, the mortality risk gradient observed even within the WHO normal Hb range suggests that Hb levels higher than what is currently recommended might offer clinical advantage. The relationship between Hb and EPO provided supporting physiological evidence for this hypothesis
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