1,406 research outputs found

    Asymptotic Analysis of a Loss Model with Trunk Reservation I: Trunks Reserved for Fast Traffic

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    We consider a model for a single link in a circuit-switched network. The link has C circuits, and the input consists of offered calls of two types, that we call primary and secondary traffic. Of the C links, R are reserved for primary traffic. We assume that both traffic types arrive as Poisson arrival streams. Assuming that C is large and R=O(1), the arrival rate of primary traffic is O(C), while that of secondary traffic is smaller, of the order O(C). The holding times of the primary calls are assumed to be exponentially distributed with unit mean. Those of the secondary calls are exponentially distributed with a large mean, that is, O(C). Thus, the primary calls have fast arrivals and fast service, compared to the secondary calls. The loads for both traffic types are comparable (O(C)), and we assume that the system is “critically loaded”; that is, the system's capacity is approximately equal to the total load. We analyze asymptotically the steady state probability that n1 (resp., n2) circuits are occupied by primary (resp., secondary) calls. In particular, we obtain two-term asymptotic approximations to the blocking probabilities for both traffic types

    Bounds on dissipation in magnetohydrodynamic problems in plane shear geometry

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    The total dissipation rate for magnetohydrodynamic (MHD) flows in plane geometry with both velocity and magnetic shear is studied. For some boundary conditions it is shown that the lower bound on the dissipation rate is achieved by the equivalent of Stokes flow for MHD. Using the background method [Doering and Constantin, Phys. Rev. Lett. 69, 1648 (1992)] upper bounds for the dissipation rate are calculated. For a shear layer, with both velocity and magnetic shear, parameter dependence of the upper bound is obtained. As a by-product of this calculation, an energy stability domain is calculated. A sheet pinch is also studied, and it is shown that the upper bound tends to zero as the resistivity tends to zero. Thus, an antiturbulence result is obtained. © 2003 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70246/2/PHPAEN-10-11-4314-1.pd

    Public Navigation Rights in New York State: Questions and Answers

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    The public right of navigation has existed in New York as a common law right since New York became a state. This right allows vessels of all kinds, including small boats and canoes, to navigate for commercial and recreational purposes on New York\u27s waterways that are navigable-in-fact. Legally, the courts have said that the State of New York, in accordance with public trust doctrine, holds an easement on such waterways in trust for the people of the state, making them public highways for navigational purposes. The privately-owned bed and banks of such waterways are subject to this easement or servitude when used for purposes of navigation. This paper describes and explains this public right

    Human metabolism and elimination of the anthocyanin, cyanidin-3-glucoside: a 13C-tracer study

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    BACKGROUND: Evidence suggests that the consumption of anthocyanin-rich foods beneficially affects cardiovascular health; however, the absorption, distribution, metabolism, and elimination (ADME) of anthocyanin-rich foods are relatively unknown. OBJECTIVE: We investigated the ADME of a (13)C5-labeled anthocyanin in humans. DESIGN: Eight male participants consumed 500 mg isotopically labeled cyanidin-3-glucoside (6,8,10,3',5'-(13)C5-C3G). Biological samples were collected over 48 h, and (13)C and (13)C-labeled metabolite concentrations were measured by using isotope-ratio mass spectrometry and liquid chromatography-tandem mass spectrometry. RESULTS: The mean +/- SE percentage of (13)C recovered in urine, breath, and feces was 43.9 +/- 25.9% (range: 15.1-99.3% across participants). The relative bioavailability was 12.38 +/- 1.38% (5.37 +/- 0.67% excreted in urine and 6.91 +/- 1.59% in breath). Maximum rates of (13)C elimination were achieved 30 min after ingestion (32.53 +/- 14.24 mug(13)C/h), whereas (13)C-labeled metabolites peaked (maximum serum concentration: 5.97 +/- 2.14 mumol/L) at 10.25 +/- 4.14 h. The half-life for (13)C-labeled metabolites ranged between 12.44 +/- 4.22 and 51.62 +/- 22.55 h. (13)C elimination was greatest between 0 and 1 h for urine (90.30 +/- 15.28 mug/h), at 6 h for breath (132.87 +/- 32.23 mug/h), and between 6 and 24 h for feces (557.28 +/- 247.88 mug/h), whereas the highest concentrations of (13)C-labeled metabolites were identified in urine (10.77 +/- 4.52 mumol/L) and fecal samples (43.16 +/- 18.00 mumol/L) collected between 6 and 24 h. Metabolites were identified as degradation products, phenolic, hippuric, phenylacetic, and phenylpropenoic acids. CONCLUSION: Anthocyanins are more bioavailable than previously perceived, and their metabolites are present in the circulation fo

    PI3K activation is associated with intracellular sodium/iodide symporter protein expression in breast cancer

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    Background: The sodium/iodide symporter (NIS) is a membrane glycoprotein mediating active iodide uptake in the thyroid gland and is the molecular basis for radioiodide imaging and therapeutic ablation of thyroid carcinomas. NIS is expressed in the lactating mammary gland and in many human breast tumors, raising interest in similar use for diagnosis and treatment. However, few human breast tumors have clinically evident iodide uptake ability. We previously identified PI3K signaling as important in NIS upregulation in transgenic mouse models of breast cancer, and the PI3K pathway is commonly activated in human breast cancer. Methods: NIS expression, subcellular localization, and function were analyzed in MCF-7 human breast cancer cells and MCF-7 cells stably or transiently expressing PI3K p110alpha subunit using Western blot of whole cell lysate, cell surface biotinylation Western blot and immunofluorescence, and radioiodide uptake assay, respectively. NIS localization was determined in a human breast cancer tissue microarray using immunohistochemical staining (IHC) and was correlated with preexisting pAkt IHC data. Statistical analysis consisted of Student's t-test (in vitro studies) or Fisher's Exact Test (in vivo correlational studies). Results: In this study, we demonstrate that PI3K activation in MCF-7 human mammary carcinoma cells leads to expression of underglycosylated NIS lacking cell surface trafficking necessary for iodide uptake ability. PI3K activation also appears to interfere with cell surface trafficking of exogenous NIS as well as all-trans retinoic acid-induced endogenous NIS. A correlation between NIS expression and upregulation of PI3K signaling was found in a human breast cancer tissue microarray. Conclusion: Thus, the PI3K pathway likely plays a major role in the discordance between NIS expression and iodide uptake in breast cancer patients. Further study is warranted to realize the application of NIS-mediated radioiodide ablation in breast cancer

    SBC2009-204872 CIRCUMFERENTIAL CYCLIC STRAIN IN PATIENTS WITH DESCENDING THORACIC AORTIC ANEURYSMS: IMPLICATIONS FOR ENDOVASCULAR DEVICE DESIGN

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    INTRODUCTION Endovascular graft (EVG) therapy has emerged as a promising alternative to open surgical repair of thoracic aortic aneurysms. However, the long-term durability of thoracic endovascular repair (TEVAR) remains uncertain due to complications such as incomplete aneurysm exclusion (endoleaks), migration, and stent fracture and collapse. These complications could likely be reduced if the biomechanical environment of the thoracic aorta was better understood. Currently, there are three FDA approved EVGs for treatment of descending thoracic aortic aneurysms (DTAA), but the range of bench-top testing mechanisms for these devices are limited. Despite many advances in medical imaging and analysis techniques, relatively little is known about the wall dynamics of the thoracic aorta, particularly in patients with aneurysms. While one recent study reports diameter change before and after endovascular therap

    Potential profit gains from improving pasture productivity on New Zealand South Island high-country farms

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    Soil acidity combined with low levels of key nutrients on New Zealand hill-country farms are limiting factors for legume establishment/growth. However, legumes are a critical component of these farms as they provide nitrogen and high-quality feed. A farm-systems model was developed to estimate the impact of targeted fertiliser and lime application, combined with sowing clover, on whole-farm productivity and profitability. A base model was developed that incorporated 17 years’ worth of Beef + Lamb NZ survey data for Class 1: South Island Farms. This base model was then used investigate two lime-application/oversowing models where part of the modelled high-country farm was targeted for improvement: (1) Conservative, i.e. 0.6% farm area; and (2) Aggressive, i.e. 2.8% farm area. Three scenarios to utilise the additional pasture grown were then investigated for each model by: (a) increasing ewe numbers; (b) increasing ewe performance (lambing percentage); and (c) increasing liveweight gain of stock. Scenario 2a, generated the highest profitability level (Earnings before Interest Tax and Rent, EBITR 58,870)abovethebasemodelbutbecamelessfinanciallyattractivewhenthetwoyearsrequiredtobuildthematernaleweflockwerefactoredin.Scenarios2cand1bgeneratedincreasesinprofitability(EBITR)between58,870) above the base model but became less financially attractive when the two years required to build the maternal ewe flock were factored in. Scenarios 2c and 1b generated increases in profitability (EBITR) between 33,310 and $41,290 above the base model. Variation in product prices, production levels and time to develop the final farm-management system would also influence the productivity and profitability of the scenarios. Environmental aspects, infrastructure and staff availability would affect the suitability of the development for individual farming businesses

    Tocotrienols-induced inhibition of platelet thrombus formation and platelet aggregation in stenosed canine coronary arteries

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    <p>Abstract</p> <p>Background</p> <p>Dietary supplementation with tocotrienols has been shown to decrease the risk of coronary artery disease. Tocotrienols are plant-derived forms of vitamin E, which have potent anti-inflammatory, antioxidant, anticancer, hypocholesterolemic, and neuroprotective properties. Our objective in this study was to determine the extent to which tocotrienols inhibit platelet aggregation and reduce coronary thrombosis, a major risk factor for stroke in humans. The present study was carried out to determine the comparative effects of α-tocopherol, α-tocotrienol, or tocotrienol rich fraction (TRF; a mixture of α- + γ- + δ-tocotrienols) on <it>in vivo platelet thrombosis </it>and <it>ex vivo </it>platelet aggregation (PA) after intravenous injection in anesthetized dogs, by using a mechanically stenosed circumflex coronary artery model (Folts' cyclic flow model).</p> <p>Results</p> <p>Collagen-induced platelet aggregation (PA) in platelet rich plasma (PRP) was decreased markedly after treatment with α-tocotrienol (59%; <b><it>P </it></b>< 0.001) and TRF (92%; <b><it>P </it></b>< 0.001). α-Tocopherol treatment was less effective, producing only a 22% (<b><it>P </it></b>< 0.05) decrease in PA. Adenosine diphosphate-induced (ADP) PA was also decreased after treatment with α-tocotrienol (34%; <b><it>P </it></b>< 0.05) and TRF (42%; <b><it>P </it></b>< 0.025). These results also indicate that intravenously administered tocotrienols were significantly better than tocopherols in inhibiting cyclic flow reductions (CFRs), a measure of the acute platelet-mediated thrombus formation. Tocotrienols (TRF) given intravenously (10 mg/kg), abolished CFRs after a mean of 68 min (range 22 -130 min), and this abolition of CFRs was sustained throughout the monitoring period (50 - 160 min).</p> <p>Next, pharmacokinetic studies were carried out and tocol levels in canine plasma and platelets were measured. As expected, α-Tocopherol treatment increased levels of total tocopherols in post- vs pre-treatment specimens (57 vs 18 μg/mL in plasma, and 42 vs 10 μg/mL in platelets). However, treatment with α-tocopherol resulted in slightly decreased levels of tocotrienols in post- vs pre-treatment samples (1.4 vs 2.9 μg/mL in plasma and 2.3 vs 2.8 μg/mL in platelets). α-Tocotrienol treatment increased levels of both tocopherols and tocotrienols in post- vs pre-treatment samples (tocopherols, 45 vs 10 μg/mL in plasma and 28 vs 5 μg/mL in platelets; tocotrienols, 2.8 vs 0.9 μg/mL in plasma and 1.28 vs 1.02 μg/mL in platelets). Treatment with tocotrienols (TRF) also increased levels of tocopherols and tocotrienols in post- vs pre-treatment samples (tocopherols, 68 vs 20 μg/mL in plasma and 31.4 vs 7.9 μg/mL in platelets; tocotrienols, 8.6 vs 1.7 μg/mL in plasma and 3.8 vs 3.9 μg/mL in platelets).</p> <p>Conclusions</p> <p>The present results indicate that intravenously administered tocotrienols inhibited acute platelet-mediated thrombus formation, and collagen and ADP-induced platelet aggregation. α-Tocotrienols treatment induced increases in α-tocopherol levels of 4-fold and 6-fold in plasma and platelets, respectively. Interestingly, tocotrienols (TRF) treatment induced a less pronounced increase in the levels of tocotrienols in plasma and platelets, suggesting that intravenously administered tocotrienols may be converted to tocopherols. Tocotrienols, given intravenously, could potentially prevent pathological platelet thrombus formation and thus provide a therapeutic benefit in conditions such as stroke and myocardial infarction.</p

    High-Sensitivity C Reactive Protein: Associations with Cardiovascular Risk Factors and Tracking in Female Adolescents and Young Adults

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    Objective. We assessed adolescent anthropometry, lipids, insulin, glucose, and blood pressures to identify factors associated with high-sensitivity C-reactive protein (hsCRP) and its tracking in young adults. Methods. Ten-year prospective study of 589 schoolgirls, 321 black, 268 white. Results. HsCRP did not differ (P > .08) by race or oral contraceptive use. HsCRP tracked from age 16 to 25 (r = 0.77), 16 to 26 (r = 0.50), 24 to 26 (r = 0.66), and 25 to 26 (r = 0.71), all P ≤ .02. By stepwise regression, at age 16, waist circumference accounted for 44.8% of hsCRP variance; BMI accounted for 33.1%, 34.4%, and 31.1% at ages 24, 25, and 26, P < .0001 for all. Changes in cholesterol and BMI were associated with change in hsCRP from age 24–26 (partial R2 = 12.3%  P < .0001, 6.6%  P = .0012). Changes in BMI and triglyceride (partial R2 = 8.5%  P = .0001, 3.3%, P = .0045) were associated with change in hsCRP from age 25 to 26. Conclusions. HsCRP tracks from age 16 to 26, with BMI, waist circumference, and cholesterol as major determinants
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