3,626 research outputs found

    Casimir effect of electromagnetic field in Randall-Sundrum spacetime

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    We study the finite temperature Casimir effect on a pair of parallel perfectly conducting plates in Randall-Sundrum model without using scalar field analogy. Two different ways of interpreting perfectly conducting conditions are discussed. The conventional way that uses perfectly conducting condition induced from 5D leads to three discrete mode corrections. This is very different from the result obtained from imposing 4D perfectly conducting conditions on the 4D massless and massive vector fields obtained by decomposing the 5D electromagnetic field. The latter only contains two discrete mode corrections, but it has a continuum mode correction that depends on the thicknesses of the plates. It is shown that under both boundary conditions, the corrections to the Casimir force make the Casimir force more attractive. The correction under 4D perfectly conducting condition is always smaller than the correction under the 5D induced perfectly conducting condition. These statements are true at any temperature.Comment: 20 pages, 4 figure

    Agricultural land conversion in Northwest Iran

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    Agricultural Land Conversion (ALC) has been introduced as one of the most important factors affecting ecosystem. This type of conversion has led to several challenges in agricultural development and human life. Monitoring ALC plays a crucial role when dealing with such challenges. The main objective of this study was to monitor the trend of ALC in the Qazvin province located in Northwest Iran from 1990 to 2010 using remote sensing data. The results showed that 44,845 ha of agricultural lands (3.03% of the total agricultural lands of the province) were converted to non-agricultural lands, of which, 32,033 and 10,243 ha (2.16% and 0.69% of total agricultural lands of the province), were respectively transformed to saline lands and urban areas and infrastructures. Our projection for 2030 shows that among other uses, the conversion of agricultural lands to the saline lands and urban areas and infrastructures will stay most likely. However, the conversion probability for irrigated and orchard lands to urban areas and infrastructures will be more than the saline lands while the conversion probability for dry and rangelands to the saline lands will be more than urban areas and infrastructures

    Gravity is an important determinant of Oxygenation during One-Lung Ventilation

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    The role of gravity in the redistribution of pulmonary blood flow during one-lung ventilation (OLV) has recently been questioned. To address this controversial but clinically important issue we used an experimental approach that allowed us to differentiate the effects of gravity from the effects of hypoxic pulmonary vasoconstriction on arterial oxygenation during OLV in patients scheduled for thoracic surger

    Metabolic Changes after Urinary Diversion

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    Urinary diversion is performed on a regular basis in urological practice. Surgeons tend to underestimate the metabolic effects of any type of diversion. From the patient's perspective, diarrhea is the most bothersome complaint after urinary diversion. This might be accompanied by malabsorption syndromes, such as vitamin B12 deficiency. Electrolyte abnormalities can occur frequently such as hyperchloremic metabolic acidosis, or less frequently such as hypokalemia, hypocalcaemia, and hypomagnesaemia. Bone health is at risk in patients with urinary diversion. Some patients might benefit from vitamin D and calcium supplementation. Many patients are also subject to urinary calculus formation, both at the level of the upper urinary tract as in intestinal reservoirs. Urinary diversion can affect hepatic metabolism, certainly in the presence of urea-splitting bacteria. The kidney function has to be monitored prior to and lifelong after urinary diversion. Screening for reversible causes of renal deterioration is an integral part of the followup

    Motor symptoms in Parkinson's disease: A unified framework

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    Parkinson’s disease (PD) is characterized by a range of motor symptoms. Besides the cardinal symptoms (akinesia and bradykinesia, tremor and rigidity), PD patients show additional motor deficits, including: gait disturbance, impaired handwriting, grip force and speech deficits, among others. Some of these motor symptoms (e.g., deficits of gait, speech, and handwriting) have similar clinical profiles, neural substrates, and respond similarly to dopaminergic medication and deep brain stimulation (DBS). Here, we provide an extensive review of the clinical characteristics and neural substrates of each of these motor symptoms, to highlight precisely how PD and its medical and surgical treatments impact motor symptoms. In conclusion, we offer a unified framework for understanding the range of motor symptoms in PD. We argue that various motor symptoms in PD reflect dysfunction of neural structures responsible for action selection, motor sequencing, and coordination and execution of movement

    A 0.821-ratio purely combinatorial algorithm for maximum k-vertex cover in bipartite graphs

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    We study the polynomial time approximation of the max k-vertex cover problem in bipartite graphs and propose a purely combinatorial algorithm that beats the only such known algorithm, namely the greedy approach. We present a computer-assisted analysis of our algorithm, establishing that the worst case approximation guarantee is bounded below by 0.821. © Springer-Verlag Berlin Heidelberg 2016

    Effectiveness of adalimumab for rheumatoid arthritis in patients with a history of TNF-antagonist therapy in clinical practice

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    Objective. To evaluate the effectiveness and safety of adalimumab in patients with rheumatoid arthritis (RA) who previously discontinued tumour necrosis factor (TNF) antagonists for any reason in clinical practice. Methods. ReAct (Research in Active Rheumatoid Arthritis) was a large, open-label trial that enrolled adults with active RA who had previously been treated with traditional disease-modifying anti-rheumatic drugs or biological response modifiers. Patients selfadministered adalimumab 40 mg subcutaneously every other week for 12 weeks and were allowed to enter an optional long-term extension phase. Measures of adalimumab effectiveness included American College of Rheumatology (ACR) and European League Against Rheumatism (EULAR) response criteria, Disease Activity Score 28 (DAS28) and the Health Assessment Questionnaire Disability Index (HAQ DI). Results. Of 6610 patients, 899 had a history of etanercept and/or infliximab therapy; these patients experienced substantial clinical benefit from adalimumab treatment. At week 12, 60% of patients had an ACR20 and 33% had an ACR50 response; 76% had a moderate and 23% had a good EULAR response. In addition, 12% achieved a DAS28 < 2.6, indicating clinical remission, and 13% achieved a HAQ DI score < 0.5. The allergic adverse event rate, regardless of relationship to adalimumab, was 6.5/100-patient-years (PYs) in previously TNF antagonist-exposed patients and 4.3/100-PYs in TNF antagonist naive patients. A multiple regression analysis indicated no statistically significantly increased risk of serious infections in patients who received prior TNF antagonists compared with TNF antagonist naive patients. Conclusion. In typical clinical practice, adalimumab was effective and well-tolerated in patients with RA previously treated with etanercept and/or infliximab

    Approaching criticality via the zero dissipation limit in the abelian avalanche model

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    The discrete height abelian sandpile model was introduced by Bak, Tang & Wiesenfeld and Dhar as an example for the concept of self-organized criticality. When the model is modified to allow grains to disappear on each toppling, it is called bulk-dissipative. We provide a detailed study of a continuous height version of the abelian sandpile model, called the abelian avalanche model, which allows an arbitrarily small amount of dissipation to take place on every toppling. We prove that for non-zero dissipation, the infinite volume limit of the stationary measure of the abelian avalanche model exists and can be obtained via a weighted spanning tree measure. We show that in the whole non-zero dissipation regime, the model is not critical, i.e., spatial covariances of local observables decay exponentially. We then study the zero dissipation limit and prove that the self-organized critical model is recovered, both for the stationary measure and for the dynamics. We obtain rigorous bounds on toppling probabilities and introduce an exponent describing their scaling at criticality. We rigorously establish the mean-field value of this exponent for d>4d > 4.Comment: 46 pages, substantially revised 4th version, title has been changed. The main new material is Section 6 on toppling probabilities and the toppling probability exponen
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