3,626 research outputs found
Casimir effect of electromagnetic field in Randall-Sundrum spacetime
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
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
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
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
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
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
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
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 .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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