Universality classes for horizon instabilities

We introduce a notion of universality classes for the Gregory-Laflamme instability and determine, in the supergravity approximation, the stability of a variety of solutions, including the non-extremal D3-brane, M2-brane, and M5-brane. These three non-dilatonic branes cross over from instability to stability at a certain non-extremal mass. Numerical analysis suggests that the wavelength of the shortest unstable mode diverges as one approaches the cross-over point from above, with a simple critical exponent which is the same in all three cases.Comment: 23 pages, latex2e, 4 figure

Techniques for Enhancing and Maintaining Electrical Efficiency of Photovoltaic Systems

Demand for electricity generation from solar energy, which is a clean and renewable resource, is increasing day by day. It is desirable that the panel surface temperature is not excessively hot while generating electricity with PVT panels. High temperature causes thermal degradation and panel electric efficiency decrease. There are many studies in the literature about active thermal cooling of PVT panels used for electricity generation as well as for storing thermal energy. In this study, a review was made on methods developed to increase the thermal and electrical efficiencies of PVT panels

Multibody Multipole Methods

A three-body potential function can account for interactions among triples of particles which are uncaptured by pairwise interaction functions such as Coulombic or Lennard-Jones potentials. Likewise, a multibody potential of order $n$ can account for interactions among $n$-tuples of particles uncaptured by interaction functions of lower orders. To date, the computation of multibody potential functions for a large number of particles has not been possible due to its $O(N^n)$ scaling cost. In this paper we describe a fast tree-code for efficiently approximating multibody potentials that can be factorized as products of functions of pairwise distances. For the first time, we show how to derive a Barnes-Hut type algorithm for handling interactions among more than two particles. Our algorithm uses two approximation schemes: 1) a deterministic series expansion-based method; 2) a Monte Carlo-based approximation based on the central limit theorem. Our approach guarantees a user-specified bound on the absolute or relative error in the computed potential with an asymptotic probability guarantee. We provide speedup results on a three-body dispersion potential, the Axilrod-Teller potential.Comment: To appear in Journal of Computational Physic

Peritoneal Fluid Analysis of the Newborn Calves with Intestinal Atresia - a Clinical Approach

Background: Anomalies and fetal problems are encountered in all animals. Intestinal atresia is a congenital anomaly of both humans and animals. Intestinal atresia has four morphological types, and they can be observed in jejunum, ileum, cecum, colon, rectum and anus (type I: mucosal atresia, type II: atretic ends separated by fibrous cord, type III: atretic ends separated by a “V” shaped mesenteric gap or atretic end coil like an “apple peel”, type IV: multiple atresia). In calves, it is also commonly encountered; it is still a question to be replied about the exact prognosis of the patients with intestinal atresia. Thus, the main objective of the present study was to evaluate peritoneal fluid analysis results of calves with intestinal atresia.Materials, Methods & Results: Twenty-two calves were presented with abdominal distension and lack of defecation. Clinical and radiological findings pointed out the intestinal atresia. Blood samples were collected for routine hematological and serum total protein (TP) analysis. Peritoneal fluids were aspirated with sterile technique from the caudal abdomen, and biochemical features, cell contents and microbiological cultures of the peritoneal fluids were analyzed. Following to preoperative, surgical and necropsy findings, intestinal atresia were diagnosed as type II, III and IV in calves. Neutrophilic leukocytosis was observed in calves with type IV intestinal atresia. Red blood cells and platelet counts were determined in the peritoneal fluids. TP and density values of the peritoneal fluid were high in all cases. These results pointed the presence of the acute infection and peritonitis. Statistical comparison of each parameter showed that there was no significant difference between the types of intestinal atresia. Microbiologically, fecal origin bacteria were cultured in 12 calves.Discussion: In general, four types of intestinal atresia are encountered in calves, and all types are fatal pathologies; thus, surgery should urgently be planned as soon as diagnostic work-ups are completed after birth. Peritoneal fluid analysis is a useful diagnostic choice because changes in the peritoneal fluid parameters help to diagnosis of the intra-abdominal pathology. Intestinal atresia as more common anomaly in Holstein, Jersey and Montafon breed calves. In animals with intestinal atresia, surgical treatment is not usually recommended due to economic reasons and small chance of postoperative success. Long-term survival rate of surgically treated animals depends on the type of intestinal atresia and applied surgical technique. Atresia recti and ani may occur simultaneously with atresia coli, and all atresias (atresia coli, ani, recti or ani et recti) can be successfully treated by surgery. Continuous distention of the large intestinal segments leads to ischemia, necrosis, peritonitis and bowel perforation. Peritoneal fluid analysis should include the classic parameters for diagnosis, but these analyses are often insufficient to identify the etiology or pathogenesis of the disease. An increase in total WBC count and percentage of the neutrophil cells in the peritoneal fluid indicate the acute infectious origin inflammation. Additional parameters in the peritoneal fluid analysis have been established to improve diagnostic precision and specific information. Presence or absence of the bacteria in the peritoneal fluid samples is important to characterize the transudate and exudate. Changings in the peritoneal fluid values does not related to type of the intestinal atresia in calves

Intrinsic Gaussian processes on complex constrained domains

We propose a class of intrinsic Gaussian processes (in-GPs) for interpolation, regression and classification on manifolds with a primary focus on complex constrained domains or irregular shaped spaces arising as subsets or submanifolds of R, R2, R3 and beyond. For example, in-GPs can accommodate spatial domains arising as complex subsets of Euclidean space. in-GPs respect the potentially complex boundary or interior conditions as well as the intrinsic geometry of the spaces. The key novelty of the proposed approach is to utilise the relationship between heat kernels and the transition density of Brownian motion on manifolds for constructing and approximating valid and computationally feasible covariance kernels. This enables in-GPs to be practically applied in great generality, while existing approaches for smoothing on constrained domains are limited to simple special cases. The broad utilities of the in-GP approach is illustrated through simulation studies and data examples

Stability analysis of surface ion traps

Motivated by recent developments in ion trap design and fabrication, we investigate the stability of ion motion in asymmetrical, planar versions of the classic Paul trap. The equations of motion of an ion in such a trap are generally coupled due to a nonzero relative angle $\theta$ between the principal axes of RF and DC fields, invalidating the assumptions behind the standard stability analysis for symmetric Paul traps. We obtain stability diagrams for the coupled system for various values of $\theta$, generalizing the standard $q$-$a$ stability diagrams. We use multi-scale perturbation theory to obtain approximate formulas for the boundaries of the primary stability region and obtain some of the stability boundaries independently by using the method of infinite determinants. We cross-check the consistency of the results of these methods. Our results show that while the primary stability region is quite robust to changes in $\theta$, a secondary stability region is highly variable, joining the primary stability region at the special case of $\theta=45^{\circ}$, which results in a significantly enlarged stability region for this particular angle. We conclude that while the stability diagrams for classical, symmetric Paul traps are not entirely accurate for asymmetric surface traps (or for other types of traps with a relative angle between the RF and DC axes), they are safe in the sense that operating conditions deemed stable according to standard stability plots are in fact stable for asymmetric traps, as well. By ignoring the coupling in the equations, one only underestimates the size of the primary stability region

Controlling trapping potentials and stray electric fields in a microfabricated ion trap through design and compensation

Recent advances in quantum information processing with trapped ions have demonstrated the need for new ion trap architectures capable of holding and manipulating chains of many (>10) ions. Here we present the design and detailed characterization of a new linear trap, microfabricated with scalable complementary metal-oxide-semiconductor (CMOS) techniques, that is well-suited to this challenge. Forty-four individually controlled DC electrodes provide the many degrees of freedom required to construct anharmonic potential wells, shuttle ions, merge and split ion chains, precisely tune secular mode frequencies, and adjust the orientation of trap axes. Microfabricated capacitors on DC electrodes suppress radio-frequency pickup and excess micromotion, while a top-level ground layer simplifies modeling of electric fields and protects trap structures underneath. A localized aperture in the substrate provides access to the trapping region from an oven below, permitting deterministic loading of particular isotopic/elemental sequences via species-selective photoionization. The shapes of the aperture and radio-frequency electrodes are optimized to minimize perturbation of the trapping pseudopotential. Laboratory experiments verify simulated potentials and characterize trapping lifetimes, stray electric fields, and ion heating rates, while measurement and cancellation of spatially-varying stray electric fields permits the formation of nearly-equally spaced ion chains.Comment: 17 pages (including references), 7 figure