Massless Rotating Spacetimes in Four-Dimensional Horava Gravity

We study a particular exact solution for rotating spacetimes in four-dimensional Horava gravity, which has been proposed as a renormalizable gravity model without the ghost problem. We show that the massless Kerr spacetime or the massless Kerr-(A)dS spacetime in Einstein gravity is an exact solution in four-dimensional Horava for an arbitrary IR Lorentz-violation parameter lambda, but with an appropriate cosmological constant. In particular, for the massless topological Kerr-AdS black hole solution with the hyperbolic horizon topology or the massless Kerr-dS cosmological solution with the spherical horizon topology, there exist the ergosphere and the non-vanishing Hawking temperature, which imply the existence of negative mass black holes as well as positive mass spacetimes, by losing its mass from the massless ones via the Hawking radiation or Penrose process in the ergosphere.Comment: 10 pages, 3 figure

Competitors and Cooperators: A Micro‐Level Analysis of Regional Economic Development Collaboration Networks

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90044/1/j.1540-6210.2011.02501.x.pd

Effects of nanofluids containing graphene/graphene-oxide nanosheets on critical heat flux

The superb thermal conduction property of graphene establishes graphene as an excellent material for thermal management. In this paper, we selected graphene/graphene oxide nanosheets as the additives in nanofluids. The authors interestingly found that the highly enhanced critical heat flux (CHF) in the nanofluids containing graphene/graphene-oxide nanosheets (GON) cannot be explained by both the improved surface wettability and the capillarity of the nanoparticles deposition layer. Here we highlights that the GON nanofluid can be exploited to maximize the CHF the most efficiently by building up a characteristically ordered porous surface structure due to its own self-assembly characteristic resulting in a geometrically changed critical instability wavelength.open363

Low-power hybrid structure of digital matched filters for direct sequence spread spectrum systems

ABSTRACT 1 This paper presents a low-power structure of digital matched filters (DMFs), which is proposed for direct sequence spread spectrum systems. Traditionally, low-power approaches for DMFs are based on either the transposedform structure or the direct-form one. A new hybrid structure that employs the direct-form structure for local addition and the transposed-form structure for global addition is used to take advantages of both structures. For a 128-tap DMF, the proposed DMF that processes 32 addends a cycle consumes 46 % less power at the expense of 6 % area overhead as compared to the state-of-the-art low-power DM

Identification of New Potential APE1 Inhibitors by Pharmacophore Modeling and Molecular Docking

Apurinic/apyrimidinic endonuclease 1 (APE1) is an enzyme responsible for the initial step in the base excision repair pathway and is known to be a potential drug target for treating cancers, because its expression is associated with resistance to DNA-damaging anticancer agents. Although several inhibitors already have been identified, the identification of novel kinds of potential inhibitors of APE1 could provide a seed for the development of improved anticancer drugs. For this purpose, we first classified known inhibitors of APE1. According to the classification, we constructed two distinct pharmacophore models. We screened more than 3 million lead-like compounds using the pharmacophores. Hits that fulfilled the features of the pharmacophore models were identified. In addition to the pharmacophore screen, we carried out molecular docking to prioritize hits. Based on these processes, we ultimately identified 1,338 potential inhibitors of APE1 with predicted binding affinities to the enzyme

Reconstruction of Pretibial Defect Using Pedicled Perforator Flaps

BackgroundCoverage of defects of the pretibial area remains a challenge for surgeons. The difficulty comes from the limited mobility and availability of the overlying skin and soft tissue. We applied variable pedicled perforator flaps to overcome the disadvantages of local flaps and free flaps on the pretibial area.MethodsEight patients who had the defects in the anterior tibial area were enrolled. Retrospective data were obtained on patient demographics, cause, defect location, defect size, flap dimension, originating artery, pedicle length, pedicle rotation, complication, and postoperative result. The raw surface created following the flap elevation was covered with a split thickness skin graft.ResultsPosterior tibial artery-based perforator flaps were used in five cases and peroneal artery-based perforator flaps in three cases. The mean age was 54.3 and the mean period of follow-up was 6 months. The average size of the flaps was 63.8 cm2, with a range of 18 to 135 cm2. There were no major complications. No patients had any newly developed functional deficit of the lower leg.ConclusionsWe suggest that pedicled perforator flaps can be an alternative treatment modality for covering pretibial defects as a simple, safe and versatile procedure

Improvement of Mechanical Properties of UV-curable Resin for High-aspect Ratio Microstructures Fabricated in Microstereolithography

Recently, microstructures fabricated using microstereolithography technology have been used in the biological, medical and mechanical fields. Microstereolithography can fabricate real 3D microstructures with fine features, although there is presently a limited number of materials available for use in the process. Deformation of the fine features on a fabricated microstructure remains a critical issue for successful part fabrication, and part deformation can occur during rinsing or during fabrication as a result of fluid flow forces that occur during movement of mechanical parts of the system. Deformation can result in failure to fabricate a particular feature by breaking the feature completely, spatial deflection of the feature, or attaching the feature to neighboring microstructures. To improve mechanical strength of fabricated microstructures, a clay nanocomposite can be used. In particular, a high-aspect ratio microstructure can be fabricated without distortion using photocurable liquid resin containing a clay nanocomposite. In this paper, a clay nanocomposite was blended with a photocurable liquid resin to solve the deformation problem that occurs during fabrication and rinsing. An optimal mixture ratio of a clay nanocomposite was found through tensile testing and the minimal allowable distance between microstructures was found through fabrication experimentation. Finally, using these results, high-aspect ratio microstructures were fabricated using a clay nanocomposite resin without distortion

Corneal cell viability and structure after transcorneal freezing–thawing in the human cornea

Purpose: Although cryotherapy has long been used to eradicate corneal lesions, there have been no reports of adverse effects of cryotherapy on human corneas. We performed this study to evaluate and characterize ultrastructural damage to the human cornea following the transcorneal freezing-and-thawing procedure. Methods: Seven human donor corneas were randomly divided into three groups. 1, 2, and 3 repetitive freezing-and-thawing procedures were respectively applied to donor corneas in each group. A cryoprobe was cooled to-80°C, and placed on the anterior surface 1.5 mm central to the limbus for 3 seconds. Samples were then allowed to spontaneously defrost. A cornea without the treatment was used as a control. Samples were evaluated through hematoxylin & eosin staining, TUNEL assay, and electron microscopy. Results: After transcorneal cryoinjury, it was observed that corneal endothelial cells were lost and Descemet's membrane was denuded where the cryoprobe was applied. Corneal stromal cells were damaged, and the damage was more marked in the posterior stroma. The extent of damage increased with an increasing number of freezing-thawing repetitions. In contrast, corneal epithelial cells showed no cryo-induced damage, and Bowman's layer remained intact in all groups. Conclusions: The susceptibility to transcorneal cryo-injury differed among the corneal layers; the corneal endothelium was most susceptible, and the epithelium was least susceptible. Caution would thus be advised in regard to the potential damage in corneal endothelium when treating patients with corneal lesions using transcorneal cryotherapy.©2010 Oh et al, publisher and licensee Dove Medical Press Ltd.Y

Generating nearly single-cycle pulses with increased intensity and strongly asymmetric pulses of petawatt level

Generation of petawatt-class pulses with a nearly single-cycle duration or with a strongly asymmetric longitudinal profile using a thin plasma layer are investigated via particle-in-cell simulations and the analytical flying mirror model. It is shown that the transmitted pulses having a duration as short as about 4 fs (1.2 laser cycles) or one-cycle front (tail) asymmetric pulses with peak intensity of about 10(21) W/cm(2) can be produced by optimizing system parameters. Here, a new effect is found for the shaping of linearly polarized laser pulses, owing to which the peak amplitude of the transmitted pulse becomes larger than that of the incoming pulse, and intense harmonics are generated. Characteristics of the transmitting window are then studied for different parameters of laser pulse and plasma layer. For a circular polarization, it is shown that the flying mirror model developed for shaping laser pulses with ultrathin foils can be successfully applied to plasma layers having a thickness of about the laser wavelength, which allows the shape of the transmitted pulse to be analytically predicted.open6