Gravitational charges of transverse asymptotically AdS spacetimes

Using Killing-Yano symmetries, we construct conserved charges of spacetimes that asymptotically approach to the flat or Anti-de Sitter spaces only in certain directions. In D dimensions, this allows one to define gravitational charges (such as mass and angular momenta densities) of p-dimensional branes/solitons or any other extended objects that curve the transverse space into an asymptotically flat or AdS one. Our construction answers the question of what kind of charges the antisymmetric Killing-Yano tensors lead to.Comment: 11 pages, no figures, REVTeX 4; version 2: important corrections made; version 3: one new paragraph and 2 references added, accepted for publication in PR

Godel-type Metrics in Various Dimensions II: Inclusion of a Dilaton Field

This is the continuation of an earlier work where Godel-type metrics were defined and used for producing new solutions in various dimensions. Here a simplifying technical assumption is relaxed which, among other things, basically amounts to introducing a dilaton field to the models considered. It is explicitly shown that the conformally transformed Godel-type metrics can be used in solving a rather general class of Einstein-Maxwell-dilaton-3-form field theories in D >= 6 dimensions. All field equations can be reduced to a simple "Maxwell equation" in the relevant (D-1)-dimensional Riemannian background due to a neat construction that relates the matter fields. These tools are then used in obtaining exact solutions to the bosonic parts of various supergravity theories. It is shown that there is a wide range of suitable backgrounds that can be used in producing solutions. For the specific case of (D-1)-dimensional trivially flat Riemannian backgrounds, the D-dimensional generalizations of the well known Majumdar-Papapetrou metrics of general relativity arise naturally.Comment: REVTeX4, 17 pp., no figures, a few clarifying remarks added and grammatical errors correcte

In Situ Stress Measurement During Aluminum Anodizing Using Phase-Shifting Curvature Interferometry

Stress measurements yield insight into technologically relevant deformation and failure mechanisms in electrodeposition, battery reactions, corrosion and anodic oxidation. Aluminum anodizing experiments were performed to demonstrate the effectiveness of phase-shifting curvature interferometry as a new technique for high-resolution in situ stress measurement. This method uses interferometry to monitor surface curvature changes, from which stress evolution is inferred. Phase-shifting of the reflected beams enhanced measurement sensitivity, and the separation of the optical path from the electrochemical cell in the present system provided increased stability. Curvature changes as small as 10−3 km−1 were detected, at least comparable to the resolution of state-of-the-art multiple beam deflectometry. It was demonstrated that small curvature change rates of 10−3 km−1s−1 could be reliably measured, indicating that the technique can be applied to bulk samples. The dependence of the stress change during anodizing on current density (tensile at low current density, but increasingly compressive at higher current densities) was quantitatively consistent with earlier multiple-beam deflectometry measurements. The close similarity between the results of these different high-resolution measurements helps to resolve conflicting reports of anodizing-induced stress changes found in the literature

Mining of vaccine-associated IFN-γ gene interaction networks using the Vaccine Ontology

Abstract Background Interferon-gamma (IFN-γ) is vital in vaccine-induced immune defense against bacterial and viral infections and tumor. Our recent study demonstrated the power of a literature-based discovery method in extraction and comparison of the IFN-γ and vaccine-mediated gene interaction networks. The Vaccine Ontology (VO) contains a hierarchy of vaccine names. It is hypothesized that the application of VO will enhance the prediction of IFN-γ and vaccine-mediated gene interaction network. Results In this study, 186 specific vaccine names listed in the Vaccine Ontology (VO) and their semantic relations were used for possible improved retrieval of the IFN-γ and vaccine associated gene interactions. The application of VO allows discovery of 38 more genes and 60 more interactions. Comparison of different layers of IFN-γ networks and the example BCG vaccine-induced subnetwork led to generation of new hypotheses. By analyzing all discovered genes using centrality metrics, 32 genes were ranked high in the VO-based IFN-γ vaccine network using four centrality scores. Furthermore, 28 specific vaccines were found to be associated with these top 32 genes. These specific vaccine-gene associations were further used to generate a network of vaccine-vaccine associations. The BCG and LVS vaccines are found to be the most central vaccines in the vaccine-vaccine association network. Conclusion Our results demonstrate that the combined usages of biomedical ontologies and centrality-based literature mining are able to significantly facilitate discovery of gene interaction networks and gene-concept associations. Availability VO is available at: http://www.violinet.org/vaccineontology; and the SVM edit kernel for gene interaction extraction is available at: http://www.violinet.org/ifngvonet/int_ext_svm.ziphttp://deepblue.lib.umich.edu/bitstream/2027.42/112600/1/13326_2011_Article_34.pd

Cavity polaritons in ZnO-based hybrid microcavities

Among wide-bandgap semiconductors, ZnO is a very attractive candidate for blue-ultraviolet lasers operating at room temperature owing to its large exciton binding energy and oscillator strength. Especially, ZnO-based microcavity structures are most conducive for polariton lasing at room temperature. We report the observation of cavitypolaritons in bulk ZnO-based hybrid microcavities at room temperature. The bulk ZnO-based hybrid microcavities are composed of 29 pairs of Al0.5Ga0.5N∕GaNdistributed Bragg reflector (DBR) at the bottom of the λ-thick cavity layer and eight pairs of SiO2∕Si3N4 DBR as the top mirror, which provided cavityQvalues of ∼100. Anticrossing behavior between the lower and upper polariton branches was observed at room temperature. From the polariton dispersion curve, the vacuum Rabi splitting was estimated to be ∼50meV. These results are promising toward the realization of ZnO-based microcavity polariton devices

Getting science to the citizen : 'food addiction' at the British Science Festival as a case study of interactive public engagement with high profile scientific controversy

Non peer reviewedPublisher PD

Value of preoperative spirometry to predict postoperative pulmonary complications

AbstractIn order to determine the incidence of postoperative pulmonary complications (POPC) and the value of preoperative spirometry to predict pulmonary complications after upper abdominal surgery, 24 women and 36 men (total 60 patients) were studied prospectively (mean age 48·3 years). On the day before the operation and for 15 days after the operation, each patients's respiratory status was assessed by clinical examination, chest radiography, spirometry and blood gas analysis, and patients were monitored for pulmonary complications by a chest physician and a surgeon independently. In this study, postoperative pulmonary complications developed in 21 (35%) patients (pneumonia in 10 patients, bronchitis in nine patients, atelectasis in one patient, pulmonary embolism in one patient). Of 31 patients with abnormal preoperative spirometry, 14 (45·2%) patients showed complications, whereas among 29 patients with normal preoperative spirometry, 7 (24·1%) patients showed complications (P<0·05). The incidence of POPC was higher in patients with advanced age, smoking, preoperative abnormal findings obtained from physical examination of the chest, higher ASA class and longer duration of operation. The sensitivity (0·76) and specificity (0·79) of abnormal preoperative findings obtained from physical examination to predict POPC were higher than abnormal preoperative spirometry (0·67 and 0·56 retrospectively). There was no significant difference between patients with and without pulmonary complications in regard to weight, serum albumin, type of incision, incidence of abnormal preoperative blood gases and duration of postoperative hospital stay. We conclude that POPC is still a serious cause of postoperative morbidity. Multiple risk factors include preoperative abnormal spirometry responsible for development of POPC. If used alone, spirometry has limited clinical value as a screening test to predict POPC after upper abdominal surgery

Stress evolution of anodic alumina films prior to the pore formation

Porous anodic oxide (PAO) films are grown by electrochemical oxidation of metals in a solution that dissolve the oxide. During the film formation, voltage increases linearly until the peak, then declines to steady-state value. PAO finds extensive usage as templates and substrates in many applications, such as solar cells and optical devices. However, the mechanism underlying the observed initiation and evolution of self-organized PAO structure is not understood. Recent studies on pore formation points out the role of plastic flow on pore initiation process [1–3]. In this study, we characterized stress profiles and its evolution during the film formation prior to the pore initiation. Phase-shifting curvature interferometry was used to monitor sample curvature change during film growth and subsequent dissolution. Oxide films were grown at constant current densities in 0.4 M H3PO4 until different thicknesses and subsequently current was turned off to dissolve grown oxide film. The stress profile of oxide film was revealed by in-situ monitoring the curvature change during dissolution of oxide film period after anodizing [4] . In addition, morphological evolution of oxide film during film growth was characterized using SEM. Oxide films growth until different thicknesses values up to onset of pore initiation instability. The measured stress change during film growth was in excellent agreement with prior measurements [5]. Measured stress profiles showed that for thin films \u3c20 nm, compressive stress was evenly dispersed through the thickness. However, for thicker films, the stress is concentrated within 20-nm thick layer near the solution interface. Transition in the stress profile coincides with oxide film thickness associated with initial roughening instability at the solution interface [6]. SEM images also showed that the first instability initiated at an oxide thickness of 20 nm with stable surface roughness pattern with a length scale of 20 nm. After the initial instability, the stress level near the solution interface became increasingly compressive as oxide film thickens. This behavior continued until the moment of self-ordered pore initiation when the both oxide thickness and the integrated oxide stress rapidly decreased to steady-state values. Morphological change during anodizing coincides with the stress transient, which could be attributed to the relaxation of elastic stress due to onset of plastic flow. Thus, plastic yielding in the oxide may induce a second instability mechanism involving pore initiation, leading to final self-ordered pore pattern. ACKNOWLEDGMENTS Support was provided by the National Science Foundation (CMMI-100748). REFERENCES [1] Garcia-Vergara, S.J., et al. Electrochim. Acta. 2006, 52, 681. [2] Houser, J.E., Hebert, K.R. Nature Mater. 2009, 8, 415. [3] Oh, J., Thompson, C.V. Electrochim. Acta. 2011, 56, 4044. [4] Çapraz, Ö.Ö., Shotriya, P., Hebert, K.R. J. Electrochem. Soc. 2014, 161, D256. [5] Çapraz, Ö.Ö., Hebert, K.R., Shotriya, P. J. Electrochem. Soc. 2013, 160, D501. [6] Hebert, K.R., et al. Nature Mater. 2012, 11, 162

Bargaining over a finite set of alternatives

We analyze bilateral bargaining over a finite set of alternatives. We look for “good” ordinal solutions to such problems and show that Unanimity Compromise and Rational Compromise are the only bargaining rules that satisfy a basic set of properties. We then extend our analysis to admit problems with countably infinite alternatives. We show that, on this class, no bargaining rule choosing finite subsets of alternatives can be neutral. When rephrased in the utility framework of Nash (1950), this implies that there is no ordinal bargaining rule that is finite-valued