Vacuum polarization in two-dimensional static spacetimes and dimensional reduction

We obtain an analytic approximation for the effective action of a quantum scalar field in a general static two-dimensional spacetime. We apply this to the dilaton gravity model resulting from the spherical reduction of a massive, non-minimally coupled scalar field in the four-dimensional Schwarzschild geometry. Careful analysis near the event horizon shows the resulting two-dimensional system to be regular in the Hartle-Hawking state for general values of the field mass, coupling, and angular momentum, while at spatial infinity it reduces to a thermal gas at the black-hole temperature.Comment: REVTeX 4, 23 pages. Accepted by PRD. Minor modifications from original versio

Desflurane in modern anaesthetic practice:walking on thin ice(caps)?

The third-generation volatile anaesthetic agents desflurane and sevoflurane were introduced into clinical practice in the 1990s in response to the perceived need for rapid return of consciousness after ambulatory surgery. Initially marketed by two competing pharmaceutical companies, their relative merits have been debated for three decades. Of the two, desflurane has a lower solubility in blood and therefore the fastest offset, providing a rapid emergence, which is more notable in obese patients and after prolonged anaesthesia. Furthermore, some authorities (including the US Food and Drug Administration [FDA]) have deemed desflurane to be more suitable than sevoflurane for low-flow anaesthesia, as it undergoes only negligible metabolism and minimal reaction with soda lime. However, desflurane has several well-known disadvantages, including a pungent odour (making it a respiratory irritant), lower potency, and environmental impacts related to its manufacture, administration, and discharge into the atmosphere, calling into question its continued use as a general anaesthetic agent

The Dimensional-Reduction Anomaly in Spherically Symmetric Spacetimes

In D-dimensional spacetimes which can be foliated by n-dimensional homogeneous subspaces, a quantum field can be decomposed in terms of modes on the subspaces, reducing the system to a collection of (D-n)-dimensional fields. This allows one to write bare D-dimensional field quantities like the Green function and the effective action as sums of their (D-n)-dimensional counterparts in the dimensionally reduced theory. It has been shown, however, that renormalization breaks this relationship between the original and dimensionally reduced theories, an effect called the dimensional-reduction anomaly. We examine the dimensional-reduction anomaly for the important case of spherically symmetric spaces.Comment: LaTeX, 19 pages, 2 figures. v2: calculations simplified, references adde

An approximate solution of the MHD Falkner-Skan flow by Hermite functions pseudospectral method

Based on a new approximation method, namely pseudospectral method, a solution for the three order nonlinear ordinary differential laminar boundary layer Falkner-Skan equation has been obtained on the semi-infinite domain. The proposed approach is equipped by the orthogonal Hermite functions that have perfect properties to achieve this goal. This method solves the problem on the semi-infinite domain without truncating it to a finite domain and transforming domain of the problem to a finite domain. In addition, this method reduces solution of the problem to solution of a system of algebraic equations. We also present the comparison of this work with numerical results and show that the present method is applicable.Comment: 15 pages, 4 figures; Published online in the journal of "Communications in Nonlinear Science and Numerical Simulation

Phospholipid anaysis of extant microbiota for monitoring in situ bioremediation effectiveness

Two sites undergoing bioremediation were studied using the signature lipid biomarker (SLB) technique. This technique isolates microbial lipid moieties specifically related to viable biomass and to both prokaryotic and eukaryotic biosynthetic pathways. The first site was a South Pacific atoll heavily contaminated with petroleum hydrocarbons. The second site was a mine waste reclamation area. The SLB technique was applied to quantitate directly the viable biomass, community structure, and nutritional/physiological status of the microbiota in the soils and subsurface sediments of these sites. All depths sampled at the Kwajalein Atoll site showed an increase in biomass that correlated with the co-addition of air, water, and nutrients. Monoenoic fatty acids increased in abundance with the nutrient amendment, which suggested an increase in gram-negative bacterial population. Ratios of specific phospholipid fatty acids indicative of nutritional stress decreased with the nutrient amendment. Samples taken from the mine reclamation site showed increases in total microbial biomass and in Thiobacillus biomass in the plots treated with lime and bactericide, especially when a cover soil was added. The plot treated with bactericide and buffered lime without the cover soil showed some decrease in Thiobacillus numbers, but was still slightly higher than that observed in the control plots

Inflammatory Markers and Onset of Cardiovascular Events: Results from the Health ABC Study

Background - Inflammation plays an important role in cardiovascular disease. The aim of this study is to investigate the predictive value of several inflammatory markers on the incidence of cardiovascular events in well-functioning older persons. Methods and Results - The subjects were 2225 participants 70 to 79 years old, without baseline cardiovascular disease, who were enrolled in the Health, Aging, and Body Composition study. Incident coronary heart disease (CHD), stroke, and congestive heart failure (CHF) events were detected during an average follow-up of 3.6 years. Blood levels of interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor-\uce\ub1 (TNF-\uce\ub1) were assessed. After adjustment for potential confounders, IL-6 was significantly associated with all outcomes (CHD events, per IL-6 SD increase: RR, 1.27; 95% CI, 1.10 to 1.48; stroke events, per IL-6 SD increase: RR, 1.45; 95% CI, 1.12 to 1.86; CHF events, per IL-6 SD increase: RR, 1.72; 95% CI, 1.40 to 2.12). TNF-\uce\ub1 showed significant associations with CHD (per TNF-\uce\ub1 SD increase: RR, 1.22; 95% CI, 1.04 to 1.43) and CHF (per TNF-\uce\ub1 SD increase: RR, 1.59; 95% CI, 1.30 to 1.95) events. CRP was significantly associated with CHF events (per CRP SD increase: RR, 1.48; 95% CI, 1.23 to 1.78). A composite summary indicator of inflammation showed a strong association with incident cardiovascular events, with an especially high risk if all 3 inflammatory markers were in the highest tertile. Conclusions - Findings suggest that inflammatory markers are independent predictors of cardiovascular events in older persons

Microstructural analysis of collagen and elastin fibres in the kangaroo articular cartilage reveals a structural divergence depending on its local mechanical environment

Objective: To assess the microstructure of the collagen and elastin fibres in articular cartilage under different natural mechanical loading conditions and determine the relationship between the microstructure of collagen and its mechanical environment. Method: Articular cartilage specimens were collected from the load bearing regions of the medial femoral condyle and the medial distal humerus of adult kangaroos. The microstructure of collagen and elastin fibres of these specimens was studied using laser scanning confocal microscopy (LSCM) and the orientation and texture features of the collagen were analysed using ImageJ. Results: A zonal arrangement of collagen was found in kangaroo articular cartilage: the collagen fibres aligned parallel to the surface in the superficial zone and ran perpendicular in the deep zone. Compared with the distal humerus, the collagen in the femoral condyle was less isotropic and more clearly oriented, especially in the superficial and deep zones. The collagen in the femoral condyle was highly heterogeneous, less linear and more complex. Elastin fibres were found mainly in the superficial zone of the articular cartilage of both femoral condyle and distal humerus. Conclusions: The present study demonstrates that the collagen structure and texture of kangaroo articular cartilage is joint-dependent. This finding emphasizes the effects of loading on collagen development and suggests that articular cartilage with high biochemical and biomechanical qualities could be achieved by optimizing joint loading, which may benefit cartilage tissue engineering and prevention of joint injury. The existence of elastin fibres in articular cartilage could have important functional implications

Clinical delineation and natural history of the PIK3CA-related overgrowth spectrum.

Somatic mutations in the phosphatidylinositol/AKT/mTOR pathway cause segmental overgrowth disorders. Diagnostic descriptors associated with PIK3CA mutations include fibroadipose overgrowth (FAO), Hemihyperplasia multiple Lipomatosis (HHML), Congenital Lipomatous Overgrowth, Vascular malformations, Epidermal nevi, Scoliosis/skeletal and spinal (CLOVES) syndrome, macrodactyly, and the megalencephaly syndrome, Megalencephaly-Capillary malformation (MCAP) syndrome. We set out to refine the understanding of the clinical spectrum and natural history of these phenotypes, and now describe 35 patients with segmental overgrowth and somatic PIK3CA mutations. The phenotypic data show that these previously described disease entities have considerable overlap, and represent a spectrum. While this spectrum overlaps with Proteus syndrome (sporadic, mosaic, and progressive) it can be distinguished by the absence of cerebriform connective tissue nevi and a distinct natural history. Vascular malformations were found in 15/35 (43%) and epidermal nevi in 4/35 (11%) patients, lower than in Proteus syndrome. Unlike Proteus syndrome, 31/35 (89%) patients with PIK3CA mutations had congenital overgrowth, and in 35/35 patients this was asymmetric and disproportionate. Overgrowth was mild with little postnatal progression in most, while in others it was severe and progressive requiring multiple surgeries. Novel findings include: adipose dysregulation present in all patients, unilateral overgrowth that is predominantly left-sided, overgrowth that affects the lower extremities more than the upper extremities and progresses in a distal to proximal pattern, and in the most severely affected patients is associated with marked paucity of adipose tissue in unaffected areas. While the current data are consistent with some genotype-phenotype correlation, this cannot yet be confirmed

Academic requirements for Certificate of Completion of Training in surgical training: Consensus recommendations from the Association of Surgeons in Training/National Research Collaborative Consensus Group.

BACKGROUND: Surgical trainees are expected to demonstrate academic achievement in order to obtain their certificate of completion of training (CCT). These standards are set by the Joint Committee on Surgical Training (JCST) and specialty advisory committees (SAC). The standards are not equivalent across all surgical specialties and recognise different achievements as evidence. They do not recognise changes in models of research and focus on outcomes rather than process. The Association of Surgeons in Training (ASiT) and National Research Collaborative (NRC) set out to develop progressive, consistent and flexible evidence set for academic requirements at CCT. METHODS: A modified-Delphi approach was used. An expert group consisting of representatives from the ASiT and the NRC undertook iterative review of a document proposing changes to requirements. This was circulated amongst wider stakeholders. After ten iterations, an open meeting was held to discuss these proposals. Voting on statements was performed using a 5-point Likert Scale. Each statement was voted on twice, with ≥80% of votes in agreement meaning the statement was approved. The results of this vote were used to propose core and optional academic requirements for CCT. RESULTS: Online discussion concluded after ten rounds. At the consensus meeting, statements were voted on by 25 delegates from across surgical specialties and training-grades. The group strongly favoured acquisition of 'Good Clinical Practice' training and research methodology training as CCT requirements. The group agreed that higher degrees, publications in any author position (including collaborative authorship), recruiting patients to a study or multicentre audit and presentation at a national or international meeting could be used as evidence for the purpose of CCT. The group agreed on two essential 'core' requirements (GCP and methodology training) and two of a menu of four 'additional' requirements (publication with any authorship position, presentation, recruitment of patients to a multicentre study and completion of a higher degree), which should be completed in order to attain CCT. CONCLUSION: This approach has engaged stakeholders to produce a progressive set of academic requirements for CCT, which are applicable across surgical specialties. Flexibility in requirements whilst retaining a high standard of evidence is desirable