Anisotropic evolution of 5D Friedmann-Robertson-Walker spacetime

We examine the time evolution of the five-dimensional Einstein field equations subjected to a flat, anisotropic Robertson-Walker metric, where the 3D and higher-dimensional scale factors are allowed to dynamically evolve at different rates. By adopting equations of state relating the 3D and higher-dimensional pressures to the density, we obtain an exact expression relating the higher-dimensional scale factor to a function of the 3D scale factor. This relation allows us to write the Friedmann-Robertson-Walker field equations exclusively in terms of the 3D scale factor, thus yielding a set of 4D effective Friedmann-Robertson-Walker field equations. We examine the effective field equations in the general case and obtain an exact expression relating a function of the 3D scale factor to the time. This expression involves a hypergeometric function and cannot, in general, be inverted to yield an analytical expression for the 3D scale factor as a function of time. When the hypergeometric function is expanded for small and large arguments, we obtain a generalized treatment of the dynamical compactification scenario of Mohammedi [Phys.Rev.D 65, 104018 (2002)] and the 5D vacuum solution of Chodos and Detweiler [Phys.Rev.D 21, 2167 (1980)], respectively. By expanding the hypergeometric function near a branch point, we obtain the perturbative solution for the 3D scale factor in the small time regime. This solution exhibits accelerated expansion, which, remarkably, is independent of the value of the 4D equation of state parameter w. This early-time epoch of accelerated expansion arises naturally out of the anisotropic evolution of 5D spacetime when the pressure in the extra dimension is negative and offers a possible alternative to scalar field inflationary theory.Comment: 20 pages, 4 figures, paper format streamlined with main results emphasized and details pushed to appendixes, current version matches that of published versio

Bridges and Bandits on the Road to the New Jerusalem: A Study of the Correlation Between Immigration and Terrorism

In late January of 2017, President Trump signed an executive order banning non-American citizens traveling into the United States from seven different countries. The title of the order was, “Protecting the Nation From Foreign Terrorist Entry Into the United States.” As implied, the stated purpose was to limit the number of immigrants in order to avoid future attacks. For the order to serve a purpose, immigration must play a role in terrorism. Thus, the essential point of disagreement is whether a connection exists between the influx of migrants—especially those from terror-prone nations—and the occurrence of terrorist activity in the receiving nation. In this study, we attempt to discover if a link exists between immigration from terror-prone nations and terrorism by examining the current literature and using data to analyze the levels of immigration as well as the incidents of terrorism in six countries. The hypothesis of this research project is that as countries receive increased levels of asylum seekers from terror-prone nations they will experience a corresponding increase in the numbers of terror attacks within the nation. Our basic premise is that immigrant flows form a social bridge, transplanting cultures, ideologies, as well as individuals between the sending and receiving nations. Thus, we are seeking to find out if there is a strong correlation between immigration and terrorism. The null hypothesis, then, is that there is no correlation between immigration from terror-prone nations and the occurrence of terror attacks within a particular nation. Our research shows that, as predicted in our hypothesis, increased terrorism is linked to increased migration from terror-prone nations and regions. The data from Germany and Turkey display a strong positive correlation between asylum-seeker migration and incidents of terrorism. It is worth noting that immigration alone is not enough to predict a rise in terrorist attacks. Rather, immigration is only one of many factors that may lead to increased terrorism. However, it is our contention that immigration from terror-producing regions is a significant predictor of increased terrorist activity

A Web-based archive of systematic review data

Systematic reviews have become increasingly critical to informing healthcare policy; however, they remain a time-consuming and labor-intensive activity. The extraction of data from constituent studies comprises a significant portion of this effort, an activity which is often needlessly duplicated, such as when attempting to update a previously conducted review or in reviews of overlapping topics

Bistatic Observations of the Ocean Surface with HF Radar, Satellite and Airborne Receivers

Embargo of 24 months from date of publishing on accepted manuscript version. Link to publisher's version:https://ieeexplore.ieee.org/document/8232298/Copyright notice:“© © 20xx IEEE policy"A new concept has been developed which can view vast regions of the Earth's surface. Ground HF transmissions are reflected by the ionosphere to illuminate the ocean over a few thousand kilometers. HF receivers detect the radio waves scattered by the sea and land surface. Using the theory of radio wave scatter from ocean surfaces, the HF data is then processed to yield the directional wave-height spectrum of the ocean. This technique has several advantages over existing remote sensing methods. A large area of the ocean can be sampled to yield the wave-height characteristics with high, km-scale resolution. The wave height spectrum can be directly compared with temporal frequency spectrum obtained with buoys at specific points in the ocean volume. Furthermore, the technique uses HF waves which penetrate the dense rain found in hurricanes

Clinical and operative predictors of outcomes of carotid endarterectomy

ObjectiveThe net benefit for patients undergoing carotid endarterectomy is critically dependent on the risk of perioperative stroke and death. Information about risk factors can aid appropriate selection of patients and inform efforts to reduce complication rates. This study identifies the clinical, radiographic, surgical, and anesthesia variables that are independent predictors of deaths and stroke following carotid endarterectomy.MethodsA retrospective cohort study of patients undergoing carotid endarterectomy in 1997 and 1998 by 64 surgeons in 6 hospitals was performed (N = 1972). Detailed information on clinical, radiographic, surgical, anesthesia, and medical management variables and deaths or strokes within 30 days of surgery were abstracted from inpatient and outpatient records. Multivariate logistic regression models identified independent clinical characteristics and operative techniques associated with risk-adjusted rates of combined death and nonfatal stroke as well as all strokes.ResultsDeath or stroke occurred in 2.28% of patients without carotid symptoms, 2.93% of those with carotid transient ischemic attacks, and 7.11% of those with strokes (P < .0001). Three clinical factors increased the risk-adjusted odds of complications: stroke as the indication for surgery (odds ratio [OR], 2.84; 95% confidence interval [CI] = 1.55-5.20), presence of active coronary artery disease (OR, 3.58; 95% CI = 1.53-8.36), and contralateral carotid stenosis ≥50% (OR, 2.32; 95% CI = 1.33-4.02). Two surgical techniques reduced the risk-adjusted odds of death or stroke: use of local anesthesia (OR, 0.30; 95% CI = 0.16-0.58) and patch closure (OR, 0.43; 95% CI = 0.24-0.76).ConclusionsInformation about these risk factors may help physicians weigh the risks and benefits of carotid endarterectomy in individual patients. Two operative techniques (use of local anesthesia and patch closure) may lower the risk of death or stroke

Bistatic Observations of the Ocean Surface with HF Radar, Satellite and Airborne Receivers

Accepted manuscript file. Published version available at https://ieeexplore.ieee.org/document/8232298A new concept has been developed which can view vast regions of the Earth’s surface. Ground HF transmissions are reflected by the ionosphere to illuminate the ocean over a few thousand kilometers. HF receivers detect the radio waves scattered by the sea and land surface. Using the theory of radio wave scatter from ocean surfaces, the HF data is then processed to yield the directional wave-height spectrum of the ocean. This technique has several advantages over existing remote sensing methods. A large area of the ocean can be sampled to yield the wave-height characteristics with high, km-scale resolution. The wave height spectrum can be directly compared with temporal frequency spectrum obtained with buoys at specific points in the ocean volume. Furthermore, the technique uses HF waves which penetrate the dense rain found in hurricanes

Novel role for thioredoxin reductase-2 in mitochondrial redox adaptations to obesogenic diet and exercise in heart and skeletal muscle

Increased fatty acid availability and oxidative stress are physiological consequences of exercise (Ex) and a high-fat, high-sugar (HFHS) diet. Despite these similarities, the global effects of Ex are beneficial, whereas HFHS diets are largely deleterious to the cardiovascular system. The reasons for this disparity are multifactorial and incompletely understood. We hypothesized that differences in redox adaptations following HFHS diet in comparison to exercise may underlie this disparity, particularly in mitochondria. Our objective in this study was to determine mechanisms by which heart and skeletal muscle (red gastrocnemius, RG) mitochondria experience differential redox adaptations to 12 weeks of HFHS diet and/or exercise training (Ex) in rats. Surprisingly, both HFHS feeding and Ex led to contrasting effects in heart and RG, in that mitochondrial H2O2 decreased in heart but increased in RG following both HFHS diet and Ex, in comparison to sedentary animals fed a control diet. These differences were determined to be due largely to increased antioxidant/anti-inflammatory enzymes in the heart following the HFHS diet, which did not occur in RG. Specifically, upregulation of mitochondrial thioredoxin reductase-2 occurred with both HFHS and Ex in the heart, but only with Ex in RG, and systematic evaluation of this enzyme revealed that it is critical for suppressing mitochondrial H2O2 during fatty acid oxidation. These findings are novel and important in that they illustrate the unique ability of the heart to adapt to oxidative stress imposed by HFHS diet, in part through upregulation of thioredoxin reductase-2. Furthermore, upregulation of thioredoxin reductase-2 plays a critical role in preserving the mitochondrial redox status in the heart and skeletal muscle with exercise.Funding from the National Institutes of Health, United State