T-duality in the weakly curved background

We consider the closed string propagating in the weakly curved background which consists of constant metric and Kalb-Ramond field with infinitesimally small coordinate dependent part. We propose the procedure for constructing the T-dual theory, performing T-duality transformations along coordinates on which the Kalb-Ramond field depends. The obtained theory is defined in the non-geometric double space, described by the Lagrange multiplier $y_\mu$ and its $T$-dual $\tilde{y}_\mu$. We apply the proposed T-duality procedure to the T-dual theory and obtain the initial one. We discuss the standard relations between T-dual theories that the equations of motion and momenta modes of one theory are the Bianchi identities and the winding modes of the other

Urban and Transport Scaling: Northern Mesopotamia in the Late Chalcolithic and Bronze Age

Scaling methods have been applied to study modern urban areas and how they create accelerated, feedback growth in some systems while efficient use in others. For ancient cities, results have shown that cities act as social reactors that lead to positive feedback growth in socioeconomic measures. In this paper, we assess the relationship between settlement area expressed through mound area from Late Chalcolithic and Bronze Age sites and mean hollow way widths, which are remains of roadways, from the Khabur Triangle in northern Mesopotamia. The intent is to demonstrate the type of scaling and relationship present between sites and hollow ways, where both feature types are relatively well preserved. For modern roadway systems, efficiency in growth relative to population growth suggests roads should show sublinear scaling in relation to site size. In fact, similar to modern systems, such sublinear scaling results are demonstrated for the Khabur Triangle using available data, suggesting ancient efficiency in intensive transport growth relative to population levels. Comparable results are also achieved in other ancient Near East regions. Furthermore, results suggest that there could be a general pattern relevant for some small sites (0–2 ha) and those that have fewer hollow ways, where β, a measure of scaling, is on average low (≈ < 0.2). On the other hand, a second type of result for sites with many hollow ways (11 or more) and that are often larger suggests that β is greater (0.23–0.72), but still sublinear. This result could reflect the scale in which larger settlements acted as greater social attractors or had more intensive economic activity relative to smaller sites. The provided models also allow estimations of past roadway widths in regions where hollow ways are missing

Guidelines for management of ischaemic stroke and transient ischaemic attack 2008

This article represents the update of the European Stroke Initiative Recommendations for Stroke Management. These guidelines cover both ischaemic stroke and transient ischaemic attacks, which are now considered to be a single entity. The article covers referral and emergency management, Stroke Unit service, diagnostics, primary and secondary prevention, general stroke treatment, specific treatment including acute management, management of complications, and rehabilitation

Regional Evaluation of the Severity-Based Stroke Triage Algorithm for Emergency Medical Services Using Discrete Event Simulation

Background and Purpose: The Severity-Based Stroke Triage Algorithm for Emergency Medical Services endorses routing patients with suspected large vessel occlusion acute ischemic strokes directly to endovascular stroke centers (ESCs). We sought to evaluate different specifications of this algorithm within a region. Methods: We developed a discrete event simulation environment to model patients with suspected stroke transported according to algorithm specifications, which varied by stroke severity screen and permissible additional transport time for routing patients to ESCs. We simulated King County, Washington, and Mecklenburg County, North Carolina, distributing patients geographically into census tracts. Transport time to the nearest hospital and ESC was estimated using trafficbased travel times. We assessed undertriage, overtriage, transport time, and the number-needed-to-route, defined as the number of patients enduring additional transport to route one large vessel occlusion patient to an ESC. Results: Undertriage was higher and overtriage was lower in King County compared with Mecklenburg County for each specification. Overtriage variation was primarily driven by screen (eg, 13%-55% in Mecklenburg County and 10%-40% in King County). Transportation time specifications beyond 20 minutes increased overtriage and decreased undertriage in King County but not Mecklenburg County. A low-versus high-specificity screen routed 3.7× more patients to ESCs. Emergency medical services spent nearly twice the time routing patients to ESCs in King County compared with Mecklenburg County. Conclusions: Our results demonstrate how discrete event simulation can facilitate informed decision making to optimize emergency medical services stroke severity-based triage algorithms. This is the first step toward developing a mature simulation to predict patient outcomes