Strongly bounded groups and infinite powers of finite groups

We define a group as strongly bounded if every isometric action on a metric space has bounded orbits. This latter property is equivalent to the so-called uncountable strong cofinality, recently introduced by G. Bergman. Our main result is that G^I is strongly bounded when G is a finite, perfect group and I is any set. This strengthens a result of Koppelberg and Tits. We also prove that omega_1-existentially closed groups are strongly bounded.Comment: 10 pages, no figure. Versions 1-3 were entitled "Uncountable groups with Property (FH)". To appear in Comm. Algebr

Optimization of the OpenFlow Controller in Wireless Environments for Enhancing Mobility

OpenRoads or OpenFlow Wireless is an open-source platform for deploying an innovative and realistic strategy for different services in wireless networks. It provides a wireless extension for OpenFlow. It is developed to support existing Wireless Local Area Networks (WLANs) and Worldwide Interoperability for Microwave Access (WiMAX) networks. It can provide several mobility managers and run them concurrently in the network including hard handover, informed handover, n-casting and Hoolock. However, the provided mobility support for flow-based routing, where flows of one source taking different paths through multiple wireless access points or base stations, is not simple and hard to be deployed in the traditional routing algorithms. This paper proposes an intelligent mobility enhancement control and then develops an algorithm to decide which neighbor switches need to be selected for the installation of new flow entries and to allocate the appropriate idle-timeout for the selected switches. The proposed approach provides a simple solution to solve the user mobility problem in wireless OpenFlow environments which can handle the fast migration of user addresses (e.g. IP addresses) between several wireless access points and base stations. This approach leads to improvement in the end users' experience

Developing an application based on OpenFlow to enhance mobile IP networks

Mobile Internet Protocol (IP) has been developed to maintain permanent IP addresses for mobile users while they are moving from one point to another where the Mobile Terminal (MT) device will have two IP addresses: a static home address and a care-of address which will be changed and re-attached at each point of the movement of the MT. However, a location update message is required to be sent to the home agent for each new connection. This will potentially increase the handoff latency and leads to high load on the global Internet. This paper presents the concepts and the challenges of Mobile IP networks and then proposes the use of OpenFlow approach as an alternate transport mechanism to perform routing and to provide network connectivity for Mobile IP networks. The proposed application determines calculations and reroutes the subsequent packets. OpenFlow aims to optimize routing path and handoff performance by using controller's application and exchanges controllers' information. © 2013 IEEE

A Novel Survey Tool to Quantify the Degree and Duration of STEMI Regionalization Across California.

IntroductionCalifornia has been a global leader in regionalization efforts for time-critical medical conditions. A total of 33 local emergency medical service agencies (LEMSAs) exist, providing an organized EMS framework across the state for almost 40 years. We sought to develop a survey tool to quantify the degree and duration of ST-elevation myocardial infarction (STEMI) regionalization over the last decade in California.MethodsThe project started with the development of an 8-question survey tool via a multi-disciplinary expert consensus process. Next, the survey tool was distributed at the annual meeting of administrators and medical directors of California LEMSAs to get responses valid through December, 2014. The first scoring approach was the Total Regionalization Score (TRS) and used answers from all 8 questions. The second approach was called the Core Score, and it focused on only 4 survey questions by assuming that the designation of STEMI Receiving Centers must have occurred at the beginning of any LEMSA's regionalization effort. Scores were ranked and grouped into tertiles.ResultsAll 33 LEMSAs in California participated in this survey. The TRS ranged from 15 to 162. The Core Score range was much narrower, from 2 to 30. In comparing TRS and Core Score rankings, the top-tertiles were quite similar. More rank variation occurred between mid- and low-tertiles.ConclusionThis study evaluated the degree and duration of STEMI network regionalization from 2004 to 2014 in California, and ranked 33 LEMSAs into tertiles based upon their TRS and their Core Score. Successful application of the 8-item survey and ranking strategies across California suggests that this approach can be used to assess regionalization in other states or countries around the world

Low disordered, stable, and shallow germanium quantum wells: a playground for spin and hybrid quantum technology

Buried-channel semiconductor heterostructures are an archetype material platform to fabricate gated semiconductor quantum devices. Sharp confinement potential is obtained by positioning the channel near the surface, however nearby surface states degrade the electrical properties of the starting material. In this paper we demonstrate a two-dimensional hole gas of high mobility ($5\times 10^{5}$ cm$^2$/Vs) in a very shallow strained germanium channel, which is located only 22 nm below the surface. This high mobility leads to mean free paths $\approx6 \mu m$, setting new benchmarks for holes in shallow FET devices. Carriers are confined in an undoped Ge/SiGe heterostructure with reduced background contamination, sharp interfaces, and high uniformity. The top-gate of a dopant-less field effect transistor controls the carrier density in the channel. The high mobility, along with a percolation density of $1.2\times 10^{11}\text{ cm}^{-2}$, light effective mass (0.09 m$_e$), and high g-factor (up to $7$) highlight the potential of undoped Ge/SiGe as a low-disorder material platform for hybrid quantum technologies

Passive smoking in the etiology of non-syndromic orofacial clefts:a systematic review and meta-analysis

Background Studies have found a consistent positive association between maternal smoking and nonsyndromic orofacial clefts (NSOFC). However, no comprehensive assessment of the association between NSOFC and passive smoking has been undertaken. This systematic review and meta-analysis explores the relationship between maternal passive smoking and NSOFC, and compares the associations between passive and active smoking. Methods and Findings Search strategy, inclusion / exclusion criteria, and data extraction from studies reporting maternal passive smoking and NSOFC was implemented without language restrictions. Risks of bias in the identified studies were assessed and this information was used in sensitivity analyses to explain heterogeneity. Meta-analysis and meta-regression of the extracted data were performed. Egger's test was used to test for small study effects. Fourteen eligible articles were identified. Maternal passive smoking exposure was associated with a twofold increase in risk of NSOFC (odds ratio: 2.11, 95% confidence interval: 1.54-2.89); this was apparent for both cleft lip with and without palate (OR: 2.05, 95% CI: 1.27-3.3) and cleft palate (OR: 2.11, 95% CI: 1.23-3.62). There was substantial heterogeneity between studies. In the studies that provided data enabling crude and adjusted odd ratios to be compared, adjustment for potential confounders attenuated the magnitude of association to about a 1.5-fold increase in risk. Conclusion Overall, maternal passive smoking exposure results in a 1.5 fold increase in risk of NSOFC, similar to the magnitude of risk reported for active smoking, but there is marked heterogeneity between studies. This heterogeneity is not explained by differences in the distribution of cleft types, adjustment for covariates, broad geographic region, or study bias/quality. This thorough meta-analysis provides further evidence to minimize exposure to environmental tobacco smoke in policy making fora and in health promotion initiatives.</p

Using an ICN Approach to Support Multiple Controllers in OpenFlow

Abstract — Information Centric Networking (ICN) is an innovative direction for next generation networks. It is a concept of networking paradigm which is considered as a new technique for future search activities. ICN is based on caching contents in several nodes and replicating these contents. It provides contents requested by users from the nearest node instead of creating a communication channel between sender and receiver just for calling information. This paper aims to scale OpenFlow network in traffic engineering by reducing number of transactions, predicting and pre-populating flow entries using the ICN approach. In addition, the paper shows the advantages of implementing ICN designs within OpenFlow. The proposed approach aims to implement ICN concepts to enhance OpenFlow network. This will enable the deployment of networking solutions in the existing network infrastructure and will lead to more flexibility in OpenFlow network. In addition, OpenFlow will have a global management view for all connected networks managed by different controllers. The proposed solution can fulfill current management and utilization of network demands. The paper then debates the implementation of ICN’s design and features based on Software Defined Networking (SDN)