Authorized licensed use limited to: University of Texas at Arlington

ABSTRACT In this article, we focus on the use of radio frequency wireless LANs, as opposed to infrared wireless systems. For radio frequency wireless LANs, the availability of unlicensed spectrum is a significant enabler. In the United States, it was the Federal Communications Commission's rule change, first published in 1985 (modified in 1990) allowing unlicensed spread spectrum use of the three industrial, scientific, and medical (ISM) frequency bands, that encouraged the development of a number of wireless technologies. Today, unlicensed wireless LAN products are available in all three of the ISM bands at 902-928 MHz,' 2.400-2.4835 GHz, and 5.725-5.850 GHz. As described later, the IEEE 802.11 committee makes use of the 2.4 GHz ISM band. The discussion that follows treats several types of emerging standards which impact wireless LAN systems. We begin with a description of two influential physical-and data-link-layer standards, IEEE 802.11 and HIPERLAN. Following this, we briefly examine some developments concerning the U.S. personal communication services (PCS) bands, future spectrum allocations, and wireless asynchronous transfer mode (ATM) systems. After describing these physical-and link-layer developments, we focus on the network layer. We discuss the extensions being made to the widely used Internet Protocol (IP) t o deal with mobility (wired or wireless). Finally, we describe some emerging standards for wireless link management in which interfaces are specified to provide wireless link information to protocol stacks and applications on the mobile client. In the conclusion, we speculate on future directions of wireless LAN systems. IEEE 802.1 1 WIRELESS LAN STANDARD he IEEE 802.11 committee has been working on the estab-T lishment of a standard for wireless LANs. Having begun its work in 1990, the 802.11 committee is nearing completion of the standard, which is expected to be finalized in mid-1996 Much of the standard appears to have reached final form at the current time (early 1996), so we can describe the main features of the architecture, the multiple physical layers, and the common medium access control (MAC) sublayer [1]. ARCHITECTURE We introduce the general architecture and terminology defined by the 802 11 committee [l]. As shown in 8

EFFECT OF EDUCATIONAL INTERVENTION MEASURES ON KNOWLEDGE ABOUT RABIES AND ITS PREVENTIVE MEASURES AMONG FINAL YEAR NURSING STUDENTS OF A TERTIARY CARE HOSPITAL IN CENTRAL INDIA

Background: Rabies continues to be a major public health challenge with around 55,000 deaths every year. Amongst the health care providers nursing personnel are often the first point of contact and hence need to be well trained in the management of rabies cases. Methods: The present study was an educational intervention study conducted among 100 final year nursing students of a Medical College Hospital to assess the knowledge regarding rabies and its transmission, first aid measures undertaken, and pre and post exposure prophylaxis measures employed to prevent the infection. Results: 66% of the students knew about the signs and symptoms of the disease, post intervention this increased to 87%. Knowledge regarding animal bites which transmit rabies improved by 86 % mode of transmission by 49 % and first aid measures undertaken following an animal bite by 12%. 15% of the students knew about the correct site and route of PEP; post intervention 91% knew about it, 87% increase was observed as regards the dose of vaccine to be administered and 73% students correctly knew about the PEP schedule post educational intervention. Knowledge regarding groups / individuals who need to receive pre-exposure prophylaxis increased by 33% and that of the schedule of pre-exposure prophylaxis by 53%. The mean pre-intervention score was 6.95 and mean post-intervention score was 13.51; the results being statistically significant. Conclusion: Substantial improvement in knowledge about the disease was noted amongst the nursing students following the educational intervention session

Albiglutide and cardiovascular outcomes in patients with type 2 diabetes and cardiovascular disease (Harmony Outcomes): a double-blind, randomised placebo-controlled trial

Background: Glucagon-like peptide 1 receptor agonists differ in chemical structure, duration of action, and in their effects on clinical outcomes. The cardiovascular effects of once-weekly albiglutide in type 2 diabetes are unknown. We aimed to determine the safety and efficacy of albiglutide in preventing cardiovascular death, myocardial infarction, or stroke. Methods: We did a double-blind, randomised, placebo-controlled trial in 610 sites across 28 countries. We randomly assigned patients aged 40 years and older with type 2 diabetes and cardiovascular disease (at a 1:1 ratio) to groups that either received a subcutaneous injection of albiglutide (30–50 mg, based on glycaemic response and tolerability) or of a matched volume of placebo once a week, in addition to their standard care. Investigators used an interactive voice or web response system to obtain treatment assignment, and patients and all study investigators were masked to their treatment allocation. We hypothesised that albiglutide would be non-inferior to placebo for the primary outcome of the first occurrence of cardiovascular death, myocardial infarction, or stroke, which was assessed in the intention-to-treat population. If non-inferiority was confirmed by an upper limit of the 95% CI for a hazard ratio of less than 1·30, closed testing for superiority was prespecified. This study is registered with ClinicalTrials.gov, number NCT02465515. Findings: Patients were screened between July 1, 2015, and Nov 24, 2016. 10 793 patients were screened and 9463 participants were enrolled and randomly assigned to groups: 4731 patients were assigned to receive albiglutide and 4732 patients to receive placebo. On Nov 8, 2017, it was determined that 611 primary endpoints and a median follow-up of at least 1·5 years had accrued, and participants returned for a final visit and discontinuation from study treatment; the last patient visit was on March 12, 2018. These 9463 patients, the intention-to-treat population, were evaluated for a median duration of 1·6 years and were assessed for the primary outcome. The primary composite outcome occurred in 338 (7%) of 4731 patients at an incidence rate of 4·6 events per 100 person-years in the albiglutide group and in 428 (9%) of 4732 patients at an incidence rate of 5·9 events per 100 person-years in the placebo group (hazard ratio 0·78, 95% CI 0·68–0·90), which indicated that albiglutide was superior to placebo (p<0·0001 for non-inferiority; p=0·0006 for superiority). The incidence of acute pancreatitis (ten patients in the albiglutide group and seven patients in the placebo group), pancreatic cancer (six patients in the albiglutide group and five patients in the placebo group), medullary thyroid carcinoma (zero patients in both groups), and other serious adverse events did not differ between the two groups. There were three (<1%) deaths in the placebo group that were assessed by investigators, who were masked to study drug assignment, to be treatment-related and two (<1%) deaths in the albiglutide group. Interpretation: In patients with type 2 diabetes and cardiovascular disease, albiglutide was superior to placebo with respect to major adverse cardiovascular events. Evidence-based glucagon-like peptide 1 receptor agonists should therefore be considered as part of a comprehensive strategy to reduce the risk of cardiovascular events in patients with type 2 diabetes. Funding: GlaxoSmithKline

Rapid real-time PCR assay for detecting Salmonella in raw and ready-to-eat meats

A real-time PCR assay was evaluated for the rapid detection (10 h) of Salmonella in meats using molecular beacon probes available as a commercial kit (iQ-Check, Bio-Rad laboratories). Raw (chicken, pork) and ready-to-eat (RTE) meats were artificially contaminated with Salmonella enterica serovar Typhimurium at the estimated level of 2 to 4 cells per 25 g. After 8 h of pre-enrichment in buffered peptone water, a molecular beacon-based PCR assay was performed to detect contamination in raw and RTE meats. The sensitivity and accuracy of the assay were compared with the conventional USDA microbiological procedure. Comparative evaluation of the USDA procedure with the rapid PCR assay for meat samples (n = 63) revealed 1 false negative pork sample with the PCR assay. All uninoculated controls (n = 34) but one sample were negative by both the 10-h PCR assay and the USDA procedure. Developing rapid pathogen detection methods with shorter pre-enrichment times (8-h) and real-time data monitoring capabilities will benefit the industry in preventing recall of contaminated meats by stopping the contaminated products from being introduced into the marketplace

Inoculation onto Solid Surfaces Protects Salmonella spp. during Acid Challenge: a Model Study Using Polyethersulfone Membranes

Salmonellae are the most frequently reported cause of outbreaks of food-borne gastroenteritis in the United States. In clinical trials, the oral infective dose (ID) for healthy volunteers was estimated to be approximately 1 million cells. However, in reports from various outbreaks, the ID of Salmonella species associated with solid foods was estimated to be as few as 100 cells. We found that fresh-cut produce surfaces not only provided suitable solid support for pathogen attachment but also played a critical role in increasing the acid tolerance of the pathogen. However the acidic nature of certain produce played no role in making salmonellae resistant to stomach acidity. Inoculation onto fresh-cut produce surfaces, as well as onto inert surfaces, such as polyethersulfone membranes and tissue paper, increased the survival of salmonellae during acid challenge (50 mM Na-citrate, pH 3.0; 37°C; 2 h) by 4 to 5 log units. Acid challenge experiments using cells inoculated onto polyethersulfone membranes provided a model system suitable for studying the underlying fundamentals of the protection that occurs when Salmonella strains are associated with solid foods. The surface-associated acid protection, which was observed in several Salmonella strains, required de novo protein synthesis and was independent of stationary-phase sigma transcription factor

Legume-rhizobium interactions: cowpea root exudate elicits faster nodulation response by rhizobium species

Preinfection events in legume-Rhizobium symbiosis were analyzed by studying the different nodulation behaviors of two rhizobial strains in cowpeas (Vigna sinensis). Log-phase cultures of Rhizobium sp. strain 1001, an isolate from the plant nodule, initiated host responses leading to infection within 2 h after inoculation, whereas log-phase cultures of Rhizobium sp. strain 32H1 took at least 7 h to trigger a discernible response. The delay observed with strain 32H1 could be eliminated by incubating the rhizobial suspension, before inoculation, for 4.5 h either in the cowpea rhizosphere/rhizoplane condition or in the root exudate of cowpea plants, grown without NH4+ in the rooting medium. The delay could not be eliminated by incubating the rhizobial suspension in the rooting medium of plants grown in the presence of 5 mM NH4+, indicating that there is a regulatory role of combined nitrogen in triggering preinfection events by the legume. The substance(s) in the root exudate which elicited the faster nodulation response by Rhizobium sp. strain 32H1 could be separated into a high-molecular-weight fraction by Sephadex G-100 gel filtration. The data support the notion that legume roots release substances that favor the development of rhizobial features essential for infection and nodulation

System Design Issues for Low-Power, Low-Cost Short Range Wireless Networking

The emergence of battery powered handheld devices as popular computing devices is presenting new challenges. Among the most important challenges is the need to provide a low cost, low power, indoor wireless networking access to handheld devices. The constraints posed by battery power and cost require a careful re-evaluation of system design issues at all layer of the protocol stack. In this paper, we present the design of a short range wire-less networking system called BlueSky which is being developed at IBM Research to address these challenges. We show that the optimization objectives for short range indoor wireless systems are quite different from those for traditional cellular wireless systems. We also argue that in the next millennium the primary op-timization criteria for the design of (short range) wireless systems will shift from the traditional spectral efficiency towards battery lifetime and cost