Signaling game approach to improve the MAC protocol in the underwater wireless sensor networks

Underwater sensor networks (UWSNs) are instructed for critical applications like military surveillance and underwater oil spills that conducted in a very massive three‐dimensional (3‐D) space that needs many underwater nodes (UNs) to cover the target area. Those UNs are not easy to recharge and cannot exploit solar power. MAC protocols deployed for UWSN ought to consider the energy efficiency, so as, to extend the network lifetime with total connectivity and significant throughput. Terrestrial MAC protocols could not be used for UWSN due to long and unpredictable propagation delay. Consequently, the development of a new MAC protocol for the harsh environment as underwater is a challenging task. In this study, we focus on the deployment of TDMA in UWSN for this, two schemes entitled TDMA slot sharing (TSS) and free time slots reallocation (FTSR) are proposed. Received data stored in the buffer waiting for processing and forwarding might lead to an unlimited data transfer latency those results in the buffer overflow. Otherwise, free time slots appearing during the communication process resulting from dead nodes increase uselessly sleep time for the rest of the nodes. Both schemes based on signaling game are proposed to overcome those problems, TSS is used to enable the slot sharing between UNs during the communication process to reduce the buffer overflow. FTSR scheme aims to increase the throughput of UNs by allowing the reuse of free time slots. Numerical results conducted in this work show good improvement in the network performance concerning throughput.     

Atherosclerotic Calcification Detection: A Comparative Study of Carotid Ultrasound and Cone Beam CT

Background and Aim: Arterial calcification is often detected on ultrasound examination but its diagnostic accuracy is not well validated. The aim of this study was to determine the accuracy of carotid ultrasound B mode findings in detecting atherosclerotic calcification quantified by cone beam computed tomography (CBCT). Methods: We analyzed 94 carotid arteries, from 88 patients (mean age 70 ± 7 years, 33% females), who underwent pre-endarterectomy ultrasound examination. Plaques with high echogenic nodules and posterior shadowing were considered calcified. After surgery, the excised plaques were examined using CBCT, from which the calcification volume (mm³) was calculated. In cases with multiple calcifications the largest calcification nodule volume was used to represent the plaque. Carotid artery calcification by the two imaging techniques was compared using conventional correlations. Results: Carotid ultrasound was highly accurate in detecting the presence of calcification; with a sensitivity of 88.2%. Based on the quartile ranges of calcification volumes measured by CBCT we have divided plaque calcification into four groups: <8; 8–35; 36–70 and >70 mm³. Calcification volumes ≥8 were accurately detectable by ultrasound with a sensitivity of 96%. Of the 21 plaques with <8 mm³ calcification volume; only 13 were detected by ultrasound; resulting in a sensitivity of 62%. There was no difference in the volume of calcification between symptomatic and asymptomatic patients. Conclusion: Carotid ultrasound is highly accurate in detecting the presence of calcified atherosclerotic lesions of volume ≥8 mm³; but less accurate in detecting smaller volume calcified plaques. Further development of ultrasound techniques should allow better detection of early arterial calcification.     

Voronoi-based reverse nearest neighbor query processing on spatial networks

The use of Voronoi diagram has traditionally been applied to computational geometry and multimedia problems. In this paper, we will show how Voronoi diagram can be applied to spatial query processing, and in particular to Reverse Nearest Neighbor (RNN) queries. Spatial and geographical query processing, in general, and RNN in particular, are becoming more important, as online maps are now widely available. In this paper, using the concept of Voronoi diagram, we classify RNN into four types depending on whether the query point and the interest objects are the generator points of the Voronoi Polygon or not. Our approach is based on manipulating Network Voronoi Diagram properties and applying a progressive incremental network expansion for finding the polygon inner network distances required to solve RNN queries. Our experimentation results show that our approaches have good response times in answering RNN queries.     

Membrane transport of long-chain fatty acids: evidence for a facilitated process

In mammalian cells, membrane uptake of long-chain fatty acids is mediated by two separate components; a passive component that is a linear function of the concentration of free fatty acid in the extracellular medium and a saturable component that exhibits the characteristics of a protein-facilitated process. This review summarizes the body of work that has accumulated related to the mechanism of fatty acid transport. Evidence in support of a facilitated uptake process is presented with relation to the different cell types or membrane systems where it was collected. The evidence includes saturation kinetics, competition between different substrates, and sensitivity to a variety of inhibitors. Recent knowledge related to membrane proteins thought to be implicated in the uptake process is reviewed. Factors that may modulate uptake or alter the relative contribution of passive versus facilitated components are briefly discussed. These include the molar ratio of fatty acid to its physiological carrier, plasma albumin and the metabolic or hormonal milieu.     

MgO-Based Epitaxial Magnetic Tunnel Junctions Using Fe-V Electrodes

To examine the influence of the barrier quality in fully epitaxial Fe/MgO/Fe(001) magnetic tunnel junctions (MTJs), we propose to use Fe-V alloys as magnetic electrodes. This leads to a reduced misfit with MgO. We actually observe, by high-resolution electron microscopy (HREM) and local strain measurements, that the misfit dislocations density in the MgO barrier is lower when it is grown on Fe-V(001). This improvement of the crystalline quality of the MgO barrier actually leads to a significant increase of the tunnel magneto-resistance (TMR), despite the loss of spin polarization (SP) in these alloys, which was measured by spin-polarized X-ray photoelectron spectroscopy (SR-XPS).     

Antigenic and molecular characterization of wild type 1 poliovirus causing outbreaks of poliomyelitis in Albania and neighboring countries in 1996

Mass vaccination has led poliomyelitis to become a rare disease in a large part of the world, including Western Europe. However, in the past 20 years wild polioviruses imported from countries where polio is endemic have been responsible for outbreaks in otherwise polio-free European countries. We report on the characterization of poliovirus isolates from a large outbreak of poliomyelitis that occurred in Albania in 1996 and that also spread to the neighboring countries of Yugoslavia and Greece. The epidemics involved 145 subjects, mostly young adults, and caused persisting paralysis in 87 individuals and 16 deaths. The agent responsible for the outbreak was isolated from 74 patients and was identified as wild type 1 poliovirus by both immunological and molecular methods. Sequence analysis of the genome demonstrated the involvement of a single virus strain throughout the epidemics, and genotyping analysis showed 95% homology of the strain with a wild type 1 poliovirus strain isolated in Pakistan in 1995. Neutralization assays with both human sera and monoclonal antibodies were performed to analyze the antigenic structure of the epidemic strain, suggesting its peculiar antigenic characteristics. The presented data underline the current risks of outbreaks due to imported wild poliovirus and emphasize the need to improve vaccination efforts and also the need to implement surveillance in countries free of indigenous wild poliovirus.     

Ultrasound Assessment of Carotid Plaque Echogenicity Response to Statin Therapy: A Systematic Review and Meta-Analysis

Objective: To evaluate in a systematic review and meta-analysis model the effect of statin therapy on carotid plaque echogenicity assessed by ultrasound. Methods: We have systematically searched electronic databases (PubMed, MEDLINE, EMBASE and Cochrane Center Register) up to April, 2015, for studies evaluating the effect of statins on plaque echogenicity. Two researchers independently determined the eligibility of studies evaluating the effect of statin therapy on carotid plaque echogenicity that used ultrasound and grey scale median (GSM) or integrated back scatter (IBS). Results: Nine out of 580 identified studies including 566 patients’ carotid artery data were meta-analyzed for a mean follow up of 7.2 months. A consistent increase in the echogenicity of carotid artery plaques, after statin therapy, was reported. Pooled weighted mean difference % (WMD) on plaque echogenicity after statin therapy was 29% (95% CI 22%–36%), p < 0.001, I² = 92.1%. In a meta-regression analysis using % mean changes of LDL, HDL and hsCRP as moderators, it was shown that the effects of statins on plaque echogenicity were related to changes in hsCRP, but not to LDL and HDL changes from the baseline. The effect of statins on the plaque was progressive; it showed significance after the first month of treatment, and the echogenicity continued to increase in the following six and 12 months. Conclusions: Statin therapy is associated with a favorable increase of carotid plaque echogenicity. This effect seems to be dependent on the period of treatment and hsCRP change from the baseline, independent of changes in LDL and HDL.     

Access and Sharing Contents Through the Social Network: A POMDP Approach

Users interact in the social network by exchanging useful information. The huge amount of traffic generated requires the design of an accurate model for good management. Hence, knowing the consumers' access patterns is of a great interest for content owners. We propose a study of the access and sharing patterns based on the content's popularity. We suppose that popularity is inferred by the observation of the number of views. Our goal is twofold. On the one hand, we aim to help users select the optimal action that allows content owners to decide to change or not the used social network to another to increase their profits and, on the other hand, to assist consumers, according to their area of interest, to decide to access or not a posted content. We establish a threshold structure of the optimal policies based on a trade‐off study between profits (money, access to useful information, etc.) and costs (time spent to edit or consult content, etc.). The experimental results of the proposed analytical model show that both owners and consumers maximize their utility by choosing the best strategies.     

Pressure-Induced Frequency Lineshifts in the nu2 Band of Ammonia: An Experimental Test of the Rydberg-Ritz Principle

The hemolytic lectin, CEL-III, is a Ca2+-dependent, galactose/N-acetylgalactosamine-specific lectin purified from the marine invertebrate, Cucumaria echinata (Holothuroidea). After binding to specific carbohydrates on the erythrocyte surface, CEL-III forms ion-permeable pores by oligomerizing in the membrane, which leads to colloid osmotic rupture of the cells. When incubated with liposomes composed of total lipids from the human erythrocyte membrane, CEL-III efficiently induced the leakage of carboxyfluorescein (CF) trapped in the vesicles, suggesting the presence of its receptor in the membrane lipids. The rate of CF-leakage increased with increasing temperature, although the hemolytic activity of CEL-III had been found to be much higher at lower temperatures (around 10 degrees C). Identification of the receptor for CEL-III was performed by examining the ability of individual lipids from human erythrocytes to induce CF-leakage from DOPC-liposomes. As a result, the most effective receptor was found to be lactosyl ceramide (LacCer), while globoside (Gb4Cer) also showed slight induction of CF-leakage. On the other hand, a binding assay involving CEL-III-horseradish peroxidase conjugate indicated that CEL-III exhibits similar affinity for LacCer and Gb4Cer, suggesting that the structure or length of the carbohydrate portion of sphingoglycolipids is also relevant as to their ability to induce CF-leakage in addition to their affinity. Electron micrographs of CEL-III-treated liposomes revealed that CEL-III induced considerable morphological changes in the vesicles, while a clearly distinguishable oligomeric structure of the protein was not observed.     

Diabetes and Hypertension Consistently Predict the Presence and Extent of Coronary Artery Calcification in Symptomatic Patients: A Systematic Review and Meta-Analysis

Background: The relationship of conventional cardiovascular risk factors (age, gender, ethnicity, diabetes, dyslipidaemia, hypertension, obesity, exercise, and the number of risk factors) to coronary artery calcification (CAC) presence and extent has never before been assessed in a systematic review and meta-analysis. Methods: We included only English language studies that assessed at least three conventional risk factors apart from age, gender, and ethnicity, but excluded studies in which all patients had another confirmed condition such as renal disease. Results: In total, 10 studies, comprising 15,769 patients, were investigated in the systematic review and seven studies, comprising 12,682 patients, were included in the meta-analysis, which demonstrated the importance of diabetes and hypertension as predictors of CAC presence and extent, with age also predicting CAC presence. Male gender, dyslipidaemia, family history of coronary artery disease, obesity, and smoking were overall not predictive of either CAC presence or extent, despite dyslipidaemia being a key risk factor for coronary artery disease (CAD). Conclusion: Diabetes and hypertension consistently predict the presence and extent of CAC in symptomatic patients.