A key distribution scheme for mobile underwater wireless sensor networks

Wireless Sensor Networks consist of small battery-limited devices called sensor nodes. They are used for collecting data from surrounding environment and relay them via wireless communication. One of the recent application areas is underwater sensing. Communication in Underwater Wireless Sensor Networks (UWSN) is different from airborne communication. Radio frequencies cannot be used for UWSN. Instead acoustic waves, which cause extra challenges, are used in UWSN. When UWSNs are deployed in hostile environment, nodes can be captured by an adversary. In order to secure UWSNs, firstly key distribution problem must be addressed. Moreover, UWSNs are inherently mobile since the nodes may be drifted in the sea. In this thesis, we propose a key distribution model which is applied for two group mobility models, namely (i) nomadic mobility model and (ii) meandering current mobility model. Our nomadic mobility based key distribution scheme works in three dimensions. However, this scheme is suitable only for small coastal areas. On the other hand, our meandering mobility based key distribution model is a two dimensional one and spans several kilometers in the open sea. In both schemes, a hierarchical structure is used. Secure and resilient group communication is handled via well-known Blom's key distribution scheme. We analyzed the performance of the proposed schemes using simulations. Our results show that secure connectivity of both schemes is generally high. Of course, mobility causes some temporary decreases in the connectivity, but our schemes help to heal the connectivity performance in time. Moreover, our schemes show good resiliency performance such that capture of some nodes by an adversary only causes very small amount of links between uncaptured nodes to be compromised

A highly resilient and zone-based key predistribution protocol for multiphase wireless sensor networks

Pairwise key distribution among the sensor nodes is an essential problem for providing security in Wireless Sensor Networks (WSNs). The common approach for this problem is random key predistribution, which suffers from resiliency issues in case of node captures by adversaries. In the literature, the resiliency problem is addressed by zone-based deployment models that use prior deployment knowledge. Another remedy in the literature, which is for multiphase WSNs, aims to provide self-healing property via periodic deployments of sensor nodes with fresh keys over the sensor field. However, to the best of our knowledge, these two approaches have never been combined before in the literature. In this paper, we propose a zone-based key predistribution approach for multiphase WSNs. Our approach combines the best parts of these approaches and provides self-healing property with up to 9-fold more resiliency as compared to an existing scheme. Moreover, our scheme ensures almost 100% secure connectivity, which means a sensor node shares at least one key with almost all of its neighbors

An Approach for Classifying Program Failures

Abstract—In this work, we leverage hardware performance counters-collected data to automatically group program failures that stem from closely related causes into clusters, which can in turn help developers prioritize failures as well as diagnose their causes. Hardware counters have been used for performance analysis of software systems in the past. By contrast, in this paper they are used as abstraction mechanisms for program executions. The results of our feasibility studies conducted on two widely-used applications suggest that hardware counters-collected data can be used to reliably classify failures. Keywords-failure classification; debugging aids; hardware performance counters. I

Protective effect of melatonin on blood-brain barrier damage caused by Endotoxemia

Objective: Endotoxins, products of Gram-negative bacteria, are the primary cause of blood-brain barrier (BBB) damage. In the present study, we aimed to investigate the possible neuroprotection mechanisms of melatonin on BBB damage induced by endotoxemia. Methods: Adult, female Sprague-Dawley rats (n = 42) were separated into four random groups as a control group and three treatment groups. Lipopolysaccharide (7,5 mg/kg/day) was administrated for a single dose to generate a 24-hour sepsis model on rats. Melatonin (10 mg/kg/day) was treated a week before sepsis. Afterward, the dissected brain tissues were examined by histopathological, biochemical, and molecular analyses. Results: LPS caused weight loss in the groups. As a result, degenerated neurons with cytoplasmic vacuoles and irregular pyknotic nuclei, pale stained necrotic neurons, and vascular congestion were observed in LPS-exposed rats. However, MEL decreased the number of degenerated neurons in treated groups. MEL treatment increased ZO1 and Occludin immunoreactivity while decreasing TLR4 in brain tissues. MEL effect on protein expression was recorded for ZO1 increase and TLR4 decrease in brain tissue compared to LPS groups. MEL also decreased MDA levels in brain tissue. Conclusions: MEL recovered the degenerative damage of sepsis by contributing to blood-brain barrier integrity, and by decreasing inflammation, thus the neuroprotective effects of MEL might provide an experimental basis for clinical applications

Thoracic Primitive Neuroectodermal Tumor: An Unusual Case and Literature Review

We describe herein a rare case of a primary primitive neuroectodermal tumor (PNET) in the mediastinum of a 75-year-old man. Grossly, the tumor was located in the left upper anterior mediastinum. Transcutaneous fine-needle biopsy (TCNB) revealed small round-cell proliferation. The expression immunohistochemical analysis was confirmed the diagnosis of PNET. He was successfully treated with chemotherapy and is alive with no sign of recurrence for 17 months after the diagnosis

Evaluation of Childhood Obesity, Prevalence, and Related Factors in Istanbul

AIM: Childhood obesity has become a global public health crisis. This study aims to determine the prevalence of obesity and related factors in primary school students in Istanbul. METHODS: This research was conducted between May 2015 and January 2018. A school was selected from each of the districts of Istanbul and research was conducted in 39 primary schools. The study was conducted with a total of 5620 students aged 8-12. The students' descriptive characteristics, eating habits, and activity levels were questioned using the Student Information Form. Subsequently, anthropometric measurements (height-weight) were performed for body mass index assessment. RESULTS: The prevalence of childhood obesity was found to be 15.7%. This rate was 14.1% for female students and 17.3% for male students. Body mass index of students was related to durations of time spent on watching TV (r = .064, p < .05) and computer (r = .037, p < .05). In addition, the body mass index was differentiated by gender (p = .004); male students had a higher body mass index compared to female students, and body mass index was higher in those who skipped main meals (p = .001) and those who did not eat regular breakfast (p = .001). CONCLUSION: The prevalence of obesity in children was found to be quite high. It may easily be stated that obesity prevalence is rapidly increasing in Turkey; therefore, it should be done through regular screening programs, and preventive interventions should be planned

INCREASED ARTERIAL STIFFNESS MEASURED BY CAROTID FEMORAL (AORTIC) PULSE WAVE VELOCITY IN PATIENTS WITH INACTIVE BEHCET'S DISEASE

Introduction Behcet's disease (BD) is a chronic, multisystemic disease characterised by vascular involvement. Acute and chronic inflammatory processes associated with BD may cause endothelial dysfunction, which can then lead to a subsequent increase of arterial stiffness and altered pressure wave reflections. The aim of this study was to evaluate the pulse wave velocity (PWV) measurements in patients with inactive BD and control subjects