Efficient Certification Path Discovery for MANET

A Mobile Ad Hoc Network (MANET) is characterized by the lack of any infrastructure, absence of any kind of centralized administration, frequent mobility of nodes, network partitioning, and wireless connections. These properties make traditional wireline security solutions not straightforwardly applicable in MANETs, and of course, constitute the establishment of a Public Key Infrastructure (PKI) in such networks a cumbersome task. After surveying related work, we propose a novel public key management scheme using the well-known web-of-trust or trust graph model. Our scheme is based on a binary tree formation of the network's nodes. The binary tree structure is proved very effective for building certificate chains between communicating nodes that are multihops away and the cumbersome problem of certificate chain discovery is avoided. We compare our scheme with related work and show that it presents several advantages, especially when a fair balancing between security and performance is desirable. Simulations of the proposed scheme under different scenarios demonstrate that it is effective in terms of tree formation, join and leave occurrences, and certificate chain establishment

Your face scares me: Effects of Perceptual load and Social Anxiety on processing of threatening and neutral faces

Social Anxiety Disorder is among the most widely studied psychiatric conditions. However, the role of attentional and emotional processes in the maintenance of the condition is still not well-established. This study addressed the impact of individual differences in Social Anxiety, by examining the effects of perceptual load and stimulus valence when processing faces vs objects, here used as distractors, within a letter-search task. In addition to RT and accuracy on the letter search task, heart rate, and skin conductance during the task and participants' self-report emotional evaluation were assessed to help interpret performance effects. Results suggest that distractor stimuli that are either threatening or faces impair performance of high SA participants. Results demonstrate a hypervigilance for threatening faces in SA but indicate that this happens primarily when cognitive resources are available, that is, under low perceptual load

Chest Wall Hydatidosis as the Unique Location of the Disease: Case Report and Review of the Literature

The chest wall is a rare location of secondary hydatidosis, but secondary hydatidosis may occur from the rupture of a lung cyst, from a liver cyst invading the diaphragm into the pleural cavity, following previous thoracic surgery for hydatidosis, or by hematogenous spread. This report describes a case of chest wall hydatidosis, which was the primary disease site in the patient, who had no previous history or current disease (hydatidosis) at other sites. The cyst invaded and partially destroyed the 9th and 10th ribs and the 10th thoracic vertebra, and protruded outside the pleural cavity through the 9th intercostal space. Preoperative albendazole administration for 10 days, surgical resection of the disease through a posterolateral thoracotomy incision, and postoperative albendazole treatment resulted in a cure with no evidence of local recurrence or disease at other sites in four years of follow-up

Efficient Certification Path Discovery for MANET

A Mobile Ad Hoc Network (MANET) is characterized by the lack of any infrastructure, absence of any kind of centralized administration, frequent mobility of nodes, network partitioning, and wireless connections. These properties make traditional wireline security solutions not straightforwardly applicable in MANETs, and of course, constitute the establishment of a Public Key Infrastructure (PKI) in such networks a cumbersome task. After surveying related work, we propose a novel public key management scheme using the well-known web-of-trust or trust graph model. Our scheme is based on a binary tree formation of the network's nodes. The binary tree structure is proved very effective for building certificate chains between communicating nodes that are multihops away and the cumbersome problem of certificate chain discovery is avoided. We compare our scheme with related work and show that it presents several advantages, especially when a fair balancing between security and performance is desirable. Simulations of the proposed scheme under different scenarios demonstrate that it is effective in terms of tree formation, join and leave occurrences, and certificate chain establishment.</p

Pulmonary echinococcosis presenting as a pulmonary mass with fever and haemoptysis; a case report

SUMMARY. Hydatidosis, which is caused by larval stage of Echinococcus granulosus, is the most frequently encountered type of anthropozoonosis, and it has been known for centuries. Due to the traditional close association between sheep, dogs and humans, Echinococcus granulosus is endemic in many parts of the world and particularly the Mediterranean countries. The case is reported of a 68 year-old man, a farmer and non smoker, who presented with a 32 day history of haemoptysis and fever. On chest X-ray a mass was observed at the hilum of the right lung. He underwent full clinical, laboratory, and endoscopic evaluation, which was unrevealing. During right thoracotomy a right lower lobectomy was performed that included the mass. Frozen section of the mass was negative for malignancy and the final histopathological examination established the diagnosis of a ruptured pulmonary echinococcus cyst with abscess formation. The postoperative course was uneventful and the patient was discharged from hospital on the ninth postoperative day being treated with albendazole per os. Pulmonary echinococcosis should be included in the differential diagnosis of a lung mass in patients presenting with haemoptysis, especially if there are domestic animals in their environment. Pneumon 2010, 23(2):176-183