Improved Spectrum Mobility using Virtual Reservation in Collaborative Cognitive Radio Networks

Cognitive radio technology would enable a set of secondary users (SU) to opportunistically use the spectrum licensed to a primary user (PU). On the appearance of this PU on a specific frequency band, any SU occupying this band should free it for PUs. Typically, SUs may collaborate to reduce the impact of cognitive users on the primary network and to improve the performance of the SUs. In this paper, we propose and analyze the performance of virtual reservation in collaborative cognitive networks. Virtual reservation is a novel link maintenance strategy that aims to maximize the throughput of the cognitive network through full spectrum utilization. Our performance evaluation shows significant improvements not only in the SUs blocking and forced termination probabilities but also in the throughput of cognitive users.Comment: 7 pages, 10 figures, IEEE ISCC 201

Housing policy and finance in Egypt: extending the reach of mortgage credit

This thesis attempts to address the need for a clear strategy for the supply side in the Egyptian mortgage market. The thesis focuses for the first time on the issues in relation to the role of the bank and non-bank financial institutions in the creation of an effective and sustainable mortgage market that works better for low- and moderate-income households in Egypt as well as the role of these institutions after the mortgage market has reached a certain stage of development. The key research objectives are as follows: 1) to address why Egyptian housing co-operative societies can be seen as important policy agents to expand the mortgage credit beneficiaries base in Egypt; 2) to evaluate the effectiveness of the Egyptian housing co-operative societies as community based organisations and policy agents; 3) to identify and analyse the various economic, social and political factors influencing this effectiveness; 4) to assess the role of the banking institutions (as contextual stakeholders in the immediate environment of the Egyptian housing co-operative societies) in expanding access to mortgage credit and savings in Egypt; and 5) to identify which institutions constrain most the development of an effective and sustainable level of mortgage credit for low- and moderate-income households. In order to address these issues and objectives, the researcher reviewed the theoretical and empirical issues associated with the assessment of mortgage credit intermediation models to identify their reach and the limit of that reach and, implicitly, to examine what needs to be done to close the gap on what would be a more accessible mortgage market. Further, from 2008 to 2010, the researcher surveyed and interviewed a group of banking, co-operative and government officers in Cairo, Egypt. Questions regarding their attitudes towards housing policy and finance in Egypt were posed, especially in relation to the provision of mortgage credit in Egypt. The thesis found that Egyptian banking institutions, as agents in carrying out housing policies and finance, enabled the housing co-operative societies as stakeholders to form expectations towards the results of the new reforms with the same framework as they had done before. The survey and interviews showed that housing co-operative societies were dissatisfied with the expected results of recent reforms in the Egyptian housing and mortgage markets. It appears that resistance to the reforms was caused by the fact that housing co-operative societies were not interested. But the thesis found that the unfair distributive results associated with mortgage credit allocation were resented most by housing co-operative societies. Thus, the thesis concludes that to extend the reach of mortgage credit, there needs to be a wider strategy to reform the housing and mortgage markets in Egypt that includes strengthening the role of community institutions such as Egyptian housing co-operative societies based on well defined and structured stakeholder framework

Anatomical variations of the hand extensors

This study was performed to investigate the anatomy and variations of the humanextensor tendons of the fingers and their intertendinous connections. Ninetyfive upper limbs of adult cadavers were dissected. The variations in the extensortendons of the fingers, both proximal and distal to the extensor retinaculum, andtheir mode of insertion were observed. Also, the intertendinous connections wereexplored and the obtained data were analysed. The extensor pollicis longus andbrevis tendons were found to be single, doubled or, rarely, absent. Their insertioncould be traced to either the proximal phalanx, or through the extensor expansionto both phalanges, or rarely to the distal phalanx of thumb. The extensor indicishad a single tendon in all specimens. In the majority of specimens, extensor digitorumhad no independent slip to the little finger; it gave off a single tendonto the index, double tendons to the middle finger and triple tendons to the ringfinger. Extensor digiti minimi muscle often had double or triple tendons distal tothe extensor retinaculum. Three types of juncturae tendinum (JT) were identifiedbetween the tendons of extensor digitorum in the 2nd, 3rd and 4th intermetacarpalspaces (IMS) of hands. Types 1 and 2 JT were seen in the three IMS. Type 3 JTwas the most frequently identified of all juncturae and was always absent in the2nd IMS. The percentages of the present data were compared with other researchers’data

Existence and multiplicity for elliptic problems with quadratic growth in the gradient

We show that a class of divergence-form elliptic problems with quadratic growth in the gradient and non-coercive zero order terms are solvable, under essentially optimal hypotheses on the coefficients in the equation. In addition, we prove that the solutions are in general not unique. The case where the zero order term has the opposite sign was already intensively studied and the uniqueness is the rule.Comment: To appear in Comm. PD

Ion beam and discharge characteristics of cold cathode ion source

24-30In this work, some developments in the acceleration system of cold cathode ion source have been constructed to produce broad beam to be used in different industrial applications. An electrostatic probe with electrical circuit is constructed for study the extracted ion beam distribution. Broad beam 25 mm with ion current in the range of 1 mA is extracted from the constructed extraction system. The obtained optimum distance between the extraction grid and acceleration grid is 3 mm. The characteristics are measured to investigate the ion beam current Ib as a function of different parameters (discharge voltage Vd, gas pressure P, magnetic field intensity B and acceleration voltage Vacc). The magnetic field is collimated and intensifies the plasma that enhances the extracted beam current. The obtained cold cathode ion source can be used in different applications like surface etching, surface modification and deposition due to its long life and compactness

Gastrografin in the management of adhesive small bowel obstruction in children: a pilot study

Background/purpose Adhesive small bowel obstruction (ASBO) is a common emergency problem in children with previous abdominal surgery. Management protocols usually start with a conservative approach that may be successful in some cases, whereas in others it will end eventually by laparotomy with its associated morbidity and mortality. Our aim was to assess the role of water-soluble contrast, gastrografin, in the conservative management of ASBO. Patients and methods During the period January 2009 to July 2010, 33 patients with ASBO were presented at the Pediatric Surgery Unit at the Ain Shams University Hospitals. Patients who failed to improve after 48 h of conservative management in the absence of signs of strangulation were subjected to gastrografin administration. Patients were evaluated clinically and radiologically to determine the resolution of the adhesive attack, with estimation of hospital stay time. Results An oral administration of gastrografin successfully completed the conservative management in eight of 12 patients (66.6%), thus avoiding surgery and subsequently reducing hospital stay. Conclusion Gastrografin may have a valuable role in the management of ASBO, whether diagnostic or therapeutic, but a randomized controlled trial is needed to prove its effectiveness in reducing surgical intervention rate and hospital stay time.Keywords: adhesive, bowel obstruction, gastrografi

Ion beam and discharge characteristics of cold cathode ion source

In this work, some developments in the acceleration system of cold cathode ion source have been constructed to produce broad beam to be used in different industrial applications. An electrostatic probe with electrical circuit is constructed for study the extracted ion beam distribution. Broad beam 25 mm with ion current in the range of 1 mA is extracted from the constructed extraction system. The obtained optimum distance between the extraction grid and acceleration grid is 3 mm. The characteristics are measured to investigate the ion beam current Ib as a function of different parameters (discharge voltage Vd, gas pressure P, magnetic field intensity B and acceleration voltage Vacc). The magnetic field is collimated and intensifies the plasma that enhances the extracted beam current. The obtained cold cathode ion source can be used in different applications like surface etching, surface modification and deposition due to its long life and compactness