On the Design of Clean-Slate Network Control and Management Plane

We provide a design of clean-slate control and management plane for data networks using the abstraction of 4D architecture, utilizing and extending 4D’s concept of a logically centralized Decision plane that is responsible for managing network-wide resources. In this paper, a scalable protocol and a dynamically adaptable algorithm for assigning Data plane devices to a physically distributed Decision plane are investigated, that enable a network to operate with minimal configuration and human intervention while providing optimal convergence and robustness against failures. Our work is especially relevant in the context of ISPs and large geographically dispersed enterprise networks. We also provide an extensive evaluation of our algorithm using real-world and artificially generated ISP topologies along with an experimental evaluation using ns-2 simulator

A Logically Centralized Approach for Control and Management of Large Computer Networks

Management of large enterprise and Internet Service Provider networks is a complex, error-prone, and costly challenge. It is widely accepted that the key contributors to this complexity are the bundling of control and data forwarding in traditional routers and the use of fully distributed protocols for network control. To address these limitations, the networking research community has been pursuing the vision of simplifying the functional role of a router to its primary task of packet forwarding. This enables centralizing network control at a decision plane where network-wide state can be maintained, and network control can be centrally and consistently enforced. However, scalability and fault-tolerance concerns with physical centralization motivate the need for a more flexible and customizable approach. This dissertation is an attempt at bridging the gap between the extremes of distribution and centralization of network control. We present a logically centralized approach for the design of network decision plane that can be realized by using a set of physically distributed controllers in a network. This approach is aimed at giving network designers the ability to customize the level of control and management centralization according to the scalability, fault-tolerance, and responsiveness requirements of their networks. Our thesis is that logical centralization provides a robust, reliable, and efficient paradigm for management of large networks and we present several contributions to prove this thesis. For network planning, we describe techniques for optimizing the placement of network controllers and provide guidance on the physical design of logically centralized networks. For network operation, algorithms for maintaining dynamic associations between the decision plane and network devices are presented, along with a protocol that allows a set of network controllers to coordinate their decisions, and present a unified interface to the managed network devices. Furthermore, we study the trade-offs in decision plane application design and provide guidance on application state and logic distribution. Finally, we present results of extensive numerical and simulative analysis of the feasibility and performance of our approach. The results show that logical centralization can provide better scalability and fault-tolerance while maintaining performance similarity with traditional distributed approach

Serological and Molecular Investigation of Brucella Species in Dogs in Pakistan

Brucellosis is an important bacterial zoonosis caused by B. abortus and B. melitensis in Pakistan. The status of canine brucellosis caused by B. canis remains obscure. In total, 181 serum samples were collected from stray and working dogs in two different prefectures viz. Faisalabad (n = 87) and Bahawalpur (n = 94). Presence of antibodies against B. canis and B. abortus/B. melitensis was determined using the slow agglutination test (SAT) and ELISA, respectively. Real-time PCR was performed to detect and differentiate Brucella DNA at the species level. In Faisalabad, the serological prevalence was found to be 9.2% (8/87) and 10.3% (9/87) by SAT and ELISA, respectively. Only one of the ELISA positive samples (1.15%) yielded amplification for B. abortus DNA. In Bahawalpur, 63.8% (60/94) samples were found positive by SAT; however, none of the samples was positive by ELISA or by real-time PCR. Location, age (≥1 year) and body condition (weak) were found to be associated with B. canis infection, whereas presence of wounds was found to be associated with B. abortus infection only. These findings point towards a risk of transmission from dog to livestock and humans and vice versa. The study expects to draw the attention of concerned authorities towards infection prevention and animal welfare. This study warrants further epidemiological investigation on brucellosis in pet dogs and their owners. To the best of our knowledge, this is first ever report on B. canis and B. abortus in dogs in Pakistan

An Empirical Study on the Effect of Perceived Usefulness and Ease of Use on Purchase Intention Through Mobile Devices in Pakistan: A Mediating Role of Online Trust

In Pakistan, electronic commerce market is in developing phase, and people are not much familiar with technology. Customers feel fear for providing debit/credit card information to online retailers. This research proposes a theoretical model in which online trust is used as a mediator among perceived ease of use, perceived usefulness and intention to purchase through mobile devices. In this study Smartphone, cellular phones and tablets with internet connection conceived as mobile devices. Data were collected through questionnaire from the students and employees of different universities in Pakistan and analyzed by partial least squares structural equation modeling (PLS-SEM) method. Results suggest that PEOU have an insignificant effect while PU has a positive effect on online trust and purchase intention through mobile devices. Also, online trust does not mediate between PEOU and purchase Intention through mobile devices while it partially mediates between PU and purchase intention through mobile devices. Keywords: Electronic Commerce, Online trust, Intention to purchase through mobile devices, Perceived ease of use, perceived usefulness

Needle stick injuries among health care workers of public sector tertiary care hospitals of Karachi

OBJECTIVE: To estimate the frequency of needle stick injuries (NSI) among health care workers (nurses, student nurses and paramedical staff) in public hospitals of Karachi.STUDY DESIGN: Cross sectional, observational.PLACE AND DURATION OF STUDY: This study was conducted in three public tertiary care hospitals of Karachi, from November 2007 to January 2008.METHODOLOGY: Data was collected by structured interview-based questionnaires in Urdu and English language. Questionnaire was designed to obtain information regarding demography, work experience, hepatitis vaccination status, and occurrence of needle stick injuries with associated factors. Needle stick injury that occurred in the previous month was the defined outcome. Data was entered in Epi Data and analyzed in SPSS version 15.RESULTS: A total of 417 health care workers participated in the study. Mean age of the participants was 24+/-11 years. Estimated proportion of participants with history of at least one time NSI was found in 66%. Around 13% (n=54) had one or more NSI in the previous one month at work and half of them were affected by non-sterile needle. None of them sought medical care. Almost 90% of them were not wearing gloves or taking any other protective measures at the time of injury.CONCLUSION: There can be serious consequences of needle stick injuries in public hospitals as large proportion of injuries involve non-sterile used needles and health care workers do not take appropriate measures of protection

Optimizing the Performance of Data Warehouse by Query Cache Mechanism

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Microsomal Triglyceride Transfer Protein Transfers and Determines Plasma Concentrations of Ceramide and Sphingomyelin but Not Glycosylceramide

Sphingolipids, a large family of bioactive lipids, are implicated in stress responses, differentiation, proliferation, apoptosis, and other physiological processes. Aberrant plasma levels of sphingolipids contribute to metabolic disease, atherosclerosis, and insulin resistance. They are fairly evenly distributed in high density and apoB-containing lipoproteins (B-lps). Mechanisms involved in the transport of sphingolipids to the plasma are unknown. Here, we investigated the role of microsomal triglyceride transfer protein (MTP), required for B-lp assembly and secretion, in sphingolipid transport to the plasma. Abetalipoproteinemia patients with deleterious mutations in MTP and absence of B-lps had significantly lower plasma ceramide and sphingomyelin but normal hexosylceramide, lactosylceramide, and different sphingosines compared with unaffected controls. Furthermore, similar differential effects on plasma sphingolipids were seen in liver- and intestine-specific MTP knock-out (L,I-Mttp(-/-)) mice, suggesting that MTP specifically plays a role in the regulation of plasma ceramide and sphingomyelin. We hypothesized that MTP deficiency may affect either their synthesis or secretion. MTP deficiency had no effect on ceramide and sphingomyelin synthesis but reduced secretion from primary hepatocytes and hepatoma cells. Therefore, MTP is involved in ceramide and sphingomyelin secretion but not in their synthesis. We also found that MTP transferred these lipids between vesicles in vitro. Therefore, we propose that MTP might regulate plasma ceramide and sphingomyelin levels by transferring these lipids to B-lps in the liver and intestine and facilitating their secretion

Isu dan cabaran pekerjaan orang kurang upaya penglihatan di Malaysia

This article aims to explore the employment issues of persons with visual impairment in Malaysia. Based on analysis of the literature reviews, there are two main employment issues faced by persons with visual impairment in Malaysia, namely job opportunity and workplace issues. These issues caused significant dilemmas for persons with visual impairment to work and they give negative implications on their social functioning and career development. In addition, challenges such as impairment effects, age, gender, level of education, vocational training and skills, family, employers’ negative attitudes, transportation, lack of policy enforcement and non-conducive environment in the workplace become the main factors that contribute to the employment issues. Therefore, this article discusses the suggestion for a suitable conceptual framework and methodology that can be used for future research

Human Cryptosporidiosis: An insight into Epidemiology, Modern Diagnostic Tools and Recent Drug Discoveries

Cryptosporidiosis is an emerging food and water borne zoonotic disease, which is caused by genusCryptosporidium. The first Cryptosporidium spp. was isolated from mice in 1907 and gained importance when it was found in an HIV positive patient. It usually causes self-limiting diarrhea in young children and immunocompetent patients. However, it may lead to chronic diarrhea with life threatening condition in immunocompromised patients. Other complications related to this transmittable infection may include respiratory problems, skin rashes and headache. HIV/AIDS patients are highly susceptible host for this parasite. Cryptosporidium parvum and Cryptosporidium hominis are the known pathogenic species, prevalent among humans and they are being transmitted through contaminated food and water. Usually, the diagnosis of Cryptosporidium spp. is dependent on microscopic technique in many countries, which has a low sensitivity and specificity leading to false positive results. However, for a step forward to successful epidemiological studies, advanced techniques (Serological and DNA-based) provide us the better ways of diagnosis with more sensitivity and specificity. Furthermore, no antiparasitic drug has found to be effective againstCryptosporidium spp. except Nitazoxanide which is FDA-approved and effective only when administered along with antiretroviral therapy. In this regard, present review summarizes the various epidemiological studies conducted around the globe along with modern diagnostic tools and the suitable treatment available now a days. This systemized review will help the scientists to better understand all the aspects of cryptosporidiosis at one platform which may help in designing surveillance studies through selection of sensitive diagnostic techniques. The new drugs mentioned in this review may also help to better control this parasite in humans, especially immunocompromised individuals

Genetic Investigation of Consanguineous Pakistani Families Segregating Rare Spinocerebellar Disorders

Spinocerebellar disorders are a vast group of rare neurogenetic conditions, generally characterized by overlapping clinical symptoms including progressive cerebellar ataxia, spastic paraparesis, cognitive deficiencies, skeletal/muscular and ocular abnormalities. The objective of the present study is to identify the underlying genetic causes of the rare spinocerebellar disorders in the Pakistani population. Herein, nine consanguineous families presenting different spinocerebellar phenotypes have been investigated using whole exome sequencing. Sanger sequencing was performed for segregation analysis in all the available individuals of each family. The molecular analysis of these families identified six novel pathogenic/likely pathogenic variants; ZFYVE26: c.1093del, SACS: c.1201C>T, BICD2: c.2156A>T, ALS2: c.2171-3T>G, ALS2: c.3145T>A, and B4GALNT1: c.334_335dup, and three already reported pathogenic variants; FA2H: c.159_176del, APTX: c.689T>G, and SETX: c.5308_5311del. The clinical features of all patients in each family are concurrent with the already reported cases. Hence, the current study expands the mutation spectrum of rare spinocerebellar disorders and implies the usefulness of next-generation sequencing in combination with clinical investigation for better diagnosis of these overlapping phenotypes