Security aspects in voice over IP systems

Security has become a major concern with the rapid growth of interest in the internet. This project deals with the security aspects of VoIP systems. Various supporting protocols and technologies are considered to provide solutions to the security problems. This project stresses on the underlying VoIP protocols like Session Initiation Protocol (SIP), Secure Real-time Transport Procotol (SRTP), H.323 and Media Gateway Control Protocol (MGCP). The project further discusses the Network Address Translation (NAT) devices and firewalls that perform NAT. A firewall provides a point of defense between two networks. This project considers issues regarding the firewalls and the problems faced in using firewalls for VoIP; it further discusses the solutions about how firewalls can be used in a more secured way and how they provide security

Empirical analysis of BWT-based lossless image compression

The Burrows-Wheeler Transformation (BWT) is a text transformation algorithm originally designed to improve the coherence in text data. This coherence can be exploited by compression algorithms such as run-length encoding or arithmetic coding. However, there is still a debate on its performance on images. Motivated by a theoretical analysis of the performance of BWT and MTF, we perform a detailed empirical study on the role of MTF in compressing images with the BWT. This research studies the compression performance of BWT on digital images using different predictors and context partitions. The major interest of the research is in finding efficient ways to make BWT suitable for lossless image compression.;This research studied three different approaches to improve the compression of image data by BWT. First, the idea of preprocessing the image data before sending it to the BWT compression scheme is studied by using different mapping and prediction schemes. Second, different variations of MTF were investigated to see which one works best for Image compression with BWT. Third, the concept of context partitioning for BWT output before it is forwarded to the next stage in the compression scheme.;For lossless image compression, this thesis proposes the removal of the MTF stage from the BWT compression pipeline and the usage of context partitioning method. The compression performance is further improved by using MED predictor on the image data along with the 8-bit mapping of the prediction residuals before it is processed by BWT.;This thesis proposes two schemes for BWT-based image coding, namely BLIC and BLICx, the later being based on the context-ordering property of the BWT. Our methods outperformed other text compression algorithms such as PPM, GZIP, direct BWT, and WinZip in compressing images. Final results showed that our methods performed better than the state of the art lossless image compression algorithms, such as JPEG-LS, JPEG2000, CALIC, EDP and PPAM on the natural images

Relationship of trabecular and cortical bone to circulating total homocysteine and C-reactive protein in postmenopausal women

Homocysteine (Hcy) and C-reactive protein (CRP) are established risk factors for atherosclerotic cardiovascular disease and are emerging as novel risk factors for osteoporosis. The primary purpose of this study was to determine whether total Hcy and CRP concentrations are associated with trabecular and/or cortical bone mineral content (BMC) or bone mineral density (BMD) in postmenopausal women. The secondary objective was to determine the body composition and nutritional status indices (dietary and circulating) and key biologic factors related to total Hcy and CRP. The tertiary purpose of this study was to examine changes in total Hcy and CRP over one year. We enrolled healthy postmenopausal women (N=242) as part of a randomized, double-blind, placebo-controlled multi-center clinical trial designed to examine the effect of two doses of soy isoflavones on bone loss over three years in early postmenopausal women. This study assessed volumetric BMD at the distal tibia and femur (1/3 site) using peripheral quantitative computed tomography (pQCT) in a subset of women (N=184 for distal tibia; N=237 for 1/3 femur site). Total Hcy and CRP did not contribute to the variability in trabecular BMC of the distal tibia or cortical BMC of the 1/3 femur site using pQCT. Approximately 22% of the variability in trabecular BMC was accounted for by weight, hemoglobin, serum uric acid, and blood glucose. Study site, weight, and age accounted for about 14% of the variability in cortical BMC. The overall variability (19%; p[less than or equal to]0.0001) in total Hcy was accounted for by serum vitamin B₁₂ and creatinine; the overall variability (28%; p[less than or equal to]0.0001) in CRP was accounted for by serum iron, overall percent body fat, serum uric acid, triglycerides, and white blood cell count. Total Hcy and CRP increased, while serum vitamin B₁₂, serum folate, and intracellular folate decreased over a one year period. Total Hcy and CRP were not related to trabecular or cortical bone, but this may be because these women were healthy and non-osteoporotic. Since hemoglobin was a significant contributor to trabecular BMC, while iron was a significant contributor to CRP, it is possible that inflammation may mediate the relationship between iron and trabecular BMC

Synthesis, characterization and biological studies of carboranyl-porphyrin bioconjugates for treatment of brain tumors

Chapter 1 gives a brief introduction to brain tumors, approaches to deliver drug across the blood brain barrier (BBB), boron neutron capture therapy (BNCT) for brain tumors, application of carboranyl derivatives in attempt to treat brain tumors using BNCT. Chapter 2 involves synthesis, characterization and toxicity studies (In vitro and In vivo) of high boron containing pegylated cobaltabisdicarbollide porphyrin for treatment of brain tumors using BNCT. To improve the selectivity towards brain tumors we attempted conjugate several peptides to this non-toxic pegylated cobaltabiscabollide porphyrin. In vivo studies were conducted in collaboration with Dr. David G. Baker at LSU veterinary Medicine. Chapter 3 describes the synthesis, characterization and In vitro studies of carboranyl-porphyrin polyamine conjugates and compared their biological behavior with pegylated carboranyl-porphyrin conjugate, which was also synthesized. The biological results show that the polyamine conjugates had a better cellular uptake and BBB permeability compared to pegylated carboranyl-porphyrin. These results also suggest that polyamine conjugates can be promising BNCT agents. Chapter 4 describes the synthesis, characterization and In vitro studies of carboranyl-porphyrin glucose and polyethylene glycol peptide conjugates. Using the pegylated carboranyl-porphyrin conjugate from chapter 3 we could conjugate the peptides, which are interest of study. In vitro studies on some of the peptide conjugates are currently undergoing

Burnout: An Ethnographic Study of Occupational Stress among Mid-Career IT Professionals in Hyderabad, India

This dissertation focuses on the production of burnout among mid-career IT professionals in the city of Hyderabad, India. My analysis is oriented by two main questions: What is said to produce to burnout among IT workers? Why do IT workers continue to work under conditions that they experience as being extremely stressful? Drawing on in-depth ethnographic interviews with IT workers in Hyderabad, participant observation, and analysis of primary and secondary literature, I argue that burnout among IT workers is produced at the intersection of significant political-economic and cultural shifts. These include, for example, the altered nature of work in the new economy, the blurring between personal and professional space/time, and the cultural privileging of IT-based employment that effectively locks individuals into IT work with seemingly no other options. Employment in the Information Technology (IT) industry has come to symbolize the promise of securing middle-class status and associated livelihoods in post-liberalization India. As a significant body of scholarship demonstrates, this promise has resulted in deep cultural, educational, institutional, and political-economic reorientations in order to facilitate the growth of the IT industry in India. These reorientations, however, have also produced an experience of high stress -- often referred to as burnout in popular discourse -- among some IT professionals. While the making of the new Indian middle class in relation to IT-based work has been investigated at length in scholarly literature, the associated production of occupational stress, i.e. burnout, has received scant attention. My research aims to address this gap. Overall, it contributes to furthering empirical and theoretical understandings of IT-based work in India under contemporary conditions of globalisation

Consumption of sugar sweetened beverages, artificially sweetened beverages, and fruit juice and incidence of type 2 diabetes: systematic review, meta-analysis, and estimation of population attributable fraction.

OBJECTIVES: To examine the prospective associations between consumption of sugar sweetened beverages, artificially sweetened beverages, and fruit juice with type 2 diabetes before and after adjustment for adiposity, and to estimate the population attributable fraction for type 2 diabetes from consumption of sugar sweetened beverages in the United States and United Kingdom. DESIGN: Systematic review and meta-analysis. DATA SOURCES AND ELIGIBILITY: PubMed, Embase, Ovid, and Web of Knowledge for prospective studies of adults without diabetes, published until February 2014. The population attributable fraction was estimated in national surveys in the USA, 2009-10 (n=4729 representing 189.1 million adults without diabetes) and the UK, 2008-12 (n=1932 representing 44.7 million). SYNTHESIS METHODS: Random effects meta-analysis and survey analysis for population attributable fraction associated with consumption of sugar sweetened beverages. RESULTS: Prespecified information was extracted from 17 cohorts (38,253 cases/10,126,754 person years). Higher consumption of sugar sweetened beverages was associated with a greater incidence of type 2 diabetes, by 18% per one serving/day (95% confidence interval 9% to 28%, I(2) for heterogeneity=89%) and 13% (6% to 21%, I(2)=79%) before and after adjustment for adiposity; for artificially sweetened beverages, 25% (18% to 33%, I(2)=70%) and 8% (2% to 15%, I(2)=64%); and for fruit juice, 5% (-1% to 11%, I(2)=58%) and 7% (1% to 14%, I(2)=51%). Potential sources of heterogeneity or bias were not evident for sugar sweetened beverages. For artificially sweetened beverages, publication bias and residual confounding were indicated. For fruit juice the finding was non-significant in studies ascertaining type 2 diabetes objectively (P for heterogeneity=0.008). Under specified assumptions for population attributable fraction, of 20.9 million events of type 2 diabetes predicted to occur over 10 years in the USA (absolute event rate 11.0%), 1.8 million would be attributable to consumption of sugar sweetened beverages (population attributable fraction 8.7%, 95% confidence interval 3.9% to 12.9%); and of 2.6 million events in the UK (absolute event rate 5.8%), 79,000 would be attributable to consumption of sugar sweetened beverages (population attributable fraction 3.6%, 1.7% to 5.6%). CONCLUSIONS: Habitual consumption of sugar sweetened beverages was associated with a greater incidence of type 2 diabetes, independently of adiposity. Although artificially sweetened beverages and fruit juice also showed positive associations with incidence of type 2 diabetes, the findings were likely to involve bias. None the less, both artificially sweetened beverages and fruit juice were unlikely to be healthy alternatives to sugar sweetened beverages for the prevention of type 2 diabetes. Under assumption of causality, consumption of sugar sweetened beverages over years may be related to a substantial number of cases of new onset diabetes

Androidal Fat Dominates in Predicting Cardiometabolic Risk in Postmenopausal Women

We hypothesized that soy isoflavones would attenuate the anticipated increase in androidal fat mass in postmenopausal women during the 36-month treatment, and thereby favorably modify the circulating cardiometabolic risk factors: triacylglycerol, LDL-C, HDL-C, glucose, insulin, uric acid, C-reactive protein, fibrinogen, and homocysteine. We collected data on 224 healthy postmenopausal women at risk for osteoporosis (45.8–65 y, median BMI 24.5) who consumed placebo or soy isoflavones (80 or 120 mg/d) for 36 months and used longitudinal analysis to examine the contribution of isoflavone treatment, androidal fat mass, other biologic factors, and dietary quality to cardiometabolic outcomes. Except for homocysteine, each cardiometabolic outcome model was significant (overall P-values from ≤.0001 to .0028). Androidal fat mass was typically the strongest covariate in each model. Isoflavone treatment did not influence any of the outcomes. Thus, androidal fat mass, but not isoflavonetreatment, is likely to alter the cardiometabolic profile in healthy postmenopausal women

There's an App for That:Development of an Application to Operationalize the Global Diet Quality Score

BACKGROUND: The global diet quality score (GDQS) is a simple, standardized metric appropriate for population-based measurement of diet quality globally.OBJECTIVES: We aimed to operationalize data collection by modifying the quantity of consumption cutoffs originally developed for the GDQS food groups and to statistically evaluate the performance of the operationalized GDQS relative to the original GDQS against nutrient adequacy and noncommunicable disease (NCD)-related outcomes.METHODS: The GDQS application uses a 24-h open-recall to collect a full list of all foods consumed during the previous day or night, and automatically classifies them into corresponding GDQS food group. Respondents use a set of 10 cubes in a range of predetermined sizes to determine if the quantity consumed per GDQS food group was below, or equal to or above food group-specific cutoffs established in grams. Because there is only a total of 10 cubes but as many as 54 cutoffs for the GDQS food groups, the operationalized cutoffs differ slightly from the original GDQS cutoffs.RESULTS: A secondary analysis using 5 cross-sectional datasets comparing the GDQS with the original and operationalized cutoffs showed that the operationalized GDQS remained strongly correlated with nutrient adequacy and was equally sensitive to anthropometric and other clinical measures of NCD risk. In a secondary analysis of a longitudinal cohort study of Mexican teachers, there were no differences between the 2 modalities with the beta coefficients per 1 SD change in the original and operationalized GDQS scores being nearly identical for weight gain (-0.37 and -0.36, respectively, P &lt; 0.001 for linear trend for both models) and of the same clinical order of magnitude for waist circumference (-0.52 and -0.44, respectively, P &lt; 0.001 for linear trend for both models).CONCLUSION: The operationalized GDQS cutoffs did not change the performance of the GDQS and therefore are recommended for use to collect GDQS data in the future.</p