Transaction processing in real-time database systems

Scheduling transactions in a real-time database requires an integrated approach in which the schedule does not only guarantee execution before the deadline, but also maintains data consistency. The problem has been studied under a common framework which considers both concurrency control issues and the real-time constraints in centralized and distributed transaction processing. A real-time transaction processing model has been defined for a centralized system. The proposed protocols use a unified approach to maximize concurrency while meeting real-time constraints at the same time. In order to test the behavior of the model and the proposed protocols, a real-time transaction processing testbed has been developed using discrete event simulation techniques. The results indicate that different protocols work better under different load scenarios and that the overall performance can be significantly enhanced by modifying the underlying system configuration. Among other system and transaction parameters, the effect of data partitioning, buffer management, preemption, disk contention, locking mode and multiprocessing has been studied;For the distributed environment, new concepts of real-time nested transactions and priority propagation have been proposed. Real-time nested transactions incorporate the deadline requirements in the hierarchical structure of nested transactions. Priority propagation addresses the issues related to transaction aborts in real-time nested transaction processing. The notion of priority ceiling has been used to avoid the priority inversion problem. The proposed protocols exhibit freedom from deadlock and have tightly bounded waiting period. Both of these properties make them very suitable for distributed real-time transaction processing environment

Defining reference area for prediction of aerodynamic coefficients of a biologically inspired hybrid buoyant vehicle

Geometric and volumetric quantities are usually used to define the reference area for the prediction of aerodynamic coefficients of various aquatic mammals, airships and unmanned vehicle. However, reference area does not have a unique definition, especially for a hybrid buoyant aerial vehicle having hybrid lifting hull which resembles a Steller sea lion. The term square cube root of volume is traditionally used as reference area to nondimensionalize the aerodynamic forces for conventional as well as unconventional airships. Published experimental data are usually available for complete configuration at low speed and in nondimensionalized form. So, a generic model of an aircraft's fuselage was first tested in a wind tunnel as a test case to first determine the lift force and then the influence of different choices of reference area on the lift. A hybrid lifting hull was numerically simulated for the prediction of lift as well as drag coefficients and their ratio. It was found that the volumetric term has undefined correlation with aerodynamic forces in both cases. Changes in aerodynamic coefficients are not prominent when using the wetted area as the reference area. Based on the predicted trends of aerodynamic coefficients and a deep literature survey, the projected planform area is proposed as the best option for reference area of a Steller sea lion as well as for hybrid lifting hull of a hybrid buoyant vehicle

Perception Survey of Civil Servants: A Preliminary Report

Despite various attempts at reforming the civil services the common perception seems to be that the system essentially remains similar to that inherited from the colonial past. Worse still, little is known about the perceptions of civil servants on various issues in civil service reforms. Against this backdrop, the Pakistan Institute of Development Economics conducted a perception survey of civil servants seeking their views on recruitment, training, performance evaluation, job satisfaction, and relationship with the private sector. This preliminary report highlights the key findings of the survey. Section 2 sets out the survey methodology. Sections 3 to 7 respectively highlight the survey findings with respect to recruitment, postings and training, performance evaluation, job satisfaction, bureaucracy, private sector, and institutions and reforms

Reirradiation to the abdomen for gastrointestinal malignancies

<p>Abstract</p> <p>Background</p> <p>Reirradiation to the abdomen could potentially play a role in palliation of symptoms or local control in patients with gastrointestinal malignancies. Our goal was to retrospectively determine rates of toxicity, freedom from local progression and overall survival in gastrointestinal cancer patients treated with reirradiation to the abdomen.</p> <p>Methods</p> <p>Between November 2002 and September 2008, 13 patients with a prior history of abdominal radiotherapy (median dose 45 Gy) were treated with reirradiation for recurrent or metastatic gastrointestinal malignancies. The median interval between the two courses of radiotherapy was 26 months. Patients were treated with a hyperfractionated accelerated regimen, using 1.5 Gy fractions twice daily, with a median dose of 30 Gy (range 24-48 Gy). Concurrent chemotherapy was administered to 8 (62%) patients.</p> <p>Results</p> <p>The 1-year rate of freedom from local progression was 50%, and the median duration of freedom from local progression was 14 months. The 1-year rate of overall survival was 62%, and the median duration of overall survival was 14 months. One patient developed grade 3 acute toxicity (abdominal pain and gastrointestinal bleeding), requiring hospitalization during radiotherapy; subsequently, that patient experienced a grade 4 late toxicity (gastrointestinal bleeding). No other patients developed grade 3-4 acute or late toxicity or required hospitalization during radiotherapy.</p> <p>Conclusion</p> <p>Hyperfractionated accelerated reirradiation to the abdomen was well-tolerated with low rates of acute and late toxicity. Reirradiation could play a role in providing a limited duration of local control in gastrointestinal cancer patients with a history of prior abdominal radiotherapy.</p

Comparison of digital DATCOM and wind tunnel data of a winged hybrid airship’s generic model

Use of low fidelity tools in designing subscale generic wind tunnel models is usually required to get first-hand knowledge about general trends of aerodynamic and stability parameters. Most of such tools are limited to well-defined conventional aircraft configurations. In the present work, aerodynamic and stability characteristics of a winged hybrid airship is explored at low subsonic speed by using Aircraft Digital DATCOM, which is based on semi-empirical methods for preliminary aircraft geometries. Spheroidal ellipsoidal shaped hull of the airship is modeled in DATCOM along with the geometrical details of wing and empennages. The prediction of zero lift drag coefficient, coefficient of lift and pitching moment is the focus of this paper. Except the drag coefficients, trends of analytical results compare well with experimental dat

AEROSTATIC AND AERODYNAMIC MODULES OF A HYBRID BUOYANT AIRCRAFT: AN ANALYTICAL APPROACH

An analytical approach is essential for the estimation of the requirements of aerodynamic and aerostatic lift for a hybrid buoyant aircraft. Such aircrafts have two different modules to balance the weight of aircraft; aerostatic module and aerodynamic module. Both these modules are to be treated separately for estimation of the mass budget of propulsion systems and required power. In the present work, existing relationships of aircraft and airship are reviewed for its further application for these modules. Limitations of such relationships are also disussed and it is precieved that it will provide a strating point for better understanding of design anatomy of such aircraft

Outcomes following stereotactic radiosurgery or whole brain radiation therapy by molecular subtype of metastatic breast cancer

BACKGROUND: This study quantified clinical outcomes by molecular subtype of metastatic breast cancer (BC) following whole brain radiation therapy (WBRT) or stereotactic radiosurgery (SRS). Doing so is important for patient counseling and to assess the potential benefit of combining targeted therapy and brain radiotherapy for certain molecular subtypes in ongoing trials. MATERIALS AND METHODS: The National Cancer Database was queried for BC (invasive ductal carcinoma) cases receiving brain radiotherapy (divided into WBRT and SRS). Statistics included multivariable logistic regression to determine factors associated with SRS delivery, Kaplan-Meier analysis to evaluate overall survival (OS), and Cox proportional hazards modeling. RESULTS: Of 1,112 patients, 186 (16.7%) received SRS and 926 (83.3%) underwent WBRT. Altogether, 410 (36.9%), 195 (17.5%), 162 (14.6%), and 345 (31.0%) were ER+/HER2-, ER+/HER2+, ER–/HER2+, and ER–/HER2–, respectively. In the respective molecular subtypes, the proportion of subjects who underwent SRS was 13.4%, 19.4%, 24.1%, and 15.7%. Respective OS for WBRT patients were 12.9, 22.8, 10.6, and 5.8 months; corresponding figures for the SRS cohort were 28.3, 40.7, 15.0, and 12.9 months (p &lt; 0.05 for both). When comparing OS between treatment different histologic subtypes, patients with ER-/HER2+ and ER–/HER2– disease had worse OS than patients with ER+/HER2– disease, for both patients treated with SRS and for patients treated with WBRT. CONCLUSIONS: Molecular subtype may be a useful prognostic marker to quantify survival following SRS/WBRT for metastatic BC. Patients with HER2-enriched and triple-negative disease had the poorest survival following brain irradiation, lending credence to ongoing studies testing the addition of targeted therapies for these subtypes

The impact of HER2-directed targeted therapy on HER2-positive DCIS of the breast

BACKGROUND: In invasive breast cancer, HER2 is a well-established negative prognostic factor. However, its significance on the prognosis of ductal carcinoma in situ (DCIS) of the breast is unclear. As a result, the impact of HER2-directed therapy on HER2-positive DCIS is unknown and is currently the subject of ongoing clinical trials. In this study, we aim to determine the possible impact of HER2-directed targeted therapy on survival outcomes for HER2-positive DCIS patients. MATERIALS AND METHODS: The National Cancer Data Base (NCDB) was used to retrieve patients with biopsy-proven DCIS diagnosed from 2004–2015. Patients were divided into two groups based on the adjuvant therapy they received: systemic HER2-directed targeted therapy or no systemic therapy. Statistics included multivariable logistic regression to determine factors predictive of receiving systemic therapy, Kaplan-Meier analysis to evaluate overall survival (OS), and Cox proportional hazards modeling to determine variables associated with OS. RESULTS: Altogether, 1927 patients met inclusion criteria; 430 (22.3%) received HER2-directed targeted therapy; 1497 (77.7%) did not. Patients who received HER2-directed targeted therapy had a higher 5-year OS compared to patients that did not (97.7% vs. 95.8%, p = 0.043). This survival benefit remained on multivariable analysis. Factors associated with worse OS on multivariable analysis included Charlson-Deyo Comorbidity Score ≥ 2 and no receipt of hormonal therapy. CONCLUSION: In this large study evaluating HER2-positive DCIS patients, the receipt of HER2-directed targeted therapy was associated with an improvement in OS. The results of currently ongoing clinical trials are needed to confirm this finding

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London