1,144 research outputs found

    Dvali-Gabadadze-Porrati Cosmology in Bianchi I brane

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    The dynamics of Dvali-Gabadadze-Porrati Cosmology (DGP) braneworld with an anisotropic brane is studied. The Friedmann equations and their solutions are obtained for two branches of anisotropic DGP model. The late time behavior in DGP cosmology is examined in the presence of anisotropy which shows that universe enters a self-accelerating phase much later compared to the isotropic case. The acceleration conditions and slow-roll conditions for inflation are obtained

    Clinicopathological Features of Melanocytic Nevi and Their Correlation to Cutaneous Melanoma among Patients Attending King Abdulaziz University Hospital, Jeddah, Saudi Arabia

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    Melanocytic nevi (MN) pose diagnostic difficulty due to their heterogeneous clinical, biological and molecular characteristics. Their recognition is also important because cutaneous melanomas are known to arise in pre-existing MN. Aim: This retrospective study aims to examine the clinical features and histopathological types of MN among patients attending King Abdulaziz University Hospital between January 2000 and December 2017. It also aims to examine the correlation of their number to cutaneous melanoma. Materials and Methods: All biopsy specimen data of pigmented skin lesions were collected through an electronic search of the Anatomic Pathology archives. Age, gender and site distribution and histological features were studiedfor different MN and their relation to cutaneous melanoma if associated. Results: MN were most common in the third decade of life affecting females more than males. The most frequent anatomic location was the head region, 176 (45.3%), with face being most frequent site, 45 (25.5%). Histologically the most common MN wasintradermal type accounting for 217 (56%). Two dysplastic nevi and one congenital nevus was associated with cutaneous melanoma. Conclusion: MN most commonly affected patients in their third decade of life .Females were more affected than males. Histologically most MN were of intradermal type and were rarely associated with cutaneous melanoma

    Impact of reciever on time on the energy saving performance of the watchful sleep mode in a passive optical network

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    Due to increasing bandwidth demands from users, this evolution towards next generation PON (NG-PON) with higher network capacity and split continues. However, increasing split ratio in NGPON also leads to higher power consumption of the PON network due to 60% of the power is being consumed by the optical network units (ONUs). For energy conservation of the ONU, the Watchful Sleep Mode (WSM) has been recently added to the PON standards. This is an integrated mode that combines both the cyclic sleep and doze mode in one operation by periodically turning on the ONU receiver (RX) during the sleep cycle. However, still, the impact of RX on time on the energy saving performance of WSM has not been studied. Therefore, this study presents a performance evaluation of the watchful sleep mode in a 10 GB-capable PON (XG-PON) network with varying RX ON times. The investigation is performed with a dynamic bandwidth assignment scheme and real traffic data from Broadcom CATV head end. A comprehensive review of the power saving techniques for XGPON is also presented. The simulation study results show that higher RX ON time leads to higher energy savings for the ONUs without significantly increasing upstream and downstream delays

    Management and Complications of Arnold Chiari Hydrocephalus at Tertiary Health Care Center

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    Objective: to investigate the role of CT and MRI in diagnosis of Arnold chiari malformation of hydrocephalus and its treatment with VP shunt along with complications. Study Design: Prospective study Place and duration: Department of Neurosurgery, DG Khan Medical College from May 4, 2018 to May 4, 2019. Methodology: Fifty patients of congenital hydrocephalus who were not treated previously were selected. Detailed history about disease and clinical examination of patients was performed. Follow ups were done at neurosurgery OPD. SPSS software for data analysis was used and mean ± SD, frequency and percentages were calculated for variables. P value ≤0.05 was considered as significant. Results: Treatment in case of congenital hydrocephalus as VP shunt, intra-aneurysmal coiling, excision of meningomyelocele with VP shunt and suboccipital craniectomy + upper cervical laminectomy (scucl) were observed as 10%, 6%, 8% and 8% respectively.  Twelve percent of patients were not treated. Conclusion: CT and MRI are the main diagnostic tools for diagnosis of Arnold chiari malformation and VP shunt is the treatment of choice. Among complications of VP shunt infection of shunt and shunt block are the main complications

    An Adaptive Software Fault Tolerant Framework for Ubiquitous Vehicular Technologies

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    Probability for the occurrence of faults increases manifolds when program Lines of Code (LoC) exceeds a few thousand in ubiquitous applications. Faults mitigation in ubiquitous applications, such as those of autonomous Vehicular Technologies (VTs), has not been effective even with the use of formal methods. Faults in such applications require exhaustive testing for a timely fix, that seems infeasible computationally. This emphasizes the imperative role of Software Fault Tolerance (SFT) for autonomous applications. Several SFT techniques have been proposed but failures revealed in VT applications imply that existing SFT techniques need to be fine-tuned. In this paper, current replication-based SFT techniques have been analyzed and classified with respect to their diversity, adjudication, and adaptivity. Essential parameters (such as Reliability, Time, Variance, etc) for adjudication, diversity, and adaptiveness were recorded. The identified parameters were mapped to different techniques (such as AFTRC, SCOP, VFT, etc) for observing their shortcomings. Consequently, a generic framework named ”Diverse Parallel Adjudication for Software Fault Tolerance (DPA-SFT)” has been proposed. DPA-SFT addresses the shortcomings of existing SFT techniques for VTs with the added value of parallel and diverse adjudication. A prototype implementation of the proposed framework has been developed for assessing the viability of DPA-SFT over modules of VT. An empirical comparison of the proposed framework was performed with prevalent techniques (AFTRC, SCOP, VFT, etc). A thorough evaluation suggests that DPA-SFT performs better than contemporary SFT techniques in VTs due to its parallel and diverse adjudication

    Comprehensive Spectral Analysis of Cyg X-1 using RXTE Data

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    We analyse a large number (>500> 500) pointed RXTE observations of Cyg X-1 and model the spectrum of each one. A subset of the observations for which there is simultaneous reliable measure of the hardness ratio by the All Sky Monitor, shows that the sample covers nearly all the spectral shapes of Cyg X-1. The relative strength, width of the Iron line and the reflection parameter are in general correlated with the high energy photon spectral index Γ\Gamma. This is broadly consistent with a geometry where for the hard state (low Γ1.7\Gamma \sim 1.7) there is a hot inner Comptonizing region surrounded by a truncated cold disk. The inner edge of the disk moves inwards as the source becomes softer till finally in the soft state (high Γ>2.2\Gamma > 2.2) the disk fills the inner region and active regions above the disk produce the Comptonized component. However, the reflection parameter shows non-monotonic behaviour near the transition region (Γ2\Gamma \sim 2), suggestive of a more complex geometry or physical state of the reflector. Additionally, the inner disk temperature, during the hard state, is on the average higher than in the soft one, albeit with large scatter. These inconsistencies could be due to limitations in the data and the empirical model used to fit them. The flux of each spectral component is well correlated with Γ\Gamma which shows that unlike some other black hole systems, Cyg X-1 does not show any hysteresis behaviour. In the soft state, the flux of the Comptonized component is always similar to the disk one, which confirms that the ultra-soft state (seen in other brighter black hole systems) is not exhibited by Cyg X-1. The rapid variation of the Compton Amplification factor with Γ\Gamma, naturally explains the absence of spectra with Γ<1.6\Gamma < 1.6, despite a large number having Γ1.65\Gamma \sim 1.65.Comment: 12 pages, 8 figures, accepted for publication in Research in Astronomy and Astrophysics (RAA

    PRODUCTION OF BIOGAS USING FOOD WASTE FROM SRIT HOSTEL

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    Biogas is typically a gas produced by the anaerobic digestion of biodegradable materials. One of the most promising processes for the energetic transformation of waste is the anaerobic digestion of waste to produce biogas. Food waste, which has become one of global concerns because of its massive amount, contains high organic content, which is used by the microbes as nutrients. The present project aims at production of biogas using food waste generated from SRIT hostel. Our institution has three hostels and two messes, cooking food for more than 1000 students, and there is large quantity of food waste generated daily. The option available for the management of this huge waste is animal feed. So this large quantity of food waste generated should be utilized for better purposes. A survey is carried out and it was found that average food waste generated per person is 243g. The set up consists of a digester which is of 2.75 litres capacity and it was filled with 2/3rd of its capacity with mixed food waste and cow dung in 1: 1 proportion. The initial and final characteristics of the feedstock, such as pH, total solids, volatile solids, C/N ratio and COD are analyzed. The volumetric yield of biogas is noted at regular intervals using water displacement method. The cumulative quantity of biogas produced for 31 days is 565 cm3 per 900 gram of feedstock
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