609 research outputs found
Energy Efficient Scheduling via Partial Shutdown
Motivated by issues of saving energy in data centers we define a collection
of new problems referred to as "machine activation" problems. The central
framework we introduce considers a collection of machines (unrelated or
related) with each machine having an {\em activation cost} of . There
is also a collection of jobs that need to be performed, and is
the processing time of job on machine . We assume that there is an
activation cost budget of -- we would like to {\em select} a subset of
the machines to activate with total cost and {\em find} a schedule
for the jobs on the machines in minimizing the makespan (or any other
metric).
For the general unrelated machine activation problem, our main results are
that if there is a schedule with makespan and activation cost then we
can obtain a schedule with makespan \makespanconstant T and activation cost
\costconstant A, for any . We also consider assignment costs for
jobs as in the generalized assignment problem, and using our framework, provide
algorithms that minimize the machine activation and the assignment cost
simultaneously. In addition, we present a greedy algorithm which only works for
the basic version and yields a makespan of and an activation cost .
For the uniformly related parallel machine scheduling problem, we develop a
polynomial time approximation scheme that outputs a schedule with the property
that the activation cost of the subset of machines is at most and the
makespan is at most for any
GaAs Growth on Sapphire Substrates (C and R Plane) for Integrated Microwave Photonics (IMWP)
The microwave signal processing in the optical domain creates new opportunities for information and communication technology (ICT) and networks by increasing speed, bandwidth, and processing capability. IMWP incorporates the functions of microwave photonics components/subsystems in monolithic or hybrid photonic circuits to meet future needs. Sapphire platforms have the potential to integrate all-in-one, for instance, light source, analog signal processing, light detection, CMOS control circuit, silicon on sapphire to achieve high-performance, low-cost mixed-signal optical links etc. Molecular beam epitaxy (MBE) has been used to grow GaAs on sapphire substrates to integrate optoelectronic devices in the same platform.
The initial stage of GaAs thin film growth has been investigated extensively in both c and r plane sapphire substrates. Direct growth of GaAs on both sapphires results in three-dimensional (3D) islands. In c-plane sapphire, 50% twin volume of GaAs islands, and in r-plane sapphire, two primary domains of GaAs islands are observed. A strong interaction between the growth of GaAs on r-plane sapphire is observed than the growth of GaAs on c-plane sapphire. A thin AlAs nucleation layer improves the wetting of both substrates. After inserting the AlAs nucleation layer, in c- plane sapphire, twin volume is reduced to 16%, and in r-plane sapphire twin is introduced. Further, we investigated the effect of growth temperature, pre-growth sapphire substrate surface treatment, and in-situ annealing on the quality of GaAs epilayer on c-plane sapphire substrates. We have been able to reduce the twin volume to below 2% and an XRD rocking curve linewidth to 223 arcsec in a c-plane sapphire substrate.
To grow high quality GaAs (111)A buffers on an atomically flat sapphire substrate, a two-step growth method has been introduced where, at an early stage, a GaAs layer has been grown at low temperature, followed by a second high-temperature GaAs growth layer. In addition to the two-step process, an AlAs nucleation layer and multiple annealing steps have been employed. Relaxed, smooth surface morphology and high-quality GaAs is achieved with the presence of the LT GaAs layer. A two-dimensional InGaAs quantum well (QW) was epitaxially grown on the 70 nm GaAs buffer and compared with a reference to two-dimensional InGaAs QW grown on GaAs (111)A substrate. Along with X-ray and high-resolution cross-section transmission electron microscopy, comparable QW photoluminescence intensity and linewidth confirmed our growth strategies effectiveness to produce high-quality GaAs on sapphire.
The film thickness was improved up to almost 500 nm by changing the growth parameters such as growth temperature and annealing temperature. We have achieved the room temperature (RT) photoluminescence. The 16 μm microdisk laser was fabricated on GaAs/sapphire system and characterize by micro-PL measurements. The lasing was not successful. The higher surface roughness needs to be optimized to get lasing. We will fabricate GaAs/sapphire QW for electrically pumped laser and realize the photonic chip on the sapphire platform in a long-term goal
Assessment of the Toxic Effect of Hexavalent Chromium on the Hematological Indices in Nile Tilapia, Oreochromis Niloticus
The presence of heavy metals, which are typically released into water bodies as a result of fast industrialization, causes the aquatic environment to become extremely contaminated. Chromium is one of the most common heavy metals in the environment and is used in several types of industries. The effect of sublethal toxicity of hexavalent chromium Cr (VI) on hematological indices of the Nile tilapia, Oreochromis niloticus has been analyzed following exposure of concentration 9.349 mg/L and 18.698 mg/L (10% & 20% of LC50 value) of potassium dichromate (K2Cr2O7) as hexavalent chromium for 7, 15, 30 days. Hematological parameters are the most important indicators of fish health status. The aim of this study was to determine the effect of Cr (VI) toxicity on hematological parameters in O. niloticus. The results show that hemoglobin percentage (Hb%), red blood cell (RBC), mean corpuscular volume (MCV), and platelet count level were significantly (P > 0.05) decreased and the total count of white blood cell (WBC) was significantly (P > 0.05) increased with increasing time of exposure at a concentration of 9.349 mg/L of K2Cr2O7 in the test groups compared to the control group. At the concentration of 18.69 mg/L, Hb%, RBC, MCV, mean corpuscular hemoglobin concentration (MCHC), and platelet count level were significantly (P > 0.05) decreased and the total count of WBC and erythrocyte sedimentation rate (ESR) value were significantly (P > 0.05) increased with the increasing time of exposure in the test groups compared to the control group. To study the R2 value of the linear regression equation, we found that the trend of the chronic toxic effect of hexavalent chromium at 60 and 90 days of both the sublethal concentrations 9.349 mg/L and 18.69 mg/L of K2Cr2O7, where the value of Hb, RBC, packed volume cell (PCV), MCV are found to drastically decreased and the value ESR and WBC are found to drastically increased in the experimental groups compared to the control group. The investigation recommended that the presence of hexavalent chromium in the aquatic medium has a strong impact on the hematological indices in O. niloticus
FIRST REPORT ON FIBRINOLYTIC AND THROMBOLYTIC ACTIVITY OF EUTYPHOEUS GAMMIEI AN EARTHWORM SPECIES COLLECTED FROM TRIPURA, NORTHEAST INDIA
Objective: The present investigation for the first time evaluated the in vitro fibrinolytic and thrombolytic activities of crude extracts from Eutyphoeus gammiei, native, large size earthworm of Tripura, Northeast, India. The present study was designed to evaluate the therapeutic use of the organism E. gammiei as a source of fibrinolytic and thrombolytic agent(s).Methods: The fibrinolytic activity was studied using by fibrin plate and zymography assays. Thrombolytic assay was carried out according to Prasad et al. (2006) using whole blood.Results: The results obtained clearly indicated E. gammiei as a potential source of fibrinolytic and thrombolytic agents. Both in fibrin plate assay and thrombolytic assay with whole blood, E. gammiei crude homogenate showed similar and close results in respect to that of streptokinase. Fibrin zymography also showed antifibrinolytic activity with producing clear bands. Dose and time dependency also is evident from the results.Conclusion: The results of the present study conclude that the studied earthworm species E. gammiei possessed profound fibrinolytic and thrombolytic activity on human blood and E. gammiei might prove to be useful alternative source for the development of new drugs for treatments involving blood coagulation and fibrinolysis
Vulnerable Path Determination in mobile ad-hoc networks using Markov Model
Security threats are of major concern in information sensitive ad-hoc networks like emergency military communication networks. We propose a Proactive Information Security Management System (PISMS) framework with vulnerable path determination module (VPDM) for such mobile ad-hoc networks. The chief security officer can use it to identify the most vulnerable paths, so that they can be patched using suitable security technologies before the hackers actually attack and compromise them. Our PISMS computes (i) the probability of transitioning from each node to its adjacent neighbors, using two key indicators (angle and distance); (ii) number of steps required to reach a pre-determined destination from different sources using Markov model. The path that requires minimum number of steps to reach a destination is the most vulnerable path. This mechanism of identifying vulnerable path is incorporated as an integral part of the Information systems acquisition, development and maintenance (ISADM) module of ISMS framework ISO27001
Study protocol and design for the assessment of paediatric pneumonia from X-ray images using deep learning
Introduction In low-income and middle-income countries, pneumonia remains the leading cause of illness and death in children<5 years. The recommended tool for diagnosing paediatric pneumonia is the interpretation of chest X-ray images, which is difficult to standardise and requires trained clinicians/radiologists. Current automated computational tools have primarily focused on assessing adult pneumonia and were trained on images evaluated by a single specialist. We aim to provide a computational tool using a deep-learning approach to diagnose paediatric pneumonia using X-ray images assessed by multiple specialists trained by the WHO expert X-ray image reading panel.Methods and analysis Approximately 10 000 paediatric chest X-ray images are currently being collected from an ongoing WHO-supported surveillance study in Bangladesh. Each image will be read by two trained clinicians/radiologists for the presence or absence of primary endpoint pneumonia (PEP) in each lung, as defined by the WHO. Images whose PEP labels are discordant in either lung will be reviewed by a third specialist and the final assignment will be made using a majority vote. Convolutional neural networks will be used for lung segmentation to align and scale the images to a reference, and for interpretation of the images for the presence of PEP. The model will be evaluated against an independently collected and labelled set of images from the WHO. The study outcome will be an automated method for the interpretation of chest radiographs for diagnosing paediatric pneumonia.Ethics and dissemination All study protocols were approved by the Ethical Review Committees of the Bangladesh Institute of Child Health, Bangladesh. The study sponsor deemed it unnecessary to attain ethical approval from the Academic and Clinical Central Office for Research and Development of University of Edinburgh, UK. The study uses existing X-ray images from an ongoing WHO-coordinated surveillance. All findings will be published in an open-access journal. All X-ray labels and statistical code will be made openly available. The model and images will be made available on request
- …