1,899 research outputs found
Application of Petrov-Galerkin finite element methodto shallow water waves model: Modified Korteweg-deVries equation
In this article, modi ed Korteweg-de Vries (mKdV) equation is solved
numerically by using lumped Petrov-Galerkin approach, where weight functions are
quadratic and the element shape functions are cubic B-splines. The proposed numerical
scheme is tested by applying four test problems including single solitary wave, interaction of two and three solitary waves, and evolution of solitons with the Gaussian initial condition.
In order to show the performance of the algorithm, the error norms, L2, L1, and a
couple of conserved quantities are computed. For the linear stability analysis of numerical
algorithm, Fourier method is also investigated. As a result, the computed results show that
the presented numerical scheme is a successful numerical technique for solving the mKdV equation. Therefore, the presented method is preferable to some recent numerical methods
A new approach for numerical solution of modified korteweg-de vries equation
In this paper, a lumped Galerkin method is applied with cubic B-spline interpolation functions to find the numerical solution of the modified Korteweg-de Vries
(mKdV) equation. Test problems including motion of single solitary wave, interaction of two solitons, interaction of three solitons, and evolution of solitons are solved to verify
the proposed method by calculating the error norms L2 and L1 and the conserved quantities mass, momentum and energy. Applying the von-Neumann stability analysis, the
proposed method is shown to be unconditionally stable. Consequently, the obtained results are found to be harmony with the some recent result
Detecting time-fragmented cache attacks against AES using Performance Monitoring Counters
Cache timing attacks use shared caches in multi-core processors as side
channels to extract information from victim processes. These attacks are
particularly dangerous in cloud infrastructures, in which the deployed
countermeasures cause collateral effects in terms of performance loss and
increase in energy consumption. We propose to monitor the victim process using
an independent monitoring (detector) process, that continuously measures
selected Performance Monitoring Counters (PMC) to detect the presence of an
attack. Ad-hoc countermeasures can be applied only when such a risky situation
arises. In our case, the victim process is the AES encryption algorithm and the
attack is performed by means of random encryption requests. We demonstrate that
PMCs are a feasible tool to detect the attack and that sampling PMCs at high
frequencies is worse than sampling at lower frequencies in terms of detection
capabilities, particularly when the attack is fragmented in time to try to be
hidden from detection
Kinetic exchange opinion model: solution in the single parameter map limit
We study a recently proposed kinetic exchange opinion model (Lallouache et.
al., Phys. Rev E 82:056112, 2010) in the limit of a single parameter map.
Although it does not include the essentially complex behavior of the multiagent
version, it provides us with the insight regarding the choice of order
parameter for the system as well as some of its other dynamical properties. We
also study the generalized two- parameter version of the model, and provide the
exact phase diagram. The universal behavior along this phase boundary in terms
of the suitably defined order parameter is seen.Comment: 14 pages, 9 figure
Inter-cluster Thread-to-core Mapping and DVFS on Heterogeneous Multi-cores
Heterogeneous multi-core platforms that contain different types of cores, organized as clusters, are emerging, e.g. ARM's big.LITTLE architecture. These platforms often need to deal with multiple applications, having different performance requirements, executing concurrently. This leads to generation of varying and mixed workloads (e.g. compute and memory intensive) due to resource sharing. Run-time management is required for adapting to such performance requirements and workload variabilities and to achieve energy efficiency. Moreover, the management becomes challenging when the applications are multi-threaded and the heterogeneity needs to be exploited. The existing run-time management approaches do not efficiently exploit cores situated in different clusters simultaneously (referred to as inter-cluster exploitation) and DVFS potential of cores, which is the aim of this paper. Such exploitation might help to satisfy the performance requirement while achieving energy savings at the same time. Therefore, in this paper, we propose a run-time management approach that first selects thread-to-core mapping based on the performance requirements and resource availability. Then, it applies online adaptation by adjusting the voltage-frequency (V-f) levels to achieve energy optimization, without trading-off application performance. For thread-to-core mapping, offline profiled results are used, which contain performance and energy characteristics of applications when executed on the heterogeneous platform by using different types of cores in various possible combinations. For an application, thread-to-core mapping process defines the number of used cores and their type, which are situated in different clusters. The online adaptation process classifies the inherent workload characteristics of concurrently executing applications, incurring a lower overhead than existing learning-based approaches as demonstrated in this paper. The classification of workload is performed using the metric Memory Reads Per Instruction (MRPI). The adaptation process pro-actively selects an appropriate V-f pair for a predicted workload. Subsequently, it monitors the workload prediction error and performance loss, quantified by instructions per second (IPS), and adjusts the chosen V-f to compensate. We validate the proposed run-time management approach on a hardware platform, the Odroid-XU3, with various combinations of multi-threaded applications from PARSEC and SPLASH benchmarks. Results show an average improvement in energy efficiency up to 33% compared to existing approaches while meeting the performance requirements
Successful Surgical Resection of Advanced Gastrointestinal Stromal Tumor Post Neoadjuvent Therapy
We report a case of a 48-year-old Indian male who presented with swelling and firmness in his left upper part of the abdomen of one month duration with anorexia and weight loss. Initial examination revealed an intra abdominal mass of around 16.8x11.0x24.5cm with minimal left sided pleural effusion. A biopsy from the mass confirmed the diagnosis of gastrointestinal stromal tumour (GISTs) as supported by immmunohistochemistry results which showed strong positivity for c-kit while stains for smooth muscle actin, desmin, myoglobin, S100 Protein and cytokerstin remained negative. The patient was not suitable for surgical intervention in view of advanced tumor, and Imatinib Mesylate 400mg daily was started with the aim of making the tumor operable. Such therapy lasted for twenty months and was tolerated well by the patient. It then resulted in gradual tumor regression, following which the patient underwent successful tumor resection. Post surgical resection patient had no radiological evidence of intra abdominal tumor but mild left sided pleural effusion with left lower lobe atelectasis. The patient had uneventful post operative recovery and he is currently on Imatinib mesylate and tolerating treatment well with mild skin rash. The experience with preoperative imatinib on surgical resection rates and post operative outcomes is limited especially with primary locally advanced GISTs. In our case successful surgical resection was possible for a huge locally advanced GIST with unusually prolonged treatment of twenty months with imatinib preoperatively
Arylboronate esters mediated self-healable and biocompatible dynamic G-quadruplex hydrogels as promising 3D-bioinks
Extrudable G-quadruplex hydrogels were prepared at physiological pH. Gels with suitable mechanical properties were explored as 3D-bioinks. The 3D printing process is driven by injectability and the highly thixotropic and self-healable nature of the gel. High cell viability and homogeneous cell distribution within the gel make it a promising material as a 3D bioink
Colossal magnetocapacitance and scale-invariant dielectric response in phase-separated manganites
Thin films of strongly-correlated electron materials (SCEM) are often grown
epitaxially on planar substrates and typically have anisotropic properties that
are usually not captured by edge-mounted four-terminal electrical measurements,
which are primarily sensitive to in-plane conduction paths. Accordingly, the
correlated interactions in the out-of-plane (perpendicular) direction cannot be
measured but only inferred. We address this shortcoming and show here an
experimental technique in which the SCEM under study, in our case a 600
Angstrom-thick (La1-yPry)0.67Ca0.33MnO3 (LPCMO) film, serves as the base
electrode in a metal-insulator-metal (MIM) trilayer capacitor structure. This
unconventional arrangement allows for simultaneous determination of colossal
magnetoresistance (CMR) associated with dc transport parallel to the film
substrate and colossal magnetocapacitance (CMC) associated with ac transport in
the perpendicular direction. We distinguish two distinct strain-related
direction-dependent insulator-metal (IM) transitions and use Cole-Cole plots to
establish a heretofore unobserved collapse of the dielectric response onto a
universal scale-invariant power-law dependence over a large range of frequency,
temperature and magnetic field.Comment: 32 pages, 4 figures, Supplementary section included, Submitted to
Nature Physic
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Characterization of inter-seasonal climatic variability through dry-season rice productivity in the north-west region of Bangladesh
Inter-annual climatic variability in Bangladesh is significant and the probability of occurrence of extreme episodic/ climatic events has increased in the last couple of decades and thus threatening food security. Impact of inter-seasonal climatic va riability on Boro rice (dry season) yield in north-western parts of Bangladesh was analyzed using the historic weather datasets for 1971 to 2010 and MAKESENS model. Boro rice yield increased from 1980 onwards and the growth rate picked up with time. Inter-annual and inter-seasonal climatic variability was noticed through maximum and minimum temperatures, rainfall and sunshine hours. In general, temperatures and rainfall showed increasing trends but sunshine hours were decreasing gradually during the study period. Growth rates in average annual maximum, minimum and mean air temperatures were 0.001, 0.016 and 0.009°C year-1, respectively. On regional scale, Boro-rice seasonal maximum temperature was decreasing by 0.013°C year-1 but minimum and mean temperatures were increasing by 0.024 and 0.006°C year-1, respectively. Annual average sunshine hours in the study location were in decreasing trend by 0.027 hr year-1, but reduction in seasonal sunshine hours was 0.035 hr year-1. Inter-seasonal climatic variability was characterized through the Boro-rice yields in four test regions of north-west region of Bangladesh. Trend line equations were evolved for assessing the impact of climatic variations on Bororice yield. If maximum temperature changes by 1oC, Boro rice yield could be increased by 0.13 t ha-1, but it would reduce by 0.34 t ha-1 with one degree rise in minimum temperature. If sunshine hour decreases by 1 hr, Boro rice yield would decrease by 0.70 t ha-1 in study locations. Combined effects of maximum and minimum temperatures and sunshine hours showed significant influence on grain yields of Boro rice. These imply that temperature tolerant and solar radiation use-efficient rice varieties need to be bred for combating climate change impact in Bangladesh. There is a need to identify optimum sowing/transplanting window for the region, choice of suitable cultivars/ideo-types, and adoption of appropriate water and nutrients management strategies and adoption of appropriate resource conservation technologies for sustainable Boro rice production in Bangladesh
Etiological Profile and Treatment Outcome of Epistaxis at a Tertiary Care Hospital in Northwestern Tanzania: A Prospective Review of 104 Cases.
Epistaxis is the commonest otolaryngological emergency affecting up to 60% of the population in their lifetime, with 6% requiring medical attention. There is paucity of published data regarding the management of epistaxis in Tanzania, especially the study area. This study was conducted to describe the etiological profile and treatment outcome of epistaxis at Bugando Medical Centre, a tertiary care hospital in Northwestern Tanzania. This was a prospective descriptive study of the cases of epistaxis managed at Bugando Medical Centre from January 2008 to December 2010. Data collected were analyzed using SPSS computer software version 15. A total of 104 patients with epistaxis were studied. Males were affected twice more than the females (2.7:1). Their mean age was 32.24 ± 12.54 years (range 4 to 82 years). The modal age group was 31-40 years. The commonest cause of epistaxis was trauma (30.8%) followed by idiopathic (26.9%) and hypertension (17.3%). Anterior nasal bleeding was noted in majority of the patients (88.7%). Non surgical measures such as observation alone (40.4%) and anterior nasal packing (38.5%) were the main intervention methods in 98.1% of cases. Surgical measures mainly intranasal tumor resection was carried out in 1.9% of cases. Arterial ligation and endovascular embolization were not performed. Complication rate was 3.8%. The overall mean of hospital stay was 7.2 ± 1.6 days (range 1 to 24 days). Five patients died giving a mortality rate of 4.8%. Trauma resulting from road traffic crush (RTC) remains the most common etiological factor for epistaxis in our setting. Most cases were successfully managed with conservative (non-surgical) treatment alone and surgical intervention with its potential complications may not be necessary in most cases and should be the last resort. Reducing the incidence of trauma from RTC will reduce the incidence of emergency epistaxis in our centre
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