Hashim Mohamed

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Papers by Hashim Mohamed

The Design and Implementation of the KOALA Co-allocating Grid Scheduler

Lecture Notes in Computer Science, 2005

Abstract. In multicluster systems, and more generally, in grids, jobs may require co-allocation, ... more

Enhancing primary healing post ray amputation in a diabetic patient: efficacy of natural honey

Ray amputation is a common surgical procedure performed on diabetic patients suffering from osteo... more Ray amputation is a common surgical procedure performed on diabetic patients suffering from osteomyelitis-complicating diabetic foot ulcers. This report seeks to introduce a novel alternative to the range of existing wound dressing materials commonly used to manage post ray amputation wounds. Post-amputation, and after flushing the wound with normal saline and using a scalpel to perform proper sharp debridement, natural honey was applied. Following the application of natural honey, a sterile gauze was applied and the dressing was changed on a daily basis. Four weeks after applying natural honey on a daily basis, the wound had completely healed, by secondary intention. Using natural honey can promote wound healing by secondary intention and therefore provides a natural, efficacious, and cost effective alternative to the existing expensive wound dressing materials available on the market. This is important since Type 2 diabetes, and its complications such as diabetic foot ulcers, is a...

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Experiences with the KOALA co-allocating scheduler in multiclusters

CCGrid 2005. IEEE International Symposium on Cluster Computing and the Grid, 2005., 2005

In multicluster systems, and more generally, in grids, jobs may require co-allocation, ie, the si... more

The Efficacy and Safety of Natural Honey on the Healing of Foot Ulcers: A Case Series

by Nour Barakat and Hashim Mohamed

Wounds : a compendium of clinical research and practice, 2015

This clinical observation investigated the efficacy, cost-effectiveness, and acceptability of nat... more This clinical observation investigated the efficacy, cost-effectiveness, and acceptability of natural honey on the healing of a variety of chronic foot ulcers at the primary care level. A total of 12 patients with foot ulcers utilizing natural honey as an effective alternative to more expensive, advanced wound products were followed. Cases were referred to Umgwailinah Primary Health Care Center, Doha, Qatar from different health centers and from Hamad General Hospital, Doha, Qatar. There were also self-referred cases. After rinsing the site with normal saline, natural honey was applied and the wound was covered by glycerin-impregnated gauze (Adaptic Non-Adhering Dressing, Systagenix, San Antonio, TX) to prevent the absorption of honey into the cotton gauze and away from the wound site. Patients were followed on a daily basis for an average of 4 weeks. All ulcers healed with no contractures or scars with a mean healing time of 3 weeks. There was a 75% reduction in the dressing budget...

Knowledge, attitude, and practice of type2 Arab diabetic patients in Qatar: a cross-sectional study

by Hashim Mohamed and Nour Barakat

International Journal of Diabetes in Developing Countries, 2015

On the Benefit of Processor Co-Allocation in Multicluster Grid Systems

In multicluster grid systems, parallel applications may benefit from processor co-allocation, tha... more In multicluster grid systems, parallel applications may benefit from processor co-allocation, that is, the simulta- neous allocation of processors in multiple clusters. Although co-allocation allows the allocation of more processors than available in a single cluster, it may severely increase the ex- ecution time of applications due to the relatively slow wide- area communication. The aim of this paper is

A Dynamic Co-allocation Service in Multicluster Systems

Job Scheduling Strategies for Parallel Processing, 2004

In multicluster systems, and more generally in grids, jobs may require co-allocation, i.e., the s... more In multicluster systems, and more generally in grids, jobs may require co-allocation, i.e., the simultaneous all o- cation of resources such as processors in multiple clusters to improve their performance. In previous work, we have studied processor co-allocation through simulations. Her e, we extend this work with the design and implementation of a dynamic processor co-allocation service in multicluster systems.

Communication-Aware Job Placement Policies for the KOALA Grid Scheduler

2006 Second IEEE International Conference on e-Science and Grid Computing (e-Science'06), 2006

In multicluster systems, and more generally, in grids, parallel applications may require co-alloc... more

Scheduling malleable applications in multicluster systems

by Hashim Mohamed and Wouter Lammers

2007 IEEE International Conference on Cluster Computing, 2007

In large-scale distributed execution environments such as multicluster systems and grids, resourc... more In large-scale distributed execution environments such as multicluster systems and grids, resource availability may vary due to resource failures and because resources may be added to or withdrawn from such environments at any time. In addition, single sites in such systems may have to deal with workloads originating from both local users and from many other sources. As a result, application malleability, that is, the property of applications to deal with a varying amount of resources during their execution, may be very beneficial for performance. In this paper we present the design of the support of and scheduling policies for malleability in our KOALA multicluster scheduler with the help of our DYNACO framework for application malleability. In addition, we show the results of experiments with scheduling malleable workloads with KOALA in our DAS multicluster testbed.

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Co-Allocation in Grids: Experiences and Issues

Future Generation Grids, 2006

Jobs submitted to a grid may require more resources than those available at any time in any singl... more

An evaluation of the close-to-files processor and data co-allocation policy in multiclusters

In multicluster systems, and more generally, in grids, jobs may require co-allocation, i.e., the ... more In multicluster systems, and more generally, in grids, jobs may require co-allocation, i.e., the simultaneous allocation of resources such as processors and input files in multiple clusters. While such jobs may have reduced runtimes be- cause they have access to more resources, waiting for pro- cessors in multiple clusters and for the input files to become available in the right locations may introduce inefficiencies. In previous work, we have studied through simulations only processor co-allocation. Here, we extend this work with an analysis of the performance in a real testbed of our proto- type Processor and Data Co-Allocator with the Close-to- Files (CF) job-placement algorithm. CF tries to place job components on clusters with enough idle processors which are close to the sites where the input files reside. We present a comparison of the performance of CF and the Worst-Fit job-placement algorithm, with and without file replication, achieved with our prototype. Our most importan...

Culturally sensitive patient-centred educational programme for self-management of type 2 diabetes: A randomized controlled trial

Primary Care Diabetes, 2013

To assess the effectiveness of a culturally sensitive, structured education programme (CSSEP) on ... more To assess the effectiveness of a culturally sensitive, structured education programme (CSSEP) on biomedical, knowledge, attitude and practice measures among Arabs with type two diabetes. A total of 430 patients with type II diabetes mellitus living in Doha, Qatar were enrolled in the study. They were randomized to either intervention (n = 215) or a control group (n = 215). A baseline and one-year interval levels of biomedical variables including HbA1C, lipid profile, urine for microalbuminuria; in addition to knowledge, attitude and practice (KAP) scores were prospectively measured. The intervention was based on theory of empowerment, health belief models and was culturally sensitive in relation to language (Arabic), food habits and health beliefs. It consisted of four educational sessions for each group of patients (10-20 patients per session), lasting for 3-4 h. The first session discussed diabetes pathophysiology and complications; while the second session discussed healthy life style incorporating the Idaho plate method; and the third session dealt with exercise benefits and goal setting and the fourth session concentrated enhancing attitude and practice using counselling techniques. Outcomes were assessed at base line and 12 months after intervention. After 12 months participation in the intervention was shown to have led to a statistically significant reduction in HbA1C in the (CSSEP) group (-0.55 mmol/L, P = 0.012), fasting blood sugar (-0.92 mmol/L, P = 0.022), body mass index (1.70, P = 0.001) and albumin/creatinine ratio (-3.09, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.0001) but not in the control group. The intervention group also had improvement in Diabetes knowledge (5.9%, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.0001), attitude (6.56%, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.0001), and practice (6.52%, P = 0.0001). This study demonstrates the effectiveness of culturally sensitive, structured, group-based diabetes education in enhancing biomedical and behavioural outcomes in Diabetic patients.

Honey based therapy for the management of a recalcitrant diabetic foot ulcer

Journal of Tissue Viability, 2014

Diabetic foot ulcers are usually treated at hospital podiatry clinics and not at primary care lev... more Diabetic foot ulcers are usually treated at hospital podiatry clinics and not at primary care level. We report an alternative approach using honey based therapy in the successful management of diabetic foot ulcer at primary health care level. The case is discussed in relation to various modalities targeting diabetic foot ulceration in the literature. A 65 years old female-Egyptian diabetic patient presented with a neuropathic plantar ulcer of 10 × 5 cm post-thermal burn following the use of a hot water bottle. The patient was treated with strict offloading using a pair of crutches, debridement of necrotic tissue using a sharp scalpel and commercial honey applied daily and covered with a glycerin based dressing. The honey dressing was changed daily along with strict offloading and by week 16 the ulcer completely healed. Treatment of diabetic foot ulcer is possible at primary care level.

On the Benefit of Processor Coallocation in Multicluster Grid Systems

IEEE Transactions on Parallel and Distributed Systems, 2000

AbstractIn multicluster grid systems, parallel applications may benefit from processor coallocat... more

KOALA: a co-allocating grid scheduler

Concurrency and Computation: Practice and Experience, 2008

In multicluster systems, and more generally in grids, jobs may require co-allocation, that is, th... more In multicluster systems, and more generally in grids, jobs may require co-allocation, that is, the simultaneous or coordinated access of single applications to resources of possibly multiple types in multiple locations managed by different resource managers. Co-allocation presents new challenges to resource management in grids, such as locating sufficient resources in geographically distributed sites, allocating and managing resources in multiple, possibly heterogeneous sites for single applications, and coordinating the execution of single jobs at multiple sites. Moreover, as single jobs now may have to rely on multiple resource managers, co-allocation introduces reliability problems. In this paper, we present the design and implementation of a co-allocating grid scheduler named KOALA that meets these co-allocation challenges. In addition, we report on the results of an analysis of the performance in our multicluster testbed of the co-allocation policies built into KOALA. We also include the results of a performance and reliability test of KOALA while our testbed was unstable.

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Simulating grid schedulers with deadlines and co-allocation

One of the true challenges in resource management in grids is to provide support for co-allocatio... more One of the true challenges in resource management in grids is to provide support for co-allocation, that is, the allocation of resources in multiples autonomous subsystems of a grid to single jobs. With reservation-based local schedulers, a grid scheduler can reserve processors with these schedulers to achieve simultaneous processor availability. However, with queuing-based local schedulers, it is much more difficult to guarantee this. In this paper we present mechanisms and policies for working around the lack of reservation mechanisms for jobs with deadlines that require co-allocation, and simulations of these mechanisms and policies.

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Scheduling strategies for cycle scavenging in multicluster grid systems

by Hashim Mohamed and B. Grundeken

The use of today's multicluster grids exhibits periods of submission bursts with periods of norma... more The use of today's multicluster grids exhibits periods of submission bursts with periods of normal use and even of idleness. To avoid resource contention, many users employ observational scheduling, that is, they postpone the submission of relatively low-priority jobs until a cluster becomes (largely) idle. However, observational scheduling leads to resource contention when several such users crowd the same idle cluster. Moreover, this job execution model either delays the execution of more important jobs, or requires extensive administrative support for job and user priorities. Instead, in this work we investigate the use of cycle scavenging to run jobs on grid resources politely yet efficiently, and with an acceptable administrative cost. We design a twolevel cycle scavenging scheduling architecture that runs unobtrusively alongside regular grid scheduling. We equip this scheduler with two novel cycle scavenging scheduling policies that enforce fair resource sharing among competing cycle scavenging users. We show through experiments with real and synthetic applications in a real multi-cluster grid that the proposed architecture can execute jobs politely yet efficiently.

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ServMark: A Framework for Testing Grid Services

by Catalin Dumitrescu and Hashim Mohamed

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Virtual Domain Sharing in e-Science based on Usage Service Level Agreements

by Catalin Dumitrescu and Hashim Mohamed

Towards Next Generation Grids, 2007

The explosion of freely available media content through BitTorrent file sharing networks over the... more The explosion of freely available media content through BitTorrent file sharing networks over the Internet means that users need guides or recommendations to find the right, high quality, content. Current systems rely on centralized servers to aggregate, rate and moderate metadata for this purpose. We present the design and simulations, using real BitTorrent traces, for a method combining fully decentralized metadata dissemination, vote sampling and ranking for deployment in the Tribler.org BitTorrent media client. Our design provides robustness to spam attacks, where metadata does not reflect the content it is attached to, by controlling metadata spreading and by vote sampling based on a collusion proof experience function. Our design is light-weight, fully decentralized and offers good performance and robustness under realistic conditions.

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