Objective: To compare the fertilization rates and pregnancy rates (PRs) in intracytoplasmic sperm... more Objective: To compare the fertilization rates and pregnancy rates (PRs) in intracytoplasmic sperm injection (ICSI) using sperm from ejaculates of normal and abnormal semen, epididymal sperm, and testicular sperm of obstructive and nonobstructive azoospermic patients.Design: Retrospective study.Setting: The Egyptian IVF-ET Center.Patient(s): Three hundred fifty patients underwent 366 ICSI cycles.Intervention(s): ICSI, epididymal sperm aspiration, and testicular biopsy. Main Outcome Measure(s): Fertilization rates and PRs.Result(s): Patients were divided into five groups according to the quality and source of sperm. Patients in group 1 underwent 102 cycles of ICSI using ejaculated abnormal semen, group 2 underwent 44 cycles using epididymal sperm, group 3 underwent 82 cycles using testicular sperm from obstructive azoospermia, group 4 underwent 80 cycles using testicular sperm from nonobstructive azoospermia, and group 5 underwent 58 cycles using normal semen. There was no significant difference in the fertilization rates and PRs among groups 1, 2, and 3. In group 4, the fertilization rate and PR were significantly lower than in all other groups. In group 5, the fertilization rate was significantly higher than in all other groups.Conclusion(s): The fertilizing ability of sperm in ICSI is highest with normal semen and lowest with sperm extracted from a testicular biopsy in nonobstructive azoospermia. There was no significant difference in fertilization rates and PRs between ejaculated sperm of different parameters and surgically retrieved sperm in obstructive azoospermia.
This was a retrospective study of 115 patients who underwent 124 cycles of ICSI using surgically ... more This was a retrospective study of 115 patients who underwent 124 cycles of ICSI using surgically retrieved spermatozoa. The objective was to compare the results of ICSI in patients with obstructive azoospermia using epididymal spermatozoa (36 cycles) or testicular spermatozoa (58 cycles) with ICSI in patients with non-obstructive azoospermia using testicular spermatozoa (30 cycles). When epididymal spermatozoa were used for ICSI, the fertilization rate per injected metaphase-II oocyte and the clinical pregnancy rate per ICSI cycle were 60.4 and 25%, respectively. When testicular spermatozoa were used in obstructive cases, the fertilization rate and pregnancy rate were 57.9 and 34.5%. In non-obstructive cases the fertilization and pregnancy rates were 41.2 and 16.6%. When patients with obstructive azoospermia were regrouped according to the cause of obstruction, the fertilization and pregnancy rates were 59.1 and 35.1% in acquired obstruction and 58.7 and 24.3% in congenital obstruction. The fertilization and pregnancy rates were not statistically different (p > 0.05) when testicular or epididymal spermatozoa were used in obstructive cases; neither was statistically different (p > 0.05) when compared in patients with congenital and acquired obstruction. On the other hand, the fertilization and pregnancy rates in cases with non-obstructive azoospermia were significantly lower (p < 0.05) than in obstructive cases.
A fundamental challenge in the design of wireless sensor networks (WSNs) is to maximize their lif... more A fundamental challenge in the design of wireless sensor networks (WSNs) is to maximize their lifetimes. Data aggregation has emerged as a basic approach in WSNs in order to reduce the number of transmissions of sensor nodes, and hence minimizing the overall power consumption in the network. We study optimal data aggregation in WSNs. Data aggregation is affected by several factors, such as the placement of aggregation points, the aggregation function, and the density of sensors in the network. The determination of an optimal selection of aggregation points is thus extremely important. We present exact and approximate algorithms to find the minimum number of aggregation points in order to maximize the network lifetime. Our algorithms use a fixed virtual wireless backbone that is built on top of the physical topology. We also study the tradeoffs between energy savings and the potential delay involved in the data aggregation process. Numerical results show that our approach provides substantial energy savings.
A fundamental challenge in the design of wireless sensor networks (WSNs) is to maximize their lif... more A fundamental challenge in the design of wireless sensor networks (WSNs) is to maximize their lifetimes. Since many sensors have correlated readings, data aggregation has emerged as an efficient approach to reduce the number of transmissions, and hence minimize overall power consumption in the network. An important aspect of data aggregation is the placement of aggregation points and how aggregated data is routed to the gathering points. In this paper, we consider the problem of correlated data gathering in WSNs with the objective of minimizing the total transmission cost in terms of power consumption. We particularly focus on the problem of finding the set of aggregation points that satisfy our objective. Two solution strategies are presented: an exact solution using an integer linear program (ILP) formulation and a near optimal, but simple and efficient heuristic, called load balancing with aggregation (LISA). Our solutions use a fixed virtual wireless backbone that is built on top of the physical topology. Numerical results show that our proposed scheme provides substantial energy savings when compared to other schemes.
A mobile ad hoc network (MANET) can be represented by a set of logical clusters with clusterheads... more A mobile ad hoc network (MANET) can be represented by a set of logical clusters with clusterheads (CHs) acting like virtual base-stations, hence forming a wireless virtual backbone. The role of clusterhead is a temporary one, which changes dynamically as the topology or other factors affecting it change. Finding the minimal set of CHs is an NP-complete problem. We study the performance tradeoffs between two clustering approaches. The first one is a simple clustering strategy, called virtual grid architecture (VGA), which is based on a fixed rectilinear virtual topology, while the second one is an optimal clustering strategy. We consider homogeneous as well as heterogeneous networks. First, for homogeneous MANETs with a large number of users and under the VGA clustering approach, we derive expressions for the number of CHs, worst case path length, and average case path length. We also derive expressions for the communication overhead. Second, we develop an integer linear program (ILP) that finds the optimal number of connected CHs in small to medium sized heterogeneous MANETs. Analytical and simulation results show that our proposed clustering algorithm (VGA), although being simple, is close to optimal.
IEEE Journal on Selected Areas in Communications, 2006
Page 1. IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 24, NO. 4, APRIL 2006 37 Design an... more Page 1. IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 24, NO. 4, APRIL 2006 37 Design and Provisioning of WDM Networks with Multicast Traffic Grooming Raza Ul-Mustafa, Member, IEEE, and Ahmed E. Kamal, Senior Member, IEEE ...
This paper considers the problem of grooming multicast traffic in WDM networks, with arbitrary me... more This paper considers the problem of grooming multicast traffic in WDM networks, with arbitrary mesh topologies. The problem is different from grooming of unicast traffic, since traffic can be delivered to destinations through other destinations in the same set, or through branching points. The paper presents an optimal Integer Linear Programming (ILP) formulation in order to minimize the cost of the network in terms of the number of SONET Add/Drop Multiplexers (ADM). The formulation also minimizes the number of wavelength channels used in the network, and does not allow bifurcation of traffic. Since the ILP formulation is able to solve limited size problems, the paper also introduces a heuristic approach to solve the problem.
Objective: To compare the fertilization rates and pregnancy rates (PRs) in intracytoplasmic sperm... more Objective: To compare the fertilization rates and pregnancy rates (PRs) in intracytoplasmic sperm injection (ICSI) using sperm from ejaculates of normal and abnormal semen, epididymal sperm, and testicular sperm of obstructive and nonobstructive azoospermic patients.Design: Retrospective study.Setting: The Egyptian IVF-ET Center.Patient(s): Three hundred fifty patients underwent 366 ICSI cycles.Intervention(s): ICSI, epididymal sperm aspiration, and testicular biopsy. Main Outcome Measure(s): Fertilization rates and PRs.Result(s): Patients were divided into five groups according to the quality and source of sperm. Patients in group 1 underwent 102 cycles of ICSI using ejaculated abnormal semen, group 2 underwent 44 cycles using epididymal sperm, group 3 underwent 82 cycles using testicular sperm from obstructive azoospermia, group 4 underwent 80 cycles using testicular sperm from nonobstructive azoospermia, and group 5 underwent 58 cycles using normal semen. There was no significant difference in the fertilization rates and PRs among groups 1, 2, and 3. In group 4, the fertilization rate and PR were significantly lower than in all other groups. In group 5, the fertilization rate was significantly higher than in all other groups.Conclusion(s): The fertilizing ability of sperm in ICSI is highest with normal semen and lowest with sperm extracted from a testicular biopsy in nonobstructive azoospermia. There was no significant difference in fertilization rates and PRs between ejaculated sperm of different parameters and surgically retrieved sperm in obstructive azoospermia.
This was a retrospective study of 115 patients who underwent 124 cycles of ICSI using surgically ... more This was a retrospective study of 115 patients who underwent 124 cycles of ICSI using surgically retrieved spermatozoa. The objective was to compare the results of ICSI in patients with obstructive azoospermia using epididymal spermatozoa (36 cycles) or testicular spermatozoa (58 cycles) with ICSI in patients with non-obstructive azoospermia using testicular spermatozoa (30 cycles). When epididymal spermatozoa were used for ICSI, the fertilization rate per injected metaphase-II oocyte and the clinical pregnancy rate per ICSI cycle were 60.4 and 25%, respectively. When testicular spermatozoa were used in obstructive cases, the fertilization rate and pregnancy rate were 57.9 and 34.5%. In non-obstructive cases the fertilization and pregnancy rates were 41.2 and 16.6%. When patients with obstructive azoospermia were regrouped according to the cause of obstruction, the fertilization and pregnancy rates were 59.1 and 35.1% in acquired obstruction and 58.7 and 24.3% in congenital obstruction. The fertilization and pregnancy rates were not statistically different (p > 0.05) when testicular or epididymal spermatozoa were used in obstructive cases; neither was statistically different (p > 0.05) when compared in patients with congenital and acquired obstruction. On the other hand, the fertilization and pregnancy rates in cases with non-obstructive azoospermia were significantly lower (p < 0.05) than in obstructive cases.
A fundamental challenge in the design of wireless sensor networks (WSNs) is to maximize their lif... more A fundamental challenge in the design of wireless sensor networks (WSNs) is to maximize their lifetimes. Data aggregation has emerged as a basic approach in WSNs in order to reduce the number of transmissions of sensor nodes, and hence minimizing the overall power consumption in the network. We study optimal data aggregation in WSNs. Data aggregation is affected by several factors, such as the placement of aggregation points, the aggregation function, and the density of sensors in the network. The determination of an optimal selection of aggregation points is thus extremely important. We present exact and approximate algorithms to find the minimum number of aggregation points in order to maximize the network lifetime. Our algorithms use a fixed virtual wireless backbone that is built on top of the physical topology. We also study the tradeoffs between energy savings and the potential delay involved in the data aggregation process. Numerical results show that our approach provides substantial energy savings.
A fundamental challenge in the design of wireless sensor networks (WSNs) is to maximize their lif... more A fundamental challenge in the design of wireless sensor networks (WSNs) is to maximize their lifetimes. Since many sensors have correlated readings, data aggregation has emerged as an efficient approach to reduce the number of transmissions, and hence minimize overall power consumption in the network. An important aspect of data aggregation is the placement of aggregation points and how aggregated data is routed to the gathering points. In this paper, we consider the problem of correlated data gathering in WSNs with the objective of minimizing the total transmission cost in terms of power consumption. We particularly focus on the problem of finding the set of aggregation points that satisfy our objective. Two solution strategies are presented: an exact solution using an integer linear program (ILP) formulation and a near optimal, but simple and efficient heuristic, called load balancing with aggregation (LISA). Our solutions use a fixed virtual wireless backbone that is built on top of the physical topology. Numerical results show that our proposed scheme provides substantial energy savings when compared to other schemes.
A mobile ad hoc network (MANET) can be represented by a set of logical clusters with clusterheads... more A mobile ad hoc network (MANET) can be represented by a set of logical clusters with clusterheads (CHs) acting like virtual base-stations, hence forming a wireless virtual backbone. The role of clusterhead is a temporary one, which changes dynamically as the topology or other factors affecting it change. Finding the minimal set of CHs is an NP-complete problem. We study the performance tradeoffs between two clustering approaches. The first one is a simple clustering strategy, called virtual grid architecture (VGA), which is based on a fixed rectilinear virtual topology, while the second one is an optimal clustering strategy. We consider homogeneous as well as heterogeneous networks. First, for homogeneous MANETs with a large number of users and under the VGA clustering approach, we derive expressions for the number of CHs, worst case path length, and average case path length. We also derive expressions for the communication overhead. Second, we develop an integer linear program (ILP) that finds the optimal number of connected CHs in small to medium sized heterogeneous MANETs. Analytical and simulation results show that our proposed clustering algorithm (VGA), although being simple, is close to optimal.
IEEE Journal on Selected Areas in Communications, 2006
Page 1. IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 24, NO. 4, APRIL 2006 37 Design an... more Page 1. IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 24, NO. 4, APRIL 2006 37 Design and Provisioning of WDM Networks with Multicast Traffic Grooming Raza Ul-Mustafa, Member, IEEE, and Ahmed E. Kamal, Senior Member, IEEE ...
This paper considers the problem of grooming multicast traffic in WDM networks, with arbitrary me... more This paper considers the problem of grooming multicast traffic in WDM networks, with arbitrary mesh topologies. The problem is different from grooming of unicast traffic, since traffic can be delivered to destinations through other destinations in the same set, or through branching points. The paper presents an optimal Integer Linear Programming (ILP) formulation in order to minimize the cost of the network in terms of the number of SONET Add/Drop Multiplexers (ADM). The formulation also minimizes the number of wavelength channels used in the network, and does not allow bifurcation of traffic. Since the ILP formulation is able to solve limited size problems, the paper also introduces a heuristic approach to solve the problem.
Uploads
Papers by Ahmed Kamal