Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology, 2010
Objective. To investigate the 3-dimensional (3D) changes in the soft tissue after mandibular setb... more Objective. To investigate the 3-dimensional (3D) changes in the soft tissue after mandibular setback surgery (MSS). Study design. Thirty-three skeletal class III malocclusion (SCIII) patients treated with MSS (bilateral sagittal split ramus osteotomy) were subdivided according to extent of MSS, vertical skeletal pattern (VP), and vertical-reduction genioplasty. Lateral cephalograms and 3D facial scan images were taken before and 6 months after surgery. Linear and angular variables were measured with Rapidform 2006 (Inus Technology). Results. After MSS, there were significant increases in the upper lip length and decreases in the lower lip length in the large setback, hypodivergent, and genioplasty groups. The mentolabial fold deepened less in the genioplasty group than in other groups. Although there was no skeletal advancement of the maxilla, the soft tissue convexity in the paranasal area increased more in the hyperdivergent group than in the hypodivergent group after MSS. Conclusion. The extent of MSS, VP, and genioplasty could be used as guidelines for 1-and 2-jaw surgeries in SCIII borderline cases.
We assessed the implication of Th (helper)-cells and the modulation of the Th1/Th2 dichotomy by n... more We assessed the implication of Th (helper)-cells and the modulation of the Th1/Th2 dichotomy by n-3 polyunsaturated fatty acids (PUFA) in type I diabetic pregnancy (DP) and macrosomia. Female gestant rats fed a standard diet or n-3 PUFA regimen were rendered diabetic by administration of five low doses of streptozotocin. The macrosomic (MAC) offspring were sacrificed at the age of 90 days. The mRNAs of IL-2 and IFN-g (Th1 cytokines) and IL-4 (Th2 cytokine) were downregulated in the pancreas and spleen of diabetic pregnant rats. The levels of IL-10 mRNA, another Th2 cytokine, were unchanged in the spleen or upregulated in the pancreas of these animals. Feeding an n-3 PUFA diet to rats with DP upregulated IL-10 mRNA in the pancreas and IL-4 and IL-10 mRNA in the spleen. In MAC offspring, high expression of IL-2 and IFN-g mRNA, but not of Th2 cytokines, was observed. The n-3 PUFA diet diminished Th1 mRNA quantities and increased the levels of IL-4, but not of IL-10, mRNA in MAC offspring. Our study shows that DP is associated with a decreased Th1 phenotype and IL-4 mRNA expression in the pancreas and spleen, and an n-3 PUFA diet upregulates Th2 profile. In MAC offspring, the Th1 phenotype is upregulated and an n-3 PUFA diet downregulates this phenomenon.
We resolve the question of optimality for a wellstudied packetized implementation of random linea... more We resolve the question of optimality for a wellstudied packetized implementation of random linear network coding, called PNC. In PNC, in contrast to the classical memoryless setting, nodes store received information in memory to later produce coded packets that reflect this information. PNC is known to achieve order optimal stopping times for the manyto-all multicast problem in many settings.
We present a graph theoretic upper bound on speedup needed to achieve 100% throughput in a multic... more We present a graph theoretic upper bound on speedup needed to achieve 100% throughput in a multicast switch using network coding. By bounding speedup, we show the equivalence between network coding and speedup in multicast switchesi.e. network coding, which is usually implemented using software, can in many cases substitute speedup, which is often achieved by adding extra switch fabrics. This bound is based on an approach to network coding problems called the "enhanced conflict graph". We show that the "imperfection ratio" of the enhanced conflict graph gives an upper bound on speedup. In particular, we apply this result to K × N switches with traffic patterns consisting of unicasts and broadcasts only to obtain an upper bound of min( 2K−1 K , 2N N +1 ).
In this paper, we propose a scheme, called the algebraic watchdog for wireless network coding, in... more In this paper, we propose a scheme, called the algebraic watchdog for wireless network coding, in which nodes can detect malicious behaviors probabilistically, police their downstream neighbors locally using overheard messages, and, thus, provide a secure global self-checking network. Unlike traditional Byzantine detection protocols which are receiver-based, this protocol gives the senders an active role in checking the node downstream. This work is inspired by Marti et al.'s watchdogpathrater, which attempts to detect and mitigate the effects of routing misbehavior.
In this paper, we propose a scheme, called the algebraic watchdog for wireless network coding, in... more In this paper, we propose a scheme, called the algebraic watchdog for wireless network coding, in which nodes can detect malicious behaviors probabilistically, police their downstream neighbors locally using overheard messages, and, thus, provide a secure global self-checking network. Unlike traditional Byzantine detection protocols which are receiver-based, this protocol gives the senders an active role in checking the node downstream. This work is inspired by Marti et al.'s watchdogpathrater, which attempts to detect and mitigate the effects of routing misbehavior.
The problem of serving multicast flows in a crossbar switch is considered. Intra-flow linear netw... more The problem of serving multicast flows in a crossbar switch is considered. Intra-flow linear network coding is shown to achieve a larger rate region than the case without coding. A traffic pattern is presented which is achievable with coding but requires a switch speedup when coding is not allowed. The rate region with coding can be characterized in a simple graph-theoretic manner, in terms of the stable set polytope of the "enhanced conflict graph". No such graph-theoretic characterization is known for the case of fanout splitting without coding.
Finally, we extend the ADT networks to those with random erasures and cycles (thus, allowing bi-d... more Finally, we extend the ADT networks to those with random erasures and cycles (thus, allowing bi-directional links). Note that ADT network was proposed for approximating the wireless networks; however, ADT network is acyclic. Furthermore, ADT network does not model the stochastic nature of the wireless links. With our algebraic framework, we incorporate both cycles as well as random failures into ADT network model.
IEEE Journal on Selected Areas in Communications, 2010
Random linear network coding can be used in peerto-peer networks to increase the efficiency of co... more Random linear network coding can be used in peerto-peer networks to increase the efficiency of content distribution and distributed storage. However, these systems are particularly susceptible to Byzantine attacks. We quantify the impact of Byzantine attacks on the coded system by evaluating the probability that a receiver node fails to correctly recover a file. We show that even for a small probability of attack, the system fails with overwhelming probability. We then propose a novel signature scheme that allows packet-level Byzantine detection. This scheme allows one-hop containment of the contamination, and saves bandwidth by allowing nodes to detect and drop the contaminated packets. We compare the net cost of our signature scheme with various other Byzantine schemes, and show that when the probability of Byzantine attacks is high, our scheme is the most bandwidth efficient.
We present a graph theoretic upper bound on speedup needed to achieve 100% throughput in a multic... more We present a graph theoretic upper bound on speedup needed to achieve 100% throughput in a multicast switch using network coding. By bounding speedup, we show the equivalence between network coding and speedup in multicast switches - i.e. network coding, which is usually implemented using software, can in many cases substitute speedup, which is often achieved by adding extra switch fabrics. This bound is based on an approach to network coding problems called the "enhanced conflict graph". We show that the "imperfection ratio" of the enhanced conflict graph gives an upper bound on speedup. In particular, we apply this result to K times N switches with traffic patterns consisting of unicasts and broadcasts only to obtain an upper bound of min(2K-1/K, 2N/N+1).
We consider the problem of serving multicast flows in a crossbar switch. We show that linear netw... more We consider the problem of serving multicast flows in a crossbar switch. We show that linear network coding across packets of a flow can sustain traffic patterns that cannot be served if network coding were not allowed. Thus, network coding leads to a larger rate region in a multicast crossbar switch. We demonstrate a traffic pattern which requires a switch speedup if coding is not allowed, whereas, with coding the speedup requirement is eliminated completely. In addition to throughput benefits, coding simplifies the characterization of the rate region. We give a graph-theoretic characterization of the rate region with fanout splitting and intra-flow coding, in terms of the stable set polytope of the 'enhanced conflict graph' of the traffic pattern. Such a formulation is not known in the case of fanout splitting without coding. We show that computing the offline schedule (i.e. using prior knowledge of the flow arrival rates) can be reduced to certain graph coloring problems. Finally, we propose online algorithms (i.e. using only the current queue occupancy information) for multicast scheduling based on our graph-theoretic formulation. In particular, we show that a maximum weighted stable set algorithm stabilizes the queues for all rates within the rate region.
The problem of serving multicast flows in a crossbar switch is considered. Intraflow linear netwo... more The problem of serving multicast flows in a crossbar switch is considered. Intraflow linear network coding is shown to achieve a larger rate region than the case without coding. A traffic pattern is presented which is achievable with coding but requires a switch speedup when coding is not allowed. The rate region with coding can be characterized in a simple graph-theoretic manner, in terms of the stable set polytope of the "enhanced conflict graph". No such graph-theoretic characterization is known for the case of fanout-splitting without coding. The minimum speedup needed to achieve 100% throughput with coding is shown to be upper bounded by the imperfection ratio of the enhanced conflict graph, where the imperfection ratio measures a certain graph theoretic property of the given graph. When applied to K × N switches with unicasts and broadcasts only, this gives a bound of min(2K-1/K, 2N/N+1) on the speedup. This shows that speedup, which is usually implemented in hardware, can often be substituted by network coding, which can be done in software. Computing an offline schedule (using prior knowledge of the flow rates) is reduced to fractional weighted graph coloring. A graph-theoretic online scheduling algorithm (using only queue occupancy information) is also proposed, that stabilizes the queues for all rates within the rate region.
Multi-resolution codes enable multicast at different rates to different receivers, a setup that i... more Multi-resolution codes enable multicast at different rates to different receivers, a setup that is often desirable for graphics or video streaming. We propose a simple, distributed, two-stage message passing algorithm to generate network codes for single-source multicast of multi-resolution codes. The goal of this pushback algorithm is to maximize the total rate achieved by all receivers, while guaranteeing decodability of the base layer at each receiver. By conducting pushback and code assignment stages, this algorithm takes advantage of inter-layer as well as intra-layer coding. Numerical simulations show that in terms of total rate achieved, the pushback algorithm outperforms routing and intra-layer coding schemes, even with field sizes as small as 2 10 (10 bits). In addition, the performance gap widens as the number of receivers and the number of nodes in the network increases. We also observe that naïve inter-layer coding schemes may perform worse than intra-layer schemes under certain network conditions.
Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology, 2010
Objective. To investigate the 3-dimensional (3D) changes in the soft tissue after mandibular setb... more Objective. To investigate the 3-dimensional (3D) changes in the soft tissue after mandibular setback surgery (MSS). Study design. Thirty-three skeletal class III malocclusion (SCIII) patients treated with MSS (bilateral sagittal split ramus osteotomy) were subdivided according to extent of MSS, vertical skeletal pattern (VP), and vertical-reduction genioplasty. Lateral cephalograms and 3D facial scan images were taken before and 6 months after surgery. Linear and angular variables were measured with Rapidform 2006 (Inus Technology). Results. After MSS, there were significant increases in the upper lip length and decreases in the lower lip length in the large setback, hypodivergent, and genioplasty groups. The mentolabial fold deepened less in the genioplasty group than in other groups. Although there was no skeletal advancement of the maxilla, the soft tissue convexity in the paranasal area increased more in the hyperdivergent group than in the hypodivergent group after MSS. Conclusion. The extent of MSS, VP, and genioplasty could be used as guidelines for 1-and 2-jaw surgeries in SCIII borderline cases.
We assessed the implication of Th (helper)-cells and the modulation of the Th1/Th2 dichotomy by n... more We assessed the implication of Th (helper)-cells and the modulation of the Th1/Th2 dichotomy by n-3 polyunsaturated fatty acids (PUFA) in type I diabetic pregnancy (DP) and macrosomia. Female gestant rats fed a standard diet or n-3 PUFA regimen were rendered diabetic by administration of five low doses of streptozotocin. The macrosomic (MAC) offspring were sacrificed at the age of 90 days. The mRNAs of IL-2 and IFN-g (Th1 cytokines) and IL-4 (Th2 cytokine) were downregulated in the pancreas and spleen of diabetic pregnant rats. The levels of IL-10 mRNA, another Th2 cytokine, were unchanged in the spleen or upregulated in the pancreas of these animals. Feeding an n-3 PUFA diet to rats with DP upregulated IL-10 mRNA in the pancreas and IL-4 and IL-10 mRNA in the spleen. In MAC offspring, high expression of IL-2 and IFN-g mRNA, but not of Th2 cytokines, was observed. The n-3 PUFA diet diminished Th1 mRNA quantities and increased the levels of IL-4, but not of IL-10, mRNA in MAC offspring. Our study shows that DP is associated with a decreased Th1 phenotype and IL-4 mRNA expression in the pancreas and spleen, and an n-3 PUFA diet upregulates Th2 profile. In MAC offspring, the Th1 phenotype is upregulated and an n-3 PUFA diet downregulates this phenomenon.
We resolve the question of optimality for a wellstudied packetized implementation of random linea... more We resolve the question of optimality for a wellstudied packetized implementation of random linear network coding, called PNC. In PNC, in contrast to the classical memoryless setting, nodes store received information in memory to later produce coded packets that reflect this information. PNC is known to achieve order optimal stopping times for the manyto-all multicast problem in many settings.
We present a graph theoretic upper bound on speedup needed to achieve 100% throughput in a multic... more We present a graph theoretic upper bound on speedup needed to achieve 100% throughput in a multicast switch using network coding. By bounding speedup, we show the equivalence between network coding and speedup in multicast switchesi.e. network coding, which is usually implemented using software, can in many cases substitute speedup, which is often achieved by adding extra switch fabrics. This bound is based on an approach to network coding problems called the "enhanced conflict graph". We show that the "imperfection ratio" of the enhanced conflict graph gives an upper bound on speedup. In particular, we apply this result to K × N switches with traffic patterns consisting of unicasts and broadcasts only to obtain an upper bound of min( 2K−1 K , 2N N +1 ).
In this paper, we propose a scheme, called the algebraic watchdog for wireless network coding, in... more In this paper, we propose a scheme, called the algebraic watchdog for wireless network coding, in which nodes can detect malicious behaviors probabilistically, police their downstream neighbors locally using overheard messages, and, thus, provide a secure global self-checking network. Unlike traditional Byzantine detection protocols which are receiver-based, this protocol gives the senders an active role in checking the node downstream. This work is inspired by Marti et al.'s watchdogpathrater, which attempts to detect and mitigate the effects of routing misbehavior.
In this paper, we propose a scheme, called the algebraic watchdog for wireless network coding, in... more In this paper, we propose a scheme, called the algebraic watchdog for wireless network coding, in which nodes can detect malicious behaviors probabilistically, police their downstream neighbors locally using overheard messages, and, thus, provide a secure global self-checking network. Unlike traditional Byzantine detection protocols which are receiver-based, this protocol gives the senders an active role in checking the node downstream. This work is inspired by Marti et al.'s watchdogpathrater, which attempts to detect and mitigate the effects of routing misbehavior.
The problem of serving multicast flows in a crossbar switch is considered. Intra-flow linear netw... more The problem of serving multicast flows in a crossbar switch is considered. Intra-flow linear network coding is shown to achieve a larger rate region than the case without coding. A traffic pattern is presented which is achievable with coding but requires a switch speedup when coding is not allowed. The rate region with coding can be characterized in a simple graph-theoretic manner, in terms of the stable set polytope of the "enhanced conflict graph". No such graph-theoretic characterization is known for the case of fanout splitting without coding.
Finally, we extend the ADT networks to those with random erasures and cycles (thus, allowing bi-d... more Finally, we extend the ADT networks to those with random erasures and cycles (thus, allowing bi-directional links). Note that ADT network was proposed for approximating the wireless networks; however, ADT network is acyclic. Furthermore, ADT network does not model the stochastic nature of the wireless links. With our algebraic framework, we incorporate both cycles as well as random failures into ADT network model.
IEEE Journal on Selected Areas in Communications, 2010
Random linear network coding can be used in peerto-peer networks to increase the efficiency of co... more Random linear network coding can be used in peerto-peer networks to increase the efficiency of content distribution and distributed storage. However, these systems are particularly susceptible to Byzantine attacks. We quantify the impact of Byzantine attacks on the coded system by evaluating the probability that a receiver node fails to correctly recover a file. We show that even for a small probability of attack, the system fails with overwhelming probability. We then propose a novel signature scheme that allows packet-level Byzantine detection. This scheme allows one-hop containment of the contamination, and saves bandwidth by allowing nodes to detect and drop the contaminated packets. We compare the net cost of our signature scheme with various other Byzantine schemes, and show that when the probability of Byzantine attacks is high, our scheme is the most bandwidth efficient.
We present a graph theoretic upper bound on speedup needed to achieve 100% throughput in a multic... more We present a graph theoretic upper bound on speedup needed to achieve 100% throughput in a multicast switch using network coding. By bounding speedup, we show the equivalence between network coding and speedup in multicast switches - i.e. network coding, which is usually implemented using software, can in many cases substitute speedup, which is often achieved by adding extra switch fabrics. This bound is based on an approach to network coding problems called the "enhanced conflict graph". We show that the "imperfection ratio" of the enhanced conflict graph gives an upper bound on speedup. In particular, we apply this result to K times N switches with traffic patterns consisting of unicasts and broadcasts only to obtain an upper bound of min(2K-1/K, 2N/N+1).
We consider the problem of serving multicast flows in a crossbar switch. We show that linear netw... more We consider the problem of serving multicast flows in a crossbar switch. We show that linear network coding across packets of a flow can sustain traffic patterns that cannot be served if network coding were not allowed. Thus, network coding leads to a larger rate region in a multicast crossbar switch. We demonstrate a traffic pattern which requires a switch speedup if coding is not allowed, whereas, with coding the speedup requirement is eliminated completely. In addition to throughput benefits, coding simplifies the characterization of the rate region. We give a graph-theoretic characterization of the rate region with fanout splitting and intra-flow coding, in terms of the stable set polytope of the 'enhanced conflict graph' of the traffic pattern. Such a formulation is not known in the case of fanout splitting without coding. We show that computing the offline schedule (i.e. using prior knowledge of the flow arrival rates) can be reduced to certain graph coloring problems. Finally, we propose online algorithms (i.e. using only the current queue occupancy information) for multicast scheduling based on our graph-theoretic formulation. In particular, we show that a maximum weighted stable set algorithm stabilizes the queues for all rates within the rate region.
The problem of serving multicast flows in a crossbar switch is considered. Intraflow linear netwo... more The problem of serving multicast flows in a crossbar switch is considered. Intraflow linear network coding is shown to achieve a larger rate region than the case without coding. A traffic pattern is presented which is achievable with coding but requires a switch speedup when coding is not allowed. The rate region with coding can be characterized in a simple graph-theoretic manner, in terms of the stable set polytope of the "enhanced conflict graph". No such graph-theoretic characterization is known for the case of fanout-splitting without coding. The minimum speedup needed to achieve 100% throughput with coding is shown to be upper bounded by the imperfection ratio of the enhanced conflict graph, where the imperfection ratio measures a certain graph theoretic property of the given graph. When applied to K × N switches with unicasts and broadcasts only, this gives a bound of min(2K-1/K, 2N/N+1) on the speedup. This shows that speedup, which is usually implemented in hardware, can often be substituted by network coding, which can be done in software. Computing an offline schedule (using prior knowledge of the flow rates) is reduced to fractional weighted graph coloring. A graph-theoretic online scheduling algorithm (using only queue occupancy information) is also proposed, that stabilizes the queues for all rates within the rate region.
Multi-resolution codes enable multicast at different rates to different receivers, a setup that i... more Multi-resolution codes enable multicast at different rates to different receivers, a setup that is often desirable for graphics or video streaming. We propose a simple, distributed, two-stage message passing algorithm to generate network codes for single-source multicast of multi-resolution codes. The goal of this pushback algorithm is to maximize the total rate achieved by all receivers, while guaranteeing decodability of the base layer at each receiver. By conducting pushback and code assignment stages, this algorithm takes advantage of inter-layer as well as intra-layer coding. Numerical simulations show that in terms of total rate achieved, the pushback algorithm outperforms routing and intra-layer coding schemes, even with field sizes as small as 2 10 (10 bits). In addition, the performance gap widens as the number of receivers and the number of nodes in the network increases. We also observe that naïve inter-layer coding schemes may perform worse than intra-layer schemes under certain network conditions.
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