In recognition of the high rates of undetected tuberculosis in the community, the World Health Or... more In recognition of the high rates of undetected tuberculosis in the community, the World Health Organization (WHO) encourages targeted active case finding (ACF) among “high-risk” populations. While this strategy has led to increased case detection in these populations, the epidemic impact of these interventions has not been demonstrated. Historical data suggest that population-wide (untargeted) ACF can interrupt transmission in high-incidence settings, but implementation remains lacking, despite recent advances in screening tools. The reservoir of latent infection—affecting up to a quarter of the global population –complicates elimination efforts by acting as a pool from which future tuberculosis cases may emerge, even after all active cases have been treated. A holistic case finding strategy that addresses both active disease and latent infection is likely to be the optimal approach for rapidly achieving sustainable progress toward TB elimination in a durable way, but safety and cos...
Demand for clean products and services is increasing as society is becoming increasingly aware of... more Demand for clean products and services is increasing as society is becoming increasingly aware of climate change. In response, many enterprises are setting explicit sustainability goals and implementing initiatives to reduce carbon emissions. Quantification and disclosure of such goals and initiatives have become important marketing tools. As enterprises and individuals shift their workloads to the cloud, this drive toward quantification and disclosure will lead to demand for quantifiable green cloud services. Thus, we argue that cloud providers should offer a new class of green services, in addition to existing (energy-sourceoblivious) services. This new class would provide clients with explicit service-level agreements (which we call Green SLAs) for the percentage of renewable energy used to run their workloads. In this paper, we first propose an approach for High Performance Computing cloud providers to offer such a Green SLA service. Specifically, each client job specifies a Green SLA, which is the minimum percentage of green energy that must be used to run the job. The provider earns a premium for meeting the Green SLA, but is penalized if it accepts the job but violates the Green SLA. We then propose (1) a power distribution and control infrastructure that uses a small amount of hardware to support Green SLAs, (2) an optimization-based framework for scheduling jobs and power sources that maximizes provider profits while respecting Green SLAs, and (3) two scheduling policies based on the framework. We evaluate our framework and policies extensively through simulations. Our main results show the tradeoffs between our policies, and their advantages over simpler greedy heuristics. We conclude that a Green SLA service that uses our policies would enable the provider to attract environmentally conscious clients, especially those who require strict guarantees on their use of green energy.
We consider the problem of increasing the availability of shared data in peer-to-peer systems. In... more We consider the problem of increasing the availability of shared data in peer-to-peer systems. In particular, we conservatively estimate the amount of excess storage required to achieve a practical availability of 99.9% by studying a decentralized algorithm that only depends on a modest amount of loosely synchronized global state. Our algorithm uses randomized decisions extensively together with a novel application of an erasure code to tolerate autonomous peer actions as well as staleness in the loosely synchronized global state. We study the behavior of this algorithm in three distinct environments modeled on previously reported measurements. We show that while peers act autonomously, the community as a whole will reach a stable configuration. We also show that space is used fairly and efficiently, delivering three nines availability at a cost of six times the storage footprint of the data collection when the average peer availability is only 24%.
protocols. This metric stands in contrast to most existing range control works, which try to mini... more protocols. This metric stands in contrast to most existing range control works, which try to minimize energy consumption [4], maintain network connectivity [1, 5] or maximize spatial reuse in terms of unicast traffic [3].
Supported MOx (M= Mo, V) on mixed CeO2-TiO2 were investigated for the oxidative dehydrogenation o... more Supported MOx (M= Mo, V) on mixed CeO2-TiO2 were investigated for the oxidative dehydrogenation of ethane (ODHE) using CO2 as a mild oxidant. Raman spectroscopic characterization of the synthesized catalysts under dehydrated conditions suggest that surface MoOx species prefer to anchor on the crystalline domains of TiO2. Upon increasing the amount of CeO2 in the mixed oxide support, an intense and broad band at ~930cm-1 underscored that the prevalent species tend to be polymeric (MoOx)n domains. On the other hand, in the case of VOx catalysts, a gradual shift in the symmetric stretching of the vanadyl (V=O) Raman band with increasing CeO2 content was observed that points at the gradual anchoring of the surface vanadia
With the number of Computer Science (CS) jobs on the rise, there is a greater need for Computer S... more With the number of Computer Science (CS) jobs on the rise, there is a greater need for Computer Science graduates than ever. At the same time, most CS departments across the country are only seeing 25-30% of female students in their classes, meaning that we are failing to draw interest from a large portion of the population. In this work, we explore the gender gap in CS at a large public research university, using three data sets that span thousands of students across 5.5 academic years. By combining these data sets, we can explore many issues such as retention as students progress through the CS major. For example, we nd that a large percentage of women taking the Introductory CS1 course for majors do not intend to major in CS, which contributes to a large increase in the gender gap immediately a er CS1. is nding implies that a large part of the retention task is a racting these women to further explore the major. We report ndings in three areas of research in the context of the CS department at our university: the CS environment, the computing background of our students, and the students' grades. ese ndings may also be applicable to computing programs at other large public research universities.
Preeclampsia is one of the most serious complications of pregnancy. Currently there are no medica... more Preeclampsia is one of the most serious complications of pregnancy. Currently there are no medical treatments. Given placental oxidative stress may be an early trigger in the pathogenesis of preeclampsia, therapies that enhance antioxidant pathways have been proposed as treatments. Melatonin is a direct free-radical scavenger and indirect antioxidant. We performed in vitro assays to assess whether melatonin 1) enhances the antioxidant response element genes (heme-oxygenase 1, (HO-1), glutamate-cysteine ligase (GCLC), NAD(P)H: quinone acceptor oxidoreductase 1 (NQO1), thioredoxin (TXN)) or 2) alters secretion of the anti-angiogenic factors soluble fms-like tyrosine kinase-1 (sFLT) or soluble endoglin (sENG) from human primary trophoblasts, placental explants and human umbilical vein endothelial cells (HUVECs) and 3) can rescue TNF-α induced endothelial dysfunction. In primary trophoblast melatonin treatment increased expression of the antioxidant enzyme TXN. Expression of TXN, GCLC and NQO1 was upregulated in placental tissue with melatonin treatment. HUVECs treated with melatonin showed an increase in both TXN and GCLC. Melatonin did not increase HO-1 expression in any of the tissues examined. Melatonin reduced sFLT secretion from primary trophoblasts, but had no effect on sFLT or sENG secretion from placental explants or HUVECs. Melatonin did not rescue TNF-α induced VCAM-1 and ET-1 expression in endothelial cells. Our findings suggest that melatonin induces antioxidant pathways in placenta and endothelial cells. Furthermore, it may have effects in reducing sFLT secretion from trophoblast, but does not reduce endothelial dysfunction. Given it is likely to be safe in pregnancy, it may have potential as a therapeutic agent to treat or prevent preeclampsia.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The kinetic behavior of CrOx sites supported on Fe doped CeO2 was studied for CO2-assisted propan... more The kinetic behavior of CrOx sites supported on Fe doped CeO2 was studied for CO2-assisted propane oxidative dehydrogenation.
In recent years, extracellular vesicles (EVs) secreted by mesenchymal stem cells (MSCs) have emer... more In recent years, extracellular vesicles (EVs) secreted by mesenchymal stem cells (MSCs) have emerged as a potential cell-free therapy against osteoarthritis (OA). Thus, we investigated the therapeutic effects of EVs released by cytokineprimed umbilical cord-derived MSCs (UCMSCs) on osteoarthritic chondrocyte physiology. Priming UCMSCs individually with transforming growth factor beta (TGFb), interferon alpha (IFNa), or tumor necrosis factor alpha (TNFa) significantly reduced the sorting of miR-181b-3p but not miR-320a-3p; two negative regulators of chondrocyte regeneration, into EVs. However, the EV treatment did not show any significant effect on chondrocyte proliferation. Meanwhile, EVs from both non-priming and cytokine-primed UCMSCs induced migration at later time points of measurement. Moreover, TGFbprimed UCMSCs secreted EVs that could upregulate the expression of chondrogenesis markers (COL2 and ACAN) and downregulate fibrotic markers (COL1 and RUNX2) in chondrocytes. Hence, priming UCMSCs with cytokines can deliver selective therapeutic effects of EV treatment in OA and chondrocyte-related disorders.
Substituted quinolines (PQ code number), which reduce colony formation and increase gap junctiona... more Substituted quinolines (PQ code number), which reduce colony formation and increase gap junctional intercellular communication, were tested for their ability to interact with various molecular targets in murine and human tumor cell lines in vitro. Various markers of tumor cell metabolism, DNA fragmentation, mitotic disruption, apoptosis induction and growth factor receptor signaling pathways were assayed in vitro to evaluate drug cytotoxicity. Based on its ability to inhibit the metabolic activity of suspension cultures of leukemic L1210 cells at days 2 and 4 in vitro, PQ1 succinic acid salt is the most effective antiproliferative agent among the synthetic quinoline analogs tested. Moreover, antiproliferative PQ1 is effective across a spectrum of monolayer cultures of pancreatic Pan02, epidermoid A-431 and mammary SK-BR-3 and BT-474 tumor cells. PQ1 also blocks Ki-67 expression, a marker of tumor cell proliferation. A 1.5-to 3-h treatment with PQ1 is sufficient to inhibit the incorporations of [ 3 H]thymidine into DNA, [ 3 H]-uridine into RNA and [ 3 H]-leucine into protein used to assess the rates of macromolecule syntheses over a 0.5-or 1-h period of pulse-labeling in L1210 tumor cells. A 15-min pretreatment with PQ1 inhibits the cellular transport of both purine and pyrimidine nucleosides over a 30-sec period in vitro, suggesting that PQ1 may prevent the incorporation of [ 3 H]-adenosine and [ 3 H]-thymidine into DNA because it rapidly blocks the uptake of these nucleosides by the tumor cells. Since PQ1 does not reduce the fluorescence of the ethidium bromide-DNA complex, it does not directly bind to or destabilize double-stranded DNA. Over a 6-to-48-h period, PQ1 has very little effect on the mitotic index of L1210 cells but stimulates the formation of many binucleated cells and a few micronuclei, suggesting that this compound might increase mitotic abnormality, induce chromosomal damage or missegregation, and block cytokinesis. The fact that PQ1 induces initiator caspase-2 and effector caspase-3 activities and poly(ADP-ribose) polymerase-1 cleavage within 1-4 h and internucleosomal DNA fragmentation within 24 h in L1210 cells suggests that this antitumor drug can trigger the early and late events required for cells to undergo apotosis. Whole-cell immunodetection and Western blot analysis indicate that, in contrast to 17-(allylamino)-17-demethoxygeldanamycin and radicicol, PQ1 fails to down-regulate the protein level at 24 h and autophosphorylation at 3 h of membrane-anchored HER1 in A-431 cells and HER2 in SK-BR-3 cells, suggesting that this antitumor compound is unlikely to interact with and inhibit Hsp90 and the epidermal growth factor (EGF) receptor signaling pathways. In conclusion, antiproliferative PQ1 is effective against a spectrum of tumor cells and might interact with various membrane and nuclear targets to enhance gap junctions, inhibit nucleoside transport and block cytokinesis but does not appear to disrupt the EGF receptor-mediated signaling pathways to induce growth arrest and apoptosis.
We propose a novel framework for integrated access and resource usage control over standard clien... more We propose a novel framework for integrated access and resource usage control over standard clientserver interactions. Historically, access control has been developed without considering resource usage. Resource control has thus developed as an ad hoc server-centric set of mechanisms (e.g., file system quota, network bandwidth quote, etc.). We believe that resource usage control is strongly related to access control and so should be implemented using a unified, global enforcement framework. We introduce such a framework, where services have resource usage constraints and principals have resource usage histories. To access and use a service, a principal must have the appropriate access and sufficient resource usage rights when considering its usage history. Our framework is able to enforce global stateful policies, yet do not require changes to existing message-passing applications. We have built a prototype and used it to specify and enforce an example policy that includes role-based control and delegation. We applied our system to control access and resource usage for three different services, network, DNS, and SMB file systems, to demonstrate its effectiveness and wide applicability.
The decreasing costs of computing devices, increases in connectivity, and improved performance ar... more The decreasing costs of computing devices, increases in connectivity, and improved performance are altering the computing environments of users in fundamental ways. Users are no longer restricted to operating single devices in isolation but rather distribute and access information across many devices and develop complex sharing patterns among groups of users. Unfortunately, while these trends are significantly enriching the user's computing experience, they are also increasing the data management overhead as users must explicitly reason about data placement and replication across multiple devices and logical sharing groups. In this thesis, we present the Wayfinder file system, which was designed to simplify the management of information in federate systems. Wayfinder focuses on three critical management deficiencies present in most current federated environments: 1) the lack of a consistent view for stored information across devices, 2) the required manual management of replicated information, and 3) the limited search/ranking capability for finding relevant information. The Wayfinder file system addresses these deficiencies by providing three synergistic abstractions: 1) a global namespace that is uniformly accessible across connected and disconnected operation, 2) a user-centric automatic availability management to ensure
Configuring modern enterprise software can be extremely difficult because their behaviors often d... more Configuring modern enterprise software can be extremely difficult because their behaviors often depend on large numbers of configuration parameters. Software vendors can simplify the configuration process for new users by collecting and using configuration information from existing users. In particular, we observe that (1) a "good" configuration may work well for many different users, and (2) multiple configurations may work well for each user. We leverage these observations to design MassConf, a system that collects and uses existing configurations to automatically configure new software installations. Our evaluations with a case study confirm our observations and show that MassConf successfully reaches the targets of many more new installations than an existing efficient optimization algorithm.
In recognition of the high rates of undetected tuberculosis in the community, the World Health Or... more In recognition of the high rates of undetected tuberculosis in the community, the World Health Organization (WHO) encourages targeted active case finding (ACF) among “high-risk” populations. While this strategy has led to increased case detection in these populations, the epidemic impact of these interventions has not been demonstrated. Historical data suggest that population-wide (untargeted) ACF can interrupt transmission in high-incidence settings, but implementation remains lacking, despite recent advances in screening tools. The reservoir of latent infection—affecting up to a quarter of the global population –complicates elimination efforts by acting as a pool from which future tuberculosis cases may emerge, even after all active cases have been treated. A holistic case finding strategy that addresses both active disease and latent infection is likely to be the optimal approach for rapidly achieving sustainable progress toward TB elimination in a durable way, but safety and cos...
Demand for clean products and services is increasing as society is becoming increasingly aware of... more Demand for clean products and services is increasing as society is becoming increasingly aware of climate change. In response, many enterprises are setting explicit sustainability goals and implementing initiatives to reduce carbon emissions. Quantification and disclosure of such goals and initiatives have become important marketing tools. As enterprises and individuals shift their workloads to the cloud, this drive toward quantification and disclosure will lead to demand for quantifiable green cloud services. Thus, we argue that cloud providers should offer a new class of green services, in addition to existing (energy-sourceoblivious) services. This new class would provide clients with explicit service-level agreements (which we call Green SLAs) for the percentage of renewable energy used to run their workloads. In this paper, we first propose an approach for High Performance Computing cloud providers to offer such a Green SLA service. Specifically, each client job specifies a Green SLA, which is the minimum percentage of green energy that must be used to run the job. The provider earns a premium for meeting the Green SLA, but is penalized if it accepts the job but violates the Green SLA. We then propose (1) a power distribution and control infrastructure that uses a small amount of hardware to support Green SLAs, (2) an optimization-based framework for scheduling jobs and power sources that maximizes provider profits while respecting Green SLAs, and (3) two scheduling policies based on the framework. We evaluate our framework and policies extensively through simulations. Our main results show the tradeoffs between our policies, and their advantages over simpler greedy heuristics. We conclude that a Green SLA service that uses our policies would enable the provider to attract environmentally conscious clients, especially those who require strict guarantees on their use of green energy.
We consider the problem of increasing the availability of shared data in peer-to-peer systems. In... more We consider the problem of increasing the availability of shared data in peer-to-peer systems. In particular, we conservatively estimate the amount of excess storage required to achieve a practical availability of 99.9% by studying a decentralized algorithm that only depends on a modest amount of loosely synchronized global state. Our algorithm uses randomized decisions extensively together with a novel application of an erasure code to tolerate autonomous peer actions as well as staleness in the loosely synchronized global state. We study the behavior of this algorithm in three distinct environments modeled on previously reported measurements. We show that while peers act autonomously, the community as a whole will reach a stable configuration. We also show that space is used fairly and efficiently, delivering three nines availability at a cost of six times the storage footprint of the data collection when the average peer availability is only 24%.
protocols. This metric stands in contrast to most existing range control works, which try to mini... more protocols. This metric stands in contrast to most existing range control works, which try to minimize energy consumption [4], maintain network connectivity [1, 5] or maximize spatial reuse in terms of unicast traffic [3].
Supported MOx (M= Mo, V) on mixed CeO2-TiO2 were investigated for the oxidative dehydrogenation o... more Supported MOx (M= Mo, V) on mixed CeO2-TiO2 were investigated for the oxidative dehydrogenation of ethane (ODHE) using CO2 as a mild oxidant. Raman spectroscopic characterization of the synthesized catalysts under dehydrated conditions suggest that surface MoOx species prefer to anchor on the crystalline domains of TiO2. Upon increasing the amount of CeO2 in the mixed oxide support, an intense and broad band at ~930cm-1 underscored that the prevalent species tend to be polymeric (MoOx)n domains. On the other hand, in the case of VOx catalysts, a gradual shift in the symmetric stretching of the vanadyl (V=O) Raman band with increasing CeO2 content was observed that points at the gradual anchoring of the surface vanadia
With the number of Computer Science (CS) jobs on the rise, there is a greater need for Computer S... more With the number of Computer Science (CS) jobs on the rise, there is a greater need for Computer Science graduates than ever. At the same time, most CS departments across the country are only seeing 25-30% of female students in their classes, meaning that we are failing to draw interest from a large portion of the population. In this work, we explore the gender gap in CS at a large public research university, using three data sets that span thousands of students across 5.5 academic years. By combining these data sets, we can explore many issues such as retention as students progress through the CS major. For example, we nd that a large percentage of women taking the Introductory CS1 course for majors do not intend to major in CS, which contributes to a large increase in the gender gap immediately a er CS1. is nding implies that a large part of the retention task is a racting these women to further explore the major. We report ndings in three areas of research in the context of the CS department at our university: the CS environment, the computing background of our students, and the students' grades. ese ndings may also be applicable to computing programs at other large public research universities.
Preeclampsia is one of the most serious complications of pregnancy. Currently there are no medica... more Preeclampsia is one of the most serious complications of pregnancy. Currently there are no medical treatments. Given placental oxidative stress may be an early trigger in the pathogenesis of preeclampsia, therapies that enhance antioxidant pathways have been proposed as treatments. Melatonin is a direct free-radical scavenger and indirect antioxidant. We performed in vitro assays to assess whether melatonin 1) enhances the antioxidant response element genes (heme-oxygenase 1, (HO-1), glutamate-cysteine ligase (GCLC), NAD(P)H: quinone acceptor oxidoreductase 1 (NQO1), thioredoxin (TXN)) or 2) alters secretion of the anti-angiogenic factors soluble fms-like tyrosine kinase-1 (sFLT) or soluble endoglin (sENG) from human primary trophoblasts, placental explants and human umbilical vein endothelial cells (HUVECs) and 3) can rescue TNF-α induced endothelial dysfunction. In primary trophoblast melatonin treatment increased expression of the antioxidant enzyme TXN. Expression of TXN, GCLC and NQO1 was upregulated in placental tissue with melatonin treatment. HUVECs treated with melatonin showed an increase in both TXN and GCLC. Melatonin did not increase HO-1 expression in any of the tissues examined. Melatonin reduced sFLT secretion from primary trophoblasts, but had no effect on sFLT or sENG secretion from placental explants or HUVECs. Melatonin did not rescue TNF-α induced VCAM-1 and ET-1 expression in endothelial cells. Our findings suggest that melatonin induces antioxidant pathways in placenta and endothelial cells. Furthermore, it may have effects in reducing sFLT secretion from trophoblast, but does not reduce endothelial dysfunction. Given it is likely to be safe in pregnancy, it may have potential as a therapeutic agent to treat or prevent preeclampsia.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The kinetic behavior of CrOx sites supported on Fe doped CeO2 was studied for CO2-assisted propan... more The kinetic behavior of CrOx sites supported on Fe doped CeO2 was studied for CO2-assisted propane oxidative dehydrogenation.
In recent years, extracellular vesicles (EVs) secreted by mesenchymal stem cells (MSCs) have emer... more In recent years, extracellular vesicles (EVs) secreted by mesenchymal stem cells (MSCs) have emerged as a potential cell-free therapy against osteoarthritis (OA). Thus, we investigated the therapeutic effects of EVs released by cytokineprimed umbilical cord-derived MSCs (UCMSCs) on osteoarthritic chondrocyte physiology. Priming UCMSCs individually with transforming growth factor beta (TGFb), interferon alpha (IFNa), or tumor necrosis factor alpha (TNFa) significantly reduced the sorting of miR-181b-3p but not miR-320a-3p; two negative regulators of chondrocyte regeneration, into EVs. However, the EV treatment did not show any significant effect on chondrocyte proliferation. Meanwhile, EVs from both non-priming and cytokine-primed UCMSCs induced migration at later time points of measurement. Moreover, TGFbprimed UCMSCs secreted EVs that could upregulate the expression of chondrogenesis markers (COL2 and ACAN) and downregulate fibrotic markers (COL1 and RUNX2) in chondrocytes. Hence, priming UCMSCs with cytokines can deliver selective therapeutic effects of EV treatment in OA and chondrocyte-related disorders.
Substituted quinolines (PQ code number), which reduce colony formation and increase gap junctiona... more Substituted quinolines (PQ code number), which reduce colony formation and increase gap junctional intercellular communication, were tested for their ability to interact with various molecular targets in murine and human tumor cell lines in vitro. Various markers of tumor cell metabolism, DNA fragmentation, mitotic disruption, apoptosis induction and growth factor receptor signaling pathways were assayed in vitro to evaluate drug cytotoxicity. Based on its ability to inhibit the metabolic activity of suspension cultures of leukemic L1210 cells at days 2 and 4 in vitro, PQ1 succinic acid salt is the most effective antiproliferative agent among the synthetic quinoline analogs tested. Moreover, antiproliferative PQ1 is effective across a spectrum of monolayer cultures of pancreatic Pan02, epidermoid A-431 and mammary SK-BR-3 and BT-474 tumor cells. PQ1 also blocks Ki-67 expression, a marker of tumor cell proliferation. A 1.5-to 3-h treatment with PQ1 is sufficient to inhibit the incorporations of [ 3 H]thymidine into DNA, [ 3 H]-uridine into RNA and [ 3 H]-leucine into protein used to assess the rates of macromolecule syntheses over a 0.5-or 1-h period of pulse-labeling in L1210 tumor cells. A 15-min pretreatment with PQ1 inhibits the cellular transport of both purine and pyrimidine nucleosides over a 30-sec period in vitro, suggesting that PQ1 may prevent the incorporation of [ 3 H]-adenosine and [ 3 H]-thymidine into DNA because it rapidly blocks the uptake of these nucleosides by the tumor cells. Since PQ1 does not reduce the fluorescence of the ethidium bromide-DNA complex, it does not directly bind to or destabilize double-stranded DNA. Over a 6-to-48-h period, PQ1 has very little effect on the mitotic index of L1210 cells but stimulates the formation of many binucleated cells and a few micronuclei, suggesting that this compound might increase mitotic abnormality, induce chromosomal damage or missegregation, and block cytokinesis. The fact that PQ1 induces initiator caspase-2 and effector caspase-3 activities and poly(ADP-ribose) polymerase-1 cleavage within 1-4 h and internucleosomal DNA fragmentation within 24 h in L1210 cells suggests that this antitumor drug can trigger the early and late events required for cells to undergo apotosis. Whole-cell immunodetection and Western blot analysis indicate that, in contrast to 17-(allylamino)-17-demethoxygeldanamycin and radicicol, PQ1 fails to down-regulate the protein level at 24 h and autophosphorylation at 3 h of membrane-anchored HER1 in A-431 cells and HER2 in SK-BR-3 cells, suggesting that this antitumor compound is unlikely to interact with and inhibit Hsp90 and the epidermal growth factor (EGF) receptor signaling pathways. In conclusion, antiproliferative PQ1 is effective against a spectrum of tumor cells and might interact with various membrane and nuclear targets to enhance gap junctions, inhibit nucleoside transport and block cytokinesis but does not appear to disrupt the EGF receptor-mediated signaling pathways to induce growth arrest and apoptosis.
We propose a novel framework for integrated access and resource usage control over standard clien... more We propose a novel framework for integrated access and resource usage control over standard clientserver interactions. Historically, access control has been developed without considering resource usage. Resource control has thus developed as an ad hoc server-centric set of mechanisms (e.g., file system quota, network bandwidth quote, etc.). We believe that resource usage control is strongly related to access control and so should be implemented using a unified, global enforcement framework. We introduce such a framework, where services have resource usage constraints and principals have resource usage histories. To access and use a service, a principal must have the appropriate access and sufficient resource usage rights when considering its usage history. Our framework is able to enforce global stateful policies, yet do not require changes to existing message-passing applications. We have built a prototype and used it to specify and enforce an example policy that includes role-based control and delegation. We applied our system to control access and resource usage for three different services, network, DNS, and SMB file systems, to demonstrate its effectiveness and wide applicability.
The decreasing costs of computing devices, increases in connectivity, and improved performance ar... more The decreasing costs of computing devices, increases in connectivity, and improved performance are altering the computing environments of users in fundamental ways. Users are no longer restricted to operating single devices in isolation but rather distribute and access information across many devices and develop complex sharing patterns among groups of users. Unfortunately, while these trends are significantly enriching the user's computing experience, they are also increasing the data management overhead as users must explicitly reason about data placement and replication across multiple devices and logical sharing groups. In this thesis, we present the Wayfinder file system, which was designed to simplify the management of information in federate systems. Wayfinder focuses on three critical management deficiencies present in most current federated environments: 1) the lack of a consistent view for stored information across devices, 2) the required manual management of replicated information, and 3) the limited search/ranking capability for finding relevant information. The Wayfinder file system addresses these deficiencies by providing three synergistic abstractions: 1) a global namespace that is uniformly accessible across connected and disconnected operation, 2) a user-centric automatic availability management to ensure
Configuring modern enterprise software can be extremely difficult because their behaviors often d... more Configuring modern enterprise software can be extremely difficult because their behaviors often depend on large numbers of configuration parameters. Software vendors can simplify the configuration process for new users by collecting and using configuration information from existing users. In particular, we observe that (1) a "good" configuration may work well for many different users, and (2) multiple configurations may work well for each user. We leverage these observations to design MassConf, a system that collects and uses existing configurations to automatically configure new software installations. Our evaluations with a case study confirm our observations and show that MassConf successfully reaches the targets of many more new installations than an existing efficient optimization algorithm.
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