2,164 research outputs found
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Unifying Access and Resource Usage Control over Standard Client-Server Interactions
No full textWe 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.Technical report DCS-TR-67
Examining Race/Ethnicity Diversity in the Enrollment of a 4-year CS University Program
No full textComputing departments in the United States are not producing the number of graduates that the workforce needs. At the same time, they lack gender and racial diversity. Therefore, it is important to attract students from minority groups that comprise a significant part of the US population and can bring an enriching, diverse perspective to the development of new technology. In this paper, we study patterns of enrollment and retention among minority students in a 4-year CS university program in order to better understand the challenges for increasing racial and ethnic diversity. We use student data from three core CS classes with a special focus on the introduction to programming (CS1) class. We compare the ethnic makeup of our CS enrollment with that of the student population at our university, that of the state and with nationwide numbers, and examine how the ethnic gap changes from an introductory programming class to an upper level class. We also analyze how different factors such as intent to major, prior experience in computing, and CS1 grades correlate with student retention
Unified Structure and Content Search for Personal Information Management Systems
No full textThe amount of data that users are storing and accessing in personal information systems is growing massively. At the same time, the organization of this data is becoming more heterogeneous, with data spread across different organizational domains such as emails, music databases, and photo albums, some of which are structured by applications rather than users. Powerful search tools are needed to help users locate data in these rapidly expanding yet fragmented data sets. In this paper, we present a novel fuzzy search approach that considers approximate matches to structure and content query conditions. Our approach includes a scoring framework for computing unified relevance scores for potential answers. Critically, our framework uses unified data and query processing models so that structure conditions can be approximately matched by content inside files and vice versa. Our model also unifies external structure (directories) with internal structure (e.g., XML structure), allowing users to specify integrated queries that are matched to a single unified data domain. We propose indexes and algorithms for efficient query processing. Finally, we empirically evaluate our approach using a real data set. We show that our unified fuzzy search approach can leverage structure information to significantly improve search accuracy, yet is robust to mistakes in query conditions.Technical report DCS-TR-66
MassConf: Automatic Configuration Tuning By Leveraging User Community Information
No full textConfiguring modern enterprise software can be extremely difficult, because its behavior often depends on large numbers of configuration parameters. We argue that vendors can simplify the configuration process for new users of their software by collecting and using configuration information from the existing user community. Our proposed approach is based on the observations that (1) a “good” configuration may work well for many different users, and (2) multiple good configurations may work well for each user. We demonstrate our idea by designing MassConf, a system that collects and uses existing configurations to automatically configure new software installations. To evaluate MassConf, we use it to configure the Apache Web server to achieve a response-time target. Our results confirm our observations and show that MassConf successfully reaches the targets of many more new installations than an existing efficient optimization algorithm. Even when we consider only the installations that can be configured with this efficient algorithm, our results show that MassConf reaches the desired targets running many fewer experiments on average.Technical report DCS-TR-66
Abstract 4549: Plasma pharmacokinetics and oral bioavailability of the 3,4,5,6-tetrahydrouridine (THU) prodrug, triacetyl-THU (taTHU), in mice
No full textAbstract
Introduction
Cytidine drugs, such as gemcitabine, undergo rapid, inactivating catabolism by cytidine deaminase (CD). 3,4,5,6-tetrahydrouridine (THU), a potent CD inhibitor, has been applied preclinically and clinically as a modulator of cytidine drug metabolism. However, p.o. THU is at most 20% bioavailable (Beumer et al.), which limits its preclinical evaluation and clinical use. Therefore, the more lipophilic prodrug triacetyl THU (taTHU) was developed. We characterized THU pharmacokinetics after administration of taTHU to mice.
Methods
Mice were dosed 150 mg/kg taTHU i.v. or p.o. Plasma and urine THU concentrations were quantitated with a validated LC-MS/MS assay. Plasma and urine pharmacokinetic parameters and p.o. bioavailability were calculated non-compartmentally and compartmentally. We assessed taTHU inhibition of metabolism of gemcitabine by recombinant CD.
ResultsTHU parameterstaTHU i.v. 150 mg/kgtaTHU p.o. 150 mg/kgCmax (µg/mL)10611.8Tmax (min)560Half-life (min)235122AUC0-inf (mg/mL*min)7.553.36Vd/F (L/kg)4.495.26Cl/F (mL/min/kg)13.229.8F-THUi.v. (%)68.030.3% dose in 0-16 h urine405.6% dose in 0-24 h urine5512
THU, after 150 mg/kg taTHU i.v., had a 235 min terminal half-life and produced plasma THU concentrations >1 µg/mL, the concentration shown to inhibit CD, for 10 h. A multi-compartment model fit the data best. 150 mg/kg p.o. taTHU produced a concentration versus time profile with a plateau of approximately 10 µg/mL from 0.5-2 h, followed by a decline with a 122 min half-life. Approximately 68% of i.v. taTHU was converted to THU. Approximately 30% of p.o. taTHU reached the systemic circulation as THU. After i.v dosing, renal excretion accounted for 40-55% of the taTHU dose, 26-35% as THU and an additional 14-19% as acetylated forms of THU. After p.o. dosing, the renal excretion percentages were 6-12%, 5.2-11%, and 0.42-0.71%, respectively. taTHU did not inhibit recombinant CD.
Conclusion
The availability of THU after p.o. taTHU in mice is 30%, as compared to the 20% achieved after p.o. THU. Clinical studies are warranted to evaluate availability of THU from taTHU in humans.
Support: N01-CM07106, N01-CM52202, P30-CA47904 from the NCI and P41-EB001978.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4549.</jats:p
Factors Affecting Customer Purchase Decision on Organic Vegetables in Yangon (Min Thu Han, 2023)
No full textThe purposes of this study are to analyze the influencing factors on purchase
behavior for organic vegetables of consumers and to examine the effect of purchase
decision on repurchase intention on organic vegetables purchase in Yangon area. Primary
data are collected from 73 consumers who were purchasing vegetables at supermarket,
organic stores and farm in Yangon with structured questionnaire described with 5-point
Likert scale by applying sample random sampling method. In descriptive method, this
study found that majority of customer have highest level of agreement on customer
attributes towards purchase decision of organic vegetables. The study shows that
subjective norm and perceived behavior control have significant effect on purchase
decision of consumer of organic vegetables. The results also indicate that consumer
purchase decision has positive effect on repurchase intention of consumers on organic
vegetables. Thus, this study strongly recommends organic vegetables producers and
marketer to provide good service and offering trading fresh organic vegetables
Employee Commitment and Employee Performance In Nay Kyel Oo Construction., LTD. (Ya Min Thu, 2019)
No full textThis research aims to identify the influencing Human Resource Management practices on organizational commitment and to analyze the effects of organizational commitment on employee performance in Nay Kyel Oo Construction Co., Ltd. The data are collected with structured questionnaires from 130 employees working in Nay Kyel Oo Construction Co., Ltd. Among the four HRM practices, training, and development, performance appraisal, rewards and benefits practices are found positive significant effect on affective commitment. All HRM practices have a positive impact on continuance and normative commitment. Moreover, affective commitment and continuance commitment has a strong influence on employee performance. The study recommends that in order to improve the organizational commitment and employee performance, management should create clear and realistic job descriptions, management should design rewards system linked to performance levels and the supervisors should encourage the participation of employees in training programs
Quantifying and Improving I/O Predictability in Virtualized Systems
No full textVirtualization enables the consolidation of virtual machines (VMs) to increase the utilization of physical servers in Infrastructure-as-a-Service (IaaS) cloud providers. Unfortunately, our quantification of storage I/O performance across a range of workloads, virtual machine monitor (VMM) architectures, approaches to storage virtualization, and storage devices shows widespread performance unpredictability in the face of consolidation. Surprisingly, the use of solid-state drives (SSDs) can exacerbate the problem. Since many users may desire consistent performance, we argue that IaaS cloud providers should provide a class of predictable-performance service in addition to their existing (predictability-oblivious) services. Thus, we propose and evaluate VirtualFence, a storage system that provides predictable performance for this new class of service. VirtualFence uses three main techniques: (1) non-work-conserving time-division I/O scheduling, (2) a small SSD cache in front of a much larger hard disk drive (HDD), and (3) space-partitioning of both the SSD cache and the HDD. Our evaluation of a prototype VirtualFence implemented in the Xen VMM shows that VirtualFence improves predictability significantly. More fundamentally, our evaluation illustrates the tradeoff between predictability and performance. We conclude that current VMMs are far from providing predictability. Systems like VirtualFence can remedy this problem, while allowing the cloud provider to select an appropriate compromise between performance and predictability.Technical report DCS-TR-69
Efficient Multi-Dimensional Query Processing in Personal Information Management Systems
No full textThe relentless growth in capacity and dropping price of storage are driving an explosion in the amount of information users are collecting and storing in personal information management systems. This explosion of information has led to a critical need for complex search tools to access often very heterogeneous data in asimple and efficient manner. Such tools should provide both high-quality flexible scoring mechanisms and efficient query processing capabilities. In this paper, we focus on indexes and algorithms to efficiently identify the most relevant files that match multi-dimensional queries comprised of relaxed content, metadata, and structure conditions. We also adapted existing top-k query strategies to our specific scenario. Our work is integrated in Wayfinder, an existing fully functioning file system. We perform a thorough experimental evaluation of our file search techniques and show that our query processing strategies exhibit good behavior across all dimensions, resulting in good overall query performance and good scalability.Technical report DCS-TR-62
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