150 research outputs found

    Does It Pay To Attend An Elite Private College? Cross Cohort Evidence on the Effects of College Quality on Earnings

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    While there is evidence of a substantial and rising labor market premium associated with college attendance, little is known about how this premium varies across institutions of different quality and across time. Previous research which has estimated the return to college quality has not taken into account that individuals likely select the type of college they attend based in part on the expected economic return and net costs. In this paper we explicitly model high school students' choice of college type (characterized by quality and control) based on individual and family characteristics (including ability and parental economic status), and an estimate of the net costs of attendance and expected labor market return. We estimate selectivity corrected outcome equations, using data from both the National Longitudinal Study of the High School Class of 1972 and High School and Beyond, which permit us to determine the effects of college quality on wages and earnings and how this effect varies across time. Even after controlling for selection effects there is strong evidence of significant economic return to attending an elite private institution, and some evidence that this premium has increased over time.

    Dynamic CPU management for real-time, middleware-based systems

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    Journal ArticleMany real-world distributed, real-time, embedded (DRE) systems, such as multi-agent military applications, are built using commercially available operating systems, middleware, and collections of pre-existing software. The complexity of these systems makes it difficult to ensure that they maintain high quality of service (QOS). At design time, the challenge is to introduce coordinated QOS controls into multiple software elements in a non-invasive manner. At run time, the system must adapt dynamically to maintain high QOS in the face of both expected events, such as application mode changes, and unexpected events, such as resource demands from other applications. In this paper we describe the design and implementation of a CPU Broker for these types of DRE systems. The CPU Broker mediates between multiple real-time tasks and the facilities of a real-time operating system: using feedback and other inputs, it adjusts allocations over time to ensure that high application-level QOS is maintained. The broker connects to its monitored tasks in a non-invasive manner, is based on and integrated with industry-standard middleware, and implements an open architecture for new CPU management policies. Moreover, these features allow the broker to be easily combined with other QOS mechanisms and policies, as part of an overall end-to-end QOS management system. We describe our experience in applying the CPU Broker to a simulated DRE military system. Our results show that the broker connects to the system transparently and allows it to function in the face of run-time CPU resource contention

    Benchmarks can make sense

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    Integrated scientific workflow management for the Emulab network testbed

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    Journal ArticleThe main forces that shaped current network testbeds were the needs for realism and scale. Now that several testbeds support large and complex experiments, management of experimentation processes and results has become more difficult and a barrier to high-quality systems research. The popularity of network testbeds means that new tools for managing experiment workflows, addressing the ready-made base of testbed users, can have important and significant impacts. We are now evolving Emulab, our large and popular network testbed, to support experiments that are organized around scientific workflows. This paper summarizes the opportunities in this area, the new approaches we are taking, our implementation in progress, and the challenges in adapting scientific workflow concepts for testbed-based research. With our system, we expect to demonstrate that a network testbed with integrated scientific workflow management can be an important tool to aid research in networking and distributed systems

    Static and dynamic structure in design patterns

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    technical reportDesign patterns are a valuable mechanism for emphasizing structure, capturing design expertise, and facilitating restructuring of software systems. Patterns are typically applied in the context of an object-oriented language and are implemented so that the pattern participants correspond to object instances that are created and connected at run-time. This paper describes a complementary realization of design patterns, in which the pattern participants are statically instantiated and connected components. Our approach separates the static parts of the software design from the dynamic parts of the system behavior. This separation makes the software design more amenable to analysis, enabling more effective and domain specific detection of system design errors, prediction of run-time behavior, and more effective optimization. This technique is applicable to imperative, functional, and object-oriented languages: we have extended C, Scheme, and Java with our component model. In this paper, we illustrate this approach in the context of the OSKit, a collection of operating system components written in C

    Dynamic CPU management for real-time, middleware-based systems

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    technical reportMany real-world distributed, real-time, embedded (DRE) systems, such as multi-agent military applications, are built using commercially available operating systems, middleware, and collections of pre-existing software. The complexity of these systems makes it difficult to ensure that they maintain high quality of service (QoS). At design time, the challenge is to introduce coordinated QoS controls into multiple software elements in a non-invasive manner. At run time, the system must adapt dynamically to maintain high QoS in the face of both expected events, such as application mode changes, and unexpected events, such as resource demands from other applications. In this paper we describe the design and implementation of a CPU Broker for these types of DRE systems. The CPU Broker mediates between multiple real-time tasks and the facilities of a real-time operating system: using feedback and other inputs, it adjusts allocations over time to ensure that high application-level QoS is maintained. The broker connects to its monitored tasks in a non-invasive manner, is based on and integrated with industry-standard middleware, and implements an open architecture for new CPU management policies. Moreover, these features allow the broker to be easily combined with other QoS mechanisms and policies, as part of an overall end-to-end QoS management system. We describe our experience in applying the CPU Broker to a simulated DRE military system. Our results show that the broker connects to the system transparently and allows it to function in the face of run-time CPU resource contention

    Do Bans on Affirmative Action Hurt Minority Students? Evidence from the Texas Top 10% Plan

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    Standard-Nutzungsbedingungen: Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden. Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. www.econstor.eu The Institute for the Study of Labor (IZA) in Bonn is a local and virtual international research center and a place of communication between science, politics and business. IZA is an independent nonprofit organization supported by Deutsche Post Foundation. The center is associated with the University of Bonn and offers a stimulating research environment through its international network, workshops and conferences, data service, project support, research visits and doctoral program. IZA engages in (i) original and internationally competitive research in all fields of labor economics, (ii) development of policy concepts, and (iii) dissemination of research results and concepts to the interested public. Terms of use: Documents in D I S C U S S I O N P A P E R S E R I E S IZA Discussion Papers often represent preliminary work and are circulated to encourage discussion. Citation of such a paper should account for its provisional character. A revised version may be available directly from the author. In light of the recent bans on affirmative action in higher education, this paper provides new evidence on the effects of alternative admissions policies on the persistence and college completion of minority students. I find that the change from affirmative action to the Top 10% Plan in Texas decreased both retention and graduation rates of lower-ranked minority students. Results show that both fall-to-fall freshmen retention and six-year college graduation of second-decile minority students decreased, respectively, by 2.4 and 3.3 percentage points. The effect of the change in admissions policy was slightly larger for minority students in the third and lower deciles: fall-to-fall freshmen retention and six-year college graduation decreased, respectively, by 4.9 and 4.2 percentage points. Moreover, I find no evidence in support of the minority "mismatch" hypothesis. These results suggest that most of the increase in the graduation gap between minorities and non-minorities in Texas, a staggering 90 percent, was driven by the elimination of affirmative action in the 1990s. JEL Classification: I21, I23, J15, J2

    What can go wrong will go wrong: Birthday effects and early tracking in the German school system

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    At the age of ten German pupils are given a secondary school track recommendation which largely determines the actual track choice. Track choice has major effects on the life course, mainly through labor market outcomes. Using data from the German PISA extension study, we analyze the effect of month of birth and thus relative age on such recommendations. We find that younger pupils are less often recommended to and actually attend Gymnasium, the most attractive track in terms of later life outcomes. Flexible enrolment and grade retention partly offset these inequalities and the relative age effect dissipates as students age
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