Project design with limited commitment and teams

We study the interaction between a group of agents who exert effort to complete a project and a manager who chooses its objectives. The manager has limited commitment power so that she can commit to the objectives only when the project is sufficiently close to completion. We show that the manager has incentives to extend the project as it progresses. This result has two implications. First, the manager will choose a larger project if she has less commitment power. Second, the manager should delegate the decision rights over the project size to the agents unless she has sufficient commitment power

Correlation of pre-existing radial artery macrocalcifications with late patency of primary radiocephalic fistulas in diabetic hemodialysis patients

ObjectiveThe aim of this study was to evaluate the impact of pre-existing radial artery macrocalcification (Mönckeberg type of arteriosclerosis) on patency rates of radiocephalic fistulas (RCFs) in diabetic end-stage renal disease (ESRD) patients undergoing hemodialysis.MethodsIn this observational prospective study, the long-term patency rates (primary outcome measures) of RCFs in ESRD diabetics who had Mönckeberg radial (±brachial) artery disease (calcified [C] group) were compared with those obtained in ESRD diabetics who had healthy, noncalcified vessels before RCF construction (healthy [H] group). Vessel calcification was assessed by plain two-dimensional radiography. For inclusion in the C-group, uniform linear railroad track-type macrocalcifications of at least 6 cm in length, in the medial wall of the radial artery ipsilateral to RCF creation, were required. Patients were included in the H-group if the radial artery ipsilateral to the RCF creation was free of any macrocalcification, of either intima or media type. Any intimal-like plaque with irregular and patchy distribution was an exclusion criterion for both groups. Patients in both groups also were required to have suitable upper limb vascular anatomy on the basis of ultrasound imaging before RCF creation (cephalic vein of minimum diameter of 1.6 mm, without stenosis or thrombosis in all outflow areas, and radial artery of minimum diameter of 1.5 mm, without proximal hemodynamically significant stenosis). Secondary outcome measures included all-cause mortality. Kaplan-Meier statistics were used for comparison between groups.ResultsThe arm radiograph at the site of possible fistula construction showed abnormality in 39 patients (C-group, 47 RCFs), whereas 33 patients had noncalcified (“healthy”) vascular anatomy (H-group, 40 RCFs). Mean duration of the diabetic disease at the time of RCF creation was 8.9 ± 5.6 years (range, 2-25 years) for the H-group and 14 ± 9.9 years (range, 1-40 years) for the C-group (P = .018). The mean follow-up period for H-group and C-group was 51.9 ± 35.9 months (range, 0.1-126 months) and 26.1 ± 31.6 months (range, 0.1-144 months), respectively (P = .0006). Forty-four patients died during the follow-up period. Primary patency rates at 12, 24, 36, and 48 months for C-group vs H-group were 50.2% vs 80%, 36.5% vs 72.3%, 32.4% vs 67.9%, and 29.1% vs 59.3% (P = .0019). Respective values for secondary patency rates were 52.4% vs 87.5%, 40.9% vs 82.4%, 36.6% vs 78.1%, and 33.2% vs 72.8% (P = .00064). Patient survival rates at 24 and 48 months were 56.1% and 46.4% for C-group and 92.4% and 67.4% for H-group, respectively (P = .05).ConclusionsESRD diabetics with radial artery Mönckeberg calcifications receiving RCFs had worse late clinical outcomes compared with ESRD diabetics with healthy distal arm vessels receiving the same access. The long-term benefit of RCFs may be lost in diabetics with extensively calcified vessels, and preferably the brachial artery should be used instead

Profit-oriented resource allocation using online scheduling in flexible heterogeneous networks

In this paper, we discuss a generalized measurement-based adaptive scheduling framework for dynamic resource allocation in flexible heterogeneous networks, in order to ensure efficient service level performance under inherently variable traffic conditions. We formulate our generalized optimization model based on the notion of a “profit center” with an arbitrary number of service classes, nonlinear revenue and cost functions and general performance constraints. Subsequently, and under the assumption of a linear pricing model and average queue delay requirements, we develop a fast, low complexity algorithm for online dynamic resource allocation, and examine its properties. Finally, the proposed scheme is validated through an extensive simulation study.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47990/1/11235_2006_Article_6525.pd

Early life child micronutrient status, maternal reasoning, and a nurturing household environment have persistent influences on child cognitive development at age 5 years: Results from MAL-ED

Background: Child cognitive development is influenced by early-life insults and protective factors. To what extent these factors have a long-term legacy on child development and hence fulfillment of cognitive potential is unknown. Objective: The aim of this study was to examine the relation between early-life factors (birth to 2 y) and cognitive development at 5 y. Methods: Observational follow-up visits were made of children at 5 y, previously enrolled in the community-based MAL-ED longitudinal cohort. The burden of enteropathogens, prevalence of illness, complementary diet intake, micronutrient status, and household and maternal factors from birth to 2 y were extensively measured and their relation with the Wechsler Preschool Primary Scales of Intelligence at 5 y was examined through use of linear regression. Results: Cognitive T-scores from 813 of 1198 (68%) children were examined and 5 variables had significant associations in multivariable models: mean child plasma transferrin receptor concentration (β: −1.81, 95% CI: −2.75, −0.86), number of years of maternal education (β: 0.27, 95% CI: 0.08, 0.45), maternal cognitive reasoning score (β: 0.09, 95% CI: 0.03, 0.15), household assets score (β: 0.64, 95% CI: 0.24, 1.04), and HOME child cleanliness factor (β: 0.60, 95% CI: 0.05, 1.15). In multivariable models, the mean rate of enteropathogen detections, burden of illness, and complementary food intakes between birth and 2 y were not significantly related to 5-y cognition. Conclusions: A nurturing home context in terms of a healthy/clean environment and household wealth, provision of adequate micronutrients, maternal education, and cognitive reasoning have a strong and persistent influence on child cognitive development. Efforts addressing aspects of poverty around micronutrient status, nurturing caregiving, and enabling home environments are likely to have lasting positive impacts on child cognitive development.publishedVersio

Optimal reservation policies and market segmentation

When operating in a market with heterogeneous customers, a service firm (e.g., a car rental company or a hotel) needs to manage its capacity so as to maximize its revenue. To gauge the potential demand, a service firm often allows each customer to reserve a unit of service in advance. However, to avoid the loss associated with “no-shows”, service firms may require a non-refundable deposit. To determine an optimal reservation policy with a non-refundable deposit, we consider the case in which the market is divided into four segments (high vs. low valuation and high vs. low show-up probability). When customer demand and the firm׳s capacity are large so that they can be approximated by continuous values, we determine the optimal reservation policy analytically, and we establish analytical conditions under which the firm should discriminate against (i.e., price out) certain customer segments. For the case when customer demand and the firm׳s capacity are finite so that they take on discrete values, we find that some of the insights obtained from the “continuous” case continue to hold especially when the firm׳s capacity is large. However, the key difference is that in the former case, the firm discriminates mostly based on customers׳ valuation, whereas in the latter case it discriminates mostly based on customers׳ show-up probability

Transactional e-Government Services: an Integrated Approach

Although form-based services are fundamental to e-government activities, their widespread does neither meet the citizen's expectations, nor the offered technological potential. The main reason for this lag is that traditional software engineering approaches cannot satisfactorily handle all of electronic services lifecycle aspects. In this paper we present experiences from the Greek Ministry of Finance's e-services lifecycle, and propose a new approach for handling e-service projects. The proposed approach has been used successfully for extending existing services, as well as developing new ones