Evaluating the Trade-off Between Energy Efficiency and QoE in Wireless Mesh Networks

The increasing usage of wireless networks creates new challenges for wireless access providers. On the one hand, providers want to satisfy the user demands but on the other hand, they try to reduce the operational costs by decreasing the energy consumption. In this paper, we evaluate the trade-off between energy efficiency and quality of experience for a wireless mesh testbed. The results show that by intelligent service control, resources can be better utilized and energy can be saved by reducing the number of active network components. However, care has to be taken because the channel bandwidth varies in wireless networks. In the second part of the paper, we analyze the trade-off between energy efficiency and quality of experience at the end user. The results reveal that a provider's service control measures do not only reduce the operational costs of the network but also bring a second benefit: they help maximize the battery lifetime of the end-user device.

Studying Effects of Primary Care Physicians and Patients on the Trade-Off Between Charges for Primary Care and Specialty Care Using a Hierarchical Multivariate Two-Part Model

Objective. To examine effects of primary care physicians (PCPs) and patients on the association between charges for primary care and specialty care in a point-of-service (POS) health plan. Data Source. Claims from 1996 for 3,308 adult male POS plan members, each of whom was assigned to one of the 50 family practitioner-PCPs with the largest POS plan member-loads. Study Design. A hierarchical multivariate two-part model was fitted using a Gibbs sampler to estimate PCPs' effects on patients' annual charges for two types of services, primary care and specialty care, the associations among PCPs' effects, and within-patient associations between charges for the two services. Adjusted Clinical Groups (ACGs) were used to adjust for case-mix. Principal Findings. PCPs with higher case-mix adjusted rates of specialist use were less likely to see their patients at least once during the year (estimated correlation: –.40; 95% CI: –.71, –.008) and provided fewer services to patients that they saw (estimated correlation: –.53; 95% CI: –.77, –.21). Ten of 11 PCPs whose case-mix adjusted effects on primary care charges were significantly less than or greater than zero (p < .05) had estimated, case-mix adjusted effects on specialty care charges that were of opposite sign (but not significantly different than zero). After adjustment for ACG and PCP effects, the within-patient, estimated odds ratio for any use of primary care given any use of specialty care was .57 (95% CI: .45, .73). Conclusions. PCPs and patients contributed independently to a trade-off between utilization of primary care and specialty care. The trade-off appeared to partially offset significant differences in the amount of care provided by PCPs. These findings were possible because we employed a hierarchical multivariate model rather than separate univariate models.

Carotenoid-based plumage colors and immune function: Is there a trade-off for rare carotenoids?

Theory suggests that carotenoid-based signals are used in animal communication because they contain specific information about parasite resistance or immunocompetence. This implies that honesty of carotenoid-based signals is maintained by a trade-off between pigmentation and immune function for carotenoids, assuming that the carotenoids used for coloration are also immunoenhancing. We tested this hypothesis by altering the diets of nestling great tits (Paris major) with supplementary beadlets containing the carotenoids that are naturally ingested with food or beadlets containing the carotenoids that are incorporated into the feathers; a control group received beadlets containing no carotenoids. We simultaneously immune challenged half of the nestlings of each supplementation group, using a two-factorial design. Activatior of the immune system led to reduced color expression. However, only nestlings fed with the naturally ingested carotenoids and not with the carotenoids deposited in the feathers showed an increased cellular immune response. This shows that the carotenoids used for ornamentation do not promote the immune function, which conflicts with the trade-off hypothesis. Our results indicate that honesty of carotenoid-based signals is maintained by an individual's physiological limitation to absorb and/or transport carotenoids and by access to carotenoids, indicating that preferences for carotenoid-based traits in sexual selection or parent-offspring interactions select for competitive individuals, rather than specifically for immune function.

Trade-off study on deorbiting S/C in near polar orbit

Usual long, flexible, ED tethers kept vertical by the gravity gradient might be less efficient for deorbiting S/C in near-polar orbits than conventional (Hall, Ion) electrical thrusters. A trade-off study on this application is here presented for tethers kept horizontal and perpendicular to the orbital plane. A tether thus oriented must be rigid and short for structural reasons, requiring a non-convex cross section and a power supply as in the case of electrical thrusters. Very recent developments on bare-tether collection theory allow predicting the current collected by an arbitrary cross section. For the horizontal tether, structural considerations on length play the role of ohmic effects in vertical tethers, in determining the optimal contribution of tether mass to the overall deorbiting system. For a given deorbiting-mission impulse, tether-system mass is minimal at some optimal length that increases weakly with the impulse. The horizontal-tether system may beat both the vertical tether and the electrical thruster as regards mass requirements for a narrow length range centered at about 100 m, allowing, however, for a broad mission-impulse range.

Flexibility versus Stability: A difficult trade-off in the eurozone. CEPS Working Document No. 422, 29 April 2016

Optimal currency area (OCA) theory has been influential in pushing eurozone countries towards structural reforms to make product and labour markets more flexible. The underlying assumption of the OCA prescription for structural reform is that asymmetric shocks are permanent. However, when shocks are temporary it does not follow that more flexibility is the answer. When shocks are the result of business-cycle movements, the way to deal with them is by stabilisation efforts. This paper provides empirical evidence that suggests that the biggest shocks in the eurozone were the result of business-cycle movements. These were relatively well synchronised, except for their amplitude. We argue that efforts to stabilise business cycles should be strengthened relative to the efforts that have been made to impose structural reforms, with consideration given to the implications for the governance of the eurozone.

A Bayesian formulation of search, control and the exploration/exploitation trade-off

A new approach to optimisation is introduced based on a precise probabilistic statement of what is ideally required of an optimisation method. It is convenient to express the formalism in terms of the control of a stationary environment. This leads to an objective function for the controller which unifies the objectives of exploration and exploitation, thereby providing a quantitative principle for managing this trade-off. This is demonstrated using a variant of the multi-armed bandit problem. This approach opens new possibilities for optimisation algorithms, particularly by using neural network or other adaptive methods for the adaptive controller. It also opens possibilities for deepening understanding of existing methods. The realisation of these possibilities requires research into practical approximations of the exact formalism.

Is there a trade-off between quality and productivity? The case of diagnostic technologies in Portugal

The purpose of this paper is twofold: first, we compute quality-adjusted measures of productivity change for the three most important diagnostic technologies (i.e., the Computerised Tomography Scan, Electrocardiogram and Echocardiogram) in the major Portuguese hospitals. We use the Malmquist–Luenberger index, which allows to measure productivity growth while controlling for the quality of the production. Second, using non-parametric tests, we analyse whether the implementation of the Prospective Payment System may have had a positive impact on the movements of productivity over time. The results show that the PPS has helped hospitals to use these tools more efficiently and to improve their effectiveness.

Location Privacy Preferences : A Survey-Based Analysis of Consumer Awareness, Trade-off and Decision-Making

Peer reviewed

Location Privacy Preferences : A Survey-Based Analysis of Consumer Awareness, Trade-off and Decision-Making

Peer reviewed

Controller Time and Delay Costs - a Trade-off Analysis

Air traffic controller shortages remain a significant challenge in European ATM. Comparing different rules, we quantify the cost effectiveness of adding controller hours to Area Control Centre regulations to avert the delay cost impact on airlines. Typically, adding controller hours results in a net benefit. Distributions of delay duration and aircraft weight play an important role in determining the total cost of a regulation. Errors are likely to be incurred when analysing performance based on average delay values, particularly at the disaggregate level.

Expanding Agri-Food Production and Employment in the Presence of Climate Policy Constraints: Quantifying the Trade-Off in Ireland

This chapter explores the trade-off between competing objectives of employment creation and climate policy commitments in Irish agriculture. A social accounting matrix (SAM) multiplier model is linked with a partial equilibrium agricultural sector model to simulate the impact of a number of GHG emission reduction scenarios, assuming these are achieved through a constraint on beef production. Limiting the size of the beef sector helps to reduce GHG emissions with a very limited impact on the value of agricultural income at the farm level. However, the SAM multiplier analysis shows that there would be significant employment losses in the wider economy. From a policy perspective, a pragmatic approach to GHG emissions reductions in the agriculture sector, which balances opportunities for economic growth in the sector with opportunities to reduce associated GHG emissions, may be required.