3,402 research outputs found
Breast Cancer Treatment Practices in Elderly Women in a Community Hospital
Background. Elderly women with breast cancer are considered underdiagnosed and undertreated, and this adversely affects their overall survival. Methods. A total of 393 female breast cancer patients aged 70 years and older, diagnosed within the years 1989–1999, were identified from the tumor registry of The Brooklyn Hospital Center. Comparisons between the 3 different subgroups 70–74, 75–79, and 80 years and older were made using the Pearson Chi Square test. Results. Lumpectomy was performed in 42% of all patients, while mastectomy was done in 46% of patients. Adjuvant therapy such as chemotherapy, radiation therapy, and hormonal therapy were done in 12%, 25%, and 38%, respectively. Forty-seven percent of patients with positive lymph nodes received chemotherapy. Eighty-six percent of patients who were estrogen receptor-positive received adjuvant hormonal therapy. Overall five-year survival was only 14% for the ≥80 age group, compared to that of 32% and 35% for the 70–74 and the 75–79 age groups, respectively. Conclusions. Surgery was performed in majority of these patients, about half received lumpectomy, the other half mastectomy. Adjuvant therapies were frequently excluded, with only hormonal therapy being the most commonly used. Overall five-year survival is significantly worse in patients ≥80 years with breast cancer
Assortment optimisation under a general discrete choice model: A tight analysis of revenue-ordered assortments
The assortment problem in revenue management is the problem of deciding which
subset of products to offer to consumers in order to maximise revenue. A simple
and natural strategy is to select the best assortment out of all those that are
constructed by fixing a threshold revenue and then choosing all products
with revenue at least . This is known as the revenue-ordered assortments
strategy. In this paper we study the approximation guarantees provided by
revenue-ordered assortments when customers are rational in the following sense:
the probability of selecting a specific product from the set being offered
cannot increase if the set is enlarged. This rationality assumption, known as
regularity, is satisfied by almost all discrete choice models considered in the
revenue management and choice theory literature, and in particular by random
utility models. The bounds we obtain are tight and improve on recent results in
that direction, such as for the Mixed Multinomial Logit model by
Rusmevichientong et al. (2014). An appealing feature of our analysis is its
simplicity, as it relies only on the regularity condition.
We also draw a connection between assortment optimisation and two pricing
problems called unit demand envy-free pricing and Stackelberg minimum spanning
tree: These problems can be restated as assortment problems under discrete
choice models satisfying the regularity condition, and moreover revenue-ordered
assortments correspond then to the well-studied uniform pricing heuristic. When
specialised to that setting, the general bounds we establish for
revenue-ordered assortments match and unify the best known results on uniform
pricing.Comment: Minor changes following referees' comment
Reaction Time of a Group of Physics Students
The reaction time of a group of students majoring in Physics is reported
here. Strong co-relation between fatigue, reaction time and performance have
been seen and may be useful for academicians and administrators responsible of
working out time-tables, course structures, students counsellings etc.Comment: 10 pages, 4 figure
On quantum coding for ensembles of mixed states
We consider the problem of optimal asymptotically faithful compression for
ensembles of mixed quantum states. Although the optimal rate is unknown, we
prove upper and lower bounds and describe a series of illustrative examples of
compression of mixed states. We also discuss a classical analogue of the
problem.Comment: 23 pages, LaTe
Q-Strategy: A Bidding Strategy for Market-Based Allocation of Grid Services
The application of autonomous agents by the provisioning and usage of computational services is an attractive research field. Various methods and technologies in the area of artificial intelligence, statistics and economics are playing together to achieve i) autonomic service provisioning and usage of Grid services, to invent ii) competitive bidding strategies for widely used market mechanisms and to iii) incentivize consumers and providers to use such market-based systems.
The contributions of the paper are threefold. First, we present a bidding agent framework for implementing artificial bidding agents, supporting consumers and providers in technical and economic preference elicitation as well as automated bid generation by the requesting and provisioning of Grid services. Secondly, we introduce a novel consumer-side bidding strategy, which enables a goal-oriented and strategic behavior by the generation and submission of consumer service requests and selection of provider offers. Thirdly, we evaluate and compare the Q-strategy, implemented within the presented framework, against the Truth-Telling bidding strategy in three mechanisms – a centralized CDA, a decentralized on-line machine scheduling and a FIFO-scheduling mechanisms
Rational bidding using reinforcement learning: an application in automated resource allocation
The application of autonomous agents by the provisioning and usage of computational resources is an attractive research field. Various methods and technologies in the area of artificial intelligence, statistics and economics are playing together to achieve i) autonomic resource provisioning and usage of computational resources, to invent ii) competitive bidding strategies for widely used market mechanisms and to iii) incentivize consumers and providers to use such market-based systems.
The contributions of the paper are threefold. First, we present a framework for supporting consumers and providers in technical and economic preference elicitation and the generation of bids. Secondly, we introduce a consumer-side reinforcement learning bidding strategy which enables rational behavior by the generation and selection of bids. Thirdly, we evaluate and compare this bidding strategy against a truth-telling bidding strategy for two kinds of market mechanisms – one centralized and one decentralized
Nonstationary Stochastic Resonance in a Single Neuron-Like System
Stochastic resonance holds much promise for the detection of weak signals in
the presence of relatively loud noise. Following the discovery of nondynamical
and of aperiodic stochastic resonance, it was recently shown that the
phenomenon can manifest itself even in the presence of nonstationary signals.
This was found in a composite system of differentiated trigger mechanisms
mounted in parallel, which suggests that it could be realized in some
elementary neural networks or nonlinear electronic circuits. Here, we find that
even an individual trigger system may be able to detect weak nonstationary
signals using stochastic resonance. The very simple modification to the trigger
mechanism that makes this possible is reminiscent of some aspects of actual
neuron physics. Stochastic resonance may thus become relevant to more types of
biological or electronic systems injected with an ever broader class of
realistic signals.Comment: Plain Latex, 7 figure
Singularites in the Bousseneq equation and in the generalized KdV equation
In this paper, two kinds of the exact singular solutions are obtained by the
improved homogeneous balance (HB) method and a nonlinear transformation. The
two exact solutions show that special singular wave patterns exists in the
classical model of some nonlinear wave problems
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