88 research outputs found
Optimal harvesting under marine reserves and uncertain environment
No full textPersistence in the literature is the perception of an inherent tradeoff between ecological conservation and economic harvesting goals. Overexploitation may lead to resource destruction, including extinction. Conservation measures should be decided and implemented. A standard ecological response is to impose no-take areas or marine reserves. In this paper, our objective is to study a harvesting management problem under the constraints of a no-take area, which we formulate mathematically as a bi-dimensional singular stochastic control problem. Using dynamic programming theory, we characterise our value function as the unique solution to a HJB equation. We also describe the optimal harvesting strategy by identifying the harvesting and non-harvesting regions. We show that setting up reserve area not only leads to a better ecological conservation but may also increase the economic benefit for fishing industry in the long run. We further enrich our studies with some numerical analysis, enabling us to get some insightful understanding on the size of the reserve area where no-take policy should be implemented
Combination chemotherapy for metastatic or recurrent carcinoma of the breast--a randomized phase III trial comparing CAF versus VATH versus VATH alternating with CMFVP: Cancer and Leukemia Group B Study 8281.
No full textPURPOSE We sought to compare three doxorubicin-based therapies for metastatic breast cancer for response frequency, time to treatment failure (TTF), and survival. MATERIALS AND METHODS Women with metastatic breast cancer who had measurable disease, required laboratory tests, had received no prior chemotherapy for metastases, had a Cancer and Leukemia Group B (CALGB) performance status < or = 2, and provided informed consent were eligible. Treatment included the following: arm I--cyclophosphamide, doxorubicin, and fluorouracil (CAF); arm II--vinblastine, doxorubicin, thiotepa, and halotestin (VATH); and arm III--VATH alternating with cyclophosphamide, methotrexate, fluorouracil, vincristine, and prednisone (CMFVP) on cycles 3, 5, 7, 9, etc. Doses were modified for toxicities. Standard CALGB response and toxicity criteria were used. RESULTS Between August 1982 and February 1987, 497 women were entered and 491 were treated on study. Pretreatment characteristics were well balanced and the median follow-up duration was 79 months. There were no significant differences in response (complete [CR] plus partial [PR]) at 50% on arm I, 57% on arm II, and 51% on arm III. The median TTFs were 8, 8, and 9 months, respectively, in favor of arm III when compared with arm I (P = .028). The median survival times for treatment arms I, II, and III were 15, 17, and 17 months, respectively. After multivariate regression analyses, only estrogen receptors (ER), performance status, and number of metastatic sites influenced TTF and survival. Leukopenia was the most common grade 3 or 4 toxicity, occurring in 90%, 80%, and 92% of patients per arm, respectively. Lethal toxicities were seen in four, five, and six women, respectively. Overall, there were more grade > or = 3 toxicities on arm II than I, and most occurred on arm III (P = .02). CONCLUSION The VATH regimen appears similarly effective to the CAF regimen as initial therapy. Alternating CMFVP with VATH did not improve response rate or survival. After accounting for other variables, treatment arm was not related to outcome. New therapeutic regimens are still needed. </jats:sec
Bid-Ask Spread Modelling, a Perturbation Approach
No full textOur objective is to study liquidity risk, in particular the so-called “bid-ask spread”, as a by-product of market uncertainties. “Bid-ask spread”, and more generally “limit order books” describe the existence of different sell and buy prices, which we explain by using different risk aversions of market participants. The risky asset follows a diffusion process governed by a Brow- nian motion which is uncertain. We use the error theory with Dirichlet forms to formalize the notion of uncertainty on the Brownian motion. This uncer- tainty generates noises on the trajectories of the underlying asset and we use these noises to expound the presence of bid-ask spreads. In addition, we prove that these noises also have direct impacts on the mid-price of the risky asset. We further enrich our studies with the resolution of an optimal liquidation problem under these liquidity uncertainties and market impacts. To complete our analysis, some numerical results will be provided
Agreement of Parents and Children on Characteristics of Pediatric Headache, Other Pains, Somatic Symptoms, and Depressive Symptoms in an Epidemiologic Study
No full textBackground: The objective of the present Study was to assess the concordance between parent and child report regarding different domains of pediatric health, headache in particular. In addition, the influence of potential moderator variables on the agreement between parents and children was examined. Methodology: In an epidemiologic study on a randomly drawn sample of households with at least I child in the family between 7 and 14 years of age (community registries), various pediatric health disturbances (headache other pains, somatic symptoms, and depression/anxiety) were assessed via both child (from the age of 9 y on) and parent report (n = 3461). Results: A relatively high parent-child agreement (sigma(M) = 0.61) was found regarding the variable headache frequency, whereas consensus regarding other pains was, for the most part, markedly lower. The lowest agreement (sigma(M) = 0.27) was found for depression/anxiety symptoms. A moderator analysis (with age, sex, and parental headache) between child and parent failed to reveal significant differences regarding the degree of agreement between the 2 data sources. Children reported more frequent and more severe symptoms in all health domains. Conclusion: The examined potential moderator variables did not elucidate processes underlying the differences in child and parent agreement. There is no convincing evidence that the children's appraisal is less valid than their parents'. In summary, parents' reports cannot be viewed as a substitute for children's reports in pediatric pain and health assessment. Instead, each perspective represents a unique Subjective reality and as such, both are of importance for research on pediatric pain and other health variables
A Mixed Singular/Switching Control Problem for a Dividend Policy with Reversible Technology Investment.
No full textPostsurgical adjuvant chemotherapy of stage II breast carcinoma with or without crossover to a non-cross-resistant regimen: a Cancer and Leukemia Group B study.
No full textPURPOSE To compare two cyclophosphamide, methotrexate, fluorouracil, vincristine, and prednisone (CMFVP) regimens with a doxorubicin-based regimen--vinblastine, doxorubicin, thiotepa, and Halotestin (Upjohn, Kalamazoo, MI) (VATH)--in patients with stage II node-positive breast carcinoma. METHODS Nine hundred forty-five women were treated with a 6-week induction course of CMFVP. They were then randomized to receive one of two consolidation CMFVP regimens: 6-week courses or 2-week courses. Following completion of CMFVP consolidation, patients were again randomized to either continue the CMFVP regimen or to receive six escalating doses of VATH. RESULTS Among all patients, with a median follow-up time of 11.5 years, there is no statistically significant difference in disease-free survival (DFS) between the two consolidation CMFVP regimens. VATH intensification treatment is statistically significantly superior to CMFVP in terms of DFS (P = .0040). For patients with one to three involved nodes, there is currently no significant difference between VATH and CMFVP; however, among those with four or more positive lymph nodes, there is a significant difference in favor of VATH (P = .0037). There is also improved overall survival with VATH (P = .043; median, > 14 years v 10 years). This difference is also statistically significant in patients with four or more involved lymph nodes, among postmenopausal patients, and among postmenopausal estrogen receptor-positive patients. CONCLUSION Chemotherapy with crossover to escalating doses of VATH following CMFVP was well tolerated and effective. Inauguration of VATH as a treatment intensification at the eighth month produced a major increase in relapse-free and overall survival. The observation that sensitivity to VATH is retained so long after mastectomy raises questions about the proper duration of adjuvant chemotherapy and lends support to further investigation of cross-over designs in future trials to postoperative adjuvant chemotherapy regimens. </jats:sec
Vath, Wm. Caleb (Death, 1906-08-24)
No full textAddress: 3409 StathemAge at death: 39 yrs.394/Pg 107/1906/M W M/Ind./Dr. L. D. Clayton/Fred Walber/Spring GroveOriginal record filed in drawer labeled 'VARNEY-VOESTER'
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Educating Hong Kong's youth.
No full textThis report describes the research and analysis conducted for the improvement of Caritas Charles Vath College, an alternative high school in Hong Kong. This project investigated issues ranging from students' low motivation and self-esteem to discipline in the classroom. The final recommendations were designed to help maintain order in the classroom, keep students motivated and interested, and provide support for both students and teachers, in order to help the school in its mission to produce more successful citizens
Modular Frame Concept Cart for Inspection of Slab-On-Girder Bridge Superstructure
No full textAccessibility of bridge superstructures is often a major issue for the cost-effective inspection and for the installation of health monitoring systems. Depending on the case studies under consideration, tailored solutions may be required to best suit particular needs. This paper presents a concept cart that has been conceived, designed and built to allow a minimum of two operators to move along the whole length of the steel I-girders of a 263 m five span continuous slab-on-girder bridge. the vehicle has been equipped with a set of built-in devices, used to rapidly pass through the transverse stiffeners and cross frames, also at the bent locations. This solution allowed the successful installation of a 1.1 km fiber optic circuit for strain and temperature monitoring
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