Protecting local access telecommunications networks: Toward a minimum-cost solution

The problem of designing fibre-optic networks for local-access telecommunications generates (at least) three non-trivial subproblems. In the first of these subproblems one must determine how many fibre-optic cables (fibres) are required at either end of a street. In the next subproblem a minimum-cost network must be designed to support the fibres. The network must also provide distinct paths from either end of the street to the central exchange(s). Finally, the fibre-optic cables must be placed in protective covers. These covers are available in a number of different sizes, allowing some flexibility when covering each section of the network. In this paper we describe a dynamic programming (DP) formulation for finding a minimum-cost (protective) covering for the network (the third of the subproblems). This problem is a generalised set covering problem with side constraints and is further complicated by the introduction of fixed and variable welding costs. The DP formulation selects covers along each arc (in the network), but cannot exactly model the fixed costs and so does not guarantee optimality. We also describe an integer programming (IP) formulation for assessing the quality of the DP solutions. The cost of the networks constructed by the IP model is less than those designed using the DP model, but the saving is not significant for the problems examined (less than 0.1%). This indicates that the DP model will generally give very good solutions. Furthermore, as the problem dimensions grow, DP gives significantly better solution times than IP.     

Life is pleasant--and memory helps to keep it that way!

People's recollections of the past are often positively biased. This bias has 2 causes. The 1st cause lies in people's perceptions of events. The authors review the results of several studies and present several new comparative analyses of these studies, all of which indicate that people perceive events in their lives to more often be pleasant than unpleasant. A 2nd cause is the fading affect bias: The affect associated with unpleasant events fades faster than the affect associated with pleasant events. The authors review the results of several studies documenting this bias and present evidence indicating that dysphoria (mild depression) disrupts such bias. Taken together, this evidence suggests that autobiographical memory represents an important exception to the theoretical claim that bad is stronger than good. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Large deflection dynamics and control for planar continuum robots

This paper focuses on a class of robot manipulators termed "continuum" robots - robots that exhibit behavior similar to tentacles, trunks, and snakes. In previous work, we studied details of the mechanical design, kinematics, path-planning and small-deflection dynamics for continuum robots such as the Clemson "tentacle manipulator". In this paper, we discuss the dynamics of a planar continuum backbone section, incorporating a large-deflection dynamic model. Based on these dynamics, we formulate a vibration-damping setpoint controller, and include experimental results to illustrate the efficacy of the proposed controller.     

Thoracic epidural anesthesia as the last option for treating angina in a patient before coronary artery bypass surgery

Robertsonian translocations, although relatively common as a constitutional genetic aberration, are rarely encountered in leukaemia. We report a case of acute myeloid leukaemia which showed an acquired Robertsonian translocation in the form of der(14;21) by cytogenetic analysis of leukaemic cells. This was confirmed by the PHA-stimulated culture of peripheral blood lymphocytes. A review of the literature identifies only eight reported cases of acquired Robertsonian translocations in leukaemia. In the majority of cases the Robertsonian translocation occurs as a secondary change in a complex abnormal clone, whereas in two out of nine patients reported, including ours, it is found as a sole karyotypic abnormality.     

Secobarbital in humans discriminating triazolam under two-response and novel-response procedures

The percentage of long-term survivors after intensive chemotherapy and the outcome of MDS patients who achieve partial remission (PR) with intensive chemotherapy (IC) are not known. Between 1981 and 1996 we treated 99 patients with de novo MDS who had high-risk MDS or progression to AML, with IC. 41 (41%) achieved CR, 16 (16%) achieved partial remission (PR), 26 (26%) had failure, and 16 (16%) died in aplasia. Eight of the patients who achieved CR were autografted, three were allografted and the remaining cases received moderate consolidation chemotherapy. After IC, the 16 PR patients fulfilled the criteria for RA in 15 cases and CMML in one case. Median PR duration was 17 months, and three PR were > 3 years (39, 50+, 82+ months). Median actuarial survival of patients who achieved PR and CR was 18 months and 20 months from the onset of IC, respectively (difference not significant). Of the 71 patients treated before 1993, with sufficient follow-up, 10 (14%) had survived > 4 years (long-term survivors). Four of them were alive in first CR after 49+ to 110+ months and probably cured, two were alive in PR after 50+ and 82+ months and four had died after 49-78 months. Long-term survivors were characterized by a significantly higher incidence of RAEB-T at diagnosis, and with normal or favourable cytogenetic findings. In patients with RAEB-T at diagnosis included before 1993, 8/23 (35%) cases who had no unfavourable karyotype had survived > 4 years. Our findings suggest that MDS patients who achieve PR with IC, and not only those who achieve CR, can benefit from this type of treatment. The percentage of long-term survivors remains low, however, and is almost restricted to patients with RAEB-T at diagnosis and no unfavourable karyotype.     

Squamous cell carcinoma of the prostate: case report and review of literature

Carcinoma of the prostate, that is adenocarcinoma, is one of the most common malignancies in the male with an estimated incidence for 1991 of 122,000 new cases. On the other hand, squamous cell carcinoma of the prostate, with a median incidence of .5%-1% of all prostatic malignancies, has a similar clinical presentation but differs in treatment response and prognosis. We herein present one case of this histological pattern and review the literature pertaining to it.     

Health research in the developing world: a gastroenterological view from Bangladesh

OBJECTIVES: To identify knowledge levels of academic surgeons about Food and Drug Administration (FDA) and Institutional Review Board (IRB) regulations for clinical research and to determine whether being a member in an IRB, conducting or participating in clinical trials, or being a member in surgical societies affected knowledge levels. DESIGN: Survey of surgical department faculty members in 20 universities. RESULTS: Sixty-five responses were received from 14 sites. Overall mean (+/- SEM) correct score was 6.7 +/- 0.2 of a possible 20 points. The best predictor of overall score was being a primary investigator of a clinical trial (P < .001), followed by being or having been a member of an IRB (P < or = .02). The total mean score of members of the Surgical Infection Society (8.2 +/- 0.5) was significantly higher (P < .001) than that of nonmembers (6.1 +/- 0.2), a phenomenon not observed with other surgical societies. In certain hypothetical clinical scenarios, all respondents were mistakenly willing to conduct clinical trials without obtaining appropriate approval from the FDA. Four (22%) of 18 IRB member respondents and 16 (25%) of the 65 respondents were willing to conduct human research without appropriate approval from patients, the IRB, or both. CONCLUSIONS: Knowledge deficits exist in the academic surgical community about the role and requirements of the FDA and local IRBs for conducting clinical research. Further study is required to determine the reasons for this deficit and to identify appropriate interventions.     

Childhood fibrous dysplasia presenting as blindness: a skull base approach for resection and immediate reconstruction

Fibrous dysplasia is an abnormal fibroosseous process of bone of unknown cause. The incidence of skull involvement varies, painless enlargement being the most common presenting symptom. Change in vision is a rare but recognized finding. We report a 3-year-old boy with extreme fibrous dysplasia involving the skull base, who presented with blindness. He underwent exposure osteotomies of the frontal bones and orbits to provide access for skull base tumor removal. The orbital roofs were reconstructed with microplate-fixed cranial grafts. One and one half years after tumor excision followed by immediate reconstruction, the boy retains facial symmetry, and his ocular function has not deteriorated.