213 research outputs found

    Optimal Query Complexity for Reconstructing Hypergraphs

    Get PDF
    In this paper we consider the problem of reconstructing a hidden weighted hypergraph of constant rank using additive queries. We prove the following: Let GG be a weighted hidden hypergraph of constant rank with n vertices and mm hyperedges. For any mm there exists a non-adaptive algorithm that finds the edges of the graph and their weights using O(mlognlogm) O(\frac{m\log n}{\log m}) additive queries. This solves the open problem in [S. Choi, J. H. Kim. Optimal Query Complexity Bounds for Finding Graphs. {\em STOC}, 749--758,~2008]. When the weights of the hypergraph are integers that are less than O(poly(nd/m))O(poly(n^d/m)) where dd is the rank of the hypergraph (and therefore for unweighted hypergraphs) there exists a non-adaptive algorithm that finds the edges of the graph and their weights using O(mlogndmlogm). O(\frac{m\log \frac{n^d}{m}}{\log m}). additive queries. Using the information theoretic bound the above query complexities are tight

    EVALUATION FRAMEWORK FOR 3D COLLABORATIVE VIRTUAL ENVIRONMENTS (THE CORE)

    Get PDF
    As a consequence of the increasing interest in Collaborative Virtual Environments (CVEs) and the complex nature of such systems, the need for a thorough evaluation framework has become necessary. The current evaluation frameworks suffer from limitations in assessment because they are either confined to evaluation of a specific type of CVE or they focus on a restricted aspect of CVE. This paper presents a framework for THorough Evaluation of COllaborative viRtual Environment (THE CORE). The proposed framework is structured in a four-layered architecture to assure evaluation of the multi-faceted aspects comprising a CVE. The layers evaluate the application usability, tool usability, companion interaction and collaboration outcome. Within each layer, key evaluation tools and factors are provided. In addition, the framework is designed to be generic to be suitable for different types of CVEs. In order to validate the proposed framework, a case study was conducted involving development and evaluation of a 3D CVE. The case study found the four-layered framework to be useful for evaluating both the technical and behavioural aspects of the 3D CVE. As future work, the generality of the framework will be further tested on different types of CVE, potentially leading to modifications and extensions

    The physician and updates in cancer treatment: when to stop?

    Get PDF
    A questão do término da vida é fonte de reflexões desde os primórdios da civilização e demanda diligências para a tentativa de seu enquadramento social ao longo da história do pensamento humano. Com o desenvolvimento e aprimoramento da medicina, podese modificar, na maioria das vezes, a história natural das doenças. É possível prolongar a vida e adiar o processo do morrer. Isso engendrou um novo protótipo médico em que há necessidade de se conviver e cuidar de pacientes gravemente enfermos, situação muitas vezes acompanhada de árduo sofrimento. A sociedade atribui ao médico a função de ser o responsável por debelar e vencer a morte. No contexto oncológico, essas questões surgem de forma salutar, uma vez que, em diversas situações, não há possibilidade de se oferecer uma terapêutica curativa aos enfermos. O objetivo do presente artigo é debater as relações que norteiam a temática proposta, baseando-se em uma revisão de literatura. Busca-se, assim, uma perspectiva que figura como um caminho argumentativo que conduz evidências a esse debate.The issue of life-ending has been a source of considerations since the dawn of civilization, and calls for great circumspection when one attempts to fit it socially throughout the history of human thinking. The development and improvement of Medicine might modify, in most cases, the natural history of disease. We have managed to prolong life and the process of dying. This has created a new medical prototype that needs to care for terminally-ill patients, a situation often accompanied by severe suffering. Society attributes to the physician the role of being responsible for conquering and overcoming death. In the oncology context, these questions are well addressed, as in many situations there is no possibility to offer a curative treatment to the patients. The objective of the present study was to discuss the relations that guide the proposed theme, based on a medical literature review. Therefore, a perspective is sought as an argumentative alternative that brings evidence to the proposed debate

    The Impact of Communication on a Human-Agent Shared Mental Model and Team Performance (Extended Abstract)

    Get PDF
    ABSTRACT There is a growing interest in the use of heterogeneous teams comprised of humans and Intelligent Virtual Agents (IVAs). Human teamwork studies have provided cumulative knowledge about team features and performance; however, transfer of this knowledge to human-IVA teams is challenging. Novelly, this paper investigates the impact of multiple communication channels on the development and maintenance of a Shared Mental Model (SMM) between humans and IVAs. The results from two studies involving a collaborative activity show a significant positive relationship between the IVA's verbal and non-verbal communication and the development of a SMM related to taskwork and teamwork as perceived by the human teammate. Moreover, the results indicate that a SMM tends to improve overall team performance

    Cost-Effectiveness of Second-Line Chemotherapy/Biologics among Elderly Metastatic Colon Cancer Patients

    Get PDF
    INTRODUCTION: Advancements in chemotherapy treatment have improved the clinical management of metastatic colon cancer (mCC) patients. An increasing number of elderly mCC patients receive various combinations of regimens in second-line chemotherapy/biologics treatment (Tx2) after first-line treatment (Tx1) to prolong survival and/or palliate symptoms, but these regimens have higher costs. This analysis investigated the survival benefit and incremental cost associated with Tx2 among elderly mCC patients. METHODS: Elderly (aged ≥66 years) SEER-Medicare patients diagnosed with mCC in 2003–2007 were identified and followed until death or the end of 2009. Cox regression and partitioned least squares regression were utilized to obtain the survival benefit and incremental cost associated with Tx2 within a 5-year study period. A time-varying model was used to reduce bias due to sequential ordering of Tx1 and Tx2. The regressions controlled for patient demographic characteristics, clinical variables, and a proxy for poor performance. Bootstrapping was used to generate 95% confidence intervals (CI). RESULTS: Of the 3,266 elderly mCC patients who received Tx1, 2,744 (84%) died within the observation period; 1,440 (44%) received Tx2. The survival benefit associated with receipt of Tx2 was 0.33 years (95% CI 0.19–0.43), and the associated incremental cost was 40,888(9540,888 (95% CI 3,044–44,324). The incremental cost-effectiveness ratio (ICER) for Tx2 was 123,903 per life year gained (95% CI 9,600–216,082). CONCLUSION: The estimated survival benefit of receiving second-line chemotherapy/biologics was about 4 months, which is consistent with evidence from clinical trials. This improved survival was associated with an ICER that exceeds the traditional threshold. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s12325-014-0134-8) contains supplementary material, which is available to authorized users

    Composite signet-ring cell/neuroendocrine carcinoma of the stomach with a metastatic neuroendocrine carcinoma component: a better prognosis entity

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Mixed (composite) exocrine-neuroendocrine cell carcinomas are defined as an intimate admixture of neoplastic glandular exocrine and neuroendocrine cell types. Although gastric adenocarcinoma containing a small number of neuroendocrine cells is a relatively frequent occurrence, gastric neoplasms containing equal proportions of both cell types are rare.</p> <p>Case Presentation</p> <p>We present a case of composite exocrine (signet-ring cell)-neuroendocrine cell carcinoma, in which the neoplastic signet-ring cell exocrine and neuroendocrine constituents occurred in fairly equivalent amounts, whereas only the neuroendocrine carcinoma portion of the tumor represented the metastatic component. Light microscopy, immunohistochemical and electron microscopic findings are described, and the literature is reviewed.</p> <p>Conclusion</p> <p>This study confirms the ability of pluripotent precursor cells to differentiate into either adenocarcinoma or neuroendocrine tumor and, justifying the designation of composite exocrine-neuroendocrine cell carcinoma as the appropriate classification for this tumor. The protracted clinical course further supports the notion that composite signet-ring cell/neuroendocrine carcinoma tumors behave relatively less aggressively than the pure forms of the former cell type.</p

    Literature review of clinical results of total skin electron irradiation (TSEBT) of mycosis fungoides in adults

    Get PDF
    BackgroundMycosis fungoides (MF) is an extranodal, indolent non-Hodgkin lymphoma of T cell origin. Even with the establishment of MF staging, the initial treatment strategy often remains unclear.AimThe aim of this study was to review the clinical results of total skin electron beam therapy (TSEBT) for MF in adults published in English language scientific journals searched in Pubmed/Medline database until December 2012.ResultsMF is very sensitive to radiation therapy (RT) delivered either by photons or by electrons. In limited patches and/or plaques local electron beam irradiation results in good outcomes besides the fact of not being superior to other modalities. For extensive patches and/or plaques data suggest that TSEBT shows superior response rates. The cutaneous disease presentation is favorably managed with radiotherapy due to its ability to treat the full thickness of deeply infiltrated skin. For generalized erythroderma presentation, TSEBT seems to be an appropriate initial therapy. For advanced disease, palliation, or recurrence after the first radiotherapy treatment course, TSEBT may still be beneficial, with acceptable toxicity. Recommended dose is 30–36[[ce:hsp sp="0.25"/]]Gy delivered in 6–10 weeks.ConclusionTSEBT can be used to treat any stage of MF. It also presents good tumor response with symptoms of relief and a palliative effect on MF, either after previous irradiation or failure of other treatment strategies

    Deep inspiration breath hold: dosimetric benefits to decrease cardiac dose during postoperative radiation therapy for breast cancer patients

    Get PDF
    Background: Postoperative radiation therapy (RT) is the standard treatment for almost all patients diagnosed with breast cancer. Even with modern RT techniques, parts of the heart may still receive higher doses than those recommended by clinically validated dose limit restrictions, especially when the left breast is irradiated. Deep inspiration breath hold (DIBH) may reduce irradiated cardiac volume compared to free breathing (FB) treatment. This study aimed to evaluate the dosimetric impact on the heart and left anterior descending coronary artery (LAD) in FB and DIBH RT planning in patients with left breast cancer. Materials and methods: A retrospective cohort study of women diagnosed with left-sided breast cancer submitted to breast surgery followed by postoperative RT from 2015 to 2019. All patients were planned with FB and DIBH and  hypofractionated dose prescription (40.05 Gy in 15 fractions). Results: 68 patients were included in the study. For the coverage of the planned target volume evaluation [planning target volume (PTV) eval] there was no significant difference between the DIBH versus FB planning. For the heart and LAD parameters, all constraints evaluated favored DIBH planning, with statistical significance. Regarding the heart,  median V16.8 Gy was 2.56% in FB vs. 0% in DIBH (p &lt; 0.001); median V8.8 Gy was 3.47% in FB vs. 0% in DIBH (p &lt; 0.001) and the median of mean heart dose was 1.97 Gy in FB vs. 0.92 Gy in DIBH (p &lt; 0.001). For the LAD constraints D2% &lt; 42 Gy, the median dose was 34.87 Gy in FB versus 5.8  Gy in DIBH (p &lt; 0.001); V16.8 Gy &lt; 10%, the median was 15.87% in FB versus 0% in DIBH (p &lt; 0.001) and the median of mean LAD dose was 8.13Gy in FB versus 2.92Gy in DIBH (p &lt; 0.001). Conclusions: The DIBH technique has consistently demonstrated a significant dose reduction in the heart and LAD in all evaluated constraints, while keeping the same dose coverage in the PTV eval
    corecore