454 research outputs found

    A Survey on Approximation Mechanism Design without Money for Facility Games

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    In a facility game one or more facilities are placed in a metric space to serve a set of selfish agents whose addresses are their private information. In a classical facility game, each agent wants to be as close to a facility as possible, and the cost of an agent can be defined as the distance between her location and the closest facility. In an obnoxious facility game, each agent wants to be far away from all facilities, and her utility is the distance from her location to the facility set. The objective of each agent is to minimize her cost or maximize her utility. An agent may lie if, by doing so, more benefit can be obtained. We are interested in social choice mechanisms that do not utilize payments. The game designer aims at a mechanism that is strategy-proof, in the sense that any agent cannot benefit by misreporting her address, or, even better, group strategy-proof, in the sense that any coalition of agents cannot all benefit by lying. Meanwhile, it is desirable to have the mechanism to be approximately optimal with respect to a chosen objective function. Several models for such approximation mechanism design without money for facility games have been proposed. In this paper we briefly review these models and related results for both deterministic and randomized mechanisms, and meanwhile we present a general framework for approximation mechanism design without money for facility games

    Heaven and the 'basileus' in St John Chrysostom

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    The thesis takes its inspiration from a parallel central to Byzantine ideology: God enthroned in heaven, governing the universe, is mirrored on earth by the emperor surrounded by his court, ruling his realm. The earliest definitive formulation of this doctrine is expressed by Eusebius of Caesarea in the 'Tricennial Orations' held for Constantine the Great in A.D. 336. The thesis briefly documents this formulation and then takes a look at the further evolution of this parallel in some fourth century Fathers. Here the parallel becomes a metaphor in that the earthly basileus is frequently employed to explain and describe God. At the same time, the attitudes towards the earthly basileus need not be positive. After having thus set the scene, the thesis moves on to its primary task and explores heaven and the basileus in St. John Chrysostom. The sheer bulk of his work is matched by the complexity of his views in this respect, far removed from the apparent simplicity of the Eusebian model. After documenting his ideas about the technique of metaphor, and about the application of such a parallel as that of God and basileus, I examine Chrysostom's metaphorical use of the basileus in his explanations of inexprimable divine qualities. The basileus takes more shape when Chrysostom describes him in the context of the Old Testament, of early imperial history, or as a contemporary ruler. These portrayals are suitably followed by an exploration of Chrysostom's uncompromising interpretation of the relationship between priest and ruler. A short excursus on his attitude towards imperial and Christian symbols rounds off this extensive treatment of the basileus. The next two chapters concentrate on how Chrysostom describes heaven and what role is played by imperial terminology and concepts in these descriptions. Finally, the possible influence of St. Paul on Chrysostom in these areas is considered - partly because the topos of the Apostle in the power of the pagan basileus Nero appears frequently, partly because St. Paul turns out to be a major Leitfigur for Chrysostom. This bulky documentation works exclusively from texts dating from Chrysostom's life in Antioch. His move to Constantinople and into the direct environment of the real basileus presents a chronological step of the utmost importance in the context of the God - basileus parallel. Introducing this chronological divide in the course of the thesis obviously involves a close attention to the dating of Chrysostom's works, which in many cases is not unequivocal. The thesis tries to show that the awareness of a chronology of metaphorical language within Chrysostom's works can help with the dating of individual texts. Although this possibility was resorted to very sparingly here for fear of introducing a circular argument, it merits becoming a stronger element in studies on Chrysostom. For the Constantinopolitan period, the thesis tries to ascertain whether Chrysostom's view of the earthly basileus and his use of metaphors based on this basileus in the description of heaven are influenced and changed by his experience of imperial reality. The most interesting question then is to what extent Chrysostom's metaphorical use of 'the basileus' in all its different shades of meaning precipitated his fate at imperial hands. As the conclusion argues, these findings are of special interest in view of the popularity Chrysostom enjoyed throughout Byzantine history. It is possible that with his extensive metaphorical use of the basileus he was a model and an influence in theological and ideological issues. There is the possibility that descriptions that were intended by Chrysostom to show the limitations of earthly rule in comparison with heavenly power may have been misunderstood, due to subtlety of expression, as describing a full parallel between God and basileus. This applies both to contemporary audiences and later readers and supports a hypothesis that Byzantine propaganda was not so much constructed by masterminds as inferred by audiences

    Selecting Differentially Expressed Genes from Microarray Experiments

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    High throughput technologies, such as gene expression arrays and protein mass spectrometry, allow one to simultaneously evaluate thousands of potential biomarkers that distinguish different tissue types. Of particular interest here is cancer versus normal organ tissues. We consider statistical methods to rank genes (or proteins) in regards to differential expression between tissues. Various statistical measures are considered and we argue that two measures related to the Receiver Operating Characteristic Curve are particularly suitable for this purpose. We also propose that sampling variability in the gene rankings be quantified and suggest using the “selection probability function”, the probability distribution of rankings for each gene. This is estimated via the bootstrap. A real data set derived from gene expression arrays of 23 normal and 30 ovarian cancer tissues are analyzed. Simulation studies are also used to assess the relative performance of different statistical gene ranking measures and our quantification of sampling variability. Our approach leads naturally to a procedure for sample size calculations appropriate for exploratory studies that seek to identify differentially expressed genes

    Effectiveness and tolerability of radiotherapy for patients with indolent non-Hodgkin's lymphoma: a monocenter analysis

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    To analyze the effectiveness and toxicities of radiotherapy in indolent non-Hodgkin's lymphoma (iNHL) patients treated in our institution. Patients with iNHL treated with radiotherapy between 1999 and 2016 were included. The primary endpoint was progression-free survival (PFS). Secondary endpoints were local control (LC), overall survival (OS) and toxicities. PFS, LC, and OS were analyzed using Kaplan-Meier method. Log-rank test was used to investigate the differences between subgroups. Cox proportional hazard model was used for univariate continuous analysis. Seventy-five patients were identified in our institutional database between 1999 and 2016. Fifty-eight (77.3%) had stage I after Ann-Arbor and 17 patients (22.7%) had stage II. The median follow-up was 87~months (95% CI 72-102~months). Median single dose per fraction was 2.0~Gy (range 1.5-2~Gy) and median total dose was 30.6~Gy (range 16-45~Gy). Radiotherapy was performed in 2D (n = 10; 13.3%), 3D (n = 63; 84.0%) and VMAT (n = 2; 2.7%) techniques, respectively. The median PFS was 14.0~years (95% CI 8.3-19.7~years). The estimated PFS after 5 and 10~years were 73.0% and 65.5% in Kaplan-Meier analysis, respectively. The 5- and 10-year LC were 94.9% and 92.3%, respectively. The 5- and 10-year OS were 88.6% and 73.9%. In univariate analyses of PFS, younger patients (≤ 60~years old) had significantly superior PFS to those older than 60~years old (5-year PFS 81.9% vs. 65.1%, p = 0.021). Dose escalation > 36.0~Gy had no prognostic influence in term of PFS (p = 0.425). Extranodal involvement, stage and histology had no prognostic impact on PFS. Depending on the site of lymphomas, the most common acute side effects were: dermatitis CTCAE° I-II (8.0%), xerostomia CTC° I (8.0%), cataract CTC° I (12.0%) and dry eyes CTC° I-II (14.6%). No adverse event CTC° III was reported. Most acute side effects recovered at 3 to 6~months after radiotherapy except for CTC° I cataract and xerostomia. Local Radiotherapy was highly effective for treatment of early stage iNHL with no serious side effects in our cohort. The most acute CTCAE° I-II side effects recovered 3 to 6~months later. Technique advances seem to have further improved effectiveness and tolerability of radiotherapy.Trial registration: Local ethics committee of Ludwig-Maximilian-University (LMU) Munich approved this retrospective analysis on the May 7th, 2019 (Nr. 19-137)

    Collaboration in sensor network research: an in-depth longitudinal analysis of assortative mixing patterns

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    Many investigations of scientific collaboration are based on statistical analyses of large networks constructed from bibliographic repositories. These investigations often rely on a wealth of bibliographic data, but very little or no other information about the individuals in the network, and thus, fail to illustrate the broader social and academic landscape in which collaboration takes place. In this article, we perform an in-depth longitudinal analysis of a relatively small network of scientific collaboration (N = 291) constructed from the bibliographic record of a research center involved in the development and application of sensor network and wireless technologies. We perform a preliminary analysis of selected structural properties of the network, computing its range, configuration and topology. We then support our preliminary statistical analysis with an in-depth temporal investigation of the assortative mixing of selected node characteristics, unveiling the researchers' propensity to collaborate preferentially with others with a similar academic profile. Our qualitative analysis of mixing patterns offers clues as to the nature of the scientific community being modeled in relation to its organizational, disciplinary, institutional, and international arrangements of collaboration.Comment: Scientometrics (In press

    Longitudinal Analysis of Quality of Life, Clinical, Radiographic, Echocardiographic, and Laboratory Variables in Dogs with Preclinical Myxomatous Mitral Valve Disease Receiving Pimobendan or Placebo: The EPIC Study

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    Background: Changes in clinical variables associated with the administration of pimobendan to dogs with preclinical myxomatous mitral valve disease (MMVD) and cardiomegaly have not been described. Objectives: To investigate the effect of pimobendan on clinical variables and the relationship between a change in heart size and the time to congestive heart failure (CHF) or cardiac-related death (CRD) in dogs with MMVD and cardiomegaly. To determine whether pimobendan-treated dogs differ from dogs receiving placebo at onset of CHF. Animals: Three hundred and fifty-four dogs with MMVD and cardiomegaly. Materials and Methods: Prospective, blinded study with dogs randomized (ratio 1:1) to pimobendan (0.4-0.6 mg/kg/d) or placebo. Clinical, laboratory, and heart-size variables in both groups were measured and compared at different time points (day 35 and onset of CHF) and over the study duration. Relationships between short-term changes in echocardiographic variables and time to CHF or CRD were explored. Results: At day 35, heart size had reduced in the pimobendan group:median change in (Delta) LVIDDN -0.06 (IQR:-0.15 to + 0.02), P < 0.0001, and LA:Ao -0.08 (IQR:-0.23 to + 0.03), P < 0.0001. Reduction in heart size was associated with increased time to CHF or CRD. Hazard ratio for a 0.1 increase in Delta LVIDDN was 1.26, P = 0.0003. Hazard ratio for a 0.1 increase in Delta LA:Ao was 1.14, P = 0.0002. At onset of CHF, groups were similar. Conclusions and Clinical Importance: Pimobendan treatment reduces heart size. Reduced heart size is associated with improved outcome. At the onset of CHF, dogs treated with pimobendan were indistinguishable from those receiving placebo

    Global Ethics and Nanotechnology: A Comparison of the Nanoethics Environments of the EU and China

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    The following article offers a brief overview of current nanotechnology policy, regulation and ethics in Europe and The People’s Republic of China with the intent of noting (dis)similarities in approach, before focusing on the involvement of the public in science and technology policy (i.e. participatory Technology Assessment). The conclusions of this article are, that (a) in terms of nanosafety as expressed through policy and regulation, China PR and the EU have similar approaches towards, and concerns about, nanotoxicity—the official debate on benefits and risks is not markedly different in the two regions; (b) that there is a similar economic drive behind both regions’ approach to nanodevelopment, the difference being the degree of public concern admitted; and (c) participation in decision-making is fundamentally different in the two regions. Thus in China PR, the focus is on the responsibility of the scientist; in the EU, it is about government accountability to the public. The formulation of a Code of Conduct for scientists in both regions (China PR’s predicted for 2012) reveals both similarity and difference in approach to nanotechnology development. This may change, since individual responsibility alone cannot guide S&T development, and as public participation is increasingly seen globally as integral to governmental decision-making

    Sea Turtles and Survivability in Demersal Trawl Fisheries: Do Comatose Olive Ridley Sea Turtles Survive Post-Release?

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    Incidental capture of air‑breathing species in fishing gear is a major source of mortality for many threatened populations. Even when individuals are discarded alive, they may not survive due to direct injury, or due to more cryptic internal physiological injury such as decompression sickness. Post‑release mortality, however, can be difficult to determine. In this pilot study, we deployed survivorship pop‑up archival tags (sPAT) (n = 3) for an air‑breathing species, the olive ridley sea turtle (Lepidochelys olivacea), one of the first studies to do so. We found that at least two of the three turtles survived after being captured in demersal fish trawl nets and being resuscitated from a comatose state following standard UN Food and Agriculture Organization guidelines. One turtle died; however, the absence of a change in light level but continued diving activity suggested that the turtle was likely predated. Whether capture contributed to the turtle’s susceptibility to predation post‑release is unknown, and average tow duration during this fishing trip was similar in duration to that of a turtle that survived (1.5 h). The two surviving turtles displayed normal horizontal and vertical movements based on previous tagging studies. This study suggests that resuscitation techniques may be effective; however, additional study is necessary to increase sample sizes, and to determine the severity of decompression sickness across different levels of activity and in other fishing gears. This will result in better population mortality estimates, as well as highlight techniques to increase post‑release survivorship

    Proteomic Analysis of Ovarian Cancer Cells Reveals Dynamic Processes of Protein Secretion and Shedding of Extra-Cellular Domains

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    Background: Elucidation of the repertoire of secreted and cell surface proteins of tumor cells is relevant to molecular diagnostics, tumor imaging and targeted therapies. We have characterized the cell surface proteome and the proteins released into the extra-cellular milieu of three ovarian cancer cell lines, CaOV3, OVCAR3 and ES2 and of ovarian tumor cells enriched from ascites fluid. Methodology and Findings: To differentiate proteins released into the media from protein constituents of media utilized for culture, cells were grown in the presence of [ 13 C]-labeled lysine. A biotinylation-based approach was used to capture cell surface associated proteins. Our general experimental strategy consisted of fractionation of proteins from individual compartments followed by proteolytic digestion and LC-MS/MS analysis. In total, some 6,400 proteins were identified with high confidence across all specimens and fractions. Conclusions and Significance: Protein profiles of the cell lines had substantial similarity to the profiles of human ovarian cancer cells from ascites fluid and included protein markers known to be associated with ovarian cancer. Proteomic analysis indicated extensive shedding from extra-cellular domains of proteins expressed on the cell surface, and remarkably high secretion rates for some proteins (nanograms per million cells per hour). Cell surface and secreted proteins identified by indept

    Entanglement of Imaging and Imagining of Nanotechnology

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    Images, ranging from visualizations of the nanoscale to future visions, abound within and beyond the world of nanotechnology. Rather than the contrast between imaging, i.e. creating images that are understood as offering a view on what is out there, and imagining, i.e. creating images offering impressions of how the nanoscale could look like and images presenting visions of worlds that might be realized, it is the entanglement between imaging and imagining which is the key to understanding what images do. Three main arenas of entanglement of imag(in)ing and the tensions involved are discussed: production practices and use of visualizations of the nanoscale; imag(in)ing the future and the present; and entanglements of nanoscience and art. In these three arenas one sees struggles about which images might stand for nanotechnology, but also some stabilization of the entanglement of imag(in)ing, for example in established rules in the practices of visualizing the nanoscale. Three images have become iconic, through the combination of their wide reception and further circulation. All three, the IBM logo, the Foresight Institute’s Nanogear image, and the so-called Nanolouse, depict actual or imagined technoscientific objects and are thus seen as representing technoscientific achievements – while marking out territory
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