Space

A wireless sensor network (WSN)consisting of a large number of tiny sensors can be an effective tool for gathering data in diverse kinds of environments. The data collected by each sensor is communicated to the base station, which forwards the data to the end user. Clustering is introduced to WSNs because it has proven to be an effective approach to provide better data aggregation and scalability for large WSNs. Clustering also conserves the limited energy resources of the sensors. This paper synthesises existing clustering algorithms news's and highlights the challenges in clustering.

This article presents results from the first statistically significant study of cost escalation in transportation infrastructure projects. Based on a sample of 258 transportation infrastructure projects worth US$90 billion and representing different project types, geographical regions, and historical periods, it is found with overwhelming statistical significance that the cost estimates used to decide whether such projects should be built are highly and systematically misleading. Underestimation cannot be explained by error and is best explained by strategic misrepresentation, that is, lying. The policy implications are clear: legislators, administrators, investors, media representatives, and members of the public who value honest numbers should not trust cost estimates and cost-benefit analyses produced by project promoters and their analysts.

We study the large volume limit of the scalar potential in Calabi-Yau flux compactifications of type IIB string theory. Under general circumstances there exists a limit in which the potential approaches zero from below, with an associated non-supersymmetric AdS minimum at exponentially large volume. Both this and its de Sitter uplift are tachyon-free, thereby fixing all Kahler and complex structure moduli, which has been difficult to achieve in the KKLT scenario. Also, for the class of vacua described in this paper, the gravitino mass is independent of the flux discretuum, whereas the ratio of the string scale to the 4d Planck scale is hierarchically small but flux dependent. The inclusion of alpha' corrections plays a crucial role in the structure of the potential. We illustrate these ideas through explicit computations for a particular Calabi-Yau manifold.

Hepatocellular carcinoma (HCC) has limited treatment options; long-term outcomes following intra-arterial radiation are unknown. We assessed clinical outcomes of patients treated with intra-arterial yttrium-90 microspheres (Y90).Patients with HCC (n = 291) were treated with Y90 as part of a single-center, prospective, longitudinal cohort study. Toxicities were recorded using the Common Terminology Criteria version 3.0. Response rate and time to progression (TTP) were determined using World Health Organization (WHO) and European Association for the Study of the Liver (EASL) guidelines. Survival by stage was assessed. Univariate/multivariate analyses were performed.A total of 526 treatments were administered (mean, 1.8; range, 1–5). Toxicities included fatigue (57%), pain (23%), and nausea/vomiting (20%); 19% exhibited grade 3/4 bilirubin toxicity. The 30-day mortality rate was 3%. Response rates were 42% and 57% based on WHO and EASL criteria, respectively. The overall TTP was 7.9 months (95% confidence interval, 6–10.3). Survival times differed between patients with Child–Pugh A and B disease (A, 17.2 months; B, 7.7 months; P = .002). Patients with Child–Pugh B disease who had portal vein thrombosis (PVT) survived 5.6 months (95% confidence interval, 4.5–6.7). Baseline age; sex; performance status; presence of portal hypertension; tumor distribution; levels of bilirubin, albumin, and α-fetoprotein; and WHO/EASL response rate predicted survival.Patients with Child–Pugh A disease, with or without PVT, benefited most from treatment. Patients with Child–Pugh B disease who had PVT had poor outcomes. TTP and overall survival varied by patient stage at baseline. These data can be used to design future Y90 trials and to describe Y90 as a potential treatment option for patients with HCC.

The Seventeen Contradictions is an x-ray of tensions, trends and tendencies in capital and capitalism that empowers us to look forward. Taking the still ongoing 2008 economic crisis as a starting point, Harvey investigates how the capitalist economy that produces such crises is embedded in contradictions. Seventeen of these are discussed throughout the book.

This article presents results from the first statistically significant study of traffic forecasts in transportation infrastructure projects. The sample used is the largest of its kind, covering 210 projects in 14 nations worth U.S.$59 billion. The study shows with very high statistical significance that forecasters generally do a poor job of estimating the demand for transportation infrastructure projects. For 9 out of 10 rail projects, passenger forecasts are overestimated; the average overestimation is 106%. For half of all road projects, the difference between actual and forecasted traffic is more than ±20%. The result is substantial financial risks, which are typically ignored or downplayed by planners and decision makers to the detriment of social and economic welfare. Our data also show that forecasts have not become more accurate over the 30-year period studied, despite claims to the contrary by forecasters. The causes of inaccuracy in forecasts are different for rail and road projects, with political causes playing a larger role for rail than for road. The cure is transparency, accountability, and new forecasting methods. The challenge is to change the governance structures for forecasting and project development. Our article shows how planners may help achieve this.

The central focus of this paper is the notion that the home can provide a locale in which people can work at attaining a sense of ontological security in a world that at times is experienced as threatening and uncontrollable. The paper builds on and develops the ideas of Giddens ...

The dynamics of ecological systems include a bewildering number of biotic interactions that unfold over a vast range of spatial scales. Here, employing simple and general empirical arguments concerning the nature of movement, trophic position and behaviour we outline a general theory concerning the role of space and food web structure on food web stability. We argue that consumers link food webs in space and that this spatial structure combined with relatively rapid behavioural responses by consumers can strongly influence the dynamics of food webs. Employing simple spatially implicit food web models, we show that large mobile consumers are inordinately important in determining the stability, or lack of it, in ecosystems. More specifically, this theory suggests that mobile higher order organisms are potent stabilizers when embedded in a variable, and expansive spatial structure. However, when space is compressed and higher order consumers strongly couple local habitats then mobile consumers can have an inordinate destabilizing effect. Preliminary empirical arguments show consistency with this general theory.

The article first describes characteristics of major infrastructure projects. Second, it documents a much neglected topic in economics: that ex ante estimates of costs and benefits are often very different from actual ex post costs and benefits. For large infrastructure projects the consequences are cost overruns, benefit shortfalls, and the systematic underestimation of risks. Third, implications for cost–benefit analysis are described, including that such analysis is not to be trusted for major infrastructure projects. Fourth, the article uncovers the causes of this state of affairs in terms of perverse incentives that encourage promoters to underestimate costs and overestimate benefits in the business cases for their projects. But the projects that are made to look best on paper are the projects that amass the highest cost overruns and benefit shortfalls in reality. The article depicts this situation as ‘survival of the unfittest’. Fifth, the article sets out to explain how the problem may be solved, with a view to arriving at more efficient and more democratic projects, and avoiding the scandals that often accompany major infrastructure investments. Finally, the article identifies current trends in major infrastructure development. It is argued that a rapid increase in stimulus spending, combined with more investments in emerging economies, combined with more spending on information technology is catapulting infrastructure investment from the frying pan into the fire.

Thermal history of droplets associated with gas atomization of melt has been investigated. A mathematical model, based on classical theory of heterogeneous nucleation and volume separation of nucleants among droplets size distribution, is described to predict undercooling of droplets. Newtonian heat flow condition coupled with velocity dependent heat transfer coefficient is used to obtain cooling rate before and after nucleation of droplets. The results indicate that temperature profile of droplets in the spray during recalescence, segregated and eutectic solidification regimes is dependent on their size and related undercooling. The interface temperature during solidification of undercooled droplets rapidly approaches the liquidus temperature of the alloy with a subsequent decrease in solid-liquid interface velocity. A comparison in cooling rates of atomized powder particles estimated from secondary dendrite arm spacing measurements are observed to be closer to those predicted from the model during segregated solidification regime of large size droplets.

This paper focuses on problems and their causes and cures in policy and planning for large-infrastructure projects. First, it identifies as the main problem in major infrastructure developments pervasive misinformation about the costs, benefits, and risks involved. A consequence of misinformation is cost overruns, benefit shortfalls, and waste. Second, it explores the causes of misinformation and finds that political-economic explanations best account for the available evidence: planners and promoters deliberately misrepresent costs, benefits, and risks in order to increase the likelihood that it is their projects, and not those of their competition, that gain approval and funding. This results in the ‘survival of the unfittest’, in which often it is not the best projects that are built, but the most misrepresented ones. Finally, it presents measures for reforming policy and planning for large-infrastructure projects with a focus on better planning methods and changed governance structures, the latter being more important.

... RHESSI has obtained the first high-resolution measurement of the positron annihilation line (Share et al. 2003b). ... Although there is a coronal source present at this time, perhaps above the loop top, it is a superhot thermal source, unlike the nonthermal source of Masuda et al. ...

A major source of risk in project management is inaccurate forecasts of project costs, demand, and other impacts. The paper presents a promising new approach to mitigating such risk, based on theories of decision making under uncertainty which won the 2002 Nobel prize in economics. First, the paper documents inaccuracy and risk in project management. Second, it explains inaccuracy in terms of optimism bias and strategic misrepresentation. Third, the theoretical basis is presented for a promising new method called "reference class forecasting," which achieves accuracy by basing forecasts on actual performance in a reference class of comparable projects and thereby bypassing both optimism bias and strategic misrepresentation. Fourth, the paper presents the first instance of practical reference class forecasting, which concerns cost forecasts for large transportation infrastructure projects. Finally, potentials for and barriers to reference class forecasting are assessed.

At the end of March 2004, the blazar S5 0716+714 underwent an optical outburst that prompted for quasi-simultaneous target-of-opportunity observations with the INTEGRAL and XMM-Newton satellites. In this paper, we report the results of the XMM-Newton and INTEGRAL OMC data analysis. The X-ray spectrum is well-represented by a concave broken power-law model, with the break at about 2 keV. In the framework of the synchrotron self-Compton model, the softer part of the spectrum, which is described by a power law of index $\alpha \simeq 1.8$ ($f_\nu \propto \nu^{-\alpha}$), is probably due to synchrotron emission, while the harder part of the spectrum, which has $\alpha \simeq 1$, is due to inverse Compton emission. The blazar shows the long and short-term variability typical of low-frequency peaked BL Lac (LBL): the former is manifested by a gradual decrease in the optical flux from the peak as observed by ground telescopes at the end of March 2004, while the latter is characterized by soft X-ray and optical flares on time scales from a few thousand seconds to few hours. We can follow spectral variations on sub-hour time scales and study their correlation with the flux variability. We find evidence that the peak energy of the time-resolved spectra is increasing with flux. The modeling of the spectral energy distribution compared with archival observations suggests that the long-term variability (from outburst to quiescence or viceversa) could be due to a change in the injected power, while the short-term variability (flares) could be explained with changes in the slope of the distribution of the electrons.

"Over budget, over time, over and over again" appears to be an appropriate slogan for large, complex infrastructure projects. This article explains why cost, benefits, and time forecasts for such projects are systematically over-optimistic in the planning phase. The underlying reasons for forecasting errors are grouped into three categories: delusions or honest mistakes; deceptions or strategic manipulation of information or processes; or bad luck. Delusion and deception have each been addressed in the management literature before, but here they are jointly considered for the first time. They are specifically applied to infrastructure problems in a manner that allows both academics and practitioners to understand and implement the suggested corrective procedures. The article provides a framework for analyzing the relative explanatory power of delusion and deception. It also suggests a simplified framework for analyzing the complex principal-agent relationships that are involved in the approval and construction of large infrastructure projects, which can be used to improve forecasts. Finally, the article illustrates reference class forecasting, an outside view de-biasing technique that has proven successful in overcoming both delusion and deception in private and public investment decisions.

In this article, I propose five ways to move beyond the analytical scheme of James Scott's Seeing Like a State (1998). I question the spatial optic that posits an “up there,” all-seeing state operating as a preformed repository of power, spread progressively outward to “nonstate” spaces beyond its reach. I highlight the role of parties beyond “the state” that attempt to govern—social reformers, scientists, and the so-called nongovernmental agencies, among others. I look beyond authoritarian high modernism to the more general problematic of “improvement” emerging from a governmental rationality focused on the welfare of populations. I explore the recourse to mētis (contextualized, local knowledge and practice) situated beyond the purview of planning. Finally, I reframe the question posed by Scott—why have certain schemes designed to improve the human condition failed?—to examine the question posed so provocatively by James Ferguson: What do these schemes do? What are their messy, contradictory, conjunctural effects?

Solid Earth–atmosphere interactions and possibly solid Earth–seafloor interactions prior to major earthquakes are the subject of this study. Using data from Moderate Resolution Imaging Spectroradiometer (MODIS) onboard National Aeronautical Space Agency (NASA) Terra and Aqua satellites, ...