Inter-dimensional Degeneracies in van der Waals Clusters and Quantum Monte Carlo Computation of Rovibrational States

Quantum Monte Carlo estimates of the spectrum of rotationally invariant states of noble gas clusters suggest inter-dimensional degeneracy in $N-1$ and $N+1$ spacial dimensions. We derive this property by mapping the Schr\"odinger eigenvalue problem onto an eigenvalue equation in which $D$ appears as a continuous variable. We discuss implications for quantum Monte Carlo and dimensional scaling methods

Muppets and gazelles: political and methodological biases in entrepreneurship research

Despite an almost universally accepted belief outside academia that entrepreneurial activity is a positive driving force in the economy, the accumulated evidence remains largely inconclusive. This article positions the increased interest in entrepreneurship since the 1980s within its historical context and highlights the significant methodological problems with its analysis. Taking these problems into account it reevaluates the performance of entrepreneurial firms in terms of innovation, job creation, economic growth, productivity growth, and happiness to show how both positive and negative interpretations can emerge. A pattern of increasingly positive interpretation is observed as one moves from analysis to policy. To address this bias, the article suggests the single category “entrepreneurial firms” be broken up along a continuum from the large number of economically marginal, undersized, poor performance enterprises to the small number of high performance “gazelles” that drive most positive impact on the economy. This would allow a more realistic evaluation of the impact of entrepreneurs by avoiding a composition fallacy that assigns the benefits of entrepreneurship to the average firm

Universal Dynamics of Independent Critical Relaxation Modes

Scaling behavior is studied of several dominant eigenvalues of spectra of Markov matrices and the associated correlation times governing critical slowing down in models in the universality class of the two-dimensional Ising model. A scheme is developed to optimize variational approximants of progressively rapid, independent relaxation modes. These approximants are used to reduce the variance of results obtained by means of an adaptation of a quantum Monte Carlo method to compute eigenvalues subject to errors predominantly of statistical nature. The resulting spectra and correlation times are found to be universal up to a single, non-universal time scale for each model

The security implications of geoengineering:blame,imposed agreement and the security of critical infrastructure

The prospect of solar geoengineering in response to climate change (on the basis of its supposedly significantly lower cost and/or more rapid impact on global temperature than carbon reduction strategies) raises a number of security concerns that have traditionally been understood within a standard Geo-political framing of security. This relates to unrealistic direct application in inter-State warfare or to a securitization of climate change. However, indirect security implications are potentially significant. Current capability, security threats and international law loopholes suggest the military, rather than scientists would undertake geoengineering, and solar radiation management (SRM) in particular. SRM activity would be covered by Critical National Infrastructure policies, and as such would require a significant level of secondary security infrastructure. Concerns about termination effects, the need to impose international policy agreement 4 (given the ability of 'rogue States' to disrupt SRM and existing difficulties in producing global agreement on climate policy), and a world of extreme weather events, where weather is engineered and hence blameworthy rather than natural, suggest these costs would be large. Evidence on how blame is attributed suggest blame for extreme weather events may be directed towards more technologically advanced nations, (such as the USA) even if they are not engaged in geoengineering. From a security perspective SRM is costly, ungovernable, and raises security concerns of a sufficient magnitude to make it a non-viable policy option

The role of the GI radiographer: A UK perspective

Context: Since the 1990s radiographers in the United Kingdom have expanded their role in gastrointestinal (GI) radiology, first by performing double-contrast barium enema (DCBE) examinations independently and later by interpreting and reporting the results of these exams. Objective: This article will trace the evolution of GI radiographers in the United Kingdom, evaluate their success and explore how the U.K. experience could apply to American radiologist assistants. Methods: The authors surveyed the professional literature to determine the historical context in which GI radiographers emerged and assess how their performance on DCBE exams compares with radiologists’ performance. Results: DCBE exams performed by GI radiographers have been shown to be efficient, cost effective and safe. In addition, GI radiographers have helped reduce waiting and turnaround times for DCBE exams. Summary: The success of GI radiographers in the United Kingdom offers assurance that radiologist assistants can benefit American patients, radiologists and radiologic technologists

Automotive Stirling engine: Mod 2 design report

The design of an automotive Stirling engine that achieves the superior fuel economy potential of the Stirling cycle is described. As the culmination of a 9-yr development program, this engine, designated the Mod 2, also nullifies arguments that Stirling engines are heavy, expensive, unreliable, demonstrating poor performance. Installed in a General Motors Chevrolet Celebrity car, this engine has a predicted combined fuel economy on unleaded gasoline of 17.5 km/l (41 mpg)- a value 50% above the current vehicle fleet average. The Mod 2 Stirling engine is a four-cylinder V-drive design with a single crankshaft. The engine is also equipped with all the controls and auxiliaries necessary for automotive operation

Ten Key Findings From Responsible Fatherhood Initiatives

Fatherhood is crucial to child development and presents challenges to poor unmarried men. Yet services addressing these problems are not highly developed or widespread, and program results so far have been mixed. This paper analyzes five programs that support low-income noncustodial fathers and presents takeaway lessons