Reducing streak film data via electronic cross correlator

Continuous /nonframing/ motion picture projector, two photocells, a cross-correlator, and a ground glass screen where the photocells intercept the stream image determine the time delay between successive streak images. Velocities corresponding to the streaks are determined from the delay together with the distance separating the photocells

Ignorance is Almost Bliss: Near-Optimal Stochastic Matching With Few Queries

The stochastic matching problem deals with finding a maximum matching in a graph whose edges are unknown but can be accessed via queries. This is a special case of stochastic $k$-set packing, where the problem is to find a maximum packing of sets, each of which exists with some probability. In this paper, we provide edge and set query algorithms for these two problems, respectively, that provably achieve some fraction of the omniscient optimal solution. Our main theoretical result for the stochastic matching (i.e., $2$-set packing) problem is the design of an \emph{adaptive} algorithm that queries only a constant number of edges per vertex and achieves a $(1-\epsilon)$ fraction of the omniscient optimal solution, for an arbitrarily small $\epsilon>0$. Moreover, this adaptive algorithm performs the queries in only a constant number of rounds. We complement this result with a \emph{non-adaptive} (i.e., one round of queries) algorithm that achieves a $(0.5 - \epsilon)$ fraction of the omniscient optimum. We also extend both our results to stochastic $k$-set packing by designing an adaptive algorithm that achieves a $(\frac{2}{k} - \epsilon)$ fraction of the omniscient optimal solution, again with only $O(1)$ queries per element. This guarantee is close to the best known polynomial-time approximation ratio of $\frac{3}{k+1} -\epsilon$ for the \emph{deterministic} $k$-set packing problem [Furer and Yu, 2013] We empirically explore the application of (adaptations of) these algorithms to the kidney exchange problem, where patients with end-stage renal failure swap willing but incompatible donors. We show on both generated data and on real data from the first 169 match runs of the UNOS nationwide kidney exchange that even a very small number of non-adaptive edge queries per vertex results in large gains in expected successful matches

The incidence and intensity of employer-provided training

This paper examines the provision of training by employers and the participation in training by employees, conditional on employers´ training provision. Together these two dimensions of training determine its overall distribution in the workforce. The factors which affect employer training provision and employee training participation are considered simultaneously within an empirical model using data drawn primarily from the 2001 Employers Skill Survey. The results are consistent with high fixed costs but constant marginal costs of training provision, while also supporting many of the predictions regarding the relationship between training and workforce skills, skill-shortages, workplace and local labour market characteristics

Evaluating the impact of the rural dimension of specialism

Commissioned by the Specialist Schools and Academies TrustThe rural dimension is intended to offer the opportunity to schools to enhance and extend the curriculum. Its focus is the understanding of environmental issues and the countryside, and it is seen as relevant to all schools, including those in urban areas. The Specialist Schools and Academies Trust (SSAT) wishes to evaluate the extent to which the rural dimension is effective in raising standards. The aim of this study, commissioned by the SSAT, was to ascertain the extent to which the work schools undertake as part of their rural dimension has a demonstrable impact on achievement and attainment - in particular concerning: 1) attainment (pupil performance and school standards); 2) behaviour and attendance (on the part of pupils); 3) engagement (pupil interest and motivation, and raising aspirations among pupils and their families). The approach taken in the study is chiefly an interpretative and illuminative one with the aim of throwing light on how the rural dimension acts as an influence within the school context. Rather than looking for linear cause-and-effect, methodologically it was seen as more helpful to view organisations as complex processes of continual interaction in which any one initiative is the catalyst to multiple interpretations and reactions which generate further initiatives. Qualitative data are particularly helpful in throwing light on these processes. An exploratory case study approach was used, generating both qualitative and quantitative data in order to reflect the complexity of practice and experience in the rural dimension. Six case study schools were selected from rural dimension schools which expressed a wish to participate in the study. Criteria were used to maximise the variation in the sample used, although those with relatively large farms are over-represented. Each of the six case study schools was visited by one or more of the research team. Visits involved interviews, observation and perusal and collection of documentary data (including schools’ websites). This report also includes a selective literature review, highlighting some of the issues concerning research into specialisms and the value of education for sustainable development

Photographic method measures particle size and velocity in fluid stream

Method employing a nonframing motion picture camera, a continuous front light source, and a strobe light determines the size and velocity of small particles in nonturbulent fluid streams. This method is used in the study of the motion of solid and liquid particles in research and industrial fluid flow systems

The Crystal Structure of a Proposed Hinesol Intermediate

The structure of a proposed intermediate of the naturally occurring sesquiterpene hinesol was determined by X-ray analysis. The structure was solved using the heavy-atom technique and refined to an R index of 0-065 for 1739 non-zero reflections. The results of the analysis revealed that the intermediate had a structure incompatible with conversion to hinesol

The Crystal Structure of a Photodimer of 1,4-Epoxy-1,4-dihydronaphthalene

The crystal structure of a photodimer of l,4-epoxy-1,4-dihydronaphthalene, with empirical formula C_(20)H_(16)O_2, has been determined by the application of direct methods. Three-dimensional data were collected on a Datex-automated General Electric diffractometer to a minimum spacing of 1·0 Å. The coordinates of all atoms in the molecule, the isotropic temperature factors for the hydrogen atoms, and the anisotropic temperature factors for the other atoms were refined by the method of least squares. The final R index was 0·027. The crystals are orthorhombic, space group Pcɑ2_1 with ɑ = 16-52, b = 7·975 and c= 10·58 Å. Of four possible configurations, the molecule of the photodimer has the exotrans-exo configuration. Despite the lack of a center of symmetry in the space group, the molecule is centrosymmetric almost within experimental error