Contact transformations and the theory of optimal control

Contact transformation of independent and dependent variables of Hamilton-Jacobi equatio

Sizes of Voids as a test for Dark Matter Models

We use the void probability statistics to study the redshift-space galaxy distribution as described by a volume-limited subsample of the Perseus-Pisces survey. We compare the results with the same analysis realized on artificial samples, extracted from high-resolution N-body simulations by reproducing the observational biases of the real data set. Simulations are run for the Cold+HotDM model (CHDM) and for unbiased and biased (b=1.5) CDM models in a 50 Mpc/h box. We identify galaxies as residing in peaks of the evolved density field. We fragment overmerged structures into individual galaxies so as to reproduce both the correct luminosity function (after assuming M/ L values for the resulting galaxy groups) and the two-point correlation function. Our main result is that a void-probability function (VPF) from the standard CHDM model with fractions 60% cold, 30% hot, 10% barions, exceeds the observational VPF with a high confidence level. CDM models produce smaller VPF independent of the biasing parameter. We verify the robustness of this result against changing the observer position in the simulations and the galaxy identification in the evolved density field.Comment: 15 pages, postscrip

The clinical relevance and newsworthiness of NIHR HTA-funded research: a cohort study

ObjectiveTo assess the clinical relevance and newsworthiness of the UK National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme funded reports.Study designRetrospective cohort study.SettingThe cohort included 311 NIHR HTA Programme funded reports publishing in HTA in the period 1 January 2007–31 December 2012. The McMaster Online Rating of Evidence (MORE) system independently identified the clinical relevance and newsworthiness of NIHR HTA publications and non-NIHR HTA publications. The MORE system involves over 4000 physicians rating publications on a scale of relevance (the extent to which articles are relevant to practice) and a scale of newsworthiness (the extent to which articles contain news or something clinicians are unlikely to know).Main outcome measuresThe proportion of reports published in HTA meeting MORE inclusion criteria and mean average relevance and newsworthiness ratings were calculated and compared with publications from the same studies publishing outside HTA and non-NIHR HTA funded publications.Results286/311 (92.0%) of NIHR HTA reports were assessed by MORE, of which 192 (67.1%) passed MORE criteria. The average clinical relevance rating for NIHR HTA reports was 5.48, statistically higher than the 5.32 rating for non-NIHR HTA publications (mean difference=0.16, 95% CI 0.04 to 0.29, p=0.01). Average newsworthiness ratings were similar between NIHR HTA reports and non-NIHR HTA publications (4.75 and 4.70, respectively; mean difference=0.05, 95% CI ?0.18 to 0.07, p=0.402). NIHR HTA-funded original research reports were statistically higher for newsworthiness than reviews (5.05 compared with 4.64) (mean difference=0.41, 95% CI 0.18 to 0.64, p=0.001).ConclusionsFunding research of clinical relevance is important in maximising the value of research investment. The NIHR HTA Programme is successful in funding projects that generate outputs of clinical relevance

Experimental determination of the state-dependent enhancement of the electron-positron momentum density in solids

The state-dependence of the enhancement of the electron-positron momentum density is investigated for some transition and simple metals (Cr, V, Ag and Al). Quantitative comparison with linearized muffin-tin orbital calculations of the corresponding quantity in the first Brillouin zone is shown to yield a measurement of the enhancement of the s, p and d states, independent of any parameterizations in terms of the electron density local to the positron. An empirical correction that can be applied to a first-principles state-dependent model is proposed that reproduces the measured state-dependence very well, yielding a general, predictive model for the enhancement of the momentum distribution of positron annihilation measurements, including those of angular correlation and coincidence Doppler broadening techniques

Performance of alkaline battery cells used in emergency locator transmitters

The characteristics of battery power supplies for emergency locator transmitters (ELT's) were investigated by testing alkaline zinc/manganese dioxide cells of the type typically used in ELT's. Cells from four manufacturers were tested. The cells were subjected to simulated environmental and load conditions representative of those required for survival and operation. Battery cell characteristics that may contribute to ELT malfunctions and limitations were evaluated. Experimental results from the battery cell study are discussed, and an evaluation of ELT performance while operating under a representative worst-case environmental condition is presented

Lead Isotope Data for Gold-Bearing Veins and Their Host Metasedimentary Rocks of the Goldenville Formation, Eastern Nova Scotia

Lead isotope analyses have been determined for galenas which occur in small quantities in quartz veins in the Goldenville Formation of the Meguma Terrane, and also for five whole rock samples from this formation- The ten least radiogenic galenas are homogeneous in isotopic composition, and they plot close to the average terrestrial growth curve of Stacey and Kramers and the "orogene" curve of Doe and Zartman. The mean model ages are 550 Ma (Stacey and Kramers) and 600 Ma (Doe and Zartman), which are in approximate agreement with the Cambro-Ordovician age of deposition of the sediments. The close position of the galena compositions to these average growth curves suggests that these compositions were established by mixing processes as envisaged in the Doe and Zartman "plumbotectonics" model. The isotopic analyses of the whole rocks indicate that small amounts of radiogenic lead are present in non-mineralized sections of the sedimentary sequence- Three galenas from veins in rocks metamorphosed to biotite and staurolite-andalusite grades, and from late veins (post-dating deformation, metamorphism and plutonism) are significantly more radiogenic than the majority of the samples. We interpret the isotopic characteristics of these galenas to be the result of extraction of lead from Meguma metasediments or of additions of radiogenic lead to less radiogenic lead during remobllization. Other interpretations consistent with the isotopic data are possible. RÉSUMÉ Des analyses aux isotopes de plomb ont été déterminé pour les galènes qui se trouvent en petite quantitié's dans les veines de quartz de la formation Goldenville du terrane Meguma, et aussi pour cinq échantillons de roches entieres de cette formation. Les dix galènes les moins radiogèniques sont homogènes en composition isotopique, et elles ont une trace proche de la courbe de croissauce terreste moyenne de Stacey et Kramers, et de la courbe "orogène" de Doe et Zartman. Le âges moyens des modules sont de 550 Ma (Stacey et Kramers) et de 600 Ma (Doe et Zartman), ce qui s'accorde approximativement avec l'âge Cambro-Ordovicien du dépôt des sédiments. La position proche des compositions de la galène avec ces courbes moyennes de croissance, indique que ces compositions ont été établies par un processus de mélanges, comme le propose le modèle "Piumbotectonique" de Doe et Zartman. Les analyses isotopiques de roche entiere indiquent que de petites quantitié's de plomb radiogenique sont présences dans les sections non-minéralisees de la séquence sédimentaire. Trois galènes, provenant de veines de roches métamorphosée au dégris de biotite et de staurolite-anda lusite, et de veines avancées (post-datant la déformation, le métamorphisine et le plutonisme) sont d'une maniere significative plus radiogèniques que la majoritié des échantillons. Nous interprètons les caractéristiques isotopiques de ces galènes comme le résultat de l'extraction de plomb des méta-sédiments Meguma, ou a L’addition de plomb radiogènique au plomb moins radiogènique durant la remobilisation. D'autres Interprètations en accord avec les donnés isotopiques sont possible. [Traduit par le journal

Rotational Widths for Use in the Tully-Fisher Relation. II. The Impact of Surface Brightness

Using a large sample of spiral galaxies for which 21 cm single-dish and/or long-slit optical spectra are available, we make a detailed comparison between various estimates of rotational widths. Different optical width estimators are considered and their limitations discussed, with emphasis on biases associated with rotation curve properties (shape and extent) and disk central surface brightness. The best match with HI rotational velocities is obtained with Polyex widths, which are measured at the optical radius (encompassing a fixed fraction of the total light of the galaxy) from a model fit to the rotation curve. In contrast with Polyex widths, optical rotational velocities measured at 2.15 disk scale lengths r_d deviate from HI widths by an amount that correlates with the central surface brightness of the disk. This bias occurs because the rotation curves of galaxies are in general still rising at 2.15 r_d, and the fraction of total mass contained within this radius decreases with increasing disk surface brightness. Statistical corrections, parameterized by the radial extent of the observed rotation curve, are provided to reduce Polyex and HI width measurements into a homogeneous system. This yields a single robust estimate of rotational velocity to be used for applications of disk scaling relations.Comment: 13 pages, 8 figures. To appear in the Astronomical Journal (August 2007