On the arcmin structure of the X-ray Universe

We present the angular correlation function of the X-ray population of 1063 XMM-Newton observations at high Galactic latitudes, comprising up to ~30000 sources over a sky area of ~125 sq. degrees in the energy bands: soft (0.5-2 keV) and hard (2-10 keV). This is the largest sample of serendipitous X-ray sources ever used for clustering analysis purposes to date and the results have been determined with unprecedented accuracy. We detect significant clustering signals in the soft and hard bands (~10 sigma and ~5 sigma, respectively). We deproject the angular correlation function via Limber's equation and calculate the typical spatial lengths. We infer that AGN at redshifts ~1 are embedded in dark matter halos with typical masses of log M ~ 12.6/h Msol and lifetimes in the range ~3-5 x 10^8 years, which indicates that AGN activity is a transient phase in the life of galaxies.Comment: 4 pages, 1 figure. Proc. of the conference "X-ray Astronomy 2009: Present status, multiwavelength approach and future perspectives", September 2009, Bologna. To appear in AIP Conf. Proc. (editors: A. Comastri, M. Cappi, L. Angelini)

Structural and spectroscopic characterisation of C4 oxygenates relevant to structure/activity relationships of the hydrogenation of α,β-unsaturated carbonyls

In the present work, we have investigated the conformational isomerism and calculated the vibrational spectra of the C4 oxygenates: 3-butyne-2-one, 3-butene-2-one, 2-butanone and 2-butanol using density functional theory. The calculations are validated by comparison to structural data where available and new, experimental inelastic neutron scattering and infrared spectra of the compounds. We find that for 3-butene-2-one and 2-butanol the spectra show clear evidence for the presence of conformational isomerism and this is supported by the calculations. Complete vibrational assignments for all four molecules are provided and this provides the essential information needed to generate structure/activity relationships for the sequential catalytic hydrogenation of 3-butyne-2-one to 2-butanol

Perspectives on financial incentives to health service providers for increasing breast feeding and smoking quit rates during pregnancy: a mixed methods study

Objective: To explore the acceptability, mechanisms and consequences of provider incentives for smoking cessation and breast feeding as part of the Benefits of Incentives for Breastfeeding and Smoking cessation in pregnancy (BIBS) study. Design: Cross-sectional survey and qualitative interviews. Setting: Scotland and North West England. Participants: Early years professionals: 497 survey respondents included 156 doctors; 197 health visitors/maternity staff; 144 other health staff. Qualitative interviews or focus groups were conducted with 68 pregnant/postnatal women/family members; 32 service providers; 22 experts/decision-makers; 63 conference attendees. Methods: Early years professionals were surveyed via email about the acceptability of payments to local health services for reaching smoking cessation in pregnancy and breastfeeding targets. Agreement was measured on a 5-point scale using multivariable ordered logit models. A framework approach was used to analyse free-text survey responses and qualitative data. Results: Health professional net agreement for provider incentives for smoking cessation targets was 52.9% (263/497); net disagreement was 28.6% (142/497). Health visitors/maternity staff were more likely than doctors to agree: OR 2.35 (95% CI 1.51 to 3.64; p<0.001). Net agreement for provider incentives for breastfeeding targets was 44.1% (219/497) and net disagreement was 38.6% (192/497). Agreement was more likely for women (compared with men): OR 1.81 (1.09 to 3.00; p=0.023) and health visitors/maternity staff (compared with doctors): OR 2.54 (95% CI 1.65 to 3.91; p<0.001). Key emergent themes were 'moral tensions around acceptability', 'need for incentives', 'goals', 'collective or divisive action' and 'monitoring and proof'. While provider incentives can focus action and resources, tensions around the impact on relationships raised concerns. Pressure, burden of proof, gaming, box-ticking bureaucracies and health inequalities were counterbalances to potential benefits. Conclusions: Provider incentives are favoured by non-medical staff. Solutions which increase trust and collaboration towards shared goals, without negatively impacting on relationships or increasing bureaucracy are required

Apparatus description and data analysis of a radiometric technique for measurements of spectral and total normal emittance

The development of a radiometric technique for determining the spectral and total normal emittance of materials heated to temperatures of 800, 1100, and 1300 K by direct comparison with National Bureau of Standards (NBS) reference specimens is discussed. Emittances are measured over the spectral range of 1 to 15 microns and are statistically compared with NBS reference specimens. Results are included for NBS reference specimens, Rene 41, alundum, zirconia, AISI type 321 stainless steel, nickel 201, and a space-shuttle reusable surface insulation

Developing numerical libraries in Java

The rapid and widespread adoption of Java has created a demand for reliable and reusable mathematical software components to support the growing number of compute-intensive applications now under development, particularly in science and engineering. In this paper we address practical issues of the Java language and environment which have an effect on numerical library design and development. Benchmarks which illustrate the current levels of performance of key numerical kernels on a variety of Java platforms are presented. Finally, a strategy for the development of a fundamental numerical toolkit for Java is proposed and its current status is described.Comment: 11 pages. Revised version of paper presented to the 1998 ACM Conference on Java for High Performance Network Computing. To appear in Concurrency: Practice and Experienc

NASA/RAE collaboration on nonlinear control using the F-8C digital fly-by-wire aircraft

Design procedures are reviewed for variable integral control to optimize response (VICTOR) algorithms and results of preliminary flight tests are presented. The F-8C aircraft is operated in the remotely augmented vehicle (RAV) mode, with the control laws implemented as FORTRAN programs on a ground-based computer. Pilot commands and sensor information are telemetered to the ground, where the data are processed to form surface commands which are then telemetered back to the aircraft. The RAV mode represents a singlestring (simplex) system and is therefore vulnerable to a hardover since comparison monitoring is not possible. Hence, extensive error checking is conducted on both the ground and airborne computers to prevent the development of potentially hazardous situations. Experience with the RAV monitoring and validation procedures is described

Cardiac Depression Scale: Mokken scaling in heart failure patients

Background: There is a high prevalence of depression in patients with heart failure (HF) that is associated with worsening prognosis. The value of using a reliable and valid instrument to measure depression in this population is therefore essential. We validated the Cardiac Depression Scale (CDS) in heart failure patients using a model of ordinal unidimensional measurement known as Mokken scaling. Findings: We administered in face-to-face interviews the CDS to 603 patients with HF. Data were analysed using Mokken scale analysis. Items of the CDS formed a statistically significant unidimensional Mokken scale of low strength (H&lt;0.40) and high reliability (Rho>0.8). Conclusions: The CDS has a hierarchy of items which can be interpreted in terms of the increasingly serious effects of depression occurring as a result of HF. Identifying an appropriate instrument to measure depression in patients with HF allows for early identification and better medical management. Keywords: Cardiac Depression Scale, Heart failure, Depression, Mokken scalin

Comparaison de plans d’échantillonnage séquentiel binomial et de type Iwao pour le dépistage du thrips de l’oignon (Thrips tabaci) [Thysanoptera : Thripidae] sur l’oignon

Des différences transitoires de densité du thrips de l'oignon (Thrips tabaci) ont été observées entre les bordures et le centre de certains champs d'oignon (Allium cepa). Les populations de thrips sont constituées d'agrégats dispersés de façon contagieuse à l'intérieur des champs d'oignon. Deux types de plans d'échantillonnage séquentiel ont été établis pour le T. tabaci sur l'oignon: plan binomial basé sur la présence d'au moins 5 thrips plant d'oignon-1 et plan de type Iwao nécessitant le décompte de tous les thrips présents. Les limites d'acceptation de ces plans ont été calculées pour des seuils économiques de 0,9 et 2,2 thrips feuille-1 Ces plans ont été validés dans des champs abritant des populations entre 0,01 et 32,33 thripsfeuille-1. Les plans de type binomial se sont avérés aussi fiables que les plans séquentiels avec des taux d'erreur ne dépassant jamais 4%, ce qui est inférieur aux niveaux théoriques choisis de 5 et 10%. De bonnes prises de décision ont été obtenues dans 90,4 et 83,6% des cas à l'aide des plans par décompte, et dans 84,8 et 82,4% des cas à l'aide des plans binomiaux pour les seuils de 0,9 et 2,2 thrips feuille-1, respectivement. Le nombre moyen d'échantillons à prélever pour prendre une décision oscille entre 10 et 14 plants d'oignon selon le plan employé. L'emploi des plans binomiaux peut entraîner des réductions de l'effort de comptage des thrips pouvant atteindre jusqu'à 62 et 88% pour les seuils de 0,9 et 2,2 thrips feuille-1, respectivement.Transient differences in onion thrips (Thrips tabaci) densities were observed between the margins and the centre of some onion (Allium cepa) fields. Onion thrips populations consist in aggregates contagiously dispersed within onion fields. Two types of sequential sampling plans were established for T. tabaci in onions: a binomial plan based on the presence of 5 thrips plant-1, and one of the Iwao type, requiring counts of aol thrips present. Acceptation boundaries for these plans were calculated for economic thresholds of 0.9 and 2.2 thrips leaf-1. Plans were validated in fields with thrips populations varying between 0.01 and 32.33 thrips leaf-1. E3 binomial sequential sampling plans were found to be as reliable as plans requiring counts of all thrips, with an error rate not exceeding 4%, a level below the theoretical error rates of 5 and 10% used in the calculations. Correct decisions were reached in 90.4 and 83.6% of the situations with plans requiring counts of all thrips, and in 84.8 and 82.4% of the situations with binomial plans for economic thresholds of 0.9 and 2.2 thrips leaf-1, respectively. The average number of samples needed to reach a decision varied between 10 and 14 plants according to the plan used. Use of binomial plans can save up to 62 and 88% of the counting effort for thresholds of 0.9 and 2.2 thrips leaf-1, respectively

Singularity Theory in Classical Cosmology

This paper compares recent approaches appearing in the literature on the singularity problem for space-times with nonvanishing torsion.Comment: 4 pages, plain-tex, published in Nuovo Cimento B, volume 107, pages 849-851, year 199