autopsych : An R Shiny tool for the reproducible Rasch analysis, differential item functioning, equating, and examination of group effects

In this paper, we present autopsych, a novel online tool that allows school assessment experts, test developers, and researchers to perform routine psychometric analyses and equating of student test data and to examine the effect of student demographic and group conditions on student test performance. The app extends current open-source software by providing (1) extensive embedded result narration and summaries for written reports, (2) improved handling of partial credit data via customizable item-person Wright maps, (3) customizable item- and person-flagging systems, (4) item-response theory model constraints and controls, (5) many-facets Rasch analysis to examine item bias, (6) Rasch fixed item equating for mapping student ability across test forms, (7) tabbed spreadsheet outputs and immediate options for secondary data analysis, (8) customizable graphical color schemes, (9) extended ANOVA analysis for examining group differences, and (10) inter-rater reliability analyses for the verifying the consistency of rater scoring systems. We present the app’s architecture and functionalities and test its performance with simulated and real-world small-, medium-, and large-scale assessment data. Implications and planned future developments are also discussed

Chirality effects in carbon nanotubes

We consider chirality related effects in optical, photogalvanic and electron-transport properties of carbon nanotubes. We show that these properties of chiral nanotubes are determined by terms in the electron effective Hamiltonian describing the coupling between the electron wavevector along the tube principal axis and the orbital momentum around the tube circumference. We develop a theory of photogalvanic effects and a theory of d.c. electric current, which is linear in the magnetic field and quadratic in the bias voltage. Moreover, we present analytic estimations for the natural circular dichroism and magneto-spatial effect in the light absorption.Comment: 23 pages, 3 figure

Superconductivity in carbon nanotube ropes

We investigate the conditions in which superconductivity may develop in ropes of carbon nanotubes. It is shown that the interaction among a large number of metallic nanotubes favors the appearance of a metallic phase in the ropes, intermediate between respective phases with spin-density-wave and superconducting correlations. These arise in samples with about 100 metallic nanotubes or more, where the long-range Coulomb interaction is very effectively reduced and it may be overcome by the attractive interaction from the exchange of optical phonons within each nanotube. We estimate that the probability for the tunneling of Cooper pairs between neighboring nanotubes is much higher than that for single electrons in a disordered rope. The effect of pair hopping is therefore what establishes the intertube coherence, and the tunneling amplitude of the Cooper pairs dictates the scale of the transition to the superconducting state.Comment: 12 page

Measurements of the Production, Decay and Properties of the Top Quark: A Review

With the full Tevatron Run II and early LHC data samples, the opportunity for furthering our understanding of the properties of the top quark has never been more promising. Although the current knowledge of the top quark comes largely from Tevatron measurements, the experiments at the LHC are poised to probe top-quark production and decay in unprecedented regimes. Although no current top quark measurements conclusively contradict predictions from the standard model, the precision of most measurements remains statistically limited. Additionally, some measurements, most notably the forward-backward asymmetry in top quark pair production, show tantalizing hints of beyond-the-Standard-Model dynamics. The top quark sample is growing rapidly at the LHC, with initial results now public. This review examines the current status of top quark measurements in the particular light of searching for evidence of new physics, either through direct searches for beyond the standard model phenomena or indirectly via precise measurements of standard model top quark properties

t→bWt \to b W in NonCommutative Standard Model

We study the top quark decay to b quark and W boson in the NonCommutative Standard Model (NCSM). The lowest contribution to the decay comes from the terms quadratic in the matrix describing the noncommutative (NC) effects while the linear term is seen to identically vanish because of symmetry. The NC effects are found to be significant only for low values of the NC characteristic scale.Comment: 11 page Latex file containing 2 eps figures (redrawn). More discussion included. To appear in PR

Collider aspects of flavour physics at high Q

This review presents flavour related issues in the production and decays of heavy states at LHC, both from the experimental side and from the theoretical side. We review top quark physics and discuss flavour aspects of several extensions of the Standard Model, such as supersymmetry, little Higgs model or models with extra dimensions. This includes discovery aspects as well as measurement of several properties of these heavy states. We also present public available computational tools related to this topic.Comment: Report of Working Group 1 of the CERN Workshop ``Flavour in the era of the LHC'', Geneva, Switzerland, November 2005 -- March 200

Ion-beam excitation of liquid argon

The scintillation light of liquid argon has been recorded wavelength and time resolved with very good statistics in a wavelength interval ranging from 118 nm through 970 nm. Three different ion beams, protons, sulfur ions and gold ions, were used to excite liquid argon. Only minor differences were observed in the wavelength-spectra obtained with the different incident particles. Light emission in the wavelength range of the third excimer continuum was found to be strongly suppressed in the liquid phase. In time-resolved measurements, the time structure of the scintillation light can be directly attributed to wavelength in our studies, as no wavelength shifter has been used. These measurements confirm that the singlet-to-triplet intensity ratio in the second excimer continuum range is a useful parameter for particle discrimination, which can also be employed in wavelength-integrated measurements as long as the sensitivity of the detector system does not rise steeply for wavelengths longer than 190 nm. Using our values for the singlet-to-triplet ratio down to low energies deposited a discrimination threshold between incident protons and sulfur ions as low as ∼2.5 keV seems possible, which represents the principle limit for the discrimination of these two species in liquid argon

Volvulus du côlon sigmoïde sur grossesse : àpropos d’un cas

La survenue d'une occlusion intestinale au cours de la grossesse est rare. Il s’agit d’une association qui engage le pronostic vital maternel et foetalcar souvent source de retard diagnostique. Nous rapportons un cas de  volvulus du colon sigmoïde sur grossesse évolutive. Il s'agit d'une patiente âgée de 32 ans que nous avons reçu aux urgences pour syndrome occlusif depuis deux jours. Cette patiente était par ailleurs suivie pour une grossesse mono- foetale évolutive estimée à 32 semaines et 02 jours confirmée à l'échographie. L'examen abdominal objectivait un météorisme  important asymétrique. La radiographie de l'abdomen sans préparation était en faveur d'un volvulus du colon pelvien. Une laparotomie exploratrice a confirmée le diagnostic. Une césarienne associée à une sigmoïdectomie avec anastomose terminoterminale immédiate avaient été réalisées. Les  suites opératoires étaient simples chez la patiente et la sortie était faite au 6ème jour post-opératoire. Le nouveau-né était décédé au 5ème jour de vie d'une détresse respiratoire. Le volvulus du colon sigmoïde compliquant la grossesse est une urgence qui doit souffrir d'aucun retard diagnostique ni thérapeutique. La prise en charge doit être pluridisciplinaire entre chirurgiens, obstétriciens, anesthésistes-réanimateurs et néonatologues.L’accès à l’endoscopie en urgence pourrait améliorer le pronostic en permettant la chirurgie à froid après une bonne maturation foetale.Mots-clés : volvulus, colon sigmoïde, grossesse.The occurrence of bowel obstruction during pregnancy is rare. It is an association that has a poor prognosis for the mother and the fetus because it is often diagnosed late. We report a case of sigmoid volvulus in pregnancy. It was a 32-year-old woman who consulted in the emergency department for bowel obstruction for two days. This patient was also followed by obstetrician for an active mono-fetal pregnancy estimatedat 32 weeks and 02 days confirmed by ultrasonography. The abdominal examination showed an asymmetrical meteorism. The plain abdominalradiography radiograph found a coffee bean sign suggestive of sigmoid volvulus. An exploratory laparotomy confirmed the diagnosis. Caesarean section associated with a sigmoidectomy and immediate anastomosis were performed. Postoperative period was uneventful and the patient was discharged on the 6th day. The newborn died on the 5th day of respiratory distress. Sigmoid volvulus complicating pregnancy is an emergency. It must not suffer from any diagnostic or therapeutic delays. The management is multidisciplinary between surgeons, obstetricians, anesthetists and neonatologists. Access to emergency endoscopy may improve the prognosis by allowing surgery after good fetal maturation.Key words: volvulus, sigmoid colon, pregnancy