The direct evaluation of attosecond chirp from a streaking measurement

We derive an analytical expression, from classical electron trajectories in a laser field, that relates the breadth of a streaked photoelectron spectrum to the group-delay dispersion of an isolated attosecond pulse. Based on this analytical expression, we introduce a simple, efficient and robust procedure to instantly extract the attosecond pulse's chirp from the streaking measurement.Comment: 4 figure

Exclusionary Discipline Highest in New Hampshire’s Urban Schools Suspension and Expulsion Found to Disproportionately Affect Disadvantaged Students

This research brief follows up on a joint Carsey/NH Kids Count publication from 2009. The 2009 study focused on larger disciplinary trends in New Hampshire schools and contextualized them in the policies, laws, and procedures that may have resulted in increased use of exclusionary discipline. The present study reports on rates of exclusionary discipline from 2010 through 2014 by school and student characteristics to better understand how and to what extent exclusionary discipline has been applied across the state in recent years. Authors Douglas Gagnon, Eleanor Jaffee, and Reeve Kennedy report that although rates of out-of-school suspension among secondary school students in New Hampshire are nearly as high as national trends, rates of expulsion are far below the national average. In urban secondary schools, the rate of in-school suspension is twice that of non-urban schools, while out-of-school suspension rates are three times higher. Male students, students of color, students eligible for free or reduced-price lunch, students with disabilities, and homeless students are more likely to experience exclusionary school discipline, although racial disparities appear to stem largely from the greater racial diversity at the urban schools that use this type of discipline at higher rates with all students. Statewide, 3.5 percent of New Hampshire’s middle and high school students are suspended out of school for a total of five days or more and/or expelled in a given year. Given the notably higher rates of use of exclusionary discipline in New Hampshire’s urban school districts, the authors recommend that school policies and environments be assessed for opportunities to reverse these trends and provide more students with consistent classroom time and instruction

Température minimale au niveau du sol

L'auteur étudie la relation entre les températures minimales relevées sous abri et près du sol, en 1965 et 1966, dans 18 stations du Québec, de mai à novembre.Comme il existe une excellente corrélation (0.96) entre les deux séries de températures mesurées dans un site donné, il suffit de relever un nombre restreint de températures au sol pour avoir des renseignements statistiques valides ; cependant il faut prendre garde a la forte variation des écarts moyens d'un site à l'autre, ainsi que le montre un tableau détaillé des 18 stations employées.The author studies the relationship between the minimum temperatures recorded in a standard meteorological shelter and the corresponding minimum temperature near the ground surface for 18 stations in Québec from May to November, 1965 and 1966.Since there is an excellent correlation (0.96) between the two series of temperatures for a given site, only a limited number of measurements need be taken near the surface, in order to obtain information which is statistically significant ; however, care must be taken, since the mean deviations vary greatly from site to site, as is shown by the table of detailed results for the 18 stations studied

The Perspective and Practice of Leadership by Managers Within the Virginia Department of Corrections: An Instrumental Case Study

This dissertation explores the extent to which the perspective and practice of leadership by managers in the Virginia Department of Corrections (DOC) reflect the Leadership Perspectives Model (LPM), and the extent to which their perspective varies by level of management. The LPM is a model of leadership that consolidates leadership study into five distinct leadership perspectives that managers use in their understanding and practice of leadership. This study builds upon research in which the a LPM was tested and validated within a sample managers from municipal government agencies (M. R. Fairholm, 2004a, 2004b). The findings of this study reveal that the perspective and practice of leadership by managers at DOC only partially reflect the LPM. In addition, there is only minimal evidence that leadership perspective varies substantially based on level of management. The model was modified based on findings in this study and the modified model shows promise for increasing the overall strength and utility of the model

Results for the response function determination of the Compact Neutron Spectrometer

The Compact Neutron Spectrometer (CNS) is a Joint European Torus (JET) Enhancement Project, designed for fusion diagnostics in different plasma scenarios. The CNS is based on a liquid scintillator (BC501A) which allows good discrimination between neutron and gamma radiation. Neutron spectrometry with a BC501A spectrometer requires the use of a reliable, fully characterized detector. The determination of the response matrix was carried out at the Ion Accelerator Facility (PIAF) of the Physikalisch-Technische Bundesanstalt (PTB). This facility provides several monoenergetic beams (2.5, 8, 10, 12 and 14 MeV) and a 'white field'(Emax ~17 MeV), which allows for a full characterization of the spectrometer in the region of interest (from ~1.5 MeV to ~17 MeV. The energy of the incoming neutrons was determined by the time of flight method (TOF), with time resolution in the order of 1 ns. To check the response matrix, the measured pulse height spectra were unfolded with the code MAXED and the resulting energy distributions were compared with those obtained from TOF. The CNS project required modification of the PTB BC501A spectrometer design, to replace an analog data acquisition system (NIM modules) with a digital system developed by the 'Ente per le Nuove tecnologie, l'Energia e l'Ambiente' (ENEA). Results for the new digital system were evaluated using new software developed specifically for this project.Comment: Proceedings of FNDA 201

Experimental phase diagram of moving vortices

In the mixed state of type II superconductors, vortices penetrate the sample and form a correlated system due to the screening of supercurrents around them. Interestingly, we can study this correlated system as a function of density and driving force. The density, for instance, is controlled by the magnetic field, B, whereas a current density j acts as a driving force F=jxB on all vortices. The free motion of vortices is inhibited by the presence of an underlying potential, which tends to pin the vortices. Hence, to minimize the pinning strength we studied a superconducting glass in which the depinning current is 10 to 1000 times smaller than in previous studies, which enables us to map out the complete phase diagram in this new regime. The diagram is obtained as a function of B, driving current and temperature and led a remarkable set of new results, which includes a huge peak effect, an additional reentrant depinning phase and a driving force induced pinning phase.Comment: 4 page