Two-photon imaging of cell-specific fluorophores in transgenic mice – an exploratory tool to study mechanisms of white matter injury

Relatively little is known about specific pathways leading to structural and functional disruption of axons and glial cells in white matter. Because focal cerebral ischemia in humans damages both gray and white matter, an understanding of white matter injury is important in devising potential therapeutic approaches. We have developed a novel brain slice model from transgenic mice under control of cell-specific promoters to understand interactions between oligodendrocytes and axons under high resolution twophoton microscopy. Our data extends over previous findings the vulnerability of oligodendrocytes and axons both in culture and in slice preparations to glutamate toxicity during stroke and hypoglycemia. Conditions as different as stroke, trauma, perinatal brain injury, and multiple sclerosis may share common mechanisms of white matter injury.N/

Perception of the level of difficulty by post-secondary Maltese students of the biology advanced level practical examination paper

Maltese students sit for the Matriculation and Secondary Education Certificate (MATSEC) Advanced-level biology exam at the end of a two-year ‘sixth form’ course as a requirement to pursue studies related to science at the University of Malta. The exam consists of four papers, where Paper 1 consists of compulsory structured questions, Paper 2 involves essay-writing, Paper 3 is based on practical work related to theory, and Paper 4 consists of a single experimental design question. A questionnaire based on a Likert five-point scale was administered to students (N=102) two months before they sat for the MATSEC examination. The aim was to investigate the level of difficulty that students encounter with each of the exam papers as well when answering ten typical questions presented in Paper 4. No significant difference in the difficulty rating evaluation for males and females for Paper 1, 2 and 3 was found; however females found Paper 4 significantly more difficult than males. When presented with a test at school modelled on Paper 4, males felt more confident than females however they felt equally nervous. On the other hand, females felt more panicky than males. There was no significant difference between the level of difficulty encountered in each paper and the grade obtained at ‘Ordinary’ level biology (the examination taken at the end of secondary school). Students that were repeating their ‘sixth form’ second year encountered the same level of difficulty in each paper as those who were not. The same questionnaire was administered to tutors (N=13) in order to investigate whether student and tutor perceptions differ. Students and tutors rated the level of difficulty of each paper differently. None of the tutors perceived Papers 2, 3 and 4 as ‘easy’ whereas students did. Another difference in perception was noted in Paper 1: students rated Paper 1 as ‘difficult’ while tutors did not. Students and tutors also differed in the rating of level of difficulty in Paper 4 questions. Students found the question about devising an experiment as presenting the highest level of difficulty while for tutors the most difficult was that concerned was stating the sources of error. Writing a null hypothesis presented the least difficulty for students whereas drawing graphs was rated as least difficult by tutors. These differences in perception imply that tutors may be dedicating more time preparing students for papers and questions they (the tutors) perceive as difficult and thus may not be meeting the real needs of the students.peer-reviewe

Tourism Demand in Portugal: Market Perspectives

Tourism has experienced different levels of development in the different regions of Portugal. To frame this development, several panel data models were estimated. The main objective is to explain the evolution of overnight stays by nationality in each region. Secondary data from 2000 to 2010 was used. The analysis includes the main tourism markets, such as the United Kingdom, Germany, the Netherlands, Ireland, France and Spain. Tourism literature suggests that, among others, the main determinants of tourism demand are Income (GDP), population, tourist´s income by place of residence, households’ consumption, unemployment rate, inflation rate, compensation of employees, comparative prices and households’ investment rate. It is observed that, although significant, the explanatory power of these variables varies according to the origin and the destination region considered

Perturbative and Non-perturbative Lattice Calculations for the Study of Parton Distributions

We discuss how lattice calculations can be a useful tool for the study of structure functions. Particular emphasis is given to the perturbative renormalization of the operators.Comment: 6 pages. Talk presented at the 6th International Symposium on Radiative Corrections "RADCOR 2002" and 6th Zeuthen Workshop on Elementary Particle Theory "Loops and Legs 2002", Kloster Banz (Germany), September 8 to 13, 200

The Pawns of War: A Personal Account of the Attack on Verrères Ridge by The South Saskatchewan Regiment, 20 July 1944

A number of current books deal with Operations Goodwood and Atlantic, but scant attention has been paid to the 6th Canadian Infantry Brigade and its three regiments, the Queen’s Own Cameron Highlanders of Canada (CAM), the Fusiliers Mont-Royal (FMR) and the South Saskatchewan Regiment (SSR), and to the Essex Scottish Regiment which was attached to 6th Brigade during this operation. When our role has been discussed at all, historians have inferred that the SSR fled or withdrew in panic in this action. My role was as Commander “B” Company of the SSR, and later as Acting Commanding Officer (A/CO) of the SSR during this operation. I wish to record my memories of the battle supplemented by historical documentation which I hope will cause historians to review the 6th Brigade action of 20 July 1944

Fourth Order Gradient Symplectic Integrator Methods for Solving the Time-Dependent Schr\"odinger Equation

We show that the method of splitting the operator ${\rm e}^{\epsilon(T+V)}$ to fourth order with purely positive coefficients produces excellent algorithms for solving the time-dependent Schr\"odinger equation. These algorithms require knowing the potential and the gradient of the potential. One 4th order algorithm only requires four Fast Fourier Transformations per iteration. In a one dimensional scattering problem, the 4th order error coefficients of these new algorithms are roughly 500 times smaller than fourth order algorithms with negative coefficient, such as those based on the traditional Ruth-Forest symplectic integrator. These algorithms can produce converged results of conventional second or fourth order algorithms using time steps 5 to 10 times as large. Iterating these positive coefficient algorithms to 6th order also produced better converged algorithms than iterating the Ruth-Forest algorithm to 6th order or using Yoshida's 6th order algorithm A directly.Comment: 11 pages, 2 figures, submitted to J. Chem. Phy

An experimental study of transonic flow about a supercritical airfoil. Static pressure and drag data obtained from tests of a supercritical airfoil and an NACA 0012 airfoil at transonic speeds, supplement

Surface static-pressure and drag data obtained from tests of two slightly modified versions of the original NASA Whitcomb airfoil and a model of the NACA 0012 airfoil section are presented. Data for the supercritical airfoil were obtained for a free-stream Mach number range of 0.5 to 0.9, and a chord Reynolds number range of 2 x 10 to the 6th power to 4 x 10 to the 6th power. The NACA 0012 airfoil was tested at a constant chord Reynolds number of 2 x 10 to the 6th power and a free-stream Mach number range of 0.6 to 0.8

Fermionic decays of sfermions in the MSSM: a full one-loop calculation

We present a full one-loop calculation of the electroweak corrections to the partial decay widths of the fermionic modes of sfermions \Gamma(\sfermion \to f'\chi). The main technical points of the renormalization are presented, and the main features of the results are discussed.Comment: LaTeX, 6 pages, 1 table. Talk presented at 6th International Symposium on Radiative Corrections Application of Quantum Field Theory to Phenomenology (RADCOR 2002) and 6th Zeuthen Workshop on Elementary Particle Theory Loops and Legs in Quantum Field Theory, Kloster Banz, Germany, 8-13 September, 2002, to appear in the proceeding