Ultrashort intense-field optical vortices produced with laser-etched mirrors

We introduce a simple and practical method to create ultrashort intense optical vortices for applications involving high-intensity lasers. Our method utilizes femtosecond laser pulses to laser-etch grating lines into laser-quality gold mirrors. These grating lines holographically encode an optical vortex. We derive mathematical equations for each individual grating line to be etched, for any desired (integer) topological charge. We investigate the smoothness of the etched grooves. We show that they are smooth enough to produce optical vortices with an intensity that is only a few percent lower than in the ideal case. We demonstrate that the etched gratings can be used in a folded version of our 2f-2f setup [Mariyenko et al., Opt. Express 19, 7599 (2005)] to compensate angular dispersion. Lastly, we show that the etched gratings withstand intensities of up to 10^12 W/cm2.Comment: 14 pages, 12 figures, submitted to Optics Expres

Board composition, process, and activism: evidence within American firms

This study provided an empirical test of the effects of compositional and process variables on board activism. The attributes examined were functional area knowledge, independence, duality, and effort norms. The findings from this study provided support for the positive relationships between both functional area knowledge and effort norms and board activism. The strong relationship between effort norms and activism indicates the importance of process variables in board research and the need for additional research using process variables in a board context giving further insight into board activism and governance. Additionally, the relationship between functional area knowledge and board activism highlights how boards ability to meet cognitive demands is critical in board performance. These results as well as future research directions are examined in the discussion.board activism, board governance, board attributes, strategic management.

Intense-Field Ionization of Monoaromatic Hydrocarbons using Radiation Pulses of Ultrashort Duration: Monohalobenzenes and Azabenzenes

Using 50-fs, 800-nm pulses, we study the intense-field ionization and fragmentation of the monohalobenzenes C_(6)H_(5)-X (X=F, Cl, Br, I) and of the heterocyclics azabenzene C5H5N (pyridine) and the three diazabenzenes C_(4)H_(4)N_(2) (pyridazine, pyrimidine, and pyrazine). Avoiding focal intensity averaging we find indications of resonance-enhanced MPI. In the monohalobenzenes the propensity for fragmentation increases for increasing Z: fluorobenzene yields predominantly C6H5Fn+, while iodobenzene yields atomic ions with charges up to I^(8+). We ascribe this to the heavy-atom effect: the large charge of the heavy halogens' nuclei induces ultrafast intersystem crossing to dissociative triplet states

Increased Frequency of Moderate Intensity Walking Increases Consumption of Low Energy Density Foods

Panek-Scarborough, L., Temple, J., University at Buffalo, Buffalo, NY Figure 1: Mean + SEM change in laboratory energy consumed from pre to post exercise intervention from HED foods (top) and LED foods (bottom). The 5 day/week group consumed significantly more energy from LED food from pre- to post-exercise treatment (p = 0.002) compared to the other groups. Background: There is evidence that exercise has an effect on the type and amount of food consumed. One factor that regulates eating is the reinforcing value of food. While previous studies have demonstrated interactions between exercise and eating, to date, no one has investigated the influence of exercise frequency on the reinforcing value of food. Purpose: The purpose of this study was to test the hypothesis that varying frequencies of a short-term exercise regimen alters the reinforcing value of low energy density (LED) and high energy density (HED) foods in sedentary male and female adults. In addition, we predicted that increased frequency of physical activity would be associated with greater intake of LED foods and reduced intake of HED foods. Methods: Eighteen to 50 year old sedentary adults were randomized to 0, 1, 3, or 5 days/week of exercise. We measured the reinforcing value and intake of LED and HED foods at baseline and again after two weeks of exercise. Results: We found no effect of exercise frequency on the reinforcing value of HED or LED food over time (all p \u3e 0.05). However, exercise frequency effected the amount of energy consumed from LED food (p = 0.002) with the 5 days/week group consuming significantly more LED food after two weeks of exercise compared to the other groups. There was no significant effect of exercise frequency on energy intake from HED foods. Conclusion: This study suggests that increasing exercise frequency in sedentary adults may increase consumption of healthier food options, such as fruits and vegetables. Future studies will examine the impact of a longer exercise intervention and/or a higher intensity or interval type training on the reinforcing value of food and on LED and HED food intake

Solubility studies of ultra pure transition elements in ultra pure alkali metals

Solubility of pure iron, molybdenum, niobium, and tantalum in liquid potassiu

Book reviews

Teaching/Communication/Extension/Profession,

Steady and Stable: Numerical Investigations of Nonlinear Partial Differential Equations

Excerpt: Mathematics is a language which can describe patterns in everyday life as well as abstract concepts existing only in our minds. Patterns exist in data, functions, and sets constructed around a common theme, but the most tangible patterns are visual. Visual demonstrations can help undergraduate students connect to abstract concepts in advanced mathematical courses. The study of partial differential equations, in particular, benefits from numerical analysis and simulation

Z-2 Threaded Insert Design and Testing

NASA's Z-2 prototype space suit contains several components fabricated from an advanced hybrid composite laminate consisting of IM10 carbon fiber and fiber glass. One requirement was to have removable, replaceable helicoil inserts to which other suit components would be fastened. An approach utilizing bonded in inserts with helicoils inside of them was implemented. During initial assembly, cracking sounds were heard followed by the lifting of one of the blind inserts out of its hole when the screws were torqued. A failure investigation was initiated to understand the mechanism of the failure. Ultimately, it was determined that the pre-tension caused by torqueing the fasteners is a much larger force than induced from the pressure loads of the suit which was not considered in the insert design. Bolt tension is determined by dividing the torque on the screw by a k value multiplied by the thread diameter of the bolt. The k value is a factor that accounts for friction in the system. A common value used for k for a non-lubricated screw is 0.2. The k value can go down by as much as 0.1 if the screw is lubricated which means for the same torque, a much larger tension could be placed on the bolt and insert. This paper summarizes the failure investigation that was performed to identify the root cause of the suit failure and details how the insert design was modified to resist a higher pull out tension

Regge behaviour of distribution functions and t and x-evolutions of gluon distribution function at low-x

In this paper t and x-evolutions of gluon distribution function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi(DGLAP) evolution equation in leading order(LO) at low-x, assuming the Regge behaviour of quark and gluon at this limit, are presented. We compare our results of gluon distribution function with MRST 2001, MRST 2004 and GRV '98 parameterizations and show the compatibility of Regge behaviour of quark and gluon distribution functions with perturbative quantum chromodynamics(PQCD) at low-x. We also discuss the limitations of Taylor series expansion method used earlier to solve DGLAP evolution equations, in the Regge behaviour of distribution functions.Comment: 19 pages, 7 figure

Energy embodied in household cookery: the missing part of a sustainable food system? Part 1: A method to survey and calculate representative recipes

This paper firstly reviews the current state of knowledge on sustainable cookery and the environmental impacts of the food consumption phase. It then uses the example of a dish of roast beef and Yorkshire pudding to explore energy use in food production and consumption. Part 1 of this paper conducts a meta-analysis of 33 roast beef and Yorkshire pudding recipes in order to create a representative recipe for analysis. Part 2 of this paper then uses life cycle assessment and energy use data is coupled with the representative recipe of roast beef and Yorkshire pudding, to calculate the embodied energy of the meal. Seven interventions are modelled to illustrate how sustainable cookery can play a role as part of a sustainable food system. Interventions show that sustainable cookery has the potential to reduce cookery related energy use by 18%, and integrating sustainable cookery within a sustainable food system has the potential to reduce the total energy use by 55%. Finally, the paper discusses the issue of how the adoption of the sustainable cookery agenda may help or hinder attempts to shift consumers towards sustainable diets