A comparative analysis of two methods for the calculation of electric-field-induced perturbations to molecular vibration

Two common methods of accounting for electric-field-induced perturbations to molecular vibration are analyzed and compared. The first method is based on a perturbation-theoretic treatment and the second on a finite-field treatment. The relationship between the two, which is not immediately apparent, is made by developing an algebraic formalism for the latter. Some of the higher-order terms in this development are documented here for the first time. As well as considering vibrational dipole polarizabilities and hyperpolarizabilities, we also make mention of the vibrational Stark effec

A quantum molecular similarity analysis of changes in molecular electron density caused by basis set flotation and electric field application

Quantum molecular similarity (QMS) techniques are used to assess the response of the electron density of various small molecules to application of a static, uniform electric field. Likewise, QMS is used to analyze the changes in electron density generated by the process of floating a basis set. The results obtained show an interrelation between the floating process, the optimum geometry, and the presence of an external field. Cases involving the Le Chatelier principle are discussed, and an insight on the changes of bond critical point properties, self-similarity values and density differences is performed

Temporal variability and trends of the downward solar radiation over Europe during the 20th century, with regional focus in the dimming/brightening phenomena on the Iberian Peninsula

Proyecto de investigación elaborado a partir de una estancia en el Institute for Atmospheric and Climate Science, a Alemanya, entre 2010 y 2012. La radiación solar que alcanza la superficie terrestre es un factor clave entre los procesos que controlan el clima de la Tierra, dado el papel que desempeñan en el balance energético y el ciclo hidrológico. Establecer su contribución al cambio climático reciente supone una gran dificultad debido a la complejidad de los procesos implicados, la gran cantidad de información requerida, y la incertidumbre de las bases de datos disponibles en la actualidad. Así, el objetivo principal del proyecto ha consistido en generar una base de datos de insolación incluyendo las series más largas (desde finales del siglo XIX) disponibles en toda Europa. Esta base de datos complementa para nuestro continente el Global Energy Balance Archive (GEBA) que mantiene y gestiona el grupo que ha acogido al receptor de la ayuda postdoctoral, y permite extender espacial (especialmente en países del sur de Europa) y temporalmente las series climáticas disponibles de mediciones de irradiancia solar. Como la insolación es un proxy de la irradiancia solar, el proyecto actual también ha tratado de calibrar de forma exhaustiva ambas variables, a fin de generar una nueva base de datos reconstruida de esta segunda variable que esté disponible desde finales del siglo XIX en Europa. Un segundo objetivo del proyecto ha consistido en continuar trabajando a escala de mayor detalle sobre la Península Ibérica, con el fin de proporcionar una mejor comprensión del fenómeno del “global dimming/brightening” y su impacto en el ciclo hidrológico y balance energético. Finalmente, un tercer objetivo del presente proyecto postdoctoral ha consistido en continuar estudiando los posibles ciclos semanales a gran escala de diferentes variables climáticas, línea de investigación de interés para la detección de posibles efectos de los aerosoles antrópicos en el clima a escalas temporales breves, y consecuentemente estrechamente vinculado al fenómeno del “global dimming/brightening”.

The effects of walking while working on productivity and health: a field experiment

Lack of physical activity can cause health problems and diminish organizational productivity. We conducted a 12-months long field experiment in a financial services company to study the effects of slow-moving treadmills outfitted for office work on employee productivity and health. 43 sedentary volunteers were assigned randomly to two groups to receive treadmill workstations 7 months apart. Employees could opt at will for standard chair-desk arrangement. Biometric measurements were taken quarterly and weekly online performance surveys were administered to study participants and to more than 200 non-participants and their supervisors.In this study we explore three questions concerning the effects of the introduction of treadmills in the workplace. (1) Does it improve overall physical activity? (2) Does it improve health measures? (3) Does it improve performance? The answers are as follows. (1) Yes (net effect of almost half an hour a day). (2) Yes (small gains, one minor decline). (3) No and yes (initial decline followed by increase to recover to initial level within one year) – based on weekly employee self reports.