Dielectric susceptibility of the Coulomb-glass

We derive a microscopic expression for the dielectric susceptibility X of a Coulomb glass, which corresponds to the definition used in classical electrodynamics, the derivative of the polarization with respect to the electric field. The fluctuation–dissipation theorem tells us that is a function of the thermal fluctuations of the dipole moment of the system. We calculate X numerically for three–dimensional Coulomb glasses as a function of temperature and frequency.We acknowledge financial support from the DGES project number PB96-1118, SMWK, and DFG (SFB 393). A great part of this work was performed during A. D.-S.’s visit at the IFW Dresden; A. D.-S. thanks the IFW for its hospitality

The use of natural products for sleep: A common practice?

Despite a paucity of data on efficacy and safety of natural (herbal and dietary) products, their use appears to be widespread. This study aimed at examining the frequency of natural products’ use for sleep and their correlates in a population-based sample. Methods A randomly selected sample of adults (n = 997; 59.9% women) from the province of Quebec completed a postal survey on sleep, use of sleep-promoting products (natural products, prescribed medication, over-the-counter medication and alcohol), physical and mental health, lifestyle habits and demographics. Results A total of 18.5% of participants reported having used natural products as sleep aids in the past 12 months, with chamomile being the most popular product. Participants who exclusively used natural products as sleep aids (10.3% of the sample) were predominantly females, younger and had a higher educational level than those using prescribed medications. Natural products users reported engaging in more health-promoting behaviors than the nonusers of sleep aids and, despite the presence of subthreshold insomnia symptoms (mean Insomnia Severity Index score = 9.33), they tended to perceive themselves as healthier when compared with prescribed medication users and nonusers of sleep aids. Conclusions The use of natural products as sleep aids is a common practice. Often associated with a general health-promoting lifestyle, it may reflect the common perception that natural products are necessarily beneficial for sleep and without risk

High-throughput wide dynamic range procedure for the simultaneous quantification of nicotine and cotinine in multiple biological matrices using hydrophilic interaction liquid chromatography-tandem mass spectrometry

A straightforward, high-throughput method was developed and fully validated for the simultaneous determination of the specific tobacco biomarkers nicotine and its main metabolite cotinine in a wide dynamic range and supporting the most common human biological matrices (urine, oral fluid and hair). Sample preparation was performed inside the very HPLC injection vials by pipetting 0.5 mL of the liquid samples, deuterated internal standards in alkaline solution and dichloromethane as extraction solvent. Solid samples (i.e. around 10 mg hair) were first submitted to alkaline digestion in the HPLC vials and processed accordingly. The organic phase (reached through the upper aqueous layer) was directly injected without further treatment. Instrumental analysis was performed using hydrophilic interaction (HILIC) ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Total chromatographic time was 2 min. The method covers a wide dynamic range making it fit-for-purpose for the analysis of samples covering entire populations, irrespective of the level of exposure or tobacco use. Calibration curves (r 2 > 0.995) covered the range 1-2000 ng/mL (or 0.05-100 ng/mg hair) for nicotine and 0.1-2000 ng/mL (or 0.005-100 ng/mg hair) for cotinine. Within-run and between-run precision and accuracy were typically below 10 %, and always below 20 % at the lower limit of quantification. The method was successfully applied to the analysis of samples from different projects involving multiple matrices

¿Cuál es la actitud de los médicos hacia el actual modelo de atención primaria?

ObjetivoDeterminar cómo es la actitud de los médicos hacia el actual modelo de atención primaria de salud y estimar su relación con variables de tipo sociodemográfico y/o laboral.DiseñoEstudio multicéntrico, transversal.EmplazamientoCentros de salud del Área II de la Región de Murcia.ParticipantesTotalidad de médicos generales, de familia y pediatras de los centros de salud mencionados (54 en total).Mediciones principalesComo instrumento de evaluación se utiliza la «Escala de actitudes hacia los contenidos de atención primaria de salud», de Ballesteros et al. Esta escala proporciona una puntuación total, así como una puntuación específica para cada una de las 7 dimensiones que la componen.ResultadosEn general, la actitud de los médicos es favorable (4,1 puntos de media sobre 5). En la dimensión «Inclusión de los profesionales del segundo nivel en atención primaria» es donde hemos encontrado una actitud menos favorable, siendo los médicos de familia los que se muestran más de acuerdo. En cuanto a las demás variables asociadas, los profesionales que trabajan en centros periféricos y en situación de interinidad muestran una actitud más positiva hacia el actual modelo.ConclusionesEl conocimiento de las actitudes de los profesionales, así como de las variables relacionadas, puede servir de base para diseñar posibles estrategias de intervención dirigidas a la mejora de la calidad asistencial en atención primaria y para una evolución positiva de los profesionales que prestan sus servicios.ObjectivesTo determine the attitude of doctors towards the current model of primary care and to calculate its relationship with social and demographic and/or work variables.DesignMulti-centre cross-sectional study.SettingHealth centres in Area II of the Murcia region.ParticipantsAll general practitioners, family doctors and paediatricians in the health centres mentioned (54 in all).Main measurementsThe «Scale of attitudes towards the contents of primary health care» by Ballesteros et al. was used as the tool of evaluation. This scale provides both a total score and a specific score for each of its 7 dimensions.ResultsIn general, doctors´ attitudes were favourable (4.1 points average out of 5). We found a less favourable attitude in the dimension «Inclusion of second-level professionals in primary care», with family doctors most in agreement. The professionals working in centres on the periphery and those without tenure had a more positive attitude towards the current model, for the remaining variables.ConclusionsUnderstanding professionals´ attitudes and the variables related to them may serve as a basis for designing intervention strategies aimed at improving the quality of primary care and for the positive evolution of professionals working in PC

Physiological mechanisms involved in the recovery of euonymus and laurustinus subjected to saline waters

The scarcity of water has frequently led to saline water being reused for the irrigation of ornamental shrubs. However, before the use of such waters can be expanded, the salt tolerance and other characteristics of the ornamentals involved, need to be considered along with their capacity to recover after salinity exposure. For this reason, Euonymus japonica (euonymus) and Viburnum tinus (laurustinus) plants were submitted for twenty weeks to three irrigation treatments applied at 100% water holding capacity: Control (EC<0.9dSm-1); NaCl solution, NaCl (EC: 4dSm-1); and wastewater, WW (EC: 4dSm-1). This was followed by a recovery period of eight weeks, when all the plants were watered in the control irrigation conditions. The results showed that biomass, leaf number and total leaf area of plants subjected to the saline treatments were lower than in the control at the end of both periods in both species. However, after recovery, only euonymus showed lower growth parameters than those observed in the saline period. The highest Na+ and Cl- concentrations were observed in saline plants at the end of saline period for both species, and were higher in shoots than in roots. The opposite was observed for the K+/Na+ and the Ca2+/Na+ ratios. In Laurustinus, the Ψstem did not diminish in the wastewater-irrigated plants with respect to the control, maintaining osmotic adjustment and a high Ψt, even after recovery, whereas in euonymus this did not occur at the end of recovery period. In both species the Pn and gs were similarly reduced during the saline exposure period. However, the recovery of gas exchange in laurustinus irrigated with wastewater might be closely related to the better water status of these plants. Although the aesthetic value and growth decreased in the plants of both species, the chemical properties of the waters applied had different effects in each case, especially as regards the capacity to recover from salinity. These results underline the importance to studying the physiological mechanisms involved in the recovery of plants. © 2013 Elsevier B.V.This work was supported by the projects: CICYT (AGL 2008-05258-CO2-1-2-AGR and AGL 2011-30022-CO2-01-02) and Fundación Séneca (15356/PI/10).Peer Reviewe

ESTUDIO DEL CRECIMIENTO DE HIPOCOTILOS ETIOLADOS DE ALTRAMUZ: ALARGAMIENTO DEL ÓRCANO Y VARIACIÓN DE TAMANO CELULAR

The growth of the etiolated hypocotyls of lupine has been studied. The distrihution of both the relative growth and the cellular paraineters shows that the length of the cell parallels with the elongation of the organ, and varies along this.Se estudia la distribuci6n y variación con la edad del crecimiento de hipocotilos etiolados de altramuz (Lupinus albus), determinando la velocidad de alargamiento del 6rgano y el valor de diferentes parámetros celulares. El tamaño celular evoluciona de forma paralela al alargamiento del hipocotilo y vana a lo largo del mismo

Dielectric susceptibility of the Coulomb-glass

We derive a microscopic expression for the dielectric susceptibility $\chi$ of a Coulomb glass, which corresponds to the definition used in classical electrodynamics, the derivative of the polarization with respect to the electric field. The fluctuation-dissipation theorem tells us that $\chi$ is a function of the thermal fluctuations of the dipole moment of the system. We calculate $\chi$ numerically for three-dimensional Coulomb glasses as a function of temperature and frequency

Non-ergodic effects in the Coulomb glass: specific heat

We present a numerical method for the investigation of non-ergodic effects in the Coulomb glass. For that, an almost complete set of low-energy many-particle states is obtained by a new algorithm. The dynamics of the sample is mapped to the graph formed by the relevant transitions between these states, that means by transitions with rates larger than the inverse of the duration of the measurement. The formation of isolated clusters in the graph indicates non-ergodicity. We analyze the connectivity of this graph in dependence on temperature, duration of measurement, degree of disorder, and dimensionality, studying how non-ergodicity is reflected in the specific heat.Comment: Submited Phys. Rev.

Formación y extracción de compuestos entre fosfowolframto y colorantes tiazinicos. Determinación espectrofotométrica de fosfatos

Phosphate anions don't form with basic dyestuffs extractable compounds. However the tungsto-phosphate associated to several dyestuffs are extracted with organic solvents. Between 0,2-10 p p m of orthophosphate is determined v&iacute;a formation of the ion-association complex of tungsto-phosphate with the thiazinic dyestuff Azur B. The azur Btungsto- phosphate is extracted into benzene-cyclohexanone 1/1 v/v and the absorbance in this solvent measured a 645 nm. Optimal conditions for the determination have been established, and the effects of foreign ions have been examined. The determination is highly selective. The stoichiometry and structure of the ion-association complex has been studied.Los aniones fosfato no forman con colorantes b&aacute;sicos compuestos extra&iacute;bles. Sin embargo, los fosfowolframatos asociados a ciertos colorantes son extra&iacute;bles por disolventes org&aacute;nicos. Se determina entre 0,2-10 p p m de fosfato por formaci&oacute;n del complejo de asociaci&oacute;n i&oacute;nica fosfowolframato con el colorante tiaz&iacute;nico Azur B. El fosfowolframatoazur B se extrae en benceno/ciclohexanona 1/1 v/v y se mide su absorbancia a 645 nm. Se establecen las condiciones &oacute;ptimas para la determinaci&oacute;n y se examina el efecto, de iones extra&ntilde;os. La determinaci&oacute;n es altamente selectiva. Se estudia la estequiometr&iacute;a y estructura del complejo de asociaci&oacute;n i&oacute;nica