Chemical abundances of late-type pre-main sequence stars in the σ\sigma-Orionis cluster

The young $\sigma$-Orionis cluster is an important location for understanding the formation and evolution of stars, brown dwarfs, and planetary-mass objects. Its metallicity, although being a fundamental parameter, has not been well determined yet. We present the first determination of the metallicity of nine young late-type stars in $\sigma$-Orionis. Using the optical and near-infrared broadband photometry available in the literature we derive the effective temperatures for these nine cluster stars, which lie in the interval 4300--6500 K (1--3 \Msuno). These parameters are employed to compute a grid of synthetic spectra based on the code MOOG and Kurucz model atmospheres. We employ a $\chi^2$-minimization procedure to derive the stellar surface gravity and atmospheric abundances of Al, Ca, Si, Fe, Ni and Li, using multi-object optical spectroscopy taken with WYFFOS+AF2 at at the William Herschel Telescope ($\lambda/\delta\lambda\sim7500$). The average metallicity of the $\sigma$-Orionis cluster is [Fe/H] $= -0.02\pm0.09\pm0.13$ (random and systematic errors). The abundances of the other elements, except lithium, seem to be consistent with solar values. Lithium abundances are in agreement with the "cosmic" $^7$Li abundance, except for two stars which show a $\log \epsilon(\mathrm{Li})$ in the range 3.6--3.7 (although almost consistent within the error bars). There are also other two stars with $\log \epsilon(\mathrm{Li})\sim 2.75$. We derived an average radial velocity of the $\sigma$-Orionis cluster of $28\pm4$km/s. The $\sigma$-Orionis metallicity is roughly solar.Comment: Accepted for publication in Astronomy and Astrophysic

Growth of Low-Density Vertical Quantum Dot Molecules with Control in Energy Emission

In this work, we present results on the formation of vertical molecule structures formed by two vertically aligned InAs quantum dots (QD) in which a deliberate control of energy emission is achieved. The emission energy of the first layer of QD forming the molecule can be tuned by the deposition of controlled amounts of InAs at a nanohole template formed by GaAs droplet epitaxy. The QD of the second layer are formed directly on top of the buried ones by a strain-driven process. In this way, either symmetric or asymmetric vertically coupled structures can be obtained. As a characteristic when using a droplet epitaxy patterning process, the density of quantum dot molecules finally obtained is low enough (2 × 108 cm−2) to permit their integration as active elements in advanced photonic devices where spectroscopic studies at the single nanostructure level are required

Academic self-efficacy in first year students college of health sciences

Self-efficacy learning is an important component of learning for college. Academic self-efficacy refers to the degree of confidence that health sciences students could successfully complete on college-task. The purpose of this research lies on the specific characteristics of health sciences students according to their academic self-efficacy by comparing their profiles with students that chose a different discipline. The Academic self-efficacy sample was done to 2089 subjects: 902 women and 1187 men, all of them freshmen students from the different careers at the Autonomous University of Chihuahua who responded to a survey questionnaire, with an average age of 18.23 years (SD = 0.74). This is a quantitative approach with a descriptive survey design type. The results obtained by comparing students of health sciences, with students from other disciplines show that perceived self-efficacy in academic behaviors is very similar each other

Definition of a FPGA-based SoC architecture for PRBS transmission in optical spectroscopy

Optical spectroscopy is a well-known tool typically employed for characterizing the properties of materials by analyzing their iteration with light. One of the most spread techniques is the dual comb spectroscopy, since it accomplishes ultra-high resolution, and high sensitivity measurements with a relatively simple platform including a single, relatively narrowband photodetector. The employed optical dual comb can be implemented through electro-optical (EO) modulation driven by pseudo-ransom binary sequences (PRBS) at high data rates, commonly in the range of tens of Gbps. For that purpose, the runtime generation and transmission of adaptive PRBS is still an open challenge, often involving expensive and not flexible high-speed digital systems, with a few commercially available solutions that sometimes do not match the application requirements efficiently. In this context, this work describes the definition and implementation of a System-on-Chip (SoC) architecture, based on a FPGA device, capable of generating and transmitting two PRBS for a dual comb, at a data rate up to 5 Gbps. The architecture can be configured and its operation modified in run time, thanks to the general-purpose processor involved, in charge of managing an Ethernet link to receive new PRBS to be transmitted or set up certain parameters. The proposed design has been validated experimentally on a dual comb spectroscopy measurement, where the absorption of a hydrogen cyanide (HCN) gas cell has been successfully characterized.Agencia Estatal de InvestigaciónMinisterio de Ciencia e Innovació

Perceived Body Image in Psychology Students from Yucatán, Mexico

Body image is an important psychological component related to current health issues such as eating disorders. It is also related to social, peer, and family pressure, by which men and women are affected to different degrees. Thus, the goal of the present research was to compare the perceived body image profiles in Mexican psychology students. The total sample consisted of 271 students; 139 women and 132 men from the Autonomous University of Yucatán, ages ranged between 17 and 28 years. The approach adopted in this research was quantitative with a descriptive survey like design. The results from the multivariate analyses of variance followed up by univariate analyses of variance, show that men report a better perceived body image than women on the factors behaviors oriented towards maintaining the physical shape (F = 317.008, p < .001) and care of physical aspect (F = 19.939, p < .001); and no significant differences on the factors of subjective importance of corporality and self-assessed physical attractiveness. These results show that in general men, in comparison to women show lower levels of dissatisfaction with their body image. Regardless, it is necessary that more research on the matter be developed given that the topic transcends the scope of the present research

Clues from Spitzer/IRS spectra on the Compton thickness and the existence of the dusty torus

[Context]: Most of the optically classified low-ionisation, narrow emission-line regions (LINERs) nuclei host an active galactic nucleus (AGN). However, how they fit into the unified model (UM) of AGN is still an open question. [Aims]: The aims of this work are to study at mid-infrared (mid-IR) (1) the Compton-thick nature of LINERs (i.e. hydrogen column densities of NH> 1.5 × 1024 cm-2) and (2) the disappearance of the dusty torus in LINERs predicted from theoretical arguments. [Methods]: We have compiled all the available low spectral-resolution, mid-IR spectra of LINERs from the InfraRed Spectrograph (IRS) onboard Spitzer. The sample contains 40 LINERs. We have complemented the LINER sample with Spitzer/IRS spectra of PGQSOs, Type-1 Seyferts (S1s), Type-2 Seyferts (S2s), and StarBurst (SB) nuclei. We studied the AGN compared to the starburst content in our sample using different indicators: the equivalent width of the polycyclic aromatic hydrocarbon at 6.2 μm, the strength of the silicate feature at 9.7 μm, and the steepness of the mid-IR spectra. We classified the spectra as SB-dominated and AGN-dominated, according to these diagnostics and compared the average mid-IR spectra of the various classes. Moreover, we studied the correlation between the 12 μm luminosity, νLν(12 μm), and the 2−10 keV energy band X-ray luminosity, LX(2−10 keV). [Results]: In 25 out of the 40 LINERs (i.e. 62.5%), the mid-IR spectra are not SB-dominated, similar to the comparison S2 sample (67.7%). The average spectra of both SB-dominated LINERs and S2s are very similar to the average spectrum of the SB class. The average spectrum of AGN-dominated LINERs is different from the average spectra of the other optical classes, showing a rather flat spectrum at 6-28 μm. We find that the average spectrum of AGN-dominated LINERs with X-ray luminosities LX(2−10 keV) > 1041 erg/s is similar to the average mid-IR spectrum of AGN-dominated S2s. However, faint LINERs (i.e. LX(2−10 keV) < 1041 erg/s) show flat spectra different from any of the other optical classes. The correlation between νLν(12 μm) and LX(2−10 keV) for AGN nicely extends towards low luminosities only if SB-dominated LINERs are excluded and if the 2−10 keV band X-ray luminosity is corrected in Compton-thick LINER candidates. [Conclusions]: We find that LINERs proposed as Compton-thick candidates at X-ray wavelengths may be confirmed according to the X-ray to mid-IR luminosity relation. We show evidence that the dusty-torus disappear when their bolometric luminosity is below Lbol ≃ 1042 erg/s. We suggest that the dominant emission at mid-IR of faint LINERs might be a combination of an elliptical galaxy host (characterised by the lack of gas), a starburst, a jet, and/or ADAF emission. Alternatively, the mid-IR emission of some of these faint LINERs could be a combination of elliptical galaxy plus carbon-rich planetary nebulae. To reconcile the Compton-thick nature of a large number of LINERs without dusty-torus signatures, we suggest that the material producing the Compton-thick X-ray obscuration is free of dust.This research has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under the grant (project refs. AYA2013-42227-P, AYA 2012-39168-C03-01, and AYA 2010-15169) and by La Junta de Andalucia (TIC 114). AAH acknowledges support from grant AYA2012-31447. D.D. acknowledges support from grant 107313 from PAPIIT, UNAM. C.R.A. is supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme (PIEF-GA-2012-327934).Peer Reviewe

Incidence of cardiovascular events and associated risk factors in kidney transplant patients: a competing risks survival analysis

[Abstract] Background: The high prevalence of cardiovascular risk factors among the renal transplant population accounts for increased mortality. The aim of this study is to determine the incidence of cardiovascular events and factors associated with cardiovascular events in these patients. Methods: An observational ambispective follow-up study of renal transplant recipients (n = 2029) in the health district of A Coruña (Spain) during the period 1981-2011 was completed. Competing risk survival analysis methods were applied to estimate the cumulative incidence of developing cardiovascular events over time and to identify which characteristics were associated with the risk of these events. Post-transplant cardiovascular events are defined as the presence of myocardial infarction, invasive coronary artery therapy, cerebral vascular events, new-onset angina, congestive heart failure, rhythm disturbances, peripheral vascular disease and cardiovascular disease and death. The cause of death was identified through the medical history and death certificate using ICD9 (390-459, except: 427.5, 435, 446, 459.0). Results: The mean age of patients at the time of transplantation was 47.0 ± 14.2 years; 62% were male. 16.5% had suffered some cardiovascular disease prior to transplantation and 9.7% had suffered a cardiovascular event. The mean follow-up period for the patients with cardiovascular event was 3.5 ± 4.3 years. Applying competing risk methodology, it was observed that the accumulated incidence of the event was 5.0% one year after transplantation, 8.1% after five years, and 11.9% after ten years. After applying multivariate models, the variables with an independent effect for predicting cardiovascular events are: male sex, age of recipient, previous cardiovascular disorders, pre-transplant smoking and post-transplant diabetes. Conclusions: This study makes it possible to determine in kidney transplant patients, taking into account competitive events, the incidence of post-transplant cardiovascular events and the risk factors of these events. Modifiable risk factors are identified, owing to which, changes in said factors would have a bearing of the incidence of events

A randomized clinical trial to determine the effectiveness of CO-oximetry and anti-smoking brief advice in a cohort of kidney transplant patients who smoke: study protocol for a randomized controlled trial

Randomized controlled trial[Abstract]Background: The cardiovascular risk in renal transplant patients is increased in patients who continue to smoke after transplantation. The aim of the study is to measure the effectiveness of exhaled carbon monoxide (CO) measurement plus brief advisory sessions, in comparison to brief advice, to reduce smoking exposure and smoking behavior in kidney transplant recipients who smoke. The effectiveness will be measured by: (1) abandonment of smoking, (2) increase in motivation to stop smoking, and (3) reduction in the number of cigarettes smoked per day. Design: a randomized, controlled, open clinical trial with blinded evaluation. Scope: A Coruña Hospital (Spain), reference to renal transplantation in the period 2012-2015. Inclusion criteria: renal transplant patients who smoke in the precontemplation, contemplation or preparation stages according to the Prochaska and DiClemente's Stages of Change model, and who give their consent to participate. Exclusion criteria: smokers attempting to stop smoking, patients with terminal illness or mental disability that prevents them from participating. Randomization: patients will be randomized to the control group (brief advisory session) or the intervention group (brief advisory session plus measuring exhaled CO). The sample target size is n = 112, with 56 patients in each group. Allowing for up to 10 % loss to follow-up, this would provide 80 % power to detect a 13 % difference in attempting to give up smoking outcomes at a two-tailed significance level of 5 %. Measurements: sociodemographic characteristics, cardiovascular risk factors, treatment, rejection episodes, infections, self-reported smoking habit, drug use, level of dependence (the Fagerström test), stage of change (Prochaska and DiClemente's Stages of Change model), and motivation to giving up smoking (the Richmond test). Response: the effectiveness will be evaluated every 3, 6, 9 and 12 months as: pattern of tobacco use (self-reported tobacco use), smoking cessation rates, carbon monoxide (CO) levels in exhaled air measured by CO-oximetry, urinary cotinine tests, nicotine dependence (Fagerström test), motivational stages of change (Prochaska and DiClemente's stages) and motivation to stop smoking (the Richmond test). Analysis: descriptive statistics and linear/logistic multiple regression models will be performed. Clinical relevance will be measured as relative risk reduction, absolute risk reduction and the number needed to treat. Ethics: informed consent of the patients and Ethical Review Board was obtained (code 2011/061). Discussion: Tobacco is a modifiable risk factor that increase the risk of morbidity and mortality in kidney transplant recipients. If effectiveness of CO-oximetry is confirmed to reduce tobacco exposure, we would have an intervention that is easy to use, low cost and with great implications about cardiovascular risk prevention in these patients.Instituto de Salud Carlos III; PI11/0135

Stevensite-based geofilter for the retention of tetracycline from water

The antibiotic tetracycline, is considered a contaminant of emerging concern due to its presence in wastewater effluents, surface waters and groundwaters. Adsorption of tetracycline on soils and clays has been extensively studied to remove the contaminant from the water. A decreasing adsorption as the pH increases is normally reported in the pH range 3–9. However, adsorption isotherms performed on a commercial stevensite presented increasing adsorption with the increasing pH, in the pH range 2–8. This is very interesting since the pH in natural and wasterwaters are normally in the range 6–8. A laboratory design of a geofilter using a mixture of sand and stevensite was tested against an inflow solution of tetracycline 1 g/L, NaNO3 0.1 M and pH = 7 in an advective transport cell experiment. The number of tetracycline molecules exceed by >3 times the number exchangeable positions in the stevensite geofilter. Under these conditions, the TC adsorption on the geofilter reaches 590 mg/g, surpassing the retention capacity of most adsorbents found in literature. Besides, the tetracycline is completely desorbed by the inflow of a saline solution (Mg(NO3)2 0.5 M, at pH = 2) with capacity to replace the exchangeable positions, thus, recovering the geofilter and the tetracyclineThis work has been financially supported by the Spanish Ministry of Economy and Competitiveness through the AGL2016-78490-R projec