Laser Shock Microformingof Thin Metal Sheets with ns Lasers

Continuous and long-pulse lasers have been used for the forming of metal sheets in macroscopic mechanical applications. However, for the manufacturing of micro-electromechanical systems (MEMS), the use of ns laser pulses provides a suitable parameter matching over an important range of sheet components that, preserving the short interaction time scale required for the predominantly mechanical (shock) induction of deformation residual stresses, allows for the successful processing of components in a medium range of miniaturization without appreciable thermal deformation.. In the present paper, the physics of laser shock microforming and the influence of the different experimental parameters on the net bending angle are presented

Laser Shock Microforming of Thin Metal Sheets

Continuous and long-pulse lasers have been used for the forming of metal sheets in macroscopic mechanical applications. However, for the manufacturing of micro-electromechanical systems (MEMS), the applicability of such type of lasers is limited by the long-relaxation-time of the thermal fields responsible for the forming phenomena. As a consequence of such slow relaxation, the final sheet deformation state is attained only after a certain time, what makes the generated internal residual stress fields more dependent on ambient conditions and might make difficult the subsequent assembly process from the point of view of residual stresses due to adjustment. The use of ns laser pulses provides a suitable parameter matching for the laser forming of an important range of sheet components used in MEMS that, preserving the short interaction time scale required for the predominantly mechanic (shock) induction of deformation residual stresses, allows for the successful processing of components in a medium range of miniaturization, particularly important according to its frequent use in such systems. In the present paper, a discussion is presented on the physics of laser shock microforming and the influence of the different effects on the net bending angle. The experimental setup used for the experiments, sample fabrication and experimental results of influence of number of laser pulses on the net bending angle are also presented

The Use Of Peer Tutoring To Improve The Passing Rates In Mathematics Placement Exams Of Engineering Students: A Success Story

This paper describes a highly successful peer tutoring program that has resulted in an improvement in the passing rates of mathematics placement exams from 16% to 42%, on average. Statistical analyses were conducted using a Chi-Squared (X2) test for independence and the results were statistically significant (p-value much less than 0.05). These encouraging results suggest that this type of initiative should be institutionalized at the end of the grant period that funds it. The paper describes the structure of the program, the conditions of the university in which it is being implemented, the details of the statistical analyses, and its impact in engineering education. This model may easily be replicated in academic institutions with similar conditions.

Emotional intelligence as a predictor of job satisfaction: the mediating role of conflict management in nurses

BackgroundEmotional Intelligence (EI) has emerged as a pivotal factor in work effectiveness and well-being within the healthcare domain. Specifically, its significance is heightened in the nursing sector, where emotional and social demands are high. Additionally, job satisfaction and conflict management are recognized as vital predictors of patient care service quality. However, there is a dearth of research addressing the mediating role of conflict management in the relationship between EI and job satisfaction within a nursing context.ObjectiveThis study aims to assess the mediating role of conflict management in the relationship between emotional intelligence and job satisfaction among nurses.MethodsThe STROBE checklist for cross-sectional studies was followed. A cross-sectional and explanatory design was employed. Data were collected using self-reported questionnaires to measure emotional intelligence, conflict management, and job satisfaction. Structural Equation Modeling (SEM) was conducted to test the proposed hypotheses.ResultsA total of 208 nurses aged between 18 and 65 years participated (M = 41.18, SD = 8.942). The findings confirmed a positive relationship between emotional intelligence and conflict management (β = 0.64, p < 0.001). Similarly, a positive relationship between conflict management and job satisfaction was observed (β = 0.37, p < 0.001). Moreover, conflict management was validated as a mediator in the relationship between emotional intelligence and job satisfaction (β = 0.77, p = 0.002).ConclusionThe study underscores the importance of emotional intelligence and conflict management as predictors of job satisfaction in nurses. The results suggest that interventions aimed at enhancing emotional intelligence might be an effective avenue for increasing job satisfaction, especially when conflict management strategies are integrated

Depression, professional self-efficacy, and job performance as predictors of life satisfaction: the mediating role of work engagement in nurses

BackgroundThe life satisfaction and job performance of nursing professionals are affected by a multitude of factors, including work engagement, self-efficacy, and depression. The Job Demands-Resources (JD-R) model provides a theoretical framework to explore these relationships.ObjectiveOur study aimed to analyze the primary goal of this research, which is to examine the mediating role of work engagement in the relationship between depression, professional self-efficacy, job performance, and their impact on life satisfaction in nurses, using the JD-R theory as a guide.MethodsThis cross-sectional study involved 579 participants aged between 21 to 57 years (M = 39, SD = 9.95). Mediation analysis was used to examine the influence of depression, self-efficacy, and job performance on work engagement, and in turn, its effect on life satisfaction.ResultsFindings indicated that work engagement plays a crucial mediating role between depression, self-efficacy, job performance, and life satisfaction. Interventions to increase work engagement could assist nurses in better managing depression and improving their performance and life satisfaction.ConclusionsOur study highlights the need for workplace policies and strategies that foster work engagement and self-efficacy among nurses while effectively managing job demands to prevent depression. Moreover, these findings underscore the importance of the JD-R theory to understand and improve nurses' job satisfaction and performance, and suggest areas for future research, including exploring other potential factors and applying these findings across different contexts and cultures

Evaluación del comportamiento a la fatiga de másticos bituminosos reforzados con poliolefinas a través de una metodología basada en energía disipada

Polymers are known to improve the fatigue resistance of sphalt mastics. However, undesirable results can be obtained if the polymer is not successfully integrated into the bitumen binder. The goal of this work is to evaluate the effect of the addition of three selected polyolefins on their mastic’s fatigue performance. Low and high density polyethylenes (LDPE and HDPE) and polypropylene (PP) were chosen and used at the concentration of 4 wt.%. A dissipated energy approach was used in order to analyze the fatigue resistance, at 25 ºC, of the three composites studied. Dynamic time sweeps at and above the linear viscoelastic threshold were carried out. Based on that, the results demonstrated a better improvement when the LDPE was considered. For that binder, fluorescence optical microscopy observations at 25 ºC provided morphological evidence of a more homogeneous bitumen-polymer distribution which could be behind the improved fatigue behavior.El uso de polímeros mejora la resistencia a la fatiga de los másticos asfálticos. Sin embargo, se pueden obtener resultados no esperados si el polímero no se integra eficientemente en el ligante bituminoso. El objetivo de este trabajo es evaluar el efecto de la adición de 3 poliolefinas sobre el comportamiento a la fatiga. Se seleccionaron polietilenos de baja y alta densidad (PEBD y PEAD) y polipropileno (PP) que se usaron al 4 % en peso. Se empleó una metodología basada en la energía disipada, a 25 ºC. Se realizaron ensayos dinámicos de barrido de tiempo en el límite y por encima del intervalo de viscoelasticidad lineal, que demostraron un mejor comportamiento para el mástico que contenía PEBD. Para él, se observó a través de microscopía óptica de fluorescencia que la distribución de polímero en el betún era mucho más homogénea, y éste podría ser el motivo del comportamiento mejorado

Statins and protein prenylation in cancer cell biology and therapy

El pdf del artículo es la versión post-print.The use of statins has scaled up to become one of the most prescribed medicines in the world and have been very useful in the manegement of cardiovascular diseases and related mortality. The disclosure of their chemical structure similar to that of hydroxy methyl glutaryl-CoA (HMG-CoA) revealed their ability to compete with and inhibit the rate-limiting enzyme HMG-CoA reductase that catalyzes the synthesis of mevalonate, which then serves as the precursor for isoprenoids and cholesterol in the mevalonate pathway. While most of the effects of statins are associated with the lowering of cellular cholesterol levels, it is clear that they also blunt the non-sterol branch of the mevalonate pathway, decreasing formation of isoprenoids and altering protein-prenylation, a critical event in the posttranslational modulation of proteins involved in the regulation of cell cycle progression, proliferation and signaling pathways. Randomized controlled trials for the prevention of cardiovascular diseases indicated that statins elicited provocative and unexpected benefits for reducing a number of different types of cancers, including colorectal carcinoma, melanoma, prostate and hepatocellular carcinoma, although in other cancer types the preclinical expectations of statins were dissapointing. In this review, we will describe the evidence and mechanisms underlying the potential beneficial use of statins and the role of protein prenylation in cancer prevention. Of relevance, the combination of statins with other anti cancer drugs may be a significant asset in malignancies resistant to current therapy. © 2012 Bentham Science Publishers.The work was supported by CIBEREHD, Fundación Mutua Madrileña, Fundació la Marató de TV3, PI11/03025 (META) and grants PI09/0056 (Instituto de Salud Carlos III), SAF2009-11417, SAF2008-02199, SAF2011-23031 (Plan Nacional de I+D), Spain; and P50-AA-11999 (Research Center for Liver and Pancreatic Diseases, NIAAA/NIH).Peer Reviewe

Impact of myxomatosis on densities of Iberian hares (Lepus granatensis) in North-western Spain: implications for management and sustainable hunting

[ENG]Outbreaks of myxomatosis in Iberian hares (Lepus granatensis) were detected for the first time in Spain in 2018. The disease spread to a significant proportion of the species range, negatively affecting the hare populations. In this study, we analyzed the impact of myxomatosis at hunting grounds of Castilla y León (Northern Spain), comparing hare density during two consecutive hunting seasons; the first when outbreaks were detected for the first time (season 1, Oct 2019-Jan 20) and the second after the spread of the disease (season 2, Oct 2020-Jan 21). Data was gathered from 1,102 hunts from 178 hunting grounds through “coursing”, a hunting type in which hunters and greyhounds search for hares, allowing the estimation of hare density. Overall, hare density decreased significantly, from 12.7 hare/100 ha in season 1 to 4.7 hare/100 ha in season 2. The percentage of hares suspected to be affected by myxomatosis (sick and dead) per hunt was higher in season 1 (14.4%) compared to season 2 (10.7%). For both seasons, this proportion was higher when hunting season was started (20.7%, October), compared to the remaining months (4.7%, November–January). However, the proportion of hunting grounds affected increased from 44% in season 1 to 66.7% in season 2. Our research confirmed a 62.7% reduction in hare density in Castilla y León after the spread of myxomatosis and identified scenarios of possible depletion when densities were below 4–5 hare/100 ha. As myxomatosis becoming endemic in Iberian hares is likely, hunters and game managers should continue current monitoring and disease surveillance and make management decisions accordingly.SIJunta de Castilla y LeónFundación Artemisa

Development and validation of a scale for streaming dependence (SDS) of online games in a Peruvian population

BackgroundAddiction to online video game streaming has become one of the most appealing ways to occupy leisure time and is one of the most popular activities. The satisfaction it provides and the time invested in it are two of the main reasons why it is preferred. However, despite the clear benefits that this activity offers, in some cases, excessive use can lead to personal and/or family problems or abuse.ObjectiveThe objective of the study was to develop and validate a scale to measure potential traits of dependence on online game streaming. The participants were 423 Peruvian adults aged between 18 and 47 years (M = 22.87, SD = 5.02). The Streaming Dependence Scale (SDS) was developed based on a literature review, and exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were conducted.ResultsThe scale showed adequate internal consistency (α, CR, ω, and H > 80). Confirmatory analysis confirmed the one-dimensional structure (χ2 = 10.250, df = 5; p = 0.068; CFI = 0.98, TLI = 0.96, RMSEA = 0.06, SRMR = 0.05).ConclusionThe brief SDS is a valid and reliable measure that can be used as a useful tool to identify and evaluate streaming dependence