Local Heat Dissipation and Elasticity of Suspended Silicon Nanowires Revealed by Dual Scanning Electron and Thermal Microscopies.

A novel combined setup, with a scanning thermal microscope (SThM) embedded in a scanning electron microscope (SEM), is used to characterize a suspended silicon rough nanowire (NW), which is epitaxially clamped at both sides and therefore monolithically integrated in a microfabricated device. The rough nature of the NW surface, which prohibits vacuum-SThM due to loose contact for heat dissipation, is circumvented by decorating the NW with periodic platinum dots. Reproducible approaches over these dots, enabled by the live feedback image provided by the SEM, yield a strong improvement in thermal contact resistance and a higher accuracy in its estimation. The results-thermal resistance at the tip-sample contact of 188±3.7K µW-1 and thermal conductivity of the NW of 13.7±1.6W m-1 K-1-are obtained by performing a series of approach curves on the dots. Noteworthy, the technique allows measuring elastic properties at the same time-the moment of inertia of the NW is found to be (6.1±1.0) × 10-30m4-which permits to correlate the respective effects of the rough shell on heat dissipation and on the NW stiffness. The work highlights the capabilities of the dual SThM/SEM instrument, in particular the interest of systematic approach curves with well-positioned and monitored tip motion.

Superior Thermoelectric Performance of SiGe Nanowires Epitaxially Integrated into Thermal Micro-Harvesters.

Semiconductor nanowires have demonstrated fascinating properties with applications in a wide range of fields, including energy and information technologies. Particularly, increasing attention has focused on SiGe nanowires for applications in a thermoelectric generation. In this work, a bottom-up vapour-liquid-solid chemical vapour Deposition methodology is employed to integrate heavily boron-doped SiGe nanowires on thermoelectric generators. Thermoelectrical properties -, i.e., electrical and thermal conductivities and Seebeck coefficient - of grown nanowires are fully characterized at temperatures ranging from 300 to 600 K, allowing the complete determination of the Figure-of-merit, zT, with obtained values of 0.4 at 600 K for optimally doped nanowires. A correlation between doping level, thermoelectric performance, and elemental distribution is established employing advanced elemental mapping (synchrotron-based nano-X-ray fluorescence). Moreover, the operation of p-doped SiGe NWs integrated into silicon micromachined thermoelectrical generators is shown over standalone and series- and parallel-connected arrays. Maximum open circuit voltage of 13.8 mV and power output as high as 15.6 µW cm-2 are reached in series and parallel configurations, respectively, operating upon thermal gradients generated with hot sources at 200 °C and air flows of 1.5 m s-1 . These results pave the way for direct application of SiGe nanowire-based micro-thermoelectric generators in the field of the Internet of Things.

SARS-CoV2/COVID-19 Infection in Transplant Recipients and in Patients on the Organ Transplant Waiting List in Colombia.

To assess our determination to continue transplant activity in Colombia during the coronavirus disease 2019 (COVID-19) pandemic, this study seeks to describe the risk of infection and mortality of transplanted patients vs those on the waiting list. Therefore, a descriptive study of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2)/COVID-19 infection in transplant recipients and patients on the waiting list was conducted. The data sources were the information systems of the Instituto Nacional de Salud of Colombia: National Donation and Transplant Information System, the National Public Health Surveillance System, and the National COVID-19 Data Repository. Characteristics of the patients who tested positive were analyzed, and the mortality rate was determined. An Real Time-PCR test for SARS-CoV-2/COVID-19 was performed in 7% of the transplant recipients included in this study, and 14.8% of those recipients tested positive. Among patients on the waiting list, 15.2% were tested, and 16.7% showed positive results. Overall, 1% (84/8108) of the transplant recipients and 2.5% (74/2926) of patients on the waiting list were infected with SARS-CoV-2/COVID-19. There were no differences in mortality between these groups (P = .8748). In conclusion, with the data obtained so far, the hospital availability, and the adoption of safety protocols in the institutions, our findings can support the continuity of the transplant activities in this country.

The Puerto Rico Alzheimer Disease Initiative (PRADI): A Multisource Ascertainment Approach.

INTRODUCTION: Puerto Ricans, the second largest Latino group in the continental US, are underrepresented in genomic studies of Alzheimer disease (AD). To increase representation of this group in genomic studies of AD, we developed a multisource ascertainment approach to enroll AD patients, and their family members living in Puerto Rico (PR) as part of the Alzheimer's Disease Sequencing Project (ADSP), an international effort to advance broader personalized/precision medicine initiatives for AD across all populations. METHODS: The Puerto Rico Alzheimer Disease Initiative (PRADI) multisource ascertainment approach was developed to recruit and enroll Puerto Rican adults aged 50 years and older for a genetic research study of AD, including individuals with cognitive decline (AD, mild cognitive impairment), their similarly, aged family members, and cognitively healthy unrelated individuals age 50 and up. Emphasizing identification and relationship building with key stakeholders, we conducted ascertainment across the island. In addition to reporting on PRADI ascertainment, we detail admixture analysis for our cohort by region, group differences in age of onset, cognitive level by region, and ascertainment source. RESULTS: We report on 674 individuals who met standard eligibility criteria [282 AD-affected participants (42% of the sample), 115 individuals with mild cognitive impairment (MCI) (17% of the sample), and 277 cognitively healthy individuals (41% of the sample)]. There are 43 possible multiplex families (10 families with 4 or more AD-affected members and 3 families with 3 AD-affected members). Most individuals in our cohort were ascertained from the Metro, Bayamón, and Caguas health regions. Across health regions, we found differences in ancestral backgrounds, and select clinical traits. DISCUSSION: The multisource ascertainment approach used in the PRADI study highlights the importance of enlisting a broad range of community resources and providers. Preliminary results provide important information about our cohort that will be useful as we move forward with ascertainment. We expect that results from the PRADI study will lead to a better understanding of genetic risk for AD among this population.

Towards femtosecond on-chip electronics based on plasmonic hot electron nano-emitters.

To combine the advantages of ultrafast femtosecond nano-optics with an on-chip communication scheme, optical signals with a frequency of several hundreds of THz need to be down-converted to coherent electronic signals propagating on-chip. So far, this has not been achieved because of the overall slow response time of nanoscale electronic circuits. Here, we demonstrate that 14 fs optical pulses in the near-infrared can drive electronic on-chip circuits with a prospective bandwidth up to 10 THz. The corresponding electronic pulses propagate in macroscopic striplines on a millimeter scale. We exploit femtosecond photoswitches based on asymmetric, nanoscale metal junctions to drive the pulses. The non-linear ultrafast response is based on a plasmonically enhanced, multiphoton absorption resulting in a field emission of ballistic hot electrons propagating across the nanoscale junctions. Our results pave the way towards femtosecond electronics integrated in wafer-scale THz circuits.

Choosing to engage and choosing to persist: The role of non-specific factors in health-promoting activities.

OBJECTIVE: Non-specific factors play an important role in determining benefits from health-promoting activities. Previous studies have focussed on beneficial outcomes of motivation during engagement. There are two aims of this project. First, we investigated whether expectancy and intrinsic motivation influence people's decisions to engage with health-promoting activities in the first instance and then subsequently adhere to them. Second, we examined the effects of providing information on health-promoting activities as a method of influencing expectancy and intrinsic motivation. METHOD: In two studies, participants were informed about a health-promoting activity (Study 1: A breathing exercise for well-being; Study 2: A gratitude exercise for smoking cessation) and told that it has either a 'known' or 'unknown' effectiveness. Participants were then given the opportunity to engage with the activity over the following days. Expectancy and intrinsic motivation were measured after reading the information and prior to engagement with the activity. Adherence to the activity was measured at follow-up. RESULTS: In both studies, intrinsic motivation positively predicted willingness to engage with the activities as well as subsequent adherence. Expectancy predicted adherence in Study 1 and choices to engage in Study 2, but not after controlling for intrinsic motivation. Describing the gratitude exercise as having a known effectiveness in Study 2 enhanced motivation and adherence to the activity. CONCLUSIONS: The non-specific benefit brought by intrinsic motivation plays an important role in choosing to engage with health-promoting activities as well as subsequent adherence. Our results also show that simple statements about the potential benefits of a health-promoting activity can motivate engagement and adherence. Statement of contribution What is already known on this subject? Previous studies have established that non-specific factors, namely expectancies and intrinsic motivation, play an important role in determining benefit when engaging in health-promoting activities. These studies have neglected how non-specific factors relate to initial choices to engage in health-promoting activities in the first instance. Intrinsic motivation has been found to be more strongly related to benefit than expectancies in real-world health-promoting activities. What does this study add? Intrinsic motivation predicts choices to engage with a health-promoting activity. Simple statements about benefits of a health-promoting activity motivate engagement.

Common Factor Mechanisms in Clinical Practice and Their Relationship with Outcome.

UNLABELLED: This study investigates three common factor mechanisms that could affect outcome in clinical practice: response expectancy, the affective expectation model and motivational concordance. Clients attending a gestalt therapy clinic (30 clients), a sophrology (therapeutic technique) clinic (33 clients) and a homeopathy clinic (31 clients) completed measures of expectancy and the Positive Affect and Negative Affect Schedule (PANAS) before their first session. After 1 month, they completed PANAS and measures of intrinsic motivation, perceived effort and empowerment. Expectancy was not associated with better outcome and was no different between treatments. Although some of the 54 clients who endorsed highest expectations showed substantial improvement, others did not: 19 had no change or deteriorated in positive affect, and 18 had the same result for negative affect. Intrinsic motivation independently predicted changes in negative affect (ß = -0.23). Intrinsic motivation (ß = 0.24), effort (ß = 0.23) and empowerment (ß = 0.20) independently predicted positive affect change. Expectancy (ß = -0.17) negatively affected changes in positive affect. Clients found gestalt and sophrology to be more intrinsically motivating, empowering and effortful compared with homeopathy. Greater improvement in mood was found for sophrology and gestalt than for homeopathy clients. These findings are inconsistent with response expectancy as a common factor mechanism in clinical practice. The results support motivational concordance (outcome influenced by the intrinsic enjoyment of the therapy) and the affective expectation model (high expectations can lead for some clients to worse outcome). When expectancy correlates with outcome in some other studies, this may be due to confound between expectancy and intrinsic enjoyment. KEY PRACTITIONER MESSAGE: Common factors play an important role in outcome. Intrinsic enjoyment of a therapeutic treatment is associated with better outcome. Active engagement with a therapeutic treatment improves outcome. Unrealistic expectations about a therapeutic treatment can have a negative impact on outcome.

Mood enhancement in health-promoting non-aerobic exercise: the role of non-specific mechanisms.

Eighty participants took part in a 5-day intervention Qi Gong study to enhance well-being and were randomised to either positive or body focus and either high or low hand position. The high hand position improved negative affect and was reported more intrinsically motivating but was unrelated to perceived effort. Positive focus produced better positive affect. For all groups combined, intrinsic motivation and effort predicted all three outcomes. The association between expectancy and perceived benefit was mediated via intrinsic motivation and perceived effort. Results support motivational concordance and positive focus as mechanisms of benefit but not response expectancy.

Caracterización clínica, epidemiológica e histopatológica de pacientes con diagnóstico de queratosis actínica / Clinical, epidemiological and histopathological characterization of patients with actinic keratosis

Introducción: en otros países se han descrito ciertos factores relacionados con el desarrollo de queratosis actínica (QA). Objetivo: describir las características clínicas, epidemiológicas e histopatológicas de pacientes institucionales de Medellín, con diagnóstico de QA. Metodología: estudio descriptivo de pacientes con QA. Se aplicó una encuesta estructurada tomando datos demográficos, clínicos y relacionados con el desarrollo de la QA. Resultados: se incluyeron 153 pacientes (58 hombres [37,9%] y 95 mujeres [62,1%]), con edad promedio de 70 años. Tenían 75 años o más 64 pacientes (41,8%). Ciento ocho pacientes (70,6%) refirieron haber tenido un grado alto de exposición solar en la niñez; 76 (49,7%) tenían el antecedente de fumar y 16 de estos (21,1%) aún fumaban; 46 (30,1%) informaron el antecedente de un familiar con cáncer de piel. Setenta y tres (47,7%) realizaban las actividades tanto bajo techo como al aire libre; 80 (52,3%) informaron que se aplicaban protector solar y 37 (24,4%) usaban gorra o sombrero por la época en que fueron encuestados. Predominó el fototipo II (101 pacientes; 66%) y había daño actínico moderado en 76 (49,7%). Cuando hubo un solo patrón histológico predominó el atrófico (12%) y cuando hubo dos, el atróficohiperqueratósico (18,7%). Conclusiones: las características fenotípicas y de exposición de los pacientes con QA estudiados en Medellín (Colombia) son similares a las reportadas en la literatura.

Introduction: Several factors related with the development of actinic keratosis (AK) have been reported in other countries. Objective: To describe the clinical, epidemiological and histopathological characteristics of patients with diagnosis of AK in Medellín, Colombia. Methodology: This was a descriptive study of patients with AK. A structured survey including demographic, clinical and epidemiological information was applied. Results: 153 patients were included (58 men [37.9%] and 95 women [62.1%]) with an average age of 70 years. Sixty four patients (41.8%) were aged 75 years or more. With regard to their personal history, 108 individuals (70.6%) had a high degree of solar exposure during childhood; 76 (49.7%) reported the habit of smoking and 16 out of these (21.1%) still smoked. In 46 (30.1%) there was a family history of skin cancer. Regarding individual habits, 73 (47.7%) carried out both indoor and outdoor activities, 80 (52.3%) reported the use of sunscreen and 37 (24.4%) used hat or cap at the time of the study. Fitzpatrick´s type II phototype predominated (101 patients; 66%) and 76 (49.7%) had moderate actinic damage. The predominant single histologic subtype corresponded to the atrophic type (12%) and the main mixed subtype was the atrophichyperkeratotic subtype (18.7%). Conclusions: Clinical, epidemiological and histopathological features found among two institutional populations with AK in Medellin (Colombia) were similar to those reported in the literature.

Nonspecific mechanisms that enhance well-being in health-promoting behaviors.

OBJECTIVE: We tested whether the nonspecific or placebo enhancement of well-being brought about by a health-promoting behavior was due to expectancy having an unmediated effect on outcome (response expectancy theory) or because expectancy was mediated through the behavioral and affective consequences of positively valued goal satisfaction (motivational concordance theory). METHOD: Fifty-seven participants completed a breathing exercise (a simplified Buteyko technique) purporting to enhance well-being over a period of 4 days. Participants were randomized to receive either easy or difficult task instructions. Expectancy was measured at baseline and perceived effort (as an indicator of motivation) and adherence were measured at follow-up. Well-being was measured by perceived change in well-being at follow-up and by change in the Positive and Negative Affect Scale between baseline and follow-up. RESULTS: Expectancy (r = .42), adherence (r = .57), and effort (r = .90) correlated with perceived benefit. Multiple regression and mediation analysis showed that effort predicted (p < .01) well-being independently of expectancy for all 3 measures of well-being, and that where expectancy predicted outcome, its effect was mediated by effort. Adherence failed to predict additional variance to outcome compared with effort and expectancy. CONCLUSION: These results are consistent with the hypothesis that placebo effects in therapeutic contexts are mediated via the affective consequences of performing a motivated ritual.

Psoriasis: revisión del tema con énfasis en la inmunopatogénesis / Psoriasis: a review with emphasis on immunopathogenesis

La psoriasis es una de las enfermedades cutáneas más frecuentes pues afecta al 2-3% de la población mundial. Es autoinmune, específica de órgano, crónica y recurrente, desencadenada por factores externos en individuos con predisposición genética. En su inmunopatogénesis se ha descrito unafalla en la regulación de la respuesta inmune frente a antígenos aún no bien identificados. Tiene diversas presentaciones clínicas e influye desfavorablemente en la calidad de vida de los pacientes. La comprensión de sus fundamentos inmunopatogénicos ha permitido poner en práctica nuevas estrategias de tratamiento como la terapia biológica. En este artículo se revisan los aspectos fundamentales de la inmunopatogénesis de la psoriasis y sus características epidemiológicas, clínicas e histopatológicas, así como las varias opciones terapéuticas.

Psoriasis is one of the most frequent skin diseases. Worldwide, it affects 2 to 3% of the population. It is an organ-specific, chronic, recurrent, autoimmune disease, triggered by external factors in individuals with a genetic predisposition. In its immunopathogenesis a lack of regulation of the immune response to unidentified antigens has been described. Psoriasis has many different clinical presentations and produces an important decrease in the quality of life. Understanding itsimmunopathogenetic bases has led to new therapeutic strategies such as the biological approaches. This review includes basic immunopathogenetic aspects of psoriasis, as well as the epidemiological, clinical and histopathological characteristics of the disease. Therapeutic options are also included.

Complicaciones pulmonares en malaria / Malaria pulmonary complications

La malaria es una de las enfermedades parasitarias más comunes en el mundo; anualmente afecta entre 200 y 300 millones de personas, con uno a dos millones de muertes debidas entre otras causas a las complicaciones agregadas, como malaria cerebral, disfunción hepática y renal, alteraciones metabólicas, hematológicas y pulmonares (1). Dentro de estas últimas, el síndrome de dificultad respiratoria aguda y el edema pulmonar, son manifestaciones que se presentan con una frecuencia de 3 por ciento a 10 por ciento en malaria por P. falciparum y por P. vivax, con una mortalidad que puede ascender al 40 por ciento (2). Se presentan dos casos de Síndrome de Dificultad Respiratoria Aguda y uno de edema pulmonar secundarios a malaria por P. falciparum y se revisan las complicaciones pulmonares en malaria, su definición, epidemiología, patogenia, criterios diagnósticos y su tratamiento

Trastornos de la alimentación: Su prevalencia y principales factores de riesgo - estudiantes universitarias de primer y segundo año / Eating disorders: Its prevalence and main risk factors – First and second year university female students

Antecedentes: El 95 por ciento de los trastornos de la alimentación se presenta en mujeres, siendo más frecuente en estudiantes de secundaria y universitarias, Su prevalencia en el mundo es el 0.5 al 1 por cinto para anorexia nerviosa y del 1 al 10 por ciento para bulimia. En Colombia es del 2.3 por ciento y 0.1 por ciento respectivamente, y no se conoce la prevalencia real para el trastorno de alimentación compulsiva. Dentro de la etiología, factores culturales como los medios de comunicación, presión social, estrés académico y otros desordenes mentales como depresión y ansiedad están fuertemente asociados."Objetivo": Calcular la prevalencia de los trastornos de alimentación y estimar su asociación con presión familiar, influencia de los medios de comunicación, estrés académico, depresión y ansiedad. Materiales y métodos: Estudio descriptivo realizado en 196 estudiantes universitarias de primer y segundo año en cuatro programas de pregrado del CES. Se aplicó un cuestionario con preguntas dirigidas a evaluar cada trastorno y factor de riesgo mencionado...