Direct-to-consumer, store-and-forward teledermatology with dermoscopy using the pharmacist as patient point-of-contact.

OBJECTIVE(S): To evaluate the frequency of nonmelanoma skin cancer (NMSC), NMSC precursors, and melanoma on a store-and-forward dermatology model featuring the pharmacist as the patient's point-of-contact. The secondary objective was to define lesion changes and symptoms perceived by patients (clinical prediction rules by nonexpert observers) that can be predictive of malignity. METHODS: A cross-sectional study of teledermatology consultation was performed. All patients who underwent a teledermatology consultation between September 2018 and March 2020 were included. A patient could have more than 1 lesion per consultation. The object of the study was a defined dermatologic lesion. The differences between the variables were analyzed using a univariate model based on the chi-square test for independent qualitative variables and Fisher exact test in cases when the expected values in any of the cells of a contingency table were less than 5. Statistical significance was set at P < 0.05 (2-tailed). RESULTS: A total of 225 lesions in 218 patients were considered for this study; 53.8% (n = 121) of the lesions were classified as benign, 16.4% (n = 37) as dubious, 23.1% (n = 52) as NMSC precursors, 5.8% (n = 13) as NMSC, and 0.9% (n = 2) as melanomas. Of the reported clinical lesion changes, spontaneous pain, pruritus, surface texture changes, color changes, or form changes had no statistically significant relationship with the diagnostic group, whereas the presence of spontaneous bleeding (P = 0.015) and size changes (P = 0.026) were more frequently observed in the "dubious lesion" and "of oncological relevance lesion" groups. CONCLUSION: This "direct-to-consumer," store-and-forward teledermatology with dermoscopy model featuring the pharmacist as the patient's point-of-contact is useful for the diagnosis of melanoma, NMSC, and NMSC precursors when backed by a robust dermatology service.

[COVID-19 and psychological behavior: a systematic review of the psychological effects of 21st century pandemics]. / COVID-19 y comportamiento psicológico: revisión sistemática de los efectos psicológicos de las pandemias del siglo XXI.

The aim of this work was to conduct a systematic review on psychological behavior in the context of pandemic scenarios during the twenty-first century. We focused on empirical works and brief case reports of H1N1 flu and COVID-19. Our review included 32 papers published both in English or Spanish. We built a set of tables that allowed us to classify the information in four main categories, namely the psychological impact of the pandemic, whether people follow or not official measures to protect themselves against the pandemic, psychological adherence considerations implied as mediators to respect official strategies, and relevant methodological characteristics of the pandemic research. Results show that there are significant impacts on the psychological behavior of people, social groups and organizations in several dimensions, namely emotion, cognition, behavior, mental health, organization and psychosocial factors. In addition, we found that certain social groups experienced a critical psychosocial impact likely due to the pandemic. Psychosocial factors affecting adherence were also identified, which allow us to better understand how health strategies are followed by the population. Different psychosocial suggestions, which emerged from the papers reviewed, were systematized and should be considered as possible pandemic strategies to be implemented.

Development and validation of a questionnaire to measure empowerment in adult patients with atopic dermatitis. The DATEMP questionnaire.

BACKGROUND AND OBJECTIVES: In recent years, the hypothesis that increasing the empowerment of patients can help to improve health outcomes and rationalize the use of health services has become relevant, especially for chronic diseases. Developing validated measurement tools is necessary to achieve this goal. In the field of dermatology, there are few studies related to empowerment of the patient. The aim of the present research is to develop and validate a self-administered questionnaire for adult patients diagnosed with atopic dermatitis (AD) in order to measure their level of empowerment. METHODS: After a literature review and the establishment of consulting groups of patients and dermatologists, a large battery of 35 items was generated, based on the dimensions included in previous empowerment descriptions. A multidisciplinary group selected the 20 most suitable items to include in the questionnaire. A cross-sectional study was carried out with the items included in the questionnaire as well as demographic and clinical characteristics. To reduce the number of items and measure the construct validity, an exploratory factorial analysis (EFA) of the primary components and varimax rotation were used. Cronbach's α was used to measure the reliability of the individual scales and the global questionnaire. RESULTS: 242 valid questionnaires were included. After completion of the EFA, the final Dermatitis Atópica EMPoderamiento (DATEMP) questionnaire was composed of 17 items that converged on four factors. The four scales had adequate reliability: "Knowledge" (Cronbach's alpha = 0.808), "Abilities" (Cronbach's alpha = 0.744), "Intention to change" (Cronbach's alpha = 0.798) and "Coping skills" (Cronbach's alpha = 0.772). The overall Cronbach's α of the questionnaire was 0.764. CONCLUSIONS: The DATEMP questionnaire is the first specific empowerment measurement instrument developed for patients with AD that has demonstrated adequate levels of reliability and construct validity. It is a self-administered questionnaire that is simple and quick to answer.

Subjective theories about parental discipline in parenting literature. / Teorías subjetivas sobre disciplina parental en literatura para padres.

INTRODUCTION: Parental discipline is a topic frequently asked for advice by those who consult health professionals. It is related to parenting styles and has been scientifically studied regarding its effective ness and impact on children. OBJECTIVE: To describe the subjective theories about parental discipline present in recommendations made by doctors and psychologists in books for parents in Spanish. Ma terial and Method: Thirteen books with advice for parents, written in Spanish by healthcare profes sionals published between 2000 and 2017 were analyzed. Data analysis was performed using Groun ded Theory procedures adapted for the study of subjective theories, through open and axial coding. In addition, thematic codification was made to describe the cases, identifying subjective mottos and subjective theories for each case, which at the same time were grouped into superordinate subjective theories. RESULTS: The data were grouped into three general subjective theories about parental dis cipline in the books analyzed. These subjective theories differ from one another in the importance attributed to authority, punishment, and the necessity of parental discipline. CONCLUSION: There are differences in parental discipline among the books. There is little scientific evidence on the subjective theories of the books. Results differ from historical analyses of these publications in other cultural and temporal contexts. The importance of developing practical guidelines on parental discipline ba sed on evidence to guide parents by health professionals is highlighted.

"Sky Full of Stars" Pattern: Dermoscopic Findings in a Desmoplastic Giant Congenital Melanocytic Nevus.

Desmoplastic giant congenital melanocytic nevus (DGCN) is an uncommon variant of congenital nevus, presenting as a progressive induration and hypopigmentation of the lesion that occasionally causes hair loss and even total or partial disappearance of the nevus. A 6-month-old girl with a giant congenital melanocytic nevus that involved the entire posterior side of the right thigh was seen in our department. Nine months later, the peripheral area of the nevus presented as a marked induration with hypopigmentation. Dermoscopy demonstrated a reticular pattern exclusively located in the perifollicular areas, with a radial distribution from the follicular ostium that mimicked a "sky full of stars." We report a case of DGCN, including a dermoscopic description of the findings noted in the indurated and hypopigmented areas that appear as a "sky full of stars" image.

Ultrabroadband high-resolution silicon RF-photonic beamformer.

Microwave photonics aims to overcome the limitations of radiofrequency devices and systems by leveraging the unique properties of optics in terms of low loss and power consumption, broadband operation, immunity to interference and tunability. This enables versatile functions like beam steering, crucial in emerging applications such as the Internet of Things (IoT) and 5/6G networks. The main problem with current photonic beamforming architectures is that there is a tradeoff between resolution and bandwidth, which has not yet been solved. Here we propose and experimentally demonstrate a novel switched optical delay line beamformer architecture that is capable of achieving the desired maximum resolution (i.e., 2M pointing angles for M-bit coding) and provides broadband operation simultaneously. The concept is demonstrated by means of a compact (8 × 3 mm2) 8 (5-bit) delay line Silicon Photonic chip implementation capable of addressing 32 pointing angles and offering 20 GHz bandwidth operation.

3D DVH-based metric analysis versus per-beam planar analysis in IMRT pretreatment verification.

PURPOSE: To evaluate methods of pretreatment IMRT analysis, using real measurements performed with a commercial 2D detector array, for clinical relevance and accuracy by comparing clinical DVH parameters. METHODS: We divided the work into two parts. The first part consisted of six in-phantom tests aimed to study the sensitivity of the different analysis methods. Beam fluences, 3D dose distribution, and DVH of an unaltered original plan were compared to those of the delivered plan, in which an error had been intentionally introduced. The second part consisted of comparing gamma analysis with DVH metrics for 17 patient plans from various sites. Beam fluences were measured with the MapCHECK 2 detector, per-beam planar analysis was performed with the MapCHECK software, and 3D gamma analysis and the DVH evaluation were performed using 3DVH software. RESULTS: In a per-beam gamma analysis some of the tests yielded false positives or false negatives. However, the 3DVH software correctly described the DVH of the plan which included the error. The measured DVH from the plan with controlled error agreed with the planned DVH within 2% dose or 2% volume. We also found that a gamma criterion of 3%∕3 mm was too lax to detect some of the forced errors. Global analysis masked some problems, while local analysis magnified irrelevant errors at low doses. Small hotspots were missed for all metrics due to the spatial resolution of the detector panel. DVH analysis for patient plans revealed small differences between treatment plan calculations and 3DVH results, with the exception of very small volume structures such as the eyes and the lenses. Target coverage (D(98) and D(95)) of the measured plan was systematically lower than that predicted by the treatment planning system, while other DVH characteristics varied depending on the parameter and organ. CONCLUSIONS: We found no correlation between the gamma index and the clinical impact of a discrepancy for any of the gamma index evaluation possibilities (global, local, 2D, or 3D). Some of the tests yielded false positives or false negatives in a per-beam gamma analysis. However, they were correctly accounted for in a DVH analysis. We also showed that 3DVH software is reliable for our tests, and is a viable method for correlating planar discrepancies with clinical relevance by comparing the measured DVH of target and OAR's with clinical tolerance.

Crosslinking of membrane CD13 in human neutrophils mediates phagocytosis and production of reactive oxygen species, neutrophil extracellular traps and proinflammatory cytokines.

Aminopeptidase N, or CD13, is a cell membrane ectopeptidase highly expressed in myeloid cells. Through its enzymatic activity, CD13 regulates the activity of several bioactive peptides, such as endorphins and enkephalins, chemotactic peptides like MCP-1 and IL-8, angiotensin III, bradikinin, etc. In recent years, it has been appreciated that independently of its peptidase activity, CD13 can activate signal transduction pathways and mediate effector functions such as phagocytosis and cytokine secretion in monocytes and macrophages. Although neutrophils are known to express CD13 on its membrane, it is currently unknown if CD13 can mediate effector functions in these cells. Here, we show that in human neutrophils CD13 can mediate phagocytosis, which is dependent on a signaling pathway that involves Syk, and PI3-K. Phagocytosis mediated by CD13 is associated with production of reactive oxygen species (ROS). The level of phagocytosis and ROS production mediated by CD13 are similar to those through FcγRIII (CD16b), a widely studied receptor of human neutrophils. Also, CD13 ligation induces the release of neutrophil extracellular traps (NETs) as well as cytokine secretion from neutrophils. These results support the hypothesis that CD13 is a membrane receptor able to activate effector functions in human neutrophils.

Establishment and validation of surface model for biodosimetry based on γ-H2AX foci detection.

INTRODUCTION: In the event of a radiation accident detecting γ-H2AX foci is being accepted as fast method for triage and dose assessment. However, due to their disappearance kinetics, published calibrations have been constructed at specific post-irradiation times. OBJECTIVES: To develop a surface, or tridimensional, model to estimate doses at times not included in the calibration analysis, and to validate it. MATERIALS AND METHODS: Calibration data was obtained irradiating peripheral mononucleated cells from one donor with radiation doses ranging from 0 to 3 Gy, and γ -H2AX foci were detected microscopically using a semi-automatic method, at different post-irradiation times from 0.5 to 24 h. For validation, in addition to the above-mentioned donor, blood samples from another donor were also used. Validation was done within the range of doses and post-irradiation times used in the calibration. RESULTS: The calibration data clearly shows that at each analyzed time, the γ-H2AX foci frequency increases as dose increases, and for each dose this frequency decreases with post-irradiation time. The γ-H2AX foci nucleus distribution was clearly overdispersed, for this reason to obtain bidimensional and tridimensional dose-effect relationships no probability distribution was assumed, and linear and non-linear least squares weighted regression was used. In the two validation exercises for most evaluated samples, the 95% confidence limits of the estimated dose were between ±0.5 Gy of the real dose. No major differences were observed between donors. CONCLUSION: In case of a suspected overexposure to radiation, the surface model here presented allows a correct dose estimation using γ-H2AX foci as biomarker. The advantage of this surface model is that it can be used at any post-irradiation time, in our model between 0.5 and 24 h.

Ionizing radiation or mitomycin-induced micronuclei in lymphocytes of BRCA1 or BRCA2 mutation carriers.

BRCA1 and BRCA2 genes are essential in preserving the integrity of genome, and it is not unambiguously clear whether the heterozygosity status may affect BRCA1 or BRCA2 functions. This may have implications for the clinical management of BRCA1 and BRCA2 mutation carriers both in breast cancer (BC) screening modality and in cancer treatment based on DNA-damaging or DNA-repair-inhibiting drugs. We investigated whether lymphocytes carrying BRCA1 or BRCA2 mutations displayed an increased sensitivity to radiation or mitomycin C (MMC) in vitro treatments. Peripheral blood from 21 BRCA1 mutation carriers (12 with BC and 9 healthy), 24 BRCA2 carriers (13 with BC and 11 healthy), 15 familial BC patients without detected mutation in BRCA1 or BRCA2 and 16 controls without familial history of cancer (5 with BC and 11 healthy) were irradiated or treated with MMC. Chromosomal damage was measured using the cytokinesis-block micronucleus assay. We evaluated micronuclei (MN) and nucleoplasmic bridges (NPBs). The BRCA2 mutation carriers and familial BC patients without detected mutation in BRCA1 or BRCA2 showed less basal NPB than BRCA1 carriers and controls. The BRCA1 (+/-) or BRCA2 (+/-) lymphocytes did not have increased frequencies of MN or NPB after irradiation. In contrast, BRCA2 (+/-) lymphocytes presented higher levels of MN after MMC exposure than BRCA1 carriers and controls. The monoallelic BRCA1 or BRCA2 pathogenic mutations seem not to be associated with an enhanced radiosensitivity. The mutation of one BRCA2 allele conferred an increased sensitivity to MMC, presumably because of the role of this gene in the repair of MMC-induced DNA damage. This finding indicates that the MMC-induced MN analysis could be useful in identifying functional deficiencies of BRCA2 or genes related to BRCA2. Since MMC can be used as an anti-cancer drug, these data may be relevant for the management and follow-up of BRCA2 mutation carriers.

Radiation dose assessment in a 320-detector-row CT scanner used in cardiac imaging.

PURPOSE: In the present era of cone-beam CT scanners, the use of the standardized CTDI100 as a surrogate of the idealized CTDI is strongly discouraged and, consequently, so should be the use of the dose-length product (DLP) as an estimate of the total energy imparted to the patient. However, the DLP is still widely used as a reference quantity to normalize the effective dose for a given scan protocol mainly because the CTDI100 is an easy-to-measure quantity. The aim of this article is therefore to describe a method for radiation dose assessment in large cone-beam single axial scans, which leads to a straightforward estimation of the total energy imparted to the patient. The authors developed a method accessible to all medical physicists and easy to implement in clinical practice in an attempt to update the bridge between CT dosimetry and the estimation of the effective dose. METHODS: The authors used commercially available material and a simple mathematical model. The method described herein is based on the dosimetry paradigm introduced by the AAPM Task Group 111. It consists of measuring the dose profiles at the center and the periphery of a long body phantom with a commercial solid-state detector. A weighted dose profile is then calculated from these measurements. To calculate the CT dosimetric quantities analytically, a Gaussian function was fitted to the dose profile data. Furthermore, the Gaussian model has the power to condense the z-axis information of the dose profile in two parameters: The single-scan central dose, f(0), and the width of the profile, sigma. To check the energy dependence of the solid-state detector, the authors compared the dose profiles to measurements made with a small volume ion chamber. To validate the overall method, the authors compared the CTDI100 calculated analytically to the measurement made with a 100 mm pencil ion chamber. RESULTS: For the central and weighted dose profiles, the authors found a good agreement between the measured dose profile data and the fitted Gaussian functions. The solid-state detector had no energy dependence--within the energy range of interest--and the analytical model succeeded in reproducing the absolute dose values obtained with the pencil ion chamber. For the case of large cone-beam single axial scans, the quantity that better characterizes the total energy imparted to the patient is the weighted dose profile integral (DPI(w)). The DPI(w) can be easily determined from the two parameters that define the Gaussian functions: f(0) and sigma. The authors found that the DLP underestimated the total energy imparted to the patient by more than 20%. The authors also found that the calculated CT dosimetric quantities were higher than those displayed on the scanner console. CONCLUSIONS: The authors described and validated a method to assess radiation dose in large cone-beam single axial scans. This method offers a simple and more accurate estimation of the total energy imparted to the patient, thus offering the possibility to update the bridge between CT dosimetry and the estimation of the effective dose for cone-beam CT examinations in radiology, nuclear medicine, and radiation therapy.

Neutrophils: Many Ways to Die.

Neutrophils or polymorphonuclear leukocytes (PMN) are key participants in the innate immune response for their ability to execute different effector functions. These cells express a vast array of membrane receptors that allow them to recognize and eliminate infectious agents effectively and respond appropriately to microenvironmental stimuli that regulate neutrophil functions, such as activation, migration, generation of reactive oxygen species, formation of neutrophil extracellular traps, and mediator secretion, among others. Currently, it has been realized that activated neutrophils can accomplish their effector functions and simultaneously activate mechanisms of cell death in response to different intracellular or extracellular factors. Although several studies have revealed similarities between the mechanisms of cell death of neutrophils and other cell types, neutrophils have distinctive properties, such as a high production of reactive oxygen species (ROS) and nitrogen species (RNS), that are important for their effector function in infections and pathologies such as cancer, autoimmune diseases, and immunodeficiencies, influencing their cell death mechanisms. The present work offers a synthesis of the conditions and molecules implicated in the regulation and activation of the processes of neutrophil death: apoptosis, autophagy, pyroptosis, necroptosis, NETosis, and necrosis. This information allows to understand the duality encountered by PMNs upon activation. The effector functions are carried out to eliminate invading pathogens, but in several instances, these functions involve activation of signaling cascades that culminate in the death of the neutrophil. This process guarantees the correct elimination of pathogenic agents, damaged or senescent cells, and the timely resolution of the inflammation that is essential for the maintenance of homeostasis in the organism. In addition, they alert the organism when the immunological system is being deregulated, promoting the activation of other cells of the immune system, such as B and T lymphocytes, which produce cytokines that potentiate the microbicide functions.

Mortality associated with non-melanoma skin cancer in Spain from 1979 to 2018: trends and age-adjusted rates.

Non-melanoma skin cancers (NMSCs) are the most frequent group of malignant tumours worldwide. Objectives: The aim of the present research was to analyse mortality associated with NMSC in Spain between 1979 and 2018 and highlight changes regarding trend in mortality and differences according to age groups and gender. Death records and mid-year population data were collected from the National Statistics Institute. Age-standardized mortality rates were calculated. Significant changes in mortality trends were identified using Joinpoint regression. The independent effects of age, period and cohort and potential years of life lost due to NMSC were also analysed. Mortality rates associated with NMSC in Spain were reported as 2.49 per 100,000 inhabitants in 1979 (95% CI: 2.24-2.77) and 1.27 per 100,000 inhabitants in 2018 (95% CI; 1.16-1.39) for the overall population. Women who were born after the 70 s showed a significant increase in relative risk of death due to NMSC. Mortality associated with NMSC in Spain shows a decreasing overall trend that appears to have stabilized since 2005, with the exception of women between 35 and 64 years old.

Intraoperative Ketamine and Magnesium Therapy to Control Postoperative Pain After Abdominoplasty and/or Liposuction: A Clinical Randomized Trial.

PURPOSE: This study aimed to compare the effects of ketamine and ketamine associated with magnesium on opioid consumption and pain scores in patients undergoing abdominoplasty and/or liposuction compared to standard treatment. PATIENTS AND METHODS: A total of 63 patients were included and randomized as follows: 21 patients in the Control group, 20 patients in the Ketamine group (Ket), and 22 patients in the Ketamine-magnesium group (KetMag). The KetMag group received an IV bolus of 0.3 mg/kg of ketamine and 50 mg/kg magnesium, followed by continuous infusion of ketamine (0.15 mg/kg/h) and magnesium (10 mg/kg/h) until extubation. The Ket group received the same bolus and infusion of ketamine, together with a bolus and continuous infusion of placebo instead of magnesium. The Control group received saline instead of ketamine and magnesium. The groups were compared in morphine consumption during the first 12h, body-postoperative pain and disability scale until the 90th day, the time until the first morphine request on the PCA pump, pain scores, and the adverse effects related to the use of study drugs. RESULTS: The KetMag group had a lower morphine consumption by almost 50% during the first 12h than the Control and the Ket groups. In addition, the KetMag group required the first dose of morphine later than the other two groups. There were no differences in the adverse effects of the proposed treatments. Finally, multiple linear regression and a nonlinear approach analysis indicated that the Control group experienced a higher degree of pain and increased morphine consumption per hour than Ket and KetMag groups. CONCLUSION: Co-administration of intraoperative ketamine plus magnesium and ketamine alone are an effective and easy regime for reducing pain and opioid consumption in the postoperative period.

Pseudo skin flash on VMAT in breast radiotherapy: Optimization of virtual bolus thickness and HU values.

PURPOSE: Optimisation strategies for volumetric modulated arc therapy (VMAT) in most treatment planning systems for breast cancer do not account for patient positioning, breathing, or anatomical changes. To overcome this limitation, a pseudo-skin flash strategy using a virtual bolus has been proposed. Using this strategy, we determined optimal thickness and value of Hounsfield units (HU) assigned to the virtual bolus to ensure adequate CTV irradiation. MATERIALS AND METHODS: We modified the original computed tomography data (CT0) by adding combinations of thicknesses and densities of a virtual bolus on PTVs (CT') of seven bilateral breast cancer patients. Using a single optimization objective template, we obtained a VMAT plan on CT' and recalculated this on the CT0. Optimal CT' parameters were defined as those that minimized dose differences between CT' and CT0 plans regarding PTV and OAR dose-volume parameters. We studied bolus parameters regarding robustness by shifting the isocenter 5 and 10 mm in the breathing direction for each CT0 plan. RESULTS: The minimal dosimetric impact was between -400 and -600 HU depending on bolus thickness. OARs doses were not significantly affected. Best robustness was found for -500 HU and 15 mm bolus thickness against shifts of up to 10 mm in the breathing direction. CONCLUSION: Our results support a bolus thickness equal to the CTV-PTV margin plus 5 mm and a virtual bolus HU value around -500 and -400 depending on the bolus thickness chosen. These findings could play a useful role in maximisingrobustness and minimising the need for plan renormalization.

Representaciones sociales acerca de Instagram: Estudio cualitativo con adultos emergentes con diferente bienestar psicológico y autoestima corporal

Antecedentes existe una relación entre el uso de Instagram y diferentes influencias e interacciones con el bienestar y salud mental de este grupo etario. Objetivo Reconstruir las representaciones sociales acerca de la red social Instagram de adultos emergentes con diferentes niveles de bienestar psicológico y autoestima corporal. Método redes semánticas naturales y entrevistas semiestructuradas fueron aplicadas a N=12 adultos emergentes (19 - 27 años) divididos en dos grupos según sus niveles de autoestima corporal y bienestar psicológico. El análisis de datos estuvo basado en análisis de redes semánticas naturales y algunos procedimientos de codificación teórica. Resultados se muestra la presencia del concepto de "acoso" como núcleo central de la representación social de Instagram en el grupo con baja autoestima corporal y bajo bienestar psicológico, a diferencia del grupo con alta autoestima corporal y alto bienestar psicológico en donde el núcleo central fue "red social". Conclusiones en los grupos estudiados, se encontraron dos representaciones sociales diferentes respecto de Instagram. Estos resultados pueden ser relevantes para aportar a llenar el vacío de conocimiento sobre los significados subjetivos colectivos de los adultos emergentes, teniendo implicancias en la mejor comprensión de las diversas formas de relación que establecen con esta y otras redes sociales.

Background There is a relationship between the use of Instagram and various influences and interactions with the well-being and mental health of this age group. Objective To reconstruct the social representations of the Instagram social network among emerging adults with different levels of psychological well-being and body esteem. Method Natural semantic networks and semi-structured interviews were conducted with N=12 emerging adults (19 - 27 years old) divided into two groups based on their body self-esteem and psychological well-being levels. Data analysis relied on natural semantic network analysis and theoretical coding. Results The concept of "harassment" is revealed as the central core of the social representation of Instagram in the group with low body self-esteem and low psychological well-being, unlike the group with high body esteem and high psychological well-being where the central core was the "social network" itself. Conclusions Two different social representations of Instagram were found in the studied groups. These results could contribute to filling the knowledge gap about the collective subjective meanings of emerging adults, impacting the better understanding of the diverse relationships they establish with this and other social networks.

Monte Carlo based water/medium stopping-power ratios for various ICRP and ICRU tissues.

Water/medium stopping-power ratios, s(w,m), have been calculated for several ICRP and ICRU tissues, namely adipose tissue, brain, cortical bone, liver, lung (deflated and inflated) and spongiosa. The considered clinical beams were 6 and 18 MV x-rays and the field size was 10 x 10 cm(2). Fluence distributions were scored at a depth of 10 cm using the Monte Carlo code PENELOPE. The collision stopping powers for the studied tissues were evaluated employing the formalism of ICRU Report 37 (1984 Stopping Powers for Electrons and Positrons (Bethesda, MD: ICRU)). The Bragg-Gray values of s(w,m) calculated with these ingredients range from about 0.98 (adipose tissue) to nearly 1.14 (cortical bone), displaying a rather small variation with beam quality. Excellent agreement, to within 0.1%, is found with stopping-power ratios reported by Siebers et al (2000a Phys. Med. Biol. 45 983-95) for cortical bone, inflated lung and spongiosa. In the case of cortical bone, s(w,m) changes approximately 2% when either ICRP or ICRU compositions are adopted, whereas the stopping-power ratios of lung, brain and adipose tissue are less sensitive to the selected composition. The mass density of lung also influences the calculated values of s(w,m), reducing them by around 1% (6 MV) and 2% (18 MV) when going from deflated to inflated lung.

Monte Carlo simulation of MOSFET detectors for high-energy photon beams using the PENELOPE code.

The aim of this work was the Monte Carlo (MC) simulation of the response of commercially available dosimeters based on metal oxide semiconductor field effect transistors (MOSFETs) for radiotherapeutic photon beams using the PENELOPE code. The studied Thomson&Nielsen TN-502-RD MOSFETs have a very small sensitive area of 0.04 mm(2) and a thickness of 0.5 microm which is placed on a flat kapton base and covered by a rounded layer of black epoxy resin. The influence of different metallic and Plastic water build-up caps, together with the orientation of the detector have been investigated for the specific application of MOSFET detectors for entrance in vivo dosimetry. Additionally, the energy dependence of MOSFET detectors for different high-energy photon beams (with energy >1.25 MeV) has been calculated. Calculations were carried out for simulated 6 MV and 18 MV x-ray beams generated by a Varian Clinac 1800 linear accelerator, a Co-60 photon beam from a Theratron 780 unit, and monoenergetic photon beams ranging from 2 MeV to 10 MeV. The results of the validation of the simulated photon beams show that the average difference between MC results and reference data is negligible, within 0.3%. MC simulated results of the effect of the build-up caps on the MOSFET response are in good agreement with experimental measurements, within the uncertainties. In particular, for the 18 MV photon beam the response of the detectors under a tungsten cap is 48% higher than for a 2 cm Plastic water cap and approximately 26% higher when a brass cap is used. This effect is demonstrated to be caused by positron production in the build-up caps of higher atomic number. This work also shows that the MOSFET detectors produce a higher signal when their rounded side is facing the beam (up to 6%) and that there is a significant variation (up to 50%) in the response of the MOSFET for photon energies in the studied energy range. All the results have shown that the PENELOPE code system can successfully reproduce the response of a detector with such a small active area.