Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 247
Filtrar
1.
Phys Rev Lett ; 132(17): 172302, 2024 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-38728735

RESUMEN

This Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at sqrt[s]=13 TeV. Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of 1.4<|Δη|<1.8 and a transverse momentum of 1

2.
Phys Rev Lett ; 132(16): 162302, 2024 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-38701458

RESUMEN

The first measurement of the cross section for incoherent photonuclear production of J/ψ vector mesons as a function of the Mandelstam |t| variable is presented. The measurement was carried out with the ALICE detector at midrapidity, |y|<0.8, using ultraperipheral collisions of Pb nuclei at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=5.02 TeV. This rapidity interval corresponds to a Bjorken-x range (0.3-1.4)×10^{-3}. Cross sections are given in five |t| intervals in the range 0.04<|t|<1 GeV^{2} and compared to the predictions by different models. Models that ignore quantum fluctuations of the gluon density in the colliding hadron predict a |t| dependence of the cross section much steeper than in data. The inclusion of such fluctuations in the same models provides a better description of the data.

3.
Hear Res ; 447: 109008, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38636186

RESUMEN

The auditory cortex is the source of descending connections providing contextual feedback for auditory signal processing at almost all levels of the lemniscal auditory pathway. Such feedback is essential for cognitive processing. It is likely that corticofugal pathways are degraded with aging, becoming important players in age-related hearing loss and, by extension, in cognitive decline. We are testing the hypothesis that surface, epidural stimulation of the auditory cortex during aging may regulate the activity of corticofugal pathways, resulting in modulation of central and peripheral traits of auditory aging. Increased auditory thresholds during ongoing age-related hearing loss in the rat are attenuated after two weeks of epidural stimulation with direct current applied to the surface of the auditory cortex for two weeks in alternate days (Fernández del Campo et al., 2024). Here we report that the same cortical electrical stimulation protocol induces structural and cytochemical changes in the aging cochlea and auditory brainstem, which may underlie recovery of age-degraded auditory sensitivity. Specifically, we found that in 18 month-old rats after two weeks of cortical electrical stimulation there is, relative to age-matched non-stimulated rats: a) a larger number of choline acetyltransferase immunoreactive neuronal cell body profiles in the ventral nucleus of the trapezoid body, originating the medial olivocochlear system.; b) a reduction of age-related dystrophic changes in the stria vascularis; c) diminished immunoreactivity for the pro-inflammatory cytokine TNFα in the stria vascularis and spiral ligament. d) diminished immunoreactivity for Iba1 and changes in the morphology of Iba1 immunoreactive cells in the lateral wall, suggesting reduced activation of macrophage/microglia; d) Increased immunoreactivity levels for calretinin in spiral ganglion neurons, suggesting excitability modulation by corticofugal stimulation. Altogether, these findings support that non-invasive neuromodulation of the auditory cortex during aging preserves the cochlear efferent system and ameliorates cochlear aging traits, including stria vascularis dystrophy, dysregulated inflammation and altered excitability in primary auditory neurons.


Asunto(s)
Envejecimiento , Corteza Auditiva , Vías Auditivas , Cóclea , Estimulación Eléctrica , Presbiacusia , Animales , Corteza Auditiva/metabolismo , Corteza Auditiva/fisiopatología , Cóclea/inervación , Cóclea/metabolismo , Cóclea/fisiopatología , Cóclea/patología , Presbiacusia/fisiopatología , Presbiacusia/metabolismo , Presbiacusia/patología , Vías Auditivas/fisiopatología , Vías Auditivas/metabolismo , Masculino , Envejecimiento/patología , Envejecimiento/metabolismo , Modelos Animales de Enfermedad , Factores de Edad , Neuronas Eferentes/metabolismo , Microglía/metabolismo , Microglía/patología , Umbral Auditivo , Colina O-Acetiltransferasa/metabolismo , Núcleo Olivar/metabolismo , Potenciales Evocados Auditivos del Tronco Encefálico , Audición , Ratas Sprague-Dawley , Factor de Necrosis Tumoral alfa/metabolismo , Proteínas de Unión al Calcio , Proteínas de Microfilamentos
4.
Khirurgiia (Mosk) ; (3): 54-62, 2024.
Artículo en Ruso | MEDLINE | ID: mdl-38477244

RESUMEN

OBJECTIVE: To determine if laparoscopic excision is more effective than open excision in the treatment of choledochal cysts. MATERIAL AND METHODS: A systematic review of randomized clinical trials in 3 databases measuring the efficacy of laparoscopic and open excision of choledochal cysts was performed. The authors considered international and national reports, whose results were analyzed in detail. RESULTS: Mean duration of laparoscopic excision was 51 min, open excision - 35.4 min. Length of hospital-stay after laparoscopic excision ranged between 5 and 74 days, after open excision - between 7 and 146 days. Bile leakage rate was 1-2% and 4%, respectively. Laparoscopic excision was followed by lower complication rate. Morbidity and mortality in laparoscopic excision was 20% and 0%, in open excision - 60% and 3.3%, respectively. CONCLUSION: Laparoscopic excision is more effective than open excision in the treatment of choledochal cysts.


Asunto(s)
Procedimientos Quirúrgicos del Sistema Biliar , Quiste del Colédoco , Laparoscopía , Humanos , Quiste del Colédoco/cirugía , Resultado del Tratamiento , Estudios Retrospectivos , Laparoscopía/métodos , Procedimientos Quirúrgicos del Sistema Biliar/métodos
5.
Hear Res ; 444: 108969, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38350175

RESUMEN

Presbycusis or age-related hearing loss (ARHL) is one of the most prevalent chronic health problems facing aging populations. Along the auditory pathway, the stations involved in transmission and processing, function as a system of interconnected feedback loops. Regulating hierarchically auditory processing, auditory cortex (AC) neuromodulation can, accordingly, activate both peripheral and central plasticity after hearing loss. However, previous ARHL-prevention interventions have mainly focused on preserving the structural and functional integrity of the inner ear, overlooking the central auditory system. In this study, using an animal model of spontaneous ARHL, we aim at assessing the effects of multisession epidural direct current stimulation of the AC through stereotaxic implantation of a 1-mm silver ball anode in Wistar rats. Consisting of 7 sessions (0.1 mA/10 min), on alternate days, in awake animals, our stimulation protocol was applied at the onset of hearing loss (threshold shift detection at 16 months). Click- and pure-tone auditory brainstem responses (ABRs) were analyzed in two animal groups, namely electrically stimulated (ES) and non-stimulated (NES) sham controls, comparing recordings at 18 months of age. At 18 months, NES animals showed significantly increased threshold shifts, decreased wave amplitudes, and increased wave latencies after click and tonal ABRs, reflecting a significant, spontaneous ARHL evolution. Conversely, in ES animals, no significant differences were detected in any of these parameters when comparing 16 and 18 months ABRs, indicating a delay in ARHL progression. Electrode placement in the auditory cortex was accurate, and the stimulation did not cause significant damage, as shown by the limited presence of superficial reactive microglial cells after IBA1 immunostaining. In conclusion, multisession DC stimulation of the AC has a protective effect on auditory function, delaying the progression of presbycusis.


Asunto(s)
Corteza Auditiva , Presbiacusia , Ratas , Animales , Presbiacusia/prevención & control , Ratas Wistar , Envejecimiento/fisiología , Audición , Potenciales Evocados Auditivos del Tronco Encefálico/fisiología , Umbral Auditivo/fisiología
6.
Respir Med ; 217: 107362, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37451648

RESUMEN

INTRODUCTION: One of the major concerns with post-acute sequelae of COVID-19 (PASC) is the development of pulmonary fibrosis, for which no approved pharmacological treatment exists. Therefore, the primary aim of this open-label study was to evaluate the safety and the potential clinical efficacy of a prolonged-release pirfenidone formulation (PR-PFD) in patients having PASC-pulmonary fibrosis. METHODS: Patients with PASC-pulmonary fibrosis received PR-PFD 1800 mg/day (1200 mg in the morning after breakfast and 600 mg in the evening after dinner) for three months. Blood samples were taken to confirm the pharmacokinetics of PR-PFD, and adverse events (AEs) were evaluated monthly using a short questionnaire. Symptoms, dyspnea, and pulmonary function tests (spirometry, diffusing capacity for carbon monoxide, plethysmography, and 6-min walk test [6MWT]) were evaluated at baseline, and one and three months after having started the PR-PFD treatment. RESULTS: Seventy subjects with mild to moderate lung restriction were included. The most common AEs were diarrhea (23%), heartburn (23%), and headache (16%), for which no modifications in the drug study were needed. Two patients died within the first 30 days of enrolment, and three opted not to continue the study, events which were not associate with PR-PFD. Pulmonary function testing, 6MWT, dyspnea, symptoms, and CT scan significantly improved after three months of treatment with PR-PFD. CONCLUSION: In patients with PASC pulmonary fibrosis, three months' treatment with PR-PFD was safe and showed therapeutic efficacy. Still, it remains to be seen whether the pulmonary fibrotic process remains stable, becomes progressive or will improve.


Asunto(s)
COVID-19 , Fibrosis Pulmonar Idiopática , Neumonía , Humanos , COVID-19/complicaciones , Progresión de la Enfermedad , Disnea/tratamiento farmacológico , Disnea/etiología , Fibrosis Pulmonar Idiopática/complicaciones , Fibrosis Pulmonar Idiopática/tratamiento farmacológico , Fibrosis Pulmonar Idiopática/diagnóstico , Fenotipo , Neumonía/tratamiento farmacológico , Piridonas/efectos adversos
7.
Front Cardiovasc Med ; 10: 1190513, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37288254

RESUMEN

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Currently, cardiovascular disease risk algorithms play a role in primary prevention. However, this is complicated by a lack of powerfully predictive biomarkers that could be observed in individuals before the onset of overt symptoms. A key potential biomarker for heart disease is the vascular endothelial growth factor (VEGF-A), a molecule that plays a pivotal role in blood vessel formation. This molecule has a complex biological role in the cardiovascular system due to the processes it influences, and its production is impacted by various CVD risk factors. Research in different populations has shown single nucleotide polymorphisms (SNPs) may affect circulating VEGF-A plasma levels, with some variants associated with the development of CVDs, as well as CVD risk factors. This minireview aims to give an overview of the VEGF family, and of the SNPs reported to influence VEGF-A levels, cardiovascular disease, and other risk factors used in CVD risk assessments.

8.
Philos Trans R Soc Lond B Biol Sci ; 378(1867): 20210067, 2023 01 02.
Artículo en Inglés | MEDLINE | ID: mdl-36373912

RESUMEN

Reforestation is one of our most promising natural climate solutions, and one that addresses the looming biodiversity crisis. Tree planting can catalyse forest community reassembly in degraded landscapes where natural regeneration is slow, however, tree survival rates vary remarkably across projects. Building a trait-based framework for tree survival could streamline species selection in a way that generalizes across ecosystems, thereby increasing the effectiveness of the global restoration movement. We investigated how traits mediated seedling survival in a tropical dry forest restoration, and how traits were coordinated across plant structures. We examined growth and survival of 14 species for 2 years and measured six below-ground and 22 above-ground traits. Species-level survival ranged widely from 7.8% to 90.1%, and a model including growth rate, below-ground traits and their interaction explained more than 73% of this variation. A strong interaction between below-ground traits and growth rate indicated that selecting species with fast growth rates can promote establishment, but this effect was most apparent for species that invest in thick fine roots and deep root structures. Overall, results emphasize the prominent role of below-ground traits in determining early restoration outcomes, and highlight little above- and below-ground trait coordination, providing a path forward for tropical dry forest restoration efforts. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.


Asunto(s)
Ecosistema , Árboles , Bosques , Biodiversidad , Plantones , Clima Tropical
9.
J Minim Access Surg ; 19(2): 278-281, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36124470

RESUMEN

Introduction: Minimally invasive surgery has been established as the gold standard for the treatment of localised renal tumours. A retroperitoneal approach is a feasible option with advantages in posterior tumours and patients with previous abdominal surgeries. In this context, single-port retroperitoneoscopic partial nephrectomy (SPOR-PN) has not been widely explored and developed. We present this technique's description and our first results. Methods: We present a case series of nine patients undergoing SPOR-PN in a single institution. We used a multi-channel single-port access dispositive through a 35 mm incision below the 12th rib, a 30° two-dimensional laparoscope, curved graspers and needle drivers on the left hand and standard rigid material in the right hand. In all surgeries, we performed a complete renorrhaphy with the sliding-clip technique. The pain was evaluated through visual analogue scale (VAS) the day after surgery. Results: Patients' age ranged from 44 to 78 years. The median RENAL score was 5p, and the mean surgical time was 134 min. We performed an 'off-clamp' procedure on three patients. Among the patients who had renal artery clamped, the median ischaemia time was 18 min. The median in-hospital stay time was 48 h. Median VAS the day after surgery was 2. None of the anatomical pieces had positive borders. Only one complication was reported (Clavien IIIa). Conclusions: SPOR-PN is a feasible minimally invasive and nephron-sparing technique. The advantages of this procedure may not be only a better cosmetic appearance but also less post-operative pain. Further development and larger studies are needed.

10.
Artículo en Español | LILACS, BINACIS | ID: biblio-1523941

RESUMEN

El objetivo de esta presentación es dar a conocer el manejo de la miositis piógena del músculo obturador interno en un paciente pediátrico que fue tratado mediante un drenaje percutáneo guiado por ecografía. Se trata de un niño de 5 años de edad, con manifestaciones clínicas y valores de laboratorio de infección muscular profunda en el obturador interno. Se identificó específicamente con resonancia magnética, es un área de difícil acceso quirúrgico, por lo cual se realizó un tratamiento percutáneo guiado por ecografía que permitió drenar el contenido purulento de la zona afectada. La resonancia magnética hizo posible lograr un diagnóstico más acertado en los casos de infección piógena temprana y, a su vez, decidir la vía de abordaje más adecuada. En ocasiones, se puede optar por la guía ecográfica con la cual se evita el abordaje quirúrgico formal y así disminuyen las complicaciones de la herida y la mayor morbimortalidad. La adición de procedimientos percutáneos guiados por imágenes es una herramienta muy útil para tratar enfermedades infecciosas y una gran ayuda para el ortopedista. Nivel de Evidencia: V


The objective of this case report is to present the management of a case of pyogenic myositis of the obturator muscle in a pediatric patient using ultrasound-guided percutaneous drainage. The patient is a 5-year-old pediatric patient with clinical and laboratory manifestations of deep muscular infection at the obturator level, an area of difficult surgical access, for which the least invasive treatment possible was used to drain purulent content from the affected area. The use of magnetic resonance imaging studies allows for a more accurate diagnosis in cases of early pyogenic infection, as well as determining the most effective approach to treatment. In some cases, ultrasound guidance can be used to avoid a formal surgical approach, reducing wound complications and morbidity and mortality. The addition of image-guided percutaneous procedures is a very useful tool for the treatment of infectious diseases and a great help to the orthopedist. Level of Evidence: V


Asunto(s)
Preescolar , Drenaje , Ultrasonografía , Piomiositis , Cadera , Músculos
11.
Khirurgiia (Mosk) ; (12. Vyp. 2): 78-80, 2022.
Artículo en Ruso | MEDLINE | ID: mdl-36562677

RESUMEN

Meckel's diverticulum is the most common congenital defect of the gastrointestinal tract. It is most often silent or asymptomatic. However, acute abdominal signs of obstruction, inflammation, hemorrhage and perforation are possible in other cases. Different foreign bodies can cause perforation of Meckel's diverticulum. We present an 18-year-old male who presented to the emergency department with abdominal pain within 48 previous hours. After evaluation, acute appendicitis was diagnosed and he underwent laparoscopic appendectomy. Meckel's diverticulum perforated by a fish bone was intraoperatively discovered. Incidental appendectomy and segmental resection of the ileum were performed.


Asunto(s)
Cuerpos Extraños , Perforación Intestinal , Divertículo Ileal , Masculino , Animales , Divertículo Ileal/complicaciones , Divertículo Ileal/diagnóstico , Divertículo Ileal/cirugía , Perforación Intestinal/diagnóstico , Perforación Intestinal/etiología , Perforación Intestinal/cirugía , Cuerpos Extraños/complicaciones , Cuerpos Extraños/diagnóstico , Dolor Abdominal , Inflamación
12.
New Microbes New Infect ; 48: 101021, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-36060548

RESUMEN

Recurrent positivity in a patient with COVID-19 may be due to various reasons, not necessarily reinfection. There is concern about the occurrence frequency of reinfection. Five databases and a preprint/preprint repository were searched. All case reports, case series, and observational studies were included. Bias was assessed for each study with the Newcastle-Ottawa Scale tool and reported according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA-2020). After eligibility, 77 studies were included for qualitative synthesis (52 case reports, 21 case series, and four case-controls; 1131 patients included). Of these, 16 studies described a second contact with the SARS-CoV-2 positive case, five studies described healthcare profession-related infection, ten studies described that the source of reinfection was likely to be from the community, one study described travel-related infection, nine studies described vulnerability-related infection due to comorbidity. The mean number of days from discharge or negative test to reinfection ranged from 23.3 to 57.6 days across the different included studies. The risk of bias for all case report/series studies was moderate/high. For observational studies, the risk of bias was low. Reinfection of patients with COVID-19 occurs between the first and second month after the first infection, but beyond, and 90 days have been proposed as a point to begin to consider it. The main factor for reinfection is contact with COVID-19 positive cases.

13.
Appl Radiat Isot ; 186: 110269, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-35567932

RESUMEN

We present the radioanalytical strategies used for the determination of strontium radioisotopes in routine and emergency samples. While in routine monitoring, the main goal is to achieve limits of detection as low as possible. In emergency, priority is given to the rapid procurement of data about a contamination. The parameters accuracy, precision and detection limit of the radiochemical methods are shown. We present the results obtained over the past 22 years in proficiency tests and in the analysis of reference materials.


Asunto(s)
Monitoreo de Radiación , Radioisótopos de Estroncio , Monitoreo de Radiación/métodos , Conteo por Cintilación/métodos , Radioisótopos de Estroncio/análisis
14.
Sci Total Environ ; 838(Pt 1): 155910, 2022 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-35577081

RESUMEN

Digitisation is gaining importance with 3D workflow for architecture-specific annotation of built heritage. The objective is to use the Building Information Modeling (BIM) methodology in order to carry out a study of alternatives of impact on environmental sustainability associated with the potential allergenicity with green infrastructure on a new housing, located in Mérida (SW Spain). It is intended to simulate the meteorology (direction and speed of the wind) in the study city with the compass rose for 18 years (2003-2020) to assess the meteorological pattern associated with the wind on the studied housing. 3 green infrastructure garden alternatives (considering 5 ornamental species of cypress trees) were designed to evaluate the potential impact of allergenicity on the housing. AIROT index was applied to project the results on the frontage of the housing. This index was developed in the field of large areas of urban environments. The calculation was carried out in the most exact way possible in specific sections of the frontage of the housing and automatically with tools associated with the BIM environment (such as Autodesk Revit, Dynamo, Enscape, Wrplot and Bim One) to the discipline of Architecture (such as Autodesk Autocad and Autodesk Flow Design). The obtained results were applied to evaluate 3 scenario designs, trying to minimize the potential exposure to urban green infrastructure (focus on cypress trees) in this current project, and offering a health reference guide in future projects, from the design phase considering appropriate measures and proposing recommendations.


Asunto(s)
Contaminación del Aire , Alérgenos , Ciudades , Meteorología , Medición de Riesgo , Árboles
15.
Epidemiol Psychiatr Sci ; 31: e18, 2022 Mar 30.
Artículo en Inglés | MEDLINE | ID: mdl-35352674

RESUMEN

AIMS: To examine the association between benzodiazepine receptor agonist (BZRA) use and mortality in patients hospitalised for coronavirus disease 2019 (COVID-19). METHODS: A multicentre observational study was performed at Greater Paris University hospitals. The sample involved 14 381 patients hospitalised for COVID-19. A total of 686 (4.8%) inpatients received a BZRA at hospital admission at a mean daily diazepam-equivalent dose of 19.7 mg (standard deviation (s.d.) = 25.4). The study baseline was the date of admission, and the primary endpoint was death. We compared this endpoint between patients who received BZRAs and those who did not in time-to-event analyses adjusted for sociodemographic characteristics, medical comorbidities and other medications. The primary analysis was a Cox regression model with inverse probability weighting (IPW). RESULTS: Over a mean follow-up of 14.5 days (s.d. = 18.1), the primary endpoint occurred in 186 patients (27.1%) who received BZRAs and in 1134 patients (8.3%) who did not. There was a significant association between BZRA use and increased mortality both in the crude analysis (hazard ratio (HR) = 3.20; 95% confidence interval (CI) = 2.74-3.74; p < 0.01) and in the IPW analysis (HR = 1.61; 95% CI = 1.31-1.98, p < 0.01), with a significant dose-dependent relationship (HR = 1.55; 95% CI = 1.08-2.22; p = 0.02). This association remained significant in sensitivity analyses. Exploratory analyses indicate that most BZRAs may be associated with an increased mortality among patients hospitalised for COVID-19, except for diazepam, which may be associated with a reduced mortality compared with any other BZRA treatment. CONCLUSIONS: BZRA use may be associated with an increased mortality among patients hospitalised for COVID-19, suggesting the potential benefit of decreasing dose or tapering off gradually these medications when possible.


Asunto(s)
COVID-19 , Antagonistas de Receptores de GABA-A/efectos adversos , COVID-19/mortalidad , Hospitalización , Humanos , Modelos de Riesgos Proporcionales
16.
R Soc Open Sci ; 9(1): 201154, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-35242340

RESUMEN

Protected areas (PAs) constitute one of the main tools for global landscape conservation. Recently, payments for environmental services (PES) have attracted interest from national and regional governments and are becoming one of the leading conservation policy instruments in tropical countries. However, the degree to which areas designated for PES overlap with areas that are critical for maintaining species' landscape connectivity is rarely evaluated. We estimated habitat distributions and connectivity for 16 of the 22 mammalian carnivores occurring in the Caribbean region of Colombia, and identified the overlap between existing PAs and areas identified as being important for connectivity for these species. We also evaluated the potential impact of creation of new PAs versus new PES areas on conserving connectivity for carnivores. Our results show that PAs cover only a minor percentage of the total area that is important for maintaining connectivity ( x = 26.8 % ± 20.2 s . d . ). On the other hand, PES, if implemented extensively, could contribute substantially to mammalian carnivores' connectivity ( x = 45.4 % ± 12.8 s . d . ). However, in a more realistic scenario with limited conservation investment in which fewer areas are set aside, a strategy based on implementing new PAs seems superior to PES. We argue that prioritizing designation of new PAs will be the most efficient means through which to maintain connectivity.

17.
J Environ Radioact ; 242: 106795, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34923320

RESUMEN

We present plutonium (Pu) and uranium (U) isotopic fingerprints (or signatures) in environmental samples collected at Bikar Atoll. Bikar is the second -most northern atoll of the Republic of the Marshall Islands, and therefore an important reference point to evaluate the extension of the regional fallout from the Pacific Proving Grounds (PPG) in Bikini and Enewetak Atolls. Previous studies have shown that regional fallout from atmospheric nuclear weapon testing (NWT) in Bikini and Enewetak has resulted in elevated levels of fallout radionuclides in this atoll. In order to optimally interpret the isotopic fingerprints, we compare our results with data obtained in eleven certified reference materials, representing different contamination sources. As well as 238Pu, 239Pu, 240Pu, 241Pu, 238U and 235U, this study also encompasses less commonly reported radionuclides such as 242Pu, 244Pu and 236U. We show the importance of combining numerous fingerprints for improved assessment of the source of a nuclear contamination. In samples from Bikar, Pu and U isotope ratios were found to vary within narrow ranges. Pu and U fingerprints suggest that regional fallout from the Castle Bravo test in March 1954 was the main source of the contamination. This was further confirmed by two different age dating approaches that estimated 1954 as the year of the contamination. We demonstrate that use of an exponential function to approximate the yield of heavy radionuclides in thermonuclear explosions with increasing mass is a valid approach for estimating the age of a contamination. We show that, if sufficient radionuclide activity concentration measurement results with low uncertainties are available, this method is robust.


Asunto(s)
Plutonio , Monitoreo de Radiación , Uranio , Micronesia
18.
Sci Total Environ ; 812: 152312, 2022 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-34953833

RESUMEN

The goal of this study is to estimate the potential risk of exposure to urban green infrastructure by calculating and improving of AIROT index, adding meteorological factors as wind direction and updating the index to be more accurate for smaller urban green areas. To achieve this objective, BIM methodology has been applied by creating a 3D BIM model from the reality capture of a street with LiDAR. The BIM model contains the parametric data needed to apply AIROT index and it allows to map results in a graphic environmental sustainability study. The importance of location of green infrastructure is one of main conclusions obtained in order to minimize aerobiological risks in future new buildings or even in maintenance tasks of urban green infrastructure. A valuable result obtained from the developed methodology are walk simulations in the 3D model with the aim to identify high risk of potential exposure of urban green infrastructure with allergenic interest for allergic patients in order to supply health itineraries of pedestrians in a proposal of Smart City.


Asunto(s)
Peatones , Caminata , Alérgenos , Ciudades , Humanos , Viento
19.
Psicol. esc. educ ; 26: e231651, 2022. graf
Artículo en Español | LILACS-Express | LILACS, Index Psicología - Revistas | ID: biblio-1422427

RESUMEN

RESUMEN El estudio analizó el vínculo entre la didáctica de maestros y las habilidades cognoscitivas de atención, memoria, velocidad y fluidez verbal en estudiantes de primeros grados de un colegio público en Cúcuta-Colombia. Se propuso un diseño exploratorio concurrente con análisis cualitativo y recolección de datos de fuente mixta, con muestreo intencional de 22 estudiantes y 4 maestras. Se evaluaron habilidades cognoscitivas mediante pruebas neuropsicológicas estandarizadas para Colombia y la didáctica fue explorada mediante entrevista semiestructurada siguiendo categorías de enseñanza, aprendizaje y técnicas. Las habilidades cognoscitivas se analizaron mediante estadística descriptiva y las entrevistas por análisis de triangulación categorial, concluyendo en los niños sobresaliente memoria-velocidad y disminuida atención y fluidez verbal, hallazgos sobresalientes vinculados a didácticas basadas en uso de fichas de aprendizaje, repetición, mecanización, mientras que los resultados inferiores se asociaron al uso de video y pasatiempos.


RESUMO O estudo analisou a relação entre a didática de professores e as habilidades cognoscitivas de atenção, memória, velocidade e fluidez verbal em estudantes de primeiros anos de uma escola pública em Cúcuta - Colômbia. Utilizou-se um roteiro exploratório junto com análises qualitativa e levantamento de dados de fonte mista, com amostra intencional de 22 estudantes e 4 professores. Avaliaram-se habilidades cognoscitivas mediante testes neuropsicológicos normatizados para Colômbia e a didática foi explorada mediante entrevista semiestruturada seguindo categorias de ensino, aprendizagem e técnicas. As habilidades cognoscitivas foram analisadas mediante estatística descritiva e as entrevistas por análise de triangulação categorial, concluindo-se nas crianças importantes memória-velocidade e diminuída atenção e fluidez verbal, achados marcantes vinculados a didáticas baseadas no uso de fichas de aprendizagem, repetição, mecanização, enquanto os resultados inferiores foram associados ao uso de vídeo e passatempos.


ABSTRACT The study analyzed the relationship between teacher didactics and cognitive skills of attention, memory, speed and verbal fluidity in first-year students of a public school in Cúcuta-Colombia. An exploratory script was used, together with qualitative analysis and mixed-source data collection, with an intentional sample of 22 students and 4 teachers. Cognitive abilities were evaluated through neuropsychological tests standardized for Colombia, and didactics were explored through semi-structured interviews following categories of teaching, learning and techniques. Cognitive skills were analyzed using descriptive statistics and interviews by categorical triangulation analysis, concluding in important children memory-speed and reduced attention and verbal fluidity, remarkable findings linked to didactics based on the use of learning sheets, repetition, mechanization, while lower results were associated with the use of video and hobbies.

20.
J Environ Radioact ; 232: 106584, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33744558

RESUMEN

The Aare-Rhine river system with its four nuclear power plants on the banks of these rivers and with its intermediate lakes and reservoirs provide the unique chance to analyze the input of radioactivity into the system thereby furnishing information on the sources, to analyze the transport within the sediment and along the rivers, and to refine unsupported 210Pb dating validated by known discharge maxima. At three locations (Lake Biel, Klingnau Reservoir, old branch of the Rhine) in the Aare and Rhine rivers system downstream of the older nuclear power plants (NPPs) Mühleberg and Beznau, the vertical distributions of 137Cs, 210Pb, 214Pb, 214Bi, 40K, 7Be, 239Pu, 240Pu, 241Am, and 237Np in sediment cores were determined. Depth-age relations using the excess 210 Pb were established with the raw and with the piecewise Constant Rate Supply (CRS) models. A comparison of the piecewise CRS method with the imprints of known discharges showed differences of up to two years. Besides typical 137Cs signals (about 100 Bq∙kg-1) from the atmospheric nuclear weapons testing (NWT) and the Chernobyl fallouts, imprints of known 137Cs discharges (10-70 Bq∙kg-1) from the NPPs were found in the sediments. The 237Np distributions (6-10 Bq∙kg-1) essentially follow the 137Cs NWT distributions. In the sediment downstream the NPP Mühleberg (Lake Biel) a239Pu distribution (<3 Bq∙kg-1) was found, which was solely due to the NWT fallout. Downstream the NPP Beznau (Klingnau Reservoir and an old branch of the Rhine), besides the NWT distribution, also imprints of 239Pu discharges (up to 7 Bq∙kg-1) were found within the time interval 1963 to 1986.240Pu/239Pu ratios revealed that the burn-up times of the nuclear fuel in the NPP (235U enrichment of 3.5%), from which the discharges stem, should be about 1 year or less. A comparison between the calculated and the measured 137Cs/239Pu ratio revealed no large discrepancies for the Lake Biel and Rhine positions, but in the Klingnau distribution, the calculated 137Cs/239Pu ratio is one order of magnitude larger than the measured one. The reason could be either a natural uranium research reactor as the source, or strong, short-range 239Pu precipitation after the discharge from the Beznau NPP. The largest 239Pu peak in the Rhine sediment (1968/70) corresponds to no major peak in the Klingnau sediment. For the NPP Mühleberg discharge of 1982 the ratio of the 137Cs deposition in sediments from Lake Biel, Klingnau Reservoir and the Rhine river is about 1 : 0.5 : 2.9. For the 1977/78 239Pu deposition the ratio is 1 : 0.02, for the Klingnau Reservoir and the Rhine sediments, respectively. These numbers indicate a long-range transport of Cs and a rather short-range transport of Pu.


Asunto(s)
Monitoreo de Radiación , Contaminantes Radiactivos del Agua , Sedimentos Geológicos , Lagos , Ríos , Contaminantes Radiactivos del Agua/análisis
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...