Turnover of 137Cs in ‘soil–tree’ system: An experience of measuring the isotope flows in a Siberian conifer forest

Publication date: December 2016
Source:Journal of Environmental Radioactivity, Volume 165
Author(s): Vladimir L. Gavrikov, Ruslan A. Sharafutdinov, Aleksandr R. Mitev
Little attention has been paid to the uptake of ¹³⁷Cs in natural forests under low levels of the isotope fallout when no immediate ecological danger presents. Here we present the extended assessments of the soil-to-plant and canopy-to-litter flows of ¹³⁷Cs recently evaluated in a native Siberian forested area. The area undergoes a typical after-fire long term succession, with light-conifer upper story being followed by undergrowth of Siberian fir and other dark-conifer species. The one-year-old needles of Siberian fir were found to accumulate the largest concentration of the isotope, 4.10 Bq/kg oven-dry weight during the first growth season, as compared with older needles that accumulated 4.67 Bq/kg oven-dry weight in 2–3 years of growth. Based on these data an approach was developed that, hypothetically, can allow one to estimate the ¹³⁷Cs activity concentration in soil solutions. Direct activity measurements in the soil solutions were not possible. The isotope activity in soil solutions was estimated to be 0.0061–0.0105 Bq/L. Based on the original data from the litter fall the annual flow of the isotope from the upper canopy to on-ground litter was found to be 0.42–0.84 Bq/m². The amount of ¹³⁷Cs that returns yearly back from canopy with falling litter was estimated to be 0.012–0.015% of the total soil isotope content. A combination of the estimations obtained in our study with the values of global ¹³⁷Cs fallout allowed us to assess the ages (the time of formation) of horizons of the soils in the area.



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Relationships between indoor radon concentrations, thermal retrofit and dwelling characteristics

Publication date: December 2016
Source:Journal of Environmental Radioactivity, Volume 165
Author(s): Bernard Collignan, Eline Le Ponner, Corinne Mandin
A monitoring campaign was conducted on a sample of more than 3400 dwellings in Brittany, France from 2011 to 2014. The measurements were collected using one passive dosimeter per dwelling over two months during the heating season, according to the NF ISO 11665–8 (2013) standard. Moreover, building characteristics such as the period of construction, construction material, type of foundation, and thermal retrofit were determined using a questionnaire. The final data set consisted of 3233 houses with the measurement results and the questionnaire answers. Multivariate linear regression models were applied to explore the relationships between the indoor radon concentrations and building characteristics, particularly the thermal retrofit.The geometric mean of the indoor radon concentration was 155 Bq m⁻³ (with a geometric standard deviation of 3). The houses that had undergone a thermal retrofit had a higher average radon concentration than those that had not, which may have been due to a decrease in air permeability of the building envelope following rehabilitation work that did not systematically include proper management of the ventilation. Other building characteristics, primarily the building material and the foundation type, were associated with the indoor radon concentration. The indoor radon concentrations were higher in older houses built with granite or other stone, with a slab-on-grade foundation and without any ventilation system.



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Racecadotril May Reduce Diarrhoea In Microvillous Inclusion Disease.

No abstract available

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Propofol Pharmacodynamics and Bispectral Index During Key Moments of Awake Craniotomy.

Background: During awake craniotomy, the patient's language centers are identified by neurological testing requiring a fully awake and cooperative patient. Hence, anesthesia aims for an unconscious patient at the beginning and end of surgery but an awake and responsive patient in between. We investigated the plasma (Cplasma) and effect-site (Ceffect-site) propofol concentration as well as the related Bispectral Index (BIS) required for intraoperative return of consciousness and begin of neurological testing. Materials and Methods: In 13 patients, arterial Cplasma were measured by high-pressure liquid chromatography and Ceffect-site was estimated based on the Marsh and Schnider pharmacokinetic/dynamic (pk/pd) models. The BIS, Cplasma and Ceffect-site were compared during the intraoperative awakening period at designated time points such as return of consciousness and start of the Boston Naming Test (neurological test). Results: Return of consciousness occurred at a BIS of 77+/-7 (mean+/-SD) and a measured Cplasma of 1.2+/-0.4 [mu]g/mL. The Marsh model predicted a significantly (P

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Kilohertz and Low-Frequency Electrical Stimulation With the Same Pulse Duration Have Similar Efficiency for Inducing Isometric Knee Extension Torque and Discomfort.

Objective: To test the hypotheses that, as compared with pulsed current with the same pulse duration, kilohertz frequency alternating current would not differ in terms of evoked-torque production and perceived discomfort, and as a result, it would show the same current efficiency. Design: A repeated-measures design with 4 stimuli presented in random order was used to test 25 women: (1) 500-microsecond pulse duration, (2) 250-microsecond pulse duration, (3) 500-microsecond pulse duration and low carrier frequency (1 kHz), (4) 250-microsecond pulse duration and high carrier frequency (4 kHz). Isometric peak torque of quadriceps muscle was measured using an isokinetic dynamometer. Discomfort was measured using a visual analog scale. Results: Currents with long pulse durations induced approximately 21% higher evoked torque than short pulse durations. In addition, currents with 500 microseconds delivered greater amounts of charge than stimulation patterns using 250-microsecond pulse durations (P

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Perceived Exertion Is Lower When Using a Functional Electrical Stimulation Neuroprosthesis Compared With an Ankle-Foot Orthosis in Persons With Multiple Sclerosis: A Preliminary Study.

Objective: This study investigates the direct comparison of energy cost, efficiency, and effort between an ankle-foot orthosis (AFO) and a functional electrical stimulation (FES) device for foot drop in ambulatory patients with multiple sclerosis. Design: Twenty adults (32-74 years old; 55% female) with a diagnosis of multiple sclerosis resulting in foot drop participated in a crossover, counterbalanced preliminary study. Each participant was tested on different days, with each session consisting of a separate walk trial per prosthetic device. Heart rate, oxygen consumption, speed, distance, and self-reported exertion were measured independently for each device walk trial. Repeated-measures analysis of variance with device and visit number as within-participants independent variables were run for the primary outcome variables of perceived exertion, energy, and metabolic efficiency. Results: A significant main effect of device was found for perceived exertion (P = 0.01), with participants reporting decreased exertion levels (Borg Scale) when using the FES compared with the AFO (mean difference, 1.63; 95% confidence interval, 0.49-2.76). Energy and efficiency did not significantly differ by device. Conclusion: Results suggest that further investigation of the potential advantages of FES devices over traditional AFO is warranted. To Claim CME Credits: Complete the self-assessment activity and evaluation online at http://ift.tt/1l80W45 CME Objectives: Upon completion of this article, the reader should be able to: (1) describe potential differences between an AFO and FES for treatment of foot drop in patients with multiple sclerosis, (2) understand the mechanisms and prevalence of foot drop in patients with multiple sclerosis, and (3) recognize the potential benefit of improved perceived exertion found when using FES for the treatment of foot drop in patients with multiple sclerosis. Level: Advanced Accreditation: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The Association of Academic Physiatrists designates this activity for amaximum of 1.5 AMA PRA Category 1 Credit(s)(TM). Physicians should only claim credit commensurate with the extent of their participation in the activity. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.

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Dissociating parafoveal preview benefit and parafovea-on-fovea effects during reading: A combined eye tracking and EEG study

Abstract

During reading, the parafoveal processing of an upcoming word n+1 can influence word recognition in two ways: It can affect fixation behavior during the preceding fixation on word n (parafovea-on-fovea effect, POF), and it can facilitate subsequent foveal processing once word n+1 is fixated (preview benefit). While preview benefits are established, evidence for POF effects is mixed. Recently, it has been suggested that POF effects exist, but have a delayed impact on saccade planning and thus coincide with preview benefits measured on word n+1. We combined eye movement and EEG recordings to investigate and separate neural correlates of POF and preview benefit effects. Participants read lists of nouns either in a boundary paradigm or the RSVP-with-flankers paradigm, while we recorded fixation- or event-related potentials (FRPs/ERPs), respectively. The validity and lexical frequency of the word shown as preview for the upcoming word n+1 were orthogonally manipulated. Analyses focused on the first fixation on word n+1. Preview validity (correct vs. incorrect preview) strongly modulated fixation times and electrophysiological N1 amplitudes, replicating previous findings. Importantly, gaze durations and FRPs measured on word n+1 were also affected by the frequency of the word shown as preview, with low-frequency previews eliciting a sustained, N400-like centroparietal negativity. Results support the idea that POF effects exist but affect word recognition with a delay. Lastly, once word n+1 was fixated, its frequency also modulated N1 amplitudes in ERPs and FRPs. Taken together, we separated immediate and delayed effects of parafoveal processing on brain correlates of word recognition.

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