Influence of Single and Double Membrane Roofs on Thermal Behaviour of Enclosed Space

Even though membrane structures have been increasingly used in the world, their energy efficiency is very unfavourable due to poor thermal properties. This causes relatively high consumption of heating energy in the winter, as well energy consumed for the operation of air-conditioning during the summer, that is, under circumstances which require thermal comfort. Since thermal comfort depends on the air temperature and temperature of the interior surfaces of the envelope, this paper presents a study of the measurement and comparison of temperatures of single and double membrane structures in the summer period. Data collection was accomplished by measuring two adjacent structures, one covered with single and the other covered by a double membrane. Verification of the measured data was performed by comparing it with the official measured temperatures in the same period. The air temperatures were measured in all the separate air compartments and particular surfaces of each membrane. By analysing the measured data and their classification based on daylight and night-time periods, certain conclusions were drawn about the influence of an additional layer of membrane on the temperature of the air inside a covered structure

The Thermal Behaviour of a Cylindrical Air Layer Enclosed between Double Fabric Roof Membranes

Objects covered by fabric roof membranes are specific in terms of energy consumption, primarily because of the negligible thickness of the material and its good thermal conduction properties. One of the ways of improving the energy efficiency of these objects is the implementation of a double fabric roof membrane structure with an enclosed non ventilated air layer. This paper analyzes the thermal-insulation behaviour of the air layer enclosed between tensile fabric roof membranes which are used for structural purposes. The compilation of the necessary data was carried out by measuring a real object covered by a double fabric roof membrane, semi-cylindrical in shape. The surface temperatures of each membrane were measured, as were the outside and inside air temperature and the air temperature between the membranes during the summer months. In addition, the solar irradiance during the same period was also measured. The analysis of the measured data took into consideration all the present forms of energy transmittance (convection, conduction and radiation), as well as the shape of the air layer and the thermal-physical specific features of border surfaces. The results of the study indicate that thermal behaviour of a closed semi-cylindrical air layer depends on the real outer conditions in the summer months. A methodological approach to the thermal modelling of these structures has accordingly been proposed

Slower EEG alpha generation, synchronization and “flow”—possible biomarkers of cognitive impairment and neuropathology of minor stroke

Background. We investigated EEG rhythms, particularly alpha activity, and their relationship to post-stroke neuropathology and cognitive functions in the subacute and chronic stages of minor strokes. Methods. We included 10 patients with right middle cerebral artery (MCA) ischemic strokes a nd 11 healthy controls. All the assessments of stroke patients were done both in the subacute and chronic stages. Neurological impairment was measured using the National Institute of Health Stroke Scale (NIHSS), whereas cognitive functions were assessed using the Montreal Cognitive Assessment (MoCA) and MoCA memory index (MoCA-MIS). The EEG was recorded using a 19 channel EEG system with standard EEG electrode placement. In particular, we analyzed the EEGs derived from the four lateral frontal (F3, F7, F4, F8), and corresponding lateral posterior (P3, P4, T5, T6) electrodes. Quantitative EEG analysis included: the group FFT spectra, the weighted average of alpha frequency (α AVG), the group probability density distributions of all conventional EEG frequency band relative amplitudes (EEG microstructure), the inter- and intra-hemispheric coherences, and the topographic distribution of alpha carrier frequency phase potentials (PPs). Statistical analysis was done using a Kruskal-Wallis ANOVA with a post-hoc Mann-WhitneyU two-tailed test, and Spearman's correlation. Results. We demonstrated transient cognitive impairment alongside a slower alpha fre- quency (αAVG) in the subacute right MCA stroke patients vs. the controls. This slower alpha frequency showed no amplitude change, but was highly synchronized intra- hemispherically, overlying the ipsi-lesional hemisphere, and inter-hemispherically, overlying the frontal cortex. In addition, the disturbances in EEG alpha activity in subacute stroke patients were expressed as a decrease in alpha PPs over the frontal cortex and an altered "alpha flow", indicating the sustained augmentation of inter- hemispheric interactions. Although the stroke induced slower alpha was a transient phenomenon, the increased alpha intra-hemispheric synchronization, overlying the ipsi-lesional hemisphere, the increased alpha F3-F4 inter-hemispheric synchronization, the delayed alpha waves, and the newly established inter-hemispheric "alpha flow" within the frontal cortex, remained as a permanent consequence of the minor stroke. This newly established frontal inter-hemispheric "alpha flow" represented a permanent consequence of the ``hidden" stroke neuropathology, despite the fact that cognitive impairment has been returned to the control values. All the detected permanent changes at the EEG level with no cognitive impairment after a minor stroke could be a way for the brain to compensate for the lesion and restore the lost function. Discussion. Our study indicates slower EEG alpha generation, synchronization and ``flow" as potential biomarkers of cognitive impairment onset and/or compensatory post-stroke re-organizational processes.PeerJ (2017), 5(9): e383

The influence of diversity on the measurement of functional impairment : An international validation of the Amsterdam IADL questionnaire in 8 countries

Peer reviewe

Degree of cognitive impairment in patients with carotid stenosis in relation to cerebral ischemic lesions

Background/Aim. The presence of carotid stenosis is a risk factor for cognitive impairment. The aim of our study was to evaluate the degree of cognitive impairment in patients with asymptomatic and symptomatic carotid stenosis and correlate it with the presence, location, and extent of cerebral ischemic lesions. Material and methods. A prospective analysis of 180 patients aged 50-70years, divided into three groups (asymptomatic, symptomatic carotid stenosis and controls), was made. We assessed demographic characteristics, vascular risk factors, ultrasound examination of the carotid arteries, computerized tomography (CT), magnetic resonance imaging (MRI) of the brain, and neuropsychological testing. Results. The brain CT findings at admission showed ischemic lesions in the left hemisphere in 13.3% patients of the asymptomatic and 41% in the symptomatic group. In the right hemisphere, lesions were registered in 10% of the asymptomatic and 46,7% of the symptomatic patients. The difference between groups was statistically significant. The lesion volumes measured on CT and MRI scans were significantly different (p < 0.001) between groups with asymptomatic and symptomatic carotid stenosis. The degree of cognitive impairment measured by the ACE-R test was significantly different between groups (p<0.05) with the most severe deficit in the symptomatic group. Conclusion. Our study has shown that cognitive impairment was more severe in patients with symptomatic carotid stenosis, compared to the patients with asymptomatic carotid stenosis

Impact of Sensorineural Hearing Loss during the Pandemic of COVID-19 on the Appearance of Depressive Symptoms, Anxiety and Stress

Background. The incidence of hearing loss is constantly increasing and according to the World Health Organization, by 2050, 900 million people will suffer from hearing loss. The main Objective of the study was to determine the differences between the severity of the symptoms of stress, anxiety and depression in participants with varying degrees of sensorineural hearing loss during the COVID-19 pandemic. An additional aim was to examine the extent and manner in which protective face masks impact the communication of people with hearing loss. Matrials and Methods: A cross-sectional study was conducted, which included 160 patients (81 men and 79 women) with bilateral sensorineural hearing loss. The patients’ age range was 50 to 80 years. Depending on the degree of hearing loss or pure-tone threshold, the participants were divided into four groups: mild hearing loss, moderate hearing loss, severe hearing loss and profound hearing loss. The research used the Depression, Anxiety and Stress Scale (DASS-21) and a questionnaire in which the participants reported whether surgical face masks (medical three-layer masks) worn by speakers makes communication difficult, to what extent and in what way. Results: The average age of the patients was 67.97 ± 8.16. A significant correlation was found between the degree of hearing loss and communication difficulties caused by the use of protective face masks (p p p = 0.024), anxiety (p = 0.026) and depression (p = 0.016). Conclusions: We have determined that face masks used during the COVID-19 pandemic significantly hamper communication among the study groups (p = 0.007) and there is a significant correlation between the degree of sensorineural hearing loss and the presence of symptoms in all three DASS-21 subscales, meaning that the symptoms of stress, anxiety and depression were more intense in severe and profound hearing loss