Quantitative Assessment of the Kinetics of Damage Accumulation in the Polymer Matrix Structure Under Full-Scale Climatic Factors and Tensile Loads

Постановка задачи. Изучено изменение упруго-прочностных показателей и кинетики накопления повреждений в эпоксидных полимерах под действием растягивающих нагрузок в контрольном состоянии и после натурного климатического воздействия в течение одного календарного года. Расчет кинетики накопления повреждений осуществлялся на основе авторской методики, основанной на использовании методов фрактального анализа кривых деформирования образцов полимерных материалов при растяжении. Результаты. Предложен удельный показатель θ, позволяющий количественно оценивать суммарное число повреждений на единицу прочности, накопление которого приводит к разрушению полимеров. Получены аппроксимирующие зависимости, описывающие взаимосвязь между удельным показателем θ и пределом прочности эпоксидных полимеров при растяжении. Выводы. Установлено, что наибольшей стабильностью свойств под действием натурного климатического воздействия обладает полимер на основе эпоксидной смолы «Этал-247». Statement of the problem. In the current study we look at the change in the elastic-strength performance and kinetics of damage accumulation in epoxy polymers under tensile loads in the control state and after full-scale climatic exposure during one calendar year were studied. Damage accumulation kinetics was calculated based on the author's method using methods of fractal analysis of deformation curves for polymer materials samples under tension. Results. We proposed specific index θ to quantify the total number of damages per unit of strength where its accumulation leads to the destruction of polymers. The dependences have been obtained that describe the relationship between specific index θ and tensile strength of epoxy polymers. Consclusion. The study has shown that the Etal-247 epoxy resin-based polymer cured with Etal-1440 amine hardener has the most stable properties under the full-scale climatic exposure.

What Do Introduction to Psychology Textbooks Have to Say About Older Adults?

Introduction to Psychology is one of the most popular undergraduate courses, an entry course for psychology majors and also popular with students from other disciplines. Consequently, the content in introductory psychology textbooks has the potential to influence undergraduates’ knowledge, attitudes, and interests, including those related to aging. The purpose of this study was to analyze aging-related content in introductory psychology textbooks to understand the topics to which students are exposed in this important course. We analyzed the indices of 21 best-selling Introduction to Psychology textbooks for both advanced and intermediate audiences, published between 2018 and 2020. We extracted and aggregated 275 unique, aging-specific index terms from the textbooks and analyzed their relative frequency. We identified 61 superordinate index terms corresponding to general terms (e.g., “aging,” “death”). The indices also included 214 unique subordinate terms that were more specific (e.g., “aging, and cognition”). Across textbooks, the most frequent topics reflected negative consequences of aging (e.g., “Alzheimer disease” = appeared in 100% of textbooks, “death” in 52%). In contrast, positive aspects of aging appeared less often (e.g., “generativity” in 47%, “longevity” in 10%). Terms describing career opportunities were rare (e.g., “gerontology” in 5%, “geropsychology” in 5%), as were modern theories (e.g., “socioemotional selectivity theory” in 28%). Advocacy for comprehensive and balanced representation of aging in introductory psychology textbooks is critical for educating students and promoting interest in the field.

QUANTITATIVE ASSESSMENT OF THE KINETICS OF DAMAGE ACCUMULATION IN THE POLYMER MATRIX STRUCTURE UNDER FULL-SCALE CLIMATIC FACTORS AND TENSILE LOADS

Statement of the problem. In the current study we look at the change in the elastic-strength performance and kinetics of damage accumulation in epoxy polymers under tensile loads in the control state and after full-scale climatic exposure during one calendar year were studied. Damage accumulation kinetics was calculated based on the author's method using methods of fractal analysis of deformation curves for polymer materials samples under tension.Results. We proposed specific index θ to quantify the total number of damages per unit of strength,where its accumulation leads to the destruction of polymers. We obtained approximating dependences that describe the relationship between specific index θ and tensile strength of epoxy polymers.Consclusion. The study has shown that the Etal-247 epoxy resin-based polymer cured withEtal-1440 amine hardener has the most stable properties under the full-scale climatic exposure.

Not too close! impact of roommate status on MRSA and VRE colonization and contamination in Nursing Homes

Multiple room occupancy is common in Nursing Homes (NHs), and its role in transmission of antibiotic-resistant pathogens is unclear. We investigated prevalence of patient colonization and environmental contamination with vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) in NH roommates, compared it with expected prevalence, and determined specific body and environmental sites that may act as sources of roommate colonization. Roommate contamination was associated with index patient’s colonization (relative risk (RR): 2.57 (95% CI 1.04–6.37)) for MRSA, and index patient’s immediate environment contamination for VRE (RR: 3.60 (95% CI 1.59–8.12)). When specific index patient sites associated with roommate colonization were investigated, the side table (Fisher’s p = 0.029 and 0.047 for VRE and MRSA, respectively) and the nurse call button (p = 0.001 and 0.052) stood out, together with patient hands in the case of VRE (p = 0.026). Future studies should be carried out to establish whether these sites should be a specific target of infection prevention campaigns in NHs with multiple occupancy rooms.

Diet of the rasptail skate, Rostroraja velezi (Rajiformes: Rajidae), off Piura, Peru

Batoids are among the least studied group of vertebrates and one of the most vulnerable to fishing. The rasptail skate, Rostroraja velezi, is a bycatch species in northern Peru for which there are no studies on its diet. This research aims to document the diet of R. velezi on the northern Peruvian coast and to determine if there are sex-based differences in the diet. A total of 74 R. velezi stomachs were collected, 59 of which had stomach contents. The cumulative prey curve showed reliability in the number of samples collected. According to the prey-specific index of relative importance, diet was dominated by Acanthephyra sp. (31%), other unidentified Caridea (15%), and unidentified teleosts (17%). A low significant difference in diet between sexes was found (R = 0.21, P < 0.01). The trophic position of R. velezi was 3.9 ± 0.7. This species displays bentopelagic feeding behavior and it is a secondary predator in northern Peru.

Concurrent feature-specific reactivation within the hippocampus and neocortex facilitates episodic memory retrieval

The hippocampus is a key brain region for the storage and retrieval of episodic memories, but how it performs this function is unresolved. According to the hippocampal indexing theory, the hippocampus stores an event-specific index of the pattern of neocortical activity that occurred during perception. During retrieval, reactivation of the index by a partial cue facilitates the reactivation of the associated neocortical pattern. Therefore, event-specific retrieval requires joint reactivation of the hippocampal index and the associated neocortical networks. To test this theory, we examine the relation between performance on a recognition memory task requiring retrieval of image-specific visual details and feature-specific reactivation within the hippocampus and neocortex. We show that trial-by-trial recognition accuracy correlates with neural reactivation of low-level features (e.g. luminosity and edges) within the posterior hippocampus and early visual cortex for participants with high recognition lure accuracy. As predicted, the two regions interact, such that recognition accuracy correlates with hippocampal reactivation only when reactivation co-occurs within the early visual cortex (and vice-versa). In addition to supporting the hippocampal indexing theory, our findings show large individual differences in the features underlying visual memory and suggest that the anterior and posterior hippocampus represents gist-like and detailed features, respectively.

Application of Reflectance Ratios on High-Resolution Satellite Imagery to Remotely Identify Eucalypt Vegetation

The scale and accessibility of passive global surveillance have rapidly increased over time. This provides an opportunity to calibrate the performance of models, algorithms, and reflectance ratios between remote-sensing devices. Here, we test the sensitivity and specificity of the Eucalypt chlorophyll-a reflectance ratio (ECARR) and Eucalypt chlorophyll-b reflectance ratio (ECBRR) to remotely identify eucalypt vegetation in Queensland, Australia. We compare the reflectance ratio values from Sentinel-2 and Planet imagery across four sites of known vegetation composition. All imagery was transformed to reflectance values, and Planet imagery was additionally scaled to harmonize across Planet scenes. ECARR can identify eucalypt vegetation remotely with high sensitivity but shows low specificity and is impacted by the density of the vegetation. ECBRR reflectance ratios show similar sensitivity and specificity when identifying eucalypt vegetation but with values an order of magnitude smaller than ECARR. We find that ECARR was better at identifying eucalypt vegetation in the Sentinel-2 imagery than Planet imagery. ECARR can serve as a general chlorophyll indicator but is not a specific index to identify Eucalyptus vegetation with certainty.

Application of Reflectance Ratios on High-Resolution Satellite Imagery to Remotely Identify Eucalypt Vegetation

The scale and accessibility of passive global surveillance have rapidly increased over time. This provides an opportunity to calibrate the performance of models, algorithms, and reflectance ratios between remote sensing devices. Here we test the sensitivity and specificity of Eucalypt chlorophyll-a reflectance ratio (ECARR) and Eucalypt chlorophyll-b reflectance ratio (ECBRR) to remotely identify eucalypt vegetation in Queensland, Australia. We compare reflectance ratio values from Sentinel-2 and Planet imagery across four sites of known vegetation composition. All imagery was transformed to reflectance values and Planet imagery was additionally scaled to harmonize across Planet Scenes. ECARR can identify eucalypt vegetation remotely with high sensitivity, but shows low specificity and is impacted by the density of the vegetation. ECBRR reflectance ratios show similar sensitivity and specificity when identifying eucalypt vegetation but with values an order of magnitude smaller than ECARR. We find that ECARR was better at identifying eucalypt vegetation in the Sentinel-2 imagery than Planet imagery. ECARR can serve as a general chlorophyll indicator but is not a specific index to identify Eucalyptus vegetation with certainty.

Montreal Cognitive Assessment (MoCA) Performance and Domain-Specific Index Scores in Amnestic Versus Aphasic Dementia

ABSTRACTObjective:The Montreal Cognitive Assessment (MoCA) is a popular and simple-to-administer screening instrument to detect cognitive impairment. The MoCA generates a total score and six domain-specific index scores: (1) Memory, (2) Executive Functioning, (3) Attention, (4) Language, (5) Visuospatial, and (6) Orientation. It is unclear whether these MoCA scores can differentiate between distinct clinical dementia syndromes. This study compared MoCA Index scores between amnestic dementia of the Alzheimer’s type (DAT) and primary progressive aphasia (PPA), a language-based dementia.Method:Baseline MoCA data were analyzed from 33 DAT, 37 PPA, and 83 cognitively normal individuals enrolled in the Clinical Core of the Northwestern Alzheimer’s Disease Center. A one-way analysis of covariance adjusted for age was used to compare MoCA scores among groups. A logistic regression model was implemented to observe individual likelihood of group affiliation based on MoCA Index scores.Results:The mean MoCA total score was significantly higher in controls compared to both patient groups (p < .001) but did not differ between DAT and PPA groups. However, in accordance with salient clinical features commonly observed in DAT versus PPA, Memory and Orientation Index scores were lowest in the DAT group (p < .001), whereas Language and Attention Index scores were lowest in the PPA group (p < .001). Multivariate logistic regression analysis showed that the individual effects of Memory (p = .001), Language (p = .002), and Orientation (p = .025) Indices were significant.Conclusions:MoCA Index scores can help differentiate among distinct cognitive syndromes, suggesting it may be a useful brief screening tool to detect domain-specific cognitive impairment.