Invisibility in billiards

The question of invisibility for bodies with mirror surface is studied in the framework of geometrical optics. We construct bodies that are invisible/have zero resistance in two mutually orthogonal directions, and prove that there do not exist bodies which are invisible/have zero resistance in all possible directions of incidence

Modeling tourists' personality in recommender systems: how does personality influence preferences for tourist attractions?

Personalization is increasingly being perceived as an important factor for the effectiveness of Recommender Systems (RS). This is especially true in the tourism domain, where travelling comprises emotionally charged experiences, and therefore, the more about the tourist is known, better recommendations can be made. The inclusion of psychological aspects to generate recommendations, such as personality, is a growing trend in RS and they are being studied to provide more personalized approaches. However, although many studies on the psychology of tourism exist, studies on the prediction of tourist preferences based on their personality are limited. Therefore, we undertook a large-scale study in order to determine how the Big Five personality dimensions influence tourists' preferences for tourist attractions, gathering data from an online questionnaire, sent to Portuguese individuals from the academic sector and their respective relatives/friends (n=508). Using Exploratory and Confirmatory Factor Analysis, we extracted 11 main categories of tourist attractions and analyzed which personality dimensions were predictors (or not) of preferences for those tourist attractions. As a result, we propose the first model that relates the five personality dimensions with preferences for tourist attractions, which intends to offer a base for researchers of RS for tourism to automatically model tourist preferences based on their personality.GrouPlanner Project under the European Regional Development Fund POCI-01-0145-FEDER29178 and by National Funds through the FCT – Fundação para a Ciência e a Tecnologia (Portuguese Foundation for Science and Technology) within the Projects UIDB/00319/2020 and UIDB/00760/202

Особенности мозговой активности при алкогольной зависимости в задаче на ингибиторный контроль

Objective. To study neurophysiological correlates of inhibitory control to determine the features of inhibitionprocesses in alcohol dependence.Materials and methods. 77 patients with alcohol dependence were examined (42 men and 35 women) (F10.2 according to ICD-10). Patients were examined using a test to assess inhibitory control – Go/No – go. According to the task performance, patients were divided into two groups: group 1 – without inhibitory control impairments, group 2 – with impaired inhibitory control. During execution of test, electroencephalogram recordings were made according to the 10–20 system. The values of spectral power and coherence of θ-, α- and β-rhythms were analyzed. Statistical processing was carried out using nonparametric Mann–Whitney U-test and Wilcoxon W-test.Results. In patients with impaired inhibitory control, there was a decrease in the spectral power of the α-rhythm in the frontal cortex (p = 0.003), whereas in patients without inhibitory control disorders – in the Central cortex (p = 0.036). Patients with impaired inhibitory control responded by increasing β-power to cognitive stimulus in the occipital (p = 0.014), left temporal (p = 0.009) and right temporal (p = 0.008) cortex, while patients without inhibitory control disorders showed an increase in β-power only in the occipital (p = 0.007) and left temporal (p = 0.002) cortex. According to coherence data, patients with impaired inhibitory control have greater involvement of brain structures during the “Go/No – go” test in all frequency ranges.Conclusions. Patients with and without impaired inhibitory control have regional differences in changes in brain bioelectric activity during the “Go/No – go” test.Цель. Изучить нейрофизиологические корреляты ингибиторного контроля для определения особенностей процессов торможения при алкогольной зависимости.Материалы и методы. Обследованы 77 пациентов (42 мужчины и 35 женщин) с  алкогольной зависимостью (F10.2 по МКБ-10). Пациенты обследованы с помощью теста  для оценки ингибиторного контроля – Go/No – go. По результатам этого теста пациенты были разделены на две группы: группа 1 – без нарушения ингибиторного контроля, группа 2 – с нарушением ингибиторного контроля. Во время выполнения теста проводилась запись электроэнцефалограммы по системе «10–20». Анализировались значения спектральной мощности и когерентности θ-, α- и β-ритмов.  Статистическая обработка проводилась с применением непараметрического U-критерия Манна – Уитни и W-критерия Вилкоксона.Результаты. У пациентов с нарушенным ингибиторным контролем происходило снижение спектральной мощности α-ритма во фронтальной коре головного мозга (р = 0,003), тогда как у пациентов без нарушений ингибиторного контроля – в центральной  коре (р = 0,036). Пациенты с нарушенным ингибиторным контролем реагировали повышением β-мощности на когнитивный стимул в затылочной (р = 0,014), левой височной (р = 0,009) и правой височной (р = 0,008) коре, при этом у пациентов без нарушений ингибиторного контроля наблюдалось повышение β-мощности только в  затылочной (р = 0,007) и левой височной (р = 0,002) коре. По данным когерентности, у пациентов с нарушением ингибиторного контроля наблюдается большая вовлеченность  мозговых структур во время выполнения теста Go/No – go во всех частотных диапазонах.Заключение. Пациенты с нарушением и без нарушения ингибиторного контроля имеют региональные различия в изменениях биоэлектрической активности головного мозга в процессе выполнения теста Go/No – go

A new design for a green calcium indicator with a smaller size and a reduced number of calcium-binding sites

Genetically encoded calcium indicators (GECIs) are mainly represented by two- or one-fluorophore-based sensors. One type of two-fluorophore-based sensor, carrying Opsanus troponin C (TnC) as the Ca2+-binding moiety, has two binding sites for calcium ions, providing a linear response to calcium ions. One-fluorophore-based sensors have four Ca2+-binding sites but are better suited for in vivo experiments. Herein, we describe a novel design for a one-fluorophore-based GECI with two Ca2+-binding sites. The engineered sensor, called NTnC, uses TnC as the Ca2+-binding moiety, inserted in the mNeonGreen fluorescent protein. Monomeric NTnC has higher brightness and pH-stability in vitro compared with the standard GECI GCaMP6s. In addition, NTnC shows an inverted fluorescence response to Ca2+. Using NTnC, we have visualized Ca2+ dynamics during spontaneous activity of neuronal cultures as confirmed by control NTnC and its mutant, in which the affinity to Ca2+ is eliminated. Using whole-cell patch clamp, we have demonstrated that NTnC dynamics in neurons are similar to those of GCaMP6s and allow robust detection of single action potentials. Finally, we have used NTnC to visualize Ca2+ neuronal activity in vivo in the V1 cortical area in awake and freely moving mice using two-photon microscopy or an nVista miniaturized microscope

Alleviating the new user problem in collaborative filtering by exploiting personality information

The final publication is available at Springer via http://dx.doi.org/10.1007/s11257-016-9172-zThe new user problem in recommender systems is still challenging, and there is not yet a unique solution that can be applied in any domain or situation. In this paper we analyze viable solutions to the new user problem in collaborative filtering (CF) that are based on the exploitation of user personality information: (a) personality-based CF, which directly improves the recommendation prediction model by incorporating user personality information, (b) personality-based active learning, which utilizes personality information for identifying additional useful preference data in the target recommendation domain to be elicited from the user, and (c) personality-based cross-domain recommendation, which exploits personality information to better use user preference data from auxiliary domains which can be used to compensate the lack of user preference data in the target domain. We benchmark the effectiveness of these methods on large datasets that span several domains, namely movies, music and books. Our results show that personality-aware methods achieve performance improvements that range from 6 to 94 % for users completely new to the system, while increasing the novelty of the recommended items by 3-40 % with respect to the non-personalized popularity baseline. We also discuss the limitations of our approach and the situations in which the proposed methods can be better applied, hence providing guidelines for researchers and practitioners in the field.This work was supported by the Spanish Ministry of Economy and Competitiveness (TIN2013-47090-C3). We thank Michal Kosinski and David Stillwell for their attention regarding the dataset

Late pleistocene sedimentation history of the Shirshov Ridge, Bering Sea

The analysis of the lithology, grain-size distribution, clay minerals, and geochemistry of Upper Pleistocene sediments from the submarine Shirshov Ridge (Bering Sea) showed that the main source area was the Yukon–Tanana terrane of Central Alaska. The sedimentary materials were transported by the Yukon River through Beringia up to the shelf break, where they were entrained by a strong northwestward-flowing sea current. The lithological data revealed several pulses of ice-rafted debris deposition, roughly synchronous with Heinrich events, and periods of weaker bottom-current intensity. Based on the geochemical results, we distinguished intervals of an increase in paleoproductivity and extension of the oxygen minimum zone. The results suggest that there were three stages of deposition driven by glacioeustatic sea-level fluctuations and glacial cycles in Alaska

Влияние лазерной коррекции на гидратную оболочку биоструктур клеток миокарда и печени при массивной кровопотере

Acute rat experiments have studied the impact of acute blood loss on the distribution of water fractions (total, free, and bound) in myocardial and hepatic tissues and whether detected impairments can be corrected by laser irradiation. They have provided an insight into the new pathogenetic mechanisms responsible for homeostatic disorders in blood loss and some aspects of the mechanism of action of laser emission on the body’s adaptive processes. The functioning of biopolymers and molecular structures in tissues is largely determined by their content of water. The redistribution of water towards to a blood loss-associated increase in bound water is a compensatory reaction aimed at preserving the biological structure of biopoly-mers. The decrease in hydrant-bound water suggests that there are severe derangements of their structure. The changes in the tissue free/bound water ratio reflect the degree of the body’s dysadaptation to blood loss. Laser irradiation has an adap-togenic effect on the structure of water in compensated hemorrhagic shock and a damaging action in decompensated one. В острых экспериментах на крысах изучено влияние острой кровопотери на распределение фракций воды (общей, свободной и связанной) в тканях миокарда и печени и возможность коррекции отмеченных нарушений лазерным излучением. Результаты экспериментов позволили раскрыть новые патогенетические механизмы нарушений гомеостаза при кровопотере и некоторые стороны механизма действия лазерного излучения на адаптивные процессы в организме. Показано, что функционирование биополимеров и молекулярных структур в тканях в значительной мере определяется содержанием в них воды. Перераспределение воды в сторону увеличения связанной при кровопотере является компенсаторной реакцией, направленной на сохранение биоструктуры биополимеров. Уменьшение гидратно связанной воды свидетельствует о глубоких нарушениях их структуры. Изменения в соотношении свободной и связанной воды в тканях отражает степень дезадаптации организма к кровопотере. Лазерное излучение оказывает адаптогенное действие на структуру воды при компенсированном геморрагическом шоке и повреждающее — при декомпенсированном

Identifying human diamine sensors for death related putrescine and cadaverine molecules

Pungent chemical compounds originating from decaying tissue are strong drivers of animal behavior. Two of the best-characterized death smell components are putrescine (PUT) and cadaverine (CAD), foul-smelling molecules produced by decarboxylation of amino acids during decomposition. These volatile polyamines act as 'necromones', triggering avoidance or attractive responses, which are fundamental for the survival of a wide range of species. The few studies that have attempted to identify the cognate receptors for these molecules have suggested the involvement of the seven-helix trace amine-associated receptors (TAARs), localized in the olfactory epithelium. However, very little is known about the precise chemosensory receptors that sense these compounds in the majority of organisms and the molecular basis of their interactions. In this work, we have used computational strategies to characterize the binding between PUT and CAD with the TAAR6 and TAAR8 human receptors. Sequence analysis, homology modeling, docking and molecular dynamics studies suggest a tandem of negatively charged aspartates in the binding pocket of these receptors which are likely to be involved in the recognition of these small biogenic diamines

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700