This study aims to identify outdoor thermal benchmarks of shaded spaces in an urban park in Xi'an (China). Meteorological measurements were conducted during winter and summer accompanied by a ...subjective thermal sensation questionnaire. The Universal Thermal Climate Index (UTCI) was applied to quantitatively analyze the thermal comfort range in Xi'an, and then variations in outdoor thermal benchmarks between Xi'an and other climatic zones were compared. Results demonstrated that: (1) Air temperature and globe temperature were the dominant physical factors affecting outdoor thermal comfort (OTC) in Xi'an. (2) Pavilion shade effectively lowered thermal stress, decreasing UTCI by 15.5 and 10.1 °C during winter and summer. (3) Deciduous tree shade was the optimal shading design measure and could meet demands for thermally comfortable environments. (4) The neutral UTCI in Xi'an was found to be 23.1 °C, and the acceptable UTCI ranged from 18.0 to 29.1 °C, and (5) a thermal comfort calendar for shaded spaces demonstrated that “strong cold stress” or higher occurred after 16:00h in winter. Pavilion and deciduous tree shades were “neutral thermal stress” for 24h in summer. The results identify thermal benchmarks that could help urban designers create thermally comfortable outdoor spaces in urban parks within the cold region of China.
•Thermal comfort conditions of shaded spaces in Xi'an, China were investigated.•Ta and Tg were the dominant physical factors affecting OTC in Xi'an.•UTCI satisfactorily predicted OTC with neutral value of 23.1 °C.•The range of acceptable neutral UTCI stretched from 18.0 °C to 29.1 °C.•A thermal comfort calendar was proposed for leisure and recreational activities.
Abstract One of the most important aspects of being in urban spaces, which creates vitality and increases it among citizens, is spaces such as urban squares. Today, several factors have caused the ...squares to lose their efficiency as an urban space to visit and become a geometric space for vehicles to pass. In this research, survey, field, interview and questionnaire methods have been used. According to the results, what turns a place into a welcoming space is not only its physical dimension, but also the social dimension of this place by creating vitality by considering the criteria of civil rights, which leads to the formation of a populist urban space. In this way, people of all ages can be reunited, creating face-to-face relationships and increasing social interactions. In general, no desirable urban quality, including the creation of a sense of belonging and vitality in urban squares, can be the product of an event. The vitality of a space is derived from a chain of activities, logical, coordinated and program-oriented actions.
Abstract
We consider the orbital evolution of satellites in galaxy mergers, focusing on the evolution of eccentricity. Using a large suite of
N
-body simulations, we study the phenomenon of satellite ...orbital radialization—a profound increase in the eccentricity of its orbit as it decays under dynamical friction. While radialization is detected in a variety of different setups, it is most efficient in cases of high satellite mass, not very steep host density profiles, and high initial eccentricity. To understand the origin of this phenomenon, we run additional simulations with various physical factors selectively turned off: satellite mass loss, reflex motion and distortion of the host, etc. We find that all these factors are important for radialization because it does not occur for point-mass satellites or when the host potential is replaced with an unperturbed initial profile. The analysis of forces and torques acting on both galaxies confirms the major role of self-gravity of both host and satellite in the reduction of orbital angular momentum. The classical Chandrasekhar dynamical friction formula, which accounts only for the forces between the host and the satellite, but not for internal distortions of both galaxies, does not match the evolution of eccentricity observed in
N
-body simulations.
For the high-speed permanent magnet synchronous motors (HSPMSMs), their magnetic fields are more complicated with the rotating magnetization and harmonics considered. Furthermore, there are ...interaction effects on motor iron loss from high frequency, temperature, and compressive stress. In order to obtain the accurate HSPMSM iron loss calculation model, different iron loss models are proposed, in this article, considering these physical factors, and the iron loss model considering the interaction effect of the multiphysics factors is given. The magnetic field, temperature field, and stress field are analyzed for HSPMSM by finite-element method (FEM). Then, the proposed models are employed to calculate the iron loss of the silicon steel sheet and the prototype. The accuracy of the proposed iron loss model, which can consider the interaction effect of the multiphysics factors, is verified by the experimental test measurements on the prototype.
How Dihalogens Catalyze Michael Addition Reactions Hamlin, Trevor A.; Fernández, Israel; Bickelhaupt, F. Matthias
Angewandte Chemie (International ed.),
June 24, 2019, Letnik:
58, Številka:
26
Journal Article
Recenzirano
Odprti dostop
We have quantum chemically analyzed the catalytic effect of dihalogen molecules (X2=F2, Cl2, Br2, and I2) on the aza‐Michael addition of pyrrolidine and methyl acrylate using relativistic density ...functional theory and coupled‐cluster theory. Our state‐of‐the‐art computations reveal that activation barriers systematically decrease as one goes to heavier dihalogens, from 9.4 kcal mol−1 for F2 to 5.7 kcal mol−1 for I2. Activation strain and bonding analyses identify an unexpected physical factor that controls the computed reactivity trends, namely, Pauli repulsion between the nucleophile and Michael acceptor. Thus, dihalogens do not accelerate Michael additions by the commonly accepted mechanism of an enhanced donor–acceptor HOMO(nucleophile)–LUMO(Michael acceptor) interaction, but instead through a diminished Pauli repulsion between the lone‐pair of the nucleophile and the Michael acceptor's π‐electron system.
Pauli rules! The catalytic effect of dihalogen molecules on Michael addition reactions increases along the series: X2=F2<Cl2<Br2<I2. Quantum chemical activation strain analyses reveal that the physical mechanism behind this dihalogen catalysis is a reduced Pauli repulsion between reactants, not the commonly assumed enhanced HOMO(nucleophile)–LUMO(Michael acceptor) interaction.
Frailty is one of the greatest challenges facing our aging population, as it can lead to adverse outcomes such as institutionalization, hospitalization, and mortality. However, the factors that are ...associated with frailty are poorly understood. We performed a systematic review of longitudinal studies in order to identify the sociodemographic, physical, biological, lifestyle-related, and psychological risk or protective factors that are associated with frailty among community-dwelling older adults.
A systematic literature search was conducted in the following databases in order to identify studies that assessed the factors associated with of frailty among community-dwelling older adults: Embase, Medline Ovid, Web of Science, Cochrane, PsychINFO Ovid, CINAHL EBSCOhost, and Google Scholar. Studies were selected if they included a longitudinal design, focused on community-dwelling older adults aged 60 years and older, and used a tool to assess frailty. The methodological quality of each study was assessed using the Quality of Reporting of Observational Longitudinal Research checklist.
Twenty-three studies were included. Significant associations were reported between the following types of factors and frailty: sociodemographic factors (7/7 studies), physical factors (5/6 studies), biological factors (5/7 studies), lifestyle factors (11/13 studies), and psychological factors (7/8 studies). Significant sociodemographic factors included older age, ethnic background, neighborhood, and access to private insurance or Medicare; significant physical factors included obesity and activities of daily living (ADL) functional status; significant biological factors included serum uric acid; significant lifestyle factors included a higher Diet Quality Index International (DQI) score, higher fruit/vegetable consumption and higher tertile of all measures of habitual dietary resveratrol exposure; significant psychological factors included depressive symptoms.
A broad range of sociodemographic, physical, biological, lifestyle, and psychological factors show a longitudinal association with frailty. These factors should be considered when developing interventions aimed at preventing and/or reducing the burden associated with frailty among community-dwelling older adults.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Practitioners and decision makers in the medical and insurance systems need knowledge on the relationship between work exposures and burnout. Many burnout studies - original as well as reviews - ...restricted their analyses to emotional exhaustion or did not report results on cynicism, personal accomplishment or global burnout. To meet this need we carried out this review and meta-analyses with the aim to provide systematically graded evidence for associations between working conditions and near-future development of burnout symptoms.
A wide range of work exposure factors was screened. Inclusion criteria were: 1) Study performed in Europe, North America, Australia and New Zealand 1990-2013. 2) Prospective or comparable case control design. 3) Assessments of exposure (work) and outcome at baseline and at least once again during follow up 1-5 years later. Twenty-five articles met the predefined relevance and quality criteria. The GRADE-system with its 4-grade evidence scale was used.
Most of the 25 studies focused emotional exhaustion, fewer cynicism and still fewer personal accomplishment. Moderately strong evidence (grade 3) was concluded for the association between job control and reduced emotional exhaustion and between low workplace support and increased emotional exhaustion. Limited evidence (grade 2) was found for the associations between workplace justice, demands, high work load, low reward, low supervisor support, low co-worker support, job insecurity and change in emotional exhaustion. Cynicism was associated with most of these work factors. Reduced personal accomplishment was only associated with low reward. There were few prospective studies with sufficient quality on adverse chemical, biological and physical factors and burnout.
While high levels of job support and workplace justice were protective for emotional exhaustion, high demands, low job control, high work load, low reward and job insecurity increased the risk for developing exhaustion. Our approach with a wide range of work exposure factors analysed in relation to the separate dimensions of burnout expanded the knowledge of associations, evidence as well as research needs. The potential of organizational interventions is illustrated by the findings that burnout symptoms are strongly influenced by structural factors such as job demands, support and the possibility to exert control.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Spatiotemporal distribution patterns of microplastic (MP) particles in lakes hinge on both the physical conditions in the lake and particle properties. Using numerical simulations, we systematically ...investigated the influence of lake depth and bathymetry, wind and temperature conditions, MP particle release location and timing, as well as particle diameter (10, 20, and 50 μm). Our results indicate that maximum lake depth had the greatest effect on the residence time in the water column, as it determines the settling timescale and occurrence of hydrodynamic complexity such as density-driven flows in the lake. Increasing particle size from 10 to 20 and 50 μm also significantly reduced the residence time making particle size the factor with the second strongest effect on the residence time and, in turn, on the availability of MP particles for uptake by organisms. Changing bathymetry from a uniform to a non-uniform had a less pronounced effect on particle residence time compared to maximum depth and particle size. Release location, wind conditions, and release time had comparably little effect on particle behavior but became more important as MP particle size decreased. The release of the 10 μm MP particles in the deeper lakes with uniform bathymetry during summer with stable thermal stratification, resulted in a nearly month-long turnover phase in the fall in which both settling and rising of particles occurred simultaneously. This was caused by convective heat and water transport during this period. In these scenarios about 2.6 to 5.4 % of the released MP particles were held in or returned to the water layers near the lake surface. While acknowledging the dominant role of lake depth and MP particle size on the particle residence time, this study further emphasizes that it is ultimately a particular combination of different factors and their interactions that shape MP distribution patterns in lakes.
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•Lake depth, bathymetry, and particle size are dominant controls of MP fate.•Impact of wind, release location/time on MP fate grows with decreasing MP size.•Dissipation of thermal stratification increases odds of rising for 10 μm particles.•Assessing MP fate needs evaluation of all physical factors and their interactions.
The purpose of this study was to investigate the degree of relative age effect (RAE) among the best Norwegian track and field athletes of all time, aged 13 years to senior, as well as to investigate ...the differences between athletes in events that impose different demands on their physical characteristics, categorised in endurance and explosiveness. The degree of RAE was investigated by examining the difference between the sample’s (
N
= 21,711) quarterly birth distribution and the quarterly distribution of birth of the Norwegian population as a whole from 1966 to 2019. To determine whether or not an RAE was present, chi-square tests (χ
2
) were conducted against an even distribution, with Cramer’s V (phi or
ɸ
) as a measure of effect size. The study’s results show a strong RAE in the two youngest age groups in both genders. RAE decreases with increasing age, but the effect is still present at the senior level in both men and women. Furthermore, the degree of RAE was strongest in explosive events in both boys (
ɸ
= 0.46) and girls (
ɸ
= 0.30), while in endurance events it was strong in boys (
ɸ
= 0.38) but not in girls (
ɸ
= 0.13). Prominent effect of RAE in the 13- and 14-year-old classes can be explained by the fact that in the youngest age groups impose the highest relative age difference. In addition, this is an age group where there are large differences in growth spurts, physical characteristics and training experience. Elimination of RAE with increasing age may be due to the fact that after puberty inherent physical advantages as a result of the month of birth are evened out. The prominent RAE in explosive events and in boys may be due to the fact that puberty and growth spurts make boys faster, stronger and larger, while puberty and growth spurts in girls are not always beneficial for girls in track and field events. The practical significance of the results relates to athletes developmental opportunities. Irrespective of whether young track and field athletes are relatively older or younger they should be met with patience and dedication from coaches. Superficial short-term categorization of young athletes potential do more harm than good.
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