The success of advanced quantum communication relies crucially on non-classical light sources emitting single indistinguishable photons at high flux rates and purity. We report on deterministically ...fabricated microlenses with single quantum dots inside which fulfil these requirements in a flexible and robust quantum device approach. In our concept we combine cathodoluminescence spectroscopy with advanced in situ three-dimensional electron-beam lithography at cryogenic temperatures to pattern monolithic microlenses precisely aligned to pre-selected single quantum dots above a distributed Bragg reflector. We demonstrate that the resulting deterministic quantum-dot microlenses enhance the photon-extraction efficiency to (23±3)%. Furthermore we prove that such microlenses assure close to pure emission of triggered single photons with a high degree of photon indistinguishability up to (80±7)% at saturation. As a unique feature, both single-photon purity and photon indistinguishability are preserved at high excitation power and pulsed excitation, even above saturation of the quantum emitter.
Recognising that modifications to the physical attributes of urban space are able to promote improved thermal outdoor conditions and thus positively influence the use of open spaces, a survey to ...define optimal thermal comfort ranges for passers-by in pedestrian streets was conducted in Curitiba, Brazil. We applied general additive models to study the impact of temperature, humidity, and wind, as well as long-wave and short-wave radiant heat fluxes as summarised by the recently developed Universal Thermal Climate Index (UTCI) on the choice of clothing insulation by fitting LOESS smoothers to observations from 944 males and 710 females aged from 13 to 91 years. We further analysed votes of thermal sensation compared to predictions of UTCI. The results showed that females chose less insulating clothing in warm conditions compared to males and that observed values of clothing insulation depended on temperature, but also on season and potentially on solar radiation. The overall pattern of clothing choice was well reflected by UTCI, which also provided for good predictions of thermal sensation votes depending on the meteorological conditions. Analysing subgroups indicated that the goodness-of-fit of the UTCI was independent of gender and age, and with only limited influence of season and body composition as assessed by body mass index. This suggests that UTCI can serve as a suitable planning tool for urban thermal comfort in sub-tropical regions.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A composite with a high-alloy steel matrix was reinforced with varying amounts of Mg-PSZ and synthesized using Spark Plasma Sintering (SPS) technology. To prepare the powders for sintering, they were ...mixed in a planetary ball mill at two different rates of 100 rpm and 250 rpm. The influence of the rotation speed on the microstructures and compressive strengths of the sintered composites was investigated. Due to the high degree of deformation of the steel powder particles during milling at 250 rpm, the steel phase underwent grain refinement during SPS. Furthermore, the Mg-PSZ was more homogeneously distributed within the steel matrix and mechanically interlocked with the steel matrix. Thus, the compressive strength of the composite increased with increasing Mg-PSZ content and increasing rotation speed during milling of the powder due to grain refinement and the improved strength of the steel/ceramic interface. Furthermore, a larger amount of Mg-PSZ underwent stress-induced transformation under compressive loading.
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GEOZS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Urban climate can have severe impacts on people who use outdoor spaces within a city. In its essence, urban climate is directly linked to the configuration of street axes, building heights and their ...attributes. Thus, the role of urban planners can be crucial for guaranteeing outdoor thermal comfort and air quality in open spaces. This paper presents observed and estimated relations between urban morphology and changes in microclimate and air quality within a city center. Two approaches are presented, showing results of field measurements and urban climate simulations using the ENVI-met software suite. From measured microclimatic data and comfort surveys, carried out in downtown Curitiba, Brazil, the impact of street geometry on ambient temperatures and on daytime pedestrian comfort levels was evaluated, using the sky-view factor (SVF) as indicator of the complexity of the urban geometry. The impact of street orientation relative to prevailing winds and the resulting effects of ventilation (air speed and spatial distribution) on the dispersion of traffic-generated air pollutants were additionally analyzed by means of computer simulations. Results show the impact of urban geometry on human thermal comfort in pedestrian streets and on the outcomes of pollutant dispersion scenarios.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This study examines a quenched and partitioned steel matrix composite, which was reinforced with 10 vol% Mg-PSZ and processed by Spark Plasma Sintering (SPS). The investigations focused specifically ...on the effect of solution annealing prior to Quenching and Partitioning (Q&P) treatment on the microstructure and the mechanical properties under compressive loading of the composite. The results revealed that the solution annealing step is necessary to form α′-martensite after quenching during the Q&P treatment, which strengthens the material. Furthermore, a substantial amount of Mg-PSZ was found to have transformed in a stress-induced manner under compressive load if a certain fraction of α′-martensite was present in the initial microstructure. However, the solution annealing slightly intensified the destabilization of the Mg-PSZ.
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GEOZS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PURPOSEThe assessment of power changes after fatiguing exercise provides important additional information about neuromuscular function compared to traditional isometric measurements, especially when ...exploring age-related changes in fatigability. Therefore, the aim of this review was to explore the effects of age on neuromuscular fatigue (NMF) when measured in isometric compared with dynamic contractions. The importance of central and peripheral mechanisms contributing to age-related NMF were discussed.
METHODSMedline, EMBASE, Cochrane Central Register of Controlled Trials, and SPORT Discus databases were searched. The combination of terms related to the intervention (fatiguing exercise), population (old people) and outcomes (isometric force and power) were used. This meta-analysis was registered on PROSPERO (CRD42016048389).
RESULTSThirty-one studies were included. The meta-analyses revealed that force decrease was greater (there was more NMF) in young subjects than their older counterparts when fatigue was induced by isometric tasks (ES = 0.913, CI = 0.435 to 1.391, P < 0.001), but not when the fatiguing exercise was performed in dynamic mode (ES = 0.322, CI-0.039 to 0.682, P = 0.08). Older individuals demonstrated a greater reduction in power after fatigue induced by either dynamic or isometric tasks (ES = -0.891, CI–1.657 to -0.125, P = 0.023).
CONCLUSIONThere is no difference in the isometric force loss between young and old people when fatigue is induced by dynamic tasks. However, maximal power is more decreased following fatigue tasks in older adults. Thus, the assessment of fatigue (isometric force vs. power) must be considered in identifying age-related NMF mechanisms.
Outdoor thermal comfort (OTC) surveys require synchronous monitoring of meteorological variables for direct comparisons against subjective thermal perception. The Universal Thermal Climate Index ...(UTCI) is a feasible index as it integrates meteorological conditions as a single value irrespective of urban morphological attributes or biological sex, age and body mass. ERA5-HEAT (Human thErmAl comforT) is a downloadable reanalysis dataset providing hourly grids of UTCI climate records at 0.25° × 0.25° spatial resolution from 1979 to present. We here evaluate for the first time whether it is possible to use ERA5-HEAT data as a proxy for the UTCI measured onsite during OTC surveys. A dataset comprising 1640 survey responses gathered over 14 OTC campaigns in Curitiba, Brazil (25°26′S, 49°16′W) was analysed. We assessed the bias obtained between the Dynamic Thermal Sensation, an index derived from the UTCI, and the thermal sensation reported by survey participants by considering locally measured meteorological variables and ERA5-HEAT reanalysis data. As ERA5-HEAT data are given on an hourly basis, prediction bias can be greatly reduced when accounting for survey responses close to the hour. In terms of seasons, the fall and winter seasons have diminished mean bias, though with larger spread than in summer. In terms of UTCI stress categories, prediction bias is lower for the thermal comfort range. When comparing reanalysis data against WMO station data as proxy candidates for survey field data, the former presented lower bias, less spread in terms of standard deviation and higher correlation to
in situ
data.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Interactions between human beings and the built environment are mediated by physiological and psychological stimuli, which may interfere in the perception and satisfaction related to indoor comfort ...variables. The study aims to explore the relationship between daylighting features and possible impacts on humans in regards to lighting preferences. The influence of different daylighting configurations, glazed façade orientation and season of the year on lighting preferences in human beings was evaluated by means of tests in a rotating climate with monitoring of environmental variables, developed by the Karlsruhe Institute of Technology, Karlsruhe, Germany. The sample, n = 16, is composed of German male students (height SD = 1.80 m, SD = 0.06; body weight SD = 80 kg, SD = 8.9; and age SD = 24.9 years, SD = 3.6). Under controlled thermal conditions (PMV approx. ±0.5), participants remained in two office-like environments over 5 h (8:00 am to 1:00 pm - local time) three days in a row, for three seasons of the year, totaling nine days of data collection per participant. Definitions of glazed façade orientations for the experimental rounds were done by means of computer simulations. Objective variables were measured by spectroradiometers at desk height, with sensor h = ca. 0.90 m, and comfortmeters. Preferences of daylighting features was assessed by a questionnaire with Likert-scale alternatives, administered online at 8:50 am, 10:30 am and 12:30 pm. Objective and subjective data were analyzed statistically (Spearman's rho, rs), suggesting possible correlations between lighting preferences and objective variables, including: E (lx), CCT (K), DWl (nm) and the circadian metric acv (circadian action factor).
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•The higher the daylight availability, the lower the sensitivity of subjects to changes in light.•Despite benefits of lighting conditions to circadian functions, effects have not been observed on subjective preferences.•Subjective assessment is affected by variables other than CCT and DWl, with important contributions as well.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Thermal perception entails to a certain extent visual aspects, which are taken into account when subjects are requested to express their thermal votes to a given indoor or outdoor space. This study ...concentrates on human cognition and preconceptions of thermal behavior from projected 360° imagery. Urban scenes have been shown with the concurrent administration of thermal perception questionnaires to two distinct sample groups: 1) volunteer participants (n = 86) who filled out online responses to questions regarding thermal perception in undisclosed locations; 2) undergraduate students (n = 85) under temperature-controlled conditions in a computer lab. Both groups have evaluated three different 360° urban scenes with varying morphology attributes using the provided web link to the 360° VR platform Roundme. Method of analysis included means, medians, statistical significance (p-value) and percentage graphs of perceived thermal sensation. Despite the absence of any information regarding location, season and time of day of the scenes, both groups expressed different perceptions with respect to the estimated thermal conditions and thermal comfort levels for the observed urban scenes, consistently attributing windier and warmer thermal conditions to an urban square location and less so to a street canyon.
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•A similar trend in thermal perception was obtained for databases with remarkable differences.•Different protocols and samples suggest there is a context-related effect on thermal perception.•The outlook of a given outdoor space affects the way we perceive it thermally.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Cascaded quadratic nonlinearities from phase-mismatched second-harmonic generation build the foundation for robust soliton modelocking in straight-cavity laser configurations by providing a tunable ...and self-defocusing nonlinearity. The frequency dependence of the loss-related part of the corresponding nonlinear response function causes a power-dependent self-frequency shift (SFS). In this paper, we develop a simple analytical model for the SFS-induced changes on the carrier-envelope offset frequency ( f CEO ) and experimentally investigate the static and dynamic f CEO dependence on pump power. We find good agreement with the measured dependence of f CEO on laser output power, showing a broad f CEO tuning capability from zero up to the pulse repetition rate. Moreover, we stabilize the relative intensity noise to the −157 dBc/Hz level leading to a tenfold reduction in f CEO -linewidth.
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