69 research outputs found
A case for considering age and sex when prescribing rest intervals in resistance training
Current resistance training position stands recommend that rest interval duration in resistance training should be prescribed based on the training goal and exercise selection. However, these recommendations are mostly extrapolated from studies that included young men as participants. Therefore, they cannot be generalized to all age groups and all resistance training programs. Herein, two overlooked, but possibly important factors for rest interval prescription are discussed: (1) age, and (2) sex of the individual. Acute studies indicate that older adults, as compared to young adults, require a shorter duration rest interval to achieve recovery between sets. Due to the sex differences in fatigability, it can be speculated that men need a longer duration rest interval than women to maintain high levels of performance. Both sex and age may be relevant variables when determining rest interval duration in resistance exercise and should not be overlooked by exercise practitioners in program design
Coupled-resonator optical waveguides: Q-factor and disorder influence
Coupled resonator optical waveguides (CROW) can significantly reduce light
propagation pulse velocity due to pronounced dispersion properties. A number of
interesting applications have been proposed to benefit from such slow-light
propagation. Unfortunately, the inevitable presence of disorder, imperfections,
and a finite Q value may heavily affect the otherwise attractive properties of
CROWs. We show how finite a Q factor limits the maximum attainable group delay
time; the group index is limited by Q, but equally important the feasible
device length is itself also limited by damping resulting from a finite Q.
Adding the additional effects of disorder to this picture, limitations become
even more severe due to destructive interference phenomena, eventually in the
form of Anderson localization. Simple analytical considerations demonstrate
that the maximum attainable delay time in CROWs is limited by the intrinsic
photon lifetime of a single resonator.Comment: Accepted for Opt. Quant. Electro
Multi-Atomic Mirror for Perfect Reflection of Single Photons in A Wide Band of Frequency
A resonant two level atom doped in one dimensional waveguide behaves as a
mirror, but this single-atom "mirror" can only reflect single photon perfectly
at a specific frequency. For a one dimensional coupled-resonator waveguide, we
propose to extend the perfect reflection region from a specific frequency to a
wide band by placing many atoms individually in the resonators in a finite
coordinate region of the waveguide. Such a doped resonator array promises us to
control the propagation of a practical photon wave packet with certain momentum
distribution instead of a single photon, which is ideally represented by a
plane wave with specific momentum. The studies based on the discrete-coordinate
scattering theory display that such hybrid structure indeed provides a
near-perfect reflection for single photon in a wide band. We also calculated
photon group velocity distribution, which shows that the perfect reflection
with wide band exactly corresponds to the stopping light region.Comment: 8 pages, 10 figure
“Look! It’s a Computer Program! It’s an Algorithm! It’s AI!”: Does Terminology Affect Human Perceptions and Evaluations of Algorithmic Decision-Making Systems?
In the media, in policy-making, but also in research articles, algorithmic decision-making (ADM) systems are referred to as algorithms, artificial intelligence, and computer programs, amongst other terms. We hypothesize that such terminological differences can affect people’s perceptions of properties of ADM systems, people’s evaluations of systems in application contexts, and the replicability of research as findings may be influenced by terminological differences. In two studies (N = 397, N = 622), we show that terminology does indeed affect laypeople’s perceptions of system properties (e.g., perceived complexity) and evaluations of systems (e.g., trust). Our findings highlight the need to be mindful when choosing terms to describe ADM systems, because terminology can have unintended consequences, and may impact the robustness and replicability of HCI research. Additionally, our findings indicate that terminology can be used strategically (e.g., in communication about ADM systems) to influence people’s perceptions and evaluations of these systems
A case for considering age and sex when prescribing rest intervals in resistance training
Current resistance training position stands recommend that rest interval duration in resistance training should be prescribed based on the training goal and exercise selection. However, these recommendations are mostly extrapolated from studies that included young men as participants. Therefore, they cannot be generalized to all age groups and all resistance training programs. Herein, two overlooked, but possibly important factors for rest interval prescription are discussed: (1) age, and (2) sex of the individual. Acute studies indicate that older adults, as compared to young adults, require a shorter duration rest interval to achieve recovery between sets. Due to the sex differences in fatigability, it can be speculated that men need a longer duration rest interval than women to maintain high levels of performance. Both sex and age may be relevant variables when determining rest interval duration in resistance exercise and should not be overlooked by exercise practitioners in program design
Quantitative thermal imaging using single-pixel Si APD and MEMS mirror
Accurate quantitative temperature measurements are difficult to achieve using
focal-plane array sensors. This is due to reflections inside the instrument and the difficulty of
calibrating a matrix of pixels as identical radiation thermometers. Size-of-source effect (SSE),
which is the dependence of an infrared temperature measurement on the area surrounding the
target area, is a major contributor to this problem and cannot be reduced using glare stops.
Measurements are affected by power received from outside the field-of-view (FOV), leading
to increased measurement uncertainty. In this work, we present a micromechanical systems
(MEMS) mirror based scanning thermal imaging camera with reduced measurement
uncertainty compared to focal-plane array based systems. We demonstrate our flexible
imaging approach using a Si avalanche photodiode (APD), which utilises high internal gain to
enable the measurement of lower target temperatures with an effective wavelength of 1 µm
and compare results with a Si photodiode. We compare measurements from our APD thermal
imaging instrument against a commercial bolometer based focal-plane array camera. Our
scanning approach results in a reduction in SSE related temperature error by 66 °C for the
measurement of a spatially uniform 800 °C target when the target aperture diameter is
increased from 10 to 20 mm. We also find that our APD instrument is capable of measuring
target temperatures below 700 °C, over these near infrared wavelengths, with D* related
measurement uncertainty of ± 0.5 °C
Laser ablation ICP-MS of size-segregated atmospheric particles collected with a MOUDI cascade impactor: a proof of concept
A widely used instrument for collecting size-segregated particles
is the micro-orifice uniform deposit impactor (MOUDI). In this work, a
10-stage MOUDI (cut-point diameter of 10 µm to 56 nm) was used to collect
samples in Ljubljana, Slovenia, and Martinska, Croatia. Filters, collected
with and without rotation, were cut in half and analyzed for nine elements
(As, Cu, Fe, Ni, Mn, Pb, Sb, V, Zn) using laser ablation ICP-MS. Elemental
image maps (created with ImageJ) were converted to concentrations using NIST
SRM 2783. Statistical analysis of the elemental maps indicated that for
submicron particles (stages 6–10), ablating 10 % of the filter (0.5 cm2, 20 min ablation time) was sufficient to give values in good
agreement (±10 %) to analysis of larger parts of the filter and
with good precision (RSE < 1 %). Excellent sensitivity
was also observed (e.g., 20 ± 0.2 pg m−3 V). The novel use of LA-ICP-MS, together with image mapping, provided a fast and sensitive method for
elemental analysis of size-segregated MOUDI filters, particularly for
submicron particles
Metal transfer to sediments, invertebrates and fish following waterborne exposure to silver nitrate or silver sulfide nanoparticles in an indoor stream mesocosm.
The fate of engineered nanomaterials in ecosystems is unclear. An aquatic stream mesocosm was explored the fate and bioaccumulation of silver sulfide nanoparticles (Ag2S NPs) compared to silver nitrate (AgNO3). The aims were to determine the total Ag in water, sediment and biota, and to evaluate the bioavailable fractions of silver in the sediment using a serial extraction method. The total Ag in the water column from a nominal daily dose of 10 μg L-1 of Ag for the AgNO3 or Ag2S NP treatments reached a plateau of around 13 and 12 μg L-1, respectively, by the end of the study. Similarly, the sediment of both Ag-treatments reached ~380 μg Ag kg-1, and with most of it being acid-extractable/labile. The biota accumulated 4-59 μg Ag g-1 dw, depending on the type of Ag-treatment and organism. The oligochaete worm, Lumbriculus variegatus, accumulated Ag from the Ag2S exposure over time, which was similar to the AgNO3 treatment by the end of the experiment. The planarian, Girardia tigrina, and the chironomid larva, Chironomus riparius, showed much higher Ag concentrations than the oligochaete worms; and with a clearer time-dependent statistically significant Ag accumulation relative to the untreated controls. For the pulmonated snail, Physa acuta, bioaccumulation of Ag from AgNO3 and Ag2S NP exposures was observed, but was lower from the nano treatment. The AgNO3 exposure caused appreciable Ag accumulation in the water flea, Daphnia magna, but accumulation was higher in the Ag2S NP treatment (reaching 59 μg g-1 dw). In the rainbow trout, Oncorhynchus mykiss, AgNO3, but not Ag2S NPs, caused total Ag concentrations to increase in the tissues. Overall, the study showed transfer of total Ag from the water column to the sediment, and Ag bioaccumulation in the biota, with Ag from Ag2S NP exposure generally being less bioavailable than that from AgNO3
Urine-based testing for Chlamydia trachomatis among young adults in a population-based survey in Croatia: Feasibility and prevalence
<p>Abstract</p> <p>Background</p> <p>We assessed the feasibility of collecting urine samples for testing on genital <it>Chlamydia trachomatis </it>infection in a population-based survey, and prevalence of this infection among young people aged 18-25 in Croatia. In Croatia, as in the other countries of Eastern Europe, there is a lack of data on prevalence of <it>C trachomatis </it>in the general population, including young adults.</p> <p>Methods</p> <p>We sampled participants using a nationally representative, multi-stage stratified probability sample of young men and women. Detection of <it>C trachomatis </it>DNA in urine samples was performed by using a real-time PCR assay COBAS<sup>® </sup>TaqMan<sup>® </sup>CT Test, v2.0.</p> <p>Results</p> <p>Overall, 1005 young adults participated in the behavioural part of the survey, and 27.9% men and 37.5% women who were sexually experienced agreed to provide urine samples for testing on <it>C trachomatis</it>. Using multivariate analysis, women were significantly more likely to provide urine samples than men (aOR = 1.53, 95% CI 1.14-2.06) as were those who reported no condom use at last intercourse (aOR = 1.95, 95% CI 1.44-2.62). Prevalence of <it>C trachomatis </it>infection among those who were sexually experienced was 7.3% in men and 5.3% in women.</p> <p>Conclusions</p> <p>Population-based surveys that use probabilistic sampling are a feasible way to obtain population estimates of <it>C trachomatis </it>prevalence among young adults in Croatia, but it is challenging to obtain an adequate response rate. The prevalence of <it>C trachomatis </it>among young adults in Croatia found in this study was higher than that found in other European countries with similar survey response rates.</p
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