Perceived Exertion in Physical Activity Measurement Across the Lifecourse: Results from SWAN

Physical activity (PA) guidelines recommend 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity PA, in addition to muscle strengthening activities, each week. Many questionnaires ascertain PA frequency, duration, and intensity to benchmark achievement of PA recommendations. However, most scoring algorithms utilize absolute intensity estimates when exertion may be influenced by age or other sociodemographic or health characteristics. This study compared PA estimates with and without adjustments for perceived exertion and determined if that difference was associated with individual characteristics. Women (n=2,711) from the longitudinal Study of Women’s Health Across the Nation who completed ≥3 Kaiser Physical Activity Surveys (KPAS) across 8 biennial visits were included (baseline age: 46.4±2.7 years). KPAS responses were converted to metabolic equivalent of a task (METs) using the Compendium of Physical Activities to estimate absolute and perceived intensity-adjusted MET values. Latent class growth modeling identified subgroups of participants following similar patterns of change in the difference between absolute intensity-based and perceived intensity-adjusted estimates across time. Four major trajectory classes emerged with patterns reflecting: (1) lessening high-intensity exercise (2.2%); (2) increasingly high-intensity exercise (3.1%); (3) consistently moderate-intensity exercise (92.0%); and (4) consistently low-intensity exercise (2.8%). Consistently low-intensity exercisers, for whom absolute intensity-based estimates exceeded perceived intensity-adjusted estimates, were more likely to be Japanese or Chinese (p<0.001) and have lower BMI (p=0.05). However, for most participants, absolute intensity-based estimates approximated perceived intensity-adjusted estimates over time, suggesting that traditional PA scoring techniques may provide sufficient estimates for PA in longitudinal cohort studies of mid-life and older adult women.

Label-Free Surface Enhanced Raman Scattering (SERS) on Centrifugal Silver Plasmonic Paper (CSPP): A Novel Methodology for Unprocessed Biofluids Sampling and Analysis

Label-free SERS is a powerful bio-analytical technique in which molecular fingerprinting is combined with localized surface plasmons (LSPs) on metal surfaces to achieve high sensitivity. Silver and gold colloids are among the most common nanostructured substrates used in SERS, but since protein-rich samples such as serum or plasma can hinder the SERS effect due to protein–substrate interactions, they often require a deproteinization step. Moreover, SERS methods based on metal colloids often suffer from a poor reproducibility. Here, we propose a paper-based SERS sampling method in which unprocessed human serum samples are first soaked on paper strips (0.4 × 2 cm2), and then mixed with colloidal silver nanoparticles by centrifugation to obtain a Centrifugal Silver Plasmonic Paper (CSPP). The CSPP methodology has the potential to become a promising tool in bioanalytical SERS applications: it uses common colloidal substrates but without the need for sample deproteinization, while having a good reproducibility both in terms of overall spectral shape (r > 0.96) and absolute intensity (RSD < 10%). Moreover, this methodology allows SERS analysis more than one month after serum collection on the paper strip, facilitating storage and handling of clinical samples (including shipping from clinical sites to labs).

Signaling via the FLP-14/FRPR-19 neuropeptide pathway sustains nociceptive response to repeated noxious stimuli in C. elegans

In order to thrive in constantly changing environments, animals must adaptively respond to threatening events. Noxious stimuli are not only processed according to their absolute intensity, but also to their context. Adaptation processes can cause animals to habituate at different rates and degrees in response to permanent or repeated stimuli. Here, we used a forward genetic approach in Caenorhabditis elegans to identify a neuropeptidergic pathway, essential to prevent fast habituation and maintain robust withdrawal responses to repeated noxious stimuli. This pathway involves the FRPR-19A and FRPR-19B G-protein coupled receptor isoforms produced from the frpr-19 gene by alternative splicing. Loss or overexpression of each or both isoforms can impair withdrawal responses caused by the optogenetic activation of the polymodal FLP nociceptor neuron. Furthermore, we identified FLP-8 and FLP-14 as FRPR-19 ligands in vitro. flp-14, but not flp-8, was essential to promote withdrawal response and is part of the same genetic pathway as frpr-19 in vivo. Expression and cell-specific rescue analyses suggest that FRPR-19 acts both in the FLP nociceptive neurons and downstream interneurons, whereas FLP-14 acts from interneurons. Importantly, genetic impairment of the FLP-14/FRPR-19 pathway accelerated the habituation to repeated FLP-specific optogenetic activation, as well as to repeated noxious heat and harsh touch stimuli. Collectively, our data suggest that well-adjusted neuromodulation via the FLP-14/FRPR-19 pathway contributes to promote nociceptive signals in C. elegans and counteracts habituation processes that otherwise tend to rapidly reduce aversive responses to repeated noxious stimuli.

Metabolism- and sex-dependent critical WBGT limits at rest and during exercise in the heat

Critical environmental limits are environmental thresholds above which heat gain exceeds heat loss and body core temperature (Tc) cannot be maintained at equilibrium. Those limits can be represented as critical wet-bulb globe temperature (WBGTcrit), a validated index that represents the overall thermal environment. Little is known about WBGTcrit at rest and during low-to-moderate intensity exercise, or sex differences in WBGTcrit, in unacclimated young adults. The following hypotheses were tested: (1) WBGTcrit progressively decreases as metabolic heat production (Mnet) increases, (2) no sex differences in WBGTcrit occur at rest, and (3) WBGTcrit is lower during absolute-intensity exercise but higher at relative intensities in women compared to men. Thirty-six participants (19M/17W; 23±4 yr) were tested at rest, during light, absolute-intensity exercise (10 W), or during moderate, relative-intensity exercise (30% V̇O2max) in an environmental chamber. Dry-bulb temperature was clamped as relative humidity or ambient water vapor pressure was increased until an upward inflection was observed in Tc (rectal or esophageal temperature). Sex-aggregated WBGTcrit was lower during 10 W (32.9±1.7°C, P<0.0001) and 30% V̇O2max (31.6±1.1°C, P<0.0001) exercise vs. rest (35.3±0.8°C), and lower at 30% V̇O2max vs. 10 W (P=0.01). WBGTcrit was similar between sexes at rest (35.6±0.8°C vs. 35.0±0.8°C, P=0.83), but lower during 10 W (31.9±1.7°C vs. 34.1±0.3°C, P<0 .01) and higher during 30% V̇O2max (32.4±0.8°C vs. 30.8±0.9°C, P=0.03) exercise in women vs. men. These findings suggest that WBGTcrit decreases as Mnet increases, no sex differences occur in WBGTcrit at rest, and sex differences in WBGTcrit during exercise depend upon absolute vs. relative intensities.

Perfusion Parameters in Near-Infrared Fluorescence Imaging with Indocyanine Green: A Systematic Review of the Literature

(1) Background: Near-infrared fluorescence imaging is a technique capable of assessing tissue perfusion and has been adopted in various fields including plastic surgery, vascular surgery, coronary arterial disease, and gastrointestinal surgery. While the usefulness of this technique has been broadly explored, there is a large variety in the calculation of perfusion parameters. In this systematic review, we aim to provide a detailed overview of current perfusion parameters, and determine the perfusion parameters with the most potential for application in near-infrared fluorescence imaging. (2) Methods: A comprehensive search of the literature was performed in Pubmed, Embase, Medline, and Cochrane Review. We included all clinical studies referencing near-infrared perfusion parameters. (3) Results: A total of 1511 articles were found, of which, 113 were suitable for review, with a final selection of 59 articles. Near-infrared fluorescence imaging parameters are heterogeneous in their correlation to perfusion. Time-related parameters appear superior to absolute intensity parameters in a clinical setting. (4) Conclusions: This literature review demonstrates the variety of parameters selected for the quantification of perfusion in near-infrared fluorescence imaging.

Low Geomagnetic Field Paleointensity on the Permian–Triassic Boundary from Study of the Kuznetsk Basin Traps (Southern Siberia)

—Here we report the first data on the absolute intensity value of the geomagnetic field on the Permian–Triassic boundary from basalts of the Kuznetsk basin. The latter are considered as one of the manifestations of the initial stage of trap magmatism during the formation of the Siberian large igneous province. The good preservation of information on the ancient geomagnetic field in the Mal’tsevskaya Formation basalts is due to the presence of small single domain and pseudo-single domain grains of primary magmatic titanomagnetite in the groundmass. The paleointensity values obtained following the Thellier-Coe method correspond to the generally accepted criteria of reliability and indicate that the geomagnetic field intensity during the formation of the Kuznetsk basin traps on the Permian–Triassic boundary was almost an order of magnitude lower than the present-day one. Moreover, the mean values of the virtual dipole moment for the Kozhukhta and the Vlasov units in the lower and middle Mal’tsevskaya Formation ((1.9 ± 0.6) · 1022 A · m2 and (1.1 ± 0.7) · 1022 A · m2, respectively) are in good alignment with determinations of the paleointensity during the accumulation of the Ivakinsky Formation of the Norilsk Region in the Siberian province, which confirms the accuracy of traditional regional correlations.

Laser–Material Interactions of High-Quality Ultrashort Pulsed Vector Vortex Beams

Diffractive multi-beams based on 1 × 5 and 2 × 2 binary Dammann gratings applied to a spatial light modulator (SLM) combined with a nanostructured S-wave plate have been used to generate uniform multiple cylindrical vector beams with radial and azimuthal polarizations. The vector quality factor (concurrence) of the single vector vortex beam was found to be C = 0.95 ± 0.02, hence showing a high degree of vector purity. The multi-beams have been used to ablate polished metal samples (Ti-6Al-4V) with laser-induced periodic surface structures (LIPSS), which confirm the polarization states unambiguously. The measured ablation thresholds of the ring mode radial and azimuthal polarizations are close to those of a Gaussian mode when allowance is made for the expected absolute intensity distribution of a ring beam generated from a Gaussian. In addition, ring mode vortex beams with varying orbital angular momentum (OAM) exhibit the same ablation threshold on titanium alloy. Beam scanning with ring modes for surface LIPSS formation can increase micro-structuring throughput by optimizing fluence over a larger effective beam diameter. The comparison of each machined spot was analysed with a machine learning method—cosine similarity—which confirmed the degree of spatial uniformity achieved, reaching cosθ > 0.96 and 0.92 for the 1 × 5 and 2 × 2 arrays, respectively. Scanning electron microscopy (SEM), optical microscopy and white light surface profiling were used to characterize and quantify the effects of surface modification.

Intensity Paradox—Low-Fit People Are Physically Most Active in Terms of Their Fitness

Depending on their cardiorespiratory fitness (CRF), people may perceive the exertion of incident physical activity (PA) differently. Therefore, the use of relative intensity thresholds based on individual fitness have been proposed to evaluate the accumulation of PA at different intensity levels. A subsample of the FinFit2017-study, 1952 adults (803 men and 1149 women) aged 20–69 years, participated in this study. Their maximal oxygen uptake (VO2max) was predicted with a 6 min walk test, and they were instructed to wear a triaxial hip-worn accelerometer for one week. The participants were divided into CRF tertiles by five age groups and sex. Raw acceleration data were analyzed with the mean amplitude deviation method in 6 s epochs. Additionally, the data were smoothed with 1 min and 6 min exponential moving averages. The absolute intensity threshold for moderate activity was 3.0 metabolic equivalent (MET) and for vigorous 6.0 MET. Correspondingly, the relative thresholds were 40% and 60% of the oxygen uptake reserve. Participants in the lowest CRF tertile were the most active with relative thresholds, and participants in the highest CRF tertile were the most active with absolute thresholds. High-fit people easily reached the absolute thresholds, while people in the lowest CRF tertile had to utilize most of their aerobic capacity on a daily basis simply to keep up with their daily chores or peers.

Track Dependence of Tropical Cyclone Intensity Forecast Errors in the COAMPS-TC Model

This study examines the dependence of tropical cyclone (TC) intensity forecast errors on track forecast errors in the Coupled Ocean/Atmosphere Mesoscale Prediction System for Tropical Cyclones (COAMPS-TC) model. Using real-time forecasts and retrospective experiments during 2015-2018, verification of TC intensity errors conditioned on different 5-day track error thresholds shows that reducing the 5-day track errors by 50-70% can help reduce the absolute intensity errors by 18-20% in the 2018 version of the COAMPS-TC model. Such impacts of track errors on the TC intensity errors are most persistent at 4-5 day lead times in all three major ocean basins, indicating a significant control of global models on the forecast skill of the COAMPS-TC model. It is of interest to find, however, that lowering the 5-day track errors below 80 nm does not reduce TC absolute intensity errors further. Instead, the 4-5 day intensity errors appear to be saturated at around 10-12 kt for cases with small track errors, thus suggesting the existence of some inherent intensity errors in regional models.Additional idealized simulations under a perfect model scenario reveal that the COAMPS-TC model possesses an intrinsic intensity variation at the TC mature stage in the range of 4-5 kt, regardless of the large-scale environment. Such intrinsic intensity variability in the COAMPS-TC model highlights the importance of potential chaotic TC dynamics, rather than model deficiencies, in determining TC intensity errors at 4-5 day lead times. These results indicate a fundamental limit in the improvement of TC intensity forecasts by numerical models that one should consider in future model development and evaluation.

Aerobic Training Modulates the Increase in Plasma Concentrations of Cytokines in response to a Session of Exercise

Acute physical exercise can modulate immune function. For example, acute exercise is known to increase the circulating concentration of cytokines. Exercise is also known to modulate immune function chronically. It is not known whether exercise training can result in training of the immune system. Here, we investigated the effects of six weeks of aerobic training on cytokine responses induced by acute exercise until fatigue. Twelve healthy men performed a fatiguing exercise at the anaerobic threshold (AT) intensity. After the training period, the participants performed another bout of acute exercise at the same duration and intensity of the pretraining situation. The analysis was made at the beginning, end, and at 10, 30, and 60 minutes during the recovery period. Training at AT induced a gain of 11.2% of exercise capacity. Before training, a single bout of acute exercise induced a significant increase in plasma levels of cytokines, including IL-6, TNF-α, sTNFR1, IL-10, CXCL10, BDNF, leptin, resistin, and adiponectin. After six weeks of aerobic training, levels of IL-6, sTNFR1, BDNF, and leptin increased to a lesser extent after an acute bout exercise at the same absolute intensity as the pretraining period. Responses to the same relative exercise intensity were similar to those observed before exercise. These results show that aerobic training is associated with training of acute immune responses to acute exercise until fatigue.