Medical Risks and Capabilities for Human Exploration Spaceflight

No abstract availabl

Pressurized Device for Mitigating Atrophy in Soleus During Long-Duration Spaceflight

A major concern with long duration spaceflight, skeletal muscle atrophy is most detrimental in lower limb musculature, particularly in muscles critical for proper gait, such as the soleus. The decline of muscle activation and the suppression of sensory input from plantar sole mechanoreceptors can add to the attenuation of skeletal muscle health during spaceflight. More specifically, inhibition of sensory input from sole receptors, such as with gravitational unloading, decreases selective activation, thereby negatively affecting muscle tone and inevitably resulting in lower limb atrophy. PURPOSE: To design, fabricate, and test a specialized boot with an insole that applies oscillating pneumatic pressure for set periods of time to augment neuromuscular activation of the soleus through the plantar sole\u27s mechanoreceptors, which may minimize atrophy of lower extremity muscles. METHODS: The custom boot was originally designed in three-dimensional modeling software (Solidworks Premium, Waltham, MA). Components of the boot included: a lightweight medical walking brace, Metro-ATmega circuit board, air pump and vacuum DC motor, force resistive sensor, and kPa sensor. The boot was programmed using C++ to allow the user to wear the boot for 20 minutes (oscillating continuously) at the start of every hour with an automatic timer for 6 hours per day. Surface electromyography (EMG) measured electrical activity in lower extremity muscles while wearing the boot. The location of all electrodes were determined according to the SENIAM project (Surface Electromyography for the Non-Invasive Assessment of Muscles): 1) for soleus, electrode placed at two-thirds of the line between the medial condyle of the femur to the medial malleolus; 2) for medial head of the gastrocnemius, electrode placed at one-third of the line between the head of the fibula and the heel; 3) for ground, electrode placed at the tibial tuberosity. Muscle activation of the gastrocnemius was measured to investigate any co-activation of nearby musculature on the posterior leg. RESULTS: Upon airbag inflation, the soleus exhibited the greatest amplitude (30 to 50 µV versus 5 to 15 µV) when the ankle attempted to plantarflex while maintaining a neutral position. When the airbags are inflated, the pressure output corresponds to approximately 111 kPa. When the airbags are deflated, the pressure output corresponds to approximately 66 kPa, creating a pressure difference of 45 kPa. During the 20 min runtime, the airbags take 3.3 sec to inflate and 3.0 sec to deflate, creating the oscillating effect. When fully charged, the battery can sustain one full, 6-hour session with each lasting 20 minutes. CONCLUSION: Pneumatic pressure integrated into a customized therapeutic walking boot may elicit neuromuscular activity in the lower extremity musculature, which indicates that the device may help in attenuating the negative neuromuscular adaptations in the soleus via afferent signaling

The influence of perceived stress on the human microbiome

Objective Microbial dysbiosis, a shift from commensal to pathogenic microbiota, is often associated with mental health and the gut&ndash;brain axis, where dysbiosis in the gut may be linked to dysfunction in the brain. Many studies focus on dysbiosis induced by clinical events or traumatic incidents; however, many professions in austere or demanding environments may encounter continuously compounded stressors. This study seeks to explore the relationship between microbial populations and stress, both perceived and biochemical. Results Eight individuals enrolled in the study to provide a longitudinal assessment of the impact of stress on gut health, with four individuals providing enough samples for analysis. Eleven core microbial genera were identified, although the relative abundance of these genera and other members of the microbial population shifted over time. Although our results indicate a potential relationship between perceived stress and microbial composition of the gut, no association with biochemical stress was observed. Increases in perceived stress seem to elucidate a change in potentially beneficial Bacteroides, with a loss in Firmicutes phyla. This shift occurred in multiple individuals, whereas using cortisol as a stress biomarker showed contradictory responses. These preliminary data provide a potential mechanism for gut monitoring, while identifying targets for downstream modulation. &nbsp;</p

Clinical Trials and Medical Care: Defining the Therapeutic Misconception

A key component of informed consent to participate in medical research includes understanding that research is not the same as treatment

Aerosol indirect effects

Aerosol indirect effects continue to constitute one of the most important uncertainties for anthropogenic climate perturbations. Within the international AEROCOM initiative, the representation of aerosol-cloud-radiation interactions in ten different general circulation models (GCMs) is evaluated using three satellite datasets. The focus is on stratiform liquid water clouds since most GCMs do not include ice nucleation effects, and none of the model explicitly parameterises aerosol effects on convective clouds. We compute statistical relationships between aerosol optical depth (tau a) and various cloud and radiation quantities in a manner that is consistent between the models and the satellite data. cloud droplet number concentration (N d) compares relatively well to the satellite data at least over the ocean. The relationship between (tau a) and liquid water path is simulated much too strongly by the models. This suggests that the implementation of the second aerosol indirect effect mainly in terms of an autoconversion parameterisation has to be revisited in the GCMs. A positive relationship between total cloud fraction (fcld) and tau a as found in the satellite data is simulated by the majority of the models, albeit less strongly than that in the satellite data in most of them. In a discussion of the hypotheses proposed in the literature to explain the satellite-derived strong fcld–tau a relationship, our results indicate that none can be identified as a unique explanation. Relationships similar to the ones found in satellite data between tau a and cloud top temperature or outgoing long-wave radiation (OLR) are simulated by only a few GCMs. The GCMs that simulate a negative OLR - tau a relationship show a strong positive correlation between tau a and fcld. The short-wave total aerosol radiative forcing as simulated by the GCMs is strongly influenced by the simulated anthropogenic fraction of tau a, and parameterisation assumptions such as a lower bound on Nd. Nevertheless, the strengths of the statistical relationships are good predictors for the aerosol forcings in the models. An estimate of the total short-wave aerosol forcing inferred from the combination of these predictors for the modelled forcings with the satellite-derived statistical relationships yields a global annual mean value of −1.5±0.5Wm−2. In an alternative approach, the radiative flux perturbation due to anthropogenic aerosols can be broken down into a component over the cloud-free portion of the globe (approximately the aerosol direct effect) and a component over the cloudy portion of the globe (approximately the aerosol indirect effect). An estimate obtained by scaling these simulated clearand cloudy-sky forcings with estimates of anthropogenic tau a and satellite-retrieved Nd–tau a regression slopes, respectively, yields a global, annual-mean aerosol direct effect estimate of −0.4±0.2Wm−2 and a cloudy-sky (aerosol indirect effect) estimate of −0.7±0.5Wm−2, with a total estimate of −1.2±0.4Wm−2

Erratum: “Searches for Gravitational Waves from Known Pulsars at Two Harmonics in 2015–2017 LIGO Data” (2019, ApJ, 879, 10)

Due to an error at the publisher, in the published article the number of pulsars presented in the paper is incorrect in multiple places throughout the text. Specifically, "222" pulsars should be "221." Additionally, the number of pulsars for which we have EM observations that fully overlap with O1 and O2 changes from "168" to "167." Elsewhere, in the machine-readable table of Table 1 and in Table 2, the row corresponding to pulsar J0952-0607 should be excised as well. Finally, in the caption for Table 2 the number of pulsars changes from "188" to "187.

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO’s second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h95%0=3.47×10−25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering

Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

[no abstract available