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The secret ingredient
While working at her grandmother's Madison, Wisconsin, teashop, fourteen-year-old Annie hears of a scone cook-off, for which the prize is an all-expense paid trip to London for tea, and enlists Genna and Zoe to help her win. Includes proverbs, quotations, and brief stories about tea, as well as recipes.
Book
Paired personal interaction reveals objective differences between pushing and holding isometric muscle action
In sports and movement sciences isometric muscle function is usually measured by pushing against a stable resistance. However, subjectively one can hold or push isometrically. Several investigations suggest a distinction of those forms. The aim of this study was to investigate whether these two forms of isometric muscle action can be distinguished by objective parameters in an interpersonal setting. 20 subjects were grouped in 10 same sex pairs, in which one partner should perform the pushing isometric muscle action (PIMA) and the other partner executed the holding isometric muscle action (HIMA). The partners had contact at the distal forearms via an interface, which included a strain gauge and an acceleration sensor. The mechanical oscillations of the triceps brachii (MMGtri) muscle, its tendon (MTGtri) and the abdominal muscle (MMGobl) were recorded by a piezoelectric-sensor-based measurement system. Each partner performed three 15s (80% MVIC) and two fatiguing trials (90% MVIC) during PIMA and HIMA, respectively. Parameters to compare PIMA and HIMA were the mean frequency, the normalized mean amplitude, the amplitude variation, the power in the frequency range of 8 to 15 Hz, a special power-frequency ratio and the number of task failures during HIMA or PIMA (partner who quit the task). A “HIMA failure” occurred in 85% of trials ( p < 0.001). No significant differences between PIMA and HIMA were found for the mean frequency and normalized amplitude. The MMGobl showed significantly higher values of amplitude variation (15s: p = 0.013; fatiguing: p = 0.007) and of power-frequency-ratio (15s: p = 0.040; fatiguing: p = 0.002) during HIMA and a higher power in the range of 8 to 15 Hz during PIMA (15s: p = 0.001; fatiguing: p = 0.011). MMGtri and MTGtri showed no significant differences. Based on the findings it is suggested that a holding and a pushing isometric muscle action can be distinguished objectively, whereby a more complex neural control is assumed for HIMA.
Journal Article
Littler women : a modern retelling
During one year, Meg, Jo, Beth, and Amy March, aged nine to thirteen, get to know their neighbors the Lawrences, attend school dances and sleepovers, have first crushes, and grow closer despite their differences.
BOOK
Helium Depletion in Escaping Atmospheres of Sub-Neptunes: A Signature of Primary-to-secondary Transition
Short-period sub-Neptunes are common in extrasolar systems. These sub-Neptunes are generally thought to have primary atmospheres of protoplanetary-disk gas origin. However, atmospheric escape followed by degassing from their interiors can lead to the transition to secondary atmospheres depleted in gases less soluble in magma, such as helium. These primary and secondary atmospheres can potentially be distinguished from observations of escaping hydrogen and helium. This study aims to elucidate the impact of the primary-secondary transition on the atmospheric compositions of short-period sub-Neptunes. We simulate their evolution with atmospheric escape driven by stellar X-ray and extreme ultraviolet irradiation and degassing of hydrogen, helium, and water from their rocky interiors, with a 1D structure model. We show that the transition takes place for low-mass, close-in planets that experience extensive atmospheric escape. These planets show the depletion of helium and enrichment of water in their atmospheres because of their low and high abundances in the planetary interiors, respectively. A compilation of our parameter survey (the orbital period, planetary mass, envelope mass, and mantle FeO content) shows a correlation between the planet radius and the helium escape rate. We suggest that the transition from primary to secondary atmospheres may serve as an explanation for helium non-detection for relatively small (≲2.5 R⊕) exoplanets.
Journal Article
Magma oceans as a critical stage in the tectonic development of rocky planets
Magma oceans are a common result of the high degree of heating that occurs during planet formation. It is thought that almost all of the large rocky bodies in the Solar System went through at least one magma ocean phase. In this paper, we review some of the ways in which magma ocean models for the Earth, Moon and Mars match present-day observations of mantle reservoirs, internal structure and primordial crusts, and then we present new calculations for the oxidation state of the mantle produced during the magma ocean phase. The crystallization of magma oceans probably leads to a massive mantle overturn that may set up a stably stratified mantle. This may lead to significant delays or total prevention of plate tectonics on some planets. We review recent models that may help alleviate the mantle stability issue and lead to earlier onset of plate tectonics.
This article is part of a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.
Journal Article
Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b
Most known terrestrial planets orbit small stars with radii less than 60 per cent of that of the Sun
1
,
2
. Theoretical models predict that these planets are more vulnerable to atmospheric loss than their counterparts orbiting Sun-like stars
3
–
6
. To determine whether a thick atmosphere has survived on a small planet, one approach is to search for signatures of atmospheric heat redistribution in its thermal phase curve
7
–
10
. Previous phase curve observations of the super-Earth 55 Cancri e (1.9 Earth radii) showed that its peak brightness is offset from the substellar point (latitude and longitude of 0 degrees)—possibly indicative of atmospheric circulation
11
. Here we report a phase curve measurement for the smaller, cooler exoplanet LHS 3844b, a 1.3-Earth-radii world in an 11-hour orbit around the small nearby star LHS 3844. The observed phase variation is symmetric and has a large amplitude, implying a dayside brightness temperature of 1,040 ± 40 kelvin and a nightside temperature consistent with zero kelvin (at one standard deviation). Thick atmospheres with surface pressures above 10 bar are ruled out by the data (at three standard deviations), and less-massive atmospheres are susceptible to erosion by stellar wind. The data are well fitted by a bare-rock model with a low Bond albedo (lower than 0.2 at two standard deviations). These results support theoretical predictions that hot terrestrial planets orbiting small stars may not retain substantial atmospheres.
Phase curve measurements for the small (1.3 Earth radii) terrestrial exoplanet LHS 3844b show absence of a thick atmosphere, in agreement with theoretical predictions.
Journal Article
Disgusting odours affect the characteristics of the Adaptive Force in contrast to neutral and pleasant odours
The olfactomotor system is especially investigated by examining the sniffing in reaction to olfactory stimuli. The motor output of respiratory-independent muscles was seldomly considered regarding possible influences of smells. The Adaptive Force (AF) characterizes the capability of the neuromuscular system to adapt to external forces in a holding manner and was suggested to be more vulnerable to possible interfering stimuli due to the underlying complex control processes. The aim of this pilot study was to measure the effects of olfactory inputs on the AF of the hip and elbow flexors, respectively. The AF of 10 subjects was examined manually by experienced testers while smelling at sniffing sticks with neutral, pleasant or disgusting odours. The reaction force and the limb position were recorded by a handheld device. The results show, inter alia, a significantly lower maximal isometric AF and a significantly higher AF at the onset of oscillations by perceiving disgusting odours compared to pleasant or neutral odours (p < 0.001). The adaptive holding capacity seems to reflect the functionality of the neuromuscular control, which can be impaired by disgusting olfactory inputs. An undisturbed functioning neuromuscular system appears to be characterized by a proper length tension control and by an earlier onset of mutual oscillations during an external force increase. This highlights the strong connection of olfaction and motor control also regarding respiratory-independent muscles.
Journal Article
The Effect of Tidal Heating and Volatile Budgets on the Outgassed Atmosphere of 55 Cancri e
55 Cancri e (55 Cnc e) is an ∼8 Gyr rocky world (1.95 R⊕ and 8.8 M⊕) orbiting a K-type star. JWST observations suggest a carbon-dominated atmosphere (CO2 and CO) over a global magma ocean (>3000 K). We suggest that any CO2-dominated atmosphere, with trace amounts of H2O and O2, likely arises from outgassing of its initial volatile reservoir. As solidification drives the magma ocean and atmosphere away from solution equilibrium, tidal and greenhouse heating can prolong outgassing. Early atmosphere outgassing reflects rapid degassing of the volatile-saturated melt during postformation cooling. Without tidal heating, an initial 5 wt% water mass fraction ( FH2O ) or 3 wt% CO2 mass fraction ( FCO2 ) can sustain outgassing for at least ∼10 Myr. With both at 10 wt%, greenhouse warming alone can prolong outgassing up to ∼30 Myr. Our model shows that tidal heating can reduce the volatile threshold required to maintain a high surface temperature (∼3200 K at e = 0.005) and delay outgassing of additional volatiles to the present day. However, higher tidal heating presents a trade-off between prolonging tenuous outgassing and enlarging the overall size of the secondary atmosphere. Tidally enhanced outgassing may produce minor pressure variations that could contribute to the observed phase-curve variability. Additionally, our model shows that tidal heating strongly controls outgassing in the planet’s young-to-midlife stage, then shifts toward a volatile inventory dependence at mature ages. Using 55 Cnc e, we present a framework to prioritize atmosphere detections on rocky ultrashort period magma ocean planets, linking age-dependent tidal heating and volatile inventory to the formation and size of secondary atmospheres.
Journal Article
Adaptive Force of hamstring muscles is reduced in patients with knee osteoarthritis compared to asymptomatic controls
Background
Quadriceps strength deficits are known for patients with knee osteoarthritis (OA), whereas findings on hamstrings are less clear. The Adaptive Force (AF) as a special neuromuscular function has never been investigated in OA before. The maximal adaptive holding capacity (max. isometric AF; AFiso
max
) has been considered to be especially vulnerable to disruptive stimuli (e.g., nociception). It was hypothesized that affected limbs of OA patients would show clear deficits in AFiso
max
.
Methods
AF parameters and the maximal voluntary isometric contraction (MVIC) of hamstrings were assessed bilaterally comparing 20 patients with knee OA (ART) vs. controls (CON). AF was measured by a pneumatically driven device. Participants were instructed to maintain a static position despite an increasing load of the device. After reaching AFiso
max
, the hamstrings merged into eccentric action whereby the force increased further to the maximum (AF
max
). MVIC was recorded before and after AF trials. Mixed ANOVA was used to identify differences between and within ART and CON (comparing 1st and 2nd measured sides).
Results
AFiso
max
and the torque development per degree of yielding were significantly lower only for the more affected side of ART vs. CON (
p
≤ 0.001). The percentage difference of AFiso
max
amounted to − 40%. For the less affected side it was − 24% (
p
= 0.219). MVIC and AF
max
were significantly lower for ART vs. CON for both sides (
p
≤ 0.001). Differences of MVIC between ART vs. CON amounted to − 27% for the more, and − 30% for the less affected side; for AF
max
it was − 34% and − 32%, respectively.
Conclusion
The results suggest that strength deficits of hamstrings are present in patients with knee OA possibly attributable to nociception, generally lower physical activity/relief of lower extremities or fear-avoidance. However, the more affected side of OA patients seems to show further specific impairments regarding neuromuscular control reflected by the significantly reduced adaptive holding capacity and torque development during adaptive eccentric action. It is assumed that those parameters could reflect possible inhibitory nociceptive effects more sensitive than maximal strengths as MVIC and AF
max
. Their role should be further investigated to get more specific insights into these aspects of neuromuscular control in OA patients. The approach is relevant for diagnostics also in terms of severity and prevention.
Journal Article
Manual Muscle Testing—Force Profiles and Their Reproducibility
The manual muscle test (MMT) is a flexible diagnostic tool, which is used in many disciplines, applied in several ways. The main problem is the subjectivity of the test. The MMT in the version of a “break test” depends on the tester’s force rise and the patient’s ability to resist the applied force. As a first step, the investigation of the reproducibility of the testers’ force profile is required for valid application. The study examined the force profiles of n = 29 testers (n = 9 experiences (Exp), n = 8 little experienced (LitExp), n = 12 beginners (Beg)). The testers performed 10 MMTs according to the test of hip flexors, but against a fixed leg to exclude the patient’s reaction. A handheld device recorded the temporal course of the applied force. The results show significant differences between Exp and Beg concerning the starting force (padj = 0.029), the ratio of starting to maximum force (padj = 0.005) and the normalized mean Euclidean distances between the 10 trials (padj = 0.015). The slope is significantly higher in Exp vs. LitExp (p = 0.006) and Beg (p = 0.005). The results also indicate that experienced testers show inter-tester differences and partly even a low intra-tester reproducibility. This highlights the necessity of an objective MMT-assessment. Furthermore, an agreement on a standardized force profile is required. A suggestion for this is given.
Journal Article