The flow of an electrically conducting fluid in a thin disc under the action of an azimuthal Lorentz force is studied experimentally. At small forcing, the Lorentz force is balanced by either ...viscosity or inertia, yielding quasi-Keplerian velocity profiles. For very large current I and moderate magnetic field B, we observe a new regime, fully turbulent, which exhibits large fluctuations and a Keplerian mean rotation profile $\varOmega \sim {\sqrt {IB}}/{r^{3/2}}$, where r is the distance from the axis. In this turbulent regime, the dynamics is typical of thin layer turbulence, characterized by a direct cascade of energy towards the small scales and an inverse cascade to large scales. Finally, at very large magnetic field, this turbulent flow bifurcates to a quasi-bidimensional turbulent flow involving the formation of a large scale condensate in the horizontal plane. These results are well understood as resulting from an instability of the Bödewadt–Hartmann layers at large Reynolds number and discussed in the framework of similar astrophysical flows.
With the prevalence of obesity rapidly increasing worldwide, understanding the processes leading to excessive eating behavior becomes increasingly important. Considering the widely recognized crucial ...role of reward processes in food intake, we examined the white matter wiring and integrity of the anatomical reward network in obesity. Anatomical wiring of the reward network was reconstructed derived from diffusion weighted imaging in 31 obese participants and 32 normal-weight participants. Network wiring was compared in terms of the white matter volume as well as in terms of white matter microstructure, revealing lower number of streamlines and lower fiber integrity within the reward network in obese subjects. Specifically, the orbitofrontal cortex and striatum nuclei including accumbens, caudate and putamen showed lower strength and network clustering in the obesity group as compared to healthy controls. Our results provide evidence for obesity-related disruptions of global and local anatomical connectivity of the reward circuitry in regions that are key in the reinforcing mechanisms of eating-behavior processes.
•This study analyzes the structural connectivity of the reward system in obesity.•The highly homogeneous sample consists of metabolically healthy young participants.•Obesity group shows lower volume and integrity in the reward system pathways.•Results evidence affected reward system connectivity in obesity.•Results suggest a neuroanatomical substrate for reward related to eating behavior.
Glacial dropstones Ziegler, A. F.; Smith, C. R.; Edwards, K. F. ...
Marine ecology. Progress series (Halstenbek),
11/2017, Letnik:
583
Journal Article
Recenzirano
Odprti dostop
The West Antarctic Peninsula (WAP) margin is dominated by glaciomarine fjords and has experienced rapid climate warming in recent de cades. Glacial calving along the peninsula delivers ice-rafted ...debris (e.g. dropstones) to heavily sedimented fjord basins and the open continental shelf. Dropstones provide hard substrate, increase habitat heterogeneity, and may function as island habitats surrounded by mud. We used seafloor photographic transects to evaluate the distribution and community structure of Antarctic hard-substrate megafauna and the role of dropstones as island habitats in 3 WAP fjords and at 3 nearby shelf stations. Several lines of evidence indicate that dropstones function as island habitats; their communities adhere to principles of island biogeography theory with (1) a positive correlation between dropstone size and species richness, (2) an increase in the proportion of colonized dropstones with increasing dropstone size, and (3) a species−area scaling exponent consistent with island habitats measured globally. Previous work on the soft-sediment megafauna of this region found strong differences in community composition between fjord and shelf sites, whereas we found that dropstone communities differed within sites at small scales (1 km and smaller). We identified 73 megafaunal morphotypes associated with dropstones, 29 of which were not previously documented in the soft-sediment mega - fauna. While dropstones constituted >1% of the total seafloor area surveyed, they contributed 20% of the overall species richness of WAP megabenthos at depths of 437–724 m. WAP dropstone communities adhere to key principles of island biogeography theory, contribute environmental heterogeneity, and increase biodiversity in the WAP region.
Obesity is a health problem that has become a major focus of attention in recent years. There is growing evidence of an association between obesity and differences in reward processing. However, it ...is not known at present whether these differences are linked exclusively to food, or whether they can be detected in other rewarding stimuli. We compared responses to food, rewarding non-food and neutral pictures in 18 young adults with obesity and 19 normal-weight subjects using independent component analysis. Both groups modulated task-related activity in a plausible way. However, in response to both food and non-food rewarding stimuli, participants with obesity showed weaker connectivity in a network involving activation of frontal and occipital areas and deactivation of the posterior part of the default mode network. In addition, obesity was related with weaker activation of the default mode network and deactivation of frontal and occipital areas while viewing neutral stimuli. Together, our findings suggest that obesity is related to a different allocation of cognitive resources in a fronto-occipital network and in the default mode network.
► We compared participants with obesity and normal-weight controls on a reward task. ► Both groups modulated task-related activity in a plausible way. ► Obesity was associated with differences in the integration of resources.
Complementary feeding plays a crucial role in the development of infants and toddlers and studies suggest benefits specific to the introduction of food textures.
Evaluate the recommendations given to ...parents, their practices, and their attitudes towards the introduction of food textures during complementary feeding in France.
This was a cross-sectional pilot study conducted in 2013. One hundred and eighty-one parents with at least one child aged 6–36 months living in France completed an ad hoc questionnaire.
Eighty-eight percent of the parents surveyed received oral information on complementary feeding, but only 46% received such information on the introduction of food textures. Pediatricians were the most frequently listed source of oral information on complementary feeding. More than half the parents also looked for additional information in books and on the internet. While oral recommendations matched parents’ practices, they seemed to occur at a later age compared to infants’ physiological ability to handle new textures. The quality of information on food texture advice available in paper and electronic formats evaluated using a 4-point scale was found to be limited. Introducing new food texture was spontaneously reported as the most common difficulty in complementary feeding (16%). Fear of choking when first introducing food pieces was reported by 54% of the parents.
The parents’ lack of information on the introduction of food textures, as well as their fear that their child may choke, should encourage providing new recommendations in France.
Patients living with and beyond breast cancer frequently exhibit several side effects that can impact quality of life and physical functioning way beyond diagnosis and cancer therapies. Traditional ...on-land exercise has shown to be effective in reducing several symptoms of BC but little is known about the role of water-based exercise in improving physical and psychological well-being.
To compare land- vs. water-based exercise training for BC survivors to improve Health-Related Quality of Life (HRQoL), cancer-related fatigue (CRF), physical functioning, body composition and physical activity in patients with BC.
A randomised, parallel group (1:1) controlled trial was conducted between 2020 and 2022. Patients were randomly allocated to complete a similar exercise training twice weekly during 12 weeks either on land (LG) using traditional gym equipment or in a swimming pool (WG) using body-weight exercises and water-suitable accessories. Both groups were supervised and monitored by an experienced physiotherapist. Main outcome was HRQoL (EORTC QLQ C30 and B23 module) and CRF measured with the Piper Scale. Secondary variables included functional capacity with the 6 Minutes Walking Test (6MWT), upper and lower body strength (handgrip strength and 30″ Sit-to-Stand (STS) test), body composition and objectively measured physical activity.
28 patients were assessed and randomised during the study period. One patient did not receive the allocated intervention due to skin issues and one patient was dropped out during the intervention. A significant effect of time was found for both symptom severity (F(
,
) = 6.46, p = 0.003) and overall functioning (F
= 5.215, p =0 .013) but no interaction was found between group and time. No effects were reported for CRF. Similar findings were reported for functional capacity (time effect F
= 16.818, p < 0.001) and lower body strength (time effect F
= 15.120, p < 0.001) as well as fat mass (time effect F
= 4.38, p = 0.017). Notably, a significant time per group interaction was reported for physical activity (F
= 6.349, p =0.003) with patients in the WG significantly improving PA levels over time while patients in the LG exhibited a marked decreased.
Exercise training either in water or on land can decrease symptom severity and improve functionality and body composition. Water-based training seems more effecting than land-based exercise to improve physical activity patterns over time.
From January 2011 to December 2013, we constructed a comprehensive pCO2 data set based on voluntary observing ship (VOS) measurements in the western English Channel (WEC). We subsequently estimated ...surface pCO2 and air–sea CO2 fluxes in northwestern European continental shelf waters using multiple linear regressions (MLRs) from remotely sensed sea surface temperature (SST), chlorophyll a concentration (Chl a), wind speed (WND), photosynthetically active radiation (PAR) and modeled mixed layer depth (MLD). We developed specific MLRs for the seasonally stratified northern WEC (nWEC) and the permanently well-mixed southern WEC (sWEC) and calculated surface pCO2 with uncertainties of 17 and 16 µatm, respectively. We extrapolated the relationships obtained for the WEC based on the 2011–2013 data set (1) temporally over a decade and (2) spatially in the adjacent Celtic and Irish seas (CS and IS), two regions which exhibit hydrographical and biogeochemical characteristics similar to those of WEC waters. We validated these extrapolations with pCO2 data from the SOCAT and LDEO databases and obtained good agreement between modeled and observed data. On an annual scale, seasonally stratified systems acted as a sink of CO2 from the atmosphere of -0.6 ± 0.3, -0.9 ± 0.3 and -0.5 ± 0.3 mol C m-2 yr-1 in the northern Celtic Sea, southern Celtic sea and nWEC, respectively, whereas permanently well-mixed systems acted as source of CO2 to the atmosphere of 0.2 ± 0.2 and 0.3 ± 0.2 mol C m-2 yr-1 in the sWEC and IS, respectively. Air–sea CO2 fluxes showed important inter-annual variability resulting in significant differences in the intensity and/or direction of annual fluxes. We scaled the mean annual fluxes over these provinces for the last decade and obtained the first annual average uptake of -1.11 ± 0.32 Tg C yr-1 for this part of the northwestern European continental shelf. Our study showed that combining VOS data with satellite observations can be a powerful tool to estimate and extrapolate air–sea CO2 fluxes in sparsely sampled area.
Anti-silencing function 1 (ASF1) is an evolutionarily conserved histone H3-H4 chaperone involved in the assembly/disassembly of nucleosome and histone modification. Two paralogous genes, Asf1a and ...Asf1b, exist in the mouse genome. Asf1a is ubiquitously expressed and its loss causes embryonic lethality. Conversely, Asf1b expression is more restricted and has been less studied. To determine the in vivo function of Asf1b, we generated a Asf1b-deficient mouse line (Asf1b(GT(ROSA-βgeo)437)) in which expression of the lacZ reporter gene is driven by the Asf1b promoter. Analysis of β-galactosidase activity at early embryonic stages indicated a correlation between Asf1b expression and cell differentiation potential. In the gonads of both male and female, Asf1b expression was specifically detected in the germ cell lineage with a peak expression correlated with meiosis. The viability of Asf1b-null mice suggests that Asf1b is dispensable for mouse development. However, these mice showed reduced reproductive capacity compared with wild-type controls. We present evidence that the timing of meiotic entry and the subsequent gonad development are affected more severely in Asf1b-null female mice than in male mice. In female mice, in addition to subfertility related to altered gamete formation, variable defects compromising the development and/or survival of their offspring were also observed. Altogether, our data indicate the importance of Asf1b expression at the time of meiotic entry, suggesting that chromatin modifications may play a central role in this process.
Question Correlational evidence in monkeys has reported increased synchrony of high-beta (22–34 Hz) cortical oscillations between frontal and parietal attentional regions during visual tasks engaging ...an endogenous capture of attention (Buschmann and Miller, Science, 2007). However, these results lack causality. We aim to demonstrate that this frequency specific intrahemispheric synchronization is causally linked to the modulation of visual performance. Methods We recorded EEG signals in human participants ( n = 14) who performed a conscious visual detection task while we manipulated cortical high-beta rhythms with brief rhythmic (30 Hz, 4 pulses) or random bursts of rhythmic Transcranial Magnetic Stimulation (rTMS) delivered to the right Frontal Eye Field (FEF). Participants had to report (yes/no) if he had seen the target (an individually titrated low contrast gabor at 50% detection levels) and if ‘yes’, where it had appeared (left/right of the fixation cross). Individual perceptual sensitivity (d′ ) was determined using signal detection theory. From the EEG signal, a classical measure of phase-synchrony (evaluating the stability of the phase-relationship between 2 signals) was calculated between the electrode closest to the TMS coil position (FC2) and all other scalp electrodes. To rule-out artificial enhancement of synchrony between pairs of neighbouring scalp electrodes, zero-phase synchronization was not considered. Results We report, in the rhythmic TMS condition (compared to the random TMS control), an increase of inter-regional synchronization in the high-beta band (25–35 Hz) between the area stimulated (right FEF) and a group of parietal electrodes, as well as an increase of local inter-trial coherence in the same frequency band over parietal electrodes. Behaviorally, conscious visual detection was improved for left visual targets (contralateral to the stimulation) in the rhythmic but not random TMS condition. Conclusion Our results show that human high-beta inter-regional synchrony can be manipulated non-invasively and that high-beta oscillatory activity across the right dorsal fronto-parietal attention network causally contributes to the facilitation of conscious visual detection, suggesting potential applications of rhythmic non-invasive brain stimulation for the restoration of impaired visual behaviors.
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