Therapeutic Prospects of Metabolically Active Brown Adipose Tissue in Humans

The world-wide obesity epidemic constitutes a severe threat to human health and wellbeing and poses a major challenge to health-care systems. Current therapeutic approaches, relying mainly on reduced energy intake and/or increased exercise energy expenditure, are generally of limited effectiveness. Previously believed to be present only in children, the existence of metabolically active brown adipose tissue (BAT) was recently demonstrated also in healthy human adults. The physiological role of BAT is to dissipate chemical energy, mainly from fatty acids, as heat to maintain body temperature in cold environments. Recent studies indicate that the activity of BAT is negatively correlated with overweight and obesity, findings that raise the exciting possibility of new and effective weight reduction therapies based on increased BAT energy expenditure, a process likely to be amenable to pharmacological intervention

Entropy bound for time reversal markers

Considering positive observables with specific symmetries under path reversal yields a bound for entropy production, in terms of the deviation of the observable mean from equilibrium, or, equivalently, in terms of the difference of the mean measured in forward and backward dynamics. It is fundamentally different than known relations such as the thermodynamic uncertainty relation. The bound is met exactly for a two state process. We further exemplify the relation for a trapped active Brownian particle. This relation is not limited to Markov chains or specific dynamics.Comment: 5 pages, 3 figure

High-performance designs for fiber-pigtailed quantum-light sources based on quantum dots in electrically-controlled circular Bragg gratings

We present a numerical investigation of directly fiber-coupled hybrid circular Bragg gratings (CBGs) featuring electrical control for operation in the application relevant wavelength regimes around 930 nm as well as the telecom O- and C-band. We use a surrogate model combined with a Bayesian optimization approach to perform numerical optimization of the device performance which takes into account robustness with respect to fabrication tolerances. The proposed high-performance designs combine hCBGs with a dielectric planarization and a transparent contact material, enabling >86% direct fiber coupling efficiency (up to >93% efficiency into NA 0.8) while exhibiting Purcell Factors >20. Especially the proposed designs for the telecom range prove robust and can sustain expected fiber efficiencies of more than $(82.2\pm4.1)^{+2.2}_{-5.5}$% and expected average Purcell Factors of up to $(23.2\pm2.3)^{+3.2}_{-3.0}$ assuming conservative fabrication accuracies. The wavelength of maximum Purcell enhancement proves to be the most affected performance parameter by the deviations. Finally, we show that electrical field strengths suitable for Stark-tuning of an embedded quantum dot can be reached in the identified designs.Comment: Main text including Method section, (15 pages, 5 figures, and 50 references). The data sets and used code in this work is available on Zenodo (see reference in the main text

Active mechanics reveal molecular-scale force kinetics in living oocytes

Active diffusion of intracellular components is emerging as an important process in cell biology. This process is mediated by complex assemblies of molecular motors and cytoskeletal filaments that drive force generation in the cytoplasm and facilitate enhanced motion. The kinetics of molecular motors have been precisely characterized in-vitro by single molecule approaches, however, their in-vivo behavior remains elusive. Here, we study the active diffusion of vesicles in mouse oocytes, where this process plays a key role in nuclear positioning during development, and combine an experimental and theoretical framework to extract molecular-scale force kinetics (force, power-stroke, and velocity) of the in-vivo active process. Assuming a single dominant process, we find that the nonequilibrium activity induces rapid kicks of duration $\tau \sim$ 300 $\mu$s resulting in an average force of $F \sim$ 0.4 pN on vesicles in in-vivo oocytes, remarkably similar to the kinetics of in-vitro myosin-V. Our results reveal that measuring in-vivo active fluctuations allows extraction of the molecular-scale activity in agreement with single-molecule studies and demonstrates a mesoscopic framework to access force kinetics.Comment: 20 pages, 4 figures, see ancillary files for Supplementary Materials, * equally contributing author

Prekäre Lebenslagen von Kindern und Jugendlichen - Herausforderungen für die Kinder- und Jugendhilfe. Expertise zum 9. Kinder- und Jugendbericht des Landes Nordrhein-Westfalen

[Diese Expertise] ist als Beitrag zu einer landesspezifischen Sozialberichterstattung über Kinder, Jugendliche und junge Erwachsene sowie über das Leistungsspektrum der Kinder- und Jugendhilfe zu verstehen. Damit ist sie nach Anspruch und Methode zwischen Wissenschaft, Forschung und Politik zu verorten. Sie basiert großteils auf einer empirisch-quantitativen Datengrundlage [und rückt] auf einer deskriptiven Basis relevante Aspekte der Bedingungen des Aufwachsens, der gegenwärtigen Lebensverhältnisse und der Teilhabechancen von Kindern und Jugendlichen in Nordrhein-Westfalen in den Mittelpunkt. Mit der Fokussierung auf prekäre Lebenslagen werden überwiegend die Lebensbedingungen und Teilhabechancen von Heranwachsenden aus schwierigen sozialen Verhältnissen betrachtet. … In der Expertise werden überwiegend diejenigen Ausschnitte der Lebensbedingungen der nachwachsenden Generation beleuchtet, die sich auf das Aufwachsen in öffentlicher Verantwortung beziehen. Infolgedessen geht es sowohl um eine Ausrichtung an den Akteuren selbst, d.h. den Kindern und Jugendlichen, als auch um eine Berücksichtigung der Institutionen, insbesondere der Einrichtungen der Kinder- und Jugendhilfe. (DIPF/Orig.

Isoenergetic Feeding of Low Carbohydrate-High Fat Diets Does Not Increase Brown Adipose Tissue Thermogenic Capacity in Rats

Low-carbohydrate, high-fat (LC-HF) diets are popular for inducing weight loss in overweighed adults. Adaptive thermogenesis increased by specific effects of macronutrients on energy expenditure has been postulated to induce this weight loss. We studied brown adipose tissue (BAT) morphology and function following exposure to different LC-HF diets

Radiation enhancement and "temperature" in the collapse regime of gravitational scattering

We generalize the semiclassical treatment of graviton radiation to gravitational scattering at very large energies $\sqrt{s}\gg m_P$ and finite scattering angles $\Theta_s$, so as to approach the collapse regime of impact parameters $b \simeq b_c \sim R\equiv 2G\sqrt{s}$. Our basic tool is the extension of the recently proposed, unified form of radiation to the ACV reduced-action model and to its resummed-eikonal exchange. By superimposing that radiation all-over eikonal scattering, we are able to derive the corresponding (unitary) coherent-state operator. The resulting graviton spectrum, tuned on the gravitational radius $R$, fully agrees with previous calculations for small angles $\Theta_s\ll 1$ but, for sizeable angles $\Theta_s(b)\leq \Theta_c = O(1)$ acquires an exponential cutoff of the large $\omega R$ region, due to energy conservation, so as to emit a finite fraction of the total energy. In the approach-to-collapse regime of $b\to b_c^+$ we find a radiation enhancement due to large tidal forces, so that the whole energy is radiated off, with a large multiplicity $\langle N \rangle\sim Gs \gg 1$ and a well-defined frequency cutoff of order $R^{-1}$. The latter corresponds to the Hawking temperature for a black hole of mass notably smaller than $\sqrt{s}$.Comment: 5 pages, 2 figures, talk presented at the European Physical Society Conference on High Energy Physics, 5-12 July, Venice, Ital