Structural Neuroimaging of Anorexia Nervosa: Future Directions in the Quest for Mechanisms Underlying Dynamic Alterations.

Anorexia nervosa (AN) is a serious eating disorder characterized by self-starvation and extreme weight loss. Pseudoatrophic brain changes are often readily visible in individual brain scans, and AN may be a valuable model disorder to study structural neuroplasticity. Structural magnetic resonance imaging studies have found reduced gray matter volume and cortical thinning in acutely underweight patients to normalize following successful treatment. However, some well-controlled studies have found regionally greater gray matter and persistence of structural alterations following long-term recovery. Findings from diffusion tensor imaging studies of white matter integrity and connectivity are also inconsistent. Furthermore, despite the severity of AN, the number of existing structural neuroimaging studies is still relatively low, and our knowledge of the underlying cellular and molecular mechanisms for macrostructural brain changes is rudimentary. We critically review the current state of structural neuroimaging in AN and discuss the potential neurobiological basis of structural brain alterations in the disorder, highlighting impediments to progress, recent developments, and promising future directions. In particular, we argue for the utility of more standardized data collection, adopting a connectomics approach to understanding brain network architecture, employing advanced magnetic resonance imaging methods that quantify biomarkers of brain tissue microstructure, integrating data from multiple imaging modalities, strategic longitudinal observation during weight restoration, and large-scale data pooling. Our overarching objective is to motivate carefully controlled research of brain structure in eating disorders, which will ultimately help predict therapeutic response and improve treatment

Habitat conversion and global avian biodiversity loss

The magnitude of the impacts of human activities on global biodiversity has been documented at several organizational levels. However, although there have been numerous studies of the effects of local-scale changes in land use (e.g. logging) on the abundance of groups of organisms, broader continental or global-scale analyses addressing the same basic issues remain largely wanting. None the less, changing patterns of land use, associated with the appropriation of increasing proportions of net primary productivity by the human population, seem likely not simply to have reduced the diversity of life, but also to have reduced the carrying capacity of the environment in terms of the numbers of other organisms that it can sustain. Here, we estimate the size of the existing global breeding bird population, and then make a first approximation as to how much this has been modified as a consequence of land-use changes wrought by human activities. Summing numbers across different land-use classes gives a best current estimate of a global population of less than 100 billion breeding bird individuals. Applying the same methodology to estimates of original land-use distributions suggests that conservatively this may represent a loss of between a fifth and a quarter of pre-agricultural bird numbers. This loss is shared across a range of temperate and tropical land-use types

Identification of the lactococcal exonuclease/recombinase and its modulation by the putative Chi sequence

Studies of RecBCD–Chi interactions in Escherichia coli have served as a model to understand recombination events in bacteria. However, the existence of similar interactions has not been demonstrated in bacteria unrelated to E. coli. We developed an in vivo model to examine components of dsDNA break repair in various microorganisms. Here, we identify the major exonuclease in Lactococcus lactis, a Gram-positive organism evolutionarily distant from E. coli, and provide evidence for exonuclease–Chi interactions. Insertional mutants of L. lactis, screened as exonuclease-deficient, affected a single locus and resulted in UV sensitivity and recombination deficiency. The cloned lactococcal genes (called rexAB) restored UV resistance, recombination proficiency, and the capacity to degrade linear DNA, to an E. coli recBCD mutant. In this context, DNA degradation is specifically blocked by the putative lactococcal Chi site (5′-GCGCGTG-3′), but not by the E. coli Chi (5′-GCTGGTGG-3′) site. RexAB-mediated recombination was shown to be stimulated ≈27-fold by lactococcal Chi. Our results reveal that RexAB fulfills the biological roles of RecBCD and indicate that its activity is modulated by a short DNA sequence. We speculate that exonuclease/recombinase enzymes whose activities are modulated by short DNA sequences are widespread among bacteria

Tethered balloon measurements during Arctic autumn conditions in the framework of HALO-(AC)3

The BalloonbornE moduLar Utility for profilinG the lower Atmosphere (BELUGA) was deployed in autumn 2021 in the Arctic at the AWIPEV research station in Ny-Ålesund (Svalbard). In-situ profiles of thermodynamic parameters, broadband radiation, turbulence, aerosol particle concentrations, and cloud microphysical structure, were performed. Additionally, samples of ice nucleating particles were collected. Thermal infrared radiation profiles are presented for different cloud conditions. The data provides the base for studying the vertical distribution of cloud radiative effects, and extends the common view of the bi-modal distribution of the Arctic surface energy budget.Das Fesselballonsystem BalloonbornE moduLar Utility for profilinG the lower Atmosphere (BELUGA) wurde im Herbst 2021 an der Forschungsstation Ny-Ålesund in der Arktis eingesetzt. Es wurden In-situ Profile von thermodynamischen Parametern, breitbandiger Strahlung, Turbulenz, Aerosolpartikelkonzentrationen und der mikrophysikalischer Wolkenstruktur erstellt. Zusätzlich wurden Proben von eiskeimbildenden Partikeln gesammelt. Strahlungsprofile wurden unter verschiedenen Wolkenbedeckungen gemessen und quantifizieren die vertikale Verteilung der Wolkenstrahlungseffekte. Die Profilmessungen erweitern damit die für bodennahe Messungen bekannte modale Verteilung des Energiehaushalts der Arktis

The new BELUGA setup for collocated turbulence and radiation measurements using a tethered balloon: First applications in the cloudy Arctic boundary layer

The new BELUGA (Balloon-bornE moduLar Utility for profilinG the lower Atmosphere) tethered balloon system is introduced. It combines a set of instruments to measure turbulent and radiative parameters and energy fluxes. BELUGA enables collocated measurements either at a constant altitude or as vertical profiles up to 1.5km in height. In particular, the instrument payload of BELUGA comprises three modular instrument packages for high-resolution meteorological, wind vector and broadband radiation measurements. Collocated data acquisition allows for estimates of the driving parameters in the energy balance at various heights. Heating rates and net irradiances can be related to turbulent fluxes and local turbulence parameters such as dissipation rates. In this paper the technical setup, the instrument performance, and the measurement strategy of BELUGA are explained. Furthermore, the high vertical resolution due to the slow ascent speed is highlighted as a major advantage of tethered balloon-borne observations. Three illustrative case studies of the first application of BELUGA in the Arctic atmospheric boundary layer are presented. As a first example, measurements of a single-layer stratocumulus are discussed. They show a pronounced cloud top radiative cooling of up to 6K h-1. To put this into context, a second case elaborates respective measurements with BELUGA in a cloudless situation. In a third example, a multilayer stratocumulus was probed, revealing reduced turbulence and negligible cloud top radiative cooling for the lower cloud layer. In all three cases the net radiative fluxes are much higher than turbulent fluxes. Altogether, BELUGA has proven its robust performance in cloudy conditions of the Arctic atmospheric boundary layer

Influence of local surface albedo variability and ice crystal shape on passive remote sensing of thin cirrus

Airborne measurements of solar spectral radiance reflected by cirrus are performed with the HALO-Solar Radiation (HALO-SR) instrument onboard the High Altitude and Long Range Research Aircraft (HALO) in November 2010. The data are used to quantify the influence of surface albedo variability on the retrieval of cirrus optical thickness and crystal effective radius. The applied retrieval of cirrus optical properties is based on a standard two-wavelength approach utilizing measured and simulated reflected radiance in the visible and near-infrared spectral region. Frequency distributions of the surface albedos from Moderate resolution Imaging Spectroradiometer (MODIS) satellite observations are used to compile surface-albedo-dependent lookup tables of reflected radiance. For each assumed surface albedo the cirrus optical thickness and effective crystal radius are retrieved as a function of the assumed surface albedo. The results for the cirrus optical thickness are compared to measurements from the High Spectral Resolution Lidar (HSRL). The uncertainty in cirrus optical thickness due to local variability of surface albedo in the specific case study investigated here is below 0.1 and thus less than that caused by the measurement uncertainty of both instruments. It is concluded that for the retrieval of cirrus optical thickness the surface albedo variability is negligible. However, for the retrieval of crystal effective radius, the surface albedo variability is of major importance, introducing uncertainties up to 50%. Furthermore, the influence of the bidirectional reflectance distribution function (BRDF) on the retrieval of crystal effective radius was investigated and quantified with uncertainties below 10%, which ranges below the uncertainty caused by the surface albedo variability. The comparison with the independent lidar data allowed for investigation of the role of the crystal shape in the retrieval. It is found that if assuming aggregate ice crystals, the HSRL observations fit best with the retrieved optical thickness from HALO-SR

On the π\pi and KK as qqˉq \bar q Bound States and Approximate Nambu-Goldstone Bosons

We reconsider the two different facets of $\pi$ and $K$ mesons as $q \bar q$ bound states and approximate Nambu-Goldstone bosons. We address several topics, including masses, mass splittings between $\pi$ and $\rho$ and between $K$ and $K^*$, meson wavefunctions, charge radii, and the $K-\pi$ wavefunction overlap.Comment: 15 pages, late

Investigating the potential to retrieve cloud droplet number concentration from ship-based measurements of spectral solar radiance during EUREC4A

Ship-based cloud remote sensing observations made onboard R/V Meteor during the ElUcidating the RolE of Cloud-Circulation Coupling in ClimAte, EUREC4A, campaign are presented and used to calculate cloud droplet number concentrations. The calculation is based on cloud liquid water path LWP and droplet effective radius reff retrieved from spectral measurements of transmitted solar radiance. It is shown that measurement uncertainties and retrieval assumptions impact the accuracy of the results. A case study indicates that the retrieval of LWP and reff is most affected by 3D-radiative effects in case of shallow cumulus and drizzle, which violates the adiabatic theory and plan-parallel geometry on which the radiative transfer simulations of the retrieval are based. Depending on the cloud thickness, the retrieval of reff might suffers from ambiguity. These retrieval uncertainties and their implications on the estimated cloud droplet number concentration are investigated by a sensitivity study. The analysis showed that most of the uncertainty is introduced by reff, whereas LWP contributes significantly to the uncertainty only for thin clouds. Therefore, it is concluded that only selected cloud cases, which do not violate the retrieval assumption, such as stratiform cloud layers, are suited to apply the retrieval approach in further studies.Fernerkundungsmessungen von Wolken auf dem Forschungsschiff R/V Meteor während der ElUcidating the RolE of Cloud-Circulation Coupling in ClimAte, EUREC4A, Kampagnewerden vorgestellt und zur Berechnung der Tröpfchenanzahlkonzentration verwendet. Die Berechnung basiert auf Messungen des Flüssigwasserpfads LWP und dem effektiven Tröpfchenradius reff, welche aus spektralen Messungen der transmittierten solaren Strahldichte abgeleitet wurden. Es wird gezeigt, dass Messunsicherheiten und Annahmen bei der Ableitung der Wolkeneigenschaften die Genauigkeit der Ergebnisse beeinflussen. Eine Fallstudie zeigt, dass die Ableitung von LWP und reff am stärksten durch 3-dimensionale Strahlungseffekte von flachen Cumuli und Nieselregen beeinflusst wird. Beides wiederspricht den Idealisierungen von adiabatischen Wolken und einer planparallelen Geometrie, auf denen die Strahlungstransfersimulationen des Verfahrens beruhen. Abhängig von der Wolkendicke kann die Ableitung von reff zusätzlich durch Mehrdeutigkeiten beeinflusst sein