The nearby population of M dwarfs with WISE: A search for warm circumstellar dust

Circumstellar debris disks are important because of their connection to planetary systems. An efficient way to identify these systems is through their infrared excess. Most studies so far concentrated on early-type or solar-type stars, but less effort has gone into investigating M dwarfs. We characterize the mid-infrared photometric behavior of M dwarfs and search for infrared excess in nearby M dwarfs taken from the volume-limited RECONS sample using data from the WISE satellite and the 2MASS catalog. Our sample consists of 85 sources encompassing 103 M dwarfs. We derive empirical infrared colors from these data and discuss their errors. Based on this, we check the stars for infrared excess and discuss the minimum excess we would be able to detect. Other than the M8.5 dwarf SCR 1845-6357 A, where the excess is produced by a known T6 companion, we detect no excesses in any of our sample stars. The limits we derive for the 22um excess are slightly higher than the usual detection limit of 10-15% for Spitzer studies, but including the [12]-[22] color in our analysis allows us to derive tight constraints on the fractional dust luminosity L_dust/L_star. We show that this result is consistent with M dwarf excesses in the mid-inrared being as frequent as excesses around earlier-type stars. The low detection rate could be an age effect. We also present a tentative excess detection at 22um around the known cold debris disk M dwarf AU Mic, which is not part of our statistical sample. There is still no clear detection of a mid-infrared excess around any old (>30 Myr) main-sequence M dwarf. It is unclear whether this is due to a different dust evolution around M dwarfs or whether this is an age effect combined with the diffculties involved in searching M dwarfs for infrared excesses. A significantly larger sample of well-studied M dwarfs is required to solve this question.Comment: Accepted for publication in A&A, 15 pages, 7 figure

Neuropsychologische Frühzeichen der häufigsten Demenzformen

Die häufigsten Demenzformen zeichnen sich durch charakteristische neuropsychologische Störungsmuster in der präklinischen und frühen klinischen Phase aus. Eine die wichtigsten kognitiven Bereiche mit sorgfältig normierten Tests prüfende neuropsychologische Untersuchung kann zur frühen Differentialdiagnose und zur Identifikation von Vorläufersyndromen beitragen

Entwicklung und Validierung des Bedürfnisinventars bei Gedächtnisstörungen (BIG-65): Krankheitskorrelierte Bedürfnisse bei Menschen mit Hirnleistungsstörungen und Demenz

Zusammenfassung: Hintergrund: Der Bedarf an einer systematischen Erfassung krankheitskorrelierter Patientenbedürfnisse bei Hirnleistungsstörungen und Demenz zur Auswahl optimaler Behandlungsoptionen steigt zunehmend. Es fehlt jedoch an validen Messinstrumenten, die zur Erfassung krankheitskorrelierter Bedürfnisse auch bei Menschen mit Demenz eingesetzt werden können. Methode: Die Studie umfasst die Konstruktion und Validierung des Bedürfnisinventars bei Gedächtnisstörungen (BIG-65) zur Erfassung krankheitskorrelierter Bedürfnisse. Der BIG-65 wurde theoriegeleitet entwickelt und basiert auf einer systematischen Literaturrecherche. Er wurde in einer Abklärungsstation, nach umfassender Untersuchung und Diagnosestellung, hinsichtlich seiner psychometrischen Eigenschaften an einer Gelegenheitsstichprobe (n = 83) validiert. Ergebnisse: Der BIG-65 hat 66Items und bietet neben einer breiten Auswahl an biopsychosozialen und umweltbezogenen Bedürfnissen eine geeignete Struktur zur Erfassung krankheitskorrelierter Bedürfnisse bei Menschen mit Hirnleistungsstörungen. Er verfügt über eine besonders hohe Augenscheinvalidität und eine sehr hohe Test-Retest-Reliabilität (rtt = 0,916). Im Mittel wurden 3,5 (SD = 3,7) unabgedeckte Bedürfnisse angegeben. Am häufigsten genannt wurden: "weniger vergessen" (50%), "bessere Konzentration" (23,2%), "Informationen zur Krankheit" (20,7%), "Informationen über Behandlungen" (17,1%) sowie "sich weniger Sorgen machen", "weniger gereizt sein", "Verbesserung der Stimmung", "Verbesserung der Orientierung" (alle 13,4%). Bedürfnisprofile unterscheiden sich zwischen verschiedenen Patientengruppen mit präklinischen (subjektive und milde kognitive Beeinträchtigung) und klinischen (Demenz) Hirnleistungsstörungen. Schlussfolgerungen: Krankheitskorrelierte Bedürfnisse können mit dem BIG-65 bis zu einer mittelschweren Demenz reliabel erfasst werden. Mit zunehmendem Demenzschweregrad oder einem Mini-Mental-Status <20Punkten sollte die Erfassung, z.B. mit zusätzlichen Beobachtungsmethoden des emotionalen Ausdrucks, ergänzt werden. Die Ergebnisse zeigen, dass Menschen mit Hirnleistungsstörungen individuelle Strategien zur Stabilisierung von Lebensqualität verfolgen. Neben einem objektiven Assessment von Krankheitssymptomen kann die Priorisierung optimaler Behandlungsmaßnahmen von der systematischen Erfassung krankheitskorrelierter Patientenbedürfnisse profitiere

[NEt3Me][O3], Synthesis, Crystal Growth and Crystal Structure Analysis

[NEt3Me][O3] was obtained for the first time by an ion exchange reaction in liquid ammonia. It was thoroughly characterized by X‐Ray diffraction [P21; a=598.51(4) pm, b=1032.03(7) pm, c=723.83(6) pm, β=92.677(3)°, R=0.0384, 15070 reflections] applying non‐spherical and spherical atomic form factors for the refinements. In contrast to previous reported ozonides, [NEt3Me][O3] is the first to adopt the tungsten carbide (WC) motif of cation/ anion arragemnent and shows an untypical hydrogen bond between the central oxygen atom of the ozonide and the cation. Additionally, IR spectroscopy as well as quantum‐chemical calculations were applied to further characterize the compound. The obtained ozonide showed high solubility in ammonia as well as acetonitrile and good properties as a synthon in ozonide chemistry

Small vs large dust grains in transitional disks: do different cavity sizes indicate a planet?

Transitional disks represent a short stage of the evolution of circumstellar material. Studies of dust grains in these objects can provide pivotal information on the mechanisms of planet formation. Dissimilarities in the spatial distribution of small (micron-size) and large (millimeter-size) dust grains have recently been pointed out. Constraints on the small dust grains can be obtained by imaging the distribution of scattered light at near-infrared wavelengths. We aim at resolving structures in the surface layer of transitional disks (with particular emphasis on the inner 10 - 50 AU), thus increasing the scarce sample of high resolution images of these objects. We obtained VLT/NACO near-IR high-resolution polarimetric differential imaging observations of SAO 206462 (HD135344B). This technique allows one to image the polarized scattered light from the disk without any occulting mask and to reach an inner working angle of 0.1''. A face-on disk is detected in H and Ks bands between 0.1'' and 0.9''. No significant differences are seen between the H and Ks images. In addition to the spiral arms, these new data allow us to resolve for the first time an inner cavity for small dust grains. The cavity size (about 28 AU) is much smaller than what is inferred for large dust grains from (sub)mm observations (39 to 50 AU). The interaction between the disk and potential orbiting companion(s) can explain both the spiral arm structure and the discrepant cavity sizes for small and large dust grains. One planet may be carving out the gas (and, thus, the small grains) at 28 AU, and generating a pressure bump at larger radii (39 AU), which holds back the large grains. We analytically estimate that, in this scenario, a single giant planet (with a mass between 5 and 15 Jupiter masses) at 17 to 20 AU from the star is consistent with the observed cavity sizes.Comment: 11 pages, 6 figures; accepted for publication in A&

Behavioural endophenotypes in mice lacking the auxiliary GABAB receptor subunit KCTD16

Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain and is implicated in the pathophysiology of a number of neuropsychiatric disorders. The GABAB receptors are G-protein coupled receptors consisting of principle subunits and auxiliary potassium channel tetramerization domain (KCTD) subunits. The KCTD subunits 8, 12, 12b and 16 are cytosolic proteins that determine the kinetics of the GABAB receptor response. Previously, we demonstrated that Kctd12 null mutant mice (Kctd12(-/-)) exhibit increased auditory fear learning and that Kctd12(+/-) mice show altered circadian activity, as well as increased intrinsic excitability in hippocampal pyramidal neurons. KCTD16 has been demonstrated to influence neuronal excitability by regulating GABAB receptor-mediated gating of postsynaptic ion channels. In the present study we investigated for behavioural endophenotypes in Kctd16(-/-) and Kctd16(+/-) mice. Compared with wild-type (WT) littermates, auditory and contextual fear conditioning were normal in both Kctd16(-/-) and Kctd16(+/-) mice. When fear memory was tested on the following day, Kctd16(-/-) mice exhibited less extinction of auditory fear memory relative to WT and Kctd16(+/-) mice, as well as more contextual fear memory relative to WT and, in particular, Kctd16(+/-) mice. Relative to WT, both Kctd16(+/-) and Kctd16(-/-) mice exhibited normal circadian activity. This study adds to the evidence that auxillary KCTD subunits of GABAB receptors contribute to the regulation of behaviours that could constitute endophenotypes for hyper-reactivity to aversive stimuli in neuropsychiatric disorders

Substantial increase in minimum lake surface temperatures under climate change

The annual minimum of lake surface water temperature influences ecological and biogeochemical processes, but variability and change in this extreme has not been investigated. Here, we analysed observational data from eight European lakes and investigated the changes in annual minimum surface water temperature. We found that, between 1973 and 2014, the annual minimum lake surface temperature has increased at an average rate of +0.35°C decade-1; comparable to the rate of summer average lake surface temperature change during the same period (+0.32°C decade-1). Coherent responses to climatic warming are observed between the increase in annual minimum lake surface temperature and the increase in winter air temperature variations. As a result of the rapid warming of annual minimum lake surface temperatures, some of the studied lakes no longer reach important minimum surface temperature thresholds that occur in winter, with complex and significant potential implications for lakes and the ecosystem services that they provide

Canopy nitrogen, carbon assimilation, and albedo in temperate and boreal forests: Functional relations and potential climate feedbacks

The availability of nitrogen represents a key constraint on carbon cycling in terrestrial ecosystems, and it is largely in this capacity that the role of N in the Earth\u27s climate system has been considered. Despite this, few studies have included continuous variation in plant N status as a driver of broad-scale carbon cycle analyses. This is partly because of uncertainties in how leaf-level physiological relationships scale to whole ecosystems and because methods for regional to continental detection of plant N concentrations have yet to be developed. Here, we show that ecosystem CO2 uptake capacity in temperate and boreal forests scales directly with whole-canopy N concentrations, mirroring a leaf-level trend that has been observed for woody plants worldwide. We further show that both CO2 uptake capacity and canopy N concentration are strongly and positively correlated with shortwave surface albedo. These results suggest that N plays an additional, and overlooked, role in the climate system via its influence on vegetation reflectivity and shortwave surface energy exchange. We also demonstrate that much of the spatial variation in canopy N can be detected by using broad-band satellite sensors, offering a means through which these findings can be applied toward improved application of coupled carbon cycle–climate models

The Trans-Planckian Problem of Inflationary Cosmology

In most current models of inflation based on a weakly self-coupled scalar matter field minimally coupled to gravity, the period of inflation lasts so long that, at the beginning of the inflationary period, the physical wavelengths of comoving scales which correspond to the present large-scale structure of the Universe were smaller than the Planck length. Thus, the usual computations of the spectrum of fluctuations in these models involve extrapolating low energy physics (both in the matter and gravitational sector) into regions where this physics is not applicable. In this paper we demonstrate that the usual predictions of inflation for the spectrum of cosmological fluctuations do indeed depend on the hidden assumptions about super-Planck scale physics. We introduce a class of modified dispersion relations to mimic possible effects of super-Planck scale physics, and show that in some cases important deviations from the usual predictions of inflation are obtained. Some implications of this result for the unification of fundamental physics and early Universe cosmology are discussed.Comment: 16 pages, 2 figures. One important correction in the Corley/Jacobson case with b_m>0 and some misprints corrected. Version published in PR

Telehealth use by walk-in patients who subsequently visited an academic emergency department: a repeated cross-sectional study during the COVID-19 summer 2021.

AIM OF THE STUDY During the COVID-19 pandemic, telehealth use increased worldwide in a variety of medical specialities and reached new population groups. A baseline survey of telehealth use prior to admission to the emergency department (ED) conducted before COVID-19 concluded that predominantly well-educated men used telehealth. It is unclear how COVID-19 changed the use of telehealth in Swiss emergency patients. We therefore aimed to investigate (i) the frequency of telehealth use during the pandemic, and (ii) how the pandemic has influenced telehealth use and users. MATERIALS AND METHODS A repeated cross-sectional study was conducted among ED walk-in patients at a tertiary university hospital in Switzerland. The study took place one and a half years after the first confirmed COVID-19 case, during 30 shifts from 8 to 29 July 2021 and compared with the baseline survey conducted in 2019. Eligible patients were questioned about their use of, and attitudes to telehealth. RESULTS A total of 1020 patients were screened for the COVID survey and 443 complete questionnaires were evaluated. A trend towards a general increase (+6.4%) in telehealth use was demonstrated (50.3%, n = 223 COVID survey vs 43.9%, n = 183 baseline survey; p = 0.058), with a shift to more female patients using telehealth in the COVID survey (female 54.9%, n = 124 vs 45.1%, n = 102; p = 0.052). During the pandemic, first use of telehealth was reported by 12.2% (n = 54) of patients, with a significant increase among patients with low educational status, and the latter patients often indicated that they did not plan to use telehealth after the pandemic. The perceived usefulness of telehealth and adherence to recommendations increased in the COVID survey compared with the baseline survey (adherence 90.3%, n = 149, vs 78.0%, n = 131; p = 0.002). CONCLUSION We found a trend towards increased use of telehealth among Swiss ED patients. First-time users of telehealth were predominantly less educated and inclusion of these user groups may not be sustainable, as was indicated by the patients. COVID-19 led to greater adherence to telehealth recommendations and higher perceived usefulness. This could be due to the limited access to healthcare providers due to pandemic precautions. When offering telehealth, the needs of all patient groups must be considered, in order to ensure that telehealth provides the greatest benefit with lower barriers to use