Quiescent X-ray emission from an evolved brown dwarf ?

I report on the X-ray detection of Gl569Bab. During a 25ksec Chandra observation the binary brown dwarf is for the first time spatially separated in X-rays from the flare star primary Gl569A. Companionship to Gl569A constrains the age of the brown dwarf pair to ~300-800 Myr. The observation presented here is only the second X-ray detection of an evolved brown dwarf. About half of the observing time is dominated by a large flare on Gl569Bab, the remainder is characterized by weak and non-variable emission just above the detection limit. This emission -- if not related to the afterglow of the flare -- represents the first detection of a quiescent corona on a brown dwarf, representing an important piece in the puzzle of dynamos in the sub-stellar regime.Comment: to appear in ApJ

Low Energy Office: Design and Evaluation

The new government building with ca. 14.000 m2 gross floor area in Innsbruck/Tirol was designed as a low energy office building. As little technical installations as possible and as much room comfort as achievable: These were the two goals, set by the builder and user. An interdisciplinary team of architects, HVAC-planners and energy designers had already developed an integrated concept for the architectural competition. This was altered and adapted during the realization phase of the building. Detailed building simulations were used to determine the interactions of building, climate and users. The integration of three glass atria into the concept, unheated and naturally ventilated, was one of the main challenges in this planning process. These atria serve as thermal buffers and use the passive gains of solar energy. Only the internal areas are ventilated mechanically. The facades were optimized to combine daylighting and protection against high solar irradiation. Reduction of the cooling load, night ventilation of the atria and groundwater cooling in the offices secure moderate temperatures without any mechanical cooling. Despite a dense utilization the building offers attractive workplaces with a comfortable room climate. The energy consumption for heating in the first fully measured year was 35 kWh/m2, which is very close to the prediction. The consumption of primary energy is low also. The measured atria air temperatures comply in general with the simulated ones. A direct comparison of simulation and measurement is planned for the future

Quiescent Radio Emission from Southern Late-type M Dwarfs and a Spectacular Radio Flare from the M8 Dwarf DENIS 1048-3956

We report the results of a radio monitoring program conducted at the Australia Telescope Compact Array to search for quiescent and flaring emission from seven nearby Southern late-type M and L dwarfs. Two late-type M dwarfs, the M7 V LHS 3003 and the M8 V DENIS 1048-3956, were detected in quiescent emission at 4.80 GHz. The observed emission is consistent with optically thin gyrosynchrotron emission from mildly relativistic (~1-10 keV) electrons with source densities n_e ~ 10 G magnetic fields. DENIS 1048-3956 was also detected in two spectacular, short-lived flares, one at 4.80 GHz (peak f_nu = 6.0+/-0.8 mJy) and one at 8.64 GHz (peak f_nu = 29.6+/-1.0 mJy) approximately 10 minutes later. The high brightness temperature (T_B >~ 10^13 K), short emission period (~4-5 minutes), high circular polarization (~100%), and apparently narrow spectral bandwidth of these events imply a coherent emission process in a region of high electron density (n_e ~ 10^11-10^12 cm^-3) and magnetic field strength (B ~ 1 kG). If the two flare events are related, the apparent frequency drift in the emission suggests that the emitting source either moved into regions of higher electron or magnetic flux density; or was compressed, e.g., by twisting field lines or gas motions. The quiescent fluxes from the radio-emitting M dwarfs violate the Gudel-Benz empirical radio/X-ray relations, confirming a trend previously noted by Berger et al. (abridged)Comment: 28 pages, 8 figures, accepted for publication in Ap

Dynamical evolution of neutrino--cooled accretion disks: detailed microphysics, lepton-driven convection, and global energetics

We present a detailed, two dimensional numerical study of the microphysical conditions and dynamical evolution of accretion disks around black holes when neutrino emission is the main source of cooling. Such structures are likely to form after the gravitational collapse of massive rotating stellar cores, or the coalescence of two compact objects in a binary (e.g., the Hulse--Taylor system). The physical composition is determined self consistently by considering two regimes: neutrino--opaque and neutrino--transparent, with a detailed equation of state which takes into account neutronization, nuclear statistical equilibrium of a gas of free nucleons and alpha particles, blackbody radiation and a relativistic Fermi gas of arbitrary degeneracy. Various neutrino emission processes are considered, with electron/positron capture onto free nucleons providing the dominant contribution to the cooling rate. We find that important temporal and spatial scales, related to the optically thin/optically thick transition are present in the disk, and manifest themselves clearly in the energy output in neutrinos. This transition produces an inversion of the lepton gradient in the innermost regions of the flow which drives convective motions, and affects the density and disk scale height radial profiles. The electron fraction remains low in the region close to the black hole, and if preserved in an outflow, could give rise to heavy element nucleosynthesis. Our specific initial conditions arise from the binary merger context, and so we explore the implications of our results for the production of gamma ray bursts.Comment: 26 pages, 12 figures, to appear in Ap

Blockade of T-cell activation by dithiocarbamates involves novel mechanisms of inhibition of nuclear factor of activated T cells.

Dithiocarbamates (DTCs) have recently been reported as powerful inhibitors of NF-kappaB activation in a number of cell types. Given the role of this transcription factor in the regulation of gene expression in the inflammatory response, NF-kappaB inhibitors have been suggested as potential therapeutic drugs for inflammatory diseases. We show here that DTCs inhibited both interleukin 2 (IL-2) synthesis and membrane expression of antigens which are induced during T-cell activation. This inhibition, which occurred with a parallel activation of c-Jun transactivating functions and expression, was reflected by transfection experiments at the IL-2 promoter level, and involved not only the inhibition of NF-kappaB-driven reporter activation but also that of nuclear factor of activated T cells (NFAT). Accordingly, electrophoretic mobility shift assays (EMSAs) indicated that pyrrolidine DTC (PDTC) prevented NF-kappaB, and NFAT DNA-binding activity in T cells stimulated with either phorbol myristate acetate plus ionophore or antibodies against the CD3-T-cell receptor complex and simultaneously activated the binding of AP-1. Furthermore, PDTC differentially targeted both NFATp and NFATc family members, inhibiting the transactivation functions of NFATp and mRNA induction of NFATc. Strikingly, Western blotting and immunocytochemical experiments indicated that PDTC promoted a transient and rapid shuttling of NFATp and NFATc, leading to their accelerated export from the nucleus of activated T cells. We propose that the activation of an NFAT kinase by PDTC could be responsible for the rapid shuttling of the NFAT, therefore transiently converting the sustained transactivation of this transcription factor that occurs during lymphocyte activation, and show that c-Jun NH2-terminal kinase (JNK) can act by directly phosphorylating NFATp. In addition, the combined inhibitory effects on NFAT and NF-KB support a potential use of DTCs as immunosuppressants

Lipid-Based Passivation in Nanofluidics

Stretching DNA in nanochannels is a useful tool for direct, visual studies of genomic DNA at the single molecule level. To facilitate the study of the interaction of linear DNA with proteins in nanochannels, we have implemented a highly effective passivation scheme based on lipid bilayers. We demonstrate virtually complete long-term passivation of nanochannel surfaces to a range of relevant reagents, including streptavidin-coated quantum dots, RecA proteins, and RecA-DNA complexes. We show that the performance of the lipid bilayer is significantly better than that of standard bovine serum albumin-based passivation. Finally, we show how the passivated devices allow us to monitor single DNA cleavage events during enzymatic degradation by DNase I. We expect that our approach will open up for detailed, systematic studies of a wide range of protein-DNA interactions with high spatial and temporal resolution

Overcoming the Back Reaction on Turbulent Motions in the Presence of Magnetic Fields

Standard magnetohydrodynamic theories, such as the mean field dynamo theory, have been criticized when the back reaction of the magnetic field on turbulent motions is neglected. For the dynamo, this back reaction has been argued to suppress the turbulent motions required for optimal mean field production. Here it is suggested that if the magnetic field is spatially intermittent, for example residing in flux tubes, the back reaction on turbulent flows may be significantly reduced.Comment: Accepted to Physical Review Letters, 15 pages, plain Te

The case for a distributed solar dynamo shaped by near-surface shear

Arguments for and against the widely accepted picture of a solar dynamo being seated in the tachocline are reviewed and alternative ideas concerning dynamos operating in the bulk of the convection zone, or perhaps even in the near-surface shear layer, are discussed. Based on the angular velocities of magnetic tracers it is argued that the observations are compatible with a distributed dynamo that may be strongly shaped by the near-surface shear layer. Direct simulations of dynamo action in a slab with turbulence and shear are presented to discuss filling factor and tilt angles of bipolar regions in such a model.Comment: 10 pages, 6 figures, Astrophys. J. 625 (scheduled for the 1 June 2005 issue

Development of a core outcome set for idiopathic clubfoot management.

AIMS: This study aims to define a set of core outcomes (COS) to allow consistent reporting in order to compare results and assist in treatment decisions for idiopathic clubfoot. METHODS: A list of outcomes will be obtained in a three-stage process from the literature and from key stakeholders (patients, parents, surgeons, and healthcare professionals). Important outcomes for patients and parents will be collected from a group of children with idiopathic clubfoot and their parents through questionnaires and interviews. The outcomes identified during this process will be combined with the list of outcomes previously obtained from a systematic review, with each outcome assigned to one of the five core areas defined by the Outcome Measures Recommended for use in Randomized Clinical Trials (OMERACT). This stage will be followed by a two round Delphi survey aimed at key stakeholders in the management of idiopathic clubfoot. The final outcomes list obtained will then be discussed in a consensus meeting of representative key stakeholders. CONCLUSION: The inconsistency in outcomes reporting in studies investigating idiopathic clubfoot has made it difficult to define the success rate of treatments and to compare findings between studies. The development of a COS seeks to define a minimum standard set of outcomes to collect in all future clinical trials for this condition, to facilitate comparisons between studies and to aid decisions in treatment. Cite this article: Bone Jt Open 2021;2(4):255-260

Promoting Functional Health in Midlife and Old Age: Long-Term Protective Effects of Control Beliefs, Social Support, and Physical Exercise

Previous studies have examined physical risk factors in relation to functional health, but less work has focused on the protective role of psychological and social factors. We examined the individual and joint protective contribution of control beliefs, social support and physical exercise to changes in functional health, beyond the influence of health status and physical risk factors in middle-aged and older adults. Given that functional health typically declines throughout adulthood, it is important to identify modifiable factors that can be implemented to maintain functioning, improve quality of life, and reduce disability.We conducted a national longitudinal study, Midlife in the United States (MIDUS), with assessments in 1995-1996 and 2004-2006, and 3,626 community-residing adults, aged 32 to 84, were included in the analyses. Functional health (Physical Functioning subscale of the SF-36) and protective factors were measured at both occasions. While controlling for socio-demographic, health status, and physical risk factors (large waist circumference, smoking, and alcohol or drug problems), a composite of the three protective variables (control beliefs, social support, and physical exercise) at Time 1 was significantly related to functional health change. The more of these factors at Time 1, the better the health maintenance over 10 years. Among middle-aged and older adults, declines in health were significantly reduced with an increased number of protective factors.Age-related declines in health were reduced among those with more protective factors up to a decade earlier in life. Modifiable psychological, social, and physical protective factors, individually and in the aggregate, are associated with maintenance of functional health, beyond the damaging effects of physical risk factors. The results are encouraging for the prospect of developing interventions to promote functional health and for reducing public health expenditures for physical disability in later life