Microwave Sinterator Freeform Additive Construction System (MS-FACS)

The harmful properties of lunar dust, such as small size, glass composition, abnormal surface area, and coatings of imbedded nanophase iron, lead to a unique coupling of the dust with microwave radiation. This coupling can be exploited for rapid sintering of lunar soil for use as a construction material that can be formed to take on an infinite number of shapes and sizes. This work describes a system concept for building structures on the lunar surface using lunar regolith (soil). This system uses the ATHLETE (All-Terrain Hex- Limbed Extra-Terrestrial Explorer) mobility system as a positioning system with a microwave print head (similar to that of a smaller-scale 3D printer). A processing system delivers the lunar regolith to the microwave print head, where the microwave print head/chamber lays down a layer of melted regolith. An arm on the ATHLETE system positions the layer depending on the desired structure

Implications of porpoise echolocation and dive behaviour on passive acoustic monitoring

Funding: The post-doctoral position for J.D.J.M. was funded by a FNU – Danish Natural Science Research Council grant to P.T.M. This study was also funded by the German Federal Agency for Nature Conservation via the grants “Effects of underwater noise on marine vertebrates” (Cluster 7, Z1.2-53302/2010/14) and “Under Water Noise Effects—UWE” (Project No. FKZ 3515822000). The contribution by T.A.M. was funded under the ACCURATE project (U.S. Navy Living Marine Resources Program, Contract No. N3943019C2176) and CEAUL (funded by FCT—Fundação para a Ciência e a Tecnologia, Portugal, through Project No. UIDB/00006/2020).Harbour porpoises are visually inconspicuous but highly soniferous echolocating marine predators that are regularly studied using passive acoustic monitoring (PAM). PAM can provide quality data on animal abundance, human impact, habitat use, and behaviour. The probability of detecting porpoise clicks within a given area ( P ̂ ) is a key metric when interpreting PAM data. Estimates of P ̂ can be used to determine the number of clicks per porpoise encounter that may have been missed on a PAM device, which, in turn, allows for the calculation of abundance and ideally non-biased comparison of acoustic data between habitats and time periods. However, P ̂ is influenced by several factors, including the behaviour of the vocalising animal. Here, the common implicit assumption that changes in animal behaviour have a negligible effect on P ̂ between different monitoring stations or across time is tested. Using a simulation-based approach informed by acoustic biologging data from 22 tagged harbour porpoises, it is demonstrated that porpoise behavioural states can have significant (up to 3× difference) effects on P ̂ . Consequently, the behavioural state of the animals must be considered in analysis of animal abundance to avoid substantial over- or underestimation of the true abundance, habitat use, or effects of human disturbance.Publisher PDFPeer reviewe

Discovery of a Faint Companion to Alcor Using MMT/AO 5 μ\mum Imaging

We report the detection of a faint stellar companion to the famous nearby A5V star Alcor (80 UMa). The companion has M-band ($\lambda$ = 4.8 $\mu$m) magnitude 8.8 and projected separation 1".11 (28 AU) from Alcor. The companion is most likely a low-mass ($\sim$0.3 \msun) active star which is responsible for Alcor's X-ray emission detected by ROSAT (L$_{\rm X}$ $\simeq$ 10$^{28.3}$ erg/s). Alcor is a nuclear member of the Ursa Major star cluster (UMa; d $\simeq$ 25 pc, age $\simeq$ 0.5 Gyr), and has been occasionally mentioned as a possible distant (709") companion of the stellar quadruple Mizar ($\zeta$ UMa). Comparing the revised Hipparcos proper motion for Alcor with the mean motion for other UMa nuclear members shows that Alcor has a peculiar velocity of 1.1 km/s, which is comparable to the predicted velocity amplitude induced by the newly-discovered companion ($\sim$1 km/s). Using a precise dynamical parallax for Mizar and the revised Hipparcos parallax for Alcor, we find that Mizar and Alcor are physically separated by 0.36 $\pm$ 0.19 pc (74 $\pm$ 39 kAU; minimum 18 kAU), and their velocity vectors are marginally consistent ($\chi^2$ probability 6%). Given their close proximity and concordant motions we suggest that the Mizar quadruple and the Alcor binary be together considered the 2nd closest stellar sextuplet. The addition of Mizar-Alcor to the census of stellar multiples with six or more components effectively doubles the local density of such systems within the local volume (d $<$ 40 pc).Comment: 28 pages, 2 figures, AJ, in press; emulateapj short version at http://www.pas.rochester.edu/~emamajek/alcor.pd

Differences in Advanced Magnetic Resonance Imaging in MOG-IgG and AQP4-IgG Seropositive Neuromyelitis Optica Spectrum Disorders: A Comparative Study

Aims: To explore differences in advanced brain magnetic resonance imaging (MRI) characteristics between myelin oligodendrocyte (MOG) immunoglobulin (IgG) and aquaporin-4 (AQP4) IgG seropositive (+) neuromyelitis optica spectrum disorders (NMOSD). Methods: 33 AQP4-IgG and 18 MOG-IgG seropositive NMOSD patients and 61 healthy control (HC) subjects were included. All 112 participants were scanned with the same standardized MRI-protocol on a 3-Tesla MRI-scanner. Brain volume and diffusion tensor imaging (DTI) parameters were assessed. Results: MOG-IgG+ patients showed reduced parallel diffusivity within white matter tracts compared to HC whereas AQP4-IgG+ showed no significant brain parenchymal damage in DTI analysis. AQP4-IgG+ patients showed reduced whole brain volumes and reduced volumes of several deep gray matter structures compared to HC whereas MOG-IgG+ patients did not show reduced brain or deep gray matter volumes compared to HC. Conclusions: Microstructural brain parenchymal damage in MOG-IgG+ patients was more pronounced than in AQP4-IgG+ patients, compared with HC, whereas normalized brain volume reduction was more severe in AQP4-IgG+ patients. Longitudinal imaging studies are warranted to further investigate this trend in NMOSD. Our results suggest that MOG-IgG+ and AQP4-IgG+ NMOSD patients differ in cerebral MRI characteristics. Advanced MRI analysis did not help to differentiate between MOG-IgG+ and AQP4-IgG+ patients in our study

The remnants of galaxy formation from a panoramic survey of the region around M31

In hierarchical cosmological models, galaxies grow in mass through the continual accretion of smaller ones. The tidal disruption of these systems is expected to result in loosely bound stars surrounding the galaxy, at distances that reach $10 - 100$ times the radius of the central disk. The number, luminosity and morphology of the relics of this process provide significant clues to galaxy formation history, but obtaining a comprehensive survey of these components is difficult because of their intrinsic faintness and vast extent. Here we report a panoramic survey of the Andromeda galaxy (M31). We detect stars and coherent structures that are almost certainly remnants of dwarf galaxies destroyed by the tidal field of M31. An improved census of their surviving counterparts implies that three-quarters of M31's satellites brighter than $M_V < -6$ await discovery. The brightest companion, Triangulum (M33), is surrounded by a stellar structure that provides persuasive evidence for a recent encounter with M31. This panorama of galaxy structure directly confirms the basic tenets of the hierarchical galaxy formation model and reveals the shared history of M31 and M33 in the unceasing build-up of galaxies.Comment: Published in Nature. Supplementary movie available at https://www.astrosci.ca/users/alan/PANDAS/Latest%20news%3A%20movie%20of%20orbit.htm

Molecular Mechanisms Driving Switch Behavior in Xylem Cell Differentiation.

Plant xylem cells conduct water and mineral nutrients. Although most plant cells are totipotent, xylem cells are unusual and undergo terminal differentiation. Many genes regulating this process are well characterized, including the Vascular-related NAC Domain 7 (VND7), MYB46, and MYB83 transcription factors, which are proposed to act in interconnected feedforward loops (FFLs). Less is known regarding the molecular mechanisms underlying the terminal transition to xylem cell differentiation. Here, we generate whole-root and single-cell data, which demonstrate that VND7 initiates sharp switching of root cells to xylem cell identity. Based on these data, we identified 4 candidate VND7 downstream target genes capable of generating this switch. Although MYB46 responds to VND7 induction, it is not among these targets. This system provides an important model to study the emergent properties that may give rise to totipotency relative to terminal differentiation and reveals xylem cell subtypes

Detection of Two Interstellar Polycyclic Aromatic Hydrocarbons via Spectral Matched Filtering

Ubiquitous unidentified infrared emission bands are seen in many astronomical sources. Although these bands are widely, if not unanimously, attributed to the collective emission from polycyclic aromatic hydrocarbons, no single species from this class has been detected in space. We present the discovery of two -CN functionalized polycyclic aromatic hydrocarbons, 1- and 2-cyanonaphthalene, in the interstellar medium aided by spectral matched filtering. Using radio observations with the Green Bank Telescope, we observe both bi-cyclic ring molecules in the molecular cloud TMC-1. We discuss potential in situ gas-phase formation pathways from smaller organic precursor molecules