Regional modelling of permafrost thicknesses over the past 130 ka: implications for permafrost development in Great Britain

The greatest thicknesses of permafrost in Great Britain most likely occurred during the last glacial–interglacial cycle, as this is when some of the coldest conditions occurred during the last 1 000 000 years. The regional development of permafrost across Great Britain during the last glacial–interglacial cycle was modelled from a ground surface temperature history based on mean annual temperatures and the presence of glacier ice. To quantify the growth and decay of permafrost, modelling was undertaken at six locations across Great Britain that represent upland glaciated, lowland glaciated, upland unglaciated and lowland unglaciated conditions. Maximum predicted permafrost depths derived in this academic study range between several tens of metres to over 100 m depending upon various factors including elevation, glacier ice cover, geothermal heat flux and air temperature. In general, the greatest maximum permafrost thicknesses occur at upland glaciated locations, with minimum thickness at lowland sites. Current direct geological evidence for permafrost is from surface or shallow processes, mainly associated with the active layer. Further research is recommended to identify the imprint of freeze/thaw conditions in permanently frozen porous rocks from beneath the active layer

Affordable Rotating Fluid Demonstrations for Geoscience Education: The DIYnamics Project

Demonstrations using rotating tanks of fluid can help demystify otherwise counterintuitive behaviors of atmospheric, oceanic, and planetary interior fluid motions. But the expense and complicated assembly of existing rotating table platforms limit their appeal for many schools, especially those below the university level. Here, we introduce Do-It-Yourself Dynamics (DIYnamics), a project developing extremely low-cost rotating tank platforms and accompanying teaching materials. The devices can be assembled in a few minutes from household items, all available for purchase online. Ordering, assembly, and operation instructions are available on the DIYnamics website. Videos using these and other rotating tables to teach specific concepts such as baroclinic instability are available on the DIYnamics YouTube channel—including some in Spanish. The devices, lesson plans, and demonstrations have been successfully piloted at multiple middle schools, in a university course, and at public science outreach events. These uses to date convince us of the DIYnamics materials’ pedagogical value for instructors from well-versed university professors to K–12 science teachers with little background in fluid dynamics

Analysis of the asymmetrically expressed Ablim1 locus reveals existence of a lateral plate Nodal-independent left sided signal and an early, left-right independent role for nodal flow

BACKGROUND: Vertebrates show clear asymmetry in left-right (L-R) patterning of their organs and associated vasculature. During mammalian development a cilia driven leftwards flow of liquid leads to the left-sided expression of Nodal, which in turn activates asymmetric expression of the transcription factor Pitx2. While Pitx2 asymmetry drives many aspects of asymmetric morphogenesis, it is clear from published data that additional asymmetrically expressed loci must exist. RESULTS: A L-R expression screen identified the cytoskeletally-associated gene, actin binding lim protein 1 (Ablim1), as asymmetrically expressed in both the node and left lateral plate mesoderm (LPM). LPM expression closely mirrors that of Nodal. Significantly, Ablim1 LPM asymmetry was detected in the absence of detectable Nodal. In the node, Ablim1 was initially expressed symmetrically across the entire structure, resolving to give a peri-nodal ring at the headfold stage in a flow and Pkd2-dependent manner. The peri-nodal ring of Ablim1 expression became asymmetric by the mid-headfold stage, showing stronger right than left-sided expression. Node asymmetry became more apparent as development proceeded; expression retreated in an anticlockwise direction, disappearing first from the left anterior node. Indeed, at early somite stages Ablim1 shows a unique asymmetric expression pattern, in the left lateral plate and to the right side of the node. CONCLUSION: Left LPM Ablim1 is expressed in the absence of detectable LPM Nodal, clearly revealing existence of a Pitx2 and Nodal-independent left-sided signal in mammals. At the node, a previously unrecognised action of early nodal flow and Pkd2 activity, within the pit of the node, influences gene expression in a symmetric manner. Subsequent Ablim1 expression in the peri-nodal ring reveals a very early indication of L-R asymmetry. Ablim1 expression analysis at the node acts as an indicator of nodal flow. Together these results make Ablim1 a candidate for controlling aspects of L-R identity and patterning

Aging and Recovery After Resistance-Exercise-Induced Muscle Damage: Current Evidence and Implications for Future Research

Accepted author manuscript version reprinted, by permission, from Journal of Aging and Physical Activity, 2021, 29(3): 544-551, https://doi.org/10.1123/japa.2020-0201. © Human Kinetics, Inc.Aging is anecdotally associated with a prolonged recovery from resistance training, though current literature remains equivocal. This brief review considers the effects of resistance training on indirect markers of muscle damage and recovery (i.e., muscle soreness, blood markers, and muscle strength) in older males. With no date restrictions, four databases were searched for articles relating to aging, muscle damage, and recovery. Data from 11 studies were extracted for review. Of these, four reported worse symptoms in older compared with younger populations, while two have observed the opposite, and the remaining studies (n = 6) proposed no differences between age groups. It appears that resistance training can be practiced in older populations without concern for impaired recovery. To improve current knowledge, researchers are urged to utilize more ecologically valid muscle-damaging bouts and investigate the mechanisms which underpin the recovery of muscle soreness and strength after exercise in older populations

Efficient detection and characterization of exoplanets within the diffraction limit: nulling with a mode-selective photonic lantern

Coronagraphs allow for faint off-axis exoplanets to be observed, but are limited to angular separations greater than a few beam widths. Accessing closer-in separations would greatly increase the expected number of detectable planets, which scales inversely with the inner working angle. The Vortex Fiber Nuller (VFN) is an instrument concept designed to characterize exoplanets within a single beam-width. It requires few optical elements and is compatible with many coronagraph designs as a complementary characterization tool. However, the peak throughput for planet light is limited to about 20%, and the measurement places poor constraints on the planet location and flux ratio. We propose to augment the VFN design by replacing its single-mode fiber with a six-port mode-selective photonic lantern, retaining the original functionality while providing several additional ports that reject starlight but couple planet light. We show that the photonic lantern can also be used as a nuller without a vortex. We present monochromatic simulations characterizing the response of the Photonic Lantern Nuller (PLN) to astrophysical signals and wavefront errors, and show that combining exoplanet flux from the nulled ports significantly increases the overall throughput of the instrument. We show using synthetically generated data that the PLN detects exoplanets more effectively than the VFN. Furthermore, with the PLN, the exoplanet can be partially localized, and its flux ratio constrained. The PLN has the potential to be a powerful characterization tool complementary to traditional coronagraphs in future high-contrast instruments.Comment: 15 pages, 12 figure

Expansion of W 3(OH)

A direct measurement of the expansion of W 3(OH) is made by comparing Very Large Array images taken about 10 yr apart. The expansion is anisotropic with a typical speed of 3 to 5 km/s, indicating a dynamical age of only 2300 yr. These observations are inconsistent with either the freely expanding shell model or a simple bow shock model. The most favored model is a slowly expanding shell-like HII region, with either a fast rarefied flow or another less massive diffuse ionized region moving towards the observer. There is also a rapidly evolving source near the projected center of emission, perhaps related to the central star.Comment: LaTeX file, 28 pages, includes 8 figures. To appear in ApJ in December 10 (1998) issue. Also available at http://www.submm.caltech.edu/~kawamura/w3oh_pp.p

Association between HLA Class I and Class II Alleles and the Outcome of West Nile Virus Infection: An Exploratory Study

BACKGROUND: West Nile virus (WNV) infection is asymptomatic in most individuals, with a minority developing symptoms ranging from WNV fever to serious neuroinvasive disease. This study investigated the impact of host HLA on the outcome of WNV disease. METHODS: A cohort of 210 non-Hispanic mostly white WNV(+) subjects from Canada and the U.S. were typed for HLA-A, B, C, DP, DQ, and DR. The study subjects were divided into three WNV infection outcome groups: asymptomatic (AS), symptomatic (S), and neuroinvasive disease (ND). Allele frequency distribution was compared pair-wise between the AS, S, and ND groups using χ2 and Fisher's exact tests and P values were corrected for multiple comparisons (Pc). Allele frequencies were compared between the groups and the North American population (NA) used as a control group. Logistic regression analysis was used to evaluate the potential synergistic effect of age and HLA allele phenotype on disease outcome. RESULTS: The alleles HLA-A*68, C*08 and DQB*05 were more frequently associated with severe outcomes (ND vs. AS, P(A*68) = 0.013/Pc = 0.26, P(C*08) = 0.0075/Pc = 0.064, and P(DQB1*05) = 0.029/Pc = 0.68), However the apparent DQB1*05 association was driven by age. The alleles HLA-B*40 and C*03 were more frequently associated with asymptomatic outcome (AS vs. S, P(B*40) = 0.021/Pc = 0.58 and AS vs. ND P(C*03) = 0.039/Pc = 0.64) and their frequencies were lower within WNV(+) subjects with neuroinvasive disease than within the North American population (NA vs. S, P(B*40) = 0.029 and NA vs. ND, P(C*03) = 0.032). CONCLUSIONS: Host HLA may be associated with the outcome of WNV disease; HLA-A*68 and C*08 might function as "susceptible" alleles, whereas HLA-B*40 and C*03 might function as "protective" alleles

Dermal denticle assemblages in coral reef sediments correlate with conventional shark surveys

Abstract It is challenging to assess long‐term trends in mobile, long‐lived and relatively rare species such as sharks. Despite ongoing declines in many coastal shark populations, conventional surveys might be too fleeting and too recent to describe population trends over decades to millennia. Placing recent shark declines into historical context should improve management efforts as well as our understanding of past ecosystem dynamics. A new palaeoecological approach for surveying shark abundance on coral reefs is to quantify dermal denticle assemblages preserved in sediments. This approach assumes that denticle accumulation rates correlate with shark abundances. Here, we test this assumption by comparing the denticle record in surface sediments to three conventional shark survey methods at Palmyra Atoll, Line Islands, central Pacific Ocean, where shark density is high and spatially heterogeneous. We generally found a significant positive correlation between denticle accumulation rates and shark abundances derived from underwater visual census, baited remote underwater video and hook and line surveys. Denticle accumulation rates reflected shark abundances, suggesting that denticle assemblages can preserve a signal of time‐averaged shark abundance in low‐energy coral reef environments. We offer suggestions for applying this tool to measure shark abundance over long time‐scales in other contexts

The Milky Way Tomography With SDSS. III. Stellar Kinematics

We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r 20 degrees). We find that in the region defined by 1 kpc < Z < 5 kpc and 3 kpc < R < 13 kpc, the rotational velocity for disk stars smoothly decreases, and all three components of the velocity dispersion increase, with distance from the Galactic plane. In contrast, the velocity ellipsoid for halo stars is aligned with a spherical coordinate system and appears to be spatially invariant within the probed volume. The velocity distribution of nearby (Z < 1 kpc) K/M stars is complex, and cannot be described by a standard Schwarzschild ellipsoid. For stars in a distance-limited subsample of stars (< 100 pc), we detect a multi-modal velocity distribution consistent with that seen by HIPPARCOS. This strong non-Gaussianity significantly affects the measurements of the velocity-ellipsoid tilt and vertex deviation when using the Schwarzschild approximation. We develop and test a simple descriptive model for the overall kinematic behavior that captures these features over most of the probed volume, and can be used to search for substructure in kinematic and metallicity space. We use this model to predict further improvements in kinematic mapping of the Galaxy expected from Gaia and the Large Synoptic Survey Telescope.NSF AST-615991, AST-0707901, AST-0551161, AST-02-38683, AST-06-07634, AST-0807444, PHY05-51164NASA NAG5-13057, NAG5-13147, NNXO-8AH83GPhysics Frontier Center/Joint Institute for Nuclear Astrophysics (JINA) PHY 08-22648U.S. National Science FoundationMarie Curie Research Training Network ELSA (European Leadership in Space Astrometry) MRTN-CT-2006-033481Fermi Research Alliance, LLC, United States Department of Energy DE-AC02-07CH11359Alfred P. Sloan FoundationParticipating InstitutionsJapanese MonbukagakushoMax Planck SocietyHigher Education Funding Council for EnglandMcDonald Observator

The path to detecting extraterrestrial life with astrophotonics

Astrophysical research into exoplanets has delivered thousands of confirmed planets orbiting distant stars. These planets span a wide ranges of size and composition, with diversity also being the hallmark of system configurations, the great majority of which do not resemble our own solar system. Unfortunately, only a handful of the known planets have been characterized spectroscopically thus far, leaving a gaping void in our understanding of planetary formation processes and planetary types. To make progress, astronomers studying exoplanets will need new and innovative technical solutions. Astrophotonics -- an emerging field focused on the application of photonic technologies to observational astronomy -- provides one promising avenue forward. In this paper we discuss various astrophotonic technologies that could aid in the detection and subsequent characterization of planets and in particular themes leading towards the detection of extraterrestrial life.Comment: 9 pages, 2 figures, SPIE Optics and Photonics conferenc