Galaxy UV-luminosity function and reionization constraints on axion dark matter

If the dark matter (DM) were composed of axions, then structure formation in the Universe would be suppressed below the axion Jeans scale. Using an analytic model for the halo mass function of a mixed DM model with axions and cold dark matter, combined with the abundance-matching technique, we construct the UV-luminosity function. Axions suppress high-$z$ galaxy formation and the UV-luminosity function is truncated at a faintest limiting magnitude. From the UV-luminosity function, we predict the reionization history of the universe and find that axion DM causes reionization to occur at lower redshift. We search for evidence of axions using the Hubble Ultra Deep Field UV-luminosity function in the redshift range $z=6$-$10$, and the optical depth to reionization, $\tau$, as measured from cosmic microwave background polarization. All probes we consider consistently exclude $m_a\lesssim 10^{-23}\text{ eV}$ from contributing more than half of the DM, with our strongest constraint ruling this model out at more than $8\sigma$ significance. In conservative models of reionization a dominant component of DM with $m_a=10^{-22}\text{ eV}$ is in $3\sigma$ tension with the measured value of $\tau$, putting pressure on an axion solution to the cusp-core problem. Tension is reduced to $2\sigma$ for the axion contributing only half of the DM. A future measurement of the UV-luminosity function in the range $z=10$-$13$ by JWST would provide further evidence for or against $m_a=10^{-22}\text{ eV}$. Probing still higher masses of $m_a=10^{-21}\text{ eV}$ will be possible using future measurements of the kinetic Sunyaev-Zel'dovich effect by Advanced ACTPol to constrain the time and duration of reionization.Comment: 17 pages, 8 figures, 2 tables. v2: Minor Changes. References added. Published in MNRA

Variability of the southern Antarctic Circumpolar Current front north of South Georgia

South Georgia (54°S, 37°W) is an island in the eastern Scotia Sea, South Atlantic that lies in the path of the Antarctic Circumpolar Current (ACC). The southern ACC front (SACCF), one of three major fronts associated with the ACC, wraps anticyclonically around South Georgia and then retroflects north of the island. This paper investigates temporal variability in the position of the SACCF north of South Georgia that is likely to have an effect on the South Georgia ecosystem by contributing to the variability in local krill abundance. A meridional hydrographic section that crossed the SACCF three times demonstrates that the SACCF is associated with a geopotential anomaly of 4.5 J kg-1 in the eastern Scotia Sea. A high resolution (1/4°×1/4°) map of historical geopotential anomaly shows the mean position of the SACCF retroflection north of South Georgia to be at 36°W, 400 km further east than in previous work. It also reveals temporal variability associated with the SACCF in the South Georgia region. A near-surface drifter provides evidence for variability in the western extent of the SACCF north of South Georgia and for the presence of eddies in the region. Output from a 3-year (1993–1995) high frequency wind forced run of the eddy-permitting Ocean Circulation and Climate Advanced Modelling project (OCCAM) model, used to investigate the frontal variability, shows two periods of anomalous westward extent of the SACCF north of South Georgia and associated eddy-shedding. The SACCF variability affects the near-surface transport of passive drifters into the region with implications for the South Georgia ecosystem

Induction of PEP Carboxylase and Crassulacean Acid Metabolism by Gibberellic Acid in Mesembryanthemum crystallinum

The induction of Crassulacean acid metabolism in Mesembryanthemum crystallinum was investigated in response to foliar application of gibberellic acid (GA). After 5 weeks of treatment, GA-treated plants showed 1.7- to almost a 4-fold increase of phosphoenolpyruvate carboxylase (PEPcase) activity with a concomitant increase in acid metabolism when compared to control plants. Immunoblot analysis indicated an increase in the PEPcase protein similar to that of salt treatment while Rubisco did not show a similar rise. The results indicate that exogenously applied GA accelerates plant developmental expression of PEPcase and Crassulacean acid metabolism in M. crystallinum

Development of a prototype blood fractionation cartridge for plasma analysis by paper spray mass spectrometry

Drug monitoring of biofluids is often time consuming and prohibitively expensive. Analysis of dried blood spots offers advantages, such as reduced sample volume, but depends on extensive sample preparation and the presence of a trained lab technician. Paper spray mass spectrometry allows rapid analysis of small molecules from blood spots with minimal sample preparation, however, plasma is often the preferred matrix for bioanalysis. Plasma spots can be analyzed by paper spray MS, but a centrifugation step to isolate the plasma is required. We demonstrate here the development of a paper spray cartridge containing a plasma fractionation membrane to perform automatic on-cartridge plasma fractionation from whole blood samples. Three commercially available blood fractionation membranes were evaluated based on: 1) accuracy of drug concentration determination in plasma, and 2) extent of cell lysis and/or penetration. The accuracy of drug concentration determination was quantitatively determined using high performance liquid chromatography–mass spectrometry (HPLC–MS). While the fractionation membranes were capable of yielding plasma samples with low levels of cell lysis, the membranes did exhibit drug binding to varying degrees, as indicated by a decrease in the drug concentration relative to plasma obtained by centrifugation. Using the membrane exhibiting the lowest binding, we developed a composite paper spray cartridge incorporating the selected fractionation membrane. Quantitative analysis of the plasma samples by paper spray MS yielded results similar to those found with HPLC–MS, but without the need for offline extraction or chromatography

Analysis of Biofluids by Paper Spray Mass Spectrometry: Advances and Challenges

Abstract Paper spray MS is part of a cohort of ambient ionization or direct analysis methods that seek to analyze complex samples without prior sample preparation. Extraction and electrospray ionization occur directly from the paper substrate upon which a dried matrix spot is stored. Paper spray MS is capable of detecting drugs directly from dried blood, plasma and urine spots at the low ng/ml to pg/ml levels without sample preparation. No front end separation is performed, so MS/MS or high-resolution MS is required. Here, we discuss paper spray methodology, give a comprehensive literature review of the use of paper spray MS for bioanalysis, discuss technological advancements and variations on this technique and discuss some of its limitations

Supporting Live Development of SOAP and CORBA Servers

We present middleware for a Server Development Environment that facilitates live development of SOAP and CORBA servers. As the underlying implementation platform, we use JPie, a tightly integrated programming environment for live software construction of Java applications. JPie provides dynamic classes whose signature and implementation can be modified at run time, with changes taking effect immediately upon existing instances of the class. We extend this model by automating the server deployment process, allowing developers to devote their full attention to the implementation of server logic. Moreover, the live development model enables the construction of server applications while they are running, connected, and communicating with clients. Combined with our Client Development Environment [1], these features facilitate the live, simultaneous construction of both the client and server applications

Computational approach to the Schottky problem

We present a computational approach to the classical Schottky problem based on Fay's trisecant identity for genus $g\geq 4$. For a given Riemann matrix $\mathbb{B}\in\mathbb{H}^{g}$, the Fay identity establishes linear dependence of secants in the Kummer variety if and only if the Riemann matrix corresponds to a Jacobian variety as shown by Krichever. The theta functions in terms of which these secants are expressed depend on the Abel maps of four arbitrary points on a Riemann surface. However, there is no concept of an Abel map for general $\mathbb{B} \in \mathbb{H}^{g}$. To establish linear dependence of the secants, four components of the vectors entering the theta functions can be chosen freely. The remaining components are determined by a Newton iteration to minimize the residual of the Fay identity. Krichever's theorem assures that if this residual vanishes within the finite numerical precision for a generic choice of input data, then the Riemann matrix is with this numerical precision the period matrix of a Riemann surface. The algorithm is compared in genus 4 for some examples to the Schottky-Igusa modular form, known to give the Jacobi locus in this case. It is shown that the same residuals are achieved by the Schottky-Igusa form and the approach based on the Fay identity in this case. In genera 5, 6 and 7, we discuss known examples of Riemann matrices and perturbations thereof for which the Fay identity is not satisfied

Academic Resilience of Athletic Training Students During COVID-19 Pandemic

OBJECTIVE (1) To describe resilience in athletic training students enrolled in professional coursework during the spring 2020 semester, and (2) to determine the association between resilience and academic performance during the spring 2020 semester. MAIN OUTCOME MEASURESDescriptive statistics for GPA were calculated for Fall 2019, Spring 2020, cumulative Fall 2019, cumulative Spring 2020 (ie., current), change in cumulative GPA, and ARS-30 total score. The primary analysis was a Pearson correlation between change in cumulative GPA and ARS-30 total score. A secondary analysis was conducted to evaluate change in cumulative Fall 2019 and Spring 2020 GPA with a paired t-test. Cohen’s d effect size was calculated for the paired t-test. Alpha level was set at 0.05

A Dark Spot on a Massive White Dwarf

We present the serendipitous discovery of eclipse-like events around the massive white dwarf SDSS J152934.98+292801.9 (hereafter J1529+2928). We selected J1529+2928 for time-series photometry based on its spectroscopic temperature and surface gravity, which place it near the ZZ Ceti instability strip. Instead of pulsations, we detect photometric dips from this white dwarf every 38 minutes. Follow-up optical spectroscopy observations with Gemini reveal no significant radial velocity variations, ruling out stellar and brown dwarf companions. A disintegrating planet around this white dwarf cannot explain the observed light curves in different filters. Given the short period, the source of the photometric dips must be a dark spot that comes into view every 38 min due to the rotation of the white dwarf. Our optical spectroscopy does not show any evidence of Zeeman splitting of the Balmer lines, limiting the magnetic field strength to B<70 kG. Since up to 15% of white dwarfs display kG magnetic fields, such eclipse-like events should be common around white dwarfs. We discuss the potential implications of this discovery on transient surveys targeting white dwarfs, like the K2 mission and the Large Synoptic Survey Telescope.Comment: ApJ Letters, in pres