Proposed design and experimental performance of short two-dimensional curved wall diffusers utilizing suction slots

Design, characteristics, and performance tests of short two dimensional curved wall diffusers using suction slot

Laser-cooling-assisted mass spectrometry

Mass spectrometry is used in a wide range of scientific disciplines including proteomics, pharmaceutics, forensics, and fundamental physics and chemistry. Given this ubiquity, there is a worldwide effort to improve the efficiency and resolution of mass spectrometers. However, the performance of all techniques is ultimately limited by the initial phase-space distribution of the molecules being analyzed. Here, we dramatically reduce the width of this initial phase-space distribution by sympathetically cooling the input molecules with laser-cooled, co-trapped atomic ions, improving both the mass resolution and detection efficiency of a time-of-flight mass spectrometer by over an order of magnitude. Detailed molecular dynamics simulations verify the technique and aid with evaluating its effectiveness. Our technique appears to be applicable to other types of mass spectrometers.Comment: 6 pages, 4 figure

Constraints on Association of Single-pulse Gamma-ray Bursts and Supernovae

We explore the hypothesis, similar to one recently suggested by Bloom and colleagues, that some nearby supernovae are associated with smooth, single-pulse gamma-ray bursts, possibly having no emission above ~ 300 keV. We examine BATSE bursts with durations longer than 2 s, fitting those which can be visually characterized as single-pulse events with a lognormal pulse model. The fraction of events that can be reliably ascertained to be temporally and spectrally similar to the exemplar, GRB 980425 - possibly associated with SN 1998bw - is 4/1573 or 0.25%. This fraction could be as high as 8/1573 (0.5%) if the dimmest bursts are included. Approximately 2% of bursts are morphologically similar to GRB 980425 but have emission above ~ 300 keV. A search of supernova catalogs containing 630 detections during BATSE's lifetime reveals only one burst (GRB 980425) within a 3-month time window and within the total 3-sigma BATSE error radius that could be associated with a type Ib/c supernova. There is no tendency for any subset of single-pulse GRBs to fall near the Supergalactic Plane, whereas SNe of type Ib/c do show this tendency. Economy of hypotheses leads us to conclude that nearby supernovae generally are not related to smooth, single-pulse gamma-ray bursts.Comment: 25 pages, 5 figure

Global Forces in Eruptive Solar Flares: The Lorentz force Acting on the Solar Atmosphere and the Solar Interior

We compute the change in the Lorentz force integrated over the outer solar atmosphere implied by observed changes in vector magnetograms that occur during large, eruptive solar flares. This force perturbation should be balanced by an equal and opposite force perturbation acting on the solar photosphere and solar interior. The resulting expression for the estimated force change in the solar interior generalizes the earlier expression presented by Hudson, Fisher and Welsch (CS-383, ASP, 221, 2008), providing horizontal as well as vertical force components, and provides a more accurate result for the vertical component of the perturbed force. We show that magnetic eruptions should result in the magnetic field at the photosphere becoming more horizontal, and hence should result in a downward (towards the solar interior) force change acting on the photosphere and solar interior, as recently argued from an analysis of magnetogram data by Wang and Liu (Astrophys. J. Lett. 716, L195, 2010). We suggest the existence of an observational relationship between the force change computed from changes in the vector magnetograms, the outward momentum carried by the ejecta from the flare, and the properties of the helioseismic disturbance driven by the downward force change. We use the impulse driven by the Lorentz-force change in the outer solar atmosphere to derive an upper limit to the mass of erupting plasma that can escape from the Sun. Finally, we compare the expected Lorentz-force change at the photosphere with simple estimates from flare-driven gasdynamic disturbances and from an estimate of the perturbed pressure from radiative backwarming of the photosphere in flaring conditions.Comment: 23 pages, 6 figures. Accepted by Solar Physics, Nov. 11, 201

First ALMA Observation of a Solar Plasmoid Ejection from an X-ray Bright Point

Eruptive phenomena such as plasmoid ejections or jets are an important feature of solar activity with the potential for improving our understanding of the dynamics of the solar atmosphere. Such ejections are often thought to be signatures of the outflows expected in regions of fast magnetic reconnection. The 304 A EUV line of Helium, formed at around 10^5 K, is found to be a reliable tracer of such phenomena, but the determination of physical parameters from such observations is not straightforward. We have observed a plasmoid ejection from an X-ray bright point simultaneously at millimeter wavelengths with ALMA, at EUV wavelengths with AIA, in soft X-rays with Hinode/XRT. This paper reports the physical parameters of the plasmoid obtained by combining the radio, EUV and X-ray data. As a result, we conclude that the plasmoid can consist either of (approximately) isothermal 10^5 K plasma that is optically thin at 100 GHz, or else a 10^4 K core with a hot envelope. The analysis demonstrates the value of the additional temperature and density constraints that ALMA provides, and future science observations with ALMA will be able to match the spatial resolution of space-borne and other high-resolution telescopes.Comment: 10 page, 5 figures, accepted for publication in Astrophysical Journal Letter. The movie can be seen at the following link: http://hinode.nao.ac.jp/user/shimojo/data_area/plasmoid/movie5.mp

Space-based geoengineering: challenges and requirements

The prospect of engineering the Earth's climate (geoengineering) raises a multitude of issues associated with climatology, engineering on macroscopic scales, and indeed the ethics of such ventures. Depending on personal views, such large-scale engineering is either an obvious necessity for the deep future, or yet another example of human conceit. In this article a simple climate model will be used to estimate requirements for engineering the Earth's climate, principally using space-based geoengineering. Active cooling of the climate to mitigate anthropogenic climate change due to a doubling of the carbon dioxide concentration in the Earth's atmosphere is considered. This representative scenario will allow the scale of the engineering challenge to be determined. It will be argued that simple occulting discs at the interior Lagrange point may represent a less complex solution than concepts for highly engineered refracting discs proposed recently. While engineering on macroscopic scales can appear formidable, emerging capabilities may allow such ventures to be seriously considered in the long term. This article is not an exhaustive review of geoengineering, but aims to provide a foretaste of the future opportunities, challenges, and requirements for space-based geoengineering ventures

Deconvolution of directly precipitating and trap-precipitating electrons in solar flare hard x-rays. III.Yohkoh hard x-ray telescope data analysis

We analyze the footpoint separation d and flux asymmetry A of magnetically conjugate double footpoint sources in hard X-ray images from the Yohkoh Hard X-Ray Telescope (HXT). The data set of 54 solar flares includes all events simultaneously observed with the Compton Gamma Ray Observatory (CGRO) in high time resolution mode. From the CGRO data we deconvolved the direct-precipitation and trap-precipitation components previously (in Paper II). Using the combined measurements from CGRO and HXT, we develop an asymmetric trap model that allows us to quantify the relative fractions of four different electron components, i.e., the ratios of direct-precipitating (q_P1, q_P2) and trap-precipitating electrons (q_T1, q_T2) at both magnetically conjugate footpoints. We find mean ratios of q_P1=0.14+/-0.06, q_P2=0.26+/-0.10, and q_T=q_T1+q_T2=0.60+/-0.13. We assume an isotropic pitch-angle distribution at the acceleration site and double-sided trap precipitation (q_T2/q_T1=q_P2/q_P1) to determine the conjugate loss-cone angles (alpha_1=42^deg+/-11^deg and alpha_2=52^deg+/-10^deg) and magnetic mirror ratiosat both footpoints (R_1=1.6,...,4.0 and R_2=1.3,...,2.5). From the relative displacement of footpoint sources we also measure altitude differences of hard X-ray emission at different energies, which are found to decrease systematically with higher energies, with a statistical height difference of h_Lo-h_M1=980+/-250 km and h_M1-h_M2=310+/-300 km between the three lower HXT energy channels (Lo, M1, M2

The O(3P) and N(4S) density measurement at 225 km by ultraviolet absorption and fluorescence in the Apollo-Soyuz test project

The densities of O(3P) and N(4S) at 225 km were determined during the Apollo Soyuz Test Project by a resonance absorption/fluorescence technique in which OI and NI line radiation produced and collimated on board the Apollo was reflected from the Soyuz back to the Apollo for spectral analysis. The two spacecraft maneuvered so that a range of observation angles of plus or minus 15 deg with respect to the normal to the orbital velocity vector was scanned. The measurements were made at night on two consecutive orbits at spacecraft separations of 150 and 500 m. The resulting relative counting rates as function of observation angle were compared to calculated values to determine the oxygen value. This value agrees with mass spectrometric measurements made under similar conditions. The nitrogen value is in good agreement with other measurements and suggests a smaller diurnal variation than is predicted by present models

Millet agriculture dispersed from Northeast China to the Russian Far East: integrating archaeology, genetics, and linguistics

Broomcorn and foxtail millets were being cultivated in the West Liao River basin in Northeast China by at least the sixth millennium BCE. However, when and how millet agriculture spread from there to the north and east remains poorly understood. Here, we trace the dispersal of millet agriculture from Northeast China to the Russian Far East and weigh demic against cultural diffusion as mechanisms for that dispersal. We compare two routes for the spread of millet into the Russian Far East discussed in previous research—an inland route across Manchuria, and a coastal/inland route initially following the Liaodong Peninsula and Yalu River—using an archaeological dataset including millet remains, pottery, stone tools, spindle whorls, jade and figurines. We then integrate the archaeological evidence with linguistic and genetic findings in an approach we term ‘triangulation’. We conclude that an expansion of agricultural societies in Northeast China during the Middle to Late Hongshan (4000–3000 BCE) coincided with the arrival of millet cultivation in eastern Heilongjiang and the Primorye province of the Russian Far East. Our findings support the inland, Manchuria route for the dispersal of millet to the Primorye and suggest that, as well as long-distance cultural exchange, demic diffusion was also involved. Our results are broadly compatible with the farming/language dispersal hypothesis and consistent with a link between the spread of millet farming and proto-Tungusic, the language ancestral to the contemporary Tungusic languages, in late Neolithic Northeast Asia. © 2020 The Author