2,693 research outputs found
Sea spray fluxes from the southwest coast of the United Kingdom-Dependence on wind speed and wave height
Fluxes of sea spray aerosols were measured with the eddy covariance technique from the Penlee Point Atmospheric Observatory (PPAO) on the southwest coast of the United Kingdom over several months from 2015 to 2017. Two different fast-responding aerosol instruments were employed: an ultra-fine condensation particle counter (CPC) that detects aerosols with a radius above ca. 1.5 nm and a compact lightweight aerosol spectrometer probe (CLASP) that provides a size distribution between ca. 0.1 and 6 µm. The measured sea spray emission fluxes essentially all originated from the shallow waters upwind, rather than from the surf zone/shore break. Fluxes from the CPC and from the CLASP (integrated over all sizes) were generally comparable, implying a reasonable closure in the aerosol number flux. Compared to most previous observations over the open ocean, at the same wind speed the mean sea spray number fluxes at PPAO are much greater. Significant wave height and wave Reynolds numbers explain more variability in sea spray fluxes than wind speed does, implying that enhanced wave breaking resulting from shoaling in shallow coastal waters is a dominant control on sea spray emission. Comparisons between two different wind sectors (open water vs. fetch-limited Plymouth Sound) and between two sets of sea states (growing vs. falling seas) further confirm the importance of wave characteristics on sea spray fluxes. These results suggest that spatial variability in wave characteristics need to be taken into account in predictions of coastal sea spray productions and also aerosol loading
Optical Images and Source Catalog of AKARI North Ecliptic Pole Wide Survey Field
We present the source catalog and the properties of the , and
band images obtained to support the {\it AKARI} North Ecliptic Pole Wide
(NEP-Wide) survey. The NEP-Wide is an {\it AKARI} infrared imaging survey of
the north ecliptic pole covering a 5.8 deg area over 2.5 -- 6 \micron
wavelengths. The optical imaging data were obtained at the Maidanak Observatory
in Uzbekistan using the Seoul National University 4k 4k Camera on the
1.5m telescope. These images cover 4.9 deg where no deep optical imaging
data are available. Our , and band data reach the depths of
23.4, 23.1, and 22.3 mag (AB) at 5, respectively. The
source catalog contains 96,460 objects in the band, and the astrometric
accuracy is about 0.15\arcsec at 1 in each RA and Dec direction.
These photometric data will be useful for many studies including identification
of optical counterparts of the infrared sources detected by {\it AKARI},
analysis of their spectral energy distributions from optical through infrared,
and the selection of interesting objects to understand the obscured galaxy
evolution.Comment: 39 pages, 12 figure
Air-sea transfer of gas phase controlled compounds
Gases in the atmosphere/ocean have solubility that spans several orders of magnitude. Resistance in the molecular sublayer on the waterside limits the air-sea exchange of sparingly soluble gases such as SF6 and CO2. In contrast, both aerodynamic and molecular diffusive resistances on the airside limit the exchange of highly soluble gases (as well as heat). Here we present direct measurements of air-sea methanol and acetone transfer from two open cruises: the Atlantic Meridional Transect in 2012 and the High Wind Gas Exchange Study in 2013. The transfer of the highly soluble methanol is essentially completely airside controlled, while the less soluble acetone is subject to both airside and waterside resistances. Both compounds were measured concurrently using a proton-transfer-reaction mass spectrometer, with their fluxes quantified by the eddy covariance method. Up to a wind speed of 15 m s-1, observed air-sea transfer velocities of these two gases are largely consistent with the expected near linear wind speed dependence. Measured acetone transfer velocity is ~30% lower than that of methanol, which is primarily due to the lower solubility of acetone. From this difference we estimate the "zero bubble" waterside transfer velocity, which agrees fairly well with interfacial gas transfer velocities predicted by the COARE model. At wind speeds above 15 m s-1, the transfer velocities of both compounds are lower than expected in the mean. Air-sea transfer of sensible heat (also airside controlled) also appears to be reduced at wind speeds over 20 m s-1. During these conditions, large waves and abundant whitecaps generate large amounts of sea spray, which is predicted to alter heat transfer and could also affect the air-sea exchange of soluble trace gases. We make an order of magnitude estimate for the impacts of sea spray on air-sea methanol transfer
Supermassive Black Hole Mass Functions at Intermediate Redshifts from Spheroid and AGN Luminosity Functions
Redshift evolution of supermassive black hole mass functions (BHMFs) is
investigated up to z ~ 1. BHMFs at intermediate redshifts are calculated in two
ways. One way is from early-type galaxy luminosity functions (LFs); we assume
an M_BH - L_sph correlation at a redshift by considering a passive evolution of
L_sph in the local relationship. The resultant BHMFs (spheroid-BHMFs) from LFs
of red sequence galaxies indicates a slight decrease of number density with
increasing redshift at M_BH > 10^{7.5-8} M_solar. Since a redshift evolution in
slope and zeropoint of the M_BH - L_sph relation is unlikely to be capable of
making such an evolution in BHMF, the evolution of the spheroid-BHMFs is
perhaps due mainly to the decreasing normalization in the galaxy LFs. We also
investigate how spheroid-BHMFs are affected by uncertainties existing in the
derivation in detail. The other way of deriving a BHMF is based on the
continuity equation for number density of SMBHs and LFs of active galactic
nucleus (AGN). The resultant BHMFs (AGN-BHMFs) show no clear evolution out to z
= 1 at M_BH > 10^8 M_solar, but exhibit a significant decrease with redshift in
the lower mass range. Comparison of the spheroid-BHMFs with the AGN-BHMFs
suggests that at M_BH > 10^{8} M_solar, the spheroid-BHMFs are broadly
consistent with the AGN-BHMFs out to z ~ 1. The agreement between the
spheroid-BHMFs and the AGN-BHMFs appears to support that most of the SMBHs are
already hosted by massive spheroids at z ~ 1 and they evolve without
significant mass growth since then.Comment: 13 pages, accepted for publication in MNRA
The Rise of Massive Red Galaxies: the color-magnitude and color-stellar mass diagrams for z < ~2 from the MUltiwavelength Survey by Yale-Chile (MUSYC)
We present the color-magnitude and color-stellar mass diagrams for galaxies
with z_phot < ~2, based on a K < 22 (AB) catalog of the Extended Chandra Deep
Field South (ECDFS) from the MUltiwavelength Survey by Yale-Chile (MUSYC). Our
main sample of 7840 galaxies contains 1297 M_* > 10^11 M_Sol galaxies in the
range 0.2 < z_phot < 1.8. We show empirically that this catalog is
approximately complete for M_* > 10^11 M_Sol galaxies for z_phot < 1.8. For
this mass-limited sample, we show that the locus of the red sequence
color-stellar mass relation evolves as Del(u-r) ~ (-0.44+/-0.02) z_phot for
z_phot ~1.3, however, we are no longer able to reliably
distinguish red and blue subpopulations from the observed color distribution;
we show that this would require much deeper near infrared data. At 1.5 < z_phot
10^11 M_Sol galaxies is ~50% of the
local value, with a red fraction of ~33%. Making a parametric fit to the
observed evolution, we find n_tot(z) ~ (1+z_phot)^(-0.52+/-0.12(+/-0.20)). We
find stronger evolution in the red fraction: f_red(z) ~
(1+z_phot)^(-1.17+/-0.18(+/-0.21)). Through a series of sensitivity analyses,
we show that the most important sources of systematic error are: 1. systematic
differences in the analysis of the z~0 and z>>0 samples; 2. systematic effects
associated with details of the photometric redshift calculation; and 3.
uncertainties in the photometric calibration. With this in mind, we show that
our results based on photometric redshifts are consistent with a completely
independent analysis which does not require redshift information for individual
galaxies. Our results suggest that, at most, 1/5 of local red sequence galaxies
with M_* >10^11 M_Sol were already in place at z ~ 2.Comment: Accepted for publication in ApJ. 31 pages in emulateapj format; 18
figues (14 in main text). Additional online data available through
http://www.strw.leidenuniv.nl/~ent
Mass-dependent evolution of the relation between supermassive black hole mass and host spheroid mass since z ~ 1
We investigate the evolution of supermassive black hole mass (M_BH) and the
host spheroid mass (M_sph) in order to track the history of the M_BH-M_sph
relationship. The typical mass increase of M_BH is calculated by a continuity
equation and accretion history, which is estimated from the active galactic
nucleus (AGN) luminosity function. The increase in M_sph is also calculated by
using a continuity equation and a star formation model, which uses
observational data for the formation rate and stellar mass function. We find
that the black hole to spheroid mass ratio is expected to be substantially
unchanged since z~1.2 for high mass objects (M_BH>10^8.5M_SUN and
M_sph>10^11.3M_SUN). In the same redshift range, the spheroid mass is found to
increase more rapidly than the black hole mass if M_sph>10^11M_SUN. The
proposed mass-dependent model is consistent with the current available
observational data in the M_BH-M_sph diagram.Comment: 15 pages, 8 figures, accepted to MNRA
Galaxy evolution by color-log(n) type since redshift unity in the Hubble Ultra Deep Field
We explore the use of the color-log(n) plane (where n is the global Sersic
index) as a tool for subdividing the high redshift galaxy population in a
physically-motivated manner. Using a series of volume-limited samples out to
z=1.5 in the Hubble Ultra Deep Field (UDF) we confirm the correlation between
color-log(n) plane position and visual morphology observed locally and in other
high redshift studies in the color and/or structure domain. Via comparison to a
low redshift sample from the Millennium Galaxy Catalogue we quantify evolution
by color-log(n) type, accounting separately for the specific selection and
measurement biases against each. Specifically, we measure decreases in B-band
surface brightness of 1.57 +/- 0.22 mag/sq.arcsec and 1.65 +/- 0.22
mag/sq.arcsec for `blue, diffuse' and `red, compact' galaxies respectively
between redshift unity and the present day.Comment: 12 pages, 6 figures, to be published in A&A (accepted 29/10/08
Increased use of malaria rapid diagnostic tests improves targeting of anti-malarial treatment in rural Tanzania: implications for nationwide rollout of malaria rapid diagnostic tests.
ABSTRACT: BACKGROUND: The World Health Organization recommends parasitological confirmation of all malaria cases. Tanzania is implementing a phased rollout of malaria rapid diagnostic tests (RDTs) for routine use in all levels of care as one strategy to increase parasitological confirmation of malaria diagnosis. This study was carried out to evaluated artemisinin combination therapy (ACT) prescribing patterns in febrile patients with and without uncomplicated malaria in one pre-RDT implementation and one post-RDT implementation area. METHODS: A cross-sectional health facility surveys was conducted during high and low malaria transmission seasons in 2010 in both areas. Clinical information and a reference blood film on all patients presenting for an initial illness consultation were collected. Malaria was defined as a history of fever in the past 48 hours and microscopically confirmed parasitaemia. Routine diagnostic testing was defined as RDT or microscopy ordered by the health worker and performed at the health facility as part of the health worker-patient consultation. Correct diagnostic testing was defined as febrile patient tested with RDT or microscopy. Over-testing was defined as a febrile patient tested with RDT or microscopy. Correct treatment was defined as patient with malaria prescribed ACT. Over-treatment was defined as patient without malaria prescribed ACT. RESULTS: A total of 1,247 febrile patients (627 from pre-implementation area and 620 from post-implementation area) were included in the analysis. In the post-RDT implementation area, 80.9% (95% CI, 68.2-89.3) of patients with malaria received recommended treatment with ACT compared to 70.3% (95% CI, 54.7-82.2) of patients in the pre-RDT implementation area. Correct treatment was significantly higher in the post-implementation area during high transmission season (85.9% (95%CI, 72.0-93.6) compared to 58.3% (95%CI, 39.4-75.1) in pre-implementation area (p=0.01). Over-treatment with ACT of patients without malaria was less common in the post-RDT implementation area (20.9%; 95% CI, 14.7-28.8) compared to the pre-RDT implementation area (45.8%; 95% CI, 37.2-54.6) (p<0.01) in high transmission. The odds of overtreatment was significantly lower in post- RDT area (adjusted Odds Ratio (OR: 95%CI) 0.57(0.36-0.89); and much higher with clinical diagnosis adjusted OR (95%CI) 2.24(1.37-3.67) CONCLUSION: Implementation of RDTs increased use of RDTs for parasitological confirmation and reduced over-treatment with ACT during high malaria transmission season in one area in Tanzania. Continued monitoring of the national RDT rollout will be needed to assess whether these changes in case management practices will be replicated in other areas and sustained over time. Additional measures (such as refresher trainings, closer supervisions, etc) may be needed to improve ACT targeting during low transmission seasons
Optical Magnetometry
Some of the most sensitive methods of measuring magnetic fields utilize
interactions of resonant light with atomic vapor. Recent developments in this
vibrant field are improving magnetometers in many traditional areas such as
measurement of geomagnetic anomalies and magnetic fields in space, and are
opening the door to new ones, including, dynamical measurements of bio-magnetic
fields, detection of nuclear magnetic resonance (NMR), magnetic-resonance
imaging (MRI), inertial-rotation sensing, magnetic microscopy with cold atoms,
and tests of fundamental symmetries of Nature.Comment: 11 pages; 4 figures; submitted to Nature Physic
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