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Membraneless seawater desalination
Disclosed are microfluidic devices and systems for the desalination of water. The devices and systems can include an electrode configured to generate an electric field gradient in proximity to an intersection formed by the divergence of two microfluidic channels from an inlet channel. Under an applied bias and in the presence of a pressure driven flow of saltwater, the electric field gradient can preferentially direct ions in saltwater into one of the diverging microfluidic channels, while desalted water flows into second diverging channel. Also provided are methods of using the devices and systems described herein to decrease the salinity of water.Board of Regents, University of Texas Syste
Super-solar metallicity at the position of the ultra-long GRB130925A
Over the last decade there has been immense progress in the follow-up of
short and long GRBs, resulting in a significant rise in the detection rate of
X-ray and optical afterglows, in the determination of GRB redshifts, and of the
identification of the underlying host galaxies. Nevertheless, our theoretical
understanding on the progenitors and central engines powering these vast
explosions is lagging behind, and a newly identified class of `ultra-long' GRBs
has fuelled speculation on the existence of a new channel of GRB formation. In
this paper we present high signal-to-noise X-shooter observations of the host
galaxy of GRB130925A, which is the fourth unambiguously identified ultra-long
GRB, with prompt gamma-ray emission detected for ~20ks. The GRB line of sight
was close to the host galaxy nucleus, and our spectroscopic observations cover
both this region along the bulge/disk of the galaxy, in addition to a bright
star-forming region within the outskirts of the galaxy. From our broad
wavelength coverage we obtain accurate metallicity and dust-extinction
measurements at both the galaxy nucleus, and an outer star-forming region, and
measure a super-solar metallicity at both locations, placing this galaxy within
the 10-20% most metal-rich GRB host galaxies. Such a high metal enrichment has
implications on the progenitor models of both long and ultra-long GRBs,
although the edge-on orientation of the host galaxy does not allow us to rule
out a large metallicity variation along our line of sight. The spatially
resolved spectroscopic data presented in this paper offer important insight
into variations in the metal and dust abundance within GRB host galaxies. They
also illustrate the need for IFU observations on a larger sample of GRB host
galaxies at varies metallicities to provide a more quantitative view on the
relation between the GRB circumburst and the galaxy-whole properties.Comment: 9 pages, 3 figures, A&A in press, matches published versio
Habitat-based density models of pack-ice seal distribution in the southern Weddell Sea, Antarctica
Climate variability and changes in sea ice dynamics have caused several ice-obligate or krill-dependent populations of marine predators to decline, eliciting concern about their demographic persistence and the indirect ecological consequences that predator depletions may have on marine ecosystems. Pack-ice seals are dominant ice-obligate predators in the Antarctic marine ecosystem, but there is considerable uncertainty about their abundance and population trends. We modelled the density and distribution of pack-ice seals as a function of environmental covariates in the southern Weddell Sea, Antarctica. Our density surface modelling approach used data from aerial surveys of pack-ice seals collected in the 2013/14 austral summer. Crabeater seals Lobo don carcinophaga, the most numerous pack-ice seal we observed, occurred at the highest densities in areas with extensive sea ice near the continental shelf break, but were almost absent in areas of similar sea ice concentration in the southern extent of the Weddell Sea. The highest densities of Weddell seals Leptonychotes weddelli, which were less abundant than crabeater seals within the pack-ice habitat, were predicted to occur over the continental shelf, near the shelf break. The distribution of both seal species broadly corresponded with the distribution and relative abundance of their main prey (Antarctic krill Euphausia superba and Antarctic silverfish Pleuragramma antarctica) obtained from concurrent ecosystem surveys. Ross seals Ommatophoca rossii and leopard seals Hydrurga leptonyx were not detected at all and are apparently rare within the southern Weddell Sea. These results can contribute to biodiversity assessments in the context of marine protected area planning in this region of the Southern Ocean
The warm, the excited, and the molecular gas: GRB 121024A shining through its star-forming galaxy
We present the first reported case of the simultaneous metallicity
determination of a gamma-ray burst (GRB) host galaxy, from both afterglow
absorption lines as well as strong emission-line diagnostics. Using
spectroscopic and imaging observations of the afterglow and host of the
long-duration Swift GRB121024A at z = 2.30, we give one of the most complete
views of a GRB host/environment to date. We observe a strong damped Ly-alpha
absorber (DLA) with a hydrogen column density of log N(HI) = 21.88 +/- 0.10, H2
absorption in the Lyman-Werner bands (molecular fraction of log(f)~ -1.4;
fourth solid detection of molecular hydrogen in a GRB-DLA), the nebular
emission lines H-alpha, H-beta, [O II], [O III] and [N II], as well as metal
absorption lines. We find a GRB host galaxy that is highly star-forming (SFR ~
40 solar masses/yr ), with a dust-corrected metallicity along the line of sight
of [Zn/H]corr = -0.6 +/- 0.2 ([O/H] ~ -0.3 from emission lines), and a
depletion factor [Zn/Fe] = 0.85 +/- 0.04. The molecular gas is separated by 400
km/s (and 1-3 kpc) from the gas that is photoexcited by the GRB. This implies a
fairly massive host, in agreement with the derived stellar mass of
log(M/M_solar ) = 9.9+/- 0.2. We dissect the host galaxy by characterising its
molecular component, the excited gas, and the line-emitting star-forming
regions. The extinction curve for the line of sight is found to be unusually
flat (Rv ~15). We discuss the possibility of an anomalous grain size
distributions. We furthermore discuss the different metallicity determinations
from both absorption and emission lines, which gives consistent results for the
line of sight to GRB 121024A.Comment: 20 pages, 11 figures, accepted by MNRA
The optical identifcation of events with poorly defined locations: The case of the Fermi GBM GRB140801A
We report the early discovery of the optical afterglow of gamma-ray burst
(GRB) 140801A in the 137 deg 3- error-box of the Fermi Gamma-ray
Burst Monitor (GBM). MASTER is the only observatory that automatically react to
all Fermi alerts. GRB 140801A is one of the few GRBs whose optical counterpart
was discovered solely from its GBM localization. The optical afterglow of GRB
140801A was found by MASTER Global Robotic Net 53 sec after receiving the
alert, making it the fastest optical detection of a GRB from a GBM error-box.
Spectroscopy obtained with the 10.4-m Gran Telescopio Canarias and the 6-m BTA
of SAO RAS reveals a redshift of . We performed optical and
near-infrared photometry of GRB 140801A using different telescopes with
apertures ranging from 0.4-m to 10.4-m. GRB 140801A is a typical burst in many
ways. The rest-frame bolometric isotropic energy release and peak energy of the
burst is erg and
keV, respectively, which is consistent with the
Amati relation. The absence of a jet break in the optical light curve provides
a lower limit on the half-opening angle of the jet deg. The
observed is consistent with the limit derived from the
Ghirlanda relation. The joint Fermi GBM and Konus-Wind analysis shows that GRB
140801A could belong to the class of intermediate duration. The rapid detection
of the optical counterpart of GRB 140801A is especially important regarding the
upcoming experiments with large coordinate error-box areas.Comment: in press MNRAS, 201
The mysterious optical afterglow spectrum of GRB140506A at z=0.889
Context. Gamma-ray burst (GRBs) afterglows probe sightlines to star-forming
regions in distant star-forming galaxies. Here we present a study of the
peculiar afterglow spectrum of the z = 0.889 Swift GRB 140506A. Aims. Our aim
is to understand the origin of the very unusual properties of the absorption
along the line-of-sight. Methods. We analyse spectroscopic observations
obtained with the X-shooter spectrograph mounted on the ESO/VLT at two epochs
8.8 h and 33 h after the burst as well as imaging from the GROND instrument. We
also present imaging and spectroscopy of the host galaxy obtained with the
Magellan telescope. Results. The underlying afterglow appears to be a typical
afterglow of a long-duration GRB. However, the material along the line-of-
sight has imprinted very unusual features on the spectrum. Firstly, there is a
very broad and strong flux drop below 8000 AA (4000 AA in the rest frame),
which seems to be variable between the two spectroscopic epochs. We can
reproduce the flux-drops both as a giant 2175 AA extinction bump and as an
effect of multiple scattering on dust grains in a dense environment. Secondly,
we detect absorption lines from excited H i and He i. We also detect molecular
absorption from CH+ . Conclusions. We interpret the unusual properties of these
spectra as reflecting the presence of three distinct regions along the
line-of-sight: the excited He i absorption originates from an H ii-region,
whereas the Balmer absorption must originate from an associated
photodissociation region. The strong metal line and molecular absorption and
the dust extinction must originate from a third, cooler region along the
line-of-sight. The presence of (at least) three separate regions is reflected
in the fact that the different absorption components have different velocities
relative to the systemic redshift of the host galaxy.Comment: 8 pages, 4 figures. Accepted for publications in A&
Shelf ice-associated cryo-benthos and environmental features
Incidences of cryo-benthic communities beneath ice shelves are rare and recent discoveries. Combined seal- and ROV-borne imagery and novel sampling technologies allowed for a re-assessment and augmentation of earlier findings on a cryo-benthic isopod community (Antarcturus cf. spinacoronatus), being attached head-down to the underside of floating shelf ice at depths of around 80-150m. The shelf ice-associated cryo-benthos was discovered at Drescher Inlet (-72.83667 -19.15300), Riiser-Larsen Ice Shelf (eastern Weddell Sea). The inlet constitutes a 25km long and between 2 and 4km wide crack in the surrounding shelf ice, which is associated with certain environmental features. Here we compile all available local physical, biological, and biogeochemical data and discuss their relevance in the wider regional context for this faunal hotspot. These include data on shelf, sea and platelet ice, seafloor topography, hydrography and water chemistry, as well as associated pelagic and benthic marine life, in particular affinities of the cryo-benthic isopod community to related fauna occurring in nearby seabed communities using molecular barcoding
The evolution of superluminous supernova LSQ14mo and its interacting host galaxy system
We present and analyse an extensive dataset of the superluminous supernova (SLSN) LSQ14mo (z = 0.256), consisting of a multi-colour light curve from-30 d to +70 d in the rest-frame (relative to maximum light) and a series of six spectra from PESSTO covering-7 d to +50 d. This is among the densest spectroscopic coverage, and best-constrained rising light curve, for a fast-declining hydrogen-poor SLSN. The bolometric light curve can be reproduced with a millisecond magnetar model with 4 M⊙ ejecta mass, and the temperature and velocity evolution is also suggestive of a magnetar as the power source. Spectral modelling indicates that the SN ejected 6 M⊙ of CO-rich material with a kinetic energy of 7 × 1051 erg, and suggests a partially thermalised additional source of luminosity between-2 d and +22 d. This may be due to interaction with a shell of material originating from pre-explosion mass loss. We further present a detailed analysis of the host galaxy system of LSQ14mo. PESSTO and GROND imaging show three spatially resolved bright regions, and we used the VLT and FORS2 to obtain a deep (five-hour exposure) spectra of the SN position and the three star-forming regions, which are at a similar redshift. The FORS2 spectrum at + 300 days shows no trace of SN emission lines and we place limits on the strength of [O i] from comparisons with other Ic supernovae. The deep spectra provides a unique chance to investigate spatial variations in the host star-formation activity and metallicity. The specific star-formation rate is similar in all three components,as is the presence of a young stellar population. However, the position of LSQ14mo exhibits a lower metallicity, with 12 + log (O/H) = 8.2 in both the R23 and N2 scales (corresponding to 0.3 Z⊙). We propose that the three bright regions in the host system are interacting, which could induce gas flows triggering star formation in low-metallicity regions. © ESO, 2017
A genome-wide resource for the analysis of protein localisation in Drosophila
The Drosophila genome contains >13000 protein-coding genes, the majority of which remain poorly investigated. Important reasons include the lack of antibodies or reporter constructs to visualise these proteins. Here, we present a genome-wide fosmid library of 10000 GFP-tagged clones, comprising tagged genes and most of their regulatory information. For 880 tagged proteins, we created transgenic lines, and for a total of 207 lines, we assessed protein expression and localisation in ovaries, embryos, pupae or adults by stainings and live imaging approaches. Importantly, we visualised many proteins at endogenous expression levels and found a large fraction of them localising to subcellular compartments. By applying genetic complementation tests, we estimate that about two-thirds of the tagged proteins are functional. Moreover, these tagged proteins enable interaction proteomics from developing pupae and adult flies. Taken together, this resource will boost systematic analysis of protein expression and localisation in various cellular and developmental contexts
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