Fluorescent biosensors based on silicon nanowires

Nanostructures are arising as novel biosensing platforms promising to surpass current performance in terms of sensitivity, selectivity, and affordability of standard approaches. However, for several nanosensors, the material and synthesis used make the industrial transfer of such technologies complex. Silicon nanowires (NWs) are compatible with Si-based flat architecture fabrication and arise as a hopeful solution to couple their interesting physical properties and surface-to-volume ratio to an easy commercial transfer. Among all the transduction methods, fluorescent probes and sensors emerge as some of the most used approaches thanks to their easy data interpretation, measure affordability, and real-time in situ analysis. In fluorescent sensors, Si NWs are employed as substrate and coupled with several fluorophores, NWs can be used as quenchers in stem-loop configuration, and have recently been used for direct fluorescent sensing. In this review, an overview on fluorescent sensors based on Si NWs is presented, analyzing the literature of the field and highlighting the advantages and drawbacks for each strategy

Dust properties of Lyman break galaxies at z∼3z\sim3

We explore from a statistical point of view the far-infrared (far-IR) and sub-millimeter (sub-mm) properties of a large sample of LBGs (22,000) at z~3 in the COSMOS field. The large number of galaxies allows us to split it in several bins as a function of UV luminosity, UV slope, and stellar mass to better sample their variety. We perform stacking analysis in PACS (100 and 160 um), SPIRE (250, 350 and 500 um) and AzTEC (1.1 mm) images. Our stacking procedure corrects the biases induced by galaxy clustering and incompleteness of our input catalogue in dense regions. We obtain the full IR spectral energy distributions (SED) of subsamples of LBGs and derive the mean IR luminosity as a function of UV luminosity, UV slope, and stellar mass. The average IRX is roughly constant over the UV luminosity range, with a mean of 7.9 (1.8 mag). However, it is correlated with UV slope, and stellar mass. We investigate using a statistically-controlled stacking analysis as a function of (stellar mass, UV slope) the dispersion of the IRX-UVslope and IRX-M* plane. Our results enable us to study the average relation between star-formation rate (SFR) and stellar mass, and we show that our LBG sample lies on the main sequence of star formation at z~3.Comment: Accepted to A&A, 17 Pages, 14 Figures, 2 Table

HerMES: the rest-frame UV emission and a lensing model for the z= 6.34 luminous dusty starburst galaxy HFLS3

We discuss the rest-frame ultraviolet emission from the starbursting galaxy HFLS3 at a redshift of 6.34. The galaxy was discovered in Herschel/SPIRE data due to its red color in the submillimeter wavelengths from 250 to 500 μm. Keck/NIRC2 K s -band adaptive optics imaging data showed two potential near-IR counterparts near HFLS3. Previously, the northern galaxy was taken to be in the foreground at z = 2.1, while the southern galaxy was assumed to be HFLS3's near-IR counterpart. The recently acquired Hubble/WFC3 and Advanced Camera for Surveys (ACS) imaging data show conclusively that both optically bright galaxies are in the foreground at z < 6. A new lensing model based on the Hubble imaging data and the millimeter-wave continuum emission yields a magnification factor of 2.2 ± 0.3, with a 95% confidence upper limit on the magnification of 3.5. When corrected for lensing, the instantaneous star formation rate is 1320 M ☉ yr–1, with the 95% confidence lower limit around 830 M ☉ yr–1. The dust and stellar masses of HFLS3 from the same spectral energy distribution (SED) models are at the level of 3 × 108 M ☉ and ~5 × 1010 M ☉, respectively, with large systematic uncertainties on assumptions related to the SED model. With Hubble/WFC3 images, we also find diffuse near-IR emission about 0.5 arcsec (~3 kpc) to the southwest of HFLS3 that remains undetected in the ACS imaging data. The emission has a photometric redshift consistent with either z ~ 6 or a dusty galaxy template at z ~ 2

A quiescent galaxy at the position of the long GRB 050219A

Long-duration gamma-ray bursts (LGRBs) are produced by the collapse of very massive stars. Due to the short lifetime of their progenitors, LGRBs pinpoint star-forming galaxies. We present here a multi-band search for the host galaxy of the long dark GRB 050219A within the enhanced Swift/XRT error circle. We used spectroscopic observations acquired with VLT/X-shooter to determine the redshift and star-formation rate of the putative host galaxy. We compared the results with the optical/IR spectral energy distribution obtained with different facilities. Surprisingly, the host galaxy is a old and quiescent early-type galaxy at z = 0.211 characterised by an unprecedentedly low specific star-formation rate. It is the first LGRB host to be also an early-type post-starburst galaxy. This is further evidence that GRBs can explode in all kind of galaxies, with the only requirement being an episode of star-formation.Comment: 11 pages, 10 figures, 3 tables; accepted for publication in Astronomy & Astrophysic

Differences in clinical presentation of primary open-angle glaucoma between African and European populations

PURPOSE: Primary open‐angle glaucoma (POAG) has been reported to occur more frequently in Africans, and to follow a more severe course compared to Europeans. We aimed to describe characteristics of POAG presentation and treatment across three ethnic groups from Africa and one from Europe. METHODS: We ascertained 151 POAG patients from South African Coloured (SAC) and 94 South African Black (SAB) ethnicity from a university hospital in South Africa. In Tanzania, 310 patients were recruited from a university hospital and a referral hospital. In the Netherlands, 241 patients of European ancestry were included. All patients were over 35 years old and had undergone an extensive ophthalmic examination. Patients were diagnosed according to the ISGEO criteria. A biogeographic ancestry analysis was performed to estimate the proportion of genetic African ancestry (GAA). RESULTS: The biogeographic ancestry analysis showed that the median proportion of GAA was 97.6% in Tanzanian, 100% in SAB, 34.2% in SAC and 1.5% in Dutch participants. Clinical characteristics at presentation for Tanzanians, SAB, SAC and Dutch participants, respectively: mean age: 63, 57, 66, 70 years (p < 0.001); visual acuity in the worse eye: 1.78, 1.78, 0.3, 0.3 LogMAR (p < 0.001); maximum intraocular pressure of both eyes: 36, 34, 29, 29 mmHg (p (anova)  < 0.001); maximum vertical cup to disc ratio (VCDR) of both eyes: 0.90, 0.90, 0.84, 0.83 (p < 0.001); mean central corneal thickness: 506, 487, 511, 528 μm (p < 0.001). Fourteen percent of Tanzanian patients presented with blindness (<3/60 Snellen) in the better eye in contrast to only 1% in the Dutch. CONCLUSION: In this multi‐ethnic comparative study, Sub‐Saharan Africans present at a younger age with lower visual acuity, higher IOP, larger VCDR, than SAC and Dutch participants. This indicates the more progressive and destructive course in Sub‐Saharan Africans

Environment of the submillimeter-bright massive starburst HFLS3 at z∼z\sim6.34

We describe the search for Lyman-break galaxies (LBGs) near the sub-millimeter bright starburst galaxy HFLS3 at $z$$=$6.34 and a study on the environment of this massive galaxy during the end of reionization.We performed two independent selections of LBGs on images obtained with the \textit{Gran Telescopio Canarias} (GTC) and the \textit{Hubble Space Telescope} (HST) by combining non-detections in bands blueward of the Lyman-break and color selection. A total of 10 objects fulfilling the LBG selection criteria at $z$$>$5.5 were selected over the 4.54 and 55.5 arcmin$^2$ covered by our HST and GTC images, respectively. The photometric redshift, UV luminosity, and the star-formation rate of these sources were estimated with models of their spectral energy distribution. These $z$$\sim$6 candidates have physical properties and number densities in agreement with previous results. The UV luminosity function at $z$$\sim$6 and a Voronoi tessellation analysis of this field shows no strong evidence for an overdensity of relatively bright objects (m$_{F105W}$$<$25.9) associated with \textit{HFLS3}. However, the over-density parameter deduced from this field and the surface density of objects can not excluded definitively the LBG over-density hypothesis. Moreover we identified three faint objects at less than three arcseconds from \textit{HFLS3} with color consistent with those expected for $z$$\sim$6 galaxies. Deeper data are needed to confirm their redshifts and to study their association with \textit{HFLS3} and the galaxy merger that may be responsible for the massive starburst.Comment: 14 pages, 12 figures, accepted for publication in Ap

Mesenchymal stromal cell treatment of donor kidneys during ex-vivo normothermic machine perfusion:A porcine renal autotransplantation study

Normothermic machine perfusion (NMP) of injured kidneys offers the opportunity for interventions to metabolically active organs prior to transplantation. Mesenchymal stromal cells (MSCs) can exert regenerative and anti-inflammatory effects in ischaemia-reperfusion injury. The aims of this study were to evaluate the safety and feasibility of MSC treatment of kidneys during NMP using a porcine auto-transplantation model, and examine potential MSC treatment-associated kidney improvements up to 14 days post transplantation. After 75 minutes of kidney warm ischaemia, four experimental groups of n=7 underwent 14 hours of oxygenated hypothermic machine perfusion. In three groups this was followed by 240 minutes of NMP with infusion of vehicle, ten million porcine or ten million human adipose derived MSCs. All kidneys were auto-transplanted after contralateral nephrectomy. MSC treatment did not affect perfusion haemodynamics during NMP or cause adverse effects at reperfusion, with 100% animal survival. MSCs did not affect plasma creatinine, glomerular filtration rate, neutrophil gelatinase-associated lipocalin concentrations or kidney damage assessed by histology during the 14 days, and MSCs retention was demonstrated in renal cortex. Infusing MSCs during ex vivo NMP of porcine kidneys was safe and feasible. Within the short post- transplant

Physical properties of Herschel selected galaxies in a semi-analytic galaxy formation model

[Abridged] We make use of a semi-analytic cosmological model that includes simple prescriptions for dust attenuation and emission to make predictions for the observable and physical properties of galaxies that may be detected by the recently launched Herschel Space Observatory in deep fields such as GOODS-Herschel. We compare our predictions for differential galaxy number counts in the PACS (100 & 160) and SPIRE (250, 350, and 500 micron) bands with available observations. We find very good agreement with the counts in the PACS bands, for the overall counts and for galaxies binned by redshift at z< 2. At z > 2 our model underpredicts the number of bright galaxies by a factor of ten. The agreement is much worse for all three SPIRE bands, and becomes progressively worse with increasing wavelength. We discuss a number of possible reasons for these discrepancies, and hypothesize that the effect of blending on the observational flux estimates is likely to be the dominant issue. We note that the PACS number counts are relatively robust to changes in the dust emission templates, while the predicted SPIRE number counts are more template dependent. We present quantitative predictions for the relationship between the observed PACS 160 and SPIRE 250 micron fluxes and physical quantities such as halo mass, stellar mass, cold gas mass, star formation rate, and total infrared (IR) luminosity, at different redshifts. We also present quantitative predictions for the correlation between PACS 160 micron flux and the probability that a galaxy has experienced a recent major or minor merger. Although our models predict a strong correlation between these quantities, such that more IR-luminous galaxies are more likely to be merger-driven, we find that more than half of all high redshift IR-luminous galaxies detected by Herschel are able to attain their high star formation rates without enhancement by a merger.Comment: Accepted for publication in MNRA

The Herschel Multi-tiered Extragalactic Survey: HerMES

The Herschel Multi-tiered Extragalactic Survey, HerMES, is a legacy program designed to map a set of nested fields totalling ~380 deg^2. Fields range in size from 0.01 to ~20 deg^2, using Herschel-SPIRE (at 250, 350 and 500 \mu m), and Herschel-PACS (at 100 and 160 \mu m), with an additional wider component of 270 deg^2 with SPIRE alone. These bands cover the peak of the redshifted thermal spectral energy distribution from interstellar dust and thus capture the re-processed optical and ultra-violet radiation from star formation that has been absorbed by dust, and are critical for forming a complete multi-wavelength understanding of galaxy formation and evolution. The survey will detect of order 100,000 galaxies at 5\sigma in some of the best studied fields in the sky. Additionally, HerMES is closely coordinated with the PACS Evolutionary Probe survey. Making maximum use of the full spectrum of ancillary data, from radio to X-ray wavelengths, it is designed to: facilitate redshift determination; rapidly identify unusual objects; and understand the relationships between thermal emission from dust and other processes. Scientific questions HerMES will be used to answer include: the total infrared emission of galaxies; the evolution of the luminosity function; the clustering properties of dusty galaxies; and the properties of populations of galaxies which lie below the confusion limit through lensing and statistical techniques. This paper defines the survey observations and data products, outlines the primary scientific goals of the HerMES team, and reviews some of the early results.Comment: 23 pages, 17 figures, 9 Tables, MNRAS accepte