1,080 research outputs found
Beacons into the Cosmic Dark Ages: Boosted transmission of Ly from UV bright galaxies at
Recent detections of Lyman alpha (Ly) emission from galaxies
were somewhat unexpected given a dearth of previous non-detections in this era
when the intergalactic medium (IGM) is still highly neutral. But these
detections were from UV bright galaxies, which preferentially live in
overdensities which reionize early, and have significantly Doppler-shifted
Ly line profiles emerging from their interstellar media (ISM), making
them less affected by the global IGM state. Using a combination of reionization
simulations and empirical ISM models we show, as a result of these two effects,
UV bright galaxies in overdensities have higher transmission through
the IGM than typical field galaxies, and this boosted transmission is
enhanced as the neutral fraction increases. The boosted transmission is not
sufficient to explain the observed high Ly fraction of galaxies (Stark et al. 2017), suggesting Ly emitted by
these galaxies must be stronger than expected due to enhanced production and/or
selection effects. Despite the bias of UV bright galaxies to reside in
overdensities we show Ly observations of such galaxies can accurately
measure the global neutral hydrogen fraction, particularly when Ly from
UV faint galaxies is extinguished, making them ideal candidates for
spectroscopic follow-up into the cosmic Dark Ages.Comment: 6 pages, 5 figures. Accepted for publication in ApJ
An Original HPLC Method with Coulometric Detection to Monitor Hydroxyl Radical Generation via Fenton Chemistry
Hydroxyl radicals (•OH) can be generated via Fenton chemistry catalyzed by transition metals. An in vitro Fenton system was developed to test both the inhibition and stimulation of •OH formation, by monitoring salicylate aromatic hydroxylation derivatives as markers of •OH production. The reaction was optimized with either iron or copper, and target analytes were determined by means of an original HPLC method coupled to coulometric detection. The method granted good sensitivity and precision, while method applicability was tested on antioxidant compounds with and without chelating properties in different substance to metal ratios. This analytical approach shows how Fenton's reaction can be monitored by HPLC coupled to coulometric detection, as a powerful tool for studying molecules' redox behavior
Pre-Alpine and Alpine deformation at San Pellegrino pass (Dolomites, Italy)
In this work, we present the geological map of the San Pellegrino pass, inserted in the
spectacular scenario of the Dolomiti region (Southern Alps, Italy), at a scale of 1:10.000 and
accompanied by geological cross-sections. The detailed distinction of lithological thin units
allowed to achieve a consistent interpretation of the local structural setting by drawing
brittle and ductile Alpine tectonic deformations. The differential deformation and structural
styles within the geological map are the result of the different rheological nature of volcanic
and sedimentary rocks, as well as of the superimposition of compressional Alpine tectonics
over Permo-Mesozoic extensional tectonic phases, and consequent reactivation of inherited
structures
Het-node2vec: second order random walk sampling for heterogeneous multigraphs embedding
We introduce a set of algorithms (Het-node2vec) that extend the original
node2vec node-neighborhood sampling method to heterogeneous multigraphs, i.e.
networks characterized by multiple types of nodes and edges. The resulting
random walk samples capture both the structural characteristics of the graph
and the semantics of the different types of nodes and edges. The proposed
algorithms can focus their attention on specific node or edge types, allowing
accurate representations also for underrepresented types of nodes/edges that
are of interest for the prediction problem under investigation. These rich and
well-focused representations can boost unsupervised and supervised learning on
heterogeneous graphs.Comment: 20 pages, 5 figure
Inferences on the Timeline of Reionization at z~8 From the KMOS Lens-Amplified Spectroscopic Survey
Detections and non-detections of Lyman alpha (Ly) emission from
galaxies ( Gyr after the Big Bang) can be used to measure the timeline of
cosmic reionization. Of key interest to measuring reionization's mid-stages,
but also increasing observational challenge, are observations at z > 7, where
Ly redshifts to near infra-red wavelengths. Here we present a search
for z > 7.2 Ly emission in 53 intrinsically faint Lyman Break Galaxy
candidates, gravitationally lensed by massive galaxy clusters, in the KMOS
Lens-Amplified Spectroscopic Survey (KLASS). With integration times of ~7-10
hours, we detect no Ly emission with S/N>5 in our sample. We determine
our observations to be 80% complete for 5 spatially and spectrally
unresolved emission lines with integrated line flux erg
s cm. We define a photometrically selected sub-sample of 29
targets at , with a median 5 Ly EW limit of 58A.
We perform a Bayesian inference of the average intergalactic medium (IGM)
neutral hydrogen fraction using their spectra. Our inference accounts for the
wavelength sensitivity and incomplete redshift coverage of our observations,
and the photometric redshift probability distribution of each target. These
observations, combined with samples from the literature, enable us to place a
lower limit on the average IGM neutral hydrogen fraction of at z ~ 8, providing further evidence of rapid reionization
at z~6-8. We show that this is consistent with reionization history models
extending the galaxy luminosity function to , with
low ionizing photon escape fractions, .Comment: Accepted for publication in MNRA
An investigation of bedside laparoscopy in the ICU for cases of non-occlusive mesenteric ischemia
Background: Acute mesenteric ischemia is a rare affection with high related mortality. NOMI presents the most important diagnostic problems and is related with the higher risk of white laparotomy. This study wants to give a contribution for the validation of laparoscopic approach in case of NOMI. Methods: Thirty-two consecutive patients were admitted in last 10 years in ICU of Paolo Giaccone University Hospital of Palermo for AMI. Diagnosis was obtained by multislice CT and selective angiography was done if clinical conditions were permissive. If necrosis was already present or suspected, surgical approach was done. Endovascular or surgical embolectomy was performed when necessary. Twenty NOMI patients underwent medical treatment performing laparoscopy 24 h later to verify the evolution of AMI. A three-port technique was used. In all patients we performed a bed side procedure 48-72 h later in both non-resected and resected group. Results: In 14 up 20 case of NOMI the disease was extended throughout the splanchnic district, in 6 patients it involved the ileum and the colon; after a first look, only 6 patients underwent resection. One patient died 35 h after diagnosis of NOMI. The second look, 48 h later, demonstrated 4 infarction recurrences in the group of resected patients and onset signs of necrosis in 5 patients of non-resected group. A total of 15 resections were performed on 11 patients. Mortality rate was 6/20-30% but it was much higher in resected group (5/11-45,5%). Non-therapeutic laparotomy was avoided in 9/20 patients and in this group mortality rate was 1/9-11%. No morbidity was recorded related to laparoscopic procedure. Conclusions: Laparoscopy could be a feasible and safety surgical approach for management of patient with NOMI. Our retrospective study demonstrates that laparoscopy don't increase morbidity, reduce mortality avoiding non-therapeutic laparotomy
Urgent need for preservation of grapevine (Vitis vinifera L. subsp. vinifera) germplasm from small circum-Sicilian islands as revealed by SSR markers and traditional use investigations
Since the last decades grapevine germplasm is undergoing a process of rapid genetic erosion. This process is of particular concern in minor circum-Sicilian islands, because of the sharp reduction of the cultivated surfaces and the shift of their economy from agriculture to tourism. Aiming at valorising and preserving the surviving varieties we collected 185 accessions during several surveys since 2007. Six nuclear microsatellite markers were used for germplasm characterization, yielding 75 different genetic profiles. We found out that most genetic profiles (39) were not listed in national and international grapevine databases, confirming that the Sicilian minor islands represent underexplored hotspots of genetic diversity for grapevine. We also identified several synonymies, often due to geographic isolation, having 20 varieties at least two names. Conversely, 18 homonyms collectively indicated 34 genetically different accessions. Interviews with farmers provided information on current and past usage, and the origin and type of cultivation practices as well. The study also shows the urgent need for preservation of local grapevine germplasm, due to the disappearance of the elder caretakers of these traditional varieties. For rare germplasm preservation most part of the collected grapevine cultivars were introduced in an ex situ collection field
Detection of Lyman-Alpha Emission From a Triple Imaged z=6.85 Galaxy Behind MACS J2129.4-0741
We report the detection of Ly emission at \AA{} in the
Keck/DEIMOS and \HST WFC3 G102 grism data from a triply-imaged galaxy at
behind galaxy cluster MACS J2129.40741. Combining the
emission line wavelength with broadband photometry, line ratio upper limits,
and lens modeling, we rule out the scenario that this emission line is \oii at
. After accounting for magnification, we calculate the weighted average
of the intrinsic Ly luminosity to be
and Ly equivalent
width to be \AA{}. Its intrinsic UV absolute magnitude at 1600\AA{} is
mag and stellar mass , making
it one of the faintest (intrinsic ) galaxies with
Ly detection at to date. Its stellar mass is in the typical
range for the galaxies thought to dominate the reionization photon budget at
; the inferred Ly escape fraction is high (\%),
which could be common for sub- galaxies with Ly
emission. This galaxy offers a glimpse of the galaxy population that is thought
to drive reionization, and it shows that gravitational lensing is an important
avenue to probe the sub- galaxy population.Comment: Accepted by ApJ Letter
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