1,201 research outputs found
Search for CII Emission on Cosmological Scales at Redshift Z~2.6
We present a search for CII emission over cosmological scales at
high-redshifts. The CII line is a prime candidate to be a tracer of star
formation over large-scale structure since it is one of the brightest emission
lines from galaxies. Redshifted CII emission appears in the submillimeter
regime, meaning it could potentially be present in the higher frequency
intensity data from the Planck satellite used to measure the cosmic infrared
background (CIB). We search for CII emission over redshifts z=2-3.2 in the
Planck 545 GHz intensity map by cross-correlating the 3 highest frequency
Planck maps with spectroscopic quasars and CMASS galaxies from the Sloan
Digital Sky Survey III (SDSS-III), which we then use to jointly fit for CII
intensity, CIB parameters, and thermal Sunyaev-Zeldovich (SZ) emission. We
report a measurement of an anomalous emission
Jy/sr at 95% confidence, which
could be explained by CII emission, favoring collisional excitation models of
CII emission that tend to be more optimistic than models based on CII
luminosity scaling relations from local measurements; however, a comparison of
Bayesian information criteria reveal that this model and the CIB & SZ only
model are equally plausible. Thus, more sensitive measurements will be needed
to confirm the existence of large-scale CII emission at high redshifts.
Finally, we forecast that intensity maps from Planck cross-correlated with
quasars from the Dark Energy Spectroscopic Instrument (DESI) would increase our
sensitivity to CII emission by a factor of 5, while the proposed Primordial
Inflation Explorer (PIXIE) could increase the sensitivity further.Comment: 15 pages, 11 figures, published in MNRA
Fragmentation and OB Star Formation in High-Mass Molecular Hub-Filament System
Filamentary structures are ubiquitously seen in the interstellar medium. The
concentrated molecular mass in the filaments allows fragmentation to occur in a
shorter timescale than the timescale of the global collapse. Such hierarchical
fragmentation may further assist the dissipation of excessive angular momentum.
It is crucial to resolve the morphology and the internal velocity structures of
the molecular filaments observationally.
We perform 0".5-2".5 angular resolution interferometric observations toward
the nearly face-on OB cluster forming region G33.92+0.11. Observations of
various spectral lines as well as the millimeter dust continuum emission,
consistently trace several 1 pc scale, clumpy molecular arms. Some of the
molecular arms geometrically merge to an inner
3.0\,, 0.6
pc scale central molecular clump, and may directly channel the molecular gas to
the warm (50 K) molecular gas immediately surrounding the centrally
embedded OB stars. The NH spectra suggest a medium turbulence line width
of FWHM2\,km\,s in the central molecular clump, implying a
10 times larger molecular mass than the virial mass. Feedbacks from
shocks and the centrally embedded OB stars and localized (proto)stellar
clusters, likely play a key role in the heating of molecular gas and could lead
to the observed chemical stratification. Although (proto)stellar feedbacks are
already present, G33.92+0.11 chemically appears to be at an early evolutionary
stage given by the low abundance limit of SO observed in this region.Comment: 37 pages, 23 figure
How Low Can You Go? Reducing Frequency and Time Resolution in Current CNN Architectures for Music Auto-tagging
Automatic tagging of music is an important research topic in Music
Information Retrieval and audio analysis algorithms proposed for this task have
achieved improvements with advances in deep learning. In particular, many
state-of-the-art systems use Convolutional Neural Networks and operate on
mel-spectrogram representations of the audio. In this paper, we compare
commonly used mel-spectrogram representations and evaluate model performances
that can be achieved by reducing the input size in terms of both lesser amount
of frequency bands and larger frame rates. We use the MagnaTagaTune dataset for
comprehensive performance comparisons and then compare selected configurations
on the larger Million Song Dataset. The results of this study can serve
researchers and practitioners in their trade-off decision between accuracy of
the models, data storage size and training and inference times.Comment: The 28th European Signal Processing Conference (EUSIPCO
Investigating fragmentation of gas structures in OB cluster-forming molecular clump G33.92+0.11 with 1000 AU resolution observations of ALMA
We report new, 1000 AU spatial resolution observations of 225 GHz dust
continuum emission towards the OB cluster-forming molecular clump G33.92+0.11.
On parsec scales, this molecular clump presents a morphology with several
arm-like dense gas structures surrounding the two central massive (100
) cores. From the new, higher resolution observations, we identified
28 localized, spatially compact dust continuum emission sources, which may be
candidates of young stellar objects. Only one of them is not embedded within
known arm-like (or elongated) dense gas structures. The spatial separations of
these compact sources can be very well explained by Jeans lengths. We found
that G33.92+0.11 may be consistently described by a marginally centrifugally
supported, Toomre unstable accretion flow which is approximately in a face-on
projection. The arm-like overdensities are natural consequence of the Toomre
instability, which can fragment to form young stellar objects in shorter time
scales than the timescale of the global clump contraction. On our resolved
spatial scales, there is not yet evidence that the fragmentation is halted by
turbulence, magnetic field, or stellar feedback.Comment: 24 pages, 18 figures. Accepted to publish on December 04, 2018;
updated to arXiv on December 05, 201
The Local Volume HI Survey: star formation properties
We built a multi-wavelength dataset for galaxies from the Local Volume HI
Survey (LVHIS), which comprises 82 galaxies. We also select a sub-sample of ten
large galaxies for investigating properties in the galactic outskirts. The
LVHIS sample covers nearly four orders of magnitude in stellar mass and two
orders of magnitude in HI mass fraction (fHI). The radial distribution of HI
gas with respect to the stellar disc is correlated with fHI but with a large
scatter. We confirm the previously found correlations between the total HI mass
and star formation rate (SFR), and between HI surface densities and SFR surface
densities beyond R25. However, the former correlation becomes much weaker when
the average surface densities rather than total mass or rate are considered,
and the latter correlation also becomes much weaker when the effect of stellar
mass is removed or controlled. Hence the link between SFR and HI is
intrinsically weak in these regions, consistent with what was found on kpc
scales in the galactic inner regions. We find a strong correlation between the
SFR surface density and the stellar mass surface density, which is consistent
with the star formation models where the gas is in quasi-equilibrium with the
mid-plane pressure. We find no evidence for HI warps to be linked with
decreasing star forming efficiencies.Comment: 31 pages, 20 figures, 4 tables. Accepted for publication at MNRA
Millimeter and submillimeter high angular resolution interferometric observations: dust in the heart of IRAS 18162-2048
The GGD27 complex includes the HH 80-81-80N system, which is one of the most
powerful molecular outflows associated with a high mass star-forming region
observed up to now. This outflow is powered by the star associated with the
source IRAS 18162-2048. Here we report the detection of continuum emission at
sub-arcsec/arcsec resolution with the Submillimeter Array at 1.36mm and
456microns, respectively. We detected dust emission arising from two compact
cores, MM1 and MM2, separated by about 7" (~12000AU in projected distance). MM1
spatially coincides with the powerful thermal radio continuum jet that powers
the very extended molecular outflow, while MM2 is associated with the protostar
that drives the compact molecular outflow recently found in this region.
High angular resolution obervations at 1.36mm show that MM1 is unresolved and
that MM2 splits into two subcomponents separated by ~1". The mass of MM1 is
about 4Msun and it has a size of <300AU. This is consistent with MM1 being
associated with a massive and dense (n(H2)>10^9cm-3) circumstellar dusty disk
surrounding a high-mass protostar, which has not developed yet a compact HII
region. On the other hand, the masses of the two separate components of MM2 are
about 2Msun each. One of these components is a compact core with an
intermediate-mass young protostar inside and the other component is probably a
pre-stellar core.
MM1 is the brigthest source at 1.36mm, while MM2 dominates the emission at
456microns. These are the only (sub)millimeter sources detected in the SMA
observations. Hence, it seems that both sources may contribute significantly to
the bolometric luminosity of the region. Finally, we argue that the
characteristics of these two sources indicate that MM2 is probably in an
earlier evolutionary stage than MM1.Comment: Accepted in AJ (Oct 31, 2010
A rotating molecular disk toward IRAS 18162-2048, the exciting source of HH 80-81
We present several molecular line emission arcsec and subarcsec observations
obtained with the Submillimeter Array (SMA) in the direction of the massive
protostar IRAS 18162-2048, the exciting source of HH 80-81.
The data clearly indicates the presence of a compact (radius~425-850 AU) SO2
structure, enveloping the more compact (radius~150 AU) 1.4 millimeter dust
emission (reported in a previous paper). The emission spatially coincides with
the position of the prominent thermal radio jet which terminates at the HH
80-81 and HH 80N Herbig-Haro objects. Furthermore, the molecular emission is
elongated in the direction perpendicular to the axis of the thermal radio jet,
suggesting a disk-like structure. We derive a total dynamic mass (disk-like
structure and protostar) of 11-15 msun. The SO2 spectral line data also allow
us to constrain the structure temperature between 120-160 K and the volume
density > 2x10^9 cm-3. We also find that such a rotating flattened system could
be unstable due to gravitational disturbances.
The data from C17O line emission show a dense core within this star-forming
region. Additionally, the H2CO and the SO emissions appear clumpy and trace the
disk-like structure, a possible interaction between a molecular core and the
outflows, and in part, the cavity walls excavated by the thermal radio jet.Comment: 13 pages,11 figures. Accepted in the AJ, 07-15-201
A novel semi-fragile forensic watermarking scheme for remote sensing images
Peer-reviewedA semi-fragile watermarking scheme for multiple band images is presented. We propose to embed a mark into remote sensing images applying a tree structured vector quantization approach to the pixel signatures, instead of processing each band separately. The signature of themmultispectral or hyperspectral image is used to embed the mark in it order to detect any significant modification of the original image. The image is segmented into threedimensional blocks and a tree structured vector quantizer is built for each block. These trees are manipulated using an iterative algorithm until the resulting block satisfies a required criterion which establishes the embedded mark. The method is shown to be able to preserve the mark under lossy compression (above a given threshold) but, at the same time, it detects possibly forged blocks and their position in the whole image.Se presenta un esquema de marcas de agua semi-frágiles para múltiples imágenes de banda. Proponemos incorporar una marca en imágenes de detección remota, aplicando un enfoque de cuantización del vector de árbol estructurado con las definiciones de píxel, en lugar de procesar cada banda por separado. La firma de la imagen hiperespectral se utiliza para insertar la marca en el mismo orden para detectar cualquier modificación significativa de la imagen original. La imagen es segmentada en bloques tridimensionales y un cuantificador de vector de estructura de árbol se construye para cada bloque. Estos árboles son manipulados utilizando un algoritmo iteractivo hasta que el bloque resultante satisface un criterio necesario que establece la marca incrustada. El método se muestra para poder preservar la marca bajo compresión con pérdida (por encima de un umbral establecido) pero, al mismo tiempo, detecta posiblemente bloques forjados y su posición en la imagen entera.Es presenta un esquema de marques d'aigua semi-fràgils per a múltiples imatges de banda. Proposem incorporar una marca en imatges de detecció remota, aplicant un enfocament de quantització del vector d'arbre estructurat amb les definicions de píxel, en lloc de processar cada banda per separat. La signatura de la imatge hiperespectral s'utilitza per inserir la marca en el mateix ordre per detectar qualsevol modificació significativa de la imatge original. La imatge és segmentada en blocs tridimensionals i un quantificador de vector d'estructura d'arbre es construeix per a cada bloc. Aquests arbres són manipulats utilitzant un algoritme iteractiu fins que el bloc resultant satisfà un criteri necessari que estableix la marca incrustada. El mètode es mostra per poder preservar la marca sota compressió amb pèrdua (per sobre d'un llindar establert) però, al mateix temps, detecta possiblement blocs forjats i la seva posició en la imatge sencera
Life-Threatening Complication after Extracorporeal Shock Wave Lithotripsy for a Renal Stone: A Hepatic Subcapsular Hematoma
Extracorporeal shock wave lithotripsy (ESWL) has revolutionized the management of urolithiasis since it was first introduced in 1980. ESWL is a well-established, safe and effective therapeutic alternative to surgical treatment for urolithiasis. Complications of ESWL do occur in a small number of patients, and when they do, they typically involve the kidney. We present a case of a young female patient who developed a huge hepatic subcapsular hematoma accompanied by hypovolemic shock after ESWL for a 9 mm stone in the right kidney. The hematoma measured 13×6 cm. Conservative care with no surgical intervention was chosen because there was no evidence of active bleeding on the computed tomography. After conservative therapy, the hematoma was gradually absorbed and the patient was discharged
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