2,563 research outputs found
A population of intermediate-mass black holes in dwarf starburst galaxies up to redshift=1.5
We study a sample of 50,000 dwarf starburst and late-type galaxies
drawn from the COSMOS survey with the aim of investigating the presence of
nuclear accreting black holes (BHs) as those seed BHs from which supermassive
BHs could grow in the early Universe. We divide the sample into five complete
redshift bins up to and perform an X-ray stacking analysis using the
\textit{Chandra} COSMOS-Legacy survey data. After removing the contribution
from X-ray binaries and hot gas to the stacked X-ray emission, we still find an
X-ray excess in the five redshift bins that can be explained by nuclear
accreting BHs. This X-ray excess is more significant for . At higher
redshifts, these active galactic nuclei could suffer mild obscuration, as
indicated by the analysis of their hardness ratios. The average nuclear X-ray
luminosities in the soft band are in the range 10 erg s.
Assuming that the sources accrete at 1\% the Eddington rate, their BH
masses would be 10 M, thus in the intermediate-mass BH
regime, but their mass would be smaller than the one predicted by the
BH-stellar mass relation. If instead the sources follow the correlation between
BH mass and stellar mass, they would have sub-Eddington accreting rates of
10 and BH masses 1-9 10 M. We thus
conclude that a population of intermediate-mass BHs exists in dwarf starburst
galaxies, at least up to =1.5, though their detection beyond the local
Universe is challenging due to their low luminosity and mild obscuration unless
deep surveys are employed.Comment: 10 pages, 7 figures, ApJ in pres
Intermediate-mass black holes in dwarf galaxies out to redshift 2.4 in the Chandra COSMOS Legacy Survey
We present a sample of 40 AGN in dwarf galaxies at redshifts
2.4. The galaxies are drawn from the \textit{Chandra} COSMOS-Legacy survey as
having stellar masses M. Most
of the dwarf galaxies are star-forming. After removing the contribution from
star formation to the X-ray emission, the AGN luminosities of the 40 dwarf
galaxies are in the range erg
s. With 12 sources at , our sample constitutes the
highest-redshift discovery of AGN in dwarf galaxies. The record-holder is
cid\_1192, at and with erg
s. One of the dwarf galaxies has
M and is the least massive galaxy found so far to host an AGN. All
the AGN are of type 2 and consistent with hosting intermediate-mass black holes
(BHs) with masses M and typical Eddington
ratios . We also study the evolution, corrected for completeness, of AGN
fraction with stellar mass, X-ray luminosity, and redshift in dwarf galaxies
out to = 0.7. We find that the AGN fraction for M and erg s is
0.4\% for 0.3 and that it decreases with X-ray luminosity and
decreasing stellar mass. Unlike massive galaxies, the AGN fraction seems to
decrease with redshift, suggesting that AGN in dwarf galaxies evolve
differently than those in high-mass galaxies. Mindful of potential caveats, the
results seem to favor a direct collapse formation mechanism for the seed BHs in
the early Universe.Comment: 16 pages, 10 figures, accepted for publication in MNRA
Enhancement of the luminescence properties of Eu (III) containing paramagnetic saponite clays
In this study, 1,10-phenanthroline molecules were introduced in the interlayer space of a paramagnetic synthetic saponite clay containing both Eu3+ and Gd3+ ions in structural positions. Two samples with different loading of phenanthroline dye were prepared. The resulting hybrid materials possessed improved optical emission properties due to an efficient antenna effect from the phenanthroline to the Eu3+ centers; this effect was demonstrated to be higher than the metal-to-metal Gd3+-Eu3+ energy transfer previously studied. Insights on the relaxometric properties in aqueous solution of the solids after incorporation of the antenna groups were also obtained through NMR relaxometric analyses
Pathogenetic, Clinical, and Prognostic Features of Adult t(4;11)(q21;q23)/MLL-AF4 Positive B-Cell Acute Lymphoblastic Leukemia
Translocation t(4;11)(q21;q23) leading to formation of MLL-AF4 fusion gene is found in about 10% of newly diagnosed B-cell acute lymphoblastic leukemia (ALL) in adult patients. Patients expressing this chromosomal aberration present typical biological, immunophenotypic, and clinical features. This form of leukemia is universally recognized as high-risk leukemia and treatment intensification with allogeneic hematopoietic stem cell transplantation (HSCT) in first complete remission (CR) could be a valid option to improve prognosis, but data obtained from the literature are controversial. In this review, we briefly describe pathogenetic, clinical, and prognostic characteristics of adult t(4;11)(q21;q23)/MLL-AF4 positive ALL and provide a review of the clinical outcome reported by the most important cooperative groups worldwide
Optimisation and validation of a PCR for Antigen Receptor Rearrangement (PARR) assay to detect clonality in canine lymphoid malignancies
PCR for antigen receptor gene rearrangements (PARR) analysis is being increasingly used to assist diagnosis of canine lymphoma. In this study, PARR was carried out on consecutive samples received as part of routine diagnostic practice from 271 patients: 195 with lymphoid malignancies, 53 with reactive conditions and 23 with other neoplasms. Initially, published primer sets were used but later minor primer modifications were introduced and primers were rationalised to give a PARR panel that provides a good compromise between sensitivity and cost. Results were compared to diagnoses made by histology or cytology, coupled with immunophenotyping by flow cytometry or immunohistochemistry where possible. After exclusion of 11 poor quality samples, 230/260 (88%) gave a clear result with 162/163 (99%) of samples classified as clonal and 56/67 (84%) classified as polyclonal giving results concordant with the cytological/histological diagnosis. Among 30 samples with equivocal results, 21 had clonal peaks in a polyclonal background and nine showed little amplification. These were from patients with a range of neoplastic and non-neoplastic conditions emphasising the need to interpret such results carefully in concert with other diagnostic tests. The combination of primer sets used in this study resulted in a robust, highly specific and sensitive assay for detecting clonality
DTPA-Functionalized silica-based monoliths for the removal of transition and lanthanide ions from aqueous phase
Transition and rare-earth metals are essential raw materials used in a wide range of technological applications; moreover, their consumption is often associated with high production of wastes. Therefore, their recycling and recovery from end-of-life products or metal-contaminated aqueous environments is of considerable importance from a circular economy perspective. In our study, synthetic mesoporous silica monoliths, obtained by sol-gel synthesis[1] and functionalized with chelating groups are used for the recovery of metal ions from aqueous matrices (MONO-DTPA). The monoliths were characterized using a multi-technique approach and were tested in the recovery of paramagnetic Gd3+, Cu2+ and Co2+ ions from aqueous solutions, using 1H-NMR relaxometry to evaluate their uptake performance in real time and in simple conditions[2]. Detailed information on the kinetics of the capture process was also extrapolated. Finally, the possibility to regenerate the solid sorbents was evaluated. The modified silica monoliths were able to recover an appreciable amount of both di- and trivalent metal ions. The best results were obtained in the case of Cu2+ after 24 hours of contact, with a recovered amount of 0.29 mmol/g corresponding to 18.48 mg/g (Fig. 1, A).
The capture performance of MONO-DTPA has been shown to be superior to that of natural or synthetic materials commonly used for metal ion removal (Fig 1, B).
[1] V. Miglio, C. Zaccone, C. Vittoni, I. Braschi, E. Buscaroli, G. Golemme, L. Marchese and C. Bisio, Molecules 2021, 26, 1316
[2] S. Marchesi, S. Nascimbene, M. Guidotti, C. Bisio and F. Carniato, Dalton Trans. 2022, 51, 4502–4509
The Xmm-Newton Spectrum of a Candidate Recoiling Supermassive Black Hole: An Elusive Inverted P-Cygni Profile
We present a detailed spectral analysis of new XMM-Newton data of the source CXOC J100043.1+020637, also known as CID-42, detected in the COSMOS survey at z = 0.359. Previous works suggested that CID-42 is a candidate recoiling supermassive black hole (SMBH) showing also an inverted P-Cygni profile in the X-ray spectra at ~6 keV (rest) with an iron emission line plus a redshifted absorption line (detected at 3σ in previous XMM-Newton and Chandra observations). Detailed analysis of the absorption line suggested the presence of ionized material flowing into the black hole at high velocity. In the new long XMM-Newton observation, while the overall spectral shape remains constant, the continuum 2-10 keV flux decrease of ~20% with respect to previous observation and the absorption line is undetected. The upper limit on the intensity of the absorption line is EW \u3c 162 eV. Extensive Monte Carlo simulations show that the nondetection of the line is solely due to variation in the properties of the inflowing material, in agreement with the transient nature of these features, and that the intensity of the line is lower than the previously measured with a probability of 98.8%. In the scenario of CID-42 as a recoiling SMBH, the absorption line can be interpreted as being due to an inflow of gas with variable density that is located in the proximity of the SMBH and recoiling with it. New monitoring observations will be requested to further characterize this line
Giant congenital melanocytic naevi: review of literature
giant congenital pigmented naevi is a great reconstructive challenge for the pediatric and plastic surgeons. due to the increased risk of malignant transformation in such lesions, many procedures have been used to remove giant congenital naevi like dermoabrasion, laser treatment or surgical excision combined with reconstruction through skin expansion or skin grafting; among these, only a complete excision can offer an efficacious treatment. in our centre we use the "tissue expansion" technique in order to achieve a sufficient quantity of normal skin to perform a both staged and radical excision of these giant lesions
Thermal characterisation of a solid waste incinerator by temperature measurements with suction pyrometers
Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.According to the European Waste Directive 2000/76/CE,
temperature of gaseous emissions in the postcombustion zone
of an incinerator is one of the key parameters that has to be
continuously measured and controlled. A bare thermocouple is
generally affected by different physical contributes which make
the gas temperature measurement incorrect.
This paper analyzes the errors that can arise when using a
bare thermocouple, describes principle design and uncertainty
of a suction pyrometer and a method to characterize a waste
incinerator. Results allow a correct thermal characterization of
the plant permitting a better energy management.cs201
Inferring Compton-thick AGN candidates at z>2 with Chandra using the >8 keV restframe spectral curvature
To fully understand cosmic black hole growth we need to constrain the
population of heavily obscured active galactic nuclei (AGN) at the peak of
cosmic black hole growth (1-3). Sources with obscuring column densities
higher than atoms , called Compton-thick
(CT) AGN, can be identified by excess X-ray emission at 20-30 keV, called
the "Compton hump". We apply the recently developed Spectral Curvature (SC)
method to high-redshift AGN (2<z<5) detected with Chandra. This method
parametrizes the characteristic "Compton hump" feature cosmologically
redshifted into the X-ray band at observed energies <10 keV. We find good
agreement in CT AGN found using the SC method and bright sources fit using
their full spectrum with X-ray spectroscopy. In the Chandra deep field south,
we measure a CT fraction of (3/17) for sources with
observed luminosity erg . In the
Cosmological evolution survey (COSMOS), we find an observed CT fraction of
(40/272) or when corrected for
the survey sensitivity. When comparing to low redshift AGN with similar X-ray
luminosities, our results imply the CT AGN fraction is consistent with having
no redshift evolution. Finally, we provide SC equations that can be used to
find high-redshift CT AGN (z>1) for current (XMM-Newton) and future (eROSITA
and ATHENA) X-ray missions.Comment: 10 pages, 8 figure
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