178 research outputs found
The populations of planetary nebulae in the direction of the Galactic bulge
We have observed 44 planetary nebulae (PNe) in the direction of the Galactic
bulge, and merged our data with published ones. We have distinguished, in the
merged sample of 164 PNe, those PNe most likely to prtain physically to the
Galactic bulge and those most likely to belong to the Galactic disk. We have
determined the chemical composition of all the 164 objects in a coherent way.
We looked for stellar emission features and discovered 14 new [WR] stars and 15
new weak emission line central stars.
The analyzed data led us to the following conclusions: (1) The spectral type
distribution of [WR] stars is very different in the bulge and in the disk of
the Galaxy. However, the observed distributions are strongly dependent on
selection effects. (2) The proportion of [WR] PNe is significantly larger in
the bulge than in the disk. (3) The oxygen abundances in [WR] stars do no
appear to be significantly affected by nucleosynthesis and mixing in the
progenitors. (4) The O/H gradient of the Galactic disk PNe population flattens
in the most internal parts of the Galaxy. (5) The median oxygen abundance in
the bulge PN population is larger by 0.2 dex than in the disk population seen
in the direction of the bulge. (6) Bulge PNe with smaller O/H tend to have
smaller radial velocities. (7) The oxygen abundance distribution of bulge PNe
is similar in shape to that of the metallicity distribution of bulge giants,
but significantly narrower. (8) The location of SB 32 (PN G 349.7-09.1) in the
(V_lsr, l_II) diagram and its low oxygen abundance argues that it probably
belongs to the halo population.Comment: 14 pages, 16 figures. Accepted for publication in A&
New groups of planetary nebulae with peculiar dust chemistry towards the Galactic bulge
We investigate Galactic bulge planetary nebulae without emission-line central
stars for which peculiar infrared spectra have been obtained with the Spitzer
Space Telescope, including the simultaneous signs of oxygen and carbon based
dust. Three separate sub-groups can be defined characterized by the different
chemical composition of the dust and the presence of crystalline and amorphous
silicates.
We find that the classification based on the dust properties is reflected in
the more general properties of these planetary nebulae. However, some observed
properties are difficult to relate to the common view of planetary nebulae. In
particular, it is challenging to interpret the peculiar gas chemical
composition of many analyzed objects in the standard picture of the evolution
of planetary nebulae progenitors.
We confirm that the dual-dust chemistry phenomenon is not limited to
planetary nebulae with emission-line central stars.Comment: 17 pages, 13 figure
The VMC survey - XI : Radial Stellar Population Gradients in the Galactic Globular Cluster 47 Tucanae
Copyright American Astronomical SocietyWe present a deep near-infrared color-magnitude diagram of the Galactic globular cluster 47 Tucanae, obtained with the Visible and Infrared Survey Telescope for Astronomy (VISTA) as part of the VISTA near-infrared Y, J, Ks survey of the Magellanic System (VMC). The cluster stars comprising both the subgiant and red giant branches exhibit apparent, continuous variations in color-magnitude space as a function of radius. Subgiant branch stars at larger radii are systematically brighter than their counterparts closer to the cluster core; similarly, red-giant-branch stars in the cluster's periphery are bluer than their more centrally located cousins. The observations can very well be described by adopting an age spread of ~0.5 Gyr as well as radial gradients in both the cluster's helium abundance (Y) and metallicity (Z), which change gradually from (Y = 0.28, Z = 0.005) in the cluster core to (Y = 0.25, Z = 0.003) in its periphery. We conclude that the cluster's inner regions host a significant fraction of second-generation stars, which decreases with increasing radius; the stellar population in the 47 Tuc periphery is well approximated by a simple stellar population.Peer reviewe
Quantitative value of aldosterone-renin ratio for detection of aldosterone-producing adenoma: The Aldosterone-Renin Ratio for Primary Aldosteronism (AQUARR) study
Background Current guidelines recommend use of the aldosterone\u2010renin ratio (ARR) for the case detection of primary aldosteronism followed by confirmatory tests to exclude false\u2010positive results from further diagnostic workup. We investigated the hypothesis that this could be unnecessary in patients with a high ARR value if the quantitative information carried by the ARR is taken into due consideration.
Methods and Results We interrogated 2 large data sets of prospectively collected patients studied with the same predefined protocol, which included the captopril challenge test. We used an unambiguous diagnosis of aldosterone\u2010producing adenoma as reference index. We also assessed whether the post\u2010captopril ARR and plasma aldosterone concentration fall furnished a diagnostic gain over baseline ARR values. We found that the false\u2010positive rate fell exponentially, and, conversely, the specificity increased with rising ARR values. At receiver operating characteristics curves and diagnostic odds ratio analysis, the high baseline ARR values implied very high positive likelihood ratio and diagnostic odds ratio values. The baseline and post\u2010captopril ARR showed similar diagnostic accuracy (area under the receiver operating characteristics curve) in both the exploratory and validation cohorts, indicating lack of diagnostic gain with this confirmatory test (between\u2010area under the curve difference, 0.005; 95% CI, 120.031 to 0.040; P=0.7 for comparison, and 0.05; 95% CI, 120.061 to 0.064; P=0.051 for comparison, respectively).
Conclusions These results indicate that the ARR conveys key quantitative information that, if properly used, can simplify the diagnostic workup, resulting in saving of money and resources. This can offer the chance of diagnosis and ensuing adrenalectomy to a larger number of hypertensive patients, ultimately resulting in better control of blood pressure
SO045A NATIONWIDE SURVEY ON RADIATION RISK OF CANCER FROM MEDICAL IMAGING IN END STAGE KIDNEY DISEASE AND IN TRANSPLANT PATIENTS
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Clinico‐histopathological review of 255 patients who underwent parotidectomy for pleomorphic adenoma: a 10‐year retrospective study—a proposal for an optimal diagnostic and therapeutic algorithm for patients with recurrent pleomorphic adenoma
Purpose Pleomorphic adenoma (mixed tumor) is the most common neoplasm of the parotid gland and one of the most frequent types of salivary gland tumor, generally with benign behavior and relatively slow growing. The adenomas could arise from the superficial, deep or from both superficial and deep parotid’s lobes.
Methods The aim of this review is to retrospectively analyze the surgical management of patients with pleomorphic adenoma of the parotid gland performed at the Department of Otorhinolaryngology (Department of Sense Organs of “Azienda Policlinico Umberto I” in Rome), from 2010 to 2020, with a focus on the percentage of recurrence and on the complication related to surgery to suggest an optimal diagnostic and therapeutic algorithm for patients with recurrent pleomorphic adenoma. The analysis of the complications observed in case of different surgical approaches was performed using the X2 test.
Results The choice of a surgical approach (superficial parotidectomy—SP, total parotidectomy—TP, extracapsular dissec- tion—ECD) depends on several elements, such as the location and the size of the adenoma, the availability of existing technical facilities and the professional experience of the surgeon. A transient facial palsy was present in 37.6%, 2.7% reported a permanent facial nerve palsy, 1.6% developed a salivary fistula, 1.6% a post-operative bleeding and 2.3% showed Frey Syndrome.
Conclusion The surgical management of this benign lesion is required, even in asymptomatic cases, to prevent the progressive growing and to reduce the risk of malignant transformation. The goal of surgical excision is to obtain the complete resection to minimize the risk of tumor recurrence and avoiding facial nerve disability. Therefore, an accurate preoperative study of the lesion and the choice of the most appropriate surgical treatment are essential to minimize the rate of recurrence
Diagnostic predictors of immunotherapy response in head and neck squamous cell carcinoma
Programmed cell death ligand-1 (PD-L1) binds PD-1 on CD8+ lymphocytes, inhibiting their cytotoxic action. Its aberrant expression by head and neck squamous cell carcinoma (HNSCC) cells leads to immune escape. Pembrolizumab and nivolumab, two humanized monoclonal antibodies against PD-1, have been approved in HNSCC treatment, but similar to 60% of patients with recurrent or metastatic HNSCC fail to respond to immunotherapy and only 20 to 30% of treated patients have long-term benefits. The purpose of this review is to analyze all the fragmentary evidence present in the literature to identify what future diagnostic markers could be useful for predicting, together with PD-L1 CPS, the response to immunotherapy and its durability. We searched PubMed, Embase, and the Cochrane Register of Controlled Trials and we summarize the evidence collected in this review. We confirmed that PD-L1 CPS is a predictor of response to immunotherapy, but it should be measured across multiple biopsies and repeatedly over time. PD-L2, IFN-gamma, EGFR, VEGF, TGF-beta, TMB, blood TMB, CD73, TILs, alternative splicing, tumor microenvironment, and some macroscopic and radiological features are promising predictors worthy of further studies. Studies comparing predictors appear to give greater potency to TMB and CXCR9
Stellar Processes Near the Massive Black Hole in the Galactic Center
A massive black hole resides in the center of most, perhaps all galaxies. The
one in the center of our home galaxy, the Milky Way, provides a uniquely
accessible laboratory for studying in detail the connections and interactions
between a massive black hole and the stellar system in which it grows; for
investigating the effects of extreme density, velocity and tidal fields on
stars; and for using stars to probe the central dark mass and probe
post-Newtonian gravity in the weak- and strong-field limits. Recent results,
open questions and future prospects are reviewed in the wider context of the
theoretical framework and physical processes that underlie them.
Contents: [1] Introduction (1.1) Astrophysical context (1.2) Science
questions (1.3) Scope and connections to related topics [2] Observational
overview: Stars in the Galactic center (2.1) The central 100 parsecs (2.2) The
central parsec [3] Stellar dynamics at extreme densities (3.1) Physical
processes and scales (3.2) The stellar cusp in the Galactic center (3.3) Mass
segregation (3.4) Stellar Collisions [4] Probing the dark mass with stellar
dynamics (4.1) Weighing and pinpointing the dark mass (4.2) Constraints on
non-BH dark mass alternatives (4.3) Limits on MBH binarity (4.4) High-velocity
runaway stars [5] Probing post-Newtonian gravity near the MBH (5.1)
Relativistic orbital effects (5.2) Gravitational lensing [6] Strong star-MBH
interactions (6.1) Tidal disruption (6.2) Dissipative interactions with the MBH
[7] The riddle of the young stars (7.1) The difficulties of forming or
importing stars near a MBH (7.2) Proposed solutions (7.3) Feeding the MBH with
stellar winds [8] Outlook (8.1) Progress report (8.2) Future directionsComment: Invited review article, to appear in Physics Reports. 101 p
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