3,291 research outputs found

    Abundance trend with condensation temperature for stars with different Galactic birth places

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    During the past decade, several studies reported a correlation between chemical abundances of stars and condensation temperature (also known as Tc trend). However, the real astrophysical nature of this correlation is still debated. The main goal of this work is to explore the possible dependence of the Tc trend on stellar Galactocentric distances, Rmean. We used high-quality spectra of about 40 stars observed with the HARPS and UVES spectrographs to derive precise stellar parameters, chemical abundances, and stellar ages. A differential line-by-line analysis was applied to achieve the highest possible precision in the chemical abundances. We confirm previous results that [X/Fe] abundance ratios depend on stellar age and that for a given age, some elements also show a dependence on Rmean. When using the whole sample of stars, we observe a weak hint that the Tc trend depends on Rmean. The observed dependence is very complex and disappears when only stars with similar ages are considered. To conclude on the possible dependence of the Tc trend on the formation place of stars, a larger sample of stars with very similar atmospheric parameters and stellar ages observed at different Galactocentric distances is neededComment: Accepted by A&

    APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy

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    The Apache Point Observatory Galactic Evolution Experiment (APOGEE) provides the opportunity to measure elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze the chemical abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances and the first time C, N, P, K, V, Cr, Co, and Ni have been studied at high-resolution in this galaxy. We find that the Sgr stars with [Fe/H] \gtrsim -0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light IMF, one lacking the most massive stars that would normally pollute the ISM with the hydrostatic elements. We use a simple chemical evolution model, flexCE to further backup our claim and conclude that recent stellar generations of Fornax and the LMC could also have formed according to a top-light IMF.Comment: 14 pages, 12 figures, accepted for publication in Ap

    Signaling via interleukin-4, receptor alpha chain is required for successful vaccination against schistosomiasis in BALB/c mice

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    Radiation-attenuated (RA) schistosome larvae are potent stimulators of innate immune responses at the skin site of exposure (pinna) that are likely to be important factors in the development of Th1-mediated protective immunity. In addition to causing an influx of neutrophils, macrophages, and dendritic cells (DCs) into the dermis, RA larvae induced a cascade of chemokine and cytokine secretion following in vitro culture of pinna biopsy samples. While macrophage inflammatory protein 1 and interleukin-1 (IL-1) were produced transiently within the first few days, the Th1-promoting cytokines IL-12 and IL-18 were secreted at high levels until at least day 14. Assay of C3H/HeJ mice confirmed that IL-12 secretion was not due to lipopolysaccharide contaminants binding Toll-like receptor 4. Significantly, IL-12 p40 secretion was sustained in pinnae from vaccinated mice but not in those from nonprotected infected mice. In contrast, IL-10 was produced from both vaccinated and infected mice. This cytokine regulates IL-12-associated dermal inflammation, since in vaccinated IL-10/ mice, pinna thickness was greatly increased concurrent with elevated levels of IL-12 p40. A significant number of IL-12 p40 cells were detected as emigrants from in vitro-cultured pinnae, and most were within a population of rare large granular cells that were Ia, consistent with their being antigen-presenting cells. Labeling of IL-12 cells for CD11c, CD205, CD8, CD11b, and F4/80 indicated that the majority were myeloid DCs, although a proportion were CD11c F4/80, suggesting that macrophages were an additional source of IL-12 in the skin

    Is Subdural Peritoneal Shunt Placement an Effective Tool for the Management of Recurrent/Chronic Subdural Hematoma?

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    Objectiveæ To describe a surgical techniqueæand to report using a retrospective studyæthe efficacy of peritoneal shunts for the treatment of recurrent/chronic subdural hematoma (CSDH). We describeæthe considerations, complications, and outcomes related to this technique. Methodsæ In a retrospectiveæcohort study, 125 charts with a diagnosis of subacute/chronic subdural hematoma were assigned for evaluation. Of the charts reviewed, 18 charts were found from subjects with a diagnosis of recurrent sub-acute or chronic subdural hematoma. All patients had undergone initial surgical treatment of their condition followed by peritoneal shunt placement to help alleviate intracranial pressure. Factors including the age, size of subdural hematoma, number of previous events, BMI, complications, survival, and clinical course were analyzed. Resultsæ After subdural peritoneal shunt placement all patients had full neurological recovery with no complaints of headaches, lethargy, weakness, confusion or seizures. None of the cases had new subdural hematoma episodes after placement for a minimum of a two-year period (mean 26.1 months) (range 24.3-48.6 months). No postoperative complications were reported. The rates of postoperative hemorrhage, infection, distal catheter revision, and perioperative seizures was found to be zero percent. Shunt drainage was successful in all cases, draining 85% of the blood in the first 48 hours. There was no significant relationship between complications and the use of anticoagulants four weeks after surgery. Conclusions Peritoneal shunts, though rarely used, are a viable option in the treatment of sub-acute/chronic subdural hematomas. When pursuing this treatment, this technique is recommended to mitigate the risks of repeat surgical intervention and lessen perioperative time in high-risk patients

    The Chemistry of Griseofulvin

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    Search for narrow resonances in dilepton mass spectra in proton-proton collisions at sqrt(s) = 13 TeV and combination with 8 TeV data

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    A search for narrow resonances in dielectron and dimuon invariant mass spectra has been performed using data obtained from proton–proton collisions at View the MathML sources=13 TeV collected with the CMS detector. The integrated luminosity for the dielectron sample is 2.7 fb−1 and for the dimuon sample 2.9 fb−1. The sensitivity of the search is increased by combining these data with a previously analyzed set of data obtained at View the MathML sources=8 TeV and corresponding to a luminosity of 20 fb−1. No evidence for non-standard-model physics is found, either in the 13 TeV data set alone, or in the combined data set. Upper limits on the product of production cross section and branching fraction have also been calculated in a model-independent manner to enable interpretation in models predicting a narrow dielectron or dimuon resonance structure. Limits are set on the masses of hypothetical particles that could appear in new-physics scenarios. For the View the MathML sourceZSSM′ particle, which arises in the sequential standard model, and for the superstring inspired View the MathML sourceZψ′ particle, 95% confidence level lower mass limits for the combined data sets and combined channels are found to be 3.37 and 2.82 TeV, respectively. The corresponding limits for the lightest Kaluza–Klein graviton arising in the Randall–Sundrum model of extra dimensions with coupling parameters 0.01 and 0.10 are 1.46 and 3.11 TeV, respectively. These results significantly exceed the limits based on the 8 TeV LHC data

    Search for light bosons in decays of the 125 GeV Higgs boson in proton-proton collisions at root s=8 TeV

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    The Importance Of Monoclonal Proteins Determination For The Correct Diagnosis Of Transthyretin Cardiac Amyloidosis By [Tc-99m]Tc-diphosphonates

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    EPS-066 Aim/Introduction: To analyze the influence of the determination of free monoclonal proteins in blood and urine in the final diagnosis of Transthyretin Cardiac Amyloidosis (TTRA). Materials and Methods: We have analyzed 200 [99mTc]Tc-diphosphonates scans: 192 performed on 190 patients under suspicion of TTRA and 7 patients with grade II-III radiotracer myocardial deposit as a casual finding (November/2013 - January/2020). Likewise, clinical and laboratory characteristics (heart failure, LVEF, proBNP levels, immunofixation in serum and/or urine for the detection of monoclonal chains and chronic renal failure) have been evaluated. A positive case has been considered for TTRAwt or senile (Score Perugini II-III scan, negative immunofixation in serum and/or urine, negative genetic study), positive case for hereditary TTRA (Score Perugini II-III scan, negative immunofixation and positive genetic study), positive case for secondary amyloidosis (positive immunofixation and presence of hematologic malignancy) and undetermined amyloidosis (immunofixation not performed or positive and absence of haematologic malignancies at follow-up). Results: 59 positive scans have been detected, 47 men (79’7%) and 12 women (20’3%). The mean age of the group of positives was 82’66 years, while that of the negatives was 72’15. The mean proBNP levels in the positives are 7561, compared to 5869 in the negative group. Immunofixation (serum and/or urine for detection of kappa or lambda monoclonal chains at 30 (50.8%) has been performed on these patients. Finally, 37.2% (22/59) resulted in ATTRwt, 3.4% (2/59) hereditary ATTR (genetic study: variant E54Q and mutation c.424> A (p.Va.122Ile) in exon 4 of TTR) and 1.7% (1/59) secondary amyloidosis. The remaining 34/59 (57.7%) cases were undetermined amyloidosis (6 positive immunofixation and 27 without monoclonal proteins determination). Conclusion: Determination of monoclonal bands in blood and urine is mandatory to correctly characterize cases of cardiac amyloidosis and, in presence of monoclonal bands, to assess the existence of underlying haematological malignancies

    Search for Evidence of the Type-III Seesaw Mechanism in Multilepton Final States in Proton-Proton Collisions at root s=13 TeV

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