1,495 research outputs found
Spatially-resolved spectroscopy of narrow-line Seyfert 1 host galaxies
We present optical integral field spectroscopy for five narrow-line
Seyfert 1 galaxies (NLS1s) host galaxies, probing their host galaxies at
kpc scales. Emission lines in the nuclear AGN spectra and the
large-scale host galaxy are analyzed separately, based on an AGN-host
decomposition technique. The host galaxy gas kinematics indicates large-scale
gas rotation in all five sources. At the probed scales of kpc,
the host galaxy gas is found to be predominantly ionized by star formation
without any evidence of a strong AGN contribution. None of the five objects
shows specific star formation rates exceeding the main sequence of low-redshift
star forming galaxies. The specific star formation rates for MCG-05-01-013 and
WPVS 007 are roughly consistent with the main sequence, while ESO 399-IG20, MS
22549-3712, and TON S180 show lower specific star formation rates, intermediate
to the main sequence and red quiescent galaxies. The host galaxy metallicities,
derived for the two sources with sufficient data quality (ESO 399-IG20 and
MCG-05-01-013), indicate central oxygen abundances just below the low-redshift
mass-metallicity relation. Based on this initial case study, we outline a
comparison of AGN and host galaxy parameters as a starting point for future
extended NLS1 studies with similar methods.Comment: 25 pages, 8 figures, accepted for publication in ApJ on 3 September
201
Thermal, mechanical and rheological behaviors of nanocomposites based on UHMWPE/paraffin oil/carbon nanofiller obtained by using different dispersion techniques.
Ultra-high molecular weight polyethylene (UHMWPE) is a very attractive polymer employed as a high performance material. For its high viscosity, dispersion of fillers is considered a critical point in UHMWPE nanocomposites preparation process. Currently, paraffin oil (PO) is used extensively to overcome this issue in an assisted melt-mixing process. In this work, we have prepared nanocomposites based on UHMWPE, carbon nanofiller (CNF) and PO mixed by different mixing methods: magnetic stirring, ball milling (BM), ultrasonic and Mini-Lab extruder (EX). The aim of this work was to check the effect of the dispersion method on the mechanical and thermal features of UHMWPE/CNF nano composites in order to obtain a material with improved mechanical and physical properties. The samples were characterized by calorimetric, density, mechanical tensile and rheological analyses. Experimental results highlighted that the nanocomposites produced by EX and BM exhibits the best dispersion, good filler matrix interaction and had significantly improved mechanical properties compared to pure UHMWPE. For instance, for the BM method, the yield strength improved to 18.6 MPa (+96%), the yield strain improved by 60%, while stress at break improved by 13%. In summary, the EX improved the stiffness while the BM produced better ductility, melting temperature and the crystalline degree of the nanocomposites
Tethering of Gly-Arg-Gly-Asp-Ser-Pro-Lys Peptides on Mg-Doped Hydroxyapatite
Stem cell homing, namely the recruitment of mesenchymal stem cells (MSCs) to injured tissues, is highly effective for bone regeneration in vivo. In order to explore whether the incorporation of mimetic peptide sequences on magnesium-doped (Mg-doped) hydroxyapatite (HA) may regulate the homing of MSCs, and thus induce cell migration to a specific site, we covalently functionalized MgHA disks with two chemotactic/haptotactic factors: either the fibronectin fragment III1-C human (FF III1-C), or the peptide sequence Gly-Arg-Gly-Asp-Ser-Pro-Lys, a fibronectin analog that is able to bind to integrin transmembrane receptors. Preliminary biological evaluation of MSC viability, analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test, suggested that stem cells migrate to the MgHA disks in response to the grafted haptotaxis stimuli
Gender specific medicine in liver diseases: a point of view.
Gender medicine focuses on the patho-physiological, clinical, prevention and treatment differences in diseases that are equally represented in men and women. The purpose of gender medicine is to ensure that each individual man and woman receives the best treatment possible based on scientific evidence. The concept of “gender” includes not only the sexual characteristics of individuals but also physiological and psychological attributes of men and women, including risk factors, protective/aggravating effects of sexual hormones and variances linked to genetics and corporal structures that explain biological and physiological differences between men and women. It is very important to consider all the biological, physiological, functional, psychological, social and cultural characteristics to provide patients with individualized disease management. Herein, we critically analyze the literature regarding gender differences for diseases and acquired conditions of the most representative hepatic pathologies: primary biliary cirrhosis, autoimmune hepatitis, primary sclerosing cholangitis, non alcoholic fatty liver disease and alcoholic liver disease, and viral chronic hepatitis B and C. The last section addresses hemochromatosis, which is a prevalent iron overload disorder in the Caucasian population. This review aims to describe data from the literature concerning viral chronic hepatitis during pregnancy, management during pregnancy and delivery, and new effective drugs for the prevention of maternal infection transmission without significant adverse effects or complications
Preventing Tax arbitrage via Hybrid Mismatches: BEPS Action 2 and Developing Countries
The Organization for Economic Cooperation and Development (OECD) under Base Erosion and
Profit Shifting (BEPS) Action 2 indicated that tax arbitrage via hybrid mismatch arrangements "result in a
substantial erosion of the taxable bases of the countries concerned" and "have an overall negative impact on
competition, efficiency, transparency and fairness." The relevant action allowing for neutralising the effects of
hybrid mismatch arrangements is therefore needed and justified. To achieve that purpose, the OECD
developed different anti-hybrid rules under BEPS Action 2. In that regard, however, one may ask whether
addressing tax arbitrage via hybrid mismatches as proposed by the OECD is of interest and relevance for
developing countries. This paper aims to map that unexplored research area by means of a comparative
analysis in four developing countries - Uruguay, Colombia, Brazil, and South Africa.Series: WU International Taxation Research Paper Serie
Effect of Ethyl Ester L-Lysine Triisocyanate addition to produce reactive PLA/PCL bio-polyester blends for biomedical applications
We report in this paper the effects of Ethyl Ester L-Lysine Triisocyanate (LTI) on the physical-mechanical properties of Poly(lactide)/Poly(ε-caprolactone) (PLA/PCL) polyesters blends. The PLA/PCL ratios considered were 20/80, 50/50 and 80/20 (wt/wt %) and LTI was added in amounts of 0.0-0.5-1.0 phr. PLA and PCL reacted with LTI during processing in a Brabender twin screw internal mixer to produce block copolymers in-situ. The resulting blends have been characterized by torque measurements, uniaxial tensile tests, Differential Scanning Calorimeter, contact angle measurements with a Phosphate Buffered Saline (PBS) solution, ATR analysis and morphological SEM observations. Experimental results highlighted how LTI enhanced interaction and dispersion of the two components, resulting into a synergic effect in mechanical properties. Mechanical and physical properties can be tailored by changing the blend composition. The most noticeable trend was an increase in ductility of the mixed polymers. Besides, LTI decreased blend’s wet ability in PBS and lowered the starting of crystalline phase formation for both polymers, confirming an interaction among them. These reactive blends could find use as biomedical materials, e.g. absorbable suture threads or scaffolds for cellular growth
Design of a Novel Long-Reach Cable-Driven Hyper-Redundant Snake-like Manipulator for Inspection and Maintenance
Robotic inspection and maintenance are gaining importance due to the number of different scenarios in which robots can operate. The use of robotic systems to accomplish such tasks has deep implications in terms of safety for human workers and can significantly extend the life of infrastructures and industrial facilities. In this context, long-reach cable-driven hyper-redundant robots can be employed to inspect areas that are difficult to reach and hazardous environments such as tanks and vessels. This paper presents a novel long-reach cable-driven hyper-redundant robot called SLIM (Snake-Like manipulator for Inspection and Maintenance). SLIM consists of a robotic arm, a pan and tilt mechanism as end-effector, and an actuation box that can rotate and around which the arm can wrap. The robot has a total of 15 degrees of freedom and, therefore, for the task of positioning the tool centre point in a bi-dimensional Cartesian space with a specific attitude, it has 10 degrees of redundancy. The robot is designed to operate in harsh environments and high temperatures and can deploy itself up to about 4.8 m. This paper presents the requirements that drove the design of the robot, the main aspects of the mechanical and electronic systems, the control strategy, and the results of preliminary experimental tests performed with a physical prototype to evaluate the robot performances
Presence of wolbachia in three hymenopteran species : diprion pini (Hymenoptera: Diprionidae), neodiprion sertifer (Hymenoptera: Diprionidae), and dahlbominus fuscipennis (Hymenoptera: Eulophidae)
Sawflies are important pests of various plant species. Diprion pini (L.) and Neodiprion sertifer (Geoffroy) (Hymenoptera: Diprionidae) are two of the most important sawfly pests in Italy, and both species are parasitized by the hymenopteran parasitoid Dahlbominus fuscipennis (Zetterstedt). Bacterial endosymbionts are currently studied for their high potential in strategies of biocontrol in a number of insect species. In this study, we investigated the presence of symbiotic bacteria (Wolbachia and Cardinium) in the three species of hymenoptera mentioned earlier, both in wild and laboratory populations. Although all samples were negative for the presence of Cardinium, 100% prevalence for Wolbachia was detected, as all examined individuals resulted to be PCR positive. Furthermore, 16S rDNA and ftsZ gene sequencing indicated that all individuals from the three hymenopteran species are infected by a single Wolbachia strain. Additionally, we report the presence of gynandromorphic individuals in D. pini, both in wild and laboratory-reared populations. Heat treatments on D. pini colonies removed the Wolbachia symbionts, but they also prevented the development of adults
Engineering of chitosan-hydroxyapatite-magnetite hierarchical scaffolds for guided bone growth
Bioabsorbable materials have received increasing attention as innovative systems for the development of osteoconductive biomaterials for bone tissue engineering. In this paper, chitosan-based composites were synthesized adding hydroxyapatite and/or magnetite in a chitosan matrix by in situ precipitation technique. Composites were characterized by optical and electron microscopy, thermogravimetric analyses (TGA), x-ray diffraction (XRD), and in vitro cell culture studies. Hydroxyapatite and magnetite were found to be homogeneously dispersed in the chitosan matrix and the composites showed superior biocompatibility and the ability to support cell attachment and proliferation; in particular, the chitosan/hydroxyapatite/magnetite composite (CS/HA/MGN) demonstrated superior bioactivity with respect to pure chitosan (CS) and to the chitosan/hydroxyapatite (CS/HA) scaffolds
Observation of resonances consistent with pentaquark states in decays
Observations of exotic structures in the channel, that we refer to
as pentaquark-charmonium states, in decays are
presented. The data sample corresponds to an integrated luminosity of 3/fb
acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude
analysis is performed on the three-body final-state that reproduces the
two-body mass and angular distributions. To obtain a satisfactory fit of the
structures seen in the mass spectrum, it is necessary to include two
Breit-Wigner amplitudes that each describe a resonant state. The significance
of each of these resonances is more than 9 standard deviations. One has a mass
of MeV and a width of MeV, while the second
is narrower, with a mass of MeV and a width of MeV. The preferred assignments are of opposite parity, with one
state having spin 3/2 and the other 5/2.Comment: 48 pages, 18 figures including the supplementary material, v2 after
referee's comments, now 19 figure
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