102 research outputs found

    AGN Environments in the Sloan Digital Sky Survey I: Dependence on Type, Redshift, and Luminosity

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    We explore how the local environment is related to the redshift, type, and luminosity of active galactic nuclei (AGN). Recent simulations and observations are converging on the view that the extreme luminosity of quasars is fueled in major mergers of gas-rich galaxies. In such a picture, quasars are expected to be located in regions with a higher density of galaxies on small scales where mergers are more likely to take place. However, in this picture, the activity observed in low-luminosity AGN is due to secular processes that are less dependent on the local galaxy density. To test this hypothesis, we compare the local photometric galaxy density on kiloparsec scales around spectroscopic Type I and Type II quasars to the local density around lower luminosity spectroscopic Type I and Type II AGN. To minimize projection effects and evolution in the photometric galaxy sample we use to characterize AGN environments, we place our random control sample at the same redshift as our AGN and impose a narrow redshift window around both the AGN and control targets. We find that higher luminosity AGN have more overdense environments compared to lower luminosity AGN on all scales out to our 2\Mpchseventy limit. Additionally, in the range 0.3⊽z⊽0.60.3\leqslant z\leqslant 0.6, Type II quasars have similarly overdense environments to those of bright Type I quasars on all scales out to our 2\Mpchseventy limit, while the environment of dimmer Type I quasars appears to be less overdense than the environment of Type II quasars. We see increased overdensity for Type II AGN compared to Type I AGN on scales out to our limit of 2\Mpchseventy in overlapping redshift ranges. We also detect marginal evidence for evolution in the number of galaxies within 2\Mpchseventy of a quasar with redshift.Comment: 30 pages, 9 figures. Major revisions made for current version. Some content in previous version has been removed to refocus content on redshift and type effects. This content will be deferred to later work

    Comparative life cycle assessment of Fe2O3-based fibers as anode materials for sodium-ion batteries

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    AbstractSodium-ion batteries (SIBs) potentially represent a more sustainable, less expensive and environmentally friendly alternative to lithium-ion batteries. The development of new low-cost, non-toxic, highly performing electrode materials is the key point for the SIB technology advances. This study develops a basic life cycle assessment (LCA) model for the evaluation of the production by electrospinning of iron (III) oxide-based fibers to be used as anode materials in SIBs. Indeed, it has been recently demonstrated that electrospun silicon-doped iron (III) oxide (Fe2O3) fibers exhibit outstanding electrochemical properties and gravimetric capacities never achieved before for pure Fe2O3-based anodes. The LCA methodology is utilized in order to analyze the environmental burdens (from raw material extraction to manufacturing process) of these electrode materials. The simplified comparative LCA studies, conducted to assess the environmental impacts associated with the electrospun Fe2O3 and Fe2O3:Si fibers at the same cell performance, demonstrate that the Si-doped anode material, which exhibits better electrochemical performance with respect to the undoped one, has also lower impact for each category of damage, namely human health, ecosystem quality and resources

    β-arrestin1-mediated acetylation of Gli1 regulates Hedgehog/Gli signaling and modulates self-renewal of SHH medulloblastoma cancer stem cells

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    Background Aberrant Sonic Hedgehog/Gli (Hh/Gli) signaling pathway is a critical regulator of Sonic hedgehog medulloblastoma (SHH-MB). Cancer stem cells (CSCs), thought to be largely responsible for tumor initiation, maintenance, dissemination and relapse, have been identified in SHH-MB. Since we previously demonstrated that Hh/Gli signaling controls CSCs features in SHH-MB and that in these tumors miR-326 is down regulated, here we investigated whether there is a functional link between Hh/Gli signaling and miR-326. Methods We evaluated β-arrestin1 (Arrb1) and its intragenic miR-326 levels in CSCs derived from SHH-MB. Subsequently, we modulated the expression of Arrb1 and miR-326 in CSCs in order to gain insight into their biological role. We also analyzed the mechanism by which Arrb1 and miR-326 control Hh/Gli signaling and self-renewal, using luciferase and protein immunoprecipitation assays. Results Low levels of Arrb1 and miR-326 represent a feature of CSCs derived from SHH-MB. We observed that re-expression of Arrb1 and miR-326 inhibits Hh/Gli signaling pathway at multiple levels, which cause impaired proliferation and self-renewal, accompanied by down regulation of Nanog levels. In detail, miR-326 negatively regulates two components of the Hh/Gli pathway the receptor Smoothened (Smo) and the transcription factor Gli2, whereas Arrb1 suppresses the transcriptional activity of Gli1, by potentiating its p300-mediated acetylation. Conclusions Our results identify a new molecular mechanism involving miR-326 and Arrb1 as regulators of SHH-MB CSCs. Specifically, low levels of Arrb1 and miR-326 trigger and maintain Hh/Gli signaling and self-renewal

    Human Cardiopoietic Amniotic Fluid cell population: characterization and terminal differentiation

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    Rationale. Human amniotic fluid-derived (hAF) stem cells are considered a novel class of multipotent stem cells, sharing characteristics of both embryonic and adult stem cells. In fact, they proliferate rapidly, are able to differentiate into cells of all the embryonic germ layers, but do not form teratoma. It has been already reported that the embryoid bodies (EBs) obtained from hAFs have a cardiac potential, but it has not been described a functional terminal differentiation in cardiomyocytes (CMs) yet. Objective. Aim of this study was to foster the cardiomyogenic potential of hAFs in order to obtain a cellular population with morphological and functional features of CMs. Methods and Results. AFCs were exposed sequentially to inducing factors (Ascorbic Acid, 5-Azacytidine, BMP4, ActivinA, VEGF) up to 15 days and differentiation was monitored. Only the hAF samples expressing the multipotency markers SSEA4, OCT4 and CD90 (CardiopoieticAF) responded to the differentiation process loosing their stemness and increasing the cardiac nuclear factors NKX2.5 and GATA4. After the differentiation cells expressed high levels of the sarcomeric proteins (cTnT, ÎąMHC and ÎąSA), the gap junction marker Connexin43 and both atrial and ventricular markers; moreover, up to 90% of the cells was positive for CACNA1C and SERCA2a, cardiac calcium pumps involved in the excitation/contraction coupling, and about 30% of the CardiopoieticAF-derived cells presented spontaneous intracellular Ca2+ waves and Ca2+ fluctuation in response to caffeine or adrenergic stimulation. Some spontaneous beating foci were also observed. Conclusion. Our results demonstrate that CardiopoietichAFs can fully differentiate into a homogenous population of CM-like cells, characterized by cardiac-specific molecular, structural, and functional properties. Thus, CardiopoietichAFs can hold great promise for the development of in vitro models of cardiac genetic disorders, for drug discovery and testing, and for the emerging field of cardiovascular regenerative medicine

    Study of cardiomyogenic potential of human Amniotic Fluid Stem Cells

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    It has been shown that Amniotic fluid stem cells (AFSCs) have characteristics intermediate between pluripotent embryonic and lineage-restricted adult stem cells, and are non-tumorigenic and low immunogenic. Moreover, they are obtained without destroying human embryos, so that preventing most of the ethical and social controversy. Human AFSCs express some genes specific of both embryonic (OCT3/4, NANOG, c-MYC) and primordial germ stem cells (Fragilis, Stella, c-KIT). We have demonstrated that hAFSCs form in vitro embryoid bodies (EBs) and express markers of three germ layers. Studies reported the ability of hAFSCs to differentiate in vitro into adipocytes and osteocytes, but only few data are available on their cardiomyogenic potential. Aim of this study is to analyze hAFSCs differentiation through the cardiac pathway. Embryonic Bodies (EBs) were obtained from hAFSCs cultured in presence of ascorbic acid and 5-aza-2’-deoxycytidine. Cardiomyogenic potential of hAFSCs and EBs was explored by WB and immunoflorescent analyses of specific markers. Simultaneous quantitative detection and cellular localization analysis of cardiomyogenic markers were conducted with an ImageStream multispectral imaging flow cytometer (Amnis-Seattle, WA) equipped with IDEAS statistical software. We evidenced that both AFSCs and EBs at early stage express Nkx2.5, a transcription factor expressed by cardiomyocytes precursor cells. Moreover, ImageStream imaging cytometer analysis evidenced that EBs formation was accompanied by an up-regulation of Nkx2.5 expression (36.54±1.83% and 64.68±3.23% positive cells in hAFSC and EBs respectively, p<.005) and by a significant nuclear translocation (12.98±0.64% and 37.98±1.9% nuclear positive cells in hAFSC and EBs respectively, p<.005). Microscopical analysis evidenced inside the EBs cells positive for the presence of cardiac α-Myosin heavy chain protein structurally organized in oriented filaments. Moreover, we detected cells expressing Connexin43. These results evidenced that EBs obtained from hAFSCs cultured in permissive conditions terminally differentiate into cardiomyocytes and suggest them as possible model to study the cardiac differentiation

    Treatment Decision-Making of Secondary Prevention After Venous Thromboembolism: Data From the Real-Life START2-POST-VTE Register

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    Patients with venous thromboembolism (VTE) should receive a decision on the duration of anticoagulant treatment (AT) that is often not easy to make. Sixteen Italian clinical centers included patients with recent VTE in the START2-POST-VTE register and reported the decisions taken on duration of AT in each patient and the reasons for them. At the moment of this report, 472 (66.9%) of the 705 patients included in the registry were told to stop AT in 59.3% and to extend it in 40.7% of patients. Anticoagulant treatment lasted 653 months in >90% of patients and was extended in patients with proximal deep vein thrombosis because considered at high risk of recurrence or had thrombophilic abnormalities. d-dimer testing, assessment of residual thrombus, and patient preference were also indicated among the criteria influencing the decision. In conclusion, Italian doctors stuck to the minimum 3 months AT after VTE, while the secondary or unprovoked nature of the event was not seen as the prevalent factor influencing AT duration which instead was the result of a complex and multifactorial evaluation of each patient

    Metal Absorption Systems in Spectra of Pairs of QSOs

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    We present the first large sample of absorption systems in paired QSOs consisting of 691 absorption systems in the spectra of 310 QSOs including 170 pairings. All these absorption systems have metal lines, usually C IV or Mg II. We see 17 cases of absorption in one line-of-sight within 200 km/s (1 Mpc) of absorption in the paired line-of-sight with the probability at least approx 50% at 100kpc, declining rapidly to 23% at 100 - 200 kpc. We detect clustering on 0.5Mpc scales and see a hint of the "fingers of God" redshift-space distortion. The distribution matches absorbers arising in galaxies at z=2 with a normal correlation function and systematic infall velocities but unusually low random pair-wise velocity differences. Absorption in gas flowing out from galaxies at a mean velocity of 250 km/s would produce vastly more elongation than we see. The UV absorption from fast winds that Adelberger et al. 2005 see in spectra of LBGs is not representative of the absorption that we see. Either the winds are confined to LBGs, or they can not extend to 40 kpc with large velocities, while continuing to make UV absorption we see, implying most metals were in place in the IGM long before z=2. Separately, when we examine the absorption seen when a sight line passes a second QSO, we see 19 absorbers within 400 km/s of the partner QSO. The probability of seeing absorption is approximately constant for impact parameters 0.1 - 1.5 Mpc. Perhaps we do not see a rapid rise in the probability at small impact parameters because the UV from QSOs destroys some absorbers near to the QSOs. The 3D distribution of 64 absorbers around 313 QSOs is to first order isotropic, with just a hint of the anisotropy expected if the QSO UV emission is beamed, or alternatively QSOs might emit UV isotropically but for a surprisingly short time of only 0.3Myr.Comment: 36 pages with 25 figures and 10 Tables Submited to MNRA

    Does social cognition change? Evidence after 4 years from the Italian Network for Research on Psychoses

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    Background Deficits in social cognition (SC) are significantly related to community functioning in schizophrenia (SZ). Few studies investigated longitudinal changes in SC and its impact on recovery. In the present study, we aimed: (a) to estimate the magnitude and clinical significance of SC change in outpatients with stable SZ who were assessed at baseline and after 4 years, (b) to identify predictors of reliable and clinically significant change (RCSC), and (c) to determine whether changes in SC over 4 years predicted patient recovery at follow-up. Methods The reliable change index was used to estimate the proportion of true change in SC, not attributable to measurement error. Stepwise multiple logistic regression models were used to identify the predictors of RCSC in a SC domain (The Awareness of Social Inference Test [TASIT]) and the effect of change in TASIT on recovery at follow-up. Results In 548 participants, statistically significant improvements were found for the simple and paradoxical sarcasm of TASIT scale, and for the total score of section 2. The reliable change index was 9.8. A cut-off of 45 identified patients showing clinically significant change. Reliable change was achieved by 12.6% and RCSC by 8% of participants. Lower baseline TASIT sect. 2 score predicted reliable improvement on TASIT sect. 2. Improvement in TASIT sect. 2 scores predicted functional recovery, with a 10-point change predicting 40% increase in the probability of recovery. Conclusions The RCSC index provides a conservative way to assess the improvement in the ability to grasp sarcasm in SZ, and is associated with recovery

    A cluster randomised controlled trial of the clinical and cost-effectiveness of a 'whole systems' model of self-management support for the management of long- term conditions in primary care: trial protocol

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    BackgroundPatients with long-term conditions are increasingly the focus of quality improvement activities in health services to reduce the impact of these conditions on quality of life and to reduce the burden on care utilisation. There is significant interest in the potential for self-management support to improve health and reduce utilisation in these patient populations, but little consensus concerning the optimal model that would best provide such support. We describe the implementation and evaluation of self-management support through an evidence-based 'whole systems' model involving patient support, training for primary care teams, and service re-organisation, all integrated into routine delivery within primary care.MethodsThe evaluation involves a large-scale, multi-site study of the implementation, effectiveness, and cost-effectiveness of this model of self-management support using a cluster randomised controlled trial in patients with three long-term conditions of diabetes, chronic obstructive pulmonary disease (COPD), and irritable bowel syndrome (IBS). The outcome measures include healthcare utilisation and quality of life. We describe the methods of the cluster randomised trial.DiscussionIf the 'whole systems' model proves effective and cost-effective, it will provide decision-makers with a model for the delivery of self-management support for populations with long-term conditions that can be implemented widely to maximise 'reach' across the wider patient population.Trial registration numberISRCTN: ISRCTN9094004
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