Circumstellar Disks in the Outer Galaxy: the Star-Forming Region NGC 1893

It is still debated whether star formation process depends on environment. In particular it is yet unclear whether star formation in the outer Galaxy, where the environmental conditions are, theoretically, less conducive, occurs in the same way as in the inner Galaxy. We investigate the population of NGC1893, a young cluster ~3-4 Myr in the outer part of the Galaxy (galactic radius >11 Kpc), to explore the effects of environmental conditions on star forming regions. We present infrared observations acquired using the IRAC camera onboard the Spitzer Space Telescope and analyze the color-color diagrams to establish the membership of stars with excesses. We also merge this information with that obtained from Chandra ACIS-I observations, to identify the Class III population. We find that the cluster is very rich, with 242 PMS Classical T-Tauri stars and 7 Class 0/I stars. We identify 110 Class III candidate cluster members in the ACIS-I field of view. We estimate a disk fraction for NGC1893 of about 67%, similar to fractions calculated for nearby star forming regions of the same age. Although environmental conditions are unfavorable, star formation can clearly be very successful in the outer Galaxy, allowing creation of a very rich cluster like NGC1893.Comment: 10 pages,7 figures,4 table

Characterization of Mucus Glycoconjugates in Normal Human Conjunctiva by Lectins in Light Microscopy, Transmission and Scanning Electron Microscopy

Maintenance of tear film in normal conditions is dependent on 1) mucus layer integrity and 2) the presence and distribution of conjunctival epithelial cell microvilli. In the present work a new methodology has been developed to gain correlative information about microprojection assessment and mucus composition, from the same specimen, by Light Microscopy (LM), Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). We have characterized the glycosidic residues secreted by goblet cells in normal human conjunctiva, by means of four lectins (WGA, ConA, PNA and SBA), conjugated with FITC for LM and with colloidal gold for TEM and SEM. The cytochemical reactions were performed on histological sections of paraffin-embedded material and on semithin and ultrathin sections of both Epon embedded material directly processed for TEM and of blocks recovered from SEM and reprocessed for TEM. WGA, ConA, PNA and SBA receptors were found to be constituents of the mucus produced by goblet cells in human conjunctiva. The granules of the so-called second mucus system (SMS) cells were labelled mainly by WGA. A difference in the quality of glycoconjugates between goblet cells and SMS cells has been also demonstrated. Our results provide an improved method to evaluate alterations of tear film that occur in many conjunctival diseases

Scanning Electron Microscopy, X-Ray Microanalysis and Immunohistochemistry on Worn Soft Contact Lenses

The deposits accumulated on the surfaces of soft contact lenses are a cause of problems for the wearer of these lenses, as the deposits are never completely removed by the available washing solutions. Therefore it appears of interest to investigate the composition of these deposits. In this paper we review the major findings in the literature and, in addition, present our personal experience. We have studied new, continuously and daily worn soft contact lenses by scanning electron microscopy (SEM), X-ray microanalysis and immunohistochemistry. We have carefully evaluated preparative methods, and we can conclude that SEM and X-ray microanalysis are best carried out on unfixed, air-dried lenses. The deposits present consist mainly of mucus, especially on the tarsal side of the lenses. Chloride and potassium, coming from the tear fluid, as well as sulfur, derived from proteins, were found. Calcium was very rarely detected. IgG, IgA, IgE and C3c complement fractions were found only on the outer surfaces and not within the lens. We believe that the best characterization of the deposits is achieved by means of correlative techniques on the same lens. In fact, this approach integrates morphology and composition

X-ray emission in the Outer Galaxy: the Star Forming Region NGC 1893

A key issue of the star formation process is its independence from the environmental conditions. In particular, it is not clear whether star formation in the outer Galaxy occurs in the same way as in the inner Galaxy. We present preliminary results of the analysis of a ∼440 Ks ACIS‐Chandra observation of NGC1893, a young cluster (∼3–4 Myrs), far away from the Galactic Center with the aim to study star formation in the outer region of the Galaxy and investigate the coronal properties of the cluster stars. We detect more than 1000 X‐ray sources, most of which are likely cluster members. We present also a preliminary analysis of X‐ray variability of the cluster stars

Abundance variations and first ionization potential trends during large stellar flares

The Solar First Ionization Potential (FIP) effect, where low-FIP elements are enriched in the corona relative to the photosphere, while high-FIP abundances remain unchanged, has been known for a long while. High resolution X-ray spectroscopy has revealed that active stellar coronae show an opposite effect, which was labeled the Inverse-FIP (IFIP) effect. The correlation found between coronal activity and the FIP/IFIP bias suggested perhaps that flaring activity is involved in switching from FIP to IFIP. This work aims at a more systematic understanding of the FIP trends during stellar flares and complements an earlier study based on Chandra alone. The eight brightest X-ray flares observed with XMM-Newton are analyzed and compared with their respective quiescence states. Together with six previous flares observed with Chandra, this establishes the best currently available sample of flares. We look for abundance variations during the flare and their correlation with FIP. For that purpose, we define a new FIP bias measure. A trend is found where coronae that are IFIP biased in quiescence, during flares show a FIP bias with respect to their quiescence composition. This effect is reversed for coronae that are FIP biased in quiescence. The observed trend is thus consistent with chromospheric evaporation rather than with a FIP mechanism operating during flares. It also suggests that the quiescent IFIP bias is real and that the large flares are not the direct cause of the IFIP effect in stellar coronae.Comment: 12 pages, 6 figures, submitted to A&

Star Formation in the Outer Galaxy: Coronal Properties of NGC 1893

We investigate the X-ray properties of NGC 1893, a young cluster (~ 1-2 Myr) in the outer part of the Galaxy (galactic radius \geq 11 kpc) where we expect differences in the disk evolution and in the mass distribution of the stars, to explore the X-ray emission of its members and compare it with that of young stars in star forming regions near to the Sun. We analyze 5 deep Chandra ACIS-I observations with a total exposure time of 450 ks. Source events of the 1021 X-ray sources have been extracted with the IDL-based routine ACIS-Extract. Using spectral fitting and quantile analysis of X-ray spectra, we derive X-ray luminosities and compare the respective properties of Class II and Class III members. We also evaluate the variability of sources using the Kolmogorov-Smirnov test and we identify flares in the lightcurves. The X-ray luminosity of NGC 1893 X-ray members is in the range 10^29.5 - 10^31.5 erg/s. Diskless stars are brighter in X-rays than disk-bearing stars, given the same bolometric luminosity. We found that 34% of the 1021 lightcurves appear variable and that they show 0.16 flare per source, on average. Comparing our results with those relative to the Orion Nebula Cluster, we find that, accounting for observational biases, the X-ray properties of NGC 1893 and the Orion ones are very similar. The X-ray properties in NGC 1893 are not affected by the environment and the stellar population in the outer Galaxy may have the same coronal properties of nearby star forming regions. The X-ray luminosity properties and the X-ray luminosity function appear to be universal and can therefore be used for distance estimations and for determining stellar properties as already suggested by Feigelson and collaborators.Comment: 14 pages,13 figures, 4 tables,accepted for publication by Astronomy and Astrophysic

Issues and challenges in the application of Husserlian phenomenology to the Lived Experience of Hate Crime and Its Legal Aftermath

The field of hate crime research addresses the presence, sources and impact of particular types of expressions of prejudice, often perceived as particularly damaging and hurtful forms of interpersonal abuse and violence. Little, if any, credible academic research seeks to vindicate the specific racist, gendered and other vicious prejudices articulated by many perpetrators of hate crime. In turn, this raises the reflexive question of the possibilities of researchers themselves ever being able to adopt a truly "unprejudiced" approach to the presence of such damaging prejudices. Can this goal be realised without a researcher necessarily losing an experientially-grounded understanding of what these meanings, values and purposes have come to mean, and how they are themselves interpretatively re-constituted anew, including within the lived experience of victims, witnesses, police, prosecutors, judges and victim support workers? A possible philosophically-informed approach to the dilemmas posed by this topic is offered by Husserl's phenomenology. Husserl's perpetually unfinished philosophical methodology strives, with concerted if sometimes tragic reflective rigor, to "suspend," "bracket out" and "neutralise" those core presuppositions constitutive of the research field that typically pre-judge precisely whatever demands to be questioned and explored in a radically non-prejudicial manner. This study critically explores the possibilities, reflective stages and theoretical limitations of a sympathetically reconstructed Husserlian approach to hate crime, itself understood as a would-be qualitative "science of consciousness." It argues that despite its manifest tensions, gaps, ambiguities and internal contradictions, aspects of the Husserlian philosophical approach directed towards the different levels of experienced hate crime still retain the potential to both challenge and advance our understanding of this topic. It is the "instructive" part of "instructive failure" that this article highlights