On Nichols algebras over PGL(2,q) and PSL(2,q)

We compute necessary conditions on Yetter-Drinfeld modules over the groups \mathbf{PGL}(2,q)=\mathbf{PGL}(2,\FF_q) and \mathbf{PSL}(2,q)=\mathbf{PSL}(2,\FF_q) to generate finite dimensional Nichols algebras. This is a first step towards a classification of pointed Hopf algebras with group of group-likes isomorphic to one of these groups. As a by-product of the techniques developed in this work, we prove that there is no non-trivial finite-dimensional pointed Hopf algebra over the Mathieu groups $M_{20}$ and $M_{21}=\mathbf{PSL}(3,4)$.Comment: Minor change

Arterial pathology in canine mucopolysaccharidosis-I and response to therapy.

Mucopolysaccharidosis-I (MPS-I) is an inherited deficiency of α-L-iduronidase (IdU) that causes lysosomal accumulation of glycosaminoglycans (GAG) in a variety of parenchymal cell types and connective tissues. The fundamental link between genetic mutation and tissue GAG accumulation is clear, but relatively little attention has been given to the morphology or pathogenesis of associated lesions, particularly those affecting the vascular system. The terminal parietal branches of the abdominal aorta were examined from a colony of dogs homozygous (MPS-I affected) or heterozygous (unaffected carrier) for an IdU mutation that eliminated all enzyme activity, and in affected animals treated with human recombinant IdU. High-resolution computed tomography showed that vascular wall thickenings occurred in affected animals near branch points, and associated with low endothelial shear stress. Histologically these asymmetric 'plaques' entailed extensive intimal thickening with disruption of the internal elastic lamina, occluding more than 50% of the vascular lumen in some cases. Immunohistochemistry was used to show that areas of sclerosis contained foamy (GAG laden) macrophages, fibroblasts and smooth muscle cells, with loss of overlying endothelial basement membrane and claudin-5 expression. Lesions contained scattered cells expressing nuclear factor-κβ (p65), increased fibronectin and transforming growth factor β-1 signaling (with nuclear Smad3 accumulation) in comparison to unaffected vessels. Intimal lesion development and morphology was improved by intravenous recombinant enzyme treatment, particularly with immune tolerance to this exogenous protein. The progressive sclerotic vasculopathy of MPS-I shares some morphological and molecular similarities to atherosclerosis, including formation in areas of low shear stress near branch points, and can be reduced or inhibited by intravenous administration of recombinant IdU

The Jet of 3C 17 and the Use of Jet Curvature as a Diagnostic of the X-ray Emission Process

We report on the X-ray emission from the radio jet of 3C 17 from Chandra observations and compare the X-ray emission with radio maps from the VLA archive and with the optical-IR archival images from the Hubble Space Telescope. X-ray detections of two knots in the 3C 17 jet are found and both of these features have optical counterparts. We derive the spectral energy distribution for the knots in the jet and give source parameters required for the various X-ray emission models, finding that both IC/CMB and synchrotron are viable to explain the high energy emission. A curious optical feature (with no radio or X-ray counterparts) possibly associated with the 3C 17 jet is described. We also discuss the use of curved jets for the problem of identifying inverse Compton X-ray emission via scattering on CMB photons.Comment: 6 pages, 6 figure (3 in color), 4 tables, ApJ accepte

Local authority responses to people with NRPF during the pandemic: research report

Migrants with ‘no recourse to public funds’ (NRPF) are at high risk of destitution due to their exclusion from most welfare benefits and statutory housing support. This is a longstanding issue that has been highlighted by campaigners, academics and the migration sector. This report examines how local authorities in England responded to people with NRPF during the COVID-19 pandemic. It highlights systemic issues with access to support for people with NRPF and shows how provision varied considerably across England (most notably in the case of single adults with NRPF who would not normally be eligible for support but were included in the COVID-19 homelessness response) and even within individual local authorities. The COVID-19 pandemic has made life significantly more difficult and precarious for people with NRPF. Many have lost income, employment and accommodation, while non-statutory support services have been forced to close. The number of people with NRPF in need of assistance to meet their basic needs has increased. Our research indicates that people with NRPF are more likely to become seriously ill or die if they contract COVID-19. Despite this, it has been difficult for many people with NRPF to access the help they need, including adequate food, shelter and subsistence support, during this public health crisis. Local authorities have statutory duties towards two categories of people with NRPF: families with ‘children in need’; and adults with care needs. There are, however, significant variations in how these duties are implemented, with many migrants in need of support unable to access their entitlements under normal (pre-pandemic) circumstances. A key problem in this area is that local authorities are not funded by central government to provide support to people with NRPF - an issue that has been consistently raised by rights advocates. This issue became more urgent during the pandemic as local authorities were called upon by central government to provide support to a third group of people with NRPF who would not normally be eligible for assistance: single homeless adults without care needs. Our research shows that, while some councils put in place effective emergency support for this group, the England-wide response of local authorities was frequently characterised by confusion, a lack of information about support options, the ‘gatekeeping’ of access to accommodation, and gaps in essential provision (e.g. food). Our research focuses on the period during which the UK was in ‘lockdown’. But the problems we highlight in this report have by no means come to an end. Local authorities continue to be underfunded and the destitution experienced by people with NRPF has not abated. It is unclear what will happen to homeless adults with NRPF who have no statutory entitlement to support as public- health concerns subside. Our research indicates that while some local authorities are trying to respond to this issue in a way that respects people’s rights and dignity, others do not want to continue to support people with NRPF, with a number planning to resort to so-called ‘voluntary returns’ or ‘reconnection’. In the view of many of our research participants, only an urgent end to the NRPF system can adequately address the problems that have been highlighted by COVID-19

Elliptic Solitons and Groebner Bases

We consider the solution of spectral problems with elliptic coefficients in the framework of the Hermite ansatz. We show that the search for exactly solvable potentials and their spectral characteristics is reduced to a system of polynomial equations solvable by the Gr\"obner bases method and others. New integrable potentials and corresponding solutions of the Sawada-Kotera, Kaup-Kupershmidt, Boussinesq equations and others are found.Comment: 18 pages, no figures, LaTeX'2

Triggered Star Formation in a Massive Galaxy at z=3.8: 4C41.17

Spectropolarimetric observations obtained with the W. M. Keck Telescope of the z=3.8 radio galaxy 4C41.17 show that the UV continuum emission from this galaxy, which is aligned with the radio axis, is unpolarized (P[2sigma] < 2.4%). This implies that scattered AGN light, which is generally the dominant contributor to the rest-frame UV emission in z~1 radio galaxies, is unlikely to be a major component of the UV flux from 4C41.17. The spectrum shows absorption lines that are similar to those detected in the spectra of the recently discovered population of star forming galaxies at z~2-3. A galaxian outflow may contribute partially to the low ionization absorption lines; however, the high velocity wings of the high ionization lines are unlikely to be dominated by a galaxian wind since the implied outflow mass is very large. The detection of stellar absorption lines, the shape of the SiIV profile, the unpolarized continuum, the inability of any AGN-related processes to account for the UV flux, and the similarity of the UV continuum spectra of 4C41.17 and the nearby starburst region NGC 1741B1 suggest that the UV light in 4C41.17 is dominated by young stars. If so, the implied star-formation rate is roughly 140-1100Msun/yr. We discuss the possibility that star formation in 4C41.17 was triggered by the radio source. Our data are consistent with the hypothesis that 4C41.17 is undergoing its major epoch of star formation at z~4, and that by z~1 it will have evolved to have spectral and morphological properties similar to those observed in known z~1 powerful radio galaxies.Comment: 28 pages (Latex text + figures); Accepted for publication in The Astrophysical Journal (Dec 1, 1997 issue

Characterizing Width Uniformity by Wave Propagation

This work describes a novel image analysis approach to characterize the uniformity of objects in agglomerates by using the propagation of normal wavefronts. The problem of width uniformity is discussed and its importance for the characterization of composite structures normally found in physics and biology highlighted. The methodology involves identifying each cluster (i.e. connected component) of interest, which can correspond to objects or voids, and estimating the respective medial axes by using a recently proposed wavefront propagation approach, which is briefly reviewed. The distance values along such axes are identified and their mean and standard deviation values obtained. As illustrated with respect to synthetic and real objects (in vitro cultures of neuronal cells), the combined use of these two features provide a powerful description of the uniformity of the separation between the objects, presenting potential for several applications in material sciences and biology.Comment: 14 pages, 23 figures, 1 table, 1 referenc

Improving the Control of Listeria monocytogenes on No-Nitrateor-Nitrite-Added (Natural or Organic) Frankfurters with Clean Label Antimicrobials

Consumers are critical of the ingredients used in the production of processed meat products. With the increased growth in natural and organic processed meats, suppliers have begun to offer clean label solutions to improve the safety of minimally processed foods. This study investigated the growth of Listeria monocytogenes on uncured, no-nitrate-or-nitrite-added frankfurters with or without clean-label antimicrobials, during a 120 day storage period. No-nitrate-or-nitrite-added brands with no antilisterial control measures exhibited a decreased lag time and shorter generation time for initiation of growth, resulting in a greater population of L. monocytogenes when compared to the sodium nitrite, sodium lactate/diacetate controls or alternatively cured products with clean label antimicrobials. Results indicate that clean label antimicrobials may serve as an effective intervention strategy for L. monocytogenes in the production of uncured, no-nitrate-or-nitrite-added (natural or organic) RTE meat products