Why is the Fraction of Four-Image Radio Lens Systems So High?

We investigate the frequency of two- and four-image gravitational lens systems in the Jodrell-VLA Astrometric Survey (JVAS) and Cosmic Lens All-Sky Survey (CLASS), and the possible implications for dark matter halo properties. A simple lensing statistics model, which describes lens galaxies as singular isothermal ellipsoids with a projected axis ratio distribution derived from the surface brightness ellipticities of early-type galaxies in the Coma cluster, is ruled out at the 98% level since it predicts too few four-image lenses (quads). We consider a range of factors that may be increasing the frequency of radio quads, including external shear fields, mass distributions flatter than the light, shallow lensing mass profiles, finite core radii, satellite galaxies, and alterations to the luminosity function for faint flat-spectrum radio sources. We find that none of these mechanisms provide a compelling solution to the quad problem on their own while remaining consistent with other observational constraints.Comment: Final version. 27 pages, including 9 figs, minor typos corrected, ApJ in press (June 2001

Molecular and Cellular Analysis of the DMA Repair Defect in a Patient in Xeroderma Pigmentosum Complementation Group D Who Has the Clinical Features of Xeroderma Pigmentosum and Cockayne Syndrome

Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are quite distinct genetic disorders that are associated with defects in excision repair of UV-induced DNA damage. A few patients have been described previously with the clinical features of both disorders. In this paper we describe an individual in this category who has unusual cellular responses to UV light. We show that his cultured fibroblasts and lymphocytes are extremely sensitive to irradiation with UV-C, despite a level of nucleotide excision repair that is 30%-40% that of normal cells. The deficiency is assigned to the XP-D complementation group, and we have identified two causative mutations in the XPD gene: a gly→arg change at amino acid 675 in the allele inherited from the patient's mother and a -1 frameshift at amino acid 669 in the allele inherited from his father. These mutations are in the C-terminal 20% of the 760-amino-acid XPD protein, in a region where we have recently identified several mutations in patients with trichothiodystrophy.</p

Developing tools to promote culturally competent compassion, courage, and intercultural communication in healthcare

Background: Compassion is an important concept in healthcare, and in addition, care should be delivered in a culturally competent manner, taking into account the values, culture, and health beliefs of the individual. However, the training of nurses and other healthcare professionals may not adequately equip them to practice in a manner which is both compassionate and culturally competent. In this paper, we report on the development of three learning tools, designed to promote the skills and strengthen the capacity of nurses and healthcare professionals to provide culturally competent and compassionate care. Methods: The project involved the participation of six European countries in the development of three learning tools, covering culturally competent compassion, culturally competent courage, and intercultural communication. The principles which informed the methodology derive from the previous work on the Papadopoulos, Tilki and Taylor (PTT) model of transcultural nursing and cultural competence, and were also informed by the Intercultural Education of Nurses in Europe (IENE1 & IENE2) projects. Each partner country was required to produce one tool for each topic area, based on guidance provided by the project co-ordinator, leading to the development of eighteen tools in total. The tools were administered mainly to student nurses to test their feasibility. Results: The emerging tools contained important theoretical and practical components, whereby innovative learning methods and case studies were included. Student nurses enjoyed using the tools, and enjoyed their flexibility. The learning tools enabled students to become stimulated and to engage together leading to a positive learning experience. Discussion: The tools allow for a positive learning experience and reflection of good practice to take place. The flexibility and content of the tools allows for them to be of equal value to other healthcare professionals as well as nursing staff. Conclusion: The tools were initially utilised mainly with student nurses and were received with a positive response. Work is now in place to further implement the tools and evaluate the longer term effects among a range of healthcare professionals and service user health outcomes

Molecular and Cellular Analysis of the DMA Repair Defect in a Patient in Xeroderma Pigmentosum Complementation Group D Who Has the Clinical Features of Xeroderma Pigmentosum and Cockayne Syndrome

Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are quite distinct genetic disorders that are associated with defects in excision repair of UV-induced DNA damage. A few patients have been described previously with the clinical features of both disorders. In this paper we describe an individual in this category who has unusual cellular responses to UV light. We show that his cultured fibroblasts and lymphocytes are extremely sensitive to irradiation with UV-C, despite a level of nucleotide excision repair that is 30%-40% that of normal cells. The deficiency is assigned to the XP-D complementation group, and we have identified two causative mutations in the XPD gene: a gly→arg change at amino acid 675 in the allele inherited from the patient's mother and a -1 frameshift at amino acid 669 in the allele inherited from his father. These mutations are in the C-terminal 20% of the 760-amino-acid XPD protein, in a region where we have recently identified several mutations in patients with trichothiodystrophy.</p

Is the abundance of Faecalibacterium prausnitzii relevant to Crohn's disease?

Reports that bacteria within the Firmicutes phylum, especially the species Faecalibacterium prausnitzii, are less abundant in Crohn’s disease (CD) patients and supernatants from cultures of this bacterium are anti-inflammatory prompted the investigation of the possible correlations between the abundance of F.prausnitzii and the response to treatment in patients with gut diseases and healthy controls. In a randomized, double-blind trial, faeces were collected from healthy volunteers, and from patients with active CD, ulcerative colitis (UC) and irritable bowel syndrome before and after treatment. The levels of F. prausnitzii DNA in faecal suspensions were determined by PCR. Treatment by an elemental diet was effective, resulting in decreases in both the Harvey and Bradshaw index (P<0.001) and the concentrations of serum C-reactive protein (P<0.05). The total levels of F. prausnitzii in faecal samples from CD patients at presentation were lower than those in the other groups both before and after the treatment. There was no correlation between F. prausnitzii abundance and the severity of CD before treatment. Clinical improvement unexpectedly correlated with a significant decrease in the abundance of F. prausnitzii, especially the A2-165 subgroup (P<0.05). Our data suggest that a paucity of F. prausnitzii in the gastrointestinal microbial communities is likely to be a minor aetiological factor in CD: recovery following elemental diet is attributed to lower levels of gut flora

Fundamental Strings, Holography, and Nonlinear Superconformal Algebras

We discuss aspects of holography in the AdS_3 \times S^p near string geometry of a collection of straight fundamental heterotic strings. We use anomalies and symmetries to determine general features of the dual CFT. The symmetries suggest the appearance of nonlinear superconformal algebras, and we show how these arise in the framework of holographic renormalization methods. The nonlinear algebras imply intricate formulas for the central charge, and we show that in the bulk these correspond to an infinite series of quantum gravity corrections. We also makes some comments on the worldsheet sigma-model for strings on AdS_3\times S^2, which is the holographic dual geometry of parallel heterotic strings in five dimensions.Comment: 25 page

Toward the observation of interference effects in nonlinear Compton scattering

The photon spectrum from electrons scattering on multiple laser pulses exhibits interference effects not present for scattering on a single pulse. We investigate the conditions required for the experimental observation of these interference effects in electron-laser collisions, in particular analysing the roles of the detector resolution and the transverse divergence of the pump electron beam.Comment: 8 pages, 5 figure

Overview of Advanced LIGO Adaptive Optics

This is an overview of the adaptive optics used in Advanced LIGO (aLIGO), known as the thermal compensation system (TCS). The thermal compensation system was designed to minimize thermally-induced spatial distortions in the interferometer optical modes and to provide some correction for static curvature errors in the core optics of aLIGO. The TCS is comprised of ring heater actuators, spatially tunable CO$_{2}$ laser projectors and Hartmann wavefront sensors. The system meets the requirements of correcting for nominal distortion in Advanced LIGO to a maximum residual error of 5.4nm, weighted across the laser beam, for up to 125W of laser input power into the interferometer

Radial Velocity and Metallicity of the Globular Cluster IC4499 Obtained with AAOmega

We present radial velocity and metallicity measurements for the far-southern Galactic globular cluster IC4499. We selected several hundred target red giant stars in and around the cluster from the 2MASS point source catalog, and obtained spectra at the near-infrared calcium triplet using the AAOmega spectrograph. Observations of giants in globular clusters M4, M22, and M68 were taken to provide radial velocity and metallicity comparison objects. Based on velocity data we conclude that 43 of our targets are cluster members, by far the largest sample of IC4499 giants spectroscopically studied. We determine the mean heliocentric radial velocity of the cluster to be 31.5 plus or minus 0.4 km/s, and find the most likely central velocity dispersion to be 2.5 plus or minus 0.5 km/s. This leads to a dynamical mass estimate for the cluster of 93 plus or minus 37 thousand solar masses. We are sensitive to cluster rotation down to an amplitude of about 1 km/s, but no evidence for cluster rotation is seen. The cluster metallicity is found to be [Fe/H] = -1.52 plus or minus 0.12 on the Carretta-Gratton scale. The radial velocity of the cluster, previously highly uncertain, is consistent with membership in the Monoceros tidal stream, but also with a halo origin. The horizontal branch morphology of the cluster is slightly redder than average for its metallicity, but it is likely not unusually young compared to other clusters of the halo. The new constraints on the cluster kinematics and metallicity may give insight into its extremely high specific frequency of RR Lyrae stars.Comment: Accepted to MNRAS, 13 pages, 9 figure