Fault-Zone Waves Observed at the Southern Joshua Tree Earthquake Rupture Zone

Waveform and spectral characteristics of several aftershocks of the M 6.1 22 April 1992 Joshua Tree earthquake recorded at stations just north of the Indio Hills in the Coachella Valley can be interpreted in terms of waves propagating within narrow, low-velocity, high-attenuation, vertical zones. Evidence for our interpretation consists of: (1) emergent P arrivals prior to and opposite in polarity to the impulsive direct phase; these arrivals can be modeled as headwaves indicative of a transfault velocity contrast; (2) spectral peaks in the S wave train that can be interpreted as internally reflected, low-velocity fault-zone wave energy; and (3) spatial selectivity of event-station pairs at which these data are observed, suggesting a long, narrow geologic structure. The observed waveforms are modeled using the analytical solution of Ben-Zion and Aki (1990) for a plane-parallel layered fault-zone structure. Synthetic waveform fits to the observed data indicate the presence of NS-trending vertical fault-zone layers characterized by a thickness of 50 to 100 m, a velocity decrease of 10 to 15% relative to the surrounding rock, and a P-wave quality factor in the range 25 to 50

Derivation of an eigenvalue probability density function relating to the Poincare disk

A result of Zyczkowski and Sommers [J.Phys.A, 33, 2045--2057 (2000)] gives the eigenvalue probability density function for the top N x N sub-block of a Haar distributed matrix from U(N+n). In the case n \ge N, we rederive this result, starting from knowledge of the distribution of the sub-blocks, introducing the Schur decomposition, and integrating over all variables except the eigenvalues. The integration is done by identifying a recursive structure which reduces the dimension. This approach is inspired by an analogous approach which has been recently applied to determine the eigenvalue probability density function for random matrices A^{-1} B, where A and B are random matrices with entries standard complex normals. We relate the eigenvalue distribution of the sub-blocks to a many body quantum state, and to the one-component plasma, on the pseudosphere.Comment: 11 pages; To appear in J.Phys

Spectropolarimetry of the 3.4 micron absorption feature in NGC 1068

In order to test the silicate-core/organic-mantle model of galactic interstellar dust, we have performed spectropolarimetry of the 3.4 micron C-H bond stretch that is characteristic of aliphatic hydrocarbons, using the nucleus of the Seyfert 2 galaxy, NGC 1068, as a bright, dusty background source. Polarization calculations show that, if the grains in NGC 1068 had the properties assigned by the core-mantle model to dust in the galactic diffuse ISM, they would cause a detectable rise in polarization over the 3.4 micron feature. No such increase is observed. We discuss modifications to the basic core-mantle model, such as changes in grain size or the existence of additional non-hydrocarbon aligned grain populations, which could better fit the observational evidence. However, we emphasize that the absence of polarization over the 3.4 micron band in NGC 1068 - and, indeed, in every line of sight examined to date - can be readily explained by a population of small, unaligned carbonaceous grains with no physical connection to the silicates.Comment: ApJ, accepte

Hubble Diagrams of Type Ia Supernovae in the Near Infrared

From observations of 7 Type Ia supernovae obtained during the last four years at the Las Campanas and Cerro Tololo Inter-American Observatories, along with previous published data for 9 supernovae, we present JHK Hubble diagrams and derive absolute magnitudes at maximum light of 16 objects out to a redshift of 0.038. On the scale of H_0 = 72 km/s/Mpc we find mean absolute magnitudes at maximum of -18.57, -18.24, and -18.42 for J, H, and K, respectively, with 1-sigma uncertainties of the distributions of values of +/- 0.14, 0.18, and 0.12 mag. The data indicate no significant decline rate relations for the infrared. Thus, Type Ia SNe at maximum brightness appear to be standard candles in the infrared at the +/- 0.20 mag level or better. The minimum requirements for obtaining the distance to a Type Ia SN are: reasonably accurate values of Delta m_15(B) and T(B_max), and one night of infrared data in the -12 to +10 d window with respect to T(B_max).Comment: 15 pages, 3 figures, published in the Astrophysical Journal, vol. 602, pp. L81-L84 (20 February 2004). This version gives more credit where credit is du

Medicines reconciliation in primary care: a study evaluating the quality of medication-related information provided on discharge from secondary care

OBJECTIVES: Medicines reconciliation is an effective way of reducing errors at transitions of care. Much of the focus has been on medicines reconciliation at point of admission to hospital. Our objective was to evaluate medicines reconciliation after discharge from hospital by assessing the quality of information regarding medicines within discharge summaries and determining whether the information provided regarding medicines changes were acted on within 7 days of receiving the discharge information. METHODS: A retrospective collaborative evaluation of medicines-related discharge information by Clinical Commissioning Group (CCG) pharmacists using standardised data collection tools. Outcomes of interest included compliance with national minimum standards for medication-related information on discharge summaries, such as allergies, changes to medication regimen, minimum prescription standards, for example, dose, route, formulation and duration, and medicines reconciliation by the primary care team. Data were analysed centrally. RESULTS: 3 CCGs covering each of the four National Health Service regions in England participated in the study and submitted data for 1454 patients and 10 038 prescribed medicines. The majority of medication details were stated in accordance with standards with the exception of indication (11.7% compliance), formulation (60.3% compliance) and instructions of ongoing use (72.5% compliance). Documentation about changes was poor: 1550/3164 (49%) newly started medicines, 186/477 (39%) dose changes and 420/738 (57%) stopped medicines had a reason documented. Changes were not acted on within 7 days of receiving the discharge information for 12.5% of patients. CONCLUSIONS: Our evaluation revealed overall good compliance with discharge medication documentation standards, but a number of changes to medicines during hospitalisation were not fully communicated or documented on the discharge summary or actioned in the general practice after discharge

Wide-Field Infrared Imaging Polarimetry of the NGC 6334 Region: A Nest of Infrared Reflection Nebulae

We report the detection of eighteen infrared reflection nebulae (IRNe) in the $J$, $H$, & $Ks$ linear polarimetric observations of the NGC 6334 massive star-formation complex, of which 16 IRNe are new discoveries. Our images cover $\sim$180 square arcminutes, one of the widest near-infrared polarization data in star-formation regions so far. These IRNe are most likely associated with embedded young OB stars at different evolutionary phases, showing a variety of sizes, morphologies, and polarization properties, which can be divided into four categories. We argue the different nebula characteristics to be a possible evolutionary sequence of circumstellar structures around young massive stars.Comment: 4 pages, 1 figur