High time-resolution observations of the Vela pulsar

We present high time resolution observations of single pulses from the Vela pulsar (PSR B0833-45) made with a baseband recording system at observing frequencies of 660 and 1413 MHz. We have discovered two startling features in the 1413 MHz single pulse data. The first is the presence of giant micro-pulses which are confined to the leading edge of the pulse profile. One of these pulses has a peak flux density in excess of 2500 Jy, more than 40 times the integrated pulse peak. The second new result is the presence of a large amplitude gaussian component on the trailing edge of the pulse profile. This component can exceed the main pulse in intensity but is switched on only relatively rarely. Fluctutation spectra reveal a possible periodicity in this feature of 140 pulse periods. Unlike the rest of the profile, this component has low net polarization and emits predominantly in the orthogonal mode. This feature appears to be unique to the Vela pulsar. We have also detected microstructure in the Vela pulsar for the first time. These same features are present in the 660 MHz data. We suggest that the full width of the Vela pulse profile might be as large as 10 ms but that the conal edges emit only rarely.Comment: 6 pages, 5 figures, In Press with ApJ Letter

Identification of single-site gold catalysis in acetylene hydrochlorination

There remains considerable debate over the active form of gold under operating conditions of a recently validated gold catalyst for acetylene hydrochlorination. We have performed an in situ x-ray absorption fine structure study of gold/carbon (Au/C) catalysts under acetylene hydrochlorination reaction conditions and show that highly active catalysts comprise single-site cationic Au entities whose activity correlates with the ratio of Au(I):Au(III) present. We demonstrate that these Au/C catalysts are supported analogs of single-site homogeneous Au catalysts and propose a mechanism, supported by computational modeling, based on a redox couple of Au(I)-Au(III) species. View Full Tex

Microevolutionary traits and comparative population genomics of the emerging pathogenic fungus Cryptococcus gattii

Emerging fungal pathogens cause an expanding burden of disease across the animal kingdom, including a rise in morbidity and mortality in humans. Yet, we currently have only a limited repertoire of available therapeutic interventions. A greater understanding of the mechanisms of fungal virulence and of the emergence of hypervirulence within species is therefore needed for new treatments and mitigation efforts. For example, over the past decade, an unusual lineage of Cryptococcus gattii, which was first detected on Vancouver Island, has spread to the Canadian mainland and the Pacific Northwest infecting otherwise healthy individuals. The molecular changes that led to the development of this hypervirulent cryptococcal lineage remain unclear. To explore this, we traced the history of similar microevolutionary events that can lead to changes in host range and pathogenicity. Here, we detail fine-resolution mapping of genetic differences between two highly related Cryptococcus gattii VGIIc isolates that differ in their virulence traits (phagocytosis, vomocytosis, macrophage death, mitochondrial tubularization and intracellular proliferation). We identified a small number of single site variants within coding regions that potentially contribute to variations in virulence. We then extended our methods across multiple lineages of C. gattii to study how selection is acting on key virulence genes within different lineages. This article is part of the themed issue ‘Tackling emerging fungal threats to animal health, food security and ecosystem resilience’

First detection of galaxy-galaxy-galaxy lensing in RCS. A new tool for studying the matter environment of galaxy pairs

The weak gravitational lensing effect, small coherent distortions of galaxy images by means of a gravitational tidal field, can be used to study the relation between the matter and galaxy distribution. In this context, weak lensing has so far only been used for considering a second-order correlation function that relates the matter density and galaxy number density as a function of separation. We implement two new, third-order correlation functions that have recently been suggested in the literature, and apply them to the Red-Sequence Cluster Survey. We demonstrate that it is possible, even with already existing data, to make significant measurements of third-order lensing correlations. We develop an optimised computer code for the correlation functions. To test its reliability a set of tests are performed. The correlation functions are transformed to aperture statistics, which allow easy tests for remaining systematics in the data. In order to further verify the robustness of our measurement, the signal is shown to vanish when randomising the source ellipticities. Finally, the lensing signal is compared to crude predictions based on the halo-model. On angular scales between roughly 1 arcmin and 11 arcmin a significant third-order correlation between two lens positions and one source ellipticity is found. We discuss this correlation function as a novel tool to study the average matter environment of pairs of galaxies. Correlating two source ellipticities and one lens position yields a less significant but nevertheless detectable signal on a scale of 4 arcmin. Both signals lie roughly within the range expected by theory which supports their cosmological origin.[ABRIDGED]Comment: 15 pages, 12 figures, accepted by A&A; minor change

Stripe formation: A quantum critical point for cuprate superconductors

We discuss the effects of a quantum critical point located nearby optimum doping and related to local charge segregation (stripe phase). The fluctuations in the critical region produce at the same time a strong pairing mechanism and a non-Fermi liquid behavior in the normal phase above the superconducting critical temperature. Superconductivity is a stabilizing mechanism against charge ordering, i.e. the incommensurate charge density wave quantum critical point is unstable with respect to superconductivity. A complete scenario for the cuprates is presented.Comment: Proceedings of the Cape Cod Conference on "Spectroscopies in Novel Superconductors, SNS 97", to appear on J. Phys. and Chem. of Solid

Analytic Detection Thresholds for Measurements of Linearly Polarized Intensity Using Rotation Measure Synthesis

A fully analytic statistical formalism does not yet exist to describe radio-wavelength measurements of linearly polarized intensity that are produced using rotation measure synthesis. In this work we extend the analytic formalism for standard linear polarization, namely that describing measurements of the quadrature sum of Stokes Q and U intensities, to the rotation measure synthesis environment. We derive the probability density function and expectation value for Faraday-space polarization measurements for both the case where true underlying polarized emission is present within unresolved Faraday components, and for the limiting case where no such emission is present. We then derive relationships to quantify the statistical significance of linear polarization measurements in terms of standard Gaussian statistics. The formalism developed in this work will be useful for setting signal-to-noise ratio detection thresholds for measurements of linear polarization, for the analysis of polarized sources potentially exhibiting multiple Faraday components, and for the development of polarization debiasing schemes.Comment: 14 pages, 6 figures, accepted for publication in MNRA

Optical observations of close binaries with the Mark III Stellar Interferometer

For the first time, four spectroscopic binaries have been directly resolved with the Mark III Stellar Interferometer. Observations in 1988 and 1989 were analyzed, and visual orbits for four binaries have been determined. The semimajor axes for β Tri, α Equ, α And and β Ari are approximately 0.008 arcsec, 0.012 arcsec, 0.024 arcsec and 0.037 arcsec, respectively. The magnitude differences between two components are 0.5, 0.7, 1.8 and 2.6 mag, respectively. All of the orbital elements for α And and β Ari were determined from interferometric data only, and agree well with spectroscopic observations. Predictions of relative position between the two components for these binaries are consistent with the measurements to less than 0.001 arcsec. Combined with data from spectroscopy, masses and distance for the double-lined spectroscopic binary β Ari are derived, and the results indicate that both components of β Ari agree well with the empirical mass-luminosity relation

A Multi-Institutional Study on the Safety and Efficacy of Specimen Morcellation After Laparoscopic Radical Nephrectomy for Clinical Stage T1 or T2 Renal Cell Carcinoma

Abstract Introduction and Objective: Specimen morcellation during laparoscopic radical nephrectomy (LRN) for renal cell carcinoma (RCC) is controversial. We seek to evaluate the safety and efficacy of specimen morcellation and LRN for treatment of presumed malignant renal lesions. Methods: We retrospectively reviewed all patients who underwent LRN at three academic institutions from 1996 to 2007. One hundred eighty-eight patients underwent specimen morcellation after LRN for enhancing solid or cystic renal masses. Results: LRN was successfully performed on all the patients. Patient age ranged from 36 to 94. One hundred sixty-seven patients were in clinical stage T1, 19 patients T2, and unknown in two. The specimen was manually morcellated within a Cook Lap Sac or Endocatch II bag under laparoscopic or direct observation. On histological review of morcellated specimens, 165 patients were confirmed to have RCC, 17 had an oncocytoma, and 2 had benign cysts. At least 13 patients with RCC were pathologically upgraded to stage T3. Mean operative time was 225 minutes (range 94-650). Mean hospital stay was 2.5 days (range 1-8). In patients with RCC, 11 developed recurrent disease with mean follow-up of 21 months (range 0.3-111). In one patient, a port site recurrence occurred in concert with renal fossa and lymph node metastases. Conclusions: Intracorporeal mechanical morcellation after LRN appears to be safe and effective in clinical stage T1 and T2 RCC. This supports the use of morcellation as an alternative for intact specimen removal in properly selected patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78157/1/end.2009.0387.pd

VR/AR and hearing research: current examples and future challenges

A well-known issue in clinical audiology and hearing research is the level of abstraction of traditional experimental assessments and methods, which lack ecological validity and differ significantly from real-life experiences, often resulting in unreliable outcomes. Attempts to deal with this matter by, for example, performing experiments in real-life contexts, can be problematic due to the difficulty of accurately identifying control-specific parameters and events. Virtual and augmented reality (VR/AR) have the potential to provide dynamic and immersive audiovisual experiences that are at the same time realistic and highly controllable. Several successful attempts have been made to create and validate VR-based implementations of standard audiological and linguistic tests, as well as to design procedures and technologies to assess meaningful and ecologically-valid data. Similarly, new viewpoints on auditory perception have been provided by looking at hearing training and auditory sensory augmentation, aiming at improving perceptual skills in tasks such as speech understanding and sound-source localisation. In this contribution, we bring together researchers active in this domain. We briefly describe experiments they have designed, and jointly identify challenges that are still open and common approaches to tackle the