Efficient, high-power operation of CW Yb:YAG and Q-switched Nd:YAG planar waveguide lasers

The planar waveguide gain medium o ers a good approach to creating a high- power lasers. Excellent thermal properties allow for lasers with good beam-quality and high-e ciency. A Neodymium doped YAG planar waveguide laser was actively Q-switched using a hybrid unstable resonator and acousto-optic modulator. A Yt- terbium doped YAG planar waveguide laser was side-pumped using two laser diode stacks with a total of 800 W incident pump power. The Nd:YAG planar waveguide laser has a core 200 um thick and was face pumped with ten laser diode bars. Q-switching was achieved through the use of a new hybrid unstable resonator con guration providing high-speed modulation of the laser cavity. The laser produced 100 W of average power with a pulse repetition rate of 100 kHz, giving 1 mJ pulses with 50 ns duration. Shorter 15 ns pulses were achieved with 4.5 mJ pulse energy at lower pulse repetition rates. The Yb:YAG planar waveguide laser has a 150 um core thickness, side pumped by two 430 W, six-bar diode laser stacks. Each diode stack has a custom phase- plate, correcting for collimation errors and lens aberrations. These gave a line focus matching the dimensions of the waveguide core with an incident intensity on each side of approximately 22 kWcm-2. Ray tracing of spontaneous emission within the waveguide core shows side facet angles of 7 and 20 were required to minimise ASE and parasitic oscillations within the waveguide core. A technique to image the uorescence from the Yb:YAG waveguide core has been developed. This technique allows for easy alignment of the pump lasers to the waveg- uide core and measurement of the pump intensity pro le throughout the planar waveg- uide. This technique showed single-sided pumping to follow Beer's law, and with double-sided pumping considerably improved the pump uniformity. A diode laser probe was used to measure the gain present within the waveguide. The small signal gain coe cient was shown to be 1 cm-1 with a uniform pro le across the width of the waveguide when pumped to saturation. This highlights the potential of operating the planar waveguide laser as an e cient ampli er. High-power high-e ciency operation of the Yb:YAG planar waveguide laser was achieved through the use of a hybrid stable waveguide resonator. Output power of 400 W was extracted in a multi-mode beam with a slope e ciency of 75%. This result represents the highest output power from a diode-pumped solid-state planar waveguide laser to date

Study of diffusion weighted MRI as a predictive biomarker of response during radiotherapy for high and intermediate risk squamous cell cancer of the oropharynx: The MeRInO study

Introduction and background: A significant proportion of patients with intermediate and high risk squamous cell cancer of the oropharynx (OPSCC) continue to relapse locally despite radical chemoradiotherapy (CRT). The toxicity of the current combination of intensified dose per fraction radiotherapy and platinum based chemotherapy limits further uniform intensification. If a predictive biomarker for outcomes from CRT can be identified during treatment then individualised and adaptive treatment strategies may be employed. Methods/design: The MeRInO study is a prospective observational imaging study of patients with intermediate and high risk, locally advanced OPSCC receiving radical RT or concurrent CRT Patients undergo diffusion weighted MRI prior to treatment (MRI_1) and during the third week of RT (MRI_2). Apparent diffusion coefficient (ADC) measurements will be made on each scan for previously specified target lesions (primary and lymph nodes) and change in ADC calculated. Patients will be followed up and disease status for each target lesion noted. The primary aim of the MeRInO study is to determine the threshold change in ADC from baseline to week 3 of RT that may identify the sub-group of non-responders during treatment. Discussion: The use of DW-MRI as a predictive biomarker during RT for SCC H&N is in its infancy but studies to date have found that response to treatment may indeed be predicted by comparison of DW-MRI carried out before and during treatment. However, previous studies have included all sub-sites and biological sub-types. Establishing ADC thresholds that predict for local failure is an essential step towards using DW-MRI to improve the therapeutic ratio in treating SCC H&N. This would be done most robustly in a specific H&N sub-site and in sub-types with similar biological behaviour. The MeRInO study will help establish these thresholds in OPSCC

An ALMA survey of Sub-millimeter Galaxies in the Extended Chandra Deep Field South: Physical properties derived from ultraviolet-to-radio modelling

[abridged] The ALESS survey has followed-up a sample of 122 sub-millimeter sources in the Extended Chandra Deep Field South at 870um with ALMA, allowing to pinpoint the positions of sub-millimeter galaxies (SMGs) to 0.3'' and to find their precise counterparts at different wavelengths. This enabled the first compilation of the multi-wavelength spectral energy distributions (SEDs) of a statistically reliable survey of SMGs. In this paper, we present a new calibration of the MAGPHYS modelling code that is optimized to fit these UV-to-radio SEDs of z>1 star-forming galaxies using an energy balance technique to connect the emission from stellar populations, dust attenuation and dust emission in a physically consistent way. We derive statistically and physically robust estimates of the photometric redshifts and physical parameters for the ALESS SMGs. We find that they have a median stellar mass $M_\ast=(8.9\pm0.1)\times10^{10} M_\odot$, SFR$=280\pm70 M_\odot$/yr, overall V-band dust attenuation $A_V=1.9\pm0.2$ mag, dust mass M_\rm{dust}=(5.6\pm1.0)\times10^8 M_\odot, and average dust temperature Tdust~40 K. The average intrinsic SED of the ALESS SMGs resembles that of local ULIRGs in the IR range, but the stellar emission of our average SMG is brighter and bluer, indicating lower dust attenuation, possibly because they are more extended. We explore how the average SEDs vary with different parameters, and we provide a new set of SMG templates. To put the ALESS SMGs into context, we compare their stellar masses and SFRs with those of less actively star-forming galaxies at the same redshifts. At z~2, about half of the SMGs lie above the star-forming main sequence, while half are at the high-mass end of the sequence. At higher redshifts (z~3.5), the SMGs tend to have higher SFR and Mstar, but the fraction of SMGs that lie significantly above the main sequence decreases to less than a third.Comment: 22 pages, 14 figures, 2 tables. Accepted for publication in the Astrophysical Journal. The new MAGPHYS model libraries used in this paper will appear in www.iap.fr/magphys. The SMG SED templates shown in Section 6.1 are available at http://astronomy.swinburne.edu.au/~ecunha/ecunha/SED_Templates.htm

Complete Genome Sequence and Comparative Metabolic Profiling of the Prototypical Enteroaggregative Escherichia coli Strain 042

Background \ud Escherichia coli can experience a multifaceted life, in some cases acting as a commensal while in other cases causing intestinal and/or extraintestinal disease. Several studies suggest enteroaggregative E. coli are the predominant cause of E. coli-mediated diarrhea in the developed world and are second only to Campylobacter sp. as a cause of bacterial-mediated diarrhea. Furthermore, enteroaggregative E. coli are a predominant cause of persistent diarrhea in the developing world where infection has been associated with malnourishment and growth retardation. \ud \ud Methods \ud In this study we determined the complete genomic sequence of E. coli 042, the prototypical member of the enteroaggregative E. coli, which has been shown to cause disease in volunteer studies. We performed genomic and phylogenetic comparisons with other E. coli strains revealing previously uncharacterised virulence factors including a variety of secreted proteins and a capsular polysaccharide biosynthetic locus. In addition, by using Biolog™ Phenotype Microarrays we have provided a full metabolic profiling of E. coli 042 and the non-pathogenic lab strain E. coli K-12. We have highlighted the genetic basis for many of the metabolic differences between E. coli 042 and E. coli K-12. \ud \ud Conclusion \ud This study provides a genetic context for the vast amount of experimental and epidemiological data published thus far and provides a template for future diagnostic and intervention strategies

UWE - Celebrating Bristol Green Capital 2015 activities catalogue

This catalogue showcases and celebrates examples of the work of the hundreds of UWE staff and students who contributed to Bristol Green Capital 2015

UWE Celebrating Bristol Green Capital 2015 - Activities portfolio (supporting document for UWE Celebrating Bristol Green Capital 2015 activities catalogue)

This Activities Portfolio details projects, events and initiatives which represent the work of hundreds of UWE staff and students during Bristol's year as European Green Capital in 2015. It is the working file to accompany the UWE Green Capital 2015 Activities Catalogue

An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South : The Redshift Distribution and Evolution of Submillimeter Galaxies

Accepted by ApJ. 45 pages, 16 figuresWe present the first photometric redshift distribution for a large unbiased sample of 870um selected submillimeter galaxies (SMGs) with robust identifications based on observations with the Atacama Large Millimeter Array (ALMA). In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band, optical-near-infrared, photometry. We model the Spectral Energy Distributions (SEDs) for these 77 SMGs, deriving a median photometric redshift of z=2.3+/-0.1. The remaining 19 SMGs have insufficient optical or near-infrared photometry to derive photometric redshifts, but a stacking analysis of IRAC and Herschel observations confirms they are not spurious. Assuming these sources have an absolute H-band magnitude distribution comparable to that of a complete sample of z~1-2 SMGs, we demonstrate that the undetected SMGs lie at higher redshifts, raising the median redshift for SMGs to z=2.5+/-0.2. More critically we show that the proportion of galaxies undergoing an SMG phase at z>3 is 35+/-5% of the total population. We derive a median stellar mass for SMGs of Mstar=(8+/-1)x10^10Mo, but caution that there are significant systematic uncertainties in our stellar mass estimate, up to x5 for individual sources. We compare our sample of SMGs to a volume-limited, morphologically classified sample of ellipticals in the local Universe. Assuming the star formation activity in SMGs has a timescale of ~100Myr we show that their descendants at z~0 would have a space density and M_H distribution which are in good agreement with those of local ellipticals. In addition the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.Peer reviewe

An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South : The Redshift Distribution and Evolution of Submillimeter Galaxies

Accepted by ApJ. 45 pages, 16 figuresWe present the first photometric redshift distribution for a large unbiased sample of 870um selected submillimeter galaxies (SMGs) with robust identifications based on observations with the Atacama Large Millimeter Array (ALMA). In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band, optical-near-infrared, photometry. We model the Spectral Energy Distributions (SEDs) for these 77 SMGs, deriving a median photometric redshift of z=2.3+/-0.1. The remaining 19 SMGs have insufficient optical or near-infrared photometry to derive photometric redshifts, but a stacking analysis of IRAC and Herschel observations confirms they are not spurious. Assuming these sources have an absolute H-band magnitude distribution comparable to that of a complete sample of z~1-2 SMGs, we demonstrate that the undetected SMGs lie at higher redshifts, raising the median redshift for SMGs to z=2.5+/-0.2. More critically we show that the proportion of galaxies undergoing an SMG phase at z>3 is 35+/-5% of the total population. We derive a median stellar mass for SMGs of Mstar=(8+/-1)x10^10Mo, but caution that there are significant systematic uncertainties in our stellar mass estimate, up to x5 for individual sources. We compare our sample of SMGs to a volume-limited, morphologically classified sample of ellipticals in the local Universe. Assuming the star formation activity in SMGs has a timescale of ~100Myr we show that their descendants at z~0 would have a space density and M_H distribution which are in good agreement with those of local ellipticals. In addition the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.Peer reviewe

Neural stem cells restore myelin in a demyelinating model of Pelizaeus-Merzbacher disease

Pelizaeus-Merzbacher disease is a fatal X-linked leukodystrophy caused by mutations in the PLP1 gene, which is expressed in the CNS by oligodendrocytes. Disease onset, symptoms and mortality span a broad spectrum depending on the nature of the mutation and thus the degree of CNS hypomyelination. In the absence of an effective treatment, direct cell transplantation into the CNS to restore myelin has been tested in animal models of severe forms of the disease with failure of developmental myelination, and more recently, in severely affected patients with early disease onset due to point mutations in the PLP1 gene, and absence of myelin by MRI. In patients with a PLP1 duplication mutation, the most common cause of Pelizaeus-Merzbacher disease, the pathology is poorly defined because of a paucity of autopsy material. To address this, we examined two elderly patients with duplication of PLP1 in whom the overall syndrome, including end-stage pathology, indicated a complex disease involving dysmyelination, demyelination and axonal degeneration. Using the corresponding Plp1 transgenic mouse model, we then tested the capacity of transplanted neural stem cells to restore myelin in the context of PLP overexpression. Although developmental myelination and axonal coverage by endogenous oligodendrocytes was extensive, as assessed using electron microscopy (n = 3 at each of four end points) and immunostaining (n = 3 at each of four end points), wild-type neural precursors, transplanted into the brains of the newborn mutants, were able to effectively compete and replace the defective myelin (n = 2 at each of four end points). These data demonstrate the potential of neural stem cell therapies to restore normal myelination and protect axons in patients with PLP1 gene duplication mutation and further, provide proof of principle for the benefits of stem cell transplantation for other fatal leukodystrophies with ‘normal’ developmental myelination

Long term (5 Year) safety of bronchial thermoplasty: Asthma Intervention Research (AIR) trial

<b>Background:</b> Bronchial thermoplasty (BT) is a bronchoscopic procedure that improves asthma control by reducing excess airway smooth muscle. Treated patients have been followed out to 5 years to evaluate long-term safety of this procedure. <br></br> <br></br> <b>Methods:</b> Patients enrolled in the Asthma Intervention Research Trial were on inhaled corticosteroids ≥200 μg beclomethasone or equivalent + long-acting-beta2-agonists and demonstrated worsening of asthma on long-acting-β2-agonist withdrawal. Following initial evaluation at 1 year, subjects were invited to participate in a 4 year safety study. Adverse events (AEs) and spirometry data were used to assess long-term safety out to 5 years post-BT. <br></br> <br></br> <b>Results:</b> 45 of 52 treated and 24 of 49 control group subjects participated in long-term follow-up of 5 years and 3 years respectively. The rate of respiratory adverse events (AEs/subject) was stable in years 2 to 5 following BT (1.2, 1.3, 1.2, and 1.1, respectively,). There was no increase in hospitalizations or emergency room visits for respiratory symptoms in Years 2, 3, 4, and 5 compared to Year 1. The FVC and FEV1 values showed no deterioration over the 5 year period in the BT group. Similar results were obtained for the Control group. <br></br><br></br> <b>Conclusions:</b> The absence of clinical complications (based on AE reporting) and the maintenance of stable lung function (no deterioration of FVC and FEV1) over a 5-year period post-BT in this group of patients with moderate to severe asthma support the long-term safety of the procedure out to 5 years