Effective Screened Potentials of Strongly Coupled Semiclassical Plasma

The pseudopotentials of particle interaction of astrongly coupled semiclassical plasma, taking into account bothquantum-mechanical effects of diffraction at short distances andalso screening field effects at large distances are obtained. Thelimiting cases of potentials are considered.Comment: 15 pages, TeX, 7 figure

An Investigation of Agreement between Clinical Educators and Peers in Rating Speech Pathology Students’ Interview Skills

Peer assessment and feedback is being used more frequently in health science education as it has been shown to enhance self-directed learning. This study investigated the level of agreement between clinical educators and speech pathology student peers when rating students’ performance during standardised patient interviews. Participating in this study were 104 undergraduate speech pathology students and six clinical educators who were required to rate students’ foundation clinical skills on the Standardised Patient Interview Rating Scale (SPIRS). Students’ skills, including communication, interviewing and professional practice, were rated by a clinical educator and a peer. Data from two separate interviews in weeks 4 and 8 of a clinical placement were analysed to determine the agreement between clinical educators and peers in rating a student on individual items on the SPIRS. Results indicated that there were unacceptable agreement levels between clinical educators and peers in both opportunities of rating. Recommendations for improving agreement between peers and clinical educators were made including increasing explicit training with the rating tool, increased collaboration between clinical educators and student raters, and using peers with more clinical placement experience as raters. Further research is required to investigate the use of peer assessment for both formative and summative purposes in speech pathology student education

Public Attitudes About Normal and Pathological Grief

Determining public expectations of grief is an important contributor to the debate differentiating normal from pathological grief. An international sample of 348 participants was randomly allocated to 1 of 12 conditions comprising a bereavement vignette and self-report items measuring grief expectations and social distance. Participants expected grief to decrease steadily between 2 weeks and 6 months then stabilize; however, time did not affect social distance. Gender of the bereaved and circumstances of death did not influence expectations, but did interact to influence social distance. These factors must be accounted for in determining a deviation from the norm in diagnostic nosology

Students’ Perceptions of Simulation-Based Learning in Speech Pathology: A Pilot Study

Due to increased student numbers and workforce limitations, speech pathology students have fewer opportunities to develop skills in working with adult populations in traditional clinical placements.  Using simulation-based learning has proven to be advantageous in other disciplines. The use of simulation to develop clinical skills in speech pathology range of practice areas, including speech, language and swallowing in adults, has been less well researched. The aim of this study was to investigate students’ overall perceptions about simulation-based learning, particularly their confidence related to specific clinical skills and perceived anxiety about working with adult clients. Six final year speech pathology students enrolled in either a 4-year undergraduate or 2.5-year masters program participated in this research. Students engaged in five simulation-based learning activities across one day. Purposefully developed pre- and post- surveys were completed to explore students’ anxiety levels and perceptions of confidence regarding clinical skills across domains of foundation knowledge, case history, assessment, intervention, interaction and clinical reasoning, and anxiety levels. The Satisfaction with Simulation Experience (SSE) Scale was completed post-simulation experience. Students also participated in a focus group discussion following the simulation experience. Student median ratings of clinical skills improved from pre- to post-simulation across the six domains. All students reported that the simulation-based learning experience was valuable and reported increased levels of confidence and enhanced preparedness for their clinical placements. Findings from this study suggested that students value simulation-based learning and future research should explore learning outcomes from a longer, more intensive simulation program

Femtosecond optical parametric oscillators in the mid-infrared

The work described in this thesis is concerned with the development of self-modelocked Ti:sapphire lasers and femtosecond optical parametric oscillators based on periodically-poled rubidium titanyl arsenate and periodically-poled lithium niobate and operating in the near and mid-infrared. In Chapter 1 the theory of ultrashort pulse generation is explained with regard to the Ti:sapphire laser. The optical properties of Ti:sapphire are discussed along with the principles of laser oscillation and pulse generation. The techniques used to modelock the lasers used in the experimental work, which follows, are also considered. The second part of the chapter deals with typical measurement techniques for characterising femtosecond optical pulses from a laser or an OPO, including a detailed explanation of second harmonic generation autocorrelation. Chapter 1 concludes with a thorough description of frequency-resolved optical gating, the newest of these pulse characterisation techniques. In Chapter 2 the subject of nonlinear optics and the properties of nonlinear optical materials are discussed. Phasematching in nonlinear optical materials is explained along with the principle techniques for achieving this, including birefringent phasematching and quasi-phasematching. A review of techniques for periodically- poling nonlinear optical crystals is also given. The chapter concludes with a section on the optical effects of group velocity dispersion and self-phase modulation, that influence the output from an ultrashort pulse laser or OPO and describes methods for second and third-order dispersion compensation. Chapter 2 concludes the theory required to explain the experiments described in Chapters 3, 4, 5 and 6. Chapter 3 describes the operation and characterisation of two different Ti:sapphire laser systems involving different methods of dispersion compensation. The first laser produces 100 fs duration self-modelocked laser pulses and dispersion compensation is achieved by including a pair of prisms in the cavity. This laser system is discussed further in Chapter 5, where it is operated in conjunction with a Spectra Physics Millennia, as the pump source for an all-solid-state femtosecond OPO based on periodically-poled lithium niobate. A second laser system is described in Chapter 3, which produces self-modelocked pulses of ~15 fs duration and dispersion compensation is achieved by including chirped multilayer dielectric mirrors in the cavity. The subject matter that Chapter 4 is concerned with includes the operation and characterisation of a femtosecond OPO based on PPRTA. Ti:sapphire pump wavelength tuning and cavity-length tuning of the OPO are shown to produce wavelengths throughout the range 1.060 mum to 1.225 mum in the signal and 2.67 jam to 4.5 mum in the idler, with average output powers as high as 120 mW in the signal and 105 mW in the idler output. The effects of photorefractive damage are minimal and consequently this offers the possibility of room-temperature operation of the PPRTA- based OPO. Chapter 5 is concerned with the generation of longer idler wavelengths, in the region of 5 mum, from an all-solid-state OPO based on periodically-poled lithium niobate. The approach used with the PPRTA-based OPO is extended to PPLN and in Chapter 5, results are presented which show that the use of an all-solid-state Ti:sapphire pump source in combination with a PPLN-based OPO represents a robust source of high- repetition-rate femtosecond pulses in the mid-infrared at wavelengths out to ~5 mum. Significantly higher output powers in the signal and idler than previously reported are also measured. In Chapter 6 a similar PPLN-based OPO is described, with modifications to the cavity elements, to reduce the output pulse duration of the OPO. This system is pumped by a sub- 20 fs Ti:sapphire laser. A pulse duration of 175 fs is recorded for the signal at a wavelength of 1.07 mum. Output powers of 28 mW for the signal at 1.07 mum and 6.8 mW for the idler at 2.7 mum are also measured. The tuning range for the signal extends from 1.045 mum to 1.190 mum, and for the idler, extends from 2.57 mum to 3.67 mum

Rapid and sustained surface ocean acidification during the Paleocene-Eocene Thermal Maximum

The Paleocene-Eocene Thermal Maximum (PETM) has been associated with the release of several thousands of petagrams of carbon (Pg C) as methane and/or carbon dioxide into the ocean-atmosphere system within ~10 kyr, on the basis of the co-occurrence of a carbon isotope excursion (CIE), widespread dissolution of deep sea carbonates, and global warming. In theory, this rapid carbon release should have severely acidified the surface ocean, though no geochemical evidence has yet been presented. Using boron-based proxies for surface ocean carbonate chemistry, we present the first observational evidence for a drop in the pH of surface and thermocline seawater during the PETM. Planktic foraminifers from a drill site in the North Pacific (Ocean Drilling Program Site 1209) show a ~0.8‰ decrease in boron isotopic composition (δ11B) at the onset of the event, along with a 30–40% reduction in shell B/Ca. Similar trends in δ11B are present in two lower-resolution records from the South Atlantic and Equatorial Pacific. These observations are consistent with significant, global acidification of the surface ocean lasting at least 70 kyr and requiring sustained carbon release. The anomalies in the B records are consistent with an initial surface pH drop of ~0.3 units, at the upper range of model-based estimates of acidification

A view from the watershed

International audiencePapers by H. L. Penman, H. C. Pereira, J. E. Nash and M. Nixon presented at a one-day Symposium to mark the opening of the Institute of Hydrology's new building in 1973 and reprinted from Institute of Hydrology Report No. 20

Boron, carbon, and oxygen isotopic composition of brachiopod shells: Intra-shell variability, controls, and potential as a paleo-pH recorder

The boron isotopic composition of biogenic carbonates has been used to reconstruct seawater pH and atmospheric pCO2 on Pleistocene and Cenozoic timescales. Because of their excellent preservation and extensive fossil record throughout the Phanerozoic, brachiopods are a promising candidate for extending the boron isotope record as far back as the Cambrian. Here we present stable carbon, oxygen, and boron isotopic measurements of modern Terebratulid brachiopod calcite in comparison with environmental pH estimates calculated from oceanographic data. Geochemical transects along the length and depth of single shells confirm previously published trends in carbon and oxygen isotopic composition. In the outer surface (primary and outermost secondary layers), δ11B covaries with δ13C and δ18O, with more negative values in the outer and more positive values in the middle of the shell. However, δ11B deviates from δ13C and δ18O in the inner part of the secondary layer, where the δ13C and δ18O values are more positive and near equilibrium, whereas δ11B returns to more negative values. A comparison of different specimens of the species Terebratalia transversa (Sowerby, 1846) and Laqueus californianus (Küster, 1844) microsampled from the middle part of the fibrous secondary layer demonstrates a clear correlation to ambient pH with a sensitivity similar to other empirical calibration curves for cultured planktic foraminifers, corals, and inorganic calcite. The relationship in other species is less clear and significantly offset, necessitating the use of a single species or a cross-calibration method with other species in paleo-pH reconstructions

Differential Survival among Batches of Atlantic Cod (Gadus morhua L.) from Fertilisation through to Post-Metamorphosis

Aquaculture production of cod has decreased from over 20,000 tonnes in 2009 to less than 2,000 tonnes in 2014 and the industry faces many challenges, one of which is high and unpredictably variable mortality rates in the early life stages. Hence, full-cycle farming with hatchery produced juveniles is still considered unprofitable compared to fisheries and on-growing of wild cod. In the present study, potential batch differences in progeny survival of wild-caught, hatchery-spawned Faroe Bank cod (Gadus morhuaL.) were investigated at two defined periods during early life history; i) the embryo stage (60 day degrees post fertilisation) and ii) the fry stage (110 days post hatch), post metamorphosis. The fry stage experiment was conducted in three replicates (N= 300 per replicate), and a panel of three polymorphic microsatellite markers was used for parental analysis. Mean survival rate at the embryo stage was 69% (± 20% SD). Survival was positively associated with egg diameter (P< 0.01), explaining 90% of the variation in egg survival rates. The data were too scarce to conclude either way concerning a possible correlation between survival rates between the two periods (P< 0.10). Offspring from three batches (from a total of eight) dominated in the fry stage, contributing over 90% of the progeny, and results were consistent over all three replicate tanks. The skewed batch representation observed may be of relevance to the effective management of selective breeding programmes for cod