855 research outputs found
Novel schemes for the optical manipulation of atoms and molecules
No full textThe range of atoms which can be cooled by lasers is limited to those which have a closed two level structure. Several schemes have been proposed which aim to extend this range by using coherent control of the particle momenta, but none have yet been demonstrated. We hope to implement these and other coherent manipulation schemes, and we begin with a system which is well understood and over which we can exert precise control. This thesis covers the design and construction of an experiment to demonstrate coherent manipulation of cold rubidium atoms collected in a magneto-optical trap. The lower hyperfine levels of these cold atoms very closely mimic the ideal two-level atom, and we use carefully crafted laser pulses to prepare, manipulate, and read their quantum state. The hyperfine levels are coupled using two fields whose frequency difference is equal to the hyperfine splitting. The way in which these Raman coupled levels can be used to emulate a two-level atom is explored, and the experimental apparatus used to create and control the driving fields is described in detail. The amplitude, frequency and phase of these fields is programmable, and complex manipulation schemes can be implemented merely by programming a computer. We have observed Raman transitions in the cold rubidium atoms, and the experimental methods used to detect these features amidst large experimental noise are discussed. Although we have not yet seen Rabi oscillations, we are confident that we can now have sufficient control to begin to implement simple interferometric sequences. However, there remain significant challenges if we are to coherently manipulate the momentum, and the prospects for such manipulation are discussed
Transmitted deletions of medial 5p and learning difficulties; Does the cadherin cluster only become penetrant when flanking genes are deleted?
No full textThe central portion of the short arm of chromosome 5 is unusual in that large, cytogenetically visible interstitial deletions segregate in families with and without phenotypic consequences. Here we present a family in which a transmitted interstitial deletion of 5p13.3 to 5p14.3 co-segregated with learning and/or behavioral difficulties in six family members. Facial dysmorphism was not striking but a father and daughter both had lacrimal fistulae. The deletion was 12.23?Mb in size (chr5:20,352,535–32,825,775) and contained fifteen known protein coding genes. Five of these (GOLPH3; MTMR12; ZFR; SUB1; and NPR3) and an ultra-conserved microRNA (hsa-miR-579) were present in an 883?kb candidate gene region in 5p13.3 that was deleted in the present family but not in previously reported overlapping benign deletions. Members of the cadherin precursor gene cluster, with brain specific expression, were deleted in both affected and benign deletion families. The candidate genes in 5p13.3 may be sufficient to account for the consistent presence or absence of phenotype in medial 5p deletions. However, we consider the possibility of position effects in which CDH6, and/or other cadherin genes, become penetrant when adjacent genes, or modifiers of gene expression, are also deleted. This could account for the absence of intellectual disability in benign deletions of the cadherin cluster, the cognitive phenotype in medial 5p deletion syndrome and the greater severity of intellectual disability in patients with cri-du-chat syndrome and deletions of 5p15 that extend into the region deleted in the present family
Virtual patients design and its effect on clinical reasoning and student experience : a protocol for a randomised factorial multi-centre study
No full textBackground
Virtual Patients (VPs) are web-based representations of realistic clinical cases. They are proposed as being an optimal method for teaching clinical reasoning skills. International standards exist which define precisely what constitutes a VP. There are multiple design possibilities for VPs, however there is little formal evidence to support individual design features. The purpose of this trial is to explore the effect of two different potentially important design features on clinical reasoning skills and the student experience. These are the branching case pathways (present or absent) and structured clinical reasoning feedback (present or absent).
Methods/Design
This is a multi-centre randomised 2x2 factorial design study evaluating two independent variables of VP design, branching (present or absent), and structured clinical reasoning feedback (present or absent).The study will be carried out in medical student volunteers in one year group from three university medical schools in the United Kingdom, Warwick, Keele and Birmingham. There are four core musculoskeletal topics. Each case can be designed in four different ways, equating to 16 VPs required for the research. Students will be randomised to four groups, completing the four VP topics in the same order, but with each group exposed to a different VP design sequentially. All students will be exposed to the four designs. Primary outcomes are performance for each case design in a standardized fifteen item clinical reasoning assessment, integrated into each VP, which is identical for each topic. Additionally a 15-item self-reported evaluation is completed for each VP, based on a widely used EViP tool. Student patterns of use of the VPs will be recorded.
In one centre, formative clinical and examination performance will be recorded, along with a self reported pre and post-intervention reasoning score, the DTI. Our power calculations indicate a sample size of 112 is required for both primary outcomes
Light-activated modulation and coupling in integrated polymer-liquid crystal systems
No full textWe explore the transfer of an incident light pattern onto the liquid crystal (LC) bulk in a photorefractive cell through an integrated photoconducting layer that modulates the electric field applied to the device. The electrical properties and the strength of modulation are investigated as a function of the incident light intensity as well as the frequency and amplitude of the applied voltage, for two LCs with very different electrical conductivity. A simplified electrical model of the cell is proposed, demonstrating that the LC conductivity is a key factor determining the beam-coupling strength
The three adventurers : a thrilling tale of the early days of Texas /
No full textAdvertisement on p. [2] of cover.Photographic portrait of author on p. [2] and illustrations on p. 6, 82, 229 and 353, signed by T.D. Bateman."Press of A.C. Baldwin & Sons, Austin, Texas"--P. [2] of cover.Mode of access: Internet
Sources and impacts of inorganic and organic fine sediment in salmonid spawning gravels in chalk rivers
No full textPoor salmonid spawning habitat due to excessive fine sediment inputs has been identified as a major factor limiting survival in chalk rivers. A lack of knowledge about the complex processes and factors affecting survival was the driver for this study and gaps in the research were identified concerning the sources of fine sediment and the impact organic material had on salmonid survival in chalk streams. Consequently the main objectives of this study were to characterise spawning habitat quality of a chalk catchment, assess the sources of sediments accumulating within artificial redds, describe the composition of organic sediments using emerging technology and to create a novel method to assess the sediment oxygen consumption of those sediments. Methods were based around a catchment wide field based monitoring programme, consisting of artificially constructed spawning gravels which allowed hyporheic measurements to be taken, and sediment analysis and sediment oxygen consumption methods were carried out using different laboratory methods. Spawning habitat characteristics of the chalk catchment were found to exhibit; low sediment accumulation rates although original levels of fine sediment were high, high organic matter content, variable intra-gravel flow and intra-gravel oxygen concentrations and groundwater influences. Primary sources of fine sediment accumulating in spawning gravels and suspended sediments were found to be attributed to catchment surface sources, namely pasture (50-68%) and arable (32-50%) using inorganic and organic parameters. Organic composition of redd gravels was found to be dominated by protein material rather than humic substances, the more commonly found fluorescent compound in freshwater systems and the sediment oxygen consumption of sediments varied throughout the catchment and was found to consume the greatest oxygen in <63?m size fraction. Application of sediment oxygen consumption rates to existing parameter based models that predict salmonid survival, highlighted the need to address the sensitivity of current models to rivers experiencing low sediment accumulation rates. Outcomes of this study further the knowledge of the sources, organic composition and sediment oxygen consumption capacity of fine sediments accumulating in spawning gravels which can lead to appropriate mitigation on chalk rivers to improve salmonid spawning habitat
Bayesian modelling of integrated data and its application to seabird populations
No full textIntegrated data analyses are becoming increasingly popular in studies of wild animal populations where two or more separate sources of data contain information about common parameters. Here we develop an integrated population model using abundance and demographic data from a study of common guillemots (Uria aalge) on the Isle of May, southeast Scotland. A state-space model for the count data is supplemented by three demographic time series (productivity and two mark-recapture-recovery (MRR)), enabling the estimation of prebreeder emigration rate - a parameter for which there is no direct observational data, and which is unidentifiable in the separate analysis of MRR data. A Bayesian approach using MCMC provides a flexible and powerful analysis framework.
This model is extended to provide predictions of future population trajectories. Adopting random effects models for the survival and productivity parameters, we implement the MCMC algorithm to obtain a posterior sample of the underlying process means and variances (and population sizes) within the study period. Given this sample, we predict future demographic parameters, which in turn allows us to predict future population sizes and obtain the corresponding posterior distribution. Under the assumption that recent, unfavourable conditions persist in the future, we obtain a posterior probability of 70% that there is a population decline of >25% over a 10-year period.
Lastly, using MRR data we test for spatial, temporal and age-related correlations in guillemot survival among three widely separated Scottish colonies that have varying overlap in nonbreeding distribution. We show that survival is highly correlated over time for colonies/age classes sharing wintering areas, and essentially uncorrelated for those with separate wintering areas. These results strongly suggest that one or more aspects of winter environment are responsible for spatiotemporal variation in survival of British guillemots, and provide insight into the factors driving multi-population dynamics of the species
‘It is not the consciousness of men that determines their existence, but their social existence that determines their consciousness’: The self and late capitalism in Amis’s Money and Ellis’s American Psycho
No full textThis dissertation examines two novels: Money (1984) by Martin Amis and American Psycho (1991) by Bret Easton Ellis. Written at the peak of the Reagan-Thatcher era, both feature central characters: Money’s John Self and American Psycho’s Patrick Bateman whose wealthy lives are wholly occupied with material excess, alcoholism, drugs and pornography. As the Reagan-Thatcher epoch lied within the postmodern period and thus witnessed the emergence of multinational capitalism and its consequences, this dissertation argues that both novels are sites of social and political critique, offering a vision as to what extent and in what ways late capitalism shapes and influences the characters’ senses of self. While analysing the rhetoric of postmodern satire employed in the two books and a wide range of postmodern theoretical perspectives, it also uses Marx’s theory of alienation as its groundwork and Baudrillard and Jameson’s postmodern theories its main methodological approaches, to discuss the characterisations of Self and Bateman and their interconnection with the world they live in. This dissertation aims to arrive at three goals: first, to demonstrate how the formations of Self and Bateman’s identities reflect the ideology of late capitalism; second, to point out the impacts of their fragmented identities on themselves and their relationships with others in their public and private lives; third, to draw a conclusion on the causes of self-destruction in Money, and social destruction in American Psycho
Directly transmitted 12.3 Mb deletion with a consistent phenotype in the variable 11q21-q22.3 region
No full textA phenotype is emerging for the proximal pair of G-dark bands in 11q (11q14.1 and q14.3) but not yet for the distal pair (11q22.1 and q22.3). A mother and daughter with the same directly transmitted 12.3-Mb interstitial deletion of 11q21q22.3 (GRCh37: 93,551,765-105,817,723) both had initial feeding difficulties and failure to thrive, speech delay, learning difficulties, and mild dysmorphism. Among 17 patients with overlapping deletions, developmental or speech delay, dysmorphism, hypotonia, intellectual disability or learning difficulties, short stature, and coloboma were each found in 2 or more. These results may provide the basis for a consistent phenotype for this region. Among the 53 deleted and additional breakpoint genes, CNTN5, YAP1, and GRI4 were the most likely candidates. Non-penetrance of haploinsufficient genes and dosage compensation among related genes may account for the normal cognition in the mother and variable phenotypes that can extend into the normal range.</p
A de novo 4q34 interstitial deletion of at least 9.3 Mb with no discernible phenotypic effect
No full textCytogenetically visible imbalances without phenotypic effect are still rare despite the extent of large-scale copy number variation in the normal population revealed by array CGH. Here we report on a phenotypically normal 30-year-old female with a de novo, cytogenetically visible, interstitial deletion of band 4q34. She was referred following three successive miscarriages, one of which was an intra-uterine death with subendocardial fibroelastosis and dilated cardiomyopathy. There was no other notable medical or family history, she was of normal intelligence and had no dysmorphic features. FISH and Array CGH with a customized 1 Mb BAC array showed that the deletion is a minimum of 9.3 and a maximum of 10.7 Mb in size, between 173 Mb in 4q34.1 and 182 Mb in 4q34.3. The deletion contains only 23 known coding genes giving a low average gene density of 2 genes/Mb. This case further illustrates that (1) sizeable imbalances can be associated with apparent phenotypic normality, (2) gene density is a better guide to possible phenotypic consequences than aberration size, and (3) it is not always safe to assume that de novo imbalances will be causal
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