10,729 research outputs found
Wavelength tunable 10-GHz 3-ps pulse source using a dispersion decreasing fiber-based nonlinear optical loop mirror
No full textWe experimentally demonstrate the use of a dispersion decreasing fiber (DDF)-based nonlinear optical loop mirror (NOLM) for the generation of wavelength tunable soliton-like pulses at a repetition rate of 10 GHz. We compress ~12 ps Gaussian pulses from an electro-absorption modulator (EAM) (followed by 125 m of DCF for preliminary linear dispersion compensation) into 3 ps pedestal-free pulses using both high-order soliton compression and nonlinear switching effects within an 8.5 km DDF-based loop mirror. The output pulses from the DDF-based NOLM show considerable pedestal reduction compared to those obtained by directly compressing the EAM seed pulses via a single passage through the DDF. Wavelength tuning of the compressed pulses over a ~15 nm bandwidth (from 1541 to 1556 nm) is demonstrated without a significant increase in pulse duration or degradation in pulse quality
Cognitive deficits are associated with frontal and temporal lobe white matter lesions in middle-aged adults living in the community
No full textThe work was supported by the Leverhulme Trust and the British Academy and was funded by NHMRC of Australia Unit Grant No. 973302, Program Grant No. 179805, NHMRC project grant No. 157125, grants from the Australian Rotary Health Research Fund and the Australian Brewers Foundation. Copyright @ 2010 Bunce et al.Background: The association between brain white matter lesions and cognitive impairment in old age is well established.
However, little is known about this association in midlife. As this information will inform policy for early preventative
healthcare initiatives, we investigated non-periventricular frontal, temporal, parietal and occipital lobe white matter
hyperintensities (WMH) in relation to cognitive function in 428 (232 women) community-dwelling adults aged 44 to 48
years.
Results: Frontal white matter lesions were significantly associated with greater intraindividual RT variability in women, while temporal WMH were associated with face recognition deficits in men. Parietal and occipital lobe lesions were unrelated to
cognitive performance. These findings did not differ when education and a range of health variables, including vascular risk
factors, were taken into account.
Conclusion: Gender differences in WMH-cognition associations are discussed, and we conclude that small vessel disease is
present in midlife and has functional consequences which are generally not recognized. Preventative strategies should,
therefore, begin early in life.This article is available through the Brunel Open Access Publishing Fund
Charisma and Spirituality in the Early Church: A Study of Messalianism and Pseudo-Macarius
No full textThe thesis is an investigation into the concept of Charisma and Spirituality in the Early Church with particular emphasis upon the writings of Ps-Macarius, and of a group of ascetics known as the Messalians, evident in the late fourth / early fifth centuries. The Macarian writings are
examined to see what they reveal about the experiential pneumatic theology of the Early Church, the relationship between Syrian and Hellenic traditions of Christian Rhetoric, and the relationship between Ps-Macarius and the Cappadocian Circle. The Macarian corpus as a whole is examined to assess its rhetorical influences and style. The rhetoric of the Macarian corpus is seen to illustrate a high degree of sophistication. This study also gives definition to two terms that have become imprecise and diverse in their use: 'enkrateia' (self-control), and
`Syrian Christianity'. By isolating the characteristics of enkratefa the definitive stages of an encratic lifestyle are identified. The breaking down of the term into enkrateia, radical enkrateta and exclusive enkrateta enables a much clearer discussion to take place as to the
nature of the encratic theology of a group or individual. The final element of this study is a consideration of the distinct Macarian imagery that is evident within the corpus. Two images are considered in detail, the 'flight of the soul' and 'sober intoxication'. Overall this study
shows the variety of influences upon Ps-Macarius, and the uniqueness of his expression. The influences upon Ps-Macarius include a context of endemic Syrian spirituality, a radical encratic lifestyle, a Hellenic rhetorical training, and a distinct interpretation of Platonic and Neo-
Platonic images, coupled to the wider Judaic / Mesopotamian influences of his Church. It is shown that Ps-Macarius represents an individual voice that is distinct and recognisable amongst the Fathers of the Church
White-Light Generation with Sub-ps Pulses
No full textWe generate white light supercontinuum from slightly sub-picosecond pulses at 1.03 µm and 515 nm. We compare the spectra and stability for various crystals, focusing conditions and pulse durations, and determine the best parameters for sub-picosecond driver pulse duration. Comparing the experimental observations with the theory of white-light generation from Brodeur and Chin, it appears that in this particular range of pump pulse duration, two mechanisms interact and prevent a catastrophic collapse of the beam: multi-photon excitation (typical for ~100-fs-long pulses) and avalanche ionization (typical for >1-ps pulses). The two processes both manifest themselves in different experimental observations
Player agency in interactive narrative: audience, actor & author
No full textThe question motivating this review paper is, how can
computer-based interactive narrative be used as a constructivist learn-
ing activity? The paper proposes that player agency can be used to
link interactive narrative to learner agency in constructivist theory,
and to classify approaches to interactive narrative. The traditional
question driving research in interactive narrative is, ‘how can an in-
teractive narrative deal with a high degree of player agency, while
maintaining a coherent and well-formed narrative?’ This question
derives from an Aristotelian approach to interactive narrative that,
as the question shows, is inherently antagonistic to player agency.
Within this approach, player agency must be restricted and manip-
ulated to maintain the narrative. Two alternative approaches based
on Brecht’s Epic Theatre and Boal’s Theatre of the Oppressed are
reviewed. If a Boalian approach to interactive narrative is taken the
conflict between narrative and player agency dissolves. The question
that emerges from this approach is quite different from the traditional
question above, and presents a more useful approach to applying in-
teractive narrative as a constructivist learning activity
Synthesis, structure, and electronic properties of monomeric and dimeric trispyrazolylborate platinum(II) hydride complexes
No full textTp ' PtMe(H)(2) (2) [Tp ' = hydridotris(3,5-dimethylpyrazolyl)borate] has been prepared from Tp ' PtMe(CO) (1) via reaction with water in a basic acetone/water mixture. Protonation of 2 at one of the pyrazole nitrogen atoms induces methane elimination, and the resulting platinum(H) monohydride solvent intermediate (3) can be trapped by added ligand. Two chiral cationic platinum(II) monohydride complexes of the type [k(2)-((Hpz*)BHpz*(2),)Pt-(H)(L)][BAr ' (4)] [L = MeCN (4), CH2=CH2 (5); pz* = 3,5-dimethylpyrazolyl, BAr '4 = tetrakis(3,5-trifuoromethylphenyl)borate] have been isolated. If 2 is protonated in the absence of trapping ligand, a deep red hydride-bridged dinuclear complex, [k(2)-((Hpz*)BHpz*(2))Pt(Li-H)](2)[BAr ' (4)](2) (6), forms. DFT calculations supplement intuitive expectations regarding 3-center-2-electron bridging orbital descriptions for the electronic structure of this complex. X-ray structure determinations for the monomeric acetonitrile adduct 4 and the dicationic dimer 6 are reported
A region on chicken chromosome 2 affects both egg white thinning and egg weight
No full textAbstract We describe the results from genetic dissection of a QTL region on chicken chromosome 2, shown to affect egg weight and quality in an earlier genome scan of an F2 intercross between two divergent egg layer lines. As the 90% confidence intervals for the detected QTL covered tens of centiMorgans, new analyses were needed. The datasets were reanalysed with denser marker intervals to characterise the QTL region. Analysis of a candidate gene from the original QTL region, vimentin, did not support its role in controlling egg white thinning. Even after reanalysis with additional seven markers in the QTL area, the 90% confidence intervals remained large or even increased, suggesting the presence of multiple linked QTL for the traits. A grid search fitting two QTL on chromosome 2 for each trait suggested that there are two distinct QTL areas affecting egg white thinning in both production periods and egg weight in the late production period. The results indicate possible pleiotropic effects of some of the QTL on egg quality and egg weight. However, it was not possible to make a distinction between close linkage versus pleiotropic effects.</p
Emulsion experiment at the PS
No full textGuy Vanderhaege and Max Roberts (in white coat) near a pulsed magnet, inside the PS ring
The relationship between surface derivatization and the physical properties of bisarylphosphinidenetriironnonacarbonyl clusters
No full textA series of clusters, Fe-3(CO)(9)(mu(3)-P-p-C6H4X)(mu(3)-P-p-C6H4X') (X = X'= NMe2, OCH3, CH3, Cl, CF3, CN; X = CN, XI = NMe2) has been prepared using functionalized p-XC6H4PCl2 starting materials. The influence of changes in the X groups on the physical properties of the Fe-3(CO)(9) cluster core are examined. This cluster series displays two one-electron reductions to produce stable radical monoanions and diamagnetic dianions, allowing the behavior of all three species to be examined. Infrared, P-31 and H-1 NMR, and electron paramagnetic resonance (of the radical monoanion) spectroscopies as well as the structural characterization of two members of the series, Fe-3(CO)(9)(mu(3)-P-p-C6H4X)(mu(3)-P-p-C6H4X') (X = X' = NMe2; X = CN, X' = NMe2) by single crystal X-ray diffraction methods all indicate that the cluster structures are invariant with the nature of X. The Hammett linear free energy relationship is used to quantify the observed changes in cluster properties. Analysis of infrared, electron paramagnetic resonance and cyclic voltammetry data by the Hammett equation quantify the communication between the cluster surface and the Fe-3(CO)(9) core. Fenske-Hall molecular orbital calculations were used to assess the important orbital interactions between the substituted phenyl rings and the Fe-3(CO)(9) cluster core. (C) 1999 Elsevier Science S.A. All rights reserved
White matter damage and cognitive impairment after traumatic brain injury
No full textWhite matter disruption is an important determinant of cognitive impairment after brain injury, but conventional neuroimaging underestimates its extent. In contrast, diffusion tensor imaging provides a validated and sensitive way of identifying the impact of axonal injury. The relationship between cognitive impairment after traumatic brain injury and white matter damage is likely to
be complex. We applied a flexible technique—tract-based spatial statistics—to explore whether damage to specific white matter tracts is associated with particular patterns of cognitive impairment. The commonly affected domains of memory, executive function and information processing speed were investigated in 28 patients in the post-acute / chronic phase following traumatic brain injury and in 26 age-matched controls. Analysis of fractional anisotropy and diffusivity maps revealed widespread differences
in white matter integrity between the groups. Patients showed large areas of reduced fractional anisotropy, as well as increased mean and axial diffusivities, compared with controls, despite the small amounts of cortical and white matter damage visible on standard imaging. A stratified analysis based on the presence or absence of microbleeds (a marker of diffuse axonal injury) revealed diffusion tensor imaging to be more sensitive than gradient-echo imaging to white matter damage. The location of white matter abnormality predicted cognitive function to some extent. The structure of the fornices was correlated with associative learning and memory across both patient and control groups, whilst the structure of frontal lobe connections showed relationships with executive function that differed in the two groups. These results highlight the complexity of the relationships
between white matter structure and cognition. Although widespread and, sometimes, chronic abnormalities of white matter are identifiable following traumatic brain injury, the impact of these changes on cognitive function is likely to depend on damage to key pathways that link nodes in the distributed brain networks supporting high-level cognitive functions
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