5,273 research outputs found
The envirome and the connectome: exploring the structural noise in the human brain associated with socioeconomic deprivation
Complex cognitive functions are widely recognized to be the result of a number of brain regions working together as large-scale networks. Recently, complex network analysis has been used to characterize various structural properties of the large scale network organization of the brain. For example, the human brain has been found to have a modular architecture i.e. regions within the network form communities (modules) with more connections between regions within the community compared to regions outside it. The aim of this study was to examine the modular and overlapping modular architecture of the brain networks using complex network analysis. We also examined the association between neighborhood level deprivation and brain network structure â modularity and grey nodes. We compared network structure derived from anatomical MRI scans of 42 middle-aged neurologically healthy men from the least (LD) and the most deprived (MD) neighborhoods of Glasgow with their corresponding random networks. Cortical morphological covariance networks were constructed from the cortical thickness derived from the MRI scans of the brain. For a given modularity threshold, networks derived from the MD group showed similar number of modules compared to their corresponding random networks, while networks derived from the LD group had more modules compared to their corresponding random networks. The MD group also had fewer grey nodes â a measure of overlapping modular structure. These results suggest that apparent structural difference in brain networks may be driven by differences in cortical thicknesses between groups. This demonstrates a structural organization that is consistent with a system that is less robust and less efficient in information processing. These findings provide some evidence of the relationship between socioeconomic deprivation and brain network topology
Low loss Ge-on-Si waveguides operating in the 8â14 ”m atmospheric transmission window
Germanium-on-silicon waveguides were modeled, fabricated and characterized at wavelengths ranging from 7.5 to 11 ”m. Measured waveguide losses are below 5 dB/cm for both TE and TM polarization and reach values of ⌠1 dB/cm for ℠10 ”m wavelengths for the TE polarization. This work demonstrates experimentally for the first time that Ge-on-Si is a viable waveguide platform for sensing in the molecular fingerprint spectral region. Detailed modeling and analysis is presented to identify the various loss contributions, showing that with practical techniques losses below 1 dB/cm could be achieved across the full measurement range
The effect of transmucosal 0.2mg/kg Midazolam premedication on dental anxiety, anaesthetic induction and psychological morbidity in children undergoing general anaesthesia for tooth extraction
<b>Background:</b> The project aims were to evaluate the benefit of transmucosal Midazolam 0.2mg/kg pre-medication on anxiety, induction behaviour and psychological morbidity in children undergoing general anaesthesia (GA) extractions. <b>Method:</b> 179 children aged 5-10 years (mean 6.53 years) participated in this randomised, double blind, placebo controlled trial. Ninety children had Midazolam placed in the buccal pouch. Dental anxiety was recorded pre operatively and 48 hours later using a child reported MCDAS-FIS scale. Behaviour at anaesthetic induction was recorded and psychological morbidity was scored by the parent using the Rutter Scale pre-operatively and again one-week later. Subsequent dental attendance was recorded at one, three and six months after GA. <b>Results:</b> Whilst levels of mental anxiety did not reduce overall, the most anxious patients demonstrated a reduction in anxiety after receiving midazolam premedicationmay (p=0.01). Neither induction behaviour nor psychological morbidity improved. Irrespective of group, parents reported less hyperactive (p= 0.002) and more prosocial behaviour (p=0.002) after the procedure:;, older children improved most (p=0.048), Post GA Dental attendance was poor and unrelated to after the procedure and unaffected by premedication. <b>Conclusion:</b> 0.2mg/kg buccal Midazolam provided some evidence for reducing anxiety in the most dentally anxious patients. However, induction behaviour, psychological morbidity and subsequent dental attendance were not found to alter between the premedication groups
Beam interactions in one-dimensional saturable waveguide arrays
The interaction between two parallel beams in one-dimensional discrete
saturable systems has been investigated using lithium niobate nonlinear
waveguide arrays. When the beams are separated by one channel and in-phase it
is possible to observe soliton fusion at low power levels. This new result is
confirmed numerically. By increasing the power, soliton-like propagation of
weakly-coupled beams occurs. When the beams are out-of-phase the most
interesting result is the existence of oscillations which resemble the recently
discovered Tamm oscillations.Comment: 5 pages, 6 figures, submitted to Phys. Rev.
Optical properties of highly n-doped germanium obtained by in situ doping and laser annealing
High n-type doping in germanium is essential for many electronic and optoelectronic applications especially for high performance Ohmic contacts, lasing and mid-infrared plasmonics. We report on the combination of in situ doping and excimer laser annealing to improve the activation of phosphorous in germanium. An activated n-doping concentration of 8.8ââĂââ1019 cmâ3 has been achieved starting from an incorporated phosphorous concentration of 1.1ââĂââ1020 cmâ3. Infrared reflectivity data fitted with a multi-layer Drude model indicate good uniformity over a 350ânm thick layer. Photoluminescence demonstrates clear bandgap narrowing and an increased ratio of direct to indirect bandgap emission confirming the high doping densities achieved
D3 Brane Action and Fermion Zero Modes in Presence of Background Flux
We derive the fermion bilinear terms in the world volume action for a D3
brane in the presence of background flux. In six-dimensional compactifications
non-perturbative corrections to the superpotential can arise from an Euclidean
D3-brane instanton wrapping a divisor in the internal space. The bilinear terms
give rise to fermion masses and are important in determining these corrections.
We find that the three-form flux generically breaks a U(1) subgroup of the
structure group of the normal bundle of the divisor. In an example of
compactification on T^6/Z_2, six of the sixteen zero modes originally present
are lifted by the flux.Comment: Important factor of ``i'' was overlooked in Euclidean continuation of
WZ term. This changes the count of zero-modes in the T^6/Z_2 example. Main
result stays unchanged. We thank Bergshoeff, Kallosh, Kashani-Poor, Sorokin
and Tomasiello for pointing this ou
Atomic Diagnostics of X-ray Irradiated Protoplanetary Disks
We study atomic line diagnostics of the inner regions of protoplanetary disks
with our model of X-ray irradiated disk atmospheres which was previously used
to predict observable levels of the NeII and NeIII fine-structure transitions
at 12.81 and 15.55mum. We extend the X-ray ionization theory to sulfur and
calculate the fraction of sulfur in S, S+, S2+ and sulfur molecules. For the
D'Alessio generic T Tauri star disk, we find that the SI fine-structure line at
25.55mum is below the detection level of the Spitzer Infrared Spectrometer
(IRS), in large part due to X-ray ionization of atomic S at the top of the
atmosphere and to its incorporation into molecules close to the mid-plane. We
predict that observable fluxes of the SII 6718/6732AA forbidden transitions are
produced in the upper atmosphere at somewhat shallower depths and smaller radii
than the neon fine-structure lines. This and other forbidden line transitions,
such as the OI 6300/6363AA and the CI 9826/9852AA lines, serve as complementary
diagnostics of X-ray irradiated disk atmospheres. We have also analyzed the
potential role of the low-excitation fine-structure lines of CI, CII, and OI,
which should be observable by SOFIA and Herschel.Comment: Accepted by Ap
Radio-Continuum study of the Nearby Sculptor Group Galaxies. Part 1: NGC 300 at lambda = 20 cm
A series of new radio-continuum (lambda=20 cm) mosaic images focused on the
NGC 300 galactic system were produced using archived observational data from
the VLA and/or ATCA. These new images are both very sensitive (rms=60 microJy)
and feature high angular resolution (<10"). The most prominent new feature is
the galaxy's extended radio-continuum emission, which does not match its
optical appearance. Using these newly created images a number of previously
unidentified discrete sources have been discovered. Furthermore, we demonstrate
that a joint deconvolution approach to imaging this complete data-set is
inferior when compared to an immerge approach.Comment: 13 pages, 12 figures, accepted to APSS, new version to correct the
missing reference
Eclogites and basement terrane tectonics in the northern arm of the Grenville orogen, NW Scotland
The presence of eclogites within continental crust is a key indicator of collisional orogenesis. Eclogites within the Eastern Glenelg basement inlier of the Northern Highland Terrane (NHT) have been re-dated in order to provide more accurate constraints on the timing of collision within the northern arm of the Grenville Orogen. The eclog-ites yield dates of ca.1200 Ma which are interpreted to record the onset of continent-continent interaction, and the NHT as a whole is thought to represent the lower plate in successive 1200-1000 Ma collision events. The Eastern Glenelg basement inlier is viewed as a fragment of the leading edge of the NHT continental basement that was partially subducted along a suture and then exhumed back up the subduction channel. Differences in ages of igneous protoliths and intrusive histories, and metamorphic events (this paper) between the NHT basement and the Laurentian foreland, suggests that they were separate crustal blocks until after ca. 1600 Ma. We therefore suggest that: (1) the NHT represents a fragment of Archean-Paleoproterozoic crust that was reworked within the ca. 1.7-1.6 Ga Labradorian-Gothian belt, although whether it was derived from Laurentia or Baltica is uncertain, and (2) amalgamation of the NHT with the Laurentian foreland did not occur until the terminal stages of the Grenville collision at ca. 1000 Ma
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