To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
SNP in the vitamin D receptor (VDR) gene is associated with risk of lower respiratory infections. The influence of genetic variation in the vitamin D pathway resulting in susceptibility to upper respiratory infections (URI) has not been investigated. We evaluated the influence of thirty-three SNP in eleven vitamin D pathway genes (DBP, DHCR7, RXRA, CYP2R1, CYP27B1, CYP24A1, CYP3A4, CYP27A1, LRP2, CUBN and VDR) resulting in URI risk in 725 adults in London, UK, using an additive model with adjustment for potential confounders and correction for multiple comparisons. Significant associations in this cohort were investigated in a validation cohort of 737 children in Manchester, UK. In all, three SNP in VDR (rs4334089, rs11568820 and rs7970314) and one SNP in CYP3A4 (rs2740574) were associated with risk of URI in the discovery cohort after adjusting for potential confounders and correcting for multiple comparisons (adjusted incidence rate ratio per additional minor allele ≥1·15, Pfor trend ≤0·030). This association was replicated for rs4334089 in the validation cohort (Pfor trend=0·048) but not for rs11568820, rs7970314 or rs2740574. Carriage of the minor allele of the rs4334089 SNP in VDR was associated with increased susceptibility to URI in children and adult cohorts in the United Kingdom.
Our understanding of the complex relationship between schizophrenia symptomatology and etiological factors can be improved by studying brain-based correlates of schizophrenia. Research showed that impairments in value processing and executive functioning, which have been associated with prefrontal brain areas [particularly the medial orbitofrontal cortex (MOFC)], are linked to negative symptoms. Here we tested the hypothesis that MOFC thickness is associated with negative symptom severity.
This study included 1985 individuals with schizophrenia from 17 research groups around the world contributing to the ENIGMA Schizophrenia Working Group. Cortical thickness values were obtained from T1-weighted structural brain scans using FreeSurfer. A meta-analysis across sites was conducted over effect sizes from a model predicting cortical thickness by negative symptom score (harmonized Scale for the Assessment of Negative Symptoms or Positive and Negative Syndrome Scale scores).
Meta-analytical results showed that left, but not right, MOFC thickness was significantly associated with negative symptom severity (βstd = −0.075; p = 0.019) after accounting for age, gender, and site. This effect remained significant (p = 0.036) in a model including overall illness severity. Covarying for duration of illness, age of onset, antipsychotic medication or handedness weakened the association of negative symptoms with left MOFC thickness. As part of a secondary analysis including 10 other prefrontal regions further associations in the left lateral orbitofrontal gyrus and pars opercularis emerged.
Using an unusually large cohort and a meta-analytical approach, our findings point towards a link between prefrontal thinning and negative symptom severity in schizophrenia. This finding provides further insight into the relationship between structural brain abnormalities and negative symptoms in schizophrenia.
This study is a subjective synthesis of the work of many academics, supervisors and practitioners on the topic of liquidity and many of its multiple aspects. It borrows heavily and freely from those works in the pursuit of coherence, as this subject can be both confused and confusing. Although many hypotheses, both established and speculative, are referred to, none is proposed in this paper. In order to be of possible use to a range of readers, it roams from the most basic and elementary to some of the most recent and advanced. In pursuit of brevity and readability, in many instances it can do little more than introduce a particular feature and leave further investigation to the reader. Liquidity is clearly a topic with much unfinished business. Our ambition in writing this paper is threefold: first, to raise awareness amongst actuaries of the wide-ranging implications for actuarial work of liquidity; second, to bring some coherence to the manifold measures and uses of the concept of liquidity by attempting to synthesise some of the key elements of knowledge today; finally, to highlight some of the more high profile and open questions relevant for actuarial work. This paper makes many references to behaviour during the crisis and its aftermath; however, it is not intended to be a forensic analysis of the crisis attributing causality. The crisis has simply served as an experiment during which many things became observable.
This paper gives a brief overview of the Gaia Research for European Astronomy Training (GREAT) network, including a description of the GREAT-ESF Research Network Programme and the GREAT Initial Training Network (GREAT-ITN). Scientific highlights from the GREAT-ITN are noted.
A novel phase modulator has been designed and analysed, assuming fabrication in a silicon-on-insulator material such as SIMOX. The proposed modulator is based upon a transverse p-i-n structure, utilising the plasma dispersion effect to produce the desired refractive index change in an optical rib waveguide. The device has been studied using the MEDICI two dimensional device simulation package to optimise the injected carrier interaction with the propagating optical mode. Whilst the device is designed to support a single optical mode, it measures several micrometers in cross sectional dimensions, thereby simplifying fabrication and allowing efficient coupling to other single mode devices such as optical fibers. Furthermore the device has an extremely high figure of merit, predicting over 200 degrees of induced phase shift per volt per mm. This implies a short active length together with a low power requirement.
Microstructural evolution in thin-film strips is of interest due to the direct effect of grain structure on integrated circuit interconnect reliability and resistance to electromigration-induced failure. We have explored the evolution of interconnect grain structure via a two-dimensional grain growth simulation. We focus on the strip's transformation to the bamboo structure, in which individual grains traverse the width of the strip. We find that the approach to a fully bamboo structure is exponential, and that the rate of transformation is inversely proportional to the square of the strip width. When the simulation is extended to model grain boundary pinning due to grooving at grain boundary – free surface intersections, we find that there exists a maximum strip width to thickness ratio beyond which the transformation to the bamboo structure does not proceed to completion. By using our simulation results in conjunction with a “failure unit” model for electromigration-induced failure  we are able to reproduce the experimentally observed abrupt increase in time-to-failure below a critical strip width, and also model the reliability as a function of annealing conditions.
We report on the use of lithium ion (Li+) drifting1 as a sensitive means to study Si self-interstitial (SiI) diffusion.2 Li+ properties in silicon are well known from extensive ion drift studies and Li+ interactions with dopants and point defects.3 We have used this low temperature (∼100°C) technique in combination with Si1 injection from oxides to delineate, identify and eliminate D defects4 in certain p-type floating zone (FZ) Si single crystals.5 Our results suggest Si1 diffusion occurs to a depth of at least 10 mm into the bulk during phosphorus (P) diffusion with oxidation (i.e., POCI3 process) at 950°C for 100 min. Process modeling of this lower bound SiI diffusion using SUPREM-IV9 results in a Sii diffusivity of 3.5×10−6 cm2/s at 950°C.
We present out-diffusion of Zn in Si as a new method to study properties of Si vacancies. Out-diffusion experiments were performed on homogeneously Zn-doped Si samples at 1107°C and 1154°C. The resulting concentration-depth profiles were measured by means of spreading-resistance profiling. Based on a diffusion model in which Zn migrates simultaneously via the kick-out and the dissociative mechanism all experimental profiles were modeled by computer simulations. The calculations reveal that out-diffusion of Zn from Si occurs to a considerable extent via the dissociative mechanism. Hence, vacancy properties like the equilibrium concentration CVeq and the transport capacity CveqDV can be extracted from profile fittings. The results are compared with literature data deduced from in-diffusion experiments.
The process-induced stress in interconnects within integrated circuits (IC) has a direct influence on the mean time to failure of the devices. Since measurement of stress in individual metallised lines is not possible by existing techniques, another approach has been adopted where a test structure is generated during fabrication based on a micro-rotating cantilever sensor. To support the design, finite element modeling (FEM) has been performed. By comparing the rotation predicted by FEM simulations and that observed experimentally, a clear discrepancy is observed which is critically dependent on the details of the sensor design, the pattern transfer of the lithographic process and on the dry etching processing.
We use Virtual Observatory methods to investigate the association between radio and X-ray emission at high redshifts. Fifty-five of the 92 HDF(N) sources resolved by combining MERLIN+VLA data were detected by Chandra, of which 18 are hard enough and bright enough to be obscured AGN. The high-z population of μJy radio sources is dominated by starbursts an order of magnitude more active and more extended than any found at z < 1 and at least a quarter of these simultaneously host highly X-ray-luminous obscured AGN.
The risks posed by a range of acoustic scientific instruments were assessed by the construction of matrices of scale and likelihood. We recognized six levels of impact ranging from none or short term, minimal behavioural response (Level 1) to multiple injuries and fatalities and/or compromised populations (Level 6) and six levels of likelihood ranging from “Expected in almost all instances” (Level 1) to “cannot see how it could happen” (Level 6). Typical scientific instruments ranging from acoustic releases to large air gun arrays were assessed. To provide a perspective for the risks of scientific operations, other activities were also ranked. These included large chemical explosions, submarine detection sonars implicated in some mass strandings of cetaceans and normal Antarctic shipping activities. The conclusion reached was that most scientific instruments pose a similar or lower risk than normal shipping operations. High source-level equipment poses some risk to individual animals' hearing and so should be mitigated. Likewise, survey planning should be designed to avoid trapping animals in narrow, constricted sea ways. Long term, cumulative impacts are still difficult to detect in areas with greater anthropogenic noise than the Antarctic but we concluded that any possible long term impacts should be mitigated by maintaining the low levels of activity using high source-level equipment through data sharing and survey planning.
N2 fixation, measured as acetylene reduction, was studied in laboratory cultures and in natural assemblages (both
as a mixed population and as individually picked colonies) of the heterocystous cyanobacteria Aphanizomenon sp.
and Nodularia spp. from the Baltic Sea. During a diurnal cycle of alternating light and darkness, these organisms
reduced acetylene predominantly during the period of illumination, although considerable activity was also
observed during the dark period. In both laboratory cultures and natural populations N2 fixation was saturated
below a photon flux density of 600 μm−2 s−1. In cyanobacterial blooms in the Baltic Sea, nitrogenase activity was
mostly confined to the surface layers. Samples collected from greater depths did not possess the same capacity for
acetylene reduction as samples from the surface itself, even when incubated at the photon flux density prevailing
in surface waters. This suggests that, with respect to N2 fixation, Baltic cyanobacteria are adapted to the intensity
of illumination that they are currently experiencing.