Using a recent time-of-flight measurement technique with 1 ps time resolution and electron-energy spectroscopy, we develop a method to measure the longitudinal-optical-phonon emission rate of hot ...electrons traveling along a depleted edge of a quantum Hall bar. Comparison to a single-particle model implies the scattering mechanism involves a two-step process via an intra-Landau-level transition. We show that this can be suppressed by control of the edge potential profile, and a scattering length >1 mm can be achieved, allowing the use of this system for scalable single-electron device applications.
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Animal models of schizophrenia Jones, CA; Watson, DJG; Fone, KCF
British journal of pharmacology,
October 2011, 2011-Oct, 2011-10-00, 20111001, Volume:
164, Issue:
4
Journal Article
Peer reviewed
Open access
Developing reliable, predictive animal models for complex psychiatric disorders, such as schizophrenia, is essential to increase our understanding of the neurobiological basis of the disorder and for ...the development of novel drugs with improved therapeutic efficacy. All available animal models of schizophrenia fit into four different induction categories: developmental, drug‐induced, lesion or genetic manipulation, and the best characterized examples of each type are reviewed herein. Most rodent models have behavioural phenotype changes that resemble ‘positive‐like’ symptoms of schizophrenia, probably reflecting altered mesolimbic dopamine function, but fewer models also show altered social interaction, and learning and memory impairment, analogous to negative and cognitive symptoms of schizophrenia respectively. The negative and cognitive impairments in schizophrenia are resistant to treatment with current antipsychotics, even after remission of the psychosis, which limits their therapeutic efficacy. The MATRICS initiative developed a consensus on the core cognitive deficits of schizophrenic patients, and recommended a standardized test battery to evaluate them. More recently, work has begun to identify specific rodent behavioural tasks with translational relevance to specific cognitive domains affected in schizophrenia, and where available this review focuses on reporting the effect of current and potential antipsychotics on these tasks. The review also highlights the need to develop more comprehensive animal models that more adequately replicate deficits in negative and cognitive symptoms. Increasing information on the neurochemical and structural CNS changes accompanying each model will also help assess treatments that prevent the development of schizophrenia rather than treating the symptoms, another pivotal change required to enable new more effective therapeutic strategies to be developed.
LINKED ARTICLES This article is part of a themed issue on Translational Neuropharmacology. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2011.164.issue‐4
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ABSTRACT
Our understanding of planetary systems different to our own has grown dramatically in the past 30 yr. However, our efforts to ascertain the degree to which the Solar system is abnormal or ...unique have been hindered by the observational biases inherent to the methods that have yielded the greatest exoplanet hauls. On the basis of such surveys, one might consider our planetary system highly unusual – but the reality is that we are only now beginning to uncover the true picture. In this work, we use the full 18-yr archive of data from the Anglo-Australian Planet Search to examine the abundance of ‘cool Jupiters’ – analogues to the Solar system’s giant planets, Jupiter and Saturn. We find that such planets are intrinsically far more common through the cosmos than their siblings, the hot Jupiters. We find that the occurrence rate of such ‘cool Jupiters’ is $6.73^{+2.09}_{-1.13}$ per cent, almost an order of magnitude higher than the occurrence of hot Jupiters (at $0.84^{+0.70}_{-0.20}$ per cent). We also find that the occurrence rate of giant planets is essentially constant beyond orbital distances of ∼1 au. Our results reinforce the importance of legacy radial velocity surveys for the understanding of the Solar system’s place in the cosmos.
We use a microwave field to control the quantum state of optical photons stored in a cold atomic cloud. The photons are stored in highly excited collective states (Rydberg polaritons) enabling both ...fast qubit rotations and control of photon-photon interactions. Through the collective read-out of these pseudospin rotations it is shown that the microwave field modifies the long-range interactions between polaritons. This technique provides a powerful interface between the microwave and optical domains, with applications in quantum simulations of spin liquids, quantum metrology and quantum networks.
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The geological units on the floor of Jezero crater, Mars, are part of a wider regional stratigraphy of olivine-rich rocks, which extends well beyond the crater. We investigate the petrology of ...olivine and carbonate-bearing rocks of the Séítah formation in the floor of Jezero. Using multispectral images and x-ray fluorescence data, acquired by the Perseverance rover, we performed a petrographic analysis of the Bastide and Brac outcrops within this unit. We find that these outcrops are composed of igneous rock, moderately altered by aqueous fluid. The igneous rocks are mainly made of coarse-grained olivine, similar to some Martian meteorites. We interpret them as an olivine cumulate, formed by settling and enrichment of olivine through multi-stage cooling of a thick magma body.
The discovery of a very cool binary system Burningham, Ben; Leggett, S. K.; Lucas, P. W. ...
Monthly Notices of the Royal Astronomical Society,
June 2010, Volume:
404, Issue:
4
Journal Article
Peer reviewed
Open access
We report the discovery of a very cool d/sdL7+T7.5p common proper motion binary system, SDSS J1416+13AB, found by cross-matching the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey ...(UKIDSS) Large Area Survey Data Release 5 (UKIDSS LAS DR4) against the Sloan Digital Sky Survey Data Release 7. The d/sdL7 is blue in J−H and H−K and has other features suggestive of low metallicity and/or high gravity. The T7.5p displays spectral peculiarity seen before in earlier type dwarfs discovered in UKIDSS LAS DR4, and referred to as CH4-J-early peculiarity, where the CH4-J index, based on the absorption to the red side of the J-band peak, suggests an earlier spectral type than the H2O-J index, based on the blue side of the J-band peak, by ∼2 subtypes. We suggest that CH4-J-early peculiarity arises from low metallicity and/or high gravity, and speculate as to its use for classifying T dwarfs. UKIDSS and follow-up United Kingdom Infrared Telescope/Wide Field CAMera (UKIRT/WFCAM) photometry shows the T dwarf to have the bluest near-infrared colours yet seen for such an object with H−K=−1.31 ± 0.17. Warm Spitzer IRAC photometry shows the T dwarf to have extremely red H−4.5= 4.86 ± 0.04, which is the reddest yet seen for a substellar object. The lack of parallax measurement for the pair limits our ability to estimate parameters for the system. However, applying a conservative distance estimate of 5–15 pc suggests a projected separation in range 45–135 au. By comparing H−K:H−4.5 colours of the T dwarf to spectral models, we estimate that Teff= 500 K and M/H∼− 0.30, with log g∼ 5.0. This suggests a mass of ∼30 MJupiter for the T dwarf and an age of ∼10 Gyr for the system. The primary would then be a 75 MJupiter object with log g∼ 5.5 and a relatively dust-free Teff∼ 1500 K atmosphere. Given the unusual properties of the system we caution that these estimates are uncertain. We eagerly await parallax measurements and high-resolution imaging which will constrain the parameters further.
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The concept of 'steering' was introduced in 1935 by Schrödinger as a generalization of the EPR (Einstein-Podolsky-Rosen) paradox. It has recently been formalized as a quantum-information task with ...arbitrary bipartite states and measurements, for which the existence of entanglement is necessary but not sufficient. Previous experiments in this area have been restricted to an approach that followed the original EPR argument in considering only two different measurement settings per side. Here we demonstrate experimentally that EPR-steering occurs for mixed entangled states that are Bell local (that is, that cannot possibly demonstrate Bell non-locality). Unlike the case of Bell inequalities, increasing the number of measurement settings beyond two-we use up to six-significantly increases the robustness of the EPR-steering phenomenon to noise.
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We analyze dispersion measure (DM) variations of 37 millisecond pulsars in the nine-year North American Nanohertz Observatory for Gravitational Waves (NANOGrav) data release and constrain the sources ...of these variations. DM variations can result from a changing distance between Earth and the pulsar, inhomogeneities in the interstellar medium, and solar effects. Variations are significant for nearly all pulsars, with characteristic timescales comparable to or even shorter than the average spacing between observations. Five pulsars have periodic annual variations, 14 pulsars have monotonically increasing or decreasing trends, and 14 pulsars show both effects. Of the four pulsars with linear trends that have line-of-sight velocity measurements, three are consistent with a changing distance and require an overdensity of free electrons local to the pulsar. Several pulsars show correlations between DM excesses and lines of sight that pass close to the Sun. Mapping of the DM variations as a function of the pulsar trajectory can identify localized interstellar medium features and, in one case, an upper limit to the size of the dispersing region of 4 au. Four pulsars show roughly Kolmogorov structure functions (SFs), and another four show SFs less steep than Kolmogorov. One pulsar has too large an uncertainty to allow comparisons. We discuss explanations for apparent departures from a Kolmogorov-like spectrum, and we show that the presence of other trends and localized features or gradients in the interstellar medium is the most likely cause.
Abstract Background A series of models have been developed to identify patients at high risk for poor outcomes after transcatheter aortic valve replacement (TAVR) to help guide treatment choices, ...offer patients realistic expectations of long-term outcomes, and support decision making. Objectives This study examined the performance of the previously developed TAVR Poor Outcome risk models in an external dataset and explored the incremental contribution of geriatric domains to model performance. Methods Poor outcome after TAVR was defined as death, poor quality of life (QOL), or decline in QOL, as assessed using the Kansas City Cardiomyopathy Questionnaire. We tested 4 TAVR Poor Outcome risk models: 6-month and 1-year full and clinical (reduced) models. We examined each model’s discrimination and calibration in the CoreValve trial dataset, and then tested the incremental contribution of frailty and disability markers to the model’s discrimination using the incremental discrimination index. Results Among 2,830 patients who underwent TAVR in the CoreValve US Pivotal Extreme and High Risk trials and associated continued access registries, 31.2% experienced a poor outcome at 6 months following TAVR (death, 17.6%; very poor QOL, 11.6%; QOL decline, 2.0%) and 50.8% experienced a poor outcome at 1 year (death, 30.2%; poor QOL, 19.6%; QOL, decline 1.0%). The models demonstrated similar discrimination as in the Placement of Aortic Transcatheter Valves Trial cohorts (c-indexes, 0.637 to 0.665) and excellent calibration. Adding frailty as a syndrome increased the c-indexes by 0.000 to 0.004 (incremental discrimination index, p < 0.01 for all except the 1-year clinical model), with the most important individual components being disability and unintentional weight loss. Conclusions Although discrimination of the TAVR Poor Outcome risk models was generally moderate, calibration was excellent among patients with different risk profiles and treated with a different TAVR device. These findings demonstrated the value of these models for individualizing outcome predictions in high-risk patients undergoing TAVR.
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Environmental Enteric Dysfunction: An Overview Crane, Rosie J.; Jones, Kelsey D. J.; Berkley, James A.
Food and nutrition bulletin,
03/2015, Volume:
36, Issue:
1_suppl1
Journal Article
Peer reviewed
Open access
Background
Environmental enteric dysfunction (EED) refers to an incompletely defined syndrome of inflammation, reduced absorptive capacity, and reduced barrier function in the small intestine. It is ...widespread among children and adults in low- and middle-income countries. Understanding of EED and its possible consequences for health is currently limited.
Objective
A narrative review of the current understanding of EED: epidemiology, pathogenesis, therapies, and relevance to child health.
Methods
Searches for key papers and ongoing trials were conducted using PUBMED 1966–June 2014; ClinicalTrials. gov; the WHO Clinical Trials Registry; the Cochrane Library; hand searches of the references of retrieved literature; discussions with experts; and personal experience from the field.
Results
EED is established during infancy and is associated with poor sanitation, certain gut infections, and micronutrient deficiencies. Helicobacter pylori infection, small intestinal bacterial overgrowth (SIBO), abnormal gut microbiota, undernutrition, and toxins may all play a role. EED is usually asymptomatic, but it is important due to its association with stunting. Diagnosis is frequently by the dual sugar absorption test, although other biomarkers are emerging. EED may partly explain the reduced efficacy of oral vaccines in low- and middle-income countries and the increased risk of serious infection seen in children with undernutrition.
Conclusions
Despite its potentially significant impacts, it is currently unclear exactly what causes EED and how it can be treated or prevented. Ongoing trials involve nutritional supplements, water and sanitation interventions, and immunomodulators. Further research is needed to better understand this condition, which is of likely crucial importance for child health and development in low- and middle-income settings.
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