Further evidence for linearly-dispersive Cooper pairs

A recent Bose-Einstein condensation (BEC) model of several cuprate superconductors is based on bosonic Cooper pairs (CPs) moving in 3D with a quadratic energy-momentum (dispersion) relation. The 3D BEC condensate-fraction vs. temperature (T/Tc, where Tc is the BEC transition temperature) formula poorly fits penetration-depth data for two cuprates in the range (1/2, 1]. We show how these fits are dramatically improved assuming cuprates to be quasi-2D, and how equally good fits obtain for conventional 3D and quasi-1D nanotube superconducting data, provided the correct CP dispersion is assumed in BEC at their assumed corresponding dimensionalities. This is offered as additional concrete empirical evidence for linearly-dispersive pairs in another recent BEC scenario of superconductors within which a BCS condensate turns out to be a very special case.Comment: 9 pages, 1 figur

System among the corticosteroids: specificity and molecular dynamics.

Fil: Brookes, Jennifer C.. University College London; Estados UnidosFil: Galigniana, Mario Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Harker, Anthony H.. University College London; Estados UnidosFil: Stoneham, A. Marshall. University College London; Estados UnidosFil: Vinson, Gavin P.. Queen Mary University of London; Reino Unid

Importance of quantum tunneling in vacancy-hydrogen complexes in diamond

Our ab initio calculations of the hyperfine parameters for negatively charged vacancy-hydrogen and nitrogen-vacancy-hydrogen complexes in diamond compare static defect models and models which account for the quantum tunneling behavior of hydrogen. The static models give rise to hyperfine splittings that are inconsistent with the experimental electron paramagnetic resonance data. In contrast, the hyperfine parameters for the quantum dynamical models are in agreement with the experimental observations. We show that the quantum motion of the proton is crucial to the prediction of symmetry and hyperfine constants for two simple defect centers in diamond. Static a priori methods fail for these systems

An evaluation of the adverse childhood experience trauma informed multi-agency early action together (ACE TIME) training: National roll out to police and partners

In a rapidly changing society, modern policing faces new pressures and increasing demands to respond to incidents of high threat, harm, risk and vulnerability. Responding to such incidents has become a core element of policing across the UK. Whilst the police are well placed to identify and respond to vulnerability, research has highlighted that traditional policing methods, training and systems are not designed to meet the changing levels and types of vulnerability demand. The National Police Chiefs’ Council (NPCC) and College of Policing (CoP) have highlighted the need to transform policing within the UK to develop a workforce of confident professionals with the skills to respond to vulnerability and the complex needs of the local community. The pan-Wales Early Action Together (E.A.T.) programme aimed to develop a whole systems response to vulnerability to enable police and multi-agency (MA) partners to recognise signs of vulnerability at the earliest opportunity and to work together to provide access to support beyond statutory services. Key to achieving this was the development and delivery of the Adverse Childhood Experience Trauma Informed Multi-agency Early Action Together (ACE TIME) training programme. The ACE TIME training aims to ensure that police and MA partners have the appropriate knowledge and skill to respond to vulnerability using an ACE and trauma-informed approach. The training built on a small-scale pilot carried out within South Wales police1 and was further developed by the ACE Coordinator Service positioned within Barnardo’s and the E.A.T. national programme team. Public Health Wales and Bangor University undertook an independent evaluation of the ACE TIME training to capture its immediate impact on police and MA partners’ knowledge, practice, competence and confidence when responding to vulnerability. The evaluation comprised a number of pre and post-training questionnaires that incorporated previously validated measures1 and a number of open-ended questions (see pg. 21) with open text boxes for participant’s comments. The current report evaluated the phase one roll out of the ACE TIME training (from September 2018 to January 2019). During the data collection period, 1,034 professionals were trained, of which 996 participated in the evaluation (849 police officers or staff and 147 MA partners). Police and MA partners across Wales from a range of different operational roles and teams took part in the evaluation (see table 3, pg. 24). Among police participants, approximately half worked in response roles (i.e., ‘999’ response; 51%). A further 21% worked within neighbourhood policing teams (NPT); and those from the public protection unit (PPU), custody, criminal investigation department (CID) and other investigative roles made up the remainder of departments (28%). Among MA partners, approximately 22% worked with children and young people’s education services; 22% within safeguarding, social care and family sector, 22% within the health and well-being sector and 16% in housing, community and local authority. The ACE TIME training is a core element of the E.A.T. programme, which sets out to provide police and partners across Wales with a universal understanding of vulnerability, and the knowledge and skills to confidently and competently respond to individuals who experience trauma. It supports the NPCC Policing Vision 20254 , which highlights the need for police to adopt professional curiosity to identify the potential indicators of vulnerability at the earliest opportunity and to reduce risk of harm through early intervention with partners. The training seeks to establish better multi-agency working practice, and support police to draw on wider services to deliver appropriate responses to vulnerability. The findings from the current evaluation suggest that, overall, the training had a positive impact on police and MA partners by increasing awareness of ACEs and related trauma, and the impact this may have on an individual throughout their lifetime; while also enabling staff to feel more competent and confident to respond in a trauma- and ACE-informed way. Furthermore, the findings suggest that the training significantly improved police attitudes towards a multi-agency ACE and trauma-informed approach to tackling vulnerability. Nonetheless, the findings also provide evidence of where there might be barriers to implementing the training into practice

Prospects for detecting the 21cm forest from the diffuse intergalactic medium with LOFAR

We discuss the feasibility of the detection of the 21cm forest in the diffuse IGM with the radio telescope LOFAR. The optical depth to the 21cm line has been derived using simulations of reionization which include detailed radiative transfer of ionizing photons. We find that the spectra from reionization models with similar total comoving hydrogen ionizing emissivity but different frequency distribution look remarkably similar. Thus, unless the reionization histories are very different from each other (e.g. a predominance of UV vs. x-ray heating) we do not expect to distinguish them by means of observations of the 21cm forest. Because the presence of a strong x-ray background would make the detection of 21cm line absorption impossible, the lack of absorption could be used as a probe of the presence/intensity of the x-ray background and the thermal history of the universe. Along a random line of sight LOFAR could detect a global suppression of the spectrum from z>12, when the IGM is still mostly neutral and cold, in contrast with the more well-defined, albeit broad, absorption features visible at lower redshift. Sharp, strong absorption features associated with rare, high density pockets of gas could be detected also at z~7 along preferential lines of sight.Comment: 12 pages, 13 figures. MNRAS, in pres

An isolated Dirac cone on the surface of ternary tetradymite-like topological insulators

We have extended the search for topological insulators to the ternary tetradymite-like compounds M2X2Y (M = Bi or Sb; X and Y = S, Se or Te), which are variations of the well-known binary compounds Bi2Se3 and Bi2Te3. Our first-principles computations suggest that five existing compounds are strong topological insulators with a single Dirac cone on the surface. In particular, stoichiometric Bi2Se2S, Sb2Te2Se and Sb2Te2S are predicted to have an isolated Dirac cone on their naturally cleaved surface. This finding paves the way for the realization of the topological transport regime.Comment: 4 pages, 3 figure

Structure-dependent exchange in the organic magnets Cu(II)Pc and Mn(II)Pc

We study exchange couplings in the organic magnets copper(II) phthalocyanine (Cu(II)Pc) and manganese(II) phthalocyanine (Mn(II)Pc) by a combination of Green's function perturbation theory and \textsl{ab initio} density-functional theory (DFT). Based on the indirect exchange model our perturbation-theory calculation of Cu(II)Pc qualitatively agrees with the experimental observations. DFT calculations performed on Cu(II)Pc dimer show a very good quantitative agreement with exchange couplings that we extract by using a global fitting for the magnetization measurements to a spin-1/2 Bonner-Fisher model. These two methods give us remarkably consistent trends for the exchange couplings in Cu(II)Pc when changing the stacking angles. The situation is more complex for Mn(II)Pc owing to the competition between super-exchange and indirect exchange.Comment: 13 pages,10 figures. To appear in Physical Review