3,015 research outputs found

    Quantum Entanglement in the Two Impurity Kondo Model

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    In order to quantify quantum entanglement in two impurity Kondo systems, we calculate the concurrence, negativity, and von Neumann entropy. The entanglement of the two Kondo impurities is shown to be determined by two competing many-body effects, the Kondo effect and the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, II. Due to the spin-rotational invariance of the ground state, the concurrence and negativity are uniquely determined by the spin-spin correlation between the impurities. It is found that there exists a critical minimum value of the antiferromagnetic correlation between the impurity spins which is necessary for entanglement of the two impurity spins. The critical value is discussed in relation with the unstable fixed point in the two impurity Kondo problem. Specifically, at the fixed point there is no entanglement between the impurity spins. Entanglement will only be created (and quantum information processing (QIP) be possible) if the RKKY interaction exchange energy, II, is at least several times larger than the Kondo temperature, TKT_K. Quantitative criteria for QIP are given in terms of the impurity spin-spin correlation.Comment: 7 pages, 3 figures, 1 tabl

    MicroRNA evolution by arm switching

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    MicroRNAs (miRNAs) modulate transcript stability and translation. Functional mature miRNAs are processed from one or both arms of the hairpin precursor. The miR-100/10 family has undergone three independent evolutionary events that have switched the arm from which the functional miRNA is processed. The dominant miR-10 sequences in the insects Drosophila melanogaster and Tribolium castaneum are processed from opposite arms. However, the duplex produced by Dicer cleavage has an identical sequence in fly and beetle. Expression of the Tribolium miR-10 sequence in Drosophila S2 cells recapitulates the native beetle pattern. Thus, arm usage is encoded in the primary miRNA sequence, but outside the mature miRNA duplex. We show that the predicted messenger RNA targets and inferred function of sequences from opposite arms differ significantly. Arm switching is likely to be general, and provides a fundamental mechanism to evolve the function of a miRNA locus and target gene network

    Let’s Take A Walk: Exploring the Impact of an Inclusive Walking Program on the Physical and Mental Health of Adults with Intellectual Disability

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    Background: People with intellectual disabilities experience health disparities and poorer health outcomes than people without disabilities. Increased physical activity has been found to reduce the impact of chronic health conditions among people with intellectual disabilities. Method: The current study explored the impact of an inclusive walking program on the physical and mental health of adults with intellectual disabilities. Let’s Take A Walk paired adults with intellectual disabilities, hereafter referred to as Community Walkers (n = 27), with college students to walk around a college campus twice a week for 45 minutes across 10 weeks. Data on mental health outcomes, specifically depression and anxiety, were collected from 24 Community Walkers across four-time points (pre-, mid-, post-, and 3-months following intervention), and data on physical health outcomes were collected across two-time points (pre- and post-intervention). Results: Community Walkers reported significant decreases in both depression and anxiety from pre to post-implementation. Particularly promising was clinically significant decreases in anxiety symptoms over the 10-week program. No differences were noted on Community Walkers’ measures of physical health. Conclusion: Inclusive walking programs are a valuable and promising mechanism for building social connections and inclusion and improving mental health for adults with intellectual disabilities

    Sustaining allied health telehealth services beyond the rapid response to COVID-19 : Learning from patient and staff experiences at a large quaternary hospital

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    The patient, clinician and administration staff perspectives of telehealth (specifically videoconferencing) services provided by Allied Health Professions (AHP) at a large quaternary hospital were explored. The purpose was to understand stakeholders’ perceptions of the service during initial COVID-19 restrictions and examine factors that influenced the implementation and sustained use of telehealth. A sequential mixed-methods approach was undertaken. Stage 1 involved surveys completed by patients (n = 109) and clinicians (n = 66) who received and provided care via telehealth, respectively, across six AHP departments. Stage 2 involved focus groups with clinicians (n = 24) and administrative staff (n = 13) to further examine implementation and sustainability factors. All participant groups confirmed that telehealth was a valid service model and valued the benefits it afforded, particularly during COVID-19 restrictions. Both patients and clinicians reported that not all AHP services could be delivered via telehealth and preferred a blended model of telehealth and in-person care. Increased administrative staff assistance was needed to support growing telehealth demand. Main factors to address are the need to expand AHP telehealth models and workforce/patient training, improve workflow processes and enhance technical support. Despite rapid implementation, telehealth experiences were overall positive. Study findings are being used to generate solutions to enhance and sustain AHP telehealth services

    Radioactive nuclei in the early Solar System: Analysis of the 15 isotopes produced by core-collapse supernovae

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    Short-lived radioactive isotopes (SLRs) with half-lives between 0.1 to 100 Myr can be used to probe the origin of the Solar System. In this work, we examine the core-collapse supernovae production of the 15 SLRs produced: 26Al, 36Cl, 41Ca, 53Mn, 60Fe, 92Nb, 97Tc, 98Tc, 107Pd, 126Sn, 129I, 135Cs, 146Sm, 182Hf, and 205Pb. We probe the impact of the uncertainties of the core-collapse explosion mechanism by examining a collection of 62 core-collapse models with initial masses of 15, 20, and 25 M⊙, explosion energies between 3.4 × 1050 and 1.8 × 1052 ergs and compact remnant masses between 1.5 M⊙ and 4.89 M⊙. We identify the impact of both explosion energy and remnant mass on the final yields of the SLRs. Isotopes produced within the innermost regions of the star, such as 92Nb and 97Tc, are the most affected by the remnant mass, 92Nb varying by five orders of magnitude. Isotopes synthesised primarily in explosive C-burning and explosive He-burning, such as 60Fe, are most affected by explosion energies. 60Fe increases by two orders of magnitude from the lowest to the highest explosion energy in the 15 M⊙ model. The final yield of each examined SLR is used to compare to literature models

    Pfam: clans, web tools and services

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    Pfam is a database of protein families that currently contains 7973 entries (release 18.0). A recent development in Pfam has enabled the grouping of related families into clans. Pfam clans are described in detail, together with the new associated web pages. Improvements to the range of Pfam web tools and the first set of Pfam web services that allow programmatic access to the database and associated tools are also presented. Pfam is available on the web in the UK (http://www.sanger.ac.uk/Software/Pfam/), the USA (http://pfam.wustl.edu/), France (http://pfam.jouy.inra.fr/) and Sweden (http://pfam.cgb.ki.se/)

    A central role for carbon-overflow pathways in the modulation of bacterial cell death.

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    Similar to developmental programs in eukaryotes, the death of a subpopulation of cells is thought to benefit bacterial biofilm development. However mechanisms that mediate a tight control over cell death are not clearly understood at the population level. Here we reveal that CidR dependent pyruvate oxidase (CidC) and α-acetolactate synthase/decarboxylase (AlsSD) overflow metabolic pathways, which are active during staphylococcal biofilm development, modulate cell death to achieve optimal biofilm biomass. Whereas acetate derived from CidC activity potentiates cell death in cells by a mechanism dependent on intracellular acidification and respiratory inhibition, AlsSD activity effectively counters CidC action by diverting carbon flux towards neutral rather than acidic byproducts and consuming intracellular protons in the process. Furthermore, the physiological features that accompany metabolic activation of cell death bears remarkable similarities to hallmarks of eukaryotic programmed cell death, including the generation of reactive oxygen species and DNA damage. Finally, we demonstrate that the metabolic modulation of cell death not only affects biofilm development but also biofilm-dependent disease outcomes. Given the ubiquity of such carbon overflow pathways in diverse bacterial species, we propose that the metabolic control of cell death may be a fundamental feature of prokaryotic development

    Measuring geometric phases of scattering states in nanoscale electronic devices

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    We show how a new quantum property, a geometric phase, associated with scattering states can be exhibited in nanoscale electronic devices. We propose an experiment to use interference to directly measure the effect of the new geometric phase. The setup involves a double path interferometer, adapted from that used to measure the phase evolution of electrons as they traverse a quantum dot (QD). Gate voltages on the QD could be varied cyclically and adiabatically, in a manner similar to that used to observe quantum adiabatic charge pumping. The interference due to the geometric phase results in oscillations in the current collected in the drain when a small bias across the device is applied. We illustrate the effect with examples of geometric phases resulting from both Abelian and non-Abelian gauge potentials.Comment: Six pages two figure
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