2,011 research outputs found
Enhanced spin triplet superconductivity due to Kondo destabilization
In a Kondo lattice system, suppression of effective Kondo coupling leads to
the breakdown of the heavy-electron metal and a change in the electronic
structure. Spin triplet superconductivity in the Kondo lattice UTe2 appears to
be associated with spin fluctuations originating from incipient ferromagnetic
order. Here we show clear evidence of twofold enhancement of spin-triplet
superconductivity near the pressure-driven suppression of the Kondo coherence,
implying that superconductivity is strengthened by the affiliated growth of
both spin and charge fluctuations. The coherent Kondo state discontinuously
transitions to ferromagnetic order at higher pressures. Application of magnetic
field tunes the system back across a first-order phase boundary. Straddling
this phase boundary, we find another example of reentrant superconductivity in
UTe2. In addition to spin fluctuations associated with ferromagnetism, our
results show that a Kondo-driven Fermi surface instability may be playing a
role in stabilizing spin triplet superconductivity
Enhancement and Reentrance of Spin Triplet Superconductivity in UTe₂ under Pressure
Spin triplet superconductivity in the Kondo lattice UTe2 appears to be associated with spin fluctuations originating from incipient ferromagnetic order. Here we show clear evidence of twofold enhancement of superconductivity under pressure, which discontinuously transitions to magnetic order, likely of ferromagnetic nature, at higher pressures. The application of a magnetic field tunes the system back across a first-order phase boundary. Straddling this phase boundary, we find another example of reentrant superconductivity in UTe2. As the superconductivity and magnetism exist on two opposite sides of the first-order phase boundary, our results indicate other microscopic mechanisms may be playing a role in stabilizing spin triplet superconductivity in addition to spin fluctuations associated with magnetism
Single-Component Superconductivity in UTe at Ambient Pressure
The microscopic mechanism of Cooper pairing in a superconductor leaves its
fingerprint on the symmetry of the order parameter. UTe has been inferred
to have a multi-component order parameter that entails exotic effects like time
reversal symmetry breaking. However, recent experimental observations in
newer-generation samples have raised questions about this interpretation,
pointing to the need for a direct experimental probe of the order parameter
symmetry. Here, we use pulse echo ultrasound to measure the elastic moduli of
samples of UTe that exhibit both one and two superconducting transitions.
We demonstrate the absence of thermodynamic discontinuities in the shear
elastic moduli of both single- and double-transition samples, providing direct
evidence that UTe has a single-component superconducting order parameter.
We further show that the superconductivity is highly sensitive to compression
strain along the and axes, but insensitive to strain along the
axis. This leads us to suggest a single-component, odd-parity order
parameterspecifically the B order parameteras the most likely
order parameter in UTe.Comment: 19 pages, 11 figures, 5 table
Evaluation of the Tsima community mobilization intervention to improve engagement in HIV testing and care in South Africa: study protocol for a cluster randomized trial
Abstract Background HIV transmission can be decreased substantially by reducing the burden of undiagnosed HIV infection and expanding early and consistent use of antiretroviral therapy (ART). Treatment as prevention (TasP) has been proposed as key to ending the HIV epidemic. To activate TasP in high prevalence countries, like South Africa, communities must be motivated to know their status, engage in care, and remain in care. Community mobilization (CM) has the potential to significantly increase uptake testing, linkage to and retention in care by addressing the primary social barriers to engagement with HIV care—including poor understanding of HIV care; fear and stigma associated with infection, clinic attendance and disclosure; lack of social support; and gender norms that deter men from accessing care. Methods/design Using a cluster randomized trial design, we are implementing a 3-year-theory-based CM intervention and comparing gains in HIV testing, linkage, and retention in care among individuals residing in 8 intervention communities to that of individuals residing in 7 control communities. Eligible communities include 15 villages within a health and demographic surveillance site (HDSS) in rural Mpumalanga, South Africa, that were not exposed to previous CM efforts. CM activities conducted in the 8 intervention villages map onto six mobilization domains that comprise the key components for community mobilization around HIV prevention. To evaluate the intervention, we will link a clinic-based electronic clinical tracking system in all area clinics to the HDSS longitudinal census data, thus creating an open, population-based cohort with over 30,000 18–49-year-old residents. We will estimate the marginal effect of the intervention on individual outcomes using generalized estimating equations. In addition, we will evaluate CM processes by conducting baseline and endline surveys among a random sample of 1200 community residents at each time point to monitor intervention exposure and community level change using validated measures of CM. Discussion Given the known importance of community social factors with regard to uptake of testing and HIV care, and the lack of rigorously evaluated community-level interventions effective in improving testing uptake, linkage and retention, the proposed study will yield much needed data to understand the potential of CM to improve the prevention and care cascade. Further, our work in developing a CM framework and domain measures will permit validation of a CM conceptual framework and process, which should prove valuable for community programming in Africa. Trial Registration NCT02197793 Registered July 21, 2014
Astonish Me! Recalling the Cabaret Spirit
Program for the 1999 RISD Wintersessoin Cabaret intiated by the Image and Word class in collaboration with students of RISD Cabaret 1998 and held at AS220. The presentation was conceived and performed in homage and celebration of past RISD Cabaret shows 1987-1998. Graphic Design: Ron Winter, Ji-Ho Sohn and Eric Urban.https://digitalcommons.risd.edu/liberalarts_cabaret_programs/1010/thumbnail.jp
Disseminated and Congenital Toxoplasmosis in a Mother and Child With Activated PI3-Kinase δ Syndrome Type 2 (APDS2): Case Report and a Literature Review of Toxoplasma Infections in Primary Immunodeficiencies
Phosphoinositide 3-kinase (PI3K) plays an integral role in lymphocyte function. Mutations in PIK3CD and PIK3R1, encoding the PI3K p110δ and p85α subunits, respectively, cause increased PI3K activity and result in immunodeficiency with immune dysregulation. We describe here the first cases of disseminated and congenital toxoplasmosis in a mother and child who share a pathogenic mutation in PIK3R1 and review the mechanisms underlying susceptibility to severe Toxoplasma gondii infection in activated PI3Kδ syndrome (APDS) and in other forms of primary immunodeficiency
Evaluating the Effects of Cerebrospinal Fluid Protein Content on the Performance of Differential Pressure Valves and Antisiphon Devices Using a Novel Benchtop Shunting Model
BACKGROUNDHydrocephalus is managed by surgically implanting flow-diversion technologies such as differential pressure valves and antisiphoning devices; however, such hardware is prone to failure. Extensive research has tested them in flow-controlled settings using saline or de-aerated water, yet little has been done to validate their performance in a setting recreating physiologically relevant parameters, including intracranial pressures, cerebrospinal fluid (CSF) protein content, and body position.OBJECTIVETo more accurately chart the episodic drainage characteristics of flow-diversion technology. A gravity-driven benchtop model of flow was designed and tested continuously during weeks-long trials.METHODSUsing a hydrostatic pressure gradient as the sole driving force, interval flow rates of 6 valves were examined in parallel with various fluids. Daily trials in the upright and supine positions were run with fluid output collected from distal catheters placed at alternating heights for extended intervals.RESULTSSignificant variability in flow rates was observed, both within specific individual valves across different trials and among multiple valves of the same type. These intervalve and intravalve variabilities were greatest during supine trials and with increased protein. None of the valves showed evidence of overt obstruction during 30 d of exposure to CSF containing 5 g/L protein.CONCLUSIONDay-to-day variability of ball-in-cone differential pressure shunt valves may increase overdrainage risk. Narrow-lumen high-resistance flow control devices as tested here under similar conditions appear to achieve more consistent flow rates, suggesting their use may be advantageous, and did not demonstrate any blockage or trend of decreasing flow over the 3 wk of chronic use
Digital Texts and Textual Data: A Pedagogical Anthology
This collection features pedagogical artifacts created by the participants of the 2018-2019 NEH Institute for Advanced Topics in the Digital Humanities, “Textual Data and Digital Texts in the Undergraduate Classroom.” The artifacts--assignments, syllabi, sample student work, rubrics, workshops, and more--are grouped thematically in four sections: digital exhibits and narratives, textual analysis, distant reading and data visualization, and data-driven research. Each artifact begins with an overview in which the creator summarizes the artifact type, the intended audience, the time required, and the DH method and tool used, and provides a brief description of the artifact
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