Quantum Magnetic Impurities in Magnetically Ordered Systems

We discuss the problem of a spin 1/2 impurity immersed in a spin S magnetically ordered background. We show that the problem maps onto a generalization of the dissipative two level system (DTLS) with two independent heat baths, associated with the Goldstone modes of the magnet, that couple to different components of the impurity spin operator. Using analytical perturbative renormalization group (RG) methods and accurate numerical renormalization group (NRG) we show that contrary to other dissipative models there is quantum frustration of decoherence and quasi-scaling even in the strong coupling regime. We make predictions for the behavior of the impurity magnetic susceptibility that can be measured in nuclear magnetic resonance (NMR) experiments. Our results may also have relevance to quantum computation.Comment: 4 pages, 3 figure

Association of falls, fear of falling, handgrip strength and gait speed with frailty levels in the community elderly

Introduction: The Frailty Syndrome is not synonymous with disability, but may be a precursor of etiological and physiological dysfunction, which affects mobility before causing reduced functional capacity, explaining conditions of weakness, weight loss, and abnormal gait. Study design: This is an analytical, observational, cross-sectional study. Objective: To verify the association of handgrip strength, gait speed, fear of falling, and falls with the level of frailty. Methods: Study consisting of 54 participants, aged 65 and older, enrolled in a health care and monitoring government program in the municipality of Uberaba, Minas Gerais, Brazil. The volunteers were assessed for frailty, – non-frail group (NG), pre-frail group (PG), and frail group (FG) – according to the Fried criteria, and based on the outcomes of handgrip strength, gait speed, fear of falling, and falls. An inferential descriptive statistical analysis followed, with Chi-square and KruskallWallis tests performed by the Stata11.0 software. Results: In the comparative analysis between the groups studied there was statistical significance relative to handgrip strength (FG and NG), gait speed (NG and FG / NG and PG), and fear of falling (NG and FG). There was no significant difference between the levels of frailty and falls. Conclusions: Frailty is associated with reduced muscle strength, decreased gait speed, and greater fear of falling in elderly people of the communit

Yttria/ceria stabilized zirconia composites: evaluation of microstructural, mechanical and color properties for biomedical applications

[Excerpt] 3-mol% Yttria-Stabilized Tetragonal Zirconia Polycrystal (3Y-TZP), a ceramic biomaterial, has been widely used in the dentistry field due to its biocompatibility, tooth-like color and mechanical properties [1]. Despite these advantages, its physical and mechanical properties tend to degrade as a result of a low-temperature aging process induced by its sensitivity to low-temperature degradation (LTD) when it is in contact with water that is already at human body temperature [2]. Because of this, many studies have been performed aiming at avoiding this phenomenon by replacing 3Y-TZP by 12 mol% ceria stabilized tetragonal zirconia polycrystal (12Ce-TZP). Nevertheless, compared to 3Y-TZP, 12Ce-TZP has lower strength which is partly related to its larger grain size [3]. [...]This work was supported by FCT national funds, under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/2020. Additionally, this work was also supported by FCT through the grant SFRH/BD/146324/2019

Frustration of Decoherence in Open Quantum Systems

We study a model of frustration of decoherence in an open quantum system. Contrary to other dissipative ohmic impurity models, such as the Kondo model or the dissipative two-level system, the impurity model discussed here never presents overdamped dynamics even for strong coupling to the environment. We show that this unusual effect has its origins in the quantum mechanical nature of the coupling between the quantum impurity and the environment. We study the problem using analytic and numerical renormalization group methods and obtain expressions for the frequency and temperature dependence of the impurity susceptibility in different regimes.Comment: 14 pages, 5 figure

A Coulomb gas approach to the anisotropic one-dimensional Kondo lattice model at arbitrary filling

We establish a mapping of a general spin-fermion system in one dimension into a classical generalized Coulomb gas. This mapping allows a renormalization group treatment of the anisotropic Kondo chain both at and away from half-filling. We find that the phase diagram contains regions of paramagnetism, partial and full ferromagnetic order. We also use the method to analyze the phases of the Ising-Kondo chain.Comment: 19 pages, 9 figure

Phase diagram of the anisotropic Kondo chain

We establish the phase diagram of the one-dimensional anisotropic Kondo lattice model at T=0 using a generalized two-dimensional classical Coulomb gas description. We analyze the problem by means of a renormalization group (RG) treatment. We find that the phase diagram contains regions of paramagnetism, partial and full ferromagnetic order.Comment: Final version to appear in Physical Review Letter

Impact of Vutrisiran on Quality of Life and Physical Function in Patients with Hereditary Transthyretin-Mediated Amyloidosis with Polyneuropathy

INTRODUCTION: Hereditary transthyretin (ATTRv; v for variant) amyloidosis, also known as hATTR amyloidosis, is a progressive and fatal disease associated with rapid deterioration of physical function and patients' quality of life (QOL). Vutrisiran, a subcutaneously administered RNA interference (RNAi) therapeutic that reduces hepatic production of transthyretin, was assessed in patients with ATTRv amyloidosis with polyneuropathy in the pivotal HELIOS-A study. METHODS: The phase 3 open-label HELIOS-A study investigated the efficacy and safety of vutrisiran in patients with ATTRv amyloidosis with polyneuropathy, compared with an external placebo group from the APOLLO study of the RNAi therapeutic patisiran. Measures of QOL and physical function were assessed. RESULTS: At month 18, vutrisiran improved Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) total score (least squares mean difference [LSMD] in change from baseline [CFB]: –21.0; p = 1.84 × 10–10) and Norfolk QOL-DN domain scores, compared with external placebo. This benefit relative to external placebo was evident across all baseline polyneuropathy disability (PND) scores and most pronounced in patients with baseline PND scores I–II. Compared with external placebo, vutrisiran also demonstrated benefit in EuroQoL-Visual Analog Scale (EQ-VAS) score (LSMD in CFB: 13.7; nominal p = 2.21 × 10–7), 10-m walk test (LSMD in CFB: 0.239 m/s; p = 1.21 × 10–7), Rasch-built Overall Disability Score (LSMD in CFB: 8.4; p = 3.54 × 10–15), and modified body mass index (mBMI) (LSMD in CFB: 140.7; p = 4.16 × 10–15) at month 18. Overall, Norfolk QOL-DN, EQ-VAS, and mBMI improved from pretreatment baseline with vutrisiran, whereas all measures worsened from baseline in the external placebo group. At month 18, Karnofsky Performance Status was stable/improved from baseline in 58.2/13.1% with vutrisiran versus 34.7/8.1% with external placebo. CONCLUSION: Vutrisiran treatment provided significant clinical benefits in multiple measures of QOL and physical function in patients with ATTRv amyloidosis with polyneuropathy. Benefits were most pronounced in patients with earlier-stage disease, highlighting the importance of early diagnosis and treatment