23 research outputs found
Disorder-induced critical exponents near a ferromagnetic quantum critical point in Mn1−xCrxSi
We report the observation of critical behavior in Mn1−xCrxSi (0≤x≤1) close to a T = 0 K quantum critical point, consistent with the Belitz-Kirkpatrick-Vojta (BKV) theory of disordered metallic ferromagnets. The critical exponents are in good agreement with the theoretical predictions of the BKV theory in the preasymptotic limit. A non-Fermi liquid-like behavior is seen down to 200 mK in the transport and thermodynamic properties around the critical concentration xC = 0.2. Quantum criticality and self-consistency of the exponents is further confirmed using a scaling analysis of the magnetization and heat capacity data. A recovery to Fermi liquid-like behavior is displayed on moving away from the critical composition, as well as with the application of a magnetic field
Quantum Griffiths phase in disordered Mn1-xFexSi
We show the presence of magnetic rare regions consistent with the quantum Griffiths phase in Fe-doped MnSi using detailed heat capacity, magnetization, and muon spin relaxation (μSR) measurements down to millikelvin temperatures. The slow dynamics of these rare regions at low temperatures leads to the non-Fermi-liquid behavior in heat capacity and magnetization. The μSR and magnetization results further indicate that the dynamics freezes into a cluster-glass state below Tf ∼ 1.25 K. The results are in agreement with theoretical models proposed in the literature for metallic systems with Heisenberg symmetry that exhibit the quantum Griffiths phase in the presence of strong disorder
Improving Network-on-Chip-based Turbo Decoder Architectures
In this work novel results concerning Networkon- Chip-based turbo decoder architectures are presented. Stemming from previous publications, this work concentrates first on improving the throughput by exploiting adaptive-bandwidth-reduction techniques. This technique shows in the best case an improvement of more than 60 Mb/s. Moreover, it is known that double-binary turbo decoders require higher area than binary ones. This characteristic has the negative effect of increasing the data width of the network nodes. Thus, the second contribution of this work is to reduce the network complexity to support doublebinary codes, by exploiting bit-level and pseudo-floatingpoint representation of the extrinsic information. These two techniques allow for an area reduction of up to more than the 40 % with a performance degradation of about 0.2 d
Mapping Tissue Optical Attenuation to Identify Cancer Using Optical Coherence Tomography
The lymphatic system is a common route for the spread of cancer and the identification of lymph node metastases is a key task during cancer surgery. This paper demonstrates the use of optical coherence tomography to construct parametric images of lymph nodes. It describes a method to automatically estimate the optical attenuation coefficient of tissue. By mapping the optical attenuation coefficient at each location in the scan, it is possible to construct a parametric image indicating variations in tissue type. The algorithm is applied to ex vivo samples of human axillary lymph nodes and validated against a histological gold standard. Results are shown illustrating the variation in optical properties between cancerous and healthy tissue
Predictive Validity of a New Self-report Measure of Individual Skin Type Through Characterization of Skin Melanin Using Reflectance Photospectroscopy
In the realm of research and dermatology, the Fitzpatrick Skin Type scale (FST) has been the gold standard of measurement to classify sun sensitivity for human’s skin. This scale is based on an individual’s dermal reaction to ultraviolet exposure (Parrish, et al., 1974; Fitzpatrick, 1975; Pathak, et al., 1976; Fitzpatrick, 1988). It was assumed in science as well as popular culture that individuals with darker skin were less susceptible to issues related to UV damage of their skin. More recent research (Eilers, et al., 2013) suggests that while melanin affords some skin protection, damage can still occur that may result in disparities of darker skin individuals getting diagnosed with skin cancer later when the disease is more advanced and deadly. This phase of the Let’s Get Healthy! sun sensitivity project compares a revised selfadministered survey with objective reflectance photospectroscopy to determine if an individual’s melanin content correlates with FST. Validation of the self-administered survey will enable better characterization of individuals and guide tailored recommendations of sun protection behaviors that may reduce their risk of skin cancer
Percolative nature of A-site disordered La<sub>0.75</sub>Ca<sub>0.25-x</sub>Sr<sub>x</sub>MnO<sub>3</sub> manganites
Spin fluctuations in Cr doped MnSi
Transport and calorimetric properties of Mn1-xCrxSi (x = 0.025) down to 2 K and magnetic fields up to 13 T are reported. Electrical resistivity in zero field as well as in magnetic fields, below a magnetic transition temperature, T-c = 23.6 K could be described using a T-2 term with large coefficient, invoking the role of spin fluctuations. Sommerfeld coefficient 'gamma' of specific heat is an enhanced one as compared to the pure MnSi. Negative magnetoresistance (35% at 13 T) with maximum at T-c and a decrease in coefficient of T-2 term in resistivity suggests the suppression of spin fluctuations in high magnetic fields. This is further supported by negative magneto-specific heat in the vicinity of T-c coupled with a decrement in the Sommerfeld coefficient 'gamma' of specific heat under a field of 10 T. Kadowaki-Woods ratio places the system close to other systems showing strong spin fluctuations. (C) 2017 Elsevier B.V. All rights reserved