First-order phase transitions are accompanied by a latent heat. Consequently, manipulating them by means of an external field causes a caloric effect. Although transitions from antiferromagnetic to paramagnetic states are not controlled by a magnetic field, a large barocaloric effect is expected when strong cross-correlations between the volume and magnetic order occur. Here we examine how geometric frustration in itinerant antiferromagnetic compounds can enhance the barocaloric effect. We study the thermodynamic behaviour of the frustrated antiferromagnet Mn3GaN, and report an entropy change of 22.3 J kg(-1) K(-1) that is concomitant with a hydrostatic pressure change of 139 MPa. Furthermore, the calculated value of the adiabatic temperature change reaches 5 K by depressurization of 93 MPa. The giant barocaloric effect in Mn3GaN is caused by a frustration-driven enhancement of the ratio of volume change against the pressure coefficient of the Néel temperature. This mechanism for enhancing the barocaloric effect can form the basis for a new class of materials for solid-state refrigerants.

The temperature dependence of the upper critical magnetic field (H c2 ) in a BaFe 1.84 Co 0.16 As 2 single crystal was determined via resistivity, for the inter-plane (H⊥ab) and in-plane (H//ab) directions in pulsed and static magnetic fields of up to 60 T. Suppressing superconductivity in a pulsed magnetic field at 3 He temperatures permits us to construct an H-T phase diagram from quantitative H c2 (0) values and determine its behavior in low temperatures. Hc 2 (0) with H//ab (H c2// (0)) and H⊥ab (H c2⊥ (0)) are ~ 55 T and 50 T respectively. These values are ~ 1.2 -1.4 times larger than the weak-coupling Pauli paramagnetic limit (H p = 1.84 T c ), indicating that enhanced paramagnetic limiting is essential and this superconductor is unconventional. While H c2// ab is saturated at low temperature, H c2 with H⊥ab (H c2⊥ ) exhibits almost linear temperature dependence towards T = 0 K which results in reduced anisotropy of H c2 in low temperature. The anisotropy of H c2 was ~ 3.4 near T c , and decreases rapidly with lower temperatures reaching ~ 1.1 at T = 0.7 K.

Deep low frequency tremors are indicators of slow slip transients in the brittle-ductile transition zone along subducting plates. Investigation of comprehensive tremor activities is therefore an important issue for understanding the seismic/aseismic characteristics in transition zones. Here, we focus on the radiated energy from tremors to reveal the along-strike heterogeneity in the strength of tremor patches. Based on a tremor catalog that more accurately evaluates radiated energy, we examine the spatio-temporal activity of tremors accompanied by slow slip events (SSEs) in western Shikoku, southwestern Japan. The new finding of this study is that the energy radiated from tremors is positively correlated with the speed of tremor migration front and the slip rate along the plate interface during a SSE. This can be qualitatively explained by a stress diffusion model, which consists of along-strike heterogeneities in the effective strength of tremor patches embedded in a ductile shear zone. This effective strength heterogeneity is supported by a lateral variation in the stress drop of a SSE; it is consistent with the fluid pressure distribution along the plate boundary fault and the tidal sensitivity of tremors. Accurate evaluation of tremor activities, especially the radiated energy, can be used to infer the spatial distribution of the strength of tremor patches in transition zones worldwide.

We conducted uniaxial compression and grain growth experiments on fine‐grained (~1 μm) forsterite +20 vol% enstatite aggregates. Based on analyses of the sensitivity of the strain rate as a function of stress, we find power law creep at low stress, Newtonian creep at intermediate stress, and again power law creep at high stress, which correspond to interface‐controlled diffusion creep, grain boundary diffusion (Coble) creep, and a dislocation‐controlled process, respectively. The creep rate of these samples is well expressed by a combination of strain rates of these three mechanisms where interface‐controlled and Coble creep rates are combined as series‐sequential processes, while the rate of the dislocation process is added with them as a parallel‐concurrent process. Mechanical data collected continuously during the application of a constant load but while slowly changing temperature were decomposed into data for every 1 °C, which allowed consideration of >600 mechanical data points from 1054 to 1370 °C. The data were analyzed using Bayesian statistics implementing a Markov chain Monte Carlo method imposed on the above constitutive equation, resulting in the best fit flow law parameters for interface‐controlled and Coble creep. Samples were annealed for 500 hr at various temperatures. A comparison of the final grain sizes as a function of temperature on an Arrhenius plot resulted in an activation energy for grain growth similar to that observed for grain boundary diffusion during Coble creep of these materials.

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Data assimilation (DA) is a fundamental computational technique that integrates numerical simulation models and observation data on the basis of Bayesian statistics. Originally developed for meteorology, especially weather forecasting, DA is now an accepted technique in various scientific fields. One key issue that remains controversial is the implementation of DA in massive simulation models under the constraints of limited computation time and resources. In this paper, we propose an adjoint-based DA method for massive autonomous models that produces optimum estimates and their uncertainties within reasonable computation time and resource constraints. The uncertainties are given as several diagonal elements of an inverse Hessian matrix, which is the covariance matrix of a normal distribution that approximates the target posterior probability density function in the neighborhood of the optimum. Conventional algorithms for deriving the inverse Hessian matrix require O(CN^{2}+N^{3}) computations and O(N^{2}) memory, where N is the number of degrees of freedom of a given autonomous system and C is the number of computations needed to simulate time series of suitable length. The proposed method using a second-order adjoint method allows us to directly evaluate the diagonal elements of the inverse Hessian matrix without computing all of its elements. This drastically reduces the number of computations to O(C) and the amount of memory to O(N) for each diagonal element. The proposed method is validated through numerical tests using a massive two-dimensional Kobayashi phase-field model. We confirm that the proposed method correctly reproduces the parameter and initial state assumed in advance, and successfully evaluates the uncertainty of the parameter. Such information regarding uncertainty is valuable, as it can be used to optimize the design of experiments.

Object: Age-related morphological changes in the human hyoid bone were investigated radiographically and histologically. Materials and Methods: Thirty-two measurements were performed on radiographs of 238 hyoid bones from autopsy cases of known age and sex. Thirty-one hyoid bones that were studied by radiography were also examined histologically in horizontal sections. Results: Analysis of the length and width of the hyoid bone revealed significant increases in the body and the anterior part of the greater cornu and a significant decrease in the posterior part of the greater cornu with aging. Most measurements of the body and the greater cornu revealed differences between male and female hyoid bones. The outer margins of the body and the greater cornu were situated further outside in older males compared with females. The breadth of the joint space showed a significant age-related decrease, and the degree of fusion showed a significant age-related increase. Histological findings showed ossified or calcified fusion, with osteoclasts in the marginal area of the joint space. Conclusions: Increasing age induces fusion of the body and the greater cornu. The morphometric changes in the shape of the hyoid bone may represent functional adaptation to articulation fixation.