Using exact numerical techniques, we investigate the nature of excitonic (electron-hole) bound states and the development of exciton coherence in the one-dimensional half-filled extended ...Falicov-Kimball model. The ground-state phase diagram of the model exhibits, besides band-insulator and staggered orbital ordered phases, an excitonic insulator (EI) with power-law correlations. The criticality of the EI state shows up in the von Neumann entropy. The anomalous spectral function and condensation amplitude provide the binding energy and coherence length of the electron-hole pairs which, on their part, point towards a Coulomb interaction driven crossover from BCS-like electron-hole pairing fluctuations to tightly bound excitons. We show that while a mass imbalance between electrons and holes does not affect the location of the BCS-BEC crossover regime, it favors staggered orbital ordering to the disadvantage of the EI. Within the Bose-Einstein condensation (BEC) regime, the quasiparticle dispersion develops a flat valence-band top, in accord with the experimental finding for Ta2NiSe5.
The variational cluster approximation is used to study the spontaneous symmetry breaking of the excitonic insulator (EI) state in the two-orbital Hubbard model defined on the two-dimensional square ...lattice. Evaluating the order parameter of the EI state, staggered magnetization, and number of particles on each orbital, we obtain the ground-state phase diagram of the model in a wide parameter space of the intra and interorbital Coulomb interactions. We also calculate the single-particle and anomalous Green's functions. We show that the normal metallic phase is unstable to the formation of the EI state and the EI phase appears in a wide parameter region between the band-insulator and Mott-insulator phases.
Although seafloor massive sulfide (SMS) deposits are crucially important metal resources that contain high‐grade metals such as copper, lead, and zinc, their internal structures and generation ...mechanisms remain unclear. This study obtained detailed near‐seafloor images of electrical resistivity in a hydrothermal field off Okinawa, southwestern Japan, using deep‐towed marine electrical resistivity tomography. The image clarified a semi‐layered resistivity structure, interpreted as SMS deposits exposed on the seafloor, and another deep‐seated SMS layer at about 40‐m depth below the seafloor. The images reinforce our inference of a new mechanism of SMS evolution: Upwelling hydrothermal fluid is trapped under less‐permeable cap rock. The deeper embedded SMS accumulates there. Then hydrothermal fluids expelled on the seafloor form exposed SMS deposits.
Plain Language Summary
Hydrothermal circulation of seawater through the permeable ocean crust engenders formation of seafloor massive sulfide (SMS) deposits, which present high potential for metal mining. Geophysical surveys using modes such as electrical and electromagnetic methods have revealed that SMS deposits exhibit lower resistivity than the surrounding host rock. However, because detailed geophysical images of internal structures of SMS deposits are lacking, the spatial distribution of SMS deposits and the evolutionary processes of SMS deposits remain unclear. For this study, we applied a deep‐towed marine electrical resistivity tomography (ERT) system to capture detailed images of electrical resistivity structures of SMS deposits in the Iheya North hydrothermal field, Okinawa Trough, southwestern Japan. An optimal sub‐seafloor resistivity section reveals a semi‐layered structure consisting of double low‐resistivity SMS layers: exposed and deep‐seated ones. Between the SMS layers, a cap rock layer is recognized as a moderately resistive zone. This detailed structure offers an explanation of how the SMS deposits accumulate: Hydrothermal fluids upwelling from the deep crust are trapped by less‐permeable cap rock, which results in the precipitation and accumulation of SMS deposits below the cap rock. Then fluids passing through the cap rock to the seafloor produce SMS deposits on the seafloor.
Key Points
Deep‐towed marine electrical resistivity tomography revealed massive sulfide deposits on the seafloor as low‐resistivity zones
Low‐resistivity zones are semi‐layered with deposits exposed on the seafloor and other deposits at 40‐m depth below the seafloor
Detailed near‐seafloor images of electrical resistivity offer an explanation of how the SMS deposits accumulate
We report on small-cluster exact-diagonalization calculations which prove the formation of electron-hole pairs (excitons) as a prerequisite for spontaneous interlayer phase coherence in double-layer ...systems described by the extended Falicov-Kimball model. Evaluating the anomalous Green's function and momentum distribution function of the pairs, and thereby analyzing the dependence of the exciton binding energy, condensation amplitude, and coherence length on the Coulomb interaction strength, we demonstrate a crossover between a BCS-like electron-hole pairing transition and a Bose-Einstein condensation of tightly bound preformed excitons. We furthermore show that a mass imbalance between electrons and holes tends to suppress the condensation of excitons.
Abstract In addition to cognitive impairment, behavioral and psychological symptoms of dementia (BPSD) are another important aspect of most dementia patients. This study was designed for a new simple ...assessment of BPSD. We first employed a clinical survey for the local community with sending an inquiry letter to all members (n = 129) of dementia caregiver society, and then attempted to create a new BPSD score for dementia with 10 BPSD items. This new simple BPSD score was compared to a standard-detailed BPSD score neuropsychiatric inventory (NPI) for a possible correlation (n = 792) and a time to complete (n = 136). Inter-rater reliability was examined comparing scores between main and second caregivers (n = 70) for AD. Based on the clinical survey for local caregivers, a new BPSD score for dementia (ABS, Abe's BPSD score) was newly created, in which each BPSD item was allotted by an already-weighted score (maximum 1–9) based on the frequency and severity, and was finalized with taking temporal occurrences into account. ABS was filled by the main caregiver with a full score of 44, was well correlated with NPI (r = 0.716, **p < 0.01) in 792 AD patients (age 78.6 ± 7.0 years, MMSE 19.0 ± 5.9), and took a shorter time as only 56.8 ± 38.8 s (**p < 0.01) than NPI score (132.7 ± 94.0 s) with 136 AD patients. A high inter-rater reliability was obtained (r = 0.964, **p < 0.01) with a little smaller score (0.877 time) of ABS in secondary than the main caregivers. ABS provides a new simple and quick test for BPSD assessment, with a good correlation to NPI but a shorter time, and with a high inter-rater reliability. Thus ABS is useful for evaluating BPSD for mild to moderate dementia patients.
Objectives
Swallowing function is critical for continuing oral feeding to prevent frailty in older adults. In this study, we investigated the impact of tongue pressure and pulmonary function on the ...nutritional status of older adults.
Design, Setting, Participants
This cross-sectional study was conducted in Kitakyushu, Japan from August 2017 to November 2018. Fifty-two residents aged >65 years of age from three nursing care insurance facilities in Kitakyushu City, Japan were recruited.
Measurements
Oral health status, swallowing function, nutritional status using a mini nutritional assessment short form (MNA-SF), cognitive function, activities of daily living, peak expiratory flow rate (PEFR) for pulmonary function, and tongue pressure were assessed. The associations between nutritional status and the above factors were analysed using a logistic regression model.
Results
Participants were divided into two groups: well-nourished group (MNA-SF ≤12) and undernutrition group (MNA-SF <12). Multivariate logistic regression analysis revealed that the correlations of PEFR odds ratio (OR) = 0.23, 95% confidence interval (CI) = 0.23.0.89 p=0.033) and tongue pressure (OR = 0.88, 95% CI = 0.88.0.99, p=0.029) remained significant even after adjustment with possible confounders.
Conclusion
Maximum tongue pressure and PEFR in older adults were significantly associated with their nutritional status. These findings suggest that maintaining oral and pulmonary function may be a preventive factor against a decrease in the nutritional status of older frail adults.
Highlights ► nPt functions as a strong free radical scavenger in acute cerebral ischemia of mice. ► nPt ameliorates neurological function and brain damage in acute cerebral infarction. ► Ischemic ...damage was worsened by tPA, but such deterioration was prevented by nPt. ► In vivo imaging of MMP was well correlated to acute cerebral ischemic damage. ► nPt showed neuroprotective effect on neurovascular unit and inactivated MMP-9.
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