Onset Temperatures for Superconducting Fluctuations in Te-annealed FeTe1−x_{1-x}Sex_x Single Crystals: Evidence for the BCS-BEC Crossover

Recently, the superconductors' community has witnessed an unsettled debate regarding whether iron-based superconductors, in particular FeSe and FeSe$_{1-x}$S$_x$, are in the Bardeen-Cooper-Shrieffer (BCS) - Bose-Einstein condensation (BEC) crossover regime. Nonetheless, one particular system, FeTe$_{1-x}$Se$_x$, has been less investigated in this regard owing to the screening of its intrinsic superconducting properties by the inevitable iron excess. Herein, the onset temperatures for superconducting fluctuations ($T_{scf}$) are investigated by measuring the magnetoresistance (MR) of Te-annealed, high-quality FeTe$_{1-x}$Se$_x$ ($x$ = 0.1, 0.2, 0.3, and 0.4) single crystals. The results reveal very high $T_{scf}$ values for these crystals. Particularly for $x$ = 0.4, $T_{scf}$ reaches approximately 40 K, which is 2.7 times larger than $T_c$. This indicates that the superconductivity of the FeTe$_{1-x}$Se$_x$ system is well within the BCS-BEC crossover regime.Comment: 6 pages, 3 figures, and 1 table. to be published in JPS Conference Proceeding

Dynamics of quantum cellular automata electron transition in triple quantum dots

The quantum cellular automata (QCA) effect is a transition in which multiple electron move coordinately by Coulomb interactions and observed in multiple quantum dots. This effect will be useful for realizing and improving quantum cellular automata and information transfer using multiple electron transfer. In this paper, we investigate the real-time dynamics of the QCA charge transitions in a triple quantum dot by using fast charge-state readout realized by rf reflectometry. We observe real-time charge transitions and analyze the tunneling rate comparing with the first-order tunneling processes. We also measure the gate voltage dependence of the QCA transition and show that it can be controlled by the voltage.Comment: 11pages, 4 figure

Disseminated Mycobacterium genavense infection mimicking TAFRO syndrome

TAFRO syndrome is a rare variant of idiopathic multicentric Castleman's disease, for which disseminated non-tuberculous mycobacteria (NTM) infection must be excluded. However, due to the slow and fastidious growth of the organisms, identification of the pathogen is often challenging. We herein describe a case of disseminated Mycobacterium genavence infection, in which manifestations of the patient were confusingly similar to those of TAFRO syndrome. A 69-year-old Japanese man presented with prolonged fever accompanying pain in his back and ribs on the right side. Systemic investigations revealed thrombocytopenia, marked elevation of alkaline phosphatase, anasarca (pleural effusion and ascites), megakaryocytosis in the bone marrow, and hepatomegaly. Magnetic resonance imaging (MRI) showed diffuse, T1-and T2-low-intensity spotted lesions on his vertebral bodies, but biopsy showed inconclusive results. The patient met the diagnostic criteria of TAFRO syndrome and was started on prednisolone, which improved his general condition shortly thereafter. Blood culture after 42 days of incubation revealed the presence of Mycobacterium; however, we considered it a contamination at that time because no organisms grew on conventional agars, and the patient was discharged. Ten weeks after the isolation of Mycobacterium, he developed persistent fever and was readmitted. This time, vertebral bone mallow biopsy demonstrated a large amount of mycobacterium, which was later successfully identified as M. genavense by sequencing analysis. Under a final diagnosis of disseminated M. genavense infection, we treated the patient with clarithromycin, rifampicin, and ethambutol. This case highlighted that disseminated NTM infection may follow a similar clinical course as that of TAFRO syndrome

Mycobacterium chelonae bloodstream infection induced by osteomyelitis of toe: A case report

Mycobacterium chelonae is a rapidly growing mycobacterium that has the potential to cause refractory infections in humans. Mycobacteremia resulting from the organism is extremely rare, and its clinical features are yet to be uncovered. We herein present a case of M. chelonae bloodstream infection involving an immunocompromised older patient. A 79-year-old woman, on a long-term treatment with prednisolone plus tacrolimus for rheumatoid arthritis, visited our outpatient department complaining of deteriorating pain and swelling at her right 1st toe. Laboratory parameters showed elevated C-reactive protein and leukocytosis, and magnetic resonance imaging indicated osteomyelitis at the proximal phalanx of her right 1st toe. Considering the refractory course, the infected toe was immediately amputated. M. chelonae was isolated from bacterial cultures of the resected tissue and blood (BD BACTEC™ FX blood culture system, Becton Dickinson, Sparks, MD, USA), leading to a diagnosis of disseminated M. chelonae infection. We treated the patient with an antibiotic combination of clarithromycin, minocycline, and imipenem (2 weeks), which was converted to oral therapy of clarithromycin, doxycycline, and levofloxacin. This case highlighted the potential pathogenesis of M. chelonae to cause mycobacteremia in an immunocompromised patient