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1.
Phys Rev Lett ; 132(24): 246702, 2024 Jun 14.
Article in English | MEDLINE | ID: mdl-38949369

ABSTRACT

Materials manifesting the Kitaev model, characterized by bond-dependent interactions on a honeycomb lattice, can host exotic phenomena like quantum spin liquid states and topological magnetic excitations. However, finding such materials remains a formidable challenge. Here, we report high-resolution inelastic neutron scattering measurements performed on VI_{3}, a van der Waals ferromagnetic Mott insulator, covering a wide range of reciprocal space. Our measurements unveil highly anisotropic magnetic excitations in momentum space. Through a comprehensive comparative analysis of various models that incorporate diverse symmetry-allowed magnetic interactions, we find the observed excitations are well captured by a model with a large bond-dependent Kitaev interaction. These results not only help to understand the intriguing properties of VI_{3}, such as the pronounced anomalous thermal Hall effects and strong pressure or structure dependence of magnetism, but also open a new avenue for exploring Kitaev physics.

2.
Sci Bull (Beijing) ; 67(1): 38-44, 2022 Jan.
Article in English | MEDLINE | ID: mdl-36545957

ABSTRACT

We report thermodynamic and neutron scattering measurements of the triangular-lattice quantum Ising magnet TmMgGaO4 in longitudinal magnetic fields. Our experiments reveal a quasi-plateau state induced by quantum fluctuations. This state exhibits an unconventional non-monotonic field and temperature dependence of the magnetic order and excitation gap. In the high field regime where the quantum fluctuations are largely suppressed, we observed a disordered state with coherent magnon-like excitations despite the suppression of the spin excitation intensity. Through detailed semi-classical calculations, we are able to understand these behaviors quantitatively from the subtle competition between quantum fluctuations and frustrated Ising interactions.

3.
Nat Commun ; 13(1): 4037, 2022 Jul 12.
Article in English | MEDLINE | ID: mdl-35821370

ABSTRACT

Spin and lattice are two fundamental degrees of freedom in a solid, and their fluctuations about the equilibrium values in a magnetic ordered crystalline lattice form quasiparticles termed magnons (spin waves) and phonons (lattice waves), respectively. In most materials with strong spin-lattice coupling (SLC), the interaction of spin and lattice induces energy gaps in the spin wave dispersion at the nominal intersections of magnon and phonon modes. Here we use neutron scattering to show that in the two-dimensional (2D) van der Waals honeycomb lattice ferromagnetic CrGeTe3, spin waves propagating within the 2D plane exhibit an anomalous dispersion, damping, and breakdown of quasiparticle conservation, while magnons along the c axis behave as expected for a local moment ferromagnet. These results indicate the presence of dynamical SLC arising from the zero-temperature quantum fluctuations in CrGeTe3, suggesting that the observed in-plane spin waves are mixed spin and lattice quasiparticles fundamentally different from pure magnons and phonons.

4.
Cardiovasc Interv Ther ; 37(2): 354-362, 2022 Apr.
Article in English | MEDLINE | ID: mdl-34333753

ABSTRACT

This study aims to test the hypothesis that the effect of excimer laser coronary angioplasty (ELCA) not only vaporizes thrombi and their underlying coronary plaque, it also changes their quality. We performed a series of cross-sectional analyses in 52 lesions in 51 patients before and after ELCA with integrated backscatter-intravascular ultrasound (IB-IVUS). The constituent parts of the plaque can be assessed by IB-IVUS (i.e., calcified, fibrous, lipid) according to integrated backscatter values. Minimum lumen diameter, lumen volume and vessel volume expanded after ELCA, while plaque volume did not significantly decrease. There was also a decrease of 'lipid' component (35.4-30.3%, P < 0.001) and an increase of IB-IVUS-derived 'fibrous' part (34.5-38.3%, P < 0.001). These results may help in understanding plaque change after ELCA. Excimer laser coronary angioplasty seems to contribute to the modification of coronary plaque composition in addition to debulking it.


Subject(s)
Atherectomy, Coronary , Coronary Artery Disease , Plaque, Atherosclerotic , Coronary Angiography , Coronary Artery Disease/diagnostic imaging , Coronary Artery Disease/surgery , Cross-Sectional Studies , Humans , Lasers, Excimer/therapeutic use , Plaque, Atherosclerotic/diagnostic imaging , Plaque, Atherosclerotic/surgery , Ultrasonography, Interventional/methods
5.
Sci Rep ; 9(1): 1826, 2019 Feb 12.
Article in English | MEDLINE | ID: mdl-30755692

ABSTRACT

Molecular based spin-1/2 triangular lattice systems such as LiZn2Mo3O8 have attracted research interest. Distortions, defects, and intersite disorder are suppressed in such molecular-based magnets, and intrinsic geometrical frustration gives rise to unconventional and unexpected ground states. Li2AMo3O8 (A = In or Sc) is such a compound where spin-1/2 Mo3O13 clusters in place of Mo ions form the uniform triangular lattice. Their ground states are different according to the A site. Li2InMo3O8 undergoes conventional 120° long-range magnetic order below TN = 12 K whereas isomorphic Li2ScMo3O8 exhibits no long-range magnetic order down to 0.5 K. Here, we report exotic magnetisms in Li2InMo3O8 and Li2ScMo3O8 investigated by muon spin rotation (µSR) and inelastic neutron scattering (INS) spectroscopies using polycrystalline samples. Li2InMo3O8 and Li2ScMo3O8 show completely different behaviors observed in both µSR and INS measurements, representing their different ground states. Li2InMo3O8 exhibits spin wave excitation which is quantitatively described by the nearest neighbor anisotropic Heisenberg model based on the 120° spin structure. In contrast, Li2ScMo3O8 undergoes short-range magnetic order below 4 K with quantum-spin-liquid-like magnetic fluctuations down to the base temperature. Origin of the different ground states is discussed in terms of anisotropies of crystal structures and magnetic interactions.

6.
Eur J Radiol ; 108: 155-164, 2018 Nov.
Article in English | MEDLINE | ID: mdl-30396649

ABSTRACT

Muscle injury accounts for about one-third of total sports-related injuries. The lower limb muscles have one of the highest predisposition for injury in high-level professional athletic sports, such as the National Football League. The commonest group of muscles injured among football players include the hamstrings, followed by the quadriceps. Muscle injuries lead to significant time, off the field and affect return to play. Sports physicians and teams have been keen on assessing such injuries and also relying on multiple tools to safely return the player back to the field. MRI plays a key role in evaluation, follow-up, and assessment for return to play (RTP). In this review, we will discuss details of muscle anatomy, incidence of muscle injuries, injury mechanisms, and use of MRI in assessment, grading, follow-up and in predicting the natural course of muscle injuries in the high-end athletic players. While the use of MRI is clear in diagnosis, and for follow up of muscle injuries, there is some limitation in its ability to predict RTP, based on current MRI classification systems. Footballers who have clinical injuries without MRI evidence of significant muscle injury (grade 0 and 1) have a shorter period of RTP. Injuries classified as high grade (3 and 4) on MRI do not correlate well with time to RTP. Further trials are required to improve the capability of MRI in its prediction of RTP.


Subject(s)
Athletic Injuries/diagnostic imaging , Athletic Performance/statistics & numerical data , Football , Magnetic Resonance Imaging/methods , Muscle, Skeletal/injuries , Return to Sport/statistics & numerical data , Adult , Athletes/statistics & numerical data , Athletic Injuries/rehabilitation , Humans , Male , Muscle, Skeletal/diagnostic imaging , Predictive Value of Tests , Reproducibility of Results , United States
7.
Radiol Clin North Am ; 56(6): 917-934, 2018 Nov.
Article in English | MEDLINE | ID: mdl-30322490

ABSTRACT

The foot and ankle delicately balance the need for support of the weight of the human body, with the need for flexibility. Palpable masses about the foot and ankle, therefore, are most commonly related to trauma or mechanical instability. Non-neoplastic causes, such as ganglion cysts and callus, therefore, predominate. However, the radiologist must be aware of the imaging appearance of less common benign and malignant neoplasms that can involve the foot and ankle.


Subject(s)
Ankle/pathology , Bone Neoplasms/diagnostic imaging , Foot/pathology , Soft Tissue Neoplasms/diagnostic imaging , Ankle/anatomy & histology , Diagnosis, Differential , Foot/anatomy & histology , Humans
8.
Sci Rep ; 8(1): 9651, 2018 Jun 25.
Article in English | MEDLINE | ID: mdl-29941897

ABSTRACT

The electron-doped SrTiO3 exhibits good thermoelectric properties, which makes this material a promising candidate of an n-type oxide thermoelectric device. Recent studies indicated that only a few percent co-doping of La and Mn in SrTiO3 substantially reduces the thermal conductivity, thereby greatly improving the thermoelectric figure of merit at room temperature. Our time-of-flight neutron scattering studies revealed that by doping both La and Mn into SrTiO3, the inelastic scattering spectrum shows a momentum-independent increase in the low-energy spectral weight approximately below 10 meV. The increase in the low-energy spectral weight exhibits a clear correlation with thermal conductivity. The correlation is attributed to dynamical and local structural fluctuations caused by the Jahn-Teller instability in Mn3+ ions coupled with the incipient ferroelectric nature of SrTiO3, as the origin of the low thermal conductivity.

9.
J Med Case Rep ; 7: 129, 2013 May 13.
Article in English | MEDLINE | ID: mdl-23668918

ABSTRACT

INTRODUCTION: The clinical presentation of eosinophilic myocarditis may vary from asymptomatic to the manifestation of severe symptoms, including cardiac tamponade and arrhythmias. In pregnant patients with this condition, drugs must be used cautiously up to approximately the 4th month of pregnancy because drug use should be limited during the period of fetal organogenesis. CASE PRESENTATION: A 30-year-old Asian woman at 14 weeks of pregnancy with progressive malaise was hospitalized. The electrocardiogram revealed ST elevation and low QRS voltage. Echocardiography revealed massive pericardial effusion and myocardial swelling. A laboratory examination revealed an increase in her white blood cell count, with a predominance of neutrophils. Pericardial drainage was performed for relief of the cardiac tamponade. The pericardial effusion revealed an abundance of eosinophils. Subsequently, the peripheral blood eosinophil count began to rise, and the patient was clinically diagnosed with eosinophilic myopericarditis. The patient's condition improved rapidly following the initiation of prednisolone treatment, and she finally delivered a full-term normal infant. CONCLUSIONS: A patient with clinically suspected myopericarditis in the early stage of pregnancy who improved rapidly with pericardial drainage and prednisolone therapy, and successfully delivered a normal full-term infant; the diagnosis was made in the early stage of the disease, based on the detection of an abundance of eosinophils in the pericardial effusion preceding the subsequent development of peripheral blood eosinophilia.

10.
J Pharmacol Exp Ther ; 329(3): 1006-15, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19276400

ABSTRACT

3,4-Methylenedioxymethamphetamine (MDMA) is a drug of abuse with mixed stimulant- and hallucinogen-like effects. The aims of the present studies were to establish discrimination of S(+)-MDMA, R(-)-MDMA, or their combination as racemic MDMA in separate groups of mice to assess cross-substitution tests among all three compounds, to determine the time courses of the training doses, to assess pharmacokinetic variables after single injections and after cumulative dosing, and to define the metabolic dispositions of MDMA enantiomers and their metabolites. All three forms of MDMA served as discriminative stimuli, and with the exception of R(-)-MDMA in mice trained to discriminate the racemate, compounds substituted for one another. The onset of interoceptive effects for S(+)-MDMA and racemic MDMA were faster than for R(-)-MDMA, and the duration of discriminative stimulus effects was shortest for R(-)-MDMA. S(+)-MDMA and its metabolites were found in higher concentrations than R(-)-MDMA and its metabolites after a bolus dose of racemic MDMA. The N-dealkylation pathway is favored in mouse plasma with MDA as the main metabolite formed. Cumulative doses of MDMA lead to higher plasma concentrations compared with an equivalent single dose. 3,4-Methylenedioxyamphetamine (MDA) concentrations are lower after the cumulative dose compared with the single dose, which, coupled with the nonlinearity observed in MDMA pharmacokinetics after increased doses of racemic MDMA, suggests autoinhibition (or saturation) of MDMA metabolism in mice. In total, these studies suggest that the discriminative stimulus effects of racemic MDMA are perhaps driven by accumulation of S(+)-MDMA and S(+)-MDA in the mouse.


Subject(s)
Discrimination Learning/drug effects , N-Methyl-3,4-methylenedioxyamphetamine/pharmacology , N-Methyl-3,4-methylenedioxyamphetamine/pharmacokinetics , Animals , Behavior, Animal/drug effects , Hallucinogens/metabolism , Hallucinogens/pharmacokinetics , Hallucinogens/pharmacology , Male , Mice , N-Methyl-3,4-methylenedioxyamphetamine/metabolism , Reinforcement, Psychology , Stereoisomerism , Structure-Activity Relationship , Time Factors
11.
Circ J ; 71(6): 911-4, 2007 Jun.
Article in English | MEDLINE | ID: mdl-17526989

ABSTRACT

BACKGROUND: The ability to evaluate coronary stenosis using multi-detector computed tomography (MDCT) has been well discussed. In contrast, several studies demonstrated that the plaque burden measured by intravascular ultrasound (IVUS) has a relationship to the risk of cardiovascular events. the accuracy of MDCT was studied to determine plaque and vessel size compared with IVUS. METHODS AND RESULTS: Fifty-six proximal lesions (American College of Cardiology/American Heart Association classification: segment 1, 5, 6) from 33 patients were assessed using MDCT and IVUS. The plaque and vessel area were measured from the cross-sectional image using both MDCT and IVUS. Eight coronary artery lesions with motion artifacts and heavily calcified plaques were excluded from the analysis. The vessel and lumen size evaluated using MDCT were closely correlated with those evaluated by IVUS (R(2)=0.614, 0.750 respectively). Furthermore, there was a strong correlation between percentage plaque area assessed by MDCT and IVUS (R(2)=0.824). CONCLUSION: MDCT can noninvasively quantify coronary atherosclerotic plaque with good correlation compared with IVUS in patients with atherosclerosis.


Subject(s)
Coronary Artery Disease/diagnostic imaging , Tomography, X-Ray Computed , Aged , Coronary Vessels/diagnostic imaging , Female , Humans , Male , Middle Aged , Predictive Value of Tests , Retrospective Studies , Ultrasonography, Interventional
12.
Neurol Med Chir (Tokyo) ; 45(5): 277-9, 2005 May.
Article in English | MEDLINE | ID: mdl-15914971

ABSTRACT

A 61-year-old female complained of low back pain, and had been treated by spinal anesthetic injection more than 70 times over 14 years. Magnetic resonance (MR) imaging, performed at the age of 47 years, revealed no abnormal lesion. However, she developed irritable hypesthetic pain in the left leg at 61 years of age. MR imaging revealed a round mass appearing isointense on the T1-weighted and slightly hyperintense on the T2-weighted images. Laminectomy revealed an epidermoid cyst, which was removed. This case clearly demonstrates that adults can acquire epidermoid tumor which very probably has an iatrogenic origin. The incidence of epidermoid tumor is low, but we should be aware of the potential adverse complications such as formation of epidermoid tumors after lumbar puncture.


Subject(s)
Epidermal Cyst/etiology , Epidermal Cyst/pathology , Lumbar Vertebrae , Spinal Diseases/etiology , Spinal Diseases/pathology , Spinal Puncture/adverse effects , Epidermal Cyst/surgery , Female , Humans , Middle Aged , Spinal Diseases/surgery
13.
J Leukoc Biol ; 73(4): 456-63, 2003 Apr.
Article in English | MEDLINE | ID: mdl-12660220

ABSTRACT

Granulocyte apoptosis and subsequent clearance by phagocytes are critical for the resolution of inflammation. However, no studies have addressed how the resolution proceeds in the inflammatory site. We studied the time course of neutrophil apoptosis and the following ingestion by mononuclear leukocytes in rat carrageenin-induced pleurisy, detecting DNA fragmentation by the deoxyuridine triphosphate-biotin nick-end labeling (TUNEL) method, by acridine orange staining, and from the DNA ladder pattern on electrophoresis. Neutrophil accumulation started 3-5 h after carrageenin injection and then maintained a plateau until 24 h. Neutrophils decreased steeply between days 1 and 3. Mononuclear leukocytes started to accumulate at 5 h and reached a peak at day 2. TUNEL-positive bodies and acridine orange-positive bodies first became detectable in the cytoplasm of the mononuclear leukocytes from 24 h and 9 h, respectively. Both methods indicated that mononuclear leukocytes containing fragmented DNA increased rapidly on days 1 and 2 and reached a peak at day 3. The characteristic ladder pattern of neutrophil DNA was observed from 5 h. Tumor necrosis factor alpha was detectable on the start, and the levels of interleukin-10 and transforming growth factor-beta1 rose together with signs of neutrophil apoptosis and the following ingestion by mononuclear leukocytes. These results indicate that neutrophils start to undergo apoptosis just after the beginning of their accumulation in the inflammation site. Thus, evolution and resolution processes may proceed concurrently in acute inflammation.


Subject(s)
Apoptosis , Neutrophils/pathology , Pleurisy/physiopathology , Acridine Orange , Animals , Carrageenan/toxicity , DNA/metabolism , In Situ Nick-End Labeling , Interleukin-10/metabolism , Leukocytes, Mononuclear/physiology , Male , Phagocytosis/physiology , Pleurisy/chemically induced , Rats , Rats, Sprague-Dawley , Transforming Growth Factor beta/metabolism , Transforming Growth Factor beta1 , Tumor Necrosis Factor-alpha/metabolism
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