122 research outputs found

    Analysis of the phenomenon of speculative trading in one of its basic manifestations: postage stamp bubbles

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    We document and analyze the empirical facts concerning one of the clearest evidence of speculation in financial trading as observed in the postage collection stamp market. We unravel some of the mechanisms of speculative behavior which emphasize the role of fancy and collective behavior. In our conclusion, we propose a classification of speculative markets based on two parameters, namely the amplitude of the price peak and a second parameter that measures its ``sharpness''. This study is offered to anchor modeling efforts to realistic market constraints and observations.Comment: 9 pages, 5 figures and 2 tables, in press in Int. J. Mod. Phys.

    Demonstration of a robust magnonic spin wave interferometer

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    Magnonics is an emerging field dealing with ultralow power consumption logic circuits, in which the flow of spin waves, rather than electric charges, transmits and processes information. Waves, including spin waves, excel at encoding information via their phase using interference. This enables a number of inputs to be processed in one device, which offers the promise of multi-input multi-output logic gates. To realize such an integrated device, it is essential to demonstrate spin wave interferometers using spatially isotropic spin waves with high operational stability. However, spin wave reflection at the waveguide edge has previously limited the stability of interfering waves, precluding the use of isotropic spin waves, i.e., forward volume waves. Here, a spin wave absorber is demonstrated comprising a yttrium iron garnet waveguide partially covered by gold. This device is shown experimentally to be a robust spin wave interferometer using the forward volume mode, with a large ON/OFF isolation value of 13.7 dB even in magnetic fields over 30 Oe

    Development of high-throughput quantitative analytical method for l-cysteine-containing dipeptides by LC–MS/MS toward its fermentative production

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    l-Cysteine (Cys) is metabolically fundamental sulfur compound and important components in various cellular fac-tors. Interestingly, free-form Cys itself as a simple monomeric amino acid was recently shown to function in a novel antioxidative system (cysteine/cystine shuttle system) in Escherichia coli. However, as for Cys-containing dipeptides, the biological functions, effects, and even contents have still remained largely elusive. The potential functions should be a part of cellular redox system and important in basic and applied biology. For its progress, establishment of reli-able quantitation method is the first. However, such accurate analysis is unexpectedly difficult even in Cys, because thiol compounds convert through disulfide-exchange and air oxidation during sample preparation. Addressing this problem, in this study, thiol molecules like Cys-containing dipeptides were derivatized by using monobromobimane (thiol-specific alkylating reagent) and detected as S-bimanyl derivatives by liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). Sample separation was processed with a C18 column (2.1 mm × 150 mm, 1.7 μm) and with water-acetonitrile gradient mobile phase containing 0.1% (v/v) formic acid at flow rate of 0.25 ml/min. The mass spectrometer was operated in the multiple reaction monitoring in positive/negative mode with electrospray ionization. The derivatization could indeed avoid the unfavorable reactions, namely, developed the method reflecting their correct contents on sampling. Furthermore, the method was successfully applied to monitoring Cys-containing dipeptides in E. coli Cys producer overexpressing bacD gene. This is the first report of the quantitative analysis of Cys-containing dipeptides, which should be useful for further study of fermentative production of Cys-containing dipeptides

    In Vivo Microwave Ablation of Normal Swine Lung at High-power, Short-duration Settings

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    To evaluate the volume and heat-sink effects of microwave ablation (MWA) in the ablation zone of the normal swine lung. MWA at 100 W was performed for 1, 2, and 3 min in 7, 5, and 5 lung zones, respectively. We assessed the histopathology in the ablation zones and other outcome measures: namely, length of the longest long and short axes, sphericity, ellipsoid area, and ellipsoid volume. The mean long- and short-axis diameters were 22.0 and 14.1 mm in the 1-min ablation zone, 27.6 and 20.2 mm in the 2-min ablation zone; and 29.2 and 21.2 mm in the 3-min ablation zone, respectively. All measures, except sphericity, were significantly less with 1-min ablation than with either 2- or 3-min ablation. There were no significant differences between the 2- and 3-min ablation zones, but all measures except sphericity were larger with 3-min ablation. Although there were no blood vessels that resulted in a heat-sink effect within the ablation zones, the presence of bronchi nearby in 5 lung ablation zones resulted in reduced ablation size. In high-power, short-duration MWA, the lung ablation volume was affected by ablation time. Some ablations showed that a heat-sink effect by a neighboring bronchus might occur

    Impact of Right Ventricular Dilatation in Patients with Atrial Septal Defect

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    Objective. The aim of this study was to examine the relationship between right ventricular (RV) volume and exercise capacity in adult patients with atrial septal defect (ASD) and to determine the degree of RV dilatation for transcatheter ASD closure. Background. RV dilatation is an indication of transcatheter ASD closure; however, few studies have reported the clinical significance of RV dilatation. Methods. We enrolled 82 consecutive patients (mean age, 49 +/- 18 years; female, 68%) who underwent cardiac magnetic resonance imaging and symptom-limited cardiopulmonary exercise test before ASD closure. The relationship between RV volume and peak oxygen uptake (VO2) was evaluated. Results. The mean RV end-diastolic volume index was 108 +/- 27 ml/m(2) (range, 46 to 180 ml/m(2)). The mean peak VO2 was 24 +/- 7 ml/min/kg (range, 14 to 48 ml/min/kg), and the mean predicted peak VO2 was 90 +/- 23%. There were significant negative relationships of RV end-diastolic volume index with peak VO2 (r = -0.28, p= 120 ml/m(2) was related to the reduction in peak VO2. This criterion of RV dilatation may be valuable for the indication of transcatheter ASD closure

    Needle Tract Ablation in Liver Tissue Using a Cryoprobe Combined with an Electrosurgical Device: Influence of ex vivo and in vivo Animal Models

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    To assess the feasibility of needle tract ablation in liver tissue in ex vivo and in vivo animal models using a cryo-probe and electrosurgical device. The experimental device is made by inserting a cryoprobe through an intro-ducer sheath for insulation, with 2-cm of probe tip projecting out. A beagle liver was punctured by the device, and electric current was applied at 30-W with the electrosurgical knife touching the non-insulated device base. The discolored area of cut surface along the device was evaluated in 5 application-time groups (5 , 10 , 15 , 20, or 25 seconds). An ex vivo experiment was performed to determine an ablation algorithm with an appropriate application time by comparison with radiofrequency ablation (RFA) results. Thereafter, an in vivo experiment was performed to verify the algorithm’s feasibility. In the ex vivo model, the cut surface demonstrated different amounts of discolored area according to the application time. The total discolored area in the 20-seconds group was similar to that by RFA. In the in vivo model, the liver did not bleed, the total discolored area was similar to that ex vivo, and coagulation necrosis was confirmed by photomicrograph. Needle tract ablation can be per-formed using the experimental device and electrosurgical device

    Effect of suprascapular nerve injury on muscle and regenerated enthesis in a rat rotator cuff tear model

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    Background Massive rotator cuff tears (RCTs) are complicated by muscle atrophy, fibrosis, and intramuscular fatty degeneration, which are associated with postoperative tendon-to-bone healing failure and poor clinical outcomes. We evaluated muscle and enthesis changes in large tears with or without suprascapular nerve (SN) injury in a rat model. Methods Sixty-two adult Sprague-Dawley rats were divided into SN injury (+) and SN injury (–) groups (n=31 each), comprising tendon (supraspinatus [SSP]/infraspinatus [ISP]) and nerve resection and tendon resection only cases, respectively. Muscle weight measurement, histological evaluation, and biomechanical testing were performed 4, 8, and 12 weeks postoperatively. Ultrastructural analysis with block face imaging was performed 8 weeks postoperatively. Results SSP/ISP muscles in the SN injury (+) group appeared atrophic, with increased fatty tissue and decreased muscle weight, compared to those in the control and SN injury (–) groups. Immunoreactivity was only positive in the SN injury (+) group. Myofibril arrangement irregularity and mitochondrial swelling severity, along with number of fatty cells, were higher in the SN injury (+) group than in the SN injury (–) group. The bone-tendon junction enthesis was firm in the SN injury (–) group; this was atrophic and thinner in the SN injury (+) group, with decreased cell density and immature fibrocartilage. Mechanically, the tendon-bone insertion was significantly weaker in the SN injury (+) group than in the control and SN injury (+) groups. Conclusions In clinical settings, SN injury may cause severe fatty changes and inhibition of postoperative tendon healing in large RCTs. Level of evidence Basic research, controlled laboratory study
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