A role of constraint in self-organization

In this paper we introduce a neural network model of self-organization. This model uses a variation of Hebb rule for updating its synaptic weights, and surely converges to the equilibrium status. The key point of the convergence is the update rule that constrains the total synaptic weight and this seems to make the model stable. We investigate the role of the constraint and show that it is the constraint that makes the model stable. For analyzing this setting, we propose a simple probabilistic game that models the neural network and the self-organization process. Then, we investigate the characteristics of this game, namely, the probability that the game becomes stable and the number of the steps it takes.Comment: To appear in the Proc. RANDOM'98, Oct. 199

Effects of wind on radiation spectra from magnetized accretion disks

The effects of a wind on the emerging spectrum from an inefficiently-radiating accretion flow in a global magnetic field are examined, based on the analytic solution obtained recently by one of the present authors. The results exhibit the steepening of the negative slope appearing in the intermediate frequency range of bremsstrahlung spectrum and the decrease in the luminosity ratio of thermal synchrotron to bremsstrahlung, in accordance with the increasing wind strength. Both effects are due to a suppressed mass accretion rate in the inner disk, caused by a mass loss in terms of wind. In order to demonstrate the reliability of this model, Sagittarius A^* (Sgr A^*) and the nucleus of M 31, both of which have been resolved in an X-ray band by Chandra, are taken up as the best candidates for the broadband spectral fittings. Although the observed X-ray data are reproduced for these objects by both of the inverse-Compton and the bremsstrahlung fittings, some evidence of preference for the latter are recognized. The wind effects are clearly seen in the latter fitting case, in which we can conclude that a widely extending accretion disk is present in each nucleus, with no or only weak wind in Sgr A^* and with a considerably strong wind in the nuclear region of M 31. Especially in Sgr A^*, the inferred mass accretion rates are much smaller than the Bondi rate whose estimate has become reliable due to Chandra. This fact strongly suggests that the accretion in this object does not proceed like Bondi's prediction, though its extent almost reaches the Bondi radius.Comment: Accepted for publication in MNRA

L-Arginine treatment may prevent tubulointerstitial nephropathy caused by germanium dioxide

L-Arginine treatment may prevent tubulointerstitial nephropathy caused by germanium dioxide.BackgroundLong-term oral ingestion of germanium dioxide (GeO2) causes progressive renal failure derived from tubulointerstitial nephropathy in humans and animals. The characteristic of GeO2-induced nephropathy is the renal tissue injury persisting for a long time, even after cessation of GeO2 ingestion. However, a treatment that can suppress the long-lasting renal tissue injury has not yet been established.MethodsUsing the methods of immunohistochemistry and reverse transcription-polymerase chain reaction, we examined the expression of ED1-positive cells (macrophages/monocytes), transforming growth factor (TGF)-β1 mRNA and protein and collagen type IV mRNA and protein in the kidneys of rats with GeO2-induced nephropathy. Concomitantly, the effects of L-arginine treatment on their expression was explored in the kidneys of rats with GeO2-induced nephropathy.ResultsChronic administration of GeO2 caused tubulointerstitial nephropathy characterized by leukocyte invasion into the enlarged tubulointerstitial space in rats. The expression of ED1-positive cells, TGF-β1 protein and collagen type IV protein was markedly increased in the tubulointerstitium of the renal cortex from rats with GeO2-induced nephropathy. Similarly, TGF-β1 and collagen type IV mRNA were significantly enhanced in the renal cortex of rats with GeO2-induced nephropathy. A small number of tubulointerstitial cells expressing TGF-β1 protein were also observed in the renal cortex of rats with GeO2-induced nephropathy. However, L-arginine treatment led to a parallel decrease in the expression of ED1-positive cells, TGF-β1 mRNA and collagen type IV mRNA and protein in rats with GeO2-induced nephropathy.ConclusionsIn general, collagen synthesis is driven by TGF-β1 in the fibrotic process associated with a variety of renal disorders. TGF-β1 is secreted by TGF-β1 producing cells such as macrophages, fibroblasts and myofibroblasts. Thus, the present study indicates that the expression of collagen type IV may be mediated by TGF-β1 released from invading macrophages and, to a lesser extent, released from tubulointerstitial cells, presumably fibroblasts and/or myofibroblasts in GeO2-induced nephropathy. L-Arginine treatment inhibits collagen type IV synthesis possibly by suppressing macrophage invasion and the resultant TGF-β1 expression in this nephropathy. L-Arginine treatment may be beneficial in the prevention of tubulointerstitial fibrosis, which is considered to be the terminal stage of GeO2-induced nephropathy

Radiation Spectra from Advection-Dominated Accretion Flows in a Global Magnetic Field

We calculate the radiation spectra from advection-dominated accretion flows (ADAFs), taking into account the effects of a global magnetic field. Calculation is based on the analytic model for magnetized ADAFs proposed by Kaburaki, where a large-scale magnetic field controls the accretion process. Adjusting a few parameters, we find that our model can well reproduce the observed spectrum of Sagittarius A$^{*}$. The result is discussed in comparison with those of well-known ADAF models, where the turbulent viscosity controls the accretion process.Comment: Accepted for publication in Ap

Pulmonary Hemodynamics and Six-Minute Walk Test Outcomes in Patients with Interstitial Lung Disease

Background. Six-minute walk test (6MWT) has 3 measurement outcomes, which are walk distance, desaturation, and symptom. The aim of this study was to examine whether routinely measured right-heart catheter (RHC) data correlate with 6MWT outcomes in patients with interstitial lung disease (ILD). Methods. Between June 2010 and December 2012, consecutive patients with ILD who underwent evaluation, including pulmonary function test, hemodynamic studies with right-heart catheter, and 6MWT as routine general practice, were recruited. Correlates of 3 outcomes of 6MWT were examined to reveal significant predictors. Results. Forty-six patients consisting of 20 with idiopathic pulmonary fibrosis, 14 with collagen vascular disease associated ILD, and 12 with other idiopathic interstitial pneumonia were recruited (mean % predicted FVC: 76.7±17.1%). Several physiological variables, including mean pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR), were correlated with each 6MWT outcome. Stepwise multivariate regression analyses showed that % predicted FVC and % predicted DLco were independent predictors of walk distance (r2=0.35, p=0.0002). For SpO2 at the end of 6MWT, % predicted DLco and PVR were selected as independent predictors (r2=0.46, p<0.0001). For dyspnea at the end of 6MWT, % predicted DLco was only one predictor (r2=0.18, p=0.005). Conclusion. Mean PAP had little impact on 6MWT outcomes in ILD patients who were nonselectively recruited, although PVR was one of predictors of desaturation

Experimental investigation of a control scheme for a tuned resonant sideband extraction interferometer for next-generation gravitational-wave detectors

LCGT plans to use tuned RSE as the optical configuration for its interferometer. A tuned RSE interferometer has five degrees of freedom that need to be controlled in order to operate a gravitational-wave detector, although it is expected to be very challenging because of the complexity of its optical configuration. A new control scheme for a tuned RSE interferometer has been developed and tested with a prototype interferometer to demonstrate successful control of the tuned RSE interferometer. The whole RSE interferometer was successfully locked with the control scheme. Here the control scheme and the current status of the experiment are presented

Ruthenium Picolinate Complex as a Redox Photosensitizer With Wide-Band Absorption

Ruthenium(II) picolinate complex, [Ru(dmb)2(pic)]+ (Ru(pic); dmb = 4,4′-dimethyl-2,2′-bipyridine; Hpic = picolinic acid) was newly synthesized as a potential redox photosensitizer with a wider wavelength range of visible-light absorption compared with [Ru(N∧N)3]2+ (N∧N = diimine ligand), which is the most widely used redox photosensitizer. Based on our investigation of its photophysical and electrochemical properties, Ru(pic) was found to display certain advantageous characteristics of wide-band absorption of visible light (λabs &lt; 670 nm) and stronger reduction ability in a one-electron reduced state (E1/2red = −1.86 V vs. Ag/AgNO3), which should function favorably in photon-absorption and electron transfer to the catalyst, respectively. Performing photocatalysis using Ru(pic) as a redox photosensitizer combined with a Re(I) catalyst reduced CO2 to CO under red-light irradiation (λex &gt; 600 nm). TONCO reached 235 and ΦCO was 8.0%. Under these conditions, [Ru(dmb)3]2+ (Ru(dmb)) is not capable of working as a redox photosensitizer because it does not absorb light at λ &gt; 560 nm. Even in irradiation conditions where both Ru(pic) and Ru(dmb) absorb light (λex &gt; 500 nm), using Ru(pic) demonstrated faster CO formation (TOFCO = 6.7 min−1) and larger TONCO (2347) than Ru(dmb) (TOFCO = 3.6 min−1; TONCO = 2100). These results indicate that Ru(pic) is a superior redox photosensitizer over a wider wavelength range of visible-light absorption

Removal of Anhydrite and Mg-Silicate Scales from Production Wells Using Chemical Agents at the Mori Geothermal Field in Hokkaido, Japan: An Application of Chemical Well Stimulation

ABSTRACT Well stimulation, which enhances permeability, is an important technique in the creation of Engineered Geothermal Systems (EGS). In addition to physical stimulation such as hydrofracturing, chemical stimulation has been used at several EGS fields. In addition to conventional mineral acids, chelating agents and alkaline solutions have been studied and employed to dissolve calcium and silica minerals without significant casing corrosion. We tested the notion that this chemical stimulation technique was applicable to the removal of anhydrite and Mg-silicate deposits as a replacement for costly mechanical workovers. We conducted two scale removal operations using chelating and alkaline agents at the Mori geothermal field. Two distinct scale minerals, anhydrite and Mg-silicate, were observed in two different production wells. The latter scale consists of crystalline and amorphous structures. We confirmed that the chelating and alkaline solutions not only dissolved anhydrite and Mg-silicate scales but caused them to spall into particles and powders in the laboratory prior to the stimulation on site. The spalled scale fragments can be readily ejected from the wellbore during production. We injected a chelating agent and alkaline solutions into the wells in July and November, 2008. Combined with successive production, the majority of scale was removed and the treated wells showed improved productivity

The MAXI Mission on the ISS: Science and Instruments for Monitoring All Sky X-Ray Images

The MAXI (Monitor of All-sky X-ray Image) mission is the first astronomical payload to be installed on the Japanese Experiment Module-Exposed Facility (JEM-EF) on the ISS. It is scheduled for launch in the middle of 2009 to monitor all-sky X-ray objects on every ISS orbit. MAXI will be more powerful than any previous X-ray All Sky Monitor (ASM) payloads, being able to monitor hundreds of AGN. MAXI will provide all sky images of X-ray sources of about 20 mCrab in the energy band of 2-30 keV from observation on one ISS orbit (90 min), about 4.5 mCrab for one day, and about 1 mCrab for one month. A final detectability of MAXI could be 0.2 mCrab for 2 year observations.Comment: 12 pages, 11 figures, accepted for publication in Publications of the Astronomical Society of Japa