Search

The observation of figure-ground selectivity in neurons of the visual cortex shows that these neurons can be influenced by the image context far beyond the classical receptive field. To clarify the nature of the context integration mechanism, we studied the latencies of neural edge signals, comparing the emergence of context-dependent definition of border ownership with the onset of local edge definition (contrast polarity; stereoscopic depth order). Single-neuron activity was recorded in areas V1 and V2 of Macaca mulatta under behaviorally induced fixation. Whereas local edge definition emerged immediately (

A recent physiological finding of neural coding for border ownership (BO) that defines the direction of a figure with respect to the border has provided a possible basis for figure-ground segregation. To explore the underlying neural mechanisms of BO, we investigated stimulus configurations that activate BO circuitry through psychophysical investigation of the BO-dependent tilt aftereffect (BO-TAE). Specifically, we examined robustness of the border ownership signal by determining whether the BO-TAE is observed when gestalt factors are broken. The results showed significant BO-TAEs even when a global shape was not explicitly given due to the ambiguity of the contour, suggesting a contour-independent mechanism for BO coding., This paper was published in Journal of the Optical Society of America. A and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=josaa-24-1-18. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

The integration of auditory and visual stimuli is crucial for recognizing objects, communicating effectively, and navigating through our complex world. Although the frontal lobes are involved in memory, communication, and language, there has been no evidence that the integration of communication information occurs at the single-cell level in the frontal lobes. Here, we show that neurons in the macaque ventrolateral prefrontal cortex (VLPFC) integrate audiovisual communication stimuli. The multisensory interactions included both enhancement and suppression of a predominantly auditory or a predominantly visual response, although multisensory suppression was the more common mode of response. The multisensory neurons were distributed across the VLPFC and within previously identified unimodal auditory and visual regions (O'Scalaidhe et al., 1997; Romanski and Goldman-Rakic, 2002). Thus, our study demonstrates, for the first time, that single prefrontal neurons integrate communication information from the auditory and visual domains, suggesting that these neurons are an important node in the cortical network responsible for communication.

An object viewed from different angles can be recognized and distinguished from similar distractors after the viewer has had experience watching it rotate. It has been assumed that as an observer watches the rotation, separate representations of individual views become associated with one another. However, we show here that once monkeys learned to discriminate individual views of objects, they were able to recognize objects across rotations up to 60 degrees , even though there had been no opportunity to learn the association between different views. Our results suggest that object recognition across small or medium changes in viewing angle depends on features common to similar views of objects.

The effect of chemical substitution on improving cycle performance of orthorhombic LiMnO 2 ( o -LiMnO 2 ) was studied at the nominal compositions of LiMn 0.95− x M x Cr 0.05 O 2 ; M=Al, Ga, Yb and In, 0.01 x 0.92 In 0.03 Cr 0.05 O 2 was confirmed as the optimum composition. The crystal structure refinement showed that chemical substitution varied the average ionic radii of cation sites in o- LiMnO 2 . The ratio of average ionic radius at Mn site to that of Li site of the optimum compound was 0.87. This value was larger than that of no-substituted LiMnO 2 ; 0.84. TEM observation revealed that stacking faults were observed in the LiMn 0.92 In 0.03 Cr 0.05 O 2 grains. It is assumed that these two factors, controlling ionic radii and introducing stacking faults, are key parameters for improving cycle performance. However X-ray diffraction data and discharge curves suggested that phase transformation from orthorhombic to cubic spinel occurred during charge–discharge cycle.

Controlling the kinetic energy of deposition species is an effective way to improve a thin film's physical properties. An apparatus that can select the kinetic energy of laser-ablated particles was developed. It was demonstrated that the energy of the laser-ablated particles was selected by chopping with the slit of a rotating disk. The energy profile of each ablated particle is illustrated, and the relationships between the selected velocity region and the selection conditions, such as disk rotation speed and delay time, are demonstrated. This apparatus was applied to the deposition of Au, Pt and Ag thin films. This process was also useful to improve surface morphology because the number of droplets on these films drastically decreased.

Controlling the kinetic energy of deposition species is an effective way to improve thin film's physical properties. An apparatus that can select the kinetic energy of laser ablated particles was developed. It was demonstrated that the energy of laser ablated particle was selected by chopping with the slit of rotating disk. This apparatus was applied to thin film deposition and it was useful to improve surface morphology because the number of droplets on the film drastically decreased.

The mode of occurrence and the origin of cracking of lithium tetraborate (Li2B4O7) during growth by CZ method have been investigated. It is considered that crystal cracking can be divided into two main modes of occurrence. Each origin of cracking have been examined; 3-inch-diameter crack-free Li2B4O7 have been successfully grown.

An apparatus with a rotating mechanical chopper for thin film production has been developed. It is demonstrated that the energy of ablated particles is well selected by this method. Further, this method is applicable to Au thin film deposition and, is recognized to be useful to improve thin film quality because the number of droplets in the film are drastically decreased.

Attention depends on figure-ground organization: figures draw attention, whereas shapes of the ground tend to be ignored. Recent research has revealed mechanisms for figure-ground organization in the visual cortex, but how these mechanisms relate to the attention process remains unclear. Here we show that the influences of figure-ground organization and volitional (top-down) attention converge in single neurons of area V2 in Macaca mulatta. Although we found assignment of border ownership for attended and for ignored figures, attentional modulation was stronger when the attended figure was located on the neuron's preferred side of border ownership. When the border between two overlapping figures was placed in the receptive field, responses depended on the side of attention, and enhancement was generally found on the neuron's preferred side of border ownership. This correlation suggests that the neural network that creates figure-ground organization also provides the interface for the top-down selection process.

The mode of occurrence and the origin of cracking of 3-inch diameter Li/sub 2/B/sub 4/O/sub 7/ single crystal during growth have been investigated. From these considerations, growth conditions for crack-free single crystal have been examined and crack-free 3-inch diameter lithium tetraborate (Li/sub 2/B/sub 4/O/sub 7/) single crystals by Czochralski method have been successfully grown. >

Gd-Ba-Cu-O films were grown on MgO(100). The film orientation depends on the substrate temperature: a-axis film from 580 to 720 °C; mix orientation (a+c) film between 720 and 780°C; c-axis film above 780 °C. The films have high crystalline quality from channeling studies and no film-substrate reaction was detected. The film surface morphologies depended not only on the substrate temperature but also the composition (Ar:O2) of the sputtering gas.

Thin films of the oxide superconductor (Y,Gd)BaCuO system on MgO(100) substrates were prepared by Facing Targets Sputtering (FTS) deposition method. These thin films possess the following properties ;Y-Ba-Cu-O(YBCO) thin film has Tc(0)=72[K], Jc(at 4.2[K])=6.2 × 106[A/cm2] ; Gd-Ba-Cu-O(GBCO) thin film has Tc(0)=58[K], Jc(at 4.2[K])=2.2 × 105[A/cm2] ; (Y,Gd)-Ba-Cu-O ((Y,G)BCO) thin fim has Tc(0)=69[K], Jc(at 4.2[K])=3.2 ×105[A/cm2]. Current-voltage characteristics of these thin films are as follows ; YBCO thin film has define hysteresis, (Y,G)BCO thin film’s critical current(Ic) drops in I-V curve with micro-wave irradiation.

Recent physiological studies revealed that neurons in the macaque visual cortex encode the direction of a figure along a contour (border ownership, BO). Although their cortical mechanisms have not been clarified, a computational model for BO has suggested that surround modulation in early vision can play an important role. Here we examined psychophysically how the strength of BO-dependent tilt aftereffect (BO-TAE) is modulated by a stimulus outside the adapted location in relation to the strength of surround modulation reported in physiological experiments. The results showed systematic change of the strength of BO-TAE, depending on the difference in orientation and spatial frequency between the bars placed outside and at the adapted location, indicating a crucial role of surround modulation in the neural mechanism underlying BO selectivity., This paper was published in Journal of the Optical Society of America. A and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=josaa-24-1-18. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

BiSrCaCuO superconducting thin films were prepared on MgO (100) substrates by metal organic chemical vapor deposition (MOCVD) using Bi(ph)3, Sr-, Ca-, Cu(DPM)2, and effects of deposition parameters (substrate temperatures (Ts), oxygen flow rates (FO2) and cooling rates (C.R)) were investigated with regards to superconducting properties of films. A film as prepared at Ts=800°C, in FO2=200ccm, and with C.R=15°C/min possesses the (2212) structure. This film shows a micro mosaic structure with c-axis orientation perpendicular to the substrate, and has zero-resistance temperature of 72K.

Mode of occurrence and cause of twinning, which are occasionally observed in lithium tetraborate crystals grown pararell to [110], have been investigated. Twinning is related to the crystal symmetry, i.e., 4-fold screw axis along the c-axis. Relashionship between the cause of striations in crystals and the occurence of twinning during growth has also been examined in connection with temperature fluctuations near the interface.

The growth of crack-free 3-inch-diameter lithium tetraborate ( Li2B4O7) single crystals by the Czochralski method has been studied. The relationships between crystal cracking rate during growth and the crystal rotation rate and the position of the work-coil have been examined. It is concluded that crystal cracking at a later stage of growth is related to the temperature fluctuation in melt.

The mode and origin of cracking of lithium tetraborate ( Li2B4O7) single crystals during growth using a resistance heating furnace have been studied. The relationship between the formation mechanism of anomalous growth ridges and the occurrence of cracking was examined. It is concluded that a high temperature gradient near the interface and small temperature fluctuations in the melt are needed for growing a crack-free 3-inch-diameter Li2B4O7 single crystal.

Thermochemical data on LnFeO3, Ln3Fe5O12, and (LnFeO3)nFeO (n = 1 and 2) which are stable in the Ln2O3FeOFe2O3 systems at elevated temperatures are reevaluated and interpreted on the basis of a simple point charge ionic model (Ln: lanthanide elements and Y). As the radius of the Ln ion in each compound decreases, the LnFeO3 compound (distorted perovskite type) becomes less stable, the Ln3Fe5O12 compound (garnet type) is the most stable for Ln = Tb, and the (LnFeO3)nFeO compounds (layered structures) become more stable. The stability of each phase is strongly dependent upon the fitting of Ln ion in A-site position for the perovskite structure, in the dodecahedral site position for the garnet structure, and in the octahedral site positions for the layered structure compounds, respectively. It is qualitatively useful to estimate the Madelung energies of a series of isostructural phases on the basis of a simple point charge ionic model, especially as a guide for understanding a series of new phase diagrams which describe the isostructural phases.

Kinetic and thermodynamic studies of the oxidation of ζ ( n = 9 in Pr n O 2 n −2 ) to epsilon ( n = 10) phase have been carried out using a thermogravimetric technique. The experiments covered a temperature range of 464 to 503°C and oxygen pressure varied from 0.01 to 50 Torr. The existence of a reproducible hysteresis loop which depends on the temperature and pressure is shown. Measurements of the oxidation rate under isothermal conditions were fitted to different rate equations and have been found to be well represented by the equation f = 1 − (1 − kt ) 3 . This fact indicated that the process of oxidation was predominantly controlled by the chemical reaction at the interface. The activation energy for the reaction has been calculated to be 15.9 kcal/mole.

Magnetic properties and electrical conductivity were measured on polycrystalline Lu 2 Fe 3 O 7 from 4.2 K to 650 K and were compared with those of LuFe 2 O 4 . The electrical conductivity, the magnetic susceptibility per Fe at low temperatures and the induced moment per formula unit are nearly the same for both materials. It is concluded that Lu 2 Fe 3 O 7 is constructed by an alternate stacking of Lu 3+ Fe 2 2.5+ O 4 and Lu 3+ Fe 3+ O 3 and that the magnetic moment is induced by the field cooling mainly in the former part. The origin of the moment induction (parasitic ferrimagnetism) is discussed briefly.

Phase equilibria in the Ce-O system at 1000, 1100, 1153, 1200, 1249, 1310, and 1330°C and those in the Ce-Fe-O system at 1000, 1100, and 1200°C were established. The former system has CeO2 with a fluorite type, Ce3O5 with a C-type rare-earth oxide, and Ce2O3 with a A-type rare-earth oxide. CeO2 and Ce3O5 have nonstoichiometric compositions, but the stoichiometry of Ce2O3 was confirmed at 1200, 1249, and 1310°C. In the latter system, only the one ternary compound CeFeO3 was confirmed under present experimental conditions. On the basis of the established phase diagrams, the standard Gibbs energies of the reactions: (1) 3/2 Ce2O3 + 1/4 O2 = Ce3O5, (2) 1/3 Ce3O5 + 1/6 O2 = CeO2, (3) 1/3 Fe3O4 + CeO2 = CeFeO3 + 1/6 O2, and (4) Fe + CeO2 + 1/2 O2 = CeFeO3, were determined at various temperatures. Also relationships between ΔG° and the temperatures of the same reactions were determined within the experimental temperature range.

After establishing the phase equilibria in the systems FeFe2O3Ho2O3 and FeFe2O3Tm2O3 at 1150, 1200, and 1250°C, the standard Gibbs free energies of formation of HoFe2O4, Ho3Fe5O12, HoFeO3, TmFe2O4, Tm3Fe5O12, TmFeO3 have been determined on the basis of reactions among metallic iron, oxygen, and the respective lanthanoid sesquioxide. A new compound Tm2Fe3O7 was found at 1380°C. The standard Gibbs free energies of formation of Gd3Fe5O12, Tb3Fe5O12, and Dy3Fe5O12 were also determined. On the basis of these new data together with our previous studies on phase equilibria in the FeFe2O3lanthanoid sesquioxide systems, we have been able to establish a phase diagram at high temperatures from 900 to 1400°C. The thermochemical relative stability in each type of compound, that is to say, LnFeO3 (Ln = La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y), Ln3Fe5O12 (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y), LnFe2O4 (Ln = Ho, Er, Tm, Yb, Lu, and Y), and Ln2Fe3O7 (Ln = Yb and Lu) was investigated by using the following standard Gibbs free energy changes of oxide-oxide reactions, 1 2 Fe 2 O 3 + 1 2 Ln 2 O 3 = Ln FeO 3 , 3Ln FeO 3 + Fe 2 O 3 = Ln 3 Fe 5 O 12 , FeO + Ln FeO 3 = Ln Fe 2 O 4 , and LnFe2O4 + LnFeO3 = Ln2Fe3O7. The results thus obtaine were compared with those of the structural relative stability.

The standard Gibbs energies of the reaction of EuFeO3 and Fu3Fe5O12 were determined to be −63300±200 cal and −297800±600 cal respectively at 1200°C by means of following reactions: Fe+1/2 Eu2O3+3/4 O2=EuFeO3 and 5 Fe+3/2 Eu2O3+15/4 O2=Eu3Fe5O12, based on the phase equilibria in the Fe–Fe2O3–Eu2O3 system.

The standard Gibbs energy of formation of \barCFeO3(\barC=La, Nd, Sm, Eu, Gd, Tb, and Dy) from metallic iron, \barC2O3, and oxygen has been determined at temperatures from 1473 to 1673 K. Based on the free-energy data, the heat of reaction and the entropy change resulting from the reaction have been calculated. The values of the heat of reaction of LaFeO3, NdFeO3, SmFeO3, EuFeO3, and GdFeO3 (the first group) were identical, −107 kcal/mol, at the present temperature interval. However, the values of the heat of reaction of TbFeO3 and DyFeO3 (the second group) decreased with an increase in the temperature. The entropy change of each reaction in the first group was constant, independent of the temperature, and each value decreased in the sequence from LaFeO3 to GdFeO3. The entropy change of the second group decreased with an increase in the temperature. The change of the standard Gibbs energy was intimately related to the ionic radii of \barC-ions, and the relationship between the Gibbs energy and the toleran...

The standard Gibbs energies of the reaction of EuFeO3 and Fu3Fe5O12 were determined to be −63300±200 cal and −297800±600 cal respectively at 1200°C by means of following reactions: Fe+1/2 Eu2O3+3/4 O2=EuFeO3 and 5 Fe+3/2 Eu2O3+15/4 O2=Eu3Fe5O12, based on the phase equilibria in the Fe–Fe2O3–Eu2O3 system.

The standard Gibbs energy of formation of \barCFeO3(\barC=La, Nd, Sm, Eu, Gd, Tb, and Dy) from metallic iron, \barC2O3, and oxygen has been determined at temperatures from 1473 to 1673 K. Based on the free-energy data, the heat of reaction and the entropy change resulting from the reaction have been calculated. The values of the heat of reaction of LaFeO3, NdFeO3, SmFeO3, EuFeO3, and GdFeO3 (the first group) were identical, −107 kcal/mol, at the present temperature interval. However, the values of the heat of reaction of TbFeO3 and DyFeO3 (the second group) decreased with an increase in the temperature. The entropy change of each reaction in the first group was constant, independent of the temperature, and each value decreased in the sequence from LaFeO3 to GdFeO3. The entropy change of the second group decreased with an increase in the temperature. The change of the standard Gibbs energy was intimately related to the ionic radii of \barC-ions, and the relationship between the Gibbs energy and the toleran...

Thermodynamic studies of phase transformations between the intermediate phases (PrnO2n−2) reveal reproducible hysteresis loops. In this report, kinetic studies between the zeta (n = 9) and the epsilon (n = 10) phases have been carried out by measuring the weight change of the sample as a function of time after a sudden increase of oxygen pressure. The experiments covered temperatures of 464, 477, 491 and 503°C and oxygen pressure varied from 0.01 to 50 Torr.

Magnetic and Mossbauer measurements were done between 77 and 300 K on polycrystalline sample of YFe 2 O 4 (Y 3+ Fe 2+ Fe 3+ O 4 2- ). This compound shows an “induced parastic ferromagnetism”: Weak ferromagnetic moment (∼2 emu/g) was induced below 240 K by applying external field (∼7 kOe) and an uniaxial anisotropy was induced by cooling the sample from 300 K to 77 K in the presence of external field. Mossbauer spectrum of Fe 57 showed a magnetic pattern with internal field of ca. 460 kOe at 90 K, and showed a paramagnetic one at 300 K.

Phase equilibria in FeFe 2 O 3 Cr 2 O 3 , FeFe 2 O 3 V 2 O 3 , FeOFe 2 MoO 4 Fe 3 O 4 , and FeOFe 2 O 3 ZrO 2 systems were precisely determined. On the basis of the present results, together with the FeOFe 2 O 3 TiO 2 system studied by Taylor at 1300°C and by Webster and Bright at 1200°C, the following results were obtained. (1) The solid solutions Fe 2 TiO 4 Fe 3 O 4 , and Fe 2 MoO 4 Fe 3 O 4 are approximately ideal in respect to the activity-composition relation. (2) On the contrary, the solid solutions FeCr 2 O 4 Fe 3 O 4 and FeV 2 O 4 Fe 3 O 4 deviate significantly from Raoult's law, and these are of regular solution defined by Hildebrand.