Transcellular retrograde labeling of radial glial cells with WGA-HRP and DiI in neonatal rat and hamster

Topographically distinct populations of radial glial cells in the diencephalon and mesencephalon of neonatal rats and hamsters were transcellularly labeled with wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) and with the lipophilic tracer DiI. A comparison of the histological distribution of the two tracers is suggestive of two different mechanisms of transcellular labeling. Intraocular injections of WGA-HRP resulted in the uptake of exogenously applied WGA-HRP by retinal ganglion cells, followed by anterograde axonal transport and exocytosis within the optic target nuclei. In addition to the transneuronal labeling, which is typical of such injections, we observed the transcellular labeling of the processes and somata of radial glial cells that were topographically associated with the terminal fields of the labeled axons. Similar transcellular labeling of radial glial cells associated with the axon terminal fields of the colliculogeniculate projection to the medial geniculate nucleus was observed following injections of WGA-HRP in the inferior colliculus. The transcellular labeling within the radial glial cells was discontinuous and somatopetally concentrated, indicating the existence of a retrograde active transport mechanism within the radial glial processes subsequent to its uptake following release of tracer from axons. This type of labeling can be referred to as transcellular retrograde glioplasmic transport. In contrast, DiI was used as a tracer through its capacity to diffuse within the plasmalemma. Topographically distinct populations of radial glial cells were transcellularly labeled following placements of DiI in the retina, inferior colliculus, or dorsal thalamus of fixed brains. The radial processes of labeled radial glial cells consistently extended into regions that also contained labeled axons. It is likely that the transcellular radial glial labeling with DiI occurred via transmembranous diffusion. These data indicate that a close structural and functional relation exists between axons and glial cells in the developing brain.     

A novel technique for a DC brushless motor without position sensors

A dc brushless motor is a kind of synchronous motor driven by an inverter and requires sensors to detect the rotor position. As one of the methods, the induced voltages of a brushless motor have been utilized in practice. However, there are some problems in this method, e.g., the motor can obtain insufficient torque due to the low induced voltages in a low-speed range. This paper proposes a new method which controls the inverter angular frequency ω₁ by using inherent characteristics wherein the torque current i_r is almost proportional to the internal phase angle φ where the primary flux of a synchronous motor is controlled to be constant. If the parameters of a motor are given exactly, the speed regulation is quite small and the transient characteristics with high response and high starting torque are obtained. Furthermore, it is possible to operate a synchronous motor in the field-weakening range. Here, the principle of the control method and the performance characteristics of a dc brushless motor having no position sensors are discussed. The simulation and the experimental results of the tested machine show that the proposed method is very useful for practical applications.     

Path tracking control of Lagrange systems with obstacle avoidance

This paper addresses a path tracking problem with obstacle avoidance for Lagrange systems. The proposed method is based on field potential methods in combination with navigation functions for obstacle avoidance. First, it is shown that a simple combination of the navigation function with the conventional path tracking controller does not work. Therefore, in order to cope with this problem, a new feedback law is proposed for a path parameter which characterizes the reference path. It is proved that the proposed controller achieves both path following and collision avoidance. Moreover, since the method adopts bounded navigation functions, the proposed controllers generate bounded input signals even when target systems approach obstacles. Finally, an experimental evaluation is performed with a two-link manipulator to illustrate the effectiveness of the proposed method.     

Drawing plane graphs nicely

Summary This paper presents two efficient algorithms for drawing plane graphs nicely. Both draw all edges of a graph as straight line segments without crossing lines. The first draws a plane graph convex if possible, that is, in a way that every inner face and the complement of the outer face are convex polygons. The second, using the first, produces a pleasing drawing of a given plane graph that satisfies the following property as far as possible: the complements of 3-connected components, together with inner faces and the complement of the outer face, are convex polygons. The running time and storage space of both algorithms are linear in the number of vertices of the graph.     

Making exhaustive search programs deterministic

This paper presents a technique for compiling a Horn-clause program intended for exhaustive search into a GHC (Guarded Horn Clauses) program. The technique can be viewed also as a transformation technique for Prolog programs which compiles away the ‘bagof’ primitive and non-determinate bindings. The class of programs to which our technique is applicable is shown with a static checking algorithm; it is nontrivial and could be extended. An experiment on a compiler-based Prolog system showed that our technique improved the efficiency of exhaustive search by 6 times for a permutation generator program. This compilation technique is important also in that it exploits the AND-parallelism of GHC for parallel search.     

Application of enzymatically gelled chitosan solutions to water‐resistant adhesives

An investigation was undertaken on the application of dilute chitosan solutions gelled by tyrosinase‐catalyzed reaction with 3,4‐dihydroxyphenethylamine (dopamine). The tyrosinase‐catalyzed reaction with dopamine conferred water‐resistant adhesive properties to the semidilute chitosan solutions. The viscosity of the chitosan solutions increased highly by the tyrosinase‐catalyzed reaction and the subsequent reactions between o‐quinone compounds and chitosan. These highly viscous, gel‐like modified chitosan materials were allowed to spread onto the surfaces of the glass slides, which were tightly lapped together and held them in water. Tensile shear adhesive strength of over 400 kPa was observed for the modified chitosan samples. The increase in the amino group concentration of the chitosan solutions and the molecular mass of the chitosan used effectively led to the increase in adhesive strength of the glass slides. In addition, in the case where the chitosan solution was gelled by the enzymatic reaction with dopamine in the presence of poly(ethylene glycol), adhesive strength sharply increased at shorter reaction times concomitantly with the increase in the viscosity of the chitosan solutions because the tyrosinase activity effectively was retained by poly(ethylene glycol). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1818–1827, 2007     

Photocatalysts using hexa- and octa-titanates with different tunnel space for water decomposition

Photocatalytic activities for water decomposition were examined for photocatalysts using hexa- and octa-titanates and TiO2(B) with different tunnel space in the structure. Using RuO2 as promoter, M2Ti6O13 (M = Li, Na, K, Rb) showed the stoichiometric production of Hz and O₂ except for Li, whereas H₂Ti₈O₁₇ and TiO₂(B) had very low activity producing only hydrogen as a product. The effects of promoters on Na₂Ti₆O₁₃ showed that the activity increased in the order of RuO₂ > RuO₂ + IrO₂ > IrO₂ > RuO₂ + Pt > MnO₂. These effects along with other related ones are discussed: it emerges that the presence of the tunnels is important for the achievement of high photocatalytic activity.     

Crystal Structure and Microwave dielectric Properties of Ba(Zn1/3Ta2/3)O3–(Sr,Ba)(Ga1/2Ta1/2)O3 Ceramics

The microwave dielectric properties and crystal structure of Ba(Zn_1/3Ta_2/3)O₃– (Sr,Ba)(Ga_1/2Ta_1/2)O₃ ceramics were investigated in the present study. The Q value of Ba(Zn_1/3Ta_2/3)O₃ was improved by adding 5 mol% Sr(Ga_1/2Ta_1/2)O₃. The maximum Q value of Q × f = 162000 GHz was obtained at 0.95Ba(Zn_1/3Ta_2/3)O₃. 0.05Sr(Ga_1/2Ta_1/2)O₃. For this composition, a lattice super structure caused by hexagonal ordering was observed. A further improvement in the Q value was attained when some Sr was replaced with Ba, and 0.95Ba(Zn_1/3Ta_2/3)O₃· 0.05(Sr_0.25Ba_0.75)(Ga_1/2Ta_1/2)O₃ exhibited a maximum Q value such that Q × f = 210000 GHz. Despite the increased Q value with the replacement of Sr by Ba, the c/a value, which indicates the degree of lattice distortion, remained constant near 3/2. The Q value thus improved without lattice distortion in the system Ba(Zn_1/3Ta_2/3)O₃-(Sr,Ba)(Ga_1/2Ta_1/2)O₃, whereas the improvement of Q value increased with lattice distortion in the solid solution system with Ba(Zn_1/3Ta_2/3)O₃ as an end member.     

Adsorption and desorption properties of cationic polyethylene film gels to organic anions and their regeneration

An investigation was undertaken on the adsorption and desorption properties of 2‐(dimethylamino)ethyl methacrylate grafted polyethylene (PE‐g‐PDMAEMA) films to anionic dye anions with one to three sulfonic groups in response to pH and temperature changes. The amounts of dye anions adsorbed on the PE‐g‐PDMAEMA films passed through the maximum values at about pH 3 because of an increase in the protonation of dimethylamino groups caused by a decrease in the pH value. The amounts of adsorbed dye anions decreased below pH 3 because the ionic strength increased with the addition of HCl to adjust the initial pH values of the aqueous dye solutions. The amounts of adsorbed dye anions decreased with an increase in the number of sulfonic groups in the dye molecules at the same pH value because electrostatic repulsion was generated between free sulfonic groups of the dye anions adsorbed onto the PE‐g‐PDMAEMA films and free dye anions in the medium. A large number of dye anions adsorbed were desorbed from the PE‐g‐PDMAEMA film with initial pH values above 11.0. The cyclic processes of adsorption at pH 3.0 and desorption at pH 11.0 were repeated without considerable fatigue. The PE‐g‐PDMAEMA films showed practically regenerative adsorption and desorption behavior in response to the pH changes. In addition, when the dye‐anion‐adsorbed PE‐g‐PDMAEMA films were alternately immersed in water at two different temperatures, dye anions were desorbed in water at higher temperatures without any chemical agents because of the deprotonation of dimethylamino groups and thermosensitive contraction of grafted PDMAEMA chains. These results indicate that PE‐g‐PDMAEMA films can be applied as regenerative ion‐exchange membranes for adsorption and desorption processes of anionic compounds in response to the pH and temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 381–391, 2006