Showing papers by "The Chinese University of Hong Kong published in 1970"

Nuclear behavior in the basidiomycete, volvariella volvacea

Abstract: A B S T R A C T The basidiospores of the straw mushroom are typically uninucleate and its vegetative hyphae are generally multinucleate. There is a marked reduction of nuclear number in the trama and subhymenium. Interphase nuclei exist in two forms, each of which undertakes a particular mode of division. The "diffused" nuclei divide by conventional mitosis while the "constricted" ones divide amitotically. In metaphase of mitosis nine chromosomes were seen both in polar and lateral view. This haploid number confirms the nine bivalents found in basidia during meiosis. A unique characteristic of this fungus is that the diploid nucleus, the two postkaryotic nuclei and the four postkaryotic nuclei may be enclosed by a well-defined nuclear envelope during division. VOLVARIELLA VOLVACEA (Bull. ex. Fr.) Sing., commonly known as the edible straw mushroom, has long been used as a high-priced, delicious food in China and southeastern Asia countries. Jalavicharana (1950), Go (1959), Singer (1961), Hashioka (1962), and Chang (1965a) worked on cultivation methods for different localities while Singer (1961), Liu (1964) and Chang (1965b) contributed to the morphological aspects of this fungus. It was noted by Sass (1929) that cytological consideration is important in the determination of sexuality in fungi. Since 1967 an intensive cytological study of the straw mushroom has been carried on in this laboratory in a search for more complete knowledge of its life cycle and hence its use in genetic research. The results of investigations on the nuclear behavior in basidia and basidiospores, germination in the two kinds of spores, and translocation of nuclei through septa in this fungus have been recently reported (Chang, 1969; Chang and Chu, in press). The present paper is concerned with the nuclear phenomena in hyphal cells, especially asexual nuclear division, and additional information on meiosis in basidia.

Generalised principle of operation of 3-phase thyristor invertor

Abstract: The paper explains the principle of operation of a 3-phase invertor by means of vector diagrams Commutation at fixed and variable frequencies is discussed, as well as improving the commutation by the use of diodes.

Reaction of Isocyanates and Isothiocyanates with Butyraldazine; Formation of 1‐Substituted 2‐Pyrazolines

Abstract: Phenyl isothiocyanate reacts with butyraldazine in presence of acidic catalysts to form a 2-pyrazoline (IV) whereas phenyl or benzyl isocyanates under similar conditions yield a mixture of the two isomeric 2-pyrazolines XIa and XII. On reaction with Ac2O, IV gave the 1-acetyl derivative V. Reduction with LiAlH4 led to the corresponding pyrazolidines. Reexamination of Kost's three step preparation of a 1-phenylthiocarbamoyl 2-pyrazoline [19] such as X via formic acid cyclization [18] of butyraldazine revealed that his first step product was apparently a mixture of two stereoisomeric 1-formyl-2-pyrazolines VIIIa and VIIIb. A mechanism for the formation of these pyrazolines is proposed.

The radiation field of the short backfire antenna

Abstract: The mathematical expressions for the far-field radiation pattern are derived for a short backfire antenna. By assuming that the plane conductors in the antenna are infinite in extent, a multiple image system is established as a first approximation in the derivation. Some calculated patterns are presented to illustrate the derived results and compare with the experimental E- and H- patterns given by Ehrenspeck in his work.

Managing Our Patients with Acute Primary Angle Closure: Are there Better Alternatives?

Abstract: Acute primary angle closure (APAC) remains an important disease in many parts of Asia, resulting in considerable morbidity and even irreversible blindness. The three main challenges in the management of APAC are to: • reduce intraocular pressure (IOP), and thus the symptoms, swiftly and safely • prevent recurrence of APAC • prevent progression to primary angle closure glaucoma (PACG). Traditionally, IOP reduction has largely been achieved by both topical and systemic IOP-lowering drugs (stage 1 treatment), while the preventions of recurrence of APAC and progression to PACG have been partially achieved by laser peripheral iridotomy (stage 2 treatment). Recent evidence suggested that with this traditional approach, it may take more than 2 hours to achieve IOP control and symptomatic relief.1 Furthermore, up to 58% of Asian patients may progress to the chronic form of the disease.2 In view of these inadequacies, there has been a continuous search for more effective alternative treatments for APAC. Anterior chamber paracentesis has been proposed as one possible alternative to drugs as stage 1 treatment for APAC. Lam et al described the successful application of immediate paracentesis as stage 1 treatment in a pilot series of 10 patients with APAC.3 In this issue of Asian Journal of Ophthalmology, Artini et al describe their use of paracentesis in a larger series of 45 patients with APAC.4 In addition to these published studies, Dr Paul Palmberg in Miami, USA, has also described his successful use of this technique in patients with APAC at several major international conferences (Palmberg P; 2011; personal communications). Different techniques of paracentesis have been described. Lam et al3 and Palmberg performed their paracenteses at the slit lamp in the clinic, while Artini et al4 performed paracentesis under an operating microscope with the patient supine. Lam et al3 advocated Managing Our Patients with Acute Primary Angle Closure: Are there Better Alternatives?

A Short Proof of Schaefer's Theorem

Abstract: As well-known, the preceding result is a generalization of Krein's theorem (see [1, p. 218]) to the ease of ordered locally convex spaces. Unfortunately his proof, as given El, p. 219] is based on Krein's theorem. In this note we give another proof which avoids Krein's result. Before proving this result, we require the following terminology and recall some well-known facts. Let (E, Z) be a locally convex space with a positive cone C. A subset A of E is said to be C-saturated if A = ( A + C ) c ~ ( A C ) . C is said to be normal with respect to ~ if ~ admits a neighbourhood-base of 0 consisting of C-saturated, convex, and circled sets in E. C' is called a strict C-cone if the family {A n C' A n C' : A e C} is a fundamental subfamily of C (for definition see [1, p. 79]). If W is an absorbing subset of E, Pw denotes always the gauge of W, co(W) (resp. F(W)) denotes the convex hull (resp. convex, circled hull) of IV, and W ° denotes the polar of W in E'; namely W ° = { f ~ E' : f (x) < 1 for all x in W}. Let W and U be convex ~-neighbourhoods of 0. According to the Hahn-Banach theorem, we have

Calculation of the electric field and the capacitance of a charged spherical bowl by means of toroidal co-ordinates

Abstract: Mathematical expressions for the potential function and the electric capacitance of a charged spherical bowl with respect to infinity are derived. Some numerical calculations of the potential field are presented for a charged spherical bowl of different openings and for the limiting case of a circular disc to illustrate the derived results. The mathematical expressions derived for the charged density on the concave and the convex sides of the spherical bowl are identical to those given by Kelvin, who employed the method of inversion.