Local deposition distributions of inhaled radionuclides in the human tracheobronchial tree

There is experimental evidence that bronchogenic carcinomas originate mainly at the carinal ridges of the large central airways, where primary hot spots of deposition have been found. However, current lung dosimetry models do not take into consideration the inhomogeneity of deposition within the airways. In this study, computed local distributions of deposited inhaled radionuclides such as radon progenies in morphologically realistic human airway bifurcation models are analysed for different flow rates and particle sizes. Then, local deposition enhancement factors, defined as the ratio of local to average deposition densities, are computed by scanning along the surface of the bifurcation with pre-specified surface area elements. Computed enhancement factors indicate that cells located at carinal ridges or at the inner sides of the progeny branches may receive localised doses which are two orders of magnitude higher than the average values.     

Computer simulation of dislocation core structure of metastable 111 dislocations in NiAl

The atomic structure of dislocation cores of 111 dislocations in NiAl was simulated using embedded atom method potentials and molecular statics computer simulation. In agreement with previous simulation work and experimental observations, the complete 111 dislocation is stable with respect to the two superpartials of 111 separated by an antiphase boundary. The structure of the latter configuration, though metastable, is of interest in the search for ways of improving ductility in this material. The structure of the complete dislocation and that of the metastable superpartials was studied using atomistic computer simulation. An improved visualization method was used for the representation of the resulting structures. The structure of the partials is different from that typical of 111 dislocations in b.c.c. materials and that reported previously for the B2 structure using model pair potentials.     

Phosphorus implantation in titanium: application to calibration analysis

The aim of this work is to describe some comparative analyses of implanted phosphorus in titanium by using different techniques: secondary ion mass spectroscopy, glow discharge optical spectroscopy and electron spectroscopy for chemical analysis-X-ray photoelectron spectroscopy. The amount of phosphorus was measured vs. depth. Mathematical simulation of the implantation process permitted the adoption of absolute units for concentration calibration. The use of these samples as standards for nuclear analysis is discussed. The main purpose of this use is to study phosphorus incorporation in titanium oxides prepared in phosphoric baths.     

John Carroll's The Nurnberg Funnel and minimalist documentation

In The Nurnberg Funnel, J.M. Carroll (1990) reviews and reformulates his research on minimalism, a well-known approach to both print and online software documentation in which explicit instruction is severely reduced and users learn through a predominantly exploratory process. The authors examine the book and conclude that although it is stimulating and valuable, Carroll fails to make a compelling case of minimalism as a broadly applicable alternative to the contemporary multicomponent documentation set     

Mapping the dimensionality, density and topology of data: the growing adaptive neural gas

Self-organized maps are commonly applied for tasks of cluster analysis, vector quantization or interpolation. The artificial neural network model introduced in this paper is a hybrid model of the growing neural gas model introduced by Fritzke (Fritzke, in Advances in Neural Information Processing Systems 7, MIT Press, Cambridge MA, 1995) and the adaptive resolution clustering modification for self-organized maps proposed by Firenze (Firenze et al., in International Conference on Artificial Neural Networks, Springer-Verlag, London, 1994). The hybrid model is capable of mapping the distribution, dimensionality and topology of the input data. It has a local performance measure that enables the network to terminate growing in areas of the input space that is mapped by units reaching a performance goal. Therefore the network can accurately map clusters of data appearing on different scales of density. The capabilities of the algorithm are tested using simulated datasets with similar spatial spread but different local density distributions, and a simulated multivariate MR dataset of an anatomical human brain phantom with mild multiple sclerosis lesions. These tests demonstrate the advantages of the model compared to the growing neural gas algorithm when adaptive mapping of areas with low sample density is desirable.     

Photogrammetric comparison of two methods for synchronous repair of bilateral cleft lip and nasal deformity

The principle of synchronous repair of bilateral complete cleft lip and nasal deformity is established, and the techniques are evolving. We undertook photogrammetric comparison of the method described by Mulliken (group I, n = 15) and that described by Trott (group II, n = 10). Facial proportions and angles were measured on preoperative and postoperative photographs using defined anthropometric points. The following criteria were quantified for each test group: nasolabial angle, nasal tip angle and projection, nasal width, columellar length and width, and philtral width. All parameters in both groups were compared against each other and against normal age-matched values. Results were analyzed by t test. The nasolabial angle, nasal tip angle, and nasal width were abnormally wide for both techniques (p < 0.01 for both), and there was no difference between them. Nasal tip projection was greater than normal in both techniques (p < 0.01); group I had significantly greater projection than group II (p = 0.02). Columellar length as a proportion of nasal tip protrusion approached normal in group I but was significantly shorter than normal in group II (p < 0.001). Columellar width, as a proportion of nasal width, was normal for both groups. Philtral width, in proportion to nasal width, was normal in group I and abnormally high in group II (p < 0.001). This difference was significant between the two groups (p < 0.001). In a separate cohort of 10 group I patients, the nasolabial angle was measured on lateral photographs taken 1 year post-repair and at intervals to late childhood and adolescence. Nasolabial angle changed with age from obtuse to normal in 7 of 10 patients followed to 9 years of age and in 5 of 6 patients followed until age 15 years. Columellar and upper labial inclination to the vertical were measured in 7 of these patients at 3 to 4 years and again at 13 to 15 years. There was an increase in inclination of both columella and the upper lip, between the ages of 3 to 4 and 13 to 15 years, reflecting improved lip support and growth of septum and lateral cartilages.     

News

This section ofScientometrics will carry fresh and reliable news of people, programs, recent and forthcoming meetings and publications, etc. Its effectiveness depends greatly on your assistance. Items for inclusion should be submitted to the Coordinating Editor, Dr. J.Farkas With the assistance ofJ. Balázs, Library of the Hungarian Academy of Sciences, 1361 Budapest, Roosevelt tér 9 (Hungary).     

News

This section ofScientometrics will carry fresh and reliable news of people, programs, recent and forthcoming meetings and publications etc. Its effectiveness depends greatly on your assistance. Items for inclusion should be submitted to the Co-ordinating Editor, Dr.J. Farkas.With the assistance ofJ. Balázs, Library of the Hungarian Academy of Sciences, 1361 Budapest, Roosevelt tér 9 (Hungary).     

Pulsed dye amplification and frequency doubling of singlelongitudinal mode semiconductor lasers

A single-longitudinal-mode CW AlGaAs semiconductor laser (786 nm) has been pulse-amplified in a Nd:YAG-pumped dye system by 80 dB, yielding 4-ns (FWHM) infrared pulses having energies of 1.2 mJ. These amplified pulses have then been frequency-doubled in a KDP crystal to yield 110 μJ of tunable ultraviolet radiation at 393 nm. The amplified diode laser linewidth at 786 nm is measured to be 118 MHz