Cellular Automata and Urban Form: A Primer

Artificial processes for locating urban activities based on simple rules pertaining to local circumstances give rise to complex global patterns that mirror the spatial organization of cities. These systems are called Cellular Automata (CA). They provide a useful means of articulating the way highly decentralized decision-making can be employed in simulating and designing robust urban forms. CA can be easily programmed in a variety of software, and as such provide a suggestive way of exploring actual as well as optimal patterns and plans. This primer provides a pedagogic guide to these ideas and to potential computer applications.     

Internal biasing by δ-doping for low-voltage, high-bandwidthquantum-well optical modulators

Optical intensity modulators must exhibit low-voltage operation, low insertion loss, high contrast ratio and high electrical bandwidth. Electroabsorption calculations for semiconductor quantum wells predict that internal biasing by strategic δ-doping can produce greatly improved low-voltage operation in waveguide or normal-incidence modulators, for a specified insertion loss and contrast ratio, without compromising electrical bandwidth. Growth of strategically δ-doped electrorefractive intensity modulators is shown computationally to be insensitive to nonreproducibility in layer growth. Internal biasing by strategic doping is of potential value across the whole range of modulator applications     

Analytical multipoint moment matching reduction of distributed thermal networks

In this paper, the multipoint moment matching method for model order reduction of discretized linear thermal networks is extended to distributed linear thermal networks. As a result, from the analytical canonical forms of distributed linear thermal networks, reduced thermal networks are derived analytically. This direct construction of the reduced network, from the exact analytical solutions, avoids the inevitable inaccuracies inherent in conventional surface and volume meshing. It allows nearly exact reduced thermal network construction by domain decomposition for arbitrarily complicated structures.     

The Role of α1-Adrenoceptor Antagonists in the Treatment of Prostate and Other Cancers

This review evaluates the role of α-adrenoceptor antagonists as a potential treatment of prostate cancer (PCa). Cochrane, Google Scholar and Pubmed were accessed to retrieve sixty-two articles for analysis. In vitro studies demonstrate that doxazosin, prazosin and terazosin (quinazoline α-antagonists) induce apoptosis, decrease cell growth, and proliferation in PC-3, LNCaP and DU-145 cell lines. Similarly, the piperazine based naftopidil induced cell cycle arrest and death in LNCaP-E9 cell lines. In contrast, sulphonamide based tamsulosin did not exhibit these effects. In vivo data was consistent with in vitro findings as the quinazoline based α-antagonists prevented angiogenesis and decreased tumour mass in mice models of PCa. Mechanistically the cytotoxic and antitumor effects of the α-antagonists appear largely independent of α 1-blockade. The proposed targets include: VEGF, EGFR, HER2/Neu, caspase 8/3, topoisomerase 1 and other mitochondrial apoptotic inducing factors. These cytotoxic effects could not be evaluated in human studies as prospective trial data is lacking. However, retrospective studies show a decreased incidence of PCa in males exposed to α-antagonists. As human data evaluating the use of α-antagonists as treatments are lacking; well designed, prospective clinical trials are needed to conclusively demonstrate the anticancer properties of quinazoline based α-antagonists in PCa and other cancers.     

Aspects of the kinetics of the radiation-induced polymerization of acrylonitrile in dimethylformamide

The radiation-induced homopolymerization of acrylonitrile (AN) in dimethylformamide (DMF) has been followed in detail over a range of monomer concentrations. In all cases a short induction period was observed which was equivalent to 1.6 × 10⁴ rad. The initial rates of polymerization for solutions of AN in DMF of mole fraction (×) of 0.33, 0.20, and 0.10 are 1.44 × 10^?5, 7.23 × 10^?6, and 2.79 × 10^?6 mole/dm³rad, respectively. Deviations of the polymerization pathway from the standard unity in monomer dependence are examined in terms of radical production ratios to the monomer and the solvent (Φ_M/Φ_S) and the polymer together with the solvent (Φ_p/Φ_s), for various mole fractions of AN in DMF. Thus, an indirect route to G_radical(events) is provided together with the corresponding k/k_t values.     

Quasiequilibrium treatment of gas-solid reactions. III. Rate of volatilization of tungsten by high-temperature oxidation

Theoretical predictions computed on the basis of the quasiequilibrium treatment of gas-solid reactions are compared with existing experimental data on the rate of volatilization (erosion) of solid tungsten by reaction with gaseous O₂ at high temperature ( 1300° T 3600° K) and low pressure (4.5 × 10^–7 11.5 Torr). The only unknown parameter in the analysis is the equilibrium probability, , defined as the fraction of the impinging O₂ molecules that attain thermochemical equilibrium at the tungsten surface rather than undergoing nonreactive scattering (e.g., reflection). An approximate expression for is estimated by a straightforward empirical procedure that is consistent with the quasiequilibrium treatment. The theoretical results based on this expression for T because appears to be an exponential function ofT; (b) In the intermediate region, the formation of volatile oxides decreases sharply with increasingT because atomic oxygen becomes the thermodynamically favored reaction product, thereby causing _W to decrease with increasingT; (c) In the highest region, _W again increases withT as a result of the formation of WO and the sublimation of W.This work was supported by the Joint Services Electronics Program [Contract DA28-043-AMC-02536(E)] and by NASA [Grant NGR-22-009-091].     

Abstract Stimuli Associated With Threat Through Conditioning Cannot Be Detected Preattentively.

Studies of anxiety suggest that threat stimuli can be identified preattentively, but this conclusion is questionable because of possible low-level perceptual confounds. Two experiments used visual search tasks in which abstract shapes were conditioned to carry neutral or negative valence. Experiment 1 found generally faster responses to threat-associated abstract stimuli but no evidence that they were detected preattentively, irrespective of trait anxiety level. A similar pattern was found in Experiment 2, in which individuals high in snake or spider fear showed no evidence of preattentive detection of abstract stimuli associated with their feared object. In contrast, implicit behavioral measures showed significant effects of conditioning, demonstrating that targets associated with threat were negatively evaluated in these experiments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improvement options for a former water-driven-mill building now used as a theatre

After investigating the financial feasibility (and so abandoning the idea) of providing self-generated electricity using hydro-power, it was recommended that the top priority should be the direct connection of an electricity supply, from the mains grid to the building; this would cost £8800. Thereby, the theatre would receive a relatively unrestricted supply of electricity at cheaper unit tariffs. This improvement should be followed by the most urgent repairs being carried out to the building fabric, at an estimated cost of £6990. These repairs are necessary to ensure the continued integrity of the building's structure, thereby inhibiting the on-going deterioration.

The energy and financial appraisal also suggested a priority listing of overall improvements to the building in order to achieve a significant, economically justifiable reduction in energy demand; the recommended options are estimated to cost in total £39819. However, the capital cost of such an upgrading would only be recouped, and the theatre achieve a sustainable future, if the building were to be used more intensively and for a wider range of activities than at present in order to increase its revenue significantly.

All prices as stated are those at August 1991.     

Efficacy of an ivermectin controlled-release capsule against nematode and arthropod endoparasites in sheep

Five controlled trials were conducted in Germany or in the United Kingdom, using 74 female sheep of merino or Dorset horn breeds, to evaluate the efficacy of an ivermectin controlled-release capsule against naturally acquired or induced infections of gastrointestinal nematodes, lungworms and nasal bot larvae and against incoming infections with gastrointestinal and pulmonary nematodes. Half of the animals were treated with one ivermectin controlled-release capsule that delivered ivermectin at the rate of 1.6 mg per day for 100 days while the other half remained untreated. Parasites were counted 21, 28, 35 or 56 days after administration of the capsule. The treatment was highly effective (> or = 99 per cent) against established parasites of the following species: Haemonchus contortus (adults and fourth-stage larvae), Ostertagia circumcincta, O pinnata, O trifurcata, Ostertagia species fourth-stage larvae, Trichostrongylus axei, T colubriformis, T vitrinus, Cooperia curticei, Nematodirus battus, N filicollis, Strongyloides papillosus, Chabertia ovina, Oesophagostomum venulosum, Trichuris ovis, Tr skrjabini, Dictyocaulus filaria, Protostrongylus rufescens and Oestrus ovis (larvae). The treatment prevented the establishment of the gastrointestinal nematodes H contortus, O circumcincta, T axei, T colubriformis, C curticei, N battus, N filicollis, Ch ovina, Oe vennulosum and the establishment of the lungworm D filaria by > 99 per cent compared with untreated controls (P < or = 0.01).     

Dietary deficiency of docosahexaenoic acid impairs vision at low light intensities in juvenile herring (Clupea harengus L.)

In the retina of herring (Clupea harengus L.), rods are recruited from about 8 wk after hatching, and from this time there is a linear relationship between the number of rods in the photoreceptor cell population and the content of di22∶6n−3 molecular species of phospholipids. Juvenile herring were reared from four weeks' post-hatching for 15 wk on eitherArtemia nauplii deficient in 22∶6n−3 or on enrichedArtemia nauplii containing 4.3% 22∶6n−3. The visual performance of the fish was then determined at three light intensities (0.01, 0.1, and 1.0 lux) by observing their frequency of striking at liveArtemia nauplii using infrared video recording. Herring reared on the diet containing no 22∶6n−3 were less active predators, especially at the lowest light intensity where very few strikes were observed. The eyes of these fish contained greatly reduced levels of di22∶6n−3 molecular species of total phospholipid, 2.1% vs. 12.0% in fish supplemented with 22∶6n−3. The contribution of saturated and monounsaturated fatty acids in the molecular species of phosphatidylethanolamine (PE), phosphatidylserine (PS), and phosphatidylcholine (PC) was virtually unchanged, while 20∶5n−3 and 22∶5n−3 largely replaced 22∶6n−3. There was an almost complete disappearance of di22∶6n−3 PC, while the amounts of di22∶6n−3 PE and PS fell by 18.1 and 20.6% to 2.7 and 7.6%, respectively. The dipolyunsaturated molecular species di20∶5n−3, 20∶5n−3/22∶5n−3, and di22∶5n−3 made up a substantial part of the deficit. We conclude that a dietary deficiency of 22∶6n−3 during the period early in rod development impairs visual performance such that the fish can no longer feed at low light intensities. Deceased.