bluuebunny/crossref_metadata_2025 huggingface dataset:
Photosensitization of Escherichia coli and Saccharomyces cerevisiae by phenylheptatriyne from Bidens pilosa
Authors: Arnason Thor , Wat Chi-Kit , Downum Kelsey , Yamamoto Etsuo , Graham Elizabeth , Towers G. H. Neil
Published: May 2010

The photosensitizing action of 7-phenylhepta-2,4,6-triyne (PHT), a polyacetylenic compound isolated from Bidens pilosa L. (Asteraceae), has been studied using Escherichia coli and Saccharomyces cerevisiae as the test organisms. The survival curves for E. coli treated with PHT and ultraviolet (UV) radiation were obtained and have been interpreted quantitatively on the basis of a target theory model. The number of "targets" in the cell that must be destroyed before cell death occurs was estimated at six, whereas the dose, D0, that reduced the surviving fraction of the population to 1/e of its value was estimated to be 280 J/m2.Survival was enhanced in aerobic conditions as compared with anaerobic conditions, which is strong evidence that PHT does not behave as a photodynamic sensitizer in vivo. This view was confirmed by work with azide (a quencher of singlet oxygen), D2O (which increases the lifetime of singlet oxygen), and superoxide dismutase (which scavenges superoxide radicals). None of these treatments modified the survival curves significantly, indicating that activated species of O2 are probably not involved in photosensitizations with PHT in vivo.Cell respiration was found to be rapidly inhibited by mild treatments of PHT and UV radiation, suggesting that nuclear metabolism is not the primary target of photosensitization as is the case with another group of photosensitizers, the furanocoumarins. The available evidence indicates that PHT is a representative of a new class of phototoxic compounds. A mechanism of action involving production of free radicals is proposed.
Aspects of parasexual analysis in Aspergillus parasiticus
Authors: Bennett J. W. , Vinnett C. H. , Goynes Jr. W. R.
Published: May 2010

A scanning electron microscopic examination of the surface ornamentation of haploid, heterokaryotic, and diploid conidiospores of Aspergillus parasiticus is presented. Previous studies on the parasexual cycle in this aflatoxin-producing species have shown that heterozygous diploids may be isolated with ease. However, rational genetic analysis of diploids has been hampered by the nonrandom recovery of auxotrophic markers from heterozygous diploids. In this study, a double transfer method involving only brief exposure to p-fluorophenylalanine (FPA) allowed increased recovery of auxotrophic markers from heterozygous diploids. Extensive sampling of green-spored types from FPA-treated diploids provided an estimate of auxotrophic segregants not visually identifiable. We examined seven heterozygous diploids involving three spore color markers and eight auxotrophic markers. In addition, two mutants blocked in aflatoxin production which accumulated visually detectable aflatoxin precursors were analyzed. One linkage between an auxotrophic marker and a spore color marker was detected; however, no evidence for linkage was found between the blocked aflatoxin mutants and the other markers studied.
The methylating system for 3-sn-phosphatidylcholine biosynthesis in Fusarium oxysporum
Authors: Wilson Alan C. , Barran Leslie R.
Published: May 2010

Cell extracts of hyphae of Fusarium oxysporum f. sp. lycopersici rapidly transferred the methyl group of S-[methyl-3 H]adenosyl-L-methionine (Ado-Met) to endogenous phosphatidylethanolamine (PE). About 80% of the radioactivity incorporated into the phospholipid fraction was found in phosphatidylcholine (PC) while the rest of the radioactivity was present in the intermediates monomethylphosphatidylethanolamine (MePE) and dimethylphosphatidylethanolamine (DiMePE). The phospholipid methylating system had a pH optimum of 8.5, a Km of 30 μm for Ado-Met, and a Vmax of 10 nmol/h per milligram protein. The specific activity of the methylating system was highest in early log phase and lowest in the late log phase of growth.The activity of the cell-free methylating system was reduced by incubation at temperatures above 25 °C, and at 37 °C about 50% of the initial methylating activity remained after incubation for 15 min. In contrast, the activity of the in vivo methylation system almost doubled when the incubation temperature was raised from 25 to 37 °C.
Nutrition carbonée et étude taxonomique de Bacillus megaterium et B. cereus
Authors: Pichinoty F. , Durand M. , Mandel M.
Published: May 2010

Ten of the 14 strains of Bacillus cereus studied were isolated from pasteurized soil samples by a new selective technique which consists of the use of anaerobic enrichment cultures in peptone medium containing 0.5% KNO3. The 19 strains of B. megaterium use the following 21 sources of carbon and energy: D-glucose, D-galactose, D-fructose, D-mannose, D-glucosamine, D-gluconate, D-ribose, sucrose, cellobiose, maltose, raffinose, D-mannitol, glycerol, glycerate, pyruvate, fumarate, trans-aconitate, DL-aspartate, asparagine, L-glutamate, and L-glutamine. The 14 strains of B. cereus use the following 11 compounds: D-glucose, D-fructose, D-mannose, D-glucosamine, D-ribose, maltose, trehalose, glycerol, acetate, pyruvate, and L-glutamine. The eight strains of B. cereus var. mycoides use the following nine compounds: D-glucose, salicin, D-ribose, cellobiose, maltose, trehalose, glycerol, acetate, and pyruvate. Numerical taxonomy based on 151 characters shows that the 41 strains form two distinct groups. Group A includes the 19 strains of B. magateriurn; group B includes the 14 strains of B. cereus and the 8 strains of B. cereus var. mycoides. The guanine + cytosine content of the DNA of each strain was determined. The following mean values were obtained: B. megaterium, 40.6% ± 0.8; B. cereus, 38% ± 0.9; B. cereus var. mycoides, 38.4% ± 1.1.
Growth responses of oligotrophic and heterotrophic marine bacteria in various substrate concentrations, and taxonomic studies on them
Authors: Akagi Y. , Simidu U. , Taga N.
Published: May 2010

Growth responses of oligotrophic bacteria to substrate concentrations have been investigated in comparison with those of heterotrophic bacteria. The results suggested that oligotrophs were the group which could grow and produce a perceptible turbidity in the media containing less than 10 mg peptone C/L of medium.Taxonomic studies indicated that the most abundant group in the oligotrophic bacterial flora was consistent with that in the heterotrophic bacterial flora at each sampling station. However, the relative proportion of pseudomonads in the oligotrophs was higher than that in the heterotrophs (at stations H-24, H-28, H-29, Ab-1, Ab-2, and O-4), while the relative proportion of Vibrio in the former was lower than that in the latter (at stations H-24, H-28, H-29, O-4, and O-9).
An improved microslide immunodiffusion technique
Authors: Niilo L.
Published: May 2010

The microslide immunodiffusion technique of Wadsworth was modified to make it compatible with currently available laboratory equipment and to increase its efficiency, reliability, and precision. The wells in the acrylic template were enlarged to 2.0 mm to allow use of the Micro/Pettor C pipetting system for rapid, precise, uniform, and bubble-free filling of the wells. This technique has been used successfully for several immunological tests, particularly for the detection and assay of Clostridium perfringens enterotoxin and antienterotoxin.
Isolation of a nitrogen-fixing Campylobacter species from the roots of Spartina alterniflora Loisel
Authors: McClung C. R. , Patriquin D. G.
Published: May 2010

A microaerophilic nitrogen-fixing bacterium was isolated from surface-sterilized roots of Spartina alterniflora Loisel growing in a Nova Scotian salt marsh. It is a small curved rod and is motile with a single polar flagellum. Metabolism is respiratory. Organic and amino acids, but not carbohydrates, serve as carbon and energy sources. The guanine + cytosine content of its deoxyribonucleic acid is 32.1 ± 1.0 mol%. Based upon morphological and biochemical characteristics this organism is assigned to the genus Campylobacter Sebald and Veron 1963. It is distinguishable from other campylobacters by the presence of nitrogenase and urease, by the production of pigment from tryptophan, and by a combination of other biochemical traits. The association of this organism with plant roots further distinguishes it from other campylobacters which commonly inhabit animal, including human, tissues.
The effect of inorganic and organic mercury on growth kinetics of Nitzschia acicularis W. Sm. and Tetraselmis suecica Butch.
Authors: Mora B. , Fábregas J.
Published: May 2010

Studies have been made on the toxicities of three inorganic (HgCl2, HgSO4, and NH2HgCl) and two organic (CH3HgCl and phenyl mercuric acetate (PMA)) mercury derivatives on planktonic algae (Nitzschia acicularis W. Sm. and Tetraselmis suecica Butch.). Growth kinetics and fluorescence changes were used as criteria for assessing algal–metal responses.Methylmercury chloride was found to be the more toxic form, inhibiting growth of both species at levels of 0.025 ppm Hg. PMA inhibited Nitzschia at the same concentration. Inorganic forms prevent growth of the diatom at 0.15–0.20 ppm Hg. Addition of inorganic mercury at concentrations of 0.05 ppm Hg resulted in reduction of the lag phase, increase in exponential growth rate, or both. Increasing mercury concentrations caused a gradual increase in the lag phase in T. suecica and in N. acicularis only with mercuric sulphate. Populations recovered from this initial effect and started to grow. The effect of inoculum size on mercurial toxicity was tested. The higher concentrations of mercury that still permit growth restricted the chlorophyll fluorescence to the central cellular area and the cells appear slimmed. This effect is highest in concentrations that inhibit growth.
N2 fixation in the rhizosphere of Thalassia testudinum
Authors: Capone Douglas G. , Taylor Barrie F.
Published: May 2010

N2 fixation (C2H2 reduction) associated with the roots, rhizomes, and sediments (rhizosphere cores) of the seagrass Thalassia testudinum was measured at sites in South Florida (Soldier Key, Biscayne Bay) and the Bahamas (Bimini Harbor). Rates of C2H2 reduction were higher in anaerobic than in aerobic assays and were linear for several hours after an initial lag period of 1–2 h. Nitrogenase activity was proportional to the weight of rhizomes plus roots but showed no correlation with the total weight of the rhizosphere cores. C2H2 reduction occurred to depths of at least 30 cm but the majority (>85%) of the activity was in the 0- to 20-cm fraction; also the ratio of activities for the 0- to 10- and 10- to 20-cm depths was about 2:1. Most investigations were carried out using anaerobic assays of the 0- to 10-cm fractions and rates calculated for the period of 3–6 h after adding C2H2. These rates were not stimulated by organic compounds (glucose, lactate, succinate) but were approximately halved by a decrease in temperature of 10 °C. In a seasonal study at Soldier Key the rates of N2 fixation varied about 20-fold with maximal rates in late summer and minimal rates in winter (January). On a diurnal basis, C2H2 reduction increased in the morning but was depressed in midafternoon, probably due to O2 buildup in the rhizosphere. Daily rates of N2 fixation, during the summer months of 1975–1978, varied between 5 and 24 mg N m−2 and the estimated annual rates of N2 fixation were 10–50 kg N ha−1, taking into account seasonal variations and activities to a depth of 20 cm.
Sensitivity of some Erwinia carotovora serogroups to macromolecular bacteriocins
Authors: Crowley C. F. , Boer S. H. de
Published: May 2010

Representative strains from each of 18 Erwinia carotovora serogroups were tested for bacteriocin activity. Eight bacteriocin producing strains were found and the bacteriocins partially purified by ammonium sulfate fractionation and high-speed centrifugation. Bacteriocins from all eight strains were morphologically similar to bacteriophage tails. Specific absorption of bacteriocins from one of the antagonistic strains to sensitive bacterial cells was demonstrated with electron microscopy. In four of the serogroups tested each strain was sensitive to only one or two of the bacteriocins while in other serogroups sensitivity varied. Strains of both E. carotovora var. atroseptica and E. carotovora var. carotovora were sensitive to the same bacteriocins, but the two serogroups of var. atroseptica could be differentiated from each other on the basis of sensitivity to one bacteriocin.
Characterization of an effective actinorhizal microsymbiont, Frankia sp. AvcI1 (Actinomycetales)
Authors: Baker Dwight , Torrey John G.
Published: May 2010

The actinomycete, Frankia sp. AvcI1, isolated from root nodules of Alnus viridis ssp. crispa was grown in axenic culture and used to inoculate host seedlings. This bacterium has been shown to be an infective and effective nitrogen-fixing microsymbiont which can be distinguished from other frankiae, in vitro, on the basis of size, distinctive morphology, and growth characteristics. Cross-inoculation studies indicated that the host range of this symbiont encompasses all of the members of the genera Alnus, Myrica, and Comptonia tested. In all cases, the symbioses developed were effective in fixing atmospheric dinitrogen.
Characterization of an ineffective actinorhizal microsymbiont, Frankia sp. EuI1 (Actinomycetales)
Authors: Baker Dwight , Newcomb William , Torrey John G.
Published: May 2010

The actinomycete, Frankia sp. EuI1, isolated from root nodules of Elaeagnus umbellata is an infective endophyte but which lacks the ability to form an effective nitrogen-fixing symbiosis with its host. This ineffective organism can be distinguished easily from other frankiae, in vitro, on the basis of size, morphology, and the elaboration of a diffusible pigment. Cross-inoculation studies indicated that the host range of this symbiont is narrow and probably restricted to the Elaeagnaceae. In all cases of nodulation the symbiosis never developed nitrogenase activity and the microsymbiont never produced endophytic vesicles within the infected host cells. Sporangia were produced in vivo and in vitro so the morphogenetic block is apparently restricted to vesicle formation.
Hydrogen metabolism of Azospirillum brasilense in nitrogen-free medium
Authors: Chan Y. K. , Nelson L. M. , Knowles R.
Published: May 2010

Production of H2 by Azospirillum brasilense under N2-fixing conditions was studied in continuous and batch cultures. Net H2 production was consistently observed only when the gas phase contained CO. Nitrogenase activity (C2H2 reduction) and H2 evolution (in the presence of 5% CO) showed a similar response to O2 and were highest at 0.75% dissolved O2. Uptake hydrogenase activity, ranging from 0.3 to 2.5 μmol H2/mg protein per hour was observed in batch cultures under N2. Such rates were more than sufficient to recycle nitrogenase-produced H2. Tritium-exchange assay showed that H2 uptake was higher under Ar than under N2. Uptake hydrogenase was strongly inhibited by CO and C2H2. Cyclic GMP inhibited both nitrogenase and uptake hydrogenase activities.
Hyphal tip growth in Achlya. II. Subcellular localization of cellulase and associated enzymes
Authors: Hill T. W. , Mullins J. T.
Published: May 2010

The isolation and characterization of cellulase-containing membranes of Achlya ainbisexnalis Raper was attempted by differential and density gradient centrifugations. Maximum cellulase activity was found at an isopycnic density of 1.19 g/cm3, although some activity was found at other densities. A similar distribution of activity was shown by IDPase, ATPase, UDPG transferase, and by sedimentable carbohydrate. The coequilibration and steady enrichment of these activities during purification suggests their presence in a single type of subcellular particle. It was not possible to identify clearly the particle(s) in question from isolated fractions by electron microscopy, but when compared with the cytochemical localization of carbohydrate and IDPase in intact hypha, cytoplasmic vesicles with 150-mm diameters seem to be likely candidates.
Lignin degradation by Phanerochaete chrysosporium in hyperbaric oxygen
Authors: Reid Ian D. , Seifert Keith A.
Published: May 2010

Phanerochaete chrysosporium degraded aspen wood lignin as well in 2 atm O2 (1 atm = 101.325 kPa) as in 1 atm O2, but 3 atm O2 inhibited the fungus, and O2 pressures above 4 atm killed it. Lignin degradation in 5 atm of air was similar to that in 1 atm of O2, indicating that O2 concentration, not pressure, was the inhibitory factor. The selectivity with which P. chrysosporium metabolised lignin in preference to other wood components did not increase at O2 pressures above 1 atm.
Characterization of Bacteroides asaccharolyticus and B. melaninogenicus oral isolates
Authors: Mayrand Denis , McBride Barry C. , Edwards Thomas , Jensen S.
Published: May 2010

Experiments were designed to characterize a number of oral "pigmented" Bacteroides isolates with regard to their pathogenicity in an experimental model system and a number of other properties. These include fatty acid determination, hemagglutination studies, collagenase and protease activities, and vitamin K. dependency. Oral B. asaccharolyticus and B. melaninogenicus isolates differed from one another in phenylacetic acid production, hemagglutination, collagenase activity, and pathogenicity. All B. asaccharolyticus were found to be pathogenic in the in vivo mixed infection model and this property could be correlated with biochemical and enzymatic activities.
Psychrophiles, psychrotrophs, and mesophiles in an environment which experiences seasonal temperature fluctuations
Authors: Ferroni G. D. , Kaminski J. S.
Published: May 2010

The quantification of psychrophilic/psychrotrophic and mesophilic, heterotrophic bacteria from a lake which experiences seasonal temperature fluctuations showed that the psychrophilic/psychrotrophic population ranged in number from 1212 to 87 000/mL, whereas the mesophilic population ranged from 67to3783/mL, for sediment–water interface samples over the yearly cycle. The relative abundance of psychrophiles/psychrotrophs and mesophiles varied with season, but psychrophilic/psychrotrophic bacteria were found to predominate on every sampling occasion. A considerable number of the 37 °C isolates were found to be psychrotrophs having broad temperature ranges for growth. An especially notable result was the isolation of psychrophiles on every sampling occasion, and in such high numbers, from this "nonpermanently cold" environment.A total of 388 isolates were described according to Gram reaction, colony and cell morphology, biochemical activities, and thermal type, and on the basis of similarities they were grouped into 158 "working types." Many of the "working types" were capable of gelatinase, amylase, chitinase, and lipase production.A comparison of the generation times of the psychrophilic/psychrotrophic and mesophilic "working types" with their frequencies of occurrence, for all four samplings, did not reveal a direct relationship between numerical predominance and growth rate as determined by temperature.
Modulation of the rats' immune status by monoassociation with anaerobic bacteria
Authors: Wells Carol L. , Balish Edward
Published: May 2010

The capacity of a pure culture of anaerobic intestinal bacteria to influence the host's cellular and humoral immune systems was investigated with germfree, monoassociated, and conventionally reared rats. Monoassociation of germfree rats with Bacteroides fragilis stimulated the production of serum gamma globulin, agglutinating antibodies, and an apparent IgG (Immunoelectrophoresis) band. A comparison of the in vitro blastogenic potential of lymphocytes (spleen cells and mesenteric lymph node cells) from germfree, monoassociated, and conventionally reared rats indicated the following: (1) the microbial flora had no obvious effect on the capacity of nonstimulated lymphocytes to incorporate [3H]thymidine; (2) spleen cells from conventionally reared rats responded to phytohemagglutinin, concanavilin A, or pokeweed mitogen better than splenocytes from germfree rats; (3) colonization of germfree rats with Fusobacterium necrophorum increased the responsiveness of splenocytes to photohemagglutinin and concanavilin A; and (4) monoassociation of germfree rats with B. fragilis. but not with F. necrophorum or Propionibacterium acnes, increased splenocyte blastogenesis to homologous (i.e., colonizing) bacterial antigens. This study indicated that some intestinal bacteria can modulate the immune status of the host; the extent and nature of this modulation depended on the particular species of colonizing bacteria.
Preliminary report on the observation of a coronavirus in the intestine of the laboratory rabbit
Authors: Lapierre J. , Marsolais G. , Pilon P. , Descôteaux J.-P.
Published: May 2010

Intestinal infections are a major cause of mortality in domestic rabbits. Although a few pathogenic organisms have been associated with this type of infection, it is often impossible to demonstrate the presence of any etiologic agents.Recently viral particles were observed in the intestine of diseased rabbits submitted to our laboratory for diagnosis. A study was then initiated to evaluate the presence of viral agents in the intestine of rabbits showing clinical signs of enteritis. Viral particles with morphological characteristics of the Coronaviridae family were observed by electron microscopy in most specimens of fecal material obtained from sick rabbits. Such particles were not seen in the feces of healthy animals.These particles, which have a density of 1.07–1.18 g/cm3 on sucrose gradient, hemagglutinate rabbit red blood cells. Furthermore this virus has some antigenic relationship with the human coronavirus 229-E since immune serum to this virus blocks the hemagglutination of the rabbit erythrocytes.Antibody titers to this virus were detected in rabbit sera obtained from colonies with a high incidence of intestinal infections.When fecal material containing coronavirus particles were inoculated on various tissue culture systems, no cytopathic effects were observed.
Factors affecting the production of hydrogenase by Desulfovibrio desulfuricans
Authors: Martin S. M. , Glick B. R. , Martin W. G.
Published: May 2010

An examination of conditions for the growth of Desulfovibrio desulfuricans, with the aim of optimizing hydrogenase production, is reported. An ammonium sulfate – lactate – yeast extract medium gave 5 to 10 times as much hydrogenase activity as a peptone – yeast extract medium. It made little if any difference whether the gas used for sparging was nitrogen, hydrogen, or a mixture thereof but increasing the rate of sparging and agitation did result in a slight decrease in activity. Control of pH during culture development was of little benefit to hydrogenase production. At least two hydrogenases were present in D. desulfuricans: one periplasmic, the other membrane bound.Desulfovibrio desulfuricans produced more hydrogenase than did either D. gigas and D. vulgaris.
Purification and partial characterization of a 33 000 molecular weight endonuclease associated with human adenovirus type 5
Authors: Tsang Linda W.-L. , Marusyk R. G.
Published: May 2010

An endonuclease activity has been purified from human adenovirus type 5 (HAd5) virions and HAd5-infected cell extracts. The endonuclease activity is associated with a monomeric protein of molecular weight approximately 33 000. The endonuclease activity is more active at pH 4.5 than pH 7.2. Incubation of the enzyme at room temperature for periods of longer than 96 h results in a substantial increase in activity. The endonuclease activity is sensitive to EDTA at concentrations 10 mM or greater but is insensitive to 500 mM NaCl. Immunological analysis with endonuclease specific antiserum indicates that the endonuclease may be a host cell derived, viral modified, and incorporated protein.
Distribution of Vibrio parahaemolyticus in finfish harvested from Porto Novo (S. India) environs: a seasonal study
Authors: Nair G. Balakrish , Abraham Martin , Natarajan R.
Published: May 2010

A seasonal survey was undertaken to elucidate the incidence of Vibrio parahaemolyticus in freshly caught and market samples of fish collected from five distinct locales near Porto Novo. Vibrio parahaemolyticus was isolated from 35.6 and 40.6% of freshly harvested fishes from the estuary and mangroves, respectively, while only 3.9% of freshly caught specimens originating from the Bay of Bengal were positive for the pathogen. Isolation rates of 46.8% for fishes from the landing site and 40.6% for fishes from the fish market were recorded. Vibrio parahaemolyticus was more readily recovered from market samples of fish (44%) compared with freshly caught brackish water fishes (37.5%). Incidence of V. parahaemolyticus was higher during summer (March–July) than in other seasons.
The effects of organophosphorus pesticides on estuarine ammonium oxidizers
Authors: Jones R. D. , Hood Mary A.
Published: May 2010

The effects of seven thiophosphorus pesticides and their degradation products on estuarine ammonium oxidizers were examined. Using an axenic, closed-culture, high cell density assay, the pesticides caused little inhibition of ammonium oxidation. However, the degradation product of methyl parathion, p-aminophenol, significantly inhibited ammonium oxidation in levels as low as 0.01 mg/L. Estuarine sediments containing indigenous ammonium oxidizers were exposed to the pesticides over a 14-day period and activity of the ammonium oxidizers were inhibited after 14 days. Three pesticides were aged in estuarine sediments under aerobic, anaerobic, and microaerophilic conditions, and axenic cultures of ammonium oxidizers were exposed to the resulting metabolites. Ammonium oxidation was inhibited by 10% in the systems containing pesticides aged under aerobic and anaerobic conditions, whereas under microaerophilic conditions, 20% reduction in activity was observed. The data suggest that the parent compounds of the thiophosphorus pesticides have little effect on ammonium oxidation in estuarine sediments, but that certain metabolites which accumulate from the decomposition of these pesticides, especially in sediments under low O2 levels, may significantly reduce ammonium oxidation.
The comparison of rhapidosomes and defective bacteriophage particles from Aquaspirillum itersonii
Authors: Evers Martin C. J. M. , Murray R. G. E.
Published: May 2010

Aquaspirillum itersonii spontaneously produces rhapidosomes. These structures, which are found throughout the cell cycle, are compared with the defective bacteriophage particles that can be induced by mitomycin C treatment (0.5 μg/mL). The rhapidosomes are composed of three proteins (MW 63 000, 23 500, and 15 000). The defective bacteriophage particles are composed of two proteins (MW 50 000 and 17 500). The defective bacteriophage particles do not react with anti-rhapidosomal protein antiserum. These results indicate that the rhapidosomes are not polysheaths of the defective bacteriophage particles inducible in this organism as earlier proposed in the literature. It is concluded that the rhapidosomes of A. itersonii are an assembly of three proteins that are distributed in the cytosol after synthesis and are present at all times in the growth cycle.
Prophage-mediated production of a bacteriocinlike substance by SPβ lysogens of Bacillus subtilis
Authors: Hemphill H. Ernest , Gage Irene , Zahler Stanley A. , Korman Ruth Z.
Published: May 2010

Cultures of Bacillus subtilis lysogenic for the temperate bacteriophage SPβ release "betacin," a bacteriocinlike substance that inhibits B. subtilis strains which do not carry this phage. Production of betacin is blocked by mutations in the bet gene on the prophage and a second phage gene, tol, is apparently involved in making the lysogen itself tolerant to betacin. Mutations in a bacterial gene betR, located on the B. subtilis chromosome between metC and pyrD, render nonlysogens tolerant to betacin.
Deposit assessment of Bacillus thuringiensis formulations applied from an aircraft
Authors: Smirnoff W. A.
Published: May 2010

Deposit assessment after aerial spraying with Bacillus thuringiensis (B.t.) formulations consists of the analysis of the splash of droplets on Kromekote papers and determining the number of bacterial colonies growing on nutrient agar medium in Petri dishes. However, neither of these two methods provides a number of spores deposited although this figure is essential to determine treatment efficiency. Both methods are evaluated with regard to this need and a new approach is suggested.
COMPARISON OF PRISM-BASED OPTICAL PROBES FOR LIQUID MONITORING
Authors: GOLNABI H. , RAZANI M.
Published: May 2010

In this article, two possible applications of prism-based probes for liquid-switching, level-sensing, and as a refractometer are described. Theoretical formulation is developed for the emergent intensity for each system and possible range of operation for each system is reported. By comparing the theoretical investigations, some hints are given in optimum usage of prism in each case. Variation of the beam divergence, incident angle, and prism glass index are major parameters that are considered in this investigation. The obtained results are compared with some available experimental results and practical points concerning the effective application of each geometry is reported. Theoretical expressions developed here are in good agreement with the experimental measurements.
ALGEBRAIC CHARACTERIZATION OF LOGICALLY DEFINED TREE LANGUAGES
Authors: ÉSIK ZOLTÁN , WEIL PASCAL
Published: May 2010

We give an algebraic characterization of the tree languages that are defined by logical formulas using certain Lindström quantifiers. An important instance of our result concerns first-order definable tree languages. Our characterization relies on the usage of preclones, an algebraic structure introduced by the authors in a previous paper, and of the block product operation on preclones. Our results generalize analogous results on finite word languages, but it must be noted that, as they stand, they do not yield an algorithm to decide whether a given regular tree language is first-order definable.
RELIABILITY PROPERTIES OF MEAN TIME TO FAILURE IN AGE REPLACEMENT MODELS
Authors: ASHA G. , UNNIKRISHNAN NAIR N.
Published: May 2010

In this article some properties of the mean time to failure in an age replacement model is presented by examining the relationship it has with hazard (reversed hazard) rate and mean (reversed mean) residual life functions. An ordering based on mean time to failure is used to examine its implications with other stochastic orders.
RANDOM AND AGE REPLACEMENT POLICIES
Authors: CHEN MINGCHIH , MIZUTANI SATOSHI , NAKAGAWA TOSHIO
Published: May 2010

This paper proposes a random and age replacement policy for an operating unit which works at random times. First, the unit is replaced before failure at a planned time T or at the completion of a working time, whichever occurs first. The expected cost rate is obtained. Next, as one extended model, the unit is replaced before failure at a number N of working times or at a planned time T. An optimal policy which minimizes the expected cost rate is discussed analytically, and its numerical example is given. Two modified models, where the unit is replaced at the first completion of the working time over time T or at number N, and it is replaced at time T or number N, whichever occurs last, are considered. Furthermore, we show that this corresponds to a cumulative damage model by replacing shock with work. Finally, one optimization problem of how much time to preset for scheduling the completion of N works is proposed.
Photophysical properties of microencapsulated phthalocyanines
Authors: Diz Virginia E. , Gauna Gabriela A. , Strassert Cristian A. , Awruch Josefina , Dicelio Lelia E.
Published: May 2010

Lipophilic substituted zinc(II) phthalocyanines: 2,3,9,10,16,17,23,24-octakis[(N,N-dimethylaminoethylsulfanyl)]phthalocyaninatozinc(II) (S1) and tetrakis(N,N-dibutylaminoethoxy)phthalocyaninatozinc(II) (3) were incorporated into soybean L-α-phosphatidylcholine (SPC) liposomes of 100 nm diameter. Liposomes were characterized by static light scattering (SLS), transmission electronic microscopy (TEM), and differential scanning calorimetry. The fluorescence quantum yield and singlet molecular oxygen production of 3 are Φ F = 0.15 and ΦΔ = 0.24, respectively, whereas the same photophysical parameters for S1 are Φ F = 0.13 and ΦΔ = 0.51. Higher values of Φ F and ΦΔ are obtained in organic solvent for both dyes. Synthesis of compound 3 has also been reported.
Temperature Dependence of Photoluminescence in Layered Semiconductor n-GaS Doped with Sn
Authors: Shigetomi Shigeru , Ikari Tetsuo
Published: May 2010

The radiative recombination mechanisms of Sn-doped GaS have been investigated by photoluminescence (PL) measurements. The PL spectrum at 77 K appears in the energy region between 1.25 and 2.3 eV and is dominated by two emission bands. The temperature dependence of the full-width at half-maximum and the shapes of the PL spectra of the two emission bands are characterized by the recombination mechanism of the configurational coordinate model. The origins of the two emission bands are related to the complex centers of vacancies and impurity atoms.
Structural Elements of Ultrashallow Thermal Donors Formed in Silicon Crystals
Authors: Hara Akito , Awano Teruyoshi , Ohno Yutaka , Yonenaga Ichiro
Published: May 2010

It has been reported by one of the authors (A.H.) of the present study that ultrashallow thermal donors (USTDs) with a hydrogen-like electronic structure are formed in C- and N-doped O-rich Si crystals at approximately 450–600 °C. In this paper, it is reported that there are two types of USTDs: USTDs comprising C, H, and O [D(C,H,O)s] and USTDs comprising C, N, and O [D(C,N,O)s]. The thermal stability of these two types of donors was different; D(C,N,O)s were stable at 600 °C, while D(C,H,O)s were not stable at approximately 600 °C.
Photoluminescence Characteristics of Organic Host Materials with Wide Energy Gaps for Organic Electrophosphorescent Devices
Authors: Endo Ayataka , Adachi Chihaya
Published: May 2010

The photoluminescence, i.e., fluorescence and phosphorescence, characteristics of host materials with wide energy gaps suitable for phosphorescence-based organic light-emitting diodes (OLEDs) are summarized. In the vacuum deposited films, the host materials show phosphorescent emission in the blue to green region and triplet energy levels of E
T = 2.6–3.1 eV because of the presence of steric hindrance. An OLED containing 1,2,3,4-tetraphenyl-5-(3-pyridyl)benzene as a host and iridium(III) bis[(4,6-difluorophenyl)-pyridinato-N,C
2]picolinate as a blue emissive phosphorescent dopant exhibits an external electroluminescence efficiency of ∼12%.
Stepsize selection for ordinary differential equations
Authors: Krogh Fred T.
Published: May 2010

This note offers a new approach based on a least squares fit to past data in order to select the stepsize when solving an ordinary differential equation. The approach used may have applicability to other situations where one wants to repeatedly make short term predictions given somewhat noisy data. Additional ad hoc rules help significantly for reliability and efficiency. Comparisons with some Runge-Kutta codes, an Adams code, and an extrapolation code are also included.
A fast and robust mixed-precision solver for the solution of sparse symmetric linear systems
Authors: Hogg J. D. , Scott J. A.
Published: May 2010

On many current and emerging computing architectures, single-precision calculations are at least twice as fast as double-precision calculations. In addition, the use of single precision may reduce pressure on memory bandwidth. The penalty for using single precision for the solution of linear systems is a potential loss of accuracy in the computed solutions. For sparse linear systems, the use of mixed precision in which double-precision iterative methods are preconditioned by a single-precision factorization can enable the recovery of high-precision solutions more quickly and use less memory than a sparse direct solver run using double-precision arithmetic.

In this article, we consider the use of single precision within direct solvers for sparse symmetric linear systems, exploiting both the reduction in memory requirements and the performance gains. We develop a practical algorithm to apply a mixed-precision approach and suggest parameters and techniques to minimize the number of solves required by the iterative recovery process. These experiments provide the basis for our new code HSL_MA79—a fast, robust, mixed-precision sparse symmetric solver that is included in the mathematical software library HSL.

Numerical results for a wide range of problems from practical applications are presented.
Scaling and pivoting in an out-of-core sparse direct solver
Authors: Scott Jennifer A.
Published: May 2010

Out-of-core sparse direct solvers reduce the amount of main memory needed to factorize and solve large sparse linear systems of equations by holding the matrix data, the computed factors, and some of the work arrays in files on disk. The efficiency of the factorization and solution phases is dependent upon the number of entries in the factors. For a given pivot sequence, the level of fill in the factors beyond that predicted on the basis of the sparsity pattern alone depends on the number of pivots that are delayed (i.e., the number of pivots that are used later than expected because of numerical stability considerations). Our aim is to limit the number of delayed pivots, while maintaining robustness and accuracy. In this article, we consider a new out-of-core multifrontal solver HSL_MA78 from the HSL mathematical software library that is designed to solve the unsymmetric sparse linear systems that arise from finite element applications. We consider how equilibration can be built into the solver without requiring the system matrix to be held in main memory. We also examine the effects of different pivoting strategies, including threshold partial pivoting, threshold rook pivoting, and static pivoting. Numerical experiments on problems arising from a range of practical applications illustrate the importance of scaling and show that, in some cases, rook pivoting can be more efficient than partial pivoting in terms of both the factorization time and the sparsity of the computed factors.
Algorithm 902
Authors: Rao Anil V. , Benson David A. , Darby Christopher , Patterson Michael A. , Francolin Camila , Sanders Ilyssa , Huntington Geoffrey T.
Published: May 2010

An algorithm is described to solve multiple-phase optimal control problems using a recently developed numerical method called the
Gauss pseudospectral method
. The algorithm is well suited for use in modern vectorized programming languages such as FORTRAN 95 and MATLAB. The algorithm discretizes the cost functional and the differential-algebraic equations in each phase of the optimal control problem. The phases are then connected using linkage conditions on the state and time. A large-scale nonlinear programming problem (NLP) arises from the discretization and the significant features of the NLP are described in detail. A particular reusable MATLAB implementation of the algorithm, called
GPOPS
, is applied to three classical optimal control problems to demonstrate its utility. The algorithm described in this article will provide researchers and engineers a useful software tool and a reference when it is desired to implement the Gauss pseudospectral method in other programming languages.
Personal photo enhancement using example images
Authors: Joshi Neel , Matusik Wojciech , Adelson Edward H. , Kriegman David J.
Published: May 2010

We describe a framework for improving the quality of personal photos by using a person's favorite photographs as examples. We observe that the majority of a person's photographs include the faces of a photographer's family and friends and often the errors in these photographs are the most disconcerting. We focus on correcting these types of images and use common faces across images to automatically perform both global and face-specific corrections. Our system achieves this by using face detection to align faces between “good” and “bad” photos such that properties of the good examples can be used to correct a bad photo. These “personal” photos provide strong guidance for a number of operations and, as a result, enable a number of high-quality image processing operations. We illustrate the power and generality of our approach by presenting a novel deblurring algorithm, and we show corrections that perform sharpening, superresolution, in-painting of over- and underexposured regions, and white-balancing.
Distributed gradient-domain processing of planar and spherical images
Authors: Kazhdan Michael , Surendran Dinoj , Hoppe Hugues
Published: May 2010

Gradient-domain processing is widely used to edit and combine images. In this article we extend the framework in two directions. First, we adapt the gradient-domain approach to operate on a spherical domain, to enable operations such as seamless stitching, dynamic-range compression, and gradient-based sharpening over spherical imagery. An efficient streaming computation is obtained using a new spherical parameterization with bounded distortion and localized boundary constraints. Second, we design a distributed solver to efficiently process large planar or spherical images. The solver partitions images into bands, streams through these bands in parallel within a networked cluster, and schedules computation to hide the necessary synchronization latency. We demonstrate our contributions on several datasets including the Digitized Sky Survey, a terapixel spherical scan of the night sky.
Using blur to affect perceived distance and size
Authors: Held Robert T. , Cooper Emily A. , O'Brien James F. , Banks Martin S.
Published: May 2010

We present a probabilistic model of how viewers may use defocus blur in conjunction with other pictorial cues to estimate the absolute distances to objects in a scene. Our model explains how the pattern of blur in an image together with relative depth cues indicates the apparent scale of the image's contents. From the model, we develop a semiautomated algorithm that applies blur to a sharply rendered image and thereby changes the apparent distance and scale of the scene's contents. To examine the correspondence between the model/algorithm and actual viewer experience, we conducted an experiment with human viewers and compared their estimates of absolute distance to the model's predictions. We did this for images with geometrically correct blur due to defocus and for images with commonly used approximations to the correct blur. The agreement between the experimental data and model predictions was excellent. The model predicts that some approximations should work well and that others should not. Human viewers responded to the various types of blur in much the way the model predicts. The model and algorithm allow one to manipulate blur precisely and to achieve the desired perceived scale efficiently.
An optimization framework for embedded processors with auto-addressing mode
Authors: Zhuang Xiaotong , Pande Santosh
Published: May 2010

Modern embedded processors with dedicated address generation unit support memory accesses through auto-increment/decrement addressing mode. The auto-increment/decrement mode, if properly utilized, can save address arithmetic instructions, reduce static and dynamic memory footprint of the program, and speed up the execution as well.

Liao [1995, 1996] categorized this problem as Simple Offset Assignment (SOA) and General Offset Assignment (GOA), which involves storage layout of variables and assignment of address registers, respectively, proposing several heuristic solutions. This article proposes a new direction for investigating the solution space of the problem. The general idea [Zhuang 2003] is to perform simplification of the underlying access graph through coalescence of the memory locations of program variables. A comprehensive framework is proposed including coalescence-based offset assignment and post/pre-optimization. Variables not interfering with others (not simultaneously live at any program point) can be coalesced into the same memory location. Coalescing allows simplifications of the access graph yielding better SOA solutions; it also reduces the address register pressure to such low values that some GOA solutions become optimal. Moreover, it can reduce the memory footprint both statically and at runtime for stack variables. Our second optimization (post/pre-optimization) considers both post- and pre-modification mode for optimizing code across basic blocks, which makes it useful. Making use of both addressing modes further reduces SOA/GOA cost and our post/pre-optimization phase is optimal in selecting post or pre mode after variable offsets have been determined.

We have shown the advantages of our framework over previous approaches to capture more opportunities to reduce both stack size and SOA/GOA cost, leading to more speedup.
Nomadic pict
Authors: Sewell Peter , Wojciechowski Paweł T. , Unyapoth Asis
Published: May 2010

Mobile computation, in which executing computations can move from one physical computing device to another, is a recurring theme: from OS process migration, to language-level mobility, to virtual machine migration. This article reports on the design, implementation, and verification of overlay networks to support reliable communication between migrating computations, in the Nomadic Pict project. We define two levels of abstraction as calculi with precise semantics: a low-level Nomadic π calculus with migration and location-dependent communication, and a high-level calculus that adds location-independent communication. Implementations of location-independent communication, as overlay networks that track migrations and forward messages, can be expressed as translations of the high-level calculus into the low. We discuss the design space of such overlay network algorithms and define three precisely, as such translations. Based on the calculi, we design and implement the Nomadic Pict distributed programming language, to let such algorithms (and simple applications above them) to be quickly prototyped. We go on to develop the semantic theory of the Nomadic π calculi, proving correctness of one example overlay network. This requires novel equivalences and congruence results that take migration into account, and reasoning principles for agents that are temporarily immobile (e.g., waiting on a lock elsewhere in the system). The whole stands as a demonstration of the use of principled semantics to address challenging system design problems.