bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow cytometric analysis for ploidy level differentiation of 45 hairy vetch accessions
Authors: YEATER KATHLEEN M , BOLLERO GERMAN A , BULLOCK DONALD G , RAYBURN A LANE
Published: July 2006

Determining the ploidy of plant germplasm is a necessary step in breeding or genetic studies in species. The purpose of this research was to determine the presence of ploidy level differentiation of hairy vetch (Vicia villosd) germplasm. Flow cytometry and root tip chromosome squashing methods were employed to assess 45 accessions labeled V. villosa available through the USDA germplasm collection. Flow cytometry determined that 43 of the accessions were 2C, one accession was 4C, and one accession was 6C. Analysis of accessions by root tip chromosome counts indicated that all accessions were diploid. The 2C accession contains 14 chromosomes and their chromosomes were approximately one‐half and one‐third in size as compared to the chromosomes of the 4C and 6C accessions, respectively. The 4C accession was observed to have 16 chromosomes and the 6C accession was observed to have 14 chromosomes. The large‐scale differences in DNA amounts were due to chromosomal size variability as opposed to ploidy differences. This revealed the incidence of species misidentification of these two V. villosa accessions to be Vicia pannonica. All the V. villosa accessions were observed to be diploid and have similar DNA amounts. Flow cytometry proved to be useful in the efficient assessment of these accessions.
Control of potato cyst nematodes and economic benefits of application of 1,3‐dichloropropene and granular nematicides
Authors: MINNIS S T , HAYDOCK P P J , EVANS K
Published: July 2006

The two species of the potato cyst nematodes (PCN) Globodera pallida and G rostochiensis are the most problematic pests of the potato crop in the UK. There are no commercially available cultivars with full resistance to G. pallida and both crop rotation and granular nematicides are less effective at controlling this species than G. rostochiensis. In situations of very high PCN levels it may be possible to reduce populations and yield losses by using an autumn application of the soil fumigant 1,3‐dichloropropene (1,3‐D) followed by a spring application of a granular nematicide. Two field experiments were done to look at the integration of methods for the control of PCN. The Common Field experiment (G. rostochiensis infested) compared the use of 1,3‐D with the granular nematicides aldicarb, oxamyl and fosthiazate when growing the susceptible cv. Estima. The Four Gates experiment (infested with both PCN species but mainly G rostochiensis) compared the performance of cv. Santé (partially resistant to G. pallida, fully resistant to G. rostochiensis) with that of the susceptible cv. Estima when treated with 1,3‐D and oxamyl at full and half‐rates. The results of the experiments show that an integrated approach to nematode control on heavily infested sites, including granular and fumigant nematicides and cultivar resistance, can lead to significant decreases in nematode population densities and reduce yield losses. An economic evaluation of the experiments modelled the gross margins from the different nematicide treatments. In Common Field, the highest gross margins were achieved with the combined use of fumigant and granular nematicides. In Four Gates, there was a clear economic benefit for both cultivars from the use of 1,3‐D. In this experiment, oxamyl was of economic value to Estima but not to Sante and full‐rate oxamyl was of more benefit than half‐rate to Estima.
Spatial and temporal patterns of abundance of the potato leafhopper among red maples
Authors: BENTZ J , TOWNSEND A M
Published: July 2006

A study was conducted in the 2001 growing season to examine the relative abundance, dispersion and distribution of the potato leafhopper (Empoasca fabae) among trees of 24 red maple (Acer rubrum) clonal selections. Yellow sticky traps hung from the trees were used to estimate the relative number of aerial potato leafhoppers among trees, starting on 1 May 2001 and stopping on 4 September 2001. More insects were collected from the east side of the plot than from the other sides in May, but no differences were significant late in the season. Few leafhoppers were collected during May, but the number of leafhoppers collected on traps rapidly increased and peaked during June. Afterwards, populations decreased and just a few individuals were trapped late in the season. Overall, significantly more leafhoppers were caught on traps hanging from trees of clone 56026 and 55410 than on trees of the other clones. Dispersion of the potato leafhopper changed from being aggregated in May, to being random in August, and also differed among the different clones. Populations tended to aggregate with increases in population numbers. Positive significant autocorrelations were detected at short distances in May, suggesting an aggregated spatial pattern early in the season. Yet, different autocorrelation patterns were detected within each block later in the season. Our results indicate that management practices could be developed to minimise pesticide use by targeting smaller areas with the highest populations at the right time of the season.
Occurrence and distribution of cassava begomoviruses in Kenya
Authors: WERE H K , WINTER S , MAISS E
Published: July 2006

A survey for cassava mosaic disease (CMD) was conducted in Kenya, to investigate the factors contributing to the generally increased incidence and severity of CMD in the cassava growing regions and to study the distribution of the disease's causal begomoviruses, African cassava mosaic virus (ACMV) and East African cassava mosaic virus (EACMV) and their strains. Special emphasis was given to the occurrence of the destructive recombinant Uganda variant strain of EACMV (EACMV‐UG2). Samples from 91 farmers' fields in the main cassava‐growing areas of coastal and western Kenya were collected and subjected to ELISA and PCR for detection and typing of the begomoviruses present. CMD incidence was highest in western Kenya (80–100%) and lowest in the Coast province (25–50%). In Western and Nyanza provinces, 52% of the samples tested contained EACMV‐UG2, 22% ACMV and 17% contained both ACMV and EACMV‐UG2. EACMV was found in four cases at different sites. In cassava samples from the coast province, only EACMV with DNA‐A sequences similar to EACMV strains present in Kenya and Tanzania was found. East African cassava mosaic Zanzibar virus (EACMZV) was present in several farms in the Kilifi district. In 15% of all cassava samples with CMD symptoms, flexuous, filamentous virus‐like particles were also found, providing evidence for a more complex virus situation in cassava grown at the Kenyan coast. In western Kenya, where intense cassava cultivation takes place, CMD is rampant and EACMV‐UG2 was found in mixed virus infections with ACMV driving the epidemics. In coastal areas, where farms are scattered and in isolation, EACMV is endemic, however, with a lower disease incidence and with a limited impact to cassava production.
Patterns of spread of Tomato spotted wilt virus in field crops of lettuce and pepper: spatial dynamics and validation of control measures
Authors: COUTTS B A , THOMAS‐CARROLL M L , JONES R A C
Published: July 2006

Patterns of spread of Tomato spotted wilt virus (TSWV) were examined in lettuce and pepper plantings into which thrips vectors spread the virus from external virus sources. These plantings were: 1) seven separate field trials into which TSWV ‘infector’ plants of tomato were introduced alongside or near to plantings of lettuce or pepper, and 2) three commercial lettuce plantings into which spread from nearby external infection sources was occurring naturally. The vector thrips species were Frankliniella occidentalis, F. schnitzel and Thrips tabaci, at least two of which were always present. Spatial data for plants with TSWV infection collected at different stages in the growing period were assessed by plotting gradients of infection, and using Spatial Analysis by Distance IndicEs (SADIE) and maps of spatial pattern. Despite the persistent nature of TSWV transmission by thrips vectors, in both lettuce and pepper plantings there was a steep decline in TSWV incidence with distance from external infection sources that were alongside them. The extent of clustering increased over time and was greatest closest to the source. The relationship between percentage infection and assessment date suggested that spread was predominantly monocyclic with only limited polycyclic spread. Development of isolated clusters of infected plants distant from TSWV sources within both crops was consistent with only limited polycyclic spread. Spread to lettuce was greater downwind than upwind of virus source, with magnitude and proximity of source determining the amount of spread. When 15 m wide fallow or non‐host (cabbage) barriers separated TSWV sources from lettuce plantings, spread was slower and there was much less clustering with the latter. In commercial lettuce plantings, spread was favoured by TSWV movement within successive side‐by‐side plantings. The spatial data from the diverse scenarios examined enabled recommendations to be made over ‘safe’ planting distances between external infection sources of different magnitudes and susceptible crops that were short‐lived (e.g. lettuce) or long‐lived (e.g. pepper). They also helped validate the inclusion of isolation and ‘safe’ planting distances, planting upwind, prompt removal of virus sources, avoidance of side‐by‐side plantings, and deploying intervening non‐host barrier crops as control measures within an integrated disease management strategy for TSWV in field vegetable crops.
The effects of banana weevil, Cosmopolites sordidus, damage on highland banana growth, yield and stand duration in Uganda
Authors: GOLD C S , KAGEZI G H , NIGHT G , RAGAMA P E
Published: July 2006

A trial to determine yield losses in East African highland banana (cv. Atwalira) to banana weevil was run between 1994 and 2001 at the International Institute of Tropical Agriculture's Sendusu Farm in Namulonge, Uganda. Banana weevil adults were released into weevil‐infestation plots, while weevils were excluded from controls by trapping and later application of chlorpyrifos. Weevil migration and reproduction in control plots reduced treatment differences in damage during the first 3 yr. Thereafter, weevil damage was heavy in infested plots and negligible in controls. High levels of weevil attack resulted in reduced bunch weights, plant losses, mat disappearance and fewer harvested bunches, with estimated yield losses averaging 42% over the final 4 yr of the trial. The data confirm the importance of banana weevil as an important production constraint of highland banana and support farmer reports that banana weevil attack contributes to shortened plantation life.
Influences of preceding cover crops on slug damage and biological control using Phasmarhabditis hermaphrodita
Authors: VERNAVÁ M N , PHILLIPS‐AALTEN P M , HUGHES L A , ROWCLIFFE H , WILTSHIRE C W , GLEN D M
Published: July 2006

In a replicated field experiment, ryegrass, vetch and red clover were grown or the soil was kept bare over a 2–month period in summer to compare the effects of these treatments on slug damage to the following crop (Chinese cabbage) and on the efficacy of nematodes (Phasmarhabditis hermaphrodita) applied as biological control agents to the soil at planting time to protect this crop. Slug damage was significantly (c. two times) greater after red clover or vetch than after ryegrass. Damage on plots without cover crop was intermediate and not significantly different from either extreme. Slug damage was reduced by about one‐third by the nematode treatment. The preceding cover crop did not influence nematode efficacy. Numbers of slugs on harvested plants (mainly Deroceras reticulatum and Deroceras panormitanum) were influenced by an interaction between cover crop and nematode treatment. On subplots without nematodes, more slugs were recorded with than without a preceding cover crop. No such differences were found on nematode‐treated subplots. Soil samples were collected at intervals from 0–99 days after nematode treatment to monitor nematode survival and infectivity in bioassays with D. reticulatum. No significant effects of cover crops were detected in bioassays. Moreover, there were no significant effects of nematodes on slug survival. Their effects on slug food consumption were mostly insignificant and any effects were transient and not consistent. However, significantly more slug cadavers contained nematodes when slugs were exposed to nematode‐treated soil. The implications of these results are discussed.
Comparison of Groundnut bud necrosis virus isolates based on movement protein (NSm) gene sequences
Authors: AKRAM MOHD , JAIN R K , CHAUDHARY VIKAS , AHLAWAT Y S , KHURANA S M PAUL
Published: July 2006

The nucleotide and amino acid sequences of the movement protein (NSm) genes of five isolates of Groundnut bud necrosis virus (GBNV) originating from different hosts and parts of India such as cowpea and tomato from Kerala, groundnut from Tamil Nadu, and potato from Madhya Pradesh and Rajasthan were determined and compared to the known NSm sequences. Sequence analysis revealed that the NSm genes of GBNV isolates were identical in length (924 bp encoding 307 amino acids). GBNV isolates shared maximum identity (98–100%) at amino acid levels with GBNV‐Type isolate, while 82–83% and 34–65% amino acid sequence identities were observed with Watermelon silver mottle virus and other Tospoviruses respectively. The NSm genes among GBNV isolates originating from different hosts and locations appeared highly conserved (93–100%), suggesting their common origin.
Molecular genetic variation and geographical structuring in Fusarium graminearum
Authors: MISHRA PRASHANT K , TEWARI JALPA P , CLEAR RANDALL M , TURKINGTON T KELLY
Published: July 2006

Inter‐simple sequence repeat markers were employed to study the genetic structure of Fusarium graminearum populations collected from three Canadian provinces. Our study suggested high genetic diversity and frequent gene flow among population samples analysed. The analysis of molecular variance indicated that most of the gene diversity (91.78% to 97.23%) was distributed within populations. Frequent gene flow among the western prairie provinces and cluster analysis results indicated that the population sample from Alberta was closer to Saskatchewan than Manitoba, which could be the result of movement of the pathogen via infected grain or through wind‐borne ascospore dispersal. Analysis of multilocus associations showed that all populations were in linkage equilibrium, indicating that sexual recombination is a frequent phenomenon in F. graminearum populations from western Canada.
Efficacy of hot water drenches of Anthurium andraeanum plants against the burrowing nematode Radopholus similis and plant thermotolerance
Authors: TSANG MARCEL M C , KARA A H , SIPES B S
Published: July 2006

Hot‐water drench treatments were evaluated for disinfesting roots of potted anthurium Anthurium andraeanum of the burrowing nematode Radopholus similis. A continuous drench of roots and media in pots with 50°C water for 5 to 20 min eliminated or reduced nematode populations to < 1 g−1 of dry root. A second hot water drench, 2 months after the first drenching, tended to increase the efficacy of the heat treatment. A few survivors persisted in the roots and/or stems of a few plants 2 to 4 months after heat treatment. Non‐treatment of the shoots and possible migration from stem to root tissues are probable causes of nematode survival. Drenching potting media and roots in pot were as effective against R. similis in the roots as hot water dipping bare‐rooted plants. Plant response to hot‐water drenching varied among cultivars, but most exhibited tolerance to the heat treatments. Visual inspection of the plants showed little difference between treated and untreated plants in the heat tolerant cultivars. However, all heat‐treated ‘Marian Seefurth’ plants, especially hot water‐dipped bare‐rooted plants, appeared to suffer some degree of growth reduction as measured by lower root and stem dry weights when compared to untreated plants 3 months after treatment. Conditioning anthurium plants with hot water or hot air prior to hot water drenching did not benefit plant quality when compared to unconditioned, heat‐treated plants.
Flight activity of the damson–hop aphid, Phorodon humuli.
Authors: Campbell C.A.M. , Muir R.C.
Published: July 2006

Flight activity of Phorodon humuli was monitored using suction traps, laboratory studies and mark and recapture experiments. Emigrants were trapped as they flew from a Myrobalan (Prunus cerasifera) hedge and among dwarf hops (Humulus lupulus). Daily flight curves were bimodal with 69% and 38% of emigrants caught in the morning peak near Myrobalan and among hops, respectively. The median period of flight activity was from 2 h after sunrise until 30 min before sunset. The lower temperature for flight was 13.5°C in the field and 14.9°C for take off in the laboratory. Variations in wind speed had little effect on flight activity explaining <2.5% of the total variance among insect counts. The percentage of emigrants on hop declined exponentially with time. The relationship, y= 10.9(±2.0) + 64.3(±2.3) × 0.92(±0.01)t where t = daylight hours (standard error in parentheses), explained 98.3% of the variance. Hence, 62% of new arrivals flew within 1 day of arrival and 79% within 2 days. Similar numbers arrived as departed at 08:30, 10:30 and 12:30 h, but at 14:30 h twice as many arrived than departed and at 16:30 h, the accumulation was threefold. Daily flight curves of return migrants and males leaving hop were bimodal with 70% and 80%, respectively, trapped in the earlier peak. In the field, the median lower temperature for flight was 13.2°C for return migrants and a nonsignificantly different 12.8°C for males. The mean temperature for take off by return migrants was 15.7°C in the laboratory.
Patterns of spread of Carrot virus Y in carrot plantings and validation of control measures
Authors: Jones R.A.C. , Smith L.J. , Gajda B.E. , Latham L.J.
Published: July 2006

Patterns of spread of Carrot virus Y (CarVY) were examined in carrot plantings in Western Australia into which naturally occurring aphid vectors spread the virus from external infection sources. Within three field trials, CarVY ‘infector’ plants were introduced between or at different distances from carrot plantings. There was a marked decline in CarVY incidence over distance from adjacent introduced infection sources. Clusters of infected plants that enlarged and coalesced were concentrated next to such sources but, later, isolated, expanding clusters formed further away. With a small external virus source, initial spread into the edge of a planting was less extensive than with a larger source. When 15‐m‐wide fallow areas separated a CarVY source from carrot plots, spread was much slower than when the separation was only 1 m; it was also slower upwind than downwind of this source. The data collected help validate the inclusion of isolation and ‘safe’ planting distances, intervening fallow, planting upwind, prompt removal of virus sources, avoidance of side‐by‐side plantings and manipulation of planting date within an integrated disease management strategy for CarVY in carrots.
A spatio‐temporal analysis of a New Zealand flatworn (Arthurdendyus triangulatus) population in western Scotland
Authors: Boag B. , Deeks L. , Orr A. , Neilson R.
Published: July 2006

The New Zealand flatworm (Arthurdendyus triangulatus), which is an obligate predator of native earthworms, is an alien species to the British Isles and is widely distributed in Scotland. What little is known about its biology under field conditions is mainly from Northern Ireland. Samples taken from single sampling dates have shownA. triangulatusto have an aggregated distribution. To determine the spatio‐temporal distribution ofA. triangulatus, a grass field in western Scotland was intensively sampled over a 16‐month period. Data indicate an increase in flatworm numbers and seasonal trends in body weight, the appearance of egg capsules and hatchlings. Results also showed that spatially, the flatworms were aggregated, but this was a transient phenomenon over the period of the experiment. The distribution of egg capsules in the study area was strongly aggregated and related to the appearance of hatchlings. Flatworms may aggregate in areas where soil moisture is optimal for the survival of the New Zealand flatworm.
Evaluation of microcapsule trunk injections for the control of apple scab and powdery mildew
Authors: Percival G.C. , Boyle S.
Published: July 2006

A 3‐year field trial was conducted using established apple cv. Crown Gold and English oak (Quercus robur L.) to assess the efficacy of eight fungicides applied via microcapsule trunk injection against the foliar pathogens apple scab (Venturia inaequalis) and powdery mildew (Phyllactinia sp). In both apple cv. Crown Gold and English oak, the fungicide myclobutanil was not taken up when microcapsules were inserted into the tree vascular system at the root flare. Disease severity in injected trees, excluding myclobutanil, was lower over the following two growing seasons compared to water‐injected controls indicating seven of the eight fungicides used in this study provided a significant degree of protection against scab and powdery mildew infection. A difference in the magnitude of pathogen control achieved was recorded between fungicides. Of the fungicides tested, penconazole, pyrifenox and carbendazim significantly reduced disease severity and significantly increased leaf chlorophyll (Fv/Fm) and SPAD values as a measure of tree vitality and chlorophyll content, respectively, in both apple cv. Crown Gold and English oak over two growing seasons after microcapsule injection. Based on the results of this investigation, it is suggested that these three fungicides be used in preference to thiabendazole, fosetyl‐aluminium, triadimefon and propiconazole for the control of apple scab and powdery mildew where outbreaks of these foliar pathogens are problematic.
Bark Consumption by the Painted Ringtail (Pseudochirulus forbesi larvatus) in Papua New Guinea1
Authors: Stephens Suzette A. , Salas Leonardo A. , Dierenfeld Ellen S.
Published: July 2006

We documented bark consumption by painted ringtails (Pseudochirulus forbesi) and other arboreal marsupials at Mt. Stolle, Papua New Guinea. Evidence consisted of scratch marks on the boles of trees in conjunction with the removal of all moss and direct sightings of animals eating bark. Only 43 trees ≥10 cm diameter at breast height (DBH) of 19 species showed signs of consumption at the study site; five of these species were confirmed by direct sighting to be consumed by painted ringtails. We sought to determine if bark of these trees contained important dietary minerals. Analyses showed that calcium and potassium, individually and combined, were significantly more abundant in eaten versus uneaten trees of the same species. On average, eaten trees showed 4.7 and 2.2 times the amount of these minerals, respectively, as found in uneaten trees. Adult males were more likely than adult females or juvenile males to be captured at eaten trees than away from them. Two species of Syzygium and one species of Sloanea were highly selected for bark consumption, but not all trees of a species were eaten; rather, particular individuals of these species were preferred. We conclude that bark appears to be an important source of calcium and potassium, and speculate on the relationship between the limited availability of these special trees and the social behavior of painted ringtails.
Physicochemical characteristics and amino acid profile of chickpea cultivars grown in Pakistan
Authors: Iqbal Amjad , Ateeq Nadia , Khalil Iqtidar A. , Perveen Sajida , Saleemullah Saleem
Published: July 2006

The proximate mineral composition, amino acid profile and physicochemical characteristics of three new chickpea cultivars (two Desi: NIFA‐88, NIFA‐95, and one Kabuli: Hassan‐2k) grown in the North West Frontier Province of Pakistan were studied, in order to assess their role in human nutrition. It was found that chickpea is a rich source of protein and minerals. The protein content (22.89–24.82%) of chickpea was much higher than that of cereals (wheat and maize), and comparable to other legumes. Mineral composition of chickpea cultivars showed that they contribute sufficient amount of Ca, P, K, Cu, Zn and Mg in human diets to meet the recommended dietary allowance. The essential amino acid leucine (8.7% of protein) was found in highest concentration, followed by arginine (8.3% of protein) and lysine (7.2% of protein) in the chickpea cultivars. In terms of physical characteristics, more variability was observed in seed size and seed volume than in hydration and swelling capacities, cooking time and hydration and swelling indices. Phytic acid content ranged from 132.3 to 170.7 mg/100 g of dried sample. The higher amount was recorded in Desi than in the Kabuli cultivar of chickpea. It was concluded that chickpea may improve the nutritional value of a cereal‐based diet.
CONTAMINATION OF GRAINS BY MYCOTOXIN‐PRODUCING MOLDS AND MYCOTOXINS AND CONTROL BY GAMMA IRRADIATION
Authors: AZIZ NAGY H. , MATTAR ZAKARIA AHMED , MAHROUS SOUZAN ROUSDY
Published: July 2006

Ninety random grain samples were collected and analyzed for mycotoxins, and the effect of gamma irradiation on the production of mycotoxins in grains was studied. Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium, Alternaria, Scopulariopsis and Cladosporium were the most common fungal genera isolated from grains. Aspergillus flavus, Aspergillus niger, Aspergillus candidus, Aspergillus ochraceus, Penicillium citrinum, Penicillium expansum, Penicillium citreonigrum, Penicillium purpurogenum, Penicillium griseofulvum and Penicillium verrucosumwere the most common Aspergillus and Penicillium species in grains. Out of 120 Aspergillus and Penicillium isolates, 80 were mycotoxin producers. Analysis of grains revealed the occurrence of aflatoxin B1 ochratoxin A, cycolopiazonic acid and citrinin. Of the 90 samples, 67 were positive for one or more mycotoxin. Irradiation of grains at dose of 2.0 and 4.0 kGy decreased significantly the total fungal counts compared with unirradiated controls. After 100 days of storage at room temperature, the unirradiated grains were contaminated with high concentrations of mycotoxins as compared with irradiated 4.0‐kGy samples. Mycotoxin production in grains decreased with increasing irradiation doses and was not detected at 6.0 kGy over 100 days of storage.
EFFECT OF STORAGE TEMPERATURE ON THE GROWTH OF LISTERIA MONOCYTOGENES ON QUESO BLANCO SLICES*
Authors: UHLICH GAYLEN A. , LUCHANSKY JOHN B. , TAMPLIN MARK L. , MOLINA‐CORRAL FRANCISCO J. , ANANDAN SHIVANTHI , PORTO‐FETT ANNA C.S.
Published: July 2006

A five‐strain cocktail of Listeria monocytogenes (104 cfu/mL) was inoculated onto individual vacuum‐packaged slices (ca. 50 g each) of a commercial, Hispanic‐style cheese, that being Queso Blanco. Growth was determined at appropriate intervals during storage at 5, 10, 15, 20 and 25C. In general, as the incubation temperature increased, a shorter lag phase duration (LPD) and a faster growth rate (GR) were observed. The LPD values at 5, 10, 15, 20 and 25C were 65.3, 19.9, 2.1, 8.4 and 11.4 h, respectively. The GR values were 0.011, 0.036, 0.061, 0.090 and 0.099 log cfu/h at 5, 10, 15, 20 and 25C, respectively. There were no statistical differences in LPD at 10, 15, 20 and 25C. However, the LPD during growth at 5C was statistically (P ≤ 0.05) longer than at all other temperatures. The GR values at 20 and 25C were not significantly different from each other, whereas the GR values at 5, 10 and 15C were significantly different from each other as well as from the GR at 20 and 25C (P ≤ 0.05). The maximum population density (MPD) showed relatively little variation over the range of storage temperatures tested, with an average of 8.38 log cfu/g (SD = 0.33). The results of this study indicate that not even the lowest trial temperature of 5C prevented growth over time of the inoculated L. monocytogenes on this sliced product, and that proper storage and handling procedures are required to prevent the bacterium from contaminating the product and/or to control its growth.
INVESTIGATION OF INHIBITORY EFFECTS OF SEVERAL COMBINATIONS OF SODIUM SALTS ON THE GROWTH OF LISTERIA MONOCYTOGENES AND SALMONELLA ENTERICA SEROTYPE ENTERITIDIS IN MINCED BEEF
Authors: SERDENGECTI NEJLA , YILDIRIM IBRAHIM , GOKOGLU NALAN
Published: July 2006

Inhibition effects of several combinations of sodium lactate (SL), sodium acetate, sodium diacetate (SDA) on the growth of Listeria monocytogenes and Salmonella enterica serotype Enteritidis were investigated in minced beef. The samples inoculated with 4.60 log cfu/g of Salmonella enteritidis and 4.70 log cfu/g of L. monocytogenes were treated with sodium salts and their combinations and stored at 4C. Sodium salts decreased the growth rate of S. enterica serotype Enteritidis. Combinations of the salts were bactericidal to S. enterica serotype Enteritidis but the growth of L. monocytogenes was delayed only by using the combination of 2.5% SL and 0.2% SDA.
KILLER WHALES, WHALING, AND SEQUENTIAL MEGAFAUNAL COLLAPSE IN THE NORTH PACIFIC: A COMPARATIVE ANALYSIS OF THE DYNAMICS OF MARINE MAMMALS IN ALASKA AND BRITISH COLUMBIA FOLLOWING COMMERCIAL WHALING
Authors: Trites Andrew W. , Deecke Volker B. , Gregr Edward J. , Ford John K.B. , Olesiuk Peter F.
Published: July 2006

Abstract

The hypothesis that commercial whaling caused a sequential megafaunal collapse in the North Pacific Ocean by forcing killer whales to eat progressively smaller species of marine mammals is not supported by what is known about the biology of large whales, the ecology of killer whales, and the patterns of ecosystem change that took place in Alaska, British Columbia, and elsewhere in the world following whaling. A comparative analysis shows that populations of seals, sea lions, and sea otters increased in British Columbia following commercial whaling, unlike the declines noted in the Gulf of Alaska and Aleutian Islands. The declines of seals and sea lions that began in western Alaska around 1977 were mirrored by increases in numbers of these species in British Columbia. A more likely explanation is that the seal and sea lion declines and other ecosystem changes in Alaska stem from a major oceanic regime shift that occurred in 1977. Killer whales are unquestionably a significant predator of seals, sea lions, and sea otters—but not because of commercial whaling.
Herbivory differentially alters plant litter dynamics of evergreen and deciduous trees
Authors: Chapman Samantha K. , Whitham Thomas G. , Powell Merriam
Published: July 2006

Here we propose that herbivore‐induced changes in leaf litter quality can modify aboveground litterfall dynamics differentially in evergreen and deciduous trees. Because aboveground plant litterfall is an important source of nutrients in terrestrial ecosystems, any factor that alters plant litter quality can have large “afterlife” effects on the decomposition rate of that litter and the subsequent rate of nutrient release. Two contrasting patterns emerge from the literature and are corroborated by our two experimental case studies. First, in evergreens, herbivory commonly results in premature leaf abscission, improved litter “quality” and an acceleration of litter decomposition. Second, in deciduous trees, herbivory commonly results in the induction of secondary compounds that decelerates decomposition. We argue that these broad patterns reflect predictable differential responses to herbivores that can have important consequences for terrestrial nutrient cycling and productivity and that warrant more attention in the literature.
The effects of plant quality on caterpillar growth and defense against natural enemies
Authors: D. Coley P. , L. Bateman M. , A. Kursar T.
Published: July 2006

A survey of 85 species of Lepidoptera feeding on 40 hosts on Barro Colorado Island, Panama showed that growth and defensive traits of caterpillars were correlated with the nutritional and defensive traits of their hosts. Growth rates were faster on young than mature leaves, reflecting the higher nitrogen and water content of the former. Growth was also positively correlated with leaf expansion rate, partially because of higher nitrogen and water contents of fast‐expanding young leaves. Specialists grew faster than generalists, but both responded positively to nutritional quality. There was no effect of lepidopteran family on growth. In analyses where the effects of nitrogen and water were removed, the residuals for growth rate were greater for young than for mature leaves and were positively correlated with expansion rates of young leaves. This suggests that traits other than nutrition were also important. As young, expanding leaves cannot use toughness as a defense, one possible explanation for the differences in growth is differences in chemical defenses. Growth rate residuals for both specialists and generalists were higher for the more poorly defended fast‐expanders, but the effect was greatest for generalists, perhaps because generalists were more sensitive to secondary metabolites. We predicted that slow growth for caterpillars would increase their risk to natural enemies and would select for higher defenses. Generalists had more defensive traits than specialists and were less preferred in feeding trials with ants. Similarly, species feeding on mature leaves were the most defended and those feeding on fast‐expanding young leaves were the least defended and most preferred by ants. Thus the effects of plant secondary metabolites and nutrients dictate herbivore growth rates, which in turn influence their susceptibility to the third trophic level and the importance of defenses.
Larch‐ and pine‐feeding host races of the larch bud moth (Zeiraphera diniana) have cyclic and synchronous population fluctuations
Authors: Dormont Laurent , Baltensweiler Werner , Choquet Rémi , Roques Alain
Published: July 2006

Population cycles of many forest‐defoliating insects often show synchronous fluctuations at both intra‐specific (spatial synchrony) and inter‐specific levels. However, population dynamics of different host‐associated biotypes of the same species, such as those of the larch budmoth (LBM), Zeiraphera diniana (Lepidoptera: Tortricidae), have never been compared. This species causes extensive defoliation of larch forests every 8 to 9 years in the Alps, but it consists of two genetically‐differentiated host races, the first one developing on European larch, Larix decidua, and the other one developing on Swiss stone pine, Pinus cembra. The dynamics of Zeiraphera populations have been extensively studied on larch, whereas little is known about larval density and possible population fluctuations on sympatric pines. A larval census on Swiss stone pine was conducted in the Swiss Alps intermittently between 1958 to 2004 and in the French Alps from 1992 to 2004. Population density of Zeiraphera on pine varied up to 5000‐fold and showed periodic oscillations, with five peaks in Switzerland and one in France. Because the feeding activity of the pine race is restricted to the elongating shoot of the current year, no conspicuous defoliation of pine trees was noted during years of high larval densities. Zeiraphera populations on pine oscillated in significant synchrony with larch‐associated populations, and peak densities were observed either the same year or shifted by±one year. Our results did not allow any explanation for cyclic fluctuations of LBM on pine, but the synchrony with the larch race's cycle suggests that studies on genetics as well as on parasitism should be intensified.
Natural and Forced Conjugate Heat Transfer in Complex Geometries on Cartesian Adapted Grids
Authors: Iaccarino Gianluca , Moreau Stéphane
Published: July 2006

The Cartesian incompressible RANS solver with immersed boundaries, IBRANS, recently developed at Stanford, has been extended to include conjugate heat transfer modeling and used for the simulation of the electrical motor of an automotive engine cooling fan system. Such applications are particularly challenging, as they involve very complex geometries with tight tolerances and rotating parts. The new conjugate heat transfer capability of IBRANS has been verified on natural and forced convection flows. The former involves flows in enclosures around a sphere and electronic chips. The latter focuses on heated cylinders for Reynolds numbers covering flow regimes ranging for a steady laminar flow to unsteady turbulent flows. Excellent agreement is achieved with similar simulations with a conventional body-fitted solver (FLUENT 6.1) using equivalent turbulent models. First three-dimensional simulations of the flow and heat transfer within the complete electrical motor are presented. The numerical predictions of the pressure drop through the motor as a function of flow rate agree very well with the measured data over the complete operating range.
Phase Distribution in the Cap Bubble Regime in a Duct
Authors: Lopez de Bertodano Martin , Sun Xiaodong , Ishii Mamoru , Ulke Asim
Published: July 2006

The lateral phase distribution in the cap-bubbly regime was analyzed with a three-dimensional three-field two-fluid computational fluid dynamics (CFD) model based on the turbulence model for bubbly flows developed by Lopez de Bertodano et al. [1994, “Phase Distribution in Bubbly Two-Phase Flow in Vertical Ducts,” Int. J. Multiphase Flow, 20(5), pp. 805–818]. The turbulent diffusion of the bubbles is the dominant phase distribution mechanism. A new analytic result is presented to support the development of the model for the bubble induced turbulent diffusion force. New experimental data obtained by Sun et al. [2005, “Interfacial Structure in an Air-Water Planar Bubble Jet,” Exp. Fluids, 38(4), pp. 426–439] with the state-of-the-art four-sensor miniature conductivity probe in a vertical duct is used to validate the three-field two-fluid model CFD simulations.
Numerical and Experimental Investigation on the Flow Induced Oscillations of a Single-Blade Pump Impeller
Authors: Benra F.-K.
Published: July 2006

This contribution is addressed to the periodically unsteady flow forces of a single-blade sewage water pump, which affect the impeller and produce radial deflections of the pump shaft. The hydrodynamic excitation forces were calculated from the time dependent flow field, which was computed by numerical simulation of the three-dimensional, viscous, time-dependent flow in the pump. A commercial computer code was used to determine the time accurate Reynolds averaged Navier-Stokes equations. The transient radial flow forces at all time steps for a complete impeller revolution affect the rotor of the single-blade pump and stimulate it to strong oscillations. To determine the influence of the vibration stimulation forces on the dynamic behavior of the pump rotor, an investigation of the rotor’s structural dynamics was accomplished. A dynamic time analysis for the pump rotor provided the dynamic answer from the structural model of the rotor under the influence of the flow forces. The hydrodynamic forces, which were calculated before, were defined as external forces and applied as the load on the rotor. The resulting impeller deflections were calculated by a transient analysis of the pump rotor system using the commercial finite element method software PROMECHANICA. To verify the results obtained by standard numerical methods, the radial deflections of the impeller of a commercial sewage water pump, which has been investigated numerical in advance, were measured for the horizontal and for the vertical coordinate direction by proximity sensors. The measured data were compared to the computed amounts for a wide range of pump operation. The results show a good agreement for a strong part of an impeller revolution for all investigated operating points. The simultaneous measurement of vibration accelerations at the outer side of the pump casing showed the effects of the time-dependent flow, which produce hydrodynamic forces acting at the impeller of the pump and stimulating it to strong oscillations.
Optimal Yaw Regulation and Trajectory Control of Biorobotic AUV Using Mechanical Fins Based on CFD Parametrization
Authors: Narasimhan Mukund , Dong Haibo , Mittal Rajat , Singh Sahjendra N.
Published: July 2006

This paper treats the question of control of a biorobotic autonomous undersea vehicle (BAUV) in the yaw plane using a biomimetic mechanism resembling the pectoral fins of fish. These fins are assumed to undergo a combined sway-yaw motion and the bias angle is treated as a control input, which is varied in time to accomplish the maneuver in the yaw-plane. The forces and moments produced by the flapping foil are parametrized using computational fluid dynamics. A finite-difference-based, Cartesian grid immersed boundary solver is used to simulate flow past the flapping foils. The periodic forces and moments are expanded as a Fourier series and a discrete-time model of the BAUV is developed for the purpose of control. An optimal control system for the set point control of the yaw angle and an inverse control law for the tracking of time-varying yaw angle trajectories are designed. Simulation results show that in the closed-loop system, the yaw angle follows commanded sinusoidal trajectories and the segments of the intersample yaw trajectory remain close to the discrete-time reference trajectory. It is also found that the fins suitably located near the center of mass of the vehicle provide better maneuverability.
Modeling of Laminar Flows in Rough-Wall Microchannels
Authors: Bavière R. , Gamrat G. , Favre-Marinet M. , Le Person S.
Published: July 2006

Numerical modeling and analytical approach were used to compute laminar flows in rough-wall microchannels. Both models considered the same arrangements of rectangular prism rough elements in periodical arrays. The numerical results confirmed that the flow is independent of the Reynolds number in the range 1–200. The analytical model needs only one constant for most geometrical arrangements. It compares well with the numerical results. Moreover, both models are consistent with experimental data. They show that the rough elements drag is mainly responsible for the pressure drop across the channel in the upper part of the relative roughness range.
Blade Angle Effects on the Flow in a Tank Agitated by the Pitched-Blade Turbine
Authors: Tsui Yeng-Yung , Chou Jian-Ren , Hu Yu-Chang
Published: July 2006

This paper presents a study of the influence of the blade angle on the flow in a tank stirred by the pitched-blade turbine. The flow induced by the pitched-blade turbine is usually described as an axial type with a principal ring vortex dominating the flow structure. However, it is known that as the blade becomes vertical, i.e., as the pitch angle of the blade becomes 90deg, the flow is of the radial type, with two main ring vortices occupying the tank. Thus, a transition of flow type must take place when the blade angle is varied. This motivates the current study. A computational method was developed, which incorporates the unstructured grid technique to deal with the complex geometry in the tank. Multiframe of reference was employed to handle the rotation of the impeller. The results show that the transition from the axial type to the redial type is not progressive, but occurs all of a sudden at a particular angle, depending on the configuration. This critical angle decreases as the off-bottom clearance and the impeller size are increased. Its influences on the flow angle of the discharge stream, the power requirement, the induced flow rate through the impeller, and the pumping efficiency are discussed. The mechanism to cause the sudden change of flow type is addressed through observing the flow on the surface of the turbine blade.
Bifurcation Characteristics of Flows in Rectangular Sudden Expansion Channels
Authors: Battaglia Francine , Papadopoulos George
Published: July 2006

The effect of three dimensionality on low Reynolds number flows past a symmetric sudden expansion in a channel was investigated. The geometric expansion ratio in the current study was 2:1 and the aspect ratio was 6:1. Both experimental velocity measurements and two- and three-dimensional simulations for the flow along the centerplane of the rectangular duct are presented for Reynolds numbers in the range of 150 to 600. Comparison of the two-dimensional simulations with the experiments revealed that the simulations failed to capture completely the total expansion effect on the flow, which is influenced by both geometric and hydrodynamic effects. To properly do so requires the definition of an effective expansion ratio, which is the ratio of the downstream and upstream hydraulic diameters and is therefore a function of both the expansion and aspect ratios. When two-dimensional simulations were performed using the effective expansion ratio, the new results agreed well with the three-dimensional simulations and the experiments. Furthermore, in the range of Reynolds numbers investigated, the laminar flow through the expansion underwent a symmetry-breaking bifurcation. The critical Reynolds number evaluated from the experiments and the simulations were compared to other values reported in the literature. Overall, side-wall proximity was found to enhance flow stability, thus sustaining laminar flow symmetry to higher Reynolds numbers. Last, and most important, when the logarithm of the critical Reynolds number was plotted against the reciprocal of the effective expansion ratio, a linear trend emerged that uniquely captured the bifurcation dynamics of all symmetric double-sided planar expansions.
Identification of Transition to Turbulence in a Highly Accelerated Start-Up Pipe Flow
Authors: Koppel T. , Ainola L.
Published: July 2006

The transition from a laminar to a turbulent flow in highly accelerated start-up pipe flows is described. In these flows, turbulence springs up simultaneously over the entire length of the pipe near the wall. The unsteady boundary layer in the pipe was analyzed theoretically with the Laplace transformation method and the asymptotic method for small values of time. From the experimental results available, relationships between the flow parameters and the transition time were derived. These relationships are characterized by the analytical forms. A physical explanation for the regularities in the turbulence spring-up time is proposed.
Bubble Effect on the Structures of Weakly Turbulent Couette Taylor Flow
Authors: Mehel Amine , Gabillet Celine , Djeridi Henda
Published: July 2006

In industrial applications, rotating flows have been recognized to enhance mixing and transfer properties. Moreover, bubbly flows are also used to improve transfers. Therefore, it is interesting to study the effects of the dispersed phase on the structure of a Couette Taylor flow. Experiments are conducted for the quasi-periodic (Ta=780) and the weakly turbulent (Ta=1000) flow regimes. Bubbles (0.035 times as small as the gap) are generated by agitation of the upper free surface (ventilated flow). Larger bubbles (0.15 times as small as the gap) are generated by injection at the bottom of the apparatus and by applying a pressure drop (gaseous-cavitating flow). Void fraction, bubble size, and velocity, as well as axial and azimuthal velocity components of the liquid are investigated. The bubble location in the gap clearly depends on the bubble size. For α>0.1%, there is evidence of bubble-induced modifications of axial transfers and wall shear stress, the observed trends being different according to the bubble location in the gap.