bluuebunny/crossref_metadata_2025 huggingface dataset:
Water uptake dynamics, photosynthesis and water use efficiency in field‐grown Medicago arborea and Medicago citrina under prolonged Mediterranean drought conditions
Authors: LEFI E , MEDRANO H , CIFRE J
Published: July 2006

Drought is the main limiting factor of forage production in semi‐arid areas. Annual variation of soil water availability (SWA), predawn leaf water potential (Ψpd), stomatal conductance (g), photosynthesis rate (A) and the intrinsic water use efficiency (A/g) were examined under irrigation (control) and rain fed conditions in Palma de Mallorca (Spain) for two Mediterranean shrubs: Medicago arborea (M. arborea), with a wide distribution and Medicago citrina (M. citrina), an endemic species to the Balearic islands. Experimental conditions were typically Mediterranean, with low annual precipitation.

In well‐irrigated plants, SWA and Ψpd were similar for both species throughout the year but higher g was observed in autumn and in spring‐summer. The photosynthesis rate was slightly higher in autumn and spring. Even though photosynthetic activity in M. arborea was higher than in M. citrina in spring, A/g was relatively higher for M. citrina for most of the year due to a lower transpiration rate.

Under rain fed conditions, SWA dropped after February from 70% to 10–20%. Variations in plant water status, g and A were mainly dependent on SWA. Moreover, differences for water extraction and water use efficiency between species were found. Under moderate drought (SWA > 60%), g was more severely reduced than A and Ψpd (October‐March), as a consequence, A/g increased. Stomatal conductance variations for both species were more closely related to soil moisture rather than to leaf water status. Interestingly, M. citrina desiccated the soil more gradually and extracted water at deeper horizons (between 0.5 and 1 m). As a consequence, it maintained relatively higher Ψpdg and A than M. arborea throughout spring. For M. arborea, SWA declined more rapidly and leaf shedding in spring was much more substantial. When subjected to severe and prolonged summer drought (SWA < 50%), all parameters were severely reduced for both species and A had values near zero. Consequently, A/g was low and the senescence of the majority of leaves for M. arborea took place. On the basis of these results, M. citrina exhibits a higher water use efficiency under moderate drought.
Identification of Hordeum spontaneum QTL alleles improving field performance of barley grown under rainfed conditions
Authors: TALAMÉ V , SANGUINETI M C , CHIAPPARINO E , BAHRI H , BEN SALEM M , FORSTER B P , ELLIS R P , RHOUMA S , ZOUMAROU W , WAUGH R , TUBEROSA R
Published: July 2006

Advanced backcross QTL (AB‐QTL) analysis was deployed to identify allelic variation in wild barley (Hordeum vulgare ssp. spontaneum) of value in the improvement of grain yield and other agronomically important traits in barley (Hordeum vulgare ssp. vulgare) grown under conditions of water deficit in Mediterranean countries. A population of 123 double haploid (DH) lines obtained from BC1F2 plants derived from a cross between Barke (European two‐row cultivar) and HOR11508 (wild barley accession) were tested in replicated field trials, under varying conditions of water availability in Italy, Morocco and Tunisia, for seven quantitative traits. Significant QTL effects at one (P 0.001) or more trial sites (P 0.01) were identified for all traits. At 42 (52%) of the 80 putative QTLs identified, the allele increasing a “traits' value” was contributed by H. spontaneum. For example, though the majority (67%) of QTL alleles increasing grain yield were contributed by H. vulgare, H. spontaneum contributed the alleles increasing grain yield at six regions on chromosomes 2H, 3H, 5H and 7H. Among them, two QTLs (associated to Bmac0093 on chromosome 2H and to Bmac0684 on chromosome 5H) were identified in all three locations and had the highest additive effects. The present study shows the validity of deploying AB‐QTL analysis for identifying favourable QTL alleles from wild germplasm and indicates its potential as an enhancement strategy for the genetic improvement of cultivars better adapted to drought‐prone environments.
Effect of salinisation of soil on growth and macro‐ and micro‐nutrient accumulation in seedlings of Acacia catechu (Mimosaceae)
Authors: RAMOLIYA P J , PATEL H M , PANDEY A N
Published: July 2006

The effects of salinisation of soil on Acacia catechu (Mimosaceae) were studied by means of emergence and growth of seedlings and pattern of mineral accumulation. A mixture of chlorides and sulphates of Na, K, Ca and Mg was added to the soil and salinity was maintained at 4.1, 6.3, 8.2,10.1 and 12.2 dSm−1. A negative relationship between proportion of seed germination and salt concentration was obtained. Seedlings did not emerge when soil salinity exceeded 10.1 dSm−1. Results suggested that this tree species is salt tolerant at the seed germination stage. Seedlings survived and grew up to soil salinity of 10.1 dSm−1, which suggests that this species is salt tolerant at the seedling stage too. Elongation of stem and root was retarded by increasing salt stress. Among the tissues, young roots and stem were most tolerant to salt stress and were followed by old roots and leaves, successively. Leaf tissue exhibited maximum reduction in dry mass production in response to increasing salt stress. However, production of young roots and death of old roots were found to be continuous and plants apparently use this process as an avoidance mechanism to remove excess ions and delay onset of ion accumulation in this tissue. This phenomenon, designated “fine root turnover”, is of importance to the mechanisms of salt tolerance. Plants accumulated Na in roots and were able to regulate transfer of Na ions to leaves. Stem tissues were a barrier for translocation of Na from root to leaf. Moreover, K was affected in response to salinity; it rapidly decreased in root tissues with increased salinisation. Nitrogen content decreased in all tissues (leaf, stem and root) in response to low water treatment and salinisation of soil. Phosphorus content significantly decreased, while Ca increased in leaves as soil salinity increased. Changes in tissue and whole plant accumulation patterns of the other elements tested, as well as possible mechanisms for avoidance of Na toxicity in this tree species during salinisation, are discussed.
Identification and distribution of viruses infecting sweet potato in Kenya
Authors: ATEKA E M , NJERU R W , KIBARU A G , KIMENJU J W , BARG E , GIBSON R W , VETTEN H J
Published: July 2006

Four hundred and forty‐eight symptomatic and 638 asymptomatic samples were collected from sweet potato fields throughout Kenya and analysed serologically using antibodies to Sweet potato feathery mottle virus (SPFMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato mild mottle virus (SPMMV), Cucumber mosaic virus (CMV), Sweet potato chlorotic fleck virus (SPCFV), Sweet potato latent virus (SwPLV), Sweet potato caulimo‐like virus (SPCaLV), Sweet potato mild speckling virus (SPMSV) and C‐6 virus in enzyme‐linked immunosorbent assays (ELISA). Only SPFMV, SPMMV, SPCSV, and SPCFV were detected. Ninety‐two percent and 25% of the symptomatic and asymptomatic plants respectively tested positive for at least one of these viruses. Virus‐infected plants were collected from 89% of the fields. SPFMV was the most common and the most widespread, detected in 74% of the symptomatic plants and 86% of fields surveyed. SPCSV was also very common, being detected in 38% of the symptomatic plants and in 50% of the fields surveyed. SPMMV and SPCFV were detected in only 11% and 3% of the symptomatic plant samples respectively. Eight different combinations of these four viruses were found in individual plants. The combination SPFMV and SPCSV was the most common, observed in 22% of symptomatic plants. Virus combinations were rare in the asymptomatic plants tested. Incidence of virus infection was highest (18%) in Kisii district of Nyanza province and lowest (1%) in Kilifi and Malindi districts of Coast province.
Plant pathogen diagnostics: immunological and nucleic acid‐based approaches
Authors: WARD ELAINE , FOSTER SIMON J , FRAAIJE BART A , MCCARTNEY H ALASTAIR
Published: July 2006

Accurate disease diagnosis and precise identification of any pathogens involved is an essential prerequisite for understanding plant diseases and controlling them effectively. Traditional methods of identifying plant pathogens can be slow and inconclusive, and this has prompted the search for alternative diagnostic techniques. Here, we review recent developments in antibody‐based and nucleic acid‐based diagnostic methods, and their applications in plant pathology. We also highlight some new developments in diagnostics that are likely to make an impact in the future.
Can genetic manipulation of plant nitrogen assimilation enzymes result in increased crop yield and greater N‐use efficiency? An assessment
Authors: ANDREWS M , LEA P J , RAVEN J A , LINDSEY K
Published: July 2006

The literature on the relations between plant nitrogen (N) assimilation enzymes and plant/crop N assimilation, growth and yield is reviewed to assess if genetic manipulation of the activities of N assimilation enzymes can result in increased yield and/or increased N use efficiency. The available data indicate that (I) levels of N assimilation enzymes do not limit primary N assimilation and hence yield; (II) root or shoot nitrate assimilation can have advantages under specific environmental conditions; (III) for cereals, cytosolic glutamine synthetase (GS1) is a key enzyme in the mobilisation of N from senescing leaves and its activity in senescing leaves is positively related to yield; and (TV) for rice (Oryza sativd), NADH‐glutamate synthase (NADH‐GOGAT) is important in the utilisation of N in grain filling and its activity in developing grains is positively related to yield. In our opinion, selection of plants, from either a genetically manipulated population or genetic resources, with expression of nitrate reductase/nitrite reductase primarily in the root or shoot should increase plant/crop growth and hence yield under specific environmental conditions. In addition for cereals the selection of plants with high GS1 in senescing leaves and in some cases high NADH‐GOGAT in developing grains could help maximise the retrieval of plant N in seeds.
Control of smoulder (Botrytis narcissicold) in narcissus with fungicides
Authors: O'NEILL T M , HANKS G R , WILSON D W
Published: July 2006

Smoulder, caused by Botrytis narcissicola, is the most widespread foliar disease of narcissus (Narcissus cultivars) in the UK and causes significant losses in bulb and flower yield. A range of current and novel fungicide treatments was examined to determine if control of the disease could be improved and to measure the effect of treatments on bulb yield. In assays on pot‐grown plants, carbendazim+flusilazole, epoxiconazole, iprodione + thiophanate‐methyl, tebuconazole and vinclozolin reduced lesion size by more than 90%, compared with untreated plants, when applied 1 day before inoculation with the fungus; vinclozolin and tebuconazole were also effective when applied 2 days after inoculation. In field experiments in Cambridgeshire and Lincolnshire, significant reductions were observed in secondary smoulder symptoms (leaf lesions and stem rot) following fungicide sprays. Spray programmes of the novel fungicides azoxystrobin, cyprodinil, kresoxim‐methyl, tebuconazole and pyrimethanil were as effective, or more so, than the standard treatments (chlorothalonil, vinclozolin) used by growers. Mixtures of carbendazim + tebuconazole and azoxystrobin + tebuconazole also gave effective control of smoulder. Programmes of four to six sprays, using two or three fungicides with different modes of action, applied alternately, reduced smoulder by 35–69% and increased bulb yields by 7–59%. Although treatment around and after flowering resulted in the greatest control of secondary smoulder, treatment before flowering was required for the highest bulb yields. The choice of fungicides for use in spray programmes to provide effective and reliable control of smoulder, and the possibility of control using fewer sprays, are discussed.
Autumn, winter and spring dynamics of aphid Sitobion avenae and parasitoid Aphidius rhopalosiphi interactions
Authors: LEGRAND M A , COLINET H , VERNON P , HANCE T
Published: July 2006

The potential of parasitoids for aphid control during summer has been well documented. Few results are available on the impact of parasitoid populations on aphid hosts during autumn and winter and on the dynamics of their interactions during this period. The population development of Sitobion avenae, in Belgium, is analysed, from October to April, in the presence and absence of the parasitoid Aphidius rhopalosiphi. In the presence of parasitoids in winter, aphid populations decreased markedly and remained low at the beginning of spring. Induction of winter diapause in A. rhopalosiphi was observed during November at a mean temperature of 6.3°C and a decreasing photoperiod from 9.5–8.5 h of day light. A large range of A. rhopalosiphi mummy colourations, between dark and light, was noticed. This range of colouration did not allow a clear‐cut distinction between diapausing and non‐diapausing individuals of A. rhopalosiphi. The influence of seasonal weather and particularly temperature conditions on parasitoid mortality, strategy for overwintering and aphid population dynamics are discussed.
Spatial sampling to detect slug abundance in an arable field
Authors: ARCHARD GABRIELLE A , BOHAN DAVID A , HUGHES LOUISE , WILTSHIRE CHRISTOPHER W
Published: July 2006

Overuse of molluscicides by farmers in arable systems can lead to environmental and product contamination. Here we assess a simple and inexpensive surface trapping method for monitoring populations of slugs(Deroceras reticulatum and Arion intermedius). This method was biased against small slugs, and againstA. intermedius, when compared to direct soil sampling. Regression was used to model the relationship between the results of surface trapping and soil sampling methods. Spatial Analysis by Distance IndicEs (SADIE) algorithms were used to describe the spatial relationships between the two sets of samples. Using both traditional statistical methods and spatial statistics, the spatial information collected from surface traps was sufficient to identify patches and gaps in slug numbers and possibly to allow the spot application of slug control, and thus provide land managers who experience slug damage with a way of reducing molluscicides use, whilst maintaining slug control. Further improvements and applications of the model are discussed.
Effects of long‐term salt stress on antioxidant defence systems, leaf water relations and chloroplast ultrastructure of potato plants
Authors: FIDALGO FERNANDA , SANTOS ARLETE , SANTOS ISABEL , SALEMA R
Published: July 2006

The effect of long‐term (30 days) NaCl treatments (100 mM and 200 mM) on the activity of some antioxidant enzymes, level of antioxidant metabolites, water relations and chloroplast ultrastructure, was studied in potato (Solanum tuberosum cv. Désirée) leaves. Salt stress negatively affected relative water content, leaf stomatal conductance and transpiration rate. In treated plants, proline was enhanced, but there was a significant decrease in ascorbate and proteins. Total superoxide dismutase activity was increased. The isozyme patterns detected in native gels from salt‐irrigated plants were not changed although all the isoforms appeared more heavily stained due to higher activity. In contrast, at both levels of NaCl, catalase activity decreased and ascorbate peroxidase activity showed no significant change in comparison with an untreated control. At ultrastructural level, only thylakoid swelling and a decrease in the amount of grana stacking was observed in treated plants. The overall behaviour of the antioxidant enzymes suggests an increase of cellular H2O2 that would contribute to the oxidative stress of potato plants, but which may be alleviated somewhat by the enhanced levels of proline.
First impact of biotechnology in the EU: Bt maize adoption in Spain
Authors: DEMONT M , TOLLENS E
Published: July 2006

In the present paper a bio‐economic model was constructed to estimate the impact of a biotechnology innovation in EU agriculture. Transgenic Bt maize offers the potential to efficiently control corn borers that cause economically important losses in maize growing in Spain. Since 1998, Syngenta has commercialised the variety Compa CB, equivalent to an annual maize area of about 25 000 ha. During the 6‐year period 1998–2003, a total welfare gain of 15.5 million euros was estimated from the adoption of Bt maize, of which Spanish farmers captured two thirds, the rest accruing to the seed industry.
Loss of decreased‐rubisco phenotype between generations of wheat transformed with antisense and sense rbcS
Authors: MITCHELL ROWAN A C , JOYCE PRIYA A , RONG HONGLIN , EVANS VICTORIA J , MADGWICK PIPPA J , PARRY MARTIN A J
Published: July 2006

The elite UK winter wheat cv. Riband was transformed with constructs containing rbcS in sense and antisense orientations driven by the maize ubiquitin promoter with a transformation efficiency of 1.2%. Of 77 primary transformants 31% of the sense‐rbcS transformed lines and 78% of the antisense‐rbcS transformed lines had decreased rubisco content compared to wild‐type and marker‐only controls, with decreases of up to 60%. However, in the T1 progeny which inherited the transgene, only 5% showed significantly decreased rubisco content and these effects were on the margins of significance. Five potential T2 homozygous lines from T1 parents which had transgene segregation consistent with a single locus were identified. There was no significant decrease in rubisco content relative to wild‐type in any of these lines (LSD of 8% for P= 0.05). Expression of antisense rbcS transgenes in two of these T2 lines was low but was increased following exposure of the plants to 37°C for 48 h. However this did not induce a significant decrease in rubisco protein content relative to controls. Southern analysis of two antisense lines showed that they had low copy number and 1–2 insertion events. In one of the two lines there was increased methylation of the ubiquitin intron in T2 samples compared to the TO primary transformant. Further work is required to establish whether methylation occurred in all the lines which lost the phenotype, and therefore the likelihood of this being the cause. The disappearance of the decreased rubisco‐content phenotype between generations may therefore be attributable to (1) greater activity of the ubiquitin promoter due to greater stress in the T0 generation plants and/or (2) increased methylation of the transgene promoter region between generations.
Proteome‐level changes in the roots of Pisum sativum in response to salinity
Authors: KAV NAT N V , SRIVASTAVA SANJEEVA , GOONEWARDENE LAKSIRI , BLADE STANFORD F
Published: July 2006

We initiated a proteomics‐based approach to identify root proteins affected by salinity in pea (Pisum sativum cv. Cutlass). Salinity stress was imposed either on 2‐wk old pea plants by watering with salt water over 6 wk or by germinating and growing pea seeds for 7 days in Petri dishes. Concentrations of NaCl above 75 mM had significant negative effects on growth and development of peas in both systems. Salinity‐induced root proteome‐level changes in pea were investigated by 2‐D electrophoresis of proteins from control, 75 and 150 mM NaCl‐treated plants and seedlings. The majority of the protein spots visualised showed reproducible abundance in root protein extracts from whole plants and seedlings. Of these proteins, 35 spots that exhibited significant changes in abundance due to NaCl treatment were selected for identification using ESI‐Q‐TOF MS/MS. The identities of these proteins, which include pathogenesis‐related (PR) 10 proteins, antioxidant enzymes such as superoxide dismutase (SOD) as well as nucleoside diphosphate kinase (NDPK) are presented, and the roles of some of them in mediating responses of pea to salinity are discussed. This is the first report of salinity‐induced changes in the root proteome of pea that suggests a potential role for PR10 proteins in salinity stress responses. Our findings also suggest the possible existence of a novel signal transduction pathway involving SOD, H2O2, NDPK and PR10 proteins with a potentially crucial role in abiotic stress responses.
An overview of the factors affecting sugar content of potatoes
Authors: KUMAR DINESH , SINGH B P , KUMAR PARVEEN
Published: July 2006

Potatoes destined for making chips, French fries and other fried products, need to have low sugar content to avoid browning of the finished product. The sugar content of potatoes is determined by the genotype and several pre‐ and post‐harvest factors. The major pre‐harvest factors affecting sugar content are crop maturity, temperature during growth, mineral nutrition and irrigation, while important post‐harvest factors are mechanical stresses and storage conditions. Each genotype requires an ideal pre‐and post‐harvest treatment to maintain low sugar levels; any kind of stress results in sugar accumulations.
The effects of temperature and light integral on early vegetative growth and chlorophyll fluorescence of four contrasting genotypes of cacao (Theobroma cacao)
Authors: DAYMOND A J , HADLEY P
Published: July 2006

The effect of temperature on early vegetative growth, leaf chlorophyll fluorescence and chlorophyll content was examined on four genotypes of cacao (Amelonado, AMAZ 15–15, SCA 6 and SPEC 54/1). A controlled environment glasshouse was used to simulate the temperature conditions of three cacao‐growing regions (Bahia, Brazil; Tafo, Ghana and Lower Perak, Malaysia) over the course of a year. Base temperatures calculated from increments in main stem growth varied from 18.6°C for AMAZ 15/15 to 20.8°C for SPEC 54/1. Temporal variation in Fv/Fm observed for two of the clones (SCA 6 and SPEC 54/1) in two of the compartments were correlated with temperature differences over time. Significant differences were also recorded between genotypes in leaf chlorophyll content. It was shown that variation over time in leaf chlorophyll content could be quantified accurately as a function of temperature and light integral. The results imply that genetic variability exists in cacao in response to temperature stress.
Tebufenozide distorted codling moth larval growth and reproduction, and controlled field populations
Authors: SMAGGHE G , BYLEMANS D , MEDINA P , BUDIA F , AVILLA J , VIÑUELA E
Published: July 2006

The activity of the ecdysteroid agonist tebufenozide was evaluated on the codling moth, Cydia pomonella. Tebufenozide affected larval feeding and growth, showing clear symptoms of a double head capsule. Under the SEM and TEM, symptoms of precocious apolysis of the larval integument were observed. Although this process was accompanied with a great inhibition of locomotion, muscle attachment to the new cuticle seemed not to be affected confirming the primary mode of action of tebufenozide as ecdysteroid‐like. In addition, tebufenozide exerted a sterilising action in female and male adults in the laboratory. Finally, the potency of tebufenozide was evaluated in an experimental orchard for commercial apple production in Belgium being, at least, as effective as diflubenzuron.
The effect of cassava mosaic geminiviruses on symptom severity, growth and root yield of a cassava mosaic virus disease‐susceptible cultivar in Uganda
Authors: OWOR B , LEGG J P , OKAO‐OKUJA G , OBONYO R , OGENGA‐LATIGO M W
Published: July 2006

A study was carried out to assess the effect of different cassava mosaic geminiviruses (CMGs) occurring in Uganda on the growth and yield of the susceptible local cultivar ‘Ebwanateraka’. Plants infected with African cassava mosaic virus (ACMV), ‘mild’ and ‘severe’ strains of East African cassava mosaic virus‐Uganda (EACMV‐UG2) and both ACMV and EACMV‐UG2 were grown in two experiments in Kabula, Lyantonde in western Uganda. The most severe disease developed in plants co‐infected with ACMV and EACMV‐UG2 and in those infected with the ‘severe’ form of EACMV‐UG2 alone; disease was least severe in plants infected with the ‘mild’ strain of EACMV‐UG2. ACMV‐infected plants and those infected with the ‘mild’ strain of EACMV‐UG2 were tallest in the 1999–2000 and 2000–2001 trials, respectively; plants dually infected with ACMV and EACMV‐UG2 were shortest in both trials. Plants infected with ‘mild’ EACMV‐UG2 yielded the largest number and the heaviest tuberous roots followed by ACMV and EACMV‐UG2 ‘severe’, respectively, whilst plants dually infected with ACMV and EACMV‐UG2 yielded the least considering the two trials together. Reduction in tuberous root weight was greatest in plants dually infected with ACMV and EACMV‐UG2, averaging 82%. Losses attributed to ACMV alone, EACMV‐UG2 ‘mild’ and EACMV‐UG2 ‘severe’ were 42%, 12% and 68%, respectively. Fifty percent and 48% of the plants infected with both ACMV and EACMV‐UG2 gave no root yield in 1999–2000 and 2000–2001, respectively. These results indicate that CMGs, whether in single or mixed infections, reduce root yield and numbers of tuberous roots produced and that losses are substantially increased following mixed infection.
A yen for sushi: an analysis of demographic and behavioural patterns of sushi consumption in Japan
Authors: De Silva Devarahandhi , Yamao Masahiro
Published: July 2006

Sushi is an ancient Japanese art popularized as the crown prince of Pacific Rim party food. The main objective of this study was to analyse Japanese consumers’ sushi purchasing behaviour and their attitudes towards consumption of sushi. This paper also reports the timeline for sushi businesses in Japan. Data on consumers’ sushi consumption habits, demographic characteristics and attitudes towards sushi were collected using structured questionnaires and informal interviews. The sample of consumers included 108 individuals from the Hiroshima Prefecture, Japan. Sushi is the most popular traditional food among Japanese consumers. The most common frequency for having sushi meals was between once and less than once a month. Older women were the heaviest consumers, preferring to purchase from supermarkets rather than from specialized sushi bars. Sushi made from tuna was in the highest demand (76%), with salmon as a second choice. The ‘freshness of fish’ and the ‘special price of sushi’ were the most important factors for the final purchasing decision. Sushi consumption patterns in Japan seem to closely reflect the evolution of households’ life cycle.
Food acceptance and acculturation
Authors: Mitchell Janet
Published: July 2006

Despite the notion held by many British people that ‘sausages and your joint of beef or your traditional meat and two vegetables or stews, pies that sort of thing’ represents typical British food, it appears that new dishes are replacing the old. A list of the nation’s 10 favourite dishes based on a survey conducted in 2003 by the British Broadcasting Corporation revealed spaghetti Bolognese, and curry and rice as the nation’s two favourite dishes. This paper questions how these dishes have become mainstream British dishes. The study relates immigration to changes in British food choices by examining popular 20th century cookbooks and relating the incorporation of new dishes to changes in the ethnicity of the British population brought about by immigration. The results reveal the importance of meal structure in acceptance and popularization of immigrant foods by the host population. It reveals acculturation as a two‐way process that has contributed to the evolution of British food habits.
Roselle/sorrel (Hibiscus subdariffa L.) wines with varying calyx puree and total soluble solids: sensory acceptance, quantitative descriptive and physicochemical analysis
Authors: Mounigan Pascale , Badrie Neela
Published: July 2006

Effects of varying roselle sorrel (Hibiscus sabdariffa L) puree and total soluble solids (TSS) on physicochemical properties and sensory acceptance of wines were investigated. For puree, calyces were hot‐water processed at 90°C for 30 min, cooled and treated with 1.0% pectolase at 23°C for 24 h. Wine treatments were w/v 20% puree/20°Brix, 30% puree/26°Brix and 30% puree/30°Brix. Wines varied in chroma (P < 0.05), pH (P < 0.01), total titratable acidity (P < 0.01), TSS (P < 0.01), transmission (P < 0.01) and sensory colour (P < 0.01), clarity (P < 0.01), flavour (P < 0.05), balance (P < 0.05) and overall acceptability (P < 0.05). Wines with higher puree had more acceptable (P < 0.05) flavour. Sorrel wine of 30% sorrel puree/26°Brix was most acceptable overall (P < 0.05) of wines, with descriptors of bright clarity, intense redness, high alcohol, strong balance and weak bitterness. The reading of health benefits on sorrel influenced (P < 0.05) only hedonic colour of wines. There was no (P > 0.05) correlation between hedonic scores and descriptive intensity scores.
PRESERVATION OF FISH SPREAD WITH ENTEROCINS 1071A AND 1071B, TWO ANTIMICROBIAL PEPTIDES PRODUCED BY ENTEROCOCCUS FAECALIS BFE 1071
Authors: DICKS LEON M.T. , TODOROV SVETOSLAV D. , VAN DER MERWE MARLA P. , DALTON ANNELINE , HOFFMAN LOUW C.
Published: July 2006

Enterocins 1071A and 1071B, produced by Enterococcus faecalis BFE 1071, kept the total aerobic cell numbers in fish spread between 8 × 104 and 2 × 105 cfu/g for the first 6 days of storage. The total aerobic cell numbers in a batch preserved with a combination of sodium benzoate (0.045%, w/w) and potassium sorbate (0.059%, w/w) remained between 8 × 104 and 2 × 105 cfu/g during the first 18 days of storage. In a batch containing no preservatives, cell numbers gradually increased from 1 × 105 to 1 × 108 cfu/g over 21 days. The spoilage organisms were identified as Staphylococcus epidermidis and atypical Proteus vulgaris. The pH of all batches remained constant over the 21‐day storage period, with minimal variations recorded in textural and organoleptic qualities. The number of microbial cells recorded in fish spread preserved with enterocins 1071A and 1071B was 8 × 106 after 21 days of cold storage (4C), whereas microbial cell numbers of 1 × 108 were recorded in fish spread that had not been preserved.
STUDY ON BACTERIAL LOAD DURING GELATIN MANUFACTURING PROCESS AND ITS EFFECT ON FOOD GRADE GELATIN
Authors: SHARMA A. , DOUR P. , SEHGAL R.K.
Published: July 2006

A total of 138 samples from different stages of gelatin manufacturing process were analyzed to detect bacterial contamination of food grade gelatin and to see its effect on the quality of gelatin. The isolated bacterial species included Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Clostridium perfringens, which exhibited gelatinase activity and caused depletion in the nutritional quality of food grade gelatin. Marked changes in the amino acid content with incubation days indicated degradation of food grade gelatin because of the secretion of gelatinases that were depicted by paper chromatography. Because these isolated species are known pathogens and have gelatinolytic properties, their occurrence in food grade gelatin can make it an unsafe and unsuitable for food applications.
PREVALENCE OF THERMOPHILIC CAMPYLOBACTER SPP. IN RETAIL CHICKEN MEAT IN ANKARA
Authors: SAVA ÇI MUSTAFA , ÖZDEMİR HAYDAR
Published: July 2006

From May to August 2004, 127 samples of chicken meat for sale on the retail market in Ankara were analyzed for the prevalence of thermophilic Campylobacter spp. Campylobacter spp. were isolated from 83.4% of the samples analyzed. Campylobacter jejuni was found in 74.8% of all samples. A total of 364 thermophilic Campylobacter strains were isolated and the species distribution among these strains was 70.1% C. jejuni, 21.1% Campylobacter coli and 8.6% Campylobacter lari. The results obtained from the study indicate that hygienic and technical compliance is needed in all stages of poultry processing to reduce contamination and to prevent public health hazard. An integrated HACCP plan must be applied from the farm to the table for the prevention of C. jejuni infections.
VOCAL INDIVIDUALITY OF IN‐AIR WEDDELL SEAL (LEPTONYCHOTES WEDDELLII) PUP “PRIMARY” CALLS
Authors: Collins Kym T. , Terhune John M. , Rogers Tracey L. , Wheatley Kathryn E. , Harcourt Robert G.
Published: July 2006

Abstract

As a result of selective pressures faced during lactation, vocal recognition may play a crucial role in maintaining the phocid mother–pup bond during the period of dependence. To investigate this possibility, we examined whether Weddell seal (Leptonychotes weddellii) pups produce individually distinctive “primary” calls. One temporal, nine fundamental frequency features, and two spectral characteristics were measured. A discriminant function analysis (DFA) of 15 Vestfold Hills pups correctly classified 52% of calls, while the cross‐validation procedure classified 29% of calls to the correct pup. A second DFA of 10 known‐age McMurdo Sound pups correctly classified 44% of “test” calls. For novel calls, the probabilities of attaining such classification rates by chance are low. The relationship between age and call stereotypy indicated that pups 2 wk and older may be more vocally distinctive. Overall, findings suggest that Weddell seal pup “primary” calls are moderately distinctive and only exhibit sufficient stereotypy to aid maternal recognition by approximately two weeks of age.
INTERMINGLING OF DALLI‐TYPE DALL'S PORPOISES INTO A WINTERING TRUEI‐TYPE POPULATION OFF JAPAN: IMPLICATIONS FROM COLOR PATTERNS
Authors: Amano Masao , Hayano Azusa
Published: July 2006

Abstract

There are two major color morphs, truei and dalli types, of the Dall's porpoise and the latter includes two minor morphs. A small number of dalli types are found among truei types off the Pacific coast of Japan, where truei types normally winter. Based on differences in the patch size of dalli‐type porpoises taken by the harpoon fishery, we determined that those dalli types contain both minor morphs. Although the total number of both types in the sample was similar, the proportion of the two types varied seasonally. Sex ratio, body length, and maturity rate were different among the dalli and truei types. These facts strongly suggest that these dalli types were not members of the truei‐type population and were actually migrants from adjacent dalli‐type populations. The definition of the subspecies Phocoenoides dalli dalli and P. d. truei as polymorphic groups is not supported, although we consider that each of the three color morphs is worthy of full subspecific status.
Allochtonous input and trophic level heterogeneity: impact on an aquatic food web
Authors: Lövgren J. , Reinikainen M. , Persson L.
Published: July 2006

The impact of food web complexity in open and closed food webs was explored experimentally under controlled laboratory conditions. We used an aquatic model community consisting of two forms of primary producers, phytoplankton (Scenedesmus obtusiuscusculus) and periphyton (Nitzschia perminuta) and two types of consumers, Daphnia pulex feeding on phytoplankton and Chydorous sphaericus feeding on both periphyton and phytoplankton. Three different food webs all having the phytoplankton and periphyton, but having either one of the consumers or both were set up. These food webs were studied in an open and closed treatment. In the open treatment, phytoplankton was continuously flowing through the aquaria whereas in the closed system all the phytoplankton was delivered at the start of the experiment.

D. pulex had a positive effect on the density of C. sphaericus in both the open and closed treatments. In the open treatment C. sphaericus increased to very high numbers and was able to depress phytoplankton and thereby negatively affect D. pulex. Our study shows that the explicit handling of the population dynamics of both grazers allowed us to show how a compensatory increase in one primary producer due to increased grazing on another primary producer creates a negative feedback between consumers: C. sphaericus increased and negatively affected D. pulex.
A stochastic model for integrating changes in species richness and community similarity across spatial scales
Authors: Cassey Phillip , Blackburn Tim M. , Lockwood Julie L. , Sax Dov F.
Published: July 2006

Human activities have elevated the extinction of natural populations as well as the invasion of new areas by non‐native species. These dual processes of invasion and extinction may change the richness and similarity of communities, but the form these changes take is likely to depend on the manner in which invasions and extinctions occur and the spatial scale at which the changes are measured. Here, we explore the influence of differing patterns of extinction and invasion on the similarity and richness of a meta‐community. In particular, we model simple stochastic processes analogous to realistic modes of human‐mediated introduction of non‐native species and range expansion by native species. We show that different modes of invasion and extinction can produce very different changes in diversity, and that the relative magnitude of these changes depends both on where in the meta‐community diversity is measured and the degree of initial species aggregation. At any spatial scale of measurement, changes in the richness and similarity of communities following invasion and extinction are not necessarily strongly coupled: relatively large increases in richness may or may not also be associated with relatively large increases in similarity among communities. Thus, in real systems, the influence of human‐induced invasions and extinctions on diversity will depend on both the precise mode of these processes (especially invasion), and how species populations are distributed across space.
Multi-Element Unstructured Analyses of Complex Valve Systems
Authors: Ahuja Vineet , Hosangadi Ashvin , Shipman Jeremy , Daines Russell , Woods Jody
Published: July 2006

The safe and reliable operation of high-pressure test stands for rocket engine and component testing places an increased emphasis on the performance of control valves and flow metering devices. In this paper, we will present a series of high-fidelity computational analyses of systems ranging from cryogenic control valves and pressure regulator systems to cavitating venturis that are used to support rocket engine and component testing at NASA Stennis Space Center. A generalized multi-element framework with submodels for grid adaption, grid movement, and multi-phase flow dynamics has been used to carry out the simulations. Such a framework provides the flexibility of resolving the structural and functional complexities that are typically associated with valve-based high-pressure feed systems and have been difficult to deal with using traditional computational fluid dynamics methods. Our simulations revealed a rich variety of flow phenomena such as secondary flow patterns, hydrodynamic instabilities, fluctuating vapor pockets, etc. In the paper, we will discuss performance losses related to cryogenic control valves and provide insight into the physics of the dominant multi-phase fluid transport phenomena that are responsible for the “choking-like” behavior in cryogenic control elements. Additionally, we will provide detailed analyses of the modal instability that is observed in the operation of a pressure regulator valve. Such instabilities are usually not localized and manifest themselves as a system-wide phenomena leading to an undesirable chatter at high flow conditions.
Development of a Tip-Leakage Flow—Part 1: The Flow Over a Range of Reynolds Numbers
Authors: Oweis Ghanem F. , Fry David , Chesnakas Chris J. , Jessup Stuart D. , Ceccio Steven L.
Published: July 2006

An extensive experimental investigation was carried out to examine the tip-leakage flow on ducted propulsors. The flow field around three-bladed, ducted rotors operating in uniform inflow was measured in detail with three-dimensional laser Doppler velocimetry and planar particle imaging velocimetry. Two geometrically similar, ducted rotors were tested over a Reynolds number range from 0.7×106 to 9.2×106 in order to determine how the tip-leakage flow varied with Reynolds number. An identification procedure was used to discern and quantify regions of concentrated vorticity in instantaneous flow fields. Multiple vortices were identified in the wake of the blade tip, with the largest vortex being associated with the tip-leakage flow, and the secondary vortices being associated with the trailing edge vortex and other blade-wake vortices. The evolution of identified vortex quantities with downstream distance is examined. It was found that the strength and core size of the vortices are weakly dependent on Reynolds number, but there are indications that they are affected by variations in the inflowing wall boundary layer on the duct. The core size of the tip-leakage vortex does not vary strongly with varying boundary layer thickness on the blades. Instead, its dimension is on the order of the tip clearance. There is significant flow variability for all Reynolds numbers and rotor configurations. Scaled velocity fluctuations near the axis of the primary vortex increase significantly with downstream distance, suggesting the presence of spatially uncorrelated fine scale secondary vortices and the possible existence of three-dimensional vortex-vortex interactions.
Development of a Tip-Leakage Flow Part 2: Comparison Between the Ducted and Un-ducted Rotor
Authors: Oweis Ghanem F. , Fry David , Chesnakas Chris J. , Jessup Stuart D. , Ceccio Steven L.
Published: July 2006

The vortical flow in the tip region of a three-bladed rotor was examined using particle imaging velocimetry (PIV). The vortex forming at the tip of the un-ducted propeller was compared to the tip-leakage vortex of the ducted rotor. The planar flow fields were used to identify regions of concentrated vorticity and determine instantaneous vortex properties, revealing the presence of a primary tip-leakage vortex surrounded by a number of secondary vortices. Comparison between the ducted and un-ducted rotor indicated that the presence of the duct reduced the relative strength of the primary tip vortex, making its strength a smaller fraction of the overall shed circulation near the tip. The weaker tip-leakage vortex then became closer in strength to the other secondary vortices in the tip-flow region. However, for the rotor tip geometry considered here, the radius of the primary vortex core did not vary substantially between the ducted and un-ducted cases. The variability of the flow was larger for the ducted case, in terms of the primary vortex position, its identified circulation, core size, and inferred core pressure. This variability was also observed in the scaled velocity fluctuations near the core of the vortex.
Robust Volume-Based Approach for the Turbulent Mixing Efficiency
Authors: Aguirre Roberto C. , Catrakis Haris J. , Nathman Jennifer C. , Garcia Philip J.
Published: July 2006

This paper considers the mixture fraction which is often used to quantify the turbulent mixing efficiency in fluid engineering devices. We contrast a volume-based approach, where the mixture fraction is quantified directly using the volume bounded by the interface between mixed versus pure fluid, to a surface-based approach that requires area integrals of all mixed-fluid interfaces. Experimentally, we investigate the resolution-scale robustness of the volume-based approach compared to the small-scale sensitivity of the surface-based approach. The difference in robustness between these approaches has implications for examining, modeling, and optimizing the turbulent mixing efficiency.
Galerkin Least-Squares Finite Element Approximations for Isochoric Flows of Viscoplastic Liquids
Authors: Zinani Flávia , Frey Sérgio
Published: July 2006

The flow of viscoplastic liquids is studied via a finite element stabilized method. Fluids, such as some food products, blood, mud, and polymer solutions, exhibit viscoplastic behavior. In order to approximate this class of liquids, a mechanical model, based on the principles of power expended and mass conservation, is exploited with the Papanastasiou approximation for Casson equation employed to model viscoplasticity. The approximation for the nonlinear set of partial differential equations is performed, using a stabilized finite element methodology. A Galerkin least-squares strategy is employed to avoid the well-known difficulties of the classical Galerkin method in isochoric flows. It circumvents the Babuška-Brezzi condition and handles the asymmetry of the advective operator in high advective flows. Some two-dimensional (2D) viscoplastic flows through a 4:1 planar expansion, for a range of Casson (0⩽Ca⩽10) and Reynolds (0⩽Re⩽50) numbers, have been investigated, paying special attention to the characterization of vortex length and unyielded regions. The numerical results show the arising of regions of unyielded material throughout the flow, strongly affecting the vortex structure, which is reduced with the increase of the Casson number even in flows with considerable inertia.
Effect of Surfactant Additives on Centrifugal Pump Performance
Authors: Ogata Satoshi , Kimura Asano , Watanabe Keizo
Published: July 2006

Performance of a centrifugal pump when handling surfactant solutions was measured experimentally. It was clarified that the pump efficiency with surfactant solutions was higher than that with tap water and increased with an increase in surfactant concentration. The value of maximum flow rate also increased. The total pump head increased with an increase in concentration, and the shaft power decreased with a decrease in the impeller rotating speed. There was an optimal temperature, which maximizes the efficiency. By combining the data for the piping section and for the pump efficiency, it is possible to accurately predict the energy savings of the pumping power in the pipeline system.
The Depth of Correlation in Micro-PIV for High Numerical Aperture and Immersion Objectives
Authors: Bourdon Christopher J. , Olsen Michael G. , Gorby Allen D.
Published: July 2006

The analytical model for the depth of correlation (measurement depth) of a microscopic particle image velocimetry (micro-PIV) experiment derived by Olsen and Adrian (Exp. Fluids, 29, pp. S166–S174, 2000) has been modified to be applicable to experiments using high numerical aperture optics. A series of measurements are presented that experimentally quantify the depth of correlation of micro-PIV velocity measurements which employ high numerical aperture and magnification optics. These measurements demonstrate that the modified analytical model is quite accurate in estimating the depth of correlation in micro-PIV measurements using this class of optics. Additionally, it was found that the Gaussian particle approximation made in this model does not significantly affect the model’s performance. It is also demonstrated that this modified analytical model easily predicts the depth of correlation when viewing into a medium of a different index of refraction than the immersion medium.