311 resultados para isolating
Resumo:
A systematic technique for identifying the environments of construction projects is described. It provides a method for isolating the major variables surrounding construction projects, and is briefly applied to the industries of Britain and Jamaica to illustrate its application. From this, it is inferred that the environment of a Jamaican construction project in systems terms is broadly similar to the environment of a construction project in Britain.
Resumo:
The present invention provides Inter alia, a method for the production of cotton somatic embryos comprising (a) isolating a totipotent stomatal cell-containing epidermal explant from leaf material excised from a cotton plant; and (b) culturing said explant in a basal medium which comprises an embryogenic callus-inducing quantity of an auxin and a cytokinin under an embryogenic callus inducing intensity of light until embryogenic callus is formed; and (c) sub-culturing said embryogenic callus onto a somatic embryo differentiation media to produce said somatic embryos. Plants may be regenerated from the somatic embryos and in a particular embodiment of the invention said totipotent stomatal cell is transformed, prior to the inducement of embryogenic callus, with a polynucleotide that provides for a desired agronomic trait.
Resumo:
The present invention relates to haploid oil palm plants and homozygous doubled haploid oil palm plants. The invention also relates to methods for producing and selecting haploid and doubled haploid plants. More particularly, but not exclusively, the method may be used for selecting haploid and doubled haploid oil palm plants. Haploid and doubled haploid plants are selected by a large-scale screening based on a combination of the phenotype with the use of molecular methods combined with flow cytometry techniques to identify haploid and doubled haploid plants. More particularly, a method for selecting haploid and doubled haploid plants is described comprising: (a) germinating seeds; (b) selecting seedlings with atypical phenotype; (c) assessing heterozygosity using markers; (d) isolating cells from the seedlings and determining the DNA content of the cells; and (e) isolating and purifying the DNA and using defined molecular markers to characterise the genotype of the plant. The haploid oil palm plants may be used for producing homozygous doubled haploid oil palms: doubled haploids may be intercrossed to produce uniform F.sub.1 hybrids of superior properties.
Resumo:
Knowledge is recognised as an important source of competitive advantage and hence there has been increasing academic and practitioner interest in understanding and isolating the factors that contribute to effective knowledge transfer between supply chain actors. The literature identifies power as a salient contributor to the effective operation of a supply chain partnership. However, there is a paucity of empirical research examining how power among actors influences knowledge acquisition and in turn the performance of supply chain partners. The aim of this research is to address this gap by examining the relationship between power, knowledge acquisition and supply chain performance among the supply chain partners of a focal Chinese steel manufacturer. A structured survey was used to collect the necessary data. Two conceptually independent variables – ‘availability of alternatives’ and ‘restraint in the use of power’ – were used to assess actual and realised power, respectively. Controlling for contingencies, we found that the flow of knowledge increased when supply chain actors had limited alternatives and when the more powerful actor exercised restraint in the use of power. Moreover, we found a positive relationship between knowledge acquisition and supply chain performance. This paper enriches the literature by empirically extending our understanding of how power affects knowledge acquisition and performance.
Resumo:
Aims: The aim of this study was to determine if three classes of farm disinfectants were able to select for ciprofloxacin or cyclohexane tolerant [ indicative of a multiple antibiotic resistance ( MAR) phenotype] Escherichia coli and if cyclohexane-tolerant E. coli could be isolated from farms. Methods and Results: Chicken slurry containing ca 1 : 99 ratio ciprofloxacin resistant : susceptible E. coli ( 10 different resistant strains examined) was treated for 24 h with each of the disinfectants and examined for survival of resistant : susceptible strains. Ciprofloxacin-sensitive ( n = 5) and - resistant ( n = 5) E. coli were grown with sublethal concentrations of the disinfectants and then plated to agar containing ciprofloxacin or overlaid with cyclohexane. Escherichia coli ( n = 389) isolated from farms were tested for cyclohexane tolerance. Minimum inhibitory concentrations ( MIC) were determined against representative isolates and mutants. The disinfectants did not select for the ciprofloxacin-resistant E. coli in poultry slurry but following growth with each of the three disinfectants, higher numbers ( Pless than or equal to 0(.)023) of cyclohexane-tolerant E. coli were isolated and these had a MAR phenotype. Of the 389 farm E. coli tested, only one was cyclohexane tolerant. Conclusions: It is possible that in a farm environment, E. coli could be exposed to similar concentrations of the disinfectants that are selected for MAR type organisms under these laboratory conditions. Significance and Impact of the Study: Data from this study suggest that cyclohexane-resistant E. coli are not common on farms, but in view of the ease of isolating them in the laboratory with farm disinfectants, further investigations on farms are warranted.
Resumo:
This article summarizes the main research findings from the first of a series of annual surveys conducted for the British Council of Shopping Centres. The study examines the changing pattern of retailing in the United Kingdom and provides an overview of key research from previous studies in both the U.K. and the United States. The main findings are then presented, including an examination of the impact of e-commerce on sales and rental values and on the future space and ownership / leasing requirements of U.K. retailers for 2000-2005. The impact on a shopping center in a case study town in the U.K. is also considered. The difficulties of isolating the impact of e-commerce from other forces for change in retailing are highlighted. In contrast to other viewpoints, the results show that e-commerce will not mean the death of conventional store-based U.K. retailing, although further benchmark research is needed.
Resumo:
In public goods experiments, stochastic choice, censoring and motivational heterogeneity give scope for disagreement over the extent of unselfishness, and whether it is reciprocal or altruistic. We show that these problems can be addressed econometrically, by estimating a finite mixture model to isolate types, incorporating double censoring and a tremble term. Most subjects act selfishly, but a substantial proportion are reciprocal with altruism playing only a marginal role. Isolating reciprocators enables a test of Sugden’s model of voluntary contributions. We estimate that reciprocators display a self-serving bias relative to the model.
Resumo:
Pollinator declines have raised concerns about the persistence of plant species that depend on insect pollination, in particular by bees, for their reproduction. The impact of pollinator declines remains unknown for species-rich plant communities found in temperate seminatural grasslands. We investigated effects of land-use intensity in the surrounding landscape on the distribution of plant traits related to insect pollination in 239 European seminatural grasslands. Increasing arable land use in the surrounding landscape consistently reduced the density of plants depending on bee and insect pollination. Similarly, the relative abundance of bee-pollination-dependent plants increased with higher proportions of non-arable agricultural land (e.g. permanent grassland). This was paralleled by an overall increase in bee abundance and diversity. By isolating the impact of the surrounding landscape from effects of local habitat quality, we show for the first time that grassland plants dependent on insect pollination are particularly susceptible to increasing land-use intensity in the landscape.
Resumo:
Despite the importance of dust aerosol in the Earth system, state-of-the-art models show a large variety for North African dust emission. This study presents a systematic evaluation of dust emitting-winds in 30 years of the historical model simulation with the UK Met Office Earth-system model HadGEM2-ES for the Coupled Model Intercomparison Project Phase 5. Isolating the effect of winds on dust emission and using an automated detection for nocturnal low-level jets (NLLJs) allow an in-depth evaluation of the model performance for dust emission from a meteorological perspective. The findings highlight that NLLJs are a key driver for dust emission in HadGEM2-ES in terms of occurrence frequency and strength. The annually and spatially averaged occurrence frequency of NLLJs is similar in HadGEM2-ES and ERA-Interim from the European Centre for Medium-Range Weather Forecasts. Compared to ERA-Interim, a stronger pressure ridge over northern Africa in winter and the southward displaced heat low in summer result in differences in location and strength of NLLJs. Particularly the larger geostrophic winds associated with the stronger ridge have a strengthening effect on NLLJs over parts of West Africa in winter. Stronger NLLJs in summer may rather result from an artificially increased mixing coefficient under stable stratification that is weaker in HadGEM2-ES. NLLJs in the Bodélé Depression are affected by stronger synoptic-scale pressure gradients in HadGEM2-ES. Wintertime geostrophic winds can even be so strong that the associated vertical wind shear prevents the formation of NLLJs. These results call for further model improvements in the synoptic-scale dynamics and the physical parametrization of the nocturnal stable boundary layer to better represent dust-emitting processes in the atmospheric model. The new approach could be used for identifying systematic behavior in other models with respect to meteorological processes for dust emission. This would help to improve dust emission simulations and contribute to decreasing the currently large uncertainty in climate change projections with respect to dust aerosol.
Resumo:
Structural, vibrational, and energetic properties of new molecular species, HSI and HIS are investigated for the first time using a state-of-the-art theoretical approach. These molecules can be easily differentiated by their geometric parameters and vibrational spectra. HSI is much more stable, and a direct unimolecular isomerization is very unlikely. Kinetics estimates predict that only at low temperatures there is a possibility of isolating HIS. For HS-I, we estimate a bond dissociation energy of 46.25 kcal/mol, and a heat of formation at 298.15 K of 12.84 kcal/mol. For the H(2)S + I(2) -> HSI + HI reaction enthalpy, we found 8.40 kcal/ mol. (C) 2008 Elsevier B.V. All rights reserved.
Resumo:
Allt hårdare lagkrav gör att det är svårt att energieffektivisera befintliga byggnader utan att förändra deras utseende. Syftet med examensarbetet är att utreda hur stor energieffektivisering, för tre befintliga småhus uppförda under 1900-talet, som är möjlig att uppnå genom förbättring av byggnadernas klimatskal, det vill säga tak, väggar, golv, fönster och dörrar, utan att förvanska byggnadernas utseende och samtidigt bevara deras kulturhistoriska värden. Arbetet bestod av en förstudie där tre byggnader identifierades, ett undersökningsskede där information om byggnaderna togs fram och ett slutsatsskede där energibesparande åtgärdsförslag togs fram och utvärderades. Byggnader som var goda representanter för sin tid och stil söktes. Byggnader från 1910-talet, 1930-talet och 1970-talet, lokaliserades. Sedan gjordes det fallstudier med intervjuer och inventeringar. För att utreda byggnadens klimatskal utfördes u-värdesberäkningar och energiberäkningar av befintliga byggander och byggnader baserade på föreslagna åtgärdsförslag. Ingen av byggnaderna nådde efter föreslagna åtgärder ner till passivhuskravet 59 kWh/år/m2 Atemp eller BBR-kravet 110 kWh/år/m2 Atemp för en byggnads specifika energianvändning. Den största möjliga energieffektivisering för de tre byggnaderna uppförda under 1900-talet, som är möjlig att uppnå utan att förvanska byggnadernas utseende och samtidigt bevara deras kulturhistoriska värden är 13,0 kWh/år/m2 Atemp, 49,7 kWh/år/m2 Atemp respektive 64,8 kWh/år/m2 Atemp. Slutsatser från arbetet är att byggnader från 1910-tal kan åtgärdas genom att isolera fönstren, sätta dit en extra dörr på insidan av ytterdörren samt tilläggsisolera snedtaket. Byggnader från 1930-tal kan åtgärdas genom att isolera fönstren med en isolerruta på insidan av fönstret och dörrarna med en extra dörr på insidan av ytterdörren. Byggnader från 1970-tal kan åtgärda fönstren genom att byta ut dem till energifönster, ingen åtgärd för golvet men fasaden isoleras utvändigt med vakuumisolering. Byggnaden från 1970-talet klarade sig bäst i jämförelsen eftersom den var i autentiskt skick från början vilket gjorde att förbättringen blev större än för till exempel byggnaden från 1910-talet som redan var ombyggd innan åtgärder föreslogs.
Resumo:
In 1977, when teacher education inSwedenwas incorporated into the university system, the main reason was to transform it into an academic tradition. Now, nearly 30 years later, there is still tension between the academic and the vocational tradition; they show up as different and separated elements in a program that is meant to prepare students for a career as a teacher and for a possible future career as a researcher in this field. This tension gives rise to a risk of allowing parallel “tracks” to develop and of isolating the degree thesis work from other courses. On the teacher-training program in which we are involved, close co-operation with partner-schools, where the practical part of the program takes place, has been established. Here, the students´ degree theses are an important factor in making this co-operation work on a concrete level. Accordingly, the purpose of the degree thesis is both to reflect problems in schools and contribute to better teaching in the individual school, but also to offer relevant educational subject matter to the students, which may be adapted as an element in the university’s research environments. From these points of view, the degree thesis is an important part of teacher education and rather more than just a single course. The degree thesis should be an element that gives the students an opportunity to show that they have reached central goals in the teacher education program. It should also be an integral part in the development of critical and scholarly thinking, deepening pedagogical and didactic knowledge and giving the students an opportunity to apply research methods. We will here use two minor case studies: one that compares teacher education programs in five Swedish universities and one minor study at one of those universities, in order to elaborate on the questions: - What purpose has a degree thesis and what role does it play in teacher education? - What criteria are relevant to assessing a degree thesis and what qualities do the degree theses have? - Is it possible to assess a degree thesis fairly and what happens to students who do not pass? - How could the degree thesis be used to improve the contact between the teacher education program and its partner schools in order to contribute to the development of the individual school?
Resumo:
The history of a gay and lesbian student community at Colby seems to point to the difficulty of visibility. For students who were able to find others like themselves, their group of lesbian and gay friends had to remain underground. For students who were grappling with their newly found, socially stigmatized sexuality, the experience was isolating if they did not know where to find others like themselves. This paper seeks to address the social forces that kept sexually variant students from expressing their sexual identities openly on campus. Part of this difficulty is attributable to the compulsory heterosexuality assumed by general American society at the time, manifested in the silence or outright hostility directed against homosexuals. Naturally, Colby students replicated this assumption. Some of the students we interviewed seemed to internalize compulsory heterosexuality, while it was forced upon others. Religion and psychology were two methods of enforcing heterosexuality that were relevant to the people we interviewed. Another significant obstacle to visibility was Colby's location and the nature of Colby's student body. Waterville, unlike more urban cities, did not have a history of gay life, and thus an established gay community or gay identity into which one could be socialized. Colby, as a small, homogeneous and isolated space, posed difficulties in establishing a gay community as the population to draw from was small and regulated.
Resumo:
To date there are no analytical techniques designed to exclusively measure bioavailable iron in marine environments. The goal of this research is to develop such a technique by isolating the bioavailable iron using the terrestrial siderophore desferrioxamine B (DFB). This project contained many challenging aspects, but the specific goal of this study was to develop a robust analytical technique for quantification of Fe(III)-DFB complexes at nanomolar concentrations. Past work showed that oxalate (Ox) promotes photodissociation of Fe(III)-DFB to Fe(Il), and we are specifically interested in the mechanism of this process. A model was developed using known thermodynamic constants for Fe(III)-DFB and Fe(III) oxalato complexes and adjusting for ionic strength. The model was confirmed by monitoring the UV-VIS absorbance of the system at a variety of oxalate concentrations and pH. The model did not include ternary complexes. Next., the rate of Fe(1I) production during UV irradiation was examined. The results showed that the rate of Fe(II) production was based entirely on the [Fe(Ox)?]3- speciation, and that reoxidation of Fe(II) occurred via reactive oxygen intermediates. This reoxidation could be avoided by either decreasing the oxygen concentration or by adding a Fe(II) stabilizing reagent, such as ferrozine. Further studies need to be done to confirm that these results apply at sub nanomolar concentrations, and the issue of Fe(II) reoxidation at lower Fe concentrations needs to be addressed.
Resumo:
Volvox carteri, a multi-celled green algae, can grow synchronously given a sixteen hour light period followed by an eight hour dark period, a cycle which is repeated for a 48 hour growth cycle total. Near the end of each light period, reproductive cells divide rapidly resulting in the differentiation of ceIls. When the dark period begins, this differentiation stops and the cells remain dormant with little protein synthesis or differentiation occurring. Immediately after the lights come back on, however, the cells again undergo rapid protein synthesis and complete their differentiation. Previous studies have concluded that Volvox carteri discontinue protein synthesis during the dark phase due to regulation at the translational level and not the transcriptional level. Therefore, the inhibition of protein synthesis does not lie in the transfer of the protein coding sequence from DNA to mRNA, but rather in the transfer of this information from the mRNA to the ribosomes. My research examined this translational regulation to determine the factor(s) causing the discontinuation of protein synthesis during the dark phase. Evidence from other research further suggests that the control of translation lies in the initiation step rather than the elongation step. Eukaryotic initiation factors aid in the binding of the ribosomal subunits to the mRNA to initiate protein synthesis. It is known that initiation factors can be modified by phosphorylation, regulating their activity. Therefore, my study focused upon isolating some of these initiation factors in order to determine whether or not such modifications are responsible for the inhibition of dark phase protein synthesis in Volvox carteri.