bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation and characterization of microsatellite loci in Senecio
Authors: LIU GUOQING , HEGARTY MATTHEW J. , EDWARDS KEITH J. , HISCOCK SIMON J. , ABBOTT RICHARD J.
Published: November 2004

Interspecific hybridization has resulted in the recent origin of several hybrid Senecio taxa at diploid, tetraploid and hexaploid levels. As part of research aimed at constructing and comparing genomic maps of each of these taxa and their parents, we have isolated microsatellite loci from genomic DNA libraries of S. vulgaris and S. squalidus. Primers of 35 loci amplified microsatellites resolved in agarose gels from one or more of S. vulgaris, S. squalidus, S. aethnensis and S. chrysanthemifolius. Approximately 71% of primers amplified a product in all four species. A survey of microsatellite variation in S. chrysanthemifolius over a subset of 14 loci resolved 2–11 alleles per locus in polyacrylamide gels with expected heterozygosity (HE) ranging from 0.26 to 0.87.
A multiplex panel of dinucleotide microsatellite markers for the water vole, Arvicola terrestris
Authors: BERTHIER K. , GALAN M. , WEBER A. , LOISEAU A. , COSSON J. F.
Published: November 2004

We isolated and characterized nine polymorphic dinucleotide microsatellite loci in the fossorial vole Arvicola terrestris Scherman (Shaw). A multiplex panel comprising all nine loci was developed and its application to a set of 31 individuals allowed clear and easy characterization of allele sizes. The number of alleles range from three to 14 per locus with the observed heterozygosity ranging from 0.42 to 0.90. These markers will be useful for analysis of questions concerning population genetic structure and reproductive behaviour.
A simple and inexpensive method for producing fluorescently labelled size standard
Authors: SYMONDS V. VAUGHAN , LLOYD ALAN M.
Published: November 2004

Current methods of automated genotyping offer many advantages over traditional gel‐based approaches, including reduced handling and processing times, and increased accuracy and consistency. Unfortunately, these advances have come at a substantial cost; at present, roughly one‐half of the cost of automated genotyping is due to fluorescently labelled internal size standard. Here we describe detailed methodologies for generating a highly consistent, fluorescently labelled, internal size standard using polymerase chain reaction (PCR). The methods are simple and the required reagents are inexpensive, making the in‐house production of fluorescently labelled size standards a more widely accessible alternative to commercially available size standards.
Polymorphic microsatellite markers for the gliding marsupials Petaurus australis and Petaurus breviceps
Authors: BROWN M. , KENDAL T. A. , COOKSLEY H. , SAINT K. M. , TAYLOR A. C. , CARTHEW S. M. , COOPER S. J. B.
Published: November 2004

Habitat destruction is causing population decline of many hollow dependent species such as gliding marsupials of the Family Petauridae. Three petaurid species are now listed in some Australian states as either threatened, rare or vulnerable, precipitating a need for information on their basic biology and population structure. We isolated and characterized three polymorphic microsatellite loci from the yellow‐bellied glider (Petaurus australis) and six polymorphic microsatellite loci from the sugar glider (P. breviceps). Per‐locus heterozygosities range from 42%–92%, and cross‐species amplification studies show that between five and seven loci are polymorphic in the two target species as well as a related species P. norfolcensis.
Development of simple sequence repeat markers for Botryosphaeria spp. with Fusicoccum anamorphs
Authors: SLIPPERS BERNARD , BURGESS TREENA , WINGFIELD BRENDA D. , CROUS PEDRO W. , COUTINHO TERESA A. , WINGFIELD MICHAEL J.
Published: November 2004

We report the development of eight sets of microsatellite markers for the ascomycete fungus and tree pathogen, Botryosphaeria parva. The primers were identified after cloning and sequencing of fragments amplified using simple sequence repeat (SSR) primers. Genome walking was used to determine unknown sequences on either side of new SSRs. The primers were tested and proved useful in nine other Botryosphaeria species that all have Fusicoccum anamorphs, similar to B. parva.
Isolation and characterization of microsatellite markers in the liver fluke (Fasciola hepatica)
Authors: HURTREZ‐BOUSSÈS S. , DURAND P. , JABBOUR‐ZAHAB R. , GUÉGAN J.‐F. , MEUNIER C. , BARGUES M.‐D. , MAS‐COMA S. , RENAUD F.
Published: November 2004

Six microsatellite markers were isolated from Fasciola hepatica, a re‐emerging parasite that causes important veterinary and public health problems. In a sample of 52 liver flukes from a region of hyperendemicity (Bolivian Altiplano), five microsatellite were polymorphic. Our results showed that liver flukes present important genetic variability, suggesting a preferential outcrossing reproduction mode for this hermaphroditic parasite.
Low genotyping error rates in wild ungulate faeces sampled in winter
Authors: MAUDET C. , LUIKART G. , DUBRAY D. , VON HARDENBERG A. , TABERLET P.
Published: November 2004

We show that Alpine ibex (Capra ibex) and Corsican mouflon (Ovis musimon) faeces yield useful DNA for microsatellite analysis, however, we detected higher genotyping error rates for spring faeces than for winter faeces. We quantified the genotyping error rate by repeatedly genotyping four microsatellites. Respectively, 99 and 95% of mouflon and ibex genotyping repetitions provided a correct genotype using winter samples, whereas spring samples provided only 52 and 59% correct genotypes. Thus, before starting a noninvasive study, we recommend that researchers conduct a pilot study to quantify genotyping error rates for each season, population and species to be studied.
Characterization of microsatellite markers in the threatened sand skink (Neoseps reynoldsi)
Authors: REID D. T. , ASHTON K. G. , ZAMUDIO K. R.
Published: November 2004

We characterized microsatellite loci for the sand skink (Neoseps reynoldsi) for future studies of genetic structure in this threatened taxon. We screened a partial genomic library enriched for microsatellites, designed primers for eight loci and assessed these markers for polymorphism across 11 populations in central Florida. Preliminary analyses indicate deviations from Hardy–Weinberg expectations for most loci, suggesting population genetic structure across the sampled populations; therefore, understanding genetic connectivity is critical for maintaining genetic variation in this species.
Microsatellite markers for two species of dampwood termites in the genus Zootermopsis (Isoptera: Termopsidae)
Authors: ALDRICH BENJAMIN T. , KAMBHAMPATI SRINIVAS
Published: November 2004

Dampwood termites in the genus Zootermopsis inhabit forested areas in western North America. To better understand the colony composition and breeding structure of Zootermopsis, we identified polymorphic microsatellite loci to use in population analysis. Microsatellite loci were isolated from Zootermopsis nevadensis nevadensis (Hagen); however, all primers amplified homologous loci in Zootermopsis angusticollis (Hagen) and Zootermopsis nevadensis nuttingi (Hagen). Twelve loci were polymorphic in one or more of the above subspecies and species. The number of alleles per locus ranged from one to six, with some allelic differences among subspecies and species. We are currently utilizing the microsatellite markers to investigate the population genetics of Zootermopsis.
Characterization of microsatellite loci in the house fly, Musca domestica L. (Diptera: Muscidae)
Authors: CHAKRABARTI SEEMANTI , KAMBHAMPATI SRINIVAS , GRACE TONY , ZUREK LUDEK
Published: November 2004

The house fly, Musca domestica L., is a cosmopolitan species with a capacity to transmit human pathogens. Here, we report on the development of polymorphic microsatellite loci for house flies and present preliminary results from four house fly subpopulations from Manhattan, Kansas. Twenty‐four microsatellite loci were isolated and characterized using DNA enriched for repeat sequences. Forty individuals from four locations in Kansas were assayed to identify for polymorphic loci. Eight loci were polymorphic with the number of alleles ranging from three to six.
Characterization of polymorphic microsatellites in the Pacific sardine Sardinops sagax sagax (Clupeidae)
Authors: PEREYRA R. T. , SAILLANT E. , PRUETT C. L. , C. E. REXROAD III  , ROCHA‐OLIVARES A. , GOLD J. R.
Published: November 2004

We isolated 11 microsatellites from the Pacific sardine Sardinops sagax sagax. The number of alleles and HE among 30 individuals from a single population ranged from four to 24 and from 0.606 to 0.959, respectively. Pacific sardines are a vital economic resource in the northeastern Pacific Ocean, but insufficiently polymorphic loci have limited inferences about its stock structure and genetic variation. The level of variability of these new markers will prove useful in testing hypotheses on the stock‐structure and long‐term genetic integrity of the species.
Genomic and cDNA microsatellites from apricot (Prunus armeniaca L.)
Authors: HAGEN L. S. , CHAIB J. , FADY B. , DECROOCQ V. , BOUCHET J. P. , LAMBERT P. , AUDERGON J. M.
Published: November 2004

We developed primers for the amplification of 24 polymorphic nuclear microsatellites in apricot (Prunus armeniaca L.). Thirteen loci originated from three genomic libraries enriched for TC, TG and AAG motifs. Eight loci were developed from three fruit EST (Expressed‐Sequence‐Tag) libraries and three from a leaf cDNA microsatellite‐enriched library. There were up to nine alleles per polymorphic locus in 12 different cultivars. No difference in allele numbers were shown between cDNA and genomic‐source loci. Mean expected heterozygosity was 0.65 (range: 0.15–0.87). Mendelian segregation was confirmed for all loci. These markers should be helpful for diversity studies, genome mapping and cultivar identification in apricot and related species.
Characterization and cross‐species amplification of microsatellite markers in cherimoya (Annona cherimola Mill., Annonaceae)
Authors: ESCRIBANO P. , VIRUEL M. A. , HORMAZA J. I.
Published: November 2004

Fifteen polymorphic microsatellites were developed using a CT/AG‐enriched genomic library of cherimoya cv. Fino de Jete and screened on 23 genotypes from different geographical areas. This is the first set of microsatellites developed in Annonaceae. Fourteen of the microsatellites detected a single locus and only one detected two loci. The number of alleles in the single locus microsatellites ranged from two to six and the observed and expected heterozygosity ranged from 0.17 to 0.61 and from 0.12 to 0.76, respectively. Most of the simple sequence repeats were transferable to other species in the family.
Isolation and characterization of microsatellite markers in hoary marmots (Marmota caligata)
Authors: KYLE C. J. , KARELS T. J. , CLARK B. , STROBECK C. , HIK D. S. , DAVIS C. S.
Published: November 2004

Microsatellite loci were developed from hoary marmots (Marmota caligata) to aid in the investigation of the social structure and mating system of this species. Seven of the microsatellite loci developed were found to be moderately polymorphic with between two and seven alleles per locus. In addition to the microsatellites developed in hoary marmots we also tested markers developed for other scuirids, namely European alpine marmots (M. marmota), Columbian ground squirrels (Spermophilus columbianus) and European ground squirrels (S. citellus). Of these markers, 13 were polymorphic when amplified in hoary marmots with between two and nine alleles per locus.
Oestrogens and the skin
Authors: Brincat Mark P
Published: November 2004

Oestrogen loss at the menopause has a profound influence on skin. Oestrogen treatment in post‐menopausal women has repeatedly been shown to increase collagen content, dermal thickness and elasticity. Data on the effect of oestrogen on skin water content are also promising. Further, physiological studies on oestrogen and wound healing suggest that hormone replacement therapy (HRT) may play a beneficial role in cutaneous injury repair. Results of the effect of HRT on other physiological characteristics of skin, such as elastin content, sebaceous secretions, wrinkling and blood flow, are discordant. Given the responsiveness of skin to oestrogen, the effects of HRT on ageing skin require further examination and careful molecular studies will probably clarify oestrogen's effects at the cellular level.
Complexity and interprofessional education
Authors: Cooper Helen , Braye Suzy , Geyer Robert
Published: November 2004

Calls for greater collaboration between professionals in health and social care have led to pressures to move towards interprofessional education at both pre‐ and postregistration levels. Whilst this move has evolved out of ‘common sense’ demands, such a multiple systems approach to education does not fit easily into existing traditional disciplinary frameworks and there is, as yet, no proven theoretical framework to guide its development. What is more, it lacks a clear causality and predictability and therefore does not fit easily into traditional scientific frameworks with their focus on analysis, prediction and control. This article considers how complexity theory, with its focus on connectivity, diversity, self‐organization, and emergence, can provide interprofessional education with a coherent theoretical foundation, freeing it from the constraints of a traditional linear framework, enabling it to be better understood, questioned and challenged as a new paradigm of learning.
What factors determine where invertebrate‐feeding birds forage in dry agricultural grasslands?
Authors: ATKINSON PHILIP W. , BUCKINGHAM DAVID , MORRIS ANTONY J.
Published: November 2004

Increases in the intensity of the management of agricultural grasslands over the past 50 years have reduced plant species diversity in swards and increased uniformity in structure through changes in fertilizer regimes, grazing and mowing practices. These factors, as well as increased disturbance and trampling, have reduced the number and diversity of forbs and thus the diversity and abundance of invertebrates, in particular of foliar species. Associated with these changes in management, there has been a large decline in the abundance of many species of farmland birds in pastoral areas and more local extinctions compared with arable areas. To understand the impact of these management changes on bird populations, and design measures to reverse the declines, it is necessary to identify the key factors influencing bird usage of fields. We review results from five studies, which have related fertilizer and grazing management to bird usage of grass fields. Species that fed on soil invertebrates tended to show a positive response to the amount of nitrogen fertilizer added and increased grazing pressure, although there was a high degree of correlation between these two variables. In summer, many species, including corvids, Common Blackbird Turdus merula, Common Starling Sturnus vulgaris, Pied Wagtail Motacilla alba and Hedge Accentor Prunella modularis, showed a negative relationship with sward height, and in winter more species showed a positive relationship with bare ground. Taller sward heights are associated with a greater abundance and diversity of bird invertebrate food resources, and accessibility of food items or a lower risk of predation (actual or perceived) are likely to be the reasons for birds choosing to forage on shorter swards and in areas with more bare ground. Birds feeding on soil invertebrates were found to be generally tolerant of modern management practices that maintain short swards short, as accessibility to the soil has been increased. Species that feed on foliar invertebrates or forb seeds have been affected negatively by modern grassland agricultural practices.
Evidence for the indirect effects of pesticides on farmland birds
Authors: BOATMAN NIGEL D. , BRICKLE NICHOLAS W. , HART JUSTIN D. , MILSOM TIM P. , MORRIS ANTONY J. , MURRAY ALISTAIR W. A. , MURRAY KATHRYN A. , ROBERTSON PETER A.
Published: November 2004

Indirect effects of pesticides, operating through the food chain, have been proposed as a possible causal factor in the decline of farmland bird species. To demonstrate such a link, evidence is needed of (1) an effect of food abundance on breeding performance or survival; (2) an effect of breeding performance or survival on population change; and (3) pesticide effects on food resources, sufficient to reduce breeding performance or survival, and hence to affect the rate of population change. Evidence under all three categories is only available for one species, the Grey PartridgePerdix perdix, although data showing effects of pesticides on food resources and relationships between food resources and breeding performance are also available for some other species. This paper reports on recent work investigating the effects of pesticides on YellowhammerEmberiza citrinellaand SkylarkAlauda arvensisduring the breeding season. The probability of brood reduction in Yellowhammer was affected by the proportion of the foraging area around the nest which was sprayed with insecticide. No significant effects of pesticides were recorded on Skylark chick condition or growth rate, but sample sizes were small. Invertebrate food abundance affected chick condition (Skylark) and the number of chicks fledging (Yellowhammer and Corn BuntingMiliaria calandra; relationship for the latter derived from re‐analysis of data from an earlier study). Other recent work is briefly reviewed and the current evidence for the indirect effects of pesticides is summarized. Significant knowledge gaps are identified and some of the issues involved in resolving these are discussed.
Science into policy: the role of research in the development of a recovery plan for farmland birds in England
Authors: GRICE PHIL , EVANS ANDY , OSMOND JOHN , BRAND‐HARDY RICHARD
Published: November 2004

The results of scientific research have played a central role in convincing decision‐makers of the plight of farmland birds and in the development of land management measures and policies designed to reverse the population declines. Several types of study have contributed to what is now a considerable knowledge base on the ecological requirements of key species, the reasons for their declines and the remedial measures necessary to bring about population recovery. They include: monitoring; analyses of large‐scale datasets; detailed studies of particular species, land‐uses or land management practices; and the development and testing of solutions. As a consequence, there is now an excellent qualitative understanding of farmland bird ecology, which is well reflected in the suite of land management schemes and other policy initiatives that currently operate in England. Future research efforts should focus on the further development and testing of solutions and gaining a better understanding of the quantitative relationship between the provision of resources (especially nesting and foraging habitats) and the population response of target bird species. Such work should ensure that land management measures are deployed at the required scale, in appropriate locations and are of sufficient quality to influence the national populations of the declining species.
Policy into practice: the development and delivery of agri‐environment schemes and supporting advice in England
Authors: SMALLSHIRE DAVID , ROBERTSON PETER , THOMPSON PETER
Published: November 2004

There has been significant progress in recent years in translating the knowledge gained from farmland bird research into mechanisms which deliver sympathetic farm management. This progress is described for England, focusing on the development, targeting and delivery of agri‐environment schemes and supporting advisory materials and services. Following the successful implementation and evaluation of the Arable Stewardship Pilot Scheme, modified arable land management options were introduced into the Countryside Stewardship Scheme in 2002, targeted at scarce farmland birds and other threatened farmland wildlife. An enhanced suite of options will be introduced in 2005 in a new scheme, Environmental Stewardship, encompassing both simple ‘Entry Level’ and more demanding ‘Higher Level’ options. The former were piloted successfully in 2003, while the latter will replace existing schemes and focus more on defined environmental outcomes. The valuable synergies and contributions of partnerships in developing, targeting and evaluating schemes is acknowledged. Recognizing the targeting value of recent distribution data for declining farmland bird species, a project is underway to collate recent records and to make interpreted data accessible to farmers and their advisers. Appropriate advisory materials and demonstration sites have been used to engage and motivate farmers, by providing feedback, a sense of pride and better public appreciation. Examples of best practice in knowledge transfer are given: individually tailored advice and the use of suitable demonstration farms are very powerful mechanisms for achieving environmental results, but are costly. The policy and advisory infrastructure currently in place, across and between government and the voluntary sector, provides an unprecedented basis for an optimistic outlook for farmland birds.
ACCESSORY MINERALS AS TRACERS IN THE PROVENANCING OF ARCHAEOLOGICAL MARBLES, USED IN COMBINATION WITH ISOTOPIC AND PETROGRAPHIC DATA*
Authors: CAPEDRI S. , VENTURELLI G.
Published: November 2004

Thirty‐eight archaeological marbles (Roman and medieval) from Modena and Reggio Emilia (northern Italy) were provenanced using the accessory minerals as tracers and the results were compared with those inferred for the same artefacts using isotope composition and MGS (maximum grain size of calcite grains). The number of inferred possible sources is generally lower when using the mineralogical method, which therefore seems to be suited to marble provenancing.
INVESTIGATION ON ROMAN LEAD GLAZE FROM CANOSA: RESULTS OF CHEMICAL ANALYSES*
Authors: BENEDETTO G. E. DE , ACQUAFREDDA P. , MASIERI M. , QUARTA G. , SABBATINI L. , ZAMBONIN P. G. , TITE M. , WALTON M.
Published: November 2004

Five sherds of green glazed pottery excavated at Canosa (Apulia) in Italy have been analysed by scanning electron microscopy. The aim of the investigation was to determine the chemical composition of the glazes and thus obtain information on the methods used in their production. The glazes were all of the high‐lead type, coloured green by the addition of copper. Intermediate layers, observed at the interface between the glaze and body and giving the appearance of an applied white slip, were the result of the crystallization of lead feldspar from the molten glaze. Non‐calcareous clays were used in the production of the pottery bodies. Concentration profiles from the glaze exterior to the body suggested that the glazes were produced by applying a suspension consisting of lead oxide plus silica to the bodies. On the basis of the glaze and body compositions, it is suggested that the Canosa glazed pottery was produced locally.
A LEAD ISOTOPE DATABASE: THE LOS PEDROCHES – ALCUDIA AREA (SPAIN); IMPLICATIONS FOR ARCHAEOMETALLURGICAL CONNECTIONS ACROSS SOUTHWESTERN AND SOUTHEASTERN IBERIA*
Authors: SANTOS ZALDUEGUI J. F. , GARCÍA DE MADINABEITIA S. , GIL IBARGUCHI J. I. , PALERO F.
Published: November 2004

One hundred and twenty‐five new lead isotopic analyses on galena, mainly from the Los Pedroches – Alcudia Valley area of southern Iberia, are presented. These data allow us to define four compositional groups in the 207Pb/206Pb versus 208Pb/206Pb and 207Pb/206Pb versus 206Pb/204Pb diagrams. Group I compositions are intermediate between those previously reported for southeastern and southwestern Iberian ore mineral locations. The compositions of Group II, the largest group, overlap with ore data from southwestern Spain. Groups III and IV have compositions that have never before been identified in this region and are comparable to those from the Sardinian Cu ores, which might explain the previously assumed exotic origin for local Bronze Age artefacts.
THE COMPLEMENTARY USE OF NEUTRONS AND X‐RAYS FOR THE NON‐DESTRUCTIVE INVESTIGATION OF ARCHAEOLOGICAL OBJECTS FROM SWISS COLLECTIONS*
Authors: DESCHLER‐ERB E. , LEHMANN E. H. , PERNET L. , VONTOBEL P. , HARTMANN S.
Published: November 2004

This paper shows the possibilities offered by the combined use of non‐destructive neutron and X‐ray beams in archaeological research on metallic finds. The following five artefacts from Swiss excavations were submitted to investigation, each with dedicated aims: a Roman sword, a Roman dagger, an Iron Age bucket, Iron Age spearheads and a Roman finger ring. The images obtained with both methods—neutrons and X‐rays—are discussed in length in this paper. The investigations took place at the Paul Scherrer Institute and the archaeologists who studied the objects come from the Universities of Lausanne and Zurich.
Effects of Gravity, Shear and Surface Tension in Internal Condensing Flows: Results From Direct Computational Simulations
Authors: Liang Q. , Wang X. , Narain A.
Published: November 2004

The paper presents accurate numerical solutions of the full two-dimensional governing equations for steady and unsteady laminar/laminar internal condensing flows. The results relate to issues of better design and integration of condenser-sections in thermal management systems (looped heat pipes, etc.). The flow geometry, in normal or zero gravity, is chosen to be the inside of a channel with film condensation on one of the walls. In normal gravity, film condensation is on the bottom wall of a tilted (from vertical to horizontal) channel. It is found that it is important to know whether the exit conditions are constrained or unconstrained because nearly incompressible vapor flows occur only for exit conditions that are unconstrained. For the incompressible vapor flow situations, a method for computationally obtaining the requisite exit condition and associated stable steady/quasi-steady solutions is given here and the resulting solutions are shown to be in good agreement with some relevant experimental data for horizontal channels. These solutions are shown to be sensitive to the frequency and amplitude of the various Fourier components that represent the ever-present and minuscule transverse vibrations (standing waves) of the condensing surface. Compared to a vertical channel in normal gravity, shear driven zero gravity cases have much larger pressure drops, much slower wave speeds, much larger noise sensitive wave amplitudes that are controlled by surface tension, and narrower flow regime boundaries within which vapor flow can be considered incompressible. It is shown that significant enhancement in wave-energy and/or heat-transfer rates, if desired, are possible by designing the condensing surface noise to be in resonance with the intrinsic waves.
Solutions for Temperature Rise in Stationary/Moving Bodies Caused by Surface Heating With Surface Convection
Authors: Liu Shuangbiao , Lannou Sylvie , Wang Qian , Keer Leon
Published: November 2004

Determining the temperature rise of contact interfaces subject to surface heating is essential to controlling thermally induced failures in manufacturing processes and tribology. This paper provides a summary of solutions to problems of a stationary/moving half-space or half-plane without/with surface convection. In the first two sections, basic formulations for bodies with negligible surface convection are grouped as explicitly and completely as possible in terms of the Green’s function, the influence coefficients, and the frequency response function. In the final section, the influence coefficients are applied to solve surface-heating problems with surface convection. The time required to reach approximately steady state is found for bodies subject to a unit heat flux. The effect of convection is found to be dependent on the Pe´clet number and location.
Pressure Drop During Refrigerant Condensation Inside Horizontal Smooth, Helical Microfin, and Herringbone Microfin Tubes
Authors: Olivier Jonathan A. , Liebenberg Leon , Kedzierski Mark A. , Meyer Josua P.
Published: November 2004

This paper presents a study of pressure drops during condensation inside a smooth, an 18-deg helical microfin, and a herringbone microfin tube. Measurements were conducted with refrigerant flowing through the tube of a concentric heat exchanger, with water flowing in a counterflow direction in the annulus. Each tube was part of a condenser consisting of eight subcondensers with instrumentation preceding each subcondenser. Three refrigerants were used, namely, R-22, R-407C, and R-134a, all operating at a saturation temperature of 40 °C with mass fluxes ranging from 400 to 800kg/m2 s. Inlet qualities ranged from 0.85 to 0.95 and outlet qualities ranged from 0.05 to 0.15. The test results showed that on average for the three refrigerants the pressure gradients of the herringbone microfin tube were about 79% higher than that of the smooth tube and about 27% higher than that of the helical microfin tube. Further, a correlation from the literature for predicting pressure drops inside a helical microfin tube was modified for the herringbone microfin tube. The modified correlation predicted the data to within an error of 1% and had an absolute mean deviation of 6.8%. This modified correlation compared well with a correlation from the literature that predicted the data to within an error of 7%.
Effects of Periodic Structures on the Coherence Properties of Blackbody Radiation
Authors: Hu L. , Schmidt A. , Narayanaswamy A. , Chen G.
Published: November 2004

Radiative properties have been studied for one-dimensional dielectric multilayer structures subjected to blackbody radiation sources. The total hemispherical transmittances are calculated for periodic structures and structures with random variation in layer thickness, using wave-optics and ray-tracing methods. Simulation results show that for periodic structures, the transmittance calculated using wave optics approaches a nonzero constant value with an increasing number of layers, while the transmittance obtained using the ray-tracing method asymptotically approaches zero. For random structures, the transmittance given by wave optics drops to zero at different rates depending on the order of random variations in layer thickness. It is found that the wave interference effect always plays a role when dealing with multilayer structures. The results are explained based on extended and localized waves.
Three-Dimensional Forced Convection in Plane Symmetric Sudden Expansion
Authors: Nie and J. H. , Armaly B. F.
Published: November 2004

Simulations of three-dimensional laminar forced convection in a plane symmetric sudden expansion are presented for Reynolds numbers where the flow is steady and symmetric. A swirling “jetlike” flow develops near the sidewalls in the separating shear layer, and its impingement on the stepped wall is responsible for the maximum that develops in the Nusselt number adjacent to the sidewalls and for the reverse flow that develops in that region. The maximum Nusselt number on the stepped wall is located inside the primary recirculation flow region and its location does not coincide with the jetlike flow impingement region. The results reveal that the location where the streamwise component of wall shear stress is zero on the stepped walls does not coincide with the outer edge of the primary recirculation flow region near the sidewalls.
An Experimental Correlation for Combined Convection and Radiation Between Parallel Vertical Plates
Authors: Krishnan A. S. , Balaji C. , Venkateshan S. P.
Published: November 2004

Results of an experimental study of natural convection and surface radiation between three parallel vertical plates, symmetrically spaced, with air as the intervening medium are presented. The analysis consists of heating the central plate at different levels and recording the temperatures of both the central and the side plates at steady state conditions. Based on the measurements, a correlation for the maximum temperature excess of the “hot” plate in terms of the emissivity of the central and the side plates, the aspect ratio, and the dimensionless total heat flux is given, valid for a range of emissivity 0.05⩽εc,εs⩽0.85, aspect ratio 2.38⩽A⩽17, and total heat flux 32⩽q⩽1590 W/m2. Through this, the heat transfer enhancement due to radiation has been succinctly brought out.
Second Law Based Optimization of Falling Film Single Tube Absorption Generator
Authors: Jani S. , Saidi M. H. , Mozaffari A. A.
Published: November 2004

The objective of this paper is to provide optimization of falling film LiBr solution on a horizontal single tube based on minimization of entropy generation. Flow regime is considered to be laminar. The effect of boiling has been ignored and wall temperature is constant. Velocity, temperature and concentration distributions are numerically determined and dimensionless correlations are obtained to predict the average heat transfer coefficient and average evaporation factor on the horizontal tube. Thermodynamic imperfection due to passing lithium bromide solution is attributed to nonisothermal heat transfer; fluid flow friction and mass transfer irreversibility. Scale analysis shows that the momentum and mass transfer irreversibilities can be ignored at the expense of heat transfer irreversibility. In the process of optimization, for a specified evaporation heat flux, the entropy generation accompanying the developed dimensionless heat and mass transfer correlations has been minimized and the optimal geometry and the optimum thermal hydraulic parameters are revealed. The investigation cited here indicates the promise of entropy generation minimization as an efficient design and optimization tool.
On the Necessity of Positive Semi-Definite Conductivity and Onsager Reciprocity in Modeling Heat Conduction in Anisotropic Media
Authors: Powers Joseph M.
Published: November 2004

It is demonstrated by a concise standard derivation, motivated by principles of rational continuum mechanics and irreversible thermodynamics augmented by novel detailed examples, that for heat conduction in linearly anisotropic solids: (1) common restrictions placed on the form of the thermal conductivity tensor are insufficient to guarantee satisfaction of the second law of thermodynamics, and (2) satisfaction of the first and second laws of thermodynamics alone is still insufficient to insure agreement between heat flow predictions and observation. An additional constraint beyond that given in many standard studies, namely that all three principal invariants of the conductivity tensor be positive semi-definite, is imposed in order to guarantee satisfaction of the entropy inequality. Thus constrained, such a theory remains under-restricted and can admit purely cyclic heat fluxes, which are not observed in nature. Imposition of the conjectures of Duhamel and Stokes, which are in fact earlier specific incarnations of Onsager’s reciprocity theory, on the constitutive model relating heat flux to temperature gradient is a sufficient remedy.
The Nonlinear Increase of Nusselt Number With Friction Factor in Fully Developed Laminar Duct Flow
Authors: Van den Bulck E.
Published: November 2004

This paper deals with heat transfer in fully developed laminar flow in cylindrical ducts. For this type of flow, the product of friction factor with Reynolds number f Re and the Nusselt number are both constants. It is known that the Nusselt number increases with the shift of boundary condition from constant wall temperature to constant heat flux. Also, the ratio of the Nusselt number to f Re increases when the convexity of the duct is reduced, e.g., a cylinder visavis parallel plates. This paper gives a simple physical explanation for these two phenomenona.
KatG Is the Primary Detoxifier of Hydrogen Peroxide Produced by Aerobic Metabolism in
Bradyrhizobium japonicum
Authors: Panek Heather R. , O'Brian Mark R.
Published: November 2004

Bacteria are exposed to reactive oxygen species from the environment and from those generated by aerobic metabolism. Catalases are heme proteins that detoxify H
2
O
2
, and many bacteria contain more than one catalase enzyme. Also, the nonheme peroxidase alkyl hydroperoxide reductase (Ahp) is the major scavenger of endogenous H
2
O
2
in
Escherichia coli
. Here, we show that aerobically grown
Bradyrhizobium japonicum
cells express a single catalase activity. Four genes encoding putative catalases in the
B. japonicum
genome were identified, including a
katG
homolog encoding a catalase-peroxidase. Deletion of the
katG
gene resulted in loss of catalase activity in cell extracts and of exogenous H
2
O
2
consumption by whole cells. The
katG
strain had a severe aerobic growth phenotype but showed improved growth in the absence of O
2
. By contrast, a
B. japonicum ahpCD
mutant grew well aerobically and consumed H
2
O
2
at wild-type rates. A heme-deficient
hemA
mutant expressed about one-third of the KatG activity as the wild type but grew well aerobically and scavenged low concentrations of exogenous H
2
O
2
. However, cells of the
hemA
strain were deficient in consumption of high concentrations of H
2
O
2
and were very sensitive to killing by short exposure to H
2
O
2
. In addition, KatG activity did not decrease as a result of mutation of the gene encoding the transcriptional activator OxyR. We conclude that aerobic metabolism produces toxic levels of H
2
O
2
in
B. japonicum
, which is detoxified primarily by KatG. Furthermore, the
katG
level sufficient for detoxification does not require OxyR.
Purification and Initial Characterization of the
Salmonella enterica
PduO ATP:Cob(I)alamin Adenosyltransferase
Authors: Johnson Celeste L. V. , Buszko Marian L. , Bobik Thomas A.
Published: November 2004

The PduO enzyme of
Salmonella enterica
is an ATP:cob(I)alamin adenosyltransferase that catalyzes the final step in the conversion of vitamin B
12
to coenzyme B
12
. The primary physiological role of this enzyme is to support coenzyme B
12
-dependent 1,2-propanediol degradation, and bioinformatic analysis has indicated that it has two domains. Here the PduO adenosyltransferase was produced in
Escherichia coli
, solubilized from inclusion bodies, purified to apparent homogeneity, and partially characterized biochemically. The

K
m

values of PduO for ATP and cob(I)alamin were 19.8 and 4.5 μM, respectively, and the enzyme
V
max
was 243 nmol min
−1
mg of protein
−1
. Further investigations showed that PduO was active with ATP and partially active with deoxy-ATP, but lacked measurable activity with other nucleotides.
31
P nuclear magnetic resonance established that triphosphate was a product of the PduO reaction, and kinetic studies indicated a ternary complex mechanism. A series of truncated versions of the PduO protein were produced in
Escherichia coli
, partially purified, and used to show that adenosyltransferase activity is associated with the N-terminal domain. The N-terminal domain was purified to near homogeneity and shown to have biochemical properties and kinetic constants similar to those of the full-length enzyme. This indicated that the C-terminal domain was not directly involved in catalysis or substrate binding and may have another role.
Positive and Negative Transcriptional Regulators of Glutathione-Dependent Formaldehyde Metabolism
Authors: Hickman Jason W. , Witthuhn Vernon C. , Dominguez Miguel , Donohue Timothy J.
Published: November 2004

A glutathione (GSH)-dependent pathway is used for formaldehyde metabolism by a wide variety of prokaryotes and eukaryotes. In this pathway,S-hydroxymethylglutathione, produced by the reaction of formaldehyde with the thiolate moiety of glutathione, is the substrate for a GSH-dependent formaldehyde dehydrogenase (GSH-FDH). While expression of GSH-FDH often increases in the presence of metabolic or exogenous sources of formaldehyde, little is known about the factors that regulate this response. Here, we identify two signal transduction pathways that regulate expression ofadhI, the gene encoding GSH-FDH, inRhodobacter sphaeroides. The loss of the histidine kinase response regulator pair RfdRS or the histidine kinase RfdS increasesadhItranscription in the absence of metabolic sources of formaldehyde. Cells lacking RfdRS further increaseadhIexpression in the presence of metabolic sources of formaldehyde (methanol), suggesting that this negative regulator of GSH-FDH expression does not respond to this compound. In contrast, mutants lacking the histidine kinase response regulator pair AfdRS or the histidine kinase AfdS cannot induceadhIexpression in the presence of either formaldehyde or metabolic sources of this compound. AfdR stimulates activity of theadhIpromoter in vitro, indicating that this protein is a direct activator of GSH-FDH expression. Activation by AfdR is detectable only after incubation of the protein with acetyl phosphate, suggesting that phosphorylation is necessary for transcription activation. Activation ofadhItranscription by acetyl-phosphate-treated AfdR in vitro is inhibited by a truncated RfdR protein, suggesting that this protein is a direct repressor of GSH-FDH expression. Together, the data indicate that AfdRS and RfdRS positively and negatively regulateadhItranscription in response to different signals.
Global Transposon Mutagenesis and Essential Gene Analysis of
Helicobacter pylori
Authors: Salama Nina R. , Shepherd Benjamin , Falkow Stanley
Published: November 2004

We have constructed a genome-saturating mutant library of the human gastric pathogen
Helicobacter pylori
. Microarray tracking of transposon mutants (MATT) allowed us to map the position of 5,363 transposon mutants in our library. While we generally found insertions well distributed throughout the genome, 344 genes had no detectable transposon insertions, and this list is predicted to be highly enriched for essential genes. Comparison to the essential gene set of other bacteria revealed a surprisingly limited overlap with all organisms tested (11%), while 55% were essential in some organisms but not others. We independently verified the essentiality of several gene products, including an HtrA family serine protease, a hypothetical protein with putative phospholipase D activity, and a riboflavin specific deaminase. A limited screen for motility mutants allowed us to estimate that 4.5% of the genome is dedicated to this virulence-associated phenotype.
Systematic Inactivation and Phenotypic Characterization of Two-Component Signal Transduction Systems ofEnterococcus faecalisV583
Authors: Hancock Lynn E. , Perego Marta
Published: November 2004

The ability of enterococci to adapt and respond to different environmental stimuli, including the host environment, led us to investigate the role of two-component signal transduction in the regulation ofEnterococcus faecalisphysiology. Using a bioinformatic approach, we previously identified 17 two-component systems (TCS), consisting of a sensory histidine kinase and the cognate response regulator, as well as an additional orphan response regulator (L. E. Hancock and M. Perego, J. Bacteriol. 184:5819-5825, 2002). In an effort to identify the potential function of each TCS in the biology ofE. faecalisclinical isolate strain V583, we constructed insertion mutations in each of the response regulators. We were able to inactivate 17 of 18 response regulators, the exception being an ortholog of YycF, previously shown to be essential for viability in a variety of gram-positive microorganisms. The biological effects of the remaining mutations were assessed by using a number of assays, including antibiotic resistance, biofilm formation, and environmental stress. We identified TCS related to antibiotic resistance and environmental stress and found one system which controls the initiation of biofilm development byE. faecalis.
Sequence Tolerance of the Phage λ
P
RM
Promoter: Implications for Evolution of Gene Regulatory Circuitry
Authors: Michalowski Christine B. , Short Megan D. , Little John W.
Published: November 2004

Much
of the gene regulatory circuitry of phage λ
centers on a complex region called the
O
R
region. This ∼100-bp region is densely
packed with regulatory sites, including two promoters and three
repressor-binding sites. The dense packing of this region is likely to
impose severe constraints on its ability to change during evolution,
raising the question of how the specific arrangement of sites and their
exact sequences could evolve to their present form. Here we ask whether
the sequence of a
cis
-acting site can be widely varied while
retaining its function; if it can, evolution could proceed by a larger
number of paths. To help address this question, we developed aλ
cloning vector that allowed us to clone fragments spanning
the
O
R
region. By using this vector, we carried out
intensive mutagenesis of the
P
RM
promoter, which
drives expression of CI repressor and is activated by CI itself. We
made a pool of fragments in which 8 of the 12 positions in the−
35 and −10 regions were randomized and cloned this
pool into the vector, making a pool of
P
RM
variant
phage. About 10% of the
P
RM
variants were
able to lysogenize, suggesting that the λ regulatory circuitry
is compatible with a wide range of
P
RM
sequences.
Analysis of several of these phages indicated a range of behaviors in
prophage induction. Several isolates had induction properties
similar to those of the wild type, and their promoters resembled the
wild type in their responses to CI. We term this property of different
sequences allowing roughly equivalent function “sequence
tolerance ” and discuss its role in the evolution of gene
regulatory
circuitry.
Kinetic Analysis of the Oxidative Conversion of the [4Fe-4S]
2+
Cluster of FNR to a [2Fe-2S]
2+
Cluster
Authors: Sutton Victoria R. , Mettert Erin L. , Beinert Helmut , Kiley Patricia J.
Published: November 2004

The ability of FNR to sense and respond to cellular O
2
levels depends on its [4Fe-4S]
2+
cluster. In the presence of O
2
, the [4Fe-4S]
2+
cluster is converted to a [2Fe-2S]
2+
cluster, which inactivates FNR as a transcriptional regulator. In this study, we demonstrate that ∼2 Fe
2+
ions are released from the reaction of O
2
with the [4Fe-4S]
2+
cluster. Fe
2+
release was then used as an assay of reaction progress to investigate the rate of [4Fe-4S]
2+
to [2Fe-2S]
2+
cluster conversion in vitro. We also found that there was no detectable difference in the rate of O
2
-induced cluster conversion for FNR free in solution compared to its DNA-bound form. In addition, the rate of FNR inactivation was monitored in vivo by measuring the rate at which transcriptional regulation by FNR is lost upon the exposure of cells to O
2
; a comparison of the in vitro and in vivo rates of conversion suggests that O
2
-induced cluster conversion is sufficient to explain FNR inactivation in cells. FNR protein levels were also compared for cells grown under aerobic and anaerobic conditions.
Novel Roles for the AIDA Adhesin from DiarrheagenicEscherichia coli: Cell Aggregation and Biofilm Formation
Authors: Sherlock Orla , Schembri Mark A. , Reisner Andreas , Klemm Per
Published: November 2004

Diarrhea-causingEscherichia colistrains are responsible for numerous cases of gastrointestinal disease and constitute a serious health problem throughout the world. The ability to recognize and attach to host intestinal surfaces is an essential step in the pathogenesis of such strains. AIDA is a potent bacterial adhesin associated with some diarrheagenicE. colistrains. AIDA mediates bacterial attachment to a broad variety of human and other mammalian cells. It is a surface-displayed autotransporter protein and belongs to the selected group of bacterial glycoproteins; only the glycosylated form binds to mammalian cells. Here, we show that AIDA possesses self-association characteristics and can mediate autoaggregation ofE. colicells. We demonstrate that intercellular AIDA-AIDA interaction is responsible for bacterial autoaggregation. Interestingly, AIDA-expressing cells can interact with antigen 43 (Ag43)-expressing cells, which is indicative of an intercellular AIDA-Ag43 interaction. Additionally, AIDA expression dramatically enhances biofilm formation byE. colion abiotic surfaces in flow chambers.