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1Latest Papers from Table of Contents or Articles in PressC. Gieger ; A. Radhakrishnan ; A. Cvejic ; W. Tang ; E. Porcu ; G. Pistis ; J. Serbanovic-Canic ; U. Elling ; A. H. Goodall ; Y. Labrune ; L. M. Lopez ; R. Magi ; S. Meacham ; Y. Okada ; N. Pirastu ; R. Sorice ; A. Teumer ; K. Voss ; W. Zhang ; R. Ramirez-Solis ; J. C. Bis ; D. Ellinghaus ; M. Gogele ; J. J. Hottenga ; C. Langenberg ; P. Kovacs ; P. F. O'Reilly ; S. Y. Shin ; T. Esko ; J. Hartiala ; S. Kanoni ; F. Murgia ; A. Parsa ; J. Stephens ; P. van der Harst ; C. Ellen van der Schoot ; H. Allayee ; A. Attwood ; B. Balkau ; F. Bastardot ; S. Basu ; S. E. Baumeister ; G. Biino ; L. Bomba ; A. Bonnefond ; F. Cambien ; J. C. Chambers ; F. Cucca ; P. D'Adamo ; G. Davies ; R. A. de Boer ; E. J. de Geus ; A. Doring ; P. Elliott ; J. Erdmann ; D. M. Evans ; M. Falchi ; W. Feng ; A. R. Folsom ; I. H. Frazer ; Q. D. Gibson ; N. L. Glazer ; C. Hammond ; A. L. Hartikainen ; S. R. Heckbert ; C. Hengstenberg ; M. Hersch ; T. Illig ; R. J. Loos ; J. Jolley ; K. T. Khaw ; B. Kuhnel ; M. C. Kyrtsonis ; V. Lagou ; H. Lloyd-Jones ; T. Lumley ; M. Mangino ; A. Maschio ; I. Mateo Leach ; B. McKnight ; Y. Memari ; B. D. Mitchell ; G. W. Montgomery ; Y. Nakamura ; M. Nauck ; G. Navis ; U. Nothlings ; I. M. Nolte ; D. J. Porteous ; A. Pouta ; P. P. Pramstaller ; J. Pullat ; S. M. Ring ; J. I. Rotter ; D. Ruggiero ; A. Ruokonen ; C. Sala ; N. J. Samani ; J. Sambrook ; D. Schlessinger ; S. Schreiber ; H. Schunkert ; J. Scott ; N. L. Smith ; H. Snieder ; J. M. Starr ; M. Stumvoll ; A. Takahashi ; W. H. Tang ; K. Taylor ; A. Tenesa ; S. Lay Thein ; A. Tonjes ; M. Uda ; S. Ulivi ; D. J. van Veldhuisen ; P. M. Visscher ; U. Volker ; H. E. Wichmann ; K. L. Wiggins ; G. Willemsen ; T. P. Yang ; J. Hua Zhao ; P. Zitting ; J. R. Bradley ; G. V. Dedoussis ; P. Gasparini ; S. L. Hazen ; A. Metspalu ; M. Pirastu ; A. R. Shuldiner ; L. Joost van Pelt ; J. J. Zwaginga ; D. I. Boomsma ; I. J. Deary ; A. Franke ; P. Froguel ; S. K. Ganesh ; M. R. Jarvelin ; N. G. Martin ; C. Meisinger ; B. M. Psaty ; T. D. Spector ; N. J. Wareham ; J. W. Akkerman ; M. Ciullo ; P. Deloukas ; A. Greinacher ; S. Jupe ; N. Kamatani ; J. Khadake ; J. S. Kooner ; J. Penninger ; I. Prokopenko ; D. Stemple ; D. Toniolo ; L. Wernisch ; S. Sanna ; A. A. Hicks ; A. Rendon ; M. A. Ferreira ; W. H. Ouwehand ; N. Soranzo
Nature Publishing Group (NPG)
Published 2011Staff ViewPublication Date: 2011-12-06Publisher: Nature Publishing Group (NPG)Print ISSN: 0028-0836Electronic ISSN: 1476-4687Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsKeywords: Animals ; Blood Platelets/*cytology/metabolism ; Cell Size ; Drosophila Proteins/genetics ; Drosophila melanogaster/genetics ; Europe ; Gene Expression Profiling ; Gene Silencing ; Genome, Human/genetics ; Genome-Wide Association Study ; Hematopoiesis/*genetics ; Humans ; Megakaryocytes/*cytology/metabolism ; Platelet Count ; Protein Interaction Maps ; Transcription, Genetic/genetics ; Zebrafish/genetics ; Zebrafish Proteins/geneticsPublished by: -
2Articles: DFG German National LicensesStaff View
ISSN: 1570-7458Keywords: Biocontrol ; natural enemies ; Glycine max ; Heliothis zea, corn earworm ; Heterodera glycines ; soybean cyst nematode ; pest complex ; weeds ; soybean ; survivalSource: Springer Online Journal Archives 1860-2000Topics: BiologyNotes: Abstract The influence of canopy development in soybean on the survival of corn earworm, Heliothis zea (Boddie) (Lepidoptera: Noctuidae), egg and larval stages and population dynamics of arthropod fauna were evaluated in field trials during 1986–88 in eastern North Carolina. Soybean canopy size decreased as soybean cyst nematode, Heterodera glycines Ichinohe (Nematoda: Heteroderidae), initial population densities increased. Plant species composition of the soybean canopy was affected by weed population densities. Mortality of H. zea larvae due to parasitism and infection with entomopathogens was greater in closed canopy and (or) weedy soybeans than in very open and (or) weed free soybeans. Predation and parasitism of corn earworm eggs were similar across nematode and weed density treatments. Natural enemy populations increased to highest levels during July in closed canopy and (or) weedy soybeans, coinciding with availability of largest prey population reservoirs. A delay in colonization of very open and (or) weed free soybeans by beneficial arthropods until mid to late August allowed greater H. zea larval survival than in closed canopy and (or) weedy soybeans. Arthropod species richness was generally greatest in closed canopy and (or) weedy soybeans during mid to late July, with differences becoming nonsignificant in August and early September. Mean and maximum ambient temperatures were higher and relative humidities lower in open canopy than in closed canopy plots. These conditions were less favorable for development of pathogens and natural enemies.Type of Medium: Electronic ResourceURL: -
3Articles: DFG German National LicensesSorenson, C. E. ; Kennedy, G. G. ; Duyn, W. ; Bradley, J. R. ; Walgenbach, J. F.
Springer
Published 1992Staff ViewISSN: 1570-7458Keywords: Insecta ; Ostrina nubilalis ; pheromone trapping ; maizeSource: Springer Online Journal Archives 1860-2000Topics: BiologyNotes: Abstract The response of male European corn borer, Ostrinia nubilalis (Hübner) to synthetic pheromone lures containing various isomeric blends of the sex pheromone 11-tetradecenyl acetate was measured in 13 counties in North Carolina. The blends consisted of either 3% Z (‘E strain’), 97% Z (‘Z strain’), or 35% Z (‘hybrid’) 11-tetradecenyl acetate. Response to E strain lures predominated in those counties located in the Coastal Plain (east) of the state, while response to the Z strain pheromone was dominant in the west. A zone of overlap of these broad strain distributions appears to occur in the eastern Piedmont. Within this zone there was substantial response to both E and Z blends. The proportion of these responses changed considerably between generations within years as well as between years. Significantly higher capture rates in hybrid baited traps in parts of the overlap zone may be indicative of increased rates of hybridization between the E and Z strains.Type of Medium: Electronic ResourceURL: -
4Articles: DFG German National LicensesEllsworth, P. C. ; Patterson, R. P. ; Bradley, J. R. ; Kennedy, G. G. ; Stinner, R. E.
Springer
Published 1989Staff ViewISSN: 1570-7458Keywords: European corn borer ; Ostrinia nubilalis ; maize ; water ; drought ; stress ; development ; models ; phytotron ; temperatureSource: Springer Online Journal Archives 1860-2000Topics: BiologyDescription / Table of Contents: Résumé Des plants de maïs se développent dans un phytotron dans 4 conditions d'humidité du sol (de la saturation à la dessication) et à 3 températures constantes (20°, 25° & 30°C). Chaque pied est contaminé au moment de l'émission du pollen, par une ooplaque d'O. nubilalis Hübn. (ECB) de race européenne E. L'installation, la colonisation et le développement des chenilles sont notés lors de 12 périodes de prélèvements destructifs (4 par température). La vitesse de développement d'O. nubilalis est affectée par la température, main non par l'humidité du sol. Les 4 niveaux d'humidité du sol n'ont aucun effet sur la teneur en eau des tiges de maïs. En fait, les feuilles de maïs présentent une senescence précoce lorsqu'il y a déficit en eau dans le sol. La teneur en eau du sol agit sur l'installation, sur la distribution verticale, la dispersion et le lieu d'alimentation des chenilles; mais ces effets sont légers et ne modifient pas la vitesse de développement. L'environnement larvaire dans la tige de maïs est efficacement isolé des variations externes par l'aptitude de la plante à maintenir la teneur en eau des tiges relativement élevée et stable. Ainsi, des changements importants au niveau du sol n'ont pratiquement pas d'effets sur le développement d'O. nubilalis, malgré les conséquences brutales pour la plante. Cette étude montre que la vitesse de développement d'O. nubilalis est relativement insensible aux modifications de la teneur en eau du sol ainsi qu'aux effets de ce stress de sécheresse sévère sur le pied de maïs. La discussion porte sur l'importance de ces résultats pour la modélisation de la dynamique de l'insecte, la physiologie de la culture et les interactions entre insecte et plante.Notes: Abstract Maize plants were grown under four moisture regimes (wet to extreme deficit) and three constant temperatures (20°, 25° & 30°C) in a phytotron. Each plant was infested with one E-race European corn borer [Ostrinia nubilalis (Hubn.)] (ECB) egg mass at pollen shed. ECB development, location, and establishment were recorded over the course of 12 destructive sample dates (4/temperature). ECB developmental rates were not significantly affected by soil moisture treatments, but were significantly affected by temperature. In spite of successful establishment of four distinctly different soil moisture regimes, the maize stalk tissue water levels were not significantly different among soil water treatments. Instead, the maize plants exhibited accelerated leaf senescence in response to the water deficit conditions. Among the soil water treatments, differences were found in larval establishment, vertical distribution and dispersion, and feeding site selection; however, those effects were slight and could not explain the similarity in ECB developmental rates observed in these treatments. In maize, the larval environment within the stalk was effectively insulated from changes in the external environment by the plant's ability to maintain a relatively high and stable stalk tissue water content. Thus, large changes to the soil environment had essentially no effect on ECB development, though drastic consequences for the plant. This study indicates that ECB rates of development are relatively insensitive to changes in the soil water environment as well as the associated changes in the maize plant that accompany severe drought stress. The significance of these findings to insect modelling, crop physiology, and insect-crop interactions is discussed.Type of Medium: Electronic ResourceURL: -
5Articles: DFG German National LicensesEllsworth, P. C. ; Bradley, J. R. ; Kennedy, G. G. ; Patterson, R. P. ; Stinner, R. E.
Springer
Published 1992Staff ViewISSN: 1570-7458Keywords: European corn borer ; Ostrinia nubilalis ; maize ; water ; drought ; stress ; development ; models ; microenvironment ; irrigationSource: Springer Online Journal Archives 1860-2000Topics: BiologyNotes: Abstract This study examined the impact of irrigation water on certain aspects of an insect-plant relationship in the field including the assessment of plant-mediated water effects on an herbivore's development, survival, and behavior, and plant damage parameters and host tissue water status. Maize (Zea mays L.) plants were arranged in a randomized complete block design in the field over two years in North Carolina (NC). Four blocks were subjected to three different irrigation treatments initiated ca. one week before anthesis: optimal, intermediate, deficit water supply. Each plant was infested with one (1986) or two (1987) black head stage, E-race European corn borer [Ostrinia nubilalis (Hübn.)] (ECB) egg masses at tasselling. ECB development, tunnelling site, and survival as well as plant tissue water status (tissue % water contents [θ] & leaf water potentials [Ψ]) were recorded through July. The irrigation effect on ECB parameters was slight and variable. Internal stalk temperatures of optimal plants were consistently cooler than their deficit counterparts (1 day-degree/day). With degree-days included as an explanatory variable in the analyses, there were no significant irrigation effects on the ECB parameters, except for total proportion of ECB's bored into maize plant parts. More ECB's bored into drier plants than in optimal plants; however, this trend was not significant in 1987. Plant water indices showed that though Ψ responded to irrigation, there were only minor changes in tissue θ, particularly in view of the larger diurnal tissue changes observed and the relatively high, sustained stalk θ levels seen over all treatments. Examination of ECB pupal θ confirmed that dietary water changes were minor or non-limiting to the insects' developmental physiology, because pupal θ was not sensitive to the irrigation treatments. Though water supply changes have drastic developmental and agronomic consequences for the maize plant, little or no changes were seen in the ECB feeding environment. Furthermore, a plant damage model was developed whereby the total % of ECB's tunnelled into maize was related to the mean larval age. The implications of this model on the understanding of ECB tunnelling behavior, damage potential, and pest management is noted.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesStaff View
ISSN: 1570-7458Keywords: insecta ; Ostrinia nubilalis ; egg distribution ; maizeSource: Springer Online Journal Archives 1860-2000Topics: BiologyNotes: Abstract The relationship between second generation European corn borer (Ostrinia nubilalis Hübner) egg mass numbers and subsequent field corn damage, as measured by stalk cavity numbers, was studied in 79 fields in northeastern North Carolina over three years. A mean of 0.028 egg masses per plant (645 egg masses/23400 plants) was found over the course of the study. Significant differences in oviposition rate were detected between fields and years. Ca. 85% of egg masses were deposited in a five leaf zone surrounding the primary ear; of these, 89% were found on the lower four leaves in this zone. Egg masses appeared to be distributed randomly within fields but at low rates of incidence, and oviposition was relatively uniform between sampling areas within individual fields. Under moderate to high oviposition pressure (mean number of egg masses per plant over the duration of the oviposition period 〉ca. 0.02), eggs laid during the early phases of the oviposition period account for more subsequent stalk damage than eggs laid during the later phases of the oviposition period. Variations in second generation egg mass numbers accounted for ca. 70% of variation in stalk cavity numbers.Type of Medium: Electronic ResourceURL: -
7Articles: DFG German National LicensesStaff View
ISSN: 1570-7458Keywords: larval establishment ; corn earworm ; Glycine max ; spin-down behaviorSource: Springer Online Journal Archives 1860-2000Topics: BiologyDescription / Table of Contents: Résumé Des expériences ont été réalisées dans deux types de conditions (avec ou sans possibilité de dispersion) pour déterminer si le taux d'installation des chenilles de premier stade de H. zea Bod. dépendait d'une mortalité liée au stade développement de Glycine max L. L'installation était considérée comme réussie quand les chenilles avaient atteint le second stade. Bien qu'il fût possible de distinguer les variétés de soja tant par le taux d'installation des chenilles que par les dégâts provoqués, les plantes les plus jeunes étaient plus colonisées par des chenilles que les témoins plus âgés. Toutes les variétés de soja à n'importe quel stade étaient acceptées lorsque la dispersion des chenilles était impossible. Avec possibilité de dispersion, les chenilles ont aussi accepté tous les stades phénologiques, mais en moins grands nombres que lorsque la dispersion était impossible. Le comportement de dispersion était beaucoup plus fréquent sur les plantes à port indéterminé que sur celles à port déterminé. Les possibilités de réinstallation après dispersion des chenilles de premier stade ont été limitées.Notes: Abstract Early instar Heliothis zea (Boddie) (Lepidoptera: Noctuidae) established on all stages of soybean (Glycine max [L.] Merrill) tested when larvae were confined to plants, although establishment decreased after podset stage and as seeds matured. In tests where larvae were allowed to disperse freely on plants, establishment also decreased as maturity increased, but was much lower in each stage than when confined to plants. Neonate larvae settled more quickly on terminals and expanding trifoliates than on mature trifoliates based on initiation of feeding and movement away from initial sites of placement. The ability of neonate larvae placed a short distance from soybean plants to reach a host was affected by high soil and ambient temperature. The results of these experiments suggest that larval host establishment and spin-down behavior play a major role in the late instar population distribution among soybean fields and that maturity of the host strongly influences that behavior.Type of Medium: Electronic ResourceURL: -
8Articles: DFG German National LicensesEllsworth, P. C. ; Umeozor, O. C. ; Kennedy, G. G. ; Bradley, J. R. ; Duyn, J. W.
Springer
Published 1989Staff ViewISSN: 1570-7458Keywords: European corn borer ; diapause ; voltinism ; seasonality ; phenology ; photoperiod ; models ; population dynamics ; black light trapSource: Springer Online Journal Archives 1860-2000Topics: BiologyDescription / Table of Contents: Résumé La diapause d'O. nubilalis Hubn. est décrite d'après des études en conditions naturelles et programmées de souches sauvages ou élevées au laboratoire en Caroline du Nord. La diapause est décrite comme une fonction de la photophase (heures de jour/24 heures) et du stade larvaire au début des conditions inductrices de la diapause. Une photophase critique de 14,4 h et un stade critique larvaire de 3,3 ont été établis au laboratoire après 3 ans d'études en insectarium. 7 ans de piégeage à la lumière noire à Goldsboro, ont montré la vraisemblance de l'existence de 4 vols par an. Les données sur la diapause de cet insecte sont utilisées pour expliquer tant le nombre de vols que l'importance relative des derniers vols. En moyenne, la majorité des lignées ont 3 générations par an, O. nubilalis précoces produisant une quatrième génération conséquente et prédictible. La data et l'importance du 4ème vol peuvent être partiellement expliquées d'après la photophase critique, et la data et la structure en âge des générations précédentes. La plupart des années, le 4ème vol est moins important que le 3ème par suite de la prédisposition à la diapause de la majorité de la 4ème génération. Cependant, dans un cas au moins, en 1977, le 4ème était anormalement important et pouvait être prédit par de faibles changements temporels dans les 3 précédents vols, détournant de la diapause la majorité des chenilles de 4ème génération. La discussion porte sur la valeur du modèle fourni par la diapause de O. nubilalis pour expliquer et prédire la dynamique des évéments phénologiques.Notes: Abstract The diapause biology of the European corn borer (ECB), Ostrinia nubilalis (Hübn.), is described based on natural and controlled environment studies of feral and lab-reared ECB's in North Carolina (NC). The diapause response is described as a function of photophase (h of light/day) as well as a function of larval age (instar) at onset of diapause-inducing conditions. A critical photophase of 14.4 h and a critical mean larval instar of 3.3 is found in the lab studies and supported by three years of insectary studies. Seven years of black light trapping of ECB moths in Goldsboro, NC, revealed the likelihood of up to four moth flights/year. Information about the diapause biology of this insect is used to explain both the number of flights and the relative magnitude of the final moth flights. On average, the majority of ECB lineages pass through three generations/year with early maturing ECB's producing a significant and predictable fourth generation. The timing and magnitude of the fourth flight can be partly explained on the basis of the critical photophase and the timing and age structure of previous ECB generations. In most years, the fourth flight is smaller than the third due to the majority of the fourth generation's predisposition towards diapause. However, in at least one case (1977), the fourth flight was unusually large and could be predicted by slight temporal shifts in the previous three flights resulting in the majority of the fourth generation larvae averting diapause. The value of the ECB-diapause interaction as a model system for the explanation and prediction of dynamic phenological events is discussed.Type of Medium: Electronic ResourceURL: -
9Articles: DFG German National LicensesStaff View
ISSN: 1570-7458Keywords: intercrop effects ; European corn borer ; Ostrinia nubilalis ; maize ; potatoSource: Springer Online Journal Archives 1860-2000Topics: BiologyNotes: Abstract Field investigations conducted from 1982 to 1984 to assess intercrop effects on the distribution of Ostrinia nubilalis (Hübner), Lepidoptera, Pyralidae, in maize revealed that the incidence of damage by O. nubilalis was influenced significantly by the proximity of maize to potato. Maize fields adjacent to potato fields had a lower incidence of early season damage by O. nubilalis and a higher incidence of late-season damage than maize isolated from potato.Type of Medium: Electronic ResourceURL: -
10Articles: DFG German National LicensesStaff View
ISSN: 1432-0703Source: Springer Online Journal Archives 1860-2000Topics: Energy, Environment Protection, Nuclear Power EngineeringMedicineNotes: Abstract The red blood cell and plasma cholinesterase (ChE) levels of cotton scouts inspecting foliage for insect infestation and damage were monitored. Group means for ChE activity were significantly depressed at one or more time(s) during four of the eight growing seasons studied. Although no symptoms of organophosphate poisoning were confirmed, several scouts exhibited ChE depressions over 50% of pre-exposure levels.Type of Medium: Electronic ResourceURL: -
11Articles: DFG German National LicensesOwers-Bradley, J. R. ; Bowley, R. M. ; Naish, J. H. ; Richardson, P. J. ; Voncken, A. P. J. ; König, R. K.
Springer
Published 1998Staff ViewISSN: 1573-7357Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract In this paper we report measurements of the damping of a vibrating wire in spin polarized liquid helium mixtures. The dilute helium solutions have been cooled by nuclear demagnetisation in high magnetic fields such that the spin polarization for a 0.04% mixture is as high 75%. A PtW alloy vibrating wire has been used to probe the viscosity of the liquid. The increase in viscosity on changing the magnetic field from 3 tesla to 11.5 tesla is a factor 3.5 at the lowest temperatures. The results are compared to theory allowing for both s-wave and p-wave scattering.Type of Medium: Electronic ResourceURL: -
12Articles: DFG German National LicensesCandela, D. ; Akimoto, H. ; Bowley, R. M. ; Buu, O. ; Clubb, D. ; Owers-Bradley, J. R.
Springer
Published 2000Staff ViewISSN: 1573-7357Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract We report new experiments on the transverse and longitudinal spin dynamics of liquid 3 He polarized by an 11.3T field. At the lowest temperatures probed, the transverse spin diffusion coefficient saturates with an apparent anisotropy temperature of Ta=12±2 mK. This temperature dependence is in accord with the general idea of spin-diffusion anisotropy but the value of Ta is half that expected from extrapolating earlier experiments at a lower field. Strong magnetostatic effects in the form of long-lived spin modes are also observed for small gradients and small tipping angles.Type of Medium: Electronic ResourceURL: -
13Articles: DFG German National LicensesChurch, R. J. ; Main, P. C. ; Owers-Bradley, J. R. ; Jones, M. A. ; Bowley, R. M.
Springer
Published 1988Staff ViewISSN: 1573-7357Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract We generate second-sound resonances in a cylindrical cavity in3He-4He mixtures using vibrating Nuclepore filters. The properties of the cavity resonances are well described by the theory proposed by d'Humieres et al. The theory predicts the strength of cavity resonances as well as the phase shift between in- and out-of-phase components of the signal. By fitting these quantities we are able to get information about the compliance of the membrane, the distance of the membrane to the backplate, and the resistance to flow through the membrane. This enables us to predict the reflection coefficient of second-sound waves off the transducer. We also study the effect of a strong magentic field on the resonances.Type of Medium: Electronic ResourceURL: -
14Articles: DFG German National LicensesOwers-Bradley, J. R. ; Main, P. C. ; Bowley, R. M. ; Batey, G. J. ; Church, R. J.
Springer
Published 1988Staff ViewISSN: 1573-7357Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract We measured the specific heat capacity of three dilute mixtures (2.6, 1.07, and 0.44%) of3He in4He and of pure4He. The4He contribution to the specific heat of the mixture is subtracted, leaving only the3He part. This is fitted to a theoretical expression over the whole temperature range from 10 to 700 mK. Assuming a dispersion relation of the form ε=ħ2 k 2(1+γk 2)/2m*, the fits yield the value of γ and the effective mass m* of each mixture. The average value of γ is −0.076±0.01 A2 and the effective mass in the limit of zero concentration is (2.23±0.02)m 3. These are compared to values deduced from other measurements.Type of Medium: Electronic ResourceURL: -
15Articles: DFG German National LicensesOwers-Bradley, J. R. ; Main, P. C. ; Church, R. J. ; Hampson, T. M. M. ; McHale, G. ; Bowley, R. M.
Springer
Published 1989Staff ViewISSN: 1573-7357Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract We have measured the increase in damping of second sound in 0.1% and 0.05%3He-4He solutions upon application of a magnetic field of 10 T. The increase is caused by changes in the thermal conductivity and viscosity of the mixture as the system becomes spin polarized. We show how to fit the data for the viscosity in zero-field to obtain an estimate of the interaction between the3He quasiparticles. It is then possible to predict the viscosity in a field of 10 T using the calculation of Hampson et al. The data agree with the theory to within 2%.Type of Medium: Electronic ResourceURL: -
16Articles: DFG German National LicensesStaff View
ISSN: 1573-7357Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract Multiple spin echoes (MSEs) in3He and in3He-4He mixtures have been analyzed using a theoretical technique proposed by Einzel et al. In both systems MSEs are generated by Fermi liquid interactions, but for3He, MSEs are also generated at higher temperatures by the dipolar demagnetizing field. The theory is compared with the experimental results for3He and with our measurements for3He-4He mixtures. We have improved on the fit to the second echo heights for3He given by Einzel et al. by taking account of both the Leggett-Rice effect and the dipolar interaction in the calculation. Good fits were also found for the first and second echo heights for the3He-4He data. The third echo height is larger than expected if we assume that the total magnetization remains uniform in space. We have developed the theory for the case when this approximation is not made, and we find good agreement for the first five echoes.Type of Medium: Electronic ResourceURL: -
17Articles: DFG German National LicensesOwers-Bradley, J. R. ; Wightman, D. R. ; Child, A. ; Bedford, A. ; Bowley, R. M.
Springer
Published 1992Staff ViewISSN: 1573-7357Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract We report a study of the Leggett-Rice effect in dilute 3He-4He solutions at a Larmor frequency of 71 MHz. We have measured the height and phase of the spin echoes following 2-pulse NMR sequences of three solutions with 3He concentrations of 0.56%, 1.4%, and 4.0%. The theory of Leggett fits the data extremely well and yields values of the parameter ΜM 0 and the transverse diffusion coefficient D. We are also able to evaluate ΜM 0 and D by analyzing multiple spin echoes and find good consistency between the two methods. From values of λ/(1+F 0 a ) at various concentrations, we are able to determine the scattering length for 3He quasiparticles, a, quite accurately. We find a = −0.97±0.03 Å.Type of Medium: Electronic ResourceURL: -
18Articles: DFG German National LicensesStaff View
ISSN: 1573-7357Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract Using pulsed NMR techniques, we have measured spin diffusion in3He-3He solutions with3He concentrations of 0.05%, 0.1%, 0.46%, 1.0%, 3.8% and 6.4% in a magnetic field of 8.8 Tesla for a temperature range 11 mK⩽ T ⩽ 200 mK. We observe that the temperature dependence of the transverse spin diffusion coefficient D1 deviates from that expected for an unpolarized Fermi liquid in the degenerate region in the 1.0%, 3.8% and 6.4% solutions. Moreover, by measuring both longitudinal and transverse spin diffusion coefficients in the 6.4%-mixture, we have verified experimentally the difference between them, and provided direct evidence for a field-induced anisotropy in spin diffusion. The results from the 0.05% and 0.1% solutions show agreement with the theory of Jeon and Mullin; however, no deviation of D1 from that expected in an unpolarized mixture was observed because the3He is not in the degenerate regime for these very dilute systems for the temperatures we could achieve. The analysis of our measurements in terms of the Leggett-Rice equations also yields values for the spin rotation parameter μM0. Using our results along with previous measurements at various3He concentrations, we deduce a value for the s-wave quasiparticle scattering length of a=−0.88 ± 0.05 Å.Type of Medium: Electronic ResourceURL: -
19Articles: DFG German National LicensesStaff View
ISSN: 1573-7357Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract The theory of dilute mixtures of3He in4He that have been polarized by a strong magnetic field is developed. The interaction between the quasiparticles is taken to be constant, an approximation valid at low temperatures. The polarization of the mixture depends on the strength of the interaction. The internal energy, the specific heat, the osmotic pressure, and the velocity of second sound are also calculated. The specific heat is relatively insensitive to the interaction, but it does change significantly with magnetic field. The osmotic pressure is more sensitive to the effects of the interaction for some3He concentrations and temperatures. The velocity of second sound behaves qualitatively like the osmotic pressure. The measurement of these quantities as a function of temperature and magnetic field is discussed with a view to obtaining the strength of the interaction between quasiparticles.Type of Medium: Electronic ResourceURL: -
20Articles: DFG German National LicensesStaff View
ISSN: 1573-7357Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract Spin waves have been reported previously in3He-4He mixtures using cw-NMR. The spin waves form standing waves in the rf coil used to detect the NMR signal. Only one resonance was observed, corresponding to ak vector of 1 mm−1. This is in sharp contrast to similar experiments performed on pure3He, where several resonances were seen. An explanation is given of why this occurs and the resonant mode is identified. Furthermore, it is explained why there is an extra width to the resonance for temperatures below 2 mK. This is caused by radiation damping of the resonant mode. The theory is found to be in excellent agreement with the data. Further experiments are suggested, including details of an improved rf coil design, which should lead to information about the quasiparticle interaction.Type of Medium: Electronic ResourceURL: