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Wyświetlanie 1-3 z 3
Tytuł:
Skyrmions and the ν=1 Quantum Hall Ferromagnet
Autorzy:
Manfra, M. J.
Goldberg, B. B.
Pfeiffer, L.
West, K.
Powiązania:
https://bibliotekanauki.pl/articles/1967963.pdf
Data publikacji:
1997-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Hm
78.66.-w
73.20.Mf
71.70.Gm
73.20.Dx
Opis:
Recent experimental and theoretical investigations have resulted in a shift in our understanding of the ν=1 quantum Hall state. There now exists a wealth of evidence that the excitation gap and the resulting quasiparticle spectrum at ν=1 are due predominately to the ferromagnetic many-body exchange interaction. A great variety of experimentally observed correlations at ν= 1 cannot be incorporated into a perturbative expansion around the single-particle model, a scheme long thought to describe the integral quantum Hall effect at filling factor 1. Theorists now refer to the ν=1 state as the quantum Hall ferromagnet. In this paper we review recent theoretical and experimental progress and detail our own optical investigations of the ν= 1 quantum Hall regime. The technique of magneto-absorption spectroscopy has proven to be powerful a probe of the occupancy of the lowest Landau level in the regime of 0.7<ν<1.3 about the spin gap. Additionally, we have performed simultaneous measurements of the absorption, photoluminescence and photoluminescence excitation spectra of the ν=1 state in order to elucidate the role of excitonic and relaxation effects in optical spectroscopy in the quantum Hall regime.
Źródło:
Acta Physica Polonica A; 1997, 92, 4; 621-632
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tobacco smoking in countries of the European Union
Autorzy:
Zatonski, W.
Przewozniak, K.
Sulkowska, U.
West, R.
Wojtyla, A.
Powiązania:
https://bibliotekanauki.pl/articles/49377.pdf
Data publikacji:
2012
Wydawca:
Instytut Medycyny Wsi
Opis:
Background: Existing smoking prevalence comparisons between the ‘old’ and ‘new’ members of the European Union (EU) give a misleading picture because of differences in methodology. A major EU project designed to find ways of closing the health gap between the member states, included the first ever comparison of smoking prevalence between these countries using a methodology that minimises potential biases. Methods: A detailed analysis of methods and data from the most recent nationwide studies was conducted in the adult population of 27 countries of the European Union and Russia as an external comparator. To maximise comparability, daily smoking in the age range 20-64 was used. Prevalence of current daily smoking, former smoking and never smoking were age-standardised and calculated separately for males and females. Findings: The European map of smoking prevalence shows that male smoking prevalence is much higher in the new than the old members of the EU, whereas in females the reverse is true, but there are also very large differences in smoking rates between particular countries within the same region. Sweden clearly has the lowest prevalence, and the prevalence in the United Kingdom (UK) at the time of the surveys emerges as near the average for old-Europe but higher than, for example, Ireland. Interpretation: Restricting the analysis to daily smokers aged 20-64 produces a map of Europe in which variation in prevalence between individual countries within regions is as important as variation across regions. Survey methods need to be harmonised across countries to enable comparisons involving all ages and non-daily as well as daily smokers.
Źródło:
Annals of Agricultural and Environmental Medicine; 2012, 19, 2
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Xylem-fed maple sap accelerates balsam fir needle abscission and but can delay water loss in spring and autumn
Autorzy:
MacDonald, M.T.
Lada, R.R.
West, R.R.
Nelson, K.L.
Powiązania:
https://bibliotekanauki.pl/articles/40990.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
xylem
abscisic acid
Abies balsamea
balsam
fir tree
balsam fir tree
needle
water content
water uptake
water loss
spring
autumn
Opis:
Postharvest balsam fir trees are known to suffer a number of problems that may be linked to abscission rates, such as dehydration or wounding. By definition, postharvest balsam fir trees are also detached from roots and will no longer be supplied certain root derived factors normally translocated via the xylem. Resupplying those root derived factors may delay abscission. The objective of this experiment was to take sap from a root intact species (i.e. Acer saccharum L) and add it to the water supply of balsam fir branches. Further, the effect of reverse osmosis and autoclaving the sap supply will be explored. The experiment was conducted once in spring and again in autumn to examine seasonal changes in needle abscission. The only hormones found in the maple sap were ABA and its metabolites, with PA (163.0 ng g–1) being the primary metabolite present. Needle retention was higher in branches harvested in autumn, as long as they were provided a sap that did not undergo RO. If the sap had undergone RO, then needle retention was slightly decreased in autumn. Needle retention generally decreased as the concentration of maple sap in the water supply increased and this trend was accelerated if the sap had undergone RO. Autoclaving the sap successfully delayed the length of time for water consumption to decrease, but this unexpectedly did not translate into improved needle retention.
Źródło:
Dendrobiology; 2016, 76
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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