659 research outputs found
Characteristics of ferroelectric-ferroelastic domains in N{\'e}el-type skyrmion host GaVS
GaVS is a multiferroic semiconductor hosting N{\'e}el-type magnetic
skyrmions dressed with electric polarization. At T = 42K, the compound
undergoes a structural phase transition of weakly first-order, from a
non-centrosymmetric cubic phase at high temperatures to a polar rhombohedral
structure at low temperatures. Below T, ferroelectric domains are formed
with the electric polarization pointing along any of the four axes. Although in this material the size and the shape of the
ferroelectric-ferroelastic domains may act as important limiting factors in the
formation of the N{\'e}el-type skyrmion lattice emerging below T=13\:K, the
characteristics of polar domains in GaVS have not been studied yet.
Here, we report on the inspection of the local-scale ferroelectric domain
distribution in rhombohedral GaVS using low-temperature piezoresponse
force microscopy. We observed mechanically and electrically compatible lamellar
domain patterns, where the lamellae are aligned parallel to the (100)-type
planes with a typical spacing between 100 nm-1.2 m. We expect that the
control of ferroelectric domain size in polar skyrmion hosts can be exploited
for the spatial confinement and manupulation of N{\'e}el-type skyrmions
Thermal modelling of a porous silicon-based pellistor-type catalytic flammable gas sensor with two supporting beams
A three-dimensional transient thermal mathematical model of a porous silicon based pellistor with two supporting beams was developed. The model was numerically solved using the implicit alternating-direction finite difference method. A computer program written in ANSI C and run on a VAX/VMS computer was utilized to study the influence of the power consumption and the main geometrical dimensions (membrane, beam and heater size) of the pellistor mentioned above on its transient and steady-state thermal behaviour. It was found that considerable improvement in the thermal behaviour of the pellistor could be achieved by reducing the membrane size (length and width). The optimal beam length was determined as 100 μm. By comparing the main sources of energy dissipation it was found that energy was lost predominantly through the heat conduction into the supporting beams
A Mohács előtti levéltári források automatizált információs rendszere III. = Computer aided data processing of medieval documents in the national archives of Hungary
A Magyar Országos Levéltár (MOL) DL-DF adatbázisa az 1526 aug. 29. előtt keletkezett levéltári forrásanyag nyilvántartása: mintegy 300000 dokumentum alapadatai (dátum, kibocsátó, jelzetek, fennmaradási forma) mellett mintegy 75000 tartalmi kivonatot, az alapvető forráskiadványok szövegeit, 15000 oklevél képét, 100000 papíralapú segédlet képeit is tartalmazza. A pályázat az adatbázis továbbfejlesztését célozta. Elérhető a MOL kutatótermében belső hálózatról, oklevélképek nélküli változata DVD-n is megjelent. Mindenfajta középkorra irányuló kutatás alapvető és megkerülhetetlen segédeszköze. | The medieval database of State Archives of Hungary contains registers of archival sources issued before 29th August 1526 (day of Battle of Mohács, so called 'Mohács disaster'). Present application is aimed to improve the database, which provides the most important data of 300000 documents (such as issuer of the document, date, reference number, survival form), furthermore 75000 excerpts of content, texts of essential publications of charters, pictures of 15000 documents, digital pictures of all excerpts (100000). The database is available in the research room of the National Archives and is published as a DVD-Rom (in 2008), without including pictures. The database is indispensable aid of every medieval research
Physical Activity, Sedentary Behavior, and Long-Term Changes in Aortic Stiffness: The Whitehall II Study
BACKGROUND: Physical activity is associated with reduced cardiovascular disease risk, mainly through effects on atherosclerosis. Aortic stiffness may be an alternative mechanism. We examined whether patterns of physical activity and sedentary behavior are associated with rate of aortic stiffening. METHODS AND RESULTS: Carotid-femoral pulse wave velocity (PWV) was measured twice using applanation tonometry at mean ages 65 (in 2008/2009) and 70 (in 2012/2013) years in the Whitehall-II study (N=5196). Physical activity was self-reported at PWV baseline (2008/2009) and twice before (in 1997/1999 and 2002/2003). Sedentary time was defined as sitting time watching television or at work/commute. Linear mixed models adjusted for metabolic and lifestyle risk factors were used to analyze PWV change. Mean (SD) PWV (m/s) was 8.4 (2.4) at baseline and 9.2 (2.7) at follow-up, representing a 5-year increase of 0.76 m/s (95% CI 0.69, 0.83). A smaller 5-year increase in PWV was observed for each additional hour/week spent in sports activity (-0.02 m/s [95% CI -0.03, -0.001]) or cycling (-0.02 m/s [-0.03, -0.008]). Walking, housework, gardening, or do-it-yourself activities were not significantly associated with aortic stiffening. Each additional hour/week spent sitting was associated with faster PWV progression in models adjusted for physical activity (0.007 m/s [95% CI 0.001, 0.013]). Increasing physical activity over time was associated with a smaller subsequent increase in PWV (-0.16 m/s [-0.32, -0.002]) compared with not changing activity levels. CONCLUSIONS: Higher levels of moderate-to-vigorous physical activity and avoidance of sedentary behavior were each associated with a slower age-related progression of aortic stiffness independent of conventional vascular risk factors
Modest genetic influence on bronchodilator response: a study in healthy twins.
AIM: To determine the reasons for large standard deviation of bronchodilator response (BDR) and establish whether there is a potential heritable component in healthy subjects. METHODS: 67 monozygotic and 42 dizygotic adult twin pairs were assessed for bronchodilator response (% change in FEV1 after inhaling 400 microg salbutamol). Univariate quantitative genetic modeling was performed. RESULTS: Multiple regression modeling showed a significant association between BDR and sex and baseline FEV1 (P<0.05), while no association was found with smoking habits, body mass index, or age. Within pair correlation in monozygotic twins was modest (0.332), but higher than in dizygotic twins (0.258). Age-, sex-, and baseline FEV1-adjusted genetic effect accounted for 14.9% (95% confidence interval, CI 0%-53.1%) of the variance of BDR, shared environmental effect for 18.4% (95% CI 0%-46.8%), and unshared environmental effect for 66.8% (95% CI 46.8%-88.7%). CONCLUSION: Our twin study showed that individual differences in BDR can be mostly explained by unshared environmental effects. In addition, it is the first study to show low, insignificant hereditary influences, independently from sex, age, and baseline FEV1
Photon Rates for Heavy-Ion Collisions from Hidden Local Symmetry
We study photon production from the hidden local symmetry approach that
includes pions, rho and a1 mesons and compute the corresponding photon emission
rates from a hadronic gas in thermal equilibrium. Together with experimental
radiative decay widths of the background, these rates are used in a
relativistic transport model to calculate single photon spectra in heavy-ion
collisions at SPS energies. We then employ this effective theory to test three
scenarios for the chiral phase transition in high-temperature nuclear matter
including decreasing vector meson masses. Although all calculations respect the
upper bound set by the WA80 Collaboration, we find the scenarios could be
distinguished with more detailed data.Comment: 12 pages, 12 Postscript figures; discussion of thermal equilibrium
rates expanded, minor corrections to text and graph
The white collar complex is essential for sexual reproduction but dispensable for conidiation and invasive growth in Fusarium verticillioides
Fvwc1 and Fvwc2, orthologues of the wc-1 and wc-2 genes encoding for proteins of the white collar complex (WCC) in Neurospora crassa were cloned from Fusarium verticillioides and lack-of-function wc mutants were obtained by targeted gene disruption. Photo-conidiation was found to be absent in F. verticillioides, on the contrary, the wild type strain produced less conidia under continuous illumination than in the dark. Inactivation of any of the wc genes led to total female sterility, without affecting male fertility or asexual conidiation. No loss in colonization capability/invasive growth of the wc mutants was observed, when assessed on tomato fruits. Both Fvwc1 and Fvwc2 showed constitutive expression in the wild type cultures incubated in the dark and exposure to light caused only negligible increases in their transcription. Both Fvwc1 and Fvwc2 were down-regulated in a ΔFvmat1-2-1 gene disruption mutant, lacking a functional mating type (mat1-2-1) gene, suggesting that the MAT1-2-1 product has a positive regulatory effect on the white collar genes
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