254 research outputs found
Domain wall roughening in dipolar films in the presence of disorder
We derive a low-energy Hamiltonian for the elastic energy of a N\'eel domain
wall in a thin film with in-plane magnetization, where we consider the
contribution of the long-range dipolar interaction beyond the quadratic
approximation. We show that such a Hamiltonian is analogous to the Hamiltonian
of a one-dimensional polaron in an external random potential. We use a replica
variational method to compute the roughening exponent of the domain wall for
the case of two-dimensional dipolar interactions.Comment: REVTEX, 35 pages, 2 figures. The text suffered minor changes and
references 1,2 and 12 were added to conform with the referee's repor
The institutional shaping of management: in the tracks of English individualism
Globalisation raises important questions about the shaping of economic action by cultural factors. This article explores the formation of what is seen by some as a prime influence on the formation of British management: individualism. Drawing on a range of historical sources, it argues for a comparative approach. In this case, the primary comparison drawn is between England and Scotland. The contention is that there is a systemic approach to authority in Scotland that can be contrasted to a personal approach in England. An examination of the careers of a number of Scottish pioneers of management suggests the roots of this systemic approach in practices of church governance. Ultimately this systemic approach was to take a secondary role to the personal approach engendered by institutions like the universities of Oxford and Cambridge, but it found more success in the different institutional context of the USA. The complexities of dealing with historical evidence are stressed, as is the value of taking a comparative approach. In this case this indicates a need to take religious practice as seriously as religious belief as a source of transferable practice. The article suggests that management should not be seen as a simple response to economic imperatives, but as shaped by the social and cultural context from which it emerges
Proteomic and transcriptomic changes in hibernating grizzly bears reveal metabolic and signaling pathways that protect against muscle atrophy
Muscle atrophy is a physiological response to disuse and malnutrition, but hibernating bears are largely resistant to this phenomenon. Unlike other mammals, they efficiently reabsorb amino acids from urine, periodically activate muscle contraction, and their adipocytes differentially responds to insulin. The contribution of myocytes to the reduced atrophy remains largely unknown. Here we show how metabolism and atrophy signaling are regulated in skeletal muscle of hibernating grizzly bear. Metabolic modeling of proteomic changes suggests an autonomous increase of non-essential amino acids (NEAA) in muscle and treatment of differentiated myoblasts with NEAA is sufficient to induce hypertrophy. Our comparison of gene expression in hibernation versus muscle atrophy identified several genes differentially regulated during hibernation, including Pdk4 and Serpinf1. Their trophic effects extend to myoblasts from non-hibernating species (including C. elegans), as documented by a knockdown approach. Together, these changes reflect evolutionary favored adaptations that, once translated to the clinics, could help improve atrophy treatment
Volumes of polytopes in spaces of constant curvature
We overview the volume calculations for polyhedra in Euclidean, spherical and
hyperbolic spaces. We prove the Sforza formula for the volume of an arbitrary
tetrahedron in and . We also present some results, which provide a
solution for Seidel problem on the volume of non-Euclidean tetrahedron.
Finally, we consider a convex hyperbolic quadrilateral inscribed in a circle,
horocycle or one branch of equidistant curve. This is a natural hyperbolic
analog of the cyclic quadrilateral in the Euclidean plane. We find a few
versions of the Brahmagupta formula for the area of such quadrilateral. We also
present a formula for the area of a hyperbolic trapezoid.Comment: 22 pages, 9 figures, 58 reference
Parameters of the Magnetic Flux inside Coronal Holes
Parameters of magnetic flux distribution inside low-latitude coronal holes
(CHs) were analyzed. A statistical study of 44 CHs based on Solar and
Heliospheric Observatory (SOHO)/MDI full disk magnetograms and SOHO/EIT 284\AA
images showed that the density of the net magnetic flux, , does
not correlate with the associated solar wind speeds, . Both the area and
net flux of CHs correlate with the solar wind speed and the corresponding
spatial Pearson correlation coefficients are 0.75 and 0.71, respectively. A
possible explanation for the low correlation between and
is proposed. The observed non-correlation might be rooted in the structural
complexity of the magnetic field. As a measure of complexity of the magnetic
field, the filling factor, , was calculated as a function of spatial
scales. In CHs, was found to be nearly constant at scales above 2 Mm,
which indicates a monofractal structural organization and smooth temporal
evolution. The magnitude of the filling factor is 0.04 from the Hinode SOT/SP
data and 0.07 from the MDI/HR data. The Hinode data show that at scales smaller
than 2 Mm, the filling factor decreases rapidly, which means a mutlifractal
structure and highly intermittent, burst-like energy release regime. The
absence of necessary complexity in CH magnetic fields at scales above 2 Mm
seems to be the most plausible reason why the net magnetic flux density does
not seem to be related to the solar wind speed: the energy release dynamics,
needed for solar wind acceleration, appears to occur at small scales below 1
Mm.Comment: 6 figures, approximately 23 pages. Accepted in Solar Physic
Generation of defects and disorder from deeply quenching a liquid to form a solid
We show how deeply quenching a liquid to temperatures where it is linearly
unstable and the crystal is the equilibrium phase often produces crystalline
structures with defects and disorder. As the solid phase advances into the
liquid phase, the modulations in the density distribution created behind the
advancing solidification front do not necessarily have a wavelength that is the
same as the equilibrium crystal lattice spacing. This is because in a deep
enough quench the front propagation is governed by linear processes, but the
crystal lattice spacing is determined by nonlinear terms. The wavelength
mismatch can result in significant disorder behind the front that may or may
not persist in the latter stage dynamics. We support these observations by
presenting results from dynamical density functional theory calculations for
simple one- and two-component two-dimensional systems of soft core particles.Comment: 25 pages, 11 figure
Trunk fat and leg fat have independent and opposite associations with fasting and postload glucose levels: the Hoorn study
Trunk fat and leg fat have independent and opposite associations with fasting and postload glucose levels: the Hoorn study. Snijder MB, Dekker JM, Visser M, Bouter LM, Stehouwer CD, Yudkin JS, Heine RJ, Nijpels G, Seidell JC; Hoorn study. Institute for Research in Extramural Medicine, VU University Medical Center, Amsterdam, The Netherlands. [email protected] OBJECTIVE: Waist and hip circumferences have been shown to have independent and opposite associations with glucose levels. Waist circumference is positively associated with glucose levels, whereas hip circumference is negatively associated. It is unclear which tissues are involved in the pathophysiological mechanism causing these associations. The main goal was to determine which tissue in the trunk and legs, fat or lean tissue, is associated with measures of glucose metabolism. RESEARCH DESIGN AND METHODS: In 623 participants of the third examination of the Hoorn Study, whole-body dual-energy X-ray absorptiometry was performed to determine fat and lean soft-tissue mass in the trunk and legs. Fasting and 2-h postload glucose levels after 75-g oral glucose tolerance test (OGTT) were determined. After exclusion of known diabetic patients, cross-sectional analyses were performed in 275 men aged 60-87 years (140 with normal glucose metabolism, 92 with impaired glucose metabolism; and 43 with diabetes) and in 281 women (148 with normal glucose metabolism, 90 with impaired glucose metabolism, and 43 with diabetes). RESULTS: Greater trunk fat mass was associated with higher glucose levels after adjustment for age, trunk lean mass, leg lean mass, and leg fat mass. Standardized beta (95% CI) in men were 0.44 (0.25-0.64) for fasting and 0.41 (0.22-0.60) for postload glucose. For women, these values were 0.49 (0.35-0.63) and 0.47 (0.33-0.61), respectively. In contrast, in the same regression models, a larger leg fat mass was associated with lower glucose levels. Standardized beta in men were -0.24 (-0.43 to -0.05) and -0.12 (-0.31 to 0.07) and in women -0.24 (-0.37 to -0.10) and -0.27 (-0.40 to -0.13) for fasting and postload glucose, respectively. In these models, larger leg lean mass was also associated with lower glucose levels but was only statistically significant in men. CONCLUSIONS: If trunk fat is taken into account, accumulation of fat in the legs seems to be protective against a disturbed glucose metabolism, particularly in women. Further research is needed to unravel underlying pathophysiological mechanism
Could Fidicina mannifera (Hemiptera: Cicadoidea: Fidicinini) promote a resource pulse in two Brazilian Cerrado vegetation classes?
Fatores limitantes ao crescimento do capim-TanzĂąnia em um sistema agrossilvipastoril com eucalipto, na regiĂŁo dos Cerrados de Minas Gerais
- âŠ