Subdivision Directional Fields

We present a novel linear subdivision scheme for face-based tangent directional fields on triangle meshes. Our subdivision scheme is based on a novel coordinate-free representation of directional fields as halfedge-based scalar quantities, bridging the finite-element representation with discrete exterior calculus. By commuting with differential operators, our subdivision is structure-preserving: it reproduces curl-free fields precisely, and reproduces divergence-free fields in the weak sense. Moreover, our subdivision scheme directly extends to directional fields with several vectors per face by working on the branched covering space. Finally, we demonstrate how our scheme can be applied to directional-field design, advection, and robust earth mover's distance computation, for efficient and robust computation

Evaluatie Pilot Natuursprong

In april 2008 is het startsein gegeven voor Natuursprong. een bewegings- en spelprogramma in de natuur dat bedoeld is om kinderen uit steden meer buiten te laten bewegen, om zo een betere gezondheid te garanderen. Dit project wordt gedragen door drie organisaties: Staatsbosbeheer, Nederlands Instituut voor Sport en Beweging (NISB) en Jantje Beton. Natuursprong is een bewegings- en spelprogramma dat speciaal voor dit project door het NISB is ontwikkeld en wordt uitgevoerd in natuurgebieden van Staatsbosbeheer. In september en oktober 2008 zijn er in Nijmegen en Breda pilotprogramma’s aangeboden. Deze zijn nu op verzoek van Staatsbosbeheer geëvalueerd. De voorliggende notitie geeft een inhoudelijke evaluatie van de pilo

Quasiparticles near quantum phase transition in heavy fermion metals

We have shown that the Landau paradigm based upon both the quasiparticle concept and the notion of the order parameter can be used to explain the anomalous behavior of heavy fermion metals. Exploiting this paradigm and the fermion condensation quantum phase transition (FCQPT) we show that this anomalous behavior is universal and can be used to capture the essential aspects of recent experiments on the heavy-fermion metals at low temperatures. Behind FCQPT a tunneling conductivity between a heavy fermion metal and a simple metallic point can be noticeably dissymmetrical with respect to the change of voltage bias. We show that at T=0 and beyond FCQPT the Hall coefficient undergoes a jump upon magnetic-field tuning HF metals.Comment: 2 pages, 1 figure, submitted to the SCES'0

Ferromagnetic quantum critical fluctuations in YbRh_2(Si_{0.95}Ge_{0.05})_2

The bulk magnetic susceptibility $\chi(T,B)$ of YbRh$_2$(Si$_{0.95}$Ge$_{0.05}$)$_2$ has been investigated %by ac-and dc-magnetometry at low temperatures and close to the field-induced quantum critical point at $B_c=0.027$ T. For $B\leq 0.05$ T a Curie-Weiss law with a negative Weiss temperature is observed at temperatures below 0.3 K. Outside this region, the susceptibility indicates ferromagnetic quantum critical fluctuations: $\chi(T)\propto T^{-0.6}$ above 0.3 K, while at low temperatures the Pauli susceptibility follows $\chi_0\propto (B-B_c)^{-0.6}$ and scales with the coefficient of the $T^2$ term in the electrical resistivity. The Sommerfeld-Wilson ratio is highly enhanced and increases up to 30 close to the critical field.Comment: Physical Review Letters, to be publishe

Quadrupolar interactions in heavy fermion metal YbRh2Si2

We describe the experimentally revealed by Sichelschmidt et al, Phys. Rev. Lett. 91 (2003) 156401, g tensor, g_perpendicular=3.561 and g_parallel=0.17, at 5 K by means of crystal field interactions of the 4f13 configuration of the Yb3+ ion of YbRh2Si2 in a slightly orthorhombically distorted tetragonal crystal field. We have shown that the temperature dependence of the quadrupolar interactions Q(T) of the Yb nucleous will help to distinguish between Gamma_7 and Gamma_6 ground state. For the Gamma_7 ground state Q(T) is expected to exhibits an anomalous dependence. Keywords: heavy fermion, crystal field, quadrupolar moment,YbRh2Si2Comment: 2 pages LaTeX(Elsevier Science class), 1 figur

Plantlet formation from internode bases of carnation (Dianthus caryophyllus L.) in vivo - useful to mutation breeding or not?

After decapitation of the main shoot and subsequently the axillary shoots of carnation plants, annular zones extending between axils of opposite leaves produced numerous buds. Low temperatures (10-14 deg C) were essential for this bud formation, which was restricted to young internodes. The season affected the time till bud formation, and determined whether the buds were formed from the main axis or the laterals. Indications were found that these buds were adventitious. The possibility of using these buds in mutation breeding, and the possible risks if they are formed during clonal micropropagation in vitro, are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission