2,444 research outputs found
New results for virial coefficients of hard spheres in D dimensions
We present new results for the virial coefficients B_k with k <= 10 for hard
spheres in dimensions D=2,...,8.Comment: 10 pages, 5 figures, to appear in conference proceedings of STATPHYS
2004 in Pramana - Journal of Physic
Opportunities for Dutch Biorefineries
Deze Roadmap Bioraffinage beschrijft een aantal mogelijke routes naar de ontwikkeling en implementatie van een bioraffinage-gerelateerde Bio-based Economy in Nederland. De Roadmap combineert korte- en middellange termijn mogelijkheden (commerciële implementatie, demonstratie plants, pilot plants en gerelateerd toegepast onderzoek) met strategisch onderzoek voor de langere termijn. Tevens zijn vier z.g. Moonshots uitgewerkt, als voorziene bioraffinagestrategieën met een grote potentie voor de Nederlandse economi
Chaotic ray dynamics in an optical cavity with a beam splitter
We investigate the ray dynamics in an optical cavity when a ray splitting
mechanism is present. The cavity is a conventional two-mirror stable resonator
and the ray splitting is achieved by inserting an optical beam splitter
perpendicular to the cavity axis. Using Hamiltonian optics, we show that such a
simple device presents a surprisingly rich chaotic ray dynamics.Comment: 6 pages, 4 figure
Molecular and immunological characterization of profilin from mugwort pollen
In late summer in Europe, pollen of mugwort is one of the major sources of atopic allergens. No information about the complete molecular structure of any mugwort allergen has been published so far. Here we report the isolation and characterization of mugwort pollen cDNA clones coding for two isoforms of the panallergen profilin. Thirtysix percent of the mugwort allergic patients tested displayed IgE antibodies against natural and recombinant profilin, and no significant differences were observed in the IgEbinding properties of the isoforms. One profilin isoform was purified to homogeneity and detailed structural analysis indicated that the protein exists in solution as dimers and tetramers stabilized by sulfydryl and/or ionic interactions. Profilin monomers were detectable only after exposure of multimers to harsh denaturing conditions. Dimers and tetramers did not significantly differ in their ability to bind serum IgE from mugwort pollenallergic patients. However, oligomeric forms might have a higher allergenic potential than monomers because larger molecules would have additional epitopes for IgEmediated histamine release. Profilin isolated from mugwort pollen also formed multimers. Thus, oligomerization is not an artifact resulting from the recombinant production of the allergen. Inhibition experiments showed extensive IgE crossreactivity of recombinant mugwort profilin and profilin from various pollen and food extracts
Scattering properties of a cut-circle billiard waveguide with two conical leads
We examine a two-dimensional electron waveguide with a cut-circle cavity and
conical leads. By considering Wigner delay times and the Landauer-B\"{u}ttiker
conductance for this system, we probe the effects of the closed billiard energy
spectrum on scattering properties in the limit of weakly coupled leads. We
investigate how lead placement and cavity shape affect these conductance and
time delay spectra of the waveguide.Comment: 18 pages, 11 figures, accepted for publication in Phys. Rev. E (Jan.
2001
Universal low-temperature behavior of frustrated quantum antiferromagnets in the vicinity of the saturation field
We study the low-temperature thermodynamic properties of a number of
frustrated quantum antiferromagnets which support localized magnon states in
the vicinity of the saturation field. For this purpose we use 1) a mapping of
the low-energy degrees of freedom of spin systems onto the hard-core object
lattice gases and 2) an exact diagonalization of finite spin systems of up to
N=30 sites. The considered spin systems exhibit universal behavior which is
determined by a specific hard-core object lattice gas representing the
independent localized magnon states. We test the lattice gas description by
comparing its predictions with the numerical results for low-lying energy
states of finite spin systems. For all frustrated spin systems considered we
find a strong variation of the low-temperature specific heat passing the
saturation field and a maximum in the isothermal entropy at saturation field
resulting in an enhanced magnetocaloric effect.Comment: 21 pages, 8 figure
Properties of planetary fluids at high pressure and temperature
In order to derive models of the interiors of Uranus, Neptune, Jupiter and Saturn, researchers studied equations of state and electrical conductivities of molecules at high dynamic pressures and temperatures. Results are given for shock temperature measurements of N2 and CH4. Temperature data allowed demonstration of shock induced cooling in the the transition region and the existence of crossing isotherms in P-V space
BEGIN Partnership: Using Problem-Based Learning to Teach Genetics & Bioethics
A science education center at a university medical school had grant funding to develop a genetics curriculum unit, but needed a dissemination plan. A statewide science teacher organization that provided professional development training was facing decreased funding. These two groups combined their efforts, and created a unique partnership, called BEGIN (Biotechnology, Ethics and Genetics Instructional Network) that has brought together university medical and science faculty and high school biology teachers. The main goal of this partnership is to provide high school biology teachers with new instructional tools to face the challenges of teaching genetics and bioethics in a manner that is content-rich, research and standards-based, and relevant to students\u27 lives. This article describes the BEGIN partnership and summarizes the tiered approach used for designing, pilot-testing, and disseminating a new problem-based learning (PBL) curriculum module on the bioethics of DNA testing for Huntington\u27s disease. The article also provides some preliminary data on the effectiveness of this approach in transforming teacher practice
Ninth and Tenth Order Virial Coefficients for Hard Spheres in D Dimensions
We evaluate the virial coefficients B_k for k<=10 for hard spheres in
dimensions D=2,...,8. Virial coefficients with k even are found to be negative
when D>=5. This provides strong evidence that the leading singularity for the
virial series lies away from the positive real axis when D>=5. Further analysis
provides evidence that negative virial coefficients will be seen for some k>10
for D=4, and there is a distinct possibility that negative virial coefficients
will also eventually occur for D=3.Comment: 33 pages, 12 figure
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