Neu- und Wiederfunde des Reinweißen Hahnenfußes (Ranunculus ololeucos) in Niedersachsen und Nordrhein-Westfalen

In den Jahren 1986 bis 1990 wurde Ranunculus ololeucos (Reinweißer Hahnenfuß) im nordwestlichen Westfalen und südöstlichen Niedersachsen an 17 Gewässern beobachtet. Einen Verbreitungsschwerpunkt bildet der Naturraum "Gildehauser Venn". Ursache für viele Neu- und Wiederfunde dürfte der für Ranunculus ololeucos günstige Witterungsverlauf der letzten Jahre mit mehreren trockenen Sommerhalbjahren gewesen sein. Noch stärker als durch Eutrophierung erscheint die Art wie auch andere Littorelletea-Arten durch die zunehmende Versauerung der nährstoffarmen Stillgewässer gefährdet

Vacuum stress-energy density and its gravitational implications

In nongravitational physics the local density of energy is often regarded as merely a bookkeeping device; only total energy has an experimental meaning - and it is only modulo a constant term. But in general relativity the local stress-energy tensor is the source term in Einstein\u27s equation. In closed universes, and those with Kaluza-Klein dimensions, theoretical consistency demands that quantum vacuum energy should exist and have gravitational effects, although there are no boundary materials giving rise to that energy by van der Waals interactions. In the lab there are boundaries, and in general the energy density has a nonintegrable singularity as a boundary is approached (for idealized boundary conditions). As pointed out long ago by Candelas and Deutsch, in this situation there is doubt about the viability of the semiclassical Einstein equation. Our goal is to show that the divergences in the linearized Einstein equation can be renormalized to yield a plausible approximation to the finite theory that presumably exists for realistic boundary conditions. For a scalar field with Dirichlet or Neumann boundary conditions inside a rectangular parallelepiped, we have calculated by the method of images all components of the stress tensor, for all values of the conformal coupling parameter and an exponential ultraviolet cutoff parameter. The qualitative features of contributions from various classes of closed classical paths are noted. Then the Estrada-Kanwal distributional theory of asymptotics, particularly the moment expansion, is used to show that the linearized Einstein equation with the stress-energy near a plane boundary as source converges to a consistent theory when the cutoff is removed. © 2008 IOP Publishing Ltd

Strange vector form factors of the nucleon in the SU(3) chiral quark-soliton model with the proper kaonic cloud

The strange vector form factors are evaluated in the range between $Q^2=0$ and Q^2=1\ \mbox{GeV}^2 in the framework of the SU(3) chiral quark-soliton model (or semi-bosonized SU(3) Nambu-Jona-Lasinio model). The rotational $1/N_c$ and $m_s$ corrections are taken into account up to linear order. Taking care of a proper Yukawa-tail of the kaonic cloud, we get \langle r^{2}\rangle^{\rm Sachs}_{s}=-0.095\; \mbox{fm}^2 and $\mu_s = -0.68\;\mu_N$. The results are compared with several different models.Comment: 27 pages with 8 figures. RevTeX and epsfig.sty are used. Submitted to Nucl. Phys.

Basic fibroblast growth factor (bFGF) in rodent testis

We have previously described a 30 kDa basic fibroblast growth factor (bFGF)-like protein in rodent testicular homogenates and have shown that pachytene spermatocytes are the sites of predominant immunoreactivity for this bFGF-like protein (Mayerhofer, A., Russell, L.D., Grothe, C., Rudolf, M. and Gratzl, M. (1991) Endocrinology 129, 921–924). We have now addressed the question whether this 30 kDa bFGF-like protein is a large bFGF form and whether it is produced by pachytene spermatocytes. We detected bFGF mRNA in homogenates of isolated mouse spermatocytes (which consisted mainly of pachytene spermatocytes) using S1 nuclease protection assays. As shown by Western blot analyses, the bFGF mRNA in mouse spermatocytes is translated into bFGF of an approximate molecular weight of 30 kDa. Neither bFGF mRNA, nor bFGF itself, was observed in isolated mouse Leydig cells. These results indicate that the immunoreactive bFGF-like protein observed previously in germ cells of the murine testis is identical to bFGF. Thus, germ cells of the testis produce bFGF, which may exert regulatory function in the process of spermatogenesis

Measuring antimatter gravity with muonium

The gravitational acceleration of antimatter, ḡ, has never been directly measured and could bear importantly on our understanding of gravity, the possible existence of a fifth force, and the nature and early history of the universe. Only two avenues for such a measurement appear to be feasible: antihydrogen and muonium. The muonium measurement requires a novel, monoenergetic, low-velocity, horizontal muonium beam directed at an atom interferometer. The precision three-grating interferometer can be produced in silicon nitride or ultrananocrystalline diamond using state-of-the-art nanofabrication. The required precision alignment and calibration at the picometer level also appear to be feasible. With 100 nm grating pitch, a 10% measurement of ḡ can be made using some months of surface-muon beam time, and a 1% or better measurement with a correspondingly larger exposure. This could constitute the first gravitational measurement of leptonic matter, of 2nd-generation matter and, possibly, the first measurement of the gravitational acceleration of antimatter

Conditional Allocation of Control Rights in Venture Capital Finance

When a young entrepreneurial firm matures, it is often necessary to replace the founding entrepreneur by a professional manager. This replacement decision can be affected by the private benefits of control enjoyed by the entrepreneur which gives rise to a conflict of interest between the entrepreneur and the venture capitalist. We show that a combination of convertible securities and contingent control rights can be used to resolve this conflict efficiently. This contractual arrangement is frequently observed in venture capital finance