Existence of Multistring Solutions of the Self-Gravitating Massive W−W-Boson

We consider a semilinear elliptic system which include the model system of the $W-$strings in the cosmology as a special case. We prove existence of multi-string solutions and obtain precise asymptotic decay estimates near infinity for the solutions. As a special case of this result we solve an open problem posed in \cite{yan}Comment: 12 page

The Nuclease Activity of the Yeast Dna2 Protein, Which Is Related to the RecB-like Nucleases, Is Essential in Vivo

Saccharomyces cerevisiae Dna2 protein is required for DNA replication and repair and is associated with multiple biochemical activities: DNA-dependent ATPase, DNA helicase, and DNA nuclease. To investigate which of these activities is important for the cellular functions of Dna2, we have identified separation of function mutations that selectively inactivate the helicase or nuclease. We describe the effect of six such mutations on ATPase, helicase, and nuclease after purification of the mutant proteins from yeast or baculovirus-infected insect cells. A mutation in the Walker A box in the C-terminal third of the protein affects helicase and ATPase but not nuclease; a mutation in the N-terminal domain (amino acid 504) affects ATPase, helicase, and nuclease. Two mutations in the N-terminal domain abolish nuclease but do not reduce helicase activity (amino acids 657 and 675) and identify the putative nuclease active site. Two mutations immediately adjacent to the proposed nuclease active site (amino acids 640 and 693) impair nuclease activity in the absence of ATP but completely abolish nuclease activity in the presence of ATP. These results suggest that, although the Dna2 helicase and nuclease activities can be independently affected by some mutations, the two activities appear to interact, and the nuclease activity is regulated in a complex manner by ATP. Physiological analysis shows that both ATPase and nuclease are important for the essential function of DNA2 in DNA replication and for its role in double-strand break repair. Four of the nuclease mutants are not only loss of function mutations but also exhibit a dominant negative phenotype

The variation of relative magnetic helicity around major flares

We have investigated the variation of magnetic helicity over a span of several days around the times of 11 X-class flares which occurred in seven active regions (NOAA 9672, 10030, 10314, 10486, 10564, 10696, and 10720) using the magnetograms taken by the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO). As a major result we found that each of these major flares was preceded by a significant helicity accumulation over a long period (0.5 to a few days). Another finding is that the helicity accumulates at a nearly constant rate and then becomes nearly constant before the flares. This led us to distinguish the helicity variation into two phases: a phase of monotonically increasing helicity and the following phase of relatively constant helicity. As expected, the amount of helicity accumulated shows a modest correlation with time-integrated soft X-ray flux during flares. However, the average helicity change rate in the first phase shows even stronger correlation with the time-integrated soft X-ray flux. We discuss the physical implications of this result and the possibility that this characteristic helicity variation pattern can be used as an early warning sign for solar eruptions

Nonlinear Effects in Three-minute Oscillations of the Solar Chromosphere. I. An Analytical Nonlinear Solution and Detection of the Second Harmonic

The vertical propagation of nonlinear acoustic waves in an isothermal atmosphere is considered. A new analytical solution that describes a finite-amplitude wave of an arbitrary wavelength is obtained. Although the short- and long-wavelength limits were previously considered separately, the new solution describes both limiting cases within a common framework and provides a straightforward way of interpolating between the two limits. Physical features of the nonlinear waves in the chromosphere are described, including the dispersive nature of low-frequency waves, the steepening of the wave profile, and the influence of the gravitational field on wavefront breaking and shock formation. The analytical results suggest that observations of three-minute oscillations in the solar chromosphere may reveal the basic nonlinear effect of oscillations with combination frequencies, superposed on the normal oscillations of the system. Explicit expressions for a second-harmonic signal and the ratio of its amplitude to the fundamental harmonic amplitude are derived. Observational evidence of the second harmonic, obtained with the Fast Imaging Solar Spectrograph, installed at the 1.6 m New Solar Telescope of the Big Bear Observatory, is presented. The presented data are based on the time variations of velocity determined from the Na i D₂ and Hα lines

Lethality or improved growth as a result of interaction in DNA repair double mutants of Aspergillus

Genetic analysis recently identified nine new DNA repair genes of Aspergillus nidulans, musK - musS, which map on several different chromosomes (Käfer 1994, preceding article in this Newsletter). Such mus mutants are sensitive to certain chemical mutagens, but not sensitive or only slightly sensitive to UV and gamma-radiation. To identify epistatic interactions with members of the 4 Uvs groups, double mutants strains were isolated (Käfer and Chae 1994 Curr. Genet. 25:223-232). However, some mus;uvs double mutants could not be analyzed because they grew too poorly or were lethal (showing synthetic enhancement in gene interaction ; Guarente 1993 Trends Genet. 9:362-366). The opposite effect was also found; namely interaction which led to improved recovery and growth (or rescue ) as documented here

Nonexistence of self-similar singularities for the 3D incompressible Euler equations

We prove that there exists no self-similar finite time blowing up solution to the 3D incompressible Euler equations. By similar method we also show nonexistence of self-similar blowing up solutions to the divergence-free transport equation in $\Bbb R^n$. This result has direct applications to the density dependent Euler equations, the Boussinesq system, and the quasi-geostrophic equations, for which we also show nonexistence of self-similar blowing up solutions.Comment: This version refines the previous one by relaxing the condition of compact support for the vorticit