Potential landing sites for Mars Pathfinder

In addition to a better understanding of the geological evolution of Mars, new techniques for processing available data have emerged, new data have been acquired, and the engineering approaches for placing spacecraft on the surface have evolved. Selection of the Mars Pathfinder landing site must take these issues into account, along with mission constraints. An advantage of Mars Pathfinder is the rover for sampling surface materials over a range of tens of meters. However, engineering constraints and the limited scientific payload of this mission require new approaches for landing site selection. One approach is to select sites exhibiting a wide variety of rocks near the lander. An alternative approach is to select sites in which the regional geology consists of a single rock type representing a key datum for the geological study of Mars, and is uniformly distributed within the landing ellipse

Lorentz invariance violation in top-down scenarios of ultrahigh energy cosmic ray creation

The violation of Lorentz invariance (LI) has been invoked in a number of ways to explain issues dealing with ultrahigh energy cosmic ray (UHECR) production and propagation. These treatments, however, have mostly been limited to examples in the proton-neutron system and photon-electron system. In this paper we show how a broader violation of Lorentz invariance would allow for a series of previously forbidden decays to occur, and how that could lead to UHECR primaries being heavy baryonic states or Higgs bosons.Comment: Replaced with heavily revised (see new Abstract) version accepted by Phys. Rev. D. 6 page

Relief and geology of the north polar region of the planet Venus

Description of topographic features is given for the North polar region of the planet Venus. Principal geomorphic types of terrain are characterized as well as their geologic relations. Relative ages of geologic units in Venus North polar region are discussed

Dynamics and thermodynamics of axisymmetric flows: I. Theory

We develop new variational principles to study stability and equilibrium of axisymmetric flows. We show that there is an infinite number of steady state solutions. We show that these steady states maximize a (non-universal) $H$-function. We derive relaxation equations which can be used as numerical algorithm to construct stable stationary solutions of axisymmetric flows. In a second part, we develop a thermodynamical approach to the equilibrium states at some fixed coarse-grained scale. We show that the resulting distribution can be divided in a universal part coming from the conservation of robust invariants and one non-universal determined by the initial conditions through the fragile invariants (for freely evolving systems) or by a prior distribution encoding non-ideal effects such as viscosity, small-scale forcing and dissipation (for forced systems). Finally, we derive a parameterization of inviscid mixing to describe the dynamics of the system at the coarse-grained scale

Synthesis and research of polyfunctional silylureas used in electric deposition of tin-indium alloy

Polyfunctional silylureas were synthesized by the interaction of 3-aminopropyltriethoxysilane with isocyanates of various structures in an inert aromatic solvent. Commercially available diisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, 2,4-toluene diisocyanate were used as isocyanates. In this case, freshly distilled toluene was used as a solvent. The structures of the obtained compounds were confirmed by the data of IR and NMR1H spectroscopy. Using the synthesized compounds, formulations of compositions for electrodeposition of a tin-indium alloy on a copper wire were developed. The possibility of using silylureas of various structures as effective surfactants used in the electrodeposition of the tin-indium alloy is shown. The operational characteristics of the obtained wire were investigated, including the wire diameter, coating thickness, tensile strength, electrical resistance, and direct current electrical resistivity

Global anisotropy of arrival directions of ultra-high-energy cosmic rays: capabilities of space-based detectors

Planned space-based ultra-high-energy cosmic-ray detectors (TUS, JEM-EUSO and S-EUSO) are best suited for searches of global anisotropies in the distribution of arrival directions of cosmic-ray particles because they will be able to observe the full sky with a single instrument. We calculate quantitatively the strength of anisotropies associated with two models of the origin of the highest-energy particles: the extragalactic model (sources follow the distribution of galaxies in the Universe) and the superheavy dark-matter model (sources follow the distribution of dark matter in the Galactic halo). Based on the expected exposure of the experiments, we estimate the optimal strategy for efficient search of these effects.Comment: 19 pages, 7 figures, iopart style. v.2: discussion of the effect of the cosmic magnetic fields added; other minor changes. Simulated UHECR skymaps available at http://livni.inr.ac.ru/UHECRskymaps

Spontaneous annihilation of high-density matter in the electroweak theory

In the presence of fermionic matter the topologically distinct vacua of the standard model are metastable and can decay by tunneling through the sphaleron barrier. This process annihilates one fermion per doublet due to the anomalous non-conservation of baryon and lepton currents and is accompanied by a production of gauge and Higgs bosons. We present a numerical method to obtain local bounce solutions which minimize the Euclidean action in the space of all configurations connecting two adjacent topological sectors. These solutions determine the decay rate and the configuration of the fields after the tunneling. We also follow the real time evolution of this configuration and analyze the spectrum of the created bosons. If the matter density exceeds some critical value, the exponentially suppressed tunneling triggers off an avalanche producing an enormous amount of bosons.Comment: 38 pages, 6 Postscript figure

Neutrino-induced pion production from nuclei at medium energies

We present a fully relativistic formalism for describing neutrino-induced $\Delta$-mediated single-pion production from nuclei. We assess the ambiguities stemming from the $\Delta$ interactions. Variations in the cross sections of over 10% are observed, depending on whether or not magnetic-dipole dominance is assumed to extract the vector form factors. These uncertainties have a direct impact on the accuracy with which the axial-vector form factors can be extracted. Different predictions for $C_5^A(Q^2)$ induce up to 40-50% effects on the $\Delta$-production cross sections. To describe the nucleus, we turn to a relativistic plane-wave impulse approximation (RPWIA) using realistic bound-state wave functions derived in the Hartree approximation to the $\sigma$-$\omega$ Walecka model. For neutrino energies larger than 1 GeV, we show that a relativistic Fermi-gas model with appropriate binding-energy correction produces comparable results as the RPWIA which naturally includes Fermi motion, nuclear-binding effects and the Pauli exclusion principle. Including $\Delta$ medium modifications yields a 20 to 25% reduction of the RPWIA cross section. The model presented in this work can be naturally extended to include the effect of final-state interactions in a relativistic and quantum-mechanical way. Guided by recent neutrino-oscillation experiments, such as MiniBooNE and K2K, and future efforts like MINER$\nu$A, we present $Q^2$, $W$, and various semi-inclusive distributions, both for a free nucleon and carbon, oxygen and iron targets.Comment: 25 pages, 14 figure

Hamiltonian formulation of tetrad gravity: three dimensional case

The Hamiltonian formulation of the tetrad gravity in any dimension higher than two, using its first order form when tetrads and spin connections are treated as independent variables, is discussed and the complete solution of the three dimensional case is given. For the first time, applying the methods of constrained dynamics, the Hamiltonian and constraints are explicitly derived and the algebra of the Poisson brackets among all constraints is calculated. The algebra of the Poisson brackets among first class secondary constraints locally coincides with Lie algebra of the ISO(2,1) Poincare group. All the first class constraints of this formulation, according to the Dirac conjecture and using the Castellani procedure, allow us to unambiguously derive the generator of gauge transformations and find the gauge transformations of the tetrads and spin connections which turn out to be the same found by Witten without recourse to the Hamiltonian methods [\textit{Nucl. Phys. B 311 (1988) 46}]. The gauge symmetry of the tetrad gravity generated by Lie algebra of constraints is compared with another invariance, diffeomorphism. Some conclusions about the Hamiltonian formulation in higher dimensions are briefly discussed; in particular, that diffeomorphism invariance is \textit{not derivable} as a \textit{gauge symmetry} from the Hamiltonian formulation of tetrad gravity in any dimension when tetrads and spin connections are used as independent variables.Comment: 31 pages, minor corrections, references are added, to appear in Gravitation & Cosmolog