Synthesis of structural damping, volume I Final report

Hysteresis model for analyzing dynamic behavior of complex structure

Antimatter from supersymmetric dark matter

We propose low-energy antideuterons in cosmic rays as a new possible signature for indirect detection of supersymmetric dark matter. Since the energy spectrum of the antiproton secondary component is still spoilt by considerable theoretical uncertainties, looking for low-energy antideuterons seems a plausible alternative. We apply our calculation to the AMS experiment, when mounted on the International Spatial Station. If a few low-energy antideuterons will be discovered by AMS, this should be seriously taken as a clue for the existence of relic, massive neutralinos in the dark halo of our Galaxy.Comment: 8 pages, 8 figures, Talk presented at the 4th International Symposium On Sources And Detection Of Dark Matter In The Universe (DM 2000), Marina del Rey, California, 23-25 Feb. 200

Transport of cross helicity and radial evolution of alfvenicity in the solar wind

A transport theory including cross helicity, magnetohydrodynamic(MHD) turbulence, and driving by shear and pickup ions, is applied to the radial evolution of the solar wind. The radial decrease of cross helicity observed in the solar wind can be accounted for when sufficient driving is included to overcome the inherent tendency for MHD turbulence to produce Alfvenic states

Radial evolution of cross helicity at low and high latitudes in the solar wind

We employ a turbulence transport theory to the radial evolution of the solar wind at both low and high latitudes. The theory includes cross helicity, magnetohydrodynamic (MHD) turbulence, and driving by shear and pickup ions. The radial decrease of cross helicity, observed in both low and high latitudes, can be accounted for by including sufficient shear driving to overcome the tendency of MHD turbulence to produce Alfvénic states. The shear driving is weaker at high latitudes leading to a slower evolution. Model results are compared with observations from Ulysses and Voyager

Radial evolution of cross helicity in high-latitude solar wind

We employ a turbulence transport theory to explain the high-latitude radial evolution of cross helicity, or Alfvénicity, observed by the Ulysses spacecraft. Evolution is slower than at low latitudes due to weakened shear driving

Measurement of the electric fluctuation spectrum of magnetohydrodynamic turbulence

Magnetohydrodynamic (MHD) turbulence in the solar wind is observed to show the spectral behavior of classical Kolmogorov fluid turbulence over an inertial subrange and departures from this at short wavelengths, where energy should be dissipated. Here we present the first measurements of the electric field fluctuation spectrum over the inertial and dissipative wavenumber ranges in a $\beta \gtrsim 1$ plasma. The $k^{-5/3}$ inertial subrange is observed and agrees strikingly with the magnetic fluctuation spectrum; the wave phase speed in this regime is shown to be consistent with the Alfv\'en speed. At smaller wavelengths $k \rho_i \geq 1$ the electric spectrum is softer and is consistent with the expected dispersion relation of short-wavelength kinetic Alfv\'en waves. Kinetic Alfv\'en waves damp on the solar wind ions and electrons and may act to isotropize them. This effect may explain the fluid-like nature of the solar wind.Comment: submitted; 4 pages + 3 figure

Comparison of performance and fitness traits in German Angler, Swedish Red and Swedish Polled with Holstein dairy cattle breeds under organic production

Although the use of local breeds is recommended by organic regulations, breed comparisons performed under organic production conditions with similar production intensities are scarce. Therefore, we compared data of local and widely used Holstein dairy cattle breeds from 2011 to 2015 regarding production, fertility and health from German and Swedish organic farms with similar management intensities within country. In Germany, the energy-corrected total milk yield tended to be lower in the local breed Original Angler Cattle (AAZ, 5193 kg) compared to the modern German Holstein Friesian breed (HO, 5620 kg), but AAZ showed higher milk fat and protein contents (AAZ v. HO: 5.09% v. 4.18% and 3.61% v. 3.31%, respectively). In Sweden, the widely used modern Swedish Holstein (SH) breed had the highest milk yield (9209 kg, fat: 4.10%, protein: 3.31%), while the local Swedish Polled (SKB) showed highest milk yield, fat and protein contents (6169 kg, 4.47%, 3.50%, respectively), followed by the local breed Swedish Red (SRB, 8283 kg, 4.33%, 3.46%, respectively). With regard to fertility characteristics, the German breeds showed no differences, but AAZ tended to have less days open compared to HO (−17 days). In Sweden, breeds did not differ with regard to calving interval, but both local breeds showed a lower number of days open (−10.4 in SRB and −24.1 in SKB compared to SH), and SKB needed fewer inseminations until conception (−0.5 inseminations) compared to SH. Proportion of test day records with a somatic cell count content of ≥100 000 cells per ml milk did not reveal breed differences in any of the two countries. German breeds did not differ regarding the proportion of cows with veterinary treatments. In Sweden, SRB showed the lowest proportion of cows with general veterinary treatment as well as specific treatment due to udder problems (22.8 ± 6.42 and 8.05 ± 2.18, respectively), but the local breed SKB did not differ from SH in either of the two traits. In Sweden, we found no breed differences regarding veterinary treatments due to fertility problems or diagnosis of claw or leg problems during claw trimming. Our results indicate a stronger expression of the antagonism between production and functional traits with increasing production intensity. Future breed comparisons, therefore, need to consider different production intensities within organic farming in order to derive practical recommendations as to how to implement European organic regulations with regard to a suitable choice of breeds

Model-based spacecraft and mission design for the evaluation of technology

In order to meet the future vision of robotic missions, engineers will face intricate mission concepts, new operational approaches, and technologies that have yet to be developed. The concept of smaller, model driven projects helps this transition by including life-cycle cost as part of the decision making process. For example, since planetary exploration missions have cost ceilings and short development periods, heritage flight hardware is utilized. However, conceptual designs that rely solely on heritage technology will result in estimates that may not be truly representative of the actual mission being designed and built. The Laboratory for Spacecraft and Mission Design (LSMD) at the California Institute of Technology is developing integrated concurrent models for mass and cost estimations. The purpose of this project is to quantify the infusion of specific technologies where the data would be useful in guiding technology developments leading up to a mission. This paper introduces the design-to-cost model to determine the implications of various technologies on the spacecraft system in a collaborative engineering environment. In addition, comparisons of the benefits of new or advanced technologies for future deep space missions are examined

Spin-polarization-induced structural selectivity in Pd3X_3X and Pt3X_3X (X=3dX=3d) compounds

Spin-polarization is known to lead to important {\it magnetic} and {\it optical} effects in open-shell atoms and elemental solids, but has rarely been implicated in controlling {\it structural} selectivity in compounds and alloys. Here we show that spin-polarized electronic structure calculations are crucial for predicting the correct $T=0$ crystal structures for Pd$_3X$ and Pt$_3X$ compounds. Spin-polarization leads to (i) stabilization of the $L1_2$ structure over the $DO_{22}$ structure in Pt$_3$Cr, Pd$_3$Cr, and Pd$_3$Mn, (ii) to the stabilization of the $DO_{22}$ structure over the $L1_2$ structure in Pd$_3$Co and to (iii) ordering (rather than phase-separation) in Pt$_3$Co and Pd$_3$Cr. The results are analyzed in terms of first-principles local spin density calculations.Comment: 4 pages, REVTEX, 3 eps figures, to appear in PR