Cosmic ray biannual variation

The study of the cosmic ray (CR) power spectrum has revealed a significant variation with a period around 2 yr that cannot be explained as a high order harmonic of the 11 yr solar cycle. Comparative study of the correlation on different time scales between CR intensity and Rz, aa, high speed streams and polar hole size has put in evidence that a high degree of coherency exists between each couple of variables at 1.58 to 1.64 yr, except between CR and Rz. On the other hand cyclic variation on a short time scale, around 26 months, has been claimed to be present in the neutrino flux. Critical tests of this hypothesis are considered and a preliminary result seems to indicate that the hypothesis of the existence of a 1.6 yr periodicity in the neutrino data during the measurement time interval, has a significance or = 99.9%. The possible origin of this variation as due to a contribution either of CR interactions in the upper atmosphere or to the solar dynamics, are discussed

A study of periodicities and recurrences in solar activity and cosmic ray modulation

The 154d periodicity was found in the cosmic ray intensity (RE) vs Flares, and some other peaks of coherency in the RC vs aa sub I, that when interpreted as aliased values, might correspond to recurring interplanetary magnetic field structures and solar wind streams. It cannot be excluded, however, that some of the correspondence with aa are of terrestrial origin. This study cannot be considered exhaustive due to the fact that other solar variables, such as polar hole size, are possibly correlated to cosmic ray intensities. However, the number of observations is small so that the interpretation of the results is very difficult

Cosmic rays 10Be biennal data and their relationship to aurorae and sunspots

The galactic cosmic ray (C.R.) variations which should give information on three dimensional aspects of the heliospheric magnetic fields and on the solar wind, which modulate their influx into the Solar System were studied. In order to decode the information from the C.R. series it is necessary to know the mechanisms through which the modulation is produced. It it clear that a balance of effects with sources at different heliospheric latitudes results in the modulated C.R. intensity. It is found that the modulation of 10Be in polar ice may be due to at least two main contributions: (1) negative and in phase with the Solar flare activity modulating the cosmic ray flux in Forbush-type decreases, and (2) positive in phase with the appearance of large wind streams situated at both polar coronal holes. It is found that the high heliolatitude activity is related to a stable periodicity of 11.1y whereas the low heliolatitude activity contributes to the wondering of the solar cycles

Cosmic ray secular variations in terrestrial records and aurorae

The rediscovery that the Sun and the solar wind can undergo important changes on historical time scales has brought into question the stability of the cyclic behavior of past time series of solar and solar-terrestrial origin. It was found by Vector Fourier analysis that the solar 11 year cycle is present in the series of 10Be, delta 180, in ice cores and of thermoluminescence (TL) in sea sediments during the last Millennia with a frequency modulation, related to the Sun behavior, as tested by comparison with the Sunspot number R sub z series. It was shown that the cyclogram of the series of yearly Aurorae from 1721 to 1979 linear-regression-corrected-for-R sub z is straight for the periodicity zeta=11,1y, which indicates that such periodicity is constant in time corresponding to the only line present in the 11y band. The maxima of this component appear at the same time together with the high speed solar wind streams taking place in coronal holes situated in high heliolatitudes. It is evidenced that the 11 year cycle has undergone frequency oscillations on a time scale of two centuries, although it is very difficult to determine the periodicities with high accuracy

Ca II and CH+ interstellar absorption observations in the direction of resolvable binary stars

We report the initial results of a study to probe the small-scale structure in diffuse interstellar clouds by observing optical absorption lines of CH+ at 4232 °A and Ca II K at 3933 °A towards both components in resolvable binary systems. The data analysis is still in progress. To date, 70% of the Ca II spectra have been analyzed for the 19 observed systems. For half of these, a difference in the line strength or in the number of calcium components is found. The sightlines have been selected so that the observing method provides a potential probe of the small-scale structure of the interstellar medium in the range 200-4000 AU

Surface Functionalization of 3C-SiC Nanowires

One dimensional nanostrucures have potential applications in nanoscale electronic, optoelectronic or sensing devices. Core-shell nanowire (NW) structures of SiO2/β-SiC and SiC-NWs are interesting for fundamental studies and technological applications: 3C-SiC is particularly appealing because of its good physical, chemical properties and biocompatibility, offering opportunities for nano-scale devices operating in biological environment. Moreover, functionalized 3C-SiC nanowires have the potential to act as highly sensitive detector elements in bio-chemical field. Here, we report on the preliminary results of the functionalization of 3C-SiC nanowires with an optically active, thiophene-based, π-conjugated oligomer (PyT4). Oligothiophenes are semiconducting and fluorescent materials, widely used in organic electronics and biodiagnostic. SiC/SiO2 core/shell NWs grown by a Chemical Vapour Deposition (CVD) process on n-type Si (001) substrates, using carbon monoxide (CO) as the carbon source and nickel nitrate as the catalyst. The synthesis, performed at temperatures between 1050-1100?C. 3C-SiC NWs were grown in a home-made Vapor Phase Epitaxy (VPE) reactor using propane and silane as precursors (both diluted 3% in hydrogen) and a few nm of Ni as catalyst, deposited on Si(100) substrate using e-beam system. The nickel-deposited substrate is preheated at 1100?C for 5 minutes before introducing reagents for the grow time of 10 minutes. SiC/SiO2 core/shell NWs were then reacted with the triethoxysilane terminated with PyT4 to yield the hybrid NWs. The covalent grafting of the fluorophores was confirmed by fluorescence microscopy. The nanowires were further characterised by X-ray diffraction, Scanning Electron Microscopy, Cathodoluminescence and Transmission Electron Microscopy

A cooled telescope for measurements of the Near Infrared Cosmological Background at balloon altitude (TRIP Experiment)

A cooled telescope has been designed and prepared for measurements of both local and cosmological Near InfraRed Backgrounds in the waveband 1–5 mm at balloon altitude (40 km). The detection system consists of a linear array with 32 InSb pixels placed in the focal plane of the telescope, cryogenically cooled and thermally controlled. A short description is given of the main characteristics of the instrument and of the expected performances. The experiment, repeatedly tested in laboratory, flew in the 1995 summer from Palestine (Texas, USA)

Computational Cancer Biology: An Evolutionary Perspective

ISSN:1553-734XISSN:1553-735

Evolutionary Games with Affine Fitness Functions: Applications to Cancer

We analyze the dynamics of evolutionary games in which fitness is defined as an affine function of the expected payoff and a constant contribution. The resulting inhomogeneous replicator equation has an homogeneous equivalent with modified payoffs. The affine terms also influence the stochastic dynamics of a two-strategy Moran model of a finite population. We then apply the affine fitness function in a model for tumor-normal cell interactions to determine which are the most successful tumor strategies. In order to analyze the dynamics of concurrent strategies within a tumor population, we extend the model to a three-strategy game involving distinct tumor cell types as well as normal cells. In this model, interaction with normal cells, in combination with an increased constant fitness, is the most effective way of establishing a population of tumor cells in normal tissue.Comment: The final publication is available at http://www.springerlink.com, http://dx.doi.org/10.1007/s13235-011-0029-