Introduction: an overview of gravity sensing, perception, and signal transduction in animals and plants.

The antiquity of biological sensitivity and response to gravity can be traced through the ubiquity of morphology, mechanisms, and cellular events in gravity sensing biological systems in the most diverse species of both plants and animals. Further, when we examine organisms at the cellular level to elucidate the molecular mechanism by which a gravitational signal is transduced into a biochemical response, the distinction between plants and animals becomes blurred.     

Induction of high grade astrocytoma (HGA) by protons: molecular mechanisms and RBE considerations.

Protons of a specific energy, 55 MeV, have been found to induce primary high grade astrocytomas (HGA) in the Rhesus monkey (Macaca mulatta). Brain tumors of this type were not induced by protons of other energies (32-2,300 MeV). Induction of HGA has been identified in human patients who have had radiation therapy to the head. We believe that the induction of HGA in the monkey is a consequence of dose distribution, not some unique "toxic" property of protons. Comparison of the human experience with the monkey data indicates the RBE for induction of brain tumors to be about one. It is unlikely that protons cause an unusual change in oncogenic expression, as compared to conventional electromagnetic radiation.     

XMM-Newton study of soft excess X-ray emission in clusters of galaxies

We discuss the detection of soft excess X-ray emission in a sample of 19 clusters of galaxies observed by XMM-Newton. In 6/19 clusters evidence for a soft X-ray excess is found. Four of these clusters show soft X-ray and O VII line emission from gas with a temperature of 0.2 keV. The centroid of this oxygen line is consistent with the redshift of the cluster. The intensity and spatial extend of the soft excess agrees with previous PSPC measurements. These observations are interpreted as emission from warm-hot intergalactic medium filaments, with density enhancements near the cluster centers, consistent with theoretical predictions. In the other two soft excess clusters a non-thermal origin is consistent with the data.     

Indicators of black-hole mass and Eddington accretion ratio from QSO X-ray and UV spectra

The evolution of luminous QSOs is linked to the evolution of massive galaxies. We know this because the relic black-holes found locally have masses dependent on the properties of the host galaxy’s bulge. An important way to explore this evolution would be to measure dependences of black-hole masses and Eddington accretion ratios over a range of redshifts, i.e., with cosmological age. For low redshift QSOs (and their lower luminosity Seyfert galaxy counterparts) it has been possible to infer black-hole masses from the luminosities and velocity dispersions of their host-galaxy bulges. These masses agree with those virial black-hole masses calculated from the Doppler widths of the broad Hβ emission lines. The latter method can then be extended to more distant and luminous QSOs, up to redshifts of 0.6 with ground-based optical observations. We discuss ways to extend these explorations to higher redshifts – up to 3 using the widths of QSOs’ broad UV emission lines, and in principle, and to redshifts near 4 from ground-based infrared observations of rest-frame Hβ at 2.5 μm. We discuss the possibility of investigating the accretion history of the higher redshift QSOs using measures of Eddington accretion ratio – the soft X-ray spectral index and the eigenvectors of Principal Components Analyses of QSOs’ UV emission-line spectra.     

Principal components in the PG-X-ray QSO sample

We have performed a spectral principal component analysis for a complete sample of 22 low redshift QSOs with spectra from Ly to H, and found three significant principal components, which account for 78% of the spectrum-to-spectrum variance. We present strong arguments that the first principal component represents the Baldwin effect, relating equivalent widths to the luminosity (i.e. accretion rate). The second component represents continuum variations, probably dominated by intrinsic reddening. The third principal component is directly related to broad emission-line width and X-ray spectral index, and therefore probably driven by Eddington accretion ratio, L/L_Edd. The third set of relationships tie directly to the optical Principal Component 1 found by Boroson and Green [Boroson, T., Green, R.F., Astrophys. J. Suppl. 80, 109, 1992 (BG92)], and are the primary cause of scatter in the Baldwin relationships.     

Real time localization of gamma ray bursts with INTEGRAL

The INTEGRAL satellite has been successfully launched in October 2002 and has recently started its operational phase. The INTEGRAL burst alert system (IBAS) will distribute in real time the coordinates of the gamma ray bursts (GRBs) detected with INTEGRAL. After a brief introduction on the INTEGRAL instruments, we describe the main IBAS characteristics and report on the initial results. During the initial performance and verification phase of the INTEGRAL mission, which lasted about two months, two GRBs have been localized with accuracy of 2–4 arcmin. These observations have allowed us to validate the IBAS software, which is now expected to provide quick (few seconds delay) and precise (few arcmin) localization for 10–15 GRBs per year.     

Measuring the matter distribution within z = 0.2 cluster lenses with XMM-Newton

We present an analysis of seven clusters observed by XMM-Newton as part of our survey of 17 most X-ray luminous clusters of galaxies at z  0.2 selected for a comprehensive and unbiased study of the mass distribution in massive clusters. Using the public software FTOOLS and XMMSAS we have set up an automated pipeline to reduce the EPIC MOS and pn spectro-imaging data, optimized for extended sources analysis. We also developped a code to perform intensive spectral and imaging analysis particularly focussing on proper background estimate and removal. XMM-Newton deep spectro-imaging of these clusters allowed us to fit a standard β-model to their gas emission profiles as well as a standard MEKAL emission model to their extracted spectra, and test their inferred characteristics against already calibrated relations.     

Uncertainties in estimates of the risks of late effects from space radiation.

Methods used to project risks in low-Earth orbit are of questionable merit for exploration missions because of the limited radiobiology data and knowledge of galactic cosmic ray (GCR) heavy ions, which causes estimates of the risk of late effects to be highly uncertain. Risk projections involve a product of many biological and physical factors, each of which has a differential range of uncertainty due to lack of data and knowledge. Using the linear-additivity model for radiation risks, we use Monte-Carlo sampling from subjective uncertainty distributions in each factor to obtain an estimate of the overall uncertainty in risk projections. The resulting methodology is applied to several human space exploration mission scenarios including a deep space outpost and Mars missions of duration of 360, 660, and 1000 days. The major results are the quantification of the uncertainties in current risk estimates, the identification of factors that dominate risk projection uncertainties, and the development of a method to quantify candidate approaches to reduce uncertainties or mitigate risks. The large uncertainties in GCR risk projections lead to probability distributions of risk that mask any potential risk reduction using the "optimization" of shielding materials or configurations. In contrast, the design of shielding optimization approaches for solar particle events and trapped protons can be made at this time and promising technologies can be shown to have merit using our approach. The methods used also make it possible to express risk management objectives in terms of quantitative metrics, e.g., the number of days in space without exceeding a given risk level within well-defined confidence limits.     

Quantifying the role of solar radiative forcing over the 20th century

The 20th century temperature anomaly record is reproduced using an energy balance model, with a diffusive deep ocean. The model takes into account all the standard radiative forcings, and in addition the possibility of a non-thermal solar component. The model is parameterized and then optimized to produce the most likely values for the climate parameters and radiative forcings which reproduce the 20th century global warming. We find that the best fit is obtained with a negligible net feedback. We also show that a non-thermal solar component is necessarily present, indicating that the total solar contribution to the 20th century global warming, of ΔT_solar = 0.27 ± 0.07 °C, is much larger than can be expected from variation in the total solar irradiance alone. However, we also find that the largest contribution to the 20th century warming comes from anthropogenic sources, with ΔT_man = 0.42 ± 0.11 °C.     

Probing the first stars and black holes in the early Universe with the Dark Ages Radio Explorer (DARE)

A concept for a new space-based cosmology mission called the Dark Ages Radio Explorer (DARE) is presented in this paper. DARE’s science objectives include: (1) When did the first stars form? (2) When did the first accreting black holes form? (3) When did Reionization begin? (4) What surprises does the end of the Dark Ages hold (e.g., Dark Matter decay)? DARE will use the highly-redshifted hyperfine 21-cm transition from neutral hydrogen to track the formation of the first luminous objects by their impact on the intergalactic medium during the end of the Dark Ages and during Cosmic Dawn (redshifts z = 11–35). It will measure the sky-averaged spin temperature of neutral hydrogen at the unexplored epoch 80–420 million years after the Big Bang, providing the first evidence of the earliest stars and galaxies to illuminate the cosmos and testing our models of galaxy formation. DARE’s approach is to measure the expected spectral features in the sky-averaged, redshifted 21-cm signal over a radio bandpass of 40–120 MHz. DARE orbits the Moon for a mission lifetime of 3 years and takes data above the lunar farside, the only location in the inner solar system proven to be free of human-generated radio frequency interference and any significant ionosphere. The science instrument is composed of a low frequency radiometer, including electrically-short, tapered, bi-conical dipole antennas, a receiver, and a digital spectrometer. The smooth frequency response of the antennas and the differential spectral calibration approach using a Markov Chain Monte Carlo technique will be applied to detect the weak cosmic 21-cm signal in the presence of the intense solar system and Galactic foreground emissions.