Gravitational waveforms from the evaporating ACO cosmic string loop

The linearly polarized gravitational waveforms from a certain type of rotating, evaporating cosmic string - the Allen-Casper-Ottewill loop - are constructed and plotted over the lifetime of the loop. The formulas for the waveforms are simple and exact, and describe waves which attenuate self-similarly, with the amplitude and period of the waves falling off linearly with time.Comment: 30 pages, 16 figure

MeV Right-handed Neutrinos and Dark Matter

We consider the possibility of having a MeV right-handed neutrino as a dark matter constituent. The initial reason for this study was the 511 keV spectral line observed by the satellite experiment INTEGRAL: could it be due to an interaction between dark matter and baryons? Independently of this, we find a number of constraints on the assumed right-handed interactions. They arise in particular from the measurements by solar neutrino experiments. We come to the conclusion that such particles interactions are possible, and could reproduce the peculiar angular distribution, but not the rate of the INTEGRAL signal. However, we stress that solar neutrino experiments are susceptible to provide further constraints in the future.Comment: 7 pages, figure 1 changed, added reference

The Problem of Inertia in Friedmann Universes

In this paper we study the origin of inertia in a curved spacetime, particularly the spatially flat, open and closed Friedmann universes. This is done using Sciama's law of inertial induction, which is based on Mach's principle, and expresses the analogy between the retarded far fields of electrodynamics and those of gravitation. After obtaining covariant expressions for electromagnetic fields due to an accelerating point charge in Friedmann models, we adopt Sciama's law to obtain the inertial force on an accelerating mass $m$ by integrating over the contributions from all the matter in the universe. The resulting inertial force has the form $F = -kma$, where $k < 1$ depends on the choice of the cosmological parameters such as $\Omega_{M}$, $\Omega_{\Lambda}$, and $\Omega_{R}$ and is also red-shift dependent.Comment: 10 page

Triple Experiment Spectrum of the Sunyaev-Zeldovich Effect in the Coma Cluster: H_0

The Sunyaev-Zeldovich (SZ) effect was previously measured in the Coma cluster by the Owens Valley Radio Observatory and Millimeter and IR Testa Grigia Observatory experiments and recently also with the Wilkinson Microwave Anisotropy Probe satellite. We assess the consistency of these results and their implications on the feasibility of high-frequency SZ work with ground-based telescopes. The unique data set from the combined measurements at six frequency bands is jointly analyzed, resulting in a best-fit value for the Thomson optical depth at the cluster center, tau_{0}=(5.35 \pm 0.67) 10^{-3}. The combined X-ray and SZ determined properties of the gas are used to determine the Hubble constant. For isothermal gas with a \beta density profile we derive H_0 = 84 \pm 26 km/(s\cdot Mpc); the (1\sigma) error includes only observational SZ and X-ray uncertainties.Comment: 11 pages, 1 figur

Limits on decaying dark energy density models from the CMB temperature-redshift relation

The nature of the dark energy is still a mystery and several models have been proposed to explain it. Here we consider a phenomenological model for dark energy decay into photons and particles as proposed by Lima (J. Lima, Phys. Rev. D 54, 2571 (1996)). He studied the thermodynamic aspects of decaying dark energy models in particular in the case of a continuous photon creation and/or disruption. Following his approach, we derive a temperature redshift relation for the CMB which depends on the effective equation of state $w_{eff}$ and on the "adiabatic index" $\gamma$. Comparing our relation with the data on the CMB temperature as a function of the redshift obtained from Sunyaev-Zel'dovich observations and at higher redshift from quasar absorption line spectra, we find $w_{eff}=-0.97 \pm 0.034$, adopting for the adiabatic index $\gamma=4/3$, in good agreement with current estimates and still compatible with $w_{eff}=-1$, implying that the dark energy content being constant in time.Comment: 8 pages, 1 figur

A solution for galactic disks with Yukawian gravitational potential

We present a new solution for the rotation curves of galactic disks with gravitational potential of the Yukawa type. We follow the technique employed by Toomre in 1963 in the study of galactic disks in the Newtonian theory. This new solution allows an easy comparison between the Newtonian solution and the Yukawian one. Therefore, constraints on the parameters of theories of gravitation can be imposed, which in the weak field limit reduce to Yukawian potentials. We then apply our formulae to the study of rotation curves for a zero-thickness exponential disk and compare it with the Newtonian case studied by Freeman in 1970. As an application of the mathematical tool developed here, we show that in any theory of gravity with a massive graviton (this means a gravitational potential of the Yukawa type), a strong limit can be imposed on the mass (m_g) of this particle. For example, in order to obtain a galactic disk with a scale length of b ~ 10 kpc, we should have a massive graviton of m_g << 10^{-59} g. This result is much more restrictive than those inferred from solar system observations.Comment: 7 pages; 1 eps figure; to appear in General Relativity and Gravitatio

Radiolabeled humanized anti-CD3 monoclonal antibody visilizumab for imaging human T-lymphocytes

Visilizumab is an IgG2 humanized monoclonal antibody (mAb) characterized by non-FcγR binding and specific to the CD3 antigen, expressed on more than 95% of circulating resting T-lymphocytes and on activated T-lymphocytes homing in inflamed tissues. We hypothesized that the use of a radiolabeled anti-CD3 antibody might serve as a diagnostic tool for imaging T-cell traffic and lymphocytic infiltration of tissues and organs affected by autoimmune diseases. Here we describe the results of in vitro and animal experiments with 99mTc-succinimidyl-6-hydrazinonicotinate hydrochloride (SHNH)-visilizumab. Methods: For mAb labeling, we used a 2-step method with a heterobifunctional linker SHNH. Several titrations were performed to obtain the best labeling efficiency. In vitro quality controls included stability assay, cysteine challenge, sodium dodecyl sulfate polyacrylamide gel electrophoresis, binding assay, and immunoreactivity assay. In vivo studies by high-resolution images were performed at 6 and 24 h after the injection of 99mTc-SHNH-visilizumab. These included cell-targeting experiments in BALB/c mice xenografted subcutaneously with an increasing number of HuT78 cells in the leg and displaced with an excess of cold antibody. We also studied irradiated severe combined immunodeficient (SCID) mice reconstituted with human peripheral blood mononuclear cells (hPBMCs) and injected with 99mTclabeled visilizumab or control mAb. After dynamic imaging for 3 h, major organs were removed, counted, and processed for immunohistologic examination. Results: Visilizumab was labeled with HYNIC with high labeling efficiency (>90%) and high specific activity (SA; 10,360-11,100 MBq/mg), with retained biochemical integrity and in vitro binding activity to CD3-positive cells. The in vivo targeting experiment showed a proportional increase of specific uptake with the number of injected cells, both at 6 and at 24 h, and the in vivo competition study demonstrated more than 60% decreased uptake after an excess of unlabeled antibody. In SCID mice, hPBMCs in different tissues were detected by 99mTc-labeled visilizumab and confirmed by histology. Conclusion: Visilizumab can be efficiently labeled with 99mTc with high efficiency and SA and could be a valuable tool for the study of human T-lymphocyte trafficking and lymphocytic infiltration of tissues and organs. Copyright © 2009 by the Society of Nuclear Medicine, Inc

MITO measurements of the Sunyaev-Zeldovich Effect in the Coma cluster of galaxies

We have measured the Sunyaev-Zeldovich effect towards the Coma cluster (A1656) with the MITO experiment, a 2.6-m telescope equipped with a 4-channel 17 arcminute (FWHM) photometer. Measurements at frequency bands 143+/-15, 214+/-15, 272+/-16 and 353+/-13 GHz, were made during 120 drift scans of Coma. We describe the observations and data analysis that involved extraction of the S-Z signal by employing a spatial and spectral de-correlation scheme to remove a dominant atmospheric component. The deduced values of the thermal S-Z effect in the first three bands are DT_{0} = -179+/-38,-33+/-81,170+/-35 microKelvin in the cluster center. The corresponding optical depth, tau=(4.1+/-0.9) 10^{-3}, is consistent (within errors) with both the value from a previous low frequency S-Z measurement, and the value predicted from the X-ray deduced gas parameters.Comment: Ap.J.Letters accepted, 4 pages, 2 figure

Cosmic ray tests of the D0 preshower detector

The D0 preshower detector consists of scintillator strips with embedded wavelength-shifting fibers, and a readout using Visible Light Photon Counters. The response to minimum ionizing particles has been tested with cosmic ray muons. We report results on the gain calibration and light-yield distributions. The spatial resolution is investigated taking into account the light sharing between strips, the effects of multiple scattering and various systematic uncertainties. The detection efficiency and noise contamination are also investigated.Comment: 27 pages, 24 figures, submitted to NIM