On the extrapolation to ITER of discharges in present tokamaks

An expression for the extrapolated fusion gain G = Pfusion /5 Pheat (Pfusion being the total fusion power and Pheat the total heating power) of ITER in terms of the confinement improvement factor (H) and the normalised beta (betaN) is derived in this paper. It is shown that an increase in normalised beta can be expected to have a negative or neutral influence on G depending on the chosen confinement scaling law. Figures of merit like H betaN / q95^2 should be used with care, since large values of this quantity do not guarantee high values of G, and might not be attainable with the heating power installed on ITER.Comment: 6 Pages, 3 figures, Submitted to Nuclear Fusion on the 29th of November 200

High-Redshift Cosmography

We constrain the parameters describing the kinematical state of the universe using a cosmographic approach, which is fundamental in that it requires a very minimal set of assumptions (namely to specify a metric) and does not rely on the dynamical equations for gravity. On the data side, we consider the most recent compilations of Supernovae and Gamma Ray Bursts catalogues. This allows to further extend the cosmographic fit up to $z = 6.6$, i.e. up to redshift for which one could start to resolve the low z degeneracy among competing cosmological models. In order to reliably control the cosmographic approach at high redshifts, we adopt the expansion in the improved parameter $y = z/(1+z)$. This series has the great advantage to hold also for $z > 1$ and hence it is the appropriate tool for handling data including non-nearby distance indicators. We find that Gamma Ray Bursts, probing higher redshifts than Supernovae, have constraining power and do require (and statistically allow) a cosmographic expansion at higher order than Supernovae alone. Exploiting the set of data from Union and GRBs catalogues, we show (for the first time in a purely cosmographic approach parametrized by deceleration $q_0$, jerk $j_0$, snap $s_0$) a definitively negative deceleration parameter $q_0$ up to the 3$\sigma$ confidence level. We present also forecasts for realistic data sets that are likely to be obtained in the next few years.Comment: 16 pages, 6 figures, 3 tables. Improved version matching the published one, additional comments and reference

Equation of State of Oscillating Brans-Dicke Scalar and Extra Dimensions

We consider a Brans-Dicke scalar field stabilized by a general power law potential with power index $n$ at a finite equilibrium value. Redshifting matter induces oscillations of the scalar field around its equilibrium due to the scalar field coupling to the trace of the energy momentum tensor. If the stabilizing potential is sufficiently steep these high frequency oscillations are consistent with observational and experimental constraints for arbitrary value of the Brans-Dicke parameter $\omega$. We study analytically and numerically the equation of state of these high frequency oscillations in terms of the parameters $\omega$ and $n$ and find the corresponding evolution of the universe scale factor. We find that the equation of state parameter can be negative and less than -1 but it is not related to the evolution of the scale factor in the usual way. Nevertheless, accelerating expansion is found for a certain parameter range. Our analysis applies also to oscillations of the size of extra dimensions (the radion field) around an equilibrium value. This duality between self-coupled Brans-Dicke and radion dynamics is applicable for $\omega= -1 + 1/D$ where D is the number of extra dimensions.Comment: 10 two-column pages, RevTex4, 8 figures. Added clarifying discussions, new references. Accepted in Phys. Rev. D (to appear

R-parity preserving super-WIMP decays

We point out that when the decay of one electroweak scale super-WIMP state to another occurs at second order in a super-weak coupling constant, this can naturally lead to decay lifetimes that are much larger than the age of the Universe, and create observable consequences for the indirect detection of dark matter. We demonstrate this in a supersymmetric model with Dirac neutrinos, where the right-handed scalar neutrinos are the lightest and next-to-lightest supersymmetric partners. We show that this model produces a super-WIMP decay rate scaling as m_nu^4/(weak scale)^3, and may significantly enhance the fraction of energetic electrons and positrons over anti-protons in the decay products. Such a signature is consistent with the observations recently reported by the PAMELA experiment.Comment: 14 pages, v3 JHEP versio

Current constraints on Cosmological Parameters from Microwave Background Anisotropies

We compare the latest observations of Cosmic Microwave Background (CMB) Anisotropies with the theoretical predictions of the standard scenario of structure formation. Assuming a primordial power spectrum of adiabatic perturbations we found that the total energy density is constrained to be $\Omega_{tot}=1.03\pm0.06$ while the energy density in baryon and Cold Dark Matter (CDM) are $\Omega_bh^2=0.021\pm0.003$ and $\Omega_{cdm}h^2=0.12\pm0.02$, (all at 68% C.L.) respectively. The primordial spectrum is consistent with scale invariance, ($n_s=0.97\pm0.04$) and the age of the universe is $t_0=14.6\pm0.9$ Gyrs. Adding informations from Large Scale Structure and Supernovae, we found a strong evidence for a cosmological constant $\Omega_{\Lambda}=0.70_{-0.05}^{+0.07}$ and a value of the Hubble parameter $h=0.69\pm0.07$. Restricting this combined analysis to flat universes, we put constraints on possible 'extensions' of the standard scenario. A gravity waves contribution to the quadrupole anisotropy is limited to be $r \le 0.42$ (95% c.l.). A constant equation of state for the dark energy component is bound to be $w_Q \le -0.74$ (95% c.l.). We constrain the effective relativistic degrees of freedom $N_\nu \leq 6.2$ and the neutrino chemical potential $-0.01 \leq \xi_e \leq 0.18$ and $|\xi_{\mu,\tau}|\leq 2.3$ (massless neutrinos).Comment: The status of cosmological parameters before WMAP. In press on Phys. Rev. D., Rapid Communication, 6 pages, 5 figure

Is cosmology consistent?

We perform a detailed analysis of the latest CMB measurements (including BOOMERaNG, DASI, Maxima and CBI), both alone and jointly with other cosmological data sets involving, e.g., galaxy clustering and the Lyman Alpha Forest. We first address the question of whether the CMB data are internally consistent once calibration and beam uncertainties are taken into account, performing a series of statistical tests. With a few minor caveats, our answer is yes, and we compress all data into a single set of 24 bandpowers with associated covariance matrix and window functions. We then compute joint constraints on the 11 parameters of the ``standard'' adiabatic inflationary cosmological model. Out best fit model passes a series of physical consistency checks and agrees with essentially all currently available cosmological data. In addition to sharp constraints on the cosmic matter budget in good agreement with those of the BOOMERaNG, DASI and Maxima teams, we obtain a heaviest neutrino mass range 0.04-4.2 eV and the sharpest constraints to date on gravity waves which (together with preference for a slight red-tilt) favors ``small-field'' inflation models.Comment: Replaced to match accepted PRD version. 14 pages, 12 figs. Tiny changes due to smaller DASI & Maxima calibration errors. Expanded neutrino and tensor discussion, added refs, typos fixed. Combined CMB data, window and covariance matrix at http://www.hep.upenn.edu/~max/consistent.html or from [email protected]

Curvatons in Supersymmetric Models

We study the curvaton scenario in supersymmetric framework paying particular attention to the fact that scalar fields are inevitably complex in supersymmetric theories. If there are more than one scalar fields associated with the curvaton mechanism, isocurvature (entropy) fluctuations between those fields in general arise, which may significantly affect the properties of the cosmic density fluctuations. We examine several candidates for the curvaton in the supersymmetric framework, such as moduli fields, Affleck-Dine field, $F$- and $D$-flat directions, and right-handed sneutrino. We estimate how the isocurvature fluctuations generated in each case affect the cosmic microwave background angular power spectrum. With the use of the recent observational result of the WMAP, stringent constraints on the models are derived and, in particular, it is seen that large fraction of the parameter space is excluded if the Affleck-Dine field plays the role of the curvaton field. Natural and well-motivated candidates of the curvaton are also listed.Comment: 34 pages, 5 figure

High-throughput ultrastructure screening using electron microscopy and fluorescent barcoding.

Genetic screens using high-throughput fluorescent microscopes have generated large datasets, contributing many cell biological insights. Such approaches cannot tackle questions requiring knowledge of ultrastructure below the resolution limit of fluorescent microscopy. Electron microscopy (EM) reveals detailed cellular ultrastructure but requires time-consuming sample preparation, limiting throughput. Here we describe a robust method for screening by high-throughput EM. Our approach uses combinations of fluorophores as barcodes to uniquely mark each cell type in mixed populations and correlative light and EM (CLEM) to read the barcode of each cell before it is imaged by EM. Coupled with an easy-to-use software workflow for correlation, segmentation, and computer image analysis, our method, called "MultiCLEM," allows us to extract and analyze multiple cell populations from each EM sample preparation. We demonstrate several uses for MultiCLEM with 15 different yeast variants. The methodology is not restricted to yeast, can be scaled to higher throughput, and can be used in multiple ways to enable EM to become a powerful screening technique.This work was financially supported by grants from the Deutsche Forschungsgemeinschaft (SFB1129 Z2 to J.A.G. Briggs), EMBL (to J.A.G. Briggs), the Medical Research Council (MC_UP_1201/16 to J.A.G. Briggs), and the German Ministry of Education and Research (031A605 to K.R. Patil). The Schuldiner laboratory is supported by the European Research Council CoG 646604 Peroxisystem, the Deutsche Forschungsgemeinschaft (grant SFB1190 and a Deutsch-Israelische Projektkooperation [DIP] collaborative grant). N. Gabrielli was supported by the EMBL interdisciplinary postdoctoral program. M. Schuldiner is an incumbent of the Dr. Gilbert Omenn and Martha Darling Professorial Chair in Molecular Genetics