229 research outputs found

    On general features of warm dark matter with reduced relativistic gas

    Full text link
    Reduced Relativistic Gas (RRG) is a useful approach to describe the warm dark matter (WDM) or the warmness of baryonic matter in the approximation when the interaction between the particles is irrelevant. The use of Maxwell distribution leads to the complicated equation of state of the J\"{u}ttner model of relativistic ideal gas. The RRG enables one to reproduce the same physical situation but in a much simpler form. For this reason RRG can be a useful tool for the theories with some sort of a "new Physics". On the other hand, even without the qualitatively new physical implementations, the RRG can be useful to describe the general features of WDM in a model-independent way. In this sense one can see, in particular, to which extent the cosmological manifestations of WDM may be dependent on its Particle Physics background. In the present work RRG is used as a complementary approach to derive the main observational exponents for the WDM in a model-independent way. The only assumption concerns a non-negligible velocity vv for dark matter particles which is parameterized by the warmness parameter bb. The relatively high values of bb ( b2≳10−6b^2\gtrsim 10^{-6}) erase the radiation (photons and neutrinos) dominated epoch and cause an early warm matter domination after inflation. Furthermore, RRG approach enables one to quantify the lack of power in linear matter spectrum at small scales and in particular, reproduces the relative transfer function commonly used in context of WDM with accuracy of ≲1%\lesssim 1\%. A warmness with b2≲10−6b^2\lesssim 10^{-6} (equivalent to v≲300km/sv\lesssim 300 km/s) does not alter significantly the CMB power spectrum and is in agreement with the background observational tests.Comment: 15 pages, 8 figures. Essential improvements in style and presentatio

    Parcels and particles: Markov blankets in the brain

    Get PDF
    At the inception of human brain mapping, two principles of functional anatomy underwrote most conceptions—and analyses—of distributed brain responses: namely, functional segregation and integration. There are currently two main approaches to characterizing functional integration. The first is a mechanistic modeling of connectomics in terms of directed effective connectivity that mediates neuronal message passing and dynamics on neuronal circuits. The second phenomenological approach usually characterizes undirected functional connectivity (i.e., measurable correlations), in terms of intrinsic brain networks, self-organized criticality, dynamical instability, and so on. This paper describes a treatment of effective connectivity that speaks to the emergence of intrinsic brain networks and critical dynamics. It is predicated on the notion of Markov blankets that play a fundamental role in the self-organization of far from equilibrium systems. Using the apparatus of the renormalization group, we show that much of the phenomenology found in network neuroscience is an emergent property of a particular partition of neuronal states, over progressively coarser scales. As such, it offers a way of linking dynamics on directed graphs to the phenomenology of intrinsic brain networks

    Increasing the length of EM-9 interstock enhances production efficiency in Imperial Gala apples.

    Get PDF
    The objective of this study was to evaluate the influence of different lengths of EM-9 interstock, on the production and fruit characteristics of Imperial Gala apples more than eight years old. This experiment was conducted in a commercial orchard located in Vacaria-RS, Brazil, situated at an altitude of 955 m , during seasons 2005/06, 2007/08, 2010/11, 2011/12 and 2012/13. The treatments consisted of five lengths of EM-9 interstock (10, 15, 20, 25 and 30 cm) connecting the Marubakaido rootstock to the Imperial Gala scion. For production efficiency a positive correlation between increased efficiency and the length of interstock was observed. Likewise a positive correlation was also noted for quality parameters of the fruit; firmness and classification (Category 1). From this study we conclude that a EM-9 interstock of 30 cm on Marubakaido rootstock is the most suitable for the vigor control of Imperial Gala apples, it ensures greater production efficiency and firmer fruit

    Bulk viscous cosmology with causal transport theory

    Full text link
    We consider cosmological scenarios originating from a single imperfect fluid with bulk viscosity and apply Eckart's and both the full and the truncated M\"uller-Israel-Stewart's theories as descriptions of the non-equilibrium processes. Our principal objective is to investigate if the dynamical properties of Dark Matter and Dark Energy can be described by a single viscous fluid and how such description changes when a causal theory (M\"uller-Israel-Stewart's, both in its full and truncated forms) is taken into account instead of Eckart's non-causal theory. To this purpose, we find numerical solutions for the gravitational potential and compare its behaviour with the corresponding LambdaCDM case. Eckart's and the full causal theory seem to be disfavoured, whereas the truncated theory leads to results similar to those of the LambdaCDM model for a bulk viscous speed in the interval 10^{-11} << c_b^2 < 10^{-8}. Tentatively relating such value to a square propagation velocity of the order of T/m of perturbations in a non-relativistic gas of particles with mass m at the epoch of matter-radiation equality, this may be compatible with a mass range 0.1 GeV < m << 100 GeV.Comment: 23 pages, 7 figure

    Effects of differential mobility on biased diffusion of two species

    Full text link
    Using simulations and a simple mean-field theory, we investigate jamming transitions in a two-species lattice gas under non-equilibrium steady-state conditions. The two types of particles diffuse with different mobilities on a square lattice, subject to an excluded volume constraint and biased in opposite directions. Varying filling fraction, differential mobility, and drive, we map out the phase diagram, identifying first order and continuous transitions between a free-flowing disordered and a spatially inhomogeneous jammed phase. Ordered structures are observed to drift, with a characteristic velocity, in the direction of the more mobile species.Comment: 15 pages, 4 figure

    Acceptability Assessment of a Locally Developed Onion Harvester Hand Tractor in La Union, Philippines

    Get PDF
    Onion farmers’ attitude toward a locally developed onion harvester in the Philippines has been unstudied due to the unavailability of the machine. Based on a respondent of 26 onion farmers, an acceptability assessment of the onion harvester was implemented. Data were gathered using questionnaires at two activities of actual hands-on operation and lectures and analyzed using fisher’s exact test. The ease of operation, cleaning and maintenance, safety of operation, ease of transport, technical field performance, adaptability, and investment viability were relevant attributes used in the acceptability of the onion harvester. The majority of the respondents positively accept the onion harvester. The user operation, cleaning and maintenance, ease of transport, adaptability, and investment viability are correlated positively to the willingness to buy or rent the machine. Conversely, user safety, technical performance, and aesthetics are not correlated with adoption. Since 38.5% of the farmers have no hand tractor, the preferred acquisition is renting the onion harvester

    Hemispherical power asymmetry: parameter estimation from CMB WMAP5 data

    Full text link
    We reexamine the evidence of the hemispherical power asymmetry, detected in the CMB WMAP data using a new method. At first, we analyze the hemispherical variance ratios and compare these with simulated distributions. Secondly, working within a previously-proposed CMB bipolar modulation model, we constrain model parameters: the amplitude and the orientation of the modulation field as a function of various multipole bins. Finally, we select three ranges of multipoles leading to the most anomalous signals, and we process corresponding 100 Gaussian, random field (GRF) simulations, treated as observational data, to further test the statistical significance and robustness of the hemispherical power asymmetry. For our analysis we use the Internally-Linearly-Coadded (ILC) full sky map, and KQ75 cut-sky V channel, foregrounds reduced map of the WMAP five year data (V5). We constrain the modulation parameters using a generic maximum a posteriori method. In particular, we find differences in hemispherical power distribution, which when described in terms of a model with bipolar modulation field, exclude the field amplitude value of the isotropic model A=0 at confidence level of ~99.5% (~99.4%) in the multipole range l=[7,19] (l=[7,79]) in the V5 data, and at the confidence level ~99.9% in the multipole range l=[7,39] in the ILC5 data, with the best fit (modal PDF) values in these particular multipole ranges of A=0.21 (A=0.21) and A=0.15 respectively. However, we also point out that similar or larger significances (in terms of rejecting the isotropic model), and large best-fit modulation amplitudes are obtained in GRF simulations as well, which reduces the overall significance of the CMB power asymmetry down to only about 94% (95%) in the V5 data, in the range l=[7,19] (l=[7,79]).Comment: 24 pages, 10 figures; few typos corrected; published in JCA
    • …
    corecore