Phantom Friedmann Cosmologies and Higher-Order Characteristics of Expansion

We discuss a more general class of phantom ($p < -\varrho$) cosmologies with various forms of both phantom ($w -1$) matter. We show that many types of evolution which include both Big-Bang and Big-Rip singularities are admitted and give explicit examples. Among some interesting models, there exist non-singular oscillating (or "bounce") cosmologies, which appear due to a competition between positive and negative pressure of variety of matter content. From the point of view of the current observations the most interesting cosmologies are the ones which start with a Big-Bang and terminate at a Big-Rip. A related consequence of having a possibility of two types of singularities is that there exists an unstable static universe approached by the two asymptotic models - one of them reaches Big-Bang, and another reaches Big-Rip. We also give explicit relations between density parameters $\Omega$ and the dynamical characteristics for these generalized phantom models, including higher-order observational characteristics such as jerk and "kerk". Finally, we discuss the observational quantities such as luminosity distance, angular diameter, and source counts, both in series expansion and explicitly, for phantom models. Our series expansion formulas for the luminosity distance and the apparent magnitude go as far as to the fourth-order in redshift $z$ term, which includes explicitly not only the jerk, but also the "kerk" (or "snap") which may serve as an indicator of the curvature of the universe.Comment: REVTEX 4, 23 pages, references updated, to appear in Annals of Physics (N.Y.

Acaricides resistance in ticks : selection, diagnosis, mechanisms, and mitigation

Ticks are blood-feeding ecto-parasites that have a cosmopolitan distribution in tropical and subtropical regions of the world. Ticks cause economic losses in the form of reduced blood, meat and dairy products, as well as pathogen transmission. Different acaricides such as organochlorines, organophosphates, formamidines (e.g. amitraz), synthetic pyrethroids, macrocyclic lactones, fipronil, and fluazuron are currently used sequentially or simultaneously to control tick infestations. Most acaricide treatments now face increasingly high chances of failure, due to the resistance selection in different tick populations against these drugs. Acaricide resistance in ticks can be developed in different ways, including amino acid substitutions that result in morphological changes in the acaricide target, metabolic detoxification, and reduced acaricide entry through the outer layer of the tick body. The current literature brings a plethora of information regarding the use of different acaricides for tick control, resistance selection, analysis of mutations in target sites, and resistance mitigation. Alternatives such as synergistic use of different acaricides, plant-derived phytochemicals, fungi as biological control agents, and anti-tick vaccines have been recommended to avoid and mitigate acaricide resistance. The purpose of this review was to summarize and discuss different acaricides applied for tick control, their mechanisms of action and resistance selection, genetic polymorphisms in their target molecules, as well as the approaches used for diagnosis and mitigation of acaricide resistance, specifically in Rhipicephalus microplus ticks

Weak Radiative Decays of Beauty Baryons

Weak radiative decays of beauty baryons into strange baryons, induced by the electroweak penguin, are estimated by using a quark model approach. Relations between formfactors in the semileptonic and in the weak radiative decays are derived within the heavy quark effective theory. The partial decay widths are found to be of the order of $10^{-15}{\rm MeV}$ for $\Lambda_b\rightarrow\Lambda\gamma$ and $\Xi_b\rightarrow\Xi\gamma$ and of the oder of $10^{-13}{\rm MeV}$ for $\Omega_b\rightarrow\Omega\gamma$. The $\Omega_b$ radiative decay is thus expected at the sizable branching ratio of approximately $10^{-4}$.Comment: 10 pages, latex, no figure

Automated Fact-Checking for Assisting Human Fact-Checkers

The reporting and analysis of current events around the globe has expanded from professional, editor-lead journalism all the way to citizen journalism. Politicians and other key players enjoy direct access to their audiences through social media, bypassing the filters of official cables or traditional media. However, the multiple advantages of free speech and direct communication are dimmed by the misuse of the media to spread inaccurate or misleading claims. These phenomena have led to the modern incarnation of the fact-checker -- a professional whose main aim is to examine claims using available evidence to assess their veracity. As in other text forensics tasks, the amount of information available makes the work of the fact-checker more difficult. With this in mind, starting from the perspective of the professional fact-checker, we survey the available intelligent technologies that can support the human expert in the different steps of her fact-checking endeavor. These include identifying claims worth fact-checking; detecting relevant previously fact-checked claims; retrieving relevant evidence to fact-check a claim; and actually verifying a claim. In each case, we pay attention to the challenges in future work and the potential impact on real-world fact-checking.Comment: fact-checking, fact-checkers, check-worthiness, detecting previously fact-checked claims, evidence retrieva

Effects of dilution and disorder on magnetism in diluted spin systems

The influence of configurational disorder on the magnetic properties of diluted Heisenberg spin systems is studied with regard to the ferromagnetic stability of diluted magnetic semiconductors. The equation of motion of the magnon Green's function is decoupled by Tyablikov approximation. With supercell approach, the concentrations of magnetic ions are determined by the size of the supercell in which there is only one magnetic ion per supercell in our method. In order to distinguish the influence of dilution and disorder, there are two kinds of supercells being used: the \textit{diluted and ordered} case and the \textit{diluted and disordered} case. The configurational averaging of magnon Green function due to disorder is treated in the augmented space formalism. The random exchange integrals between two supercells are treated as a matrix. The obtained magnon spectral densities are used to calculate the temperature dependence of magnetization and Curie temperature. The results are shown as following: (i) dilution leads to increasing the averaged distance of two magnetic ions, further decreases the effective exchange integrals and is main reason to reduce Curie temperature; (ii) spatial position disorder of magnetic ions results in the dispersions of the exchange integrals between two supercells and slightly changes ferromagnetic transition temperature; (iii) the exponential damping of distance dependence obviously reduces Curie temperature and should be set carefully in any phenomenological model.Comment: 8 pages, 3 figures, accepted by physica status solidi (b); added references and the corresponding remark

The Covariant Entropy Bound, Brane Cosmology, and the Null Energy Condition

In discussions of Bousso's Covariant Entropy Bound, the Null Energy Condition is always assumed, as a sufficient {\em but not necessary} condition which helps to ensure that the entropy on any lightsheet shall necessarily be finite. The spectacular failure of the Strong Energy Condition in cosmology has, however, led many astrophysicists and cosmologists to consider models of dark energy which violate {\em all} of the energy conditions, and indeed the current data do not completely rule out such models. The NEC also has a questionable status in brane cosmology: it is probably necessary to violate the NEC in the bulk in order to obtain a "self-tuning" theory of the cosmological constant. In order to investigate these proposals, we modify the Karch-Randall model by introducing NEC-violating matter into $AdS_5$ in such a way that the brane cosmological constant relaxes to zero. The entropy on lightsheets remains finite. However, we still find that the spacetime is fundamentally incompatible with the Covariant Entropy Bound machinery, in the sense that it fails the Bousso-Randall consistency condition. We argue that holography probably forbids all {\em cosmological} violations of the NEC, and that holography is in fact the fundamental physical principle underlying the cosmological version of the NEC.Comment: 21 pages, 3 figures, version 2:corrected and greatly improved discussion of the Bousso-Randall consistency check, references added; version3: more references added, JHEP versio

Photon Production from Nonequilibrium Disoriented Chiral Condensates in a Spherical Expansion

We study the production of photons through the non-equilibrium relaxation of a disoriented chiral condensate formed in the expanding hot central region in ultra-relativistic heavy-ion collisions. It is found that the expansion smoothes out the resonances in the process of parametric amplification such that the non-equilibrium photons are dominant to the thermal photons over the range 0.2-2 GeV. We propose that to search for non-equilibrium photons in the direct photon measurements of heavy-ion collisions can be a potential test of the formation of disoriented chiral condensates.Comment: 13 pages, 3 figure

Two-photon exclusive decays Bs→η(η′)γγB_s \to \eta (\eta') \gamma\gamma and B→KγγB \to K \gamma\gamma

The exclusive decay modes $B \to K \gamma\gamma$ and $B_s \to \eta (\eta') \gamma\gamma$ are shown to have significant branching ratios of approximately $0.5\times 10^{-7}$. This first calculation of these modes employs a model based on a cascade transition $B\to V\gamma\to P\gamma\gamma$ for estimating the long-distance contribution and the process $b\to s\gamma\gamma$ for the short distance one.Comment: 11 Page