Empirical Mantissa Distributions of Pulsars

The occurrence of digits one through nine as the leftmost nonzero digit of numbers from real world sources is often not uniformly distributed, but instead, is distributed according to a logarithmic law, known as Benford's law. Here, we investigate systematically the mantissa distributions of some pulsar quantities, and find that for most quantities their first digits conform to this law. However, the barycentric period shows significant deviation from the usual distribution, but satisfies a generalized Benford's law roughly. Therefore pulsars can serve as an ideal assemblage to study the first digit distributions of real world data, and the observations can be used to constrain theoretical models of pulsar behavior.Comment: 15 pages, 7 figures, final version in journal publicatio

Lorentz violation induced vacuum birefringence and its astrophysical consequences

In the electromagnetism of loop quantum gravity, two helicities of a photon have different phase velocities and group velocities, termed as "vacuum birefringence". Two novel phenomenons, "peak doubling" and "de-polarization", are expected to appear for a linearly polarized light from astrophysical sources. We show that the criteria to observe these two phenomenons are the same. Further, from recently observed $\gamma$-ray polarization from Cygnus X-1, we obtain an upper limit $\sim 8.7\times10^{-12}$ for Lorentz-violating parameter $\chi$, which is the most firm constraint from well-known systems. We also suggest to analyze possible existence of "peak doubling" through Fermi LAT GRBs.Comment: 4 latex pages, 2 figures, short version for publication in PRD. For a detailed long version, please look at the first version of this arXiv paperarXiv:1104.4438v

Lorentz violation effects on astrophysical propagation of very high energy photons

Lorentz violation (LV) is predicted by some quantum gravity (QG) candidates, wherein the canonical energy-momentum dispersion relation, $E^2=p^2+m^2$, is modified. Consequently, new phenomenons beyond the standard model are predicted. Especially, the presence of LV highly affects the propagation of astrophysical photons with very high energies from distant galaxies. In this paper, we review the updating theoretical and experimental results on this topic. We classify the effects into three categories: (i) time lags between photons with different energies; (ii) a cutoff of photon flux above the threshold energy of photon decay, $\gamma \rightarrow e^++e^-$; (iii) new patterns in the spectra of multi-TeV photons and EeV photons, due to the absorption of background lights. As we can see, the details of LV effects on astrophysical photons depend heavily on the "phase space" of LV parameters. From observational aspects, nowadays available and upcoming instruments can study these phenomenons hopefully, and shed light onto LV issues and QG theories. The most recent progresses and constraints on the ultra-high energy cosmic rays (UHECRs) are also fully discussed.Comment: 9 pages, 1 figure, final version for publication in MPLA as a review articl

Gender differences in cognitive dissonance reduction strategies for partner\u27s physical attractiveness

Physical attractiveness is an important standard for mate selection for both men and women (Langlois et al., 2000). However, men may care more about their partners’ physical attractiveness than do women (Feingold, 1990). This study applied cognitive dissonance theory (Festinger, 1957) to physical attractiveness in mate selection. Not everyone can find a partner who is as attractive as he or she would ideally like, so this may create cognitive dissonance between their attitudes and behavior. Cognitive dissonance theory suggests that people try to reduce uncomfortable feelings caused by the differences between their attitudes and behaviors (Festinger, 1957). Because men care more about their partners’ physical attractiveness than do women, men and women may reduce cognitive dissonance caused by partner’s physical attractiveness differently. 282 college students who were in a heterosexual romantic relationship completed demographic questions and rated their partner’s physical attractiveness. Then they were randomly assigned to a physical attractiveness condition, a personality condition, or a pure control condition. Participants in the physical attractiveness condition were primed to think of physical attractiveness as important, but reminded of their partner’s lower attractiveness levels; participants in the personality condition were primed to think of kindness as important and not reminded about their partner’s attractiveness level; and participants in the pure control condition were primed to think about healthy foods. Then all participants rated their partner’s physical attractiveness again and the importance of physical attractiveness in relationships. They also completed the measures assessing the quality of alternatives and commitment level in their current relationships. I hypothesized that men would be more likely to change attitudes toward finding a new partner or leaving their current partner if they believe their partners’ physical attractiveness is important but they are reminded that they are dating less attractive partners. Specifically, I predicted that men in the physical attractiveness condition would score higher on quality of alternatives and lower on level of commitment in relationships compared to women in physical attractiveness condition. In contrast, I expected that women would be more likely to change attitudes toward partners’ physical attractiveness in this situation. Specifically, I predicted that women in the physical attractiveness condition would score lower on importance of partner’s physical attractiveness and higher on ratings of partner’s attractiveness. I did not expect gender differences in the other two conditions. Contrary to predictions, men and women did not differ in ways of reducing dissonance. Men rated physical attractiveness as more important, reported more relationship alternatives, and were less committed to their current relationships than were women. Men also tended to rate their partner as more attractive than women did. There were no effects of condition. It may be that short-term interactions are not sufficient to induce dissonance about relationship issues with their partners

Eikonal equation of the Lorentz-violating Maxwell theory

We derive the eikonal equation of light wavefront in the presence of Lorentz invariance violation (LIV) from the photon sector of the standard model extension (SME). The results obtained from the equations of $\mathbf{E}$ and $\mathbf{B}$ fields respectively are the same. This guarantees the self-consistency of our derivation. We adopt a simple case with only one non-zero LIV parameter as an illustration, from which we find two points. One is that, in analogy with Hamilton-Jacobi equation, from the eikonal equation, we can derive dispersion relations which are compatible with results obtained from other approaches. The other is that, the wavefront velocity is the same as the group velocity, as well as the energy flow velocity. If further we define the signal velocity $v_s$ as the front velocity, there always exists a mode with $v_s>1$, hence causality is violated classically. Thus our method might be useful in the analysis of Lorentz violation in QED in terms of classical causality .Comment: 14 latex pages, no figure, final version for publication in EPJ

Bounding the mass of graviton in a dynamic regime with binary pulsars

In Einstein's general relativity, gravity is mediated by a massless spin-2 metric field, and its extension to include a mass for the graviton has profound implication for gravitation and cosmology. In 2002, Finn and Sutton used the gravitational-wave (GW) back-reaction in binary pulsars, and provided the first bound on the mass of graviton. Here we provide an improved analysis using 9 well-timed binary pulsars with a phenomenological treatment. First, individual mass bounds from each pulsar are obtained in the frequentist approach with the help of an ordering principle. The best upper limit on the graviton mass, $m_{g}<3.5\times10^{-20} \, {\rm eV}/c^{2}$ (90% C.L.), comes from the Hulse-Taylor pulsar PSR B1913+16. Then, we combine individual pulsars using the Bayesian theorem, and get $m_{g}<5.2\times10^{-21} \, {\rm eV}/c^{2}$ (90% C.L.) with a uniform prior for $\ln m_g$. This limit improves the Finn-Sutton limit by a factor of more than 10. Though it is not as tight as those from GWs and the Solar System, it provides an independent and complementary bound from a dynamic regime.Comment: 8 pages, 2 figures; accepted by PR

Lorentz violation from cosmological objects with very high energy photon emissions

Lorentz violation (LV) is predicted by some quantum gravity theories, where photon dispersion relation is modified, and the speed of light becomes energy-dependent. Consequently, it results in a tiny time delay between high energy photons and low energy ones. Very high energy (VHE) photon emissions from cosmological distance can amplify these tiny LV effects into observable quantities. Here we analyze four VHE $\gamma$-ray bursts (GRBs) from Fermi observations, and briefly review the constraints from three TeV flares of active galactic nuclei (AGNs) as well. One step further, we present a first robust analysis of VHE GRBs taking the intrinsic time lag caused by sources into account, and give an estimate to quantum gravity energy $\sim 2 \times 10^{17}$ GeV for linear energy dependence, and $\sim 5 \times 10^9$ GeV for quadratic dependence. However, the statistics is not sufficient due to the lack of data, and further observational results are desired to constrain LV effects better.Comment: 14 pages, 2 figures, final version to appear in Astroparticle Physic

Sea quark contents of octet baryons

The flavor asymmetry of the nucleon sea, i.e., the excess of $d\bar{d}$ quark-antiquark pairs over $u\bar{u}$ ones in the proton can be explained by several different models; therefore, it is a challenge to discriminate these models from each other. We examine in this Letter three models: the balance model, the meson cloud model, and the chiral quark model, and we show that these models give quite different predictions on the sea quark contents of other octet baryons. New experiments aimed at measuring the flavor contents of other octet baryons are needed for a more profound understanding of the non-perturbative properties of quantum chromodynamics (QCD).Comment: 15 pages, 2 figures, version in final publicatio

Applications of Functionalized Fullerenes in Tumor Theranostics

Functionalized fullerenes with specific physicochemical properties have been developed for cancer diagnosis and therapy. Notably, metallofullerene is a new class of magnetic resonance imaging (MRI) contrast-enhancing agent, and may have promising applications for clinical diagnosis. Polyhydroxylated and carboxyl fullerenes have been applied to photoacoustic imaging. Moreover, in recent years, functionalized fullerenes have shown potential in tumor therapies, such as photodynamic therapy, photothermal treatment, radiotherapy and chemotherapeutics. Their antitumor effects may be associated with the modulation of oxidative stress, anti-angiogenesis, and immunostimulatory activity. While various types of novel nanoparticle agents have been exploited in tumor theranostics, their distribution, metabolism and toxicity in organisms have also been a source of concern among researchers. The present review summarizes the potential of fullerenes as tumor theranostics agents and their possible underlying mechanisms are discussed