HI scaling relations of galaxies in the environment of HI-rich and control galaxies observed by the Bluedisk project

Our work is based on the "Bluedisk" project, a program to map the neutral gas in a sample of 25 HI-rich spirals and a similar number of control galaxies with the Westerbork Synthesis Radio Telescope (WSRT). In this paper we focus on the HI properties of the galaxies in the environment of our targeted galaxies. In total, we extract 65 galaxies from the WSRT cubes with stellar masses between $10^8M_{\odot}$ and $10^{11}M_{\odot}$. Most of these galaxies are located on the same HI mass-size relation and "HI-plane" as normal spiral galaxies. We find that companions around HI-rich galaxies tend to be HI-rich as well and to have larger R90,HI/R50,HI. This suggests a scenario of "HI conformity", similar to the colour conformity found by Weinmann et al. (2006): galaxies tend to adopt the HI properties of their neighbours. We visually inspect the outliers from the HI mass-size relation and galaxies which are offset from the HI plane and find that they show morphological and kinematical signatures of recent interactions with their environment. We speculate that these outliers have been disturbed by tidal or ram-pressure stripping processes, or in a few cases, by accretion events.Comment: 16 pages, 12 figures; accepted for publication in MNRA

Explorations of the Top Quark Forward-Backward Asymmetry at the Tevatron

We consider the recent measurement of the top quark forward-backward asymmetry at the Fermilab Tevatron, which shows a discrepancy of slightly more than 2$\sigma$ compared to the SM prediction. We find that $t$-channel exchange of a color sextet or triplet scalar particle can explain the measurement, while leaving the cross section for $t \bar{t}$ production within measured uncertainties. Such particles have good discovery prospects by study of the kinematic structure of $t \bar{t}$+jets at the LHC.Comment: 14 pages, 10 figures, 1 tabl

Influence of Fermion Velocity Renormalization on Dynamical Mass Generation in QED3_3

We study dynamical fermion mass generation in (2+1)-dimensional quantum electrodynamics with a gauge field coupling to massless Dirac fermions and non-relativistic scalar bosons. We calculate the fermion velocity renormalization and then examine its influence on dynamical mass generation by using the Dyson-Schwinger equation. It is found that dynamical mass generation takes place even after including the scalar bosons as long as the bosonic compressibility parameter $\xi$ is sufficiently small. In addition, the fermion velocity renormalization enhances the dynamically generated mass.Comment: 6 pages, 3 figures, Chinese Physics Letter, Vol 29, page 057401(2012

A Multi-cell MMSE Precoder for Massive MIMO Systems and New Large System Analysis

In this paper, a new multi-cell MMSE precoder is proposed for massive MIMO systems. We consider a multi-cell network where each cell has $K$ users and $B$ orthogonal pilot sequences are available, with $B = \beta K$ and $\beta \ge 1$ being the pilot reuse factor over the network. In comparison with conventional single-cell precoding which only uses the $K$ intra-cell channel estimates, the proposed multi-cell MMSE precoder utilizes all $B$ channel directions that can be estimated locally at a base station, so that the transmission is designed spatially to suppress both parts of the inter-cell and intra-cell interference. To evaluate the performance, a large-scale approximation of the downlink SINR for the proposed multi-cell MMSE precoder is derived and the approximation is tight in the large-system limit. Power control for the pilot and payload, imperfect channel estimation and arbitrary pilot allocation are accounted for in our precoder. Numerical results show that the proposed multi-cell MMSE precoder achieves a significant sum spectral efficiency gain over the classical single-cell MMSE precoder and the gain increases as $K$ or $\beta$ grows. Compared with the recent M-ZF precoder, whose performance degrades drastically for a large $K$, our M-MMSE can always guarantee a high and stable performance. Moreover, the large-scale approximation is easy to compute and shown to be accurate even for small system dimensions.Comment: 6 pages, 4 figures, accepted by Globecom 2015. arXiv admin note: text overlap with arXiv:1509.0175

Bolstering cholesteryl ester hydrolysis in liver: A hepatocyte-targeting gene delivery strategy for potential alleviation of atherosclerosis

Current atherosclerosis treatment strategies primarily focus on limiting further cholesteryl esters (CE) accumulation by reducing endogenous synthesis of cholesterol in the liver. No therapy is currently available to enhance the removal of CE, a crucial step to reduce the burden of the existing disease. Given the central role of hepatic cholesteryl ester hydrolase (CEH) in the intrahepatic hydrolysis of CE and subsequent removal of the resulting free cholesterol (FC), in this work, we applied galactosefunctionalized polyamidoamine (PAMAM) dendrimer generation 5 (Gal-G5) for hepatocyte-specific delivery of CEH expression vector. The data presented herein show the increased specific uptake of Gal-G5/CEH expression vector complexes (simply Gal-G5/CEH) by hepatocytes in vitro and in vivo. Furthermore, the upregulated CEH expression in the hepatocytes significantly enhanced the intracellular hydrolysis of high density lipoprotein-associated CE (HDL-CE) and subsequent conversion/secretion of hydrolyzed FC as bile acids (BA). The increased CEH expression in the liver significantly increased the flux of HDL-CE to biliary as well as fecal FC and BA. Meanwhile, Gal-G5 did not induce hepatic or renal toxicity. It was also not immunotoxic. Because of these encouraging pre-clinical testing results, using this safe and highly efficient hepatocyte-specific gene delivery platform to enhance the hepatic processes involved in cholesterol elimination is a promising strategy for the alleviation of atherosclerosis

Absence of dynamical gap generation in suspended graphene

There is an interesting proposal that the long-range Coulomb interaction in suspended graphene can generate a dynamical gap, which leads to a semimetal-insulator phase transition. We revisit this problem by solving the self-consistent Dyson-Schwinger equations of wave function renormalization and fermion gap. In order to satisfy the Ward identity, a suitable vertex function is introduced. The impacts of singular velocity renormalization and dynamical screening on gap generation are both included in this formalism, and prove to be very important. We obtain a critical interaction strength, $3.2 < \alpha_{c} < 3.3$, which is larger than the physical value $\alpha = 2.16$ for suspended graphene. It therefore turns out that suspended graphene is a semimetal, rather than insulator, at zero temperature.Comment: 14 pages, 5 figures, 1 tabl

Fate of non-Fermi liquid behavior in QED3_{3} at finite chemical potential

The damping rate of two-dimensional massless Dirac fermions exhibit non-Fermi liquid behavior, $\propto \epsilon^{1/2}$, due to gauge field at zero temperature and zero chemical potential. We study the fate of this behavior at finite chemical potential. We fist calculate explicitly the temporal and spatial components of vacuum polarization functions. The analytical expressions imply that the temporal component of gauge field develops a static screening length at finite chemical potential while the transverse component remains long-ranged owing to gauge invariance. We then calculate the fermion damping rate and show that the temporal gauge field leads to normal Fermi liquid behavior but the transverse gauge field leads to non-Fermi liquid behavior $\propto \epsilon^{2/3}$ at zero temperature. This energy-dependence is more regular than $\propto \epsilon^{1/2}$ and does not change as chemical potential varies.Comment: 12 pages, 1 figur