Phase transitions in rotating neutron stars: Effects of stellar crusts

As a rapidly rotating neutron star spins down due to the loss of its angular momentum, its central density increases and the nuclear matter in its core converts to quark matter, which leads to a drastic decrease of the stellar moment of inertia, and even results in an era of spin-up of the pulsar (Glendenning, Pei, & Weber 1997). We find that given a certain equation of state in the liquid core, even if the backbending of the moment of inertia as a function of the rotating frequency occurs, an increase of the total moment of inertia by only 1% could carry adequate angular momentum and stop the star spin-up. This small discrepancy in the total moment of inertia might be due to the different properties of subnuclear matter in the crust, especially to different transition density and pressure at the inner boundary of the solid crust between various models. The strong dependence of the phenomenon of back-bending on the physical state of the crust provides, in principle, a new observational approach to check and constrain theories on subnuclear matter.published_or_final_versio

Neurodegenerative movement disorders: An epigenetics perspective and promise for the future

Neurodegenerative movement disorders (NMDs) are age dependent disorders that are characterised by the degeneration and loss of neurons, typically accompanied by pathological accumulation of different protein aggregates in the brain, which lead to motor symptoms. NMDs include Parkinson's disease, multiple system atrophy, progressive supranuclear palsy, and Huntington's disease, among others. Epigenetic modifications are responsible for functional gene regulation during development, adult life, and ageing, and have progressively been implicated in complex diseases such as cancer, and more recently in neurodegenerative diseases, such as NMDs. DNA methylation is by far the most widely studied epigenetic modification and consists of the reversible addition of a methyl group to the DNA without changing the DNA sequence. Although this research field is still in its infancy in relation to NMDs, an increasing number of studies point towards a role for DNA methylation in disease processes. This review addresses recent advances in epigenetic and epigenomic research in NMDs, with a focus on human brain DNA methylation studies. We discuss the current understanding of the DNA methylation changes underlying these disorders, the potential for use of these DNA modifications in peripheral tissues as biomarkers in early disease detection, classification, and progression as well as a promising role in future disease management and therapy

Low-energy, high-performance lossless 8×8 SOA switch

We demonstrate the first monolithically-integrated active-passive lossless 8×8 SOA switch. A wide IPDR of 14.5dB for penalty <1dB is achieved. The switch paths through the device exhibit excellent uniformity.The research leading to these results has received funding from the UK EPSRC through the INTERNET, STAR and COPOS II grants and the European Commission under FP7 grant agreement ICT 257210 PARADIGM.This is the accepted manuscript. The final version is available from OSA at http://www.opticsinfobase.org/abstract.cfm?uri=OFC-2015-Th4E.6

Provision of reinforcement in concrete solids using the generalized genetic algorithm

A generalized genetic algorithm has been developed to find the global optimal reinforcement contents for a concrete solid structure subjected to a general three-dimensional (3D) stress field. Feasible solutions were examined based on the genetic algorithm, and the heterogeneous strategy used ensures that all of the local optimal regions are searched and the most optimal reinforcement content found. The effectiveness of the proposed approach has been validated by comparing the steel contents evaluated using the present method with those obtained from other available methods. A more economic design is achieved by the proposed algorithm. The method developed provides the designer with a valuable tool for the determination of reinforcements in complicated solid concrete structures. © 2011 American Society of Civil Engineers.postprin

Demonstration of the feasibility of large-port-count optical switching using a hybrid Mach-Zehnder interferometer-semiconductor optical amplifier switch module in a recirculating loop.

For what we believe is the first time, the feasibility of large-port-count nanosecond-reconfiguration-time optical switches is demonstrated using a hybrid approach, where Mach-Zehnder interferometric (MZI) switches provide low-loss, high-speed routing with short semiconductor optical amplifiers (SOAs) being integrated to enhance extinction. By repeatedly passing signals through a monolithic hybrid dilated 2×2 switch module in a recirculating loop, the potential performance of high-port-count switches using the hybrid approach is demonstrated. Experimentally, a single pass switch penalty of only 0.1 dB is demonstrated for the 2×2 module, while even after seven passes through the switch, equivalent to a 128×128 router, a penalty of only 2.4 dB is recorded at a data rate of 10 Gb/s.This is the author accepted manuscript. The final version is published in Optics Letters - http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-39-18-5244

One Loop Renormalization of the Littlest Higgs Model

In Little Higgs models a collective symmetry prevents the Higgs from acquiring a quadratically divergent mass at one loop. This collective symmetry is broken by weakly gauged interactions. Terms, like Yukawa couplings, that display collective symmetry in the bare Lagrangian are generically renormalized into a sum of terms that do not respect the collective symmetry except possibly at one renormalization point where the couplings are related so that the symmetry is restored. We study here the one loop renormalization of a prototypical example, the Littlest Higgs Model. Some features of the renormalization of this model are novel, unfamiliar form similar chiral Lagrangian studies.Comment: 23 pages, 17 eps figure

High Performance 400 Gigabit Ethernet Links using Hybrid Multiband CAP/QAM Scheme

We propose the first combined 4×100Gb/s hybrid multiband CAP-16 transmitter and QAM-16 receiver system and simulations show that it has 0.7 dBo (2.2 dBo) more power margin than 8×50Gb/s (4×100Gb/s) PAM-4 over DML (EML) SMF link.This work was partly supported by the European Union under a Marie Curie Intra-European Fellowship for Career Development (CEEOALAN project) and by the UK EPSRC via the INTERNET project.This is the accepted manuscript. The final version is available at https://www.osapublishing.org/abstract.cfm?uri=OFC-2015-Th2A.65

General radiation formulae for a relativistic charged particle moving in curved magnetic field lines: The synchrocurvature radiation mechanism

We calculate the radiation spectrum, characteristic frequency, and power emitted by a relativistic charged particle moving in curved magnetic field lines with arbitrary pitch angle, which can be approximated by a curved spiral trajectory. We obtain some universal formulae which can be identical to either synchrotron radiation or curvature radiation in certain parametric regions, but in general the radiation features of this new mechanism can significantly differ from those of these two known mechanisms. Since magnetic field lines are generally curved in many real systems (e.g., a pulsar magnetosphere), this new mechanism can more realistically describe the radiation from relativistic charged particles in these systems. We also find that the degree of polarization is the best quantity to differentiate this new mechanism from the other two mechanisms. © 1996. The American Astronomical Society. All rights reserved.published_or_final_versio

Warped Radion Dark Matter

Warped scenarios offer an appealing solution to the hierarchy problem. We consider a non-trivial deformation of the basic Randall-Sundrum framework that has a KK-parity symmetry. This leads to a stable particle beyond the Standard Model, that is generically expected to be the first KK-parity odd excitation of the radion field. We consider the viability of the KK-radion as a DM candidate in the context of thermal and non-thermal production in the early universe. In the thermal case, the KK-radion can account for the observed DM density when the radion decay constant is in the natural multi-TeV range. We also explore the effects of coannihilations with the first KK excitation of the RH top, as well as the effects of radion-Higgs mixing, which imply mixing between the KK-radion and a KK-Higgs (both being KK-parity odd). The non-thermal scenario, with a high radion decay constant, can also lead to a viable scenario provided the reheat temperature and the radion decay constant take appropriate values, although the reheat temperature should not be much higher than the TeV scale. Direct detection is found to be feasible if the DM has a small (KK-parity odd) Higgs admixture. Indirect detection via a photon signal from the galactic center is an interesting possibility, while the positron and neutrino fluxes from KK-radion annihilations are expected to be rather small. Colliders can probe characteristic aspects of the DM sector of warped scenarios with KK-parity, such as the degeneracy between the radion and the KK-radion (DM) modes.Comment: 43 pages, 16 figures; added reference