bluuebunny/crossref_metadata_2025_split huggingface dataset:
Birth accelerations of neutron stars
Authors: Heras Ricardo 
Published: March 2013

AbstractWe suggest that neutron stars experienced at birth three related physical changes, which may originate in magneto-rotational instabilities: (i) an increase in period from the initial value P0 to the current value Ps, implying a change of rotational energy Δ Erot; (ii) an exponential decay of its magnetic field from the initial value B0 to the current surface value Bs, implying a change of radiative energy Δ Erad; and (iii) an increase of space velocity from the initial value v0 to the current value v, implying a change of kinetic energy Δ Ekin. These changes are assumed to be connected by Δ Erad + Δ Ekin = Δ Erot. This means that the radiation loss and increase of kinetic energy are both at the expense of a rotational energy loss. It is shown that this energy conversion occurs during times of order of 10−4 s if the neutron stars are born with magnetic fields in the range of 1015–1016 G and initial periods in range 1–20 ms. It is shown that the birth accelerations of neutron stars are of the order of 108g.
Neutron stars: history of the magnetic field decay
Authors: Igoshev Andrei P. , Kholtygin Alexander F. 
Published: March 2013

AbstractUsing the data of the ATNF pulsar catalog we study the relation connected the real age t of young neutron stars (NS) and their spin-down age τ. We suppose that this relation is independent from both initial period of the NS and its initial surface magnetic field, and that the laws of the surface magnetic field decay are similar for all NSs in the Milky Way. We further assume that the birth-rate of pulsars was constant during at least last 200 million years. With these assumptions we were able to restore the history of the magnetic field decay for the galactic NSs. We reconstruct the universal function f(t) = B(t)/B0, where B0 is the initial magnetic field and B(t) is the magnetic field of NS at the age t. The function f(t) can be fitted by a power law with power index α = −1.17.
Testing the relationship between nulling, drifting and mode-changing
Authors: Joshi Bhal Chandra 
Published: March 2013

AbstractRecent observations, suggesting that subpulse drifting, pulse nulling and profile mode-changes are related phenomena, are reviewed and it is argued that these are associated with global changes in the magnetosphere. Long simultaneous multi-frequency observations are useful to test this premise as is illustrated by the preliminary results from a recent study of PSR B0031–07, B0809+74 and B2319+60. Such observations for a larger sample of pulsars will be useful to constrain recent models, invoking global changes in the pulsar magnetosphere, proposed to explain observations demonstrating association of spin-down changes with profile mode-changes.
Gamma-ray emission from pulsar binaries
Authors: Kirk John , Mochol Iwona 
Published: March 2013

AbstractPulsar winds, containing charged particles, waves and a net (phase-averaged) magnetic field, are thought to fuel the high-energy emission from several gamma-ray binaries. They terminate where the ram pressure matches that of the surroundings - which, in binaries, is provided by the wind of the companion. Before termination, pulsed emission can be produced by inverse Compton scattering of photons from the companion by particles in the waves. After termination, both the bulk kinetic energy of the particles and the Poynting flux in the waves are dissipated into an energetic particle population embedded in the surviving phase-averaged magnetic field. Pulsed emission is no longer possible, but a substantial flux of unpulsed high-energy photons can be produced. I will present results showing that the physical conditions at the termination shock can be divided into two regimes: a high density one, where current sheets in the wind are first compressed by an MHD shock and subsequently dissipate by reconnection, and a low density one, where the wind can first convert into an electromagnetic wave in the shock precursor, which then damps and merges into the wind nebula. The shocks surrounding isolated pulsars fall into the low-density category, but those around pulsars in binary systems, may transit from one regime to the other according to binary phase. The implications of the shock-structure dichotomy for these objects will be discussed.
TeV cosmic-ray electrons from millisecond pulsars
Authors: Kisaka Shota , Kawanaka Norita 
Published: March 2013

AbstractRecent γ-ray observations by the Fermi Gamma-Ray Space Telescope suggest that the γ-ray millisecond pulsar (MSP) population is separated into two subclasses with respect to pair multiplicity. Here, we calculate the cosmic-ray electron/positron spectra from MSPs. Based on the assumption of equipartition in the pulsar-wind region, the typical energy of electrons/positrons ejected by an MSP with pair multiplicity of the order of unity is ~50 TeV. In this case, we find that a large peak in the 10-50 TeV energy range would be observed in the cosmic-ray electron/positron spectrum. Even if the fraction of pair-starved MSPs is 10%, a large peak would be detectable with future missions such as CALET and CTA.
A pulsar census of the Local Group
Authors: Kondratiev Vladislav , Lorimer Duncan , McLaughlin Maura , Ransom Scott 
Published: March 2013

AbstractWe carried out a search for pulsars in nearby galaxies with the GBT and Arecibo radio telescopes at 820 and 327 MHz, correspondingly. Currently, the Magellanic Clouds are the only galaxies except for Milky Way known to harbor radio pulsars, with a total of 20 pulsars being discovered there to date. Discovery of pulsars in other galaxies can be used to trace the history of massive star formation and would allow to probe the intermediate intergalactic medium. We selected 22 galaxies of the Local Group at high galactic latitudes, |b| > 26 deg, with most of them being dwarf spheroidals with old star population. This makes them promising targets to search for giant pulses from recycled millisecond pulsars. Both single-pulse and periodicity searches were performed for trial dispersion measures up to 1000. No extragalactic pulsars are found in half of the selected targets processed so far. I will give the overview of our targetted searches, present potential candidates and discuss the obtained results.
H-cluster stars
Authors: Lai X. Y. , Xu R. X. 
Published: March 2013

AbstractThe study of dense matter at ultra-high density has a very long history, which is meaningful for us to understand not only cosmic events in extreme circumstances but also fundamental laws of physics. In compact stars at only a few nuclear densities but low temperature, quarks could be interacting strongly with each other. That might produce quarks grouped in clusters, although the hypothetical quark-clusters in cold dense matter have not been confirmed due to the lack of both theoretical and experimental evidence. A so-called H-cluster matter is proposed in this paper as the nature of dense matter in reality.Motivated by recent lattice QCD simulations of the H-dibaryons (with structure uuddss), we are therefore considering here a possible kind of quark-clusters, H-clusters, that could emerge inside compact stars during their initial cooling, as the dominant components inside (the degree of freedom could then be H-clusters there). We study the stars composed of H-clusters, i.e., H-cluster stars, and derive the dependence of their maximum mass on the in-medium stiffening effect, showing that the maximum mass could be well above 2 M⊙ as observed and that the resultant mass-radius relation fits the measurement of the rapid burster under reasonable parameters. Besides a general understanding of different manifestations of compact stars, we expect further observational and experimental tests for the H-cluster stars in the future.
Profile stability and timing precision limit of millisecond pulsars
Authors: Liu Kuo 
Published: March 2013

AbstractMillisecond pulsars are shown to have highly regular rotations and stable profiles, which enables the utilisation of them as accurate clocks. In this talk, I will present the latest studies on profile stability of several millisecond pulsars. I will focus on single pulse stability and its influence on the shape and phase of integrated profiles achieved on short timescales. It will be shown that the single pulse instability seems to be a source dependent issue, and they would influence differently on timing precision of the pulsar. The understanding of profile stability is essential in determining the timing precision limit and the optimal timing scheme with the future radio telescopes.
X-ray properties of G308.3-1.4 and its central compact object
Authors: Seo K. A. , Hui C. Y. , Huang R. H. H. , Trepl L. , Lu T.-N. , Kong A. K. H. , Walter F. M. 
Published: March 2013

AbstractWe present a short Chandra observation that confirms a previous unidentified extended X-ray source, G308.3-1.4, as a new supernova remnant (SNR) in the Milky Way. Apart from identifying its SNR nature, a bright X-ray point source has also been discovered at the geometrical center. Its X-ray spectral properties are similar to those of a particular class of neutron star known as central compact objects (CCOs). On the other hand, the optical properties of this counterpart suggests it to be a late-type star. Together with the interesting ~ 1.4 hours X-ray periodicity found by Chandra, this system can possibly provide the first direct evidence of a compact binary survived in a supernova explosion.
Formation of Binary and Millisecond Pulsars: Puzzles and Possible Solutions
Authors: Shao Yong , Li Xiang-Dong 
Published: March 2013

AbstractWe present a systematic study of the evolution of intermediate- and low-mass X-ray binaries. Our calculations suggest that millisecond binary pulsars in wide orbits might have neutron stars born massive, or been formed through mass transfer driven by planet/brown dwarf-involved common envelope evolution.
On the glitch evolution of pulsars
Authors: Urama J. O. , Joshi B. C. , Chukwude A. E. 
Published: March 2013

AbstractObservation of pulsar glitches remains a powerful tool for studying the interior of neutron stars. Many of the observed glitch properties are shown to result from the evolution of glitches in the different manifestations of neutron stars. Specifically, the type of glitches associated with the Crab and Vela pulsars are explained by this model. We are, also, able to adequately account for the absence, or very low rate, of glitches among the youngest and the very old pulsars.
On the mode switching timescales of pulsar PSR B0329+54
Authors: Wang Hong-Guang , Chen Jian-Ling , Wen Zhi-Gang , Pi Fei-Peng 
Published: March 2013

AbstractChen et al. (2011) found that the durations (timescales) of the normal and abnormal modes of PSR B0329+54 follow a gamma distribution, and constrained the parameters of the distribution function. In this paper, we perform a further analysis on the relationship between the timescales of the two modes. The ratio between the durations of a normal mode and the succeeding abnormal mode is calculated for 54 such pairs. It is found that the cumulative distribution function (CDF) of the ratio is consistent with the CDF obtained by assuming random mode switching, suggesting that the two modes work independently.
Pulsed γ-ray emission from magnetar 1E 2259+586
Authors: Wu J. H. K. , Hui C. Y. , Huang R. H. H. , Kong A. K. H. , Cheng K. S. , Takata J. , Tam P. H. T. , Wu E. M. H. , Liu C.-Y. 
Published: March 2013

AbstractAnomalous X-ray pulsars (AXPs) are thought to be magnetars which are young isolated neutron stars with extremely strong magnetic fields of >1014 Gauss. Their tremendous magnetic fields inferred from the spin parameters provide a huge energy reservoir to power the observed X-ray emission. High-energy emission above 0.3 MeV has never been detected despite intensive search. Here, we present the possible Fermi Large Area Telescope (LAT) detection of γ-ray pulsations above 200 MeV from the AXP, 1E 2259+586, which puts the current theoretical models of γ-ray emission mechanisms of magnetars into challenge. We speculate that the high-energy γ-rays originate from the outer magnetosphere of the magnetar.
Rotation Measure variations for millisecond pulsars
Authors: Yan Wenming , Manchester R. N. , Wang Na 
Published: March 2013

AbstractAs part of the Parkes Pulsar Timing Array (PPTA) project, frequent observations of 20 millisecond pulsars are made using the Parkes 64-m radio telescope. Variations in the mean position angle of the 20 millisecond pulsars can be studied by the PPTA data being recorded in full-polarization mode. We briefly discuss these results.
Association of Prescription Drug Misuse with Risky Motor Vehicle Behaviors among Low-Income Young Women
Authors: Laz Tabassum H. , Shemontee Mirza O. , Rahman Mahbubur , Berenson Abbey B. 
Published: March 2013

Background The purpose of this study was to examine the association between prescription drug misuse and risky motor vehicle behaviors among 16–24-year-old women. Methods A survey was conducted on misuse of 4 classes of prescription drugs (pain relievers, tranquilizers, stimulants, and sedatives) and past-month risky motor vehicle behaviors among these women during 2008–2010. Results Overall, 47.7% (1408/2952) of women reported risky motor vehicle behavior(s) in the past month. Misuse of 1 or more of the 4 classes was 30.1% (lifetime), 15.0% (past year), and 6.7% (past month). Misuse of 1 or more of these prescription drug classes was associated with risky motor vehicle behaviors in their lifetime (odds ratio [OR]: 1.83, 95% confidence interval [CI]: 1.54–2.18), past year (OR: 2.25, 95% CI: 1.80–2.83), and past month (OR: 2.70, 95% CI: 1.94–3.78). Conclusions The current finding that misuse of 1 or more of the 4 prescription drug classes, irrespective of when this last occurred, is associated with risky motor vehicle behaviors may help formulate awareness programs.
Necrosis of the Intranasal Structures and Soft Palate as a Result of Heroin Snorting: A Case Series
Authors: Peyrière Hélène , Léglise Yves , Rousseau Arnaud , Cartier Cesar , Gibaja Valérie , Galland Pascal 
Published: March 2013

Background The link between nasal inhalation of cocaine and nasal and palatal necrosis is well documented. In contrast, few data are available concerning nasal mucosa necrosis related to heroin snorting. The authors report here the retrospective analysis of 24 cases of orofacial lesions in patients with nasal heroin usage, collected between 2006 and 2012. Cases The cases concern 17 males and 7 females (median age 29.5 (range: 24–42)) with chronic consumption of intranasal heroin (from 2 months to more than 10 years). Six patients had a history of cocaine abuse. The median daily amount of heroin consumption was 5 g (range: 0.5–10). The complications were nasal perforation (11 cases), nasal ulceration or erythema (5 cases), nasal septum necrosis (5 cases), pharyngeal ulceration (3 cases), and palate damages (5 cases). The most common clinical signs and symptoms were nasal pain, purulent sputum, dysphagia, and rhinitis. Maintenance therapy with methadone (19 cases) or buprenorphine (3 cases) was initiated. In 8 cases, the injury improved. Discussion The potential of heroin to induce destructive orofacial lesions should be considered when nasal damages are observed in patients with drug abuse. A multidisciplinary approach seems to be the most effective means of managing such patients.
Why Would Khat Chewers Quit? An In-Depth, Qualitative Study on Saudi Khat Quitters
Authors: Alsanusy Rashad , El-Setouhy Maged 
Published: March 2013

Background Khat chewing, which has many adverse health and social consequences, is highly prevalent and socially accepted in the Jazan region of the Kingdom of Saudi Arabia. Methods A qualitative study was conducted with 47 adult male former khat users regarding their khat initiation, continuance, and cessation, the amounts of khat they had used, and the health and social consequences of their use and cessation of use. Results Participants noted a desire to show maturity, ease of availability of khat, and peer pressure as reasons for initiating khat chewing. Many noted long leisure times with little to do as a reason for continuing use. Negative consequences of khat use were seen in economic, health, familial, and sexual areas of their lives. After quitting khat use, participants saw improvements in all of these areas. Conclusions A comprehensive community development program (CCDP) tackling, among other issues, the normalization of khat use, substantial leisure times with few positive activities, and misinformation about the “benefits” of khat use, as well as developing peer and family training programs to help prevent or stop khat use, would be useful to reduce khat chewing in this community.
Predicting the probability of H3K4me3 occupation at a base pair from the genome sequence context
Authors: Ha Misook , Hong Soondo , Li Wen-Hsiung 
Published: March 2013

Abstract
Motivation: Histone modifications regulate chromatin structure and gene expression. Although nucleosome formation is known to be affected by primary DNA sequence composition, no sequence signature has been identified for histone modifications. It is known that dense H3K4me3 nucleosome sites are accompanied by a low density of other nucleosomes and are associated with gene activation. This observation suggests a different sequence composition of H3K4me3 from other nucleosomes.
Approach: To understand the relationship between genome sequence and chromatin structure, we studied DNA sequences at histone modification sites in various human cell types. We found sequence specificity for H3K4me3, but not for other histone modifications. Using the sequence specificities of H3 and H3K4me3 nucleosomes, we developed a model that computes the probability of H3K4me3 occupation at each base pair from the genome sequence context.
Results: A comparison of our predictions with experimental data suggests a high performance of our method, revealing a strong association between H3K4me3 and specific genomic DNA context. The high probability of H3K4me3 occupation occurs at transcription start and termination sites, exon boundaries and binding sites of transcription regulators involved in chromatin modification activities, including histone acetylases and enhancer- and insulator-associated factors. Thus, the human genome sequence contains signatures for chromatin modifications essential for gene regulation and development. Our method may be applied to find new sequence elements functioning by chromatin modulation.
Availability: Software and supplementary data are available at Bioinformatics online.
Contact: misook.ha@samsung.com or wli@uchicago.edu
Supplementary information: Supplementary data are available at Bioinformatics online.
Sorad: a systems biology approach to predict and modulate dynamic signaling pathway response from phosphoproteome time-course measurements
Authors: Äijö Tarmo , Granberg Kirsi , Lähdesmäki Harri 
Published: March 2013

Abstract
Motivation: Signaling networks mediate responses to different stimuli using a multitude of feed-forward, feedback and cross-talk mechanisms, and malfunctions in these mechanisms have an important role in various diseases. To understand a disease and to help discover novel therapeutic approaches, we have to reveal the molecular mechanisms underlying signal transduction and use that information to design targeted perturbations.
Results: We have pursued this direction by developing an efficient computational approach, Sorad, which can estimate the structure of signal transduction networks and the associated continuous signaling dynamics from phosphoprotein time-course measurements. Further, Sorad can identify experimental conditions that modulate the signaling toward a desired response. We have analyzed comprehensive phosphoprotein time-course data from a human hepatocellular liver carcinoma cell line and demonstrate here that Sorad provides more accurate predictions of phosphoprotein responses to given stimuli than previously presented methods and, importantly, that Sorad can estimate experimental conditions to achieve a desired signaling response. Because Sorad is data driven, it has a high potential to generate novel hypotheses for further research. Our analysis of the hepatocellular liver carcinoma data predict a regulatory connection where AKT activity is dependent on IKK in TGFα stimulated cells, which is supported by the original data but not included in the original model.
Availability: An implementation of the proposed computational methods will be available at http://research.ics.aalto.fi/csb/software/.
Contact: tarmo.aijo@aalto.fi or harri.lahdesmaki@aalto.fi
Supplementary information: Supplementary data are available at Bioinformatics online.
TfReg: calculating DNA and RNA melting temperatures and opening profiles with mesoscopic models
Authors: Weber Gerald 
Published: March 2013

Abstract
Summary: The mesoscopic statistical physics models, known generically as Peyrard–Bishop (PB) models, have found many applications for the study of oligonucleotide properties. Unfortunately, PB models have not reached a wider non-specialized audience for the lack of freely available software implementations. Here we present an extensible C++ implementation of four variants of the PB model, which allows the user to calculate melting temperatures from tested model parameters. Even for a non-specialist, it should be straightforward to change these parameters to reflect different experimental environments or different types of oligonucleotides. For users with some proficiency in C++ programming, it should be feasible to extend the code to other PB models owing to the generic programming implementation adopted for TfReg. Pre-calculated parameters are included that allow the immediate calculation of melting temperatures and thermal equivalence indexes for DNA and RNA.
Availability: C++ source code and compiled binaries for several Linux distributions are available from https://sites.google.com/site/geraldweberufmg/tfreg and from OpenSuse build service at http://build.opensuse.org.
Contact: gweberbh@gmail.com
Supplementary information: Supplementary data are available at Bioinformatics online.