bluuebunny/crossref_metadata_2025 huggingface dataset:
A METHOD FOR ESTIMATING PARALLAXES OF VCBS: MODIFICATION TO HIPPARCOS PARALLAX MEASUREMENTS
Authors: Al-WARDAT M. A. , TAANI A. , ASPLUND M.
Published: November 2013

We presented a method useful for estimating parallaxes of visually close binary stars (VCBS). The method depends on atmospheric modeling of the components of the VCBS. We construct model atmospheres by using a grid of Kurucz solar metalicity blanketed models1, which can be applied to calculate the synthetic spectral energy distribution for each component of the binary separately. In addition to study the entire system. However, the entire observational spectral energy distribution of the system was used as a reference for the comparison with the synthetic ones. We choose Hip4809 system to investigate the method, and we also study its physical and geometrical parameters. The new parallax of the system was estimated as π = 40.32 ± 5.00 mas, which disagrees with the Hipparcos parallax measurement (13.94 ± 0.90 mas). Furthermore the model atmosphere parameters of the components of the system were derived as: [Formula: see text], [Formula: see text], log ga = 4.50 ± 0.13, log gb = 4.50 ± 0.13, Ra = 0.94 ± 0.12R⊙, Rb = 0.93 ± 0.12R⊙, Depending on the derived parameters, the masses of the system's components were estimated as 1.03 ± 0.02M⊙ and 1.01 ± 0.02M⊙ for the primary and secondary components respectively, and their spectral types were concluded as G6V for both of them.
MAGNETIC FIELDS IN ACCRETION DISCS AROUND NEUTRON STARS — CONSEQUENCES FOR THE CHANGE OF SPIN
Authors: NASO LUCA , MILLER JOHN , KLUŹNIAK WLODEK
Published: November 2013

Accretion disks are ubiquitous in the universe and it is generally accepted that magnetic fields play a pivotal role in accretion-disk physics. The spin history of millisecond pulsars, which are usually classified as magnetized neutron stars spun up by an accretion disk, depends sensitively on the magnetic field structure, and yet highly idealized models from the 80s are still being used for calculating the magnetic field components. We present a possible way of improving the currently used models with a semi-analytic approach. The resulting magnetic field profile of both the poloidal and the toroidal component can be very different from the one suggested previously. This might dramatically change our picture of which parts of the disk tend to spin the star up or down.
MEASURING GRAVITOMAGNETIC EFFECTS BY MEANS OF RING LASERS
Authors: TARTAGLIA ANGELO
Published: November 2013

Light is a good probe for general relativistic effects. Exploiting the asymmetry of the propagation in the vicinity of a central rotating mass it is possible to use a ring laser in order to measure the frame dragging of the reference frames by the gravitational field of the Earth (Lense-Thirring effect). I shall present the G-GranSasso experiment whose objective is precisely to measure the Lense-Thirring and the de Sitter effects in a terrestrial laboratory. The experimental apparatus will be made of a set of at least three, differently oriented, ring lasers rigidly attached to a central "monument". The signal will be in the form of the beat frequency produced in the annular cavity of each laser by the rotational anisotropy. The laboratory will be located underground in the Laboratori Nazionali del Gran Sasso facility, in Italy. The required sensitivity is just one order of magnitude below the performance of the best existing instruments and the new design will attain it.
RECENT PROGRESS ON PULSAR OBSERVATIONS AT NANSHAN
Authors: WANG N. , YUAN J. P. , LIU Z. Y. , WANG J. B. , ZHU C.
Published: November 2013

Recent results of pulsar observations at Nanshan are present in this paper. In total 47 glitches were detected in the young pulsars, including a giant glitch in PSR B2334+61. We also investigated the scintillation parameters with the quasi-continuous observations of PSR B0329+54 spanning twenty days. Mainly using the same dataset, consecutive mode-switching events were analyzed in pulse profiles of PSR B0329+54.
MEASURING MAGNETIC FIELD OF NEUTRON STAR 4U 0115+63 WITH CYCLOTRON FEATURES
Authors: YAO SU , ZHANG CHENGMIN
Published: November 2013

We analyze the 3-80 keV spectrum of X-ray pulsar 4U 0115+63 taken by Rossi X-ray Timing Explorer(RXTE) on April 22nd, 2008. Two absorption features at ~13.5 keV and ~20.5 keV are detected by using cyclotron scattering feature profiles to fit the spectrum, ignoring the inadequate photons of the analyzed data. The fundamental feature is just right between ~11 and ~16 keV. It seems implausible to interprete these absorption lines as cyclotron features because of their inharmonic behavior, even when relativistic effect has been taken into account. But it is possible that the main region where first harmonic line forms is slightly different from the fundamental one.
RADIUS CONSTRAINT OF THE RECYCLED DOUBLE PULSAR PSR J0737-3039
Authors: ZHAO HAIHUI , SONG LIMING , ZHANG CHENGMIN
Published: November 2013

We investigate the radius of the recycled pulsar in double pulsar system PSR J0737-3039. In the standard accretion spin-up model, the recycled pulsar spin up continues until arriving at a minimum spin period, or so-called "equilibrium period", which is related to the stellar magnetic field, the accretion rate and radius. The generic spin-down age may give realistic estimates for normal pulsar PSR J0737-3039B, since its present spin period is much longer than the one at birth. In this paper, we estimate the radius of millisecond pulsar (MSP) PSR J0737-3039A by assuming its true age is same as the spin-down age of its companion PSR J0737-3039B. We find that the radius of recycled pulsar PSR J0737-3039A ranges approximately from 12 to 38 km, and it should be far from the composition of strange quark matters, as shown in the mass-radius diagram.
LONG GRB WITH ADDITIONAL HIGH ENERGY MAXIMA AFTER THE END OF THE LOW ENERGY T90 INTERVALS
Authors: IRENE ARKHANGELSKAJA , ALEXANDER ZENIN , DMITRY KIRIN , ELENA VOEVODINA
Published: November 2013

Now GRB high energy γ-emission was observed mostly by detectors onboard Fermi and Agile satellites. During most part of GRB high energy γ-emission registered some later than low energy trigger and lasts several hundreds of seconds, but its maxima are within low energy t90 intervals both for short and long bursts. But GRB090323, GRB090328 and GRB090626 temporal profiles have additional maxima after low energy t90 intervals finished. These bursts temporal profile analysis have shown that faint peaks in low energy bands close to the ends of low energy t90 intervals preceded such maxima. Moreover, these events low energy spectral index β behavior differs from usual GRB one according to preliminary analysis. We suppose that these GRB could be separated as different GRB type. In presented article this new GRB type properties are discussed.
NEUTRON STAR CORES IN THE GENERAL RELATIVISTIC THOMAS-FERMI TREATMENT
Authors: BELVEDERE RICCARDO , RUEDA JORGE A. , RUFFINI REMO
Published: November 2013

We introduce a new set of equations to describe the equilibrium of the core of neutron stars, composed by self-gravitating degenerate neutrons, protons and electrons in β-equilibrium. We take into account strong, weak, electromagnetic and gravitational interactions within the framework of general relativity. We extend the conditions of equilibrium based on the constancy of the Klein potentials to the strongly interactive case. The strong interactions between nucleons are modeled through the exchange of the σ, ω and ρ virtual mesons. The equations are solved numerically in the case of zero temperatures and for a non-rotating spherically symmetric neutron stars in the mean-field approximation.
Be X-RAY TRANSIENT 4U 0115+63 IN 2008 OUTBURST
Authors: LI JUN , WANG WEI , ZHAO YONGHENG
Published: November 2013

We present both timing and spectral analysis of the outburst of 4U 0115+63 in 2008 with INTEGRAL and RXTE observations. We have determined the spin period of the neutron star at ~ 3.61422 ± 0.00011 s, and a spin up rate during the outburst of Ṗ = (-2.66 ± 1.81) × 10-6s d-1, the angle of periapsis ω = 49.6° ± 0.68° in 2008 and its variation (apsidal motion) [Formula: see text] when comparing with previous measured values. During the outburst, four cyclotron absorption lines were detected (fundamental line at 10–15 keV; 2nd harmonic at 22 keV; 3rd at ~ 34 keV, 4th at ~ 42 keV), the fifth harmonic around 54 keV was also hinted in our data. The fundamental absorption line energy varies during the outburst: around 15 keV during the rising phase, and transiting to ~ 10 keV during the peak of the outburst, and further coming back to ~ 15 keV during the decreasing phase. The photon index shows the correlation with the fundamental line energy: the source becomes harder around the peak of the outburst and softer in both rising and decreasing phases. This correlation and transition processes during the outburst need further studies in both observations and theoretical work.
QUARK-CLUSTER STARS: THE STRUCTURE
Authors: LAI XIAOYU , XU RENXIN
Published: November 2013

The nature of pulsar-like compact stars is still in controversy although the first pulsar was found more than 40 years ago. Generally speaking, conventional neutron stars and non-mainstream quark stars are two types of models to describe the inner structure of pulsars, with the former composed mainly of hadrons and the latter of a peculiar kind of matter whose state equation should be understood in the level of quarks rather than hadrons. To construct a more realistic model from both theoretical and observational points of view, we conjecture that pulsars could be "quark-cluster stars" which are composed of quark-clusters with almost equal numbers of up, down and strange quarks. Clustering quark matter could be the result of strong coupling between quarks inside realistic compact stars. The lightest quark clusters could be of H-dibaryons, while quark clusters could also be heavier with more quarks. Being essentially related to the non-perturbative quantum-chromo dynamics (QCD), the state of supra-nuclear condensed matter is really difficult to obtain strictly by only theoretical QCD-calculations, and we expect, nevertheless, that astrophysical observations could help us to have a final solution.
EFFECTS OF MAGNETIC FIELD ON THE STRUCTURE OF NEUTRINO-DOMINATED ACCRETION DISK
Authors: LIN YIQING
Published: November 2013

By taking magnetic field and detailed microphysics into account, we calculate the structure of neutrino-dominated disk in the frame of the well-known Paczyski-Witta potential, and compare the results with those without magnetic field. The results show that the temperature of the disk is lower than that without magnetic field, whereas the density is nearly the same as that without magnetic field. There also exists difference in the composition of disk matter between these two cases in the inner region of the disk.
CORRELATION BETWEEN HARDNESS RATIO AND DURATION OF FERMI GAMMA-RAY BURSTS
Authors: ZHANG FU-WEN
Published: November 2013

Using the latest gamma-ray bursts (GRB) observed by Fermi-GBM, we perform a statistical analysis of the relation between hardness ratio (HR) and duration (ΔT) of GRBs, and find that HR and ΔT are still anti-correlated. we also find that this correlation strongly depends upon the spectral shape of GRBs and energy bands, and the bursts with the curved spectra in the typical BATSE energy bands show a tighter anti-correlation than those with the power-law spectra in the typical BAT energy bands. This might explain why the HR – ΔT correlation is not evident for Swift-BAT GRB sample as well as other GRB sample detected by instruments with a narrower/softer energy bandpass such as HETE-2.
TECHNICAL ASPECTS IN DARK MATTER DIRECT DETECTION
Authors: BERNABEI R. , BELLI P. , DI MARCO A. , MONTECCHIA F. , CAPPELLA F. , d'ANGELO A. , INCICCHITTI A. , PROSPERI D. , CARACCIOLO V. , CERULLI R. , DAI C. J. , HE H. L. , MA X. H. , SHENG X. D. , WANG R. G. , YE Z. P.
Published: November 2013

In the field of dark matter direct detection, on the one hand, it is predicted by theoretical models that many dark matter candidates and scenarios are possible. On the other hand, a variety of detectors has been proposed, but most of them — by the fact — are still at R&D stage. Such a situation leads to some considerations on technical aspects on dark matter direct detection.
SELF-GRAVITATING SYSTEM OF SEMIDEGENERATED FERMIONS AS CENTRAL OBJECTS AND DARK MATTER HALOS IN GALAXIES
Authors: FRAGA BERNARDO M. O. , ARGÜELLES CARLOS R. , RUFFINI REMO
Published: November 2013

We propose a unified model for dark matter haloes and central galactic objects as a self-gravitating system of semidegenerated fermions in thermal equilibrium. We consider spherical symmetry and then we solve the equations of gravitational equilibrium using the Fermi integrals in a dimensionless manner, obtaining the density profile and velocity curve. We also obtain scaling laws for the observables of the system and show that, for a wide range of our parameters, our model is consistent with the so called universality of the surface density of dark matter.
SPIN FOAM AND REGGE CALCULUS
Authors: GIONTI S. J. GABRIELE
Published: November 2013

Recent results in Local Regge Calculus are confronted with Spin Foam Formalism. Introducing Barrett-Crane Quantization in Local Regge Calculus makes it possible to associate a unique Spin jh with an hinge h, fulfilling one of the requirements of Spin Foam definition. It is shown that inter-twiner terms of Spin Foam can follow from the closure constraint in Local Regge Calculus.
STATISTICAL ORIGIN OF SPECIAL AND DOUBLY SPECIAL RELATIVITY
Authors: JIZBA PETR , SCARDIGLI FABIO
Published: November 2013

We show how a Brownian motion on a short scale can originate a relativistic motion on scales larger than particle's Compton wavelength. Special relativity appears to be not a primitive concept, but rather it statistically emerges when a coarse graining average over distances of order, or longer than the Compton wavelength is taken. Our scheme accommodates easily also the doubly special relativistic dynamics. A previously unsuspected, common statistical origin of the two frameworks is brought to light for the first time.
COSMOLOGICAL SHOCK WAVES IN THE LARGE SCALE STRUCTURE OF THE UNIVERSE
Authors: MA RENYI , RYU DONGSU , KANG HYESUNG
Published: November 2013

Based on the cosmological hydrodynamic simulation, we study the properties of shock waves formed during the formation of the large scale structure (LSS) of the universe, and investigate their contribution to the cosmic ray (CR) fraction in the intergalactic medium (IGM). It is found that while strong accretion shocks prevail at high redshift, weak internal shocks become dominant in the intracluster medium (ICM) as galaxy clusters form and virialize at low redshift, z < 1. The accumulated CR proton energy is likely to be less than 10 % of the thermal energy in the ICM, since weak shocks of M ≲ 3 are most abundant. This is consistent with the upper limit constrained by radio and gamma-ray observations of galaxy clusters. In the warm-hot medium (WHIM) inside filaments, CRs and gas could be almost in energy equipartition, since relatively stronger shocks of 5 ≲ M ≲ 10 are dominant there. We suggest that the non-thermal emissions from the CR electrons and protons accelerated by cosmological shock waves could provide a new way to detect the WHIM of the universe.
MEASURING SOLAR DIAMETER WITH 2012 VENUS TRANSITS
Authors: SIGISMONDI COSTANTINO
Published: November 2013

The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the solar diameter is recovered. The black drop and seeing effects are overcome with two fitting circles, to Venus and to the Sun, drawn in the undistorted part of the image. The corrections of ephemerides due to the atmospheric refraction will also be taken into account. The forthcoming transit of Venus will allow an accuracy on the diameter of the Sun better than 0.01 arcsec, with good images of the ingress and of the egress taken each second. Chinese solar observatories are in the optimal conditions to obtain valuable data for the measurement of the solar diameter with the Venus transit of 5/6 June 2012 with an unprecedented accuracy, and with absolute calibration given by the ephemerides.
Sourcing stone for the conservation and repair of historical buildings in Britain
Authors: Lott Graham
Published: November 2013

Stone for the construction of buildings and monuments has been locally quarried from most parts of Britain’s lithologically diverse geological succession starting about 3500 years ago. Each part of the geological column, from the Precambrian to Quaternary, has yielded stone for building, providing a colourful palette for Britain’s stone architecture and monuments. For those involved in conserving these structures this diversity of stone types has become an increasing problem as many of the original quarries have long since stopped working and the stones have disappeared from the marketplace. This lack of an adequate range of indigenous stones suitable for conservation repair and for sympathetic new-build projects is a continuing concern for heritage organizations, property owners and developers in Britain. There are a number of ways in which this problem is being addressed. It is clearly important to demonstrate the scale of the problem by collating sufficient information to identify those stones (and, therefore, those stone structures) most under threat. Although some vernacular stones were often used widely others appear in only a small number of buildings. A national database of all indigenous stone sources and an assessment of their extent of use is, therefore, essential. Subsequent analysis of the data gathered will then allow those stones that are of critical concern to be identified, which might generate sufficient interest and economic potential for quarry operators to consider reopening sites for new stone production. This contribution is an attempt to give an overview of the former extent of the building stone resources of Britain to illustrate the magnitude of the current problems of stone supply.
Evolution of the Modern Broiler and Feed Efficiency
Authors: Siegel Paul B.
Published: November 2013

Although the chicken was domesticated during the Neolithic period, the development of the modern broiler is a recent event that has occurred within the past 100 years. The chicken’s adaptability has allowed it to be grown globally under a range of husbandry conditions. That is, the same genetic stock may be found in a range of environments, where it is noted for rapid growth to market weight and efficiency of feed use, which has increased dramatically, mainly through genetic selection. Under good husbandry and a high-energy diet, at 35 days of age a 1.40-kg broiler required 3.22 kg of feed in 1985. Twenty-five years later, we have a 2.44-kg broiler produced on 3.66 kg of feed. This review attempts to address the history of factors contributing to these changes, obstacles that have had to be overcome, and future limitations.
Human adaptation to the hypoxia of high altitude: the Tibetan paradigm from the pregenomic to the postgenomic era
Authors: Petousi Nayia , Robbins Peter A.
Published: November 2013

The Tibetan Plateau is one of the highest regions on Earth. Tibetan highlanders are adapted to life and reproduction in a hypoxic environment and possess a suite of distinctive physiological traits. Recent studies have identified genomic loci that have undergone natural selection in Tibetans. Two of these loci, EGLN1 and EPAS1, encode major components of the hypoxia-inducible factor transcriptional system, which has a central role in oxygen sensing and coordinating an organism's response to hypoxia, as evidenced by studies in humans and mice. An association between genetic variants within these genes and hemoglobin concentration in Tibetans at high altitude was demonstrated in some of the studies ( 8 , 80 , 96 ). Nevertheless, the functional variants within these genes and the underlying mechanisms of action are still not known. Furthermore, there are a number of other possible phenotypic traits, besides hemoglobin concentration, upon which natural selection may have acted. Integration of studies at the genomic level with functional molecular studies and studies in systems physiology has the potential to provide further understanding of human evolution in response to high-altitude hypoxia. The Tibetan paradigm provides further insight on the role of the hypoxia-inducible factor system in humans in relation to oxygen homeostasis.
Physiology in Medicine: Obstructive sleep apnea pathogenesis and treatment—considerations beyond airway anatomy
Authors: Dempsey Jerome A. , Xie Ailiang , Patz David S. , Wang David
Published: November 2013

We review evidence in support of significant contributions to the pathogenesis of obstructive sleep apnea (OSA) from pathophysiological factors beyond the well-accepted importance of airway anatomy. Emphasis is placed on contributions from neurochemical control of central respiratory motor output through its effects on output stability, upper airway dilator muscle activation, and arousability. In turn, we consider the evidence demonstrating effective treatment of OSA via approaches that address each of these pathophysiologic risk factors. Finally, a case is made for combining treatments aimed at both anatomical and ventilatory control system deficiencies and for individualizing treatment to address a patient 's own specific risk factors.
Safety of 20-Gauge Transconjunctival Sutureless Vitrectomy
Authors: Papaefthymiou Ioannis , Petropoulos Ioannis K. , Mangioris George , Mendrinos Efstratios , Pournaras Constantin J.
Published: November 2013

Purpose: To study the safety of 20-gauge transconjunctival sutureless vitrectomy. Methods: Clinical data of patients who underwent 20-gauge transconjunctival sutureless vitrectomy for the first time, for various disorders, were reviewed retrospectively. The main outcome measures were the number of sclerotomies requiring suturing as well as the intra- and postoperative complications. Results: A total of 179 operations were performed. Indications for vitrectomy included 68 idiopathic epiretinal membranes, 26 macular holes, 23 phakic and 16 pseudophakic retinal detachments, and 46 various other, less common etiologies. Of these 179 operations, 166 (93%) were sutureless. Of the 537 sclerotomies created, 25 (5%) received a single transconjunctival-scleral suture. Intraoperative complications included premature dislodging of the cannulas in 2 sclerotomies and an iatrogenic horseshoe tear at 1 sclerotomy site. Postoperative complications comprised transient hypotony in 14 cases, subconjunctival gas in 2 cases, and choroidal effusion in 1 case. No serious complications (such as endophthalmitis) were observed. Conclusion: 20-gauge transconjunctival sutureless vitrectomy can be considered safe, as the intra- and postoperative complications observed are neither numerous nor significant. Sclerotomies appear to be safe and relatively easy to perform, without compromising the advantages of sutureless surgery.
Direct Targeting of the Thalamic Anteroventral Nucleus for Deep Brain Stimulation by T1-Weighted Magnetic Resonance Imaging at 3 T
Authors: Buentjen Lars , Kopitzki Klaus , Schmitt Friedhelm C. , Voges Juergen , Tempelmann Claus , Kaufmann Joern , Kanowski Martin
Published: November 2013

Background: The thalamic anteroventral nucleus (AV) is a promising target structure for deep brain stimulation (DBS) in patients suffering from refractory epilepsy. Direct visualization of the AV would improve spatial accuracy in functional stereotactic neurosurgery for treatment of this disease. Methods: On 3-tesla magnetic resonance imaging (MRI), acquisition parameters were adjusted for optimal demarcation of the AV in 1 healthy subject. Reliability of AV visualization was then evaluated in 5 healthy individuals and 3 patients with refractory epilepsy. Results: In all individuals, an adjusted T1-weighted sequence allowed for demarcation of the AV. It was clearly distinguishable from hyperintense myelin-rich lamellae surrounding it ventrally and laterally and appeared hypo-intense compared to the adjacent thalamic nuclei. Image resolution and contrast facilitated direct stereotactic targeting of the AV prior to DBS surgery in all 3 patients. Conclusions: Direct targeting of the AV can be achieved, which has immediate implications for the accuracy of MRI-guided DBS in patients with refractory epilepsy.
Single-Institution Retrospective Series of Gamma Knife Radiosurgery in the Treatment of Multiple Sclerosis-Related Trigeminal Neuralgia: Factors that Predict Efficacy
Authors: Weller Michael , Marshall Kopriva , Lovato James F. , Bourland J. Daniel , deGuzman Allan F. , Munley Michael T. , Shaw Edward G. , Tatter Stephen B. , Chan Michael D.
Published: November 2013

Background: Gamma knife radiosurgery (GKRS) has been reported as a treatment option for multiple sclerosis (MS)-related trigeminal neuralgia. Objective: To report the outcomes of a single-institution retrospective series of MS-related trigeminal neuralgia. Methods: Between 2002 and 2010, 35 patients with MS-related trigeminal neuralgia were treated with GKRS. The median maximum dose was 90 Gy. Data were analyzed to determine the response to GKRS and factors that may predict for efficacy. Results: Of the 35 patients, 88% experienced a Barrow Neurological Institute (BNI) pain score of I-III at 3 months after GKRS. Kaplan-Meier estimates of 1-, 2- and 5-year freedom from BNI IV-V pain relapse were 57, 57 and 52%, respectively. Numbness was experienced by 39% of patients after GKRS, though no patients reported bothersome numbness. Several differences were noted between how the MS-related variant responded to GKRS and what has previously been reported for idiopathic trigeminal neuralgia. These include the observations that development of post-GKRS numbness did not predict for treatment response (p = 0.62) and that dorsal root entry zone dose did not predict for freedom from pain relapse (odds ratio 1.01, p = 0.1). Active smoking predicted for freedom from pain relapse (odds ratio 67.4, p = 0.04). Conclusion: GKRS is a viable noninvasive treatment option for MS-related trigeminal neuralgia.
Patient-Reported Difference following Implantation of a Blue Light-Filtering Aspheric Intraocular Lens and a UV-Filtering Aspheric Intraocular Lens
Authors: Schweitzer Cédric , Colin Joseph
Published: November 2013

We report on a series of 6 patients who experienced yellow vision after uncomplicated cataract surgery in their second eye. In the first eye, an aspheric blue-light filtering intraocular lens (IOL) was implanted, followed by the implantation of a 1-Piece aspheric IOL in the second eye. The time between the surgeries ranged from 12 months to 3 years. The patients experienced noticeable differences between the yellow and the clear lens. It is suggested to avoid mixing blue light-filtering and UV-filtering IOLs in the same patient, particularly in those who have high expectations following cataract surgery.
Plasma S100A8/A9 Correlates With Blood Neutrophil Counts, Traditional Risk Factors, and Cardiovascular Disease in Middle-Aged Healthy Individuals
Authors: Cotoi Ovidiu S. , Dunér Pontus , Ko Nayoung , Hedblad Bo , Nilsson Jan , Björkbacka Harry , Schiopu Alexandru
Published: November 2013

Objective—

The S100 alarmins A8, A9, and A8/A9, secreted by activated neutrophils and monocytes/macrophages, are involved in the pathogenesis of various inflammatory diseases. S100A8/A9 has previously been linked to atherogenesis and cardiovascular (CV) disease. We investigated whether S100A8, A9, and A8/A9 correlate with carotid artery disease and CV risk in apparently healthy individuals.

Approach and Results—

We measured baseline S100A8, A9, and A8/A9 in 664 individuals aged 63 to 68 years, with no previous history of CV disease, randomly selected from the Malmö Diet and Cancer population cohort. We examined the correlations between S100 proteins and circulating cell populations, plasma cytokines, carotid artery disease, and incidence of CV events during a median follow-up period of 16.2 years. We found that plasma S100A8/A9 concentration is positively influenced by circulating neutrophil numbers, smoking, body mass index, glycosylated hemoglobin A1c, and low-density lipoprotein. High-density lipoprotein was negatively associated with S100A8/A9. S100A8/A9 and the neutrophil counts were positively correlated with intima-media area in the common carotid artery, independently of age, sex, and CV risk factors. S100A8/A9 and circulating neutrophils presented similar associations with the incidence of coronary events (hazard ratio [95% confidence interval] per 1 SD: 1.28 [1.03–1.59] and 1.26 [1.04–1.53], respectively) and CV death (1.34 [1.06–1.71] and 1.59 [1.33–1.90], respectively). These relationships were mainly supported by strong associations in women, which were independent of traditional risk factors. There were no independent relationships between S100A8 and S100A9, and CV disease.

Conclusions—

Our study supports the value of S100A8/A9 as a potentially important link between neutrophils, traditional CV risk factors, and CV disease.
Importance of Evaluating Cell Cholesterol Influx With Efflux in Determining the Impact of Human Serum on Cholesterol Metabolism and Atherosclerosis
Authors: Weibel Ginny L. , Drazul-Schrader Denise , Shivers Debra K. , Wade Alisha N. , Rothblat George H. , Reilly Muredach P. , de la Llera-Moya Margarita
Published: November 2013

Objective—

Cholesterol efflux relates to cardiovascular disease but cannot predict cellular cholesterol mass changes. We asked whether influx and net flux assays provide additional insights.

Approach and Results—

Adapt a bidirectional flux assay to cells where efflux has clinical correlates and examine the association of influx, efflux, and net flux to serum triglycerides (TGs). Apolipoprotein B–depleted (high-density lipoprotein-fraction) serum from individuals with unfavorable lipids (median [interquartile range]; high-density lipoprotein-cholesterol=39 [32–42], low-density lipoprotein-cholesterol=109 [97–137], TGs=258 [184–335] mg/dL; n=13) promoted greater ATP-binding cassette transporter A1–mediated [1,2-
3H
] cholesterol efflux (3.8±0.3%/4 hour versus 1.2±0.4%/4 hour;
P
<0.0001) from cyclic 3’,5’-amp(CTP-amp)-treated J774 macrophages than from individuals with favorable lipids (high-density lipoprotein-cholesterol=72 [58–88], low-density lipoprotein-cholesterol=111 [97–131], TGs=65 [56–69] mg/dL; n=10). Thus, high TGs associated with more ATP-binding cassette transporter A1 acceptors. Efflux of cholesterol mass (μg free cholesterol/mg cell protein per 8 hour) to serum was also higher (7.06±0.33 versus 5.83±0.48;
P
=0.04). However, whole sera from individuals with unfavorable lipids promoted more influx (5.14±0.65 versus 2.48±0.85;
P
=0.02) and lower net release of cholesterol mass (1.93±0.46 versus 3.36±0.47;
P
=0.04). The pattern differed when mass flux was measured using apolipoprotein B–depleted serum rather than serum. Although individuals with favorable lipids tended to have greater influx than those with unfavorable lipids, efflux to apolipoprotein B–depleted serum was markedly higher (6.81±0.04 versus 2.62±0.14;
P
<0.0001), resulting in an efflux:influx ratio of ≈3-fold. Thus both serum and apolipoprotein B–depleted serum from individuals with favorable lipids promoted greater net cholesterol mass release despite increased ATP-binding cassette transporter A1–mediated efflux in samples of individuals with high TGs/unfavorable lipids.

Conclusions—

When considering the efficiency of serum specimens to modulate cell cholesterol content, both influx and efflux need to be measured.
Clinical-Grade Human Neural Stem Cells Promote Reparative Neovascularization in Mouse Models of Hindlimb Ischemia
Authors: Katare Rajesh , Stroemer Paul , Hicks Caroline , Stevanato Lara , Patel Sara , Corteling Randolph , Miljan Erik , Vishnubhatla Indira , Sinden John , Madeddu Paolo
Published: November 2013

Objective—

CTX0E03 (CTX) is a clinical-grade human neural stem cell (hNSC) line that promotes angiogenesis and neurogenesis in a preclinical model of stroke and is now under clinical development for stroke disability. We evaluated the therapeutic activity of intramuscular CTX hNSC implantation in murine models of hindlimb ischemia for potential translation to clinical studies in critical limb ischemia.

Approach and Results—

Immunodeficient (CD-1 Fox
nu/nu
) mice acutely treated with hNSCs had overall significantly increased rates and magnitude of recovery of surface blood flow (laser Doppler), limb muscle perfusion (fluorescent microspheres,
P
<0.001), and capillary and small arteriole densities in the ischemic limb (fluorescence immunohistochemistry, both
P
<0.001) when compared with the vehicle-treated group. Hemodynamic and anatomic improvements were dose related and optimal at a minimum dose of 3×10
5
cells. Dose-dependent improvements in blood flow and increased vessel densities by hNSC administration early after ischemia were confirmed in immunocompetent CD-1 and streptozotocin-induced diabetic mice, together with marked reductions in the incidence of necrotic toes (
P
<0.05). Delayed administration of hNSCs, 7 days after occlusion, produced restorative effects when comparable with acute treatment of 35 days after hindlimb ischemia. Histological studies in hindlimb ischemia immunocompetent mice for the first 7 days after treatment revealed short-term hNSC survival, transient elevation of early host muscle inflammatory, and angiogenic responses and acceleration of myogenesis.

Conclusions—

hNSC therapy represents a promising treatment option for critical limb ischemia.
Genome-Wide Interaction Study Identifies
RCBTB1
as a Modifier for Smoking Effect on Carotid Intima-Media Thickness
Authors: Wang Liyong , Rundek Tatjana , Beecham Ashley , Hudson Barry , Blanton Susan H. , Zhao Hongyu , Sacco Ralph L. , Dong Chuanhui
Published: November 2013

Objective—

Carotid intima-media thickness (cIMT), a marker for atherosclerosis, is affected by smoking and has substantial interindividual variation. We sought to identify the genetic moderators influencing the effect of smoking on cIMT.

Approach and Results—

With a multistage design using 722 379 single nucleotide polymorphisms (SNP), a genome-wide interaction study was performed in a discovery sample of 669 Hispanics, followed by replication in 589 subjects (264 Hispanics, 172 non-Hispanic blacks, 153 non-Hispanic whites). Assuming an additive genetic model, regression analysis was performed to test for smoking–SNP interaction on cIMT while controlling for age, sex, and the top 3 principal components of ancestry. The strongest interaction in Hispanics was found with a synonymous splicing SNP (rs3751383) in exon 9 of
RCBTB1
(
P
=2.5e
−6
in discovery sample;
P
=0.01 in the Hispanic replication sample;
P
<8.8e
−9
in the combined Hispanic sample). Stratification analysis in the combined Hispanic sample showed that smoking had no effect on cIMT among rs3751383 G homozygote (
P
=0.15), a moderate effect among rs3751383 heterozygote (
P
=0.01), and a strong effect among rs3751383 A homozygote (
P
=2.1e
−7
). A consistent trend was observed in the non-Hispanic white and black data sets, leading to an interaction effect of
P
<2.9e
−9
in the meta-analysis of all 1258 subjects.

Conclusions—

Our study represents the first genome-wide smoking–SNP interaction study of cIMT and identifies
RCBTB1
as a modifier of the smoking effect on cIMT. Testing for gene–environment interactions can help uncover genetic factors that contribute to the interindividual variation in response to the same environmental exposure.
Genetic Influences on Trajectories of Systolic Blood Pressure Across Childhood and Adolescence
Authors: Howe Laura D. , Parmar Priyakumari G. , Paternoster Lavinia , Warrington Nicole M. , Kemp John P. , Briollais Laurent , Newnham John P. , Timpson Nicholas J. , Smith George Davey , Ring Susan M. , Evans David M. , Tilling Kate , Pennell Craig E. , Beilin Lawrie J. , Palmer Lyle J. , Lawlor Debbie A.
Published: November 2013

Background—

Blood pressure (BP) tends to increase across childhood and adolescence, but the genetic influences on rates of BP change are not known. Potentially important genetic influences could include genetic variants identified in genome-wide association studies of adults as being associated with BP, height, and body mass index. Understanding the contribution of these genetic variants to changes in BP across childhood and adolescence could yield understanding into the life course development of cardiovascular risk.

Methods and Results—

Pooling data from 2 cohorts (the Avon Longitudinal Study of Parents and Children [n=7013] and the Western Australian Pregnancy Cohort [n=1459]), we examined the associations of allelic scores of 29 single-nucleotide polymorphisms (SNPs) for adult BP, 180 height SNPs, and 32 body mass index SNPs, with trajectories of systolic BP (SBP) from 6 to 17 years of age, using linear spline multilevel models. The allelic scores of BP and body mass index SNPs were associated with SBP at 6 years of age (per-allele effect sizes, 0.097 mm Hg [SE, 0.039 mm Hg] and 0.107 mm Hg [SE, 0.037 mm Hg]); associations with age-related changes in SBP between 6 and 17 years of age were of small magnitude and imprecisely estimated. The allelic score of height SNPs was only weakly associated with SBP changes. No sex or cohort differences in genetic effects were observed.

Conclusions—

Allelic scores of BP and body mass index SNPs demonstrated associations with SBP at 6 years of age with a similar magnitude but were not strongly associated with changes in SBP with age between 6 and 17 years. Further work is required to identify variants associated with changes with age in BP.
Long-Term Coffee Consumption and Risk of Cardiovascular Disease
Authors: Ding Ming , Bhupathiraju Shilpa N. , Satija Ambika , van Dam Rob M. , Hu Frank B.
Published: November 2013

Background—

Considerable controversy exists on the association between coffee consumption and cardiovascular disease (CVD) risk. A meta-analysis was performed to assess the dose–response relationship of long-term coffee consumption with CVD risk.

Methods and Results—

PubMed and EMBASE were searched for prospective cohort studies of the relationship between coffee consumption and CVD risk, which included coronary heart disease, stroke, heart failure, and CVD mortality. Thirty-six studies were included with 1 279 804 participants and 36 352 CVD cases. A nonlinear relationship of coffee consumption with CVD risk was identified (
P
for heterogeneity=0.09,
P
for trend <0.001,
P
for nonlinearity <0.001). Compared with the lowest category of coffee consumption (median, 0 cups per day), the relative risk of CVD was 0.95 (95% confidence interval, 0.87–1.03) for the highest category (median, 5 cups per day) category, 0.85 (95% confidence interval, 0.80–0.90) for the second highest category (median, 3.5 cups per day), and 0.89 (95% confidence interval, 0.84–0.94) for the third highest category (median, 1.5 cups per day). Looking at separate outcomes, coffee consumption was nonlinearly associated with both coronary heart disease (
P
for heterogeneity=0.001,
P
for trend <0.001,
P
for nonlinearity <0.001) and stroke (
P
for heterogeneity=0.07,
P
for trend <0.001,
P
for nonlinearity <0.001;
P
for trend differences >0.05) risks.

Conclusions—

A nonlinear association between coffee consumption and CVD risk was observed in this meta-analysis. Moderate coffee consumption was inversely significantly associated with CVD risk, with the lowest CVD risk at 3 to 5 cups per day, and heavy coffee consumption was not associated with elevated CVD risk.
Predicting Asymptomatic Coronary Artery Diseasein Patients With Ischemic Stroke and Transient Ischemic Attack
Authors: Calvet David , Song Dongbeom , Yoo Joonsang , Turc Guillaume , Sablayrolles Jean-Louis , Choi Byoung Wook , Heo Ji Hoe , Mas Jean-Louis
Published: November 2013

Background and Purpose—

Identifying occult coronary artery stenosis may improve secondary prevention of stroke patients. The aim of this study was to derive and validate a simple score to predict severe occult coronary artery stenosis in stroke patients.

Methods—

We derived a score from a French hospital–based cohort of consecutive patients (n=300) who had an ischemic stroke or a transient ischemic attack and no previous history of coronary heart disease (Predicting Asymptomatic Coronary Artery Disease in Patients With Ischemic Stroke and Transient Ischemic Attack [PRECORIS] score) and validated the score in a similar Korean cohort (n=1602). In both cohorts, severe coronary artery stenosis was defined by the presence of at least 1 ≥50% coronary artery stenosis as detected by 64-section CT coronary angiography.

Results—

A 5-point score (Framingham Risk Score–predicted 10-year coronary heart disease risk [≥20%=3; 10–19%=1; <10%=0] and cervicocephalic artery stenosis [≥50%=2; <50%=1; none=0]) was predictive of occult ≥50% coronary artery stenosis risk in the derivation cohort (C-statistic=0.77 [0.70–0.84]) and in the validation cohort (C-statistic=0.66 [0.63–0.68]). The predictive ability of the score was even stronger when only ≥50% left main trunk disease or 3-vessel disease were considered (C-statistic=0.83 [0.74–0.92] and 0.70 [0.66–0.74] in derivation and validation cohorts, respectively). The prevalence of occult ≥50% coronary artery stenosis and ≥50% left main trunk or 3-vessel disease increased gradually with the PRECORIS score, reaching 44.2% and 13.5% in derivation cohort and 49.8% and 12.8% in validation cohort in patients with a PRECORIS score ≥4.

Conclusions—

The PRECORIS score can identify a population of stroke or transient ischemic attack patients with a high prevalence of occult severe coronary artery stenosis.
MicroRNA-18a Improves Human Cerebral Arteriovenous Malformation Endothelial Cell Function
Authors: Ferreira Raquel , Santos Tiago , Amar Arun , Tahara Stanley M. , Chen Thomas C. , Giannotta Steven L. , Hofman Florence M.
Published: November 2013

Background and Purpose—

Cerebral arteriovenous malformation (AVM) is a vascular disease that disrupts normal blood flow and leads to serious neurological impairment or death. Aberrant functions of AVM-derived brain endothelial cells (AVM-BECs) are a disease hallmark. Our aim was to use microRNA-18a (miR-18a) as a therapeutic agent to improve AVM-BEC function.

Methods—

Human AVM-BECs were tested for growth factor production and proliferation under different shear flow conditions and evaluated for tubule formation. Thrombospondin-1, inhibitor of DNA-binding protein 1, and vascular endothelial growth factor (VEGF) isotype mRNA levels were quantified by quantitative real-time polymerase chain reaction. Thrombospondin-1, VEGF-A, and VEGF-D protein expression was measured using enzyme-linked immunosorbent assay. Proliferation and tubule formation were evaluated using bromodeoxyuridine incorporation and growth factor–reduced Matrigel assays, respectively.

Results—

miR-18a increased thrombospondin-1 production but decreased inhibitor of DNA-binding protein 1, a transcriptional repressor of thrombospondin-1. miR-18a reduced VEGF-A and VEGF-D levels, both overexpressed in untreated AVM-BECs. This is the first study reporting VEGF-D overexpression in AVM. These effects were most prominent under arterial shear flow conditions. miR-18a also reduced AVM-BEC proliferation, improved tubule formation, and was effectively internalized by AVM-BECs in the absence of extraneous transfection reagents.

Conclusions—

We report VEGF-D overexpression in AVM and the capacity of miR-18a to induce AVM-BECs to function more normally. This highlights the clinical potential of microRNA as a treatment for AVM and other vascular diseases.
Morphological and anatomical characterization of a new natural hybrid between Cohniella ascendens and C. brachyphylla (Oncidiinae: Orchidaceae)
Authors: CETZAL-IX WILLIAM , CARNEVALI GERMAN , NOGUERA-SAVELLI ELIANA , JAUREGUI DAMELIS
Published: November 2013

A putative natural hybrid between Cohniella ascendens and C. brachyphylla (Orchidaceae, Oncidiinae) from western Costa Rica, C. ×francoi, is herein newly described, illustrated and characterized based upon both morphological and anatomical characters. This taxon hybrid is most similar to C. ascendens but the flowers show intermediate characters between the putative parents. Cohniella ×francoi is similar to C. ascendens in its semipendulous inflorescences, callus shape, cylindrical column base with linear oblong wings, and obovate stigmatic cavity plus several anatomical characters. On the other hand, it is similar to C. brachyphylla in the oblong to subquadrate lateral lobes of the labellum that are in the same plane as the central lobe, and the rectangular disc of the labellum with a lateral extension of the callus in the margins. A table of diagnostic characters for the new hybrid and its putative parents, a comparative figure, and a map showing their geographical distributions are also provided.  Cohniella ×francoi, un híbrido natural entre Cohniella ascendens y C. brachyphylla (Orchidaceae, Oncidiinae) del oeste de Costa Rica es aquí descrito, ilustrado y caracterizado por caracteres morfológicos y anatómicos. El nuevo híbrido es más similar a C. ascendens pero las flores presentan caracteres intermedios entre sus padres putativos. Cohniella ×francoi se parece a C. ascendens en la inflorescencia semipéndula, la forma del callo, la columna cilíndrica con las alas linear oblongas y la cavidad estigmática obovada, además de varios caracteres anatómicos. Por otro lado, es similar a C. brachyphylla por los lóbulos laterales del labelo oblongos a subcuadrados y extendidos en el mismo plano que el lóbulo central y el disco rectangular con extensiones laterales del callo en los márgenes. Adicionalmente, proporcionamos una tabla de caracteres diagnósticos para el nuevo híbrido y sus padres putativos, una figura comparativa y un mapa detallando las distribuciones geográficas de los tres taxones.
Pseudo-Orbit Data Assimilation. Part II: Assimilation with Imperfect Models
Authors: Du Hailiang , Smith Leonard A.
Published: November 2013

Data assimilation and state estimation for nonlinear models is a challenging task mathematically. Performing this task in real time, as in operational weather forecasting, is even more challenging as the models are imperfect: the mathematical system that generated the observations (if such a thing exists) is not a member of the available model class (i.e., the set of mathematical structures admitted as potential models). To the extent that traditional approaches address structural model error at all, most fail to produce consistent treatments. This results in questionable estimates both of the model state and of its uncertainty. A promising alternative approach is proposed to produce more consistent estimates of the model state and to estimate the (state dependent) model error simultaneously. This alternative consists of pseudo-orbit data assimilation with a stopping criterion. It is argued to be more efficient and more coherent than one alternative variational approach [a version of weak-constraint four-dimensional variational data assimilation (4DVAR)]. Results that demonstrate the pseudo-orbit data assimilation approach can also outperform an ensemble Kalman filter approach are presented. Both comparisons are made in the context of the 18-dimensional Lorenz96 flow and the two-dimensional Ikeda map. Many challenges remain outside the perfect model scenario, both in defining the goals of data assimilation and in achieving high-quality state estimation. The pseudo-orbit data assimilation approach provides a new tool for approaching this open problem.