THE FUNDAMENTAL PLANE FOR RADIO MAGNETARS Rea, Nanda; Pons, Jose A; Torres, Diego F ...
Astrophysical journal. Letters,
03/2012, Letnik:
748, Številka:
1
Journal Article
Recenzirano
Odprti dostop
High magnetic fields are a distinguishing feature of neutron stars and the existence of sources (the soft gamma repeaters, SGRs, and the anomalous X-ray pulsars) hosting an ultramagnetized neutron ...star (or magnetar) has been recognized in the past few decades. Magnetars are believed to be powered by magnetic energy and not by rotation, as with normal radio pulsars. Until recently, the radio quietness and magnetic fields typically above the quantum critical value (B sub(Q) Asymptotically = to 4.4 x 10 super(13) G) were among the characterizing properties of magnetars. The recent discovery of radio-pulsed emission from a few of them, and of a low dipolar magnetic field SGR, weakened further the idea of a clean separation between normal pulsars and magnetars. In this Letter, we show that radio emission from magnetars might be powered by rotational energy, similarly to what occurs in normal radio pulsars. The peculiar characteristics of magnetars radio emission should be traced in the complex magnetic geometry of these sources. Furthermore, we propose that magnetar radio activity or inactivity can be predicted from the knowledge of the star's rotational period, its time derivative, and the quiescent X-ray luminosity.
The popular outer gap model of magnetospheric emission from pulsars has been widely applied to explain the properties observed in gamma -rays. However, its quantitative predictions rely on a number ...of approximations and assumptions that are usually overlooked. Here we examine them, reviewing the main ingredients entering the model, evaluating their range of uncertainties. Usually, in the quantitative applications of the model, key parameters like the radius of curvature and the energies of the interacting photons are taken to be a fixed, single value. Instead, here we explore their realistic ranges, and the impact of these on the consistency of the model itself. We conclude that the popular evaluation of the transfield size of the gap as a function of period and period derivative, is unreliable and affected by a huge dispersion. Last, the exploration of the possible values for the radius of curvature, the local magnetic field and other quantities deserve more attention for quantitative applications of the outer gap model, like the calculation of gamma -ray spectra, which is the subject of an accompanying paper.
Objective
To determine the differences between clinical, manometric, and neuroimmunological profile of esophagogastric junction outflow obstruction (EGJOO) and achalasia patients.
Methods
Seven EGJOO ...and 27 achalasia patients were enrolled in a blind cross‐sectional study. Peripheral blood (PB) of 10 healthy donors and 10 lower esophageal sphincter (LES) muscle biopsies from organ transplant donors were included as controls. The presence of ganglion cells, cells of Cajal, Th22/Th7/Th2/Th1/Tregs/Bregs/pDCregs in tissue, and PB was assessed by immunohistochemistry and flow cytometry. Serum concentration of IL‐22/IL‐17A/IL‐17F/IL‐4/IFN‐γ/IL‐1β/IL‐6/IL‐23/IL‐33/TNF‐α/IL‐10 was determined using bioplex plates. ANAs and antineuronal antibodies were evaluated by immunofluorescence and Western blot.
Key Results
EGJOO and achalasia patients had lower ganglion cells and cells of Cajal percentage vs. controls, while fibrosis was present only in achalasia patients. EGJOO and controls had lower cell percentage of Th22/Th17/Th2 vs. achalasia. EGJOO tissue had lower Th1/Treg cell number vs. achalasia, but higher levels vs. control group. Bregs and pDCregs percentage was higher in EGJOO vs. control group. Percentage of PB subpopulations in EGJOO was not significantly different from control group. Serum cytokine levels were higher for IL‐1β/IL‐6/TNF‐α, while IL‐17A levels were lower in EGJOO vs. achalasia and control group. EGJOO group was negative for ANAs, while in achalasia group, 54% were positive. GAD65 and PNMa/Ta2 antibodies were present in achalasia, whereas Yo and recoverin were positive in EGJOO group.
Conclusions and Inferences
Although EGJOO shares some clinical characteristics with achalasia, the neuroimmunological profile is completely different, suggesting that EGJOO might be a different entity.
Hypothetical model of EGJOO neuroimmunological pathophysiology.
We report on a multi-wavelength study of the unclassified X-ray source CXOU J110926.4−650224 (J1109). We identified the optical counterpart as a blue star with a magnitude of ∼20.1 (3300–10500 Å). ...The optical emission was variable on timescales from hundreds to thousands of seconds. The spectrum showed prominent emission lines with variable profiles at different epochs. Simultaneous XMM-Newton and NuSTAR observations revealed a bimodal distribution of the X-ray count rates on timescales as short as tens of seconds, as well as sporadic flaring activity. The average broad-band (0.3–79 keV) spectrum was adequately described by an absorbed power law model with photon index of Γ = 1.63 ± 0.01 (at 1σ c.l.), and the X-ray luminosity was (2.16 ± 0.04) × 1034 erg s−1 for a distance of 4 kpc. Based on observations with different instruments, the X-ray luminosity has remained relatively steady over the past ∼15 years. J1109 is spatially associated with the gamma-ray source FL8Y J1109.8−6500, which was detected with Fermi at an average luminosity of (1.5 ± 0.2) × 1034 erg s−1 (assuming the distance of J1109) over the 0.1–300 GeV energy band between 2008 and 2016. The source was undetected during ATCA radio observations that were simultaneous with NuSTAR, down to a 3σ flux upper limit of 18 μJy beam−1 (at 7.25 GHz). We show that the phenomenological properties of J1109 point to a binary transitional pulsar candidate currently in a sub-luminous accretion disk state, and that the upper limits derived for the radio emission are consistent with the expected radio luminosity for accreting neutron stars at similar X-ray luminosities.
Biodiesel is the best candidate for fuel oil replacement, and to obtain it, heterogeneous catalysts offer large advantages: they can be separated from the product and reused. This work reviews a ...novel one-step synthesis of CaO-ZnO catalytic particles suitable for biodiesel production. The catalyst is synthesized using an original simple method that involves mixing of ZnO with CaCO3 and subsequent calcination. The CaO-ZnO microparticles obtained present an average size of 2 μm. This material shows the characteristic crystallographic cubic structure of CaO and the hexagonal phase of ZnO. The temperature-programmed reduction experiment evidences an interaction between CaO and ZnO. Moreover, the infrared spectroscopy shows typical bands of these compounds. The catalyst shows high biodiesel yield, up to 73% in the first cycle and 64% in the second one. In this work, the synthesis of an efficient CaO-ZnO catalyst with a huge potential is revealed, which could be an economic alternative to produce biodiesel.
Based on a theoretical selection of pulsars as candidates for detection at X-ray energies, we present an analysis of archival X-ray observations performed with Chandra and XMM-Newton of PSR ...J1747-2958 (the pulsar in the "Mouse" nebula), PSR J2021+3651 (the pulsar in the "Dragonfly" nebula), and PSR J1826-1256. X-ray pulsations from PSR J1747-2958 and PSR J1826-1256 are detected for the first time, and a previously reported hint of an X-ray pulsation from PSR J2021+3651 is confirmed with a higher significance. We analyze these pulsars' spectra in regard to the theoretically predicted energy distribution, finding a remarkable agreement, and provide here a refined calculation of the model parameters taking into account the newly derived X-ray spectral data.
Abstract
The unidentified TeV source MGRO J1908+06, with emission extending from hundreds of GeV to beyond 100 TeV, is one of the most intriguing sources in the Galactic plane. MGRO J1908+06 ...spatially associates with an IceCube hotspot of neutrino emission. Although the hotspot is not significant yet, this suggests a possible hadronic origin of the observed gamma-ray radiation. Here we describe a multiwavelength analysis on MGRO J1908+06 to determine its nature. We identify, for the first time, an extended GeV source as the counterpart of MGRO J1908 + 06, discovering possibly associated molecular clouds (MCs). The GeV spectrum shows two well-differentiated components: a soft spectral component below ∼10 GeV, and a hard one (Γ ∼ 1.6) above these energies. The lower-energy part is likely associated with the dense MCs surrounding the supernova remnant (SNR) G40.5−0.5, whereas the higher-energy component, which connects smoothly with the spectrum observed in TeV range, resembles the inverse Compton emission observed in relic pulsar wind nebulae. This simple scenario seems to describe the data satisfactorily, but raises questions about the interpretation of the emission at hundreds of TeV. In this scenario, no detectable neutrino flux would be expected.
We report the detection of GeV gamma -ray emission from the molecular cloud complex that surrounds the supernova remnant (SNR) W44 using the Large Area Telescope on board Fermi. While the previously ...reported gamma -ray emission from SNR W44 is likely to arise from the dense radio-emitting filaments within the remnant, the gamma -ray emission that appears to come from the surrounding molecular cloud complex can be ascribed to the cosmic rays (CRs) that have escaped from W44. The non-detection of synchrotron radio emission associated with the molecular cloud complex suggests the decay of pi super(0) mesons produced in hadronic collisions as the gamma -ray emission mechanism. The total kinetic energy channeled into the escaping CRs is estimated to be W sub(esc) ~ (0.3-3) x 10 super(50) erg, in broad agreement with the conjecture that SNRs are the main sources of Galactic CRs.
Fibrosing diseases are causes of morbidity and mortality around the world, and they are characterized by excessive extracellular matrix (ECM) accumulation. The bHLH transcription factor scleraxis ...(SCX) regulates the synthesis of ECM proteins in heart fibrosis. SCX expression was evaluated in lung fibroblasts and tissue derived from fibrotic disease patients and healthy controls. We also measured SCX in sera from 57 healthy controls, and 56 Idiopathic Pulmonary Fibrosis (IPF), 40 Hypersensitivity Pneumonitis (HP), and 100 Systemic Sclerosis (SSc) patients. We report high SCX expression in fibroblasts and tissue from IPF patients versus controls. High SCX-serum levels were observed in IPF (0.663 ± 0.559 ng/mL,
< 0.01) and SSc (0.611 ± 0.296 ng/mL,
< 0.001), versus controls (0.351 ± 0.207 ng/mL) and HP (0.323 ± 0.323 ng/mL). Serum levels of the SCX heterodimerization partner, TCF3, did not associate with fibrotic illness. IPF patients with severely affected respiratory capacities and late-stage SSc patients presenting anti-topoisomerase I antibodies and interstitial lung disease showed the highest SCX-serum levels. SCX gain-of-function induced the expression of alpha-smooth muscle actin (α-SMA/ACTA2) in fibroblasts when co-overexpressed with TCF3. As late and severe stages of the fibrotic processes correlated with high circulating SCX, we postulate it as a candidate biomarker of fibrosis and a potential therapeutic target.
The continuous relationship between blood pressure (BP) and cardiovascular events makes the distinction between elevated BP and hypertension based on arbitrary cut-off values for BP. Even mild BP ...elevations manifesting as high-normal BP have been associated with cardiovascular risk. We hypothesize that persistent elevated BP increases atherosclerotic plaque development. To evaluate this causal link, we developed a new mouse model of elevated BP based on adeno-associated virus (AAV) gene transfer. We constructed AAV vectors to support transfer of the
and
genes. A single injection of AAV-
/
(10
total viral particles) induced sustained systolic BP increase (130 ± 20 mmHg, vs. 110 ± 15 mmHg in controls;
= 0.05). In
mice, AAV-induced mild BP elevation caused larger atherosclerotic lesions evaluated by histology (10-fold increase vs. normotensive controls). In this preclinical model, atheroma plaques development was attenuated by BP control with a calcium channel blocker, indicating that a small increase in BP within a physiological range has a substantial impact on plaque development in a preclinical model of atherosclerosis. These data support that non-optimal BP represents a risk for atherosclerosis development. Earlier intervention in elevated BP may prevent or delay morbidity and mortality associated with atherosclerosis.
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