We report a characterization of the multiband flux variability and correlations of the nearby (z=0.031) blazar Markarian 421(Mrk 421) using data from Mets ̈ahovi, Swift, Fermi-LAT, MAGIC, FACT, and ...other collaborations and instruments from 2014November till 2016 June. Mrk 421 did not show any prominent flaring activity, but exhibited periods of historically low activity above 1 TeV (F>1TeV<1.7×10−12ph cm−2s−1) and in the 2–10 keV (X-ray) band (F2−10 keV<3.6×10−11erg cm−2s−1),during which the Swift-BAT data suggest an additional spectral component beyond the regular synchrotron emission. The highest flux variability occurs in X-rays and very high-energy (E>0.1 TeV)γ-rays, which, despite the low activity, show a significant positive correlation with no time lag. The HRkeV and HRTeV show the harder-when-brighter trend observed in many blazars, but the trend flattens at the highest fluxes, which suggests a change in the processes dominating the blazar variability. Enlarging our dataset with data from years 2007 to 2014, we measured a positive correlation between the optical and the GeV emission over a range of about 60 d centred at time lag zero, and a positive correlation between the optical/GeV and the radio emission over a range of about 60 d centred at a time lag of 43+9−6d. This observation is consistent with the radio-bright zone being located about 0.2 parsec downstream from the optical/GeV emission regions of the jet. The flux distributions are better described with a lognormal function in most of the energy bands probed, indicating that the variability in Mrk 421 is likely produced by a multiplicative process.
We report on a multiband variability and correlation study of the TeV blazar Mrk 421 during an exceptional flaring activity observed from 2013 April 11 to 19. The study uses, among others, data from ...GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT), Swift, Nuclear Spectroscopic Telescope Array (NuSTAR), Fermi Large Area Telescope, Very Energetic Radiation Imaging Telescope Array System (VERITAS), and Major Atmospheric Gamma Imaging Cherenkov (MAGIC). The large blazar activity and the 43 hr of simultaneous NuSTAR and MAGIC/VERITAS observations permitted variability studies on 15 minute time bins over three X-ray bands (3-7 keV, 7-30 keV, and 30-80 keV) and three very-high-energy (VHE; >0.1 TeV) gamma-ray bands (0.2-0.4 TeV, 0.4-0.8 TeV, and >0.8 TeV). We detected substantial flux variations on multi-hour and sub-hour timescales in all of the X-ray and VHE gamma-ray bands. The characteristics of the sub-hour flux variations are essentially energy independent, while the multi-hour flux variations can have a strong dependence on the energy of the X-rays and the VHE gamma-rays. The three VHE bands and the three X-ray bands are positively correlated with no time lag, but the strength and characteristics of the correlation change substantially over time and across energy bands. Our findings favor multi-zone scenarios for explaining the achromatic/chromatic variability of the fast/slow components of the light curves, as well as the changes in the flux-flux correlation on day-long timescales. We interpret these results within a magnetic reconnection scenario, where the multi-hour flux variations are dominated by the combined emission from various plasmoids of different sizes and velocities, while the sub-hour flux variations are dominated by the emission from a single small plasmoid moving across the magnetic reconnection layer.
Aims.
The aim of this study is to search for evidence of a common emission engine between radio giant pulses (GPs) and very-high-energy (VHE,
E
> 100 GeV)
γ
-rays from the Crab pulsar.
Methods.
We ...performed 16 h of simultaneous observations of the Crab pulsar at 1.4 GHz with the Effelsberg radio telescope and the Westerbork Synthesis Radio Telescope (WSRT), and at energies above 60 GeV we used the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes. We searched for a statistical correlation between the radio and VHE
γ
-ray emission with search windows of different lengths and different time lags to the arrival times of a radio GP. A dedicated search for an enhancement in the number of VHE
γ
-rays correlated with the occurrence of radio GPs was carried out separately for the P1 and P2 phase ranges, respectively.
Results.
In the radio data sample, 99444 radio GPs were detected. We find no significant correlation between the GPs and VHE photons in any of the search windows. Depending on phase cuts and the chosen search windows, we find upper limits at a 95% confidence level on an increase in VHE
γ
-ray events correlated with radio GPs between 7% and 61% of the average Crab pulsar VHE flux for the P1 and P2 phase ranges, respectively. This puts upper limits on the flux increase during a radio GP between 12% and 2900% of the pulsed VHE flux, depending on the search window duration and phase cuts. This is the most stringent upper limit on a correlation between
γ
-ray emission and radio GPs reported so far.
The Galactic magnetar SGR 1935+2154 was associated with a bright, millisecond-timescale fast radio burst (FRB) which occured in April 2020, during a flaring episode. This was the first time an FRB ...was unequivocally associated with a Galactic source, and the first FRB for which the nature of the emitting source was identified. Moreover, it was the first FRB with a counterpart at another wavelength correlated in time, an atypical, hard X-ray burst, which provides clear evidence for accompanying non-thermal processes. The MAGIC Telescopes are Imaging Air Cherenkov Telescopes (IACTs) sensitive to very-high-energy (VHE, E>100 GeV) gamma rays. Located at the center of the camera lies the MAGIC Central pixel, a single fully-modified photosensor-toreadout chain to measure millisecond-duration optical signals, displaying a maximum sensitivity at a wavelength of 350 nm. This allows MAGIC to operate simultaneously both as a VHE gammaray and a fast optical telescope. The MAGIC telescopes have monitored SGR 1935+2154 in a multiwavelength campaign involving X-ray, radio and optical facilities. In this contribution, we will show the results on the search for the VHE counterpart of the first SGR-FRB source in this multiwavelength context, as well as the search for fast optical bursts with the MAGIC Central Pixel.
Extreme high-frequency-peaked BL Lac objects (EHBLs) are blazars that exhibit extremely energetic synchrotron emission. They also feature nonthermal gamma-ray emission whose peak lies in the very ...high-energy (VHE, E > 100 GeV) range, and in some sources exceeds 1 TeV: this is the case for hard-TeV EHBLs such as 1ES 0229+200. With the aim of increasing the EHBL population, 10 targets were observed with the MAGIC telescopes from 2010 to 2017, for a total of 265 hr of good-quality data. The data were complemented by coordinated Swift observations. The X-ray data analysis confirms that all but two sources are EHBLs. The sources show only a modest variability and a harder-when-brighter behavior, typical for this class of objects. At VHE gamma-rays, three new sources were detected and a hint of a signal was found for another new source. In each case, the intrinsic spectrum is compatible with the hypothesis of a hard-TeV nature of these EHBLs. The broadband spectral energy distributions (SEDs) of all sources are built and modeled in the framework of a single-zone, purely leptonic model. The VHE gamma-ray-detected sources were also interpreted with a spine-layer model and a proton synchrotron model. The three models provide a good description of the SEDs. However, the resulting parameters differ substantially in the three scenarios, in particular the magnetization parameter. This work presents the first mini catalog of VHE gamma-ray and multiwavelength observations of EHBLs.
The aim of this study was to determine the prevalence of diabetic peripheral neuropathy (DPN) and neuropathic pain in diabetic patients attending university outpatient clinics in Turkey. In this ...multicenter cross-sectional study, neurologic examinations and nerve conduction studies along with clinical diabetic neuropathy score, and Leeds Assessment of Neuropathic Symptoms and Signs pain scale were performed on 1,113 patients (46.2% male) from 14 centers. Prevalence of DPN determined only by clinical examination was 40.4% and increased to 62.2%, by combining nerve conduction studies with clinical examination. According to Leeds Assessment of Neuropathic Symptoms and Signs scores, neuropathic pain prevalence was 16.0% in those who reported pain. Poor glycemic control, retinopathy, microalbuminuria, hyperlipidemia, diabetic foot, and foot amputation were more commonly observed in patients with DPN. Clinical DPN affected 40.4% of diabetic patients, and neuropathic pain prevalence in diabetic patient population was 14.0%. Clinical examinations and nerve conduction studies are important components for early detection and accurate diagnosis of DPN and painful DPN.
A novel phase-shift control of a semibridgeless active rectifier (S-BAR) is investigated in order to utilize the S-BAR in wireless energy transfer applications. The standard receiver-side rectifier ...topology is developed by replacing rectifier lower diodes with synchronous switches controlled by a phase-shifted PWM signal. Theoretical and simulation results show that with the proposed control technique, the output quantities can be regulated without communication between the receiver and transmitter. To confirm the performance of the proposed converter and control, experimental results are provided using 8-, 15-, and 23-cm air gap coreless transformer which has dimension of 76 cm × 76 cm, with 120-V input and the output power range of 0 to 1kW with a maximum efficiency of 94.4%.
Abstract Background Pregabalin has a similar pharmacologic profile to that of its developmental predecessor gabapentin but has shown greater analgesic activity in rodent models of neuropathic pain. ...Objective The objective of the study was to compare the effects of 2 different doses of pregabalin and placebo on postoperative pain and morphine consumption. Methods Ninety patients who underwent abdominal hysterectomy were included in the study and randomly divided into 3 groups in a doubled-blinded manner. They were given 150 mg of pregabalin (group P300, n = 30), 300 mg of pregabalin (group P600, n = 30), or placebo capsules (group C, n = 30) 4 hours before the induction of anesthesia; they received a second dose of the drug 12 hours postoperatively. Morphine consumption, nausea, and vomiting, visual analogue scale-pain intensity (VAS-PI), sedation scores, and dissatisfaction scores were recorded in the postanesthesia care unit (PACU) and at 2, 4, 6, and 24 hours after operation. Results Morphine consumption at 24 hours was 40.80 (3.42) mg, 33.79 (5.77) mg, and 46.97 (6.67) mg in groups P300, P600, and C, respectively ( P < 0.001). VAS-PI scores at movement and at rest in the PACU and at 2, 4, and 6 hours decreased in group P600 ( P < 0.01). In the PACU and at 2, 4, and 6 hours, the sedation scores were increased in group P600 compared with the scores in group C ( P < 0.001, P < 0.001, P = 0.01, P = 0.006, respectively). Patient satisfaction was higher in group P600 than in group C for all time points ( P < 0.001, P < 0.001, P < 0.001, P = 0.001, P < 0.001, respectively). There were no statistically significant differences between the groups for side effects such as nausea, vomiting, and dizziness ( P = 0.58). Conclusions Pregabalin at a total dose of 600 mg, administered before operation and at 12 hours postoperatively after abdominal hysterectomy, reduced morphine consumption and pain intensity and increased patient satisfaction. No significant differences in side effects were observed between the study groups.
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