1,345 research outputs found
Redshift constraints for RGB 0136+391 and PKS 0735+178 from deep optical imaging
We present the results of deep I-band imaging of two BL Lacerate objects, RGB
0136+391 and PKS 0735+178, during an epoch when the optical nucleus was in a
faint state in both targets. In PKS 0735+178 we find a significant excess over
a point source, which, if fitted by the de Vaucouleurs model, corresponds to a
galaxy with I = 18.64 +- 0.11 and r_eff = 1.8 +- 0.4 arcsec. Interpreting this
galaxy as the host galaxy of PKS 0735+178 we derive z = 0.45 +- 0.06 using the
host galaxy as a "standard candle". We also discuss the immediate optical
environment of PKS 0735+178 and the identity of the MgII absorber at z = 0.424.
Despite of the optimally chosen epoch and deep imaging we find the surface
brightness profile of RGB 0136+391 to be consistent with a point source. By
determining a lower limit for the host galaxy brightness by simulations, we
derive z > 0.40 for this target.Comment: 6 pages, 5 figures, accepted for publication in Astronomy &
Astrophysic
Tubomanometry correlations with patient characteristics and other diagnostic tests of Eustachian tube dysfunction : a cohort study of 432 ears
Objectives Currently, there is no consensus regarding the best protocol for diagnosing Eustachian tube dysfunction (ETD). We aimed to evaluate how patient characteristics affect tubomanometry (TMM) results. If an association between patient characteristics and TMM results exists, this should be considered in TMM interpretation. We also wanted to study if TMM correlates with other diagnostic tools of ETD. Methods A retrospective chart review was conducted on all patients with TMM results available from November 2011 to October 2020 at a tertiary referral center, including 432 ears from 219 patients. An association between diagnostic tests and patient characteristics was assessed using regression models. Spearman's rank correlation was used to analyze correlations between diagnostic tests. Results None of the studied patient characteristics (age, gender, body mass index, smoking, sinonasal disease) was associated with TMM results except for pollen allergy (OR 1.74, 95% CI 1.15-2.63, P = 0.009). TMM results correlated with Valsalva maneuver performance (P < 0.001, rho = 0.31) and otomicroscopic signs of inadequate middle ear ventilation (P < 0.001, rho = 0.28). The Eustachian tube dysfunction questionnaire-7 (ETDQ-7) score did not correlate with any diagnostic method. Conclusions TMM results are unaffected by patient characteristics other than pollen allergy. Thus, TMM may be used in ETD diagnostics in a wide variety of patients with straightforward interpretation. TMM correlates with other diagnostic tests studied but not with ETDQ-7. ETDQ-7 does not seem to correlate with other diagnostic tests and appears nonspecific in ETD diagnostics.Peer reviewe
MAGIC observations of Mkn 421 in 2008, and related optical/X-ray/TeV MWL study
The HBL-type blazar Markarian 421 is one of the brightest TeV gamma-ray
sources of the Northern sky. From December 2007 until June 2008 it was
intensively observed in the VHE (E>100 GeV) band by the MAGIC gamma-ray
telescope. The source showed intense and prolonged activity during the whole
period. In some nights the integral flux rose up to 3.6 Crab units (E>200 GeV).
Intra-night rapid flux variations were observed. We compared the optical (KVA)
and X-ray (RXTE-ASM, Swift-XRT) data with the MAGIC VHE data, investigating the
correlations between different energy bands.Comment: 4 pages,4figures, Contribution to the 31st ICRC, Lodz, Poland, July
200
Changes in the surface energy budget after fire in boreal ecosystems of interior Alaska: An annual perspective
Understanding links between the disturbance regime and regional climate in boreal regions requires observations of the surface energy budget from ecosystems in various stages of secondary succession. While several studies have characterized fire‐induced differences in surface energy fluxes from boreal ecosystems during summer months, much less is known about these differences over the full annual cycle. Here we measured components of the surface energy budget (including both radiative and turbulent fluxes) at three sites from a fire chronosequence in interior Alaska for a 1‐year period. Our sites consisted of large burn scars resulting from fires in 1999, 1987, and ∼1920 (hereinafter referred to as the 3‐, 15‐, and 80‐year sites, respectively). Vegetation cover consisted primarily of bunch grasses at the 3‐year site, aspen and willow at the 15‐year site, and black spruce at the 80‐year site. Annual net radiation declined by 31% (17 W m^(−2)) for both the 3‐ and the 15‐year sites as compared with the 80‐year site (which had an annual mean of 55 W m^(−2)). Annual sensible heat fluxes were reduced by an even greater amount, by 55% at the 3‐year site and by 52% at the 15‐year site as compared with the 80‐year site (which had an annual mean of 21 W m^(−2)). Absolute differences between the postfire ecosystems and the mature black spruce forest for both net radiation and sensible heat fluxes were greatest during spring (because of differences in snow cover and surface albedo), substantial during summer and winter, and relatively small during fall. Fire‐induced disturbance also initially reduced annual evapotranspiration (ET). Annual ET decreased by 33% (99 mm yr^(−1)) at the 3‐year site as compared with the 80‐year site (which had an annual flux of 301 mm yr^(−1)). Annual ET at the 15‐year site (283 mm yr^(−1)) was approximately the same as that from the 80‐year site, even though the 15‐year site had substantially higher ET during July. Our study suggests that differences in annual ET between deciduous and conifer stands may be smaller than that inferred solely from summer observations. This study provides a direct means to validate land surface processes in global climate models attempting to capture vegetation‐climate feedbacks in northern terrestrial regions
A Kpc-scale Radio Polarization Study of PG BL Lacs with the uGMRT
We present here uGMRT band 4 (~650MHz) polarization images of 8 BL~Lac
objects belonging to the Palomar-Green (PG) `blazar' sample. A large fraction
of the sources (~63%) reveal core-halo radio structures with most of the
polarization detected in the inner core-jet regions. PG1101+385 and PG2254+075
exhibit a `spine-sheath structure' in polarization. The core-halo and
`spine-sheath' structures are consistent with the Unified Scheme suggestion
that BL~Lacs are the pole-on beamed counterparts of Fanaroff-Riley (FR) type I
radio galaxies. PG1418+546 and PG0851+203 (OJ287) show the presence of terminal
hotspots similar to FR type II radio galaxies. They were also found to be
low-spectrally peaked BL Lacs, supportive of the `blazar envelope' scenario for
BL~Lacs and quasars. Fractional polarization ranges from 1-13% in the cores and
2-26% in the inner jets/lobes of the sample BL Lacs. Compared to the varied
radio morphology of quasars from the PG `blazar' sample, the BL~Lacs appear to
be less diverse. A comparison of the inferred core magnetic (B-) field
structures on arcsec- (kpc-) scales w.r.t. the Very Long Baseline
Interferometry (VLBI) jet direction does not reveal any preferred orientation,
suggesting that if large-scale ordered B-fields exist, they do so on scales
smaller than probed by the current observations. However, the presence of
polarized emission on arcsec-scales suggests that any mixing of thermal plasma
with the synchrotron emitting plasma is insufficient to fully depolarize the
emission via the internal depolarization process.Comment: 17 pages; 12 figures; MNRAS accepte
Tuning the polarization states of optical spots at the nanoscale on the poincar´e sphere using a plasmonic nanoantenna
It is shown that the polarization states of optical spots at the nanoscale can be manipulated to various points on the Poincar´e sphere using a plasmonic nanoantenna. Linearly, circularly, and elliptically polarized near-field optical spots at the nanoscale are achieved with various polarization states on the Poincar´e sphere using a plasmonic nanoantenna. A novel plasmonic nanoantenna is illuminated with diffraction-limited linearly polarized light. It is demonstrated
that the plasmonic resonances of perpendicular and longitudinal components of the nanoantenna and the angle of incident polarization can be tuned to obtain optical spots beyond the diffraction limit with a desired polarization and handedness
Sinus Barotraumas in Commercial Aircrew
BACKGROUND: Sinus barotraumas are a common condition in aviation medicine, sometimes compromising flight safety and even permanently grounding aircrew. Considering this and the ever-increasing amount of commercial aviation, a thorough examination is required. METHODS: In this survey study, an anonymous, electronic questionnaire was distributed to commercial aircrew of the three major commercial airlines operating in Finland (N = 3799), covering 93% of the target population (i.e., all commercial aircrew operating in Finland, N = 4083). Primary outcomes were self-reported prevalence, clinical characteristics, and health and occupational effects of sinus barotraumas in flight. Secondary outcomes were adjusted odds ratios (OR) for frequency of sinus barotraumas with respect to possible risk factors. RESULTS: Response rate was 47% (N = 1789/3799), with 61% (N = 1088) of the respondents having experienced sinus barotraumas in flight. Of those affected, 59% had used medications, 18% had undergone surgical procedures, and 53% had been on sick leave due to sinus barotraumas (38% during the last year) in flight. Factors associated with sinus barotraumas were female sex [OR, 2.47; 95% confidence interval (CI) 1.35-4.50] and a high number of upper respiratory tract infections (>= 3 vs.Peer reviewe
Middle Ear Barotraumas in Commercial Aircrew
BACKGROUND: Middle ear (ME) barotraumas are the most common condition in aviation medicine, sometimes seriously compromising flight safety. Considering this and the ever-increasing amount of commercial aviation, a detailed overview is warranted. METHODS: In this survey study, an anonymous, electronic questionnaire was distributed to commercial aircrew of the three major commercial airlines operating in Finland (N = 3799), covering 93% of the target population (i.e., all commercial aircrew operating in Finland, N = 4083). Primary outcomes were self-reported prevalence, clinical characteristics, and health and occupational effects of ME barotraumas in flight. Secondary outcomes were adjusted odds ratios (OR) for frequency of ME barotraumas with respect to possible risk factors. RESULTS: Response rate was 47% (N = 1789/3799), with 85% (N 1516) having experienced ME barotraumas in flight. Of those affected, 60% had used medications, 5% had undergone surgical procedures, and 48% had been on sick leave due to ME barotraumas (40% during the last year). Factors associated with ME barotraumas included a high number of upper respiratory tract infections [>= 3 URTIs/yr vs. 0 LIRTIs/yr: OR, 9.02; 95% confidence interval (CI) 3.99-20.39] and poor subjective performance in Valsalva ("occasionally" vs."a lways" successful: OR, 7.84; 95% CI 3.97-15.51) and Toynbee ("occasionally" vs."always" successful: OR, 9.06; 95% CI 2.67-30.78) maneuvers. CONCLUSION: ME barotraumas were reported by 85% of commercial aircrew.They lead to an increased need for medications, otorhinolaryngology-related surgical procedures, and sickness absence from flight duty. Possible risk factors include a high number of URTIs and poor performance in pressure equalization maneuvers.Peer reviewe
All-optical reversible switching of local magnetization
The authors demonstrate all-optical reversible switching of the magnetization direction in a uniformly magnetized ferrite-garnet film. The magnetization is switched by locally heating the film with a pulsed laser beam. The direction to which the magnetization flips is controlled by two parameters, the beam diameter and the pulse energy, and not by the direction of the external magnetic field. In the experiments, neither the magnitude nor the direction of the external magnetic field is changed. The results of this work illustrate the richness of optical methods to locally control the properties of magnetic materials and suggest all-optical device applications.Peer reviewe
A significant hardening and rising shape detected in the MeV/GeV nuFnu spectrum from the recently-discovered very-high-energy blazar S4 0954+65 during the bright optical flare in 2015 February
We report on Fermi Large Area Telescope (LAT) and multi-wavelength results on
the recently-discovered very-high-energy (VHE, 100 GeV) blazar S4 0954+65
() during an exceptionally bright optical flare in 2015 February.
During the time period (2015 February, 13/14, or MJD 57067) when the MAGIC
telescope detected VHE -ray emission from the source, the Fermi-LAT
data indicated a significant spectral hardening at GeV energies, with a
power-law photon index of ---compared with the 3FGL value
(averaged over four years of observation) of . In contrast,
Swift/XRT data showed a softening of the X-ray spectrum, with a photon index of
(compared with averaged during the flare from
MJD 57066 to 57077), possibly indicating a modest contribution of synchrotron
photons by the highest-energy electrons superposed on the inverse Compton
component. Fitting of the quasi-simultaneous ( day) broadband spectrum with
a one-zone synchrotron plus inverse-Compton model revealed that GeV/TeV
emission could be produced by inverse-Compton scattering of external photons
from the dust torus. We emphasize that a flaring blazar showing high flux of
photons cm s ( 100 MeV) and a
hard spectral index of detected by Fermi-LAT on daily
time scales is a promising target for TeV follow-up by ground-based Cherenkov
telescopes to discover high-redshift blazars, investigate their temporal
variability and spectral features in the VHE band, and also constrain the
intensity of the extragalactic background light.Comment: 15 pages, 3 figures, 2 tables. Accepted by PAS
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