Empirical multi-wavelength prediction method for very high energy gamma-ray emitting BL Lacs

Aim: We have collected the most complete multi-wavelength ($6.0 - 6.0 \times 10^{-18} cm$) dataset of very high energy (VHE) $\gamma$-ray emitting (TeV) BL Lacs, which are the most numerous extragalactic VHE sources. Using significant correlations between different bands, we aim to identify the best TeV BL Lac candidates that can be discovered by the current and next generation of imaging air Cherenkov telescopes. Methods: We formed five datasets from lower energy data, i.e. radio, mid-infrared, optical, X-rays, and GeV $\gamma$-ray, and five VHE $\gamma$-ray datasets to perform a correlation study between different bands and to construct the prediction method. The low energy datasets were averaged for individual sources, while the VHE $\gamma$-ray data were divided into subsets according to the flux state of the source. We then looked for significant correlations and determined their best-fit parameters. Using the best-fit parameters we predicted the level of VHE $\gamma$-ray flux for a sample of 182 BL Lacs, which have not been detected at TeV energies. We identified the most promising TeV BL Lac candidates based on the predicted VHE $\gamma$-ray flux for each source. Results: We found 14 significant correlations between radio, mid-infrared, optical, $\gamma$-ray, and VHE $\gamma$-ray bands. The correlation between optical and VHE $\gamma$-ray luminosity is established for the first time. We attribute this to the more complete sample and more accurate handling of host galaxy flux in our work. We found nine BL Lac candidates whose predicted VHE $\gamma$-ray flux is high enough for detection in less than 25 hours with current imaging air Cherenkov telescopes.Comment: 10 pages, 2 figures, 4 Table

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

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

A case study on biomass burning aerosols: effects on aerosol optical properties and surface radiation levels

In spring 2006, biomass burning aerosols from eastern Europe were transported extensively to Finland, and to other parts of northern Europe. They were observed as far as in the European Arctic. In the first part of this paper, temporal and spatial evolution and transport of these biomass burning aerosols are monitored with MODIS retrieved aerosol optical depth (AOD) imagery at visible wavelengths (0.55 μm). Comparison of MODIS and AERONET AOD is conducted at Tõravere, Estonia. Then trajectory analyses, as well as MODIS Fire Mapper products are used to better understand the type and origin of the air masses. During the studied four-week period AOD values ranged from near zero up to 1.2 at 0.55 μm and the linear correlation between MODIS and AERONET was very high (~0.97). Temporal variability observed within this four-week period was also rather well explained by the trajectory analysis in conjunction with the fire detections produced by the MODIS Rapid Response System. In the second part of our study, the surface measurements of global and UV radiation at Jokioinen, Finland are used to study the effect of this haze episode on the levels of surface radiation. We found reductions up to 35% in noon-time surface UV irradiance (at 340 nm) as compared to typical aerosol conditions. For global (total solar) radiation, the reduction was always smaller, in line with the expected wavelength dependence of the aerosol effect

A case study on long-range transported aerosols of biomass burning: effects on aerosol optical properties and surface radiation levels

International audienceIn spring 2006, biomass burning aerosols from eastern Europe were transported extensively to Finland, and to other parts of northern Europe. They were observed as far as in the European Arctic. In the first part of this paper, temporal and spatial evolution and transport of these biomass burning aerosols are monitored with MODIS retrieved aerosol optical depth (AOD) imagery at visible wavelengths (0.55 ?m). Comparison of MODIS and AERONET AOD is conducted at Tõravere, Estonia. Then trajectory analyses, as well as MODIS Fire Mapper products are used to better understand the type and origin of the air masses. During the studied four-week period AOD values ranged from near zero up to 1.2 at 0.55 ?m and the linear correlation between MODIS and AERONET was very high (~0.97). Temporal variability observed within this four-week period was also rather well explained by the trajectory analysis in conjunction with the fire detections produced by the MODIS Rapid Response System. In the second part of our study, the surface measurements of global and UV radiation at Jokioinen, Finland are used to study the effect of this haze episode on the levels of surface radiation. We found reductions up to 35% in surface UV irradiance (at 340 nm) as compared to typical aerosol conditions. For global (total solar) radiation, the reduction was always smaller, in line with the expected wavelength dependence of the aerosol effect

Multiwavelength observation from radio through very-high-energy Gamma-ray of OJ 287 during the 12-year cycle flare in 2007

We performed simultaneous multiwavelength observations of OJ 287 with the Nobeyama Millimeter Array for radio, the KANATA telescope and the KVA telescope for optical, the Suzaku satellite for X-ray and the MAGIC telescope for very high energy (VHE) gamma-ray in 2007. The observations were conducted for a quiescent state in April and in a flaring state in November-December. We clearly observed increase of fluxes from radio to X-ray bands during the flaring state while MAGIC could not detect significant VHE gamma-ray emission from the source. We could derive an upper limit (95% confidence level) of 1.7% of the Crab Nebula flux above 150 GeV from about 41.2 hours of the MAGIC observation. A simple SSC model suggests that the observed flaring activity could be caused by evolutions in the distribution of the electron population rather than changes of the magnetic field strength or Doppler beaming factor in the jet.Comment: Contribution to the 31st ICRC, Lodz, Poland, July 200

Radiocarpal Injuries : Cone Beam Computed Tomography Arthrography, Magnetic Resonance Arthrography, and Arthroscopic Correlation among 21 Patients

Background and Aims: Patients with acute or chronic wrist pain often undergo wrist arthroscopy for evaluation of chondral and ligamentous abnormalities. The purpose of this study was to compare findings of wrist arthroscopy with cone beam computed tomography arthrography and magnetic resonance arthrography. Materials and Methods: Altogether, 21 patients with wrist pain underwent cone beam computed tomography arthrography, magnetic resonance arthrography, and wrist arthroscopy. Chondral surfaces of the scaphoid, lunate, and radius facing the scaphoid and lunate were evaluated. The scapholunate ligament, the lunotriquetral ligament, and the triangular fibrocartilage complex were classified as either intact or torn. Sensitivity, specificity, positive and negative predictive values, and accuracy with 95% confidence intervals were assessed. Results: For chondral lesions (n=10), cone beam computed tomography arthrograms showed slightly higher specificity than magnetic resonance arthrography. The sensitivity of cone beam computed tomography arthrography was also better for these lesions, except for those on the chondral surface of the lunate. For triangular fibrocartilage complex injuries (n=9), cone beam computed tomography arthrography showed a better specificity and sensitivity than magnetic resonance arthrography. For ligamentous injuries (n=6), cone beam computed tomography arthrograms were more sensitive, but less specific than magnetic resonance arthrography images. However, the number of lesions was very small and the 95% confidence intervals are overlapping. Conclusion: Cone beam computed tomography is an emerging imaging modality that offers several advantages over computed tomography and magnetic resonance imaging. Its usefulness particularly in ligamentous injuries should be further explored in a larger study. Cone beam computed tomography arthrography seems to offer similar sensitivity, specificity, and accuracy compared to magnetic resonance arthrography and therefore serves as a valuable option in evaluating patients with wrist pain.Peer reviewe

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