Low-resolution spectrum of comet C/2004 Q2 (Machholz)

We analysed the spectroscopic data for comet C/2004 Q2 (Machholz), obtained on the Zeiss-600 telescope in Andrushivka Astronomical Observatory on January 29, 2005. The observed spectrum covers a wavelength range 3600-9200 Å with a spectral resolution of 6.2 Å. The molecular-line features of C₂, C₃, CN, NH₂, CH, H₂O⁺, and CH⁺ were found in the spectrum

Modulation of sensory cortical activity by deep brain stimulation in advanced Parkinson's disease

Despite optimal oral drug treatment, about 90% of patients with Parkinson's disease develop motor fluctuation and dyskinesia within 5-10 years from the diagnosis. Moreover, the patients show non-motor symptoms in different sensory domains. Bilateral deep brain stimulation (DBS) applied to the subthalamic nucleus is considered the most effective treatment in advanced Parkinson's disease, and it has been suggested to affect sensorimotor modulation and relate to motor improvement in patients. However, observations on the relationship between sensorimotor activity and clinical improvement have remained sparse. Here, we studied the somatosensory evoked magnetic fields in 13 right-handed patients with advanced Parkinson's disease before and 7 months after stimulator implantation. Somatosensory processing was addressed with magnetoencephalography during alternated median nerve stimulation at both wrists. The strengths and the latencies of the similar to 60-ms responses at the contralateral primary somatosensory cortices were highly variable but detectable and reliably localized in all patients. The response strengths did not differ between preoperative and postoperative DBSON measurements. The change in the response strength between preoperative and postoperative condition in the dominant left hemisphere of our right-handed patients correlated with the alleviation of their motor symptoms (p = .04). However, the result did not survive correction for multiple comparisons. Magnetoencephalography appears an effective tool to explore non-motor effects in patients with Parkinson's disease, and it may help in understanding the neurophysiological basis of DBS. However, the high interindividual variability in the somatosensory responses and poor tolerability of DBSOFF condition warrants larger patient groups and measurements also in non-medicated patients.Peer reviewe

Photometry of distant active comet C/2010 S1 (LINEAR)

We present the results of photometric observations of a dynamically new comet C/2010 S1 (LINEAR), conducted on June 18, 2012. The comet demonstrated a considerable level of physical activity at a heliocentric distance of 6.3 AU. The brightness, measured under a phase angle of 8.9 degrees, was equal to 14.55ᵐ±0.06ᵐ and 14.21ᵐ±0.04ᵐ in V- and R-bands, respectively. The brightness distribution over the coma was found to be inversely proportional to the projected onto the sky plane nucleocentric distance, with a slope of approximately −1. Therefore, the calculated Af ρ parameter, approximately 8400 cm and 8200 cm for V and R filters, respectively, was used to estimate the dust production rate. Assuming a steady outflow of dust particles from the nucleus, the dust production rate was estimated to be between 20 and 60 kg/s, depending on the assumed value of the grain's albedo. The V-R colour index obtained from the near-nucleus region of the coma is in agreement with the solar V-R colour index, and does not indicate significant reddening of the re ected solar radiation in the spectral region of 540-683 nm. Remove selecte

Distant activity of comet C/2002 VQ94 (LINEAR): optical spectrophotometric monitoring between 8.4 and 16.8 au from the Sun

Spectrophotometric monitoring of distant comet C/2002 VQ94 (LINEAR) was performed with the 6-m telescope of SAO RAS and with the 2.5-m Nordic Optical Telescope between 2008 and 2013. During this period the comet was on the outbound segment of its orbit, between heliocentric distances of 8.36 au and 16.84 au. Analysis of the spectra revealed the presence of the CO$^+$ and N$_2^+$ emissions in the cometary coma at a distance of 8.36 au from the Sun. This distance is larger than ionic emissions have been detected in any previous objects. Only continuum, with no traces of emissions, was detected in the spectrum obtained in 2009 when the comet was at a distance of 9.86 au. From the spectra obtained in 2008, average column densities of 2.04$\times$10$^9$ mol cm$^{-2}$ for N$_2^+$ and 3.26$\times$10$^{10}$ mol cm$^{-2}$ for CO$^+$ were measured in the cometary coma. The derived values correspond to N$_2^+$/CO$^+$=0.06 within the projected slit. The parameter, which is used as an indicator of cometary activity, was measured as 2000 cm in 2008, and 800 cm in 2009 and 2011. The values correspond to dust production rates between 10-20 kg s$^{-1}$, 4-6 kg s$^{-1}$ and 3-5 kg s$^{-1}$ at 8.36, 9.86, and 13.40 au respectively. There is an obvious correlation between the decrease of the dust production rate of the nucleus and the disappearance of the emissions in the spectrum of C/2002 VQ94 (LINEAR) at heliocentric distances greater than 9 au. The colors and size of the nucleus of C/2002 VQ94 (LINEAR) were estimated from the images obtained during the late stage at a heliocentric distance of 16.84 au, when the activity had probable ceased. The B-V and V-R colors were estimated to be 1.07$\pm$0.05 and 0.54$\pm$0.03 respectively. The effective nucleus radius of 48$\pm$2 km is in agreement with the previously published results, obtained from the observations of the comet during its early inactive stage.Comment: Accepted for publication in Icarus; 19 pages, 4 tables, 9 figure

Renormalization Scheme Dependence in Variational Approach to QCD

We present a detailed investigation of the renormalization scheme dependence for the Adler 29-function in the framework of the varia­tional approach to QCD