A Double-Mode RR Lyrae Star with a Strong Fundamental Mode Component

NSVS 5222076, a thirteenth magnitude star in the Northern Sky Variability Survey, was identified by Oaster as a possible new double-mode RR Lyrae star. We confirm the double-mode nature of NSVS 5222076, supplementing the survey data with new V band photometry. NSVS 5222076 has a fundamental mode period of 0.4940 day and a first overtone period of 0.3668 day. Its fundamental mode light curve has an amplitude twice as large as that of the first overtone mode, a ratio very rarely seen. Data from the literature are used to discuss the location in the Petersen diagram of double-mode RR Lyrae stars having strong fundamental mode pulsation. Such stars tend to occur toward the short period end of the Petersen diagram, and NSVS 5222976 is no exception to this rule.Comment: 14 pages, 4 figures, To be published in the March, 2006, issue of PAS

1318 New Variable Stars in a 0.25 Square Degree Region of the Galactic Plane

We have conducted a deep photometric survey of a 0.5 deg x 0.5 deg area of the Galactic Plane using the WFI instrument on the 2.2-m ESO telescope on La Silla, Chile. The dataset comprises a total of 267 R-band images, 204 from a 16 day observation run in 2005, supplemented by 63 images from a six week period in 2002. Our reduction employed the new numerical kernel difference image analysis method as implemented in the PYSIS3 code and resulted in more than 500,000 lightcurves of stars down to a magnitude limit of R ~ 24.5. A search for variable stars resulted in the detection of 1318 variables of different types. 1011 of these are eclipsing or contact binary stars. A number of the contact binaries have low mass-ratios and several of the detached binaries appear to have low-mass components. Three candidate contact binaries have periods at the known cut off including two with periods lower than any previously published. Also identified are 3 possible pre-main sequence detached eclipsing binaries.Comment: 54 pages, 17 figures, 11 tables, accepted by A&A. Photometry will be available through CD

The Optical Afterglow of GRB 011211

We present early-time optical photometry and spectroscopy of the optical afterglow of the gamma-ray burst GRB 011211. The spectrum of the optical afterglow contains several narrow metal lines which are consistent with the burst occurring at a redshift of 2.140 +/- 0.001. The optical afterglow decays as a power law with a slope of alpha = 0.83 +/- 0.04 for the first approximately two days after the burst at which time there is evidence for a break. The slope after the break is at least 1.4. There is evidence for rapid variations in the R-band light approximately 0.5 days after the burst. These variations suggest that there are density fluctuations near the gamma-ray burst on spatial scales of approximately 40--125 AU. The magnitude of the break in the light curve, the spectral slope, and the rate of decay in the optical, suggest that the burst expanded into an ambient medium that is homogeneous on large scales. We estimate that the local particle density is between approximately 0.1 and 10 cm^{-3} and that the total gamma-ray energy in the burst was 1.2--1.9 x 10^{50} erg. This energy is smaller than, but consistent with, the ``standard'' value of (5 +/- 2) x 10^{50} erg. Comparing the observed color of the optical afterglow with predictions of the standard beaming model suggests that the rest-frame V-band extinction in the host galaxy is less than approximately 0.03 mag.Comment: 17 pages, 4 figures, AASTeX 5.02, to appear in AJ Referee's report incorporated, minor changes in the tex

The Cepheid Phase Lag Revisited

We compute the phase lags between the radial velocity curves and the light curves $\Delta \Phi_1= \phi^{V_r}_1 - \phi^{mag}_1$ for classical Cepheid model sequences both in the linear and the nonlinear regimes. The nonlinear phase lags generally fall below the linear ones except for high period models where they lie above, and of course for low pulsation amplitudes where the two merge. The calculated phase lags show good agreement with the available observational data of normal amplitude Galactic Cepheids. The metallicity has but a moderate effect on the phase lag, while the mass-luminosity relation and the parameters of the turbulent convective model (time-dependent mixing length) mainly influence the modal selection and the period, which is then reflected in the period -- $\Delta \Phi_1$ diagram. We discuss the potential application of this observable as a discriminant for pulsation modes and as a test for ultra-low amplitudes (ULA) pulsation.Comment: 11 pages, 8 figures, accepted for publication in ApJ, minor revisions in the text and figures, (black and white version available from 2nd author's website

Central Action of Botulinum Toxin Type A – is it Possible?

Botulinum toxin (BoTx) is a product of gram-positive anaerobic bacteria of the Clostridium genus. At present, seven serotypes (A to G) of BoTx have been identified. Each of them functions as a zinc-dependent endopeptidase that hydrolyzes peptide bonds within soluble N-ethylmaleimide-sensitive factor attaching protein receptors. BoTx affects proteins required for neurotransmitter release through presynaptic membranes. As a result, muscle weakness develops, or complete paralysis of the muscles occurs. These effects are not only limited to striated muscles but also may have impact on smooth muscles and secretory glands. The observation that BoTx can diffuse from the site of administration may indicate the possibility of direct or indirect influence of the toxin on the CNS. Consequently, the question arises: What is the mechanism of the central action of BoTx? Several mechanisms of such action have been proposed. However, recent findings showed that the most probable mechanism responsible for the central effects of BoTx action is its anterograde transport. In this review, we describe and discuss the most important aspects related to BoTx action on the CNS.Ботуліновий токсин (BoTx) є продуктом життєдіяльності грампозитивних бактерій роду Clostridium. На теперішній час ідентифіковано сім серотипів BoTx (A–G). Всі вони функціонують як цинкзалежні ендопеотидази, що гідролізують пептидні зв’язки з розчинним N-етилмалеімідчутливим фактором, контактуючим з протеїновими рецепторами. BoTx впливає на протеїни, необхідні для вивільнення нейротрансмітерів через пресинаптичні мембрани. Як результат, розвиваються м’язова слабкість або повний параліч м’язів. Такі ефекти не обмежуються поперечносмугастими м’язами, вони виявляються також у гладеньких м’язах та секреторних залозах. Як спостерігалося, BoTx може дифундувати від місця свого введення; це може вказувати на принципову можливість прямих або непрямих впливів токсину на ЦНС. Відповідно, виникає питання: яким є механізм центральної дії BoTx. Було запропоновано декілька гіпотез про механізми такої дії. Результати нещодавніх досліджень, однак, свідчать про те, що найбільш вірогідним механізмом, відповідальним за центральні ефекти BoTx, є його дія на антероградний транспорт. У нашому огляді ми описуємо та обговорюємо найбільш важливі аспекти дії BoTx на ЦНС