Spectator detection for the measurement of proton neutron interactions at ANKE

A telescope of three silicon detectors has been installed close to the internal target position of the ANKE spectrometer, which is situated inside the ultra-high vacuum of the COSY-Juelich light-ion storage ring. The detection and identification of slow protons and deuterons emerging from a deuterium cluster-jet target thus becomes feasible. A good measurement of the energy and angle of such a spectator proton (p_sp) allows one to identify a reaction as having taken place on the neutron in the target and then to determine the kinematical variables of the ion-neutron system on an event-by-event basis over a range of c.m. energies. The system has been successfully tested under laboratory conditions. By measuring the spectator proton in the p d to p_sp d pi^0 reaction in coincidence with a fast deuteron in the ANKE Forward Detector, values of the p n to d pi^0 total cross-section have been deduced. Further applications of the telescope include the determination of the luminosity and beam polarisation which are required for several experiments.Comment: 16 pages, 9 figure

First results of meteor radar lower thermosphere wind measurements at Dixon, Arctic (73.5゜N, 80゜E)

Results of simultaneous wind measurements by the identical meteor radars at Dixon (73.5°N, 80°E) and Obninsk (55°N, 37°E) are presented for the time interval from November 12, 1999 to July 31, 2000. A number of features were observed which require comprehensive investigation on the basis of long-term wind measurements in the high-latitude lower thermosphere. The observed semidiurnal tide phases at Dixon are close to those published for Troms0, providing some evidence for predominance of the migrating semidiurnal tide for semidiurnal oscillations at this latitude. Highly coherent oscillations in tidal amplitudes and prevailing winds were also revealed, as well as time intervals with non-significant semidiurnal tide during which oscillations with periods different from but close to 12 h were observed

The summertime 12-h wind oscillation with zonal wavenumber <i>s</i> = 1 in the lower thermosphere over the South Pole

International audienceMeteor radar measurements of winds near 95 km in four azimuth directions from the geographic South Pole are analyzed to reveal characteristics of the 12-h oscillation with zonal wavenumber one (s=1). The wind measurements are confined to the periods from 19 January 1995 through 26 January 1996 and from 21 November 1996 through 27 January 1997. The 12-h s=1 oscillation is found to be a predominantly summertime phenomenon, and is replaced in winter by a spectrum of oscillations with periods between 6 and 11.5 h. Both summers are characterized by minimum amplitudes (5?10 ms?1) during early January and maxima (15?20 ms?1) in November and late January. For 10-day means of the 12-h oscillation, smooth evolutions of phase of order 4?6 h occur during the course of the summer. In addition, there is considerable day-to-day variability (±5?10 ms?1 in amplitude) with distinct periods (i.e., ~5 days and ~8 days) which suggests modulation by planetary-scale disturbances. A comparison of climatological data from Scott Base, Molodezhnaya, and Mawson stations suggests that the 12-h oscillation near 78°S is s=1, but that at 68°S there is probably a mixture between s=1 and other zonal wavenumber oscillations (most probably s=2). The mechanism responsible for the existence of the 12-h s=1 oscillation has not yet been identified. Possible origins discussed herein include in situ excitation, nonlinear interaction between the migrating semidiurnal tide and a stationary s=1 feature, and thermal excitation in the troposphere

Climatological lower thermosphere winds as seen by ground-based and space-based instruments

Comparisons are made between climatological dynamic fields obtained from ground-based (GB) and space-based (SB) instruments with a view towards identifying SB/GB intercalibration issues for TIMED and other future aeronomy satellite missions. SB measurements are made from the High Resolution Doppler Imager (HRDI) instrument on the Upper Atmosphere Research Satellite (UARS). The GB data originate from meteor radars at Obninsk, (55° N, 37° E), Shigaraki (35° N, 136° E) and Jakarta (6° S, 107° E) and MF spaced-antenna radars at Hawaii (22° N, 160° W), Christmas I. (2° N, 158° W) and Adelaide (35° S, 138° E). We focus on monthly-mean prevailing, diurnal and semidiurnal wind components at 96km, averaged over the 1991-1999 period. We perform space-based (SB) analyses for 90° longitude sectors including the GB sites, as well as for the zonal mean. Taking the monthly prevailing zonal winds from these stations as a whole, on average, SB zonal winds exceed GB determinations by ~63%, whereas meridional winds are in much better agreement. The origin of this discrepancy remains unknown, and should receive high priority in initial GB/SB comparisons during the TIMED mission. We perform detailed comparisons between monthly climatologies from Jakarta and the geographically conjugate sites of Shigaraki and Adelaide, including some analyses of interannual variations. SB prevailing, diurnal and semidiurnal tides exceed those measured over Jakarta by factors, on the average, of the order of 2.0, 1.6, 1.3, respectively, for the eastward wind, although much variability exists. For the meridional component, SB/GB ratios for the diurnal and semidiurnal tide are about 1.6 and 1.7. Prevailing and tidal amplitudes at Adelaide are significantly lower than SB values, whereas similar net differences do not occur at the conjugate Northern Hemisphere location of Shigaraki. Adelaide diurnal phases lag SB phases by several hours, but excellent agreement between the two data sources exists for semidiurnal tidal phases throughout the year. These results are consistent with phase retardation effects in the MF radar technique that are thought to exist above about 90km. Prevailing and tidal amplitudes from Shigaraki track year-to-year variations in SB fields, whereas in the Southern Hemisphere poorer agreement exists. The above hemispheric differences are due in part to MF vs. meteor radar techniques, but zonal asymmetries and day-to-day variability, combined with inadequate sampling, may also be playing a role. Based on these results, some obvious recommendations emerge that are relevant to combined GB/SB studies as part of TIMED and other future aeronomy missions.J. M. Forbes, Yu. I. Portnyagin, W. Skinner, R. A. Vincent, T. Solovjova, E. Merzlyakov, T. Nakamura, and S. Pal

High- and mid-latitude quasi-2-day waves observed simultaneouslyby four meteor radars during summer 2000

International audienceResults from the analysis of MLT wind measurements at Dixon (73.5°N, 80°E), Esrange (68°N, 21°E), Castle Eaton (UK) (53°N, 2°W), and Obninsk (55°N, 37°E) during summer 2000 are presented in this paper. Using S-transform or wavelet analysis, quasi-two-day waves (QTDWs) are shown to appear simultaneously at high- and mid-latitudes and reveal themselves as several bursts of wave activity. At first this activity is preceded by a 51?53h wave with S=3 observed mainly at mid-latitudes. After a short recess (or quiet time interval for about 10 days near day 205), we observe a regular sequence of three bursts, the strongest of them corresponding to a QTDW with a period of 47?48h and S=4 at mid-altitudes. We hypothesize that these three bursts may be the result of constructive and destructive interference between several spectral components: a 47?48h component with S=4; a 60-h component with S=3; and a 80-h component with S=2. The magnitudes of the lower (higher) zonal wave-number components increase (decrease) with increasing latitude. The S-transform or wavelet analysis indicates when these spectral components create the wave activity bursts and gives a range of zonal wave numbers for observed bursts from about 4 to about 2 for mid- and high-latitudes. The main spectral component at Dixon and Esrange latitudes is the 60-h oscillation with S=3. The zonal wave numbers and frequencies of the observed spectral components hint at the possible occurrence of the nonlinear interaction between the primary QTDWs and other planetary waves. Using a simple 3-D nonlinear numerical model, we attempt to simulate some of the observed features and to explain them as a consequence of the nonlinear interaction between the primary 47?48h and the 9?10day waves, and the resulting linear superposition of primary and secondary waves. In addition to the QTDW bursts, we also infer forcing of the 4-day wave with S=2 and the 6?7day wave with S=1, possibly arising from nonlinear decoupling of the 60-h wave with S=3. The starting mechanism for this decoupling is the Rossby wave instability (e.g. Baines, 1976). This result is consistent with the day-to-day wind variability during the observed QTDW events. An interesting feature of the final stage of the observed QTDW activity in summer 2000 is the occurrence of strong 4?5 day waves with S=3. Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides; general or miscellaneous

Оценка антиоксидантной активности экстрактов из морских водорослей Японского моря in vitro и in vivo

Морские водоросли являются источником важных биологически активных соединений — липидов, аминокислот, фенолов, полисахаридов и др. Перспективную группу веществ морского происхождения составляют полифенольные соединения, обладающие высокой антиоксидантной активностью, которые играют ключевую роль в жизнедеятельности морских макрофитов, что позволяет им быстро реагировать на внешний стресс и выполнять защитные функции. В то же время многокомпонентный состав фенольной фракции экстракта из водорослей обусловливает широкий спектр её фармакологической активности, включающей регулирующее влияние на многочисленные нарушения гомеостаза при патологических процессах в организме животных и человека. При этом имеющиеся возможности практического использования экстрактов из водорослей ещё не исчерпаны, что представляет несомненный интерес для современной науки. Цель работы — выполнить сравнительную оценку антиоксидантной активности водно-спиртовых экстрактов, выделенных из талломов представителей трёх классов водорослей [бурых (Sargassum pallidum), зелёных (Ulva lactuca) и красных (Ahnfeltia fastigiata var. tobuchiensis)], а также проанализировать их влияние на показатели антиоксидантной защиты печени и плазмы крови мышей при экспериментальном стрессе. Водоросли собирали в летние месяцы в прибрежных водах залива Петра Великого Японского моря, затем сушили при температуре около +50 °C, измельчали на лабораторной мельнице до частиц размером 0,5–1 мм и экстрагировали 70%-ным этиловым спиртом методом реперколяции. Наибольшее количество полифенолов отмечено в экстракте бурой водоросли S. pallidum — (218,2 ± 20,3) мг-экв ГК·г−1 сухого веса. В экстракте зелёной водоросли U. lactuca значение этого показателя составляло (16,2 ± 1,8) мг-экв ГК·г−1 сухого веса, в экстракте красной водоросли A. fastigiata var. tobuchiensis — (9,1 ± 1,6) мг-экв ГК·г−1 сухого веса. Соответственно, антирадикальная активность экстракта S. pallidum по отношению к катион-радикалу 2,2’-азино-бис(3-этилбензотиазолин-6-сульфоновой кислоты) (ABTS+) и алкилпероксильному радикалу была существенно выше, чем таковая экстрактов U. lactuca и A. fastigiata var. tobuchiensis. Проведена экспериментальная проверка с целью определить влияние исследуемых экстрактов водорослей на показатели антиоксидантной защиты печени и плазмы мышей в условиях острого стресса. В задачи эксперимента входило установление весовых показателей (вес животных, индекс массы внутренних органов) и биохимических параметров (уровень антирадикальной активности, содержание малонового диальдегида и восстановленного глутатиона, активность антиоксидантных ферментов). Эксперимент по стрессовому воздействию проводили на белых беспородных мышах-самцах массой 20–30 г. Острый стресс моделировали путём вертикальной фиксации животных за дорсальную шейную складку на 24 ч. Освобождённые от спирта экстракты водорослей вводили в виде водной взвеси в дозе 100 мг общих полифенолов на кг массы тела в желудок мышам через зонд дважды — непосредственно перед вертикальной фиксацией и спустя 6 ч. Животным контрольной группы и группы «стресс» вводили дистиллированную воду в объёме, равном объёму вводимых препаратов. В данной модели проявились все атрибуты стресса: гипертрофия надпочечников, инволюция тимуса и селезёнки, изъязвления слизистой желудка и кишечника. Также были отмечены нарушения системы антиоксидантной защиты, которые выражались в снижении активности антиоксидантных ферментов в плазме крови, уменьшении содержания восстановленного глутатиона в печени и увеличении уровня малонового диальдегида. Под действием экстрактов во всех группах животных на фоне стресса прослежена тенденция к стабилизации исследуемых показателей антиоксидантной защиты. При этом показатели у мышей, получавших экстракты из U. lactuca и A. fastigiata var. tobuchiensis, уступали аналогичным параметрам в группе животных, получавших экстракт S. pallidum. В группе животных, получавших экстракт S. pallidum, в показателях антиоксидантной защиты не было выявлено достоверных отличий от контрольных значений. Данный факт обусловлен тем, что основными компонентами полифенольных фракций зелёных и красных водорослей являются мономерные флавоноиды, тогда как в бурых водорослях присутствуют высокомолекулярные флоротаннины, которые проявляют более высокую антиоксидантную активность, чем низкомолекулярные полифенольные фракции зелёных и красных водорослей