Water management subsystem specification for space flights of extended time periods. Life support system for space flights of extended time periods
Water management subsystem of life support system for manned space flight specifications
WATER↗
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Ionosphere observations during the period of solar eclipse of 15 february 1961 ionosfernyye nablyudeniya v period solnechnogo zatmeniya 15 fevralya 1961 g.
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Kulikov, N. N.↗
An experimental and theoretical investigation of turbulence instabilities at plasma magnetic field interfaces Semiannual report for period ending Apr. 1967 and final report for period ending Jan. 1968
Turbulence instabilities at plasma magnetic field interfaces, and plasma vortices in coaxial plasma accelerator
Bostick, W. H.↗
Short-period and long-period perturbations of a spherical satellite due to direct solar radiation
On the basis of expressions derived by Kozai (1961) and those developed in this paper, a detailed semianalytic algorithm is presented for calculating radiation-pressure perturbations in the Keplerian elements. Through some simple modifications, the algorithm is also made to hold when e = 0, i = 0, or both. The perturbations are obtained by summing over the sunlit segment of the satellite's orbit during each revolution or part thereof. The end points of this segment are evaluated numerically once per revolution. The effect of the inherent uncertainties in the boundaries of the earth's shadow is discussed. The algorithm is tested by means of numerical integration of the equations of motion and through comparisons with observations of the balloon satellite 1963 30D during a 200-day interval.
Aksnes, K.↗
Performance Comparison of a Set of Periodic and Non-Periodic Tridiagonal Solvers on SP2 and Paragon Parallel Computers
Various tridiagonal solvers have been proposed in recent years for different parallel platforms. In this paper, the performance of three tridiagonal solvers, namely, the parallel partition LU algorithm, the parallel diagonal dominant algorithm, and the reduced diagonal dominant algorithm, is studied. These algorithms are designed for distributed-memory machines and are tested on an Intel Paragon and an IBM SP2 machines. Measured results are reported in terms of execution time and speedup. Analytical study are conducted for different communication topologies and for different tridiagonal systems. The measured results match the analytical results closely. In addition to address implementation issues, performance considerations such as problem sizes and models of speedup are also discussed.
Sun, Xian-He↗
Increase in nitrate uptake by soybean plants during interruption of the dark period with low intensity light
Diurnal patterns of net NO3- uptake by nonnodulated soybean [Glycine max (L.) Merr. cv. Ransom] plants growing in flowing hydroponic culture at 26 and 16 degrees C root temperatures were measured at hourly intervals during alternate days of a 12-day growth period. Ion chromatography was used to determine removal of NO3- from the culture solution. Day and night periods of 9 and 15 h were used during growth. The night period included two 6-h dark periods and an intervening 3-h period of night interruption by incandescent lamps to effect a long-day photoperiod and repress floral initiation. At both root temperatures, the average specific rates of NO3- uptake were twice as great during the night interruption period as during the day period; they were greater during the day period than during the dark periods; and they were greater during the dark period immediately following the day period than during the later dark period that followed the night interruption. While these average patterns were repetitious among days, measured rates of uptake varied hourly and included intervals of net efflux scattered through the day period and more frequently through the 2 dark periods. Root temperature did not affect the average daily specific rates of uptake or the qualitative relationships among day, dark and night interruption periods of the diurnal cycle.
Non-NASA Center↗
Phenology Shifts at Start vs. End of Growing Season in Temperate Vegetation Over the Northern Hemisphere for the Period 1982-2008
Changes in vegetative growing seasons are dominant indicators of the dynamic response of ecosystems to climate change. Therefore, knowledge of growing seasons over the past decades is essential to predict ecosystem changes. In this study, the long-term changes in the growing seasons of temperate vegetation over the Northern Hemisphere were examined by analyzing satellite-measured normalized difference vegetation index and reanalysis temperature during 1982 2008. Results showed that the length of the growing season (LOS) increased over the analysis period; however, the role of changes at the start of the growing season (SOS) and at the end of the growing season (EOS) differed depending on the time period. On a hemispheric scale, SOS advanced by 5.2 days in the early period (1982-1999) but advanced by only 0.2 days in the later period (2000-2008). EOS was delayed by 4.3 days in the early period, and it was further delayed by another 2.3 days in the later period. The difference between SOS and EOS in the later period was due to less warming during the preseason (January-April) before SOS compared with the magnitude of warming in the preseason (June September) before EOS. At a regional scale, delayed EOS in later periods was shown. In North America, EOS was delayed by 8.1 days in the early period and delayed by another 1.3 days in the later period. In Europe, the delayed EOS by 8.2 days was more significant than the advanced SOS by 3.2 days in the later period. However, in East Asia, the overall increase in LOS during the early period was weakened in the later period. Admitting regional heterogeneity, changes in hemispheric features suggest that the longer-lasting vegetation growth in recent decades can be attributed to extended leaf senescence in autumn rather than earlier spring leaf-out. Keywords: climate change, growing season, NDVI (normalized difference vegetation index), Northern Hemisphere, phenology,
Jeong, Su-Jong↗
Coincident 1.3-year Periodicities in the ap Geomagnetic Index and the Solar Wind
Recent observations show an approximately 1.3-year period in the speed of the solar wind detected by the IMP 8 and Voyager 2 spacecraft. A similar period is also seen in the north-south (GSE) component of the magnetic field observed by IMP 8. Since both parameters are commonly used as input to models of geomagnetic activity, the 'ap' index (a measure of geomagnetic disturbance) is examined to look for this periodicity. The Lomb-Scargle periodogram method is used on the ap, plasma, and magnetic field data during the 1973-1994 time range. A dynamic FFT periodogram method is also used to analyze the ap data during this time, as well as to look for periods present between 1932 and 1972. A clear 1.3-year periodicity is present in the post-1986 data when the same period is observed in the plasma and field data. The V(2)B(zsm) and V(2)B(s) proxies for geomagnetic activity also show this periodicity. However, the southward (GSM) component of the magnetic field does not have a 1.3-year period, and neither do solar wind or ap data from 1973-1985. This demonstrates that the ap geomagnetic index can act as a proxy for solar wind periodicities at this time scale. Historic ap data are examined, and show that a similar periodicity in ap exists around 1942. Since auroral data show a 1.4-year periodicity, all these similar periods may result from a common underlying solar mechanism.
Paularena, K. I.↗
Burst Oscillation Periods from 4U 1636-53: A Constraint on the Binary Doppler Modulation
The burst oscillations seen during Type 1 X-ray bursts from low mass X-ray binaries (LMXB) typically evolve in period towards an asymptotic limit that likely reflects the spin of the underlying neutron star. If the underlying period is stable enough, measurement of it at different orbital phases may allow a detection of the Doppler modulation caused by the motion of the neutron star with respect to the center of mass of the binary system. Testing this hypothesis requires enough X-ray bursts and an accurate optical ephemeris to determine the binary phases at which they occurred. We present here a study of the distribution of asymptotic burst oscillation periods for a sample of 26 bursts from 4U 1636-53 observed with the Rossi X-ray Timing Explorer (RXTE). The burst sample includes both archival and proprietary data and spans more than 4.5 years. We also present new optical light curves of V801 Arae, the optical counterpart of 4U 1636-53, obtained during 1998-2001. We use these optical data to refine the binary period measured by Augusteijn et al. to 3.7931206(152) hours. We show that a subset of approx. 70% of the bursts form a tightly clustered distribution of asymptotic periods consistent with a period stability of approx. 1 x 10(exp -4). The tightness of this distribution, made up of bursts spanning more than 4 years in time, suggests that the underlying period is highly stable, with a time to change the period of approx. 3 x 10(exp 4) yr. This is comparable to similar numbers derived for X-ray pulsars. We investigate the period and orbital phase data for our burst sample and show that it is consistent with binary motion of the neutron star with v(sub ns) sin i < 38 and 50 km/s at 90 and 99% confidence, respectively. We use this limit as well as previous radial velocity data to constrain the binary geometry and component masses in 4U 1636-53. Our results suggest that unless the neutron star is significantly more massive than 1.4 solar masses the secondary is unlikely to have a mass as large as 0.36 solar masses, the mass estimated assuming it is a main sequence star which fills its Roche lobe. We show that a factor of 3 increase in the number of bursts with asymptotic period measurements should allow a detection of the neutron star velocity.
Giles, A. B.↗
Solar Rotational Periodicities and the Semiannual Variation in the Solar Wind, Radiation Belt, and Aurora
The behavior of a number of solar wind, radiation belt, auroral and geomagnetic parameters is examined during the recent extended solar minimum and previous solar cycles, covering the period from January 1972 to July 2010. This period includes most of the solar minimum between Cycles 23 and 24, which was more extended than recent solar minima, with historically low values of most of these parameters in 2009. Solar rotational periodicities from S to 27 days were found from daily averages over 81 days for the parameters. There were very strong 9-day periodicities in many variables in 2005 -2008, triggered by recurring corotating high-speed streams (HSS). All rotational amplitudes were relatively large in the descending and early minimum phases of the solar cycle, when HSS are the predominant solar wind structures. There were minima in the amplitudes of all solar rotational periodicities near the end of each solar minimum, as well as at the start of the reversal of the solar magnetic field polarity at solar maximum (approx.1980, approx.1990, and approx. 2001) when the occurrence frequency of HSS is relatively low. Semiannual equinoctial periodicities, which were relatively strong in the 1995-1997 solar minimum, were found to be primarily the result of the changing amplitudes of the 13.5- and 27-day periodicities, where 13.5-day amplitudes were better correlated with heliospheric daily observations and 27-day amplitudes correlated better with Earth-based daily observations. The equinoctial rotational amplitudes of the Earth-based parameters were probably enhanced by a combination of the Russell-McPherron effect and a reduction in the solar wind-magnetosphere coupling efficiency during solstices. The rotational amplitudes were cross-correlated with each other, where the 27 -day amplitudes showed some of the weakest cross-correlations. The rotational amplitudes of the > 2 MeV radiation belt electron number fluxes were progressively weaker from 27- to 5-day periods, showing that processes in the magnetosphere act as a low-pass filter between the solar wind and the radiation belt. The A(sub p)/K(sub p) magnetic currents observed at subauroral latitudes are sensitive to proton auroral precipitation, especially for 9-day and shorter periods, while the A(sub p)/K(sub p) currents are governed by electron auroral precipitation for 13.5- and 27-day periodicities.
Emery, Barbara A.↗
Short-period circumnutations found in sunflower hypocotyls in satellite orbit. A reappraisal of data from Spacelab-1
We have further analysed data from an experiment performed in satellite orbit, in Spacelab-1. In micro-gravity the hypocotyls of Helianthus annuus, cv. "Teddy Bear", showed short period circumnutations (periods around 30 minutes) as well as the already reported long period nutations (with an average period of about 115 minutes). We applied various types of signal analysis (Fourier and wavelet analysis) to the data series. The long period circumnutations have a larger amplitude than the short term circumnutations. Both short and long period circumnutations exist in one and the same hypocotyl. (This is in contrast to our ground control experiments, where were found only the long-period nutations.) The period of the nutations changed throughout the experiment. These results are extending the conclusions drawn after the Spacelab experiment (Brown et al. 1990). In particular they emphasize the existence of both short- and long-period circumnutations in micro-gravity.
short duration↗
Mass transfer in cataclysmic variables - Clues from the dwarf nova period distribution
Evidence is presented in support of the hypothesis that the mean mass-transfer rate at a given orbital period is not continuous across the 2-3 hr gap in the orbital period distribution for cataclysmic variables. It is pointed out that although dwarf novae comprise nearly half (48 percent) of all disk systems with orbital periods less than 10 hr, only three systems out of the 22 with periods between 3 and 4 hr appear to be dwarf novae. The overall orbital period distribution for dwarf novae in conjunction with the predictions from current theories of dwarf nova eruptions are used to argue that mass-transfer rates must be generally higher for systems with orbital periods greater than 3 hr relative to systems with periods less than 2 hr. It is further argued that the mean mass-transfer rate at a given orbital period cannot increase more steeply than P exp 1.7 unless the white dwarf mass is positively correlated with orbital period.
Shafter, A. W.↗
The 77 day periodicity in the flare rate of cycle 22
The ocurrence times of major flares of solar cycle 22 are analyzed to detect periodicities. It is found that a periodicity of 77 d was in operation in the 15-m interval from 1988 November to 1990 February for six cycles. During the rest of 1990 no periodicity was discernible; however, it seems that the 77-d periodicity resumed in 1991. This 77-d period is interpreted as the third subharmonic of the fundamental period of about 25.5 d. In this interpretation, the 154-d periodicity is the sixth subharmonic. It is also found that when the 77-d periodicity or the 154-d periodicity is in operation the occurrence rate of major flares is much higher than is expected form the relative sunspot number.
Bai, T.↗
AH Cam: A metal-rich RR Lyrae star with the shortest known Blazhko period
Analysis of 746 new V-band observations of the RR Lyrae star AH Cam obtained during 1989 - 1992 clearly show that its light curve cannot be described by a single period. In fact, at first glance, the Fourier spectrum of the photometry resembles that of a double-mode pulsator, with peaks at a fundamental period of 0.3686 d and an apparent secondary period of 0.2628 d. Nevertheless, the dual-mode solution is a poor fit to the data. Rather, we believe that AH Cam is a single-mode RR Lyrae star undergoing the Blazhko effect: periodic modulation of the amplitude and shape of its light curve. What was originally taken to be the period of the second mode is instead the 1-cycle/d alias of a modulation sidelobe in the Fourier spectrum. The data are well described by a modulation period of just under 11 d, which is the shortest Blazhko period reported to date in the literature and confirms the earlier suggestion by Goranskii. A low-resolution spectrum of AH Cam indicates that it is relatively metal rich, with delta-S less than or = 2. Its high metallicity and short modulation period may provide a critical test of at least one theory for the Blazhko effect. Moskalik's internal resonance model makes specific predictions of the growth rate of the fundamental model vs fundamental period. AH Cam falls outside the regime of other known Blazhko variables and resonance model predictions, but these are appropriate for metal-poor RR Lyrae stars. If the theory matches the behavior of AH Cam for a metal-rich stellar model, this would bolster the resonance hypothesis.
Smith, Horace A.↗
NADH oxidase activity (NOX) and enlargement of HeLa cells oscillate with two different temperature-compensated period lengths of 22 and 24 minutes corresponding to different NOX forms
NOX proteins are cell surface-associated and growth-related hydroquinone (NADH) oxidases with protein disulfide-thiol interchange activity. A defining characteristic of NOX proteins is that the two enzymatic activities alternate to generate a regular period length of about 24 min. HeLa cells exhibit at least two forms of NOX. One is tumor-associated (tNOX) and is inhibited by putative quinone site inhibitors (e.g., capsaicin or the antitumor sulfonylurea, LY181984). Another is constitutive (CNOX) and refractory to inhibition. The periodic alternation of activities and drug sensitivity of the NADH oxidase activity observed with intact HeLa cells was retained in isolated plasma membranes and with the solubilized and partially purified enzyme. At least two activities were present. One had a period length of 24 min and the other had a period length of 22 min. The lengths of both the 22 and the 24 min periods were temperature compensated (approximately the same when measured at 17, 27 or 37 degrees C) whereas the rate of NADH oxidation approximately doubled with each 10 degrees C rise in temperature. The rate of increase in cell area of HeLa cells when measured by video-enhanced light microscopy also exhibited a complex period of oscillations reflective of both 22 and 24 min period lengths. The findings demonstrate the presence of a novel oscillating NOX activity at the surface of cancer cells with a period length of 22 min in addition to the constitutive NOX of non-cancer cells and tissues with a period length of 24 min.
Non-NASA Center↗
Secondary periodicities of microbursts of TeV gamma rays from the Crab pulsar
Observations were made during the past several years on the Crab pulsar using the Ooty atmospheric Cerenkov array with the aim of detecting possible emission of ultra high energy gamma rays by the pulsar. During the course of these observations, it was found that the Crab pulsar emits TeV gamma rays in bursts of short duration. The microbursts of TeV gamma rays from the Crab pulsar, which were seen in the data of at least three years, also reveal interesting secondary periodicities. It was noticed at first that some bursts could be connected with the others that occurred during the same night or during the next two nights with integral number of cycles of periods 43 + or - 1 minute. Ten possible periods in the vicinity of 43 minutes were determined for all the combinations of bursts for each year. The best values of periods thus obtained were different from year to year. But when, instead of the real time, the number of Crab cycles elapsed between the bursts was used as the unit of time, two values of burst periods - 77460 and 77770 Crab cycles - were found to be significant in the data of at least two years. A Monte Carlo simulation using 1500 trial periods chosen randomly within + or - 5 minutes of the original burst period did not reveal any value of the period as significant.
Vishwanath, P. R.↗
Light variations of Periodic Comet Halley beyond 7 AU
The present examination of brightness data on the Periodic Comet Halley over the October 1982-February 1984 period, for evidence concerning nucleus rotation period and projected cross section area, notes variations of up to 5:1 in intrinsic brightness. Application of a period-determination technique has failed to yield a clear choice for the true rotation period among a large number of peaks in the spectrum, some of which virtually coincide with the sun's rotation period and its submultiples. It is found that rotation periods longer than about 1 day are the most likely; it is suggested that the observed light curve is a composition of periodic and erratic variations.
Sekanina, Z.↗
A search for five month solar induced periodicity in the stratosphere
Recent studies of solar UV spectra and various indices of solar activity indicate a strong period at about 5 months. In the 10.7 cm solar radio flux (F10.7), a conventional index for the solar EUV and UV variabilities, the spectral power of the 5 month period is comparable to the well known 27 day solar period. However, in the solar UV flux at 205 nm, directly measured from the Nimbus-7 SBUV spectrometer, the (spectral) power of the 5 month period is about half that of the 27 day period. This paper examines the possible impact of the 5 month solar period on ozone and temperature at various pressure levels in the stratosphere and discusses the implications of differences in solar forcing at the 27 day and 5 month periods. It is shown that ozone, both in the lower and the upper stratosphere, has a measurable response to solar UV forcing at 27 days. Such a solar response is not observed at 5 month period because of a relatively weaker 5 month solar UV component in the solar signal and a strong interference from dynamical signals associated with planetary wave activity.
Chandra, S.↗