The GOLF experiment on the SOHO mission aims to study the internal structure of the Sun by measuring the spectrum of global oscillations in the frequency range 10 super(-) super(7) to 10 super(-) ...super(2) Hz. Here we present the results of the analysis of the first 8 months of data. Special emphasis is put into the frequency determination of the p modes, as well as the splitting in the multiplets due to rotation. For both, we show that the improvement in S/N level with respect to the ground-based networks and other experiments is essential in achieving a very low-degree frequency table with small errors ( similar to 2 parts in 10 super(5) ). On the other hand, the splitting found seems to favour a solar core which does not rotate slower than its surface. The line widths do agree with theoretical expectations and other observations.
This article presents a comparative analysis of solar activity data, Mt Wilson diameter data, Super-Kamiokande solar neutrino data, and nuclear decay data acquired at the Lomonosov Moscow State ...University (LMSU). We propose that salient periodicities in all of these datasets may be attributed to r-mode oscillations. Periodicities in the solar activity data and in Super-Kamiokande solar neutrino data may be attributed to r-mode oscillations in the known tachocline, with normalized radius in the range 0.66a0.74, where the sidereal rotation rate is in the range 13.7a14.6 year-1. We propose that periodicities in the Mt Wilson and LMSU data may be attributed to similar r-mode oscillations where the sidereal rotation rate is approximately 12.0 year-1, which we attribute to a hypothetical ainnera tachocline separating a slowly rotating core from the radiative zone. We also discuss the possible role of the Resonant Spin Flavor Precession (RSFP) process, which leads to estimates of the neutrino magnetic moment and of the magnetic field strength in or near the solar core.
We have used the daily values of the equatorial rotation rate determined from the Mt.Wilson daily Doppler-velocity measurements during the period 3 December 1985-5March 2007 to search for ...periodicities in the solar equatorial rotation rate on time scales shorter than 11 years. After the daily values have been binned into 61-day intervals, a cosine fit with a period of one year was applied to the sequence to remove any seasonal trend. The spectral properties of this sequence were then investigated by using standard Fourier analysis, maximum-entropy methods, and a Morlet-wavelet analysis. From the analysis of the Fourier power spectrum we detected peaks with periodicities around 7.6, 2.8, and 1.47years and 245, 182, and 158days, but none of them were at a statistically significant level. In the Morlet-wavelet analysis the -1.47-year periodicity is detected only for 1990 (i.e., near the maximum of cycle22) and near the end of cycle22 in 1995. From the same wavelet analysis we found some evidence for the existence of a 2.8-year periodicity and a 245-day periodicity in the equatorial rotation rate around the years 1990 and 1992, respectively. In the data taken during the period 1996-2007, when the Mt.Wilson spectrograph instrumentation was more stable, we were unable to detect any signal from the wavelet analysis. Thus, the detected periodicities during the period before 1996 could be artifacts of frequent changes in the Mt.Wilson spectrograph instrumentation. However, the temporal behavior of most of the activity phenomena during cycles 22 (1986-1996) and 23 (after 1997) is considerably different. Therefore, the presence of the aforementioned short-term periodicities during the last cycle and absence of them in the current cycle may, in principle, be real temporal behavior of the solar rotation during these cycles.
Chemoenzymatic synthesis of 1- O-hexadecyl-2- O-palmitoyl- sn-glycerol was achieved by esterification of 1- O-hexa-decyl-sn-glycerol, with palmitic acid in the presence of ...N,N-dicyclohexylcarbodiimide, and then subjected to alco-holysis catalysed by an immobilized 1,3-specific lipase. The highest yield (90% from 0.3 mM) was obtained in 3 h, using methyl isobutyl ketone as solvent with water activity 0.2.PUBLICATION ABSTRACT
Amastigote forms of
T. cruzi express the specific Ssp-4 surface antigen which is progressively shed, by the action of an endogenous phosphatidylinositol-phospholipase C, during their development into ...epimastigotes (Andrews et al., J. Exp. Med., 167 (1988) 300–314). We show now that the lipid moiety of the anchor of Ssp-4 is a ceramide which was metabolically labelled with
3Hpalmitic acid. The lipid could be cleaved by PI-PLC digestion in vitro, and was identified by methanolysis and reverse phase thin layer chromatography of the products, as palmitoyldihydrosphingosine. Also, the free biosynthesized lipids were investigated in parasites obtained after 0, 24, 48 and 72 h differentiation of trypomastigotes and further incubated with
3Hpalmitic acid for 2 h. A maximum of free ceramide was found in the 24 h point, in accordance with the maximum of amastigote forms. In contrast only traces of free ceramide were found in trypomastigotes. The major ceramide (more than 90%) is palmitoyldihydrosphingosine, which is the same as found in the anchor of Ssp-4. The ceramide could play an important role in the cell biology of the parasite as previously found for mammalian cells.
We have detected several periodicities in the solar equatorial rotation rate of sunspot groups in the Greenwich Photoheliographic Results (GPR) during the period 1931-1976, the Solar Optical ...Observing Network (SOON) during the period 1977-2014, and the Debrecen Photoheliographic Data (DPD) during the period 1974-2014. Our results suggest a ~250-day period in the equatorial rotation rate determined from both the Mt. Wilson Doppler-velocity data and the sunspot-group data during 1986-2007. However, a wavelet analysis reveals that this periodicity appears mostly around 1991 in the velocity data, while it is present in most of the solar cycles covered by the sunspot-group data, mainly near the minimum epochs of the solar cycles. We also found the signature of a period of ~1.4 years period in the velocity data during 1990-1995, and in the equatorial rotation rate of sunspot groups mostly around the year 1956. The equatorial rotation rate of sunspot groups reveals a strong ~1.6-year periodicity around 1933 and 1955 and a weaker one around 1976, and a strong ~1.8-year periodicity around 1943. Our analysis also suggests periodicities of ~5 years, ~7 years, and ~17 years as well as some other short-term periodicities. However, short-term periodicities are mostly present at the time of solar minima. Hence, short-term periodicities cannot be confirmed because of the larger uncertainty in the data.
The total solar irradiance (TSI) varies on timescales of minute to centuries. On short timescales it varies due to the superposition of intensity fluctuations produced by turbulent convection and ...acoustic oscillations. On longer scale times, it changes due to photospheric magnetic activity, mainly because of the facular brightenings and dimmings caused by sunspots. While modern TSI variations have been monitored from space since 1970s, TSI variations over much longer periods can only be estimated using either historical observations of magnetic features, possibly supported by flux transport models, or from the measurements of the cosmogenic isotope (e.g., \textsuperscript{14}C or \textsuperscript{10}Be) concentrations in tree rings and ice cores. The reconstruction of the TSI in the last few centuries, particularly in the 17th/18th centuries during the Maunder minimum, is of primary importance for studying climatic effects. To separate the temporal components of the irradiance variations, specifically the magnetic cycle from secular variability, we decomposed the signals associated with historical observations of magnetic features and the solar modulation potential \(\Phi\) by applying an Empirical Mode Decomposition algorithm. Thus, the reconstruction is empirical and does not require any feature contrast or field transport model. The assessed difference between the mean value during the Maunder minimum and the present value is \(\simeq2.5 Wm^{-2}\). Moreover it shows, in the first half of the last century, a growth of \(\simeq 1.5 W m^{-2}\) which stops around the middle of the century to remain constant for the next 50 years, apart from the modulation due to the solar cycle.
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