Long-term observations of Uranus and Neptune at 90 GHz with the IRAM 30m telescope - (1985 -- 2005)

The planets Uranus and Neptune with small apparent diameters are primary calibration standards. We investigate their variability at ~90 GHz using archived data taken at the IRAM 30m telescope during the 20 years period 1985 to 2005. We calibrate the planetary observations against non-variable secondary standards (NGC7027, NGC7538, W3OH, K3-50A) observed almost simultaneously. Between 1985 and 2005, the viewing angle of Uranus changed from south-pole to equatorial. We find that the disk brightness temperature declines by almost 10% (~2sigma) over this time span indicating that the south-pole region is significantly brighter than average. Our finding is consistent with recent long-term radio observations at 8.6 GHz by Klein & Hofstadter (2006). Both data sets do moreover show a rapid decrease of the Uranus brightness temperature during the year 1993, indicating a temporal, planetary scale change. We do not find indications for a variation of Neptune's brightness temperature at the 8% level. If Uranus is to be used as calibration source, and if accuracies better than 10% are required, the Uranus sub-earth point latitude needs to be taken into account.Comment: accepted for publication in A&

Temperature dependence of Raman vibrational bandwidths in poly(rA) and rAMP

Isotropic and anisotropic spontaneous Raman spectra were obtained from solutions of poly(ra) and rAMP in buffer. The temperature dependence of these spectra was measured to elucidate the influence of macromolecular dynamics and solvent dynamics on the bandwidths of base vibrations in the single stranded polynucleotide poly(rA). The temperature dependence of a bandwidth depends upon the particular vibration under study. The bands can for the larger part be described by Lorentz functions. When fitted by Voigt functions, maximally 10% of each bandprofile of the adenine base vibrations can be attributed to a Gaussian component. The second moment has been determined from the spectra for the 725 cm¿1 band. From the second moment and the bandwidth, we were able to deduce that the vibrational oscillator is in the fast modulation limit. The determined timescale (perturbation correlation time 0.13 ps) eliminate perturbations connected to long range diffusion like concentration fluctuations (timescale in the order of 10 ps). The spectra were analyzed by an extensive curve fitting procedure providing accurate bandparameters (position, width and integrated intensity). The 725 cm¿1 band of adenine has a bandwidth which is dependent upon the degree of polymerization. In RAMP it is 17.6 cm¿1, in stacked (i.e. low temperature 5°C) poly(rA) it is 11.5 cm¿1. The bandwidth of the adenine vibration at 1336 cm¿1 cm¿1 has a temperature dependence which is similar to the intensity changes of the Raman and the absorption hypochromic effect as a function of temperature. The melting transition can therefore be followed by the changes in bandwidth of suitable vibrations

A Raman spectroscopic study of the interaction between nucleotides and the DNA binding protein gp32 of bacteriophage T4

Raman spectra of the bacteriophage T4 denaturing protein gp32, its complex with the polynucleotides poly(rA), poly(dA), poly(dT), poly(rU), and poly(rC), and with the oligonucleotides (dA)8 and (dA)2, were recorded and interpreted. According to an analysis of the gp32 spectra with the reference intensity profiles of Alix and co-workers [M. Berjot, L. Marx, and A.J.P. Alix (1985) J. Ramanspectrosc., submitted; A.J.P. Alix, M. Berjot, and J. Marx (1985) in Spectroscopy of Biological Molecules, A. J. P. Alix, L. Bernard, and M. Manfait, Eds., pp. 149-154], 1 gp32 contains ≈ 45% helix, ≈ 40% β-sheet, and 15% undefined structure. Aggregation of gp32 at concentrations higher than 40 mg/mL leads to a coordination of the phenolic OH groups of 4-6 tyrosines and of all the sulfhydryl (SH) groups present in the protein with the COO- groups of protein. The latter coordination persists even at concentrations as low as 1 mg/mL. In polynucleotide-protein complexes the nucleotide shields the 4-6 tyrosine residues from coordination by the COO- groups even at high protein concentration. The presence of the nucleotide causes no shielding of the SH groups. With Raman difference spectroscopy it is shown that binding of the protein to a single-stranded nucleotide involves both tyrosine and trytophan residues. A change in the secondary structure of the protein upon binding is observed. In the complex, gp32 contains more -sheet structure than when uncomplexed. A comparison of the spectra of complexed poly(rA) and poly(dA) with the spectra of their solution conformations at 15°C reveals that in both polynucleotides the phosphodiester vibration changes upon complex formation in the same way as upon a transition from a regular to a more disordered conformation. Distortion of the phosphate-sugar-base conformation occurs upon complex formation, so that the spectra of poly(rA) and poly(dA) are more alike in the complex than they are in the free polynucleotides. The decrease in intensity of the Raman bands at 1304 cm-1 in poly(rA), at 1230 cm-1 in poly(rU), and at 1240 and 1378 cm-1 of poly(dT) may be indicative of increased stacking interactions in the complex. No influence of the nucleotide chain length upon the Raman spectrum of gp322 in the complex was detected. Both the nucleotide lines and the protein lines in the spectrum of a complex are identical in poly(dA) and (dA)8

350 Micron Observations of Ultraluminous Infrared Galaxies at Intermediate Redshifts

We present 350micron observations of 36 ultraluminous infrared galaxies (ULIRGs) at intermediate redshifts (0.089 <= z <= 0.926) using the Submillimeter High Angular Resolution Camera II (SHARC-II) on the Caltech Submillimeter Observatory (CSO). In total, 28 sources are detected at S/N >= 3, providing the first flux measurements longward of 100micron for a statistically significant sample of ULIRGs in the redshift range of 0.1 < z < 1.0. Combining our 350micron flux measurements with the existing IRAS 60 and 100micron data, we fit a single-temperature model to the spectral energy distribution (SED), and thereby estimate dust temperatures and far-IR luminosities. Assuming an emissivity index of beta = 1.5, we find a median dust temperature and far-IR luminosity of Td = 42.8+-7.1K and log(Lfir/Lsolar) = 12.2+-0.5, respectively. The far-IR/radio correlation observed in local star-forming galaxies is found to hold for ULIRGs in the redshift range 0.1 < z < 0.5, suggesting that the dust in these sources is predominantly heated by starbursts. We compare the far-IR luminosities and dust temperatures derived for dusty galaxy samples at low and high redshifts with our sample of ULIRGs at intermediate redshift. A general Lfir-Td relation is observed, albeit with significant scatter, due to differing selection effects and variations in dust mass and grain properties. The relatively high dust temperatures observed for our sample compared to that of high-z submillimeter-selected starbursts with similar far-IR luminosities suggest that the dominant star formation in ULIRGs at moderate redshifts takes place on smaller spatial scales than at higher redshifts.Comment: (24 pages in preprint format, 1 table, 7 figures, accepted for publication in ApJ

Inorganic separator for a high temperature silver-zinc battery

Electrode design, inorganic separators, and performance tests of multiplate five ampere-hour silver-zinc battery cel

Cluster analysis of flow cytometric list mode data on a personal computer

A cluster analysis algorithm, dedicated to analysis of flow cytometric data is described. The algorithm is written in Pascal and implemented on an MS-DOS personal computer. It uses k-means, initialized with a large number of seed points, followed by a modified nearest neighbor technique to reduce the large number of subclusters. Thus we combine the advantage of the k-means (speed) with that of the nearest neighbor technique (accuracy). In order to achieve a rapid analysis, no complex data transformations such as principal components analysis were used. \ud Results of the cluster analysis on both real and artificial flow cytometric data are presented and discussed. The results show that it is possible to get very good cluster analysis partitions, which compare favorably with manually gated analysis in both time and in reliability, using a personal computer

The MCGA (multiple cubic gradient approximation) method for the analysis of Raman spectra

An easily accessible interactive method for the analysis of Raman spectra consisting of many overlapping peaks is presented. A combination of a three- or four-dimensional grid and gradient searching is applied. The method can handle spectra with up to about 50 lines, based on a broad background. Analytical and user-defined or tabulated basic functions can be included. The merits of the method are discussed with both artificial and real spectra

A new principle of cell sorting by using selective electroporation in a modified flow cytometer

When a strong electric field pulse of a few microseconds is applied to biological cells, small pores are formed in the cell membranes; this process is called electroporation. At high field strengths and/or long pulse durations the membranes will be damaged permanently. This eventually leads to cell kill. \ud We have developed a modified flow cytometer in which one can electroporate individual cells selected by optical analysis. The first experiments with this flow cytometer were designed to use it as a damaging sorter; we used electric pulses of 10 s and resulting field strengths of 2.0 and 3.2 X 106 V/m to kill K562 cells and lymphocytes respectively. The hydrodynamically focused cells are first optically analyzed in the usual way in a square flow channel. At the end of this channel the cells are forced to flow through a small Coulter orifice, into a wider region. If optical analysis indicates that a cell is unwanted, the cell is killed by applying a strong electric field across the Coulter orifice. The wanted living cells can be subsequently separated from the dead cells and cell fragments by a method suitable for the particular application (e.g., centrifugation, cell growth, density gradient, etc.). \ud The results of these first experiments demonstrate that by using very simple equipment, sorting by selective killing with electric fields is possible at rates of 1,000 cells/s with a purity of the sorted fraction of 99.9%

Surface-enhanced Raman spectroscopy of DNA bases

A Raman microprobe has been used to measure the surface-enhanced Raman spectra of adenine, guanine, cytosine and thymine. Comparison of the SERS spectrum with solution spectra shows that some line positions are not influenced by the adsorption process while others show large shifts. In the SERS spectrum new lines, not visible in the solution spectrum, appear while some lines visible in the solution spectrum are not enhanced to a detectable level and are therefore not seen in SERS. The relative intensities are changed owing to an apparently vibration-dependent enhancement factor. A line-broadening effect occurs for most lines except carbonyl stretching vibrations in cytosine and thymine. All SERS spectra show increased contributions of bending vibrations and side-chain groups. In particular, amino group vibrations in adenine and cytosine are clearly visible. Comparison of the shape and intensity of the carbonyl stretching vibrations in cytosine, thymine and guanine show important differences. It is hypothesized that these differences indicate differences in the orientation of these groups with respect to the surface