The solar differential rotation in the 18th century

The sunspot drawings of Johann Staudacher of 1749--1799 were used to determine the solar differential rotation in that period. These drawings of the full disk lack any indication of their orientation. We used a Bayesian estimator to obtain the position angles of the drawings, the corresponding heliographic spot positions, a time offset between the drawings and the differential rotation parameter \delta\Omega, assuming the equatorial rotation period is the same as today. The drawings are grouped in pairs, and the resulting marginal distributions for \delta\Omega were multiplied. We obtain \delta\Omega=-0.048 \pm 0.025 d^-1 (-2.75^o/d) for the entire period. There is no significant difference to the value of the present Sun. We find an (insignificant) indication for a change of \delta\Omega throughout the observing period from strong differential rotation, \delta\Omega\approx -0.07 d^-1, to weaker differential rotation, \delta\Omega\approx-0.04 d^-1.Comment: 6 pages, 6 figures, accepted for Astronomy and Astrophysic

Superpositions of the Orbital Angular Momentum for Applications in Quantum Experiments

Two different experimental techniques for preparation and analyzing superpositions of the Gaussian and Laguerre-Gassian modes are presented. This is done exploiting an interferometric method on the one hand and using computer generated holograms on the other hand. It is shown that by shifting the hologram with respect to an incoming Gaussian beam different superpositions of the Gaussian and the Laguerre-Gaussian beam can be produced. An analytical expression between the relative phase and the amplitudes of the modes and the displacement of the hologram is given. The application of such orbital angular momenta superpositions in quantum experiments such as quantum cryptography is discussed.Comment: 18 pages, 4 figures. to appear in Journal of Optics

Bose-Einstein condensation in a stiff TOP trap with adjustable geometry

We report on the realisation of a stiff magnetic trap with independently adjustable trap frequencies, $\omega_z$ and $\omega_r$, in the axial and radial directions respectively. This has been achieved by applying an axial modulation to a Time-averaged Orbiting Potential (TOP) trap. The frequency ratio of the trap, $\omega_z / \omega_r$, can be decreased continuously from the original TOP trap value of 2.83 down to 1.6. We have transferred a Bose-Einstein condensate (BEC) into this trap and obtained very good agreement between its observed anisotropic expansion and the hydrodynamic predictions. Our method can be extended to obtain a spherical trapping potential, which has a geometry of particular theoretical interest.Comment: 4 pages, 3 figure

KRb Feshbach Resonances: Modeling the interatomic potential

We have observed 28 heteronuclear Feshbach resonances in 10 spin combinations of the hyperfine ground states of a 40K 87Rb mixture. The measurements were performed by observing the loss rates from an atomic mixture at magnetic fields between 0 and 700 G. This data was used to significantly refine an interatomic potential derived from molecular spectroscopy, yielding a highly consistent model of the KRb interaction. Thus, the measured resonances can be assigned to the corresponding molecular states. In addition, this potential allows for an accurate calculation of the energy differences between highly excited levels and the rovibrational ground level. This information is of particular relevance for the formation of deeply bound heteronuclear molecules. Finally, the model is used to predict Feshbach resonances in mixtures of 87Rb combined with 39K or 41K.Comment: 4 pages, 3 figure

Linking environmental carcinogen exposure to TP53 mutations in human tumours using the human TP53 knock-in (Hupki) mouse model

TP53 is one of the most commonly mutated genes in human tumours. Variations in the types and frequencies of mutations at different tumour sites suggest that they may provide clues to the identity of the causative mutagenic agent. A useful model for studying human TP53 mutagenesis is the partial human TP53 knock-in (Hupki) mouse containing exons 4-9 of human TP53 in place of the corresponding mouse exons. For an in vitro assay, embryo fibroblasts from the Hupki mouse can be examined for the generation and selection of TP53 mutations because mouse cells can be immortalized by mutation of Tp53 alone. Thus far, four environmental carcinogens have been examined using the Hupki embryo fibroblast immortalization assay: (a) UV light, which is linked to human skin cancer; (b) benzo[a] pyrene, which is associated with tobacco smoke-induced lung cancer; (c) 3-nitrobenzanthrone, a suspected human lung carcinogen linked to diesel exposure; and (d) aristolochic acid, which is linked to Balkan endemic nephropathy-associated urothelial cancer. In each case, a unique TP53 mutation pattern was generated that corresponded to the pattern found in human tumours where exposure to these agents has been documented. Therefore, the Hupki embryo fibroblast immortalization assay has sufficient specificity to make it applicable to other environmental mutagens that putatively play a role in cancer aetiology. Despite the utility of the current Hupki embryo fibroblast immortalization assay, it has several limitations that could be addressed by future developments, in order to improve its sensitivity and selectivity

Extended coherence time on the clock transition of optically trapped Rubidium

Optically trapped ensembles are of crucial importance for frequency measurements and quantum memories, but generally suffer from strong dephasing due to inhomogeneous density and light shifts. We demonstrate a drastic increase of the coherence time to 21 s on the magnetic field insensitive clock transition of Rb-87 by applying the recently discovered spin self-rephasing. This result confirms the general nature of this new mechanism and thus shows its applicability in atom clocks and quantum memories. A systematic investigation of all relevant frequency shifts and noise contributions yields a stability of 2.4E-11 x tau^(-1/2), where tau is the integration time in seconds. Based on a set of technical improvements, the presented frequency standard is predicted to rival the stability of microwave fountain clocks in a potentially much more compact setup.Comment: 5 pages, 4 figure

Impaired hepatic drug and steroid metabolism in congenital adrenal hyperplasia due to P450 oxidoreductase deficiency

Objective: Patients with congenital adrenal hyperplasia due to P450 oxidoreductase (POR) deficiency(ORD) present with disordered sex development and glucocorticoid deficiency. This is due to disruption of electron transfer from mutant POR to microsomal cytochrome P450 (CYP) enzymes that play a key role in glucocorticoid and sex steroid synthesis. POR also transfers electrons to all major drugmetabolizing CYP enzymes, including CYP3A4 that inactivates glucocorticoid and oestrogens. However, whether ORD results in impairment of in vivo drug metabolism has never been studied. Design:We studied an adult patient with ORD due to homozygous POR A287P, the most frequent POR mutation in Caucasians, and her clinically unaffected, heterozygous mother. The patient had received standard dose oestrogen replacement from 17 until 37 years of age when it was stopped after she developed breast cancer. Methods: Both subjects underwent in vivo cocktail phenotyping comprising the oral administration of caffeine, tolbutamide, omeprazole, dextromethorphan hydrobromide and midazolam to assess the five major drug-metabolizing CYP enzymes. We also performed genotyping for variant CYP alleles known to affect drug metabolism. Results: Though CYP enzyme genotyping predicted normal or high enzymatic activities in both subjects, in vivo assessment showed subnormal activities of CYP1A2, CYP2C9, CYP2D6 and CYP3A4 in the patient and of CYP1A2 and CYP2C9 in her mother. Conclusions: Our results provide in vivo evidence for an important role of POR in regulating drug metabolism and detoxification. In patients with ORD, in vivo assessment of drug-metabolizing activities with subsequent tailoring of drug therapy and steroid replacement should be considered

Meteor light curves: the relevant parameters

We investigate a uniform sample of 113 light curves (LCs) of meteors collected at the Wise Observatory in November 2002 while observing the Leonid meteor shower. We use previously defined descriptors such as the skewness F and a recently defined pointedness parameter along with a number of other measurable or derived quantities to explore the parameter space in search of meaningful LC descriptors. We make extensive use of statistical techniques to reveal links among the variables and to understand their relative importance. In particular, we show that meteors with long-duration trails rise slowly to their maximal brightness and also decay slowly from there while showing milder flaring than other meteors. Early skewed LCs show a fast rise to the peak. We show that the duration of te luminous phase of the meteor is th emost important variable differentiating among the 2002 LCs. The skewness parameter F appears only as the 2nd or 3rd in explaining the LC variance. We suggest that the pointedness parameter P could possibly be useful to discriminate among meteors from different showers, or to compare observations and model predictions.Comment: 10 pages (2 figures) in press with MNRA

Radio frequency association of heteronuclear Feshbach molecules

We present a detailed analysis of the production efficiency of weakly bound heteronuclear KRb-Feshbach molecules using radio frequency association in a harmonic trap. The efficiency was measured in a wide range of temperatures, binding energies and radio frequencies. A comprehensive analytical model is presented, explaining the observed asymmetric spectra and achieving good quantitative agreement with the measured production rates. This model provides a deep understanding of the molecule association process and paves the way for future experiments which rely on Feshbach molecules e.g. for the production of deeply bound molecules.Comment: 5 pages, 4 figure

Width of Sunspot Generating Zone and Reconstruction of Butterfly Diagram

Based on the extended Greenwich-NOAA/USAF catalogue of sunspot groups it is demonstrated that the parameters describing the latitudinal width of the sunspot generating zone (SGZ) are closely related to the current level of solar activity, and the growth of the activity leads to the expansion of SGZ. The ratio of the sunspot number to the width of SGZ shows saturation at a certain level of the sunspot number, and above this level the increase of the activity takes place mostly due to the expansion of SGZ. It is shown that the mean latitudes of sunspots can be reconstructed from the amplitudes of solar activity. Using the obtained relations and the group sunspot numbers by Hoyt and Schatten (1998), the latitude distribution of sunspot groups ("the Maunder butterfly diagram") for the 18th and the first half of the 19th centuries is reconstructed and compared with historical sunspot observations.Comment: 16 pages, 11 figures; accepted by Solar Physics; the final publication will be available at www.springerlink.co