Storage of fiber-guided light in a nanofiber-trapped ensemble of cold atoms

Tapered optical fibers with a nanofiber waist are versatile tools for interfacing light and matter. In this context, laser-cooled atoms trapped in the evanescent field surrounding the optical nanofiber are of particular interest: They exhibit both long ground-state coherence times and efficient coupling to fiber-guided fields. Here, we demonstrate electromagnetically induced transparency, slow light, and the storage of fiber-guided optical pulses in an ensemble of cold atoms trapped in a nanofiber-based optical lattice. We measure a slow-down of light pulses to group velocities of 50 m/s. Moreover, we store optical pulses at the single photon level and retrieve them on demand in the fiber after 2 microseconds with an overall efficiency of (3.0 +/- 0.4) %. Our results show that nanofiber-based interfaces for cold atoms have great potential for the realization of building blocks for future optical quantum information networks

Offset frequency dynamics and phase noise properties of a self-referenced 10 GHz Ti:sapphire frequency comb

This paper shows the experimental details of the stabilization scheme that allows full control of the repetition rate and the carrier-envelope offset frequency of a 10 GHz frequency comb based on a femtosecond Ti:sapphire laser. Octave-spanning spectra are produced in nonlinear microstructured optical fiber, in spite of the reduced peak power associated with the 10 GHz repetition rate. Improved stability of the broadened spectrum is obtained by temperature-stabilization of the nonlinear optical fiber. The carrier-envelope offset frequency and the repetition rate are simultaneously frequency stabilized, and their short- and long-term stabilities are characterized. We also measure the transfer of amplitude noise of the pump source to phase noise on the offset frequency and verify an increased sensitivity of the offset frequency to pump power modulation compared to systems with lower repetition rate. Finally, we discuss merits of this 10 GHz system for the generation of low-phase-noise microwaves

The reverse protraction factor in the induction of bone sarcomas in radium-224 patients

More than 50 bone sarcomas have occurred among a collective of about 800 patients who had been injected in Germany after World War II with large activities of radium-224 for the intended treatment of bone tuberculosis and ankylosing spondylitis.^In an earlier analysis it was concluded that, at equal mean absorbed doses in the skeleton, patients with longer exposure time had a higher incidence of bone sarcomas.^The previous analysis was based on approximations; in particular, it did not account for the varying times at risk of the individual patients.^In view of the implications of a reverse protraction factor for basic considerations in radiation protection, the need was therefore felt to reevaluate the data from the continued follow-up by more rigorous statistical methods.^A first step of the analysis demonstrates the existence of the reverse dose-rate effect in terms of a suitably constructed rank-order test.^In a second step of the analysis it is concluded that the data are consistent with a linear no-threshold dose dependence under the condition of constant exposure time, while there is a steeper than linear dependence on dose when the exposure times increase proportionally to dose.^A maximum likelihood fit of the data is then performed in terms of a proportional hazards model that includes the individual parameters, dose, treatment duration, and age at treatment.^The fit indicates proportionality of the tumor rates to mean skeletal dose with an added factor (1 + 0.18.tau), where tau is the treatment time in months.^This indicates that a protraction of the injections over 15 months instead of 5 months doubles the risk of bone sarcoma

Structure formation by cosmic strings with a cosmological constant

Final published version.Comment: 4 Page

Dibenzo[a,g]quinolizin-8-ones: synthesis, estrogen receptor affinities, and cytostatic activity

A number of acetoxy-substituted dibenzo[a,g]quinolizin-8-ones were synthesized by the reaction of 1-oxoisoquinolines with substituted homophthalic acid anhydride. All of the derivatives with acetoxy groups in positions 3 and 10 bind to the estrogen receptor. Relative binding affinities (RBA) ranged from 1.8 to 5.6 (estradiol: RBA = 100) when the substituent at C-6 was a short alkyl group. Introduction of additional oxygen functions in the 2- and/or 11-position decreased binding affinities. Analyses of the enantiomers of 6-methyl (6b) and 6-ethyl (6c) derivatives revealed that the receptor binding is mainly due to one optical isomer (e.g. (-)-6b, 9.9; (+)-6b, 0.6). In hormone-sensitive human MCF-7 breast cancer cells, compounds with one acetoxy group in each aromatic ring strongly inhibited cellular growth. Despite marked differences in receptor affinity, the enantiomers displayed similar activities in this cell culture. In hormone-independent MDA-MB 231 mammary tumor cells, only a weak cytostatic effect was recorded at 10-5 M. In the immature mouse uterine weight test, minimal estrogenic activity was observed. At higher doses, a significant anti-estrogenic effect became evident. It is assumed that the estrogen antagonism is responsible for the specific cytostatic effect in MCF-7 breast cancer cells

An epidemiological assessment of lens opacifications that impaired vision in patients injected with radium-224

The incidence of lens opacifications that impaired vision (cataract) was analyzed among 831 patients who were injected with known dosages of 224Ra in Germany shortly after World War II. The dependence of the incidence on dosage, i.e., injected activity per unit body weight, and on time after treatment was determined. The observations are equally consistent with proportionality of the incidence of cataract to the square of dosage or with a linear dependence beyond a threshold of 0.5 MBq/kg. The possibility of a linear dependence without threshold was strongly rejected (P less than 0.001). The analysis of temporal dependences yielded a component that was correlated with the injected amount of 224Ra and a component that was uncorrelated. The former was inferred by a maximum likelihood analysis to increase approximately as the square of the time after treatment. The component unrelated to the treatment was found to increase steeply with age and to become dominant within the collective of patients between age 50 and 60. The relative magnitudes of the two components were such that a fraction of 55 to 60% of the total of 58 cataracts had to be ascribed to the dose-related incidence. Impaired vision due to cataract was diagnosed before age 54 in 25 cases. In terms of injected activity per unit body weight no dependence of the sensitivity on age was found; specifically there was no indication of a faster occurrence of the treatment-related cataracts in patients treated at older ages

BANANA IV: Two aligned stellar rotation axes in the young eccentric binary system EP Crucis: primordial orientation and tidal alignment

With observations of the EP Cru system, we continue our series of measurements of spin-orbit angles in eclipsing binary star systems, the BANANA project (Binaries Are Not Always Neatly Aligned). We find a close alignment between the sky projections of the rotational and orbital angular momentum vectors for both stars (beta_p = -1.8+-1.6 deg and |beta_s|<17 deg). We also derive precise absolute dimensions and stellar ages for this system. The EP Cru and DI Her systems provide an interesting comparison: they have similar stellar types and orbital properties, but DI Her is younger and has major spin-orbit misalignments, raising the question of whether EP Cru also had a large misalignment at an earlier phase of evolution. We show that tidal dissipation is an unlikely explanation for the good alignment observed today, because realignment happens on the same timescale as spin-orbit synchronization, and the stars in EP Cru are far from syncrhonization (they are spinning 9 times too quickly). Therefore it seems that some binaries form with aligned axes, while other superficially similar binaries are formed with misaligned axes.Comment: ApJ accepted, 10 pages, 7 figure