In-Situ Dual-Port Polarization Contrast Imaging of Faraday Rotation in a High Optical Depth Ultracold 87Rb Atomic Ensemble

We study the effects of high optical depth and density on the performance of a light-atom quantum interface. An in-situ imaging method, a dual-port polarization contrast technique, is presented. This technique is able to compensate for image distortions due to refraction. We propose our imaging method as a tool to characterize atomic ensembles for high capacity spatial multimode quantum memories. Ultracold dense inhomogeneous Rubidium samples are imaged and we find a resonant optical depth as high as 680 on the D1 line. The measurements are compared with light-atom interaction models based on Maxwell-Bloch equations. We find that an independent atom assumption is insufficient to explain our data and present corrections due to resonant dipole-dipole interactions

Prospects of a superradiant laser based on a thermal or guided beam of Sr-88

The prospects of superradiant lasing on the 7.5 kHz wide $^1$S$_0$-$^3$P$_1$ transition in $^{88}$Sr is explored by using numerical simulations of two systems based on realistic experimental numbers. One system uses the idea of demonstrating continuous superradiance in a simple, hot atom beam with high flux, and the other system is based on using ultra-cold atoms in a dipole guide. We find that the hot beam system achieves lasing above a flux of $2.5 \times 10^{12}$ atoms/s. It is capable of outputting hundreds of nW and suppressing cavity noise by a factor of 20-30. The second order Doppler shift causes a shift in the lasing frequency on the order of 500 Hz. For the cold atom beam we account for decoherence and thermal effects when using a repumping scheme for atoms confined in a dipole guide. We find that the output power is on the order of hundreds of pW, however the second order Doppler shift can be neglected, and cavity noise can be suppressed on the order of a factor 50-100. Additionally we show that both systems exhibit local insensitivity to fluctuations in atomic flux.Comment: 10 pages, 7 figure

High-Field Optical Cesium Magnetometer for Magnetic Resonance Imaging

We present a novel high-field optical quantum magnetometer based on saturated absorption spectroscopy on the extreme angular-momentum states of the cesium D2 line. With key features including continuous readout, high sampling rate, and sensitivity and accuracy in the ppm-range, it represents a competitive alternative to conventional techniques for measuring magnetic fields of several teslas. The prototype has four small separate field probes, and all support electronics and optics are fitted into a single 19-inch rack to make it compact, mobile, and robust. The field probes are fiber coupled and made from non-metallic components, allowing them to be easily and safely positioned inside a 7 T MRI scanner. We demonstrate the capabilities of this magnetometer by measuring two different MRI sequences, and we show how it can be used to reveal imperfections in the gradient coil system, to highlight the potential applications in medical MRI. We propose the term EXAAQ (EXtreme Angular-momentum Absorption-spectroscopy Quantum) magnetometry, for this novel method.Comment: Corrected a minor mistake in affiliation

Dipole force free optical control and cooling of nanofiber trapped atoms

The evanescent field surrounding nanoscale optical waveguides offers an efficient interface between light and mesoscopic ensembles of neutral atoms. However, the thermal motion of trapped atoms, combined with the strong radial gradients of the guided light, leads to a time-modulated coupling between atoms and the light mode, thus giving rise to additional noise and motional dephasing of collective states. Here, we present a dipole force free scheme for coupling of the radial motional states, utilizing the strong intensity gradient of the guided mode and demonstrate all-optical coupling of the cesium hyperfine ground states and motional sideband transitions. We utilize this to prolong the trap lifetime of an atomic ensemble by Raman sideband cooling of the radial motion which, to the best of our knowledge, has not been demonstrated in nano-optical structures previously. This Letter points towards full and independent control of internal and external atomic degrees of freedom using guided light modes only

Multi Mode Interferometer for Guided Matter Waves

We describe the fundamental features of an interferometer for guided matter waves based on Y-beam splitters and show that, in a quasi two-dimensional regime, such a device exhibits high contrast fringes even in a multi mode regime and fed from a thermal source.Comment: Final version (accepted to PRL

Caspase-8-mediated PAR-4 cleavage is required for TNFα-induced apoptosis

The tumor suppressor protein prostate apoptosis response-4 (PAR-4) is silenced in a subset of human cancers and its down-regulation serves as a mechanism for cancer cell survival following chemotherapy. PAR-4 re-expression selectively causes apoptosis in cancer cells but how its pro-apoptotic functions are controlled and executed precisely is currently unknown. We demonstrate here that UV-induced apoptosis results in a rapid caspase-dependent PAR-4 cleavage at EEPD131¯G, a sequence that was preferentially recognized by caspase-8. To investigate the effect on cell growth for this cleavage event we established stable cell lines that express wild-type-PAR-4 or the caspase cleavage resistant mutant PAR-4 D131G under the control of a doxycycline-inducible promoter. Induction of the wild-type protein but not the mutant interfered with cell proliferation, predominantly through induction of apoptosis. We further demonstrate that TNFα-induced apoptosis leads to caspase-8-dependent PAR-4-cleavage followed by nuclear accumulation of the C-terminal PAR-4 (132-340) fragment, which then induces apoptosis. Taken together, our results indicate that the mechanism by which PAR-4 orchestrates the apoptotic process requires cleavage by caspase-8

Pharmacokinetics and biodistribution of Erufosine in nude mice - implications for combination with radiotherapy

<p>Abstract</p> <p>Background</p> <p>Alkylphosphocholines represent promising antineoplastic drugs that induce cell death in tumor cells by primary interaction with the cell membrane. Recently we could show that a combination of radiotherapy with Erufosine, a paradigmatic intravenously applicable alkylphosphocholine, <it>in vitro </it>leads to a clear increase of irradiation-induced cell death. In view of a possible combination of Erufosine and radiotherapy <it>in vivo </it>we determined the pharmacokinetics and bioavailability as well as the tolerability of Erufosine in nude mice.</p> <p>Methods</p> <p>NMRI (nu/nu) nude mice were treated by intraperitoneal or subcutaneous injections of 5 to 40 mg/kg body weight Erufosine every 48 h for one to three weeks. Erufosine-concentrations were measured in brain, lungs, liver, small intestine, colon, spleen, kidney, stomach, adipoid tissue, and muscle by tandem-mass spectroscopy. Weight course, blood cell count and clinical chemistry were analyzed to evaluate general toxicity.</p> <p>Results</p> <p>Intraperitoneal injections were generally well tolerated in all dose groups but led to a transient loss of the bodyweight (<10%) in a dose dependent manner. Subcutaneous injections of high-dose Erufosine caused local reactions at the injection site. Therefore, this regimen at 40 mg/kg body weight Erufosine was stopped after 14 days. No gross changes were observed in organ weight, clinical chemistry and white blood cell count in treated compared to untreated controls except for a moderate increase in lactate dehydrogenase and aspartate-aminotransferase after intensive treatment. Repeated Erufosine injections resulted in drug-accumulation in different organs with maximum concentrations of about 1000 nmol/g in spleen, kidney and lungs.</p> <p>Conclusion</p> <p>Erufosine was well tolerated and organ-concentrations surpassed the cytotoxic drug concentrations <it>in vitro</it>. Our investigations establish the basis for a future efficacy testing of Erufosine in xenograft tumor models in nude mice alone and in combination with chemo- or radiotherapy.</p

Phosphonate as a Stable Zinc-Binding Group for "Pathoblocker" Inhibitors of Clostridial Collagenase H (ColH)

Microbial infections are a significant threat to public health, and resistance is on the rise, so new antibiotics with novel modes of action are urgently needed. The extracellular zinc metalloprotease collagenase H (ColH) from Clostridium histolyticum is a virulence factor that catalyses tissue damage, leading to improved host invasion and colonisation. Besides the major role of ColH in pathogenicity, its extracellular localisation makes it a highly attractive target for the development of new antivirulence agents. Previously, we had found that a highly selective and potent thiol prodrug (with a hydrolytically cleavable thiocarbamate unit) provided efficient ColH inhibition. We now report the synthesis and biological evaluation of a range of zinc‐binding group (ZBG) variants of this thiol‐derived inhibitor, with the mercapto unit being replaced by other zinc ligands. Among these, an analogue with a phosphonate motif as ZBG showed promising activity against ColH, an improved selectivity profile, and significantly higher stability than the thiol reference compound, thus making it an attractive candidate for future drug development

Inter-rater reliability and aspects of validity of the parent-infant relationship global assessment scale (PIR-GAS)

Background: The Parent-Infant Relationship Global Assessment Scale (PIR-GAS) signifies a conceptually relevant development in the multi-axial, developmentally sensitive classification system DC:0-3R for preschool children. However, information about the reliability and validity of the PIR-GAS is rare. A review of the available empirical studies suggests that in research, PIR-GAS ratings can be based on a ten-minute videotaped interaction sequence. The qualification of raters may be very heterogeneous across studies. Methods: To test whether the use of the PIR-GAS still allows for a reliable assessment of the parent-infant relationship, our study compared a PIR-GAS ratings based on a full-information procedure across multiple settings with ratings based on a ten-minute video by two doctoral candidates of medicine. For each mother-child dyad at a family day hospital (N = 48), we obtained two video ratings and one full-information rating at admission to therapy and at discharge. This pre-post design allowed for a replication of our findings across the two measurement points. We focused on the inter-rater reliability between the video coders, as well as between the video and full-information procedure, including mean differences and correlations between the raters. Additionally, we examined aspects of the validity of video and full-information ratings based on their correlation with measures of child and maternal psychopathology. Results: Our results showed that a ten-minute video and full-information PIR-GAS ratings were not interchangeable. Most results at admission could be replicated by the data obtained at discharge. We concluded that a higher degree of standardization of the assessment procedure should increase the reliability of the PIR-GAS, and a more thorough theoretical foundation of the manual should increase its validity. <br