A noise-immune cavity-assisted non-destructive detection for an optical lattice clock in the quantum regime

We present and implement a non-destructive detection scheme for the transition probability readout of an optical lattice clock. The scheme relies on a differential heterodyne measurement of the dispersive properties of lattice-trapped atoms enhanced by a high finesse cavity. By design, this scheme offers a 1st order rejection of the technical noise sources, an enhanced signal-to-noise ratio, and an homogeneous atom-cavity coupling. We theoretically show that this scheme is optimal with respect to the photon shot noise limit. We experimentally realize this detection scheme in an operational strontium optical lattice clock. The resolution is on the order of a few atoms with a photon scattering rate low enough to keep the atoms trapped after detection. This scheme opens the door to various different interrogations protocols, which reduce the frequency instability, including atom recycling, zero-dead time clocks with a fast repetition rate, and sub quantum projection noise frequency stability

Polarizabilities of the 87Sr Clock Transition

In this paper, we propose an in-depth review of the vector and tensor polarizabilities of the two energy levels of the 87Sr clock transition whose measurement was reported in [P. G. Westergaard et al., Phys. Rev. Lett. 106, 210801 (2011)]. We conduct a theoretical calculation that reproduces the measured coefficients. In addition, we detail the experimental conditions used for their measurement in two Sr optical lattice clocks, and exhibit the quadratic behaviour of the vector and tensor shifts with the depth of the trapping potential and evaluate their impact on the accuracy of the clock

Gating by Cyclic Gmp and Voltage in the α Subunit of the Cyclic Gmp–Gated Channel from Rod Photoreceptors

Gating by cGMP and voltage of the α subunit of the cGMP-gated channel from rod photoreceptor was examined with a patch-clamp technique. The channels were expressed in Xenopus oocytes. At low [cGMP] (<20 μM), the current displayed strong outward rectification. At low and high (700 μM) [cGMP], the channel activity was dominated by only one conductance level. Therefore, the outward rectification at low [cGMP] results solely from an increase in the open probability, Po. Kinetic analysis of single-channel openings revealed two exponential distributions. At low [cGMP], the larger Po at positive voltages with respect to negative voltages is caused by an increased frequency of openings in both components of the open-time distribution. In macroscopic currents, depolarizing voltage steps, starting from −100 mV, generated a time-dependent current that increased with the step size (activation). At low [cGMP] (20 μM), the degree of activation was large and the time course was slow, whereas at saturating [cGMP] (7 mM) the respective changes were small and fast. The dose–response relation at −100 mV was shifted to the right and saturated at significantly lower Po values with respect to that at +100 mV (0.77 vs. 0.96). Po was determined as function of the [cGMP] (at +100 and −100 mV) and voltage (at 20, 70, and 700 μM, and 7 mM cGMP). Both relations could be fitted with an allosteric state model consisting of four independent cGMP-binding reactions and one voltage-dependent allosteric opening reaction. At saturating [cGMP] (7 mM), the activation time course was monoexponential, which allowed us to determine the individual rate constants for the allosteric reaction. For the rapid rate constants of cGMP binding and unbinding, lower limits are determined. It is concluded that an allosteric model consisting of four independent cGMP-binding reactions and one voltage-dependent allosteric reaction, describes the cGMP- and voltage-dependent gating of cGMP-gated channels adequately

Islam Progresif dalam Gerakan Sosial Dawam Rahardjo (1942-2016)

The phenomenon of poverty and injustice that continues until now, making a lot of Muslim figures to think again about Islamic thought. The Indonesian Islamic figure, one of the serious discussions of this issue is M. Dawam Rahardjo—for instance, we called Dawam. Based on the problem, this study focuses on the concept of thinking and implementation of Progressive Islam Dawam by reviewing, analyze, and discussing his work with a historical sociological approach. This research is descriptive-analytical with the qualitative method which is reinforced through in-depth interview. The results show that Dawam’s thought is part of Progressive Islam. He accepted the reality of the modern world, such as pluralism, liberalism, and secularism, then embraced all three in the strengthening of religiosity in society. Dawam is one of the Islamic leaders who have contributed to social change. Implementation can be seen from various works that concern Islamic renewal and community empowerment. His attitude and behavior can be seen in the institutions he leads—LSAF (Lembaga Studi Agama dan Filsafat) and LP3ES (Lembaga Penelitian, Pendidikan dan Penerangan Ekonomi dan Sosial). His criticism of the unjust political-economic order, accompanied by various solutions offered. Dawam’s idea in stemming the economic system that harms small people is the concept of cooperative development. Dawam chose the path of civil society and avoided political pragmatism. According to him, the Islamic struggle in the political path only tends to exploit religion for sectarian interests.Fenomena kemiskinan dan ketidakadilan yang masih berlanjut hingga saat ini, membuat banyak tokoh muslim berpikir ulang mengenai pemikiran keislaman. Tokoh Islam Indonesia, salah satu yang serius membincang persoalan ini adalah M. Dawam Rahardjo—selanjutnya Dawam. Berdasarkan soal tersebut, kajian ini fokus pada konsep pemikiran dan implementasi Islam Progresif Dawam dengan menelaah, mengkaji, dan membahas karyanya dengan pendekatan historissosiologis. Penelitian ini bersifat deskriptif-analitis dengan metode kualitatif yang diperkuat melalui wawancara mendalam. Hasilnya menunjukkan bahwa pemikiran Dawam bagian dari Islam Progresif. Ia menerima kenyataan dunia modern, seperti pluralisme, liberalisme, dan sekularisme, kemudian merengkuh ketiganya dalam penguatan keberagamaan di masyarakat. Dawam adalah salah satu tokoh Islam  yang memiliki andil dalam perubahan sosial. Implementasinya bisa dilihat dari berbagai karya yang concern pada pembaharuan Islam dan pemberdayaan masyarakat. Sikap dan perilakunya, dapat dilihat dalam lembaga yang ia pimpin—LSAF (Lembaga Studi Agama dan Filsafat) dan LP3ES (Lembaga Penelitian, Pendidikan dan Penerangan Ekonomi dan Sosial). Kritiknya atas tatanan ekonomi politik yang tidak adil, diiringi dengan berbagai solusi yang ditawarkan. Gagasan Dawam dalam membendung sistem ekonomi yang merugikan rakyat kecil adalah konsep pembangunan koperasi. Dawam milih jalur civil society, dan menghindari pragmatisme politik. Menurutnya, perjuangan keislaman di jalur politik hanya cenderung mengeksploitasi agama untuk kepentingan sektarian

A preclinical microbeam facility with a conventional x-ray tube.

Purpose Microbeam radiation therapy is an innovative treatment approach in radiation therapy that uses arrays of a few tens of micrometer wide and a few hundreds of micrometer spaced planar x-ray beams as treatment fields. In preclinical studies these fields efficiently eradicated tumors while normal tissue could effectively be spared. However, development and clinical application of microbeam radiation therapy is impeded by a lack of suitable small scale sources. Until now, only large synchrotrons provide appropriate beam properties for the production of microbeams.Methods In this work, a conventional x-ray tube with a small focal spot and a specially designed collimator are used to produce microbeams for preclinical research. The applicability of the developed source is demonstrated in a pilot in vitro experiment. The properties of the produced radiation field are characterized by radiochromic film dosimetry.Results 50 μm wide and 400 μm spaced microbeams were produced in a 20 × 20 mm2 sized microbeam field. The peak to valley dose ratio ranged from 15.5 to 30, which is comparable to values obtained at synchrotrons. A dose rate of up to 300 mGy/s was achieved in the microbeam peaks. Analysis of DNA double strand repair and cell cycle distribution after in vitro exposures of pancreatic cancer cells (Panc1) at the x-ray tube and the European Synchrotron leads to similar results. In particular, a reduced G2 cell cycle arrest is observed in cells in the microbeam peak region.Conclusions At its current stage, the source is restricted to in vitro applications. However, moderate modifications of the setup may soon allow in vivo research in mice and rats

Large atom number dual-species magneto-optical trap for fermionic 6Li and 40K atoms

We present the design, implementation and characterization of a dual-species magneto-optical trap (MOT) for fermionic 6Li and 40K atoms with large atom numbers. The MOT simultaneously contains 5.2x10^9 6Li-atoms and 8.0x10^9 40K-atoms, which are continuously loaded by a Zeeman slower for 6Li and a 2D-MOT for 40K. The atom sources induce capture rates of 1.2x10^9 6Li-atoms/s and 1.4x10^9 40K-atoms/s. Trap losses due to light-induced interspecies collisions of ~65% were observed and could be minimized to ~10% by using low magnetic field gradients and low light powers in the repumping light of both atomic species. The described system represents the starting point for the production of a large-atom number quantum degenerate Fermi-Fermi mixture

A Point Mutation in the Pore Region Alters Gating, Ca2+Blockage, and Permeation of Olfactory Cyclic Nucleotide–Gated Channels

Upon stimulation by odorants, Ca2+ and Na+ enter the cilia of olfactory sensory neurons through channels directly gated by cAMP. Cyclic nucleotide–gated channels have been found in a variety of cells and extensively investigated in the past few years. Glutamate residues at position 363 of the α subunit of the bovine retinal rod channel have previously been shown to constitute a cation-binding site important for blockage by external divalent cations and to control single-channel properties. It has therefore been assumed, but not proven, that glutamate residues at the corresponding position of the other cyclic nucleotide–gated channels play a similar role. We studied the corresponding glutamate (E340) of the α subunit of the bovine olfactory channel to determine its role in channel gating and in permeation and blockage by Ca2+ and Mg2+. E340 was mutated into either an aspartate, glycine, glutamine, or asparagine residue and properties of mutant channels expressed in Xenopus laevis oocytes were measured in excised patches. By single-channel recordings, we demonstrated that the open probabilities in the presence of cGMP or cAMP were decreased by the mutations, with a larger decrease observed on gating by cAMP. Moreover, we observed that the mutant E340N presented two conductance levels. We found that both external Ca2+ and Mg2+ powerfully blocked the current in wild-type and E340D mutants, whereas their blockage efficacy was drastically reduced when the glutamate charge was neutralized. The inward current carried by external Ca2+ relative to Na+ was larger in the E340G mutant compared with wild-type channels. In conclusion, we have confirmed that the residue at position E340 of the bovine olfactory CNG channel is in the pore region, controls permeation and blockage by external Ca2+ and Mg2+, and affects channel gating by cAMP more than by cGMP

An all-solid-state laser source at 671 nm for cold atom experiments with lithium

We present an all solid-state narrow line-width laser source emitting $670\,\mathrm{mW}$ output power at $671\,\mathrm{nm}$ delivered in a diffraction-limited beam. The \linebreak source is based on a fre-quency-doubled diode-end-linebreak pumped ring laser operating on the ${^4F}_{3/2} \rightarrow {^4I}_{13/2}$ transition in Nd:YVO$_4$. By using periodically-poled po-tassium titanyl phosphate (ppKTP) in an external build-up cavity, doubling efficiencies of up to 86% are obtained. Tunability of the source over $100\,\rm GHz$ is accomplished. We demonstrate the suitability of this robust frequency-stabilized light source for laser cooling of lithium atoms. Finally a simplified design based on intra-cavity doubling is described and first results are presented