Superconducting proximity effect to the block antiferromagnetism in Ky_{y}Fe2−x_{2-x}Se2_{2}

Recent discovery of superconducting (SC) ternary iron selenides has block antiferromagentic (AFM) long range order. Many experiments show possible mesoscopic phase separation of the superconductivity and antiferromagnetism, while the neutron experiment reveals a sizable suppression of magnetic moment due to the superconductivity indicating a possible phase coexistence. Here we propose that the observed suppression of the magnetic moment may be explained due to the proximity effect within a phase separation scenario. We use a two-orbital model to study the proximity effect on a layer of block AFM state induced by neighboring SC layers via an interlayer tunneling mechanism. We argue that the proximity effect in ternary Fe-selenides should be large because of the large interlayer coupling and weak electron correlation. The result of our mean field theory is compared with the neutron experiments semi-quantitatively. The suppression of the magnetic moment due to the SC proximity effect is found to be more pronounced in the d-wave superconductivity and may be enhanced by the frustrated structure of the block AFM state.Comment: 6 pages, 6 figure

Theory for charge and orbital density-wave states in manganite La0.5_{0.5}Sr1.5_{1.5}MnO4_4

We investigate the high temperature phase of layered manganites, and demonstrate that the charge-orbital phase transition without magnetic order in La$_{0.5}$Sr$_{1.5}$MnO$_4$ can be understood in terms of the density wave instability. The orbital ordering is found to be induced by the nesting between segments of Fermi surface with different orbital characters. The simultaneous charge and orbital orderings are elaborated with a mean field theory. The ordered orbitals are shown to be $d_{x^2-y^2} \pm d_{3z^2-r^2}$.Comment: published versio

Recombinase-Based Genetic Circuit Optimization

International audienceThe rapid advancements of synthetic biology show promising potential in biomedical and other applications. Recently, recombinases were proposed as a tool to engineer genetic logic circuits with long-term memory in living and even mammalian cells. The technology is under active development, and the complexity of engineered genetic circuits grows continuously. However, how to minimize a genetic circuit composed of recombinase-based logic gates remain largely open. In this paper, we formulate the problem as a cubic-time assignment problem and solved by a 0/1-ILP solver to minimize DNA sequence length of genetic circuits. Experimental results show effective reduction of our optimization method, which may be crucial to enable practical realization of complex genetic circuits

The Performance of FAST with Ultra-Wide Bandwidth Receiver at 500-3300 MHz

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) has been running for several years. A new Ultra-Wide Bandwidth (UWB) receiver, simultaneously covering 500-3300 MHz, has been mounted in the FAST feed cabin and passed a series of observational tests. The whole UWB band is separated into four independent bands. Each band has 1048576 channels in total, resulted in a spectral resolution of 1 kHz. At 500-3300 MHz, the antenna gain is around 14.3-7.7 K/Jy, the aperture efficiency is around 0.56-0.30, the system temperature is around 88-130 K, and the HPBW is around 7.6-1.6 arcmin. The measured standard deviation of pointing accuracy is better than ~7.9 arcsec, when zenith angle (ZA) is within 26.4deg. The sensitivity and stability of the UWB receiver are confirmed to satisfy expectation by spectral observations, e.g., HI and OH. The FAST UWB receiver already has a good performance for taking sensitive observations in various scientific goals.Comment: 11 pages, 7 figures, 2 tables, submitted to Research in Astronomy and Astrophysic

Awareness research report of hematological disease gene detection in the clinical application

目的  探讨医务工作者对血液病基因检测临床应用的认知程度。方法  对参加“第三届陆道培血液病高峰论坛”的371名学者进行了以微信为平台的调查研究，调查内容涉及被调查者的基本信息、工作习惯以及他们对基因检测临床应用多方面的观点。结果  调查对象的年龄主要分布在40岁以下，基因检测在三甲医院或高水平专科医院内应用的频度较高，有32.36% 被调查者认为费用过高是基因检测临床应用最主要的制约因素，68.2% 调查对象可以容忍报告在5-10个工作日内出具，对于基因突变报告有49.1% 临床医生认为报告结果太复杂。结论  基因检测已经在临床诊断方面得到较为广泛的应用，尤其是三甲医院和高水平专科医院，费用、有明确临床意义的临床检测项目较少及时间是基因检测临床应用的主要制约因素，大部分临床医生希望基因检测报告可以在5-10个工作日内出具，并且认为报告结果太复杂。Objective: To investigate the cognition of the medical workers on hematological disease gene detection in the clinical application.  Methods: We investigated 371 scholars participating in the “Third Ludaopei Hematology Forum” through WeChat. Investigation contents include the basic information of respondents, work habits and their views on gene testing in clinical application. Results: The age of the respondents are mainly less than 40 years old. Genetic testing finds wide application in the tertiary hospitals and high level of specialized hospitals. 32.36% of respondents believe that genetic testing cost is the main factor restricting the clinical application; 68.2% respondents can tolerate the fact that report is issued at 5-10 working days. For gene mutations report, 49.1% clinical doctors think the results are too complicated. Conclusion: Genetic testing in clinical diagnosis has been more widely applied, especially for the tertiary hospitals and high level of specialized hospitals. The cost, time and the fewness of clinical testing programs which are clinically significant, are the main factors which restricted the clinical application of genetic testing. Most clinicians hope that genetic testing report will be issued at 5-10 working days, and deem that the results are too complicated.

Simple Security Proof of Mode-Pairing Quantum Key Distribution

Mode-pairing (MP) quantum key distribution (QKD) eliminates the requirements of phase locking and phase tracking compared with twin-field (TF) QKD while still surpassing the fundamental rate-distance limit of QKD. The complexity of the experimental implementation is reduced while the efficiency is also guaranteed. The security of MP-QKD is proved rigorously by examining the consistency of the states detailly between MP-QKD and the fixed-pairing scheme under all of Eve's possible interference, where the latter is equivalent to measurement-device-independent (MDI) QKD. Here we propose a simple and straightforward method to prove the information-theoretic security of MP-QKD. Specifically, an entanglement scheme for MP-QKD is proposed and its security is proved using entanglement purification. Then the security of MP-QKD can be guaranteed with the equivalence of the entanglement scheme and prepare-and-measure scheme for MP-QKD. With this approach, it is beneficial to analyze and understand the performance and security of MP-QKD. We explain why the pairing rounds in MP-QKD can be decoupled and determined by the measurement results announced by a third party, which is the key difference between MP-QKD and MDI-QKD. Moreover, we analyze the security of MP-QKD with the allowed optimal pairing strategy, which is significant for the secret key rate, under collective and coherent attacks