We applied a fusion of CRISPR-Cas9 and activation-induced cytidine deaminase (Target-AID) for point mutagenesis at genomic regions specified by single guide RNAs (sgRNAs) in two crop plants. In rice, ...we induced multiple herbicide-resistance point mutations by multiplexed editing using herbicide selection, while in tomato we generated marker-free plants with homozygous heritable DNA substitutions, demonstrating the feasibility of base editing for crop improvement.
Single-photon detection is a requisite technique in quantum-optics experiments in both the optical and the microwave domains. However, the energy of microwave quanta are four to five orders of ...magnitude less than their optical counterpart, making the efficient detection of single microwave photons extremely challenging. Here we demonstrate the detection of a single microwave photon propagating through a waveguide. The detector is implemented with an impedance-matched artificial Λ system comprising the dressed states of a driven superconducting qubit coupled to a microwave resonator. Each signal photon deterministically induces a Raman transition in the Λ system and excites the qubit. The subsequent dispersive readout of the qubit produces a discrete 'click'. We attain a high single-photon-detection efficiency of 0.66±0.06 with a low dark-count probability of 0.014±0.001 and a reset time of ∼400 ns. This detector can be exploited for various applications in quantum sensing, quantum communication and quantum information processing.
As teachers are responsible for responding instantaneously to students' statements and actions, the progress of the class, and their teaching purpose, they need to be able to engage in responsive ...teaching. Teachers obtain information about students' learning by observing them in the classroom, and subsequently make instructional decisions based on this information. Teachers need to be sensitive to student behaviors and respond accordingly, because there are students who follow the teacher's instructions and those who do not in every classroom. Skilled teachers may distribute their gaze over the entire class and discover off-task behaviors. So how does a teacher's visual processing and noticing ability develop? It is important to clarify this process for both experienced teachers and student teachers. Therefore, the purpose of this study was to investigate whether there is a difference in visual processing and the ability to notice off-task behaviors in class between teachers and student teachers through gaze analysis. Using an eye tracking device, 76 teachers and 147 student teachers were asked to watch a video, and gaze measurements were collected. In the video, students exhibiting off-task behaviors in class were prompted by their classroom teacher to participate in the lesson. After the video, the participants were asked if they could identify the students who had displayed off-task behaviors and whom the teachers had warned. The results showed that teachers gazed at students engaging in off-task behaviors in class more often and noticed them at a higher rate than student teachers did. These results may be attributed to differences in the experiences of visual processing of relevant information in the classroom between teachers and student teachers. Thus, the findings on teachers' visual processing by direct measurement of gaze will be able to contribute to teachers' development.
Heat transport in spin-boson systems near the thermal equilibrium is systematically investigated. An asymptotically exact expression for the thermal conductance in a low-temperature regime wherein ...transport is described via a co-tunneling mechanism is derived. This formula predicts the power-law temperature dependence of thermal conductance ∝ T 2 s + 1 for a thermal environment of spectral density with the exponent s. An accurate numerical simulation is performed using the quantum Monte Carlo method, and these predictions are confirmed for arbitrary thermal baths. Our numerical calculation classifies the transport mechanism, and shows that the non-interacting-blip approximation quantitatively describes thermal conductance in the incoherent transport regime.
Advances in single-photon sources (SPSs) and single-photon detectors (SPDs) promise unique applications in the field of quantum information technology. In this paper, we report long-distance quantum ...key distribution (QKD) by using state-of-the-art devices: a quantum-dot SPS (QD SPS) emitting a photon in the telecom band of 1.5 μm and a superconducting nanowire SPD (SNSPD). At the distance of 100 km, we obtained the maximal secure key rate of 27.6 bps without using decoy states, which is at least threefold larger than the rate obtained in the previously reported 50-km-long QKD experiment. We also succeeded in transmitting secure keys at the rate of 0.307 bps over 120 km. This is the longest QKD distance yet reported by using known true SPSs. The ultralow multiphoton emissions of our SPS and ultralow dark count of the SNSPD contributed to this result. The experimental results demonstrate the potential applicability of QD SPSs to practical telecom QKD networks.
Microbial flora is investigated to be related with neuropathological conditions in Alzheimer's disease (AD), and is attracting attention as a drug discovery resource. However, the relevance between ...the soil microbiota and the pathological condition has not been fully clarified due to the difficulty in isolation culture and the component complexity. In this study, we established a library of secondly metabolites produced in microorganism to investigate the potential effect of microorganisms on the production of amyloid β (Aβ), one of the most representative pathogens of AD. We conducted a library screening to quantify Aβ and neuronal toxicity by using cortical neurons from human induced pluripotent stem cells (iPSCs) of AD patients after adding secondary metabolites. Screening results and following assessment of dose-dependency identified Verrucarin A, produced in Myrothecium spp., showed 80% decrease in Aβ production. Furthermore, addition of Mer-A2026A, produced in Streptomyces pactum, showed increase in Aβ42/40 ratio at the low concentration, and decrease in Aβ production at the higher concentration. As a result, established library and iPSC-based phenotyping assay clarified a direct link between Aβ production and soil microorganisms. These results suggest that Aβ-microorganism interaction may provide insight into the AD pathophysiology with potential therapeutics.
Background & Aims Small nucleolar noncoding RNAs (snoRNAs) regulate function of ribosomes, and specific snoRNAs are dysregulated in some cancer cells. We investigated dysregulation of snoRNAs in ...pancreatic ductal adenocarcinoma (PDAC) cells. Methods We investigated snoRNA expression in PDAC cell lines by complementary DNA microarray and quantitative reverse transcription polymerase chain reaction. In PDAC (n = 133), intraductal papillary mucinous neoplasm (n = 16), mucinous cystic neoplasm-associated PDAC (n = 1), and non-tumor pancreas (n = 8) and liver (n = 3) tissues from subjects who underwent surgical resection, levels of snoRNA were measured by quantitative reverse transcription polymerase chain reaction and compared with clinicopathologic parameters and survival times determined by Kaplan−Meier analysis. To examine snoRNA function, PDAC cells were transfected with snoRNA-antisense oligonucleotides flanked with amido-bridged nucleic acids, or snoRNA-expression plasmids, and analyzed in proliferation, colony formation, spheroid formation, and invasion assays. To identify snoRNA-related factors, cells were analyzed by gene expression and proteomic profiling and immunoblot assays. Mice were given intrasplenic injections of MIA PaCa2- or Suit2-HLMC cells; tumor-bearing nude mice were then given 3 weekly injections of an antisense oligonucleotides against SNORA23, a H/ACA-box type snoRNA, and tumor growth and metastasis to liver, blood, and pancreas were analyzed. Results Levels of SNORA23 increased and accumulated at the nucleolus in highly metastatic MIA PaCa2- or Suit2-HLMC cells compared with their parental cells. We detected SNORA23 in human PDAC specimens but not in non-tumor pancreatic tissue. PDAC level of SNORA23 correlated with invasion grade and correlated inversely with disease-free survival time of patients. Expression of SNORA23 in PDAC cells increased their invasive activity and colony formation, and spheroid formation was inhibited by SNORA23 knockdown. In gene expression and proteomic profile analyses, we found SNORA23 to increase expression of spectrin repeat-containing nuclear envelope 2 (SYNE2) messenger RNA and protein. Knockdown of SYNE2 in PDAC cells reduced their invasive activities and anchor-independent survival. Administration of SNORA23 antisense oligonucleotides to mice slowed growth of xenograft tumors, tumor expression of SYNE2, tumor cell dissemination, and metastasis to liver. Conclusions We found expression of the snoRNA SNORA23, which mediates sequence-specific pseudouridylation of ribosomal RNAs, to be increased in human PDAC tissues compared with non-tumor tissues, and levels to correlate with tumor invasion grade and patient survival time. SNORA23 increases expression of SYNE2, possibly through modulation of ribosome biogenesis, to promote PDAC cell survival and invasion, and growth and metastasis of xenograft tumors in mice.
We investigate the heat flow of a qubit coupled to heat baths under continuous quantum measurement. In the steady-state limit, we show that heat always flows from the measurement apparatus into the ...qubit regardless of the measured qubit state and derive lower and upper bounds for the heat current between the qubit and the measurement apparatus. Furthermore, we study the transient dynamics of the heat current and the excess heat during the transient regime.
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