356 research outputs found
Ultimate low system dark count rate for superconducting nanowire single-photon detector
The dark count rate (DCR) is a key parameter of single-photon detectors. By
introducing a bulk optical band-pass filter mounted on a fiber-to-fiber optical
bench cooled at 3 K and blocking down to 5 micrometer, we suppressed the DCR of
a superconducting nanowire single-photon detector by more than three orders of
magnitude. The DCR is limited by the blackbody radiation through a signal
passband of 20 nm bandwidth. The figure of merit, system detection efficiency,
and DCR were 2.7 x 10^11, 2.3 %, and 0.001 Hz, respectively. Narrowing the
bandwidth to 100 GHz suppresses the DCR to 0.0001 Hz and the figure of merit
increases to 1.8 x 10^12.Comment: to appear in Optics Letter
Stimulation of DNA Glycosylase Activities by XPC Protein Complex: Roles of Protein-Protein Interactions
We showed that XPC complex, which is a DNA damage detector for nucleotide excision repair, stimulates activity of thymine DNA glycosylase (TDG) that initiates base excision repair. XPC appeared to facilitate the enzymatic turnover of TDG by promoting displacement from its own product abasic site, although the precise mechanism underlying this stimulation has not been clarified. Here we show that XPC has only marginal effects on the activity of E. coli TDG homolog (EcMUG), which remains bound to the abasic site like human TDG but does not significantly interacts with XPC. On the contrary, XPC significantly stimulates the activities of sumoylated TDG and SMUG1, both of which exhibit quite different enzymatic kinetics from unmodified TDG but interact with XPC. These results point to importance of physical interactions for stimulation of DNA glycosylases by XPC and have implications in the molecular mechanisms underlying mutagenesis and carcinogenesis in XP-C patients
Metropolitan Scale and Longitudinal Dataset of Anonymized Human Mobility Trajectories
Modeling and predicting human mobility trajectories in urban areas is an
essential task for various applications. The recent availability of large-scale
human movement data collected from mobile devices have enabled the development
of complex human mobility prediction models. However, human mobility prediction
methods are often trained and tested on different datasets, due to the lack of
open-source large-scale human mobility datasets amid privacy concerns, posing a
challenge towards conducting fair performance comparisons between methods. To
this end, we created an open-source, anonymized, metropolitan scale, and
longitudinal (90 days) dataset of 100,000 individuals' human mobility
trajectories, using mobile phone location data. The location pings are
spatially and temporally discretized, and the metropolitan area is undisclosed
to protect users' privacy. The 90-day period is composed of 75 days of
business-as-usual and 15 days during an emergency. To promote the use of the
dataset, we will host a human mobility prediction data challenge (`HuMob
Challenge 2023') using the human mobility dataset, which will be held in
conjunction with ACM SIGSPATIAL 2023.Comment: Data descriptor for the Human Mobility Prediction Challenge (HuMob
Challenge) 202
Dependence of alkyl-substituent length for bulk heterojunction solar cells utilizing 1,4,8,11,15,18,22,25-octaalkylphthalocyanine
Tetsuro Hori, Yasuo Miyake, Tetsuya Masuda, Takeshi Hayashi, Kaoru Fukumura, Hiroyuki Yoshida, Akihiko Fujii, Masanori Ozaki, and Yo Shimizu "Dependence of alkyl-substituent length for bulk heterojunction solar cells utilizing 1,4,8,11,15,18,22,25-octaalkylphthalocyanine," Journal of Photonics for Energy 2(1), 021004 (2 March 2012). DOI: https://doi.org/10.1117/1.JPE.2.02100
Effects of multiple pairs on visibility measurements of entangled photons generated by spontaneous parametric processes
Entangled photon-pair sources based on spontaneous parametric processes are
widely used in photonic quantum information experiments. In this paper, we
clarify the relationship between average photon-pair number and the visibility
of two-photon interference (TPI) using those entanglement sources. We consider
sources that generate distinguishable and indistinguishable entangled photon
pairs, assuming coincidence measurements that use threshold detectors. We
present formulas for the TPI visibility of a polarization entanglement that
take account of all the high-order multi-pair emission events. Moreover, we
show that the formulas can be approximated with simple functions of the average
pair number when the photon collection efficiency is small. As a result, we
reveal that an indistinguishable entangled pair provides better visibility than
a distinguishable one
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