90 research outputs found
Phase-sensitive Manipulations of Squeezed Vacuum Field in an Optical Parametric Amplifier inside an Optical Cavity
Squeezed vacuum field can be amplified or deamplified when it is injected, as
the signal beam, into a phase-sensitive optical parametric amplifier (OPA)
inside an optical cavity. The spectral features of the reflected quantized
signal field are controlled by the relative phase between the injected squeezed
vacuum field and the pump field for the OPA. The experimental results
demonstrate coherent phenomena of OPA in the quantum regime, and show
phase-sensitive manipulations of quantum fluctuations for quantum information
processing.Comment: 4 pages, 3 figures, appear in Phys. Rev. Let
A Comprehensive Study of Governance Issues in Decentralized Finance Applications
Decentralized Finance (DeFi) is a prominent application of smart contracts,
representing a novel financial paradigm in contrast to centralized finance.
While DeFi applications are rapidly emerging on mainstream blockchain
platforms, their quality varies greatly, presenting numerous challenges,
particularly in terms of their governance mechanisms. In this paper, we present
a comprehensive study of governance issues in DeFi applications. Drawing upon
insights from industry reports and academic research articles, we develop a
taxonomy to categorize these governance issues. We collect and build a dataset
of 4,446 audit reports from 17 Web3 security companies, categorizing their
governance issues according to our constructed taxonomy. We conducted a
thorough analysis of governance issues and identified vulnerabilities in
governance design and implementation, e.g., voting sybil attack and proposal
front-running. Our findings highlight a significant observation: the disparity
between smart contract code and DeFi whitepapers plays a central role in these
governance issues. As an initial step to address the challenges of
code-whitepaper consistency checks for DeFi applications, we built a
machine-learning-based prototype, and validated its performance on eight widely
used DeFi projects, achieving a 56.14% F1 score and a 80% recall. Our study
culminates in providing several key practical implications for various DeFi
stakeholders, including developers, users, researchers, and regulators, aiming
to deepen the understanding of DeFi governance issues and contribute to the
robust growth of DeFi systems
FAST: Improving Controllability for Text Generation with Feedback Aware Self-Training
Controllable text generation systems often leverage control codes to direct
various properties of the output like style and length. Inspired by recent work
on causal inference for NLP, this paper reveals a previously overlooked flaw in
these control code-based conditional text generation algorithms. Spurious
correlations in the training data can lead models to incorrectly rely on parts
of the input other than the control code for attribute selection, significantly
undermining downstream generation quality and controllability. We demonstrate
the severity of this issue with a series of case studies and then propose two
simple techniques to reduce these correlations in training sets. The first
technique is based on resampling the data according to an example's propensity
towards each linguistic attribute (IPS). The second produces multiple
counterfactual versions of each example and then uses an additional feedback
mechanism to remove noisy examples (feedback aware self-training, FAST). We
evaluate on 3 tasks -- news headline, meta review, and search ads generation --
and demonstrate that FAST can significantly improve the controllability and
language quality of generated outputs when compared to state-of-the-art
controllable text generation approaches
Electromagnetically-Induced-Transparency-Like Effect in the Degenerate Triple-Resonant Optical Parametric Amplifier
We investigate experimentally the absorptive and dispersive properties of
triple-resonant optical parametric amplifier OPA for the degenerate subharmonic
field. In the experiment, the subharmonic field is utilized as the probe field
and the harmonic wave as the pump field. We demonstrate that EIT-like effect
can be simulated in the triple-resonant OPA when the cavity line-width for the
harmonic wave is narrower than that for the subharmonic field. However, this
phenomenon can not be observed in a double-resonant OPA. The narrow
transparency window appears in the reflected field. Especially, in the measured
dispersive spectra of triple-resonant OPA, a very steep variation of the
dispersive profile of the subharmonic field is observed, which can result in a
slow light as that observed in atomic EIT medium.Comment: 10 pages, 4 figures, appear in Opt. Let
Characteristics and metabolic potential of biliary microbiota in patients with giant common bile duct stones
BackgroundEndoscopic retrograde cholangiopancreatography (ERCP) is an effective minimally invasive operation for the management of choledocholithiasis, while successful extraction is hampered by large diameter of stones. Emerging studies have revealed the close correlation between biliary microbiota and common bile duct stones (CBDS). In this study, we aimed to investigate the community characteristics and metabolic functions of biliary microbiota in patients with giant CBDS.MethodsEligible patients were prospectively enrolled in this study in First Affiliated Hospital of Soochow University from February 2022 to October 2022. Bile samples were collected through ERCP. The microbiota was analyzed using 16S rRNA sequencing. Metabolic functions were predicted by PICRUSTs 2.0 calculation based on MetaCyc database. Bile acids were tested and identified using ultra performance liquid chromatography-tandem mass spectrometry.ResultsA total of 26 patients were successfully included into final analysis, 8 in giant stone (GS) group and 18 in control group. Distinct biliary microbial composition was identified in patients with giant CBDS, with a significantly higher abundance of Firmicutes at phylum level. The unique composition at genus level mainly consisted of Enterococcus, Citrobacter, Lactobacillus, Pyramidobacter, Bifidobacterium and Shewanella. Pyramidobacter was exclusively found in GS group, along with the absence of Robinsoniella and Coprococcus. The contents of free bile acids were significantly higher in GS group, including cholic acid (98.39μmol/mL vs. 26.15μmol/mL, p=0.035), chenodesoxycholic acid (54.69μmol/mL vs. 5.86μmol/mL, p=0.022) and ursodeoxycholic acid (2.70μmol/mL vs. 0.17μmol/mL, p=0.047). Decreasing tendency of conjugated bile acids were also observed. Metabolic pathways concerning cholelithiasis were abundant in GS group, including geranylgeranyl diphosphate biosynthesis, gluconeogenesis, glycolysis and L-methionine biosynthesis.ConclusionsThis study demonstrated the community structure and metabolic potential of biliary microbiota in patients with giant CBDS. The unique biliary microbial composition holds valuable predictive potential for clinical conditions. These findings provide new insights into the etiology of giant CBDS from the perspective of biliary microbiota
Physical Human-Robot Interaction of a Robotic Exoskeleton By Admittance Control
In this paper, physical human-robot interaction (pHRI) approach is presented for the developed robotic exoskeleton using admittance control to deal with human subject's intention as well as the unknown inertia masses and moments in the robotic dynamics. Human subject's intention is represented by the reference trajectory when the robotic exoskeleton is complying with the external interaction force. Online estimation of the stiffness is employed to deal with the variable impedance property of the robotic exoskeleton. Admittance control is firstly presented based on the measured force in order to generate a reference trajectory in interaction tasks. Then adaptive control is proposed to deal with the uncertain robotic dynamics and a stability criterion can be obtained. Bounded errors are shown in the motion tracking while the robustness of the variable stiffness control is guaranteed. The experimental results indicate that the proposed control enables the human subjects to execute an admittance control task on the exoskeleton robot effectively
Measurement of distal intramural spread and the optimal distal resection by naked eyes after neoadjuvant radiation for rectal cancers
BACKGROUND: The safe distance between the intraoperative resection line and the visible margin of the distal rectal tumor after preoperative radiotherapy is unclear. We aimed to investigate the furthest tumor intramural spread distance in fresh tissue to determine a safe distal intraoperative resection margin length. METHODS: Twenty rectal cancer specimens were collected after preoperative radiotherapy. Tumor intramural spread distances were defined as the distance between the tumor’s visible and microscopic margins. Visible tumor margins in fresh specimens were identified during the operation and were labeled with 5 - 0 sutures under the naked eye at the distal 5, 6, and 7 o’clock directions of visible margins immediately after removal of the tumor. After fixation with formalin, the sutures were injected with nanocarbon particles. Longitudinal tissues were collected along three labels and stained with hematoxylin and eosin. The spread distance after formalin fixation was measured between the furthest intramural spread of tumor cells and the nanocarbon under a microscope. A positive intramural spread distance indicated that the furthest tumor cell was distal to the nanocarbon, and a negative value indicated that the tumor cell was proximal to the nanocarbon. The tumor intramural spread distance in fresh tissue during the operation was 1.75 times the tumor intramural spread distance after formalin fixation according to the literature. RESULTS: At the distal 5, 6, and 7 o’clock direction, seven (35%), five (25%), and six (30%) patients, respectively, had distal tumor cell intramural spread distance > 0 mm. The mean and 95% confidence interval of tumor cell intramural spread distance in fresh tissue during operation was − 0.3 (95%CI − 4.0 ~ 3.4) mm, − 0.9 (95%CI − 3.4 ~ 1.7) mm, and − 0.4 (95%CI − 3.5 ~ 2.8) mm, respectively. The maximal intraoperative intramural spread distances in fresh tissue were 8.8, 7, and 7 mm, respectively. CONCLUSIONS: The intraoperative distance between the distal resection line and the visible margin of the rectal tumor after radiotherapy should not be less than 1 cm to ensure oncological safety
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