840 research outputs found
Simulation and Experiment Analysis of Driveshaft
A driveshaft is a small spring coil less than 1mm in diameter, composed of several stainless-steel wire filaments. In intervention, the driveshaft is used to transmit force and motion to the inside body through the existing micro channels (such as arteries, veins, and gastrointestinal tract). The performance of the driveshaft determines the efficiency, stability, and accuracy of force and motion transitions, the ability to pass through tortuous microchannels, and the damage to healthy tissues. To determine the influence of fabrication parameters (filament, wire diameter, and outer diameter) on the mechanical properties (such as bending stiffness and natural frequency) of the driveshaft, a simulation was established in ABAQUS to calculate the deformation displacement under 0.0098N and first-order natural frequency. Then, the bending stiffness is calculated. The results show that the bending stiffness and the first-order natural frequency of the driveshaft increase with the increase of the filament number and wire diameter, and with the outer diameter of the driveshaft increases, the bending stiffness increases, while the first-order natural frequency decreases. Finally, the simulation model is verified by measuring the deformation displacement in the experiment. This study provides a methodology for designing and selecting the driveshaft in Interventional therapy
Microstructure and Mechanical Properties of a-CN x Films Prepared by Bias Voltage Assisted PLD with Carbon Nitride Target
International audienceAmorphous carbon nitride (a-CN x) films were deposited on silicon substrates using pulsed laser deposition technique (PLD) with a carbon nitride target and a negative bias voltage up to -120 V. The microstructure, chemical composition, bonding configuration and mechanical properties of the films were characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, nanoindentation and ball-on-disc abrasion test. The results show that the negative bias voltage promotes the formation of sp 3 hybridization bonding and leads to a great improvement of nitrogen content (up to 38 at.%) in the films. With an increasing bias voltage from -40 V to -120 V, the nitrogen content and the fraction of sp 3 hybridization bonding Corresponding author
Secure Inter-domain Routing and Forwarding via Verifiable Forwarding Commitments
The Internet inter-domain routing system is vulnerable. On the control plane,
the de facto Border Gateway Protocol (BGP) does not have built-in mechanisms to
authenticate routing announcements, so an adversary can announce virtually
arbitrary paths to hijack network traffic; on the data plane, it is difficult
to ensure that actual forwarding path complies with the control plane
decisions. The community has proposed significant research to secure the
routing system. Yet, existing secure BGP protocols (e.g., BGPsec) are not
incrementally deployable, and existing path authorization protocols are not
compatible with the current Internet routing infrastructure. In this paper, we
propose FC-BGP, the first secure Internet inter-domain routing system that can
simultaneously authenticate BGP announcements and validate data plane
forwarding in an efficient and incrementally-deployable manner. FC-BGP is built
upon a novel primitive, name Forwarding Commitment, to certify an AS's routing
intent on its directly connected hops. We analyze the security benefits of
FC-BGP in the Internet at different deployment rates. Further, we implement a
prototype of FC-BGP and extensively evaluate it over a large-scale overlay
network with 100 virtual machines deployed globally. The results demonstrate
that FC-BGP saves roughly 55% of the overhead required to validate BGP
announcements compared with BGPsec, and meanwhile FC-BGP introduces a small
overhead for building a globally-consistent view on the desirable forwarding
paths.Comment: 16 pages, 17 figure
Metalorganic chemical vapor deposition growth of InAs/GaSb type II superlattices with controllable AsxSb1-x interfaces
InAs/GaSb type II superlattices were grown on (100) GaSb substrates by metalorganic chemical vapor deposition (MOCVD). A plane of mixed As and Sb atoms connecting the InAs and GaSb layers was introduced to compensate the tensile strain created by the InAs layer in the SL. Characterizations of the samples by atomic force microscopy and high-resolution X-ray diffraction demonstrate flat surface morphology and good crystalline quality. The lattice mismatch of approximately 0.18% between the SL and GaSb substrate is small compared to the MOCVD-grown supperlattice samples reported to date in the literature. Considerable optical absorption in 2- to 8-μm infrared region has been realized
Optoelectronic properties and ultrafast carrier dynamics of copper iodide thin films
As a promising high mobility p-type wide bandgap semiconductor, copper iodide has received increasing attention in recent years. However, the defect physics/evolution are still controversial, and particularly the ultrafast carrier and exciton dynamics in copper iodide has rarely been investigated. Here, we study these fundamental properties for copper iodide thin films by a synergistic approach employing a combination of analytical techniques. Steady-state photoluminescence spectra reveal that the emission at ~420 nm arises from the recombination of electrons with neutral copper vacancies. The photogenerated carrier density dependent ultrafast physical processes are elucidated with using the femtosecond transient absorption spectroscopy. Both the effects of hot-phonon bottleneck and the Auger heating significantly slow down the cooling rate of hot-carriers in the case of high excitation density. The effect of defects on the carrier recombination and the two-photon induced ultrafast carrier dynamics are also investigated. These findings are crucial to the optoelectronic applications of copper iodide
High remission and low relapse with prolonged intensive DMARD therapy in rheumatoid arthritis (PRINT): A multicenter randomized clinical trial
Objectives: To determine whether prolonged intensive disease-modifying antirheumatic drug (DMARD) treatment (PRINT) leads to high remission and low relapse rates in patients with severe rheumatoid arthritis (RA).
Methods: In this multicenter, randomized and parallel treatment trial, 346 patients with active RA (disease activity score (28 joints) [DAS28] (erythrocyte sedimentation rate [ESR]) > 5.1) were enrolled from 9 centers. In phase 1, patients received intensive treatment with methotrexate, leflunomide, and hydroxychloroquine, up to 36 weeks, until remission (DAS28 ≤ 2.6) or a low disease activity (2.6 < DAS28 ≤ 3.2) was achieved. In phase 2, patients achieving remission or low disease activity were followed up with randomization to 1 of 2 step-down protocols: leflunomide plus hydroxychloroquine combination or leflunomide monotherapy. The primary endpoints were good European League Against Rheumatism (EULAR) response (DAS28 (ESR) < 3.2 and a decrease of DAS28 by at least 1.2) during the intensive treatment and the disease state retention rate during step-down maintenance treatment. Predictors of a good EULAR response in the intensive treatment period and disease flare in the maintenance period were sought.
Results: A good EULAR response was achieved in 18.7%, 36.9%, and 54.1% of patients at 12, 24, and 36 weeks, respectively. By 36 weeks, 75.4% of patients achieved good and moderate EULAR responses. Compared with those achieving low disease activity and a high health assessment questionnaire (HAQ > 0.5), patients achieving remission (DAS28 ≤ 2.6) and low HAQ (≤ 0.5) had a significantly higher retention rate when tapering the DMARDs treatment (P = 0.046 and P = 0.01, respectively). There was no advantage on tapering to combination rather than monotherapy.
Conclusions: Remission was achieved in a proportion of patients with RA receiving prolonged intensive DMARD therapy. Low disease activity at the start of disease taper leads to less subsequent flares. Leflunomide is a good maintenance treatment as single treatment
Immune Checkpoint Inhibitors-Related Thyroid Dysfunction: Epidemiology, Clinical Presentation, Possible Pathogenesis, and Management
Immune checkpoint inhibitors (ICIs) are a group of drugs employed in the treatment of various types of malignant tumors and improve the therapeutic effect. ICIs blocks negative co-stimulatory molecules, such as programmed cell death gene-1 (PD-1) and its ligand (PD-L1) and cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), reactivating the recognition and killing effect of the immune system on tumors. However, the reactivation of the immune system can also lead to the death of normal organs, tissues, and cells, eventually leading to immune-related adverse events (IRAEs). IRAEs involve various organs and tissues and also cause thyroid dysfunction. This article reviews the epidemiology, clinical manifestations, possible pathogenesis, and management of ICIs-related thyroid dysfunction
Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay
The Daya Bay experiment has observed correlations between reactor core fuel
evolution and changes in the reactor antineutrino flux and energy spectrum.
Four antineutrino detectors in two experimental halls were used to identify 2.2
million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles
for each of six 2.9 GW reactor cores at the Daya Bay and Ling
Ao nuclear power plants. Using detector data spanning effective Pu
fission fractions, , from 0.25 to 0.35, Daya Bay measures an average
IBD yield, , of
cm/fission and a fuel-dependent variation in the IBD yield,
, of cm/fission.
This observation rejects the hypothesis of a constant antineutrino flux as a
function of the Pu fission fraction at 10 standard deviations. The
variation in IBD yield was found to be energy-dependent, rejecting the
hypothesis of a constant antineutrino energy spectrum at 5.1 standard
deviations. While measurements of the evolution in the IBD spectrum show
general agreement with predictions from recent reactor models, the measured
evolution in total IBD yield disagrees with recent predictions at 3.1.
This discrepancy indicates that an overall deficit in measured flux with
respect to predictions does not result from equal fractional deficits from the
primary fission isotopes U, Pu, U, and Pu.
Based on measured IBD yield variations, yields of and cm/fission have been determined for the two
dominant fission parent isotopes U and Pu. A 7.8% discrepancy
between the observed and predicted U yield suggests that this isotope
may be the primary contributor to the reactor antineutrino anomaly.Comment: 7 pages, 5 figure
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