472 research outputs found

    Directly pumped 10  GHz microcomb modules from low-power diode lasers

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    Soliton microcombs offer the prospect of advanced optical metrology and timing systems in compact form factors. In these applications, the pumping of microcombs directly from a semiconductor laser without amplification or triggering components is desirable to reduce system power and to simplify system design. At the same time, low-repetition-rate microcombs are required in many comb applications as an interface to detectors and electronics, but their increased mode volume makes them challenging to pump at low power. Here 10 GHz repetition rate soliton microcombs are directly pumped by low-power (<20  mW) diode lasers. High-Q silica microresonators are used for this low-power operation and are packaged into fiber-connectorized modules that feature temperature control for improved long-term frequency stability

    Assessing Optimal Set of Implemental Physical Parameterization Schemes in a Multi-Physics Land Surface Model Using Genetic Algorithm

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    Optimization of land surface models has been challenging due to the model complexity and uncertainty. In this study, we performed scheme-based model optimizations by designing a framework for coupling the micro-genetic algorithm (micro-GA) and the Noah land surface model with multiple physics options (Noah-MP). Micro-GA controls the scheme selections among eight different land surface parameterization categories, each containing 2–4 schemes, in Noah-MP in order to extract the optimal scheme combination that achieves the best skill score. This coupling framework was successfully applied to the optimizations of evapotranspiration and runoff simulations in terms of surface water balance over the Han River basin in Korea, showing outstanding speeds in searching for the optimal scheme combination. Taking advantage of the natural selection mechanism in micro-GA, we explored the model sensitivity to scheme selections and the scheme interrelationship during the micro-GA evolution process. This information is helpful for better understanding physical parameterizations and hence it is expected to be effectively used for further optimizations with uncertain parameters in a specific set of schemes

    Criterion for transformation of transverse domain wall to vortex or antivortex wall in soft magnetic thin-film nanostripes

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    We report on the criterion for the dynamic transformation of the internal structure of moving domain walls (DWs) in soft magnetic thin-film nanostripes above the Walker threshold field, Hw. In order for the process of transformation from transverse wall (TW) to vortex wall (VW) or antivortex wall (AVW) occurs, the edge-soliton core of the TW-type DW should grow sufficiently to the full width at half maximum of the out-of-plane magnetizations of the core area of the stabilized vortex (or antivortex) by moving inward along the transverse (width) direction. Upon completion of the nucleation of the vortex (antivortex) core, the VW (AVW) is stabilized, and then its core accompanies the gyrotropic motion in a potential well (hill) of a given nanostripe. Field strengths exceeding the Hw, which is the onset field of DW velocity breakdown, are not sufficient but necessary conditions for dynamic DW transformation

    Microstructure evolution and thermal durability with coating thickness in APS thermal barrier coatings

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    The effects of the coating thickness on the delamination or fracture behavior of thermal barrier coatings (TBCs) were investigated through the cyclic furnace thermal fatigue (CFTF) and thermal shock (TS) tests. The TBCs were prepared using a NiCrAlY bond coat and an yttria-stabilized zirconia top coat, which were formed using the air plasma spray (APS) process. The thicknesses of the top coat were 200 and 400 μm, and those of the bond coat were 100 and 200 μm. TBC samples with a thickness ratio of 2:1 in the top and bond coats were employed in the CFTF and TS tests. After CFTF for 1429 cycles, the interface microstructure of the relatively thick TBC was in a sound condition without any cracking or delamination; however, the relatively thin TBC was delaminated near the interface between the top and bond coats after 721 cycles. In the TS, the TBCs were fully delaminated (> 50%) after 140 and 194 cycles for thicknesses of 200 and 400 μm in the top coat, respectively. These observations allow us to control the thickness of TBC prepared using the APS process, and the thicker TBC is more efficient in improving thermal durability in the cyclic thermal exposure and thermal shock environments

    Zee Model Confronts SNO Data

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    We reexamine the solution of the minimal Zee model by comparing with the data of the SNO experiment, and conclude that the model is strongly disfavored but not yet excluded by the observations. Two extensions of the Zee model are briefly discussed both of which introduce additional freedom and can accommodate the data.Comment: 16 pages LaTeX including 7 figure

    Directly pumped 10  GHz microcomb modules from low-power diode lasers

    Get PDF
    Soliton microcombs offer the prospect of advanced optical metrology and timing systems in compact form factors. In these applications, the pumping of microcombs directly from a semiconductor laser without amplification or triggering components is desirable to reduce system power and to simplify system design. At the same time, low-repetition-rate microcombs are required in many comb applications as an interface to detectors and electronics, but their increased mode volume makes them challenging to pump at low power. Here 10 GHz repetition rate soliton microcombs are directly pumped by low-power (<20  mW) diode lasers. High-Q silica microresonators are used for this low-power operation and are packaged into fiber-connectorized modules that feature temperature control for improved long-term frequency stability

    Visual outcomes and safety after bilateral implantation of a trifocal presbyopia correcting intraocular lens in a Korean population: a prospective single-arm study

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    Abstract Background To investigate the 3-month postoperative performance and safety after implantation of a trifocal intraocular lens (IOL) in a Korean population. Methods This was a clinical, prospective, multicenter, single-arm study. Forty-four subjects (88 eyes) with bilateral cataract with expected postoperative corneal astigmatism of < 1.00 diopter (D) and no ocular disease or eye condition underwent bilateral implantation of the AcrySof IQ® PanOptix IOL (TFNT00). Postoperative examination at 3 months included binocular defocus curve; binocular best corrected distance visual acuity (BCDVA); monocular/binocular uncorrected VA (UCVA) at distance (4 m), intermediate (60 cm), and near (40 cm); contrast sensitivity under photopic conditions with/without glare; and subjective outcomes, including satisfaction and spectacle independence. Results Binocular defocus curve at 3 months after bilateral implantation showed VA of 0.1 logMAR or better from + 0.5 D through − 2.5 D. Binocular BCDVA mean ± SD at 4 m was − 0.05 ± 0.07 logMAR. Binocular and monocular UCVA was 0.03 ± 0.1 and 0.08 ± 0.12 logMAR (4 m), − 0.00 ± 0.11 and 0.05 ± 0.13 logMAR (60 cm), and 0.03 ± 0.12 and 0.09 ± 0.13 logMAR (40 cm), respectively. Contrast sensitivity with glare was 1.67 ± 0.13, 1.91 ± 0.17, 1.54 ± 0.21, and 1.14 ± 0.20 log units at 3, 6, 12, and 18 cycles/degree, respectively. At near and intermediate distances, 84 and 77% of subjects reported good/excellent satisfaction, and 84 and 91% of subjects reported spectacle independence, respectively. Conclusions In a Korean population, visual performance of the trifocal TFNT00 IOL 3 months postoperatively was < 0.1 logMAR for binocular UCVA at all distances, with high subject satisfaction and spectacle independence. Trial registration www.ClinicalTrials.gov ( NCT03268746 ). Registered August 31, 2017

    Implant-supported fixed and removable prostheses in the fibular mandible

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    Abstract Background To restore the health-related quality of life (HRQoL) of patients who underwent jaw resection and reconstruction surgery, dental rehabilitation is an essential procedure and also one of the most challenging for oral and maxillofacial surgeons. Even though recent studies have reported the possibility and reliability of dental implant rehabilitation with the fibula free flap (FFF), clinical reports of long-term follow-up cases are scarce. We herein reported seven cases of FFF reconstruction and implant rehabilitation. We also discussed implant planning strategy and surgical techniques. Methods From 2012 to 2019, seven patients were treated with FFF reconstructive jaw surgery combined with dental implant installation and fabrication of implant-supported prostheses at Seoul National University Dental Hospital, Seoul, Korea. Patient characteristics and FFF treatment results were collected. Records of dental implants were analyzed clinically and radiologically. Results Among the seven patients in this report, there were three males and four females, with an average age of 54.4 years. A total of 39 implants were placed in the fibular bone. The mean follow-up period after implant installation was 24 months. Five implants failed and were removed 3 months after installation. The implant success rate was 87.2%. Marginal bone loss at 12 months after loading was 0.23 ± 0.18 mm on the mesial side and 0.25 ± 0.26 mm on the distal side. Conclusion With the challenges present in FFF-reconstructed patients, an implant-supported prosthesis is a reliable option for stable and functional oral rehabilitation. The implant-supported prosthesis on the FFF has great results regarding restoration of function (mastication, swallowing, and speaking), appearance, and overall HRQoL. Collaboration between surgeons and prosthodontists is essential for a satisfying outcome

    Abortive Lytic Reactivation of KSHV in CBF1/CSL Deficient Human B Cell Lines

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    Since Kaposi's sarcoma associated herpesvirus (KSHV) establishes a persistent infection in human B cells, B cells are a critical compartment for viral pathogenesis. RTA, the replication and transcription activator of KSHV, can either directly bind to DNA or use cellular DNA binding factors including CBF1/CSL as DNA adaptors. In addition, the viral factors LANA1 and vIRF4 are known to bind to CBF1/CSL and modulate RTA activity. To analyze the contribution of CBF1/CSL to reactivation in human B cells, we have successfully infected DG75 and DG75 CBF1/CSL knock-out cell lines with recombinant KSHV.219 and selected for viral maintenance by selective medium. Both lines maintained the virus irrespective of their CBF1/CSL status. Viral reactivation could be initiated in both B cell lines but viral genome replication was attenuated in CBF1/CSL deficient lines, which also failed to produce detectable levels of infectious virus. Induction of immediate early, early and late viral genes was impaired in CBF1/CSL deficient cells at multiple stages of the reactivation process but could be restored to wild-type levels by reintroduction of CBF1/CSL. To identify additional viral RTA target genes, which are directly controlled by CBF1/CSL, we analyzed promoters of a selected subset of viral genes. We show that the induction of the late viral genes ORF29a and ORF65 by RTA is strongly enhanced by CBF1/CSL. Orthologs of ORF29a in other herpesviruses are part of the terminase complex required for viral packaging. ORF65 encodes the small capsid protein essential for capsid shell assembly. Our study demonstrates for the first time that in human B cells viral replication can be initiated in the absence of CBF1/CSL but the reactivation process is severely attenuated at all stages and does not lead to virion production. Thus, CBF1/CSL acts as a global hub which is used by the virus to coordinate the lytic cascade

    Polarization characteristics of phase retardation defect mode lasing in polymeric cholesteric liquid crystals

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    We have studied the lasing characteristics of a dye-doped nematic layer sandwiched by two polymeric cholesteric liquid crystal (CLC) films as photonic band gap (PBG) materials. The nematic layer acts as a defect layer, the anisotropy of which brings about the following remarkable optical characteristics: (1) reflectance in the PBG region exceeds 50% due to the retardation effect, being unpredictable from a single CLC film; (2) efficient lasing occurs either at the defect mode wavelength or at the photonic band edge; and (3) the lasing emission due to both the defect mode and the photonic band edge mode contains both right- and left-circular polarizations, while the lasing emission from a dye-doped single CLC layer with a left-handed helix is left-circularly polarized.open2
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