258 research outputs found
Phase Current Measurement Method of Dual Inverter-Motor Drive System Using a Single DC Link Current Sensor
In recent years, electric propulsion systems have become widely, used and these systems have strict limits in volume and weight. Therefore, it is necessary to reduce the weight of the inverter-motor drive system. In a typical n inverter-motor drive system, at least 2n phase current sensors are required. In order to reduce the number of phase current sensors, this paper proposes a method for measuring phase current using n DC link current sensors in a 2n inverter-motor drive system. Two phase currents per inverter-motor system are measured during one period of the switching frequency using the pulse width modulation (PWM) shift method. However, since the measured phase current contains an error component in the average current, the error component was compensated for in order to obtain a current similar to the actual phase current by using the slope and dwell time of the phase current. The effectiveness of the proposed method is verified through experiments
Switching Magnetism and Superconductivity with Spin-Polarized Current in Iron-Based Superconductor
We have explored a new mechanism for switching magnetism and
superconductivity in a magnetically frustrated iron-based superconductor using
spin-polarized scanning tunneling microscopy (SPSTM). Our SPSTM study on single
crystal SrVOFeAs shows that a spin-polarized tunneling current can
switch the Fe-layer magnetism into a non-trivial (22) order, not
achievable by thermal excitation with unpolarized current. Our tunneling
spectroscopy study shows that the induced (22) order has
characteristics of plaquette antiferromagnetic order in Fe layer and strongly
suppressed superconductivity. Also, thermal agitation beyond the bulk Fe spin
ordering temperature erases the state. These results suggest a new
possibility of switching local superconductivity by changing the symmetry of
magnetic order with spin-polarized and unpolarized tunneling currents in
iron-based superconductors.Comment: 33 pages, 16 figure
Universality and diversity of folding mechanics for three-helix bundle proteins
In this study we evaluate, at full atomic detail, the folding processes of
two small helical proteins, the B domain of protein A and the Villin headpiece.
Folding kinetics are studied by performing a large number of ab initio Monte
Carlo folding simulations using a single transferable all-atom potential. Using
these trajectories, we examine the relaxation behavior, secondary structure
formation, and transition-state ensembles (TSEs) of the two proteins and
compare our results with experimental data and previous computational studies.
To obtain a detailed structural information on the folding dynamics viewed as
an ensemble process, we perform a clustering analysis procedure based on graph
theory. Moreover, rigorous pfold analysis is used to obtain representative
samples of the TSEs and a good quantitative agreement between experimental and
simulated Fi-values is obtained for protein A. Fi-values for Villin are also
obtained and left as predictions to be tested by future experiments. Our
analysis shows that two-helix hairpin is a common partially stable structural
motif that gets formed prior to entering the TSE in the studied proteins. These
results together with our earlier study of Engrailed Homeodomain and recent
experimental studies provide a comprehensive, atomic-level picture of folding
mechanics of three-helix bundle proteins.Comment: PNAS, in press, revised versio
Congenital Cerebellar Mixed Germ Cell Tumor Presenting with Hemorrhage in a Newborn
We report here on a neonate with congenital cerebellar mixed germ cell tumor, and this initially presented as cerebellar hemorrhage. Postnatal cranial ultrasonography revealed an echogenic cerebellar mass that exhibited the signal characteristics of hemorrhage rather than tumor on MR images. The short-term follow-up images also suggested a resolving cerebellar hemorrhage. One month later, the neonate developed vomiting. A second set of MR images demonstrated an enlarged mass that exhibited changed signal intensity at the same site, which suggested a neoplasm. Histological examination after the surgical resection revealed a mixed germ cell tumor
Association between Participation in a Rehabilitation Program and 1-Year Survival in Patients Requiring Prolonged Mechanical Ventilation
Background The present study evaluated the association between participation in a rehabilitation program during a hospital stay and 1-year survival of patients requiring at least 21 days of mechanical ventilation (prolonged mechanical ventilation [PMV]) with various respiratory diseases as their main diagnoses that led to mechanical ventilation. Methods Retrospective data of 105 patients (71.4% male, mean age 70.1±11.3 years) who received PMV in the past 5 years were analyzed. Rehabilitation included physiotherapy, physical rehabilitation, and dysphagia treatment program that was individually provided by physiatrists. Results The main diagnosis leading to mechanical ventilation was pneumonia (n=101, 96.2%) and the 1-year survival rate was 33.3% (n=35). One-year survivors had lower Acute Physiology and Chronic Health Evaluation (APACHE) II score (20.2±5.8 vs. 24.2±7.5, p=0.006) and Sequential Organ Failure Assessment score (6.7±5.6 vs. 8.5±2.7, p=0.001) on the day of intubation than non-survivors. More survivors participated in a rehabilitation program during their hospital stays (88.6% vs. 57.1%, p=0.001). The rehabilitation program was an independent factor for 1-year survival based on the Cox proportional hazard model (hazard ratio, 3.513; 95% confidence interval, 1.785 to 6.930; p<0.001) in patients with APACHE II scores ≤23 (a cutoff value based on Youden’s index). Conclusion Our study showed that participation in a rehabilitation program during hospital stay was associated with an improvement of 1-year survival of PMV patients who had less severe illness on the day of intubation
The genus Arthrinium (Ascomycota, Sordariomycetes, Apiosporaceae) from marine habitats from Korea, with eight new species
Species of Arthrinium are well-known plant pathogens, endophytes, or saprobes found in various terrestrial habitats. Although several species have been isolated from marine environments and their remarkable biological activities have been reported, marine Arthrinium species remain poorly understood. In this study, the diversity of this group was evaluated based on material from Korea, using morphological characterization and molecular analyses with the internal transcribed spacer (ITS) region, β-tubulin (TUB), and translation elongation factor 1-alpha (TEF). A total of 41 Arthrinium strains were isolated from eight coastal sites which represented 14 species. Eight of these are described as new to science with detailed descriptions.This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (NRF-2017R1A2B4002071). Additional funding was provided by the project for the survey and excavation of Korean indigenous species of the National Institute of Biological Resources [NIBR201902113] under the Ministry of Environment, Republic of Korea, and the Marine Biotechnology Program of the Korea Institute of Marine Science and Technology Promotion (KIMST), funded by the Ministry of Oceans and Fisheries (MOF) (No. 20170431 & No. 20170325)
Insulin Resistance as a Risk Factor for Gallbladder Stone Formation in Korean Postmenopausal Women
Correction to: The genus Arthrinium (Ascomycota, Sordariomycetes, Apiosporaceae) from marine habitats from Korea, with eight new species
Correlation of Fe-Based Superconductivity and Electron-Phonon Coupling in an FeAs/Oxide Heterostructure
Interfacial phonons between iron-based superconductors (FeSCs) and perovskite substrates have received considerable attention due to the possibility of enhancing preexisting superconductivity. Using scanning tunneling spectroscopy, we studied the correlation between superconductivity and e−ph interaction with interfacial phonons in an iron-based superconductor Sr2VO3FeAs (Tc≈33 K) made of alternating FeSC and oxide layers. The quasiparticle interference measurement over regions with systematically different average superconducting gaps due to the e−ph coupling locally modulated by O vacancies in the VO2 layer, and supporting self-consistent momentum-dependent Eliashberg calculations provide a unique real-space evidence of the forward-scattering interfacial phonon contribution to the total superconducting pairing. © 2017 American Physical Society6
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