491 research outputs found
Measurement of Galactic Cosmic Ray Proton and Helium Spectra During the 1987 Solar Minimum.
The differential cosmic ray proton and helium spectra have been measured during the 1987 solar minimum using a balloon-borne superconducting magnetic spectrometer launched from Prince Albert, Canada. The changing geomagnetic cutoff along the balloon trajectory was observed in the low energy proton data to be about 25% below the nominal calculated values. The measured particle fluxes were approximately equal to the highest fluxes observed at the previous solar minimum in 1977. Above 10 GV the observed spectra are represented by a power law in rigidity with spectral indices of 2.74 0.02 for protons and 2.68 0.03 for helium. The measurements above 200 MeV/nucleon are consistent with rigidity power law interstellar spectra modulated with the solar modulation parameter = 500 MV. The energy dependence of the proton to helium ratio is consistent with rigidity power law injection spectra and rigidity-dependent propagation without re-acceleration
Spectrum of Galactic Cosmic Rays Accelerated in Supernova Remnants
The spectra of high-energy protons and nuclei accelerated by supernova
remnant shocks are calculated taking into account magnetic field amplification
and Alfvenic drift both upstream and downstream of the shock for different
types of supernova remnants during their evolution. The maximum energy of
accelerated particles may reach eV for Fe ions in Type IIb
SNRs. The calculated energy spectrum of cosmic rays after propagation through
the Galaxy is in good agreement with the spectrum measured at the Earth.Comment: 9 pages, 3 figures, accepted to Ap
Pivotal-based inference for a Pareto distribution under the adaptive progressive Type-II censoring scheme
This paper proposes an inference approach based on a pivotal quantity under the adaptive progressive Type-II censoring scheme. To exemplify the proposed methodology, an extensively employed distribution, a Pareto distribution, is utilized. This distribution has limitations in estimating confidence intervals for unknown parameters from classical methods such as the maximum likelihood and bootstrap methods. For example, in the maximum likelihood method, the asymptotic variance-covariance matrix does not always exist. In addition, both classical methods can yield confidence intervals that do not satisfy nominal levels when a sample size is not large enough. Our approach resolves these limitations by allowing us to construct exact intervals for unknown parameters with computational simplicity. Aside from this, the proposed approach leads to closed-form estimators with properties such as unbiasedness and consistency. To verify the validity of the proposed methodology, two approaches, a Monte Carlo simulation and a real-world data analysis, are conducted. The simulation testifies to the superior performance of the proposed methodology as compared to the maximum likelihood method, and the real-world data analysis examines the applicability and scalability of the proposed methodology
CT, MR, and Angiography Findings of a Solitary Fibrous Tumor of the Larynx: a Case Report
This report details the CT, MR, and angiography findings of a solitary fibrous tumor involving the larynx of a 34-year-old man. A precontrast CT scan revealed a well-defined isodense mass in the submucosal region of the supraglottic larynx. The tumor appeared as a mixed intensity lesion on the T1- and T2-weighted MR images. A T2-weighted MR image showed a central, round, and low signal intensity area within the mass. For both the CT and MR images, the mass demonstrated heterogeneous enhancement following the administration of contrast material. The angiography showed a hypervascular tumor with heterogeneous persistent staining
EFFECTS OF 10 WEEKS TRAINING PROGRAM ON LOWER EXTREMITY STRENGTH AND VERTICAL REACTION FORCE DURING SIT-TO-STAND IN CHRONIC STROKE PATIENTS
The purpose of this study was to investigate the effects of 10 weeks training program on lower extremity strength and' vertical reaction force during sit-to-stand movement in chronic stroke patients. Maximum vertical ground reaction force, difference of vertical ground reaction force between left and right foot, COP in anteriorposterior and mediolateral direction did not show any significant time main effect. However, the difference of body weight distribution between the left and right foot was decreased in experimental group after training. The peak torque generated by the flexors of the paretic limb at 60o /sec and 180o/sec in experimental group changed from baseline, an increases of 30.23% and 24.09%, respectively. These results appear that 10 weeks training program improves sit-to-stand movement and lower extremity strength in chronic stroke patients
Complete response to FOLFOX4 therapy in a patient with advanced urothelial cancer: a case report
No standard has been established for salvage therapy in gemcitabine refractory advanced urothelial cancer. We report the complete response to FOLFOX4 therapy of a metastatic urothelial cancer patient, for whom adjuvant gemcitabine plus cisplatin combination chemotherapy had failed. A 54-year-old male patient with urothelial cancer (transitional cell carcinoma) in the right kidney underwent three rounds of adjuvant gemcitabine-cisplatin chemotherapy after extensive radical nephrectomy. However, he had new liver, lung metastases and synchronous two separate primary colon cancer. The lung metastasis lesion was confirmed as a metastatic urothelial cancer via percutaneous transthoracic needle biopsy (PTNB). Liver and lung metastasis lesions disappeared after the 4th cycle of FOLFOX4 chemotherapy. In addition, colon cancer also disappeared after the 8th cycle of FOLFOX4 chemotherapy. The patient was still showing a complete response after 4 months. Clinical trials using the FOLFOX regimen as salvage therapy for gemcitabine-refractory advanced urothelial cancer are warranted
Semi-Automatic Measurement of the Airway Dimension by Computed Tomography Using the Full-With-Half-Maximum Method: a Study of the Measurement Accuracy according to the Orientation of an Artificial Airway
parameters on the correct measurement of the airway dimension.
Materials and Methods: An airway phantom with 11 poly-acryl tubes of various
lumen diameters and wall thicknesses was scanned using a 16-MDCT (multidetector
CT) at various tilt angles (0, 30, 45, and 60 ). The CT images were reconstructed
at various reconstruction kernels and thicknesses. The axis of each airway
was determined using the 3D thinning algorithm, with images perpendicular to
the axis being reconstructed. The luminal radius and wall thickness was measured
by the full-width-half-maximum method. The influence of the CT parameters (the
size of the airways, obliquity on the radius and wall thickness) was assessed by
comparing the actual dimension of each tube with the estimated values.
Results: The 3D thinning algorithm correctly determined the axis of the oblique
airway in all tubes (mean error: 0.91+-0.82 ). A sharper reconstruction kernel,
thicker image thickness and larger tilt angle of the airway axis resulted in a significant
decrease of the measured wall thickness and an increase of the measured
luminal radius. Use of a standard kernel and a 0.75-mm slice thickness resulted
in the most accurate measurement of airway dimension, which was independent
of obliquity.
Conclusion: The airway obliquity and imaging parameters have a strong influence
on the accuracy of the airway wall measurement. For the accurate measurement
of airway thickness, the CT images should be reconstructed with a
standard kernel and a 0.75 mm slice thickness.This work was supported by the Korea Science and
Engineering Foundation (KOSEF) grant funded by the
Korea government (MOST) (No. R01-2006-000-11244-0)
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