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1.
Phys Rev Lett ; 114(17): 171103, 2015 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-25978222

RESUMO

A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge of the rigidity dependence of the proton flux is important in understanding the origin, acceleration, and propagation of cosmic rays. We present the detailed variation with rigidity of the flux spectral index for the first time. The spectral index progressively hardens at high rigidities.

2.
Phys Rev Lett ; 113(22): 221102, 2014 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-25494065

RESUMO

We present a measurement of the cosmic ray (e^{+}+e^{-}) flux in the range 0.5 GeV to 1 TeV based on the analysis of 10.6 million (e^{+}+e^{-}) events collected by AMS. The statistics and the resolution of AMS provide a precision measurement of the flux. The flux is smooth and reveals new and distinct information. Above 30.2 GeV, the flux can be described by a single power law with a spectral index γ=-3.170±0.008(stat+syst)±0.008(energy scale).

3.
Phys Rev Lett ; 113(12): 121102, 2014 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-25279617

RESUMO

Precision measurements by the Alpha Magnetic Spectrometer on the International Space Station of the primary cosmic-ray electron flux in the range 0.5 to 700 GeV and the positron flux in the range 0.5 to 500 GeV are presented. The electron flux and the positron flux each require a description beyond a single power-law spectrum. Both the electron flux and the positron flux change their behavior at ∼30 GeV but the fluxes are significantly different in their magnitude and energy dependence. Between 20 and 200 GeV the positron spectral index is significantly harder than the electron spectral index. The determination of the differing behavior of the spectral indices versus energy is a new observation and provides important information on the origins of cosmic-ray electrons and positrons.

4.
Phys Rev Lett ; 113(12): 121101, 2014 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-25279616

RESUMO

A precision measurement by AMS of the positron fraction in primary cosmic rays in the energy range from 0.5 to 500 GeV based on 10.9 million positron and electron events is presented. This measurement extends the energy range of our previous observation and increases its precision. The new results show, for the first time, that above ∼200 GeV the positron fraction no longer exhibits an increase with energy.

5.
J Med Eng Technol ; 33(6): 449-53, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19479607

RESUMO

Humidity and temperature are considered to be important factors in designing comfortable seat surfaces. A small number of studies have attempted to address this;however the methods used were limited regarding the placement of their sensors. This study aimed to design a sensor array system to investigate changes in humidity and temperature for eventual use in the study of factors affecting sitting comfort and incontinence detection. The system was subjected to three types of experiments: sensor response verification, thermal radiation testing and in situ trials. The variance in output within each type of sensor was small (+3.5% and +0.38 degrees C) and there was no apparent change to the variance in output of the sensors, when used in air or on a foam cushion loaded with a 50 kg sand bag (p > 0.1). In the human sitting experiments, although the profile from sensors under the thighs and ischial tuberosities were similar, the magnitude of change could be affected by position and body mass of the subject. This was especially noticeable with the sensors under the coccyx. These results support the use of multiple sites for sensor placement over the use of a single site when studying these parameters at the interface between subject and seating material at the seat base.


Assuntos
Umidade , Temperatura , Adulto , Desenho de Equipamento , Feminino , Humanos , Masculino , Postura , Adulto Jovem
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