The primary proton spectrum in the kinetic energy range 0.2 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS–91 at an altitude of 380 km. The complete ...data set combining three shuttle attitudes and including all known systematic effects is presented.
Leptons in near earth orbit Ambrosi, G.; Ao, L.; Arefiev, A. ...
Physics letters. B,
06/2000, Letnik:
484, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The lepton spectra in the kinetic energy ranges 0.2 to 40 GeV for e
− and 0.2 to 3 GeV for e
+ were measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS–91 at altitudes ...near 380
km. From the origin of the leptons two distinct spectra were observed: a higher energy spectrum and a substantial second spectrum with positrons much more abundant than electrons. Tracing leptons from the second spectra shows that most of these leptons travel for an extended period of time in the geomagnetic field and that the e
+ and e
− originate from two complementary geographic regions.
Protons in near earth orbit Alcaraz, J.; Ambrosi, G.; Ao, L. ...
Physics letters. B,
2000, Letnik:
472, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The proton spectrum in the kinetic energy range 0.1 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380
km. Above the geomagnetic ...cutoff the observed spectrum is parameterized by a power law. Below the geomagnetic cutoff a substantial second spectrum was observed concentrated at equatorial latitudes with a flux ∼70
m
−2
s
−1
sr
−1. Most of these second spectrum protons follow a complicated trajectory and originate from a restricted geographic region.
Helium in near Earth orbit Ambrosi, G.; Ao, L.; Azzarello, P. ...
Physics letters. B,
2000, Letnik:
494, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The helium spectrum from 0.1 to 100 GeV/nucleon was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at altitudes near 380 km. Above the geomagnetic cutoff the ...spectrum is parameterized by a power law. Below the geomagnetic cutoff a second helium spectrum was observed. In the second helium spectra over the energy range 0.1 to 1.2 GeV/nucleon the flux was measured to be
(6.3±0.9)×10
−3
(
m
2
sec
sr)
−1
and more than ninety percent of the helium was determined to be
3He (at the 90% CL). Tracing helium from the second spectrum shows that about half of the
3He travel for an extended period of time in the geomagnetic field and that they originate from restricted geographic regions similar to protons and positrons.
Search for antihelium in cosmic rays Alcaraz, J.; Alvisi, D.; Ambrosi, G. ...
Physics letters. B,
1999, Letnik:
461, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The Alpha Magnetic Spectrometer (AMS) was flown on the space shuttle Discovery during flight STS-91 in a 51.7° orbit at altitudes between 320 and 390
km. A total of 2.86×10
6 helium nuclei were ...observed in the rigidity range 1 to 140
GV. No antihelium nuclei were detected at any rigidity. An upper limit on the flux ratio of antihelium to helium of <1.1×10
−6 is obtained.
Objectives: The Alexander Project is a continuing surveillance study, begun in 1992, examining the susceptibility of pathogens involved in adult community-acquired respiratory tract infections ...(CARTI) to a range of antimicrobial agents. Materials and methods: This study tested the susceptibility of isolates of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis collected between 1998 and 2000 to 23 antimicrobials. Minimum inhibitory concentrations of agents were determined using the broth microdilution method and interpreted according to NCCLS and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints. Results: In total, 8882 isolates of S. pneumoniae, 8523 isolates of H. influenzae and 874 isolates of M. catarrhalis were collected during 1998–2000 from centres in 26 countries. The world-wide prevalence of penicillin resistance (penicillin MICs ≥ 2 mg/L) in isolates of S. pneumoniae was 18.2% over the study period, and the prevalence of macrolide resistance (erythromycin MICs ≥ 1 mg/L) in this pathogen was 24.6%. Over the study period, macrolide resistance exceeded penicillin resistance in 19 of the 26 countries included in the study. Of the non-fluoroquinolone agents, the only oral agents to which over 90% of S. pneumoniae isolates were susceptible at both NCCLS and PK/PD breakpoints were amoxicillin (95.1%) and co-amoxiclav (95.5–97.9%). The prevalence of fluoroquinolone-resistant S. pneumoniae (ofloxacin MICs ≥ 8 mg/L) was 1.1%. Gemifloxacin was the most potent fluoroquinolone tested against S. pneumoniae (99.9% susceptible). In isolates of H. influenzae, β-lactamase production was 16.9%, whereas the prevalence of β-lactamase-negative, ampicillin-resistant strains was low (0.2%). β-Lactamase production in M. catarrhalis world-wide remained high over the period studied (92.1%). Using PK/PD breakpoints, the most active non-fluoroquinolone agents against H. influenzae were ceftriaxone (100% susceptible), cefixime (99.8%) and co-amoxiclav (98.1–99.6%). Co-amoxiclav, cefdinir and cefixime (100%) were the most active β-lactams against M. catarrhalis. Both H. influenzae and M. catarrhalis were highly susceptible to the fluoroquinolones. Conclusions: These data demonstrate the continued evolution of and geographical variation in bacterial resistance and highlight the need for appropriate prescribing of antimicrobials in CARTI, using agents with adequate activity, based on local susceptibility profiles and PK/PD parameters.
The Alpha Magnetic Spectrometer (AMS) Alcaraz, J.; Ambrosi, G.; Ao, L. ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
02/2002, Letnik:
478, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The Alpha Magnetic Spectrometer (AMS) is a large acceptance (
0.65
sr
m
2
) detector designed to operate in the International Space Station (ISS) for three years. The purposes of the experiment are ...to search for cosmic antimatter and dark matter and to study the composition and energy spectrum of the primary cosmic rays. A “scaled-down” version has been flown on the Space Shuttle Discovery for 10 days in June 1998. The complete AMS is programmed for installation on the ISS in October 2003 for an operational period of
3
yr
. This contribution reports on the experimental configuration that will be installed on the ISS.
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