130 research outputs found
Search for Antimatter in Space with the Alpha Magnetic Spectrometer
The Alpha Magnetic Spectrometer (AMS) is a state of the art particle physics
experiment for the extraterrestrial study of antimatter, matter and missing
matter. AMS successfully completed the precursor STS91 Discovery flight (June
2nd-12th, 1998), completing 152 orbits at 52 degrees of latitude and about 400
km of height, collecting more than 100 million CR events. In this paper we
report on the first flight experience and we present preliminary results on the
search for nuclear antimatter. No antimatter nuclei with Z>=2 were detected. We
obtain a model dependent upper limit on the anti-He /He flux <1.14 10^^-6 In
the rigidity region between 1.6 to 20 GV we obtain a model independent,
conservative upper limit on anti-He /He flux <1.7 10^^-6 and <2.8 10^^-5 for
Z>2, improving the results of previous published searches performed with
stratospheric balloons.Comment: 1 tex file, 15 pages, 11 figures ps.gz file
Precision measurements of e+e− in Cosmic Ray with the Alpha Magnetic Spectrometer on the ISS
AbstractOne hundred years after their discovery by Victor Hess, Cosmic Rays are nowadays subject of intense research from space based detectors, able to perform for the first time high precision measurement of their composition and spectra as well as of isotropy and time variability. On May 2011, the Alpha Magnetic Spectrometer (AMS-02), has been installed on the International Space Station, to measure with high accuracy the Cosmic Rays properties searching for rare events which could be indication of the nature of Dark Matter or presence of nuclear Antimatter. AMS-02 is the result of nearly two decades of effort of an international collaboration, to design and build a state of the art detector capable to perform high precision Cosmic Rays measurement. In this paper I will briefly report on the first results of AMS-02 two years after the beginning of the operations in space
A lament for Italy's brain drain
only omissions are the importance of private conservation as a stepping-stone for devolved wildlife management, and why wildlife offers an economic solution in some of Africa's agriculturally marginal environments. Southern Africa has collectively grasped the nettle, taking a leap that has revolutionary implications for conservation practice. Deeply committed scholar practitioners attempted to fast-track the empowerment of communities. But although it was initially highly successful, this strategy is now facing the challenge of 'aborted devolution', as politically motivated elite groups try to grab wildlife resources for themselves. The book offers the frank and honest observation that, although the underlying concepts appear to hold and to offer the best way forward, most community-conservation initiatives survive only through the efforts of rare individuals or by external financial support. There is sufficient evidence that community conservation, when properly applied, works, and can do the greatest good for the greatest number. Yet proper application remains the exception rather than the norm. Its weakness lies in the assumption that the concept of the greatest good is a winning formula for bringing about institutional change. Particularly in non-democratic countries, there is much evidence to the contrary. ■ Brian Child is a conservationist based in Cape Town, South Africa. A lament for Italy's brain drai
Jesu li vrste Empusa pennata i Bolivaria brachyptera doista prisutne u Hrvatskoj? Odgovor Kranjčevu (2013) s kritičkim osvrtom na vrste bogomoljki prisutne u Hrvatskoj
Radovan Kranjčev (2013) published a paper on Croatian Mantodea containing a considerable number of data that need to be discussed. In this reply corrections of mantid misidentifications, as well as of some given statements, are presented, certain doubtful records are discussed and comments on a number of overlooked papers are given. Also, a critical review of some further problems concerning Croatian Mantodea fauna is presented, as well as a rather short historical overview of investigations of this insect order in Croatia.Radovan Kranjčev (2013) objavio je rad o bogomoljkama Hrvatske u kojem je iznesen znatan broj podataka koje je potrebno raspraviti. U ovom odgovoru doneseni su ispravci determinacija nekih bogomoljki, kao i određenih navoda, raspravljeni su neki upitni nalazi i dani su komentari na neke previđene radove. Također, predstavljen je osvrt na tekuće probleme vezane uz faunu bogomoljki Hrvatske, kao i vrlo kratki povijesni pregled istraživanja ovog reda kukaca u Hrvatskoj
Cause ed effetti dei cambiamenti climatici
In questo articolo cerco di dare una semplice panoramica sul tema dei cambiamenti climatici. Una corretta informazione di base deve fare parte del bagaglio culturale di ogni persona che voglia essere in grado di discutere di questi temi. Ce n'è davvero bisogno: sono moltissimi, infatti, gli interessi che rallentano le azioni correttive o addirittura contestano l'esistenza del problema. La scienza ha da tempo fatto la sua parte nel chiarire cosa sta succedendo e non saranno mai troppe le persone che siano in grado di passare in modo autorevole e informato questo messaggio nella società
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