sábado, 18 de julho de 2015
STEREO : imagem do sol
This image of the sun was taken on July 15,
2015, with the Extreme Ultraviolet Imager onboard NASA's Solar
TErrestrial RElations Observatory Ahead (STEREO-A) spacecraft, which
collects images in several wavelengths of light that are invisible to
the human eye. This image shows the sun in wavelengths of 171 angstroms,
typically colorized in blue.
sexta-feira, 17 de julho de 2015
site: http://www.nobelprize.org/nobel_prizes/themes/physics/karlsson/index.html
The Nobel Prize in Physics 1901-2000
by Erik B.
Karlsson*
What Is Physics?
Physics is considered to be the most basic of the natural sciences. It deals with the fundamental constituents of matter and their interactions as well as the nature of atoms and the build-up of molecules and condensed matter. It tries to give unified descriptions of the behavior of matter as well as of radiation, covering as many types of phenomena as possible. In some of its applications, it comes close to the classical areas of chemistry, and in others there is a clear connection to the phenomena traditionally studied by astronomers. Present trends are even pointing toward a closer approach of some areas of physics and microbiology.Although chemistry and astronomy are clearly independent scientific disciplines, both use physics as a basis in the treatment of their respective problem areas, concepts and tools. To distinguish what is physics and chemistry in certain overlapping areas is often difficult. This has been illustrated several times in the history of the Nobel Prizes. Therefore, a few awards for chemistry will also be mentioned in the text that follows, particularly when they are closely connected to the works of the Physics Laureates themselves. As for astronomy, the situation is different since it has no Nobel Prizes of its own; it has therefore been natural from the start, to consider discoveries in astrophysics as possible candidates for Prizes in Physics.
quarta-feira, 15 de julho de 2015
terça-feira, 14 de julho de 2015
Física das Partículas
Pentaquark
In 2003 came experimental evidence of a five-quark combination which is being called a pentaquark. Strong evidence for the pentaquark came from experiments at the Jefferson Lab in Newport News, Virginia during 2003. The experiments involved multi-GeV photons impacting a deuterium target. The evidence showed a five-quark baryon state at a mass of 1.54 GeV with a narrow width of 22 MeV. The new particle is being called Theta-plus, with a composition of two up quarks, two down quarks and an anti-strange quark. The combination of quark charges +2/3(u), -1/3 (d) and 1/3 (anti-strange) gives a net charge of +1. The lifetime of the particle is about 10-20 seconds. The decay is classified as a strong interaction decay to a neutron and a K+ meson
While the postulated pentaquark has made an interesting story, continued experimentation has not borne it out. The 2006 Particle Data Group publication expressed its pessimism with the statement "There has not been a high-statistics confirmation of any of the original experiments that claimed to see the θ+; there have been two high-statistics repeats from Jefferson Lab that have clearly shown the original positive claims in those two cases to be wrong; there have been a number of other high-statistics experiments, none of which have found any evidence for the θ+; and all attempts to confirm the two other claimed pentaquark states have led to negative results. The conclusion that pentaquarks in general, and the θ+, in particular, do not exist, appears compelling."
The statement in the 2008 Summary was even stronger, and the issue appears to have been dropped from the 2010 Summary, so the consensus seems strong that this particular quark combination has not been observed.
| Table of Baryons | Table of Mesons |
Python
Slides das aulas teóricas
- Aula 2 (24 set): Introdução à linguagem Python
- Aula 3 (29 set): Primeiros programas
- Aula 4 (1 out): Definição de funções
- Aula 5 (6 out): Ciclos e condicionais
- Aula 6 (15 out): Números pseudo-aleatórios
- Aula 7 (22 out): Resolução numérica de equações
- Aula 8 (27 out): Cadeias de carateres
- Aula 9 (29 out): Listas e tuplos
- Aula 10 (3 nov): Processamento de listas
- Aula 11 (5 nov): Mais sobre ciclos e iteração
- Aula 12 (10 nov): Mais sobre cadeias e listas
- Aula 13 (12 nov): Manipulação de ficheiros
- Aula 14 (17 nov): Dicionários
- Aula 15 (19 nov): Definições recursivas
- Aula 16 (24 nov): Mais exemplos de recursão
- Aula 17 (26 nov): Deteção e correção de erros
- Aula 18 (1 dez): Método de eliminação de Gauss
- Aula 19 (3 dez): Programação com objetos
- Aula 20 (10 dez): Definição de classes
segunda-feira, 13 de julho de 2015
domingo, 12 de julho de 2015
sexta-feira, 10 de julho de 2015
A fortuna acumulada pelos dez multimilionários mais ricos de França ascende a 194.400 milhões de euros, muito acima dos 179.081 milhões do Produto Interno Bruto da Grécia em 2014, publicou a revista “Challenges”. O primeiro lugar desta classificação daquela revista económica é ocupado pelo empresário Bernard Arnault e pela sua família, que controlam o grupo de produtos de luxo LVMH.
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