4,289 research outputs found
New results on atmospheric neutrinos from Soudan 2
Neutrino interactions recorded in a 5.1 fiducial kiloton-year exposure of the
Soudan-2 iron tracking calorimeter are analyzed for effects of neutrino
oscillations. Using contained single track and single shower events, we update
our measurement of the atmospheric nu_mu/nu_e ratio-of-ratios and find R = 0.68
\pm 0.11 \pm 0.06. Assuming this anomalously low R-value is the result of nu_mu
flavor disappearance via nu_mu to nu_tau oscillation, we select samples of
charged current events which offer good resolution, event-by-event, for L/Enu
reconstruction. Oscillation-weighted Monte Carlo events are fitted to these
data events using a chisq function summed over bins of log(L/E_nu). The region
allowed in the (sin^2 2\theta, \Delta m^2) plane at 90% CL is obtained using
the Feldman-Cousins procedure: 0.46 < sin^2 2\theta < 1.0 and 2.2x10^-4 <
\Delta m^2 < 2.2x10^-2 ev^2. A small but relatively energetic sample of
partially contained nu_mu events has also been isolated. Their distribution in
log(L/E_vis) relative to null oscillation Monte Carlo is compatible with nu_mu
to nu_tau oscillation scenarios within the parameter region allowed by our
contained events.Comment: 7 pages, 7 figures; presented at NU2000, the XIXth Int. Conf. on
Nuetrino Physics and Astrophysics, June 16-21, 2000, Sudbury, canad
Education Curriculum
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Private focus on public spaces : an exercise in photographic construction
Orientador: Mauricius Martins FarinaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de ArtesResumo: Villém Flússer propõe em seu texto Filosofia da Caixa Preta dois conceitos opostos que desafiam a autonomia criativa no fazer fotográfico. Se "funcionário" é operador do aparelho e age de acordo com programa pós-industrial revestido em seu interior, a figura do "fotógrafo" vem acrescentar uma possibilidade de subversão a esse programa. Esta capacidade demonstra-se então bem relativa pois é da natureza do aparelho servir-se da criatividade do fotógrafo criando novos programas que aumentarão as exigências do desvio. Haverá então repertório infinito para novas imagens? Esta pesquisa propõe apontar alguns paralelos entre uma fotografia na qual a documentalidade vinculada a um imaginário fortemente calcado no realismo perspectivista é marca aparente, e uma fotografia que procura finalmente transcender os programas impostos por esta visão aparelhística. Procurou-se exemplos desta problematização em obras heterogêneas como a de Rodtchencko, August Sander e Bernd & Hilla Becher, incluindo também, no último caso, as escolas fundadas a partir de suas metodologias de abordagem entre objeto e referente. Ponto capital na análise de cada obra é o domínio rigoroso da sintaxe fotográfica demonstrada por cada autor, mesmo que, o grau de contingencialidade prevaleça mais em uns que em outros. De forma dialógica, esta pesquisa ainda propõe apontar certos aspectos onde o domínio da programaticidade e da retilinearidade do aparelho escapa a raros estados em que a fotografia não mais se coloca como uma construção semântica codificada por elementos geométricos historicamente convencionados, mas como Barthes nos diz: como "uma força constativa", ao "isto é" e "isto foi", no qual o noema não parte do objeto, mas do tempo. Se este é o caminho para a renovação da fotografia a idéia da liberdade do fotógrafo adquire contornos diversos ao que foi apresentado por Flússer. Concomitante à revisão da literatura, a outra metade do desenvolvimento desta pesquisa compreende um exercício de construção fotográfica em forma de tipologias com móveis domésticos descartados no ambiente urbano, Esta proposta prática é indissociável aos conceitos teóricos aqui propostosAbstract: Villem Flusser suggested in his text "Towards a Philosophy of Photography" two opposite ideas which challenge the creative autonomy in making photography. If the "worker" is the "operator" of the apparatus and act according to the postindustrial program inward cover, the "photographer" come to add more subversive possibilities to the program. This capacity then demonstrate relativity for it's the apparatus nature to serve the creativity of the photographer creating new programs which adds the demand of diversion. Then there will be a repertory of infinite new image? The proposal of this research is to show some parallels between the photography in which a imaginary documental links strongly - stepped on realistic perspective which is the aparent mark, a photography which search firmly to beyound of its program impose for this visual apparatus. Looking after example of this question in heterogeneous work, like Rodtchencko, August Sander and Bernd & Hilla Becher, which includes also in the last case, the school founded, starting on its methodic approach between object and reference. The analitical highpoint in each work is the rigorous dominion of the photographic sintax demonstrated by each author inspite the degree of contingency that prevails, mor or less at each others. The dialogical form of this research again, suggest certain aspects where dominion of programaticity and the retilianerity of the apparatus escape to rare moments in which photography doesn't set like a semantic construction codified by geometrical elements historically agreed, but as Barthes have said, "confirmed force", a "that is" / "that was" in which perception (noema) don't start from the object, but from time. If this is the way of the photographic renovation, the idea of the emancipation of the photographer acquires diverse configuration which on presented by Flússer. Together with the literary revision, the other half of the development understand the practice of the photographic construction in the tipological form with cast-off household furniture in the urban environment. This practical proposal is unseparable with the theorical ideas as proposeMestradoArtes VisuaisMestre em Arte
Testing Bell's inequality with two-level atoms via population spectroscopy
We propose a feasible experimental scheme, employing methods of population
spectroscopy with two-level atoms, for a test of Bell's inequality for massive
particles. The correlation function measured in this scheme is the joint atomic
function. An inequality imposed by local realism is violated by any
entangled state of a pair of atoms.Comment: 4 pages, REVTeX, no figures. More info on
http://www.ligo.caltech.edu/~cbrif/science.htm
Measurement of the traction force of biological cells by digital holography
The traction force produced by biological cells has been visualized as distortions in flexible substrata. We have utilized quantitative phase microscopy by digital holography (DH-QPM) to study the wrinkling of a silicone rubber film by motile fibroblasts. Surface deformation and the cellular traction force have been measured from phase profiles in a direct and straightforward manner. DH-QPM is shown to provide highly efficient and versatile means for quantitatively analyzing cellular motility
CMB Signals of Neutrino Mass Generation
We propose signals in the cosmic microwave background to probe the type and
spectrum of neutrino masses. In theories that have spontaneous breaking of
approximate lepton flavor symmetries at or below the weak scale, light
pseudo-Goldstone bosons recouple to the cosmic neutrinos after nucleosynthesis
and affect the acoustic oscillations of the electron-photon fluid during the eV
era. Deviations from the Standard Model are predicted for both the total energy
density in radiation during this epoch, \Delta N_nu, and for the multipole of
the n'th CMB peak at large n, \Delta l_n. The latter signal is difficult to
reproduce other than by scattering of the known neutrinos, and is therefore an
ideal test of our class of theories. In many models, the large shift, \Delta
l_n \approx 8 n_S, depends on the number of neutrino species that scatter via
the pseudo-Goldstone boson interaction. This interaction is proportional to the
neutrino masses, so that the signal reflects the neutrino spectrum. The
prediction for \Delta N_nu is highly model dependent, but can be accurately
computed within any given model. It is very sensitive to the number of
pseudo-Goldstone bosons, and therefore to the underlying symmetries of the
leptons, and is typically in the region of 0.03 < \Delta N_nu < 1. This signal
is significantly larger for Majorana neutrinos than for Dirac neutrinos, and,
like the scattering signal, varies as the spectrum of neutrinos is changed from
hierarchical to inverse hierarchical to degenerate.Comment: 40 pages, 4 figure
AAT Imaging and Microslit Spectroscopy in the Southern Hubble Deep Field
We present a deep photometric (B- and R-band) catalog and an associated
spectroscopic redshift survey conducted in the vicinity of the Hubble Deep
Field South. The spectroscopy yields 53 extragalactic redshifts in the range
0<z<1.4 substantially increasing the body of spectroscopic work in this field
to over 200 objects. The targets are selected from deep AAT prime focus images
complete to R<24 and spectroscopy is 50% complete at R=23. There is now strong
evidence for a rich cluster at z\simeq 0.58 flanking the WFPC2 field which is
consistent with a known absorber of the bright QSO in this field. We find that
photometric redshifts of z<1 galaxies in this field based on HST data are
accurate to \sigma_z/(1+z)=0.03 (albeit with small number statistics). The
observations were carried out as a community service for Hubble Deep Field
science, to demonstrate the first use of the `nod & shuffle' technique with a
classical multi-object spectrograph and to test the use of `microslits' for
ultra-high multiplex observations along with a new VPH grism and deep-depletion
CCD. The reduction of this new type of data is also described.Comment: From the better late than never department: AJ in press (2006). 16
pages, 2 tables, 6 figures, final data release + Appendix at
http://www.aao.gov.au/hdfs/Redshifts
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