19,239 research outputs found
Ergodicity of the statistic and purity of neutron resonance data
The statistic characterizes the fluctuations of the number of
levels as a function of the length of the spectral interval. It is studied as a
possible tool to indicate the regular or chaotic nature of underlying dynamics,
detect missing levels and the mixing of sequences of levels of different
symmetry, particularly in neutron resonance data. The relation between the
ensemble average and the average over different fragments of a given
realization of spectra is considered. A useful expression for the variance of
which accounts for finite sample size is discussed. An analysis
of neutron resonance data presents the results consistent with a maximum
likelihood method applied to the level spacing distribution.Comment: 24 pages, 19 figures, 1 tabl
Global Maps of Science based on the new Web-of-Science Categories
In August 2011, Thomson Reuters launched version 5 of the Science and Social
Science Citation Index in the Web of Science (WoS). Among other things, the 222
ISI Subject Categories (SCs) for these two databases in version 4 of WoS were
renamed and extended to 225 WoS Categories (WCs). A new set of 151 Subject
Categories (SCs) was added, but at a higher level of aggregation. Since we
previously used the ISI SCs as the baseline for a global map in Pajek (Rafols
et al., 2010) and brought this facility online (at
http://www.leydesdorff.net/overlaytoolkit), we recalibrated this map for the
new WC categories using the Journal Citation Reports 2010. In the new
installation, the base maps can also be made using VOSviewer (Van Eck &
Waltman, 2010).Comment: Scientometrics, in pres
Ample consumption period available until use-by dates: a potential, marketing position for store brands
Traditionally store brands in Australia are viewed with suspicion in regard to their quality and are usually purchased because of the "value for money" that they offer. Australian supermarket majors are considering introducing a new suite of store brands in the higher price brackets. The danger of moving upscale however is that these store brands are relinquishing their value for money appeal and will come head to head with the manufactured brands. Store brands will now require some quality dimension to compete. This paper after studying the attitudes and behavioural response of grocery shoppers to use by dates, is proposing that that the promise of "generous" use-by dates as a surrogate for quality, could be considered as a positioning plank to promote store brands as alternatives to manufactured brands. Logit analysis is employed to explain shoppers' perception and response to use-by dates, of products that they regularly buy, and of alternative products which they have never bought before if the use-by dates of their regular items are perceived to be too shor
Peculiarities in the Spectrum of the Adjoint Scalar Kinetic Operator in Yang-Mills Theory
We study the spectrum of low-lying eigenmodes of the kinetic operator for
scalar particles, in the color adjoint representation of Yang-Mills theory. The
kinetic operator is the covariant Laplacian, plus a constant which serves to
renormalize mass. In the pure gauge theory, our data indicates that the
interval between the lowest eigenvalue and the mobility edge tends to infinity
in the continuum limit. On these grounds, it is suggested that the perturbative
expression for the scalar propagator may be misleading even at distance scales
that are small compared to the confinement scale. We also measure the density
of low-lying eigenmodes, and find a possible connection to multi-critical
matrix models of order m=1.Comment: 9 pages, 14 figure
Shore Platform Processes in Eastern Canada
This research is conducted on a mesotidal, argillite shore platform at Mont Louis in GaspĂ©, QuĂ©bec, and on macrotidal platforms in the basalts of Scots Bay and the sandstones of Burncoat Head in Nova Scotia. Rock samples have been subjected to wetting and drying and to salt weathering cycles. The platforms were surveyed; rock hardness was determined with a Rock Test Hammer; waves were recorded in the field; and downwearing rates were measured at 56 micro-erosion meter stations over 1 to 3 years. Weathering is the dominant process at Mont Louis, although the horizontal platform may have been cut by waves at the high tidal level. Wave backwearing was much more important than downwearing by weathering during the Holocene at Scots Bay. Wave quarrying only occurs on a few scarps today, however, and without much abrasive material, slow downwearing now dominates over most of the platform surface. Waves probably help to remove loosened sand grains at Burncoat Head, thereby contributing to platform downwearing. Abrasion is also important in places, but the data suggest that backwearing by wave quarrying and probably frost has been a little more important than downwearing by abrasion and weathering during the Holocene.Processus des plates-formes littorales de lâest du Canada. Une plate-forme littorale dâargilites soumise Ă des marĂ©es modĂ©rĂ©es Ă Mont Louis en GaspĂ©sie, QuĂ©bec, et des plates-formes soumises Ă des fortes marĂ©es dans les basaltes de Scots Bay et les grĂšs de Burncoat Head de la Nouvelle-Ăcosse furent Ă©tudiĂ©es. Des Ă©chantillons de roches ont Ă©tĂ© soumis Ă des cycles de mouillage et de sĂ©chage et dâhaloclastie. Le profil des plates-formes a Ă©tĂ© mesurĂ©, la duretĂ© des roches a Ă©tĂ© Ă©tablie par le test du marteau de Schmidt, les vagues ont Ă©tĂ© mesurĂ©es sur le terrain et le taux dâusure vertical a Ă©tĂ© quantifiĂ© Ă 56 stations avec des appareils dĂ©tectant la micro-ÂĂ©rosion, le tout sur une pĂ©riode dâun Ă trois ans. LâaltĂ©ration est le processus dominant Ă Mont Louis, bien que la plate-forme horizontale ait Ă©tĂ© entaillĂ©e par les vagues au maximum des marĂ©es hautes. Lâusure horizontale par les vagues Ă©tait plus importante que lâusure verticale par altĂ©ration durant lâHolocĂšne Ă Scots Bay. Lâextraction de grands blocs par les vagues ne se produit toutefois de nos jours que sur quelques abrupts et, en lâabsence de matĂ©riel abrasif, une lente usure verticale domine maintenant sur la plupart des plates-formes. Les vagues ont probablement aidĂ© Ă Ă©liminer les grains de sable produits par lâaltĂ©ration Ă Burncoat Head, contribuant ainsi Ă lâusure verticale de la plate-forme. Lâabrasion est Ă©galement importante Ă certains endroits, mais les donnĂ©es indiquent que lâusure horizontale par les vagues, et aussi par le gel, a Ă©tĂ© un peu plus importante que lâusure verticale par lâabrasion et lâaltĂ©ration durant lâHolocĂšne
Discovery of a Transition to Global Spin-up in EXO 2030+375
EXO 2030+375, a 42-second transient X-ray pulsar with a Be star companion,
has been observed to undergo an outburst at nearly every periastron passage for
the last 13.5 years. From 1994 through 2002, the global trend in the pulsar
spin frequency was spin-down. Using RXTE data from 2003 September, we have
observed a transition to global spin-up in EXO 2030+375. Although the spin
frequency observations are sparse, the relative spin-up between 2002 June and
2003 September observations, along with an overall brightening of the outbursts
since mid 2002 observed with the RXTE ASM, accompanied by an increase in
density of the Be disk, indicated by infrared magnitudes, suggest that the
pattern observed with BATSE of a roughly constant spin frequency, followed by
spin-up, followed by spin-down is repeating. If so this pattern has
approximately an 11 year period, similar to the 15 +/- 3 year period derived by
Wilson et al. (2002) for the precession period of a one-armed oscillation in
the Be disk. If this pattern is indeed repeating, we predict a transition from
spin-up to spin-down in 2005.Comment: Accepted for publication in ApJ Letters, 4 pages, 5 figures, using
emulateapj.cl
Measurement of branching fractions and CP-violating charge asymmetries for B-meson decays to D^(*)D^(*), and implications for the Cabibbo-Kobayashi-Maskawa angle Îł
We present measurements of the branching fractions and charge asymmetries of B decays to all D^(*)D^(*) modes. Using 232Ă10^6 BB pairs recorded on the ΄(4S) resonance by the BABAR detector at the e^+e^- asymmetric B factory PEP-II at the Stanford Linear Accelerator Center, we measure the branching fractions B(B^0âD^(*+)D^(*-))=(8.1±0.6±1.0)Ă10^(-4), B(B^0âD^(*±)D^â)=(5.7±0.7±0.7)Ă10^(-4), B(B^0âD^+D^-)=(2.8±0.4±0.5)Ă10^(-4), B(B^+âD^(*+)D^(*0))=(8.1±1.2±1.2)Ă10^(-4), B(B^+âD^*+D^0)=(3.6±0.5±0.4)Ă10^(-4), B(B^+âD^+D^(*0))=(6.3±1.4±1.0)Ă10^(-4), and B(B^+âD^+D^(0))=(3.8±0.6±0.5)Ă10^(-4), where in each case the first uncertainty is statistical and the second systematic. We also determine the limits B(B^0âD^(*0)D^(*0))<0.9Ă10^(-4), B(B^0âD^(*0)D^0)<2.9Ă10^(-4), and B(B^0âD^0D^0)<0.6Ă10^(-4), each at 90% confidence level. All decays above denote either member of a charge-conjugate pair. We also determine the CP-violating charge asymmetries A(B^0âD^(*±)D^â)=0.03±0.10±0.02, A(B^+âD^(*+)D^(*0))=-0.15±0.11±0.02, A(B^+âD^(*+)D^0)=-0.06±0.13±0.02, A(B^+âD^+D^(*0))=0.13±0.18±0.04, and A(B^+âD^+D^0)=-0.13±0.14±0.02. Additionally, when we combine these results with information from time-dependent CP asymmetries in B^0âD^((*)+)D^((*)-) decays and world-averaged branching fractions of B decays to D_s^(*)D^(*) modes, we find the Cabibbo-Kobayashi-Maskawa phase Îł is favored to lie in the range (0.07â2.77) radians (with a +0 or +Ï radians ambiguity) at 68% confidence level
Study of the decay B^0âD^(*+)ÏÏ^-
We report on a study of the decay B^0âD^(*+)ÏÏ^- with the BABAR detector at the PEP-II B-factory at the Stanford Linear Accelerator Center. Based on a sample of 232Ă10^6 BB decays, we measure the branching fraction B(B^0âD^(*+)ÏÏ^-)=(2.88±0.21(stat.)±0.31(syst.))Ă10^(-3). We study the invariant mass spectrum of the ÏÏ^- system in this decay. This spectrum is in good agreement with expectations based on factorization and the measured spectrum in Ï-âÏÏ-Îœ_Ï. We also measure the polarization of the D^(*+) as a function of the ÏÏ^- mass. In the mass region 1.1 to 1.9 GeV we measure the fraction of longitudinal polarization of the D^(*+) to be ÎL/Î=0.654±0.042(stat.)±0.016(syst.). This is in agreement with the expectations from heavy-quark effective theory and factorization assuming that the decay proceeds as B^(-0)âD^(*+)Ï(1450)-, Ï(1450)^-âÏÏ^-
Search for the decay Ï-â3Ï^-2Ï^+2Ï^0Îœ_Ï
A search for the decay of the Ï lepton to five charged and two neutral pions is performed using data collected by the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider. The analysis uses 232ââfb^(-1) of data at center-of-mass energies on or near the ΄(4S) resonance. We observe 10 events with an expected background of 6.5_(-1.4)^(+2.0) events. In the absence of a signal, we set the limit on the branching ratio B(Ï-â3Ï^-2Ï^+2Ï^0Îœ_Ï)<3.4Ă10^(-6) at the 90% confidence level. This is a significant improvement over the previously established limit. In addition, we search for the decay mode Ï-â2ÏÏ-Îœ_Ï. We observe 1 event with an expected background of 0.4+1.0/-0.4 events and calculate the upper limit B(Ï-â2ÏÏ-Îœ_Ï)<5.4Ă10^(-7) at the 90% confidence level. This is the first upper limit for this mode
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