Using a high statistics sample of photoproduced charm particles from the FOCUS experiment at Fermilab, we compare the lifetimes of neutral
D mesons decaying via
D
0→K
−π
+
and
K
−K
+
to measure the ...lifetime differences between CP even and CP odd final states. These measurements bear on the phenomenology of
D
0−
D
̄
0
mixing. If the
D
0→
K
−
π
+ is an equal mixture of CP even and CP odd eigenstates, we measure
y
CP
=(Γ(
CP
even
)−Γ(
CP
odd
))/(Γ(
CP
even
)+Γ(
CP
odd
))=0.0342±0.0139±0.0074
.
The properties of the nuclear modification factor for heavy flavors are usually attributed to the energy loss suffered by the heavy quark propagating in a QCD plasma. Nevertheless it is a bit ...surprising that the suppression of this factor is as strong as the one suffered by light flavors. In this work we show that when accounting for the momentum shift associated to the opening of the recombination channel to produce hadrons in the QCD plasma, it is not necessary to invoke such a strong energy loss. We show that when the heavy baryon to meson ratio is larger in nuclear than in proton collisions, data from RHIC and LHC for the nuclear modification factor of electrons coming from heavy flavor decays as well as for charmed masons can be accounted for.
The photosynthetic bacterium,
Rhodobacter capsulatus, produces hydrogen under nitrogen-limited, anaerobic, photosynthetic culture conditions, using various carbon substrates. In the present study, ...the relationship between light intensity and hydrogen production has been modelled in order to predict both the rate of hydrogen production and the amount of hydrogen produced at a given time during batch cultures of
R. capsulatus. The experimental data were obtained by investigating the effect of different light intensities (6000–50,000
lux) on hydrogen-producing cultures of
R. capsulatus grown in a batch photobioreactor, using lactate as carbon and hydrogen source. The rate of hydrogen production increased with increasing light intensity in a manner that was described by a static Baly model, modified to include the square of the light intensity. In agreement with previous studies, the kinetics of substrate utilization and growth of
R. capsulatus was represented by the classical Monod or Michaelis–Menten model. When combined with a dynamic Leudekong–Piret model, the amount of hydrogen produced as a function of time was effectively predicted. These results will be useful for the automatization and control of bioprocesses for the photoproduction of hydrogen.
Mass spectrometry combined with database searching has become the preferred method for identifying proteins in proteomics projects. Proteins are digested by one or several enzymes to obtain peptides, ...which are analyzed by mass spectrometry. We introduce a new family of scoring schemes, named OLAV, aimed at identifying peptides in a database from their tandem mass spectra. OLAV scoring schemes are based on signal detection theory, and exploit mass spectrometry information more extensively than previously existing schemes. We also introduce a new concept of structural matching that uses pattern detection methods to better separate true from false positives. We show the superiority of OLAV scoring schemes compared to MASCOT, a widely used identification program. We believe that this work introduces a new way of designing scoring schemes that are especially adapted to high‐throughput projects such as GeneProt large‐scale human plasma project, where it is impractical to check all identifications manually.
We compute the pion inclusive transverse momentum distribution assuming thermal equilibrium together with transverse flow and accounting for finite size effects and energy loss at the time of ...decoupling. We compare to data on mid-rapidity pions produced in central collisions in RHIC at sNN=200 GeV. We find that a finite size for the system of emitting particles results in a power-like fall-off of the spectra that follows the data up to larger pt values, as compared to a simple thermal model.
We study Λc± production in pN and π−N interactions. Recent experimental data from the SELEX and E791 Collaborations at FNAL provide important information on the production mechanism of charm hadrons. ...In particular, the production of the Λc baryon provides a good test of the intrinsic charm and the recombination mechanisms, which have been proposed to explain the so-called leading particle effects.
We study the behavior of the ρ vector mass in the context of the almost baryon-free environment of an ultra-relativistic heavy-ion collision. We show that ρ scattering within the hadronic phase of ...the collision leads to a temperature dependent, decrease of its intrinsic mass at rest, compared to the value in vacuum. The main contributions arise from s-channel scattering with pions through the formation of a1 resonances as well as with nucleons through the formation of even parity, spin 3/2 N(1720) and 5/2 Δ(1905) nucleon resonances. We show that it is possible to achieve a shift in the intrinsic ρ0 mass of order ∼−40 MeV, when including the contributions of all the relevant mesons and baryons that take part in the scattering, for temperatures between chemical and kinetic freeze-out.
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