595 research outputs found
Acyl-Imidazoles A Privileged Ester Surrogate for Enantioselective Synthesis
International audienceSince the first report by Evans in asymmetric FriedelâCrafts reactions, the use of acylâimidazoles has blossomed as powerful ester/amide surrogates. The imidazole scaffold indeed displays stability and special activation features allowing both better reactivity and selectivity in traditional ester/amide functionalizations: αâ(enolate chemistry), ÎČâ(conjugate additions), α,ÎČâ(cycloadditions) or Îł/ÎŽâ(vinylogous). An overview of the contemporary and growing interest in acylâimidazoles in metalâ and organoâcatalyzed transformations (bioâhybrid catalytic systems will be fully described in a backâtoâback Minireview) will be highlighted. Moreover, postâfunctionalization expediencies are also going to be discussed in this Minireview
Using the LeiCNS-PK3.0 physiologically-based pharmacokinetic model to predict brain extracellular fluid pharmacokinetics in mice
The unbound brain extracelullar fluid (brainECF) to plasma steady state partition coefficient, Kp,uu,BBB, values provide steady-state information on the extent of blood-brain barrier (BBB) transport equilibration, but not on pharmacokinetic (PK) profiles seen by the brain targets. Mouse models are frequently used to study brain PK, but this information cannot directly be used to inform on human brain PK, given the different CNS physiology of mouse and human. Physiologically based PK (PBPK) models are useful to translate PK information across species.\nUse the LeiCNS-PK3.0 PBPK model, to predict brain extracellular fluid PK in mice. Information on mouse brain physiology was collected from literature. All available connected data on unbound plasma, brainECF PK of 10 drugs (cyclophosphamide, quinidine, erlotonib, phenobarbital, colchicine, ribociclib, topotecan, cefradroxil, prexasertib, and methotrexate) from different mouse strains were used. Dosing regimen dependent plasma PK was modelled, and Kpuu,BBB values were estimated, and provided as input into the LeiCNS-PK3.0 model to result in prediction of PK profiles in brainECF. Overall, the model gave an adequate prediction of the brainECF PK profile for 7 out of the 10 drugs. For 7 drugs, the predicted versus observed brainECF data was within two-fold error limit and the other 2 drugs were within five-fold error limit. The current version of the mouse LeiCNS-PK3.0 model seems to reasonably predict available information on brainECF from healthy mice for most drugs. This brings the translation between mouse and human brain PK one step further.Pharmacolog
, and the neutrino mass hierarchy at a double baseline Li/B -Beam
We consider a -Beam facility where Li and B ions are
accelerated at , accumulated in a 10 Km storage ring and let
decay, so as to produce intense and beams. These beams
illuminate two iron detectors located at Km and
Km, respectively. The physics potential of this setup is analysed in full
detail as a function of the flux. We find that, for the highest flux ( ion decays per year per baseline), the sensitivity to
reaches ; the sign of
the atmospheric mass difference can be identified, regardless of the true
hierarchy, for ; and, CP-violation
can be discovered in 70% of the -parameter space for , having some sensitivity to CP-violation down to
for .Comment: 35 pages, 20 figures. Minor changes, matches the published versio
Radio emission of extensive air shower at CODALEMA: Polarization of the radio emission along the v*B vector
Cosmic rays extensive air showers (EAS) are associated with transient radio
emission, which could provide an efficient new detection method of high energy
cosmic rays, combining a calorimetric measurement with a high duty cycle. The
CODALEMA experiment, installed at the Radio Observatory in Nancay, France, is
investigating this phenomenon in the 10^17 eV region. One challenging point is
the understanding of the radio emission mechanism. A first observation
indicating a linear relation between the electric field produced and the cross
product of the shower axis with the geomagnetic field direction has been
presented (B. Revenu, this conference). We will present here other strong
evidences for this linear relationship, and some hints on its physical origin.Comment: Contribution to the 31st International Cosmic Ray Conference, Lodz,
Poland, July 2009. 4 pages, 8 figures. v2: Typo fixed, arxiv references adde
Precision on leptonic mixing parameters at future neutrino oscillation experiments
We perform a comparison of the different future neutrino oscillation
experiments based on the achievable precision in the determination of the
fundamental parameters theta_{13} and the CP phase, delta, assuming that
theta_{13} is in the range indicated by the recent Daya Bay measurement. We
study the non-trivial dependence of the error on delta on its true value. When
matter effects are small, the largest error is found at the points where CP
violation is maximal, and the smallest at the CP conserving points. The
situation is different when matter effects are sizable. As a result of this
effect, the comparison of the physics reach of different experiments on the
basis of the CP discovery potential, as usually done, can be misleading. We
have compared various proposed super-beam, beta-beam and neutrino factory
setups on the basis of the relative precision of theta_{13} and the error on
delta. Neutrino factories, both high-energy or low-energy, outperform
alternative beam technologies. An ultimate precision on theta_{13} below 3% and
an error on delta of < 7^{\circ} at 1 sigma (1 d.o.f.) can be obtained at a
neutrino factory.Comment: Minor changes, matches version accepted in JHEP. 30 pages, 9 figure
The MSW Effect in Quantum Field Theory
We show in detail the general relationship between the Schr\"{o}dinger
equation approach to calculating the MSW effect and the quantum field
theoretical S-matrix approach. We show the precise form a generic neutrino
propagator must have to allow a physically meaningful ``oscillation
probability'' to be decoupled from neutrino production fluxes and detection
cross-sections, and explicitly list the conditions---not realized in cases of
current experimental interest---in which the field theory approach would be
useful.Comment: 20 page REVTeX file, submitted to Phys. Rev.
Identifying the Neutrino mass Ordering with INO and NOvA
The relatively large value of established recently by the Daya
Bay reactor experiment opens the possibility to determine the neutrino mass
ordering with experiments currently under construction. We investigate
synergies between the NOvA long-baseline accelerator experiment with
atmospheric neutrino data from the India-based Neutrino Observatory (INO). We
identify the requirements on energy and direction reconstruction and detector
mass for INO necessary for a significant sensitivity. If neutrino energy and
direction reconstruction at the level of 10% and 10 degree can be achieved by
INO a determination of the neutrino mass ordering seems possible around 2020.Comment: 18 pages, 8 figures, minor improvements and clarifications, new panel
in fig. 7, version to appear in JHEP, typo in eq. 4 correcte
Neutrino physics at accelerators
Present and future neutrino experiments at accelerators are mainly concerned
with understanding the neutrino oscillation phenomenon and its implications.
Here a brief account of neutrino oscillations is given together with a
description of the supporting data. Some current and planned accelerator
neutrino experiments are also explained.Comment: 23 pages, 24 figures. Talk given at the Corfu Summer Institute on
Elementary Particle Physics 200
Damping of supernova neutrino transitions in stochastic shock-wave density profiles
Supernova neutrino flavor transitions during the shock wave propagation are
known to encode relevant information not only about the matter density profile
but also about unknown neutrino properties, such as the mass hierarchy (normal
or inverted) and the mixing angle theta_13. While previous studies have
focussed on "deterministic" density profiles, we investigate the effect of
possible stochastic matter density fluctuations in the wake of supernova shock
waves. In particular, we study the impact of small-scale fluctuations on the
electron (anti)neutrino survival probability, and on the observable spectra of
inverse-beta-decay events in future water-Cherenkov detectors. We find that
such fluctuations, even with relatively small amplitudes, can have significant
damping effects on the flavor transition pattern, and can partly erase the
shock-wave imprint on the observable time spectra, especially for
sin^2(theta_13) > O(10^-3).Comment: v2 (23 pages, including 6 eps figures). Typos removed, references
updated, matches the published versio
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