Infrared Exponents and the Running Coupling of Landau gauge QCD and their Relation to Confinement

The infrared behaviour of the gluon and ghost propagators in Landau gauge QCD is reviewed. The Kugo-Ojima confinement criterion and the Gribov-Zwanziger horizon condition result from quite general properties of the ghost Dyson-Schwinger equation. The numerical solutions for the gluon and ghost propagators obtained from a truncated set of Dyson-Schwinger equations provide an explicit example for the anticipated infrared behaviour. The results are in good agreement with corresponding lattice data obtained recently. The resulting running coupling approaches a fix point in the infrared, $\alpha(0) = 8.92/N_c$. Two different fits for the scale dependence of the running coupling are given and discussed.Comment: 3 pages, 3 figures; talk given by R.A. at the conference Quark Nuclear Physics 200

Smart magnetic resonance imaging agents relevant to potential neurological applications

International audienceMolecular imaging is aimed at the noninvasive visualization of the expression and function of bioactive molecules that often represent specific molecular signatures in disease processes. Any molecular imaging procedure requires an imaging probe that is specific to a given molecular event, which puts an important emphasis on chemistry development. In MR imaging, the past years have witnessed significant advances in the design of molecular agents, though most of these efforts have not yet progressed to in vivo studies. In this review, we present some examples relevant to potential neurobiologic applications. Our aim was to show what chemistry can bring to the area of molecular MR imaging with a focus on the 2 main classes of imaging probes: Gd3+-based and PARACEST agents. We will discuss responsive probes for the detection of metal ions such as Ca, Zn, Fe, and Cu, pH, enzymatic activity, and oxygenation state

Dissolved iron distribution in the tropical and sub tropical south eastern Pacific

International audienceDissolved iron (DFe) distributions (Fe:P (PO43-) we show that DFe was in deficit compared to PO43- resulting from the remineralisation of organic matter. This suggests that the Marquesas islands and the surrounding plateau are not a significant source of DFe. In the gyre, DFe concentrations in the upper 350 m water column were around 0.1 nM and the ferricline was located well below the nitracline. These low concentrations reflect the low input of DFe from the atmosphere, from the ventilation of the upper thermocline with water containing low DFe, and from the low biological activity within in this ultra oligotrophic gyre

Short report: molecular markers associated with Plasmodium falciparum resistance to sulfadoxine-pyrimethamine in the Democratic Republic of Congo.

Sulfadoxine-pyrimethamine (SP) is the first line antimalarial treatment in the Democratic Republic of Congo. Using polymerase chain reaction, we assessed the prevalence of mutations in the dihydrofolate reductase (dhfr) (codons 108, 51, 59) and dihydropteroate synthase (dhps) (codons 437, 540) genes of Plasmodium falciparum, which have been associated with resistance to pyrimethamine and sulfadoxine, respectively. Four hundred seventy-four patients were sampled in Kilwa (N = 138), Kisangani (N = 112), Boende (N = 106), and Basankusu (N = 118). The proportion of triple mutations dhfr varied between sites but was always > 50%. The proportion of dhps double mutations was < 20%, with some sites as low as 0.9%. A quintuple mutation was present in 12.8% (16/125) samples in Kilwa; 11.9% (13/109) in Kisangani, 2.9% (3/102) in Boende, and 0.9% (1/112) in Basankusu. These results suggest high resistance to pyrimethamine alone or combined with sulfadoxine. Adding artesunate to SP does not seem a valid alternative to the current monotherapy

Pension disparities between men and women: which evolutions?

Mens and womens pensions and retirement ages remain very different, even if this gap has been closing (slowly) for the most recent generations. This work analyses possible developments till 2040. We first study the impact on future pension entitlements and on disparities between genders of the rise in womens participation in the labour market since the early 70s. Simulations carried out with the Destinie microsimulation model conclude that the gender gap keeps closing by the year 2040, essentially because of the rise in womens years of contribution. In a second part, we study the gender impact of pension reforms since the 90s. Although these reforms do not differentiate explicitly between genders, they can have diverging impacts for men and women due to interactions between the new rules and career profiles. Simulations show that this is actually the case. Without reforms, the ratio between pensions for men and women in the private sector would have fallen from 1,99 for cohorts 1940-44 to 1,47 for cohorts 1965-74. After reforms, the new ratio is expected to be 1,59. But the underlying mechanisms are very different from one reform to the next. The 1993 reform has the largest impact: computing the reference wage on the 25 rather than the 10 best years of ones career is more penalizing for women. The impact of the 2003 reform rather results from the fact that women make a larger use of new possibilities to retire before reaching the full rate. The relative reduction of their pension level is therefore the counterpart of an earlier age at benefit claiming. In the public sector, the same 2003 reform is a little more penalizing for men.Pension system, microsimulation, Destinie, pension reform, gender

A Search for Exozodiacal Dust and Faint Companions Near Sirius, Procyon, and Altair with the NICMOS Coronagraph

We observed Sirius, Altair, and Procyon with the NICMOS Coronagraph on the Hubble Space Telescope to look for scattered light from exozodiacal dust and faint companions within 10 AU from these stars. We did not achieve enough dynamic range to surpass the upper limits set by IRAS on the amount of exo-zodiacal dust in these systems, but we did set strong upper limits on the presence of nearby late-type and sub-stellar companions.Comment: 10 pages, 4 figure

Contrasted Saharan dust events in LNLC environments: impact on nutrient dynamics and primary production

The response of the phytoplanktonic community (primary production and algal biomass) to contrasted Saharan dust events (wet and dry deposition) was studied in the framework of the DUNE ("a DUst experiment in a low-Nutrient, low-chlorophyll Ecosystem") project. We simulated realistic dust deposition events (10 gm(-2)) into large mesocosms (52m(3)). Three distinct dust addition experiments were conducted in June 2008 (DUNE-1-P: simulation of a wet deposition; DUNE-1-Q: simulation of a dry deposition) and 2010 (DUNE-2-R1 and DUNE-2-R2: simulation of two successive wet depositions) in the northwestern oligotrophic Mediterranean Sea. No changes in primary production (PP) and chlorophyll a concentrations (Chl a) were observed after a dry deposition event, while a wet deposition event resulted in a rapid (24 h after dust addition), strong (up to 2.4-fold) and long (at least a week in duration) increase in PP and Chl a. We show that, in addition to being a source of dissolved inorganic phosphorus (DIP), simulated wet deposition events were also a significant source of nitrate (NO3-) (net increases up to +9.8 mu M NO3- at 0.1m in depth) to the nutrient-depleted surface waters, due to cloud processes and mixing with anthropogenic species such as HNO3. The dry deposition event was shown to be a negligible source of NO3-. By transiently increasing DIP and NO3- concentrations in N-P starved surface waters, wet deposition of Saharan dust was able to relieve the potential N or NP co-limitation of the phytoplanktonic activity. Due to the higher input of NO3- relative to DIP, and taking into account the stimulation of the biological activity, a wet deposition event resulted in a strong increase in the NO3-/DIP ratio, from initially less than 6, to over 150 at the end of the DUNE-2-R1 experiment, suggesting a switch from an initial N or NP co-limitation towards a severe P limitation. We also show that the contribution of new production to PP strongly increased after wet dust deposition events, from initially 15% to 60-70% 24 h after seeding, indicating a switch from a regenerated-production based system to a new-production based system. DUNE experiments show that wet and dry dust deposition events induce contrasting responses of the phytoplanktonic community due to differences in the atmospheric supply of bioavailable new nutrients. Our results from original mesocosm experiments demonstrate that atmospheric dust wet deposition greatly influences primary productivity and algal biomass in LNLC environments through changes in the nutrient stocks, and alters the NO3-/DIP ratio, leading to a switch in the nutrient limitation of the phytoplanktonic activity

Nonperturbative improvement and tree-level correction of the quark propagator

We extend an earlier study of the Landau gauge quark propagator in quenched QCD where we used two forms of the O(a)-improved propagator with the Sheikholeslami-Wohlert quark action. In the present study we use the nonperturbative value for the clover coefficient c_sw and mean-field improvement coefficients in our improved quark propagators. We compare this to our earlier results which used the mean-field c_sw and tree-level improvement coefficients for the propagator. We also compare three different implementations of tree-level correction: additive, multiplicative, and hybrid. We show that the hybrid approach is the most robust and reliable and can successfully deal even with strong ultraviolet behavior and zero-crossing of the lattice tree-level expression. We find good agreement between our improved quark propagators when using the appropriate nonperturbative improvement coefficients and hybrid tree-level correction. We also present a simple extrapolation of the quark mass function to the chiral limit.Comment: 12 pages, 18 figures, RevTeX4. Some clarifications and corrections. Final version, to appear in Phys.Rev.

Tuberculosis treatment in a refugee and migrant population: 20 years of experience on the Thai-Burmese border.

Although tuberculosis (TB) is a curable disease, it remains a major global health problem and an important cause of morbidity and mortality among vulnerable populations, including refugees and migrants

From angle-action to Cartesian coordinates: A key transformation for molecular dynamics

The transformation from angle-action variables to Cartesian coordinates is a crucial step of the (semi) classical description of bimolecular collisions and photo-fragmentations. The basic reason is that dynamical conditions corresponding to experiments are ideally generated in angle-action variables whereas the classical equations of motion are ideally solved in Cartesian coordinates by standard numerical approaches. To our knowledge, the previous transformation is available in the literature only for triatomic systems. The goal of the present work is to derive it for polyatomic ones.Comment: 10 pages, 11 figures, submitted to J. Chem. Phy