Contribution des parties aériennes et souterraines des plantes à la matière organique des sols évaluée à partir de la dynamique des marqueurs des cutines et des subérines

In cropland soils, plant residues and microorganisms are the main sources of organic matter. Soil organic matter (SOM) represents an important pool of carbon. Mineralisation of soil organic carbon is an important issue and studies on soil organic matter degradation and/or stabilisation showed contrasted results when changing soil management. However degradation and stabilisation processes turning the fresh plant material into stabilised soil organic matter remain unclear. One major question concerns the contribution of above ground versus below ground plant residues to SOM. To improve knowledge on degradation and stabilization processes in the soil matrix, we studied the fate of makers of cutin and suberin in the INRA experimental field of “les closeaux”. These macromolecules are present respectively in the above ground and the below ground tissues of higher plants and are constituted of specific monomers. The experimental field of les Closeaux consists of a twelve year chronosequence of maize crop replacing the previous wheat crop. The two cropping plants have two different 13C contents: wheat, a C3 plant (13C ≈ -27 ‰) and maize, a C4 plant (13C ≈ -12 ‰). The natural 13C labelling of biopolyester monomers in the different parts of the two plants (leaves, stems and roots) and in soil was measured. The analysis of biopolyester monomers in the different parts of the two plants and the soil allows following their incorporation into the SOM pool. In addition, soil under wheat and after 9 years of maize cropping was analysed in depth.Comparison of depolymerisation methods showed that saponification followed by direct silylation is the most accurate for the analysis of biopolyester monomers in plants and their contribution to soil bound lipids. In plants, diacids and mid chain hydroxy acids are specifics for below and above ground tissues. Monomer inputs from above ground polyesters represented more than 80% of total monomers returned into the soils for the two plants studied. Despite of the high shoot polyester inputs, in soil, concentration in cutin specific monomers is equivalent to root suberized tissues monomers and indicate a selective degradation and stabilisation of polymers in soils. At molecular level single monomer are not degraded in the same way implying that a macromolecule such as cutin or suberin is not heterogeneously degraded by microorganisms. The contrasting behaviours of root suberized tissues and cutins from shoots in soils might be explained by different physical and chemical processes leading to selective degradation and stabilization of these tissues. Incorporation rates of cutin and suberin markers display contrasted behaviour among the two biopolyesters. Cutin monomers deriving from maize plant are poorly incorporated into SOM inferring that cutins bring to the soil is promptly degraded and that monomers released from soils samples arise from old C3 vegetation. Soil suberin monomers incorporation rates underlined the higher contribution of maize roots biomass when compared to wheat root. Stabilisation of suberin marker incorporation after 6 years of maize cropping suggests at least two kinetic pools of degradation and stabilisation. With depth, 9 years of maize cropping influenced cutin and suberin concentrations. The higher maize roots density when compared to wheat roots leads to high incorporation of suberin monomers deriving from maize root in all the soil profile. The lower concentration of cutin markers in depth in the soil under maize when compared to soil under wheat implyied degradation of cutins, althought we supposed they were stabilized in soil depth.Les matières organiques des sols (MOS) représentent un réservoir majeur de stockage de carbone et elles sont étroitement associées aux propriétés physiques et physicochimiques du sol. Cependant, certaines pratiques agricoles comme le labour ont pour effet de minéraliser les MOS, aussi de nouvelles pratiques culturales ont été mises en place, dont le non labour ou le retour au sol des résidus de cultures. Cependant, des résultats très contrastés ont été décrits quant à l’augmentation des MOS par changement de pratiques culturales. De plus, la biomasse racinaire contribue plus aux MOS que les parties aériennes, dans un système où les résidus de cultures sont retournés au sol, alors que la proportion de MO contenue dans les racines est plus faible que celle provenant des parties aériennes.Afin de mieux comprendre les processus de dégradation et/ou de stabilisation de la matière organique dans les sols, nous avons choisi d’étudier deux biopolymères présents dans les parties aériennes et souterraines des plantes : les cutines et les subérines. Ces deux biopolyesters sont composés de monomères spécifiques. Nous avons tout d’abord mené une étude comparative des méthodes de dépolymérisation utilisées pour étudier ces biopolymères et montré que la méthode la plus adaptée était l’hydrolyse basique suivie de silylation. Nous avons ensuite appliqué cette méthode à des sols. Pour suivre la dynamique de ces biopolyesters, nous avons choisi le site expérimental de l’INRA « des Closeaux », qui comporte une chronoséquence blé/maïs, mise en place en 1993. Ces deux plantes ont été choisies en raison de leur teneur distincte en 13C due à la différence de leur voie biosynthétique : le blé est une plante en C3 (13C ≈ -28‰) alors que le maïs est une plante en C4 (13C ≈ -12‰). Les MOS possédant une signature isotopique proche de celle de la végétation, ce dispositif permet de suivre in situ, l’incorporation de la MO provenant du maïs à la MOS. Nous avons comparé la contribution des monomères de cutine et subérine dans des horizons de surface d’un sol initialement sous blé et après 6 et 12 ans de culture de maïs, puis nous nous sommes intéressés au devenir de ces biopolymères en profondeur après 9 ans de culture de maïs. La proportion de cutines et de subérines incorporées dans les sols a été établie afin de déterminer les processus conduisant à la dégradation et/ou stabilisation de la biomasse aérienne vs la biomasse racinaire. Les cutines présentes dans les parties aériennes des plantes ne sont pas ou peu incorporées dans les sols, ce qui indique que les cutines déjà présentes dans les sols sont stabilisées et que les cutines de maïs sont en grande partie dégradées au fur et à mesure de leur incorporation aux sols. Pour les subérines contenues dans les racines, nous avons mesuré un taux d’incorporation aux MOS de 20% à 60% selon le monomère après 6 ans de culture de maïs suivi d’une stabilisation entre 6 et 12 ans de culture de maïs. Pour les subérines, il semble donc y avoir plusieurs compartiments cinétiques : un compartiment stable et un compartiment qui se renouvelle rapidement. De plus, la distribution des marqueurs de cutines et de subérines est très différente dans les plantes et dans les sols, indiquant que les biopolymères ne sont pas dégradés de manière homogène. Enfin, en profondeur, les résultats sur les concentrations et la signature isotopique des marqueurs des racines montrent que les racines de maïs influencent la dynamique des MOS sur tout le profil étudié. En effet, on assiste à une augmentation des monomères spécifiques de subérines en profondeur, due au profil racinaire dense du maïs par rapport à celui du blé. Par contre, la diminution de la contribution des cutines en profondeur indique que le changement de culture de blé à maïs a induit une dégradation de cutines, dont on pouvait penser qu’elles étaient stabilisées

Simulació multiagent de la Girona medieval emprant SDLPS

Català: Construcció i validació d'un Model de simulació multiagent i amb un autòmat cel·lular basat en una ciutat i parametritzable com la ciutat de Girona a l'època medieval

Influencia del control interno en las contrataciones públicas del Gobierno Regional de Tacna en el periodo 2021

La investigación se basó en determinar la influencia del control interno en las contrataciones públicas del GRT, 2021. La metodología utilizada fue bajo el enfoque cuantitativo, descriptivo, correlacional, no experimental y transversal; la muestra fue censal con 28 trabajadores, se usó el cuestionario que fueron evaluados por el alfa de cronbach y resultaron valores de 0.902 y 0.929 las cuales muestran que existe un alto nivel de fiabilidad con los resultados obtenidos; además se consideró la entrevista que fue realizada al Subgerente de Abastecimiento del GRT. Como resultados de la encuesta se halló que existe influencia del control interno con la programación y actos preparatorios (p-valor = 0.000 < 0.05), procesos de selección (p-valor = 0.000 < 0.05) y la ejecución contractual (p-valor = 0.008 < 0.05). Concluyendo que los elementos estudiados si tienen influencia significativa, esta relación es buena (CCRS= 0.777), con una significancia estadística de p-valor = 0.000, siendo inferior a 0.05.Escuela de Postgrad

Cover crop root contributions to soil carbon in a no-till corn bioenergy cropping system

Crop residues are potential biofuel feedstocks, but residue removal may reduce soil carbon (C). The inclusion of a cover crop in a corn bioenergy system could provide additional biomass, mitigating the negative effects of residue removal by adding to stable soil C pools. In a no-till continuous corn bioenergy system in the northern US Corn Belt, we used 13CO2 pulse labeling to trace plant C from a winter rye (Secale cereale) cover crop into different soil C pools for 2 years following rye cover crop termination. Corn stover left as residue (30% of total stover) contributed 66, corn roots 57, rye shoots 61, rye roots 50, and rye rhizodeposits 25 g C m−2 to soil. Five months following cover crop termination, belowground cover crop inputs were three times more likely to remain in soil C pools than were aboveground inputs, and much of the root-derived C was in mineral-associated soil fractions. After 2 years, both above- and belowground inputs had declined substantially, indicating that the majority of both root and shoot inputs are eventually mineralized. Our results underscore the importance of cover crop roots vs. shoots and the importance of cover crop rhizodeposition (33% of total belowground cover crop C inputs) as a source of soil C. However, the eventual loss of most cover crop C from these soils indicates that cover crops will likely need to be included every year in rotations to accumulate soil C

Monoaminergic and histaminergic strategies and treatments in brain diseases

The monoaminergic systems are the target of several drugs for the treatment of mood, motor and cognitive disorders as well as neurological conditions. In most cases, advances have occurred through serendipity, except for Parkinson's disease where the pathophysiology led almost immediately to the introduction of dopamine restoring agents. Extensive neuropharmacological studies first showed that the primary target of antipsychotics, antidepressants, and anxiolytic drugs were specific components of the monoaminergic systems. Later, some dramatic side effects associated with older medicines were shown to disappear with new chemical compounds targeting the origin of the therapeutic benefit more specifically. The increased knowledge regarding the function and interaction of the monoaminergic systems in the brain resulting from in vivo neurochemical and neurophysiological studies indicated new monoaminergic targets that could achieve the efficacy of the older medicines with fewer side-effects. Yet, this accumulated knowledge regarding monoamines did not produce valuable strategies for diseases where no monoaminergic drug has been shown to be effective. Here, we emphasize the new therapeutic and monoaminergic-based strategies for the treatment of psychiatric diseases. We will consider three main groups of diseases, based on the evidence of monoamines involvement (schizophrenia, depression, obesity), the identification of monoamines in the diseases processes (Parkinson's disease, addiction) and the prospect of the involvement of monoaminergic mechanisms (epilepsy, Alzheimer's disease, stroke). In most cases, the clinically available monoaminergic drugs induce widespread modifications of amine tone or excitability through neurobiological networks and exemplify the overlap between therapeutic approaches to psychiatric and neurological conditions. More recent developments that have resulted in improved drug specificity and responses will be discussed in this review.peer-reviewe

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Combined search for the quarks of a sequential fourth generation

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy

A search for new physics is performed in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state. The analysis is based on a data sample corresponding to an integrated luminosity of 4.98 inverse femtobarns produced in pp collisions at a center-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of 140 increase in integrated luminosity over previously published results. The observed yields agree with the standard model predictions and thus no evidence for new physics is found. The observations are used to set upper limits on possible new physics contributions and to constrain supersymmetric models. To facilitate the interpretation of the data in a broader range of new physics scenarios, information on the event selection, detector response, and efficiencies is provided.Comment: Published in Physical Review Letter

Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

Measurement of the Z/gamma* + b-jet cross section in pp collisions at 7 TeV

The production of b jets in association with a Z/gamma* boson is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV and recorded by the CMS detector. The inclusive cross section for Z/gamma* + b-jet production is measured in a sample corresponding to an integrated luminosity of 2.2 inverse femtobarns. The Z/gamma* + b-jet cross section with Z/gamma* to ll (where ll = ee or mu mu) for events with the invariant mass 60 < M(ll) < 120 GeV, at least one b jet at the hadron level with pT > 25 GeV and abs(eta) < 2.1, and a separation between the leptons and the jets of Delta R > 0.5 is found to be 5.84 +/- 0.08 (stat.) +/- 0.72 (syst.) +(0.25)/-(0.55) (theory) pb. The kinematic properties of the events are also studied and found to be in agreement with the predictions made by the MadGraph event generator with the parton shower and the hadronisation performed by PYTHIA.Comment: Submitted to the Journal of High Energy Physic