92 research outputs found
Spectral fingerprints of nonequilibrium dynamics. The case of a Brownian gyrator
The same system can exhibit a completely different dynamical behavior when it evolves in equilibrium conditions or when it is driven out-of-equilibrium by, e.g., connecting some of its components to heat baths kept at different temperatures. Here we concentrate on an analytically solvable and experimentally relevant model of such a system???the so-called Brownian gyrator???a two-dimensional nanomachine that performs a systematic, on average, rotation around the origin under nonequilibrium conditions, while no net rotation takes place under equilibrium ones. On this example, we discuss a question whether it is possible to distinguish between two types of a behavior judging not upon the statistical properties of the trajectories of components but rather upon their respective spectral densities. The latter are widely used to characterize diverse dynamical systems and are routinely calculated from the data using standard built-in packages. From such a perspective, we inquire whether the power spectral densities possess some ???fingerprint??? properties specific to the behavior in nonequilibrium. We show that indeed one can conclusively distinguish between equilibrium and nonequilibrium dynamics by analyzing the cross-correlations between the spectral densities of both components in the short frequency limit, or from the spectral densities of both components evaluated at zero frequency. Our analytical predictions, corroborated by experimental and numerical results, open a new direction for the analysis of a nonequilibrium dynamics
Soil Biochemical Indicators to Monitor the Impact of Microplastics on Soil Functionality in Terrestrial Ecosystems
The present paper introduces soil as a complex system, so a multidisciplinary approach is needed to study not only the composition, abundance, and transport of microplastics (MPs) in terrestrial ecosystems but also soil properties and processes involved in their degradation and/or interaction with soil polyphasic matrix. Despite many researchers focusing their studies on the impact of MPs on the terrestrial ecosystem over the past years, little has been done about the use of biochemical indicators to study their effect on soil functionality
Immobilized inocula of white-rot fungi accelerate both detoxification and organic matter transformation in two-phase dry olive-mill residue
The potential use for agronomic purposes of dry olive-mill residue (DOR), solid waste from the olive oil two-phase extraction process, might be impaired by its phytotoxicity. Although fungal treatments
can detoxify DOR, long times are required for these processes. The objective of this study was to assess whether the addition of immobilized fungal inocula to DOR might improve colonization rates, thus reducing the time necessary for its detoxification and bioconversion. Inocula of Panus tigrinus
CBS 577.79 and Phlebia sp. DABAC 9 immobilized on either chopped maize stalks or polyurethane sponge (PS) led to higher removals of both phenols and phytotoxicity from DOR than free inocula after 4 weeks of incubation. Best dephenolization (85%) was with PS-immobilized Phlebia sp., the
use of which reduced germinability inhibition of Lepidium sativum and Lactuca sativa by 80 and 71.4%, respectively. Regardless of the type of inoculant, a low degree of humification was obtained
CDK1 is a synthetic lethal target for KRAS mutant tumours.
Activating KRAS mutations are found in approximately 20% of human cancers but no RAS-directed therapies are currently available. Here we describe a novel, robust, KRAS synthetic lethal interaction with the cyclin dependent kinase, CDK1. This was discovered using parallel siRNA screens in KRAS mutant and wild type colorectal isogenic tumour cells and subsequently validated in a genetically diverse panel of 26 colorectal and pancreatic tumour cell models. This established that the KRAS/CDK1 synthetic lethality applies in tumour cells with either amino acid position 12 (p.G12V, pG12D, p.G12S) or amino acid position 13 (p.G13D) KRAS mutations and can also be replicated in vivo in a xenograft model using a small molecule CDK1 inhibitor. Mechanistically, CDK1 inhibition caused a reduction in the S-phase fraction of KRAS mutant cells, an effect also characterised by modulation of Rb, a master control of the G1/S checkpoint. Taken together, these observations suggest that the KRAS/CDK1 interaction is a robust synthetic lethal effect worthy of further investigation
CO2 Flux and C Balance due to the Replacement of Bare Soil with Agro-Ecological Service Crops in Mediterranean Environment
Intensive agriculture practices often results in decomposition of organic matter, thus causing soil CO2 emissions. Agro-ecological service crop could be profitably cultivated to improve soil characteristics and reduce CO2 emissions under Mediterranean environment. Two-year field trials were conducted in central Italy. The treatments were three agro-ecological service crops (hairy vetch, oat, and oilseed rape) and a no-service cover. Plant development, soil characteristics, and CO2 emissions were measured. Oat and oilseed rape showed a rapid growth, while hairy vetch started to grow rapidly only after the cold period. Soil CO2 emissions trend was similar among the agro-ecological service crops and tended to decrease during the cold period, then gradually increased until April when warm temperatures were observed. The high soil CO2 emissions and respiration index observed in hairy vetch probably stimulated mineral nutrients, especially nitrogen, to become more available in the soil compared to oat and oilseed rape throughout the decomposition of soil organic matter. These results confirmed that the cultivation of agro-ecological service crops, especially hairy vetch, could represent a suitable strategy for enhancing carbon sequestration and lead to a mitigation of CO2 emissions during the fallow period and could thus contribute to the climate change mitigation
Imaginer, créer, innover
Que nous soyons artistes, mathématiciens, philosophes ou jardiniers « nous sommes tous des créateurs ». C’est par ce premier constat que s’ouvre le dossier « imaginer, créer, innover… » de la revue Sciences Humaines. Comme le rappelait le psychologue Ribot, il y a fort longtemps, tous les hommes possèdent une imagination créatrice qui leur permet de créer et inventer dans les domaines plus disparates. Cela permet d’envisager, dans chaque domaine, la présence de l’imagination créatrice. La pro..
Denis-Constant Martin, L'identité en jeux. Pouvoirs, identifications, mobilisations
La notion d'identité résonne à profusion, aujourd'hui plus que jamais, dans les débats politiques et sociaux. L'institution d'un Ministère de l'Immigration et de l'Identité, évènement advenu non sans bruit, comme les épisodes politiques plus récents, notamment ceux liés à l'expulsion des roms, nous confrontent à la problématique de l'identité. Elle se profile le plus souvent comme nationale, parfois comme l'enveloppe de l'être humain ou politique. Mais au juste, comment faut-il la comprendre ..
Biochemical indicators of quality in cultivated tepetates of the mexican transvolcanic belt.
Los tepetates (tobas volcánicas endurecidas ubicadas en el Eje
Neovolcánico Mexicano) habilitados para la agricultura presentan
un alto grado de degradación debido a malas prácticas
de manejo. El objetivo del trabajo fue definir caracterÃsticas
bioquÃmicas que puedan usarse como indicadores tempranos
del estado de recuperación de tepetates. Durante el periodo
2002-2005 parcelas experimentales cultivadas desde 1986 se
sometieron a tres prácticas agronómicas de manejo: tradicional
(Tt), mejorado (Tm) y orgánico (To). Otras dos parcelas
roturadas en 2002 se trataron con los manejos tradicional
(Rt) y orgánico (Ro). Como referencia se eligieron dos tepetates
sin cultivar (Tv y Td). Se tomaron muestras de suelo
y se determinó: C orgánico (COS), N total (Nt), C y N de
biomasa microbiana (BM), respiración del suelo (RS), mineralización
de N, actividades deshidrogenasa, -glucosidasa,
fosfatasa, ureasa y proteasa, amonificación de la arginina y
diferentes Ãndices metabólicos. Los tepetates sin cultivar, con
escaso contenido en COS y Nt, tuvieron los valores más bajos
de todas las variables bioquÃmicas, las cuales aumentaron
con los años de cultivo, sobre todo con los manejos To y Tm.
Los mayores valores de BM, RS y actividad enzimática se relacionaron
con el aumento del COS en las parcelas con esos
manejos, sugiriendo un incremento de la calidad y fertilidad
de dichos sustratos. Por tanto, el adecuado manejo de los tepetates,
con adición de materia orgánica o fertilizantes con
cobertura de residuos de cosecha, promovió la mejora de sus
propiedades bioquÃmicas. Estas variables se correlacionaron
significativamente, indicando la existencia de estrechas relaciones
entre los procesos bioquÃmicos en los tepetates. Las
variables bioquÃmicas estudiadas fueron indicadores útiles
para evaluar cambios en la calidad de los tepetates cultivados
con diferentes manejos.Tepetates (hardened volcanic tuff located in the Mexican
Transvolcanic Belt) conditioned for agricultural use are
highly degraded due to poor management practices.
The objective of this study was to define biochemical
characteristics that can be used as early indicators of the
state of tepetate recovery. During the period 2002-2005,
experimental plots cultivated since 1986 were subjected to
three agronomic management practices: traditional (Tt),
improved (Tm) and organic (To). Another two plots plowed
in 2002 were treated with traditional (Rt) and organic (Ro)
management. As a reference, two plots of tepetates without
cultivation were selected (Tv and Td). Soil samples were
collected, and the following variables were determined:
soil organic carbon (SOC), total N (Nt), microbial biomass
C and N (BM), soil respiration (RS), N mineralization,
dehydrogenase, -glucosidase, phosphatase, urease and
protease activity, ammonification of arginine, and different
metabolic indexes. The tepetates without cultivation,
containing little SOC and Nt, had the lowest values of all
of the biochemical variables, which increased with years of
cultivation, especially with To and Tm management. The
highest values of BM, RS and enzyme activity were associated
with the increase in SOC in To and Tm plots, suggesting
improved quality and fertility of these substrates. Therefore,
appropriate management of tepetates, with supplements
of organic matter or fertilizers with harvest residue cover,
promoted better biochemical properties. These variables
correlated significantly, indicating the existence of close
relationships among the biochemical processes in the
tepetates. The biochemical variables studied were useful
indicators for assessing changes in quality of the tepetates
cultivated under different management systems.Los autores agradecen a la Unión Europea la financiación del
Proyecto REVOLSO (Programa INCO) y al Ministerio Español
de Educación y Ciencia la ayuda complementaria.Peer reviewe
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