Effects of many-electron jumps in relaxation and conductivity of Coulomb glasses

A numerical study of the energy relaxation and conductivity of the Coulomb glass is presented. The role of many-electron transitions is studied by two complementary methods: a kinetic Monte Carlo algorithm and a master equation in configuration space method. A calculation of the transition rate for two-electron transitions is presented, and the proper extension of this to multi-electron transitions is discussed. It is shown that two-electron transitions are important in bypassing energy barriers which effectively block sequential one-electron transitions. The effect of two-electron transitions is also discussed.Comment: 8 pages, 6 figure

Crossover from diffusive to strongly localized regime in two-dimensional systems

We have studied the conductance distribution function of two-dimensional disordered noninteracting systems in the crossover regime between the diffusive and the localized phases. The distribution is entirely determined by the mean conductance, g, in agreement with the strong version of the single-parameter scaling hypothesis. The distribution seems to change drastically at a critical value very close to one. For conductances larger than this critical value, the distribution is roughly Gaussian while for smaller values it resembles a log-normal distribution. The two distributions match at the critical point with an often appreciable change in behavior. This matching implies a jump in the first derivative of the distribution which does not seem to disappear as system size increases. We have also studied 1/g corrections to the skewness to quantify the deviation of the distribution from a Gaussian function in the diffusive regime.Comment: 4 pages, 4 figure

Optimized auxiliary oscillators for the simulation of general open quantum systems

A method for the systematic construction of few-body damped harmonic oscillator networks accurately reproducing the effect of general bosonic environments in open quantum systems is presented. Under the sole assumptions of a Gaussian environment and regardless of the system coupled to it, an algorithm to determine the parameters of an equivalent set of interacting damped oscillators obeying a Markovian quantum master equation is introduced. By choosing a suitable coupling to the system and minimizing an appropriate distance between the two-time correlation function of this effective bath and that of the target environment, the error induced in the reduced dynamics of the system is brought under rigorous control. The interactions among the effective modes provide remarkable flexibility in replicating non-Markovian effects on the system even with a small number of oscillators, and the resulting Lindblad equation may therefore be integrated at a very reasonable computational cost using standard methods for Markovian problems, even in strongly non-perturbative coupling regimes and at arbitrary temperatures including zero. We apply the method to an exactly solvable problem in order to demonstrate its accuracy, and present a study based on current research in the context of coherent transport in biological aggregates as a more realistic example of its use; performance and versatility are highlighted, and theoretical and numerical advantages over existing methods, as well as possible future improvements, are discussed.Comment: 23 + 9 pages, 11 + 2 figures. No changes from previous version except publication info and updated author affiliation

Lobster (Panulirus argus) captures and their relation with environmental variables obtained by orbital sensors for Cuban waters (1997-2005)

Dados de captura da lagosta Panulirus argus na plataforma cubana foram comparados com concentrações de clorofila (Chl a) e valores de Temperatura de Superfície do Mar (TSM) obtidos pelos sensores Sea Viewing Wide Field of view Sensor (SeaWIFS) e Advanced Very High Resolution Radiometer (AVHRR), respectivamente. Uma análise de correlação cruzada foi realizada entre as anomalias padronizadas das variáveis ambientais (Chl a e TSM) e as anomalias padronizadas de capturas da lagosta para cada zona de pesca no período 1997-2005. Para as águas profundas adjacentes às zonas de pesca não foi observada uma sazonalidade evidente da Chl a. De forma geral, os menores valores de Chl a ocorreram ao sul da Ilha. Na maioria das zonas de pesca, a captura da lagosta apresentou os maiores coeficientes de correlação com valores de Chl a com defasagem de dois e três anos. Já em relação à análise com dados de TSM, os coeficientes de correlação cruzada apresentaram valores significativos apenas a partir de uma defasagem de 1,5 anos para praticamente todas as zonas de pesca. Neste estudo confirma-se que, em águas cubanas, correlações cruzadas significativas entre estas duas variáveis ambientais medidas por satélite e as capturas da lagosta espinhosa ocorrem principalmente durante o ciclo de vida planctônico desta espécie.Chlorophyll concentrations (Chl a) data obtained from the Sea Viewing Wide Field of View Sensor (SeaWIFS) ocean color monthly images, Sea Surface Temperature (SST) pathfinder data obtained from the Advanced Very High Resolution Radiometer (AVHRR) sensors, and lobster (Panulirus argus) captures at the Cuban shelf were examined in order to analyze their spatial and temporal variability. A cross-correlation analysis was made between the standardized anomalies of the environmental variables (Chl a and SST) and the standardized anomalies of lobster captures for each fishery zones for the period between 1997 and 2005. For the deep waters adjacent to the fishing zones it was not observed a clear Chl a seasonality and on average the lowest values occurred south of the Island. It is with the three years lag that Chl a had the greatest numbers of significant correlation coefficients for almost all fishing zones. However, the cross-correlation coefficients with SST showed higher values with 1,5 year lag at all zones. Since the two environmental variables obtained by satellite sensors (SST and Chl a) influence the lobsters mainly during the planktonic life cycle, the cross-correlation with lobster captures begin to show significant indexes with lags of 1.5 years or more

Internal structure of the Late Triassic Central Patagonian batholith at Gastre, southern Argentina: implications for pluton emplacement and the Gastre fault system

The Central Patagonian batholith (CPB) comprises two Late Triassic calcalkaline plutonic suites (the Gastre superunit of 221 ± 2 Ma and the Lipetrén superunit of 215 ± 1 Ma) which have been interpreted as a record of major dextral motion along the transcontinental NW-SE-striking subvertical Gastre fault system in Jurassic times. We performed a detailed study of the internal structure of the CPB through structural and anisotropy of magnetic susceptibility (AMS) techniques. The Gastre superunit reveals a very consistent pattern of NW-SE-striking steeply dipping magmatic foliations. Tectonic fabrics within the CPB are scarce and generally parallel to the magmatic fabrics. The magmatic and solid-state lineations within the CPB are steeply, intermediately, or shallowly plunging. The combination of flattened magmatic and solid-state fabrics with subvertical orientations and with steep to shallow lineations, together with the kinematic indicators in two mylonite belts with suspected CPB protoliths, suggests that the Gastre superunit was emplaced within a sinistral transpressive regime. The shallower stocks of the Lipetrén superunit are more isotropic and have magmatic fabrics associated with magma chamber dynamics. The deformation of the CPB is coaxial with the late Paleozoic deformation in the hosting Calcatapul Formation. The late Paleozoic deformation in the North Patagonian Massif generated widespread NW-SE subvertical fractures which could have aided the emplacement of the CPB. The internal structure of the CPB does not support a model of dextral strike-slip movements on major Jurassic faults.Contiene material suplementario.Facultad de Ciencias Exacta

Internal structure of the Late Triassic Central Patagonian batholith at Gastre, southern Argentina: implications for pluton emplacement and the Gastre fault system

The Central Patagonian batholith (CPB) comprises two Late Triassic calcalkaline plutonic suites (the Gastre superunit of 221 ± 2 Ma and the Lipetrén superunit of 215 ± 1 Ma) which have been interpreted as a record of major dextral motion along the transcontinental NW-SE-striking subvertical Gastre fault system in Jurassic times. We performed a detailed study of the internal structure of the CPB through structural and anisotropy of magnetic susceptibility (AMS) techniques. The Gastre superunit reveals a very consistent pattern of NW-SE-striking steeply dipping magmatic foliations. Tectonic fabrics within the CPB are scarce and generally parallel to the magmatic fabrics. The magmatic and solid-state lineations within the CPB are steeply, intermediately, or shallowly plunging. The combination of flattened magmatic and solid-state fabrics with subvertical orientations and with steep to shallow lineations, together with the kinematic indicators in two mylonite belts with suspected CPB protoliths, suggests that the Gastre superunit was emplaced within a sinistral transpressive regime. The shallower stocks of the Lipetrén superunit are more isotropic and have magmatic fabrics associated with magma chamber dynamics. The deformation of the CPB is coaxial with the late Paleozoic deformation in the hosting Calcatapul Formation. The late Paleozoic deformation in the North Patagonian Massif generated widespread NW-SE subvertical fractures which could have aided the emplacement of the CPB. The internal structure of the CPB does not support a model of dextral strike-slip movements on major Jurassic faults.Contiene material suplementario.Facultad de Ciencias Exacta

Theory and simulation of the nematic zenithal anchoring coefficient

Combining molecular simulation, Onsager theory and the elastic description of nematic liquid crystals, we study the dependence of the nematic liquid crystal elastic constants and the zenithal surface anchoring coefficient on the value of the bulk order parameter

Tailored functionalized magnetic nanoparticles to target breast cancer cells including cancer stem-like cells

Nanotechnology-based approaches hold substantial potential to avoid chemoresistance and minimize side effects. In this work, we have used biocompatible iron oxide magnetic nanoparticles (MNPs) called MF66 and functionalized with the antineoplastic drug doxorubicin (DOX) against MDA-MB-231 cells. Electrostatically functionalized MNPs showed effective uptake and DOX linked to MNPs was more efficiently retained inside the cells than free DOX, leading to cell inactivation by mitotic catastrophe, senescence and apoptosis. Both effects, uptake and cytotoxicity, were demonstrated by different assays and videomicroscopy techniques. Likewise, covalently functionalized MNPs using three different linkers—disulfide (DOX-S-S-Pyr, called MF66-S-S-DOX), imine (DOX-I-Mal, called MF66-I-DOX) or both (DOX-I-S-S-Pyr, called MF66-S-S-I-DOX)—were also analysed. The highest cell death was detected using a linker sensitive to both pH and reducing environment (DOX-I-S-S-Pyr). The greatest success of this study was to detect also their activity against breast cancer stem-like cells (CSC) from MDA-MB-231 and primary breast cancer cells derived from a patient with a similar genetic profile (triple-negative breast cancer). In summary, these nanoformulations are promising tools as therapeutic agent vehicles, due to their ability to produce efficient internalization, drug delivery, and cancer cell inactivation, even in cancer stem-like cells (CSCs) from patientsThis research was funded by the European Seventh Framework Program (grant agreement number 262943); the European Union’s Horizon 2020 research and innovation programme (grant agreement number 685795); Ministerio de Economía y Competitividad, Spain (grants CTQ2016-78454-C2-2-R, BIO2016-77367-C2-1-R and SAF2017-87305-R); Basque Government Elkartek KK- 2017/00008; Comunidad de Madrid (IND2017/IND-7809; S2017/BMD-3867 RENIM-CM and S2018/NMT-4321 NANOMAGCOST-CM); NIHR Manchester Biomedical Research Centre (IS-BRC-1215-20007) and Breast Cancer Now (MAN-Q2); co-financed by European Structural Cancers 2020, 12, 1397 17 of 19 and Investment Fund, Asociación Española Contra el Cáncer (Singulares 2014) and IMDEA Nanociencia. CIC biomaGUNE acknowledges Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency (Grant MDM-2017-0720). IMDEA Nanociencia acknowledges support from the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (MINECO, Grant SEV-2016-0686