Time-dependent numerical renormalization group method for multiple quenches: towards exact results for the long time limit of thermodynamic observables and spectral functions

We develop an alternative time-dependent numerical renormalization group (TDNRG) formalism for multiple quenches and implement it to study the response of a quantum impurity system to a general pulse. Within this approach, we reduce the contribution of the NRG approximation to numerical errors in the time evolution of observables by a formulation that avoids the use of the generalized overlap matrix elements in our previous multiple-quench TDNRG formalism [Nghiem {\em et al.,} Phys. Rev. B {\bf 89}, 075118 (2014); Phys. Rev. B {\bf 90}, 035129 (2014)]. We demonstrate that the formalism yields a smaller cumulative error in the trace of the projected density matrix as a function of time and a smaller discontinuity of local observables between quenches than in our previous approach. Moreover, by increasing the switch-on time, the time between the first and last quench of the discretized pulse, the long-time limit of observables systematically converges to its expected value in the final state, i.e., the more adiabatic the switching, the more accurately is the long-time limit recovered. The present formalism can be straightforwardly extended to infinite switch-on times. We show that this yields highly accurate results for the long-time limit of both thermodynamic observables and spectral functions, and overcomes the significant errors within the single quench formalism [Anders {\em et al.}, Phys. Rev. Lett. {\bf 95}, 196801 (2005); Nghiem {\em et al.}, Phys. Rev. Lett. {\bf 119}, 156601 (2017)]. This improvement provides a first step towards an accurate description of nonequilibrium steady states of quantum impurity systems, e.g., within the scattering states NRG approach [Anders, Phys. Rev. Lett. {\bf 101}, 066804 (2008)].Comment: 15 pages and 10 figures; Additional figures and references added; typos fixed; references fixe

Combined Global and Local Search for the Falsification of Hybrid Systems

In this paper we solve the problem of finding a trajectory that shows that a given hybrid dynamical system with deterministic evolution leaves a given set of states considered to be safe. The algorithm combines local with global search for achieving both efficiency and global convergence. In local search, it exploits derivatives for efficient computation. Unlike other methods for falsification of hybrid systems with deterministic evolution, we do not restrict our search to trajectories of a certain bounded length but search for error trajectories of arbitrary length

Functionalized Materials as a Versatile Platform for Enzyme Immobilization in Wastewater Treatment

Purpose of Review Untreated wastewater discharge can significantly and negatively impact the state of the environment. Rapid industrialization and economic development have directly contributed to land and water pollution resulting from the application of many chemicals such as organic dyes, pharmaceuticals, and industrial reagents. The removal of these chemicals before effluent discharge is crucial for environmental protection. This review aims to explore the importance of functionalized materials in the preparation of biocatalytic systems and consider their application in eliminating water pollutants. Recent Findings Wastewater treatment methods can be classified into three groups: (i) chemical (e.g., chemical oxidation and ozonation), (ii) physical (e.g., membrane separation and ion exchange), and (iii) biological processes. Biological treatment is the most widely used method due to its cost-effectiveness and eco-friendliness. In particular, the use of immobilized enzymes has recently become more attractive as a result of scientific progress in advanced material synthesis. The selection of an appropriate support plays an important role in the preparation of such biologically active systems. Recent studies have demonstrated the use of various materials for enzyme immobilization in the purification of water. Summary This review identifies and discusses different biocatalytic systems used in the enzymatic degradation of various water pollutants. Materials functionalized by specific groups can serve as good support matrices for enzyme immobilization, providing chemical and thermal stability to support catalytic reactions. Enzymatic biocatalysis converts the pollutants into simpler products, which are usually less toxic than their parents. Due to immobilization, the enzyme can be used over multiple cycles to reduce the cost of wastewater treatment. Future studies in this field should focus on developing new platforms for enzyme immobilization in order to improve degradation efficiency

A Regional Decision Support Scheme for Pest Risk Analysis in Southeast Asia

A key justification to support plant health regulations is the ability of quarantine services to conduct pest risk analyses (PRA). Despite the supranational nature of biological invasions and the close proximity and connectivity of Southeast Asian countries, PRAs are conducted at the national level. Furthermore, some countries have limited experience in the development of PRAs, which may result in inadequate phytosanitary responses that put their plant resources at risk to pests vectored via international trade. We review existing decision support schemes for PRAs and, following international standards for phytosanitary measures, propose new methods that adapt existing practices to suit the unique characteristics of Southeast Asia. Using a formal written expert elicitation survey, a panel of regional scientific experts was asked to identify and rate unique traits of Southeast Asia with respect to PRA. Subsequently, an expert elicitation workshop with plant protection officials was conducted to verify the potential applicability of the developed methods. Rich biodiversity, shortage of trained personnel, social vulnerability, tropical climate, agriculture-dependent economies, high rates of land-use change, and difficulties in implementing risk management options were identified as challenging Southeast Asian traits. The developed methods emphasize local Southeast Asian conditions and could help support authorities responsible for carrying out PRAs within the region. These methods could also facilitate the creation of other PRA schemes in low- and middle-income tropical countries

Significance of the presence of antibiotics on the microbial consortium in wastewater - The case of nitrofurantoin and furazolidone.

Antibiotics in wastewater leads to migration of pollutants and disrupts natural processes of mineralization of organic matter. In order to understand the mechanism of this, research was undertaken on the influence of nitrofurantoin (NFT) and furazolidone (FZD), on the behaviour of a consortium of microorganisms present in a model wastewater in a bioreactor. Our study confirmed biodegradation of the antibiotics by the microbial consortium, with the degradation efficiency within 10 days of 65% for FZD, but only 20% for NFT. The kinetic study proved that the presence of analysed antibiotics had no adverse effect on the microbes, but the consortium behaviour differ significantly with the NFT reducing the consumption of organic carbon in wastewater and increasing the production of extracellular biopolymeric and volatile organic compounds, and the FZD reducing assimilation of other carbon sources to a less extent, at the expense of cellular focus on biodegradation of this antibiotic

Conséquences de l’évolution de l’occupation des sols sur les lacs et les rivières d’un bassin versant de moyenne montagne: application au bassin versant de l’Ain (France)

The Ain river – tributary of the Rhone, is distinguished by a geological and geomorphological duality splitting it into two very clear parts: the mountainous (karstic-jura mountains) and the low alluvial valley of the Ain river, characterized by agricultural land use. The geographical boundary between the two zones is the dam of Vouglans (3rd water reserve of France). These geological differences give rise to two types of reserves: karstic reserves at the top of the watershed and an alluvial water table enclosed in the quaternary alluvium at the bottom. The last thirty years have been marked by the massive exodus of the rural populations of the Haut, which maintained a pastoral activity for the valleys holding most of the industries. A renewal of pastoral areas by mainly coniferous and deciduous forests, particularly in the upper part of the catchment area (Jura), reflects this phenomenon of exodus. This process was accompanied by an increase in the input of organic matter and marked deoxygenation of the deep (hypolimnion) levels of the water bodies, mostly located at the top. This physico-chemical manifestation is felt at the bottom in rivers and more particularly in the river Ain, one of the main tributaries of the Rhone. The management of water resources has been subjected to this geological and economic duality, giving rise to a SWMM (Scheme for Water Management and Management) based on the alluvial plain in the lower part of the watershed and the installation of numerous contracts of rivers on the affluent of the Ain in addition to the SWMM. One of the priority concerns of managers is the assessment of the extent of deoxygenation recorded in the plans to the rivers and especially its consequences on the lower rivers. The results of measurements and models applied show that the phenomenon is not very noticeable upstream and downstream of the Vouglans dam. Predictive simulations incorporating the GIEC recommendations (optimistic and pessimistic scenario) do not show a particular trend for 2050.The Ain river – tributary of the Rhone, is distinguished by a geological and geomorphological duality splitting it into two very clear parts: the mountainous (karstic-jura mountains) and the low alluvial valley of the Ain river, characterized by agricultural land use. The geographical boundary between the two zones is the dam of Vouglans (3rd water reserve of France). These geological differences give rise to two types of reserves: karstic reserves at the top of the watershed and an alluvial water table enclosed in the quaternary alluvium at the bottom. The last thirty years have been marked by the massive exodus of the rural populations of the Haut, which maintained a pastoral activity for the valleys holding most of the industries. A renewal of pastoral areas by mainly coniferous and deciduous forests, particularly in the upper part of the catchment area (Jura), reflects this phenomenon of exodus. This process was accompanied by an increase in the input of organic matter and marked deoxygenation of the deep (hypolimnion) levels of the water bodies, mostly located at the top. This physico-chemical manifestation is felt at the bottom in rivers and more particularly in the river Ain, one of the main tributaries of the Rhone. The management of water resources has been subjected to this geological and economic duality, giving rise to a SWMM (Scheme for Water Management and Management) based on the alluvial plain in the lower part of the watershed and the installation of numerous contracts of rivers on the affluent of the Ain in addition to the SWMM. One of the priority concerns of managers is the assessment of the extent of deoxygenation recorded in the plans to the rivers and especially its consequences on the lower rivers. The results of measurements and models applied show that the phenomenon is not very noticeable upstream and downstream of the Vouglans dam. Predictive simulations incorporating the GIEC recommendations (optimistic and pessimistic scenario) do not show a particular trend for 2050

Polarimetric scattering from layered media with multiple species of scatterers

Geophysical media are usually heterogeneous and contain multiple species of scatterers. In this paper a model is presented to calculate effective permittivities and polarimetric backscattering coefficients of multispecies-layered media. The same physical description is consistently used in the derivation of both permittivities and scattering coefficients. The strong permittivity fluctuation theory is extended to account for the multiple species of scatterers with a general ellipsoidal shape whose orientations are randomly distributed. Under the distorted Born approximation, polarimetric scattering coefficients are obtained. These calculations are applicable to the special cases of spheroidal and spherical scatterers. The model is used to study effects of scatterer shapes and multispecies mixtures on polarimetric signatures of heterogeneous media. The multispecies model accounts for moisture content in scattering media such as snowpack in an ice sheet. The results indicate a high sensitivity of backscatter to moisture with a stronger dependence for drier snow and ice grain size is important to the backscatter. For frost-covered saline ice, model results for bare ice are compared with measured data at C band and then the frost flower formation is simulated with a layer of fanlike ice crystals including brine infiltration over a rough interface. The results with the frost cover suggest a significant increase in scattering coefficients and a polarimetric signature closer to isotropic characteristics compared to the thin saline ice case