Optimization of the ionization time of an atom with tailored laser pulses: a theoretical study

How fast can a laser pulse ionize an atom? We address this question by considering pulses that carry a fixed time-integrated energy per-area, and finding those that achieve the double requirement of maximizing the ionization that they induce, while having the shortest duration. We formulate this double-objective quantum optimal control problem by making use of the Pareto approach to multi-objetive optimization, and the differential evolution genetic algorithm. The goal is to find out how much a precise time-profiling of ultra-fast, large-bandwidth pulses may speed up the ionization process with respect to simple-shape pulses. We work on a simple one-dimensional model of hydrogen-like atoms (the P\"oschl-Teller potential), that allows to tune the number of bound states that play a role in the ionization dynamics. We show how the detailed shape of the pulse accelerates the ionization process, and how the presence or absence of bound states influences the velocity of the process

On the use of Neumann's principle for the calculation of the polarizability tensor of nanostructures

The polarizability measures how the system responds to an applied electrical field. Computationally, there are many different ways to evaluate this tensorial quantity, some of which rely on the explicit use of the external perturbation and require several individual calculations to obtain the full tensor. In this work, we present some considerations about symmetry that allow us to take full advantage of Neumann's principle and decrease the number of calculations required by these methods. We illustrate the approach with two examples, the use of the symmetries in real space and in spin space in the calculation of the electrical or the spin response.Comment: 7 pages, 5 figures, accepted for publication in the Journal of Nanoscience and Nanotechnolog

Taxonomic and Serological Researches on the Phymaturus patagonicus Complex

Five subspecies of Phymaturus from Argentine Patagonia are identified: P. patagonicus patagonicus Koslowsky, P. patagonicus indistinctus subsp. nov., both from Chubut, P. patagonicus somuncurensis, subsp. nov. from Rio Negro, P. patagonicus zapaiensis subsp. nov. from Neuquén, and P. patagonicus payuniae subsp. nov. from Southern Mendoza. Their morphological and ecological features are described according to their widespread but isolated distribution. Quantitative immunological analyses emphasize the close affinities of the 5 proposed subspecies and their more distant relationships to P. palluma which is sympatric with P. patagonicus in Mendoza and Neuquén.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Muse

Selection and acclimatization of strains of edible mycorrhizal fungi for improved field persistence

info:eu-repo/semantics/publishedVersio

Taxonomic and Serological Researches on the Phymaturus patagonicus Complex

Five subspecies of Phymaturus from Argentine Patagonia are identified: P. patagonicus patagonicus Koslowsky, P. patagonicus indistinctus subsp. nov., both from Chubut, P. patagonicus somuncurensis, subsp. nov. from Rio Negro, P. patagonicus zapaiensis subsp. nov. from Neuquén, and P. patagonicus payuniae subsp. nov. from Southern Mendoza. Their morphological and ecological features are described according to their widespread but isolated distribution. Quantitative immunological analyses emphasize the close affinities of the 5 proposed subspecies and their more distant relationships to P. palluma which is sympatric with P. patagonicus in Mendoza and Neuquén.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Muse

Bringing trust and transparency to the opaque world of waste management with blockchain: a Polkadot parathread application

Scott, Ian and de Castro Neto, Miguel and Pinheiro, Flavio L., Bringing Trust and Transparency to the Opaque World of Waste Management with Blockchain: A Polkadot Parathread Application (March 22, 2021). Available at SSRN: https://ssrn.com/abstract=3825072 or http://dx.doi.org/10.2139/ssrn.3825072The majority of countries are currently struggling to achieve sustainable levels of recycling and waste treatment, particularly relating to household waste, and this area is in urgent need of new solutions. In general, the waste management sector has struggled with low consumer trust, fraud, manipulation, significant manual processes, and low levels of information and control. Here we propose a hybrid blockchain solution called a Polkadot parachain. Polkadot is a blockchain technology that allows for the development of a network of blockchains, each called a parachain that can be customised to the business needs of a given application. This solution provides the cost benefits, scalability, and control of a permissioned blockchain while providing the security, verifiability, and trust of a public blockchain. The solution combines three typically separate blockchain use cases: supply chain tracking, incentivisation through a payment system, and gamification to achieve a complete solution for waste management. We provide a detailed discussion on the design of this blockchain solution with the use of blockchain functionality assessed against the criteria and development approaches found in the literature. Finally, we demonstrate how such a blockchain can be implemented with the Substrate blockchain development framework and detail a pilot project where this system will be implemented.publishersversionpublishe

Growth dynamic of dual culture systems comprising ectomycorrhizal fungi and mycorrhiza helper bacteria

Ectomycorrhizal fungi are ubiquitous root symbionts that associate with the majority of forest trees and often have a crucial role on plant survival and growth in impoverished soils. Within the vast community of soil microorganisms, the mycorrhiza helper bacteria (MHB) are recognizably one of the groups that most directly affect fungal growth and mycorrhiza establishment. Although their positive effect on the mycorrhizal partnership has been previously reported, the specificity of such association is high and the dynamics not yet fully understood. Many studies evaluated the impact of bacteria on fungal growth but the reciprocal has received little attention. The present study aimed to evaluate the growth dynamics of co-culturing fungi and bacteria, under both perspectives. Bacillus pumilus was chosen for its capability to promote the growth of Suillus granulatus in a dual culture system with a low nutrient medium. To assess the impact of fungal exudates on bacterial growth, different quantities of fungal culture medium were added to MMN medium containing a Bacillus pumilus inoculum and bacterial growth was monitored. To evaluate the influence of Bacillus pumilus on fungal growth, an experiment was setup where the bacterium was added at two different phases of fungal growth, lag phase and exponential phase. A control without bacteria was also performed. Bacterial growth was monitored through OD readings and fungal growth was assessed through dry weight and ergosterol content. The experience was held for 33 days, with sampling every three days. Triplicates for each treatment were performed. Results from the first experiment showed that fungal exudates influenced the growth of bacteria with a pronounced extension of the lag phase. In the second experiment, fungal growth was completely inhibited when bacteria was added at the fungal lag phase. A different outcome was observed when the bacterium was added in the exponential phase. Results suggest that the regulation of the concentration at which the bacterium is present may be a key factor to optimization of the use of bacteria as MHB

octopus: a first-principles tool for excited electron–ion dynamics

We present a computer package aimed at the simulation of the electron–ion dynamics of finite systems, both in one and three dimensions, under the influence of time-dependent electromagnetic fields. The electronic degrees of freedom are treated quantum mechanically within the time-dependent Kohn–Sham formalism, while the ions are handled classically. All quantities are expanded in a regular mesh in real space, and the simulations are performed in real time. Although not optimized for that purpose, the program is also able to obtain static properties like ground-state geometries, or static polarizabilities. The method employed proved quite reliable and general, and has been successfully used to calculate linear and non-linear absorption spectra, harmonic spectra, laser induced fragmentation, etc. of a variety of systems, from small clusters to medium sized quantum dots.This work was partially supported by the RTN program of the European Union NANOPHASE (contract HPRN-CT-2000-00167), DGESIC (PB98-0345) and JCyL (VA28/99). G.B. acknowledges support by the U.S. Department of Energy under Contract No. E-FG-06-90ER-41132.Peer reviewe

The genomic environment around the Aromatase gene: evolutionary insights

BACKGROUND: The cytochrome P450 aromatase (CYP19), catalyses the aromatisation of androgens to estrogens, a key mechanism in vertebrate reproductive physiology. A current evolutionary hypothesis suggests that CYP19 gene arose at the origin of vertebrates, given that it has not been found outside this clade. The human CYP19 gene is located in one of the proposed MHC-paralogon regions (HSA15q). At present it is unclear whether this genomic location is ancestral (which would suggest an invertebrate origin for CYP19) or derived (genomic location with no evolutionary meaning). The distinction between these possibilities should help to clarify the timing of the CYP19 emergence and which taxa should be investigated. RESULTS: Here we determine the "genomic environment" around CYP19 in three vertebrate species Homo sapiens, Tetraodon nigroviridis and Xenopus tropicalis. Paralogy studies and phylogenetic analysis of six gene families suggests that the CYP19 gene region was structured through "en bloc" genomic duplication (as part of the MHC-paralogon formation). Four gene families have specifically duplicated in the vertebrate lineage. Moreover, the mapping location of the different paralogues is consistent with a model of "en bloc" duplication. Furthermore, we also determine that this region has retained the same gene content since the divergence of Actinopterygii and Tetrapods. A single inversion in gene order has taken place, probably in the mammalian lineage. Finally, we describe the first invertebrate CYP19 sequence, from Branchiostoma floridae. CONCLUSION: Contrary to previous suggestions, our data indicates an invertebrate origin for the aromatase gene, given the striking conservation pattern in both gene order and gene content, and the presence of aromatase in amphioxus. We propose that CYP19 duplicated in the vertebrate lineage to yield four paralogues, followed by the subsequent loss of all but one gene in vertebrate evolution. Finally, we suggest that agnathans and lophotrocozoan protostomes should be investigated for the presence of aromatase

Mitochondrial Quality Control and Parkinson’s Disease: A Pathway Unfolds

Recent findings from genetic studies suggest that defective mitochondrial quality control may play an important role in the development of Parkinson's disease (PD). Such defects may result in the impairment of neuronal mitochondria, which leads to both synaptic dysfunction and cell death and results in neurodegeneration. Here, we review state-of-the-art knowledge of how pathways affecting mitochondrial quality control might contribute to PD, with a particular emphasis on the molecular mechanisms employed by PTEN-induced putative kinase 1 (PINK1), HtrA2 and Parkin to regulate mitochondrial quality control