Diferencijalni udarni presjeci za rašprsenje elektrona atomima iterbija

Electron scattering by ytterbium atom is studied at energies 10, 20, 40, 60 and 80 eV, by applying a parameter-free complex optical potential. The real part of the complex optical potential includes the static potential Vst(r), the polarization potential Vpol(r) that consists of the short range correlation and long-range polarization effects and Vex(r) term consisting of electron exchange interaction which is modelled by assuming the electron charge cloud as a free electron gas. The loss of flux into the inelastic channels is included via a phenomenological absorption potential. Our results are compared with the recent experimental measurements.Proučavamo raspršenje elektrona na enegijama 10, 20, 40, 60 i 80 eV primjenom bezparametarskog kompleksnog optičkog potencijala. Realni dio optičkog potencijala uključuje statički potencijal Vst(r), polarizacijski potencijal Vpol(r) koji se sastoji od kratko-dosežnih korelacija i dugo-dosežnih polarizacijskih efekata i član Vex(r) koji se sastoji od elektronskog međudjelovanja izmjene, a izražen je pretpostavivši oblak elektronskog naboja kao slobodan elektronski plin. Gubitak toka u neelastične kanale uključuje se preko fenomenološkog apsorpcijskog potencijala. Postignuti ishodi uspoređuju se s nedavnim eksperimentalnim podacima

Evolutionary Approaches to Optimization Problems in Chimera Topologies

Chimera graphs define the topology of one of the first commercially available quantum computers. A variety of optimization problems have been mapped to this topology to evaluate the behavior of quantum enhanced optimization heuristics in relation to other optimizers, being able to efficiently solve problems classically to use them as benchmarks for quantum machines. In this paper we investigate for the first time the use of Evolutionary Algorithms (EAs) on Ising spin glass instances defined on the Chimera topology. Three genetic algorithms (GAs) and three estimation of distribution algorithms (EDAs) are evaluated over $1000$ hard instances of the Ising spin glass constructed from Sidon sets. We focus on determining whether the information about the topology of the graph can be used to improve the results of EAs and on identifying the characteristics of the Ising instances that influence the success rate of GAs and EDAs.Comment: 8 pages, 5 figures, 3 table

Ukupni (elastični i neelastični) udarni presjeci raspršenja elektrona na molekulama N2O, CF4, NO I F2

Electron impact total (elastic + inelastic) cross sections and total ionization cross sections are calculated for N2O, CF4, NO and F2 molecules from the thresholds to 5 keV. A model complex optical potential is calculated for each collision system from the corresponding molecular wave function at the Hartree-Fock level. The resulting complex optical potential, free from any adjustable parameter, is treated exactly in a variable-phase approach to calculate scattering complex phase shifts and the total cross sections. The present results are found to be consistent with the existing experimental measurements.Izračunali smo ukupne elektronske sudarne (elastične i neelastične) i ukupne ionizacijske udarne presjeke za molekule N2O, CF4, NO i F2 za energije od praga do 5 keV. Modelske kompleksne optičke potencijale smo izračunali za svaki sustav na osnovi odgovarajućih molekulskih Hartree-Fockovih valnih funkcija. Postignute optičke potencijale, bez parametara za podešavanje, primijenili smo egzaktno s promjenljivim fazama u računima kompleksnih faznih pomaka i ukupnih udarnih presjeka. Ishodi računa su u skladu s dostupnim rezultatima mjerenja

Making waves : wastewater-based epidemiology for COVID-19 - approaches and challenges for surveillance and prediction

The presence of SARS-CoV-2 in the feces of infected patients and wastewater has drawn attention, not only to the possibility of fecal-oral transmission but also to the use of wastewater as an epidemiological tool. The COVID-19 pandemic has highlighted problems in evaluating the epidemiological scope of the disease using classical surveillance approaches, due to a lack of diagnostic capacity, and their application to only a small proportion of the population. As in previous pandemics, statistics, particularly the proportion of the population infected, are believed to be widely underestimated. Furthermore, analysis of only clinical samples cannot predict outbreaks in a timely manner or easily capture asymptomatic carriers. Threfore, community-scale surveillance, including wastewater-based epidemiology, can bridge the broader community and the clinic, becoming a valuable indirect epidemiological prediction tool for SARS-CoV-2 and other pandemic viruses. This article summarizes current knowledge and discusses the critical factors for implementing wastewater-based epidemiology of COVID-19

Inductive learning spatial attention

This paper investigates the automatic induction of spatial attention from the visual observation of objects manipulated on a table top. In this work, space is represented in terms of a novel observer-object relative reference system, named Local Cardinal System, defined upon the local neighbourhood of objects on the table. We present results of applying the proposed methodology on five distinct scenarios involving the construction of spatial patterns of coloured blocks

Ab initio calculations of Ca III Stark broadening parameters,transition probabilities and radiative lifetimes

We have determined matrix elements for all experimental configurations of Ca III, including the 3s3p63d configuration. These values have been obtained using intermediate coupling (IC). For these IC calculations, we have used the standard method of least-squares fitting from the experimental energy levels, using the computer code developed by Robert Cowan. In this paper, using these matrix elements, we report the calculated values of the Ca III Stark widths and shifts for 148 spectral lines, of 56 Ca III spectral line transition probabilities and of eight radiative lifetimes of Ca III levels. The Stark widths and shifts, calculated using the Griem semi-empirical approach, correspond to the spectral lines of Ca III and are presented for an electron density of 1017 cm?3 and temperatures T = 1.0?10.0 (×104 K). The theoretical trends of the Stark broadening parameter versus the temperature are presented for transitions that are of astrophysical interest. There is good agreement between our calculations, for transition probabilities and radiative lifetimes, and the experimental values presented in the literature. We have not been able to find any values for the Stark parameters in the references

Potential of a multiparametric optical sensor for determining in situ the maturity components of red and white vitis vinifera wine grapes

A non-destructive fluorescence-based technique for evaluating Vitis vinifera L. grape maturity using a portable sensor (Multiplex ®) is presented. It provides indices of anthocyanins and chlorophyll in Cabernet Sauvignon, Merlot and Sangiovese red grapes and of flavonols and chlorophyll in Vermentino white grapes. The good exponential relationship between the anthocyanin index and the actual anthocyanin content determined by wet chemistry was used to estimate grape anthocyanins from in field sensor data during ripening. Marked differences were found in the kinetics and the amount of anthocyanins between cultivars and between seasons. A sensor-driven mapping of the anthocyanin content in the grapes, expressed as g/kg fresh weight, was performed on a 7-ha vineyard planted with Sangiovese. In the Vermentino, the flavonol index was favorably correlated to the actual content of berry skin flavonols determined by means of HPLC analysis of skin extracts. It was used to make a non-destructive estimate of the evolution in the flavonol concentration in grape berry samplings. The chlorophyll index was inversely correlated in linear manner to the total soluble solids (°Brix): it could, therefore, be used as a new index of technological maturity. The fluorescence sensor (Multiplex) possesses a high potential for representing an important innovative tool for controlling grape maturity in precision viticulture