Maximum population transfer in a periodically driven two-level system

We study the dynamics of a two-level quantum system under the influence of sinusoidal driving in the intermediate frequency regime. Analyzing the Floquet quasienergy spectrum, we find combinations of the field parameters for which population transfer is optimal and takes place through a series of well defined steps of fixed duration. We also show how the corresponding evolution operator can be approximated at all times by a very simple analytical expression. We propose this model as being specially suitable for treating periodic driving at avoided crossings found in complex multi-level systems, and thus show a relevant application of our results to designing a control protocol in a realistic molecular modelComment: 7 pages, 6 figure

The Poincare-Birkhoff theorem in Quantum Mechanics

Quantum manifestations of the dynamics around resonant tori in perturbed Hamiltonian systems, dictated by the Poincar\'e--Birkhoff theorem, are shown to exist. They are embedded in the interactions involving states which differ in a number of quanta equal to the order of the classical resonance. Moreover, the associated classical phase space structures are mimicked in the quasiprobability density functions and their zeros.Comment: 5 pages, 3 figures, Full resolution figures available at http://www.df.uba.ar/users/wisniaki/publications.htm

Correspondence between classical and quantum resonances

Bifurcations take place in molecular Hamiltonian nonlinear systems as the excitation energy increases, leading to the appearance of different classical resonances. In this paper, we study the quantum manifestations of these classical resonances in the isomerizing system CN-Li Li-CN. By using a correlation diagram of eigenenergies versus Planck constant, we show the existence of different series of avoided crossings, leading to the corresponding series of quantum resonances, which represent the quantum manifestations of the classical resonances. Moreover, the extrapolation of these series to h = 0 unveils the correspondence between the bifurcation energy of classical resonances and the energy of the series of quantum resonances in the semiclassical limit → 0. Additionally, in order to obtain analytical expressions for our results, a semiclassical theory is develope

Earth Occultation Imaging of the Low Energy Gamma-Ray Sky with GBM

The Earth Occultation Technique (EOT) has been applied to Fermi's Gamma-ray Burst Monitor (GBM) to perform all-sky monitoring for a predetermined catalog of hard X-ray/soft gamma-ray sources. In order to search for sources not in the catalog, thus completing the catalog and reducing a source of systematic error in EOT, an imaging method has been developed -- Imaging with a Differential filter using the Earth Occultation Method (IDEOM). IDEOM is a tomographic imaging method that takes advantage of the orbital precession of the Fermi satellite. Using IDEOM, all-sky reconstructions have been generated for ~sim 4 years of GBM data in the 12-50 keV, 50-100 keV and 100-300 keV energy bands in search of sources otherwise unmodeled by the GBM occultation analysis. IDEOM analysis resulted in the detection of 57 sources in the 12-50 keV energy band, 23 sources in the 50-100 keV energy band, and 7 sources in the 100-300 keV energy band. Seventeen sources were not present in the original GBM-EOT catalog and have now been added. We also present the first joined averaged spectra for four persistent sources detected by GBM using EOT and by the Large Area Telescope (LAT) on Fermi: NGC 1275, 3C 273, Cen A, and the Crab

The development of a resource-efficient photovoltaic system

This paper presents the measures taken in the demonstration of the photovoltaic case study developed within the European project ‘Towards zero waste in industrial networks’ (Zerowin), integrating the D4R (Design for recycling, repair, refurbishment and reuse) criteria at both system and industrial network level. The demonstration is divided into three phases. The first phase concerns the development of a D4R photovoltaic concept, the second phase focused on the development of a specific component of photovoltaic systems and the third phase was the demonstration of the D4R design in two complete photovoltaic systems (grid-connected and stand-alone). This paper includes a description of the installed photovoltaic systems, including a brief summary at component level of the lithium ion battery system and the D4R power conditioning system developed for the pilot installations. Additionally, industrial symbioses within the network associated with the photovoltaic systems and the production model for the network are described

A 0535+26: an X-ray/Optical Tour

We compiled X-ray and Optical observations of the accreting X-ray binary system A 0535+262 since its discovery in 1975, that will allow us to shed light on the unpredictable behavior of this binary system. We present the data in terms of the Be-disk interaction with the neutron star companion. In addition, we show recent results from the continuous monitoring of this source by the Gamma-ray Burst Monitor(GBM), on board the Fermi observatory, since its launch in 2008 June 11.Comment: 4 pages, 5 figures, Conference proceeding of "Astrophysics of Neutron Stars 2010 - a conference in honor of M. Ali Alpar", 2-6 August 2010, Cesme, Izmir, Turke

Crowdsourcing malaria parasite quantification: an online game for analyzing images of infected thick blood smears

Background: There are 600,000 new malaria cases daily worldwide. The gold standard for estimating the parasite burden and the corresponding severity of the disease consists in manually counting the number of parasites in blood smears through a microscope, a process that can take more than 20 minutes of an expert microscopist’s time. Objective: This research tests the feasibility of a crowdsourced approach to malaria image analysis. In particular, we investigated whether anonymous volunteers with no prior experience would be able to count malaria parasites in digitized images of thick blood smears by playing a Web-based game. Methods: The experimental system consisted of a Web-based game where online volunteers were tasked with detecting parasites in digitized blood sample images coupled with a decision algorithm that combined the analyses from several players to produce an improved collective detection outcome. Data were collected through the MalariaSpot website. Random images of thick blood films containing Plasmodium falciparum at medium to low parasitemias, acquired by conventional optical microscopy, were presented to players. In the game, players had to find and tag as many parasites as possible in 1 minute. In the event that players found all the parasites present in the image, they were presented with a new image. In order to combine the choices of different players into a single crowd decision, we implemented an image processing pipeline and a quorum algorithm that judged a parasite tagged when a group of players agreed on its position. Results: Over 1 month, anonymous players from 95 countries played more than 12,000 games and generated a database of more than 270,000 clicks on the test images. Results revealed that combining 22 games from nonexpert players achieved a parasite counting accuracy higher than 99%. This performance could be obtained also by combining 13 games from players trained for 1 minute. Exhaustive computations measured the parasite counting accuracy for all players as a function of the number of games considered and the experience of the players. In addition, we propose a mathematical equation that accurately models the collective parasite counting performance. Conclusions: This research validates the online gaming approach for crowdsourced counting of malaria parasites in images of thick blood films. The findings support the conclusion that nonexperts are able to rapidly learn how to identify the typical features of malaria parasites in digitized thick blood samples and that combining the analyses of several users provides similar parasite counting accuracy rates as those of expert microscopists. This experiment illustrates the potential of the crowdsourced gaming approach for performing routine malaria parasite quantification, and more generally for solving biomedical image analysis problems, with future potential for telediagnosis related to global health challenges

Unraveling the highly nonlinear dynamics of KCN molecular system using Lagrangian descriptors

In this work, we identify the phase-space structures which are responsible for the chaotic dynamics observed in KCN molecular system using the Lagrangian descriptors. We show that the vibrational dynamics of this molecule is strongly determined by the invariant manifolds associated with a particular stretching periodic orbit previously described (Párraga et al., 2018). Likewise, the representation of these invariant manifolds on a Poincaré surface of section is also studied, concluding that the intricate depiction that is observed has its origin in the complex behavior of the manifolds, which is a consequence of the strong anharmonicities in the potential energy surfaceThis work has been partially supported by the Grants PID2021-122711NB-C21 and CEX2019-000904-S funded by MCIN/AEI/10.13039/501100011033, by the People Programme (Marie Curie Actions) of the European Union’s Horizon 2020 Research and Innovation Program under Grant No. 734557, and by the Comunidad de Madrid, Spain under the Grant APOYO-JOVENES-4L2UB6-53-29443N (GeoCoSiM) financed within the Plurianual Agreement with the Universidad Politécnica de Madrid, Spain in the line to improve the research of young doctor

Caracterización y cartografía fitoclimáticas del bosque nativo subantártico en la Isla Grande de Tierra del Fuego (Patagonia, Argentina)

Isla Grande de Tierra del Fuego is especially peculiar in phytoclimatic terms, situated as it is at an extreme southerly latitude, surrounded by large water masses and close to the great mass of Antarctic ice. Its main peculiarities in this sense are the coolness of its summers and a very narrow temperature range. As a result, the woodland landscapes in the parts with forest cover are dominated by microphyllous broadleaf physiognomies, both evergreen and deciduous, of the Nothofagus genus. This paper reports a more in-depth investigation of the hitherto little-known phytoclimatic conditions in that territory which included calibration and validation of a model of phytoclimatic suitability that addresses the principal plant physiognomic units and phytoclimatic mapping. It discusses the causes behind the presence of broadleaf formations in thermal conditions which in the northern hemisphere would allow only coniferous formations or no tree formations at all, and also the edaphic peculiarities that may explain the presence of a evergreen species like Nothofagus betuloides in subantarctic mixed forests.La Isla Grande de Tierra del Fuego presenta una muy marcada originalidad fitoclimática por su posición en latitudes muy australes, estar rodeada por grandes masas de agua y por su cercanía a la gran masa de hielo polar antártica. Esta originalidad se traduce en un escaso calor estival y una oscilación térmica muy reducida como principales peculiaridades, dando lugar en sus porciones arboladas a paisajes boscosos dominados por fisionomías planifolias de carácter micrófilo, tanto perennifolias como caducifolias del género Nothofagus. Este trabajo profundiza en las hasta hoy escasamente conocidas condiciones fitoclimáticas de este territorio, mediante la calibración y validación de un modelo de idoneidad fitoclimática respecto de las principales unidades fisionómicas de vegetación y el establecimiento de una cartografía fitoclimática. Se discuten las causas que provocan la existencia de formaciones planifolias en condiciones térmicas que darían lugar a formaciones aciculifolias o desarboladas en el hemisferio Norte, así como las particularidades edáficas que condicionan la presencia de la estrategia perennifolia representada por Nothofagus betuloides en los bosques mixtos subantárticos