Imaging instantaneous electron flow with ultrafast resonant x-ray scattering

We propose a novel way to image dynamical properties of nonstationary electron systems using ultrafast resonant x-ray scattering. Employing a rigorous theoretical analysis within the framework of quantum electrodynamics, we demonstrate that a single scattering pattern from a nonstationary electron system encodes the instantaneous interatomic electron current in addition to the structural information usually obtained by resonant x-ray scattering from stationary systems. Thus, inelastic contributions that are indistinguishable from elastic processes induced by a broadband probe pulse, instead of being a concern, serve as an advantage for time-resolved resonant x-ray scattering. Thereby, we propose an approach combining elastic and inelastic resonant x-ray scattering for imaging dynamics of nonstationary electron systems in both real space and real time. In order to illustrate its power, we show how it can be applied to image the electron hole current in an ionized diatomic molecule

Advanced methods in reproductive medicine: Application of optical nanoscopy, artificial intelligence-assisted quantitative phase microscopy and mitochondrial DNA copy numbers to assess human sperm cells

Declined fertility rate and population is a matter of serious concern, especially in the developed nations. Assisted Reproductive Technologies (ART), including in vitro fertilization (IVF), have provided great hope for infertility treatment and maintaining population growth and social structure. With the help of ART, more than 8 million babies have already been born so far. Despite the worldwide expansion of ART, there is a number of open questions on the IVF success rates. Male factors for infertility contribute equally as female factors, however, male infertility is primarily focused on the “semen quality”. Therefore, the search of new semen parameters for male fertility evaluation and the exploration of the optimal method of sperm selection in IVF have been included among the top 10 research priorities for male infertility and medically assisted reproduction. The development of imaging systems coupled with image processing by Artificial Intelligence (AI) could be the revolutionary step for semen quality analysis and sperm cell selection in IVF procedures. For this work, we applied optical nanoscopy technology for the analysis of human spermatozoa, i.e., label-based Structured Illumination Microscopy (SIM) and non-invasive Quantitative Phase Microscopy (QPM). The SIM results demonstrated a prominent contrast and resolution enhancement for subcellular structures of living sperm cells, especially for mitochondria-containing midpiece, where features around 100 nm length-scale were resolved. Further, non-labeled QPM combined with machine learning technique revealed the association between gradual progressive motility loss and the morphology changes of the sperm head after external exposure to various concentrations of hydrogen peroxide. Moreover, to recognize healthy and stress-affected sperm cells, we applied Deep Neural Networks (DNNs) to QPM images achieving an accuracy of 85.6% on a dataset of 10,163 interferometric images of sperm cells. Additionally, we summarized the evidence from published literature regarding the association between mitochondrial DNA copy numbers (mtDNAcn) and semen quality. To conclude, we set up the high-resolution imaging of living human sperm cells with a remarkable level of subcellular structural details provided by SIM. Next, the morphological changes of sperm heads resulting from peroxidation have been revealed by QPM, which may not be explored by microscopy currently used in IVF settings. Besides, the implementation of DNNs for QPM image processing appears to be a promising tool in the automated classification and selection of sperm cells during IVF procedures. Moreover, the results of our meta-analysis showed an association of mtDNAcn in human sperm cells and semen quality, which seems to be a relevant sperm parameter for routine clinical practice in male fertility assessment

Imaging Electron Dynamics with Ultrashort Light Pulses: A Theory Perspective

A wide range of ultrafast phenomena in various atomic, molecular and condense matter systems is governed by electron dynamics. Therefore, the ability to image electronic motion in real space and real time would provide a deeper understanding of such processes and guide developments of tools to control them. Ultrashort light pulses, which can provide unprecedented time resolution approaching subfemtosecond time scale, are perspective to achieve real-time imaging of electron dynamics. This task is challenging not only from an experimental view, but also from a theory perspective, since standard theories describing light-matter interaction in a stationary regime can provide erroneous results in an ultrafast case as demonstrated by several theoretical studies. We review the theoretical framework based on quantum electrodynamics, which has been shown to be necessary for an accurate description of time-resolved imaging of electron dynamics with ultrashort light pulses. We compare the results of theoretical studies of time-resolved nonresonant and resonant X-ray scattering, and time- and angle-resolved photoelectron spectroscopy and show that the corresponding time-resolved signals encode analogous information about electron dynamics. Thereby, the information about an electronic system provided by these time-resolved techniques is different from the information provided by their time-independent analogues

Theory of x-ray scattering from laser-driven electronic systems

We describe, within the framework of quantum electrodynamics, an interaction between a non-resonant hard x-ray pulse and an electronic system in the presence of a temporally periodic laser field driving electron dynamics in this system. We apply Floquet theory to describe the laser-driven electronic system, and then obtain the scattering probability of an arbitrary nonresonant x-ray pulse from such a system employing the density-matrix formalism. We show that the scattering probability can be connected to the time-dependent electron density of the driven electronic system only under certain conditions, in particular, if the bandwidth of the probe x-ray pulse is sufficiently narrow to spectroscopically resolve transitions to different final states. A special focus is laid on application of the theory to laser-driven crystals in a strongly nonperturbative regime. We show how the time-dependent electron density of a crystal can be reconstructed from energy-resolved scattering patterns. This is illustrated by a calculation of a diffraction signal from a driven MgO crystal.Comment: accepted to Phys Rev

Dimensions of Rhythm: the multi-layered nature of rhythmic style

The paper motivates a new, musical, view on rhythmic variation that focuses on accent and pause distributions on the intonational phrase level and views accenthood broadly as an interplay between relative duration, relative intensity and pitch accentuation. The musical approach to rhythmic variation integrates the study of rhythm into the study of the rest of the prosodic landscape and aims to emphasize the importance of syntagmatic rhythmic variables: rhythmic patterns. The musical approach highlights dramatic contrasts in the use of rhythmic and prosodic resources on the part of Melody, a jock, and Judy, a burnout (Eckert 1989, 2000), two stylistic opposites and the stars of our investigation. Melody’s IPs are characterized by a single accented syllable which often corresponds to the focal accent, while Judy’s IPs contain multiple accented syllables and IP-internal pauses which together comprise a rhythmic pattern. In addition, ‘disfluencies’ in Judy’s speech perform a rhythmic function. Judy’s use of rhythmic patterns and the diversity in the phonetic realization of her accents suggest that she is more expressive in her use of prosodic resources, while Melody’s rhythmic strategies reflect information structure

Second earners and in-work poverty in Europe

Dual or multiple earnership has been considered an important factor to prevent in-work poverty. The aim of this paper is to quantify the impact of second earnership on the risk of in-work poverty and the role of the tax-benefit system in moderating this risk. Our analysis refers to 2014 and employs EUROMOD, the tax-benefit microsimulation model for the European Union and the United Kingdom. In order to assess the role of second earners in preventing in-work poverty we simulate a counterfactual scenario where second earners become unemployed. Our results show that the effect of net replacement rates (i.e. the ratio of household income before and after the transition of second earners to unemployment) on the probability of in-work poverty is negative and statistically significant, but in relative terms it appears to be small compared to the effects of individual labour market characteristics, such as low pay and part-time employment

Attosecond imaging of photo-induced dynamics in molecules using time-resolved photoelectron momentum microscopy

We explore the novel capabilities offered by attosecond extreme ultraviolet and x-ray pulses that can be now generated by free-electron lasers and high-harmonics generation sources for probing photon-induced electron dynamics in molecules. We theoretically analyze how spatial and temporal dependence of charge migration in a pentacene molecule can be followed by means of time-resolved photoelectron microscopy on the attosecond time scale. Performing the analysis, we accurately take into account that an attosecond probe pulse leads to considerable spectral broadening. We demonstrate that the excited-state dynamics of a neutral pentacene molecule in the real space map onto unique features of photoelectron momentum maps.Comment: Accepted to Phys. Rev.

Impact of equity in social protection spending on income poverty and inequality

This study aims to investigate whether higher equity in government social protection spending strongly predicts positive changes in income poverty and inequality. Our approach was to regress the measures of absolute poverty and inequality on the indicators of equity in social protection spending at the country level, controlling for the level of spending and the country wealth measured by per capita GDP. For that purpose, we have compiled a dataset of 535 observations from 101 countries over years 1998–2017, including 199 observations for 70 low- and middle-income countries from Europe, Asia, North and South America, and Africa. Our findings support the proposition that equity in social spending (measured by the share of social protection spending going to the bottom quintile) is a significant and strong predictor of improved distributional outcomes (poverty measured at Int$1.90 a day and inequality measured by the Gini index). Moreover, in low- and middle-income countries in our sample the poverty and inequality reducing impact of this equity measure is stronger than in the sample including all countries. The presence of a significant gap in equity of social protection spending between the high-income countries and the rest of countries included in the study signifies that there is a large potential in improving equity in social protection spending in low- and middle-income countries. Social protection reforms in these countries should be focused on extending the coverage of social protection programs and improving access to social protection for the poorest segments of the population

Impact assessment of alternative reforms of child allowances using RUSMOD - the static tax-benefit microsimulation model for Russia

RUSMOD is a static tax-benefit microsimulation model for Russia. The model can be used for ex post and ex ante evaluation of reforms of personal income taxation and social benefits in Russia. In addition, being compatible with EUROMOD, the Russian model is suitable for simulation of cross-country policy transfers. The aim of this paper is to shed light on various aspects of the model. It discusses specific problems arising in the evaluation of unreported income and benefits non-take up in Russia. The final estimates of poverty and inequality from RUSMOD are very close to those based on National accounts; hence, the model can be seen as a reliable tool for evaluating the current performance of the Russian tax-benefit system and the distributive impact of potential tax-benefit reforms. Then the paper provides an example of application of the model – an analysis of alternative scenarios for improving the design of child allowances in Russia. Currently, this benefit has a poor targeting performance and varies across regions of Russia in terms of design and generosity, which raises serious equity concerns. Redirecting these resources to the poor – by means of better targeting and raising the benefit amounts – brings about significant improvements in overall and child poverty indicators even at the current level of spending. The most sizable impact on poverty is achieved by implementing the unified national design of the program