Orbital-selective time-domain signature of nematicity dynamics in the charge-density-wave phase of La1.65Eu0.2Sr0.15CuO4.

Understanding the interplay between charge, nematic, and structural ordering tendencies in cuprate superconductors is critical to unraveling their complex phase diagram. Using pump-probe time-resolved resonant X-ray scattering on the (0 0 1) Bragg peak at the Cu [Formula: see text] and O [Formula: see text] resonances, we investigate nonequilibrium dynamics of [Formula: see text] nematic order and its association with both charge density wave (CDW) order and lattice dynamics in La[Formula: see text]Eu[Formula: see text]Sr[Formula: see text]CuO[Formula: see text]. The orbital selectivity of the resonant X-ray scattering cross-section allows nematicity dynamics associated with the planar O 2[Formula: see text] and Cu 3[Formula: see text] states to be distinguished from the response of anisotropic lattice distortions. A direct time-domain comparison of CDW translational-symmetry breaking and nematic rotational-symmetry breaking reveals that these broken symmetries remain closely linked in the photoexcited state, consistent with the stability of CDW topological defects in the investigated pump fluence regime.

An Actor-Partner interdependence model of parenting difficulties over time in stepfamilies.

Little research has examined the potential spillover of parenting difficulties in the coparental stepfamily subsystem. Using family systems theory as a guide, we longitudinally examined: (a) whether early parenting difficulties within stepfamilies persist 1 year later and (b) whether the parenting difficulties experienced by one partner impact the parenting difficulties of the other partner within remarriages. Copies of marriage licenses were used to identify remarried individuals. Surveys were mailed out, with follow-up surveys mailed a year later, resulting in a sample of 676 remarried couples (the majority of which were White and college educated). The sample was split into three groups, according to stepfamily constellation: (a) families with a stepfather and biological mother; (b) families with a biological father and a stepmother; and (c) families with both stepfathers and stepmothers. We estimated three different actor-partner interdependence models (APIM), one for each group. Consistent with family systems theory, our findings showed that parenting and stepparenting difficulties were interrelated, though gendered in effect. All parenting and stepparenting difficulties displayed actor effects, suggesting that parenting difficulties persist 1 year later. However, the only cross-spouse influences (partner effects) were such that the mother's parenting difficulties (of her own biological children) were predicted by the father's parenting and stepparenting difficulties, and these differed by stepfamily constellation. Implications regarding gendered expectations, the importance of the coparenting subsystem in stepfamilies, early establishment of parental boundaries, and the (potentially important) inclusion of the stepfather in the parenting dynamics are discussed.

High-sensitivity x-ray/optical cross-correlator for next generation free-electron lasers.

We design and realize an arrival time diagnostic for ultrashort X-ray pulses achieving unprecedented high sensitivity in the soft X-ray regime via cross-correlation with a ≈1550 nm optical laser. An interferometric detection scheme is combined with a multi-layer sample design to greatly improve the sensitivity of the measurement. We achieve up to 275% of relative signal change when exposed to 1.6 mJ/cm2 of soft X-rays at 530 eV, more than a hundred-fold improvement in sensitivity as compared to previously reported techniques. The resolution of the arrival time measurement is estimated to around 2.8 fs (rms). The demonstrated X-ray arrival time monitor paves the way for sub-10 fs-level timing jitter at high repetition rate X-ray facilities.

Multivariate analysis of x-ray scattering using a stochastic source.

The normalization of scattered intensity by incident flux is a crucial step in analyzing data from stochastic x-ray free electron laser sources and is complicated by non-linearities traditionally attributed to detector saturation. Here we show that such non-linearities can also arise when the sample spectra are non-uniform within the monochromator bandwidth. A method for modeling and removing this non-linearity using multivariate regression with shot-by-shot x-ray photon energy as an independent variable is presented. This approach demonstrates the benefit of event building and will allow for a reconsideration of data which has proven challenging to normalize.

A novel method for resonant inelastic soft X-ray scattering via photoelectron spectroscopy detection.

A method for measuring resonant inelastic X-ray scattering based on the conversion of X-ray photons into photoelectrons is presented. The setup is compact, relies on commercially available detectors, and offers significant flexibility. This method is demonstrated at the Linac Coherent Light Source with ∼0.5 eV resolution at the cobalt L3-edge, with signal rates comparable with traditional grating spectrometers.

Formal Alternative Transportation Options for Older Adults: An Assessment of Need.

This study measured the need for formal alternative modes of transportation among older adults by applying traditional factors of the Behavioral Model. Survey participants who regularly drove were compared to those who could no longer drive. Race/ethnicity and self-reported health were significant predictors of perceived need for transportation services for both groups. However, income and service awareness were significant predictors only for drivers, while family proximity was a significant predictor only for non-drivers. Results suggest the importance of gaining a better understanding of the factors associated with need for senior-focused transportation services to more effectively plan such programs.

X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser.

X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. Here we compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based on self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. We show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements.

The Soft X-ray Research instrument at the Linac Coherent Light Source.

The Soft X-ray Research instrument provides intense ultrashort X-ray pulses in the energy range 280-2000 eV. A diverse set of experimental stations may be installed to investigate a broad range of scientific topics such as ultrafast chemistry, highly correlated materials, magnetism, surface science, and matter under extreme conditions. A brief description of the main instrument components will be given, followed by some selected scientific highlights.

Pulse energy measurement at the SXR instrument.

A gas monitor detector was implemented and characterized at the Soft X-ray Research (SXR) instrument to measure the average, absolute and pulse-resolved photon flux of the LCLS beam in the energy range between 280 and 2000 eV. The detector is placed after the monochromator and addresses the need to provide reliable absolute pulse energy as well as pulse-resolved measurements for the various experiments at this instrument. This detector provides a reliable non-invasive measurement for determining flux levels on the samples in the downstream experimental chamber and for optimizing signal levels of secondary detectors and for the essential need of data normalization. The design, integration into the instrument and operation are described, and examples of its performance are given.

Combining THz laser excitation with resonant soft X-ray scattering at the Linac Coherent Light Source.

This paper describes the development of new instrumentation at the Linac Coherent Light Source for conducting THz excitation experiments in an ultra high vacuum environment probed by soft X-ray diffraction. This consists of a cantilevered, fully motorized mirror system which can provide 600 kV cm(-1) electric field strengths across the sample and an X-ray detector that can span the full Ewald sphere with in-vacuum motion. The scientific applications motivated by this development, the details of the instrument, and spectra demonstrating the field strengths achieved using this newly developed system are discussed.

Child Contact, Partner Conflict, and Psychological Distress Among Incarcerated Fathers: Testing the Mediating Role of Perceived Social Support.

The mechanism(s) through which child contact can lead to more positive mental health and romantic relationship outcomes among incarcerated fathers are not sufficiently studied. The present study tests whether the associations between frequency of child contact and later psychological distress and conflict in romantic relationships are mediated by perceived social support. Self-reported longitudinal data from a sample of incarcerated men who participated in a fatherhood education program (n = 2,096) were analyzed using structural equation modeling. Variables were assessed pre- and post-program participation. As hypothesized, more frequent child contact was associated with greater perceived social support, which predicted reduced psychological distress and reduced partner conflict. There were significant indirect effects of child contact on psychological distress and partner conflict via perceived social support. The findings may inform policies aiming to help incarcerated fathers to better manage psychological distress and conflictual relationships, preparing them for a more successful return to society.

High-resolution x-ray diffraction microscopy of specifically labeled yeast cells.

X-ray diffraction microscopy complements other x-ray microscopy methods by being free of lens-imposed radiation dose and resolution limits, and it allows for high-resolution imaging of biological specimens too thick to be viewed by electron microscopy. We report here the highest resolution (11-13 nm) x-ray diffraction micrograph of biological specimens, and a demonstration of molecular-specific gold labeling at different depths within cells via through-focus propagation of the reconstructed wavefield. The lectin concanavalin A conjugated to colloidal gold particles was used to label the alpha-mannan sugar in the cell wall of the yeast Saccharomyces cerevisiae. Cells were plunge-frozen in liquid ethane and freeze-dried, after which they were imaged whole using x-ray diffraction microscopy at 750 eV photon energy.

Capturing dynamical correlations using implicit neural representations.

Understanding the nature and origin of collective excitations in materials is of fundamental importance for unraveling the underlying physics of a many-body system. Excitation spectra are usually obtained by measuring the dynamical structure factor, S(Q, ω), using inelastic neutron or x-ray scattering techniques and are analyzed by comparing the experimental results against calculated predictions. We introduce a data-driven analysis tool which leverages 'neural implicit representations' that are specifically tailored for handling spectrographic measurements and are able to efficiently obtain unknown parameters from experimental data via automatic differentiation. In this work, we employ linear spin wave theory simulations to train a machine learning platform, enabling precise exchange parameter extraction from inelastic neutron scattering data on the square-lattice spin-1 antiferromagnet La2NiO4, showcasing a viable pathway towards automatic refinement of advanced models for ordered magnetic systems.

Femtosecond single-shot imaging of nanoscale ferromagnetic order in Co/Pd multilayers using resonant x-ray holography.

We present the first single-shot images of ferromagnetic, nanoscale spin order taken with femtosecond x-ray pulses. X-ray-induced electron and spin dynamics can be outrun with pulses shorter than 80 fs in the investigated fluence regime, and no permanent aftereffects in the samples are observed below a fluence of 25 mJ/cm(2). Employing resonant spatially muliplexed x-ray holography results in a low imaging threshold of 5 mJ/cm(2). Our results open new ways to combine ultrafast laser spectroscopy with sequential snapshot imaging on a single sample, generating a movie of excited state dynamics.

Economic distress and perceptions of sexual intimacy in remarriage.

Introduction: Economic distress and the relationship stability of remarried couples has been subject to some exploration, but less emphasis has been placed on how economic distress among remarried couples impacts other relationship domains, particularly sexual intimacy. Methods: Through the lens of multidimensional family development theory (MFDT), this study utilizes longitudinal data over a three-year period to examine the links between economic distress, couple engagement, relationship satisfaction, and perceptions of sexual intimacy among remarried couples (n = 1,161 couples; 97% White). Results: Through a dyadic structural equation model, results showed that wives' report of economic distress was directly related to their self-rejection of a partner's sexual advances. Findings also revealed gender differences in how both relationship satisfaction and couple engagement influenced one to accept or reject their partner's sexual advances, with couple engagement acting as a significant predictor for wives. Relationship satisfaction was also found to explain (i.e., mediate) the relation between economic distress and sexual intimacy, but only for husbands. Discussion: Implications for further research and interventions designed to strengthen the relationships of remarried couples dealing with economic distress and intimacy issues are offered.

Tunable x-ray free electron laser multi-pulses with nanosecond separation.

X-ray Free Electron Lasers provide femtosecond x-ray pulses with narrow bandwidth and unprecedented peak brightness. Special modes of operation have been developed to deliver double pulses for x-ray pump, x-ray probe experiments. However, the longest delay between the two pulses achieved with existing single bucket methods is less than 1 picosecond, thus preventing the exploration of longer time-scale dynamics. We present a novel two-bucket scheme covering delays from 350 picoseconds to hundreds of nanoseconds in discrete steps of 350 picoseconds. Performance for each pulse can be similar to the one in a single pulse operation. The method has been experimentally tested with the Linac Coherent Light Source (LCLS-I) and the copper linac with LCLS-II hard x-ray undulators.

A machine learning photon detection algorithm for coherent x-ray ultrafast fluctuation analysis.

X-ray free electron laser experiments have brought unique capabilities and opened new directions in research, such as creating new states of matter or directly measuring atomic motion. One such area is the ability to use finely spaced sets of coherent x-ray pulses to be compared after scattering from a dynamic system at different times. This enables the study of fluctuations in many-body quantum systems at the level of the ultrafast pulse durations, but this method has been limited to a select number of examples and required complex and advanced analytical tools. By applying a new methodology to this problem, we have made qualitative advances in three separate areas that will likely also find application to new fields. As compared to the "droplet-type" models, which typically are used to estimate the photon distributions on pixelated detectors to obtain the coherent x-ray speckle patterns, our algorithm achieves an order of magnitude speedup on CPU hardware and two orders of magnitude improvement on GPU hardware. We also find that it retains accuracy in low-contrast conditions, which is the typical regime for many experiments in structural dynamics. Finally, it can predict photon distributions in high average-intensity applications, a regime which up until now has not been accessible. Our artificial intelligence-assisted algorithm will enable a wider adoption of x-ray coherence spectroscopies, by both automating previously challenging analyses and enabling new experiments that were not otherwise feasible without the developments described in this work.

X-ray diffraction microscopy of magnetic structures.

We report the first proof-of-principle experiment of iterative phase retrieval from magnetic x-ray diffraction. By using the resonant x-ray excitation process and coherent x-ray scattering, we show that linearly polarized soft x rays can be used to image both the amplitude and the phase of magnetic domain structures. We recovered the magnetic structure of an amorphous terbium-cobalt thin film with a spatial resolution of about 75 nm at the Co L3 edge at 778 eV. In comparison with soft x-ray microscopy images recorded with Fresnel zone plate optics at better than 25 nm spatial resolution, we find qualitative agreement in the observed magnetic structure.

Following Metal-to-Ligand Charge-Transfer Dynamics with Ligand and Spin Specificity Using Femtosecond Resonant Inelastic X-ray Scattering at the Nitrogen K-Edge.

We demonstrate for the case of photoexcited [Ru(2,2'-bipyridine)3]2+ how femtosecond resonant inelastic X-ray scattering (RIXS) at the ligand K-edge allows one to uniquely probe changes in the valence electronic structure following a metal-to-ligand charge-transfer (MLCT) excitation. Metal-ligand hybridization is probed by nitrogen-1s resonances providing information on both the electron-accepting ligand in the MLCT state and the hole density of the metal center. By comparing to spectrum calculations based on density functional theory, we are able to distinguish the electronic structure of the electron-accepting ligand and the other ligands and determine a temporal upper limit of (250 ± 40) fs for electron localization following the charge-transfer excitation. The spin of the localized electron is deduced from the selection rules of the RIXS process establishing new experimental capabilities for probing transient charge and spin densities.

Incorrect support and missing center tolerances of phasing algorithms.

In x-ray diffraction microscopy, iterative algorithms retrieve reciprocal space phase information, and a real space image, from an object's coherent diffraction intensities through the use of a priori information such as a finite support constraint. In many experiments, the object's shape or support is not well known, and the diffraction pattern is incompletely measured. We describe here computer simulations to look at the effects of both of these possible errors when using several common reconstruction algorithms. Overly tight object supports prevent successful convergence; however, we show that this can often be recognized through pathological behavior of the phase retrieval transfer function. Dynamic range limitations often make it difficult to record the central speckles of the diffraction pattern. We show that this leads to increasing artifacts in the image when the number of missing central speckles exceeds about 10, and that the removal of unconstrained modes from the reconstructed image is helpful only when the number of missing central speckles is less than about 50. This simulation study helps in judging the reconstructability of experimentally recorded coherent diffraction patterns.