We investigate the linear and nonlinear evolution of the current-driven ion-acoustic instability in a collisionless plasma via two-dimensional (2-D) Vlasov–Poisson numerical simulations. We initialise the system in a stable state and gradually drive it towards instability with an imposed, weak external electric field, thus avoiding physically unrealisable super-critical initial conditions. A comprehensive analysis of the nonlinear evolution of ion-acoustic turbulence (IAT) is presented, including the detailed characteristics of the evolution of the particles’ distribution functions, (2-D) wave spectrum and the resulting anomalous resistivity. Our findings reveal the dominance of 2-D quasi-linear effects around saturation, with nonlinear effects, such as particle trapping and nonlinear frequency shifts, becoming pronounced during the later stages of the system's nonlinear evolution. Remarkably, the Kadomtsev–Petviashvili (KP) spectrum is observed immediately after the saturation of the instability. Another crucial and noteworthy result is that no steady saturated nonlinear state is ever reached: strong ion heating suppresses the instability, which implies that the anomalous resistivity associated with IAT is transient and short-lived, challenging earlier theoretical results. Towards the conclusion of the simulation, electron-acoustic waves are triggered by the formation of a double layer and strong modifications to the particle distribution induced by IAT.

Unauthorized cultural resource alterations range from looting and grave robbing to contract violations and wildland fires. Such alterations degrade cultural resources’ spiritual, communal, ecological, economic, and scientific values. Alterations often violate communal senses of place, security, and belonging. Alterations complicate jurisdiction-specific management, which is premised on up-to-date information on resource sizes, conditions, and significance. Cultural resource damage assessment protocols based on proven forensic practices distil to eight fieldwork steps: verify the alteration, assemble the team, survey the scene, document the evidence, gather the evidence, assess the archaeological value and the cost of repair and restoration, prescribe emergency remediation, and confirm evidence documentation and custody. The eight steps give special consideration to local communities and Indigenous Territories, where unauthorized alterations are as common as they are elsewhere, whereas impacts to spiritual and cultural values are generally greater. Adapted to jurisdiction- and incident-specific circumstances, the steps will guide responses to alterations by community leaders, land managers, regulators, law enforcement agents, and archaeologists, including preparation of excellent damage assessment reports. Damage assessment practitioners and land managers should refine these practices to deter alterations, engage Tribes and other affected communities, halt postalteration degradation, ensure accountability, and enable jurisdiction-scale curation of cultural resources and their unique value constellations.

Psychopathology and cognitive development are closely related. Assessing the relationship between multiple domains of psychopathology and cognitive performance can elucidate which cognitive tasks are related to specific domains of psychopathology. This can help build theory and improve clinical decision-making in the future. In this study, we included 13,841 children and adolescents drawn from two large population-based samples (Generation R and ABCD studies). We assessed the cross-sectional relationship between three psychopathology domains (internalizing, externalizing, dysregulation profile (DP)) and four cognitive domains (vocabulary, fluid reasoning, working memory, and processing speed) and the full-scale intelligence quotient. Lastly, differential associations between symptoms of psychopathology and cognitive performance by sex were assessed. Results indicated that internalizing symptoms were related to worse performance in working memory and processing speed, but better performance in the verbal domain. Externalizing and DP symptoms were related to poorer global cognitive performance. Notably, those in the DP subgroup had a 5.0 point lower IQ than those without behavioral problems. Cognitive performance was more heavily affected in boys than in girls given comparable levels of psychopathology. Taken together, we provide evidence for globally worse cognitive performance in children and adolescents with externalizing and DP symptoms, with those in the DP subgroup being most heavily affected.

We describe an ultra-wide-bandwidth, low-frequency receiver recently installed on the Parkes radio telescope. The receiver system provides continuous frequency coverage from 704 to 4032 MHz. For much of the band ( ${\sim}60\%$ ), the system temperature is approximately 22 K and the receiver system remains in a linear regime even in the presence of strong mobile phone transmissions. We discuss the scientific and technical aspects of the new receiver, including its astronomical objectives, as well as the feed, receiver, digitiser, and signal processor design. We describe the pipeline routines that form the archive-ready data products and how those data files can be accessed from the archives. The system performance is quantified, including the system noise and linearity, beam shape, antenna efficiency, polarisation calibration, and timing stability.

A 2018 workshop on the White Mountain Apache Tribe lands in Arizona examined ways to enhance investigations into cultural property crime (CPC) through applications of rapidly evolving methods from archaeological science. CPC (also looting, graverobbing) refers to unauthorized damage, removal, or trafficking in materials possessing blends of communal, aesthetic, and scientific values. The Fort Apache workshop integrated four generally partitioned domains of CPC expertise: (1) theories of perpetrators’ motivations and methods; (2) recommended practice in sustaining public and community opposition to CPC; (3) tactics and strategies for documenting, investigating, and prosecuting CPC; and (4) forensic sedimentology—uses of biophysical sciences to link sediments from implicated persons and objects to crime scenes. Forensic sedimentology served as the touchstone for dialogues among experts in criminology, archaeological sciences, law enforcement, and heritage stewardship. Field visits to CPC crime scenes and workshop deliberations identified pathways toward integrating CPC theory and practice with forensic sedimentology’s potent battery of analytic methods.

Although restricting formal voting rights—voter suppression—is not uncommon in democracies, its incidence and form vary widely. Intuitively, when competing elites believe that the benefits of reducing voting by opponents outweigh the costs of voter suppression, it is more likely to occur. Internal political and state capacity and external actors, however, influence the form that voter suppression takes. When elites competing for office lack the ability to enact laws restricting voting due to limited internal capacity, or external actors are able to limit the ability of governments to use laws to suppress voting, suppression is likely to be ad hoc, decentralized, and potentially violent. As political and state capacity increase and external constraints decrease, voter suppression will shift from decentralized and potentially violent to centralized and mostly non-violent. We illustrate our arguments by analyzing the transition from decentralized, violent voter suppression through the use of lynchings (and associated violence) to the centralized, less violent suppression of black voting in the post-Reconstruction South. We also place the most recent wave of U.S. state voter suppression laws into broader context using our theoretical framework.

This study examined whether the association between age and amygdala–medial prefrontal cortex (mPFC) connectivity in typically developing 6- to 10-year-old children is correlated with parental care. Resting-state functional magnetic resonance imaging scans were acquired from 124 children of the Generation R Study who at 4 years old had been observed interacting with their parents to assess maternal and paternal sensitivity. Amygdala functional connectivity was assessed using a general linear model with the amygdalae time series as explanatory variables. Higher level analyses assessing Sensitivity × Age as well as exploratory Sensitivity × Age × Gender interaction effects were performed restricted to voxels in the mPFC. We found significant Sensitivity × Age interaction effects on amygdala–mPFC connectivity. Age was related to stronger amygdala–mPFC connectivity in children with a lower combined parental sensitivity score (b = 0.11, p = .004, b = 0.06, p = .06, right and left amygdala, respectively), but not in children with a higher parental sensitivity score, (b = –0.07, p = .12, b = –0.06, p = .12, right and left amygdala, respectively). A similar effect was found for maternal sensitivity, with stronger amygdala–mPFC connectivity in children with less sensitive mothers. Exploratory (parental, maternal, paternal) Sensitivity × Age × Gender interaction analyses suggested that this effect was especially pronounced in girls. Amygdala-mPFC resting-state functional connectivity has been shown to increase from age 10.5 years onward, implying that the positive association between age and amygdala–mPFC connectivity in 6- to 10-year-old children of less sensitive parents represents accelerated development of the amygdala–mPFC circuit.

A microchannel plate was used as an ion sensitive detector in a commercial helium ion microscope (HIM) for dark-field transmission imaging of nanomaterials, i.e. scanning transmission ion microscopy (STIM). In contrast to previous transmission HIM approaches that used secondary electron conversion holders, our new approach detects forward-scattered helium ions on a dedicated annular shaped ion sensitive detector. Minimum collection angles between 125 mrad and 325 mrad were obtained by varying the distance of the sample from the microchannel plate detector during imaging. Monte Carlo simulations were used to predict detector angular ranges at which dark-field images with atomic number contrast could be obtained. We demonstrate atomic number contrast imaging via scanning transmission ion imaging of silica-coated gold nanoparticles and magnetite nanoparticles. Although the resolution of STIM is known to be degraded by beam broadening in the substrate, we imaged magnetite nanoparticles with high contrast on a relatively thick silicon nitride substrate. We expect this new approach to annular dark-field STIM will open avenues for more quantitative ion imaging techniques and advance fundamental understanding of underlying ion scattering mechanisms leading to image formation.

We present an overview of the survey for radio emission from active stars that has been in progress for the last six years using the observatories at Fleurs, Molonglo, Parkes and Tidbinbilla. The role of complementary optical observations at the Anglo-Australian Observatory, Mount Burnett, Mount Stromlo and Siding Spring Observatories and Mount Tamborine are also outlined. We describe the different types of star that have been included in our survey and discuss some of the problems in making the radio observations.

Previous studies have suggested that prenatal maternal folate deficiency is associated with reduced prenatal brain growth and psychological problems in offspring. However, little is known about the longer-term impact. The aims of this study were to investigate whether prenatal maternal folate insufficiency, high total homocysteine levels and low vitamin B12 levels are associated with altered brain morphology, cognitive and/or psychological problems in school-aged children. This study was embedded in Generation R, a prospective population-based cohort study. The study sample consisted of 256 Dutch children aged between 6 and 8 years from whom structural brain scans were collected using MRI. The mothers of sixty-two children had insufficient (<8 nmol/l) plasma folate concentrations in early pregnancy. Cognitive development was assessed by the Snijders-Oomen Niet-verbale intelligentietest – Revisie and the NEPSY-II-NL. Psychological problems were assessed at age 6 years using the parent report of the Child Behavior Checklist. Low prenatal folate levels were associated with a smaller total brain volume (B –33·34; 95 % CI –66·7, 0·02; P=050) and predicted poorer performance on the language (B –0·28; 95 % CI –0·52, –0·04; P=0·020) and visuo-spatial domains (B –0·27; 95 % CI –0·50, –0·04; P=0·021). High homocysteine levels (>9·1 µmol/l) predicted poorer performance on the language (B –0·31; 95 % CI –0·56, –0·06; P=0·014) and visuo-spatial domains (B –0·36; 95 % CI –0·60, –0·11; P=0·004). No associations with psychological problems were found. Our findings suggest that folate insufficiency in early pregnancy has a long-lasting, global effect on brain development and is, together with homocysteine levels, associated with poorer cognitive performance.

Improved powder XRD patterns for the titanium suboxides, TinO2n−1 (4≤n≤9), have been calculated from published single-crystal structures. To provide the best match with experimental data, the entire diffraction traces were simulated, and d-spacings and intensities extracted in the same manner as from experimental traces. The accuracy of the new patterns has been verified by comparison with measured powder patterns, particularly in the case of the n=4 and n=5 compounds where single-phase powders can be prepared relatively easily. Difficulties experienced preparing higher homologues have been related to the thermodynamic properties of this system.

The paper reports on the fourth (2010) season of fieldwork of the Cyrenaican Prehistory Project, and on further results of analyses of artefacts and organic materials collected in the 2009 season. Ground-based LiDar has provided both an accurate 3D scan of the Haua Fteah cave and information on the cave's morphometry or origins. The excavations in the cave focussed on Middle Palaeolithic or Middle Stone Age ‘Pre-Aurignacian’ layers below the base of the Middle Trench beside the McBurney Deep Sounding (Trench D) and on Final Palaeolithic ‘Oranian’ layers beside the upper part of the Middle Trench (Trench M). Although McBurney referred to the upper part of the Deep Sounding as more or less sterile, the 2010 excavations found evidence for small-scale but regular human presence in the form of stone artefacts and debitage, though given the sedimentary context the latter are unlikely to represent in situ knapping. The excavations of Trench M extended from the basal Capsian layers investigated in 2009 through Oranian layers to the transition with the Dabban Upper Palaeolithic. Some 17,000 lithic pieces have been studied from the Capsian and Oranian layers excavated in Trench M, in an area measuring less than 2 m by 1 m by 1.1 m deep, along with numerous animal bones, molluscs, and macrobotanical remains, as well as occasional shell beads. Preliminary studies of the lithics, bones, molluscs, and plant remains are revealing the changing character of late Pleistocene (Oranian) and early Holocene (Capsian) occupation in the Haua Fteah. Alongside the work in the Haua Fteah, the project continued its assessment of the Quaternary and archaeological sequences of the Cyrenaican coastland and completed a transect survey of surface lithic materials and their landform contexts from the pre-desert across the Gebel Akhdar to the coast, with a new focus on the al-Marj basin. Significant differences are emerging in patterns of Middle Palaeolithic and later hominin occupation and palaeodemography.

The paper reports on the third (2009) season of fieldwork of the Cyrenaican Prehistory Project, and on further results from the analysis of materials collected in the previous (2007 and 2008) fieldwork. Sediments in a 14 m-deep core drilled beside the McBurney trench provide an invaluable overview of the overall stratigraphic sequence, including at depths reached by the 1950s Deep Sounding but not yet investigated by the present project. Sampling of newly-exposed faces of the original excavation trench for dating (14C, ESR, OSL, U-series) and palaeoenvirommental indicators continued. Excavation was begun of sediments assigned to the early Holocene Libyco-Capsian (McBurney's Layer X), and of Pre-Aurignacian layers beside the top of the Deep Sounding. The Libyco-Capsian layers are particularly prolific in lithic debris, shells, and animal bones; preliminary analysis of the lithics suggests a development from Typical to Upper Capsian within the layers excavated in 2009. Geoarchaeological survey along the littoral to the west and east of the Haua Fteah identified complex sequences spanning most of the last interglacial-glacial cycle. Geoarchaeological survey south of the Haua Fteah characterized the major landforms of the Gebel Akhdar mountain and of the pre-desert and desert-edge zones further south, with Late Stone Age (Upper Palaeolithic and Epipalaeolithic) material being found especially on the southern side of the Gebel Akhdar, and Middle Stone Age (Middle Palaeolithic) material in the pre-desert and desert regions. The first suite of 14C dates (from charcoal samples taken in 2007) indicates the use of the Haua Fteah by Oranian hunter-gatherers during the Last Glacial Maximum and in the succeeding millennia, but not in the Younger Dryas cold/dry phase (c. 11,000–10,000 cal. BC), with Libyco-Capsian occupation resuming soon after the beginning of the Holocene c. 9000 cal. BC, suggesting that the cave, and perhaps the Gebel Akhdar in general, have a complex history as refugia for human settlement during the Pleistocene.

ZnO is known to produce a wide variety of nanostructures that have enormous scope for optoelectronic applications. Using an aqueous electrochemical deposition technique, we are able to tightly control a wide range of deposition parameters (Zn2+ concentration, temperature, potential, time) and hence the resulting deposit morphology. By simultaneously conducting synchrotron x-ray absorption spectroscopy (XAS) experiments during the deposition, we are able to directly monitor the growth rates of the nanostructures, as well as providing direct chemical speciation of the films. In situ experiments such as these are critical to understanding the nucleation and growth of such nanostructures.

Recent results from in situ XAS synchrotron experiments demonstrate the growth rates as a function of potential and Zn2+ concentration. These are compared with the electrochemical current density recorded during the deposition, and the final morphology revealed through ex situ high resolution electron microscopy. The results are indicative of two distinct growth regimes, and simultaneous changes in the morphology are observed.

These experiments are complemented by modelling the growth of the rods in the transport-limited case, using the Nernst-Planck equations in 2 dimensions, to yield the growth rate of the volume, length, and radius as a function of time.