Let A be an $n \times n$ symmetric matrix with $(A_{i,j})_{i\leqslant j}$ independent and identically distributed according to a subgaussian distribution. We show that

$$ \begin{align*}\mathbb{P}(\sigma_{\min}(A) \leqslant \varepsilon n^{-1/2} ) \leqslant C \varepsilon + e^{-cn},\end{align*} $$

where $\sigma _{\min }(A)$ denotes the least singular value of A and the constants $C,c>0 $ depend only on the distribution of the entries of A. This result confirms the folklore conjecture on the lower tail of the least singular value of such matrices and is best possible up to the dependence of the constants on the distribution of $A_{i,j}$. Along the way, we prove that the probability that A has a repeated eigenvalue is $e^{-\Omega (n)}$, thus confirming a conjecture of Nguyen, Tao and Vu [Probab. Theory Relat. Fields 167 (2017), 777–816].

Many factors affect patient outcome after congenital heart surgery, including the complexity of the heart disease, pre-operative status, patient specific factors (prematurity, nutritional status and/or presence of comorbid conditions or genetic syndromes), and post-operative residual lesions. The Residual Lesion Score is a novel tool for assessing whether specific residual cardiac lesions after surgery have a measurable impact on outcome. The goal is to understand which residual lesions can be tolerated and which should be addressed prior to leaving the operating room. The Residual Lesion Score study is a large multicentre prospective study designed to evaluate the association of Residual Lesion Score to outcomes in infants undergoing surgery for CHD. This Pediatric Heart Network and National Heart, Lung, and Blood Institute-funded study prospectively enrolled 1,149 infants undergoing 5 different congenital cardiac surgical repairs at 17 surgical centres. Given the contribution of echocardiographic measurements in assigning the Residual Lesion Score, the Residual Lesion Score study made use of a centralised core lab in addition to site review of all data. The data collection plan was designed with the added goal of collecting image quality information in a way that would permit us to improve our understanding of the reproducibility, variability, and feasibility of the echocardiographic measurements being made. There were significant challenges along the way, including the coordination, de-identification, storage, and interpretation of very large quantities of imaging data. This necessitated the development of new infrastructure and technology, as well as use of novel statistical methods. The study was successfully completed, but the size and complexity of the population being studied and the data being extracted required more technologic and human resources than expected which impacted the length and cost of conducting the study. This paper outlines the process of designing and executing this complex protocol, some of the barriers to implementation and lessons to be considered in the design of future studies.

We demonstrate a quasipolynomial-time deterministic approximation algorithm for the partition function of a Gibbs point process interacting via a stable potential. This result holds for all activities $\lambda$ for which the partition function satisfies a zero-free assumption in a neighbourhood of the interval $[0,\lambda ]$. As a corollary, for all finiterange stable potentials, we obtain a quasipolynomial-time deterministic algorithm for all $\lambda \lt 1/(e^{B + 1} \hat C_\phi )$ where $\hat C_\phi$ is a temperedness parameter and $B$ is the stability constant of $\phi$. In the special case of a repulsive potential such as the hard-sphere gas we improve the range of activity by a factor of at least $e^2$ and obtain a quasipolynomial-time deterministic approximation algorithm for all $\lambda \lt e/\Delta _\phi$, where $\Delta _\phi$ is the potential-weighted connective constant of the potential $\phi$. Our algorithm approximates coefficients of the cluster expansion of the partition function and uses the interpolation method of Barvinok to extend this approximation throughout the zero-free region.

We present the third data release from the Parkes Pulsar Timing Array (PPTA) project. The release contains observations of 32 pulsars obtained using the 64-m Parkes ‘Murriyang’ radio telescope. The data span is up to 18 yr with a typical cadence of 3 weeks. This data release is formed by combining an updated version of our second data release with $\sim$3 yr of more recent data primarily obtained using an ultra-wide-bandwidth receiver system that operates between 704 and 4032 MHz. We provide calibrated pulse profiles, flux density dynamic spectra, pulse times of arrival, and initial pulsar timing models. We describe methods for processing such wide-bandwidth observations and compare this data release with our previous release.

We present evidence from a pre-registered experiment indicating that a philosophical argument – a type of rational appeal – can persuade people to make charitable donations. The rational appeal we used follows Singer’s “shallow pond” argument (1972), while incorporating an evolutionary debunking argument (Paxton, Ungar and Greene, 2012) against favoring nearby victims over distant ones. The effectiveness of this rational appeal did not differ significantly from that of a well-tested emotional appeal involving an image of a single child in need (Small, Loewenstein and Slovic, 2007). This is a surprising result, given evidence that emotions are the primary drivers of moral action, a view that has been very influential in the work of development organizations. We found no support for our hypothesis that combining our rational and emotional appeals would have a stronger effect than either appeal in isolation. However, our finding that both kinds of appeal can increase charitable donations is cause for optimism, especially concerning the potential efficacy of well-designed rational appeals. We consider the significance of these findings for moral psychology, ethics, and the work of organizations aiming to alleviate severe poverty.

We present the data and initial results from the first pilot survey of the Evolutionary Map of the Universe (EMU), observed at 944 MHz with the Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The survey covers $270 \,\mathrm{deg}^2$ of an area covered by the Dark Energy Survey, reaching a depth of 25–30 $\mu\mathrm{Jy\ beam}^{-1}$ rms at a spatial resolution of $\sim$ 11–18 arcsec, resulting in a catalogue of $\sim$ 220 000 sources, of which $\sim$ 180 000 are single-component sources. Here we present the catalogue of single-component sources, together with (where available) optical and infrared cross-identifications, classifications, and redshifts. This survey explores a new region of parameter space compared to previous surveys. Specifically, the EMU Pilot Survey has a high density of sources, and also a high sensitivity to low surface brightness emission. These properties result in the detection of types of sources that were rarely seen in or absent from previous surveys. We present some of these new results here.

We describe 14 yr of public data from the Parkes Pulsar Timing Array (PPTA), an ongoing project that is producing precise measurements of pulse times of arrival from 26 millisecond pulsars using the 64-m Parkes radio telescope with a cadence of approximately 3 weeks in three observing bands. A comprehensive description of the pulsar observing systems employed at the telescope since 2004 is provided, including the calibration methodology and an analysis of the stability of system components. We attempt to provide full accounting of the reduction from the raw measured Stokes parameters to pulse times of arrival to aid third parties in reproducing our results. This conversion is encapsulated in a processing pipeline designed to track provenance. Our data products include pulse times of arrival for each of the pulsars along with an initial set of pulsar parameters and noise models. The calibrated pulse profiles and timing template profiles are also available. These data represent almost 21 000 h of recorded data spanning over 14 yr. After accounting for processes that induce time-correlated noise, 22 of the pulsars have weighted root-mean-square timing residuals of $<\!\!1\,\mu\text{s}$ in at least one radio band. The data should allow end users to quickly undertake their own gravitational wave analyses, for example, without having to understand the intricacies of pulsar polarisation calibration or attain a mastery of radio frequency interference mitigation as is required when analysing raw data files.

In recent years, investigations of the phase transition behavior of semiconducting nanoparticles under high pressure has attracted increasing attention due to their potential applications in sensors, electronics, and optics. However, current understanding of how the size of nanoparticles influences this pressure-dependent property is somewhat lacking. In particular, phase behaviors of semiconducting CdS nanoparticles under high pressure have not been extensively reported. Therefore, in this work, CdS nanoparticles of different sizes are used as a model system to investigate particle size effects on high-pressure-induced phase transition behaviors. In particular, 7.5, 10.6, and 39.7 nm spherical CdS nanoparticles are synthesized and subjected to controlled high pressures up to 15 GPa in a diamond anvil cell. Analysis of all three nanoparticles using in-situ synchrotron wide-angle X-ray scattering (WAXS) data shows that phase transitions from wurtzite to rocksalt occur at higher pressures than for bulk material. Bulk modulus calculations not only show that the wurtzite CdS nanomaterial is more compressible than rocksalt, but also that the compressibility of CdS nanoparticles depends on their particle size. Furthermore, sintering of spherical nanoparticles into nanorods was observed for the 7.5 nm CdS nanoparticles. Our results provide new insights into the fundamental properties of nanoparticles under high pressure that will inform designs of new nanomaterial structures for emerging applications.

Direct numerical simulations of two superposed fluids in a channel with a textured surface on the lower wall have been carried out. A parametric study varying the viscosity ratio between the two fluids has been performed to mimic both idealised super-hydrophobic and liquid-infused surfaces and assess its effect on the frictional, form and total drag for three different textured geometries: longitudinal square bars, transversal square bars and staggered cubes. The interface between the two fluids is assumed to be slippery in the streamwise and spanwise directions and not deformable in the vertical direction, corresponding to the ideal case of infinite surface tension. To identify the role of the fluid–fluid interface, an extra set of simulations with a single fluid has been carried out. Comparison with the cases with two fluids reveals the role of the interface in suppressing turbulent transport between the lubricating layer and the overlying flow decreasing the overall drag. In addition, the drag and the maximum wall-normal velocity fluctuations were found to be highly correlated for all the surface configurations, whether they reduce or increase the drag. This implies that the structure of the near-wall turbulence is dominated by the total shear and not by the local boundary condition of the super-hydrophobic, liquid infused or rough surfaces.

Knowledge of the composition of many cultural heritage objects is limited, resulting in many unanswered questions in regards to the provenance, composition, and production methods. In this paper, our objective is to show that dual beam scanning electron microscope (SEM) and focused ion beam (FIB) can be used rapidly and non-destructively to determine the surface and bulk metal compositions in small cultural heritage objects. We show, for the first time, that this novel FIB technique can be successfully applied non-destructively to cultural heritage objects by examining three representative silver plated objects (Candelabra, “Century” spoon, and New York World’s Fair spoon) from the Dallas Museum of Art’s unparalleled collection of modern American silver. In each case, we successfully reveal and characterize the bulk metal as well as the Ag-plating, up to ∼80 µm deep and show that there is no visual damage resulting from the milling process of the FIB. This novel characterization technique can be applied, due to its ease of availability and rapid use, to many other problems in addition to silver plated objects, making dual beam SEM/FIB a possible cornerstone technique in the study of cultural heritage objects.

Clovis sites occur throughout the southwestern United States and northwestern Mexico, but are poorly documented in the central Rio Grande rift region. Here, we present data from two relatively unknown Clovis projectile point assemblages from this region: the first is from the Mockingbird Gap Clovis site and the second is from a survey of the surrounding region. Our goals are to reconstruct general features of the paleoecological adaptation of Clovis populations in the region using raw material sourcing and then to compare the point technology in the region to other Clovis assemblages in the Southwest and across the continent. Our results show that both assemblages were manufactured from similar suites of raw materials that come almost exclusively from the central Rio Grande rift region and the adjacent mountains of New Mexico. Additionally, we show that Clovis projectile points in the study region are significantly smaller than the continental average. Our results suggest that Clovis populations in this region operated within a large, well-known, and relatively high-elevation territory encompassing much of northern and western New Mexico.

Inflammatory bowel disease (IBD) is a collective term for conditions characterised by chronic inflammation of the gastrointestinal tract involving an inappropriate immune response to commensal micro-organisms in a genetically susceptible host. Previously, aqueous and ethyl acetate extracts of gold kiwifruit (Actinidia chinensis) or green kiwifruit (A. deliciosa) have demonstrated anti-inflammatory activity using in vitro models of IBD. The present study examined whether these kiwifruit extracts (KFE) had immune-modulating effects in vivo against inflammatory processes that are known to be increased in patients with IBD. KFE were used as a dietary intervention in IL-10-gene-deficient (Il10− / −) mice (an in vivo model of IBD) and the C57BL/6J background strain in a 3 × 2 factorial design. While all Il10− / − mice developed significant colonic inflammation compared with C57BL/6J mice, this was not affected by the inclusion of KFE in the diet. These findings are in direct contrast to our previous study where KFE reduced inflammatory signalling in primary cells isolated from Il10− / − and C57BL/6J mice. Whole-genome gene and protein expression level profiling indicated that KFE influenced immune signalling pathways and metabolic processes within the colonic tissue; however, the effects were subtle. In particular, expression levels across gene sets related to adaptive immune pathways were significantly reduced using three of the four KFE in C57BL/6J mice. The present study highlights the importance of investigating food components identified by cell-based assays with appropriate in vivo models before making dietary recommendations, as a food that looks promising in vitro may not be effective in vivo.