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Measurements of suspended sediment volume concentrations, particle size and number density are routinely collected in marine and fresh‐water environments with LISST‐100X instruments to understand sediment transport, biological processes and fundamental opto‐acoustic problems. A LISST‐100X was simultaneously deployed with a novel holographic camera (holocam) in UK coastal waters to assess the performance of the laser diffraction technique when measuring natural suspensions. Volume distributions from the LISST‐100X, truncated to exclude non‐overlapping size bins with the holocam, exhibit an increase in small particles and median particle size is elevated in comparison to the holocam by 20–40%. We observe positive offsets between LISST‐100X and holocam number distributions of up to 2 orders of magnitude for particle sizes between 58–218μm, with discrepancies rising to 4 orders of magnitude for finer and coarser sizes. To explain these differences, a novel multiscale representation of particle size is used. The method quantifies individual dimensions that make up any two‐dimensional geometrical structure, it can be used as a metric for particle complexity, and offers a plausible explanation for an apparent increase in small particles (<58μm) reported by the LISST‐100X. The results suggest that for non‐spherical natural suspensions the LISST‐100X may be sensitive to optical scattering from sub‐scales within larger particles, reporting them as individual particles regardless of the way in which they may be packaged into particles of larger overall size. We urge caution in over interpretation of LISST size distributions obtained in natural suspensions without verification with independent particle imaging. Key Points Comparison of LISST‐100X and submersible holocam particle size distributions Observation of discrepancy between LISST‐100X and holocam number concentrations Using circle packing methodology to infer impact of optical scatterers on LISST

The sequence of events associated with the triggering of energy release during substorm expansion phase onset is still not well‐understood. Oberhagemann and Mann (2020b, https://doi.org/10.1029/2019gl085271) proposed a new substorm onset mechanism, where the transition toward parallel proton pressure anisotropy during tail stretching in the late growth phase could trigger a pressure anisotropic ballooning instability. Here we examine the evolution of energetic proton parallel pressure anisotropy at geosynchronous altitudes, seeking evidence in support of the proposed substorm onset mechanism. We use the Geostationary Operational Environment Satellite (GOES) proton flux and magnetometer data combined with substorm onset indicators derived from ground‐based magnetometers. Superposed epoch analysis of substorm onset times for 2014 using the isolated substorm list (Ohtani & Gjerloev, 2020, https://doi.org/10.1029/2020ja027902) clearly shows signatures of energetic proton parallel pressure anisotropy immediately before substorm onset, potentially supportive of the Oberhagemann and Mann theory. Plain Language Summary Substorms are disturbances in the nightside region of the geospace associated with the rapid release of stored magnetic energy. In the ionosphere, the signatures of this energy release are the spectacular dancing lights known as aurorae (northern and southern lights). The processes that lead to energy storage are well‐known. However, there are competing theories on what triggers the release of this significant amount of energy at substorm onset. According to a new substorm onset theory proposed by Oberhagemann and Mann, when the magnetic field stretches in the nightside during the energy storage, the pressure becomes more parallel to the magnetic field, leading to a ballooning instability at substorm onset. Here, we look for observational support for the association of such pressure profile at geosynchronous altitudes with substorm onset to examine the proposed model. Superposed epoch analysis of isolated substorms in 2014 shows increasing energetic proton parallel pressure anisotropy at the onset, providing evidence to support the Oberhagemann and Mann theory. Key Points Oberhagemann and Mann theory proposes that proton parallel temperature anisotropy triggers ballooning instability leading to substorm onset We use pitch angle resolved energetic proton fluxes at geosynchronous altitudes seeking observational evidence in support of the model Superposed epoch analysis of isolated substorms shows signatures of increasing energetic proton parallel anisotropy which peaks near onset

While cytosine methylation has been widely studied in extant populations, relatively few studies have analyzed methylation in ancient DNA. Most existing studies of epigenetic marks in ancient DNA have inferred patterns of methylation in highly degraded samples using post-mortem damage to cytosines as a proxy for cytosine methylation levels. However, this approach limits the inference of methylation compared with direct bisulfite sequencing, the current gold standard for analyzing cytosine methylation at single nucleotide resolution. In this study, we used direct bisulfite sequencing to assess cytosine methylation in ancient DNA from the skeletal remains of 30 Native Americans ranging in age from approximately 230 to 4500 years before present. Unmethylated cytosines were converted to uracils by treatment with sodium bisulfite, bisulfite products of a CpG-rich retrotransposon were pyrosequenced, and C-to-T ratios were quantified for a single CpG position. We found that cytosine methylation is readily recoverable from most samples, given adequate preservation of endogenous nuclear DNA. In addition, our results indicate that the precision of cytosine methylation estimates is inversely correlated with aDNA preservation, such that samples of low DNA concentration show higher variability in measures of percent methylation than samples of high DNA concentration. In particular, samples in this study with a DNA concentration above 0.015 ng/μL generated the most consistent measures of cytosine methylation. This study presents evidence of cytosine methylation in a large collection of ancient human remains, and indicates that it is possible to analyze epigenetic patterns in ancient populations using direct bisulfite sequencing approaches.

Measurements of turbulence and suspended particle characteristics have been made continuously for 9 tidal cycles in a shallow, energetic tidal channel. Particle‐size spectra were measured with a LISST‐100 laser diffraction instrument placed on a frame on the seabed. A 1200 kHz ADCP in the same frame was used to measure vertical current profiles and from these the turbulent kinetic energy dissipation rate was determined using the structure function method. Median particle size is observed to change in a regular way by a factor of 3 or more over each tidal cycle, with the largest particles observed at slack tide and the smallest at times of maximum flood and ebb. The most likely explanation of this change is that particles are aggregating at times of low turbulence and breaking up during fast flows. A simple dynamical flocculation model that incorporates these processes gives good agreement with observations, particularly if tidal advection of a longitudinal gradient in particle size is allowed for. If particles have time to reach equilibrium with ambient conditions, the model predicts that the particle size will be proportional to the product of concentration and the Kolmogorov microscale. The observations support this prediction on most tidal cycles if a phase lag (of 30–60 min) is allowed between the measurements of particle size and Kolmogorov scale. This phase lag represents the adjustment time for flocs to respond to change in turbulence. The constant of proportionality between median particle size and Kolmogorov scale increases with particle volume. Key Points Observations of floc size and turbulence are presented A dynamical model reproduces the observations For some of the time, floc size is proportional to Kolmogorov scale, with a lag

Changes in the Earth's geomagnetic field induce geoelectric fields in the solid Earth. These electric fields drive Geomagnetically Induced Currents (GICs) in grounded, conducting infrastructure. These GICs can damage or degrade equipment if they are sufficiently intense—understanding and forecasting them is of critical importance. One of the key magnetospheric phenomena are Sudden Commencements (SCs). To examine the potential impact of SCs we evaluate the correlation between the measured maximum GICs and rate of change of the magnetic field (H′) in 75 power grid transformers across New Zealand between 2001 and 2020. The maximum observed H′ and GIC correlate well, with correlation coefficients (r2) around 0.7. We investigate the gradient of the relationship between H′ and GIC, finding a hot spot close to Dunedin: where a given H′ will drive the largest relative current (0.5 A nT−1 min). We observe strong intralocation variability, with the gradients varying by a factor of two or more at adjacent transformers. We find that GICs are (on average) greater if they are related to: (a) Storm Sudden Commencements (SSCs; 27% larger than Sudden Impulses, SIs); (b) SCs while New Zealand is on the dayside of the Earth (27% larger than the nightside); and (c) SCs with a predominantly East‐West magnetic field change (14% larger than North‐South equivalents). These results are attributed to the geology of New Zealand and the geometry of the power network. We extrapolate to find that transformers near Dunedin would see 2000 A or more during a theoretical extreme SC (H′ = 4000 nT min−1).

Geomagnetically Induced Currents (GICs) are a severe space weather hazard, driven through coupling between the solar wind and magnetosphere. GICs are rarely measured directly, instead the ground magnetic field variability is often used as a proxy. Recently space weather models have been developed to forecast whether the magnetic field variability (R) will exceed specific, extreme thresholds. We test an example machine learning‐based model developed for the northern United Kingdom. We evaluate its performance (discriminative skill and calibration) as a function of magnetospheric state, solar wind input and magnetic local time. We find that the model's performance is highest during active conditions, for example, geomagnetic storms, and lowest during isolated substorms and “quiet” intervals, despite these conditions dominating the training data set. Correspondingly, the performance is high when the solar wind conditions are elevated (i.e., high velocity, large total magnetic field strength, and the interplanetary magnetic field oriented southward), and at a minimum when the north‐south component of the magnetic field is highly variable or around zero. Regarding magnetic local time, performance is highest within the dusk and night sectors, and lowest during the day. The model appears to capture multiple modes of magnetospheric activity, including substorms and viscous interactions, but poorly predicts impulsive phenomena (i.e., storm sudden commencements) and longer timescale coupling processes. Future models of mid‐latitude magnetic field variability will need to effectively use longer time intervals of unpropagated (i.e., observations from L1) solar wind to more completely describe the magnetospheric conditions and response.

Understanding global space weather effects is of great importance to the international scientific community, but more localized space weather predictions are important on a national level. In this study, data from a ground magnetometer at Valentia Observatory is used to characterize space weather effects on the island of Ireland. The horizontal component of magnetometer observations and its time derivative are considered, and extreme values of these are identified. These extremes are fit to a generalized extreme value distribution, and from this model return values (the expected magnitude of an observation within a given time window) are predicted. The causes of extreme values are investigated both in a case study, and also statistically by looking at contributions from geomagnetic storms, substorms, and sudden commencements. This work characterizes the extreme part of the distribution of space weather effects on Ireland (and at similar latitudes), and hence examines those space weather observations which are likely to have the greatest impact on susceptible technologies.

This paper extends recent research on vehicles with hydraulically interconnected suspension (HIS) systems. Such suspension schemes have received considerable attention in the research community over the last few years. This is due, in part, to their reported ability to provide stiffness and damping rates dependent on the suspension mode of operation (i.e. the bounce, roll, pitch, or articulation of the unsprung masses relative to the sprung mass), rather than relying on the stiffness and damping characteristics of the single wheel stations. In this paper, the optimization of such a system is considered. Use is made of a previously derived four-degree-of-freedom model of a roll-plane half-car fitted with a typical antiroll HIS system. Objective functions are then developed, based on the desire to improve ride comfort and to minimize suspension working space and tyre normal force fluctuations. With this formulation, a large number of optimal solutions are found and presented graphically, and the performance limitations and trade-offs between the desired objectives are illustrated. To contextualize these results, a similar optimization process is applied to a half-car with a conventional independent suspension. Four optimal parameter combinations are then selected as base points for further examination of the HIS vehicle. This is done by way of a basic sensitivity analysis, based on the local method, which involves single-parameter perturbations about a base point. The objective of the paper is to outline the dynamic performance, trade-offs, and limitations of an HIS-equipped vehicle, and to identify the system's most important parameters.

Background:Conjoint analysis involves the measurement of consumer preferences between choice alternatives.Aims and objectives:To investigate the use of conjoint analysis in facilitating and understanding choice of growth hormone injection devices.Method and subjects:56 patients and their parents participated in an electronic, computer-based interview. The interview took a median time of 18 min (range 12–30) and allowed an immediate matching of injection devices to the family’s preferences.Results:Amongst the key drivers of choice, lack of bruising was rated highest and designated an index of 100. Compared to this, the remaining attributes in order of desirability were: auto-injector (98), lack of pain (93), lightweight (88), silent (82), ready-mixed (77), ease of holding (69), telephone helpline (66), needle-free (62), small size (60), nurse support (47), hidden needle (45), stored in fridge (13) and home delivery (6). Out of the 17 families who had already chosen a device previously by discussion with the clinic nurse, the computer model placed their device either as first or second out of seven devices tested.Conclusion:Adaptive or interactive conjoint analysis applied at the patient level can facilitate the choice-making process whilst providing an insight into the relative importance of the key features that influence choice.

OBJECTIVE: To investigate the effects of chronic stress on weight changes and related behavioral changes in parents with a child who had just been diagnosed with cancer compared to parents with healthy children. DESIGN: Longitudinal case–control study with assessments occurring over a three-month period following the child's diagnosis of cancer. SUBJECTS: In total, 49 parents of healthy children and 49 parents of cancer patients aged 19–58 y. MEASUREMENTS: Body weight, diet, physical activity, self-reported mood and stress. RESULTS: Parents of cancer patients were more likely to gain weight, and experienced significantly greater weight gain over the 3 months than parents of healthy children. The magnitude of weight gain was related to the degree of psychological distress that the parents experienced. Parents of cancer patients reported lower levels of physical activity and lower caloric intake than parents of healthy children, with the most marked differences between groups occurring in the area of physical activity. CONCLUSION: Findings suggest that a major stressor, such as a child's diagnosis of cancer, is associated with weight gain. Further research is needed to determine how long these weight gains persist and whether other types of stress also produce weight gains. Such studies should focus not only on the effect of stress on eating behavior but also on physical activity.