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To evaluate the potential sources and current screening strategies for the multidrug-resistant fungal pathogen Candida auris in the US Military Health System (MHS).
Methods:
Utilizing the Multidrug-Resistant Organism Repository and Surveillance Network (MRSN), 6 instances of C. auris colonization or infection were identified within the MHS in 2024. Relevant medical and social history, drug susceptibilities, and next-generation genetic sequencing were obtained from MRSN and the electronic medical record. Hospital screening protocols for C. auris were reviewed in the affected facilities.
Results:
One case of C. auris infection and 5 cases of C. auris colonization in 2024 were identified in the MHS. Only 1 case of colonization was likely related to international travel; 5 patients had no recent travel history before infection or colonization. One patient was an active duty service member. Prior hospitalizations and infections were the most common risk factors present in each case. Two isolates had antimicrobial susceptibilities analyzed, both of which suggested resistance to fluconazole. Two of the 3 facilities had C. auris screening protocols in place to screen select individuals with risk factors; however, only 1 of the 6 cases presented was identified through these screening protocols. No cases of nosocomial transmission were found.
Conclusions:
C. auris remains a formidable threat to the MHS, with 6 cases identified in 3 treatment facilities, with 2 isolates demonstrating resistance to azoles. Screening protocols should reflect the domestic and international threats of this pathogen.
Obsessive–compulsive disorder (OCD) is a neuropsychiatric disorder characterized by recurrent intrusive thoughts and ritualized behaviors, often aimed at reducing distress. OCD is heterogeneous in its presentation and many patients with OCD experience a variety of different symptoms throughout their course of illness. Efforts to understand symptom domains in OCD have typically identified three to five symptom domains, such as the domains of doubt/checking, contamination, superstitions/rituals, symmetry/hoarding, and taboo thoughts. Recent studies in the genetics of OCD have suggested a common OCD dimension may provide additional information above and beyond the previously identified symptom domains. Thus, we sought to test a hierarchical model of lifetime OCD symptoms and evaluate the utility of the inclusion of a common OCD dimension.
Methods
Participants included 999 individuals participating in the OCD Collaborative Genetics Study (OCGS) and an additional 2363 individuals participating in the OCD Genetic Association Study (OCGAS). We evaluated unidimensional, 5-factor, and hierarchical models of lifetime OCD symptom presentation using confirmatory factor analysis.
Results
Results suggested that the hierarchical model best fit the data. Further evaluation of these models using a Bayesian testlet response model showed that lifetime presence of specific OCD symptoms was differentially associated with lifetime OCD severity. Moreover, symptoms associated with greater lifetime severity were generally reported less frequently than symptoms present at lower levels of lifetime severity. Implications of these findings and future directions are discussed.
An estimated 93,000 persons were potentially exposed to drinking water contaminated with petroleum jet propellant (JP)-5 fuel after a November 20, 2021, leak at the Red Hill Bulk Fuel Storage Facility on Oahu, Hawaii. Previous investigations identified the need to evaluate long-term mental health effects associated with JP-5 exposure.
Methods
We identified adults potentially exposed to jet fuel-contaminated water during November 20, 2021-March 18, 2022, who sought care within the military health system through February 24, 2023. We abstracted a sample of electronic medical records and categorized documented mental health conditions and symptoms as “worsening preexisting” or “persistent new.” We also assessed mental health-related medication use before and after November 20, 2021.
Results
We abstracted medical charts for 411 adults potentially exposed to jet fuel-contaminated water. Of this cohort, 123 (29.9%) had documented worsening preexisting mental health conditions or symptoms, 86 (20.9%) had persistent new mental health conditions or symptoms, and 109 (26.5%) had at least one mental health-related medication prescribed after the exposure event.
Conclusions
These results highlight mental health needs during and after water contamination events. Continued access to mental health care services and monitoring for long-term mental health effects is recommended.
On November 20, 2021, petroleum fuel contaminated the Red Hill well, which provides water to about 93 000 persons on Oahu, Hawaii. Initial investigations recommended further evaluations of long-term health effects of petroleum exposure in drinking water. We reviewed electronic health records of those potentially exposed to contaminated water to understand prevalence of conditions and symptoms.
Methods
A sample of persons potentially exposed during November 20, 2021-March 18, 2022 who sought care within the military health system through February 24, 2023 was identified. Abstracted records were categorized as worsening preexisting or persistent new for conditions and symptoms.
Results
Of 653 medical charts reviewed, 357 (55%) had worsening preexisting or persistent new conditions or symptoms. Most-documented conditions included worsening preexisting migraine (8%; 50/653) and chronic pain (4%; 26/653), and persistent new migraine (2%; 14/653) and adjustment disorder (2%; 13/653). Most-documented symptoms included worsening preexisting headache (8%; 49/653) and anxiety (6%; 42/653), and persistent new rash (7%; 46/653) and headache (5%; 34/653).
Conclusions
Approximately half of the abstracted medical records demonstrated worsening preexisting or persistent new conditions or symptoms and might benefit from sustained access to physical, mental, and specialized health care support systems. Continued monitoring for long-term health outcomes is recommended.
Patients with posttraumatic stress disorder (PTSD) exhibit smaller regional brain volumes in commonly reported regions including the amygdala and hippocampus, regions associated with fear and memory processing. In the current study, we have conducted a voxel-based morphometry (VBM) meta-analysis using whole-brain statistical maps with neuroimaging data from the ENIGMA-PGC PTSD working group.
Methods
T1-weighted structural neuroimaging scans from 36 cohorts (PTSD n = 1309; controls n = 2198) were processed using a standardized VBM pipeline (ENIGMA-VBM tool). We meta-analyzed the resulting statistical maps for voxel-wise differences in gray matter (GM) and white matter (WM) volumes between PTSD patients and controls, performed subgroup analyses considering the trauma exposure of the controls, and examined associations between regional brain volumes and clinical variables including PTSD (CAPS-4/5, PCL-5) and depression severity (BDI-II, PHQ-9).
Results
PTSD patients exhibited smaller GM volumes across the frontal and temporal lobes, and cerebellum, with the most significant effect in the left cerebellum (Hedges’ g = 0.22, pcorrected = .001), and smaller cerebellar WM volume (peak Hedges’ g = 0.14, pcorrected = .008). We observed similar regional differences when comparing patients to trauma-exposed controls, suggesting these structural abnormalities may be specific to PTSD. Regression analyses revealed PTSD severity was negatively associated with GM volumes within the cerebellum (pcorrected = .003), while depression severity was negatively associated with GM volumes within the cerebellum and superior frontal gyrus in patients (pcorrected = .001).
Conclusions
PTSD patients exhibited widespread, regional differences in brain volumes where greater regional deficits appeared to reflect more severe symptoms. Our findings add to the growing literature implicating the cerebellum in PTSD psychopathology.
A key step toward understanding psychiatric disorders that disproportionately impact female mental health is delineating the emergence of sex-specific patterns of brain organisation at the critical transition from childhood to adolescence. Prior work suggests that individual differences in the spatial organisation of functional brain networks across the cortex are associated with psychopathology and differ systematically by sex.
Aims
We aimed to evaluate the impact of sex on the spatial organisation of person-specific functional brain networks.
Method
We leveraged person-specific atlases of functional brain networks, defined using non-negative matrix factorisation, in a sample of n = 6437 youths from the Adolescent Brain Cognitive Development Study. Across independent discovery and replication samples, we used generalised additive models to uncover associations between sex and the spatial layout (topography) of personalised functional networks (PFNs). We also trained support vector machines to classify participants’ sex from multivariate patterns of PFN topography.
Results
Sex differences in PFN topography were greatest in association networks including the frontoparietal, ventral attention and default mode networks. Machine learning models trained on participants’ PFNs were able to classify participant sex with high accuracy.
Conclusions
Sex differences in PFN topography are robust, and replicate across large-scale samples of youth. These results suggest a potential contributor to the female-biased risk in depressive and anxiety disorders that emerge at the transition from childhood to adolescence.
We present the Evolutionary Map of the Universe (EMU) survey conducted with the Australian Square Kilometre Array Pathfinder (ASKAP). EMU aims to deliver the touchstone radio atlas of the southern hemisphere. We introduce EMU and review its science drivers and key science goals, updated and tailored to the current ASKAP five-year survey plan. The development of the survey strategy and planned sky coverage is presented, along with the operational aspects of the survey and associated data analysis, together with a selection of diagnostics demonstrating the imaging quality and data characteristics. We give a general description of the value-added data pipeline and data products before concluding with a discussion of links to other surveys and projects and an outline of EMU’s legacy value.
The stars of the Milky Way carry the chemical history of our Galaxy in their atmospheres as they journey through its vast expanse. Like barcodes, we can extract the chemical fingerprints of stars from high-resolution spectroscopy. The fourth data release (DR4) of the Galactic Archaeology with HERMES (GALAH) Survey, based on a decade of observations, provides the chemical abundances of up to 32 elements for 917 588 stars that also have exquisite astrometric data from the Gaia satellite. For the first time, these elements include life-essential nitrogen to complement carbon, and oxygen as well as more measurements of rare-earth elements critical to modern-life electronics, offering unparalleled insights into the chemical composition of the Milky Way. For this release, we use neural networks to simultaneously fit stellar parameters and abundances across the whole wavelength range, leveraging synthetic grids computed with Spectroscopy Made Easy. These grids account for atomic line formation in non-local thermodynamic equilibrium for 14 elements. In a two-iteration process, we first fit stellar labels to all 1 085 520 spectra, then co-add repeated observations and refine these labels using astrometric data from Gaia and 2MASS photometry, improving the accuracy and precision of stellar parameters and abundances. Our validation thoroughly assesses the reliability of spectroscopic measurements and highlights key caveats. GALAH DR4 represents yet another milestone in Galactic archaeology, combining detailed chemical compositions from multiple nucleosynthetic channels with kinematic information and age estimates. The resulting dataset, covering nearly a million stars, opens new avenues for understanding not only the chemical and dynamical history of the Milky Way but also the broader questions of the origin of elements and the evolution of planets, stars, and galaxies.
This study uses stable and radiogenic isotopic data from Chalcolithic (c. 3000–1900 bc) humans and animals recovered from the Rego da Murta dolmens (Alvaiázere, Portugal) to understand dietary and mobility patterns in the populations using these monuments. The results suggest diets based primarily on C3 plants and terrestrial animals, with some possible variation in protein intake by age or status. Analyses of 87Sr/86Sr values identify two individuals out of ten from Rego da Murta I and four individuals out of fifteen from Rego da Murta II as migrants. These data were compared to other Chalcolithic burials in south-western Portugal: while diets were found to be similar across the region, the very high 87Sr/86Sr values recorded for two migrant humans match no known settlement in the broader region. A recent mapping study of 87Sr/86Sr values in Portugal suggests their origins may lie to the north/north-east of the dolmens.
To measure SARS-CoV-2 anti-nucleocapsid (anti-N) antibody seropositivity among healthcare personnel (HCP) without a history of COVID-19 and to identify HCP characteristics associated with seropositivity.
Design:
Prospective cohort study from September 22, 2020, to March 3, 2022.
Setting:
A tertiary care academic medical center.
Participants:
727 HCP without prior positive SARS-CoV-2 PCR testing were enrolled; 559 HCP successfully completed follow-up.
Methods:
At enrollment and follow-up 1–6 months later, HCP underwent SARS-CoV-2 anti-N testing and were surveyed on demographics, employment information, vaccination status, and COVID-19 symptoms and exposures.
Results:
Of 727 HCP enrolled, 27 (3.7%) had a positive SARS-CoV-2 anti-N test at enrollment. Seropositive HCPs were more likely to have a household exposure to COVID-19 in the past 30 days (OR 7.92, 95% CI 2.44–25.73), to have had an illness thought to be COVID-19 (4.31, 1.94–9.57), or to work with COVID-19 patients more than half the time (2.09, 0.94–4.77). Among 559 HCP who followed-up, 52 (9.3%) had a positive SARS-CoV-2 anti-N antibody test result. Seropositivity at follow-up was associated with community/household exposures to COVID-19 within the past 30 days (9.50, 5.02–17.96; 2.90, 1.31–6.44), having an illness thought to be COVID-19 (8.24, 4.44–15.29), and working with COVID-19 patients more than half the time (1.50, 0.80–2.78).
Conclusions:
Among HCP without prior positive SARS-CoV-2 testing, SARS-CoV-2 anti-N seropositivity was comparable to that of the general population and was associated with COVID-19 symptomatology and both occupational and non-occupational exposures to COVID-19.
A clinical tool to estimate the risk of treatment-resistant schizophrenia (TRS) in people with first-episode psychosis (FEP) would inform early detection of TRS and overcome the delay of up to 5 years in starting TRS medication.
Aims
To develop and evaluate a model that could predict the risk of TRS in routine clinical practice.
Method
We used data from two UK-based FEP cohorts (GAP and AESOP-10) to develop and internally validate a prognostic model that supports identification of patients at high-risk of TRS soon after FEP diagnosis. Using sociodemographic and clinical predictors, a model for predicting risk of TRS was developed based on penalised logistic regression, with missing data handled using multiple imputation. Internal validation was undertaken via bootstrapping, obtaining optimism-adjusted estimates of the model's performance. Interviews and focus groups with clinicians were conducted to establish clinically relevant risk thresholds and understand the acceptability and perceived utility of the model.
Results
We included seven factors in the prediction model that are predominantly assessed in clinical practice in patients with FEP. The model predicted treatment resistance among the 1081 patients with reasonable accuracy; the model's C-statistic was 0.727 (95% CI 0.723–0.732) prior to shrinkage and 0.687 after adjustment for optimism. Calibration was good (expected/observed ratio: 0.999; calibration-in-the-large: 0.000584) after adjustment for optimism.
Conclusions
We developed and internally validated a prediction model with reasonably good predictive metrics. Clinicians, patients and carers were involved in the development process. External validation of the tool is needed followed by co-design methodology to support implementation in early intervention services.
Digital Mental Health Interventions (DMHIs) that meet the definition of a medical device are regulated by the Medicines and Healthcare products Regulatory Agency (MHRA) in the UK. The MHRA uses procedures that were originally developed for pharmaceuticals to assess the safety of DMHIs. There is recognition that this may not be ideal, as is evident by an ongoing consultation for reform led by the MHRA and the National Institute for Health and Care Excellence.
Aims
The aim of this study was to generate an experts’ consensus on how the medical regulatory method used for assessing safety could best be adapted for DMHIs.
Method
An online Delphi study containing three rounds was conducted with an international panel of 20 experts with experience/knowledge in the field of UK digital mental health.
Results
Sixty-four items were generated, of which 41 achieved consensus (64%). Consensus emerged around ten recommendations, falling into five main themes: Enhancing the quality of adverse events data in DMHIs; Re-defining serious adverse events for DMHIs; Reassessing short-term symptom deterioration in psychological interventions as a therapeutic risk; Maximising the benefit of the Yellow Card Scheme; and Developing a harmonised approach for assessing the safety of psychological interventions in general.
Conclusion
The implementation of the recommendations provided by this consensus could improve the assessment of safety of DMHIs, making them more effective in detecting and mitigating risk.
Development and Psychopathology has been a premier resource for understanding stressful childhood experiences and the intergenerational continuity of psychopathology. Building on that tradition, we examined the unique and joint influences of maternal stress on children’s effortful control (age 7) and externalizing behavior (age 11) as transmitted via genetics, the prenatal environment, and the postnatal environment. The sample included N = 561 adopted children and their biological and adoptive parents. Path models identified a direct effect of biological mother life stress on children’s effortful control (β = −.08) and an indirect effect of her life stress on child externalizing behavior via effortful control (β = .52), but no main or indirect effects of biological parent psychopathology, prenatal stress, or adoptive mother adverse childhood experiences (ACES). Adoptive mother ACES amplified the association between biological mother life stress and child effortful control (β = −.08), externalizing behavior (β = 1.41), and the indirect effect via effortful control, strengthening associations when adoptive mothers reported average or high ACES during their own childhoods. Results suggest that novel study designs are needed to enhance the understanding of how life stress gets “under the skin” to affect psychopathology in the offspring of adults who have experienced stress.
Translation is the process of turning observations in the research laboratory, clinic, and community into interventions that improve people’s health. The Clinical and Translational Science Awards (CTSA) program is a National Center for Advancing Translational Sciences (NCATS) initiative to advance translational science and research. Currently, 64 “CTSA hubs” exist across the nation. Since 2006, the Houston-based Center for Clinical Translational Sciences (CCTS) has assembled a well-integrated, high-impact hub in Texas that includes six partner institutions within the state, encompassing ∼23,000 sq. miles and over 16 million residents. To achieve the NCATS goal of “more treatments for all people more quickly,” the CCTS promotes diversity and inclusion by integrating underrepresented populations into clinical studies, workforce training, and career development. In May 2023, we submitted the UM1 application and six “companion” proposals: K12, R25, T32-Predoctoral, T32-Postdoctoral, and RC2 (two applications). In October 2023, we received priority scores for the UM1 (22), K12 (25), T32-Predoctoral (20), and T32-Postdoctoral (23), which historically fall within the NCATS funding range. This report describes the grant preparation and submission approach, coupled with data from an internal survey designed to assimilate feedback from principal investigators, writers, reviewers, and administrative specialists. Herein, we share the challenges faced, the approaches developed, and the lessons learned.
Individuals tend to overestimate their abilities in areas where they are less competent. This cognitive bias is known as the Dunning-Krueger effect. Research shows that Dunning-Krueger effect occurs in persons with traumatic brain injury and healthy comparison participants. It was suggested by Walker and colleagues (2017) that the deficits in cognitive awareness may be due to brain injury. Confrontational naming tasks (e.g., Boston Naming Test) are used to evaluate language abilities. The Cordoba Naming Test (CNT) is a 30-item confrontational naming task developed to be administered in multiple languages. Hardy and Wright (2018) conditionally validated a measure of perceived mental workload called the NASA Task Load Index (NASA-TLX). They found that workload ratings on the NASA-TLX increased with increased task demands on a cognitive task. The purpose of the present study was to determine whether the Dunning-Kruger effect occurs in a Latinx population and possible factors driving individuals to overestimate their abilities on the CNT. We predicted the low-performance group would report better CNT performance, but underperform on the CNT compared to the high-performance group.
Participants and Methods:
The sample consisted of 129 Latinx participants with a mean age of 21.07 (SD = 4.57). Participants were neurologically and psychologically healthy. Our sample was divided into two groups: the low-performance group and the high-performance group. Participants completed the CNT and the NASA-TLX in English. The NASA-TLX examines perceived workload (e.g., performance) and it was used in the present study to evaluate possible factors driving individuals to overestimate their abilities on the CNT. Participants completed the NASA-TLX after completing the CNT. Moreover, the CNT raw scores were averaged to create the following two groups: low-performance (CNT raw score <17) and high-performance (CNT raw score 18+). A series of ANCOVA's, controlling for gender and years of education completed were used to evaluate CNT performance and CNT perceived workloads.
Results:
We found the low-performance group reported better performance on the CNT compared to the high-performance, p = .021, np2 = .04. However, the high-performance group outperformed the low-performance group on the CNT, p = .000, np2 = .53. Additionally, results revealed the low-performance group reported higher temporal demand and effort levels on the CNT compared to the high-performance group, p's < .05, nps2 = .05.
Conclusions:
As we predicted, the low-performance group overestimated their CNT performance compared to the high-performance group. The current data suggest that the Dunning-Kruger effect occurs in healthy Latinx participants. We also found that temporal demand and effort may be influencing awareness in the low-performance group CNT performance compared to the high-performance group. The present study suggests subjective features on what may be influencing confrontational naming task performance in low-performance individuals more than highperformance individuals on the CNT. Current literature shows that bilingual speakers underperformed on confrontational naming tasks compared to monolingual speakers. Future studies should investigate if the Dunning-Kruger effects Latinx English monolingual speakers compared to Spanish-English bilingual speakers on the CNT.
The Cordoba Naming Test (CNT) is a 30-item lexical retrieval task that was developed to be administered in multiple languages. Research shows that self-identifying Mexicans residing in Mexico outperform self-identifying Mexicans that reside in the United States on the CNT. Studies indicate that the process of acculturation can influence cognitive performance. Previous studies demonstrated that Generation Z individuals (i.e., people born between 1997 and 2012) have underperformed on the CNT compared to Generation Y individuals (i.e., people born between 1981 and 1996). To our knowledge, no study has examined the influence of acculturation on Generation Z Mexicans’ CNT performance. We expected Mexicans residing in Mexico (MRM) to outperform Mexicans residing in the United States on the CNT and to report higher acculturation traits. We also predicted that acculturation would correlate with CNT performance.
Participants and Methods:
The present study sample consisted of 285 Generation Z psychologically and neurologically healthy Mexicans with a mean age of 20.32 (SD = 1.60). Participants were divided into three groups: MRM, Mexicans residing in the United States, and Mexican-Americans residing in the United States (MARUS). All participants completed the CNT and acculturation measure in Spanish. Acculturation traits were measured by the Abbreviated Multidimensional Acculturation Scale (AMAS). ANCOVAs were used to evaluate differences in the CNT and AMAS (i.e., Spanish language, Latino competency, Latino identity). Pearson’s correlation coefficient was used to evaluate the relationship between acculturation on CNT performance.
Results:
MRM outperformed the Mexicans residing in the United States and MARUS on the CNT, p = .000, np2 = .49. The MRM group reported better Spanish language abilities compared to Mexicans residing in the United States and the MARUS groups, p = .000, np2 = .10. Additionally, MRM reported better Latino competency than the MARUS group, p = .000, np2 = .08. Pearson’s correlation coefficient revealed that the MARUS’s Spanish language abilities impacted CNT performance, p = .000, r = .48. In addition, we found that Latino competency correlated with CNT performance, p’s < .05, r’s = .20-.47, in both the MRM and Mexicans residing in the United States groups. Latino identity did not significantly correlate with CNT performance in any group.
Conclusions:
Results confirmed that MRM individuals perform better on the CNT than Mexicans residing in the United States and MARUS. Additionally, we found that several acculturation traits correlated with Mexican groups’ CNT performance. Our research indicates that while all Generation Z individuals of Mexican heritage feel strongly connected to their Latino identity regardless of where they live, MARUS feel less competent in Spanish and Latinx culture than MRM and Mexicans residing in the United States. Future work should further explore these differences for better insight into how acculturative factors influence lexical retrieval performance. Future work with bigger sample sizes can additionally examine CNT performance and acculturation in Generation Z first-generation and non-first-generation Mexicans (e.g., second-generation, third-generation) residing in the United States.
This work investigates the effect of surface roughness on cylinder flows in the postcritical regime and reexamines whether the roughness Reynolds number ($Re_{k_s}$) primarily governs the aerodynamic behaviour. It has been motivated by limitations of many previous investigations, containing occasionally contradictory findings. In particular, many past studies were conducted with relatively high blockage ratios and low cylinder aspect ratios. Both of these factors appear to have non-negligible effects on flow behaviour, and particularly fluctuating quantities such as the standard deviation of the lift coefficient. This study employs a 5 % blockage ratio and a span-to-diameter ratio of 10. Cylinders of different relative surface roughness ratios ($k_s/D$), ranging from $1.1\times 10^{-3}$ to $3\times 10^{-3}$, were investigated at Reynolds numbers up to $6.8 \times 10^5$ and $Re_{k_s}$ up to 2200. It is found that the base pressure coefficient, drag coefficient, Strouhal number, spanwise correlation length of lift and the standard deviation of the lift coefficient are well described by $Re_{k_s}$ in postcritical flows. However, roughness does have an effect on the minimum surface pressure coefficient (near separation) that does not collapse with $Re_{k_s}$. The universal Strouhal number proposed by Bearman (Annu. Rev. Fluid Mech., vol. 16, 1984, pp. 195–222) appears to be nearly constant over the range of $Re_{k_s}$ studied, spanning the subcritical through postcritical regimes. Frequencies in the separating shear layers are found to be an order of magnitude lower than the power law predictions for separating shear layers of smooth cylinders.
In this brief communication, we discuss the current landscape and unmet needs of pediatric to adult transition care in neurology. Optimizing transition care is a priority for patients, families, and providers with growing discussion in neurology. We also introduce the activities of the University of Toronto Pediatric-Adult Transition Working Group – a collaborative interdivisional and inter-subspeciality group of faculty, advanced-practice providers, trainees, and patient-family advisors pursuing collaboration with patients, families, and universities from across Canada. We envision that these efforts will result in a national neurology transition strategy that will inform designation of health authority attention and funding.
We recently reported on the radio-frequency attenuation length of cold polar ice at Summit Station, Greenland, based on bi-static radar measurements of radio-frequency bedrock echo strengths taken during the summer of 2021. Those data also allow studies of (a) the relative contributions of coherent (such as discrete internal conducting layers with sub-centimeter transverse scale) vs incoherent (e.g. bulk volumetric) scattering, (b) the magnitude of internal layer reflection coefficients, (c) limits on signal propagation velocity asymmetries (‘birefringence’) and (d) limits on signal dispersion in-ice over a bandwidth of ~100 MHz. We find that (1) attenuation lengths approach 1 km in our band, (2) after averaging 10 000 echo triggers, reflected signals observable over the thermal floor (to depths of ~1500 m) are consistent with being entirely coherent, (3) internal layer reflectivities are ≈–60$\to$–70 dB, (4) birefringent effects for vertically propagating signals are smaller by an order of magnitude relative to South Pole and (5) within our experimental limits, glacial ice is non-dispersive over the frequency band relevant for neutrino detection experiments.