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Foliar-applied postemergence applications of glufosinate are often applied to glufosinate-resistant crops to provide nonselective weed control without significant crop injury. Rainfall, air temperature, solar radiation, and relative humidity near the time of application have been reported to affect glufosinate efficacy. However, previous research may have not captured the full range of weather variability to which glufosinate may be exposed before or following application. Additionally, climate models suggest more extreme weather will become the norm, further expanding the weather range to which glufosinate can be exposed. The objective of this research was to quantify the probability of successful weed control (efficacy ≥85%) with glufosinate applied to some key weed species across a broad range of weather conditions. A database of >10,000 North American herbicide evaluation trials was used in this study. The database was filtered to include treatments with a single postemergence application of glufosinate applied to waterhemp [Amaranthus tuberculatus (Moq.) Sauer], morningglory species (Ipomoea spp.), and/or giant foxtail (Setaria faberi Herrm.) <15 cm in height. These species were chosen because they are well represented in the database and listed as common and troublesome weed species in both corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] (Van Wychen 2020, 2022). Individual random forest models were created. Low rainfall (≤20 mm) over the 5 d before glufosinate application was detrimental to the probability of successful control of A. tuberculatus and S. faberi. Lower relative humidity (≤70%) and solar radiation (≤23 MJ m−1 d−1) on the day of application reduced the probability of successful weed control in most cases. Additionally, the probability of successful control decreased for all species when average air temperature over the first 5 d after application was ≤25 C. As climate continues to change and become more variable, the risk of unacceptable control of several common species with glufosinate is likely to increase.
Foliar-applied postemergence herbicides are a critical component of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] weed management programs in North America. Rainfall and air temperature around the time of application may affect the efficacy of herbicides applied postemergence in corn or soybean production fields. However, previous research utilized a limited number of site-years and may not capture the range of rainfall and air temperatures that these herbicides are exposed to throughout North America. The objective of this research was to model the probability of achieving successful weed control (≥85%) with commonly applied postemergence herbicides across a broad range of environments. A large database of more than 10,000 individual herbicide evaluation field trials conducted throughout North America was used in this study. The database was filtered to include only trials with a single postemergence application of fomesafen, glyphosate, mesotrione, or fomesafen + glyphosate. Waterhemp [Amaranthus tuberculatus (Moq.) Sauer], morningglory species (Ipomoea spp.), and giant foxtail (Setaria faberi Herrm.) were the weeds of focus. Separate random forest models were created for each weed species by herbicide combination. The probability of successful weed control deteriorated when the average air temperature within the first 10 d after application was <19 or >25 C for most of the herbicide by weed species models. Additionally, drier conditions before postemergence herbicide application reduced the probability of successful control for several of the herbicide by weed species models. As air temperatures increase and rainfall becomes more variable, weed control with many of the commonly used postemergence herbicides is likely to become less reliable.
The gut microbiome is impacted by certain types of dietary fibre. However, the type, duration and dose needed to elicit gut microbial changes and whether these changes also influence microbial metabolites remain unclear. This study investigated the effects of supplementing healthy participants with two types of non-digestible carbohydrates (resistant starch (RS) and polydextrose (PD)) on the stool microbiota and microbial metabolite concentrations in plasma, stool and urine, as secondary outcomes in the Dietary Intervention Stem Cells and Colorectal Cancer (DISC) Study. The DISC study was a double-blind, randomised controlled trial that supplemented healthy participants with RS and/or PD or placebo for 50 d in a 2 × 2 factorial design. DNA was extracted from stool samples collected pre- and post-intervention, and V4 16S rRNA gene sequencing was used to profile the gut microbiota. Metabolite concentrations were measured in stool, plasma and urine by high-performance liquid chromatography. A total of fifty-eight participants with paired samples available were included. After 50 d, no effects of RS or PD were detected on composition of the gut microbiota diversity (alpha- and beta-diversity), on genus relative abundance or on metabolite concentrations. However, Drichlet’s multinomial mixture clustering-based approach suggests that some participants changed microbial enterotype post-intervention. The gut microbiota and fecal, plasma and urinary microbial metabolites were stable in response to a 50-d fibre intervention in middle-aged adults. Larger and longer studies, including those which explore the effects of specific fibre sub-types, may be required to determine the relationships between fibre intake, the gut microbiome and host health.
Members of the genus Scaphanocephalus mature in accipitrids, particularly osprey, Pandion haliaetus, with metacercaria causing Black Spot Syndrome in reef fishes. In most of the world, only the type species, Scaphanocephalus expansus (Creplin, 1842) has been reported. Recent molecular studies in the Western Atlantic, Mediterranean and Persian Gulf reveal multiple species of Scaphanocephalus, but have relied on 28S rDNA, mainly from metacercariae, which limits both morphological identification and resolution of closely related species. Here we combine nuclear rDNA with mitochondrial sequences from adult worms collected in osprey across North America and the Caribbean to describe species and elucidate life cycles in Scaphanocephalus. A new species described herein can be distinguished from S. expansus based on overall body shape and size. Phylogenetic analysis of the whole mitochondrial genome of Scaphanocephalus indicates a close relationship with Cryptocotyle. We conclude that at least 3 species of Scaphanocephalus are present in the Americas and 2 others are in the Old World. Specimens in the Americas have similar or identical 28S to those in the Mediterranean and Persian Gulf, but amphi-Atlantic species are unlikely in light of divergence in cytochrome c oxidase I and the lack of amphi-Atlantic avian and fish hosts. Our results provide insight into the geographic distribution and taxonomy of a little-studied trematode recently linked to an emerging pathology in ecologically important reef fishes.
Zeolites and other open framework materials provide a powerful tool for remediation and solidification of a range of cationic wastes (e.g.${\rm{NH}}_4^ + $, Pb2+) due to the combined properties of large surface area and cation exchange capacity. However, practical barriers exist to the continued expansion of their use, including handling issues related to the fine particle size, and continued ion exchange following waste adsorption. This study examines the synthesis and characterization of zeolites adhered to a muscovite mica wafer, in order to assess if practical benefit can be derived from the preparation of layered composite materials. The paper demonstrates that increased metal adsorption, as demonstrated by surface chemical composition, can be induced in regions by growth of zeolite on and within the lamellar structure of the matrix. X-ray diffraction studies suggest that a site-specific crystallization mechanism controls the zeolite type and extent of growth, thereby reducing control over the zeolites prepared. However, although increased adsorption has been introduced to the mica, the amount of zeolite added is small (<50 mg per gram of muscovite), and thus any adsorption is very limited.
Developed in 2014, the Systematic Review (SR) Toolbox has played a critical role in helping researchers to identify appropriate tools to support systematic reviews. Since the resource was launched, the systematic review and wider evidence synthesis process has evolved considerably. The way in which the SR Toolbox originally classified tools at launch had become dated. We updated and rebuilt the SR Toolbox in 2022 underpinned by a novel taxonomy to reflect the latest review and evidence synthesis landscape.
Methods
All guidance and software tools contained within the SR Toolbox were manually extracted in February 2022. Information contained from tool records were extracted by a single reviewer into an Excel spreadsheet, with a second reviewer checking a sample. The spreadsheet was translated to a Microsoft Access database underpinned with a new taxonomy to reflect the expansion of evidence synthesis methods and new review types (or ‘families’). A brief analysis of the remapped tools was conducted to identify current gaps in software and guidance support for evidence synthesis. A new user interface was also developed.
Results
The updated version of the SR Toolbox was launched 13 May 2022. At that time, the resource included records on 235 software tools and 112 guidance tools. Regarding ‘review families’, most software tools (n = 223) and guidance documents (n = 78) were applicable to supporting systematic reviews. Fewer software (n = 66) and guidance (n = 22) tools were applicable to reviews of reviews, while qualitative reviews were less served by guidance documents (n = 19). In terms of ‘review stages’, most guidance documents were associated with quality assessment (n = 70), while most software was related to searching (n = 84) and synthesis (n = 82). To-date, there is a lack of software (n = 2) and guidance (n = 3) tools to support stakeholder engagement.
Conclusions
The SR Toolbox has received a significant update to ensure that tools are classified and shared based on the latest systematic review and evidence synthesis methods. As part of the update, analysis of the contents of the toolbox highlighted potential gaps in tool support for certain review types/stages.
OBJECTIVES/GOALS: Glioblastomas (GBMs) are heterogeneous, treatment-resistant tumors that are driven by populations of cancer stem cells (CSCs). In this study, we perform an epigenetic-focused functional genomics screen in GBM organoids and identify WDR5 as an essential epigenetic regulator in the SOX2-enriched, therapy resistant cancer stem cell niche. METHODS/STUDY POPULATION: Despite their importance for tumor growth, few molecular mechanisms critical for CSC population maintenance have been exploited for therapeutic development. We developed a spatially resolved loss-of-function screen in GBM patient-derived organoids to identify essential epigenetic regulators in the SOX2-enriched, therapy resistant niche. Our niche-specific screens identified WDR5, an H3K4 histone methyltransferase responsible for activating specific gene expression, as indispensable for GBM CSC growth and survival. RESULTS/ANTICIPATED RESULTS: In GBM CSC models, WDR5 inhibitors blocked WRAD complex assembly and reduced H3K4 trimethylation and expression of genes involved in CSC-relevant oncogenic pathways. H3K4me3 peaks lost with WDR5 inhibitor treatment occurred disproportionally on POU transcription factor motifs, required for stem cell maintenance and including the POU5F1(OCT4)::SOX2 motif. We incorporated a SOX2/OCT4 motif driven GFP reporter system into our CSC cell models and found that WDR5 inhibitor treatment resulted in dose-dependent silencing of stem cell reporter activity. Further, WDR5 inhibitor treatment altered the stem cell state, disrupting CSC in vitro growth and self-renewal as well as in vivo tumor growth. DISCUSSION/SIGNIFICANCE: Our results unveiled the role of WDR5 in maintaining the CSC state in GBM and provide a rationale for therapeutic development of WDR5 inhibitors for GBM and other advanced cancers. This conceptual and experimental framework can be applied to many cancers, and can unmask unique microenvironmental biology and rationally designed combination therapies.
Hydrodynamic clogging in planar channels is studied via direct numerical simulation for the first time, utilising a novel numerical test cell and stochastic methodology with special focus on the influence of electrostatic forces. Electrostatic physics is incorporated into an existing coupled lattice Boltzmann-discrete element method framework, which is verified rigorously. First, the dynamics of the problem is governed by the Stokes number, $St$. At low $St$, the clogging probability, $P$, increases with $St$ due to increasing collision frequency. At high $St$, however, $P$ decreases with $St$ due to quadratic scaling of hydrodynamic force acting on arches. Under electrostatic forces, clogging is well represented by the wall adhesion number, $Ad_w$. For $Ad_w \lesssim 4$, the mechanical dependence on $St$ is exhibited, while for $4 < Ad_w < 20$, there is a transition to high $P$ as sliding along, and attachment to, the channel surface occurs increasingly. For $Ad_w \gtrsim 20$, clogging occurs with $P > 0.95$. Particle agglomeration, however, can also decrease $P$ due to diminished interaction with channel walls. Distinct parametric regions of clogging are also observed in relation to the channel width, while a critical width $w/d^*=2.6$ is reported, which increases to $w/d^*=4$ with strong electrostatic surface attachment. The number of particles that form stable arches across a planar channel is determined to be $n=\left \lceil {w/d}\right \rceil + 1$. Finally, sensitivity to the Coulomb friction coefficient is determined in favour of calibrating numerical parameters to bulk system behaviour. The greatest sensitivities occur in situations where the arch stability is lowest, while clogging becomes independent of friction for strong wall adhesion.
Among patients with a history of ESBL infection, uncertainty remains regarding whether all of these patients require ESBL-targeted therapy when presenting with a subsequent infection. We sought to determine the risks associated with a subsequent ESBL infection to help inform empiric antibiotic decisions.
Methods:
A retrospective cohort study of adult patients with positive index culture for Escherichia coli or Klebsiella pneumoniae (EC/KP) receiving medical care during 2017 was conducted. Risk assessments were performed to identify factors associated with subsequent infection caused by ESBL-producing EC/KP.
Results:
In total, 200 patients were included in the cohort, 100 with ESBL-producing EC/KP and 100 with ESBL-negative EC/KP. Of 100 patients (50%) who developed a subsequent infection, 22 infections were ESBL-producing EC/KP, 43 were other bacteria, and 35 had no or negative cultures. Subsequent infection caused by ESBL-producing EC/KP only occurred when the index culture was also ESBL-producing (22 vs 0). Among those with ESBL-producing index culture, the incidences of subsequent infection caused by ESBL-producing EC/KP versus other bacterial subsequent infection were similar (22 vs 18; P = .428). Factors associated with subsequent infection caused by ESBL-producing EC/KP include history of ESBL-producing index culture, time ≤180 days between index culture and subsequent infection, male sex, and Charlson comorbidity index score >3.
Conclusions:
History of ESBL-producing EC/KP culture is associated with subsequent infection caused by ESBL-producing EC/KP, particularly within 180 days after the historical culture. Among patients presenting with infection and a history of ESBL-producing EC/KP, other factors should be considered in making empiric antibiotic decisions, and ESBL-targeted therapy may not always be warranted.
Many clinical trials leverage real-world data. Typically, these data are manually abstracted from electronic health records (EHRs) and entered into electronic case report forms (CRFs), a time and labor-intensive process that is also error-prone and may miss information. Automated transfer of data from EHRs to eCRFs has the potential to reduce data abstraction and entry burden as well as improve data quality and safety.
Methods:
We conducted a test of automated EHR-to-CRF data transfer for 40 participants in a clinical trial of hospitalized COVID-19 patients. We determined which coordinator-entered data could be automated from the EHR (coverage), and the frequency with which the values from the automated EHR feed and values entered by study personnel for the actual study matched exactly (concordance).
Results:
The automated EHR feed populated 10,081/11,952 (84%) coordinator-completed values. For fields where both the automation and study personnel provided data, the values matched exactly 89% of the time. Highest concordance was for daily lab results (94%), which also required the most personnel resources (30 minutes per participant). In a detailed analysis of 196 instances where personnel and automation entered values differed, both a study coordinator and a data analyst agreed that 152 (78%) instances were a result of data entry error.
Conclusions:
An automated EHR feed has the potential to significantly decrease study personnel effort while improving the accuracy of CRF data.
With advances in care, an increasing number of individuals with single-ventricle CHD are surviving into adulthood. Partners of individuals with chronic illness have unique experiences and challenges. The goal of this pilot qualitative research study was to explore the lived experiences of partners of individuals with single-ventricle CHD.
Methods:
Partners of patients ≥18 years with single-ventricle CHD were recruited and participated in Experience Group sessions and 1:1 interviews. Experience Group sessions are lightly moderated groups that bring together individuals with similar circumstances to discuss their lived experiences, centreing them as the experts. Formal inductive qualitative coding was performed to identify salient themes.
Results:
Six partners of patients participated. Of these, four were males and four were married; all were partners of someone of the opposite sex. Themes identified included uncertainty about their partners’ future health and mortality, becoming a lay CHD specialist, balancing multiple roles, and providing positivity and optimism. Over time, they took on a role as advocates for their partners and as repositories of medical history to help navigate the health system. Despite the uncertainties, participants described championing positivity and optimism for the future.
Conclusions:
In this first-of-its-kind pilot study, partners of individuals with single-ventricle CHD expressed unique challenges and experiences in their lives. There is a tacit need to design strategies to help partners cope with those challenges. Further larger-scale research is required to better understand the experiences of this unique population.
‘A spectre is haunting Europe – the spectre of Communism.’1 Introducing the Communist Manifesto, Karl Marx and Friedrich Engels cast communism as an ill-defined force that allowed ‘all the Powers in Europe’ to tar all political opposition with its stigma. It was therefore ‘high time … to meet this nursery tale of the Spectre of Communism with a Manifesto of the party itself.’ But communism was already much more than that.
Despite increasing evidence for the effectiveness of individual psychological interventions for bipolar disorder, research on older adults is lacking. We report the first randomised controlled trial of psychological therapy designed specifically for older adults with bipolar disorder.
Aims
To evaluate the feasibility and acceptability of recovery-focused therapy, designed in collaboration with older people living with bipolar disorder.
Method
A parallel, two-armed, randomised controlled trial comparing treatment as usual with up to 14 sessions of recovery-focused therapy plus treatment as usual, for older adults with bipolar disorder.
Results
Thirty-nine participants (67% female, mean age 67 years) were recruited over a 17-month period. Feasibility and acceptability of recruitment, retention (>80% observer-rated outcomes at both 24 and 48 weeks) and intervention processes were demonstrated. The majority of participants started therapy when offered, adhered to the intervention (68% attended all sessions and 89% attended six or more sessions) and reported positive benefits. Clinical assessment measures provide evidence of a signal for effectiveness on a range of outcomes including mood symptoms, time to relapse and functioning. No trial-related serious adverse events were identified.
Conclusions
Recovery-focused therapy is feasible, acceptable and has the potential to improve a range of outcomes for people living with bipolar disorder in later life. A large-scale trial is warranted to provide a reliable estimate of its clinical and cost-effectiveness.
Recently, defaults have become celebrated as a low-cost and easy-to-implement nudge for promoting positive outcomes, both at an individual and societal level. In the present research, we conducted a large-scale field experiment (N = 32,508) in an educational context to test the effectiveness of a default intervention in promoting participation in a potentially beneficial achievement test. We found that a default manipulation increased the rate at which high school students registered to take the test but failed to produce a significant change in students’ actual rate of test-taking. These results join past literature documenting robust effects of default framings on initial choice but marked variability in the extent to which those choices ultimately translate to real-world outcomes. We suggest that this variability is attributable to differences in choice-to-outcome pathways – the extent to which the initial choice is causally determinative of the outcome.
To examine differences in surgical practices between salaried and fee-for-service (FFS) surgeons for two common degenerative spine conditions. Surgeons may offer different treatments for similar conditions on the basis of their compensation mechanism.
Methods:
The study assessed the practices of 63 spine surgeons across eight Canadian provinces (39 FFS surgeons and 24 salaried) who performed surgery for two lumbar conditions: stable spinal stenosis and degenerative spondylolisthesis. The study included a multicenter, ambispective review of consecutive spine surgery patients enrolled in the Canadian Spine Outcomes and Research Network registry between October 2012 and July 2018. The primary outcome was the difference in type of procedures performed between the two groups. Secondary study variables included surgical characteristics, baseline patient factors, and patient-reported outcome.
Results:
For stable spinal stenosis (n = 2234), salaried surgeons performed statistically fewer uninstrumented fusion (p < 0.05) than FFS surgeons. For degenerative spondylolisthesis (n = 1292), salaried surgeons performed significantly more instrumentation plus interbody fusions (p < 0.05). There were no statistical differences in patient-reported outcomes between the two groups.
Conclusions:
Surgeon compensation was associated with different approaches to stable lumbar spinal stenosis and degenerative lumbar spondylolisthesis. Salaried surgeons chose a more conservative approach to spinal stenosis and a more aggressive approach to degenerative spondylolisthesis, which highlights that remuneration is likely a minor determinant in the differences in practice of spinal surgery in Canada. Further research is needed to further elucidate which variables, other than patient demographics and financial incentives, influence surgical decision-making.
Background: Carbapenem resistance in gram-negative organisms is an important public health problem. The CDC conducted Sentinel surveillance in 2018–2019 to characterize these organisms from 9 facilities in 9 different states. Methods: Carbapenem-resistant Enterobacterales (CRE), Pseudomonas aeruginosa (CRPA), and Acinetobacter spp (CRA) obtained from clinical samples of patients in acute-care or long-term care facilities were submitted to the CDC. Identification was confirmed using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF), and antimicrobial susceptibility testing (AST) was performed via broth microdilution for 27 antibiotics. All confirmed CRE and CRPA were tested for carbapenemase production (CP) using the modified carbapenem inactivation method (mCIM). The isolates that were mCIM-positive were assessed by real-time PCR for presence of blaKPC, blaNDM, blaVIM, and blaIMP. CP-CRE were also assessed for blaOXA-48-like. All confirmed CRA were tested for the same genes as CRPA and blaOXA-23–like, blaOXA-24/40-like, blaOXA-58–like, and blaOXA-235–like genes. Difficult-to-treat resistance (DTR) was defined as resistance to all β-lactams (excluding newer β-lactam combination agents) and quinolones tested. Results: The CDC confirmed 208 CRE, 161 CRPA, and 94 CRA. Table 1 summarizes AST results for a selection of drugs. We identified 112 (53.8%) mCIM-positive CRE and 6 (3.7%) mCIM-positive CRPA. The PCR results are summarized in Table 2. One mCIM-positive and PCR-negative isolate was positive in a metallo-β-lactamase screen. Conclusions: Resistance among CRE and CRPA to newer β-lactam combination agents was detected. Options for treating CRA are limited. Of 112 CP-CRE, 85.7% harbored blaKPC; CP-CRPA were rare (3.7%); and most CRA harbored blaOXA-23-like (55.3%) or blaOXA-24/40-like (30.9%). Whole-genome sequencing is planned to better understand gene variants, sequence types, and additional resistance markers present among the isolates.
To compare 2 methods of communicating polymerase chain reaction (PCR) blood-culture results: active approach utilizing on-call personnel versus passive approach utilizing notifications in the electronic health record (EHR).
Design:
Retrospective observational study.
Setting:
A tertiary-care academic medical center.
Patients:
Adult patients hospitalized with ≥1 positive blood culture containing a gram-positive organism identified by PCR between October 2014 and January 2018.
Methods:
The standard protocol for reporting PCR results at baseline included a laboratory technician calling the patient’s nurse, who would report the critical result to the medical provider. The active intervention group consisted of an on-call pager system utilizing trained pharmacy residents, whereas the passive intervention group combined standard protocol with real-time in-basket notifications to pharmacists in the EHR.
Results:
Of 209 patients, 105, 61, and 43 patients were in the control, active, and passive groups, respectively. Median time to optimal therapy was shorter in the active group compared to the passive group and control (23.4 hours vs 42.2 hours vs 45.9 hours, respectively; P = .028). De-escalation occurred 12 hours sooner in the active group. In the contaminant group, empiric antibiotics were discontinued faster in the active group (0 hours) than in the control group and the passive group (17.7 vs 7.2 hours; P = .007). Time to active therapy and days of therapy were similar.
Conclusions:
A passive, electronic method of reporting PCR results to pharmacists was not as effective in optimizing stewardship metrics as an active, real-time method utilizing pharmacy residents. Further studies are needed to determine the optimal method of communicating time-sensitive information.
OBJECTIVES/GOALS: Perioperative surgical care is team-based with close partnership between surgeons, residents, advanced practice professionals (APPs), and others. The objective is to develop an understanding of the current state and implementation needs required for APPs to engage surgical patients in advanced care planning (ACP) to promote goal concordant care. METHODS/STUDY POPULATION: We will conduct a mixed methods evaluation of ACP knowledge, attitudes, and beliefs amongst surgical APPs to identify barriers and facilitators of APPs engaging in a team-based approach to engaging surgical patients in ACP. We will conduct an online survey and qualitative interviews in the following 4 domains: 1) knowledge, skills, and attitudes about engaging in ACP with a patient or their surrogate decision maker during their perioperative care; 2) prior ACP-specific education; 3) experiences conducting ACP discussions with patients; and 4) perceived training needs to increase ACP uptake and documentation. The findings will provide the foundations to design team-based interventions focused on addressing the barriers and inform training and coaching needs to develop expertise and comfort in the ACP process. RESULTS/ANTICIPATED RESULTS: We expect variability in the knowledge, skills, attitudes, and experiences with the ACP process. We anticipate gaining a better understanding of the educational materials best suited to support APPs as they begin engaging patients in ACP. Possible barriers to APP-led ACP discussions include inconsistent role delineation, uncertainty about the value of pre-operative vs. post-operative ACP discussions, lack of experience engaging in ACP discussion, and lack of familiarity with electronic health records ACP tools. Possible facilitators of APP-led ACP discussions may be related to past work experience settings, exposure to ACP in educational preparation, hands-on observation of value of ACP in surgical patients and influences from attending and residents. DISCUSSION/SIGNIFICANCE: While current ACP research in surgery focuses on physician-led patient engagement in ACP discussions, there is a paucity of research focusing on how to develop a team-based approach to ACP discussions in surgery. This study will provide information necessary for the development of interventions that increase team-based ACP for surgical patients.
The shear-induced migration of dense suspensions with continuously distributed (polydisperse) particle sizes is investigated in planar channel flows for the first time. A coupled lattice Boltzmann–discrete element method numerical framework is employed and validated against benchmark experimental results of bulk shear-induced migration and segregation by particle size. Distinct dependence on the particle size distribution is shown in the flowing (non-plugged) regime (where the bulk solid volume fraction, $\bar{\phi}$, $\leq 0.3$) resulting from a dual dependence on the particle self-diffusivity and local rheology imposed by the particle pressure gradient. Close agreement between statistically equivalent bidisperse and polydisperse suspensions suggests that the bulk migration, and by extension the shear-induced diffusivity, is completely characterised by the first three statistical moments of the particle size distribution. For both bidisperse and polydisperse suspensions in the plugging regime, $\bar {\phi }\geq 0.4$, the smallest particles preferentially form the plugs, causing the largest particles to segregate to the channel walls. This effect is accentuated as $\bar {\phi }$ increases and has not been reported in the literature hitherto. It is proposed that smaller particles preferentially form the plugs due to their higher shear-rate fluctuations, which completely dominate particle motion near the plug where the mean shear rate vanishes. Finally, increasing inertia causes a greater bulk migration towards the channel walls, but increased mid-plane migration for the largest particles due to the dependence of the particle self-diffusivity on the particle Reynolds number. As $\bar {\phi }$ increases shear-induced migration dominates and these inertial effects disappear, as does dependence on the particle size distribution.
Significant upgrades to the Rapid Air Movement (RAM) Drill were developed and tested by the US Ice Drilling Program in 2016 through 2020 for the U.S. National Science Foundation. The design of the system leverages the existing infrastructure of the RAM Drill with the goal of greatly reducing the logistical burden of deploying the drill while maintaining the ability to drill an access hole in firn and ice to 100 m in 40 min or less. In this paper, characteristics of the drill are described, along with a description of the drill performance during the testing at Raven Camp in Greenland and at WAIS Divide Camp in Antarctica.