Revealing the hidden structure of disordered materials by parameterizing their local structural manifold.

Durable interest in developing a framework for the detailed structure of glassy materials has produced numerous structural descriptors that trade off between general applicability and interpretability. However, none approach the combination of simplicity and wide-ranging predictive power of the lattice-grain-defect framework for crystalline materials. Working from the hypothesis that the local atomic environments of a glassy material are constrained by enthalpy minimization to a low-dimensional manifold in atomic coordinate space, we develop a generalized distance function, the Gaussian Integral Inner Product (GIIP) distance, in connection with agglomerative clustering and diffusion maps, to parameterize that manifold. Applying this approach to a two-dimensional model crystal and a three-dimensional binary model metallic glass results in parameters interpretable as coordination number, composition, volumetric strain, and local symmetry. In particular, we show that a more slowly quenched glass has a higher degree of local tetrahedral symmetry at the expense of cyclic symmetry. While these descriptors require post-hoc interpretation, they minimize bias rooted in crystalline materials science and illuminate a range of structural trends that might otherwise be missed.

Simulation for diversity, equity and inclusion in emergency medicine residency training: A qualitative study.

Background: The last few years have seen an increased focus on diversity, equity, and inclusion (DEI) initiatives across organizations. Simulation has been used in varying degrees for teaching about DEI topics with emergency medicine; however, there are no established best practices or guidelines on this subject. To further examine the use of simulation for DEI teachings, the DEISIM work group was created as a collaboration between the Society of Academic Emergency Medicine (SAEM) Simulation Academy and the Academy for Diversity and Inclusion in Emergency Medicine (ADIEM). This study represents their findings. Method: This qualitative study was conducted using a three-pronged approach. Initial literature search was conducted followed by a call for submission of simulation curricula. These were then followed by five focus groups. Focus groups were recorded, transcribed by a professional transcription service, and then subjected to thematic analysis. Results: Data were analyzed and organized into four broad categories including Learners, Facilitators, Organizational/Leadership, and Technical Issues. Challenges within each of these were identified, as were potential solutions. Select pertinent findings included focused faculty development, a carefully planned approach that utilized DEI content experts and the use of simulation for workplace microaggressions or discriminations. Conclusions: There appears to be a clear role for simulation in DEI teachings. Such curricula, however, should be undertaken with careful planning and input from appropriate and representative parties. More research is needed on optimizing and standardizing simulation-based DEI curricula.

Toxicological assessment of dihydroberberine.

A battery of studies was conducted to examine the toxicological potential of dihydroberberine (DHBBR), a derivative of berberine (BBR). The genotoxicity studies conducted on DHBBR, including the bacterial reverse mutation test, the mouse lymphoma assay, and the in vivo micronucleus test, showed that DHBBR is non-mutagenic and non-clastogenic. An acute oral toxicity study revealed that the LD50 of DHBBR in female Sprague Dawley rats was greater than 2000 mg/kg bw. In a 14-day oral dose range finding study, the maximum tolerated dose was the high dose, 120 mg/kg bw/day. Based on a 90-day oral toxicity study in male and female Sprague Dawley rats, it was concluded that the NOAEL for DHBBR is 100 mg/kg bw/day, the highest dose tested.

Identifying pediatric patients with multisystem inflammatory syndrome in children presenting to a pediatric emergency department.

OBJECTIVE: To compare clinical and laboratory features of children with Multisystem Inflammatory Syndrome in Children (MIS-C) to those evaluated for MIS-C in the Emergency Department (ED). METHODS: We conducted a retrospective review of the medical record of encounters with testing for inflammatory markers in an urban, tertiary care Pediatric ED from March 1, 2020 to July 31, 2020. We abstracted demographic information, laboratory values, selected medications and diagnoses. We reviewed the record for clinical presentation for the subset of patients admitted to the hospital for suspected MIS-C. We then used receiver operating curves and logistic regression to evaluate the utility of candidate laboratory values to predict MIS-C status. RESULTS: We identified 32 patients with confirmed MIS-C and 15 admitted and evaluated for MIS-C but without confirmation of SARS CoV-2 infection. We compared these patients to 267 encounters with screening laboratories for MIS-C. Confirmed MIS-C patients had an older median age, higher median fever on presentation and were predominantly of Hispanic and non-Hispanic Black race/ethnicity. All children with MIS-C had a C-reactive protein (CRP) >4.5 mg/dL, were more likely to have Brain Natriuretic Peptide >400 pg/mL (OR 10.50, 95%CI 4.40-25.04), D-Dimer >3 µg/mL (7.51, [3.18-17.73]), and absolute lymphocyte count (ALC) <1.5 K/mcL (21.42, [7.19-63.76]). We found CRP >4.5 mg/dL and ALC <1.5 K/mcL to be 86% sensitive and 91% specific to identify MIS-C among patients screened in our population. CONCLUSIONS: We identified that elevated CRP and lymphopenia was 86% sensitive and 91% specific for identification of children with MIS-C.

Creation of a standardized pediatric emergency medicine simulation curriculum for emergency medicine residents.

BACKGROUND: The majority of children seeking care in emergency departments are seen by general emergency medicine (EM) residency program graduates. Throughout training, EM residents manage fewer critically ill pediatric patients compared to adults, and the exposure to children with illness and injury requiring emergent assessment and management is often limited and sporadic across training sites. This report describes the creation of a robust set of simulation cases for EM trainees incorporating topics identified during a previous modified Delphi study to improve their pediatric acute care knowledge and skills. METHODS: All 30 pediatric EM topics and 19/26 procedures previously identified as "must be taught by simulation" to EM residents were mapped to 15 simulation case topics. Twenty-seven authors from 16 institutions created cases and supporting materials. Each case was iteratively implemented during a peer review process at two to five sites with EM residents. Feedback from learners and facilitators was collected via electronic surveys and used to revise each case before the next implementation. RESULTS: Thirty-five institutions participated in the peer review process. Fifty-one facilitators and 281 participants (90% EM residents) completed surveys. Most facilitators (98%) agreed or strongly agreed with the statement "This simulation case is relevant to the field of emergency medicine." A majority of facilitators and participants agreed or strongly agreed with the statements "The simulation case was realistic" (98% of facilitators, 94% of participants) and "This simulation case was effective in teaching resuscitation skills" (92% of facilitators, 98% of participants). Most participants reported confidence in knowledge and skills addressed in the learning objectives after participation. CONCLUSIONS: Facilitators and EM residents found cases from a novel simulation-based curriculum covering critical pediatric EM topics relevant, realistic, and effective. This curriculum can help provide a standardized, uniform experience for EM residents who will care for critically ill pediatric patients in their communities.

An assessment of mutagenicity, genotoxicity, acute-, subacute and subchronic oral toxicity of paraxanthine (1,7-dimethylxanthine).

Paraxanthine or 1,7-dimethylxanthine is a natural dietary component and the main metabolite of caffeine in humans. A battery of toxicological studies was conducted in accordance with international guidelines to investigate mutagenicity, genotoxicity and acute and repeated-dose oral toxicity in rats of synthetic paraxanthine (ENFINITY™, Ingenious Ingredients, L.P., >99% purity). There was no evidence of mutagenicity in a bacterial reverse mutation as well as in an in vitro mammalian chromosomal aberration test. There was no evidence of genotoxicity in an in vivo mammalian erythrocyte micronucleus test as well as in an in vitro mammalian cell gene mutation test. An acute oral toxicity test resulted in a LD50 value of 1601 mg/kg bw/d. Paraxanthine did not cause mortality or toxic effects in a subacute 28-day repeated-dose oral toxicity study at daily doses of 75, 150, or 300 mg/kg bw/d (each group n = 10 per sex), administered by gavage. Paraxanthine also did not cause mortality or toxic effects in a subchronic 90-day repeated-dose oral toxicity study at daily doses of 75, 150, or 300 mg/kg bw/d (each group n = 10 per sex), administered by gavage. The no observed adverse effect level (NOAEL) determined from the 90-day study was greater than or equal to 300 mg/kg bw/d, the highest dose tested, for both male and female Wistar rats.

Embodiment in 18th Century Depictions of Human-Machine Co-Creativity.

Artificial intelligence has a rich history in literature; fiction has shaped how we view artificial agents and their capacities in the real world. This paper looks at embodied examples of human-machine co-creation from the literature of the Long 18th Century (1,650-1,850), examining how older depictions of creative machines could inform and inspire modern day research. The works are analyzed from the perspective of design fiction with special focus on the embodiment of the systems and the creativity exhibited by them. We find that the chosen examples highlight the importance of recognizing the environment as a major factor in human-machine co-creative processes and that some of the works seem to precede current examples of artificial systems reaching into our everyday lives. The examples present embodied interaction in a positive, creativity-oriented way, but also highlight ethical risks of human-machine co-creativity. Modern day perceptions of artificial systems and creativity can be limited to some extent by the technologies available; fictitious examples from centuries past allow us to examine such limitations using a Design Fiction approach. We conclude by deriving four guidelines for future research from our fictional examples: 1) explore unlikely embodiments; 2) think of situations, not systems; 3) be aware of the disjunction between action and appearance; and 4) consider the system as a situated moral agent.

Simulation-based emergency medicine education in the era of physical distancing.

Background: The COVID-19 pandemic posed significant challenges to traditional simulation education. Because simulation is considered best practice for competency-based education, emergency medicine (EM) residencies adapted and innovated to accommodate to the new pandemic normal. Our objectives were to identify the impact of the pandemic on EM residency simulation training, to identify unique simulation adaptations and innovations implemented during the pandemic, and to analyze successes and failures through existing educational frameworks to offer guidance on the use of simulation in the COVID-19 era. Methods: The Society for Academic Emergency Medicine (SAEM)'s Simulation Academy formed the SimCOVID task force to examine the impact of COVID-19 on simulation didactics. A mixed-methods approach was employed. A literature search was conducted on the subject and used to develop an exploratory survey that was distributed on the Simulation Academy Listserv. The results were subjected to thematic analysis and examined through existing educational frameworks to better understand successes and failures and then used to generate suggestions on the use of simulation in the COVID-19 era. Results: Thirty programs responded to the survey. Strategies reported included adaptations to virtual teleconferencing and small-group in situ training with a focus on procedural training and COVID-19 preparedness. Successful continuation or relaunching of simulation programs was predicated on several factors including willingness for curricular pivots through rapid iterative prototyping, embracing teleconferencing software, technical know-how, and organizational and human capacity. In specific instances the use of in situ simulation for COVID-19 preparedness established the view of simulation as a "value add" to the organization. Conclusions: Whereas simulation educator's responses to the COVID-19 pandemic can be better appreciated through the lens of iterative curricular prototyping, their successes and failures depended on existing expertise in technological, pedagogical, and content knowledge. That knowledge needed to exist and synergize within a system that had the human and organizational capacity to prioritize and invest in strategies to respond to the rapidly evolving crisis in a proactive manner. Going forward, administrators and educators will need to advocate for continued investment in human and organizational capacity to support simulation-based efforts for the evolving clinical and educational landscape.

A Modified Delphi Study to Prioritize Content for a Simulation-based Pediatric Curriculum for Emergency Medicine Residency Training Programs.

OBJECTIVES: Pediatric training is an essential component of emergency medicine (EM) residency. The heterogeneity of pediatric experiences poses a significant challenge to training programs. A national simulation curriculum can assist in providing a standardized foundation of pediatric training experience to all EM trainees. Previously, a consensus-derived set of content for a pediatric curriculum for EM was published. This study aimed to prioritize that content to establish a pediatric simulation-based curriculum for all EM residency programs. METHODS: Seventy-three participants were recruited to participate in a three-round modified Delphi project from 10 stakeholder organizations. In round 1, participants ranked 275 content items from a published set of pediatric curricular items for EM residents into one of four categories: definitely must, probably should, possibly could, or should not be taught using simulation in all residency programs. Additionally, in round 1 participants were asked to contribute additional items. These items were then added to the survey in round 2. In round 2, participants were provided the ratings of the entire panel and asked to rerank the items. Round 3 involved participants dichotomously rating the items. RESULTS: A total of 73 participants participated and 98% completed all three rounds. Round 1 resulted in 61 items rated as definitely must, 72 as probably should, 56 as possibly could, 17 as should not, and 99 new items were suggested. Round 2 resulted in 52 items rated as definitely must, 91 as probably should, 120 as possibly could, and 42 as should not. Round 3 resulted in 56 items rated as definitely must be taught using simulation in all programs. CONCLUSIONS: The completed modified Delphi process developed a consensus on 56 pediatric items that definitely must be taught using simulation in all EM residency programs (20 resuscitation, nine nonresuscitation, and 26 skills). These data will serve as a targeted needs assessment to inform the development of a standard pediatric simulation curriculum for all EM residency programs.

Applying Educational Theory and Best Practices to Solve Common Challenges of Simulation-based Procedural Training in Emergency Medicine.

OBJECTIVES: Procedural competency is an essential prerequisite for the independent practice of emergency medicine. Multiple studies demonstrate that simulation-based procedural training (SBPT) is an effective method for acquiring and maintaining procedural competency and preferred over traditional paradigms ("see one, do one, teach one"). Although newer paradigms informing SBPT have emerged, educators often face circumstances that challenge and undermine their implementation. The goal of this paper is to identify and report on best practices and theory-supported solutions to some of these challenges as derived using a process of expert consensus building and reviews of the existing literature on SBPT. METHODS: The Society for Academic Emergency Medicine (SAEM) Simulation Academy SBPT Workgroup convened approximately 8 months prior to the 2019 SAEM Annual Meeting to perform a review of the literature and participate in a consensus-building process to identify solutions (in the form of best practices and educational theory) to these challenges faced by educators engaging in SBPT. RESULTS AND ANALYSIS: Thirteen distinct educational challenges to SBPT emerged from the expert group's primary literature reviews and consensus-building processes. Three domains emerged upon further analysis of the 13 challenges: learner, educator, and curriculum. Six challenges within the "learner" domain were selected for comprehensive discussion in this paper, as they were deemed representative of the most common and most significant threats to ideal SBPT. Each of the six challenges aligns with one of the following themes: 1) maximizing active learning, 2) maintaining learner engagement, 3) embracing learner diversity, 4) optimizing cognitive load, 5) promoting mindfulness and reflection, and 6) emphasizing deliberate practice for mastery learning. Over 20 "special treatments" for mitigating the impact of the 13 challenges were derived from the secondary literature search and consensus-building process prior to and during the preconference workshop; 11 of these that best address the six learner-centered challenges are explored, including implications for educators involved in SBPT. CONCLUSIONS/IMPLICATIONS FOR EDUCATORS: We propose multiple consensus-generated solutions (in the form of best practices and applied educational theory) that we believe are suitable and well aligned to overcome commonly encountered learner-centered challenges and threats to optimal SBPT.

Predictors of reflux aspiration and laryngo-pharyngeal reflux.

BACKGROUND: Gastro-esophageal reflux disease (GERD) can present with typical or atypical or laryngo-pharyngeal reflux (LPR) symptoms. Pulmonary aspiration of gastric refluxate is one of the most serious variants of reflux disease as its complications are difficult to diagnose and treat. The aim of this study was to establish predictors of pulmonary aspiration and LPR symptoms. METHODS: Records of 361 consecutive patient from a prospectively populated database were analyzed. Patients were categorized by symptom profile as predominantly LPR or GERD (98 GER and 263 LPR). Presenting symptom profile, pH studies, esophageal manometry and scintigraphy and the relationships were analyzed. RESULTS: Severe esophageal dysmotility was significantly more common in the LPR group (p = 0.037). Severe esophageal dysmotility was strongly associated with isotope aspiration in all patients (p = 0.001). Pulmonary aspiration on scintigraphy was present in 24% of patients. Significant correlation was established between total proximal acid on 24-h pH monitoring and isotope aspiration in both groups (p < 0.01). Rising pharyngeal curves on scintigraphy were the strongest predictors of isotope aspiration (p < 0.01). CONCLUSIONS: Severe esophageal dysmotility correlates with LPR symptoms and reflux aspiration in LPR and GERD. Abnormal proximal acid score on 24-h pH monitoring associated with pulmonary aspiration in reflux patients. Pharyngeal contamination on scintigraphy was the strongest predictor of pulmonary aspiration.

Critical Analysis of an FeP Empirical Potential Employed to Study the Fracture of Metallic Glasses.

An empirical potential that has been widely used to perform molecular dynamics studies on the fracture behavior of FeP metallic glasses is shown to exhibit spinodal decomposition in the composition range commonly studied. The phosphorous segregation induces a transition from ductility to brittleness. During brittle fracture the atomically sharp crack tip propagates along a percolating path with higher P concentration. This embrittlement is observed to occur over a wide range of chemical compositions, and toughness decreases linearly with the degree of compositional segregation over the entire regime studied. Stable glass forming alloys that can be quenched at low quench rates do not, as a rule, exhibit such thermodynamically unstable behavior near to or above their glass transition temperatures. Hence, the microstructures exhibited in these simulations are unlikely to reflect the actual microstructures or fracture behaviors of the glassy alloys they seek to elucidate.

Local yield stress statistics in model amorphous solids.

We develop and extend a method presented by Patinet, Vandembroucq, and Falk [Phys. Rev. Lett. 117, 045501 (2016)PRLTAO0031-900710.1103/PhysRevLett.117.045501] to compute the local yield stresses at the atomic scale in model two-dimensional Lennard-Jones glasses produced via differing quench protocols. This technique allows us to sample the plastic rearrangements in a nonperturbative manner for different loading directions on a well-controlled length scale. Plastic activity upon shearing correlates strongly with the locations of low yield stresses in the quenched states. This correlation is higher in more structurally relaxed systems. The distribution of local yield stresses is also shown to strongly depend on the quench protocol: the more relaxed the glass, the higher the local plastic thresholds. Analysis of the magnitude of local plastic relaxations reveals that stress drops follow exponential distributions, justifying the hypothesis of an average characteristic amplitude often conjectured in mesoscopic or continuum models. The amplitude of the local plastic rearrangements increases on average with the yield stress, regardless of the system preparation. The local yield stress varies with the shear orientation tested and strongly correlates with the plastic rearrangement locations when the system is sheared correspondingly. It is thus argued that plastic rearrangements are the consequence of shear transformation zones encoded in the glass structure that possess weak slip planes along different orientations. Finally, we justify the length scale employed in this work and extract the yield threshold statistics as a function of the size of the probing zones. This method makes it possible to derive physically grounded models of plasticity for amorphous materials by directly revealing the relevant details of the shear transformation zones that mediate this process.

Genetic variation in aspen phytochemical patterns structures windows of opportunity for gypsy moth larvae.

Empirical studies indicate that host-tree bud break will likely advance faster than spring-folivore egg hatch in response to predicted increases in temperature. How these phenological shifts will affect herbivory will depend on temporal patterns of foliar traits that occur during leaf expansion, and their effects on folivore performance. Through fine-scale time series sampling of newly flushed trembling aspen (Populus tremuloides) foliage, we observed a previously unknown peak in phenolic glycoside concentrations that coincides with the emergence of sensitive neonates of gypsy moths and rapidly declines soon after bud break. The magnitude and duration of the initial post-bud break peak in phenolic glycosides varied substantially among genotypes. In contrast, foliar nitrogen concentrations declined at a more uniform rate among genotypes throughout leaf expansion. In addition, leaf toughness remained uniformly low throughout these periods of phytochemical change, and did not rise or vary substantially among genotypes until after anticipated windows of climate change-induced shifts between bud break and egg hatch had elapsed. Controlled manipulation of intervals between gypsy moth egg hatch and aspen bud break generated differences in larval performance among hatch cohorts and host genotypes that corresponded with changes in foliar phenolic glycoside and nitrogen concentrations. These findings indicate that the effects of climate change-induced phenological shifts on herbivory will differ among host plant genotypes, and that genetic variation in foliar chemical patterns will strongly influence this heterogeneity.

Predicting Shear Transformation Events in Metallic Glasses.

Shear transformation is the elementary process for plastic deformation of metallic glasses, the prediction of the occurrence of the shear transformation events is therefore of vital importance to understand the mechanical behavior of metallic glasses. In this Letter, from the view of the potential energy landscape, we find that the protocol-dependent behavior of shear transformation is governed by the stress gradient along its minimum energy path and we propose a framework as well as an atomistic approach to predict the triggering strains, locations, and structural transformations of the shear transformation events under different shear protocols in metallic glasses. Verification with a model Cu_{64}Zr_{36} metallic glass reveals that the prediction agrees well with athermal quasistatic shear simulations. The proposed framework is believed to provide an important tool for developing a quantitative understanding of the deformation processes that control mechanical behavior of metallic glasses.

Tribochemical Wear of Diamond-Like Carbon-Coated Atomic Force Microscope Tips.

Nanoscale wear is a critical issue that limits the performance of tip-based nanomanufacturing and nanometrology processes based on atomic force microscopy (AFM). Yet, a full scientific understanding of nanoscale wear processes remains in its infancy. It is therefore important to quantitatively understand the wear behavior of AFM tips. Tip wear is complex to understand due to adhesive forces and contact stresses that change substantially as the contact geometry evolves due to wear. Here, we present systematic characterization of the wear of commercial Si AFM tips coated with thin diamond-like carbon (DLC) coatings. Wear of DLC was measured as a function of external loading and sliding distance. Transmission electron microscopy imaging, AFM-based adhesion measurements, and tip geometry estimation via inverse imaging were used to assess nanoscale wear and the contact conditions over the course of the wear tests. Gradual wear of DLC with sliding was observed in the experiments, and the tips evolved from initial paraboloidal shapes to flattened geometries. The wear rate is observed to increase with the average contact stress, but does not follow the classical wear law of Archard. A wear model based on the transition state theory, which gives an Arrhenius relationship between wear rate and normal stress, fits the experimental data well for low mean contact stresses (<0.3 GPa), yet it fails to describe the wear at higher stresses. The wear behavior over the full range of stresses is well described by a recently proposed multibond wear model that exhibits a change from Archard-like behavior at high stresses to a transition state theory description at lower stresses.

Multibond Model of Single-Asperity Tribochemical Wear at the Nanoscale.

Single-asperity wear experiments and simulations have identified different regimes of wear including Eyring- and Archard-like behaviors. A multibond dynamics model has been developed based on the friction model of Filippov et al. [Phys. Rev. Lett. 92, 135503 (2004)]. This new model captures both qualitatively distinct regimes of single-asperity wear under a unified theoretical framework. In this model, the interfacial bond formation, wearless rupture, and transfer of atoms are governed by three competing thermally activated processes. The Eyring regime holds under the conditions of low load and low adhesive forces; few bonds form between the asperity and the surface, and wear is a rare and rate-dependent event. As the normal stress increases, the Eyring behavior of wear rate breaks down. A nearly rate-independent regime arises under high load or high adhesive forces, in which wear becomes very nearly, but not precisely, proportional to sliding distance. In this restricted regime, the dependence of wear rate per unit contact area is nearly independent of the normal stress at the point of contact. In true contact between rough elastic surfaces, where contact area is expected to grow linearly with normal load, this would lead to behavior very similar to that described by the Archard equation. Detailed comparisons to experimental and molecular dynamics simulation investigations illustrate both Eyring and Archard regimes, and an intermediate crossover regime between the two.

Coarse graining atomistic simulations of plastically deforming amorphous solids.

The primary mode of failure in disordered solids results from the formation and persistence of highly localized regions of large plastic strains known as shear bands. Continuum-level field theories capable of predicting this mechanical response rely upon an accurate representation of the initial and evolving states of the amorphous structure. We perform molecular dynamics simulations of a metallic glass and propose a methodology for coarse graining discrete, atomistic quantities, such as the potential energies of the elemental constituents. A strain criterion is established and used to distinguish the coarse-grained degrees-of-freedom inside the emerging shear band from those of the surrounding material. A signal-to-noise ratio provides a means of evaluating the strength of the signal of the shear band as a function of the coarse graining. Finally, we investigate the effect of different coarse graining length scales by comparing a two-dimensional, numerical implementation of the effective-temperature description in the shear transformation zone (STZ) theory with direct molecular dynamics simulations. These comparisons indicate the coarse graining length scale has a lower bound, above which there is a high level of agreement between the atomistics and the STZ theory, and below which the concept of effective temperature breaks down.

Developmental and reproductive toxicological evaluation of arachidonic acid (ARA)-Rich oil and docosahexaenoic acid (DHA)-Rich oil.

The purpose of this study was to investigate the reproductive and developmental toxicity of dietary exposure to DHA-rich oil from Schizochytrium sp. and ARA-rich oil from Mortierella alpina. In a developmental toxicity study, pregnant Wistar rats were untreated (control) or administered corn oil (vehicle control), 1000, 2500, or 5000 mg/kg bw/day of DHA-rich oil or ARA-rich oil via gavage from gestation days 6 through 20. In the reproductive toxicity study, male and female Wistar rats were administered vehicle control (corn oil), or 1000, 2500, or 5000 mg/kg bw/day of DHA- or ARA-rich oil via gavage throughout the mating period, pregnancy, and the nursing and lactation period. Differences in the number of fetuses, fetal skeletal malformations, and external and visceral anomalies in the developmental study and mortality, clinical signs, fertility indices, physical observations, gross necropsy findings, and gestation period length in the reproductive toxicity study were not dose-related or significantly different from control groups, and were not considered to be treatment related. The no observed adverse effect level (NOAEL) for maternal toxicity and embryo/fetal development and for paternal or maternal treatment-related reproductive toxicity for the DHA-rich oil and ARA-rich oil administered by gavage, was 5000 mg/kg bw/day.

Connecting Local Yield Stresses with Plastic Activity in Amorphous Solids.

In model amorphous solids produced via differing quench protocols, a strong correlation is established between local yield stress measured by direct local probing of shear stress thresholds and the plastic rearrangements observed during remote loading in shear. This purely local measure shows a higher predictive power for identifying sites of plastic activity when compared with more conventional structural properties. Most importantly, the sites of low local yield stress, thus defined, are shown to be persistent, remaining predictive of deformation events even after fifty or more such plastic rearrangements. This direct and nonperturbative approach gives access to relevant transition pathways that control the stability of amorphous solids. Our results reinforce the relevance of modeling plasticity in amorphous solids based on a gradually evolving population of discrete and local zones preexisting in the structure.