Tip Line Research Articles

Influences of Pre-Existing Fissure Angles and Bridge Angles on Concrete Tensile Failure Characteristics: Insights from Meshless Numerical Simulations.

The existence of cracks is a key factor affecting the strength of concrete. However, traditional numerical methods still have some limitations in the simulation of crack growth in fissured concrete structures. Based on this background, the numerical treatment method of particle failure in smoothed particle hydrodynamics (SPH) is proposed, and the generation method for concrete meso-structures under the smoothed particle hydrodynamics (SPH) framework is developed. The concrete meso-models under different pre-existing micro-fissure inclinations and bridge angles (the inner tip line of the double pre-existing micro-fissure is defined as a bridge, and the angle between the bridge and the horizontal direction is defined as the bridge angle) were established, and numerical simulations of the crack propagation processes of concrete structures under tensile stress were carried out. The main findings were as follows: The concrete meso-structures and the pre-existing micro-fissures all have great impacts on the final failure modes of concrete. The stress-strain curve of the concrete model presents four typical stages. Finally, the crack initiation and propagation mechanisms of fissured concrete are discussed, and the application of smoothed particle hydrodynamics (SPH) in crack simulations of fissured concrete is prospected.

Retinal displacement after surgery for idiopathic macular hole.

To review and summarize the mechanism hypothesis, influencing factors and possible consequences of macular retinal displacement after idiopathic macular hole (IMH) surgery. PubMed and Web of Science database was searched for studies published before April 2023 on "Retinal displacement", "Idiopathic macular holes", and "Macular displacement". Recently, more academics have begun to focus on retinal displacement following idiopathic macular holes. They found that internal limiting membrane (ILM) peeling was the main cause of inducing postoperative position shift in the macular region. Moreover, several studies have revealed that the macular hole itself, as well as ILM peeling method, will have an impact on the result. In addition, this phenomenon is related to postoperative changes in macular retinal thickness, cone outer segment tips line recovery, the occurrence of dissociated optic nerve fiber layer (DONFL) and the degree of metamorphopsia. As a subclinical phenomenon, the clinical significance of postoperative macular displacement cannot be underestimated as it may affect the recovery of anatomy and function.

The role of optical coherence tomography biomarkers in predicting the outcome of epiretinal membrane removal surgery

Epiretinal membrane (ERM) is a common condition that can cause visual impairment. ERM removal surgery is an effective treatment option, but predicting postoperative visual outcomes is challenging. Imaging modalities, particularly optical coherence tomography (OCT), have emerged as valuable tools for preoperative evaluation and predicting surgical outcomes. This presentation focuses on the role of preoperative OCT biomarkers in estimating postoperative vision improvement after ERM removal surgery. Such biomarkers include the disorganization of retinal inner layers (DRIL), the presence of ectopic inner foveal layer (EIFL), the cotton ball sign, the cone outer segment tips (COST) line, the photoreceptor outer segment (PROS) length, the inner retina irregularity index, and the presence of posterior vitreous detachment (PVD).DRIL refers to the abnormal appearance of the inner retinal layers on OCT, and has been found to be associated with poorer postoperative visual outcomes in ERM removal surgery. Significant EIFL has also been associated with poorer visual outcomes after surgery. The cotton ball sign, which appears as a hyper‐reflective area in the inner nuclear layer, has been found to be associated with increased difficulty in ERM removal and poorer visual outcomes. These biomarkers suggest that a greater degree of retinal disorganization and irregularity may lead to more challenging surgeries and poorer visual outcomes.In contrast, the presence of intact COST line and normal PROS length have been associated with better visual function. PVD, which represents separation of the vitreous from the retina, has been shown to be associated with less surgical trauma and better postoperative outcomes. The inner retina irregularity index, which measures the extent of disorganization of the inner retinal layers, has also been found to correlate with the changes in metamorphopsia and quality of vision after surgery.These biomarkers have the potential to improve the accuracy of preoperative evaluation and prediction of surgical outcomes in ERM removal surgery. By identifying patients with a greater degree of retinal disorganization and irregularity, we can anticipate more challenging surgeries and poorer visual outcomes. Conversely, patients with minimal COST line defects, normal PROS length and full PVD may have better postoperative visual outcomes.In summary, preoperative OCT findings can help predict postoperative visual outcomes in ERM removal surgery. The use of imaging modalities and specific biomarkers can provide useful insight in management decisions, case selection, and timing of surgery.

Implementation of SafeVoice Nevada: A Statewide Anonymous Tip Line for School-Age Youth

ABSTRACT The State of Nevada launched the SafeVoice anonymous tip line to prevent harmful events in schools and to promote student safety, health, and wellbeing. SafeVoice is a joint effort of the Nevada Department of Education and Nevada Department of Public Safety. Since its inception in 2017, more than 27,000 tips have been submitted across the state. This article, which presents one of the first detailed studies of a statewide tip line for schools, focuses on the implementation of SafeVoice during its first five years of operation. We present quantitative data about the program (e.g. tip volume and characteristics) from the program database and school staff experiences from an annual survey, as well as qualitative data from documents and interviews with school staff, students, and parents.

Critical Professional Development: A Necessary Risk?

Amy Yarborough, a veteran teacher and curriculum resource leader in a rural district in Virginia, facilitates a professional learning community focused on social justice and equity-oriented instructional practices. When allegations of teaching critical race theory are reported via the state’s email tip line and community social media groups, Amy is asked to present her professional learning community materials to the local school board. In the midst of stakeholder protests and media scrutiny, Amy must decide how to explain her professional decisions. Current and future educational leaders interested in issues related to race and equity will consider the roles of policy and the public in influencing teachers’ lessons.

Commentary: Indistinct retinal outer layers in the walls of idiopathic full thickness macular hole - A potential predictive biomarker for surgical outcomes.

Commentary: Indistinct retinal outer layers in the walls of idiopathic full thickness macular hole - A potential predictive biomarker for surgical outcomes.

Mechanism of Fault Terminations: Theory and Field Examples

ABSTRACT Contrary to the mechanism of initiation and growth of a fault that has been extensively addressed, the termination of the fault is poorly understood. It is generally believed that the major factors such as the zone of weakness, frictional homogeneity, rock tension, and the minor factors such as stress and gravity are responsible for the initiation and growth of faults, while the deficiency of these factors leads to the termination of a fault. A theory of fault-termination has been proposed by combining progressive deformation and branching (as observed on seismic data from the North Sea and Scotian basin) along with the hindrance, flanking, block rotation, enhanced mineralization, relaxation and cohesive strength. This model of progressive deformation during faulting is categorized into three zones: displacement zone in the beginning, displacement shear transition zone in the middle and the shear zone towards the termination. These well-patterned changes of progressive deformation include continuation of shearing beyond the tip line and converting brittle displacement deformation state into shearing displacement towards the termination. This mechanism also elucidates the deformation state for blind thrust, brittle-ductile transition zone within the crust, initiation of the reverse fault and deformation-stress relationship for faulting.

Future Home of the Living God

Future Home of the Living God Michelle Johnson, Managing & Culture Editor Louise Erdrich Future Home of the Living God HarperCollins The first thing that happens at the end of the world is that we don't know what is happening. I LIVE IN Oklahoma, one of the reddest states in these United States. When an antiabortion activist scaled the fifty-story Devon skyscraper in downtown Oklahoma City, I wondered less why someone would take such an outlandish risk and more why someone would think to come to this state, of all states, to make his statement. It was June 14, 2022, and we were already living post-Roe, in a state that had weeks earlier earned the NPR headline "Oklahoma Governor Signs the Strictest Abortion Ban." In August, while browsing secondhand books, I picked up Louise Erdrich's Future Home of the Living God (2017), a novel I had skipped, despite my love of her work. The reviews five years ago were mixed, but I wondered what it would be like to read this story of the capture and confinement of pregnant women now—post-Roe. Cedar is a pregnant twenty-six-year-old woman living in Minneapolis near both her white adoptive parents and her Ojibwe birth mother. She's writing to her future child, and the reader knows only what Cedar knows, which is very little since the community soon suffers a news blackout and can only exchange rumors. There is a looming apocalypse, and it may include evolutionary reversal. Cedar, whose pregnancy is now showing, is confined to her house because pregnant women are being seized by officers right off the streets under an extension of the Patriot Act. It is now a crime to harbor or help a pregnant woman. Those turning in a pregnant woman (tip line: Unborn Protection Society) receive an award; those who refuse to provide information are tortured. We follow Cedar through her capture, institutional confinement, and escape and pick up fragments of what's happening—using a credit card risks being tracked; prisons are now for pregnant women; Womb Volunteers are now forced to gestate "liberated" embryos; street names have been changed to Bible verses—all this while watching Cedar negotiate her relationships with both families. And despite the absence of a fully realized dystopian world, with all plot points neatly tied off, Erdrich delivers the engrossing plot development and well-developed characters found throughout her body of work. Reading this while watching our rights rolled back, the book's references to evolutionary reversal read less sci-fi and more metaphor. What is this event that's leading to further incursions on a woman's right to bodily autonomy? We don't really know, but in 2022 it's even easier to imagine the possibilities. [End Page 9] Copyright © 2022 World Literature Today and the Board of Regents of the University of Oklahoma

National Assessment of the Relationship Between Tip Line Implementation and School Safety Outcomes

ABSTRACT High-profile school attacks highlight the need for effective school safety solutions. School safety tip lines offer a prevention-based solution. However, little is known about their effectiveness. Using a quasi-experimental multilevel design, we examined the association between school tip-line adoption and violent threats and attacks at school (i.e., sexual assault, robbery, physical attacks with and without a weapon, firearm possession), including 1) the association between having a tip line and the rate and distribution of violent offense types, and 2) for schools with tip lines, whether strategies associated with tip-line implementation were associated with the rate and distribution of violent offense types. Using data from a nationally representative sample of 1,226 public middle and high schools, we conducted multivariable regression models using propensity score weights. Schools with tip lines did not have significantly lower rates of total offenses but were associated with an expected distributional difference: more violent threats and fewer violent attacks. Tip line implementation strategies were mixed. Recommendations for tip-line adoption and implementation are discussed.

Localized direct material removal and deposition by nanoscale field emission scanning probes

The manufactory of advanced micro- and nanoscale devices relies on capable patterning strategies. Focused electron beams, as for instance implemented since long in electron beam lithography and electron beam induced deposition, are in this regard key enabling tools especially at the early stages of device development and research. We show here that nanoscale field emission scanning probes can be potentially utilized as well for a prospective direct device fabrication by localized material deposition but notably, also by localized material removal. Field emission scanning probe processing was specifically realized on 10 nm chromium and 50 nm gold thin film stacks deposited on a (1 × 1) cm 2 fused silica substrate. Localized material deposition and metal removal was studied in various atmospheres comprising high vacuum, nitrogen, ambient air, naphthalene and carbon-dioxide. Stable and reliable regimes were in particular obtained in a carbonaceous atmosphere. Hence, localized carbon deposits were obtained but also localized metal removal was realized. We demonstrate furthermore that the selected electron emission parameters (20 V - 80 V, 180 pA) and the overall operation environment are crucial aspects that determine the degree of material deposition and removal. Based on our findings, direct tip-based micro- to nanoscale material patterning appears possible. The applied energy regime is also enabling new insights into low energy (< 100 eV) electron interaction. However, the underlying mechanisms must be further elucidated. • implementation of field-emission scanning probes to create localized 3D carbonaceous deposits from the gas phase. • demonstration of gold removal below the tip (line scans) by adjusting the experimental conditions. • first exploration of the impact of various atmospheres on the degree of material deposition and removal. • reproducible generation of line patterns by material removal and deposition.

Development of Automatic Crack Growth Simulation Program Based on Finite Element Analysis

A crack growth simulation program based on the advanced iterative-finite element method (AI-FEM) was developed to predict realistic crack growth of structures. The developed program was suggested to calculate the exact stress intensity factor for arbitrary structures by regenerating the crack tip mesh as the crack grows. The main advantages of the developed program are to estimate each different crack growths along the crack tip line and to simulate the cracking transition from a surface crack to a through-wall crack under a complex stress field. For these purposes, the sensitivity analyses were performed for various influence variables on stress intensity factors, such as element types and crack dimensions. Based on the results of sensitivity analyses, the appropriate criteria for crack tip modeling to be used in AI-FEM were suggested to calculate sufficient converged SIF. The program developed in this research was validated through stress corrosion crack growth and natural crack growth examples including cracking transition, and it was confirmed that the program simulates crack growth well and has reasonable methods for cracking transition.

Leakage warning behaviors for mass school violence: An analysis of tips reported to a state school safety tip line.

Leakage warning behaviors for mass school violence: An analysis of tips reported to a state school safety tip line.

Theory of Critical Distances and static/dynamic fracture behaviour of un-reinforced concrete: length scale parameters vs. material meso-structural features

The Theory of Critical Distances (TCD) groups together a number of approaches that make use of specific length scale parameters to model and estimate the strength of cracked/notched engineering materials. In the TCD framework, the critical distance is assumed to be an intrinsic property and this length is somehow related to the material micro-/meso-/macro-structural features. In recent years, a number of comprehensive theoretical/experimental investigations have proven that the TCD is successful also in assessing the static/dynamic Mode I/Mixed-Mode I-II strength of unreinforced concrete containing geometrical features of all kinds. However, the scientific community has not yet agreed on a commonly accepted answer to the most obvious fundamental research question, i.e. “what is the physical meaning of the TCD critical distance?” In order to answer this question, a number of experimental results were generated by testing specimens of unreinforced concrete under static and dynamic Mode I bending. According to what is recommended by RILEM for the determination of fracture parameters of plain concrete, this comprehensive experimental work involved not only plain samples, but also specimens containing crack-like saw-cut notches. The specimens being tested were manufactured by using different bespoke mixes so that the meso-structural features of the concrete materials being tested could be controlled and then modelled in a very accurate way. The results from this systematic experimental/theoretical study led to the conclusion that the TCD critical length approaches the average distance between the crack-like saw-cut notch tip line and the first aggregates, with these aggregates acting as barriers slowing down/affecting the crack propagation process.

Role of Venous Endothelial Cells in Developmental and Pathologic Angiogenesis

Angiogenesis is a dynamic process that involves expansion of a preexisting vascular network that can occur in a number of physiological and pathological settings. Despite its importance, the origin of the new angiogenic vasculature is poorly defined. In particular, the primary subtype of endothelial cells (capillary, venous, arterial) driving this process remains undefined. Endothelial cells were fate-mapped with the use of genetic markers specific to arterial and capillary cells. In addition, we identified a novel venous endothelial marker gene (Gm5127) and used it to generate inducible venous endothelium-specific Cre and Dre driver mouse lines. Contributions of these various types of endothelial cells to angiogenesis were examined during normal postnatal development and in disease-specific setting. Using a comprehensive set of endothelial subtype-specific inducible reporter mice, including tip, arterial, and venous endothelial reporter lines, we showed that venous endothelial cells are the primary endothelial subtype responsible for the expansion of an angiogenic vascular network. During physiological angiogenesis, venous endothelial cells proliferate, migrating against the blood flow and differentiating into tip, capillary, and arterial endothelial cells of the new vasculature. Using intravital 2-photon imaging, we observed venous endothelial cells migrating against the blood flow to form new blood vessels. Venous endothelial cell migration also plays a key role in pathological angiogenesis. This was observed both in formation of arteriovenous malformations in mice with inducible endothelium-specific Smad4 deletion mice and in pathological vessel growth seen in oxygen-induced retinopathy. Our studies establish that venous endothelial cells are the primary endothelial subtype responsible for normal expansion of vascular networks, formation of arteriovenous malformations, and pathological angiogenesis. These observations highlight the central role of the venous endothelium in normal development and disease pathogenesis.

Analyses of the effects of persistent subretinal fluid on visual/anatomic outcomes according to the type of macular neovascularization during the relaxed treat-and-extend protocol in age-related macular degeneration patients

BackgroundTo analyze the long-term effects of persistent subretinal fluid (SRF) on visual/anatomic outcomes according to the type of macular neovascularization (MNV) during relaxed treat-and-extend regimen with anti-vascular endothelial growth factor (anti-VEGF) agents in age-related macular degeneration (AMD) patients.MethodsPatients with fovea-involving type 1 or type 2 MNV, treated with a relaxed treat-and-extend regimen for 2 years were retrospectively reviewed. Eyes with SRF observed more than three times per year were defined as the ‘persistent SRF (+) group’. To exclude the effects of IRF as much as possible, the eyes with persistent IRF were excluded. The effects of persistent SRF on the best-corrected visual acuity (BCVA), central subfield retinal thickness (CST), and changes in the photoreceptor layer (PRL) thickness and outer retinal bands (external limiting membrane, ellipsoid zone, and cone outer segment tip line) after anti-VEGF injection were analyzed for each MNV type.ResultsSeventy-seven eyes with type 1 MNV (44 eyes with persistent SRF) and 53 eyes with type 2 MNV (18 eyes with persistent SRF) were enrolled. Following a relaxed treat-and-extend regimen with anti-VEGF agents, BCVA and CST improved for each MNV type. In comparison between persistent SRF (+) and persistent SRF (−) group, there were no differences in the amount of change in BCVA and CST between the two groups for each MNV type during 2-year follow-up periods. In addition, there were no differences in the amount of reduction in PRL thickness and state of the outer retinal bands between the two groups for each MNV type.ConclusionsUsing a relaxed treat-and-extend regimen with anti-VEGF agents, persistent SRF did not have additional effects on visual and anatomic outcomes by 2 years, regardless of the MNV type.

Evaluating a statewide anonymous reporting system for students and multidisciplinary response teams: Methods for a randomized trial

Schools throughout the country are seeking effective ways to prevent a wide array of events that may pose physical, mental, and social threats to students and staff. The Nevada Departments of Education and Public Safety are implementing a statewide anonymous tip line for students to report potentially harmful events, supported by multi-disciplinary teams in all schools and local law enforcement agencies to respond and follow up accordingly. The paper describes the research team's methods to assess implementation and outcomes, using a multi-method research approach that includes the collection of program data about tips and responses, annual surveys of multi-disciplinary teams, interviews and focus groups with local stakeholders, and the collection of district-level extant data.

Preparation and Performance of an Abradable NiCrFeAlBN-YSZ-NiCrAl Layered Seal Coating for Aircraft Engines

Ti2AlNb alloys are often used to fabricate high-pressure compressor blades and casings in aircraft engines with high thrust/weight ratios. In this study, a three-layered seal coating, NiCrFeAlBN-YSZ-NiCrAl, was prepared by thermal spraying on a titanium alloy (Ti2AlNb) substrate. The microstructure, surface hardness, and bond strength of coatings as well as their thermal cycling performance and abradability under simulated working conditions were investigated. The coating surface hardness was 61 HR15Y and the bond strength was 7.13 MPa. The coating maintained a good bonding to the substrate with no cracks after 40 cycles of water-cooling from 750 °C to room temperature. The abradability of the as-sprayed coating and the coating heat-treated at 750 °C for 200 h was tested against a Ti2AlNb blade at 750 °C, with a tip line speed of 300 m/s, and feed rates of 5, 50 and 480 m/s. The coating wear mechanisms involved micro-ruptures. The Cr2O3 phase formation and a decrease in the number of micropores in the heat-treated coating decreased its abradability.

Changes of outer retinal thickness with increasing age in normal eyes

AIM: To comprehensively investigate the relationship between outer retinal layer thickness and age in normal eyes. METHODS: One hundred normal eyes of 100 subjects who underwent spectral-domain optical coherence tomography (SD-OCT) were included in this retrospective study. The distances between the external limiting membrane (ELM) line and the photoreceptor inner segment/outer segment (IS/OS) line (ELM-IS/OS), the IS/OS line and the cone outer segment tips (COST) line (IS/OS-COST), the COST line and the retinal pigment epithelium (RPE) complex (COST-RPE) and the full retinal thickness (RT) were measured at the fovea and on four quarters. The relationship between thickness and age or sex was then analysed. CONCLUSION: In normal eyes, the RT thickness on the nasal quarter and the ELM-IS/OS thickness were significantly and negatively correlated with age. The IS/OS-COST and COST-RPE thicknesses were not significantly correlated with age or sex.

Have you Heard? Newsworthy items from the field

The Education Commission of the States analyzed governors’ 2020 State of the State addresses to determines what their priorities are for education. ACT’s Center for Equity in Learning surveyed students who took the February 2019 ACT exam about their perceptions of current mental health services at their schools. RTI International surveyed principals from 1,226 schools about tip lines where students, families, and community members can report potential school safety concerns. A publication from the National Center of Education Statistics looks at school start times.

X-ray and Computed Tomography Scan-Based Morphometric Analysis of Skull Baselines in Indian Population.

Introduction:The study aims at providing an overview of morphometric measurements of the skull baselines in normal Indian population and compares these dimensions with those of other races and ethnicities. This study will help in defining “normal” baseline values for Indian population. It will also compare dimensions as measured on X-ray and computed tomography (CT) scan to assess the reliability of X-ray as a diagnostic modality for the assessment of the skull baselines in Indian population.Materials and Methods:Retrospective study with a sample size of 116 patients and duration of 30 months.Results:The mean value for distance between dens tip and Chamberlain line on CT was 0.498 mm and on X-ray was 0.528 mm and for the distance between dens tip and McGregor line on CT was 0.213 mm and on X-ray was 0.228 mm. The mean distance between the dens tip and McRae line was 4.67 1.69 mm on CT scan and 4.7 1.76 mm on X-ray.Conclusion:There was not a single patient in whom the dens tip crossed the McRae line. Any protrusion of the dens tip beyond the foramen magnum is abnormal. Hence, the McRae line is easiest to understand and remember. Furthermore, the Chamberlain and McGregor lines rely on identifying the hard palate, which may not be included in routine X-ray, CT, and magnetic resonance imaging studies depend on the field of view. Hence, we recommend the use of McRae line for screening purposes while evaluating pathologies of the craniovertebral junction. X-ray is a reliable diagnostic technique for assessing morphometry of the skull baselines in an emergency or rural setting if facility for CT scan is not available.