Population assessment of the vermilion snapper, Rhomboplites aurorubens, from the Southeastern United States

Changes in the age structure and population size of vermilion snapper, Rhornboplites aurorubens, from North Carolina through the Florida Keys were examined using records of landings and size frequencies of fish from commercial, recreational, and headboat fisheries from 1986-1996. Population size in numbers at age was estimated for each year by applying separable virtual population analysis (SVPA) to the landings in numbers at age. SVPA was used to estimate annual, age-specific fishing mortality (F) for four levels of natural mortality (M = 0.20, 0.25, 0.30, and 0.35). Although landings of vermilion snapper for the three fisheries have declined, minimum fish size regulations have resulted in an increase in the mean size of fish landed. Age at entry and age at full recruitment were age-1 andage-3 fDr 1986-1991, compared with age-1 and age-4, respectively, for 1992-1996. Levels of mortality from fishing (F) ranged from 0.38 - 0.61 for the entire period. Current spawning potential ratio (SPR) is 21% or 27% depending on the natural mortality estimate. SPR could be raised to 30% or 40% with a reduction in F, or by increasing the age at entry to the fisheries. The latter could be enhanced now if fishermen, particularly recreational, comply with minimum size regulations. However, released fish mortality, modeled in the assessment at 27%, will continue to make the achievement of 30% and 40% SPR more difficult. (PDF contains 63 pages

Nonlinear stabilitty for steady vortex pairs

In this article, we prove nonlinear orbital stability for steadily translating vortex pairs, a family of nonlinear waves that are exact solutions of the incompressible, two-dimensional Euler equations. We use an adaptation of Kelvin's variational principle, maximizing kinetic energy penalised by a multiple of momentum among mirror-symmetric isovortical rearrangements. This formulation has the advantage that the functional to be maximized and the constraint set are both invariant under the flow of the time-dependent Euler equations, and this observation is used strongly in the analysis. Previous work on existence yields a wide class of examples to which our result applies.Comment: 25 page

Providing Foundations for an Educational Revolution: Moving Towards an Integrated Perspective

The pandemic of Spring 2020 necessitated a rapid switch in teaching methods around the world. Most significantly was the revolutionary transition from face to face instruction to remote, distance, or virtual teaching/learning and the resultant online “new normal” that continues to ripple across the academy and society at large. This new reality has necessitated a paradigmatic shift in how scholars, teachers and administrators understand, create, employ, and assess teaching/learning. It has likewise resulted in a shift in how students, parents, families, and employers understand, value, desire, and prefer educational formats and settings. The authors point to the importance of considering aspects of theory, research, and best practices related to this transition. The article surveys resulting first response scholarship and forecast types of questions that loom large regarding the practice of online teaching in the new economic, academic, social framework

Eyewitnesses to the Suddenly Online Paradigm Shift in Education: Perspectives on the Experience, Sustaining Effective Teaching and Learning, and Forecasts for the Future

Introducing this special issue of the Journal of Literacy and Technology, the second part of the two-part special issues focusing on the COVID-19 “suddenly online” transition to remote/virtual eLearning modalities during the Spring of 2020. This article introduces the emergency voices from the field arising from the COVID-19 “suddenly online” transition to remote/virtual eLearning modalities during the Spring of 2020. This rare, and perhaps “once in a lifetime” momentous COVID-19 pandemic induced a paradigmatic shift in teaching and learning modalities. The first-hand eyewitness accounts which emerged from the turbulent months of the “suddenly online” transition in education are important to capture direct reports from participant observers of the experience. That in this case, many of these participant-observers are also trained educators, academic researchers, and able to provide meta-perspectives on those experiences makes recollections, reports, and perspectives even more remarkable and essential

Potential Vorticity Evolution of a Protoplanetary Disk with An Embedded Protoplanet

We present two-dimensional inviscid hydrodynamic simulations of a protoplanetary disk with an embedded planet, emphasizing the evolution of potential vorticity (the ratio of vorticity to density) and its dependence on numerical resolutions. By analyzing the structure of spiral shocks made by the planet, we show that progressive changes of the potential vorticity caused by spiral shocks ultimately lead to the excitation of a secondary instability. We also demonstrate that very high numerical resolution is required to both follow the potential vorticity changes and identify the location where the secondary instability is first excited. Low-resolution results are shown to give the wrong location. We establish the robustness of a secondary instability and its impact on the torque onto the planet. After the saturation of the instability, the disk shows large-scale non-axisymmetry, causing the torque on the planet to oscillate with large amplitude. The impact of the oscillating torque on the protoplanet's migration remains to be investigated.Comment: 17 pages total with 9 figures (Fig.4,5,9 are in .jpg), accepted to Ap

Stoichiometry and thickness dependence of superconducting properties of niobium nitride thin films

The current technology used in linear particle accelerators is based on superconducting radio frequency (SRF) cavities fabricated from bulk niobium (Nb), which have smaller surface resistance and therefore dissipate less energy than traditional nonsuperconducting copper cavities. Using bulk Nb for the cavities has several advantages, which are discussed elsewhere; however, such SRF cavities have a material-dependent accelerating gradient limit. In order to overcome this fundamental limit, a multilayered coating has been proposed using layers of insulating and superconducting material applied to the interior surface of the cavity. The key to this multilayered model is to use superconducting thin films to exploit the potential field enhancement when these films are thinner than their London penetration depth. Such field enhancement has been demonstrated in MgB2 thin films; here, the authors consider films of another type-II superconductor, niobium nitride (NbN). The authors present their work correlating stoichiometry and superconducting properties in NbN thin films and discuss the thickness dependence of their superconducting properties, which is important for their potential use in the proposed multilayer structure. While there are some previous studies on the relationship between stoichiometry and critical temperature T-C, the authors are the first to report on the correlation between stoichiometry and the lower critical field H-C1. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)

Evaluation of Online Consumer Health Information for Idiopathic Scoliosis Identified by a Google Search

Introduction. This study sought to assess the quality of online consumerhealth information about idiopathic scoliosis. Previous studiesshowed that quality of online health information varies and oftenlacks adherence to expert recommendations and guidelines. Nevertheless,72% of internet users seek health information online. A 2005analysis of online scoliosis information found that the informationwas limited and of poor quality. Methods. Two reviewers vetted the top 10 websites resulting from aGoogleTM search for “scoliosis.” Content was organized into categoriesand rated by three physician evaluators using a 1 - 5 scale basedon quality, accuracy, completeness of information, readability, andwillingness to recommend. Additional information, such as numberof ads and Flesch-Kinkaid reading level, also was collected. Results. The average overall physician score was 47.6 (75 possible).All websites included content that was mostly accurate but varied incompleteness. Physicians unanimously recommended Mayo Clinic,MedicineNet, and Kids Health; none recommended the GoogleTMKnowledge Graph. The Scoliosis Research Society website reachedthe highest overall physician score. Readability ranged from 7th gradeto college level; only that of Kids Health was below 10th grade level. Conclusions. Most essential information provided by the websiteswas accurate and generally well rated by physicians. Website rankingby physicians was inconsistent with the ranking order by GoogleTM,indicating that health seekers reviewing the top GoogleTM-rankedwebsites may not be viewing the websites rated highest by physicians.Physicians should consider patient literacy in website recommendations,as many have an above average literacy level.Kans J Med 2018;11(4):95-101

Cervical, Thoracic, and Spinopelvic Compensation After Proximal Junctional Kyphosis (PJK): Does Location of PJK Matter?

Study Design:Retrospective case series. Objective:Compensatory changes above a proximal junctional kyphosis (PJK) have not been defined. Understanding these mechanisms may help determine optimal level selection when performing revision for PJK. This study investigates how varying PJK location changes proximal spinal alignment. Methods:Patients were grouped by upper instrumented vertebrae (UIV): lower thoracic (LT; T8-L1) or upper thoracic (UT; T1-7). Alignment parameters were compared. Correlation analysis was performed between PJK magnitude and global/cervical alignment. Results:A total of 369 patients were included; mean age of 63 years, body mass index 28, and 81% female, LT (n = 193) versus UT (n = 176). The rate of radiographic PJK was 49%, higher in the LT group (55% vs 42%, P = .01). The UT group displayed significant differences in all cervical radiographic parameters (P < .05) between PJK versus non-PJK patients, while the LT group displayed significant differences in T1S and C2-T3 sagittal vertical axis (SVA) (CTS). In comparing UT versus LT patients, UT had more posterior global alignment (smaller TPA [T1 pelvic angle], SVA, and larger PT [pelvic tilt]) and larger anterior cervical alignment (greater cSVA [cervical SVA], T1S-CL [T1 slope-cervical lordosis] mismatch, CTS) compared to LT. Correlation analysis of PJK magnitude and location demonstrated a correlation with increases in CL, T1S, and CTS in the UT group. In the LT group, PT increased with PJK angle (r = 0.17) and no significant correlations were noted to SVA, cSVA, or T1S-CL. Conclusions:PJK location influences compensation mechanisms of the cervical and thoracic spine. LT PJK results in increased PT and CL with decreased CTS. UT PJK increases CL to counter increases in T1S with continued T1S-CL mismatch and elevated cSVA

Acute Reciprocal Changes Distant from the Site of Spinal Osteotomies Affect Global Postoperative Alignment

Introduction. Three-column vertebral resections are frequently applied to correct sagittal malalignment; their effects on distant unfused levels need to be understood. Methods. 134 consecutive adult PSO patients were included (29 thoracic, 105 lumbar). Radiographic analysis included pre- and postoperative regional curvatures and pelvic parameters, with paired independent t-tests to evaluate changes. Results. A thoracic osteotomy with limited fusion leads to a correction of the kyphosis and to a spontaneous decrease of the unfused lumbar lordosis (−8°). When the fusion was extended, the lumbar lordosis increased (+8°). A lumbar osteotomy with limited fusion leads to a correction of the lumbar lordosis and to a spontaneous increase of the unfused thoracic kyphosis (+13°). When the fusion was extended, the thoracic kyphosis increased by 6°. Conclusion. Data from this study suggest that lumbar and thoracic resection leads to reciprocal changes in unfused segments and requires consideration beyond focal corrections

Topological Orthoalgebras

We define topological orthoalgebras (TOAs) and study their properties. While every topological orthomodular lattice is a TOA, the lattice of projections of a Hilbert space is an example of a lattice-ordered TOA that is not a toplogical lattice. On the other hand, we show that every compact Boolean TOA is a topological Boolean algebra. We also show that a compact TOA in which 0 is an isolated point is atomic and of finite height. We identify and study a particularly tractable class of TOAs, which we call {\em stably ordered}: those in which the upper-set generated by an open set is open. This includes all topological OMLs, and also the projection lattices of Hilbert spaces. Finally, we obtain a topological version of the Foulis-Randall representation theory for stably ordered TOAsComment: 16 pp, LaTex. Minor changes and corrections in sections 1; more substantial corrections in section