Bilateral papillitis and unilateral focal chorioretinitis as the presenting features of syphilis.

BACKGROUND: Syphilis is a multisystem bacterial infection caused by Treponema pallidum. The incidence of infection in the United States has risen by more than 75% since the year 2000, when it was at a low of 2.1 per 100,000 people. Ocular involvement may occur in any stage of infection and may present in a variety of ways, with posterior uveitis being the most common manifestation. We report a case of ocular syphilis infection with an unusual presentation of bilateral non-granulomatous panuveitis with papillitis and unilateral focal chorioretinitis. FINDINGS: This is a retrospective case report with literature review. A 39-year-old Caucasian female presented with a 2-week history of bilateral ocular flashes and left eye pain. Dilated fundus examination revealed mild optic disc edema in both eyes, the right eye more than the left. In the left eye, there was an area of retinal elevation and whitening involving the peripheral retina. Fluorescein angiography, B-scan ultrasonography, and ocular coherence tomography were performed, and laboratory tests were ordered based on the clinical presentation. After rapid plasma reagin (RPR) and fluorescent treponemal antibody absorption (FTA-Abs) were positive, syphilitic uveitis was confirmed, and the patient was admitted for a 14-day course of high-dose intravenous penicillin G. CONCLUSIONS: The first signs and symptoms of syphilis may be ocular, which can lead to a diagnostic challenge. A high index of suspicion is the key for early diagnosis of ocular syphilis. Prompt treatment with intravenous penicillin G is highly effective in resolving the infection

Neutron skin of 208^{208}Pb from Coherent Pion Photoproduction

Information on the size and shape of the neutron skin on $^{208}$Pb has been extracted from coherent pion photoproduction cross sections measured using the Crystal Ball together with the Glasgow tagger at the MAMI electron beam facility. On exploitation of an interpolated fit of a theoretical model to the measured cross sections the half-height radius and diffuseness of the neutron distribution are found to be 6.70$\pm 0.03(stat)$ fm and 0.55$\pm 0.01(stat)$$^{+0.02}_{-0.03}(sys)$ fm respectively, corresponding to a neutron skin thickness $\Delta r_{np}$=0.15$\pm 0.03(stat)$$^{+0.01}_{-0.03}(sys)$ fm. The results give the first successful extraction of a neutron skin with an electromagnetic probe and indicate the skin of $^{208}$Pb has a halo character. The measurement provides valuable new constraints on both the structure of nuclei and the equation of state for neutron-rich matter.Comment: 4 figures 5 pages. Version submitted to journal. Includes additional studies of systematic effects in the extracted diffuseness, which led to a small increase in the quoted systematic error. These additional studies are discussed in the revised manuscript. Also includes minor editorial improvements to the tex

Rapid migration from traditional or hybrid to fully virtual education in the age of the coronavirus pandemic: challenges, experiences and views of college and university students

The abrupt outbreak of the coronavirus pandemic throughout the world in March 2020 resulted in the sudden closure of all schools, colleges and universities, institutions, and an unprecedented pivot to remote learning. Students and teachers were confronted with the overwhelming challenge of migrating from the traditional face-to-face or hybrid mode of education to fully virtual learning and assessment environments within an extremely short amount of time. This migration was exceptionally difficult, as it took place halfway through the academic or school year in most countries. While pandemic restrictions currently vary across different regions, the 2020-2021 academic session continues to pose challenges despite the experience gained. In addition to a review of the current state-of-the-art in relation to the effects of COVID-19 on teaching and learning, this paper reports on an empirical study carried out in 26 countries (from Asia, Europe, Africa and America), by 36 academics from 29 academic institutions. Through an extensive global survey of college and university students, information was collected about the challenges (technological, economic, psychological) faced by them, as a result of the pandemic. We also asked the students’ to offer their ideas and suggestions for further improvements in teaching and learning, as we look toward a post-COVID world. In this paper, we address issues relating to the availability of, and accessibility to, necessary digital technologies (e.g., learning and communication platforms), isolation, disconnection, and loneliness among students, the overall impact of the pandemic on learning and academic performance, and the reliability of assessment methods., cybercrime dangers and fake information. A total of 1005 responses to the survey were received and analysed. The results are presented in this paper together with reflections of the authors. The paper concludes with a summary of suggestions for process improvements in distance education, and the need for preventive preparedness in the post-COVID period

Molecular Characterization of the Gastrula in the Turtle Emys orbicularis: An Evolutionary Perspective on Gastrulation

Due to the presence of a blastopore as in amphibians, the turtle has been suggested to exemplify a transition form from an amphibian- to an avian-type gastrulation pattern. In order to test this hypothesis and gain insight into the emergence of the unique characteristics of amniotes during gastrulation, we have performed the first molecular characterization of the gastrula in a reptile, the turtle Emys orbicularis. The study of Brachyury, Lim1, Otx2 and Otx5 expression patterns points to a highly conserved dynamic of expression with amniote model organisms and makes it possible to identify the site of mesoderm internalization, which is a long-standing issue in reptiles. Analysis of Brachyury expression also highlights the presence of two distinct phases, less easily recognizable in model organisms and respectively characterized by an early ring-shaped and a later bilateral symmetrical territory. Systematic comparisons with tetrapod model organisms lead to new insights into the relationships of the blastopore/blastoporal plate system shared by all reptiles, with the blastopore of amphibians and the primitive streak of birds and mammals. The biphasic Brachyury expression pattern is also consistent with recent models of emergence of bilateral symmetry, which raises the question of its evolutionary significance

On directed interacting animals and directed percolation

We study the phase diagram of fully directed lattice animals with nearest-neighbour interactions on the square lattice. This model comprises several interesting ensembles (directed site and bond trees, bond animals, strongly embeddable animals) as special cases and its collapse transition is equivalent to a directed bond percolation threshold. Precise estimates for the animal size exponents in the different phases and for the critical fugacities of these special ensembles are obtained from a phenomenological renormalization group analysis of the correlation lengths for strips of width up to n=17. The crossover region in the vicinity of the collapse transition is analyzed in detail and the crossover exponent $\phi$ is determined directly from the singular part of the free energy. We show using scaling arguments and an exact relation due to Dhar that $\phi$ is equal to the Fisher exponent $\sigma$ governing the size distribution of large directed percolation clusters.Comment: 23 pages, 3 figures; J. Phys. A 35 (2002) 272

Challenges of rapid migration to fully virtual education in the age of the Corona virus pandemic: experiences from across the world

The social disruption caused by the sudden eruption of the Corona Virus pandemic has shaken the whole world, influencing all levels of education immensely. Notwithstanding there was a lack of preparedness for this global public health emergency which continues to affect all aspects of work and life. The problem is, naturally, multifaceted, fast evolving and complex, affecting everyone, threatening our well-being, the global economy, the environment and all societal and cultural norms and our everyday activities. In a recent UNESCO report it is noted that nearly a billion and a quarter (which is 67,7 % of the total number) of learners have been affected by the Corona Virus pandemic worldwide. The education sector at all levels has been one of the hardest hit sectors particularly as the academic/school year was in full swing. The impact of the pandemic is widespread, representing a health hazard worldwide. Being such, it profoundly affects society as a whole, and its members that are, in particular, i) individuals (the learners, their parents, educators, support staff), ii) schools, training organisations, pedagogical institutions and education systems, iii) quickly transformed policies, methods and pedagogies to serve the newly appeared needs of the latter. Lengthy developments of such scale usually take years of consultation, strategic planning and implementation. In addition to raising awareness across the population of the dangers of the virus transmission and instigating total lockdown, it has been necessary to develop mechanisms for continuing the delivery of education as well as demanding mechanisms for assuring the quality of the educational experience and educational results. There is often scepticism about securing quality standards in such a fast moving situation. Often in the recent past, the perception was that courses and degrees leading to an award are inferior if the course modules (and sometimes its assessment components) were wholly online. Over the last three decades most Higher Education institutions developed both considerable infrastructure and knowhow enabling distance mode delivery schools (Primary and Secondary) had hardly any necessary infrastructure nor adequate knowhow for enabling virtual education. In addition, community education and various training providers were mainly delivered face-to-face and that had to either stop altogether or rapidly convert materials, exercises and tests for online delivery and testing. A high degree of flexibility and commitment was demanded of all involved and particularly from the educators, who undertook to produce new educational materials in order to provide online support to pupils and students. Apart from the delivery mode of education, which is serving for certificated programmes, it is essential to ensure that learners’ needs are thoroughly and continuously addressed and are efficiently supported throughout the Coronavirus or any other future lockdown. The latter can be originated by various causes and reasons that vary in nature, such as natural or socioeconomical. Readiness, thus, in addition to preparedness, is the primary key question and solution when it comes to quality education for any lockdown. In most countries, the compulsory primary and secondary education sectors have been facing a more difficult challenge than that faced by Higher Education. The poor or in many cases non-existent technological infrastructure and low technological expertise of the teachers, instructors and parents, make the delivery of virtual education difficult or even impossible. The latter, coupled with phenomena such as social exclusion and digital divide where thousands of households do not have adequate access to broadband Internet, Wi-Fi infrastructure and personal computers hamper the promising and strenuous virtual solutions. The shockwaves of the sudden demands on all sectors of society and on individuals required rapid decisions and actions. We will not attempt to answer the question “Why was the world unprepared for the onslaught of the Coronavirus pandemic” but need to ascertain the level of preparedness and readiness particularly of the education sector, to effect the required rapid transition. We aimed to identify the challenges, and problems faced by the educators and their institutions. Through first-hand experiences we also identify best practices and solutions reached. Thus we constructed a questionnaire to gather our own responses but also experiences from colleagues and members of our environment, family, friends, and colleagues. This paper reports the first-hand experiences and knowledge of 33 co-authors from 27 institutions and from 13 different countries from Europe, Asia, and Africa. The communication technologies and development platforms used are identified; the challenges faced as well as solutions and best practices are reported. The findings are consolidated into the four areas explored i.e. Development Platforms, Communications Technologies, Challenges/Problems and Solutions/Best Practices. The conclusion summarises the findings into emerging themes and similarities. Reflections on the lasting impact of the effect of Coronavirus on education, limitations of study, and indications of future work complete the paper

On the V-type asteroids outside the Vesta family. I. Interplay of nonlinear secular resonances and the Yarkovsky effect: the cases of 956 Elisa and 809 Lundia

Among the largest objects in the main belt, asteroid 4 Vesta is unique in showing a basaltic crust. It is also the biggest member of the Vesta family, which is supposed to originate from a large cratering event about 1 Gyr ago (Marzari et al. 1996). Most of the members of the Vesta family for which a spectral classification is available show a V-type spectra. Before the discovery of 1459 Magnya (Lazzaro et al. 2000) and of several V-type NEA (Xu 1995), all the known V-type asteroids were members of the Vesta family. Recently two V-type asteroids, 809 Lundia and 956 Elisa, (Florczak et al. 2002) have been discovered well outside the limits of the family, near the Flora family. We currently know 22 V-type asteroids outside the family, in the inner asteroid belt. In this work we investigate the possibility that these objects are former family members that migrated to their current positions via the interplay of Yarkovsky effect and nonlinear secular resonances. The main dynamical feature of 956 Elisa and 809 Lundia is that they are currently inside the 2(g-g6)+s-s6 (z2 by Milani and Knezevic, 1993) secular resonance. Our investigations show that members of the Vesta dynamical family may drift in three-body and weak secular resonances until they are captured in the strong z2 secular resonance. Only asteroids with diameters larger than 16 km can remain in one of the three-body or secular resonances long enough to reach the region of the z2 resonance. This two-step mechanism of capture into the z2 resonance could explain: i) the current resonant orbits of 956 Elisa and 809 Lundia, ii) why their size is significantly larger than that of the typical member of the Vesta family, and iii) provide a lower limit on the Vesta family age.Comment: 14 pages, 10 figures, 3 tables. Accepted for publication in A&

Coherent photoproduction of π0- and η-mesons off 7Li

Abstract.: Coherent photoproduction of π0-mesons from threshold (E th ≈ 136 MeV) throughout the Δ-resonance region and of η-mesons close to the production threshold (E th ≈ 570 MeV for η has been measured for 7Li nuclei. The experiment was performed using the tagged-photon beam of the Mainz MAMI accelerator with the Crystal Ball and TAPS detectors combined to give an almost 4π solid-angle electromagnetic calorimeter. The reactions were identified by a combined invariant-mass and missing-energy analysis. A comparison of the pion data to plane-wave impulse modelling tests the nuclear mass form factor. So far coherent η production had been only identified for the lightest nuclear systems (2H and 3He . For 3He a large enhancement of the cross section above plane-wave approximations had been reported, indicating the formation of a quasi-bound state. The present Li data for η production agree with a plane-wave approximation. Contrary to 3He , neither a threshold enhancement of the total cross section nor a deviation of the angular distributions from the expected form factor dependence were observe