1,387 research outputs found

    Sexual differentiation and gonad development in striped mullet (Mugil cephalus L.) from South Carolina estuaries*

    Get PDF
    This study examined the sexual differentiation and reproductive dynamics of striped mullet (Mugil cephalus L.) in the estuaries of South Carolina. A total of 16,464 specimens were captured during the study and histological examination of sex and maturity was performed on a subsample of 3670 fish. Striped mullet were sexually undifferentiated for the first 12 months, began differentiation at 13 months, and were 90% fully differentiated by 15 to 19 months of age and 225 mm total length (TL). The defining morphological characteristics for differentiating males was the elongation of the protogonial germ tissue in a corradiating pattern towards the center of the lobe, the development of primary and secondary ducts, and the lack of any recognizable ovarian wall structure. The defining female characteristics were the formation of protogonial germ tissue into spherical germ cell nests, separation of a tissue layer from the outer epithelial layer of the lobe-forming ovarian walls, a tissue bud growing from the suspensory tissue that helped form the ovary wall, and the proliferation of oogonia and oocytes. Sexual maturation in male striped mullet first occurred at 1 year and 248 mm TL and 100% maturity occurred at age 2 and 300 mm TL. Female striped mullet first matured at 2 years and 291 mm total length and 100% maturity occurred at 400 mm TL and age 4. Because of the open ocean spawning behavior of striped mullet, all stages of maturity were observed in males and females except for functionally mature females with hydrated oocytes. The spawning season for striped mullet recruiting to South Carolina estuaries lasts from October to April; the majority of spawning activity, however, occurs from November to January. Ovarian atresia was observed to have four distinct phases. This study presents morpholog ical analysis of reproductive ontogeny in relation to size and age in South Carolina striped mullet. Because of the length of the undifferentiated gonad stage in juvenile striped mullet, previous studies have proposed the possibility of protandric hermaphrodism in this species. The results of our study indicate that striped mullet are gonochoristic but capable of exhibiting nonfunctional hermaphroditic characteristics in differentiated mature gonads

    Two Departments, Two Models of Interdisciplinary Peer Learning

    Get PDF
    On graduation, teacher candidates (TCs) are typically underprepared to teach science, particularly physical science, whereas physics graduates frequently lack training in teaching or effective communication. In response, we created two models for interdisciplinary peer learning where TCs were paired with either graduate or undergraduate physics students. In both models, physics students teach TCs content knowledge relevant to a given area of either classical or quantum physics, which TCs then use to design and implement a short lesson for K-5 students. Overall, both models were successful, with the two sets of students reporting benefits in each case. Affordances for TCs included increased confidence to teach physical science and an appreciation for collaboration with experts. Physics students described increased awareness of the complexities of communicating science to general audiences and stronger community with their classmates. Students from both groups cited insufficient project time as a constraint, whereas physics students found it challenging to align their project and coursework. In moving away from traditional lecture, these interdisciplinary collaborations also benefitted us as instructors, giving us new perspectives on teaching. In light of our findings we propose improvements to these proof-of-concept models to enable their future scale-up and replication in other disciplines

    Using The-Math-You-Need modules in a general education, oceanography course

    Get PDF
    The Math You Need (TMYN) is a series of on-line tutorials designed for students to increase their mathematical abilities while taking geology and other science courses. The aim of the program is to increase the quantitative abilities of students while demonstrating mathematical applications in an effort to make students more comfortable with and aware of the utility of mathematics. Over two semesters, we implemented targeted-TMYN modules into a general-education oceanography course that is typically populated by non-science majors with a wide variety of mathematical skills before calculus. Students participate voluntarily in TMYN modules with extra credit given for their successful completion. Every class day in the course involves exercises and/or a laboratory that applies oceanographic concepts into which we frequently weave elementary mathematics; also, quantitative questions appear on course exams. For example, understanding rates is particularly fundamental, so exercises frequently concentrate on rate calculations and re-arrangement of simple rate equations and this in-class instruction is complemented by appropriate TMYN modules. To reinforce the importance and utility of mathematics, the instructor continually makes connections between course material and TMYN tutorials. Pedagogical results are mostly positive. Because participation in TMYN modules is voluntary, two-thirds of students participate partially or wholly in the modules; the complementary fraction do not access a single module. We use pre- and post-tests to recognize gains in student mathematical competence. About one third of students either have lower or no change in performance whereas the balance exhibit varying gains. Some students’ scores saltate markedly by doubling, whereas other students achieve more modest gains. Not surprisingly, larger gains tend to be seen by students that have completed more modules with better scores, but this tendency is not absolute. TMYN modules are looked upon favorably by students. The preponderance of students think that TMYN modules improved their mathematical abilities and helped with the class. We plan continued use of TMYN modules with the goal of augmenting student participation, in anticipation of associated improvement in quantitative skills

    Compressed sensing quantum process tomography for superconducting quantum gates

    Full text link
    We apply the method of compressed sensing (CS) quantum process tomography (QPT) to characterize quantum gates based on superconducting Xmon and phase qubits. Using experimental data for a two-qubit controlled-Z gate, we obtain an estimate for the process matrix χ\chi with reasonably high fidelity compared to full QPT, but using a significantly reduced set of initial states and measurement configurations. We show that the CS method still works when the amount of used data is so small that the standard QPT would have an underdetermined system of equations. We also apply the CS method to the analysis of the three-qubit Toffoli gate with numerically added noise, and similarly show that the method works well for a substantially reduced set of data. For the CS calculations we use two different bases in which the process matrix χ\chi is approximately sparse, and show that the resulting estimates of the process matrices match each ther with reasonably high fidelity. For both two-qubit and three-qubit gates, we characterize the quantum process by not only its process matrix and fidelity, but also by the corresponding standard deviation, defined via variation of the state fidelity for different initial states.Comment: 16 pages, 11 figure

    Assessing the Sociology of Sport: On the Trajectory, Challenges, and Future of the Field

    Get PDF
    This document is the Accepted Manuscript version of the following article: Elizabeth C. J. Pike, Steven J. Jackson, and Lawrence A. Wenner, 'Assessing the sociology of sport: On the trajectory, challenges, and future of the field'. The final, definitive version of this paper has been published in International Review for the Sociology of Sport, Vol. 50 (4-5), May 2015, doi: https://doi.org/10.1177/1012690215574127, published by SAGE Publishing, All rights reserved. © The Author(s) 2015.On the fiftieth anniversary of the International Sociology of Sport Association and the International Review for the Sociology of Sport, the three guest editors for this special fiftieth anniversary issue of the IRSS, current ISSA president, Elizabeth CJ Pike, the immediate past president, Steven J Jackson, and current IRSS editor, Lawrence A Wenner, introduce the issue’s genesis and theme: ‘50@50: Assessing the trajectory and challenges of the sociology of sport’. In considering the trajectory of the sociology of sport, the ISSA and the IRSS, they reflect on the early development of the field and the founding of an international association and journal aimed at understanding sport in the social and cultural dynamic; they note early and ongoing challenges concerning the academic seating of the field, its legitimacy and impact, and its engagement with the public sphere and the ‘sociological imagination’. Speaking to the challenges of fashioning a special issue to represent the breadth of 50 years of the sociology of sport, the editors outline how a ‘50@50’ strategy was implemented to bring perspectives from 50 notable scholars and to ensure that a diversity of voices was heard, not only on a range of themes, theories and methods, but from diverse identities and locales. Addressing two overarching challenges – the global dominance of English as the lingua franca of scholarly discourse and the need to advance interdisciplinarity and engagement with scholars beyond the sociology of sport – will be key to broadening dialogue to help ensure the future sustainability and progress of the sociology of sport.Peer reviewedFinal Accepted Versio

    Non-ST-segment elevation acute coronary syndrome: Early versus delayed cardiac catheterization

    Get PDF
    An informed consent conversation regarding early vs. delayed cardiac catheterization for patients with NSTEMI

    On the NP-Hardness of Approximating Ordering Constraint Satisfaction Problems

    Full text link
    We show improved NP-hardness of approximating Ordering Constraint Satisfaction Problems (OCSPs). For the two most well-studied OCSPs, Maximum Acyclic Subgraph and Maximum Betweenness, we prove inapproximability of 14/15+ϵ14/15+\epsilon and 1/2+ϵ1/2+\epsilon. An OCSP is said to be approximation resistant if it is hard to approximate better than taking a uniformly random ordering. We prove that the Maximum Non-Betweenness Problem is approximation resistant and that there are width-mm approximation-resistant OCSPs accepting only a fraction 1/(m/2)!1 / (m/2)! of assignments. These results provide the first examples of approximation-resistant OCSPs subject only to P ≠\neq \NP
    • …