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

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

Radiogenic power and geoneutrino luminosity of the Earth and other terrestrial bodies through time

We report the Earth's rate of radiogenic heat production and (anti)neutrino luminosity from geologically relevant short-lived radionuclides (SLR) and long-lived radionuclides (LLR) using decay constants from the geological community, updated nuclear physics parameters, and calculations of the $\beta$ spectra. We track the time evolution of the radiogenic power and luminosity of the Earth over the last 4.57 billion years, assuming an absolute abundance for the refractory elements in the silicate Earth and key volatile/refractory element ratios (e.g., Fe/Al, K/U, and Rb/Sr) to set the abundance levels for the moderately volatile elements. The relevant decays for the present-day heat production in the Earth ($19.9\pm3.0$ TW) are from $^{40}$K, $^{87}$Rb, $^{147}$Sm, $^{232}$Th, $^{235}$U, and $^{238}$U. Given element concentrations in kg-element/kg-rock and density $\rho$ in kg/m$^3$, a simplified equation to calculate the present day heat production in a rock is: $$h \, [\mu \text{W m}^{-3}] = \rho \left( 3.387 \times 10^{-3}\,\text{K} + 0.01139 \,\text{Rb} + 0.04595\,\text{Sm} + 26.18\,\text{Th} + 98.29\,\text{U} \right)$$ The radiogenic heating rate of Earth-like material at Solar System formation was some 10$^3$ to 10$^4$ times greater than present-day values, largely due to decay of $^{26}$Al in the silicate fraction, which was the dominant radiogenic heat source for the first $\sim10$ Ma. Assuming instantaneous Earth formation, the upper bound on radiogenic energy supplied by the most powerful short-lived radionuclide $^{26}$Al ($t_{1/2}$ = 0.7 Ma) is 5.5$\;\times\;$10$^{31}$ J, which is comparable (within a factor of a few) to the planet's gravitational binding energy.Comment: 28 pages, 6 figures, 5 table

Combined analysis of KamLAND and Borexino neutrino signals from Th and U decays in the Earth's interior

The KamLAND and Borexino experiments have detected electron antineutrinos produced in the decay chains of natural thorium and uranium (Th and U geoneutrinos). We analyze the energy spectra of current geoneutrino data in combination with solar and long-baseline reactor neutrino data, with marginalized three-neutrino oscillation parameters. We consider the case with unconstrained Th and U event rates in KamLAND and Borexino, as well as cases with fewer degrees of freedom, as obtained by successively assuming for both experiments a common Th/U ratio, a common scaling of Th+U event rates, and a chondritic Th/U value. In combination, KamLAND and Borexino can reject the null hypothesis (no geoneutrino signal) at 5 sigma. Interesting bounds or indications emerge on the Th+U geoneutrino rates and on the Th/U ratio, in broad agreement with typical Earth model expectations. Conversely, the results disfavor the hypothesis of a georeactor in the Earth's core, if its power exceeds a few TW. The interplay of KamLAND and Borexino geoneutrino data is highlighted.Comment: 12 pages, including 6 figure

Entrepreneurial Literary Theory: A Debate on Research and the Future of Academia

Across the world at present, researchers and teachers are being exhorted to become entrepreneurial. Universities are being restructured accordingly. The debate presented in this book considers what that involves and portends for academia. Literary studies are often regarded as the most resistant to – unfit for – entrepreneurial purposes. Literary research is therefore taken as a baseline for this debate. The uneasy place of literary research within profit-driven academia is revealing of the prevailing conditions for scholarship in all areas. Questions that are raised and discussed here include: What does doing research for the public good mean? What is the relationship between profits and benefits from research? What are applied and basic research? Are concepts of academic freedom and disinterestedness meaningful? What is the relationship between corporate and academic research? Are skills and knowledge different? Can pursuits like close reading and text interpretation be made profitable? What is literary value and how can it be measured? Can the literary system be modelled to profitable ends? Can university teaching be automatized? What are the differences between a standard publication agreement and a scholarly publication agreement? How can digital and open-access academic publication be made profitable? Does the academic monograph have a future? What sorts of knowledge and skills inform entrepreneurial leadership

ISN Forefronts Symposium 2015: Maintaining Balance Under Pressure—Hypertension and the Proximal Tubule

Renal control of effective circulating volume (ECV) is key for circulatory performance. When renal sodium excretion is inadequate, blood pressure rises and serves as a homeostatic signal to drive natriuresis to re-establish ECV. Recognizing that hypertension involves both renal and vascular dysfunction, this report concerns proximal tubule sodium hydrogen exchanger 3 (NHE3) regulation during acute and chronic hypertension. NHE3 is distributed in tall microvilli (MV) in the proximal tubule, where it reabsorbs a significant fraction of the filtered sodium. NHE3 redistributes, in the plane of the MV membrane, between the MV body, where NHE3 is active, and the MV base, where NHE3 is less active. A high-salt diet and acute hypertension both retract NHE3 to the base and reduce proximal tubule sodium reabsorption independent of a change in abundance. The renin angiotensin system provokes NHE3 redistribution independent of blood pressure: The angiotensin-converting enzyme (ACE) inhibitor captopril redistributes NHE3 to the base and subsequent angiotensin II (AngII) infusion returns NHE3 to the body of the MV and restores reabsorption. Chronic AngII infusion presents simultaneous AngII stimulation and hypertension; that is, NHE3 remains in the body of the MV, due to the high local AngII level and inflammation, and exhibits a compensatory decrease in abundance driven by the hypertension. Genetically modified mice with blunted hypertensive responses to chronic AngII infusion (due to lack of the proximal tubule AngII receptors interleukin-17A or interferon-γ expression) exhibit reduced local AngII accumulation and inflammation and larger decreases in NHE3 abundance, which improves the pressure natriuresis response and reduces the need for elevated blood pressure to facilitate circulating volume balance

Performing Critical Consciousness in Teaching: Entanglements of Knowing, Feeling and Relating

At a time when education reform is guided by neoliberalism, accountability and standardization have reshaped teaching as highly technocratic and threatened the democratic possibilities of public education. Even so, many teacher education programs have taken up the call to prepare teachers to teach for social justice, whether framed as multicultural education, critical literacy, or critical pedagogy. A construct that ties these pedagogical approaches together is critical consciousness, with the aim of some teacher education efforts to evoke critical consciousness among preservice teachers. This study focuses on exploring how nine educators from elementary grades to higher education experience and enact critical consciousness in their own work of teaching and leading schools. Using ethnographic methods for data collection, I spent a year visiting the classrooms and schools of elementary teachers, high school teachers, an art teacher, two principals and two teacher educators to learn how they thought about criticality and taught critically. I engaged with and analyzed the data through reading and writing as methods of analysis and in dialogue with theory to create a layered text (Ellingson, 2011). In the teacher education literature critical consciousness is mainly situated as a cognitive experience that individuals have or acquire. This research expands the construct of critical consciousness from a modernist view of criticality to a poststructural exploration of the production of critical consciousness. It challenges notions of critical consciousness as an individual attribute that is attained and which then functions as the source of criticality. Instead it reconstructs critical consciousness as a performed social relation and embodied experience that re/produces variations of criticality from moment to moment and across contexts. I highlight critical consciousness as intersubjective and an entanglement among rational knowing, feeling, and doing as a result of engagement with others. This study has implications for teacher education including the need to think differently about relationship-building, understanding education as political, developing critical literacy through multiple ways of knowing, and “reading” our teaching and our lives

Alien Registration- Mcdonough, Mary A. (South Portland, Cumberland County)

https://digitalmaine.com/alien_docs/20133/thumbnail.jp

Alien Registration- Mcdonough, Mary A. (South Portland, Cumberland County)

https://digitalmaine.com/alien_docs/20133/thumbnail.jp