Faunal change in Cretaceous endemic shallow-marine bivalve genera/subgenera of the northeast Pacific

Endemic shallow-marine Cretaceous bivalves in the northeast Pacific region (NEP), extending from southwestern Alaska to the northern part of Baja California Sur, Mexico, are tabulated and discussed in detail for the first time. Twenty-three genera/subgenera are recognized. Their first appearance was in the Valanginian, and their biodiversity continued to be very low during the rest of the Early Cretaceous. The bivalves of the middle Albian Alisitos Formation in northern Baja California are excluded because they did not live in the NEP. The highest number (13) of NEP endemic bivalve genera/subgenera occurred during the Turonian, which was the warmest time of the Cretaceous. At the Turonian/Coniacian boundary, when cooler waters migrated southward, there was a moderate dropoff in endemics that persisted until an origination event near the beginning of the early Maastrichtian, when 11 were present. Five of the 11 were present also during the Turonian, but the others were newcomers. Only three survived the turnover associated with the “Middle Maastrichtian Event” (MME), and none survived the K/Pg boundary mass-extinction event

Inelastic neutron scattering signal from deconfined spinons in a fractionalized antiferromagnet

We calculate the contribution of deconfined spinons to inelastic neutron scattering (INS) in the fractionalized antiferromagnet (AF*), introduced elsewhere. We find that the presence of free spin-1/2 charge-less excitations leads to a continuum INS signal above the Neel gap. This signal is found above and in addition to the usual spin-1 magnon signal, which to lowest order is the same as in the more conventional confined antiferromagnet. We calculate the relative weights of these two signals and find that the spinons contribute to the longitudinal response, where the magnon signal is absent to lowest order. Possible higher-order effects of interactions between magnons and spinons in the AF* phase are also discussed.Comment: 9 page

The Experiences of Christian Paideia among Graduates of Classical Christian Texas High Schools: A Phenomenological Study

The purpose of this study was to describe the essence of the shared lived experiences in a Christian paideia for classical Christian high school graduates at five different Texas schools. Bronfenbrenner’s (1979) Ecological Systems Theory (EST) was the primary theory guiding this study. EST is significant for classical Christian educators because this theory suggests that the behavior and practices of individuals, embodied within a Christian paideia, will profoundly shape the development of students. The central question for this study was how do classical Christian high school graduates describe their lived experiences of Christian paideia? Participants described their lived experiences of Christian paideia in a profound manner. There was a distinct recognition by graduates that their entire being, including heart, soul, and mind, had been purposefully influenced to desire and pursue God’s innate qualities of truth, goodness, and beauty. This study was conducted with a qualitative approach, specifically the transcendental phenomenological method. This qualitative phenomenological approach was a valid design for this study because the research problem being addressed required the understanding of common or shared experiences for a group of classical Christian high school graduates. Snowball sampling was used to select 12 graduates who were derived from those individuals that were purposefully nominated by the headmaster for each of the five respective classical Christian schools. Data collection techniques included individual face-to-face interviews, virtual focus group interviews, and document analysis. Data analysis for this study was completed using Moustakas’s (1994) modification of the Stevick-Colaizzi-Keen method. The results of the study were six major themes that were utilized to answer this study’s central research question and four sub-questions, all of which were designed to describe the essence of the shared lived experiences in a Christian paideia for classical Christian high school graduates

Decisions Squared: A Deeper Look at Student Characteristics, Performance, and Writing Center Usage in a Multilingual Liberal Arts Program in Russia

This article contributes to the ongoing discussion of student characteristics and usage/nonusage patterns in the writing center. Using a sample of 107 economics students from a selective, bilingual liberal arts program in Russia, the author finds statistically significant relationships among GPA, gender, English-language proficiency, and writing center usage. Namely, writing center usage predicts higher GPA and closes two achievement gaps related to gender and English proficiency. These findings complicate the picture presented by Lori Salem (2016), whose research showed gender, low SAT score, and being an English language learner to be strong predictors of writing center usage and produced a lively discussion about whether traditional writing center methods could be failing the students most likely to use the service. The present study suggests that while users may have less systemic social privilege, they also tend to be stronger students. As such, interventions should take care not only to address the needs of the students who actually visit but explore barriers to writing center access for nonvisiting students who are at the highest risk of dropping out

1946-04-23, Everline to Mary

https://digitalcommons.chapman.edu/gvtudor_correspondence_postmortem/1023/thumbnail.jp

Electronic, dynamical, and thermal properties of ultra-incompressible superhard rhenium diboride: A combined first-principles and neutron scattering study

Rhenium diboride is a recently recognized ultra-incompressible superhard material. Here we report the electronic (e), phonon (p), e-p coupling and thermal properties of ReB$_2$ from first-principles density-functional theory (DFT) calculations and neutron scattering measurements. Our calculated elastic constants ($c_{11}$ = 641 GPa, $c_{12}$ = 159 GPa, $c_{13}$ = 128 GPa, $c_{33}$ = 1037 GPa, and $c_{44}$ = 271 GPa), bulk modulus ($B$ $\approx$ 350 GPa) and hardness ($H$ $\approx$ 46 GPa) are in good agreement with the reported experimental data. The calculated phonon density of states (DOS) agrees very well with our neutron vibrational spectroscopy result. Electronic and phonon analysis indicates that the strong covalent B-B and Re-B bonding is the main reason for the super incompressibility and hardness of ReB$_2$. The thermal expansion coefficients, calculated within the quasi-harmonic approximation and measured by neutron powder diffraction, are found to be nearly isotropic in $a$ and $c$ directions and only slightly larger than that of diamond in terms of magnitude. The excellent agreement found between calculations and experimental measurements indicate that first-principles calculations capture the main interactions in this class of superhard materials, and thus can be used to search, predict, and design new materials with desired properties.Comment: submitted to pr

1946-04-23, Everline to Mary

https://digitalcommons.chapman.edu/gvtudor_correspondence_postmortem/1024/thumbnail.jp

Technical Efficiency of the Danish Trawl fleet: Are the Industrial Vessels Better than Others?

Technical efficiency in the Danish trawl fishery in the North Sea is estimated for 1997 and 1998 by a stochastic production frontier model. This model allows noise when the frontier and the technical efficiency is found, which for fisheries is a reasonable assumption. The results show that the production frontier can be modelled by a translog function without time effects and a technical ineffi-ciency function. The type of fishery (industrial or consumption), size of vessel (greater or lesser than 60 GRT) and year give a good explanation for the ineffi-ciency in the fleet. The average technical efficiency is estimated to be 0.82. On average, industrial vessels have a higher technical efficiency than human con-sumption vessels, and smaller vessels have higher technical efficiency than lar-ger vessels. In sum, the analysis reveals that vessel larger than 60 GRT and fishing industrial species are the most efficient.Technical efficiency, stochastic production frontier, Danish trawl fishery

How much does teenage parenthood affect long term outcomes? A systematic review.

Background: The rates of teenage pregnancy in the UK are relatively high. Although early entry to parenthood can be a positive experience, most studies find large adverse effects on long term outcomes for the mother, child and father, in addition to being costly for the NHS. This is why the government launched its Teenage Pregnancy Strategy in 1999. However, there is growing evidence that teenage pregnancy might be mainly an indicator of disadvantage which is the underlying cause of the negative outcomes. Methods: A systematic literature review was undertaken of studies which used a UK dataset to quantify any long term outcomes of a teenage birth upon the mother, father or child. Studies were included if they used appropriate methods to isolate the causal effect of early parenthood. The databases searched included Medline, Cochrane, EconLit and Web of Science. Results: Six studies were identified by the review; five studies considered the mother’s socioeconomic outcomes, one study reported the child’s outcomes, and no studies met the inclusion criteria for the father’s outcomes. The studies suggested that early motherhood accounts for relatively few of the negative long term socioeconomic outcomes and it is predominantly an indicator of a disadvantaged family background. Conclusion: Limited evidence is available to understand the long term outcomes associated with teenage birth within the UK for the mother, father and child. Current econometric studies suggest that effective interventions to prevent teenage pregnancies will not eradicate the poorer long term socioeconomic outcomes often associated with early motherhood. Thus policy should focus on reducing initial disadvantage in addition to preventing teenage pregnancy. Additional econometric analyses around the mothers’, fathers’ and children’s long term socioeconomic and health-related outcomes would be valuable