On the determination of anti-neutrino spectra from nuclear reactors

In this paper we study the effect of, well-known, higher order corrections to the allowed beta decay spectrum on the determination of anti-neutrino spectra resulting from the decays of fission fragments. In particular, we try to estimate the associated theory errors and find that induced currents like weak magnetism may ultimately limit our ability to improve the current accuracy and under certain circumstance could even largely increase the theoretical errors. We also perform a critical evaluation of the errors associated with our method to extract the anti-neutrino spectrum using synthetic beta spectra. It turns out, that a fit using only virtual beta branches with a judicious choice of the effective nuclear charge provides results with a minimal bias. We apply this method to actual data for U235, Pu239 and Pu241 and confirm, within errors, recent results, which indicate a net 3% upward shift in energy averaged anti-neutrino fluxes. However, we also find significant shape differences which can in principle be tested by high statistics anti-neutrino data samples.Comment: 20 pages, 5 figures, 9 tables, added references, version accepted for publication in Phys. Rev. C. Corrected errors in tab. 1 and eqs. 18 and 19. Results and conclusion unchange

Beach impact study, Padre Island National Seashore

Prepared for Office of Natural Science, Southwest Region, National Park Service, under contract CX70005044830 April 1976Vegetative differences between heavily and very lightly trafficked beaches show that more beach traffic correlates with quantitative decreases in variety and density of plants and with declines of grasses relative to forbs. The vegetated portions of all beaches continue to grow in volume. However, this is at the expense of the more seaward (more trafficked) parts of the beaches and has lead to overall loss of total beach volume except where vehicular traffic is prohibited. The very lightly trafficked beach is the only study site wherein the entire beach to mean sea level has grown. The effect of these trends on resistance to storm surge erosion remains to be tested.Marine Scienc

Playing “Sherlock Holmes”: Enhancing students’ understanding of prejudice and stereotyping

A very simple, innovative classroom exercise designed to heighten students\u27 understanding of stereotyping and prejudice is described. Students\u27 evaluation of the exercise was very positive. Students reported greater awareness and understanding of their own and others’ stereotypes and prejudice and of the negative effects of prejudice, with females more than males reporting enhanced awareness of others’ stereotyping. Students also rated the exercise as very enjoyable. There was a trend among Non-White more than White students to report that the exercise helped show them how to reduce stereotypes and more Non-White than White students offered solutions for reducing prejudice that involved actively reaching out and interacting with others different from themselves. Additional suggestions for instructors are discussed

Algal culture studies for CELSS

Microalgae are well-suited as a component of a Closed Environmental Life Support System (CELSS), since they can couple the closely related functions of food production and atmospheric regeneration. The objective was to provide a basis for predicting the response of CELSS algal cultures, and thus the food supply and air regeneration system, to changes in the culture parameters. Scenedesmus growth was measured as a function of light intensity, and the spectral dependence of light absorption by the algae as well as algal respiration in the light were determined as a function of cell concentration. These results were used to test and confirm a mathematical model that describes the productivity of an algal culture in terms of the competing processes of photosynthesis and respiration. The relationship of algal productivity to cell concentration was determined at different carbon dioxide concentrations, temperatures, and light intensities. The maximum productivity achieved by an air-grown culture was found to be within 10% of the computed maximum productivity, indicating that CO2 was very efficiently removed from the gas stream by the algal culture. Measurements of biomass productivity as a function of cell concentration at different light intensities indicated that both the productivity and efficiency of light utilization were greater at higher light intensities

Spatially uniform calibration of a liquid xenon detector at low energies using 83m-Kr

A difficult task with many particle detectors focusing on interactions below ~100 keV is to perform a calibration in the appropriate energy range that adequately probes all regions of the detector. Because detector response can vary greatly in various locations within the device, a spatially uniform calibration is important. We present a new method for calibration of liquid xenon (LXe) detectors, using the short-lived 83m-Kr. This source has transitions at 9.4 and 32.1 keV, and as a noble gas like Xe, it disperses uniformly in all regions of the detector. Even for low source activities, the existence of the two transitions provides a method of identifying the decays that is free of background. We find that at decreasing energies, the LXe light yield increases, while the amount of electric field quenching is diminished. Additionally, we show that if any long-lived radioactive backgrounds are introduced by this method, they will present less than 67E-6 events/kg/day in the next generation of LXe dark matter direct detection searchesComment: 9 pages, 9 figures. Accepted to Review of Scientific Instrument

Deep into the structure of the first galaxies: SERRA views

We study the formation and evolution of a sample of Lyman Break Galaxies in the Epoch of Reionization by using high-resolution ($\sim 10 \,{\rm pc}$), cosmological zoom-in simulations part of the SERRA suite. In SERRA, we follow the interstellar medium (ISM) thermo-chemical non-equilibrium evolution, and perform on-the-fly radiative transfer of the interstellar radiation field (ISRF). The simulation outputs are post-processed to compute the emission of far infrared lines ([CII], [NII], and [OIII]). At $z=8$, the most massive galaxy, `Freesia', has an age $t_\star \simeq 409\,{\rm Myr}$, stellar mass $M_{\star} \simeq 4.2\times 10^9 {\rm M}_{\odot}$, and a star formation rate ${\rm SFR} \simeq 11.5\,{\rm M}_{\odot}{\rm yr}^{-1}$, due to a recent burst. Freesia has two stellar components (A and B) separated by $\simeq 2.5\, {\rm kpc}$; other 11 galaxies are found within $56.9 \pm 21.6 \, {\rm kpc}$. The mean ISRF in the Habing band is $G = 7.9\, G_0$ and is spatially uniform; in contrast, the ionisation parameter is $U = 2^{+20}_{-2} \times 10^{-3}$, and has a patchy distribution peaked at the location of star-forming sites. The resulting ionising escape fraction from Freesia is $f_{\rm esc}\simeq 2\%$. While [CII] emission is extended (radius 1.54 kpc), [OIII] is concentrated in Freesia-A (0.85 kpc), where the ratio $\Sigma_{\rm [OIII]}/\Sigma_{\rm [CII]} \simeq 10$. As many high-$z$ galaxies, Freesia lies below the local [CII]-SFR relation. We show that this is the general consequence of a starburst phase (pushing the galaxy above the Kennicutt-Schmidt relation) which disrupts/photodissociates the emitting molecular clouds around star-forming sites. Metallicity has a sub-dominant impact on the amplitude of [CII]-SFR deviations.Comment: 22 pages, 14 figures, accepted by MNRA

Arabidopsis peroxisome proteomics

The analytical depth of investigation of the peroxisomal proteome of the model plant Arabidopsis thaliana has not yet reached that of other major cellular organelles such as chloroplasts or mitochondria. This is primarily due to the difficulties associated with isolating and obtaining purified samples of peroxisomes from Arabidopsis. So far only a handful of research groups have been successful in obtaining such fractions. To make things worse, enriched peroxisome fractions frequently suffer from significant organellar contamination, lowering confidence in localization assignment of the identified proteins. As with other cellular compartments, identification of peroxisomal proteins forms the basis for investigations of the dynamics of the peroxisomal proteome. It is therefore not surprising that, in terms of functional analyses by proteomic means, peroxisomes are lagging considerably behind chloroplasts or mitochondria. Alternative strategies are needed to overcome the obstacle of hard-to-obtain organellar fractions. This will help to close the knowledge gap between peroxisomes and other organelles and provide a full picture of the physiological pathways shared between organelles. In this review, we briefly summarize the status quo and discuss some of the methodological alternatives to classic organelle proteomic approaches.Australian ResearchCouncil/CE0561495DF

Neutrino and antineutrino charge-exchange reactions on 12C

We extend the formalism of weak interaction processes, obtaining new expressions for the transition rates, which greatly facilitate numerical calculations, both for neutrino-nucleus reactions and muon capture. Explicit violation of CVC hypothesis by the Coulomb field, as well as development of a sum rule approach for the inclusive cross sections have been worked out. We have done a thorough study of exclusive (ground state) properties of $^{12}$B and $^{12}$N within the projected quasiparticle random phase approximation (PQRPA). Good agreement with experimental data achieved in this way put in evidence the limitations of standard RPA and the QRPA models, which come from the inability of the RPA in opening the $p_{3/2}$ shell, and from the non-conservation of the number of particles in the QRPA. The inclusive neutrino/antineutrino ($\nu/\tilde{\nu}$) reactions $^{12}$C($\nu,e^-)^{12}$N and $^{12}$C($\tilde{\nu},e^+)^{12}$B are calculated within both the PQRPA, and the relativistic QRPA (RQRPA). It is found that the magnitudes of the resulting cross-sections: i) are close to the sum-rule limit at low energy, but significantly smaller than this limit at high energies both for $\nu$ and $\tilde{\nu}$, ii) they steadily increase when the size of the configuration space is augmented, and particulary for $\nu/\tilde{\nu}$ energies $> 200$ MeV, and iii) converge for sufficiently large configuration space and final state spin. The quasi-elastic $^{12}$C($\nu,\mu^-)^{12}$N cross section recently measured in the MiniBooNE experiment is briefly discussed. We study the decomposition of the inclusive cross-section based on the degree of forbiddenness of different multipoles. A few words are dedicated to the $\nu/\tilde{\nu}$-$^{12}$C charge-exchange reactions related with astrophysical applications.Comment: 21 pages, 13 figures, 1 table, submitted to Physical Review

Effect of assumptions by pre-service teachers concerning family life, extracurricular involvement and socioeconomic status [abstract]

Abstract only availableThe state of Missouri wants to produce highly qualified educators in order to facilitate high performing students; because of this it is vital that pre-service teachers alter their expectation in order to maintain high expectations for all students thus lessoning the achievement gap. For over twenty years researchers have demonstrated that teacher expectations have impacted student's academic performance. Tom Good states, “Teachers' high expectations of their students contributes to students achieving at or near their potential, while students receiving low expectations will not gain as much as they could have if taught differently” (1987). As pre-service teachers (students in the teacher development program taking 2000 level courses) develop as educators at the University of Missouri the knowledge of what impacts their expectations needs to be understood in order to adjust them to best meet their student's academic needs. These teachers are being placed in America's classroom and have a direct impact on student's educational performance. Lower student performance resulting from low teacher expectations may result in low test scores for students leading to lowered funding and decreased value in the district. Within this research we will be examining what formulates pre-service teacher's expectations of their students. Our research is crucial to determining how to better educate future teachers in order to establish teacher's high expectations and higher achievement from their students. In order to determine these factors we poled 368 students in an entry level teacher development course at the University of Missouri. In the past the expectations of in-service teacher's has been studied in correlation with student achievement to determine the effect upon students' performance. Past research has shown race to be a large factor in teacher expectation. For example generally African American students are thought to perform poorly, while Asian students are expected to perform highly. We will analyze University of Missouri pre-service teacher's survey responses in order to identify patterns within their reasoning for the expectation given. Surveys included mixed race variable and factors that one might infer would impact teacher expectations, such as family life, extracurricular involvement, and socio economic status of the different scenarios represented. Surveys included a control scenario with a race, gender, and SES variable

Numerical and experimental investigations on an extrusion process for a newly developed ultra-high-carbon lightweight steel for the automotive industry

In this study the material flow of a newly developed ultra-high-carbon lightweight steel (uhc-steel) with a high amount of aluminum was investigated in an extrusion process. Cylinder compression tests were performed for material characterization and frictional behaviour was determined by using ring compression tests. Numerical simulations were carried to determine the optimal die geometry as well as to calculate the process loads and dominated stresses in the die occurring during the process. Based on the numerical results, an extrusion process was designed and implemented. Experiments showed that the uhc-steel can be formed by extrusion however it is associated with a high wear rate.BMB