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Adaptive strong-field control of vibrational population in NO2+
Get PDFAn adaptive closed-loop system employing coincidence time-of-flight feedback is used to determine the optimal pulse shapes for manipulating the branching ratio of NO dications following double ionization by an intense laser pulse. Selection between the long-lived NO2+ and the dissociative N+ + O+ final states requires control of the vibrational population distribution in the transient NO2+. The ability to both suppress and enhance NO2+ relative to N+ + O+ is observed, with the effectiveness of shaped pulses surpassing near Fourier transform-limited pulses by about an order of magnitude in each direction, depending on the pulse energy. The control is subsequently investigated using velocity map imaging, identifying plausible dissociation pathways leading to N+ + O+. Combining the information about the N+ + O+ dissociation with a well-defined control objective supports the conclusion that the primary control mechanism involves selectively populating long-lived NO2+ vibrational states
Pulse-duration dependence of the double-to-single ionization ratio of Ne by intense 780-nm and 800-nm laser fields: Comparison of simulations with experiments
Get PDFAccurate ab initio calculations of the ratio of double-to-single ionization of Ne atoms in strong laser fields are difficult due to the many-electron nature of the target. Here, with accurate total cross sections carefully evaluated by using the state-of-the-art many-electron R-matrix theory for both electron-impact ionization and electron-impact excitation of Ne+, we simulate the total double-ionization yields of Ne2+ in strong laser fields at 780 and 800 nm for pulse durations in the range from 7.5 to 200 fs based on the improved quantitative rescattering model. The corresponding single-ionization yields of Ne+ are calculated within the nonadiabatic tunneling model of Perelomov, Popov, and Terent'ev. The ratio of double-to-single ionization of Ne is then obtained from the calculated double- and single-ionization yields. By normalizing the ratio to the one calculated from solving the time-dependent Schrödinger equation for a short few-cycle pulse, we make quantitative comparisons of our results with experimental data to show that our model predicts the experimental findings very well. Finally, we analyze the pulse-duration dependence of the double-to-single ionization ratio
Testing Luminescence Dating Methods for Small Samples from Very Young Fluvial Deposits
Get PDFThe impetus behind this study is to understand the sedimentological dynamics of very young fluvial systems in the Amazon River catchment and relate these to land use change and modern analogue studies of tidal rhythmites in the geologic record. Initial quartz optically stimulated luminescence (OSL) dating feasibility studies have concentrated on spit and bar deposits in the Rio Tapajós. Many of these features have an appearance of freshly deposited pristine sand, and these observations and information from anecdotal evidence and LandSat imagery suggest an apparent decadal stability. The characteristics of OSL from small (~5 cm) sub-samples from ~65 cm by ~2 cm diameter vertical cores are quite remarkable. Signals from medium-sized aliquots (5 mm diameter) exhibit very high specific luminescence sensitivity, have excellent dose recovery and recycling, essentially independent of preheat, and show minimal heat transfer even at the highest preheats. These characteristics enable measurement of very small signals with reasonable precision and, using modified single-aliquot regenerative-dose (SAR) approaches, equivalent doses as low as ~4 mGy can be obtained. Significant recuperation is observed for samples from two of the study sites and, in these instances, either the acceptance threshold was increased or growth curves were forced through the origin; recuperation is considered most likely to be a measurement artefact given the very small size of natural signals. Dose rates calculated from combined inductively coupled plasma mass spectrometry/inductively coupled plasma optical emission spectrometry (ICP-MS/ICP-OES) and high-resolution gamma spectrometry range from ~0.3 to 0.5 mGya−1 , and OSL ages for features so far investigated range from 13 to 34 years to several 100 years. Sampled sands are rich in quartz and yields of 212–250 µm or 250–310 µm grains indicate high-resolution sampling at 1–2 cm intervals is possible. Despite the use of medium-sized aliquots to ensure the recovery of very dim natural OSL signals, these results demonstrate the potential of OSL for studying very young active fluvial processes in these settings
Vibrant Communitites with a Postive Future Kansas PRIDE Impact 2018 - 2019
No full textSummary of the 2018-2019 actiivities of the Kansas PRIDE program and affiliated communities
UNN34A_2019_01
No full textThis informal report to the Kansas Legislature summarizes the impact of Kansas State's College of Agriculture educational programs in 2019
The influence of social media on Saudi graduate students: an explanatory case study of six Saudi graduate students studying in American universities
Get PDFDoctor of PhilosophyCurriculum and Instruction ProgramsKay Ann TaylorThe purpose of this qualitative multiple participant case study was to identify the influence of social media on Saudi graduate students who are active social media users. Social media have been influencing Saudi students differently than those in other socio-cultural contexts due to the uniqueness of the Kingdom of Saudi Arabia (KSA) in terms of cultural, political, economic, and social life. This study contributes to educational technology broadly and understanding the experiences of Saudi graduate students who are active social media users specifically. This study sought to illuminate and clarify understanding of the influence of social media use on graduate students in the KSA. This study investigated the influence of social media on Saudi graduate students through the experience of six Saudi graduate students who have 200K or more followers/subscribers on YouTube, Twitter, Instagram, or Snapchat.
Vygotsky-based social constructivism was used to analyze and interpret the findings of the research in an effort to understand and make sense of the impact of social media on education through the participants’ experiences as graduate students and active social media users. The significant findings of this research support social constructivism, in that learning occur through social interaction with the More Knowledgeable Other (MKO) in the Zone of Proximal Development (ZPD). The findings of the study included three emerging themes: (1) social media experience, (2) social media influence, and (3) changes brought by social media. Two categories emerged from the data under the first theme. The categories are (a) planned versus unplanned fame, and (b) social media preferred sites, activities and topics. Three categories and two sub-categories emerged from the second theme: (a) educational influence, which has two sub-categories —(i) formal teaching and learning (ii) informal learning —; (b) financial influence; and (c) gender issues in social media. The results contribute to the limited qualitative research on Saudi graduate students and social media and to the overall social constructivism research in the KSA higher education
Using Apps to Enhance Students' Learning of English Vocabulary
Get PDFNowadays, education in the Kingdom of Saudi Arabia is entering a new phase (Saudi Vision 2030), which focuses on quality of education, ensuring that students are being prepared to deal with future challenges such as cultural diversity, economic changes, and globalization. Because of English becoming more important under the trend of globalization and internationalization, it is considered to be one of the most important foreign languages in Saudi Arabia. Teaching and learning a foreign language through technology has become a new trend in foreign language education all over the world (Liu, 2009). Hence, technology integration in our classrooms has become an important aspect of successful teaching. I find that many students are demotivated to learn English language because they do not realize the advantage of learning it. Therefore, EFL students in Saudi Arabia often struggle with literacy and vocabulary retention, which also affects their grammar learning and reading comprehension. As a result, I presume that this project will be a good opportunity to take advantage of students' interests in technological tools, such as cell phones apps, in order to help increase students' vocabulary and trigger their desire to learn the language. However, I intend to implement this project with the seventh-grade students at Al-Ghuzayat Middle School in Al-Jamoum, Makkah, Saudi Arabia, by using two apps: Duolingo and Kahoot in a period of 12 weeks so that I can evaluate the effects of learning vocabulary through these two apps by taking a pretest, a posttest, and a survey at the end
Are There Price Asymmetries in the U.S. Beef Market?
Get PDFWe examine price transmissions among farm, wholesale and retail U.S. beef markets using two types of retail price data, one collected by the Bureau of Labor Statistics (BLS), and the other one collected at the point of sale using electronic scanners. Using a test based on the simulation of nonlinear impulse response functions, we find no evidence of vertical asymmetric price transmissions in models estimated using scanner data. However, prices adjust asymmetrically in models estimated using BLS data. Because scanner prices are more reflective of actual consumer purchases, the U.S. beef market is not as inefficient as previous studies suggest
Effects of corn gluten feed substituting soy bean meal on performance of Boer goats
No full textWith this study comes a hope to build information for the growing goat industry, and to establish better formulation combinations for producers. This study was concerned with the impact of substituting corn gluten feed (CGF) or corn dried distillers grains with solubles (DDGS) for soybean meal (SBM) in the growth performance of crossbred Boer goats. Seventy-five Boer type goats (26.9±0.2kg, approximately 70 days of age) were used in a completely randomized design with three goats per pens, with five pens per treatment, with pens being the experimental unit. Goats were fed for 35 d, along with feeders and goats being weighed weekly for effects on ADG, ADFI, G:F. The five treatments varied in ingredients used as the protein source but were isocaloric, isonitrogenous. Treatments were, 1) soybean meal; 2) 100% DDGS/0% CGF; 3) 66% DDGS/33% CGF; 4) 33% DDGS/66% CGF; 5) 0% DDGS/100% CGF. The GLIMMIX procedure of SAS (v. 9.4, Cary, NC) was used to analyze data with an alpha value of 0.05. No impact of diet was detected on BW, ADG, ADFI, G:F (P < 0.05). It was discovered that feed costs between SBM or corn co-products as the protein source varied by $0.04/kg. This led to goats being fed corn co-products having lower (P = 0.0008) feed costs/goat during the 35-d experiment. However, feed cost per kg of gain did not differ (P = 0.941) among treatments. In conclusion, no difference was determined other than costs between the SBM control and CGF/ DDGS substitution. Therefore, these results suggest CGF or DDGS can completely substitute SBM in the diet of Boer type goats in a cost-effective manner, with no detected impacted on growth performance