Research Notes: Histology of the Embryo Sac of Male Sterile ms1ms1 Soybeans

The fact that ms1ms1 plants in maturity ranges I to V were producing haploids, triploids, and even higher ploidy levels along with the predominant normal diploids, indicated the female gametophyte was at least occasionally functioning abnormally. Histological sections of 92 male sterile pistils from plants about Groups III and IV, indicated only about 28% of the ovules had a normal embryo sac, by our interpretation. The remainder most commonly had extra nuclei in the regions of the secondary nucleus (endosperm mother cell) and/or the egg apparatus

Research Notes: Progress in Obtaining Soybean Haploids 2n=20

Male sterility gene ms 1 from North Carolina was transferred to maturity groups I, II, and III over the last few years to facilitate the use in Wisconsin of the twinning and haploidy phenomena associated with ms1ms1 plants. In 1975 we had an extended fall growing season and seed was obtained from several hundred male sterile ms 1ms1 plants, representing maturity groups I, II, III, IV, and V. Honey bees were used as pollinators

The origin of the red luminescence in Mg-doped GaN

Optically-detected magnetic resonance (ODMR) and positron annihilation spectroscopy (PAS) experiments have been employed to study magnesium-doped GaN layers grown by metal-organic vapor phase epitaxy. As the Mg doping level is changed, the combined experiments reveal a strong correlation between the vacancy concentrations and the intensity of the red photoluminescence band at 1.8 eV. The analysis provides strong evidence that the emission is due to recombination in which electrons both from effective mass donors and from deeper donors recombine with deep centers, the deep centers being vacancy-related defects.Comment: 4 pages, 3 figure

Amplification and generation of ultra-intense twisted laser pulses via stimulated Raman scattering

Twisted Laguerre-Gaussian lasers, with orbital angular momentum and characterised by doughnut shaped intensity profiles, provide a transformative set of tools and research directions in a growing range of fields and applications, from super-resolution microcopy and ultra-fast optical communications to quantum computing and astrophysics. The impact of twisted light is widening as recent numerical calculations provided solutions to long-standing challenges in plasma-based acceleration by allowing for high gradient positron acceleration. The production of ultrahigh intensity twisted laser pulses could then also have a broad influence on relativistic laser-matter interactions. Here we show theoretically and with ab-initio three-dimensional particle-in-cell simulations, that stimulated Raman backscattering can generate and amplify twisted lasers to Petawatt intensities in plasmas. This work may open new research directions in non-linear optics and high energy density science, compact plasma based accelerators and light sources.Comment: 18 pages, 4 figures, 1 tabl

Student Misbehaviors, Instructor Responses, And Connected Classroom Climate: Implications for the Basic Course

The concept of connected classroom climate focuses on student-to-student communication behaviors that are paramount in creating the climate of a class, especially in the basic course. While previous studies have focused on the positive and cooperative behaviors of students and instructors that may contribute to perceptions of classroom connectedness, the role that incivilities may play in detracting from or undermining a connected classroom climate has not been investigated. This study examines perceptions of a connected classroom climate and its relationships to student misbehaviors and instructor responses. A total of 542 university students enrolled in 30 sections of the basic public speaking course completed the Connected Classroom Climate Inventory (CCCI) and scales measuring student misbehaviors and teacher responses to student misbehaviors. Results showed that student perceptions of a connected classroom climate were inversely related to both inconsiderate and harassing student misbehaviors. The results also revealed a possible relationship between classroom connectedness and the manner in which instructors respond to students when they misbehave. These findings suggest that basic course instructors need to consider how to reduce student inconsideration and harassment misbehaviors in their classes, and how to positively respond to these behaviors when they do occur so that classroom connectedness is not diminished

Research Notes: University of Wisconsin

Tissue culture methods may benefit soybean breeders if whole plants can be differentiated from aneuploid, mutated, fused, or haploid cells. However, in order to realize this potential, it must be possible to derive plantlets from previously undifferentiated tissues - and ultimately from masses of callus cells. This report summarizes the information we obtained concerning adventitious budding from soybean tissues (Kimball and Bingham, 1973), early stages of embryo formation within masses of callus cells, and actual differentiation of plantlets from callus tissue

Gibrat's law for cities: uniformly most powerful unbiased test of the Pareto against the lognormal

We address the general problem of testing a power law distribution versus a log-normal distribution in statistical data. This general problem is illustrated on the distribution of the 2000 US census of city sizes. We provide definitive results to close the debate between Eeckhout (2004, 2009) and Levy (2009) on the validity of Zipf's law, which is the special Pareto law with tail exponent 1, to describe the tail of the distribution of U.S. city sizes. Because the origin of the disagreement between Eeckhout and Levy stems from the limited power of their tests, we perform the {\em uniformly most powerful unbiased test} for the null hypothesis of the Pareto distribution against the lognormal. The $p$-value and Hill's estimator as a function of city size lower threshold confirm indubitably that the size distribution of the 1000 largest cities or so, which include more than half of the total U.S. population, is Pareto, but we rule out that the tail exponent, estimated to be $1.4 \pm 0.1$, is equal to 1. For larger ranks, the $p$-value becomes very small and Hill's estimator decays systematically with decreasing ranks, qualifying the lognormal distribution as the better model for the set of smaller cities. These two results reconcile the opposite views of Eeckhout (2004, 2009) and Levy (2009). We explain how Gibrat's law of proportional growth underpins both the Pareto and lognormal distributions and stress the key ingredient at the origin of their difference in standard stochastic growth models of cities \cite{Gabaix99,Eeckhout2004}.Comment: 7 pages + 2 figure

Connected Classroom Climate and Communication in the Basic Course: Associations with Learning

Most research on the association between classroom climate and student learning has emphasized the instructor’s role in creating a positive learning environment. However, the role students play in fostering a classroom climate that promotes learning has received less attention, particularly in the basic course. This study examined the relationship between perceptions of a connected classroom climate and students’ cognitive and affective learning involving 437 freshman and sophomore university students enrolled in the basic public speaking course. Students completed the Connected Classroom Climate Inventory (CCCI) and scales measuring affective and cognitive learning. Results showed significant relationships between student perceptions of connected classroom climate and cognitive learning, affective learning, and affective behavioral intent