High-speed measurement of rotational anisotropy nonlinear optical harmonic generation using position sensitive detection

We present a method of performing high-speed rotational anisotropy nonlinear optical harmonic generation experiments at rotational frequencies of several hertz by projecting the harmonic light reflected at different angles from a sample onto a stationary position sensitive detector. The high rotational speed of the technique, $10^3$ to $10^4$ times larger than existing methods, permits precise measurements of the crystallographic and electronic symmetries of samples by averaging over low frequency laser power, beam pointing, and pulse width fluctuations. We demonstrate the sensitivity of our technique by resolving the bulk four-fold rotational symmetry of GaAs about its [001] axis using second harmonic generation

The onion industry in Pleasant Valley, Iowa

The Pleasant Valley onion district in Scott county, Iowa, presents a striking example of crop specialization and intensive culture in contrast to the typical corn belt farming which prevails in this state. Approximately 500 acres are devoted exclusively to onions on a continuous crop basis, and much of the land has been devoted to this particular crop for decades. This is one of the oldest agricultural regions of the state. In the following pages is presented a summary of a farm survey* of the onion industry of this region, including a study of the cultural practices, the problems of disease and insect control, cost of production, marketing, tenure and the seasonal distribution of labor

Enhanced heat capacity and a new temperature instability in superfluid He-4 in the presence of a constant heat flux near T-lambda

We present the first experimental evidence that the heat capacity of superfluid 4He, at temperatures very close to the lambda point Tλ, is enhanced by a constant heat flux Q. The heat capacity at constant Q, CQ, is predicted to diverge at a temperature Tc(Q)<Tλ at which superflow becomes unstable. In agreement with previous measurements, we find that dissipation enters our cell at a temperature, TDAS(Q), below the theoretical value, Tc(Q). We argue that TDAS(Q) can be accounted for by a temperature instability at the cell wall, and is therefore distinct from Tc(Q). The excess heat capacity we measure has the predicted scaling behavior as a function of T and Q, but it is much larger than predicted by current theory

Tetrahedral Symmetry in Ground- and Low-Lying States of Exotic A ~ 110 Nuclei

Recent theoretical calculations predict a possible existence of nuclei with tetrahedral symmetry: more precisely, the mean-field hamiltonians of such nuclei are symmetric with respect to double point-group Td. In this paper, we focus on the neutron-rich Zirconium isotopes as an example and present realistic mean-field calculations which predict tetrahedral ground-state configurations in 108,110Zr and low-lying excited states of tetrahedral symmetry in a number of N > 66 isotopes. The motivations for focusing on these nuclei, as well as a discussion of the possible experimental signatures of tetrahedral symmetry are also presented.Comment: Accepted in Phys. Rev. C - Rapid Communication

Nuclear Tetrahedral Symmetry: Possibly Present Throughout the Periodic Table

More than half a century after the fundamental, spherical shell structure in nuclei has been established, theoretical predictions indicate that the shell-gaps comparable or even stronger than those at spherical shapes may exist. Group-theoretical analysis supported by realistic mean-field calculations indicate that the corresponding nuclei are characterized by the $T_d^D$ ('double-tetrahedral') group of symmetry, exact or approximate. The corresponding strong shell-gap structure is markedly enhanced by the existence of the 4-dimensional irreducible representations of the group in question and consequently it can be seen as a geometrical effect that does not depend on a particular realization of the mean-field. Possibilities of discovering the corresponding symmetry in experiment are discussed.Comment: 4 pages in LaTeX and 4 figures in eps forma

Suscetibilidade de Elasmopalpus lignosellus ao milho transgênico (Bt).

Foram avaliados os híbridos de milho transgênico Herculex (Cry1F), Yieldgard Vtpro (Cry1A105,Cry2Ab2), Yieldgard (Cry1Ab) e Agrisure Viptera (Vip3A) na mortalidade, altura e massa seca da parte aérea e raiz de plantas de milho infestadas com lagartas de E. lignosellus.Resumo

Who I Am: The Meaning of Early Adolescents’ Most Valued Activities and Relationships, and Implications for Self-Concept Research

Self-concept research in early adolescence typically measures young people’s self-perceptions of competence in specific, adult-defined domains. However, studies have rarely explored young people’s own views of valued self-concept factors and their meanings. For two major self domains, the active and the social self, this mixed-methods study identified factors valued most by 526 young people from socioeconomically diverse backgrounds in Ireland (10-12 years), and explored the meanings associated with these in a stratified subsample (n = 99). Findings indicate that self-concept scales for early adolescence omit active and social self factors and meanings valued by young people, raising questions about content validity of scales in these domains. Findings also suggest scales may under-represent girls’ active and social selves; focus too much on some school-based competencies; and, in omitting intrinsically salient self domains and meanings, may focus more on contingent (extrinsic) rather than true (intrinsic) self-esteem

Impact of aerobic and resistance exercise combination on physical self-perceptions and self-esteem in women with obesity with one-year follow-up

The effectiveness of an exercise intervention including both aerobics and resistance training components in improving physical self-perceptions and global self-esteem (GSE) in women with obesity was examined. An experimental design with a one-year follow-up was used. Women with obesity (n = 72) participated in a structured exercise programme for 12 weeks after being randomised into a control and an exercise group. Exercise self-efficacy, body attractiveness, physical strength, sport competence, physical condition, physical self-worth, and GSE were measured at pre-intervention, early intervention, mid-intervention, immediately after the intervention, and five times following programme termination at 1, 3, 6, 9, and 12 months, respectively. Analyses of covariance revealed exercise effects for all of the dependent variables except for body attractiveness. Generally, exercise effects lasted between 6 and 12 months. A 12-week physical exercise programme including aerobic and resistance training components has the potential to improve physical self-perceptions and self-esteem in women with obesity