A Complete Perturbative Expansion for Constrained Quantum Dynamics

A complete perturbative expansion for the Hamiltonian describing the motion of a quantomechanical system constrained to move on an arbitrary submanifold of its configuration space $R^n$ is obtained.Comment: 18 pages, LaTe

The splicing regulators Tra and Tra2 are unusually potent activators of pre-mRNA splicing

Sexual differentiation in Drosophila is regulated through alternative splicing of doublesex. Female-specific splicing is activated through the activity of splicing enhancer complexes assembled on multiple repeat elements. Each of these repeats serves as a binding platform for the cooperative assembly of a heterotrimeric complex consisting of the SR proteins Tra, Tra2 and 9G8. Using quantitative kinetic analyses, we demonstrate that each component of the enhancer complex is capable of recruiting the spliceosome. Surprisingly, Tra, Tra2 and 9G8 are much stronger splicing activators than other SR protein family members and their activation potential is significantly higher than expected from their serine/arginine content. 9G8 activates splicing not only through its RS domains but also through its RNA-binding domain. The RS domains of Tra and Tra2 are required but not sufficient for efficient complex assembly. Thus, the regulated assembly of the dsx enhancer complexes leads to the generation of an extended activation domain to guarantee the ‘all or none’ splicing switch that is required during Drosophila sexual differentiation

Haplotype profile comparisons cetween Spodoptera frugiperda (Lepidoptera: Noctuidae) populations from Mexico with those from Puerto Rico, South America, and the United States and their implications to migratory behavior

Fall armyworm [Spodoptera frugiperda (J. E. Smith)] is a major economic pest throughout the Western Hemisphere of maize, cotton, sorghum, and a variety of agricultural grasses and vegetable crops. Previous studies demonstrated extensive annual migrations occurring as far north as Canada from overwintering locations in southern Florida and Texas. In contrast, migratory behavior in the rest of the hemisphere is largely uncharacterized. Understanding the migration patterns of fall armyworm will facilitate efforts to predict the spread of pesticide resistance traits that repeatedly arise in this species and assess the consequences of changing climatic trends on the infestation range. Four independent fall armyworm colonies derived from widely separated populations in Mexico and two field collections were examined for their mitochondrial cytochrome oxidase I (COI) gene haplotypes and compared with other locations. The Mexico populations were most similar in their haplotype profile to those from Texas and South America, but also displayed some distinctive features. The data extend the haplotype distribution map in the Western Hemisphere and confirm that the previously observed regional differences in haplotype frequencies are stable over time. The Mexico collections were associated with haplotypes rarely found elsewhere, suggesting limited migratory interactions with foreign populations, including those in neighboring Texas.Fil: Nagoshi, Rodney N.. United States Department Of Agriculture. Agricultural Research Service; ArgentinaFil: Rosas Garcia, Ninfa M.. Instituto Politécnico Nacional; MéxicoFil: Meagher, Robert L.. United States Department Of Agriculture. Agricultural Research Service; ArgentinaFil: Fleischer, Shelby J.. State University Of Pennsylvania; Estados UnidosFil: Westbrook, John K.. United States Department Of Agriculture. Agricultural Research Service; ArgentinaFil: Sappington, Thomas W.. United States Department Of Agriculture. Agricultural Research Service; ArgentinaFil: Hay Roe, Mirian. United States Department Of Agriculture. Agricultural Research Service; ArgentinaFil: Thomas, Jean M. G.. United States Department Of Agriculture. Agricultural Research Service; ArgentinaFil: Murúa, María Gabriela. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Doping Dependence of the Electronic Structure of Ba_{1-x}K_{x}BiO_{3} Studied by X-Ray Absorption Spectroscopy

We have performed x-ray absorption spectroscopy (XAS) and x-ray photoemission spectroscopy (XPS) studies of single crystal Ba_{1-x}K_{x}BiO_{3} (BKBO) covering the whole composition range $0 \leq x \leq 0.60$. Several features in the oxygen 1\textit{s} core XAS spectra show systematic changes with $x$. Spectral weight around the absorption threshold increases with hole doping and shows a finite jump between $x=0.30$ and 0.40, which signals the metal-insulator transition. We have compared the obtained results with band-structure calculations. Comparison with the XAS results of BaPb_{1-x}Bi_{x}O_{3} has revealed quite different doping dependences between BKBO and BPBO. We have also observed systematic core-level shifts in the XPS spectra as well as in the XAS threshold as functions of $x$, which can be attributed to a chemical potential shift accompanying the hole doping. The observed chemical potential shift is found to be slower than that predicted by the rigid band model based on the band-structure calculations.Comment: 8 pages, 8 figures include

Probe of bending motion following the 1s[–1]π* excitation of N2O

The doubly degenerate core-excitedΠ state of N2O splits into two due to the static Renner–Teller effect. The lower state, A1, has a bent stable geometry and the molecule excited to this state starts to deform itself toward this bent geometry. To probe the effect of the potential energy surfaces of the core-excited A1 states on the nuclear motion, we measure the momenta of the three atomic ions in coincidence by means of the ion momentum imaging technique. We find that the potential energy surface affects the molecular deformation significantly. N2O in the terminal N 1s[–1]3πA1 excited state is observed to be bent more than that in the central N 1s[–1]3πA1 excited state. This means that N2O in the terminal N 1s[–1]3πA1 excited state bends faster than that in the central N 1s[–1]3πA1 excited state. When the excitation energy is decreased within the 1s[–1]3π resonances, the nuclear motion in the A1 states becomes faster. This is interpreted by the notion that the excitation occurs onto the steeper slope part of the potential energy surface of the excited state for the lower excitation energy. The branching ratio of the A1 excitation increases with the decrease in the excitation energy. ©2004 American Institute of Physics

Enteric Neurospheres Are Not Specific to Neural Crest Cultures: Implications for Neural Stem Cell Therapies

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited

Schwann-Spheres Derived from Injured Peripheral Nerves in Adult Mice - Their In Vitro Characterization and Therapeutic Potential

Multipotent somatic stem cells have been identified in various adult tissues. However, the stem/progenitor cells of the peripheral nerves have been isolated only from fetal tissues. Here, we isolated Schwann-cell precursors/immature Schwann cells from the injured peripheral nerves of adult mice using a floating culture technique that we call “Schwann-spheres." The Schwann-spheres were derived from de-differentiated mature Schwann cells harvested 24 hours to 6 weeks after peripheral nerve injury. They had extensive self-renewal and differentiation capabilities. They strongly expressed the immature-Schwann-cell marker p75, and differentiated only into the Schwann-cell lineage. The spheres showed enhanced myelin formation and neurite growth compared to mature Schwann cells in vitro. Mature Schwann cells have been considered a promising candidate for cell-transplantation therapies to repair the damaged nervous system, whereas these “Schwann-spheres" would provide a more potential autologous cell source for such transplantation

Genetic studies of fall armyworm indicate a new introduction into Africa and identify limits to its migratory behavior

Open Access Journal; Published online: 04 Feb 2022The fall armyworm, Spodoptera frugiperda (J.E. Smith) is native to the Americas and a major pest of corn and several other crops of economic importance. The species has characteristics that make it of particular concern as an invasive pest, including broad host range, long-distance migration behavior, and a propensity for field-evolved pesticide resistance. The discovery of fall armyworm in western Africa in 2016 was followed by what was apparently a remarkably rapid spread throughout sub-Saharan Africa by 2018, causing economic damage estimated in the tens of billions USD and threatening the food security of the continent. Understanding the history of the fall armyworm invasion of Africa and the genetic composition of the African populations is critical to assessing the risk posed to different crop types, the development of effective mitigation strategies, and to make Africa less vulnerable to future invasions of migratory moth pests. This paper tested and expanded on previous studies by combining data from 22 sub-Saharan nations during the period from 2016 to 2019. The results support initial descriptions of the fall armyworm invasion, including the near absence of the strain that prefers rice, millet, and pasture grasses, while providing additional evidence that the magnitude and extent of FAW natural migration on the continent is more limited than expected. The results also show that a second entry of fall armyworm likely occurred in western Africa from a source different than that of the original introduction. These findings indicate that western Africa continues to be at high risk of future introductions of FAW, which could complicate mitigation efforts

Fall Armyworm (Spodoptera frugiperda)

The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), originated from America but is reported recently from Africa and the Asia-Pacific. FAW has caused huge international concern since its outbreak in Africa since 2016 and in Asia since mid-2018. The chapter mainly reviews its global distribution, life cycle, identification characters, strains, host plants, nature of damage, economic damage, and integrated pest management strategies available. The pest completes its life cycle on maize in 30 days (in warm summer months); in cooler temperatures, it may extend up to 60–90 days. For effective management of fall armyworm, different tools, viz., cultural control, agronomic management, breeding for resistance, natural enemies, and eco-friendly insecticides, should be used in an integrated approach. As the insect is recently introduced to Africa and the Asia-Pacific, possible management strategies and future cases of action are discussed