13,818 research outputs found
Yangians, Grassmannians and T-duality
We investigate the Yangian symmetry of scattering amplitudes in N=4 super
Yang-Mills theory and show that its formulations in twistor and momentum
twistor space can be interchanged. In particular we show that the full symmetry
can be thought of as the Yangian of the dual superconformal algebra,
annihilating the amplitude with the MHV part factored out. The equivalence of
this picture with the one where the ordinary superconformal symmetry is thought
of as fundamental is an algebraic expression of T-duality. Motivated by this,
we analyse some recently proposed formulas, which reproduce different
contributions to amplitudes through a Grassmannian integral. We prove their
Yangian invariance by directly applying the generators.Comment: 28 pages, 1 figure; v2: minor correction
Fifteen new species of Sonoma Casey from the eastern United States and a description of the male of Sonoma tolulae (LeConte) (Coleoptera: Staphylinidae: Pselaphinae)
Fifteen new species of faronine pselaphines in the genus Sonoma Casey are described: S. baylessae; S. brasstownensis; S. chouljenkoi; S. cygnus; S. gilae; S. gimmeli; S. holmesi; S. mayori; S. nicholsae; S. parkorum; S. nhunguyeni; S. sokolovi; S. streptophorophallus; S. tishechkini; S. tridens. Male specimens of Sonoma tolulae (LeConte) were collected from the type locality and this species is redescribed. These species bring the total diversity of the genus to 43 species. The genus is divided into four species groups based on characters of the male genitalia. Sonoma corticina Casey was not included in the genus when it was described, thus it cannot be the type species of the genus. We here designate Sonoma tolulae (LeConte) as the type species of the genus Sonoma. A key is provided that will allow discrimination of all eastern species. Life history, habitat, and collection techniques are discussed
Contributions to the faunistics of Odonata in Thailand
Distribution and habitat information are provided for 1578 adult specimens of Odonata representing 127 species in 70 genera and 16 families that were collected from 143 locations throughout Thailand. Of the species collected, 25 (20%) were represented by a single specimen, and 40 (31%) were collected from a single location. Collections were made at 49 lentic and 85 lotic sites, and an average of 6.9 and 6.6 species were collected at each site in each habitat, respectively
Reduction of Lie--Jordan algebras: Quantum
In this paper we present a theory of reduction of quantum systems in the
presence of symmetries and constraints. The language used is that of
Lie--Jordan Banach algebras, which are discussed in some detail together with
spectrum properties and the space of states. The reduced Lie--Jordan Banach
algebra is characterized together with the Dirac states on the physical algebra
of observables
Comparison of three collection techniques for capture of Coleoptera, with an emphasis on saproxylic species, in Great Smoky Mountains National Park, USA
Collection methods and/or habitats sampled influence how many and which species are captured during entomological surveys. Here we compare Coleoptera catches among three survey activities, each using a single collection method, at the same study sites in Great Smoky Mountains National Park, USA. Activities included: short-term flight intercept trapping (FITs); sifting/Berlese funneling of leaf litter and extremely decayed downed coarse woody debris; and using emergence chambers containing coarse woody debris of various decay classes. In total, 2472 adult beetle specimens, representing 217 lowest identifiable taxa within 164 genera and 42 families, were collected during the FIT survey. Each survey activity yielded more than 2000 specimens, and a combined total of 413 species was collected. A combination of all surveys yielded the highest species richness when normalized for number of specimens indicating that variation of habitat and/or collection method significantly increases species richness. Of single surveys the FIT survey had the highest absolute species richness (217) and the highest richness when normalized for number of specimens. Species overlap among survey activities was low (Sorensen’s quotient of similarity was 0.20–0.27), which showed that each was about equally dissimilar from all others. Overlap of catch between FITs and emergence chambers was too low to justify substitution of emergence surveys with the FIT survey protocol used when attempting to collect saproxylic Coleoptera
An investigation of the beneficial effects of adding carbon nanotubes to standard injection grout
Mortar grouting is often used in masonry constructions to mitigate structural decay and repair damage by filling cracks and voids, resulting in an improvement in mechanical properties. This paper presents an original experimental investigation on grout with added carbon nanotubes (CNTs). The samples were prepared with different percentages of CNTs, up to 1.2 wt% with respect to the binder, and underwent three‐point bending tests in crack mouth opening displacement mode and compressive tests. The results showed that very small additions (up to 0.12 wt% of CNTs) increased not only flexural and compressive strengths (+73% and 35%, respectively, in comparison with plain mortar) but also fracture energy (+80%). These results can be explained on the basis of a reduction in porosity, as evidenced by mercury intrusion porosimetry, as well as by a crack bridging mechanism and by the probable formation of nucleation sites for hydration products, as observed through scanning electron microscopy
New state records for Coniopterygidae (Neuroptera) with an updated list of species in North America north of Mexico
Coniopterygidae are the smallest members of the order Neuroptera and are often overlooked by collectors. Consequently, distribution of many species within North America north of Mexico is poorly known, even at the state level. Currently 57 species (five adventive) are recognized from North America. Of those, 30 are reported from a single state or province. Conversely, 12 states and provinces have no published records of Coniopterygidae. More than 600 specimens of adult coniopterygids were identified and numerous new state records were determined. An updated list of species state-level distribution is provided.
Los Coniopterygidae son los miembros más pequeños del orden Neuroptera y con frecuencia son ignorados por los recolectores. Por tanto, la distribución de muchas especies en Norteamérica al norte de México es escasamente conocida, aún al nivel estatal. Actualmente 57 especies (cinco adventicias) se reconocen de Norteamérica. De estas, 30 se reportan de un solo estado o provincia. A la inversa, 12 estados y provincias no tienen registros publicados de Coniopterygidae. Más de 600 ejemplares de coniopterígidos adultos fueron identificados y numerosos nuevos registros de estado fueron determinados. Una lista actualizada de especies con distribución por estado es proporcionada
Music and Autism Spectrum Disorder: Possible Effects on the Autistic Mind
Autism Spectrum Disorder (ASD) is a known neurological disorder that directly affects an individual\u27s ability to communicate and interact with others; ASD is diagnosed within the first three years of life. One of the most common forms of therapy or interventions used is music. Music incorporation can change in a format such as learning a specific instrument, singing, or simply dancing to promote physical activity to help brain stimulation and process the overall musical experience. Music has been a commonly used therapy or intervention for children diagnosed with ASD dating back to the mid-1940s. Those diagnosed with ASD have difficulty with social interactions, communication, and emotional expression, all of which occur naturally in the music learning and music-making process. One of the more popular music therapy forms is improvisational music therapy, specifically relating to ASD. By allowing those with ASD a more flexible approach to music learning, the students can exercise social, communicative, and problem-solving skills at a pace set by the instructor or therapist for the students\u27 benefit. Utilizing elements of Orff and Kodály methods of music learning will allow students with ASD an opportunity to flourish
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