Effects of Dehydration on Freezing Characteristics and Survival in Liquid Nitrogen of Three Recalcitrant Seeds

The recalcitrant seeds rambutan( Nephelium lappaceum). durian (Durio zibethinus) and cempedak (Artocarpus inleger) have a high critical moisture content (below which ·rapid loss of viability occurs of 27.0%, 26.0% and 37.9%,respectively. The critical moisture for embroys were higher at 39.0% for rambutan, 53.9% for durian and 43.2% for Cempedak. Differential Thermal analysis of the embroyos confirmed that their threshhold moistures (below which there is no freezable water) were lower than their critical moistureS. The Threshhold moistures for rambutan, durian and cempedak embryos were approximately 30%, 32% and 33% respectively. It is suggested that unsuccessful attempts at cryopreservation of embroyos of 'recalcitrant seeds in the past maybe due to the absence of safe window between the high critical moisture content and the threshhold moisture. This results in freezing injury at the higher moistures and dehydration injury' at the lower moistures. Potential techniques to overcome this and improve cryopreservation of recalcitrant seed embryos are discussed

Influences of source displacement on the features of subwavelength imaging of a photonic crystal slab

In this paper we study the characteristics of subwavelength imaging of a photonic crystal (PhC) superlens under the influence of source displacement. For square- and triangular-lattice photonic crystal lenses, we investigate the influence of changing the lateral position of a single point source on the imaging uniformity and stability. We also study the effect of changing the geometrical center of a pair of sources on the resolution of the double-image. Both properties are found to be sensitive to the displacement, which implies that a PhC slab cannot be treated seriously as a flat lens. We also show that by introducing material absorption into the dielectric cylinders of the PhC slab and widening the lateral width of the slab, the imaging uniformity and stability can be substantially improved. This study helps us to clarify the underlying mechanisms of some recently found phenomena concerning imaging instability.Comment: 6 pages, 4 figures. To appear in J. Phys. Cond. Mat

Optimal Energy Dissipation in Sliding Friction Simulations

Non-equilibrium molecular dynamics simulations, of crucial importance in sliding friction, are hampered by arbitrariness and uncertainties in the removal of the frictionally generated Joule heat. Building upon general pre-existing formulation, we implement a fully microscopic dissipation approach which, based on a parameter-free, non-Markovian, stochastic dynamics, absorbs Joule heat equivalently to a semi-infinite solid and harmonic substrate. As a test case, we investigate the stick-slip friction of a slider over a two-dimensional Lennard-Jones solid, comparing our virtually exact frictional results with approximate ones from commonly adopted dissipation schemes. Remarkably, the exact results can be closely reproduced by a standard Langevin dissipation scheme, once its parameters are determined according to a general and self-standing variational procedure

[Colored solutions of Yang-Baxter equation from representations of U_{q}gl(2)]

We study the Hopf algebra structure and the highest weight representation of a multiparameter version of $U_{q}gl(2)$. The commutation relations as well as other Hopf algebra maps are explicitly given. We show that the multiparameter universal ${\cal R}$ matrix can be constructed directly as a quantum double intertwiner, without using Reshetikhin's transformation. An interesting feature automatically appears in the representation theory: it can be divided into two types, one for generic $q$, the other for $q$ being a root of unity. When applying the representation theory to the multiparameter universal ${\cal R}$ matrix, the so called standard and nonstandard colored solutions $R(\mu,\nu; {\mu}', {\nu}')$ of the Yang-Baxter equation is obtained.Comment: [14]pages, latex, no figure

Application of GGBFS and Bentonite to Auto-Healing Cracks of Cement Paste

Cracks are caused by many factors. Shrinkage and external loading are the most common reason. It becomes a problem when the ingression of aggressive and harmful substance penetrates to the concrete gap. This problem reduces the durability of the structures. It is well known that self – healing of cracks significantly improves the durability of the concrete structure. This paper presents self-healing cracks of cement paste containing bentonite associated with ground granulated blast furnace slag. The self-healing properties were evaluated with four parameters: crack width on the surface, crack depth, tensile strength recovery, and flexural recovery. In combination with microscopic observation, a healing process over time is also performed. The results show that bentonite improves the healing properties, in terms of surface crack width and crack depth. On the other hand, GGBFS could also improve the healing process, in terms of crack depth, direst tensile recovery, and flexural stiffness recovery. Carbonation reaction is believed as the main mechanism, which contributes the self-healing process as well as the continuous hydration progress

Imaging propagative exciton polaritons in atomically thin WSe2 waveguides

The exciton polariton (EP) is a half-light and half-matter quasiparticle that is promising for exploring both fundamental quantum phenomena as well as photonic applications. Van der Waals materials, such as transition-metal dichalcogenide (TMD), emerge as a promising nanophotonics platform due to its support of long propagative EPs even at room temperature. However, real-space studies have been limited to bulk crystal waveguides with a thickness no less than 60 nm. Here we report the nano-optical imaging of the transverse-electric EPs in WSe2 nanoflakes down to a few atomic layers, which can be turned on and off by tuning the polarization state of the excitation laser. Unlike previously studied transverse-magnetic modes that exist only in bulk TMD waveguides, we found that the transverse-electric EPs could reside in ultrathin WSe2 samples, owing to the alignment of the electric field with the in-plane dipole orientation of two-dimensional excitons. Furthermore, we show that the EP wavelength and propagation length can be largely controlled by varying laser energy and sample thickness. These findings open opportunities to realize near-infrared polaritonic devices and circuits truly at the atomically thin limit

Plug-and-play genetic access to drosophila cell types using exchangeable exon cassettes.

Genetically encoded effectors are important tools for probing cellular function in living animals, but improved methods for directing their expression to specific cell types are required. Here, we introduce a simple, versatile method for achieving cell-type-specific expression of transgenes that leverages the untapped potential of "coding introns" (i.e., introns between coding exons). Our method couples the expression of a transgene to that of a native gene expressed in the cells of interest using intronically inserted "plug-and-play" cassettes (called "Trojan exons") that carry a splice acceptor site followed by the coding sequences of T2A peptide and an effector transgene. We demonstrate the efficacy of this approach in Drosophila using lines containing suitable MiMIC (Minos-mediated integration cassette) transposons and a palette of Trojan exons capable of expressing a range of commonly used transcription factors. We also introduce an exchangeable, MiMIC-like Trojan exon construct that can be targeted to coding introns using the Crispr/Cas system.This work was supported by the Intramural Research Program of the National Institute of Mental Health (B.H.W.) and by grants from the Whitehall Foundation (C.J.P.), NIH (R01DC013070, C.J.P.), the Wellcome Trust (H.I. and M.L.), and the Sir Isaac Newton Trust, Cambridge (M.L.). J.E. was supported by FONDECYT #1141278 and the CINV, which is supported by the Millennium Scientific Initiative of the Ministerio de Economía, Fomento y Turismo. We thank the Bellen laboratory and the Drosophila Gene Disruption Project at Baylor College of Medicine, the Bloomington Stock Center (NIH P40OD018537), and Julie Simpson for fly lines. Thanks also to Aaron DiAntonio, Aaron Hsueh, and John Reinitz for antibodies and the NINDS Sequencing Core Facility for DNA sequencing. Finally, thanks to Sarah Naylor for technical help and Grace Gray, Herman Dierick, Koen Venken, and Hugo Bellen for comments on the manuscript and productive discussions.This is the final published version. It first appeared at http://www.ncbi.nlm.nih.gov/pubmed/25732830

A reflexão como um instrumento de formação no PFCM

O Programa de Formação Contínua em Matemática para Professores dos 1.º e 2.º Ciclos do Ensino Básico (PFCM), com o objectivo de melhorar o ensino e as aprendizagens em Matemática e desenvolver atitudes mais positivas face a esta área do saber, pretende responder às necessidades dos professores participantes, partindo de questões relativas à concretização do currículo de Matemática na sala de aula e tendo um carácter continuado ao longo do ano lectivo. O PFCM constitui, assim, um instrumento de apoio e ajuda aos professores participantes na sua prática lectiva (planificação do trabalho, condução da aula, reflexão sobre o que foi feito) de modo a melhorar as suas actuações profissionais e, consequentemente, as aprendizagens matemáticas dos seus alunos. No anterior ano lectivo, o plano de formação desenvolvido pela Escola Superior de Educação de Bragança (ESEB), embora possibilitasse a abordagem de qualquer conteúdo de formação previsto, centrou-se em alguns domínios, nomeadamente, na clarificação ou aprofundamento de temas matemáticos, na discussão dos tipos e natureza das tarefas (exercícios, explorações, problemas, investigações; jogos, projectos), em aspectos da comunicação matemática, na utilização de materiais curriculares, e na construção dos portefólios, valorizando os registos escritos e reflexão. Nesta comunicação pretendemos discutir, com base na observação participante e na análise documental, situações e episódios ocorridos nas salas de aula que fundamentem aspectos do ensino e aprendizagem da Matemática destacados pelo plano de formação da ESEB e evidenciados quer pelos formadores quer pelos professores participantes, dando especial relevância à reflexão (pessoal e partilhada) sobre as experiências profissionais