Search results for "Injection"
showing 10 items of 920 documents
Some Generalizations of a Simion Schmidt Bijection
2007
In 1985, Simion and Schmidt gave a constructive bijection φ from the set of all length (n-1) binary strings having no two consecutive 1s to the set of all length n permutations avoiding all patterns in {123,132,213}. In this paper, we generalize φ to an injective function from {0,1}n-1 to the set Sn of all length n permutations and derive from it four bijections φ : P →Q where P⊆{0,1}n-1 and Q ⊂ Sn. The domains are sets of restricted binary strings and the codomains are sets of pattern-avoiding permutations. As a particular case we retrieve the original Simion–Schmidt bijection. We also show that the bijections obtained are actually combinatorial isomorphisms, i.e. closeness-preserving bije…
Enhancer, chromatin insulator, non-coding RNA and α-histone gene expression during embryogenesis of the sea urchin Paracentrotus lividus.
2009
Core promoters and chromatin insulators (ins) may direct a transcriptional enhancer (enh) to prefer a specific promoter in complex genetic loci. Enh and ins flank the sea urchin Paracentrotus lividus α-histone H2A transcription unit in a tandem repeated cluster containing the five histone genes. In vivo competition assays of enh and ins functions reveal that the H2A enh-bound MBF-1 activator participates also in the expression of the H3 gene and that the sns5 ins buffers the downstream H1 promoter from the H2A enh. These results suggest that both the H2A enh and the sns5 ins may account for the diverse accumulation of the linker vs core nucleosomal histones during early development of the s…
Functional studies of regulatory genes in the sea urchin embryo.
2009
The sea urchin histone H2A enhancer-binding protein MBF-1 is needed for maximal expression also for the H3 gene, while is buffered by the sns5 insula…
2009
Enhancers are DNA elements which increase the transcription of associated gene in a position and distance independent manner relative to the transcription initiation site. Molecular mechanisms must operate to direct enhancers to specific promoters in complex genetic loci. The sea urchin a-histone genes are organized in several hundred tandem repeated units, each containing one copy of the five histone genes in the order 5’-H4-H2B-H3-H2A-H1-3’. Transcription is limited to the early cleavage and reaches its maximum at morula stage. After hatching these genes are repressed and maintained in the silenced state for whole life cycle of the animal. In Paracentrotus lividus, the MBF-1 activator bin…
A compact cis-regulatory module defines the exclusive expression of the Hbox12 homeobox-containing gene in the presumptive aboral ectoderm
2009
In the sea urchin embryo, a number of genes encoding transcription factors display territorial restricted expression. Among these, the zygotic Hbox12 homeobox gene is transiently transcribed in a limited number of cells of the animal-lateral half of the early Paracentrotus lividus embryo, whose descendants will constitute part of the ectoderm territory. We have explored the cis-regulatory apparatus of the gene and found that the intergenic region of the tandem Hbox12 repeats drives GFP expression in the presumptive aboral ectoderm and that a 234 bp fragment, defined Aboral Ectoderm Module, accounts for the restricted expression of the transgene. Within this module, a consensus sequence for …
Paleoenvironmental and tectonic evolution of the Liassic carbonate platform succession of Mt. Maranfusa (central western Sicily)
2011
The upper part of the Liassic carbonate platform succession (Inici Fm., Hettangian-Sinemurian), outcropping at Mt. Maranfusa (central western Sicily) consists of a sequence of peritidal limestones, overlain by Jurassic to Cenozoic pelagic limestones and their siliciclastic Tertiary covers. The good exposure of this succession, pertaining to the trapanese domain, in the area between Palermo and Sciacca mountains, allowed to study in detail the facies sequences and structural features of the carbonate platform and of the sedimentary dikes, in order to improve knowledge on its paleoenvironmental and tectonic evolution. The Inici Fm. is constituted by subtidal cyclic sequences of wackestone\pac…
Performances improvement of a S.I. CNG bi-fuel engine by means of double-fuel injection
2009
Natural gas represents today a promising alternative to conventional fuels for road vehicles propulsion, since it is characterized by a relatively low cost, better geopolitical distribution than oil, and lower environmental impact. This explains the current spreading of Compressed Natural Gas (CNG) fuelled S. I. engine, above all in the bi-fuel version, i.e. capable to run either with gasoline or with natural gas. This characteristic, on the one hand, permits the vehicle to go even when natural gas is not available, on the other hand requires the engine to be designed to run safely with gasoline, i.e. with compression ratio lower than what natural gas would allow. Moreover the electronic co…
Degradation od Mater-Bi/wood flour biocomposites in active sewage sludge
2009
A study via simulation of solidification during injection molding
2011
The final properties of an injection-molded part are strictly dependent on the solidification dynamics occurring during the processing. The experimental derivation of information about polymer solidification throughout the injection molding cycle is still an open challenge. To overcome the practical issues, the process simulation is proposed as a mean to derive useful data, and especially for identifying the most influencing parameters. The no-flow temperature (NFT) is a parameter used in most of injection molding simulation packages as a mean to determine whether the polymer flows or it is solid. With this simple parameter it is possible to take into account the rheological solidification …