Search results for " complement"

Spacelike energy of timelike unit vector fields on a Lorentzian manifold

2004

On a Lorentzian manifold, we define a new functional on the space of unit timelike vector fields given by the L2 norm of the restriction of the covariant derivative of the vector field to its orthogonal complement. This spacelike energy is related with the energy of the vector field as a map on the tangent bundle endowed with the Kaluza–Klein metric, but it is more adapted to the situation. We compute the first and second variation of the functional and we exhibit several examples of critical points on cosmological models as generalized Robertson–Walker spaces and Godel universe, on Einstein and contact manifolds and on Lorentzian Berger’s spheres. For these critical points we have also stu…

Calculus Artefacts in Chinese Textbooks: Variational Approaches with Prospective Primary Teachers

2022

The first part of the paper presents some theoretical reflections and some methodological notes about a Professional Development (PD) path worked out during the last two years by Italian researchers for prospective primary teachers. The theoretical construct of Cultural Transposition defines the framework of the PD path’s activities and the related research. It was used to define an interesting cultural lens to delineate possible new approaches for effective pre-service teacher education programs in particular for the primary level. The defined methodology was based on the possibility to reflect on the he decentralization of didactic practices based on a specific cultural context through on…

Heterogeneous network games: Conflicting preferences

2013

Proceeding at: 2nd Annual UECE Lisbon Meeting: Game Theory and Applications, took place 2010, November, 4-6, in Lisbon (Portugal). The event Web site http://pascal.iseg.utl.pt/~uece/lisbonmeetings2010/ In many economic situations, a player pursues coordination or anti-coordination with her neighbors on a network, but she also has intrinsic preferences among the available options. We here introduce a model which allows to analyze this issue by means of a simple framework in which players endowed with an idiosyncratic identity interact on a social network through strategic complements or substitutes. We classify the possible types of Nash equilibria under complete information, finding two thr…

Epistemic and didactic values of the demonstrative process in different cultures: a case study in Geometry with Chinese and Italian students

2011

A G468-T AMPD1 mutant allele contributes to the high incidence of myoadenylate deaminase deficiency in the Caucasian population.

2002

Myoadenylate deaminase deficiency is the most common metabolic disorder of skeletal muscle in the Caucasian population, affecting approximately 2% of all individuals. Although most deficient subjects are asymptomatic, some suffer from exercise-induced myalgia suggesting a causal relationship between a lack of enzyme activity and muscle function. In addition, carriers of this derangement in purine nucleotide catabolism may have an adaptive advantage related to clinical outcome in heart disease. The molecular basis of myoadenylate deaminase deficiency in Caucasians has been attributed to a single mutant allele characterized by double C to T transitions at nucleotides +34 and +143 in mRNA enco…

Fluorescence Properties of the Chromophore-Binding Domain of Bacteriophytochrome from Deinococcus radiodurans

2013

Fluorescent proteins are versatile tools for molecular imaging. In this study, we report a detailed analysis of the absorption and fluorescence properties of the chromophore-binding domain from Deinococcus radiodurans and its D207H mutant. Using single photon counting and transient absorption techniques, the average excited state lifetime of both studied systems was about 370 ps. The D207H mutation slightly changed the excited state decay profile but did not have a considerable effect on the average decay time of the system or the shape of the absorption and emission spectra of the biliverdin chromophore. We confirmed that the fluorescence properties of both samples are very similar in vivo…

Role of tir and intimin in the virulence of rabbit enteropathogenic Escherichia coli serotype O103:H2.

2000

ABSTRACT Attaching and effacing (A/E) rabbit enteropathogenic Escherichia coli (REPEC) strains belonging to serogroup O103 are an important cause of diarrhea in weaned rabbits. Like human EPEC strains, they possess the locus of enterocyte effacement clustering the genes involved in the formation of the A/E lesions. In addition, pathogenic REPEC O103 strains produce an Esp-dependent but Eae (intimin)-independent alteration of the host cell cytoskeleton characterized by the formation of focal adhesion complexes and the reorganization of the actin cytoskeleton into bundles of stress fibers. To investigate the role of intimin and its translocated coreceptor (Tir) in the pathogenicity of REPEC, …

Sus1, a functional component of the SAGA histone acetylase complex and the nuclear pore-associated mRNA export machinery

2004

12 páginas, 7 figuras, 1 tabla. Material suplementario en: https://doi.org/10.1016/S0092-8674(03)01025-0. The SUS1 sequences have been deposited in GenBank with the accession number AY278445.

The modulator is a constitutive enhancer of a developmentally regulated sea urchin histone H2A gene.

2002

Going back to the late 1970s and early 1980s, we trace the Xenopus oocyte microinjection experiments that led to the emergence of the concept of “modulator”. The finding that the modulator could transactivate transcription from far upstream and in either orientation suggested that a new genetic element, different from the classical prokaryotic promoter sequences, had been discovered. This particular enhancer transactivates transcription of the sea urchin early (α) histone H2A gene which is regulated in early sea urchin development. We summarise the data from sea urchin microinjection experiments that confirm and extend the results obtained with Xenopus oocytes. We conclude that the H2A enha…

Aberrant splicing of the Drosophila melanogaster phenylalanine hydroxylase pre-mRNA caused by the insertion of a B104/roo transposable element in the…

1999

Abstract We report the insertion of the transposable element B104 in the Phenylalanine hydroxylase gene of the Drosophila mutant Henna-recessive 3 . Its presence alters the Phenylalanine hydroxylase splicing pattern, producing at least two aberrant mRNAs which contain part of the B104 sequence interrupting the coding region. This aberrant splicing is provoked by the use of a cryptic donor site encoded by the B104 3′ long terminal repeat in combination with either the gene intron 3 acceptor site or a novel acceptor site generated by the target duplication caused by transposition. One of them, referred as mRNA type 1, encodes a truncated protein that could be predictably non-functional. In mR…