J.J. Rousseau i la lectura : del Robinson Crusoe a la literatura infantil

Resumen basado en el de la publicaci??n

Esquema nacional de seguridad

Lluís Ariño, miembro del Grupo de Administración Electrònica de la Conferencia de Rectores de las Universidades Españolas (CRUE), presenta la seguridad desde el punto de vista de la administración universitaria

Sintomas de Stress em Professores Brasileiros

O presente artigo pretende refletir e destacar os principais sintomas físicos e psicológicos de stress encontrados em professores das primeiras séries do ensino fundamental em escolas públicas estaduais de uma cidade brasileira. Exercer a atividade docente implica, para o professor, ter uma ocupação que exige certo grau de habilidade, preparo e conhecimento atualizado, ao mesmo tempo em que este profissional necessita praticar ações que desenvolvam as habilidades cognitivas, afetivas e sociais. A análise dos resultados obtidos indica que os sintomas de stress estão presentes na maioria dos professores, prevalecendo o stress na fase de resistência. A sintomatologia predominante foram os sintomas psicológicos, na qual se apresentam como mais significativos: a irritabilidade excessiva, pensar constantemente em um só assunto e sensibilidade emotiva excessiva. Na área física, os sintomas mais presentes foram: cansaço constante, sensação de desgaste físico constante e problemas com a memória.

An analysis of grammatical errors by children with cochlear implants

Spontaneous writing samples of deaf children with cochlear implants were analyzed for syntactic errors and other descriptive characteristics. These results were compared to a small sample of writings from hearing children.

Kipus: revista andina de letras. 10 (Reseñas)

Presenta las reseñas de los siguientes libros: Jorge Enrique Adoum, POESÍA VIVA DEL ECUADOR DEL SIGLO XX. ANTOLOGÍA, Quito: Libresa, 1998. -- Carolina Andrade, DE LUTO, Quito: Eskeletra; 123 pp. -- Jorge Dávila Vázquez, LA VIDA SECRETA, Cuenca: Universidad de Cuenca, 1999. Colección Triformidad No. 2, 57 pp. -- Rafael Díaz Ycaza, PROMETEO EL JOVEN Y OTRAS MORISQUETAS. Guayaquil: Casa de la Cultura Ecuatoriana, Núcleo del Guayas, 1997, 2a. edición. -- Mempo Giardinelli, LUNA CALIENTE, Quito: El Conejo, 1999; 108 pp. -- Efraín Jara Idrovo, EL MUNDO DE LAS EVIDENCIAS. OBRA POÉTICA l945-1998, Quito: Libresa / UASB, 1998. -- Alicia Ortega, LA CIUDAD Y SUS BIBLIOTECAS: EL GRAFFITI QUITEÑO Y LA CRÓNICA COSTEÑA, Quito: UASB Corporación Editora Nacional, 1999; 92 pp. -- Norberto Ras, EL GAUCHO Y LA LEY, Montevideo: Carlos Marchesi, editor, 1996; 128 pp. -- Mercedes Rowinsky, IMAGEN y DISCURSO: ESTUDIO DE LAS IMAGENES EN LA OBRA DE CRISTINA PERI ROSSI, Montevideo: Trilce. 1997; 224 pp. -- Javier Vásconez, UN EXTRAÑO EN EL PUERTO, Quito/México: Libri Mundi/ Alfaguara, 1998; 153 pp.

Force constants and dipole‐moment derivatives of molecules from perturbed Hartree–Fock calculations

General expressions for the force constants and dipole‐moment derivatives of molecules are derived, and the problems arising in their practical application are reviewed. Great emphasis is placed on the use of the Hartree–Fock function as an approximate wavefunction, and a number of its properties are discussed and re‐emphasised. The main content of this paper is the development of a perturbed Hartree–Fock theory that makes possible the direct calculation of force constants and dipole‐moment derivatives from SCF–MO wavefunctions. Essentially the theory yields ∂ϕi / ∂RJα, the derivative of an MO with respect to a nuclear coordinate.

Genesis and expansion of metazoan transcription factor gene classes

We know little about the genomic events that led to the advent of a multicellular grade of organization in animals, one of the most dramatic transitions in evolution. Metazoan multicellularity is correlated with the evolution of embryogenesis, which presumably was underpinned by a gene regulatory network reliant on the differential activation of signaling pathways and transcription factors. Many transcription factor genes that play critical roles in bilaterian development largely appear to have evolved before the divergence of cnidarian and bilaterian lineages. In contrast, sponges seem to have a more limited suite of transcription factors, suggesting that the developmental regulatory gene repertoire changed markedly during early metazoan evolution. Using whole- genome information from the sponge Amphimedon queenslandica, a range of eumetazoans, and the choanoflagellate Monosiga brevicollis, we investigate the genesis and expansion of homeobox, Sox, T- box, and Fox transcription factor genes. Comparative analyses reveal that novel transcription factor domains ( such as Paired, POU, and T- box) arose very early in metazoan evolution, prior to the separation of extant metazoan phyla but after the divergence of choanoflagellate and metazoan lineages. Phylogenetic analyses indicate that transcription factor classes then gradually expanded at the base of Metazoa before the bilaterian radiation, with each class following a different evolutionary trajectory. Based on the limited number of transcription factors in the Amphimedon genome, we infer that the genome of the metazoan last common ancestor included fewer gene members in each class than are present in extant eumetazoans. Transcription factor orthologues present in sponge, cnidarian, and bilaterian genomes may represent part of the core metazoan regulatory network underlying the origin of animal development and multicellularity.

Enhancing and diminishing gene function in human embryonic stem cells

It is widely recognized that gain- and loss-of-function approaches are essential for understanding the functions of specific genes, and such approaches would be particularly valuable in studies involving human embryonic stem (hES) cells. We describe a simple and efficient approach using lipofection to transfect hES cells, which enabled us to generate hES cell lines expressing naturally fluorescent green or red proteins without affecting cell pluripotency. We used these cell lines to establish a means of diminishing gene function using small interfering (si)RNAs, which were effective at knocking down gene expression in hES cells. We then demonstrated that stable expression of siRNA could knock down the expression of endogenous genes. Application of these gain- and loss-of-function approaches should have widespread use, not only in revealing the developmental roles of specific human genes, but also for their utility in modulating differentiation.

Oxidation affects the flow-induced aggregation of low density lipoprotein and its inhibition by albumin

We investigated whether oxidation alters the self-aggregation of low density lipoprotein (LDL) and the inhibition of such aggregation by albumin. Incubation with copper for different durations produced mildly, moderately, and highly oxidised LDL (having, respectively, ca. 60, 300 and 160 nmol lipid hydroperoxides/mg protein, and electrophoretic mobilities 1.2, 2.6 and 4.4 times that of native LDL). The rate of flow-induced aggregation was the same for native, mildly oxidised and moderately oxidised LDL, but decreased for highly oxidised LDL. The inhibitory effect of albumin (40 mg/ml) on aggregation was reduced by mild oxidation and further reduced by moderate or severe oxidation. The net result of the two effects was that in the presence of albumin, moderately oxidised LDL had the highest rate of aggregation and native the lowest. The reduction in the anti-aggregatory effect of albumin provides a new mechanism by which LDL oxidation might enhance net aggregation in vivo. (C) 2003 Elsevier B.V. All rights reserved.

Configurational preferences of two 1,2-diamine adducts of bis(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)cobalt(II)

The preparation, the IR and ligand field spectra and the structures of the mixed-ligand addition compounds [(N,N-dimethyl-1,2-diaminoethane)bis(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)cobalt(II)], [Co(thtf)2me2en], and [(N,N,N′,N′-tetramethyl-1,2-diaminoethane)bis(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)cobalt(II)], [Co(thtf)2me4en], are reported. The structures were determined by single crystal X-ray diffraction analysis (monoclinic, space group P21/c, Z=4 with a=10.708(6), b=19.531(6), c=13.352(6) Å, β=111.64(10)°, R1=0.0642 and wR2=0.1719 for [Co(thtf)2(me2en)] and a=12.033(6), b=15.565(6), c=15.339(6) Å, β=92.57(6)°, R1=0.0612 and wR2=0.1504 for [Co(thtf)2me4en]). The structures are distorted octahedral and the shortest cobalt–cobalt separation distances are 5.388(2) Å in [Co(thtf)2me2en] and 8.675(3) Å in [Co(thtf)2me4en]. In both compounds the diamine molecules attain the gauche conformation. The U(Z,Z) conformation of the β-dione leads to a semi-chair conformation of the β-dionato chelate rings. The relative orientation of the groups attached to the β-dionato moiety depends on the extent of stereoelectronic effects the N-substitution of the diamine entails. In [Co(thtf)2me2en] the intraligand distance separating the trifluoromethyl carbon atoms is 5.281(18) Å while in [Co(thtf)2me2en] it increases to 8.338(9) Å. The cobalt–cobalt separation distance, the orientation of the chelate rings and the extent of N-substitution seem to affect hydrogen bonding. While in [Co(thtf)2me2en] inter- and intraligand hydrogen bonding is implicated, it is totally absent in [Co(thtf)2me4en].

Complex history of a chromosomal paralogy region: insights from amphioxus aromatic amino acid hydroxylase genes and insulin-related genes

Aromatic amino acid hydroxylase (AAAH) genes and insulin-like genes form part of an extensive paralogy region shared by human chromosomes 11 and 12, thought to have arisen by tetraploidy in early vertebrate evolution. Cloning of a complementary DNA (cDNA) for an amphioxus (Branchiostoma floridae) hydroxylase gene (AmphiPAH) allowed us to investigate the ancestry of the human chromosome 11/12 paralogy region. Molecular phylogenetic evidence reveals that AmphiPAH is orthologous to vertebrate phenylalanine (PAH) genes; the implication is that all three vertebrate AAAH genes arose early in metazoan evolution, predating vertebrates. In contrast, our phylogenetic analysis of amphioxus and vertebrate insulin-related gene sequences is consistent with duplication of these genes during early chordate ancestry. The conclusion is that two tightly linked gene families on human chromosomes 11 and 12 were not duplicated coincidentally. We rationalize this paradox by invoking gene loss in the AAAH gene family and conclude that paralogous genes shared by paralogous chromosomes need not have identical evolutionary histories.