A new look at energy release rates for quasistatically propagating cracks in inelastic materials

A mapping technique is used to derive an integral expression for the energy release rate for a quasistatically propagating crack. The derivation does not depend on any assumptions in regard to the contitutive behavior of the material. It leads to a contour integral around the crack tip, plus an area integral over the region enclosed by this contour. Only the stress and displacement fields appear in the integrands. Although for stationary crack solutions known to the authors the area integral is not convergent, for propagating crack solutions in elastoplastic material, the integrals are convergent, and lead to zero energy release rate. This confirms conclusions by Rice from an independent point of view.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42773/1/10704_2004_Article_BF00012388.pd

Does congenital deafness affect the structural and functional architecture of primary visual cortex?

Deafness results in greater reliance on the remaining senses. It is unknown whether the cortical architecture of the intact senses is optimized to compensate for lost input. Here we performed widefield population receptive field (pRF) mapping of primary visual cortex (V1) with functional magnetic resonance imaging (fMRI) in hearing and congenitally deaf participants, all of whom had learnt sign language after the age of 10 years. We found larger pRFs encoding the peripheral visual field of deaf compared to hearing participants. This was likely driven by larger facilitatory center zones of the pRF profile concentrated in the near and far periphery in the deaf group. pRF density was comparable between groups, indicating pRFs overlapped more in the deaf group. This could suggest that a coarse coding strategy underlies enhanced peripheral visual skills in deaf people. Cortical thickness was also decreased in V1 in the deaf group. These findings suggest deafness causes structural and functional plasticity at the earliest stages of visual cortex

Localization of the murine cholecystokinin A and B receptor genes

We have determined the chromosomal locations of the two cholecystokinin (CCK) receptor genes in the mouse. Genetic localization utilized an interspecific backcross panel formed from the cross (C57BL/6J x Mus spretus ) F 1 x Mus spretus . Genomic DNAs from 94 individuals in the backcross were analyzed by Southern hybridization with rat CCK A and CCK B receptor cDNA probes. Unique map positions were determined by haplotype analysis with 650 previously mapped loci in the mouse backcross. The CCK A receptor gene ( Cckar ) mapped to mouse Chromosome (Chr) 5, in tight linkage with the DNA marker D5Bir8 . The CCK B receptor gene ( Cckbr ) mapped to mouse Chr 7, tightly linked to the β-hemoglobin locus ( Hbb ). This localization places Cckbr in the same region as the mouse obesity mutation tubby ( tub ), which also maps near Hbb (2.4±1.4 cM). Since CCK can function as a satiety factor when administered to rodents, localization of Cckbr near the tub mutation identifies this receptor as a possible candidate gene for this obesity mutation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47021/1/335_2004_Article_BF00352408.pd

Pteridófitas da Serra Negra, Minas Gerais, Brasil

Este trabalho apresenta uma lista de espécies de pteridófitas que ocorrem na Serra Negra, Minas Gerais. A serra está inserida no complexo da Serra da Mantiqueira situada entre Rio Preto, Lima Duarte, Santa Bárbara do Monte Verde e Olaria, tendo seus limites nos pontos 21º58'11"S 43º53'21" W, 22º01'46,4" S 43º52'31,5" W, 21º58'21,4" S 43º50'06,5" W e 21º58'53" S 43º56'08" W. A vegetação da serra é formada por um mosaico de fitofisionomias, sendo encontradas formações florestais (florestas ombrófilas e semidecíduas) e campestres (campos rupestres). O inventário florístico foi realizado entre os anos de 2003 e 2008, em excursões mensais para coleta de amostras e registro de dados. Na serra foram registradas 209 táxons infragenéricos distribuídas em 24 famílias e 75 gêneros. As famílias com maior número de espécies foram Polypodiaceae (40), Dryopteridaceae (33) e Pteridaceae (25). A maioria das espécies (109) foi encontrada ocorrendo exclusivamente no interior de floresta. Em relação ao hábito, 69 espécies foram encontradas exclusivamente como terrestres, 37 como rupícolas ou terrestres e 32 exclusivamente epífitas. Este trabalho revela uma elevada riqueza de pteridófitas na região e indica a importância de estudos desta natureza na conservação e manejo das pteridófitas em Minas Gerais.This work presents an inventory of pteridophyte species that occur in the Serra Negra, of Minas Gerais. The area is part of the Mantiqueira Range, and is situated between the coordinates 21º58'11"S 43º53'21" W, 22º01'4.4" S, 43º52'31.5" W, 21º58'21.4" S, 43º50'06.5" W and 21º58'53" S, 43º56'08" W. The vegetation in the Serra Negra is characterized by a mosaic of different phytophysiognomies, divided into forests (evergreen and seasonal semideciduous forests) and open formations (rocky grasslands). The inventory was carried out from 2003 to 2008, during monthly excursions to collect botanical material and data in the study area. A total of 209 species, distributed in 24 families and 75 genera, were recorded. The families with the highest number of species were Polypodiaceae (40), Dryopteridaceae (33) and Pteridaceae (25). More than the half (110) of the inventoried species were recorded exclusively in the forests formations. Sixty-nine species were terrestrial, 37 were saxicolous or terrestrial and 32 were epiphytes. This work shows that this region is rich in ferns and reveals the importance of this kind of study for conservation and management of pteridophytes in the state of Minas Gerais

Wavelet analysis of gene expression (WAGE)

The wavelet transform (WT) is the mathematical operator of choice for the analysis of nonstationary signals. At the same time, it is also a modelling operator that may be used to impose functional constraints on data to unveil hidden groupings and relationships. In this work, we apply the WT to the chromosomal sequences of gene expression values measured with microarray technology. The application of the wavelet operator aims to uncover clusters of genes that interact by vicinity, either because of a shared regulatory mechanism or because of common susceptibility to environmental factors. Application of the method to data on the expression of human brain genes in neuro-degeneration validates the technique and, at the same time, illustrates the potential of the method