The acceptance of online graduate coursework by school districts in Wisconsin and Illinois

Includes bibliographical references

Dense Packings of Congruent Circles in Rectangles with a Variable Aspect Ratio

We use computational experiments to find the rectangles of minimum area into which a given number n of non-overlapping congruent circles can be packed. No assumption is made on the shape of the rectangles. Most of the packings found have the usual regular square or hexagonal pattern. However, for 1495 values of n in the tested range n =< 5000, specifically, for n = 49, 61, 79, 97, 107,... 4999, we prove that the optimum cannot possibly be achieved by such regular arrangements. The evidence suggests that the limiting height-to-width ratio of rectangles containing an optimal hexagonal packing of circles tends to 2-sqrt(3) as n tends to infinity, if the limit exists.Comment: 21 pages, 13 figure

Differential behavioral state-dependence in the burst properties of CA3 and CA1 neurons

Brief bursts of fast high-frequency action potentials are a signature characteristic of CA3 and CA1 pyramidal neurons. Understanding the factors determining burst and single spiking is potentially significant for sensory representation, synaptic plasticity and epileptogenesis. A variety of models suggest distinct functional roles for burst discharge, and for specific characteristics of the burst in neural coding. However, little in vivo data demonstrate how often and under what conditions CA3 and CA1 actually exhibit burst and single spike discharges. The present study examined burst discharge and single spiking of CA3 and CA1 neurons across distinct behavioral states (awake-immobility and maze-running) in rats. In both CA3 and CA1 spike bursts accounted for less than 20% of all spike events. CA3 neurons exhibited more spikes per burst, greater spike frequency, larger amplitude spikes and more spike amplitude attenuation than CA1 neurons. A major finding of the present study is that the propensity of CA1 neurons to burst was affected by behavioral state, while the propensity of CA3 to burst was not. CA1 neurons exhibited fewer bursts during maze running compared with awake-immobility. In contrast, there were no differences in burst discharge of CA3 neurons. Neurons in both subregions exhibited smaller spike amplitude, fewer spikes per burst, longer inter-spike intervals and greater spike amplitude attenuation within a burst during awake-immobility compared with maze running. These findings demonstrate that the CA1 network is under greater behavioral state-dependent regulation than CA3. The present findings should inform both theoretic and computational models of CA3 and CA1 function. © 2006 IBRO

A Face Versus Non-Face Context Influences Amygdala Responses to Masked Fearful Eye Whites

The structure of the mask stimulus is crucial in backward masking studies and we recently demonstrated such an effect when masking faces. Specifically, we showed that activity of the amygdala is increased to fearful facial expressions masked with neutral faces and decreased to fearful expressions masked with a pattern mask—but critically both masked conditions discriminated fearful expressions from happy expressions. Given this finding, we sought to test whether masked fearful eye whites would produce a similar profile of amygdala response in a face vs non-face context. During functional magnetic resonance imaging scanning sessions, 30 participants viewed fearful or happy eye whites masked with either neutral faces or pattern images. Results indicated amygdala activity was increased to fearful vs happy eye whites in the face mask condition, but decreased to fearful vs happy eye whites in the pattern mask condition—effectively replicating and expanding our previous report. Our data support the idea that the amygdala is responsive to fearful eye whites, but that the nature of this activity observed in a backward masking design depends on the mask stimulus

Etnobotânica e divergência genética de variedades de mandioca, Poconé, Mato Grosso.

A região denominada Baixada Cuiabana fica ao norte do Pantanal Mato-Grossense. É uma das poucas regiões do Mato Grosso que preserva as antigas características de comunidades de agricultores de subsistência que mantêm expressiva diversidade de mandioca (Manihot esculenta Crantz) e outros cultivos, visto a região ser centro de diversidade do gênero. Este estudo teve por objetivo caracterizar a diversidade genética de mandiocas mediante o conhecimento etnobotânico das variedades e marcadores microssatélites para compreender a dinâmica de conservação e manejo do acervo usado pelos agricultores da Comunidade São Benedito, Poconé, Mato Grosso. O presente trabalho foi autorizado pelo Conselho de Gestão do Patrimônio Genético (processo n. 02000.003025/2013-13-MMA deliberado em 28 de abril de 2015 e publicado no D.O.U em 13 de julho de 2015). Para o inventário etnobotânico foram aplicadas entrevistas semiestruturadas em 10 unidades domésticas para obter informações sobre as mandiocas cultivadas. Das 11 variedades locais cultivadas foi realizada análise por microssatélites (12 locus). Apesar da baixa diversidade etnobotânica encontrada (H?=2,05), foi encontrada alta heterozigosidade observada (Ho = 0,92) e diversidade gênica (He = 0,75). Os agricultores que sobrevivem basicamente do cultivo da mandioca e produção de farinha para comercialização, direcionam suas escolhas de variedades para as mais produtivas e menos suscetíveis ao ataque de pragas. A variedade brava foi a mais frequente (80% das roças) e é apontada como a mais rentável para a produção de farinha, sendo uma importante fonte de recurso genético para programas de melhoramento. Através da análise de rede pode-se observar que a rede de circulação de propágulos e informações ocorre entre os moradores e também com outras comunidades da região, importantes fontes de novas variedades. Dois agricultores foram identificados como os mais atuantes nas trocas. De acordo com o agrupamento e análise de coordenadas principais feitos utilizando os dados genéticos, as variedades introduzidas mais recentemente separam-se das introduzidas há mais tempo. As variedades apontadas como com alto teor de ácido cianídrico pelos agricultores também ficaram agrupadas. Notou-se que as variedades locais apresentam genes úteis para características importantes como, resistência a estresses bióticos e abióticos.Edição Especial dos Anais do 3 Simpósio da Rede de Recursos Genéticos Vegetais do Nordeste, Aracaju, out. 2017

Protein interactions with piALU RNA indicates putative participation of retroRNA in the cell cycle, DNA repair and chromatin assembly

Recent analyses suggest that transposable element-derived transcripts are processed to yield a variety of small RNA species that play critical functional roles in gene regulation and chromatin organization as well as genome stability and maintenance. Here we report a mass spectrometry analysis of an RNA-affinity complex isolation using a piRNA homologous sequence derived from Alu retrotransposal RNA. Our data point to potential roles for piALU RNAs in DNA repair, cell cycle and chromatin regulations

Influence of the use of manioc on its genetic diversity conservation in a quilombo community in Mato Grosso, Brazil.

Local cassava varieties play an important role in food security and the autonomy of subsistence farmers. They can be important resources for breeding and conservation programs. We examined the genetic diversity of cassava through ethnobotanical knowledge and microsatellite markers to understand the dynamics of conservation and management of the varieties used local small-scale farmers of a rural quilombo (a slave-descendant community) in Mato Grosso, Brazil. To obtain ethnobotanical information, semi-structured interviews were applied to 10 family units who cultivated cassava. Each family cultivated from one to five varieties, with 2.3 ± 1.16 varieties/farmer, on average. Genetic analysis was was made of the 11 local varieties with microsatellite markers (12 loci). Despite low ethnobotanical diversity (H' = 2.05), high genetic diversity was found (Na = 6.75, HO = 0.92, HE = 0.75, on average) in these local varieties. These farmers, who derive their income mainly from cassava cultivation and flour production for the market, direct their variety choices to those that are most productive. Brava variety was the most frequent (found in eight family units) and was considered the most profitable for the production of flour Network analysis showed that propagule circulation and information occurs between the residents and also with other communities of the region, which are important sources of new varieties. Two farmers were identified as the most active in this network, showing potential as key elements for the circulation of propagating material. According to the cluster analysis using the genetic data, the most recently introduced varieties (Baixinha, Liberatona, Broto roxo, Mansa, Ramo branco, Carneiro and Cuiabana) are separated from those introduced a long time ago. The varieties pointed out as bitter by the farmers were also grouped together. The results showed the importance of traditional farmers in maintaining a high genetic diversity of manioc varieties, despite the directing of the choice of varieties to meet market needs

Global selective sweep of a highly inbred genome of the cattle parasite Neospora caninum

Neospora caninum, a cyst-forming apicomplexan parasite, is a leading cause of neuromuscular diseases in dogs as well as fetal abortion in cattle worldwide. The importance of the domestic and sylvatic life cycles of Neospora, and the role of vertical transmission in the expansion and transmission of infection in cattle, is not sufficiently understood. To elucidate the population genomics of Neospora, we genotyped 50 isolates collected worldwide from a wide range of hosts using 19 linked and unlinked genetic markers. Phylogenetic analysis and genetic distance indices resolved a single genotype of N. caninum. Whole-genome sequencing of 7 isolates from 2 different continents identified high linkage disequilibrium, significant structural variation, but only limited polymorphism genome-wide, with only 5,766 biallelic single nucleotide polymorphisms (SNPs) total. Greater than half of these SNPs (∼3,000) clustered into 6 distinct haploblocks and each block possessed limited allelic diversity (with only 4 to 6 haplotypes resolved at each cluster). Importantly, the alleles at each haploblock had independently segregated across the strains sequenced, supporting a unisexual expansion model that is mosaic at 6 genomic blocks. Integrating seroprevalence data from African cattle, our data support a global selective sweep of a highly inbred livestock pathogen that originated within European dairy stock and expanded transcontinentally via unisexual mating and vertical transmission very recently, likely the result of human activities, including recurrent migration, domestication, and breed development of bovid and canid hosts within similar proximities