Structures of a 10-subunit yeast RNA polymerase II have been derived from two crystal forms at 2.8 and 3.1 angstrom resolution. Comparison of the structures reveals a division of the polymerase into four mobile modules, including a clamp, shown previously to swing over the active center. In the 2.8 angstrom structure, the clamp is in an open state, allowing entry of straight promoter DNA for th...

A variety of mechanisms have been proposed for detecting inorganic ions using magnetic resonance imaging (MRI) contrast agents. In the most widely explored approach, analyte binding to a paramagnetic metal chelate withdraws ligand(s), increasing the number (q) of inner sphere sites available for water coordination at the paramagnetic center. As a consequence, the longitudinal relaxivity (r1) of...

In an effort to gain an understanding of the value of the information in different mass spectrometric measurements for protein identification, the genome of Saccharomyces cerevisiae was studied in silico. We calculate how constraining the knowledge of the mass of a proteolytic peptide is as a function of mass and mass accuracy. We also assess the value for protein identification of additional i...

the ingested nitrates sourced from tap water, food, chemicals and pharmaceuticals areconverted to nitrites in the body surfaces by bacteria and then, the nitrite ions can lead thestructural changing in hemoglobin. in the present work, aggregation of the purified hemoglobinin adult (hba) and in fetus or newborn (hbf) in the presence of nitrite ions were studied.hemoglobin aggregation was perform...

We quantified soil acidity and exchangeable cations in the forest floor and upper 7.5 cm of mineral soil beneath the canopies of individual trees of six different species in a mixed-species forest in northwestern Connecticut. Soil pH decreased in a sequence starting with sugar maple (Acer saccharum) . white ash (Fraxinus americana) . red maple (Acer rubrum) . beech (Fagus grandifolia) . red oak...

In soils of tropical climate regions the high acidity and the presence of exchangeable aluminum (Al), associated to low fertility, are the main restrainting factors for agricultural production. A laboratory experiment was conducted using 26 soils of different Brazilian regions, to investigate soil acidity components, giving emphasis to Al and their relations with chemical properties. The pH cor...

We introduce and study a class of exchangeable random graph ensembles. They can be used as statistical null models for empirical networks, and as a tool for theoretical investigations. We provide general theorems that characterize the degree distribution of the ensemble graphs, together with some features that are important for applications, such as subgraph distributions and kernel of the adja...

We investigate how to model exchangeability with choice functions. Exchangeability is a structural assessment on a sequence of uncertain variables. We show how such assessments are a special indifference assessment, and how that leads to a counterpart of de Finetti’s Representation Theorem, both in a finite and a countable context.

-The rates of release of AI by M NH~NO3 (pH 3) from minerals saturated with AI ions at pH 3 suggest that AI ions migrated from the surface layers and the matrix cores of kaolinite, montmorillonite, illite, and biotite, but only from the matrix core of muscovite mica. From the 0.25-0.5 p.m kaolinite and montmorillonite, part of the 'surface' A1 is released 'instantaneously' and the rest by first...