Physical Sciences and Mathematics Commons^™

A Birefringence Relaxation Determination Of Rotational Diffusion Of Magnetotactic Bacteria, Charles Rosenblatt, Richard B. Frankel, Richard P. Blakemore

Physics

The orientational relaxation of the magnetotactic bacterium Aquaspirillum magnetotacticum is observed by the decay of the optical birefringence upon switching off an aligning magnetic field. The data yield a rotational diffusion constant D_r ≅ 0.13 s¹ and information about cell sizes that is consistent with optical microscopy data.

Mossbauer Spectroscopy Of Iron Biomineralization Products In Magnetotactic Bacteria, Richard B. Frankel, Georgia C. Papaefthymiou, Richard P. Blakemore

Physics

No abstract provided.

Asymptotic Functions As Kernels Of The Schwartz Distributions, Todor D. Todorov

Mathematics

Using a version of the sequential method we introduce a class of generalized functions called here "asymptotic functions''. This class contains kernels of all Schwartz distributions and is equipped with a correctly defined multiplication operation. So, in a sense, one solves the problem of "multiplication of Schwartz distributions" although the solution refers to the class of the asymptotic functions and not to the Schwartz distributions themselves. The paper is a continuation of a series of works [1-10] but here only part of the results of [5], [6] and [8] will be needed.

On The Notion Of Precohomology, Goro Kato

Mathematics

ABSTRACT. For a cochain complex one can have the cohomology functor. In this paper we introduce the notion of precohomology for a cochain that is not a complex, i. e., d^q+1 o d^q may not be zero. Such a cochain, with objects and morphisms of an abelian category A, is called a cochain precomplex whose category is denoted by Pco (A). If a cochain precomplex is actually a cochain complex, then the notion of precohomology coincides with that of cohomology, i. e., precohomology is a gene¬ralization of cohomology. For a left exact functor F from an abelian category …

The Products Δn2(X), Δ(X). X-N, ϴ(X). X-N, Etc. In The Class Of The Asymptotic Functions, Todor D. Todorov

Mathematics

Several products like δⁿ(x), δ(x)ϴ(x), δ^(m)(x). X^-n, ϴ(x). X^-n, etc., where δ(x), ϴ(x), X^-n, etc., are kernels of the corresponding Schwartz distributions, are studied in the framework of the class of the asymptotic functions F₀ introduced in a previous paper [11]. In some particular cases many formulae are derived and several examples are presented. The work is of mathematical type but its motivations lie in some problems in quantum theory. It is closely …

Soil-Saprolite Profiles Derived From Mafic Rocks In The North Carolina Piedmont: I. Chemical, Morphological, And Mineralogical Characteristics And Transformations, T. J. Rice, S. W. Buol, S. B. Weed

Earth and Soil Sciences

The chemical, morphological and mineralogical properties of two Enon sandy loam (fine, mixed, thermic Ultic Hapludalfs) soilsaprolite profiles, one formed on gabbro and the other on metagabbro, are compared. Clay skins are scarce and stress cutans common in the argillic horizons of these soils. Iron-manganese concretions are concentrated in soil horizons immediately above the argillic horizons. The high shrink-swell capacities and slow permeabilities of the argillic horizons result in relatively shallow depths to paralithic contact with saprolite. The parent rock from the Enon profile near Albemarle, Stanly County, North Carolina is a medium-grained metagabbro with chlorite, hornblende, quartz, and calcic …

Soil-Saprolite Profiles Derived From Mafic Rocks In The North Carolina Piedmont: Ii. Association Of Free Iron Oxides With Soils And Clays, T. J. Rice, S. B. Weed, S. W. Buol

Earth and Soil Sciences

The association of free Fe oxides with soils and clays from two Enon sandy loam (Ultic Hapludalfs, fine, mixed, thermic) soilsaprolite profiles was studied. Goethite was the dominant Fe oxide identified. Lepidocrocite was detected in trace amounts in some samples. FeCBD/clay ratios were highest in the epipedons of these soils suggesting the concentrating of Fe oxides as a result of aluminosilicate mineral weathering. External (BET-N2) surface area measurements of non-deferrated and deferrated clays were analyzed in conjunction with electron micrographs of selected clay fractions to determine the association of free Fe oxides with aluminosilicate clays as a function of depth …

Advances In Verification Technology, David W. Hafemeister

Physics

The alleged limits of verification techniques have been used to justify lack of action at the negotiating table, but advances in computer science and optics should help dispel doubts about the verifiability of treaties

Microaerobic Conditions Are Required For Magnetite Formation Within Aquaspirillum Magnetotacticum, R. P. Blakemore, K. A. Short, D. A. Bazylinski, Charles Rosenblatt, Richard B. Frankel

Physics

The amount of magnetite (Fe₃O₄) within magnetosomes of the microaerophilic bacterium Aquaspirillum magnetotacticum varies with oxygen and nitrogen supply. The development of optical methods for directly measuring cell magnetism in culture samples has enabled us to quantitate bacterial Fe₃O₄ yields. We measured final cell yields, average cell magnetic moments, and magnetosome yields of growing cells. Cultures were grown with NO₃^-, NH₄⁺, or both, in sealed, unshaken vials with initial headspace Po₂ values ranging from 0 (trace) to 21 kPa.

More than 50% of cells had detectable …

Statement Of Dr. David Hafemeister Regarding The Need To Convert Domestic Research Reactors From Highly Enriched To Low-Enriched Uranium Fuels, David W. Hafemeister

Physics

No abstract provided.

Structure, Morphology And Crystal Growth Of Bacterial Magnetite, Stephen Mann, Richard B. Frankel, Richard P. Blakemore

Physics

Recent high-resolution transmission electron microscopy (HRTEM) studies of the structure and morphology of bacterial magnetite (Fe₃O₄) crystals isolated from a magnetotactic coccus¹ and from an unidentified bacterium extracted from sediment² have shown the crystals to be well ordered single-domain particles with a morphology based on a hexagonal prism of {011} faces truncated by specific low index planes. We report here a HRTEM study of intact magnetite crystals (magnetosomes) in the microaerophilic bacterium Aquaspirillum magnetotacticum, grown in pure culture^3,4. Our aim has been to investigate the structure, morphology and crystal growth of …

On Maximizing The Average Time At A Goal, S. Demko, Theodore P. Hill

Research Scholars in Residence

In a decision process (gambling or dynamic programming problem) with finite state space and arbitrary decision sets (gambles or actions), there is always available a Markov strategy which uniformly (nearly) maximizes the average time spent at a goal. If the decision sets are closed, there is even a stationary strategy with the same property.Examples are given to show that approximations by discounted or finite horizon payoffs are not useful for the general average reward problem.

Magnetosome Dynamics In Magnetotactic Bacteria, S. Ofer, I. Nowik, E. R. Bauminger, G. C. Papaefthymiou, Richard B. Frankel, Richad P. Blakemore

Physics

Diffusive motions of the magnetosomes (enveloped Fe₃O₄ particles) in the magnetotactic bacterium Aquaspirillum magnetotacticum result in a very broad-line Mössbauer spectrum (T ~ 100 mm/s) above freezing temperatures. The line width increases with increasing temperature. The data are analyzed using a bounded diffusion model to yield the rotational and translational motions of the magnetosomes as well as the effective viscosity of the material surrounding the magnetosomes. The results are <θ²>^l/2 < 1.5° and <x²>^1/2 < 8.4 Å for the rotational and translational motions, respectively, implying that the particles are fixed in whole cells. The effective viscosity is 10 cP at 295 K and increases with decreasing temperature. Additional Fe³⁺ material in the cell is shown to be associated with the magnetosomes. Fe²⁺ material in the cell appears to be …

Magnetic Guidance Of Organisms, Richard B. Frankel

Physics

No abstract provided.

Basidiomycete Fungi Reported On Living Or Dead Giant Sequoia Or Coast Redwood, Douglas D. Piirto, John R. Parmeter, Jr., W. Wayne Wilcox

Natural Resources Management and Environmental Sciences

No abstract provided.

Precipitation Of Fe3O4 In Magnetotactic Bacteria, Richard B. Frankel, Richard P. Blakemore

Physics

The magnetotactic bacterium A. magnetotacticum contains ferrous ions, a low density hydrous ferric oxide, a high density hydrous ferric oxide (ferrihydrite) and Fe₃O₄, which is precipitated by partial reduction of the ferrihydrite precursor.

Hydrogeochemical Aspects Of Surface Mine Reclamation In The Northern Great Plains, Gerald H. Groenewold, Robert D. Koob

Office of the Provost Scholarship

Studies of several coal-mining sites in western North Dakota have resulted in the development of a hydrogeochemical model which accounts for the observed chemical characteristics of subsurface water in undisturbed settings. Critical hydrogeochemical processes include sulfide oxidation, gypsum precipitation and dissolution, carbonate mineral dissolution and cation exchange.

In the semi-arid climate of western North Dakota, the near-surface several meters of the landscape is constantly subjected to alternate wetting/drying. This mechanism is the key to hydrogeochemical evolution of both pore water in the rooting zone and subsurface water that eventually reaches the water table.

Recent refinements in the hydrogeochemical model have …

Causes Of Uprooting And Breakage Of Specimen Giant Sequoia Trees, Douglas D. Piirto, W. Wayne Wilcox, John R. Parmeter, Jr., David L. Wood

Natural Resources Management and Environmental Sciences

A study of the causes of uprooting and stem failure in old-growth giant sequoia (Sequoia gigantea [Lindl.] Decne) indicated many factors, depending upon the type of failure (by root, stem, or earth). Advanced decay and fire scars were the most frequently associated with failure. In 21 of 33 study trees, one-third or more of the roots were judged too decayed to provide support. Twenty-seven study trees possessed basal fire scars, and 26 fell toward the scarred side. Nine Basidiomycetes, including Fomes annosus, Poria albipellucida, Poria incrassata, and Armillaria mellea, were associated with decayed wood. Carpenter ants were found …

Enumeration Of Permutations By Descents, Idescents, Imajor Index, And Basic Components, Don Rawlings

Mathematics

Multivariable extensions of classic permutation cycle structure results are obtained by counting permutations by descents, idescents, imajor index, and basic components.

Biomineralizationof Fe3O4 In Bacteria, R. B. Frankel, G. C. Papaefthymiou

Physics

No abstract provided.

The Feasibility Of The X-Ray Laser Pumped With A Nuclear Explosion, David W. Hafemeister

Physics

Recent reports have indicated that an x-ray laser pumped with a nuclear explosion at a wavelength of 1.4nm (0.9 keV) has made some initial progress. It has been proposed to extend the development of this device to establish it as part of a layered ballistic missile defensive system to protect the United States against a nuclear attack. This paper will discuss the following aspects on the feasibility of this system: (1) Conditions affecting the efficiency of the X-ray laser; (2) Angular resolution and size of.the laser rods; (3) Energy on targets; (4) Basing Modes; (5) Countermeasures; and (6) Legal constraints.

Almost Sure Stability Of Partial Sums Of Uniformly Bounded Random Variables, Theodore P. Hill

Research Scholars in Residence

Suppose a₁ , a₂ ,... is a sequence of real numbers with a_n → ∞. If lim sup(X₁+ ... + X_n)/a_n = α a.s. for every sequence of independent nonnegative uniformly bounded random variables X₁,X₂,... satisfying some hypothesis condition A, then for every (arbitrarily-dependent) sequence of nonnegative uniformly bounded random variables Y₁,Y₂, ... , lim sup(Y₁+ ... + Y_n)/a_n = α a.s. on the set where the conditional distributions (given the past) satisfy …

Magnetic Phase Transition, Aggregate Formation, And Electrical Conductivity In Fecl3-Doped Polyacetylene, E. K. Sichel, M. F. Rubner, J. Georger, Jr., G. C. Papaefthymiou, S. Offer, Richard B. Frankel

Physics

Both Fe³⁺ and Fe²⁺ ions occur in FeCl₃-doped polyacetylene. At low dopant levels (2+ and Fe³⁺ ions are paramagnetic down to 4.2 K. At dopant levels >0.01 mole fraction, there is evidence from Mössbauer spectroscopy that Fe²⁺ ions associate into aggregates which are magnetically ordered below 25 K. Aggregate formation appears to correlate with high electrical conductivity.

The Combinatorics Of Certain Products, Don Rawlings

Mathematics

A combinatorial interpretation for the coefficients in the expansion of Π(1 + ux^jy^k)(1 - ux^jy^k)^-1 is given.

Fe3O4 Precipitation In Magnetotactic Bacteria, Richard B. Frankel, Georgia C. Papaefthymiou, Richard P. Blakemore, Wendy O'Brien

Physics

Using Mössbauer resonance spectroscopy of ⁵⁷Fe, we have determined the nature and distribution of major iron compounds in the magnetotactic bacterium Aquaspirillum magnetotacticum. In addition to magnetite (Fe₃O₄), cells contained a low-density hydrous ferric oxide, a high-density hydrous ferric oxide (ferrihydrite), and ferrous iron. Analysis at different temperatures of whole cells harvested early and late in growth, of mutant cells unable to synthesize magnetite, and of cell fractions enriched in ⁵⁷Fe indicated that Fe₃O₄ precipitation resulted from partial reduction of the high-density hydrous ferric oxide precursor.

Determining A Fair Border, Theodore P. Hill

Research Scholars in Residence

In a general class of measure-partitioning or fair-division problems, the extremal case occurs when the measures are proportional. Applications are given to classical and recent fair-division problems, and to statistical decision theory.

On The Generators Of The First Homology With Compact Supports Of The Weierstrass Family In Characteristic Zero, Goro Kato

Mathematics

No abstract provided.

A Stronger Form Of The Borel-Cantelli Lemma, Theodore P. Hill

Research Scholars in Residence

No abstract provided.

Stop Rule Inequalities For Uniformly Bounded Sequences Of Random Variables, Theodore P. Hill, Robert P. Kertz

Research Scholars in Residence

If X₀, X₁, ... is an arbitrarily-dependent sequence of random variables taking values in [0,1] and if V( X₀, X₁, ...) is the supremum, over stop rules t, of EX_f, then the set of ordered pairs {(x , y): x = V( X₀, X₁, ..., X_n and y = E(max_{jXj for some X0, ... , Xn} is precisely the set Cn = {(x, y): x < y < x(1 + n …}

The Advantage Of Using Non-Measurable Stop Rules, Theodore P. Hill, Victor C. Prestien

Research Scholars in Residence

Comparisons are made between the expected returns using measurable and non-measurable stop rules in discrete-time stopping problems. In the independent case, a natural sufficient condition ("preservation of independence") is found for the expected return of every bounded non-measurable stopping function to be equal to that of a measurable one, and for that of every unbounded non-measurable stopping function to be arbitrarily close to that of a measurable one. For non-negative and for uniformly-bounded independent random variables, universal sharp bounds are found for the advantage of using non-measurable stopping functions over using measurable ones. Partial results for the dependent case are …