Physical Sciences and Mathematics Commons^™

Study Of Iron In Magnetotactic Bacteria, Richard B. Frankel, Richard P. Blakemore

Physics

Bacteria have recently been discovered directing their movements by sensing the earth's magnetic field. They contain arrays of crystals of lodestone or magnetite which they synthesize from iron in the ocean. The discovery of the same type of crystals in the abdomens of honey bees and the brains of homing pigeons suggests that nature is not oblivious to the earth's magnetic field. The biological mechanism for sensing magnetic fields has never been determined. These bacteria are capable of biologically synthesizing highly purified single domain magnets that would be very expensive to produce chemically.

The tiny perfect magnetite crystals made by …

Mossbauer Spectroscopy Of Iron-Containing Dermal Granules From Molpadia Intermedia, S. Ofer, G. C. Papaefthymiou, R. B. Frankel, H. A. Lowenstam

Physics

Dermal granules containing hydrous ferric oxide cores from Molpadia intermedia were studied by Mössbauer spectroscopy from 1.5 t0 300 K and in magnetic fields up to 80 kOersted at 4.2 K. A magnetic phase transition to an antiferromagnetically ordered state is observed at 10 K. The results are compared with the magnetic behavior of micellar cores of ferritin from eukaryotes and iron-storage materials from prokaryotes.

Bulk Magnetic Properties Of Magnetotactic Bacteria, C. R. Denham, R. P. Blakemore, Richard B. Frankel

Physics

Bulk magnetization measurements at room temperature of freeze dried magnetotactic bacterial cells, nonmagnetotactic bacterial cells, and extracted magnetosomes from magnetotactic cells are presented. The role of the magnetosome in the magnetotactic response of swimming cells is discussed.

South-Seeking Magnetotactic Bacteria In The Southern Hemisphere, R. P. Blakemore, Richard B. Frankel, Ad. J. Kalmijn

Physics

Several species of aquatic bacteria which orient in the Earth's magnetic field and swim along magnetic field lines in a preferred direction (magnetotaxis) have been observed in marine and freshwater sediments of the Northern Hemisphere^1,2. Their orientation is due to one or more intracytoplasmic chains of single-domain magnetite particles³. These linearly arranged particles impart a net magnetic dipole moment to the bacterium, parallel to the axis of motility. Northern Hemisphere magnetotactic bacteria with unidirectional motility swim consistently in the direction of the magnetic field, that is, to the geomagnetic North^1,2,4. This implies that their …

Nature Of Iron Deposits On The Cardiac Walls In Β-Thalassemia By Mössbauer Spectroscopy, K. S. Kaufman, G. C. Papaefthymiou, Richard B. Frankel, A. Rosenthal

Physics

An identification of the nature and an estimation of the particle size distribution of the iron deposits on thalassemic heart tissue is carried out by variable temperature Mössbauer spectroscopy. Comparison of Mössbauer spectra obtained for the thalassemic heart tissue (I) with those of normal heart tissue (II) and of horse spleen ferritin (III) identifies the iron deposits to be small, superparamagnetic particles of ferritin and/or hemosiderin, two closely related iron storage proteins containing an iron core of (FeOOH)₈(FeO · OPO₃H₂). The dependence of the superparamagnetic relaxation time, τ₂, of magnetically ordered fine …

An Empirical Bayes Approach To Polynomial Regression Under Order Restrictions, Leonard W. Deaton

Statistics

An unknown polynomial is to be estimated over a finite interval from N independent, normally distributed observations. A prior distribution is placed on the polynomial coefficients expressing the opinion that the coefficients decrease in absolute value as the degree of the corresponding terms increase. The data are used to estimate the parameters in the prior distribution of the coefficients. A Monte Carlo study is presented which compares the proposed method with the lack-of-fit procedure. This study indicates that the proposed method performs well in terms of minimizing a squared error loss as well as in yielding the correct degree of …

Asymptotic Numbers: Ii. Order Relation, Infinitesimals And Interval Topology, Todor D. Todorov

Mathematics

It has been shown in [8] that the set of asympototic numbers A is a system of generalized numbers including isomorphically the set of real numbers R, as well as the field of formal power (asymptotic) series. In the present paper, which is a continuation of [8], an order relation in A is introduced due to A turning out to be a totally-ordered set. The consistency between the order relation and the algebraic operations in A is investigated and in particular, it is shown that the inequalities in A can be added and multiplied as in the set of …

Asymptotic Numbers: I. Algebraic Properties, Todor D. Todorov

Mathematics

The set of asymptotic numbers A introduced in Refs. [1] and [3] is a system of generalized numbers including the system of real numbers R, as well as infinitely small (infinitesimals) and infinitely large numbers. The purpose of this paper is to study in detail the algebraic properties of A which are a little unusual, in a cenain sense, as compared with the known algebraic structures (rings. fields, etc.) This is necessary for the investigation of the class of asymptotic functions [2.4], which are on their part, generalized functions similar to the distributions of Schwartz but allowing the operation of …

Navigational Compass In Magnetic Bacteria, Richard B. Frankel, R. P. Blakemore

Physics

Magnetotactic bacteria that orient and swim in a preferred direction in the geomagnetic field contain sufficient single domain magnetite to constitute a biomagnetic compass.

Magnetic Properties Of [Fe4S4(Sr)4]3- Clusters, G. C. Papaefthymiou, Richard B. Frankel, S. Foner, E. J. Laskowski, R. H. Holm

Physics

No abstract provided.

Electronic Properties Of Molybdenum-Iron-Sulfur-Clusters: Approaches To The Molybdenum Site In Nitrogenase, Richard B. Frankel, T. E. Wolff, P. P. Power, R. H. Holm

Physics

No abstract provided.

Effect Of Magnetic Fields On Drug Induced Contractility And Mortality In Spirostomum, Angela Ripamonti, Richard B. Frankel, E. M. Ettienne

Physics

The influence of homogeneous magnetic fields up to 5.5 T on contractile frequency and mortality in the ciliate protozoan spirostomum ambiguum stimulated by 2,2′ PDS is reported. Magnetic fields are observed to decrease contractile frequency and to significantly increase mortality.

Magnetite In Freshwater Magnetotactic Bacteria, Richard B. Frankel, Richard P. Blakemore, Ralph S. Wolfe

Physics

A previously undescribed magnetotactic spirillum isolated from a freshwater swamp was mass cultured in the magnetic as well as the nonmagnetic state in chemically defined culture media. Results of Mössbauer spectroscopic analysis applied to whole cells identifies magnetite as a constituent of these magnetic bacteria.

Abstract: Fe Hyperfine Fields In Fe3 _ XVXSi Alloys, T. J. Burch, C. A. Weiler, K. Raj, J. I. Budnick, V. Niculescu, C. C. Papefthymiou, Richard B. Frankel

Physics

No abstract provided.

On The Existence Of Good Markov Strategies, Theodore P. Hill

Research Scholars in Residence

In contrast to the known fact that there are gambling problems based on a finite state space for which no stationary family of strategies is at all good, in every such problem there always exist ε-optimal Markov families (in which the strategy depends only on the current state and time) and also ε-optimal tracking families (in which the strategy depends only on the current state and the number of times that state has been previously visited). More generally, this result holds for all finite state gambling problems with a payoff which is shift and permutation invariant.

Distortion Isomerism In Ferrous Thiourea Complexes - Ii(1) Thermodynamics And Kinetics, R. Latorre, J. A. Costamagna, E. Frank, C. R. Abeledo, R. B. Frankel

Physics

Mössbauer spectroscopy as a function of temperature of Fe(II)(N,N′-dicyclohexyl-thiourea)₆(ClO₄)₂(FeDCTU) shows the existence of two isomeric forms A and B which coexist in the temperature range 200 < T < 300 K. The relative concentrations of A and B were studied as a function of time at different temperatures in the coexistence region. From the equilibrium constant as a function of temperature we obtain the following thermodynamic parameters: ΔH = −4520 ± 120 cal/mol and δS = 20 ± 0.1 e.u. The kinetics seem to follow an ordinary first order law but with an unusual temperature dependence of the rate constant k₁. The results are discussed in terms of hydrogen bonded interactions between the perchlorate anions and the cyclohexylthiourea moieties.

Ferromagnetism In Freshwater Bacteria, Richard P. Blakemore, Richard B. Frankel, Ralph S. Wolfe

Physics

Magnetotactic bacteria isolated from swamp water were grown in pure culture in the laboratory. This newly isolated species was cultured in the magnetic and the nonmagnetic state. Magnetic cells, which were rich in iron, also produced particles similar to those found previously in other magnetic bacteria of marshes and bogs. By contrast, their nonmagnetic counterparts had much lower iron levels and lacked the crystal structures. Mossbauer spectroscopic analyses of whole cells of magnetic bacteria indicated that they contained the mineral magnetite.

Second Leray Spectral Sequence Of Relative Hypercohomology, Saul Lubkin, Goro C. Kato

Mathematics

A second Leray spectral sequence of relative hypercohomology is constructed. (This is skew in generality to an earlier one constructed by S. Lubkin [(1968) Ann. Math. 87, 105-255].) The Mayer-Vietoris sequence of relative hypercohomology [Lubkin, S. (1968) Ann. Math. 87, 105-255] is also generalized.

Magnetic Properties Of Linear Chain Systems: Metamagnetism Of Single Crystal Co(Pyridine)2Cl2, S. Foner, Richard B. Frankel, W. M. Reiff, H. Wong, Gary J. Long

Physics

The metamagnetic behavior of the low temperature properties of single crystal Co(pyridine)₂Cl₂ is discussed. At 1.25 K oriented single crystals exhibit a two‐step metamagnetic transition at applied fields ∼0.8 and 1.6 kG along the b‐axis, a single transition at ∼0.7 kG for applied fields along the a^∗ axis, and a single transition at ∼4.2 kG for an applied field along the c axis. Just above the transition fields a moment of 2μ_B/Co atom is measured for B₀ parallel to the a^∗ axis or b axis, and 0.4μ_B/Co atom is …

Mössbauer Spectroscopy Of Iron Deposits In Thalassemic Heart Tissue, G. C. Papaefthymiou, K. S. Kaufman, Richard B. Frankel, A. Rosenthal

Physics

No abstract provided.

Critical Evaluation Of The Pulsed-Current Resistance Meter For Detection Of Decay In Wood, Douglas D. Piirto, W. Wayne Wilcox

Natural Resources Management and Environmental Sciences

An evaluation of a pulsed-current resistance meter ("Shigometer®", Model No. 7950) for facilitating detection of decay was performed on wood blocks of giant sequoia heartwood and of white fir sapwood. As decay progressed over a 12-week incubation period, a trend of lower meter readings was obtained, confirming reported field measurements of other workers. Variability in meter readings in situations where the range in resistance readings between sound and decayed wood is narrow (e.g., giant sequoia heartwood) and apparent inability of the meter to make readings necessary to diagnose decay at MCs common to wood in service without ground or water …

Mössbauer Study Of Spin Alignment In Substituted Lithium Ferrites, C. R. Abeledo, Richard B. Frankel

Physics

To explain the decrease of magnetic moment in zinc substituted lithium ferrites Dionne has proposed a model which includes canting of the B sublattice moments as zinc is substituted in the A sublattice. Mössbauer spectroscopy in external magnetic fields is applied to investigate the existence of canting in (Li₀,₅Fe₀, ₅)_1-xZn_xFe₂O₄ with x = 0 and x = 0.3. The samples used were either polycrystalline powders or circular disks cut from pressed blocks and lapped down to a thickness of 0.1 mm. In the x = 0 …

Poria Incrassata In Giant Sequoia, Douglas D. Piirto, John R. Parmeter, W. Wayne Wilcox

Natural Resources Management and Environmental Sciences

No abstract provided.

Lipschitz Spaces Of Distributions On The Surface Of Unit Sphere In Euclidean N-Space, Harvey Greenwald

Mathematics

In this paper Lipschitz spaces of distributions are defined and various inclusion relations are shown. Certain properties such as completeness, separability, and the density of the testing space for appropriate Lipschitz spaces are proved. The Littlewood-Paley function is defined and used to prove inclusion relationships between Lipschitz and Lebesgue spaces.

Excited States And Photochemistry Of Saturated Molecules, Patrick M. Saatzer, Robert D. Koob, Mark S. Gordon

Office of the Provost Scholarship

The molecular structures and bond energies in the low-lying excited states of n-alkanes from methane to n-pentane are investigated using the semi-empirical INDO method with configuration interaction. In general the calculated geometries and bond energies are consistent with the known threshold photochemistry of these molecules, the only exception being the prediction of vicinal (rather than geminal) elimination of H₂ in ethane. It appears that INDO overestimates the amount of angular distortion in these excited states.

Model Fe(Iii) Porphyrin Systems: Axial Ligation In Oxidized Cytochrome P-450.S, G. C. Papaefthymiou, Richard B. Frankel, S. Foner, S. C. Tang, S. Koch, R. H. Holm

Physics

In an effort to develop useful experimental criteria to distinguish among the viable axial ligation possibilities of O, N, and S coordination in oxidized cytochrome P-450. S (substrate-bound, high-spin), syntheticmodel compounds with O-(Fe(PPIXDME) (OEt) and Fe(PPIXDME) (OC₆H₄NO₂)) and S-(Fe(PPIXDME) (S₆H₄NO₂) and Fe(OEP) (SPh)) donor axial ligands were prepared and studied by Mössbauer spectroscopy. Ferric hemoglobin and myoglobin were used as model compounds with N-axial coordination. The isomer shifts (δ) and quadrupole splittings (ΔE_Q) observed are typical of high-spin Fe(III) porphyrins and are comparable with results …

Synthetic Analogs Of The Active Sites Of Oxidized And Reduced Rubredoxin, Richard B. Frankel, G. C. Papaefthymiou, R. W. Lane, R. H. Holm

Physics

The bischelate monoanion [Fe((SCH₂)₂C₆H₄)₂]^1- contains an unconstrained, near-tetrahedral Fe(III)-S₄ coordination unit (similar to the Fe-S₄ coordinationunit occurring in rubredoxin proteins) and exhibits the Fe(III)/Fe(II) redox couple. Mossbauer parameters at 77 K are isomer shift δ = 0.13 mm/s (relative to iron metal) and electric quadrupole splitting ΔE_Q = 0.57 mm/s. Application of an external magnetic field parallel to the direction of observation at 4.2 K induces a saturation magnetic hyperfine field of - 380 kOe. Upon reduction to the dianion [Fe((SCH₂)₂C …

Abstract: Mössbauer Spectroscopy Of Pdh Fe Alloys, M. Weber, C. R. Abeledo, Richard B. Frankel, Brian B. Schwartz

Physics

Large changes in the electron susceptibility of PdH alloys have been observed with increasing H concentration, with important consequences for the magnetic and superconducting properties of these alloys. (1) To observe the effect of the changing spin susceptibility, we have studied PdH Fe alloys with 2, 1 and < 0.1 at. % Fe by Mössbauer spectroscopy in external magnetic fields. Mydosh (2) has reported spin glass behavior in the high Fe concentration alloys and Kondo phenomena in the dilute Fe alloys. For hydrogen-metal ratios < 0.5, α and β phases, with low and high hydrogen content respectively, coexist. For temperatures below T_c of the α phase but above T_c of the β phase, we observe a superposition of a six line spectrum and a single line corresponding to the α and β phases respectively. (3) In an applied field, the β phase magnetizes and both phases have hyperfine fields which extrapolate to …

Mössbauer And Nmr Studies Of Site Substitution And Magnetic Structure Of Fe3-XMnXSi Alloys, K. Raj, V. Niculescu, T. J. Burch, J. I. Budnick, Richard B. Frankel

Physics

The NMR measurements in Fe_3−xMn_xSi alloys show increasingly complex spectra for x > 0.75 due to overlapping signals from Fe, Si and Mn nuclei in various sites. Mössbauer experiments were undertaken to identify the Fe⁵⁷ resonances. The combined NMR and Mössbauer results have been used to elucidate the site substitution and magnetic structure of these alloys for (0 < x < 1.75).

Metamagnetism In Single Crystal Γ-Co(Pyridine)2Cl2, S. Foner, Richard B. Frankel, W. M. Reiff, H. Wong, Gary J. Long

Physics

Small (≤1 mg) single crystals of γ-Co(pyr)₂Cl₂ have been grown and measurements of magnetic moment vs applied field H and temperature have been made for 0≤H≤54 kG and 1.25 K≤T≤4.2 K. At 1.25 K, metamagnetic transitions are observed along the a-axis at ~700 G; along the b-axis at both ~800 and ~1500 G; and along the c-axis at ~4 kG. The low field susceptibilities show a maximum at T≃3.4 K for each orientation. Magnetic saturation is not achieved at 54 kG; about 2.5 µ_B is achieved along the a*- or b-axes, whereas a lower moment is …