Johndale C. Solem

Microholography of living organisms.

By using intense pulsed coherent x-ray sources that are currently under development, it will be possible to obtain magnified three-dimensional images of elementary biological structures in the living state at precisely defined instants. For optimum contrast, sensitivity, and resolution, the hologram should be made with x-rays tuned to a resonance of nitrogen near 0.3 nanometer. Resolution will then be limited mainly by the hydrodynamic expansion that occurs while the necessary number of photons is being registered. Problems of technique are also briefly discussed.

Stable self-channeling of intense ultraviolet pulses in underdense plasma, producing channels exceeding 100 Rayleigh lengths

Spatially confined propagation of high-power subpicosecond (~270-fs) ultraviolet (248-nm) pulses has been experimentally studied in cold underdense plasma. The observed channels were longitudinally uniform, were approximately 1.4 μm in diameter, and persisted for a length of 3–4 mm, a distance exceeding 100 Rayleigh ranges. X rays with a quantum energy > 0.5 keV were also detected from the zone of propagation in coincidence with the channel formation. The occurrence of self-channeling with the rapid formation of a stable, extended, and longitudinally homogeneous filament is in qualitative agreement with a theoretical picture involving relativistic and charge-displacement nonlinearities.

X-Ray Biomicroholography

We discuss alternative techniques for microholography of biological specimens including requirements and constraints on the optical elements and recording media. We derive spatial and temporal coherence requirements for four representative holographic techniques and relate coherence and recording-medium resolution to maximum specimen volume. We give estimates of coherence length necessary to image a variety of specimens under a realistic set of assumptions. We discuss matters of wavelength selection with emphasis on the problem of obtaining high contrasts for nitrogen-bearing biological constituents. We use the eikonal approximation to derive equations for diffractive holographic imaging with particular attention to specimens of low contrast, and use these to illustrate the benefits of using 27r9 resonances to image molecular structures.

Dynamic polarization of protons and deuterons in solid deuterium hydride

Abstract Dynamic polarization of protons and deuterons in radiation-damaged solid deuterium hydride containing a small oxygen impurity and the parameters relating to this process have been investigated. The apparatus for preparing a sample from a gas mixture, for retaining it at liquid-helium temperature, for inflicting radiation damage, for observing its EPR and NMR spectra, and for measuring its nuclear- and electron-resonance relaxation times is described. The EPR spectra for atoms and radicals induced by radiation damage are displayed. The relaxation times of the H-atom resonances are shown to be greatly reduced when oxygen is added to the HD gas and a broad resonance appears, which is not present in purer samples and is ascribed to the radical Ȯ2D. The following data are presented for the most successful HD sample: (1) spin-lattice relaxation times for the proton, deuteron, and electron systems; (2) enhancement of proton polarization as a function of microwave power and magnetic field for microwave frequencies of 23.93 GHz and 35.68 GHz at temperatures of 4.2 K and ≈ 1.2 K; and (3) enhancement of deuteron polarization as a function of magnetic field for 23.93 GHz at 4.2 K and 1.3 K. A proton polarization of ≈ 3 3 4 % and a deuteron polarization of 0.3-0.4% have been obtained. Proton polarizations of more than 15% might be obtained if the field is raised to 25 kG and both H-atom resonances are used to drive transitions.

Solvable approximate model for the harmonic radiation from atoms subjected to oscillatory electric fields

We develop a nonperturbative model for the response of atomic electrons to oscillating external electric fields, valid in the physical regime where the central electric force is well described by an inverse square law and where the driven oscillations preserve the principal quantum number. We use the model to calculate the odd-harmonic electric-dipole radiation from a single atom driven by a laser field. The exact time-dependent eigensolutions of the model illustrate Zel’dovich’s concept of quasi-energy for sinusoidally time-dependent Hamiltonians. The validity and applicability of the model and suggested improvements are briefly discussed.

Understanding geometrical phases in quantum mechanics: An elementary example

We discuss an exact solution to the simplest nontrivial example of a geometrical phase in quantum mechanics. By means of this example: (1) we elucidate the fundamental distinction between rays and vectors in describing quantum mechanical states; (2) we show that superposition of quantal states is invalid; only decomposition is allowed—which is adequate for the measurement process. Our example also shows that the origin of singularities in the analog vector potential is to be found in the unavoidable breaking of projective symmetry caused by using the Schrödinger equation.

LASER COUPLING TO NUCLEI VIA COLLECTIVE ELECTRONIC OSCILLATIONS—A SIMPLE HEURISTIC MODEL STUDY

Abstract The induction field coupling of laser-driven collective electronic oscillations has been proposed as an interlevel transfer mechanism for a gamma-ray laser. Using a heuristic classical model for the electron oscillations, we verify in the model six general features which we conjecture are valid for laser-induced collective oscillations: (1) enhancement of the electric field seen by the nucleus, (2) harmonic generation, (3) generation of higher multipoles, (4) odd (even) order multipoles couple to odd (even) harmonics, (5) there exists an optimum laser intensity for each multipole order and harmonic, and (6) for a given multipole order, the optimum intensity increases with harmonic number. We briefly discuss the relevance of these results to a proposed interlevel transfer experiment in 235U.

A quantum-mechanical treatment of Szilard's engine: Implications for the entropy of information

We present a quantum-mechanical analysis of Szilards famous single-molecule engine, showing that it is analogous to the double-slit experiment. We further show that the energy derived from the engines operation is provided by the act of observing the molecules location. The engine can be operated with no increase in physical entropy, and the second law of thermodynamics does not compel us to relate physical entropy to informational entropy. We conclude that information per seis a subjective, idealized, concept separated from the physical realm. Physical entropy depends on physical objects and physical interactions, and any entropy change owing to observations is entirely a result of the entropy created in the physical apparatus by the process of observation.

An Astrophysical Basis For A Universal Origin Of Life

We propose a universal, astrophysically based theory of the origin of life on Earth and on other rocky planets as well. Life is an information system where the information content grows because of selection. It must start with the minimum possible information, or the minimum possible departure from thermodynamic equilibrium. It also requires thermodynamically free energy that is accessible by means of its information content. Hence, for its origin, we look for the most benign circumstance or minimum entropy variations over long times with abundant free energy. The unique location for this condition is the pore space in the first few kilometers of the earths surface. The free energy is derived from the condensed products of the chemical reactions taking place in the cooling nebula e.g. iron oxides and fixed hydrocarbon, (CH2)16 and the benign environment is the thermal and radiation isolation of the earths crust. We discuss how this environment occurs naturally and universally astrophysically. We then propose several chemical routes to the formation of life with a minimum entropy departure from thermodynamic equilibrium.

Self-assembling micrites based on the Platonic solids

Abstract Micrites capable of assembling into arbitrary shapes in three dimensions, with the constraint of a single species, might be most effectively fabricated in the shape of Platonic solids (regular polyhedra), to take advantage of maximum symmetry and to ensure that each polygon face of one micrite will perfectly coincide with the face of another micrite, thereby maximizing adhesion and minimizing stray fields. Only two of the regular polyhedra can be assembled to fill all space: the cube and the dodecahedron. Therefore, only the cube and dodecahedron are capable of constructing arbitrary shapes including the highest possible strength realized by a voidless solid. The dihedral angle between the adjoining faces of two cubes, joined by coinciding squares on a face of each cube, is 180 ° . Hence, it is difficult for an electric field, generated by charges on the perpendicular faces, to rotate the two cubes in such a way as to join at another pair of faces. The dodecahedron, however, has a corresponding dihedral angle of about 127 ° and a pair of dodecahedra can be easily caused to roll from one contact face to another. Therefore, the dodecahedron is the only space-filling Platonic solid that is also capable of easily-generated face-field-driven motion. I demonstrate that the micrites must be maintained in a fluid environment in order to provide sufficient lubrication for their polygonal binding surfaces to azimuthally rotate into coincidence. I calculate the speed of convergence in a lubricant environment and show that the distant micrites assemble only very slowly (for a practical range of parameters) unless there is some agitation of the fluid. I show how various solids can be constructed by convergence. I demonstrate how a primitive motor can be built from two dodecahedron-shaped micrites, and I calculate the maximum speed of the motor and the maximum power the motor can generate. I explain a surprisingly simple algorithm for a curious self-propelling flagellum constructed from a chain of dodecahedron-shaped micrites. I calculate the flagellum’s maximum swimming speed and power consumption.