Interpretation Of Many Experiments Research Articles

The Great Power of Prediction from a Massive Photon Hypothesis.

Mass, an inherent property of matter, is calculated directly for the photon particle from the very classical principles of the kinetic theory of gases. That concept of photon mass is nearly as old as physics itself and in fact nothing prevents this approach to be carried out for a so-called quantum particle, not even its minute size. It is not an end result with no perspective nor other outcome. Quite the opposite, a single ponderable tiny photon frees the mind of old ways of thinking and opens up new paths to a broad field of investigation where the very large can then be described and explained by the very small. This reality of a non-zero mass suddenly shows up in the interpretation of many experiments which become clear and simple to comprehend. Besides, that same key particle has the potential to unlock and solve some long lasting major observational issues or enigmas. All this converges upon its acknowledgment and acceptance. Mass, an inherent property of matter, is calculated directly for the photon particle from the very classical principles of the kinetic theory of gases. That concept of photon mass is nearly as old as physics itself and in fact nothing prevents this approach to be carried out for a so-called quantum particle, not even its minute size. It is not an end result with no perspective nor other outcome. Quite the opposite, a single ponderable tiny photon frees the mind of old ways of thinking and opens up new paths to a broad field of investigation where the very large can then be described and explained by the very small. This reality of a non-zero mass suddenly shows up in the interpretation of many experiments which become clear and simple to comprehend. Besides, that same key particle has the potential to unlock and solve some long lasting major observational issues or enigmas. All this converges upon its acknowledgment and acceptance.

Nanoscale Light Confinement: the Q’s and V’s

Microcavities and nanoresonators have the ability to strongly enhance many light−matter-interaction processes used in various applications in nano-optics. This enhancement is due to the resonant excitation of an electromagnetic mode that confines light in space (mode volume) and in time (quality factor). The confinement is not perfect and the modes, even dark ones, always leak some energy and have a finite lifetime. Their non-Hermitian character does significantly more than merely broadening the resonances. In this Perspective, we clarify the main difference between bound modes of Hermitian systems and leaky modes of non-Hermitian resonators, emphasizing the key existence of a spatially dependent phase factor as a signature of nonhermiticity. For decades, the phase factor has often be considered as puzzling or has even be ignored, although it plays a key role in the interpretation of many experiments on nanoscale resonant-mediated light−matter interaction, such as sensing with cavity perturbation, modification of the spontaneous emission rate, optomechanics, strong coupling, and so on. The situation has changed recently, to a point that nowadays a sound non-Hermitian formalism has been developed and freeware packages exist, helping analyze experiments that continuously push back the extraordinary limit offered by large fields for exploring matter with light.

The effective temperature in microcanonical rate constants

Microcanonical rate constants can be parameterized in terms of an effective temperature. We show here that for fairly general level densities of the involved species it is possible to make this parametrization with a temperature-independent heat capacity and a rate constant of the Arrhenius form. This is a major simplification in the interpretation of many experiments on unimolecular decay in vacuum. The results show that activation energies and heat capacities measured in microcanonical experiment differ from their canonical analogues.

Diffuse ultrasonic backscatter at normal incidence through a curved interface

Diffuse ultrasonic backscatter techniques are useful for probing heterogeneous materials to extract microstructural parameters and detect flaws which cannot be detected by conventional ultrasonic techniques. Such experiments, usually done using a modified pulse-echo technique, utilize the spatial variance of the signals as a primary measure of microstructure. Quantitative ultrasonic scattering models include components of both transducer beams as well as microstructural scattering information. Of particular interest for interpretation of many experiments is the propagation through a liquid-solid interface. Here, a recent single-scattering model is expanded to include components needed for comparison with experiments. In particular, the Wigner distribution of the displacement profile is derived to model the beam pattern of an ultrasonic transducer through a curved liquid-solid interface. A simple Gaussian beam is used to model the transducer beam pattern. This expression is then used in conjunction with an appropriate scattering operator to complete the derivation. The theory developed is then compared with experimental results for a fine-grained steel using both a planar and a cylindrical interface. These results are anticipated to impact ultrasonic nondestructive evaluation and characterization of heterogeneous media with arbitrary curvatures.

Diffuse ultrasonic backscatter at oblique incidence for heterogeneous solids

Diffuse ultrasonic backscatter techniques are useful for probing heterogeneous materials. They can be used to extract microstructural parameters and to detect flaws which cannot be detected by conventional ultrasonic techniques. Such experiments, usually done using a modified pulse-echo technique, utilize the spatial variance of the signals as a primary measure of microstructure. Quantitative ultrasonic scattering models include components of both transducer beams as well as microstructural scattering information. Of particular interest for interpretation of many experiments is the propagation through a liquid-solid interface at normal and oblique incidence. Here, the Wigner distribution of the beam pattern of an ultrasonic transducer through a liquid-solid interface is used in conjunction with the stochastic wave equation to model this scattering problem within a single scattering formulism. The Wigner distribution represents a distribution in space and time of the spectral energy density as a function of wave vector and frequency. A Gaussian beam is used to model the transducer beam pattern. The scattered response in the time domain is then compared with experimental results for materials of common interest. These results are anticipated to impact ultrasonic nondestructive evaluation and characterization of heterogeneous media.

Wigner distribution of an ultrasonic transducer beam pattern through a liquid‐solid interface

Diffuse ultrasonic backscatter techniques are useful for probing heterogeneous materials to extract microstructural parameters and detect flaws that cannot be detected by conventional ultrasonic techniques. Such experiments, usually done using a modified pulse‐echo technique, utilize the spatial variance of the signals as a primary measure of microstructure. Quantitative ultrasonic scattering models include components of both transducer beams as well as microstructural scattering information. Of particular interest for interpretation of many experiments is the propagation through a liquid‐solid interface. Here, the Wigner distribution of the beam pattern of an ultrasonic transducer through a liquid‐solid interface is used in conjunction with the Bethe‐Salpeter equation to model this scattering problem. The Wigner distribution represents a distribution in space and time of the spectral energy density as a function of wave vector and frequency. The general scattering model to be discussed encompasses the full multiple scattering behavior that occurs within the solid, while a simple Gaussian beam is used to model the transducer beam pattern. A simplified model restricted to the single‐scattering regime is then compared with experimental results for materials of common interest. These results are anticipated to impact ultrasonic nondestructive evaluation and characterization of heterogeneous media.

Generation of turbulence by oscillating structures in superfluid helium at very low temperatures

The paper is concerned with the interpretation of many experiments that have been reported recently on the production of quantum turbulence by oscillating spheres, wires and grids in both 4He and 3He-B at temperatures so low that there is a negligible fraction of normal fluid. The experimental results are compared with those obtained in analogous experiments with classical fluids and with preliminary simulations of the quantum turbulence. Particular attention is paid to observed values of drag coefficients and to the very different critical velocities observed in 4He and 3He. It is tentatively concluded that in the case of 4He behaviour may well be similar to that observed in the classical analogues, with relatively small changes when the characteristic size of the oscillating structure is not large compared with the quantized vortex spacing, but that in the case of 3He behaviour is very different and due perhaps to very rapid intrinsic nucleation of the quantized vortices.

NUCLEAR-STRUCTURE THEORY IN THE SEARCH FOR NEW FUNDAMENTAL PHYSICS

Nuclear-structure theory is an important ingredient in the interpretation of many experiments that look for physics beyond the Standard Model. I review the role of nuclear structure in attempts to learn more about neutrinos through double beta-decay and to discover new sources of CP violation through atomic electric-dipole moments.

William Edward Caswell

William Edward Caswell

Intracellular sphingosine 1-phosphate production: a novel pathway for Ca2+release

Sphingolipids such as sphingosine 1-phosphate (SPP) and sphingosylphosphorylcholine have long been recognized to possess Ca2+mobilizing activity, yet to date little is known about their mechanism of action, or indeed their significance as Ca2+mobilizing intracellular messengers. The recent discovery of extracellular receptors for the sphingolipids has further complicated the interpretation of many experiments in this field. This paper reviews the current literature in which molecular and pharmacological approaches have begun to uncover the signalling components associated with intracellular SPP production and Ca2+mobilization. The functional significance of this novel Ca2+release pathway is also discussed.

The behavioral functions of the cholinergic basalforebrain : lessons from 192 IgG-SAPORIN

Until recently, our understanding of the functional neuroanatomy of the cholinergicbasal forebrain (CBF) has been hindered by the lack of a lesioning technique that is truly selective.The development of the immunotoxin 192 IgG-saporin (192-sap) has greatly improved our abilityto create specific lesions of the CBF. Rats with such lesions have been studied in a wide variety ofbehavioral paradigms of learning, memory, and attention. Complete or near-complete destructionof the CBF results in deficits in a variety of behavior paradigms including passive avoidance,spatial tasks (water and radial mazes), delayed matching to position/sample, and attentional tasks.However, interpretation of many experiments is hampered by incomplete lesions and/orconcomitant damage to cerebellar Purkinje neurons. Future studies will need to address theseissues. Recent development of a similar immunotoxin that is effective in primates should permitmore sophisticated behavioral analysis of CBF function. Additionally, immunotoxins selective forother types of neurons, such as the noradrenergic selective anti-DBH-saporin, will permit analysisof the behavioral functions of other diffusely projecting systems and how these other systems mayinteract with the CBF.

Dynamical current redistribution and non-Gaussian 1/f noise.

Dynamical current redistribution (DCR) in noisy resistors is discussed. Contrary to a common assumption in many theories and in the interpretation of many experiments, DCR can cause large-amplitude non-Gaussian (NG) noise for statistically independent fluctuators. NG effects are predicted to be large near the percolation threshold and near the metal-insulator transition. We report the first observations of NG noise in semiconductor superlattices and attribute this to DCR. We also show that DCR is the most likely explanation of NG noise in several other systems.

A note on the estimation of the chemical body composition of sows

Present day sows, particularly young sows, have smaller fat reserves than they did 10 to 20 years ago (Whittemore, Franklin and Pearce, 1980). Consequently, changes in the sows' body reserves during pregnancy and lactation have become much more critical in evaluating various nutritional strategies. The interpretation of many experiments designed ot investigate the effects of nutrition of the sow would be enhanced if changes in the body composition of the animal could be determined.

Self-Consistent Reduction of the Spitzer-Härm Electron Thermal Heat Flux in Steep Temperature Gradients in Laser-Produced Plasmas

A simple self-consistent limitation of the anisotropic portion of the local electron distribution function results in an order-of-magnitude reduction from the Spitzer-H\"arm thermal heat flux in steep temperature gradients, in agreement with recent Fokker-Planck simulations. A new upper bound derived for the local heat flux, substantially lower than that given by a "free-streaming" limit, accounts for most of the "inhibition" previously required in the interpretation of many experiments with high-power-laser-produced plasma.

Importance of new catecholamine pathways in control of blood pressure.

The first comprehensive maps of central catecholamine pathways referred to both noradrenaline and dopamine neurons. They described the catecholamine neurons as having their cell bodies in the brainstem with spinal axons descending mainly from two medullary cell groups (A1 and A2) and with ascending axons arising mainly from more rostral groups (A3-A13). More recent work utilising immunohistochemistry has established the presence of adrenaline neurons in the brain, in two medullary cell groups (C1 and C2). While these were originally thought to lie within the rostral part of the A1 and A2 cell groups, work from this laboratory has now established that the adrenaline neurons are topographically distinct from the A1 and A2 cells, do not fluoresce with standard methods, and are collected into three groups, the third group (C3) lying in the midline of the rostral medulla. Work in this laboratory using a combination of histochemical fluorescence and retrograde transport of horseradish peroxidase has demonstrated that existence of a descending dopaminergic projection from the hypothalamus to the spinal cord, indicating that descending pathways can arise well above the medulla. Recent studies on the A1 neurons have established the presence of projections from the A1 cells to the median eminence of the hypothalamus and towards the nucleus tractus solitarius in the medulla. Other experiments have demonstrated that most of the descending catecholamine axons do not arise from the A1 and A2 cell groups in the caudal medulla, but higher up in the brainstem especially from the A5 and A7 cell groups. These new descriptions of central catecholamine neurons will necessarily modify the interpretation of many experiments on the central regulation of arterial pressure.