bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Meteoric Dust on the Effective Recombination Coefficient in the Lower Ionosphere
Authors: Parthasarathy R. , Rai D. B. 
Published: November 2015

The effect of meteoric dust particles on the steady‐state distribution of electrons and ions in the lower ionosphere (50‐90 km) has been investigated. A formal expression for the effective recombination coefficient has also been derived, containing the terms for the rates of capture of electrons and positive and negative ions by the dust. These capture rates are derived by an extension of Natanson's theory of aerosol charging by the capture of ions. The altitude dependence of these coefficients is mainly determined by the altitude distribution of the dust concentration. It is found that only particles with radii larger than about a tenth of a micron play a significant role.The numerical values of the effective recombination coefficient for several altitudes in the D region have been compared with the values empirically determined by us from multiple‐frequency radiowave absorption data in the auroral zone, and found to be in satisfactory argeement. It is also shown that the role of dust concentration in the D region is of major significance when the ionization density is weak to moderate. For a strongly ionized D region, the role is significant only if the dust concentration is higher than is currently believed probable.
Some Problems Associated With Midlatitude Sporadic E
Authors: Cole Keith D. , Norton Richard B. 
Published: November 2015

There are many problems yet to be resolved in this field.If it is assumed that the major ions in sporadic E are NO+ and O+, then ionospheric studies and laboratory measurements suggest an appropriate value of α (the recombination coefficient) to be of order 10−7 cm3 sec−1 at room temperatures. This conflicts with the highest value of α tolerable to wind‐shear theory of about 3 × 10−8 cm3 sec−1. High electron temperatures in sporadic E clouds may reduce this discrepancy if a decreases with increase of temperature. In its present stage of development the windshear theory does not account for the high electron temperatures sometimes observed in association with sporadic E, nor does it account for the magnetic variation observed in association with sporadic E clouds.The possibility of an airglow component caused by recombination in sporadic E clouds is discussed.We conclude that measurements of ion composition, electron temperature, electric current, and VLF noise in sporadic E clouds should provide valuable clues in the further understanding of the phenomenon.
On the Point of Emergence of a Conical Microwave Beam Entering a Particular Nonuniform Plasma Column
Authors: Cullen A. L. 
Published: November 2015

A circularly symmetrical conical wave, in which E., is the only component of the electric vector, is incident upon a circularly symmetrical plasma column of radius a in which the electron density is proportional to (a2/r2)‐1 for a radial distance r≤a, and is zero for r>a. The change in phase on reflection is determined as a function of the angle of incidence. A circularly symmetrical beam of radiation can be synthesized as an angular spectrum of conical waves, and the corresponding reflected beam is easily obtained in integral form. The position of maximum intensity in the reflected beam is found by making use of the principle of stationary phase.The results obtained are compared with ray theory and with a previous calculation for a linear gradient of electron density in a planar geometry.
Analysis of a Double Discontinuity in a Coaxial Line
Authors: Hinchey F. A. , Prasad Sheila 
Published: November 2015

This paper presents a field analysis of two closely spaced abrupt discontinuities in a coaxial transmission line. The discontinuities occur in the radius of the inner conductor of the transmission line.The problem is formulated in terms of two simultaneous integral equations whose solution is obtained by a variational technique. The solution for the admittance is expressed in terms of an infinite series of field modes.The first 11 mode amplitudes have been obtained numerically for different dielectrics and different radii, and admittances calculated. A comparison is made with the results obtained from a transmission‐line theory approximation.
Quantitative Observations of Dot Angel Echoes at Two Frequencies
Authors: Deam Andrew P. , LaGrone Alfred H. 
Published: November 2015

Results of many observations of radar echoes of the clear‐air dot angel type at Austin, Tex., are reported. Measurements were made at two wavelengths, $#x03BB;=3.3 em and $#x03BB;=9.1 em, using nearly identical antenna beams pointed vertically. Results suggest particulate matter, probably insects, as the source of most clear‐air dot angel echoes.Other clear‐air angel‐type echoes which were observed on rare occasions are believed to originate at inversion layers. They were received only on S‐band and did not exhibit the same characteristics as most echoes of the dot angel type.
Numerical Solution of Full‐Wave Equation With Mode Coupling
Authors: Inoue Yuji , Horowitz Samuel 
Published: November 2015

A new method for the numerical solution of the wave equation governing the propagation of electromagnetic waves in a horizontally stratified, inhomogeneous, anisotropic medium is described. The wave equation is a homogeneous set of four linear differential equations of the first order. Four linearly independent solutions are derived.The medium is divided into a number of thin horizontal subslabs. Within a subslab, the propagation coefficient matrix is assumed to vary linearly with respect to height. Under this assumption, the modification of solutions from one height to another is expressed in power‐series form, and the inhomogeneity effect in a subs lab is examined. This, together with the extraction of the phase memory integral from the solution, allows an increase in the integration step size by a factor of 10 over that traditionally used.During an ordinary integration for an inhomogeneous medium a degradation occurs in the degree of linear independence among special solutions. This cause is analyzed. To obtain a complete set of special solutions with good linear independence, a technique is developed suitable for general application.This method has been programmed for computer calculation. The resultant wave fields and wave polarizations for the independent modes are shown for a model ionosphere. The resultant wave is described as a “scrambling” of four characteristic waves. The “scrambling” state is illustrated at each height.
Modal Solution of a Point Source in a Strongly Focusing Medium
Authors: Kornhauser and A. D. Yaghjian E. T. 
Published: November 2015

The ray solution for a point source located in a medium with varying propagation constant given by k(z) = h0 √sech2 αz β2 exhibits for β = 0 the interesting property of the focusing of all rays at periodic distances. The problem of finding the exact solution for the electromagnetic field reduces to that of finding Green's function to the scalar wave equation,∇G + k20 (sech2 αz − β)G = (1/2πr)δ(r)δ(z − z0).The eigenfunctions for this equation consist of a mixed spectrum, i.e., a continuous set of eigenfunctions plus a finite number of discrete eigenfunctions. The mixed spectrum is normalized and shown to form a complete set, in which the Green's function is expanded. Examination ofthe discrete spectrum in the far field reveals that all the lower order modes add in phase where ray theory predicts focusing. Integral approximations for the continuous spectrum show that it represents a nonpropagating, rapidly decaying field, which is negligible compared to the discrete spectrum, except in the region “close” to the point source.
Ionospheric Wave Theory Using Coupled Vacuum Modes
Authors: Poeverlein H. 
Published: November 2015

In coupled‐mode theory the wave field in a stratified anisotropic medium appears decomposed into modes, which are coupled in accordance with a set of coupled wave equations. The modes can be defined in various ways. In the conventional formulation they correspond to waves in a homogeneous magnetoionic medium; the present theory uses modes of vacuum propagation characteristics. The coupled wave equations for these vacuum modes have a fairly simple form. The effect of the medium appears in the coupling matrix, whose elements contain a number of terms depending on the various parameters of the medium.The coupled wave equations, originally obtained from a study of partial reflection at differential slabs of the medium, are now derived in two different ways, both rather direct. In one derivation the vector potential is split into ascending and descending parts. The other derivation adheres to the matrix formalism of the conventional coupling theory as far as possible, thus indicating the essential deviations from the conventional theory. The vertical energy flux densities of the modes are expressed in terms of the field quantities used.
Mode Matching Method for Anisotropic Guides
Authors: Mittra R. , Lee S. W. 
Published: November 2015

The mode matching technique is employed frequently in formulating discontinuity problems in isotropic waveguides. An example of this procedure appears in the work of Hurd and Gruenberg who have solved the problem of a bifurcated waveguide. They derive two doubly infinite sets of equations by using the continuity of the interface electrical and magnetic fields, respectively. The final equation for the large waveguide mode coefficients is obtained by subsequent elimination of the unknown mode coefficients of the smaller guides from the first two sets. A key step in this two‐step method of formulation involves the Fourier analysis of the fields using orthogonal mode functions as the basis. In the anisotropic version of the same problem, which is considered in this paper, it is observed that the conventional procedure does not lead to a convenient form. This is a consequence of the fact that the anisotropic guide modes are no longer orthogonal. It is shown that by using biorthogonality relationships introduced by Bresler and others, it is possible to derive a set of equations in the desirable form for the anisotropic case as well.An interesting observation about the procedure is that the matching of interface tangential electric and magnetic fields is carried out in a simultaneous manner, and hence, the final equations are obtained in a one‐step process as opposed to the two‐step procedure conventionally followed in the isotropic case. The paper discusses the solution of the infinite set of equations appropriate to the anisotropic case and compares it with the Wiener‐Hopf solution derived elsewhere.
Propagation of Hydromagnetic Waves in Current‐Carrying Regions of the Ionosphere and Magnetosphere (Parallel Propagation)
Authors: Abbas M. , Poeverlein H. 
Published: November 2015

Propagation of hydromagnetic waves in the presence of a constant current density is investigated. The theory is developed from macroscopic equations in which a constant current density is introduced by assuming streaming velocities of the electron and ion fluids. The general dispersion relation is derived, and approximate solutions of the dispersion relation are obtained for special situations.The special cases of this paper refer to a propagation vector in the direction of the magnetic field (“parallel propagation”). In parallel propagation, a transverse current density leaves the propagation vector unaffected, but causes a longitudinal electric field component and a consequent change of the ray direction. With the propagation vector and the current density in the magnetic field direction the effect of currents is significant when J0/H0 is of the order of k ≃ ω/Va (with H0 = B0/µ0 and Va as the Alfvém velocity). When the quantity J0/H0 is larger than the wave number k, the current densities lead to a nonconvective instability. A numerical evaluation demonstrates the effect that currents in the ionosphere and magnetosphere may have on the waves.
Ray Tracing in the lonosphere
Authors: Kelso John M 
Published: November 2015

The problems of tracing rays in the ionosphere for radio propagation, primarily for high frequencies (3 to 30 MHz) and above, are discussed. The limitations on “classical” geometrical optics are described, and their applications to ionospheric problems are indicated.Some “simplified” processes of ray tracing, which apply well at the earth's surface, but not in the ionosphere itself, are first presented. Next, ray‐tracing methods which apply in an isotropic ionosphere, when the effects of the earth's magnetic field is negligible, are discussed. The results are then extended to more general cases of an isotropic medium, and, finally, to an anisotropic medium (such as the ionosphere in the presence of the earth's magnetic field).Certain special problems which must be considered in ray‐tracing studies are described next; and, finally, a few of the important areas for the application of ray tracing are noted.
Scattering of Electromagnetic Waves From a Tilted Slightly Rough Surface
Authors: Valenzuela G. R. 
Published: November 2015

The interaction of a plane wave and a slightly rough surface tilted away from a reference plane is investigated. Expressions for the scattered fields are obtained to second order for a perfectly conducting and a dielectric surface. In the limiting case of no tilt the fields agree with those of Rice. When the normal to the surface is rotated about the intersection between the incidence plane and the reference plane, the treatment yields important polarization effects and gives explicitly as a function of the tilt which irregularities on the surface contribute to the scattered power.Numerical results are obtained to investigate the relative magnitudes of the terms contributing to the cross sections.
Observation of Wind‐Produced Doppler Shifts in Tropospheric Scatter Propagation
Authors: Birkemeier W. P. , Merrill H. S. , Sargeant D. H. , Thomson D. W. , Beamer C. M. , Bergemann G. T. 
Published: November 2015

Persistent average frequency shifts obtained from phase data have been consistently observed on a 230‐km closed‐loop troposcatter circuit when the antennas were synchronously pointed off the great‐circle azimuth. The magnitude of the “Doppler shift” systematically increases with the antenna pointing angle from the great circle. The sign of the Doppler shift reverses across the great circle and depends upon the direction of the crosspath wind simultaneously observed in the lower common volume. Average Doppler shift data are presented for several fixed‐antenna‐offset and antenna‐beam‐swinging experiments conducted under varied meteorological conditions. Observations are interpreted in terms of atmospheric “scatterers” drifting across the path at the average crosspath wind speed. A model based on phase geometry is derived for the average Doppler shift and for Doppler spectra in terms of the crosspath wind velocity, antenna patterns and propagation mechanism.It is concluded that Doppler frequencies observed with a bistatic transhorizon microwave system depend primarily upon crosspath wind speed and the prevailing atmospheric structure. Crosspath motions thus appear to be an effective source of interference fading in tropospheric transhorizon propagation.
General Solution to the Problem of Reflection and Transmission by a Moving Dielectric Medium
Authors: Shiozawa T. , Hazama K. 
Published: November 2015

The present paper describes a general problem of reflection and transmission of a plane electromagnetic wave at the interface between a stationary dielectric medium and a dielectric medium moving in an arbitrary direction parallel to the interface. Either case of an incident E or H plane wave is treated.For the incident E plane wave the reflected wave is generally no longer an E plane wave but a linear combination of E and H plane waves, and similarly the transmitted wave has not only an E‐wave component but also an H‐wave component. For the incident E plane wave, in addition, the E‐wave components of the reflected and transmitted waves carry a positive power, but the H‐wave component of the transmitted wave always carries a negative power while the power carried by the H‐wave component of the reflected wave is always positive. Although the power flow with regard to the H‐wave component of the transmitted wave is negative, the total power transmitted is always positive. A similar argument applies also to the case of an incident H plane wave. The phenomenon of total reflection is shown as modified in ait interesting manner by the motion of a medium.
Coniugate Effects of Atmospherically Scattered Auroral Electrons
Authors: Rees M. H. 
Published: November 2015

Calculations and experiments have shown that some fraction of an electron stream incident on a gas is scattered in the backward direction. Applied to the aurora we find that about 15 to 20 percent of the electron flux returns up the field lines. These electrons are transferred to the conjugate region via the lines of force, if these are continuous between hemispheres. Losses are negligible, but a small drift in longitude may be expected. The energy spectrum of the electrons becomes softer; however, a close correspondence in occurrence of aurora must prevail. Absence of aurora would be a clear indication that the phenomenon is not associated with closed magnetic shells.A minor effect on the spectral character of the electrons scattered into the conjugate area is found, which could be associated with a difference in the model atmosphere and ionosphere.
Easing the Burden: Describing the Role of Social, Emotional and Spiritual Support in Research Families with Li‐Fraumeni Syndrome
Authors: Peters June A. , Kenen Regina , Bremer Renee , Givens Shannon , Savage Sharon A. , Mai Phuong L. 
Published: November 2015

AbstractThis study presents findings of a mixed‐method descriptive exploration of the role of friends and spirituality/religiosity in easing the burden of families with the rare inherited disorder, Li‐Fraumeni Syndrome (LFS). LFS is caused by germline mutations in the TP53 gene and is associated with very high lifetime risk of developing one or more malignancies. During the first clinical visit we assessed several types of social support among a subset of study participants (N = 66) using an established interactive research tool called the Colored Eco‐Genetic Relationship Map (CEGRM). We performed both quantitative and qualitative analyses of social relationships with LFS family members and close non‐kin. Distress scores (N = 59) were mostly low normal, with some outliers. We found that reported friendships varied widely, that the friendships were often deep and enduring, and were important sources of informational, tangible, emotional and spiritual support. Confidantes tended to be best friends and/or spouses. Organized religion was important in selected families, typically from mainstream traditions. However, a number of people identified themselves as “spiritual” and reported spiritual and humanist explorations. Our results shed preliminary light on how some people in families with LFS cope in the face of tremendous medical, social and emotional challenges.
Synthesis and Characteristics of Dodecyl Isopropylolamine and Derived Surfactants
Authors: Asadov Ziyafaddin H. , Rahimov Ravan A. , Mammadova Khuraman A. , Gurbanov Atash V. , Ahmadova Gulnara A. 
Published: November 2015

AbstractDodecyl isopropylolamine has been synthesized on the basis of dodecylamine and propylene oxide. The structure of dodecyl isopropanolamine has been determined by X‐ray diffraction, elemental analysis, IR‐ and NMR‐spectroscopic methods. Ionic surfactants have been synthesized by interaction of dodecyl isopropylolamine with various acids (HCl, HBr, acetic and propionic) and alkyl halides (methyl iodide, ethyl bromide and n‐propyl bromide). Colloidal‐chemical parameters, petroleum‐collecting and petroleum dispersing capacities of the synthesized cationic surfactants have been studied.
Rapid Quantitative Determination of Squalene in Shark Liver Oils by Raman and IR Spectroscopy
Authors: Hall David W. , Marshall Susan N. , Gordon Keith C. , Killeen Daniel P. 
Published: November 2015

AbstractSqualene is sourced predominantly from shark liver oils and to a lesser extent from plants such as olives. It is used for the production of surfactants, dyes, sunscreen, and cosmetics. The economic value of shark liver oil is directly related to the squalene content, which in turn is highly variable and species‐dependent. Presented here is a validated gas chromatography‐mass spectrometry analysis method for the quantitation of squalene in shark liver oils, with an accuracy of 99.0 %, precision of 0.23 % (standard deviation), and linearity of >0.999. The method has been used to measure the squalene concentration of 16 commercial shark liver oils. These reference squalene concentrations were related to infrared (IR) and Raman spectra of the same oils using partial least squares regression. The resultant models were suitable for the rapid quantitation of squalene in shark liver oils, with cross‐validation r2 values of >0.98 and root mean square errors of validation of ≤4.3 % w/w. Independent test set validation of these models found mean absolute deviations of the 4.9 and 1.0 % w/w for the IR and Raman models, respectively. Both techniques were more accurate than results obtained by an industrial refractive index analysis method, which is used for rapid, cheap quantitation of squalene in shark liver oils. In particular, the Raman partial least squares regression was suited to quantitative squalene analysis. The intense and highly characteristic Raman bands of squalene made quantitative analysis possible irrespective of the lipid matrix.
First Trimester Diagnosis of Sirenomelia
Authors: Kazi Amir Irfan , Iqbal Yasmin , Kazi Sana Elham 
Published: November 2015

AbstractSirenomelia is a rare congenital anomaly characterized by a single lower extremity which is associated with abnormalities in other organ systems, commonly affecting the gastrointestinal and the urogenital systems. It is sporadic with no increased risk in subsequent pregnancies. In almost all the cases of sirenomelia, a single umbilical artery (SUA) is present which arises from the abdominal aorta. Sirenomelia can be confidently diagnosed in the first trimester while the diagnosis in the second and third trimesters is rendered difficult due to the lack of amniotic fluid in the later gestation. Transvaginal ultrasound and color Doppler have a key role in making the diagnosis and 3D ultrasound helps in better demonstrating the abnormality.
The veil of experimental currency units in second price auctions
Authors: Drichoutis Andreas C. , Lusk Jayson L. , Nayga Rodolfo M. 
Published: November 2015

AbstractEconomic experiments often entail subjects making decisions with payoffs in experimental currency units (ECUs). Earnings in ECUs are converted to cash at the end of the experiment. Such a procedural choice seems to be driven more by habit or tradition than by empirical evidence that this is more appropriate to use.
We report results of a private, induced value second price auction (SPA) experiment in which we manipulate the exchange rate between ECUs and cash. We find virtually no relationship between a stronger/weaker experimental currency and the ability of theory to predict observed outcomes. The only significant effect relates to the comparison of the cash-only condition to the one-to-one exchange condition. The latter produced greater behavioral deviations from theoretical predictions. However, we find that this effect is largely driven by a handful of subjects. The results suggest that the use of ECUs is not a hindrance for experimental practice, at least not in the context of an induced value SPA.