bluuebunny/crossref_metadata_2025 huggingface dataset:
CCR9 AND CCR7 are overexpressed in CD4–CD8– thymocytes of myasthenia gravis patients
Authors: Li Qianru , Liu Pingping , Xuan Xiaoyan , Zhang Junfeng , Zhang Yun , Zhu Zhengkun , Gao Feng , Zhang Qingyong , Du Ying
Published: November 2015

Introduction: Chemokine CC motif receptors 9 and 7 (CCR9 and CCR7) play a major role in the migration of T‐cell precursors to the thymus to initiate T thymopoiesis. However, their role in development of T‐cells in myasthenia gravis (MG) patients has not been fully elucidated. Methods: Expression and distribution of CCR9+ and CCR7+ cells were detected by flow cytometry and immunofluorescence. Real‐time polymerase chain reaction was used to check the adhesion molecules on CD4–CD8– double‐negative (DN) thymocytes. Results: CCR9 and CCR7 expression by DN thymocytes increased in the MG thymus; the levels of CCR9, CCR7, interleukin‐7R mRNA increased, and CXCR4 levels decreased compared with levels in the non‐MG thymus. More CCR7 and CCR9 double‐positive (DP) thymocytes were gathered near the subcapsular region in MG thymus. Conclusions: Enhanced expression of CCR9 and CCR7 may complicate the differentiation of DP thymocytes from the DN stage in MG thymus. Muscle Nerve, 2016 Muscle Nerve 55: 84–90, 2017
Improved spectral resolution and high reliability of in vivo1H MRS at 7 T allow the characterization of the effect of acute exercise on carnosine in skeletal muscle
Authors: Just Kukurová Ivica , Valkovič Ladislav , Ukropec Jozef , de Courten Barbora , Chmelík Marek , Ukropcová Barbara , Trattnig Siegfried , Krššák Martin
Published: November 2015

The aims of this study were to observe the behavior of carnosine peaks in human soleus (SOL) and gastrocnemius (GM) muscles following acute exercise, to determine the relaxation times and to assess the repeatability of carnosine quantification by 1H MRS at 7 T. Relaxation constants in GM and SOL were measured by a stimulated echo acquisition mode (STEAM) localization sequence. For T1 measurement, an inversion recovery sequence was used. The repeatability of the measurement and the absolute quantification of carnosine were determined in both muscles in five healthy volunteers. For absolute quantification, an internal water reference signal was used. The effect of acute exercise on carnosine levels and resonance lines was tested in eight recreational runners/cyclists. The defined carnosine measurement protocol was applied three times – before and twice after (approximately 20 and 40 min) a 1‐h submaximal street run and additional toe‐hopping. The measured T1 relaxation times for the C2‐H carnosine peak at 7 T were 2002 ± 94 and 1997 ± 259 ms for GM and SOL, respectively, and the T2 times were 95.8 ± 9.4 and 81.0 ± 21.8 ms for GM and SOL, respectively. The coefficient of variation of the carnosine quantification measurement was 9.1% for GM and 6.3% for SOL, showing high repeatability, and the intraclass correlation coefficients (ICCs) of 0.93 for GM and 0.98 for SOL indicate the high reliability of the measurement. Acute exercise did not change the concentration of carnosine in the muscle, but affected the shape of the resonance lines, in terms of the shifting and splitting into doublets. Carnosine measurement by 1H MRS at 7 T in skeletal muscle exhibits high repeatability and reliability. The observed effects of acute exercise were more prominent in GM, probably as a result of the larger portion of glycolytic fibers in this muscle and the more pronounced exercise‐induced change in pH. Our results support the application of the MRS‐based assessment of carnosine for pH measurement in muscle compartments. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.
Expanding Thermal Plasma Deposition of Al‐Doped ZnO: On the Effect of the Plasma Chemistry on Film Growth Mechanisms
Authors: Williams Benjamin L. , Ponomarev Mikhail V. , Verheijen Marcel A. , Knoops Harm C. M. , Chandramohan Abhinaya , Duval Leo , van de Sanden Mauritius C. M. , Creatore Mariadriana
Published: November 2015

This work presents a review of expanding thermal plasma – chemical vapour deposition (ETP‐CVD) of Al‐doped ZnOtransparent conducting oxides (TCOs), alongside new results providing insights into the role of the plasma chemistry on film microstructure. Standard growth conditions generate high resistivities (>10−3Ω · cm) at low film thicknesses (<300 nm) as a result of a high grain boundary and void density. Microscopy studies of the early growth stage reveal that a high nucleation probability and strong <0002>‐texture are the causes of this microstructure. We investigate how the precursor feed composition (diethylzinc‐to‐O2 flow rate ratio) can be utilised to modify the growth mechanism and consequently reduce film resistivity (∼10−4Ω · cm), focussing on the role that this flow rate ratio has on the plasma chemistry developing in the downstream region of the expanding plasma (as supported by Langmuir probe and mass spectrometry measurements).
Efficacy of a Juncus effusus extract on grapevine and apple plants against Plasmopara viticola and Venturia inaequalis, and identification of the major active constituent
Authors: Thuerig Barbara , Ramseyer Justine , Hamburger Matthias , Oberhänsli Thomas , Potterat Olivier , Schärer Hans‐Jakob , Tamm Lucius
Published: November 2015

BACKGROUND

There is growing demand to replace chemical pesticides with alternatives owing to concerns related to impacts on human health and the environment. Plant‐derived plant protection products could provide sustainable and environmentally friendly alternatives to chemical products. The aim of this study was to identify plant and fungal extracts with so far unknown activity against important plant pathogens by in vitro screening of a library of more than 3000 extracts.

RESULTS

Several plant extracts with promising in vitro fungicidal activity (MIC100 ≤ 50 µg mL−1) towards one or several of the investigated pathogens (Venturia ineaqualis, Phytophthora infestans, Plasmopara viticola) were identified by the screening. One of the hits, an ethyl acetate extract of Juncus effusus L. medulla, was further investigated, and dehydroeffusol (DHEF) was identified as its main active constituent. On susceptible grapevine and apple seedlings, efficacies of up to 100% were reached with the extract (EC50 123 or 156 µg mL−1) and with DHEF (EC50 18 or 21 µg mL−1) against P. viticola and V. inaequalis respectively.

CONCLUSIONS

Our results demonstrate that plants can provide promising alternatives for integrated and organic farming. J. effusus shows high efficacy at low concentrations and, as an abundant perennial species, is an interesting candidate for the development of a novel plant protection product. © 2015 Society of Chemical Industry
Polarization engineering of c‐plane InGaN quantum wells by pulsed‐flow growth of AlInGaN barriers
Authors: Neugebauer Silvio , Metzner Sebastian , Bläsing Jürgen , Bertram Frank , Dadgar Armin , Christen Jürgen , Strittmatter André
Published: November 2015

Polarization‐field reduction in c‐plane InGaN multi‐quantum well (MQW) structures is achieved by pulsed‐flow growth of quaternary AlInGaN barriers using metalorganic vapor phase epitaxy (MOVPE). The pulsed‐flow growth allows for precise control of the quaternary composition at very low growth rate. In photoluminescence (PL) experiments a blue‐shift of the MQW emission wavelength is observed by successive adjustment of the AlInGaN barriers toward reduced polarization mismatch to the InGaN quantum wells. Accordingly, we find a decreasing radiative lifetime by time resolved cathodoluminescence (TRCL). The application of AlInGaN as barrier material instead of conventional GaN is limited by plastic relaxation. While for InGaN‐QWs emitting in the violet‐blue spectral region, fully polarization‐matched AlInGaN barriers can be realized, for long‐wavelength (green spectral region) severe lattice relaxation is observed leading to inferior optical properties as compared to binary GaN barriers.
Piezoelectric effect in GaAs nanowires: experiment and theory
Authors: Lysak Volodymyr , Soshnikov Ilya P. , Lahderanta Erkki , Cirlin George E.
Published: November 2015

The anomalous piezoelectric effect in GaAs nanowires was detected (the piezoelectric strain coefficient up to d33 ≈ 26 pC/N) that is 12 times larger than the theoretically estimated value. This result is explained by the dominant content of the phase with the wurtzite‐type crystal structure in GaAs nanowires and an increased pressing force by the contact layer on the nanowire. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)
Successful treatment of cytomegalovirus associated hemophagocytic lymphohistiocytosis with the interleukin 1 inhibitor – anakinra
Authors: Divithotawela Chandima , Garrett Peter , Westall Glen , Bhaskar Balu , Tol Maneesha , Chambers Daniel C.
Published: November 2015

Hemophagocytic lymphohistiocytosis (HLH) is a rare, frequently under‐recognized condition associated with multi‐organ failure and very high mortality. A 44‐year‐old woman was admitted with a 4‐day history of fever, headache, delirium, and dyspnea. She progressed rapidly to type 1 respiratory failure and required intubation and mechanical ventilation. Laboratory tests showed pancytopenia, abnormal liver enzyme levels, elevated triglyceride level, and elevated ferritin level. Bone marrow biopsy showed features of HLH. Computed tomography scan showed bilateral consolidation. Bronchoalveolar lavage was positive for cytomegalovirus. She was treated with ganciclovir, methylprednisolone, broad spectrum antibiotics, and cytomegalovirus hyperimmunoglobulin without clinical response. Given the poor prognosis and reports of success in pediatric HLH, anakinra 100 µg subcutaneously daily was commenced. There was rapid defervescence, resolution of delirium, and improvement in gas exchange, leading to complete recovery. This case illustrates successful treatment of HLH associated with cytomegalovirus pneumonitis with the interleukin 1 inhibitor anakinra.
Variation in Ionospheric Electron Content Measured by Radio Waves From Syncom 3
Authors: Nakata Yoshiaki
Published: November 2015

M.easurements of the Faraday rotation of a 136.98 Mc/s signal radiated from the geostationary satellite Syncom 3 is used to determine the time variation in the total electron content in the ionosphere. Gqod agreement of the time variation between the Faraday rotation and the square of J0F2is found, and the slope of the line of this relationship is determined by the distribution of electron density at a particular height. Absolute values of total electron content are determined from the intercept on the ordinate intersected by this line. Good agreement is maintained not only on the quiet day, but also on the disturbed day.
Ionospheric Measurements by Means of the Early Bird Geostationary Satellite
Authors: Checcacci P. F.
Published: November 2015

The VHF emission of the Early Bird geostationary satellite during the period June 23 to July 9, 1965, has been used for ionospheric measurements at Florence, Italy (43°48' N, 11°13' E). Electron content daily variation curves obtained from Faraday rotation measurements show a maximum‐to‐ minimum ratio of about 5. The equivalent slab thickness ranges from 140 to 310 km. The scintillation occurrence shows maxima at night and at noon.
Ray‐Tracing Study of HF Ducting Propagation With Satellites
Authors: Wong Ming S.
Published: November 2015

Ray patterns‐showing the spatial distribution of rays emitted from a transmitter and then progressively refracted in the medium‐ are presented for frequencies from 13.6 to 40 Mc/s, and for variations of the ionosphere in one to three dimensions. The patterns portray the elevated radio ducts, with down‐to‐earth contacts, responsible for long‐distance and round‐the‐world propagation. It is shown that constancy of Doppler frequency shift, in signal reception from an antipodal satellite pass, is a condition enabling the signal to persist some minutes, and that this constancy implies propagation off the great‐circle path .
Satellite ORBIS Experiment
Authors: Basu S. , Sarkar S.
Published: November 2015

Signals transmitted by satellite ORBIS at 10.004 Mc/s were received at Haringhata Field Station (geomagnetic lat. 12°15’ N, geomagnetic long. 32° W). Long‐distance propagation paths could be established between the station and the satellite in some passes, while a few overhead passes could not be received. Absence of signals from a few overhead passes is explained in terms of blanketing‐type sporadic E. It is concluded that long‐distance propagation paths may be sustained either by hop modes in the presence of irregularities in the ionosphere or by ionospheric dueling.
Gradient Instabilities as Possible Causes of Irregularities in the Ionosphere
Authors: Liu C. H. , Yeh K. C.
Published: November 2015

In this investigation a theory is proposed to explain the production of certain irregularities in the ionosphere. It is found that the region of the ionosphere below the peak of the electron distribution may become unstable because of the joint effect of the gravitational field and the positive electron density gradient there. The unstable modes are found to correspond to quasi‐transverse modes. For the case when only plasma is considered, the condition for instability to occur is gρ′p/v‐P > ξ, where g is the gravitational acceleration, ρp the plasma density, ρ′p its height gradient, v the ion‐neutral collisional frequency, and ξ the effective attachment coefficient. When the coupling between plasma and neutral particles is taken into account, an additional instability condition may occur when the neutral particle distribution has a positive density gradient.

This quasi‐transverse unstable mode is proposed as a possible causative mechanism for the formation of irregularities in the ionosphere. When either one of the instability criteria is satisfied, spontaneous generation of irregularities is possible. Some experimental evidence is presented and discussed.
Transmission Loss for Ionospheric Propagation Above the Standard MUF
Authors: Wheeler J. L.
Published: November 2015

Transmission loss for ionospheric propagation over a 4000‐km path from Maryland to Southern California has been measured experimentally at several frequencies in the HF band. The observed losses were in close agreement with those predicted at all frequencies near and below the st~dard maximum usable frequency (MUF). The observed losses exceeded those predicted whenever the frequency of the obliquely incident radiation exceeded the standard MUF. This excess loss was found to be that predicted by the Phillips‐Abel theory for evaluation of F, or F 2‐region reflected power on frequencies above the standard MUF. Loss predictions were made, taking into account geometric spreading of the radiation, ground reflection loss, E3‐region obscuration, and D‐region absorption for those frequencies when the entire path was not in darkness. Standard MUF values were calculated with the aid of ionosonde data from along the path, assuming transmission via two F‐layer reflections.
U.S.A. National Committee Report, Fifteenth URSI General Assembly, Munich, September 1966: Commission 1, Radio Measurement Methods and Standards: Progress in Radio Measurement Methods and Standards
Authors: Richardson John M. , Beatty R. W. , Birnbaum George , Bussey H. E. , Cohn Seymour B. , Gerber E. A. , Hudson George E. , Mockler R. C. , Selby M. C. , Sykes R. A. , Weinschel Bruno O.
Published: November 2015

Atomic frequency and time interval standards had advanced to such a high level of performance that in October 1964, the International Committee of Weights and Measures designated the (F = 4, mF = 0) ⇄ (F = 3, mF = 0) transition in the ground state of Cs133 temporarily for the physical measurement of time.
Effective Recombination Coefficient in the D Region
Authors: Parthasarathy R. , Rai D. B.
Published: November 2015

Multiple‐frequency (5‐50 Mc/S) radio wave absorption data taken during a polar‐cap event is used to derive an electron density profile for the lower ionosphere. By comparing this profile with an ionization rate profile calculated using measured particle flux, the effective recombination coefficient is obtained for the 50‐90 km height region.
Application of Conformal Mapping to Earth‐Flattening Procedures in Radio Propagation Problems
Authors: Richter Juergen H.
Published: November 2015

The propagation of electromagnetic waves around a cylinder is rigorously treated by the application of conformal mapping. The cylinder is surrounded by a nonmagnetic isotropic medium whose dielectric constant is a function of the radius. It is transformed into a Cartesian system filled with a fictitious medium whose dielectric constant and magnetic permeability are functions of height. The wave equations for a TM and a TE wave are given.

Wave propagation around a cylinder represents an approximation to wave propagation around a sphere (e.g., the earth) when the influence of the curvature of the sphere perpendicular to the direction of propagation can be neglected. It is shown that the conformal mapping applied to the cylinder yields an earth‐flattening technique which agrees with first‐order approximations obtained in spherical coordinates.

Pryce treats wave propagation around the earth in spherical coordinates using a range transformation suggested by Pekeris and a height transformation suggested by Copson. It will be shown in this paper that both independently proposed transformations follow directly from the application of conformal mapping.
Further Observations of Sunrise and Sunset Fading of Very‐Low‐Frequency Signals
Authors: Crombie D. D.
Published: November 2015

An earlier explanation of sunrise and sunset fading on long VLF paths is confirmed by examining data taken over a wider range of frequency and directions of propagation. It is found, however, that there is an appreciable dependence of the fading period on the magnetic direction of propagation. It is shown that this dependence is qualitatively in agreement with what would be expected from a sharply bounded ionosphere and a transverse magnetic field.
Rocket Observations of Sporadic E and Related Features of the E Region
Authors: Smith L. G.
Published: November 2015

Observations of structural features of the electron density profile of the E region are presented. These were obtained using a rocket‐borne probe having a resolution of about 10 m in height and about 1 percent in electron density. Daytime profiles show thin‐layer Es having sharply defined upper and lower boundaries and a thickness of a few km. At night, the profiles at midlatitudes are characterized hy the generally irregular nature below 120 km. The marked tendency to horizontal stratification is noted.
Doppler Frequency Changes in Radio Waves Propagating Through a Moving Ionosphere
Authors: Jacobs J. A. , Watanabe T.
Published: November 2015

Doppler frequency changes for a vertically incident and reflected radio wave caused by a redistribution of electrons in the ionosphere due to drift motions set up by an electric field across the earth's main magnetic field are discussed. The Doppler frequency change is given as a linear function of the two horizontal components of the electric field with coefficients which are functions of the relevant ionospheric parameters and the frequency of the sounding radio wave. The Doppler frequency. change can also be given as a function of the intensity of the magnetic variation, provided that a suitable relation can be found between the intensity of the magnetic variation observed on the earth's surface and the intensity of the electric field in the ionosphere. The Doppler frequency change has been given in this way for two cases; one is for a uniform time‐changing magnetic field parallel to the geomagnetic axis which roughly represents the Chapman‐Ferraro field for sudden commencements of geomagnetic storms. The other is for the field due to alternating electric currents in the ionosphere. Several theoretical predictions have been made which can be compared with observations. The amount of the Doppler shift is about 1 c/s in middle latitudes for a 4‐Mc/s sounding wave for a sudden commencement with a time scale of 4 min, and magnitude several tens of gammas. The Doppler shift due to alternating currents in the ionosphere amounts to only 1 c/s for a 4‐Mc/s radio wave with a 50‐y amplitude of oscillation in the magnetic field intensity.
Justification of the Use of Multiple Isothermal Layers as an Approximation to the Real Atmosphere for Acoustic‐Gravity Wave Propagation
Authors: Pierce Allan D.
Published: November 2015

The validity of the multilayer approximation for the study of acoustic‐gravity wave propagation in the atmosphere is demonstrated in the limit of small layer thicknesses. The principal basis of the justification is the existence of two coupled first‐order differential equations with coefficients which do not depend explicitly on derivatives of the sound speed with respect to height.
Wave Propagation in Drifting Isotropic Warm Plasma
Authors: Unz H.
Published: November 2015

The electro‐magneto‐plasma‐gas‐dynamics (EMPGD) equations are given for the warm, compressible electron gas, with no magnetostatic field, drifting with a constant velocity, by taking into account the fluid dynamics variables of the electron gas and using small‐signal theory. Assuming harmonic time variation, an algebraic equation is found for the refractive index of the plasma characteristic waves. Particular cases are discussed and compared with previous results.
A Summary of Papers Presented at the Conference on Atmospheric Limitations to Optical Propagation
Authors: Meyer‐Arendt Jurgen R.
Published: November 2015

This is a brief summary of all papers presented at the 1965 Conference on Atmospheric Limitations to Optical Propagation, held at the Central Radio Propagation Laboratory, Boulder, Colo.
Contour Plots for the Diffraction of a Pulse By a Wedge
Authors: Makhoul John I.
Published: November 2015

Using Friedlander's solution for the diffraction of a pulse from a wedge, contours of constant electric and magnetic field are plotted for an electromagnetic plane wave pulse incident on a perfectly conducting wedge for different wedges and angles of incidence, and for TM and TE polarizations.
Alternative Representations of Source‐Excited Vector and Scalar Fields
Authors: Felsen Leopold B. , Marcuvitz N.
Published: November 2015

Radiation from electromagnetic sources in layered regions is reviewed and illustrated for the case of planar stratification. Mter a reduction of the vector field problem to equivalent scalar Green's function problems, the latter are expressed in alternative forms by the systematic application of one‐dimensional characteristic Green's function techniques. Solutions are derived in this manner without the intervention of the classical Watson procedure and are interpretable as guided‐wave representations along various coordinate directions. Considerations pertaining to scalar Green's functions apply directly, upon suitable reinterpretation of the electromagnetic parameters, to other fields such as the acoustic which are derivable from scalar potentials.
Transverse Propagation of Waveguide Modes Cylindrically Stratified Magnetoplasma
Authors: Wait James R.
Published: November 2015

An exact solution is given for the problem of a magnetic line source in the presence of an isotropic conducting cylinder which is surrounded by a concentric stratified plasma. The d‐c magnetic field is alined with the cylindrical axis. The harmonic series representation is transformed to a more highly convergent form which facilitates computation for large cylinder radii. In this case, the field is expressed as a sum of modes which propagate around the cylinder in opposing directions. The presence of the d‐c magnetic field destroys the usual azimuthal symmetry in problems of this type. It is indicated that the situation is somewhat analogous to the propagation of radio waves in a spherical earth‐ionosphere system.
Theory of Duct Propagation of Whistler Radio Waves
Authors: Adachi Saburo
Published: November 2015

The previous theoretical analysis by the present author on the propagation of whistler radio waves along an enhanced or depressed magnetoplasma slab imbedded in an infinite magnetoplasma is extended to include the general case of an arbitrary thickness of the slab. As a result, two different types of completely guided waves are found to exist in general. The one guided wave is essentially a surface wave trapped along an interface between two semi‐infinite plasmas of different plasma densities, while the other guided wave is a duct type of surface wave in which the whistler plane wave is predominantly propagated inside the slab by the successive total reflections at the walls of the slab and is propagated along the depressed plasma slab only. Dispersion properties of these completely guided waves are studied in detail.
Groundwave Propagation Across Semi‐Infinite Strips and Islands on a Flat Earth
Authors: King R. J. , Tsukamoto W. I.
Published: November 2015

An electromagnetic groundwave propagating along the surface of the earth will be partially transmitted and partially reflected at an abrupt electrical discontinuity such as a coastline, lake, island, peninsula, river, certain types of mineral deposits, etc. The theoretical work of Wait is extended to yield a solution which can be applied to semi‐infinite or finite ground plane inhomogeneities of arbitrary shape. Calculations were made for two special cases: perpendicular propagation near a semiinfinite strip (e.g., a peninsula), and near a small rectangular island.

The theoretical solution was experimentally verified to a good order of accuracy through the use of microwave‐frequency (4.3 Gc/s) laboratory models on which both amplitude and phase measurements were made. In these models, water was used to simulate imperfectly conducting media, while aluminum plates simulated perfectly conducting media. It is shown that the position of a semiinfinite strip or island transverse to the direction of propagation has considerable influence on the phase of the transmitted signal.
Potentials for Cylindrical Warm Plasmas
Authors: Maurice I. Sancer
Published: November 2015

The plasma which is analyzed is described by the linearized electron‐fluid equations, and source terms are included. Anisotropic effects which are caused by the presence of an externally applied constant axial magnetic field are included in this analysis. It is shown that a set of three potentials can be introduced, provided a three‐by‐three matrix can be diagonalized. For the model without the magnetic field this matrix is diagonalized. Two of the resulting potentials are then shown to be scalar multiples of the Hertzian potentials for the electromagnetic part of the equations and the remaining potential is a scalar multiple of the pressure. A brief outline is included to show how 2 + n potentials could be introduced for the anisotropic multiftuid model.
Precautionary Note on Stratification
Authors: Adams Roy N. , Denman Eugene D.
Published: November 2015

In this paper, a stratified model of a linear refractive index profile is shown to produce artificial interference phenomena if the stratum thickness is improperly chosen. An isotropic, time invariant medium has been selected for computational purposes. The exact method of invariant imbedding is used for the numerical analysis.
Electromagnetic Propagation in an Crust Waveguide
Authors: Wait James R.
Published: November 2015

An electromagnetic waveguide in the earth's crust is idealized as a homogeneous lossy dielectric slab which is bounded by two homogeneous semi‐infinite conducting media. The source is a vertical electric dipole which is either above or below the upper surface of the horizontal slab. The exact integral formula for the field is evaluated by function‐theoretic means. It is shown that the dominant contributions are the propagating waveguide modes in the slab, although the lateral waves should not be ignored. The excitation of the waveguide modes and the relevant height‐gain and depth‐gain functions are also discussed. The attenuation characteristics of the modes are considered in some detail. It is shown that the principal loss mechanisms are the ohmic dissipation within the waveguide and the energy transmitted through the upper and lower walls into the bounding media. A numerical example is chosen where all three loss mechanisms are of the same order of magnitude.
A Bistatic Radar Method for the Determination of ε and µ for a Smooth Spherical Target
Authors: Erteza A. , Doran J. A.
Published: November 2015

This paper presents an application of the concept of differential reftectivity relating to the determination of the permeability and permittivity of the material composing a smooth reftecting sphere. Expressions for these parameters are derived which depend on measurements of relative scattered power in a bistatic radar or optical experiment. Absolute power measurements are not necessary; only the ratio of the powers received by two quadratically opposed antennas is needed. This ratio must be determined for two different configurations of source, target, and observation point. The first‐order terms obtained by this method can be readily verified by geometrical optics.
The “Infinity Catastrophe” Associated With Radiation in Magnetoionic Media
Authors: Staras Harold
Published: November 2015

In recent years many papers have appeared in the technical literature dealing with the question of radiation from sources imbedded in magnetoionic media. Most of these papers, which have restricted their consideration to media described by the Appleton‐Hartree dielectric tensor, have come to the conclusion that the radiation resistance of a point dipole may be infinite in some regime of magnetoionic parameters even if the medium itself is lossless. Recently, two authors have purported to show, by introducing arguments of time reversibility, that the “infinity catastrophe” that appeared in the earlier papers is due to an incorrect formulation of the problem and that if the correct formulation were used the infinity would disappear. This paper reexamines the fundamenJal formulas for radiation in magnetoplasmas and concludes that the formulas used by earlier authors are valid and that the “infinity catastrophe” arises not from the method of calculation but rather from a physical inconsistency in the Appleton‐Hartree dielectric tensor.
Radiation and Propagation of Electromagnetic Waves from Moving Sources
Authors: Lewis Robert M. , Pressman Walter
Published: November 2015

The electromagnetic field produced by a general point source moving on an arbitrary trajectory an infinite homogeneous medium is obtained by solving an initial value problem for Maxwell's equations. The solution is expressed parametrically with the aid of bicharacteristics or space‐time rays. This representation, which is equivalent to the more common “retarded time” representation is used because it clarifies the space‐time geometry of the solution. For the case of a moving charge, the solution reduces to a standard result.

In a sequel, the results obtained will be applied to the problem of radiation and propagation of electromagnetic waves produced by point sources moving in an inhomogeneous medium.
A Modifiec;l Fock Function for the Distribution of Currents in the Penumbra Region With Discontinuity in Curvature
Authors: Hong S. , Weston V. H.
Published: November 2015

A modified Fock function is obtained to describe the current distribution on a smooth convex boundary, composed of a flat plane smoothly joined to a parabolic cylinder with the join in the penumbra region. Both analytical and numerical methods are used to obtain the modified Fock function which now depends on the distance between the shadow boundary and the flat plane‐parabolic cylinder join. The modified Fock function is applied to estimate the backscattering cross section of a cone‐sphere.
Some Highlights of a Symposium on Subsurface Propagation of Electromagnetic Waves, Paris, April 25–28, 1966
Authors: Wait James R.
Published: November 2015

On the dates indicated, a symposium was held at the Ministry of Posts and Telecommunications in Paris on the subject of “subsurface communications.” This was held under the auspices of the Advisory Group for Aerospace Research and Development of NATO. The program chairman was Dr. Philip Newman of the U.S. Air Force Cambridge Research Laboratories, while the French committee members were Professor M. Bouix and Capt. P. Halley.
Introductory Paper Review of Current Methods for Obtaining Electron‐Density Profiles From lonograms
Authors: Wright J. W. , Smith G. H.
Published: November 2015

Certain aspects of the general ionogram analysis problem, common to most methods of attack, are discussed as an introduction to the papers of this series. Present attainable accuracies and criteria affecting the choice of method for typical problems are discussed. This paper contains, in part, results of discussions of the URSI‐CIG Subcommittee on N(h) profiles held at its meeting in London, May 1964.
Ionospheric Electron‐Density Profiles With Continuous Gradients and Underlying Ionization Corrections. III. Practical Procedures and Some Instructive Examples
Authors: Wright J. W.
Published: November 2015

A description is given of procedures developed at the Institute for Telecommunication Sciences and Aeronomy (ITSA) to permit accurate extraction of virtual‐height data from ionograms in a form easily usable by digital computers. Criteria are described for identification of the significant interval limits along ionogram echo traces.
Computation and Application of Synoptic Ionospheric Profiles
Authors: Laird A. R. , Wright J. W.
Published: November 2015

Results from the Institute for Telecommunication Sciences and Aeronomy (ITSA) synoptic surveys of ionospheric morphology by systematic calculation of large numbers of electron‐density profiles are described. Averages of individual hourly profiles provide a quantitative measure of the day‐to‐day variability of the ionosphere in addition to much information concerning average ionospheric structure. The average profiles can also be obtained from a ‐composite virtual“height curve” representing all of the observations at a given hour in a month. It is shown that these two ways of obtaining averages are equivalently useful for survey purposes. Observations from five years of profile calculations using both systems illustrate the decrease of F‐region electron content, height of peak density, and characteristic thickness with decreasing solar flux in a 12‐month running average.
Long‐Periodic Dipole Antenna
Authors: Cheong Weng‐Meng , King Ronold W. P.
Published: November 2015

A 12‐element log‐periodic dipole antenna is investigated with the three‐term theory described and verified experimentally in a companion paper (Cheong and King, 1967). The general frequency‐independent behaviour for the distributions of current, the driving‐point admittances, and the power for all elements over a wide range of frequencies. The driving‐point admittance, field pattern, beam width, and minor‐lobe level are determined for the antenna over the same frequency range. The director and reflector action of the elements is pointed out. It is concluded that a new and powerful tool is available for the complete and accurate analysis of log‐periodic dipole antennas.
A Nomenclature for Oblique Ionospheric Soundings and Ray Tracing
Authors: Davies Kenneth
Published: November 2015

This is a short note drawing attention to the recommendations of international working parties (at Lindau, Germany and Leicester, England) concerning descriptive nomenclature and standard parameters for use in oblique ionospheric radio propagation. The description of oblique ionograms involves the use of terms such as lowest observed frequency, maximum observed frequency, and junction frequency. Path structure is defined by reflections from ionosphere and ground starting at the transmitter. This method is extended to the case of backscatter. Finally, for intercomparison of magnetoionic ray‐tracing programs, standard numbers are suggested for the earth's radius, the free‐space velocity, and the geomagnetic field.
Electromagnetic Radiation in a Moving Lossy Medium
Authors: Fujioka H. , Kumagai N.
Published: November 2015

This paper treats electromagnetic radiation from sources immersed in an isotropic lossy nondispersive medium moving at nonrelativistic uniform velocity. The inhomogeneous wave equations for the radiated fields are derived and are solved by means of a suitable transformation of the dependent variables. The well‐known radiation phenomena are found to be modified when the moving medium is lossy. The results show that, in general,

(1) the far‐zone field is elliptically polarized,

(2) the far‐zone electric and magnetic fields are not mutually perpendicular,

(3) the far‐zone Poyntinjl: vector is not purely radial.

As an illustrative example, the case in which the source is an oscillating dipole is worked out in detail.
Spherical Wave Propagation Through a Random Continuum
Authors: deWolf D. A.
Published: November 2015

An earlier computation of the correlation functions of the components of the electric field resulting from the propagation of high‐frequency spherical waves through an intermediate layer containing a weak dielectric random continuum is generalized so that the results hold for a Wide class of dielectric two‐point correlation functions.
Radiation and Scattering Problems in Compressible Plasmas. Part I. Solutions by Ray Optics
Authors: Felsen Leopold B. , Labianca F. M.
Published: November 2015

Ray‐optical concepts are introduced for propagation of electromagnetic and electroacoustic waves in an unbounded compressible plasma, and are then applied to the analysis of radiation in the presence of plane or curved interfaces and obstacles. The method involves tracing of the electromagnetic and acoustic rays through the medium, due account being taken of coupling in source regions, at boundaries, and at scattering centers. The formulas for reflected, refracted, and diffracted fields derived in this manner are verified for special cases by the rigorous treatment in part II, thereby providing confidence in the validity of the procedure.
Computations of the Resistance of a Short Antenna in a Warm Plasma
Authors: Kuehl H. H.
Published: November 2015

The input resistance of a shon filamental antenna in a warm isotropic plasma is computed for several antenna lengths and for a wide range of frequencies. These computations, which are based on kinetic theory, are compared with the result of the hydrodynamic equations. The comparison shows that the hydrodynamic result is incorrect below the plasma frequency, but is a good approximation above the plasma frequency if the antenna is long compared to a Debye length. For antenna lengths comparable to a Debye length, however, the hydrodynamic result is valid only at frequencies far above the plasma frequency.
Theory of the Balanced Helical Wire Antenna
Authors: Chen Chin-Lin
Published: November 2015

A finite, balanced helical wire antenna excited by a delta‐function generator is investigated. The geometry of a helical wire is examined and an exact integral equation for the current distribution along the antenna is formulated. For a thin helical wire, the exact integral equation can be approximated by a one‐dimensional approximation, which can be solved by a Fourier‐series method. In the solution, the logarithmic singularity at the driving point is taken into account and is subsequently subtracted out. Thus, the input admittance is obtained. The theoretical results are compared with the experimental result. It is found that the current amplitude decays exponentially. This is contradictory to the usual assumption that the current along a helical antenna is a traveling wave with a constant amplitude.
Admittance of a Plasma‐Covered Cylindrical Antenna
Authors: Meltz G. , Freyheit P. J. , Lustig C. D.
Published: November 2015

Based on a variational formulation, an expression is derived for the admittance of a circumferential gap in an infinite cylinder covered by a set of coaxial dielectric or plasma layers. The gap is fed by the dominant TEM mode in a narrowly spaced, parallel‐plate, radial waveguide. Numerical computations are presented for a multiple‐layer model of a lossy plasma and for a dielectric layer which supports surface waves. These computations are compared with admittance measurements of a similarly excited metal cylinder surrounded by an annular plasma. The plasma is produced in a long double‐ wall cylindrical vessel by a pulsed d‐c discharge in argon at 0.4 Torr. In the experimef.lt, the radial guide is excited by a small axial probe fed by a conventional coaxial air line. The admittance viewed in the coaxial line is related to the gap admittance by an experimentally determined two‐port network representing the junction region. The measurements are in fair agreement with calculated values based on a three‐layer model of the inhomogeneous plasma and the discharge tube.
Waves in a Partially Ionized Paramagnetic Gas
Authors: Hodges R. R.
Published: November 2015

The nature of electromagnetic wave propagation in a partially ionized paramagnetic gas in a static magnetic field is explored. It is necessary to characterize such a medium by second‐order tensor expressions for both the permittivity and permeability, the former being that characteristic of an ordinary magnetoplasma, and the latter that for a magnetized paramagnetic medium. Employing linearized forms of these and Maxwell's equations leads to a general dispersion relation. For lossless conditions it is shown that the resonances and cutoffs associated with the free electrons and those due to the paramagnetic constituents are independent. This leads to some interesting, hypothetical propagation conditions that may exist in planetary or stellar atmospheres.

Application of this theory is made to the ionosphere, in which atomic oxygen is the major para‐magnetic constituent. Accounting for collisional losses, it is shown that the upper limit of the absorption at the peak of the atomic oxygen electron spin resonance line in the ionosphere is only 5 × 10ߚ4 times the background absorption due to the free electrons; the effect of Doppler broadening would be to decrease this number. The minute nature of this absorption line is supported by the apparently complete lack of experimental evidence of electron spin resonance effects on radio wave propagation in the terrestrial ionosphere. It is also shown that the internal radiation (noise) in the ionosphere must exhibit a similarly weak absorption line at the electron spin resonance, due to the nonequilibrium nature of the energy distribution of the free electrons.
Infinite Cylindrical Dielectric‐Coated Antenna
Authors: Ting Chung-Yu
Published: November 2015

A cylindrical antenna of infinite length imbedded in a concentric dielectric rod has been studied in detail by using a Fourier transform technique. The antenna radius is held constant while the thickness of the dielectric rod is varied over a wide range. The results have been compared against the corresponding properties of an infinite antenna in free space. It is found that the presence of the dielectric gives rise to a transmission current in addition to the radiation current. Increasing the thickness of the dielectric layer tends to increase the transmission current, decrease the radiation current and made the radiation pattern more broadside.
Phase Measurements of VLF Transmissions Over an 11,000‐km Transequatorial Path
Authors: Scarabucci R. R. , de Mendonça F.
Published: November 2015

Phase measurements of the 18.6‐kHz transmissions from Jim Creek were recorded during 1964 and 1965 at São Jose dos Campos (SP). Brazil. The diurnal signal phase variation presents an average time shift delay of 80 µs, which is rather regular throughout the year. The behavior of the phase rate of change during sunrise and sunset is discussed in terms of the interference pattern of propagation modes and in terms of the angle between the sunrise (and sunset) line and the transmitter‐receiver great circle path. Experimental evidence permits one to conclude that the phase‐path reflection height is a strong controlling factor of the second‐order mode propagation. Observations also show that the angle mentioned above is an important parameter in VLF phase studies.
A Numerical Investigation of Classical Approximations Used in VLF Propagation
Authors: Pappert Richard A. , Gossard Earl E. , Rothmuller Ilan J.
Published: November 2015

A computer program based on formalism developed by Budden will be used to evaluate the adequacy of some approximations that have been used in VLF waveguide propagation studies. The program makes allowance for the inhomogeneity and anisotropy of the lowest part of the ionosphere, allows for earth curvature, and may be used for arbitrary direction of propagation at any latitude.

The results of this program will be compared with calculations of Wait and Spies who used a model ionosphere consisting of an exponential variation for both electron density and collision frequency. This comparison will allow us to demonstrate a close numerical equivalence between the modified refractive index formulation and the spherical coordinate formulation as implemented by Wait and Spies. Also, it will be shown that an approximation introduced by Wait and Spies during the course of applying the effective surface impedance concept, though quite valid for first‐order mode calculations, is inadequate for daytime second‐order mode calculations.
On Rytov's Method
Authors: Taylor Leonard S.
Published: November 2015

Rytov's method (method of smooth perturbations) has been used extensively to solve problems involving wave propagation in turbulent media. The closure procedure employed in the Rytov theory is, however, questionable. In this paper the Rytov result is compared with the results of the perturbation theory of linear stochastic operators. It is shown that the Rytov method does not yield the field correct to first order in the pertur‐bation parameter, and it is concluded that the method is not generally valid beyond the limits of the Born (single‐scatter) approximation.
Some Spectral Characteristics of the Radio Refractivity in the Surface Layer of the Atmosphere
Authors: Bean B. R. , Emmanuel C. B. , Krinks R. W.
Published: November 2015

Experimental data suggest that the spectral density of the radio refractivity, N, exhibits a strong dependence on stability (Richardson's number, Ri) at the low frequency range and a weak dependence on stability at the high frequency range. Furthermore, the average spectral decay of N was found to be in reasonably good agreement with the “−5/3” law; however, significant departures from this law were observed depending upon the frequency range considered. In fact, systematically smaller spectral decays were observed at low frequencies and larger decays at high frequencies.
Zenneck Memorial Lecture
Authors: Goubau Georg
Published: November 2015

We are assembled here this evening to commemorate one of the pioneers in radio science, Prof. Jonathan Adolf Wilhelm Zenneck. The occasion and the location of this meeting could not have been chosen more appropriately. This is the first General Assembly of URSI to be held in Zenneck's native country, Germany. Zenneck was a great advocate of URSI. Before World War II, he was chairman of the German National Committee and vice president of URSI, two posts which are now held by one of his former students, Professor Dieminger. After the War, Zenneck was elected honorary president of the German National Committee.
Anomalous Sunrise Effects Observed on a Long Transequatorial VLF Propagation Path
Authors: Lynn K. J. W.
Published: November 2015

One year's observations of VLF transmissions from NLK received over a long transequatorial path at Smithfield, South Australia, are described. Phase cycle slipping on this path is common and is shown to be an integral part of the direct path modal interference pattern during the sunrise transition. The seasonal variation of cycle slipping and the sunrise fading is shown to be a function of the angle made by the propagation path with the sunrise line. The occurrence of phase cycle slipping and the associated fade spacing anomalies are interpreted as arising from anomalously high mode conversion when the sunrise line is in the vicinity of the geomagnetic equator.