bluuebunny/crossref_metadata_2025 huggingface dataset:
The potential role of an active deep ocean for climatic change
Authors: Piehler Hans , Bach Wilfrid
Published: February 2008

Two versions of a one‐dimensional upwelling‐diffusion energy balance model coupled with a carbon cycle model are compared. One version has a constant upwelling velocity, whereas in the other model the upwelling velocity depends on the surface temperature change in a nonlinear way. It is assumed that the physical processes leading to diffusion and advection both of energy and carbon dioxide in the deep ocean are identical and can be described with identical parameter values. This reduces the number of degrees of freedom of the coupled models relative to the noncoupled models. The transport parameters of the two versions were fitted simultaneously to both the observed carbon dioxide concentrations in the atmosphere and the observed temperature anomalies from 1860 to 1988 by the least squares method. The sum of squares obtained from the fit of the nonlinear version is significantly smaller than that of the linear version for both the carbon dioxide concentration in the atmosphere and the temperature anomalies from 1860 to 1988, although there are two more parameters in the nonlinear version. Another feature of the nonlinear version is that the climate sensitivity parameter is fixed (in our case to 2.5 K) and cannot be changed over the wide range of 1.5 K to 4.5 K as used in the linear version. Even small changes in this parameter result in large changes of the calculated temperatures. Furthermore, the nonlinear version shows the remarkable feature of calculating nonincreasing temperatures for the period 1940 –1980. The nonlinear dependence of advection velocity on surface temperature change enables the upwelling‐diffusion energy balance model to oscillate.
Nonlinear transformation of directional wave spectra in shallow water
Authors: Abreu M. , Larraza A. , Thornton E.
Published: February 2008

A shallow water, nonlinear spectral wave transformation model is developed for conditions of a mild sloping bottom (μ = ∇h/kh ≪ 1) and small amplitude effects (ε = ζ/h ≪ 1). Nonlinearities and combined shoaling and refraction effects act on the same time and length scales. The evolution equation of the wave action is prescribed by the wave Boltzmann equation, whereby resonant collinear triad interactions transfer energy among Fourier components. Combined shoaling and refraction effects are taken into account through the geometrical optics approximation. A numerical solution of the three‐wave collision integral is presented, and the steady state wave Boltzmann equation is integrated using a piece wise ray method. The model is tested using the high‐resolution frequency‐directional wave spectra of Freilich, Guza, and Elgar (1990) that show nonlinear transfers of energy between both harmonic and nonharmonic frequencies. A digitized version of the measured frequency‐directional spectrum at 10‐m depth is evolved 246 m shoreward over a bathymetry of straight and parallel bottom contours to 4‐m depth. The model predicts the prominent spectral features in the measured wave field. The model results are in general superior to estimates using linear, finite depth wave theory, and they compare well with the observations in the region of the spectrum dominated by nonlinear effects.
N‐bursty emission from Uranus: A cyclotron maser source?
Authors: Curran D. B. , Menietti J. D.
Published: February 2008

Ray tracing studies of RX‐mode emission from the north polar regions of Uranus indicate that the n‐bursty radio emission may have a source along field lines with footprints near the northern magnetic pole (perhaps in the cusp), but not necessarily associated with regions of strong UV emission. This is in contrast with similar studies for the Uranus nightside smooth radio emission, which are believed to be due to the cyclotron maser instability. Source regions can be found for both hollow and filled emission cones and for frequencies well above the local gyrofrequency implying that mechanisms other than the cyclotron maser mechanism may be operating.
Measurements of stratospheric NO2 by the improved stratospheric and mesospheric sounder
Authors: Reburn W. J. , Remedios J. J. , Ballard J. , Lawrence B. N. , Taylor F. W.
Published: February 2008

Limb sounding measurements of infra‐red emission at 6.2 μm from the Earth's atmosphere have been made by the Improved Stratospheric and Mesospheric Sounder (ISAMS). This provides a pressure modulated gas‐correlation signal and a wideband signal from which NO2 and aerosol extinction at 6.2 μm are jointly retrieved between 100 mb and 0.3 mb. The retrieval scheme is discussed with reference to NO2 and a qualitative comparison made with LIMS data. The ISAMS Northern hemisphere NO2 data for January 9th 1992 are then examined and the importance of dynamical factors highlighted.
Ultralow‐frequency fluctuations at the magnetopause
Authors: Lakhina G. S. , Shukla P. K. , Stenflo L.
Published: February 2008

A high‐β model for the generation of ultralow‐frequency (ULF) fluctuations at the magnetopause is presented. The ULF waves are excited by the density gradients in the magnetopause boundary layer. For β varying between 0.1 and 1.0, and for realistic values of the density gradients, the frequency range of the excited modes, their transverse wavelengths and their phase velocities parallel and perpendicular to the geomagnetic field lines seem to be in agreement with recent observations of Alfvénic structures at the magnetopause.
On the auroral double‐layer criterion
Authors: Kan J.R. , Lee L.C.
Published: February 2008

It is shown that the minimum electron streaming speed required in the Bohm‐Block criterion for the existence of one‐dimensional double‐layer solutions can be relaxed by the presence of a sufficient population of trapped electrons with energies in the parallel motion ranging up to the double‐layer potential energy. The resulting auroral double‐layer criterion is found to be relatively independent of the forms of the particle distribution functions. The trapped electrons can be identified with the energy‐degraded primary electrons and the secondary electrons on auroral field lines. The magnetic mirror due to the converging geomagnetic field and the electron‐neutral collisions in the upper atmosphere are necessary elements in building up the trapped electron population.
Ion sputtering from satellite surfaces
Authors: Hanson W. B. , Sanatani S. , Hoffman J. H.
Published: February 2008

The interaction of neutral and charged atmospheric particles with the surfaces of spacecraft moving at orbital velocities releases positive ions that are detected by the ion mass spectrometer and retarding potential analyzer on the Atmosphere Explorer spacecraft. The emitted particles have a characteristic energy of approximately 1 ev in the spacecraft frame of reference and lack the normal ram energy possessed by the ambient ions. Alkali ions Na+ and K+, as well as nonionospheric NO+ and O2+, are observed at low altitudes. All these except NO+ appear to be released by impacts of neutral N2 or O2 with the surfaces. These ion currents decrease with a time constant of approximately 6 weeks for the alkali and 4 weeks for the O2 ions. The efficiency of the impact process is approximately one ion released for each 106 N2 or 105 O2 collisions. Alkali ions are also released by collisions of O+ ions with such surfaces, with the efficiency 3 × 10³ O+ impacts per ion released. The scale heights of the alkali ion currents follow that of N2 and O2 at low altitudes and that of O+ at altitudes above 300 km, where O+ becomes their dominant source. NO+ ions appear to be formed by O collisions with the surfaces. Their abundance is highly variable, indicating that the supply of surface nitrogen atoms is greatly variable.
HF radar observations of pulsations near the magnetospheric cusp
Authors: Walker A. D. M. , Greenwald R. A. , Baker K. B.
Published: February 2008

The Goose Bay high‐frequency radar can be operated in a mode that allows the study of the temporal and spatial behavior of pulsating phenomena with a time scale of minutes. On November 28, 1983, an event occurred during which long‐period pulsations were observed in the radar data. At this time, the field of view of the radar included a region of the cleft immediately to the east of the cusp. Combination of the radar data with HILAT magnetometer data had allowed the identification of the regions of the magnetosphere that mapped to the radar field of view. Pulsations with 10‐min and 15‐min periods were seen in a region mapping to the interior of the magnetosphere. They had high azimuthal wave number (17–25) and propagated eastward with a speed greater than 1 km/s. At the same time, eastward drifting patches of backscatter with a similar speed were seen in the region of antisunward convection that mapped either to the solar wind or the low‐latitude boundary layer. A possible interpretation is that antisunward disturbances propagating along the magnetospheric boundary were driving surface waves within the magnetosphere. Possible types of disturbance that could cause such surface waves are flux‐transfer events or Kelvin‐Helmholtz waves.
Solar cycle modulation of galactic protons and electrons
Authors: Perko John S.
Published: February 2008

A solution of the time‐dependent, spherically symmetric cosmic ray transport equation, with a defensible diffusion coefficient and a natural model for an 11‐year cycle of diffusive scattering disturbances that originate on the sun and travel through interplanetary space, accounted simultaneously for the spectral changes of both galactic protons and electrons, for the time and phase lag of high‐ versus low‐energy protons, and for the integral radial gradients of protons > 100 MeV over most of the solar cycle and over large distances in the heliosphere. Each individual disturbance caused a sudden particle intensity decrease as it passed a point in space; recovery of intensity began immediately afterward. The characteristic recovery time at 1 AU was in the range found in neutron monitor and satellite data, except that the recovery time constant was rigidity‐dependent, contrary to these same data. Also, spectral changes over successive solar minima in 1965 and 1977, heretofore linked to drifts, can be explained as an adjunct to the hysteresis effect. Overall, the primary galactic cosmic ray flux over the 11‐year solar cycle is dominated in the ecliptic plane by turbulent scattering regions emitted by the sun and at best only secondarily affected by gradient and curvature drifts, effects which may be confined near 1 AU.
The influence of centrifugal forces on the B field structure of an axially symmetric equilibrium magnetosphere
Authors: Ye Gang , Voigt Gerd‐Hannes
Published: February 2008

We investigate a stationary model of a rotating, axially symmetric “pole‐on” magnetosphere in MHD force balance. In this model both the planet's rotational and dipole axes are aligned with the magnetotail axis, which is the axis of symmetry in a cylindrical (r, ϕ, z) coordinate system. For mathematical convenience the magnetosphere is confined on the nightside by a cylindrical magnetopause with constant radius. On the sunward side, the magnetosphere is closed by an appropriate image dipole. Inside the magnetospheric cavity we assume isotropic thermal plasma pressure. We assume further that, in general, planetary rotation leads to differentially rotating magnetotail field lines causing field‐aligned Birkeland currents and a corresponding toroidal magnetic Bϕ component which leads to twisted magnetotail field lines. We calculate the deformation of magnetotail field lines under the influence of both thermal plasma pressure and centrifugal forces. We present “linear” (analytic) solutions to the Grad‐Shafranov equation which include the centrifugal force term. In the linear model, two free physical parameters, k and ω, measure the plasma thermal pressure and the ratio between plasma rotational and thermal energy densities, respectively. Low ω and high k values indicate the plasma‐dominated case. Conversely, low k and high ω values indicate the rotation‐dominated case. One limiting case, k = ω = 0, generates a simple vacuum magnetic field of a dipole confined within the magnetospheric cavity. The nonrotational magnetosphere with hot thermal plasma leads to a field configuration without a toroidal Bϕ component and without field‐aligned Birkeland currents. The other extreme, namely, a rapidly rotating magnetosphere with cold plasma, leads to a configuration in which the plasma must be confined within a thin disk in a plane where the radial magnetic field component Br vanishes locally. Utmost stretched magnetotail configurations can be achieved by increasing either the plasma thermal pressure or the rotation frequency of the magnetosphere, or both. In the rotation‐dominated case we found the plasma sheet thinner and located closer to the magnetopause than in the purely plasma‐dominated case. This implies that hypothetical polar aurorae, under the influence of magnetospheric rotation, appear at higher magnetic latitudes on both the dayside and the nightside. This also implies that the size of the polar oval shrinks under the influence of magnetospheric rotation. A “pole‐on” magnetosphere can be expected at Uranus in the year 2014 twice during a Uranian day.
Excess bottom radon 222 distribution in deep ocean passages
Authors: Sarmiento J. L. , Broecker W. S. , Biscaye P. E.
Published: February 2008

Radon 222 and STD profiles were obtained as part of the Geosecs program in the Vema Channel in the southwest Atlantic Ocean and in the Samoan, Clarion, and Wake Island passages in the Pacific Ocean. The standing crop of excess radon 222 is higher in the passages than at other nearby locations, The most likely explanation for this is that there is a high flux of radon 222 from the floor of the passages. Since much of the floor is covered with manganese nodules and encrustations, the high flux of radon 222 may be attributable to the high concentrations of radium 226 in the outer few millimeters of such deposits. Laboratory measurements of radon 222 emissivity from manganese encrustations obtained in the Vema Channel support this hypothesis. The excess radon 222 in the Vema Channel and Wake Island Passage is found in substantial quantities at heights above bottom greatly exceeding the heights at which excess radon 222 is found in nonpassage areas. The horizontal diffusion of radon emanating from the walls of the passages is unlikely to be the cause of the observed concentrations because the ratio of wall surface area to water volume is very low. The profiles must therefore be a result of exceptionally high apparent vertical mixing in the passages. Further work is needed to determine the nature of this apparent vertical mixing. The excess radon 222 and STD data in all four passages have been fit with an empirical model in which it is assumed that the buoyancy flux is constant with distance above bottom. The fits are very good and yield apparent buoyancy fluxes that are between 1 and 3 orders of magnitude greater than those obtained at nearby stations outside the passages for three of the four passages.
Air deployment of satellite‐tracked drifters
Authors: Cheney Robert E. , Richardson Philip L. , Blumenthal Barry P.
Published: February 2008

Six free‐drifting buoys tracked by the Nimbus 6 satellite were successfully launched by C‐130 aircraft in a series of deployments during 1977–1979. The buoys were launched in Gulf Stream rings which had been identified with airborne XBT surveys and satellite infrared images. This is the first operational test of these air‐deployable buoys.
Synthetic aperture radar imaging of ocean waves: Comparison with wave measurements
Authors: McLeish William , Ross Duncan , Shuchman Robert A. , Teleki Paul G. , Hsiao S. Vincent , Shemdin O. H. , Brown W. E.
Published: February 2008

Synthetic aperture radar images of ocean waves were obtained in conjunction with reference wave data near Marineland, Florida, December 14, 1975. Each of the various types of measurements were processed into a form that allowed direct comparisons with the others. Maxima of radar spectra occurred at the same frequencies as the maxima of reference wave height spectra. In a comparison of a radar spectrum with observed spectra of wave height, wave orbital velocity, and surface slope the high‐frequency portion of the radar spectrum lay near and between the wave height and the orbital velocity spectra but differed significantly from the surface slope spectrum. The radar‐derived mean directions and model‐fitted directional spreads of wave energy were close to the values from a directional wave buoy and indicated the accuracy of radar measurements of wave direction. However, a directional plot of a radar spectrum near shore at the frequency of the maximum showed a sharper peak than such a plot of a fitted spectrum derived from reference data. The high directional resolution of the radar, in addition to its making observations at different locations, allowed radar images to provide information about ocean waves not available from the other instruments. As a swell propagated across the continental shelf, it was scattered in direction, apparently by the irregularities of the bottom, and very little of its energy reached shore. The shorter sea waves had a narrow directional distribution when first observed offshore that may have been sharpened by interaction with the Gulf Stream. Radar images showed effects of bottom refraction on the sea waves as they moved into progressively shallower water.
Atmospheric injections of nuclear debris: Strontium 89 and 90 from Chinese weapons tests
Authors: Burchfield L. A. , Stevens S. , Inn K. G. W. , Sumerlin N. G. , Kuroda P. K.
Published: February 2008

The concentrations of 89Sr and 90Sr in a total of 455 samples of individual rain and snow collected at Fayetteville (36°N, 94°W), Arkansas, were determined radiochemically during the period between April 1973 and June 1981. Nine atmospheric nuclear tests were conducted by the government of China at Lop Nor (40°N, 90°W) during the period 1973–1981. The Chinese nuclear tests of June 27, 1973 (3‐megaton, the 15th test); June 17, 1974 (1–2 megaton, the 16th); January 23, 1976 (reported to have been a low‐yield device, the 18th); and November 17, 1976 (4‐megaton, the 21st) injected the bulk of the nuclear debris into the stratosphere. The values of mean residence times ranging from 7 to 20 days obtained after the 19th, 22nd, 23rd, and 24th Chinese tests were similar to those reported earlier for the mean residence time of nuclear debris injected into the troposhere. The cycling effect of the nuclear debris was observed after the 22nd Chinese test of September 17, 1977, and the 25th Chinese test of October 16, 1980.
On the frontal speeds of internal gravity surges on sloping boundaries
Authors: Hay Alex E.
Published: February 2008

An expression for the slope dependence of the frontal velocity of an internal gravity surge in deep water is derived from the momentum equations for two‐dimensional, inviscid, steady flow. The effects of bottom friction are incorporated by assuming a universal shape for the head of the surge. The resulting expression is consistent with the slope dependence indicated by existing experimental results for small slopes (<5°–15°). The absolute velocity is not predicted by the theory, however, because an indeterminate parameter appears in the result. Furthermore, the experimental data indicate variations in the dependence of nose velocity on slope which depend upon the parameters of the flow itself. It is also shown that the entrainment constant may be estimated from experimental data at large slopes.
A numerical model of the time‐dependent wintertime circulation of the New York Bight
Authors: Hsueh Y. , Chen K. C. , Marmorino G. O.
Published: February 2008

The time‐dependent flow in the New York Bight from March 7 to April 30, 1975, is calculated from approximations to the barotropic vorticity equation subject to forcing by winds observed at the John F. Kennedy airport and by an upstream flow across the Long Island shelf. Comparisons of major axis velocities to observations throughout the bight show reasonable agreement. There is also considerable model skill in the prediction of alongshore variations in the major axis velocity with relatively low absolute errors. In general, associated with northeastward winds are northeastward shelf flows and upvalley currents in the Hudson Shelf Valley (HSV). Downvalley flows in the HSV occur when the northeastward wind abates and the flow on the shelf turns southwestward. The mechanism responsible for the behavior of the valley flow appears to be topographic steering with moderation due to bottom friction. The time rate of change of relative vorticity does not appear to have large net effect over the duration of an event Consequently, steady state models represent well the dynamics for an event‐averaged flow. Discrepancies between model results and observation suggest that there is indeed a southwestward pressure gradient force operating in the New York Bight, and an adiabatic pressure condition offshore may be an over simplification that need be removed.
Tropospheric methane: Concentrations between 1963 and 1970
Authors: Stephens Edgar R.
Published: February 2008

Previously unpublished measurements of methane concentrations in surface air (1963 to 1970) are reported. The values obtained, which ranged from 1.37 to 1.57 ppm by volume (moles), are consistent with current literature reports of 1.68 ppm in mid‐1982 and an annual increase of just over 1%.
Recent advances in magnetosphere‐ionosphere coupling
Authors: Greenwald R. A.
Published: February 2008

In this review we examine the general approach to studies of magnetosphere‐ionosphere coupling as advocated initially by Vasyliunas and later advanced by the Rice University magnetospheric modeling group. While this problem is inherently quite complex even with simplifying assumptions, the initial results from the International Magnetospheric Study (IMS) have also brought the simplifying assumptions into question. In particular, it has been shown that (1) the assumption of equipotential magnetic field lines may often be invalid, (2) under disturbed (substorm) conditions the existing static magnetic field models may be grossly inaccurate, and (3) under disturbed conditions, energized ionospheric ions may play a significant role in populating the magnetospheric plasma. It is argued that our best hope for advancement in the field of ionosphere‐magnetosphere coupling lies in comparing the various ground‐based and satellite data available from the IMS within the framework of existing analytical and computer models. Comparative analysis is required in order to check the internal self‐consistency of the measured parameters and to test the validity of any simplifying assumptions that might be present in the theoretical developments.
The Evaluation of the Field of the Currents Induced in the Earth by an External Field Whose Distribution is Known Numerically
Authors: Ashour Attia A.
Published: February 2008

The elements of the magnetic field of the currents induced in the earth by an external magnetic field whose distribution is supposed to be known numerically are found in terms of the corresponding elements of the external field. The conductivity of the earth is represented by a uniformly conducting shell of radius qa (q < 1). When the conductivity of the shell is assumed infinite, these relations are Zi(P) = −q3Ze(P″) and Hi(P) = q3He(P″) − (1/qa2) rHe(r) dr, where Z and H are the vertical and vector horizontal components, P is a point on the earth's surface, P′ is a point on the same radius as P and at distance q2a from the earth's center, and r is the radius vector from the center of the earth. When the conductivity of the shell is taken as finite, a correction to the above formulas is given. The formulas are useful in comparing the observed distribution at the surface of the earth with what is to be expected from an external current system, when the effects of induction in the earth are taken into account.
A Linear Analysis of The Formation of Field‐Aligned Striations in Plasma Clouds Due to Cross‐Field Instability
Authors: Rao P. B. , Russell W. H.
Published: February 2008

A weakly ionized plasma with gradients in the ionization density under the influence of the crossed electric and magnetic fields is subject to a unique type of plasma instability called the cross‐field or E×B instability. This paper examines by means of a linear analysis the relevance of such an instability mechanism to the formation of the field aligned columns of enhanced ionization or striations in the artificially generated plasma clouds in the upper atmosphere. A Gaussian model for the electron density distribution in the cloud and the electric fields that have been derived from the ion and neutral cloud drift motions have been used in computing the characteristic parameters, which are the minimum wavelength λmin and the e‐folding growth time τ for the instability. A brief comparison has shown good agreement between the computed instability model and the observed striation formation in one of the high latitude Barium releases conducted in Alaska during March 1969 (test hemlock of Secede III series). Some general results that show the dependence of the instability parameters on the height of the release and cloud dimension are also presented.
Electric Current System in the Undisturbed Magnetospheric Tail
Authors: Hruška A.
Published: February 2008

Satellite measurements of the magnetic field B in the earth's tail indicate the existence of electric currents flowing inside the tail but outside the so‐called ‘Current’ or ‘neutral’ sheet. The Imp 3 data indicate that the density of these currents, although not insignificant, is smaller than the current density inside the ‘neutral’ sheet. Preliminary discussion of the effect of the polarity of the interplanetary magnetic field Bi on the tail geometry is presented. The ‘neutral’ sheet is systematically displaced northward if the polarity of Bi is positive (i.e., if Bi has a component directed away from the sun), but its average position is close to the plane Z = 0 if the polarity of Bi is negative. ((X, Y, Z) is the standard solar magnetospheric coordinate system.) The tail structure outside the ‘neutral’ sheet is not symmetric with respect to the plane Z = 0, even if the geomagnetic latitude of subsolar point (χ) is close to zero; i.e., the magnetic field in the part of the magnetotail where the X component of B is antiparallel to the X component of Bi is smaller than in the other part of the tail.
Propagation Delay in the Atmosphere
Authors: LeVine D. M.
Published: February 2008

Calculations of the propagation delay due to the atmosphere in satellite‐to‐earth communication are reported for the frequency range 1 to 15 GHz. A spherically symmetric, smoothly varying model is assumed for the atmosphere, and the techniques of geometrical optics are employed. The difference between the actual propagation delay and the delay which would occur in free space is presented for the lower atmosphere, the ionosphere, and the composite atmosphere.
The M.I.T. Ku‐Band Radio Interferometer
Authors: Papadopoulos G. D. , Burke B. F.
Published: February 2008

The construction of a Ku‐band radio interferometer and some preliminary observations are reported. The interferometer was built for the purpose of mapping discrete radio sources like the Crab Nebula, Cassiopeia A, and Cygnus A. It has two 8‐ft parabolic antennas operating at 17.128 GHz (1.75 cm). The maximum baseline of 100 m corresponds to a resolution of 35 sec of arc. A PDP‐8 computer is incorporated in the system and is used for pointing, tracking, delay compensation, and real‐time data analysis. The phase stability of the system was better than 10° over a period of 2 hours. Consistent fringe components were obtained from the Crab Nebula with a baseline set at 8 m.
Space‐time analysis of wave propagation through a turbulent medium
Authors: Rumsey V. H.
Published: February 2008

The Kolmogorov hypothesis of an inertial range within the spectrum of steady state turbulence is used to show that the space‐time structure function for the velocity fluctuations in a fluid has the form of (r4/3 + ∈2/3 t2)½ where r and t are the space and time lags and ∈ the energy, for a reference frame in which the mean velocity is zero. The associated space‐time spectra are also derived. Equations for the propagation of the N event space‐time correlation functions of the complex electric field are derived assuming that the width of the angular spectrum of plane waves is much less than a radian.
Effects of anisotropy in inhomogeneous optical fibers
Authors: Parriaux Olivier , Gardiol Fred E. , Decreton Marc C.
Published: February 2008

An approximate computer technique investigates wave propagation along radially inhomogeneous anisotropic fibers. The electromagnetic field components are determined by numerical integration across thin concentric tubes within the fiber core. The continuity of tangential components at the tube boundaries yields a dispersion relation for the propagation constant. The effect of anisotropy on group velocity within multimode graded‐index fibers is determined.
Orthogonality and transmission characteristics of fundamental modes in elliptically cross‐sectioned optical fiber and representation on Poincaré sphere
Authors: Fujii Yoichi
Published: February 2008

The field distribution in the elliptical optical fiber is theoretically analyzed and its polarization stability to the bending and the twist is discussed by using Poincaré sphere representation.
Inversion of data from diffraction‐limited multiwavelength remote sensors: 2. Nonlinear dependence of observables on the geophysical parameters
Authors: Rosenkranz P. W.
Published: February 2008

Linear shift‐invariant spatial filtering is applied to inversion of radiometric measurements of the earth in both polarizations at frequencies of 6.6, 10.7, 18, 21, and 37 GHz. The state of the ocean‐atmosphere system, for the purpose of radiative transfer calculations at these frequencies, is described by a seven‐parameter model. The parameters are sea surface temperature, near‐surface wind speed, integrated water vapor mass, scale height of water vapor in an exponential distribution, integrated liquid water mass, height of the liquid water, and characteristic drop radius in a Best drop size distribution. Nonlinear dependence of brightness temperature on these parameters is approximated by second‐order terms in the parameters. Residual nonlinearity of the system appears theoretically as cross talk from the second‐order terms to the first‐order terms. Given the linear filter structure, the filter coefficients are obtained by minimizing the expected square error, which includes both first‐ and second‐order components of cross talk, noise, and fine‐structure error. The last is the result of incomplete restoration of the geophysical parameter fields. Thus the spatial filter deconvolves and inverts the data simultaneously. The two heights are found not to be recoverable from the measurements, however.
Quantum solid state mechanisms of biological effects of electromagnetic radiation with emphasis on local superconductivity
Authors: Achimowicz J.
Published: February 2008

The aim of the paper is to review quantum solid state mechanisms of nonthermal (specific) bioeffects of nonionizing radiation and to present the author's own hypothesis concerning mechanisms based on biological superconductivity. Classical and quantum mechanisms of bioeffects are compared stressing the necessity of not only considering quantum absorption, transfer, and conversion of radiation energy in biological systems, but also of appropriate systems modeling. The need is stressed for developing quantum models of the biological solid state on the supramolecular level to fill the gap between molecular and cell biology. The supramolecular models of macromolecules and enzyme complexes will be reviewed. The high‐temperature superconductivity problem in organic systems will be discussed with stress on the importance of system structure and the excitation quasi‐particle (phonon and electron) spectra relationship. New mechanisms of enzymatic activity assuming enzyme‐substrate complex electron spectrum instability induced by electron‐ and phonon‐mediated electron‐electron interaction are proposed. Since this quantum cooperative phenomenon is the possible origin of specificity and efficiency of enzyme action it is extremely sensitive to system‐generated electromagnetic fields, which gives the possibility of enzymatic regulation and also may explain some nonthermal resonant bioeffects. Local superconductivity (coherent electron states) and Josephson effects as the possible mechanisms of bioeffects are discussed.
A class of new microwave therapeutic applicators
Authors: Lin James C. , Kantor Gideon , Ghods Abdolhamid
Published: February 2008

A class of new direct‐contact microwave applicators has been developed for diathermy and hyperthermia applications. They consist of three concentric, circular, cylindrical tubes. The inner cylinder may serve as a port for circulating coolant to reduce surface temperature or as a port for introducing ionizing radiation in combination therapy for cancer. The coaxial waveguides formed by the inner and middle cylinders and by the middle and outer cylinders permit the propagation of TE11 and TE21 modes, respectively, for dual‐beam, single‐frequency use. The combinations give relatively uniform, circularly symmetric heating distributions in the tissue. Heating pattern and leakage level measurements obtained for a 10‐cm‐diameter dual‐beam 2450±50‐MHz applicator show that the maximum leakage level at a distance of 5 cm from the surface of the applicator in contact with planar fat‐muscle phantoms is less than 4 mW/cm2 for a therapeutic specific absorption rate (SAR) of 235 W/kg. This value corresponds to a net forward power of 26 W. The measured VSWR is about 1.25. The width of the heating pattern is about 4 cm at a depth of 2.2 cm into the simulated muscle, where the SAR is half the maximum, and decreases slowly as the depth into the muscle increases, thus giving it a fairly uniform distribution.
Implantable microwave radiators for clinical hyperthermia
Authors: Taylor Leonard S. , Samaras George M. , Cheung Augustine Y. , Salcman Michael , Scott Ralph M.
Published: February 2008

We describe the design of coaxial microwave radiators suitable for localized hyperthermia of neoplasia in the esophagus, brain, and other organs which are accessible through body orifices. These radiators can be implanted surgically and are small enough to be passed through such devices as nasogastric tubes and bronchoscopes. The radiators consist of combinations of cross‐switched half‐wavelength coaxial sections and/or needle antenna terminations. The performance of these radiators, as determined by thermogram recordings in tissue phantoms and the results of in vivo animal tests, is described.
Impedance conditions for a coated cylindrical conductor
Authors: Wait James R.
Published: February 2008

We present an analysis for the electromagnetic response of a cylindrical conductor of infinite length which has a uniform coating. We show that subject to the thinness of the coating, an approximate spatially dispersive boundary condition can be developed which holds in a general context.
Preliminary note on an “international magnetic standard”
Authors: Bauer L. A.
Published: February 2008

The intercomparisons of magnetic instruments made by the various investigators during the past fifteen to twenty years have served to call attention to the discrepancies existing between the determination of the magnetic elements by various observatory and magnetic survey instruments. These discrepancies frequently exceed the errors of observation. At the recent meeting of the International Meteorological Conference held at Innsbruck in 1905, renewed consideration was given this important matter by its Committee on Terrestrial Magnetism.

The extensive magnetic operations of the Carnegie Institution of Washington have necessitated giving the adoption of an “International Standard” correct to within at least the allowable error of field observations early consideration. In the course of the work thus far executed, comparisons have been obtained between the following magnetic observatories: Cheltenham (Maryland), Toronto ‐ Agincourt (Canada), Baldwin (Kansas), Mexico (Mexico), Havana (Cuba), Sitka (Alaska), Honolulu (Hawaii), Apia (Samoa), Tokio (Japan), Zi‐ka‐wei (China), Hongkong (China), Christchurch (New Zealand, Sydney and Melbourne (Australia). Further comparisons will be obtained in 1908–9 in Europe, Africa and Asia in the course of magnetic work to be executed during this period.
Determination of the horizontal intensity of the Earth's magnetic field by means of the discharge from the Wehnelt cathode
Authors: Knipp C. T. , Welo L. A.
Published: February 2008

A common method of determining the ratio of the charge to the mass of an electron is to use a cathode discharge tube and measure the deflection of the beam of particles by a magnetic field; the other necessary relation being obtained, either by observing the fall of potential at the cathode, or the deflection of the rays as they pass between the plates of a condenser.
Sur le champ électrique de l'atmosphère à Rio de Janeiro
Authors: Morize Par H.
Published: February 2008

Depuis longtemps déjà, des tentatives ont été faites à l'Observatoire de Rio de Janeiro, dans le but d'obtenir des données continues sur le potentiel électrique de l'atmosphère; mais, par suite de ressources insuffisantes, aussi bien en matériel qu'en personnel, les résultats obtenus n'ont servi qu'à montrer les difficultés à vaincre.

Ce n'est qu'en 1909, après l'acquisition d'un électromètre enregistreur de Benndorf et d'un disque radioactif Armet de Lisle, que les observations régulières ont pû commencer. Les difficultés rencontrées ont été tout d'abord le manque d'une place appropriée et l'inconstance de l'isolement, due à l'élévation du degré hygrométrique de l'air, et à de petites araignées qui établissent des courts‐circuits difficiles à localiser. Une autre cause, heureusement peu fréquente, provient de petites étincelles qui passent de la borne d'entrée à la caisse extérieure de l'appareil, quand, durant des orages, le potentiel devient très élevé. Ces étincelles lèchent la surface de l'isolateur d'ambre et laissent une couche d'oxyde presqu'invisible, qui lui fait perdre ses qualités isolantes, jusqu'à ce qu'un nettoyage complet l'ait enlevée.
The magnetic character of the year 1928
Authors: van Dijk G.
Published: February 2008

Forty‐one observatories have collaborated in establishing the magnetic character of the year 1928. The lists for Kakioka have no longer been received and at Munich registration of the magnetic variations was interrupted at the beginning of the year on account of the disturbances caused by electric tramlines. Observations are lacking for San Juan for January and September, for Vassouras during the greater part of January and December and for several days in the other months. The Observatory of Buitenzorg was replaced in November by the new observatory at Kuiper, an island in the Bay of Batavia.
Atmospheric potential‐gradient results at Cebu during solar eclipse, May 9, 1929
Authors: Deppermann C. E.
Published: February 2008

The accompanying figure is a reproduction of the atmospheric‐electric curves taken with the Wulf electrometer of the Weather Bureau, Central Office, Manila, at Sogod, Cebu, Philippine Islands, on the day of the total eclipse of the Sun, May 9, 1929, together with the two curves for the days preceding.

First contact was calculated as 14h 10m 29s and was correct practically to the second; totality began at 15h 29m 47s and lasted for 3 minutes and 38 seconds; last contact was at 16h 42m 7s.
Cheltenham Magnetic Observatory July to September, 1940
Authors: Ludy Albert K.
Published: February 2008

July 13–14—A storm began at 08h 00m GMT, July 13, and ended at 08h, July 14. The elements were very active between 11h 52m and 15h, July 13. Ranges: D, 26′; H, 215 gammas; Z, 50 gammas.
The Kernel function of linear nonstationary surface runoff systems
Authors: Diskin M. H. , Boneh A.
Published: February 2008

Adopting a linear nonstationary model for the surface runoff system gives a better fit to a set of observed direct surface runoff hydrographs than adopting a stationary linear model. The kernel of this model, which is a function of two time variables, can be considered to be an assembly of impulse response functions for unit pulses acting at various time intervals after the beginning of the storm. Each of these impulse response functions must have the properties of an ordinary instantaneous unit hydrograph. The kernel function is evaluated by an optimization procedure that seeks to minimize the sum of squared deviations between the observed and computed hydrographs for a number of independent storms, subject to given constraints. The procedure is based on a discretization scheme for the functions involved. The set of equations for the unknown kernel values can be partitioned into independent subsets, each of which is solved individually. The complete equation set need be considered only when area constraints of the kernel function are imposed.
Dependence of size distribution for liquid cluster ions on retarding voltage
Authors: Takaoka Gikan H. , Okada Takeshi , Sugiyama Kazumichi , Kawashita Masakazu
Published: January 2008

We have succeeded in producing liquid clusters such as ethanol and water clusters by an adiabatic expansion phenomenon, and the cluster size distribution was analyzed by using the time-of-flight method. For ethanol cluster ions, the size was distributed between a few hundreds and a few thousands, and the peak size was approximately 1200molecules per cluster. For water cluster ions, the size distribution shifted to higher values, and the peak size was approximately 2500molecules per cluster. Furthermore, the cluster size distribution was measured by changing the retarding voltage, and it was found that the minimum size increased with increase of the retarding voltage. In addition, the minimum size was larger than the critical size estimated by the theoretical calculation.
Demonstration of a multiplexer of dissipationless superconducting quantum interference devices
Authors: Mates J. A. B. , Hilton G. C. , Irwin K. D. , Vale L. R. , Lehnert K. W.
Published: January 2008

We report on the development of a microwave superconducting quantum interference device (SQUID) multiplexer to read out arrays of low-temperature detectors. In this frequency-division multiplexer, superconducting resonators with different frequencies couple to a common transmission line and each resonator couples to a different dissipationless SQUID. We demonstrate multiple designs, with high-Q values (4100–18 000), noise as low as 0.17μΦ0∕Hz, and a naturally linear readout scheme based on flux modulation. This multiplexing approach is compatible with superconducting transition-edge sensors and magnetic calorimeters and is capable of multiplexing more than a thousand detectors in a single transmission line.
Microwave spectrum of the HD2O+ ion: Inversion-rotation transitions and inversion splitting
Authors: Furuya Takashi , Saito Shuji
Published: January 2008

Inversion-rotation spectral lines of the dideuterated hydronium ion, HD2O+, have been observed by a source-modulation millimeter- to submillimeter-wave spectrometer. The ion was generated by a hollow-cathode discharge in a gas mixture of D2O and H2O in a free-space cell. Ten inversion-rotation lines were measured precisely for the lowest pair of inversion doublets in the frequency region from 380to730GHz. The observed lines include the most astronomically important transitions, 000−−110+ for the para species at 380538.031(32)MHz and 101−−111+ for the ortho species at 728420.189(34)MHz, which could be used as a radio astronomical probe investigating interstellar chemistry of deuterium fractionation. An analysis of the measured lines has yielded the rotational constants in the ground doublet states and the inversion splitting. The inversion splitting in the ground state was determined to be 808866(34)MHz, that is, 26.98087(113)cm−1, where the numbers in parentheses give uncertainties estimated from the Jacobian matrix of the assumed centrifugal distortion constants. The determined inversion splitting is off by −0.51cm−1 from the predicted value of 27.49cm−1 by Rajamäki et al. using high-order coupled cluster ab initio calculation [J. Chem. Phys. 118, 10929 (2003)], and by −0.0510cm−1 from the observed value of 27.0318(72)cm−1 by Dong et al. using high-resolution jet-cooled infrared spectroscopy [J. Chem. Phys. 122, 224301 (2005)] beyond the quoted uncertainty.
Self-gravitational instability of rotating anisotropic heat-conducting plasma
Authors: Prajapati R. P. , Parihar A. K. , Chhajlani R. K.
Published: January 2008

The self-gravitational instability of rotating anisotropic heat-conducting plasma with modified Chew–Goldberger–Low equations is investigated. The general dispersion relation is obtained using normal mode analysis by constructing the linearized set of equations. This dispersion relation is further reduced for propagation parallel and perpendicular to the direction of magnetic field. These conditions are discussed for axis of rotation along and perpendicular to the magnetic field. It is found that the heat flux vector does not influence the transverse mode of propagation for both cases of rotation and Jeans condition remains unchanged. In case of propagation parallel to the magnetic field with axis of rotation perpendicular to the magnetic field, we get the dispersion relation, which shows the joint effect of rotation and heat flux vector. The two separate modes of propagation are obtained in terms of rotation and heat flux vector for rotation parallel to the magnetic field. It is demonstrated that the Alfvén wave and the associated firehose instability are not affected by the presence of heat flux corrections and rotation also. The numerical analysis is performed to show the effect of rotation, pressure anisotropy, and heat flux parameter on the condition of instability in the spiral arms of galaxy. The Jeans condition of gravitational instability is obtained for both the cases of propagation.
The structures and magnetic properties of Ti-substituted Pr2(Fe,Co)14(C,B)-type nanocomposites
Authors: Li A. H. , Li W. , Chiu C. H. , Chang H. W. , Chang W. C. , Yue M.
Published: January 2008

The phase evolution, microstructure, and magnetic properties of PrxFe80−xTi2Co10B4C4 (x=9,10.5) melt-spun ribbons were studied. All these ribbons consist mainly of three phases, namely, 2:14:1, α-(Fe,Co), and 2:17 phases. The Hci significantly increases and Br slightly decreases with increasing Pr content. It was found that increasing Pr content from 9to10.5at.% leads to marked grain refinement in the ribbons. Increasing Pr content also helps suppress the formation of metastable 2:17 phase and the grain growth of the α-(Fe,Co) phase during the annealing treatment, thus avoiding the formation of extensive soft magnetic regions. The refined and uniform structure tends to enhance the exchange-coupling interaction between magnetic grains, which results in a significant improvement of the demagnetization-curve shape and magnetic properties accordingly. High coercivity Hci of 10.2kOe, remanence Br of 9.6kG, and maximum energy product (BH)max of 17.4MGOe have been achieved in Pr10.5Fe69.5Ti2Co10B4C4 ribbons after optimal annealing.