bluuebunny/crossref_metadata_2025 huggingface dataset:
Explanatory models of addictive behaviour among native German, Russian-German, and Turkish youth
Authors: Penka S. , Heimann H. , Heinz A. , Schouler-Ocak M.
Published: March 2008

In Germany, the public system of addiction treatment is used less by migrants with addictive disorders than by their non-migrant counterparts. To date, the literature has focused primarily on language, sociocultural factors, and residence status when discussing access barriers to this part of the health care system. However, little attention has been paid to cultural differences in explanatory models of addictive behaviour. This is surprising when we consider the important role played by popular knowledge in a population's perceptions of and responses to illnesses, including their causes, symptoms, and treatment.

In the present study, we examined explanatory models of addictive behaviour and of mental disorders in 124 native German und Russian-German youth and compared these models to those observed in an earlier study of 144 German and Turkish youth. We employed the free listing technique German and to compile the terms that participating subjects used to describe addictive behaviour. Subsequently, we examined how a subset of our study population assigned these terms to the respective disorders by means of the pile sort method.

Although the explanatory models used by the German and Russian-German youth in our study were surprisingly similar, those employed by Turkish youth did not make any fundamental distinction between illegal and legal drugs (e.g. alcohol and nicotine). German and Russian-German youth regarded eating disorders as “embarrassing” or “disgraceful”, but Turkish youth did not. Unlike our German and Russian-German subjects, the Turkish youth did not classify eating disorders as being addictive in nature. Moreover, medical concepts crucial to a proper understanding of dependence disorders (e.g. the term “physical dependence”) were characterised by almost half of our Turkish subjects as useless in describing addictions.

These findings show that it is impossible to translate medical or everyday concepts of disease and treatment properly into a different language without considering the connotations and implications of each term as it relates to the respective culture. Terms that are central to Western medical models of disease may otherwise be misunderstood, misinterpreted, or simply rejected.
A many-body force decomposition with applications to flow about bluff bodies
Authors: CHANG CHIEN-C. , YANG SHIH-HAO , CHU CHIN-CHOU
Published: March 2008

The study presents a force theory for incompressible flow about several solid bodies, which enables us to examine the force contribution to each body from individual fluid elements. By employing auxiliary potential functions, we decompose hydrodynamic forces in terms of the unsteadiness of the incoming stream, vorticity within the flow, and surface vorticity on the solid bodies. The usefulness of this force decomposition is illustrated by examining separated flow about several circular cylinders. Guidelines were obtained for finding an optimal arrangement to achieve significantly small drag exerted on the cylinders.
A sphere in a uniformly rotating or shearing flow
Authors: BLUEMINK J. J. , LOHSE D. , PROSPERETTI A. , VAN WIJNGAARDEN L.
Published: March 2008

It is known that, in a linear shear flow, fluid inertia causes a particle to spin more slowly than the surrounding fluid. The present experiments performed with a sphere with fixed centre, but free to rotate in a fluid undergoing solid-body rotation around a horizontal axis indicate that the spin rate of the sphere can be larger than that of the flow when the sphere is sufficiently far from the axis. Numerical simulations at Reynolds number 5≤Re≤200 confirm this observation. To gain a better understanding of the phenomenon, the rotating flow is decomposed into two shear flows along orthogonal directions. It is found numerically that the cross-stream shear has a much stronger effect on the particle spin rate than the streamwise shear. The region of low stress at the back of the sphere is affected by the shear component of the incident flow. While for the streamwise case the shift is minor, it is significant for cross-stream shear. The results are interpreted on the basis of the effect of the shear flow components on the quasi-toroidal vortex attached in the sphere's near wake. The contributions of streamwise and cross-stream shear to the particle spin can be linearly superposed forRe=20 and 50.
Seismic and geodetic insights into magma accumulation at Katla subglacial volcano, Iceland: 1999 to 2005
Authors: Sturkell Erik , Einarsson Páll , Roberts Matthew J. , Geirsson Halldór , Gudmundsson Magnús T. , Sigmundsson Freysteinn , Pinel Virginie , Guðmundsson Gunnar B. , Ólafsson Halldór , Stefánsson Ragnar
Published: March 2008

Katla is one of Iceland's most active volcanoes with at least 20 eruptions in the last 1100 years. The volcano is covered mostly by the Mýrdalsjökull ice cap; consequently, Katla eruptions are phreato‐magmatic and are capable of producing jökulhlaups. A jökulhlaup in July 1999, preceded by an episode of continuous seismic tremor, was the first sign of renewed magma movement under the volcano since 1955. Using seismic and geodetic observations, and insights into geothermal activity from ice‐surface observations, we analyze this period of unrest and assess the present state of Katla volcano. From 1999 to 2004, GPS measurements on nunataks exposed on the caldera edge revealed steady inflation of the volcano. Our measurements show uplift and horizontal displacement of the nuntatak benchmarks at a rate of up to 2 cm a−1, together with horizontal displacement of far‐field stations (>11 km) at about 0.5 cm a−1 away from the caldera centre. Using a point‐source model, these data place the center of the magma chamber at 4.9 km depth beneath the northern part of the caldera. However, this depth may be overestimated because of a progressive decrease in the mass of the overlying ice cap. The depth may be only 2–3 km. About 0.01 km3 of magma has accumulated between 1999 and 2004; this value is considerably less than the estimated 1 km3 of material erupted during the last eruption of Katla in 1918. Presently, rates of crustal deformation and earthquake activity are considerably less than observed between 1999 and 2004; nonetheless, the volcano remains in an agitated state.
Lava penetrating water: Submarine lava flows around the coasts of Pico Island, Azores
Authors: Mitchell Neil C. , Beier Christoph , Rosin Paul L. , Quartau Rui , Tempera Fernando
Published: March 2008

Bathymetry data collected with a multibeam echo sounder around Pico Island, Azores (Portugal), reveal a remarkable series of lava flows on the island's shelf with a variety of pristine structures that suggest how lava behaves on entering water. Many flows are dendritic in plan view, some with channels and tumuli. Dendritic geometries are interpreted to arise from flow fronts repeatedly arrested by enhanced cooling and magma pressure subsequently causing new breakouts. Cascades of elongated flow fingers also occur, with individual fingers of comparable diameters to the largest known megapillows. Some flows have wide transverse clefts, in cases separating flows into segments, which are interpreted as caused by their upper surfaces having solidified, while their still‐fluid cores allowed the surfaces to extend. A number of flows moved onto the shelf as large bodies, stopped, and then sourced smaller lobes forming the dendritic patterns. This two‐stage evolution and the tumuli (which lie on a low gradient immediately below a steep nearshore gradient) suggest that, after initial emplacement and development of a crust by cooling, some flows pressurized. Once movements ceased and viscous stresses dissipated, magma static pressure developed from the weight of flow interiors passing over cliffs and nearshore gradients. One group of flows traverses the island's submarine slope, so direct supply of lava to the slopes is possible, although volumetrically how important it is to the island's internal composition is difficult to tell from these data. On the basis of observed strong surf erosion of historical flows, these delicate structures probably could not have survived passage through a moving sea level unmodified by erosion so they are unlikely to be pre‐Holocene subaerial flows. They are interpreted to have formed in the Holocene from flows penetrating sea level or possibly some from nearshore tube openings or vents. Such flows and abundant clastic deposits are ephemeral features that become remobilized by surf during times of lower sea level. The shelves of active volcanic islands are therefore active geologically and are far from being simple products of erosional truncation as was once envisaged.
Monitoring frictional strength with acoustic wave transmission
Authors: Nagata Kohei , Nakatani Masao , Yoshida Shingo
Published: March 2008

We monitored acoustic transmissivity of a frictional interface during laboratory experiments where complex slip history was imposed. Frictional strength, which was also tracked continuously, showed complex changes due to various causes such as aging of the interface in quasi‐stationary contact and slip weakening that began with miniscule pre‐failure slip. Albeit such complexity, acoustic transmissivity was found to be a unique function of frictional strength throughout the experiment. This suggests that acoustic transmissivity reflects the resultant changes in load‐supporting contact population that governs the frictional strength of the moment, not the external conditions that have altered contact state. This simple non‐destructive acoustic measurement, which can be applied remotely and continuously, is therefore a robust technique to monitor frictional strength.
A new technique for retrieval of tropospheric and stratospheric ozone profiles using sky radiance measurements at multiple view angles: Application to a Brewer spectrometer
Authors: Tzortziou Maria , Krotkov Nickolay A. , Cede Alexander , Herman Jay R. , Vasilkov Alexander
Published: March 2008

This paper describes and applies a new technique for retrieving diurnal variability in tropospheric ozone vertical distribution using ground‐based measurements of ultraviolet sky radiances. The measured radiances are obtained by a polarization‐insensitive modified Brewer double spectrometer located at Goddard Space Flight Center, in Greenbelt, Maryland, USA. Results demonstrate that the Brewer angular (0–72° viewing zenith angle) and spectral (303–320 nm) measurements of sky radiance in the solar principal plane provide sufficient information to derive tropospheric ozone diurnal variability. In addition, the Brewer measurements provide stratospheric ozone vertical distributions at least twice per day near sunrise and sunset. Frequent measurements of total column ozone amounts from direct‐sun observations are used as constraints in the retrieval. The vertical ozone profile resolution is shown in terms of averaging kernels to yield at least four points in the troposphere–low stratosphere, including good information in Umkehr layer 0 (0–5 km). The focus of this paper is on the derivation of stratospheric and tropospheric ozone profiles using both simulated and measured radiances. We briefly discuss the necessary modifications of the Brewer spectrometer that were used to eliminate instrumental polarization sensitivity so that accurate sky radiances can be obtained in the presence of strong Rayleigh scattering and aerosols. The results demonstrate that including a site‐specific and time‐dependent aerosol correction, based on Brewer direct‐sun observations of aerosol optical thickness, is critical to minimize the sky radiance residuals as a function of observing angle in the optimal estimation inversion algorithm and improve the accuracy of the retrieved ozone profile.
Trends in the temperature and water vapor content of the tropical lower stratosphere: Sea surface connection
Authors: Rosenlof Karen H. , Reid George C.
Published: March 2008

The tropical lower stratosphere is an important region of the atmosphere, where strong convective activity in the underlying troposphere affects both its chemical and dynamical properties. Temperatures near the tropopause influence the input of water vapor from the troposphere and act as an indicator of the dynamical properties of the region. This paper addresses long‐term trends in the temperature of the tropical lower stratosphere. Correlations with recent changes in tropical stratospheric water vapor are also noted. Special attention is given to the convectively active tropical western Pacific Ocean, where sea surface temperatures (SSTs) are among the highest in the world. The region contains several island radiosonde stations with records reliably extending over several decades. Results show only weak cooling trends occurred before the 1990s, but a strong and rapid cooling of 4° to 6°C took place in the mid‐1990s and has persisted since that time. The properties of the temperature records during and following this cooling event are discussed, and a significant anticorrelation with SST anomalies in the underlying ocean is noted. The rate of ocean warming increased in the early 1990s, coinciding approximately with the mid‐decade cooling event, while individual monthly anomalies in both time series are also anticorrelated. Past work has shown that cooling of the tropical lower stratosphere is a dynamical result of tropospheric convection, which in turn partially depends upon sea surface temperatures. Convection may therefore be the link between the ocean and the stratosphere, and the increased cooling may be an indication of strengthening tropical convection.
Evaluation of real‐time PM2.5 forecasts and process analysis for PM2.5 formation over the eastern United States using the Eta‐CMAQ forecast model during the 2004 ICARTT study
Authors: Yu Shaocai , Mathur Rohit , Schere Kenneth , Kang Daiwen , Pleim Jonathan , Young Jeffrey , Tong Daniel , Pouliot George , McKeen Stuart A. , Rao S. T.
Published: March 2008

The performance of the Eta‐Community Multiscale Air Quality (CMAQ) modeling system in forecasting PM2.5 and chemical species is assessed over the eastern United States with the observations obtained by aircraft (NOAA P‐3 and NASA DC‐8) and four surface monitoring networks (AIRNOW, IMPROVE, CASTNet and STN) during the 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) study. The results of the statistical analysis at the AIRNOW sites show that the model was able to reproduce the day‐to‐day and spatial variations of observed PM2.5 and captured a majority (73%) of PM2.5 observations within a factor of 2, with normalized mean bias of −21%. The consistent underestimations in regional PM2.5 forecast at other networks (IMPROVE and STN) were mainly due to the underestimation of total carbonaceous aerosols at both urban and rural sites. The significant underestimation of the “other” category, which predominantly is composed of primary emitted trace elements in the current model configuration, is also one of the reasons leading to the underestimation of PM2.5 at rural sites. The systematic overestimations of SO42− both at the surface sites and aloft, in part, suggest too much SO2 cloud oxidation due to the overestimation of SO2 and H2O2 in the model. The underestimation of NH4+ at the rural sites and aloft may be attributed to the exclusion of some sources of NH3 in the emission inventory. The systematic underestimations of NO3− may result from the general overestimations of SO42−. Note that there are compensating errors among the underestimation of PM2.5 species (such as total carbonaceous aerosols) and overestimation of PM2.5 species (such as SO42−), leading to generally better performance of PM2.5 mass. The systematic underestimation of biogenic isoprene (by ∼30%) and terpene (by a factor of 4) suggests that their biogenic emissions may have been biased low, whereas the consistent overestimations of toluene by the model under the different conditions suggest that its anthropogenic emissions might be too high. The contributions of various physical and chemical processes governing the distribution of PM2.5 during this period are investigated through detailed analysis of model process budgets using the integrated process rate (IPR) analysis along back trajectories at five selected locations in Pennsylvania and Georgia. The results show that the dominant processes for PM2.5 formation and removal vary from the site to site, indicating significant spatial variability.
Inference Generation During Discourse and Its Relation to Social Competence: An Online Investigation of Abilities of Children With and Without Language Impairment
Authors: Ford Janet A. , Milosky Linda M.
Published: March 2008

Purpose

This study examined whether young children with typical language development (TL) and children with language impairment (LI) make emotion inferences online during the process of discourse comprehension, identified variables that predict emotion inferencing, and explored the relationship of these variables to social competence.

Method

Preschool children (16 TL and 16 LI) watched narrated videos designed to activate knowledge about a particular emotional state. Following each story, children named a facial expression that either matched or did not match the anticipated emotion. Several experimental tasks examined linguistic and nonlinguistic abilities. Finally, each child’s teacher completed a measure of social competence.

Results

Children with TL named expressions significantly more slowly in the mismatched condition than in the matched condition, whereas children with LI did not differ in response times between the conditions. Language and vocal response time measures were related to emotion inferencing ability, and this ability predicted social competence scores.

Conclusion

The findings suggest that children with TL are inferring emotions during the comprehension process, whereas children with LI often fail to make these inferences. Making emotion inferences is related to discourse comprehension and to social competence in children. The current findings provide evidence that language and vocal response time measures predicted inferencing ability and suggest that additional factors may influence discourse inferencing and social competence.
Pressure and Temperature Dependence of the Fe57 Nuclear Magnetic Resonance Frequency in Ferromagnetic Iron
Authors: Benedek G. B. , Armstrong J.
Published: March 2008

We have measured the pressure dependence of the Fe57 nuclear magnetic resonance frequency ν in ferromagnetic iron from 1–10 000 kg/cm2 at −77°C, 0°C, and 84.2°C. From these measurements the volume dependence of ν has been obtained, enabling us to correct measurements of ν(T)P = 1 atm for the effects of thermal expansion. By making a similar correction for the effect of thermal expansion on the temperature dependence of the saturation magnetization σ, we have found that, at constant volume, the hyperfine coupling constant A in the relation ν = Aσ is an explicit function of the temperature. Thus, measurements of the temperature dependence of ν, even when corrected to constant volume, do not give accurately the temperature dependence of σ. The results of a theory based on Stoner's collective electron model for the delectrons are presented to account for the temperature dependence of A.
Excitation and Boundary Effects in Spin-Wave Resonance
Authors: Soohoo R. F.
Published: March 2008

Using the general spin-wave dispersion relation and the general exchange boundary condition, the spin-wave absorption spectrum in a Permalloy film is calculated. Whereas the spacings between the various spin-wave resonance peaks are largely dependent upon the value of the exchange constant A, the result of the calculation shows that the relative intensities of the absorption peaks are dependent upon both A and the surface anisotropy energy density Ks. Thus, the value of Ks can be obtained by comparing the relative experimental intensities of the various peaks with the calculated results using various values of assumed Ks. Though the resonance intensities are also dependent upon the ratio of the rf magnetic fields at the two surfaces of the film, an experimental configuration may be devised such that the ratio of the two fields is near unity. In this way, |Ks| for Permalloy films was estimated to be from 1 to 3 erg/cm2.
Exchange Anisotropy in Oxidized Iron-Cobalt Particles
Authors: Darnell F. J.
Published: March 2008

Oxidized single-domain particles of iron-cobalt were found to exhibit properties characteristic of an exchange interaction between ferromagnetic and antiferromagnetic phases. After cooling in a magnetic field,the normal hysteresis loop was shifted along the magnetization axis. Rotational hysteresis and torque values show maxima with increasing field and indicate effective unidirectional fields of ∼20000 oe. The data are consistent with an exchange model similar to that of Meiklejohn and Bean, but the exchange and antiferromagnetic anisotropy fields are larger than those found for the Co-CoO system.
Crystal Lattice Investigation of the Permanent Magnet Precipitate in Various Alnico Materials
Authors: Kronenberg K. J.
Published: March 2008

Transmission electron diffraction has been applied to study the crystal lattices of various Alnico materials. The method seems to be accurate enough to determine quantitatively the differences in lattice parameters of different Alnico materials in the as-cast state. During the technical heat treatment a phase precipitates which has a lattice parameter of 2.88±0.03 A. Within the limits of error we found this parameter uniform for all investigated Alnico alloys in spite of their different original composition. Surprisingly, this even includes Alnico VIII, which contains 34% Co, 7.5% Al, 14.4% Ni, 4.5% Cu, 5.0% Ti, balance Fe. The different magnetic properties of different Alnico magnets are correlated to the mosaic structure and the degree of ordering achieved by the precipitated phase. These factors vary considerably for the different Alnico materials as electron diffraction reveals. In Alnico V, particularly in the grade with columnar crystal growth (energy product above 7×106 gauss oe), the precipitate appears to have developed into a network extending continuously throughout the magnet body displaying single-crystal order.
Temperature Dependence of Magnetostriction and Anisotropy in MnBi
Authors: Albert P. A. , Carr W. J.
Published: March 2008

Measurements were made of the magnetostriction and anisotropy in oriented polycrystals of MnBi at various temperatures between 77–300°K. The magnetostriction constants in a four-constant expression have been evaluated as a function of temperature, and the first three anisotropy constants also have been estimated. At least at the lower temperatures, it is found that all three constants are necessary to fit the anisotropy data.
Studies of a High-Coercivity Electrodeposit Having a Lamellar Structure
Authors: Sallo J. S. , Olsen K. H.
Published: March 2008

A cobalt-nickel-phosphorus electrodeposit having a 60-cycle coercive force of 1000 oe has been studied. Electron micrographs of the surface indicate that a lamellar structure is present. The lamellas occur in oriented clusters. Diffraction and magnetic studies show the material to be hexagonal with its uniaxial easy direction of magnetization (c axis) in the plane of the film. A Bitter pattern technique utilizing the high resolving power of the electron microscope shows that in a demagnetized sample, fields leave the plane of the film at lamellas cluster boundaries. In a magnetized sample, no fields leave the plane of the film.Studies of cross sections confirm the existence of the lamellar cluster structure. The results are explained on the basis of a model which considers each lamella to be a single-domain particle.
Neutron Diffraction by Helical Spin Structures
Authors: Koehler W. C.
Published: March 2008

This is the summary of a paper which discussed neutron diffraction techniques as applied to helical type and related spin structures, and illustrated these techniques with results from recent investigations on MnAu2 and metallic holmium.
Temperature Dependence of Spontaneous Magnetization in Superparamagnetic Nickel
Authors: Abeledo Carlos R. , Selwood P. W.
Published: March 2008

The possibility of an anomalous temperature dependence of the spontaneous magnetization of superparamagnetic particles has been the subject of several investigations which are in contradiction. We have investigated nickel particles in the 30–100 A diameter range. These were prepared on silica gel supports in the manner familiar in contact catalysis. The spontaneous magnetization in these small particles is slightly but measurably lower than that of massive nickel. The calculated Curie temperature of a sample with average particle diameter of 30 A was about 565°K. It proved impossible to confirm the large variations of Curie temperature, strongly dependent on particle size reported recently for similar preparations.
Angular Variation of the Magnetic Properties of Partially Aligned γ-Fe2O3 Particles
Authors: Bate G.
Published: March 2008

Using a torsion balance magnetometer, measurements have been made on oriented particles of γ-Fe2O3covering a range of packing densities (5%–60%). Microscope examination revealed that the specimens consisted essentially of long chains of particles, parallel to the orientating field, with varying degrees of cross linkages. Measurements were made as a function of the angle between the direction of the orienting field and the direction of the measuring field. The graphs of Hc (the coercivity) versus angle showed a characteristic peak at about 50° while Hr (the remanence coercivity) has its highest value at 90° to the chains and decreases with decreasing angle. Thus, the samples showed their lowest value of Hc and highest value of Hrat 90° to the chains. Torque curves for clockwise and counter-clockwise rotation were obtained as a function of applied field. From these the rotational hysteresis was calculated and gave the maximum anisotropy field at 2500 oe for each specimen. The integral ∫0∝W/Isd(1/H) was evaluated as 1.6 for the 20% specimen.
Coherent and Incoherent Magnetization Processes in Powders
Authors: Shtrikman S. , Wohlfarth E. P.
Published: March 2008

The magnetic properties of a random assembly of uniaxial noninteracting particles are considered on the basis of two extreme mechanisms of irreversible magnetization changes: (a) coherent, and (b) completely incoherent reversals. The bulk properties are determined as weighted averages, the weighting factor f(H0)corresponding to the variation of the critical field H0. Special integral expressions involving the bulk properties are independent of f, and may thus be used to differentiate between the mechanisms (a) and (b). Methods are suggested for determining f from the field dependence of the properties considered. An approximate criterion for neglecting particle interaction in this analysis is given.
Magnetic Anisotropy of Yttrium Iron Garnet at 0°K
Authors: Walker L. R.
Published: March 2008

It is suggested that the discrepancy between the observed rf cubic anisotropy constant K1 of yttrium iron garnet at 0°K and that predicted from the measurement of the crystal fields at octahedral and tetrahedral sites is to be ascribed to the zero point motion of the ferrimagnetic ground state.
Magnetocrystalline Anisotropy of Fe-Si Alloy Crystals under Hydrostatic Pressure
Authors: Kouvel J. S. , Wilson R. H.
Published: March 2008

Magnetization measurements at room temperature were made for various fields applied in 〈100〉, 〈110〉,and 〈111〉 directions of 6 at. % Si in Fe alloy crystals subjected to hydrostatic pressures up to 5100 bar. All the experimental results are found to agree closely with theoretical curves computed for K1−1(∂K1/∂p) = −60, K2−1(∂K2/∂p) = 0, and σ3−1(∂σ3/∂p) = −5.5 (all in 10−7 bar−1), where the anisotropy constants K1 and K2are 46 and 7 (in 103 erg/g), respectively, and the saturation moment σ3, is 204 emu. These values for the pressure dependences of K1 and σ3, when converted to volume dependences and combined with thermal dilatation data, can account for some but only a small part of the discrepancy between recent measurements on this alloy and the theoretical l0th-power relation between the variations of K1 and σ3 with temperature. A similar situation is shown to obtain for pure iron.
Measurements of the Domain Wall Area-Mobility Product during Slow Flux Reversals
Authors: Brownell R. M. , Barker R. C.
Published: March 2008

A previous paper has shown that the sides of slow constant-voltage hysteresis loops on polycrystalline tape-wound cores are not smooth; instead the loop sides show irregular, imperfectly reproducible variations. These variations indicate changes in the ease of motion of the so-called transition region (the outward-moving region, formed of moving domain walls, in which the flux is changing). Such changes imply rearrangements of the domain wallswithin the transition region; and rearrangements of the walls imply changes in their area and mobility. Measurements have been made of a factor K, defined from ec = K(H−Ht), where ec is the induced voltage-per-turn, H is the field applied at the center of the transition region, and Ht is a threshold parameter. K is proportional to the average of the area-mobility product over the walls in the transition region. Using feedback of the induced voltage, Kwas measured by modulating the applied field H in such a way that the resulting modulation in ec was a small-amplitude square wave. The ratio of the modulation amplitudes in ec and H gave K. This technique, which is similar in principle to Becker's, has shown that the area-mobility product varies directly with the average rate of flux change and inversely with the level of prior saturation. In the 50-50 Ni-Fe grain-oriented 2-mil tape core for which results are presented, with a prior saturating field of 10 times the coercive force Hc, as the average induced voltage was varied from 1.2 to 20 μv per turn, the mean value of K increased from 8 to 80 μv-per-turn per ampere-turn-per-meter. With the average induced voltage at 1.2, as the prior saturating field was increased from the vicinity of the coercive force to 2Hc, K dropped from 14 to 9, then remained constant at 8 as HS, the prior saturating field, was increased to 100Hc. It is shown that these results are qualitatively consistent with the results from nonmodulated measurements. It is also shown that the number of active domain walls for K = 15 is of the order of 3, if each wall is assumed to be one wrap-of-tape long and if several other drastic assumptions are made.
Thin-Film Switching in the Hard Direction by Wall Motion
Authors: Spain Robert J. , Rubinstein Harvey
Published: March 2008

Hysteresis loops in thin films observed with the driving field applied perpendicular to the easy axis often exhibit appreciable squareness of the loop, suggesting the existence of another easy axis along what is presumed to be the hard direction. Measurement of the anisotropy in such films indicates a uniaxial anisotropy with the hard axis along the direction in which the second square loop is found. Observing magnetization reversal in these specimens by the Kerr effect, one notices wall motion which is again characteristic of a second easy axis perpendicular to the first. The use of Bitter powder patterns shows this wall activity with sufficient detail to support the theory that the occurrence of an apparent second easy axis can be normal behavior in a film with uniaxial anisotropy. If the characteristics of the film are such as to cause the magnetization to return to a multidomain state when a saturating field is applied along a hard direction and then removed, this direction can be expected to exhibit properties normally associated with an easy axis. The directions which seem to define the hardest axes are then found at angles slightly greater and less than 90°from the real easy axis. The paper describes the theory behind such behavior and the experimental observations which it explains.
Nucleation Processes in Thin Permalloy Films
Authors: Methfessel S. , Middelhoek S. , Thomas H.
Published: March 2008

Normally, wall motion in thin Permalloy films starts from nuclei of reversed magnetization at the edges of the film, which are created by the demagnetizing field. Therefore, for the investigation of nucleation processes inside the film, the edge effects have to be suppressed. This has been done by two methods: The first is based on the use of inhomogeneous driving fields, and the second on the formation of a high coercive force barrier between the edges and the central area of the film. This barrier prevents the edge domains from moving into the central area. Depending on the maximum amplitude of the driving field, different modes of nucleation are possible, leading to different hysteresis loops. Since the domain nucleation must be attributed to a rotational process, the starting field is measured as a function of the uniaxial anisotropy field which is changed by bending the film. The results agree with the dependence found by Preisach for Permalloy wires under stress.
Simple Physical Theory of Spin Wave Interactions
Authors: Keffer F. , Loudon R.
Published: March 2008

A simple and powerful new method for the treatment of spin wave interactions is introduced and used to obtain the corrections to the energy and magnetization of ferromagnets, antiferromagnets and ferrimagnets. The results previously obtained by Dyson and by Oguchi using complicated analysis are reproduced and extended by means of elementary considerations which throw light on the physical interpretation of the corrections. In the case of a ferromagnet the validity of the random phase approximation is discussed, and the properties of the continuous medium model are calculated: in particular, the spin wave exchange-collision cross section is obtained in a simple way.
Improved Magnetic Properties of High-Purity Iron-Cobalt Alloys Containing 27–43% Cobalt
Authors: Shull Daniel S.
Published: March 2008

Interest in iron-cobalt alloys has revived in the last several years because of their high saturation inductions and high Curie temperatures. The development of Supermendur in 1957 demonstrated that outstanding improvements in the magnetic properties of the 49Fe-49Co-2V alloy can be obtained by careful processing and magnetic annealing. This paper describes a survey of the magnetic properties obtained when similar techniques are applied to alloys containing 27–43% cobalt. Significant improvements in both the dc and 400-cps properties were obtained, compared to previous similar compositions of lower purity. The alloys containing 35–43% cobalt with additions of chromium or vanadium had 400 cps core losses approaching those of Supermendur.
Cube Texture in Ultrathin Molybdenum Permalloy Tape
Authors: Koh P. K.
Published: March 2008

With identical annealing heat treatment, the role of the major annealed texture component seems to depend primarily upon the degree of cold reduction. Cube texture was evident when all three thicknesses of tape, 12 mil, 14 mil, and 18 mil, were annealed at 760°C. On raising the annealing temperature to 927°C, there was no trace of cube texture in tape which was cold reduced 96.9% before annealing. But cube texture still remained as the strongest annealing texture component in tapes similarly treated at 927%C but cold reduced only 93.8% and 87.5% respectively, before annealing. The present results agree to some extent, although not entirely,with previous investigators on the transitional nature of cube texture in materials similar to, but not the same as, the present tape.

The switching coefficient Sw increases with increasing cube pole concentration in the order of increasing thickness of tapes annealed at 760° and 927°C. Therefore, 12-mil tape with the highest value of Sw would have the longest switching time in μsec under a constant applied field. The squareness ratio of the hysteresis loop, Br/Bm, at the applied field of 12 oe decreases with the increasing cube pole concentration in the order of increasing thickness of tapes annealed at 760° and 927°C. No correlation could be found between cube pole concentration in annealed tapes and observed coercive force.
High-Temperature Magnetic Lag in Iron-Nickel Alloys
Authors: Gerstner Dieter , Kneller Eckart
Published: March 2008

The kinetics of the lag of permeability (disaccommodation), occurring in quenched iron-nickel alloys with 45–85% nickel at temperatures between 300°C and the Curie temperature, have been investigated. The effect could be analyzed as caused by at least two different diffusion processes: (1) formation of short-range directional order according to Néel and Taniguchi-Yamamoto, and (2) formation of a quasi-isotropic structural change, which is probably formation of Ni3Fe long-range order. In principle, the same lag behavior was found in 5-79-molybdenum Permalloy.
Some Effects of Directional Ordering in Zone-Melted Iron
Authors: Maringer R. E.
Published: March 2008

The effects of C and N in iron were studied with the use of both mechanical and magnetic methods. Internal-friction techniques were used to follow the magnetoelastic aftereffect, and showed the existence of a peak in the magnetoelastic damping near the Snoek peaks. At higher frequencies, the effects of directional ordering were observed with a transformer-type device, the internal-friction specimen acting as the core. Relaxation times calculated from the magnetoelastic data are in good agreement with published data, while relaxation times calculated from the magnetic peaks and from the transformer data are not. Reasons for this apparent discrepancy are discussed.
Losses in Silicon Iron at Very Low Frequencies and High Flux Densities
Authors: Wycklendt Daniel A. , Kay Robert M.
Published: March 2008

Past measurements of losses in soft magnetic materials magnetized to high flux densities have been largely confined to determination of a quasi-static hysteresis loss over a nondescript cycle of magnetization and losses with sinusoidal magnetization with frequencies greater than 15 cps. However, since the simple concept of a hysteresis loss combined with an eddy current loss in a homogeneous medium has become outmoded, measurements of losses resulting from sinusiodal magnetization over a frequency spectrum from near zero to power frequencies are desirable. This paper describes losses in (110) [001] textured silicon iron strips which were magnetized with sinusoidal induction of negligible distortion in the frequency range 0.02–100 cps. Flux density amplitudes of 10, 15, and 17 kilogauss were used. A direct-coupled amplifier with very large negative feedback and a low distortion oscillator were used to excite the specimens. Losses in the range 0.02–0.4 cps were obtained from loop measurements;bridge measurements were made in the range 0.4–100 cps. The measurements reveal a sharp drop in the loss per cycle as the frequency is decreased from 1.5 to 0.02 cps. The downward concavity of the loss-frequency curve which has been observed previously for the power frequency range is therefore, even more prominent at very low frequencies. The effect increases with the amplitude of the flux density.
Equilibrium Atmosphere Schedules for the Cooling of Ferrites
Authors: Blank John M.
Published: March 2008

Phase diagrams including contour lines of constant ferrous ion content in oxygen-partial-pressure vs temperature coordinates were determined for two MnZn ferrites and two NiZn ferrites containing excess iron. A “universal” equilibrium atmosphere diagram which is applicable to a wide variety of ferrites was synthesized from these data. This diagram specifies the schedules of temperature and percent oxygen by which ferrites can be cooled from the sintering temperature without net gain or loss of oxygen.
Remanent Magnetization of a Synthetic Hematite Single Crystal
Authors: Lin S. T.
Published: March 2008

The remanence of a virgin sample of a synthetic single crystal of hematite has been carefully measured along different directions through a temperature range between 77° and 420°K. The effect of a directive field as applied through the low temperature transition on the remanence also has been studied. Some remarkable phenomena in contrast with those of the natural crystal have been recognized. (1) There is no weak ferromagnetism along the [111] direction. (2) The weak ferromagnetism is strictly limited to the (111) plane above the Morin transition and sharply reduced to zero below 259°K. The thermal hysteresis of the remanence-temperature curve forms a perfect square loop. (3) If the sample were warmed through transition in zero external magnetic field no ferromagnetism could be observed along any direction in the crystal. This leads to the conclusion that the antiferromagnetic axes form equilateral triangular arrangment in the basal plane (111) above transition. The experimental data support the phenomenological theory of weak ferromagnetism of Dzyaloshinsky and Vonsovsky.
Preparation and Properties of Thin Ferrite Films
Authors: Banks E. , Riederman N. H. , Schleuning H. W. , Silber L. M.
Published: March 2008

Thin films of ferrites, of the order of 1000 A thickness, have been prepared by vacuum evaporation of the metals, and subsequent high-temperature oxidation. Films of iron, nickel, cobalt, magnesium, and copper ferrites, mixed ferrites, and mixed ferrite-aluminates, as well as yttrium iron garnet, have been prepared. X-ray powder diffractometry indicates that the ferrite films are single-phase spinels, while the garnet shows the garnet structure. In many respects, the properties of the films are the same as those of bulk ferrites of similar composition. The resistivity of the films can be controlled by proper oxidizing procedures. X-band magnetic resonance measurements indicate that the saturation magnetizations of the films are comparable to those of the corresponding bulk ferrites, though the films show larger resonance linewidths. It has been possible to prepare magnesium ferrite films with magnetizations from 2200 gauss to less than 500 gauss by proper annealing and quenching. The possible advantages of thin films are that they allow optical studies of the material by transmission, and should permit determination of magnetic exchange constants through observation of spin wave resonances.
Ferrite Thin Films
Authors: Lemaire Henry P. , Croft William J.
Published: March 2008

Thin films of ferrites of various compositions have been prepared. Two methods have been developed, both involving a spray technique whereby hot suspensions of hydroxides are directed onto a heated substrate. The ferrite films are formed essentially through a coprecipitation mechanism. X-ray diffraction has shown that the films have a cubic spinel structure. Various compositions have been attained; magnetite, nickel ferrous ferrite, a magnetite-zinc ferrite series, and other mixed ferrites. Coercive force measurements were made from hysteresis loops obtained on a 1000-cycle loop tracer. The films are magnetically isotropic and have a high squareness ratio. Film thicknesses have been varied from a few hundred A to about 1 μ. Relative film thicknesses were estimated by using a spectrophotometric technique. For a fixed composition, coercive force decreases with increasing thickness. Magnetite films had coercive forces varying from 170 to 300 oe depending on thickness. A nickel ferrous ferrite series had coercive forces varying from 225 oe for thick films to 400 oe for a very thin one. Coercive force measurements are related to composition variations in a series of zinc ferrous ferrite films.
Triangular Moment Arrangements in Manganese-Iron Spinels
Authors: Moruzzi Victor L.
Published: March 2008

The anomalously low magnetic moments for MnxFe3−xO4 spinels with 1<x≤3 are qualitatively explained by a Yafet-Kittel triangular moment arrangement. Values of β, n, and α are calculated from measurements of magnetic moment, high field susceptibility, and Curie temperature. The measurements on Mn3O4 yield a moment of 1.73 Bohr magnetons and a susceptibility of 3.5×10−4 gauss/oersted. An extrapolated anisotropy field of 150 kilo-oersted is found. Transitions from the triangular state to a Néel-type arrangement are found to occur for x = 1.25, x = 1.55, and x = 1.80. For Mn3O4, αβ values suggest that the vanishing of the spontaneous magnetization at 42°K represents a transition to a paramagnetic-antiferromagnetic state.
Annealing of Oblique-Incidence Permalloy Films
Authors: Weiss G. P. , Smith D. O.
Published: March 2008

The anisotropy of evaporated Permalloy films (composition near zero magnetostriction) deposited on glass at 45° to the substrate normal and at a substrate temperature of 200°C has been studied after anneal for several hours at 300°C. After anneal the room temperature easy axis of films with positive magnetostrictionis in the original direction. However, films with negative magnetostriction develop a new room temperature easy axis 90° to the original one; at 300°C the easy axis is in the original direction. Application of a large magnetic field in any direction during anneal does not influence the final magnetic anisotropy in either case. These effects are qualitatively explained by assuming the anneal to increase the tension along the long axis of oblique-incidence chains, a process which converts surface energy into strain energy. Anisotropy was measured by resonance in a coaxial bridge over the frequency range 50 Mc to 2100 Mc. A rectangular coaxial cavity is used which can be heated to 500°C in a vacuum of 10−6 mm Hg; continuous angular orientation of the film is possible with a resolution of ±0.5°. Bridge balance is good enough to permit samples of less than 100 A thickness to be measured.
Annealing Behavior and Temperature Dependence of the Magnetic Properties of Thin Permalloy Films
Authors: Segmüller Armin
Published: March 2008

Permalloy films are evaporated in a vacuum of 10−5 mm Hg in the presence of a magnetic field to achieve a uniaxial anisotropy. All annealing treatments and magnetic measurements are performed simultaneously in a vacuum of 10−8 to 10−7 mm Hg. In a film never heated above the deposition temperature, the temperature dependence of the uniaxial anisotropy is stronger than in bulk Permalloy, and magnetic annealing changes the anisotropy even at temperatures below 350°C. These changes are strongly dependent on whether or not the magnetization is aligned in the hard direction during cooling. During annealing above 400°C the coercive force is increased, and subsequent magnetic annealing treatments exhibit kinetics similar to those of bulk material.
Magnetic Ordering in the Ferromagnetic Rare-Earth Metals
Authors: Yosida Kei , Miwa Hirosi
Published: March 2008

The ferromagnetic rare-earth metals show the magnetic transition from the ferromagnetic state to the antiferromagnetic state. The possibility of this kind of magnetic transition between spin arrangements is discussed on the basis of the spin wave approximation. It is shown that the transition from the ferromagneticto the helical spin arrangement which has recently been observed in dysprosium and holmium can occur when a large axial anisotropy field exists. The temperature dependence and the field dependence of the pitch of the helical structure are calculated on the same standpoint of the spin wave theory.