Anomalous Point Research Articles

Anomalous Point Defect Injection During Pulsed Laser Melting Processes: Direct Evidence of Gai and Asi Profiles in GaAs

AbstractSignificant point defect injection during a pulsed laser melt process is reported for the first time. Heteroepitaxial InxGa1-xAs/GaAs layers fabricated by a pulsed laser induced epitaxy technique are used in this study. Transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) and secondary ion mass spectrometry (SIMS) are employed to study the redistribution behavior of each species on the atomic scale. It is found that both the Si dopant species and the Ga, As, and In host atoms are injected into the underlying GaAs substrate. These species are then significantly redistributed, forming near spherical As-rich regions. Direct evidence of Asi and Gai (Ga and As interstitialcies) profiles in the GaAs substrate are also obtained for the first time. A hypothesis, based upon the combined effects of concentration impulse and large temperature gradients across the liquid-solid interface, is proposed to explain the significant solid phase diffusion observed during the pulsed laser melting process. We estimate the temperature gradient induced electric field during the process to be on the order of 104V/cm.

Västanå-Järkvissle Sn-Li occurrence found by regional grid sampling of heavy-mineral till concentrates in northern central Sweden

Regional exploration for pegmatite hosted Sn-mineralization in Sweden by LKAB Prospektering has, since the early 1980s, generally been based on the use of heavy-mineral concentrates from till collected by roadside sampling. The average sampling density has been 0.5–1.0 sample/km 2, but with an uneven distribution of sample points within areas investigated. Planning of the regional sampling grid in this study has been based on a statistical analysis to answer the following question: What sample density and grid-spacing should be used to hit an anomalous target with the highest possible probability. The statistical analysis indicates that using a rectangular grid, 750 × 1,500 m (0.88 sample/km 2), the probability of intersecting an anomalous target is 100%. Heavy-mineral till concentrate sampling using this grid design in northern central Sweden in 1981 revealed one single, extremely high sample with 4,622 ppm Sn indicating mineralization in the area north of the village of Järkvissle. In 1982–1983, while boulder tracing up-ice from the anomalous regional sample point, cassiterite and spodumene-bearing boulders and outcrops were found. Two parallel mineralized pegmatites within an area of approximately 5,000 m 2 with grades of 0.04–0.07% Sn and 0.40–0.92% Li 2O have recently been located NW of Järkvissle. Semi-regional (250 × 500 m) and local (20 × 20–160 m) sampling of till gave some anomalous values of Sn and Li in concentrates, which to some extent could be correlated with mineralized boulders and outcrops, and also indicated new targets for drilling. The results from a simplified sample preparation technique for heavy-mineratl till concentrates show that a new device, named the Goldhound, can be used in future geochemical prospecting for Sn and Li in Sweden.

Disparity-induced vergence responses in normal and strabismic subjects.

Latencies of vergence responses were obtained by presenting vertical line stimuli for 0.5 sec to the fovea of one eye and to various retinal locations of the other eye of four subjects with normal binocular vision, one exotrope with normal retinal correspondence, and four esotropes with anomalous correspondence. Vergence latencies were larger for squinters than nonsquinters and were especially long for the squinters with anomalous correspondence. For three of the four anomalous corresponders, the direction of the vergence movement (convergence or divergence) was based on the location of the stimulus with respect to the anomalous retinal point in the deviating eye--not with respect to the fovea as occurred for the subjects with normal correspondence.

Strain rate behaviour of Saint-Jean-Vianney clay: Discussion

The paper by Vaid, Robertson, and Campanella is notable because (a) the Saint-Jean-Vianney (SJV) clay is considered to be particularly susceptible to effects; (b) the measurements were made with special care; and (c) the results can be used to examine some central questions concerning in situ behaviour of sensitive clay soils. Crawford (1964) performed oedometer tests on samples of sensitive Leda clay in which the dmation of each load increment was varied from about 1 h to 1 week. He concluded that compressibility was strain-rate dependent and that the quasi-preconsolidation pressure (Leonards and Ramiah 1959) was strongly dependent on the loading procedure. Bjerrum (1967, 1972~) developed hypotheses to explain these phenomena and proposed (Bjerrum 1972b) that the quasi-p,' would actually vanish at field rates of strain. Although these views have been vigorously opposed (Leonards 1968, 1972, 1977), the prevailing opinion is to accept their validity. From the authors' Fig. 2, the change in void ratio per unit change in effective stress was calculated for stress increments of 900-1000, 1500-1 600, and 20003000 kPa, at different rates of load application. The results are shown plotted in Fig. 1. It is seen that at stress levels above the quasi-p,' compressibility is time independent (actually decreases somewhat with increased load duration), whereas for the stress level that straddles the quasi-p,' compressibility increases markedly with increasing load duration. Now, it has long been recognized that exceeding the quasi-p,' causes a breakdown in soil structure, which is accompanied by a marked increase in time-dependent secondary compression^.^ A manifestation of this phenomenon is an anomalous point on the otherwise continuous plot of secondary compression/consolidation settlement versus load increment ratio (Leonards and Girault 1961). Figure 1 of the authors' paper shows that at stress levels below about 800 kPa the effect of time on compressibility (indeed, the compressibility itself) is very small. Tests on artificially sedimented clays (Leonards and Altschaeffl 1964; Leonards 1972)

Strain rate behaviour of Saint-Jean-Vianney clay: Discussion

The paper by Vaid, Robertson, and Campanella is notable because (a) the Saint-Jean-Vianney (SJV) clay is considered to be particularly susceptible to "strain-rate" effects; (b) the measurements were made with special care; and (c) the results can be used to examine some central questions concerning in situ behaviour of sensitive clay soils. Crawford (1964) performed oedometer tests on samples of sensitive "Leda" clay in which the dmation of each load increment was varied from about 1 h to 1 week. He concluded that compressibility was strain-rate dependent and that the quasi-preconsolidation pressure (Leonards and Ramiah 1959) was strongly dependent on the loading procedure. Bjerrum (1967, 1972~) developed hypotheses to explain these phenomena and proposed (Bjerrum 1972b) that the quasi-p,' would actually vanish at field rates of strain. Although these views have been vigorously opposed (Leonards 1968, 1972, 1977), the prevailing opinion is to accept their validity. From the authors' Fig. 2, the change in void ratio per unit change in effective stress was calculated for stress increments of 900-1000, 1500-1 600, and 20003000 kPa, at different rates of load application. The results are shown plotted in Fig. 1. It is seen that at stress levels above the quasi-p,' compressibility is time independent (actually decreases somewhat with increased load duration), whereas for the stress level that straddles the quasi-p,' compressibility increases markedly with increasing load duration. Now, it has long been recognized that exceeding the quasi-p,' causes a breakdown in soil structure, which is accompanied by a marked increase in time-dependent secondary compression^.^ A manifestation of this phenomenon is an anomalous point on the otherwise continuous plot of secondary compression/consolidation settlement versus load increment ratio (Leonards and Girault 1961). Figure 1 of the authors' paper shows that at stress levels below about 800 kPa the effect of time on compressibility (indeed, the compressibility itself) is very small. Tests on artificially sedimented clays (Leonards and Altschaeffl 1964; Leonards 1972)

The calculation of perturbation and induction arrows for a three-dimensional conductivity model.

A numerical method is used to calculate the electromagnetic fields associated with a three-dimensional conductivity anomaly. A uniform field oriented in various directions relative to the anomaly is used as the source. The transfer functions and related perturbation and induction arrows associated with the fields are calculated. The results show that the perturbation arrows do not well describe the anomalous currents for the three-dimensional model considered, but can give a method of outlining the spatial extent of the anomaly. The induction arrows may be used in the traditional way to indicate the flow of anomalous currents and point toward conductivity inhomogeneities. Two methods of calculating the induction arrows are compared.

The Effects of the Crystal-structural Transformation on the Chemical Behavior of 64Cu Recoil Atoms in α-Copper Phthalocyanine

Abstract The Stage-II annealing process of 64Cu recoil atoms in neutron-irradiated α-copper phthalocyanine was carefully examined. The isothermal annealing curve above 270°C showed anomalous inflection point. It was found that the Stage-II annealing process of the α-crystal consisted of a “normal” monotonous annealing process and a “delayed” process caused by the crystal-structural transformation. The results of a kinematic analysis suggested that the fluctuation of the matrix and the change in the crystalographic factors due to the structural transformation play a triggering role in the delayed annealing reaction.

Pion-deuteron dispersion relations in impulse approximation

Dispersion relations for pion-deuteron forward scattering π+D → π+D are discussed by using the impulse approximation for the calculation of the contribution in the unphysical region which is due to the absorptive process π+D→N+N. Special regard is taken to the anomalous situation which is investigated by explicit analytic continuation of the contribution from the absorptive process in the dispersion relations with respect to the pion mass. It is found that an anomalous logarithmic branch point and an anomalous pole appear at the same point, which coincides with that found in perturbation theory where the deuteron is treated as elementary. It turns out that the anomalous situation is only governed by the asymptotic behaviour of the occuring deuteron wave functions. It is further shown that the spin-flip dispersion relation can be used for a determination of the pion-nucleon coupling constant. The value found by employing the impulse approximation for the spin-flip amplitude in the observable region of the dispersion relation agrees within 10% with that following from the corresponding pion-nucleon dispersion relation. For this agreement the consideration of the anomalous pole contribution is necessary.

Relation between the Anomalous Freezing Point Depression and the Mechanical-Elastic Behavior of Gels

Relation between the Anomalous Freezing Point Depression and the Mechanical-Elastic Behavior of Gels

On the Anomalous Melting Point and the Decomposition of Acetyl-salicylic Acid

On the Anomalous Melting Point and the Decomposition of Acetyl-salicylic Acid

The Language and Origin of the Basques

THE Basques or Euskaldunak (i.e. “the Men”), as they call themselves, are a most remarkable people who have long been an interesting problem to ethnologists. The most anomalous point about the Basques is their language, which is as typically agglutinative as any Asiatic or American tongue. Ripley, in his fine book “The Races of Europe,” points out that the verb habitually includes all pronouns, adverbs and other allied parts of speech; as an example of the appalling complexity possible as a result, Bladé gives fifty forms in the third person singular of the present indicative of the regular verb “to give” alone. Another often quoted example of the effect of such agglutination occurs in a reputed Basque word meaning “the lower field of the high hill of Azpicuelta,” which runs,