bluuebunny/crossref_metadata_2025 huggingface dataset:
Steam output from fumaroles of an active volcano: Tectonic and magmatic‐hydrothermal controls on the degassing system at Vulcano (Aeolian arc)
Authors: Italiano F. , Pecoraino G. , Nuccio P. M.
Published: February 2004

The results from measurements of extensive parameters (steam output and exhaling surface area) taken at the crater fumarolic field of Vulcano Island (Aeolian arc, southern Italy) are reported along with a detailed description of the measuring method. The steam emission rate increased by 1 order of magnitude during the observation time (1983–1995), while its concentration in the released gases was only slightly changed. During the same period the total exhaling surface expanded from 50 m2 to more than 2400 m2 and evolved following preferential trends that coincide with the main tectonic structures of the island. The observed peaks in steam output show a positive correlation with episodes of volcanic activity unrest. The temporal increase of steam output and the observed development in the exhaling surface areas are consistent with a volcano‐tectonic triggering of the exhaling activity. Particularly, the peaks in the steam output are interpreted as a consequence of degassing from an active magma, slowly moving toward the surface.
Accelerated denudation and tectonic/geomorphic reactivation of the cratons of northeastern Brazil during the Late Cretaceous
Authors: Harman Rebecca , Gallagher Kerry , Brown Roderick , Raza Asaf , Bizzi Luiz
Published: February 2004

Apatite fission track (AFT) data for a suite of 40 outcrop samples from the São Francisco and eastern Guaporé cratons in northeastern Brazil record between 60° and 100°C of cooling since the separation of South America and Africa at ∼130 Ma. Quantitative thermal histories derived from the data indicate two discrete phases of cooling: the first is coeval with continental breakup at ∼130 Ma and the second is broadly coincident with the change in relative plate motion at ∼60–80 Ma. The thermal histories indicate an increase in the average rate of denudation at ∼60–80 Ma over much of the interior of northeastern Brazil. Estimated total amounts of postbreakup denudation vary between 3 and 7 km, with greater amounts occurring along the eastern and northern margins of the São Francisco and Guaporé cratons, respectively. Two samples within the Pernambuco shear zone yield anomalously young AFT ages which record cooling caused by locally enhanced denudation rates during the Late Cretaceous. The timing and style of the Late Cretaceous tectonic event in Brazil is similar to the analogous Late Cretaceous history of the central African shear zone system in Africa. This suggests that both events were associated with intracontinental deformation caused by major changes in the relative plate motions between Africa, Antarctica, and South America that began between anomaly C34 (83 Ma) and C31 (67 Ma).
The evolution of the deep flow regime at Soultz‐sous‐Forêts, Rhine Graben, eastern France: Evidence from a composite quartz vein
Authors: Smith M. P. , Savary V. , Yardley B. W. D. , Valley J. W. , Royer J. J. , Dubois M.
Published: February 2004

Drilling at Soultz‐sous‐Forêts, France, conducted as part of the European Hot Dry Rock Project, intersected a fracture lined with vein quartz and actively producing hot (150°C) water at 2174 m depth in the granite basement to the Rhine Graben. At least seven generations of quartz are present within the vein, but fluid inclusion homogenization temperatures show that temperatures remained within 15°C of the present field temperature throughout its development, apart from a few rare pulses of hotter water. In contrast, freezing measurements indicate two distinct fluids. The more saline one, ranging from 10 to 15 wt % NaCl eq, dominated the early stages of vein fill, while the second, ranging from 0 to 8 wt % NaCl eq, become more prominent in later stages. Oxygen isotope analyses of different quartz generations also show two populations in addition to magmatic relicts. In the early stages a population with δ18O from 14‰ to 18‰ predominates and is consistent with growth from a sedimentary basin brine. Later quartz shows lighter values (12‰–13‰), resulting from precipitation from a fluid isotopically identical to the modern fluid, which is in equilibrium with granite feldspar at a temperature ∼25°C higher than the present vein temperature. The change in δ18O does not, however, correlate with that in fluid salinity, reflecting the different effects of fluid‐rock interaction on the two parameters. Changes in fluid salinity, possibly resulting from meteoric inputs into the deep formation waters of the Rhine Graben, occurred early in the flow path of the Soultz fluids because there is no decrease in fluid temperature associated with even the most dilute inclusion fluids. With time the path by which these fluids from deep in the Mesozoic sediments of the graben have made their way to the Soultz site has changed, resulting in greater interaction with granite, as recorded in the oxygen signature.
Bias in the centroid moment tensor for central Asian earthquakes: Evidence from regional surface wave data
Authors: Patton Howard J.
Published: February 2004

Surface waves recorded on the Chinese Digital Seismic Network (CDSN) station Urumqi (WMQ) are analyzed for 26 centroid moment tensor (CMT) earthquakes located within an epicentral distance of 1300 km. Applying a simple grid search method for source parameter retrieval, I obtain revised estimates of the focal depth, fault strike, and seismic moment (M0) from amplitude spectra of Love and Rayleigh waves and compare these estimates with the CMT best double‐couple solutions. The comparisons show that residuals are unbiased for focal depth and fault strike, where population spreads are ±13 km and ±17°, respectively. On the other hand, M0 estimates are found to be biased, with CMT M0 larger than regional estimates by an average of 0.27±0.04 log units. The results for focal depth and strike are consistent with previous global and regional studies comparing independent estimates with CMT results. Recent full‐waveform modeling studies for central Asian earthquakes support the findings of bias in M0 estimates. I suggest that causes for M0 bias may be related to great thicknesses of continental crust in Hindu Kush and Tien Shan regions and to data censoring practices at small magnitudes. M0:mb scaling relationships for central Asian earthquakes show better agreement with western U.S. scaling when M0 estimates determined in this study are used.
Seismotectonic analysis of the Tjörnes Fracture Zone, an active transform fault in north Iceland
Authors: Rögnvaldsson Sigurður T. , Gudmundsson Agust , Slunga Ragnar
Published: February 2004

The Tjörnes Fracture Zone is a transform fault connecting the rift zone of the Kolbeinsey Ridge with that of north Iceland. The main transform motion takes place on the Húsavík‐Flatey Fault, a major 7–9 Myr old right‐lateral fault. In addition to this fault, there are two major seismic lineaments associated with the Tjörnes Fracture Zone; the Grímsey lineament and the Dalvík lineament. These lineaments are marked by concentrations of seismicity with the largest earthquakes reaching magnitude 7. The maximum depth of earthquakes is 10–12 km and increases with distance from the spreading axis. We determined accurate relative locations and focal mechanisms of more than 800 earthquakes in 62 clusters on the principal seismic lineaments. The estimated relative location uncertainty for most of the relocated earthquakes is 2–20 m. The best fitting plane through each cluster is assumed to coincide with the fault plane of the group of earthquakes. For clusters near the Húsavík‐Flatey Fault the fault planes are right‐lateral and strike N122°E–N140°E, similar to the overall strike of the Húsavík‐Flatey Fault. This agrees with the right‐lateral displacement on the fault as well as with field observations of numerous transform‐parallel right‐lateral faults associated with the main fault. By contrast, earthquake clusters on the lineaments of Grímsey and Dalvík define (mostly) left‐lateral planes striking roughly north‐south, i.e., at 40°–90° to the overall trend of these lineaments. Field observations show that left‐lateral, north‐south trending fault planes are also common in the on‐land parts of the Dalvík lineament. The different style of faulting probably represents transform faults at different stages of development.
Global postseismic gravity changes of a viscoelastic Earth
Authors: Soldati G. , Piersanti A. , Boschi E.
Published: February 2004

A spherically symmetric Earth model with a viscoelastic mantle and an inviscid core is used to study the gravitational perturbation due to a lithospheric shear dislocation in the coseismic and postseismic regime. Our approach is based on a quasi‐static solution of the equilibrium equations taking advantage of the normal mode technique for a layered incompressible Earth with linear viscoelastic rheology. We perform a systematic study of space and time evolution of gravity changes associated with a wide selection of seismic sources investigating the effects of several different mantle viscosity profiles. Our results show that the gravitational signal is sensitive not only to the viscosity of the asthenosphere but also to that of the mantle, including the portion below the 670 km discontinuity. As a case study, we compute the coseismic and postseismic gravity perturbation due to the 1964 Alaska earthquake. The last section is devoted to the analysis of the postseismic relaxation rates of the gravitational perturbation following that earthquake for several different viscosity profiles of the mantle. Our results show that experimental attempts to obtain reliable detection of static and quasi‐static gravitational perturbation associated with seismic events would be of great importance in understanding the dynamic and viscosity profile of both upper and lower mantle.
Integrated satellite interferometry: Tropospheric noise, GPS estimates and implications for interferometric synthetic aperture radar products
Authors: Williams Simon , Bock Yehuda , Fang Peng
Published: February 2004

Interferometric synthetic aperture radar (INSAR), like other astronomic and space geodetic techniques, is limited by the spatially and temporally variable delay of electromagnetic waves propagating through the neutral atmosphere. Statistical analysis of these variations, from a wide variety of instruments, reveals a power law dependence on frequency that is characteristic of elementary (Kolmogorov) turbulence. A statistical model for a major component of the delay fluctuations, the “wet” component, has previously been developed byTreuhaft and Lanyi[1987] for very long baseline interferometry. A continuous Global Positioning System (GPS) network is now in place in southern California that allows estimation of, along with geodetic parameters, the total delay due to the atmosphere above each site on a subhourly basis. These measurements are shown to conform to the Treuhaft and Lanyi (TL) statistical model both temporally and spatially. The TL statistical model is applied to the problem of INSAR and used to produce the covariance between two points separated in time and/or space. The error, due to the atmospheric variations, for SAR products such as topography and surface deformation is calculated via propagation of errors. There are two methods commonly cited to reduce the effect of atmospheric distortion in products from SAR interferometry, stacking and calibration. Stacking involves averaging independent interferograms to reduce the noise. Calibration involves removing part (or all) of the delay using data from an independent source such as total zenith delay estimates from continuous GPS networks. Despite the relatively poor spatial density of surface measurements, calibration can be used to reduce noise if the measurements are sufficiently accurate. Reduction in tropospheric noise increases with increasing number of measurement points and increasing accuracy up to a maximum of √N, whereNis the number of points. Stacking and calibration are shown to be complementary and can be used simultaneously to reduce the noise to below that achievable by either method alone.
Model for nonlinear wave propagation derived from rock hysteresis measurements
Authors: Xu Heming , Day Steven M. , Minster Jean‐Bernard H.
Published: February 2004

We develop a method for modeling nonlinear wave propagation in rock at intermediate strain levels, that is, strain levels great enough that nonlinearity cannot be neglected but low enough that the rock does not incur macroscopic damage. The constitutive model is formulated using a singular‐kernel endochronic formalism which satisfies a number of observational constraints, including producing a power law dependence of attenuation (Q−1) on strain amplitude. One free parameter represents cubic anharmonicity, and we set it to agree with laboratory observations of harmonic distortion. Another free parameter controls the amount of hysteresis; it is set to approximate laboratory stress‐strain curves. The resulting phenomenological model provides a convenient means to parameterize laboratory observations in a form suitable for efficient wave propagation calculations. We solve one‐dimensional wave propagation problems for this constitutive model using both finite difference and pseudospectral methods. Quasi‐harmonic wave propagation in the Berea sandstone model shows several departures from results obtained with nonlinear elasticity: (1) more rapid decay with distance of the fundamental frequency component due to nonlinear, amplitude‐dependent attenuation; (2) enhanced excitation of the third‐order harmonic, in agreement with laboratory observations, and saturation, with propagation distance, of the harmonics. This behavior reflects competing effects of harmonic amplitude growth via nonlinear energy transfer from the source frequency and amplitude‐dependent energy dissipation due to hysteresis. We also find that a two‐frequency source function generates harmonics with frequencies which can be expressed as linear combinations of integer multiples of the source frequencies, in agreement with published laboratory results.
Interpretation of aeromagnetic anomalies in terms of hydrothermal alteration in Cretaceous normal polarity superchron extrusives of the Troodos, Cyprus, ophiolite
Authors: Walls Charles C. , Hall James M.
Published: February 2004

One hundred and twenty–two meters altitude aeromagnetics and ground data over the Cretaceous normal polarity extrusives of the Troodos ophiolite have allowed source modeling. These data have been digitized and recontoured in gridded and reduced to the pole (RTP) formats. The principal result is confirmation of large anomalies with amplitudes of several thousand nanoteslas and dimensions of 1–6 km. Since the extrusives are everywhere normally magnetized, anomalies must have an explanation other than polarity reversals. Strong magnetization of overlying little altered extrusives and dikes, and weak magnetization of underlying hydrothermalty altered material, allows forward modeling in terms of source layer thickness. Detailed modeling was carried out for ∼50 km2 subarea containing two highs separated, with 3000 nT contrast, by a low, for which ground information had been specifically acquired. The low coincides with a thick series of sheet flows containing former hydrothermal flow‐ways (gossans). Modeling of a former reservoir of hydrothermal fluid beneath the low, with reduction of the magnetic source layer from 1000 to 250 m, is consistent with observations. For the extrusives as a whole, gossans are weakly associated with relatively low RTP field. Although individual gossans are too small to perturb the kilometer‐scale anomalies, they do show several relationships with anomalies: Gossans are absent from areas of very high (>6500 nT) and very low (<1500 nT) RTP field and, within the intervening range, they are bimodally distributed. Reconsideration of the nature of gossans accounts for some of these features.
Optical and microphysical parameters of the Mt. Pinatubo aerosol as determined from MIPAS‐B mid‐IR limb emission spectra
Authors: Echle G. , von Clarmann T. , Oelhaf H.
Published: February 2004

High‐resolution mid‐IR limb emission spectra were recorded during a flight of the Michelson interferometer for passive atmospheric sounding, balloon‐borne version (MIPAS‐B) from Kiruna, northern Sweden (68°N) on March 14/15, 1992. These spectra are affected by the Mt. Pinatubo stratospheric aerosol, which caused an enhanced continuum emission, especially in spectra of low tangent altitudes. Aerosol extinction coefficients were retrieved from MIPAS‐B spectra at approximately 60 spectral positions in the 750–980 cm−1 and 1180–1380 cm−1 spectral ranges. Retrieved aerosol extinction coefficients range from 6×10−4 km−1 to 3×10−3 km−1 in tangent altitudes 11.3 km and 14.5 km and from 5×10−5 km−1 to 1×10−3 km−1 in 16.1 km. Their distinct spectral shape indicates the presence of H2SO4‐H2O droplets. Compositions and size distribution parameters were retrieved by least squares fitting of Mie‐generated spectral extinction coefficients to the ones derived from the spectra. Estimated spectral single‐scattering albedos between 0.08 and 0.3 indicate the significance of thermal multiple scattering. Multiple‐scattering corrections led to an increase of spectral extinction coefficients by 5–50% with highest changes at lowest tangent altitudes. Accordingly, estimated volume densities have increased by 4–20% to values of 3.66, 2.85, and 0.93 μm3 cm−3 for tangent altitudes 11.3, 14.5, and 16.1 km, respectively. Retrieved H2SO4 weights of 66–70% are in good agreement with values derived from stratospheric temperatures and water vapor partial pressures. Estimated surface densities are systematically low in comparison with in situ size distribution measurements. This finding is explained by the underestimation of small particles by the use of a monomodal size distribution in the analysis. Retrieved effective radii of up to 0.8 μm were found to be consistent with the temporal evolution of the Mt. Pinatubo aerosol.
CV8, a new combination of dihydroartemisinin, piperaquine, trimethoprim and primaquine, compared with atovaquone–proguanil against falciparum malaria in Vietnam
Authors: Giao Phan T. , de Vries Peter J. , Hung Le Q. , Binh Tran Q. , Nam Nguyen V. , Kager Piet A.
Published: February 2004

Objectives  To study a new combination, based on dihydroartemisinin and piperaquine (CV8) and atovaquone/proguanil (Malarone) for treatment of uncomplicated falciparum malaria in Vietnam.

Methods  Vietnamese adults with falciparum malaria were allocated randomly to treatment with dihydroartemisinin/piperaquine/trimethoprim/primaquine 256/2560/720/40 mg (CV8, n = 84) or Malarone 3000/1200 mg (n = 81), both over 3 days. Patients were followed‐up for 28 days.

Results  All patients recovered rapidly. The mean (95% CI) parasite elimination half‐life of CV8 was 6.8 h (6.2–7.4) and of Malarone 6.5 h (6.1–6.9) (P = 0.4). Complete parasite clearance time was 35 (31–39) and 34 h (31–38) (P = 0.9). The 28‐day cure rate was 94% and 95%, respectively (odds ratio 0.84, 95% CI 0.18–3.81). No significant side‐effects were found.

Conclusion  CV8 and Malarone are effective combinations against multi‐drug resistant falciparum malaria. CV8 has the advantage of a low price.
Strengthening health services to control epidemics: empirical evidence from Guinea on its cost‐effectiveness
Authors: Van Damme Wim , Van Lerberghe Wim
Published: February 2004

Objective  To assess the cost‐effectiveness of control measures implemented against epidemics in Guinea, West Africa.

Methods  We collected all routine data available on incidence, mortality, control measures implemented and their cost during epidemics of cholera, measles and meningococcal meningitis in 1993–95. Then we estimated for one prefecture the effectiveness and cost‐effectiveness of epidemic control measures for three scenarios: (i) ‘natural’ situation, (ii) ‘routine’ health services and (iii) ‘intervention’. Where uncertainty was considerable, we used sensitivity analysis and estimated ranges.

Findings  Routine health services reduced potential deaths by 51% (67%, 37% and 60% for cholera, measles and meningitis, respectively), and additional interventions further decreased potential deaths by 28% (28%, 27% and 30% for cholera, measles and meningitis, respectively). The marginal cost‐effectiveness of epidemic control measures in routine health services was US$29 per death averted. The marginal cost‐effectiveness of additional interventions was US$93 per death averted.

Conclusion  Even with the data weaknesses that characterize situations of epidemics it is possible to show that strengthening health services to control epidemics as was performed in Guinea was highly cost‐effective. Moreover, sensitivity analysis over a range of assumptions confirms that (i) well‐functioning health services averted the major part of avoidable deaths, (ii) combining existing health services with additional interventions minimizes the health impact of epidemics and (iii) case management should be a cornerstone of control of epidemics of cholera, measles and meningococcal meningitis.
IgE antibody to Aspergillus fumigatus recombinant allergens in cystic fibrosis patients with allergic bronchopulmonary aspergillosis
Authors: Knutsen A. P. , Hutcheson P. S. , Slavin R. G. , Kurup V. P.
Published: February 2004

Background:  Allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis (CF) is characterized by a heightened Th2 CD4+ T‐cell response to Aspergillus fumigatus (Af) allergens and a hyper‐immunoglobulin E (IgE) state compared with cystic fibrosis patients without ABPA. The IgE serologic differentiation of ABPA from atopic CF patients can be difficult. We propose as the reactivity with purified antigens varies qualitatively and quantitatively and that the antibody response is more specific than with crude Af antigen extract, the IgE responses to purified recombinant Af allergens may differentiate ABPA from atopic CF patients.

Methods:  Serum IgE reactivity to seven recombinant purified allergens and to a crude extract of Af was measured in 15 ABPA, in 23 Af skin test positive (ST+), and in 19 Af skin test negative (ST−) CF patients. Four of the ABPA CF patients were studied before and after developing ABPA. Nine ABPA patients were studied during flares and remissions of ABPA.

Results:  Allergic bronchopulmonary aspergillosis patients had significantly increased IgE reactivity to Asp f2, f3, f4, f6, and f16 compared with the Af ST+ and ST− non‐ABPA CF patients. In the ABPA patients studied before and after developing ABPA, IgE reactivity also increased to Asp f2, f3, f4, and f6, and to the crude extract. In ABPA CF patients, IgE reactivity to Asp f1, f2, f3, and f6 significantly increased during periods of ABPA flares compared with periods of remission. Analysis of the receiver operating curve demonstrated that IgE reactivity to Asp f3 and f4 gave the best sensitivity and specificity and were better than IgE reactivity to a crude extract of Aspergillus. Furthermore, in ABPA patients studied during periods of remission the IgE reactivity to Asp f3 and f4 remained significantly elevated compared with Af ST+ non‐ABPA patients. The IgE responses when considered either to be positive or negative to Asp f3 and f4 significantly differentiated ABPA from Af ST+ and ST− non‐ABPA CF patients. In contrast, IgE reactivity was considered positive to the crude extract in 89% of ABPA, 61% of Af ST+, and 0% of Af ST− non‐ABPA CF patients.

Conclusions:  Immunoglobulin E reactivity to a panel of purified Af allergens, especially to Asp f3 and f4, differentiates ABPA from atopic Af ST+ non‐ABPA CF patients. Serial determinations of IgE reactivity to individual purified Aspergillus antigens, especially Asp f3, demonstrates that increases in IgE reactivity may provide improved distinction between stages of flares and remission compared with changes in IgE reactivity to a crude Aspergillus extract.
NEW METHOD OF MEASURING THE AVERAGE THERMAL VELOCITY OF ATOMS
Authors: Stein T. S. , Carrico J. P. , Lipworth E. , Weisskopf M. C.
Published: February 2004

The average thermal velocity of atoms in an atomic-beam apparatus is measured using the velocity-dependent interaction μ lim →·[(v lim →/c)× E lim →].
CHARACTERISTIC IONIZATION LOSSES OBSERVED IN AUGER EMISSION SPECTROSCOPY
Authors: Bishop H. E. , Rivière J. C.
Published: February 2004

Peaks in the differential energy distribution resulting from losses of the type (Ep − E1), where Ep is the primary energy and E1 is the critical ionization potential of an inner atomic shell giving rise to a strong Auger transition, have been observed during Auger emission spectroscopy. In the example presented, characteristic loss peaks due to ionization of the boron and carbon K shells are shown. Loss peaks are usually of the same order of magnitude as some of the smaller Auger peaks, and care should be taken in identification, under certain conditions of analysis, that the two are not confused.
MAGNETO-OPTICAL PROPERTIES OF A GREEN ROOM-TEMPERATURE FERROMAGNET FeF3
Authors: Kurtzig A. J. , Guggenheim H. J.
Published: February 2004

Ferric fluoride (FeF3) is a transparent green uniaxial weak ferromagnet (canted antiferromagnet) with a Curie temperature of 365 °K. FeF3 is far more transparent in the visible and uv than any other known material which has a spontaneous magnetic moment at room temperature. FeF3 at room temperature has 6 absorption bands between 7000 Å and the band edge which is at 2440 Å. There is a local absorption minimum of α = 4.4 cm−1 in the green at 5225 Å. The Faraday rotation is 180 °/cm at 5225 Å and increases to 1100 °/cm at 3000 Å. The birefringent phase retardation at 5200 Å is about 80 000 °/cm. The two indices of refraction are about 1.54 in the visible spectrum.
SELF-PULSING IN THE He–Cd LASER
Authors: Faxvog F. R. , Willenbring G. R. , Carruthers J. A.
Published: February 2004

Observation of self-pulsing in a helium-cadmium laser is reported in which two running pulses are present inside the cavity. The beat frequency between the two pulses is more stable as the number of modes is decreased, and is very regular at about 8 kHz when only two modes are present within each of the two main spectral peaks of the natural-cadmium active medium.
THE MECHANISM OF GAIN DEPRESSION IN CONTINUOUS-STRIP ELECTRON MULTIPLIERS
Authors: Klettke B. D. , Wilcock W. L. , Mueller R. K. , Wolber W. G.
Published: February 2004

A theory of high-output-current gain depression in continuous-strip electron multipliers is based on the assumption that for a particular device the local gain is a function solely of the local axial field. Substantiative experimental data are presented.
ROLE OF THERMAL EFFECTS AND FAST FLOW POWER SCALING TECHNIQUES IN CO2–N2–He LASERS
Authors: Hill Alan E.
Published: February 2004

Studies of thermal effects in a multi-Joule pulsed CO2 laser indicate that the average power is limited because the equilibrium gas temperature rises with increasing rep rate (or average power input), thereby thermally populating the CO2 (010) level. It is shown that helium primarily heat-sinks the gas. Suitably low gas temperatures can be maintained throughout high pressure, large cavity volumes by exchanging the gas in times shorter than the wall diffusion time. Under such conditions, a linear power scaling-mass flow relationship of 35 kW/lb mass/sec has been attained. A 1-m fast flowing cw device currently produces in excess of 2 kW average in oscillator configuration.
LASER DOPPLER VELOCITY MEASUREMENT WITHOUT DIRECTIONAL AMBIGUITY BY USING FREQUENCY SHIFTED INCIDENT BEAMS
Authors: Mazumder M.K.
Published: February 2004

A simple laser Doppler heterodyning system has been developed where velocities in any set of orthogonal axes can be measured without the directional ambiguity of 180°. The method employs a two-incident-beam heterodyning system where the two incident beams used are of different frequencies. This is accomplished by using a rotating diffraction grating or by employing a Bragg cell. The Doppler signal from the moving scatterer is no longer an ``even'' function of velocity and the frequency bias can be adjusted depending on the maximum value of the velocity to be measured.
STABILIZATION OF He–Cd LASER
Authors: Hernqvist K. G.
Published: February 2004

A helium-cadmium laser using cathaphoretic transport and a diffusion return path is described. It is shown that there exists a critical temperature range for the condenser where the excessive radiation noise of He–Cd lasers is effectively reduced.
CO2 LASER MODULATION BY HOLE INJECTION IN n-TYPE InSb
Authors: Benoit J.
Published: February 2004

Light absorption by injected holes in n-type InSb near liquid nitrogen temperature is used to modulate the CO2 laser. A P+ N junction device is described which achieves a good modulation efficiency up to a few megahertz with a driving power of 300 mW. Such a modulator can be controlled by applying an external dc magnetic field.
CONVOLUTION AND CORRELATION IN REAL TIME WITH NONLINEAR ACOUSTICS
Authors: Quate C. F. , Thompson R. B.
Published: February 2004

We propose a method for obtaining the convolution, and correlation, of signals in real time through the nonlinear interaction of two acoustic waves in ferroelectric crystals. The experimental results presented here for the convolution of two 1350-MHz signals indicate that the strength of the interaction is sufficient to provide new signal processing devices.
IMPROVED POLARIZATION HOLOGRAPHY
Authors: Politch J. , Shamir J. , Uri J. Ben
Published: February 2004

Using circularly polarized light, high-quality holograms can be obtained, containing information on the polarization characteristics of the object. A theoretical derivation and some experimental demonstrations are given.
MAGNETIC-FIELD DIP MEASUREMENTS ON THE He–Cd LASER
Authors: Dienes A. , Sosnowski T. P.
Published: February 2004

We have measured the width of the zero-magnetic-field power dip for the 4416-Å transition of the He–Cd laser. The width is proportional to the decay rate of the electric quadrupole moment, γa(2), of the upper laser level. γa(2), which is of the order of 1 MHz, was found to vary linearly with He pressure. This variation is attributed to MJ-mixing collisions with He atoms. The value of the ``alignment'' cross section σHe(2) is estimated from the slope of this pressure dependence. The decay rate was also found to depend on the Cd density in the discharge. This dependence is tentatively attributed to deexcitation and MJ-mixing collisions with electrons.
ELECTROMIGRATION IN SINGLE-CRYSTAL ALUMINUM FILMS
Authors: d'Heurle F. , Ames I.
Published: February 2004

Electrical open circuits can be produced in current-carrying polycrystalline aluminum thin film conductors as a result of electromigration phenomena. In this study, attempts have been made to induce such open circuits in comparable single-crystal aluminum thin-film conductors. It has not been possible to do so even after subjecting the latter to relatively high current densities for more than 10 000h. This observation adds strong support to the previous inference that the formation of electromigration-induced open circuits in polycrystalline aluminum thin film conductors is caused predominantly by diffusion along grain boundaries.
ION IMPLANTATION DEPTH DISTRIBUTIONS: ENERGY DEPOSITION INTO ATOMIC PROCESSES AND ION LOCATIONS
Authors: Brice David K.
Published: February 2004

A useful method of calculating the energy/unit depth deposited in atomic processes by energetic ions in solids is presented. The calculated energy density is shown to correlate well with previous Monte Carlo calculations of the vacancy concentration resulting from ion bombardment and recent experimental measurements of the depth distribution of ion damage. The method also provides the depth distribution of ions in the solid as a function of their energy during the stopping process. This information would allow, for example, calculation of the location and rate of various energy-dependent interactions between incident ions and host atoms.
SPIN-WAVE EXPERIMENTS: PARAMETRIC EXCITATION OF ACOUSTIC WAVES AND MODE-LOCKING OF SPIN WAVES
Authors: Wang S. , Hsu Ta-lin
Published: February 2004

In a spin-wave instability experiment, a YIG disk was bonded onto a quartz rod with a transducer attached to it, and was placed in a microwave cavity in a parallel-pumping arrangement. For microwave power above the threshold for spin-wave instability, parametric generation of acoustic waves was observed. The generation was evidenced by the simultaneous appearance of a low-frequency oscillation in the reflected microwave power and at the transducer. In a subsequent experiment, a low-frequency acoustic wave was sent into YIG through the transducer. A great enhancement of the oscillation in the reflected microwave power was observed. The enhancement was due to phase-locking of spin-wave modes.
SHOT NOISE IN JOSEPHSON POINT CONTACTS
Authors: Kanter H. , Vernon F. L.
Published: February 2004

Experimental evidence is presented showing that the noise in Josephson point contacts is shot noise limited. Comparison with theory indicates that the pair current contribution is not as large as predicted.
CARBON MONOXIDE CHEMICAL LASER UTILIZING A FAST FLOW SYSTEM
Authors: Wittig Curt , Hassler J. C. , Coleman P. D.
Published: February 2004

Lasing from chemically formed CO in the range 5.20–5.60 μ m has been observed in a fast flow (∼ 120 m/sec) system. Atomic oxygen was formed in an O2–He discharge and passed into the optical cavity where it reacted with CS2. The chemical reaction and excitation mechanism are discussed and compared to systems in which flash photolysis was used with CS2–O2 mixtures. Power levels of the order of 0.1 W from an interaction region 10 mm i. d. ×30 cm long were obtained with an input energy of 3 J per pulse into the O2 dissociator.
SIMULTANEOUS OSCILLATION ON TWO ISOTOPIC LINES IN CO2 AND N2O LASERS
Authors: Schoen L. J. , Ronn A. M.
Published: February 2004

The intensity of emission of a CO2 laser has been studied as a function of mole % of 13CO2. It was observed that over the range 1.1 to 56.1 mole % 13CO2 the integrated intensity did not change to within the ± 10 % accuracy of the measurement. Laser action switched from the 13C to the 12C species as a smooth function of mole % of the isotopic species; simultaneous oscillation of both systems was observed over a fairly wide concentration range. The intensity of an N2O laser was studied under identical conditions over the range 95 –1.1 mole % of 14N15NO. The integrated intensity was observed to oscillate erratically with varying percentage of 14N15NO. Laser action was not a smooth function of species concentration.
NONRESONANT ABSORPTION OF ELECTROMAGNETIC WAVES IN A HIGH-DENSITY PLASMA
Authors: Lisitano G. , Fontanesi M. , Sindoni E.
Published: February 2004

Efficient radio frequency (rf) heating of a high-density plasma is obtained for any value of the containing magnetostatic field larger than that corresponding to electron cyclotron resonance.
SHORT-RANGE ORDER IN AMORPHOUS GeTe FILMS
Authors: Dove D. B. , Heritage M. B. , Chopra K. L. , Bahl S. K.
Published: February 2004

Thin films of amorphous (stoichiometric) GeTe have been examined by direct recording of electron diffraction, and intensity profiles across the diffuse diffraction pattern have been recorded with electrostatic rejection of inelastically scattered electrons. Radial distribution analysis of these curves shows that the local order is not characteristic of the distorted rocksalt structure of bulk GeTe, i.e., nearest-neighbor distance of 2.99 Å and nearest-neighbor coordination of 6. Instead it is found that the nearest-neighbor distance is 2.65 Å with coordination of approximately 4. This result is of significance for the interpretation of the electronic properties of amorphous films.
HIGH-SPEED SPECTROSCOPY USING THE INVERSE RAMAN EFFECT
Authors: McLaren R. A. , Stoicheff B. P.
Published: February 2004

A method of obtaining inverse Raman spectra over the range of frequency shifts ∼ 300–3500 cm−1 in liquids and solids in a time of ∼ 40 nsec is described. The stimulating monochromatic radiation at 6940 Å is provided by a giant-pulse ruby laser; the background continuum is the short-lived spontaneous fluorescence of rhodamine B or 6G excited by second-harmonic radiation (3470 Å) produced in KDP from a small part of the main laser beam, thus ensuring simultaneous irradiation of the sample by both beams.
ULTRAVIOLET LASER EMISSION OF ORGANIC LIQUID SCINTILLATORS USING A PULSED NITROGEN LASER
Authors: Broida H. P. , Haydon S. C.
Published: February 2004

Optical pumping and strong laser ultraviolet emissions of organic scintillator solutions have been achieved with a pulsed N2 laser emitting at 3371 Å. Conversion efficiencies up to 25% and power outputs up to 10 kW have been obtained over the range between 3550 and 4800 Å from a variety of organic scintillator molecules in several solvents.
SELF-STABILIZATION AND NARROWING OF OPTICAL PULSES FROM GaAs JUNCTION LASERS BY INJECTION CURRENT FEEDBACK
Authors: Paoli Thomas L. , Ripper José E.
Published: February 2004

Self-induced intensity pulsations of continously operating GaAs junction lasers have been frequency-stabilized and narrowed by regenerative feedback of oscillations in the injection current. The spectral width of the pulse rate has been reduced by a factor of 20 to less than 30 kHz while the optical pulse width was reduced by at least a factor of 2 to less than 180 psec. These results suggest that a well-stabilized source of short optical pulses can be constructed from GaAs injection lasers without external microwave circuitry.
ELECTRON BEAM DETECTION OF CHARGE STORAGE IN MOS CAPACITORS
Authors: Huber E. E. , Cohen M. S. , Smith D. O.
Published: February 2004

A method for destructive detection of the state of charge storage in a metal-SiO2-Si capacitor is presented. This method is based on the modulation by the charge of the efficiency of separation of electron-hole pairs which are generated by the penetration of an electron beam into the capacitor.
PROPAGATING MAGNETOELASTIC WAVES IN AN INFINITE PLATE
Authors: van de Vaart H. , Matthews H.
Published: February 2004

The elastic modes of propagation in an infinite plate are coupled to the propagating magnetostatic modes when the plate material is magnetoelastic. The dispersion relations for these magnetoelastic modes are derived, and the resulting coupled mode spectrum is discussed.
RELATIVE SIGNS OF NONLINEAR OPTICAL COEFFICIENTS OF POLAR CRYSTALS
Authors: Miller Robert C. , Nordland William A.
Published: February 2004

A determination of the relative signs of the nonlinear optical coefficients that give rise to second harmonic generation has been made for each of the following crystals: LiNbO3, LiTaO3, BaTiO3, ZnO, and LiGaO2. It is found that d33 and d31 have the same signs in LiNbO3, LiTaO3, BaTiO3, and LiGaO2. In ZnO, LiGaO2, and LiTaO3, the ratios d33/d31, d33/d32, and d31/d22, respectively, are negative.
ROLE OF HYDROGEN IN POLARIZATION REVERSAL OF FERROELECTRIC Ba2NaNb5O15
Authors: Singh S. , Levinstein H. J. , Van Uitert L. G.
Published: February 2004

By field-annealing barium sodium niobate crystals in the presence of H2O and D2O vapor it is established that protons diffuse into the crystals. As a result of this diffusion, the crystal resistivity is found to increase by a factor of ∼2×103. It is concluded that diffusion of protons into ferroelectric barium sodium niobate and other high-temperature ferroelectrics is necessary before the crystal dipole moment can be freely reversed by an external electric field.
RECOMBINATION WAVES IN Au-DOPED Si
Authors: Bisio G. R. , Chiabrera A. E.
Published: February 2004

Theoretical computation of recombination waves in Au-doped Si is reconsidered introducing new expressions of the carrier lifetimes, deduced from a linearized theory of the generation-recombination process kinetics. The comparison with previous theoretical and experimental papers is given. The role of the temperature and dc electric field on the instability condition is examined.
MEASURED ELECTRICAL CHARACTERISTICS OF INTERDIGITAL SURFACE WAVE TRANSDUCERS ON LITHIUM NIOBATE
Authors: de Klerk J. , Daniel M. R.
Published: February 2004

The radiation resistance and reactance as a function of frequency has been measured for interdigital comb structures used for generating z propagating surface waves on a yz surface of LiNbO3. The quantities reveal a basic asymmetry about the center frequency of surface wave generation due to the simultaneous launching of bulk waves.
FORMATION OF VACANCY PITS ON THE SURFACE OF METALS ON QUENCH ANNEALING
Authors: Tariyal B. K. , Ramaswami B.
Published: February 2004

Pits appear on the electropolished surface of Al-0. 0045 % Sn alloy on quenching in liquid nitrogen followed by annealing at room temperature. These pits exhibit all the features of vacancy pits, which appear on cooling from high temperatures. It is suggested that these pits form by the migration of excess vacancies from the interior to the surface, and by the nucleation of pits at the sites of nonhomogeneity at the oxide-metal interface.
CURRENT CAPACITIES OF SUPERCONDUCTING V3Ga TAPES IN HIGH MAGNETIC FIELDS
Authors: Tachikawa K. , Iwasa Y.
Published: February 2004

Current-carrying capacities at 4.2°K of various superconducting V3Ga tapes produced by a new diffusion process have been measured in transverse magnetic fields up to 215 kG. Effects of heat-treatment temperature and addition of zirconium are presented.
INFRARED PHOTOEMISSION FROM SILICON
Authors: Martinelli Ramon U.
Published: February 2004

Infrared photoemission from p-type silicon has been observed with a threshold of 1.1 eV. The surface of the sample has been activated to a state of effective negative electron affinity. The escape depth for thermal photoelectrons is 5.5μ (microns) and surface escape probability is 0.18.
COHERENT OPTICAL DETECTION OF ULTRASONIC IMAGES USING ELECTRONIC SCANNING
Authors: Green P. S. , Macovski A. , Ramsey S. D.
Published: February 2004

Visualization of ultrasonic wavefields incident on an optically reflecting surface is effected by coherent optical detection of the deformations of this surface. A Twyman-Green interferometer is used in which the orthogonal reference beam is frequency-offset with an ultrasonic light modulator. The recombined light field is scanned with an image dissector, and the resulting image displayed on a kinescope.
LARGE-AMPLITUDE CURRENT OSCILLATIONS IN n-TYPE Ge
Authors: Guion W. G. , Ferry D. K.
Published: February 2004

Threshold average electric fields of approximately 1 kV/cm are experimentally observed for large-amplitude sinusoidal current oscillations at 77°K. These oscillations are different from previously reported oscillations in n-type Ge. The 0.25–1.0 A (rms) oscillations occur at frequencies near 1 GHz. The frequency is found to decrease with increasing electric field and to be relatively independent of magnetic field.
SPATIAL MODULATION OF LIGHT USING SURFACE WAVES IN AN INTERFEROMETER
Authors: Hunsinger Bill J. , Holshouser D.
Published: February 2004

An optical phase grating has been generated by introducing surface waves on one face of a Fabry-Perot interferometer. This device called SWIM (Surface Wave Interference Modulator) produces a diffraction pattern at the Fourier plane in which the light intensity of the first-order modulated beam is 1% of the zeroth order with an acoustic power of 0.85 mW/mm beam width. First-order intensities greater than 10% have been realized; however, the process is not linear at this modulation depth.
EFFICIENT INTERNAL OPTICAL PARAMETRIC OSCILLATION
Authors: Ammann E. O. , Yarborough J. M. , Oshman M. K. , Montgomery P. C.
Published: February 2004

Efficient internal optical parametric oscillation has been obtained using a LiNbO3 crystal inside the resonator of a continuously pumped repetitively Q-switched 1.06μ Nd:YAG laser. Dielectric mirrors are coated directly on the plane-parallel end faces of the crystal, and no focusing optics are used inside the laser. The oscillator operates near degenerate with outputs near 2μ. Average output powers as high as 350 mW and 75 % depletion of the available pump power are observed. This represents an order of magnitude larger output power than previously reported for a parametric oscillator. Internal oscillation causes stretching of the laser pulses to as much as five times the normal length, with corresponding increases in oscillator pulse length. Operation of this internal oscillator is compared to that of a similar external oscillator pumped by the same laser.
NONLINEAR OPTICAL EFFECTS USING A CO2 LASER AND A KLYSTRON
Authors: Corcoran V. J. , Cupp R. E. , Gallagher J. J. , Smith W. T.
Published: February 2004

Sum and difference frequency signals have been generated and propagated by mixing CO2 laser and millimeter wave klystron outputs in a gallium arsenide loaded waveguide. As a result, coherent signals that are tunable over the tuning range of a klystron are available in the infrared region.
TEMPERATURE DEPENDENCE OF PRODUCTION RATE OF DIVACANCY AND NEAR EDGE ABSORPTION IN Si BY FISSION NEUTRONS
Authors: Cheng L. J. , Lori J.
Published: February 2004

The production rates of the 1.8-μ absorption band and the near edge absorption in Si irradiated by fission neutrons in the temperature range from 145 to 300 °C were studied. The results indicate that for both the divacancy and the defects causing the near edge absorption, the annealing behavior during irradiation in this temperature range is the same as that after an irradiation at 50 °C.
ONE-WATT AVERAGE SECOND HARMONIC POWER WITH A REPETITIVELY Q-SWITCHED Nd: YAG LASER
Authors: Stein Alexander , Kaplan Robert A.
Published: February 2004

A repetitively Q-switched Nd: YAG laser has been operated with an intracavity second harmonic generator to produce 1-W average power at 0.53 μ. The output coupling optimization of this system has been determined from a simplified model and the results of a computer solution are presented, and compared with the optimization condition for the cw mode of operation. Finally, the dependence of the average output power for the Q-switched mode of operation on the pulse rate is calculated and compared with experimental data.
HIGH-SENSITIVITY ELECTRON SPECTROMETER
Authors: Huchital D. A. , Rigden J. Dane
Published: February 2004

A new type of retarding potential difference electron spectrometer using spherical grids is described. The unique feature of the analyzer is a post monochromator section which selectively collects electrons passing the retarding grids with minimum kinetic energy. Factors affecting the resolution of the analyzer are discussed and a comparison with several other spectrometers operating in the resolution range of 0.05% is presented. An application to x-ray photoelectron spectroscopy is presented.
ZnO LASER BY ELECTRON BEAM EXCITATION
Authors: Iwai Sohachi , Namba Susumu
Published: February 2004

The wavelength of laser emission from an electron-beam-pumped ZnO was measured in the temperature range from 82 to 250°K. The laser emission occurred near the line due to the annihilation of a free exciton assisted by one LO phonon at 82°K. Above 180°K the laser emission occurred near the line due to the transition assisted by two LO phonons. From 130 to 170°K the laser oscillation appeared in two spectral lines. The temperature dependence of threshold current density measured from 82 to 250°K was weak compared with the theoretical curve based on the laser action involving the A-LO line.
THERMALLY SELF-INDUCED PHASE MODULATION OF LASER BEAMS
Authors: Dabby F. W. , Gustafson T. K. , Whinnery J. R. , Kohanzadeh Y. , Kelley P. L.
Published: February 2004

Self-phase modulation of laser beams by media which possess a temperature-dependent refractive index gives rise to far-field aberrational rings. Steady-state aberration profiles were measured and quantitative agreement with theory was obtained. A simple qualitative explanation of the ring structure is given. A self-induced frequency modulation of 1.5-W argon laser pulses was also observed and chirping detected.