Slope Transition Research Articles

Anomalous hyperfine splitting of 57Fe in α-quartz

The hyperfine splitting of 57Fe for substitutional Fe 3+ in synthetic α-quartz was found to increase monotonically with increasing slope of the fine structure transitions exceeding the free ion value several times in highly anisotropic regions. A tentative explanation for this hitherto unreported effect is proposed.

Zero stress strength reduction and transitions in static fatigue of fused silica fiber lightguides

This study shows that the transition in slope of static fatigue (log fracture stress vs. log time to failure) of fused silica fibers, is an intrinsic property of the glass which is modified by the presence of coating materials. The transition for fibers in water at 90°C occurs in the 300–400 Ksi range and is characterized by a change in slope and intercept. The slopes and intercepts preceding the transitions are dependent upon zero stress soak time in water at 90°C, however in the transition region they are unchanged by this treatment. At a stress level of about 160 Ksi the transition region appears to terminate in a more normal fatigue dependence. This may possibly be a fatigue limit. These observations suggest that changes will be required in the theories correlating static fatigue with crack growth parameters as determined from macro-crack experiments. Long-term extrapolations of fatigue data will accordingly have to incorporate modifications based on such changes.

Community structure and zonation of microalgae and hermatypic corals on a fringing reef flat of magnetic island (Queensland, Australia)

The community structure and zonation pattern of the two dominant benthic components (macroalgae and hermatypic corals) on a fringing reef flat at Geoffrey Bay (Magnetic Island, North Queensland) were investigated quantitatively, using a line transect intercept method. Data collected on species composition, distribution and abundance at three sampling locations on the reef flat were analysed and discussed in relation to the prevailing environmental factors.Two major communities are recognized: an Inner Sedimentary Accumulation community, and a Reef Flat community. Within the latter, several ecological units are distinguished in a seawards sequence: an Inner Reef Flat facies, a Middle Reef Flat facies and a Reef Flat-Reef Slope transition zone. Each of these units corresponds to particular morphological, sedimentological and hydrodynamic conditions which determine the distribution of species and species groups on the reef flat.Macroalgae are the dominant community component, by virtue of their widespread distribution and high abundance. In contrast, corals are restricted to the outer reef flat and seagrasses mainly to the inshore sedimentary substrates both being of relatively minor importance as structural elements in the communities. Macroalgal group analysis indicates that the low-growing turf forms are the most significant cover contributors on the reef flat. However, the large fleshy macroalgae, in particular tall Phaeophytes such as Sargassum spp., dominate community structure. The erect calcareous alga, Halimeda opuntia (Linnaeus) Lamouroux is an important component of the algal flora, particularly on the inner reef flat areas, notably contributing to reef sediments. Conversely encrustation on the reef by calcareous algal development is extremely limited.The zonation of organisms on the reef flat at Geoffrey Bay is discussed and compared with that of local (Great Barrier Reef) and other Indo-Pacific fringing reefs. The observed patterns appear typical of fringing reef flats associated with high islands in sheltered conditions.

Effect of fuzzification on the plosive cognition system

Fuzzy algorithms provide a simpler and more powerful approach than statistical decision methods for describing non-ideal (fuzzy) environments in which there exists no precise boundary between the categories due to inherent vagueness rather than randomness. This paper attempts to demonstrate the effectiveness of such an algorithm when applied to the computer recognition of patterns of biological origin such as Telugu unaspirated plosives in initial position of large number of utterances in CVC context. A multieategorizer is described in which the fuzzy processor embodies a fuzzy property extractor and a similarity matrix generator. A provision fur controlling fuzziness in property sets had been made by keeping two parameters. ‘exponential’ and ‘denominational’ fuzzifiers, in the components of property matrices ; their effect on recognition score is also studied. Machines’ performances are explained by plotting curves and through confusion matrices when transition, duration and slope of transition from the ...

Effects of transition length on the perception of stop consonants.

This study investigated the effects of lengthened transitions on the perception of stop consonants. In experiment I, three continua representing the phonetic categories [da] and [ga]containing transitions of 45, 95, or 145 ms were presented to 20 subjects for both labeling and discrimination. Results indicated that although there was a significant change in identification performance from 95 to 145 ms, the shape of the functions, and the locus and slope of the phonetic boundary did not significantly vary across transition lengths. In addition, discrimination of within-category stimulus comparisons was significantly better at the 95-ms transition length than at 45 or 145 ms. In experiment II, the availability of acoustic information was investigated further with the adaptation paradigm. Eight subjects labeled the 45-ms series before and after adaptation with 45-, 95-, and 145-ms [da] stimuli. No effect of transition length was found. These results suggest that the slope and duration of formant transitions seem to contribute minimally to the perception of place of articulation in stop consonants.

Method of optimizing registration signals for electron-beam microfabrication

This paper discusses a way by which registration signals for pattern overlay in a given process environment can be optimized by emphasizing signal transitions and by exploiting an enhancement effect: The slope of signal transitions increases significantly when the separation of adjacent mark edges (mark width) is such that the corresponding complementary signals interfere. The signal-to-noise ratio can be improved even further because more edges can be confined within a given scan window than with conventional configurations with no signal overlap. Experimental results indicate an overall improvement factor of at least 4. The observed enhancement effect is understood on the basis of a simple qualitative model.

Categorical perception of /b/ and /w/ during changes in rate of utterance

Normal sentences containing the sound /w/ were tape recorded and digitized. A normal and a “fast” token of each sentence was stored in a PDP 11-10 computer. The “fast” tokens were created via a pitch-synchronous segmentation program wherein segmentation lines were interactively applied at the zero axis crossing at the beginning of each periodic waveform, and at similar periodic intervals during voiceless speech sounds. Deletion of every third interval resulted in a token of the sentence, increased in rate by one-third. The test consonants plus following vocalic transitions were similarly segmented (11 segments approximately 9 msec each). A recursively applied deletion program allowed alteration of the slope of the CV transitions in 11 steps in both normal and fast utterances. Listeners randomly heard ten presentations of each slope condition for each test sentence at each rate of utterance. Rapid slope changes were heard by listeners as /b/ and more gradual slope changes as /w/. During changes in rate of utterance, the categorical boundary between /b/ and /w/ was shifted toward a steeper slope. The results of this study are discussed in regard to the temporal relativity of categorical boundaries.

Perception of /w, r, l, y/ by normally articulating and misarticulating children

Three ten-step series of synthetic speech stimuli were constructed: /ræm/ to /læm/, /ræm/ to /wæm/, /læm/ to /yæm/. Within each series, differences consisted of variations on onset frequency and slope of transition in F2 or F3. These stimuli were presented to 5- to 7-year-old children in identification (picture-pointing) and 3-step same—different (AX) discrimination tasks. Two groups of subjects were tested: children having normal articulation and children who misarticulated /r/ or /l/. Results support the view that some articulation-disordered children exhibit correlated perceptual deficits. [Research supported by NICHD grant No. HD-00098 to the Center for Research in Human Learning, NIMH grant No. MH-21153 to J.J. Jenkins and W. Strange, and NICHD Contract No. NO1-HD-1-2420 to Haskins Laboratories.]

Calculation of entropies of transition and reaction and slopes of transition and reaction lines using Debye theory

By using sound wave velocity data the entropy changes and dP/dT of 10 polymorphic transitions and solid-solid reactions have been calculated according to Debye theory. These values show systematic deviations from experimentally determined values of the same parameters. This data set allows the application of a correction factor to calculate values for cases where experimental determinations of the phase diagram or entropies are not available but where sound wave velocities are available or can be estimated for all phases. When applied to γMg2SiO4 and γMg2GeO4 disproportionation, the estimated values of dP/dT are +0.016 and +0.027, respectively. The entropy expressions indicate that negative dP/dT for a polymorphic transition implies either anomalously low sound velocities in the high-pressure phase as compared to the low-pressure phase or non-Debye contributions to the specific heat. This is not necessarily the case for disproportionation reactions, as illustrated by γFe2SiO4 and γMg2SiO4.

Heat-flux transitions at low Rayleigh number

The transition to turbulence in the convective flow of air between horizontal plates in a circular convection chamber has been investigated. Measurements of the heat flux and the instantaneous spatial temperature field were made simultaneously for a range of Rayleigh number Ra between 3 × 103 and 5 × 104. Ra could be varied by changing the vertical separation or the temperature difference between the plates. The temperature field was measured with either a horizontal or a vertical array of resistance wires mounted so that the flow field could be traversed at velocities much greater than flow velocities characteristic of thermal convection. Slope transitions in the heat flux were found at Ra = 9600 and Ra = 26000. Many measurements of the instantaneous horizontal distribution of temperature for Ra > RaT2 indicate a growth in amplitude of fluctuations with non-dimensional cyclical wavenumbers of 0·4 and greater. The probability of observing these high wavenumber fluctuations also increases as Ra becomes greater than RaT2. The horizontal wavelengths of the different types of temperature fluctuations are compared with the observations of others.

Poly(Butadiene)/Poly(Styrene) Interpenetrating Polymer Networks

Abstract Interpenetrating polymer networks (IPN's) of poly (butadiene) (PB) and poly(styrene) (PS) were prepared using both random (containing 36 per cent cis, 55 per cent trans, and 9 per cent 1,2 vinyl) PB and high-cis PB. For both series, a wide range of PB/PS compositions were synthesized. Using samples stained with osmium tetroxide, electron microscopical studies revealed an irregular cellular structure of a few hundred A˚ngstrom diameter with the first component, PB, making up the cell walls. The size of the cells was found to depend on the PB crosslink density for the random materials. Modulus-temperature data revealed two distinct glass transitions, confirming the finding of two phases by microscopy. However, the transition temperature and transition slope varied with composition, and with the microstructure of the poly (butadiene), giving evidence of significant molecular mixing. Stress-strain data on the IPN's showed that materials rich in PB behave like self-reinforced elastomers. Charpy impact resistance experiments on materials rich in PS indicated values of 5 ft-lb/in. of notch, which compares well with graft-type polyblends of similar PB/PS composition. The results were interpreted in the light of the recent theoretical work of Bragaw, who considered the importance of the distances between domain boundaries with respect to crack acceleration mechanics. Although the IPN's considered herein exhibited somewhat less than the predicted optimum phase dimensions, the arrangement of the domains is different from ordinary impact resistant plastics.

Polybutadiene/polystyrene interpenetrating polymer networks

AbstractInterpenetrating polymer networks (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepared using both random (containing 36% cis, 55% trans, and 9% 1,2 vinyl) PB and high‐cis PB. For both series, a wide range of PB/PS compositions were synthesized. Using samples stained with osmium tetroxide, electron microscope studies revealed an irregular cellular structure of a few hundred Ångstrom diameter with the first component, PB, making up the cell walls. The size of the cells was found to depend on the PB crosslink density for the random materials. Modulus‐temperature data revealed two distinct glass transitions, confirming the microscopy finding of two phases. However, the transition temperature and transition slope varied with composition, and with the microstructure of the polybutadiene, giving evidence of significant molecular mixing. Stress‐strain data on the IPN's showed that materials rich in PB behave like self‐reinforced elastomers. Charpy impact resistance experiments on materials rich in PS indicated values of 5 ft‐lb/in. of notch, which compares well with graft‐type polyblends of similar PB/PS composition. The results were interpreted in the light of the recent theoretical work of Bragaw, who considered the importance of the distances between domain boundaries with respect to crack acceleration mechanics. Although the IPN's considered herein exhibited somewhat less than the predicted optimum phase dimensions, the arrangement of the domains is different from ordinary impact resistant plastics.

Reflection and breaking of internal waves on a sloping beach

The reflection and breaking of internal waves on a sloping beach were studied in a small wavetank filled with water and petroleum. The dependence of the reflection coefficient of the internal waves on wave steepness and on beach slope is found to be very similar to that of surface waves. The reflection coefficient is small for the very gentle slope, increases rapidly as the slope increases, and becomes almost constant for the steep slope. The reflection coefficient decreases with increase of the wave steepness. Also, the transition slope at which the coefficient curve has the maximum gradient increases with increase of the wave steepness. Breaking pattern of the internal waves is classified into four types; “breaking”, “semi-breaking”, “wrinkle-generating”, and “non-breaking”. Their dependence on beach slope and wave steepness is examined. The regular sequence of the four breaking types from “breaking” to “non-breaking” is observed with decrease of wave steepness or with increase of beach slope.

Middle Pennsylvanian Rocks of Eastern Great Basin

The Atokan and Desmoinesian Series in the eastern Great Basin consist mostly of nine major carbonate rock types ranging from carbonate mudstone through micritic allochemical limestone to grainstone. On the east, in the region of the Oquirrh Formation, orthoquartzites are important, and in some local sections they constitute nearly half the sedimentary sequence. Stratigraphic and petrographic data were combined to define lithofacies which were linked in a paleogeographic pattern and model of sedimentation. Areas demarked by the main lithofacies correspond closely to distribution of lithostratigraphic units recognized in the region: (1) the upper Ely Group, particularly the Hogan Formation, comprises a basin assemblage deposited mostly in relatively deep water; (2) the Bird Spring Group and Callville Limestone represent a transition between a shallow shelf on the east and southeast, and the basin in east-central Nevada and west-central Utah; (3) the Oquirrh Formation is a transitional slope assemblage between the basin and Weber shelf on the east. During the Atokan, the basin was not large, and the central Great Basin region was dominated by shifting conditions resulting from sea level changes superimposed on differentially subsiding areas. Conditions were more regular in the basin during the Desmoinesian Epoch, when the basinal environment expanded southward and eastward. However, in the area of the Oquirrh Formation, periodic subsidence coupled with rapid sea level fluctuations resulted in alternation of orthoquartzite and quiet water calcareous sedimen s. Orthoquartzites in the Oquirrh Formation are polygenetic, but most are considered to have been built westward by shore progradation following pulses of subsidence. Transport down a paleoslope by density currents following subsidence probably was another important means of deposition. Maximum thickening of Middle Pennsylvanian rocks was not in the basin, but in the region encompassed by the Oquirrh Formation as a result of greater subsidence. Determination of the original thickness of the Desmoinesian Series in the central Great Basin is made difficult by probable erosion of all or part of the Desmoinesian record at several key localities. Coupled with this is the difficulty in evaluating amounts of compaction in the predominantly fine-grained sediments of the basin. The Middle Pennsylvanian part of the Bird Spring Group does not show significant thickening. Previous attempts to correlate areas of maximum thickening with environmental centers of deposition have resulted in difficulties in environmental interpretation. Post-Paleozoic structural deformation was not evaluated in this study, although the effects probably were great.

Environmental fatigue crack propagation of aluminum alloys at low stress intensity levels

Environmental fatigue crack propagation in 2024-T3, 7075-T6, and 7178-T6 has been studied at low levels of cyclic amplitude of stress intensity, ΔK. Both wedge force loading and remote loading techniques were employed to achieve the desired ΔK levels, and preliminary experiments were designed to test their compatibility. Testing was carried out in humid air, distilled water, and 3.5 pct sodium chloride solution, and the observed crack growth rates compared with those in desiccated air. Later studies were also conducted in an inert reference environment with a total water content of less than 2 ppm. When the data are plotted as log ΔK vs log d2a /dN, alloy 2024-T3 exhibits a marked slope transition, alloy 7075-T6 a slight slope transition, and alloy 7178-T6 a rectilinear behavior throughout the whole range of ΔK studied. The basic shape of these curves is discussed in terms of state-of-stress conditions at the crack tip, frequency effects, environmental effects, strain rate sensitivity, and metallurgical structure. An attempt is also made to correlate the rate of fatigue crack propagation in a particular environment and at a particular ΔK level with the fracture topography.

Extension of Coincidence Limiting Frequency Range in Ferrimagnets

Power limiting using the first-order spin-wave instability has been observed in a ferrimagnetically coupled filter-limiter at higher frequencies than had previously been believed possible. For example, a filter-limiter, using orthogonal strip-line resonators coupled by the dipolar fields of a YIG sphere, was constructed at 4000 Mc. Output power was limited with the sharp break at the threshold and flat limiting curve characteristic of coincidence limiters. This result is in contrast with the operation of similar limiters at this frequency which use the second-order spin-wave instability in which the limiting characteristic has a much more gradual slope transition above the threshold. Coincidence limiters have previously been believed to have a maximum operating frequency ωc=2ωMNT (3.27 kMc for a YIG sphere) since, with an isolated sample, coincidence of the uniform precession resonance and the subsidiary absorption occurs only for ω<ωc. These results are observed for a coupled mode resonance in these ferrimagnetically coupled circuits which occurs for dc magnetic field values in the subsidiary absorption region below the uncoupled uniform precession value (ω/γ). It is found that a minimum value of the circuit-sample coupling is required to observe this extension of coincidence type limiting. Limiting thresholds as low as −10 dBm have been observed with the strip-line circuit and lower levels are believed to be possible. Wide low-level bandwidths (>10%) are also obtained with these circuits, but with an increase in the limiting threshold. The above results are explained by computing the normal modes of the microwave-ferrimagnetic resonator circuit. It is found for tight enough coupling that one of the branches of the normal mode spectrum is in coincidence with the subsidiary absorption at a higher frequency than the uniform precession resonance. The usual coincidence limiter operation (ω<ωc) is thus the small coupling case of the more general type of operation.

Pulmonary extravascular water volumes from transit time and slope data

In single injection indicator-dilution experiments in the heart-lung system of anesthetized dogs, labeled water has a significantly greater distribution volume than simultaneously injected Na22 or T-1824, which have nearly identical concentration-time curves. Values for needle-to-needle vascular and aqueous compartments are calculated from the blood flow and the appropriate mean transit times. Values for the extravascular pulmonary water compartment, obtained by difference, are of the order of 4.3 ml/kg body wt. Similar calculations from the slope volumes (Newman et al., Circulation 4: 735, 1951) provide values of the order of 3.0 ml/kg body wt. The approximate concordance of the two sets of values is not considered validation of the slope calculation, which remains without an anatomically defined basis. Other limitations of the experimental procedures and calculations are considered. The value of 4.3 ml/kg body wt. obtained by the transit time calculation is considered to provide an upper limit to the volume of pulmonary tissue water involved in gas exchanges. Submitted on September 12, 1961

PEDIMENT MORPHOLOGY IN CHUGOKU MOUNTAINS SOUTHWESTERN JAPAN

At the lower margins of steep slopes forming three levels of erosion surfaces in Chugoku mountains there developes pediment topography. The longitudinal width of the pediment is about 1500m and their inclination is from 7° to 9° in most cases. The more marginal a pediment is, the more gentle is the inclination. The pediments are covered with strata of cobbles, boulders and coarse sands, but in those strata bedding and sorting are not remarkable. The inclination of escarpments behind is 24° to 30° or 35° in rare occasions. Transitional slope between the escarpments and the pediments are zonal. The escarpment foot has not a zigzag outline but a straight one. The developments has already stopped and they have been dissected by streamlets. In Chugoku mountains pediments are mostly found on granite area with hardrock cover, where local base-level was rather stable and relief was rather high. All pediments are on granite and a part or all of back hill in formed with hard rocks. Though all districts where pedimants can develop have a similar climatic condition, actual development of pediment is distinctly controlled by kinds of rocks. It seems that the collapse of granite is more similar to that of rocks under arid or semiarid climate than other rocks. The pediments are formed by parallel retreat of escarpment, which is caused by weathering, gravitation and rainfall. And, they are modified by sheet wash. It can not be known under what climatic condition the pediments develop. Inferring from the strata on, the pediments, the climate must have been more arid than that of the present.

The effect of recirculation on the shape of the arterial concentration curve after an instantaneous injection of indicator

We present our observations on 15 patients at cardiac catherization showing by two-site sampling that recirculating indicator begins to influence the downslope on the cardiac output curve from 1 to 9 sec before the point of obvious recirculation. The concentration points of the last 38 per cent of the exponential portion of the downslope were slightly increased resulting in a decreased slope. The result is a false low value for the cardiac output estimated at 1·2 ± 1·5 per cent. This is well within the limits of tolerance for the method and less than that proposed on theoretical basis by other investigators. The total error is probably greater when the injection is made into a vein rather than into the heart because of the slower rate of decline of the downslope, but insufficient data are available in this study for statistical evaluation. A comparison was made of the various portions of the arterial concentration curves. The vein-right ventricle, right ventricle-brachial artery, and vein-brachial artery arterial concentration curves are compared as to appearance time, peak concentration time, mean transit time, cardiac output, and central volume as measured by both the mean transit time and slope method. This comparison shows that the cardiac output measurement as calculated from the vein-right ventricle curve and right ventricle-brachial artery curve are larger than that calculated from an arterial concentration curve of the circulation from vein-brachial artery. The values of the central volumes by the MTT method of these two portions of the circulation when summed average slightly larger than that measured by the vein-brachial artery curve.