Positions Of Troughs Research Articles

A Conceptual Synoptic Model Approach to the Development of a Precipitation Climatology as Applied to Montreal, Quebec

Abstract This study documents the frequency and intensity of precipitation at Montreal, Canada, from 1979 to 2018 as it relates to four quadrants of a 500-hPa wave, identified by the position of troughs, ridges, and inflection points. These quadrants provide a simplified conceptualization of the contributions from the temperature and vorticity advection forcing terms in the quasigeostrophic (QG) omega equation. Precipitation is found to be significantly more intense in every season except summer in the quadrant immediately upstream of the 500-hPa ridge, where differential cyclonic vorticity advection (DCVA) and a local maximum in horizontal warm-air advection (WAA) tend to promote unambiguous QG ascent. In summer, the average precipitation is still most intense in the DCVA-WAA quadrant, but not significantly more than in the quadrant immediately downstream of the 500-hPa trough, where DCVA and a local maximum in horizontal cold-air advection (CAA) are expected to compete, resulting in ambiguous QG vertical motion. Precipitation in the DCVA-CAA quadrant is more intense in every season than in the expected differential anticyclonic vorticity advection (DAVA) quadrants, with significantly higher intensities in spring and fall. Furthermore, the DCVA quadrants exhibit significantly stronger ascent compared to the DAVA quadrants and the DCVA-WAA quadrant features significantly warmer 850-hPa equivalent potential temperatures compared to the three other quadrants in every season. Odds ratios indicate a statistically significant association between heavy precipitation episodes and the DCVA-WAA quadrant. Heavy precipitation episodes in the DCVA-CAA quadrant are associated with a negatively tilted 500-hPa geopotential height pattern in winter and fall. Significance Statement Operational weather forecasters apply conceptual models that connect upper-atmospheric weather patterns to vertical motion and precipitation. However, few studies have quantified this connection over a longer, continuous period of time. In this study, we examine the relationship between historical subdaily precipitation at Montreal, Canada, and a simple large-scale conceptual model that relates vertical motion to the position of upper-level troughs and ridges. We find significant evidence for heavy precipitation to occur upstream of the upper-level ridge, and for very little, or very light, precipitation to occur upstream of the upper-level trough. These results provide quantitative support to some of the conceptual methods available to operational weather forecasters in preliminary analyses that support their precipitation forecasts.

Numerical investigation on the hole characteristics and perforation mechanism of conical liquid sheet

The conical liquid sheet formed by a swirl nozzle was numerically investigated by volume-of-fluid (VOF) in this paper. With increase of Reynolds number (Re), the breakup process of the conical liquid sheet was dominated successively by rim, rim-perforation, perforation, perforation-wave and wave disintegration modes, which agreed well with the experiment results. For the perforation disintegration mode, several kinds of hole in the liquid sheet were successfully predicted, such as isolated holes and group holes. The expansion speed of the hole varied with the time in an exponential form at the initial stage of hole growing, and then kept constant at Taylor-Culick speed. That was the reason why there were two views on the expansion speed of the hole. A model to predict the expansion speed and the rim radius of the hole was proposed and well validated by the numerical results. The flow instability in the conical liquid sheet was successfully predicted, and its wave length was corresponding with Reitz wave instability model. Based on such flow instability, the mechanism of perforation formation was revealed. At the superimposed position of surface wave troughs, fluid migration from this position to its surrounding stretched the liquid sheet thinner and thinner, and finally made it collapsing. Thus, the perforation of the liquid sheet was an intrinsic performance induced by flow instability of liquid sheet itself, rather than the environmental factors. Furthermore, based on the such perforation mechanism, a perforation-time model is proposed, which is reasonable to predict the formation process of hole.

The feasibility of digital guidance drill template assisted expansive open-door laminoplasty

Objective: To explore The feasibility of digital guidance drill templates assisted expansive open-door laminoplasty. Methods: Ten specimens of normal adult cervical spine (C3-7) were selected, including six males and four females. The specimens aged 42-67 years, with an average age of (43.6±4.2) years. After CT scanning, the date was imported into Mimics software in DICOM format. 3D models were reconstructed and the position and depth of troughs on the open side and hinge side were selected for expansive open-door laminoplasty. Drill templates were designed and exported in STL, manufactured by 3D printing finally. Then drill templates were attached to the posterior part of cervical lamina and spinous process. Under guidance of templates, troughs of both sides were conducted by using a high-speed drill. Then the lamina is elevated and instrumentations were implanted. Postoperative CT scanning was conducted to record the fracture of trough on the hinge side. 3D reconstruction was performed again to compare the position and depth between theory and actual trough on both sides by paired t test. Results: A total of 50 drill templates were designed and manufactured. There was no occurrence of hinge fracture after operation. In C3-7, the distance range between the theory position of troughs on the open side and the midline was 11.8-14.4 mm, while in actual it was 11.4-14.0 mm. The distance range between the theory position of troughs on the hinge side and the midline was 11.6-14.3 mm; in actual, it was 10.9-14.0 mm. The theory depth range of trough on the hinge side was 3.0-3.8 mm, while the actual depth was 3.1-3.8 mm. According to the statistical analysis, the difference in the position of trough on the open side, the position of trough on the hinge side and the depth of trough on the hinge side between theory and actual were not statistically significant (all P>0.05). Conclusion: Digital guided template assisted open-door laminoplasty is a feasible technique, which can improve the accuracy and safety of the position and depth of the trough, and has clinical application value.

Climate Variability of Atmospheric Rivers and Droughts over the West Coast of the United States from 2006 to 2019

Water resources are crucial to the livelihood and sustainability of the general public across the western United States. This study covers the timespan of both the third driest drought in Californian history between 2012 and 2015 as well as the extreme atmospheric river year in 2016–2017. The evaluation of vertical moisture profiles using Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Radio Occultation (RO) data, National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) Reanalysis of 500 hPa geopotential heights, 1000–500 hPa thickness, Optimum Interpolation (OI) Sea Surface Temperature (SST), NOAA/NDBC buoy data, and NASA, MEaSUREs, Gridded Sea Surface Height Anomalies (SSHA) were performed. The daily COSMIC time evolution from 2006 through 2015 showed a flat to slightly upward trend of both temperature and water vapor profiles through the entirety of the western US drought. Subsequently, a significant increase of temperatures and water vapor were recorded in early 2016 before the extreme Atmospheric River (AR) season of 2016–2017. The quantitative analyses suggest that warmer SST and higher SSHA lead to an increase of heat fluxes from the ocean into the troposphere, which forces thickness changes and thus the position of troughs in the geopotential height field changes afterwards, consequently pushing the trough eastward over the Pacific Northwest and potentially leading to an active AR year in the western US. It appears that regional COSMIC RO moisture profiles, seasonal SST, and SLH anomalies may serve as a precursor for seasonal or sub-seasonal precipitation outlook along the western US.

Characterization of patient inhaler inhalation sounds using non-contact and tracheal microphones

The dose delivery from dry powder inhalers is dependent on user inhalation technique, particularly the peak inspiratory flow rate (PIFR). Non-contact acoustic methods have recently been employed to objectively measure PIFR during inhaler use. This study aimed to further inhaler acoustics research by extracting acoustic features from inhaler inhalation sounds using non-contact and tracheal microphones and correlating these features with PIFR. This study also investigated the repeatability of the position of the peaks and troughs of the inhaler inhalation power spectral density (PSD) profile across patients. The effects of PIFR, inhalation duration, age, gender, body mass index (BMI) and lung function on the PSD profile were also investigated. Fifty three patients (asthma (n = 26), COPD (n = 14) and other respiratory conditions (n = 13), such as obstructive sleep apnea and chronic cough) were recruited for this study. Each patient was asked to inhale at maximal flow rate through a Diskus™ inhaler while non-contact (5 cm from the inhaler mouthpiece) and tracheal microphones recorded the inhalation sounds. A gold standard measurement of PIFR of inhaler inhalations was also measured simultaneously using a spirometer. It was observed that the Shannon entropy (H) of inhalation sounds generated the strongest correlation with PIFR in the non-contact recordings (R2 = 0.82, p < 0.001). The average power (Pave) of inhalation sounds generated the strongest correlation with PIFR in the tracheal recordings (R2 = 0.29, p < 0.001). It was found that the position of peaks and troughs in the PSD profile of inhaler inhalations were more repeatable at an intra-patient level (p < 0.001) and that PIFR, inhalation duration and age had weak significant effects on the inhalation PSD profile (p < 0.01). Non-contact acoustic methods show promising opportunities to objectively monitor patient inhalation technique and respiratory health remotely which may greatly benefit both patients and healthcare professionals.

Dissipative propagation of pressure waves along the slip-lines of yielding material

Traditional slip-line field theory considers steady-state pressure distributions. This work examines the evolution of pressure at yield. We show that, for a two phase material in plane strain at the point of plastic yield of the main constituent, pressure develops according to dissipative wave mechanics. The pressure wave equations are examined in more detail for the special case of radially symmetric plane strain, and for Von Mises and Drucker-Prager yield envelopes. The positions of pressure troughs are compared to the separation of slip-lines formed during the expansion by internal pressurisation of a cylinder of mild steel.

Use of circulation types classifications to evaluate AR4 climate models over the Euro-Atlantic region

This paper presents an evaluation of the multi-model simulations for the 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) in terms of their ability to simulate the ERA40 circulation types over the Euro-Atlantic region in winter season. Two classification schemes, k-means and SANDRA, have been considered to test the sensitivity of the evaluation results to the classification procedure. The assessment allows establishing different rankings attending spatial and temporal features of the circulation types. Regarding temporal characteristics, in general, all AR4 models tend to underestimate the frequency of occurrence. The best model simulating spatial characteristics is the UKMO-HadGEM1 whereas CCSM3, UKMO-HadGEM1 and CGCM3.1(T63) are the best simulating the temporal features, for both classification schemes. This result agrees with the AR4 models ranking obtained when having analysed the ability of the same AR4 models to simulate Euro-Atlantic variability modes. This study has proved the utility of applying such a synoptic climatology approach as a diagnostic tool for models’ assessment. The ability of the models to properly reproduce the position of ridges and troughs and the frequency of synoptic patterns, will therefore improve our confidence in the response of models to future climate changes.

New data on the structure of the central part of the White Sea paleorift system

Complex geological and geophysical data obtained during recent research by the Marine Arctic Geological Survey Expedition OJSC (MAGSE) indicate that the Riphean Chapoma graben located on the southeastern shore of the Kola Peninsula has its extension under the Gorlo Strait of the White Sea water area and joins the Leshukonsk riftogenous graben as an extended narrow trench in the crystal foundation of the platform. From this it follows that the Chapoma graben is the central segment of the White Sea paleorift system. Only the northwestern edge and probably the upper part of the graben section outcrop on the Kola Peninsula, which represents a highly elevated block of the platform foundation. To emphasize the unity of this paleorift zone, it makes sense to call it the Chapomo-Leshukonsk Paleorift in contrast to the traditional name Kerets-Leshukonsk. The echelon position of the riftogenous troughs of the Chapomo-Leshukonsk paleorift, the form itself of the Leshukonsk and Azopolsk troughs being close to pull-apart assumes their occurrence and development under transtension conditions with elements of the right-side shear along the steep northeastern edges of the grabens.

Potential of the flowing eluent wall and aliquot on-line detection in the OPLC 50 and 100 systems

The flowing-eluent-wall (FEW) procedure is suitable for single and multi-channel on-line overpressured-layer chromatographic (OPLC) separation by operational segmentation of a non-segmented adsorbent bed. One pump only is used to deliver mobile phase and the samples can be injected in parallel on to the non-segmented layer in specific areas determined by the positions of inlet troughs. To prevent mixing of samples from adjacent lanes, mobile phase and samples are introduced to the layer at the sample-introduction positions and at the sides, so the bed is divided into active parts, where separation is performed, and non-active parts, where there is no separation. The FEW arrangement can be used at the inlet (FEW-I) or at both inlet and outlet (FEW-I/O) enabling separate detection and collection of the separation and FEW lines. The OPLC 50 system with the four-channel FEW-I/O configuration is suitable for fully off-line parallel separations and for four-channel fully on-line separations. One or two-channel ...

Influence of lee waves on the near‐surface flow downwind of the Pennines

AbstractThe results of a recent field experiment focusing on the near‐surface pressure and flow fields downstream of the Pennines in northern England are presented. The main aim of the experiment is the improvement of wind forecasts downstream of orography. Trapped lee waves commonly occur in westerly flow in this region, and during the experiment there were numerous instances of apparent flow separation, indicating the formation of lee‐wave rotors. The spatial variability of the near‐surface flow in these circumstances is closely linked to the positions of lee‐wave crests and troughs aloft, and appears to be a response to pressure gradients induced by the lee waves. For large‐amplitude waves, it has been possible to demonstrate a correlation between the fractional change of the flow speed across the measurement array (which if large enough may lead to flow separation) and a normalized pressure‐perturbation amplitude.For a group of lee‐wave cases during which the cross‐mountain flow is strong, a rapid decrease in the Scorer parameter within the lower portion of the troposphere appears to be a prerequisite for rotors to form. However, this does not guarantee their occurrence. For a fixed Scorer‐parameter profile, idealized two‐dimensional simulations indicate that the lee‐wave‐induced pressure‐perturbation amplitude, and hence the occurrence of rotors, is controlled largely by the strength of the wind upstream close to the mountain‐top level. It seems that the combination of a favourable Scorer‐parameter profile and sufficiently strong low‐level winds is required for rotors to develop. © Crown Copyright 2007. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley &amp; Sons, Ltd.

Effects of Diameter, Length, and Circuit Pressure on Sound Conductance Through Endotracheal Tubes

We evaluated the acoustic frequency response of endotracheal tubes (ETs) to assess their effect on respiratory system sound transmission studies. White noise 150-3300 Hz was introduced into 4.0-, 6.0-, and 8.0-mm ETs and recorded at their proximal and distal ends. Four tubes of each size were studied at their original and normalized lengths, in straight and bent configurations, and at circuit pressures from 0 to 20 cmH2O. The characteristics of the sound transmission were compared using an analysis of variance for repeated measures. The average transmission amplitude varied directly with tube diameter. The position of peaks and troughs on the amplitude frequency distribution depended on tube length but not on tube diameter. The angle of the phase-frequency plot correlated well with the length of the tube and was independent of its diameter. A 90 degrees bend in the tube had no effect on its sound transmission. Increasing the circuit pressure above ambient modified the frequency response only if volume changes occurred in the test lung. When used to conduct sound into the respiratory system an ET affects the incident signal predictably depending on its length and diameter but not on its curvature or circuit pressure.

Point load determination of static elastic moduli using laser speckle interferometry

Electronic speckle interferometry (ESPI) is used to determine the Young's modulus E and Poisson ratio ν of an isotropic material. Micron scale deformations of the surface of the block of polymethyl-methacrylate (PMMA) are induced by normal application of a known near-point force. These deformations are recorded in speckle interferometric fringe patterns. An iterative minimum error inversion technique is developed to obtain the elastic properties from the positions of fringe peaks and troughs observed in the fringe patterns. Sensitivity tests of the method on calculated fringe patterns using measured experimental uncertainties suggest the technique will provide measures of the elastic moduli to better than 5%. In an experimental test on a bloc of PMMA (acrylic) the technique gave values of E and ν that differed from corresponding measures obtained using more conventional strain-gauge methods by less than 4%.

Modelling sand wave migration in shallow shelf seas

Sand waves form a prominent regular pattern in the offshore seabed of sandy shallow seas. The positions of sand-wave crests and troughs slowly change in time. Sand waves are usually assumed to migrate in the direction of the residual current. This paper considers the physical mechanisms that may cause sand waves to migrate and methods to quantify the associated migration rates. We carried out a theoretical study based on the assumption that sand waves evolve as free instabilities of the system. A linear stability analysis was then performed on a 2DV morphological model describing the interaction between the vertically varying water motion and an erodible bed in a shallow sea. Here, we disrupted the basic tidal symmetry by choosing a combination of a steady current ( M 0) and a sinusoidal tidal motion ( M 2) as the basic flow. We allowed for two different physical mechanisms to generate the steady current: a sea surface wind stress and a pressure gradient. The results show that similar sand waves develop for both flow conditions and that these sand waves migrate slowly in the direction of the residual flow. The rates of migration and wavelengths found in this work agree with theoretical and empirical values reported in the literature.

Assimilation of IRS-P4 (MSMR) meteorological data in the NCMRWF global data assimilation system

Oceansat-1 was successfully launched by India in 1999, with two payloads, namely Multi-frequency Scanning Microwave Radiometer (MSMR) and Ocean Color Monitor (OCM) to study the biological and physical parameters of the ocean. The MSMR sensor is configured as an eight-channel radiometer using four frequencies with dual polarization. The MSMR data at 75 km resolution from the Oceansat-I have been assimilated in the National Centre for Medium Range Weather Forecasting (NCMRWF) data assimilation forecast system. The operational analysis and forecast system at NCMRWF is based on a T80L18 global spectral model and Spectral Statistical Interpolation (SSI) scheme for data analysis. The impact of the MSMR data is seen globally, however it is significant over the oceanic region where conventional data are rare. The dry-nature of the control analyses have been removed by utilizing the MSMR data. Therefore, the total precipitable water data from MSMR has been identified as a very crucial parameter in this study. The impact of surface wind speed from MSMR is to increase easterlies over the tropical Indian Ocean. Shifting of the positions of westerly troughs and ridges in the south Indian Ocean has contributed to reduction of temperature to around 30‡S.

The Southeast Greenland glaciated margin: 3D stratal architecture of shelf and deep sea

Abstract A seismic stratigraphic study of the Upper Neogene and Pleistocene shelf and deep-sea deposits of Southeast Greenland is presented. The depositional environment was controlled by glacial, turbidity current, and contour current processes. Below the mid- and outer shelf a Tertiary sedimentary wedge, as much as 1.7 km thick, is resting on a seaward-dipping volcanic acoustic basement. A lower marine part is separated by a regional unconformity, SB-A, from two seismic sequences of early Pliocene to Pleistocene prograding clinoforms. SB-A is surmised to represent a seaward-dipping palaeo-relief surface, accentuated by modest submarine erosion related to a sea-level lowering. The overlying two Sequences x and y reflect shelf-edge progradation in front of grounded ice during periods of maximum glaciation. The topset beds of the youngest sequence, possibly of Pleistocene age, are characterized by six or more sub-horizontal, landward-dipping internal unconformities, taken to reflect individual glacial cycles of grounded ice erosion. The present-day shelf is overdeepened, landward dipping, and traversed by troughs. These features are characteristic of a shelf sculptured by grounded ice. The position of the transverse troughs, reflecting the positions of former icestreams, seems to have been more or less permanent since the late Neogene. The shelf progradation has been higher in front of the troughs than in front of adjacent banks, resulting in the development of trough-mouth fans (TMF). The strata continue seawards below the shelf break across a crustal monoclinal flexure to the deep sea. Three seismic sequences have been identified within the late Miocene and Pleistocene deep-sea sedimentary succession on the continental rise. They are bounded by unconformities of mid-Pliocene, early Pliocene, and (?) late Miocene ages. The oldest sequence is interpreted as basin floor fans, probably linked to a sea-level lowstand. The two youngest sequences were deposited from interplay of contour and turbidity currents during glacial periods, and they form large sediment ridges on the sea floor, oriented almost perpendicular to the continental rise, nucleated on the older sequence. Inter-ridge channel-levee complexes recognized within the youngest sequence were deposited from turbidity currents. The major turbidity channels are prolongations of the transverse shelf trough-trough-mouth fan systems. A moat zone, at the base of the continental slope, reflects the position of strong modern contour currents. Appreciable contourite deposition did not commence before the early Pliocene, and was probably linked to glaciation of the shelf and onset or intensification of the Labrador Sea Water deep current.

Perceived location of bars and edges in one-dimensional images: computational models and human vision.

Observers used a cursor to mark the location and polarity of all the bar and edge features seen in compound (f + 3f) gratings of moderate frequency and contrast. They almost always reported six bars and six edges per cycle of the fundamental frequency (f = 0.4 c/deg, contrast 32%), for all phases of the third harmonic (3f = 1.2 c/deg, contrast 10.7%). This general pattern of features was predicted by the positions of peaks and troughs in the outputs of even and odd filters applied to the stimulus waveform, but not by peaks of "local energy" since there were only two energy peaks per cycle. We considered a family of filters whose amplitude spectrum has slope p on a log-log plot. The best-fitting filter slope was determined for bars (even filter) and edges (odd filter) in conjunction with a classification rule in which all peaks and troughs in the response profile are counted as features. If bars were seen at luminance peaks, and edges seen at gradient peaks (zero-crossings in the second derivative) we should have found p = 0 for bars and p = 1 for edges. In fact, for both bars and edges the best-fitting slope was about p = 0.5. For edges, this is consistent with the use of a smoothed (Gaussian) derivative operator. The filters form a quadrature pair, as in the energy model, but features are not constrained to lie at energy peaks. A compressive transducer preceding the filters improved the goodness-of-fit for predicted edge locations, but did not affect the estimate of filter slopes, nor the goodness-of-fit for bar locations. In an experiment with single blurred edges we confirmed that the perceived location of edges is shifted towards the darker side of the edge in direct proportion to the contrast of the edge. This was well predicted by adding a compressive transducer to the filter model.

Seismic expression of depositional sequences associated with expansion and contraction of ice sheets on the northwestern Antarctic Peninsula continental shelf

Abstract We present results from seismic stratigraphical analysis of a regional grid of intermediate-resolution seismic profiles from the Antarctic Peninsula continental shelf that reveal greater complexity in the stratigraphical record than has been previously recognized using lower-resolution seismic records. Widespread unconformities and prograding stratal patterns are interpreted as subglacial erosional surfaces and proglacial depositional systems respectively. Two types of units are recognized, aggrading-shelf units and prograding-slope units. Aggrading-shelf units display minimal slope progradation (less than 2 to 3 km) beyond the pre-existing shelf edge. Units of this type are composed of either acoustically layered prograding foresets or acoustically chaotic seismic facies. Unit thicknesses vary along the shelf from less than 20 ms two-way travel time to more than 200 ms. Low-angle foresets downlap and partially fill palaeotroughs that were formed during prior glacial advances. Foresets are interpreted as proglacial depositional surfaces. The zones of active proglacial deposition were lobate in shape and ranged in width from a few kilometres to more than 30 km. Toplap truncations of foresets result from ice-sheet expansion over proglacial deposits. Glacial erosion on the shelf was concentrated along the axes of ice streams to form deep troughs. Slope progradation occurred mainly near the mouths of these troughs. Prograding-slope units exhibit local slope progradation in excess of 2 to 3 km beyond the location of the pre-existing shelf edge. Shifts in the position of troughs indicate lateral shifts in the positions of ice streams. Hence, sedimentation on the outer shelf and upper slope is point-sourced, not line-sourced, and individual units change from progradational to aggradational along the margin. It is not possible to interpret the ice-sheet grounding history of the shelf using changes in stratal stacking patterns without constraining these lateral changes. However, detailed mapping of prograding-slope units does reveal regional trends that imply glacial periods when greater quantities of sediment were eroded from the shelf and deposited on the slope. We interpret prograding-slope units as having been formed during relatively long-duration glacial expansions. Ice-sheet retreat from the shelf probably occurred rapidly, as indicated by a lack of backstepping proglacial deposits.

Viscous and inviscid flows in a channel with a moving indentation

The flow in a channel with an oscillating constriction has been studied by the numerical solution of the Navier-Stokes and Euler equations. A vorticity wave is found downstream of the constriction in both viscous and inviscid flow, whether the downstream flow rate is held constant and the upstream flow is pulsatile, or vice versa. Closed eddies are predicted to form between the crests/troughs of the wave and the walls, in the Euler solutions as well as the Navier-Stokes flows, although their structures are different in the two cases.The positions of wave crests and troughs, as determined numerically, are compared with the predictions of a small-amplitude inviscid theory (Pedley &amp; Stephanoff 1985). The theory agrees reasonably with the Euler equation predictions at small amplitude (ε [lsim ] 0.2) as long as the downstream flow rate is held fixed; otherwise a sinusoidal displacement is superimposed on the computed crest positions. At larger amplitude (ε = 0.38) the wave crests move downstream more rapidly than predicted by the theory, because of the rapid growth of the first eddy (‘eddy A’) attached to the downstream end of the constriction. At such larger amplitudes the Navier-Stokes predictions also agree well with the Euler predictions, when the downstream flow rate is held fixed, because the wave generation process is essentially inviscid and the undisturbed vorticity distribution is the same in each case. It is quite different, however, when the upstream flow rate is fixed, as in the experiments of Pedley &amp; Stephanoff, because of differences in the undisturbed vorticity distribution, in the growth rate of the vorticity waves and in the dynamics of eddy A. A further finite-amplitude effect of importance, especially in an inviscid fluid, is the interaction of an eddy with its images in the channel walls.

Geological and geomorphological indicators of former glaciations in the middle Kolyma Basin

Abstract Extensive glaciations developed in the middle Kolyma basin during the Early and Middle Pleistocene. The types of glaciers and their dimensions have been established on the basis of the distribution of glacial and periglacial deposits, the position of glacial troughs and eroded glacial cirques and nivation hollows. The former glaciers developed in low mountainous and hilly terrain.

Effect of border sharpness on the size and position of the focal trough of panoramic x-ray machines

A resolution test pattern was used to determine the size, position, and centers of the focal troughs of four panoramic x-ray machines. The focal troughs were located at slightly different positions for each machine. The center of each focal trough produced varying degrees of sharpness. The average widths of the focal troughs were not greatly different between machines.