Canal Cross-section Research Articles

Method of manufacturing an in-the-ear hearing aid

In a method of manufacturing an in-the-ear hearing aid an auxiliary element, whose cross-section is larger than that of an auditory canal, is introduced into the auditory canal. As a result, the auditory canal is expanded. Subsequently, a hollow vent tube is inserted into the auditory canal, after which the auditory canal is filled with a viscous material. After the viscous material has solidified the mold is removed from the auditory canal. The vent tube insures that air is admitted to a space behind the mold. The mold thus formed has a cross-section larger than the cross-section of the auditory canal. Subsequently, a housing for the hearing aid is made, the mold being used as a template. Consequently, the heating aid will fit tightly in the auditory canal, which improves the wearing convenience. The auxiliary element used in this method has a cylindrical wall formed with a plurality of apertures to allow the passage of the viscous material to spaces between the auxiliary element and the wall of the auditory canal. The auxiliary element further comprises a sleeve for guiding the vent hose.

Sensory organs on the body parts of the bed-bug Cimex hemipterus fabricius (Hemiptera : Cimicidae) and the anatomy of its central nervous system

Anatomy of the sensory organs on the prominent body parts of the adult bed-bug Cimex hemipterus (Hemiptera: Cimicidae) and its central nervous system (CNS) was studied by light, transmission, or scanning electron microscopy. The distal tips of antenna and rostrum were found to have rich complements of sensilla. The antenna has both olfactory and gustatory sensilla. Olfactory sensilla project to the antennal lobe organized in the form of glomeruli, while the 2nd component, presumably from gustatory sensilla, projects to the suboesophageal ganglion. The ultrastructure of the sensory pegs on the rostrum of C. hemipterus does not resemble the chemosensilla of adult insects; rather they resemble the larval sensilla of Drosophila melanogaster in the maxillary organ. Earlier we believed this to be a gustatory organ. A few similar sensilla also occur on the antenna, indicating its multimodal role. Amongst the 3 types of sensory hairs located on legs, there are only a few gustatory hairs (7–10 hairs) on the tibia. The pointed and serrate mechanosensory hair types occur in abundance; the serrate type are prominently present on the lateral surface of the legs. On other parts of the body such as the thorax or abdomen, serrate hairs are most abundant. Both the distal segment of antenna and rostrum are invested by 2 nerves, where the axon counts of the 2 antennal nerves are 380 and 425, while each rostral nerve on average has 205 axons. Abundant clusters of microtubules were found in the brain, thoracio-abdominal ganglia, leg-nerves, and the space between muscles and cuticle. These conspicuous microtubule-clusters occur in interaxonal space, mainly glial cells, in the nervous system. In addition, the glial cells have osmiophilic junctions amongst themselves. A novel “hinge and joint” system, which controls the cross-section of the food canal and the salivary duct in an inversely related manner, was found in the rostrum of the bed-bug.

A computerized method for the evaluation of root canal morphology.

The objective of this research was to develop a technique that would allow three-dimensional imaging of root canals utilizing computer image processing. Ten single-rooted permanent human teeth with mature apices were analysed. The teeth were decoronated and fixed on boards with the long axis of the root perpendicular to the board. The cross-sectioning started at the root apex and continued in the coronal direction, roughly perpendicular to the long axis of the ++root. The samples were divided into two groups. The first five samples were sectioned 15 times, each section being 0.5-mm thick, in order to obtain the three-dimensional reconstruction of the root and the root canal. The root apex of each sample was cross-sectioned 19 times and each section was 0.2-mm thick. After each section, the root canal contour was defined utilizing the calibrated net with coordinate system in the ocular of the stereomicroscope. The coordinates of the root canal cross-section contour thus determined, together with the value of the thickness of each cut, were relevant input data for the reconstruction of the root canal cross-sections, longitudinal sections and for the final three-dimensional rebuild of the root and the root canal model. this technique appears to be highly accurate in determining the anatomy of the root canal system and may also be applied in other fields of dental research.

An evaluation of the potential for infilling existing pipeline canals in Louisiana coastal marshes

The impact of canals and their dredged-material levees on Louisiana coastal marshes has been assessed in a number of studies. The aerial coverage by canals and associated dredged-material levees has been shown to be approximately 10% of total marsh area in coastal Louisiana, which is about the same coverage as natural channels. In addition to the direct loss of marsh habitat caused by the canals, the indirect effects of dredge material placement in levees has been associated with marsh deterioration. The restoration of productive fisheries habitat by infilling pipeline canals depends upon maximizing the area of shallow water in the canals and restoring as much of the adjacent marsh habitat as possible by removing dredged-material levees. The degree to which the canal can be infilled depends upon the amount of dredged material available and the bathymetry of the canal at the time of backfilling. Geomorphic survey and analysis was used to evaluate the potential result of infilling canals and the type of habitat that may result. Comparison of data for saline and brackish canal segments indicates that for both plugged and unplugged canals, canals in brackish areas have greater potential for infilling than those in saline areas. However, older brackish canals have a greater potential for the creation of shallow water habitat than younger canals, suggesting that changes in canal cross-section may be of greater magnitude than changes in levee material. Our analysis demonstrates that simple survey techniques can be used to indicate the potential efficacy of canal infilling. We recommend that such surveys be used to evaluate both pipeline and abandoned location canals across the Louisiana coastal zone to determine the potential for increased shallow water habitat.

Improved 0?1 programming model for optimal flow scheduling in irrigation canals

An improved 0–1 programming model was presented for optimal flow regulation and optimal grouping and sequencing of outlets in irrigation distributaries, under restrictions of both the rotational period and the incoming flow rate into distributaries. The problem was solved using a commercially available 0–1 programming software package. The example computations indicated that this model could effectively provide a constant flow rate into the canal during most of the rotation period, and thus reduce the frequency of headgate operation. This formulation also minimized the accidental water wastage by appropriately sizing the canal cross-section.

Trench formation in group explosions with linear charge distribution

Using the laboratory-modeling method developed at the All-Russian Scientific-Research Institute of Engineering Physics, group explosions for the creation of long trenches (canals) are investigated. The minimum canal cross section and its other dimensions are obtained as a function of the basis parameters of the explosion. Conditions for the creation of canals with minimum fluctuation of the profile over the trench length are found, criteria of economic efficiency are derived, and a method is given for choosing the explosion parameters so as to create a canal of specified cross section with minimum expenditure of explosives. The results of the model experiments are compared with the trench dimensions in the Baggi (USA) and T-II (Russia) nuclear explosions.

Effects of endoscopic release of the transverse carpal ligament on carpal canal volume

Ten hands in 10 patients with carpal tunnel syndrome were treated by subcutaneous transverse carpal ligament release using the Universal Subcutaneous Endoscope system. We analyzed the morphologic changes of the carpal canal with magnetic resonance imaging (0.064 T) before and after the operation. The axial plane, which includes the beak of the trapezium and the hook of the hamate, was selected for analysis. The soft tissue boundaries of the carpal canal were outlined at the plane. The cross-sectional area of the carpal canal was 232 ± 49 mm2 before surgery and 320 ± 108 mm2 after surgery. There was a 33% ± 15% increase of the carpal canal cross-section after transverse carpal ligament release. The transverse carpal ligament became more outwardly convex after the operation. The endoscopic procedure is effective for increasing the cross-sectional area and volume of the carpal canal.

Root canals in one-rooted maxillary second molars.

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth extracted in Denmark. The collection currently contains 104 one-rooted, permanent maxillary second molars. The root complex on these teeth was sectioned at the junction between the coronal and the apical halves, i.e. mid-root, and at the junction between the middle and the apical thirds, i.e. apically. Using a stereomicroscope we then registered, mid-root and apically, the following variables: canal number, canal position, and canal cross-section. Mid-root there was 1 centrally located root canal in 25.96% of the teeth examined; 2 canals were observed either mesially and distofacially, mesiofacially and distally, or facially and lingually in 34.62%; 3 canals positioned mesiofacially, distofacially, and lingually were found in 39.42%. At the same level 63.51% of the canal cross-sections were non-circular, whereas 36.49% of the canals had a circular cross-section image. The non-circular canal cross-sections could more specifically be characterized as C-shaped, Y-shaped, hourglass-shaped or the root canal had a greater faciolingual than mesiodistal extension or, respectively, a greater mesiodistal than faciolingual extension. Apically there was 1 centrally located root canal in 35.58%; 2 canals were observed with a position either mesially and distofacially, mesiofacially and distally, or facially and lingually in 37.49%; 3 canals located mesiofacially, distofacially, and lingually were found in 26.92%. At the apical level, 64.32% of the root canal cross-sections were non-circular, whereas 35.68% of the canals showed a circular cross-section. The results presented here are aimed at: clinical dentists, endodontists, and dental morphologists.

Effect of Submerged Weeds on the design: Procedure of earthen Egyptian canals

It is usual practice, in good conditioned earthen Egyptian canal design, to assume that Manning's roughness coefficient is equal to 0.025. Field monitoring showed that more than 40% of the canals are infested by Submerged Weeds (Potamogeton pectinatus, Potamogeton nodosus andPotamogeton crispus), in which case Manning's n-vlaues are higher than in the design. A numerical procedure for the design of canals with submerged weeds in Egypt is presented. The procedure is based on the Manning formula and the n-vR relationships, vegetation density and different types of distribution of submerged weeds along the canal cross-section. The presented numerical solution is an iteration process within the capabilities of a scientific pocket calculator.

A new method of tooth replantation and autotransplantation: Aluminum oxide ceramic for extraoral retrograde root filling

After an initial clinical test phase, the new method of replantation and transplantation with the use of aluminum oxide ceramic for retrograde root filling may be viewed as possible differential indications to other methods, even to apicectomy in the molar region. Twenty-three of the twenty-five replantations and eight of the nine transplantations may be regarded as having been successful. Contraindications are cases of wide apical foramina and oval or octagonal root canal cross sections.

Estimation of snowdrift filling of sections of earth canals

The practice of operating existing hydraulic engineering complexes the year-round under conditions of a harsh climate has revealed a number of difficulties in delivering water along open earth canals in the winter [1 ]. Snowdrifts in the channel of canals are the cause of some difficulties [2]. They are produced f rom snow being transported by blizzards and form on elements of the canal cross section (slopes, berms, surface of the ice) in different volumes. The parameters of snowdrifts and their role in creating emergency situations on operating cascades depend on the physiographic conditions of the region and design characteristics of the hydraulic structures. The sections of canals and their individual elements (embankments, spoil banks) project as poorly streamlined bodies for a perpendicularly directed snow--wind flow. The wind flow leaves behind them a region of recirculating air, which is closed in this region of the flow. Visual observations of the process of formation of snow deposits in the channel conducted on the Irtysh--Karaganda canal in 1974-1979 indicate a regularity of the deposition of snow within the area of recirculation of the flow (eddy zone). It was established from the results of statistical analysis of the data of field measurements of snowdrift filling of sections of canals that the surface of the snow drifts coincides with the line of the axial component of the zero speed of the snow--wind flow, which regardless of the size and shape of the section runs at an angle of 80 ~ -+ 95" to the vertical at the point of separation of the air flow. The line of zero speeds is the boundary of snow accumulation in the channel. Maximum snowdrift filling of canal sections will be observed when the area of the eddy zone is filled to the line of the zero speeds. The characteristics of the limits of snowdrift filling of canal sections obtained made it possible to develop relations for calculating the main parameters of snow deposits. The formula for calculating the maximum volume of snow in a trapezoidal channel has the form Vsd = H 2 (5,673--cig tp)/2, ( 1 )

Use of polyvinyl chloride liners for large irrigation canals in Alberta

In 1982, the Government of Alberta began a program to rehabilitate and expand existing irrigation headworks systems within southern Alberta. Particular emphasis was placed on effectively minimizing future seepage from these canal systems. To fulfill this requirement, Alberta Environment undertook an extensive study of methods of seepage control that would be most appropriate for use in this program. The study concluded that the installation of a complete canal buried membrane lining was one of the most effective methods for controlling seepage. The geomembrane material selected for use as the buried liner for this installation was 0.5 mm (20 mil) thick polyvinyl chloride (PVC). This paper presents the basis on which the complete canal buried membrane lining system was selected, the reasons for selecting the 0.5 mm (20 mil) thick PVC as the lining material, the quality control program for monitoring the purchasing of the PVC material, and the installation procedures used for placing the membrane within the canal cross section. The design criteria and construction procedures relevant to the earth cover material being placed on the membrane liner are also presented. Key words: irrigation, canals, seepage, lining, geomembrane, performance.

Determination of eardrum reflectance using measurement of phase

At frequencies greater than 8 kHz the acoustic energy reflectance at the eardrum is not well established in living human subjects. This quantity is of interest, though, in high‐frequency audiometry and in network modeling of the middle ear. In this paper a technique for measuring high‐frequency reflectances is discussed that makes use of the phase component of a pressure signal, rather than its amplitude. In a section of ear canal having a constant cross section, or having a constant taper, the maximum rate change of phase with position is simply related to the energy reflectance at the eardrum. Experimentally the phase of the pressure signal is determined at several positions over a 2‐mm distance, centered about an interference minimum. By choosing appropriate sound frequencies the measurements can be confined to a 6‐ or 7‐mm region near the ear canal entrance; this avoids the deep penetration of probe microphones required by other techniques, and avoids the large variations in ear canal cross section that occur close to the eardrum. Preliminary results have been obtained, suggesting an eardrum energy reflectance of about 80% (25‐dB equivalent standing wave ratio) at 15 kHz.

Fossil Hexactinellida

The structure and evolution of the hexactinellid skeleton has been conditioned by: (1) the rectangular form of the spicule (ultimately due to the square cross-section of the axial canal), and (2) the sheet-like form of the choanocyte-membrane, properly the choano-syncytium (Reiswig, 1979) as individual choanocytes with proper nuclei do not exist, which is a continuous syncytial sheet bearing outpocketings (diverticula) that correspond to the choanocyte chambers of other sponge groups. In most species the diverticula are separate, and attached to one another by syncytial filaments, but their arrangement as part of a sheet-like structure is still apparent. In a few species the choanocyte membrane becomes a labyrinth of anastomosing tubes. Accompanying these are the essential absence of mesogloea and the paucity of collagen (spongin), which results in the soft parts being essentially confined to the space occupied by the skeleton. The place of mesogloea is taken by a syncytial network of filaments which also form the dermal and gastral membranes.

Irrigation, Water Allocation Strategies, and the Hohokam Collapse

ABSTRACTThis paper explores potential structural characteristics and archaeological indicators of two models of water allocation that may have been implemented by Hohokam groups in central Arizona. One model, termed “regulated competition.” presumes the existence of institutionalized regulatory mechanisms. The second model, termed “unregulated competition,” presumes no such mechanism. Unregulated competition better explains the occurrence of (1) high densities of canals and archaeological sites in upstream portions of the Salt River Basin that do not contain prime alluvial bottomland, and (2) nonoptimal canal gradients and changes in canal cross sections that allow water to be diverted rapidly from major drainages. A sequence of collapse among irrigation systems in different drainages is developed using the unregulated competition model of water allocation and earlier arguments concerning variations in stream flow between basins. When extended to their logical conclusions, these data imply that sites in t...

Formation of a stable canal channel

1. Deformation of the canal cross section occurs where Fro<Frv. 2. A stable canal section can be obtained by two methods: take cross-sectional shapes and a velocity regime such that the inequality Fro⩾Frv is fulfilled at all points of the wetted perimeter; partially reinforce the canal side slopes in the region where Froi<Frv.

Distances d'arrêt des grands navires en canal Etude de l'extension du canal de Suez : essais sur modèle

The stopping distances of large ships in a canal are a major factor in determining the volume of traffic it can convey. This is the case in particular for the Suez Canal. In carrying out the design studies for the enlargement of this canal, which will make it navigable by 150 to 250 000 dwt tankers, it was necessary to determine the intervals to be left between ships in the convoy. The straightforward extrapolation of present values was considered to be hazardous, and the Suez Canal Authority consequently resorted to model tests, effected in part at SOGREAH's Laboratory, using a ship model operated by a pilot on board. The model represented 160 000 dwt and 260000 dwt tankers, at scales of 1/39 and 1/44 (Figs. 1 and 2). Essentially, the aim of the tests was to define a stopping procedure which would allow steerage-way to be maintained throughout the manoeuvre. This requires the very progressive reduction, by steps, of the speed of rotation of the propellor, with especial care being taken at the helm to ensure that the ship returns to the centre-line of the canal after each partial deceleration. It is possible, in this way, to reduce speed to 8 km/h. Below this speed it is necessary to use, in fairly rapid alternation, engine bursts forward and astern, with wide rudder angles, allowing the ship's speed to be reduced to 4 km/h without her touching the banks. Once this speed has been reached, the way can be checked by all possible means : engine full astern, anchors dropped and running along the bank. The deceleration procedure is represented in diagrammatic form in Figure 4. Apart from the actual procedure, the main parameters which determine the stopping distances are the displacement of the ship, the speed of transit and the cross-section of the canal. Tests were run to determine the influence of these factors for the 160000 and 260 000 dwt ships, fully laden, with various canal cross-sections defined by the cross-section ratio n = S/s and by the width coefficient t = canal width at keel/ship's beam, and with speeds ranging from 9 ta 15 km/h (Fig. 3). The main results are as follows : - the stopping distances, as shown in table 2, reach 3300 m for the 160 000 dwt ship and 4300 m for the 260 000 dwt ship, at 15 km/h, - they are more or less proportional to the linear dimensions of the ships, - they increase with the square of the transit speed (figs. 7 and 8). - they are shorter with "wide" cross-sections (r = 3) than with cross-sections that are deeper and narrower, - cross-section ratios of n = 4.5 to 5 are satisfactory. In determining the regulation intervals to be respected by ships in a convoy, account has to be taken of the distance covered before the pilot realises that the way of the preceding ship has been checked, of the margin of uncertainty in assessing ship speeds, distances, etc.. , with the result that intervals of 25 and 30 minutes respectively were recommended for the two ships considered. With a current from the stern, the stopping manoeuvre can only be effected with tug assistance. The stated intervals could be reduced, with control stations every 2 or 5 km. In general terms, the study highlighted the correlation which exists between the stopping distances required by large ships and the width available on either side of the route to be followed by the ship.

Lumbar Spinal Stenosis

Spinal stenosis due to malalignment and/or hypertrophy of the bony margins of the spinal canal is a recognized cause of cauda equina compression and nerve root entrapment. The plain lumbosacral spine roentgenograms reveal the number of lumbar vertebrae, their alignment, their interpedicular distances, the height of the intervertebral disk spaces and the presence of osteophyte formation. It correlates poorly with encroachment on the spinal canal. The transverse axial tomogram directly demonstrates a cross-section of the spinal canal and will show abnormal areas of bone encroachment usually arising from hypertrophied lamina and articular processes. These narrow the posterior portion of the spinal canal and encroach on the lateral recesses. This examination does not demonstrate soft tissue hypertrophy and the stenosis may be even greater than what is apparent due to the bony encroachment. The myelogram expresses how the narrowed spinal canal affects the dural sac and its contained cauda equina. Not infrequently there is an associated herniated disk.

An isoperimetric problem with a nonlinear side condition for sloshing in a symmetric shallow canal

The eigenfrequencies of the oscillations of an ideal liquid in a symmetric, shallow canal are investigated. The shape of the cross section is determined, for which thenth eigenfrequency becomes as large as possible, when the width and the wetted are length of the canal cross section are prescribed. This variational problem leads to a nonlinear eigenvalue problem for two functions. The problem is solved numerically, and, in addition, upper and lower bounds for the maximal eigenvalues are reported.

Locus of Mammary Gland Infections of Corynebacterium bovis

Corynebacterium bovis was shed in 33.5 and 38% of aseptically drawn milk samples from two university dairy herds. Individual quarters were examined to determine locus of infection. C. bovis was cultured from only 5 of 20 samples drawn by syringe from the teat cistern but was in each of the 20 samples drawn through the streak canal. Counts of C. bovis averaged 23,000 from cross sections of streak canal of about 1mm thickness. Numbers of C. bovis were fewer in Furstenberg's rosette and none was recovered from sections of the teat cistern. C. bovis was microscopically visible in ultra-thin sections of streak canal and appeared closely associated with keratinaceous tissues. Numbers were greater than those enumerated by the broth method. There was no microscopic evidence of damage to streak canal tissue from C. bovis in infected and noninfected tissues after staining with hematoxylin and eosin. Results suggest that C. bovis is not established past Furstenberg's rosette.