Trapezoidal Research Articles

Context-dependent adaptive coding of interaural phase disparity in the auditory cortex of awake macaques.

In the ascending auditory pathway, the context in which a particular stimulus occurs can influence the character of the responses that encode it. Here we demonstrate that the cortical representation of a binaural cue to sound source location is profoundly context-dependent: spike rates elicited by a 0 degrees interaural phase disparity (IPD) were very different when preceded by 90 degrees versus -90 degrees IPD. The changes in firing rate associated with equivalent stimuli occurring in different contexts are comparable to changes in discharge rate that establish cortical tuning to the cue itself. Single-unit responses to trapezoidally modulated IPD stimuli were recorded in the auditory cortices of awake rhesus monkeys. Each trapezoidal stimulus consisted of linear modulations of IPD between two steady-state IPDs differing by 90 degrees. The stimulus set was constructed so that identical IPDs and sweeps through identical IPD ranges recurred as elements of disparate sequences. We routinely observed orderly context-induced shifts in IPD tuning. These shifts reflected an underlying enhancement of the contrast in the discharge rate representation of different IPDs. This process is subserved by sensitivity to stimulus events in the recent past, involving multiple adaptive mechanisms operating on timescales ranging from tens of milliseconds to seconds. These findings suggest that the cortical processing of dynamic acoustic signals is dominated by an adaptive coding strategy that prioritizes the representation of stimulus changes over actual stimulus values. We show how cortical selectivity for motion direction in real space could emerge as a consequence of this general coding principle.

Evaporation Heat Transfer and Pressure Drop Characteristics of Refrigerant R-22 in a P1ate and Shell Heat Exchanger

The evaporation heat transfer coefficient and pressure drop for refrigerant R-22 flowing in the plate and shell heat exchanger were investigated experimentally in this study. Two vertical counterflow channels were farmed in the exchanger by three plates of commercial geometry with a corrugated trapezoid shape of a chevron angel of 45 ° Upflow boiling of refrigerant R-22 in one channel receives heat from the hot downf1ow of water in the other channel. The effects of the mean vapor quality, mass flux, heat flux and pressure of R-22 on the evaporation heat transfer and pressure drop were explored. The quality change of R-22 between the inlet and outlet of the refrigerant channel ranges from 0.03 to 0.05. The present data showed that both the evaporation heat transfer coefficient and pressure drop increase with the vapor quality. At a higher mass flux, the evaporation heat transfer coefficient and pressure drop are higher for the entire range of the vapor quality Raising the imposed wall heat flux was found to slightly improve the heat transfer, while at a higher refrigerant pressure, both the heat transfer and pressure drop are slightly lower.

Experimental Study on R-22 Condensation Heat Transfer Characteristic in Plate and Shell Heat Exchanger

In this study, condensation heat transfer experiments were conducted with plate and shell heat exchangers(P&SHE) using R-22. An experimental refrigerant loop has been established to measure the condensation heat transfer coefficient of R-22 in a vertical P&SHE. Two vertical counter flow channels were formed in the P&SHE by three plates of geometry with a corrugated trapezoid shape of a chevron angle of 45°. Downflow of the condensing R-22 in one channel releases heat to the cold upflow of water in the other channel. The effect of the refrigerant mass flux, average heat flux, system pressure and vapor quality of R-22 on the measured data were explored in detail. The results indicate that at a higher vapor quality the condensation heat transfer coefficients are significantly higher. A rise in the refrigerant mass flux causes an increase in the h(sub)r. Also, a rise in the average heat flux causes an increase in the h(sub)r. Finally, at a higher system pressure the h(sub)r is found to be slightly lower. Correlation is also provided for the measured heat transfer coefficients in terms of the Nusselt number.

Stress Corrosion Crack Rate of STS 304 Stainless Steel in High Temperature Water

Sensitized STS 304 stainless steel crack growth rate(CGR) in high temperature water was investigated under trapezoidal wave loading test using fracture mechanics techniques. The CGR, due to stress corrosion cracking(SCC), were systematically measured as a function of the stress intensity factor and stress. holding time under trapezoidal wave loading. In high temperature water, CGR was enhanced by a synergistic effects in combination with an aggressive environment and mechanical damage. The CGR, was basically described as a summation of the environmentally assisted crack growth rate , and fatigue crack growth rate in air $(da/dN)air,. The CGR, , increased linearly with increasing stress holding time. The CGR, decreased linearly with increasing stress holding time. Fracture surface mode varied from trans-granular cracking to inter-granular cracking with increasing stress holding time.

Creep-Fatigue Crack Growth at CrMo Steel Weld Interface

Creep-fatigue crack growth behavior was experimentally measured particularly when a crack was located in the heat affected region of lCr-5Mo steel. Load hold times of the tests for trapezoidal fatigue waveshapes were varied among 0, 30, 300 and 3,600 seconds. Time-dependent crack growth rates were characterized by the parameter. It was found that the crack growth rates were the highest when the crack path was located along the fine-grained heat affected zone(FGHAZ). Cracks located in other heat affected regions had a tendency to change the crack path eventually to FGHAZ. Creep-fatigue crack growth law of the studied case is suggested in terms of (da/dt) vs. () for residual life assessment.

Distribution of dynorphin A (1-17) in the cat brainstem: an immunocytochemical study.

We have studied the distribution of cell bodies and fibers containing dynorphin A (1-17) in the brainstem of the cat using an indirect immunoperoxidase technique. The highest density of cell bodies was observed in the nucleus of the trapezoid body, whereas a low density of perikarya was found in the inferior and superior colliculi, nucleus of the brachium of the inferior colliculus and in the alaminar and laminar spinal trigeminal nuclei. A moderate density of immunoreactive fibers was found in the nucleus of the solitary tract, dorsal nucleus of the raphe, area postrema, dorsal motor nucleus of the vagus and in the marginal nucleus of the brachium conjunctivum, whereas a low density of fibers was observed in the lateral tegmental field, laminar and alaminar spinal trigeminal nuclei, nucleus of the trapezoid body, nucleus coeruleus, brachium conjunctivum, Kölliker-Fuse nucleus, periaqueductal gray and in the inferior and superior colliculi. The highest density of fibers containing dynorphin A was visualized in the substatia nigra. The widespread distribution of dynorphin A (1-17) immunoreactive structures suggests that the peptide could be involved in respiratory, cardiovascular, nociceptive and auditory mechanisms.

A set of analytic formulas for capacitance of VLSI interconnects of trapezium shape

In VLSI timing analysis, a quick and accurate extraction of interconnect line to line and line to ground capacitance is very important. This paper presents a set of analytic formulas for the capacitance of one, two, and three trapezium interconnect lines over a ground plane which show better than 7% agreement with the capacitance values from the numerical simulation. >

Distribution of Cutting Tool Contact Loads along Rake and Flank Surfaces

Summary The distribution of contact loads along rake and flank surfaces is determined by integration of geometrical and physical parameters of cutting process. The chip formation model has bean proposed as trapezium shape lamellar structure formation process. This model has described chip curves, its contact length and contact loads distribution taking into account both plastic and elastic chip deformation. The contact loads distribution on the flank surface has calculated in connection with contact loads value on rake surface. The obtained results are in a good agreement with experiments.

A generalization of Simpson's Rule

Let\(TA(f) = \int\limits_a^b {\frac{1}{2}(P_a^n (x) + P_b^n (x))dx} \) and let\(TA(f) = \int\limits_a^b {P_{(a + b)/2}^{n + 1} (x)dx} \), where Pcn denoles the Taylor polynomial to f at c of order n, where n is even. TA and TM are reach generalizations of the Trapezoidal rule and the midpoint rule, respectively, and are each exact for all polynomials of degree ≤n+1. We let L(f)=αTM(f)+(1−α)TA(f), where\(\alpha = \frac{{2^{n + 1} (n + 1)}}{{2^{n + 1} (n + 1) + 1}}\), to obtain a numerical integration rule L which is exact for all polynomials of degree≤n+3 (see Theorem 1). The case n=0 is just the classical Simpson's rule. We analyze in some detail the case n=2, where our formulae appear to be new. By replacing P(a+b)2/n+1(x) by the Hermite cubic interpolant at a and b, we obtain some known formulae by a different approach (see [1] and [2]). Finally we discuss some nonlinear numerical integration rules obtained by taking piecewise polynomials of odd degree, each piece being the Taylor polynomial of f at a and b, respectively. Of course all of our formulae can be compounded over subintervals of [a,b].

Saturation deficit tolerance spectra of phytophagous mites and their phytoseiid predators on cassava

Frank M. Bakker, Ma_rtha E. Klein, Nora C. Mesa and Ann R. Braun, 1993. Saturation deficit tolerance spectra of phytophagous mites and their phytoseiid predators on cassava. Exp. Appl. Acarol. 17: 97-113. In South America, phytophagous cassava mite populations reach high densities during the dry season but occur in low numbers during the rainy season. Some of their phytoseiid predators, however, show the reverse pattern. We test the hypothesis that this different seasonal phenology can be attributed to distinct saturation deficit tolerance spectra. Eggs of various species c.q.. strains of phytoseiids, originating from different climate zones, were screened for their tolerance to a range of saturation deficits and compared with the tolerance spectrum of tetranychid species collected from cassava. In total t9 species/strains of predatory mites were compared with six tetranychid species. The response curves for all predators were sigrnoidal with a narrow and specific region of saturation deficits where egg hatch success fell from 100% to 0%. Using probit analysis this region was characterized by the SDs0, the saturation deficit at which only 50% of the eggs hatch. The response curves for the herbivores were trapezoid. In contrast to the phytoseiids the latter do not differ in the range of saturation deficits tolerated, but in the magnitude of the response. It appeared that inter-strain differences in the Phytoseiidae are sometimes larger than interspecific differences. We demonstrate that there is a significant correlation between population-specific SDs0values and long term average relative humidity in the collection site. The implications of this finding are discussed in terms of condition specific competition.

ChemInform Abstract: A Cyclic Methyleneborane with a Trapezoid Geometry.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

An evaluation of retrograde tracing methods for the identification of chemically distinct cochlear efferent neurons.

We have compared retrograde labelling of rat olivocochlear neurons after unilateral cochlear injections of wheatgerm agglutinin conjugated horseradish peroxidase (WGA-HRP) and free HRP. After cochlear injection of WGA-HRP, labelling of nerve cell bodies in the brainstem can be explained not only as conventional retrograde labelling resulting from uptake by efferent nerve terminals synapsing on or near hair cells, but also as spurious labelling originating from tracer leakage, through the periotic duct and over the eighth nerve sheaths, into the cerebral-spinal fluid. Depending on the length of survival time, spurious labelling can involve small portions of the nucleus of the trapezoid body or the entire auditory brainstem and other non-auditory centers. On the contrary, moderate amounts of free HRP delivered to the cochlea do not lead to spurious labelling. With free HRP as the tracer of choice, we found that cochlear efferent cells were located not only in the ipsilateral LSO body and bilaterally within MVPO and RPO as already described by White and Warr, but also surrounding the ipsilateral LSO and in the ipsilateral LVPO. The allocation of these newly described olivocochlear neurons to the medial large cell or lateral small cell system is uncertain because they are located laterally in the brainstem and project ipsilaterally but are large spherical to fusiform or multipolar cells. A zinc salicylate-formol fixative and a metal intensified DAB reaction were found to be effective in visualizing retrogradely transported HRP in neurons and allowed immunocytochemical staining of the same sections with antisera to glutamic acid decarboxylase and choline acetyltransferase. This double label protocol can be used to produce a neurochemical map of the OC systems.

DOUBTS REGARDING VALUE OF TRAPEZOIDAL RELAXING INCISION FOR RELIEF OF ASTIGMATISM

DOUBTS REGARDING VALUE OF TRAPEZOIDAL RELAXING INCISION FOR RELIEF OF ASTIGMATISM

A flexible beamshaper

The number of flashes required to form a pattern with a variable shape electron beam pattern generator can be reduced when more flexible shapes can be generated. This is especially the case when patterns contain oblique or curved elements. A beam shaper is proposed which enables the transformation of a rectangular shaped spot into a trapezium shape, a parallelogram shape, a triangular shape or into a ring segment. The setup time can be as short as in ordinary beam shapers.

Diagnostic Value of Labyrinthine Preponderance

The abnormal responses in 185 cases of aural vertigo examined by the computerized trapezoid rotation test (Contraves), were classified into the following 3 types:1) Labyrinthine preponderance ipsilateralis (LPi) in 66 cases of acute labyrinthosis of the impaired side due to acute labyrinthitis, Meniere's disease, (pre-attack), sudden deafness (recovery stage), etc.2) Labyrinthine preponderance contralateralis (LPc) in 70 cases of chronic labyrinthosis of the impaired side due to labyrinthine trauma, chronic labyrinthitis, Meniere's disease (post-attack), etc.3) Vestibular recruitment (Rec) in 49 cases of fixed labyrinthosis of the impaired side due to labyrinthine trauma, sudden deafness (fixed stage), etc.“Labyrinthine preponderance” was thought to be a very important indicator for follow-up treatment-course of aural vertigo.

Some simple geometry of the welfare loss from competitive monopolies

In the standard neoclassical approach to analyzing monopoly, monopolies are merely assumed to exist. This assumption has never set well with many economists, who argue that there should be competition for monopolies just as there is competition within an industry. The issue has been considered recently within what has come to be known as 'rent-seeking' literature.1 While the rent-seeking literature has many dimensions, one of its central arguments is that the competition for monopolies increases the welfare loss resulting from them.2 The rent-seeking model argues that the welfare loss from monopoly is not only the 'Harberger' triangle; it also includes an amount related to the monopolist's profit and in the special case of 'competitive rent-seeking' the welfare loss from rent-seeking equals the entire monopoly profits. Thus, in the special case of competitive rent-seeking the total welfare loss from monopoly is given by the shaded trapezoid in Figure 1.

Histochemical localization of acetylcholinesterase in the cochlear and superior olivary nuclei. A reappraisal with emphasis on the cochlear granule cell system.

The present account reconsiders the acetylcholinesterase (AChE) staining pattern of the cochlear nuclei with special emphasis on positively stained afferents from the olivocochlear neurons to the cochlear granule cells system. The main part of the study is based on AChE- and silver-stained sections of normal and brainstem-operated cats. AChE-stained sections of normal mouse, cat and chinchilla are used for comparative purposes. The rat superior olive contains three types of AChE-positive neurons probably contributing to the olivocochlear bundle; densely stained large neurons of the periolivary region, densely stained small neurons at the margin of the lateral superior olive (LSO), and weakly stained small neurons within LSO. Largely uncrossed fibers, probably collaterals of the olivocochlear bundle, enter the cochlear nuclei via three routes, defined here as the strial, subpeduncular and ventral routes. Collectively they form a terminal fiber plexus in certain portions of the granule cell domain, but with some fibers branching in the extragranular regions of the nuclear complex as well. The individual fibers end in a fashion resembling cerebellar mossy fibers. The cochlear nuclei in addition contain conspicuous dense patches of precipitate, which, like the AChE-positive fibers, appear after short incubation and are mainly restricted to the granule cell domain. In contrast to the fibers, however, they are resistant to central deafferentation and therefore may represent intrinsic structures of the granule cell system. Moreover, there is a diffuse neuropil precipitate which grows in distribution and density with incubation time. It is present both in granular and extragranular areas of the complex and is partly dependent upon the integrity of the weakly stained trapezoid body. In spite of considerable interspecies variations with regard to the described AChE-positive elements, these are present also in mouse, cat, and chinchilla. The significance of the findings and of the interspecies differences are discussed. A simplified terminology of the superior olivary complex is proposed.

Homothetic coverings of trapezoids

Homothetic coverings of trapezoids

Growth of the nasopharynx and adenoid development from one to eighteeen years.

1. The dimensions of the nasopharynx, the adenoids and the nasopharyngeal airway were analyzed in twelve subjects selected from the longitudinal growth study of the Child Research Council of Denver. 2. The nasopharyngeal area was defined by four skeletally defined lines which formed a trapezoid. The nasopharyngeal area was divided into an adenoid-pharyngeal wall and airway areas which were measured using a polar planimeter. The trapezoid analysis proved to be a useful technique for quantification of nasopharyngeal dimensions. 3. The growth of the nasopharynx from nine months to 18 years was established and reflected the different growth patterns of males and females. 4. The sphenoid line/palatal line angle (theta) and nasopharyngeal depth were established early in life and contributed little to the increase of nasopharyngeal area. The increase in nasopharyngeal area corresponded to the descent of the palate from the sphenoid bone which increased nasopharyngeal height. 5. Restriction of the nasopharyngeal airway frequently occurred during the pre- and early school years due to adenoid hypertrophy which exceeded the usual increase in nasopharyngeal capacity. 6. The nasopharyngeal airway increased during pre- and early adolescence due to the concurrent increase in nasopharyngeal area and adenoid involution. 7. Ten subjects had a history of tonsil and adenoid surgery, but of these only five demonstrated what appeared to be complete removal of nasopharyngeal and adenoid tissue as seen on postsurgical radiographs. The possibility that surgical technique may be the critical factor in the completeness of adenoid removal is presented. 8. The mandibular angle did not apear to be affected by periods of nasopharnygeal airway obstruction is any of the subjects in this study. However, an expanded longitudinal study would be required to determine if restriction of the nasopharyngeal airway influences facial form and occlusion.

Lightness, embeddedness, and contrast.

A rnonocularly observed, upright trapezoid appeared darker than when observed binocularly, but it also appeared slanted under monocular and upright under binocular viewing. When slanted, it may be said to have been more embedded in its background. When embeddedness was then controlled, the lightness difference between monocular and binocular viewing was markedly reduced toward zero. These effects were independent of the location of the illuminating-source. Although the results could be interpreted to mean that one percept influences a second, it should be noted that the cited mean effects were never greater than .11 log ft-L.