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PubMed2006

Flooding flows in city crossroads: experiments and 1-D modelling.

This study focuses on the discharge distribution in an intersection of four channels, similar to a city crossroad. The channels and the intersection are all horizontal. Flow enters through two of the channels, and leaves through the other two. The flow is subcritical everywhere, and flow depths are controlled by vertical weirs at the exits of the outlet channels. The main variables that are measured are the flow rates in the four channels. When the weir heights in the outlet channels are the same, the ratio of flow rates in the outlet channels depends only on the ratio of flow rates in the inlet channels; if the outlet conditions are different, other parameters, such as the total flow rate also become important. The flow has also been simulated numerically using a solution of the 1-D Saint Venant equations, with a simple model to predict flow distribution in the intersection. A comparison with the experimental data shows that this model works well for the limited range of experimental conditions studied here. However, further work is needed on a wider range of conditions, closer to real conditions, before the model can be considered valid for practical applications.

Cities↗

PubMed1989

Measurements of gaze movements while driving.

In this study, gaze movements of drivers driving through an intersection were investigated. Gaze movements of drivers in large vehicles were compared with those in small vehicles. There were both similarities and differences in the visual search behaviors of drivers of large and small vehicles. The two groups were similar in that, when approaching an intersection, drivers made repeated saccadic gaze movements; after entering the intersection, saccadic gaze movements were directed ahead in the direction of turning. Differences arose in the frequency and distribution of gaze movements. The number of gaze movements was significantly greater in drivers of large vehicles. The distribution of gaze movements in driving a large vehicle showed a peak at the point 50 to 60 degrees to the right and left of the median plane of the driver. The distribution of gaze movements of drivers of small vehicles showed no peak across the visual field.

Adult↗

PubMed1993

Drilling the posterior wall of the petrous pyramid: a microneurosurgical anatomical study.

Posterior approaches to the petroclival area requiring extensive drilling of the posterior pyramidal wall have been described in the last 10 years. If hearing is to be preserved, damage to the inner-ear structures must be avoided; however, the fine points of this pyramidal drilling technique have never been reported in detail. A microneurosurgical anatomical study was undertaken in 15 cadavers to determine the relationships between bone landmarks and labyrinthine structures that could be used to give some practical drilling guidelines. Drilling of the posterior pyramidal wall is facilitated on identification of the intersection of the petrous ridge with the most anterior portion of the bone ledge covering the sigmoid sinus (petrosigmoid intersection), the bony operculum of the endolymphatic sac, and the petrous ridge. Drilling may proceed rather safely at a minimum depth of 2.5 mm in an area 0.9 cm anterior and 1 cm inferior to the petrosigmoid intersection and petrous ridge, respectively. From there, identification of the vestibular aqueduct, genu, and horizontal portion is necessary to safely open the posterior wall of the internal auditory canal. The vestibular aqueduct represents the lateral and superior limits of drilling. The bone between these areas may then be safely drilled to a depth of at least 2.5 mm. A microneurosurgical dissection of the posterior pyramidal wall conducted in cadaveric material according to these guidelines did not violate any inner-ear structures.

Ear, Middle↗

PubMedDate not supplied

[Choice of optimal centering points of radiation beams in planning radiotherapy in malignant tumors].

A programmed complex has been developed to determine the optimum radiation protocols which include the optimum positions of intersection centers of central axes of radiation beams, the optimum directions of radiation, the optimum time of exposure. Analyzing the optimum radiation protocols has shown that variations in the positions of intersection centers of radiation beams play a crucial role in the targeted formation of the optimum dose fields. To choose the optimum radiation protocols for central lung cancer is a challenge whose solution depends on the initial position of intersection centers of radiation beams, which give rise to iterative solution of emergency problems. An effective radiation protocol has been chosen among its varieties by making a multicriteria assessment of gross characteristics of dose fields in the lung tissue.

Algorithms↗

PubMedDate not supplied

Multiple reproducibility indices for evaluation of cognitive functional MR imaging paradigms.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate a variety of reproducibility indices for cognitive functional MR imaging (fMRI) paradigms that account for both overlapping and extraneous regions of activation. METHODS: Eight right-handed volunteers were imaged with fMRI by using a word-generation paradigm and a forward-backward text-listening paradigm. The paradigms were performed twice in the session and repeated 1 week later. Reproducibility indices for the four repeated studies were determined on the basis of pair-wise computation of the ratio of the probability-weighted intersection volume divided by the union volume of surviving activation clusters. The intersection volume was determined by using several iterations of the morphologic dilatation operator with additional voxels accrued in the intersection weighted by an exponential function. Computed indices included global reproducibility, language area reproducibility, extraneous activation reproducibility, and laterality. RESULTS: The word-generation paradigm had reproducibility values that were significantly greater than those of the forward-backward text-listening paradigm (global reproducibility, 0.75 vs 0.5, P <.005; language area reproducibility, 0.85 vs 0.6, P <.008; mean extraneous activation reproducibility, 0.68 vs 0.41, P <.002). The forward-backward text-listening paradigm demonstrated more focal activations, whereas the word-generation demonstrated larger activations outside the dominant language areas that were highly reproducible. CONCLUSION: For clinically relevant language paradigms, multiple reproducibility indices should be taken into account in selecting an appropriate paradigm. Compared with a forward-backward text-listening task, a word-generation task has higher reproducibility indices at the expense of localizing ability. The forward-backward paradigm demonstrates more focal activations with less extraneous activation.

Adult↗

PubMed2002

Using the metaschema to audit UMLS classification errors.

The Unified Medical Language System integrates about 800,000 concepts from 99 biomedical terminologies. Each concept is assigned to at least one semantic type of the Semantic Network. During the integration, it is unavoidable that some classification errors and inconsistencies will be introduced. In this paper, we present an auditing technique to find such errors and inconsistencies. Our technique is based on an expert reviewing the pure intersections of meta-semantic types of the metaschema, a compact abstract view of the Semantic Network. Results regarding the pure intersections are reported. The analysis results for pure intersections with 1 to 6 concepts are presented. Various kinds of errors are identified.

Semantics↗

PubMed2004

[Verification of maxillary and mandibular asymmetry via orthopantogram's analysis].

AIM: The purpose of this study was to analyse the homologous variables' symmetry (horizontal, vertical, angular and of area surface) of the right and left segment in the maxilla and in the mandible of subjects with a normal occlusion and a malocclusion. METHODS: Two-hundred and two orthopantomograms were analysed (162 with malocclusion, 40 with normal occlusion). These points of reference were used: orbital, condilion, gonion, menton, point A (intersection point between the vertical line passing through the centre of the nasal septum and the horizontal line which links the 2 points O), point B (intersection point between the mandibular margin and the vertical line passing through point O) and point T (intersection point of A-Cn on the maxillary tuberosity). RESULTS: This study did not confirm any statistically significant differences between the right and left analysed variables studied in both groups. CONCLUSION: Orthopantomography may be a useful test in the screening for facial asymmetry.

Adult↗

PubMed2005

[Opening-wedge osteotomy of the proximal tibia].

PURPOSE OF THE STUDY: The aim of this study was to evaluate the accuracy of correction and short-term outcomes of treatment by opening-wedge tibial osteotomy with the use of allograft and a modified Puddu plate fixation. MATERIAL: Between February 2001 and March 2003, 33 operations on 30 patients, at an average age of 54 years, with gonarthrosis and varus deformity were evaluated. Grade III arthritis was diagnosed in 24 knees (73 %) and grade II in nine knees (27 %). METHODS: The preoperative planning as well as intraoperative correction were based on the limb mechanical axis, as shown on an X-ray image of the whole lower extemity. Tibial osteotomy was performed from the medial approach and the position was fixed, in contrast to the original method, with an allograft and a T-plate. The corrrection was planned so that the mechanical limb axis should intersect the articular space at 62 % of its length laterally. The limb was postoperatively immobilized for 4 weeks in a knee brace allowing walking. Limited weight bearing was recommended from the third week. The outcome of treatment was evaluated at 11 months of follow-up by the Lysholm scoring system. RESULTS: Correction of the limb mechanical axis involved the axis intersecting the plane of the joint space on average at 60.2 % of its length, as against the planned 62 %; the average deviation from the planned correction was 2.1 degrees. Lysholm scores improved on average by 23 points. Improvement by 20 points was regarded as a good outcome and was achieved in 31 joints (94 %). Two joints (6 %) showed poor outcomes due to associated complications. The complications included a fissure of the lateral tibial plateau in one knee, failed stabilization with subsequent loss of correction and pseudoarthrosis development in one joint, prolonged healing with a partial loss of correction (5 degrees) in one patient, and superficial infection in one patient. DISCUSSION: In patients with knee arthritis and varus deformity, the achievement of optimal correction of the mechanical limb axis is the prerequisite for a long-term good outcome. Optimal correction, as characterized by Puddu, is attained when the mechanical axis intersects the joint space at 62 % of its length laterally. Hernigou et al. define the hip-knee-ankle angle in the range of 183 degrees -186 degrees as an optimal postoperation correction. In our experience, osteotomy combined with our modification of fixation is an exact method for correcting the axis; in addition, it is simple and is associated with a low occurrence of postoperative complications. In view of a possible total knee arthroplasty, there is less disturbance in the tibial plateau-diaphysis alignment and the tibial tuberosity level is preserved. CONCLUSIONS: Opening-wedge tibial osteotomy with the use of a Puddu plate and allograft in our modification is an effective, exact and simple method of correcting the lower extremity axis, and is associated with few complications. We do not recommend this method for interventions planned to achive corrections of more than 16 degrees, because these have a higher occurrence of complications. The use of allograft seems to have good prospects; another option for achieving large correction includes application of an LCP plate.

Adult↗

PubMed2006

[Determining the relationship between coronary artery and coronary sinus and its tributaries using multislice computed tomography].

OBJECTIVE: To obtain the coronary artery and coronary sinus (CS) and its tributaries imaging with multislice computed tomography (MSCT), measure the distance between coronary artery and CS and its tributaries and analyze their spatial relationships. METHODS: The MSCT scans of 117 patients (67 men, 50 women, age 56 +/- 10 years) were obtained, 3D image reconstructed and the vessels courses evaluated. The concomitant distances and spatial relationships of the vessels were determined. RESULTS: Right coronary artery domination was found in 107 cases (91.4%), left coronary artery domination in 7 cases (6.0%), and co-domination in 3 cases (2.6%). Left circumflex artery (LCX) was concomitant with CS or the great cardiac vein (GCV) in 81 cases (69.2%), intersected with left posterior vein in 62 cases (53.0%) and with middle cardiac vein (MCV) in 5 cases (4.3%), respectively. The dominant coronary artery branched out into the posterior descending artery (PDA) and the left posterior artery (LPA) in 112 cases (95.7%). PDA was concomitant with MCV in 93 cases (79.5%) and intersected with MCV in 44 cases (37.6%). LPA was intersected with MCV in 106 cases (90.6%), and concomitant with CS in 50 cases (42.7%). CONCLUSIONS: MSCT is a reliable tool to visualize the relationship between coronary artery and CS and its tributaries. Owing to the multiple possibilities inherent to this technique, MSCT has broad potential for more clinical use.

Adult↗

PubMed1991

Developmental regulation of asparagine-linked oligosaccharide synthesis in Dictyostelium discoideum.

In the preceding report we demonstrated that the expression of two developmentally regulated alpha-mannosidase activities is induced in Dictyostelium discoideum during its differentiation from single-cell amoebae to multicellular organism (Sharkey, D. J., and Kornfeld, R. (1991) J. Biol. Chem. 266, 18477-18484). These activities, designated membrane alpha-mannosidase I (MI) and membrane alpha-mannosidase II (MII), were shown to have several properties in common with rat liver Golgi alpha-mannosidases I and II, respectively, suggesting that MI and MII may play a role in the processing of asparagine-linked oligosaccharides in developing D. discoideum. In this study we analyzed the structures of the asparagine-linked oligosaccharides synthesized by D. discoideum at various stages of development to determine the timing and extent of asparagine-linked oligosaccharide processing. Cells were labeled with [2-3H] mannose, and then total cellular glycoproteins were digested with Pronase to generate glycopeptides that were fractionated on concanavalin A-Sepharose. Glycopeptides from each fraction were digested with endoglycosidase H, both before and after desulfation by solvolysis, and the released, neutral oligosaccharides were sized by high pressure liquid chromatography. At early stages of development, D. discoideum contain predominantly large high mannose-type oligosaccharides (Man9GlcNAc and Man8GlcNAc). Some of these are modified by GlcNAc residues attached beta 1-4 to the mannose-linked alpha 1-6 to the beta-linked core mannose (the "intersecting" position), as well as by fucose, sulfate, and phosphate. In contrast, the oligosaccharides found at late stages of development (18-24 h) have an array of sizes from Man9GlcNAc to Man3GlcNAc. These are still modified by GlcNAc, fucose, sulfate, and phosphate, but the percent of larger high mannose oligosaccharides that are modified with GlcNAc in the intersecting position decreases after 6 h of development, in parallel with the decrease in the intersecting GlcNAc transferase activity. Similarly, the changes in the size of asparagine-linked oligosaccharides synthesized during development correlate well with the appearance of MI and MII activities and suggest that these developmentally regulated alpha-mannosidase activities function in the processing of these oligosaccharides. This is supported further by the observation that oligosaccharide processing was inhibited in late stage cells labeled in the presence of either deoxymannojirimycin, an inhibitor of MI, or swainsonine, an inhibitor of MII.

Animals↗

PubMed1989

Feasibility test of a new method to measure retinal thickness noninvasively.

There are many devastating ocular diseases that are directly related to an alteration of the retinal or nerve fiber layer thickness, such as glaucoma and macular edema. To diagnose these diseases earlier and to monitor their therapy more sensitively, an accurate measurement of the tissue thickness is needed. Since no clinical method is currently available, we developed and tested a new method capable of measuring noninvasively the retinal thickness. The separation between the images of the anterior and posterior intersections is quantitated by an optoelectronic system. The theoretical performance of the method has been calculated. Tests of the method in a model eye indicated that the measurements were basically diffraction limited, their reproductivity was +/- 9 microns, and their accuracy was 5.5 microns. Tests performed in vivo indicated that two intersections between the laser and the retina are present and correspond to the anterior and posterior surfaces of the retina. These intersections can be resolved and analyzed to yield quantitative data. These encouraging results indicate that this method is feasible and could yield sensitive measurements of the retinal thickness.

Calibration↗

PubMed1988

A geometric model for estimating villous surface area in rat small bowel is justified by unbiased estimates obtained using vertical sections.

Sampling schemes developed for use with a geometric model of rat small bowel are tested against a design-based scheme (vertical sectioning with cycloid test lines) which offers unbiased estimates of surface amplifications due to villi. The model-based methods comprise transverse and longitudinal sectioning coupled with putative correction factors. Comparisons are based on proximal, middle and distal segments of six small bowels. Transverse and longitudinal sections through the same segments of each animal were analysed by conventional intersection counting (using straight test lines). Appropriate intersection ratios were multiplied by their respective correction factors in order to calculate surface amplifications. Longitudinal sections were employed further as vertical sections and intersections were counted with cycloid arcs to obtain unbiased estimates of surface amplifications. Both model-based schemes (transverse and longitudinal) gave group mean values similar to those obtained by vertical sectioning. Therefore, the use of a geometric model in past studies on rat small bowel can now be justified on grounds of negligible bias.

Animals↗

PubMed1983

Freeze fracture morphology of the tight junctions of the eccrine sweat gland from patients with cystic fibrosis.

The resorption of Na+ and Cl- across the duct of the human eccrine sweat gland is markedly decreased in individuals with cystic fibrosis (CF). Conceivably, a defective transcellular ion transport mechanism or an increased paracellular backflux of ions could account for the abnormal salt resorption in the sweat gland duct and other organs affected in CF. Tight junctions are thought to regulate paracellular ion flow. Specifically, the number of junctional elements observed by freeze fracture are believed to correspond with the extent of paracellular transport. We compared the freeze fracture morphology of tight junctions of eccrine sweat glands taken from 11 control and seven CF patients. In an attempt to "fingerprint" the junctions morphometrically, the following parameters were measured: the number of strands, the depth of the junction from the apical to the basal strand, the angle of intersection between strands, and the mean distance along a strand between intersections with two other strands. No significant difference was observed between control and CF sweat glands in the freeze fracture morphology of the tight junctions of the duct, the segment where the net reabsorption of Na+ and Cl- is abnormally decreased in CF. Significant changes were observed, however, in the means of the number of strands, the depth, and the distance between intersections for the tight junctions of the intercellular canaliculus of the secretory coil, which appears to function normally in CF.

Adolescent↗

PubMed1982

Preferential localization of polyribosomes under the base of dendritic spines in granule cells of the dentate gyrus.

Electron microscopic studies of the dentate gyrus of the rat have revealed an apparent association between polyribosomes and dendritic spines. The present study was designed to elucidate the nature of this association. Our qualitative observations revealed that polyribosomes appeared primarily in two locations within the dendrite: (1) beneath the base of identified spines just subjacent to the intersection of the spine neck with the main dendritic shaft and (2) beneath mounds in the dendritic membrane which had the appearance of the base of a spine which extended out of the plane of section. To quantitatively define the nature of the apparent association, we attempted to determine (1) the proportion of spines with associated polyribosomes and (2) the proportion of the polyribosomes within dendrites which are associated with spine bases. Evaluation of profiles which were identifiable as spine neck-dendritic shaft intersections in a single section revealed that an average of 12.2% had associated polyribosomes. A serial section analysis revealed a somewhat higher incidence, however. Of a collection of 34 through-sectioned spines, 29% had polyribosomes which were revealed in one or more of the sections comprising the series. To evaluate what proportion of polyribosomes within the dendrite was associated with spines, we evaluated a series of photographs covering approximately 1250 micrometer2 of the dentate molecular layer from five animals, identifying all polyribosomes within dendrites and scoring their location as being (1) under spines, (2) under mounds, or (3) other. An average of 9.6% of the polyribosomes were found under processes identifiable as spine neck-dendritic shaft intersections, while 71.4% of the polyribosomes were found under mounds. Only 19% were not obviously associated with spines or mounds. Spine bases and mounds comprise only 3 of 35%, respectively, of the outline of dendritic profiles, however, indicating that the high incidence of polyribosomes under these elements cannot be accounted for by chance. To attempt to determine whether the mounds represent the base of dendritic spines, 68 mounds in 21 dentritic profiles were selected from the middle of the series of 20 serial sections. Ninetine of these mounds (28%) were continuous with an identified spine, and an additional 31% were continuous with thin processes of the size and appearance of spine necks. Thus, most of the mounds probably do represent the base of spines which extend out of the plane of a single section.

Animals↗

PubMed1981

pH-dependence of catalytic constants of the enzyme reaction--some remarks.

The influence of the hydrogen ion concentration on catalytic constants (kcat, KM and kcat/KM) was investigated under steady-state conditions where all steps of the Scheme, are taken into the consideration. The relative value of the rate constants has an influence on pH dependence of catalytic constants. The pH of intersection points of the tangents at the portion of functions pKM, Ig kcat, lg kcat/KM = f(pH) with different slopes are the values of true pKa of catalytically important ionizable groups in the free enzyme or in the enzyme-substrate complex(es), when the conditions k'-1, k'1, k'2 = 0 are valid. If e.g. k'-1, k'1 not equal to 0 the pH of the intersection points of the tangents is sometimes not the true value of the pKa. In this connection it is possible that more than one intersection point exists (in the plot lg kcat, pKM or lg kcat/KM versus pH) when only one ionizing group in the active site of an enzyme is present.

Catalysis↗

PubMed1995

MR volume estimation of subcortical brain lesions and ventricular cerebrospinal fluid: a simple and accurate stereologic method.

PURPOSE: To describe an MR imaging quantification method for estimation of total volumes of both white and gray matter subcortical lesions and ventricular cerebrospinal fluid (CSF) in the living human brain, and to determine the method's reliability. METHODS: In 12 subjects, total subcortical lesion and ventricular CSF volumes were estimated using systematic sampling. Systematic sampling was performed on equidistant MR sections using a counting grid with systematically ordered intersection points. The grid was randomly positioned on each consecutive MR section. Each grid intersection point hitting the structure of interest represents a fixed known volume dependent on grid intersection point distance and the sum of the section thickness and section gap. RESULTS: Total volume estimation of subcortical lesion and ventricular CSF takes 15 and 5 minutes per subject, respectively. Coefficients of error of the individual volume estimates ranged from .01 to .13 and are negligible to the coefficients of the group mean (range, .70 to .89). For subcortical lesion volume, the random intraobserver error yielded .04 and for ventricular CSF .02; the random interobserver error amounted to .11 and .04, respectively; and the systematic interobserver error was .15 and .04, respectively. CONCLUSION: The method described here for subcortical lesion and ventricular CSF volume estimation is accurate, reliable, valid, and fast.

Brain↗

PubMed1994

[The surface anatomic observation of cerebral porecentral and postcentral gyrus for scalp acupuncture].

10 heads of adult cadaver were used for investigation of the motor and sensory area of scalp acupuncture. The results are as follows: both the surface anatomy of precentral and postcentral gyrus were not exactly match with the motor and sensory area described in acupuncture textbook respectively. They were backward. Among them, the upper points were 0.5cm backward to motor area and 1.0cm to sensory area, the lower point of precentral gyrus was 1.0cm posterior to the intersecting point of the eyebrow--occiput line and the anterior border of the natural line of the hair at the temple, while the lower point of postcentral gyrus is 2.4cm posterior to the intersecting point above described. Therefore, the authors suggested that the motor and sensory area of the scalp acupuncture should be backward and recommended: take the point 1.0cm and 3.0cm posterior to the midpoint of anteroposterior midline as the upper point of motor and sensory area respectively, 1.0cm and 2.0cm posterior to the intersecting point above described as the lower point respectively. In this way, the motor and sensory areas are better matched with precentral and posrcentral gyrus than before (P < 0.05).

Acupuncture Points↗

PubMed1994

Melatonin-induced decrease of the size of thyrocyte nuclei in rat thyroids incubated in vitro.

The mean volume, intersection area and perimeter of thyrocyte nuclei in rat thyroid lobes incubated with melatonin (Mel), thyrotropin (TSH) or with both substances together, were investigated. The measurements were carried out using a computer system for karyometric examination. Melatonin in concentrations of 10(-8) M, 10(-10) M and 10(-12) M significantly decreased the mean nuclear volume and intersection area of thyrocytes (p < 0.01); the mean perimeter of thyrocyte nuclei was significantly decreased by melatonin in concentrations of 10(-10) M and 10(-12) M (p < 0.01). TSH (20 mIU/ml), when applied alone, significantly decreased the mean volume, intersection area and perimeter of thyrocyte nuclei (p < 0.01). TSH generally did not counteract the melatonin-induced decrease of thyrocyte nuclei except for 10(-10) M melatonin concentration when TSH increased the mean nuclear perimeter (p < 0.01) and slightly enlarged the mean volume (p < 0.05), compared with Mel alone. The results suggest an inhibitory influence of melatonin on thyroid follicular cell activity, and are in compliance with earlier observations.

Animals↗