An extremal property of the mean width of the simplex

1998 ◽  
Vol 310 (4) ◽  
pp. 685-693 ◽  
Author(s):  
Franck Barthe
Keyword(s):  
Extremal Property ◽  
Mean Width ◽  
The Mean

scholarly journals Ethnic variation in medial orbital wall anatomy and its implications for decompression surgery

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Minhui Amy Chan ◽  
Farah Ibrahim ◽  
Arjunan Kumaran ◽  
Kailing Yong ◽  
Anita Sook Yee Chan ◽  
...  
Keyword(s):  
Relative Position ◽  
Ethmoid Sinus ◽  
Decompression Surgery ◽  
Ethnic Variation ◽  
Sinus Wall ◽  
Orbital Wall ◽  
Mean Width ◽  
Significant Difference ◽  
The Mean ◽  
Medial Orbital Wall

Abstract Background To describe the inter-ethnic variation in medial orbital wall anatomy between Chinese, Malay, Indian and Caucasian subjects. Methods Single-centre, retrospective, Computed Tomography (CT)-based observational study. 20 subjects of each ethnicity, were matched for gender and laterality. We excluded subjects younger than 16 years and those with orbital pathology. OsiriX version 8.5.1 (Pixmeo., Switzerland) and DICOM image viewing software CARESTREAM Vue PACS (Carestream Health Inc., USA) were used to measure the ethmoidal sinus length, width and volume, medial orbital wall and floor angle and the relative position of the posterior ethmoid sinus to the posterior maxillary wall. Statistical analyses were performed using Statistical Package for Social Sciences version 25.0 (IBM, USA). Results There were 12 males (60 %) in each group, with no significant difference in age (p = 0.334–0.994). The mean ethmoid sinus length in Chinese, Malay, Indian and Caucasian subjects, using the Chinese as reference, were 37.2, 36.9, 38.0 and 37.4mm, the mean width was 11.6, 10.5, 11.4 and 10.0mm (p = 0.020) and the mean ethmoid sinus volume were 3362, 3652, 3349 and 3898mm3 respectively. The mean medial orbital wall and floor angle was 135.0, 131.4, 131.0 and 136.8 degrees and the mean relative position of posterior ethmoid sinus to posterior maxillary wall were − 2.0, -0.2, -1.5 and 1.6mm (p = 0.003) respectively. Conclusions No inter-ethnic variation was found in decompressible ethmoid sinus volume. Caucasians had their posterior maxillary sinus wall anterior to their posterior ethmoidal walls unlike the Chinese, Malay and Indians. Awareness of ethnic variation is essential for safe orbital decompression.

Cervical and High Thoracic Ligamentum Flavum Frequently Fails to Fuse in the Midline

2003 ◽  
Vol 99 (6) ◽  
pp. 1387-1390 ◽  
Author(s):  
Philipp Lirk ◽  
Christian Kolbitsch ◽  
Guenther Putz ◽  
Joshua Colvin ◽  
Hans Peter Colvin ◽  
...  
Keyword(s):  
Ligamentum Flavum ◽  
Epidural Needle ◽  
Complete Fusion ◽  
Thoracic Epidural ◽  
Loss Of Resistance ◽  
Ligamenta Flava ◽  
Mean Width ◽  
Human Cadavers ◽  
The Mean ◽  
High Thoracic Epidural

Background Cervical and high thoracic epidural anesthesia and analgesia have gained increasing importance in the treatment of painful conditions and as components of anesthetics for cardiac and breast surgery. In contrast to the hanging-drop technique, the loss-of-resistance technique is thought to rely on the penetration of the ligamentum flavum. However, the exact morphology of the ligamentum flavum at different vertebral levels remains controversial. Therefore, the aim of this study was to investigate the incidence and morphology of cervical and high thoracic ligamentum flavum mid-line gaps in embalmed cadavers. Methods Vertebral column specimens were obtained from 52 human cadavers. On each dissected level, ligamentum flavum mid-line gaps were recorded and evaluated with respect to shape and size. Results The following variations were encountered: complete fusion in the mid-line, mid-line fusion with a gap in the caudal part, mid-line gap, and mid-line gap with widened caudal end. The incidence of mid-line gaps at the following levels was: C3-C4: 66%, C4-C5: 58%, C5-C6: 74%, C6-C7: 64%, C7-T1: 51%, Th1-Th2: 21%, Th2-Th3: 11%, Th3-Th4: 4%, Th4-Th5: 2%, and Th5-Th6: 2%. The mean width of mid-line gaps was 1.0 +/- 0.3 mm. Conclusions In conclusion, the present study shows that gaps in the ligamenta flava are frequent at cervical and high thoracic levels but become rare at the T3/T4 level and below, such that one cannot always rely on the ligamentum flavum as a perceptible barrier to epidural needle placement at these levels.

scholarly journals Radiographic Measurement of Cochlear in Sudanese Population using High Resolution Computed Tomography (HRCT)

2021 ◽  
Vol 29 (2) ◽  
Author(s):  
Lubna Bushara ◽  
Mohamed Yousef ◽  
Ikhlas Abdelaziz ◽  
Mogahid Zidan ◽  
Dalia Bilal ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Hearing Loss ◽  
High Resolution ◽  
Temporal Bone ◽  
Healthy Subjects ◽  
Cochlear Nerve ◽  
High Resolution Computed Tomography ◽  
Mean Width ◽  
The Mean ◽  
The Right

This study aimed to determine the measurements of the cochlea among healthy subjects and hearing deafness subjects using a High Resolution Computed Tomography (HRCT). A total of 230 temporal bone HRCT cases were retrospectively investigated in the period spanning from 2011 to 2015. Three 64-slice units were used to examine patients with clinical complaints of hearing loss conditions at three Radiology departments in Khartoum, Sudan. For the control group (A) healthy subjects, the mean width of the right and left cochlear were 5.61±0.40 mm and 5.56±0.58 mm, the height were 3.56±0.36 mm and 3.54±0.36 mm, the basal turn width were 1.87±0.19 mm and 1.88 ±0.18 mm, the width of the cochlear nerve canal were 2.02±1.23 and 1.93±0.20, cochlear nerve density was 279.41±159.02 and 306.84±336.9 HU respectively. However, for the experimental group (B), the mean width of the right and left cochlear width were 5.38±0.46 mm and 5.34±0.30 mm, the height were 3.53±0.25 mm and 3.49±0.28mm, the basal turn width were 1.76±0.13 mm, and 1.79±0.13 mm, the width of the cochlear nerve canal were 1.75±0.18mm and 1.73±0.18mm, and cochlear nerve density were 232.84±316.82 and 196.58±230.05 HU, respectively. The study found there was a significant difference in cochlea’s measurement between the two groups with a p-value < 0.05. This study had established baseline measurements for the cochlear for the healthy Sudanese population. Furthermore, it found that HRCT of the temporal bone was the best for investigation of the cochlear and could provide a guide for the clinicians to manage congenital hearing loss.

scholarly journals The Micro-Geometry Evaluation on Steel Sheets after Chemical Surface Treatment

2013 ◽  
Vol 10 (2) ◽  
pp. 22-25
Author(s):  
Dagmar Draganovská ◽  
Miroslav Tomáš ◽  
Peter Ižol
Keyword(s):  
Surface Treatment ◽  
Steel Sheet ◽  
Unit Length ◽  
Mean Deviation ◽  
Maximum Height ◽  
Chemical Surface ◽  
Steel Sheets ◽  
Mean Width ◽  
The Mean ◽  
Metal Materials

Abstract The protection of metal materials by coatings is one of the most important way to protect the surface against corrosion. Galvanisation of metal surfaces by an electric current is one of the most frequent way of surface treatment due to its wide application. The paper is oriented to the evaluation of the surface quality in terms of micro-geometry. The basic surface of the steel sheet S235JRG2 has been evaluted and compared to the degreased one, galvanized one and surface after galvanizing, chromatizing and phosphating. The microgeometry parameters such as the arithmetical mean deviation Ra, the maximum height of profile Rz, the total height of profile Rt as well as the the mean width of the profile elements RSm and the number of peaks per unit length RPc has been compared.

Processing of form and motion in area 21a of cat visual cortex

1993 ◽  
Vol 10 (1) ◽  
pp. 93-115 ◽  
Author(s):  
B. Dreher ◽  
A. Michalski ◽  
R. H. T. Ho ◽  
C. W. F. Lee ◽  
W. Burke
Keyword(s):  
Spatial Organization ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Orientation Tuning ◽  
Area 17 ◽  
Horizontal Strip ◽  
Tuning Curves ◽  
Mean Width ◽  
Area 21A ◽  
The Mean

AbstractExtracellular recordings from single neurons have been made from presumed area 21a of the cerebral cortex of the cat, anesthetized with N2O/O2/sodium pentobarbitone mixture. Area 21a contains mainly a representation of a central horizontal strip of contralateral visual field about 5 deg above and below the horizontal meridian.Excitatory discharge fields of area 21a neurons were substantially (or slightly but significantly) larger than those of neurons at corresponding eccentricities in areas 17, 19, or 18, respectively. About 95% of area 21a neurons could be activated through either eye and the input from the ipsilateral eye was commonly dominant. Over 90% and less than 10% of neurons had, respectively, C-type and S-type receptive-field organization. Virtually all neurons were orientation-selective and the mean width at half-height of the orientation tuning curves at 52.9 deg was not significantly different from that of neurons in areas 17 and 18. About 30% of area 21a neurons had preferred orientations within 15 deg of the vertical.The mean direction-selectivity index (32.8%) of area 21a neurons was substantially lower than the indices for neurons in areas 17 or 18. Only a few neurons exhibited moderately strong end-zone inhibition. Area 21a neurons responded poorly to fast-moving stimuli and the mean preferred velocity at about 12.5 deg/s was not significantly different from that for area 17 neurons.Selective pressure block of Y fibers in contralateral optic nerve resulted in a small but significant reduction in the preferred velocities of neurons activated via the Y-blocked eye. By contrast, removal of the Y input did not produce significant changes in the spatial organization of receptive fields (S or C type), the size of the discharge fields, the width of orientation tuning curves, or direction-selectivity indices.Our results are consistent with the idea that area 21a receives its principal excitatory input from area 17 and is involved mainly in form rather than motion analysis.

scholarly journals Sexual Dimorphism in Laryngeal Volumetric Measurements Using Magnetic Resonance Imaging

2019 ◽  
Vol 99 (2) ◽  
pp. 132-136 ◽  
Author(s):  
Abdul-Latif Hamdan ◽  
Elie Khalifee ◽  
Georges Ziade ◽  
Sahar Semaan
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Statistical Significance ◽  
Resonance Imaging ◽  
Men And Women ◽  
Mean Width ◽  
Significant Difference ◽  
The Mean ◽  
The Right ◽  
Volumetric Measurements

The objective of this study is to investigate the dimensional and volumetric measurements in the thyroarytenoid (TA) muscle in men and women using magnetic resonance imaging (MRI). The hypothesis is that there is a gender-related difference in these measurements. A retrospective chart review of 76 patients who underwent MRI of the neck at the American University of Beirut Medical Center was conducted. The dimension and volume of the right and left TA muscle were measured on axial and coronal planes short tau inversion recovery images. Male and female groups were compared with respect to demographic data and MRI findings using parametric and nonparametric tests. The mean length of the thyro-arytenoid muscle in males was larger than that in females on the right (males 2.44 [0.29] cm vs females 1.70 [0.22] cm) and on the left (males 2.50 [0.28] cm vs females 1.72 [0.24] cm) reaching statistical significance ( P < .001). The mean width of the thyro-arytenoid muscle in males was larger than that in females on the right (males 0.68 [0.13] cm vs females 0.59 [0.11] cm) and on the left (males 0.68 [0.12] cm vs females 0.57 [0.12] cm) reaching statistical significance ( P < .001). The mean height of the thyro-arytenoid muscle in males was larger than that in females on the right (males 1.05 [0.21] cm vs females 0.95 [0.12] cm) and on the left (males 1.05 [0.21] cm vs females 0.95 [0.12] cm) reaching statistical significance ( P < .01 on the right and P < .05 on the left). The volume of the thyroarytenoid muscle in males was larger than that in females on the right (males 0.86 [0.25] mL vs females 0.48 [0.15] mL) and on the left (males 0.89 [0.27] mL vs females 0.48 [0.17] mL) reaching statistical significance ( P < .001). The results of this investigation clearly indicate a significant difference in these measurements between men and women.

scholarly journals Risk Factors of Arthropathy Change of the Lateral Side of Subtalar Joint After Calcaneal Fracture Surgery

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0021
Author(s):  
Naohiro Hio ◽  
Atsushi Hasegawa ◽  
Satoshi Monden ◽  
Masanori Taki ◽  
Kazuhiko Tsunoda ◽  
...  
Keyword(s):  
Clinical Evaluation ◽  
Subtalar Joint ◽  
Calcaneal Fracture ◽  
Joint Surface ◽  
Lateral Side ◽  
Anterolateral Approach ◽  
Sinus Tarsi Approach ◽  
Mean Width ◽  
The Mean

Category: Hindfoot, Trauma Introduction/Purpose: As a result of arthropathy change on the lateral side of subtalar joint after intra-articular calcaneal fracture, the secondary disorders such as pain or restricted range of motion occasionally occur. The purpose of this study is to examine factors that cause such arthropathy change. Methods: We divided 23 joints into two groups according to arthropathy change of the lateral side of subtalar joint: the existence of such arthropathy (O) group included 8 joints, the absence of arthropathy (N) group included 15 joints. The patients’ mean age at the time of surgery were 49.1 years and 54.9 years respectively, and the mean follow-up period were 16.1 months and 12.4 months respectively. The anterolateral approach or the sinus tarsi approach was used for both groups, and the medial approach was combined as needed. The fixing materials were a plate or screws, and in some cases, staples and Kirschner wires were used in combination. We assessed Sanders classification, postoperative clinical evaluation using Creighton-Nebraska scale, and the width, height and dislocation of subtalar joint surface of calcaneus. Results: The breakdown of the Sanders classification is as follows: N group consists of 3 joints of type 2A, 7 of type 2B, 3 of type 2C, 1 of type 3BC, 1 of type 4. O group consists of 5 joints of type 2A, 2 of type 2B, 1 of type 2C. The proportion occupied by Sanders classification type 2A in O group was larger than in N group. The average of the postoperative clinical evaluation was 94.9points in N group, 86.9points in O group. In postoperative image evaluation, the mean width in the was 106.2% in N group, 117.1% in O group, the mean dislocation of the subtalar joint surface was 0.4 mm in N group and 1.1 mm in O group. Conclusion: It was suggested that Sanders type 2A and the residual dislocation of the subtalar joint surface may be a cause of arthropathy change on the lateral side of subtalar joint.

Preoperative Analysis of the Hill-Sachs Lesion in Anterior Shoulder Instability

2011 ◽  
Vol 39 (11) ◽  
pp. 2389-2395 ◽  
Author(s):  
Seung Hyun Cho ◽  
Nam Su Cho ◽  
Yong Girl Rhee
Keyword(s):  
3D Reconstruction ◽  
Shoulder Instability ◽  
Humeral Head ◽  
Postoperative Recurrence ◽  
Anterior Shoulder Instability ◽  
Level Of Evidence ◽  
Preoperative Prediction ◽  
Mean Width ◽  
The Mean ◽  
The Hill

Background: It has been reported that engagement of the Hill-Sachs lesion affects postoperative recurrence of anterior shoulder instability. However, no method has been recognized as an effective preoperative means to predict engagement of the Hill-Sachs lesion. Purpose: This study was undertaken to assess the diagnostic validity of computed tomography (CT) with 3-dimensional (3D) reconstruction to judge engagement of the Hill-Sachs lesion preoperatively. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: One hundred four consecutive patients (107 shoulders) who underwent arthroscopic Bankart repair for traumatic anterior shoulder instability were enrolled for this study. Preoperatively, CT with 3D reconstruction was performed on all patients to evaluate the size (width and depth measured on axial and coronal images), orientation (Hill-Sachs angle), and location (bicipital and vertical angles) of the Hill-Sachs lesion. Dynamic arthroscopic examination was made to confirm engagement of the Hill-Sachs lesion. Then the correlation between the results and measurements on CT images was statistically analyzed. Results: In cases of engaging lesions, the mean width was 52% (range, 27%-66%) and the mean depth was 14% (range, 8%-20%) of the humeral head diameter on axial images. The corresponding measurements on coronal images were 42% (range, 16%-67%) and 13% (range, 5%-24%), respectively. In cases of nonengaging lesions, the corresponding measurements were 40% (range, 0%-71%) and 10% (range, 0%-21%) on axial images and 31% (range, 0%-62%) and 11% (range, 0%-46%) on coronal images. The size of engaging Hill-Sachs lesions was significantly larger than that of nonengaging lesions on both axial and coronal images ( P = .001, < .001, .012, .007). The Hill-Sachs angle was 25.6° ± 7.4° in engaging lesions, which was significantly larger than 13.8° ± 6.2° in nonengaging lesions ( P < .001). The bicipital and vertical angles did not demonstrate significant correlation with engagement of the Hill-Sachs lesion ( P = .850, .584). Conclusion: On CT with 3D reconstruction images, the engaging Hill-Sachs lesions were larger in size and more horizontally oriented to the humeral shaft than nonengaging lesions. The authors concluded that preoperative prediction of the engagement of the Hill-Sachs lesion, based on these findings, would be useful in planning additional procedures to treat a significant bone defect on the humeral head.

scholarly journals Maxillary Incisive Canal Characteristics: A Radiographic Study Using Cone Beam Computerized Tomography

2019 ◽  
Vol 2019 ◽  
pp. 1-5 ◽  
Author(s):  
Penala Soumya ◽  
Pradeep Koppolu ◽  
Krishnajaneya Reddy Pathakota ◽  
Vani Chappidi
Keyword(s):  
Central Incisor ◽  
Anatomic Structure ◽  
Incisive Canal ◽  
Maxillary Central Incisor ◽  
Implant Placement ◽  
Mean Width ◽  
Immediate Implant ◽  
Thin Bone ◽  
Incisive Foramen ◽  
The Mean

Background. The incisive canal located at the midline, posterior to the central incisor, is an important anatomic structure of this area to be considered while planning for immediate implant placement in maxillary central incisor region. The purpose of the present study is to assess incisive canal characteristics using CBCT sections. Materials and Methods. CBCT scans of 79 systemically healthy patients, with intact maxillary incisors, were evaluated by two calibrated and independent examiners. Assessments included (1) mesiodistal diameter, (2) labiopalatal diameter, (3) length of the incisive canal, (4) shape of incisive canal, and (5) width of the bone anterior to the incisive foramen. Results. The mean width of the foramen labiopalatally and mesiodistally was 3.12 ± 0.94 mm and 3.23 ± 0.98 mm, respectively. Mean canal length was 18.63 ± 2.35 mm and males have significantly longer incisive canal than females. The mean width of bone anterior to the incisive canal was 6.32 ± 1.43 mm. As age of the subjects increased, incisive foramen diameter and incisive canal length were found to be increased. Cylindrical shaped incisive canals were seen in most of the individuals followed by funnel shaped and hour-glass shaped canals, and banana-like canal is least prevalent type. Conclusion. The findings from the present study suggest that the diameter and length of incisive canal vary among different individuals and presence of very thin bone anterior to the canal would suggest that a pretreatment CBCT scan is a valuable tool to evaluate anatomic variations, morphology, and dimensions of incisive foramen before immediate implant placement in maxillary central incisor region.

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