Evaluation of craniometric methods for determination of vertical dimension of occlusion--Part 2

The study examines the relationships between different craniometric distances and the nasion-gnathion (N-Gn) distance which represents the lower two thirds of the face in vertical dimension determination. The highest degree of correlation (r = 0.9217; p < 0.05) was observed between the N-Gn and zygion-zygion (Zy-Zy) distances. The N-Gn distance could be determined using the formula N-Gn = Zy-Zy/1.15 or by means of regression analysis: N-Gn = 0.54749 + 0.82822 x Zy-Zy. Considering that the coefficient of correlation between N-Gn and Zy-Zy was higher than the one between the eye-ear (E-E) and the subnasale-gnathion (Sn-Gn) distances reported earlier (r = 0.8676) it was concluded that calculating the N-Gn distance from the Zy-Zy distance was more reliable. The fact that none of the calculated correlation coefficients was 1, but was lower than 1, points to the presence of individual variations of the cephalometric parameters. Although the method cannot be taken as absolutely reliable, owing to its simplicity and practical applicability it can be recommended for use in everyday clinical practice in combination with other methods for the determination of the vertical dimension of occlusion.     

距离分析方法与杂种优势

对于75个小麦品种两年的试验结果,采用不同方法进行距离比较分析。结果表明:用表型平均值相关阵经主成分转换,计算品种间欧氏距离,再用类平均法聚类,似乎是适宜的距离分析方法。D~2值在年份间较稳定,不同年份的D~2估值,可用于预测杂种优势。根据13个性状估算的品种间距离(D~2)与株粒重杂种优势(H)之间呈曲线关系,其理论方程是:Y=-3.65 6.665X--0.1288X~2。根据该方程推算:D~2=25.87时,H出现最大值。     

Cephalometric indicators of the vertical dimension of occlusion

The aim of this investigation was to establish precise indicators of the vertical dimension of occlusion (VDO) which could be used as objective parameters in prosthodontic treatment providing exact control of the reconstructed vertical dimension of occlusion, early detection of errors and correction of the vertical dimension of occlusion during complete denture manufacturing. A total of 60 lateral cephalometric radiographs of subjects with natural dentition and class I skeletal jaw relationship, of Serbian nationality from the region of Vojvodina, were included in the investigation. Thirty subjects were males, and thirty females, their age range was 20 to 29 years. Cephalometric analysis was performed by using "Dr. Ceph" computer software (FYI Technologies, GA, USA). By evaluation of the craniofacial complex in subjects with natural dentition, horizontal dentofacial developmental growth was established in the examined sample and it was based on the relationship between the posterior and anterior total facial height (S-Go:N-Me, female X=68.96%, male X=72.8%) and statistically significant differences were found between the sexes in almost all linear dimensions and in the relation between the posterior and the anterior total facial height. Highly significant differences (p<0.001) between the sexes were found in regard to anterior total facial height (N-Me, male X=120.75 mm, female X=112.72 mm) and the anterior lower facial height (ANS-Me, male X=67.87 mm, female X=61.50 mm) (p<0.05). The proportions of the upper and lower anterior facial heights (N-ANS:ANS-Me, male X=79.36%, female X=80.63%) were within normal values in both sexes. Facial harmony existed both in men and women. Cephalometric study of the subjects with complete natural dentition included in this study provided important and specific parameters for optimal reconstruction of vertical dimension of occlusion in the treatment of edentulous patients.     

Quantitative assessment of osseous, ocular, and periocular changes after hypertelorism surgery

The purpose of this study was to develop a methodology to quantify osseous, ocular, and periocular fat changes caused by correction of orbital hypertelorism to test the hypothesis that there is a quantitatively predictable relationship between the movement of the osseous orbit and that of the ocular globe. A retrospective review was performed of 10 patients who were status post unilateral or bilateral transcranial medial orbital translocation, for whom there were archival digital data for preoperative and postoperative (mean interval = 30 months) three-dimensional computed tomographic (CT) scans. In addition to standard demographic and surgical data, the clinical preoperative and postoperative interpupillary and intermedial canthal distances were recorded. By using a computer graphics workstation, the CT digital data were registered to four surgically unaltered anatomic fiducial points to allow longitudinal quantitative comparisons. The following three-dimensional measurements were made for each patient preoperatively and postoperatively: interdacryon and interocular centroid distances, and on a standard series of three horizontal and two vertical planes, the position of the medial and lateral orbital walls, and the thickness of the medial and lateral periorbital fat (20 orbits). CT digital distances were compared with similar clinical distances when possible. The age at operation ranged from 4.0 to 12.5 years (mean, 6.6 years). The reduction in interdacryon distance exceeded the reduction in intercentroid distance (mean interdacryon change = -5.3 mm versus mean intercentroid change = -2.7 mm). Although there was a strong correlation between the amount of reduction of the lateral orbital wall and intercentroid distances, there was only a moderate correlation between the reduction in the intercentroid distance and that of the medial orbital wall. Similarly, there was a moderate correlation between the decrease in thickness of the lateral periorbital fat and the reduction of intercentroid distance but not of the medial orbital fat. In conclusion, medial translocation of the orbit does not produce equivalent movement of the ocular globe; neither the intermedial canthal nor the interdacryon distance is a useful predictor of ocular centroid position; and if the goal of hypertelorism operation is reduction of interocular distance, then CT measurement of globe intercentroid distance is essential for outcome assessment.     

吉林爆玉米遗传距离与杂种优势关系的研究

根据吉林省80个爆玉米自交系数量性状的表现,估算了它们之间的遗传距离。又估算了这80个自交系间随机组配的67个杂交组合F1代小区产量、爆粒率和膨胀倍数的杂种优势。相关和回归分析表明,F1代产量的对照优势与其双亲之间的遗传距离呈显著的二次曲线关系,而F1代品质特性爆粒率和膨胀倍数的对照优势与其双亲之间的遗传距离无确定性关系。因此,可以根据亲本间数量性状的综合遗传差异——遗传距离来预测吉林省爆玉米杂种一代的产量优势。 An experiment was conducted in 1990 to 1991 at the university,to study the relationships between genetic distance,cluster analysis and heterosis in popcorn(Zea mays var.everta).Results showed that there is no sense in cludtering parental lines for prediction of yield heterosis,but blood pedigree can beidentifed from cluster analysis.The relation between genetic divergence or distance and yield heterosis of F1 hybrids can be predicted from the genetic distances of their parental lines according to this model,but no definite relation could be found between parental genetic divergence and the quality heterosis of F1 hybrids.     

Craniofacial distraction with a modular internal distraction system: evolution of design and surgical techniques.

The present report summarizes the evolution of design for a modular internal distraction system that is applicable throughout the craniofacial region. Eleven patients (5 boys, 6 girls), whose ages ranged from 4 months to 10 years at the time of distraction, constitute the basis for this study. The clinical indications for distraction were exorbitism with corneal exposure (n = 1), obstructive sleep apnea (n = 4), tracheostomy decannulation (n = 1), severe maxillary hypoplasia with class III malocclusion (n = 3), severe vertical and sagittal maxillary deficiency with anophthalmia (n = 1), and relapse following frontoorbital advancement in a case of rare craniofacial clefting (n = 1). Twenty-two distraction devices were used in these 11 patients. Two initial prototypes were tested (prototype 1 = 8 devices; prototype 2 = 2 devices) until the modular internal distraction system (MIDS, Howmedica-Leibinger, Inc.) was developed (n = 12 devices). The craniofacial osteotomies used were Le Fort III (n = 4), monobloc (n = 3), mandibular (n = 3), Le Fort I (n = 2), and cranial (n = 1). The distraction distances ranged from 11 to 28 mm. One patient undergoing mandibular distraction developed transient swelling in the left mandibular region, which responded to antibiotics. There were no other complications. Depending on the age of the patient and the length of distraction, the distraction gap was allowed to consolidate from 6 weeks to 3 months. The devices were then removed on either an outpatient or a 23-hour-stay basis. The modular internal distraction system permits widespread application of easily customizable, buried distraction devices throughout the craniofacial region.     

Accurate estimation of inter-atomic distances in large proteins by NMR.

Recently a method was proposed which permits the extraction of the exact interatomic distance information from the measurement of the evolution of a single cross-peak relative to the mixing time in a NOESY experiment. This is performed through a careful multi-exponential analysis allowing the extraction of the relaxation parameter, and, consequently, the inter-proton distance. We investigate in the present paper whether this technique, already evaluated theoretically, can be used in a real experimental case. We have recorded and analyzed a set of 56 NOESY experiments on a lysozyme sample. Some 81 nOe build-up curves obtained from these data were analyzed in terms of distance. It is shown that the correlation between the measured distances and the reference distances obtained from crystallographic studies, is quite good. An accuracy of the order of 10% is obtained.     

Familial correlations of variables from the craniofacial complex in a Venezuelan isolate of African origin

Familial aggregation for 33 different variables from the craniofacial complex was estimated through intraclass correlation coefficients for four different relationships: parent-offspring paris, sibs, cousins and unrelated pairs. The population chosen for the study was La Sabana, D.F., a Venezuelan isolate of Negroid origin. The general tendency observed among the different correlations was as anticipated: sibs show higher correlations than cousins and these were higher than for unrelated pairs. Parent-offspring correlations were lower than expected. The significant correlations observed among sibs for 17 of the variables indicate aggregation due to genetic and/or common environmental factors. On the other hand, little genetic determination was detected for sella-C point distance or for upper dental arch depth both of which show intraclass sib correlations ≤0.1.     

Surnames in Texas: a population study through isonymy

To study the isonymy structure of Texas, we analyzed the surname distributions of 3.6 million telephone users registered for the year 1996 in 232 towns distributed in the 7 regions of the state. The number of different surnames was 235,740. Matrices of isonymy distances between towns and between geographic regions were constructed and tested for correlation with geographic distance. We found that isonymy distances between the seven regions showed borderline or no correlation with geographic distance, with r = 0.089 +/- 0.232, r = 0.492 +/- 0.232, and r = 0.337 +/- 0.232 for Lasker's, Euclidean, and Nei's distances, respectively. Isonymy distances between towns were significantly correlated with geographic distance, with r = 0.249 +/- 0.006 for Lasker's distance, r = 0.338 +/- 0.006 for the Euclidean distance, and r = 0.418 +/- 0.006 for Nei's distance. Two dendrograms, one for the 7 regions and one for the 232 towns, were built from the matrices of Nei's distances. The dendrogram for regions indicates that a main surname differentiation exists between the East and West areas of Texas, with West Texas being predominantly Hispanic and East Texas being predominantly English-speaking. The dendrogram for the towns confirms in detail the differences identified by the matrix of distances between regions. Random inbreeding calculated from isonymy, F(ST), was highest in the west and in the south of the state. It was lowest in the area of Austin and Houston. Average Fisher's alpha for towns was 734, for regions it was 1,047, and for Texas as a whole it was 1,230. The geographic distribution of alpha in the state shows distinctly lower values in the traditionally Hispanic west and higher values in the east and on the Gulf of Mexico.     

用氨基葡萄糖含量的测定值间接表示红曲菌固态发酵过程中生物量的研究

【目的】为准确快速地了解紫色红曲菌固态发酵中生物量的变化,【方法】采用理化方法测定菌体量和氨基葡萄糖含量,研究了不同培养时间、培养基组成、培养方式下菌体量与氨基葡萄糖含量的关系,建立生物量和氨基葡萄糖含量的换算关系式;构建关联该菌固态培养物近红外光谱数据与实测氨基葡萄糖含量的PLS模型。【结果】建立了可通过近红外光谱法测定氨基葡萄糖来快速预测固态发酵生物量的方法,其中最优近红外模型的校正集内部交叉验证均方根误差(RMSECV)为0.209 4,预测集相关系数(Rp)和均方根误差(RMSEP)分别为0.993 4和0.217 3;同时利用所建的换算关系式也大大提高了生物量计算的准确性。【结论】基于所建立的生物量和氨基葡萄糖的换算关系式,利用近红外光谱法可以快速并且较准确地测定紫色红曲菌固态发酵过程中生物量的变化。     

Accuracy of elastic property measurement in mandibular cortical bone is improved by using cylindrical specimens

Ultrasonic determination of elastic properties in human craniofacial cortical bone is problematic because of a lack of information about the principal material axes, and because the cortex is often thinner than in long bones. This study investigated solutions that permit reasonable determination of elastic properties in the human mandible. We tested whether ultrasonic velocities could be reliably measured in cylindrical samples of aluminum and mandibular bone, and the effects of reduced specimen thickness. Results indicted that (1) varying shape had minimal effects on ultrasonic velocities or derived elastic properties, and (2) ultrasonic velocities have relatively increased measurement error as propagation distances decreased. The increased error in velocity measurements of mandibular cortical specimens of less than 1.2 mm in thickness should be considered when assessing the reliability of single measurements.     

A linear function for the approximation of accessible surface area of proteins

Since the solvent accessible surface area of proteins has been utilized as an important factor in the prediction of their thermodynamic properties, a simple and analytical method for its determination would contribute to protein structure prediction and analysis methods. We report the development of a simple and analytical method for the estimation of the accessible surface area of protein, consisting of linear functions of distances between unified atoms. While our formulation was much simpler than previously developed methods, it showed comparable performance, with the mean relative error on total solvent accessible surface area of 0.49 and 2.16% for 89 denatured and native protein structures, respectively. Moreover, the partial derivatives of accessible surface area to the position of unified atoms could also be derived in a simpler form.     

Use of digital photographs for artificial tooth selection

Digital photography has become available to everybody. The aim of this study was to examine possibility of calculating the width of a missing central incisor using digital photographs. Digital photographs were obtained from 51 dentate subjects using a 3.1 Megapixel digital camera from various distances: 35 cm, 70 cm, 1 m and 1.5 m. For the calculation of the width of maxillary left central incisor (MLI), the following equation was used: MLI(calculated) = Photographic width of MLI x IPD / photographic IPD. Statistical analysis was made (Kolmogorov-Smirnov test, dependent sample t-test, correlation and frequencies) using SPSS 10.0 for Windows. Results revealed no significant difference between the calculated MLI (70 cm, 1 m and 1.5 m distance) and actual MLI, however calculated MLI from 35 cm distance was significantly different from the actual MLI value (p < 0.01). The highest correlation was between calculated MLI (70 cm distance) and actual MLI. However, the highest percentage of results from a distance of 70 cm also fitted within +/- 0.3 mm; +/- 0.5 mm and +/- 1 mm difference from the actual MLI values. However, the results obtained from 1 m distance were also satisfactory. The technique of use of digital photography is of proven value in calculating the width of a maxillary central incisor. The photographs using a simple digital camera should be taken from a distance from 70 cm to 1 m. Saving such photographs in a dental office may eventually be helpful for calculating dimensions of artificial teeth.     

Distance evaluation via heteronuclear SQC-NOESY experiments

Summary A method for the quantitative determination of interproton distances from¹H NOE relayed heteronuclear correlation is presented. Model compounds are investigated. Accurate distances are obtained if all the factors affecting such distance measurements, such as the local mobility and the presence of strong coupling in heteronuclear systems, are properly taken into account.     

Determining undergraduate curriculum content in plastic surgery

The purpose of this study was to determine the cognitive knowledge and clinical skills related to plastic surgery that are essential for inclusion in an undergraduate curriculum. A questionnaire was distributed to surgical clerkship directors, plastic surgeons, and 1980 graduates of four medical schools. Respondents were asked to rate (0-3) the importance of 74 knowledge items and 28 clinical skills in relation to the knowledge/proficiency necessary for students to achieve prior to graduating from medical school (0 = unnecessary, 3 = indepth knowledge/proficiency important). Results of the questionnaire enabled the determination of mean response scores and the hierarchical ranking of questionnaire items. There was a high degree of correlation between the rankings of the three groups of respondents indicating agreement on knowledge and clinical skills in plastic surgery that are essential, as well as those nonessential, for the competent practice of medicine.     

Solution structure of a LewisX analogue by off-resonance 1H NMR spectroscopy without use of an internal distance reference

Summary A recent ¹H NMR method has been applied to the determination of the solution structure and internal dynamics of a synthetic mixed C/O trisaccharide related to sialyl Lewis^x. Varying the rf field offset in ROESY-type experiments enabled the measurement of longitudinal and transverse dipolar cross-relaxation rates with high accuracy. Assuming that for each proton pair the motion could be represented by a single exponential autocorrelation function, it was possible to derive geometrical parameters (r) and dynamic parameters _cp. With this assumption, 224 cross-relaxation rates have been transformed into 30 interproton distance constraints and 30 dipolar correlation times. The distance constraints have been used in a simulated-annealing procedure. This trisaccharide exhibits a structure close to the O-glycosidic analogue, but its flexibility seems highly reduced. On the basis of the determined structure and dynamics, it is shown that no conformational exchange occurs, the molecule existing in the form of a unique family in aqueous solution. In order to assess the quality of the resulting structures and to validate this new experimental procedure of distance extraction, we finally compare these solution structures to the ones obtained using three different sets of distances deduced from three choices of internal reference. It appears that this procedure allows the determination of the most precise and accurate solution.Abbreviations COSY correlation spectroscopy - NOE nuclear Overhauser enhancement - NOESY nuclear Overhauser enhancement spectroscopy; rmsd, root-mean-square deviation - ROESY rotating frame Overhauser enhancement spectroscopy - SLe^x sialyl Lewis^x - TOCSY total correlation spectroscopy     

Effects of dynamic warm-up on lower body explosiveness among collegiate baseball players

Debate exists between the benefits and effectiveness of a dynamic warm-up vs. a static warm-up. This study was conducted to compare dynamic and static warm-ups on lower body explosiveness as measured by stationary vertical jump (VJ) and standing long jump (LJ) among collegiate baseball players. Participants (n = 17; age = 19.59 ± 1.37 years) progressed through 3 different warm-ups on weekly testing dates over a 7-week period. After the warm-up routines, participants were measured for VJ height and LJ distance in centimeters. The mean jump heights for VJ were 66.49 ± 8.28 cm for dynamic, 61.42 ± 7.51 cm for static, and 62.72 ± 7.84 cm for the control condition. The mean jump distances for LJ were 231.99 ± 20.69 cm for dynamic, 219.69 ± 20.96 cm for static, and 226.46 ± 20.60 cm for the control. Results indicated that the participants jumped significantly higher in both experimental conditions while under the influence of the dynamic warm-up (VJ-F = 22.08; df = 1.33, 21.345; p < 0.00 and LJ-F = 32.20; df = 2, 32; p < 0.01). Additional LJ analysis determined that individuals jumped significantly further after no warm-up compared to after a static warm-up (-6.78, p < 0.05). Lower body explosiveness is critical in baseball and many other sports as well. The results show that dynamic warm-up increases both VJ height and LJ distance. Specifically, these findings indicate that athletes could gain nearly 2 in. on his or her vertical jump by simply switching from a static warm-up routine to a dynamic routine.     

An update of the world survey of myrmecochorous dispersal distances

We update the global assessment of seed dispersal by ants and test the hypothesis that the body size of seed‐dispersing ant species varies with latitude in the same way as dispersal distance. We compiled all published data about seed dispersal distance by myrmecochory through March, 2011. We then broke the data down by vegetation type, geography and taxonomy. We also compiled data on body size (body length) of the seed‐dispersing ant species from the studies consulted. Based on 7889 observations, the mean dispersal distance was 1.99 m, although the curve has a long tail extending to 180 m. Considering the mean dispersal distance by ant species and study as independent data, the mean dispersal distance was 2.24 ± 7.19 m (n = 183). Shorter distances are associated with smaller ant species, while the tail of the dispersal curve is due to larger ant species. The mean dispersal distance of myrmecochorous seeds dispersed by ants decreased with increasing latitude, but there was no significant relationship between the body size of dispersing ant species and latitude (i.e. myrmecochorous seed‐dispersing ant species do not follow Bergmann's rule). In 1998 we made three predictions: 1) the dispersal distances of the Southern Hemisphere will decrease with as more data from mesophyllous vegetation are obtained; 2) assuming that ant nest density is higher at lower latitudes, the differences in distances between hemispheres would probably decrease with more data; and 3) numerical differences between dispersal distances in mesophyllous and sclerophyllous vegetation zones would increase with more data. The results obtained since 1998 support the only the third prediction. The dispersal distances in mesophyllous vegetation zones are shorter than in the sclerophyllous vegetation zones, and the difference between 1998 have increased. The differences in dispersal distances between hemispheres are consistent with the avoidance of parent–offspring competition (escape hypothesis).     

Haptic Discrimination of Distance

While quite some research has focussed on the accuracy of haptic perception of distance, information on the precision of haptic perception of distance is still scarce, particularly regarding distances perceived by making arm movements. In this study, eight conditions were measured to answer four main questions, which are: what is the influence of reference distance, movement axis, perceptual mode (active or passive) and stimulus type on the precision of this kind of distance perception? A discrimination experiment was performed with twelve participants. The participants were presented with two distances, using either a haptic device or a real stimulus. Participants compared the distances by moving their hand from a start to an end position. They were then asked to judge which of the distances was the longer, from which the discrimination threshold was determined for each participant and condition. The precision was influenced by reference distance. No effect of movement axis was found. The precision was higher for active than for passive movements and it was a bit lower for real stimuli than for rendered stimuli, but it was not affected by adding cutaneous information. Overall, the Weber fraction for the active perception of a distance of 25 or 35 cm was about 11% for all cardinal axes. The recorded position data suggest that participants, in order to be able to judge which distance was the longer, tried to produce similar speed profiles in both movements. This knowledge could be useful in the design of haptic devices.