6,553 research outputs found

    Revealing tensor monopoles through quantum-metric measurements

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    Monopoles are intriguing topological objects, which play a central role in gauge theories and topological states of matter. While conventional monopoles are found in odd-dimensional flat spaces, such as the Dirac monopole in three dimensions and the non-Abelian Yang monopole in five dimensions, more exotic objects were predicted to exist in even dimensions. This is the case of "tensor monopoles", which are associated with generalized (tensor) gauge fields, and which can be defined in four dimensional flat spaces. In this work, we investigate the possibility of creating and measuring such a tensor monopole, by introducing a realistic three-band model defined over a four-dimensional parameter space. Our probing method is based on the observation that the topological charge of this tensor monopole, which we relate to a generalized Berry curvature, can be directly extracted from the quantum metric. We propose a realistic three-level atomic system, where tensor monopoles could be generated and revealed through quantum-metric measurements.Comment: 4+4 pages, 2 figures, Revised version containing new appendice

    Calibration by correlation using metric embedding from non-metric similarities

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    This paper presents a new intrinsic calibration method that allows us to calibrate a generic single-view point camera just by waving it around. From the video sequence obtained while the camera undergoes random motion, we compute the pairwise time correlation of the luminance signal for a subset of the pixels. We show that, if the camera undergoes a random uniform motion, then the pairwise correlation of any pixels pair is a function of the distance between the pixel directions on the visual sphere. This leads to formalizing calibration as a problem of metric embedding from non-metric measurements: we want to find the disposition of pixels on the visual sphere from similarities that are an unknown function of the distances. This problem is a generalization of multidimensional scaling (MDS) that has so far resisted a comprehensive observability analysis (can we reconstruct a metrically accurate embedding?) and a solid generic solution (how to do so?). We show that the observability depends both on the local geometric properties (curvature) as well as on the global topological properties (connectedness) of the target manifold. We show that, in contrast to the Euclidean case, on the sphere we can recover the scale of the points distribution, therefore obtaining a metrically accurate solution from non-metric measurements. We describe an algorithm that is robust across manifolds and can recover a metrically accurate solution when the metric information is observable. We demonstrate the performance of the algorithm for several cameras (pin-hole, fish-eye, omnidirectional), and we obtain results comparable to calibration using classical methods. Additional synthetic benchmarks show that the algorithm performs as theoretically predicted for all corner cases of the observability analysis

    A Preliminary Investigation Comparing Craniofacial Metric Measurements and 3D Virtual Measurements

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    The development and advancement of new laser scanning techniques enables the capture of 3D imaging which can be quantitatively assessed for use on the human skull. I used a Polhemus Fast Scan Scorpion scanner to scan 8 skulls and evaluated the standard 24 metric measurements in Delta analysis software in comparison to standard metric measurements. The scanned measurements were then compared to the standard metric measurements using the same landmarks. Of the original 48 measurements, 33 (68.75%) fail to reject the null and 10 (20.83%) reject the null with the remaining 5 (10.41%) being unknown due to n=1 because of skull damage. The measurements that proved highly reliable were those associated with specific landmarks, and not those measurements that are based on landmarks and feel and considered arbitrary in this study. This study indicates that the use of the laser scanner can be a useful tool for rapid acquisition of skeletal and anatomical surfaces however, accurate location of landmarks and operator skill are of utmost importance in achieving accurate and reliable results

    A new broadband square law detector

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    A broadband constant law detector was developed for precision power measurements, radio metric measurements, and other applications. It has a wide dynamic range and an accurate square law response. Other desirable characteristics, which are all included in a single compact unit, are: (1) high-level dc output with immunity to ground loop problems; (2) fast response times; (3) ability to insert known time constants; and (4) good thermal stability. The detector and its performance are described in detail. The detector can be operated in a programmable system with a ten-fold increase in accuracy. The use and performance of the detector in a noise-adding radiometer system is also discussed

    Sexual dimorphism: metric measurements based study in human talus bone

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     Background: Identification is the act of establishing the identity of an individual. This is a dynamic process and human remains in form of bones can serve as an excellent tool for establishing the sexual identity of the deceased, along with other methods such as DNA, fingerprints, blood group identification etc. Metric analysis of various bones can serve as a viable alternative in cases when morphological analysis is not possible due to damage to the skeletal remains or as an additive analytical tool to establish a positive identity.Methods: Metric analysis of various parameters of randomly selected 100 pairs of human talus bones (50 male and 50 female) as a means of establishing sexual identity from skeletal remains obtained from unidentified and unclaimed dead bodies brought for autopsy.Results: In the present study we found that the values of all the various dimensions measured were higher among the male subjects as compared to that in female samples as was expected. On further analysis, this difference was found to be statistically significant (p<0.001). For the right sided and left sided talus bone, the probable accuracy for various parameters ranged between 83.3% to 100% each, thus indicating strong correlation between sex of the subject and various measurements.Conclusions: The tarsal and their dimensions are highly sexually dimorphic and are useful in determining sex in individuals of this region

    Metric conversion for agriculture

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    Farmers are already becoming involved with metric units and by 1974 conversion of the farming industry will be well advanced. Wool sales converted to metric measurements in August, 1971, and sales by the various grain marketing boards will be largely in metric terms in the 1972 harvest. Weather information to the public has been given in metric terms since September 1

    Sexual Dimorphism Of The Posterior Pelvis Of The Robert J. Terry Anatomical Collection And The William M. Bass Donated Skeletal Collection

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    Studies of sexual dimorphism of the sacrum have generally been conducted as part of broader population research or on living persons and cadavers, making the anthropological literature sparse. The greater sciatic notch and the preauricular sulcus of the ilium have both been found to show sexual dimorphism, although studies of these traits often have ambiguous definitions of characteristics and lack the standardization of measurements. This research was designed to reexamine and test the accuracy of standard scoring systems and measurements of the posterior pelvis used to determine sex and to establish new formulae combining traits and measurements to accurately determine sex using logistic regression analysis. A series of metric measurements and morphological scores were recorded for 104 males and 106 females of both European- and African-American ancestry from the William M. Bass and Terry Collections. In order to reexamine previous research conducted on the posterior pelvis, standard ratios of metric measurements were analyzed to determine ranges and cut-off values for males and females in this sample. The ratio of ala width to the maximum transverse diameter of the sacral base and the ratio of the length and width of the sciatic notch have proven to be the most useful ratios in sex determination, though not as accurate as the formulae created using logistic regression. These data were also analyzed in SPSS using logistic regression to assess the usefulness of metric measurements and morphological scores of the posterior pelvis in sex determination. Using stepwise logistic regression, a combination of traits for both the sacrum and posterior ilium that are the most reliable and accurate for sex determination have been determined. The values for these selected traits can be incorporated into the log odds formulas which will classify an individual as male or female. The ultimate goal of this research was to provide physical anthropologists with iii logistic regression equations that can be used to estimate the sex of the posterior ilium and sacrum. Two equations ranging in accuracy from 79-84% were developed to determine sex of the posterior pelvis

    3D CBCT analysis of the frontal sinus and its relationship to forensic identification

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    Indiana University-Purdue University Indianapolis (IUPUI)The positive identification of human remains that are decomposed, burnt, or otherwise disfigured can prove especially challenging in forensic anthropology, resulting in the need for specialized methods of analysis. Due to the unique morphological characteristics of the frontal sinus, a positive identification can be made in cases of unknown human remains, even when remains are highly cremated or decomposed. This study retrospectively reviews 3D CBCT images of a total of 43 Caucasian patients between the ages of 20-38 from the Indiana University School of Dentistry to quantify frontal sinus differences between adult males and females and investigate the usefulness of frontal sinus morphology for forensic identification. Digit codes with six sections and eleven-digit numbers were created to classify each individual sinus. It was shown that 3D CBCT images of the frontal sinus could be used to make a positive forensic identification. Metric measurements displayed a high degree of variability between sinuses and no two digit codes were identical. However, it was also shown that there were almost no quantifiable and significant sexually dimorphic differences between male and female frontal sinuses. This study confirms that sex determination should not be a primary goal of frontal sinus analysis and highlights the importance of creating a standard method of frontal sinus evaluation based on metric measurements

    Metric measurements and attachment levels of the medial patellofemoral ligament: an anatomical study in cadavers

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    OBJECTIVE: To determine the metric measurements and to verify the attachment levels of the medial patellofemoral ligament in human cadavers. METHODS: Seventeen knees (eight right and nine left knees) from 10 cadavers (nine male and one female) were dissected and stored in a 10% formaldehyde solution. All of the knees were whole and did not show any macroscopic signs of injuries. RESULTS: The medial patellofemoral ligament was present in 88% of the knees studied, localized transversally between the medial femoral epicondyle and the medial margin of the patella. Its dimensions were quite variable, even between the knees of the same individual. The width of the patellar insertion ranged from 16 to 38.8 mm, with a mean of 27.90 mm, and its mean length was 55.67 mm. The margins of the ligament were concave or rectilinear. At the upper margin, the concave form predominated and was better characterized, while at the lower margin, the rectilinear form predominated. CONCLUSIONS: The medial patellofemoral ligament is a very distinct structure with variable anatomical aspects and is always located in a plane inferior to the vastus medialis obliquus muscle
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