Search

Unit cell volumes of Mo and Pt have been measured simultaneously to ≈400 GPa by x-ray powder diffraction using a diamond anvil cell and synchrotron radiation source. The body-centered cubic (bcc) phase of Mo was found to be stable up to 410 GPa. The equation of state (EOS) of bcc-Mo was determined on the basis of Pt pressure scale. A fit of Vinet EOS to the volume compression data gave K0 = 262.3(4.6) GPa, K0′ = 4.55(16) with one atmosphere atomic volume V0 = 31.155(24) A3. The EOS was in good agreement with the previous ultrasonic data within pressure difference of 2.5%–3.3% in the multimegabar range, though the EOS of Mo proposed from a shock compression experiment gave lower pressure by 7.2%–11.3% than the present EOS. The agreement would suggest that the Pt pressure scale provides an accurate pressure value in an ultra-high pressure range.

The paper specifies a novel coder/decoder that compresses sequences of 3D texture data to support the haptic rendering of animated volumes. Lossy compression gives 25% of the original size. Lossy compression and clipping gives 3% but requires the renderer to query for new data when the point of contact moves. We evaluated the codec by means of rendering volumes on a 3-DOF Phantom 1.5A that simulated viscosity for each texture element. In this setting, we studied the impact of information loss in controlled experiments. We validated that our codec preserves haptic perception. An area of application is the development of network-distributed virtual environments that generate visual and haptic feedback

BACKGROUND: Three-dimensional ultrasound images allow virtual sonography even at a distance. However, the size of final 3-D files limits their transmission through slow networks such as the Internet. OBJECTIVE: To analyze compression techniques that transform ultrasound images into small 3-D volumes that can be transmitted through the Internet without loss of relevant medical information. METHODS: Samples were selected from ultrasound examinations performed during, 1999-2000, in the Obstetrics and Gynecology Department at the University Hospital in La Laguna, Canary Islands, Spain. The conventional ultrasound video output was recorded at 25 fps (frames per second) on a PC, producing 100- to 120-MB files (for from 500 to 550 frames). Processing to obtain 3-D images progressively reduced file size. RESULTS: The original frames passed through different compression stages: selecting the region of interest, rendering techniques, and compression for storage. Final 3-D volumes reached 1:25 compression rates (1.5- to 2-MB files). Those volumes need 7 to 8 minutes to be transmitted through the Internet at a mean data throughput of 6.6 Kbytes per second. At the receiving site, virtual sonography is possible using orthogonal projections or oblique cuts. CONCLUSIONS: Modern volume-rendering techniques allowed distant virtual sonography through the Internet. This is the result of their efficient data compression that maintains its attractiveness as a main criterion for distant diagnosis. [J Med Internet Res 2001;3(2):e21]

Volume compression and volume ignition of laser compressed pellets has an enormous advantage against spark ignition since the alpha self-heat substantially contributes as an additional stimulation of nuclear fusion reactions. We present here improved computations of volume ignition in agreement with the classical fact that the generated fusion energy is larger than the bremsstrahlung energy in DT only at temperatures above 4·5 keV. This result is in very close agreement with Kidder's (1974) values, and in agreement with recent computations of Mimaet al.(1987). The extension of these calculations to higher densities and input energies results in the self-absorption of bremsstrahlung at an initial temperature of about 1 keV only, much below the classical 4·5 keV. A fuel burnup fraction above 80% is shown to be possible.

In view of the possible difficulties for the tokamak fusion reactor concept by reason of too high costs according to the Pfirsch-Schmitter result, the basically simpler and spatially highly concentrated pellet fusion reactor of the CASCADE type might be of interest. The only question is how pellet fusion will be realized, though the present day fusion gains by laser fusion are at least as good as that of tokamaks despite ten times less funding for laser fusion. The turning point for laser fusion is the fact achieved by Yamanaka and Nakai that a volume compression with the highest gains can be verified experimentally, for which case it has been shown already that volume ignition does lead to reactor appropriate moderate compression to only 50 times the solid state density for laser pulses in the MJ range.

This clinical report describes how a hollow obturator prosthesis was designed and fabricated for an 82-year-old partially edentulous patient with a large palatal defect. Computer-aided design (CAD) was used to design, articulate, and align the mandibular denture with the obturator prosthesis. The prosthesis was printed, adjusted chairside, rescanned, and made hollow by using a CAD software program. The prosthesis was printed in resin with a dental 3D printer. Quantitative evaluations of clinical (prosthesis dimensions, rest, and occlusal vertical dimensions) and virtual (surface area, volume, weight, interpoint mismatches, spatial overlap) parameters found that the 3D-printed prosthesis required an additional 5% chairside modification. The greatest differences in volume (24.7% less) and weight (22.2% less) were observed when the modified obturator bulb was made hollow via CAD. Hollowing the bulb, therefore, reduced the spatial overlap in volume by 16.8%.

The isothermal linear and volume compressions of the explosive pentaerythritol tetranitrate (PETN) were measured to 10 GPa using a high pressure x‐ray diffraction technique. The fits to the data are a/a0 = 1−2.052×10−2P + 2.230×10−3P2 − 1.041×10−4P3, and c/c0 = 1−2.832×10−2P + 3.295×10−3P2 − 1.458×10−4P3, for P

Hydrostatic compression data for a number of high-pressure phases of oxides and silicates, which have been studied independently by acoustic techniques, have been analyzed by least-squares fitting of the Birch-Murnaghan equation of state to determine the zero-pressure bulk modulus K0 and its pressure derivative K′0 for each material. The standard deviations of K0 and K′0 so determined are generally underestimated unless the experimental errors in the measurements of volume and pressure are explicitly included. When the values of K0 determined from the acoustic and compression techniques are consistent, test results for quartz and rutile demonstrate that constraining K0 to be equal to the acoustic value significantly improves both the accuracy and the precision of K′0 obtained from the compression data. Similar analyses for high-pressure phases (e.g., pyrope garnet and silicate spinels) indicate that by combining the acoustic and P-V data, the standard deviation of K′0 is typically reduced by a factor of three. Thus, we conclude that this approach does allow precise determinations of K′0 even when neither technique alone is able to resolve this parameter. For some materials, however, the P-V and acoustic experiments do not define mutually consistent values of K0, invalidating any combination of these data. The compression data for stishovite clearly exhibit run to run effects, and we infer that systematic errors are present in some of the P-V data which are responsible for many of the interlaboratory inconsistencies. Such systematic biases in the P-V data can at least be partially compensated for by performing several duplicate experimental runs.

Classical criterion to define the ignition temperature as the point where fusion-born charged particle energy deposition (per time unit) exceeds radiation losses power is not applicable to Inertial Fusion target with areal densities of 1 g/cm2 or higher. Radiation reabsorption and neutron energy deposition must be taken into account in the onset of the fusion burst. This paper presents an analytical explanation of the main mechanisms governing the evolution of a volume-compressed target. It is shown that inherent energy gains higher than 103 can be achieved.

Constant pressure and temperature molecular dynamics techniques have been employed to investigate the changes in structure and volumes of two globular proteins, superoxide dismutase and lysozyme, under pressure. Compression (the relative changes in the proteins' volumes), computed with the Voronoi technique, is closely related with the so-called protein intrinsic compressibility, estimated by sound velocity measurements. In particular, compression computed with Voronoi volumes predicts, in agreement with experimental estimates, a negative bound water contribution to the apparent protein compression. While the use of van der Waals and molecular volumes underestimates the intrinsic compressibilities of proteins, Voronoi volumes produce results closer to experimental estimates. Remarkably, for two globular proteins of very different secondary structures, we compute identical (within statistical error) protein intrinsic compressions, as predicted by recent experimental studies. Changes in the protein interatomic distances under compression are also investigated. It is found that, on average, short distances compress less than longer ones. This nonuniform contraction underlines the peculiar nature of the structural changes due to pressure in contrast with temperature effects, which instead produce spatially uniform changes in proteins. The structural effects observed in the simulations at high pressure can explain protein compressibility measurements carried out by fluorimetric and hole burning techniques. Finally, the calculation of the proteins static structure factor shows significant shifts in the peaks at short wavenumber as pressure changes. These effects might provide an alternative way to obtain information concerning compressibilities of selected protein regions.

Scientific simulations on high-performance computing (HPC) systems can generate large amounts of floating-point data per run. As compared to lossless compressors, lossy compressors, such as SZ and ZFP, can reduce data volume more aggressively while maintaining the usefulness of the data. However, a reduction ratio of more than two orders of magnitude is almost impossible without seriously distorting the data. In deep learning, the autoencoder has shown potential for data compression. Whether the autoencoder can deliver similar performance on scientific data, however, is unknown. In this paper, we for the first time conduct a comprehensive study on the use of autoencoders to compress real-world scientific data and illustrate several key findings on using autoencoders for scientific data reduction. We implement an autoencoder-based compression prototype to reduce floating-point data. Our study shows that the out-of-the-box implementation needs to be further tuned in order to achieve high compression ratios and satisfactory error bounds. Our evaluation results show that, for most test datasets, the tuned autoencoder outperforms SZ by 2 to 4X, and ZFP by 10 to 50X in compression ratios, respectively. Our practices and lessons learned in this work can direct future optimizations for using autoencoders to compress scientific data.

Background: The relationship between anterior cruciate ligament (ACL) injury and anatomical structures is still a topic of debate. Purpose: The aim of this study was to compare knee geometry in demographically matched ACL-injured and ACL-intact athletes. Methods: We conducted a case-control study comparing 2 groups, each consisting of 55 professional athletes (44 men and 11 women): 1 group with complete ACL tears (cases) and 1 group with intact ACLs (controls). The groups were compared using magnetic resonance imaging (MRI) in terms of intercondylar notch geometry, tibial plateau characteristics, and ACL volume. Results: Among cases and controls, we found the cases had lower notch width (20.24 ± 2.68 mm vs. 22.04 ± 2.56 mm, respectively) and notch width index (0.29 ± 0.03 vs. 0.31 ± 0.03, respectively). The mean ACL volume in the cases (1181.63 mm3 ± 326 mm3) was also lower than in controls (1352.61 mm3 ± 279.84 mm3). The parameters of tibial slope geometry were comparable between groups. In addition, women had lower ACL volume than men (1254 ± 310 mm3 vs. 890 ± 267 mm3, respectively) and higher medial posterior tibial slope (4.76 ± 2.6 vs. 6.63 ± 1.83, respectively). Among cases, women had narrower notch width than men (16.9 ± 2.42 mm vs. 21.08 ± 2.03 mm). However, notch width index was comparable between male (0.3 ± 0.02) and female (0.28 ± 0.03) cases. Conclusion: Our findings suggest that narrow notch width and low ACL volume may enhance the risk of ACL injury among athletes. There was no association found between posterior tibial slope and ACL injury between athletes with injured ACLs and controls. Further study is indicated.

Background The majority of fetal structural defects can be detected in the second trimester, thus this is the main time for screening for structural defects. 3D imaging of the fetal brain does not create a common part of this screening. Methods This prospective observational study was conducted at the Fetal Medicine Center of The Gynecological-Obstetrical Department of the University Hospital Olomouc in years 2017- 2020. The study sample was 451 consecutively scanned morphologically normal fetuses attending for routine second trimester anatomical survey at 20-22 weeks of pregnancy. A transabdominal 3D ultrasound volume acquisition of fetal brain was obtained from an axial and sagittal plane using skull sutures as an acoustic window. Results Both the corpus callosum (CC) and the vermis (VC) were detected in 51.7% of examinations in the sagittal plane, and in 31.7% in the axial plane. In 61.9% of the examinations, there was at least partial detection in both planes. Maternal BMI was found to be the only significant predictor of the quality of imaging in both planes. Conclusion 3D acquisition of fetal brain images in the sagittal plane followed by manipulation of acquired volume was valuable in assessment of corpus callosum and cerebellar vermis. This allows reconstruction of the sagittal plane that can be difficult to obtain in 2D imaging.

Background: Tumor regression grade (TRG) correlates with prognosis in patients with locally advanced rectal cancer (LARC), but there is controversy regarding the use of magnetic resonance imaging (MRI) for determining TRG. This study to evaluate the diagnostic value of change rate in signal intensity (SI) and volume (V) from MRI to TRG following preoperative chemoradiotherapy (CRT) in patiens with LARC.Materials and methods: This retrospective analysis examined 82 LARC patients who were admitted to our institution between Oct 2017 and Oct 2019. Patients underwent pre- and post-CRT T2-weighted (T2W), diffusion-weighted (DW)/apparent diffusion coefficient (ADC), and contrast-enhanced T1-weighted (ceT1W) MRI. Change rate of volume and relative SI ratio(%△V and %△SIR) from each sequence were determined. All LARCs were confirmed pathologically and classified into TRG 0, 1, 2 and 3. Descriptive statistics and receiver operating characteristic (ROC) analysis, with calculation of area under the curve (AUC), were used to compare the diagnostic performances. Results: Sixteen patients had TRG-0, 15 had TRG-1, 35 had TRG-2, and 16 had TRG-3. Except for ADC-%△SIR, the remaining%△V and %△SIR on T1W, DWI, and ceT1W had significant differences among the four groups. %△V and/or %△SIR did not distinguish TRG-1 from TRG-2 nor TRG-2 from TRG-3, but differences between other TRGs were identified by %△V and/or %△SIR on T2W, DWI, and ceT1W. The combined use of DW-%△V and T2W-%△SIR provided the best diagnostic performance in distinguishing of TRG-0 from TRG-2 (AUC: 0.954) and from TRG-3 (AUC: 1.000).Conclusions: Preoperative MRI of LARC patients can determine TRG and may improve selection of the preoperative therapy.

Statement of problem The anatomic complexity of the ear challenges conventional maxillofacial prosthetic rehabilitation. The introduction of specialized scanning hardware integrated into computer-aided design and computer-aided manufacturing (CAD-CAM) workflows has mitigated these challenges. Currently, the scanning hardware required for digital data acquisition is expensive and not readily available for prosthodontists in developing regions. Purpose The purpose of this virtual analysis study was to compare the accuracy and precision of 3-dimensional (3D) ear models generated by scanning gypsum casts with a smartphone camera and a desktop laser scanner. Material and methods Six ear casts were fabricated from green dental gypsum and scanned with a laser scanner. The resultant 3D models were exported as standard tessellation language (STL) files. A stereophotogrammetry system was fabricated by using a motorized turntable and an automated microcontroller photograph capturing interface. A total of 48 images were captured from 2 angles on the arc (20 degrees and 40 degrees from the base of the turntable) with an image overlap of 15 degrees, controlled by a stepper motor. Ear 1 was placed on the turntable and captured 5 times with smartphone 1 and tested for precision. Then, ears 1 to 6 were scanned once with a laser scanner and with smartphones 1 and 2. The images were converted into 3D casts and compared for accuracy against their laser scanned counterparts for surface area, volume, interpoint mismatches, and spatial overlap. Acceptability thresholds were set at 0.70 for spatial overlap. Results The test for smartphone precision in comparison with that of the laser scanner showed a difference in surface area of 774.22 ±295.27 mm2 (6.9% less area) and in volume of 4228.60 ±2276.89 mm3 (13.4% more volume). Both acceptability thresholds were also met. The test for accuracy among smartphones 1, 2, and the laser scanner showed no statistically significant differences (P>.05) in all 4 parameters among the groups while also meeting both acceptability thresholds. Conclusions Smartphone cameras used to capture 48 overlapping gypsum cast ear images in a controlled environment generated 3D models parametrically similar to those produced by standard laser scanners.

The topics of sub-specialization and regionalization of care have garnered increased attention among pediatric surgeons. Thyroid surgeries are one such sub-specialty and are commonly concentrated within practices. A national survey was conducted examining current surgeon practices and beliefs surrounding pediatric thyroid surgery.Non-resident members of the American Pediatric Surgical Association (APSA) were surveyed in October 2020. Respondents were stratified based on self-reported thyroid surgical experience. Those who performed thyroid surgery were asked about surgical technique and operative practices; those who did not were asked about referral patterns. All respondents were asked about perceptions surrounding the volume-outcome relationship for pediatric thyroid surgery.Among 1015 APSA members, 405 (40%) responded, with 79% (317/400) practicing at academic hospitals, 58% (232/401) practicing in major metropolitan area, and 41% (161/392) with over 10 years of attending pediatric surgery experience. Most respondents (88%, n = 356) agreed that thyroid surgery volume affects outcome, though wide variation was reported in the annual case threshold for "high volume" surgery. Eighty-four respondents (21%) reported performing ≥ 1 pediatric thyroid surgery in the past year. Of these, 82% routinely use recurrent laryngeal nerve monitoring, 32% routinely send hemithyroidectomy patients home the same day, and there was little consensus surrounding postoperative hypocalcemia management. The majority of respondents endorse performing thyroid procedures with a colleague.Pediatric thyroid surgery appears to be performed by a subset of active pediatric surgeons, most of whom endorse the use of a dual operating team. More evidence is needed to build consensus around additional perioperative practices.

Objective : To evaluate, by means of cone beam computed tomography (CBCT), the volume change of maxillary sinuses in patients that underwent orthodontic maxillary posterior en masse intrusion anchored with miniplates. Materials and Methods : The sample consisted of pretreatment (T1) and posttreatment (T2) CBCT scans obtained from 14 patients (4 male and 10 female), with a mean age of 32.4 years, that underwent orthodontic maxillary posterior en masse intrusion anchored with miniplates in the zygomatic crest. The mean treatment duration was 20 months and the mean intrusion movement was 2.4 mm. Maxillary sinus volume was measured by means of the software ITK SNAP (version 3.8.0) in T1 and T2 CBCT scans. The changes in sinuses volume were calculated by T1-T2 values. Data were analyzed statistically with Wilcoxon test at 5% of level of significance and the method error was analyzed with Wilcoxon test, intraclass correlation and Dahlberg's formula. Results : The mean difference (T1-T2) was -242.85 mm³ (p = 0.396) for the right sinus and -32.5 mm³ (p = 0.875) for the left sinus. A slight increase in the volume of the sinuses was shown although these results were not statistically significant. Conclusion : The orthodontic maxillary posterior en masse intrusion anchored with miniplates did not influence significantly the maxillary sinus volume.

In this paper, a new data augmentation algorithm, named Mask2Defect is proposed. Via prior knowledge based data infusing, this method is able to generate defects with varied features. Large volume of defects with different shapes, severities, scales, rotation angles, spatial locations, and part numbers can be generated in a controllable manner. These generated defects will work as teacher samples to fine-tune the inspection model, and automatically adapt it to a wider range of defects. To be specific, we first encode the prior knowledge into the teacher mask via the Industrial Prior Knowledge Encoder, and render the defect details according to the mask with the Mask-to-Defect Construction Network. Then, the Fake-to-Real Domain Transformation GAN is used to transform the rendered samples from the fake domain into the real defect domain. Experiments reveal that the synthesized image quality of our method outperforms the state-of-the-art generative methods, and the performance of the inspection model in defect classification and localization has also been improved by fine-tuned with the generated samples.

BACKGROUND: Addressing intensity inhomogeneity is critical in magnetic resonance imaging (MRI) because associated errors can adversely affect post-processing and quantitative analysis of images (i.e., segmentation, registration, etc.), as well as the accuracy of clinical diagnosis. Although several prior methods have been proposed to eliminate or correct intensity inhomogeneity, some significant disadvantages have remained, including alteration of tissue contrast, poor reliability and robustness of algorithms, and prolonged acquisition time. OBJECTIVE: In this study, we propose an intensity inhomogeneity correction method based on volume and surface coils simultaneous reception (VSSR). METHODS: The VSSR method comprises of two major steps: 1) simultaneous image acquisition from both volume and surface coils and 2) denoising of volume coil images and polynomial surface fitting of bias field. Extensive in vivo experiments were performed considering various anatomical structures, acquisition sequences, imaging resolutions, and orientations. In terms of correction performance, the proposed VSSR method was comparatively evaluated against several popular methods, including multiplicative intrinsic component optimization and improved nonparametric nonuniform intensity normalization bias correction methods. RESULTS: Experimental results show that VSSR is more robust and reliable and does not require prolonged acquisition time with the volume coil. CONCLUSION: The VSSR may be considered suitable for general implementation.

Due to the huge volume of point cloud data, storing and transmitting it is currently difficult and expensive in autonomous driving. Learning from the high-efficiency video coding (HEVC) framework, we propose a novel compression scheme for large-scale point cloud sequences, in which several techniques have been developed to remove the spatial and temporal redundancy. The proposed strategy consists mainly of three parts: intracoding, intercoding, and residual data coding. For intracoding, inspired by the depth modeling modes (DMMs), in 3-D HEVC (3-D-HEVC), a cluster-based prediction method is proposed to remove the spatial redundancy. For intercoding, a point cloud registration algorithm is utilized to transform two adjacent point clouds into the same coordinate system. By calculating the residual map of their corresponding depth image, the temporal redundancy can be removed. Finally, the residual data are compressed either by lossless or lossy methods. Our approach can deal with multiple types of point cloud data, from simple to more complex. The lossless method can compress the point cloud data to 3.63% of its original size by intracoding and 2.99% by intercoding without distance distortion. Experiments on the KITTI dataset also demonstrate that our method yields better performance compared with recent well-known methods.