Tangible AR interaction based on fingertip touch using small-sized nonsquare markers

AbstractAlthough big-sized markers are good for accurate marker recognition and tracking, they are easily occluded by other objects and deteriorate natural visualization and level of immersion during user interaction in AR environments. In this paper, we propose an approach to exploiting the use of rectangular markers to support tangible AR interaction based on fingertip touch using small-sized markers. It basically adjusts the length, width, and interior area of rectangular markers to make them more suitably fit to longish objects like fingers. It also utilizes convex polygons to resolve the partial occlusion of a marker and properly enlarges the pattern area of a marker while adjusting its size without deteriorating the quality of marker detection. We obtained encouraging results from users that the approach can provide better natural visualization and higher level of immersion, and be accurate and tangible enough to support a pseudo feeling of touching virtual products with human hands or fingertips during design evaluation of digital handheld products

Size-Dependent Phase Transition Memory Switching Behavior and Low Writing Currents in GeTe Nanowires

Synthesis and device characteristics of highly scalable GeTe nanowire-based phase transition memory are reported. The authors have demonstrated reversible phase transition memory switching behavior in GeTe nanowires, and obtained critical device parameters, such as write and erase currents, threshold voltage, and programming curves. The diameter dependence of memory switching behavior in GeTe nanowires was studied and a systematic reduction of writing currents with decreasing diameter was observed, with currents as low as 0.42 mA for a 28 nm nanowire. Results show that nanowires are very promising for scalable memory applications and for studying size-dependent phase transition mechanisms at the nanoscale

A Mixed-effects Height-Diameter Model for Pinus densiflora Trees in Gangwon Province, Korea

A new mixed-effects model was developed that predicts individual-tree total height for Pinus densiflora trees in Gangwon province as a function of individual-tree diameter (cm). The mixed-effects model contains two random-effects parameters. Maximum likelihood estimation was used to fit the model to 560 height-diameter observations of individual trees measured throughout Gwangwon province in 2007 as part of the National Forest Inventory Program in Korea. The new model is an improvement over fixed effects models because it can be calibrated to a local area, such as an inventory plot or individual stand. The new model also appears to be an improvement over the Forest Resources Evaluation and Prediction Program for the ten calibration trees used in this study. An example is provided that describes how to estimate the random-effects parameters using ten calibration trees

Fabrication of a spherical inclusion phantom for validation of magnetic resonance-based magnetic susceptibility imaging

© 2019 Kim et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Fabrication of a spherical multi-compartment MRI phantom is demonstrated that can be used to validate magnetic resonance (MR)-based susceptibility imaging reconstruction. The phantom consists of a 10 cm diameter gelatin sphere that encloses multiple smaller gelatin spheres doped with different concentrations of paramagnetic contrast agents. Compared to previous multi-compartment phantoms with cylindrical geometry, the phantom provides the following benefits: (1) no compartmental barrier materials are used that can introduce signal voids and spurious phase; (2) compartmental geometry is reproducible; (3) spherical susceptibility boundaries possess a ground-truth analytical phase solution for easy experimental validation; (4) spherical geometry of the overall phantom eliminates background phase due to air-phantom boundary in any scan orientation. The susceptibility of individual compartments can be controlled independently by doping. During fabrication, formalin crosslinking and water-proof surface coating effectively blocked water diffusion between the compartments to preserve the phantom’s integrity. The spherical shapes were realized by molding the inner gel compartments in acrylic spherical shells, 3 cm in diameter, and constructing the whole phantom inside a larger acrylic shell. From gradient echo images obtained at 3T, we verified that the phantom produced phase images in agreement with the theoretical prediction. Factors that limit the agreement include: air bubbles trapped at the gel interfaces, imperfect magnet shimming, and the susceptibility of external materials such as the phantom support hardware. The phantom images were used to validate publicly available codes for quantitative susceptibility mapping. We believe that the proposed phantom can provide a useful testbed for validation of MR phase imaging and MR-based magnetic susceptibility reconstructio

Clinical Manifestations of Recurrent Parotid Pleomorphic Adenoma

Objectives. This study was undertaken to confirm the clinical characteristics of recurrent pleomorphic adenoma (RPA), and to identify those factors that affect the development of malignant transformation (MT) from RPA. Methods. The medical records of 270 patients, who were operated upon for parotid PA, were retrospectively reviewed. The pathologic specimens of a selected series of 23 patients were reviewed for histologic subtype and microscopic multi-nodularity. Results. Mean age of initial operation in RPA without MT (RPA(-MT)) group was significantly lower than that of primary PA group. Mean age of the revision operation in RPA with MT (RPA(+MT)) group was significantly greater than that of RPA(-MT) group. Mean interval from operation to recurrence shortened after each revision operation. The risk of MT and additional recurrence increased significantly with recurrence. In RPA(-MT) group tumor recurrence occurred in 21.4% of patients despite a clear resection margin. Conclusion. The risk factors for MT may be an age of over 45 yr and multiple recurrences. However, younger patients are more at risk of recurrence. A clear resection margin cannot guarantee a cure in RPA, and it seems that parotid pleomorphic adenomas slowly gain malignant characteristics after repeated recurrences.SUH MW, 2005, KOREAN J HEAD NECK O, V21, P146HANNA EY, 2005, CUMMINGS OTOLARYNGOL, P1348Ghosh S, 2003, CLIN OTOLARYNGOL, V28, P262Glas AS, 2002, CANCER, V94, P2211, DOI 10.1002/cncr.10445Glas AS, 2001, HEAD NECK-J SCI SPEC, V23, P311BRADLEY PJ, 2001, CURR OPIN OTOLARYNGO, V9, P100Carew JF, 1999, OTOLARYNG HEAD NECK, V121, P539Junquera L, 1999, HEAD NECK-J SCI SPEC, V21, P652Hancock BD, 1999, ANN ROY COLL SURG, V81, P299Bankamp DG, 1999, LARYNGO RHINO OTOL, V78, P77Hoorweg JJ, 1998, EUR J SURG ONCOL, V24, P452Henriksson G, 1998, CANCER, V82, P617Laskawi R, 1998, BRIT J ORAL MAX SURG, V36, P48Klijanienko J, 1997, HEAD NECK-J SCI SPEC, V19, P629Leverstein H, 1997, EUR ARCH OTO-RHINO-L, V254, P313SunardhiWidyaputra S, 1995, PATHOL RES PRACT, V191, P1186PHILLIPS PP, 1995, ANN OTO RHINOL LARYN, V104, P100BUCHMAN C, 1994, LARYNGOSCOPE, V104, P1231NATVIG K, 1994, HEAD NECK-J SCI SPEC, V16, P213JACKSON SR, 1993, J LARYNGOL OTOL, V107, P546MCGREGOR AD, 1988, BRIT J PLAST SURG, V41, P177FEE WE, 1978, LARYNGOSCOPE, V88, P265SEIFERT G, 1976, HNO, V24, P415NAEIM F, 1976, ARCH PATHOL LAB MED, V100, P271FRAZELL EL, 1954, CANCER, V7, P637

Mild-to-moderate functional tricuspid regurgitation in patients undergoing mitral valve surgery

ObjectiveThe decision to repair mild-to-moderate functional tricuspid regurgitation (TR) during mitral valve surgery remains controversial. We evaluated the effects of tricuspid valve (TV) repair for functional mild-to-moderate TR during mitral valve surgery.MethodsWe enrolled 959 patients with mild-to-moderate functional TR who underwent mitral valve surgery with (repair group n = 431) or without (control group n = 528) concomitant TV repair from January 1994 to September 2010.ResultsThere were no significant differences in early mortality or major morbidity rates. Median follow-up was 64.8 months (range, 0.03-203.6 months). After adjustment for baseline characteristics using a propensity score adjustment model, the repair group had similar risks for TV reoperation (hazard ratio [HR], 0.46; 95% confidence interval [CI], 0.10-2.07; P = .31); congestive heart failure (HR, 1.12; 95% CI, 0.37-3.36; P = .84); death (HR, 1.41; 95% CI, 0.82-2.42; P = .22); and the composite of death, TV reoperation, and congestive heart failure (HR, 1.24; 95% CI, 0.76-2.03; P = .39) compared with the control group. On multivariate Cox-regression analysis, old age, atrial fibrillation without a Maze procedure, diabetes mellitus, chronic renal failure, poor left ventricular ejection fraction, and redo surgery emerged as significant independent risk factors for the composite outcome of death, TV reoperation, and congestive heart failure.ConclusionsEarly or late clinical benefits of concomitant TV repair for mild-to-moderate TR during mitral valve surgery were uncertain through a long-term follow-up of 959 patients. Several preoperative factors and the performance of Maze procedure for AF seem to be more important than TV repair in overall clinical outcomes