Highly Sensitive Detection of Microstructure Variation Using a Thickness Resonant Transducer and Pulse-Echo Third Harmonic Generation.

In nonlinear ultrasound testing, the relative nonlinear parameter is conveniently measured as a sensitive means of detecting and imaging overall variation of microstructures and damages. Compared to the quadratic nonlinear parameter (ß'), the cubic nonlinear parameter (γ'), calculated as the third harmonic amplitude divided by the cube of the fundamental amplitude, has generally a higher value, providing better sensitivity in nonlinear parameter mapping. Since the third harmonic amplitude is about two orders of magnitude lower than the fundamental amplitude, efficient excitation and highly sensitive reception of third harmonic is very important. In this paper, we explore an odd harmonic thickness resonant transducer that meets the requirements for pulse-echo third harmonic generation (THG) measurements. We also address the problem of source nonlinearity that may be present in the measured amplitude of the third harmonic and propose a method to properly correct it. First, we measure γ' for a series of aluminum specimens using the through-transmission method to observe the behavior of γ' as a function of specimen thickness and input voltage, and examine the effects of various corrections such as attenuation, diffraction and source nonlinearity. Next, we apply the odd harmonic resonant transducer to pulse-echo THG measurements of precipitation heat-treated specimens. It is shown that such transducer is very effective in generation and detection of fundamental and third harmonics under finite amplitude toneburst excitation. The highly sensitive detectability of γ' are presented as a function of aging time, and the sensitivity of γ' is compared with that of ß' and ß'2.

Measurement and In-Depth Analysis of Higher Harmonic Generation in Aluminum Alloys with Consideration of Source Nonlinearity.

Harmonic generation measurement is recognized as a promising tool for inspecting material state or micro-damage and is an ongoing research topic. Second harmonic generation is most frequently employed and provides the quadratic nonlinearity parameter (ß) that is calculated by the measurement of fundamental and second harmonic amplitudes. The cubic nonlinearity parameter (ß2), which dominates the third harmonic amplitude and is obtained by third harmonic generation, is often used as a more sensitive parameter in many applications. This paper presents a detailed procedure for determining the correct ß2 of ductile polycrystalline metal samples such as aluminum alloys when there exists source nonlinearity. The procedure includes receiver calibration, diffraction, and attenuation correction and, more importantly, source nonlinearity correction for third harmonic amplitudes. The effect of these corrections on the measurement of ß2 is presented for aluminum specimens of various thicknesses at various input power levels. By correcting the source nonlinearity of the third harmonic and further verifying the approximate relationship between the cubic nonlinearity parameter and the square of the quadratic nonlinearity parameter (ß∗ß), ß2≈ß∗ß, the cubic nonlinearity parameters could be accurately determined even with thinner samples and lower input voltages.

Scarred scalp reconstruction with a rectangular expander.

Scalp reconstruction is challenging because the scalp is inelastic, stiff, and has hair follicles. Tissue expansion offers aesthetically pleasing outcomes with minimal donor-site morbidity. However, in a scarred scalp, the extent of possible dissection for the expander insertion may be limited and surgeons must make use of the limited scalp tissue. We successfully reconstructed scarred scalps using rectangular expanders. This report presents two cases: a 4× 3 cm chronic defect with widespread scarring and osteomyelitis and an 11× 7.5 cm scar tissue following a skin graft. Tissue expanders were inserted in the subgaleal plane and were inflated by 195 mL and 400 mL over periods of 2 and 3 months, respectively. Subgaleal elevation of a fasciocutaneous flap was achieved with the expanded tissue. The defects were well covered, with good color, texture, and hair-bearing tissue. There were no complications involving the tissue expanders. Rectangular expanders yield more available tissue than round or crescent-shaped expanders. Moreover, since the base of the flap is well defined, the expander can be easily inserted in a limited space. Therefore, rectangular expanders are recommended for the reconstruction of scarred scalps.

Minimally Invasive Method for Correcting Reducible Cryptotia.

Various surgical methods have been used to treat cryptotia; however, there is a drawback of these methods in that they leave a permanent scar. The authors describe a 7-year-old child who missed the optimal corrective time for cryptotia. Minimally invasive surgery was planned as a 3rd alternative to external splinting or invasive surgery by taking advantage of 2 methods. Silly putty was prefabricated as an auricular sulcus retainer, and fixation sutures between the deep dermis and temporal fascia were placed through small incisions along the future auricular sulcus. Then the prefabricated auricular sulcus retainer was maintained for 2 months. After 6 months, the corrected ear shape remained stable with the inconspicuous scar. With minimally invasive correction, a successful treatment effect can be expected while minimizing scarring in patients who are not expected to have a therapeutic effect with a simple reduction.

Surgical Site Infection Caused by Mycobacterium Septicum Following Blepharoplasty.

BACKGROUND: M fortuitum and M chelonae are commonly reported in surgical site infections caused by nontuberculous mycobacterium, but M septicum is rarely known. Herein, the authors report the first case of surgical site infection caused by M septicum in an immunocompetent patient after blepharoplasty. METHODS: A 37-year-old woman had persisting bilateral masses on the upper eyelids at 3 months after a blepharoplasty. The excision and revision were performed in a local clinic with the administration of the empirical antibiotic (clarithromycin) for 2 months, but the masses recurred. The patient was referred to the authors' hospital after the steroid was injected. As the right eyelid skin was very thin with the pus pocket, curettage was performed, while the mass on the left eyelid was completely excised. A bacterial, Acid Fast Bacilli culture with antibiotic susceptibility testing, and a DNA-polymerase chain reaction test were performed. RESULTS: The polymerase chain reaction test identified M septicum. The antibiotic treatment was delayed to identify the susceptibility to antibiotics, but the Acid Fast Bacilli culture result showed no growth. In the meantime, the mass on the right eyelid recurred. Levofloxacin and clarithromycin were administered for 6 months in consultation with the Division of Infectious Diseases. Then the mass was excised. There was no recurrence after 1 year of follow-up. CONCLUSION: There are a few reports of M septicum catheter-related infection and pulmonary disease, but surgical site infection has not been reported. When a localized mass on a surgical site is found, surgeons should consider M septicum infection and find out the pathogen with its antibiotics susceptibility.

Application of Fresnel Zone Plate Focused Beam to Optimized Sensor Design for Pulse-Echo Harmonic Generation Measurements.

In nonlinear acoustic measurements involving reflection from the stress-free boundary, the pulse-echo method could not be used because such a boundary is known to destructively change the second harmonic generation (SHG) process. The use of a focusing acoustic beam, however, can improve SHG after reflection from the specimen boundary, and nonlinear pulse-echo methods can be implemented as a practical means of measuring the acoustic nonlinear parameter (ß) of solid specimens. This paper investigates the optimal sensor design for pulse-echo SHG and ß measurements using Fresnel zone plate (FZP) focused beams. The conceptual design of a sensor configuration uses separate transmission and reception, where a broadband receiver is located at the center and a four-element FZP transmitter is positioned outside the receiver to create a focused beam at the specified position in a solid sample. Comprehensive simulations are performed for focused beam fields analysis and to determine the optimal sensor design using various combinations of focal length, receiver size and frequency. It is shown that the optimally designed sensors for 1 cm thick aluminum can produce the second harmonic amplitude and the uncorrected nonlinear parameter corresponding to the through-transmission method. The sensitivity of the optimal sensors to the changes in the designed sound velocity is analyzed and compared between the odd- and even-type FZPs.

The Effects of Vignette Scoring on Reliability and Validity of Self-Reports.

The research presented in this article combines mathematical derivations and empirical results to investigate effects of the nonparametric anchoring vignette approach proposed by King, Murray, Salomon, and Tandon on the reliability and validity of rating data. The anchoring vignette approach aims to correct rating data for response styles to improve comparability across individuals and groups. Vignettes are used to adjust self-assessment responses on the respondent level but entail significant assumptions: They are supposed to be invariant across respondents, and the responses to vignette prompts are supposed to be without error and strictly ordered. This article shows that these assumptions are not always met and that the anchoring vignette approach leads to higher Cronbach's alpha values and increased correlations among adjusted variables regardless of whether the assumptions of the approach are met or violated. Results suggest that the underlying assumptions and effects of the anchoring vignette approach should be carefully examined as the increased correlations and reliability estimates can be observed even for response variables that are independent random draws and uncorrelated with any other variable.

Percutaneous Autologous Fat Injection Following 2-Layer Flap Lower Blepharoplasty for the Correction of Tear Trough Deformity.

Tear trough deformity has been an area that has received much attention in terms of esthetic improvements. Fat transposition has been commonly used for the treatment of tear trough deformity. As some patients have had minimal improvement by that method, we propose the use of fat grafting combined with open blepharoplasty to complement the sunken area, including some of anterior maxilla region, and evaluate and precisely remove the excessive tissue.Lower blepharoplasty was performed by separating the skin and muscle flap. The excessive or laxed tissue was evaluated during the procedure and resected in each flap. Fat grafting was performed after completing a lower blepharoplasty, to ensure accurate placement on the spot where the surgeon originally intended. Overcorrection is not recommended.No serious complications were reported during a period of 10 years. Only 4 patients required a secondary fat injection.Patients who require structural correction of the lower eyelid area (eg, aggressive herniated fat, excessive skin laxity, or bulky orbicularis oculi muscle) and who need complementary material to fill the lower lid area (eg, deep, wide sunken area or relative exophthalmos) are good candidates for blepharoplasty with a fat grafting procedure.

Alveolar Bone Grafting Changes the Inclination of Teeth and Affects Malocclusion in Patients With Unilateral Alveolar Cleft.

INTRODUCTION: Alveolar bone grafting not only stabilizes the alveolar arch, but also provides positive aesthetic outcomes. However, there have been no reports about the inclinations of the incisor and canine or the change in occlusion after alveolar bone grafting. Therefore, the purpose of this study is to analyze the effects of alveolar bone grafting on tooth angles and changes in occlusion in patients with a unilateral alveolar cleft, using three-dimensional computed tomography. METHODS: The authors retrospectively studied alveolar bone grafts performed in Konkuk University Medical Center between January 2008 and January 2013. A total of 40 patients with unilateral alveolar cleft were included in this study; the authors measured the changes in tooth angles and changes in anterior and molar occlusion before and after bone grafting. RESULTS: Of the 40 patients enrolled, 21 completed follow-up and had adequate computed tomography imaging studies. Ten patients who were lost during the follow-up period, and 9 with inadequate images, were excluded. The anterior occlusion increased from -2.21 to 0.19 mm (P < 0.0001) and the molar occlusion increased from 0.75 to 2.10 (P < 0.0001). The dental angle decreased from 25.23° to 15.32° (P = 0.001). DISCUSSION: Alveolar bone grafting provides support to the tooth root and changes the inclination of the tooth, resulting in changes in occlusion and positive aesthetic outcomes.