Ultrasonic defect characterization using parametric-manifold mapping.

The aim of ultrasonic non-destructive evaluation includes the detection and characterization of defects, and an understanding of the nature of defects is essential for the assessment of structural integrity in safety critical systems. In general, the defect characterization challenge involves an estimation of defect parameters from measured data. In this paper, we explore the extent to which defects can be characterized by their ultrasonic scattering behaviour. Given a number of ultrasonic measurements, we show that characterization information can be extracted by projecting the measurement onto a parametric manifold in principal component space. We show that this manifold represents the entirety of the characterization information available from far-field harmonic ultrasound. We seek to understand the nature of this information and hence provide definitive statements on the defect characterization performance that is, in principle, extractable from typical measurement scenarios. In experiments, the characterization problem of surface-breaking cracks and the more general problem of elliptical voids are studied, and a good agreement is achieved between the actual parameter values and the characterization results. The nature of the parametric manifold enables us to explain and quantify why some defects are relatively easy to characterize, whereas others are inherently challenging.

Palliative home parenteral nutrition: Clinical service evaluation and identifying potential prognostic factors to assist with patient selection.

BACKGROUND AND AIMS: Home parenteral nutrition (HPN) for palliation has little evidence supporting existing guidance. Patient selection remains challenging. We aimed to evaluate use of palliative HPN in our service against ESPEN guidance, and to identify potential prognostic indicators. METHODS: Palliative care patients commenced on HPN were identified. Medical notes, computer records and HPN database were accessed to identify patient demographics, primary diagnosis and aetiology of intestinal failure, blood test results potentially associated with prognosis (eGFR, albumin, CRP, Hb), presence of ascites, and PN duration. By dichotomising blood results Kaplan-Meier survival plots were derived to identify potential associations with survival. RESULTS: From the HPN database of 111 patients, 20 (18%) were identified as palliative. Six were male (30%), median age (interquartile range (IQR)) 56.4 (51.5-66.8) years. Four patients commenced palliative HPN between 2000 and 2006, while 2007-2013 there were 16. The median number (IQR) of nights on HPN was 85 (19-352). The most common indication was gastro-intestinal obstruction (n = 13, 65%) and short bowel syndrome following palliative surgical resection (n = 4, 20%). Kaplan-Meier survival plots identified worse prognosis on HPN if the presenting albumin was ≤30 g/L p = 0.016. CONCLUSION: The use of HPN in palliative care is increasing. Current patient selection meets with ESPEN guidance with respect to aetiology of intestinal failure and length of survival on PN. We suggest that a low albumin (not a marker of malnutrition) may help to predict those who are likely to survive less long on palliative HPN. A multi-centre prospective study, also examining quality of life would help define improved guidance.

Tunable beam shaping with a phased array acousto-optic modulator.

We demonstrate the generation of Bessel beams using an acousto-optic array based on a liquid filled cavity surrounded by a cylindrical multi-element ultrasound transducer array. Conversion of a Gaussian laser mode into a Bessel beam with tunable order and position is shown. Also higher-order Bessel beams up to the fourth order are successfully generated with experimental results very closely matching simulations.

Ultrasonic assembly of anisotropic short fibre reinforced composites.

We report the successful manufacture of short fibre reinforced polymer composites via the process of ultrasonic assembly. An ultrasonic device is developed allowing the manufacture of thin layers of anisotropic composite material. Strands of unidirectional reinforcement are, in response to the acoustic radiation force, shown to form inside various matrix media. The technique proves suitable for both photo-initiator and temperature controlled polymerisation mechanisms. A series of glass fibre reinforced composite samples constructed in this way are subjected to tensile loading and the stress-strain response is characterised. Structural anisotropy is clearly demonstrated, together with a 43% difference in failure stress between principal directions. The average stiffnesses of samples strained along the direction of fibre reinforcement and transversely across it were 17.66±0.63MPa and 16.36±0.48MPa, respectively.

Patterning of microspheres and microbubbles in an acoustic tweezers.

We describe the construction of an ultrasonic device capable of micro-patterning a range of microscopic particles for bioengineering applications such as targeted drug delivery. The device is formed from seven ultrasonic transducers positioned around a heptagonal cavity. By exciting two or three transducers simultaneously, lines or hexagonal shapes can be formed with microspheres, emulsions and microbubbles. Furthermore, phase control of the transducers allows patterning at any desired position in a controlled manner. The paper discusses in detail direct positioning of functionalised microspheres, emulsions and microbubbles. With the advantages of miniaturization, rapid and simple fabrication, ultrasonic tweezers is a potentially useful tool in many biomedical applications.

Comparison of ultrasonic array imaging algorithms for nondestructive evaluation.

Ultrasonic array imaging algorithms have been widely used and developed in nondestructive evaluation in the last 10 years. In this paper, three imaging algorithms [total focusing method (TFM), phase-coherent imaging (PCI), and spatial compounding imaging (SCI)] are compared through both simulation and experimental measurements. In the simulation, array data sets were generated using a hybrid forward model containing a single defect among a multitude of randomly distributed point scatterers to represent backscatter from material microstructure. The number of point scatterers per unit area and their scattering amplitude were optimized to reduce computation cost. The SNR of the final images and their resolution were used to indicate the quality of the different imaging algorithms. The images of different types of defects (point reflectors and planar cracks) were used to investigate the robustness of the imaging algorithms. It is shown that PCI can yield higher image resolution and higher SNR for defects in material with weak backscatter than TFM, but that the images of cracks are distorted. Overall, TFM is the most robust algorithm across a range of different types of defects. It is also shown that the detection limit of all three imaging algorithms is almost equal for weakly scattering defects.

Acoustic radiation force analysis using finite difference time domain method.

Acoustic radiation force exerted by standing waves on particles is analyzed using a finite difference time domain Lagrangian method. This method allows the acoustic radiation force to be obtained directly from the solution of nonlinear fluid equations, without any assumptions on size or geometry of the particles, boundary conditions, or acoustic field amplitude. The model converges to analytical results in the limit of small particle radii and low field amplitudes, where assumptions within the analytical models apply. Good agreement with analytical and numerical models based on solutions of linear scattering problems is observed for compressible particles, whereas some disagreement is detected when the compressibility of the particles decreases.

Impact of bone turnover markers and/or educational information on persistence to oral bisphosphonate therapy: a community setting-based trial.

UNLABELLED: We examined how the use of bone turnover markers and educational information affects persistence of bisphosphonate use in osteoporotic patients. We found that reporting bone turnover results and/or educational information did not affect persistence. INTRODUCTION: Long-term adherence and persistence to osteoporosis medication are poor. We examined whether reporting of bone turnover marker results, education about osteoporosis, or a combination of both would increase persistence to oral bisphosphonates. METHODS: Two hundred and forty women who were 5 years postmenopausal with BMD at least 2.0 standard deviations below normal were recruited for the study. All women were given a new prescription for alendronate and randomly assigned to one of four groups: (1) bone marker results at baseline, 3 and 12 months; (2) educational materials every month and a membership in the National Osteoporosis Foundation; (3) bone marker and educational information; and (4) control, no information other than usual care. Persistence among randomization groups was tested using survival analysis adjusting for the delay between intervention methods. RESULTS: Of those filling their initial prescription, 95.5% refilled their prescription at the end of the first month, 87% at 3 months, 82% at 6 months, and 78% at 10 months. Overall persistence through 12 months was 54%. There was no difference found among the four groups for persistence time using (p > 0.58). CONCLUSION: Providing bone turnover marker results is not an effective way to enhance early compliance and persistence with drug therapy. While the women in our study felt that bone marker results and educational information were helpful to them, there was no difference in persistence between those who received either bone marker information and/or educational information and those who did not. Because of the unexpected rate of primary nonadherence, this study may be underpowered.

Manipulation of microparticles using phase-controllable ultrasonic standing waves.

A method of manipulating microparticles in a liquid using ultrasound is proposed and demonstrated. An ultrasonic standing wave with nodal planes whose positions are controllable by varying the relative phase of two applied sinusoidal signals is generated using a pair of acoustically matched piezoelectric transducers. The resulting acoustic radiation force is used to trap micron scale particles at a series of arbitrary positions (determined by the relative phase) and then move them in a controlled manner. This method is demonstrated experimentally and 5 µm polystyrene particles are trapped and moved in one dimension through 140 µm.

The detectability of kissing bonds in adhesive joints using ultrasonic techniques.

This paper concerns a study of the detectability of dry contact kissing bonds in adhesive joints using three ultrasonic inspection techniques. Conventional normal incidence longitudinal and shear wave inspection were conducted on dry contact kissing bonds using a standard damped ultrasonic transducer and an electro-magnetic acoustic transducer (EMAT) respectively. The detectability of the dry contact kissing bonds was assessed by calculating the reflection coefficient of the imperfect interface at varying loads for a number of surface roughnesses. A high power ultrasonic method was also employed to determine the non-linear behavior of the adhesive interface. The non-linearity of the interface was determined by the ratio of the amplitudes of the first harmonic and fundamental frequencies of the transmitted waveform. It was found that the high power technique showed the greatest sensitivity to these kissing bonds at low contact pressures, however at high loads conventional longitudinal wave testing was more sensitive. It was also noted that a combination of two or more techniques could provide enhanced information about the kissing bond compared to a single technique alone.

Excretion of sweat and urine pyridinoline crosslinks in healthy controls and subjects with established metabolic bone disease.

Convenient techniques for measuring rates of bone turnover have been developed in recent years with the advent of biochemical markers of bone metabolism. One recent of these techniques is a collection method and quantitative enzyme immunoassay for free pyridinoline crosslinks in human sweat. The concentrations of pyridinoline crosslinks in 5-day sweat collections and first morning void and 24-hour urine collections from healthy subjects and subjects with established metabolic bone disorders were determined. T-scores were higher in the sweat system than in the urine system by up to 10-fold in postmenopausal subjects, women with hyperparathyroidism, and subjects with postmenopausal osteoporosis. For subjects with postmenopausal osteoporosis, receiver-operating characteristic curve analysis yielded areas under the curve of 0.699, 0.629, and 0.520 for sweat pyridinoline, first morning void urine pyridinoline, and 24 hour urine pyridinoline respectively. The areas under the curve of the sweat and first morning void urine measurements were significantly greater (p<0.05) than the 24-hour pyridinoline measurements. Healthy postmenopausal subjects and subjects with postmenopausal osteoporosis were monitored before and during estrogen replacement therapy or alendronate therapy. Sweat pyridinoline values declined by 49.0 +/- 12.4% and 19.4 +/- 19.9% for estrogen and alendronate subjects respectively. We conclude that this non-invasive technique is a sensitive and specific measure of bone resorption and is appropriate as an adjunct to techniques such as bone density and may also be useful in monitoring of response to anti-resorptive therapies.

Recurrent severe infantile cortical hyperostosis (Caffey disease) in siblings.

Infantile cortical hyperostosis (ICH), Caffey disease, is a multifocal, inflammatory skeletal process with classic onset before the fifth month of life and resolution by the age of 3 years. A severe phenotype with early prenatal onset has also been described. Inheritance is generally accepted a autosomal dominant with variable expression and penetrance. However, occurrence in siblings with no family history has been reported, raising the possibility of heterogeneity and the existence of a severe autosomal recessive form. We describe a third family with prenatally diagnosed ICH in two siblings, providing further evidence for this form of inheritance.

American College of Sports Medicine position stand. The Female Athlete Triad.

The Female Athlete Triad is a syndrome occurring in physically active girls and women. Its interrelated components are disordered eating, amenorrhea, and osteoporosis. Pressure placed on young women to achieve or maintain unrealistically low body weight underlies development of the Triad. Adolescents and women training in sports in which low body weight is emphasized for athletic activity or appearance are at greatest risk. Girls and women with one component of the Triad should be screened for the others. Alone or in combination, Female Athlete Triad disorders can decrease physical performance and cause morbidity and mortality. More research is needed on its causes, prevalence, treatment, and consequences. All individuals working with physically active girls and women should be educated about the Female Athlete Triad and develop plans to prevent, recognize, treat, and reduce its risks.

Effect of bone density information on decisions about hormone replacement therapy: a randomized trial.

OBJECTIVE: To determine the effect of bone density information on a woman's decision about hormone replacement therapy (HRT). METHODS: One hundred forty women were assigned randomly to receive either educational information about osteoporosis and a voucher for a bone mineral density test 12 months later or the same educational information plus an immediate dual-energy x-ray absorptiometry test for bone mineral density. Women in both groups were offered prescription for HRT. RESULTS: Of the 93 women who received a bone mineral density test, 63.4% elected HRT and filled their prescription, compared with only 20.0% of the 43 women who did not have a bone mineral density test (P < .01). Women who were classified as osteopenic (between -1 and -2.5 standard deviations [SDs] of the young normal bone mineral density) or osteoporotic (more than 2.5 SDs below young normals) were more likely to choose HRT (69.4%) than were women whose bone mineral density was in the normal range (51.6%) (above -1 SD of the young normal bone mineral density value). CONCLUSIONS: A bone mineral density test, regardless of the result, had a significant effect on women's decisions to accept HRT. Within the group having the test, women with lower bone mineral density were more likely to choose HRT.

Hormone replacement therapy in postmenopausal women: urinary N-telopeptide of type I collagen monitors therapeutic effect and predicts response of bone mineral density.

PURPOSE: To assess the ability of the urinary N-telopeptide of type I collagen (NTx) to monitor and predict therapeutic effects of hormone replacement therapy (HRT) in postmenopausal women. PATIENTS AND METHODS: To assess the relationship between baseline or change in NTx (predictive variable), and change in lumbar and hip bone mineral density (BMD; outcome variable), we conducted a 2-year randomized controlled study at academic university and private practice medical centers in 236 healthy women 1 to 3 years postmenopausal; 227 women completed the study. Women received estrogen plus progesterone plus calcium (treated group) or calcium alone (control group). RESULTS: In the treated group NTx significantly (P < 0.0001) decreased, and spine and hip BMD significantly (P < 0.00001 and P < 0.005, respectively) increased; in the control group NTx did not change but BMD decreased significantly (P < 0.01). Subjects in the highest quartiles for baseline NTx (67 to 188 units) or decreasing NTx (-66% to -87%) through 6 months demonstrated the greatest gain in BMD in response to HRT (P < 0.05 and P < 0.005). For every increase of 30 units in baseline NTx the odds of gain in BMD in response to HRT increased by a factor of 5.0 (95% confidence interval [CI] 1.9 to 13.3); for every 30% decrease in NTx through 6 months, the odds of gaining BMD in response to HRT increased by a factor of 2.6 (95% CI 1.6 to 4.4). In the control group an increase of 30 units in mean NTx across the study indicated a higher odds of losing BMD by a factor of 3.2 (95% CI 1.6 to 6.5). A high baseline NTx (> 67 units) indicated a 17.3 times higher risk of BMD loss if not treated with HRT. CONCLUSION: These data support the clinical utility of NTx to monitor the antiresorptive effect of HRT in recently postmenopausal women, and to predict changes in BMD in response to HRT.

Irreversible bone loss in former amenorrheic athletes.

Small gains in bone mineral density (BMD) have been reported in the first year following resumption of menses in amenorrheic athletes but there have been no long-term outcome studies. The purpose of this study was to determine whether the BMD of former oligomenorrheic or amenorrheic athletes normalizes following several years of normal menses or use of oral contraceptives. Twenty-nine athletes first studied in this laboratory 8.1 years (range 6-10 years) ago were available for follow-up. At recruitment (time 1) 29 athletes, mean age of 30.6 years, were non-smokers, exercised 4 or more days/week for at least 45 min, had not used oral contraceptives, and had no medical conditions affecting bone metabolism. At time 1, 9 women (R/R) had always menstruated regularly, 9 (R/O/A) had experienced intermittent oligo/amenorrhea as well as regular menses, and 11 (O/A) had never menstruated regularly. At follow-up (time 2) mean age of the women was 38.2 years and there were no significant changes in height, weight or activity patterns. BMD (g/cm2) was measured at the lumbar vertebrae (L1-4 and femoral neck by dual-energy X-ray absorptiometry and expressed as a percentage of R/R values. Vertebral BMD was significantly lower in the O/A group compared with the R/R group at both time 1 and time 2 (p < 0.05). The R/O/A group had intermediate values and did not differ significantly from R/R or O/A at either time. Differences in technique between machines for determining femoral neck BMD made it difficult to detect the longitudinal effect of menstrual status at that site. Despite several years of normal menses or use of oral contraceptives, the mean vertebral BMD of former oligo-amenorrheic athletes remained low, being 84.4% of the R/R value compared to 84.8% at time 1. Those experiencing menstrual regularity with intermittent oligo/amenorrhea remained at an intermediate position of 94.7% of the R/R mean. Our results suggest early intervention is necessary to prevent irreversible vertebral bone loss in oligo/amenorrheic athletes.

Bone density at multiple skeletal sites in amenorrheic athletes.

OBJECTIVE: To determine if there is a generalized loss of bone mass at multiple skeletal sites in amenorrheic athletes compared with a group of eumenorrheic athletes. DESIGN: A case-control study examining the differences in bone mineral density (BMD) between amenorrheic and eumenorrheic athletes. SETTING: Seattle, Wash, and surrounding communities. PARTICIPANTS: Forty-nine athletes, aged 17 to 39 years, were selected from those responding to advertisements in local sporting-goods stores and a track-and-field newsletter. Athletes were defined as amenorrheic if they had had fewer than 2 menstrual cycles in the last 12 months or none in the past 6 months, or eumenorrheic if they had had 10 to 13 cycles in the previous year. Only women who met these criteria, confirmed by tests for estradiol and progesterone levels, were enrolled in the study. MAIN OUTCOME MEASURES: Bone mineral density measured by dual-energy x-ray absorptiometry. RESULTS: Amenorrheic athletes had significantly lower BMD (P < .01) at the lumbar spine, femoral neck, trochanter, Ward triangle, intertrochanteric region, femoral shaft, and tibia. No difference was noted at the fibula. Body weight combined with months of amenorrhea and age of menarche predicted the BMD of the lumbar spine for amenorrheic athletes. Duration of amenorrhea and body weight of amenorrheic athletes predicted BMD at the femoral neck, trochanter, intertrochanteric region, and tibia. Weight alone predicted BMD at the femoral shaft and tibia. Age plus weight predicted lumbar BMD of eumenorrheic women. CONCLUSION: Extended periods of amenorrhea may result in low bone density at multiple skeletal sites including those subjected to impact loading during exercise.

Physical activity, nutrition, and chronic disease.

Epidemiologic, animal, clinical, and metabolic studies demonstrate the independent roles of physical activity and nutrition in the prevention and treatment of several chronic diseases. Fewer data are available to describe the synergistic effects of exercise and diet, and questions remain as to whether and how these two lifestyle factors work together to promote health and prevent disease. This paper briefly reviews many of the known effects of physical activity and nutrition on the prevention and treatment of coronary heart disease, non-insulin-dependent diabetes mellitus, obesity, and osteoporosis as well as how exercise and diet may work together. A discussion of how to increase physical activity levels and how to improve dietary intake also is included. Finally, current exercise and dietary recommendations are summarized, as are directions for future research.