Modeling of micro-perforated panels in a complex vibro-acoustic environment using patch transfer function approach

A micro-perforated panel (MPP) with a backing cavity is a well known device for efficient noise absorption. This configuration has been thoroughly studied in the experimental conditions of an acoustic tube (Kundt tube), in which the MPP is excited by a normal incident plane wave in one dimension. In a more practical situation, the efficiency of MPP may be influenced by the vibro-acoustic behavior of the surrounding systems as well as excitation. To deal with this problem, a vibro-acoustic formulation based on the patch transfer functions (PTF) approach is proposed to model the behavior of a micro-perforated structure in a complex vibro-acoustic environment. PTF is a substructuring approach, which allows assembling different vibro-acoustic subsystems through coupled surfaces. Upon casting micro-perforations and the flexibility of the MPP under transfer function framework, the proposed PTF formulation provides explicit representation of the coupling between subsystems and facilitates physical interpretation. As an illustration example, application to a MPP with a backing cavity located in an infinite baffle is demonstrated. The proposed PTF formulation is finally validated through comparison with experimental measurements available in the literature.

Correlation between the band gap, elastic modulus, Raman shift and melting point of CdS, ZnS, and CdSe semiconductors and their size dependency

With structural miniaturization down to the nanoscale, the detectable quantities of solid materials no longer remain constant but become tunable. For the II-VI semiconductors example, the band gap expands, the elastic modulus increases, the melting point drops, and the Raman optical phonons experience red shift associated with creation of low frequency Raman acoustic modes that undergo blue shift with decreasing the dimensional scale. In order to understand the common origin of the size dependency of these seemingly irrelevant properties, we formulated these quantities for CdS, ZnS, and CdSe semiconductors from the perspectives of bond order-length-strength correlation and the local bond averaging approach. Consistency between the theory predictions and the measured size dependence of these quantities clarified that the undercoordination-induced local strain and quantum entrapment and the varied fraction of undercoordinated atoms of the entire solid correlate these quantities and dominate their size effect.

A 10-year retrospective study of primary hyperparathyroidism in children

OBJECTIVE

Primary hyperparathyroidism (PHPT) in children is thought to be extremely rare. The exact incidence is unknown and little is known of the characteristics of the disease. We reviewed our experience with PHPT to better characterize these patients.

METHODS

We carried out a retrospective study in 12 patients (age 9-16 years) who had surgical treatment between 2001 and 2011 in a single institution.

RESULTS

There were 5 male subjects and 7 female subjects. The diagnosis of PHPT in pediatric patients is frequently delayed with an average time of 41 months. The main signs of PHPT were urinary and bone disorders, as well as non-specific signs. All patients had preoperative localization studies prior to operation. Combined using of neck sonography, MIBI-scintigraphy and CT and/or MRI, our patients had a positive predictive value of 100%. After operation, all patients were confirmed to have parathyroid adenoma. 1 patient had 2 adenomas, 1 of which was an ectopic adenoma located in the mediastinum. 9 patients experienced symptomatic hypocalcemia postoperatively. No patients had any serious long-term effects from parathyroidectomy at our institution. All patients were cured after removal of the parathyroid adenoma. No permanent complication was observed for all patients.

CONCLUSION

PHPT in children is rare, the commonest signs are urinary and bone tissue impairment, as well as non-specific signs. Evaluation of serum calcium and PTH levels is diagnostic in suspected patients. Preoperative localization is essential. Surgery is without significant complications. Surgical treatment of PHPT is curative and definitive.

Tissue distribution study of naringin in rats by liquid chromatography-tandem mass spectrometry

Naringin (CAS 10236-47-2), a flavanone glucoside widely present in fruits of citrus plants, has received extensive studies on its potential effects on health benefits and was recently demonstrated to be a putative antitussive. In this study, we determined the tissue distributions of naringin and its metabolites (naringenin and naringenin's conjugates) in rats to examine whether they undergo selective uptake by specific organs. Naringin was administered orally to rats at the dose of 42 mg/kg and the concentrations of naringin and its metabolites in tissue compartments were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The areas under curve values in the individual tissues decreased as follows: stomach, small intestine, liver, trachea, muscle, kidney, lung, fat, heart, spleen, ovary, testis, brain for naringin; and liver, stomach, small intestine, kidney, trachea, lung, testis, heart, ovary, fat, spleen, muscle, brain for total naringenin (including free and its conjugates). Naringin and total naringenin were rapidly and widely distributed to all the tissues except brain in rats. They had difficulties in crossing the blood-brain barrier. There are no accumulations in rats. This study identifying naringin in several organs including lung and trachea may explain its effects as antitussive.

OT1-02-12: Early Detection of Cardiotoxicity by Advanced Cardiac Imaging and a Novel Biomarker in Breast Cancer Patients Undergoing Chemotherapy

Background The survival rate of breast cancer patients has increased due to improvements in cancer treatment. However, many survivors develop irreversible or reversible cardiotoxicity associated with anthracycline or trastuzumab therapy, respectively. To detect cardiac damage, the currently accepted method is to measure left ventricular ejection fraction (LVEF) by echocardiography, which lacks the sensitivity to predict early cardiac dysfunction.

Early identification of cardiotoxicity is essential to cancer survivors, as development of cardiomyopathy carries a worse outcome independent of cancer prognosis. Currently, there are no accepted guidelines for the early detection of myocardial injury. The use of cardiac biomarkers and more sensitive echocardiographic techniques have expanded options for monitoring, but have yet to reach a consensus.

Hence, our study will evaluate the potential predictive value of novel cardiac biomarkers and advanced echocardiographic and cardiac magnetic resonance imaging (CMR) techniques to detect subclinical myocardial damage. Our findings may be applicable for monitoring new antineoplastic agents during food and drug administration (FDA) clinical trials.

Trial Design Prospective cohort study with internal control of 20 patients newly diagnosed with breast cancer. The trial will assess endpoints at baseline, 2 weeks after initiation of therapy, and 2 weeks and 6 months after chemotherapy completion.

1. Primary Endpoint

a. Decline in left ventricular ejection fraction assessed by CMR and 3D-echo not detected by conventional methods

b. Presence of either myocardial fibrosis or edema detected by CMR

c. Changes in myocardial deformation detected by echo or CMR strain

d. Increase in cardiac biomarkers (Serum caspase-3 p17 peptide, Troponin I, B-type natriuretic peptide) and possible correlation with imaging parameters

2. Secondary Endpoint

a. Development New York Heart Association class 1 to 4 symptoms

b. Decrease in LVEF of ≥5% to ≤50% with or without symptoms

Eligibility Criteria

Inclusion Criteria:

1. Newly diagnosed stage I, II, or III breast cancer

2. Age between 18 and 75 years old.

3. Treatment with trastuzumab or anthracycline-based chemotherapy

Exclusion Criteria:

1. History of cardiovascular disease

2. Pacemaker

3. History of mediastinal radiotherapy

4. Creatinine clearance <30 ml/min

5. Serum bilirubin >2.0 mg/dl, ALT and AST > 100 U/1)

6. Hypertension, uncontrolled >140/90

7. LVEF <55% per 2-D echocardiogram

8. Claustrophobia

Specific Aims

1. Detect early myocardial injury.

2. Evaluate early predictors of left ventricular dysfunction.

3. Evaluate timing of monitoring during or post treatment

Statistical Method

This is a pilot study and 20 patients are required to reach statistical significance with 85% power. All values will be analyzed as mean±SD or n (%). Categorical indicators will be analyzed using nonparametric statistics such as Cochran's Q. Changes in imaging and biomarker parameters will be assessed using analysis of variance, while correlation between the two will be assessed using mixed models appropriate for binary outcome. Significance will be accepted at p ≤0.05 for all tests.

Present accrual and target accrual

Nine subjects are enrolled with a goal of 20.

Contact for people interested in trial:

1. Dr. Erick Avelar, eavelar@uchc.edu

2. Dr. Susan Tannenbaum, stannenbaum@uchc.edu

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT1-02-12.

Sources and implications of resonant mode splitting in silicon nanowire devices

This work investigates the effects of asymmetric cross-sectional geometry on the resonant response of silicon nanowires. The work demonstrates that dimensional variances of less than 2% qualitatively alter a nanosystem's near-resonant response, yielding a non-Lorentzian frequency response structure, which is a direct consequence of resonant mode splitting. Experimental results show that this effect is independent of device boundary conditions, and can be easily modeled using continuous beam theory. Proper understanding of this phenomenon is believed to be essential in the characterization of the dynamic response of resonant nanowire systems, and thus the predictive design of such devices.