Early bearing fault analysis using high frequency enveloping techniques

High frequency acceleration enveloping is one of many tools that vibration analysts have at their disposal for the diagnosis of bearing faults in rotating machinery. This technique is believed to facilitate very early detection of potential failures by detecting low amplitude repetitive impacts in frequency ranges above conventional condition monitoring. One traditional enveloping method uses a mathematical operation known as the Hilbert transform along with other signal processing procedures such as band-pass filtering and full-wave rectification. For comparison, another method uses a proprietary algorithm included in National Instruments’ LabVIEWTM add-on package: Sound and Measurement Suite. Enveloping’s inherent problem with noise introduction is also addressed herein. A controlled, three-stage fault was induced and diagnosed utilizing both acceleration enveloping methods and traditional fast Fourier transformation (FFT) described herein. A performance assessment of the enveloping process with respect to FFT as well as the performance between individual enveloping methods is presented. In summary, several high frequency acceleration enveloping methods exist that can be effective tools in detection of bearing faults earlier than FFT alone

Joint Tenancy—Creditor-Debtor Relations

By Initiative No. 208, adopted and now codified as RCW 64.28, the former prohibition against joint tenancy with the right of survivorship has been repealed and substituted with .... a form of co-ownership of property, real and personal, known as joint tenancy. \u27 The proviso that the transfer shall not derogate from the rights of creditors raises serious questions of meaning and interpretation. If the proviso means that the rights of creditors will not be changed by joint tenancy ownership, then this article will serve little purpose. If the proviso is to be applied only to the creditors existing at the time of the creation of the joint tenancy, then all subsequent creditors must look to the common law for their rights and remedies. If the proviso applies only to the original transfer creating the joint tenancy, an existing creditor may ignore the transfer and treat the debtor as the sole owner, but if the proviso be given a broader interpretation to permit its application to the passage of title occurring at the death of a joint tenant, it will create creditors\u27 rights and incidents of joint tenancy beyond the incidents at common law.8 RCW 64.28.010 further provides, ... a joint tenancy shall have the incidents of survivorship and severability as at common law. The better approach would be to limit the proviso to the original transfer, though the matter will not be laid to rest until the supreme court has passed upon this specific point

Amiodarone-Induced Hyperthyroidism in a Patient with Functioning Papillary Carcinoma of the Thyroid and Extensive Hepatic Metastases

Thyroid hormone producing thyroid carcinoma is an uncommon cause of thyrotoxicosis. A patient with extensive hepatic metastases from well-differentiated carcinoma is presented. Administration of amiodarone for atrial fibrillation led to the development of hyperthyroidism. Precipitation of thyrotoxicosis by iodine-containing compounds in patients with thyroid carcinoma is rare. The relatively high iodine load and the slow elimination of amiodarone complicate the clinical management of such patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63161/1/thy.2005.15.1337.pd

Current Trends in Functional Imaging of Pheochromocytomas and Paragangliomas

Most pheochromocytomas/paragangliomas should be evaluated with anatomical imaging (computed tomography or magnetic resonance imaging) followed by functional imaging (nuclear medicine modalities). Functional imaging assures that the tumor is indeed a pheochromocytoma/paraganglioma and enables more thorough localization, especially detecting as many lesions as possible (in particular for metastatic disease). Functional imaging for pheochromocytomas/paragangliomas, can use radiolabled ligands specific for pathways of synthesis, metabolism, and inactivation of catecholamines or nonspecific ligands. In an overview of the available nuclear medicine modalities, we summarize the accumulated experience and recommend when functional imaging should be applied to patients with pheochromocytoma/paraganglioma.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74881/1/annals.1353.041.pd

Inhibition of Neutral Amino Acid Transport Across the Human Blood-Brain Barrier by Phenylalanine

The delivery of large neutral amino acids (LNAAs) to brain across the blood-brain barrier (BBB) is mediated by the L-type neutral amino acid transporter present in the membranes of the brain capillary endothelial cell. In experimental animals, the L-system transporter is saturated under normal conditions, and therefore an elevation in the plasma concentration of one LNAA will reduce brain uptake of others. In this study, we used positron emission tomography (PET) to determine the effect of elevated plasma phenylalanine concentrations on the uptake of an artificial neutral amino acid, [ 11 C]-aminocyclohexanecarboxylate ([ 11 C]ACHC), in human brain. PET scans were performed on six normal male subjects after an overnight fast and again 60 min after oral administration of 100 mg/kg of phenylalanine. The plasma phenylalanine concentration increased by an average of 11-fold between the first and second scans. This increase produced a reduction in [ 11 C]ACHC uptake in all brain regions but not in scalp. The mean ± SD influx rate constant for whole brain decreased after phenylalanine ingestion from 0.036 ± 0.002 to 0.019 ± 0.004 ml/g/min. Kinetic analysis of the effect of plasma phenylalanine concentration on the rate of [ 11 C]ACHC uptake is compatible with a model of competitive inhibition so that large increases in the concentration of one LNAA in plasma will reduce the brain uptake of other LNAAs across the human BBB.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65880/1/j.1471-4159.1995.64031252.x.pd

Courses of Malignant Pheochromocytoma

Survival of patients with metastatic pheochromocytoma that have exceeded 30 years without therapy to reduce tumors have been reported. We reviewed the records of 38 patients with malignant pheochromocytoma who had received 131 I-metaiodiobenzylguanidine ( 131 I-MIBG) treatments between 1981 and 1996 to evaluate longevity. Survival from diagnosis to last follow-up exceeded 5 years in 21 of 38 (55%) and ≥10 years in 50%. In 17 of 21, the interval from diagnosis to 131 I-MIBG therapy was greater than 5 years. Survival following 131 I-MIBG was ≥5 years in 12 of 17 and ≥10 years in 7 of 17 patients despite continued evidence of excessive circulating catecholamines. Objective responses to 131 I-MIBG therapy were seen in about 30% and were usually of a few years, duration, but one individual exhibited marked reductions in volume and function of tumors that have persisted for 21 years. No feature, including a remission of >5 years following surgical excision, was found to predict prolonged survival. In summary, many patients with malignant pheochromocytoma will follow a course extending over many years. The role of 131 I-MIBG therapy in longevity is uncertain, but this radiopharmaceutical reduces evidence of tumors in some patients. Criteria for selecting patients who will benefit from treatment remain to be determined.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73567/1/annals.1353.053.pd

PET imaging in pediatric oncology

High-quality PET imaging of pediatric patients is challenging and requires attention to issues commonly encountered in the practice of pediatric nuclear medicine, but uncommon to the imaging of adult patients. These include intravenous access, fasting, sedation, consent, and clearance of activity from the urinary tract. This paper discusses some technical differences involved in pediatric PET to enhance the quality of scans and assure the safety and comfort of pediatric patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46711/1/247_2003_Article_1112.pd