UTILIZATION OF SPECTRAL VELOCITY OF FLEXURAL WAVES TO DETECT LOOSE SLEEPERS

The identification of a loose sleeper is important for the operation and safety of a railway system because the excessive movement of a loose railway sleeper can cause derailment and passenger discomfort. There are available methods on how to detect a loose sleeper, such as: 1) a method using a conventional approach based on human judgement and experience, which is not advisable if the researcher is a beginner; 2) Fixed Post method, wherein a fixed post with displacement sensor is installed in a ballast, which is not reliable because vibration of a sleeper during train passage might affect the results from this test; and 3) Non-Destructive Testing (NDT) methods, which include the use of Light Falling Weight Deflectometer (LFWD) and line scan camera, both of which are, however, expensive to use for a routine testing technique. In this paper, Finite Element Analysis (FEA) was performed to set the criteria for the loose sleepers. Impulse Response (IR) Method was used on an actual site. The spectral velocity of flexural waves and mobility function from the impulse response test were proposed to investigate the quality of a railway sleeper

Design of exceptionally strong and conductive Cu alloys beyond the conventional speculation via the interfacial energy-controlled dispersion of gamma-Al2O3 nanoparticles

The development of Cu-based alloys with high-mechanical properties (strength, ductility) and electrical conductivity plays a key role over a wide range of industrial applications. Successful design of the materials, however, has been rare due to the improvement of mutually exclusive properties as conventionally speculated. In this paper, we demonstrate that these contradictory material properties can be improved simultaneously if the interfacial energies of heterogeneous interfaces are carefully controlled. We uniformly disperse γ-Al2O3 nanoparticles over Cu matrix, and then we controlled atomic level morphology of the interface γ-Al2O3 //Cu by adding Ti solutes. It is shown that the Ti dramatically drives the interfacial phase transformation from very irregular to homogeneous spherical morphologies resulting in substantial enhancement of the mechanical property of Cu matrix. Furthermore, the Ti removes impurities (O and Al) in the Cu matrix by forming oxides leading to recovery of the electrical conductivity of pure Cu. We validate experimental results using TEM and EDX combined with first-principles density functional theory (DFT) calculations, which all consistently poise that our materials are suitable for industrial applications.1

Corporate boards, ownership structure and firm performance in an environment of severe political and economic crisis

This study examines the relationship between board and ownership structures and firm performance in an environment of severe political and economic crisis. Using panel data from the Zimbabwe Stock Exchange (ZSE) for the period 2000-2005, we split the period into prepresidential election period (2000-2002) (a relatively stable political and economic period) and post-presidential election period (2003-2005) (a hostile political and economic period) to capture the differences in the political and economic landscape. We find that board size, ownership concentration and executive directors’ share ownership increased whilst the proportion of nonexecutive directors reduced in the post-presidential election period. Employing a system Generalized Method of Moments (GMM) approach, we find that performance is positively related to board size and ownership concentration in the post- (but not in the pre-) presidential election period. The results also show that performance is negatively related to executive directors’ share ownership in the post-presidential election period, but positively related in the pre-presidential election period. The proportion of non-executive directors is negative and significant in both periods. These findings support the notion that the effects of board and ownership structures depend on the nature of the firm’s environment, and therefore have important implications for policy-makers

Temporary bilateral sensorineural hearing loss following cardiopulmonary bypass -A case report-

Sudden sensorineural hearing loss has been reported to occur following anesthesia and various non-otologic surgeries, mostly after procedures involving cardiopulmonary bypass. Unilateral sensorineural hearing loss resulting from microembolism is an infrequent complication of cardiopulmonary bypass surgery that has long been acknowledged. Moreover, there are few reports on the occurrence of bilateral sensorineural hearing loss without other neurologic deficits and its etiology has also not been determined. We describe here a rare case of bilateral hearing loss without other neurologic deficits in an otherwise healthy 27-year-old woman who underwent cardiopulmonary bypass surgery for repair of severe mitral valve stenosis. The patient suffered from profound sensorineural hearing loss in both ears that was recognized immediately upon extubation, and audiometry tests confirmed the diagnosis. Without any treatment, her hearing recovered almost completely by the time of her discharge one week after surgery

Withdrawal of Immunosuppression in Pediatric Liver Transplant Recipients in Korea

Purpose: We identified pediatric liver transplant recipients with successful withdrawal of immunosuppression who developed tolerance in Korea. Materials and Methods: Among 105 pediatric patients who received liver transplantation and were treated with tacrolimus-based immunosuppressive regimens, we selected five (4.8%) patients who had very low tacrolimus trough levels. Four of them were noncompliant with their medication and one was weaned off of immunosuppression due to life threatening posttransplant lymphoproliferative disorder. We reviewed the medical records with regard to the relationship of the donor-recipients, patient characteristics and prognosis, including liver histology, and compared our data with previous reports. Results: Four patients received the liver transplantation from a parent donor and one patient from a cadaver donor. A trial of withdrawal of the immunosuppressant was started a median of 45 months after transplantation (range, 14 months to 60 months), and the period of follow up after weaning from the immunosuppressant was a median of 32 months (range, 14 months to 82 months). None of the five patients had rejection episodes after withdrawal of the immunosuppression; they maintained normal graft function for longer than 3 years (median, 38 months; range, 4 to 53 months). The histological findings of two grafts 64 and 32 months after weaning-off of the medication showed no evidence of chronic rejection. Conclusion: The favorable markers for successful withdrawal of immunosuppression were 1) long-term (> 3 years) stable graft function, 2) no rejection for longer than 1 year after withdrawal of immunosuppression

The Efficacy of the Prophylactic Use of Octreotide after a Pancreaticoduodenectomy

This study was performed to analyze the efficacy of the prophylactic use of octreotide (Novartis, Stein, Switzerland) for pancreatic fistula following a pancreaticoduodenectomy. The medical records of 190 patients who underwent a pancreaticoduodenectomy at the Samsung Medical Center in Seoul, Korea between January 2000 and December 2002 were reviewed. Patients were divided into either the octreotide (n = 81) or control group (n = 109). The octreotide group received subcutaneous injections of 100 µg of octreotide every 12 hours for more than five days after surgery. The control group was not treated with octreotide. The criterion of pancreatic fistula was the drainage of the amylase rich fluid, over 500 U/mL in the three days after surgery. The morbidity and mortality rates were 32.1% and 1.2% in the octreotide group and 31.2% and 0% in the control group, respectively. Pancreatic fistula was the second most common complication (8.4%). In the univariate analysis, octreotide was ineffective in reducing pancreatic fistula (p = 0.26). However, in the multivariate regression analysis, combined gastrectomy (p = 0.018), cellular origin of the disease (p = 0.049), and use of octreotide (p = 0.044) were the risk factors that increased the frequency of pancreatic fistula. Therefore, the routine use of octreotide after a pancreaticoduodenectomy should be avoided until a worldwide consensus is established

A case of hepatocellular carcinoma in the caudate lobe successfully treated by transcatheter arterial chemoembolization using drug-eluting beads

Hepatocellular carcinoma (HCC) in the caudate lobe remains one of the most intricate locations where various treatments tend to pose problems with regard to the optimal approach. Surgical resection has been regarded as the most effective treatment; however, isolated resection of the caudate lobe is strenuous and associated with a high rate of early recurrence. Percutaneous ablation might be technically difficult or impossible to perform due to the deep location of tumors and adjacent large vessels. Treatment with drug-eluting beads (DEB) can potentially enhance the therapeutic efficacy for patients with unresectable HCC by drawing on the slower, more consistent drug delivery process. We described a case of a 62-year-old man with HCC in the caudate lobe who was successfully treated by DEB

Highly Pathogenic Avian Influenza Virus (H5N1) in Domestic Poultry and Relationship with Migratory Birds, South Korea

During the 2006–2007 winter season in South Korea, several outbreaks of highly pathogenic avian influenza virus (H5N1) were confirmed among domestic poultry and in migratory bird habitats. Phylogenetic analysis showed that all isolates were closely related and that all belong to the A/bar-headed goose/Qinghai/5/2005–like lineage rather than the A/chicken/Korea/ES/2003–like lineage

Genome-wide SNP identification and QTL mapping for black rot resistance in cabbage

BACKGROUND: Black rot is a destructive bacterial disease causing large yield and quality losses in Brassica oleracea. To detect quantitative trait loci (QTL) for black rot resistance, we performed whole-genome resequencing of two cabbage parental lines and genome-wide SNP identification using the recently published B. oleracea genome sequences as reference. RESULTS: Approximately 11.5 Gb of sequencing data was produced from each parental line. Reference genome-guided mapping and SNP calling revealed 674,521 SNPs between the two cabbage lines, with an average of one SNP per 662.5 bp. Among 167 dCAPS markers derived from candidate SNPs, 117 (70.1%) were validated as bona fide SNPs showing polymorphism between the parental lines. We then improved the resolution of a previous genetic map by adding 103 markers including 87 SNP-based dCAPS markers. The new map composed of 368 markers and covers 1467.3 cM with an average interval of 3.88 cM between adjacent markers. We evaluated black rot resistance in the mapping population in three independent inoculation tests using F₂:₃ progenies and identified one major QTL and three minor QTLs. CONCLUSION: We report successful utilization of whole-genome resequencing for large-scale SNP identification and development of molecular markers for genetic map construction. In addition, we identified novel QTLs for black rot resistance. The high-density genetic map will promote QTL analysis for other important agricultural traits and marker-assisted breeding of B. oleracea.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]