bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of bleaching agents and Tooth Mousse™ on human enamel hardness
Authors: Alkhtib Asmaa , Manton David J. , Burrow Michael F. , Saber‐Samandari Saeed , Palamara Joseph E.A. , Gross Kārlis A. , Reynolds Eric C.
Published: September 2012

Objective

The aim of this laboratory study was to investigate the effect of three commercial bleaching agents and Tooth Mousse™ containing 10% w/w casein phosphopeptide–amorphous calcium phosphate on the hardness of tooth enamel.

Methods

Sixteen human enamel specimens were exposed to one of three commercial bleaching agents with or without subsequent exposure to Tooth Mousse™. Nanoindentation was used to measure the hardness and reduced modulus before and after treatments.

Results

When bleaching materials were applied for a short period of time following the manufacturers' instructions, there was an increase in enamel hardness and reduced modulus for some bleaching groups, with no statistically significant difference from the baseline values. After extended bleaching periods a statistically significant decrease in enamel hardness and reduced modulus was found and after applying Tooth Mousse™ post‐bleaching, the hardness and reduced modulus returned to close to baseline values.

Conclusion

The application of bleaching agents for an extended period of time significantly decreases enamel hardness and the reduced modulus. The application of Tooth Mousse™ after bleaching was able to reestablish the baseline enamel hardness and reduced modulus, decreasing the adverse effects of bleaching enamel.
Differentiated expression of membrane type metalloproteinases (MMP‐14, MMP‐15) and pro‐MMP2 in laryngeal squamous cell carcinoma. A novel mechanism
Authors: Bodnar Magdalena , Szylberg Lukasz , Kazmierczak Wojciech , Marszalek Andrzej
Published: September 2012

Cancer progression involves multiple proteolytic interactions, with metalloproteinases (MMPs) performing a crucial role. MMP‐2, a major MMP, plays a key role in the degradation of basement membranes. Mechanisms underlying MMP‐2 activation had to be investigated. Membrane‐type matrix metalloproteinases are not only responsible for the regulation of extracellular matrix remodeling, but also involved in the activation of several inactive MMPs. The aim of this study was to evaluate the expression of pro‐MMP2, MMP‐14, and MMP‐15 in tumor cells and tumor stroma. Immunohistochemical studies were performed on paraffin‐embedded tissue sections including laryngeal squamous cell carcinoma (SCC). We found the expression of pro‐MMP2 in 58% of cases, MMP‐14 in 78%, and MMP‐15 in 98% of cases of SCC. In all tumor cases, we revealed a higher expression of pro‐MMP2 in tumor stoma than in tumor cells. The expression of MMP‐14 and MMP‐15 was higher in tumor cells than in the stroma. Moreover, we found a statistically significant difference between the expression of MMP‐14 and MMP‐15 in the tumor in comparison with the surrounding stroma (P < 0.05). An analysis of expression levels of MT‐MMPs by classification trees showed that the probability of metastases was related to decreased expression of MMP‐14 and increased expression of MMP‐15. Our results may suggest that tumor cells with low MMP‐14 expression invade tumor stroma and form metastases. Probably, in such cases, tumor progression is stimulated by MMP‐15 in an MMP‐14 independent pathway, a novel (alternative) mechanism.
Pectobacterium carotovorum subsp. brasiliense Causing Soft Rot on Paprika in Korea
Authors: Choi Okhee , Kim Jinwoo
Published: September 2012

During summer 2011 in South Korea, severe fruit rot of paprika was observed, causing severe economic losses in paprika production. Symptoms of fruit and pedicel decay were consistent with symptoms caused by Pectobacterium carotovorum subsp. brasiliense (Pcb) as recently described in Brazil, the United States, Israel and South Africa. Physiological analysis and pathogenicity test of strains isolated from paprika fruit revealed that the pathogen was the bacterium Pcb. Sequencing and phylogenetic analysis of the 16S rDNA and partial 16S–23S rDNA intergenic spacer region confirmed that the isolates were Pcb. This is the first report of Pcb in Korea, which has a significant economic impact on Korean paprika production.
Effect of parenteral administration of glutamine on autophagy of liver cell and immune responses in weaned calves
Authors: Hu Z. Y. , Su H. W. , Li S. L. , Cao Z. J.
Published: September 2012

The objectives of this study were to determine the effects of an increased jugular supply of L‐Gln on post‐weaning growth, immune responses, intestinal morphology and autophagy of weaned calves. At 35 days of age, 24 Holstein calves (initial 50 ± 1.5 kg; 35 ± 2 day of age) were randomly allocated to four treatments, and each treatment included five male and one female calves. Holstein calves were assigned to treatments of (i) i.v. infusion of 2 l of 0.85% NaCl, Control group [C]; (ii) i.v. infusion of 8 g/day of L‐Gln mixed with 2 l of 0.85% NaCl solution [L]; (iii) i.v. infusion of 16 g/day of L‐Gln mixed with 2 l of 0.85% NaCl solution [M]; and (iv) i.v. infusion of 32 g/day of L‐Gln mixed with 2 l of 0.85% NaCl [H]; The infusion was 2 h/day for each of 14 consecutive days starting on day 1 after weaning. Feed and water were freely available to all calves. All calves were killed on the 14th day post‐weaning for measurements of autophagy of liver cell and intestinal morphology. Gln has no effect on dry matter intake (DMI) and average daily gain (ADG). Gln infusion increased quadratically the abundance of CD4+, monocyte and the ratio of CD4+/CD8+. The urea N, Gln and Glucose in plasma increased linearly with increasing Gln loads. Gln infusion increased quadratically villus height and crypt depth of intestine. The autophagy level of liver cell was improved with the Gln infusion dose increased.
Impacts of Microcystis on algal biodiversity and use of new technology to remove Microcystis and dissolved nutrients
Authors: Magrann Tracey , Dunbar Stephen G. , Boskovic Danilo S. , Hayes William K.
Published: September 2012

Cyanobacteria often dominate eutrophic lakes, outcompeting green algae that are required by fish and zooplankton. This study was undertaken to ascertain the impact of the cyanobacterium, Microcystis, on algal biodiversity. Under laboratory conditions, we found that the presence of Microcystis decreased phyla richness by 58%, phyla evenness by 47%, genera richness by 66% and genera evenness by 51%. Analysis by mixed anovas demonstrated a significant interaction between treatment and time and confirmed a significant reduction in richness and evenness of phyla and genera. We also conducted a phosphate restriction assay on the algae in Mason Lake (Irvine, CA, USA) and found that the threshold needed for algal growth there was 0.02 mg L−1 PO4. A pilot study was then conducted to test the effectiveness of the Blue Pro™ water treatment facility in removal of this colonial organism from Mason Lake, in addition to removal of dissolved nutrients required for its growth. We measured a 97% reduction in Microcystis cells, a 72% reduction in chlorophyll‐a, and a 96% reduction in phosphate after just one 10 min cycle through the unit. Our study demonstrated that removal of Microcystis colonies may allow green algae to increase in numbers. This may improve algal biodiversity, which will benefit zooplankton and fishes.
A case study of water retention and ecosystem functioning restoration in Wenying Lake (China)
Authors: Pan Gang , Zhang Zengguang , Li Liwen , Li Liang , Wang Dan , Matos Maria C.
Published: September 2012

Wenying Lake in Datong, China, has been drying for the last several years. Analysis of standard penetration test data revealed that a missing waterproof layer of silt soil and silty clay in the south part of the lake, resulting from frequent flood flushing, was responsible for the water loss from the lake. Accordingly, 6.7 × 105 m2 of geosynthetic clay liner (GCL) was used in May 2010 to repair the area of sediment exhibiting the water leakage, equivalent to 15.6% of the total lake bottom area. Approximately 4.1 × 106 m3 of floodwater was then diverted from upstream rivers to the lake. Eight months later, about 0.9 × 106 m3 of the water was retained, with the water loss being reduced from 4.0 to 1.1 m3 m−2 year−1. Ecologically safe and cost‐effective clay materials also can be used to furthermore improve the water retention characteristics. Modelling results indicated that capping the whole lake with a 2 cm layer of bentonite with a permeability coefficient of 5.0 × 10−9 cm s−1 could reduce the sediment water leakage to 0.04 m3 m−2 year−1. The quality of the retained water after GCL treatment project was poor, with a total nitrogen concentration of 11.0 mg L−1 and sulphate 307.0 mg L−1, which were 5 and 300 times higher, respectively, than the Chinese class V surface water standard. Restoration of aquatic vegetation in the lake and constructed wetlands near the lake inlets could be helpful to improve the lake’s water quality over the long term.
Challenges and strategies in transcriptome assembly and differential gene expression quantification. A comprehensive in silico assessment of RNA‐seq experiments
Authors: Vijay Nagarjun , Poelstra Jelmer W. , Künstner Axel , Wolf Jochen B. W.
Published: September 2012

Transcriptome Shotgun Sequencing (RNA‐seq) has been readily embraced by geneticists and molecular ecologists alike. As with all high‐throughput technologies, it is critical to understand which analytic strategies are best suited and which parameters may bias the interpretation of the data. Here we use a comprehensive simulation approach to explore how various features of the transcriptome (complexity, degree of polymorphism π, alternative splicing), technological processing (sequencing error ε, library normalization) and bioinformatic workflow (de novo vs. mapping assembly, reference genome quality) impact transcriptome quality and inference of differential gene expression (DE). We find that transcriptome assembly and gene expression profiling (EdgeR vs. BaySeq software) works well even in the absence of a reference genome and is robust across a broad range of parameters. We advise against library normalization and in most situations advocate mapping assemblies to an annotated genome of a divergent sister clade, which generally outperformed de novo assembly (Trans‐Abyss, Trinity, Soapdenovo‐Trans). Transcriptome complexity (size, paralogs, alternative splicing isoforms) negatively affected the assembly and DE profiling, whereas the effects of sequencing error and polymorphism were almost negligible. Finally, we highlight the challenge of gene name assignment for de novo assemblies, the importance of mapping strategies and raise awareness of challenges associated with the quality of reference genomes. Overall, our results have significant practical and methodological implications and can provide guidance in the design and analysis of RNA‐seq experiments, particularly for organisms where genomic background information is lacking.
Historical stocking data and 19th century DNA reveal human‐induced changes to native diversity and distribution of cutthroat trout
Authors: Metcalf J. L. , Love Stowell S. , Kennedy C. M. , Rogers K. B. , McDonald D. , Epp J. , Keepers K. , Cooper A. , Austin J. J. , Martin A. P.
Published: September 2012

Many species are threatened with extinction and efforts are underway worldwide to restore imperilled species to their native ranges. Restoration requires knowledge of species' historical diversity and distribution. For some species, many populations were extirpated or individuals moved beyond their native range before native diversity and distribution were documented, resulting in a lack of accurate information for establishing restoration goals. Moreover, traditional taxonomic assessments often failed to accurately capture phylogenetic diversity. We illustrate a general approach for estimating regional native diversity and distribution for cutthroat trout in the Southern Rocky Mountains. We assembled a large archive of historical records documenting human‐mediated change in the distribution of cutthroat trout (Oncorhynchus clarkii) and combined these data with phylogenetic analysis of 19th century samples from museums collected prior to trout stocking activities and contemporary DNA samples. Our study of the trout in the Southern Rocky Mountains uncovered six divergent lineages, two of which went extinct, probably in the early 20th century. A third lineage, previously declared extinct, was discovered surviving in a single stream outside of its native range. Comparison of the historical and modern distributions with stocking records revealed that the current distribution of trout largely reflects intensive stocking early in the late 19th and early 20th century from two phylogenetically and geographically distinct sources. Our documentation of recent extinctions, undescribed lineages, errors in taxonomy and dramatic range changes induced by human movement of fish underscores the importance of the historical record when developing and implementing conservation plans for threatened and endangered species.
[PSI+] prion variant establishment in yeast
Authors: Sharma Jaya , Liebman Susan W.
Published: September 2012

Differences in the clinical pathology of mammalian prion diseases reflect distinct heritable conformations of aggregated PrP proteins, called prion strains. Here, using the yeast [PSI+] prion, we examine the de novo establishment of prion strains (called variants in yeast). The [PSI+] prion protein, Sup35, is efficiently induced to take on numerous prion variant conformations following transient overexpression of Sup35 in the presence of another prion, e.g. [PIN+]. One hypothesis is that the first [PSI+] prion seed to arise in a cell causes propagation of only that seed's variant, but that different variants could be initiated in different cells. However, we now show that even within a single cell, Sup35 retains the potential to fold into more than one variant type. When individual cells segregating different [PSI+] variants were followed in pedigrees, establishment of a single variant phenotype generally occurred in daughters, granddaughters or great‐granddaughters – but in 5% of the pedigrees cells continued to segregate multiple variants indefinitely. The data are consistent with the idea that many newly formed prions go through a maturation phase before they reach a single specific variant conformation. These findings may be relevant to mammalian PrP prion strain establishment and adaptation.
Prime time for minor subunits of the type II secretion and type IV pilus systems
Authors: Burrows Lori L.
Published: September 2012

The type II secretion system (T2SS) exports folded proteins from the periplasms of Gram‐negative bacteria. The type IV pilus system (T4PS) is a multifunctional machine used for adherence, motility and DNA transfer in bacteria and archaea. Partial sequence identity between the two systems suggests that they are related and might function via a similar mechanism, the dynamic assembly and disassembly of pseudopilus (T2SS) or pilus (T4PS) filaments. The major subunit in each system is thought to form the bulk of the (pseudo)pilus, while minor (low‐abundance) subunits have proposed roles in assembly initiation, antagonism of disassembly, or modulation of (pseudo)pilus functional properties. In this issue, Cisneros et al. () extend their previous finding that pseudopilus assembly is primed by the minor pseudopilins, showing that the same proteins can initiate assembly of Escherichia coli T4P. Similarly, they show that the E. coli minor pilins prime the polymerization of T2S pseudopili, although unlike genuine pseudopili, the chimeric filaments did not support secretion. This work reinforces the notion of a common assembly mechanism for the T2S and T4P systems.
Outcomes of general anesthesia for noncardiac surgery in a series of patients with Fontan palliation
Authors: Rabbitts Jennifer A. , Groenewald Cornelius B. , Mauermann William J. , Barbara David W. , Burkhart Harold M. , Warnes Carole A. , Oliver William C. , Flick Randall P.
Published: September 2012

Objectives

To describe the experience of a single, tertiary care institution in the care of patients with Fontan physiology undergoing anesthesia for noncardiac surgery.

Background

The Fontan procedure was developed in 1971 to palliate patients with univentricular cardiac physiology leading to long‐term survival of these patients, who may now present as adults for noncardiac surgery.

Methods

We retrospectively reviewed the medical records of Fontan patients 16 years and older who underwent general anesthesia for noncardiac surgery at Mayo Clinic in Rochester, Minnesota. Preoperative data, perioperative course, intraoperative and postoperative hemodynamic, pulmonary, cardiovascular, and renal complications were described.

Results

Thirty‐nine general anesthetics were administered to 31 patients for noncardiac surgery after Fontan palliation. Perioperative complications occurred in 12 of the 39 (31%) noncardiac surgeries, and there was one postoperative death that occurred on day 13 after ventral hernia repair. The two patients who had complications that did not resolve (long‐term dialysis and death) had ejection fractions well below the mean for the group (22% and 28%).

Conclusion

It may be more appropriate for Fontan patients to undergo anesthesia for noncardiac surgery in a tertiary institution, particularly patients with an ejection fraction of <30%. Intraoperative arterial blood pressure monitoring and overnight admission are likely appropriate for most cases.
Analysis of genotypic variation for normalized difference vegetation index and its relationship with grain yield in winter wheat under terminal heat stress
Authors: Hazratkulova Shahnoza , Sharma Ram C. , Alikulov Safar , Islomov Sarvar , Yuldashev Tulkin , Ziyaev Zafar , Khalikulov Zakir , Ziyadullaev Zokhid , Turok Jozef
Published: September 2012

Normalized difference vegetation index (NDVI), which is a measure of leaf greenness (chlorophyll content), is considered to be correlated with crop productivity. This study was conducted to examine genotypic variations for NDVI at different growth stages and its relationship to yield in winter wheat under terminal heat stress. Thirty winter wheat genotypes were evaluated at two locations in 2009–2010 and 2010–2011 in Uzbekistan. The NDVI was recorded at booting, heading, milk and dough stages. The wheat genotypes differed significantly for NDVI at each stage. Grain yield ranged from 3.9 to 6.1 t/ha. Wheat genotypes differed in per cent decline in NDVI from booting to dough stage. However, several high‐yielding genotypes maintained higher NDVI than low‐yielding genotypes when heat stress was evident. The findings suggest change in NDVI during heat stress could be a measure of tolerance. The positive correlation of NDVI with grain yield suggests that it could be used as an indirect selection criterion for identifying physiologically superior, high‐yielding wheat lines under terminal heat stress.
Mutants impaired in vacuolar metal mobilization identify chloroplasts as a target for cadmium hypersensitivity in Arabidopsis thaliana
Authors: MOLINS HÉLÈNE , MICHELET LAURE , LANQUAR VIVIANE , AGORIO ASTRID , GIRAUDAT JÉRÔME , ROACH THOMAS , KRIEGER‐LISZKAY ANJA , THOMINE SÉBASTIEN
Published: September 2012

Cadmium (Cd) is highly toxic to plants causing growth reduction and chlorosis. It binds thiols and competes with essential transition metals. It affects major biochemical processes such as photosynthesis and the redox balance, but the connection between cadmium effects at the biochemical level and its deleterious effect on growth has seldom been established. In this study, two Cd hypersensitive mutants, cad1‐3 impaired in phytochelatin synthase (PCS1), and nramp3nramp4 impaired in release of vacuolar metal stores, have been compared. The analysis combines genetics with measurements of photosynthetic and antioxidant functions. Loss of AtNRAMP3 and AtNRAMP4 function or of PCS1 function leads to comparable Cd sensitivity. Root Cd hypersensitivities conferred by cad1‐3 and nramp3nramp4 are cumulative. The two mutants contrast in their tolerance to oxidative stress. In nramp3nramp4, the photosynthetic apparatus is severely affected by Cd, whereas it is much less affected in cad1‐3. In agreement with chloroplast being a prime target for Cd toxicity in nramp3nramp4, the Cd hypersensitivity of this mutant is alleviated in the dark. The Cd hypersensitivity of nramp3nramp4 mutant highlights the critical role of vacuolar metal stores to supply essential metals to plastids and maintain photosynthetic function under Cd and oxidative stresses.
Development and Validation of the Performance Management Behavior Questionnaire
Authors: Kinicki Angelo J. , Jacobson Kathryn J. L. , Peterson Suzanne J. , Prussia Gregory E.
Published: September 2012

This study integrates literature on performance management and organizational behavior with input from managers to develop a 27‐item measure of performance management behavior. We used 8 samples, including multisource data, to develop a reliable multidimensional scale that replicated across samples. The scale demonstrated content validity, both convergent and discriminant validity, and incremental validity, and criterion‐related validity was established through the scale's relation with measures of management effectiveness and job attitudes. Overall, this study suggests that the Performance Management Behavior Questionnaire (PMBQ) is a reliable and valid measure and that performance management behaviors have important implications for both employees and organizations.
Spotlight on the Followers: An Examination of Moderators of Relationships Between Transformational Leadership and Subordinates’ Citizenship and Taking Charge
Authors: Li Ning , Chiaburu Dan S. , Kirkman Bradley L. , Xie Zhitao
Published: September 2012

Drawing on substitutes for leadership theory, we revisit an often taken‐for‐granted assumption that transformational leadership is a universally positive management practice by examining subordinate‐based aspects attenuating the relationship between transformational leadership and followers’ citizenship and taking charge. Using data collected from 196 followers and their leaders situated in 55 workgroups in 2 Chinese organizations, we found that followers’ citizenship and taking charge were not influenced by transformational leadership when followers perceived leaders as prototypical and were highly identified with their workgroups. Furthermore, following a differential pattern for citizenship and taking charge, followers’ traditionality weakened the relationship with citizenship, whereas followers’ learning goal orientation attenuated the relationship with taking charge. Introducing contingencies and specifying their underlying logic broadens the current theoretical spectrum for both substitutes for leadership and transformational leadership.
The Number of Regulatory T Cells Correlates with Hemodynamic Improvement in Patients with Inflammatory Dilated Cardiomyopathy After Immunoadsorption Therapy
Authors: Bulut D. , Creutzenberg G. , Mügge A.
Published: September 2012

Inflammatory DCM (iDCM) may be related to autoimmune processes. An immunoadsorption (IA) has been reported to improve cardiac hemodynamics. The benefit of IA is probably related to the removal of autoantibodies. A recent study suggests additional effects of IA on the T cell–mediated immune reactions, especially on regulatory T cells (Tregs). In this prospective study, the correlation between the level of Tregs and improvement of myocardial contractility in response to IA in patients with iDCM was investigated. Patients (n = 18) with iDCM, reduced left ventricular (LV) ejection fraction (<35%), were enrolled for IA. Before and 6 months after IA, LV systolic function was assessed by echocardiography, and blood levels of Tregs were quantified by FACS analysis. Patients (n = 12) with chronic ischaemic heart failure and comparable reduced LV‐EF served as controls. IA improved LV‐EF in 12 of 18 patients at 6‐month follow‐up. These patients were classified as ‘IA responder’. In 6 patients, LV‐EF remained unchanged. At baseline, IA responder and non‐responder subgroups showed similar values for C‐reactive protein, white blood cells, lymphocytes and T helper cells, but they differ for the number of circulating Tregs (responder: 2.32 ± 1.38% versus non‐responder: 4.86 ± 0.28%; P < 0.01). Tregs increased significantly in the IA responders, but remained unchanged in the IA non‐responders. In patients with ischaemic cardiomyopathy, none of these values changed over time. A low level of Tregs in patients with chronic iDCM may characterize a subset of patients who do best respond to IA therapy.
Influenza A H1N1/2009 infection in pediatric solid organ transplant recipients
Authors: Gavaldà J. , Cabral E. , Alonso E. , Perez‐Romero P. , Pérez A. , Quintero J. , Campins M. , Vilalta R. , Alonso A. , Len O. , Navarro M. , Nieto J. , Jara P. , Charco R. , Pahissa A. , Cordero E.
Published: September 2012

Aim and method

The aim of this study was to describe the clinical characteristics and outcome of pandemic influenza A H1N1/2009 (pH1N1) infection, in a retrospective cohort of pediatric patients with kidney and/or liver transplant and confirmed pH1N1 infection from June to December 2009, diagnosed in 2 Spanish teaching hospitals.

Results

Forty‐nine patients were included. Pneumonia was diagnosed in 4 patients (8.2%), and 3 of them required respiratory support. There were no related deaths.

Conclusion

Antiviral treatment within 48 h was associated with a lower likelihood of pneumonia (0/38, 0%) than treatment started after 48 h (4/11, 36.3%) (P < 0.01).
The ammonium/nitrate ratio is an input signal in the temperature‐modulated, SNC1‐mediated and EDS1‐dependent autoimmunity of nudt6‐2 nudt7
Authors: Wang Hai , Lu Yuqing , Liu Pei , Wen Wei , Zhang Jianhua , Ge Xiaochun , Xia Yiji
Published: September 2012

AtNUDT7 was reported to be a negative regulator of EDS1‐mediated immunity in Arabidopsis. However, the underlying molecular and genetic mechanism of the AtNUDT7‐regulated defense pathway remains elusive. Here we report that AtNUDT7 and its closest paralog AtNUDT6 function as novel negative regulators of SNC1, a TIR‐NB‐LRR‐type R gene. SNC1 is upregulated at transcriptional and possibly post‐transcriptional levels in nudt6‐2 nudt7. The nudt6‐2 nudt7 double mutant exhibits autoimmune phenotypes that are modulated by temperature and fully dependent on EDS1. The nudt6‐2 nudt7 mutation causes EDS1 nuclear accumulation shortly after the establishment of autoimmunity caused by the temperature shift. We found that a low ammonium/nitrate ratio in growth media leads to a higher level of nitrite‐dependent nitric oxide (NO) production in nudt6‐2 nudt7, and NO acts in a positive feedback loop with EDS1 to promote the autoimmunity. The low ammonium/nitrate ratio also enhances autoimmunity in snc1‐1 and cpr1, two other autoimmune mutants in Arabidopsis. Our study indicates that Arabidopsis senses the ammonium/nitrate ratio as an input signal to determine the amplitude of the EDS1‐mediated defense response, probably through the modulation of NO production.
On the use of expansion series for stream ciphers
Authors: Diem Claus
Published: September 2012

From power series expansions of functions on curves over finite fields, one can obtain sequences with perfect or almost perfect linear complexity profile. It has been suggested by various authors to use such sequences as key streams for stream ciphers. In this work, we show how long parts of such sequences can be computed efficiently from short ones. Such sequences should therefore be considered to be cryptographically weak. Our attack leads in a natural way to a new measure of the complexity of sequences which we call expansion complexity.
Spectroscopic Measurements of Hydrogen and Oxygen in Shielding Gas During Plasma Arc Welding
Authors: Pang Q. , Pang T. , McClure J. C. , Nunes A. C.
Published: September 2012

In Situ optical spectroscopy has been used on plasma arc welded 2219 aluminum to measure both the average temperature of and the amount of hydrogen and oxygen in the welding arc. Hydrogen and oxygen levels of less than 75 ppm can be readily detected. It is shown that below a critical shield gas flow rate, the rapid invasion of atmosphere can be readily detected by this technique, and that this critical flow rate is dependent on the temperature of the arc.
Meshless Local Petrov-Galerkin Method for Three-Dimensional Heat Transfer Analysis
Authors: Tian Jun , Rao Singiresu S.
Published: September 2012

A meshless local Petrov-Galerkin (MLPG) method is proposed to obtain the numerical solution of nonlinear heat transfer problems. The moving least squares scheme is generalized to construct the field variable and its derivatives continuously over the entire domain. The essential boundary conditions are enforced by the direct scheme. By defining a radiation heat transfer coefficient, the nonlinear boundary value problem is solved as a sequence of linear problems each time updating the radiation heat transfer coefficient. The matrix formulation is used to drive the equations for a three dimensional nonlinear coupled radiation heat transfer problem. By using the MPLG method, along with the linearization of the nonlinear radiation problem, a new numerical approach is proposed to find the solution of the coupled heat transfer problem. A numerical study of the dimensionless size parameters for the quadrature and support domains is conducted to find the most appropriate values to ensure convergence of the nodal temperatures to the correct values quickly. Numerical examples are presented to illustrate the applicability and effectiveness of the proposed methodology for the solution of one-, two-, and three-dimensional heat transfer problems involving radiation with different types of boundary conditions. In each case, the results obtained using the MLPG method are compared with those given by the finite element method (FEM) method for validating the results.
Transient Calorimetric Measurement Method for Total Hemispherical Emissivity
Authors: Fu Tairan , Tan Peng
Published: September 2012

The transient calorimetric technique was used to measure the total hemispherical emissivity of conductive materials. The emissivity was measured in a small central region of a thin strip heated electrically in a vacuum chamber. The axial heat transfer along the sample and the heat losses from the wires were considered in the transient heat transfer calculations. An appropriate time interval for the hot sample cooling rate is needed to improve the emissivity solution accuracy. Two ways were used to analyze the data, based on the known specific heat and the assumed functions of the emissivity and the specific heat. Comparisons with steady-state data showed that their results are very similar with a maximum difference of only 13% (944 K). Therefore, the transient method based on the function assumption is a good choice for measurements when there are inaccurate or insufficient specific heat data at the desired temperatures. Since ferromagnetic materials have Curie points at higher temperatures, this study also investigated the applicability of the transient calorimetric technique for high temperature emissivity measurements. For higher temperatures above the Curie point, the steady-state method is more accurate than the transient method. These analyses provide a comprehensive understanding of the transient method for measuring the total hemispherical emissivity.
Impact of Manufacturing Variability on Multistage High-Pressure Compressor Performance
Authors: Lange Alexander , Voigt Matthias , Vogeler Konrad , Schrapp Henner , Johann Erik , Gümmer Volker
Published: September 2012

The present paper introduces a novel approach for considering manufacturing variability in the numerical simulation of a multistage high-pressure compressor (HPC). The manufacturing process is investigated by analyzing three of a total of ten rotor rows. Therefore, 150 blades of each of the three rows were 3D scanned to obtain surface meshes of real blades. The deviation of a scanned blade to the design intent is quantified by a vector of 14 geometric parameters. Interpolating the statistical properties of these parameters provides the manufacturing scatter for all ten rotor rows expressed by 140 probability density functions. The probabilistic simulation utilizes the parametric scatter information for generating 200 virtual compressors. The CFD analysis provides the performance of these compressors by calculating speed lines. Postprocessing methods are applied to statistically analyze the obtained results. It was found that the global performance parameters show a significantly wider scatter range for higher back pressure levels. The correlation coefficient and the coefficient of importance are utilized to identify the sensitivity of the results to the geometric parameters. It turned out that the sensitivities strongly shift for different operating points. While the leading edge geometry of all rotor rows dominantly influences the overall performance at maximum efficiency, the camber line parameters of the front stages become more important for higher back pressure levels. The analysis of the individual stage performance confirms the determining importance of the front stages—especially for highly throttled operating conditions. This leads to conclusions regarding the robustness of the overall HPC, which is principally determined by the efficiency and pressure rise of the front stages.
Low homologous temperature (<0.2) sputtering of indium films on silicon
Authors: Dang Tuoc , Shima Darryl , Balakrishnan Ganesh , Chen Antao , Bedford Robert G.
Published: September 2012

Substrate temperature is used to control the film morphology and packing of indium metal deposited by DC sputtering. Indium is sputtered on silicon at room- and liquid nitrogen cryogenic-temperatures resulting in very different homologous temperatures of 0.7 and 0.17. The deposition of the indium film at <0.2 homologous temperature results in increased film packing density, reduced voids, and a near specular indium surface which is very different from the extremely rough room temperature sample. The samples are characterized using atomic force microscope, scanning electron microscopy, transmission electron microscopy, and selective area electron diffraction. This technique for achieving low surface roughness indium has many potential uses for microelectronic packaging.
UV ozone treatment for improving contact resistance on graphene
Authors: Wei Chen Chung , Ren Fan , Chi Gou-Chung , Hung Sheng-Chun , Huang Y. P. , Kim Jihyun , Kravchenko Ivan I. , Pearton Stephen J.
Published: September 2012

Optimized UV ozone cleaning of graphene layers on SiO2/Si substrates is shown to improve contact resistance of e-beam evaporated Ti/Au contacts by three orders of magnitude (3 × 10−6 Ω-cm2) compared to untreated surfaces (4 × 10−3 Ω-cm2). Subsequent annealing at 300 °C lowers the minimum value achieved to 7 × 10−7 Ω-cm2. Ozone exposure beyond an optimum time (6 min in these experiments) led to a sharp increase in sheet resistance of the graphene, producing degraded contact resistance. The UV ozone treatment is a simple and effective method for producing high quality contacts to graphene.
EPID‐based verification of the MLC performance for dynamic IMRT and VMAT
Authors: Rowshanfarzad Pejman , Sabet Mahsheed , Barnes Michael P. , O'Connor Daryl J. , Greer Peter B.
Published: September 2012

Purpose:

In advanced radiotherapy treatments such as intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), verification of the performance of the multileaf collimator (MLC) is an essential part of the linac QA program. The purpose of this study is to use the existing measurement methods for geometric QA of the MLCs and extend them to more comprehensive evaluation techniques, and to develop dedicated robust algorithms to quantitatively investigate the MLC performance in a fast, accurate, and efficient manner.

Methods:

The behavior of leaves was investigated in the step‐and‐shoot mode by the analysis of integrated electronic portal imaging device (EPID) images acquired during picket fence tests at fixed gantry angles and arc delivery. The MLC was also studied in dynamic mode by the analysis of cine EPID images of a sliding gap pattern delivered in a variety of conditions including different leaf speeds, deliveries at fixed gantry angles or in arc mode, and changing the direction of leaf motion. The accuracy of the method was tested by detection of the intentionally inserted errors in the delivery patterns.

Results:

The algorithm developed for the picket fence analysis was able to find each individual leaf position, gap width, and leaf bank skewness in addition to the deviations from expected leaf positions with respect to the beam central axis with sub‐pixel accuracy. For the three tested linacs over a period of 5 months, the maximum change in the gap width was 0.5 mm, the maximum deviation from the expected leaf positions was 0.1 mm and the MLC skewness was up to 0.2°. The algorithm developed for the sliding gap analysis could determine the velocity and acceleration/deceleration of each individual leaf as well as the gap width. There was a slight decrease in the accuracy of leaf performance with increasing leaf speeds. The analysis results were presented through several graphs. The accuracy of the method was assessed as 0.01 mm for both the gap size and peak position determination.

Conclusions:

This study provides fast, easy, and accurate test methods for routine QA of the MLC performance and helps in faster troubleshooting of MLC problems in both IMRT and VMAT treatments.
Using computer building modeling and auralization as teaching tools
Authors: Coffeen Robert C.
Published: September 2012

Acoustic building modeling in computer programs is very useful in the understanding of room acoustics for venues of various types by architecture and architectural engineering students. Models provide calculation of reverberation time using the Sabine and similar equations as interior materials are changed. Ray tracing can be used to understand the effect of disturbing sound reflections from interior surface shapes and locations. Being able to create impulse responses in a model allows the estimation of reverberation time using Schroeder integration. And, transferring impulse responses to a measurement and analysis program allows determination of early decay time as well as T10, T20, T30 and other sound decay cutoff times. In addition, more advanced students can determine Sound Transmission Class STI, Strength G, Inter-aural Cross Correlation Coefficient IACC, and other acoustic parameters. But, one of the most useful items that can be produced by model impulse responses is auralization. This allows students to hear a simulation of room sound as reverberation time and other acoustic parameters are changed. Examples of using one of the several modeling and analysis programs will be presented.
Education technology in architectural acoustics: A hands-on program for teaching
Authors: Philipp Norman H.
Published: September 2012

Through the implementation of educational technology a web-based educational tool is being developed to aide in the teaching of architectural acoustics to architecture students at the undergraduate and graduate level. As the first step, its scope has been limited to reverberation time in architectural acoustics. The overall objective is to provide a dynamic educational tool for both educators and students to improve their understanding and retention of the principles of architectural acoustics.
Parallelized finite difference time domain room acoustic simulation
Authors: Fackler Cameron , Botts Jonathan , Xiang Ning
Published: September 2012

A parallelized room acoustics simulator based on the finite difference time domain (FDTD) method is developed, utilizing a Blue Gene/L supercomputer. Wave-based methods such as FDTD are desirable for use in room acoustics simulations since they account for effects such as diffraction and interference. However, such methods require large amounts of computational power and memory, especially when simulating large volumes or high frequencies. To utilize the power of modern computing systems and move toward large-scale simulations of realistic concert halls, a parallel FDTD implementation is written in the C++ programming language with the Message Passing Interface (MPI) library. The volume to be simulated is partitioned into blocks, which efficiently update shared interfaces between nearest neighbors using the Blue Gene architecture's point-to-point communication network. Several compact explicit FDTD schemes are compared using simulations of various spatial volumes, executed on varying numbers of processors. The use of a Blue Gene/L supercomputer demonstrates substantial speedup over an equivalent serial implementation.
Acoustic simulation of the church of San Francesco della Vigna
Authors: Boren Braxton B. , Longair Malcolm
Published: September 2012

San Francesco della Vigna is the oldest church in Venice for which there is evidence that acoustic considerations were taken into account in the architectural design. Francesco Zorzi, a humanist scholar, recommended that the church have a flat wooden coffered ceiling to improve the intelligibility of the sermons preached there. But instead of Zorzi’s recommended flat ceiling, the church was built with a plaster vault ceiling. Using measured acoustic data from the CAMERA project, a virtual model of the church was constructed in Odeon whose simulated parameters matched the measured values at different source-receiver combinations. After obtaining a good match to the measured values, this virtual model was then altered to reconstruct the flat ceiling recommended by Zorzi. This ceiling was then placed at the two different heights at which it might have been built in Zorzi’s time. The simulations show that the more absorptive ceiling might have slightly reduced the long reverberation time in the church. However, the ceiling would have been too high to make any significant change in the D50, which still remains extremely low. Thus this simulation indicates that Zorzi’s ceiling would not have made the impact on speech intelligibility he had expected.
C.S.Clay: A distinguished acoustician
Authors: Tolstoy Ivan
Published: September 2012

Clay’s well-known work in ocean acoustics earned him an international reputation. His contributions ranged from studies of sound propagation in shallow water to the application of filter theory in noisy environments, diffraction from rough surfaces, sound scatter by fish and, generally speaking, the execution and design of numerous experiments. Less well known, perhaps on account of his modesty, was his role at Columbia University’s Hudson labs in designing a fully digitized microphone array for the study of low frequency atmospheric waves (in the 1 to 600 sec. period band), which led to the detection of gravity and acoustic-gravity waves from several nuclear tests. After leaving Columbia, Clay accepted a professorship at the University of Wisconsin where, among other things, he taught geophysics and continued research on sound scatter. His presence and participation at Acoustical Society meetings will be sorely missed.
C.S. Clay—A scientist of outstanding vision, brilliance, and versatility
Authors: Feuillade Christopher
Published: September 2012

During a scientific career of more that 60 years, Clarence Clay made many important research contributions spanning a wide range of topics in ocean acoustics, acoustical oceanography, geophysical exploration, signal processing, SONAR system applications and techniques, and more. His achievements are detailed in over 135 peer-reviewed articles, abstracts, technical reports, and at least five patents. In addition he was the author, or co-author, of four widely read textbooks. His research work is recognized internationally for the far-reaching significance of many of the advances he made. In order to attempt a proper appreciation of the range and versatility of Clay’s accomplishments, within the constraints of a 30 minute presentation, this talk will consist of a series of brief overviews of a representative selection of topics on which he worked. These include: the theory and measurement of rough surface scattering, particularly at the ocean boundaries; matched-filter signal transmission and detection, time reversal, and matched-field processing; acoustic methods and models for scattering from individual fish, and for fish detection and abundance estimation; the theory and experimental investigation of time domain scattering from wedges, and its incorporation into wedge assemblage models; and the theory and applications of seismic exploration and profiling.
A review of Clarence Clay's research contributions in the area of fisheries acoustics
Authors: Ehrenberg John
Published: September 2012

This presentation provides an overview of the significant contribution that Clay and his students made to the understanding of the statistical nature of the acoustic signals scattered from fish and the methods for removing the effect of the beam pattern from the received echo statistics to measure the underlying fish backscattering statistics. By making measurements of the acoustic scattering from live fish, he showed that the probability density function of the envelope amplitude of the echo signal scattered from the fish could be modeled by a Ricean PDF. He further showed that as the ratio of the length of the fish to the acoustic wavelength became large, the PDF became Rayleigh distributed. Clay and his students were interested in using the measured echo statistics to obtain information about the size distribution of the fish producing the scattering. They developed a method for deconvolving the effect of the acoustic beam pattern from the received echo statistics to provide an estimate of the fish scattering PDF. The effectiveness of the technique was demonstrated for a fish population in a Wisconsin lake.
Ice cream and the application of backscatter models
Authors: Horne John K.
Published: September 2012

I was invited to visit Clay and colleagues at the Center for Limnology at the University of Wisconsin, Madison in October 1991. As an acoustics neophyte, I had lots of questions that Clay patiently took the time to answer while we ate ice cream at the Memorial Union. That discussion led to the development of the Kirchhoff Ray-mode (KRM) model and increased the use of acoustic scattering models to investigate how fish reflect sound. Acoustic scattering models enable investigation of factors or conditions that cannot be replicated or isolated in field or experimental measures. The iterative combination of models with measures improves accuracy of model predictions and the understanding of how the physics of sound interacts with biology to produce acoustic data. Both the structure and application of backscatter models have evolved in their complexity and realism. Examples will be used to illustrate advances in and insight gained through modeling, with special consideration of Clay’s contributions. The talk will conclude with speculation on what Clay would see as the next step.