bluuebunny/crossref_metadata_2025 huggingface dataset:
Advances in stroke prevention
Authors: Sherzai Ayesha Z. , Elkind Mitchell S.V.
Published: March 2015

Stroke remains to be a leading cause of disability. However, optimal strategies can prevent up to 80% of strokes. A large body of evidence supports many strategies for primary and secondary prevention of stroke. The purpose of this paper is to highlight recent major advances for management of modifiable medical and behavioral risk factors of stroke. Specific studies are highlighted, including those related to atrial fibrillation (AF), hypertension, revascularization, hyperlipidemia, antiplatelets, smoking, diet, and physical activity. Effective strategies include the use of novel oral anticoagulants for AF, antiplatelet therapy, and intensive lowering of atherosclerosis risk factors.
Differential effects of two probiotics on the risks of eczema and atopy associated with single nucleotide polymorphisms to Toll‐like receptors
Authors: Marlow Gareth , Han Dug Yeo , Wickens Kristin , Stanley Thorsten , Crane Julian , Mitchell Edwin A. , Dekker James , Barthow Christine , Fitzharris Penny , Ferguson Lynnette R. , Morgan Angharad R.
Published: March 2015

Background

There is strong evidence to support a genetic predisposition to eczema and more recently studies have suggested that probiotics might be used to prevent eczema by modifying the expression of putative allergy‐associated genes. The aim of this present study was to investigate whether two probiotics, Lactobacillus rhamnosus HN001 (HN001) and Bifidobacterium animalis subsp. lactis HN019 (HN019), can modify the known genetic predisposition to eczema conferred by genetic variation in the Toll‐like receptor (TLR) genes in a high‐risk infant population.

Methods

We selected 54 SNPs in the Toll‐like receptor genes. These SNPs were analysed in 331 children of sole European ancestry as part of a double‐blind, randomized, placebo‐controlled trial examining the effects of HN001 and HN019 supplementation on eczema development and atopic sensitization.

Results

The data showed that 26 TLR SNPs interacted with HN001 resulting in a significantly reduced risk of eczema, 18 for eczema severity as defined by SCORAD ≥10 and 20 for atopic sensitization compared to placebo. There were only two SNPs that interacted with HN019 resulting in a reduced risk of eczema, eczema severity or atopy.

Conclusions

This is the first study to show that the negative impact of specific TLR genotypes may be positively affected by probiotic supplementation. HN001 exhibits a much stronger effect than HN019 in this respect.
New ammonoid taxa from theLowerCretaceousGiumalFormation of theTethyanHimalaya (NorthernIndia)
Authors: Lukeneder Alexander , Suttner Thomas J. , Bertle Rufus J.
Published: March 2015

Knowledge of theEarlyCretaceous ammonoids of theNW‐Himalayas was poor until recent discoveries. Intense sampling from theGiumalFormation exposed near the village ofChikkim (SpitiValley,HimachalPradesh,India) led to the recognition of a newEarlyCretaceous ammonoid fauna. The succession consists of arenitic sandstone interbedded with shale that was deposited by turbidity currents on an unstable shelf in theEarlyCretaceous. Ammonoids have been obtained only from sandstone beds in the lower one‐third and close to the top of thec. 350‐m‐thick section. Eight new ammonoid taxa (1 genus and 7 species) are described:Sinzovia frankisp. nov. (rare),Giumaliceras giumaliensegen. et sp. nov. (abundant),Giumaliceras bhargavaigen. et sp. nov. (rare),Neocomites(Eristavites)platycostatiformissp. nov. (rare),Cleoniceras oberhauserisp. nov. (abundant),Australiceras himalayensesp. nov. (rare) andDeshayesites fuchsisp. nov. (rare).SinzoviaandDeshayesitesare reported for the first time from theTethyanHimalaya. According to the biostratigraphic relevance of some ammonoid taxa described here, the age of theGiumalFormation can be constrained fromBerriasian (Giumalicerasassemblage) toAptian (Cleonicerasassemblage). The discovery of the new fauna substantiates the significance of theGiumalFormation aroundChikkim and facilitates comparison with faunal assemblages from other regions in theTethysOcean and beyond.
The earliest known strophomenoids (Brachiopoda) from early Middle Ordovician rocks Of South China
Authors: Renbin Zhan , Jisuo Jin , Jiayu Rong , Yan Liang
Published: March 2015

The upper Daguanshan Formation (middle Expansograptus hirundo graptolite biozone, Dapingian, early Middle Ordovician) of the Shuanghe area, Changning County, southern Sichuan Province, contains three new genera and species of strophomenoids: Ochyromena plana, Shuangheella elongata, and Primotimena globula, which are attributed to the Strophomenidae, Rafinesquinidae and Glyptomenidae respectively. These are the earliest known strophomenoids from the South China palaeoplate, and also the oldest rafinesquinid and glyptomenid brachiopods worldwide. Global review of the superfamily Strophomenoidea of Middle Ordovician age suggests that the first diversity peak at the species level occurred in late Darriwilian (Llanvirn) time, mainly as a result of the rapid diversification of the family Strophomenidae. The first appearance datum (FAD) of strophomenoids and their possible westward dispersal were from North China (latest Floian) and/or South China (early Dapingian), through the Chu‐Ili terrane of Kazakhstan, Iran, and Baltica (early Darriwilian), to Avalonia and Laurentia (late Darriwilian). This points to the existence of early diversification hotspots of the strophomenoid superfamily in the North and South China palaeoplates during the early Middle Ordovician in generally shallow water (corresponding to BA2) environments. The high degree of similarity in the external morphology and ventral interior of the three new genera indicates that the early diversification of strophomenoids began with differentiation of the cardinalia, especially in the configuration of the bilobed cardinal process, a key evolutionary novelty for the strophomenoids.
Identification of a diverse mini‐core panel of Indian rice germplasm based on genotyping using microsatellite markers
Authors: Tiwari Kapil K. , Singh Anshuman , Pattnaik Sasmita , Sandhu Maninder , Kaur Sukhdeep , Jain Sourabh , Tiwari Sushma , Mehrotra Shweta , Anumalla Mahender , Samal Rashmita , Bhardwaj Jyoti , Dubey Neha , Sahu Vikrant , Kharshing Gayle A. , Zeliang Patu K. , Sreenivasan Kadiri , Kumar Pankaj , Parida Swarup K. , Mithra Sevanthi V. A. , Rai Vandana , Tyagi Wricha , Agrawal Pawan K. , Rao Atmakuri R. , Pattanayak Arunava , Chandel Girish , Singh Ashok K. , Bisht Ishwari S. , Bhat Kangila V. , Rao Gundimeda J. N. , Khurana Jitendra P. , Singh Nagendra K. , Mohapatra Trilochan
Published: March 2015

Identification of a small core germplasm set representing the available genetic diversity is essential for its proper evaluation and subsequent utilization in rice improvement programmes. For constituting a small diverse mini‐core panel of Indian rice germplasm, a representative set of 6912 accessions drawn based on their geographic origin from the whole rice germplasm collection available in the National Gene Bank was genotyped using 36 microsatellite markers. Automated fragment analysis of amplicons yielded a total of 435 alleles, with an average 12.4 and range of 3–29 alleles per locus. Polymorphism information content (PIC) ranged from 0.08 (RGNMS190) to 0.86 (RM552) with an average of 0.528. Based on genotyping data, a mini‐core consisting of 98 genotypes was identified. Ninety‐four per cent of the alleles present in the core set were present in the mini‐core. The identified small but diverse panel will be useful for further intensive trait‐specific evaluation and utilization in allele mining.
Detecting major QTL associated with resistance to bacterial blight using a set of rice reciprocal introgression lines with high density SNP markers
Authors: Zhang Fan , Xie Xuewen , Xu Meirong , Wang Wensheng , Xu Jianlong , Zhou Yongli , Li Zhikang
Published: March 2015

Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is a worldwide rice disease. QTL providing BB resistance were identified using a set of introgression lines (ILs) derived from a cross between Teqing and Lemont, and 3924 evenly distributed SNP markers developed from the two parents. After inoculating three Xoo pathotypes, CII, CIV and CV, seven major BB resistance‐associated QTL were detected. The alleles at all loci with improved BB resistance were from the Teqing background. Four QTL resistance to CII and CIV were identified in the reciprocal backgrounds across 2 years. Six QTL conferring resistance to CV identified in Teqing background were not detected in Lemont background, indicating that genetic background had a strong effect on the BB resistance‐associated QTL. Based on the interactions of 27 significant digenic QTL pairs among the seven main‐effect QTL, the QTL were divided into three strain‐specific groups. Genotype analyses of resistant ILs suggest that rice lines with a high level of resistance to BB can be achieved by pyramiding R gene(s) and QTL that interact with R gene(s).
Executive dysfunction assessed by Clock‐Drawing Test in older non‐demented subjects with metabolic syndrome is not mediated by white matter lesions
Authors: Viscogliosi Giovanni , Chiriac Iulia Maria , Andreozzi Paola , Ettorre Evaristo
Published: March 2015

Aims

Metabolic syndrome (MetS) has been associated with greater occurrence of white matter hyperintensities (WMH). It remains uncertain whether MetS as a construct is associated with poorer cognitive performances. This study explores whether MetS is associated with poorer performances in global and domain‐specific cognitive tests in older non‐demented subjects independently of its individual components, WMH severity and other variables.

Methods

MetS was diagnosed according to the National Cholesterol Education Program Adult Treatment Panel III definition. Brain magnetic resonance studies (1.5T) were performed. Deep and periventricular WMH were graded using the Fazekas scale. Subjects underwent the Mini‐Mental State Examination, the Babcock Short Story Recall test and the Clock‐Drawing Test (CDT).

Results

Eighty community‐dwellers aged 67–91 years were studied. Subjects with MetS (n = 35) had more severe WMH, and poorer performances on the CDT (P = 0.003) and the Babcock Short Story Recall test (P = 0.027). After multiple adjustment, MetS was inversely associated with CDT scores (B = −1.285; 95% confidence interval = −1.996–−0.575; P = 0.001) but not with episodic memory. Results were not affected by WMH severity. Interestingly, none of the individual components of MetS predicted poorer cognitive performances.

Conclusions

Impairment in executive functions assessed by CDT may represent an early and specific sign of cognitive decline in older individuals with MetS. Future longitudinal studies are needed to better establish the predictive role of MetS on dementia and to demonstrate the possibility of dementia prevention by targeting MetS.
Isotretinoin and Vitiligo: Can Chronic Cheilitis Cause Koebnerization?
Authors: Garner Michael L. , McShane Diana B. , Burkhart Craig N. , Morrell Dean S.
Published: March 2015

Vitiligo after trauma through koebnerization is a widely reported phenomenon. Herein we present a case of vitiligo in an area of chronic cheilitis after isotretinoin treatment.
Acrodermatitis Enteropathica: A Novel SLC39A4 Gene Mutation in a Patient with Normal Zinc Levels
Authors: Garza‐Rodríguez Verónica , de la Fuente‐García Alberto , Liy‐Wong Carmen , Küry Sébastien , Schmitt Sébastien , Jamall Ijaz S. , Ocampo‐Candiani Jorge
Published: March 2015

Acrodermatitis enteropathica (AE) is a rare disease that results from a defective gene, SLC39A4, and is characterized by dermatitis, alopecia, and diarrhea. We report a case of AE presenting with only periorificial and acral dermatitis in which genetic testing revealed two novel compound heterozygous missense mutations for SLC39A4. This case demonstrates that not all AE mutations alter zinc transporters in the same manner and highlights the phenotypic variability of AE.
Basal Cell Carcinoma After Treatment of Childhood Acute Lymphoblastic Leukemia and Concise Review of the Literature
Authors: Unal Sule , Cetin Mualla , Gumruk Fatma
Published: March 2015

Basal cell carcinoma (BCC) is a rare secondary malignancy which may occur more often in children with acute lymphoblastic leukemia (ALL) who have previously received radiation therapy compared to to those who received no radiation.
Tuberous Sclerosis Complex: An Update for Dermatologists
Authors: Jacks Stephanie K. , Witman Patricia M.
Published: March 2015

Tuberous sclerosis complex is an autosomal dominant disorder that often manifests early in life with cutaneous features, and it is important that dermatologists who care for children remain up to date on its diagnosis and management. This article provides an update regarding the most recent guidelines for diagnosis published by the International Tuberous Sclerosis Complex Consensus Conference, which took place in 2012, and provides a brief literature review of the most recent developments in the treatment of skin findings.
Affective Social Competence and Teacher–child Relationship Quality: Race/Ethnicity and Family Income Level as Moderators
Authors: Garner Pamela W. , Mahatmya Duhita
Published: March 2015

This study examined whether race/ethnicity and family income level moderated associations between children's affective social competence and teacher–child relationships among 132 Black, White, and Latino preschoolers. Boys and girls were equally represented in the sample. Of the three racial/ethnic groups, Latino children scored lowest on emotion regulation, were less close to their teachers, and experienced more teacher–child conflict and dependence. In contrast, Black children had closer, less conflict‐laden, and less dependent teacher–child relationships than children of other racial/ethnic backgrounds. Emotion regulation served as a protective factor against problematic teacher–child relationships, particularly for Latino and Black children compared with high‐income White children. Emotion regulation was positively associated with teacher–child closeness for Black children. However, it was negatively associated with teacher–child conflict for Latino children, regardless of income. For all outcomes, teacher characteristics accounted highly for the differences in teacher–child relational quality. Findings are discussed in terms of the functional role of emotions for teacher–child relationships and suggest important contextual influences on the associations.
Combination therapy – deferasirox and deferoxamine – in thalassemia major patients in emerging countries with limited resources
Authors: Arandi N. , Haghpanah S. , Safaei S. , Zahedi Z. , Ashrafi A. , Eatemadfar P. , Zarei T. , Radwan A. H , Taher A. T , Karimi M.
Published: March 2015

Background

The problem of iron‐overload observed in thalassemia patients can be overcome using chelating agents such as deferiprone (Ferroprox®), deferasirox (Exjade®) and deferoxamine (Desferal®). Although these drugs can be used as monotherapy, combined therapy, especially deferiprone with deferoxamine, has led to promising outcomes in various studies.

Methods and Materials

In this quasi‐experimental study, serum ferritin levels were evaluated in 32 β‐thalassemia major patients with severe iron overload before and after receiving combined deferasirox (30–40 mg kg−1 day−1) and deferoxamine (40–50 mg kg−1 day−1) 2 days a week. This study was conducted from September 2012 to September 2013 in Southern Iran.

Results

The mean of serum ferritin levels significantly reduced from 4031 ± 1955 to 2416 ± 1653 ng mL−1 after 12 months of therapy (P < 0·001). Echocardiograph findings showed significant improvement 1year after end of the study (P < 0·001). No drug toxicity was observed by monitoring serum creatinine, liver enzymes and blood urea nitrogen (BUN) during the study period. We observed no correlation between mean serum ferritin change and age (P = 0·87). In addition, the mean serum ferritin change did not differ between male and female thalassemia patients (P = 0·454). No difference in mean serum ferritin change was observed between patients who had undergone splenectomy compared to those who had not done so (P = 0·307).

Conclusion

The study suggests that combination chelating therapy with deferasirox and deferoxamine can effectively reduce iron burden in β‐thalassemia major patients with heavy iron overload without any significant complications.
Histone H2A/H2B chaperones: from molecules to chromatin‐based functions in plant growth and development
Authors: Zhou Wangbin , Zhu Yan , Dong Aiwu , Shen Wen‐Hui
Published: March 2015

Nucleosomal core histones (H2A, H2B, H3 and H4) must be assembled, replaced or exchanged to preserve or modify chromatin organization and function according to cellular needs. Histone chaperones escort histones, and play key functions during nucleosome assembly/disassembly and in nucleosome structure configuration. Because of their location at the periphery of nucleosome, histone H2A–H2B dimers are remarkably dynamic. Here we focus on plant histone H2A/H2B chaperones, particularly members of the NUCLEOSOME ASSEMBLY PROTEIN‐1 (NAP1) and FACILITATES CHROMATIN TRANSCRIPTION (FACT) families, discussing their molecular features, properties, regulation and function. Covalent histone modifications (e.g. ubiquitination, phosphorylation, methylation, acetylation) and H2A variants (H2A.Z, H2A.X and H2A.W) are also discussed in view of their crucial importance in modulating nucleosome organization and function. We further discuss roles of NAP1 and FACT in chromatin‐based processes, such as transcription, DNA replication and repair. Specific functions of NAP1 and FACT are evident when their roles are considered with respect to regulation of plant growth and development and in plant responses to environmental stresses. Future major challenges remain in order to define in more detail the overlapping and specific roles of various members of the NAP1 family as well as differences and similarities between NAP1 and FACT family members, and to identify and characterize their partners as well as new families of chaperones to understand histone variant incorporation and chromatin target specificity.
Reduced Burden of Salmonella enterica in Bovine Subiliac Lymph Nodes Associated with Administration of a Direct‐fed Microbial
Authors: Vipham J. L. , Loneragan G. H. , Guillen L. M. , Brooks J. C. , Johnson B. J. , Pond A. , Pond N. , Brashears M. M.
Published: March 2015

Despite effective food safety interventions within abattoirs, Salmonella enterica remains a common contaminant of raw ground beef. Research has recently implicated peripheral lymph nodes (PLNs) as a potential route by which Salmonella contaminates ground beef. This study examined the efficacy of using Lactobacillus animalis (formerly designated Lactobacillus acidophilus; NP51) and Propionibacterium freudenreichii (NP24), at 109 cfu/head/day, as a direct‐fed microbial (DFM) in feedlot cattle diets to control Salmonella within PLNs. Two studies were conducted in which cattle were randomly allocated into either control or DFM treatment groups. Diets of treated cattle were supplemented with 109 cfu/head/day of the DFM, while control groups received no DFM supplementation. During slaughter at abattoirs, one subiliac lymph node (SLN) per carcass was collected from 627 carcasses from one study and 99 carcasses from the second study. Lymph nodes were cultured to estimate the presence and concentration of Salmonella. In the first study, effects of DFM supplementation varied across slaughter days. On the first and second slaughter days, prevalence was reduced by 50% (P = 0.0072) and 31% (P = 0.0093), respectively. No significant difference was observed on slaughter day three (P = 0.1766). In the second study, Salmonella was 82% less likely (P = 0.008) to be recovered from SLNs of treatment cattle. While a greater relative risk reduction was observed in the latter study, absolute risk reductions were similar across studies. A significant reduction in the concentration of Salmonella in SLNs (P < 0.0001) on a cfu/g and cfu/node basis was also observed in cattle administered NP51 and NP24 in the first study; in the second study, too few quantifiable SLNs were observed to facilitate meaningful comparisons. The results indicate that NP51 and NP24 supplementation may aid in reducing the prevalence and concentration of Salmonella in SLNs and, therefore, serve as an effective control measure to reduce Salmonella in ground beef products.
The Internal Flow Field and Overall Performance of a Centrifugal Fan Impeller: Experiment and Prediction
Authors: Wright T. , Tzou K. T. S. , Greaves K. W. , Madhavan S.
Published: March 2015

Analytical and experimental procedures for determining the detailed internal flow behavior in the impeller of a centrifugal fan are presented. Predicted and measured values of both the detailed flow fields and overall performance of the impeller are shown to be in good agreement. The analytical procedures are based on a finite element method to predict the inviscid flow field, coupled to a semi-empirical determination of pressure losses in the impeller based on boundary layer calculations. The experimental work used to validate these predictions uses extensive surface pressure taps in the rotating impeller as well as information from inlet and discharge velocity traverses to determine overall performance. The purpose of this work is the development of accurate and reliable analytical tools for the design of air and gas moving equipment with improved performance and efficiency for the power utility market and heavy industrial applications.
Rotary Turbine Stage Moisture Separators
Authors: Povarov O. A.
Published: March 2015

This paper deals with new moisture removal methods in wet vapor turbines of nuclear power stations: moisture separation effectiveness of turbine stages, and separators with freely rotating moving wheels. The stage moisture separators may be installed in the turbines of nuclear power stations; other applications include: the gas, chemical, and other branches of industry.
A Computer Model for Gas Turbine Blade Cooling Analysis
Authors: Han J. C. , Ortman D. W. , Lee C. P.
Published: March 2015

A computer model for gas turbine blade cooling analysis has been developed. The finite difference technique over the chord and span of the blade is employed. A flow balance and an energy balance program are included in the model. The model is capable of predicting cooling flow characteristics (mass flow rate and internal pressure distribution) and metal temperature profiles of multipass coolant passages in rotating blades with local film cooling. The paper first presents the analytical model of coolant flow and heat transfer, then the computer program is discussed. Finally, the computed results of a sample blade at engine conditions is presented and discussed.
The Application of Adiabatic Film Cooling Effectiveness to Non-Adiabatic Blade Cooling Design
Authors: Lee C. P. , Han J. C.
Published: March 2015

The effect of heat transfer on film cooling has been studied analytically. The proposed model shows that the non-adiabatic film cooling effectiveness will increase with increasing of the heat transfer parameter, Ū / (ρVCp)2, on the convex, the flat and the concave walls over the entire range of film cooling parameter, X/MS. On the convex wall with a blowing rate, M, of 0.51 and a heat transfer parameter of 10−3 at the typical engine conditions, the non-adiabatic effectiveness can be higher than the adiabatic effectiveness by 45% at a film cooling parameter of 103; while the film temperature can be lower than the adiabatic wall by 18°C (32°F) at a dimensionless distance of 500. The model can be extended and applied to the heat transfer analysis for any kind of turbine blade with film cooling.
Inlet Flow Distortions in Centrifugal Fans
Authors: Madhavan S. , DiRe J. , Wright T.
Published: March 2015

Recent measurements of the performance of a centrifugal fan subjected to inlet flow distortion are presented. Results of axial and multilobed distortion modes are discussed in the context of a previously published study to provide a more comprehensive evaluation of related fan performance degradation. Distortion parameters presented in the previous study are shown to be insufficient for the complete description of inlet distortion and further indicators are proposed.
Combustion of a Coal-Water Mixture in a Gas Turbine Combustor
Authors: Horner M. W.
Published: March 2015

An experimental program is under way to evaluate the atomization, combustion, turbine blading tolerance, and emissions for a coal-water mixture (CWM) fuel. Combustor and turbine components from an MS6001 commercial gas turbine are being utilized with modifications to accommodate the CWM characteristics. Raw coal is physically cleaned, or beneficiated, to achieve less than 1% ash; this cleaned coal is then treated to achieve acceptable viscosity and stability as a 50/50 mixture by weight with water.

The preparations for combustion testing have been completed, and testing with CWM has begun. The goals of the test are to achieve combustion at 100% CWM and to prepare for subsequent ash deposition testing with a downstream turbine nozzle cascade sector. Modifications to operating procedures and physical geometry will be made, as necessary, to achieve acceptable component metal temperatures, pressure pulsation levels, and combustor exit spatial temperature variations.
Utility Applications of Pressurized Fluid-Bed Combustion Systems
Authors: Byam John W. , Grieve Richard M.
Published: March 2015

The IEA-Grimethorpe pressurized fluid-bed (PFB) pilot plant has recently completed 3,600 hours of testing, the results of which provide valuable design information for the commercial application of PFB systems to utility applications. This paper presents the particular results of the Grimethorpe tests which relate to the design needs of coal-fired power plants and an assessment of the impact on plant design. The application of results to the construction of new and retrofit power plants is discussed. Also discussed are those aspects of the Grimethorpe results which impact the economics of advanced coal-fired power plant operations.
Power Generation Through Coal Gasification: An Overview of DOE-Funded Projects
Authors: Halow J. S.
Published: March 2015

The U.S. Department of Energy is currently sponsoring a variety of projects aimed at developing advanced systems for power generation using coal gasification as the central conversion process. These systems include both gas turbines and fuel cells as power generating devices and emphasize hot gas cleanup for equipment protection and environmental control from coal contaminants.

Gasification projects in the DOE program cover a range of scales from laboratory investigations to PDU scale plants. Fundamental studies of gasification reactions, ash chemistry, transport processes, and modeling are being conducted to uncover potential improvements that may be made to gasification processes and to ways of reducing cleanup burdens on downstream equipment. Several PDU scale projects are being sponsored to further promising processes. Gas stream cleanup emphasize hot control of particulates, sulfur, alkali, and trace species which may damage power generation equipment. A systems approach has been adopted in formulating strategies for these programs. This approach and brief description of projects in gasification and cleanup will be presented.
Dynamic 31P MR spectroscopy of plantar flexion: Influence of ergometer design, magnetic field strength (3 and 7 T), and RF‐coil design
Authors: Šedivý Petr , Christina Kipfelsberger Monika , Dezortová Monika , Krššák Martin , Drobný Miloslav , Chmelík Marek , Rydlo Jan , Trattnig Siegfried , Hájek Milan , Valkovič Ladislav
Published: March 2015

Purpose:

Dynamic phosphorus magnetic resonance spectroscopy (31P MRS) during and after acute exercise enables the noninvasive in vivo determination of the mitochondrial capacity of skeletal muscle. Nevertheless, the lack of standardization in experimental setups leads to significant variations in published values of maximal aerobic capacity, even in the population of healthy volunteers. Thus, in this study, we aimed to assess the impact of the ergometer type (pneumatic and mechanical resistance construction), radiofrequency (RF)‐coil diameter, and different magnetic field strengths (3 and 7 T) on the metabolic parameters measured by dynamic 31P MRS during a plantar flexion isotonic exercise protocol within the same group of healthy volunteers.

Methods:

Dynamic 31P MRS measurements of the calf muscle in 11 volunteers (mean age, 36  ±  13 yrs; mean BMI, 23.5 ± 2.5 kg/m2), on a 3 T MR system with a custom‐made mechanical ergometer in the first research laboratory (RL1) and on 3 and 7 T MR systems equipped with a commercial pneumatic ergometer in the second research laboratory (RL2), were performed at three different workloads. RF‐coils differed slightly between the sites and MR systems used. The repeatability of the experimental protocol was tested in every setup. The basal concentrations of phosphocreatine (PCr), exercise‐induced depletion of PCr (ΔPCr), initial PCr resynthesis rate (VPCr), and mitochondrial capacity (Qmax) were calculated and compared between the research sites and field strengths.

Results:

High repeatability of the measurement protocol was found in every experimental setup. No significant differences at any workload were found in these metabolic parameters assessed at different magnetic field strengths (3 T vs 7 T), using the same ergometer (in RL2) and a similar RF‐coil. In the inter‐research laboratory comparison at the same field strength (3 T), but with using different ergometers and RF‐coils, differences were found in the concentration of PCr measured at rest and in the drop in PCr signal intensity. These differences translated into difference in the value of mitochondrial capacity at a workload of 15% of maximal voluntary contraction (MVC) force (0.45 ± 0.16 mM/s vs 0.31 ± 0.08 mM/s, in the RL1 and RL2, respectively).

Conclusions:

Metabolic parameters measured during exercise challenge by dynamic 31P MRS do not depend upon the magnetic field strength used. For multicenter studies with different ergometers, it is important to set the same workload, measurement, and evaluation protocols, especially when the effects of very mild exercise (15% MVC) are to be compared. However, a higher workload (24% MVC) decreases the influence of imperfections and intersite differences for the assessed value of maximal mitochondrial capacity.
Analyzing patterns in experts' approaches to solving experimental problems
Authors: Čančula Maja Poklinek , Planinšič Gorazd , Etkina Eugenia
Published: March 2015

We report detailed observations of three pairs of expert scientists and a pair of advanced undergraduate students solving an experimental optics problem. Using a new method (“transition graphs”) of visualizing sequences of logical steps, we were able to compare the groups and identify patterns that could not be found using previously existing methods. While the problem solving of undergraduates significantly differed from that of experts at the beginning of the process, it gradually became more similar to the expert problem solving. We mapped problem solving steps and their sequence to the elements of an approach to teaching and learning physics called Investigative Science Learning Environment (ISLE), and we speculate that the ISLE educational framework closely represents the actual work of physicists.
Dynamic time warping and sparse representation classification for birdsong phrase classification using limited training data
Authors: Tan Lee N. , Alwan Abeer , Kossan George , Cody Martin L. , Taylor Charles E.
Published: March 2015

Annotation of phrases in birdsongs can be helpful to behavioral and population studies. To reduce the need for manual annotation, an automated birdsong phrase classification algorithm for limited data is developed. Limited data occur because of limited recordings or the existence of rare phrases. In this paper, classification of up to 81 phrase classes of Cassin's Vireo is performed using one to five training samples per class. The algorithm involves dynamic time warping (DTW) and two passes of sparse representation (SR) classification. DTW improves the similarity between training and test phrases from the same class in the presence of individual bird differences and phrase segmentation inconsistencies. The SR classifier works by finding a sparse linear combination of training feature vectors from all classes that best approximates the test feature vector. When the class decisions from DTW and the first pass SR classification are different, SR classification is repeated using training samples from these two conflicting classes. Compared to DTW, support vector machines, and an SR classifier without DTW, the proposed classifier achieves the highest classification accuracies of 94% and 89% on manually segmented and automatically segmented phrases, respectively, from unseen Cassin's Vireo individuals, using five training samples per class.
Auditory brainstem response of the Japanese house bat (Pipistrellus abramus)
Authors: Boku Shokei , Riquimaroux Hiroshi , Simmons Andrea Megela , Simmons James A.
Published: March 2015

Auditory brainstem responses (ABR) to high frequencies encompassing the species' vocal repertoire were recorded from the inferior colliculus of the Japanese house bat, Pipistrellus abramus. Amplitudes of tone pips were systematically decreased to obtain a threshold of response at different tone frequencies. The compiled audiogram has a broad U-shape over the frequency range from 4 to 80 kHz, with low thresholds between 20 and 50 kHz. The most sensitive frequency region of 35–50 kHz occurs at the quasi-constant-frequency terminal portion of the bat's downsweeping frequency-modulated echolocation pulses. Good sensitivity extending down to 20 kHz includes the frequency range of the first harmonic of communication sounds. The ABR audiogram does not show distinct, narrow peaks of greater sensitivity at the dominant frequencies in species vocalizations. Latencies of peaks in ABR responses lengthened as stimuli were attenuated. At 40 kHz, response latencies traded with amplitude by −7 to −9 μs/dB, a value smaller than measured in another frequency-modulated bat using lower frequencies for echolocation. These results have implications for understanding the significance of amplitude-latency trading in a comparative context.
Nonlinear attenuation and dispersion in human calcaneus in vitro: Statistical validation and relationships to microarchitecture
Authors: Wear Keith A.
Published: March 2015

Through-transmission measurements were performed on 30 human calcaneus samples in vitro. Nonlinear attenuation and dispersion measurements were investigated by estimating 95% confidence intervals of coefficients of polynomial expansions of log magnitude and phase of transmission coefficients. Bone mineral density (BMD) was measured with dual x-ray absorptiometry. Microarchitecture was measured with microcomputed tomography. Statistically significant nonlinear attenuation and nonzero dispersion were confirmed for a clinical bandwidth of 300–750 kHz in 40%–43% of bone samples. The mean linear coefficient for attenuation was 10.3 dB/cm MHz [95% confidence interval (CI): 9.0–11.6 dB/cm MHz]. The mean quadratic coefficient for attenuation was 1.6 dB/cm MHz2 (95% CI: 0.4–2.8 dB/cm MHz2). Nonlinear attenuation provided little information regarding BMD or microarchitecture. The quadratic coefficient for phase (which is related to dispersion) showed moderate correlations with BMD (r = −0.65; 95% CI: −0.82 to −0.36), bone surface-to-volume ratio (r = 0.47; 95% CI: 0.12–0.72) and trabecular thickness (r = −0.40; 95% CI: −0.67 to −0.03). Dispersion was proportional to bone volume fraction raised to an exponent of 2.1 ± 0.2, which is similar to the value for parallel nylon-wire phantoms (2.4 ± 0.2) and supports a multiple-scattering model for dispersion.
Measurement with verification of stationary signals and noise in extremely quiet environments: Measuring below the noise floor
Authors: Ellingson Roger M. , Gallun Frederick J. , Bock Guillaume
Published: March 2015

It can be problematic to measure stationary acoustic sound pressure level in any environment when the target level approaches or lies below the minimum measureable sound pressure level of the measurement system itself. This minimum measureable level, referred to as the inherent measurement system noise floor, is generally established by noise emission characteristics of measurement system components such as microphones, preamplifiers, and other system circuitry. In this paper, methods are presented and shown accurate measuring stationary levels within 20 dB above and below this system noise floor. Methodology includes (1) measuring inherent measurement system noise, (2) subtractive energy based, inherent noise adjustment of levels affected by system noise floor, and (3) verifying accuracy of inherent noise adjustment technique. While generalizable to other purposes, the techniques presented here were specifically developed to quantify ambient noise levels in very quiet rooms used to evaluate free-field human hearing thresholds. Results obtained applying the methods to objectively measure and verify the ambient noise level in an extremely quiet room, using various measurement system noise floors and analysis bandwidths, are presented and discussed. The verified results demonstrate the adjustment method can accurately extend measurement range to 20 dB below the measurement system noise floor, and how measurement system frequency bandwidth can affect accuracy of reported noise levels.
The effect of exposure to a single vowel on talker normalization for vowels
Authors: Morton John R. , Sommers Mitchell S. , Lulich Steven M.
Published: March 2015

The current work investigated the role of single vowels in talker normalization. Following initial training to identify six talkers from the isolated vowel /i/, participants were asked to identify vowels in three different conditions. In the blocked-talker conditions, the vowels were blocked by talker. In the mixed-talker conditions, vowels from all six talkers were presented in random order. The precursor mixed-talker conditions were identical to the mixed-talker conditions except that participants were provided with either a sample vowel or just the written name of a talker before target-vowel presentation. In experiment 1, the precursor vowel was always spoken by the same talker as the target vowel. Identification accuracy did not differ significantly for the blocked and precursor mixed-talker conditions and both were better than the pure mixed-talker condition. In experiment 2, half of the trials had a precursor spoken by the same talker as the target and half had a different talker. For the same-talker precursor condition, the results replicated those in experiment 1. In the different-talker precursor, no benefit was observed relative to the pure-mixed condition. In experiment 3, only the written name was presented as a precursor and no benefits were observed relative to the pure-mixed condition.
A finite element model of the tuning slot of labial organ pipes
Authors: Rucz Péter , Augusztinovicz Fülöp , Angster Judit , Preukschat Tim , Miklós András
Published: March 2015

An acoustic model suitable for the characterization of tuning slots of labial organ pipes is presented in this paper. Since the tuning slot arrangement is similar (but not identical) to that of toneholes in woodwind instruments, the adaptability of the well-established tonehole model for the specific problem is examined. A numerical model utilizing the finite element (FE) and perfectly matched layer techniques is set up for the simulation of tuning slots with design parameters varying over a wide range. Analytical tonehole models and the proposed numerical tuning slot model are both combined with analytical one-dimensional waveguide models to predict the acoustic behavior of tuning slot pipes. Comparison to measurements carried out on experimental pipes proves that the hybrid waveguide/FE model can predict the most important properties of the tuning slot pipe with good accuracy. The finite element method (FEM) also overcomes the limitations of traditional tonehole models relying on the equivalent T-circuit approximation. By means of the FE model the eigenfrequency-structure and its impact on the character of the sound can be foretold in the design phase, by which a more efficient scaling of tuning slot pipes can be achieved.
Modeling guided elastic waves in generally anisotropic media using a spectral collocation method
Authors: Quintanilla F. Hernando , Lowe M. J. S. , Craster R. V.
Published: March 2015

Guided waves are now well established for some applications in the non-destructive evaluation of structures and offer potential for deployment in a vast array of other cases. For their development, it is important to have reliable and accurate information about the modes that propagate for particular waveguide structures. Essential information that informs choices of mode transducer, operating frequencies, and interpretation of signals, among other issues, is provided by the dispersion curves of different modes within various combinations of geometries and materials. In this paper a spectral collocation method is successfully used to handle the more complicated and realistic waveguide problems that are required in non-destructive evaluation; many pitfalls and limitations found in root-finding routines based on the partial wave method are overcome by using this approach. The general cases presented cover anisotropic homogeneous perfectly elastic materials in flat and cylindrical geometry. Non-destructive evaluation applications include complex waveguide structures, such as single or multi-layered fiber composites, lined, bonded and buried structures. For this reason, arbitrarily multi-layered systems with both solid and fluid layers are also addressed as well as the implementation of interface models of imperfect boundary conditions between layers.
Intrinsic and Extrinsic Contributions to Seated Balance in the Sagittal and Coronal Planes: Implications for Trunk Control After Spinal Cord Injury
Authors: Audu Musa L. , Triolo Ronald J.
Published: March 2015

The contributions of intrinsic (passive) and extrinsic (active) properties of the human trunk, in terms of the simultaneous actions about the hip and spinal joints, to the control of sagittal and coronal seated balance were examined. Able-bodied (ABD) and spinal-cord-injured (SCI) volunteers sat on a moving platform which underwent small amplitude perturbations in the anterior-posterior (AP) and medial-lateral (ML) directions while changes to trunk orientation were measured. A linear parametric model that related platform movement to trunk angle was fit to the experimental data by identifying model parameters in the time domain. The results showed that spinal cord injury leads to a systematic reduction in the extrinsic characteristics, while most of the intrinsic characteristics were rarely affected. In both SCI and ABD individuals, passive characteristics alone were not enough to maintain seated balance. Passive stiffness in the ML direction was almost 3 times that in the AP direction, making more extrinsic mechanisms necessary for balance in the latter direction. Proportional and derivative terms of the extrinsic model made the largest contribution to the overall output from the active system, implying that a simple proportional plus derivative (PD) controller structure will suffice for restoring seated balance after spinal cord injury.
The Effect of Isolated Hamstrings Fatigue on Landing and Cutting Mechanics
Authors: O’Connor Kristian M. , Johnson Carl , Benson Lauren C.
Published: March 2015

The function of the hamstrings in protecting the ACL is not fully understood. The purpose of this study was to determine how landing knee mechanics were affected by hamstrings fatigue, analyzed with principal components analysis (PCA). Knee joint mechanics were collected during single-leg stride landings that were followed by lateral and vertical jumps. An isokinetic fatigue protocol was employed to reduce hamstrings strength by 75% at the cessation of the exercise protocol. On the landing test day, participants performed the stride landing maneuvers before and after the fatigue protocol. PCA was performed on the landing knee joint angle, moment, and power waveforms, and MANOVAs were conducted on the retained PCs of each waveform (P < .05). On the strength test day, hamstrings strength recovery was assessed with an identical fatigue protocol followed by strength assessment ~75 s after the cessation of exercise. Pre- and postexercise hamstrings strength on this day was assessed with a dependent t test (P < .05). The hamstrings strength remained significantly reduced by ~8% postexercise (75 s). For stride landings followed by vertical jumps, there were significantly reduced knee flexion angles, extensor moments, and energy absorption. This was indicative of a stiffer landing strategy postfatigue, which has been associated with increased ACL loading.
Greater Step Widths Reduce Internal Knee Abduction Moments in Medial Compartment Knee Osteoarthritis Patients During Stair Ascent
Authors: Paquette Max R. , Klipple Gary , Zhang Songning
Published: March 2015

Increased step widths have been shown to reduce peak internal knee abduction moments in healthy individuals but not in knee osteoarthritis patients during stair descent. This study aimed to assess effects of increased step widths on peak knee abduction moments and associated variables in adults with medial knee osteoarthritis and healthy older adults during stair ascent. Thirteen healthy older adults and 13 medial knee osteoarthritis patients performed stair ascent using preferred, wide, and wider step widths. Three-dimensional kinematics and ground reaction forces (GRFs) using an instrumented staircase were collected. Increased step width reduced first and second peak knee abduction moments, and knee abduction moment impulse. In addition, frontal plane GRF at time of first and second peak knee abduction moment and lateral trunk lean at time of first peak knee abduction moment were reduced with increased step width during stair ascent in both groups. Knee abduction moment variables were not different between knee osteoarthritis patients and healthy controls. Our findings suggest that increasing step width may be an effective simple gait alteration to reduce knee abduction moment variables in both knee osteoarthritis and healthy adults during stair ascent. However, long term effects of increasing step width during stair ascent in knee osteoarthritis and healthy adults remain unknown.