bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen fertilization rate affects feeding, larval performance, and oviposition preference of the beet armyworm, Spodoptera exigua, on cotton
Authors: Chen Yigen , Ruberson John R. , Olson Dawn M.
Published: February 2008

Nitrogen (N) is one of the most critical chemical elements for plant and animal growth, exerting a variety of bottom‐up effects. Development and oviposition of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), were studied in relation to varying N fertilization levels (42, 112, 196, and 280 p.p.m.) in cotton [Gossypium hirsutum L. (Malvaceae)]. Low N fertilization of cotton plants led to reduced plant biomass and a lower percentage of N in leaf blades and in leaf petioles. Development of S. exigua larvae fed with plants with reduced N applications (42 and 112 p.p.m.) was prolonged relative to treatments receiving higher N fertilization. Almost all larvae reared on artificial diets underwent only five instars before pupation. However, most larvae reared on cotton plants, irrespective of N levels, experienced a supernumerary sixth larval instar. Furthermore, significantly more larvae reared on lower N cotton plants underwent supernumerary development compared to larvae reared on higher N cotton plants. Life‐time feeding damage per larva ranged from 55 to 65 cm2, depending on the nutritional quality of the food plant, although the differences were not statistically significant. Larvae distinguished between cotton plants with various nutritional qualities and fed preferentially on higher N plants. Female moth oviposition choice was also affected by host plant nutritional quality: cotton plants with higher N levels were preferentially chosen by S. exigua females for oviposition. The mechanisms of these effects are unclear, but they can have important implications for population dynamics and pest status of beet armyworms in the field.
The pattern and prevalence of hypodontia in Koreans
Authors: Chung CJ , Han J‐H , Kim K‐H
Published: February 2008

Objective:  The objective of this study was to evaluate the pattern and prevalence of hypodontia in the Korean population along with its association with the dental and skeletal polymorphisms.

Subjects and materials:  The diagnostic materials including casts, panoramic radiographs, and lateral cephalograms of 1622 Korean subjects (611 males, 1011 females) were used to evaluate the pattern and prevalence of hypodontia as well as its association with the congenital absence of the third molar. The changes in the tooth size and skeletal characteristics of the hypodontia group were evaluated using cast/cephalometric analysis and compared with the standard values of normal occlusion in Koreans.

Results:  The prevalence of hypodontia in Koreans was 11.2%. The mandibular lateral incisor and second premolar were the most frequently absent. Congenital absence of the third molar was observed more frequently in the hypodontia group than in the non‐hypodontia group. The prevalence of hypodontia in Class III malocclusion was significantly higher than in Class I or Class II malocclusion.

Conclusion:  The pattern and prevalence of hypodontia can vary in different ethnic groups. In Koreans, the special features of hypodontia were its association with a higher level of congenital missing third molars and skeletal Class III malocclusion.
ANTIBACTERIAL ACTIVITY AND BINDING ABILITY OF BOVINE LACTOFERRIN AGAINST PSEUDOMONAS SPP.
Authors: KIM WOAN‐SUB , RAHMAN M.M. , SHIMAZAKI KEI‐ICHI
Published: February 2008

The antibacterial activity of bovine lactoferrin was tested against Pseudomonas fluorescens and Pseudomonas syringae. The activity was studied by monitoring the growth of a Pseudomonas spp. in the presence or absence of bovine apo‐lactoferrin, bovine holo‐lactoferrin or native‐lactoferrin in liquid media at different concentrations. Lactoferrin‐binding proteins in the membrane fractions of Pseudomonas spp. were detected using far‐Western blot analysis. The addition of bovine lactoferrin to the medium inhibited the growth of all tested strains. Furthermore, the growth of P. fluorescens and P. syringae was strongly inhibited by bovine apo‐lactoferrin. The estimated molecular weights of lactoferrin‐binding proteins in P. fluorescens were 70, 49, 47 and 25 kDa, and 70, 48 and 28 kDa in P. syringae.

PRACTICAL APPLICATIONS

Pseudomonas fluorescens is an important psychrotrophic bacterium responsible for undesirable flavors in milk and dairy products. Thus, flavor and texture defects, such as bitterness and running paste, were also reported. In addition, Pseudomonas syringae causes various diseases on many different susceptible plant species, generally producing chlorotic and necrotic lesions on leaves and fruits. The resultant bacterial spoilage causes considerable economic losses for the food and dairy industries. At present, antiseptics and agricultural chemicals are used for defense of foods and vegetables from these bacteria, but such substances are known to deleteriously affect the human body. The results of this study demonstrate that bovine lactoferrin significantly inhibits the growth of P. fluorescens and P. syringae. The results indicate that the incorporation of bovine lactoferrin is expected to protect dairy products, food and fruits from pathogenic bacteria.
EFFECT OF LACTOBACILLUS SAKEI AND STAPHYLOCOCCUS XYLOSUS ON THE INHIBITION OF ESCHERICHIA COLI O157:H7 IN PASTIRMA, A DRY‐CURED MEAT PRODUCT
Authors: AKSU MUHAMMET İRFAN , KAYA MÜKERREM , OZ FATIH
Published: February 2008

Pastırma was produced from beef meat contaminated with Escherichia coli O157:H7 to investigate the effects of protective cultures on the behavior of E. coli O157:H7 in pastırma manufacturing. After being contaminated with E. coli O157:H7 (105 cfu/g), meats for pastırma were divided into two groups. The control group was untreated meat, and the treatment group was meat in which protective cultures (Lactobacillus sakei + Staphylococcus xylosus) were added. E. coli O157:H7 was decreased during processing and showed approximately a 3 log cycle reduction at the end of the production. At the end of the second drying step, there was a difference in E. coli O157:H7 levels between the cultured and control groups. There was no such difference after the other manufacturing steps. As a result, it was concluded that the most important factor effecting reduction of E. coli O157:H7 in pastırma production was loss of water in the drying process.

PRACTICAL APPLICATIONS

Escherichia coli O157:H7 is the most dangerous food pathogen in pastırma and similar dry‐cured meat products if it contaminates the carcass and muscles from the slaughterhouse. It has been found that the use of protective culture and the procedure of pastırma are effective for inhibiting E. coli O157:H7 during pastırma manufacturing. Results of this study can be applied to inhibit E. coli O157:H7 in pastırma.
ASSESSMENT OF THE MICROBIOLOGICAL CHARACTERISTICS OF INDUSTRIALLY PRODUCED ALHEIRA, WITH PARTICULAR REFERENCE TO FOODBORNE PATHOGENS
Authors: ESTEVES ALEXANDRA , PATARATA LUIS , SARAIVA CRISTINA , MARTINS CONCEIÇÃO
Published: February 2008

Alheiras is a traditional Portuguese meat product, typically from the north of the country. To investigate on some of the microbiological and physicochemical characteristics of industrially produced alheira, samples from four factories and six production batches were analyzed. The microbiological status of the analyzed samples can be considered a matter of concern in terms of food safety. Considering the microbiological counts and the pathogen occurrence rate, it can be inferred that most of the alheira samples were produced under substandard hygienic conditions. Staphylococcus aureus, Clostridium perfringens and Salmonella spp. were prevalent in 50, 25 and 12.5% of the samples, respectively. Listeria monocytogenes, Bacillus cereus and Yersinia enterocolitica were present in smaller numbers. Escherichia coli O157:H7 and enteropathogenic Campylobacter were not detected. The source factory was a determining factor in terms of microbiological characteristics and pathogen occurrence levels.

PRACTICAL APPLICATIONS

Given the significant economic importance of alheira (a traditional Portuguese sausage) to a number of small domestic and industrial producers, particularly in the north of Portugal, this study can be used to help implement strategies designed to enhance the product's microbiological quality. This would therefore have positive knock‐on effects on the region's economy and community as a whole.

The next logical step would be to carry out a systematic analysis of contamination patterns along alheira production lines, which should enable the introduction of more specific and effective methods of ensuring product safety in the face of common microbiological hazards. There also appears to be an urgent need for the establishment of a thorough technical and scientific monitoring program across the industry. This would include testing the technological procedures involved in the production process, and would clearly lead to a significant improvement in this product's microbiological profile.
INFLUENCE OF STORAGE TEMPERATURE ON COOLING INTENSITY OF TOPICAL EMULSIONS CONTAINING ENCAPSULATED MENTHOL
Authors: ZAGUE VIVIAN , DE OLIVEIRA NISHIKAWA DEBORAH , DE ALMEIDA SILVA DIEGO , BABY ANDRÉ ROLIM , BEHRENS JORGE HERMAN , KANEKO TELMA MARY , VELASCO MARIA VALÉRIA ROBLES
Published: February 2008

The cooling intensity of topical emulsions added with encapsulated or free menthol was evaluated by a screened and trained panel recruited based on the American Society for Testing and Materials method. A sensory panel composed of 10 trained judges performed the evaluation of samples stored at 22 ± 2C for 24 h and, after 28 days of storage, at 37.0 ± 0.5C. The obtained data were analyzed by analysis of variance and Tukey's test. The results showed an increase of cooling intensity as a function of encapsulated menthol concentration. The opposite was observed in samples added with free menthol, which may have caused sensory fatigue. Storage at 37 ± 0.5C for 28 days had no impact on the cooling intensity of emulsions containing encapsulated menthol, demonstrating high stability and suggesting its application in cooling skin care products. In contrast, emulsions added with free menthol showed a drastic decrease of cooling intensity at 37 ± 0.5C.

PRATICAL APPLICATIONS

This article deals with sensory assessment of the cooling intensity of topical emulsions added with encapsulated menthol under accelerated storage conditions. In all, the work is a major contribution to (1) investigating the feasibility of sensory analysis for evaluating the sensory properties of topical products during storage; (2) verifying the cooling intensity of topical emulsions containing encapsulated menthol; and (3) evaluating the effect of encapsulation of menthol on its stability during accelerated storage conditions.
FLAVOR DIFFERENCES IN HETEROGENEOUS FOODS CAN BE DETECTED USING REPEATED MEASURES OF CONSUMER PREFERENCES
Authors: HARKER F. ROGER , AMOS RACHEL L. , WHITE ANNE , PETLEY MARY B. , WOHLERS MARK
Published: February 2008

A method in which repeated hedonic measurements are used to infer flavor differences was proposed and tested using kiwifruit. Consumers assessed kiwifruit that had been treated with 1‐methylcyclopropane (1‐MCP, SmartFresh, AgroFresh Inc., Philadelphia, PA), a product used to manage the rate of ripening of fruits. Each consumer tasted four pairs of kiwifruit represented by a 2 × 2 design (high and low sugar content by soft and firm texture), and each pair of fruit included a 1‐MCP‐treated and control kiwifruit. Significant differences in consumer liking were found for kiwifruit with higher sugar content and firmer textures (two factors that were included as positive controls for panel sensitivity). However, no significant differences in liking were found between 1‐MCP and control kiwifruit. The repeated measures of preference for pairs of kiwifruit were subjected to analysis of probability, which confirmed that preferences for and against 1‐MCP were no different from the simple probability of tossing a coin four times. It was concluded that 1‐MCP did not affect the flavor of kiwifruit, and any preference expressed by consumers for or against 1‐MCP‐treated kiwifruit was due to other factors associated with biological variability in fruit quality.

PRACTICAL APPLICATIONS

This consumer method is presented for consideration and further evaluation. It is recommended as a useful addition to those currently available for assessing heterogeneous foods. In addition to providing information on liking scores and consumer preferences, it allows inferences to be made about the existence of qualitative differences in flavor.
QUESTIONNAIRE PRACTICE: WHAT HAPPENS WHEN THE JAR SCALE IS PLACED BETWEEN TWO “OVERALL” ACCEPTANCE SCALES?
Authors: GACULA MAXIMO , MOHAN PURNIMA , FALLER JIN , POLLACK LANA , MOSKOWITZ HOWARD R.
Published: February 2008

Using the observational analysis of two different foods as test products, this note examined some interesting findings that emerge when the just‐about‐right (JAR) scale was placed after the overall liking rating, and before the preference ranking. The JAR data appeared to be statistically uncorrelated with the overall rating scales. First, this fortuitous observation from several studies suggests that the JAR scale can play a diagnostic role to determine how the consumer feels about changing the product. Second, the statistical analysis of the JAR ratings (e.g., bipolar nature of the JAR scale, its skewness and kurtosis) all suggest that the appropriate measure is %JAR, an incidence metric, rather than scale average, ought to be used both to report the results, and to create models relating to the JAR versus sensory magnitude or versus liking, respectively.

PRACTICAL APPLICATIONS

The results of the present analysis suggest that overall acceptance/liking can be the last question in the questionnaire design. That location is very important for the sensory analysis of foods eaten over time and then rated, as well as personal care and cosmetic studies where the products are used over time periods, and where the true evaluation of performance ought to be made at the end of the trial. In these long‐term uses, overall liking is generally the last question given at the end of the time period of product evaluation. The facts that the just‐about‐right (JAR) scales are independent of this final overall liking rating suggest that the integrity of the overall evaluation and usefulness of JAR as diagnostics will not be compromised.
THE EFFECT OF RESISTANT STARCH ADDITION ON VISCOELASTIC PROPERTIES OF COOKED SPAGHETTI
Authors: SOZER NESLI , KAYA AHMET , DALGIC ALI COSKUN
Published: February 2008

Resistant starch is a good alternative to traditional fiber sources. From this point of view, it was used to enrich spaghetti, which is included in most diets. The effect of resistant starch addition on viscoelastic properties of spaghetti was investigated by stress–relaxation and creep tests. Tests were carried out with a TA‐XT2i texture analyzer. Relaxation and creep data were modeled by Maxwell, Peleg and Normand, Burgers, and Peleg. The three‐term Maxwell model and Burgers model were found to fit best to the relaxation and creep data, respectively. All samples started to lose their elastic behavior as cooking time proceeded. The parameters from the modeling of both stress relaxation and creep data showed that the addition of resistant starch resulted in spaghetti samples with similar viscoelastic values. However, data were different from those of the control.

PRACTICAL APPLICATIONS

The increased consumption of spaghetti with added resistant starch is proposed for health reasons. Resistant starch is believed to be a good alternative for traditional fiber sources like bran. The research reported in this article is part of a study conducted on the rheological properties of spaghetti enriched with resistant starch. The aim was to introduce a new healthy food product, based on spaghetti enriched with resistant starch, with improved mouthfeel and texture. Durum pasta cooking quality is highly influenced by starch and gluten. Gluten contributes to the physical properties, such as viscoelasticity, of pasta. Viscoelasticity is one of the most important rheological parameters determining spaghetti quality, especially in formulations where starch is more dominant. To the best of our knowledge, the effect of resistant starch addition on the viscoelasticity of cooked spaghetti has not been studied before. We believe that with this article, this concept can be better understood especially for pasta products.
RHEOLOGICAL AND SOME PHYSICOCHEMICAL CHARACTERISTICS OF SELECTED TURKISH HONEYS
Authors: KAYACIER AHMED , KARAMAN SAFA
Published: February 2008

In this study, some physicochemical properties and rheological characteristics of four Turkish honey samples were determined. Moisture content, ash content, pH and water activity of the samples were determined using standard procedures. The rheological properties of honeys were investigated using a controlled stress rheometer equipped with a plate–plate configuration over a temperature range of 10–40C. There was no difference among the honey varieties in terms of water activity values. Rheological results indicated that all samples exhibited Newtonian flow behavior. The viscosity varied between 2.8 and 101 Pa·s according to honey type and temperature. Temperature dependence of viscosity was adequately described by the Arrhenius relationship, with determination coefficients of 0.990 or greater. The calculated activation energy of the honey samples ranged from 63.4 to 78.5 kJ/mol. Viscosity of citrus honey, with the lowest activation energy, was found to be less sensitive to temperature change compared with other honey varieties.

PRACTICAL APPLICATIONS

Rheological properties of honey are very important in terms of applications related to handling, processing storage and quality control. Although Turkey is one of the leading honey producers in the world, information on the rheological characteristics of Turkish honey is lacking in the literature. In addition, temperature is a very important parameter affecting the viscosity of honey. The current study presents the viscosity characteristics of selected Turkish honeys, as well as the temperature dependence of viscosity using the Arrhenius model. Turkish honeys exhibited Newtonian flow, and the Arrhenius model successfully described the temperature–viscosity relationship.
CABINET DETERMINANTS OF STRUCTURAL REFORMS IN LATIN AMERICA, 1985–2000
Authors: ALTMAN David , CASTIGLIONI Rossana
Published: February 2008

Little research has been devoted to the analysis of how different characteristics of the executives affect structural reforms. This article analyzes the impact of cabinet fragmentation and the presidential ideological position on the scope of structural reforms in nine Latin American presidential democracies of the postauthoritarian period. In so doing, it treats cabinets as conglomerates of actors that are accountable both to the president and to their parties, with nonpartisan ministers being only accountable to the president. It shows that the higher the percentage of nonpartisan ministers, the lesser the costs associated with bargaining a reform within the executive. When presidents build governing coalitions, they limit their capacity of acting unilaterally. However, they are better able to advance their structural reform proposals than single‐party governments are. Data on cabinet composition were collected by the authors and data on the dependent variable structural reform comes from Lora (2001).
SHORT‐RUN AND LONG‐RUN DETERMINANTS OF THE REAL EXCHANGE RATE IN MEXICO
Authors: LÓPEZ VILLAVICENCIO Antonia , RAYMOND BARA Josep Lluís
Published: February 2008

This paper explores the real exchange rate behavior in Mexico from 1960 until 2005. Since the empirical analysis reveals that the real exchange rate is not mean reverting, we propose that economic fundamental variables affect its evolution in the long run. Therefore, based on equilibrium exchange rate paradigms, we propose a simple model of real exchange rate determination, which includes the relative GDP per capita, the real interest rates, and the net foreign assets over a long period of time. Our analysis also considers the dynamic adjustment in response to shocks through impulse response functions derived from the multivariate vector autoregressive (VAR) model.
CAN A RULE‐BASED MONETARY POLICY FRAMEWORK WORK IN A DEVELOPING COUNTRY? THE CASE OF YEMEN
Authors: CHAMI Saade , ELEKDAG Selim , SCHNEIDER Todd , BEN LTAIFA Nabil
Published: February 2008

Monetary policy in Yemen is largely rudimentary and ad hoc in nature. The Central Bank of Yemen's (CBY) approach has been based on discretionary targeting of broad money without any clear target to anchor inflation expectations. This paper argues in favor of a new formal monetary policy framework for Yemen emphasizing a proactive and rule‐based approach with a greater direct focus on price stability in the context of a flexible management of the exchange rate. Although, as in many developing countries, institutional capacity is a concern, adopting a more formal framework could impel the kind of changes that are required to strengthen the ability of the CBY in achieving low and stable rates of inflation over the medium term.
An Ab Initio Study of At2 Antagonists
Authors: Jain Swati , Yadav Arpita
Published: February 2008

In this study we report ab initio molecular orbital calculations on the natural hormone angiotensin II, which induces activity at AT1/AT2 receptor subtypes leading to vasoconstriction and subsequent hypertension, and AT2 antagonists. Pharmacophoric features of AT2 antagonists have been studied. A model of AT2 receptor has been made, and angiotensin II as well as antagonists has been systematically docked and their interactions with the receptor analyzed. Calculated ligand–receptor interaction energies have been correlated with experimentally observed biological potency data. Our studies indicate that antagonists retain sufficient interactions to block the receptor but may not be adequate to induce activity at the receptor. A poor antagonist is, therefore, proposed as a close mimic of angiotensin II in terms of interacting with the receptor. These studies further explore the mechanistic aspects of this important class of drugs.
Democracy, Minority Rights and Plural Societies:Plus ça Change?
Authors: Preece Jennifer Jackson
Published: February 2008

For more than a century, it was assumed that plural societies were unconducive to democratic government and assimilation a necessity. The end of the Cold War reopened the question of self‐determination and the concomitant issue of minority rights not only in Europe but also worldwide. As a result, minority rights and multiculturalism are emerging as the consensus position on democracy in plural societies. But it would be inaccurate and potentially unwise to regard this pluralist perspective as a universal remedy for the problems of diversity. Instead, the history of academic debate and public policy in this area as surveyed here is testimony to the fact that there can be no categorical imperatives when addressing problems of democratic governance in plural societies; both academics and policy‐makers would do well to remember that crucial fact.
Public Spaces of Dissent
Authors: Roberts John Michael
Published: February 2008

This article looks at some recent developments in the relationship between public space and dissent. The article does this by firstly distinguishing between dissent and resistance. Dissent is based broadly around disagreements between individuals in particular groups and contexts against a perceived grievance of some sort. As a result dissent can arise in a variety of contexts, especially within everyday life, popular culture, and with small acts of defiance against frustrations one experiences. These acts can also assume more overtly political modes in the form of resistance as when people demonstrate in the streets. The distinction is therefore useful because it helps us understand how the state and other governance mechanisms adopt policies and strategies to pre‐empt dissent and thereby prevent dissent from spilling over into resistance located in particular places. The article will examine how the state and governance have changed the way in which they pre‐empt the formation of spaces of dissent in order to effectively regulate them in the pre‐ and post‐9/11 climate. Taking examples from the USA and the UK, the paper explores these points through global social movements, law and dissent, planning and designing dissent, and the surveillance of dissent.
Family Leisure and Changing Ideologies of Parenthood
Authors: Shaw Susan M.
Published: February 2008

This paper examines the significant role that family leisure plays in family life, and the ways in which family time, family activities, and family vacations reflect and contribute to changing ideologies of parenthood (including ideologies of motherhood and fatherhood). Research on this topic has shown family leisure to be a parental commitment, organized and constructed for the benefit of children and for the family as a whole. At the same time, family leisure has contradictory meanings and outcomes, because of the work involved and the difficulties associated with organizing and facilitating positive family experiences. Moreover, the work of family leisure falls disproportionately to mothers, reducing their personal time and personal leisure. It is argued that family leisure is a new obligation of parenthood, and one that has important implications for understanding ideas, beliefs and practices associated with intensive motherhood and involved fatherhood.
Perceptions of and Responses to Stigma
Authors: LeBel Thomas P.
Published: February 2008

In the last 10 years, interest in the concept of stigma has grown remarkably throughout the social sciences. Today, stigma is an important topic that bridges many disciplines, including sociology, psychology, social psychology, and public health. This literature review primarily addresses perceptions of and responses to stigma from the insider's or target's perspective. The topics examined in this review include the following: defining stigma, public opinion and attitudes toward the stigmatized, measurement of perceptions of stigma and discrimination, the coping strategies employed by stigmatized persons to deal with stigma, the impact of stigma in terms of psychological and behavioral outcomes, explanations of coping strategies and outcomes, and strategies and interventions to reduce stigma. As many of the concerns faced by stigmatized persons are universal, what has been learned in research about one stigmatized group can provide insight into another. Promising directions for future stigma‐related research are identified and discussed.
Rosiglitazone increases fatty acid oxidation and fatty acid translocase (FAT/CD36) but not carnitine palmitoyltransferase I in rat muscle mitochondria
Authors: Benton Carley R. , Holloway Graham P. , Campbell S. E. , Yoshida Yuko , Tandon Narendra N. , Glatz Jan F. C. , Luiken Joost J. J. F. P. , Spriet Lawrence L. , Bonen Arend
Published: February 2008

Peroxisome proliferator‐activated receptors (PPARs) alter the expression of genes involved in regulating lipid metabolism. Rosiglitazone, a PPARγ agonist, induces tissue‐specific effects on lipid metabolism; however, its mode of action in skeletal muscle remains unclear. Since fatty acid translocase (FAT/CD36) was recently identified as a possible regulator of skeletal muscle fatty acid transport and mitochondrial fatty acid oxidation, we examined in this tissue the effects of rosiglitazone infusion (7 days, 1 mg day−1) on FAT/CD36 mRNA and protein, its plasmalemmal content and fatty acid transport. In addition, in isolated subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria we examined rates of fatty acid oxidation, FAT/CD36 and carnitine palmitoyltransferase I (CPTI) protein, and CPTI and β‐hydroxyacyl CoA dehydrogenase (β‐HAD) activities. Rosiglitazone did not alter FAT/CD36 mRNA or protein expression, FAT/CD36 plasmalemmal content, or the rate of fatty acid transport into muscle (P > 0.05). In contrast, rosiglitazone increased the rates of fatty acid oxidation in both SS (+21%) and IMF mitochondria (+36%). This was accompanied by concomitant increases in FAT/CD36 in subsarcolemmal (SS) (+43%) and intermyofibrillar (IMF) mitochondria (+46%), while SS and IMF CPTI protein content, and CPTI submaximal and maximal activities (P > 0.05) were not altered. Similarly, citrate synthase (CS) and β‐HAD activities were also not altered by rosiglitazone in SS and IMF mitochondria (P > 0.05). These studies provide another example whereby changes in mitochondrial fatty oxidation are associated with concomitant changes in mitochondrial FAT/CD36 independent of any changes in CPTI. Moreover, these studies identify for the first time a mechanism by which rosiglitazone stimulates fatty acid oxidation in skeletal muscle, namely the chronic, subcellular relocation of FAT/CD36 to mitochondria.
Contraction coupling efficiency of human first dorsal interosseous muscle
Authors: Jubrias Sharon A. , Vollestad Nina K. , Gronka Rod K. , Kushmerick Martin J.
Published: February 2008

During working contractions, chemical energy in the form of ATP is converted to external work. The efficiency of this conversion, called ‘contraction coupling efficiency’, is calculated by the ratio of work output to energy input from ATP splitting. Experiments on isolated muscles and permeabilized fibres show the efficiency of this conversion has a wide range, 0.2–0.7. We measured the work output in contractions of a single human hand muscle in vivo and of the ATP cost of that work to calculate the contraction coupling efficiency of the muscle. Five subjects performed six bouts of rapid voluntary contractions every 1.5 s for 42 s (28 contractions, each with time to peak force < 150 ms). The bouts encompassed a 7‐fold range of workloads. The ATP cost during work was quantified by measuring the extent of chemical changes within the muscle from 31P magnetic resonance spectra. Contraction coupling efficiency was determined as the slope of paired measurements of work output and ATP cost at the five graded work loads. The results show that 0.68 of the chemical energy available from ATP splitting was converted to external work output. A plausible mechanism to account for this high value is a substantially lower efficiency for mitochondrial ATP synthesis. The method described here can be used to analyse changes in the overall efficiency determined from oxygen consumption during exercise that can occur in disease or with age, and to test the hypothesis that such changes are due to reduced contraction coupling efficiency.
Propriospinal neurons are sufficient for bulbospinal transmission of the locomotor command signal in the neonatal rat spinal cord
Authors: Cowley Kristine C. , Zaporozhets Eugene , Schmidt Brian J.
Published: February 2008

We recently showed that propriospinal neurons contribute to bulbospinal activation of locomotor networks in the in vitro neonatal rat brainstem–spinal cord preparation. In the present study, we examined whether propriospinal neurons alone, in the absence of long direct bulbospinal transmission to the lumbar cord, can successfully mediate brainstem activation of the locomotor network. In the presence of staggered bilateral spinal cord hemisections, the brainstem was stimulated electrically while recording from lumbar ventral roots. The rostral hemisection was located between C1 and T3 and the contralateral caudal hemisection was located between T5 and mid‐L1. Locomotor‐like activity was evoked in 27% of the preparations, which included experiments with staggered hemisections placed only two segments apart. There was no relation between the likelihood of developing locomotor‐like activity and the distance separating the two hemisections or specific level of the hemisections. In some experiments, where brainstem stimulation alone was ineffective, neurochemical excitation of propriospinal neurons (using 5‐HT and NMDA) at concentrations subthreshold for producing locomotor‐like activity, promoted locomotor‐like activity in conjunction with brainstem stimulation. In other experiments, involving neither brainstem stimulation nor cord hemisections, the excitability of propriospinal neurons in the cervical and/or thoracic region was selectively enhanced by bath application of 5‐HT and NMDA or elevation of bath K+ concentration. These manipulations produced locomotor‐like activity in the lumbar region. In total, the results suggest that propriospinal neurons are sufficient for transmission of descending locomotor command signals. This observation has implications for regeneration strategies aimed at restoration of locomotor function after spinal cord injury.
Impaired GABAergic inhibition in the visual cortex of brain‐derived neurotrophic factor heterozygous knockout mice
Authors: Abidin Ismail , Eysel Ulf T. , Lessmann Volkmar , Mittmann Thomas
Published: February 2008

Brain derived neurotrophic factor (BDNF) promotes the formation, maturation and stabilization of inhibitory synapses in the central nervous system. In addition, BDNF has been suggested to regulate the critical period for ocular dominance plasticity in the visual system. Here we further evaluated the role of BDNF in the visual cortex by studying the GABAergic synaptic transmission under conditions of chronically reduced levels of BDNF. Whole‐cell patch‐clamp recordings were performed from pyramidal neurons located in layers II/III of visual cortical slices in heterozygous BDNF knockout mice (BDNF (+/−)) and their wild‐type littermates at the age of 21–25 days. The BDNF (+/−) mice showed a decreased frequency and amplitude of miniature inhibitory postsynaptic currents (mIPSCs) as well as a reduced amplitude and prolonged decay time constant of evoked IPSCs. Further analyses indicated an impaired presynaptic GABAergic function in BDNF (+/−) mice, as shown by the decreased release probability, steady‐state release and synchronous release of GABA. However, the number of functional release sites remained unchanged. In line with these observations, an impaired glutamate‐driven GABA release was observed in BDNF (+/−) mice. Furthermore, the overall balance in the strength of cortical excitation to inhibition shifted towards a decreased inhibition. Finally, the reversal potential for chloride‐mediated evoked IPSCs was not affected. These findings suggested that chronically reduced levels of BDNF strongly impair the GABAergic inhibitory function in visual cortex by altering postsynaptic properties and by reducing presynaptic GABA release as well as the overall strength of inhibition onto pyramidal neurons within the cortical network. These impairments of inhibitory function are compatible with a rather immature status of the GABAergic system in BDNF (+/−) mice, which supports the hypothesis that the level of expression for BDNF critically affects maturation and function of the GABAergic inhibition.
Movement‐related receptive fields of spinal motoneurones with active dendrites
Authors: Hyngstrom Allison , Johnson Michael , Schuster Jenna , Heckman C. J.
Published: February 2008

The primary control of spinal motoneurone excitability is mediated by descending monoaminergic systems, which have diffuse effects on multiple motor pools. Much of the sensory input evoked by movement is also distributed broadly to multiple joints. The muscle spindle Ia afferent system, however, is sharply focused, with Ia excitation restricted to close synergists and Ia reciprocal inhibition only shared between antagonists acting at a single joint. We studied the interaction of neuromodulatory and sensory inputs in determining the movement‐related receptive field (MRRF) of motoneurones during passive joint movements of the cat hindlimb. In a decerebrate preparation with tonic monoaminergic input to the cord, the MRRFs tended to be focused for the ankle and knee extensor motor pools studied. Ankle rotation produced larger synaptic currents in ankle extensors than knee or hip rotations and knee rotation dominated input to the knee extensors. The persistent inward current (PIC) in motoneurone dendrites, which is facilitated by monoaminergic input, amplified the MRRF about 2‐fold, consistent with its effects on other inputs. Acute spinal transaction markedly broadened MRRFs, with hip rotation generating large currents in both ankle and knee extensors. Spinalization also eliminated amplification of MRRFs, as expected from elimination of descending monoaminergic input. Ia reciprocal inhibition is very effective in suppressing dendritic PICs and thus provides a local and specific PIC control system to oppose the diffuse PIC facilitation from descending monoaminergic systems. The focused MRRF seen in the intact cord state would allow reciprocal inhibition to fulfil this role without undue interference from multijoint input from other afferent systems.
Unsteady behavior of flow in a scaled-up vocal folds model
Authors: Krane Michael , Barry Michael , Wei Timothy
Published: February 2008

Measurements of the fluid flow through a scaled-up model of the human glottis are presented to determine whether glottal flow may be approximated as unsteady. Time- and space-resolved velocity vector fields from digital particle image velocimetry (DPIV) measurements of the flow through the gap between two moving, rigid walls are presented in four cases, over a range of Strouhal numbers: 0.010, 0.018, 0.035, 0.040, corresponding to life-scale f0 of 30, 58, 109, and 126Hz, respectively, at a Reynolds number of 8000. It is observed that (1) glottal flow onset is delayed after glottal opening and (2) glottal flow shutoff occurs prior to closure. A comparison between flow through a fully open, nonmoving glottis and that through the moving vocal folds shows a marked difference in spatial structure of the glottal jet. The following features of the flow are seen to exhibit strong dependence on cycle frequency: (a) glottal exit plane velocity, (b) volume flow, (c) vortex shedding rates, and (d) vortex amplitude. Vortex shedding appears to be a factor both in controlling flow resistance and in cycle-to-cycle volume flow variations. All these observations strongly suggest that glottal flow is inherently unsteady.
Spatial structure of low-frequency wind noise
Authors: Wilson D. Keith , Greenfield Roy J. , White Michael J.
Published: February 2008

The distinguishing spatial properties of low-frequency microphone wind noise (turbulent pressure disturbances) are examined with a planar, 49-element array. Individual, propagating transient pressure disturbances are imaged by wavelet processing to the array data. Within a given frequency range, the wind disturbances are much smaller and less spatially coherent than sound waves. Conventional array processing techniques are particularly sensitive to wind noise when sensor separations are small compared to the acoustic wavelengths of interest.
Acoustoelasticity in soft solids: Assessment of the nonlinear shear modulus with the acoustic radiation force
Authors: Gennisson J.-L. , Rénier M. , Catheline S. , Barrière C. , Bercoff J. , Tanter M. , Fink M.
Published: February 2008

The assessment of viscoelastic properties of soft tissues is enjoying a growing interest in the field of medical imaging as pathologies are often correlated with a local change of stiffness. To date, advanced techniques in that field have been concentrating on the estimation of the second order elastic modulus (μ). In this paper, the nonlinear behavior of quasi-incompressible soft solids is investigated using the supersonic shear imaging technique based on the remote generation of polarized plane shear waves in tissues induced by the acoustic radiation force. Applying a theoretical approach of the strain energy in soft solid [Hamilton et al., J. Acoust. Soc. Am. 116, 41–44 (2004)], it is shown that the well-known acoustoelasticity experiment allowing the recovery of higher order elastic moduli can be greatly simplified. Experimentally, it requires measurements of the local speed of polarized plane shear waves in a statically and uniaxially stressed isotropic medium. These shear wave speed estimates are obtained by imaging the shear wave propagation in soft media with an ultrafast echographic scanner. In this situation, the uniaxial static stress induces anisotropy due to the nonlinear effects and results in a change of shear wave speed. Then the third order elastic modulus (A) is measured in agar-gelatin-based phantoms and polyvinyl alcohol based phantoms.
The effect of hair on auditory localization cues
Authors: Treeby Bradley E. , Pan Jie , Paurobally Roshun M.
Published: February 2008

Previous empirical and analytical investigations into human sound localization have illustrated that the head-related transfer function (HRTF) and interaural cues are affected by the acoustic material properties of the head. This study utilizes a recent analytical treatment of the sphere scattering problem (which accounts for a hemispherically divided surface boundary) to investigate the contribution of hair to the auditory cues below 5kHz. The hair is modeled using a locally reactive equivalent impedance parameter, and cue changes are discussed for several cases of measured hair impedance. The hair is shown to produce asymmetric perturbations to the HRTF and the interaural time and level differences. The changes in the azimuth plane are explicated via analytical examination of the surface pressure variations with source angle. Experimental HRTFs obtained using a sphere with and without a hemispherical covering of synthetic hair show a good agreement with analytical results. Additional experimental and analytical investigations illustrate that the relative contribution of the hair remains robust, regardless of the placement of the pinnas, or inclusion of a cylindrical neck.
Within- and across-channel gap detection in cochlear implant listeners
Authors: Grose John H. , Buss Emily
Published: February 2008

This study examined within- and across-electrode-channel processing of temporal gaps in successful users of MED-EL COMBI 40+ cochlear implants. The first experiment tested across-ear gap duration discrimination (GDD) in four listeners with bilateral implants. The results demonstrated that across-ear GDD thresholds are elevated relative to monaural, within-electrode-channel thresholds; the size of the threshold shift was approximately the same as for monaural, across-electrode-channel configurations. Experiment 1 also demonstrated a decline in GDD performance for channel-asymmetric markers. The second experiment tested the effect of envelope fluctuation on gap detection (GD) for monaural markers carried on a single electrode channel. Results from five cochlear implant listeners indicated that envelopes associated with 50-Hz wide bands of noise resulted in poorer GD thresholds than envelopes associated with 300-Hz wide bands of noise. In both cases GD thresholds improved when envelope fluctuations were compressed by an exponent of 0.2. The results of both experiments parallel those found for acoustic hearing, therefore suggesting that temporal processing of gaps is largely limited by factors central to the cochlea.
Low frequency sound scattering from spherical assemblages of bubbles using effective medium theory
Authors: Hahn Thomas R.
Published: February 2008

The determination of the acoustic field scattered by an underwater assembly of gas bubbles or similar resonant monopole scatterers is of considerable theoretical and practical interest. This problem is addressed from a theoretical point of view within the framework of the effective medium theory for the case of spherically shaped assemblages. Although being valid more generally, the effective medium theory is an ideal instrument to study multiple scattering effects such as low frequency collective resonances, acoustically coupled breathing modes of the entire assembly. Explicit expressions for the scattering amplitude and cross sections are derived, as well as closed form expressions for the resonance frequency and spectral shape of the fundamental collective mode utilizing analytical S-matrix methods. This approach allows, in principle, a simultaneous inversion for the assembly radius and void fraction directly from the scattering cross sections. To demonstrate the validity of the approach, the theory is applied to the example of idealized, spherically shaped schools of swim bladder bearing fish. The analytic results of the theory are compared to numerical first-principle benchmark computations and excellent agreement is found, even for densely packed schools and frequencies across the bladder resonance.
Determining dominant scatterers of sound in mixed zooplankton populations
Authors: Lavery Andone C. , Wiebe Peter H. , Stanton Timothy K. , Lawson Gareth L. , Benfield Mark C. , Copley Nancy
Published: February 2008

High-frequency acoustic scattering techniques have been used to investigate dominant scatterers in mixed zooplankton populations. Volume backscattering was measured in the Gulf of Maine at 43, 120, 200, and 420kHz. Zooplankton composition and size were determined using net and video sampling techniques, and water properties were determined using conductivity, temperature, and depth sensors. Dominant scatterers have been identified using recently developed scattering models for zooplankton and microstructure. Microstructure generally did not contribute to the scattering. At certain locations, gas-bearing zooplankton, that account for a small fraction of the total abundance and biomass, dominated the scattering at all frequencies. At these locations, acoustically inferred size agreed well with size determined from the net samples. Significant differences between the acoustic, net, and video estimates of abundance for these zooplankton are most likely due to limitations of the net and video techniques. No other type of biological scatterer ever dominated the scattering at all frequencies. Copepods, fluid-like zooplankton that account for most of the abundance and biomass, dominated at select locations only at the highest frequencies. At these locations, acoustically inferred abundance agreed well with net and video estimates. A general approach for the difficult problem of interpreting high-frequency acoustic scattering in mixed zooplankton populations is described.
Near-specular acoustic scattering from a buried submarine mud volcano
Authors: Gerig Anthony L. , Holland Charles W.
Published: February 2008

Submarine mud volcanoes are objects that form on the seafloor due to the emission of gas and fluidized sediment from the Earth’s interior. They vary widely in size, can be exposed or buried, and are of interest to the underwater acoustics community as potential sources of active sonar clutter. Coincident seismic reflection data and low frequency bistatic scattering data were gathered from one such buried mud volcano located in the Straits of Sicily. The bistatic data were generated using a pulsed piston source and a 64-element horizontal array, both towed over the top of the volcano. The purpose of this work was to appropriately model low frequency scattering from the volcano using the bistatic returns, seismic bathymetry, and knowledge of the general geoacoustic properties of the area’s seabed to guide understanding and model development. Ray theory, with some approximations, was used to model acoustic propagation through overlying layers. Due to the volcano’s size, scattering was modeled using geometric acoustics and a simple representation of volcano shape. Modeled bistatic data compared relatively well with experimental data, although some features remain unexplained. Results of an inversion for the volcano’s reflection coefficient indicate that it may be acoustically softer than expected.