bluuebunny/crossref_metadata_2025 huggingface dataset:
Short‐term administration of the glucagon receptor antagonist LY2409021 lowers blood glucose in healthy people and in those with type 2 diabetes
Authors: Kelly R. P. , Garhyan P. , Raddad E. , Fu H. , Lim C. N. , Prince M. J. , Pinaire J. A. , Loh M. T. , Deeg M. A.
Published: February 2015

Aim

To describe the clinical effects of single and multiple doses of a potent, selective, orally administered, small‐molecule antagonist of the human glucagon receptor, LY2409021, in healthy subjects and in patients with type 2 diabetes.

Methods

LY2409021 was administered in dose‐escalation studies to healthy subjects (n = 23) and patients with type 2 diabetes (n = 9) as single doses (Study 1) and daily to patients with type 2 diabetes (n = 47) for 28 days (Study 2). Safety, tolerability, pharmacokinetic (PK) and pharmacodynamic (PD) assessments were made after single doses and in patients receiving once‐daily doses of LY2409021 (5, 30, 60 or 90 mg) for 28 days.

Results

LY2409021 was well tolerated at all dose levels in both studies. Fasting and postprandial glucose were reduced and glucagon levels increased after single and multiple dosing, with reductions in fasting serum glucose of up to ∼1.25 mmol/l on day 28. Serum aminotransferases increased in a dose‐dependent manner with multiple dosing and reversed after cessation of dosing. Significant glucose‐lowering was observed with LY2409021 at dose levels associated with only minor aminotransferase increases.

Conclusion

Blockade of glucagon signalling in patients with type 2 diabetes is well tolerated and results in substantial reduction of fasting and postprandial glucose with minimal hypoglycaemia, but with reversible increases in aminotransferases. Inhibition of glucagon signalling by LY2409021 is a promising potential treatment for patients with type 2 diabetes and should be evaluated in longer clinical trials to better evaluate benefits and risks.
A novel peripheral cannabinoid receptor 1 antagonist, BPR0912, reduces weight independently of food intake and modulates thermogenesis
Authors: Hsiao W.‐C. , Shia K.‐S. , Wang Y.‐T. , Yeh Y.‐N. , Chang C.‐P. , Lin Y. , Chen P.‐H. , Wu C.‐H. , Chao Y.‐S. , Hung M.‐S.
Published: February 2015

Aim

To investigate the in vivo metabolic effects of treatment with BPR0912, a novel and potent peripheral cannabinoid receptor 1 (CB1R) antagonist, on both normal mice and diet‐induced obese (DIO) mice.

Methods

The acute peripheral effects of BPR0912 administration on gastrointestinal transit and energy metabolism in normal mice were investigated. The effects of chronic BPR0912 treatment were compared with those of rimonabant using DIO mice. Alterations to body weight and biochemical and metabolic variables were determined.

Results

Acute treatment with BPR0912 did not alter food intake or energy metabolism, but efficiently reversed CB1R‐mediated gastrointestinal delay. Chronic treatment of DIO mice with BPR0912 showed that BPR0912 exerts a food intake‐independent mechanism, which contributes to weight loss. Genes involved in β‐oxidation and thermogenesis were upregulated in white adipose tissue (WAT) in addition to increased lipolytic activity, whereas Ucp1 expression was induced in brown adipose tissue (BAT) and body temperature was elevated. Expression of the β2‐adrenoceptor was specifically elevated in both WAT and BAT in a manner dependent on the BPR0912 dose. Lastly, chronic BPR0912 treatment was more efficacious than rimonabant in reducing hepatic triglycerides in DIO mice.

Conclusion

BPR0912 exhibits significant in vivo efficacy in inducing food intake‐independent weight loss in DIO mice, while tending to reduce their hepatic steatosis. The thermogenic effects of BPR0912, as well as its modulation of protein and gene expression patterns in WAT and BAT, may enhance its efficacy as an anti‐obesity agent. The results of the present study support the benefits of the use of peripheral CB1R antagonists to combat metabolic disorders.
Adverse Selection, Gresham's Law and State Regulation
Authors: Ricketts Martin
Published: February 2015

Regulation is often justified as a response to adverse selection caused by poorly informed buyers and as a means of preventing a ‘race to the bottom’ in competitive markets. This paper argues that competitive markets respond with a variety of institutional mechanisms to problems of adverse selection and that these are often subverted by regulation. Far from Gresham's Law being associated with competitive market processes, it is actually more correctly viewed as the outcome of regulatory intervention that weakens the quality‐protecting incentives that economic agents would otherwise face.
Avian mite dermatitis: an Italian case indicating the establishment and spread of Ornithonyssus bursa (Acari: Gamasida: Macronyssidae) (Berlese, 1888) in Europe
Authors: Castelli Elena , Viviano Enza , Torina Alessandra , Caputo Valentina , Bongiorno Maria Rita
Published: February 2015

Background

Avian mite dermatitis is a skin disease caused in mammals by the incidental bites of blood‐sucking mites which customarily parasitize wild and domestic birds. It manifests in the form of pruritic, erythematous, or urticarial papules, with a central sting mark, in skin regions normally covered by clothing. The species mainly implicated in human bite cases are Dermanyssus gallinae, Ornithonyssus sylviarum and, less frequently, Ornithonyssus bursa. The latter is mainly a tropical and subtropical mite and its – presumably transitory – presence has been recorded only once in Europe, in migratory birds.

Case report

We report a case of avian mite dermatitis in a 70‐year‐old man, an owner of chickens, who lived in Sicily, an island in southern Italy. He presented with an itching, erythematous, papular eruption. Numerous mites were seen racing across his skin. The precise identification of O. bursa was based on the morphology of its plates and chelicerae and on the arrangement of its setae.

Conclusions

Not only does this paper report the first European case of human infestation with O. bursa, it provides evidence that this alien species has settled and spread in the Old Continent. It may have been flown in from a small focus reported in Danish migratory birds in the 1980s or may have been accidentally introduced into Italy through the importation of infested poultry from South America. Such occurrences may have unpredictable epidemiological and ecological consequences. More comprehensive veterinary inspection of imported birds is desirable.
A Case of Atrial Tachycardia Treated with Ivabradine as Bridge to Ablation
Authors: MELES ESTER , CARBONE CLAUDIO , MAGGIOLINI STEFANO , MORETTI PAOLO , DE CARLINI CATERINA C. , GENTILE GAETANO , GNECCHI‐RUSCONE TOMASO
Published: February 2015

Ivabradine in Atrial Tachycardia

Ivabradine is indicated in cardiac failure and ischemia to reduce sinus rate by inhibition of the pacemaker I(f) current in sinoatrial node. We report a case of an 18‐year‐old woman with left atrial tachyarrhythmia resistant to several antiarrhythmic drugs and to electric cardioversion who responded only to ivabradine, which significantly reduced heart rate without abolishing the arrhythmia itself. An ectopic focus in the ostium of left pulmonary veins was found and the patient was successfully ablated. We suggest that ivabradine might be therefore useful in the treatment of supraventricular tachyarrhythmias due to an enhanced automaticity.
A Single Visit Direct Technique to Provisionally Restore Occlusion for a Full‐Mouth Rehabilitation: A Clinical Report
Authors: El‐Kerdani Tarek , Nimmo Arthur
Published: February 2015

Attrition of the dentition can negatively affect esthetics and function. When reconstructing patients with attrition who require restoration at increased occlusal vertical dimension (OVD), it is necessary to first evaluate the OVD using a removable interim prosthesis to ensure that the patient will tolerate the new position. The transition to fixed interim prostheses has to be carefully planned to achieve the desired OVD. One approach is to prepare all teeth in a single day and place full‐arch interim prostheses; however, this can be tiring for the patient and prosthodontist. An alternative approach is to prepare one arch and place interim prostheses, while using composite resin in the opposing arch to maintain the newly established OVD. A diagnostic wax‐up at the proposed OVD is completed and duplicated in stone. A vacuform matrix is loaded with composite resin and applied to the unprepared etched teeth of the opposing arch to restore form and occlusion until full contour interim prostheses are placed at a later visit.
Defence‐Related Enzymes in Soybean Resistance to Target Spot
Authors: Fortunato Alessandro A. , Debona Daniel , Bernardeli Arthur M. A. , Rodrigues Fabrício A.
Published: February 2015

Target spot, caused by the fungus Corynespora cassiicola, has become a serious foliar disease in soybean production in the Brazilian Cerrado. Information in the literature regarding the biochemical defence responses of soybean to C. cassiicola infection is rare. Therefore, the objective of this study was to determine the biochemical features associated with soybean resistance to target spot. The activities of chitinases (CHI), β‐1‐3‐glucanases (GLU), phenylalanine ammonia‐lyases (PAL), peroxidases (POX), polyphenol oxidases (PPO) and lipoxygenases (LOX), as well as the concentrations of total soluble phenolics (TSP) and lignin‐thioglycolic acid (LTGA) derivatives, were determined in soybean leaves from both a resistant (FUNDACEP 59) and a susceptible (TMG 132) cultivar. The target spot severity, number of lesions per cm2 of leaflet and area under the disease progress curve were significantly lower for plants from cv. FUNDACEP 59 compared to plants from cv. TMG 132. The GLU, CHI, PAL, POX and PPO activities and the concentration of LTGA derivatives increased significantly, whereas LOX activity decreased significantly on the leaves infected by C. cassiicola. Inoculated plants from cv. FUNDACEP 59 showed a higher PPO activity and concentrations of TSP and LTGA derivatives at 4 and 6 days after inoculation compared to plants from cv. TMG 132. In conclusion, the results of this study demonstrated that the defence‐related enzyme activities increased upon C. cassiicola infection, regardless of the basal level of resistance of the cultivar studied. The increases in PPO activity and concentrations of TSP and LTGA derivatives, but lower LOX activity, at early stages of C. cassiicola infection were highly associated with soybean resistance to target spot.
Species‐Specific PCR‐Based Assay for Identification and Detection of Phomopsis (Diaporthe) azadirachtae Causing Die‐Back Disease in Azadirachta indica
Authors: Vedashree Sobagaiah , Sateesh Mysore Krishnaiah , Chowdappa Pallem , Nirmalkumar Bangalore Jayaseelan
Published: February 2015

Die‐back disease caused by Phomopsis (Diaporthe) azadirachtae is the devastating disease of Azadirachta indica. Accurate identification of P. azadirachtae is always problematic due to morphological plasticity and delayed appearance of conidia. A species‐specific PCR‐based assay was developed for rapid and reliable identification of P. azadirachtae by designing a species‐specific primer‐targeting ITS region of P. azadirachtae isolates. The assay was validated with DNA isolated from different Phomopsis species and other fungal isolates. The PCR assay amplified 313‐bp product from all the isolates of P. azadirachtae and not from any other Phomopsis species or any genera indicating its specificity. The assay successfully detected the pathogen DNA in naturally and artificially infected neem seeds and twigs indicating its applicability in seed quarantine and seed health testing. The sensitivity of the assay was 100 fg when genomic DNA of all isolates was analysed. The PCR‐based assay was 92% effective in comparison with seed plating technique in detecting the pathogen. This is the first report on the development of species‐specific PCR assay for identification and detection of P. azadirachtae. Thus, PCR‐based assay developed is very specific, rapid, confirmatory and sensitive tool for detection of pathogen P. azadirachtae at early stages.
Applying the Lewis Model in Industrialized Countries: W. Arthur Lewis and the Dual Economy of Manchester in the 1950s
Authors: Mosley Paul , Ingham Barbara
Published: February 2015

We document, for the first time, the institution‐building activities of the development economist W. Arthur Lewis (1915–91) as founder of Community House and the South Hulme Evening Centre, two further education centres which sought to fight discrimination among the Afro‐Caribbean communities of Manchester in the 1950s. We depict the struggle by Afro‐Caribbeans to achieve a decent standard of living (and to escape from the ‘subsistence economy’ which provides the basis for Lewis' most famous model) as a game of snakes and ladders in which the two main potential ladders out of poverty are—as in many developing countries—first, the ability to generate non‐wage income through self‐employment and second, ‘vertical social capital’, i.e. membership of social networks of a kind which gave the employee the ability to fight back against discrimination. The most imaginative aspect of Lewis's design for his further education centres is his incorporation of activities which build vertical social capital alongside conventional vocational training. On the basis of both the qualitative evidence and an exploratory model of the Manchester dual economy, we argue that Lewis' social centres had a significant positive impact on Afro‐Caribbean income and poverty levels, and that they still provide inspiration for development practitioners.
Emotions as Psychological Reactions
Authors: Zamuner Edoardo
Published: February 2015

Sometimes we speak of behaviours and actions as reactions, just as we speak of physical conditions and mental states as reactions. But what do we mean when we say that emotions are reactions? I answer this question by developing an account of emotions as psychological reactions to presentations or representations of states of affairs. I show that this account may provide a novel conceptual framework for explaining aspects of the intentionality, phenomenology and behavioural manifestation of emotions. I conclude by showing that this account is compatible with the view that emotions can be assessed on grounds of justification and correctness.
Uncertainty Without All the Doubt
Authors: Norby Aaron
Published: February 2015

I investigate whether degreed beliefs are able to play the predictive, explanatory, and modeling roles that they are frequently taken to play. The investigation focuses on evidence—both from sources familiar in epistemology as well as recent work in behavioral economics and cognitive psychology—of variability in agents' apparent degrees of belief. Although such variability has been noticed before, there has been little philosophical discussion of its breadth or of the psychological mechanisms underlying it. Once these are appreciated, the inadequacy of degrees of belief becomes clear. I offer a theoretical alternative to degrees of belief, what I call thefilter theory.
Attitudes to a robot bathtub in Danish elder care: A hermeneutic interview study
Authors: Beedholm Kirsten , Frederiksen Kirsten , Frederiksen Anne‐Marie Skovsgaard , Lomborg Kirsten
Published: February 2015

In Western countries, assistive technology is implemented on a large scale in elder care settings. Only a few studies have attempted to explore the different attitudes to assistive technology among various groups of users. In this study, we investigated and explained the different attitudes among the involved leaders, nursing staff, and older people to a newly‐implemented robot bathtub. Qualitative analyses of eight interviews with managers, nursing staff, and the older users revealed that the informants focused on different aspects (process, values, and functionality, respectively), used different implicit quality criteria, and ascribed different symbolic significance to the robot bathtub. Thus, the study demonstrated how attitudes toward the robot bathtub were connected to the informants’ institutional role. The findings challenge the current paradigm, where technology is expected to operate as a passive tool, simply facilitating desired human acts and interactions. Further studies drawing on the epistemological and ontological perceptions of science technology studies are needed in order to understand human rationalities in the assistive technology context and to offer new insights into how technology “works” in organizations.
Keeping a cool head: gene networks underlying chilling‐induced male sterility in rice
Authors: NOCTOR GRAHAM
Published: February 2015

This article comments on: Cooling water before panicle initiation increases chilling‐induced male sterility and disables chilling‐induced expression of genes encoding OsFKBP65 and heat shock proteins in rice spikelets
Comparative transcriptome analysis of developmental stages of the Limonium bicolor leaf generates insights into salt gland differentiation
Authors: YUAN FANG , LYU MING‐JU AMY , LENG BING‐YING , ZHENG GUANG‐YONG , FENG ZHONG‐TAO , LI PING‐HUA , ZHU XIN‐GUANG , WANG BAO‐SHAN
Published: February 2015

With the expansion of saline land worldwide, it is essential to establish a model halophyte to study the salt‐tolerance mechanism. The salt glands in the epidermis of Limonium bicolor (a recretohalophyte) play a pivotal role in salt tolerance by secreting excess salts from tissues. Despite the importance of salt secretion, nothing is known about the molecular mechanisms of salt gland development. In this study, we applied RNA sequencing to profile early leaf development using five distinct developmental stages, which were quantified by successive collections of the first true leaves of L. bicolor with precise spatial and temporal resolution. Specific gene expression patterns were identified for each developmental stage. In particular, we found that genes controlling salt gland differentiation in L. bicolor may evolve in a trichome formation, which was also confirmed by mutants with increased salt gland densities. Genes involved in the special ultrastructure of salt glands were also elucidated. Twenty‐six genes were proposed to participate in salt gland differentiation. Our dataset sheds light on the molecular processes underpinning salt gland development and thus represents a first step towards the bioengineering of active salt‐secretion capacity in crops.
Die or survive? Redox changes as seed viability markers
Authors: KOCSY GÁBOR
Published: February 2015

This article comments on: Genome‐wide association mapping and biochemical markers reveal that seed ageing and longevity are intricately affected by genetic background and developmental and environmental conditions in barley
THE COMPETITIVENESS OF INDONESIAN WOOD‐BASED PRODUCTS
Authors: Oh Jinhwan , Siswadi  , Kim Jihee
Published: February 2015

This paper analyzes the competitiveness of Indonesian wood‐based products using revealed symmetric comparative advantage (RSCA), Spearman rank correlation (SRC), product mapping, and constant market share (CMS) analyses. RSCA results show that Indonesia had a comparative advantage in wood‐based products, especially in Standard International Trade Classification (SITC) 245, 248, 251, 634, 635, 641, and 821. SRC results find that Indonesian wood‐based products do not show a structural shift in comparative advantage during 1991–2010 while product mapping places Indonesia in group A (comparative advantage and a net exporter) in SITC 245, 634, and 635. CMS reveals that the increase in wood‐based product export was caused by an increase in world exports, and commodity and market distribution effects. This study examines Indonesia's log export ban policies, which have been inconsistently implemented for the past several decades and adversely affect the country's global competitiveness, and recommends that Jakarta eliminate these policies and impose an appropriate export tax rate on logs.
Social Categorization in Intergroup Contexts: Three Kinds of Self‐Categorization
Authors: Leonardelli Geoffrey J. , Toh Soo Min
Published: February 2015

In reviewing self‐categorization theory and the literature upon which it is based, we conclude that individuals' attempts to form social categories could lead to three kinds of self‐categorization. We label them intergroup categorization, ingroup categorization, and outgroup categorization. We review literature supporting these three types and argue that they can help to explain and organize the existing evidence. Moreover, we conclude that distinguishing these three kinds of self‐categorization lead to novel predictions regarding social identity, social cognition, and groups. We offer some of those predictions by discussing their potential causes (building from optimal distinctiveness and security seeking literatures) and implications (on topics including prototype complexity, self‐stereotyping, stereotype formation, intergroup behavior, dual identity, conformity, and the psychological implications of perceiving uncategorized collections of people). This paper offers a platform from which to build theoretical and empirical advances in social identity, social cognition, and intergroup relations.
A new preparation method for red blood cells for intrauterine transfusion enabling reduction of donor exposure
Authors: Bontekoe Ido J. , Scharenberg John , Schonewille Henk , Zwaginga Jaap Jan , Brand Anneke , van der Meer Pieter F. , de Korte Dirk
Published: February 2015

BACKGROUND

Severe hemolytic anemia of the fetus, caused by maternal red blood cell (RBC) alloantibodies, is treated with intrauterine transfusion (IUT) of RBCs. Because IUT is associated with additional antibody formation, RBCs with the closest match between donor and mother are preferred. Because one fetus needs a median of three IUTs, finding such RBCs is complicated. Collection of repeated low‐volume donations from one selected donor during the entire IUT treatment period would reduce donor exposure and possibly IUT‐associated alloimmunization.

STUDY DESIGN AND METHODS

Whole blood (WB) donations of 100 and 200 mL were diluted with saline, filtered, centrifuged, and separated to prepare experimental RBCs. Before and after gamma irradiation, the RBCs were sampled for comparison of in vitro quality with standard RBCs for IUT. An additional washing procedure was investigated to remove anti‐A/‐B.

RESULTS

Experimental RBCs were leukoreduced to levels conforming with current guidelines and had final volumes of 44 (n = 12) and 84 (n = 8) mL with hematocrit levels between 0.80 and 0.88 L/L. Hemolysis was lower (0.12% vs. 0.42%), potassium leakage comparable, adenosine triphosphate levels lower (4.8 µmol/g Hb vs. 6.1 µmol/g Hb), and 2,3‐diphosphoglycerate levels higher (10.3 µmol/g Hb vs 7.7 µmol/g Hb) at 6 hours after irradiation (product expiration time) compared to standard RBCs for IUT (n = 3). Anti‐A/‐B titers decreased substantially by the washing procedure.

CONCLUSION

RBCs for IUT can be prepared from 100‐ or 200‐mL WB donations, showing the potential of this new blood product to reduce donor exposure. A washing procedure is recommended to remove anti‐A/‐B.
Two‐Stage Rumen Cannulation Technique in Dairy Cows
Authors: Martineau Roger , Proulx Julien G. , Côrtes Cristiano , Brito Andre F. , Duffield Todd F.
Published: February 2015

Objective

To describe a 2‐stage rumen cannulation technique for dairy cows.

Study Design

Case series.

Animals

172 dairy cows from 2 research institutions.

Methods

The 2‐stage rumen cannulation technique first exteriorized a rumen segment within a wooden clamp, fixing the clamp to the skin with 6 mattress sutures. After 1 week, the necrotic rumen segment was removed, leaving a rumen fistula in which a 7.5 cm cannula was inserted. This was replaced by a 10 cm cannula a further 1 week later. The surgery took an average of 30 minutes. At least 1 assistant is required for the technique.

Results

The overall complication frequency was 7/172 (4%). One cow and 1 heifer aborted less than 10 days after surgery. Two late‐pregnant heifers died from peritonitis after insertion of the 7.5 cm cannula because of incomplete adhesion of the rumen to the abdominal wall. The exteriorized rumen segment slipped back in the abdomen in 3 cows but was successfully re‐clamped prior to insertion of the 7.5 cm cannula.

Conclusion

A high success rate was achieved with this 2‐stage cannulation technique. Postoperative complications were attributed to delayed adhesion of the rumen, perhaps because of stress‐related factors (e.g., transport, mixing with other animals, transition period).
Diversity of Plasmids and Antimicrobial Resistance Genes in Multidrug‐Resistant Escherichia coli Isolated from Healthy Companion Animals
Authors: Jackson C. R. , Davis J. A. , Frye J. G. , Barrett J. B. , Hiott L. M.
Published: February 2015

The presence and transfer of antimicrobial resistance genes from commensal bacteria in companion animals to more pathogenic bacteria may contribute to dissemination of antimicrobial resistance. The purpose of this study was to determine antimicrobial resistance gene content and the presence of genetic elements in antimicrobial resistant Escherichia coli from healthy companion animals. In our previous study, from May to August, 2007, healthy companion animals (155 dogs and 121 cats) from three veterinary clinics in the Athens, GA, USA area were sampled and multidrug‐resistant E. coli (n = 36; MDR, resistance to ≥2 antimicrobial classes) were obtained. Of the 25 different plasmid replicon types tested by PCR, at least one plasmid replicon type was detected in 94% (34/36) of the MDR E. coli; four isolates contained as many as five different plasmid replicons. Nine replicon types (FIA, FIB, FII, I2, A/C, U, P, I1 and HI2) were identified with FIB, FII, I2 as the most common pattern. The presence of class I integrons (intI) was detected in 61% (22/36) of the isolates with eight isolates containing aminoglycoside‐ and/or trimethoprim‐resistance genes in the variable cassette region of intI. Microarray analysis of a subset of the MDR E. coli (n = 9) identified the presence of genes conferring resistance to aminoglycosides (aac, aad, aph and strA/B), β‐lactams (ampC, cmy, tem and vim), chloramphenicol (cat), sulfonamides (sulI and sulII), tetracycline [tet(A), tet(B), tet(C), tet(D) and regulator, tetR] and trimethoprim (dfrA). Antimicrobial resistance to eight antimicrobials (ampicillin, cefoxitin, ceftiofur, amoxicillin/clavulanic acid, streptomycin, gentamicin, sulfisoxazole and trimethoprim‐sulfamethoxazole) and five plasmid replicons (FIA, FIB, FII, I1 and I2) were transferred via conjugation. The presence of antimicrobial resistance genes, intI and transferable plasmid replicons indicate that E. coli from companion animals may play an important role in the dissemination of antimicrobial resistance, particularly to human hosts during contact.
Chronic clenbuterol treatment compromises force production without directly altering skeletal muscle contractile machinery
Authors: Py G. , Ramonatxo C. , Sirvent P. , Sanchez A. M. J. , Philippe A. G. , Douillard A. , Galbès O. , Lionne C. , Bonnieu A. , Chopard A. , Cazorla O. , Lacampagne A. , Candau R. B.
Published: February 2015

Key points

Clenbuterol is an adrenergic receptor agonist known to induce skeletal muscle hypertrophy and a shift towards faster muscle fibres, when administered chronically at high doses.

However, when normalized to the muscle surface area, the increase in muscle force is no longer increased and even depressed.

We show that muscle contraction and relaxation force kinetics were significantly reduced particularly in fast contracting muscles.

We show that action potential‐elicited Ca2+ transients were depressed in the fast contracting muscle.

Our data show that chronic clenbuterol treatment reduces contractile efficiency, with altered contraction and relaxation kinetics, but without directly altering the contractile machinery. Lower Ca2+ release during contraction could partially explain these deleterious effects.

Clenbuterol is a β2‐adrenergic receptor agonist known to induce skeletal muscle hypertrophy and a slow‐to‐fast phenotypic shift. The aim of the present study was to test the effects of chronic clenbuterol treatment on contractile efficiency and explore the underlying mechanisms, i.e. the muscle contractile machinery and calcium‐handling ability. Forty‐three 6‐week‐old male Wistar rats were randomly allocated to one of six groups that were treated with either subcutaneous equimolar doses of clenbuterol (4 mg kg−1 day−1) or saline solution for 9, 14 or 21 days. In addition to the muscle hypertrophy, although an 89% increase in absolute maximal tetanic force (Po) was noted, specific maximal tetanic force (sPo) was unchanged or even depressed in the slow twitch muscle of the clenbuterol‐treated rats (P < 0.05). The fit of muscle contraction and relaxation force kinetics indicated that clenbuterol treatment significantly reduced the rate constant of force development and the slow and fast rate constants of relaxation in extensor digitorum longus muscle (P < 0.05), and only the fast rate constant of relaxation in soleus muscle (P < 0.05). Myofibrillar ATPase activity increased in both relaxed and activated conditions in soleus (P < 0.001), suggesting that the depressed specific tension was not due to the myosin head alteration itself. Moreover, action potential‐elicited Ca2+ transients in flexor digitorum brevis fibres (fast twitch fibres) from clenbuterol‐treated animals demonstrated decreased amplitude after 14 days (−19%, P < 0.01) and 21 days (−25%, P < 0.01). In conclusion, we showed that chronic clenbuterol treatment reduces contractile efficiency, with altered contraction and relaxation kinetics, but without directly altering the contractile machinery. Lower Ca2+ release during contraction could partially explain these deleterious effects.
Delayed-Decomposition Approach for Absolute Stability of Neutral-Type Lurie Control Systems With Time-Varying Delays
Authors: Liu Pin-Lin
Published: February 2015

The problem of absolute stability for a class of neutral-type Lurie control system with nonlinearity located in an infinite sector and in a finite one is investigated in this paper. Based on the delayed-decomposition approach (DDA), a new augmented Lyapunov functional is constructed and the delay dependent conditions for asymptotic stability are derived by applying an integral inequality approach (IIA) in terms of linear matrix inequalities (LMIs). Finally, numerical examples are provided to show that the proposed results significantly improve the allowed upper bounds of the delay size over some existing ones in the literature.
Low Speed Balancing of Flexible Rotors Considering Influences of Running Speeds
Authors: Tan S.-G. , Wang X.-X.
Published: February 2015

An investigation of the influences of running speeds to the low speed balance of flexible rotors is made in this paper and shows that the balancing weights obtained at the balance speeds can be corrected and nearly equal to that at the operation speed. So the theory of low speed balancing of flexible rotors can be used not only for flexible rotors with natural properties independent of running speeds, but also for those with natural properties dependent on running speeds.
An Improved Epicyclic Gearbox for Reduced and Controllable Sub-Synchronous Vibrations in Gas Turbogenerator Applications
Authors: Rakhit A. K.
Published: February 2015

An improvement is made to the design of epicyclic gearbox that limits the dynamic eccentricities of gearbox components. Gearboxes manufactured to the new design and tested, showed reduced levels of sub-synchronous vibrations at the turbine bearings. The in-situ balancing feature of the gearbox is also found to be very effective in reducing these vibrations further. The improved gearboxes not only assured the service life of the turbine bearings, but also increased the success rate of package testing the first time with substantial cost savings.
Numerical Simulation of Secondary Flow in Gas Turbine Disc Cavities, Including Conjugate Heat Transfer
Authors: Ho Y.-H. , Athavale M. M. , Forry J. M. , Hendricks R. C. , Steinetz B. M.
Published: February 2015

A numerical study of the flow and heat transfer in secondary flow elements of the entire inner portion of the turbine section of the Allison T-56/501D engine is presented. The flow simulation included the interstage cavities, rim seals and associated main path flows, while the energy equation also included the solid parts of the turbine disc, rotor supports, and stator supports. Solutions of the energy equations in these problems usually face the difficulty in specifications of wall thermal boundary conditions. By solving the entire turbine section this difficulty is thus removed, and realistic thermal conditions are realized on all internal walls. The simulation was performed using SCISEAL, an advanced 2D/3D CFD code for predictions of fluid flows and forces in turbomachinery seals and secondary flow elements. The mass flow rates and gas temperatures at various seal locations were compared with the design data from Allison. Computed gas flow rates and temperatures in the rim and labyrinth seal show a fair 10 good comparison with the design calculations. The conjugate heat transfer analysis indicates temperature gradients in the stationary intercavity walls, as well as the rotating turbine discs. The thermal strains in the stationary wall may lead to altered interstage labyrinth seal clearances and affect the disc cavity flows. The temperature, fields in the turbine discs also may lead to distortions that can alter the rim seal clearances. Such details of the flow and temperature fields are important in designs of the turbine sections to account for possible thermal distortions and their effects on the performance. The simulation shows that the present day CFD codes can provide the means to understand the complex flow field and thereby aid the design process.
The Prediction of the Tip Clearance Vortex Circulation and its Induced Flow Field in Axial Flow Machines
Authors: Nikolos I. K. , Douvikas D. I. , Papailiou K. D.
Published: February 2015

A model for the prediction of the leakage vortex circulation was developed, based on the assumption that the leakage jet flow enters as a whole the vortex core, increasing its radius and its moment of momentum in the direction of the vortex axis. Using the assumption that the leakage vortex has a solid body rotation, an expression was derived for the vortex circulation, which demonstrates that this circulation is proportional to the square root of the corresponding tip clearance height. This theoretical result is supported by the available experimental data for both compressors and turbines. A simple model was developed, which demonstrates the ability of the proposed theory to calculate the leakage vortex circulation, provided that the vortex trace is known.

A method for predicting the tip clearance effects in the flow field inside and downstream the blade passage, compatible with a meridional flow calculation procedure, has been developed by the authors. The method uses incompressible considerations and accounts for the calculation of the circumferentially mean deficit radial profiles of the various flow quantities. In the calculation procedure the tip clearance flow effects are considered as a modification to the basic flow, existing in the absence of tip clearance. The complete calculation procedure was used in order to calculate the leakage vortex circulation and the induced velocity field in various axial flow cases, with satisfactory results.
Thrust Reverser Catchers: Devices Which Enable Cyclic Testing Between Forward and Reverse Thrust
Authors: Adkins Richard C. , Sherwood Mike
Published: February 2015

Cyclic operation of engines between forward and reverse thrust configurations is a requirement of testing for Extended Twin Operations (ETOPS) certification. When these tests are conducted inside enclosed test cells it is then necessary to redirect the exhaust gases in order to return them to the cell exhaust ducting. This is done by specially designed catcher ducts which have undergone many years of development, due to the complicated nature of the flow. The paper discusses the features that have eventually made these devices successful and as such is intended as an aid to design.
A Simplified Scheme for Scheduling Multivariable Controllers and its Application to a Turbofan Engine
Authors: Garg Sanjay
Published: February 2015

A simplified scheme for scheduling multivariable controllers for robust performance over a wide range of plant operating points is presented. The approach consists of scheduling only the output matrix of a dynamic controller, thus significantly reducing the number of parameters to be scheduled. Given a robust controller at a nominal design point, designed such that it gives a stable closed-loop system at various off-design operating points, the parameters of the controller output matrix are optimized such that the closed-loop response at the off-design points closely matches the design point closed-loop response. The optimization problem formulation for the synthesis of controller scheduling gains is discussed. Results are presented for controller scheduling for a turbofan engine for a conceptual Short Take-Off and Vertical Landing aircraft. The simplified controller scheduling is shown to provide satisfactory response for engine models corresponding to significant gross thrust variations from the nominal design point.
SiC High Temperature Electronics for Next Generation Aircraft Controls Systems
Authors: Perkins John F. , Hopkins Richard H. , Brandt Charles D. , Agarwal Anant K. , Seshadri Suresh , Siergiej Richard R.
Published: February 2015

Several organizations, including Westinghouse, CREE, and ATM, as well as researchers in Japan and Europe, are working to develop SiC power devices for reliable, high power and high temperature environments in military, industrial, utility, and automotive applications. Other organizations, such as NASA Lewis and several universities, are also doing important basic work on basic SiC technology development. It has been recognized for two decades that the superior properties of SiC lead to range of devices with higher power, greater temperature tolerance, and significantly more radiation hardness than silicon or GaAs. This combination of superior thermal and electrical properties results in SiC devices that can operate at up to ten times the power density of Si devices for a given volume.

Recent research has focused on the development of vertical metal oxide semiconductor field effect transistor (VMOSFET) power device technology, and complementary high speed, temperature-tolerant rectifier-diodes for power applications. We are also evaluating applications for field control thyristors (FCT) and MOS turn-off thyristors (MTO). The technical issues to be resolved for these devices are also common to other power device structures. The present paper reviews the relative benefits of various power devices structures, with emphasis on how the special properties of SiC enhance the desirability of specific device configurations as compared to the Si-based versions of these devices. Progress in SiC material quality and recent power device research will be reviewed, and the potential for SiC-based devices to operate at much higher temperatures than Si-based devices, or with enhanced reliability at higher temperatures will be stressed. We have already demonstrated 1000V breakdown, current densities of 1 kA/cm2, and measurements up to 400°C in small diodes. The extension of this work will enable the implementation of highly distributed aircraft power control systems, as well as actuator and signal conditioning electronics for next generation engine sensors, by permitting electronic circuits, sensors and smart actuators to be mounted on or at the engine.
High Temperature Power Electronics for Gas Turbine Engine Applications
Authors: Grzybowski Richard R. , Foyt A. George
Published: February 2015

The drive power requirements for several representative actuator applications are discussed, and the possibilities of meeting those requirements with conventional silicon electronics, and also with higher temperature capability electronics are presented. For all the usual drive circuits, both normally-off power transistors and conventional diodes are essential. Silicon devices can meet these requirements, if the electronics can be maintained near room temperature. If not, then devices based on other materials systems, such as silicon carbide, are needed. Basic material properties suggest that these devices can be capable of controlling large power levels, much larger than for silicon. However, these devices are in the very early stage of development, and have been demonstrated at only low power levels. Finally, the development of efficient blue light emitting diodes in the gallium nitride materials system is discussed. This resulting investment in this system may enhance the development of higher power, high temperature nitride-based devices, offering an exciting alternate to silicon carbide.
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Measurements for Combustor With Acoustically Controlled Primary Zone
Authors: Vermeulen Peter J. , Ramesh Venkataramanayya
Published: February 2015

Successful NOx measurements at the end of the primary zone of s small tubular combustor of conventional gas turbine design, employing acoustically controlled primary zone air-jet mixing processes, have been made at scaled 1/4 and 1/5 load operating conditions. Testing at 1/5 load significantly increased the effective strength of the acoustic drive which strongly improved the mixing by the acoustically driven primary zone air-jets. The acoustic drive caused partial blockage of the combustor primary zone air flow. This increased the equivalence ratio and the gas temperature, and made the gas temperature distribution more uniform, except for lean conditions at 1/5 load, in the plane of the NOx, measurements. This explained the measured greater NOx, “with-drive”, and the distinctly more uniform NOx, distribution which confirmed that mixing was acoustically augmented. The acoustically produced changes were greater at 1/5 load. The acoustic drive significantly changed the combustor operating characteristic so far as mean NOx was concerned, and under lean conditions st 1/5 load mean NOx was reduced indicating that a value of 10 ppm is possible (a 50% reduction).
Measurements in a Transitional Boundary Layer With Görtler Vortices
Authors: Volino Ralph J. , Simon Terrence W.
Published: February 2015

The laminar-turbulent transition process has been documented in a concave-wall boundary layer subject to low (0.6%) free-stream turbulence intensity. Transition began at a Reynolds number, Rex (based on distance from the leading edge of the test wall), of 3.5×105 and was completed by 4.7×105. The transition was strongly influenced by the presence of stationary, streamwise, Görtler vortices. Transition under similar conditions has been documented in previous studies, but because concave-wall transition tends to be rapid, measurements within the transition zone were sparse. In this study, emphasis is on measurements within the zone of intermittent flow. Twenty-five profiles of mean streamwise velocity, fluctuating streamwise velocity, and intermittency have been acquired at five values of Rex, and five spanwise locations relative to a Görtler vortex. The mean velocity profiles acquired near the vortex downwash sites exhibit inflection points and local minima. These minima, located in the outer part of the boundary layer, provide evidence of a “tilting” of the vortices in the spanwise direction. Profiles of fluctuating velocity and intermittency exhibit peaks near the locations of the minima in the mean velocity profiles. These peaks indicate that turbulence is generated in regions of high shear, which are relatively far from the wall. The transition mechanism in this flow is different from that on flat walls, where turbulence is produced in the near-wall region. The peak intermittency values in the profiles increase with Rex, but do not follow the “universal” distribution observed in most flat-wall, transitional boundary layers. The results have applications whenever strong concave curvature may result in the formation of Görtler vortices in otherwise 2-D flows. Because these cases were run with a low value of free-stream turbulence intensity, the flow is not a replication of a gas turbine flow. However, the results do provide a base case for further work on transition on the pressure side of gas turbine airfoils, where concave curvature effects are combined with the effects of high free-stream turbulence and strong streamwise pressure gradients, for they show the effects of embedded streamwise vorticity in a flow that is free of high-turbulence effects.
The Influence of Outlet Stator Part Surface Roughness on the Performance of a Very Low Flow Coefficient Centrifugal Compressor Stage
Authors: Paroubek Jan , Cyrus Václav , Kynčl Jiři
Published: February 2015

An aerodynamic investigation of the influence of outlet stator part (vaneless diffuser and return channel) surface roughness on aerodynamic performance of a very low flow coefficient centrifugal stage has been carried out. The stage with design inlet flow coefficient 0.007 was tested within the range of stage Mach number Mu2=0.5–1.1. Then the surface quality of outlet stator part was improved and the tests have been repeated. Aerodynamic performance and losses in both vaneless diffuser and return channel with de-swirl vanes were investigated. The values of isentropic head coefficient increased while those of loss coefficient decreased nearly in the whole range of characteristics in the stage with improved surface quality. The detailed pressure recovery in vaneless diffuser in vicinity of design point measured and calculated by the performance prediction method is compared and discussed. The nonsteady flow phenomena were also investigated. The change of dynamic stability limit by improving of surface quality was observed.
Redesigning a Generator Set for Improved Maintenance
Authors: Masincup William E. , Halsey Jack , Russom Dennis
Published: February 2015

Early in the DDG 51 shipbuilding program, it became apparent that the Ship Service Gas Turbine Generators (SSGTGs) were not optimized for maintenance. A redesign effort was undertaken as a joint effort of Allison Engine Company, the Aegis Program Manager and the Naval Sea Systems Command to improve the maintainability of the unit. The paper examines the process used in the effort and details the specific improvements made over the course of the program.
A New Approach for a Low-Cooled Ceramic Nozzle Vane
Authors: Gutmann C. , Schulz A. , Wittig S.
Published: February 2015

At the Institute for Thermal Turbomachinery, University of Karlsruhe (ITS) a new methodology for designing thermally loaded ceramic components based on numerical analyses of the thermal and structural behaviour is developed. Major issues are an effective optimization of the geometry and an assessment of the load.

To reduce thermally induced stresses in shell structures exposed to hot gas flow a precise description of the major influencing parameters is required. Based on these relations a thermal optimization of the component is possible. Moreover, the compensation of thermal strains and the adjustment of local stiffnesses for reducing the tensile stresses and the failure probability has to be considered.

In designing a first stage vane of a stationary gas turbine the proposed guidelines are verified. The advantages of a systematic approach are demonstrated. The multi-purpose numerical procedures using the guidelines allow an adjustment of the shape to thermally and mechanically induced loads and offer new possibilities to meet the specific demands of ceramic materials.