bluuebunny/crossref_metadata_2025 huggingface dataset:
IMPACT ON FIRMS OF THE USE OF KNOWLEDGE EXTERNAL SOURCES: A SYSTEMATIC REVIEW OF THE LITERATURE
Authors: Vivas Carlos , Barge‐Gil Andrés
Published: September 2014

This study summarizes the main conclusions from a systematic review of the empirical literature regarding the impact on firms of the use of knowledge external sources (universities, research institutes and knowledge intensive business services). With the aim to organize the literature, we classify the different works according to the research question addressed: (i) which firms use knowledge external sources?; (ii) Do firms using knowledge external sources achieve better results?; And (iii) which firms benefit the most from using knowledge external sources? Stylized facts are that larger, more R&D intensive and high tech firms are more likely to use knowledge external sources and that use of knowledge external sources is associated to firms higher technical results. Less attention has been paid to the third question and evidence is not conclusive. Several recommendations for future research emerge. First, to take in greater consideration methodological issues so that potential biases in the results caused by sample selection and endogeneity are handled properly. Second, to pay more attention to heterogeneous outcomes. Third, to use continuous indicators of depth and breadth of links allowing for non‐linear relationships and fourth, to extend evidence for developing countries and service industries.
Predicting Risk‐Mitigating Behaviors From Indecisiveness and Trait Anxiety: Two Cognitive Pathways to Task Avoidance
Authors: McNeill Ilona M. , Dunlop Patrick D. , Skinner Timothy C. , Morrison David L.
Published: September 2014

Past research suggests that indecisiveness and trait anxiety may both decrease the likelihood of performing risk‐mitigating preparatory behaviors (e.g., preparing for natural hazards) and suggests two cognitive processes (perceived control and worrying) as potential mediators. However, no single study to date has examined the influence of these traits and processes together. Examining them simultaneously is necessary to gain an integrated understanding of their relationship with risk‐mitigating behaviors. We therefore examined these traits and mediators in relation to wildfire preparedness in a two‐wave field study among residents of wildfire‐prone areas in Western Australia (total N = 223). Structural equation modeling results showed that indecisiveness uniquely predicted preparedness, with higher indecisiveness predicting lower preparedness. This relationship was fully mediated by perceived control over wildfire‐related outcomes. Trait anxiety did not uniquely predict preparedness or perceived control, but it did uniquely predict worry, with higher trait anxiety predicting more worrying. Also, worry trended toward uniquely predicting preparedness, albeit in an unpredicted positive direction. This shows how the lack of performing risk‐mitigating behaviors can result from distinct cognitive processes that are linked to distinct personality traits. It also highlights how simultaneous examination of multiple pathways to behavior creates a fuller understanding of its antecedents.
The Relation of Pro‐Sociality to Self‐Esteem: The Mediational Role of Quality of Friendships
Authors: Zuffianò Antonio , Eisenberg Nancy , Alessandri Guido , Luengo Kanacri Bernadette Paula , Pastorelli Concetta , Milioni Michela , Caprara Gian Vittorio
Published: September 2014

The present longitudinal study examined the role of quality of friendship in mediating the relation of pro‐sociality to self‐esteem over time. Participants were 424 Italian young adults (56% females) assessed at two waves (Mage = 21.1 at Time 1; Mage = 25 at Time 2). An autoregressive cross‐lagged panel model was used to test the mediational model. Self‐ and friend‐report measures of pro‐sociality, quality of friendship, and self‐esteem were included in the analyses. Results were in line with the hypothesized paths, with quality of friendship mediating the relation of pro‐sociality to later self‐esteem above and beyond its high stability. Self‐esteem, in turn, predicted pro‐sociality 4 years later. Overall, the present findings support the potential benefits of behaving pro‐socially for an actor in terms of increased perceived self‐worth and also expand previous work by outlining the specific mediational role of the quality of friendships. The theoretical and practical implications of these results are discussed.
Evaluating Tablet Computers as a Survey Tool in Rural Communities
Authors: Newell Steve M. , Logan Henrietta L. , Guo Yi , Marks John G. , Shepperd James A.
Published: September 2014

Purpose

Although tablet computers offer advantages in data collection over traditional paper‐and‐pencil methods, little research has examined whether the 2 formats yield similar responses, especially with underserved populations. We compared the 2 survey formats and tested whether participants’ responses to common health questionnaires or perceptions of usability differed by survey format. We also tested whether we could replicate established paper‐and‐pencil findings via tablet computer.

Methods

We recruited a sample of low‐income community members living in the rural southern United States. Participants were 170 residents (black = 49%; white = 36%; other races and missing data = 15%) drawn from 2 counties meeting Florida's state statutory definition of rural with 100 persons or fewer per square mile. We randomly assigned participants to complete scales (Center for Epidemiologic Studies Depression Inventory and Regulatory Focus Questionnaire) along with survey format usability ratings via paper‐and‐pencil or tablet computer. All participants rated a series of previously validated posters using a tablet computer. Finally, participants completed comparisons of the survey formats and reported survey format preferences.

Findings

Participants preferred using the tablet computer and showed no significant differences between formats in mean responses, scale reliabilities, or in participants’ usability ratings.

Conclusions

Overall, participants reported similar scales responses and usability ratings between formats. However, participants reported both preferring and enjoying responding via tablet computer more. Collectively, these findings are among the first data to show that tablet computers represent a suitable substitute among an underrepresented rural sample for paper‐and‐pencil methodology in survey research.
ON WEIGHTED PORTMANTEAU TESTS FOR TIME‐SERIES GOODNESS‐OF‐FIT
Authors: Gallagher Colin M. , Fisher Thomas J.
Published: September 2014

Recent work in the literature has shown weighted variants of the classic portmanteau test for time series can be more powerful in many situations. In this article, we study the asymptotic distribution of weighted sums of the squared residual autocorrelations where both the sample size n and maximum lag of the statistic m grow large. Several weighting schemes are introduced, including a data‐adaptive statistic in which the weights are determined by a function of the sample partial autocorrelations. These statistics can provide more power than other portmanteau tests found in the literature and are much less sensitive to the choice of the maximum correlation lag. The efficacy of the proposed methods is further demonstrated through an analysis of Australian red wine sales.
Effect of Work‐Related Factors on Lower Urinary Tract Symptoms in Nurses and Secretaries
Authors: KAYA Yeliz , KAYA Coşkun , BASESKIOGLU Barbaros , OZERDOĞAN Nebahat , YENILMEZ Aydın , DEMIRÜSTÜ Canan
Published: September 2014

Objective

The objective of the present study was to examine the relationship between work‐related factors and lower urinary tract symptoms (LUTS) and to emphasize the vicious circle between symptoms and work conditions.

Methods

The Turkish version of the Nurse Bladder Survey was used to estimate the prevalence of LUTS and to assess the relationship between individual characteristics, personal habits and work‐related factors in nurses and secretaries who were working in Eskisehir Osmangazi University Hospital. The Turkish version of the Short Form 36 Health Survey was used to assess the nurses' and secretaries' health‐related quality of life (HRQL).

Results

Of the 281 women who participated in the study, 218 (77.5%) and 63 (22.5%) were nurses and secretaries, respectively. There were no significant differences in personal habits and work‐related factors between the nurses and secretaries. Of the study participants, 121 (43.1%) experienced at least one type of LUTS. There were no significant differences in the prevalence of any type of LUTS between the two groups. Only the mean scores of social functioning were significantly different for nurses and secretaries on the other aspects of HRQL in the SF‐36. When the nurses with LUTS and the secretaries with LUTS were compared, the secretaries had a greater score on the general health domain than nurses.

Conclusion

There is a vicious circle between symptoms and work conditions. To prevent the working women from harmful effects of this circle, the employers should be aware of this health problem; working conditions should be improved; educational programs for LUTS should be organized and the working women should be encouraged to go to the health providers to seek treatment when the symptoms occurred.
Induction of Bladder Overactivity by Nerve Growth Factor in Testes in Rats: Possible Neural Crosstalk Between the Testes and Urinary Bladder
Authors: YOSHIOKA Katsuro , TANAHASHI Masayuki , TAKEDA Masahiro , MASUDA Noriyuki
Published: September 2014

Objectives

To clarify the pathophysiological factor underlying neural crosstalk among pelvic organs, we investigated the possible role of nerve growth factor (NGF) in the neural crosstalk between the testes and urinary bladder.

Methods

Nerve growth factor (10, 30, and 100 µg/mL) or saline was injected into the testes of male Wistar rats. The change in bladder capacity via cystometry and duration of spontaneous scratching behavior induced by NGF in conscious rats was measured. The effects of pretreatment with capsaicin on NGF‐induced changes in bladder capacity and behavior were examined. Further, we evaluated the effect of analgesics, indomethacin and morphine, and pretreatment with compound 48/80 on NGF‐induced scratching behavior to elucidate the mechanism of the behavior.

Results

Injection of saline into the testes had no effect on bladder capacity or behavior. However, an injection of NGF (30 and 100 µg/mL) reduced bladder capacity, which was regarded as bladder overactivity, and evoked scratching behavior in a dose‐dependent manner. Pretreatment with capsaicin inhibited NGF‐induced bladder overactivity and scratching behavior. Neither indomethacin nor pretreatment with compound 48/80 affected the scratching behavior, but morphine inhibited the behavior.

Conclusions

The present study provides evidence of a possible new role of NGF in the testes regarding the activation of testicular primary afferent neurons mediated by capsaicin‐sensitive C‐fibers, which evokes bladder overactivity via neural crosstalk between the testes and the urinary bladder as well as testicular pain.
Microclimatic differentiation of gene pools in theLobaria pulmonariasymbiosis in a primeval forest landscape
Authors: Nadyeina Olga , Dymytrova Lyudmyla , Naumovych Anna , Postoyalkin Sergyi , Werth Silke , Cheenacharoen Saran , Scheidegger Christoph
Published: September 2014

Population genetics of the tree‐colonizing lichenLobaria pulmonariawere studied in the largest primeval beech forest ofEurope, covering 10 000 ha. During an intensive survey of the area, we collected 1522 thallus fragments originating from 483 trees, which were genotyped with eight mycobiont‐ and 14 photobiont‐specific microsatellite markers. The mycobiont and photobiont ofL. pulmonariawere found to consist of two distinct gene pools, which are co‐existing within small areas of 3–180 ha in a homogeneous beech forest. The small‐scale distribution pattern of the symbiotic gene pools show habitat partitioning of lineages associated with either floodplains or mountain forests. Using approximate Bayesian computation (ABC), we dated the divergence of the two fungal gene pools ofL. pulmonariaas theEarlyPleistocene. Both fungal gene pools survived thePleistocene glacial cycles in theCarpathians, although possibly in climatically different refugia. Fungal diversification prior to these cycles and the selection of photobionts with different altitudinal distributions explain the current sympatric, but ecologically differentiated habitat partitioning ofL. pulmonaria. In addition, the habitat preferences of the mycobiont are determined by other factors and are rather independent of those of the photobiont at the landscape level. The distinct gene pools should be considered evolutionarily significant units and deserve specific conservation priorities in the future, for example gene pool A, which is aPliocene relict.
Population genomics of the killer whale indicates ecotype evolution in sympatry involving both selection and drift
Authors: Moura Andre E. , Kenny John G. , Chaudhuri Roy , Hughes Margaret A. , J. Welch Andreanna , Reisinger Ryan R. , de Bruyn P. J. Nico , Dahlheim Marilyn E. , Hall Neil , Hoelzel A. Rus
Published: September 2014

The evolution of diversity in the marine ecosystem is poorly understood, given the relatively high potential for connectivity, especially for highly mobile species such as whales and dolphins. The killer whale (Orcinus orca) has a worldwide distribution, and individual social groups travel over a wide geographic range. Even so, regional populations have been shown to be genetically differentiated, including among different foraging specialists (ecotypes) in sympatry. Given the strong matrifocal social structure of this species together with strong resource specializations, understanding the process of differentiation will require an understanding of the relative importance of both genetic drift and local adaptation. Here we provide a high‐resolution analysis based on nuclear single‐nucleotide polymorphic markers and inference about differentiation at both neutral loci and those potentially under selection. We find that all population comparisons, within or among foraging ecotypes, show significant differentiation, including populations in parapatry and sympatry. Loci putatively under selection show a different pattern of structure compared to neutral loci and are associated with gene ontology terms reflecting physiologically relevant functions (e.g. related to digestion). The pattern of differentiation for one ecotype in the North Pacific suggests local adaptation and shows some fixed differences among sympatric ecotypes. We suggest that differential habitat use and resource specializations have promoted sufficient isolation to allow differential evolution at neutral and functional loci, but that the process is recent and dependent on both selection and drift.
IS OUTPUT PERFORMANCE ALL ABOUT THE RESOURCES? A FUZZY‐SET QUALITATIVE COMPARATIVE ANALYSIS OF STREET‐LEVEL BUREAUCRATS IN SWITZERLAND
Authors: THOMANN EVA
Published: September 2014

This article refines Lipsky's assertion that lacking resources negatively affects output performance. It uses fuzzy‐set Qualitative Comparative Analysis to analyse the nuanced interplay of contextual and individual determinants of the output performance of veterinary inspectors as street‐level bureaucrats in Switzerland. Moving ‘beyond Lipsky’, the study builds on recent theoretical contributions and a systematic comparison across organizational contexts. Against a widespread assumption, output performance is not all about resources. The impact of perceived available resources hinges on caseloads, which prove to be more decisive. These contextual factors interact with individual attitudes emerging from diverse public accountabilities. The results contextualize the often‐emphasized importance of worker–client interaction. In a setting where clients cannot escape the interaction, street‐level bureaucrats are not primarily held accountable by them. Studies of output performance should thus consider gaps between what is being demanded of and offered to street‐level bureaucrats, and the latter's multiple embeddedness.
Healing of Granulomatous Skin Changes in Ataxia‐Telangiectasia After Treatment with Intravenous Immunoglobulin and Topical Mometasone 0.1% Ointment
Authors: Privette Emily D. , Ram Gita , Treat James R. , Yan Albert C. , Heimall Jennifer R.
Published: September 2014

Ataxia‐telangiectasia (AT) is a rare autosomal recessive disorder characterized by faulty DNA damage repair. The disease affects multiple systems and is noted to be particularly difficult to diagnose in children because of the wide spectrum of clinical presentations. We present an unusual case of a child in whom the primary cutaneous manifestation of AT was noninfectious cutaneous caseating granulomas. A 3‐year‐old girl presented to the emergency department with ataxia, poor growth, and multiple ulcerated plaques on both upper extremities that had been present for 2 years. She had two prolonged hospitalizations and underwent extensive examination to identify an etiology for the skin lesions. She was diagnosed with AT after immunology examinaton and genetic testing. Outpatient intravenous immunoglobulin (IVIG) therapy was initiated and she was prescribed twice‐daily mometasone 0.01% ointment under occlusion. After 6 weeks on this regimen her lesions had completely healed. Twenty‐two cases of AT have been reported in which patients presented with cutaneous granulomas. This report demonstrates the first reported case in which the granulomatous skin lesions of AT healed after aggressive application of topical steroids with concurrent IVIG therapy, without oral steroids. A brief review of cutaneous granulomas in the setting of immunodeficiency is also presented.
A practical target recognition system for close range photogrammetry
Authors: Shortis Mark R. , Seager James W.
Published: September 2014

This paper presents details of a coded target system that employs polar coordinate transformation and segment matching to automatically recognise and identify targets in digital images. The code system is based on a square surrounding the central circular target and is described at a level of detail that would allow the system to be readily duplicated. Pre‐detection processes, developed to improve the success rate under unfavourable conditions, and the tests conducted to validate a correct target match, are described. Finally, the paper includes some examples of the use of the coded targets, drawn from a variety of calibration and measurement applications.
Stereo‐imaging network design for precise and dense 3d reconstruction
Authors: Ahmadabadian Ali Hosseininaveh , Robson Stuart , Boehm Jan , Shortis Mark
Published: September 2014

This paper presents a novel stereo‐imaging network design strategy comprising four steps: datum definition, optimum distance estimation, candidate camera position generation, and lastly clustering and selection of vantage viewpoints. An approximate 3D mesh model of an object from a quick low‐cost system is used in the first step of the method. An ellipsoid is fitted to the rough model in order to find a suitable imaging distance regarding range‐ and visibility‐related constraints for a stereopair. Next, a set of viewpoints is provided taking into account the ellipsoid and the calculated distance. Finally, camera positions and orientations are defined by clustering and choosing the vantage viewpoints. A system, called “imaging network designer” (IND), has been developed based on this method and is evaluated with two different tests. Results show that IND can provide an imaging network, which fulfils the expected precision for the entire object.
Enhanced expression of Toll‐like receptors 2 and 4, but not 9, in spleen tissue from patients with visceral leishmaniasis
Authors: Kumar R. , Singh O. P. , Gautam S. , Nylen S. , Sundar S.
Published: September 2014

Toll‐like receptor (TLR) signalling is involved in first‐line defence against Leishmania parasites by triggering NF‐κB activation and downstream production of proinflammatory cytokines. Experimental models of visceral leishmaniasis (VL) support a protective role for TLRs 2, 4 and 9 in host immune responses to Leishmania infection. There are limited data available on expression of these TLRs in human VL, particularly in sites of infection, such as the spleen. This study aimed to determine whether the expression of mRNA encoding the expression of TLRs 2, 4 and 9 was altered in VL and compare expression patterns in splenic biopsies and peripheral blood mononuclear cells.
Efficacy of paced breathing for insomnia: Enhances vagal activity and improves sleep quality
Authors: Tsai H. J. , Kuo Terry B. J. , Lee Guo‐She , Yang Cheryl C. H.
Published: September 2014

Fourteen self‐reported insomniacs (SRI) and 14 good sleepers (GS) had their cardiac neuronal activity assessed by heart rate variability (HRV) under controlled respiration at a slow frequency rate of 0.1 Hz, and a forced rate of 0.2 Hz during daytime rest. Nighttime sleep was measured by polysomnography. The SRI showed depressed high frequency power of HRV compared to the GS. An increased total power of HRV was observed among the SRI during slow, paced breathing compared with spontaneous breathing and 0.2 Hz. Sleep onset latency, number of awakenings, and awakening time during sleep were decreased and sleep efficiency was increased if SRI practiced slow, paced breathing exercises for 20 min before going to sleep. Our results indicate that there is autonomic dysfunction among insomniacs, especially in relation to vagal activity; however, this decreased vagal activity can be facilitated by practicing slow, paced breathing, thereby improving sleep quality.
Support for the interruption and protection hypotheses of prepulse inhibition of startle: Evidence from a modified Attention Network Test
Authors: Blumenthal Terry D. , Reynolds J. Zachary , Spence Tamara E.
Published: September 2014

The startle response may interrupt information processing (interruption hypothesis), and prepulse inhibition of startle (PPI) may protect that processing from interruption (protection hypothesis). These hypotheses were tested by measuring startle eyeblinks during an Attention Network Test (ANT), a combined flanker and cue reaction time (RT) task that measures the efficiency of multiple attentional networks. ANT trials with and without startle stimuli presented in the interval between the visual cue (prepulse) and target were compared. Results showed that the startle stimulus served as an alerting stimulus, speeding RT in the ANT. However, this reaction time speeding was most pronounced on trials with no startle response (100% PPI). This suggests that the alerting effect of the startle stimulus was attenuated by the startle response, and that PPI decreased the degree of this interference, in support of the interruption and protection hypotheses.
Toward a ‘Catholic’ Reading of Kierkegaard
Authors: Furnal Joshua
Published: September 2014

Historically, some Catholic readers have been suspicious of Kierkegaard's writings; viewing him as an irrational Protestant irreconcilably at odds with Catholic thought. Nevertheless, the unexpected yet favorable mention of Kierkegaard in John Paul II's Fides et Ratio is an indication that Kierkegaard's writings are not so easily dismissed. One may be justified in asking: what account can be given to explain such a shift in how the Catholic reception of Kierkegaard changes from a polemical rejection to a papal endorsement during the 20th century? In this review essay, I will explore some recent Kierkegaard research that provides – or at least, provides some of the groundwork for – a positive ‘Catholic’ reading of Kierkegaard. Space does not permit an exhaustive exposition of each book, so I will highlight the salient features of each to underscore a new trend that is emerging in Kierkegaard studies.
God's Own Story? German Theology and Its Nineteenth‐Century Readers
Authors: Ledger‐Lomas Michael
Published: September 2014

This review essay discusses two recent monographs on nineteenth‐century German theology and its transnational reception. The books under review assess attempts by German theologians to present their discipline as a science, which required them to present its subject matter as at once purely historical and of absolute significance for humanity. The result was an attractive but inherently unstable discipline, which oscillated between idealist and critical objectives and historical and systematic modes of argument. Its reception in the United States demonstrates both its multifaceted character, which appealed to theologians from a range of traditions, and also the way in which engagement with Germany offered theologians a means of modernizing and sometimes challenging the doctrinal assumptions and scholarly methods of those traditions.
The ‘Omnipresent’ Augustine
Authors: Toom Tarmo
Published: September 2014

This review article explores a new indispensable reference work on the reception of Augustine. It offers an overview of its content, structure, and methodology, as well as a critical assessment of its overall contribution to the study of Augustine. Goethe once remarked that, in the world, there are just a few voices, yet so many echoes. Augustine is definitely among the ‘few voices’, which have provoked all manner of friendly and unfriendly echoes. It is particularly important to realize that, apart from explicit citations and references in western literature, Augustine has also profoundly shaped medieval and modern culture through the subtle dissemination of his ideas into various spheres of life. This reference work not only provides a description of the current state of the reception of Augustine, but also adds the new results of the diligent work of the contributing researchers and identifies several topics that still need to be investigated.
Incipient vertical traction carpets within collapsed sinkhole fills
Authors: Broughton Paul L.
Published: September 2014

Small vertically oriented traction carpets are reported from the collapsed sandy fills of 100 m deep Devonian limestone sinkholes underlying the Lower Cretaceous Athabasca oil sands deposit in north‐eastern Alberta, Western Canada. Dissolution of 100 m of underlying halite salt beds caused cataclysmic collapse of the sinkhole floors and water saturated sinkhole sand fills to descend very rapidly. Turbulent currents flushed upper sinkhole fills of friable sandstone blocks and disaggregated sand and quartz pebble for tens of metres. Laminar deposits with inverse grading accumulated as many as six to eight curvilinear entrained pebble streaks, 10 to 30 cm long, vertically impinged against the sides of descending collapse blocks. These deposits were initiated as vertically oriented early stage traction carpets that interlocked fine sand grains and inversely graded overlying pebbles entrained below the dilute overlying turbulent flows. Vortexes that flushed these sinkhole fills and induced these depositional processes may have lasted only seconds before the very rapid descents abruptly halted. Some of the fabrics were suspended vertically in‐place and preserved from unlocking and obliteration. These small fabrics provide insight into the instability and ephemeral character of the transition from strong gravity‐driven grain falls to very early stages of traction carpet formation. These short‐lived deposits of very thin sand layers resulted from sufficient incipient frictional freezing that grain interlocking overcame, however briefly, the strong gravity drives of the vertical falls that would have otherwise dispersed grains and obliterated any organized fabric patterns. Tenuous frictionally locked grains were also suspended at the centres of hyperbolic grain fall flows that briefly developed between turbulent flow eddies, some of which were fortuitously preserved. Some of these suspended grain locking zones passed downward onto the relatively more stable surfaces of the rapidly descending block surfaces. The morphogenesis of these early stage traction carpets differ from more fully developed deposits elsewhere because of their short‐lived transport, dynamic instability and vertical orientation.
Supralinear dendritic Ca2+ signalling in young developing CA1 pyramidal cells
Authors: Pohle Jörg , Bischofberger Josef
Published: September 2014

Key points

Because intracellular Ca2+ is important for activity‐dependent growth and development, we studied action potential (AP)‐evoked dendritic Ca2+ influx and Ca2+ buffering in developing rat CA1 pyramidal cells during the first 1–4 weeks after birth.

We show for the first time that active dendritic backpropagation of APs generates large Ca2+ transients in pyramidal cell dendrites even after the first postnatal week.

The amplitude of Ca2+ transients at 1 week is similar to that at 4 weeks because a four‐fold upregulation of calcium influx per AP is balanced by a similar increase in endogenous Ca2+ buffer capacity during this period.

The calcium extrusion after APs was about five times slower at 1 week than at 4 weeks, resulting in a slower decay in young cells and a more effective temporal summation during brief bursts of APs.

During continuous theta‐burst firing, dendritic calcium concentration was up to three‐fold larger in animals aged 1 week than in those aged 4 weeks, generated via an activity‐dependent slow‐down of Ca2+ extrusion, which may allow Ca2+‐dependent control of growth and development with a large dynamic range.

Although Ca2+ is critically important in activity‐dependent neuronal development, not much is known about the regulation of dendritic Ca2+ signals in developing neurons. Here, we used ratiometric Ca2+ imaging to investigate dendritic Ca2+ signalling in rat hippocampal pyramidal cells during the first 1–4 weeks of postnatal development. We show that active dendritic backpropagation of Nav channel‐dependent action potentials (APs) evoked already large dendritic Ca2+ transients in animals aged 1 week with amplitudes of ∼150 nm, similar to the amplitudes of ∼160 nM seen in animals aged 4 weeks. Although the AP‐evoked dendritic Ca2+ load increased about four times during the first 4 weeks, the peak amplitude of free Ca2+ concentration was balanced by a four‐fold increase in Ca2+ buffer capacity κs (∼70 vs. ∼280). Furthermore, Ca2+ extrusion rates increased with postnatal development, leading to a slower decay time course (∼0.2 s vs. ∼0.1 s) and more effective temporal summation of Ca2+ signals in young cells. Most importantly, during prolonged theta‐burst stimulation dendritic Ca2+ signals were up to three times larger in cells at 1 week than at 4 weeks of age and much larger than predicted by linear summation, which is attributable to an activity‐dependent slow‐down of Ca2+ extrusion. As Ca2+ influx is four‐fold smaller in young cells, the larger Ca2+ signals are generated using four times less ATP consumption. Taken together, the data suggest that active backpropagations regulate dendritic Ca2+ signals during early postnatal development. Remarkably, during prolonged AP firing, Ca2+ signals are several times larger in young than in mature cells as a result of activity‐dependent regulation of Ca2+ extrusion rates.
Potential Impact of Renewable Fuels and Technological Innovations on Global Air Traffic Emissions Development by 2050
Authors: Wolters Florian , Schaefer Martin , von der Bank Ralf
Published: September 2014

The aviation industry has set ambitious reduction targets for future air traffic emissions to compensate for the environmental impact of increasing air transport. Besides technological innovation in the fields of aircraft and engine technology, alternative fuels from non-petroleum feedstock are often seen as having long-term potential to offer reductions in aviation’s greenhouse gas emissions. The current paper studies the effects of potential emission reduction measures up to the year 2050, taking technology developments as well as renewable fuel scenarios into account. The individual impacts of both contributions are assessed in terms of fuel burn, direct CO2 emissions, and life cycle CO2eq emissions. The results are compared to the agreed mid and long term reductions targets, i.e. carbon-neutral growth by 2020 and halving CO2 emissions by 2050.

Future air traffic emissions are evaluated based on one reference scenario and three technology scenarios, derived from the ICAO global fuel burn forecast and Flightpath 2050 technology improvement goals. Four renewable fuel penetration scenarios are considered and the impact of alternative renewable fuels in terms of Synthetic Paraffinic Kerosene (SPK) on fuel burn and direct CO2 emissions are taken into consideration. Moreover, to account for the fuels’ life cycle emissions three different life cycle CO2eq emission reduction potentials scenarios are applied.

This study provides a quantitative view on exponential growth of aviation fleet CO2 emissions. The potential of individual contributions are explicitly highlighted and potential developments in air traffic emissions are quantified. The results show that in addition to significant efficiency improvements in aircraft and engine technology, a high renewable fuel share will be required to compensate for steady air traffic growth and to achieve carbon neutral growth from 2020 onwards and a 50% CO2eq emission reduction by 2050.
New Design Approach for Pitot-Tube Jet Pump
Authors: Meyer J. , Daróczy L. , Thévenin D.
Published: September 2014

In this report the diffusor geometry for a Pitot-Tube Jet pump (PTJ pump) is optimized, using 3D, steady CFD methods (software: ANSYS Fluent) as well as mesh morphing (software: Sculptor). The design point is Q = 16 m3/h. A complex optimization loop is set up, which takes geometric constraints, as well as manufacturing limits into account. The optimization is multi-objective and best practice guidelines are derived for future diffusor designs with respect to the reduction of total pressure losses and the diffusor displacement in the fluid of the rotor cavity. Both, advantages and disadvantages, are listed and evaluated.
Numerical Investigation of Pressure Fluctuation on the Volute of a Backward Curved Blade Centrifugal Fan
Authors: Zhang Jianhua , Chu Wuli , Wu Yanhui , Zhang Haoguang , Dong Xingjie
Published: September 2014

The pressure fluctuations on the volute surface induced by internal unsteady flow are the important sources of fan casing vibration and noise generation. In this paper, a three-dimensional and unsteady flow of a whole impeller-volute structure have been carried out by using commercial CFX code in order to obtain the wall pressure fluctuations on the volute of a large scale centrifugal fan (especially in the vicinity of volute tongue). The two important different flow rates have been simulated, the best efficiency point (BEP) and 130 percent of the BEP (1.3 × BEP), multi-domain structure grids have been applied in all the domains of current simulations. The pressure fluctuations of setting locations on the volute have been obtained by this method. Characteristics of these fluctuations in time and frequency domains were mainly analyzed. The results showed that the amplitudes of these pressure fluctuations over the volute changed with the flow rates variation. The blade passing frequency and their second harmonic frequency were observed clearly, and an important peak presented at the blade passing frequency (BPF). The amplitude of BPF has related with the position of the volute. On the circumferential direction of the volute, the highest values appeared in the vicinity of volute tongue; on the axial position, the peak value was discovered near to impeller shrouds. All the calculation results have been compared to the experimental results showing a good agreement.
Combined Vibration and Temperature Analysis for Condition Monitoring of Aero-Engines
Authors: Nembhard A. D. , Sinha J. K.
Published: September 2014

An earlier combined vibration and temperature analysis technique for rotating machinery fault diagnosis produced good results. This was, however, applied to a rotating machinery experimental rig operating at a constant speed. In the current study, using a similar approach, vibration data and temperature measurements obtained at different steady state rotating speeds for different fault conditions namely; crack, misalignment and rub, are fused together in a single analysis step. The objective in this case is to develop a computationally efficient fault diagnosis technique that can exploit data measured at different rotating speeds. The result obtained is an easily interpreted diagrammatical representation that shows clear discrimination between the different fault conditions tested and the healthy condition, thus offering the potential for practical application on variable speed machinery such as aero-engines.
Passive Noise Reduction for a Contra-Rotating Fan
Authors: Wang C. , Huang L.
Published: September 2014

There has been renewed interest in the contra-rotating (CR) fan configuration in aviation and other applications where size and weight are important design factors. Contra-rotation recovers swirl energy compared with the single-rotor design, but this advantage is not fully harnessed due to, perhaps, the issue of noise. This study explores passive noise reduction for a small, axial-flow, contra-rotating fan with perforated trailing-edge for the upstream rotor and perforated leading-edge for the downstream rotor. The fan is designed with simple velocity triangle analyses which are checked by 3D flow computations. The aerodynamic consequence and the acoustic benefit of such perforated blading are investigated experimentally. The results show that there is a reduction of total pressure compared with the baseline CR fan at the same rotating speeds, but this is easily compensated for by slightly raising the rotating speeds. A reduction of 6∼7 dB in overall noise is achieved for the same aerodynamic output, although there is a moderate noise increase in the high frequency range of 12.5∼15.0 kHz due to blade perforations. The effect of inter-rotor separation distance is also investigated for the baseline design. A clear critical distance exists below which the increased spacing shows clear acoustic benefits.
Multipoint Multi-Objective Optimization of a Low Solidity Circular Cascade Diffuser in Centrifugal Blowers
Authors: Sakaguchi Daisaku , Ishida Masahiro , Hayami Hiroshi , Mueller Lasse , Alsalihi Zuheyr , Verstraete Tom
Published: September 2014

In radial compressors or blowers, a low solidity circular cascade diffuser (LSD) is one of the effective devices to improve the pressure recovery at design flow rate while guaranteeing a wide operating range. The improvement is mainly attributed to the so called secondary flow effect, which reduces the flow separation on the LSD blade at small flow rates. However, it is very difficult to find out the effective shape of the blade in order to promote this secondary flow effect. In this paper, a multipoint and multi-objective optimization technique is applied to design the LSD blade of a centrifugal blower. The optimization method has been developed at the von Karman Institute for Fluid Dynamics (VKI), which makes use of an evolutionary algorithm, a metamodel as a rapid exploration tool, and a high fidelity 3D Navier-Stokes solver.

The optimization is aiming at improving the static pressure coefficient at design point and at low flow rate condition while constraining the slope of the lift coefficient curve. Seven detailed design parameters describing the shape and position of the LSD vane were introduced, e.g. the radial spacing between impeller exit and the LSD leading edge, the radial chord length and the mean camber angle distribution of the LSD blade with five control points. Moreover, a small tip clearance of the LSD blade was applied in order to activate and to stabilize the secondary flow effect at small flow rate condition. The optimized LSD blade has an extended operating range of 114 % towards smaller flow rate as compared to the baseline design without deteriorating the diffuser pressure recovery at design point. The diffuser pressure rise and operating flow range of the optimized LSD blade are experimentally verified. It is found that the optimized LSD blade shows good improvement of the blade loading in the whole operating range, while at small flow rate the flow separation on the LSD blade has been successfully suppressed by the secondary flow effect. This is fully corresponding to the CFD predictions and demonstrates the effectiveness of the optimization methodology, by limiting the experimental testing to only two geometries.
Lip Separation and Inlet Flow Distortion Control in Ducted Fans Used in VTOL Systems
Authors: Akturk Ali , Camcı Cengiz
Published: September 2014

This paper describes a novel ducted fan inlet flow conditioning concept that will significantly improve the performance and controllability of ducted fan systems operating at high angle of attack. High angle of attack operation of ducted fans is very common in VTOL (vertical take off and landing) UAV systems. The new concept that will significantly reduce the inlet lip separation related performance penalties in the edgewise/forward flight zone is named DOUBLE DUCTED FAN (DDF). The current concept uses a secondary stationary duct system to control inlet lip separation related momentum deficit at the inlet of the fan rotor occurring at elevated edgewise flight velocities. The DDF is self-adjusting in a wide edgewise flight velocity range and its corrective aerodynamic effect becomes more pronounced with increasing flight velocity due to its inherent design properties. Most axial flow fans are designed for an axial inlet flow with zero or minimal inlet flow distortion. The DDF concept is proven to be an effective way of dealing with inlet flow distortions occurring near the lip section of any axial flow fan system, especially at high angle of attack. In this present paper, a conventional baseline duct without any lip separation control feature is compared to two different double ducted fans named DDF CASE-A and DDF CASE-B via 3D, viscous and turbulent flow computational analysis. Both hover and edgewise flight conditions are considered. Significant relative improvements from DDF CASE-A and DDF CASE-B are in the areas of vertical force (thrust) enhancement, nose-up pitching moment control and recovery of fan through-flow mass flow rate in a wide horizontal flight range.
Ultra-Short Nacelles for Low Fan Pressure Ratio Propulsors
Authors: Peters Andreas , Spakovszky Zoltán S. , Lord Wesley K. , Rose Becky
Published: September 2014

As the propulsor fan pressure ratio (FPR) is decreased for improved fuel burn, reduced emissions and noise, the fan diameter grows and innovative nacelle concepts with short inlets are required to reduce their weight and drag. This paper addresses the uncharted inlet and nacelle design space for low-FPR propulsors where fan and nacelle are more closely coupled than in current turbofan engines. The paper presents an integrated fan-nacelle design framework, combining a spline-based inlet design tool with a fast and reliable body-force-based approach for the fan rotor and stator blade rows to capture the inlet-fan and fan-exhaust interactions and flow distortion at the fan face. The new capability enables parametric studies of characteristic inlet and nacelle design parameters with a short turn-around time. The interaction of the rotor with a region of high streamwise Mach number at the fan face is identified as the key mechanism limiting the design of short inlets. The local increase in Mach number is due to flow acceleration along the inlet internal surface coupled with a reduction in effective flow area. For a candidate short-inlet design with length over diameter ratio L/D = 0.19, the streamwise Mach number at the fan face near the shroud increases by up to 0.16 at cruise and by up to 0.36 at off-design conditions relative to a long-inlet propulsor with L/D = 0.5. As a consequence, the rotor locally operates close to choke resulting in fan efficiency penalties of up to 1.6 % at cruise and 3.9 % at off-design. For inlets with L/D < 0.25, the benefit from reduced nacelle drag is offset by the reduction in fan efficiency, resulting in propulsive efficiency penalties. Based on a parametric inlet study, the recommended inlet L/D is suggested to be between 0.25 and 0.4. The performance of a candidate short inlet with L/D = 0.25 was assessed using full-annulus unsteady RANS simulations at critical design and off-design operating conditions. The candidate design maintains the propulsive efficiency of the baseline case and fuel burn benefits are conjectured due to reductions in nacelle weight and drag compared to an aircraft powered by the baseline propulsor.
Enhanced Robust Design Simulation and Application to Engine Cycle and Technology Design
Authors: Sands Jonathan S. , Perullo Christopher A. , Kestner Brian K. , Mavris Dimitri N.
Published: September 2014

Increases in computing power have enabled designers to efficiently use Monte Carlo simulation to perform robust design analyses of engine systems. Unfortunately, the designer is now faced with the problem of being able to generate more data than he is capable of analyzing or understanding in any tractable manner. Traditional filtered Monte Carlo methods involve creating surrogate model representations (such as Artificial Neural Networks) of a physics based model in order to rapidly generate tens of thousands of model responses as design and technology input parameters are randomly varied within user defined distributions. The downside to this approach is that the designer is often faced with a large design space with which he must perform a significant amount of post processing to arrive at probabilities of meeting design requirements.

This research enhances the traditional filtered Monte Carlo robust design approach by regressing surrogate responses of joint confidence intervals for metric responses of interest. Fitting surrogate responses of probabilistic confidence intervals rather than the raw response data changes the problem the engineer is able to answer. Using the new approach the question can be better phrased in terms of the probability of meeting certain requirements. For example, one will be able to ask, “What engine overall pressure ratio is needed to achieve a 90% chance of reaching a 25% reduction in TSFC from the current state of the art?” The more traditional approach does not have the ability to include confidence in the process without significant post-processing.

The process will be demonstrated using a two-spool axi-centrifugal turboshaft architecture modeled using the Numerical Propulsion System Simulation (NPSS) program. The new robust design process will be used to demonstrate the probabilistic impacts of both technology and design variables on choosing a cycle that is robust to both growth in mission requirements and changes in anticipated technology levels as the design matures. More specifically, the research will present engine cycle variables including component pressure ratios and temperatures that provide for high probability of meeting notional system level requirements, such as ESFC, under different levels of technology uncertainty. Technology uncertainty will be defined in terms of available material properties and component efficiency.