bluuebunny/crossref_metadata_2025 huggingface dataset:
Reward prediction error does not explain movement selectivity in DMS-projecting dopamine neurons
Authors: Lee Rachel S. , Mattar Marcelo G. , Parker Nathan F. , Witten Ilana B. , Daw Nathaniel D.
Published: October 2018

Although midbrain dopamine (DA) neurons have been thought to primarily encode reward prediction error (RPE), recent studies have also found movement-related DAergic signals. For example, we recently reported that DA neurons in mice projecting to dorsomedial striatum are modulated by choices contralateral to the recording side. Here, we introduce, and ultimately reject, a candidate resolution for the puzzling RPE vs movement dichotomy, by showing how seemingly movement-related activity might be explained by an action-specific RPE. By considering both choice and RPE on a trial-by-trial basis, we find that DA signals are modulated by contralateral choice in a manner that is distinct from RPE, implying that choice encoding is better explained by movement direction. This fundamental separation between RPE and movement encoding may help shed light on the diversity of functions and dysfunctions of the DA system.
Computational Analysis of Single Nucleotide polymorphisms (SNPs) in Human TCell Acute Lymphocytic Leukemia Protein 1 (TAL1) Gene/Comprehensive Study
Authors: Shantier Shaza W. , Elmansi Hashim E. , Elnnewery Mihad E. , Osman Hind K. , Alhassan Isam-Aldin A. , Abdelrhman Fatima A. , Yagaub Ahmed A. , Yousif Einas M. , Abdalla Alaa I. , Elamin Rawan A. , Fadol Howina S. , Fadl Alla Afra A. , Hassan Mohamed A.
Published: October 2018

Background

TAL1is a proto-oncogene whose distorted modifications in committed T-cell Precursors is related with the development of T-ALL, it also found to be related to many other human hematological diseases such as lymphoblastic lymphoma, immunodeficiency 18, acute myeloid leukemia and diamond-blackfan Anemia.

Objectives

This study aims to predict the effect of nsSNPs onTAL1protein structure function

Methods

Retrieved nSNPs in the coding and3’UTRregions were analyzed using different in silico tools. Interactions ofTAL1with functionally similar genes were investigated using Genemania. Post-translational modifications in several sites of the protein were also investigated.

Results

Out of ninety nsSNPs identified, only eight were found damaging to protein function of which one is located in the basis helix-loop-helix domain (bHLH). Two SNPs were anticipated by PolymiRTs to prompt disturbance or creation of miR binding sites.

Conclusion

The present study is the first ever computational analysis ofTAL1’s nsSNPs hence this effort might be of help in the near future for inventing early diagnostic and therapeutic measures for T-ALL
Setting Starting Level for a Trial of an Biofilm-Disrupting Adjuvant
Authors: Adams Braden , Lodder Robert A.
Published: October 2018

Combination therapy is beneficial treatment modality for multiple diseases. Cinnamon oil may be an advantageous agent in a number of combination therapies as cinnamon oil has antibacterial activity. Cinnamon oil has also been shown to be effective against biofilm cultures of Streptococcus mutans and Lactobacillus plantarum. Cinnamomum osmophloeum inhibits planktonic cultures of many gram-positive and gram-negative bacteria, including MRSA (methicillin-resistant Staphylococcus aureus). Subjecting S. epidermidis to cinnamon oil eliminates planktonic cells or staphylococci in biofilms. Cinnamon oil is an essential oil used throughout the food industry because of its pleasant and distinctive aroma. The purpose of this study is to estimate the amount of exposure to cinnamon through selected foods in the United States in order to propose an initial target level for pharmacokinetic studies of a novel combination drug.
Targeted memory reactivation during sleep to strengthen memory for arbitrary pairings
Authors: Vargas Iliana M , Schechtman Eitan , Paller Ken A
Published: October 2018

A powerful way to investigate memory consolidation during sleep utilizes acoustic stimulation to reactivate memories. In multiple studies, Targeted Memory Reactivation (TMR) using sounds associated with prior learning improved later memory, as in recalling locations where objects previously appeared. In the present experiment, we examined whether a variant of the same technique could strengthen memory for the locations of pairs of objects. Each sound was naturally connected to one object from each pair, but we hypothesized that both memories could be improved with TMR. We first asked participants to memorize each of 50 pairs of objects by associating the two objects with each other and with the sound of one of the objects (e.g., cat-meow). Next, objects were presented in unique locations on a grid. Participants learned these locations in an adaptive procedure. During an afternoon nap, 25 of the sounds were quietly presented. In memory tests given twice before and twice after the nap, participants heard the sound for each object pair and were asked to recall the name of the second object and the locations of both objects. Forgetting scores were calculated using the mean difference between pre-nap and post-nap spatial recall errors. We found less forgetting after the nap for cued compared to non-cued objects. Additionally, the extent of forgetting tended to be similar for the two members of each pair, but only for cued pairs. Results thus substantiate the potential for sounds to reactivate spatial memories during sleep and thereby improve subsequent recall performance, even for multiple objects associated with a single sound and when participants must learn a novel sound-object association.
Phasic arousal suppresses biases in mice and humans across domains of decision-making
Authors: de Gee J. W. , Tsetsos K. , Schwabe L. , Urai A.E. , McCormick D. A. , McGinley M. J. , Donner T. H.
Published: October 2018

Decisions are often made by accumulating ambiguous evidence over time. The brain’s arousal systems are activated during such decisions. In previous work in humans, we showed that evoked responses of arousal centers during decisions are reported by rapid dilations of the pupil, and predict a suppression of biases in the accumulation of decision-relevant evidence (de Gee et al. 2017). Here, we show that this arousal-related suppression in decision bias acts on both conservative and liberal biases, and generalizes across species (humans / mice), sensory systems (visual / auditory), and domains of decision-making (perceptual / memory-based). In challenging sound-detection tasks, the impact of spontaneous or experimentally induced choice biases was reduced under high arousal. Similar bias suppression occurred when evidence was drawn from memory. All these behavioral effects were explained by reduced evidence accumulation biases. Our results pinpoint a general principle of the interplay between phasic arousal and decision-making.
Translation factor mRNA granules direct protein synthetic capacity to regions of polarized growth
Authors: Pizzinga Mariavittoria , Bates Christian , Lui Jennifer , Forte Gabriella , Morales-Polanco Fabián , Linney Emma , Knotkova Barbora , Wilson Beverley , Solari Clara A. , Berchowitz Luke E. , Portela Paula , Ashe Mark P.
Published: October 2018

mRNA localization serves key functions in localized protein production making it critical that the translation machinery itself is present at these locations. Here we show that translation factor mRNAs are localized to distinct granules within yeast cells. In contrast to many mRNP granules, such as P-bodies and stress granules, which contain translationally repressed mRNAs, these granules harbor translated mRNAs under active growth conditions. The granules require Pablp for their integrity and are inherited by developing daughter cells in a She2p/ She3p dependent manner. These results point to a model where roughly half the mRNA for certain translation factors are specifically directed in granules toward the tip of the developing daughter cell where protein synthesis is most heavily required, which has particular implications for filamentous forms of growth. Such a feedforward mechanism would ensure adequate provision of the translation machinery where it is to be needed most over the coming growth cycle.

This study shows that mRNAs encoding a range of translation factors are localized to granules that get transported into the yeast daughter cell using the She2p/She3p machinery. This likely supports an intensification of protein synthetic activity to facilitate apical polarized growth.
Jackknife model averaging prediction methods for complex phenotypes with gene expression levels by integrating external pathway information
Authors: Yu Xinghao , Xiao Lishun , Zeng Ping , Huang Shuiping
Published: October 2018

Motivation

In the past few years many novel prediction approaches have been proposed and widely employed in high dimensional genetic data for disease risk evaluation. However, those approaches typically ignore in model fitting the important group structures or functional classifications that naturally exists in genetic data.

Methods

In the present study, we applied a novel model averaging approach, called Jackknife Model Averaging Prediction (JMAP), for high dimensional genetic risk prediction while incorporating KEGG pathway information into the model specification. JMAP selects the optimal weights across candidate models by minimizing a cross-validation criterion in a jackknife way. Compared with previous approaches, one of the primary features of JMAP is to allow model weights to vary from 0 to 1 but without the limitation that the summation of weights is equal to one. We evaluated the performance of JMAP using extensive simulation studies and compared it with existing methods. We finally applied JMAP to five real cancer datasets that are publicly available from TCGA.

Results

The simulations showed that, compared with other existing approaches, JMAP performed best or are among the best methods across a range of scenarios. For example, among 14 out of 16 simulation settings with PVE=0.3, JMAP has an average of 0.075 higher prediction accuracy compared with gsslasso. We further found that in the simulation the model weights for the true candidate models have much smaller chances to be zero compared with those for the null candidate models and are substantially greater in magnitude. In the real data application, JMAP also behaves comparably or better compared with the other methods for both continuous and binary phenotypes. For example, for the COAD, CRC and PAAD data sets, the average gains of predictive accuracy of JMAP are 0.019, 0.064 and 0.052 compared with gsslasso.

Conclusion

The proposed method JMAP is a novel method that can provide more accurate phenotypic prediction while incorporating external useful group information.
Transposon accumulation lines uncover histone H2A.Z-driven integration bias towards environmentally responsive genes
Authors: Quadrana Leandro , Etcheverry Mathilde , Gilly Arthur , Caillieux Erwann , Madoui Mohammed-Amin , Guy Julie , Silveira Amanda Bortolini , Engelen Stefan , Baillet Victoire , Wincke Patrick , Aury Jean-Marc , Colot Vincent
Published: October 2018

Inherited transposition events are important drivers of genome evolution but because transposable element (TE) mobilization is usually rare, its impact on the creation of genetic variation remains poorly characterized. Here, we used a population of A. thaliana epigenetic recombinant inbred lines (epiRILs) to characterize >8000 de novo insertions produced by several TEs families also active in nature. Integration was strongly biased towards genes, with evident deleterious effects. Biases were TE family-specific and associated with distinct chromatin features. Notably, we demonstrate that the histone variant H2A.Z guides the preferential integration of Ty1/Copia LTR-retrotransposons within environmentally responsive genes and that this guiding function is evolutionary conserved. Finally, we uncover an important role for epigenetic silencing in exacerbating or alleviating the effects of TE insertions on target genes. These findings establish chromatin as a major determinant of the spectrum and functional impact of TE-generated mutations, with important implications for adaptation and evolution.
Alternative interaction sites in the influenza A virus nucleoprotein mediate viral escape from the importin-α7 mediated nuclear import pathway
Authors: Resa-Infante Patricia , Bonet Jaume , Thiele Swantje , Alawi Malik , Oliva Baldo , Gabriel Gülsah
Published: October 2018

Influenza A viruses are able to adapt to restrictive conditions due to their high mutation rates. Here, we addressed the question by which mechanisms influenza A viruses may escape restriction by the cellular importin-α7 protein, a component of the nuclear import machinery required for avian-mammalian adaptation and replicative fitness in human cells. Therefore, we assessed viral evolution in mice lacking the importin-α7 gene. Here, we show that particularly three mutations occur with high frequency in the viral NP protein (G102R, M105K and D375N) in a specific structural area uponin vivoadaptation. Moreover, our findings suggest that the adaptive NP mutations mediate viral escape from importin-α7 requirement likely due to the utilization of alternative interaction sites in NP beyond the classical nuclear localization signal and importin-α isoforms. However, viral escape from importin-α7 is, at least in part, associated with reduced replicative fitness in human cells.
Collective radioresistance of T47D breast carcinoma cells is mediated by a Syncytin-1 homologous protein
Authors: Chignola Roberto , Sega Michela , Molesini Barbara , Baruzzi Anna , Stella Sabrina , Milotti Edoardo
Published: October 2018

It is generally accepted that radiotherapy must target clonogenic cells, i.e., those cells in a tumour that have self-renewing potential. Focussing on isolated clonogenic cells, however, may lead to an underestimate or even to an outright neglect of the importance of biological mechanisms that regulate tumour cell sensitivity to radiation. We develop a new statistical and experimental approach to quantify the effects of radiation on cell populations as a whole. In our experiments, we change the proximity relationships of the cells by culturing them in wells with different shapes, and we find that the radiosensitivity of T47D human breast carcinoma cells in tight clusters is different from that of isolated cells. Molecular analyses show that T47D cells express a Syncytin-1 homologous protein (SyHP). We observe that SyHP translocates to the external surface of the plasma membrane of cells killed by radiation treatment. The data support the fundamental role of SyHP in the formation of intercellular cytoplasmic bridges and in the enhanced radioresistance of surviving cells. We conclude that complex and unexpected biological mechanisms of tumour radioresistance take place at the cell population level. These mechanisms may significantly bias our estimates of the radiosensitivity of breast carcinomasin vivoand thereby affect treatment plans, and they call for further investigations.
Analysis of an HIV model with post-treatment control
Authors: Wang Shaoli , Xu Fei
Published: October 2018

Recent investigation indicated that latent reservoir and immune impairment are responsible for the post-treatment control of HIV infection. In this paper, we simplify the disease model with latent reservoir and immune impairment and perform a series of mathematical analysis. We obtain the basic infection reproductive number R0 to characterize the viral dynamics. We prove that when R0 < 1, the uninfected equilibrium of the proposed model is globally asymptotically stable. When R0 > 1, we obtain two thresholds, the post-treatment immune control threshold and the elite control threshold. The model has bistable behaviors in the interval between the two thresholds. If the proliferation rate of CTLs is less than the post-treatment immune control threshold, the model does not have positive equilibria. In this case, the immune free equilibrium is stable and the system will have virus rebound. On the other hand, when the proliferation rate of CTLs is greater than the elite control threshold, the system has stable positive immune equilibrium and unstable immune free equilibrium. Thus, the system is under elite control.

Author summary

In this article, we use mathematical model to investigate the combined effect of latent reservoir and immune impairment on the post-treatment control of HIV infection. By simplifying an HIV model with latent reservoir and immune impairment, and performing mathematical analysis, we obtain the post-treatment immune control threshold and the elite control threshold for the HIV dynamics when R0 > 1. The HIV model displays bistable behaviors in the interval between the two thresholds. We illustrate our results using both mathematical analysis and numerical simulation. Our result is consistent with recent medical experiment. We show that patient with low proliferation rate of CTLs may undergo virus rebound, and patient with high proliferation rate of CTLs may obtain elite control of HIV infection. We perform bifurcation analysis to illustrate the infection status of patient with the variation of proliferation rate of CTLs, which potentially explain the reason behind different outcomes among HIV patients.
Wolbachia endosymbionts subvert the endoplasmic reticulum to acquire host membranes without triggering ER stress
Authors: Fattouh Nour , Cazevieille Chantal , Landmann Frédéric
Published: October 2018

The reproductive parasite Wolbachia are the most common endosymbionts on earth, present in a plethora of arthropod species. They have been introduced into mosquitos to successfully prevent the spread of vector-borne diseases, yet the strategies of host cell subversion underlying their obligate intracellular lifestyle remain to be explored in depth in order to gain insights into the mechanisms of pathogen-blocking. Like some other intracellular bacteria, Wolbachia reside in a host-derived vacuole in order to replicate and escape the immune surveillance. Using here the pathogen-blocking Wolbachia strain from Drosophila melanogaster, introduced into two different Drosophila cell lines, we show that Wolbachia subvert the endoplasmic reticulum to acquire their vacuolar membrane and colonize the host cell at high density. Wolbachia redistribute the endoplasmic reticulum to increase contact sites, and time lapse experiments reveal tight coupled dynamics suggesting important signalling events or nutrient uptake. They however do not affect the tubular or cisternal morphologies. A fraction of endoplasmic reticulum becomes clustered, allowing the endosymbionts to reside in between the endoplasmic reticulum and the Golgi apparatus, possibly modulating the traffic between these two organelles. Gene expression analyses and immunostaining studies suggest that Wolbachia achieve persistent infections at very high titers without triggering endoplasmic reticulum stress or enhanced ERAD-driven proteolysis, suggesting that amino acid salvage is achieved through modulation of other signalling pathways.

Author summary

Wolbachia are a genus of intracellular bacteria living in symbiosis with millions of arthropod species. They have the ability to block the transmission of arboviruses when introduced into mosquito vectors, by interfering with the cellular resources exploited by these viruses. Despite the biomedical interest of this symbiosis, little is known about the mechanisms by which Wolbachia survive and replicate in the host cell. We show here that the membrane composing the Wolbachia vacuole is acquired from the endoplasmic reticulum, a central organelle required for protein and lipid synthesis, and from which originates a vesicular trafficking toward the Golgi apparatus and the secretory pathway. Wolbachia modify the distribution of this organelle to increase their interactions with this source of membrane and likely of nutrients as well. In contrast to some intracellular pathogenic bacteria, the effect of Wolbachia on the cell homeostasis does not induce a stress on the endoplasmic reticulum. One of the consequences of such a stress would be an increased proteolysis used to relieve the cell from an excess of misfolded proteins. Incidentally, this shows that Wolbachia do not acquire amino acids from the host cell through this strategy.
Major Domestication-Related Phenotypes inIndicaRice Are Due to Loss of miRNA-Mediated Laccase Silencing
Authors: Swetha Chenna , Basu Debjani , Pachamuthu Kannan , Tirumalai Varsha , Nair Ashwin , Prasad Melvin , Shivaprasad P. V.
Published: October 2018

Domestication of rice (Oryza sativa) included conversion of perennial wild species with few seeds to short plants that produced abundant seeds. Most domestication-associated changes were due to variations in transcription factors and other key proteins such as enzymes. Here, we show that multiple yield-related traits associated with indica rice domestication are linked to micro (mi) RNA-mediated regulation. Analysis of small (s) RNA data sets from cultivated indica rice lines, a few landraces, and two wild relatives of rice revealed the presence of abundant 22-nucleotide (nt) reads in wild relatives that mapped to miR397 precursors. miR397 was expressed at very high levels in wild relatives and at negligible levels in high-yielding cultivated lines. In its genera-specific form of 22-nt, miR397 targeted mRNAs encoding laccases that decayed and induced robust secondary cascade silencing in wild species that required RNA-dependent RNA polymerase 6. In wild species of rice, reduced expression of laccases resulted in low lignification. As expected, overexpression of miR397 induced de-domestication phenotypes. At least 26 uncharacterized QTLs previously implicated in rice yield overlapped with laccases and miR397 genes. These results suggest that miRNAs contribute to rice domestication-associated phenotypes.
Dynamics of soft nanoparticle suspensions at hard X-ray FEL sources below the radiation-damage threshold
Authors: Lehmkühler Felix , Valerio Joana , Sheyfer Dina , Roseker Wojciech , Schroer Martin A. , Fischer Birgit , Tono Kensuke , Yabashi Makina , Ishikawa Tetsuya , Grübel Gerhard
Published: October 2018

The application of X-ray photon correlation spectroscopy (XPCS) at free-electron laser (FEL) facilities enables, for the first time, the study of dynamics on a (sub-)nanometre scale in an unreached time range between femtoseconds and seconds. For soft-matter materials, radiation damage is a major limitation when going beyond single-shot applications. Here, an XPCS study is presented at a hard X-ray FEL on radiation-sensitive polymeric poly(N-isopropylacrylamide) (PNIPAM) nanoparticles. The dynamics of aqueous suspensions of densely packed silica-PNIPAM core-shell particles and a PNIPAM nanogel below the radiation-damage threshold are determined. The XPCS data indicate non-diffusive behaviour, suggesting ballistic and stress-dominated heterogeneous particle motions. These results demonstrate the feasibility of XPCS experiments on radiation-sensitive soft-matter materials at FEL sources and pave the way for future applications at MHz repetition rates as well as ultrafast modes using split-pulse devices.
The first spontaneous resolution of a sulfoxide: Dianin's compound analogue, (R)-4-(4-hydroxyphenyl)-2,2,4-trimethylthiachroman-1-oxide
Authors: Gall James H. , White J. Derek , MacNicol David D. , Frampton Christopher S.
Published: October 2018

The title sulfoxide, C18H20O2S, was prepared by controlled oxidation of thia-Dianin's compound using hydrogen peroxide in glacial acetic acid. On recrystallization from glacial acetic acid, it was found to form unsolvated, spontaneously resolved crystals, the initial crystal structure analysis revealing the presence of both sulfoxide epimers in the crystal. On multiple recrystallization a single epimer was observed, with crystallization occurring in the unchanged orthorhombic space group P212121, with Z′ = 1. The molecule possesses a distal conformation, referring to the juxtaposition of the p-hydoxyphenyl substituent with respect to its syn-related methyl group, with the sulfoxide oxygen atom anti to the aromatic substituent. The molecular packing features O—H...O hydrogen bond chains running parallel to the b axis of the unit cell.
Crystal structure of 5,15-dihexyl-5,15-dihydrobenzo[2,1-b:4,3-c′]dicarbazole hexane 0.375-solvate
Authors: Zhang Dingchao , Shi Longqiang , Liu Zhi , Li Li , Hu Zhenhao , Cui Deliang , Yang Jing
Published: October 2018

The title compound, C38H40N2·0.375C6H14, crystallizes in the monoclinic space groupP21/cand has a host–guest structure with the helicene molecules forming a porous structure and molecules of hexane inserted into the holes. The dihedral angles between the two carbazole sections of the right- and left-handed helicenes are 27.44 (3) and 25.63 (3)°, respectively. There are no classical π–π interactions or hydrogen-bonding interactions present between adjacent molecules in the crystal structure. The hexane solvent molecule shows positional disorder.
The methanol sesquisolvate of sodium naproxen
Authors: Kriegner Helene , Weil Matthias , Jones Matthew J.
Published: October 2018

The asymmetric unit of the methanol solvate of sodium naproxen, systematic name: sodium (2S)-2-(6-methoxynaphthalen-2-yl)propanoate methanol sesquisolvate, Na+·C14H13O3
−·1.5CH3OH, comprises two formula units of the molecular salt and three methanol molecules. One of the sodium cations exhibits a coordination number of six and is bonded to three carboxylate O atoms and three methanol OH groups whereas the second sodium cation has a coordination number of seven, defined by five carboxylate O atoms and two methanol OH groups. Both coordination polyhedra around the sodium cations are considerably distorted. The two types of cations are bridged into polymeric chains extending parallel to [010]. This arrangement is stabilized by intrachain O—H...O hydrogen bonds between methanol ligands as donor and carboxylate O atoms as acceptor groups. The hydrophobic 6-methoxynaphthyl moieties flank the hydrophilic sodium oxygen chains into ribbons parallel to [010]. There are no noticeable intermolecular interactions between these ribbons. One of the 6-methoxynaphthyl moieties is disordered over two sets of sites in a 0.723 (3):0.277 (3) ratio.
Bis(pyrrolidinium) hexachloridostannate: a redetermination
Authors: Gotoh Kazuma , Ishida Hiroyuki
Published: October 2018

The crystal structure of the title compound, (C4H10N)2[SnCl6], has been redetermined at 180 K. All atoms were located with higher precision than the previous structure determined at room temperature [Ishida et al. (2000). J Mol. Struct. 524, 95–103]. In the crystal, the SnIV atom is located on a special position of site symmetry 2/m and is coordinated by six Cl atoms in a pseudo-octahedral geometry. Of the six Cl atoms, two equivalent axial atoms lie on the mirror plane [Sn—Cl = 2.4281 (6) Å] and the other four equivalent equatorial atoms lie on general positions [Sn—Cl = 2.4285 (4) Å]. The N atom of the pyrrolidinium cation lies on a mirror plane and the other atoms of the cation are disordered over two sites with respect to the mirror plane. Each component of the disordered five-membered rings adopts a twist conformation. The cations and anions are connected via N—H...Cl hydrogen bonds, forming a tape-like structure propagating along [010].
Hybridization of training aircraft with real world flight profiles
Authors: Donateo Teresa , Totaro Roberto
Published: October 2018

Purpose

The purpose of this paper is to analyze real-world flight data of a piston engine training aircraft collected from an internet-based radar service, along with wind data provided by a weather forecast model, and to use such data to design a hybrid electric power system.

Design/methodology/approach

The modeling strategy starts from the power demand imposed by a real-world wind-corrected flight profile, where speed and altitude are provided as functions of time, and goes through the calculation of the efficiency of the powertrain components when they meet such demand. Each component of the power system and, in particular, the engine and the propeller, is simulated as a black box with an efficiency depending on the actual working conditions. In the case of hybrid electric power system, the battery charging and discharging processes are simulated with the Shepherd model.

Findings

The variability of power demand and fuel consumption for a training aircraft is analyzed by applying the proposed methodology to the Piper PA-28-180 Cherokee, a very popular aircraft used for flight training, air taxi and personal use. The potentiality of hybridization is assessed by analyzing the usage of the engine over more than 90 flights. A tentative sizing of a hybrid electric power system is also proposed. It guarantees a fuel saving of about 5%.

Originality/value

The scientific contribution and the novelty of the investigation are related to the modeling methodology, which takes into account real-world flight conditions, and the application of hybridization to a training aircraft.
Satellite angular motion classification for active on-orbit debris removal using robots
Authors: Seweryn Karol , Sasiadek Jurek Z.
Published: October 2018

Purpose

This paper aims to present a novel method for identification and classification of rotational motion for uncontrolled satellites. These processes are shown in context of close proximity orbital operations. In particular, it includes a manipulator arm mounted on chaser satellite and used to capture target satellites. In such situations, a precise extrapolation of the target’s docking port position is needed to determine the manipulator arm motion. The outcome of this analysis might be used in future debris removal or servicing space missions.

Design/methodology/approach

Nonlinear, and in some special cases, chaotic nature of satellite rotational motion was considered. Four parameters were defined: range of motion toward docking port, dominant frequencies, fractal dimension of the motion and its time dependencies.

Findings

The qualitative analysis was performed for presented cases of spacecraft rotational motion and for each case the respective parameters were calculated. The analysis shows that it is possible to detect the type of rotational motion.

Originality/value

A novel procedure allowing to estimate the type of satellite rotational motion based on fractal approach was proposed.
Aerodynamics analysis of rotor’s impact on the aircraft in the tandem wing configuration
Authors: Figat Marcin
Published: October 2018

Purpose

This paper aims to present the results of aerodynamic calculation of the aircraft in tandem wing configuration called VTOL. A presented vehicle combines the capabilities of the classic aircraft and helicopters. The aircraft is equipped with two pairs of tilt-rotors mounted on the tips of the front and the rear wing. The main goal of the presented research was to find the aerodynamic impact of both pairs of tilt-rotors on aerodynamic coefficients of the aircraft. Moreover, the rotors impact on the static stability of the aircraft was investigated too.

Design/methodology/approach

The CFD analysis was made for the complete aircraft in the tandem wing configuration. The computation was performed for the model of aircraft which was equipped with the four sub-models of the front and rear rotors. They were modeled as the actuator discs. This method allows for computing the aerodynamic impact of rotating components on the aircraft body. All aerodynamic analysis was made by the MGAERO software. The numerical code of the software was based on the Euler flow model. The used numerical method allows for the quick computation of very complex model of aircraft with a satisfied accuracy.

Findings

The result obtained by computation includes the aerodynamic coefficients which described the impact of the tilt rotors on the aircraft aerodynamic. The influence of the angle of attack, sideslip angle and the change of rotor tilt angle was investigated. Evaluation of the influence was made by the stability margin analysis and the selected stability derivatives computation.

Practical implications

Presented results could be very useful in the computation of dynamic stability of unconventional aircraft. Moreover, results could be helpful during designing the aircraft in the tandem wing configuration.

Originality/value

This paper presents the aerodynamic analysis of the unconventional configuration of the aircraft which combines the tandem wing feature with the tilt-rotor advantages. The impact of disturbance generated by the front and rear rotors on the flow around the aircraft was investigated. Moreover, the impact of rotors configuration on the aircraft static stability was found too.
Development of a testing methodology for high-altitude propeller
Authors: Jiao Jun , Song Bifeng , Li Yubin , Zhang Yugang , Xu Jianhua
Published: October 2018

Purpose

The purpose of this paper is to develop a propeller performance measurement method for high-altitude platforms by analyzing of the propeller aerodynamic characteristics and application of a mobile testing system.

Design/methodology/approach

An experimental approach is adopted for this study. Considering the aerodynamic characteristics of the high-altitude propeller, the similitude of the scaled propeller model in the experiment is analyzed and determined. Then, the experimental method and procedure to obtain the propeller’s performance under different altitudes are presented, and the structure of hardware and software and the key techniques of the testing system are introduced in detail.

Findings

The applicability and effectiveness of the testing system is verified through comparison between experimental and numerical results. In addition, the performance of the 6.8-m propeller for a high-altitude airship is tested, which proves that the high-altitude propeller can meet the requirements of the propulsion system.

Practical implications

The testing methodology and the mobile testing system could be applied to aerodynamic performance evaluation of the high-altitude propellers under different altitudes.

Originality/value

This testing approach exhibits significant time and cost benefits over many other experimental methods to obtain the performance of the high-altitude propellers, which is important in the preliminary design of the propulsion system for high-altitude platforms.
Combustion characteristics of a two-stroke spark ignition UAV engine fuelled with gasoline and kerosene (RP-3)
Authors: Liu Rui , Su Xiaoping , Miao Xiaodong , Yang Guang , Dong Xuefei , Liang Yongsheng , Huang Taiqi
Published: October 2018

Purpose

The purpose of this paper is to compare the combustion characteristics, including the combustion pressure, heat release rate (HRR), coefficient of variation (COV) of indicated mean effective pressure (IMEP), flame development period and combustion duration, of aviation kerosene fuel, namely, rocket propellant 3 (RP-3), and gasoline on a two-stoke spark ignition engine.

Design/methodology/approach

This paper is an experimental investigation using a bench test to reflect the combustion performance of two-stroke spark ignition unmanned aerial vehicle (UAV) engine on gasoline and RP-3 fuel.

Findings

Under low load conditions, the combustion performance and HRR of burning RP-3 fuel were shown to be worse than those of gasoline. Under high load conditions, the average IMEP and the COV of IMEP of burning RP-3 fuel were close to those of gasoline. The difference in the flame development period between gasoline and RP-3 fuel was similar.

Practical implications

Gasoline fuel has a low flash point, high-saturated vapour pressure and relatively high volatility and is a potential hazard near a naked flame at room temperature, which can create significant security risks for its storage, transport and use. Adopting a low volatility single RP-3 fuel of covering all vehicles and equipment to minimize the number of different devices with the use of a various fuels and improve the application safeties.

Originality/value

Most two-stroke spark ignition UAV engines continue to combust gasoline. A kerosene-based fuel operation can be applied to achieve a single-fuel policy.
A vision-based method for supporting autonomous aircraft landing
Authors: Oszust Mariusz , Kapuscinski Tomasz , Warchol Dawid , Wysocki Marian , Rogalski Tomasz , Pieniazek Jacek , Kopecki Grzegorz Henryk , Ciecinski Piotr , Rzucidlo Pawel
Published: October 2018

Purpose

This paper aims to present a vision-based method for determination of the position of a fixed-wing aircraft that is approaching a runway.

Design methodology/approach

The method determines the location of an aircraft based on positions of precision approach path indicator lights and approach light system with sequenced flashing lights in the image captured by an on-board camera.

Findings

As the relation of the lighting systems to the touchdown area on the considered runway is known in advance, the detected lights, seen as glowing lines or highlighted areas, in the image can be mapped onto the real-world coordinates and then used to estimate the position of the aircraft. Furthermore, the colours of lights are detected and can be used as auxiliary information.

Practical implications

The presented method can be considered as a potential source of flight data for autonomous approach and for augmentation of manual approach.

Originality/value

In this paper, a feasibility study of this concept is presented and primarily validated.
The diversity of monographs: changing landscape of book evaluation in Poland
Authors: Kulczycki Emanuel
Published: October 2018

Purpose

The purpose of this paper is to determine the characteristic patterns of monographs in the humanities, social sciences and hard sciences published by Polish scholars. The study provides a comprehensive overview of the Polish book evaluation system to explain how monographs are assessed and illustrate how changes in the definitions of the types of scholarly book publications influence publication patterns.

Design/methodology/approach

This paper analyses bibliographic records of 42,307 monographs published by Polish scholars in the humanities and science fields from 2009 to 2016. Through a bibliometric analysis, the paper investigates the characteristic patterns of the monographs, including authorship, publication language and length, across three fields.

Findings

The present study demonstrates that changes in the definitions of scholarly book publications in Poland have significantly influenced the characteristic patterns of monographs. The analysis of the characteristic patterns across three fields reveals that the monographs are different in terms of all characteristics. In the entire period, 85.3 percent monographs were written in Polish, 10.1 percent in English, 1.4 percent in German, 1.1 percent in Russian and 2.1 percent in 39 other languages. The most significant changes are observed in authorship patterns.

Originality/value

This work offers empirical findings on the characteristic patterns of monographs in the humanities, social sciences and hard sciences from a non-English speaking country. It discusses a unique model of book assessment and shows certain consequences of various overly formalized procedures of evaluation. Thus, the study identifies the major challenges and implications of using highly formalized procedures for book evaluation.
Mixed language queries in online searches
Authors: Fu Hengyi
Published: October 2018

Purpose

With the increasing number of online multilingual resources, cross-language information retrieval (CLIR) has drawn much attention from the information retrieval (IR) research community. However, few studies have examined how and why multilingual searchers seek information in two or more languages, specifically how they switch and mix language in queries to get satisfying results. The purpose of this paper is to focus on Chinese–English bilinguals’ intra-sentential code-switching behaviors in online searches. The scenarios and reasons of code-switching, factors that may affect code-switching, the patterns of mixed language query formulation and reformulation and how current IR systems and other search tools can facilitate such information needs were examined.

Design/methodology/approach

In-depth semi-structured interviews were used as the research method. In total, 30 participants were recruited based on their English proficiency, location and profession, using a purposive sampling method.

Findings

Four scenarios and four reasons for using Chinese–English mixed language queries to cover information needs were identified, and results suggest that linguistic and cultural/social factors are of equivalent importance in code-switching behaviors. English terms and Chinese terms in queries play different roles in searches, and mixed language queries are irreplaceable by either single language queries or other search facilitating features. Findings also suggest current search engines and tools need greater emphasis in the user interface and more user education is required.

Originality/value

This study presents a qualitative analysis of bilinguals’ code-switching behaviors in online searches. Findings are expected to advance the theoretical understanding of bilingual users’ search strategies and interactions with IR systems, and provide insights for designing more effective IR systems and tools to discover multilingual online resources, including cross-language controlled vocabularies, personalized CLIR tools and mixed language query assistants.
Website removal from search engines due to copyright violation
Authors: Strzelecki Artur
Published: October 2018

Purpose

The purpose of this paper is to clarify how many removal requests are made, how often, and who makes these requests, as well as which websites are reported to search engines so they can be removed from the search results.

Design/methodology/approach

Undertakes a deep analysis of more than 3.2bn removed pages from Google’s search results requested by reporting organizations from 2011 to 2018 and over 460m removed pages from Bing’s search results requested by reporting organizations from 2015 to 2017. The paper focuses on pages that belong to the .pl country coded top-level domain (ccTLD).

Findings

Although the number of requests to remove data from search results has been growing year on year, fewer URLs have been reported in recent years. Some of the requests are, however, unjustified and are rejected by teams representing the search engines. In terms of reporting copyright violations, one company in particular stands out (AudioLock.Net), accounting for 28.1 percent of all reports sent to Google (the top ten companies combined were responsible for 61.3 percent of the total number of reports).

Research limitations/implications

As not every request can be published, the study is based only what is publicly available. Also, the data assigned to Poland is only based on the ccTLD domain name (.pl); other domain extensions for Polish internet users were not considered.

Originality/value

This is first global analysis of data from transparency reports published by search engine companies as prior research has been based on specific notices.
The learnability of the dimensional view of data and what to do with it
Authors: Vujošević Dušan , Kovačević Ivana , Vujošević-Janičić Milena
Published: October 2018

Purpose

The purpose of this paper is to examine the usability of the dimensional view of data in the context of its presumed learnability.

Design/methodology/approach

In total, 303 participants were asked to solve 12 analytical problems in an experiment using the dimensional view of data for half of the problems and an operational view of data for the other half. Inferential statistics and structural equation modeling were performed with participants’ objective results and affective reactions.

Findings

Showing that the order of exposure to the two views of data impacts the overall usability of ad hoc querying, the study provided evidence for the learnability potential of the dimensional view of data. Furthermore, the study showed that affective reactions to the different views of data follow objective usability parameters in a way that can be explained using models from affective computing research.

Practical implications

The paper proposes a list of guidelines for use of the dimensional view of data in business analytics.

Originality/value

This study is the first to confirm the learnability of the dimensional view of data and the first to take a deeper look at affective reactions to an ad hoc business analytics solution. Also, it is one of few studies that examined the usability of different views of data directly on these views, rather than using paper representations of data models.
Port wine value chain: from the Douro Valley to Oporto Cellars
Authors: Ferreira João Pedro , Ramos Pedro Nogueira , Cruz Luís , Barata Eduardo , Lahr Michael
Published: October 2018

Purpose

The purpose of this paper is to offer an insight into the fundamental changes taking place in Port wine production value chains. Specifically, the authors examine two distinct production regimes: when Port is aged and sold in the Greater Oporto and, alternatively, when it is produced, aged and sold in Douro.

Design/methodology/approach

The authors apply a tri-regional input–output model (Douro, Greater Oporto and rest of the country) for Portugal’s economy. This framework comprises a significant level of detail, with 431 products and 136 industries, the corresponding supply and demand for the products, by industry (for intermediate consumption) and final demand.

Findings

This study shows that the two regimes generate noteworthy, but quite heterogeneous, regional impacts. In both cases, the distribution of value added generates international and interregional trade flows. Moreover, the study reveals a greater capacity to capture national value added by getting the supply chain more intensive in localised services and by using state-of-the-art production techniques.

Originality/value

Using detailed regional data, the authors use disaggregated information, both for industries as well for territories, overcoming a common limitation in similar works that are grounded in international databases. Additionally, the approach integrates the trade interactions among industries and regions, which proves essential to uncovering spillovers resulting from the (direct and indirect) use of inputs from other regions and other countries.
Linked models and theories: a tool for school nutrition policies deployment
Authors: Hamadeh Sima , Marquis Marie
Published: October 2018

Purpose

The purpose of this paper is to explore the pertinence of using an integrated conceptual framework based on several theories and models to guide interviews with adults and youth as a prelude to school nutrition policy (SNP) deployment.

Design/methodology/approach

Appropriate socio-behavioral and communication theories and models within a social marketing approach were used to build the integrated conceptual framework of this study. The target population consists of 115 multidisciplinary key stakeholders in Lebanon. Directed and semi-structured individual interviews and focus groups were conducted by using questionnaires associated with the variables of the framework. Collected data have been submitted to a thematic qualitative analysis.

Findings

Combining theories and models increases the potential for understanding the broader determinants of SNP deployment. It is important to choose a holistic theoretical perspective: to study key stakeholders’ perceptions of the facilitators and barriers of SNP development and implementation, to emphasize the active participation of communities and to guide the work of policy and decision makers.

Practical implications

This research offers perspectives on determinants factors envisaged in the deployment of SNP that help key stakeholders in their promotion and communication practices.

Social implications

For public policy makers, this research suggests a need to address communities perceptions’ of an eventual SNP deployment.

Originality/value

The comprehensive integrated conceptual framework proposed in this study amalgamates several variables involved in the process of health promotion under various categories to facilitate SNP deployment.