bluuebunny/crossref_metadata_2025_split huggingface dataset:
Matrix and discrepancy view of generalized random and quasirandom graphs
Authors: Bolla Marianna , Elbanna Ahmed 
Published: January 2016

Abstract
We will discuss how graph based matrices are capable to find classification of the graph vertices with small within- and between-cluster discrepancies. The structural eigenvalues together with the corresponding spectral subspaces of the normalized modularity matrix are used to find a block-structure in the graph. The notions are extended to rectangular arrays of nonnegative entries and to directed graphs. We also investigate relations between spectral properties, multiway discrepancies, and degree distribution of generalized random graphs. These properties are regarded as generalized quasirandom properties, and we conjecture and partly prove that they are also equivalent for certain deterministic graph sequences, irrespective of stochastic models.
Thrust Performance Evaluation of a Turbofan Engine Based on Exergetic Approach and Thrust Management in Aircraft
Authors: Yalcin Enver 
Published: January 2016

AbstractThe environmental parameters such as temperature and air pressure which are changing depending on altitudes are effective on thrust and fuel consumption of aircraft engines. In flights with long routes, thrust management function in airplane information system has a structure that ensures altitude and performance management. This study focused on thrust changes throughout all flight were examined by taking into consideration their energy and exergy performances for fuel consumption of an aircraft engine used in flight with long route were taken as reference. The energetic and exergetic performance evaluations were made under the various altitude conditions. The thrust changes for different altitude conditions were obtained to be at 86.53 % in descending direction and at 142.58 % in ascending direction while the energy and exergy efficiency changes for the referenced engine were found to be at 80.77 % and 84.45 %, respectively. The results revealed here can be helpful to manage thrust and reduce fuel consumption, but engine performance will be in accordance with operation requirements.
Unsteady Mixed Bioconvection Flow of a Nanofluid Between Two Contracting or Expanding Rotating Discs
Authors: Li Jiao Jiao , Xu Hang , Raees Ammarah , Zhao Qing Kai 
Published: January 2016

Abstract
An investigation is made for a three-dimensional unsteady mixed nano-bioconvection flow between two contracting or expanding rotating discs. The passively controlled nanofluid model in which Brownian diffusion and thermophoresis are considered as the two dominant factors for nanoparticle/base-fluid slip mechanisms is introduced for description of this flow problem. A novel similarity transformation is introduced so that the governing equations embodying the conservation of total mass, momentum, thermal energy, nanoparticle volume fraction, and microorganisms are reduced to a set of five fully coupled ordinary differential equations. Exact solutions are then obtained analytically for this complex nonlinear system. Besides, the influences of various physical parameters on distributions of velocity, temperature, nanoparticle volume fraction, and the density of motile microorganisms, along with the local Nusselt number and the local wall motile microorganisms flux, are presented and discussed. It is expected that this study can provide a theoretical base for understanding the transport mechanisms of unsteady bioconvection in nanofluids.
Alkaloid profiles and acetylcholinesterase inhibitory activities of Fumaria species from Bulgaria
Authors: Vrancheva Radka Z. , Ivanov Ivan G. , Aneva Ina Y. , Dincheva Ivayla N. , Badjakov Ilian K. , Pavlov Atanas I. 
Published: January 2016

Abstract
GC-MS analysis of alkaloid profiles of five Fumaria species, naturally grown in Bulgaria (F. officinalis, F. thuretii, F. kralikii, F. rostellata and F. schrammii) and analysis of acetylcholinesterase inhibitory activity of alkaloid extracts were performed. Fourteen isoquinoline alkaloids were identified, with the principle ones being protopine, cryptopine, sinactine, parfumine, fumariline, fumarophycine, and fumaritine. Protopine contents, defined by HPLC analysis varied between 210.6 ± 8.8 μg/g DW (F. schrammii) and 334.5 ± 7.1 μg/g DW. (F. rostellata). While all of the investigated alkaloid extracts significantly inhibited acetylcholinesterase activity, the F. kralikii demonstrated the highest level of inhibition (IC50 0.13 ± 0.01 mg extract/mL).
Solid State Structure Prediction Through DFT Calculations and 13C NMR Measurements: Case Study of Spiro-2,4-dithiohydantoins
Authors: Antonov Vladislav , Nedyalkova Miroslava , Tzvetkova Pavleta , Ahmedova Anife 
Published: January 2016

Abstract
We present a DFT approach for precise estimation of the intermolecular
effects on the experimental and calculated 13C NMR shifts
for a series of 5-spiro-2,4-dithiohydantoins
(1–5), both in solid state and in solution. It has
been found that the used B3LYP/6-31+ G** method gives very
good agreement with the experimental structural and the NMR
parameters, provided the intermolecular hydrogen bonds are properly
considered. For correct description of the experimental NMR shifts in
solid state we have initially used the isolated-molecule and the
cluster approaches for GIAO calculations of the NMR shifts, followed
by periodic boundary condition calculations of the structure and the
nuclear magnetic shielding constants by the GIPAW method implemented
in the Quantum Espresso code. The best agreement with the experimental
solid state data is obtained for the optimized small cluster (a trimer
of molecules) in the calculations using the atom-centered
orbitals. Excellent agreement between the 13C CPMAS NMR
and the GIPAW calculated shift is obtained for fully relaxed bulk
structures of compounds 1–5. This has been used as
a final verification of the proposed solid state structure of compound
5 whose crystal structure is unknown yet.
Assessing Accuracy of Exchange-Correlation Functionals for the Description of Atomic Excited States
Authors: Makowski Marcin , Hanas Martyna 
Published: January 2016

Abstract
The performance of exchange-correlation functionals for the
description of atomic excitations is investigated. A benchmark set of
excited states is constructed and experimental data is compared to
Time-Dependent Density Functional Theory (TDDFT) calculations. The
benchmark results show that for the selected group of functionals good
accuracy may be achieved and the quality of predictions provided is
competitive to computationally more demanding coupled-cluster
approaches. Apart from testing the standard TDDFT approaches, also
the role of self-interaction error plaguing DFT calculations and the
adiabatic approximation to the exchange-correlation kernels is given
some insight.
Intensive Atomization Energy: Re-Thinking a Metric for Electronic Structure Theory Methods
Authors: Perdew John P. , Sun Jianwei , Garza Alejandro J. , Scuseria Gustavo E. 
Published: January 2016

Abstract
The errors in atomization energies (AE) of molecules have long been used to measure the
errors of wavefunction or density functional methods for electronic structure
calculations. In particular, the G3 set of Pople and collaborators (for sp-bonded
molecules from the first rows of the periodic table) has become a standard benchmark for
such methods. But the mean absolute error of AE tends to increase with increasing number
N
at of atoms in a molecule. In fact, AE is an extensive variable, which
diverges as N
at →∞. Here, as did Savin and Johnson 2015, we define an
intensive atomization energy, IAE = AE/N
at or atomization energy per atom, which
tends to the finite cohesive energy (per atom) of a large cluster or solid (N
at →∞). We find that the mean absolute error of the G3 molecular IAE from
accurate density functionals remains close to 1 kcal/mol as the average molecular
size increases. This makes it possible to estimate in advance the magnitude of the error in
AE for a molecule similar to most of those in the G3 set. It also allows us identify the
G3 “outlying molecules”, and to more directly compare the accuracy of a given functional
for different kinds of molecules (such as those containing transition-metal atoms) to that
for G3-type molecules, by removing the otherwise-uncontrolled size factor. Finally, we point
out that the familiar concept of “chemical accuracy” needs to be qualified.
Embodying Others in Immersive Virtual Reality: Electro-Cortical Signatures of Monitoring the Errors in the Actions of an Avatar Seen from a First-Person Perspective
Authors: Pavone Enea Francesco , Tieri Gaetano , Rizza Giulia , Tidoni Emmanuele , Grisoni Luigi , Aglioti Salvatore Maria 
Published: January 2016

Brain monitoring of errors in one's own and other's actions is crucial for a variety of processes, ranging from the fine-tuning of motor skill learning to important social functions, such as reading out and anticipating the intentions of others. Here, we combined immersive virtual reality and EEG recording to explore whether embodying the errors of an avatar by seeing it from a first-person perspective may activate the error monitoring system in the brain of an onlooker. We asked healthy participants to observe, from a first- or third-person perspective, an avatar performing a correct or an incorrect reach-to-grasp movement toward one of two virtual mugs placed on a table. At the end of each trial, participants reported verbally how much they embodied the avatar's arm. Ratings were maximal in first-person perspective, indicating that immersive virtual reality can be a powerful tool to induce embodiment of an artificial agent, even through mere visual perception and in the absence of any cross-modal boosting. Observation of erroneous grasping from a first-person perspective enhanced error-related negativity and medial–frontal theta power in the trials where human onlookers embodied the virtual character, hinting at the tight link between early, automatic coding of error detection and sense of embodiment. Error positivity was similar in 1PP and 3PP, suggesting that conscious coding of errors is similar for self and other. Thus, embodiment plays an important role in activating specific components of the action monitoring system when others' errors are coded as if they are one's own errors.SIGNIFICANCE STATEMENTDetecting errors in other's actions is crucial for social functions, such as reading out and anticipating the intentions of others. Using immersive virtual reality and EEG recording, we explored how the brain of an onlooker reacted to the errors of an avatar seen from a first-person perspective. We found that mere observation of erroneous actions enhances electrocortical markers of error detection in the trials where human onlookers embodied the virtual character. Thus, the cerebral system for action monitoring is maximally activated when others' errors are coded as if they are one's own errors. The results have important implications for understanding how the brain can control the external world and thus creating new brain–computer interfaces.
Decentralized Multisensory Information Integration in Neural Systems
Authors: Zhang Wen-hao , Chen Aihua , Rasch Malte J. , Wu Si 
Published: January 2016

How multiple sensory cues are integrated in neural circuitry remains a challenge. The common hypothesis is that information integration might be accomplished in a dedicated multisensory integration area receiving feedforward inputs from the modalities. However, recent experimental evidence suggests that it is not a single multisensory brain area, but rather many multisensory brain areas that are simultaneously involved in the integration of information. Why many mutually connected areas should be needed for information integration is puzzling. Here, we investigated theoretically how information integration could be achieved in a distributed fashion within a network of interconnected multisensory areas. Using biologically realistic neural network models, we developed a decentralized information integration system that comprises multiple interconnected integration areas. Studying an example of combining visual and vestibular cues to infer heading direction, we show that such a decentralized system is in good agreement with anatomical evidence and experimental observations. In particular, we show that this decentralized system can integrate information optimally. The decentralized system predicts that optimally integrated information should emerge locally from the dynamics of the communication between brain areas and sheds new light on the interpretation of the connectivity between multisensory brain areas.SIGNIFICANCE STATEMENTTo extract information reliably from ambiguous environments, the brain integrates multiple sensory cues, which provide different aspects of information about the same entity of interest. Here, we propose a decentralized architecture for multisensory integration. In such a system, no processor is in the center of the network topology and information integration is achieved in a distributed manner through reciprocally connected local processors. Through studying the inference of heading direction with visual and vestibular cues, we show that the decentralized system can integrate information optimally, with the reciprocal connections between processers determining the extent of cue integration. Our model reproduces known multisensory integration behaviors observed in experiments and sheds new light on our understanding of how information is integrated in the brain.
Normal Molecular Specification and Neurodegenerative Disease-Like Death of Spinal Neurons Lacking the SNARE-Associated Synaptic Protein Munc18-1
Authors: Law Chris , Schaan Profes Marcos , Levesque Martin , Kaltschmidt Julia A. , Verhage Matthijs , Kania Artur 
Published: January 2016

The role of synaptic activity during early formation of neural circuits is a topic of some debate; genetic ablation of neurotransmitter release by deletion of theMunc18-1gene provides an excellent model to answer the question of whether such activity is required for early circuit formation. Previous analysis ofMunc18-1−/−mouse mutants documented their grossly normal nervous system, but its molecular differentiation has not been assessed.Munc18-1deletion in mice also results in widespread neurodegeneration that remains poorly characterized. In this study, we demonstrate that the early stages of spinal motor circuit formation, including motor neuron specification, axon growth and pathfinding, and mRNA expression, are unaffected inMunc18-1−/−mice, demonstrating that synaptic activity is dispensable for early nervous system development. Furthermore, we show that the neurodegeneration caused by Munc18-1 loss is cell autonomous, consistent with apparently normal expression of several neurotrophic factors and normal GDNF signaling. Consistent with cell-autonomous degeneration, we demonstrate defects in the trafficking of the synaptic proteins Syntaxin1a and PSD-95 and the TrkB and DCC receptors inMunc18-1−/−neurons; these defects do not appear to cause ER stress, suggesting other mechanisms for degeneration. Finally, we demonstrate pathological similarities to Alzheimer's disease, such as altered Tau phosphorylation, neurofibrillary tangles, and accumulation of insoluble protein plaques. Together, our results shed new light upon the neurodegeneration observed inMunc18-1−/−mice and argue that this phenomenon shares parallels with neurodegenerative diseases.SIGNIFICANCE STATEMENTIn this work, we demonstrate the absence of a requirement for regulated neurotransmitter release in the assembly of early neuronal circuits by assaying transcriptional identity, axon growth and guidance, and mRNA expression in Munc18-1-null mice. Furthermore, we characterize the neurodegeneration observed inMunc18-1mutants and demonstrate that this cell-autonomous process does not appear to be a result of defects in growth factor signaling or ER stress caused by protein trafficking defects. However, we find the presence of various pathological hallmarks of Alzheimer's disease that suggest parallels between the degeneration in these mutants and neurodegenerative conditions.
Somatosensory Temporal Discrimination Threshold Involves Inhibitory Mechanisms in the Primary Somatosensory Area
Authors: Rocchi Lorenzo , Casula Elias , Tocco Pierluigi , Berardelli Alfredo , Rothwell John 
Published: January 2016

Somatosensory temporal discrimination threshold (STDT) is defined as the shortest time interval necessary for a pair of tactile stimuli to be perceived as separate. Although STDT is altered in several neurological disorders, its neural bases are not entirely clear. We used continuous theta burst stimulation (cTBS) to condition the excitability of the primary somatosensory cortex in healthy humans to examine its possible contribution to STDT. Excitability was assessed using the recovery cycle of the N20 component of somatosensory evoked potentials (SEP) and the area of high-frequency oscillations (HFO). cTBS increased STDT and reduced inhibition in the N20 recovery cycle at an interstimulus interval of 5 ms. It also reduced the amplitude of late HFO. All three effects were correlated. There was no effect of cTBS over the secondary somatosensory cortex on STDT, although it reduced the N120 component of the SEP. STDT is assessed conventionally with a simple ascending method. To increase insight into the effect of cTBS, we measured temporal discrimination with a psychophysical method. cTBS reduced the slope of the discrimination curve, consistent with a reduction of the quality of sensory information caused by an increase in noise. We hypothesize that cTBS reduces the effectiveness of inhibitory interactions normally used to sharpen temporal processing of sensory inputs. This reduction in discriminability of sensory input is equivalent to adding neural noise to the signal.SIGNIFICANCE STATEMENTPrecise timing of sensory information is crucial for nearly every aspect of human perception and behavior. One way to assess the ability to analyze temporal information in the somatosensory domain is to measure the somatosensory temporal discrimination threshold (STDT), defined as the shortest time interval necessary for a pair of tactile stimuli to be perceived as separate. In this study, we found that STDT depends on inhibitory mechanisms within the primary somatosensory area (S1). This finding helps interpret the sensory processing deficits in neurological diseases, such as focal dystonia and Parkinson's disease, and possibly prompts future studies using neurostimulation techniques over S1 for therapeutic purposes in dystonic patients.
Context-Dependent Modulation of GABAAR-Mediated Tonic Currents
Authors: Patel Bijal , Bright Damian P. , Mortensen Martin , Frølund Bente , Smart Trevor G. 
Published: January 2016

Tonic GABA currents mediated by high-affinity extrasynaptic GABAAreceptors, are increasingly recognized as important regulators of cell and neuronal network excitability. Dysfunctional GABAAreceptor signaling that results in modified tonic GABA currents is associated with a number of neurological disorders. Consequently, developing compounds to selectively modulate the activity of extrasynaptic GABAAreceptors underlying tonic inhibition is likely to prove therapeutically useful. Here, we examine the GABAAreceptor subtype selectivity of the weak partial agonist, 5-(4-piperidyl)isoxazol-3-ol (4-PIOL), as a potential mechanism for modulating extrasynaptic GABAAreceptor-mediated tonic currents. By using recombinant GABAAreceptors expressed in HEK293 cells, and native GABAAreceptors of cerebellar granule cells, hippocampal neurons, and thalamic relay neurons, 4-PIOL evidently displayed differential agonist and antagonist-type profiles, depending on the extrasynaptic GABAAreceptor isoforms targeted. For neurons, this resulted in differential modulation of GABA tonic currents, depending on the cell type studied, their respective GABAAreceptor subunit compositions, and critically, on the ambient GABA levels. Unexpectedly, 4-PIOL revealed a significant population of relatively low-affinity γ2 subunit-containing GABAAreceptors in the thalamus, which can contribute to tonic inhibition under specific conditions when GABA levels are raised. Together, these data indicate that partial agonists, such as 4-PIOL, may be useful for modulating GABAAreceptor-mediated tonic currents, but the direction and extent of this modulation is strongly dependent on relative expression levels of different extrasynaptic GABAAreceptor subtypes, and on the ambient GABA levels.SIGNIFICANCE STATEMENTA background level of inhibition (tonic) is important in the brain for controlling neuronal excitability. Increased levels of tonic inhibition are associated with some neurological disorders but there are no specific ligands capable of selectively reducing tonic inhibition. Here we explore the use of a GABA partial agonist as a selective chemical tool in three different brain regions. We discover that the activity of a partial agonist is heavily dependent upon the GABAAreceptor subunit composition underpinning tonic inhibition, and on the ambient levels of GABA in the brain.
Dissociations and Associations between Shape and Category Representations in the Two Visual Pathways
Authors: Bracci Stefania , Op de Beeck Hans 
Published: January 2016

The dorsal and ventral visual pathways represent both visual and conceptual object properties. Yet the relative contribution of these two factors in the representational content of visual areas is unclear. Indeed, research investigating brain category representations rarely dissociate visual and semantic properties of objects. We present a human event-related fMRI study with a two-factorial stimulus set with 54 images that explicitly dissociates shape from category to investigate their independent contribution as well as their interactions through representational similarity analyses. Results reveal a contribution from each dimension in both streams, with a transition from shape to category along the posterior-to-anterior anatomical axis. The nature of category representations differs in the two pathways: ventral areas represent object animacy and dorsal areas represent object action properties. Furthermore, information about shape evolved from low-level pixel-based to high-level perceived shape following a posterior-to-anterior gradient similar to the shape-to-category emergence. To conclude, results show that representations of shape and category independently coexist, but at the same time they are closely related throughout the visual hierarchy.SIGNIFICANCE STATEMENTResearch investigating visual cortex conceptual category representations rarely takes into account visual properties of objects. In this report, we explicitly dissociate shape from category and investigate independent contributions and interactions of these two highly correlated dimensions.