bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Non-Metallic Inclusions on the Fracture-Toughness Properties on the Longitudinal Welding of an API 5L Steel Pipeline
Authors: Angeles-Herrera D. , Albiter-Hernández A. , Cuamatzi-Meléndez R. , Morales-Ramirez A. de J. 
Published: February 2016

Abstract
In previous works, it was demonstrated that the average fracture-toughness values were higher in the circumferential-longitudinal direction (CL) than in the circumferential-radial direction (CR) on the longitudinal submerged arc welding (SAW) in API 5L pipeline steel. Nevertheless, such differences in fracture-toughness values were attributed to the density distribution of microstructural phases and porosity, but the effect of non-metallic inclusions on this fracture property was not considered; therefore, the present work analyzed the effect of non-metallic inclusions on the fracture-toughness values by fractographic and electron diffraction scattered analyses. The results showed the presence of titanium (Ti), calcium (Ca), and aluminum (Al) constituents in the non-metallic inclusions for the CR direction of the pipeline. These elements tended to form compounds that promoted brittle-fracture by cleavage, decreasing the toughness properties of the weld. For the CL direction analysis, the elements presented on the non-metallic inclusions were manganese (Mn), silicon (Si), and sulfur (S), which promoted the nucleation and coalescence of cavities, all of which were typical for ductile fracture. Calculations on the KIC showed that the non-metallic inclusions with elements of Ti, Ca, and Al contributed to lower KIC values on the CR direction under analysis.
Ruggedness Study of Dynamic Modulus Testing of Asphalt Concrete in Indirect Tension Mode
Authors: Norouzi Amirhossein , Kim Y. Richard 
Published: February 2016

Abstract
The modulus is one of the primary asphalt mixture properties used for the mechanistic performance prediction of asphalt pavements. Dynamic modulus testing is a common method of measuring mixture modulus as a function of loading frequencies and temperatures. This paper presented the results of a ruggedness study of dynamic modulus testing in indirect tension mode to evaluate the factors that were most likely to affect the final results. Specimen thickness, air void content, gauge length, test temperature, and horizontal strain level, which are the critical factors that affect the dynamic modulus of asphalt concrete, were selected for the ruggedness analysis. Two different asphalt mixtures with the participation of two laboratories were used in the study. Based on the selected values for the different variables, air void content was found to be the significant factor that affected dynamic modulus testing and dynamic modulus values. The other factors did not appear to have a major impact on the test results; however, reasonable tolerances were obtained for the other parameters investigated in this paper.
Effect of the Welan Gum Biopolymer on Rheological Properties and Storage Stability of Bitumens
Authors: Tu Liang-Liang , Wu Shao-Peng , Liu Gang , Zhou Xin-Xing , Ma Shan-Kui 
Published: February 2016

Abstract
The welan gum, as a biopolymer, is commonly used in the cement mortar to control bleeding and prevent segregation due to its long-chain molecules. This paper studied the effect of welan gum on the rheological behavior of base bitumen and the storage stability of bitumen modified with montmorillonite (MMT). Four contents (0.2, 0.5, 1, and 3 % by weight) of welan gum were used to mix with base bitumen at a suitable temperature of 160°C. The dynamic shear rheometer was adopted to evaluate the viscosity as the function of shear rate. The results indicated that the welan gum, especially with 0.5 % by weight, notably reinforced the shear-thinning behavior of base bitumen at 135 and 160°C. It implied that the welan gum can improve the drainage resistance of asphalt mixture during storage and transportation. Based on this result, the storage stability of MMT modified bitumens with and without 0.5 % welan gum by weight was characterized by the difference in the complex modulus (G*) and the phase angle (δ) of bitumen sampled from the top and bottom layer of the storage tube. The result indicated that the welan gum can apparently improve the storage stability of the MMT modified bitumen.
Comparative Study of Methods to Measure the Density of Cementitious Powders
Authors: Helsel Michelle A. , Ferraris Chiara F. , Bentz Dale 
Published: February 2016

Abstract
The accurate measurement of the density of hydraulic cement plays an essential role in the determination of concrete mixture proportions. As more supplementary cementitious materials (SCM), such as fly ash and slag, or cement replacement materials, such as limestone and calcium carbonate, are used in blended cements, knowledge of the density of each powder or of the blended cement would allow a more accurate calculation of the proportions of a concrete mixture by volume instead of by mass. The current ASTM standard for measuring cement density is ASTM C188-14 “Test Method for Density of Hydraulic Cements,” which utilizes a liquid displacement method to measure the volume of the cement. This paper examined advantageous modifications of the current ASTM test by alcohol substitutions for kerosene. In addition, a gas (helium) pycnometry method was evaluated as a possible alternative to the current standard. The described techniques were compared to determine the most precise and reproducible method for measuring the density of hydraulic cements and other powders.
Prioritization-Optimization Process Algorithm to Manage Pavement Networks During the Non-Availability of Historical Data
Authors: Kitaha A. , Biligiri K. Prapoorna 
Published: February 2016

Abstract
A common practice followed to rate the pavement surface condition is to use the ASTM D5340-12 procedure and estimate the pavement condition index (PCI) that helps prioritize maintenance needs and assists developing a pavement management system (PMS). However, ASTM-PCI that is dependent on time-based evaluation may not be suitable where there is a lack of historical records and it is being undertaken for the first time. To estimate a pavement's current PCI during the non-availability of historical data and establish a PMS incorporated with prioritized maintenance and optimized budget, a rational engineering criteria (EC) based methodological approach is required that is as robust as ASTM D5340-12. Thus, the objective of this study was to develop a rational EC-based prioritization-optimization process PMS (POPMS) algorithm for a network that prioritizes maintenance strategies for identified pavement distresses and hence optimizes maintenance costs depending on budgetary allocations. An EC-based POPMS algorithm was based on a network length of 100.55 km, which followed prioritization-optimization process for single to multi-year programs. EC-PCI of pavement sections were estimated on the basis of segmented maintenance strategies including preventive and routine maintenance and reconstruction. EC-PCI was found to be rational since three distinct threshold zones were considered that could directly assign pavement maintenance strategies, which was straightforward and circularly referenced. Overall, POPMS algorithm facilitates practitioners to modify the threshold EC-based parameters that will estimate an optimal single/multiyear budget for maintenance as per the newly set threshold level, thus creating a whole new promising approach in the areas of roadway network level maintenance programs.
Thermally Activated Healing of Fatigue Damage in Asphalt Binders
Authors: Liu Quantao , Tang Jin , He Liang 
Published: February 2016

Abstract
Asphalt binder is a self-healing material and it has a potential to heal faster with increased temperatures. This paper investigates the thermally activated healing of fatigue damage in three asphalt binders, trying to answer the question: At what temperatures do asphalt binders heal? After fatiguing the sample, a heating treatment was applied and the sample was fatigued for the second time. The recovered fatigue life and the recovered accumulated dissipated energy are used to quantify the thermally activated healing rates of asphalt binders. It is found that these two healing indexes coincide well with each other in different healing conditions. Base asphalt binders can heal the fatigue damage completely after heating for 20 min at the softening-point temperatures. Styrene–butadiene–styrene (SBS)-modified asphalt binder can achieve full healing at a temperature 20°C below its softening point, where the elastic recovery of the SBS chain segment may play an important role in healing. It is also found that healing of fatigue damage in asphalt binder is highly strain dependent: the healing ratio is higher at high strain amplitude. It proved that thermally activated healing can be repeated when damage returns in asphalt binder. It is concluded that thermally activated healing of fatigue damage is definitely useful to increase the fatigue life of asphalt binders and different asphalt binders should be heated to certain temperatures related to their specific softening points.
Metabotropic Glutamate Receptors Induce a Form of LTP Controlled by Translation and Arc Signaling in the Hippocampus
Authors: Wang Hui , Ardiles Alvaro O. , Yang Sunggu , Tran Trinh , Posada-Duque Rafael , Valdivia Gonzalo , Baek Min , Chuang Yang-An , Palacios Adrian G. , Gallagher Michela , Worley Paul , Kirkwood Alfredo 
Published: February 2016

Activity-dependent bidirectional modifications of excitatory synaptic strength are essential for learning and storage on new memories. Research on bidirectional synaptic plasticity has largely focused on long-term potentiation (LTP) and long-term depression (LTD) mechanisms that rely on the activation of NMDA receptors. In principle, metabotropic glutamate receptors (mGluRs) are also suitable to convert synaptic activity into intracellular signals for synaptic modification. Indeed, dysfunction of a form of LTD that depends on Type I mGluRs (mGluR-LTD), but not NMDARs, has been implicated in learning deficits in aging and mouse models of several neurological conditions, including Fragile X syndrome and Alzheimer's disease. To determine whether mGluR activation can also induce LTP in the absence of NMDAR activation, we examined in hippocampal slices from rats and mice, an NMDAR-independent form of LTP previously characterized as dependent on voltage-gated Ca2+channels. We found that this form of LTP requires activation of Type I mGluRs and, like mGluR-LTD but unlike NMDAR-dependent plasticity, depends crucially on protein synthesis controlled by fragile X mental retardation protein and on Arc signaling. Based on these observations, we propose the coexistence of two distinct activity-dependent systems of bidirectional synaptic plasticity: one that is based on the activity of NMDARs and the other one based on the activation of mGluRs.SIGNIFICANCE STATEMENTBidirectional changes of synaptic strength are crucial for the encoding of new memories. Currently, the only activity-dependent mechanism known to support such bidirectional changes are long-term potentiation (LTP) and long-term depression (LTD) forms that relay on the activation of NMDA receptors. Metabotropic glutamate receptors (mGluRs) are, in principle, also suitable to trigger bidirectional synaptic modifications. However, only the mGluR-dependent form of LTD has been characterized. Here we report that an NMDAR-independent form of LTP, initially characterized as dependent on voltage-gated Ca2+channels, also requires the activation of mGluRs. These finding suggest the coexistence of two distinct activity-dependent systems of bidirectional synaptic plasticity: one that is based on the activity of NMDARs and the other one based on the activation of mGluRs.
Left Superior Temporal Gyrus Is Coupled to Attended Speech in a Cocktail-Party Auditory Scene
Authors: Vander Ghinst Marc , Bourguignon Mathieu , Op de Beeck Marc , Wens Vincent , Marty Brice , Hassid Sergio , Choufani Georges , Jousmäki Veikko , Hari Riitta , Van Bogaert Patrick , Goldman Serge , De Tiège Xavier 
Published: February 2016

Using a continuous listening task, we evaluated the coupling between the listener's cortical activity and the temporal envelopes of different sounds in a multitalker auditory scene using magnetoencephalography and corticovocal coherence analysis. Neuromagnetic signals were recorded from 20 right-handed healthy adult humans who listened to five different recorded stories (attended speech streams), one without any multitalker background (No noise) and four mixed with a “cocktail party” multitalker background noise at four signal-to-noise ratios (5, 0, −5, and −10 dB) to produce speech-in-noise mixtures, here referred to as Global scene. Coherence analysis revealed that the modulations of the attended speech stream, presented without multitalker background, were coupled at ∼0.5 Hz to the activity of both superior temporal gyri, whereas the modulations at 4–8 Hz were coupled to the activity of the right supratemporal auditory cortex. In cocktail party conditions, with the multitalker background noise, the coupling was at both frequencies stronger for the attended speech stream than for the unattended Multitalker background. The coupling strengths decreased as the Multitalker background increased. During the cocktail party conditions, the ∼0.5 Hz coupling became left-hemisphere dominant, compared with bilateral coupling without the multitalker background, whereas the 4–8 Hz coupling remained right-hemisphere lateralized in both conditions. The brain activity was not coupled to the multitalker background or to its individual talkers. The results highlight the key role of listener's left superior temporal gyri in extracting the slow ∼0.5 Hz modulations, likely reflecting the attended speech stream within a multitalker auditory scene.SIGNIFICANCE STATEMENTWhen people listen to one person in a “cocktail party,” their auditory cortex mainly follows the attended speech stream rather than the entire auditory scene. However, how the brain extracts the attended speech stream from the whole auditory scene and how increasing background noise corrupts this process is still debated. In this magnetoencephalography study, subjects had to attend a speech stream with or without multitalker background noise. Results argue for frequency-dependent cortical tracking mechanisms for the attended speech stream. The left superior temporal gyrus tracked the ∼0.5 Hz modulations of the attended speech stream only when the speech was embedded in multitalker background, whereas the right supratemporal auditory cortex tracked 4–8 Hz modulations during both noiseless and cocktail-party conditions.
Blockade of Astrocytic Calcineurin/NFAT Signaling Helps to Normalize Hippocampal Synaptic Function and Plasticity in a Rat Model of Traumatic Brain Injury
Authors: Furman Jennifer L. , Sompol Pradoldej , Kraner Susan D. , Pleiss Melanie M. , Putman Esther J. , Dunkerson Jacob , Mohmmad Abdul Hafiz , Roberts Kelly N. , Scheff Stephen W. , Norris Christopher M. 
Published: February 2016

Increasing evidence suggests that the calcineurin (CN)-dependent transcription factor NFAT (Nuclear Factor of Activated T cells) mediates deleterious effects of astrocytes in progressive neurodegenerative conditions. However, the impact of astrocytic CN/NFAT signaling on neural function/recovery after acute injury has not been investigated extensively. Using a controlled cortical impact (CCI) procedure in rats, we show that traumatic brain injury is associated with an increase in the activities of NFATs 1 and 4 in the hippocampus at 7 d after injury. NFAT4, but not NFAT1, exhibited extensive labeling in astrocytes and was found throughout the axon/dendrite layers of CA1 and the dentate gyrus. Blockade of the astrocytic CN/NFAT pathway in rats using adeno-associated virus (AAV) vectors expressing the astrocyte-specific promoter Gfa2 and the NFAT-inhibitory peptide VIVIT prevented the injury-related loss of basal CA1 synaptic strength and key synaptic proteins and reduced the susceptibility to induction of long-term depression. In conjunction with these seemingly beneficial effects, VIVIT treatment elicited a marked increase in the expression of the prosynaptogenic factor SPARCL1 (hevin), especially in hippocampal tissue ipsilateral to the CCI injury. However, in contrast to previous work on Alzheimer's mouse models, AAV-Gfa2-VIVIT had no effects on the levels of GFAP and Iba1, suggesting that synaptic benefits of VIVIT were not attributable to a reduction in glial activation per se. Together, the results implicate the astrocytic CN/NFAT4 pathway as a key mechanism for disrupting synaptic remodeling and homeostasis in the hippocampus after acute injury.SIGNIFICANCE STATEMENTSimilar to microglia, astrocytes become strongly “activated” with neural damage and exhibit numerous morphologic/biochemical changes, including an increase in the expression/activity of the protein phosphatase calcineurin. Using adeno-associated virus (AAV) to inhibit the calcineurin-dependent activation of the transcription factor NFAT (Nuclear Factor of Activated T cells) selectively, we have shown that activated astrocytes contribute to neural dysfunction in animal models characterized by progressive/chronic neuropathology. Here, we show that the suppression of astrocytic calcineurin/NFATs helps to protect synaptic function and plasticity in an animal model in which pathology arises from a single traumatic brain injury. The findings suggest that at least some astrocyte functions impair recovery after trauma and may provide druggable targets for treating victims of acute nervous system injury.
On the Structure of Neuronal Population Activity under Fluctuations in Attentional State
Authors: Ecker Alexander S. , Denfield George H. , Bethge Matthias , Tolias Andreas S. 
Published: February 2016

Attention is commonly thought to improve behavioral performance by increasing response gain and suppressing shared variability in neuronal populations. However, both the focus and the strength of attention are likely to vary from one experimental trial to the next, thereby inducing response variability unknown to the experimenter. Here we study analytically how fluctuations in attentional state affect the structure of population responses in a simple model of spatial and feature attention. In our model, attention acts on the neural response exclusively by modulating each neuron's gain. Neurons are conditionally independent given the stimulus and the attentional gain, and correlated activity arises only from trial-to-trial fluctuations of the attentional state, which are unknown to the experimenter. We find that this simple model can readily explain many aspects of neural response modulation under attention, such as increased response gain, reduced individual and shared variability, increased correlations with firing rates, limited range correlations, and differential correlations. We therefore suggest that attention may act primarily by increasing response gain of individual neurons without affecting their correlation structure. The experimentally observed reduction in correlations may instead result from reduced variability of the attentional gain when a stimulus is attended. Moreover, we show that attentional gain fluctuations, even if unknown to a downstream readout, do not impair the readout accuracy despite inducing limited-range correlations, whereas fluctuations of the attended feature can in principle limit behavioral performance.SIGNIFICANCE STATEMENTCovert attention is one of the most widely studied examples of top-down modulation of neural activity in the visual system. Recent studies argue that attention improves behavioral performance by shaping of the noise distribution to suppress shared variability rather than by increasing response gain. Our work shows, however, that latent, trial-to-trial fluctuations of the focus and strength of attention lead to shared variability that is highly consistent with known experimental observations. Interestingly, fluctuations in the strength of attention do not affect coding performance. As a consequence, the experimentally observed changes in response variability may not be a mechanism of attention, but rather a side effect of attentional allocation strategies in different behavioral contexts.
The Effect of Early Visual Deprivation on the Neural Bases of Auditory Processing
Authors: Guerreiro Maria J. S. , Putzar Lisa , Röder Brigitte 
Published: February 2016

Transient congenital visual deprivation affects visual and multisensory processing. In contrast, the extent to which it affects auditory processing has not been investigated systematically. Research in permanently blind individuals has revealed brain reorganization during auditory processing, involving both intramodal and crossmodal plasticity. The present study investigated the effect of transient congenital visual deprivation on the neural bases of auditory processing in humans. Cataract-reversal individuals and normally sighted controls performed a speech-in-noise task while undergoing functional magnetic resonance imaging. Although there were no behavioral group differences, groups differed in auditory cortical responses: in the normally sighted group, auditory cortex activation increased with increasing noise level, whereas in the cataract-reversal group, no activation difference was observed across noise levels. An auditory activation of visual cortex was not observed at the group level in cataract-reversal individuals. The present data suggest prevailing auditory processing advantages after transient congenital visual deprivation, even many years after sight restoration.SIGNIFICANCE STATEMENTThe present study demonstrates that people whose sight was restored after a transient period of congenital blindness show more efficient cortical processing of auditory stimuli (here speech), similarly to what has been observed in congenitally permanently blind individuals. These results underscore the importance of early sensory experience in permanently shaping brain function.