Many neuroimaging studies have shown that the hippocampus participates in a resting‐state network called the default mode network. However, how the hippocampus connects to the default mode network, ...whether the hippocampus connects to other resting‐state networks and how the different hippocampal subfields take part in resting‐state networks remains poorly understood. Here, we examined these issues using the high spatial‐resolution 7T resting‐state fMRI dataset from the Human Connectome Project. We used data‐driven techniques that relied on spatially‐restricted Independent Component Analysis, Dual Regression and linear mixed‐effect group‐analyses based on participant‐specific brain morphology. The results revealed two main activity hotspots inside the hippocampus. The first hotspot was located in an anterior location and was correlated with the somatomotor network. This network was subserved by co‐activity in the CA1, CA3, CA4 and Dentate Gyrus fields. In addition, there was an activity hotspot that extended from middle to posterior locations along the hippocampal long‐axis and correlated with the default mode network. This network reflected activity in the Subiculum, CA4 and Dentate Gyrus fields. These results show how different sections of the hippocampus participate in two known resting‐state networks and how these two resting‐state networks depend on different configurations of hippocampal subfield co‐activity.
Advanced intelligent vehicle control systems have evolved in the last few decades thanks to the use of artificial-intelligence-based techniques, the appearance of new sensors, and the development of ...technology necessary for their implementation ....
The factors controlling the oxidative addition of C−C and C−H bonds in arenes mediated by AlI have been computationally explored by means of Density Functional Theory calculations. To this end, we ...compared the processes involving benzene, naphthalene and anthracene which are promoted by a recently prepared anionic AlI‐carbenoid. It is found that this species exhibits a strong tendency to oxidatively activate C−H bonds over C−C bonds, with the notable exception of benzene, where the C−C bond activation is feasible but only under kinetic control reaction conditions. State‐of‐the‐art computational methods based on the combination of the Activation Strain Model of reactivity and the Energy Decomposition Analysis have been used to rationalize the competition between both bond activation reactions as well as to quantitatively analyze in detail the ultimate factors controlling these transformations.
A C−C or a C−H bond? In this work, the competition between oxidative additions of C−C vs. C−H bonds in different arenes promoted by the AlI‐carbenoid shown in the figure is explored. Whereas larger arenes (naphthalene, anthracene) lead to C−H activation products, the C−C bond is preferred in the process involving benzene. State‐of‐the‐art computational tools are used to quantitatively rationalize these reactivity trends.
The influence of the nature of the acid/base pairs on the reactivity of geminal frustrated Lewis pairs (FLPs) (Me2E‐CH2‐E′Ph2) has been computationally explored within the density functional theory ...framework. To this end, the dihydrogen‐activation reaction, one of the most representative processes in the chemistry of FLPs, has been selected. It is found that the activation barrier of this transformation as well as the geometry of the corresponding transition states strongly depend on the nature of the E/E′ atoms (E=Group 15 element, E′=Group 13 element) in the sense that lower barriers are associated with earlier transition states. Our calculations identify the geminal N/Al FLP as the most active system for the activation of dihydrogen. Moreover, the barrier height can be further reduced by replacing the phenyl group attached to the acidic atom by C6F5 or 3,5‐(CF3)2C6H3 (Fxyl) groups. The physical factors controlling the computed reactivity trends are quantitatively described in detail by means of the activation strain model of reactivity combined with the energy decomposition analysis method.
Activating H2: The influence of the nature of the acid/base pairs on the reactivity of geminal frustrated Lewis pairs (FLPs) (Me2E‐CH2‐E′Ph2; see scheme) is analyzed in detail by means of computational methods. The geminal N/Al FLP is identified as the most active system for the dihydrogen activation reaction.
Knowledge of tire-road friction characteristics is essential for the proper performance of most relevant vehicle active safety systems. Therefore, its determination is necessary to improve the ...effectiveness of these systems and to avoid or reduce the consequences of traffic accidents. For this reason, there is a great deal of literature concerning methods and devices for measuring and modeling tire-road friction. Most of these methods have focused on determining the road friction resistance, taking only road composition and making measurements in wet conditions into account. However, friction forces are also dependent on the tire type, since the contact is established between the tire and the road in real driving conditions. Thus, the type and characteristics of the tire have to be considered in the study of the interaction between the vehicle and the road. The aim of this work is to unify the study of the friction coefficient, taking into consideration the two existing bodies involved in the contact, i.e., the tire and road and the main factors that influence the forces in the contact. To this end, a modification of the Pacejka Magic Formula is proposed to include the effects of the main parameters that influence the contact, such as road composition and its state, tire type, vehicle speed, and slip between the tire and the road. To do so, real tests have been conducted on several roads and with different operating conditions. As a result, a more accurate tire-road friction model has been obtained.
The anthropogenic increase of atmospheric CO.sub.2 concentration (c.sub.a) is impacting carbon (C), water, and nitrogen (N) cycles in grassland and other terrestrial biomes. Plant canopy stomatal ...conductance is a key player in these coupled cycles: it is a physiological control of vegetation water use efficiency (the ratio of C gain by photosynthesis to water loss by transpiration), and it responds to photosynthetic activity, which is influenced by vegetation N status. It is unknown if the c.sub.a-increase and climate change over the last century have already affected canopy stomatal conductance and its links with C and N processes in grassland. Here, we assessed two independent proxies of (growing season-integrating canopy-scale) stomatal conductance changes over the last century: trends of delta.sup.18O in cellulose (delta.sup.18O.sub.cellulose) in archived herbage from a wide range of grassland communities on the Park Grass Experiment at Rothamsted (U.K.) and changes of the ratio of yields to the CO.sub.2 concentration gradient between the atmosphere and the leaf internal gas space (c.sub.a - c.sub.i). The two proxies correlated closely (R.sup.2 = 0.70), in agreement with the hypothesis. In addition, the sensitivity of delta.sup.18O.sub.cellulose changes to estimated stomatal conductance changes agreed broadly with published sensitivities across a range of contemporary field and controlled environment studies, further supporting the utility of delta.sup.18O.sub.cellulose changes for historical reconstruction of stomatal conductance changes at Park Grass. Trends of delta.sup.18O.sub.cellulose differed strongly between plots and indicated much greater reductions of stomatal conductance in grass-rich than dicot-rich communities. Reductions of stomatal conductance were connected with reductions of yield trends, nitrogen acquisition, and nitrogen nutrition index. Although all plots were nitrogen-limited or phosphorus- and nitrogen-co-limited to different degrees, long-term reductions of stomatal conductance were largely independent of fertilizer regimes and soil pH, except for nitrogen fertilizer supply which promoted the abundance of grasses. Our data indicate that some types of temperate grassland may have attained saturation of C sink activity more than one century ago. Increasing N fertilizer supply may not be an effective climate change mitigation strategy in many grasslands, as it promotes the expansion of grasses at the disadvantage of the more CO.sub.2 responsive forbs and N-fixing legumes.
On-site analysis of volatile organic compounds (VOCs) with miniaturized gas chromatography–mass spectrometry (GC–MS) systems is a very rapidly developing field of application. While, on the one hand, ...major technological advances are improving the availability of these systems on the market, on the other hand, systematic studies to assess the performance of such instruments are still lacking. To fill this gap, we compared three portable GC–MS devices to a
state-of-the-art
benchtop (stationary) system for analysis of a standard mixture of 18 VOCs. We systematically compared analytical parameters such as the sensitivity and similarity of the signal response pattern and the quality of the obtained mass spectra. We found that the investigated mobile instruments (i) showed
different response profiles
with a generally lower number of identified analytes. Also, (ii)
mass spectral reproducibility
(% relative standard deviation (RSD) of the relative abundance of selective fragments) was generally worse in the mobile devices (mean RSD for all targeted fragments ~9.7% vs. ~3.5% in the stationary system). Furthermore, mobile devices (iii) showed a poorer
mass spectral similarity
to commercial reference library spectra (>20% deviation of fragment ion relative intensity vs. ~10% in the stationary GC–MS), suggesting a less reliable identification of analytes by library search. Indeed, (iv) the performance was
better with higher-mass and/or more abundant fragments
, which should be considered to improve the results of library searches for substance identification. Finally, (v) the estimation of the signal-to-noise ratio (
S/N
) in mobile instruments as a measure of sensitivity revealed a significantly lower performance compared to the benchtop lab equipment (with a ratio among medians of ~8 times lower). Overall, our study reveals not only a poor signal-to-noise ratio and poor reproducibility of the data obtained from mobile instruments, but also unfavorable results with respect to a reliable identification of substances when they are applied for complex mixtures of volatiles.
Graphical Abstract
Prior research suggests that we may access the meaning of parafoveal words during reading. We explored how semantic‐plausibility parafoveal processing takes place in natural reading through the ...co‐registration of eye movements (EM) and fixation‐related potentials (FRPs), using the boundary paradigm. We replicated previous evidence of semantic parafoveal processing from highly controlled reading situations, extending their findings to more ecologically valid reading scenarios. Additionally, and exploring the time‐course of plausibility preview effects, we found distinct but complementary evidence from EM and FRPs measures. FRPs measures, showing a different trend than EM evidence, revealed that plausibility preview effects may be long‐lasting. We highlight the importance of a co‐registration set‐up in ecologically valid scenarios to disentangle the mechanisms related to semantic‐plausibility parafoveal processing.
In a co‐registration set‐up during natural sentence reading, we provide fixation‐related potentials & eye movements evidence of semantic parafoveal processing. Our findings demonstrate the validity of traditional contributions from highly controlled reading paradigms, while highlighting the importance of a co‐registration set‐up in ecological situations to disentangle the mechanisms behind semantic parafoveal processing.
The activation of a single C−F bond in di‐ and trifluoromethyl groups by frustrated Lewis pairs (FLPs) has been computationally explored by means of Density Functional Theory calculations. It is ...found that in this activation reaction the FLP partners exhibit a peculiar cooperative action, which is markedly different from related FLP‐mediated processes, and where non‐covalent interactions established between the Lewis base and the substrate play a decisive role. In addition, the process proceeds through the intermediacy of a hypervalent species featuring a pentacoordinate carbon atom, which is rare in the chemistry of FLPs. The physical factors controlling this process as well as the bonding situation of these hypervalent intermediates have been quantitatively analyzed in detail by using state‐of‐the‐art computational methods to not only rationalize the mechanism of the transformation but also to guide experimentalists towards the realization of these so far elusive hypervalent systems.
C−F activation: The activation of single C−F bonds in di‐ and trifluoromethyl groups mediated by frustrated Lewis pairs (FLPs) exhibits a peculiar cooperative action, which is markedly different from related FLP‐mediated processes, and where non‐covalent interactions established between the Lewis base and the substrate play a decisive role.
Expanding the performance and autonomous-decision capability of driver-assistance systems is critical in today’s automotive engineering industry to help drivers and reduce accident incidence. It is ...essential to provide vehicles with the necessary perception systems, but without creating a prohibitively expensive product. In this area, the continuous and precise estimation of a road surface on which a vehicle moves is vital for many systems. This paper proposes a low-cost approach to solve this issue. The developed algorithm resorts to analysis of vibrations generated by the tyre-rolling movement to classify road surfaces, which allows for optimizing vehicular-safety-system performance. The signal is analyzed by means of machine-learning techniques, and the classification and estimation of the surface are carried out with the use of a self-organizing-map (SOM) algorithm. Real recordings of the vibration produced by tyre rolling on six different types of surface were used to generate the model. The efficiency of the proposed model (88.54%) and its speed of execution were compared with those of other classifiers in order to evaluate its performance.
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