Dzyaloshinskii-Moriya interaction in transport through single molecule transistors

The Dzyaloshinskii-Moriya interaction is shown to result in a canting of spins in a single molecule transistor. We predict non-linear transport signatures of this effect induced by spin-orbit coupling for the generic case of a molecular dimer. The conductance is calculated using a master equation and is found to exhibit a non-trivial dependence on the magnitude and direction of an external magnetic field. We show how three-terminal transport measurements allow for a determination of the coupling-vector characterizing the Dzyaloshinskii-Moriya interaction. In particular, we show how its orientation, defining the intramolecular spin chirality, can be probed with ferromagnetic electrodes

A comparison of the development of audiovisual integration in children with autism spectrum disorders and typically developing children

This study aimed to investigate the development of audiovisual integration in children with Autism Spectrum Disorder (ASD). Audiovisual integration was measured using the McGurk effect in children with ASD aged 7–16 years and typically developing children (control group) matched approximately for age, sex, nonverbal ability and verbal ability. Results showed that the children with ASD were delayed in visual accuracy and audiovisual integration compared to the control group. However, in the audiovisual integration measure, children with ASD appeared to ‘catch-up’ with their typically developing peers at the older age ranges. The suggestion that children with ASD show a deficit in audiovisual integration which diminishes with age has clinical implications for those assessing and treating these children

Reading faces: differential lateral gaze bias in processing canine and human facial expressions in dogs and 4-year-old children

Sensitivity to the emotions of others provides clear biological advantages. However, in the case of heterospecific relationships, such as that existing between dogs and humans, there are additional challenges since some elements of the expression of emotions are species-specific. Given that faces provide important visual cues for communicating emotional state in both humans and dogs, and that processing of emotions is subject to brain lateralisation, we investigated lateral gaze bias in adult dogs when presented with pictures of expressive human and dog faces. Our analysis revealed clear differences in laterality of eye movements in dogs towards conspecific faces according to the emotional valence of the expressions. Differences were also found towards human faces, but to a lesser extent. For comparative purpose, a similar experiment was also run with 4-year-old children and it was observed that they showed differential processing of facial expressions compared to dogs, suggesting a species-dependent engagement of the right or left hemisphere in processing emotions

Joule-assisted silicidation for short-channel silicon nanowire devices

We report on a technique enabling electrical control of the contact silicidation process in silicon nanowire devices. Undoped silicon nanowires were contacted by pairs of nickel electrodes and each contact was selectively silicided by means of the Joule effect. By a realtime monitoring of the nanowire electrical resistance during the contact silicidation process we were able to fabricate nickel-silicide/silicon/nickel- silicide devices with controlled silicon channel length down to 8 nm.Comment: 6 pages, 4 figure

Multifunctional Devices and Logic Gates With Undoped Silicon Nanowires

We report on the electronic transport properties of multiple-gate devices fabricated from undoped silicon nanowires. Understanding and control of the relevant transport mechanisms was achieved by means of local electrostatic gating and temperature dependent measurements. The roles of the source/drain contacts and of the silicon channel could be independently evaluated and tuned. Wrap gates surrounding the silicide-silicon contact interfaces were proved to be effective in inducing a full suppression of the contact Schottky barriers, thereby enabling carrier injection down to liquid-helium temperature. By independently tuning the effective Schottky barrier heights, a variety of reconfigurable device functionalities could be obtained. In particular, the same nanowire device could be configured to work as a Schottky barrier transistor, a Schottky diode or a p-n diode with tunable polarities. This versatility was eventually exploited to realize a NAND logic gate with gain well above one.Comment: 6 pages, 5 figure

Flop to Flip: Integrating Technology and Team-based Learning to Improve Student Engagement

Purpose: The first attempt to develop and instruct a new course in evidence-based practice in a physical therapy curriculum proved problematic. The purpose of this paper is to describe the method of revising this traditionally taught course using a combination of flipping the classroom, team-based learning, and technology. Methods: Working with an Instructional Design Specialist, a weekly online preparatory module was created for each content topic using a variety of multimedia learning provisions including micro learning videos (PowerPoint with voiceover), transcript of the PowerPoint, a list of vocabulary words, reading, Quizlet, Flipgrids and Concept Checks. Each week’s module was introduced with a listing of objectives, goals, time to complete tasks and a description of the in-class activities. Class began with a weekly 10-question vocabulary quiz to hold students accountable for their preparation. A short summary lecture followed. Students were then given an in-class assignment to complete either in pairs or small groups. Discussion of the assignment completed the session. Most of the assignments were submitted electronically prior to discussion for grading purposes. Several also utilized a team-based learning format. Pairs of students complete an assignment; students then convene with their group and discuss and complete the same assignment. This process facilitates a more active learning environment. Result: Students were consistently prepared for class as evidenced by their quiz performance. Informal assessment of the online preparatory modules was performed using a “One-Minute Paper” assessment. Students reported that the PowerPoint with voiceover, Quizlet, Concept Checks, and the weekly list of vocabulary terms were most helpful, whereas Flipgrids and reading were not helpful. In-class activities were interactive and facilitated deeper conversations about the content. Conclusion and Recommendations: The outcomes provided reflect student perception solely, which may have been biased by the instructor’s presence in the course. Formal assessment of changes was not possible using student performance as a measure because the course had dramatically changed from year one to year two. A more formal, scientific assessment is recommended to determine if and how course changes affected student performance

The Li isotope response to mountain uplift

Silicate weathering is a key process by which CO2 is removed from the atmosphere. It has been proposed that mountain uplift caused an increase in silicate weathering, and led to the long-term Cenozoic cooling trend, although this hypothesis remains controversial. Lithium isotopes are a tracer of silicate weathering processes, which may allow this hypothesis to be tested. Recent studies have demonstrated that the Li isotope ratio in seawater increased during the period of Himalayan uplift (~45 Ma), but the relationship between uplift and the Li isotope ratio of river waters has not been tested. Here we examine Li isotope ratios in rivers draining catchments with variable uplift rates from South Island, New Zealand. A negative trend between δ7Li and uplift shows that areas of rapid uplift have low δ7Li, whereas flatter floodplain areas have high δ7Li. Combined with U activity ratios, the data suggest that primary silicates are transported to floodplains, where δ7Li and (234U/238U) are driven to high values due to preferential uptake of 6Li by secondary minerals, and long fluid-mineral contact times that enrich waters in 234U. In contrast, in mountainous areas, fresh primary mineral surfaces are continuously provided, driving δ7Li and (234U/238U) low. This is the opposite trend to that expected if the increase in Cenozoic δ7Li in the oceans is driven directly by mountain uplift. These data suggests that, rather than weathering of mountain belts, the increase in seawater δ7Li reflects the formation of floodplains and the increased formation of secondary minerals

Age estimation using tooth cementum annulations: bias and sources of inaccuracy

Background: Counting the tooth cementum annulations (TCA) is a method for estimating the age at death of adults by sections of their tooth root. The objective of this study was to assess the precision of counting the cementum incremental lines and the congruence between known age and age estimates. Possible factors affecting the accuracy of the estimate were also analyzed. Methods: A sample of 67 permanent teeth extracted from individuals with known age (18 84 years) and sex was analyzed to calculate the dental age. Results: Results demonstrate an excellent inter- and intra-observer reliability of annuli counting, with dissimilarities within the limits of agreement. A moderate positive correlation was found between chronological age and TCA. Our results showed that age congruence rates differed across age groups (85% congruence in individuals <= 30 years; 75% in individuals aged 31-60 years; 60% in the over 60s). Considering the bias, this method showed a clear tendency to underestimate age in specimens from old people. After age 43, the TCA estimate is highly inaccurate exceeding the underestimation of 10 years, on average, in comparison to the chronological age. Both chronological age and dental arch seem to influence the accuracy of estimates, unlike sex and the tooth root number. Conclusions: TCA analysis is characterized by high precision and low accuracy, decreasing with age. Therefore, its applicability is limited in elderly subjects. The choice of methods for age estimation in adult skeletal remains should take into account the particular age range of individuals. We recommend using different age estimation methods to verify the reliability of the performed assessments

Dual coding with STDP in a spiking recurrent neural network model of the hippocampus.

The firing rate of single neurons in the mammalian hippocampus has been demonstrated to encode for a range of spatial and non-spatial stimuli. It has also been demonstrated that phase of firing, with respect to the theta oscillation that dominates the hippocampal EEG during stereotype learning behaviour, correlates with an animal's spatial location. These findings have led to the hypothesis that the hippocampus operates using a dual (rate and temporal) coding system. To investigate the phenomenon of dual coding in the hippocampus, we examine a spiking recurrent network model with theta coded neural dynamics and an STDP rule that mediates rate-coded Hebbian learning when pre- and post-synaptic firing is stochastic. We demonstrate that this plasticity rule can generate both symmetric and asymmetric connections between neurons that fire at concurrent or successive theta phase, respectively, and subsequently produce both pattern completion and sequence prediction from partial cues. This unifies previously disparate auto- and hetero-associative network models of hippocampal function and provides them with a firmer basis in modern neurobiology. Furthermore, the encoding and reactivation of activity in mutually exciting Hebbian cell assemblies demonstrated here is believed to represent a fundamental mechanism of cognitive processing in the brain

No rapid audiovisual recalibration in adults on the autism spectrum

Autism spectrum disorders (ASD) are characterized by difficulties in social cognition, but are also associated with atypicalities in sensory and perceptual processing. Several groups have reported that autistic individuals show reduced integration of socially relevant audiovisual signals, which may contribute to the higher-order social and cognitive difficulties observed in autism. Here we use a newly devised technique to study instantaneous adaptation to audiovisual asynchrony in autism. Autistic and typical participants were presented with sequences of brief visual and auditory stimuli, varying in asynchrony over a wide range, from 512 ms auditory-lead to 512 ms auditory-lag, and judged whether they seemed to be synchronous. Typical adults showed strong adaptation effects, with trials proceeded by an auditory-lead needing more auditory-lead to seem simultaneous, and vice versa. However, autistic observers showed little or no adaptation, although their simultaneity curves were as narrow as the typical adults. This result supports recent Bayesian models that predict reduced adaptation effects in autism. As rapid audiovisual recalibration may be fundamental for the optimisation of speech comprehension, recalibration problems could render language processing more difficult in autistic individuals, hindering social communication