Adult L2 Processing and Acquisition Of The English Present Perfect

This research investigates the second language (L2) processing and acquisition of the English present perfect via two features: boundedness and current relevance. Boundedness indicates whether an action reaches an endpoint (Smith 1997; Verkuyl 1972); it divides the functions of the present perfect into sets that denote completed situations or ongoing/iterative ones (Bybee et al. 1994; Housen 2002). Current relevance indicates the present importance of a past situation (Siemund 2004); it differentiates the present perfect from the simple past (Bardovi-Harlig 2002). Previous research has relied on offline methods (that evaluate metalinguistic knowledge); no research in SLA has investigated the acquisition of the present perfect using online methods (that measure real-time processing). This investigation addresses this gap using two novel tasks. In this study, 155 adult L2 English learners of varying proficiency from three first language (L1) backgrounds (Arabic, Chinese & Other) participated; 72 L1 English speakers were controls. Online data were collected using a self-paced reading task wherein participants read sentences manipulated for grammatical tense & boundedness and for grammatical tense & current relevance. Reading time differences for each condition were analyzed by L2 proficiency and L1 group. Offline data were collected using a rating task wherein participants provide judgments concerning the meanings of phrases excerpted from similarly manipulated sentences. Rating differences were analyzed by L2 proficiency and L1 group. The results show that boundedness and current relevance affect L2 English learners’ processing and comprehension of the present perfect; first language and L2 proficiency influence these effects. In boundedness conditions, high-proficiency learners exhibit inhibited reading times in nonbounded contexts, and they more accurately rate boundedness contrasts in the present perfect. These results suggest that advanced learners can distinguish the functions of the present perfect. The Arabic group performs like higher-proficiency learners, which indicates positive L1 transfer. In current relevance conditions, only the highest proficiency group exhibits reading times affected by current relevance marking, and they understand current relevance contrasts marked adverbially and morphosyntactically; less proficient groups only comprehend current relevance contrast marked adverbially. These results suggest that less proficient learners can use adverbially marked current relevance to distinguish the present perfect and simple past; only at higher proficiency do they become sensitive to morphosyntactic current relevance marking. The Chinese group unexpectedly performs like lower proficiency learners, which indicates negative L1 transfer

Physiological recruitment of motor units by high-frequency electrical stimulation of afferent pathways

Neuromuscular electrical stimulation (NMES) is commonly used in rehabilitation, but\ua0electrically evoked muscle activation is in several ways different from\ua0voluntary muscle contractions. These differences lead to challenges in\ua0the use of NMES for restoring muscle function. We investigated the\ua0use of low-current, high-frequency nerve stimulation to activate the\ua0muscle via the spinal motoneuron (MN) pool to achieve more natural\ua0activation patterns. Using a novel stimulation protocol, the H-reflex\ua0responses to individual stimuli in a train of stimulation pulses at 100\ua0Hz were reliably estimated with surface EMG during low-level\ua0contractions. Furthermore, single motor unit recruitment by afferent\ua0stimulation was analyzed with intramuscular EMG. The results\ua0showed that substantially elevated H-reflex responses were obtained\ua0during 100-Hz stimulation with respect to a lower stimulation frequency. Furthermore, motor unit recruitment using 100-Hz stimulation was not fully synchronized, as it occurs in classic NMES, and the\ua0discharge rates differed among motor units because each unit was\ua0activated only after a specific number of stimuli. The most likely\ua0mechanism behind these observations is the temporal summation of\ua0subthreshold excitatory postsynaptic potentials from Ia fibers to the\ua0MNs. These findings and their interpretation were also verified by a\ua0realistic simulation model of afferent stimulation of a MN population.\ua0These results suggest that the proposed stimulation strategy may allowgeneration of considerable levels of muscle activation b

INVESTIGATION ON NEURAL RESPONSES RELATED TO THE LOCALIZATION OF NATURAL SOUNDS

Spatial hearing allows the localization of sounds in complex acoustic environments. There is considerable evidence that this neural system rapidly adapts to changes in sensory inputs and behavioral goals. However, the mechanisms underlying this context-dependent coding are not well understood. In fact, previous studies on sound localization have mainly focused on the perception of simple artificial sounds, such as white-noise or pure tone bursts. In addition, previous research has generally investigated the localization of sounds in the frontal hemicircle while ignoring rear sources. However, their localization is evolutionary relevant and may show different neural coding, given the inherent lack of visual information. Here we present a pilot electroencephalography (EEG) study to identify robust indices of sound localization from participants listening to a short natural sound from eight source positions on the horizontal plane. We discuss a procedure to perform a within-subject classification of the perceived sound direction. Preliminary results suggest a pool of discriminative subject-specific temporal and topographical features correlated with the characteristics of the acoustic event. Our preliminary analysis has identified temporal and topographical features that are sensitive to spatial localization, leading to significant decoding of sounds direction for individual subjects. This pilot study adds to the literature a methodological approach that will lead to the objective classification of natural sounds location from EEG responses

Electrical Stimulation of Afferent Pathways for the Suppression of Pathological Tremor

Pathological tremors are involuntary oscillatory movements which cannot be fully attenuated using conventional treatments. For this reason, several studies have investigated the use of neuromuscular electrical stimulation for tremor suppression. In a recent study, however, we found that electrical stimulation below the motor threshold also suppressed tremor, indicating involvement of afferent pathways. In this study, we further explored this possibility by systematically investigating how tremor suppression by afferent stimulation depends on the stimulation settings. In this way, we aimed at identifying the optimal stimulation strategy, as well as to elucidate the underlying physiological mechanisms of tremor suppression. Stimulation strategies varying the stimulation intensity and pulse timing were tested in nine tremor patients using either intramuscular or surface stimulation. Significant tremor suppression was observed in six patients (tremor suppression > 75% was observed in three patients) and the average optimal suppression level observed across all subjects was 52%. The efficiency for each stimulation setting, however, varied substantially across patients and it was not possible to identify a single set of stimulation parameters that yielded positive results in all patients. For example, tremor suppression was achieved both with stimulation delivered in an out-of-phase pattern with respect to the tremor, and with random timing of the stimulation. Overall, these results indicate that low-current stimulation of afferent fibers is a promising approach for tremor suppression, but that further research is required to identify how the effect can be maximized in the individual patient.This work has been supported by the Commission of the European Union through the grant ICT-2011-287739 (NeuroTREMOR).Peer reviewedPeer Reviewe

Proof of concept for multiple nerve transfers to a single target muscle

Surgical nerve transfers are used to efficiently treat peripheral nerve injuries, neuromas, phantom limb pain, or improve bionic prosthetic control. Commonly, one donor nerve is transferred to one target muscle. However, the transfer of multiple nerves onto a single target muscle may increase the number of muscle signals for myoelectric prosthetic control and facilitate the treatment of multiple neuromas. Currently, no experimental models are available. This study describes a novel experimental model to investigate the neurophysiological effects of peripheral double nerve transfers to a common target muscle. In 62 male Sprague-Dawley rats, the ulnar nerve of the antebrachium alone (n=30) or together with the anterior interosseus nerve (n=32) was transferred to reinnervate the long head of the biceps brachii. Before neurotization, the motor branch to the biceps\u27 long head was transected at the motor entry point. Twelve weeks after surgery, muscle response to neurotomy, behavioral testing, retrograde labeling, and structural analyses were performed to assess reinnervation. These analyses indicated that all nerves successfully reinnervated the target muscle. No aberrant reinnervation was observed by the originally innervating nerve. Our observations suggest a minimal burden for the animal with no signs of functional deficit in daily activities or auto-mutilation in both procedures. Furthermore, standard neurophysiological analyses for nerve and muscle regeneration were applicable. This newly developed nerve transfer model allows for the reliable and standardized investigation of neural and functional changes following the transfer of multiple donor nerves to one target muscle

Chemical Abundance of z~6 Quasar Broad-Line Regions in the XQR-30 Sample

The elemental abundances in the broad-line regions of high-redshift quasars trace the chemical evolution in the nuclear regions of massive galaxies in the early universe. In this work, we study metallicity-sensitive broad emission-line flux ratios in rest-frame UV spectra of 25 high-redshift (5.8 < z < 7.5) quasars observed with the VLT/X-shooter and Gemini/GNIRS instruments, ranging over $\log(M_{\rm{BH}}/M_{\odot})= 8.4-9.8$ in black hole mass and $\log(L_{\rm{bol}}/\rm{erg\, s}^{-1})= 46.7-47.7$ in bolometric luminosity. We fit individual spectra and composites generated by binning across quasar properties: bolometric luminosity, black hole mass, and blueshift of the \civ\, line, finding no redshift evolution in the emission-line ratios by comparing our high-redshift quasars to lower-redshift (2.0 < z < 5.0) results presented in the literature. Using Cloudy-based locally optimally-emitting cloud photoionisation model relations between metallicity and emission-line flux ratios, we find the observable properties of the broad emission lines to be consistent with emission from gas clouds with metallicity that are at least 2-4 times solar. Our high-redshift measurements also confirm that the blueshift of the CIV emission line is correlated with its equivalent width, which influences line ratios normalised against CIV. When accounting for the CIV blueshift, we find that the rest-frame UV emission-line flux ratios do not correlate appreciably with the black hole mass or bolometric luminosity.Comment: MNRAS accepted, 24 pages, 17 figures, 4 table

A comparative study of the effect of the Time for Dementia programme on medical students

Background Traditional healthcare education typically focuses on short block clinical placements based on acute care, investigations, and technical aspects of diagnosis and treatment. It may therefore fail to build the understanding, compassion, and person‐centred empathy needed to help those with long‐term conditions, like dementia. Time for Dementia was developed to address this. Method Parallel group comparison of two cohorts of UK medical students from universities, one participating in Time for Dementia (intervention group) and one not (control group). In Time for Dementia students visit a person with dementia and their family in pairs for two hours three times a year for two years, the control group received their normal curriculum. Results In an adjusted multilevel model of data (intervention group n=274, control n=112), there was strong evidence supporting improvements for Time for Dementia participants in: total Approaches to Dementia Questionnaire score (coefficient 2.19, p=0.003), and its person‐centredness subscale (1.32, p=0.006), and weaker evidence in its hopefulness subscale (0.78, p=0.070); Dementia Knowledge Questionnaire score (1.63, p<0.001); and Dementia Attitudes Scale (total score 6.55, p<0.001; social comfort subscale 4.15, p<0.001; dementia knowledge subscale 3.38, p=0.001) scores. No differences were observed on the Alzheimer's Disease Knowledge Scale, the Medical Condition Regard Scale, or the Jefferson Scale of Empathy. Discussion Time for Dementia may help improve the attitudes of medical students towards dementia promoting a person‐centred approach and increasing social comfort. Such patient‐focused programmes may be a useful complement to traditional medical education

Development of the infant foot as a load bearing structure : study protocol for a longitudinal evaluation (the Small Steps study)

Background An improved understanding of the structural and functional development of the paediatric foot is fundamental to a strong theoretical framework for health professionals and scientists. An infant’s transition from sitting, through crawling and cruising, to walking is when the structures and function of the foot must adapt to bearing load. The adaptation of skin and other hard and soft tissue, and foot and gait biomechanics, during this time is poorly understood. This is because data characterising the foot tissue and loading pre-walking onset does not exist. Of the existing kinematic and plantar pressure data, few studies have collected data which reflects the real-life activities of infants with modern equipment. Methods This is a longitudinal study and part of the Great Foundations Initiative, a collaborative project between the University of Brighton and the University of Salford, which is seeking to improve foot health in children. Two cohorts of 50 infants will be recruited at the two sites (University of Brighton, Eastbourne, UK and University of Salford, Salford, UK). Infants will be recruited when they first reach for their feet and attend four laboratory visits at milestones related to foot loading, with experienced independent walking being the final milestone. Data collection will include tissue characteristics (skin thickness, texture, elasticity, pH and tendon thickness and cross-sectional area), plantar pressures and kinematics captured during real world locomotion tasks. Discussion This study will provide a database characterising the development of the infant foot as it becomes a weight bearing structure. The data will allow effective comparison and quantification of changes in structure and function due to maturation and loading by measuring pre and post established walking. Additional variables which impact on the development of the foot (gender, ethnicity and body weight) will also be factored into our analysis. This will help us to advance understanding of the determinants of foot development in early childhood