► The mirror neuron system sub-serves both motor imagery and action observation. ► Both motor imagery and action observation play a role in motor learning. ► In this study we compared these ...strategies in learning a novel complex motor task. ► Action observation revealed better than motor imagery as a motor learning strategy. ► This is relevant in educational activities, sport training and neurorehabilitation.
Both motor imagery and action observation have been shown to play a role in learning or re-learning complex motor tasks. According to a well accepted view they share a common neurophysiological basis in the mirror neuron system. Neurons within this system discharge when individuals perform a specific action and when they look at another individual performing the same or a motorically related action. In the present paper, after a short review of literature on the role of action observation and motor imagery in motor learning, we report the results of a kinematics study where we directly compared motor imagery and action observation in learning a novel complex motor task. This involved movement of the right hand and foot in the same angular direction (in-phase movement), while at the same time moving the left hand and foot in an opposite angular direction (anti-phase movement), all at a frequency of 1Hz. Motor learning was assessed through kinematics recording of wrists and ankles. The results showed that action observation is better than motor imagery as a strategy for learning a novel complex motor task, at least in the fast early phase of motor learning. We forward that these results may have important implications in educational activities, sport training and neurorehabilitation.
► There are no experimental evidence on how the brain processes adjectives. ► We applied TMS while subjects were reading adjectives, expressing negative or positive features. ► We recorded MEPs from ...two antagonist muscles, one involved in grasping, the other in releasing. ► Depending on their function, muscle activity was differently modulated by the used adjectives. ► These results are well explained by an embodied approach to language processing.
Using transcranial magnetic stimulation (TMS), motor evoked potentials (MEPs) were recorded from two antagonistic muscles, the first dorsal interosseus (FDI) of the hand and the extensor communis digitorum (EC) of the forearm. FDI is involved in grasping actions and EC in releasing. TMS pulses were delivered while participants were reading adjectives expressing either negative or positive pragmatic properties, at 150ms after presentation of language material. Overall findings showed an interaction of adjective type (positive, negative) and muscle (FDI, EC), the effect being driven by a significant difference for negative adjectives. Further analysis aimed at investigating the effectiveness of positive adjectives showed a similar, but opposite, pattern of effects for the positive words in the initial two blocks. The present results indicate that, as for verbs and nouns, adjectives recruit the sensorimotor system, and their processing is best explained by an embodiment rather than an amodal approach to language.
Soils are warming as air temperatures rise across the Arctic and Boreal region concurrent with the expansion of tall-statured shrubs and trees in the tundra. Changes in vegetation structure and ...function are expected to alter soil thermal regimes, thereby modifying climate feedbacks related to permafrost thaw and carbon cycling. However, current understanding of vegetation impacts on soil temperature is limited to local or regional scales and lacks the generality necessary to predict soil warming and permafrost stability on a pan-Arctic scale. Here we synthesize shallow soil and air temperature observations with broad spatial and temporal coverage collected across 106 sites representing nine different vegetation types in the permafrost region. We showed ecosystems with tall-statured shrubs and trees (>40 cm) have warmer shallow soils than those with short-statured tundra vegetation when normalized to a constant air temperature. In tree and tall shrub vegetation types, cooler temperatures in the warm season do not lead to cooler mean annual soil temperature indicating that ground thermal regimes in the cold-season rather than the warm-season are most critical for predicting soil warming in ecosystems underlain by permafrost. Our results suggest that the expansion of tall shrubs and trees into tundra regions can amplify shallow soil warming, and could increase the potential for increased seasonal thaw depth and increase soil carbon cycling rates and lead to increased carbon dioxide loss and further permafrost thaw.
This is a review paper that surveys past work in, and the recent status of, active synthetic aperture sonar (SAS). It covers the early historical development of SAS with its provenance in synthetic ...aperture radar (SAR) and flows through into what work has been published in the open literature up to early 2007. The list of references is sufficiently complete to include most past and recent SAS publications in the open refereed literature.
The association between current use of oral contraceptives and increased risk of venous thromboembolism (VTE) has been firmly established. Although data-sheets for hormone replacement therapy (HRT) ...carry similar warnings as regards VTE, evidence of an association is inconclusive. We carried out a hospital-based case-control study to investigate whether current use of HRT is associated with VTE.
We screened all women aged 45–64 years admitted to hospitals in the area of the Oxford Regional Health Authority with a suspected diagnosis of VTE between February, 1993, and December, 1994. We recruited 81 cases of idiopathic VTE and 146 hospital controls with disorders of eyes, skin, ears, respiratory and alimentary tracts, kidneys, bones, and joints, and trauma; controls were matched to cases for age-group and date and district of admission. To increase the study power, an additional 22 cases of idiopathic VTE and 32 hospital controls admitted before February, 1993, were recruited retrospectively. Participants were questioned about medical and gynaecological history, use of oral contraceptives and HRT, use of other drugs within the previous 3 months, and lifestyle and socioeconomic characteristics. Detailed diagnostic data were extracted from the notes of eligible cases. Matched analyses, adjusted for body-mass index, socioeconomic group, and history of varicose veins, were undertaken by conditional logistic regression.
44 (42·7%) cases and 44 (24·7%) controls were current users of HRT. The adjusted odds ratio for VTE in current users of HRT compared with non-users (never-users and past users combined) was 3·5 (95% CI 1·8–7·0; p<0·001). No association was found with past use, and risk appeared to be highest among short-term current users (adjusted likelihood ratio test of trend in odds ratios across different durations of current use, p=0·011).
Current HRT use is associated with risk of VTE. The increased risk may be concentrated in new users. The number of extra cases appears to be only about one in 5000 users per year. These findings need to be weighed against the probable benefits of long-term treatment, including reductions in risks of osteoporotic fracture and coronary heart disease, and the probable modest increase in risk of breast cancer.
Background
The erosion of the early mortality advantage of elective endovascular aneurysm repair (EVAR) compared with open repair of abdominal aortic aneurysm remains without a satisfactory ...explanation.
Methods
An individual‐patient data meta‐analysis of four multicentre randomized trials of EVAR versus open repair was conducted to a prespecified analysis plan, reporting on mortality, aneurysm‐related mortality and reintervention.
Results
The analysis included 2783 patients, with 14 245 person‐years of follow‐up (median 5·5 years). Early (0–6 months after randomization) mortality was lower in the EVAR groups (46 of 1393 versus 73 of 1390 deaths; pooled hazard ratio 0·61, 95 per cent c.i. 0·42 to 0·89; P = 0·010), primarily because 30‐day operative mortality was lower in the EVAR groups (16 deaths versus 40 for open repair; pooled odds ratio 0·40, 95 per cent c.i. 0·22 to 0·74). Later (within 3 years) the survival curves converged, remaining converged to 8 years. Beyond 3 years, aneurysm‐related mortality was significantly higher in the EVAR groups (19 deaths versus 3 for open repair; pooled hazard ratio 5·16, 1·49 to 17·89; P = 0·010). Patients with moderate renal dysfunction or previous coronary artery disease had no early survival advantage under EVAR. Those with peripheral artery disease had lower mortality under open repair (39 deaths versus 62 for EVAR; P = 0·022) in the period from 6 months to 4 years after randomization.
Conclusion
The early survival advantage in the EVAR group, and its subsequent erosion, were confirmed. Over 5 years, patients of marginal fitness had no early survival advantage from EVAR compared with open repair. Aneurysm‐related mortality and patients with low ankle : brachial pressure index contributed to the erosion of the early survival advantage for the EVAR group. Trial registration numbers: EVAR‐1, ISRCTN55703451; DREAM (Dutch Randomized Endovascular Aneurysm Management), NCT00421330; ACE (Anévrysme de l'aorte abdominale, Chirurgie versus Endoprothèse), NCT00224718; OVER (Open Versus Endovascular Repair Trial for Abdominal Aortic Aneurysms), NCT00094575.
Survival comparable
The Kohistan arc terrane comprises an intra‐oceanic island arc of Cretaceous age separating the Indian plate to the south from the Karakoram (Asian) plate to the north within the Indus suture zone of ...north Pakistan. The intra‐oceanic arc volcanics (Chalt, Dras Group) were built on a foundation of dominantly mid‐ocean ridge basalt (MORB)‐related amphibolites of the Kamila Group. The subarc magma chamber is represented by multiple intrusions of a huge gabbro‐norite complex (Chilas complex), which includes some ultramafic assemblages of residual mantle harzburgite and dunite, layered cumulates, and hornblendites cut by late stage dikes of hornblende + plagioclase pegmatites. The Chilas complex norites intrude the Gilgit metasediments of lower amphibolite and greenschist facies in northern Kohistan, which also form xenolithic roof pendants within the top of the Chilas complex. Along the southern margin of Kohistan, Jijal and Sapat complex ultramafics (dunites, harzburgites and websterites) form remnant suprasubduction zone ophiolitic mantle rocks along the hanging wall of the Main Mantle Thrust, the Cretaceous obduction plane along which Kohistan was emplaced onto Indian plate rocks. Garnet granulites of the Jijal complex, formed at 12–14 kbars, represent original magmatic lower crustal rocks subducted to depths of at least 45 km and metamorphosed during high‐pressure and high‐temperature subduction of earlier arc‐related rocks. Obduction of the Sapat ophiolite and Kohistan arc occurred between ∼75 and 55 Ma.
The closure of the Shyok suture zone separating Kohistan from the Karakoram plate must have occurred prior to 75 Ma, the age of the Jutal basic dikes which crosscut the closure‐related fabrics, mainly late north directed backthrusting in the lower Hunza valley. Andean‐type granitoid (gabbrodiorite‐granodiorite‐granite) emplacement along the Kohistan‐Ladakh batholith ended at the time of India‐Asia collision, ∼ 60–50 Myr ago. Postcollisional crustal thickening along the Karakoram led to multiple episodes of metamorphism from latest Cretaceous and throughout the Tertiary. Sillimanite grade metamorphism in Hunza was actually pre‐India‐Asia collision and may have resulted from the earlier Kohistan collision. Localized and sporadic crustal melting episodes across northern Kohistan (Indus confluence and Parri granite sheets) and the southern Karakoram (Hunza dikes and Sumayar and Mango Gusar leucogranites) occurred from 51 to 9 Ma and culminated in the huge Baltoro monzogranite‐leucogranite intrusion 25–21 Myr ago. A vast network of leucogranitic and pegmatitite dikes containing gem quality aquamarine + muscovite ± tourmaline ± garnet ± biotite quartz are younger than 5 Ma and form the final phase of intrusion in the Haramosh area and parts of the southern Karakoram area.
Two glass-ceramic scaffolds with a simple cubic structure of 500 µm square ligaments and square channels of width 400 or 600 µm have been fabricated by gel-casting into moulds produced by ...stereolithography, followed by mould removal, polymer burnout and sintering. The scaffolds have crushing strengths of 41 ± 14 and 17 ± 5 Mpa, respectively. Using a method of assembling discrete slices of scaffold, we are able to study cell behaviour within a scaffold by disassembly. Both scaffold structures were seeded with primary human osteoblasts and these penetrate, adhere, spread and proliferate on the scaffold structure. The larger channel diameter scaffold shows a greater cell population (despite its smaller surface area) and more pronounced production of ECM components (collagen and mineralization) with increased time in culture. Studies of sectioned scaffolds show that cell density and ECM production decrease with depth and that the difference between the two scaffold architectures is maintained.
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