Optic flow in human vision: MEG reveals a foveo-fugal bias in V1, specialization for spiral space in hMSTs, and global motion sensitivity in the IPS

Abstract We recorded MEG responses from 17 participants viewing random-dot patterns simulating global optic flow components (expansion, contraction, rotation, deformation, and translation) and a random motion control condition. Theta-band (3–7 Hz), MEG signal power was greater for expansion than the other optic flow components in a region concentrated along the calcarine sulcus, indicating an ecologically valid, foveo-fugal bias for unidirectional motion sensors in V1. When the responses to the optic flow components were combined, a decrease in MEG beta-band (17–23 Hz) power was found in regions extending beyond the calcarine sulcus to the posterior parietal lobe (inferior to IPS), indicating the importance of structured motion in this region. However, only one cortical area, within or near the V5/hMT+ complex, responded to all three spiral-space components (expansion, contraction, and rotation) and showed no selectivity for global translation or deformation: we term this area hMSTs. This is the first demonstration of an exclusive region for spiral space in the human brain and suggests a functional role better suited to preliminary analysis of ego-motion than surface pose, which would involve deformation. We also observed that the rotation condition activated the cerebellum, suggesting its involvement in visually mediated control of postural adjustment.

An analysis of fatal accidents in agriculture in Great Britain

The number of fatal accidents in the agricultural, horticultural and forestry industry in Great Britain has declined from an annual rate of about 135 in the 1960's to its current level of about 50. Changes to the size and makeup of the population at risk mean that there has been no real improvement in fatal injury incidence rates for farmers. The Health and Safety Executives' (HSE) current system of accident investigation, recording, and analysis is directed primarily at identifying fault, allocating blame, and punishing wrongdoers. Relatively little information is recorded about the personal and organisational factors that contributed to, or failed to prevent accidents. To develop effective preventive strategies, it is important to establish whether errors by the victims and others, occur at the skills, rules, or knowledge level of functioning: are violations of some rule or procedure; or stem from failures to correctly appraise, or control a hazard. A modified version of the Hale and Glendon accident causation model was used to study 230 fatal accidents. Inspectors' original reports were examined and expert judgement applied to identify and categorise the errors committed by each of the parties involved. The highest proportion of errors that led directly to accidents occurred whilst the victims were operating at the knowledge level. The mix and proportion of errors varied considerably between different classes of victim and kind of accident. Different preventive strategies will be needed to address the problem areas identified.

Relevance of motion artifact in electromyography recordings during vibration treatment

Electromyography readings (EMGs) from quadriceps of fifteen subjects were recorded during whole body vibration treatment at different frequencies (10-50 Hz). Additional electrodes were placed on the patella to monitor the occurrence of motion artifact, triaxial accelerometers were placed onto quadriceps to monitor motion. Signal spectra revealed sharp peaks corresponding to vibration frequency and its harmonics, in accordance with the accelerometer data. EMG total power was compared to that associated with vibration harmonics narrow bands, before and during vibration. On average, vibration associated power resulted in only 3% (±0.9%) of the total power prior to vibration and 29% (±13.4%) during vibration. Often, studies employ surface EMG to quantitatively evaluate vibration evoked muscular activity and to set stimulation frequency. However, previous research has not accounted for motion artifacts. The data presented in this study emphasize the need for the removal of motion artifacts, as they consistently affect RMS estimation, which is often used as a concise muscle activity index during vibrations. Such artifacts, rather unpredictable in amplitude, might be the cause of large inter-study differences and must be eliminated before analysis. Motion artifact filtering will contribute to thorough and precise interpretation of neuromuscular response to vibration treatment. © 2008 Elsevier Ltd. All rights reserved.

Extrinsic factors in the perception of bistable motion stimuli

When viewing a drifting plaid stimulus, perceived motion alternates over time between coherent pattern motion and a transparent impression of the two component gratings. It is known that changing the intrinsic attributes of such patterns (e.g. speed, orientation and spatial frequency of components) can influence percept predominance. Here, we investigate the contribution of extrinsic factors to perception; specifically contextual motion and eye movements. In the first experiment, the percept most similar to the speed and direction of surround motion increased in dominance, implying a tuned integration process. This shift primarily involved an increase in dominance durations of the consistent percept. The second experiment measured eye movements under similar conditions. Saccades were not associated with perceptual transitions, though blink rate increased around the time of a switch. This indicates that saccades do not cause switches, yet saccades in a congruent direction might help to prolong a percept because i) more saccades were directionally congruent with the currently reported percept than expected by chance, and ii) when observers were asked to make deliberate eye movements along one motion axis, this increased percept reports in that direction. Overall, we find evidence that perception of bistable motion can be modulated by information from spatially adjacent regions, and changes to the retinal image caused by blinks and saccades.

The role of the English language in the context of national development vision 2025 with specific reference to agriculture in Tanzania

After thirty years of vacillation, the Tanzanian government has made a firm decision to Swahilize its secondary education system. It has also embarked on an ambitious economic and social development programme (Vision 2025) to transform its peasant society into a modern agricultural community. However, there is a faction in Tanzania opposed to Kiswahili as the medium of education. Already many members of the middle and upper class their children to English medium primary schools to avoid the Kiswahili medium public schools and to prepare their children for the English medium secondary system presently in place. Within the education system, particularly at university level, there is a desire to maintain English as the medium of education. English is seen to provide access to the international scientific community, to cutting edge technology and to the global economy. My interest in this conflict of interests stems from several years' experience teaching English to students at Sokoine University of Agriculture. Students specialise in agriculture and are expected to work with the peasant population on graduation. The students experience difficulties studying in English and then find their Kiswahili skills insufficient to explain to farmers the new techniques and technologies that they have studied in English. They are hampered by a complex triglossic situation in which they use their mother tongue with family and friends, Kiswahili, the national language for early education and most public communication within Tanzania, and English for advanced studies. My aim in this thesis was - to study the language policy in Tanzania and see how it is understood and implemented; - to examine the attitudes towards the various languages and their various roles; - to investigate actual language behaviour in Tanzanian higher education. My conclusion is that the dysfunctionality of the present study has to be addressed. Diglossic public life in Tanzania has to be accommodated. The only solution appears to be a compromise, namely a bilingual education system which supports from all cases of society by using Kiswahili, together with an early introduction of English and its promotion as a privileged foreign language, so that Tanzania can continue to develop internally through Kiswahili and at the same time retain access to the globalising world through the medium of English.

Depth propagation and surface construction in 3-D vision

Motion discontinuities can signal object boundaries where few or no other cues, such as luminance, colour, or texture, are available. Hence, motion-defined contours are an ecologically important counterpart to luminance contours. We developed a novel motion-defined Gabor stimulus to investigate the nature of neural operators analysing visual motion fields in order to draw parallels with known luminance operators. Luminance-defined Gabors have been successfully used to discern the spatial-extent and spatial-frequency specificity of possible visual contour detectors. We now extend these studies into the motion domain. We define a stimulus using limited-lifetime moving dots whose velocity is described over 2-D space by a Gabor pattern surrounded by randomly moving dots. Participants were asked to determine whether the orientation of the Gabor pattern (and hence of the motion contours) was vertical or horizontal in a 2AFC task, and the proportion of correct responses was recorded. We found that with practice participants became highly proficient at this task, able in certain cases to reach 90% accuracy with only 12 limited-lifetime dots. However, for both practised and novice participants we found that the ability to detect a single boundary saturates with the size of the Gaussian envelope of the Gabor at approximately 5 deg full-width at half-height. At this optimal size we then varied spatial frequency and found the optimum was at the lowest measured spatial frequency (0.1 cycle deg-1 ) and then steadily decreased with higher spatial frequencies, suggesting that motion contour detectors may be specifically tuned to a single, isolated edge.

The role of trust in the transition from traditional to electronic B2B relationships in agri-food chains

E-business adoption rates in the agri-food sector are rather low, despite the fact that technical barriers have been mostly overcome during the last years and a large number of sophisticated offers are available. However, concerns about trust seem to impede the development of electronic relationships in the agri-food chains as trust is of particular importance in any exchange of agri-food products along the value chain. Drawing on existing research, characteristics and dimensions of trust are initially identified both in traditional and in electronic B2B relationships and a typology of trust is proposed. The aim of the paper is to provide an overview of the implementation and use of trust elements that e-commerce offers dedicated to agri-food sector. This assessment will show the current situation and discuss gaps for further improvement with the objective to facilitate the uptake of e-commerce in agri-food chains. © 2009 Elsevier B.V. All rights reserved.

Concentration of mannitol and other soluble carbohydrates in the crustose lichen Rhizocarpon geographicum

In symbiotic lichens which have Trebouxia as the algal partner, photosynthesis by the algae results in the production of the soluble carbohydrate ribitol which is then transported to the fungus where it is converted to arabitol and mannitol. Within the fungus, arabitol may act as a short-term carbohydrate reserve while mannitol may have a more protective function and be important in stress resistance. The concentrations of ribitol, arabitol, and mannitol were measured, using gas chromatography, in the central areolae and marginal hypothallus of the crustose lichen Rhizocarpon geographicum (L.) DC. growing on slate rocks in north Wales, UK. The concentrations of all three soluble carbohydrates were greater in the central areolae than in the marginal prothallus. In addition, the ratio of mannitol in the prothallus to that in the areolae was least in July. The concentration of an individual carbohydrate in the prothallus was correlated primarily with the concentrations of the other carbohydrates in the prothallus and not to their concentrations in the areolae. Low concentration of ribitol, arabitol, and mannitol in the marginal prothallus compared with the central areolae suggests either a lower demand for carbohydrate by the prothallus or limited transport from areolae to prothallus and may explain the low growth rates of this species. In addition, soluble carbohydrates appear to be partitioned differently through the year with an increase in mannitol compared with arabitol in more stressful periods.

From syntatic standards to semantic standards in the agri-food logistics domain

This paper identifies gaps in standardization of agri-food logistics. Out of the European FP7 SmartAgriFood project a framework for classifying existing standards within the agri-food supply chain is introduced. Furthermore the characteristics to which a semantic standard should adhere are investigated. The standards classified as semantic out of the framework are assessed along these properties. The resulting conclusion is that the standards that are already present in the chain are more focused on syntax and lack semantic properties.

The representation of food in social media forum Twitter

Social Media is becoming an increasingly important part of people’s lives and is being used increasingly in the food and agriculture sector. This paper considers the extent to which each section of the food supply chain is represented in Twitter and use the hashtag #food. We looked at the 20 most popular words for each part of the supply chain by categorising 5000 randomly selected tweets to different sections of the food chain and then analysing each category. We sorted the users by those who tweeted most frequently and categorised their position in the food supply chain. Finally to consider the indegree of influence, we took the top 100 tweeters from the previous list and consider what following these users have. From this we found that consumers are the most represented area of the food chain, and logistics is the least represented. Consumers had 51.50% of the users and 87.42% of the top words tweeted from that part of the food chain. We found little evidence of logistics representation for either tweets or users (0.84% and 0.35% respectively). The top users were found to follow a high percentage of their own followers with most having over 70% the same. This research will bring greater understanding of how people perceive the food sector and how Twitter can be used within this sector.

False recognition of objects in visual scenes:findings from a combined direct and indirect memory test

We report an extension of the procedure devised by Weinstein and Shanks (Memory & Cognition 36:1415-1428, 2008) to study false recognition and priming of pictures. Participants viewed scenes with multiple embedded objects (seen items), then studied the names of these objects and the names of other objects (read items). Finally, participants completed a combined direct (recognition) and indirect (identification) memory test that included seen items, read items, and new items. In the direct test, participants recognized pictures of seen and read items more often than new pictures. In the indirect test, participants' speed at identifying those same pictures was improved for pictures that they had actually studied, and also for falsely recognized pictures whose names they had read. These data provide new evidence that a false-memory induction procedure can elicit memory-like representations that are difficult to distinguish from "true" memories of studied pictures. © 2012 Psychonomic Society, Inc.