Innervation zone shift at different levels of isometric contraction in the biceps brachii muscle

Experiments were carried out to examine whether innervation zone (IZ) location remains stable at different levels of isometric contraction in the biceps brachii muscle (BB), and to determine how the proximity of the IZ affects common surface electromyography (sEMG) parameters. Twelve subjects performed maximal (MVC) and submaximal voluntary isometric contractions at 10%, 20%, 30%, 40%, 50% and 75% of MVC. sEMG signals were recorded with a 13 rows  5 columns grid of electrodes from the short head of BB. The IZ shifted in the proximal direction by up to 2.4 cm, depending upon the subject and electrode column. The mean shift of all the columns was 0.6 ± 0.4 cm (10% vs. 100% MVC, P < 0.001). This shift biased the average values of mean frequency (+21.8 ± 9.9 Hz, P < 0.001), root mean square (0.16 ± 0.15 mV, P < 0.05) and conduction velocity (1.15 ± 0.93 m/s, P < 0.01) in the channels immediately proximal to the IZ. The shift in IZ could be explained by shortening of the muscle fibers, and thus lengthening of the (distal) tendon due to increasing force. These results underline the importance of individual investigation of IZ locations before the placement of sEMG electrodes, even in isometric contractions.

Correlation between shoulder flow zone quality and material flow quantity during friction stir welding of thick aluminum section using scroll shoulder tool

The so-called scroll shoulder tool is widely used particularly for thick section friction stir welding (FSW). However, the correlation between its shoulder flow zone weld quality and material flow quantity remains unclear. This information is important for tool design. In the present study, a scroll shoulder tool was used to FSW 20mm thick 6061 aluminum (Al) plates at a range of welding parameters. The pick-up material (PUM) by the scroll was quantified, and the effect of welding parameters and PUM on the shoulder flow zone formation and weld quality was studied. It was found that there is a positive linear relationship between the PUM and weld quality. In order to obtain a defect-free FSW weld produced by the scroll shoulder tool, scroll groove needs to be fully filled by PUM.

Material flow forming the shoulder flow zone using scroll shoulder tool during friction stir welding of thick section aluminum alloys

Scroll shoulder tools are widely used and they do not need to be tilted during friction stir welding (FSW). However, the detailed material flow, which is important for proper scroll shoulder tool design and subsequently for forming the defect-free shoulder flow zone, has not been fully explained. In the present study, features of material flow in shoulder flow zone, during FSW of thick 6061 aluminium (Al) plates using a scroll shoulder tool were investigated. It was observed that there is a simple layer-to-layer banded structure which appears in the bottom portion of shoulder flow zone, but disappears in the top portion of this weld zone. When the scroll shoulder tool is plunged into the workpiece to a determined depth, the workpiece material is extruded by the tool pin, and pushed up into the scroll groove beneath the shoulder forming the pick-up material. During the forward movement of the tool, the central portion of pick-up material was driven downward by the root portion of pin and then it detaches from the tip portion of pin in a layer-to-layer manner to form the weld.

The Carboniferous and Permian sequences in north and south of the Longmucuo-Shuanghu suture zone in Tibet

The location of the Palaeo-tethys suture in Tibet has been in great dispute for past two decades. The Longmucuo-Shuanghu suture has long been considered as the Palaeo-tethys in Tibet. Restudy of the Carboniferous and Permian sequences in the north and south of this suture reveal that: (1) the Carboniferous and Permian sequence of the North Qiangtang Block is characterized by containing compound corals and intact fusulinids zones from Moscovian Fusulinella, Fusulina to Changhsingian Palaeofusulina zones; (2) the Early Permian of the South Qiangtang Block is

Inexplicable inefficiency of avian molt? Insights from an opportunistically breeding arid-zone species, Lichenostomus penicillatus

The majority of bird species studied to date have molt schedules that are not concurrent with other energy demanding life history stages, an outcome assumed to arise from energetic trade-offs. Empirical studies reveal that molt is one of the most energetically demanding and perplexingly inefficient growth processes measured. Furthermore, small birds, which have the highest mass-specific basal metabolic rates (BMR_m), have the highest costs of molt per gram of feathers produced. However, many small passerines, including white-plumed honeyeaters (WPHE; Lichenostomus penicillatus), breed in response to resource availability at any time of year, and do so without interrupting their annual molt. We examined the energetic cost of molt in WPHE by quantifying weekly changes in minimum resting metabolic rate (RMR_min) during a natural-molt period in 7 wild-caught birds. We also measured the energetic cost of feather replacement in a second group of WPHEs that we forced to replace an additional 25% of their plumage at the start of their natural molt period. Energy expenditure during natural molt revealed an energy conversion efficiency of just 6.9% (±0.57) close to values reported for similar-sized birds from more predictable north-temperate environments. Maximum increases in RMR_min during the molt of WPHE, at 82% (±5.59) above individual pre-molt levels, were some of the highest yet reported. Yet RMR_min maxima during molt were not coincident with the peak period of feather replacement in naturally molting or plucked birds. Given the tight relationship between molt efficiency and mass-specific metabolic rate in all species studied to date, regardless of life-history pattern (Efficiency (%) = 35.720•10^-0.494BMRm; r² = 0.944; p =<0.0001), there appears to be concomitant physiological costs entrained in the molt period that is not directly due to feather replacement. Despite these high total expenditures, the protracted molt period of WPHE significantly reduces these added costs on a daily basis.

‘No one will ever know...’ : the Holocaust, ‘privileged’ Jews, and the ‘grey zone’

This paper explores the problems of judgement and representation in relation to Jewish victims of the Holocaust who occupied so-called privileged positions in the camps and ghettos. Such figures, forced to act in ways that have proven controversial both during and after the war, faced unprecedented ethical dilemmas under Nazi persecution. Taking Auschwitz survivor Primo Levi’s highly influential essay on the ‘grey zone’ as a point of departure, I examine the extreme situations confronted by prisoner doctors, an important – though little discussed – category of ‘privileged’ Jews. Investigating the synergies between history, memory and film, I focus particularly on the case of Gisella Perl, a prisoner doctor whose experiences in Auschwitz-Birkenau are represented in her memoir and a recent fiction film. The emotionally and morally fraught circumstances of prisoner doctors can never be fully understood, yet reflecting on the double binds they faced, and acknowledging the inherent problems involved in representing and judging them, enables a nuanced approach to the moral complexities of the Holocaust.

Towards an improved understanding of knowledge dynamics in integrated coastal zone management: a knowledge systems framework

Integrated coastal zone management (ICZM) is a complex undertaking that draws on a range of biophysical and social science disciplines, and involves a wide range of stakeholders operating through multiple processes, and crossing various levels  Conceptually, this means that ICZM represents a significant challenge in terms of improving the way in which different disciplinary ‘knowledges’ and different forms of knowledge (scientific, managerial, lay, and indigenous) inform decision making. Depending upon the circumstances, ICZM may be constrained by different knowledge deficits, including: uncertainty; science - policy gaps; and the ‘filtering’ of particular forms of knowledge relative to others. As a means for making sense of these knowledge dynamics, this paper considers the concept of knowledge systems and its potential for improving understanding of coastal management processes. The potential insights that can be gained from four analytical approaches (stakeholder, institutional, network, and discourse analysis) are then discussed, and used to develop an analytical framework for investigating coastal knowledge dynamics, which is based upon a generic coastal knowledge system and associated research questions. Finally, the utility of this framework is illustrated using a case study that examines the knowledge dynamics associated with debates about the establishment of marine protected areas in Victoria, Australia.

Improving science uptake in coastal zone management : principles for science engagement and their application in south-eastern Tasmania

Sustainable management of the coastal zone represents a considerable challenge to Australian society. This challenge is rooted in the complexity of the biophysical and sociocultural characteristics of coastal areas, including uncertainty about system characteristics and processes, and the diversity of stakeholders, their interests, values and perspectives, and the jurisdictions involved in coastal governance and management. Given this complexity of coastal zone management, scientific and other forms of knowledge can affect decision-making and human action in diverse ways, which will often depend on the ability of scientists to engage effectively with relevant stakeholders.