Do challenge, task experience or computer familiarity influence the learning of historical chronology from virtual environments in 8-9 year old children?

Studies examined the potential use of VEs in teaching historical chronology to 127 children of primary school age (8-9 years). The use of passive fly-through VEs had been found, in an earlier study, to be disadvantageous with this age group when tested for their subsequent ability to place displayed sequential events in correct chronological order. All VEs in the present studies included active challenge, previously shown to enhance learning in older participants. Primary school children in the UK (all frequent computer users) were tested using UK historical materials, but no significant effect was found between three conditions (Paper, PowerPoint and VE) with minimal pre-training. However, excellent (error free) learning occurred when children were allowed greater exploration prior to training in the VE. In Ukraine, with children having much less computer familiarity, training in a VE (depicting Ukrainian history) produced better learning compared to PowerPoint, but no better than in a Paper condition. The results confirmed the benefit of using challenge in a VE with primary age children, but only with adequate prior familiarisation with the medium. Familiarity may reduce working memory load and increase children’s spatial memory capacity for acquiring sequential temporal-spatial information from virtual displays.     

Cover picture: proteomics 7-8'12

Over recent years, advances in proteomic technologies have led to the rapid generation of vast volumes of data regarding many clinical applications, acquired from cells through to patients. High-throughput analysis of protein-protein interactions, quantification of protein abundance, global analysis of posttranslational modifications and other approaches have addressed the complexity of cellular regulation in health and disease, which has opened the way to systems-level clinical research. The dysregulation of cell adhesion plays a key role in many disease states. The image represents a systematic analysis of integrin adhesion complexes, which were isolated from erythroleukemia cells and analyzed bymass spectrometry (see Byron et al., Science Signaling 2011, 4, pt2). To understand how specific adhesion complexes may function, the composition of different complexes was compared using hierarchical clustering, and a protein-protein interaction network model of the core receptor-bound subcomplex was constructed. Data-driven, global investigations such as this could pave the road to new therapeutic targets and personalized medicines. Cover image created by Adam Byron (University of Manchester,Manchester, UK); cover design by SCHULZ Grafik-Design.     

International standards on working postures and movements ISO 11226 and EN 1005-4

Standards organizations have given considerable attention to the problem of work-related musculoskeletal disorders. The publication of international standards for evaluating working postures and movements, ISO 11,226 in 2000 and EN 1,005-4 in 2005, may be considered as a support for those involved in preventing and controlling these disorders. The first one is a tool for evaluation of existing work situations, whereas the latter one is a tool for evaluation during a design/engineering process. Key publications and considerations that led to the content of the standards are presented, followed by examples of application.     

Visual recognition of continuous hand postures

This paper describes GREFIT (Gesture REcognition based on FInger Tips), a neural network-based system which recognizes continuous hand postures from gray-level video images (posture capturing). Our approach yields a full identification of all finger joint angles (making, however, some assumptions about joint couplings to simplify computations). This allows a full reconstruction of the three-dimensional (3-D) hand shape, using an articulated hand model with 16 segments and 20 joint angles. GREFIT uses a two-stage approach to solve this task. In the first stage, a hierarchical system of artificial neural networks (ANNs) combined with a priori knowledge locates the two-dimensional (2-D) positions of the finger tips in the image. In the second stage, the 2-D position information is transformed by an ANN into an estimate of the 3-D configuration of an articulated hand model, which is also used for visualization. This model is designed according to the dimensions and movement possibilities of a natural human hand. The virtual hand imitates the user's hand to an remarkable accuracy and can follow postures from gray scale images at a frame rate of 10 Hz.     

An OWAS-based analysis of nurses' working postures

Abstract

The working postures of Dutch nurses (n = 18) in an orthopaedic ward and a urology ward were observed using-the Ovako Working posture Analysis System (OWAS). During observation, both working postures and activities were recorded. A specially developed computer program was used for data analysis. By means of this program, it was possible to calculate the working posture load for each activity and the contribution of a specific activity to the total working posture load. This study shows that some activities of the nurses in both wards were performed with poor working postures. In the orthopaedic (resp. urology) ward two (resp. one) out of 19 observed postures of parts of the body were classified as Action Category 2. Moreover, 20% (resp. 16%) of the so-called typical working postures was classified in Action Category 2. This suggests, that in both wards working postures that are slightly harmful to the musculoskeletal system, occur during a substantial part of the working day. Differences between both wards with respect to working posture load and time expenditure were determined. Activities causing the workload to fall into OWAS higher Action Categories were identified. The data show that poor working postures in the nursing profession not only occur during patient handling activities but also during tasks like ‘administration’. Focusing on patient-handling (i.e., lifting patients) in order to determine the load on the musculoskeletal system would therefore lead to an underestimation of the total working posture load of nurses     

The effects and measurement of working postures

Postures are a necessary result of undertaking working activities but the constraints the impose on these activities are not overtly recognised. The forms which these constraints can take are discussed, as well as the likely outcomes for a worker arising from long held or frequently adopted postures. Methods for the recording and evaluation of postures and their effects are described. Research into the relationships between the extent of and holding times for postures and the effects of various recovery times are discussed. Where a maximal postural effort has a recovery period of twelve times the length of the time the posture was held, only about 80% of the initial performance can be expected. Full recovery requires rest periods in excess of 1200% of working time.     

Effect of backpack load on the head,cervical spine and shoulder postures in children during gait termination

Twelve boys with an average age of 9.9 years were instructed to carry backpacks that weighed 0%, 10% and 15% of their body weights (BWs) to complete planned and unplanned gait termination experiments. The craniohorizontal, craniovertebral and sagittal shoulder posture angles at the sagittal plane as well as the anterior head alignment and coronal shoulder posture angles at the coronal plane were analysed. Results revealed significantly smaller craniohorizontal and sagittal shoulder posture angles during planned gait termination and a significantly smaller sagittal shoulder posture angle during unplanned gait termination under loaded conditions compared with those at 0% BW backpacks. Furthermore, the coronal shoulder posture angles at 10% and 15% BW during planned and unplanned gait terminations were significantly larger than those at 0% BW. Therefore, subjects were more likely to have a forward head posture, rounded shoulder posture and increased lateral tilting of the shoulders during gait termination as backpack loads were increased. However, gait termination, whether planned or unplanned, did not elicit a remarkable effect on posture.     

Baggage handling postures and the design of conveyors

The main purpose of this study was to determine the height, angle and velocity of conveyors for baggage handling at Schiphol Airport. These variables have a great influence on the postures and workload of baggage handlers. One hundred and seven healthy male baggage handlers participated in a test, during which a regular baggage handling task was simulated with a mock-up. Eighteen combinations of heights, angles and velocities were tested. Data on postures were collected with the aid of task recording and analysis on computer (TRAC). The minimal volume of open space under the conveyor was determined with light cells that scored the positions of legs and feet of the subjects. In addition, opinions from the baggage handlers were gathered with a questionnaire, immediately after the test. Finally the number of selection errors made and the number of bags that fell off the conveyor were noted, to make sure that ergonomics improvements did not reduce the quality of baggage handling. On the basis of these three information sources, alternative conveyor dimensions were recommended, which are expected to improve the working conditions of the baggage handlers, without any reduction in the quality of work.     

EMG analysis of sitting work postures in women

Based on EMG analysis on six middle-aged women, seven sitting work postures were compared with reference to relaxed standing position. The muscles included in the investigation are pectoralis major, levator scapulae, deltoideus, latissimus dorsi, upper fibres of the trapezius, erector spinae, vastus medialis and lateralis, rectus femoris and gastrocnemius muscles. The commoner sitting postures examined were sitting on the floor with crossed legs, sitting on the floor with right leg bent at the knee, sitting on the floor with left leg bent at the knee, squatting with both legs bent at the knee without any back support, sitting on a plank of 10 cm height with both legs bent at the knee, sitting on the floor with legs extended, and sitting upright on a stool of 40 cm height. The relative load on the muscles was highest in the case of sitting on the floor with the right leg bent at the knee. However, less muscle activity was noted when sitting on the floor with the legs extended, a posture commonly adopted by women performing various domestic and other activities.     

8- and 12-node plane hybrid stress-function elements immune to severely distorted mesh containing elements with concave shapes

By simply improving the first version of hybrid stress element method proposed by Pian, several 8- and 12-node plane quadrilateral elements, which are immune to severely distorted mesh containing elements with concave shapes, are successfully developed. Firstly, instead of the stresses, the stress function ? is regarded as the functional variable and introduced into the complementary energy functional. Then, the fundamental analytical solutions (in global Cartesian coordinates) of ? are taken as the trial functions for 2D finite element models, and meanwhile, the corresponding unknown stress-function constants are introduced. Thus, the resulting stress fields must be more reasonable because both the equilibrium and the compatibility relations can be satisfied. Thirdly, by using the principle of minimum complementary energy, these unknown stress-function constants can be expressed in terms of the displacements along element boundaries, which can be interpolated directly by the element nodal displacements. Finally, the complementary energy functional can be rewritten in terms of element nodal displacement vector, and thus, the element stiffness matrix of such hybrid stress-function (HS-F) element is obtained. This technique establishes a universal frame for developing reasonable hybrid stress elements based on the principle of minimum complementary energy. And the first hybrid stress element proposed by Pian is just a special case within this frame. Following above procedure, two 8-node and two 12-node quadrilateral plane elements are constructed by employing different fundamental analytical solutions of Airy stress function. Numerical results show that, the 8-node and 12-node models can produce the exact solutions for pure bending and linear bending problems, respectively, even the element shape degenerates into triangle and concave quadrangle. Furthermore, these elements do not possess any spurious zero energy mode and rotational frame dependence.     

8:12平衡调制码的设计与实现

在全息存储器中，数据页面通常要求审平衡的，即数据“0”和“1”的个数是相同的，解决该问题的一个有效办法就是采用平衡调制编码技术，根据这种要求，本文给出了一种8：12平衡调制码的编码原理和方法，该码字间的码距为4，因而具有纠错功能，采用本文介绍的方法，比简单的差分方法具有更高的编码效率，相应的编译码电路设计也不复杂，因而具有很强的实用性。     

不同年份的Radarsat与TM数据融合探测土地利用变更

常规的土地利用变更信息的遥感获取方式有分类后比较法和逐像元比较法/图像增强法。本文使用不同年份的遥感数据进行融合来探测土地利用变更信息,针对本文使用的雷达遥感数据的特点,本文采用改进的IHS变换法进行融合,对融合后图像的灰度进行分析,结果表明,融合图像的灰度既不同于融合前的Radarsat,又不同于融合前的TM,变更信息非常明显。     

Biomechanical aspects of occupational neck postures during dental work

A typical occupational risk factor for developing neck symptoms is prolonged flexion of the cervical spine. The present aim was to determine joint moments and muscle activity of the neck during forward flexion of the cervical spine to evaluate the load in the neck region. Three dimensional video (3-D) and surface electromyography (EMG) from the splenius muscles were recorded in two common work postures. Using a 3-D static link segment model, moments at the atlanto-occipital (A-O) joint and the seventh cervical-first thoracal (C7-T1) joint were estimated. Maximal extension moments were estimated from maximal neck extension strength. Extension moments at the C7-T1 joint were significantly higher for a highly flexed position (45% of max) compared to a moderately flexed position (32% of max), but remained unchanged at the A-O joint (40% of max). The mean RMS amplitude was 9% of maximal EMG in both positions (no bilateral differences). This difference between mechanical load and muscle load indicates that EMG may seriously underestimate the total loads of the tissue. Lateral flexion influenced the lateral flexion moment while rotation did not influence the rotation moment. The study demonstrates the importance of quantification of joint loads in occupational risk assessment of the neck.

Relevance to industry

3-D biomechanical calculations provide information on the mechanical load during work. Because EMG may underestimate total tissue load, calculations of joint moments in combination with information on muscle activity and strength are necessary to estimate different tissue loading of significance for overall risk identification.     

Motion study of the hip joint in extreme postures

Many causes can be at the origin of hip osteoarthritis (e.g., cam/pincer impingements), but the exact pathogenesis for idiopathic osteoarthritis has not yet been clearly delineated. The aim of the present work is to analyze the consequences of repetitive extreme hip motion on the labrum cartilage. Our hypothesis is that extreme movements can induce excessive labral deformations and lead to early arthritis. To verify this hypothesis, an optical motion capture system is used to estimate the kinematics of patient-specific hip joint, while soft tissue artifacts are reduced with an effective correction method. Subsequently, a physical simulation system is used during motion to compute accurate labral deformations and to assess the global pressure of the labrum, as well as any local pressure excess that may be physiologically damageable. Results show that peak contact pressures occur at extreme hip flexion/abduction and that the pressure distribution corresponds with radiologically observed damage zones in the labrum.

A comparison of different postures for scaffold end-frame disassembly

Overexertion and fall injuries comprise the largest category of nonfatal injuries among scaffold workers. This study was conducted to identify the most favourable scaffold end-frame disassembly techniques and evaluate the associated slip potential by measuring whole-body isometric strength capability and required coefficient of friction (RCOF) to reduce the incidence of injury. Forty-six male construction workers were used to study seven typical postures associated with scaffold end-frame disassembly. An analysis of variance (ANOVA) showed that the isometric forces (334.4-676.3 N) resulting from the seven postures were significantly different (p < 0.05). Three of the disassembly postures resulted in considerable biomechanical stress to workers. The symmetric front-lift method with hand locations at knuckle height would be the most favourable posture; at least 93% of the male construction worker population could handle the end frame with minimum overexertion risk. The static RCOF value resulting from this posture during the disassembly phase was less than 0.2, thus the likelihood of a slip should be low.