108,212 research outputs found
A 2.5-D representation of the human hand
Full text linkPrimary somatosensory maps in the brain represent the body as a discontinuous, fragmented set of 2-D skin regions. We nevertheless experience our body as a coherent 3-D volumetric object. The links between these different aspects of body representation, however, remain poorly understood. Perceiving the body’s location in external space requires that immediate afferent signals from the periphery be combined with stored representations of body size and shape. At least for the back of the hand, this body representation is massively distorted, in a highly stereotyped manner. Here we test whether a common pattern of distortions applies to the entire hand as a 3-D object, or whether each 2-D skin surface has its own characteristic pattern of distortion. Participants judged the location in external space of landmark points on the dorsal and palmar surfaces of the hand. By analyzing the internal configuration of judgments, we produced implicit maps of each skin surface. Qualitatively similar distortions were observed in both cases. The distortions were correlated across participants, suggesting that the two surfaces are bound into a common underlying representation. The magnitude of distortion, however, was substantially smaller on the palmar surface, suggesting that this binding is incomplete. The implicit representation of the human hand may be a hybrid, intermediate between a 2-D representation of individual skin surfaces and a 3-D representation of the hand as a volumetric object
Thick-film force, slip and temperature sensors for a prosthetic hand
No full textThick-film static and dynamic force sensors have been investigated for their suitability to measure the grip forces exerted upon an object held by a prosthetic hand, and to detect and correspondingly react to the possible slip of a gripped item. The static force sensors exploit the piezoresistive characteristics of commercially available thick-film pastes whilst the dynamic slip sensors utilise the piezoelectric behaviour of proprietary PZT pastes (lead zirconate titanate). The sensors are located upon stainless steel cantilever type structures that will be placed at the fingertips of each digit of the prosthetic hand. Temperature sensors are also included to provide temperature compensation for the force sensors and to prevent accidental thermal damage to the prosthesis. Results have shown that the static force sensor is capable of measuring fingertip forces in excess of 100 N, with an electrical half-bridge configuration sensitivity approaching 10 ?V/V•N (with scope for improvement) and maximum hysteresis below 4% of full scale, depending on the manner by which the cantilever sensor array is attached to the finger. Failure in the bonding mechanism that secures the PZT layer to the stainless steel cantilever meant that the proposed dynamic force sensor could not be evaluated. However, investigations using the same sensor design fabricated on an alumina substrate have shown the potential of the PZT dynamic force sensor to measure vibration and hence potentially operate as a slip sensor
The effectiveness of origami on overall hand function after injury: A pilot controlled trial
No full textThis pilot study measured the effectiveness of using origami to improve the overall hand function of outpatients attending an NHS hand injury unit. The initiative came from one of the authors who had used origami informally in the clinical setting and observed beneficial effects. These observed effects were tested experimentally. The design was a pilot non-randomised controlled trial with 13 participants. Allocation of the seven control group members was based on patient preference. The experimental group members attended a weekly hour of origami for six weeks, in addition to their conventional rehabilitation.
Hand function of all participants was measured using the Jebsen-Taylor Hand Function Test before and after the six-week period, and additional qualitative data were gathered in the form of written evaluations from patients. The quantitative data were analysed using the Mann Whitney U test or Fisher’s exact test. Themes were highlighted from the qualitative data.
The results show that there was a greater difference in the total score of the experimental group using the impaired hand between pre- and post-intervention of 11.8 seconds, compared with 4.3 seconds in the control group, but this was not statistically significant at the 5% level (p=0.06). Additionally, differences in the sub-test scores show a markedly larger improvement in the experimental group. Qualitative data indicate that the experimental group experienced the origami sessions as being enjoyable and beneficial. Further research with a larger sample and randomised group allocation is recommended to verify and expand these preliminary findings
Risks of occupational exposures to hand-transmitted vibration: VIBRISKS
No full textVIBRISKS seeks to improve understanding of the risk of injury from hand-transmitted vibration and whole-body vibration by means of epidemiological studies supported by fundamental laboratory
research. VIBRISKS is a consortium of six partners from six European countries (France, Germany, Italy, Sweden, The Netherlands, UK). The four-year research project, which commenced in 2003, involves three work packages devoted to hand-transmitted vibration and three work packages devoted to whole-body vibration. This paper summarizes the hand-transmitted vibration research. Work package 1 defines methods to be used in studies of disorders caused by hand-transmitted
vibration in work package 2 and integrates the results of the epidemiological studies in work package 2 with the results of experimental and modeling studies in WP3 so as to define procedures that can be applied by occupational health workers for minimizing risk, screening exposed individuals and managing individuals with symptoms. Work package 2 involves longitudinal studies in workers
exposed to hand-transmitted vibration. Work package 3 involves experimental studies of the acute effects of hand-transmitted vibration on vascular and neurological function and the development of a finite element model of the biodynamic responses of the finger to vibration and force
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Definition of antigenic heterogeneity and modulation among human mammary carcinoma cell populations using monoclonal antibodies to tumor associated antigens
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The Relationship of Hand Grip Strength with Bone Mineral Density and Vitamin D in Postmenopausal Women
No full textObjective: The aim of the present study was to evaluate the relationship of hand grip strength (HGS) with bone mineral density (BMD) and
vitamin D levels in postmenopausal women.
Materials and Methods: One hundred thirty one postmenopausal women were included in this study. HGS was measured by Jamar hand
dynamometer. BMD was measured by dual energy X-ray absorptiometry at lumbar spine and femoral neck sites. Serum 25-hydroxyvitamin
D (25OHD) levels were measured.
Results: The mean age of patients was 61.2±9.2 years. The mean HGS was 22.9 kg and 32 patients (24.4%) had low HGS. Thirty seven
patients (28.2%) were osteoporotic and 62 (47.3%) were osteopenic. The mean 25OHD level was 17 ng/mL and 101 (77.1%) patients
having vitamin D insufficiency. There was a significant difference in HGS values among groups with osteoporosis, osteopenia, and normal
BMD (p=0.016). HGS values demonstrated a positive correlation with T-scores and BMD values at lumbar spine and femoral neck sites
(p<0.001, r=0.340; p<0.001, r=0.300; p<0.001, r=0.320; p=0.001, r=0.298, respectively) and negative correlation with age and duration of
menopause (p<0.001, r=-0.344; p<0.001, r=-0.318; respectively). However, no significant association was observed between 25OHD levels
and HGS (p=0.860, r=0.016).
Conclusion: Postmenopausal women with osteoporosis had lower HGS than postmenopausal women with normal BMD, and HGS was
significantly correlated with BMD, but not with vitamin D in this population. The patients should be encouraged to increase muscle strength
for the risk management of osteoporosis in postmenopausal wome
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