New fossils reveal the hand of Paranthropus boisei.

OCCUPATIONAL APPLICATIONS Powered hand tools are widely used during assembly operations. The hand displacement during powered hand-tool use has been identified as a potential risk factor for upper extremity musculoskeletal disorders. In the current study, the mechanical properties of the upper extremity were identified, which represent muscle capacity to react to an impulsive power tool torque loading and affect the responsive hand displacement. These properties were obtained from among experienced and inexperienced participants under various operating configurations, including working heights, horizontal working distances, tool moments of inertia, and joint type. The results indicated that operating configurations and experiences affected the mechanical properties of upper extremities in different ways. This research may help in future studies on powered hand-tool work-station design, for example by improving parameters in biomechanical models.TECHNICAL ABSTRACT Rationale: Hand-tool displacement during powered hand-tool use is a potential risk factor for upper extremity injuries and is correlated to the subjective discomfort level. The upper extremity has been modeled as a second-order linear system to describe the hand-tool response. While previous studies have found that working environment factors and operator experience significantly affect the hand-tool response during powered tool use, how those factors affect the mechanical properties of the upper extremity has not been investigated. Purpose: This study assessed the mechanical properties of the upper extremity under various working environment factors and operator experience levels. Method: A least-squares method was used to identify the mechanical properties of the upper extremity during powered hand-tool use, directly from the dynamics of hand-tool response. Results: Working heights, horizontal working distances, hand tool moments of inertia, joint type, and experience significantly affected some mechanical properties of the upper extremities in various operating configurations. In addition, stiffness and damping coefficients of the upper extremities were greater than those values identified from a free oscillation system in a previous study. Conclusions: Mechanical properties of the upper extremities can be used to predict hand displacement during powered hand-tool use. The current results provide additional information to improve the understanding of operator reactions to powered hand tools.

There is an increasing trend to develop innovative information technologies that empower industrial companies and tool suppliers to pioneer new production methods and technologies. This study aims to support innovation in industrial practices by using information technologies to enable companies and tool suppliers to adopt advanced production methods. By focusing on the usability of hand tools, the research seeks to establish essential parameters and focuses on analyzing the perception of risk and its associated benefits when using hand tools. To examine risk perception and risk benefits when using hand tools, the analysis data were collected from workers in two countries and included studies processed by Domain-Specific Risk-Taking (DOSPERT). As a result, it is identified as risk-seeking in the sphere of workers who are very confident in their ability and capacity to perform the determined tasks and carry out risk aversion with other external parameters related to hand tools and environmental characteristics. In addition, the risk perception and worker behavior to deal with it are delineated, giving parameters to help managers avoid workers’ injuries or illnesses, identifying the main risk domains for using hand tools use in specific industrial tasks.

The human tool operator was modeled as a one degree of freedom mechanical torsion system in order to predict human capacity to react against large non-harmonic forces. Such a practical model can be used to design better hand tools and industrial tasks that minimize the risk of upper limb disorders by predicting the kinetic and kinematic responses of the body to impulsive torques in hand tool use for a given population. A standing operator grasping a tool handle was therefore mechanically represented as mass, spring and damper elements. The values of these elements were dependent upon body posture and the individual operator. The apparatus used to quantify the model parameters measured the response change of a known mechanical system by the external loading of the hand and arm during free vibration frequency and amplitude decay. Twenty-five subjects were tested in a repeated measures experiment for factors representative of actual workplace conditions including hand horizontal location, hand vertical location, handle shape and tool orientation.

A research project that is sponsored by the Bureau of Mines, Department of Interior and conducted by Ohio State University is analyzing the accidents caused by hand tools used in the underground coal, metal, and nonmetal mining industries. To describe the accident types and the resulting injuries, a thorough search was conducted of a computer data base of mining-related accidents. After sorting for data pertaining to hand tools, analyses were carried out to determine likely scenarios, and their probability of occurrence, for the various hand tool injuries. This project, which summarized accident data for a six-year period, is the first comprehensive evaluation of hand tool accident data related to underground mining. The method of accident classification, which is based on accident type, part of body injured, and nature of the injury, allows assessment of the key components of the hand tool injury. Furthermore, this analysis, in conjunction with the scenario development, provides direction for future research into hand tool ergonomics.

Effectiveness of a handle flange for reducing manual effort during hand tool use

Pantomiming tool use with an imaginary tool in hand as compared to demonstration with tool in hand specifically modulates the left middle and superior temporal gyri

The purpose of this study was to determine the prevalence and incidence of trigger finger (TF) in a meat-packing plant and explore the relationship between hand-tool use and the development of TF. A cross-sectional study was competed wherein 665 workers were interviewed and examined to determine the point prevalence. Subsequently, 454 TF-negative workers were followed up and examined twice at a median interval of 225 days. The point prevalence of TF was 14%. The person-year incidence rate was 12.4% and 2.6% for tool use and non-tool use workers, respectively. Forty-three cases of TF (75.2%) in the incidence arm of the study used a hand tool, for a relative risk of 4.7 (P < 0.002; 95% confidence interval, 1.5-23.9). Although a significant relationship was found between ethnicity and the presence of TF in the prevalence data, this was not confirmed in the incidence study. There is an increased prevalence of TF in this meat-packing plant and high worker turnover may underestimate the true prevalence rates. Hand-tool use increases the risk of developing TF.

Trabecular bone patterning across the human hand

Some forms of canine cognition research require a dispenser that can accurately dispense precise quantities of treats. When using off-the-shelf or retrofitted dispensers, there is no guarantee that a precise number of treats will be dispensed. Often, they will over-dispense treats, which may not be acceptable for some tasks. Here we describe a 3D-printed precise treat dispenser with a 59-treat capacity driven by a stepper motor drive and controlled by an integrated Raspberry Pi. The dispenser can be built for less than 200 USD and is fully 3D printable. While off-the-shelf dispensers can result in an error rate of 20–30%, the precision dispenser produces a 4% error rate. This lower error rate and the integrated Raspberry Pi allows for new possibilities for using treat dispensers across a range of canine research questions. <strong>Metadata Overview</strong> Main design files: <a href="https://github.com/unl-cchil/canine_precise_dispenser" target="_blank"><em>https://github.com/unl-cchil/canine_precise_dispenser</em></a> Target group: Scientists in canine cognition. Skills required: desktop 3d printing – easy; through-hole soldering – easy; hand tool use – easy Replication: No builds known to the authors so far. <em>See section “Build Details” for more detail</em>.

A system for the measurement of grip forces and applied moments during hand tool use

Comparison of comfort, discomfort, and continuum ratings of force levels and hand regions during gripping exertions

The effects of tool handle shape on hand performance, usability and discomfort using masons' trowels

Hand function and tool behavior in early hominids.

Design and performance of a manual task evaluator

Modern humans are characterized by specialized hand morphology that is associated with advanced manipulative skills. Thus, there is important debate in paleoanthropology about the possible cause–effect relationship of this modern human-like (MHL) hand anatomy, its associated grips and the invention and use of stone tools by early hominins. Here we describe and analyse Olduvai Hominin (OH) 86, a manual proximal phalanx from the recently discovered >1.84-million-year-old (Ma) Philip Tobias Korongo (PTK) site at Olduvai Gorge (Tanzania). OH 86 represents the earliest MHL hand bone in the fossil record, of a size and shape that differs not only from all australopiths, but also from the phalangeal bones of the penecontemporaneous and geographically proximate OH 7 partial hand skeleton (part of the Homo habilis holotype). The discovery of OH 86 suggests that a hominin with a more MHL postcranium co-existed with Paranthropus boisei and Homo habilis at Olduvai during Bed I times.