Identifying the Ergonomic Risk Factors of a Job

[Excerpt] When we experience overexertion of muscles and joints, common symptoms include soreness, pain, discomfort, redness and swelling, limited range of motion, stiffness in joints, weakness and clumsiness, numbing/ tingling sensations (“pins and needles”), popping and cracking noises in the joints, and “burning” sensations in muscles. We need to pay attention to these warnings and act quickly to prevent trauma from becoming more serious. For repetitive jobs, over time, cumulative trauma injuries can develop. At first, our symptoms of pain and/or weakness are felt during work and disappear during off-hours or rest. Usually the body recovers and the problem is completely reversible at this stage. But, if the workplace conditions of the task are not changed, the injury can progress to the point that our symptoms no longer disappear completely between work shifts. This means that our bodies are unable to completely repair the affected tissues during rest. We may find that our symptoms are beginning to interfere with our ability to perform our usual work activities. We might find that we are moving more slowly, taking care how we bend or reach, conserving our movements just to get through the day. But, if the work conditions are still not changed and the trauma is allowed to continue, we may find that the pain persists even at rest, even to the point that we have trouble sleeping. At this stage, severe pain, limited mobility, loss of sensation or muscle weakness can make it impossible to perform most tasks. We find both our work and our home life affected – brushing teeth, combing hair, picking up objects, getting up and down on the toilet – everyday life is impacted

Transition to chaos and escape phenomenon in two degrees of freedom oscillator with a kinematic excitation

We study the dynamics of a two-degrees-of-freedom (two DOF) nonlinear oscillator representing a quartercar model excited by a road roughness profile. Modelling the road profile by means of a harmonic function we derive the Melnikov criterion for a system transition to chaos or escape. The analytically obtained estimations are confirmed by numerical simulations. To analyze the transient vibrations we used recurrences.Comment: 13 pages, 16 figures, in pres

Color and texture associations in voice-induced synesthesia

Voice-induced synesthesia, a form of synesthesia in which synesthetic perceptions are induced by the sounds of people's voices, appears to be relatively rare and has not been systematically studied. In this study we investigated the synesthetic color and visual texture perceptions experienced in response to different types of “voice quality” (e.g., nasal, whisper, falsetto). Experiences of three different groups—self-reported voice synesthetes, phoneticians, and controls—were compared using both qualitative and quantitative analysis in a study conducted online. Whilst, in the qualitative analysis, synesthetes used more color and texture terms to describe voices than either phoneticians or controls, only weak differences, and many similarities, between groups were found in the quantitative analysis. Notable consistent results between groups were the matching of higher speech fundamental frequencies with lighter and redder colors, the matching of “whispery” voices with smoke-like textures, and the matching of “harsh” and “creaky” voices with textures resembling dry cracked soil. These data are discussed in the light of current thinking about definitions and categorizations of synesthesia, especially in cases where individuals apparently have a range of different synesthetic inducers

An analytical stability theory for Faraday waves and the observation of the harmonic surface response

We present an analytical stability theory for the onset of the Faraday instability, applying over a wide frequency range between shallow water gravity and deep water capillary waves. For sufficiently thin fluid layers the surface is predicted to occur in harmonic rather than subharmonic resonance with the forcing. An experimental confirmation of this result is given. PACS: 47.20.Ma, 47.20.Gv, 47.15.CbComment: 10 pages (LaTeX-file), 3 figures (Postscript) Submitted for publicatio

Emotional Prosody Measurement (EPM): A voice-based evaluation method for psychological therapy effectiveness

The voice embodies three sources of information: speech, the identity, and the emotional state of the speaker (i.e., emotional prosody). The latter feature is resembled by the variability of the F0 (also named fundamental frequency of pitch) (SD F0). To extract this feature, Emotional Prosody Measurement (EPM) was developed, which consists of 1) speech recording, 2) removal of speckle noise, 3) a Fourier Transform to extract the F0-signal, and 4) the determination of SD F0. After a pilot study in which six participants mimicked emotions by their voice, the core experiment was conducted to see whether EPM is successful. Twenty-five patients suffering from a panic disorder with agoraphobia participated. Two methods (storytelling and reliving) were used to trigger anxiety and were compared with comparable but more relaxed conditions. This resulted in a unique database of speech samples that was used to compare the EPM with the Subjective Unit of Distress to validate it as measure for anxiety/stress. The experimental manipulation of anxiety proved to be successful and EPM proved to be a successful evaluation method for psychological therapy effectiveness

Fluorescence for high school students

In a not obligatory series of lessons for high school students in the Netherlands we discuss the fluorescence aspects of anthracene. These lessons were developed because HiSPARC (High school Project on Astrophysics Research with Cosmics) detection of cosmic rays are available for different secondary schools. With the help of special designed scintillator detection stations, containing anthracene, cosmic rays can be detected. Fluorescence of anthracene is one of the topics discussed in these series of extra curricular lessons aimed at excellent pupils working on cosmic radiation within the HiSPARC - project.Comment: 14 pages, 13 figures, 5 reference