The prerequisites for electronic commerce are improving as well since

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A continuously increasing number of Germans do their work at the computer . The amount of the employed population that uses a PC in their job reached 60 percent for the first time . (German Association for Information Technology, Information, Telecommunications and new Media (BITKOM)) At 62 % , Germany is even significantly above the EU average of 50 % .

( Europäischen Statistikbehörde Eurostat ) Behind Germany are countries like the UK ( 49 % ) and Spain ( 48 % ) . cThe most recent developments are a good indicator for the technological modernization in Germany ; this applies equally to both economics and administration . d (BITKOM) The prerequisites for electronic commerce are improving as well since many workstation PCs are also connected to the internet .

In the past year the percentage of employees in this country that were able to use their computer to go online increased from 29 to 40 percent . During its investigation, the European statistical association Eurostat surveyed businesses that had at least ten employees . The banking sector was excluded .

Carpal Tunnel Syndrome The most important nerve in the hand, the Nervus Medianus , connects with all finger flexor tendons into a ... more. less.

type of tunnel that is formed through a cross - running band . The n . medianus provides the thumb, index and middle finger, as well as the portion of the ring finger toward the thumb, with sensation . In addition, the nerve has motor parts for the provision of thenar muscles . In the event of carpal tunnel syndrome, the n . medianus is constricted below this carpal band . Key symptoms include erroneous sensations (pins and needles, numbness) with fingers falling asleep from the thumb to the ring finger . Pain especially occurs during the night and in moments of rest . In the long term, carpal tunnel syndrome can develop into a repetitive strain injury (RSI) . Tissue changes and scar formations occur through the slightest injuries . These injuries first lead to symptoms and can be remedied through early treatment . The actual RSI develops with chronic damage and shows a chronic progression . The RSI symptoms particularly occur in humans that work with computers a great deal . Frequently (text processing, data entry) are most affected . In particular, repetitive motions, such as typing or mouse - clicks, are seen as being partially responsible for such injuries . The Screen Work Ordinance ( BildscharbV ) has been in power since late 1996 and legally regulates health protection during display work . In addition, it also makes the requirements of the labor protection law more concrete . With the help of this ordinance, the prevention of complaints and work - related illnesses can be realized within the company . Possible dangers for health and safety during display work are extensively taken into consideration, and mental as well as physical strains are taken into account . The ISO 9241 is an international standard whose guidelines describe the interaction between humans and computers . Since 2006 , the series of standards has the title cErgonomics of Human - System Interaction d, thus detaching itself from the previous title cErgonomic Demands for Office Tasks with Monitors d in order to dissolve prior focus on only office work . The series of standards consists of 17 parts assigned to the four areas of general guidelines, work environment, hardware and software . The goals of these are the avoidance of impairments to health during work with monitors and the facilitation of activities involving the computer display . The ISO 10075 standard deals with the ergonomic foundations regarding psychological work strain . The important aspects of the standard include psychological strains and demands, the design of tasks, technology, work environment, time and organization, and different measurement techniques and degrees of precision . The goals are the acquisition of convenient work conditions in relation to health, well - being and productivity, the reduction of psychological strain factors and the decrease of fatigue and feelings of monotony and stress, along with the avoidance of job strain . According to Schnurr ( 2007 ), one can distinguish between Stand - Sit - Dynamics and Sit - Stand - Dynamics . Sit - stand - dynamics describing the transition from sitting to standing, with the aim of avoiding unilateral loading of the spine by long sitting . The slide shows a systematic overview of important display technologies . The technologies can be divided into three categories : projection, direct view and off - screen Direct view displays : With these displays the light emitted from the device is seen directly on the monitor without first being reflected by a projection surface . All CRT, LCD, Plasma TV and computer monitors are direct view displays . These displays work best in bright light and have a greater light output than projection displays . Projection displays : Unlike direct systems, the projection display is based on the projection of an image onto the screen . There are frontal and rear projection systems which are significantly different in terms of screen technology . Frontal projection uses a reflective screen surface, whereas rear projection uses a transmitting surface . Projection displays work best in a dimly lit environment . Frontal projection in particular requires a darker room in order to reach optimal viewing quality . Off - screen displays : These display systems do not require any special projection surfaces . Instead, a natural medium such as glass or even the retina can be used for projection . Off - screen displays are based either on coherent or non - coherent light emission . Coherence is the ability of waves to generate stationary interference phenomena . Normally lasers have a much higher level of coherence than conventional light . VRDs (Virtual Retinal Displays) and 3 d holographic Head - up Displays are examples of off - screen display systems . TFT stands for Thin Film Transistor . This describes a set of planar circuit elements that actively control the individual picture elements . The display consists of a matrix with many pixels . Each of these pixels can transmit a predefined photoelectric light color . Usually several fluorescent tubes are used as a backlight behind the matrix . A picture is then created on the front of the elements as a kind of cshutter d is opened that allows the light for a specific pixel to be either transmitted or blocked . Thus, for electrically responsive liquid crystal are used in a specific layer, the so - called alignment layer (alignment shift) . There are two polarizing filter both in front and behind . The light is polarized by the first filter before entering into the alignment layer, i . e . the direction in which the light waves vibrate is fixed in a certain direction . Upon leaving the alignment layer there is another filter which is turned 90 ° . The following filter transmits light waves that are also turned in the same direction . In a de - energized state, the liquid crystal alignment layer rotates the vibration direction of the of the light by 90 ° so that the light can pass freely (twist) . It is necessary to present the information on the screen at a size and quality that is easy to recognize . For characters that appear at an angle of vision between 22 e and 31 e, this demand is fulfilled . An angle of vision of at least 22 e is given when the height of capital letters, without ascender (character height), is equal to the designated viewing distance divided by 155 . However, the font height should also not be greater than the viewing distance divided by 110 , because fluid reading then becomes more difficult (font height of approximately 4 . 5 mm at the most at a viewing distance of 500 mm, corresponding to an angle of vision of 31 e at the most) . At a viewing distance of 500 mm, font heights of 3 . 0 to 4 . 0 mm should be strived for . For text processing, it is also necessary for at least 80 characters per line can be shown . To investigate the age related coherence between acuity of vision and human performance, a symbol detection task was conducted on the basis of three different font sizes ( 16 f, 20 f and 22 f arc minutes) . Results from partial correlation analysis point to an age differentiated adaption of font size rather than an adaption based on a measurement of visual acuity . The number of symbols to be detected and the response times of correct responses were analyzed with an analysis of variance . The results were derived from data of 75 subjects between 20 and 75 years, and they show a strong effect of font size and a medium age related effect . Results revealed that regardless of participants f age, the best performance in terms of short response time occurs with the biggest font size of 22 f arc minutes . The possibility to compensate age related differences in response time by enlarging the font size from 16 f arc minutes up to 22 f arc minutes supports the approach of age differentiated adaption of the human computer interface . Dependence of light density of visual direction : An anisotropic display is referred to as one in which the light density for the visual situation decreases diagonally to the picture level by more than 10 % in comparison to the normal viewing position (ISO 13406 - 2 2003 ) . Experiment for recognition performance with TFT displays The goal of Ziefle es study ( 2004 ) was to examine the influence of a TFT display es anisotropy on the recognition performance of young adults . To do so, a TFT display was compared with a CRT display . Subjects had to process a visual search task in which objects (similar to Landoltrings) were presented to them . Then, the subjects had to decide whether each object was opened on the top, bottom, right or left . The recognition time for both displays increases with an increase in the viewing angle due to the negative effects of anisotropy . However, the recognition times in the statistical middle are greater for the TFT display and the negative anisotropy effect is stronger for smaller targets . Experimental studies on dual monitor configuration . The subjects f task consisted of discriminating ZiSo fs (similar to Landolt rings, but square) . Study 1 : Comparison of horizontal dual monitor configuration (two versus one monitor) The simultaneous monitoring of multiple monitors arranged horizontally (each 50 ° left and right from the viewer) in comparison to working with only one monitor was analyzed . The recognition of targets on one screen results in significantly faster processing than the recognition of targets in two horizontally aligned monitors . There are no significant differences regarding the processing accuracy . Study 2 : Comparison of vertical dual monitor arrangement (arranged above or below) The influence of the viewing angle is detected by the comparison between the upper and lower screen position . The assignment given to the subjects was solved significantly faster when using the lower screen, as compared to the upper screen . The viewing angle had no influence on the processing accuracy . Study 3 : The influence of the screen location (right or left of the viewer) The visual activity caused by stimulating displays was investigated for the left versus right monitor . Independent from the screen technology, the right - handed monitor achieved shorter reaction times . There were however no differences in the processing accuracy . When an eye focuses on an object (e . g . , A in the left image), then the images fall onto the corresponding points on the retina (points a 1 and a 2 ) . A further away (or closer) object (B) creates images across from the corresponding shifted retina places (disparities), points (point b 1 and b 2 ) . The sideways offset is called disparity . In the right image, a presentation of a wire die is depicted on both eyes . A spatial impression is created in the visual center from the image differences . It is important to note that the images in the eye are always presented as inverted due to the lens system . A conversion to the cactual d image occurs cognitively . Lateral disparity refers to the difference of the images on the right and left retina that occurs through the interocular distance (approximately 6 . 5 cm for humans) . The visual system has the ability to acquire information for spatial vision from the difference of these two - dimensional images . The result is termed stereoscopic vision . Differentiation between crossed lateral disparity and uncrossed lateral disparity occurs . Crossed lateral disparity occurs when objects lie in front of the horopter , thereby falling on the outer edge of the retina : Point B is displayed left of the fovea in the left eye and right of the fovea in the right eye . Uncrossed lateral disparity refers to when objects lie behind the horopter , thereby falling on the inner edge of the retina : Point C is displayed right of the fovea in the left eye and left of the fovea in the right eye . The theoretical point horopter is shown by the total points that are displayed on the corresponding areas of the retinas of both eyes during a fixed eye position . Points/objects that lie on the surface of the horopter or close to it are easily recognized (fused) ; those in front of or behind are seen as doubled . These doubled images are usually suppressed . During artificial stereoscopy, the observer is shown two pictures of varying visual positions . The natural viewing of different pictures with two eyes is thus reproduced . The different techniques of stereoscopic presentation therefore also have either two separate image areas or else function in a time - division manner . If photos are shown to the observer, the camera distance and angle must already be taken into consideration during photographing . The distance of virtual cameras, the angle of the cameras and the perspective of the generated pictures can be determined for the display of 3 D scenes that are first calculated by the computer . The display of two different pictures is inherent to all stereoscopic display systems . The first systems, so - called stereoscopes, were already around in the 18 th century . Two photographs were required from two different lines of vision . The observer was able to view the stereoscopic half - images with the stereoscope . In this case, the left half - image was presented to the left eye, and the right half - image to the right eye . A cognitively created impression of depth then occurs through the merge of the two half - images . Today fs stereoscopic monitors function in a similar way . The key difference is that the pictures are not static photographs, but rather images on the display . Even haploscopic division, i . e . , the transmission of each half - image to the eyes, occurs differently with sterescopic monitors than for the historic stereoscopes . Currently, and aside from separate displays on two monitors, e . g . , through mirror systems or HMDs (head mounted displays), haploscopic division can also be carried out through multiplex procedures . Thus, shutter glasses show the left and right eye a temporally alternating monitor image while autostereoscopic monitors present the left and right eye with a spatially alternating image . The principle of alternating half - image presentation can be seen on the left side of the figure . The images for the left and right eye are already interlinked in the computer by graphics card drivers so that only the interlinked image is then transferred to the monitor . The prism masks mode of operation is presented on the right side of the figure . The prisms are laid out in such a way that the alternating pixel gaps are diverted to both the left and right eye . If the eyes of the observer are within the so - called Sweet Spot, i . e . , within the region to which the light is diverted, then each eye receives the image specific to that eye, and a spatial impression is created . However, information is lost during the interlinking of the left and right half - image . Basically, the horizontal resolution of the images is halved . This leads to distorted edges, particularly for text . A decrease in depth resolution also occurs for spatial perception due to the halving of the horizontal resolution . In principle, volumetric displays are able to blur the boundaries between illusion and reality 3 the observer cdives into d the picture . Currently, there are various possibilities for producing a three - dimensional accurate visual impression . Perspecta 198 individual two - dimensional images come together within a half - sphere made of glass to create a three - dimensional image . These individual images are projected onto a plastic disc rotating transparency screen within the sphere by a projector that produces 5000 frames per second . The human eye then sees the image as being three - dimensional . In contrast to conventional procedures, for Perspecta the observer does not require 3 D glasses and is not limited to one specific visual angle . DepthCube A beamer projects a color image onto back - to - back layered glass plates . The basic material consists of 20 normal TFT display panels that now function only as individual matt screens . Only one of the plates serves as a matt screen while the other 19 allow light to pass through . The 3 D image is formed plate - wise, always on a different TFT panel . A spatial depth of approximately 10 centimeters is formed by 20 back - to - back panels . The monitor serves as the cviewing frustum d . A high - performance beamer delivers the image on digital light processing (DLP) basis with an output of approximately 800 Watts . The output must be that great because TFT panels only allow a small amount of light to pass through . Only the beamer is responsible for the color . A special algorithm for the smoothing of edges ensures that no transitions can be seen in the 3 D range . DepthCube A color image from a projector is projected onto consecutively staggered glass panels . The basic material uses 20 standard TFT display panels, which now acts as a single screen . 19 of the layers are translucent, and only one acts as the opaque layer . The 3 D image is then built up in layers, always on a different LCD panel . 20 of these successive panels results in a spatial depth of about ten centimeters . The monitor serves as a quasi cvisual body d . The image requires a very powerful projector of the Digital Light Processing (DLP) type, with a capacity of about 800 watts . The large amount of power is needed because the TFT panels only allow low levels of light through . The projector is responsible for the colors . In order to avoid visible transitions between the individual panes, a special algorithm provides for antialiasing in 3 D applications . Age differentiated study of different input devices . With the three different input devices (mouse, touch screen, eye gaze input) the 90 test subjects between 20 and 75 years have to conduct a two dimensional pointing task . The execution time as well as the mental workload were measured as dependent variables . Following a direct comparison of the three input devices, it must be emphasized that, regardless of participants f age, the best performance in terms of short execution time results from touch screen information input . Surprisingly mouse input showed the poorest average performance among all subjects . However, the effect of the execution time improvement through alternative input devices (touch screen, eye - gaze) varies in strength among the different age groups . The greatest improvement in performance can be achieved by the 60 to 75 year - olds . These participants need on average twice as long as the 20 to 39 year - olds for information input with the mouse . However, when using a touch screen they reach a performance level similar to that of younger people using a mouse . The illuminance ( Lux = Lumen/square meter) corresponds to the relationship of light hitting a certain surface (usually the workspace) to the size of this surface . If a luminous flux of 1 Lumen hits a 1 m 2 surface then the illuminance is of 1 Lux (lx) . The luminous flux decreases with punctiform light sources with a square of distance between light source and evaluated surface . The reflectance is the relationship of the reflected luminous flux to that hitting the surface . Reflectance reproduces the characteristics of surfaces in order to reflect the light beams appearing . Luminous flux and illumination are known as the radiance emitted from a light source, both generally in all directions (luminous flux) as well as in a specific area (illumination) . A particular topic of interest is luminance which lights up a particular surface ; the measure of illuminance is used in this case . For radial symmetric bodies with perpendicular occurrence of radiance the following holds true Ev = Iv / r², when r expresses the distance between the radiating and the receiving body . Thus, illuminance can be varied quite easily through a change in distance . The luminous intensity (Candela) is the visible radiation from a light source in a particular solid angle, and belongs to the SI base units . The solid angle ( Steradiant ) is the measurement for the size of the cone - shaped or pyramid - shaped region that contain beams of light . It can be calculated from the relationship between the perpendicularly lit surface to the square of the distance between the surface and the beam fs point of origin : = F/r 2 . Illuminance " The luminous flux density at a surface, i . e . the luminous flux incident per unit area " Quotient of the luminous flux by the area of the surface when the latter is evenly illuminated " The illuminance at an area is 1 Lux (lx), if a luminous flux of 1 lumen (lm) falls perpendicularly onto an area of 1 m 2 " Independent of the reflectance of an illuminated surface " The most frequently used quantity in illumination engineering " Recipient - related quantity Luminous intensity " Luminous flux emitted per solid angle unit to a specific direction " Direction dependent, independent of recipient quantity " Sender - related quantity Luminance " Luminous intensity of a light source in relation to the emitting area of the emitter (light source or reflecting area) " Subjective quantity to the brightness sensitivity, only perceivable to the human being " Sender - related quantity Adaptation : The adaptation of the eye to luminance in the field of view occurs through photochemical and physiological adaptation of the retina as well as a change in the pupil opening . This ability of the eye is called Adaptation and greatly influences several sight functions . The time needed for this adaptation heavily depends on luminance at the beginning and at the end of the adaptation . A shift from light to dark is known as dark adaptation ; the opposite is known as light adaptation . [Illustration above : Schematic process of dark adaptation with an initial value of 100 cd /m²] Accommodation : Accommodation is known as the ability of the eye to focus on an object at a certain distance . This is done through an increase or decrease in the radius of curvature of the eye lens . The formability of the lens decreases over the course of a person fs life, also resulting in a decrease in the range of accommodation . The speed of accommodation also decreases quite quickly with an increase in age . [Illustration in center : Range of accommodation (Range of visual acuity : from nearest point to infinity) of the eye dependent on age] Visual acuity : Visual acuity indicates the ability to recognize small objects, and is expressed as the reciprocal value of the smallest angle (in arc minutes) from which the eye can directly perceive a detail (object) . This measure of visual acuity is called visus . Visual acuity is influenced by a variety of factors, such as age, luminance, accommodation, contrast and color of light .

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