Search

Approximately 2% of the German population suffer from psoriasis. HybridVITA has developed a mobile application (app) that enables psoriasis patients to independently document the progression of the disease and the current psychological stress at home. The HybridVITA app was created in close collaboration with user groups to ensure optimal adaptation to their needs. Two interactive workshops were held with the user groups and the technical developers of the app as a core element of the developmental process. The workshops identified the needs and suggestions for improvement of the various user groups and formulated user stories for the further development of the app using the Scrum method. The participatory approach of the workshop enabled the project team to gather valuable practical knowledge at an early stage of development. The team's awareness of potential obstacles during the early stages of the project enabled them to proactively identify and address these issues prior to implementing the app in dermatological care. We are confident that a patient-centered and participatory approach to health app development can provide valuable insights for developers., (© 2024. The Author(s).)

Significance: The database for multipulse retinal damage thresholds for the laser safety standard (IEC 60825-1:2014) is confined, especially for elongated irradiation profiles. To ensure eye safety, retinal damage thresholds ( ED 50 values) need to be determined., Aim: This study aims to examine nanosecond multipulse scenarios., Approach: To determine ED 50 values in ex vivo measurements, an optical laser setup is presented. Porcine explant tissue is irradiated with rectangular top-hat profiles. Thermal simulations are carried out on a validated computer model and retinal injury thresholds are obtained., Results: The measurements resulted in ED 50 values from 8.46 to 42.72    μ J with a slope from 1.15 to 1.4. A thermal damage in the measurements can be excluded due to the level value in combination with a different type of declining behavior for increasing pulses compared to the simulations. A dependence with increasing elongation or area of the retinal image emerges in the simulations but could not be confirmed in the measurements due to the influencing factors (biological variability, focusing, and measuring procedure)., Conclusions: Using slit apertures for beam shaping, variable rectangular spot geometries are realized without changing elements in the setup. For further evaluation of the behavior of elongated irradiation profiles, additional measurements to improve the measurement accuracy are necessary., (© 2023 The Authors.)

Heart rate variability (HRV) is an important indicator of autonomic nervous system activity and can be used for the identification of affective states. The development of remote Photoplethysmography (rPPG) technology has made it possible to measure pulse rate variability (PRV) using a camera without any sensor-skin contact, which is highly correlated to HRV, thus, enabling contactless assessment of emotional states. In this study, we employed ten machine learning techniques to identify emotions using camera-based PRV features. Our experimental results show that the best classification model achieved a coordination correlation coefficient of 0.34 for value recognition and 0.36 for arousal recognition. The rPPG-based measurement has demonstrated promising results in detecting HAHV (high-arousal high-valence) emotions with high accuracy. Furthermore, for emotions with less noticeable variations, such as sadness, the rPPG-based measure outperformed the baseline deep network for facial expression analysis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Most types of dementia, including Alzheimer's disease, are not curable. However, there are risk factors, such as obesity or hypertension, that can promote the development of dementia. Holistic treatment of these risk factors can prevent the onset of dementia or delay it in its early stages. To support individualized treatment of risk factors in dementia, this paper presents a model-driven digital platform. It enables monitoring of biomarkers using smart devices from the internet of medical things (IoMT) for the target group. The collected data from such devices can be used to optimize and adjust treatment in a patient in the loop manner. To this end, providers such as Google Fit and Withings have been connected to the platform as example data sources. To achieve treatment and monitoring data interoperability with existing medical systems, internationally accepted standards such as FHIR are used. The configuration and control of the personalized treatment processes are achieved using a self-developed domain-specific language. For this language, an associated diagram editor was implemented, which allows the management of the treatment processes through graphical models. This graphical representation should help treatment providers to understand and manage these processes more easily. To investigate this hypothesis, a usability study was conducted with twelve participants. We were able to show that such graphical representations provide advantages in clarity in reviewing the system, but lack in easy set-up (compared to wizard-style systems).

Background: Age-related diseases such as dementia are playing an increasingly important role in global population development. Thus, prevention, diagnostics, and interventions require more accessibility, which can be realized through digital health apps. With the app on prescription, Germany made history by being the first country worldwide to offer physicians the possibility to prescribe and reimburse digital health apps as of the end of the year 2020., Objective: Considering the lack of knowledge about correlations with the likelihood of use among physicians, this study aimed to address the question of what makes the use of a digital health app by physicians more likely., Methods: We developed and validated a novel measurement tool-the Digital Health Compliance Questionnaire (DHCQ)-in an interdisciplinary collaboration of experts to assess the role of proposed factors in the likelihood of using a health app. Therefore, a web-based survey was conducted to evaluate the likelihood of using a digital app called DemPredict to screen for Alzheimer dementia. Within this survey, 5 latent dimensions (acceptance, attitude toward technology, technology experience, payment for time of use, and effort of collection), the dependent variable likelihood of use, and answers to exploratory questions were recorded and tested within directed correlations. Following a non-probability-sampling strategy, the study was completed by 331 physicians from Germany in the German language, of whom 301 (90.9%) fulfilled the study criteria (eg, being in regular contact with patients with dementia). These data were analyzed using a range of statistical methods to validate the dimensions of the DHCQ., Results: The DHCQ revealed good test theoretical measures-it showed excellent fit indexes (Tucker-Lewis index=0.98; comparative fit index=0.982; standardized root mean square residual=0.073; root mean square error of approximation=0.037), good internal consistency (Cronbach α=.83), and signs of moderate to large correlations between the DHCQ dimensions and the dependent variable. The correlations between the variables acceptance, attitude toward technology, technology experience, and payment for the time of use and the dependent variable likelihood of use ranged from 0.29 to 0.79, and the correlation between effort of the collection and likelihood of use was -0.80. In addition, we found high levels of skepticism regarding data protection, and the age of the participants was found to be negatively related to their technical experience and attitude toward technology., Conclusions: In the context of the results, increased communication between the medical and technology sectors and significantly more awareness raising are recommended to make the use of digital health apps more attractive to physicians as they can be adjusted to their everyday needs. Further research could explore the connection between areas such as adherence on the patient side and its impact on the likelihood of use by physicians., (©Markus Schinle, Christina Erler, Mayumi Kaliciak, Christopher Milde, Simon Stock, Marius Gerdes, Wilhelm Stork. Originally published in JMIR Formative Research (https://formative.jmir.org), 22.06.2022.)

Recently, digital apps have entered the market to enable the early diagnosis of dementia by offering digital dementia screenings. Some of these apps use Machine Learning (ML) to predict cognitive impairment. The aim of this work is to find explanations for the predictions of such a mobile application called DemPredict using methods from the field of Explainable Artificial Intelligence (XAI). In order to evaluate which method is best suited, different XAI approaches are used and compared. However, the comparability of the results is a key challenge. By evaluating the trustworthiness, stability, and computation time of the methods, it is possible to identify the optimal XAI approaches for the respective algorithms.

For a multiview autostereoscopic three-dimensional display based on the lenticular lens, the manufacturing errors and inhomogeneities of the lenticular sheet can deteriorate the view image quality. A calibration method is proposed by filtering the pixel mapping of all view images. Each view is first sequentially turned on to show a white test image, and the intensity distribution of every view will be analyzed. Then individual filter functions are derived and applied to the corresponding view images to correct the subpixel value. Experimental results show that the proposed method can solve view image loss and significantly improve the quality of stereoscopic images.

The data situation of laser-induced damage measurements after multiple-pulse irradiation in the ns-time regime is limited. Since the laser safety standard is based on damage experiments, it is crucial to determine damage thresholds. For a better understanding of the underlying damage mechanism after repetitive irradiation, we generate damage thresholds for pulse sequences up to N = 20 000 with 1.8 ns-pulses using a square-core fiber and a pulsed Nd:YAG laser. Porcine retinal pigment epithelial layers were used as tissue samples, irradiated with six pulse sequences and evaluated for damage by fluorescence microscopy. The damage thresholds decreased from 31.16 µJ for N = 1 to 11.56 µJ for N = 20 000. The reduction indicates photo-chemical damage mechanisms after reaching a critical energy dose., Competing Interests: The authors declare that there are no conflicts of interest related to this article., (© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.)

Internet- and mobile-based approaches have become increasingly significant to psychological research in the field of bipolar disorders. While research suggests that emotional aspects of bipolar disorders are substantially related to the social and global functioning or the suicidality of patients, these aspects have so far not sufficiently been considered within the context of mobile-based disease management approaches. As a multiprofessional research team, we have developed a new and emotion-sensitive assistance system, which we have adapted to the needs of patients with bipolar disorder. Next to the analysis of self-assessments, third-party assessments, and sensor data, the new assistance system analyzes audio and video data of these patients regarding their emotional content or the presence of emotional cues. In this viewpoint, we describe the theoretical and technological basis of our emotion-sensitive approach and do not present empirical data or a proof of concept. To our knowledge, the new assistance system incorporates the first mobile-based approach to analyze emotional expressions of patients with bipolar disorder. As a next step, the validity and feasibility of our emotion-sensitive approach must be evaluated. In the future, it might benefit diagnostic, prognostic, or even therapeutic purposes and complement existing systems with the help of new and intuitive interaction models., (©Henning Daus, Timon Bloecher, Ronny Egeler, Richard De Klerk, Wilhelm Stork, Matthias Backenstrass. Originally published in JMIR Mental Health (http://mental.jmir.org), 03.07.2020.)

Many experimental studies focus on the physical damage mechanisms of short-term exposure to laser radiation. In the nanosecond (ns) pulse range, damage in the Retinal Pigment Epithelium (RPE) will most likely occur at threshold levels due to bubble formation at the surface of the absorbing melanosome. The energy uptake of the melanosomes is one key aspect in modeling the bubble formation and damage thresholds. This work presents a thermal finite volume model for the investigation of rising temperatures and the temperature distribution of irradiated melanosomes. The model takes the different geometries and thermal properties of melanosomes into account, such as the heat capacity and thermal conductivity of the heterogeneous absorbing melanosomes and the surrounding tissue. This is the first time the size and shape variations on the melanosomes' thermal behavior are considered. The calculations illustrate the effect of the geometry on the maximum surface temperature of the irradiated melanosome and the impact on the bubble formation threshold. A comparison between the calculated bubble formation thresholds and the RPE cell damage thresholds within a pulse range of 3 to 5000 ns leads to a mean deviation of μ=22mJ/cm2 with a standard deviation of σ=21mJ/cm2. The best results are achieved between the simulation and RPE cell damage thresholds for pulse durations close to the thermal confinement time of individual melanosomes., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The focus of this paper was on finding wrist sensor-derived features for detecting highly acute fall risk from the sit-to-stand transitions performed in a non-ambulatory environment. Furthermore, the influence of the dominant and non-dominant hand on these features was investigated. A cohort of 174 older subjects was monitored for seven consecutive days in their home setting by using inertial sensors attached at the wrist. Based on the reported falls during a one-month follow-up phase, two groups were defined. Twenty-one time and frequency domain features were implemented for the quantitative assessment of extracted sit-to-stand transitions. The statistical analysis yielded two features that could convincingly distinguish fallers from non-fallers for the dominant hand, and six for the non-dominant hand. A novel feature, energy of the applied support during standing up, showed statistically good performance independently of on which hand the sensor node was worn, as well as for the dominant and non-dominant hand ([Formula: see text], [Formula: see text], and [Formula: see text], respectively). This paper overcomes limitations of clinical tests and shows a reliable application of wrist-worn bands in terms of assessment of highly acute fall risk. In addition, it reveals the sit-to-stand transition as a potential assessment source for the wrist-worn devices in the elderly population. Early assessment of the risk of falling in a widely accepted and non-stigmatized manner has the ability to bring crucial changes in fall prevention strategies, reducing the number of falls and the fall rate.

The probe length is investigated under the influence of the coherence length of Gaussian and Lorentzian spectra for the case that the focal point and the point of highest interference are matched in a strongly focused laser Doppler velocimetry setup (LDV). Isosurfaces of a -3  dB drop of the intensity maximum are estimated and suggested as an alternative, comprehensible way to define probe volumes. In the end, the equations are applied for an exemplary lidar setup to show the reduction of requirements for the coherence length of the laser source in comparison to unmatched cases.

Ethylene is a gaseous plant hormone controlling fruit ripening, flower opening, leaf senescence as well as abscission, and disease symptom development. Ethylene plays a critical role in the bacterial pathogen Xanthomonas euvesicatoria ( X. euvesicatoria )-elicited symptom development in tomato. This protocol describes the measurement of ethylene gas produced by tomato leaves infected with X. euvesicatoria . Infected leaflets are placed in a glass tube for 30 min without sealing. The glass tubes are then capped with a septa stopper, and incubated for an hour. A 1 ml gas sample is removed from the tube using a syringe and then injected into a gas chromatograph to quantify ethylene gas levels. This protocol will be applicable for other plants with other pathogens with modifications.

Manufacturer information, user experiences and product availability of assistive living technologies are usually not known to citizens or consultation centers. The different knowledge levels concerning the availability of technology shows the need for building up a knowledge base. The aim of this contribution is the definition of requirements in the development of knowledge bases for AAL consultations. The major requirements, such as a maintainable and easy to use structure were implemented into a web based knowledge base, which went productive in ~3700 consulting interviews of municipal technology information centers. Within this field phase the implementation of the requirements for a knowledge base in the field of AAL consulting was evaluated and further developed.

With the increasing number of laser applications in medicine and technology, accidental as well as intentional exposure of the human eye to laser sources has become a major concern. Therefore, a prediction model for ocular damage (PMOD) is presented within this work and validated for long-term exposure. This model is a combination of a raytracing model with a thermodynamical model of the human and an application which determines the thermal damage by the implementation of the Arrhenius integral. The model is based on our earlier work and is here validated against temperature measurements taken with porcine eye samples. For this validation, three different powers were used: 50mW, 100mW and 200mW with a spot size of 1.9mm. Also, the measurements were taken with two different sensing systems, an infrared camera and a fibre optic probe placed within the tissue. The temperatures were measured up to 60s and then compared against simulations. The measured temperatures were found to be in good agreement with the values predicted by the PMOD-model. To our best knowledge, this is the first model which is validated for both short-term and long-term irradiations in terms of temperature and thus demonstrates that temperatures can be accurately predicted within the thermal damage regime., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Many phytopathogenic type III secretion effector proteins (T3Es) have been shown to target and suppress plant immune signaling but perturbation of the plant immune system by T3Es can also elicit a plant response. XopX is a "core" Xanthomonas T3E that contributes to growth and symptom development during Xanthomonas euvesicatoria infection of tomato but its functional role is undefined. We tested the effect of XopX on several aspects of plant immune signaling. XopX promoted ethylene production and plant cell death (PCD) during X. euvesicatoria infection of susceptible tomato and in transient expression assays in Nicotiana benthamiana, which is consistent with its requirement for the development of X. euvesicatoria-induced disease symptoms. Additionally, although XopX suppressed flagellin-induced reactive oxygen species, it promoted the accumulation of pattern-triggered immunity (PTI) gene transcripts. Surprisingly, XopX coexpression with other PCD elicitors resulted in delayed PCD, suggesting antagonism between XopX-dependent PCD and other PCD pathways. However, we found no evidence that XopX contributed to the suppression of effector-triggered immunity during X. euvesicatoria-tomato interactions, suggesting that XopX's primary virulence role is to modulate PTI. These results highlight the dual role of a core Xanthomonas T3E in simultaneously suppressing and activating plant defense responses.

The work presented here describes the development and use of a three-dimensional thermo-dynamic model of the human eye for the prediction of temperatures and damage thresholds under irradiation. This model takes into account the blood flow by the implementation of a vectorial blood stream in the choroid and also uses the actual physiological extensions and tissue parameters of the eye. Furthermore it considers evaporation, radiation and convection at the cornea as well as the eye lid. The predicted temperatures were successfully validated against existing eye models in terms of corneal and global thermal behaviour. The model׳s predictions were additionally checked for consistency with in-vivo temperature measurements of the cornea, the irradiated retina and its damage thresholds. These thresholds were calculated from the retinal temperatures using the Arrhenius integral. Hence the model can be used to predict the temperature increase and irradiation hazard within the human eye as long as the absorption values and the Arrhenius coefficients are known and the damage mechanism is in the thermal regime., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In this article the problem of achieving fast scanning of a time-of-flight range sensor with a large optical receiver aperture at low system cost is targeted. The presented approach to solve this problem consists of a micromirror-based transmitter unit and a receiver unit consisting of a large aperture lens system with a small field of view and a detector array. A concept, which is called synchronous detector switching, is applied to the detector array. Thereby electronic steering of the small receiver field of view is possible. The overall approach is compared to alternative approaches, and the underlying concept of synchronous detector switching is demonstrated experimentally in an implementation of a three-dimensional time-of-flight range sensor. It is theoretically shown that the presented concept is potentially cheaper than the alternative approaches for applications with a field of view of less than 60×60°. After a discussion of the strengths and limitations of the approach, its effect on broader scientific issues is outlined.

XopD, a type III secretion effector from Xanthomonas euvesicatoria (Xcv), the causal agent of bacterial spot of tomato, is required for pathogen growth and delay of host symptom development. XopD carries a C-terminal SUMO protease domain, a host range determining nonspecific DNA-binding domain and two EAR motifs typically found in repressors of stress-induced transcription. The precise target(s) and mechanism(s) of XopD are obscure. We report that XopD directly targets the tomato ethylene responsive transcription factor SlERF4 to suppress ethylene production, which is required for anti-Xcv immunity and symptom development. SlERF4 expression was required for Xcv ΔxopD-induced ethylene production and ethylene-stimulated immunity. XopD colocalized with SlERF4 in subnuclear foci and catalyzed SUMO1 hydrolysis from lysine 53 of SlERF4, causing SlERF4 destabilization. Mutation of lysine 53 prevented SlERF4 sumoylation, decreased SlERF4 levels, and reduced SlERF4 transcription. These data suggest that XopD desumoylates SlERF4 to repress ethylene-induced transcription required for anti-Xcv immunity., (Copyright © 2013 Elsevier Inc. All rights reserved.)

In the growing field of pico-projectors, laser-based scanning systems may be advantageous over DLP- or LCoS-based imagers due to their potential for miniaturization, enhanced optical efficiency and cost reduction. The high energy density of a combined laser beam can, however, be hazardous to the human eye. Laser projection systems must therefore be identified with the laser class, depending on their maximum optical output power. This power limits the brightness of the displayed image, which is of particular interest for mobile applications. Various approaches to classifying laser devices by their wavelength and output power are described within the standards for laser safety. It is found that actual safety regulations cannot be directly applied to scanning systems. A detailed analysis of the optical conditions in terms of a two-dimensional extended light source is appropriate for the consideration of laser scanner devices. In this article, alternative ways of applying laser standards for scanning systems are discussed. The dependencies of maximum luminous flux from scanning system parameters are reviewed. It is shown that the evaluation of retinal light exposure in terms of existing laser regulations leads to an overestimation of the hazardous potential. Advanced investigations are proposed to support the definition of suitable criteria for the classification of laser scanning projectors.

Purpose: the method described here allows for automatic calculation of the fundus pulse from interferometric measurements., Method: a low intensity laser beam is coupled into the eye. Two strong reflections, one of the cornea and one of the retina, interfere on a high-speed complementary metal-oxide-semiconductor camera chip. After eye movement compensation, a speckle-free phase of the interferograms is calculated from a series of interference fringes. Then, the fundus pulsation is calculated from the phase shift between two consecutive interferograms., Problems: occurring speckle perturbs the fringe images, and therefore, classical geometrical movement compensation algorithms do not work with sufficient accuracy. The movement compensation algorithm needs to work without prior knowledge of the phase., Results: the proposed algorithms yield the fundus pulse from speckled interferograms, overcoming the above mentioned problems.

Purpose: To determine in vitro image qualities of artificial eyes achieved with spherical, aberration-free, average spherical aberration-correcting, and customized spherical aberration-correcting IOLs in centered, decentered, and tilted positions., Methods: The in vitro performance of these IOL models was determined by optical bench measurements. The experimental setup included a laser light source controlled by aperture stops that corresponded to 3- and 5-mm pupil apertures, an artificial eye with three alternative corneal models exhibiting low, intermediate, and high spherical aberration (SA), IOLs mounted to an immersed IOL holder that could be moved laterally and tilted, and a charge-coupled device camera and software to determine three-dimensional point spread function (PSF), modulation transfer function, and Strehl ratio., Results: Differences among the various lens models turned out to be low for a 3-mm pupil. For a pupil aperture of 5 mm, customized IOLs showed the best results for perfect lens positioning. With ongoing decentration and tilt, customized IOLs rapidly lost their advantages, particularly in corneas with high SA and IOLs of high diopters. Spherical IOLs were always inferior to aberration-free IOLs., Conclusions: Reasonably well-centered aberration-correcting IOLs may provide considerably better image quality than conventional spherical IOLs. In the presence of significant postoperative decentration and tilt of the IOL, aberration-free IOLs are the safest option among the various intraocular lens designs.

Background: Rapid herbivore-induced jasmonic acid (JA) accumulation is known to mediate many induced defense responses in vascular plants, but little is known about how JA bursts are metabolized and modified in response to repeated elicitations, are propagated throughout elicited leaves, or how they directly influence herbivores., Methodology/principal Findings: We found the JA burst in a native population of Nicotiana attenuata to be highly robust despite environmental variation and we examined the JA bursts produced by repeated elicitations with Manduca sexta oral secretions (OS) at whole- and within-leaf spatial scales. Surprisingly, a 2(nd) OS-elicitation suppressed an expected JA burst at both spatial scales, but subsequent elicitations caused more rapid JA accumulation in elicited tissue. The baseline of induced JA/JA-Ile increased with number of elicitations in discrete intervals. Large veins constrained the spatial spread of JA bursts, leading to heterogeneity within elicited leaves. 1(st)-instar M. sexta larvae were repelled by elicitations and changed feeding sites. JA conjugated with isoleucine (JA-Ile) translates elicitations into defense production (e.g., TPIs), but conjugation efficiency varied among sectors and depended on NaWRKY3/6 transcription factors. Elicited TPI activity correlated strongly with the heterogeneity of JA/JA-Ile accumulations after a single elicitation, but not repeated elicitations., Conclusions/significance: Ecologically informed scaling of leaf elicitation reveals the contribution of repeated herbivory events to the formation of plant memory of herbivory and the causes and importance of heterogeneity in induced defense responses. Leaf vasculature, in addition to transmitting long-distance damage cues, creates heterogeneity in JA bursts within attacked leaves that may be difficult for an attacking herbivore to predict. Such unpredictability is a central tenet of the Moving Target Model of defense, which posits that variability in itself is defensive.

There are various applications of physical activity monitoring for medical purposes, such as therapeutic rehabilitation, fitness enhancement or the use of physical activity as context information for evaluation of other vital data. Physical activity can be estimated using acceleration sensor-systems fixed on a person's body. By means of pattern recognition methods, it is possible to identify with certain accuracy which movement is being performed. This work presents a comparison of different methods for recognition of daily-life activities, which will serve as basis for the development of an online activity monitoring system.

Reliable signals are the basic prerequisite for most mobile ECG monitoring applications. Especially when signals are analyzed automatically, capable motion artifact detection algorithms are of great importance. This article presents different artifact detection algorithms for ECG systems with dry electrodes. The algorithms are based on the measurement of additional parameters that are correlated with the artifacts. We describe a mobile measurement system and the procedure used for the evaluation of these algorithms. The algorithms are assessed based upon their effect on QRS detection. The best algorithm improved sensitivity (Se) from 98.7% to 99.8% and positive predictive value (+P) from 98.3% to 99.9%, while 15% of the signal was marked as artifact. This corresponds to a decrease in false positive and false negative detected beats by 89.9%. Different metrics to evaluate the performance of an artifact detection algorithm are presented.

Background: Foldable intraocular lenses (IOLs) are established in ophthalmic surgery and increasingly more complex geometries are available. This study investigates different designs of the optics of the IOL as well as the imaging quality of these optics utilizing electron microscopic photographs and mathematical approximations., Method: Included in this study were two different lens powers of common IOLs (+ 13 D and + 26 D). All studied IOLs were processed depending upon their water content: Aqueous IOLs with up to 25 % water content were fixed with 2.5 % glutaraldehyde in 0.1 M phosphate buffer (mPP), and then contrasted with 2 % OsO (4) and processed in an alcohol series of 30 - 100 % propanol. Subsequently, the IOLs were transferred into EPON (epoxy resin) and polymerization took place at 60 degrees C. After hardening, the samples were cut out with a leaves saw and divided into halves. Afterwards these were polished with glass and diamond knifes at the ultramicrotom (Ultracut, Rückert-Jung). After coal vaporization measurement took place in the scanning electron microscope (DSM 962, Zeiss). In the case of dry stored IOLs, the samples were sputtered with Au-Pd 20 nm and afterwards measurement was performed as described above. The measurement of the optical imaging quality was performed with correctly and inversely oriented IOLs according to the standard EN ISO 11979 -- 2 by means of a measuring system which works on the basis of the point spread function (PSF) and/or the modulation transfer function (MTF). From this the Strehl ratio was computed in each case., Results: Utilizing a correlation of the electron microscopic investigation of the optics of different IOLs with their imaging quality (Strehl ratio), we were able to show that the optical design of the IOL has substantial influence on the imaging quality of an intraocular lens. In particular, with non-symmetrical designs of the optics (e. g., AR40 e; AMO) the orientation of an IOL in the eye is crucial; i. e., the Strehl ratio increased thereby from 0.68 to 0.87., Conclusions: The design of asymmetrical optics is crucial and much attention should be paid to the fact that the imaging quality can substantially be affected. A correct orientation of the lens within the eye is very important with these asymmetrical optics.

Purpose: To compare the imaging quality of several commercially available intraocular lenses (IOLs) using the modulation transfer function (MTF) method according to the requirements of the International Standard European Industrial Norm/International Organization for Standardization 11979., Setting: Universitat für Technik der Informationsverarbeitung, Universität Karlsruhe, Karlsruhe and Universitäts Augenklinik, Ulm, Ulm, Germany., Methods: Two refractive powers (+13 diopter [D] and +26 D) of each IOL type were tested. The imaging quality of all tested IOLs was measured before the injection test and in 5-minute intervals after the injection for 40 minutes. The measurement data were analyzed according to 2 quality criteria, Strehl ratio and the ISO condition. For analysis of the type of optical design, SEM images of the central cross section were taken of each IOL. Basic terms in optics such as MTF, resolution, and optical aberration are introduced, and their relevance for ophthalmology is discussed in detail. This paper represents an extensive study comparing the imaging quality of various IOLs including the comparison of measurements before and after injection through a cartridge as used for state-of-the-art implantation techniques. All measurements were performed using an MTF measurement system using a 546 nm optimized laser source and an effective aperture of 3.0 mm on the IOL according to ISO standard. An ISO standard eye model using an artificial cornea (spherical design) and a watery solution to simulate in vivo conditions was used., Results: All IOLs apart from 1 +26 D lens complied with ISO standard requirements. However, the imaging quality varied up to 49% depending on the optical design and the manufacturing quality., Conclusion: When the methods and materials recommended by the manufacturer for IOL injection through a cartridge were used, no long-term effect on the imaging quality of the IOLs was observed. However, the basic imaging quality of different designs and different manufacturers varied significantly (up to 50% at +26 D) IOLs and should be considered when choosing an IOL.

Background: Diabetes mellitus is one of the most common diseases in industrialized countries as well as in emerging economies such as India or China. One of the key technologies for diabetes therapy is semi-continuous monitoring of the glucose level of diabetics., Methods: Compared with skin-perforating techniques, optical measurement techniques promising good results bear the potential for high patient compliance with more frequent measurements. Due to its excellent optical properties, the anterior chamber and the aqueous humor (AH) contained therein offer promise for non-invasive in vivo glucose measurements. However, a number of strongly limiting factors, such as the precise optical properties of the eye, laser safety regulations and subconscious eye movements during the measurement period have to be considered for in vivo applications., Results: This article presents a high-resolution polarimetric measurement system that utilizes the optical rotatory dispersion (optical activity) of the glucose molecule for measurements of the glucose concentration in AH., Conclusion: Based on this example of a suitable optical measurement system, the special limitations and conditions that have to be considered for in vivo glucose measurement at the human eye are presented and analyzed. This includes the optical properties of the cornea and the anterior chamber, the impact of typical eye movements during a measurement and laser safety regulations.

Due to the increasing lifespan in the industrialized world the number of senior Diabetes patients is growing rapidly. Using non-invasive techniques, measurements of the blood sugar level could be done more frequently and hence diagnosis as well as therapy of type II Diabetes Mellitus can be improved especially for this group of senior patients. Especially polarimetric techniques measuring at the human eye offer promising properties for non-invasive and painless measurement. This article discusses different approaches for utilizing the polarizing properties of the Aqueous Humour (AH) for quantitative glucose measurements.

A possibility to significantly reduce the costs of public health systems is to increasingly use information technology. The Laboratory for Information Processing Technology (ITIV) at the University of Karlsruhe is developing a personal health monitoring system, which should improve health care and at the same time reduce costs by combining micro-technological smart sensors with personalized, mobile computing systems. In this paper we present how ubiquitous computing theory can be applied in the health-care domain.

The therapy of the cataract with the implantation of intraocular lenses is a great success story over the last 20 years. However cataract patients cannot accommodate anymore and need additional glasses for the far and near view. In the last 10 years bifocal concepts for intraocular lenses have been investigated with little success. Our new bifocal diffractive bifocal lens showed in clinical trials with 150 Patients an excellent visual performance. Less than 10% of the patients still use additional glasses. Due to the diffractive principle the lens can be manufactured very thin. Therefore the lens can be easily implanted through very small incisions. The lens shows the potential for the replacement of multifocal glasses.

All over the world about 10 million people suffer from blindness caused by an opaque, irreversible damaged and inoperable cornea. Many of these people still have intact retinal functions. After Prof. Heimann of the University of Köln miniaturized and implantable displays might help such people to restore partially their vision. Optical and physiological constraints of such vision aids are discussed.

A formula that can analyze the laser Doppler velocimeter spectrum was derived. The formula showed good agreement with computational experimental results. The use of a Fourier transform lens as detection optics was proposed and was found to be independent of the displacement of the object along the direction parallel to the optical axis. An experimental method was also proposed that can make the simultaneous measurement of velocity and displacement possible simply by adding a second detector. By using two detectors, not only can displacement of the surface be measured, but also the results of the speed measurement can be compensated for.

Contrast imaging of new multifocal intraocular lens (MIOL) designs with 5 and 7 refractive zones was examined by in vitro measurement of the modulation transfer function (MTF) and by testing contrast sensitivity with Regan 96% and 11% contrast sensitivity charts after "optical implantation" of MIOLs in 20 healthy subjects by means of a new optical device developed by Reiner. The results were compared with those obtained with a monofocal IOL and a diffractive MIOL. We found that the MTF of both refractive MIOLs showed a reduction in contrast at corresponding spatial frequencies compared with the monofocal and with the diffractive IOL, resulting in a Strehl ratio of below 30%. Contrast sensitivity after "optical implantation" was significantly reduced for the refractive 5- and 7-zone models in high contrast (Regan 96%), but for all MIOL models in low contrast (Regan 11%) compared with the monofocal IOL. The refractive 5-zone MIOL and diffractive MIOL showed no statistical difference in contrast sensitivity.

Space-variant optical elements are necessary for realizing optical interconnects of arbitrary design. For such applications, planar holographic optical elements offer the highest degree of flexibility and ease of production; however their diffraction-based operation gives rise to chromatic aberrations. Here estimates for the number of independent space-variant interconnects, their spatial tolerances, and their wavelength stability are considered for close-cascade, and related, geometries.

A miniaturized sensor head for the optical measurement of velocities of fluids based on laser Doppler velocimetry is demonstrated. Holographic optical elements mounted on a glass substrate are used for beam splitting and deflection. Volume holograms in dichromated gelatin exhibit good optical efficiency (75% transmission of a cascade of two holographic optical elements). With diffractive devices one can achieve achromatic behavior that makes the sensor insensitive to wavelength drifts or mode hopping of a semiconductor laser.

A concept for parallel optoelectronic bus-type interconnections (many participants-many participants) is given. The choices between multimode and single-mode fan-ins in free-space optical systems are discussed. When one single space-invariant multiple beam-splitting system is used for fan-out and fan-in simultaneously, the energy requirements for communications scale with 2N (for N participants on each busline), which is compared with N(2) for space-variant systems. A simple demonstration experiment with a Dammann grating used as a multiple beam splitter is shown, and in a design example the theoretical performance is discussed.

Zero-order gratings are grating structures with a period that is small compared with the wavelength of light. Only the directly transmitted or reflected light, the zero diffraction order, is nonevanescent and propagates in a distance from the grating. Thus the grating behaves like a slab of ordinary homogeneous material with an effective refractive index. By varying the material composition, i.e., by variation of the duty cycle of the grating, the effective refractive index can be changed. A grating with variable duty cycle therefore behaves like a material with distributed index. Based on such artificial materials, distributed-index elements are proposed. The physical principle is demonstrated with water waves.

During the past three years 27 patients with medullary and/or brainstem cavities were examined with MRI at the Institute of Roentgenology, and we report the radiological MRI correlative findings. Five patients were operated: postoperative MRI examinations were compared with preoperative studies. Syringomyelia was present in 21 cases, syringobulbia in 2, and syringobulbomyelia in 4. Additional pathology such as the Arnold Chiari malformation or hydrocephalus was found at the craniospinal junction in 8 patients. Two instances of associated intraspinal tumours were noted too. In all cases the syringomyelic cavities involved the cervical cord and in most of them the lesion extended down to the thoracic or even lumbar level. Several patients were shown to have multilocular cavities. In the patients with syringomyelia a syringoarachnoidal shunting procedure was performed. This resulted in cyst collapse as proved by postoperative MRI examinations; neurological symptomatology was ameliorated too. Conventional radiological imaging with computed tomography (CT) and myelography was not as efficient as MRI in imaging syringomyelia. The extent of intramedullary cavities as well as the presence of associated pathology is best appreciated on sagittal MRI. The use of special surface coils clearly results in better image quality due to higher resolution. According to our experience MRI should be the primary examination in syringomyelia; myelography and CT are obsolete in the management of syringomyelia; the insertion of a syringoarachnoidal shunt is a convenient surgical procedure, resulting in clinical amelioration in most cases.

Fifty-four patients with angiographically confirmed peripheral vascular disease (PVD) were examined in order to find out whether the occlusive form of this disease can be better diagnosed by measuring the reappearance time and mean velocity of the blood flow during reactive hyperemia than by determining the peripheral systolic blood pressure, using Doppler ultrasound for both measurements. It was shown that the Doppler pressure was only reliable for a screening diagnosis of PVD. However, using the reappearance time of reactive hyperemia, it was possible to distinguish specific localization types of sclerosis; while reactive hyperemia already reached its half maximum in controls in 4.6 s this occurred in the stenosis type of PVD after 6.9 s, in the upper leg occlusion type after 21.6 s, in the lower leg occlusion type after 46.6 s, and in the multilevel disease after 70.1 s. The delay in the half-maximum reappearance time was significantly different, not only in comparison with controls (P less than 0.001) but also in the specific types of occlusive PVD as compared with one another (P less than 0.01). Regarding the intensity of velocity it could also be shown that the mean velocity of blood flow during reactive hyperemia was lower in all patients with PVD than in controls. Again this alteration during reactive hyperemia was significant, not only in comparison with controls (P less than 0.001), but also when the specific stages of severity according to Fontaine were compared with one another (P less than 0.05).2+n the basis of these findings it can be stated that in

Thalamic-striatal damage of symmetric bilateral distribution was found in four severely asphyxiated neonates born at term. Two patients showed evidence of bilateral thalamic-striatal necrosis and two showed hemorrhage of the same distribution. The four patients had a common history of prolonged asphyxia in the neonatal period combined with severe acidosis and respiratory insufficiency. The outcome was lethal in all children. Three patients survived for some time and showed additional evidence of generalized brain damage including cortical necrosis and subcortical leucomalacia and one patient was found to have intravital calcification of the putamen at 14 days of age. The appearance of thalamic-striatal damage in US, CCT and NMR imaging is discussed. Thalamic-striatal damage may not be detectable by US until several days after the initial insult. US does not permit a distinction between necrosis and hemorrhage, but CCT and NMR imaging may be successful. Only five infants with a comparable pattern of brain damage due to asphyxia have been described so far. Our own studies seem to indicate that thalamic-striatal damage is the hallmark of more widespread brain damage, and that it will be found more frequently if carefully looked for in asphyxiated neonates born at term.

Brewster telescopes are useful for anamorphic image formation or for anamorphic beam compression. With an array of micro-Brewster telescopes a wide uniform beam can be compressed into many beams of a smaller diameter. Thus arrays of microprisms might form an array of micro-Brewster telescopes, which can be used as array illuminator.

We report construction and successful operation of a ripple carry full adder with an architecture based on symbolic substitution logic. The principal piece of hardware is a microchannel spatial light modulator. Examples of its operation are given for addition of 4-bit numbers.

The perfect shuffle permutation is an important interconnection scheme in digital optical computing. Various methods suggested for the optical implementation of the perfect shuffle need an anamorphic imaging system. Instead of cylinder lenses Brewster prism telescopes can be used to achieve the desired ratio of 2:1 for horizontal and vertical magnifications. To reduce the rather large distortion of prism telescopes the Brewster concept can be combined with the Amici concept of a straight view dispersion prism.

Two cases of colloid cyst of the third ventricle are reported. Their computed tomographic (CT), magnetic resonance (MR) and neuropathological features are presented. The MR findings were different in the two cases for reasons not yet fully explained, full biochemical and biophysical analyses of the cyst contents not being available. Neuropathologically, the only significant difference was the abundant presence of cholesterin crystals in the colloid of case 1 and their absence in case 2. One of our cases is also peculiar from a CT point of view, since it was primarily hypodense and did not enhance on intravenous contrast administration.