Search

We introduce a novel co-design method for autonomous moving agents' shape attributes and locomotion by combining deep reinforcement learning and evolution with user control. Our main inspiration comes from evolution, which has led to wide variability and adaptation in Nature and has significantly improved design and behavior simultaneously. Our method takes an input agent with optional user-defined constraints, such as leg parts that should not evolve or are only within the allowed ranges of changes. It uses physics-based simulation to determine its locomotion and finds a behavior policy for the input design that is used as a baseline for comparison. The agent is randomly modified within the allowed ranges, creating a new generation of several hundred agents. The generation is trained by transferring the previous policy, which significantly speeds up the training. The best-performing agents are selected, and a new generation is formed using their crossover and mutations. The next generations are then trained until satisfactory results are reached. We show a wide variety of evolved agents, and our results show that even with only 10% of allowed changes, the overall performance of the evolved agents improves by 50%. If more significant changes to the initial design are allowed, our experiments' performance will improve even more to 150%. Our method significantly improved motion tasks without changing body structures, and it does not require considerable computation resources as it works on a single GPU and provides results by training thousands of agents within 30 minutes.

Improving access to kidney transplants remains a priority for the transplant community. However, many medical, psychosocial, geographic, and socioeconomic barriers exist that prevent or delay transplantation for candidates with certain conditions. There is a lack of consensus regarding how to best approach many of these issues and barriers, leading to heterogeneity in transplant centers' management and acceptance practices for a variety of pretransplant candidate issues. In this review, we address several of the more common contemporary patient medical and psychosocial barriers frequently encountered by transplant programs. The barriers discussed here include kidney transplant candidates with obesity, older age, prior malignancy, cardiovascular disease, history of nonadherence, and cannabis use. Improving understanding of how to best address these specific issues can empower referring providers, transplant programs, and patients to address these issues as necessary to progress toward eventual successful transplantation., (Copyright © 2024 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

In this article, we propose DeepTree, a novel method for modeling trees based on learning developmental rules for branching structures instead of manually defining them. We call our deep neural model "situated latent" because its behavior is determined by the intrinsic state -encoded as a latent space of a deep neural model- and by the extrinsic (environmental) data that is "situated" as the location in the 3D space and on the tree structure. We use a neural network pipeline to train a situated latent space that allows us to locally predict branch growth only based on a single node in the branch graph of a tree model. We use this representation to progressively develop new branch nodes, thereby mimicking the growth process of trees. Starting from a root node, a tree is generated by iteratively querying the neural network on the newly added nodes resulting in the branching structure of the whole tree. Our method enables generating a wide variety of tree shapes without the need to define intricate parameters that control their growth and behavior. Furthermore, we show that the situated latents can also be used to encode the environmental response of tree models, e.g., when trees grow next to obstacles. We validate the effectiveness of our method by measuring the similarity of our tree models and by procedurally generated ones based on a number of established metrics for tree form.

Introduction: This study aimed to develop, implement, and test a visuo-haptic simulator designed to explore the buoyancy phenomenon for freshman engineering students enrolled in physics courses. The primary goal was to enhance students' understanding of physical concepts through an immersive learning tool. Methods: The visuo-haptic simulator was created using the VIS-HAPT methodology, which provides high-quality visualization and reduces development time. A total of 182 undergraduate students were randomly assigned to either an experimental group that used the simulator or a control group that received an equivalent learning experience in terms of duration and content. Data were collected through pre- and post-tests and an exit-perception questionnaire. Results: Data analysis revealed that the experimental group achieved higher learning gains than the control group ( p = 0.079). Additionally, students in the experimental group expressed strong enthusiasm for the simulator, noting its positive impact on their understanding of physical concepts. The VIS-HAPT methodology also reduced the average development time compared to similar visuo-haptic simulators. Discussion: The results demonstrate the efficacy of the buoyancy visuo-haptic simulator in improving students' learning experiences and validate the utility of the VIS-HAPT method for creating immersive educational tools in physics., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Neri, Noguez, Escobar-Castillejos, Robledo-Rella, García-Castelán, Gonzalez-Nucamendi, Magana and Benes.)

Selection for yield at high planting density has reshaped the leaf canopy of maize, improving photosynthetic productivity in high density settings. Further optimization of canopy architecture may be possible. However, measuring leaf angles, the widely studied component trait of leaf canopy architecture, by hand is a labor and time intensive process. Here, we use multiple, calibrated, 2D images to reconstruct the 3D geometry of individual sorghum plants using a voxel carving based algorithm. Automatic skeletonization and segmentation of these 3D geometries enable quantification of the angle of each leaf for each plant. The resulting measurements are both heritable and correlated with manually collected leaf angles. This automated and scaleable reconstruction approach was employed to measure leaf-by-leaf angles for a population of 366 sorghum plants at multiple time points, resulting in 971 successful reconstructions and 3,376 leaf angle measurements from individual leaves. A genome wide association study conducted using aggregated leaf angle data identified a known large effect leaf angle gene, several previously identified leaf angle QTL from a sorghum NAM population, and novel signals. Genome wide association studies conducted separately for three individual sorghum leaves identified a number of the same signals, a previously unreported signal shared across multiple leaves, and signals near the sorghum orthologs of two maize genes known to influence leaf angle. Automated measurement of individual leaves and mapping variants associated with leaf angle reduce the barriers to engineering ideal canopy architectures in sorghum and other grain crops., Competing Interests: James C. Schnable has an equity interests in Data2Bio, a company that provides genotyping services using the same protocol employed for genotyping in this study., (©2021 Tross et al.)

Procedural modeling has produced amazing results, yet fundamental issues such as controllability and limited user guidance persist. We introduce a novel procedural model called PICO (Procedural Iterative Constrained Optimizer) and PICO-Graph that is the underlying procedural model designed with optimization in mind. The key novelty of PICO is that it enables the exploration of generative designs by combining both user and environmental constraints into a single framework by using optimization without the need to write procedural rules. The PICO-Graph procedural model consists of a set of geometry generating operations and a set of axioms connected in a directed cyclic graph. The forward generation is initiated by a set of axioms that use the connections to send coordinate systems and geometric objects through the PICO-Graph, which in turn generates more objects. This allows for fast generation of complex and varied geometries. Moreover, we combine PICO-Graph with efficient optimization that allows for quick exploration of the generated models and the generation of variants. The user defines the rules, the axioms, and the set of constraints; for example, whether an existing object should be supported by the generated model, whether symmetries exist, whether the object should spin, etc. PICO then generates a class of geometric models and optimizes them so that they fulfill the constraints. The generation and the optimization in our implementation provides interactive user control during model execution providing continuous feedback. For example, the user can sketch the constraints and guide the geometry to meet these specified goals. We show PICO on a variety of examples such as the generation of procedural chairs with multiple supports, generation of support structures for 3D printing, generation of spinning objects, or generation of procedural terrains matching a given input. Our framework could be used as a component in a larger design workflow; its strongest application is in the early rapid ideation and prototyping phases.

We introduce QuadStack, a novel algorithm for volumetric data compression and direct rendering. Our algorithm exploits the data redundancy often found in layered datasets which are common in science and engineering fields such as geology, biology, mechanical engineering, medicine, etc. QuadStack first compresses the volumetric data into vertical stacks which are then compressed into a quadtree that identifies and represents the layered structures at the internal nodes. The associated data (color, material, density, etc.) and shape of these layer structures are decoupled and encoded independently, leading to high compression rates (4× to 54× of the original voxel model memory footprint in our experiments). We also introduce an algorithm for value retrieving from the QuadStack representation and we show that the access has logarithmic complexity. Because of the fast access, QuadStack is suitable for efficient data representation and direct rendering. We show that our GPU implementation performs comparably in speed with the state-of-the-art algorithms (18-79 MRays/s in our implementation), while maintaining a significantly smaller memory footprint.

The positivity principle states that people learn better from instructors who display positive emotions rather than negative emotions. In two experiments, students viewed a short video lecture on a statistics topic in which an instructor stood next to a series of slides as she lectured and then they took either an immediate test (Experiment 1) or a delayed test (Experiment 2). In a between-subjects design, students saw an instructor who used her voice, body movement, gesture, facial expression, and eye gaze to display one of four emotions while lecturing: happy (positive/active), content (positive/passive), frustrated (negative/active), or bored (negative/passive). First, learners were able to recognize the emotional tone of the instructor in an instructional video lecture, particularly by more strongly rating a positive instructor as displaying positive emotions and a negative instructor as displaying negative emotions (in Experiments 1 and 2). Second, concerning building a social connection during learning, learners rated a positive instructor as more likely to facilitate learning, more credible, and more engaging than a negative instructor (in Experiments 1 and 2). Third, concerning cognitive engagement during learning, learners reported paying more attention during learning for a positive instructor than a negative instructor (in Experiments 1 and 2). Finally, concerning learning outcome, learners who had a positive instructor scored higher than learners who had a negative instructor on a delayed posttest (Experiment 2) but not an immediate posttest (Experiment 1). Overall, there is evidence for the positivity principle and the cognitive-affective model of e-learning from which it is derived., Competing Interests: Conflict of interestThe authors report no conflicts of interest., (© The Author(s) 2021.)

Changes in canopy architecture traits have been shown to contribute to yield increases. Optimizing both light interception and light interception efficiency of agricultural crop canopies will be essential to meeting the growing food needs. Canopy architecture is inherently three-dimensional (3D), but many approaches to measuring canopy architecture component traits treat the canopy as a two-dimensional (2D) structure to make large scale measurement, selective breeding, and gene identification logistically feasible. We develop a high throughput voxel carving strategy to reconstruct 3D representations of sorghum from a small number of RGB photos. Our approach builds on the voxel carving algorithm to allow for fully automatic reconstruction of hundreds of plants. It was employed to generate 3D reconstructions of individual plants within a sorghum association population at the late vegetative stage of development. Light interception parameters estimated from these reconstructions enabled the identification of known and previously unreported loci controlling light interception efficiency in sorghum. The approach is generalizable and scalable, and it enables 3D reconstructions from existing plant high throughput phenotyping datasets. We also propose a set of best practices to increase 3D reconstructions' accuracy., Competing Interests: The authors are not aware of any conflict of interest arising from drafting this manuscript., (© 2020 The Authors. Plant Direct published by American Society of Plant Biologists and the Society for Experimental Biology and John Wiley & Sons Ltd.)

Computational models of plants have identified gaps in our understanding of biological systems, and have revealed ways to optimize cellular processes or organ-level architecture to increase productivity. Thus, computational models are learning tools that help direct experimentation and measurements. Models are simplifications of complex systems, and often simulate specific processes at single scales (e.g. temporal, spatial, organizational, etc.). Consequently, single-scale models are unable to capture the critical cross-scale interactions that result in emergent properties of the system. In this perspective article, we contend that to accurately predict how a plant will respond in an untested environment, it is necessary to integrate mathematical models across biological scales. Computationally mimicking the flow of biological information from the genome to the phenome is an important step in discovering new experimental strategies to improve crops. A key challenge is to connect models across biological, temporal and computational (e.g. CPU versus GPU) scales, and then to visualize and interpret integrated model outputs. We address this challenge by describing the efforts of the international Crops in silico consortium., (© 2020 Society for Experimental Biology and John Wiley & Sons Ltd.)

Most mountain ranges are formed by the compression and folding of colliding tectonic plates. Subduction of one plate causes large-scale asymmetry while their layered composition (or stratigraphy) explains the multi-scale folded strata observed on real terrains. We introduce a novel interactive modeling technique to generate visually plausible, large scale terrains that capture these phenomena. Our method draws on both geological knowledge for consistency and on sculpting systems for user interaction. The user is provided hands-on control on the shape and motion of tectonic plates, represented using a new geologically-inspired model for the Earth crust. The model captures their volume preserving and complex folding behaviors under collision, causing mountains to grow. It generates a volumetric uplift map representing the growth rate of subsurface layers. Erosion and uplift movement are jointly simulated to generate the terrain. The stratigraphy allows us to render folded strata on eroded cliffs. We validated the usability of our sculpting interface through a user study, and compare the visual consistency of the earth crust model with geological simulation results and real terrains.

Surface remeshing is a key component in many geometry processing applications. The typical goal consists in finding a mesh that is (1) geometrically faithful to the original geometry, (2) as coarse as possible to obtain a low-complexity representation and (3) free of bad elements that would hamper the desired application (e.g., the minimum interior angle is above an application-dependent threshold). Our algorithm is designed to address all three optimization goals simultaneously by targeting prescribed bounds on approximation error , minimal interior angle and maximum mesh complexity (number of vertices). The approximation error bound is a hard constraint, while the other two criteria are modeled as optimization goals to guarantee feasibility. Our optimization framework applies carefully prioritized local operators in order to greedily search for the coarsest mesh with minimal interior angle above and approximation error bounded by . Fast runtime is enabled by a local approximation error estimation, while implicit feature preservation is obtained by specifically designed vertex relocation operators. Experiments show that for reasonable angle bounds ( ) our approach delivers high-quality meshes with implicitly preserved features (no tagging required) and better balances between geometric fidelity, mesh complexity and element quality than the state-of-the-art.

Multi-scale models can facilitate whole plant simulations by linking gene networks, protein synthesis, metabolic pathways, physiology, and growth. Whole plant models can be further integrated with ecosystem, weather, and climate models to predict how various interactions respond to environmental perturbations. These models have the potential to fill in missing mechanistic details and generate new hypotheses to prioritize directed engineering efforts. Outcomes will potentially accelerate improvement of crop yield, sustainability, and increase future food security. It is time for a paradigm shift in plant modeling, from largely isolated efforts to a connected community that takes advantage of advances in high performance computing and mechanistic understanding of plant processes. Tools for guiding future crop breeding and engineering, understanding the implications of discoveries at the molecular level for whole plant behavior, and improved prediction of plant and ecosystem responses to the environment are urgently needed. The purpose of this perspective is to introduce Crops in silico (cropsinsilico.org), an integrative and multi-scale modeling platform, as one solution that combines isolated modeling efforts toward the generation of virtual crops, which is open and accessible to the entire plant biology community. The major challenges involved both in the development and deployment of a shared, multi-scale modeling platform, which are summarized in this prospectus, were recently identified during the first Crops in silico Symposium and Workshop.

The fovea is one of the most studied retinal specializations in vertebrates, which consists of an invagination of the retinal tissue with high packing of cone photoreceptors, leading to high visual resolution. Between species, foveae differ morphologically in the depth and width of the foveal pit and the steepness of the foveal walls, which could influence visual perception. However, there is no standardized methodology to measure the contour of the foveal pit across species. We present here FOVEA, a program for the quantification of foveal parameters (width, depth, slope of foveal pit) using images from histological cross-sections or optical coherence tomography (OCT). FOVEA is based on a new algorithm to detect the inner retina contour based on the color variation of the image. We evaluated FOVEA by comparing the fovea morphology of two Passerine birds based on histological cross-sections and its performance with data from previously published OCT images. FOVEA detected differences between species and its output was not significantly different from previous estimates using OCT software. FOVEA can be used for comparative studies to better understand the evolution of the fovea morphology in vertebrates as well as for diagnostic purposes in veterinary pathology. FOVEA is freely available for academic use and can be downloaded at: http://estebanfj.bio.purdue.edu/fovea.

Medical procedures often involve the use of the tactile sense to manipulate organs or tissues by using special tools. Doctors require extensive preparation in order to perform them successfully; for example, research shows that a minimum of 750 operations are needed to acquire sufficient experience to perform medical procedures correctly. Haptic devices have become an important training alternative and they have been considered to improve medical training because they let users interact with virtual environments by adding the sense of touch to the simulation. Previous articles in the field state that haptic devices enhance the learning of surgeons compared to current training environments used in medical schools (corpses, animals, or synthetic skin and organs). Consequently, virtual environments use haptic devices to improve realism. The goal of this paper is to provide a state of the art review of recent medical simulators that use haptic devices. In particular we focus on stitching, palpation, dental procedures, endoscopy, laparoscopy, and orthopaedics. These simulators are reviewed and compared from the viewpoint of used technology, the number of degrees of freedom, degrees of force feedback, perceived realism, immersion, and feedback provided to the user. In the conclusion, several observations per area and suggestions for future work are provided.

The flexible pinhole camera (FPC) allows flexible modulation of the sampling rate over the field of view. The FPC is defined by a viewpoint and a map specifying the sampling locations on the image plane. The map is constructed from known regions of interest with interactive and automatic approaches. The FPC provides inexpensive 3D projection that allows rendering complex datasets quickly, in feed-forward fashion, by projection followed by rasterization. The FPC supports many types of data, including image, height field, geometry, and volume data. The resulting image is a coherent nonuniform sampling (CoNUS) of the dataset that matches the local variation of the dataset's importance. CoNUS images have been successfully implemented for remote visualization, focus-plus-context visualization, and acceleration of expensive rendering effects such as surface geometric detail and specular reflection. A video explaining and demonstrating the FPC is at http://youtu.be/kvFe5XjOPNM.

In order to advance the scientific understanding of carbon exchange with the land surface, build an effective carbon monitoring system, and contribute to quantitatively based U.S. climate change policy interests, fine spatial and temporal quantification of fossil fuel CO(2) emissions, the primary greenhouse gas, is essential. Called the "Hestia Project", this research effort is the first to use bottom-up methods to quantify all fossil fuel CO(2) emissions down to the scale of individual buildings, road segments, and industrial/electricity production facilities on an hourly basis for an entire urban landscape. Here, we describe the methods used to quantify the on-site fossil fuel CO(2) emissions across the city of Indianapolis, IN. This effort combines a series of data sets and simulation tools such as a building energy simulation model, traffic data, power production reporting, and local air pollution reporting. The system is general enough to be applied to any large U.S. city and holds tremendous potential as a key component of a carbon-monitoring system in addition to enabling efficient greenhouse gas mitigation and planning. We compare the natural gas component of our fossil fuel CO(2) emissions estimate to consumption data provided by the local gas utility. At the zip code level, we achieve a bias-adjusted Pearson r correlation value of 0.92 (p < 0.001).

We propose a novel approach for the reconstruction of urban structures from 3D point clouds with an assumption of Manhattan World (MW) building geometry; i.e., the predominance of three mutually orthogonal directions in the scene. Our approach works in two steps. First, the input points are classified according to the MW assumption into four local shape types: walls, edges, corners, and edge corners. The classified points are organized into a connected set of clusters from which a volume description is extracted. The MW assumption allows us to robustly identify the fundamental shape types, describe the volumes within the bounding box, and reconstruct visible and occluded parts of the sampled structure. We show results of our reconstruction that has been applied to several synthetic and real-world 3D point data sets of various densities and from multiple viewpoints. Our method automatically reconstructs 3D building models from up to 10 million points in 10 to 60 seconds.

Processing and interpreting the face is generally very important because one is often required to make rapid decisions in life on the basis of meagre information. Ninety-two volunteers used a computer-assisted test battery to assess 40 profiles of patients (8 skeletal Class II and 8 skeletal Class III patients, each pre- and postoperatively, with 8 skeletal Class I photographs serving as controls). On a 7-point Likert scale the raters were asked to evaluate aesthetics and a few relevant personality traits (e.g. unintelligent, inhibited, aggressive, brutal). The photographs of the two patient groups were rated significantly less attractive and intelligent prior to surgery than the photographs of the control group. In respect of personality traits, the photographs of the skeletal Class III group differed more strongly from normal ones. In respect of aesthetics and intelligence, both patient groups benefited markedly from surgery. For some personality traits, significant interactions were found between the two groups on pre-post comparison. The method underlying the study is useful for evaluating the outcome of orthognathic surgery, but also indicates the strongly generalized and unconscious processes involved in the estimation of people's personality traits, especially when these concern deviations from the socially normal condition., (Copyright © 2011 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

(In, Ga)N nanostructures show great promise as the basis for next generation LED lighting technology, for they offer the possibility of directly converting electrical energy into light of any visible wavelength without the use of down-converting phosphors. In this paper, three-dimensional computation of the spatial distribution of the mechanical and electrical equilibrium in nanoheterostructures of arbitrary topologies is used to elucidate the complex interactions between geometry, epitaxial strain, remnant polarization, and piezoelectric and dielectric contributions to the self-induced internal electric fields. For a specific geometry-nanorods with pyramidal caps-we demonstrate that by tuning the quantum well to cladding layer thickness ratio, h(w)/h(c), a minimal built-in electric field can be experimentally realized and canceled, in the limit of h(w)/h(c) = 1.28, for large h(c) values.

Urban simulation models and their visualization are used to help regional planning agencies evaluate alternative transportation investments, land use regulations, and environmental protection policies. Typical urban simulations provide spatially distributed data about number of inhabitants, land prices, traffic, and other variables. In this article, we build on a synergy of urban simulation, urban visualization, and computer graphics to automatically infer an urban layout for any time step of the simulation sequence. In addition to standard visualization tools, our method gathers data of the original street network, parcels, and aerial imagery and uses the available simulation results to infer changes to the original urban layout and produce a new and plausible layout for the simulation results. In contrast with previous work, our approach automatically updates the layout based on changes in the simulation data and thus can scale to a large simulation over many years. The method in this article offers a substantial step forward in building integrated visualization and behavioral simulation systems for use in community visioning, planning, and policy analysis. We demonstrate our method on several real cases using a 200 GB database for a 16,300 km2 area surrounding Seattle.

In 2006, levels of seven indicator polychlorinated biphenyl congeners (PCB28, 52, 101, 118, 138, 153, and 180) in blood serum of 202 blood donors residing for more than 2 years in five urban areas included in the Czech Human Biomonitoring project were measured by GC/MS/MS method. PCB congeners 138, 153 and 180 accounted for about 97% of the sum of the indicator congeners analyzed. Overall, the median and 95th percentile of the most abundant congener PCB 153 were 438 ng/g lipid and 1079 ng/g lipid, respectively. The highest median levels were found in Uherské Hradiste (669 ng/g lipid) and Ostrava (672 ng/g lipid in males compared to 341 ng/g lipid in females). Serum PCB concentrations were significantly associated with age, gender, place of residence and smoking habit, but not with body mass index and education. The results suggest the importance of PCB body burden in the Czech general population and the existence of hot spots.

The developed method for mercury speciation analysis has been validated and used for the biomonitoring study of mercury species in human hair. Statistical evaluation proved the reliability of simplified determination of inorganic mercury (difference between total mercury and methylmercury). The results of the validation showed that the method is very well suitable for the determination of both species of mercury in hair for biomonitoring purposes. Non-exposed schoolchildren from three areas in the western and central part of the Czech Republic were chosen as the target group. Tenth of a microgram per gram of the total mercury were generally found in the analyzed hair; values higher than 1 microg g(-1) were detected only exceptionally. Comparable results were obtained for two western areas and differed significantly from those for the third area located in the central part of the Czech Republic. In the areas examined, the mean methylmercury contents amounted to 23-46% of the total mercury in the hair. The results confirm an assumption that exposure to mercury does not pose a significant risk to the population in the Czech Republic.

The human biomonitoring (HBM) is an integral part of Environmental Health Monitoring System in the Czech Republic since 1994. Selected biomarkers of the internal dose (heavy metals, PCBs) and cytogenetic analysis of peripheral lymphocytes as a biomarker of the exposure/effect to/of environmental genotoxic factors are systematically followed up in the blood and urine of adults (blood donors), in children aged 8 to 10 years, and in the breast milk of nursing mothers. Selected outputs documented the declining trend of blood lead levels, with the recent reference value of 80 mg/l for men, and the rising trend of blood selenium levels in adults, but not in children. PCBs and chlorinated pesticides in human milk show a long-term downward trend, but still higher than in neighbouring countries. The frequency of aberrant cells revealed a downward trend, but the increase obtained in the last monitored period needs to be explained. Further HBM activities are required to demonstrate the corresponding trends and to reduce human exposure and health risks.

The Human Biological Monitoring (HBM) project was launched in the Czech Republic in 1994 as a part of the nation-wide Environmental Health Monitoring System to assess the exposure of the Czech general population to a broad spectrum of environmental contaminants. Over the years 2001-2003, the concentrations of lead (Pb), cadmium (Cd), and mercury (Hg) were determined in whole blood of 1188 adults (blood donors) and 333 children and in urine of 657 adults and 619 children. In adults, the median blood lead (B-Pb) level was 33microg/l. Men had higher B-Pb levels than women (medians 37microg/l vs. 25microg/l). Significantly higher B-Pb levels were observed in smokers compared to non-smokers (36microg/l vs. 31microg/l). In children, no sex-dependent differences were observed (median 31microg/l). In total, the median blood Cd level (B-Cd) in adults was 0.5microg/l. Smokers showed a median B-Cd level about 3 times as high as non-smokers (1.3microg/l vs. 0.40microg/l). Neither sex- nor age-related differences were observed in B-Cd levels. In 65% of children, B-Cd levels were below the limit of detection (LOD). The overall median urinary cadmium level (U-Cd) in adults was 0.31microg/g creatinine. Significantly higher U-Cd levels were found in women (median 0.39microg/g creatinine) compared to men (0.29microg/g creatinine). No significant differences were found between smokers and non-smokers. In more than 50% of children, the U-Cd level was below the LOD (=0.2microg/l). The median blood mercury (B-Hg) level in adults was 0.89microg/l. Significant differences were found between smokers (0.80microg/l) and non-smokers (0.92microg/l), and between men and women (0.86microg/l vs. 0.94microg/l). The median B-Hg level in children was 0.42microg/l and no sex-related differences were observed. The median urinary mercury (U-Hg) levels were 0.63microg/g creatinine in adults and 0.37microg/g creatinine in children. Significantly higher U-Hg levels were obtained in women and non-smokers compared to men and smokers, respectively. The B-Pb, B-Hg, U-Cd, and U-Hg levels significantly correlated with age. The following reference values were recommended for the period 2001-2003: 80, 65 and 55microg/l for B-Pb and 3.1, 4.0 and 1.5microg/l for B-Hg in men, women and children, respectively; 1.1microg/l and 1.2microg/g creatinine for B-Cd and U-Cd, respectively, in adult non-smokers; 5.4 and 12.0microg/g creatinine for U-Hg in men and women, respectively, and 3.7 and 5.5microg/g creatinine for U-Hg in boys and girls, respectively. The previous reference values for B-Pb and B-Cd needed revision and were reduced.

Variations in the levels of Cu, Se and Zn in blood were analyzed in relation to gender, age, BMI, smoking and hormonal contraception. The blood samples were collected from 3,207 blood donors (2,362 men, 845 women) during years 1996-2003. Blood concentrations of these elements were in the same range as those found for populations of other European countries. Significant differences exist between men and women, in blood concentration, for Cu (840 microg Cu.l(-1) vs. 970 microg Cu.l(-1), p<0.01) and Zn (6,780 microg Zn.l(-1) vs. 6,235 microg Zn.l(-1), p<0.01) only. The level of Cu in relation to age is increasing in men, but decreasing in women. The level of Se in relation to age increases regardless of sex. Concentrations of Zn rise with age in women group, only. Positive correlation was found between BMI and level of Cu only for group of men. For Se levels and BMI differences exist only in men namely between groups <20 and >35 (82 microg Se.l(-1) vs. 92 microg Se.l(-1)). Slight positive correlations exist between Zn concentration and BMI in women only. The significant differences were found between smokers and non-smokers for Cu in men (850 microg Cu.l(-1) vs. 830 microg Cu.l(-1)) and Se (81 microg Se.l(-1) vs. 84 microg Se.l(-1)). The smoking has not significant influence on concentration of Zn in the blood. The hormonal contraception significantly increases the concentration of Cu in blood (920 microg Cu.l(-1) vs. 1,270 microg Cu.l(-1), p<0.01). The levels of Se and Zn in blood are not influenced using hormonal contraception.

Over a 5-year period, from 1996 to 2001, blood selenium levels were recorded in a set of 2414 healthy blood donors (1781 men and 633 women; 880 smokers and 1534 nonsmokers) living in four selected areas of the Czech Republic. About 100 blood samples per year and region were analyzed using the HGA method. The internal and external quality controls of this method were performed throughout the duration of the study. In general, blood selenium concentrations (81.9 and 106.7 microg/l for median and 90th percentile, respectively) did not reach optimum values; in approximately 10% of the population sample, values lower than 60 microg/l were detected. Nonetheless, the values obtained increased significantly, with median concentrations of 73.2 microg/l in 1996 and 91.5 microg/l in 2001. The percentage of subjects with a whole blood selenium level of less than 60 microg/l also decreased from nearly 20% in 1996 to 0.2% in 2001. No substantial regional or gender-related differences were observed, but significantly lower blood selenium levels were found in smokers as opposed to nonsmokers. Although mild selenium deficiency continues to be observed, the data presented do not indicate extremely low selenium levels in the population sample.

Knowledge of normal levels of concentrations of trace elements (Cd, Cr, Cu, Hg, Pb, Se and Zn) in the population serve, among others, in the designing of regulations of exposure limits and prevention of diseases caused by deficiency in essential trace elements. Concentrations of the named elements in the hair of children in the Czech population were determined by means of atomic absorption spectrometry. The samples of hair were collected during 1994- 2001 from 3,556 children (1,741 boys and 1,815 girls, average age 9.9 years). Mineralization in a microwave digestion system was used following a washing procedure. The accuracy of results was checked by means of the control materials CRM Human Hair GBW 07601. Values of concentrations of the trace elements in hair found for children were (in medians) 0.14 microg Cd.g(-1), 0.22 microg Cr.g(-1), 12 microg Cu.g(-1), 0.19 microg Hg.g(-1), 1.6 microg Pb.g(-1), 0.22 microg Se.g(-1) and 124 microg Zn.g(-1), respectively. Statistically significant differences between boys and girls were found for Cd, Cu and Zn. Concentrations of the elements under study correspond to the published values for the non-exposed population.

The method of Guo et aL (AnaL Chim. Acta, 1997, 349, 313-318) for the determination of the toxicologically relevant arsenic in urine was verified and then used for the determination of arsenic in urine of the Czech population for monitoring purposes. Statistical evaluation at the level alpha = 0.05 did not prove any significant differences between industrial and agricultural regions, between males and females and smokers and nonsmokers. Likewise no differences were found among children in all the regions monitored. In the adult population small differences were found between some regions but these differences were not dependent on industrial pollution. The values of toxicologically relevant arsenic are low for all regions. The summarised value of the median for all groups together is 3.5 microg (g creatinine)(-1).

Knowledge of normal levels of concentrations of trace elements (Cd, Pb, Hg, Cu, Zn, and Se) in the population serves, among others, in design of regulations concerning health protection, determination of exposition limits and prevention of diseases caused by deficiency of trace elements. Concentrations of the named elements in urine of the Czech population were determined by means of atomic absorption spectrometry. The urine has been collected during 1996-2000 from 1192 individuals (816 males and 376 females, average age 34.6 years) and 2008 children (1052 boys and 956 girls, average age 9.9 years). Mineralization in a microwave digestion system was used in sample preparation. The accuracy of results was checked by means of the Control Materials Seronorm 403,125 and BioRad 69,041. Values of concentrations of the trace elements in urine found for adult (medians) were 0.36 microgram Cd.g-1 creatinine, 10.6 micrograms Cu.g-1 creatinine, 0.68 microgram Hg.g-1 creatinine, 3.3 micrograms Pb.g-1 creatinine, 6.2 micrograms Se.g-1 creatinine, and 397 micrograms Zn.g-1 creatinine, respectively. Statistically significant differences between men and women have been found in the concentrations of Cu and Hg. In the juvenile population following concentrations have been found: 0.29 microgram Cd.g-1 creatinine, 16.1 micrograms Cu.g-1 creatinine, 0.32 microgram Hg.g-1 creatinine, 4.8 micrograms Pb.g-1 creatinine, 10.2 micrograms Se.g-1 creatinine and 460 micrograms Zn.g-1 creatinine. Statistically significant differences between boys and girls were found only in Cu and Hg concentrations. Concentrations of the studied elements correspond to the published values concerning population not exposed professionally.

The retrospective study evolution of trends in concentrations of Cd, Pb, Cu and Se in the population of the Czech Republic over 30 years period could be useful in design of regulations concerning health protection, prevention of diseases caused by deficiency of trace elements and have considerable economic importance. Concentrations of the named elements in the serum were determined by means of atomic absorption spectrometry (AAS) after mineralisation in a microwave digestion system. The 1433 samples of serum (730 males and 703 females, average age 48.7 and 49.1 years respectively) from a time period 1970-1995 were obtained from the Serum bank of National Institute of Public Health and volunteers (1999). Serum samples from the years 1970, 1975, 1980, 1985, 1990, 1995 and 1999 were examined. The accuracy of the results was checked by means of the Control material Seronorm Whole Blood 404,107 and Seronorm Serum 704,121, Nycomed. The concentration of Cd had a decreasing trend for the years 1975-1999 (0.82 microgram Cd.l-1 vs 0.47 microgram Cd.l-1). The levels of Pb are falling in the interval 1970-1980 (15.6 micrograms Pb.l-1 vs. 6.6 micrograms Pb.l-1). In year 1985 concentration of Pb increased (10.7 micrograms Pb.l-1) but subsequently decreased again (1995--6.4 micrograms Pb.l-1). In year 1999, it was 8.9 micrograms.l-1. The concentration of Cu decreased in period 1970-1990 (1525 micrograms Cu.l-1 vs. 990 micrograms Cu.l-1). From 1990 to 1999 the levels of Cu had an increasing tendency (1999--1060 micrograms Cu.l-1). Levels of Se in the interval 1970-1985 were surprisingly equal (58.1 micrograms Se.l(-1)-54.4 micrograms Se.l-1). However in the interval 1986-1990 the level of Se sharp declined (38.3 micrograms Se.l-1). Since 1990 levels of Se in serum increased again, up to 67.1 micrograms Se.l-1 in 1999. Statistically significant differences between men and women were found only in Cu and Pb concentrations. Concentrations of under study elements corresponded to the published values concerning unexposed population.

This study aimed at determining blood concentrations of lead (B-Pb) and cadmium (B-Cd) in a group of 1215 healthy blood donors (895 males, 320 females) and 758 children (397 boys, 361 girls) aged 10 years, sampled in 1996-1998 in four districts of the Czech Republic. The analysis was performed using atomic absorption spectrometry. The median B-Pb values were lower in children (34 mg/L) than in adults. In the group of adults, the level was significantly higher in men (46 mg/L) than in women (29 mg/L). In none of the groups the 90th percentile exceeded the value of 100 mg/L. The B-Cd values in adults depended on smoking habit (median non-smokers: 0.5 mg/L, male smokers--1.2 mg/L, female smokers--1.0 mg/L). In children, more than 50% of values were under the limit of detection. The obtained values were used to propose reference values for the Czech population.

Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine the concentrations of 32 elements in the human liver and kidney and 20 elements in the bone, obtained from 70 autopsied dead individuals (54 males, 16 females) between 18 and 76 yr of age from the North Bohemia territory of the Czech Republic. Geometric means, median, minimal-maximal range, as well as distribution and correlation analysis were calculated. Some significant differences among tissue concentrations of trace elements of the women and men were found. In the liver, medians of the concentrations of some elements were higher for men than that for women (Al: 770 vs 610 microg/kg; As: 42 vs 27 microg/kg; Cd: 1800 vs 1390 microg/kg; Rb: 3955 vs 3210 microg/kg; V: 160 vs 105 microg/kg). On the contrary, the content of other elements for men was lower (Bi: 0.8 vs 3.2 microg/kg; Cr: 57 vs 72 microg/kg; Hg: 228 vs 325 microg/kg; Zn: 57.1 vs 68.5 mg/kg). In the kidney of men, there were higher contents of Al (360 vs 245 microg/kg) and Hg (135 vs 75 microg/kg) and lower contents of Zn (47.7 vs 59.7 mg/kg) and I (135 vs 220 microg/kg) than those of women. In the case of bone, the concentrations of Cu and Rb were higher for men (1410 microg Cu/kg and 405 microg Rb/kg, respectively) than for women (655 microg Cu/kg and 285 microg Rb/kg, respectively). On the contrary, the content of Mn was considerably lower for men (110 microg Mn/kg) than for women (215 microg Mn/kg).

Knowledge of normal levels of concentrations of trace elements (Cd, Pb, Hg, Cu, Zn, and Se) in the population serves, among others, in design of regulations concerning health protection, determination of exposure limits and prevention of diseases caused by deficiency of trace elements. Concentrations of the named elements in whole blood of the Czech population were determined by means of atomic absorption spectrometry. The blood was collected during 1996-1998 from 1,216 blood donors (896 males and 320 females, average age 33 years) and 758 children (397 boys and 361 girls, average age 9.9 years). Mineralisation in a microwave digestion system was used in sample preparation. The accuracy of results was checked by means of the Control material Seronorm Whole Blood 404107 and Seronorm Serum 704121, Nycomed. Values of concentrations of the trace elements in blood found for adult (medians) were 0.7 microgram Cd.l-1, 800 micrograms Cu.l-1, 0.78 microgram Hg.l-1, 41 micrograms Pb.l-1, 76 micrograms Se.l-1, and 5,800 micrograms Zn.l-1, respectively. Statistically significant differences between men and women have been found in the concentrations of Cu, Hg, Pb, and Zn. In the juvenile population following medians of concentrations have been found: 0.15 microgram Cd.l-1, 1,047 micrograms Cu.l-1, 0.46 microgram Hg.l-1, 34 micrograms Pb.l-1, 69 micrograms Se.l-1, and 8,180 micrograms Zn.l-1. Statistically significant differences between boys and girls were found only in Pb and Zn concentrations. Concentrations of the studied elements correspond to the published values concerning population not exposed professionally.

The sensation of adequate taste detection can be associated with satisfaction of food intake. The impairment of taste detection may be associated with the development of obesity. Taste detection is determined hereditarily, but it can be influenced also by the occurrence of neuropathy. To find an explanation for these phenomena, we investigated 73 patients with diabetes mellitus (DM) 2 (i.e., non-insulin-dependent DM); 11 patients with DM 1 (i.e., insulin-dependent DM); 12 obese patients (body-mass index >30) without DM; and 29 control patients. All subjects underwent electrogustometric examination with Hortmman's electrogustometer. During this examination, we obtained electrical thresholds of taste by stimulating appropriate parts of the tongue. We stimulated the apex, middle, and near tongue radix areas on both sides. The resulting value is the average on the left and right sides of the mentioned areas. We considered a value of less than 40 microA to be normal. Values in excess of 100 microA are considered as hypogeusia. Values between 40 and 100 microA are taken as borderline, and ageusia is in excess of 500 microA. According to these criteria, in the DM 2 group, we found 40% of patients with hypogeusia, whereas in the DM 1 group, we found 33% of patients; 25% of patients were in the obese group. Among normal subjects (people without obesity or DM), no hypogeusia was found. We found ageusia in 5% of patients with DM 2, in 3% of patients with DM 1, and in 14% of obese patients. Among normal subjects, we found no ageusia. These results support the hypothesis that diminished taste detection can evoke hyperphagia and later obesity.

The biological monitoring of toxic and essential metals in biological material is important for the study of influence of environmental conditions on the human body. In this work, the determination of Cd, Pb and Hg in blood, urine and hair of children has been performed by atomic absorption spectroscopy. The electrothermal atomisation with Zeeman background correction was used for Pb and Cd determination and mercury was determined using Trace Mercury Analyser TMA 254. Methylmercury in hair was determined simultaneously. To check the method, SRM Lyphochek Urine Metal control--Biorad, Seronorm Trace Elements--Nycomed and GWB Human Hair (China) were used. The group of more than 100 children were chosen for the study. Statistical tests were used for the evaluation of the obtained results. The concentrations of all elements in all types of samples correspond to the "normal contents" published for the non-exposed population.

In the framework of the system of monitoring the environmental impact on population health, the concentration of lead, cadmium and selenium in blood and cadmium in urine was measured in adults (n = 670), children (n = 599) and umbilical blood (n = 549) using atomic absorption spectrophotometry. Furthermore, cytogenetic analysis of peripheral lymphocytes in all population groups under study was investigated. The median blood Pb level for the overall group of adults (47.8 micrograms/l, i.e. 0.23 mumol/1) was significantly higher in men (51.5 micrograms/l, i.e. 0.25 mumol/l). Smoking significantly influenced the blood Pb level in women. The 90th percentile in no group exceeded the value of 100 micrograms/l (0.48 mumol/l). The median blood Cd level in adults (0.9 microgram/l, i.e. 0.008 mumol/l) depends on smoking habit (1.25 micrograms/l, i.e. 0.01 mumol/l). The median urine Cd level was 0.585 microgram/g creatinine (0.59 mumol/mole creatinine) in adults and 0.37 microgram/g creatinine (0.37 mumol/mole creatinine) in children. The median blood Se level (53.5 micrograms/l, i.e. 0.68 mumol/l) was found to be higher in the group of non-smokers (57.5 micrograms/l, i.e 0.73 mumol/l). Lead and selenium level were significantly lower in the umbilical blood. Cytogenetic analysis results showed age-dependent average percentages of aberrant cells: 1.1% in umbilical blood, 1.27% in children and 1.71 in adults in line with the reference values for the Czech population.

The biological monitoring of essential metals in blood, urine and hair became important for the control of biological processes and for the study of the influence of environmental conditions on the human organism. To determine the normal level of copper and zinc in the children population group of Central Bohemia (Benesov), 98 samples of whole blood, 133 samples of urine and 135 samples of hair have been analysed by means of atomic absorption spectroscopy. The mineralisation of blood and hair samples in the microwave oven and 3-fold dilution of urine were used for the sample preparation. Arithmetic and geometric means as well as median and ratio Zn/Cu were calculated. The concentration of the elements under study in all samples did not differ from the values published in the literature. Some differences between girls and boys have been found.

To the food of 33 diabetic patients typ I (in the age of about 15 years) organically bound chromium was added for 6 weeks. The influence on the metabolic compensation could not be proven, although in some individuals of this group the favorable effect of chromium can not be excluded.

The effect of 3 diets with different proportion of milk proteins on retention of arsenic was studied in mice. Arsenic was administered via drinking water in concentration 50 mg As [III] per litre labelled with 74As in amount 2.96 MBq per 100 ml. After 2, 4, 8, 16 and 32 days of exposure the mice in groups of 6 each from all 3 experimental cohorts were decapitated and the content of 74As was determined in whole body, blood, liver, kidneys, spleen, lungs and heart by measuring of the activity in Gamma Scintillation Counter Tesla. From the intake of drinking water and amount of arsenic found in the experimental animals was calculated retention of arsenic in mice at different exposure intervals in all three diets. The values of arsenic found at the exposure intervals in examined materials of all three experimental cohorts were compared. The results obtained indicate that a milk diet has no adverse effect at exposure to arsenic in the sense of enhancing of its retention in mice at given experimental conditions. The found data seemed to suggest that the milk protein rich diet caused retardation of the increase of arsenic concentrations in blood, liver and kidneys that might lead at a lower exposure rate to a decrease in arsenic content in tissues of exposed animals.

Biliary excretion of arsenic and its distribution in the organism were studied in golden hamsters after administration of Na3(74)AsO3 and Na2H74AsO4 solutions. Significant differences between the two valency forms of arsenic were found in the biliary excretion rate as well as in the cumulative biliary excretion of 74As. The arsenic biliary excretion after treatment with 74AS [III] [4.98 /+- 7.1, or 0.6 [0.2 - 1.1] percents of the administered dose] than that after 74As [V] application. On the other hand, arsenic excretion in the urine and stool were higher after the administration of pentavalent arsenic. The contents of 74As in the liver, kidneys, blood plasma and GIT wall were higher after the application of 74As [III]. It has been again confirmed tha compared to rats the hamster [similarly as the other laboratory animals] exhibits a significantly lower concentration of 74As in red blood cells [differences ranged by 2 orders of magnitude].

The paper deals with excretion of As(III) and As(V) in the urine of mice exposed to a toxic concentration of As(III) (250 mg/1) in drinking water. After the exposures of 2, 6, and 8 days, the mice were given i.m. a solution of 74As(III) labeled sodium arsenite in a dose of 1.3 mg As(III)/kg b.w. and an activity of 3 muCi/l ml. After the sacrifice of the animal, the urine was drawn off directly from the bladder. The urine samples were subjected to separation of As(III) from As(V) by using a paper radiochromatography technique. The results showed that unexposed control mice excreted one-half of the administered As(III) in the form of As(V). Mice exposed to arsenic in drinking water exceted already, after 2 days of exposure, four-fifths of the applied As(III) in the form of As(V), after 4 days of exposure the proportion of As(V) was more than 95%, and after 8 days of exposure only traces of As(III) were present. The authors discussed the possibility of the biotransformation of As(III) to As(V) on arsenic tolerance.

Penetration of beryllium through the placenta and its distribution in the organs after intravenous administration of BeCl2 in a dose of 0.1 mg/kg was studied in a series of experiments on ICR SPF mice. To trace the fate of beryllium, an isotope in the form of 7BeCl2 in an amount of 111kBq per animal was used. This dose was administered to a group of females before fertilization, on the 7th and 14th day of pregnancy, and to control animals. The animals were killed on the 18th to 19th day of pregnancy and the content of beryllium in the foetuses and its distribution in the organs of the mothers were determined by measuring activity. It has been found that beryllium penetrates through the placenta with difficulty, however, part of the dose administered circulated in the blood long enough for Be to penetrate the foetuses. Of interest is the finding that beryllium in the dose administered influenced the number of foetuses of the exposed females. This finding deserves detailed evaluation in the test of dominant lethal mutations.

The effect of trivalent arsenic on the C14-thymidine and C14-uridine incorporation into the liver nucleic acid molecules was studied in groups of mice exposed to 3.3 mmol . l-1 sodium arsenite in drinking water for 2, 4, 8, 16 and 32 days. In each exposure group, 18 h before the animals were killed by decapitation, six to ten mice were injected with 0.1 ml of C14-thymidine or C14-uridine of an activity of 0.37 MBq. The radioactivity of liver DNA and liver RNA fractions isolated and separated by extraction from the mouse liver homogenate was measured on a Betazcint BZ 5,000 scintillation counter and expressed as cpm . mg-1 of isolated nucleic acids. Initially, the rates at which the labeled thymidine and uridine nucleosides incorporated into the nucleic acid molecules showed a marked drop below the control value, then started to rise again, continuing to gradually increase as the time of arsenic exposure was increasing; they attained the control value on day 8, and at the last interval of observation (i.e. at 32 days of exposure to arsenic) they reached, respectively, 143% and 127% of the control value. The initial drop in the rate of nucleoside incorporation is believed to reflect the general metabolic inhibition caused by arsenic; the subsequent enhancement of the process of incorporation is ascribed to the induction of enzymes that are involved in the development of a tolerance for arsenic.