• They are usually dedicated to computational modeling of specific molecules: proteins, nucleic acids, lipid membranes, carbohydrates or water. (wikipedia.org)
  • We invite papers presenting computational investigations of large-scale molecules (highly functionalized polymers, biomolecules, aromatics, etc. (aiche.org)
  • Computational molecular modeling for the assessment of nanoparticle toxicity: interactions with biomolecules. (cdc.gov)
  • Computational cost was reduced by representing the solvent moiety of the systems implicitly by a generalized Born solvent model. (tum.de)
  • Endpoint methods save computational cost by omitting the simulation of intermediate states, i.e. only the endpoint states of a molecular process are considered. (tum.de)
  • The conference is arranged under the slogan "On the threshold of the XXI-th Century: the main results and look into the Future",- with attracting of the leading scientists of the World Science Schools for discussions of the modern problems of applied mathematics, computational methods and mathematical modelling in different natural areas. (netlib.org)
  • Date: Thu, 7 Jul 94 14:56:52 CDT Subject: Algorithms for Macromolecular Modeling Algorithms for Macromolecular Modeling an interdisciplinary workshop September 30--October 2, 1994 Kansas Institute for Theoretical and Computational Science University of Kansas at Lawrence This is a special workshop on algorithms and parallel implementations for macromolecular dynamics, protein folding, and structure refinement, including the treatment of quantum effects. (netlib.org)
  • Computational methods play a crucial role in developing quantitative models of biological systems at all levels of complexity. (gvsu.edu)
  • This course will cover three groups of topics in computational structural biology: protein structure prediction, molecular simulations and structure-based drug design, focusing on sequence-structure-function relationships in biomolecules. (gvsu.edu)
  • Computational modelling of functional molecules and materials. (lu.se)
  • We use structure based modeling and computational protein design methods to optimize the protein sequence of proteins and peptides in order to control their assembly. (lu.se)
  • Further, I will discuss recent theoretical and practical progress in using experimental NMR and SAXS data to refine computational models of biomolecules. (lu.se)
  • Barbara Webb studies perceptual systems for the control of behaviour, by building computational and physical (robot) models of the hypothesised mechanisms. (lu.se)
  • He has published multiple important papers in this area and he is senior author on the paper describing the anatomically constrained model of the bee central cortex which is the biological and computational foundation of the project. (lu.se)
  • Biomolecules such as proteins and nucleic acids are at the heart of virtually all fundamental cellular processes. (loria.fr)
  • Is it possible to understand the molecular structure and function of proteins and nucleic acids in enough detail to make accurate predictions about structure and function? (stanford.edu)
  • Encapsulation in self-assembled lipid structures has been shown to increase the stability of large biomolecules, including proteins and nucleic acids (NAs), which has many potential applications in the food and pharmaceutical industries. (lu.se)
  • In these models, molecules are represented not by individual atoms, but by "pseudo-atoms" approximating groups of atoms, such as whole amino acid residue. (wikipedia.org)
  • Thus, chiral biomolecules absorb chiral light in a way that lets us understand the structure of the molecules. (lsu.edu)
  • Evolutionary design has gained significant attention as a useful tool to accelerate the design process by automatically modifying molecular structures to obtain molecules with the target properties. (nature.com)
  • The use of deep neural network models to predict the properties of these molecules enabled more versatile and efficient molecular evaluations to be conducted by using the proposed method repeatedly. (nature.com)
  • This model suggested new possible interactions between molecules inside cells that cannot currently be studied in real cells. (elifesciences.org)
  • Finally, the model predicted that small molecules such as food, water and drugs would move more slowly through cells as they become stuck or trapped by larger molecules. (elifesciences.org)
  • The structural and functional characterization of molecules (isolated or combined in complexes), along with the quantification, modeling and prediction of biological phenomena, requires multidisciplinary research to be conducted involving biology, physics, chemistry, bioinformatics and mathematics. (aviesan.fr)
  • For all the systems studied, it is demonstrated that ions and water molecules modelled as rigid-bodies interacting via pair-wise empirical potentials are capable of exhibiting a wide range of water structure morphologies. (bham.ac.uk)
  • Therefore, IRAMIS implements with lasers, time-resolved spectroscopies in the range from femtosecond to the millisecond, to study the dynamics of molecular systems, like for example DNA biomolecules, or chromophore molecules for photovoltaics. (cea.fr)
  • make these clusters ideal as model systems to understand how the primary sequence of processes is affected by surrounding atoms or molecules. (lu.se)
  • Coarse-grained models have found practical applications in molecular dynamics simulations. (wikipedia.org)
  • Research methods include interactive, web-based visualization tools and atomic-detail molecular simulations. (h-its.org)
  • Using molecular dynamics simulations of a comprehensive atomistic model cytoplasm we found that protein-protein interactions may destabilize native protein structures, whereas metabolite interactions may induce more compact states due to electrostatic screening. (elifesciences.org)
  • Currently the simulations are limited, and can only model parts of simple cells for less than a thousandth of a second. (elifesciences.org)
  • Here we elucidate the molecular mechanism of these drugs by combining experiments and simulations. (rsc.org)
  • These can include weather forecasting and climate research, as well as molecular modelling and simulations of flight plans and spacecraft aerodynamics. (europa.eu)
  • Using molecular dynamics simulations in explicit water, I investigated different homopeptides. (fu-berlin.de)
  • From the simulations, parameters relevant for a full model description, which employs the inhomogeneous partially rotating chain, are derived. (fu-berlin.de)
  • Molecular simulations sample well defined thermodynamic ensembles, thus providing a representation of the physical world in silico. (elifesciences.org)
  • For example, a frequently noted shortcoming of molecular dynamics (MD) simulations is its dependence on the force field, that is, simplified representation of the electronic ground state potential energy. (elifesciences.org)
  • Considering the stochastic nature of common sampling algorithms such as molecular dynamics simulations, biomolecular trajectories represent a multidimensional random walk of which the analysis is especially prone to suffer from sampling deficiencies ( Hess, 2002 ). (elifesciences.org)
  • The various conformations adopted by the biomolecules by virtue of their flexibility are studied by a dual experience - theory approach, with quantum chemical simulations. (cea.fr)
  • Applications of quantum chemical calculations to investigations of molecular and materials properties, as well as development and applications of classical reaction dynamics simulations. (lu.se)
  • In the former projects atomistic and coarse-grained molecular dynamics and Monte Carlo simulations will be used together with experimental techniques such as scattering and circular dichroism, whereas the third project is focused on atomistic simulations solely. (lu.se)
  • A more detailed, atomic-level description of the structure, dynamics and compaction of IDPs, may however, be obtained from molecular simulations, but these need to be validated or generated by comparison with experiments. (lu.se)
  • We seek to use the hybrid system to monitor membrane processes, including mechanical properties of the membrane and interactions with biomolecules. (lu.se)
  • By utilizing mathematical models to describe molecular behavior, physical chemists strive to unravel the mysteries behind the fundamental processes that shape our world. (freescience.info)
  • In our group, we develop and investigate methods to calculate free-energy differences in a computationally efficient yet accurate manner and apply free-energy calculations to biophysical research questions concerning the behavior of biomolecules in solution. (tum.de)
  • Students of chemistry and related areas develop their understanding of molecular behavior and chemical reactivity through years of study that cannot be condensed into a few pages. (nationalacademies.org)
  • Those snapshots join into movies that can show molecular behavior over a microsecond. (doe.gov)
  • They started out by examining the structure and molecular behavior of millions of atoms in lignin - and how it behaves in water and changes with subtle alterations in its sequence and structure. (doe.gov)
  • Pauline Kergus uses artificial intelligence to model the thermal behavior of buildings. (lu.se)
  • In order to explore this feature, it is important to model building's thermal behavior in order to enable the use of demand-side management control strategies. (lu.se)
  • Therefore, characterizing the structure, dynamics and conformational changes of biomolecules can help understand the molecular mechanisms of underlying diseases, and hopefully prevent them by designing drugs. (loria.fr)
  • The functions of biomolecules are often linked to conformational changes on a molecular level. (fu-berlin.de)
  • By decreasing the degrees of freedom much longer simulation times can be studied at the expense of molecular detail. (wikipedia.org)
  • Atomistic resolution models alone are presently not efficient enough to handle large system sizes and simulation timescales. (wikipedia.org)
  • We are mounting a two-pronged attack on this problem using both molecular dynamics simulation and molecular modeling. (stanford.edu)
  • This session solicits theoretical, simulation, and experimental studies that address aspects of both natural and synthetic biomolecule folding and assembly. (confex.com)
  • A technique called molecular dynamics simulation solves Newton's equation of motion for each individual atom over incredibly small time intervals, Smith says. (doe.gov)
  • Coarse-grained models are presently often used as components of multiscale modeling protocols in combination with reconstruction tools (from coarse-grained to atomistic representation) and atomistic resolution models. (wikipedia.org)
  • Various types of mathematical models and systems analyses of biological networks have further been used to gain a better understanding of the sources and regulatory mechanisms of such variability. (mdpi.com)
  • The molecular mechanisms that control these fate decisions in SSCs are largely unknown transcriptional programs critical for SSC function. (utsa.edu)
  • Research is focused on studying the molecular mechanisms involved in the pathogenesis of Vibrio cholerae , the bacterium that causes cholera, and Francisella tularensis , the bacterium that causes tularemia. (utsa.edu)
  • We encourage submissions that focus on fundamental biophysical thermodynamic and transport properties, mechanisms, and models. (confex.com)
  • Nevertheless, much remains unknown about the exact molecular determinants and mechanisms of these glycan-mediated processes. (uci.edu)
  • Biomathematics to create dynamic or quantitative modeling of biological systems. (aviesan.fr)
  • Molecular Biotechnology is our strategy to investigate, design, and improve biomolecules and biological systems. (boku.ac.at)
  • Biological systems require precise folding, recognition, and self-assembly behaviors to form complex nanostructures and molecular machines. (confex.com)
  • He is a full professor at the Technical University of Munich, holding the chair 'Mathematical Modelling of Biological Systems', associate faculty at the Wellcome Trust Sanger Institute as well as adjunct faculty at the Northwestern University. (lu.se)
  • The researchers' approach, which introduces covalent guanine quantum defect chemistry as a potential design concept for biosensors, has broad application and allows molecular sensors to be created without impairing fluorescence in the NIR. (photonics.com)
  • For the hydrated sulfate and ferricyanide ions, rigid-body modelling of the clusters is capable of replicating the physical chemistry of these systems, with both exhibiting a size-dependent suppression of dangling OH bonds, provisionally consistent with infrared photodissociation spectroscopy of size selected hydrated ions. (bham.ac.uk)
  • Researchers at the Center for Molecular Biophysics at Oak Ridge National Laboratory (ORNL) and the University of Tennessee (UT) in Knoxville have long used supercomputers to model and study lignin polymers and their interactions with cellulose. (doe.gov)
  • The group developed an optical model of a chiral biomolecular film on a plasmonic metasurface. (lsu.edu)
  • The model showed that detectable enhancements in the chiroptical signals from the biomolecules were only possible when tight spectral overlap exists between the plasmonic and biomolecular chiral responses. (lsu.edu)
  • These biomolecular machines - cytoskeletal filaments driven by molecular motors - are each only a few billionths of a metre (nanometres) in size. (europa.eu)
  • Magnetic nanoparticles are used as a molecular tag, converting the biomolecular concentrations into the magnetic stray field, which can be detected by PHR magnetoresistive element as a change of its output voltage signal. (mdpi.com)
  • Our goal is to understand RNA function in terms of molecular structure and dynamics using a variety of biophysical and biological tools. (stanford.edu)
  • Biophysical approaches to obtain 'images' of molecular functioning and "see" the living organism more clearly. (aviesan.fr)
  • Molecular modeling is the field of characterizing structure of biomolecules. (loria.fr)
  • The SPINUS program is a feed-forward neural network (FFNN) system developed over the last 8 years for the prediction of 1 H NMR properties from the molecular structure. (acs.org)
  • However, since the atomic parameters relate nonlinearly to diffraction patterns, structure solution requires having an initial model within the radius of convergence of a minimization procedure that can relate the atomic model to the diffraction data. (iucr.org)
  • The model shows that some proteins have a much less rigid structure in cells than they do in isolation, whilst others are able to work together more closely to carry out certain tasks. (elifesciences.org)
  • As no experimental structure is available, we provide a model of the TMPRSS2 equilibrium structure and its fluctuations by relaxing an initial homology structure with extensive 330 microseconds of all-atom molecular dynamics (MD) and Markov modeling. (rsc.org)
  • Resveratrol exhibits a wide range of beneficial properties, and this may be due to its molecular structure, which endow resveratrol with the ability to bind to many biomolecules. (hindawi.com)
  • Its basic structure consists of two phenolic rings bonded together by a double styrene bond, which forms the 3,5,4′-Trihydroxystilbene (molecular weight 228.25 g/mol). (hindawi.com)
  • In the first part, the energy landscapes of the BLN-69 and G\={o}-69 model proteins are investigated using metric disconnectivity graph analysis, which incorporates both the kinetic and geometric structure of an energy landscape. (bham.ac.uk)
  • In addition, the antibody-antigen sandwich model structure was used to detect β-amyloid, which is a well-known biomarker of Alzheimer's disease. (mdpi.com)
  • The course comprises molecular biology of genes, proteins, multicomponent protein complexes, and other biomolecules that provide structure and perform the organism's functions. (lu.se)
  • In order to fully optimise the encapsulation system for a certain application, however, it is important to understand the effect of the encapsulated biomolecule on the lipid structure and vice versa. (lu.se)
  • The students are to acquire knowledge of chemical bonding, and molecular properties and how they relate to thermodynamics, temperature and interactions in solution. (lu.se)
  • Native SAD, exploiting the intrinsic S and P atoms of biomolecules, has become routine. (iucr.org)
  • Weakly bound, atomic and molecular, clusters have been the subject of many studies to investigate structures, dynamics and energetics of nano-scale objects, with the goal to understand the evolution of their properties from isolated atoms to the bulk solid. (lu.se)
  • Coarse-grained modeling, coarse-grained models, aim at simulating the behaviour of complex systems using their coarse-grained (simplified) representation. (wikipedia.org)
  • Coarse-grained models are widely used for molecular modeling of biomolecules at various granularity levels. (wikipedia.org)
  • A wide range of coarse-grained models have been proposed. (wikipedia.org)
  • He combines this with theoretical modelling of nanocomponents for photovoltaics and sub-wavelength focusing of light both by his own group and in collaborations. (lu.se)
  • He combines this with theoretical modelling of nanocomponents for photovoltaics and creating new architectures for light emitting diodes, breaking the limits of ray optics and avoiding the challenge of total internal reflection. (lu.se)
  • The challenges are at once scientific, medical and technological with, for example, the development of new molecular and subcellular imaging methods. (aviesan.fr)
  • As a result, NMR can be efficiently used to determine structures of entire complexes or of selected parts thereof, e.g. for fitting structures into low resolution models obtained by other methods, and for high-throughput screening applications. (bacatec.de)
  • As nanowires (NWs) gain momentum in biological applications, it is becoming increasingly important to understand the molecular interactions at these sophisticated interfaces. (lu.se)
  • Jesper Nygård has worked with biologists on interfacing nanowires with biomolecules and living cells. (lu.se)
  • Application areas range from molecular biology to astrophysics. (h-its.org)
  • This work is a first step towards physically realistic in silico whole-cell models that connect molecular with cellular biology. (elifesciences.org)
  • How biomolecules efficiently function in real biological environments with crowding and significant chemical and physical heterogeneity remains a fundamental question in biology ( Minton, 2001 ). (elifesciences.org)
  • Participants will acquire a sound overview and sophisticated problem-oriented skills in the course of this Summer School, which is organized by Prof. Paul Rösch and Dr. Stephan Schwarzinger from Lehrstuhl Biopolymere, Universität Bayreuth, Germany, and Prof. Peter E. Wright from the Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA. (bacatec.de)
  • To provide students with the opportunity to be exposed to the current state of understanding of the molecular biology of bacteria. (lu.se)
  • The students will gain an understanding of genetics concepts and molecular biology techniques by using them in the context of a research project. (lu.se)
  • The DMQ group uses stochastic mathematical models, high-performance computing, and hardware-aware computing to quantify the impact of uncertainties in large data sets. (h-its.org)
  • By employing mathematical models and experimental observations, physical chemists unlock a deeper understanding of nature's building blocks. (freescience.info)
  • Moreover, we investigate different compact molecular representations, based on atomic or bi-atomic substructures. (degruyter.com)
  • The proposed deep learning model will be set up to address the characterization of dynamic properties of protein-RNA interactions at the 3D level. (loria.fr)
  • Cp2TiCl2: Synthesis, Characterization, Modeling and Catalysis. (acs.org)
  • NMR is the only method currently available that can provide high resolution characterization of flexible biomolecules, information on transient interactions between biomolecules, and information on functionally-relevant molecular motions. (bacatec.de)
  • Cu(II) complexes with low molecular weight are functional superoxide-dismutase (SOD) models with superior reactive oxygen species (ROS) removal ability. (tus.ac.jp)
  • In this regard, low molecular weight Cu(II) complexes have gained importance as functional SOD models that exhibit high SOD activity. (tus.ac.jp)
  • We theorized that the resulting SOD-mimetic hybrid protein would improve the biocompatibility and stability of the functional SOD model Cu(II) complex," explains Dr. Nakane as the rationale behind their study. (tus.ac.jp)
  • However, creating a functional AI model is challenging. (bvsalud.org)
  • Our studies use experimental autoimmune encephalomyelitis (EAE) as a model to investigate pathological events related to Multiple Sclerosis. (utsa.edu)
  • Currently, molecular replacement with AlphaFold models often obviates the need for experimental phase evaluation. (iucr.org)
  • Collaborative investigations of photophysics, photochemistry and ultrafast dynamics in molecular and heterogeneous systems carried out together with experimental colleagues. (lu.se)
  • The experimental part focus on the model organisms, Bacillus subtilis , Escherichia coli and Streptomyces coelicolor . (lu.se)
  • Biomolecules, such as amino acids and proteins, which govern much of the biological processes in our bodies, are chiral as well. (lsu.edu)
  • The research interests of Professor Darve span across several domains, including machine learning for engineering, surrogate and reduced order modeling, stochastic inversing, anomaly detection for engineering processes and manufacturing, numerical linear algebra, high-performance and parallel computing, and GPGPU. (stanford.edu)
  • Membrane-mediated processes play a key role in many biological functions and supported lipid bilayers are excellent model systems for the study of membranes and membrane-integrated proteins. (lu.se)
  • be able to describe molecular genetic processes in bacteria. (lu.se)
  • Photoinduced processes in complex systems can be modeled as a sequence of events initiated by the absorption of a photon. (lu.se)
  • The need to understand how this initial event leads to higher ionization states and dynamic effects in complex systems such as biomolecules or nanostructured materials is motivated by biological processes and by possible light-harvesting applications. (lu.se)
  • A round-table discussion was held in Research Triangle Park, NC, on 11-12 February 1998, to develop a broader appreciation of the key processes and parameters required in developing nasal tissue dosimetry models. (cdc.gov)
  • The project team successfully tested their NBC model on a series of specific mathematical problems requiring a very large number of calculations. (europa.eu)
  • Detecting the handedness of dilute concentrations of biomolecules is a key step towards the early detection of many neurodegenerative disorders such as Alzheimer's, Huntington's, or Parkinson's disease," said LSU Chemical Engineering Associate Professor Kevin McPeak, lead author on the paper. (lsu.edu)
  • From materials science to biochemistry, physical chemists employ their expertise to explore chemical systems at the molecular level. (freescience.info)
  • Chemists have used computers for decades to model biomolecules such as proteins and DNA, says Loukas Petridis, an ORNL staff scientist. (doe.gov)
  • At the Institute of Molecular Biotechnology (IMBT) we focus on molecular aspects at the level of genes, RNA, proteins, cells, and organisms that are relevant in biotechnology. (boku.ac.at)
  • A validation of models for prediction of pathogenic variants in mismatch repair genes. (cdc.gov)
  • Then, a recurrent neural network is used to reconstruct the final fingerprints into actual molecular structures while maintaining their chemical validity. (nature.com)
  • As design tools for materials, they not only optimize the molecular structures but also provide hints for a promising chemical space by identifying genetic traits that favor the target properties while maintaining the unique genotypes of ancestors. (nature.com)
  • For complicated structures, such as those of biological macromolecules, suitable initial models are built to fit electron-density distributions from Fourier syntheses, which require phase angles as well as the diffraction amplitudes. (iucr.org)
  • Free energy is the most important thermodynamic quantity because the free-energy change associated with a molecular process determines whether the process can occur spontaneously under given thermodynamic boundary conditions. (tum.de)
  • As systems we study viruses, prokaryotes as well as eukaryotes, ranging from model organisms like E. coli to applications in Human. (boku.ac.at)
  • In aerobic organisms, reactive oxygen species (ROS), such as hydroxide (OH), singlet oxygen ( 1 O 2 ), hydrogen peroxide (H 2 O 2 ), and superoxide (O 2 - ) ions are produced during aerobic respiration, which causes serious oxidative damage to biomolecules in the body. (tus.ac.jp)
  • Abstract: Carbohydrates are incredibly diverse biomolecules that facilitate communication between cells and between organisms. (uci.edu)
  • These effects are expected to have broad implications for the in vivo functioning of biomolecules. (elifesciences.org)
  • These beneficial biological properties have been extensively studied in humans and animal models, both in vitro and in vivo . (hindawi.com)
  • Relating in vitro to in vivo exposures with physiologically-based tissue dosimetry and tissue response models. (cdc.gov)
  • While major improvements have been introduced with the breakthrough of artificial intelligence (AlphaFold2 [3]), predicting conformational dynamics of biomolecules is still challenging. (loria.fr)
  • The MCM group focuses on the interactions of biomolecules. (h-its.org)
  • Pauline's research focuses on building such models through a physics-informed learning based approach, taking advantage of the available measurements. (lu.se)
  • The student will learn how spectroscopy and models for intermolecular interactions can be used to understand basic properties of biomolecules such as proteins, DNA and membranes. (lu.se)
  • Producers Association (MPA), and Vinyl Acetate Toxicology Group (VATG), have spon- sored development of physiologically based pharmacokinetic (PBPK) models for nasal tis- sue dosimetry with, respectively, acrylic acid (AA), methyl methacrylate (MMA), and vinyl acetate (VA). These compounds cause lesions in nasal epithelial tissues and are clas- sified as "Category 1" gases within the U.S. EPA (1994) classification scheme. (cdc.gov)
  • The contributions of several disciplines--toxicology, engi- neering, and physiologically based pharmacokinetic ( PBPK) modeling--were evident in the discussions. (cdc.gov)
  • First, I will highlight how tools to detect glycan-protein interactions, validate binding sites, and generate precise animal models were used to uncover polysaccharide ligands for a mammalian orphan receptor that regulates vascular physiology. (uci.edu)
  • Molecular modeling to gather together data on the chemical, structural and dynamic properties of biomolecules. (aviesan.fr)
  • The discussions at the round table drew on these three case studies and several background presentations to assess the manner in which chemical-specific and mode-of-action data can be incorporated into nasal dosimetry models. (cdc.gov)
  • These models have been developed to gain a better understanding of both the physiologi- cal and anatomical characteristics of animal species and the physico- chemical characteristics of specific inhaled materials that determine the amounts of gases absorbed by tissues in various regions of the respiratory tract. (cdc.gov)
  • Conclusions: Object detection AI model in small bowel CE using YOLO v5 may provide effective and easy-to-understand reading assistance. (bvsalud.org)
  • Single cell sequencing combined with deep learning enables him to analyse and model differences between cells. (lu.se)
  • Increasing our knowledge of the molecular and structural bases of the living organism is only possible through combined approaches. (aviesan.fr)
  • This article outlines the presentations and topical areas discussed at the round table and notes recommenda- tions made by participants to extend models for nasal dosimetry and to develop improved data for modeling. (cdc.gov)
  • The round-table articles that are published separately in this issue and the discussions, captured in this overview, pro- vide a glimpse of the state of the science in nasal dosimetry modeling and a clear indica- tion of the growth of and continuing opportunities in this important research area. (cdc.gov)
  • The method employs deep learning models to extract the inherent knowledge from a database of materials and is used to effectively guide the evolutionary design. (nature.com)
  • Although the trial-and-error approach has generally been considered as the most acceptable way to develop new materials, computer-aided techniques are increasingly being used to enhance the efficiency and hit rate of molecular design 1 . (nature.com)
  • and self-assembly of biomolecules into machines and materials. (confex.com)
  • These chemicals are characterized by their low molecular weight and their ability to inhibit the progress of certain infections. (hindawi.com)
  • In recent years, there has been an increasing interest in applying dosim- etry models to chemicals, in addition to the criteria air pollutants,* in order to estimate dose in various portions of the respiratory tract. (cdc.gov)