Relevant Distances Research Articles

An Analytical Model for Resistance-Limited Recombination at Line Defects in Solar Cells

In this paper, one-dimensional analytical model is presented that reproduces lateral changes in p-n junction voltage as a result of recombination at line defects. The model takes into account the majority charge carrier transport in the emitter and in the base over a long distance (>1 mm) as induced by a line defect (for example, a metal finger, an edge, or any line-shaped region with a higher recombination rate). The model predicts the p-n junction voltage as a function of distance to the recombination center in one dimension. The model is compared with numerical device simulations using Quokka3 for two scenarios typical in current state-of-the-art solar cells. The deviation of the lateral p-n junction voltage is less than 1 mV for contact recombination and less than 4 mV for edge recombination. These results show that over the relevant distances, the carrier transport is almost purely resistive, validating the main hypothesis of this model. Such good agreement, and the corresponding compatibility with numerical device simulations, renders the model a useful tool for the interpretation of experimental results.

Advantages and limitation of using 2-D FE modelling for assessment of effect of mitigation measures for railway vibrations

This paper addresses mitigation measures against railway vibrations in soft soils by use of FE calculations. In order for calculation models to be used as design tools, it is essential that they are relatively easy to set up and have reasonably short computational times which would allow sensitivity and optimization analyses. It is therefore desirable to use two-dimensional (2D) models to the greatest possible extent. The focus of this paper is to investigate the advantages and limitation of using such models as engineering approach to study effect of countermeasures. The difference between 2D and three-dimensional (3D) calculation models, and the performance of absorbing boundary conditions are investigated. The study shows that 2D models provide satisfactory results as long as root mean square values are considered, the treated area is long compared to other relevant distances, and the results are primarily used to compare different mitigation measures. However, since geometrical attenuation is not correctly captured in 2D models, they should not be used to calculate absolute vibration values. In a presented case study, the effects of lime-cement columns under the track bed and as a vibration-reducing screen parallel to the track are calculated and compared. The study shows good effect of both mitigation measures in the low frequency range. To avoid structure-borne noise problems, it may be necessary to combine columns below track bed with mitigation measures effective at higher frequencies, such as rail pads or ballast mats.

Polymerization pattern characterization within a resin-based composite cured using different curing units at two distances.

To investigate the relationship of the irradiance-beam-profile areas from six different light-curing units (LCUs) with the degree of conversion (DC), microhardness (KH), and cross-link density (CLD) throughout a resin-based composite (RBC) cured at two clinically relevant distances, and to explore the correlations among them. A mapping approach was used to measure DC using micro-Raman spectroscopy, KH using a Knoop indentor on a hardness tester, and %KH reduction after ethanol exposure, as an indicator for CLD within a nano-hybrid RBC increment (n = 3) at various depths. These sample composites were cured from two distances while maintaining the radiant exposure, using six different light-curing units: one quartz-tungsten-halogen; two single and three multiple-emission-peak light-emitting-diode units. Irradiance beam profiles were generated for each LCU at both distances, and localized irradiance values were calculated. Points across each depth were analyzed using repeated measures ANOVA. Correlations across multiple specimen locations and associations between beam uniformity corresponding with polymerization measurements were calculated using linear mixed models and Pearson correlation coefficients. Significant non-uniform polymerization patterns occurred within the specimens at various locations and depths. At 2-mm curing distance, the localized DC = 52.7-76.8%, KH = 39.0-66.7kg/mm2, and %KH reduction = 26.7-57.9%. At 8-mm curing distance, the localized DC = 50.4-78.6%, KH = 40.3-73.7kg/mm2, and %KH reduction = 28.2-56.8%. The localized irradiance values were weakly correlated with the corresponding DC, KH, and %KH reduction, with only a few significant correlations (p < 0.05). Although significant differences were observed at each depth within the specimens, the localized irradiance values for all LCUs did not reflect the polymerization pattern and did not seem to have a major influence on polymerization patterns within the RBC, regardless of the curing distance. Commonly used LCUs do not produce uniform polymerization regardless of the curing distance, which may contribute to the risk of RBC fracture.

A 2.6‐g sound and movement tag for studying the acoustic scene and kinematics of echolocating bats

Abstract To study sensorimotor behaviour in wild animals, it is necessary to synchronously record the sensory inputs available to the animal, and its movements. To do this, we have developed a biologging device that can record the primary sensory information and the associated movements during foraging and navigating in echolocating bats. This 2.6‐g tag records the sonar calls and echoes from an ultrasonic microphone, while simultaneously sampling fine‐scale movement in three dimensions from wideband accelerometers and magnetometers. In this study, we tested the tag on an European noctula Nyctalus noctula during target approaches and on four big brown bats Eptesicus fuscus during prey interception in a flight room. We show that the tag records both the outgoing calls and echoes returning from objects at biologically relevant distances. Inertial sensor data enables the detection of behavioural events such as flying, turning, and resting. In addition, individual wing‐beats can be tracked and synchronized to the bat's sound emissions to study the coordination of different motor events. By recording the primary acoustic flow of bats concomitant with associated behaviours on a very fine time‐scale, this type of biologging method will foster a deeper understanding of how sensory inputs guide feeding behaviours in the wild.

340 Convection-Enhanced Delivery of Macromolecules to the Brain Using Electrokinetic Transport

Electrokinetic transport in brain tissue represents the movement of molecules due to an applied electric field and the interplay between the electrophoretic and electroosmotic velocities that are developed. This dissertation provides a framework for understanding electrokinetic transport and how it may be utilized for short-distance ejections, relevant to capillary iontophoresis, and long-distance infusions, for the clinical management of malignant brain tumors as a novel convection-enhanced drug delivery system.In particular, electrokinetic transport was first analyzed in a series of poly(acrylamide-co-acrylic acid) hydrogels that demonstrated varying electroosmotic velocities. Moreover, a hydrogel was synthesized to mimic the electrokinetic properties of organotypic hippocampal slice cultures (OHSC), as a surrogate for brain tissue. Short- and long-distance capillary infusions of molecules into the hydrogels and OHSC provided a framework to understand the relevant phenomena, such as the effect of varying the capillary tip size, applied electrical current, ζ-potential of the capillary or the outside matrix, infusion time, tortuosity, and properties of the solute (including molecular weight and electrophoretic mobility). Control of the directional transport of molecules was also demonstrated over a distance of several hundred micrometers to millimeters. Finally, electrokinetic infusions were conducted in vivo in the adult rat brain, with results compared to those of pressure-driven infusions.The experiments and results described in this dissertation provide a foundation for further development, by presenting a methodical means to increase the ejection profile and attain clinically relevant penetration distances while minimizing adverse effects to the brain tissue, including from the electric field itself. The rate of electrokinetic transport is greater than the rate of diffusion, and therefore it represents a novel form of convection-enhanced drug delivery system.

Directional Distance Functions in DEA with Optimal Endogenous Directions

This paper is concerned with optimal directions in the directional distance function in data envelopment analysis. It is shown that the vector pointing in the direction that minimizes the Euclidean distance between the input–output vector (Xo, Yo) and the efficient frontier, the input isoquant reflecting output Yo, or the output isoquant reflecting input Xois optimal, because the corresponding vector of virtual multipliers defines the relative prices that maximize profit, cost, or revenue efficiency. The associated efficiency indicator is a value measure of technical efficiency in difference form with the Euclidean distance between (Xo, Yo) and the efficient frontier, the Yoinput isoquant, or the Xooutput isoquant as an equivalent directional distance quantity indicator. A linear combinatorial optimization program for computing the relevant value indicators of technical efficiency in multiplier space or the equivalent quantity indicators in terms of the relevant Euclidean distances is developed. A nonlinear and nonconvex optimization model for an estimation of the relevant value indicator of efficiency in multiplier space is also developed. Preliminary computational results are reported.

Positional uncertainty in optical-based metrology systems in large volume manufacturing

&lt;p class="Abstract"&gt;&lt;span lang="EN-US"&gt;Modern manufacturing increasingly utilizes automated systems for component positioning and assembly and a vital aspect of autonomous precision manufacturing is large volume metrology. One popular approach uses light rays, which travel through the volume of air, to calculate the position of an object of interest. These optical-based metrology systems such as photogrammetry and laser tracking are crucial in improving the accuracy and quality associated with robotic assembly. However, in an industrial setting, these positional measurement systems give rise to uncertainties which can in many instances be greater than the required tolerances. One source of this uncertainty is light refraction due (in part) to temperature fluctuations in the air. This paper will describe how COMSOL Multiphysics can be used to create simulated data with complete ground truth on the refractive index field in the volume, and will discuss the measurement uncertainties associated with these simulations. Over industry relevant distances (tens of metres) the uncertainty in the position measurement due to light refraction is of the order of a millimetre.&lt;/span&gt;&lt;/p&gt;

Colloidal crystal order and structure revealed by tabletop extreme ultraviolet scattering and coherent diffractive imaging.

Colloidal crystals with specific electronic, optical, magnetic, vibrational properties, can be rationally designed by controlling fundamental parameters such as chemical composition, scale, periodicity and lattice symmetry. In particular, silica nanospheres -which assemble to form colloidal crystals- are ideal for this purpose, because of the ability to infiltrate their templates with semiconductors or metals. However characterization of these crystals is often limited to techniques such as grazing incidence small-angle scattering that provide only global structural information and also often require synchrotron sources. Here we demonstrate small-angle Bragg scattering from nanostructured materials using a tabletop-scale setup based on high-harmonic generation, to reveal important information about the local order of nanosphere grains, separated by grain boundaries and discontinuities. We also apply full-field quantitative ptychographic imaging to visualize the extended structure of a silica close-packed nanosphere multilayer, with thickness information encoded in the phase. These combined techniques allow us to simultaneously characterize the silica nanospheres size, their symmetry and distribution within single colloidal crystal grains, the local arrangement of nearest-neighbor grains, as well as to quantitatively determine the number of layers within the sample. Key to this advance is the good match between the high harmonic wavelength used (13.5nm) and the high transmission, high scattering efficiency, and low sample damage of the silica colloidal crystal at this wavelength. As a result, the relevant distances in the sample - namely, the interparticle distance (≈124nm) and the colloidal grains local arrangement (≈1μm) - can be investigated with Bragg coherent EUV scatterometry and ptychographic imaging within the same experiment simply by tuning the EUV spot size at the sample plane (5μm and 15μm respectively). In addition, the high spatial coherence of high harmonics light, combined with advances in imaging techniques, makes it possible to image near-periodic structures quantitatively and nondestructively, and enables the observation of the extended order of quasi-periodic colloidal crystals, with a spatial resolution better than 20nm. In the future, by harnessing the high time-resolution of tabletop high harmonics, this technique can be extended to dynamically image the three-dimensional electronic, magnetic, and transport properties of functional nanosystems.

Partial discharge detection for characterizing cable insulation under low and medium vacuum conditions

Design of cables for operation in a low pressure environment is challenging, when applications also demand lightweight and flexibility, and material choice is restricted. The operating pressures in combination with relevant distances, can be situated near gas breakdown and cause partial discharges, making long-term damage conceivable. An experimental setup is developed, based on partial discharge detection in a vacuum system, to characterize the partial discharge inception voltage of three coaxial cable designs in an argon and nitrogen environment at controllable pressure. In order to cope with outgassing behavior, a lumped element model is presented to simulate the internal pressure distribution along the cable as a function of settling time. Microscopic cross sections of the cables are analysed with electrostatic voltage simulations. Using scaled Paschen curves, expected partial discharge inception is determined and compared with measurements. Quantifying cable performance, in terms of minimum PD inception voltage and pressure, in relation to its design is feasible, but also deviations occur which are discussed.

Soft spot: the important zone at the standard posterior portal of shoulder arthroscopy

Background/aim: The localization of the standard posterior portal of shoulder arthroscopy and landmarks mentioned in the literature are unclear. The purpose of this prospective cadaveric study was to determine the localization of the standard posterior portal and its distance to the neural structures. Materials and methods: One fresh frozen and 10 formalin-fixed adult cadaveric shoulders were dissected. In the beach chair position, a 5-mm trocar was placed anteroposteriorly from the superior edge of the subscapularis muscle, superior to the tip of the coracoid process and tangent to the glenoid. The relevant distances of the posterior exit point were measured. Results: In all specimens, the exit point was a triangular fibrous area, between the posterior and lateral parts of the deltoid. Medial and inferior distances of the trocar to the posterolateral tip of the acromion were 1.88 ± 0.53 cm and 1.35 ± 0.34 cm and distances to the axillary and suprascapular nerves were 4.54 ± 1.08 cm and 2.54 ± 0.85 cm, respectively. Conclusion: The most important finding of this study was the superficial localization of the soft spot between the posterior and lateral parts of deltoid.

L'Union Fait La Force? Evidence for Wage Discrimination in Firms with High Diversity

Measuring the economic impact of coworkers from different countries of origin sparked intense scrutiny in labor economics, albeit with an uncomfortable methodological limitation. Most attempts involved metrics that eliminate most of the economically relevant distances among different countries of origin. The typical examples of such metrics are diversity indicators that divide the firm’s workforce into blacks and whites, foreigners and natives, non-Europeans and Europeans, etc. We propose an entirely novel approach. It is based on the conversion of the qualitative information on individuals’ countries of origin into an aggregate firm-level diversity indicator, built on the United Nations Development Programme’s Human Development Index (HDI), a standard harmonized measure of cross-country variations that is available for virtually all the countries in the world. By resorting to rich matched employer-employee panel data for Belgium, we use this new aggregate measure to estimate state-of-the-art firm-level wage equations, which control for a wide range of observable and time-invariant unobservable factors, including variations in labor productivity between firms and within firms over time. Our results suggest that the majority of firms do not discriminate against foreigners. Yet, we find that firms with high diversity largely discriminate against them. The wage discrimination in high-diversity firms could be alleviated through a stronger presence of collective bargaining and/or efforts to de-cluster foreigners from low-HDI countries in these firms.

Abstract

&lt;p&gt;Higher actuator voltages are required for future generation lithography machines to increase productivity. The operating pressures in combination with relevant insulation distances, can be situated near gas breakdown and cause partial discharge activity, making long-term damage conceivable. High voltage cone-shape connectors with pliable insulation can be applied for the low and medium vacuum range. However, materials and space are restricted making a cone shaped connector not ideal. In this paper, a flat connector concept is presented with a pliable insulation material allowed to be used for the aforementioned application. The permittivity of this material is measured and simulation results of the connector reveal critical design points. A prototype connector is made and its partial discharge inception voltage is characterized for the low and medium vacuum range. The results are discussed and compared with simulations.&lt;/p&gt;

Investigation of a Flat Connector Concept Potential for Low and Medium Vacuum Conditions

Higher actuator voltages are required for future generation lithography machines to increase productivity. The operating pressures in combination with relevant insulation distances, can be situated near gas breakdown and cause partial discharge activity, making long-term damage conceivable. High voltage cone-shape connectors with pliable insulation can be applied for the low and medium vacuum range. However, materials and space are restricted making a cone shaped connector not ideal. In this paper, a flat connector concept is presented with a pliable insulation material allowed to be used for the aforementioned application. The permittivity of this material is measured and simulation results of the connector reveal critical design points. A prototype connector is made and its partial discharge inception voltage is characterized for the low and medium vacuum range. The results are discussed and compared with simulations.

Does an inter-flaw length control the accuracy of rupture forecasting in geological materials?

Multi-scale failure of porous materials is an important phenomenon in nature and in material physics – from controlled laboratory tests to rockbursts, landslides, volcanic eruptions and earthquakes. A key unsolved research question is how to accurately forecast the time of system-sized catastrophic failure, based on observations of precursory events such as acoustic emissions (AE) in laboratory samples, or, on a larger scale, small earthquakes. Until now, the length scale associated with precursory events has not been well quantified, resulting in forecasting tools that are often unreliable. Here we test the hypothesis that the accuracy of the forecast failure time depends on the inter-flaw distance in the starting material. We use new experimental datasets for the deformation of porous materials to infer the critical crack length at failure from a static damage mechanics model. The style of acceleration of AE rate prior to failure, and the accuracy of forecast failure time, both depend on whether the cracks can span the inter-flaw length or not. A smooth inverse power-law acceleration of AE rate to failure, and an accurate forecast, occurs when the cracks are sufficiently long to bridge pore spaces. When this is not the case, the predicted failure time is much less accurate and failure is preceded by an exponential AE rate trend. Finally, we provide a quantitative and pragmatic correction for the systematic error in the forecast failure time, valid for structurally isotropic porous materials, which could be tested against larger-scale natural failure events, with suitable scaling for the relevant inter-flaw distances.

Using anatomical landmark to avoid phrenic nerve injury during balloon-based procedures in atrial fibrillation patients.

Atrial fibrillation (AF) is an arrhythmia which affects as many as 2.7 million Americans. AF should be treated, because it can lead to a four-to-fivefold increased risk of experiencing a stroke. The American College of Cardiology/American Heart Association guidelines for the treatment of drug refractory and symptomatic paroxysmal AF denote catheter ablation as the standard of care. The newest ablation treatment, cryoballoon, uses a cold balloon tip. The biggest risk factor associated with the cryoballoon ablation is phrenic nerve injury (PNI). The purpose of this study is to measure relevant distances from specific landmarks to the right phrenic nerve (RPN) to create a safe zone for physicians. Using 30 cadaveric specimens, we measured laterally from the right superior pulmonary vein orifice (RSPV) to the RPN at the level of the sixth thoracic vertebra and laterally from the lateral border of the sixth thoracic vertebral body (T6) to the RPN. The depth and width of the left atrium (LA) were also measured to establish a cross-sectional area of the LA. The cross-sectional area of the LA was then correlated with the averaged measurements to see if the area of the LA could be a predictor of the location of the RPN. The average distance from the RPN-RSPV was 9.6mm (range 4.3-18.8mm). The average RPN-T6 distance was 30.6mm (range 13.7-49.9mm). There was a non-significant trend that suggests as the size of the LA increases, the measured distances also increased. Using the lateral border of the sixth thoracic vertebra as a landmark, which can be viewed under fluoroscopy during the procedure, physicians can triangulate the distance to the RSPV and determine the approximate position of the RPN. Furthermore, physicians can perform a preoperative echocardiogram to determine the size of the LA to assist in determining the position of the RPN with the hopes of avoiding injury to the RPN.

Microfluidic co-culture platform for investigating osteocyte-osteoclast signalling during fluid shear stress mechanostimulation

Bone cells exist in a complex environment where they are constantly exposed to numerous dynamic biochemical and mechanical stimuli. These stimuli regulate bone cells that are involved in various bone disorders, such as osteoporosis. Knowledge of how these stimuli affect bone cells have been utilised to develop various treatments, such as pharmaceuticals, hormone therapy, and exercise. To investigate the role that bone loading has on these disorders in vitro, bone cell mechanotransduction studies are typically performed using parallel plate flow chambers (PPFC). However, these chambers do not allow for dynamic cellular interactions among different cell populations to be investigated. We present a microfluidic approach that exposes different cell populations, which are located at physiologically relevant distances within adjacent channels, to different levels of fluid shear stress, and promotes cell-cell communication between the different channels. We employed this microfluidic system to assess mechanically regulated osteocyte-osteoclast communication. Osteoclast precursors (RAW264.7 cells) responded to cytokine gradients (e.g., RANKL, OPG, PGE-2) developed by both mechanically stimulated (fOCY) and unstimulated (nOCY) osteocyte-like MLO-Y4 cells simultaneously. Specifically, we observed increased osteoclast precursor cell densities and osteoclast differentiation towards nOCY. We also used this system to show an increased mechanoresponse of osteocytes when in co-culture with osteoclasts. We envision broad applicability of the presented approach for microfluidic perfusion co-culture of multiple cell types in the presence of fluid flow stimulation, and as a tool to investigate osteocyte mechanotransduction, as well as bone metastasis extravasation. This system could also be applied to any multi-cell population cross-talk studies that are typically performed using PPFCs (e.g. endothelial cells, smooth muscle cells, and fibroblasts).

Iodinated Meroditerpenes from a Red Alga Callophycus sp.

Unique iodine-containing meroditerpenes iodocallophycoic acid A (1) and iodocallophycols A-D (2-5) were discovered from the Fijian red alga Callophycus sp. Because flexibility of the molecular skeleton impaired full characterization of relative stereochemistries by NMR spectroscopy, a DFT-based theoretical model was developed to derive relevant interproton distances which were compared to those calculated from NOE measurements, yielding the relative stereochemistries. The correct 2S,6S,7S,10S,14S enantiomers were then identified by comparison of theoretical and experimental ECD spectra. Biological activities of these iodinated and brominated meroditerpenes and additional new, related bromophycoic acid F (6) and bromophycoic acid A methyl ester (7), were evaluated for relevant human disease targets. Iodocallophycoic acid A (1) showed moderate antibiotic activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VREF) with MIC values of 1.4 and 2.2 μg mL-1, respectively. It also potentiated the anti-MRSA activity of oxacillin in a synergistic fashion, resulting in an 8-fold increase in oxacillin potency, for a MIC of 16 μg mL-1.

GAIA PARALLAX ZERO POINT FROM RR LYRAE STARS

Like Hipparcos, Gaia is designed to give absolute parallaxes, independent of any astrophysical reference system. And indeed, Gaia's internal zero-point error for parallaxes is likely to be smaller than any individual parallax error. Nevertheless, due in part to mechanical issues of unknown origin, there are many astrophysical questions for which the parallax zero-point error <TEX>${\sigma}({\pi}_0)$</TEX> will be the fundamentally limiting constraint. These include the distance to the Large Magellanic Cloud and the Galactic Center. We show that by using the photometric parallax estimates for RR Lyrae stars (RRL) within 8kpc, via the ultra-precise infrared period-luminosity relation, one can independently determine a hyper-precise value for <TEX>${\pi}_0$</TEX>. Despite their paucity relative to bright quasars, we show that RRL are competitive due to their order-of-magnitude improved parallax precision for each individual object relative to bright quasars. We show that this method is mathematically robust and well-approximated by analytic formulae over a wide range of relevant distances.

The Evolution of Strain Typing in the Mycobacterium tuberculosis Complex.

Tuberculosis (TB) is a contagious disease with a complex epidemiology. Therefore, molecular typing (genotyping) of Mycobacterium tuberculosis complex (MTBC) strains is of primary importance to effectively guide outbreak investigations, define transmission dynamics and assist global epidemiological surveillance of the disease. Large-scale genotyping is also needed to get better insights into the biological diversity and the evolution of the pathogen. Thanks to its shorter turnaround and simple numerical nomenclature system, mycobacterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR) typing, based on 24 standardized plus 4 hypervariable loci, optionally combined with spoligotyping, has replaced IS6110 DNA fingerprinting over the last decade as a gold standard among classical strain typing methods for many applications. With the continuous progress and decreasing costs of next-generation sequencing (NGS) technologies, typing based on whole genome sequencing (WGS) is now increasingly performed for near complete exploitation of the available genetic information. However, some important challenges remain such as the lack of standardization of WGS analysis pipelines, the need of databases for sharing WGS data at a global level, and a better understanding of the relevant genomic distances for defining clusters of recent TB transmission in different epidemiological contexts. This chapter provides an overview of the evolution of genotyping methods over the last three decades, which culminated with the development of WGS-based methods. It addresses the relative advantages and limitations of these techniques, indicates current challenges and potential directions for facilitating standardization of WGS-based typing, and provides suggestions on what method to use depending on the specific research question.

Collision-kerma conversion between dose-to-tissue and dose-to-water by photon energy-fluence corrections in low-energy brachytherapy

The AAPM TG-43 brachytherapy dosimetry formalism, introduced in 1995, has become a standard for brachytherapy dosimetry worldwide; it implicitly assumes that charged-particle equilibrium (CPE) exists for the determination of absorbed dose to water at different locations, except in the vicinity of the source capsule. Subsequent dosimetry developments, based on Monte Carlo calculations or analytical solutions of transport equations, do not rely on the CPE assumption and determine directly the dose to different tissues. At the time of relating dose to tissue and dose to water, or vice versa, it is usually assumed that the photon fluence in water and in tissues are practically identical, so that the absorbed dose in the two media can be related by their ratio of mass energy-absorption coefficients. In this work, an efficient way to correlate absorbed dose to water and absorbed dose to tissue in brachytherapy calculations at clinically relevant distances for low-energy photon emitting seeds is proposed. A correction is introduced that is based on the ratio of the water-to-tissue photon energy-fluences. State-of-the art Monte Carlo calculations are used to score photon fluence differential in energy in water and in various human tissues (muscle, adipose and bone), which in all cases include a realistic modelling of low-energy brachytherapy sources in order to benchmark the formalism proposed. The energy-fluence based corrections given in this work are able to correlate absorbed dose to tissue and absorbed dose to water with an accuracy better than 0.5% in the most critical cases (e.g. bone tissue).