Unpredictable Errors Research Articles

Different Effects of Bromodeoxyuridine and [3H]Thymidine Incorporation into DNA on Cell Proliferation, Position, and Fate

As markers of DNA synthesis, [(3)H]thymidine ([(3)H]dT) and the later developed analog bromodeoxyuridine (BrdU) have revolutionized our ability to identify dividing cells and follow their fate in various tissues, including the nervous system. However, the effect of the incorporation of these molecules into DNA on cell proliferation, migration, differentiation, and function is not fully understood. Here, we compare the number and distribution of labeled cells in the cerebral cortex of postnatal macaque monkeys exposed to either [(3)H]dT or BrdU as embryos. The large size and prolonged brain development in this species allows higher resolution of cellular events and more accurate discrimination between the two methods. Our analysis revealed substantial differences in the number and distribution of labeled cells. The data indicate that random incorporation of the thymidine analog BrdU into the genes of dividing cells makes the fate of postmitotic neurons more prone to unpredictable errors than the incorporation of the more natural DNA constituent nucleotide [(3)H]dT. These findings have implications for the interpretation of results obtained by BrdU as an index of the number of neurons produced, and their migration, placement, subsequent connectivity, function, and survival.

Automated Model Synchronization: A Case Study on UML with Maude

Design specifications of software-intensive systems involve models that have been defined with different modelling languages for different purposes. Hence, a specification can be seen as the description of a system from multiple viewpoints, each providing domain-specific constructs for modelling the system in a more precise way. Such heterogeneity of models can jeopardize the consistency of the specification, because updates in one viewpoint may cause unpredictable design errors in other viewpoints, which can then be transferred to the implementation. OMG’s Meta-Object Facility enhances the automation of the model consistency management by providing a uniform format for different modelling languages. In this paper, we illustrate a technique, based on rewriting logic and on strategies for finding inconsistencies in MOF-based heterogeneous specifications and for resolving them in an automated way.

Gene-therapy enzymes make unpredicted errors

Techniques show mistakes of 'highly specific' molecular tools.

Evaluating the impacts of dynamic reconfiguration on the QoS of running systems

A major challenge in dynamic reconfiguration of a running system is to understand in advance the impact on the system's Quality of Service (QoS). For some systems, any unexpected change to QoS is unacceptable. In others, the possibility of dissatisfaction increases due to the impaired performance of the running system or unpredictable errors in the resulting system. In general it is difficult to choose a reasonable reconfiguration approach to satisfy a particular domain application. Our investigation on this issue for dynamic approaches is four-fold. First, we define a set of QoS characteristics to identify the evaluation criteria. Second, we design a set of abstract reconfiguration strategies bringing existing and new approaches into a unified evaluation context. Third, we design a reconfiguration benchmark to expose a rich set of QoS problems. Finally, we test the reconfiguration strategies against the benchmark and evaluate the test results. The analysis of acquired results helps to understand dynamic reconfiguration approaches in terms of their impact on the QoS of running systems and possible enhancements for newer QoS capability.

Generalization of the Heat Transfer Coefficient Concept for System Simulation

Large progress has been realized in modeling conduction heat transfer problems over the past decade by the introduction of high performance compact thermal models (CTMs) mainly developed for thermal design of complicated electronic systems. The objective of this paper is to generalize these advances to convective heat transfer. A new convective CTM is proposed, which offers many advantages over the traditional approach using the heat transfer coefficient (HTC). The latter is simply a zeroth order CTM. The HTC is quite handy and simple, but with unpredictable errors. It can be suitable for hand calculations of simple systems giving rather crude estimates. For a higher precision, users have no other option than time consuming 3D simulations. For large systems, in terms of number of components, 3D simulations can be rapidly impractical. The CTM bridges the gap between both approaches going gradually from “HTC” levels (low precision and calculations time) at the zeroth order, to 3D simulation precision and computing time levels at large orders. Fortunately, like for conduction, a CTM of order of few tens quickly approaches 3D simulation precision levels, while keeping computation time significantly lower than 3D simulation. Moreover, the CTM approach solves conjugate heat transfer problems in a quite elegant way. A “black box” model, developed for fluid domain alone, can be easily combined with classical CTM conduction models to generate good precision predictions for any combination of fluid/solid domains.

Dissociated roles of the anterior cingulate cortex in reward and conflict processing as revealed by the feedback error-related negativity and N200

The reinforcement learning theory of the error-related negativity (ERN) holds that the impact of reward signals carried by the midbrain dopamine system modulates activity of the anterior cingulate cortex (ACC), alternatively disinhibiting and inhibiting the ACC following unpredicted error and reward events, respectively. According to a recent formulation of the theory, activity that is intrinsic to the ACC produces a component of the event-related brain potential (ERP) called the N200, and following unpredicted rewards, the N200 is suppressed by extrinsically applied positive dopamine reward signals, resulting in an ERP component called the feedback-ERN (fERN). Here we demonstrate that, despite extensive spatial and temporal overlap between the two ERP components, the functional processes indexed by the N200 (conflict) and the fERN (reward) are dissociable. These results point toward avenues for future investigation.

Drizzle: Cooperative Symbol-Level Network Coding in Multichannel Wireless Networks

Errors are inherently present in unreliable wireless channels. The primary challenge in designing error-control protocols in the medium-access control (MAC) or physical layer is to effectively maximize achievable throughput in wireless networks, even when unpredictable and time-varying errors exist. Network coding has successfully been applied to improve throughput in IEEE 802.11-based wireless networks with a shared broadcast channel. In state-of-the-art physical-layer designs in multichannel wireless networks [such as IEEE 802.16 Worldwide Interoperability for Microwave Access (WiMAX)], however, the convenience of a shared wireless broadcast channel to perform opportunistic listening no longer exists, and hybrid automatic repeat request (HARQ) is the predominant error-control protocol in the physical layer, rather than plain automatic repeat request in IEEE 802.11 MAC. Would network coding be well employed in multichannel wireless networks and able to bring further improvements over HARQ? This paper proposes Drizzle, which is a new solution to maximizing throughput with the presence of errors, which takes advantage of network coding at the symbol level in multichannel wireless networks. By operating at the symbol level and using soft-decision values, we show that Drizzle is able to exploit both time and cooperative diversity in realistic multichannel wireless networks, to adapt to time-varying and bursty channel errors, and to efficiently collect as many correct symbols as possible at the receiver.

Management Forecasts and the Market’s Earnings Expectations

This study investigates the relation between management forecasts and earnings expectations. Whereas the extant literature typically associates management forecasts with analysts’ forecasts, a proxy for the market’s earnings expectations, this study decomposes analysts’ forecasts into errors that can be predicted on an out-of-sample basis and into residual, unpredicted forecasts that better proxy for earnings expectations. I show that firms’ propensity to issue management forecasts is related to unpredicted errors in analysts’ forecasts that were issued prior to the management forecast, but do not find evidence of an association with analysts’ predictable errors. In addition, the market puts less weight on analysts’ predictable forecast errors when it reacts to the news in management earnings forecasts. Results are robust to the method used to predict analysts’ forecast errors and to controls for selection bias.

Prior NLOS Measurement Correction for Positioning in Cellular Wireless Networks

A mobile station (MS) location can be estimated from the measurement of the time of arrival of the signals that travel between each base station and the MS. In this scenario, the existence of non-line-of-sight (NLOS) propagation paths has been considered to be the main drawback to achieve high precision in positioning, since NLOS propagation introduces large and unpredictable errors in the time estimates that are obtained from the measurements. In this paper, we propose a new technique, called prior NLOS measurement correction (PNMC), to effectively correct the measurements from NLOS propagation in a previous stage to the positioning process. PNMC is based on a statistical processing of a record of measurements taken over a time window. This processing relies on the statistical estimate of the NLOS measurement ratio present in our record. This estimate is used to range the NLOS recorded measurements into segments. Finally, the correction is carried out by subtracting the expected NLOS errors for each segment. Several simulations have been conducted to show the increase in accuracy obtained by the usage of PNMC and the great improvement that this prior measurement correction means to subsequent wireless location and positioning techniques.

Determination of the prescription dose for biradionuclide permanent prostate brachytherapy

A model based on the linear quadratic model that has been corrected for repopulation, sublethal cell damage repair, and RBE effect has been used to determine the prescription dose for prostate permanent brachytherapy using seeds loaded with a mixture of 103Pd and 125I or a mixture of 103Pd and 131Cs. The prescription dose was determined by comparing the tumor cell survival fractions between the considered biradionuclide seed implant and one monoradionuclide seed implant chosen from 103Pd, 125I, and 131Cs. Prostate edema is included in the model. The influence of the value of the radiobiological parameters and RBE were also investigated. Two mixtures of radionuclides were considered: 103Pd0.75-125I0.25 and 103Pd0.25-131Cs0.75, where the subscripts indicate the fractions of total initial internal activity in the biradionuclide seed. These fractions were selected in order to obtain a dose distribution that lies between that of 103Pd and 125I/131Cs. As expected, the computed prescription dose values are dependent on the model parameters (edema half-life and magnitude, radiobiogical parameters, and RBE). The radionuclide used as a benchmark also has a strong impact on the derived prescribed dose. The large uncertainties in the radiobiological parameters and RBE values produce big errors in the computed prescribed dose. Averaged over the range of all the parameters and depending on the radionuclide used as a benchmark (in subscript), the derived prescription dose for the first mixture (PdI) would be: D(PdI)(Pd)=142(+15)(-16) Gy and D(PdI)(I)=142(+6)(-8) Gy; and D(PdCs)(Pd)=128(+13)(-13) Gy and D(PdCs)(Cs)=115(+6)(-7) Gy for the PdCs mixture. The uncertainties could be reduced if the radiobiological parameters and RBE value were known more accurately. However, as edema characteristics are patient dependent and can be obtained only after the treatment, an unpredictable error is unavoidable.

WE-E-AUD A-01: Controlling the Impact of Intensity Modulation When Treating Moving Targets with Dynamic IMRT

Purpose: The treatment of moving targets using dynamic IMRT can result in dosimetric effects that have a predictable component (dose blurring) and an unpredictable component (interplay between organ motion and leaf motion). We investigate the impact of the intensity modulation on the unpredictable component. Method and Materials: Software was written to simulate MLCs moving across a moving target using dose distributions exported from Eclipse. The dose distribution delivered to a static target was blurred with the target motion to give the expected dose distribution. Dose errors were calculated by comparing the dose delivered to a moving target with the expected dose distribution. The impact of the intensity modulation (1:1 to 6:1) on the maximum dose error was investigated for a wide range of MLC sequences and target motion. MLC sequences were identified which kept dose variations within 10% of the expected dose. Results were confirmed experimentally by measuring the dose delivered to an ion chamber array in a moving phantom. Results: The maximum dose error increases with increasing intensity modulation. Dose errors also increase with a decrease in the following parameters: target period, target amplitude, MLC separation and MLC speed. Simple rules were developed to determine whether a planned fluence / MLC sequence will give a dose error larger than 10%. If the MLC speed is restricted to 0.1cm/sec and target period ⩽6sec, then the maximum daily dose error is always less than 10% for all levels of intensity modulation. For some combinations of intensity modulation and MLC sequences, faster MLC speeds are acceptable depending on details of the MLC parameters and target motion. Conclusion: Intensity modulation as high as 6:1 can be used when treating moving targets with dynamic IMRT, but the MLC speed must be carefully restricted if unpredictable and large dose errors are to be avoided.

The use of fundamental frequency information by cochlear implant patients with residual low‐frequency hearing

Recent studies have demonstrated significant benefits of complementing the electric hearing provided by a cochlear implant (CI) with residual low‐frequency acoustic hearing. It has been suggested that the benefit of low‐frequency hearing (<250 Hz) is due to improved representation of fundamental frequency (F0). It was hypothesized that removing F0 information would negatively impact speech perception in bimodal CI patients (EAS) more so when they are using both modes of perception. It was further hypothesized that these patients' more effective use of F0 information would result in higher intelligibility scores and less unpredicted lexical boundary errors (LBEs) in a speech transcription task. Six EAS patients transcribed normal and F0‐flattened phrases. Results indicate EAS patients demonstrated a significant benefit from the residual low‐frequency acoustic hearing and perform better in this mode. Five of the six EAS patients were able to transcribe the normal phrases with greater accuracy than the flat F0 phrases in both conditions. These patients correctly parsed lexical boundaries and transcribed phonemic targets with greater accuracy in the bimodal condition. These results demonstrate the importance of pitch and low frequency spectral information in the perception of speech.

Interferometry measurement of protein concentration evolution during crystallization and dissolution with improved reliability and versatility

Interferometry is a widely used technique for real-time monitoring of concentration variation during processes in a solution like crystal growth and dissolution. This paper reports a protein concentration measurement system using a conventional Mach–Zehnder interferometer that allows monitoring the time course evolution of the protein concentration distribution during the processes of crystallization or dissolution. The demonstrated method showed improved reliability and versatility in that it (1) enables measurements under versatile temperature conditions and (2) eliminates the unpredictable errors caused by the environmental disturbances. The measurement system described in this paper can also be applied in measurements in other solution systems.

An Adaptive Multipath Mitigation Filter for GNSS Applications

Global navigation satellite system (GNSS) is designed to serve both civilian and military applications. However, the GNSS performance suffers from several errors, such as ionosphere delay, troposphere delay, ephemeris error, and receiver noise and multipath. Among these errors, the multipath is one of the most unpredictable error sources in high-accuracy navigation. This paper applies a modified adaptive filter to reduce code and carrier multipath errors in GPS. The filter employs a tap-delay line with an Adaline network to estimate the direction and the delayed-signal parameters. Then, the multipath effect is mitigated by subtracting the estimated multipath effects from the processed correlation function. The hardware complexity of the method is also compared with other existing methods. Simulation results show that the proposed method using field data has a significant reduction in multipath error especially in short-delay multipath scenarios.

GIS-based Watershed Management Modeling for Surface Runoff Calculation in Tatara River Basin, Japan

In the past few decades when Geographical Information System (GIS) technology was not fully developed in practical use, watershed delineation work used to be conducted manually by hydrologists based on topographic maps. The work was a tedious operation, since it had to be done repeatedly in similar manner for each basin or sub‐basin of interest, and its process always left some unpredicted errors. Nowadays, GIS software is being upgraded regularly with powerful tools responding to the needs of users in different fields. In the present study, to find a simple hydrological solution for a basin (Tatara River basin), an extension tool (ArcHydro) of a well‐known GIS software (ArcGIS) was essentially used for simulations of elevation, drainage line definition, watershed delineation, drainage feature characterization and geometric network generation. With sufficient resolution of DEM interpolated from point elevation data, all water bodies extracted from topographic maps in the basin were critically characterized‐‐‐the depth and water volume of lakes, ponds, and rivers were numerically computed. The final goal of this paper is to calculate surface runoff of the study basin based on a GIS‐based watershed management approach. The work was also processed under another extension called the ArcCN‐Runoff model, which ran on the background of ArcGIS software. This extension tool was built based on a very popular model for surface runoff estimation known as the Soil Conservation Service‐Curve Number (SCS‐CN) model. A total discharge volume in the northern sub‐watershed region of the basin was consequently computed on a monthly basis throughout one year. The computed discharges were totally consistent with those observed, and each of the discharges was also confirmed to be responsible for rainfall. These indicate that SCS‐CN and ArcCN‐Runoff models used in this paper are definitely valid and can be applied to other related projects of surface runoff calculation.

Improved accuracy in terminal restriction fragment length polymorphism phylogenetic analysis using a novel internal size standard definition

Terminal restriction fragment length polymorphism (T-RFLP) analysis is commonly used to analyze microbial communities, including oral microflora. However, accurate identification of terminal restriction fragment (T-RF) origins is prevented by unpredictable errors in sizing, thus necessitating the clone library analysis. To minimize sizing errors, we proposed optimizing the size definition of internal standards. GeneScan-1000 ROX was regenerated as an internal standard by redefining the fragment sizes in terms of molecular weight (MW) based on their mobility relative to 6-carboxyfluorescein (FAM) -labeled restriction fragments derived from the 16S recombinant RNA gene of Porphyromonas gingivalis. Using the new size definition, the average sizing error among eight oral bacteria from six phyla was estimated and compared with that of the conventional method. Microbial communities isolated from saliva were analyzed using the new MW size definition. Bacterial species were assigned to peaks using TRFMA, a Web-based tool for T-RFLP analysis, and compared with those identified in a clone library analysis. Using the new size definition, the average sizing error for 40 T-RFs was drastically reduced from 2.42 to 0.62 bases, and large sizing errors (more than two bases) were eliminated. More than 90% of the total bacterial clones detected by the clone library analysis were assigned by T-RFLP. The size definition of the newly constructed internal standards reduced fragment sizing errors and allowed for accurate assignment of bacteria to peaks by the T-RFLP analysis. This provided a more effective means for studying microbial communities, including the oral microflora.

Parasperm: morphological and functional studies on nonfertile sperm

Sperm polymorphism, a phenomenon in which more than one type of sperm is produced within a species, occurs widely in animals from invertebrates to vertebrates. Sperm in this phenomenon can be categorized into fertile sperm and nonfertile sperm on the basis of fertilization ability. Nonfertile sperm can be further classified into parasperm and aberrant deformed sperm. Parasperm are sperm produced through a constant developmental process along with normal fertile eusperm, and they are readily distinguished from deformed sperm, which are irregularly crippled by unpredictable errors at certain stages during spermatogenesis. Sperm identified as parasperm occur widely in invertebrates but are presently quite limited in vertebrates. This may be the result of the deficiency both of studies on parasperm and of clear criteria to identify parasperm in vertebrates. Some vertebrates show unique spermatogenesis, such as symplastic spermatid and semicystic spermatogenesis. Thus, parasperm must be identified by comparing cells in each cyst and in semen, because irregularly shaped cells in the seminal duct could be either parasperm or normal spermatids. Although parasperm are identified by clear criteria in vertebrates, only in cottoid fishes to date, it is possible for parasperm to be discovered in other vertebrates. Recently, roles related to sperm competition have been reported in several species (e.g., the marine cottoid fish Hemilepidotus gilberti), and, with some of them, parasperm production is influenced by an intraspecific factor such as a sex ratio or the density of a population. Sperm competition is one of the important candidates for influencing evolution of parasperm functions, but not all parasperm seem to have a relation to sperm competition. Parasperm function may relate to the ecological conditions of each species that produces parasperm. Studies on parasperm function will be advanced by an ecological approach concerning male fertilization success as well as cytological investigation for parasperm.

Predictive information and error processing: The role of medial‐frontal cortex during motor control

We have recently provided evidence that an error-related negativity (ERN), an ERP component generated within medial-frontal cortex, is elicited by errors made during the performance of a continuous tracking task (O.E. Krigolson & C.B. Holroyd, 2006). In the present study we conducted two experiments to investigate the ability of the medial-frontal error system to evaluate predictive error information. In two experiments participants used a joystick to perform a computer-based continuous tracking task in which some tracking errors were inevitable. In both experiments, half of these errors were preceded by a predictive cue. The results of both experiments indicated that an ERN-like waveform was elicited by tracking errors. Furthermore, in both experiments the predicted error waveforms had an earlier peak latency than the unpredicted error waveforms. These results demonstrate that the medial-frontal error system can evaluate predictive error information.

Comment on ‘Structure of the transverse profile of Gaussian-model non-paraxial electromagnetic beams’

Specification of Gaussian and the other boundary field distributions with continuous Fourier spectra results in unpredictable latent error. Fourier spectra of the field in any plane have singularities that can be neglected only in the paraxial approximation. For any conclusions that relate to non-paraxial beam propagation the analysis of approximation errors is necessary without question.

Predictors of occupational exposure to styrene and styrene-7,8-oxide in the reinforced plastics industry

Objective: To identify demographic and work related factors that predict blood levels of styrene and styrene-7,8-oxide (SO) in the fibreglass reinforced plastics (FRP) industry. Methods: Personal breathing-zone air samples and...