Multidimensional Scanning Research Articles

A generic multi-dimensional scan-control scheme for test-cost reduction

1943 This paper proposes a generic multi-dimensional scan shift control concept for mul- tiple scan chain design. Multiple scan chain test scheme provides very low scan power by skipping (selectively load/unload) many long scan chain switching activities. Based on the two-dimensional scan shift control, we can achieve low test power with simple and small overhead structure. We can further extend the scheme to a generic N dimension test scheme. The proposed scheme skips many unnecessary don't care (X) patterns to reduce the test data volume and test time. The experimental results of the proposed 2-D scheme achieve significant improvement in shift power reduction, test volume and test time re- duction. Compared with traditional single scan chain design, the large benchmark b17 of ITC'99 has over 50% reduction in test data volume and over 40% reduction in test time with little area overhead, around 1% routing overhead, and the power reduction is over 97%.

Challenges of profile likelihood evaluation in multi-dimensional SUSY scans

Statistical inference of the fundamental parameters of supersymmetric theories is a challenging and active endeavor. Several sophisticated algorithms have been employed to this end. While Markov-Chain Monte Carlo (MCMC) and nested sampling techniques are geared towards Bayesian inference, they have also been used to estimate frequentist conifidence intervals based on the profile likelihood ratio. We investigate the performance and appropriate configuration of MultiNest, a nested sampling based algorithm, when used for profile likelihood-based analyses both on toy models and on the parameter space of the Constrained MSSM. We find that while the standard configuration previously used in the literarture is appropriate for an accurate reconstruction of the Bayesian posterior, the profile likelihood is poorly approximated. We identify a more appropriate MultiNest configuration for profile likelihood analyses, which gives an excellent exploration of the profile likelihood (albeit at a larger computational cost), including the identification of the global maximum likelihood value. We conclude that with the appropriate configuration MultiNest is a suitable tool for profile likelihood studies, indicating previous claims to the contrary are not well founded.

MLIP: using multiple processors to compute the posterior probability of linkage

BackgroundLocalization of complex traits by genetic linkage analysis may involve exploration of a vast multidimensional parameter space. The posterior probability of linkage (PPL), a class of statistics for complex trait genetic mapping in humans, is designed to model the trait model complexity represented by the multidimensional parameter space in a mathematically rigorous fashion. However, the method requires the evaluation of integrals with no functional form, making it difficult to compute, and thus further test, develop and apply. This paper describes MLIP, a multiprocessor two-point genetic linkage analysis system that supports statistical calculations, such as the PPL, based on the full parameter space implicit in the linkage likelihood.ResultsThe fundamental question we address here is whether the use of additional processors effectively reduces total computation time for a PPL calculation. We use a variety of data – both simulated and real – to explore the question "how close can we get?" to linear speedup. Empirical results of our study show that MLIP does significantly speed up two-point log-likelihood ratio calculations over a grid space of model parameters.ConclusionObserved performance of the program is dependent on characteristics of the data including granularity of the parameter grid space being explored and pedigree size and structure. While work continues to further optimize performance, the current version of the program can already be used to efficiently compute the PPL. Thanks to MLIP, full multidimensional genome scans are now routinely being completed at our centers with runtimes on the order of days, not months or years.

Parallel photopolymerisation with complex light patterns generated by diffractive optical elements

Photopolymerisation by scanning a focused laser beam is a powerful method to build structures of arbitrary complexity with submicrometer resolution. We introduce parallel photopolymerisation to enhance the efficiency. Instead of multidimensional scanning of a single focus, the structure is generated simultaneously with diffractive patterns. We used fixed diffractive optical elements (DOEs), kinoforms, and Spatial Light Modulators (SLMs). The possibilities of photopolymerisation using SLM were investigated: the added flexibility using the programmable device is demonstrated. By using these DOEs, straight and helical cross shaped columns were produced with a single scan at a rate about an order of magnitude faster than by simple scanning. The produced helical structures could be rotated by optical tweezers.

School-Based Prevalence Assessment of the Need for Mental Health Services: Survey Development and Pilot Study

Objective: The School Site Needs Assessment instrument was designed to provide a multidimensional environmental scan of potential need for mental health services in classrooms and schools. Method: Items of the instrument covering various academic, social, and mental health domains were developed based on analysis of previous case management contact data and input from stakeholders. The teacher-response instrument was piloted with a convenience sample of 85 classrooms in seven schools. Results: 43% of students were observed by teachers to have at least one problem that could likely result in referral to a case manager. Frequently counted problems included “disruptive in class” (14% of students), “failing” risk (13% of students), and “hyperactive”-related behaviors (10% of students). Conclusions: The School Site Needs Assessment can assist school social workers in assessing the environmental mental health context of students and classrooms from the important perspective of teachers, leading to classroom and school site interventions.

Multidimensional genome scans identify the combinations of genetic loci linked to diabetes-related phenotypes in mice

Most quantitative trait loci (QTL) studies have focused on detecting the genetic effects of individual QTLs. This study thoroughly dissected the genetic components of type 2 diabetic mice, including a search for epistatic interactions and multi-locus additive effects that result in variation in diabetes-related phenotypes. F2 population was generated from BKS.Cg-Leprdb+/+m and DBA/2 intercross and separated into six subpopulations by sex and the db-dependent diabetes severity. Single-locus and pairwise genome scans first identified the QTLs in these F2 subpopulations, and next covariate-dependent scans confirmed their sex-, db- and sex-by-db-specific effects in the combined populations. Single-locus genome scans detected four QTLs (QBIS1, QBIS2, QBIS3 and QBIS4) that presented their genetic effects beyond sex, but most QTLs showed their effects specifically in limited conditions. This highly conditional feature of the QTLs was accentuated in the pairwise analysis. The pairwise genome scans uncovered a total of 27 significantly interacting or additively acting pairs of loci, showing a better fit to explain the total phenotypic variation of the traits. These significant pairs affected the traits under constantly varying combinations of loci in a time series or in both sexes. In addition, pairwise analysis indicated the appropriate genetic background in constructing congenic strains to obtain the maximum power in the replication of phenotypes. Our study showed high degree of complexity in the genetics of type 2 diabetes in mice, and it suggested that a comprehensive understanding of the multi-locus effects was essential to disentangle the complex genetics of diabetes and obesity in humans.

Fast retrieval of high-dimensional feature vectors in P2P networks using compact peer data summaries

The retrieval facilities of most peer-to-peer (P2P) systems are limited to queries based on a unique identifier or a small set of keywords. The techniques used for this purpose are hardly applicable for content based image retrieval (CBIR) in a P2P network. Furthermore, we will argue that the curse of dimensionality and the high communication overhead prevent the adaptation of multidimensional search trees or fast sequential scan techniques for P2P CBIR. In the present paper we will propose two compact data representations that can be distributed in a P2P network and used as the basis for a source selection. This allows for communicating with only a small fraction of all peers during query processing without deteriorating the result quality significantly. We will also present experimental results confirming our approach.

Breakthrough of 225Ac and its radionuclide daughters from an 225Ac/213Bi generator: development of new methods, quantitative characterization, and implications for clinical use

Bisumth-213, a short-lived alpha particle emitting radionuclide, is generated from the decay of 225Ac, which has a half-life of 10 days. The development of a clinical 225Ac/213Bi generator and the preparation of a 213Bi radiolabeled antibody for radioimmunotherapy of leukemia have been reported. The 225Ac decay scheme is complex; therefore a thorough understanding of the impact of both the parent 225Ac and its daughters on radiolabeling, purification, and quantification is necessary for optimal use of the generator system. This paper reports: (i) unique new methods to measure 221Fr, 213Bi, and 209Pb, the prominent daughters of 225Ac; and (ii) a quantitative evaluation of 225Ac/213Bi generator breakthrough and the radionuclidic purity of 213Bi labeled radiopharmaceutical dose formulations. A quantitative multi-dimensional proportional scanning method was employed to distinguish and measure specific daughter radionuclides. This method combines thin layer chromatography in two perpendicular directions with attenuated collimation as a function of time for data collection and analysis. Francium-221 and 213Bi eluted differentially from the generator, and 221Fr contributed minimally to unchelated 213Bi in the reaction and final products. Lead-209 was present in the reaction solution, but not strongly bound by the chelating moiety either (i) under the 213Bi labeling reaction conditions or (ii) following chelated 213Bi decay. As a consequence of incorporating several new procedures to the operation of the generator, 225Ac breakthrough in the final product was further reduced and represented a trivial contaminant in the final drug formulations.

The extended surface forces apparatus. Part I. Fast spectral correlation interferometry

This article describes details of the operation and performance of fast spectral correlation interferometry, which allows for considerably improved operation of the surface forces apparatus. Up to 150 interference fringes can be simultaneously tracked over a wide spectral range, leading to considerably more precise and simultaneous extraction of multiple optical quantities, over a greatly extended distance range. When used for surface-separation measurement, a precision of 25 pm is readily achievable over a distance ranging from 0 to >10 μm. Data acquisition rates are also considerably improved, allowing for dynamic measurements. Automated actuation of optical deflectors introduces a multidimensional scanning capability to the optical probe with a lateral resolution of 1 μm. The entire process is computer controlled and features unattended batch processing of complex measurements. This publication illustrates experimental setup, methodology, measurements, and detailed error calculation for a selection of practically relevant situations in the extended surface forces apparatus.

Estimating the Distributions of Scan Statistics with High Precision

In many statistical applications one is concerned with the estimation of the distribution of the maximum or minimum number of points in a moving window of fixed length, called scan statistics. Scan statistics are also extremes of 1-dependent sequences. A result of Haiman (1999) provides approximations of these distributions together with sharp bounds for the corresponding errors. Applications concern the maximum cluster of points on a line or on a circle and multiple coverage by subintervals or subarcs of fixed size. We compare our method with some existing empirical and non empirical methods and show how it can be applied to multidimensional scanning

Correction for the twist and the conical defects of a sagittaly bent crystal

Abstract The symmetrical bending of the focusing crystal of a double X-ray monochromator is a difficult problem. Indeed, the slope due to the curvature is usually three orders of magnitude higher than the accepted slope error (typically, the Darwin width of the crystal). In these conditions, even a low parasitic slope error induced by the bending process may lead to quite a strong intensity decrease. When the bending moment is applied, the main parasitic distortions which may appear are typically the anticlastic curvature, the inhomogeneous sagittal curvature, the conical shape and the twist. On the D2AM beamline at the ESRF, a program called CHKC2 has been developed to correct on-line the latter two distortions: the conical shape and the twist. On this beamline the X-ray beam, which has been collimated by a grazing angle mirror, is monochromatized first by a flat silicon crystal, and then diffracted by the sagittaly curved crystal. A fluorescent screen gives an image of this diffracted beam. The CHKC2 program records a series of images of the beam diffracted by the sagittaly curved crystal while rotating this crystal with respect to the flat one. An automatic analysis of this topography (plane-wave topography) is then performed in order to evaluate the behavior of the tuned areas and compare it to a model. An accurate correction is proposed to the beamline operator so that optimisation using long multidimensional scanning is no more necessary.

Linkage of protonation and anion binding to the folding of Sac7d

The temperature, pH, and salt dependence of the folding of recombinant Sac7d from the hyperthermophile Sulfolobus acidocaldarius is mapped using multi-dimensional differential scanning calorimetry (DSC) and folding progress surfaces followed by circular dichroism. Linkage relations are derived to explain the observed dependencies, and it is shown that the data can be explained by the linkage of at least two protonation reactions and two anion binding sites to a two-state unfolding process. Circular dichroism spectra indicate that a native-like fold is stabilized at acid pH by anion binding. An apparent binding isotherm surface (folding progress versus pH and salt) is used to obtain intrinsic chloride binding constants as a function of pH for both sites. A saddle is predicted in the folding progress surface (progress versus temperature and pH) at low salt with a minimum near pH 2 and 20°C with approximately 25% of the protein folded. The position of the saddle is sensitive to the intrinsic Δ C° p of unfolding and provides a third measure of Δ C° p independent of that obtained by a Kirchhoff plot of DSC data and chemical denaturation. The observed enthalpy of unfolding approaches zero near the saddle making the unfolding largely invisible to DSC under these conditions. The linkage analysis demonstrates that the Δ C° p for unfolding obtained from a Kirchhoff plot of DSC data should be distinguished from the intrinsic Δ C° p of unfolding. It is shown that the discrepancy between the free energy of unfolding for Sac7d obtained by DSC and that obtained by chemical denaturation may be explained by the linkage of protonation and anion binding to protein folding. The linkage analysis demonstrates the limitations of using the Δ H cal/Δ H vh ratio as an indication of two-state unfolding.