Evaluating Likelihood Ratio (LR) for firearm evidence identifications in forensic science based on the Congruent Matching Cells (CMC) method.

Firearm evidence identification has been challenged by the 2008 and 2009 National Research Council (NRC) reports and by legal proceedings on its fundamental assumptions, its procedure involving subjective interpretations, and the lack of a statistical foundation for evaluation of error rates or other measures for the weight of evidence. To address these challenges, researchers of the National Institute of Standards and Technology (NIST) recently developed a Congruent Matching Cells (CMC) method for automatic and objective firearm evidence identification and quantitative error rate evaluation. Based on the CMC method, a likelihood ratio (LR) procedure is proposed in this paper aiming to provide a scientific basis for firearm evidence identification and a method for evaluation of the weight of evidence.

Estimating error rates for firearm evidence identifications in forensic science.

Estimating error rates for firearm evidence identification is a fundamental challenge in forensic science. This paper describes the recently developed congruent matching cells (CMC) method for image comparisons, its application to firearm evidence identification, and its usage and initial tests for error rate estimation. The CMC method divides compared topography images into correlation cells.

Evaluation of carbon nanotube probes in critical dimension atomic force microscopes.

The decreasing size of semiconductor features and the increasing structural complexity of advanced devices have placed continuously greater demands on manufacturing metrology, arising both from the measurement challenges of smaller feature sizes and the growing requirement to characterize structures in more than just a single critical dimension. For scanning electron microscopy, this has resulted in increasing sophistication of imaging models. For critical dimension atomic force microscopes (CD-AFMs), this has resulted in the need for smaller and more complex tips.

Topography measurements and applications in ballistics and tool mark identifications.

The application of surface topography measurement methods to the field of firearm and toolmark analysis is fairly new. The field has been boosted by the development of a number of competing optical methods, which has improved the speed and accuracy of surface topography acquisitions. We describe here some of these measurement methods as well as several analytical methods for assessing similarities and differences among pairs of surfaces.

Role of the Na(+)-translocating NADH:quinone oxidoreductase in voltage generation and Na(+) extrusion in Vibrio cholerae.

For Vibrio cholerae, the coordinated import and export of Na(+) is crucial for adaptation to habitats with different osmolarities. We investigated the Na(+)-extruding branch of the sodium cycle in this human pathogen by in vivo (23)Na-NMR spectroscopy. The Na(+) extrusion activity of cells was monitored after adding glucose which stimulated respiration via the Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR).

The structure of Na⁺-translocating of NADH:ubiquinone oxidoreductase of Vibrio cholerae: implications on coupling between electron transfer and Na⁺ transport.

The Na⁺-translocating NADH:ubiquinone oxidoreductase (Na⁺-NQR) of Vibrio cholerae is a respiratory complex that couples the exergonic oxidation of NADH to the transport of Na⁺ across the cytoplasmic membrane. It is composed of six different subunits, NqrA, NqrB, NqrC, NqrD, NqrE, and NqrF, which harbor FAD, FMN, riboflavin, quinone, and two FeS centers as redox co-factors. We recently determined the X-ray structure of the entire Na⁺-NQR complex at 3.

Serine 26 in the PomB subunit of the flagellar motor is essential for hypermotility of Vibrio cholerae.

Vibrio cholerae is motile by means of its single polar flagellum which is driven by the sodium-motive force. In the motor driving rotation of the flagellar filament, a stator complex consisting of subunits PomA and PomB converts the electrochemical sodium ion gradient into torque. Charged or polar residues within the membrane part of PomB could act as ligands for Na+, or stabilize a hydrogen bond network by interacting with water within the putative channel between PomA and PomB.

Structure of the V. cholerae Na+-pumping NADH:quinone oxidoreductase.

NADH oxidation in the respiratory chain is coupled to ion translocation across the membrane to build up an electrochemical gradient. The sodium-translocating NADH:quinone oxidoreductase (Na(+)-NQR), a membrane protein complex widespread among pathogenic bacteria, consists of six subunits, NqrA, B, C, D, E and F. To our knowledge, no structural information on the Na(+)-NQR complex has been available until now.

Central role of the Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR) in sodium bioenergetics of Vibrio cholerae.

Vibrio cholerae is a Gram-negative bacterium that lives in brackish or sea water environments. Strains of V. cholerae carrying the pathogenicity islands infect the human gut and cause the fatal disease cholera.

Crystallization and preliminary analysis of the NqrA and NqrC subunits of the Na+-translocating NADH:ubiquinone oxidoreductase from Vibrio cholerae.

The Na+-translocating NADH:ubiquinone oxidoreductase (Na+-NQR) from Vibrio cholerae is a membrane protein complex consisting of six different subunits NqrA-NqrF. The major domains of the NqrA and NqrC subunits were heterologously expressed in Escherichia coli and crystallized. The structure of NqrA1-377 was solved in space groups C222₁ and P2₁ by SAD phasing and molecular replacement at 1.

The Second National Ballistics Imaging Comparison (NBIC-2).

In response to the guidelines issued by the American Society of Crime Laboratory Directors/Laboratory Accreditation Board (ASCLD/LAB-International) to establish traceability and quality assurance in U.S. crime laboratories, NIST and the ATF initiated a joint project, entitled the National Ballistics Imaging Comparison (NBIC).

The function of the Na+-driven flagellum of Vibrio cholerae is determined by osmolality and pH.

Vibrio cholerae is motile by its polar flagellum, which is driven by a Na(+)-conducting motor. The stators of the motor, composed of four PomA and two PomB subunits, provide access for Na(+) to the torque-generating unit of the motor. To characterize the Na(+) pathway formed by the PomAB complex, we studied the influence of chloride salts (chaotropic, Na(+), and K(+)) and pH on the motility of V.

Automatic identification of bullet signatures based on consecutive matching striae (CMS) criteria.

The consecutive matching striae (CMS) numeric criteria for firearm and toolmark identifications have been widely accepted by forensic examiners, although there have been questions concerning its observer subjectivity and limited statistical support. In this paper, based on signal processing and extraction, a model for the automatic and objective counting of CMS is proposed. The position and shape information of the striae on the bullet land is represented by a feature profile, which is used for determining the CMS number automatically.

The novel NhaE-type Na(+)/H (+) antiporter of the pathogenic bacterium Neisseria meningitidis.

Neisseria meningitidis is a pathogenic bacterium responsible for meningitis. The mechanisms underlying the control of Na(+) transmembrane movement, presumably important to pathogenicity, have been barely addressed. To elucidate the function of the components of the Na(+) transport system in N.

The National Ballistics Imaging Comparison (NBIC) project.

In response to the guidelines issued by the American Society of Crime Laboratory Directors/Laboratory Accreditation Board (ASCLD/LAB-International) to establish traceability and quality assurance in U.S. crime laboratories, a NIST/ATF joint project entitled National Ballistics Imaging Comparison (NBIC) was initialized in 2008.

Selecting Valid Correlation Areas for Automated Bullet Identification System Based on Striation Detection.

Some automated bullet identification systems calculate a correlation score between two land impressions to measure their similarity. When extracting a compressed profile from the land impression of a fired bullet, inclusion of areas that do not contain valid individual striation information may lead to sub-optimal extraction and therefore may deteriorate the correlation result. In this paper, an edge detection algorithm and selection process are used together to locate the edge points of all tool-mark features and filter out those not corresponding to striation marks.

Striation density for predicting the identifiability of fired bullets with automated inspection systems.

Automated firearms identification systems will correlate a reference bullet with all evidence bullets without a selection procedure to exclude the bullets having insufficient bullet identifying signature. Correlations that include such bullets increase the workload and may affect the correlation accuracy. In this article, a parameter called striation density is proposed for determining and predicting bullet identifiability.

Pilot study of automated bullet signature identification based on topography measurements and correlations.

A procedure for automated bullet signature identification is described based on topography measurements using confocal microscopy and correlation calculation. Automated search and retrieval systems are widely used for comparison of firearms evidence. In this study, 48 bullets fired from six different barrel manufacturers are classified into different groups based on the width class characteristic for each land engraved area of the bullets.

An Iterative Image Registration Algorithm by Optimizing Similarity Measurement.

A new registration algorithm based on Newton-Raphson iteration is proposed to align images with rigid body transformation. A set of transformation parameters consisting of translation in x and y and rotation angle around z is calculated by optimizing a specified similarity metric using the Newton-Raphson method. This algorithm has been tested by registering and correlating pairs of topography measurements of nominally identical NIST Standard Reference Material (SRM 2461) standard cartridge cases, and very good registration accuracy has been obtained.

A moving window correlation method to reduce the distortion of scanning probe microscope images.

Many scanning probe microscopes such as the scanning tunneling microscope and atomic force microscope use piezoelectric actuators operating in open loop for generating the scans of the surfaces. However, nonlinearities mainly caused by hysteresis and drift of piezoelectric actuators reduce the positioning accuracy and produce distorted images. A moving window correlation method is proposed in this paper to determine and quantify the hysteresis.

Functional role of a conserved aspartic acid residue in the motor of the Na(+)-driven flagellum from Vibrio cholerae.

The flagellar motor consists of a rotor and a stator and couples the flux of cations (H(+) or Na(+)) to the generation of the torque necessary to drive flagellum rotation. The inner membrane proteins PomA and PomB are stator components of the Na(+)-driven flagellar motor from Vibrio cholerae. Affinity-tagged variants of PomA and PomB were co-expressed in trans in the non-motile V.

Evaluation of polydimethylsiloxane modification methods for cell response.

Many methods exist in the literature to modify surfaces with extracellular matrix (ECM) proteins prior to cell seeding. However, there are few studies that systematically characterize and compare surface properties and cell response results among modification methods that use different bonding mechanisms. In this work, we compare cell response and physical characterization results from fibronectin or laminin attached to polydimethylsiloxane (PDMS) elastomer surfaces by physical adsorption, chemisorption, and covalent attachment to determine the best method to modify a deformable surface.

Characterization of Probe Dynamic Behaviors in Critical Dimension Atomic Force Microscopy.

This paper describes a detailed computational model of the interaction between an atomic force microscope probe tip and a sample surface. The model provides analyses of dynamic behaviors of the tip to estimate the probe deflections due to surface intermittent contact and the resulting dimensional biases and uncertainties. Probe tip and cantilever beam responses to intermittent contact between the probe tip and sample surface are computed using the finite element method.

Arginine-induced conformational change in the c-ring/a-subunit interface of ATP synthase.

The rotational mechanism of ATP synthases requires a unique interface between the stator a subunit and the rotating c-ring to accommodate stability and smooth rotation simultaneously. The recently published c-ring crystal structure of the ATP synthase of Ilyobacter tartaricus represents the conformation in the absence of subunit a. However, in order to understand the dynamic structural processes during ion translocation, studies in the presence of subunit a are required.

Measurements and predictions of light scattering by clear coatings.

Comparisons are made between calculated and measured angle-resolved light-scattering distributions from clear dielectric isotropic epoxy coatings over a range of rms roughness conditions, resulting in strongly specular scattering to diffuse scattering characteristics. Calculated distributions are derived from topography measurements performed with interferometric microscopes. Two methods of calculation are used.