Precise Particle Tracking Against a Complicated Background: Polynomial Fitting with Gaussian Weight

We present a new particle tracking software algorithm designed to accurately track the motion of low-contrast particles against a background with large variations in light levels. The method is based on a polynomial fit of the intensity around each feature point, weighted by a Gaussian function of the distance from the centre, and is especially suitable for tracking endogeneous particles in the cell, imaged with bright field, phase contrast or fluorescence optical microscopy. Furthermore, the method can simultaneously track particles of all different sizes, and allows significant freedom in their shape. The algorithm is evaluated using the quantitative measures of accuracy and precision of previous authors, using simulated images at variable signal-to-noise ratios. To these we add a new test of the error due to a non-uniform background. Finally the tracking of particles in real cell images is demonstrated. The method is made freely available for non-commencial use as a software package with a graphical user-inferface, which can be run within the Matlab programming environment

Cardiac Masses on Cardiac CT: A Review

Cardiac masses are rare entities that can be broadly categorized as either neoplastic or non-neoplastic. Neoplastic masses include benign and malignant tumors. In the heart, metastatic tumors are more common than primary malignant tumors. Whether incidentally found or diagnosed as a result of patients’ symptoms, cardiac masses can be identified and further characterized by a range of cardiovascular imaging options. While echocardiography remains the first-line imaging modality, cardiac computed tomography (cardiac CT) has become an increasingly utilized modality for the assessment of cardiac masses, especially when other imaging modalities are non-diagnostic or contraindicated. With high isotropic spatial and temporal resolution, fast acquisition times, and multiplanar image reconstruction capabilities, cardiac CT offers an alternative to cardiovascular magnetic resonance imaging in many patients. Additionally, cardiac masses may be incidentally discovered during cardiac CT for other reasons, requiring imagers to understand the unique features of a diverse range of cardiac masses. Herein, we define the characteristic imaging features of commonly encountered and selected cardiac masses and define the role of cardiac CT among noninvasive imaging options

Confocal microscopy of colloidal particles: towards reliable, optimum coordinates

Over the last decade, the light microscope has become increasingly useful as a quantitative tool for studying colloidal systems. The ability to obtain particle coordinates in bulk samples from micrographs is particularly appealing. In this paper we review and extend methods for optimal image formation of colloidal samples, which is vital for particle coordinates of the highest accuracy, and for extracting the most reliable coordinates from these images. We discuss in depth the accuracy of the coordinates, which is sensitive to the details of the colloidal system and the imaging system. Moreover, this accuracy can vary between particles, particularly in dense systems. We introduce a previously unreported error estimate and use it to develop an iterative method for finding particle coordinates. This individual-particle accuracy assessment also allows comparison between particle locations obtained from different experiments. Though aimed primarily at confocal microscopy studies of colloidal systems, the methods outlined here should transfer readily to many other feature extraction problems, especially where features may overlap one another.Comment: Accepted by Advances in Colloid and Interface Scienc

Multi-particle three-dimensional coordinate estimation in real-time optical manipulation

oai:ojs.pkp.sfu.ca:article/304We have previously shown how stereoscopic images can be obtained in our three-dimensional optical micromanipulation system [J. S. Dam et al, Opt. Express 16, 7244 (2008)]. Here, we present an extension and application of this principle to automatically gather the three-dimensional coordinates for all trapped particles with high tracking range and high reliability without requiring user calibration. Through deconvolving of the red, green, and blue colour planes to correct for bleeding between colour planes, we show that we can extend the system to also utilize green illumination, in addition to the blue and red. Applying the green colour as on-axis illumination yields redundant information for enhanced error correction, which is used to verify the gathered data, resulting in reliable coordinates as well as producing visually attractive images

Inter-organizational Collaborations Working to Change Policies that Affect Adolescents: A Qualitative Study of Three Youth-Serving Inter-organizational Collaborations.

Differences in health status by race, ethnicity, and socioeconomic status have been well documented in the literature. Inter-organizational collaborations (IOCs) are a strategy used to address public health concerns and are useful in addressing differences in health status that are due to injustice. This study uses a social determinants of health framework, which describes how factors at the macro, community, interpersonal and individual levels contribute to inequities. Policy change is used to address these social determinants of health inequities. The purpose of this study is to identify factors that are challenges or facilitating factors to IOCs’ effectiveness and to describe how youth engage in policy advocacy initiatives. The study uses a case study design and data collection of interviews, a document review, and observations of events that were conducted in 2011. A grounded theory approach to data analysis was used. Interview transcripts were coded using in vivo coding techniques. Axial codes were developed based upon these codes and researcher memos. Documents and observation notes were then reviewed and memos were generated. This analysis led to the development of a theory that is grounded in the data. This theory describes the ways in which, within a social, economic, and political environment, IOCs apply resources (members, staff, youth, and financial resources) to conduct policy advocacy activities. These activities facilitate the development of relationships with various entities, including policy makers, media, funders, youth, and the community, to accomplish the intermediate objectives of increasing access to policy makers, resources, awareness of the issue, and the base of support. These intermediate objectives then lead to the IOC goals of a change in policy and social and institutional changes that addresses social determinants, leading to a reduction in health inequities. Implications for public health practitioners and researchers, policy makers, and entities that fund IOCs are discussed.PHDHealth Behavior And Health EducationUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/95933/1/rcheezum_1.pd

Importin-β modulates the permeability of the nuclear pore complex in a Ran-dependent manner

Soluble karyopherins of the importin-β (impβ) family use RanGTP to transport cargos directionally through the nuclear pore complex (NPC). Whether impβ or RanGTP regulate the permeability of the NPC itself has been unknown. Here, we identify a stable pool of impβ at the NPC. A subpopulation of this pool is rapidly turned-over by RanGTP, likely at Nup153. Impβ, but not transportin-1 (TRN1), alters the pore's permeability in a Ran-dependent manner, suggesting that impβ is a functional component of the NPC. Upon reduction of Nup153 levels, inert cargos more readily equilibrate across the NPC yet active transport is impaired. When purified impβ or TRN1 are mixed with Nup153 in vitro, higher-order, multivalent complexes form. RanGTP dissolves the impβ•Nup153 complexes but not those of TRN1•Nup153. We propose that impβ and Nup153 interact at the NPC's nuclear face to form a Ran-regulated mesh that modulates NPC permeability

Cardiac tamponade in association with anorexia nervosa: A case report and review of the literature

Anorexia nervosa (AN) is a complex psychiatric disorder that can have devastating cardiovascular complications. Its lesser-known association with pericardial effusion has been recently described in the literature. We present the case of a 45 year-old female who presented with a recurrent small bowel obstruction requiring lysis of adhesions and who was found to have a large pericardial effusion that progressed to cardiac tamponade necessitating surgical intervention. The patient had a body mass index of 14.8 kg/m2 (i.e. 71% of ideal body weight) and a long-standing history of food aversion, extreme exercise habits, and weight obsession consistent with AN. To the best of our knowledge, this is the first case of AN-associated cardiac tamponade in the United States, and the first requiring surgical intervention. In conclusion, with this and current data regarding AN-associated pericardial effusions, we recommend a low threshold for performing pre-operative echocardiography for those in whom AN is suspected

Multiple Particle Tracking and Two-Point Microrheology in Cells

Mechanical stress and stiffness are increasingly recognized to play important roles in numerous cell biological processes, notably cell differentiation and tissue morphogenesis. Little definite is known, however, about how stress propagates through different cell structures or how it is converted to biochemical signals via mechanotransduction, due in large part to the difficulty of interpreting many cell mechanics experiments. A newly developed technique, two-point microrheology (TPM), can provide highly interpretable, quantitative measurements of cells’ frequency-dependent shear moduli and spectra of their fluctuating intracellular stresses. TPM is a non-invasive method based on measuring the Brownian motion of large numbers of intracellular particles using multiple particle tracking. While requiring only hardware available in many cell biology laboratories–a phase microscope and digital video camera, as a statistical technique, it also requires the automated analysis of many thousands of micrographs. Here we describe in detail the algorithms and software tools used for such large-scale multiple particle tracking, as well as common sources of error and the microscopy methods needed to minimize them. Moreover, we describe the physical principles behind TPM and other passive microrheology methods, their limitations, and typical results for cultured epithelial cells

Ranolazine in Symptomatic Diabetic Patients Without Obstructive Coronary Artery Disease: Impact on Microvascular and Diastolic Function

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139109/1/jah32151.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139109/2/jah32151_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139109/3/jah32151-sup-0001-TablesS1-S3.pd

Top‐Hat and Asymmetric Gaussian‐Based Fitting Functions for Quantifying Directional Single‐Molecule Motion

Single‐molecule fluorescence permits super‐resolution imaging, but traditional algorithms for localizing these isolated fluorescent emitters assume stationary point light sources. Proposed here are two fitting functions that achieve similar nanometer‐scale localization precision as the traditional symmetric Gaussian function, while allowing, and explicitly accounting for, directed motion. The precision of these methods is investigated through Fisher information analysis, simulation and experiments, and the new fitting functions are then used to measure, for the first time, the instantaneous velocity and direction of motion of live bacteria cells. These new methods increase the information content of single‐molecule images of fast‐moving molecules without sacrificing localization precision, thus permitting slower imaging speeds, and our new fitting functions promise to improve tracking algorithms by calculating velocity and direction during each image acquisition. Single molecules on the move: Two fitting functions are introduced for measuring in‐frame motion of isolated fluorescent emitters. These methods determine the instantaneous directionality and velocity of motion without sacrificing the localization precision. Theory, simulation, and experiments are used to validate the methods, and the fitting algorithms are applied to the motion of live bacteria cells (see picture).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106757/1/712_ftp.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106757/2/cphc_201300774_sm_miscellaneous_information.pd