DISTRIBUTION OF LABELED LYMPH NODE CELLS IN MICE DURING THE LYMPHOCYTOSIS INDUCED BY BORDETELLA PERTUSSIS

The mechanism by which Bordetella pertussis organisms and their products induce lymphocytosis in mice was analyzed in terms of the localization of syngeneic Cr-51-labeled lymph node cells. Labeled lymphoid cells incubated in vitro with the supernatant of B. pertussis cultures and then injected intravenously into normal recipients, or labeled cells injected into pertussis-treated recipients were unable to "home" to lymphoid organs but persisted for long periods in the blood. In animals "equipped" with a population of Cr-51-labeled lymphoid cells, administration of B. pertussis organisms or culture supernatant effected a shift of radioactivity from lymph nodes and spleen into the peripheral blood, coincident with the lymphocytosis. In in vitro experiments it was found that the active principle could bind to both erythrocytes and lymphocytes and could spontaneously elute from these cells onto labeled lymphocytes which were then unable to home efficiently. The data suggest that Bordetella pertussis-induced lymphocytosis involves a reversible attachment of the pertussis factor onto the surfaces of lymphocytes which prevents their recirculation to lymphoid organs. Recirculating lymphocytes are presumably affected as they emerge from lymphoid organs to enter the blood

A Stable Mimetic Finite-Difference Method for Convection-Dominated Diffusion Equations

Convection-diffusion equations arise in a variety of applications such as particle transport, electromagnetics, and magnetohydrodynamics. Simulation of the convection-dominated regime for these problems, even with high-fidelity techniques, is particularly challenging due to the presence of sharp boundary layers and shocks causing jumps and discontinuities in the solution, and numerical issues such as loss of the maximum principle in the discretization. These complications cause instabilities, admitting large oscillations in the numerical solution when using traditional methods. Drawing connections to the simplex-averaged finite-element method (S. Wu and J. Xu, 2020), this paper develops a mimetic finite-difference (MFD) discretization using exponentially-averaged coefficients to overcome instability of the numerical solution as the diffusion coefficient approaches zero. The finite-element framework allows for transparent analysis of the MFD, such as proving well-posedness and deriving error estimates. Numerical tests are presented confirming the stability of the method and verifying the error estimates

Measuring biometric sample quality in terms of biometric feature information in iris images

This paper develops an approach to measure the information content in a biometric feature representation of iris images. In this context, the biometric feature information is calculated using the relative entropy between the intraclass and interclass feature distributions. The collected data is regularized using a Gaussian model of the feature covariances in order to practically measure the biometric information with limited data samples. An example of this method is shown for iris templates processed using Principal-Component Analysis- (PCA-) and Independent-Component Analysis- (ICA-) based feature decomposition schemes. From this, the biometric feature information is calculated to be approximately 278bits for PCA and 288bits for ICA iris features using Masek's iris recognition scheme. This value approximately matches previous estimates of iris information content. Copyrigh

Welcome to EIT 2014

On April 24–26 2014, the 15th International Conference on Biomedical Applications of Electrical Impedance Tomography (EIT 2014) takes place at the Glen House Resort in Gananoque, Canada. Exciting developments are taking place in EIT: developments in hardware, software, and reconstruction algor

Knowing what was done: uses of a spreadsheet log file

Spreadsheet use in educational environments has become widespread, likely because of the flexibility and ease of use of these tools. However, they have serious shortcomings if the teacher is to understand exactly what students or others have done. It is far too easy for students to replace a formula that gives an apparently unacceptable answer with a number that they believe to be correct. The same concern applies to recorded marks, as well as to business spreadsheets and to other reports that are used for decision-making. While intentionally misleading changes to spreadsheet files receive much attention, simple mistakes are probably more common. Some of these, such as the Trans-Alta Utilities (Globe and Mail, 2003) cut and paste error that cost the firm $24 million (US), have extreme consequences. Few are merely embarrassing. A log file or audit trail, enhanced by suitable filters, can allow both intentional and accidental changes that cause erroneous results to be caught. In order to meet these requirements, we have developed server based software tool (“TellTable”) which allows editing, version control, and auditing of spreadsheet files. Users connect to the server using a standard web browser, and are able to access and edit spreadsheet files in a Java applet in the browser window. TellTable has been used for a pilot study to maintain marks and course information for a multi-section courses with several instructions and teaching assistants. This paper describes the TellTable software and preliminary results of the pilot test