A global study of Kondepudi’s pitchfork

This model reaction, studied so effectively by Kondepudi and his co-workers, is transferred here to a stirred tank. It is shown that, though the rate constants for the two pathways are identical, the stable steady state can still be one in which one or the other pathway is favoured enormously. We are indebted for partial support to the National Science Foundation through heir grant CPE 8112292.     

Online pairing of VoIP conversations

This paper answers the following question; given a multiplicity of evolving 1-way conversations, can a machine or an algorithm discern the conversational pairs in an online fashion, without understanding the content of the communications? Our analysis indicates that this is possible, and can be achieved just by exploiting the temporal dynamics inherent in a conversation. We also show that our findings are applicable for anonymous and encrypted conversations over VoIP networks. We achieve this by exploiting the aperiodic inter-departure time of VoIP packets, hence trivializing each VoIP stream into a binary time-series, indicating the voice activity of each stream. We propose effective techniques that progressively pair conversing parties with high accuracy and in a limited amount of time. Our findings are verified empirically on a dataset consisting of 1,000 conversations. We obtain very high pairing accuracy that reaches 97% after 5 min of voice conversations. Using a modeling approach we also demonstrate analytically that our result can be extended over an unlimited number of conversations.     

Assessing T-Cell Immunity in Kidney Transplant Recipients with Absent Antibody Production after a 3rd Dose of the mRNA-1273 Vaccine

The vulnerable population of kidney transplant recipients (KTRs) are low responders to COVID-19 vaccines, so specific immune surveillance is needed. The interferon-gamma (IFN-γ) release assay (IGRA) is effective in assessing T cell-mediated immunity. We assessed SARS-CoV-2-directed T cell responses in KTRs with absent antibody production after a third dose of the mRNA-1273 vaccine, using two different IGRAs. A cohort of 57 KTRs, who were actively followed up, received a third dose of the mRNA-1273 vaccine. After the evaluation of humoral immunity to SARS-CoV-2, 14 seronegative patients were tested with two commercial IGRAs (SD Biosensor and Euroimmun). Out of 14 patients, one and three samples were positive by IGRAs with Euroimmun and SD Biosensor, respectively. The overall agreement between the two assays was 85.7% (κ = 0.444). In addition, multivariate linear regression analysis showed no statistically significant association between the IFN-γ concentration, and the independent variables analyzed (age, gender, years since transplant, total lymphocytes cells/mcl, CD3+ cells/mcl, CD3+ CD4+ cells/mcl, CD3+ CD8+ cells/mcl, CD19+ cells/mcl, CD3-CD16+CD56+ cells/mcl) (p > 0.01). In a vulnerable setting, assessing cellular immune response to complement the humoral response may be advantageous. Since the two commercial IGRAs showed a good agreement on negative samples, the three discordant samples highlight the need for further investigations.     

Extraction and fractionation of wheat flour proteins

Extraction of wheat flour with 1.5% sodium dodecyl sulphate (SDS) solution dissolved 65–67% of the total flour nitrogen. The SDS-insoluble proteinaceous material was separated into glycoproteins-I, II and III by ultracentrifugation. Part of the SDS-soluble proteinaceous material was precipitated by addition of ethanol and separated into glycoproteins-IV, glutenins and globulins. The rest of the dissolved proteinaceous material was separated into glycoproteins-V, gliadins, glycoproteins-VI, and albumins by (NH₄)₂SO₄-precipitation and gel filtration chromatography.     

More on the dynamics of a stirred tank with consecutive reactions

The literature on the stirred tank reactor with consecutive reactions is reviewed and a census of multiplicity diagrams, bifurcation diagrams and phase portraits is given. The location of the organizing centre, introduced by Balakotaiah and Luss, and some features of the butterfly singularity are discu particularly with reference to variations in the ratio of activation energies. The forms that the regions of attraction of the various steady states ma take in the three-dimensional state space are also discussed.     

Effectiveness of catalytic archipelagos—II: Random arrays of random islands

Voronoi polygons are used to simulate a random distribution of irregularly shaped catalytic islands. Finite element mathematics is used to determine the catalytic effectiveness of the islands when adsorbed reactants diffuse and disappear by a first order reaction at their boundaries. It is found that the catalytic effectiveness of the islands at any fractional coverage can be estimated reasonably accurately either from asymptotic formulae, valid for certain values of diffusion, adsorption, and reaction constants, or from the equivalent annulus approximation found earlier to be accurate for certain regular arrays of regular islands. The equivalent annulus approximation allows analytic prediction of the catalytic effectiveness for any set of parameter conditions given only the fraction area ratio Γ/Ω. Both of these quantities of which can be determined directly from a photomicrog of a representative sample.     

ON THE CONCEPT OF THE STEADY STATE IN CHEMICAL REACTOR ANALYSIS

The inlet and outlet streams of a chemical reactor may reach a steady state before the internal distributions of concentration, etc. have come to the steady state. Such a steady state, in which the reactor is viewed only as a system with certain inputs and outputs, may be called the black-box steady state (BBSS). The existence of a BBSS does not always imply that of a true SS, and the BBSS may be attained in a finite time even though the SS is only attained asymptotically. Indeed under some circumstances the BBSS can be achieved immediately upon start-up. Provided that the internal transients are not catastrophic, the practical, or operator's, concept of a steady state is really that of a BBSS.