Nonstationary analysis of the loss queue and of queueing networks of loss queues

We present an iterative scheme based on the fixed-point approximation method, for the numerical calculation of the time-dependent mean number of customers and blocking probability functions in a nonstationary queueing network with multi-rate loss queues. We first show how the proposed method can be used to analyze a single-class, multi-class, and multi-rate nonstationary loss queue. Subsequently, the proposed method is extended to the analysis of a nonstationary queueing network of multi-rate loss queues. Comparisons with exact and simulation results showed that the results are consistently close to the exact results and they are always within simulation confidence intervals.     

CFD modeling for flow and mass transfer in spacer-obstructed membrane feed channels

The effect of spacer geometry on fluid dynamics and mass transfer in feed channels of spiral wound membranes has been investigated. Three-dimensional computational fluid dynamics (CFD) simulations reveal significant influence of spacer geometric parameters such as filament spacing, thickness and flow attack angle on wall shear rates and mass transfer coefficients. The spacers with filaments in axial and transverse direction induce higher shear stresses at the top membrane surface when compared to the bottom; the mass transfer rates are almost equal. The distribution of mass transfer coefficients become uniform when the spacing between axial filaments is increased or transverse filament thickness is decreased. For spacers with filaments inclined to the channel axis, the flow structure depends on spacing and flow attack angle. The fluid follows a zigzag path when spacing is greater while it begins to line-up with the filaments when spacing is reduced or flow attack angle is increased. The flow when aligned with the filaments increases the wall shear stress but confines the region of higher mass transfer coefficient values to a narrower portion. The zigzag flow movement increases these values on a major portion of membrane surface which enhances the mass transfer rates.     

Zero sets and uniqueness sets with one cluster point for the Dirichlet space

Zero sets and uniqueness sets of the Dirichlet space are not completely characterized yet. There are sufficient conditions for zero sets and necessary conditions for uniqueness sets and there is a gap in between. Our goal is to take some preliminary steps to fill this gap.     

Solitons in nonlinear directional couplers with optical metamaterials

This paper obtains bright, dark, and singular optical solitons in nonlinear directional couplers with optical metamaterials. The mathematical principle of undetermined coefficients is applied to extract these soliton solutions, with phase-matching condition. The constraint conditions for the existence of soliton solutions naturally emerge from the solutions. Both twin-core couplers and multiple-core couplers are studied in this paper.

     

Nonlinear semigroup approach to transport equations with delayed neutrons

This paper deal with a nonlinear transport equation with delayed neutron and general boundary conditions. We establish, via the nonlinear semigroups approach, the existence and uniqueness of the mild solution, weak solution, strong solution and local solution on L~p-spaces(1 ≤ p +∞). Local and non local evolution problems are discussed.     

Respiratory Motion Correction of Compressively Sampled Myocardial Perfusion Data by Using Robust Matrix Decomposition

Motion correction is a challenging problem in free breathing undersampled cardiac perfusion magnetic resonance images. It is due to aliasing artifacts in the reconstructed images and the rapid contrast changes in the perfusion images. In addition to the reconstruction limitations, many registration algorithms underperforms in the presence of the rapid intensity changes. In this paper, we propose a novel motion correction technique that reconstructs the motion-free images from the undersampled cardiac perfusion MR data. The technique utilizes the robust principal component analysis along with the periodic decomposition to separate the respiratory motion component that can be registered, from the unchanged contrast intensity variations. It was tested on synthetic data, simulated data, and the clinically acquired data. The performance of the method was qualitatively assessed and validated by comparing manually acquired time–intensity curves of the myocardial sectors to automatically generated curves before and after registration.     

A Bivalent Inhibitor of Prostate Specific Membrane Antigen Radiolabeled with Copper‐64 with High Tumor Uptake and Retention

Molecules containing lysine‐ureido‐glutamate functional groups bind to the active site of prostate specific membrane antigen, which is overexpressed in prostate cancer. To prepare copper radiopharmaceuticals for the diagnosis and therapy of prostate cancer, macrobicyclic sarcophagine ligands tethered to either one or two lysine‐ureido‐glutamate functional groups through an appropriate linker have been prepared. Sarcophagine ligands can be readily radiolabeled with positron‐emitting copper‐64 at room temperature. The bivalent agent, in which two targeting groups are tethered to a single copper complex, dramatically outperforms the monomeric agent with respect to tumor uptake and retention. The high tumor uptake, low background, and prolonged tumor retention, even at 24 hours post injection, suggest the bivalent agent is a promising diagnostic for prostate cancer and could be used for prospective dosimetry for therapy with a copper‐67 variant.     

Designing of new cationic surfactant based micellar systems as drug carriers: an investigation into the drug cell membrane interactions

This study highlights the utility of new pyridinium based cationic surfactants, N-(n-heptyl)-3-methylpyridinium bromide (Py7) and N-(n-nonyl)-3-methylpyridinium bromide (Py9), formed via a single step substitution reaction, for their application towards drugs delivery. Fourier-transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopic methods have been employed for the characterization of these amphiphiles. Aggregation behavior of the surfactants in solution i.e. the critical micelle concentration (CMC), has been investigated by conductometric and spectrophotometric analyses. The results reveal that the amphiphiles can act as excellent surface active agents due to their low critical micelle concentration (CMC). Furthermore, the interaction of these surfactants with two anionic drugs i.e., Ketoprofen (KP, 2-(3-Benzoylphenyl)propanoic acid) and Diclofenac sodium (DF, Sodium 2-(2,6-dichloranilino) phenylacetate), has been explored below and above the CMC value using UV-visible spectroscopy. The enhanced absorption intensities of both the drugs in the presence of synthesized surfactants indicated stronger interactions between surfactants and drugs molecules.