Controlling an oscillating Jackson-type network having state-dependent service rates

We consider a Jackson-type network comprised of two queues having state-dependent service rates, in which the queue lengths evolve periodically, exhibiting noisy cycles. To reduce this noise a certain heuristic, utilizing regions in the phase space in which the system behaves almost deterministically, is applied. Using this heuristic, we show that in order to decrease the probability of a customers overflow in one of the queues in the network, the server in that same queue – contrary to intuition – should be shut down for a short period of time. Further noise reduction is obtained if the server in the second queue is briefly shut down as well, when certain conditions hold.     

Preparation of isatoates from isatoic anhydride

A wide variety of alkyl isatoates can be prepared in good yield from the high temperature reaction of isatoic anhydride with alcohols. Isatoates were found to undergo an apparent high temperature rearrangement reaction. Proposed reaction schemes are presented for the formation of isatoates and the subsequent rearrangement reaction.     

Interfacial reciprocal grafting by free radical reactions in polymer blends

Recent developments in the field of reactive compatibilization of polymer blends prepared by melt processing focus on the addition of low molecular weight compounds. This work deals with in situ compatibilization through the formation of graft or crosslinked copolymers at the interface. Mixtures of semicrystalline hydrocarbon polymers have been subjected to free radical reactivity, in a co-rotating twin screw extruder (ZSK 30) in a single step. The particular system, high density polyethylene and polyamide 6, was blended in the presence of a peroxide and a reactive bifunctional monomer, maleic anhydride. Because of a combined effect, the reaction appears to occur mainly at the interface, where the resulting grafted copolymer acts as an anchor for the final stabilization of the biphasic system. Different analytical techniques, such as differential scanning calorimetry, scanning electron microscopy and tensile testing, helped in characterizing the resulting blends and confirmed the high level of interfacial grafting and the expected improvement in mechanical properties.     

Free Glycine Accelerates the Autoproteolytic Activation of Human Asparaginase

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Highlights? Increased expression of hASNase3 was observed in several tumors, but the relevance is unclear ? Cancer cells have increased glycolytic flux and thus have more glycine but less aspartate ? Glycine activates the asparaginase activity of hASNase3 by promoting self-cleavage ? Thus, glycine may act as a sensor that regulates cellular aspartate concentrations     

Theoretical and Experimental Analysis of Protoporphyrin IX Photodegradation Using Multi-Wavelength Light Sources

Photodynamic procedures have been used in many applications, ranging from cancer treatment to microorganism inactivation. Photodynamic reactions start with the activation of a photosensitizing molecule with light, leading to the production of cytotoxic molecules that promote cell death. However, establishing the correct light and photosensitizer dosimetry for a broadband light source remains challenging. In this study, we proposed a theoretical mathematical model for the photodegradation of protoporphyrin IX (PpIX), when irradiated by multi-wavelength light sources. The theoretical model predicts the experimental photobleaching (temporal change in PpIX concentration) of PpIX for different light sources. We showed that photobleaching occurs independently of the light source wavelengths but instead depends only on the number of absorbed photons. The model presented here can be used as an important mathematical approach to better understand current photodynamic therapy protocols and help achieve optimization of the doses delivered.     

Cis,anti, cis-Tricyclo[5.3.0.02,6]deca-4,9-dione

The chemical behavior and some physical properties (dipole moment, IR. vs. Raman spectra) of the titled compound are not fully consistent with a strictly centrosymmetric structure which might be expected for the anti configuration. The carbonyl groups are less reactive toward nucleophilic reagents and sp² → sp³ transformations as compared to cyclopentanone systems.     

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The Classical Constraint on Relevance

We show that as long as the propositional constants t and f are not included in the language, any language-preserving extension of any important fragment of the relevance logics R and RMI can have only classical tautologies as theorems (this includes intuitionistic logic and its extensions). This property is not preserved, though, if either t or f is added to the language, or if the contraction axiom is deleted.