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Consider a network where two routes are available for users wishing to travel from a source to a destination. On one route (which could be viewed as private transport) service slows as traffic increases. On the other (which could be viewed as public transport) the service frequency increases with demand. The Downs-Thomson paradox occurs when improvements in service produce an overall decline in performance as user equilibria adjust. Using the model proposed by Calvert [10], with a ⋅|M|1 queue corresponding to the private transport route, and a bulk-service infinite server queue modelling the public transport route, we give a complete analysis of this system in the setting of probabilistic routing. We obtain the user equilibria (which are not always unique), and determine their stability.AMS subject classification: 60K30, 90B15, 90B20, 91A10, 91A13This revised version was published online in June 2005 with corrected coverdate 相似文献
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E. Lukevics L. Ignatovich I. Sleiksha V. Romanov S. Grinberga J. Popelis I. Shestakova 《Chemistry of Heterocyclic Compounds》2007,43(2):143-150
A new method was developed for the synthesis of silicon-and germanium-containing acetylfurans and acetylthiophene by metallation
of 2-acetylfuran or 2-acetylthiophene with n-BuLi at low temperature after protection of the carbonyl group with lithium N-methylpiperazide
and reaction of the lithium derivative with various trialkyl-, alkylphenyl-, and cycloalkylchlorosilanes or trialkylchloro(bromo)germanes.
The cytotoxic activity of the new compounds was studied, and it was established that the silicon-and germanium-containing
acetylfurans and acetylthiophenes are substances with low toxicity (LD50 312->2000 mg/kg) and have low cytotoxicity toward HT-1080 and MG-22A tumor cells.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 192–199, February, 2007. 相似文献
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JPC – Journal of Planar Chromatography – Modern TLC - Mesembrine-type alkaloids are reported to be responsible for the psychoactive properties of Sceletium tortuosum. The aim of the... 相似文献
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Nikita Brodyagin Aubrey L. Maryniak Ilze Kumpina John M. Talbott Dr. Martins Katkevics Prof. Dr. Eriks Rozners Prof. Dr. James A. MacKay 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(13):4332-4335
Peptide nucleic acids (PNA) with extended isoorotamide containing nucleobases ( I o ) were designed for binding A–U base pairs in double-stranded RNA. Isothermal titration calorimetry and UV thermal melting experiments revealed improved affinity for A–U using the Io scaffold in PNA. PNAs having four sequential Io extended nucleobases maintained high binding affinity. 相似文献
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Luba Ignatovich Olga Starkova Vitalijs Romanovs Ilze Sleiksha Irina Shestakova Jury Popelis Edmunds Lukevics 《Comptes Rendus Chimie》2013,16(6):621-627
The reaction of 1,2-phenylenediamine with a variety of silicon- or germanium-containing 2-furaldehydes or 2-thienylcarbaldehydes in DMFA gave the corresponding benzimidazole derivatives in moderate yields (36–49%) in the presence of sodium hydrogen sulfite. As a result, a new series of silyl, germyl substituted hetarylbenzimidazoles were synthesized and their in vitro cytotoxicity was studied. The quaternisation of N-substituted benzimidazoles by heating with various alkyl, allyl and propargyl chlorides and bromides leads to the formation of benzimidazolinium salts. Potential cytotoxic activity of synthesized new benzimidazoles and benzimidazolinium salts was tested in vitro on two monolayer tumour cell lines: MG-22A (mouse hepatoma), HT-1080 (human fibrosarcoma) and normal mouse fibroblasts (NIH 3T3) and compared with corresponding benzimidazoles. 相似文献
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Synthesis and Cytotoxic Activity of 1‐{3‐[1‐(5‐Organylsilylfuran‐2‐yl)silinan‐1‐yl]propyl}amines and Some Trimethylgermyl Analogues
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Dr. Luba Ignatovich Dr. Vitalijs Romanovs Velta Muravenko Ilze Sleiksha Dr. Jury Popelis Dr. Irina Shestakova 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):12786-12788
New highly cytotoxic 1‐{3‐[1‐(5‐organylsilyl‐furan‐2‐yl)silinan‐1‐yl]propyl}amines and some trimethylgermyl analogues (IC50 1–7 μg mL?1) have been synthesized by a hydrosilylation reaction of aliphatic and heterocyclic N‐allylamines in the presence of Speier’s catalyst. The effects of the silacycle, the element‐organic substituent in position 5 of the furan ring, and the structure of the amine on the cytotoxicity of the new compounds have been studied. 相似文献
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Consider a system of two queues in parallel, one of which is a ⋅|M|1 single-server infinite capacity queue, and the other a ⋅|G
(N)|∞ batch service queue. A stream of general arrivals choose which queue to join, after observing the current state of the
system, and so as to minimize their own expected delay. We show that a unique user equilibrium (user optimal policy) exists
and that it possesses various monotonicity properties, using sample path and coupling arguments. This is a very simplified
model of a transportation network with a choice of private and public modes of transport. Under probabilistic routing (which
is equivalent to the assumption that users have knowledge only of the mean delays on routes), the network may exhibit the
Downs–Thomson paradox observed in transportation networks with expected delay increasing as the capacity of the ⋅|M|1 queue (private transport) is increased. We give examples where state-dependent routing mitigates the Downs–Thomson effect
observed under probabilistic routing, and providing additional information on the state of the system to users reduces delay
considerably. 相似文献
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Paweł Górnaś Inga Mišina Ilze Grāvīte Arianne Soliven Edīte Kaufmane Dalija Segliņa 《Natural product research》2015,29(13):1222-1227
Composition of tocochromanols in kernels recovered from 16 different apricot varieties (Prunus armeniaca L.) was studied. Three tocopherol (T) homologues, namely α, γ and δ, were quantified in all tested samples by an RP-HPLC/FLD method. The γ-T was the main tocopherol homologue identified in apricot kernels and constituted approximately 93% of total detected tocopherols. The RP-UPLC-ESI/MSn method detected trace amounts of two tocotrienol homologues α and γ in the apricot kernels. The concentration of individual tocopherol homologues in kernels of different apricots varieties, expressed in mg/100 g dwb, was in the following range: 1.38–4.41 (α-T), 42.48–73.27 (γ-T) and 0.77–2.09 (δ-T). Moreover, the ratio between individual tocopherol homologues α:γ:δ was nearly constant in all varieties and amounted to approximately 2:39:1. 相似文献
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