A discrete-time Markov modulated queuing system with batched arrivals

This paper examines a discrete-time queuing system with applications to telecommunications traffic. The arrival process is a particular Markov modulated process which belongs to the class of discrete batched Markovian arrival processes. The server process is a single server deterministic queue. A closed form exact solution is given for the expected queue length and delay. A simple system of equations is given for the probability of the queue exceeding a given length.Comment: to appear Performance Evaluatio

Biochemical effects of urapidil on red cell membrane ion transport systems in a population of elderly essential hypertensives.

The aim of our work was to verify the effect of urapidil on membrane ion transport systems. This was a randomized, double-blind, cross-over study which evaluated the clinical and biochemical effects of urapidil (30 mg twice daily in comparison with placebo) in a group of 10 elderly hypertensive patients (3 male, 7 female ranging from 68 to 90 years, mean age 79.2 +/- 7.6 years). For the evaluation in fresh erythrocytes of principal ion transport systems (cotransport Na+/K+, countertransport Na+/Li+, Na+/K+ ATPase pump. intracellular Na+ and K+) we used the nystatin technique. We found that urapidil activated the red cell membrane ions cotransport system (basal values: 83.7 +/- 50.3 mumol Na+ RBC 1-1.h-1, after 1 month of urapidil therapy: 181.5 +/- 89.3 mumol Na+ RBC 1-1.h-1) (P less than 0.01), without significant changes in the other biochemical parameters evaluated. Our data suggest that one of the mechanisms of the urapidil antihypertensive effect could involve an increase in the membrane sodium cotransport system

Antiplasmodial triterpenoids from the fruits of neem, Azadirachta indica.

J Nat Prod. 2010 Aug 27;73(8):1448-52. Antiplasmodial triterpenoids from the fruits of neem, Azadirachta indica. Chianese G, Yerbanga SR, Lucantoni L, Habluetzel A, Basilico N, Taramelli D, Fattorusso E, Taglialatela-Scafati O. Abstract Eight known and two new triterpenoid derivatives, neemfruitins A (9) and B (10), have been isolated from the fruits of neem, Azadirachta indica, a traditional antimalarial plant used by Asian and African populations. In vitro antiplasmodial tests evidenced a significant activity of the known gedunin and azadirone and the new neemfruitin A and provided useful information about the structure-antimalarial activity relationships in the limonoid class

Impact of repeated NeemAzal®-treated blood meals on the fitness of Anopheles stephensi mosquitoes

Background: Herbal remedies are widely used in many malaria endemic countries to treat patients, in particular in the absence of anti-malarial drugs and in some settings to prevent the disease. Herbal medicines may be specifically designed for prophylaxis and/or for blocking malaria transmission to benefit both, the individual consumer and the community at large. Neem represents a good candidate for this purpose due to its inhibitory effects on the parasite stages that cause the clinical manifestations of malaria and on those responsible for infection in the vector. Furthermore, neem secondary metabolites have been shown to interfere with various physiological processes in insect vectors. This study was undertaken to assess the impact of the standardised neem extract NeemAzal® on the fitness of the malaria vector Anopheles stephensi following repeated exposure to the product through consecutive blood meals on treated mice. Methods: Batches of An. stephensi mosquitoes were offered 5 consecutive blood meals on female BALB/c mice treated with NeemAzal® at an azadirachtin A concentration of 60, 105 or 150 mg/kg. The blood feeding capacity was estimated by measuring the haematin content of the rectal fluid excreted by the mosquitoes during feeding. The number of eggs laid was estimated by image analysis and their hatchability assessed by direct observations. Results: A dose and frequency dependent impact of NeemAzal® treatment on the mosquito feeding capacity, oviposition and egg hatchability was demonstrated. In the 150 mg/kg treatment group, the mosquito feeding capacity was reduced by 50% already at the second blood meal and by 50 to 80% in all treatment groups at the fifth blood meal. Consequently, a 50 – 65% reduction in the number of eggs laid per female mosquito was observed after the fifth blood meal in all treatment groups. Similarly, after the fifth treated blood meal exposure, hatchability was found to be reduced by 62% and 70% in the 105 and 150 mg/kg group respectively. Conclusions: The findings of this study, taken together with the accumulated knowledge on neem open the challenging prospects of designing neem-based formulations as multi-target phytomedicines exhibiting preventive, parasite transmission-blocking as well as anti-vectorial properties. Keywords: Malaria, Vectors, Neem, Azadirachtin, Transmission-blocking, Anti-vectoria

Just Click Here : A Brief Glance at Absurd Electronic Contracts and the Law Failing to Protect Consumers

As e-commerce explodes around the world, consumers’ rights have been left behind. Before the completion of virtually every transaction on the Internet, the onus is placed on consumers to read and agree to an onslaught of terms and conditions. Often hidden in the middle of this extremely lengthy list of terms are massive exemption and limitation of liability clauses that deny consumers most if not all of their rights as “equal” trading partners. The common law principle that all onerous clauses in a contract need to be brought to the attention of the consumer for them to be binding seems to have been lost with the invention of the “click here to agree” button for signing online contracts. As the courts in Canada have not provided clear guidance on this issue thus far, other means must be pursued in order to protect consumers from the near-tyrannical control of unencumbered electronic standard form contracts in e-commerce. This paper will describe the principle of sufficiency of notice as it applies to paper contracts, and then contrast it with the newer jurisprudence that has refused to apply the principle to electronic contracts. The reasons for the refusal will be explored, followed by an examination of why the principle of sufficiency of notice needs to be applied and strengthened to respond to the increasingly onerous provisions hidden in electronic contracts. Finally, some other options for achieving the goal of consumer protection from hidden onerous clauses will be briefly explored. These other options include introducing stiffer consumer protection legislation domestically, the creation of international treaties, developing voluntary standards of contracting, and relying on Internet self-regulation

Novel, Meso-Substituted Cationic Porphyrin Molecule for Photo-Mediated Larval Control of the Dengue Vector Aedes aegypti

Dengue is a life-threatening viral disease of growing importance, transmitted by Aedes mosquito vectors. The control of mosquito larvae is crucial to contain or prevent disease outbreaks, and the discovery of new larvicides able to increase the efficacy and the flexibility of the vector control approach is highly desirable. Porphyrins are a class of molecules which generate reactive oxygen species if excited by visible light, thus inducing oxidative cell damage and cell death. In this study we aimed at assessing the potential of this photo-mediated cytotoxic mechanism to kill Aedes (Stegomyia) aegypti mosquito larvae. The selected porphyrin molecule, meso-tri(N-methylpyridyl),meso-mono(N-tetradecylpyridyl)porphine (C14 for simplicity), killed the larvae at doses lower than 1 µM, and at light intensities 50–100 times lower than those typical of natural sunlight, by damaging their intestinal tissues. The physicochemical properties of C14 make it easily adsorbed into organic material, and we exploited this feature to prepare an ‘insecticidal food’ which efficiently killed the larvae and remained active for at least 14 days after its dispersion in water. This study demonstrated that photo-sensitizing agents are promising tools for the development of new larvicides against mosquito vectors of dengue and other human and animal diseases

PROBING GRAVITY IN NEO'S WITH HIGH-ACCURACY LASER-RANGED TEST MASSES

Received 9 August 2006Communicated by S. G. TuryshevGravity can be studied in detail in near Earth orbits NEO's using laser-ranged testmasses tracked with few-mm accuracy by ILRS. The two LAGEOS satellites have beenused to measure frame dragging (a truly rotational effect predicted by GR) with a 10%error. A new mission and an optimized, second generation satellite, LARES (I. CiufoliniPI), is in preparation to reach an accuracy of 1% or less on frame dragging, to measuresome PPN parameters, to test the

L’indagine macrosismica: metodologia, parametri del terremoto, questioni aperte

Subito dopo l’evento del 6 aprile 2009, come di consueto è stata realizzata una lunga e complessa indagine macrosismica, promossa dal gruppo operativo QUEST, che ha avuto inizialmente l’obiettivo di delimitare l’area di danneggiamento, a supporto delle attività di pronto intervento della Protezione Civile, e successivamente quello di classificare nel modo più accurato e capillare possibile, gli effetti prodotti dall’evento, particolarmente nelle aree danneggiate. A questo scopo è stata prodotta una stima utilizzando la scala MCS (Sieberg, 1930); in un secondo momento è stata rifinita l’indagine per una cinquantina di località dell’area maggiormente danneggiata (Is MCS>VII), raccogliendo ed elaborando i dati in termini di scala macrosismica EMS98 (Grünthal, 1998). Per la complessità e la dimensione dei problemi affrontati, questo terremoto ha costituito un banco di prova di grande importanza per la macrosismologia italiana. In questo testo viene descritto il lavoro realizzato, discutendo in particolare alcuni aspetti che hanno messo alla prova le metodologie di indagine tradizionali (sistematiche irregolarità degli insediamenti monitorati, forti divergenze degli scenari di danno rispetto a quelli previsti dalle scale, difficile comparabilità con scenari storici, ecc.) e presentandone i risultati, in relazione ai parametri epicentrali che ne risultano e il loro contributo più diretto alla comprensione complessiva della sismicità dell’area