Multi-agent quality of experience control

International Journal of Control, Automation and Systems - In the framework of the Future Internet, the aim of the Quality of Experience (QoE) Control functionalities is to track the personalized...     

Spinodal decomposition of binary mixtures with composition-dependent heat conductivities

Spinodal decomposition of a very viscous binary mixture is simulated, assuming that the fluid is bounded by two walls that are instantaneously quenched below the critical temperature. As usual, the mixture phase separates by forming dendritic structures whose size grows with time. While in conventional spinodal decomposition the morphology of the mixture is isotropic, here we show that, when the two components of the mixture have different heat conductivities, the configuration of the mixture may become anisotropic, depending on whether heat propagates slower or faster than mass. Specifically, for large heat conductivity differences, when the Lewis number is small, dendrites tend to align parallel to the isothermal lines; when it is large, dendrites progressively align perpendicular to the isothermal lines. This behavior can be explained observing that the morphology of the mixture is the result of two competing effects: on one hand, the mixture phase separates as soon as its temperature reaches its critical value and therefore it tends to follow the isothermal lines; on the other hand, the system tend to maximize heat transport, and therefore dendrites tend to span between the two quenched walls, i.e. perpendicular to the isothermal lines. This explanation is confirmed showing that when the imposed temperature difference between the side walls (and therefore the heat flux at equilibrium as well) is increased, dendrites tend to align across the walls more and more.     

The puzzling afterglow of GRB 050721: a rebrightening seen in the optical but not in the X-ray

We present here the analysis of the early and late multiwavelength afterglow emission, as observed by Swift a small robotic telescope and very large telescope (VLT). We compare early observations with late afterglow observations obtained with Swift and the VLT and we observe an intense rebrightening in the optical band at about 1 day after the burst, which is not present in the X-ray band. The lack of detection in X-ray of such a strong rebrightening at lower energies may be described with a variable external density profile. In such a scenario, the combined X-ray and optical observations allow us to derive that the matter density located at approximately 1017 cm from the burst is approximately a factor of 10 higher than in the inner region. This is the first time in which a rebrightening has been observed in the optical afterglow of a gamma-ray burst that is clearly absent in the X-ray afterglow.     

Effects of antihypertensive treatment on vasopressin secretion and on its osmoregulation in moderate hypertension

BACKGROUND: Changes in plasma osmolality and arterial pressure can affect the secretion of vasopressin (AVP). OBJECTIVE: To investigate the effect of a drug-induced lowering of the arterial pressure on the plasma concentration of AVP and on its osmoregulation in moderately severe uncomplicated hypertensives. DESIGN AND METHODS: A group of 33 moderate uncomplicated and untreated essential hypertensives of both sexes (mean age 48 +/- 1 years, average arterial pressure 171 +/- 3/108 +/- 2 mmHg) was studied. We measured AVP and other plasma and urine variables in 21 of them before and after administration of a hypertonic NaCl solution (100 mmol NaCl in 50 ml). Antihypertensive treatment with a single drug or, if necessary, with a combination of drugs was initiated for eight of these subjects and hypertonic saline administration was repeated after 1 month of treatment. The hypertonic stimulus was administered to the other 12 subjects after acute lowering of the arterial pressure by continuous intravenous infusion either of 0.3 mg clonidine in 100 ml (n = 6) or of 50 mg sodium nitroprusside in 250 ml (n = 6). RESULTS: Administration of hypertonic saline to untreated hypertensives increased their AVP level from 1.6 +/- 0.28 to 5.4 +/- 0.7 pg/ml (n = 21, P < 0.01). Their mean arterial pressure was lowered after pharmacological treatment for 1 month (n = 8) from 125 +/- 2 to 101 +/- 2 mmHg; their baseline AVP level remained unchanged (1.2 +/- 0.21 versus 0.9 +/- 0.25 pg/ml); after hypertonic saline had been administered to hypertensives with lowered arterial pressures, their AVP level increased to 6.0 +/- 1.03 pg/ml (P < 0.01). The AVP level in subjects whose MAP had been lowered acutely by administration of clonidine (n = 6) or of sodium nitroprusside (n = 6; on the average, from 132 +/- 3 to 110 +/- 4 mmHg) increased concurrently from 1.6 +/- 0.63 to 3.4 +/- 0.7 pg/ml (P < 0.05); after administration of the hypertonic saline the AVP level increased to 10.8 +/- 2.22 pg/ml (P < 0.01). This stimulated value was significantly (P < 0.01) higher than that observed after hypertonic saline had been administered to untreated hypertensives (5.4 +/- 0.7 pg/ml). CONCLUSIONS: Acute lowering of the arterial pressure in moderate essential hypertension appears to facilitate the secretion and osmoregulation of AVP. On the other hand, during prolonged antihypertensive treatment, baroreflex regulation of the secretion of AVP appears to be set at a lower operating point, thus exerting the same influence on the release of AVP as it did before antihypertensive treatment.     

Cell Contact with Endothelial Cells Favors the In Vitro Maintenance of Human Chronic Myeloid Leukemia Stem and Progenitor Cells

Chronic Myeloid Leukemia (CML) originates in a leukemic stem cell that resides in the bone marrow microenvironment, where they coexist with cellular and non-cellular elements. The vascular microenvironment has been identified as an important element in CML development since an increase in the vascularization has been suggested to be related with poor prognosis; also, using murine models, it has been reported that bone marrow endothelium can regulate the quiescence and proliferation of leukemic stem and progenitor cells. This observation, however, has not been evaluated in primary human cells. In this report, we used a co-culture of primitive (progenitor and stem) CML cells with endothelial colony forming cells (ECFC) as an in vitro model to evaluate the effects of the vascular microenvironment in the leukemic hematopoiesis. Our results show that this interaction allows the in vitro maintenance of primitive CML cells through an inflammatory microenvironment able to regulate the proliferation of progenitor cells and the permanence in a quiescent state of leukemic stem cells.     

A lexicographic approach to constrained MDP admission control

This paper proposes a reinforcement learning-based lexicographic approach to the call admission control problem in communication networks. The admission control problem is modelled as a multi-constrained Markov decision process. To overcome the problems of the standard approaches to the solution of constrained Markov decision processes, based on the linear programming formulation or on a Lagrangian approach, a multi-constraint lexicographic approach is defined, and an online implementation based on reinforcement learning techniques is proposed. Simulations validate the proposed approach.     

A dynamic load balancing algorithm for Quality of Service and mobility management in next generation home networks

Heterogeneity of connection technologies and nodes mobility open new challenges in home networks control strategies. Moreover, user’s needs are changing towards applications requiring high transmission speeds such as 3D gaming, enhanced interactivity and high definition video. Each of those applications puts several constraints on the network capabilities to guarantee requirements on the Quality of Service. In this paper we introduce an innovative concept based on fast load balancing algorithm operating on top of a convergence layer, in order to rapidly react to network changes and contemporaneously to satisfy strict application demands. We formulated the load balancing problem as a Multi-Commodity Flow and resolved it with a column generation approach using Lagrangian Relaxation and Dijkstra algorithm. The load balancing problem computational complexity is decreased with respect to state of the art load balancing solutions based on linear programming techniques. Proof of concept simulation results are reported.     

A Combinatorial Virtual Screening Approach Driving the Synthesis of 2,4-Thiazolidinedione-Based Molecules as New Dual mPGES-1/5-LO Inhibitors

Dual inhibition of microsomal prostaglandin E₂ synthase-1 (mPGES-1) and 5-lipoxygenase (5-LO), two key enzymes involved in pro-inflammatory eicosanoid biosynthesis, represents a new strategy for treating inflammatory disorders. Herein we report the discovery of 2,4-thiazolidinedione-based mPGES-1/5-LO dual inhibitors following a multidisciplinary protocol, involving virtual combinatorial screening, chemical synthesis, and validation of the biological activities for the selected compounds. Following the multicomponent-based chemical route for the decoration of the 2,4-thiazolidinedione core, a large library of virtual compounds was built (∼2.0×10⁴ items) and submitted to virtual screening. Nine selected molecules were synthesized and biologically evaluated, disclosing among them four compounds able to reduce the activity of both enzymes in the mid- and low- micromolar range of activities. These results are of interest for further expanding the chemical diversity around the 2,4-thiazolidinedione central core, facilitating the identification of novel anti-inflammatory agents endowed with a promising and safer pharmacological profile.     

Constipation and obesity: a statistical analysis

Constipation frequency was investigated among 1897 subjects (874 males and 1023 females), ranging in age from 6 to 70 years, chosen at random between city inhabitants and farmers. Bowel habit was studied in 966 obese patients (390 males and 576 females). The authors followed for the diagnosis of constipation either the commonest and restrictive criterion of the weekly bowel actions or the clinical one which implies also others parameters, like hard or small stools, difficulties of expulsion or feeling of incomplete evacuation after defecation. The statistical analysis showed that constipation frequency is 8.3% in obese patients and 1.5% in normal-weighting, according to weekly bowel actions criterion: the difference is statistically significative (p less than 0.001).