A min-max framework for CPU resource provisioning in virtualized servers using ℋ∞ Filters

Dynamic resource provisioning for virtualized server applications is integral to achieve efficient cloud and green computing. In server applications unpredicted workload changes occur frequently. Resource adaptation of the virtual hosts should dynamically scale to the updated demands (cloud computing) as well as co-locate applications to save on energy consumption (green computing). Most importantly, resource transitions during workload surges should occur while minimizing the expected loss due to mismatches of the resource predictions and actual workload demands. Our approach is to minimize the maximum expected loss using the same techniques as in two-person zero-sum games. We develop an H∞ filter that minimizes the worst-case estimation and allocate resources fast. Through simulations our H∞ filter demonstrates its effectiveness and good performance when compared against Kalman-based controllers

Resource Provisioning for Multi-Tier Virtualized Server Applications

Virtualizing the x86-based data center creates a dynamic environment for server application deployment and resource sharing. Resource management in this environment is challenging as applications are under fluctuating workloads causing diverse resource demands across their tiers. Resource allocation adaptation is essential for high performance machine utilization. This paper presents feedback controllers that dynamically adjust the CPU allocations of multi-tier applications in order to adapt to workload changes by considering the resource coupling between utilizations of application components. Our experimental evaluation on a virtualized 3-tier Rubis server application shows that our techniques work effectively

Network traffic flow optimization under performance constraints

In this paper, a model-based perimeter control policy for large-scale urban vehicular networks is proposed. Assuming a homogeneously loaded vehicle network and the existence of a well-posed Network Fundamental Diagram (NFD), we describe a protected network throughout its aggregated dynamics including nonlinear exit flow characteristics. Within this framework of constrained optimal boundary flow gating, two main performance metrics are considered: (a) first, connected to the NFD, the concept of average network travel time and delay as a performance metric is defined; (b) second, at boundaries, we take into account additional external network queue dynamics governed by uncontrolled inflow demands. External queue capacities in terms of finite-link lengths are used as the second performance metric. Hence, the corresponding performance requirement is an upper bound of external queues. While external queues represent vehicles waiting to enter the protected network, internal queue describes the protected network’s aggregated behavior. By controlling the number of vehicles joining the internal queue from the external ones, herewith a network traffic flow maximization solution subject to the internal and external dynamics and their performance constraints is developed. The originally non-convex optimization problem is transformed to a numerically efficiently convex one by relaxing the performance constraints into time-dependent state boundaries. The control solution can be interpreted as a mechanism which transforms the unknown arrival process governing the number of vehicles entering the network to a regulated process, such that prescribed performance requirements on travel time in the network and upper bound on the external queue are satisfied. Comparative numerical simulation studies on a microscopic traffic simulator are carried out to show the benefits of the proposed method

Observation of a Triangular to Square Flux Lattice Phase Transition in YBCO

We have used the technique of small-angle neutron scattering to observe magnetic flux lines directly in an YBCO single crystal at fields higher than previously reported. For field directions close to perpendicular to the CuO2 planes, we find that the flux lattice structure changes smoothly from a distorted triangular co-ordination to nearly perfectly square as the magnetic induction approaches 11 T. The orientation of the square flux lattice is as expected from recent d-wave theories, but is 45 deg from that recently observed in LSCO

The topological dimension of type I C*-algebras

While there is only one natural dimension concept for separable, metric spaces, the theory of dimension in noncommutative topology ramifies into different important concepts. To accommodate this, we introduce the abstract notion of a noncommutative dimension theory by proposing a natural set of axioms. These axioms are inspired by properties of commutative dimension theory, and they are for instance satisfied by the real and stable rank, the decomposition rank and the nuclear dimension. We add another theory to this list by showing that the topological dimension, as introduced by Brown and Pedersen, is a noncommutative dimension theory of type I C*-algebras. We also give estimates of the real and stable rank of a type I C*-algebra in terms of its topological dimension.Comment: 20 pages; minor correction

D-XY Critical Behavior in Cuprate Superconductors

We outline the universal and finite temperature critical properties of the 3D-XY model, extended to anisotropic extreme type-II superconductors, as well as the universal quantum critical properties in 2D. On this basis we review: (i) the mounting evidence for 3D-XY behavior in optimally doped cuprate superconductors and the 3D to 2D crossover in the underdoped regime; (ii) the finite size limitations imposed by inhomogeneities; (iii) the experimental evidence for a 2D-XY quantum critical point in the underdoped limit, where the superconductor to insulator transition occurs; (iv) the emerging implications and constraints for microscopic models.Comment: 5 pages, 6 figure

MRAP deficiency impairs adrenal progenitor cell differentiation and gland zonation

Melanocortin 2 receptor accessory protein (MRAP) is a single transmembrane domain accessory protein and a critical component of the hypothamo-pituitary-adrenal axis. MRAP is highly expressed in the adrenal gland and is essential for adrenocorticotropin hormone (ACTH) receptor expression and function. Human loss-of-function mutations in MRAP cause familial glucocorticoid (GC) deficiency (FGD) type 2 (FGD2), whereby the adrenal gland fails to respond to ACTH and to produce cortisol. In this study, we generated Mrap-null mice to study the function of MRAP in vivo. We found that the vast majority of Mrap−/− mice died at birth but could be rescued by administration of corticosterone to pregnant dams. Surviving Mrap−/− mice developed isolated GC deficiency with normal mineralocorticoid and catecholamine production, recapitulating FGD2. The adrenal glands of adult Mrap−/− mice were small, with grossly impaired adrenal capsular morphology and cortex zonation. Progenitor cell differentiation was significantly impaired, with dysregulation of WNT4/β-catenin and sonic hedgehog pathways. These data demonstrate the roles of MRAP in both steroidogenesis and the regulation of adrenal cortex zonation. This is the first mouse model of isolated GC deficiency and reveals the role of MRAP in adrenal progenitor cell regulation and cortex zonatio

Strategies to Accelerate HIV Care and Antiretroviral Therapy Initiation After HIV Diagnosis: A Randomized Trial.

: Determine the effectiveness of strategies to increase linkage to care after testing HIV positive at mobile HIV testing in South Africa. : Unmasked randomized controlled trial. : Recruitment of adults testing HIV positive and not currently in HIV care occurred at 7 mobile HIV counseling and testing units in urban, periurban, and rural South Africa with those consenting randomized 1:1:1:1 into 1 of 4 arms. Three strategies were compared with standard of care (SOC): point-of-care CD4 count testing (POC CD4), POC CD4 plus longitudinal strengths-based counseling (care facilitation; CF), and POC CD4 plus transport reimbursement (transport). Participants were followed up telephonically and through clinic records and analyzed with an intention-to-treat analysis. : From March 2013 to October 2014, 2558 participants were enrolled, of whom 160 were excluded postrandomization. Compared with the SOC arm where 298 (50%) reported having entered care, linkage to care was 319 (52%) for POC CD4, hazard ratio (HR) 1.0 [95% confidence interval (CI): 0.89 to 1.2, P = 0.6]; 331 (55%) for CF, HR: 1.1 (95% CI: 0.84 to 1.3, P = 0.2); and 291 (49%) for transport, HR 0.97 (95% CI: 0.83 to 1.1, P = 0.7). Linkage to care verified with clinical records that occurred for 172 (29%) in the SOC arm; 187 (31%) in the POC CD4 arm, HR: 1.0 (95% CI: 0.86 to 1.3, P = 0.6); 225 (38%) in the CF arm, HR: 1.4 (95% CI: 1.1 to 1.7, P = 0.001); and 180 (31%) in the transport arm, HR: 1.1 (95% CI: 0.88 to 1.3, P = 0.5). : CF improved verified linkage to care from 29% to 38%.<br/

Downregulation of the Canonical WNT Signaling Pathway by TGF beta 1 Inhibits Photoreceptor Differentiation of Adult Human Muller Glia with Stem Cell Characteristics

Muller glia are responsible for the retina regeneration observed in zebrafish. Although the human retina harbors Muller glia with stem cell characteristics, there is no evidence that they regenerate the retina after disease or injury. Transforming growth factor-b (TGFb) and Wnt signaling regulate retinal neurogenesis and inflammation, but their roles in the neural differentiation of human Mu¨ller stem cells (hMSC) are not known. We examined hMSC lines in vitro for the expression of various Wnt signaling components and for their modulation by TGFb1, as well as the effect of this cytokine on the photoreceptor differentiation of these cells. Culture of hMSC with a combination of factors that induce photoreceptor differentiation of hMSC (FGF2, taurine, retinoic acid, and insulin-like growth factor type1; FTRI), markedly upregulated the expression of components of the canonical Wnt signaling pathway, including WNT2B, DKK1, and active b-CATENIN. Although FTRI did not modify mRNA expression of WNT5B, a component of the noncanonical/planar cell polarity Wnt pathway, it upregulated its secretion. Furthermore, TGFb1 not only decreased WNT2B expression, but also inhibited FTRI-induced photoreceptor differentiation of hMSC, as determined by expression of the photoreceptor markers NR2E3, RHODOPSIN, and RECOVERIN. Inhibition of TGFb1 signaling by an ALK5 inhibitor prevented TGFb1-induced changes in the expression of the two Wnt ligands examined. More importantly, inhibition of the canonical WNT signaling by XAV-939 prevented FTRI-induced photoreceptor differentiation. These observations suggest that TGFb may play a key role in preventing neural differentiation of hMSC and may constitute a potential target for induction of endogenous regeneration of the human retina

Perceived Realism of Pedestrian Crowds Trajectories in VR

Crowd simulation algorithms play an essential role in populating Virtual Reality (VR) environments with multiple autonomous humanoid agents. The generation of plausible trajectories can be a significant computational cost for real-time graphics engines, especially in untethered and mobile devices such as portable VR devices. Previous research explores the plausibility and realism of crowd simulations on desktop computers but fails to account the impact it has on immersion. This study explores how the realism of crowd trajectories affects the perceived immersion in VR. We do so by running a psychophysical experiment in which participants rate the realism of real/synthetic trajectories data, showing similar level of perceived realism