1,070 research outputs found
Scalable and Cost Efficient Algorithms for Virtual CDN Migration
Virtual Content Delivery Network (vCDN) migration is necessary to optimize
the use of resources and improve the performance of the overall SDN/NFV-based
CDN function in terms of network operator cost reduction and high streaming
quality. It requires intelligent and enticed joint SDN/NFV migration algorithms
due to the evident huge amount of traffic to be delivered to end customers of
the network. In this paper, two approaches for finding the optimal and near
optimal path placement(s) and vCDN migration(s) are proposed (OPAC and HPAC).
Moreover, several scenarios are considered to quantify the OPAC and HPAC
behaviors and to compare their efficiency in terms of migration cost, migration
time, vCDN replication number, and other cost factors. Then, they are
implemented and evaluated under different network scales. Finally, the proposed
algorithms are integrated in an SDN/NFV framework. Index Terms: vCDN; SDN/NFV
Optimization; Migration Algorithms; Scalability Algorithms.Comment: 9 pages, 11 figures, 4 tableaux, conference Local Computer Networks
(LCN), class
Foreign and U.S Educated Faculty Membersâ Views on What Constitutes Excellent Teaching: Effects of Gender and Discipline
This study identifies views of foreign-educated faculty who teach in American universities on what constitutes excellence in teaching based on different demographics using the online version of the Teacher Behavior Checklist. Faculty from 14 institutions within the Southern Regional Educational Board (SREB) were asked to rank the top 10 of 28 teacher qualities of excellent teaching. The final faculty sample consisted of 448 participants, of which 309 were United States-educated (US-educated), and 139 were foreign-educated. The majority of the foreign-educated faculty were from Asia and Europe. Results showed that both US- and foreign-educated faculty agreed on eight qualities as the most important for excellent teaching, although in different order. âKnowledgeableâ and âenthusiasticâ were generally ranked the number 1 and 2 top qualities. Foreign-educated faculty tended to rank âconfident,â âeffective communicator,â and âencourages and caresâ significantly higher than US-educated faculty. There was a statistically significant difference between US- and foreign-educated faculty in ranking the top qualities between and within demographic characteristics (that is, gender and discipline). This study provides a significant contribution to the literature on perceived qualities of excellent teaching between foreign- and US-educated faculty as well as important information for higher education administrators responsible for educational development
Optimization of Lipid Extraction From Municipal Scum Sludge for Biodiesel Production Using Statistical Approach
Design of Experiment (DoE) as a statistical method was applied for optimizing lipid extraction conditions from scum sludge. Four different extraction variables were optimized namely methanol to hexane ratio (%), solvent to sludge ratio (ml/g), temperature (oC), and extraction time (h). Process optimization was conducted through three main steps: 1) 2k factorial screening design; 2) Steepest ascent method; and 3) Box-Behnken design and response surface method. Based on 2k factorial screening design, methanol to hexane ratio, solvent to sludge ratio and temperature were identified as highly significant variables affecting lipid extraction from scum sludge. Based on screening results, the steepest ascent method was used followed by Box-Behnken design and Response Surface Method (RSM) were then applied for optimization. The maximum extracted lipid of 29.4% (wt lipid/wt dry sludge- %) was achieved at 40% methanol to hexane ratio (%), 40 solvent to sludge ratio (ml/g), 90oC and 6 hours extraction time. The results revealed that lipid extraction increases with reducing the methanol to hexane ratio, increasing solvent to sludge ratio and increasing temperature The results demonstrated the potentiality of scum sludge for biodiesel production from scum sludge compared with the amount of lipid extracted from primary and secondary sludge reported by other studies.Article History: Received Feb 16th 2017; Received in revised form May 5th 2017; Accepted June 4th 2017; Available onlineHow to Cite This Article: Ibrahim, S.N.H, and Hamza, E.A. (2017). Optimization of Lipid Extraction from Municipal Scum Sludge for Biodiesel Production Using Statistical Approach. International Journal of Renewable Energy Development, 6(2), 171-179.https://doi.org/10.14710/ijred.6.2.171-17
Gasdermin pores permeabilize mitochondria to augment caspase-3 activation during apoptosis and inflammasome activation.
Gasdermin E (GSDME/DFNA5) cleavage by caspase-3 liberates the GSDME-N domain, which mediates pyroptosis by forming pores in the plasma membrane. Here we show that GSDME-N also permeabilizes the mitochondrial membrane, releasing cytochrome c and activating the apoptosome. Cytochrome c release and caspase-3 activation in response to intrinsic and extrinsic apoptotic stimuli are significantly reduced in GSDME-deficient cells comparing with wild type cells. GSDME deficiency also accelerates cell growth in culture and in a mouse model of melanoma. Phosphomimetic mutation of the highly conserved phosphorylatable Thr6 residue of GSDME, inhibits its pore-forming activity, thus uncovering a potential mechanism by which GSDME might be regulated. Like GSDME-N, inflammasome-generated gasdermin D-N (GSDMD-N), can also permeabilize the mitochondria linking inflammasome activation to downstream activation of the apoptosome. Collectively, our results point to a role of gasdermin proteins in targeting the mitochondria to promote cytochrome c release to augment the mitochondrial apoptotic pathway
Properties of Pb(Zr,Ti)O ultrathin films under stress-free and open-circuit electrical boundary conditions
A first-principles-based scheme is developed to simulate properties of (001)
PbO-terminated Pb(ZrTi)O thin films that are under
stress-free and open-circuit boundary conditions. Their low-temperature
spontaneous polarization never vanishes down to the minimal thickness, and
continuously rotates between the in-plane and directions when
varying the Ti composition around x=0.50. Such rotation dramatically enhances
piezoelectricity and dielectricity. Furthermore, the order of some phase
transitions changes when going from bulk to thin films.Comment: 11 pages, 3 figure
The structures of secretory and dimeric immunoglobulin A
Secretory (S) Immunoglobulin (Ig) A is the predominant mucosal antibody, which binds pathogens and commensal microbes. SIgA is a polymeric antibody, typically containing two copies of IgA that assemble with one joining-chain (JC) to form dimeric (d) IgA that is bound by the polymeric Ig-receptor ectodomain, called secretory component (SC). Here, we report the cryo-electron microscopy structures of murine SIgA and dIgA. Structures reveal two IgAs conjoined through four heavy-chain tailpieces and the JC that together form a ÎČ-sandwich-like fold. The two IgAs are bent and tilted with respect to each other, forming distinct concave and convex surfaces. In SIgA, SC is bound to one face, asymmetrically contacting both IgAs and JC. The bent and tilted arrangement of complex components limits the possible positions of both sets of antigen-binding fragments (Fabs) and preserves steric accessibility to receptor-binding sites, likely influencing antigen binding and effector functions
A malaria membrane skeletal protein is essential for normal morphogenesis, motility, and infectivity of sporozoites
Membrane skeletons are structural elements that provide mechanical support to the plasma membrane and define cell shape. Here, we identify and characterize a putative protein component of the membrane skeleton of the malaria parasite. The protein, named PbIMC1a, is the structural orthologue of the Toxoplasma gondii inner membrane complex protein 1 (TgIMC1), a component of the membrane skeleton in tachyzoites. Using targeted gene disruption in the rodent malaria species Plasmodium berghei, we show that PbIMC1a is involved in sporozoite development, is necessary for providing normal sporozoite cell shape and mechanical stability, and is essential for sporozoite infectivity in insect and vertebrate hosts. Knockout of PbIMC1a protein expression reduces, but does not abolish, sporozoite gliding locomotion. We identify a family of proteins related to PbIMC1a in Plasmodium and other apicomplexan parasites. These results provide new functional insight in the role of membrane skeletons in apicomplexan parasite biology
Atypical plug formation in internal elastoviscoplastic fluid flows over a non-smooth topology
An experimental and computational investigation of the internal flow of
elastoviscoplastic fluids over non-smooth topologies is presented in two
complimentary studies. In the first study, we visualize the creeping flow of a
Carbopol gel over a cavity embedded in a thin slot using Optical Coherence
Tomography (OCT) and confocal microscopy. We measure the size and shape of the
plug as a function of Bingham and Weissenberg numbers. An asymmetry in the plug
shape is observed which is also evident in our second study -- numerical
simulations using adaptive finite element method based upon an augmented
Lagrangian scheme. We quantify the asymmetry and present the results as a
function of the product of the Weissenberg and Bingham numbers which collapse
onto a single curve for each of these geometries. These findings underscore the
theoretical underpinnings of the synergy between elasticity and plasticity of
these complex fluids
The TLR4 D299G and T399I SNPs Are Constitutively Active to Up-Regulate Expression of Trif-Dependent Genes
Peer reviewedPublisher PD
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