Supersymmetric AdS Backgrounds in String and M-theory

We first present a short review of general supersymmetric compactifications in string and M-theory using the language of G-structures and intrinsic torsion. We then summarize recent work on the generic conditions for supersymmetric AdS_5 backgrounds in M-theory and the construction of classes of new solutions. Turning to AdS_5 compactifications in type IIB, we summarize the construction of an infinite class of new Sasaki-Einstein manifolds in dimension 2k+3 given a positive curvature Kahler-Einstein base manifold in dimension 2k. For k=1 these describe new supergravity duals for N=1 superconformal field theories with both rational and irrational R-charges and central charge. We also present a generalization of this construction, that has not appeared elsewhere in the literature, to the case where the base is a product of Kahler-Einstein manifolds.Comment: LaTeX, 35 pages, to appear in the proceedings of the 73rd Meeting between Physicists and Mathematicians "(A)dS/CFT correspondence", Strasbourg, September 11-13, 200

Sasaki-Einstein Metrics on S^2 x S^3

We present a countably infinite number of new explicit co-homogeneity one Sasaki-Einstein metrics on S^2 x S^3, in both the quasi-regular and irregular classes. These give rise to new solutions of type IIB supergravity which are expected to be dual to N=1 superconformal field theories in four-dimensions with compact or non-compact R-symmetry and rational or irrational central charges, respectively.Comment: 20 pages. v2: references added, typos corrected. v3: minor typos correcte

COMBINING SUSTAINABLE VALUE STREAM MAPPING AND SIMULATION TO ASSESS MANUFACTURING SUPPLY CHAIN NETWORK PERFORMANCE

Sustainable Value Stream Mapping (Sus-VSM) builds upon traditional VSM to capture additional sustainability aspects of the product flow, such as environmental and societal aspects. This work presents research to expand the utility of Sus-VSM to supply chain networks, develop a general approach towards improving supply chain sustainability, and examine the benefits of implementing simulation and a design of experiments (DOE) style analysis. Metrics are identified to assess economic, environmental, and societal sustainability for supply chain networks and visual symbols are developed for the Supply Chain Sus-VSM (SC Sus-VSM) to allow users to easily identify locations where sustainability can be improved. A discrete event simulation (DES) model is developed to simulate the supply chain, allowing easier creation of future state maps, which are used to identify locations for sustainability improvement. A scoring methodology and DOE-style analysis are developed to collect more information from the supply chain. Results from the case study show that the SC Sus-VSM meets the goals desired, and that the DES model aids the goals of the map. It is also indicated that interventions in the supply chain should first focus on economic improvements, followed by societal and then environmental improvements to achieve the greatest supply chain sustainability

Fish, Polychlorinated Biphenyls (PCBs) and Natural Resource Injury

The Natural Resource Damage Assessment (NRDA) program is authorized by the Comprehensive Environmental Response Compensation and Liability Act (CERCLA) and the Oil Pollution Act (OPA) to pursue compensation for injury to, or destruction and loss of, natural resources. Fish are an important natural resource present in almost all aquatic ecosystems. Polychlorinated biphenyls (PCBs) are a hazardous substance and have been shown to cause harm to fish (and fish-eating animals). A series of investigations were conducted to determine if injury had occurred to creek chub (Semotilus atromaculatus) and in one study, the fish community that creek chubs were a part of, at several PCB-contaminated study locations. We examined: hepatic condition and oxidative stress enzymes; a comprehensive look at reproductive condition; age and growth; and several metrics of fish community structure and function. Although the determination of hepatic oxidative stress is a response to PCBs, this in and of itself is not considered injury. However, it is a good biomarker of potential injury especially in the presence of other injuries, like reproductive failure. Consistent with the PCB toxicity literature, we consider hepatomegaly and lipidosis injuries that result from PCB exposure. Given that other common factors can also cause lipidosis, this is not an effective injury assessment tool. The age and growth analysis shows significantly reduced survivorship in females at the PCB sites; this is clearly an injury. Aspects of creek chub reproduction have also been adversely impacted: reduced vitellogenin (Vtg), altered sex steroid ratios, reduced fecundity, delayed/ impaired spawning of ova, and reduced / impaired testes maturation. Although not an injury per se, the reduced and seasonally altered pattern of the male secondary sex characteristic nuptial tubercles provides another line of evidence that neuroendocrine disruption is occurring at the PCB-contaminated stream sites. An assessment of the fish community at these PCB-contaminated streams also indicated that growth and survival were issues for the entire fish community. From Frye\u27s standard of evidence [Frye v. United States, 293 F.1013 (D.C. Cir. 1923)], much of this work would have been extremely useful to trustees in court. What we found would be generally acceptable in our professional sphere. But scientists and lawyers look at facts differently: same language, same word, different meaning. The science of reproduction impacts is very complicated, and some aspects (i.e. neuroendocrine disruption) while clearly injury, are too complicated to prevail in the courtroom. The impacts to reproduction, including reduced vitellogenin (Vtg), reduced fecundity and delayed/ impaired spawning of ova have significant ecosystem consequences. Growth effects that follow a non-monotonic non-standard dose response curve would do poorly in court. While reduced survivorship should easily be translated to the injury known as death , nothing in court is certain. Because it is extremely difficult to put a value on natural resources, it is very important to do whatever can be done early on to avoid litigation. A complete win on injury determinations (albeit unlikely), could still result in little or no restoration relief

A New Infinite Class of Sasaki-Einstein Manifolds

We show that for every positive curvature Kahler-Einstein manifold in dimension 2n there is a countably infinite class of associated Sasaki-Einstein manifolds X_{2n+3} in dimension 2n+3. When n=1 we recover a recently discovered family of supersymmetric AdS_5 x X_5 solutions of type IIB string theory, while when n=2 we obtain new supersymmetric AdS_4 x X_7 solutions of D=11 supergravity. Both are expected to provide new supergravity duals of superconformal field theories.Comment: 12 pages. v2: minor typos corrected, comment on generalisation to product base manifold

AdS_5 Solutions of Type IIB Supergravity and Generalized Complex Geometry

We use the formalism of generalized geometry to study the generic supersymmetric AdS_5 solutions of type IIB supergravity that are dual to N=1 superconformal field theories (SCFTs) in d=4. Such solutions have an associated six-dimensional generalized complex cone geometry that is an extension of Calabi-Yau cone geometry. We identify generalized vector fields dual to the dilatation and R-symmetry of the dual SCFT and show that they are generalized holomorphic on the cone. We carry out a generalized reduction of the cone to a transverse four-dimensional space and show that this is also a generalized complex geometry, which is an extension of Kahler-Einstein geometry. Remarkably, provided the five-form flux is non-vanishing, the cone is symplectic. The symplectic structure can be used to obtain Duistermaat-Heckman type integrals for the central charge of the dual SCFT and the conformal dimensions of operators dual to BPS wrapped D3-branes. We illustrate these results using the Pilch-Warner solution.Comment: 56 pages; v2: minor changes, version to be published in Commun. Math. Phy

Extracellular Nucleotides Inhibit Insulin Receptor Signaling, Stimulate Autophagy and Control Lipoprotein Secretion

Hyperglycemia is associated with abnormal plasma lipoprotein metabolism and with an elevation in circulating nucleotide levels. We evaluated how extracellular nucleotides may act to perturb hepatic lipoprotein secretion. Adenosine diphosphate (ADP) (>10 µM) acts like a proteasomal inhibitor to stimulate apoB100 secretion and inhibit apoA-I secretion from human liver cells at 4 h and 24 h. ADP blocks apoA-I secretion by stimulating autophagy. The nucleotide increases cellular levels of the autophagosome marker, LC3-II, and increases co-localization of LC3 with apoA-I in punctate autophagosomes. ADP affects autophagy and apoA-I secretion through P2Y13. Overexpression of P2Y13 increases cellular LC3-II levels by ∼50% and blocks induction of apoA-I secretion. Conversely, a siRNA-induced reduction in P2Y13 protein expression of 50% causes a similar reduction in cellular LC3-II levels and a 3-fold stimulation in apoA-I secretion. P2Y13 gene silencing blocks the effects of ADP on autophagy and apoA-I secretion. A reduction in P2Y13 expression suppresses ERK1/2 phosphorylation, increases the phosphorylation of IR-β and protein kinase B (Akt) >3-fold, and blocks the inhibition of Akt phosphorylation by TNFα and ADP. Conversely, increasing P2Y13 expression significantly inhibits insulin-induced phosphorylation of insulin receptor (IR-β) and Akt, similar to that observed after treatment with ADP. Nucleotides therefore act through P2Y13, ERK1/2 and insulin receptor signaling to stimulate autophagy and affect hepatic lipoprotein secretion