The Hardness of Embedding Grids and Walls

The dichotomy conjecture for the parameterized embedding problem states that the problem of deciding whether a given graph $G$ from some class $K$ of "pattern graphs" can be embedded into a given graph $H$ (that is, is isomorphic to a subgraph of $H$) is fixed-parameter tractable if $K$ is a class of graphs of bounded tree width and $W[1]$-complete otherwise. Towards this conjecture, we prove that the embedding problem is $W[1]$-complete if $K$ is the class of all grids or the class of all walls

Sources contributing to background surface ozone in the US Intermountain West

We quantify the sources contributing to background surface ozone concentrations in the US Intermountain West by using the GEOS-Chem chemical transport model with 1 / 2° × 2 / 3° horizontal resolution to interpret the Clean Air Status and Trends Network (CASTNet) ozone monitoring data for 2006–2008. We isolate contributions from lightning, wildfires, the stratosphere, and California pollution. Lightning emissions are constrained by observations and wildfire emissions are estimated from daily fire reports. We find that lightning increases mean surface ozone in summer by 10 ppbv in the Intermountain West, with moderate variability. Wildfire plumes generate high-ozone events in excess of 80 ppbv in GEOS-Chem, but CASTNet ozone observations in the Intermountain West show no enhancements during these events nor do they show evidence of regional fire influence. Models may overestimate ozone production in fresh fire plumes because of inadequate chemistry and grid-scale resolution. The highest ozone concentrations observed in the Intermountain West (> 75 ppbv) in spring are associated with stratospheric intrusions. The model captures the timing of these intrusions but not their magnitude, reflecting numerical diffusion intrinsic to Eulerian models. This can be corrected statistically through a relationship between model bias and the model-diagnosed magnitude of stratospheric influence; with this correction, models may still be useful to forecast and interpret high-ozone events from stratospheric intrusions. We show that discrepancy between models in diagnosing stratospheric influence is due in part to differences in definition, i.e., whether stratospheric ozone is diagnosed as produced in the stratosphere (GEOS-Chem definition) or as transported from above the tropopause. The latter definition can double the diagnosed stratospheric influence in surface air by labeling as "stratospheric" any ozone produced in the troposphere and temporarily transported to the stratosphere. California pollution influence in the Intermountain West frequently exceeds 10 ppbv but is generally not correlated with the highest ozone events

Effect of a commercial insecticidal soap on greenhouse whitefly (Hom: Aleyrod.) and its parasitoid, Encarsia formosa (Hym: Euloph.)

Safer’s Insecticidal Soap (IS) was topically applied at six concentrations to all growth stages of greenhouse whitefly as well as larvae and adults of the whitefly parasitoid, the eulophid wasp Encarsia formosa. IS at 0.5% ai caused more than 94% mortality of all whitefly larval stages and adults, and more than 82.5% mortalitv of whitefly pupae. Adults hatched from treated pupae occasionally showed altered development. E. formosa adults were more tolerant to IS than whitefly and 81.5% survived a 0.5% IS treatment. It was concluded that IS is an effective pesticide for greenhouse whitefly and should be integrated with E. formosa in greenhouse trials

Augmenting graphs to minimize the diameter

We study the problem of augmenting a weighted graph by inserting edges of bounded total cost while minimizing the diameter of the augmented graph. Our main result is an FPT 4-approximation algorithm for the problem.Comment: 15 pages, 3 figure

On The Power of Tree Projections: Structural Tractability of Enumerating CSP Solutions

The problem of deciding whether CSP instances admit solutions has been deeply studied in the literature, and several structural tractability results have been derived so far. However, constraint satisfaction comes in practice as a computation problem where the focus is either on finding one solution, or on enumerating all solutions, possibly projected to some given set of output variables. The paper investigates the structural tractability of the problem of enumerating (possibly projected) solutions, where tractability means here computable with polynomial delay (WPD), since in general exponentially many solutions may be computed. A general framework based on the notion of tree projection of hypergraphs is considered, which generalizes all known decomposition methods. Tractability results have been obtained both for classes of structures where output variables are part of their specification, and for classes of structures where computability WPD must be ensured for any possible set of output variables. These results are shown to be tight, by exhibiting dichotomies for classes of structures having bounded arity and where the tree decomposition method is considered

Multivariate Analyis of Swap Bribery

We consider the computational complexity of a problem modeling bribery in the context of voting systems. In the scenario of Swap Bribery, each voter assigns a certain price for swapping the positions of two consecutive candidates in his preference ranking. The question is whether it is possible, without exceeding a given budget, to bribe the voters in a way that the preferred candidate wins in the election. We initiate a parameterized and multivariate complexity analysis of Swap Bribery, focusing on the case of k-approval. We investigate how different cost functions affect the computational complexity of the problem. We identify a special case of k-approval for which the problem can be solved in polynomial time, whereas we prove NP-hardness for a slightly more general scenario. We obtain fixed-parameter tractability as well as W[1]-hardness results for certain natural parameters.Comment: 20 pages. Conference version published at IPEC 201

Activity of immunoproteasome inhibitor ONX-0914 in acute lymphoblastic leukemia expressing MLL–AF4 fusion protein

Proteasome inhibitors bortezomib and carfilzomib are approved for the treatment of multiple myeloma and mantle cell lymphoma and have demonstrated clinical efficacy for the treatment of acute lymphoblastic leukemia (ALL). The t(4;11)(q21;q23) chromosomal translocation that leads to the expression of MLL–AF4 fusion protein and confers a poor prognosis, is the major cause of infant ALL. This translocation sensitizes tumor cells to proteasome inhibitors, but toxicities of bortezomib and carfilzomib may limit their use in pediatric patients. Many of these toxicities are caused by on-target inhibition of proteasomes in non-lymphoid tissues (e.g., heart muscle, gut, testicles). We found that MLL–AF4 cells express high levels of lymphoid tissue-specific immunoproteasomes and are sensitive to pharmacologically relevant concentrations of specific immunoproteasome inhibitor ONX-0914, even in the presence of stromal cells. Inhibition of multiple active sites of the immunoproteasomes was required to achieve cytotoxicity against ALL. ONX-0914, an inhibitor of LMP7 (ß5i) and LMP2 (ß1i) sites of the immunoproteasome, and LU-102, inhibitor of proteasome ß2 sites, exhibited synergistic cytotoxicity. Treatment with ONX-0914 significantly delayed the growth of orthotopic ALL xenograft tumors in mice. T-cell ALL lines were also sensitive to pharmacologically relevant concentrations of ONX-0914. This study provides a strong rationale for testing clinical stage immunoproteasome inhibitors KZ-616 and M3258 in ALL

Robust Simulations and Significant Separations

We define and study a new notion of "robust simulations" between complexity classes which is intermediate between the traditional notions of infinitely-often and almost-everywhere, as well as a corresponding notion of "significant separations". A language L has a robust simulation in a complexity class C if there is a language in C which agrees with L on arbitrarily large polynomial stretches of input lengths. There is a significant separation of L from C if there is no robust simulation of L in C. The new notion of simulation is a cleaner and more natural notion of simulation than the infinitely-often notion. We show that various implications in complexity theory such as the collapse of PH if NP = P and the Karp-Lipton theorem have analogues for robust simulations. We then use these results to prove that most known separations in complexity theory, such as hierarchy theorems, fixed polynomial circuit lower bounds, time-space tradeoffs, and the theorems of Allender and Williams, can be strengthened to significant separations, though in each case, an almost everywhere separation is unknown. Proving our results requires several new ideas, including a completely different proof of the hierarchy theorem for non-deterministic polynomial time than the ones previously known

Normobaric hypoxia conditioning reduces blood pressure and normalizes nitric oxide synthesis in patients with arterial hypertension

,d Objectives Insufficient production and/or increased decomposition of the potent endogenous vasodilator nitric oxide plays an important role in development and progression of arterial hypertension and its complications. One of the most effective means of stimulating endogenous nitric oxide synthesis is controlled adaptation to hypoxia. This study examined the effect of a 20-day, intermittent, normobaric intermittent hypoxia conditioning (IHC) program on blood pressure (BP) and nitric oxide production in patients with stage 1 arterial hypertension. Methods The IHC sessions consisted of four to 10 cycles of alternating 3-min hypoxia (10% FIO 2 ) and 3-min room air breathing. BP was monitored for 24 h before and after IHC, and nitric oxide synthesis was evaluated by 24-h urinary excretion of the stable nitric oxide metabolites nitrate and nitrite. Results IHC increased nitric oxide synthesis and decreased BP in hypertensive patients to values similar to those of normotensive individuals. Significant inverse correlations were found between nitric oxide production and disease duration, SBP, and DBP. Moreover, IHC enhancement of nitric oxide synthesis was especially robust in patients with arterial hypertension of more than 5 years duration. The reduction in BP persisted for at least 3 months in 28 of 33 hypertensive patients. Conclusion IHC exerted a robust, persistent therapeutic effect and can be considered as an alternative, nonpharmacological treatment for patients with stage 1 arterial hypertension. The antihypertensive action of IHC is associated with normalization of nitric oxide production