We associate to each Boolean language complexity class C the algebraic class a·C consisting of families of polynomials {fn} for which the evaluation problem over Z is in C. We prove the following lower bound and randomness-to-hardness results: 1. If polynomial identity testing (PIT) is in NSUBEXP then a·NEXP does not have poly size constant-free arithmetic circuits. 2. a·NEXP does not have poly...

We study the problem of approximating a function from a separable metric space D to a separable metric space Z by functions g from D to Z which have the property there is no set E of power 2** such that g is a homeomorphism of E onto g(E). Theorem 1 asserts that any one to one function may be approximated by such a function. Numerous continuous functions may be approximated by such functions wh...

Synchrotron-based high-resolution photoemission, X-ray absorption near-edge spectroscopy, and first-principles density functional (DF) slab calculations were used to study the interaction of NO(2) with a TiO(2)(110) single crystal and powders of titania. The main product of the adsorption of NO(2) on TiO(2)(110) is surface nitrate with a small amount of chemisorbed NO(2). A similar result is ob...

We performed incubation experiments with 15N-labeled nitrogen compounds to investigate the vertical distribution of pathways of N2 production through the suboxic zone of the central Black Sea and the impact of oxygen and sulfide on the anammox process. Anammox rates increased with depth through the upper suboxic zone and reached a maximum of ,11 nmol N2 L21 d21 at the sharp interface between ni...

The unique active site of flavo-diiron proteins (FDPs) consists of a nonheme diiron-carboxylate site proximal to a flavin mononucleotide (FMN) cofactor. FDPs serve as the terminal components for reductive scavenging of dioxygen or nitric oxide to combat oxidative or nitrosative stress in bacteria, archaea, and some protozoan parasites. Nitric oxide is reduced to nitrous oxide by the four-electr...

Denitrification is an anaerobic process performed by several soil bacteria as an alternative to aerobic respiration. A key-step in denitrification (the N-Nbond is made) is catalyzed by nitric oxide reductase (NOR); 2NO + 2e + 2H → N2O + H2O. NOR from Paracoccus denitrificans is a member of the heme copper oxidase superfamily (HCuOs), where the mitochondrial cytochrome c oxidase is the classical...

Fifty-seven years after NO(x) (NO + NO(2)) were identified as essential components of photochemical smog, atmospheric chemical models fail to correctly predict *OH/HO(2)* concentrations under NO(x)-rich conditions. This deficiency is due, in part, to the uncertain rates and mechanism for the reactive dissolution of NO(2)(g) (2NO(2) + H(2)O = NO(3)(-) + H(+) + HONO) in fog and aerosol droplets. ...

The O((1)D) + N(2)O → 2NO(X (2)Π) reaction has been studied in a molecular beam experiment in which O(3) and N(2)O were coexpanded. The precursor O((1)D) was prepared by O(3) photodissociation at 266 nm, and the NO(X (2)Π) molecules born from the reaction as the O((1)D) recoiled out of the beam were detected by 1+1 REMPI over the 220-246 nm probe laser wavelength range. The resulting spectrum w...