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Indoor acids and bases.
Numerous acids and bases influence indoor air quality. The most abundant of these species are CO2 (acidic) and NH3 (basic), both emitted by building occupants. Other prominent inorganic acids are HNO3 , HONO, SO2 , H2 SO4 , HCl, and HOCl. Prominent organic acids include formic, acetic, and lactic; nicotine is a noteworthy organic base. Sources of N-, S-, and Cl-containing acids can include ventilation from outdoors, indoor combustion, consumer product use, and chemical reactions. Organic acids are commonly more abundant indoors than outdoors, with indoor sources including occupants, wood, and cooking. Beyond NH3 and nicotine, other noteworthy bases include inorganic and organic amines. Acids and bases partition indoors among the gas-phase, airborne particles, bulk water, and surfaces; relevant thermodynamic parameters governing the partitioning are the acid-dissociation constant (Ka ), Henry's law constant (KH ), and the octanol-air partition coefficient (Koa ). Condensed-phase water strongly influences the fate of indoor acids and bases and is also a medium for chemical interactions. Indoor surfaces can be large reservoirs of acids and bases. This extensive review of the state of knowledge establishes a foundation for future inquiry to better understand how acids and bases influence the suitability of indoor environments for occupants, cultural artifacts, and sensitive equipment
Numerical Calculation of Bessel Functions
A new computational procedure is offered to provide simple, accurate and
flexible methods for using modern computers to give numerical evaluations of
the various Bessel functions. The Trapezoidal Rule, applied to suitable
integral representations, may become the method of choice for evaluation of the
many Special Functions of mathematical physics.Comment: 10 page
The Low-z Intergalactic Medium. III. HI and Metal Absorbers at z<0.4
We conduct an ultraviolet (HST and FUSE) spectroscopic survey of HI (Lyman
lines) and seven metal ions (OVI, NV, CIV, CIII, SiIV, SiIII, FeIII) in the
low-redshift intergalactic medium (IGM) at z<0.4. We analyzed 650 Lya absorbers
over redshift pathlength Delta z=5.27, detecting numerous absorbers: 83 OVI
systems, 39 CIII, 53 SiIII, 24 CIV, 24 NV, and so on. Our survey yields
distributions in column density and estimates of the IGM baryon content and
metallicities of C, N, O in the IGM. In the low-z IGM, we have accounted for
~40% of the baryons: 30% in the photoionized Lya forest and 10% in the
(T=10^5-6 K) warm-hot intergalactic medium (WHIM) traced by OVI. Statistical
metallicities of C, N, O ions are consistent with the canonical (z=0) value of
10% solar, with considerable scatter. Improved statistics for weak OVI
absorbers allows us to estimate Omega_WHIM/Omega_b=0.073+-0.008 down to
logN_OVI=13.4. NV absorption is well-correlated with OVI and both ions show
similarly steep power-law indices dN/dz N^-beta with beta_OVI beta_NV 2 while
beta_HI=1.7. We conclude that OVI and NV are reliable tracers of the portion of
the WHIM at T=10^5-6 K. CIV may be present in both collisional and photoionized
phases; N_CIV correlates poorly with both N_HI and N_OVI and
beta_HI<beta_CIV<beta_OVI. The ions CIII, SiIII, and SiIV are well correlated
with HI and show patterns typical of photoionization. Adjacent ion stages of
the same element (CIII/IV and SiIII/IV) provide useful constraints on the
photoionization parameter, logU=-1.5+-0.5. Comparison of SiIV and CIV with
high-z surveys shows a modest increase in line density, consistent with
increasing IGM metallicity at recent epochs.Comment: Submitted to ApJ, 27 pages in ApJ format (figure and discussion
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An intrinsic homotopy for intersecting algebraic varieties
Recently we developed a diagonal homotopy method to compute a numerical
representation of all positive dimensional components in the intersection of
two irreducible algebraic sets. In this paper, we rewrite this diagonal
homotopy in intrinsic coordinates, which reduces the number of variables,
typically in half. This has the potential to save a significant amount of
computation, especially in the iterative solving portion of the homotopy path
tracker. There numerical experiments all show a speedup of about a factor two
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