Diurnal cycle of deep tropical convection

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1992.Title as it appears in the M.I.T. Graduate List, Feb. 1992: Diurnal cycle of deep cloud cover in tropics.Includes bibliographical references (leaf 53).by Sewon Park.M.S

Foundation of Computer (Algebra) ANALYSIS Systems: Semantics, Logic, Programming, Verification

We propose a semantics of operating on real numbers that is sound, Turing-complete, and practical. It modifies the intuitive but super-recursive Blum-Shub-Smale model (formalizing Computer ALGEBRA Systems), to coincide in power with the realistic but inconvenient Type-2 Turing machine underlying Computable Analysis: reconciling both as foundation to a Computer ANALYSIS System. Several examples illustrate the elegance of rigorous numerical coding in this framework, formalized as a simple imperative programming language ERC with denotational semantics for REALIZING a real function $f$: arguments $x$ are given as exact real numbers, while values $y=f(x)$ suffice to be returned approximately up to absolute error $2^p$ with respect to an additionally given integer parameter $p\to-\infty$. Real comparison (necessarily) becomes partial, possibly 'returning' the lazy Kleenean value UNKNOWN (subtly different from $\bot$ for classically undefined expressions like 1/0). This asserts closure under composition, and in fact 'Turing-completeness over the reals': All and only functions computable in the sense of Computable Analysis can be realized in ERC. Programs thus operate on a many-sorted structure involving real numbers and integers, the latter connected via the 'error' embedding $Z\ni p\mapsto 2^p\in R$, whose first-order theory is proven decidable and model-complete. This logic serves for formally specifying and formally verifying correctness of ERC programs

Impact of calcium on salivary α-amylase activity, starch paste apparent viscosity and thickness perception

Thickness perception of starch-thickened products during eating has been linked to starch viscosity and salivary amylase activity. Calcium is an essential cofactor for α-amylase and there is anecdotal evidence that adding extra calcium affects amylase activity in processes like mashing of beer. The aims of this paper were to (1) investigate the role of salivary calcium on α-amylase activity and (2) to measure the effect of calcium concentration on apparent viscosity and thickness perception when interacting with salivary α-amylase in starch-based samples. α-Amylase activity in saliva samples from 28 people was assessed using a typical starch pasting cycle (up to 95 °C). The activity of the enzyme (as measured by the change in starch apparent viscosity) was maintained by the presence of calcium, probably by protecting the enzyme from heat denaturation. Enhancement of α-amylase activity by calcium at 37 °C was also observed although to a smaller extent. Sensory analysis showed a general trend of decreased thickness perception in the presence of calcium, but the result was only significant for one pair of samples, suggesting a limited impact of calcium enhanced enzyme activity on perceived thickness