D-value

(noun)

The time needed to reduce the bacterial population by 90% or one log10 at a given temperature.

Related Terms

Examples of D-value in the following topics:

  • Rate of Microbial Death

    • This D-value reference (DR) point is 121°C.
    • Z or z-value is used to determine the time values with different D-values at different temperatures with its equation shown below:
    • This D-value is affected by pH of the product where low pH has faster D values on various foods.
    • The D-value at an unknown temperature can be calculated knowing the D-value at a given temperature provided the Z-value is known.
    • This curve presents the DR value (12.6 seconds) and the 12-D reduction (151 seconds) for C. botulinum.

  • Problems

    • Equate your answer to (a) to the answer to (b) and solve for $dM$.
    • Calculate $dL_\mathrm{surface}/dT$ and $dP_\mathrm{helium}/dT$.
    • Calculate the value of $dM$ for which $dP_\mathrm{helium}/dT$ exceeds $dL_\mathrm{surface}/dT$ and the layer bursts.
    • Equate your value of $dM$ in (c) and (e) and solve for $T$.
    • What is $dM$?

  • Comparing Matched or Paired Samples

    • $t=\dfrac { \bar { { x }_{ d } } -{ \mu }_{ d } }{ \left( \dfrac { { s }_{ d } }{ \sqrt { n } } \right) }$
    • The "before" value is matched to an "after" value, and the differences are calculated.
    • Verify these values.
    • Compare $\alpha$ and the $p$-value: $\alpha = 0.05$ and $p\text{-value} = 0.0095$.
    • $\alpha > p\text{-value}$.

  • B.14 Chapter 12

    • Calculate $dL_\text{surface}/dT$ and $dP_\text{helium}/dT$.
    • Calculate the value of $dM$ for which $dP_\text{helium}/dT$ exceeds $dL_\text{surface}/dT$ and the layer bursts.
    • Equate your value of $dM$ in (c) and (e) and solve for $T$.
    • What is $dM$?
    • $\displaystyle \frac{dP_\text{He}}{dT} = 4.2 \times 10^{10} \text{erg/s/g/K} T_9^{-5} \exp (4.32/T_9) (36 - 25 T_9) dM.$

  • Applications of Multiple Integrals

    • Given a set $D \subseteq R^n$ and an integrable function $f$ over $D$, the average value of $f$ over its domain is given by:
    • where $m(D)$ is the measure of $D$.
    • If there is a continuous function $\rho(x)$ representing the density of the distribution at $x$, so that $dm(x) = \rho (x)d^3x$, where $d^3x$ is the Euclidean volume element, then the gravitational potential is:
    • $\displaystyle{\vec E = \frac {1}{4 \pi \epsilon_0} \iiint \frac {\vec r - \vec r'}{\| \vec r - \vec r' \|^3} \rho (\vec r')\, {d}^3 r'}$

  • Base Rates

    • Let's call this Event D.
    • Or, more formally, P(D) = 0.02.
    • If D' represents the probability that Event D is false, then P(D') = 1 - P(D) = 0.98.
    • To define the diagnostic value of the test, we need to define another event: that you test positive for Disease X.
    • The diagnostic value of the test depends on the probability you will test positive given that you actually have the disease, written as P(T|D), and the probability you test positive given that you do not have the disease, written as P(T|D').

  • Double Integrals Over General Regions

    • the projection of $D$ onto either the $x$-axis or the $y$-axis is bounded by the two values, $a$ and $b$.
    • any line perpendicular to this axis that passes between these two values intersects the domain in an interval whose endpoints are given by the graphs of two functions, $\alpha$ and $\beta$.
    • $x$-axis: If the domain $D$ is normal with respect to the $x$-axis, and $f:D \to R$ is a continuous function, then $\alpha(x)$  and $\beta(x)$ (defined on the interval $[a, b]$) are the two functions that determine $D$.
    • $y$-axis: If $D$ is normal with respect to the $y$-axis and $f:D \to R$ is a continuous function, then $\alpha(y)$ and $\beta(y)$ (defined on the interval $[a, b]$) are the two functions that determine $D$.
    • Calculate $\iint_D (x+y) \, dx \, dy$.

  • Bound-Free Transitions and Milne Relations

    • $\displaystyle \frac{dN}{dA dt} = 4\pi \frac{J_\nu}{\hbar \omega} d\nu = 4\pi \frac{J_\nu}{2\pi \hbar\omega} d\omega$
    • $\displaystyle d\sigma = \frac{8\pi^2}{3 \hbar^2 c} \frac{\hbar\omega}{2 d\omega} | {\bf d}_{if} |^2 \left [ \frac{dn}{dp d\Omega} dp d\Omega \right ] $
    • $\displaystyle \frac{d\sigma}{d\Omega} = \frac{p V m \omega}{6\pi c \hbar^3} |{\bf d}_{if} |^2 .$
    • Had we used the classical dipole operator ${\bf d} = e {\bf r}$ we would have twice the true value of $N_n$ and four times the cross section, so the difference is not subtle.
    • We can improve upon the assumption that we made that the electron's energy is much greater than the ionization energy by using Coulomb wavefunctions which are solutions to the Schrodinger equation for positive (i.e. continuum) energy values.

  • Debt to Equity

    • However, the ratio may also be calculated using market values for both if the company's debt and equity are publicly traded, or using a combination of book value for debt and market value for equity financially. ""
    • The relationship between D/E and D/C is: D/C = D/(D+E) = D/E / (1 + D/E)
    • The debt-to-total assets (D/A) is defined asD/A = total liabilities / total assets = debt / (debt + equity + non-financial liabilities)
    • Both the formulas below are therefore identical: A = D + EE = A – D or D = A – E
    • Debt to equity can also be reformulated in terms of assets or debt: D/E = D /(A – D) = (A – E) / E

  • Summary of the Uniform and Exponential Probability

    • X = a real number between a and b (in some instances, X can take on the values a and b). a = smallest X ; b = largest X
    • Area Between c and d: P(c < X < d) = (base)(height) = (d−c)(height).
    • Area Between c and d: P(c < X < d) = P(X < d)−P(X < c) =1−e−m·d−(1−e−m·c) = e−m·c−e−m·d