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  2. Mass spectrum - Wikipedia

    en.wikipedia.org/wiki/Mass_spectrum

    A mass spectrum is a histogram plot of intensity vs. mass-to-charge ratio (m/z) in a chemical sample, [1] usually acquired using an instrument called a mass spectrometer. Not all mass spectra of a given substance are the same; for example, some mass spectrometers break the analyte molecules into fragments ; others observe the intact molecular ...

  3. Histogram - Wikipedia

    en.wikipedia.org/wiki/Histogram

    This histogram shows the number of cases per unit interval as the height of each block, so that the area of each block is equal to the number of people in the survey who fall into its category. The area under the curve represents the total number of cases (124 million). This type of histogram shows absolute numbers, with Q in thousands.

  4. List of unsolved problems in chemistry - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    Protein folding problem: Is it possible to predict the secondary, tertiary and quaternary structure of a polypeptide sequence based solely on the sequence and environmental information? Inverse protein-folding problem: Is it possible to design a polypeptide sequence which will adopt a given structure under certain environmental conditions?

  5. List of probability distributions - Wikipedia

    en.wikipedia.org/wiki/List_of_probability...

    The Behrens–Fisher distribution, which arises in the Behrens–Fisher problem. The Cauchy distribution , an example of a distribution which does not have an expected value or a variance . In physics it is usually called a Lorentzian profile , and is associated with many processes, including resonance energy distribution, impact and natural ...

  6. Dose-volume histogram - Wikipedia

    en.wikipedia.org/wiki/Dose-volume_histogram

    The lines always slope and start from top-left to bottom-right. For a structure receiving a very homogeneous dose (100% of the volume receiving exactly 10 Gy, for example) the cumulative DVH will appear as a horizontal line at the top of the graph, at 100% volume as plotted vertically, with a vertical drop at 10 Gy on the horizontal axis.

  7. V-optimal histograms - Wikipedia

    en.wikipedia.org/wiki/V-optimal_histograms

    V-optimal histograms are an example of a more "exotic" histogram. V-optimality is a Partition Rule which states that the bucket boundaries are to be placed as to minimize the cumulative weighted variance of the buckets. Implementation of this rule is a complex problem and construction of these histograms is also a complex process.

  8. Entropy estimation - Wikipedia

    en.wikipedia.org/wiki/Entropy_estimation

    A new approach to the problem of entropy evaluation is to compare the expected entropy of a sample of random sequence with the calculated entropy of the sample. The method gives very accurate results, but it is limited to calculations of random sequences modeled as Markov chains of the first order with small values of bias and correlations ...

  9. Histogram matching - Wikipedia

    en.wikipedia.org/wiki/Histogram_matching

    An example of histogram matching In image processing , histogram matching or histogram specification is the transformation of an image so that its histogram matches a specified histogram. [ 1 ] The well-known histogram equalization method is a special case in which the specified histogram is uniformly distributed .