One Step Rise Onset

Locate the first sampled titer rise meeting a supplied fold threshold; resolution is bounded by sampling, not continuous onset inference.

Description

Find the first sampled titer meeting a supplied rise threshold and report its preceding sample time without interpolating onset.

A one-step growth experiment follows virus production after a defined infection period. The rise in measured infectious titer and the eventual yield describe different features of the experiment. Sampling records the titer at discrete times, so an observed rise does not reveal its exact continuous onset.^[1]

This tool defines a rise by multiplying a supplied positive baseline titer by a minimum fold increase greater than one. It scans a chronological time series for the first sampled value at or above that threshold.

One Step Rise Onset returns the first qualifying sample time, a detection flag, and the preceding sample time when available. The value −1 is a missing-result sentinel rather than an experimental hour.

When to locate a sampled rise above baseline

Use the tool for an already measured titer time series with strictly increasing nonnegative observation hours. Select the baseline and fold criterion from the experimental analysis rather than treating the calculator as a growth-curve fit.

Locate the first sampled value reaching a defined rise threshold.
Retain the preceding sample time as sampling context.
Distinguish no qualifying sample from a rise already present at the first observation.

How to enter time samples and locate the first threshold crossing

Enter Observation hours in strictly increasing order and aligned nonnegative Titers in the same assay units.
Enter positive Baseline titer and Minimum rise fold greater than 1.
Run the tool and inspect Detected before interpreting the two time outputs.
If detected, use First rise hour as the first qualifying observation and Last below rise hour as its preceding observation when available.

threshold = baselineTiter×minimumRiseFold; index = first i with titers_i ≥ threshold

The implementation uses an inclusive comparison and stops at the first qualifying sample. Titers need not increase monotonically.

Observation pattern	Time outputs
A qualifying sample has a preceding observation	firstRiseHour is its time; lastBelowRiseHour is the preceding time.
The first sample already qualifies	firstRiseHour is the first time; lastBelowRiseHour is −1.
No sample qualifies	Both time outputs are −1 and detected is false.

json

{
  "input": {
    "observationHours": [
      0,
      1,
      2,
      3
    ],
    "titers": [
      10,
      10,
      20,
      50
    ],
    "baselineTiter": 10,
    "minimumRiseFold": 2
  },
  "output": {
    "firstRiseHour": 2,
    "detected": true,
    "lastBelowRiseHour": 1
  }
}

Later declines do not undo an earlier qualifying observation. Empty or misaligned lists, repeated/unordered hours, negative values, a nonpositive baseline, and a fold criterion at most one produce input errors.

Limitations of sampled rise timing

No interpolation, smoothing, fit, uncertainty interval, or exact biological onset is inferred.
The preceding time supplies sampling context, not proof that no unobserved rise occurred earlier.
If no rise is detected, lastBelowRiseHour is also −1 even though below-threshold samples were submitted.
The tool does not verify single-cycle infection, adsorption completion, baseline validity, or assay quality.

Alternative or Complementary growth timing and yield summaries

Use a separate timeline summary when adsorption, intracellular detection, and extracellular detection events have already been identified. Use plateau and baseline measurements to estimate infectious progeny per infected cell independently of rise timing.

References

The Growth of Bacteriophage — Journal of General Physiology; E. L. Ellis and M. Delbrück (1939)

Similar or alternative tools

Eclipse Latent Period Timeline
Summarize supplied experimental event times for intracellular and extracellular detection.
One Step Burst Yield
Calculate background-subtracted infectious yield per infected cell from plateau and baseline titers.