The phrase "a negative fraction is" is correct and usable in written English.
It can be used in mathematical contexts when discussing fractions that have a negative value.
Example: "In mathematics, a negative fraction is represented with a minus sign, such as -1/2."
Alternatives: "a negative ratio is" or "a negative value fraction is".
Use an aliquot of cells and determine by immunofluorescence if the negative fraction is devoid of fibroblasts.
Model sensitivity true positive fraction is the ratio between correctly classified presence data and all presence data, while model specificity true negative fraction is the ratio between correctly classified grid cells without landslides and all grid cells without landslide (Pradhan and Lee 2010).
In each experiment, a STRO-1 negative fraction was treated accordingly.
The negative fraction was stained with anti-G8.8-FITC (anti-EpCAM, generated from a G8.8 hybridoma cell line), anti-Ly51-PE (BD Biosciences), anti-CD45-PerCP-Cy5.5 (BD Biosciences) and anti-CD80 biotin (BD Biosciences) followed by second-stage staining with Streptavidin-PE-Cy7 (Serotec Ltd).
The negative fraction was allowed to flow through and collected for further analysis.
Genes that are specifically transcribed in the GFP positive fraction (absent in GFP negative fraction) are represented in Additional file 3 Table S4, again as common to somites and limbs (A), somite specific sequences (B) and limb specific sequences (C).
FACS analysis immediately before the multi-lineage assay showed that approximately 40% of the cells in the positive fraction were still CD166+ and only approximately 2% of the cells in the negative fraction were CD166+.
The negative fraction was incubated with mouse anti-rat Thy1.1 antibody (1 125; BD Pharmingen, San Diego, CA), followed by secondary rat anti-mouse IgG1 antibody conjugated to magnetic beads (Miltenyi Biotec).
The negative fractions were the cells that were negative for either CD36/glycophorin A or CD71/glycophorin A or were the CD45+ cells.
Cells were purified over pre-cooled MS-separation columns (Miltenyi Biotec); the positive and negative fractions were collected and each was passed over an additional separation column in order to optimize purity.
