Data Analysis

Import created→started→resolved timestamps from CSV (Jira-style or simple) and get flow metrics the way agile coaches read them: lead/cycle time percentiles, WIP age, throughput per day/week/month, a cumulative flow diagram and a Little's Law consistency check.

Math & Numbers

Two-phase simplex for 2–6 variables and 1–8 ≤/≥/= constraints: Bland's rule, per-iteration pivot log, optimal/unbounded/infeasible status, and substitution checks.

Math & Numbers

Table lookup of L{f(t)} for 14 standard pairs, with parameter substitution, region of convergence, derivation note, and optional numeric F(s₀) evaluation.

Education

Convert mAs ↔ µAs/mC/C charge units and compute equivalent-technique mAs after changing kVp (n ≈ 5 power law, 15 % rule).

Education

NEB-style ligation setup: solve mode computes insert_ng = ratio × vector_ng × (insert bp/vector bp); check mode reports the actual pmol ratio. Recommended bands by insert size (5–10:1 under 200 bp, 3–5:1 to 1 kb, 1–5:1 above), concatemer warning above 10:1, and nM concentrations from the reaction volume. NEB / Promega / Sambrook derived. Educational use only.

Education

Compute Wright's r = Σ (1/2)^(n1+n2)(1+F_A) and kinship φ = r/2 for two individuals, with reference values (full sib 0.5, half sib 0.25, first cousins 0.125) and relationship-degree classification. Child F = parental φ. Derived from Wright 1922, Falconer & Mackay, Hartl & Clark 2007, Jacquard 1970. Educational use only.

Education

Paste a bilingual vocabulary list and export an Anki-compatible deck that auto-splits each entry into recognition, recall, and cloze cards with POS, IPA, and example sentences, plus an SM-2 scheduling preview.

Date & Time

IERS leap-second history (27 insertions since 1972), current TAI-UTC offset (+37 s), DUT1 (UT1-UTC) notes, and POSIX/NTP/GPS/TAI/UT1 cross-system conversion for a given UTC instant

Health

Calculate LDL-C (low-density lipoprotein cholesterol) indirectly with the Friedewald formula. In mg/dL: LDL-C = Total Cholesterol − HDL-C − (Triglycerides / 5); in mmol/L: LDL-C = TC − HDL-C − (TG / 2.2). Unreliable when triglycerides ≥ 400 mg/dL (4.5 mmol/L), in the non-fasting state, in type III dysbetalipoproteinemia, and at very low LDL-C (< 70 mg/dL). Treatment thresholds (ACC/AHA 2018): < 70 mg/dL (1.8 mmol/L) high-risk secondary prevention; < 100 mg/dL (2.6 mmol/L) moderate-risk / diabetes primary prevention; ≥ 190 mg/dL (4.9 mmol/L) suggests familial hypercholesterolemia. Unit system selectable: mg/dL or mmol/L. Derived from Friedewald 1972, Martin 2013, Sampson 2020, and ACC/AHA 2018. Not medical advice.

Astronomy

Parse a TLE, show the six Keplerian elements (with derived semi-major axis & period), propagate with SGP4 for ECI position, sub-satellite point, ground track, elevation visibility and Doppler shift

Health

Estimate single-pool Kt/V (spKt/V) for a hemodialysis session with the Daugirdas second-generation formula: Kt/V = −ln(R − 0.008·t) + (4 − 3.5·R) × UF / W, where R = Post-BUN/Pre-BUN, t = treatment time (h), UF = ultrafiltration volume (kg), W = post-dialysis weight (kg). The first term captures urea removal and generation; the second corrects for volume contraction. KDOQI target: spKt/V ≥1.2 per session (minimum delivered dose) for conventional thrice-weekly hemodialysis, target ~1.4. Requires post-dialysis BUN drawn by slow-flow/stop-pump technique. Derived from Daugirdas JT, J Am Soc Nephrol 1993. Valid for intermittent hemodialysis; not for peritoneal dialysis or CRRT/SLED. Not medical advice.

Math & Numbers

Convert kinematic viscosity (ν = dynamic viscosity / density) between m²/s (square metres per second, SI base), cSt (centistokes, 1 cSt = 1e-6 m²/s = 1 mm²/s), and ft²/s (square feet per second, 1 = 0.09290304 m²/s). Converts via m²/s to the target unit and also lists the equivalent value in all three units for reference. Reference values: water 20°C ≈ 1.004 cSt, SAE 30 oil ≈ 300–400 cSt at 40°C.