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The 300-Year Unbreakable Cipher That Got Broken — Vigenère, Enigma, and What Every "Unbreakable" Cipher Has in Common
Base64 vs Base64url: Why `+`, `/`, and `=` Break URLs, and Why JWTs Use a Different Alphabet
Standard Base64's `+`, `/`, and `=` characters all have special meaning in URLs — which is why a Base64-encoded JWT pasted directly into a URL can silently corrupt, and why Base64url exists as a separate, URL-safe alphabet. Here's exactly which characters differ, why JWTs require Base64url specifically, how padding works and why Base64url commonly omits it, and how to tell the two variants apart.
Ketogenic Diets and Nutritional Ketosis: What the Research Shows About Weight Loss, Performance, and Who Should Be Cautious
Ketogenic diets shift the body's fuel source from glucose to fat and ketones — a measurable metabolic state with the strongest evidence base in drug-resistant epilepsy. Here's how nutritional ketosis differs from dangerous diabetic ketoacidosis, what weight loss research actually shows over longer timeframes, and the mixed evidence on athletic performance.
Harris-Benedict vs Mifflin-St Jeor vs Katch-McArdle: Why BMR Formulas Disagree by 100-200 Calories
BMR calculators don't all use the same formula — Harris-Benedict (1919, revised 1984), Mifflin-St Jeor (1990), and Katch-McArdle (lean-mass-based) can disagree by 100-200 calories for the same person, which represents 20-30% of a typical weight-loss deficit. Here's how each formula was developed, why they diverge more for people at the extremes of body composition, and why any formula's output should be treated as a starting point rather than a precise target.
JSON Patch and JSON Pointer: How "What Changed" Becomes a Standardized, Executable Sequence of Operations
"What's different between these two JSON documents" and "what's the smallest sequence of operations that transforms one into the other" are related but distinct questions — the second is what JSON Patch (RFC 6902) standardizes. Here's the six JSON Patch operations, the JSON Pointer path syntax they rely on, how the test operation enables optimistic concurrency control, and when the simpler JSON Merge Patch is sufficient instead.
BMI and Pregnancy: Why Pre-Pregnancy BMI Matters and "Current BMI" During Pregnancy Doesn't Mean What You'd Think
A pregnant person's BMI increases throughout pregnancy simply because of the pregnancy itself — applying standard BMI categories to this changing number would be meaningless. Here's why clinical weight-gain guidance uses pre-pregnancy BMI as a fixed reference point instead, why "total weight gain from that reference point" is the relevant question rather than "current BMI category," and how postpartum BMI takes time to become meaningful again.
BMI and Ethnicity: Why the WHO Recommends Lower Thresholds for Asian Populations
A BMI of 24 is "normal" by standard categories but already represents "increased risk" under WHO's Asian-specific BMI cut-offs (23 for overweight, 27.5 for obese). Here's why these adjustments exist, the body composition research behind them, UK NICE guidance for multiple ethnic groups, and why waist circumference complements BMI across populations.
Combat Sport Weight Classes, Weight Cutting, and Why Losing 10kg Overnight Is Dangerous
MMA fighters sometimes lose 10+ kg between weigh-in and competition through dehydration — competing at weights 10–15% above their weight class. Here's how combat sport weight classes work, the physiology and risks of extreme weight cutting, regulatory responses, and how powerlifting handles weight classes differently.
EPOC, the "Afterburn Effect," and HIIT vs Steady-State: Separating Research from Marketing
EPOC ("afterburn") adds approximately 6-15% to a workout's calorie burn — real, but smaller than fitness marketing implies. Here's what EPOC actually measures, why HIIT's real advantage is time efficiency rather than metabolic magic, how HIIT and steady-state compare for fat loss, and how resistance training's EPOC differs from cardio's.
Animal Speeds and the Physics of Locomotion: Why Cheetahs Tire in 30 Seconds and Humans Are Elite Endurance Runners
A cheetah can't outsprint a horse over a mile, and a peregrine falcon at 320 km/h is faster than both but only in a gravity-assisted dive. Here's why cheetahs tire after 30 seconds, how the pronghorn evolved to outrun extinct North American cheetahs, and why humans are actually elite endurance animals.
Step-Up SIP: Why a 10% Annual Increase in Contributions Does Far More Than "10% More Savings"
Increasing your SIP by 10% annually — roughly matching a typical raise — can shrink the time to reach a savings goal by years, not months, because the step-up compounds on top of investment returns that are already compounding. Here's the "two compounding effects" framing, how to choose a step-up rate aligned with realistic income growth, and why automating the step-up removes a recurring decision point that's easy to defer.
JWT Token Refresh Strategies: Access Tokens, Refresh Rotation, and When Sessions Beat JWTs
Short-lived access tokens require a refresh mechanism — and how you implement that mechanism determines your app's security and user experience. Here's refresh token rotation, silent refresh in SPAs, theft detection via refresh token families, and the cases where server-side sessions are simpler and safer.
Hypermiling Techniques: The Driving Habits That Measurably Improve Fuel Economy
Driving at 70 mph instead of 80 mph cuts fuel consumption by approximately 25% on the motorway. Here's the aerodynamics behind that, plus tyre pressure, anticipatory braking, route planning, and the other hypermiling techniques with measurable impact.
