Hand-considered hypotheses, 901–1000

Written one at a time, not composed. The subject is apparatus: sensors worn on and placed in the body, the physics of medical images, sterilisation as a transport problem, and the hardware of clinical measurement. Each entry carries the form of its argument rather than a topic tag — a quantity misattributed, a bound, an inversion, a count, a degeneracy, an artefact wearing the costume of an effect. Physical mechanisms only: no entry claims anything about diagnosis, treatment or efficacy, and none is medical advice. Nothing here has been measured; where a number appears it is an order-of-magnitude estimate and is marked as one. None has been tested.

Sensors on the body

Misattribution
H901. Slow baseline wander in a wrist photoplethysmogram is routinely blamed on vasomotion, but a large share of it is the hydrostatic column between wrist and heart changing with arm posture. Tilting a subject at fixed metabolic state separates the two, since the vasomotor component persists at constant gravitational potential while the hydrostatic term follows the cosine of the tilt.
Hidden term
H902. Chloride activity at the skin surface writes itself into every biopotential as a drifting half-cell potential, and no input impedance removes it because it is a real source rather than a loading error. Two electrolytes of different chloride activity on adjacent sites should decay with different time constants, which lets the biological term be subtracted by its kinetics alone.
Identity
H903. Motion artefact at a dry electrode and skin-stretch artefact at a strain gauge are one triboelectric charge redistribution seen through two couplings, which is why a wearable cannot be immune to the first and sensitive to the second. Pressing both sensors against a rigid window at matched strain should collapse their signatures into a single waveform.
Bound
H904. Power an inductive link can deliver through tissue is capped by coil quality factor and by eddy-current loss in the medium, and the cap is set by conductivity at the carrier frequency rather than by geometry. Sweeping a saline phantom's conductivity across the physiological range should move the optimum frequency in a direction predictable from the loss tangent, with the coil untouched.
Threshold
H905. Cavitation in coupling gel begins at a negative pressure fixed by the size distribution of undissolved gas nuclei, which is why two gels of identical acoustic impedance can give different measured output. Degassing one aliquot under vacuum while leaving its twin at ambient should shift the inception threshold by a ratio set by the nuclei's Laplace pressure.
Reversal
H906. Contact pressure on a dry electrode first lowers impedance and then raises noise, because beyond a point the pressure expresses interstitial fluid from the stratum corneum and the contact turns capacitive. A pressure sweep with simultaneous impedance and noise spectra puts the crossover at a pressure that should scale with skin hydration.
Count
H907. Multi-frequency bioimpedance returns at most as many independent tissue parameters as the band contains distinct relaxations, so a fit with more parameters than processes is trading them against one another. A two-component phantom of known geometry should yield exactly two, and any model that returns three is fitting its own electrode term.
Artefact mimicking effect
H908. Heart-rate variability taken from a low-rate wrist photoplethysmogram can be the peak detector's sampling jitter rather than any rhythm of the body, appearing as broadband variability with a floor at the sample interval. Interpolating the same record tenfold should leave genuine variability intact and erase the floor, which is the discriminating check.
Scale argument
H909. A microneedle shorter than the stratum corneum cannot reach living epidermis however sharp its tip, so length and sharpness are not interchangeable design variables. Arrays of identical tip radius and stepped length, pressed at equal force, should show a sharp drop in contact impedance at the corneum's thickness.
Inversion of standard practice
H910. Textbook practice puts a conductive ground plane behind a body-worn antenna to cut absorbed power, yet at frequencies where the plane spans a fraction of a wavelength it can concentrate the near field at the feed. Measuring peak local field with and without the plane at fixed radiated power locates the crossover thickness, which should scale with wavelength in tissue.
Selection effect
H911. Reliability figures for implanted sensors come only from units that survived sterilisation and handling, so the reported failure rate is conditional on passing the step most likely to damage the encapsulation. Sacrificial test structures measured after sterilisation but never implanted should expose the early failures the conditional sample hides.
Unit trap
H912. Attenuation written as dB per centimetre per megahertz is a different quantity from attenuation in dB per centimetre at a stated frequency, and comparing them without the frequency factor manufactures a discrepancy. Recomputing two phantom datasets to a common reference frequency should abolish the apparent disagreement without changing either measurement.
Derived quantity
H913. Pulse-wave velocity is treated as measured and stiffness as derived, yet a wearable actually times a pulse between two optical sites, so both quantities inherit an assumed path length. A two-distance measurement on the same subject constrains that path length and shows which quantity the data really fixes.
Degeneracy
H914. Fitting T2 and proton density together from a short-spaced multi-echo train makes the pair nearly degenerate, so a reported T2 change can be a density change absorbed into the fit. Fixing density from an independent sequence and refitting should move T2 only where the degeneracy was real.
Non-identifiability
H915. Impedance spectra of a skin contact cannot separate the electrode's double-layer capacitance from the skin's dispersion when the two relaxation times sit within a decade. A series of skin-mimicking membranes of known properties reproduces the spectra without ambiguity and is the only way to assign the terms.

Implants and interfaces

Hidden term
H916. Helium leak testing certifies the seal and, silently, the polymer's own permeability, so a package can pass while water vapour crosses the encapsulation at a rate the tracer never sees. A second run with a heavier tracer gas separates seal leakage from bulk permeation by their different diffusion coefficients.
Identity
H917. Corrosion at an implanted electrode and the impedance rise attributed to it are one interfacial process read chemically and electrically, so a stable impedance does not prove an intact surface — area loss can be offset by roughening. Explanted electrodes with matched impedance histories, profiled for real area, should show where the two measures part.
Bound
H918. Charge a stimulating electrode can inject is bounded by the reversible charge density of its own surface, and waveform shape only decides how much of that bound is used before the potential crosses the water window. Sweeping waveform at fixed total charge while monitoring electrode potential against a reference should converge on a common intercept.
Threshold
H919. Beneath a certain tissue thickness an implanted antenna cannot radiate efficiently at all, because the near field is dominated by the lossy medium rather than by radiation; the thickness is on the order of a tenth of a wavelength in tissue (an estimate). Antennas of decreasing size at fixed frequency, measured in a body phantom, should lose efficiency at the same thickness regardless of design.
Reversal
H920. Thickening an encapsulation layer past a point speeds water ingress rather than slowing it, since the thicker layer holds a larger equilibrium concentration and feeds the interface for longer. Laminates of equal total thickness in different layer order should differ in the lag time before interior humidity begins to rise.
Count
H921. Four error coefficients bound a bridge-type implanted sensor — offset, span, and two cross-sensitivities — and every further coefficient in a datasheet is a combination of these. A full factorial calibration over temperature and pressure should return a residual matrix of rank four.
Artefact mimicking effect
H922. The fouling resistance of a zwitterionic implant coating, measured in a static dish, is often the absence of the shear that would have deposited protein rather than a thermodynamic barrier. A parallel-plate flow cell spanning two decades of wall shear should bring coated and uncoated surfaces together once shear is high enough.
Scale argument
H923. At the scale of one cell, an electrode's double-layer charging time exceeds the ionic transient it is meant to record, so a microelectrode returns a filtered copy whose constant is set by area. Electrodes of one material and different area should produce transients of different width but identical onset.
Inversion of standard practice
H924. Sealing a feedthrough with the highest available dielectric strength is standard, yet a lower-permittivity feedthrough can be better because it couples less common-mode body potential into the circuit. Equal geometries of different permittivity, tested with an injected common-mode signal, should show the inversion and locate the trade between breakdown and displacement current.
Conservation budget
H925. Loss in an inductive link does not vanish at the coil terminals: most of it lands in tissue within a few centimetres, so terminal efficiency overstates what the medium tolerates. Calorimetry on a phantom at matched terminal efficiency, with coil position varied, should make the discrepancy appear as a position dependence.
Hidden variable
H926. Scatter in impedance between nominally identical implanted electrodes is dominated by how much geometric area the encapsulation actually left exposed, not by the metal, and that area varies with the moulding step. Optical area measurement on the same units before implantation should absorb most of the scatter.
Symmetry argument
H927. Exchanging the two electrodes of a bipolar pair must invert the signal and leave the noise unchanged, so any residual difference belongs to the amplifier or the tissue, never to the source. Recording both polarities and averaging cancels everything source-independent and leaves the asymmetry as a measurable residue.
Threshold
H928. Below some contact area, an electrode's own thermal noise exceeds the amplifier's at every usable bandwidth, so selectivity bought by shrinking the electrode costs signal-to-noise that no front end recovers. An area series measured through one amplifier should show where total noise stops falling.
Degeneracy
H929. Received power in a wireless implant depends on coil misalignment and on tissue conductivity almost degenerately at a single frequency, so telemetry strength cannot stand in for coupling. Two frequencies with different penetration should break the degeneracy and let one be held while the other is inferred.
Counterexample
H930. A passive implant can resonate at the scanner's frequency without any long conductor, since the electrolyte path through tissue and the package's own capacitance close the loop. A pair of short plates a few centimetres apart that heats in a phantom is the constructive counterexample, and comparing implants with and without such pairs separates loop heating from dielectric heating.

Imaging physics

Misattribution
H931. Beam-hardening streaks are blamed on the polychromatic source, but a small object shows the same streaks under a monochromatic beam when the detector's gain depends on energy. A monochromatic scan with the gain curve measured and flattened should leave the streaks in place if the detector is the cause.
Hidden term
H932. Each CT number carries a term from the reconstruction kernel acting on nearby edges, so a material's value depends on what surrounds it. Scanning one insert inside two phantoms of different surrounding contrast separates the material term from the kernel term.
Identity
H933. Partial-volume averaging and motion blur are one convolution seen along different axes, which is why a single blurred image cannot tell a small object from a moving sharp one. A gated acquisition at the same total exposure keeps the motion term and removes the partial-volume term.
Bound
H934. Resolution in a projection image is bounded by the detector aperture, not the focal spot, once magnification passes the ratio of the two, and no source shrinking helps beyond that point. A magnification series at fixed detector should show the plateau arriving at a predictable value.
Threshold
H935. Edge enhancement by propagation appears only beyond a distance set by the object's gradient length, so a faint sharp edge can vanish at one distance and dominate at another with identical absorption. A distance series on a step phantom locates the threshold as a function of edge sharpness rather than of contrast.
Reversal
H936. Raising field strength improves MRI signal-to-noise only until body-dominated noise grows faster than signal, at which point the trend reverses. Coil-loading measurements at two field strengths with one coil geometry should show the reversal as a change in which noise source dominates.
Count
H937. N coil elements support at most N-fold acceleration without extra encoding, and a reconstruction claiming more is leaning on the object's own sparsity, which white-noise texture does not have. A noise-textured phantom should show the limit as an abrupt onset of artefact at a predictable factor.
Artefact mimicking effect
H938. Apparent focal enhancement in a subtraction image is frequently sub-voxel misregistration between the two acquisitions, and it grows with the background gradient rather than with the contrast agent. A saline injection on the same timing schedule should reproduce the pattern if misregistration is the mechanism.
Scale argument
H939. For an object smaller than the reconstruction voxel, the reconstructed peak scales with volume rather than attenuation, so a small dense object and a larger faint one become indistinguishable at one voxel size. Halving the voxel size on the same data should separate them if volume scaling is the cause.
Inversion of standard practice
H940. Higher tube voltage is the standard way to penetrate a thick part, but for a faint feature inside a thin dense shell, lowering it can raise contrast-to-noise because the photoelectric term grows faster than total attenuation. A voltage series at matched detector signal should put the optimum below the highest tube setting.
Selection effect
H941. Uniformity and noise figures come from phantoms chosen to fit the field of view and to be homogeneous, so they exclude the edge conditions that dominate a body-sized object. The same measurements on an oversized phantom should shift the numbers in the direction the beam-hardening correction dictates.
Unit trap
H942. Intensity in mW/cm² and mechanical index are not interchangeable measures of exposure: one is a spatial average and the other a peak rarefactional pressure, and they differ by the beam's peak-to-average ratio. A single beam-profile scan lets both be computed from one dataset and shows the ratio explicitly.
Derived quantity
H943. An apparent diffusion coefficient is a ratio of two signals, so its noise inherits both terms correlated through the same coil sensitivity, and the variance is not what a single exponential fit predicts. Acquiring the same voxel with reversed b-value order should expose the correlation as a change in fitted variance.
Threshold
H944. There is a scatter thickness below which a Compton correction subtracts more variance than scatter, because the correction is estimated from the same quantum-limited data. A thickness series at matched exposure, correction on and off, locates the crossover.
Degeneracy
H945. Dual-energy material decomposition becomes degenerate wherever the two attenuation curves run parallel, which for most soft materials happens near the high-energy end, and noise is amplified exactly there. Choosing basis pairs that cross at the operating energies should move the degenerate region with the spectrum.
Aliasing
H946. When the gantry is sampled near a multiple of its rotation frequency, high-frequency wobble folds into a low-frequency ring and then reads as a mechanical fault at the wrong frequency. Recording the encoder directly and comparing spectra isolates the folded term from the true one.
Boundary condition
H947. The acoustic boundary assumed at a transducer face — rigid or pressure-release — changes the predicted focal field by more than manufacturing tolerance does, so a field measurement cannot validate a design that leaves it unstated. Backing one transducer with two different impedances separates the boundary term from the design term.
Conservation budget
H948. Absorbed optical energy in a vessel splits between acoustic emission and heat according to pulse duration relative to stress confinement, and ignoring the split makes recovered absorption depend on the pulse. Imaging one absorber at a confined and an unconfined duration should give two values that converge once corrected.

Sterilisation physics

Misattribution
H949. Steam failing at the centre of a dense load is blamed on time, but often a trapped air pocket lowers the steam temperature at the same total pressure by a fixed offset. Thermocouples at several depths plus a pressure gauge should show the deficit tracking the air fraction rather than the exposure time.
Hidden term
H950. Biological indicators integrate their carrier's thermal lag, so a stated survival time at a nominal temperature hides the heating and cooling ramps. Identical indicators run at different ramp rates to the same plateau should differ in surviving count even when plateau time is equal.
Identity
H951. Dry-heat kill and steam kill of one organism are the same protein denaturation at different water activity, so dry-heat resistance should follow from steam resistance plus the sorption isotherm. One strain tested at three controlled water activities should collapse both curves onto a single one.
Bound
H952. Ultraviolet kill on a surface is bounded by roughness shadowing rather than lamp output, so a rough surface cannot be sterilised at any dose without a line-of-sight argument. Roughness-matched coupons dosed identically should show the bound as a plateau in surviving count.
Threshold
H953. Ethylene oxide reaching the centre of a wrapped pack has a threshold in the wrap's tortuosity, beyond which the gas cannot arrive within the exposure regardless of concentration. Wraps of equal porosity and different tortuosity should switch behaviour at the same exposure time.
Reversal
H954. More concentrated hydrogen peroxide vapour can lower kill at a fixed cycle time, because the excess condenses on the load and the liquid film blocks vapour from the surface beneath. A load-mass series at fixed concentration should show the reversal at the condensation onset, visible as a mass gain.
Count
H955. Four physical variables govern a sterilisation cycle — temperature, water activity, agent concentration and time — so a validation matrix varying more is measuring combinations rather than new factors. A two-level fractional factorial should show rank four, not more.
Artefact mimicking effect
H956. Failure that reproduces only when the organism sits in its carrier, and not when it is applied directly to the load, is a carrier effect rather than a process effect. Running both placements through one cycle settles which is which without changing the cycle.
Scale argument
H957. Inside a lumen narrower than the sterilant's mean free path at process pressure, transport is Knudsen, so filling time scales with length rather than with the square root of time. A lumen-length series at fixed diameter should show linear ingress.
Inversion of standard practice
H958. Extending exposure is the reflex response to a failing load, but when the failure comes from condensate pooling, a longer exposure adds condensate and deepens the failure. Equal exposure with a longer drying phase should succeed where the longer exposure did not.
Hidden variable
H959. Measured D-values depend on how aggregated the spore population is on its carrier, since an aggregate shields its interior, and aggregation follows the drying method. Suspensions dried two ways to equal viable count should yield two D-values.
Existence claim
H960. A package can be sterile within and contaminated on its own outer surface after a validated cycle, because the process sterilises only what it reaches and the exterior is part of the load. Spore strips placed inside and wrapped outside a test pack, run in one cycle, demonstrate the distinction rather than an anomaly.
Threshold
H961. Electron-beam sterilisation has a depth threshold at the electrons' range, past which energy deposition per unit mass falls to nearly nothing, and no beam current moves that threshold. Thin dosimeters stacked through a package should map the range and show it unchanged when current doubles.
Artefact mimicking effect
H962. Colour change on a chemical indicator is often read as proof the agent arrived, though heat alone can bleach the same dye. Running an indicator through a cycle with the agent withheld is the control that separates the two.

Clinical measurement hardware

Misattribution
H963. An oscillometric cuff does not measure pressure directly; it records the amplitude of its own pressure oscillations and derives systolic and diastolic from an assumed envelope shape. A cuff of different compliance but identical bladder geometry should shift the estimate while the true pressure is unchanged.
Hidden term
H964. Every automated cuff reading contains a hydrostatic offset between cuff and heart that is a fixed pressure term for a given posture, not a calibration error. Readings at two cuff heights on one arm should differ by exactly the fluid column between them.
Identity
H965. Overshoot and hysteresis in an aneroid gauge are one elastic process in the Bourdon tube seen on rising and on falling pressure, so a gauge cannot have one and not the other. Cycling at two rates should collapse both branches onto one curve if the mechanism is shared.
Bound
H966. Accuracy of a differential pressure measurement across a constriction is bounded by the tap's own flow disturbance rather than by the transducer, once the tap's bore exceeds a fraction of the lumen. Taps of decreasing bore in one flow rig should show a plateau where the transducer's specification no longer limits anything.
Threshold
H967. A thermistor's step response has a threshold in medium velocity below which stem conduction, not the boundary layer, sets the dominant time constant. A velocity series in a water bath with identical steps should show the constant switching regimes.
Reversal
H968. Extra mass on a temperature probe quiets its noise and slows it, but past a point the added mass couples more of the ambient through the stem and net drift rises again. Graded-mass probes in one bath, stepped while ambient is held, should show a minimum.
Count
H969. Two parameters at most — slope and offset in the ratio-of-ratios — describe a pulse oximeter's calibration, so a third coefficient is fitting the reference device's nonlinearity. Calibrating across a wide range against two independent reference methods should return residuals consistent with two parameters.
Artefact mimicking effect
H970. A damped-looking arterial waveform is often the fluid-filled tubing resonating below the harmonics it must carry, which removes the dicrotic notch without any change at the source. A tubing-length series at fixed transducer should make the notch disappear and return at predictable lengths.
Unit trap
H971. Defibrillator energy in joules and charge in coulombs are linked by the waveform's voltage, so a fixed-energy setting delivers different charge into a 25-ohm load than into a 50-ohm one (nominal test loads). A load-resistor sweep with voltage and current logged makes the difference explicit.
Derived quantity
H972. End-tidal CO2 is derived from a capnogram peak that has already been filtered and delayed, so its height depends on sampling flow and cuvette response as much as on the gas. Two sampling flows on one breath should give two peaks whose difference is the filter's contribution.
Scale argument
H973. Tubing compliance stores volume that is released after a pump stops, so the bolus on restart scales with compliance and occlusion pressure rather than with programmed volume. Lines of equal length and different compliance, pressurised identically, should deliver different restart boluses.
Inversion of standard practice
H974. Stiffening an infusion line is taught as improving dosing accuracy, yet a stiffer line transmits pump pulsations more faithfully and can raise the peak rate, so volume accuracy and timing accuracy trade against each other. A compliance series with a fast pressure sensor at the patient end should show pulsation amplitude rising as compliance falls.
Selection effect
H975. Published accuracy for wearable thermometer patches is computed from patches that stayed adhered for the whole wear period, which excludes exactly the cases where thermal contact failed. Retaining and measuring every patch, detached ones included, should widen and shift the reported distribution.
Hidden variable
H976. Two ear thermometers disagreeing on one subject differ mostly by field of view and canal geometry, not by detector, so devices sharing a detector but not optics should disagree more than devices sharing optics but not detectors. A variable-aperture blackbody on an optical bench should reproduce the ordering.
Bound
H977. Cuff-based measurement has a temporal resolution bounded by inflation and deflation, so a device reporting beat-to-beat pressures from a cuff is interpolating. Two readings requested a second apart should be more correlated than any physiological signal allows.
Threshold
H978. Current divides between two return electrodes in proportion to contact area, and above a threshold ratio one pad carries nearly all of it regardless of generator setting. A split-pad rig with a current probe on each path should show the transition as the ratio is swept.

Instrument logic across the bench

Misattribution
H979. One electrode gel outperforming another on signal quality is usually a difference in water activity, and thus in how fast it hydrates dry skin, rather than in conductivity. Applying both gels to pre-hydrated and to dry sites should reverse the ranking if hydration is the mechanism.
Hidden term
H980. One-end shield termination puts the shield's potential difference in series with the signal, and that appears as a slow drift across a working day. Terminating the shield at both ends, or at neither, should change the drift while leaving the electrode untouched.
Identity
H981. A ground loop and a common-mode rejection failure are one potential difference described at the source and at the amplifier, so lifting the ground converts the second into a safety question instead of removing it. A differential probe across the two grounds should show the same waveform as the interference.
Count
H982. Any linear two-port used as a sensor has at most three independent calibration constants at one frequency, and a fourth can always be absorbed by moving the reference plane. Shifting the reference plane by a known length in a coaxial jig should leave residuals unchanged if the model is complete.
Bound
H983. Long-term stability of a radiometric measurement is bounded by its reference source rather than its detector, so a better detector cannot rescue a worse reference. Swapping two references of different stability between two detectors should make stability follow the reference.
Reversal
H984. Averaging reduces noise until instrument drift dominates, after which more averaging moves the mean further from the truth; the optimum sits where the two contributions are equal and is usually smaller than the number taken. A long record split into blocks of increasing length shows the optimum as a minimum in the scatter of block means.
Aliasing
H985. A monitor refreshing near a harmonic of the signal it displays produces a beat that exists in neither the body nor the device, and changing the refresh rate alone moves it. Recording raw samples and the displayed image together separates the two.
Saturation
H986. Saturation from a baseline offset compresses a trace rather than clipping it, so small signals still pass, at reduced gain, and read as a smaller true signal. Injecting a known small test tone and watching whether its amplitude tracks the offset exposes the compression.
Closure failure
H987. Closing a calibration chain at the maker's site and opening it at the user's leaves drift acquired in transit undetectable, and a certificate claiming otherwise asserts a property nobody measured. Shipping a transfer standard alongside and measuring it before and after shows whether the chain closes.
Confounding
H988. Cooling a detector to cut dark current also shifts its spectral response, so two detectors compared at different temperatures are two different instruments and their difference is not all noise. Equilibrating both to one temperature should reduce the difference to manufacturing tolerance.
Threshold
H989. Under a few quantisation steps a digitizer biases a lock-in output rather than merely noising it, because the reference phase is estimated from the same coarse samples; the level is an estimate, not a specification. Attenuating a known signal into that region should produce a bias that reverses with reference phase.
Conservation budget
H990. Heat a wearable's electronics produce has to leave somewhere, and the power budget sets a floor on thermal output, so a device claiming long runtime and active cooling is claiming a budget that does not close. Calorimetry in still air should show dissipation matching battery drain within conversion losses.

Calibration and metrology

Misattribution
H991. Traceability is described as a property of a certificate, but it is a property of an unbroken comparison, so a chain that passed through a laboratory which changed hands mid-chain is traceable in neither sense. Auditing comparison records rather than documents is what tests it.
Hidden term
H992. Calibration at one temperature silently carries a coefficient for the temperature at which it is valid, so a device calibrated at 20 °C and used at 30 °C is calibrated at neither; the drift between them is an estimate of the missing term. Calibrating at three temperatures and fitting one coefficient should reproduce what had been called random drift.
Bound
H993. The smallest resolvable change of a sensor is bounded by the stability of its excitation whenever that excitation is common to the measurement path. Two excitations of different stability driving one sensor should show resolution following the excitation, not the noise floor.
Identity
H994. Zero drift and span drift are one physical process seen at two points of the transfer curve, so a device cannot have a stable zero and an unstable span. Measuring at two known inputs over time should show both terms moving in a fixed ratio.
Scale argument
H995. At very short measurement intervals, the dominant error in a differential measurement is timing skew between channels, and its effect scales with slew rate rather than amplitude. A constant-amplitude sine sweep should show error peaking where slew rate peaks, not where the signal does.
Inversion of standard practice
H996. Discarding outlying calibration points is taught as good practice, but when the outliers are the only points at the range's ends they carry all the leverage, and removing them improves the fit while worsening the extrapolation. Fitting with and without the endpoints, then checking an independent standard at the range edge, shows which fit is constrained.
Count
H997. With as many standards as fitted coefficients, a calibration has no degrees of freedom left, and its zero residuals are a construction rather than an agreement. Printing the residual pattern shows it to be identically zero.
Artefact mimicking effect
H998. Interference at a fixed frequency is often the instrument's own clock divided down, which is why it survives shielding: it is generated inside the box. Retuning the clock slightly should move the artefact with it and leave any external source where it was.
Threshold
H999. At low measurement bandwidth a sensor's thermal time constant filters its noise as well as its signal, so noise falls faster than the square root of bandwidth and a density quoted there is optimistic. Measuring one sensor at two bandwidths and comparing the ratio against the square-root law exposes the extra filtering.
Reversal
H1000. Adding filtering to harden a device against interference can make it more vulnerable to slow drift, since the filter's time constant becomes the longest in the loop and the loop then tracks the drift instead of rejecting it. Injecting drift above and below the filter's corner should show the rejection reversing sign.

Status

100 of 100. Each entry was written on its own terms and labelled by the form of its argument; the labels recur, the sentence structures do not. The forms tracked here run from misattribution and bound through reversal, count, degeneracy, aliasing and closure failure, and several are named for the first time in this file because the argument needed them.

None has been tested. No entry makes a claim about diagnosis, treatment or efficacy; every one is a statement about a physical mechanism and the measurement that would separate it from its alternative. Numbers are order-of-magnitude estimates and are marked where they appear.

Of the hundred, H916 is the one worth an afternoon: a helium-tight package that is not water-tight is a contradiction only if the certificate is believed to be the measurement. A tracer of different mass and a humidity sensor inside the lid would settle it.

Incoprea Research · hand-considered hypotheses 901–1000 · devices and medical physics · 3 November 2026 · ~/Desktop/Nov3/