TODO: whether additional analyses are needed depends on the unavailable results and prespecified questions. An estimated congruence-by-delay interaction can be clarified by the cue-congruence contrast at each delay, with confidence intervals and justified multiple testing control. A direct interaction test addresses whether those contrasts differ; comparing their separate significance labels does not.
Even without a significant interaction, an adequately powered, prespecified contrast may address a distinct scientific question; indiscriminate testing until something is significant is not justified. Inspect regression diagnostics and the treatment of dependent trials where appropriate. Without the output, one cannot decide that any particular follow-up is required or conclude that none is necessary.
TODO: an empirical Results section cannot be completed without the analysis and descriptive output. It must identify the actual factorial design, outcome scale and fitted model; summarize the four condition means with appropriately labeled standard deviations or standard errors; and report the congruence, delay and interaction tests with their actual F-test statistics, statistical degrees of freedom, p-values, effect sizes and relevant confidence intervals.
Interpret an interaction as evidence that the cue-congruence difference varies with delay, not merely as evidence that one separate test was significant and another was not. Any simple-effects analysis must identify its contrasts and multiple testing treatment. If the analysis used transformed reaction times, distinguish the model's scale from raw-second summaries. A nonsignificant result does not establish equality or absence of a theoretically meaningful effect. These are reporting requirements, not placeholders for invented results.
TODO: retrieve both numerator and denominator statistical degrees of freedom for each significant effect from the missing output. The table is also needed to establish which effects, if any, meet the analysis's significance criterion. Participant allocation, exclusions, aggregation and fitted error structure determine the applicable statistical degrees of freedom; the recruitment count is not enough to reconstruct them. No numerical statistical degrees of freedom are asserted here.
TODO: neither the significant effects nor their numerical effect sizes can be determined. Inspect the output's significance results and the definition of its reported effect size. If it supplies partial eta squared, that quantity is ; it is not automatically ordinary eta squared or a fraction of all observed variation. Repeated-measures conventions and the selected error term matter. Report the actual metric and preferably an uncertainty interval; do not manufacture an effect size from the number of participants.
TODO: the effect-specific values are unavailable without the supplementary output. Retrieve the rows for congruence, delay and congruence-by-delay interaction, if those terms were fitted. In an appropriate analysis of variance, each F-test compares a term's mean square in ANOVA with its designated error mean square in ANOVA; repeated observations can require different error terms. Neither the factor labels nor the recruited sample size determines those ratios.
The two independent variables are social-cue congruence, with congruent and incongruent levels, and cue-to-response delay, with short ( ms) and long ( ms) levels. The response variable is reproduction reaction time, measured in seconds. Thus the known treatment structure is a factorial design, potentially estimating two main effects and their interaction.
TODO: identify the allocation from the missing supplementary sheet or protocol. The eighty recruited participants do not establish whether either factor is within-subjects or between-subjects, whether all observations were retained, or how trials were summarized. The design cannot responsibly be called fully repeated-measures, fully independent-groups or mixed without that information.
TODO: the supplementary sheet is needed to identify the analysis actually conducted. A two-factor factorial design is described, but that alone does not distinguish an independent-groups two-way analysis of variance, a repeated-measures analysis of variance, a mixed design, or a mixed-effects model. The model call, error structure, participant allocation and output headings would establish which analysis was used. In particular, the prose does not establish that every participant experienced every condition.
The leading electric dipole radiation fields are
The radiation electric field is transverse, . The vector triple product therefore gives the leading Poynting vector
If is the angle between and , then
Using , the final result is
The leading Poynting flux is outward, vanishes along the instantaneous retarded axis, and is maximal in its perpendicular plane. If , the radiation term is zero and no angle needs to be assigned. The large- expansion assumes bounded retarded electric dipole moment and time derivatives; it may also be read at fixed retarded time.
Set , and , and evaluate , , at . The chain rule gives
In particular, for and any positive integer ,
Apply this gradient identity to the electric potential :
The magnetic vector potential is , with time derivative . Thus the electric field is
For the magnetic field, use the curl product rule and the chain rule:
Consequently the fields of a time-dependent electric dipole include
These formulas hold for . The electric field is the retarded electric dipole field, the terms are induction contributions, and the terms describe electric dipole radiation. Retaining the dependence of on position in every spatial derivative is what produces both the induction and radiation contributions.
Use the sign to label a point charge at , with velocity . All quantities on the right below are evaluated at . To first order,
The denominator in each Liénard–Wiechert potential therefore expands as
so
In the sum of the two electric potentials, the terms cancel and the finite terms add. This gives the retarded potentials of a point electric dipole:
For the magnetic vector potential, the signed electric charge and signed velocity multiply to give the same sign for both contributions:
Since ,
The term in the electric potential arises from the moving-source denominator and remains finite in the point-electric dipole limit; discarding it would fail to give the full retarded electric field.
Take the ideal electric dipole limit with a fixed smooth electric dipole moment , so that ; its required time derivatives are bounded on the time interval under consideration. Fix and put , . For or , the source position is . A Taylor expansion of the distance gives
Substitute this into the defining equation for retarded time:
Boundedness first implies . The Taylor expansion then changes the displayed correction only by . Hence
The nearer positive displacement reduces the propagation distance and consequently increases the retarded time. The Big O notation here is for at a fixed observation event away from the origin. Keeping a fixed smooth is essential: bounded amplitude alone, with arbitrarily increasing time frequency as varies, would not justify this Taylor expansion.
Since , the Poynting vector is axial. The magnetic permeability cancels from in each material layer:
The signed Poynting flux through the plane with unit normal is its surface integral with area element :
Thus
The transmitted electromagnetic energy per unit time is the circuit's terminal power. For , the Poynting flux points in the direction of the inner electric current. The electromagnetic energy travels through the insulating gap and reaches a load at the end of the coaxial cable. The radii and material constants redistribute the electromagnetic energy density and the local Poynting vector, while their integrated Poynting flux depends only on the terminal electric potential difference and electric current.
For this radially layered coaxial cable, define
Use the solution regular at the axis with bounded exterior electric potential, so that the empty interior and exterior have the constant electric potentials fixed by their adjacent conducting cylinders.
There is no free charge in either electrical insulator or on their interface. Gauss's law and continuity of normal electric displacement field give in both layers. The electric potential difference fixes the constant because
The electric potential, including the empty regions bounded by the conducting cylinders, is therefore
Both inner and outer Dirichlet boundary conditions hold, and the electric potential is continuous at the material interface, where
Taking the negative gradient of the electric potential yields
The radial electric field generally jumps at , but , as required by the absence of free surface charge density there. The conducting cylinders carry opposite linear charge densities and .
For an Amperian loop of radius , the enclosed electric current is zero, , or zero according as , , or . The magnetostatic Ampère law therefore gives in the gap, and zero outside. Using the two magnetic permeabilities,
The tangential magnetic field strength is continuous at the material interface, while the tangential magnetic field need not be. At each ideal conducting surface and at the material interface, the displayed electric field and magnetic field formulas specify one-sided limits; a single interface value is unnecessary when the limiting values differ.
Work in cylindrical coordinates and use the assumed independence of and . In each material region, the zero curl of the static electric field gives
The tangential electric field is zero at a perfect conductor. The dielectric-interface boundary conditions make its tangential components continuous at each material interface, so throughout the gap. They also vanish in the empty interior and exterior for the regular solution with no applied external electric field. Hence
This specifies an axis of direction: the sign of depends on the sign of .
For the static magnetic field, Gauss's law for magnetism implies
Thus is constant in each layer. Continuity of the normal magnetic field across every interface makes that constant global, and regularity at the axis makes it zero. Next use away from the conducting surfaces. Its component gives . There is no azimuthal surface current density, so is continuous across the conducting surfaces and the material interface. The decay of the exterior magnetic field at infinity therefore forces this global constant to zero. The only remaining component is
The magnetostatic Ampère law fixes its sign: positive inner electric current in the direction produces positive for positive magnetic permeability.
Allow time dependence while keeping the constitutive relations linear, isotropic, nondispersive, and independent of time. The Maxwell equations in matter give
For the Poynting vector , the divergence identity yields
The first two terms are exact time derivatives. Taking the zero-field energy density as zero gives the electromagnetic energy density
Consequently the Poynting theorem is the continuity equation
In integral form,
The left side is the rate of increase of stored electromagnetic energy plus outward Poynting flux. The right side accounts for work delivered to the free electric current; in an Ohmic medium is the local rate of Joule heating.
Use the constitutive relations and , where is the electric displacement field, the magnetic field strength, the permittivity, and the magnetic permeability. Let be the charge density of free charge and its current density. In this homogeneous medium, Gauss's law and the magnetostatic Ampère law are, respectively,
Here is a volume with closed boundary , and is an oriented spanning surface whose boundary orientation follows the right-hand rule. Thus the electric field form is and ; the magnetic field form is and .
The remaining static Maxwell equations are
These express Gauss's law for magnetism and the static limit of Faraday's law. The volume and circulation forms follow from the divergence theorem and Stokes theorem. The electric charge and electric current on the right of the macroscopic laws are free sources; material electric polarization and magnetization are already included in and .
Write the constant spherical harmonic . Its orthonormality gives , independently of its phase convention. Orthogonality to gives
Only the term contributes to the surface integral of the surface charge density. Multiplying by the surface-area factor gives
Thus the spherical harmonic calculation reproduces the total induced electric charge:
Let and let describe its direction in spherical coordinates; write . The given Dirichlet Green function between concentric spheres has normalization , so the electric potential is . On the inner sphere the unit normal from metal into the gap is , hence its induced surface charge density is
Near this boundary and . The needed radial derivative is
It cancels the factor in the Dirichlet Green function. Therefore the answer in spherical harmonics is
This spherical harmonic expansion converges on the boundary: after the angular sum, the two radial factors decay geometrically with ratios and , while the angular factors grow at most polynomially. This justifies the boundary derivative and the subsequent surface integral.
Choose a spherical Gaussian surface of radius with . Its physical enclosed electric charge is the total induced electric charge on the inner sphere. The method of images produces the same electric field on that Gaussian surface, so Gauss's law identifies with the sum of the enclosed image charges. These are the first family with and the second family with :
Summing these geometric series gives
The electric field in the empty central cavity vanishes by electrostatic shielding, so it contributes no additional inner-face surface charge density. The formula tends to as and to zero as , as expected when the point charge approaches one grounded boundary or the other.
Put and . The complete construction of image charges between concentric grounded spheres consists of two families, indexed by every integer:
The term is the physical point charge; every other term is an image charge. In the first family lies inside and lies outside . In the second family lies inside and lies outside . Thus no image charge lies in the physical gap.
To derive and verify these families, reflection of an axial point charge in a grounded sphere of radius replaces it by the image charge . Reflection in sends to ; reflection in sends it to . Successive reflections therefore generate exactly the listed families. The method of images gives
The physical point charge itself is excluded when evaluating this formula. On , pair the first-family term with the second-family term ; their electric potentials cancel by the single-sphere distance identity. On , pair with instead. These reindexings are justified by absolute convergence, as follows.
For , both source positions tend to the origin while their electric charges have size . On the closed gap their distances are eventually at least , so both electric potential terms are . For , both distances are at least a positive constant times and the electric charges are , giving terms. Both tails are bounded by convergent geometric series. This proves absolute convergence and uniform convergence of the tails on the closed gap. On any compact set avoiding the physical point charge, the differentiated tails obey the same type of bounds: for example, the large positive tail of the electric field is . Thus termwise differentiation is valid and the sum is a harmonic function except at the physical point charge, where it has the correct Coulomb's law singularity. The boundary cancellations and uniqueness of Poisson equation complete the construction.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 5. . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact