Historical background.

In 1905, Albert Einstein postulated the proportionality between the frequency formula_1 of a photon and its energy formula_2, formula_3, and in 1916 the corresponding relation between photon's momentum formula_4 and wavelength formula_5, formula_6, where formula_7 is the Planck constant. In 1923, De Broglie was the first to suggest that the relation formula_8, now called the De Broglie relation, holds for "massive" particles, the chief clue being Lorentz invariance, and this can be viewed as the starting point for the modern development of quantum mechanics. The equations represent wave–particle duality for both massless and massive particles.  In the 1920s and 1930s, quantum mechanics was developed using calculus and linear algebra. Those who used the techniques of calculus included Louis de Broglie, Erwin Schrödinger, and others, developing "wave mechanics". Those who applied the methods of linear algebra included Werner Heisenberg, Max Born, and others, developing "matrix mechanics". Schrödinger subsequently showed that the two approaches were equivalent.  In 1926, Schrödinger published the famous wave equation now named after him, the Schrödinger equation. This equation was based on classical conservation of energy using quantum operators and the de Broglie relations, and the solutions of the equation are the wave functions for the quantum system. However, no one was clear on how to "interpret it". At first, Schrödinger and others thought that wave functions represent particles that are spread out with most of the particle being where the wave function is large. This was shown to be incompatible with the elastic scattering of a wave packet (representing a particle) off a target; it spreads out in all directions. While a scattered particle may scatter in any direction, it does not break up and take off in all directions. In 1926, Born provided the perspective of probability amplitude. This relates calculations of quantum mechanics directly to probabilistic experimental observations. It is accepted as part of the Copenhagen interpretation of quantum mechanics. There are many other interpretations of quantum mechanics. In 1927, Hartree and Fock made the first step in an attempt to solve the "N"-body wave function, and developed the "self-consistency cycle": an iterative algorithm to approximate the solution. Now it is also known as the Hartree–Fock method. The Slater determinant and permanent (of a matrix) was part of the method, provided by John C. Slater.  Schrödinger did encounter an equation for the wave function that satisfied relativistic energy conservation "before" he published the non-relativistic one, but discarded it as it predicted negative probabilities and negative energies. In 1927, Klein, Gordon and Fock also found it, but incorporated the electromagnetic interaction and proved that it was Lorentz invariant. De Broglie also arrived at the same equation in 1928. This relativistic wave equation is now most commonly known as the Klein–Gordon equation.  In 1927, Pauli phenomenologically found a non-relativistic equation to describe spin-1/2 particles in electromagnetic fields, now called the Pauli equation. Pauli found the wave function was not described by a single complex function of space and time, but needed two complex numbers, which respectively correspond to the spin +1/2 and −1/2 states of the fermion. Soon after in 1928, Dirac found an equation from the first successful unification of special relativity and quantum mechanics applied to the electron, now called the Dirac equation. In this, the wave function is a "spinor" represented by four complex-valued components: two for the electron and two for the electron's antiparticle, the positron. In the non-relativistic limit, the Dirac wave function resembles the Pauli wave function for the electron. Later, other relativistic wave equations were found.

Wave functions and wave equations in modern theories.

All these wave equations are of enduring importance. The Schrödinger equation and the Pauli equation are under many circumstances excellent approximations of the relativistic variants. They are considerably easier to solve in practical problems than the relativistic counterparts.  The Klein–Gordon equation and the Dirac equation, while being relativistic, do not represent full reconciliation of quantum mechanics and special relativity. The branch of quantum mechanics where these equations are studied the same way as the Schrödinger equation, often called relativistic quantum mechanics, while very successful, has its limitations (see e.g. Lamb shift) and conceptual problems (see e.g. Dirac sea).  Relativity makes it inevitable that the number of particles in a system is not constant. For full reconciliation, quantum field theory is needed. In this theory, the wave equations and the wave functions have their place, but in a somewhat different guise. The main objects of interest are not the wave functions, but rather operators, so called "field operators" (or just fields where "operator" is understood) on the Hilbert space of states (to be described next section). It turns out that the original relativistic wave equations and their solutions are still needed to build the Hilbert space. Moreover, the "free fields operators", i.e. when interactions are assumed not to exist, turn out to (formally) satisfy the same equation as do the fields (wave functions) in many cases.  Thus the Klein–Gordon equation (spin ) and the Dirac equation (spin ) in this guise remain in the theory. Higher spin analogues include the Proca equation (spin ), Rarita–Schwinger equation (spin ), and, more generally, the Bargmann–Wigner equations. For "massless" free fields two examples are the free field Maxwell equation (spin ) and the free field Einstein equation (spin ) for the field operators. All of them are essentially a direct consequence of the requirement of Lorentz invariance. Their solutions must transform under Lorentz transformation in a prescribed way, i.e. under a particular representation of the Lorentz group and that together with few other reasonable demands, e.g. the "cluster decomposition principle", with implications for causality is enough to fix the equations.  This applies to free field equations; interactions are not included. If a Lagrangian density (including interactions) is available, then the Lagrangian formalism will yield an equation of motion at the classical level. This equation may be very complex and not amenable to solution. Any solution would refer to a "fixed" number of particles and would not account for the term "interaction" as referred to in these theories, which involves the creation and annihilation of particles and not external potentials as in ordinary "first quantized" quantum theory.  In string theory, the situation remains analogous. For instance, a wave function in momentum space has the role of Fourier expansion coefficient in a general state of a particle (string) with momentum that is not sharply defined.

Definition (one spinless particle in one dimension).

For now, consider the simple case of a non-relativistic single particle, without spin, in one spatial dimension. More general cases are discussed below.

Position-space wave functions.

The state of such a particle is completely described by its wave function,  where is position and is time. This is a complex-valued function of two real variables and.  For one spinless particle in 1d, if the wave function is interpreted as a probability amplitude, the square modulus of the wave function, the positive real number  is interpreted as the probability density that the particle is at. The asterisk indicates the complex conjugate. If the particle's position is measured, its location cannot be determined from the wave function, but is described by a probability distribution. The probability that its position will be in the interval is the integral of the density over this interval:  where is the time at which the particle was measured. This leads to the normalization condition:  because if the particle is measured, there is 100% probability that it will be "somewhere".  For a given system, the set of all possible normalizable wave functions (at any given time) forms an abstract mathematical vector space, meaning that it is possible to add together different wave functions, and multiply wave functions by complex numbers (see vector space for details). Technically, because of the normalization condition, wave functions form a projective space rather than an ordinary vector space. This vector space is infinite-dimensional, because there is no finite set of functions which can be added together in various combinations to create every possible function. Also, it is a Hilbert space, because the inner product of two wave functions and can be defined as the complex number (at time )  More details are given below. Although the inner product of two wave functions is a complex number, the inner product of a wave function with itself,  is "always" a positive real number. The number (not ) is called the norm of the wave function.  If, then is normalized. If is not normalized, then dividing by its norm gives the normalized function. Two wave functions and are orthogonal if. If they are normalized "and" orthogonal, they are orthonormal. Orthogonality (hence also orthonormality) of wave functions is not a necessary condition wave functions must satisfy, but is instructive to consider since this guarantees linear independence of the functions. In a linear combination of orthogonal wave functions we have,  If the wave functions were nonorthogonal, the coefficients would be less simple to obtain.  In the Copenhagen interpretation, the modulus squared of the inner product (a complex number) gives a real number  which, assuming both wave functions are normalized, is interpreted as the probability of the wave function "collapsing" to the new wave function upon measurement of an observable, whose eigenvalues are the possible results of the measurement, with being an eigenvector of the resulting eigenvalue. This is the Born rule, and is one of the fundamental postulates of quantum mechanics.  At a particular instant of time, all values of the wave function are components of a vector. There are uncountably infinitely many of them and integration is used in place of summation. In Bra–ket notation, this vector is written  and is referred to as a "quantum state vector", or simply "quantum state". There are several advantages to understanding wave functions as representing elements of an abstract vector space:  The time parameter is often suppressed, and will be in the following. The coordinate is a continuous index. The are the basis vectors, which are orthonormal so their inner product is a delta function;  thus  and  which illuminates the identity operator  Finding the identity operator in a basis allows the abstract state to be expressed explicitly in a basis, and more (the inner product between two state vectors, and other operators for observables, can be expressed in the basis).

Momentum-space wave functions.

The particle also has a wave function in momentum space: where is the momentum in one dimension, which can be any value from to, and is time.  Analogous to the position case, the inner product of two wave functions and can be defined as:  One particular solution to the time-independent Schrödinger equation is a plane wave, which can be used in the description of a particle with momentum exactly, since it is an eigenfunction of the momentum operator. These functions are not normalizable to unity (they aren't square-integrable), so they are not really elements of physical Hilbert space. The set forms what is called the momentum basis. This "basis" is not a basis in the usual mathematical sense. For one thing, since the functions aren't normalizable, they are instead normalized to a delta function, For another thing, though they are linearly independent, there are too many of them (they form an uncountable set) for a basis for physical Hilbert space. They can still be used to express all functions in it using Fourier transforms as described next.

Relations between position and momentum representations.

The and representations are  Now take the projection of the state onto eigenfunctions of momentum using the last expression in the two equations,  Then utilizing the known expression for suitably normalized eigenstates of momentum in the position representation solutions of the free Schrödinger equation  one obtains  Likewise, using eigenfunctions of position,  The position-space and momentum-space wave functions are thus found to be Fourier transforms of each other. The two wave functions contain the same information, and either one alone is sufficient to calculate any property of the particle. As representatives of elements of abstract physical Hilbert space, whose elements are the possible states of the system under consideration, they represent the same state vector, hence "identical physical states", but they are not generally equal when viewed as square-integrable functions.  In practice, the position-space wave function is used much more often than the momentum-space wave function. The potential entering the relevant equation (Schrödinger, Dirac, etc.) determines in which basis the description is easiest. For the harmonic oscillator, and enter symmetrically, so there it doesn't matter which description one uses. The same equation (modulo constants) results. From this follows, with a little bit of afterthought, a factoid: The solutions to the wave equation of the harmonic oscillator are eigenfunctions of the Fourier transform in.

Definitions (other cases).

Following are the general forms of the wave function for systems in higher dimensions and more particles, as well as including other degrees of freedom than position coordinates or momentum components.

One-particle states in 3d position space.

The position-space wave function of a single particle without spin in three spatial dimensions is similar to the case of one spatial dimension above: where is the position vector in three-dimensional space, and is time. As always is a complex-valued function of real variables. As a single vector in Dirac notation  All the previous remarks on inner products, momentum space wave functions, Fourier transforms, and so on extend to higher dimensions.  For a particle with spin, ignoring the position degrees of freedom, the wave function is a function of spin only (time is a parameter);  where is the spin projection quantum number along the axis. (The axis is an arbitrary choice; other axes can be used instead if the wave function is transformed appropriately, see below.) The parameter, unlike and, is a "discrete variable". For example, for a spin-1/2 particle, can only be or, and not any other value. (In general, for spin, can be ). Inserting each quantum number gives a complex valued function of space and time, there are of them. These can be arranged into a column vector  In bra–ket notation, these easily arrange into the components of a vector  The entire vector is a solution of the Schrödinger equation (with a suitable Hamiltonian), which unfolds to a coupled system of ordinary differential equations with solutions. The term "spin function" instead of "wave function" is used by some authors. This contrasts the solutions to position space wave functions, the position coordinates being continuous degrees of freedom, because then the Schrödinger equation does take the form of a wave equation.  More generally, for a particle in 3d with any spin, the wave function can be written in "position–spin space" as: and these can also be arranged into a column vector  in which the spin dependence is placed in indexing the entries, and the wave function is a complex vector-valued function of space and time only.  All values of the wave function, not only for discrete but continuous variables also, collect into a single vector  For a single particle, the tensor product of its position state vector and spin state vector gives the composite position-spin state vector  with the identifications  The tensor product factorization is only possible if the orbital and spin angular momenta of the particle are separable in the Hamiltonian operator underlying the system's dynamics (in other words, the Hamiltonian can be split into the sum of orbital and spin terms). The time dependence can be placed in either factor, and time evolution of each can be studied separately. The factorization is not possible for those interactions where an external field or any space-dependent quantity couples to the spin; examples include a particle in a magnetic field, and spin–orbit coupling.  The preceding discussion is not limited to spin as a discrete variable, the total angular momentum "J" may also be used. Other discrete degrees of freedom, like isospin, can expressed similarly to the case of spin above.

Many-particle states in 3d position space.

If there are many particles, in general there is only one wave function, not a separate wave function for each particle. The fact that "one" wave function describes "many" particles is what makes quantum entanglement and the EPR paradox possible. The position-space wave function for particles is written: where is the position of the th particle in three-dimensional space, and is time. Altogether, this is a complex-valued function of real variables.  In quantum mechanics there is a fundamental distinction between "identical particles" and "distinguishable" particles. For example, any two electrons are identical and fundamentally indistinguishable from each other; the laws of physics make it impossible to "stamp an identification number" on a certain electron to keep track of it. This translates to a requirement on the wave function for a system of identical particles:  where the sign occurs if the particles are "all bosons" and sign if they are "all fermions". In other words, the wave function is either totally symmetric in the positions of bosons, or totally antisymmetric in the positions of fermions. The physical interchange of particles corresponds to mathematically switching arguments in the wave function. The antisymmetry feature of fermionic wave functions leads to the Pauli principle. Generally, bosonic and fermionic symmetry requirements are the manifestation of particle statistics and are present in other quantum state formalisms.  For "distinguishable" particles (no two being identical, i.e. no two having the same set of quantum numbers), there is no requirement for the wave function to be either symmetric or antisymmetric.  For a collection of particles, some identical with coordinates and others distinguishable (not identical with each other, and not identical to the aforementioned identical particles), the wave function is symmetric or antisymmetric in the identical particle coordinates only:  Again, there is no symmetry requirement for the distinguishable particle coordinates.  The wave function for "N" particles each with spin is the complex-valued function  Accumulating all these components into a single vector,  formula_48  For identical particles, symmetry requirements apply to both position and spin arguments of the wave function so it has the overall correct symmetry.  The formulae for the inner products are integrals over all coordinates or momenta and sums over all spin quantum numbers. For the general case of particles with spin in 3d,  this is altogether three-dimensional volume integrals and sums over the spins. The differential volume elements are also written "" or "".  The multidimensional Fourier transforms of the position or position–spin space wave functions yields momentum or momentum–spin space wave functions.

Probability interpretation.

For the general case of particles with spin in 3d, if is interpreted as a probability amplitude, the probability density is  and the probability that particle 1 is in region with spin "and" particle 2 is in region with spin etc. at time is the integral of the probability density over these regions and evaluated at these spin numbers:

Time dependence.

For systems in time-independent potentials, the wave function can always be written as a function of the degrees of freedom multiplied by a time-dependent phase factor, the form of which is given by the Schrödinger equation. For particles, considering their positions only and suppressing other degrees of freedom,  where is the energy eigenvalue of the system corresponding to the eigenstate. Wave functions of this form are called stationary states.  The time dependence of the quantum state and the operators can be placed according to unitary transformations on the operators and states. For any quantum state and operator, in the Schrödinger picture changes with time according to the Schrödinger equation while is constant. In the Heisenberg picture it is the other way round, is constant while evolves with time according to the Heisenberg equation of motion. The Dirac (or interaction) picture is intermediate, time dependence is places in both operators and states which evolve according to equations of motion. It is useful primarily in computing S-matrix elements.

Non-relativistic examples.

The following are solutions to the Schrödinger equation for one nonrelativistic spinless particle.

Finite potential barrier.

One of most prominent features of the wave mechanics is a possibility for a particle to reach a location with a prohibitive (in classical mechanics) force potential. A common model is the "potential barrier", the one-dimensional case has the potential  Note that these wave functions are not normalized; see scattering theory for discussion.  The standard interpretation of this is as a stream of particles being fired at the step from the left (the direction of negative ): setting corresponds to firing particles singly; the terms containing and signify motion to the right, while and – to the left. Under this beam interpretation, put since no particles are coming from the right. By applying the continuity of wave functions and their derivatives at the boundaries, it is hence possible to determine the constants above.  In a semiconductor crystallite whose radius is smaller than the size of its exciton Bohr radius, the excitons are squeezed, leading to quantum confinement. The energy levels can then be modeled using the particle in a box model in which the energy of different states is dependent on the length of the box.

Quantum harmonic oscillator.

The wave functions for the quantum harmonic oscillator can be expressed in terms of Hermite polynomials, they are  where.

Hydrogen atom.

The wave functions of an electron in a Hydrogen atom are expressed in terms of spherical harmonics and generalized Laguerre polynomials (these are defined differently by different authors—see main article on them and the hydrogen atom).  It is convenient to use spherical coordinates, and the wave function can be separated into functions of each coordinate,  where are radial functions and are spherical harmonics of degree and order. This is the only atom for which the Schrödinger equation has been solved exactly. Multi-electron atoms require approximative methods. The family of solutions is:  where  These quantum numbers index the components of the state vector. More, all are in an -dimensional set where each is the set of allowed values for ; all are in an -dimensional "volume" where and each is the set of allowed values for, a subset of the real numbers. For generality and are not necessarily equal.  Example:  (a) For a single particle in 3d with spin "s", neglecting other degrees of freedom, using Cartesian coordinates, we could take for the spin quantum number of the particle along the z direction, and for the particle's position coordinates. Here is the set of allowed spin quantum numbers and is the set of all possible particle positions throughout 3d position space.  (b) An alternative choice is for the spin quantum number along the y direction and for the particle's momentum components. In this case and are the same as before.  The probability density of finding the system at time formula_57at state is  The probability of finding system with in some or all possible discrete-variable configurations,, and in some or all possible continuous-variable configurations,, is the sum and integral over the density,  Since the sum of all probabilities must be 1, the normalization condition  must hold at all times during the evolution of the system.  The normalization condition requires to be dimensionless, by dimensional analysis must have the same units as.

Ontology.

Whether the wave function really exists, and what it represents, are major questions in the interpretation of quantum mechanics. Many famous physicists of a previous generation puzzled over this problem, such as Schrödinger, Einstein and Bohr. Some advocate formulations or variants of the Copenhagen interpretation (e.g. Bohr, Wigner and von Neumann) while others, such as Wheeler or Jaynes, take the more classical approach and regard the wave function as representing information in the mind of the observer, i.e. a measure of our knowledge of reality. Some, including Schrödinger, Bohm and Everett and others, argued that the wave function must have an objective, physical existence. Einstein thought that a complete description of physical reality should refer directly to physical space and time, as distinct from the wave function, which refers to an abstract mathematical space.

A wave function in quantum physics is a mathematical description of the quantum state of an isolated quantum system. The wave function is a complex-valued probability amplitude, and the probabilities for the possible results of measurements made on the system can be derived from it. The most common symbols for a wave function are the Greek letters and (lower-case and capital psi, respectively).

Ve fyzice a v matematice obecně je vlnová funkce řešení libovolné vlnové rovnice, která je obvykle parciální diferenciální rovnicí prvního či druhého řádu. S vlnovými rovnicemi se setkáme jak v klasické fyzice, například v teorii elektromagnetického pole, tak v moderní fyzice.


Signs and symptoms.

The most common signs of jaundice in adults are a yellowish discoloration of the white area of the eye (sclera) and skin with scleral icterus presence indicating a serum bilirubin of at least 3 mg/dL. Other common signs include dark urine (bilirubinuria) and pale, fatty stool (steatorrhea). Because bilirubin is a skin irritant, jaundice is commonly associated with severe itchiness.  Eye conjunctiva have a particularly high affinity for bilirubin deposition due to high elastin content. Slight increases in serum bilirubin can therefore be detected early on by observing yellowing of sclerae. Traditionally referred to as "scleral icterus," this term is actually a misnomer because bilirubin deposition technically occurs in the conjunctival membranes overlying the avascular sclera. Thus, the proper term for the yellowing of "white of the eyes" is "conjunctival icterus".  A much less common sign of jaundice specifically during childhood is yellowish or greenish teeth. In developing children, hyperbilirubinemia may cause a yellow or green discoloration of teeth due to bilirubin deposition during the process of teeth calcification. While this may occur in children with hyperbilirubinemia, teeth discoloration due to hyperbilirubinemia is not observed in individuals with adult-onset liver disease. Disorders associated with a rise in serum levels of conjugated bilirubin during early development can also cause dental hypoplasia.

Causes.

Jaundice is a sign indicating the presence of an underlying diseases involving abnormal bilirubin metabolism, liver dysfunction, or biliary tract obstruction. In general, jaundice is present when blood levels of bilirubin exceed 3 mg/dL. Jaundice is classified into three categories, depending on which part of the physiological mechanism the pathology affects. The three categories are:

Pre-hepatic Causes.

Pre-hepatic jaundice is most commonly caused by a pathological increased rate of red blood cell (erythrocyte) hemolysis. The increased breakdown of erythrocytes → increased unconjugated serum bilirubin → increased deposition of unconjugated bilirubin into mucosal tissue. The following diseases may cause jaundice due to increased erythrocyte hemolysis:

Hepatic Causes.

Hepatic jaundice is caused by abnormal liver metabolism of bilirubin. The major causes of hepatic jaundice are significant damage to hepatocytes — due to infectious, drug/medication-induced, auto-immune etiology — or, less commonly, due to inheritable genetic diseases. The following is a non-exhaustive list of hepatic causes to jaundice:

Post-hepatic Causes.

Post-hepatic jaundice (obstructive jaundice), is caused by a blockage of bile ducts which transport bile containing conjugated bilirubin out of the liver for excretion. The following is a list of conditions that can cause post-hepatic jaundice:

Pathophysiology.

Jaundice is typically caused by an underlying pathological process that occurs at some point along the normal physiological pathway heme metabolism. A deeper understanding of the anatomical flow of normal heme metabolism is essential to appreciate the importance of pre-hepatic, hepatic, and post-hepatic categories. Thus, an anatomical approach to heme metabolism precedes a discussion of the pathophysiology of jaundice.

Normal Heme Metabolism.

Pre-hepatic Metabolism.

When red blood cells complete their life span of approximately 120 days, or if they are damaged, they rupture as they pass through the reticuloendothelial system and cell content including hemoglobin is released into circulation. Macrophages phagocytose free hemoglobin and split them into heme and globin. Two reactions then take place with the heme molecule. The first oxidation reaction is catalyzed by the microsomal enzyme heme oxygenase and results in biliverdin (green color pigment), iron, and carbon monoxide. The next step is the reduction of biliverdin to a yellow color tetrapyrrole pigment called bilirubin by cytosolic enzyme biliverdin reductase. This bilirubin is "unconjugated," "free" or "indirect" bilirubin. Approximately 4 milligrams of bilirubin per kilogram of blood is produced each day. The majority of this bilirubin comes from the breakdown of heme from expired red blood cells in the process just described. Approximately twenty percent comes from other heme sources, however, including ineffective erythropoiesis, and the breakdown of other heme-containing proteins, such as muscle myoglobin and cytochromes. The unconjugated bilirubin then travels to the liver through the bloodstream. Because this bilirubin is not soluble, it is transported through the blood bound to serum albumin.

Hepatic Metabolism.

Once unconjugated bilirubin arrives in the liver, a liver enzyme UDP-glucuronyl transferase conjugates bilirubin + glucuronic acid → bilirubin diglucuronide (conjugated bilirubin). Bilirubin that has been conjugated by the liver is water-soluble and excreted into the gallbladder.

Post-hepatic Metabolism.

Bilirubin enters the intestinal tract via bile. In the intestinal tract, bilirubin is converted into urobilinogen by symbiotic intestinal bacteria. Most urobilinogen is converted into stercobilinogen and further oxidized into stercobilin. Stercobilin is excreted via feces, giving stool its characteristic brown coloration. A small portion of urobilinogen is reabsorbed back into the gastrointestinal cells. Most reabsorbed urobilinogen undergoes hepatobiliary recirculation. A smaller portion of reabsorbed urobilinogen is filtrated into the kidneys. In the urine, urobilinogen is converted to urobilin, which gives urine its characteristic yellow color.

Abnormalities in Heme Metabolism and Excretion.

One way to understand jaundice pathophysiology is to organize it into disorders that cause increased bilirubin production (abnormal heme metabolism) or decreased bilirubin excretion (abnormal heme excretion).

Pre-hepatic Pathophysiology.

Pre-hepatic jaundice is attributed to a pathologic increase in bilirubin production. The pathophysiology is quite simple: an increased rate of erythrocyte hemolysis → increased bilirubin production → increased deposition of bilirubin in mucosal tissue → appearance of yellow hue.

Hepatic Pathophysiology.

Hepatic jaundice (hepatocellular jaundice) is due to significant damage to liver function → hepatic cell death and necrosis occur → impaired bilirubin transport across hepatocytes. Bilirubin transport across hepatocytes may be impaired at any point between hepatocellular uptake of unconjugated bilirubin and hepatocellular transport of conjugated bilirubin into the gallbladder. In addition, subsequent cellular edema due to inflammation causes mechanical obstruction of intrahepatic biliary tract. Most commonly, interferences in all three major steps of bilirubin metabolism — uptake, conjugation, and excretion — usually occur in hepatocellular jaundice. Thus, an abnormal rise in both unconjugated and conjugated bilirubin will be present. Because excretion (the rate-limiting step) is usually impaired to the greatest extent, conjugated hyperbilirubinemia predominates.  The unconjugated bilirubin still enters the liver cells and becomes conjugated in the usual way. This conjugated bilirubin is then returned to the blood, probably by rupture of the congested bile canaliculi and direct emptying of the bile into the lymph leaving the liver. Thus, most of the bilirubin in the plasma becomes the conjugated type rather than the unconjugated type, and this conjugated bilirubin, which did not go to intestine to become urobilinogen, gives the urine the dark color.  Bilirubinuria is due to excess conjugated bilirubin excreted in the urine.

Post-hepatic Pathophysiology.

Post-hepatic jaundice (obstructive jaundice) is due to a blockage of bile excretion from the biliary tract → increased conjugated bilirubin and bile salts. In complete obstruction of the bile duct, conjugated bilirubin cannot access the intestinal tract → no further bilirubin conversion to urobilinogen → no stercobilin or urobilin. Instead, excess conjugated bilirubin is filtrated into the urine without urobilinogen in obstructive jaundice. Conjugated bilirubin in urine (bilirubinuria) gives urine an abnormally dark brown color. Thus, the presence of pale stool (stercobilin absent from feces) and dark urine (conjugated bilirubin present in urine) suggest an obstructive cause of jaundice. Because these associated signs are also positive in many hepatic jaundice conditions, they cannot be a reliable clinical feature to distinguish obstruction versus hepatocellular jaundice causes.

Diagnosis.

Most people presenting with jaundice will have various predictable patterns of liver panel abnormalities, though significant variation does exist. The typical liver panel will include blood levels of enzymes found primarily from the liver, such as the aminotransferases (ALT, AST), and alkaline phosphatase (ALP); bilirubin (which causes the jaundice); and protein levels, specifically, total protein and albumin. Other primary lab tests for liver function include gamma glutamyl transpeptidase (GGT) and prothrombin time (PT). No single test can differentiate between various classifications of jaundice. A combination of liver function tests as well as other physical exam findings is essential to arrive at a diagnosis.

Labs.

Some bone and heart disorders can lead to an increase in ALP and the aminotransferases, so the first step in differentiating these from liver problems is to compare the levels of GGT, which will only be elevated in liver-specific conditions. The second step is distinguishing from biliary (cholestatic) or liver causes of jaundice and altered laboratory results. ALP and GGT levels will typically rise with one pattern while aspartate aminotransferase (AST) and alanine aminotransferase (ALT) rise in a separate pattern. If the ALP (10–45 IU/L) and GGT (18–85 IU/L) levels rise proportionately as high as the AST (12–38 IU/L) and ALT (10–45 IU/L) levels, this indicates a cholestatic problem. On the other hand, if the AST and ALT rise is significantly higher than the ALP and GGT rise, this indicates a liver problem. Finally, distinguishing between liver causes of jaundice, comparing levels of AST and ALT can prove useful. AST levels will typically be higher than ALT. This remains the case in most liver disorders except for hepatitis (viral or hepatotoxic). Alcoholic liver damage may see fairly normal ALT levels, with AST 10 times higher than ALT. On the other hand, if ALT is higher than AST, this is indicative of hepatitis. Levels of ALT and AST are not well correlated to the extent of liver damage, although rapid drops in these levels from very high levels can indicate severe necrosis. Low levels of albumin tend to indicate a chronic condition, while it is normal in hepatitis and cholestasis.  Lab results for liver panels are frequently compared by the magnitude of their differences, not the pure number, as well as by their ratios. The AST:ALT ratio can be a good indicator of whether the disorder is alcoholic liver damage (above 10), some other form of liver damage (above 1), or hepatitis (less than 1). Bilirubin levels greater than 10 times normal could indicate neoplastic or intrahepatic cholestasis. Levels lower than this tend to indicate hepatocellular causes. AST levels greater than 15 times normal tend to indicate acute hepatocellular damage. Less than this tend to indicate obstructive causes. ALP levels greater than 5 times normal tend to indicate obstruction, while levels greater than 10 times normal can indicate drug (toxin) induced cholestatic hepatitis or cytomegalovirus infection. Both of these conditions can also have ALT and AST greater than 20 times normal. GGT levels greater than 10 times normal typically indicate cholestasis. Levels 5–10 times tend to indicate viral hepatitis. Levels less than 5 times normal tend to indicate drug toxicity. Acute hepatitis will typically have ALT and AST levels rising 20–30 times normal (above 1000), and may remain significantly elevated for several weeks. Acetaminophen toxicity can result in ALT and AST levels greater than 50 times normal.  Laboratory findings depend on the cause of jaundice.  Unconjugated bilirubin is hydrophobic and therefore cannot be excreted in urine. Thus, the finding of increased urobilinogen in the urine without the presence of bilirubin in the urine (due to its unconjugated state) suggests hemolytic jaundice as the underlying disease process. Urobilinogen will be greater than 2 units (i.e., hemolytic anemia causes increased heme metabolism; exception: infants where gut flora has not developed). Conversely, conjugated bilirubin is hydrophilic and thus can be detected as present in the urine — bilirubinuria — in contrast to unconjugated bilirubin which is absent in the urine.

Imaging.

Medical imaging such as ultrasound, CT scan, and HIDA scans are useful for detecting bile duct blockage.

Differential diagnosis.

Yellow discoloration of the skin, especially on the palms and the soles, but not of the sclera or inside the mouth is due to carotenemia—a harmless condition.

Treatment.

Treatment of jaundice will vary depending on the underlying cause. If a bile duct blockage is present, surgery is typically required; otherwise, management will be medical. Surgery in patients with obstructive jaundice are associated with significantly higher rates of complications (69% vs 38%, P=0.002) and mortality. Medical management may involve treating infectious causes and stopping medication that could be contributing to the jaundice. The itchiness may be helped by draining the gallbladder or ursodeoxycholic acid.

Complications.

Hyperbilirubinemia, more precisely hyperbilirubinemia due to the unconjugated fraction, may cause bilirubin to accumulate in the gray matter of the central nervous system, potentially causing irreversible neurological damage leading to a condition known as kernicterus. Depending on the level of exposure, the effects range from unnoticeable to severe brain damage and even death. Newborns are especially vulnerable to hyperbilirubinemia-induced neurological damage and therefore must be carefully monitored for alterations in their serum bilirubin levels.  Individuals with parenchymal liver disease who have impaired hemostasis may develop bleeding problems.

Epidemiology.

Jaundice in adults is rare. Under the five year DISCOVERY programme in the UK, annual incidence of jaundice was 0.74 per 1000 individuals over age 45, although this rate may be slightly inflated due to the main goal of the programme collecting and analyzing cancer data in the population. Jaundice is commonly associated with severity of disease with an incidence of up to 40% of patients requiring intensive care in ICU experiencing jaundice. The causes of jaundice in the intensive care setting is both due to jaundice as the primary reason for ICU stay or as a morbidity to an underlying disease (i.e. sepsis).  In the developed world, the most common causes of jaundice are blockage of the bile duct or medication-induced. In the developing world, the most common cause of jaundice is infectious such as viral hepatitis, leptospirosis, schistosomiasis, or malaria.

Risk factors.

Risk factors associated with high serum bilirubin levels include male gender, white ethnicities, and active smoking. Mean serum total bilirubin levels in adults were found to be higher in men (0.72 ± 0.004 mg/dL) than women (0.52 ± 0.003 mg/dL). Higher bilirubin levels in adults are found also in non-Hispanic white population (0.63 ± 0.004 mg/dL) and Mexican American population (0.61 ± 0.005 mg/dL) while lower in non-Hispanic black population (0.55 ± 0.005 mg/dL). Bilirubin levels are higher in active smokers.

Special Populations.

Neonatal Jaundice.

Symptoms.

Jaundice in infants presents with yellowed skin and icteral sclerae. Neonatal jaundice spreads in a cephalo-caudal pattern, affecting the face and neck before spreading down to the trunk and lower extremities in more severe cases. Other symptoms may include drowsiness, poor feeding, and in severe cases, unconjugated bilirubin can cross the blood-brain barrier and cause permanent neurological damage (kernicterus).

Causes.

The most common cause of jaundice in infants is normal physiologic jaundice. Pathologic causes of neonatal jaundice include the following:

Pathophysiology.

Transient neonatal jaundice is one of the most common conditions occurring in newborns (children under 28 days of age) with more than eighty percent affected during their first week of life. Jaundice in infants, like adults, is characterized by increased bilirubin levels (total serum bilirubin greater than 5 mg/dL).  Normal physiological neonatal jaundice is due to immaturity of liver enzymes involved in bilirubin metabolism, immature gut microbiota, and increased breakdown of fetal hemoglobin (HbF). Breastmilk jaundice is caused by an increased concentration of β-glucuronidase in breast milk → ↑ deconjugation and reabsorption of bilirubin → persistence of physiologic jaundice with unconjugated hyperbilirubinemia. Onset of breastmilk jaundice is within 2 weeks after birth and lasts for 4–13 weeks.  While most cases of newborn jaundice are not harmful, if bilirubin levels are very high, brain damage — kernicterus — may occur leading to significant disability. Kernicterus is associated with increased unconjugated bilirubin (which is not carried by albumin). Newborns are especially vulnerable to this due to increased permeability of the blood–brain barrier and increased unconjugated bilirubin given fetal hemoglobin breakdown and immature gut flora. This condition has been rising in recent years due to less time spent outdoors.

Treatment.

Jaundice in newborns is usually transient and dissipates without medical intervention. In cases when serum bilirubin levels are greater than 4–21 mg/dL (68-360 μmol/L), infant may be treated with phototherapy or exchanged transfusion depending on the infant's age and prematurity status. A Bili light is often the tool used for early treatment, which often consists of exposing the baby to intensive phototherapy. Sunbathing is effective treatment, and has the advantage of ultra-violet-B, which promotes vitamin D production. Bilirubin count is also lowered through excretion — bowel movements and urination —so frequent and effective feedings are vital measures to decrease jaundice in infants.

Etymology.

Jaundice comes from the French "jaune", meaning yellow, "jaunisse" meaning "yellow disease". The medical term for it is icterus from the Greek word "ikteros". The origin of the word icterus is quite bizarre, coming from an ancient belief that jaundice could be cured from looking at the yellow bird "icteria". The term "icterus" is sometimes incorrectly used to refer to jaundice specifically of sclera.

Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and whites of the eyes due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of an underlying diseases involving abnormal heme metabolism, liver dysfunction, or biliary tract obstruction. The prevalence of jaundice in adults is rare, while jaundice in babies is common with an estimated eighty percent affected during their first week of life. The most common associated symptoms of jaundice are itchiness, pale feces, and dark urine. Normal levels of bilirubin in blood are below 1.0 mg/dL (17 μmol/L), while levels over 2–3 mg/dL (34-51 μmol/L) typically result in jaundice. High blood bilirubin is divided into two types: unconjugated bilirubin and conjugated bilirubin. Causes of jaundice vary from non-serious to potentially fatal. High unconjugated bilirubin may be due to excess red blood cell breakdown, large bruises, genetic conditions such as Gilbert's syndrome, not eating for a prolonged period of time, newborn jaundice, or thyroid problems. High conjugated bilirubin may be due to liver diseases such as cirrhosis or hepatitis, infections, medications, or blockage of the bile duct. Blockage of the bile duct may occur due to gallstones, cancer, or pancreatitis. Other conditions can also cause yellowish skin, but are not jaundice, including carotenemia — which can develop from eating large amounts of foods containing carotene — or medications like rifampin. Treatment of jaundice is typically determined by the underlying cause. If a bile duct blockage is present, surgery is typically required; otherwise, management is medical. Medical management may involve treating infectious causes and stopping medication that could be contributing to the jaundice. Jaundice in newborns may be treated with phototherapy or exchanged transfusion depending on age and prematurity when the bilirubin is greater than 4–21 mg/dL (68-360 μmol/L). The itchiness may be helped by draining the gallbladder or ursodeoxycholic acid. The word "jaundice" is from the French "jaunisse", meaning "yellow disease".

Žloutenka (: "icterus") je patologický stav, který se klinicky projevuje zežloutnutím kůže, očního bělma, sliznic i ostatních tkání. To je způsobeno zvýšenou koncentrací žlutého žlučového barviva bilirubinu v krevní plazmě.


Etymology.

The Japanese term "kōan" is the Sino-Japanese reading of the Chinese word "gong'an" (). The term is a compound word, consisting of the characters "public; official; governmental; common; collective; fair; equitable" and "table; desk; (law) case; record; file; plan; proposal."  According to the Yuan dynasty Zen master Zhongfeng Mingben ( 1263–1323), "gōng'àn" originated as an abbreviation of "gōngfǔ zhī àndú" (, Japanese "kōfu no antoku"—literally the "andu" "official correspondence; documents; files" of a "gongfu" "government post"), which referred to a "public record" or the "case records of a public law court" in Tang dynasty China. "Kōan/gong'an" thus serves as a metaphor for principles of reality beyond the private opinion of one person, and a teacher may test the student's ability to recognize and understand that principle.  Commentaries in kōan collections bear some similarity to judicial decisions that cite and sometimes modify precedents. An article by T. Griffith Foulk claims "Gong'an" was itself originally a metonym—an article of furniture involved in setting legal precedents came to stand for such precedents. For example, "Di Gong'an" () is the original title of "Celebrated Cases of Judge Dee", the famous Chinese detective novel based on a historical Tang dynasty judge. Similarly, Zen kōan collections are public records of the notable sayings and actions of Zen masters and disciples attempting to pass on their teachings.

Origins and development.

China.

Commenting on old cases.

Gong'ans developed during the Tang dynasty (618–907) from the recorded sayings collections of Chán-masters, which quoted many stories of "a famous past Chán figure's encounter with disciples or other interlocutors and then offering his own comment on it". Those stories and the accompanying comments were used to educate students, and broaden their insight into the Buddhist teachings.  Those stories came to be known as gongan, "public cases". Such a story was only considered a gongan when it was commented upon by another Chán-master. This practice of commenting on the words and deeds of past masters confirmed the master's position as an awakened master in a lineage of awakened masters of the past.

Literary practice.

Koan practice developed from a literary practice, styling snippets of encounter-dialogue into well-edited stories. It arose in interaction with "educated literati". There were dangers involved in such a literary approach, such as ascribing specific meanings to the cases. Dahui Zonggao is even said to have burned the woodblocks of the "Blue Cliff Record", for the hindrance it had become to study of Chán by his students. Kōan literature was also influenced by the pre-Zen Chinese tradition of the "literary game"—a competition involving improvised poetry.  The style of writing of Zen texts has been influenced by "a variety of east Asian literary games":

Observing the phrase.

During the Song dynasty (960–1297) the use of gongans took a decisive turn. Dahui Zonggao (1089–1163) introduced the use of "kanhua", "observing the phrase". In this practice students were to observe ("kan") or concentrate on a single word or phrase ("huatou"), such as the famous "mu" of the mu-koan.  In the eleventh century this practice had become common. A new literary genre developed from this tradition as well. Collections of such commented cases were compiled which consisted of the case itself, accompanied by verse or prose commentary.  Dahui's invention was aimed at balancing the insight developed by reflection on the teachings with developing samatha, calmness of mind. Ironically, this development became in effect "silent illumination", a "[re-absorbing] of koan-study into the "silence" of meditation ("ch'an")". It led to a rejection of Buddhist learning: This development left Chinese Chan vulnerable to criticisms by neo-Confucianism, which developed after the Sung Dynasty. Its anti-intellectual rhetoric was no match for the intellectual discourse of the neo-Confucianists.

Interaction.

The recorded encounter dialogues, and the koan collections which derived from this genre, mark a shift from solitary practice to interaction between master and student: This mutual enquiry of the meaning of the encounters of masters and students of the past gave students a role model: Kōan training requires a qualified teacher who has the ability to judge a disciple's depth of attainment. In the Rinzai Zen school, which uses kōans extensively, the teacher certification process includes an appraisal of proficiency in using that school's extensive kōan curriculum.

Contemporary koan-use.

In China and Korea, "observing the phrase" is still the sole form of koan-practice, though Seung Sahn used the Rinzai-style of koan-practice in his Kwan Um School of Zen.

Japan.

Japanese Zen, both Rinzai and Sōtō, took over the use of koan-study and commenting. In Sōtō-Zen, koan commentary was not linked to seated meditation.

Koan manuals.

When the Chán-tradition was introduced in Japan, Japanese monks had to master the Chinese language and specific expressions used in the koan-training. The desired "spontaneity" expressed by enlightened masters required a thorough study of Chinese language and poetry. Japanese Zen imitated the Chinese "syntax and stereotyped norms".  In the officially recognized monasteries belonging to the Gozan (Five Mountain System) the Chinese system was fully continued. Senior monks were supposed to compose Chinese verse in a complex style of matched counterpoints known as "bienli wen". It took a lot of literary and intellectual skills for a monk to succeed in this system.  The Rinka-monasteries, the provincial temples with less control of the state, laid less stress on the correct command of the Chinese cultural idiom. These monasteries developed "more accessible methods of koan instruction". It had three features:  By standardizing the koan-curriculum every generation of students proceeded to the same series of koans. Students had to memorize a set number of stereotyped sayings, "agyō", "appended words". The proper series of responses for each koan were taught by the master in private instruction-sessions to selected individual students who would inherit the dharma lineage.  "Missanroku" and "missanchō", "Records of secret instruction" have been preserved for various Rinzai-lineages. They contain both the koan-curricula and the standardized answers. In Sōtō-Zen they are called "monsan", an abbreviation of "monto hissan", "secret instructions of the lineage". The "monsan" follow a standard question-and-answer format. A series of questions is given, to be asked by the master. The answers are also given by the master, to be memorized by the student.

Contemporary koan curricula.

In the eighteenth century the Rinzai school became dominated by the legacy of Hakuin, who laid a strong emphasis on koan study as a means to gain kensho and develop insight. There are two curricula used in Rinzai, both derived from the principal heirs of Rinzai: the Takuju curriculum, and the Inzan curriculum. According to AMA Samy, "the koans and their standard answers are fixed."

Suppression in the Sōtō-school.

During the late eighteenth and nineteenth century the tradition of koan-commentary became suppressed in the Sōtō-school, due to a reform movement that sought to standardise the procedures for dharma transmission. One reason for suppressing the koan-tradition in the Sōtō-school may have been to highlight the differences with the Rinzai-school, and create a clear identity. This movement also started to venerate Dogen as the founding teacher of the Sōtō-school. His teachings became the standard for the Sōtō-teachings, neglecting the fact that Dogen himself made extensive use of koan-commentary.

Doctrinal background.

The popular western understanding sees "kōan" as referring to an unanswerable question or a meaningless statement. However, in Zen practice, a kōan is not meaningless, and not a riddle or a puzzle. Teachers do expect students to present an appropriate response when asked about a kōan.  Koans are also understood as pointers to an unmediated "Pure Consciousness", devoid of cognitive activity. Victor Hori criticizes this understanding: According to Hori, a central theme of many koans is the 'identity of opposites': Comparable statements are: "Look at the flower and the flower also looks"; "Guest and host interchange".

Koan-practice.

Study of kōan literature is common to all schools of Zen, though with varying emphases and curricula. The Rinzai-school uses extensive koan-curricula, checking questions, and "jakogo" ("capping phrases", quotations from Chinese poetry) in its use of koans. The Sanbo Kyodan, and its western derivates of Taizan Maezumi and the White Plum Asanga, also use koan-curricula, but have omitted the use of capping phrases. In Chinese Chán and Korean Seon, the emphasis is on Hua Tou, the study of one koan throughout one's lifetime. In Japanese Sōtō Zen, the use of koans has been abandoned since the late eighteenth and nineteenth century.

Hua-tou or breakthrough-koan.

In the Rinzai-school, the Sanbo Kyodan, and the White Plum Asanga, koan practice starts with the assignment of a "hosshi" or "break-through koan", usually the mu-koan or "the sound of one hand clapping". In Chinese Chán and Korean Seon, various koan can be used for the hua-tou practice.  Students are instructed to concentrate on the "word-head", like the phrase "mu". In the Wumenguan (Mumonkan), public case No. 1 ("Zhaozhou's Dog"), Wumen (Mumon) wrote: Arousing this great inquiry or "Great Doubt" is an essential element of kōan practice. It builds up "strong internal pressure ("gidan"), never stopping knocking from within at the door of [the] mind, demanding to be resolved". To illustrate the enormous concentration required in kōan meditation, Zen Master Wumen commented, Analysing the koan for its literal meaning won't lead to insight, though understanding the context from which koans emerged can make them more intelligible. For example, when a monk asked Zhaozhou (Joshu) "does a dog have Buddha-nature or not?", the monk was referring to the understanding of the teachings on Buddha-nature, which were understood in the Chinese context of absolute and relative reality.

Insight.

The continuous pondering of the break-through koan ("shokan") or Hua Tou, "word head", leads to kensho, an initial insight into "seeing the (Buddha-)nature.  The aim of the break-through koan is to see the "nonduality of subject and object": Various accounts can be found which describe this "becoming one" and the resulting breakthrough: But the use of the mu-koan has also been criticised. According to AMA Samy, the main aim is merely to "'become one' with the koan". Showing to have 'become one' with the first koan is enough to pass the first koan. According to Samy, this is not equal to prajna:

Testing insight - or learning responses.

Sassho – Checking questions.

Teachers may probe students about their kōan practice using "sassho", "checking questions" to validate their satori (understanding) or kensho (seeing the nature). For the "mu-koan" and the "clapping hand-koan" there are twenty to a hundred checking questions, depending on the teaching lineage. The checking questions serve to deepen the insight of the student, but also to test his or her understanding.  Those checking questions, and their answers, are part of a standardised set of questions and answers. Students are learning a "ritual performance", learning how to behave and respond in specific ways, learning "clever repartees, ritualized language and gestures and be submissive to the master’s diktat and arbitration."

Jakugo – Capping phrases.

In the Rinzai-school, passing a koan and the checking questions has to be supplemented by "jakugo", "capping phrases", citations of Chinese poetry to demonstrate the insight. Students can use collections of those citations, instead of composing poetry themselves.

Post-satori practice.

After the initial insight further practice is necessary, to deepen the insight and learn to express it in daily life. In Chinese Chán and Korean Seon, this further practice consists of further pondering of the same Hua Tou. In Rinzai-Zen, this further practice is undertaken by further koan-study, for which elaborate curricula exist. In Sōtō-Zen, Shikantaza is the main practice for deepening insight.

Varieties in koan-practice.

Chinese Chán and Korean Seon.

In Chinese Chán and Korean Seon, the primary form of Koan-study is "kanhua", "reflection on the koan", also called Hua Tou, "word head". In this practice, a fragment of the koan, such as ""mu"", or a "what is"-question is used by focusing on this fragment and repeating it over and over again: The student is assigned only one hua-tou for a lifetime. In contrast to the similar-sounding "who am I?" question of Ramana Maharshi, hua-tou involves raising "great doubt":

Japanese Rinzai.

Kōan practice is particularly important among Japanese practitioners of the Rinzai sect.

Importance of koan-study.

This importance is reflected in writings in the Rinzai-school on the koan-genre. Zhongfeng Mingben (1263–1323), a Chinese Chán-master who lived at the beginning of the Yuan Dynasty, revitalized the Rinzai-tradition, and put a strong emphasis on the use of koans. He saw the kung-ans as "work of literature [that] should be used as objective, universal standards to test the insight of monks who aspired to be recognized as Ch'an masters": Musō Soseki (1275–1351), a Japanese contemporary of Zhongfeng Mingben, relativized the use of koans. The study of koans had become popular in Japan, due to the influence of Chinese masters such as Zhongfeng Mingben. Despite belonging to the Rinzai-school, Musō Soseki also made extensive use of "richi" (teaching), explaining the sutras, instead of "kikan" (koan). According to Musō Soseki, both are "upaya", "skillful means" meant to educate students. Musō Soseki called both "shōkogyu", "little jewels", tools to help the student to attain satori.

Koan curricula.

In Rinzai a gradual succession of koans is studied. There are two general branches of curricula used within Rinzai, derived from the principal heirs of Rinzai: the Takuju curriculum, and the Inzan curriculum. However, there are a number of sub-branches of these, and additional variations of curriculum often exist between individual teaching lines which can reflect the recorded experiences of a particular lineage's members. Koan curricula are, in fact, subject to continued accretion and evolution over time, and thus are best considered living traditions of practice rather than set programs of study.  Koan practice starts with the "shokan", or "first barrier", usually the mu-koan or the koan "What is the sound of one hand clapping?" After having attained "kensho", students continue their practice investigating subsequent koans. In the Takuju-school, after breakthrough students work through the "Gateless Gate" (Mumonkan), the "Blue Cliff Record" (Hekigan-roku), the "Entangling Vines" (Shumon Kattoshu), and the "Collection of Wings of the Blackbird" (, "Chin'u shū"). The Inzan-school uses its own internally generated list of koans.  Hakuin's descendants developed a fivefold classification system:  According to Akizuki there was an older classification-system, in which the fifth category was "Kojo", "Directed upwards". This category too was meant to rid the monk of any "stink of Zen". The very advanced practitioner may also receive the "Matsugo no rokan", "The last barrier, and "Saigo no ikketsu", "The final confirmation". "The last barrier" when one left the training hall, for example "Sum up all of the records of Rinzai in one word!" It is not meant to be solved immediately, but to be carried around in order to keep practising. "the final confirmation" may be another word for the same kind of koan.

Post-satori practice.

Completing the koan-curriculum in the Rinzai-schools traditionally also led to a mastery of Chinese poetry and literary skills: After completing the koan-training, "Gogo no shugyo", post-satori training is necessary:

Breathing practices.

Hakuin Ekaku, the 17th century revitalizer of the Rinzai school, taught several practices which serve to correct physical and mental imbalances arising from, among other things, incorrect or excessive koan practice. The "soft-butter" method ("nanso no ho") and "introspection method" ("naikan no ho") involve cultivation of ki centered on the tanden (Chinese:dantian). These practices are described in Hakuin's works Orategama and Yasen Kanna, and are still taught in some Rinzai lineages today.

Japanese Sōtō.

Though few Sōtō practitioners concentrate on kōans during meditation, the Sōtō sect has a strong historical connection with kōans, since many kōan collections were compiled by Sōtō priests.  During the 13th century, Dōgen, founder of the Sōtō sect in Japan, quoted 580 kōans in his teachings. He compiled some 300 kōans in the volumes known as the Greater Shōbōgenzō. Dōgen wrote of Genjokōan, which points out that everyday life experience is the fundamental kōan.  However, according to Michel Mohr,

Sanbo Kyodan and White Plum Asanga.

The Sanbo Kyodan school and the White Plum Asanga, which originated with the Sōtō-priest Hakuun Yasutani, incorporates koan-study. The Sanbo kyodan places great emphasis on kensho, initial insight into one's true nature, as a start of real practice. It follows the so-called Harada-Yasutani koan-curriculum, which is derived from Hakuin's student Takuju. It is a shortened koan-curriculum, in which the so-called "capping phrases" are removed. The curriculum takes considerably less time to study than the Takuju-curriculum of Rinzai.  To attain kensho, most students are assigned the mu-koan. After breaking through, the student first studies twenty-two "in-house" koans, which are "unpublished and not for the general public", but are nevertheless published and commented upon. There-after, the students goes through the "Gateless Gate" (Mumonkan), the "Blue Cliff Record", the "Book of Equanimity", and the "Record of Transmitting the Light". The koan-curriculum is completed by the Five ranks of Tozan and the precepts.

Classical kōan collections.

Kōans collectively form a substantial body of literature studied by Zen practitioners and scholars worldwide. Kōan collections commonly referenced in English include: In these and subsequent collections, a terse "main case" of a kōan often accompanies prefatory remarks, poems, proverbs and other phrases, and further commentary about prior emendations.

The Blue Cliff Record.

The "Blue Cliff Record" (Chinese: Bìyán Lù; Japanese: Hekiganroku) is a collection of 100 kōans compiled in 1125 by Yuanwu Keqin ( 1063–1135).

The Book of Equanimity.

The "Book of Equanimity" or "Book of Serenity" (Chinese: Cóngróng lù; Japanese: Shōyōroku) is a collection of 100 Kōans by Hongzhi Zhengjue (Chinese: ; Japanese: Wanshi Shōgaku) (1091–1157), compiled with commentaries by Wansong Xingxiu (1166–1246). The full title is "The Record of the Temple of Equanimity With the Classic Odes of Venerable Tiantong Jue and the Responsive Commentary of Old Man Wansong" (Wansong Laoren Pingchang Tiantong Jue Heshang Songgu Congrong An Lu) (Taisho Tripitaka Vol. 48, No. 2004)

The Gateless Gate.

"The Gateless Gate" (Chinese: Wumenguan; Japanese: Mumonkan) is a collection of 48 kōans and commentaries published in 1228 by Chinese monk Wumen () (1183–1260). The title may be more accurately rendered as "Gateless Barrier" or "Gateless Checkpoint").  Five kōans in the collection derive from the sayings and doings of Zhaozhou Congshen, (transliterated as Chao-chou in Wade-Giles and pronounced Jōshū in Japanese).

Treasury of the True Dharma Eye.

Dahui Zonggao (大慧宗杲) (1089–1163) the "Zhengfayan zang" (正法眼藏), "Treasury of the true dharma eye" (W-G.: Cheng-fa yen-tsang, (J.: Shōbōgenzō) a collection of koans and dialogues compiled between 1147 and 1150 by Dahui Zonggao. Dahui's 'Treasury' is composed of three scrolls prefaced by three short introductory pieces. The Zongmen liandeng huiyao 宗門聯燈會要 was compiled in 1183 by Huiweng Wuming 晦翁悟明 (n.d.), three generations after Dahui in the same line; the sermon is found in zh 20 (x 79: 173a).  Other kōan collections compiled and annotated by Sōtō priests include:

Examples of traditional kōans.

The sound of one hand.

Victor Hori comments:

Original Face.

Huìnéng asked Hui Ming, "Without thinking of good or evil, show me your original face before your mother and father were born." (This is a fragment of case No. 23 of the "Wumenguan".)

A (;, ; "gong-an"; ) is a story, dialogue, question, or statement which is used in Zen practice to provoke the "great doubt" and to practice or test a student's progress in Zen.

Kóan (japonsky 公案) je krátký iracionální příběh obsahující nelogickou „hádanku“, která osvobozuje mysl od zavedených konceptů. Název pochází z nejznámější sbírky čínských zenových kóanů "Brána bez dveří", čínsky "Wumenguan" (無門關 [Wúménguān] (pchin-jin)/[Wu-men-kuan] (O. Švarný)), sinojaponsky "Mumonkan" (無門関 [Mumonkan]). Sbírka sestává ze čtyřiceti osmi „případů“ (původní význam čínského termínu "gong ́an", sinojaponského "kóan"; 公案) s autorovým často paradoxním nebo ironickým komentářem a závěrečným čtyřverším, gáthou. Autorem sbírky byl mnich a učitel Wumen Huikai (1183–1260).


Background.

The treaty was the result of long negotiations which began in Messina, Italy, on 2 June 1995, nearly forty years after the signing of the Treaty of Rome, and reached completion in Amsterdam on 18 June 1997. Following the formal signing of the Treaty on 2 October 1997, the Member States engaged in an equally long and complex ratification process. The European Parliament endorsed the treaty on 19 November 1997, and after two referendums and 13 decisions by parliaments, the Member States finally concluded the procedure.

Contents.

The treaty of Amsterdam comprises 13 Protocols, 51 Declarations adopted by the Conference, and 8 Declarations by Member States, plus amendments to the existing Treaties set out in 15 Articles. Article 1 (containing 16 paragraphs) amends the general provisions of the Treaty on European Union and covers the CFSP and cooperation in criminal and police matters. The next four Articles (70 paragraphs) amend the EC Treaty, the European Coal and Steel Community Treaty (which expired in 2002), the Euratom Treaty, and the Act concerning the election of the European Parliament. The final provisions contain four Articles. The new Treaty also set out to simplify the Community Treaties, deleting more than 56 obsolete articles and renumbering the rest in order to make the whole more legible. By way of example, Article 189b on the codecision procedure became Article 251.  The most pressing concerns of ordinary Europeans, such as their legal and personal security, immigration, and fraud prevention, were all dealt with in other chapters of the Treaty. In particular, the EU became responsible for legislating on immigration, civil law or civil procedure, insofar as this is necessary for the free movement of persons within the EU. At the same time, intergovernmental co-operation was intensified in the police and criminal justice field so that Member States should be able to coordinate their activities more effectively. The Union aims to establish an area of freedom, security and justice for its citizens. The Schengen Agreements have now been incorporated into the legal system of the EU (Ireland and the United Kingdom remained outside the Schengen agreement, see Common Travel Area for details).  The Treaty lays down new principles and responsibilities in the field of the common foreign and security policy, with the emphasis on projecting the EU's values to the outside world, protecting its interests, and reforming its modes of action. The European Council will lay down common strategies, which will then be put into effect by the Council acting by a qualified majority, subject to certain conditions. In other cases, some Member States may choose to abstain "constructively", i.e. without actually preventing actions being taken.  The treaty introduced a High Representative for EU Foreign Policy who, together with the Presidents of the Council and the European Commission, puts a "name and a face" on EU policy to the outside world. Although the Amsterdam Treaty did not provide for a common defence, it did increase the EU's responsibilities for peacekeeping and humanitarian work, in particular by forging closer links with Western European Union.  As for the institutions, there were two major reforms concerning the co-decision procedure (the legislative procedure involving the European Parliament and the Council), affecting its scope—most legislation was adopted by the co-decision procedure—and its detailed procedures, with Parliament playing a much stronger role. The President of the Commission will also have to earn the personal trust of Parliament, which will give him the authority to lay down the Commission's policy guidelines and play an active part in choosing the Members of the Commission by deciding on their appointment by common accord with the national governments. These provisions make the Commission more politically accountable, particularly vis-à-vis the European Parliament. Finally, the new Treaty enables, under very strict conditions, closer co-operation between Member States which so wish. Closer co-operation may be established, on a proposal from the Commission, in cases where it is not possible to take joint action, provided that such steps do not undermine the coherence of the EU or the rights and equality of its citizens.

Challenges.

The Amsterdam Treaty did not settle all institutional questions. Work was still in progress on reforming the institutions to make them capable of operating effectively and democratically in a much enlarged EU. The most pressing issues were the composition of the Commission and the weighting of Member States' votes upon qualified majority voting. These questions were addressed in the Treaty of Lisbon.

Signatures.

Withdrawal.

On 31 January 2020, the United Kingdom left the European Union and so withdrew from the treaty.

The Treaty of Amsterdam, officially the Treaty of Amsterdam amending the Treaty on European Union, the Treaties establishing the European Communities and certain related acts, was signed on 2 October 1997, and entered into force on 1 May 1999; it made substantial changes to the Treaty of Maastricht, which had been signed in 1992.

Amsterodamská smlouva, která byla podepsána 2. října 1997 a v platnost vstoupila 1. května 1999, změnila a přečíslovala Smlouvu o EU a Smlouvu o ES. Úplná znění těchto smluv jsou k ní připojena.


Outline.

The city's main street (Wakasa, or "young cherry blossom" street) runs north from the station and terminates at the foot of the Kyushouzan ("eternal pine") mountain. Around this mountain lies the oldest part of the city. Its centre is the now ruined Tottori Castle, once the property of the Ikeda clan daimyō who ruled the Tottori Domain during the Edo period. It is open to the public, and is the site of the Castle Festival in autumn each year. In the vicinity are temples, museums, and public parks. The city also hosts the prefecturally famous Shan-shan festival in the summer, which features teams of people dressing up and dancing with large umbrellas; the name 'Shan-shan' is said to come from the sound made by the small bells and pieces of metal attached to the umbrellas, which are very large. An exceptionally big example of a Shan-shan umbrella graces the main foyer of Tottori Station.  At the beginning of every summer, Tottori is host to one of the biggest beach parties in the country, the San In Beach Party. The event lasts an entire weekend and some top names on the national DJ circuit are invited to perform.

History.

Tottori was incorporated as a city on October 1, 1889. Most of the downtown area was destroyed by the Tottori earthquake of September 10, 1943, which killed over 1000 people.  The organization AFS (AFS Intercultural Programs) for exchange students is relatively developed in Tottori. Exchange students who come to Tottori can experience countryside life and enjoy traditional Japanese customs through the many events organized by the Tottori AFS.  Redistricting ("gappei") of the city's borders in November 2004 increased its size to include a number of surrounding areas. On November 1, 2004, the town of Kokufu, the village of Fukube (both from Iwami District), the towns of Aoya, Ketaka and Shikano (all from Ketaka District), the towns of Kawahara and Mochigase and the village of Saji (all from Yazu District) were merged into Tottori. Ketaka District was dissolved as a result of this merger.

Education.

Tottori City has two universities. The main campus of Tottori University, a national public university, is located next to Koyama Lake on the west end of the city. The privately funded Tottori University of Environmental Studies is located in the south-eastern part of Tottori city, near the town of Yazu. These two universities are not to be confused with the 2-year junior college in the prefecture, Tottori College, which is located in the central city of Kurayoshi.

Transportation.

In the city's downtown shopping district, Tottori Station offers regularly scheduled local and express train service on the JR West rail line. Travel time from Osaka is approximately 2 hours 30 minutes. Tottori City's local and inter-city Bus Terminal is also conveniently located next to Tottori Station. On the west end of the city, Tottori Airport provides daily scheduled flights to Tokyo's Haneda Airport.

Climate.

Tottori has a humid subtropical climate (Köppen climate classification "Cfa") with hot summers and cool winters. Precipitation is abundant throughout the year.

As of June 1, 2016, the city has an estimated population of 192,912 and a population density of 250 persons per km. The total area is 765.31 km.

Tottori (: 鳥取市; "Tottori-ši") je hlavní město prefektury Tottori v regionu Čúgoku v Japonsku. Město se rozkládá poblíž Japonského moře, ale neleží na pobřeží. Žije zde obyvatel. Tottori bylo založeno 1. října 1889.


Character.

Susan is the daughter of Ysabell, Death's adopted daughter, who is introduced in "The Light Fantastic", and Mort, who was briefly Death's apprentice in the book "Mort". At the end of "Mort" they leave Death's domain and become Duke and Duchess of Sto Helit, taking the motto "Non Temetis Messor": "Don't Fear the Reaper.") Susan is their only child.  Susan is introduced in "Soul Music" as a sixteen-year-old pupil at the Quirm College for Young Ladies, shortly after the deaths of her parents. Initially blaming Death for not saving them, she has come to accept that he is able only to grant them an eternal moment in his domain, which they have refused. After graduating — and despite being Duchess of Sto Helit — she begins a teaching career, first as a governess, in "Hogfather", and then as a schoolteacher, in "Thief of Time". She insists on being addressed as "Miss Susan".  In "Soul Music" Death takes a holiday from his work in an attempt to forget his more troubling memories, and a metaphysical vacancy is created. Susan is "sucked in", as Death's manservant Albert puts it, forcing her to assume the role. At first she desires to use her power to help humanity, but as the book progresses she comes to realise that she is powerless to interfere, and discovers the inevitability of death and destiny. She is released from the position following the return of her grandfather, who breaks the rules in order to save the rock star Imp Y Celyn and his band.  In "Hogfather" the Auditors employ Mr Teatime, an assassin who attempts to destroy the Hogfather using teeth found at the Tooth Fairy's castle to control children. Death cannot enter the Tooth Fairy's castle because it is constructed from the imaginations of children, who have no concept of death, and therefore arranges for Susan to foil their plan instead. After removing all of the Auditors' human agents from the Tooth Fairy's country, Susan saves the Hogfather from being destroyed by a group of Auditors who have taken the forms of dogs. She later kills Mr Teatime by impaling him with the poker she uses to threaten monsters.  In "Thief of Time" Susan once again comes into conflict with the Auditors, who are now attempting to stop time so that they can catch up with their paperwork. She is forced to find the son of Time, whom Death cannot influence or even see, because, being only "mostly human", the boy is not subject to death. Susan is aided in her mission by Lu-Tze, a philosopher/James Bond parody, and Myria LeJean/Unity, a former Auditor who becomes human. Time's husband, Wen the Eternally Surprised, describes her as "helpfulness personified".

Physical appearance.

Susan is a "slightly built young woman"; both Mustrum Ridcully and Terry Pratchett himself have described her as being "attractive in a skinny way". Her hair is pure white, but with a streak of black running through it from end to end. Although its natural state is a frizzy mass reminiscent of a dandelion, it rearranges its style of its own accord depending on Susan's mood; it tends to form a tight bun while she is working. Susan's hair is an inverted homage to Elsa Lanchester's appearance in "Bride of Frankenstein", in which she wore a black beehive wig with white streaks. In "The Art of Discworld", Paul Kidby draws Susan in Edwardian clothing, which he feels fits well with her job as a nanny in "Hogfather".  Susan has a very striking physical presence, which both Lu-Tze and Lobsang Ludd have remarked upon, and despite her relative youth, she projects a sense of great age. She possesses a birthmark on her cheek that shows itself only when she blushes; it consists of three finger-like lines that were left on her father when Death slapped him in "Mort", and which glow when she is angry. In "Soul Music", she complains that, as Death's granddaughter, she should have been born with better cheekbones. She also has a Look (always capitalised) which can be rather disconcerting, even to those in authority, such as her grandfather and the headmistress of the school in which she teaches. In the television special, her Look is shown as being able to turn her face into something rather similar to a skeleton's.

Powers and abilities.

Despite only being Death's "adoptive" granddaughter, Susan has inherited certain of his abilities: She can ""walk through walls and live outside time and be a little bit immortal"." As well as being able to find any living creature, Susan can sense whether or not an entity is human. She can understand the intentions of the Death of Rats even though she cannot directly interpret its speech, and has the ability to use her grandfather's voice to command or intimidate others. This speech is indicated, similar to Death's, ""; however, unlike those of her grandfather, the words which Susan speaks in this voice are often (if not always) enclosed within quotation marks, particularly in "Hogfather".  Susan has inherited Death's perfect memory, which includes the ability to ""remember the future"", and an instinctive knowledge of the nature of Death's work, which gives her considerable assistance during her brief time doing her grandfather's job in "Soul Music". In order to keep her from going insane, her mind represses much of the knowledge provided by this memory, but even so, parts of it occasionally permeate her consciousness, generally manifesting as premonitions or intuitive insights into forthcoming events. In "Hogfather", she states that the fragmented nature of such foresight makes the power largely unhelpful.  Like Death or experienced witches, Susan can make herself completely unnoticeable to ordinary people if she so chooses, though anyone who "can see what's really there", such as Albert or Mustrum Ridcully, who are used to such things, are still able to see her if they concentrate and she is not actively trying to avoid their specific notice. During her time at Quirm College, she unconsciously used this power to avoid being asked questions in subjects in which she had no interest, such as Literature and History. Unfortunately, this caused the teachers of these subjects to believe that Susan was not attending their classes, and she was reported to the headmistress on several occasions. She solved this problem by using her power to erase the headmistress' memory of her supposed misconduct.  She possesses a unique perspective on life, in that she lacks the normal human ability to ignore things which do not fit in with a logical world-view: in "Soul Music", she is able to acknowledge the enormous size of the rooms in Death's Domain, whereas most humans can only deal with the incomprehensible vastness by pretending it is not there; "Hogfather" reveals that she shares the ability of witches, wizards and young children to see things which are invisible to most people, such as the tooth fairy, monsters and bogeymen; in "Thief of Time", she is able to identify the historical anomalies created by the History Monks' reconstruction of the shattered timeline. The latter novel also reveals that Susan possesses a sort of hyperawareness of the world around her, in that she is ""aware of every step of the rocks beneath [her] feet and the stars overhead"."  On various occasions, unusual circumstances have rendered some or all of Susan's powers useless: In "Hogfather", she becomes completely human and finds herself bereft of her inherited gifts upon entering the Tooth Fairy's castle. This is because the laws of reality within the castle are based on the beliefs of children, which do not include a concept of death; hence the part of Susan which is derived from Death does not exist there. In "Thief of Time", Susan finds herself unable to walk through walls while time is being held in stasis. She speculates that the energy of the glass clock which is holding time static is in some way interfering with her power.  Due in part to her education at Quirm College for Young Ladies, Susan possesses various practical skills, some of which contribute to her success as a governess and later a teacher: she is accomplished in the fields of Mathematics and Logic (priding herself on her ability to mentally calculate the square root of 27.4), is multilingual, and has considerable knowledge of Discworld culture. She is also a competent swimmer, being versed in four swimming strokes and several lifesaving techniques.  Despite coming from a technically purely human background, Susan has inherited abilities from her adoptive Grandfather through more-than-conventional means: her mother, Ysabell, was merely adopted into Death's family; her father, Mort, merely married into Death's family; whereas Susan was conceived and born in Death's family. In the novels, it is said ""some things were inherited through more than genetics...some things were inherited through the soul...some things were in the bones"."

Personality and traits.

Susan's most obvious character trait is being sensible, an attribute carefully cultivated by her parents as a counterbalance to the influence of her grandfather. Initially, this manifested itself as a refusal to admit the supernatural side of the world (beyond basic magic) even existed. This is not surprising, given the fact that her parents had informed her from a very early age that there were no such things as the Soul Cake Duck, the Hogfather or the Tooth Fairy. It has even been suggested that her parents chose to name her Susan specifically because of the sensible and conventional connotations of the name. This upbringing has instilled in her a certain lack of romanticism; her personal appraisal of "a poem about daffodils" is, ""Apparently the poet had liked them very much."" She can be relied upon to keep her head in a crisis, something she tends to view as a character flaw.  Latterly, she accepts that she is part of the same world as the Hogfather and the Tooth Fairy—she just wishes she wasn't. Indeed, in "Hogfather", she is seen to be making an immense effort to remain 'normal', carefully limiting her use of her inherited powers and forcing herself to act in as 'human' a way as possible. She mentions having great difficulty in remembering things which other humans take for granted, such as the purpose of doorknobs, the way to fall asleep and how to forget things, but argues that, if she were to abandon this struggle, and give herself fully to her supernatural side, she would lose her humanity. In "Thief of Time", though still resentful of having been born Death's granddaughter and attempting to avoid too much contact with the supernatural world, she appears to have accepted and even embraced her heritage: she admits, albeit grudgingly, that she is not completely human, frequently uses her powers to provide teaching aids, and views herself as an exception to the rules of normal human society, as evidenced by her willingness to investigate the personal papers of her employer, Madame Frout, without her knowledge.  In following with her practical outlook on life, Susan does not have a great deal of patience with people who behave in an inefficient or unfocussed fashion. She also has a certain distrust for philosophy, disliking its attempts to oversimplify an inherently complicated world.  She appears to have a preference for the colour black, in that most of her childhood drawings were done in this colour (mentioned in "Soul Music"). This fixation is not as extreme as that which her mother possessed for the colour pink, and may in fact be a characteristic inherited from Death, who made most of the decorations for his Domain black. She has an intense fixation on chocolate (provided there is no nougat in it), one about which she is very defensive.  Another aspect of her personality which may stem from her relationship with Death is the fact that she is, by her own admission, "not very musical" (her grandfather also possessed a distinct lack of talent in the field of music, making several unsuccessful attempts to learn how to play the violin and the banjo). This may be the result of her aforementioned upbringing in which imagination and creativity were not encouraged to any degree, making it more of an environmentally instilled trait than an inherited one.  Susan has, on several occasions, demonstrated rather unusual attitudes toward school and education in general: In "Soul Music", she cites school as one of the greatest obstacles to education, and in "Hogfather", she compares being educated to having a communicable sexual disease, in that "It made you unsuitable for a lot of jobs and then you had the urge to pass it on".  She has expressed a fondness for children, as long as they are "not raw"; hopefully meaning that although the idea of having children herself does not appeal to her, she enjoys spending time with those of other people. She also demonstrates an insight into the more disturbing aspects of childhood nature, as she enjoys listening to the sound of children playing while she is reading, but always positions herself at such a distance that she is unable to hear what the children are saying, lest she find it unsettling. Because of this insight, she has a knack for putting problem children (such as those who try to get around her rules) in their place.

Teaching methods.

As the novels progress, Susan proves to be quite good at handling small children, a skill that is attributed to her sensible and practical nature. This is reflected in her novel approach to children's problems. When a child complains about a monster in the cupboard or under the bed, most parents would go to great lengths to carefully explain to the child that there is no monster. Susan, on the other hand, simply hands the child a suitable weapon with which to assault the monster, or, in the event of an "actual" monster, assaults it herself. Monsters from a wide area have come to dread the fireplace poker she uses for this task, although as word of Susan has quickly spread among the city's resident monsters, she lately has only needed to deal with newcomers. Her practical nature is quite similar to Granny Weatherwax's "headology", though the two are used in different fashions.  Her approach in other areas is also unusual. For example, in her role as a governess she has found that her charges' reading progress has been greatly enhanced by using interesting books which are slightly too difficult for them, and which therefore present something of a challenge. Parents have reservations about her choice of General Tacticus' "Campaigns" as a reader, since it may be argued that children under ten do not necessarily need to be able to spell 'disembowelled'. When other adults point out that children should find these exercises too advanced, Susan acknowledges this, but points out that she hasn't told the children this and so far they seem not to be bothered about it.  Using her powers as a teaching aid in her career as a schoolteacher, Susan is sufficiently successful as to have parents clamouring in large numbers to have their child included in her class. Her approach to history and geography, subjects which children often find rather dull, has particularly captured her class's attention. Parents generally see the occasional need to clean their children's clothing of dried-in bloodstains or ground-in swamp mud as more than compensated for by the broad education being received. A child's description of one of the classic battles from Ankh-Morpork's long history, for example, might be sufficiently vivid and detailed to make the parent think that the description could not have been improved upon if the child had actually seen the battle at first hand—which in fact he has, given the flexibility of time and space Susan has inherited from her grandfather.  Susan's role as a caregiver to children, combined with her no-nonsense style and almost magical flair for stick-like weaponry (e.g. her grandfather's scythe, field hockey sticks, a fireplace poker), can be seen as a parody of Mary Poppins. Mary Poppins also had a very similar attitude while actively encouraging positive imagination (Susan tends to say things like ""Real children don't go hoppity-skip unless they're on drugs""), took children on magical adventures (Susan does so to teach geography), introduced children to supernatural creatures (Susan employs such beings as guest speakers, including her own grandfather), and had a magic umbrella (which, while not used as a blunt object, was magical much like Death's scythe). Neither character openly acknowledges her magical powers. Both tend toward being actively insulted when reminded of their use. The link between Susan and Mary Poppins is explicitly alluded to in "Hogfather", when Susan states that ""She'd sworn that if she did indeed ever find herself dancing on rooftops with chimney sweeps, she'd beat herself to death with her own umbrella"."

Relationships.

In "The Art of Discworld", Pratchett describes Susan as "rather chilly", and Susan herself admits in "Thief of Time" that she finds it difficult to relate to other humans on a personal level because the supernatural parts of her mind tend to view mortal creatures as nothing more than "a temporary collection of atoms that [will] not be around in another few decades". She has yet to demonstrate much affection for others, though her relationship with her grandfather, once strained, improves over the course of the series. Despite this, she finds herself unable to trust him completely because of the way he occasionally manipulates her into helping him.

Romantic relationships.

Though Susan was previously infatuated with rocker Imp Y Celyn ("Soul Music"), "Thief of Time" ended with an unspecified "perfect moment" between Susan and Lobsang Ludd, the new anthropomorphic personification of Time. Though the moment itself was not described, Ludd caught her attention by levitating metallic silver and gold stars and setting them spinning about near the ceiling of the Stationery Cupboard, and dimming the lighting to velvety darkness, both rather romantic gestures. Also, Myria (later known as Unity) bluntly questioned Susan as to whether or not she had romantic intentions in regard to the boy, to which Susan responded with the defensive attitude she usually reserves for her fondness of chocolates.

Appearances in other media.

Television.

Animation.

In the Cosgrove Hall animation of "Soul Music", Susan was voiced by Debra Gillett.

Live action.

In the Sky One live-action adaptation of "Hogfather" the character was played by Michelle Dockery.

Computer games.

She appears as a young child in the computer game, "".

Susan Sto Helit (also spelled Sto-Helit), once referred to as Susan Death, is a fictional character in Terry Pratchett's "Discworld" series of fantasy novels. She is the adoptive granddaughter of Death, the Disc's Grim Reaper, and has a number of his abilities. She appears in three "Discworld" novels: "Soul Music", "Hogfather", and "Thief of Time". She is also referred to, though not by name, at the end of "Mort", when her father invites Death to her christening. Being both human and supernatural, Susan is frequently and reluctantly forced away from her normal life to do battle with malign supernatural forces or to take on her grandfather's job in his absence. Death tends to employ her in his battles against the Auditors of Reality, particularly in situations where he has no power or influence. As the series progresses, she also begins to take on roles educating children, so that, as Pratchett mentions in "The Art of Discworld", she has "ended up, via that unconscious evolution that dogs characters, a kind of Goth Mary Poppins".

Zuzana Stohelitská neboli vévodkyně Zuzana ze Sto Helit (také zvaná Smrt Zuzanka) je vnučkou jedné z nej(ne)populárnějších postav světa Zeměplochy (série knih Terry Pratchetta) vůbec – Smrtě.