7.E: Momenergy (Exercises)
PRACTICE
7-1 momenergy 4-vector
For each of the following cases, write down the four components of the momentum-energy (momenergy) 4-vector in the given frame in the form \(\left[E, p_{x}, p_{y}\right.\) , \(p_{z}\) ]. Assume that each particle has mass \(m\) . You may use square roots in your answer.
a A particle moves in the positive \(x\) -direction in the laboratory with total energy equal to five times its rest energy.
b Same particle as observed in a frame in which it is at rest.
c Another particle moves in the \(z\) -direction with momentum equal to three times its mass.
d Yet another particle moves in the negative \(y\) -direction with kinetic energy equal to four times its mass.
e Still another particle moves with total energy equal to ten times its mass and \(x-, y\) -, and \(z\) -components of momentum in the ratio 1 to 2 to \(3 .\)
7-2 system mass
Determine the mass of the system of particles shown in Figure 7-6. Is this system mass equal to the sum of the masses of the individual particles in the system? Does the mass of this system change as a result of the interaction? Does the momenergy 4-vector of the system change as a result of the interaction? (In Chapter 8 there is a lot more discussion about the mass of a system of particles.)
7-3 much ado about little
Two freight trains, each of mass \(5 \times 10^{6}\) kilograms (5000 metric tons) travel in opposite directions on the same track with equal speeds of 42 meters/second (about 100 miles/hour). They collide head on and come to rest.
a Calculate in milligrams the kinetic energy for each train \((1 / 2) m v^{2}\) before the collision. (Newtonian expression OK for \(100 \mathrm{mph} !\) ) ( 1 milligram \(=10^{-3}\) gram \(=10^{-6}\) kilogram)
b After the collision, the mass of the trains plus the mass of the track plus the mass of the roadbed has increased by what number of milligrams? Neglect energy lost in the forms of sound and light.
7-4 fast protons
Each of the protons described in the table emits a flash of light every meter of its own (proper) time \(d \tau\) . Between successive flash emissions, each proton travels a distance given in the left column. Complete the table. Take the rest energy of the proton to be equal to \(1 \mathrm{GeV}=10^{9} \mathrm{eV}\) and express momentum in the same units. Hints: Avoid calculating or using the speed \(v\) in relativistic particle problems; it is too close to unity to distinguish between protons of radically different energies. An accuracy of two significant figures is fine; don’t give more. Recall: \(E^{2}-p^{2}=m^{2}\) and \(E=m d t / d \tau=m \gamma\) [note tau!].
|
Lab distance \(\Delta x\)traveled between flashes (meters) |
Momentum \ (m d x/ d\tau\)
|
Energy
|
Time stretch
|
Lab time
|
|---|---|---|---|---|
| 0 | ||||
| \(0.1\) | ||||
| 1 | ||||
| 10 | ||||
| \(10^{3}\) | ||||
| \(10^{6}\) | ||||
| factor \(\gamma\) |
PROBLEMS
7-5 Lorenfz fransformation for momenergy componenfs
The rocket observer measures energy and momentum components of a particle to have the values \(E^{\prime}\) and \(p_{x}{ }^{\prime}\) , \(p_{y}^{\prime}\) , and \(p_{z}^{\prime}\) . What are the corresponding values of energy and momentum measured by the laboratory observer? The answer comes from the Lorentz transformation, equation (L-10) in the Special Topic following Chapter 3 .
The moving particle emits a pair of sparks closely spaced in time as measured on its wristwatch. The rocket latticework of clocks records these emission events; so does the laboratory latticework of clocks. The rocket observer constructs components of particle momentum and energy, equation \((7-2)\) , from knowledge of particle mass \(m\) , the spacetime displacements \(d t^{\prime}, d x^{\prime}, d y^{\prime}\) , and \(d z^{\prime}\) derived from the event recordings, and the proper time \(d \tau\) computed from these spacetime components. Laboratory momenergy components come from transforming the spacetime displacements. The Lorentz transformation, equation (L-10), for incremental displacements gives
\[\begin{aligned} d t &=v \gamma d x^{\prime}+\gamma d t^{\prime} \\ d x &=\gamma d x^{\prime}+v \gamma d t^{\prime} \\ d y &=d y^{\prime} \\ d z &=d z^{\prime} \end{aligned}\]
a Multiply both sides of each equation by the invariant mass \(m\) and divide through by the invariant proper time \(d \tau\) . Recognizing the components of the momenergy 4-vector in equation (7-2), show that the transformation equations for momenergy are
\[\begin{aligned} &E=v \gamma p^{\prime}{ }_{x}+\gamma E^{\prime} \\ &p_{x}=\gamma p^{\prime}{ }_{x}+v \gamma E^{\prime} \\ &p_{y}=p^{\prime}{ }_{y} \\ &p_{z}=p_{z}^{\prime} \end{aligned}\]
\(\mathbf{b}\) Repeat the process for particle displacements \(d t, d x, d y\) , and \(d z\) recorded in the laboratory frame to derive the inverse transformations from laboratory to rocket.
\[\begin{aligned} &E^{\prime}=-v \gamma p_{x}+\gamma E \\ &p_{x_{x}}^{\prime}=\gamma p_{x}-v \gamma E \\ &p^{\prime}{ }^{\prime}=p_{y} \\ &p_{z}^{\prime}=p_{z} \end{aligned}\]
7-6 fast electrons
The Two-Mile Stanford Linear Accelerator accelerates electrons to a final kinetic energy of \(47 \mathrm{GeV}(47 \times\) \(10^{9}\) electron-volts; one electron-volt \(=1.6 \times 10^{-19}\) joule). The resulting high-energy electrons are used for experiments with elementary particles. Electromagnetic waves produced in large vacuum tubes ("klystron tubes") accelerate the electrons along a straight pipelike structure 10,000 feet long (approximately 3000 meters long). Take the rest energy of an electron to be \(m \approx 0.5 \mathrm{MeV}=0.5 \times 10^{6}\) electronvolts.
a Electrons increase their kinetic energy by approximately equal amounts for every meter traveled along the accelerator pipe as observed in the laboratory frame. What is this energy gain in \(\mathrm{MeV} /\) meter? Suppose the Newtonian expression for kinetic energy were correct. In this case how far would the electron travel along the accelerator before its speed were equal to the speed of light?
b In reality, of course, even the 47-GeV electrons that emerge from the end of the accelerator have a speed \(v\) that is less than the speed of light. What is the value of the difference \((1-v)\) between the speed of light and the speed of these electrons as measured in the laboratory frame? [Hint: For \(v\) very near the value unity, \(\left.1-v^{2}=(1+v)(1-v) \approx 2(1-v) .\right]\) Let a 47-GeV electron from this accelerator race a flash of light along an evacuated tube straight through Earth from one side to the other (Earth diameter 12,740 kilometers). How far ahead of the electron is the light flash at the end of this race? Express your answer in millimeters.
c How long is the " 3000 -meter’ accelerator tube as recorded on the latticework of rocket clocks moving along with a \(47-\mathrm{GeV}\) electron emerging from the accelerator?
7-7 super cosmic rays
The Haverah Park extensive air shower array near Leeds, England, detects the energy of individual cosmic ray particles indirectly by the resulting shower of particles this cosmic ray creates in the atmosphere. Between 1968 and 1987 the Haverah Park array detected more than 25,000 cosmic rays with energies greater than \(4 \times 10^{17}\) electron-volts, including 5 with an energy of approximately \(10^{20}\) electron-volts. (rest energy of the proton \(\approx 10^{9}\) electron-volts \(=\) \(1.6 \times 10^{-10}\) joule)
a Suppose a cosmic ray is a proton of energy \(10^{20}\) electron-volts. How long would it take this proton to cross our galaxy as measured on the proton’s wristwatch? The diameter of our galaxy is approximately \(10^{5}\) light-years. How many centuries would take as observed in our Earth-linked frame?
b The research workers at Haverah Park find no evidence of an upper limit to cosmic ray energies. A proton must have an energy of how many times its rest energy for the diameter of our galaxy to appear to it Lorentz-contracted to the diameter of the proton (about 1 femtometer, which is equal to \(10^{-15}\) meters)? How many metric tons of mass would have to be converted to energy with 100-percent efficiency equals 1000 kilograms.
Reference: M. A. Lawrence, R. J. O. Reid, and A. A. Watson, Journal of Physics G: Nuclear and Particle Physics, Volume 17, pages \(733-757\) (1991).
7-8 rocket nucleus
A radioactive decay or "inverse collision" is observed in the laboratory frame, as shown in the figure.
Suppose that \(m_{A}=20\) units, \(m_{C}=2\) units, and \(E_{C}=5\) units.
a What is the total energy \(E_{A}\) of particle \(A\) ?
b From the conservation of energy, find the total energy \(E_{D}\) (rest plus kinetic) of particle \(D\) .
c Using the expression \(E^{2}-p^{2}=m^{2}\) find the momentum \(p_{C}\) of particle \(C\) .
d From the conservation of momentum \(p_{D}\) of particle \(D\)
e What is the mass \(m_{D}\) of particle \(D\) ?
f Does \(m_{C}+m_{D}\) after the collision equal \(m_{A}\) before the collision? Explain your answer.
\(\mathbf{9}\) Draw three momenergy diagrams for this reaction similar to those of Figure 7-6: BEFORE, SYSTEM, and AFTER. Plot positive and negative momentum along the positive and negative horizontal direction, respectively, and energy along the vertical direction. On the AFTER diagram draw the momenergy vectors for particles \(C\) and \(D\) head to tail so that they add up to the momenergy vector for the system. Place labeled mass handles on the arrows in all three diagrams, including the arrow for the system.
7-9 sticky collision
An inelastic collision is observed in the laboratory frame, as shown in the figure. Suppose that \(m_{A}=2\) units, \(E_{A}=6\) units, \(m_{C}=15\) units.
a From the conservation of energy, what is the energy \(E_{B}\) of particle \(B\) ?
\(\mathbf{b}\) What is the momentum \(p_{A}\) of particle \(A\) ? Therefore what is the momentum \(p_{B}\) of particle \(B\) ?
c From \(m^{2}=E^{2}-p^{2}\) find the mass \(m_{B}\) of par-
d Quick guess: Is the mass of particle \(C\) after the collision less than or greater than the sum of the masses of particles \(A\) and \(B\) before the collision? Validate your guess from the answer to part \(\mathbf{c}\) .
7-10 colliding putty balls
A ball of putty of mass \(m\) and kinetic energy \(K\) streaks across the frozen ice of a pond and hits a second identical ball of putty initially at rest on the ice. The two stick together and skitter onward as one unit. Referring to the figure, find the mass of the combined particle using parts a-e or some other method.
a What is the total energy of the system before the collision? Keep the kinetic energy \(K\) explicitly, and don’t forget the rest energies of both particles \(A\) and \(B\) . Therefore what is the total energy \(E_{C}\) of particle \(C\) after the collision?
b Using the equation \(m^{2}=E^{2}-p^{2}=(m+\) \(K)^{2}-p^{2}\) find the momentum \(p_{A}\) of particle \(A\) before the collision. What is the total momentum of the system before the collision? Therefore what is the momentum \(p_{C}\) of particle \(C\) after the collision?
EXERCISE 7-10. Two putty balls stick together. c Again use the equation \(m^{2}=E^{2}-p^{2}\) to find the mass \(m_{C}\) of particle \(C\) . Show that the result satisfies the equation
\[m_{C}^{2}=(2 m)^{2}+2 m K=(2 m)^{2}\left(1+\frac{K}{2 m}\right)\]
d Examine the result of part \(c\) in two limiting cases. (1) The value of \(m_{C}\) in the Newtonian low-velocity limit in which kinetic energy is very much less than mass: \(K / m<<1\) . Is this what one expects from everyday living? (2) What is the value of \(m_{C}\) in the highly relativistic limit in which \(K / m>>1\) ? What is the upper limit on the value of \(m_{C}\) ? Discussion: Submicroscopic particles moving at extreme relativistic speeds rarely stick together when they collide. Rather, their collision often leads to creation of additional particles. See Chapter 8 for examples.
e Discussion question: Are the results of part c changed if the resulting blob of putty rotates, whirling like a dumbbell about its center as it skitters along?
7-11 limits of Newtonian mechanics
a One electron-volt \((\mathrm{eV})\) is equal to the increase of kinetic energy that a singly charged particle experiences when accelerated through a potential difference of one volt. One electron-volt is equal to \(1.60 X\) \(10^{-19}\) joules. Verify the rest energies of the electron and the proton (masses listed inside the back cover) in units of million electron-volts ( \(\mathrm{MeV}\) ).
\(\mathbf{b}\) The kinetic energy of a particle of a given velocity \(v\) is not correctly given by the expression \(1 / 2 m v^{2}\) . The error
is one percent when the Newtonian kinetic energy has risen to a certain fraction of the rest energy. What fraction? Hint: Apply the first three terms of the binomial expansion
\[(1+z)^{n}=1+n z+\frac{1}{2} n(n-1) z^{2}+\ldots\]
to the relativistic expression for kinetic energy, an accurate enough approximation if \(|z|<<1\) . Let this point - where the error is one percent - be arbitrarily called the "limit of Newtonian mechanics." What is the speed of the particle at this limit? At what kinetic energy does a proton reach this limit (energy in \(\mathrm{MeV}\) ? An electron?
c An electron in a modern color television tube is accelerated through a voltage as great as 25,000 volts and then directed by a magnetic field to a particular pixel of luminescent material on the inner face of the tube. Must the designer of color television tubes use special relativity in predicting the trajectories of these electrons?
7-12 derivation of the relativistic expression for momentum - a worked example
A very fast particle interacts with a very slow particle. If the collision is a glancing one, the slow particle may move as slowly after the collision as before. Reckon the momentum of the slow-moving particle using the Newtonian expression. Now demand that momentum be conserved in the collision. From this derive the relativistic expression for momentum of the fastmoving particle.
The top figure shows such a glancing collision. After the collision each particle has the same speed as before the collision, but each particle has changed its direction of motion.
Behind this figure is a story. Ten million years ago, and in another galaxy nearly ten million light-years distant, a supernova explosion launched a proton toward Earth. The energy of this proton far exceeded anything we can give to protons in our earthbound particle accelerators. Indeed, the speed of the proton so nearly approached that of light that the proton’s wristwatch read a time lapse of only one second between launch and arrival at Earth.
We on Earth pay no attention to the proton’s wristwatch. For our latticework of Earth-linked observers, ages have passed since the proton was launched. Today our remote outposts warn us that the streaking proton approaches Earth. Exactly one second on our clocks before the proton is due to arrive, we launch our own proton at the slow speed one meter/second almost perpendicular to the direction of the incoming proton (BEFORE part of the top figure). Our proton saunters the one meter to the impact point. The two protons meet. So perfect is our aim and timing that after the encounter our proton simply reverses direction and returns with the same speed we gave it originally (AFTER part of the top figure). The incoming proton also does not change speed, but it is deflected upward at the same angle at which it was originally slanting downward.
How much does \(y\) -momentum of our slow-moving proton change during this encounter? Newton can tell us. At a particle speed of one meter/second, his expression for momentum, \(m v\) , is accurate. Our proton simply reverses its direction. Therefore the change in its momentum is just \(2 m v\) , twice its original momentum in the \(y\) -direction.
What is the change in the \(y\) -momentum of the incoming proton, moving at extreme relativistic speed? We demand that the change in \(y\) -momentum of the fast proton be equal in magnitude and opposite in direction to the change in \(y\) -momentum of our slow proton. In brief, \(y\) -momentum is conserved. This demand, plus a symmetry argument, leads to the relativistic expression for momentum.
Key events in our story are numbered in the center figure. Event 1 is the launching of the proton from the supernova ten million years (in our frame) before the impact. Event 2 is the quiet launch of our local proton one second (in our frame) before the impact. Event 0 is the impact itself. The \(x\) -direction is chosen so that \(y\) -displacements of both protons have equal magnitude between launch and impact, namely one meter.
Now view the same events from a rocket moving along the \(x\) -axis at such a speed that events 1 and 0 are vertically above one another (bottom figure). For the rocket observer the transverse \(y\) -separations are the same as for the Earth observer (Section 3.6), so \(y=1\) meter in both frames. The order of events 1 and 2 , however, is exactly reversed in time: For the rocket observer, we released our proton at high speed ten million years before impact and she releases hers one second before the collision. Otherwise the diagrams are symmetrical: To make the bottom figure look like the center one, exchange event numbers 1 and 2 , then stand on your head!
Rocket observer and Earth observer do not agree on the time between events 1 and 0 , but they agree on the proper time \(\tau_{10}\) between them, namely one second. They also agree on the proper time \(\tau_{20}\) between events 2 and 0 . Moreover, because of the symmetry between the center and bottom figures, these two proper times have the same value: For the case we have chosen, the wristwatch (proper) time for each proton is one second between launch and impact.
\[\tau_{10}=\tau_{20}\]
We can use these quantities to construct expressions for the \(y\) -momenta of the two protons. Both are protons, so their masses \(m\) are the same and have the same invariant value for both observers. Because of the equality in magnitude of the \(y\) -displacements and the equality of \(\tau_{20}\) and \(\tau_{10}\) , we can write
\[m \frac{y}{\tau_{10}}=-m \frac{y}{\tau_{20}}\]
[both frames]
The final key idea in the derivation of the relativistic expression for momentum is that the slow-moving proton travels between events 2 and 0 in an Earthmeasured time that is very close in value to the proper time between these events. The vertical separation \(y\) between events 2 and 0 is quite small: one meter. In the same units, the time between them has a large value in the Earth frame: one second, or 300 million meters of light-travel time. Therefore, for such a slow-moving proton, the proper time \(\tau_{20}\) between events 2 and 0 is very close to the Earth time \(t_{20}\) between these events:
\[\tau_{20} \approx t_{20} \quad \text { [Earth frame only] }\]
Hence rewrite the both-frames equation for the Earth frame:
\[m \frac{y}{\tau_{10}}=-m \frac{y}{t_{20}} \quad \text { [Earth frame only] }\]
The right side of this equation gives the \(y\) -momentum of the slow proton before the collision, correctly calculated using the Newtonian formula. The change in momentum of the slow proton during the collision is twice this magnitude. Now look at the left side. We claim that the expression on the left side is the \(y\) -momentum of the very fast proton. The \(y\) -momentum of the fast proton also reverses in the collision, so the change is just twice the value of the left side. In brief, this equation embodies the conservation of the \(y\) component of total momentum in the collision. Con- clusion: The left side of this equation yields the relativistic expression for \(y\) -momentum: mass times displacement divided by proper time for this displacement.
What would be wrong with using the Newtonian expression for momentum on the left side as well as on the right? That would mean using earth time \(t_{10}\) instead of proper time \(\tau_{10}\) in the denominator of the left side. But \(t_{10}\) is the time it took the fast proton to reach Earth from the distant galaxy as recorded in the Earth frame - ten million years or 320 million million seconds! With this substitution, the equation would no longer be an equality; the left side would be 320 million million times smaller in value than the right side (smaller because \(t_{10}\) would appear in the denominator). Nothing shows more dramatically than this the radical difference between Newtonian and relativistic expressions for momentum - and the correctness of the relativistic expression that has proper time in the denominator.
This derivation of the relativistic expression for momentum deals only with its \(y\) -component. But the choice of \(y\) -direction is arbitrary. We could have interchanged \(y\) and \(x\) axes. Also the expression has been derived for particles moving with constant velocity before and after the collision. When velocity varies with time, the momentum is better expressed in terms of incremental changes in space and time. For a particle displacement \(d r\) between two events a proper time \(d \tau\) apart, the expression for the magnitude of the momentum is
\[p=m \frac{d r}{d \tau}\]
One-sentence summary: In order to preserve conservation of momentum for relativistic collisions, simply replace Newton’s "universal time" \(t\) in the expression for momentum with Einstein’s invariant proper time \(\tau\) .


40.2.1: Flowering
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The flowering plants (angiosperms) go through a phase of vegetative growth producing more stems and leaves and a flowering phase where they produce the organs for sexual reproduction. In " annuals ", like the snapdragon, the vegetative phase begins with germination of the seed. Flowering follows and ends with the senescence and death of the plant. In biennials , the vegetative phase takes up the first year; flowering followed by death occurs the second year. In perennials , flowering typically occurs year after year when conditions are appropriate.
Vegetative growth of the above-ground part of the plant — the shoot — occurs at the apical meristem . This is a mass of undifferentiated cells at the tip of the stem. Mitosis of these cells produces cells that differentiate to form more stem, leaves and secondary meristems . Also called lateral buds , these form in the axils of the leaves and will form branches.
The Signal to Flower
Flowering involves the conversion of the apical meristem into a floral meristem , from which all the parts of the flower will be produced. Signals that change the fate of the apical meristem include:
- maturity of the plant
- temperature
- the arrival of the plant hormone gibberellin
- for many plants, photoperiod - the relative length of day and night.
Temperature
Many annual plants (e.g., winter wheat) and biennial plants have their time of flowering delayed unless they have undergone a preceding period of wintertime cold. The change brought about by this prolonged exposure to the cold is called vernalization .
In the "model" plant Arabidopsis thaliana , vernalization works like this.
- A gene designated Flowering Locus C ( FLC ) encodes a transcription factor that blocks the expression of the genes needed for flowering.
- The level of FLC mRNA is high in the fall.
- But with the onset of cold temperatures, production of an antisense transcript of FLC (called COOLAIR ) increasesas does, later, a sense transcript of part of the FLC gene.
- Both of these RNAs are non-coding; that is, they are not translated into protein.
- But they cooperate in suppressing the production of FLC mRNA and its translation into FLC protein.
- With the arrival of spring, there is no FLC protein remaining to suppress flowering so flowering can begin.
The buds of many species of woody angiosperms found in temperate climates, such as apples and lilacs, also need a preceding period of cold weather before they can develop into flowers. So these plants cannot be grown successfully at lower latitudes because the winters never get cold enough (a few days at 0–10°C). This bud dormancy is localized. Prior chilling of one bud on a lilac stem enables it to flower while the other, nonchilled, buds on the stem remain dormant.
Photoperiod
Photoperiod is detected in the leaves. The cocklebur, drawn here, needs at least 8.5 hours of darkness in order to flower. Even if only a part of one leaf is exposed to the correct photoperiod, the entire plant will bloom (middle figure).
The leaves produce a chemical signal called florigen that is transmitted to the apical meristems to start their conversion into floral meristems. The right-hand drawing shows that grafting a cocklebur ( B ) that receives the required period of darkness to one ( A ) that does not causes flowering in both. Evidently the florigen signal passes from B to A through their connected vascular systems.
The chemical nature of florigen has been sought for decades. The most recent evidence suggests that at least one component is the protein encoded by the gene FLOWERING LOCUS T ( FT ).
Converting the Apical Meristem to a Floral Meristem
In the nucleus of the meristem cells, the FT protein binds to the transcription factor FD and turns on the expression of genes needed for flowering, e.g., APETALA1 and LEAFY .
Structure of the Flower
The floral meristem differentiates into four concentric groups of cells that form the four parts of the flower.
- The cells in whorl 1 develop into a whorl of sepals . These form at the lowest level. Collectively they make up the calyx .
- Whorl 2 forms above the calyx, forming the petals . Collectively these make up the corolla of the flower (the part that most ornamentals are grown for).
- Whorl 3 develops into the stamens , the male reproductive organs.
- The innermost whorl, 4 , forms carpels , the female reproductive organs. Carpels often fuse to form a single structure, which some botanists call the pistil .
What triggers the various parts of the floral meristem to enter one or another of these four developmental pathways?
The ABC Model of Flower Development
Genetic analysis of mutants especially those found in the dicots Arabidopsis thaliana and in the snapdragon ( Antirrhinum ) support the ABC model of flowering. This model postulates a group of genes that encode the transcription factors needed to turn on the genes for sepal, petal, etc. development. The "master switches" fall into 3 groups: A , B , and C .
These are the rules:
- Cells in which only A genes are expressed develop into sepals . This occurs at the lowest level of the floral meristem.
- Cells in which both A and B genes are expressed develop into petals . This occurs at the next higher level.
- Expression of B and C genes turns on the developmental program to form stamens .
- Expression of C genes alone turns on the development of carpels in the innermost band of cells.
Examples of A, B and C group genes involved in flowering - these have been identified in Arabidopsis thaliana
| A group |
APETALA1
(
AP1
) and
APETALA2 ( AP2 ) |
| B group |
APETALA3
(
AP3
) and
PISTILLATA ( PI ) |
| C group | AGAMOUS ( AG ) |
The transcription factor LEAFY plays a major role in turning on the A, B, and C group genes in the appropriate locations.
- The LEAFY protein alone turns on AP1 in whorls 1 and 2 .
- LEAFY plus a protein encoded by the gene UFO (for "unusual floral organs") turn on AP3 in whorls 2 and 3 .
- LEAFY and a second, still unidentified, protein turn on AG in whorls 3 and 4 .
If LEAFY protein alone is sufficient to turn on AP1 , why isn't AP1 expressed in all four whorls?
The answer: AGAMOUS blocks the expression of AP1 , so any cell expressing AGAMOUS cannot express AP1. In fact, the antagonism is reciprocal: AP2 in whorls 1 and 2 (A group) inhibits AGAMOUS so the gene expression in whorls 3 and 4 remains distinct from that in whorls 1 and 2.
The proteins encoded by APETALA3 and PISTILLATA (Group B) form a heterodimer that binds to
- the APETALA1 protein to form petals
- the AGAMOUS protein to form stamens
Aided by a fourth transcription factor encoded by the gene SEPALLATA3 , these quaternary complexes bind to specific sequences of DNA turning on the expression of the various genes needed to form whorls 2 and 3. Further research may reveal similar behavior for the other genes.
SEPALLATA3 ( SEP3 ) is one of four SEP genes in Arabidopsis. If all but SEP4 are inactivated, a flower with only sepals is formed (hence the name). If all four are inactivated, no flowers are formed at all.
So formation of a flower requires a cascade of sequential gene activity that gradually converts a mass of undifferentiated cells (the apical meristem) into the parts of a flower. The genes encode transcription factors that act as master switches, turning on (or off) downstream genes that ultimately make each part of the flower in its appropriate location. This same strategy of genetic control of developmental pathways is seen in animal development.


Work and Heat
Skills to Develop
- Compare and contrast work and heat
In physics, work is defined as motion over some distance against an opposing force. (A force is an acceleration multiplied by a mass.) For instance, lifting an object against the force of gravity. The amount of work is the opposing force multiplied by the distance the object moved. The amount of work done in lifting an object is the force of gravity (the mass of the object times the acceleration of gravity) times the height you lifted it. There are lots of other ways systems can do work: a stretched spring can expand and lift a weight, a battery or burning gas can drive a motor and move a car up hill or forward against friction and wind.
In chemistry, work is often defined in terms of a change in volume against a pressure. (Pressure is force divided by area, so convince yourself that P x V has the same units as F x d.) For instance, atmospheric pressure is constant at ~1 atm. If you have a sample of gas at higher pressure, and you let it come to mechanical equilibrium with the atmosphere, it will expand to some new volume. The work it does expanding against atmospheric pressure is (1 atm)(ΔV), where ΔV is (final volume - initial volume). In general, the work done by gases expanding is called pV work, and is
\[w=\int{pdV}\]
For our purposes, we won't be dealing with integrals, so we won't calculate work this way unless the pressure is constant, in which case we can use the simpler equation
\[w=-P\Delta V\]
where P is the constant pressure and ΔV is the change in volume of the system. The negative sign accounts for the fact that if the system is compressed, ΔV is negative, and work was done to the system, so w is positive.
There are several different definitions of heat. For instance, we can heat water to make tea, or enjoy the heat when we enter a warm room in the winter. In thermodynamics the meaning of heat is more precise: it is a process, a way energy can move. Heat is energy that moves from a hot object to a cold object. When heat leaves the system, it has a negative sign, and when it enters the system, it has a positive sign.
Heat and work are the ways that energy can move between objects. When you think about the molecules, the difference between work and heat is very simple. Work involves an orderly motion of molecules, like all the molecules in an object moving the same direction. Heat involves disorderly or random motions of molecules.


12.3: The Ming Dynasty
Painting under the Ming Dynasty
During the Ming Dynasty, Chinese painting developed from the achievements of the earlier Song and Yuan Dynasties.
Identify the time period and innovations of the Zhe, Yuanti, Wu, Wongjang, and Huating Schools of painting during the Ming dynasty
Key Points
- Compared to earlier styles , the Ming Dynasty saw the use of more colors, the development of new painting skills and techniques, and the advancement of calligraphy within paintings.
- The first dominant Ming style was called the Zhe School ; however, later conditions led to the rise of the Wu School, a somewhat subversive style that revived the ideal of the inspired scholar-painters in Ming China.
- The Zhe School and Yuanti School began to prosper during the early Ming period, while the painting schools of the Yuan dynasty began to decline.
- Both the Zhe and Yuanti Schools declined during the mid-Ming period while the Wu School prospered, inheriting and further developing the Yuan scholar-artist style of painting.
- The Wu School painters Tang Yin, Wen Zhengming, Shen Zhou, and Qiu Ying were regarded as the “Four Masters” of the Ming period.
- The late Ming period witnessed the rise of the Songjiang School and Huating School, both of which contributed to the development of the Shanghai School in the late 19th century.
Key Terms
- Songjiang School : A school during the late Ming Dynasty that rivaled Wumen, particularly in generating new theories of painting.
- Yuanti School : A school that was organized and supported by the Ming central government, and served for Ming royal court.
- Zhe School : A school of painters that was part of the Southern School, which thrived during the Ming Dynasty and was known for its formal, academic, and conservative outlook.
Background: The Ming Dynasty
Under the Yuan Dynasty (1279–1368), painters had practiced with relative freedom, cultivating a more “individualist” and innovative approach to art that deviated noticeably from the more superficial style of the Song masters who preceded them. However, at the outset of the Ming Dynasty (1368–1644), the Hongwu emperor (1368–1398) decided to import the existing master painters to his court in Nanjing, where he had the ability to cultivate their styles to conform to the paintings of the Song masters. Hongwu was notorious for his attempts to marginalize and persecute the scholar class, and this was seen as an attempt to banish the gentry’s influence from the arts.
The dominant style of the Ming court painters was called the Zhe School. However, following the ascension of the Yongle emperor (1403–1424), the capital was moved from Nanjing to Beijing, putting a large distance between imperial influence and the city of Suzhou. These new conditions led to the rise of the Wu School of painting, a somewhat subversive style that revived the ideal of the inspired scholar-painters in Ming China.
Painting Styles
During the Ming Dynasty, Chinese painting developed greatly from the achievements of the earlier Song Dynasty and Yuan Dynasty. The painting techniques that were invented and developed before the Ming period became classical during this period. More colors were used in painting during the Ming Dynasty; seal brown, for example, became much more widely used, and sometimes even over-used. Many new painting skills and techniques were innovated and developed, and calligraphy was much more closely and perfectly combined with the art of painting. Chinese painting reached another climax in the mid- to late-Ming Dynasty, when many new schools were born and many outstanding masters emerged.
Development
Early Ming Period (1368–1505)
The painting schools of the Yuan Dynasty still heavily influenced early Ming painting, but new schools of painting were also growing. In particular, the Zhe School and the Yuanti School were the dominant schools during the early Ming period. The painters of the Zhe School did not formulate a new distinctive style, preferring instead to further the style of the Southern Song and specializing in large and decorative paintings, most often of landscapes. The school was identified by a formal, academic, and conservative outlook. The Yuanti School was organized and supported by the Ming central government to serve the Ming royal court. Both of these new schools were heavily influenced by the traditions of both the Southern Song painting academy and the Yuan scholar-artists.
Middle Ming Period (1465–1566)
The classical Zhe School and Yuanti School began to decline during the mid-Ming period. Meanwhile, the Wu School (sometimes referred to as Wumen) became the most dominant school nationwide. Its formation is credited to painter Shen Zhou, who is known for using brushstrokes in the tradition of Yuan Dynasty masters. Suzhou, the activity center for Wu School painters, became the biggest center for Chinese painting during this period. The Wumen painters mainly inherited the Yuan scholar-artist style of painting and further developed this style into its peak. The painters Tang Yin, Wen Zhengming, Shen Zhou, and Qiu Ying were regarded as the “Four Masters” of the Ming period.
Often classified as Literati , scholars, or amateur painters (as opposed to professionals), members of the Wu School idealized the concepts of personalizing works and integrating the artists into the art. A Wu School painting is characterized by inscriptions describing the painting, the date, method, and/or reason for the work, which is usually seen as a vehicle for personal expression.
Late Ming Period (1567–1644)
The Songjiang School and Huating School were born and developed toward the end of the Ming Dynasty. The Songjiang School grew to rival the Wu School, particularly in generating new theories of painting. Both the Songjiang and Huating Schools formed the basis for the later Shanghai School in the late 19th century.
The Decorative Arts under the Ming Dynasty
As with many art forms, the Ming Dynasty saw advancement in the realm of decorative arts such as porcelain and lacquerware.
Discuss the advancements in Chinese porcelain during the Ming dynasty
Key Points
- In Ming China, carved designs in lacquerwares and designs glazed onto porcelain wares displayed intricate scenes similar in complexity to those in painting.
- Elaborate decorative items could be found in the homes of the wealthy alongside embroidered silks, rosewood furniture, feathery latticework, and wares of jade , ivory , and cloisonné. The major production centers for porcelain items in the Ming Dynasty were Jingdezhen in the Jiangxi province and Dehua in the Fujian province.
- The Dehua porcelain factories catered to European tastes by creating Chinese export porcelain by the 16th century.
- Connoisseurship in the late Ming period centered around these items of refined artistic taste, which provided work for art dealers and even underground scam artists who made fake imitations of originals.
Key Terms
- Ming Dynasty : The ruling dynasty of China for 276 years (1368–1644), following the collapse of the Mongol-led Yuan Dynasty; the last dynasty in China ruled by the ethnic Han Chinese.
- cloisonne : A decorative technique for metalwork, especially brass, whereby colored enamel is baked between raised ridges of the metal.
- lacquerwares : Objects (including boxes, tablewares, buttons, etc.) decoratively covered with a clear or colored wood finish that dries by solvent evaporation or a curing process and produces a hard, durable finish; the finish is sometimes inlaid or carved.
- porcelain : A hard, white, translucent ceramic that is made by firing kaolin and other materials.
Overview: Decorative Arts in China
The art form that the post-Renaissance West calls the decorative arts is extremely important in Chinese art. Most of the finest decorative arts were produced in large workshops or factories by essentially unknown artists, especially in the field of Chinese porcelain. Much of the best work in ceramics , textiles, and other techniques was produced over a long period by the various Imperial factories or workshops. In addition to being used by the court, these works were distributed internally and abroad on a huge scale to demonstrate the wealth and power of the Emperors. In contrast , the tradition of ink wash painting, practiced primarily by scholar-officials, developed aesthetic values similar to those of the West while long pre-dating their development there.
The Ming Dynasty
As in earlier dynasties, the Ming Dynasty saw a flourishing in the arts, whether it was painting, poetry, music, literature, or dramatic theater. In the decorative arts, carved designs in lacquerwares and designs glazed onto porcelain wares displayed intricate scenes similar in complexity to those in painting. These items could be found in the homes of the wealthy alongside embroidered silks and wares of jade, ivory, and cloisonné. The houses of the rich were also furnished with rosewood furniture and feathery latticework. The writing materials in a scholar’s private study, including elaborately carved brush holders made of stone or wood, were all designed and arranged ritually to give an aesthetic appeal.
The major production centers for porcelain items in the Ming Dynasty were Jingdezhen in the Jiangxi province and Dehua in the Fujian province. By the 16th century, the Dehua porcelain factories catered to European tastes by creating Chinese export porcelain. Individual potters also became known, such as He Chaozong, who became famous in the early 17th century for his style of white porcelain sculpture . Scholars estimate that about 16% of late Ming era Chinese ceramic exports were sent to Europe, while the rest were destined for Japan and South East Asia. Beginning in the Ming Dynasty, ivory began to be used for small statuettes of the gods and others.
Connoisseurship in the late Ming period centered around these items of refined artistic taste, which provided work for art dealers and even underground scam artists who made fake imitations of originals and false attributions to works of art. However, there were guides to help the wary new connoisseur; in Liu Tong’s book printed in 1635, he told his readers various ways to differentiate between fake and authentic pieces of art. He revealed that a Xuande era (1426–1435) bronzework could be authenticated if one knew how to judge its sheen; porcelain wares from the Yongle era (1402–1424) could be similarly judged by their thickness.
Architecture and Urban Planning under the Ming Dynasty
Chinese urban planning and architecture under the Ming Dynasty are based on fengshui geomancy and numerology, as seen in the Forbidden City.
Describe how fengshui and numerology influenced the architecture and urban planning of the Ming Dynasty, as seen in the capital of Beijing
Key Points
- Chinese urban planning is based on fengshui geomancy and the well-field system of land division.
- Fengshui geomancy is a way of orienting buildings in an auspicious manner based on a number of elements; an auspicious site could be determined by reference to local features such as bodies of water, stars, or a compass.
- In the well-field system of land division, a square area of land is divided into nine identically-sized sections; the eight outer sections were privately cultivated by serfs, while the center section was communally cultivated on behalf of the landowning aristocrat.
- Numerology heavily influenced Imperial architecture, hence the use of nine in much of construction (nine being the greatest single digit number).
- The Forbidden City was the Chinese imperial palace from 1420 to 1912. It is located in the center of Beijing and served as the home of emperors and their households as well as the ceremonial and political center of Chinese government.
- The palace complex exemplifies traditional Chinese palatial architecture and has influenced cultural and architectural developments in East Asia and elsewhere.
Key Terms
- numerology : The study of the purported mystical relationship between numbers and the character or action of physical objects and living things.
- Forbidden City : The palace of the Ming and Qing Dynasties, which is now preserved as a museum in Beijing, China.
- fengshui : A Chinese philosophical system of harmonizing with the surrounding environment; it is closely linked to Daoism.
Chinese Architecture and Urban Planning After 1279
Fengshui Geomancy
Chinese urban planning is based on fengshui geomancy and the well-field system of land division, both used since the Neolithic age. Fengshui geomancy is a way of orienting buildings in an auspicious manner based on a number of elements. Depending on the particular style of fengshui being used, an auspicious site could be determined by reference to local features such as bodies of water, stars, or a compass. The importance of the East (the direction of the rising sun) in orienting and siting Imperial buildings is a form of solar worship found in many ancient cultures , where there is the notion of Ruler being affiliated with the Sun.
The Well-field System and Numerology
The well-field system of land division is a system in which a square area of land is divided into nine identically-sized sections; the eight outer sections were privately cultivated by serfs, while the center section was communally cultivated on behalf of the landowning aristocrat. The basic well-field diagram is overlaid with the luoshu, a magic square divided into 9 sub-squares and linked with Chinese numerology.
Numerology heavily influenced Imperial architecture, as seen in the use of nine in much of construction (nine being the greatest single digit number). It is a common myth, for example, that there are 9,999 rooms and antechambers in the Forbidden City in Beijing—just short of the mythical 10,000 rooms in Heaven; however, this is based on oral tradition and is not supported by survey evidence.
Beijing and the Forbidden City
Beijing became the capital of China after the Mongol invasion of the 13th century, completing the easterly migration of the Chinese capital begun in the earlier Jin dynasty . The Ming uprising in 1368 reasserted Chinese authority and fixed Beijing as the seat of imperial power for the next five centuries.
The Forbidden City was the Chinese imperial palace from the Ming Dynasty to the end of the Qing Dynasty—the years 1420 to 1912. It is located in the center of Beijing and served as the home of emperors and their households as well as the ceremonial and political center of Chinese government for almost 500 years. Constructed from 1406 to 1420, the complex consists of 980 buildings and covers 180 acres. The palace complex exemplifies traditional Chinese palatial architecture and has influenced cultural and architectural developments in East Asia and elsewhere. Traditionally, the Emperor and Empress lived in palaces on the central axis of the Forbidden City, while the Crown Prince lived at the eastern side and the concubines lived toward the back (leading to the reference of the numerous imperial concubines as the “Back Palace Three Thousand”). Later, during the mid-Qing Dynasty, the Emperor’s residence was moved to the western side of the complex.
The Forbidden City is a rectangle, measuring 961 meters from north to south and 753 meters from east to west. It consists of 980 surviving buildings with 8,886 bays of rooms. The Forbidden City remains important in the civic scheme of Beijing, with its central north-south axis remaining the central axis of the entire city. The Forbidden City is located within the larger Imperial City in Beijing, which is in turn encompassed by the Inner City. Its axis extends to the south through Tiananmen gate to Tiananmen Square, the ceremonial center of the People’s Republic of China, and on to Yongdingmen. To the north, it extends through Jingshan Hill to the Bell and Drum Towers. This axis is not exactly aligned north-south but is instead tilted by slightly more than two degrees. Researchers now believe the axis was designed in the Yuan Dynasty to be aligned with Xanadu, the other capital of their empire.
Symbolic Design
The design of the Forbidden City, from its overall layout to the smallest detail, was meticulously planned to reflect philosophical and religious principles and the majesty of Imperial power. Some noted examples of symbolic designs include:
- The use of yellow, the color of the Emperor. Almost all roofs in the Forbidden City bear yellow glazed tiles, with only two exceptions. The library at the Pavilion of Literary Profundity has black tiles because black was associated with water, and thus fire prevention; similarly, the Crown Prince’s residences have green tiles because green was associated with wood, and thus growth.
- The use of numerology. The main halls of the Outer and Inner courts, for example, are all arranged in groups of three in the shape of the Qian triagram, representing Heaven. The residences of the Inner Court, on the other hand, are arranged in groups of six in the shape of the Kun triagram, representing the Earth.
- The use of statuettes to indicate importance. The sloping ridges of building roofs are decorated with a line of statuettes led by a man riding a phoenix and followed by an imperial dragon. The number of statuettes represents the status of the building; for example, a minor building might have only 3 or 5, while the Hall of Supreme Harmony is the only building to have 10.
- The layout of buildings. The layout follows ancient customs laid down in the Classic of Rites (a collection of texts describing the social forms, administration, and ceremonial rites of the earlier Zhou dynasty).
Chinese Literati Expressionism under the Ming Dynasty
Literati Expressionism in Chinese painting was produced by scholar-bureaucrats of the Southern School, rather than by professional painters.
Differentiate the literati Southern School of Chinese painting from its professional counterpart in the North
Key Points
- Under the Ming Dynasty , Chinese culture bloomed. Narrative painting, with a wider color range and a much busier composition than the Song paintings, was immensely popular during the time.
- The Southern School of Chinese painting, often known as ” literati painting,” is a term used to denote art and artists that stand in opposition to the formal Northern School of painting. Southern School painters generally worked in monochrome ink, focused on expressive brushstrokes, and used a more impressionistic approach than the Northern School’s formal attention to detail, use of color, and highly refined traditional modes and methods.
- Literati paintings are most commonly of landscapes featuring men in retirement or travelers admiring the scenery or immersed in culture. Figures are often depicted residing in isolated mountain hermitages .
- Calligraphic inscriptions, either of classical poems or ones composed by a contemporary literati (typically the painter or a friend), are also quite common in these paintings.
Key Terms
- Southern School : A style of Chinese literati painting formed during the Ming Dynasty in opposition to the formal Northern School of painting; led by scholar-bureaucrats, who had either retired from the professional world or had never been a part of it.
- Confucianism : A Chinese ethical and philosophical system developed from the teachings of the Chinese philosopher Confucious.
Overview: The Southern School and Literati Painting
Under the Ming Dynasty, Chinese culture bloomed. Narrative painting, with a wider color range and a much busier composition than the previous paintings of the Song Dynasty, was immensely popular during the time.
The Southern School of Chinese painting, often known as “literati painting,” is a term used to denote art and artists that stand in opposition to the formal Northern School of painting. Where formal and professional painters were classified as Northern School, scholar-bureaucrats, who had either retired from the professional world or who had never been a part of it, constituted the Southern School.
History
Never a formal school of art in the sense of artists training under a single master in a single studio, the Southern School is more of an umbrella term spanning a great breadth across both geography and chronology. The literati lifestyle and attitude, as well as the associated style of painting, can be said to go back to early periods of Chinese history. However, the coining of the term “Southern School” is said to have been made by the scholar-artist Dong Qichang (1555–1636), who borrowed the concept from Ch’an (Zen) Buddhism , which also has Northern and Southern Schools.
The Literati Style and Artists
Generally, Southern School painters worked in monochrome ink, focused on expressive brushstrokes, and used a somewhat more impressionistic approach than the Northern School’s formal attention to detail, use of color, and highly refined traditional modes and methods. The stereotypical literati painter lived in retirement either in the mountains or other rural areas, not entirely isolated but immersed in natural beauty and far from mundane concerns. These artists tended to be lovers of culture, enjoying and taking part in all Four Arts of the Chinese Scholar (painting, calligraphy , music, and games of skill and strategy) as touted by Confucianism . Many artists would combine these elements into their work and would gather with one another to share their interests.
Literati paintings are most commonly of landscapes, often of the shanshui (“mountain water”) genre . Many feature scholars in retirement or travelers admiring the scenery or immersed in culture. Figures are often depicted carrying or playing guqin (a plucked seven-string Chinese musical instrument of the zither family) and residing in quite isolated mountain hermitages. Calligraphic inscriptions, either of classical poems or ones composed by a contemporary literati (typically the painter or a friend), are also quite common. While this sort of landscape with certain features and elements is the standard stereotypical Southern School painting, the genre actually varied quite widely in rejecting the formal strictures of the Northern School. The painters sought the freedom to experiment with subjects and styles.
Like other traditions in Chinese art, the early Southern style soon acquired a classic status and was often copied and imitated, with later painters sometimes producing sets of paintings each in the style of a different classic artist. Though greatly affected by the confrontation with Western painting from the 18th century on, the style continued to be practiced until at least the 20th century.
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At the end of this chapter, you should be able to:
Explain why health and well-being in early childhood is so important.
Describe qualities and benefits of high-quality early care and education programs.
Outline what the book will be addressing in regards to safety, health, and nutrition.
Discuss what licensing is and its role in keeping children safe and healthy.
Compare and contrast Title 22 and Title 5 licensing requirements.
A culture of wellness exists when staff and child health and safety are valued, supported, and promoted through health & wellness programs, policies, and environment.
1
Introduction
Evidence shows that experiences in childhood are extremely important for a child’s healthy development and lifelong learning. How a child develops during this time affects future cognitive, social, emotional, language, and physical development, which in turn influences school readiness and later success in life.
Research on a number of adult health and medical conditions points to pre-disease pathways that have their beginnings in early and middle childhood.
During early childhood, the human brain grows to 90 percent of its adult size by age 3. Early childhood represents the period when young children reach developmental milestones that include:
Emotional regulation and attachment
Language development
Cognitive development
Physical development (motor skills)
All of these milestones can be significantly delayed when young children experience inadequate caregiving, environmental stressors, and other negative risk factors. These stressors and factors can affect the brain and may seriously compromise a child’s physical, social-emotional, and cognitive growth and development.
More than any other developmental periods, childhood sets the stage for:
School success
Health literacy
Self-discipline
The ability to make good decisions about risky situations
Eating habits
Conflict negotiation and healthy relationships with family and friends
3
Understanding Childhood Health Concerns
Although young children are typically healthy, it is during this time that they are at risk for conditions such as:
Developmental and behavioral disorders
Child maltreatment
Asthma and other chronic conditions
Obesity
Dental caries (cavities)
Unintentional injuries
While typically nonfatal, these conditions affect children, their education, their relationships with others, and the health and well-being of the adolescents and adults they will become.
5
Emerging Issues in Childhood Health
The keys to understanding childhood health are recognizing the important roles these periods play in adult health and well-being and focusing on conditions and illnesses that can seriously limit children’s abilities to learn, grow, play, and become healthy adults.
Prevention efforts in early and middle childhood can have lasting benefits. Emerging issues in early and middle childhood include implementing and evaluating multidisciplinary public health interventions that address social determinants of health by:
Fostering knowledgeable and nurturing families, parents, and caregivers
Creating supportive and safe environments in home, schools, and communities
Increasing access to high-quality health care
6
Early Childhood Development and Education
Early childhood, particularly the first 5 years of life, impacts long–term social, cognitive, emotional, and physical development.
Healthy development in early childhood helps prepare children for the educational experiences of kindergarten and beyond.
Early childhood development and education opportunities are affected by various environmental and social factors, including:
Early life stress
Socioeconomic status
Relationships with parents and caregivers
Access to early education programs
Early life stress and adverse events can have a lasting impact on the mental and physical health of children.
Specifically, early life stress can contribute to developmental delays and poor health outcomes in the future. Stressors such as physical abuse, family instability, unsafe neighborhoods, and poverty can cause children to have inadequate coping skills, difficulty regulating emotions, and reduced social functioning compared to other children their age.
Additionally, exposure to environmental hazards, such as lead in the home, can negatively affect a child's health and cause cognitive developmental delays. Research shows that lead exposure disproportionately affects children from minority and low–income households and can adversely affect their readiness for school.
The socioeconomic status of young children's families and communities also significantly affects their educational outcomes. Specifically, poverty has been shown to negatively influence the academic achievement of young children. Research shows that, in their later years, children from disadvantaged backgrounds are more likely to need special education, repeat grades, and drop out of high school. Children from communities with higher socioeconomic status and more resources experience safer and more supportive environments and better early education programs.
Note
The Effects of Poverty on Education
“Despite being one of the most developed countries in the world, the United States has one of the highest rates of childhood poverty globally.”
7
“Poverty has a particularly adverse effect on the academic outcomes of children, especially during early childhood.”
8
Research has shown that children from families in poverty enter school with a readiness gap. Contributions to this gap include:
Poor physical development and health (due to poor nutrition and lack of access to medical care)
Challenges with concentration, memory, attentiveness, curiosity, and motivation
9
due to the chronic stress of living in poverty
Greater risk for behavioral and emotional problems
Exposure to environmental hazards (such as lead paint) and violence in their communities.
Two additional things that are important to note:
This gap disproportionately affects Black and Latinx children.
Families experiencing poverty have challenges finding affordable, high-quality early care and education programs and are often in districts with under-resourced schools.
10
Early childhood programs are a critical outlet for fostering the mental and physical development of young children. According to the Center on the Development Child at Harvard University’s
A Science-Based Framework for Early Childhood Policy,
“ The principal elements that have consistently produced positive impacts include:
highly skilled teachers;
small class sizes and high adult-to-child ratios;
age-appropriate curricula and stimulating materials in a safe physical setting;
a language-rich environment;
warm, responsive interactions between staff and children; and
high and consistent levels of child participation.”
11
The National Association for the Education for Young Children says that high quality programs:
Create caring communities of learners in which children develop relationships with each and the teachers and each child and family are included.
Teach to support children’s development and learning by being intentional with the environmental design, materials, and activities and by providing positive guidance for children’s behavior.
Have developmentally appropriate curriculum that helps children learn and grow that sets challenging, yet achievable goals for children, balances adult instruction and group activities with play and child-chosen experiences, provides enough time for deep engagement, and is based on the children’s interests, abilities, and knowledge.
Regularly assesses children’s development and learning to inform their environmental design, curriculum, and interactions with children and their families.
Is founded on partnerships with families in which families are respected and valued, share their goals and concerns, are encouraged to participate, and with clear communication (in a family’s home language whenever possible).
12
And you can check out the checklist
15 Must-Haves for All Child Care Programs
published by The Administration for Children and Families Office of Child Care in Appendix A.
Early childhood development and education programs can also help reduce educational gaps. For example, Head Start is a federally funded early childhood program that provides comprehensive services for children from low–income families. Head Start aims to improve health outcomes, increase learning and social skills, and close the gap in readiness to learn for children from low–income families and at-risk children. Enrolling children in full-day kindergarten after the completion of preschool has also been shown to improve academic achievement.
Furthermore, extended early childhood programs for children up to 3rd grade, also referred to as booster programs, can provide comprehensive educational, health, and social services to complement standard early childhood and kindergarten programs. These programs help sustain and bolster early developmental and academic gains. Characteristic of such programs include:
Low student-teacher ratio
Teacher training
Creation of school-family partnerships
School meals
Provision of transportation to and from school
Health care services and referrals
Home visitation
Supportive social services
Quality education in elementary school is necessary to reinforce early childhood interventions and prevent their positive effects from fading over time. Research also shows that school quality has an impact on both the short– and long–term educational attainment of children, as well as on their health. For example, children who enroll in low–quality schools with limited health resources, safety concerns, and low teacher support are more likely to have poorer physical and mental health.
The developmental and educational opportunities that children have access to in their early years have a lasting impact on their health as adults. The Carolina Abecedarian Project found that the children in the study who participated in a high–quality and comprehensive early childhood education program, including health care and nutritional components, were in better health than those who did not. The study found that, at age 21, the people who participated in the comprehensive early education program exhibited fewer risky health behaviors—for example, they were less likely to binge drink alcohol, smoke cigarettes, and use illegal drugs. This group also self–reported better health and had a lower number of deaths.
Furthermore, by their mid–30s the children who participated in the comprehensive early childhood development and education program had a lower risk for heart disease and associated risk factors, including obesity, high blood pressure, elevated blood sugar, and high cholesterol. These studies show that quality early childhood development and education programs can play a key role in reducing risky health behaviors and preventing or delaying the onset of chronic disease in adulthood. We will look at what high quality programming looks like at the end of the chapter.
Early childhood development and education are key determinants of future health and well–being. Addressing the disparities in access to early childhood development and education opportunities can greatly bolster young children’s future health outcomes.
Additional research is needed to increase the evidence base for what can successfully impact the effects of childhood development and education on health outcomes and disparities. This additional evidence will facilitate public health efforts to address early childhood development and education as social determinants of health.
14
Importance of Considering Holistic Development
Early childhood education (ECE) is not a singular concept, but rather a holistic concept that focuses on several aspects of a child's development, including their cognitive, social, emotional, moral, spiritual, and physical well-being (American Academy of Pediatrics 2012; Chisholm 2004; Tinajero & Loizillon 2012). According to Shonkoff,
et al.
(2011), debates about early childhood education often focus on education and the enhancement of children's cognitive skills and later academic progress. However, these authors stress the importance of viewing children in a holistic manner as part of a bigger system. In this manner, early childhood education becomes a vehicle for enhancing the physical, cognitive, mental, social and economic well-being of individuals and the societies in which they live. Early care and education programs should enhance multiple interrelated dimensions of a child's life; including health and safety, nutrition, emotional well-being, and social competence.
15
Focus on Wellness
Rather than waiting for health issues to arise, families and early childhood education programs should focus on supporting children’s wellness. “Wellness describes the entirety of one’s physical, emotional, and social health; this includes all aspects of functioning in the world (physiological, intellectual, social, and spiritual), as well as subjective feelings of well-being. A child who is doing well frequently experiences joy, delight, and wonder, is secure and safe in his/her family and community, and is continually expanding and deepening his/her engagement with the world around him/her.”
16
Wellness is an active process. It requires awareness and directed, thoughtful attention to the choices we make. Early care and education programs can play a critical role in helping children, families and staff commit to and implement healthy lifestyle choices that promote both physical and mental well-being. The two, in fact, are closely linked. Our feelings, thoughts, and behaviors directly impact our physical health. Similarly, our physical health status has a direct impact on our feelings, thoughts, and behaviors.
18
We must also support children’s mental well-being and help them navigate everyday stress and adversity as well as trauma and significant sources of stress. The American Psychological Association shares that “[b]uilding resilience — the ability to adapt well to adversity, trauma, tragedy, threats or even significant sources of stress — can help our children manage stress and feelings of anxiety and uncertainty.”
19
It is important that children are in an environment that keeps them physically and emotionally safe and healthy and provides sound nutrition. As an early educator, providing these requires attention, planning, and intention.
Introduction to Safety, Health, and Nutrition
This book is divided into three sections. These include:
Safety
Health
Nutrition
Safety
Children are curious and eager to learn. They depend on their caregivers to keep them safe by making sure that nothing within a child’s reach can harm them. Injuries are a serious health risk to young children. But most injuries are predictable and preventable.
20
ECE programs can prevent risks and unnecessary harm to children by committing to a culture of safety. A culture of safety prioritizes safety at all levels. It encourages programs to learn from past problems and prevent them in the future.
22
Programs should not assume that nothing will ever go wrong. In fact, they should plan that something is going to go wrong. And their goal is to make it as hard as possible for things to go wrong.
23
Chapters 2 through 5 will focus on ways programs can protect children’s safety.
Chapter 2 discusses active supervision and creating a culture of safety
Chapter 5 addresses caring for minor injuries and managing emergencies
Chapter 6 discusses child maltreatment (abuse and neglect)
Health
“Health is more than merely the absence of disease—it is an evolving human resource that helps children and adults adapt to the challenges of everyday life, resist infections, cope with adversity, feel a sense of personal well-being, and interact with their surroundings in ways that promote successful development.”
24
As mentioned at the beginning of the chapter, research is showing that many adult health issues, such as high blood pressure, heart disease, and diabetes, are linked to what happens during early childhood (and even prenatally!). We also know that during early childhood there are biological systems that are more sensitive to environmental factors (such as child maltreatment, malnutrition, and recurring issues to infectious disease).
26
It is vital for children and their families to have support for children’s physical, oral, and mental health. This happens through promoting health and protection from illness.
Chapters 7 through 11 focus on children’s health.
Chapter 7 examines promoting health
Chapter 8 looks at preventing illness
Chapter 9 addresses supportive health care
Chapter 10 describes special health care needs during childhood
Chapter 11 discusses children’s mental health
Nutrition
Healthy eating and being active are essential to a child's well-being. Children who are under- or over-nourished are at risk for chronic health problems.
27
Early childhood is an important time for developing healthy habits for life. Children’s bodies grow and develop in ways that affect the way they think, eat, and behave.
28
A healthy diet not only affects growth, but also immunity, intellectual capabilities, and emotional well-being. Families and educators must ensure that children receive an adequate amount of needed nutrients to provide a strong foundation for the rest of their lives.
29
Chapters 12 through 15 focus on nutrition for children.
Chapter 12 delves into basic nutrition for children
Chapter 13 examines protecting nutrition and wellness
Chapter 14 discusses providing good nutrition
Chapter 15 addresses menu planning and food safety
Health, safety and nutrition are closely intertwined and dependent on one another. Each component can impact the others in positive or negative ways. The status of each has a direct effect on the quality of the others and a person’s total well-being. For a young child’s optimal development, they need a balance of health, safety and nutrition. When an imbalance occurs the person often experiences concerns in two or more of the three components. For example, when a child has an ear infection her balance may be affected, making her more likely to fall or injure herself on the playground. Or she may not take interest in eating breakfast which could lead to low blood sugar and decreased alertness for cognitive and physical functions. Conversely, a nutritious diet can promote good health and physical development. A child’s nutrition, physical health, and the safety of her environment all play a role in her overall well-being.
Introduction to Licensing for Child Care Centers in Wisconsin
Licensing for child care programs in the state of Wisconsin is overseen by the Department of Children and Families, whose primary mission is to ensure the health and safety of all children enrolled in licensed child care facilities in Wisconsin.
 By definition, both types of child care facilities provide nonmedical, age appropriate care and supervision of infant to school-age children for less than 14 consecutive hours at a time.
Child care centers
provide care in a large-group setting of nine or more children, usually operate in an institutional or commercial building, and must meet a number of requirements regarding their physical facilities, and the services they provide. For the most part, when this book refers to licensing requirements, it will be referencing licensing for child care centers.
Family child care homes
provide care in small-group settings in the licensee’s private house. The definition of family child care homes, are providers that care for no more than 8 children at any one time.
The key to licensing’s effort to protect the health and safety of children in child care is a thorough and fair licensing and inspection program that ensures all facilities are in compliance. Community Care Licensing is mandated by law to ensure that licensed facilities meet established health and safety standards and that the licensee has access to all relevant information about the department.
Once a facility meets all the requirements to merit a license, licensing’s principal way of helping facilities maintain compliance is through periodic unannounced site visits by licensing representative. In addition to conducting these inspections, the licensing representatives work with licensees to address any needed changes, and conduct follow-up visits to confirm that problems have been eliminated. It is also the role of the licensing representatives to investigate any complaints about a facility and consult with licensees to ensure they are aware of their rights and responsibilities.
Licensing also provides ready access to the child care advocate program. The advocates serve as a link between licensing and the community of licensees, provide information about licensed child care to families and the public, act as a liaison with businesses, child care organizations, and resource and referral agencies, and coordinate complaints and concerns on behalf of children in care. As a result, licensing is both an enforcement agency and a resource on health and safety requirements.31
TABLE DCF 251.055 Licensing Rules for Wisconsin Group Child Care Centers
Maximum Group Size and Minimum Number of Child Care Workers in Group Child Care Centers Age of Children Minimum Number of Child Care Workers to Children
Tabel 1.1 - Maximum Number of Children in a Group
Age Group
Ratio
Maximum Group Size
Birth to 2 Years
1:4
8
2 years to 2½ Years
1:6
12
2½ Years to 3 Years
1:8
16
3 Years to 4 Years
1:10
20
4 Years to 5 Years
1:13
26
5 Years to 6 Years
1:17
34
6 Years and Over
1:18
36
Accreditation from the National Association for the Education of Young Childre
While not legal regulations, there are even further requirements in place for programs that choose to pursue voluntary accreditation by the National Association for the Education of Young Children. While licensing regulations ensure that children stay safe and healthy, high quality care goes even further to provide the best start for young children. One reason that programs choose to become NAEYC accredited is to document the quality of care and education they provide children and families they serve. There are other processes and assessments that programs may use to ensure high quality, as well.
Pause to Reflect
As you progress through this book and course, what connections can you make about how being knowledgeable about health, safety, and nutrition will support early childhood educators in both following licensing and other applicable regulations and ensuring they provide high quality care for young children and their families?
Summary
Early childhood is a critical time in development. Many outcomes, both positive and negative, have their beginnings in these years. It is vital that children’s health and safety be protected. High-quality early care and education programs can play a valuable role in improving outcomes for children.
Resources for Further Exploration
National Resource Center For Health and Safety In Child Care and Early Education
:
https://nrckids.org/