<IP_ADDRESS>: The Rime of the Ancient Mariner
The Rime of the Ancient Mariner
The Rime of the Ancient Mariner License: Public DomainHow a Ship having passed the Line was driven by storms to the cold Country towards the South Pole; and how from thence she made her course to the tropical Latitude of the Great Pacific Ocean; and of the strange things that befell; and in what manner the Ancyent Marinere came back to his own Country.
It is an ancient Mariner,
And he stoppeth one of three.
'By thy long grey beard and glittering eye,
Now wherefore stopp'st thou me?
The Bridegroom's doors are opened wide,
And I am next of kin;
The guests are met, the feast is set:
May'st hear the merry din.'
He holds him with his skinny hand,
'There was a ship,' quoth he.
'Hold off! unhand me, grey-beard loon!'
Eftsoons his hand dropt he.
He holds him with his glittering eye—
The Wedding-Guest stood still,
And listens like a three years' child:
The Mariner hath his will.
The Wedding-Guest sat on a stone:
He cannot choose but hear;
And thus spake on that ancient man,
The bright-eyed Mariner.
'The ship was cheered, the harbour cleared,
Merrily did we drop
Below the kirk, below the hill,
Below the lighthouse top.
The Sun came up upon the left,
Out of the sea came he!
And he shone bright, and on the right
Went down into the sea.
Higher and higher every day,
Till over the mast at noon—'
The Wedding-Guest here beat his breast,
For he heard the loud bassoon.
The bride hath paced into the hall,
Red as a rose is she;
Nodding their heads before her goes
The merry minstrelsy.
The Wedding-Guest he beat his breast,
Yet he cannot choose but hear;
And thus spake on that ancient man,
The bright-eyed Mariner.
And now the STORM-BLAST came, and he
Was tyrannous and strong:
He struck with his o'ertaking wings,
And chased us south along.

And now there came both mist and snow,
And it grew wondrous cold:
And ice, mast-high, came floating by,
As green as emerald.
And through the drifts the snowy clifts
Did send a dismal sheen:
Nor shapes of men nor beasts we ken—
The ice was all between.
The ice was here, the ice was there,
The ice was all around:
It cracked and growled, and roared and howled,
Like noises in a swound!
At length did cross an Albatross,
Thorough the fog it came;
As if it had been a Christian soul,
We hailed it in God's name.
It ate the food it ne'er had eat,
And round and round it flew.
The ice did split with a thunder-fit;
The helmsman steered us through!
And a good south wind sprung up behind;
The Albatross did follow,
And every day, for food or play,
Came to the mariner's hollo!
In mist or cloud, on mast or shroud,
It perched for vespers nine;
Whiles all the night, through fog-smoke white,
Glimmered the white Moon-shine.'
'God save thee, ancient Mariner!
From the fiends, that plague thee thus!—
Why look'st thou so?'—With my cross-bow
I shot the ALBATROSS.
PART IIThe Sun now rose upon the right:
Out of the sea came he,
Still hid in mist, and on the left
Went down into the sea.
And the good south wind still blew behind,
But no sweet bird did follow,
Nor any day for food or play
Came to the mariner's hollo!
And I had done a hellish thing,
And it would work 'em woe:
For all averred, I had killed the bird
That made the breeze to blow.
Ah wretch! said they, the bird to slay,
That made the breeze to blow!
Nor dim nor red, like God's own head,
The glorious Sun uprist:
Then all averred, I had killed the bird
That brought the fog and mist.
'Twas right, said they, such birds to slay,
That bring the fog and mist.
The fair breeze blew, the white foam flew,
The furrow followed free;
We were the first that ever burst
Into that silent sea.
Down dropt the breeze, the sails dropt down,
'Twas sad as sad could be;
And we did speak only to break
The silence of the sea!
All in a hot and copper sky,
The bloody Sun, at noon,
Right up above the mast did stand,
No bigger than the Moon.
Day after day, day after day,
We stuck, nor breath nor motion;
As idle as a painted ship
Upon a painted ocean.
Water, water, every where,
And all the boards did shrink;
Water, water, every where,
Nor any drop to drink.
The very deep did rot: O Christ!
That ever this should be!
Yea, slimy things did crawl with legs
Upon the slimy sea.
About, about, in reel and rout
The death-fires danced at night;
The water, like a witch's oils,
Burnt green, and blue and white.
And some in dreams assurèd were
Of the Spirit that plagued us so;
Nine fathom deep he had followed us
From the land of mist and snow.
And every tongue, through utter drought,
Was withered at the root;
We could not speak, no more than if
We had been choked with soot.
Ah! well a-day! what evil looks
Had I from old and young!
Instead of the cross, the Albatross
About my neck was hung.
PART IIIThere passed a weary time. Each throat
Was parched, and glazed each eye.
A weary time! a weary time!
How glazed each weary eye,
When looking westward, I beheld
A something in the sky.
At first it seemed a little speck,
And then it seemed a mist;
It moved and moved, and took at last
A certain shape, I wist.
A speck, a mist, a shape, I wist!
And still it neared and neared:
As if it dodged a water-sprite,
It plunged and tacked and veered.

I bit my arm, I sucked the blood,
And cried, A sail! a sail!

As they were drinking all.
See! see! (I cried) she tacks no more!
Hither to work us weal;
Without a breeze, without a tide,
She steadies with upright keel!
The western wave was all a-flame.
The day was well nigh done!
Almost upon the western wave
Rested the broad bright Sun;
When that strange shape drove suddenly
Betwixt us and the Sun.
And straight the Sun was flecked with bars,
(Heaven's Mother send us grace!)
As if through a dungeon-grate he peered
With broad and burning face.
Alas! (thought I, and my heart beat loud)
How fast she nears and nears!
Are those her sails that glance in the Sun,
Like restless gossameres?
Are those her ribs through which the Sun
Did peer, as through a grate?
And is that Woman all her crew?
Is that a DEATH? and are there two?
Is DEATH that woman's mate?
Her lips were red, her looks were free,
Her locks were yellow as gold:
Her skin was as white as leprosy,
The Night-mare LIFE-IN-DEATH was she,
Who thicks man's blood with cold.
The naked hulk alongside came,
And the twain were casting dice;
'The game is done! I've won! I've won!'
Quoth she, and whistles thrice.
The Sun's rim dips; the stars rush out;
At one stride comes the dark;
With far-heard whisper, o'er the sea,
Off shot the spectre-bark.
We listened and looked sideways up!
Fear at my heart, as at a cup,
My life-blood seemed to sip!
The stars were dim, and thick the night,
The steersman's face by his lamp gleamed white;
From the sails the dew did drip—
Till clomb above the eastern bar
The hornèd Moon, with one bright star
Within the nether tip.

Four times fifty living men,
(And I heard nor sigh nor groan)
With heavy thump, a lifeless lump,
They dropped down one by one.
The souls did from their bodies fly,—
They fled to bliss or woe!
And every soul, it passed me by,
Like the whizz of my cross-bow!
PART IV'I fear thee, ancient Mariner!
I fear thy skinny hand!
And thou art long, and lank, and brown,
As is the ribbed sea-sand.
I fear thee and thy glittering eye,
And thy skinny hand, so brown.'—
Fear not, fear not, thou Wedding-Guest!
This body dropt not down.
Alone, alone, all, all alone,
Alone on a wide wide sea!
And never a saint took pity on
My soul in agony.
The many men, so beautiful!
And they all dead did lie:
And a thousand thousand slimy things
Lived on; and so did I.
I looked upon the rotting sea,
And drew my eyes away;
I looked upon the rotting deck,
And there the dead men lay.
I looked to heaven, and tried to pray;
But or ever a prayer had gusht,
A wicked whisper came, and made
My heart as dry as dust.

The cold sweat melted from their limbs,
Nor rot nor reek did they:
The look with which they looked on me
Had never passed away.

Seven days, seven nights, I saw that curse,
And yet I could not die.
The moving Moon went up the sky,
And no where did abide:
Softly she was going up,
And a star or two beside—
Her beams bemocked the sultry main,
Like April hoar-frost spread;
But where the ship's huge shadow lay,
The charmèd water burnt alway
A still and awful red.
Beyond the shadow of the ship,
I watched the water-snakes:
They moved in tracks of shining white,
And when they reared, the elfish light
Fell off in hoary flakes.
Within the shadow of the ship
I watched their rich attire:
Blue, glossy green, and velvet black,
They coiled and swam; and every track
Was a flash of golden fire.
O happy living things! no tongue
Their beauty might declare:
A spring of love gushed from my heart,
And I blessed them unaware:
Sure my kind saint took pity on me,
And I blessed them unaware.
The self-same moment I could pray;
And from my neck so free
The Albatross fell off, and sank
Like lead into the sea.
PART VOh sleep! it is a gentle thing,
Beloved from pole to pole!
To Mary Queen the praise be given!
She sent the gentle sleep from Heaven,
That slid into my soul.
The silly buckets on the deck,
That had so long remained,
I dreamt that they were filled with dew;
And when I awoke, it rained.
My lips were wet, my throat was cold,
My garments all were dank;
Sure I had drunken in my dreams,
And still my body drank.
I moved, and could not feel my limbs:
I was so light—almost
I thought that I had died in sleep,
And was a blessed ghost.
And soon I heard a roaring wind:
It did not come anear;
But with its sound it shook the sails,
That were so thin and sere.
The upper air burst into life!
And a hundred fire-flags sheen,
To and fro they were hurried about!
And to and fro, and in and out,
The wan stars danced between.
And the coming wind did roar more loud,
And the sails did sigh like sedge,
And the rain poured down from one black cloud;
The Moon was at its edge.
The thick black cloud was cleft, and still
The Moon was at its side:
Like waters shot from some high crag,
The lightning fell with never a jag,
A river steep and wide.
The loud wind never reached the ship,
Yet now the ship moved on!
Beneath the lightning and the Moon
The dead men gave a groan.
They groaned, they stirred, they all uprose,
Nor spake, nor moved their eyes;
It had been strange, even in a dream,
To have seen those dead men rise.
The helmsman steered, the ship moved on;
Yet never a breeze up-blew;
The mariners all 'gan work the ropes,
Where they were wont to do;
They raised their limbs like lifeless tools—
We were a ghastly crew.
The body of my brother's son
Stood by me, knee to knee:
The body and I pulled at one rope,
But he said nought to me.
'I fear thee, ancient Mariner!'
Be calm, thou Wedding-Guest!
'Twas not those souls that fled in pain,
Which to their corses came again,
But a troop of spirits blest:
For when it dawned—they dropped their arms,
And clustered round the mast;
Sweet sounds rose slowly through their mouths,
And from their bodies passed.
Around, around, flew each sweet sound,
Then darted to the Sun;
Slowly the sounds came back again,
Now mixed, now one by one.
Sometimes a-dropping from the sky
I heard the sky-lark sing;
Sometimes all little birds that are,
How they seemed to fill the sea and air
With their sweet jargoning!
And now 'twas like all instruments,
Now like a lonely flute;
And now it is an angel's song,
That makes the heavens be mute.
It ceased; yet still the sails made on
A pleasant noise till noon,
A noise like of a hidden brook
In the leafy month of June,
That to the sleeping woods all night
Singeth a quiet tune.
Till noon we quietly sailed on,
Yet never a breeze did breathe:
Slowly and smoothly went the ship,
Moved onward from beneath.
Under the keel nine fathom deep,
From the land of mist and snow,
The spirit slid: and it was he
That made the ship to go.
The sails at noon left off their tune,
And the ship stood still also.
The Sun, right up above the mast,
Had fixed her to the ocean:
But in a minute she 'gan stir,
With a short uneasy motion—
Backwards and forwards half her length
With a short uneasy motion.
Then like a pawing horse let go,
She made a sudden bound:
It flung the blood into my head,
And I fell down in a swound.
How long in that same fit I lay,
I have not to declare;
But ere my living life returned,
I heard and in my soul discerned
Two voices in the air.
'Is it he?' quoth one, 'Is this the man?

The spirit who bideth by himself
In the land of mist and snow,
He loved the bird that loved the man
Who shot him with his bow.'
The other was a softer voice,
As soft as honey-dew:
Quoth he, 'The man hath penance done,
And penance more will do.'
PART VI First Voice'But tell me, tell me! speak again,
Thy soft response renewing—
What makes that ship drive on so fast?
What is the ocean doing?'
Second VoiceStill as a slave before his lord,
The ocean hath no blast;
His great bright eye most silently
Up to the Moon is cast—
If he may know which way to go;
For she guides him smooth or grim.
See, brother, see! how graciously
She looketh down on him.'
First Voice'But why drives on that ship so fast,
Without or wave or wind?'
Second Voice'The air is cut away before,
And closes from behind.
Fly, brother, fly! more high, more high!
Or we shall be belated:
For slow and slow that ship will go,
When the Mariner's trance is abated.'
I woke, and we were sailing on
As in a gentle weather:
'Twas night, calm night, the moon was high;
The dead men stood together.
All stood together on the deck,
For a charnel-dungeon fitter:
All fixed on me their stony eyes,
That in the Moon did glitter.
The pang, the curse, with which they died,
Had never passed away:
I could not draw my eyes from theirs,
Nor turn them up to pray.
And now this spell was snapt: once more
I viewed the ocean green,
And looked far forth, yet little saw
Of what had else been seen—
Like one, that on a lonesome road
Doth walk in fear and dread,
And having once turned round walks on,
And turns no more his head;
Because he knows, a frightful fiend
Doth close behind him tread.
But soon there breathed a wind on me,
Nor sound nor motion made:
Its path was not upon the sea,
In ripple or in shade.
It raised my hair, it fanned my cheek
Like a meadow-gale of spring—
It mingled strangely with my fears,
Yet it felt like a welcoming.
Swiftly, swiftly flew the ship,
Yet she sailed softly too:
Sweetly, sweetly blew the breeze—
On me alone it blew.
Oh! dream of joy! is this indeed
The light-house top I see?
Is this the hill? is this the kirk?
Is this mine own countree?
We drifted o'er the harbour-bar,
And I with sobs did pray—
O let me be awake, my God!
Or let me sleep alway.
The harbour-bay was clear as glass,
So smoothly it was strewn!
And on the bay the moonlight lay,
And the shadow of the Moon.
The rock shone bright, the kirk no less,
That stands above the rock:
The moonlight steeped in silentness
The steady weathercock.
And the bay was white with silent light,
Till rising from the same,
Full many shapes, that shadows were,
In crimson colours came.
A little distance from the prow
Those crimson shadows were:
I turned my eyes upon the deck—
Oh, Christ! what saw I there!
Each corse lay flat, lifeless and flat,
And, by the holy rood!
A man all light, a seraph-man,
On every corse there stood.
This seraph-band, each waved his hand:
It was a heavenly sight!
They stood as signals to the land,
Each one a lovely light;
This seraph-band, each waved his hand,
No voice did they impart—
No voice; but oh! the silence sank
Like music on my heart.
But soon I heard the dash of oars,
I heard the Pilot's cheer;
My head was turned perforce away
And I saw a boat appear.
The Pilot and the Pilot's boy,
I heard them coming fast:
Dear Lord in Heaven! it was a joy
The dead men could not blast.
I saw a third—I heard his voice:
It is the Hermit good!
He singeth loud his godly hymns
That he makes in the wood.
He'll shrieve my soul, he'll wash away
The Albatross's blood.
PART VIIThis Hermit good lives in that wood
Which slopes down to the sea.
How loudly his sweet voice he rears!
He loves to talk with marineres
That come from a far countree.
He kneels at morn, and noon, and eve—
He hath a cushion plump:
It is the moss that wholly hides
The rotted old oak-stump.
The skiff-boat neared: I heard them talk,
'Why, this is strange, I trow!
Where are those lights so many and fair,
That signal made but now?'
'Strange, by my faith!' the Hermit said—
'And they answered not our cheer!
The planks looked warped! and see those sails,
How thin they are and sere!
I never saw aught like to them,
Unless perchance it were
Brown skeletons of leaves that lag
My forest-brook along;
When the ivy-tod is heavy with snow,
And the owlet whoops to the wolf below,
That eats the she-wolf's young.'
'Dear Lord! it hath a fiendish look—
(The Pilot made reply)
I am a-feared'—'Push on, push on!'
Said the Hermit cheerily.
The boat came closer to the ship,
But I nor spake nor stirred;
The boat came close beneath the ship,
And straight a sound was heard.
Under the water it rumbled on,
Still louder and more dread:
It reached the ship, it split the bay;
The ship went down like lead.
Stunned by that loud and dreadful sound,
Which sky and ocean smote,
Like one that hath been seven days drowned
My body lay afloat;
But swift as dreams, myself I found
Within the Pilot's boat.
Upon the whirl, where sank the ship,
The boat spun round and round;
And all was still, save that the hill
Was telling of the sound.
I moved my lips—the Pilot shrieked
And fell down in a fit;
The holy Hermit raised his eyes,
And prayed where he did sit.
I took the oars: the Pilot's boy,
Who now doth crazy go,
Laughed loud and long, and all the while
His eyes went to and fro.
'Ha! ha!' quoth he, 'full plain I see,
The Devil knows how to row.'
And now, all in my own countree,
I stood on the firm land!
The Hermit stepped forth from the boat,
And scarcely he could stand.
'O shrieve me, shrieve me, holy man!'
The Hermit crossed his brow.
'Say quick,' quoth he, 'I bid thee say—
What manner of man art thou?'
Forthwith this frame of mine was wrenched
With a woful agony,
Which forced me to begin my tale;
And then it left me free.
Since then, at an uncertain hour,
That agony returns:
And till my ghastly tale is told,
This heart within me burns.
I pass, like night, from land to land;
I have strange power of speech;
That moment that his face I see,
I know the man that must hear me:
To him my tale I teach.
What loud uproar bursts from that door!
The wedding-guests are there:
But in the garden-bower the bride
And bride-maids singing are:
And hark the little vesper bell,
Which biddeth me to prayer!
O Wedding-Guest! this soul hath been
Alone on a wide wide sea:
So lonely 'twas, that God himself
Scarce seemèd there to be.
O sweeter than the marriage-feast,
'Tis sweeter far to me,
To walk together to the kirk
With a goodly company!—
To walk together to the kirk,
And all together pray,
While each to his great Father bends,
Old men, and babes, and loving friends
And youths and maidens gay!
Farewell, farewell! but this I tell
To thee, thou Wedding-Guest!
He prayeth well, who loveth well
Both man and bird and beast.
He prayeth best, who loveth best
All things both great and small;
For the dear God who loveth us,
He made and loveth all.
The Mariner, whose eye is bright,
Whose beard with age is hoar,
Is gone: and now the Wedding-Guest
Turned from the bridegroom's door.
He went like one that hath been stunned,
And is of sense forlorn:
A sadder and a wiser man,
He rose the morrow morn.


9.6: Israel - “The Hope”
One additional national anthem will provide an opportunity to consider the connection between music and nation. This time, our analysis will reveal little about the complex history of the nation, as was the case with “Song of the Germans” and “National Anthem of South Africa.” Instead, it will shed further light on the difficulty of assigning national identity to a melody.
The national anthem of Israel, entitled “The Hope”6 (Hebrew: “Hatikvah”), has a brief and uncomplicated history. It was immediately adopted on an unofficial basis when the nation of Israel was founded in 1948, and it became the official national anthem in 2004. The text was written in 1878 by the Polish poet Naphtali Herz Imber, and it expresses yearning for a return to the Jewish homeland. “The Hope” was used as an anthem by several Zionist groups, and beginning in 1897 it was sung at the Congresses of the World Zionist Organization, which advocated for the founding of an autonomous Jewish nation. As such, it came to represent Zionist sentiment throughout the Jewish diaspora.
|
“The Hope” Composers: Giuseppe Cenci & Samuel Cohen 6. Lyricist: Naphtali Herz Imber. Performance: prisoners at the Bergen-Belsen concentration camp (1945) |
The deep significance that “The Hope” had for Jewish people is evidenced by several stories from WWII-era concentration camps. In one recorded incident, a group of Czech Jews sang “The Hope” as they were escorted into the gas chamber at Auschwitz. The guards were enraged and beat them, but could not stop the singing. Reports from other camps indicate that the song was sung frequently by Jewish prisoners and that it brought them solace. When Bergen-Belsen was liberated, the inmates also sang “The Hope”—a recording of which was captured and broadcast to the world.
The melody to which Imber’s text has always been sung was provided by Samuel Cohen in 1888. He did not compose it but rather adapted it from a melody he had heard sung in Romania. The tune, however, is not Romanian. In fact, it can be traced to a 16th-century Italian song entitled “La Mantovana,” which has been attributed to the singer Giuseppe Cenci and was first published around 1600. The melody quickly became popular and soon had been paired with texts in Dutch, Polish, Ukranian, Romanian, and English.
Bedřich Smetana, “The Moldau”
Most famously, the melody was used by the Czech composer Bedřich Smetana (1824-1884) as the main theme for his nationalist symphonic poem “The Moldau” (1874), which belongs to a larger cycle of works entitled My Homeland . Here we begin to see the complexities surrounding “The Hope.” Decades before this tune came to communicate Jewish identity, and more than half a century before it would represent the nation of Israel, it was used to signify Czech identity and national sentiment.
|
Time |
Form |
What to listen for |
|---|---|---|
|
0’00” |
A |
This passage represents the emergence of the Moldau from two small springs that join together to form a powerful current; the principal melody is shared with Israel’s national anthem, “The Hope” |
|
4’06” |
B |
This passage represents the rural landscapes through which the Moldau passes; the folk-like melody is meant to evoke the celebration of a farmer’s wedding |
|
5’34” |
C |
This passage represents a scene described by the composer as “the round dance of the mermaids in the night's moonshine” |
|
8’44” |
A’ |
The principal melody returns |
|
10’44” |
The melody shifts into the major mode |
|
|
This passage quotes from Smetana’s symphonic poem “Vyšehrad,” which is the first in the cycle |
||
|
11’12” |
My Homeland; it serves both to connect the works thematically and to represent the literal presence of the Vyšehrad castle, which stands on the banks of the Moldau |
Smetana’s “The Moldau” is an example of program music. It describes in sound the course of the famous Moldau river as it winds its way through the countryside and ultimately joins the Elbe river. “The Moldau” contains a succession of distinct sections. First, we hear the river emerge from a pair of warm and cold springs. It slowly gains strength until a mighty, expressive melody—that used for “The Hope”—bursts forth to represent the river. Next we hear the sounds of dance music as it might be played at a country wedding, followed by a nocturnal passage representing mermaids in the moonlight. Finally, the river theme returns, first in its original minor mode and then in a triumphant major.
How can an Italian melody develop and sustain both Jewish and Czech nationalistic connotations—all while continuing to be periodically mistaken for a Flemish, Polish, Ukranian, Romanian, and Scottish folk song? The answer has to do both with musical style and with the power of association. “La Mantovana” is an exceptionally simple tune. It contains two parts, one lower and one higher (a typical characteristic in many folk traditions). Both parts have a limited range and move primarily using stepwise motion. All of these attributes allow “La Mantovana” to be adapted in conformance with the conventions of various national styles.
However, association is more powerful than style. Listeners who first encountered this melody as representing the Moldau river and Czech identity will have a hard time hearing it in a different way. It has a similarly powerful (although quite different) meaning for Jews who grew up singing the Zionist lyrics. The multiple identities of the tune have created consternation in the Jewish community, and many have objected to its pairing with Imber’s text. All the same, efforts to find or create a new musical setting have always met with failure, and this melody continues to exercise enormous emotional power over a global population.


6.2: What Is Learning?
Learning Objectives
- Explain how learned behaviors are different from instincts and reflexes
- Define learning
- Recognize and define three basic forms of learning—classical conditioning, operant conditioning, and observational learning
Birds build nests and migrate as winter approaches. Infants suckle at their mother’s breast. Dogs shake water off wet fur. Salmon swim upstream to spawn, and spiders spin intricate webs. What do these seemingly unrelated behaviors have in common? They all are unlearned behaviors. Both instincts and reflexes are innate behaviors that organisms are born with. Reflexes are a motor or neural reaction to a specific stimulus in the environment. They tend to be simpler than instincts, involve the activity of specific body parts and systems (e.g., the knee-jerk reflex and the contraction of the pupil in bright light), and involve more primitive centers of the central nervous system (e.g., the spinal cord and the medulla). In contrast, instincts are innate behaviors that are triggered by a broader range of events, such as aging and the change of seasons. They are more complex patterns of behavior, involve movement of the organism as a whole (e.g., sexual activity and migration), and involve higher brain centers.
Both reflexes and instincts help an organism adapt to its environment and do not have to be learned. For example, every healthy human baby has a sucking reflex, present at birth.  Nobody teaches the baby to suck, just as no one teaches a sea turtle hatchling to move toward the ocean. Learning, like reflexes and instincts, allows an organism to adapt to its environment. But unlike instincts and reflexes, learned behaviors involve change and experience: learning is a relatively permanent change in behavior or knowledge that results from experience. In contrast to the innate behaviors discussed above, learning involves acquiring knowledge and skills through experience. Looking back at our surfing scenario, Julian will have to spend much more time training with his surfboard before he learns how to ride the waves like his father.
Learning to surf, as well as any complex learning process (e.g., learning about the discipline of psychology), involves a complex interaction of conscious and unconscious processes. Learning has traditionally been studied in terms of its simplest components—the associations our minds automatically make between events. Our minds have a natural tendency to connect events that occur closely together or in sequence. Associative learning occurs when an organism makes connections between stimuli or events that occur together in the environment. You will see that associative learning is central to all three basic learning processes discussed in this chapter; classical conditioning tends to involve unconscious processes, operant conditioning tends to involve conscious processes, and observational learning adds social and cognitive layers to all the basic associative processes, both conscious and unconscious. These learning processes will be discussed in detail later in the chapter, but it is helpful to have a brief overview of each as you begin to explore how learning is understood from a psychological perspective.
In classical conditioning, also known as Pavlovian conditioning, organisms learn to associate events—or stimuli—that repeatedly happen together. We experience this process throughout our daily lives. For example, you might see a flash of lightning in the sky during a storm and then hear a loud boom of thunder. The sound of the thunder naturally makes you jump (loud noises have that effect by reflex). Because lightning reliably predicts the impending boom of thunder, you may associate the two and jump when you see lightning. Psychological researchers study this associative process by focusing on what can be seen and measured—behaviors. Researchers ask if one stimulus triggers a reflex, can we train a different stimulus to trigger that same reflex? In operant conditioning, organisms learn, again, to associate events—a behavior and its consequence (reinforcement or punishment). A pleasant consequence encourages more of that behavior in the future, whereas a punishment deters the behavior. Imagine you are teaching your dog, Hodor, to sit. You tell Hodor to sit, and give him a treat when he does. After repeated experiences, Hodor begins to associate the act of sitting with receiving a treat. He learns that the consequence of sitting is that he gets a doggie biscuit (Figure \(\PageIndex{1}\)). Conversely, if the dog is punished when exhibiting a behavior, it becomes conditioned to avoid that behavior (e.g., receiving a small shock when crossing the boundary of an invisible electric fence).
Observational learning extends the effective range of both classical and operant conditioning. In contrast to classical and operant conditioning, in which learning occurs only through direct experience, observational learning is the process of watching others and then imitating what they do. A lot of learning among humans and other animals comes from observational learning. To get an idea of the extra effective range that observational learning brings, consider Ben and his son Julian from the introduction. How might observation help Julian learn to surf, as opposed to learning by trial and error alone? By watching his father, he can imitate the moves that bring success and avoid the moves that lead to failure. Can you think of something you have learned how to do after watching someone else?
All of the approaches covered in this chapter are part of a particular tradition in psychology, called behaviorism, which we discuss in the next section. However, these approaches do not represent the entire study of learning. Separate traditions of learning have taken shape within different fields of psychology, such as memory and cognition, so you will find that other chapters will round out your understanding of the topic. Over time these traditions tend to converge. For example, in this chapter you will see how cognition has come to play a larger role in behaviorism, whose more extreme adherents once insisted that behaviors are triggered by the environment with no intervening thought.
Summary
Instincts and reflexes are innate behaviors—they occur naturally and do not involve learning. In contrast, learning is a change in behavior or knowledge that results from experience. There are three main types of learning: classical conditioning, operant conditioning, and observational learning. Both classical and operant conditioning are forms of associative learning where associations are made between events that occur together. Observational learning is just as it sounds: learning by observing others.
Glossary
- associative learning
- form of learning that involves connecting certain stimuli or events that occur together in the environment (classical and operant conditioning)
- instinct
- unlearned knowledge, involving complex patterns of behavior; instincts are thought to be more prevalent in lower animals than in humans
- learning
- change in behavior or knowledge that is the result of experience
- reflex
- unlearned, automatic response by an organism to a stimulus in the environment
Contributors and Attributions
-
Rose M. Spielman with many significant contributors. The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the creative commons license and may not be reproduced without the prior and express written consent of Rice University. For questions regarding this license, please contact<EMAIL_ADDRESS>.Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. Download for free at<EMAIL_ADDRESS>.


20.5: Chemical Defenses - Complement System
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- Ying Liu
- City College of San Francisco
Learning Objectives
- Identify the three mechanisms that trigger complement activation
- Describe the outcome of complement activation
The Complement System
The complement system is a group of plasma protein mediators that can act as an innate nonspecific defense while also serving to connect innate and adaptive immunity (discussed in the next chapter). The complement system is composed of more than 30 proteins (including C1 through C9) that normally circulate as precursor proteins in blood. These precursor proteins become activated when stimulated or triggered by a variety of factors, including the presence of microorganisms. Complement proteins are considered part of innate nonspecific immunity because they are always present in the blood and tissue fluids, allowing them to be activated quickly. Also, when activated through the alternative pathway (described later in this section), complement proteins target pathogens in a nonspecific manner.
Complement Activation
The process by which circulating complement precursors become functional is called complement activation . This process is a cascade that can be triggered by one of three different mechanisms , known as the alternative, classical, and lectin pathways.
The alternative pathway is initiated by the spontaneous activation of the complement protein C3. The hydrolysis of C3 produces two products, C3a and C3b. When no invader microbes are present, C3b is very quickly degraded in a hydrolysis reaction using the water in the blood. However, if invading microbes are present, C3b attaches to the surface of these microbes. Once attached, C3b will recruit other complement proteins in a cascade (Figure \(\PageIndex{2}\)).
The classical pathway provides a more efficient mechanism of activating the complement cascade, but it depends upon the production of antibodies by the specific adaptive immune defenses. To initiate the classical pathway, a specific antibody must first bind to the pathogen to form an antibody-antigen complex . This activates the first protein in the complement cascade, the C1 complex. The C1 complex is a multipart protein complex, and each component participates in the full activation of the overall complex. Following recruitment and activation of the C1 complex, the remaining classical pathway complement proteins are recruited and activated in a cascading sequence (Figure \(\PageIndex{2}\)).
The lectin activation pathway is similar to the classical pathway, but it is triggered by the binding of mannose-binding lectin , an acute-phase protein, to carbohydrates on the microbial surface. Like other acute-phase proteins, lectins are produced by liver cells and are commonly upregulated in response to inflammatory signals received by the body during an infection (Figure \(\PageIndex{2}\)).
Outcome of Complement Activation
Although each complement activation pathway is initiated in a different way, they all provide the same protective outcomes: opsonization, inflammation, chemotaxis, and cytolysis . The term opsonization refers to the coating of a pathogen by a chemical substance (called an opsonin) that allows phagocytic cells to recognize, engulf, and destroy it more easily. Opsonins from the complement cascade include C1q, C3b, and C4b. Additional important opsonins include mannose-binding proteins and antibodies. The complement fragments C3a and C5a are well-characterized anaphylatoxins with potent proinflammatory functions. Anaphylatoxins activate mast cells, causing degranulation and the release of inflammatory chemical signals, including mediators that cause vasodilation and increased vascular permeability. C5a is also one of the most potent chemoattractants for neutrophils and other white blood cells, cellular defenses that will be discussed in the next section.
The complement proteins C6, C7, C8, and C9 assemble into a membrane attack complex (MAC) , which allows C9 to polymerize into pores in the membranes of gram-negative bacteria. These pores allow water, ions, and other molecules to move freely in and out of the targeted cells, eventually leading to cell lysis and death of the pathogen (Figure \(\PageIndex{2}\)). However, the MAC is only effective against gram-negative bacteria; it cannot penetrate the thick layer of peptidoglycan associated with cell walls of gram-positive bacteria.
Query \(\PageIndex{1}\)
Key Concepts and Summary
- The complement system involves numerous precursor proteins that circulate in plasma. These proteins become activated in a cascading sequence in the presence of microbes, resulting in the opsonization of pathogens, chemoattraction of leukocytes, induction of inflammation, and cytolysis through the formation of a membrane attack complex (MAC) .


5.1: Newton’s Three Laws
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Newton’s classical theory of physics is based on the three following laws:
- Law 1 : An object will remain in its state of motion, be it at rest or moving with constant velocity, unless a net external force is exerted on the object.
- Law 2 : An object’s acceleration is proportional to the net force exerted on the object , inversely proportional to the mass of the object, and in the same direction as the net force exerted on the object.
- Law 3 : If one object exerts a force on another object, the second object exerts a force on the first object that is equal in magnitude and opposite in direction.
The three statements above are sufficient to describe almost all of the natural phenomena that we experience in our lives. Concepts such as energy, center of mass, torque, etc, which you may have already encountered, are derived naturally from these three laws. In order to build models to describe specific experiments or observations using Newton’s Laws, one needs to understand the two main mathematical concepts that are introduced by the theory: force and mass. A few comments on each of the three laws are first provided before the concepts of force and mass are developed further.
Newton’s First Law
Newton’s First Law is often referred to as the law of inertia which was originally stated by Galileo. The first law is counter-intuitive, as our experience is that if you push a block on a table and let it go, it will eventually stop. Indeed, Aristotle proposed that the natural state of objects is to be at rest. As a result of Newton’s theory, we now understand that if you model a block sliding on a table, one must include a force of friction between the table and the block that acts to slow it down; a sliding block is thus not in a situation where no net external force is exerted on the object.
Newton’s First Law is useful in defining what we call an “inertial frame of reference”, which is a frame of reference in which Newton’s First Law holds true. A frame of reference can be thought of as a coordinate system which can be moving. For example, if a train is moving with constant velocity, we can consider the train as an inertial frame of reference since objects in the train would follow Newton’s First Law for observers that are in the train. If a train passenger placed an object on a table, they would observe that the object does not spontaneously start moving; if they slide an object on a frictionless table, they would observe that it keeps on sliding at constant velocity.
However, if the train is accelerating forwards, then an object placed on a frictionless table would appear, for observers in the train’s frame of reference, to be accelerating in the direction opposite to that of the train, and violate Newton’s First Law. An accelerating train is thus not an inertial frame of reference. To an observer on the ground, looking into the accelerating train through a window, the object placed on the table would appear to move with the same constant velocity as when it was placed on the table (the velocity of the train at the instant the object is placed on the table). In a similar way, when you are in a car, Newton’s First Law holds if the car is going at constant velocity, but if the car goes around a curve (and thus accelerates even its speed is constant), you will find that all objects in the car suddenly appear to be pushed towards the outside of the curve, in conflict with Newton’s First Law; this is because the accelerating car is not an inertial frame of reference and Newton’s First Law is thus not expected to hold.
Newton’s First Law thus allows us to define an inertial frame of reference; Newton’s Three Laws only hold in inertial frames of reference.
Exercise \(\PageIndex{1}\)
You are in an elevator accelerating upwards.
- The elevator is an inertial frame of reference.
- The elevator is not an inertial frame of reference.
- Answer
- B.
Newton’s Second Law
Newton’s Second Law is often written as a vector equation:
\[\begin{aligned} \sum \vec F = m\vec a\end{aligned}\]
where \(\sum \vec F\) is the vector sum of the forces exerted on an object, \(\vec a\) is the acceleration vector of the object, and \(m\) is the “inertial mass” of the object. As we will see, a force is represented by a vector, and the sum of the force vectors on an object is often called the “net force”. Recall that using vectors to write an equation is just a shorthand for writing the equation out for each component. In three dimensions, this would thus correspond to three independent scalar equations (one for each component of the force and acceleration vectors):
\[\begin{aligned} \sum F_x &= ma_x \\[4pt] \sum F_y &= ma_y \\[4pt] \sum F_z &= ma_z\end{aligned}\]
Newton’s Second Law is the foundation for Classical Physics, in which we seek to quantitatively describe the motion of any object. The motion of an object is fully specified by its acceleration as long as we know the position and velocity at a specific point in time. That is, by knowing the position and velocity of the object at a point in time and its acceleration, we can describe its motion both in the future and in the in past; we call Classical Physics a deterministic theory (as opposed to, say, Quantum Mechanics, which would only tell us the probability that a particle would be at some particular position in the future). The right-hand side of Newton’s Second Law thus contains the kinematic description of the object; if we know the acceleration, we know everything about the motion of the object.
The left-hand side of the equation contains all of the “dynamics” to describe the object; force is the tool that Newton introduced in order to be able to determine the acceleration of an object. Newton’s Second Law thus tells how to determine the kinematics of an object by using the concept of forces; it relates the dynamics to the kinematics. Having already covered kinematics, we will now focus on understanding dynamics and how to develop models that allow us to calculate the net force on an object. The inertial mass, \(m\) , is a specific property of an object that tells us how large an acceleration it will experience based on a given net force. Thus, objects with different masses will experience different accelerations if subject to the same net force.
Exercise \(\PageIndex{1}\)
Object 1 has twice the inertial mass of object 2. If both objects have the same acceleration vector.
- The net force on both objects is the same.
- The net force on object 1 is twice that on object 2.
- The net force on object 1 is half of that on object 2.
- Answer
- B.
Newton’s Third Law
Newton’s Third Law relates the forces that two objects exert on each other. It is important to understand that the forces that are mentioned in the Newton’s Third Law are exerted on different objects. If object A exerts a force on object B, then object B will also exert a force on object A. The two forces have the same magnitude but opposite directions. Sometimes, the forces are called “action” and “reaction” forces, although this is misleading, because it makes it sound like the reaction force is “in response to” some voluntary action force. However, inanimate objects can exert forces, and so this can lead to needless confusion as to which force is the reaction force.
It does not matter which force you choose to call the action (reaction) force. If a block is pushing down on a table (action force), then the table is pushing up on the block (reaction force). However, one could just as well say that the table is pushing up on the block (action force) so the block is pushing down on the table (reaction force). It does not matter which force you call the action force. This can be confusing, because if you choose to push on a wall (exerting an action force), then the wall exerts a force on you (the reaction force). If you choose not to push on the wall (exerting no force), then the wall does not exert the reaction force. This leads to people thinking that the reaction force is in response to an action force exerted by a sentient being, which is not the case. You can call the force that you choose to exert on the wall the reaction force and Newton’s Laws will still work just as well!
Newton’s Third law often leads to confusion when Newton’s Second Law is applied. Recall that Newton’s Second Law involves the sum of the forces on a particular object (the “net force” on that object). The two forces that are mentioned in Newton’s Third Law are not exerted on the same object , so they would never appear together in the sum of the forces from Newton’s Second Law, and they never cancel each other.
Exercise \(\PageIndex{3}\)
You push a heavy block in the North direction. The block is twice as heavy as you are. Which statement is true?
- The block exerts half of the force on you, in the North direction.
- The block exerts the same force on you, but in the South direction.
- The block exerts double of the force on you, in the South direction.
- The block is inanimate and thus does not exert a force on you.
- Answer
- B.


38.19: Muscle Contraction and Locomotion - Excitation–Contraction Coupling
- Explain the process of excitation-contraction coupling and the role of neurotransmitters
Excitation–Contraction Coupling
Excitation–contraction coupling is the physiological process of converting an electrical stimulus to a mechanical response. It is the link (transduction) between the action potential generated in the sarcolemma and the start of a muscle contraction.
Communication between Nerves and Muscles
A neural signal is the electrical trigger for calcium release from the sarcoplasmic reticulum into the sarcoplasm. Each skeletal muscle fiber is controlled by a motor neuron, which conducts signals from the brain or spinal cord to the muscle. Electrical signals called action potentials travel along the neuron’s axon, which branches through the muscle, connecting to individual muscle fibers at a neuromuscular junction. The area of the sarcolemma on the muscle fiber that interacts with the neuron is called the motor-end plate. The end of the neuron’s axon is called the synaptic terminal; it does not actually contact the motor-end plate. A small space called the synaptic cleft separates the synaptic terminal from the motor-end plate.
Because neuron axons do not directly contact the motor-end plate, communication occurs between nerves and muscles through neurotransmitters. Neuron action potentials cause the release of neurotransmitters from the synaptic terminal into the synaptic cleft, where they can then diffuse across the synaptic cleft and bind to a receptor molecule on the motor end plate. The motor end plate possesses junctional folds: folds in the sarcolemma that create a large surface area for the neurotransmitter to bind to receptors. The receptors are sodium channels that open to allow the passage of Na + into the cell when they receive neurotransmitter signal.
Depolarization in the Sarcolemma
Acetylcholine (ACh) is a neurotransmitter released by motor neurons that binds to receptors in the motor end plate. Neurotransmitter release occurs when an action potential travels down the motor neuron’s axon, resulting in altered permeability of the synaptic terminal membrane and an influx of calcium. The Ca 2+ ions allow synaptic vesicles to move to and bind with the presynaptic membrane (on the neuron) and release neurotransmitter from the vesicles into the synaptic cleft. Once released by the synaptic terminal, ACh diffuses across the synaptic cleft to the motor end plate, where it binds with ACh receptors.
As a neurotransmitter binds, these ion channels open, and Na + ions cross the membrane into the muscle cell. This reduces the voltage difference between the inside and outside of the cell, which is called depolarization. As ACh binds at the motor end plate, this depolarization is called an end-plate potential. The depolarization then spreads along the sarcolemma and down the T tubules, creating an action potential. The action potential triggers the sarcoplasmic reticulum to release of Ca 2+ , which activate troponin and stimulate muscle contraction.
ACh is broken down by the enzyme acetylcholinesterase (AChE) into acetyl and choline. AChE resides in the synaptic cleft, breaking down ACh so that it does not remain bound to ACh receptors, which would cause unwanted extended muscle contraction.
Key Points
- A motor neuron connects to a muscle at the neuromuscular junction, where a synaptic terminal forms a synaptic cleft with a motor-end plate.
- The neurotransmitter acetylcholine diffuses across the synaptic cleft, causing the depolarization of the sarcolemma.
- The depolarization of the sarcolemma stimulates the sarcoplasmic reticulum to release Ca 2+ , which causes the muscle to contract.
Key Terms
- motor-end plate : postjunctional folds which increase the surface area of the membrane (and acetylcholine receptors) exposed to the synaptic cleft
- sarcolemma : a thin cell membrane that surrounds a striated muscle fiber
- acetylcholinesterase : an enzyme that catalyzes the hydrolysis of the neurotransmitter acetylcholine into choline and acetic acid


7.3: Nuclear Binding Energy
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Learning Objectives
By the end of this section, you will be able to:
- Calculate the mass defect and binding energy for a wide range of nuclei
- Use a graph of binding energy per nucleon (BEN) versus mass number ( A ) graph to assess the relative stability of a nucleus
- Compare the binding energy of a nucleon in a nucleus to the ionization energy of an electron in an atom
The forces that bind nucleons together in an atomic nucleus are much greater than those that bind an electron to an atom through electrostatic attraction. This is evident by the relative sizes of the atomic nucleus and the atom (\(10^{-15}\) and \(10^{-10}\)m, respectively). The energy required to pry a nucleon from the nucleus is therefore much larger than that required to remove (or ionize) an electron in an atom. In general, all nuclear changes involve large amounts of energy per particle undergoing the reaction. This has numerous practical applications.
Mass Defect
According to nuclear particle experiments, the total mass of a nucleus \((m_{nuc})\) is less than the sum of the masses of its constituent nucleons (protons and neutrons). The mass difference, or mass defect , is given by
\[\Delta m = Zm_p + (A - Z)m_n - m_{nuc} \label{mass defect} \]
where \(Zm_p\) is the total mass of the protons, \((A - Z)m_n\) is the total mass of the neutrons, and \(m_{nuc}\) is the mass of the nucleus. According to Einstein’s special theory of relativity, mass is a measure of the total energy of a system (\(E = mc^2\)). Thus, the total energy of a nucleus is less than the sum of the energies of its constituent nucleons. The formation of a nucleus from a system of isolated protons and neutrons is therefore an exothermic reaction—meaning that it releases energy. The energy emitted, or radiated, in this process is \((\Delta m)c^2\).
Now imagine this process occurs in reverse. Instead of forming a nucleus, energy is put into the system to break apart the nucleus (Figure \(\PageIndex{1}\)). The amount of energy required is called the total binding energy (BE) , \(E_b\).
Definition: Binding Energy
The binding energy is equal to the amount of energy released in forming the nucleus, and is therefore given by
\[E_b = (\Delta m)c^2. \label{BE} \]
Experimental results indicate that the binding energy for a nucleus with mass number \(A > 8\) is roughly proportional to the total number of nucleons in the nucleus, A . The binding energy of a magnesium nucleus \((^{24}Mg)\), for example, is approximately two times greater than for the carbon nucleus \((^{12}C)\).
Example \(\PageIndex{1}\): Mass Defect and Binding Energy of the Deuteron
Calculate the mass defect and the binding energy of the deuteron. The mass of the deuteron is \(m_D = 3.34359 \times 10^{-27}kg\) or \(1875.61 \, MeV/c^2\).
Solution
For the deuteron \(Z=1\) and \(A=2\). From Equation \ref{mass defect}, the mass defect for the deuteron is
\[\begin{align*} \Delta m &= m_p + m_n - m_D \\[4pt] &= 938.28 \, MeV/c^2 + 939.57 \, MeV/c^2 - 1875.61 \, MeV/c^2 \\[4pt] &= 2.24 \, MeV/c^2. \end{align*} \nonumber \]
The binding energy of the deuteron is then
\[\begin{align*} E_b &= (\Delta m)c^2 \\[4pt] &= (2.24 \, MeV/c^2)(c^2) \\[4pt] &= 2.24 \, MeV. \end{align*} \nonumber \]
Over two million electron volts are needed to break apart a deuteron into a proton and a neutron. This very large value indicates the great strength of the nuclear force. By comparison, the greatest amount of energy required to liberate an electron bound to a hydrogen atom by an attractive Coulomb force (an electromagnetic force) is about 10 eV.
Graph of Binding Energy per Nucleon
In nuclear physics, one of the most important experimental quantities is the binding energy per nucleon (BEN) , which is defined by
\[BEN = \dfrac{E_b}{A} \label{BEN} \]
This quantity is the average energy required to remove an individual nucleon from a nucleus—analogous to the ionization energy of an electron in an atom. If the BEN is relatively large, the nucleus is relatively stable. BEN values are estimated from nuclear scattering experiments.
A graph of binding energy per nucleon versus atomic number A is given in Figure \(\PageIndex{2}\). This graph is considered by many physicists to be one of the most important graphs in physics. Two notes are in order. First, typical BEN values range from 6–10 MeV, with an average value of about 8 MeV. In other words, it takes several million electron volts to pry a nucleon from a typical nucleus, as compared to just 13.6 eV to ionize an electron in the ground state of hydrogen. This is why nuclear force is referred to as the “strong” nuclear force.
Second, the graph rises at low A , peaks very near iron \((Fe, \, A = 56)\), and then tapers off at high \(A\). The peak value suggests that the iron nucleus is the most stable nucleus in nature (it is also why nuclear fusion in the cores of stars ends with Fe). The reason the graph rises and tapers off has to do with competing forces in the nucleus. At low values of \(A\), attractive nuclear forces between nucleons dominate over repulsive electrostatic forces between protons. But at high values of \(A\), repulsive electrostatic forces between forces begin to dominate, and these forces tend to break apart the nucleus rather than hold it together.
As we will see, the BEN-versus- A graph implies that nuclei divided or combined release an enormous amount of energy. This is the basis for a wide range of phenomena, from the production of electricity at a nuclear power plant to sunlight.
Example \(\PageIndex{2}\): Tightly Bound Alpha Nuclides
Calculate the binding energy per nucleon of an \(^4He \, (\alpha \, particle)\).
Strategy
Determine the total binding energy (BE) using the equation \(BE = (\Delta m)c^2\), where \(\Delta m\) is the mass defect. The binding energy per nucleon (BEN) is BE divided by \(A\) (Equation \ref{BEN}).
Solution
For \(^4He\), we have \(Z = N = 2\). The total binding energy (Equation \ref{BE}) is
\[BE = {[2m_p + 2m_n] - m(^4He)}c^2. \nonumber \]
These masses are \(m(^4He) = 4.002602 \, u\), \(m_p = 1.007825 \, u\), and \(m_n = 1.008665 \, u\). Thus we have
\[BE = (0.030378 \, u)c^2. \nonumber \]
Noting that \(1 \, u = 931.5 \, MeV/c^2\), we find
\[\begin{align*} BE &= (0.030378)(931.5 \, MeV/c^2)c^2 \\[4pt] &= 28.3 \, MeV. \end{align*} \nonumber \]
Since \(A = 4\), the total binding energy per nucleon (Equation \ref{BEN}) is
\[BEN = 7.07 \, MeV/nucleon. \nonumber \]
Significance
Notice that the binding energy per nucleon for \(^4He\) is much greater than for the hydrogen isotopes (\(\approx 3 \, MeV/nucleon\)). Therefore, helium nuclei cannot break down hydrogen isotopes without energy being put into the system.
Exercise \(\PageIndex{2}\)
If the binding energy per nucleon is large, does this make it harder or easier to strip off a nucleon from a nucleus?
- Answer
-
harder


4.12: Benefits of Diversity
- Discuss the benefits of a diverse workforce
UC Berkeley’s Greater Good Science Center’s (GGSC) definition of diversity captures not only that essential element of difference but why it matters. To quote: “‘diversity’ refers to both an obvious fact of human life—namely, that there are many different kinds of people—and the idea that this diversity drives cultural, economic, and social vitality and innovation.’” [1] From a human resource management standpoint, it’s important to note that diversity benefits both the organization and individuals. GGSC cites research indicating that “individuals thrive when they are able to tolerate and embrace the diversity of the world.” Of course, the opposite is also true: intolerance undermines our well-being.
In the Executive Summary of their 2018 “Delivering through Diversity” report, McKinsey & Company consultants Vivian Hunt, Sara Prince, Sundiatu Dixon-Fyle and Lareina Yee observe that “While social justice, legal compliance, or maintaining industry-standard employee environment protocols is typically the initial impetus behind these efforts, many successful companies regard I&D [inclusion & diversity] as a source of competitive advantage, and specifically as a key enabler of growth.” [2] In this follow-up to prior research conducted in 2015, the authors found the business case for diversity and inclusion remains compelling. Specific findings: [3]
- Diversity drives business performance. There is a “statistically significant correlation between a more diverse leadership team and financial outperformance.”
- Executive diversity (gender++) matters. “Companies in the top-quartile for gender diversity on executive teams were 21% more likely to outperform on profitability and 27% more likely to have superior value creation.” The authors note that the connection between executive diversity and performance isn’t limited to gender. “Companies in the top-quartile for ethnic/cultural diversity on executive teams were 33% more likely to have industry-leading profitability.” The authors conclude that executive diversity in “the myriad ways in which diversity exists beyond gender (e.g., LGBTQ+, age/generation, international experience) can be a key differentiator among companies.ƒ”
- Lack of diversity impairs business results. As the authors phrase it, “There is a penalty for opting out [of diversity].” Specifically, “companies in the bottom quartile for both gender and ethnic/cultural diversity were 29% less likely to achieve above-average profitability than were all other companies in our data set.”
For human resource management, in particular, it’s important to understand what’s driving higher performance.
The authors believe that the positive relationship between I&D and performance is due to the fact that “more diverse companies are better able to attract top talent; to improve their customer orientation, employee satisfaction, and decision making; and to secure their license to operate.” To expand on those findings, here are seven benefits drawn from Hult International Business School’s blog: [4]
- Greater creativity and innovation—diversity of thought—for example, different experiences, perspectives and cognitive styles—can stimulate creativity and drive innovation. Hult blogger Katie Reynolds notes that “cosmetic giant L’Oréal attributes much of its impressive success in emerging markets to its multicultural product development teams.” The Harvard Business Review article she references, “ L’Oréal Masters Multiculturalism ,” is a recommended read for any student interested in international business.
- Improved competitive positioning—“local knowledge”—everything from local laws and customs to connections, language and cultural fluency—can increase the probability of success when entering a new country or region.
- Improved marketing effectiveness—having an understanding of the nuances of culture and language is a prerequisite for developing appropriate products and marketing materials. The list of gaffes is endless…and the financial and brand impact of errors can be significant, from a line of Nike Air shoes that were perceived to be disrespectful of Allah to the poor Chinese translation of KFC’s “Finger lickin’ good tagline: “so tasty, you’ll eat your fingers off!”
- Improved talent acquisition & retention—this is particularly critical in a competitive job market: embracing diversity not only increases the talent pool, it improves candidate attraction and retention. A Glassdoor survey found that 67% of job seekers indicated that diversity was an important factor when evaluating companies and job offers. Reynolds also cites HR.com research that indicates diversity, including diversity of gender, religion, and ethnicity, improves retention.
- Increased organizational adaptability—hiring individuals with a broader base of skills and experience and cognitive styles will likely be more effective in developing new products and services, supporting a diverse client base and will allow an organization to anticipate and leverage market and socio-cultural or political developments/opportunities.
- Greater productivity—research has shown that the range of experience, expertise and cognitive styles that are implicit in a diverse workforce improve complex problem-solving, innovation and productivity. Additional benefit: responsiveness—A study conducted in Australia found that “when diversity is recognised and employees feel included they have a better responsiveness to changing customer needs.” [5]
- Greater personal and professional growth—learning to working across and leverage differences can be an enriching experience and an opportunity to build a diverse network and develop a range of high-value soft skills including communication, empathy, collaborative problem-solving and multicultural awareness. To that point, GGSC reports that a study published in Psychological Science found that “social and emotional intelligence rises as we interact with more kinds of people.” [6]
- " Diversity Defined: What is Diversity? " Greater Good Magazine . Accessed September 14, 2019. ↵
- Hunt, Vivian, Sara Prince, Sundiatu Dixon-Fyle, and Lareina Yee. " Delivering Through Diversity. " McKinsey & Company. January 2018. Accessed September 14, 2019. ↵
- Ibid. ↵
- Reynolds, Katie. " 13 benefits and Challenges of Cultural Diversity in the Workplace ." Hult International Business School. February 2019. Accessed September 14, 2019. ↵
- Grey, Justin.  " MyBusiness. January 21, 2013. Accessed September 14, 2019. ↵
- " Diversity Defined: Why Practice It? " Greater Good Magazine. Accessed September 14, 2019. ↵
Contributors and Attributions
- wocintech (microsoft) - 134. Authored by : WOCinTech Chat. Provided by : Flickr. Located at : https://flic.kr/p/FsLtEA . License : CC BY: Attribution
- Untitled. Authored by : Gerd Altmann. Provided by : Pixabay. Located at : pixabay.com/illustrations/teamwork-team-gear-gears-drive-2198961/. License : CC0: No Rights Reserved . License Terms : Pixabay License


3.8: Safe Circuit Design
As far as the voltage source and load are concerned, grounding makes no difference at all. It exists purely for the sake of personnel safety, by guaranteeing that at least one point in the circuit will be safe to touch (zero voltage to ground). The “Hot” side of the circuit, named for its potential for shock hazard, will be dangerous to touch unless voltage is secured by proper disconnection from the source (ideally, using a systematic lock-out/tag-out procedure).
This imbalance of hazard between the two conductors in a simple power circuit is important to understand. The following series of illustrations are based on common household wiring systems (using DC voltage sources rather than AC for simplicity).
If we take a look at a simple, household electrical appliance such as a toaster with a conductive metal case, we can see that there should be no shock hazard when it is operating properly. The wires conducting power to the toaster’s heating element are insulated from touching the metal case (and each other) by rubber or plastic.
However, if one of the wires inside the toaster were to accidentally come in contact with the metal case, the case will be made electrically common to the wire, and touching the case will be just as hazardous as touching the wire bare. Whether or not this presents a shock hazard depends on which wire accidentally touches:
If the “hot” wire contacts the case, it places the user of the toaster in danger. On the other hand, if the neutral wire contacts the case, there is no danger of shock:
To help ensure that the former failure is less likely than the latter, engineers try to design appliances in such a way as to minimize hot conductor contact with the case. Ideally, of course, you don’t want either wire accidentally coming in contact with the conductive case of the appliance, but there are usually ways to design the layout of the parts to make accidental contact less likely for one wire than for the other. However, this preventative measure is effective only if power plug polarity can be guaranteed. If the plug can be reversed, then the conductor more likely to contact the case might very well be the “hot” one:
Appliances designed this way usually come with “polarized” plugs, one prong of the plug being slightly narrower than the other. Power receptacles are also designed like this, one slot being narrower than the other. Consequently, the plug cannot be inserted “backwards,” and conductor identity inside the appliance can be guaranteed. Remember that this has no effect whatsoever on the basic function of the appliance: its strictly for the sake of user safety.
Some engineers address the safety issue simply by making the outside case of the appliance nonconductive. Such appliances are called double-insulated , since the insulating case serves as a second layer of insulation above and beyond that of the conductors themselves. If a wire inside the appliance accidently comes in contact with the case, there is no danger presented to the user of the appliance.
Other engineers tackle the problem of safety by maintaining a conductive case, but using a third conductor to firmly connect that case to ground:
The third prong on the power cord provides a direct electrical connection from the appliance case to earth ground, making the two points electrically common with each other. If they’re electrically common, then there cannot be any voltage dropped between them. At least, that’s how it is supposed to work. If the hot conductor accidently touches the metal appliance case, it will create a direct short-circuit back to the voltage source through the ground wire, tripping any overcurrent protection devices. The user of the appliance will remain safe.
This is why its so important never to cut the third prong off a power plug when trying to fit it into a two-prong receptacle. If this is done, there will be no grounding of the appliance case to keep the user(s) safe. The appliance will still function properly, but if there is an internal fault bringing the hot wire in contact with the case, the results can be deadly. If a two-prong receptacle must be used, a two- to three-prong receptacle adapter can be installed with a grounding wire attached to the receptacle’s grounded cover screw. This will maintain the safety of the grounded appliance while plugged in to this type of receptacle.
Electrically safe engineering doesn’t necessarily end at the load, however. A final safeguard against electrical shock can be arranged on the power supply side of the circuit rather than the appliance itself. This safeguard is called ground-fault detection , and it works like this:
In a properly functioning appliance (shown above), the current measured through the hot conductor should be exactly equal to the current through the neutral conductor, because there’s only one path for electrons to flow in the circuit. With no fault inside the appliance, there is no connection between circuit conductors and the person touching the case, and therefore no shock.
If, however, the hot wire accidentally contacts the metal case, there will be current through the person touching the case. The presence of a shock current will be manifested as a difference of current between the two power conductors at the receptacle:
This difference in current between the “hot” and “neutral” conductors will only exist if there is current through the ground connection, meaning that there is a fault in the system. Therefore, such a current difference can be used as a way to detect a fault condition. If a device is set up to measure this difference of current between the two power conductors, a detection of current imbalance can be used to trigger the opening of a disconnect switch, thus cutting power off and preventing serious shock:
Such devices are called Ground Fault Current Interruptors , or GFCIs for short. Outside North America, the GFCI is variously known as a safety switch, a residual current device (RCD), an RCBO or RCD/MCB if combined with a miniature circuit breaker, or earth leakage circuit breaker (ELCB). They are compact enough to be built into a power receptacle. These receptacles are easily identified by their distinctive “Test” and “Reset” buttons. The big advantage with using this approach to ensure safety is that it works regardless of the appliance’s design. Of course, using a double-insulated or grounded appliance in addition to a GFCI receptacle would be better yet, but its comforting to know that something can be done to improve safety above and beyond the design and condition of the appliance.
The arc fault circuit interrupter (AFCI) , a circuit breaker designed to prevent fires, is designed to open on intermittent resistive short circuits. For example, a normal 15 A breaker is designed to open circuit quickly if loaded well beyond the 15 A rating, more slowly a little beyond the rating. While this protects against direct shorts and several seconds of overload, respectively, it does not protect against arcs– similar to arc-welding. An arc is a highly variable load, repetitively peaking at over 70 A, open circuiting with alternating current zero-crossings. Though, the average current is not enough to trip a standard breaker, it is enough to start a fire. This arc could be created by a metalic short circuit which burns the metal open, leaving a resistive sputtering plasma of ionized gases.
The AFCI contains electronic circuitry to sense this intermittent resistive short circuit. It protects against both hot to neutral and hot to ground arcs. The AFCI does not protect against personal shock hazards like a GFCI does. Thus, GFCIs still need to be installed in kitchen, bath, and outdoors circuits. Since the AFCI often trips upon starting large motors, and more generally on brushed motors, its installation is limited to bedroom circuits by the U.S. National Electrical code. Use of the AFCI should reduce the number of electrical fires. However, nuisance-trips when running appliances with motors on AFCI circuits is a problem.
Review
- Power systems often have one side of the voltage supply connected to earth ground to ensure safety at that point.
- The “grounded” conductor in a power system is called the neutral conductor, while the ungrounded conductor is called the hot .
- Grounding in power systems exists for the sake of personnel safety, not the operation of the load(s).
- Electrical safety of an appliance or other load can be improved by good engineering: polarized plugs, double insulation, and three-prong “grounding” plugs are all ways that safety can be maximized on the load side.
- Ground Fault Current Interruptors (GFCIs) work by sensing a difference in current between the two conductors supplying power to the load. There should be no difference in current at all. Any difference means that current must be entering or exiting the load by some means other than the two main conductors, which is not good. A significant current difference will automatically open a disconnecting switch mechanism, cutting power off completely.