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1438_38 | As the Blue prepare to invade the Iron in a last-ditch attempt at ending the war, Iron Man tracks down Jen's position and flies to rescue her. He finds her, but his armor is neutralized and stripped from him. Tony is brought to Black Panther who reveals himself as the Skrull Queen Veranke. Veranke tells him that she is the cause of every single failed attempt at reaching peace in a part of a plan to benefit from the never-ending war. Iron Man uses additional weaponry that was not in his armor to free himself, fend off the Skrull guards, and break She-Hulk free from her cage. Meanwhile, the Blue invade the Iron while General America prepares to detonate a bomb derived from Project Bellcurve. |
1438_39 | As the conflict escalates, Iron Man is able to reach General America and reveal that Bucky is a Skrull, prompting General America to accept a telepathic 'update' from Emma Frost that confirms that the Skrulls have manipulated the conflict for years. Accepting their mutual responsibility for the situation, Rogers and Stark sacrifice themselves to detonate the Bellcurve bomb. The blast depowers the superhumans and reverts the Skrulls to their true state. A few months later, a powerless Peter and Jennifer are shown discussing the tentative truce that has been formed between the two sides, and wonder whether Stark and Rogers knew that peace would be the result of their sacrifice.
Civil War II (2016) |
1438_40 | A direct sequel to the original series debuted in June 2016, written by Brian Michael Bendis and drawn by David Marquez. Unlike the previous story and the film, the conflict in this storyline is not about issues of government registration; instead, a new Inhuman, Ulysses, emerges with the ability to see predictions about the future. This results in conflict emerging between heroes led by Iron Man and Captain Marvel respectively, Stark favoring self-determination and concerned about the prospects of coming to depend on the visions while Danvers feels that his visions represent a potentially valuable asset. |
1438_41 | Reception
At the time of its release, Civil War received mixed reviews. Comic Book Round Up gave the series an average rating of 6.5.
According to a scholarly analysis presented at the 2007 Comic-Con International, this story's conflict is a natural outgrowth of what psychologist Erich Fromm called "the basic human dilemma", the conflicting desires for both security and freedom, and "character motivations on both sides arise from positive human qualities because Fromm's image of human nature is ultimately optimistic, holding that people on either side are struggling to find what is best for all".
However, over time, Civil War has become more well received. IGN ranked it as one of the greatest Comic Book Events.
Tie-ins
(This list is in read order)
Road To Civil War
Amazing Spider-Man #529
Amazing Spider-Man #530
Amazing Spider-Man #531
New Avengers: Illuminati Special #1
Fantastic Four #536
Fantastic Four #537
Civil War |
1438_42 | Civil War: Opening Shot Sketchbook
Civil War #1
Wolverine #42
Wolverine #43
Wolverine #44
Wolverine #45
She-Hulk (2nd series) #8
X-Factor #8
New Avengers #21
New Avengers #22
Civil War: Front Line #1
Civil War #2
Amazing Spider-Man #532
Amazing Spider-Man #533
Thunderbolts #103
Civil War: Front Line #2
Fantastic Four #538
Fantastic Four #539
Amazing Spider-Man #534
Civil War: Front Line #3
Iron Man Vol. 4 #13
Ms. Marvel #6
Ms. Marvel #7
Ms. Marvel #8
Thunderbolts #104
Thunderbolts #105
Black Panther #18
Black Panther #22
Civil War: X-Men #1
Heroes for Hire #1
Civil War #3
Civil War #4
Civil War: X-Men #2
Civil War: X-Men #3
Civil War: X-Men #4
Black Panther #23
Cable & Deadpool #30
Cable & Deadpool #31
Cable & Deadpool #32
Civil War: Young Avengers & Runaways #1
Civil War: Young Avengers & Runaways #2
Civil War: Young Avengers & Runaways #3
Civil War: Young Avengers & Runaways #4
Daily Bugle Special Edition: Civil War
Civil War: Front Line #4
X-Factor #9
Civil War: Front Line #5 |
1438_43 | Heroes for Hire #2
Heroes for Hire #3
New Avengers #23
Iron Man / Captain America: Casualties of War
Civil War Files
Wolverine #46
Wolverine #47
Captain America (5th series) #22
Captain America (5th series) #23
Captain America (5th series) #24
Civil War: Front Line #6
Civil War: Front Line #7
Civil War: Choosing Sides
New Avengers #24
Fantastic Four #540
Amazing Spider-Man #535
Civil War #5
Amazing Spider-Man #536
Punisher: War Journal #1
New Avengers #25
Civil War: Front Line #8
Wolverine #48
Civil War: War Crimes
Iron Man #14
Fantastic Four #541
Fantastic Four #542
Winter Soldier: Winter Kills
Blade #5
Civil War: The Return
Black Panther #24
Moon Knight #7
Amazing Spider-Man #537
Civil War #6
Civil War #7
Black Panther #25
Amazing Spider-Man #538
Civil War: The Confession
Civil War: The Initiative
Civil War: Battle Damage Report
Civil War Poster Book
Fallen Son: The Death of Captain America
Ghost Rider #8-11
Marvel Spotlight: Civil War Aftermath |
1438_44 | Marvel Spotlight: Captain America Remembered |
1438_45 | Related but not listed
The 2006 Eternals relaunch has the Civil War play a fairly present background in the setting with Sprite appearing in pro-registration PSAs. In issue #3, Iron Man reminds Sersi to register. In issue #6, Iron Man and Hank Pym try to get the Eternals to register again, but they refuse. In the end, Zuras explains that the Eternals have no desire to meddle with humanity, and will stay out of their affairs, which Iron Man concedes as a fair compromise.
Daredevil #87 leads into Civil War: Choosing Sides (one-shot).
New X-Men #28 and She-Hulk #9 are indirectly, but strongly involved.
In Black Panther #19-20 "World Tour" Black Panther meets with Doctor Doom, then the Inhumans, to discuss the Civil War (these are not listed as official tie-ins due to a marketing error). |
1438_46 | Marvel Comics Presents (vol. 2) #12 involves a patsy attempt to get Man-Thing to register with the government. The story was published late (October 2008 cover date), during Secret Invasion and the same month as Marvel Zombies 3, in which Man-Thing also appeared.
The cover of Nextwave: Agents of H.A.T.E. #11 features a Civil War parody cover including a plaid background, the words "Not part of a Marvel Comics event," and Aaron Stack holding up a card reading "Mark Millar licks goats."
Spider-Man and Power Pack #3 (March 2007) includes a parody entitled "Civil Wards," written by Marc Sumerak and illustrated by Chris Giarrusso.
The final issue of Robert Kirkman's Marvel Team-Up opens with Peter Parker getting ready to travel to Washington with Iron Man.
The third issue of the 2006 Union Jack miniseries also mentions Tony Stark and Peter Parker's trip to Washington. |
1438_47 | Incredible Hulk #100 includes a 12-page backup story dealing with Mr. Fantastic's involvement with the Thor clone, and the repercussions of the Illuminati having exiled the Hulk into space.
In Annihilation #4, the former Earth hero Nova is aware of the Civil War and is disappointed with the actions the heroes have taken, as they are not united against the threat of Annihilus.
In Friendly Neighborhood Spider-Man #6-13, Spider-Man is seen wearing the new suit he got in The Road to Civil War.
Friendly Neighborhood Spider-Man #14-16
New X-Men #29-31
Thunderbolts #106-108
In Sensational Spider-Man #26-27, Spider-Man is seen wearing the new suit he got in The Road to Civil War.
In Sensational Spider-Man #28-34, Spider-Man deals with the aftermath of revealing his identity.
Captain America (5th ed.) #25 is subtitled Civil War Epilogue.
Fantastic Four #543 is subtitled Civil War Epilogue. |
1438_48 | Punisher: War Journal (2nd ed.) #2 and #3 are direct Civil War tie ins (prior to Civil War #6).
Moon Knight (5th ed.) #8 and #9 are direct Civil War tie ins.
Civil War: Front Lines #9-11 are direct Civil War tie ins. |
1438_49 | Collected Editions
Oversized Hardcovers
Trade Paperbacks
{*
In other media |
1438_50 | Novels
Marvel adapted Civil War into a prose hardcover novel in July 2012 as the first of a series of four novels adapting some of Marvel's most significant fictional events. It was written by Stuart Moore, the writer of Namor: The First Mutant. The book expanded on the story and set the events during Barack Obama's first term in office, rather than George W. Bush's last term; Tony Stark makes reference to the Affordable Care Act when speaking to Spider-Man in the first chapter of the novel. The novel is set in the alternate timeline created by the controversial storyline "One More Day" and detailed in "One Moment in Time", as Spider-Man is depicted as never having married Mary Jane Watson, having never arrived on the day of their wedding. In the original comics version, Civil War was a lead-in to "One More Day", depicting May Parker's assassination on the orders of Wilson Fisk near the end of the main Civil War storyline.
Film |
1438_51 | The 2016 film Captain America: Civil War was a cinematic treatment of the story, albeit focusing more on the issue of government control rather than public knowledge of secret identities: these matters were also being escalated by the interference and manipulation of Helmut Zemo as his plan for revenge against the Avengers' role in Ultron's assault and the deaths of Zemo's family. The movie version of Civil War also differs from the comic substantially, former U.S Army General Thaddeus Ross as the U.S Secretary of State is involved in the registration debacle instead of S.H.I.E.L.D and Maria Hill as the former was dismantled in Captain America: The Winter Soldier and the latter's whereabouts are unknown at that point or is presumably in hiding with Nick Fury, with the fate of Bucky Barnes becoming a key element of the war after he is framed for the assassination of the Black Panther's father, the king of Wakanda. As in the comics, Captain America and Iron Man are the respective |
1438_52 | leaders of the anti-registration and pro-registration sides of the conflicts, with Cap's side including the Falcon, Bucky, Ant-Man, Hawkeye, and the Scarlet Witch, and Iron Man's side being Black Widow, War Machine, the Black Panther, Spider-Man and the Vision. Stark and Rogers reconcile after realizing the truth of the king's assassination, but it is short lived as Zemo reveals Barnes' role in Stark's parents' deaths, and that Rogers kept the truth from him. An enraged Stark attacks both Rogers and Barnes, and the fight culminates with Rogers abandoning his shield and identity and escaping with Barnes, becoming a fugitive in the process. The film concludes with Cap's side seeking asylum in Wakanda after the Black Panther recognizes that he was wrong to target Bucky. The latter is then put in a cryogenetic sleep. Black Widow goes on the run after betraying Stark's side to help Rogers find the instigator of their fight, and War Machine is left crippled after injuries sustained in the |
1438_53 | final battle. |
1438_54 | Later in the 2018 film Avengers: Infinity War it was revealed that Hawkeye and Ant-Man made deals with Ross to be placed in house arrest, so they could be with their families. The impact of the Civil War is also heavily felt throughout the film as the Avengers' disunity and Rogers and Stark still being on bad terms, left them vulnerable to Thanos' invasion and the Blip. |
1438_55 | Television
A different variation of the Civil War storyline closely resembling Civil War II as it features Iron Man and Captain Marvel in opposition to each other was adapted in the four-part Season finale of Avengers: Ultron Revolution. In this version of the storyline, the Registration Act targets new Inhumans, and teams of Avengers come into conflict over the issue, as in other adaptations. It is revealed in Part 3, however, that the Inhuman Registration Act is actually part of a plan by Ultron (disguised as Truman Marsh) to begin the Ultron Revolution by manipulating humans and Inhumans into destroying each other, which is foiled by the combined efforts of the Avengers. |
1438_56 | Video games
The comic is adapted into Marvel: Ultimate Alliance 2. While the storyline remains relatively faithful to the original comic, it takes a different path halfway through the game, as the act is briefly suspended for the heroes to deal with a crisis involving the nanite network used to control supervillains manifesting a form of sentience. In the game, the player gets to choose whether to side with Pro or Anti-Registration- with Captain America, Luke Cage and Iron Fist 'locked' into Anti-Registration and Iron Man, Mister Fantastic and Songbird in Pro-Registration- which affects the story's progression, characters they interact with, and the story's ending. Spider-Man and Wolverine are however playable on both sides. |
1438_57 | In Marvel vs. Capcom 3: Fate of Two Worlds, Iron Man and Captain America reference the event if they are pitted against each other. The player also receives an achievement titled "Whose Side are You On?" if Iron Man defeats Captain America or vice versa in an online match.
In Marvel: Contest of Champions, a special storyline featured elements of the Civil War, as the apparent death of the Collector causes Iron Man and Captain America to become divided over what action they should take with the Iso-Spheres that must be collected in the game. This storyline also introduces a special player in the form of the Civil Warrior, who is identified as a version of Steve Rogers who witnessed so much death in the final battle of the Civil War that he adopted some of Tony Stark's armor and dedicated himself to preventing such a catastrophe ever again. |
1438_58 | References
External links
Civil War Covers
Civil War Review | BGN Favourable review of Civil War
Captain America storylines
Comics set in New York City
Fictional wars
Harvey Award winners for Best Single Issue or Story
Iron Man storylines
Spider-Man storylines
Comics adapted into films |
1439_0 | Hemodynamics or haemodynamics are the dynamics of blood flow. The circulatory system is controlled by homeostatic mechanisms of autoregulation, just as hydraulic circuits are controlled by control systems. The hemodynamic response continuously monitors and adjusts to conditions in the body and its environment. Hemodynamics explains the physical laws that govern the flow of blood in the blood vessels.
Blood flow ensures the transportation of nutrients, hormones, metabolic waste products, oxygen, and carbon dioxide throughout the body to maintain cell-level metabolism, the regulation of the pH, osmotic pressure and temperature of the whole body, and the protection from microbial and mechanical harm.
Blood is a non-Newtonian fluid, and is most efficiently studied using rheology rather than hydrodynamics. Because blood vessels are not rigid tubes, classic hydrodynamics and fluids mechanics based on the use of classical viscometers are not capable of explaining haemodynamics. |
1439_1 | The study of the blood flow is called hemodynamics, and the study of the properties of the blood flow is called hemorheology.
Blood
Blood is a complex liquid. Blood is composed of plasma and formed elements. The plasma contains 91.5% water, 7% proteins and 1.5% other solutes. The formed elements are platelets, white blood cells, and red blood cells. The presence of these formed elements and their interaction with plasma molecules are the main reasons why blood differs so much from ideal Newtonian fluids.
Viscosity of plasma
Normal blood plasma behaves like a Newtonian fluid at physiological rates of shear. Typical values for the viscosity of normal human plasma at 37 °C is 1.4 mN·s/m2. The viscosity of normal plasma varies with temperature in the same way as does that of its solvent water; a 5 °C increase of temperature in the physiological range reduces plasma viscosity by about 10%. |
1439_2 | Osmotic pressure of plasma
The osmotic pressure of solution is determined by the number of particles present and by the temperature. For example, a 1 molar solution of a substance contains molecules per liter of that substance and at 0 °C it has an osmotic pressure of . The osmotic pressure of the plasma affects the mechanics of the circulation in several ways. An alteration of the osmotic pressure difference across the membrane of a blood cell causes a shift of water and a change of cell volume. The changes in shape and flexibility affect the mechanical properties of whole blood. A change in plasma osmotic pressure alters the hematocrit, that is, the volume concentration of red cells in the whole blood by redistributing water between the intravascular and extravascular spaces. This in turn affects the mechanics of the whole blood. |
1439_3 | Red blood cells
The red blood cell is highly flexible and biconcave in shape. Its membrane has a Young's modulus in the region of 106 Pa. Deformation in red blood cells is induced by shear stress. When a suspension is sheared, the red blood cells deform and spin because of the velocity gradient, with the rate of deformation and spin depending on the shear rate and the concentration.
This can influence the mechanics of the circulation and may complicate the measurement of blood viscosity. It is true that in a steady state flow of a viscous fluid through a rigid spherical body immersed in the fluid, where we assume the inertia is negligible in such a flow, it is believed that the downward gravitational force of the particle is balanced by the viscous drag force. From this force balance the speed of fall can be shown to be given by Stokes' law |
1439_4 | Where a is the particle radius, ρp, ρf are the respectively particle and fluid density μ is the fluid viscosity, g is the gravitational acceleration. From the above equation we can see that the sedimentation velocity of the particle depends on the square of the radius. If the particle is released from rest in the fluid, its sedimentation velocity Us increases until it attains the steady value called the terminal velocity (U), as shown above.
Hemodilution
Hemodilution is the dilution of the concentration of red blood cells and plasma constituents by partially substituting the blood with colloids or crystalloids. It is a strategy to avoid exposure of patients to the potential hazards of homologous blood transfusions. |
1439_5 | Hemodilution can be normovolemic, which implies the dilution of normal blood constituents by the use of expanders. During acute normovolemic hemodilution (ANH), blood subsequently lost during surgery contains proportionally fewer red blood cells per milliliter, thus minimizing intraoperative loss of the whole blood. Therefore, blood lost by the patient during surgery is not actually lost by the patient, for this volume is purified and redirected into the patient.
On the other hand, hypervolemic hemodilution (HVH) uses acute preoperative volume expansion without any blood removal. In choosing a fluid, however, it must be assured that when mixed, the remaining blood behaves in the microcirculation as in the original blood fluid, retaining all its properties of viscosity.
In presenting what volume of ANH should be applied one study suggests a mathematical model of ANH which calculates the maximum possible RCM savings using ANH, given the patients weight Hi and Hm. |
1439_6 | To maintain the normovolemia, the withdrawal of autologous blood must be simultaneously replaced by a suitable hemodilute. Ideally, this is achieved by isovolemia exchange transfusion of a plasma substitute with a colloid osmotic pressure (OP). A colloid is a fluid containing particles that are large enough to exert an oncotic pressure across the micro-vascular membrane.
When debating the use of colloid or crystalloid, it is imperative to think about all the components of the starling equation:
To identify the minimum safe hematocrit desirable for a given patient the following equation is useful: |
1439_7 | where EBV is the estimated blood volume; 70 mL/kg was used in this model and Hi (initial hematocrit) is the patient's initial hematocrit.
From the equation above it is clear that the volume of blood removed during the ANH to the Hm is the same as the BLs.
How much blood is to be removed is usually based on the weight, not the volume. The number of units that need to be removed to hemodilute to the maximum safe hematocrit (ANH) can be found by
This is based on the assumption that each unit removed by hemodilution has a volume of 450 mL (the actual volume of a unit will vary somewhat since completion of collection ais dependent on weight and not volume).
The model assumes that the hemodilute value is equal to the Hm prior to surgery, therefore, the re-transfusion of blood obtained by hemodilution must begin when SBL begins.
The RCM available for retransfusion after ANH (RCMm) can be calculated from the patient's Hi and the final hematocrit after hemodilution(Hm) |
1439_8 | The maximum SBL that is possible when ANH is used without falling below Hm(BLH) is found by assuming that all the blood removed during ANH is returned to the patient at a rate sufficient to maintain the hematocrit at the minimum safe level
If ANH is used as long as SBL does not exceed BLH there will not be any need for blood transfusion. We can conclude from the foregoing that H should therefore not exceed s.
The difference between the BLH and the BLs therefore is the incremental surgical blood loss (BLi) possible when using ANH.
When expressed in terms of the RCM
Where RCMi is the red cell mass that would have to be administered using homologous blood to maintain the Hm if ANH is not used and blood loss equals BLH.
The model used assumes ANH used for a 70 kg patient with an estimated blood volume of 70 ml/kg (4900 ml). A range of Hi and Hm was evaluated to understand conditions where hemodilution is necessary to benefit the patient. |
1439_9 | Result
The result of the model calculations are presented in a table given in the appendix for a range of Hi from 0.30 to 0.50 with ANH performed to minimum hematocrits from 0.30 to 0.15. Given a Hi of 0.40, if the Hm is assumed to be 0.25.then from the equation above the RCM count is still high and ANH is not necessary, if BLs does not exceed 2303 ml, since the hemotocrit will not fall below Hm, although five units of blood must be removed during hemodilution. Under these conditions, to achieve the maximum benefit from the technique if ANH is used, no homologous blood will be required to maintain the Hm if blood loss does not exceed 2940 ml. In such a case, ANH can save a maximum of 1.1 packed red blood cell unit equivalent, and homologous blood transfusion is necessary to maintain Hm, even if ANH is used.
This model can be used to identify when ANH may be used for a given patient and the degree of ANH necessary to maximize that benefit. |
1439_10 | For example, if Hi is 0.30 or less it is not possible to save a red cell mass equivalent to two units of homologous PRBC even if the patient is hemodiluted to an Hm of 0.15. That is because from the RCM equation the patient RCM falls short from the equation giving above.
If Hi is 0.40 one must remove at least 7.5 units of blood during ANH, resulting in an Hm of 0.20 to save two units equivalence. Clearly, the greater the Hi and the greater the number of units removed during hemodilution, the more effective ANH is for preventing homologous blood transfusion. The model here is designed to allow doctors to determine where ANH may be beneficial for a patient based on their knowledge of the Hi, the potential for SBL, and an estimate of the Hm. Though the model used a 70 kg patient, the result can be applied to any patient. To apply these result to any body weight, any of the values BLs, BLH and ANHH or PRBC given in the table need to be multiplied by the factor we will call T |
1439_11 | Basically, the model considered above is designed to predict the maximum RCM that can save ANH.
In summary, the efficacy of ANH has been described mathematically by means of measurements of surgical blood loss and blood volume flow measurement. This form of analysis permits accurate estimation of the potential efficiency of the techniques and shows the application of measurement in the medical field.
Blood flow
Cardiac output
The heart is the driver of the circulatory system, pumping blood through rhythmic contraction and relaxation. The rate of blood flow out of the heart (often expressed in L/min) is known as the cardiac output (CO). |
1439_12 | Blood being pumped out of the heart first enters the aorta, the largest artery of the body. It then proceeds to divide into smaller and smaller arteries, then into arterioles, and eventually capillaries, where oxygen transfer occurs. The capillaries connect to venules, and the blood then travels back through the network of veins to the right heart. The micro-circulation — the arterioles, capillaries, and venules —constitutes most of the area of the vascular system and is the site of the transfer of O2, glucose, and enzyme substrates into the cells. The venous system returns the de-oxygenated blood to the right heart where it is pumped into the lungs to become oxygenated and CO2 and other gaseous wastes exchanged and expelled during breathing. Blood then returns to the left side of the heart where it begins the process again. |
1439_13 | In a normal circulatory system, the volume of blood returning to the heart each minute is approximately equal to the volume that is pumped out each minute (the cardiac output). Because of this, the velocity of blood flow across each level of the circulatory system is primarily determined by the total cross-sectional area of that level. This is mathematically expressed by the following equation:
v = Q/A
where
v = velocity (cm/s)
Q = blood flow (ml/s)
A = cross sectional area (cm2)
Anatomical features
Circulatory system of species subjected to orthostatic blood pressure (such as arboreal snakes) has evolved with physiological and morphological features to overcome the circulatory disturbance. For instance, in arboreal snakes the heart is closer to the head, in comparison with aquatic snakes. This facilitates blood perfusion to the brain. |
1439_14 | Turbulence
Blood flow is also affected by the smoothness of the vessels, resulting in either turbulent (chaotic) or laminar (smooth) flow. Smoothness is reduced by the buildup of fatty deposits on the arterial walls.
The Reynolds number (denoted NR or Re) is a relationship that helps determine the behavior of a fluid in a tube, in this case blood in the vessel.
The equation for this dimensionless relationship is written as:
ρ: density of the blood
v: mean velocity of the blood
L: characteristic dimension of the vessel, in this case diameter
μ: viscosity of blood |
1439_15 | The Reynolds number is directly proportional to the velocity and diameter of the tube. Note that NR is directly proportional to the mean velocity as well as the diameter. A Reynolds number of less than 2300 is laminar fluid flow, which is characterized by constant flow motion, whereas a value of over 4000, is represented as turbulent flow. Due to its smaller radius and lowest velocity compared to other vessels, the Reynolds number at the capillaries is very low, resulting in laminar instead of turbulent flow. |
1439_16 | Velocity
Often expressed in cm/s. This value is inversely related to the total cross-sectional area of the blood vessel and also differs per cross-section, because in normal condition the blood flow has laminar characteristics. For this reason, the blood flow velocity is the fastest in the middle of the vessel and slowest at the vessel wall. In most cases, the mean velocity is used. There are many ways to measure blood flow velocity, like videocapillary microscoping with frame-to-frame analysis, or laser Doppler anemometry.
Blood velocities in arteries are higher during systole than during diastole. One parameter to quantify this difference is the pulsatility index (PI), which is equal to the difference between the peak systolic velocity and the minimum diastolic velocity divided by the mean velocity during the cardiac cycle. This value decreases with distance from the heart.
Blood vessels
Vascular resistance |
1439_17 | Resistance is also related to vessel radius, vessel length, and blood viscosity.
In a first approach based on fluids, as indicated by the Hagen–Poiseuille equation. The equation is as follows:
∆P: pressure drop/gradient
µ: viscosity
l: length of tube. In the case of vessels with infinitely long lengths, l is replaced with diameter of the vessel.
Q: flow rate of the blood in the vessel
r: radius of the vessel |
1439_18 | In a second approach, more realistic of the vascular resistance and coming from experimental observations on blood flows, according to Thurston, there is a plasma release-cell layering at the walls surrounding a plugged flow. It is a fluid layer in which at a distance δ, viscosity η is a function of δ written as η(δ), and these surrounding layers do not meet at the vessel centre in real blood flow. Instead, there is the plugged flow which is hyperviscous because holding high concentration of RBCs. Thurston assembled this layer to the flow resistance to describe blood flow by means of a viscosity η(δ) and thickness δ from the wall layer.
The blood resistance law appears as R adapted to blood flow profile :
where
R = resistance to blood flow
c = constant coefficient of flow
L = length of the vessel
η(δ) = viscosity of blood in the wall plasma release-cell layering
r = radius of the blood vessel
δ = distance in the plasma release-cell layer |
1439_19 | Blood resistance varies depending on blood viscosity and its plugged flow (or sheath flow since they are complementary across the vessel section) size as well, and on the size of the vessels.
Assuming steady, laminar flow in the vessel, the blood vessels behavior is similar to that of a pipe. For instance if p1 and p2 are pressures are at the ends of the tube, the pressure drop/gradient is:
The larger arteries, including all large enough to see without magnification, are conduits with low vascular resistance (assuming no advanced atherosclerotic changes) with high flow rates that generate only small drops in pressure. The smaller arteries and arterioles have higher resistance, and confer the main blood pressure drop across major arteries to capillaries in the circulatory system. |
1439_20 | In the arterioles blood pressure is lower than in the major arteries. This is due to bifurcations, which cause a drop in pressure. The more bifurcations, the higher the total cross-sectional area, therefore the pressure across the surface drops. This is why the arterioles have the highest pressure-drop. The pressure drop of the arterioles is the product of flow rate and resistance: ∆P=Q xresistance. The high resistance observed in the arterioles, which factor largely in the ∆P is a result of a smaller radius of about 30 µm. The smaller the radius of a tube, the larger the resistance to fluid flow. |
1439_21 | Immediately following the arterioles are the capillaries. Following the logic observed in the arterioles, we expect the blood pressure to be lower in the capillaries compared to the arterioles. Since pressure is a function of force per unit area, (P = F/A), the larger the surface area, the lesser the pressure when an external force acts on it. Though the radii of the capillaries are very small, the network of capillaries has the largest surface area in the vascular network. They are known to have the largest surface area (485 mm^2) in the human vascular network. The larger the total cross-sectional area, the lower the mean velocity as well as the pressure.
Substances called vasoconstrictors can reduce the size of blood vessels, thereby increasing blood pressure. Vasodilators (such as nitroglycerin) increase the size of blood vessels, thereby decreasing arterial pressure. |
1439_22 | If the blood viscosity increases (gets thicker), the result is an increase in arterial pressure. Certain medical conditions can change the viscosity of the blood. For instance, anemia (low red blood cell concentration) reduces viscosity, whereas increased red blood cell concentration increases viscosity. It had been thought that aspirin and related "blood thinner" drugs decreased the viscosity of blood, but instead studies found that they act by reducing the tendency of the blood to clot.
Wall tension
Regardless of site, blood pressure is related to the wall tension of the vessel according to the Young–Laplace equation (assuming that the thickness of the vessel wall is very small as compared to the diameter of the lumen): |
1439_23 | where
P is the blood pressure
t is the wall thickness
r is the inside radius of the cylinder.
is the cylinder stress or "hoop stress".
For the thin-walled assumption to be valid the vessel must have a wall thickness of no more than about one-tenth (often cited as one twentieth) of its radius.
The cylinder stress, in turn, is the average force exerted circumferentially (perpendicular both to the axis and to the radius of the object) in the cylinder wall, and can be described as:
where:
F is the force exerted circumferentially on an area of the cylinder wall that has the following two lengths as sides:
t is the radial thickness of the cylinder
l is the axial length of the cylinder |
1439_24 | Stress
When force is applied to a material it starts to deform or move. As the force needed to deform a material (e.g. to make a fluid flow) increases with the size of the surface of the material A., the magnitude of this force F is proportional to the area A of the portion of the surface. Therefore, the quantity (F/A) that is the force per unit area is called the stress. The shear stress at the wall that is associated with blood flow through an artery depends on the artery size and geometry and can range between 0.5 and 4 Pa.
.
Under normal conditions, to avoid atherogenesis, thrombosis, smooth muscle proliferation and endothelial apoptosis, shear stress maintains its magnitude and direction within an acceptable range. In some cases occurring due to blood hammer, shear stress reaches larger values. While the direction of the stress may also change by the reverse flow, depending on the hemodynamic conditions. Therefore, this situation can lead to atherosclerosis disease. |
1439_25 | Capacitance
Veins are described as the "capacitance vessels" of the body because over 70% of the blood volume resides in the venous system. Veins are more compliant than arteries and expand to accommodate changing volume.
Blood pressure
The blood pressure in the circulation is principally due to the pumping action of the heart. The pumping action of the heart generates pulsatile blood flow, which is conducted into the arteries, across the micro-circulation and eventually, back via the venous system to the heart. During each heartbeat, systemic arterial blood pressure varies between a maximum (systolic) and a minimum (diastolic) pressure. In physiology, these are often simplified into one value, the mean arterial pressure (MAP), which is calculated as follows:
MAP ≈ (BPdia) + (BPsys)
where:
MAP = Mean Arterial Pressure
BPdia = Diastolic blood pressure
BPsys = Systolic blood pressure |
1439_26 | Differences in mean blood pressure are responsible for blood flow from one location to another in the circulation. The rate of mean blood flow depends on both blood pressure and the resistance to flow presented by the blood vessels. Mean blood pressure decreases as the circulating blood moves away from the heart through arteries and capillaries due to viscous losses of energy. Mean blood pressure drops over the whole circulation, although most of the fall occurs along the small arteries and arterioles. Gravity affects blood pressure via hydrostatic forces (e.g., during standing), and valves in veins, breathing, and pumping from contraction of skeletal muscles also influence blood pressure in veins.
The relationship between pressure, flow, and resistance is expressed in the following equation:
Flow = Pressure/Resistance
When applied to the circulatory system, we get: |
1439_27 | CO = (MAP – RAP)/TPR
where
CO = cardiac output (in L/min)
MAP = mean arterial pressure (in mmHg), the average pressure of blood as it leaves the heart
RAP = right atrial pressure (in mmHg), the average pressure of blood as it returns to the heart
TPR = total peripheral resistance (in mmHg * min/L)
A simplified form of this equation assumes right atrial pressure is approximately 0:
CO ≈ MAP/TPR
The ideal blood pressure in the brachial artery, where standard blood pressure cuffs measure pressure, is <120/80 mmHg. Other major arteries have similar levels of blood pressure recordings indicating very low disparities among major arteries. In the innominate artery, the average reading is 110/70 mmHg, the right subclavian artery averages 120/80 and the abdominal aorta is 110/70 mmHg. The relatively uniform pressure in the arteries indicate that these blood vessels act as a pressure reservoir for fluids that are transported within them. |
1439_28 | Pressure drops gradually as blood flows from the major arteries, through the arterioles, the capillaries until blood is pushed up back into the heart via the venules, the veins through the vena cava with the help of the muscles. At any given pressure drop, the flow rate is determined by the resistance to the blood flow. In the arteries, with the absence of diseases, there is very little or no resistance to blood. The vessel diameter is the most principal determinant to control resistance. Compared to other smaller vessels in the body, the artery has a much bigger diameter (4 mm), therefore the resistance is low.
The arm–leg (blood pressure) gradient is the difference between the blood pressure measured in the arms and that measured in the legs. It is normally less than 10 mm Hg, but may be increased in e.g. coarctation of the aorta.
Clinical significance
Pressure monitoring |
1439_29 | Hemodynamic monitoring is the observation of hemodynamic parameters over time, such as blood pressure and heart rate. Blood pressure can be monitored either invasively through an inserted blood pressure transducer assembly (providing continuous monitoring), or noninvasively by repeatedly measuring the blood pressure with an inflatable blood pressure cuff.
Remote, indirect monitoring of blood flow by laser Doppler |
1439_30 | Noninvasive hemodynamic monitoring of eye fundus vessels can be performed by Laser Doppler holography, with near infrared light. The eye offers a unique opportunity for the non-invasive exploration of cardiovascular diseases. Laser Doppler imaging by digital holography can measure blood flow in the retina and choroid, whose Doppler responses exhibit a pulse-shaped profile with time This technique enables non invasive functional microangiography by high-contrast measurement of Doppler responses from endoluminal blood flow profiles in vessels in the posterior segment of the eye. Differences in blood pressure drive the flow of blood throughout the circulation. The rate of mean blood flow depends on both blood pressure and the hemodynamic resistance to flow presented by the blood vessels.
Glossary |
1439_31 | ANHAcute Normovolemic Hemodilution
ANHuNumber of Units During ANH
BLHMaximum Blood Loss Possible When ANH Is Used Before Homologous Blood Transfusion Is Needed
BLIIncremental Blood Loss Possible with ANH.(BLH – BLs)
BLsMaximum blood loss without ANH before homologous blood transfusion is required
EBVEstimated Blood Volume(70 mL/kg)
HctHaematocrit Always Expressed Here As A Fraction
HiInitial Haematocrit
HmMinimum Safe Haematocrit
PRBCPacked Red Blood Cell Equivalent Saved by ANH
RCMRed cell mass.
RCMHCell Mass Available For Transfusion after ANH
RCMIRed Cell Mass Saved by ANH
SBLSurgical Blood Loss
Etymology and pronunciation
The word hemodynamics () uses combining forms of hemo- (which comes from the ancient Greek haima, meaning blood) and dynamics, thus "the dynamics of blood". The vowel of the hemo- syllable is variously written according to the ae/e variation. |
1439_32 | Blood hammer
Blood pressure
Cardiac output
Cardiovascular System Dynamics Society
Electrical cardiometry
Esophogeal doppler
Hemodynamics of the aorta
Impedance cardiography
Photoplethysmogram
Laser Doppler imaging
Windkessel effect
Functional near-infrared spectroscopy
Notes and references |
1439_33 | Bibliography
Berne RM, Levy MN. Cardiovascular physiology. 7th Ed Mosby 1997
Rowell LB. Human Cardiovascular Control. Oxford University press 1993
Braunwald E (Editor). Heart Disease: A Textbook of Cardiovascular Medicine. 5th Ed. W.B.Saunders 1997
Siderman S, Beyar R, Kleber AG. Cardiac Electrophysiology, Circulation and Transport. Kluwer Academic Publishers 1991
American Heart Association
Otto CM, Stoddard M, Waggoner A, Zoghbi WA. Recommendations for Quantification of Doppler Echocardiography: A Report from the Doppler Quantification Task Force of the Nomenclature and Standards Committee of the American Society of Echocardiography. J Am Soc Echocardiogr 2002;15:167-184
Peterson LH, The Dynamics of Pulsatile Blood Flow, Circ. Res. 1954;2;127-139
Hemodynamic Monitoring, Bigatello LM, George E., Minerva Anestesiol, 2002 Apr;68(4):219-25
Claude Franceschi; Paolo Zamboni Principles of Venous Hemodynamics Nova Science Publishers 2009-01 ISBN Nr 1606924850/9781606924853 |
1439_34 | WR Milnor: Hemodynamics, Williams & Wilkins, 1982
B Bo Sramek: Systemic Hemodynamics and Hemodynamic Management, 4th Edition, ESBN 1-59196-046-0 |
1439_35 | External links
Learn hemodynamics
Fluid mechanics
Computational fluid dynamics
Cardiovascular physiology
Exercise physiology
Blood |
1440_0 | The Western Pennsylvania Professional Football Circuit was a loose association of American football clubs that operated from 1890 to approximately 1940. Originally amateur, professionalism was introduced to the circuit in 1892; cost pressures pushed the circuit to semi-professional status from about 1920 through the rest of its existence. Existing in some form for 48 years, it was one of the longest-lived paying football loops to operate outside the auspices of the National Football League. |
1440_1 | The football clubs of the 1880s and 1890s were amateur teams. They were under the membership of an athletic club, which provided both sports and the ability to wager money on the sports. However, the prestige and increased membership that could come from a successful team, led these clubs to begin secretly hiring talented players. The amateur athletics that these clubs engaged in were policed by the Amateur Athletic Union (AAU). By the mid-1890s allegations of professionalism became known to the AAU. The Allegheny Athletic Association was found guilty of paying cash to players and was permanently barred from any kind of competition with other AAU members. This punishment would end a team, because their opponents, whether other pros, amateur associations, or colleges, would have simply stopped playing them. Allegheny then defied the AAU in 1896 and created an entirely open professional team. A year later, the Latrobe Athletic Association, went entirely professional. The misconception |
1440_2 | that these were amateur athletic club were held to in public, even when newspapers wrote openly of players being under contract. To get around this, the circuit teams played for local or regional championships, with the only generally recognized national champion being the best college football team. However, the winner of the circuit was usually able to lay claim to a national, but professional, football title from 1890-1903. |
1440_3 | By 1904, the exodus of pro football talent to the "Ohio League", diminished the region's level of play and the national professional champions, were usually then claimed by the teams from Ohio. Though a champion was declared by the media, fans and clubs throughout this period, a formal league was not founded until 1920, when several teams from the "Ohio League" and the New York Pro Football League formed the American Professional Football Association. In 1922 the APFA became the National Football League. |
1440_4 | The circuit did not immediately die out and in fact experienced a slight renaissance in the 1920s as the Western Pennsylvania Senior Independent Football Conference. 1920s era blue laws in the state of Pennsylvania meant that while the NFL played its games on Sunday, Pennsylvania teams would have to play on Saturday; while this prevented the state's teams from joining the NFL until 1924, Pennsylvania teams could thus schedule exhibition games against NFL teams on either one's day off (other circuits such as the eastern Pennsylvania circuit and the Eastern/Anthracite Leagues also thrived in the 1920s) The J.P. Rooneys were founded in 1921; it later joined the NFL in 1933 as the Pittsburgh Pirates (now the Pittsburgh Steelers). Records of the Pirates playing other Western Pennsylvania teams (including the McKeesport Olympics) continue up to at least 1940, after which point most teams dissolved due to World War II; the Pirates (by now renamed the Steelers) then shifted its exhibition |
1440_5 | schedule to other minor league teams. |
1440_6 | Circuit "championships"
Other circuit teams
Erie Veterans
Glassport Odds
Jeannette Athletic Club
J.P. Rooneys (a.k.a. “Hope-Harveys” and “Majestic Radios”)
McKeesport Olympics
Oil City Athletic Club
Pitcairn Quakers
Pittsburgh Lyceum
Warslow Athletic Club
Historic professional football firsts
Several of the teams and individuals, in the circuit, pioneered several historic firsts for professional football. These accomplishments include: |
1440_7 | William "Pudge" Heffelfinger (Allegheny Athletic Association) became the first known professional football player on November 12, 1892.
Sport Donnelly (Allegheny Athletic Association) became the first known professional football coach in 1893.
A player assumed to be Grant Dibert (Pittsburgh Athletic Club) signed the first known pro football contract, which covered all of the club's games for the 1893 season.
John Brallier (Latrobe Athletic Association) became the first openly professional football player on September 3, 1895
Allegheny Athletic Association fielded the first entirely openly professional team in 1896.
Latrobe Athletic Association became the first football team to play a full season with only professionals in 1897.
William Chase Temple (Duquesne Country and Athletic Club) became the first individual owner of a professional football team in c.1898. |
1440_8 | The first ever professional football all-star game held between the Duquesne Country and Athletic Club and players from Western Pennsylvania All-Stars.
Adam Martin Wyant (Greensburg Athletic Club) was the first professional football player to get elected to the United States Congress in 1921. |
1440_9 | First known professional players
William "Pudge" Heffelfinger – Allegheny Athletic Association – $500 for one game on November 12, 1892.
Ben "Sport" Donnelly – Allegheny Athletic Association – $250 for one game on November 19, 1892.
Peter Wright – Allegheny Athletic Association – $50 per game (under contract) for the entire 1893 season.
James Van Cleve – Allegheny Athletic Association – $50 per game (under contract) for the entire 1893 season.
Ollie Rafferty – Allegheny Athletic Association – $50 per game (under contract) for the entire 1893 season.
Unknown player (assumed to be Grant Dibert) – Pittsburgh Athletic Club – for the entire 1893 season.
Lawson Fiscus – Greenburg Athletic Association – $20 per game (under contract) for the entire 1894 season.
John Brallier – Latrobe Athletic Association – $10 and expenses for one game on September 3, 1895.
Notes
References |
1440_10 | Warslow Athletic Club found on https://www.retroseasons.com/leagues/wppfc-western-pennsylvania-professional-football-circuit/1894/standings/ Retrieved 2020-4-7
See also
American football in Western Pennsylvania
History of American football
American football in Pennsylvania
Defunct American football leagues in the United States
Defunct professional sports leagues in the United States |
1441_0 | Rail transportation in the United States consists primarily of freight shipments, with a well integrated network of standard gauge private freight railroads extending into Canada and Mexico. Passenger service is mainly mass transit and commuter rail in major cities. Intercity passenger service, once a large and vital part of the nation's passenger transportation network, plays a limited role as compared to transportation patterns in many other countries. The United States has the largest rail transport network size of any country in the world. |
1441_1 | The nation's earliest railroads were built in the 1820s and 1830s, primarily in New England and the Mid-Atlantic region. The Baltimore and Ohio Railroad, chartered in 1827, was the nation's first common carrier railroad. By 1850, an extensive railroad network had begun to take shape in the rapidly industrializing Northeastern United States and the Midwest, while relatively fewer railroads were constructed in the primarily agricultural Southern United States. During and after the American Civil War, the first transcontinental railroad was built to connect California with the rest of the national network in Iowa. |
1441_2 | Railroads continued to expand throughout the rest of the 1800s, eventually reaching nearly every corner of the nation. The nation's railroads were temporarily nationalized between 1917 and 1920 by the United States Railroad Administration, as a result of U.S. entry into World War I. Railroad mileage in the nation peaked at this time. Railroads were affected deeply by the Great Depression in the United States, with some lines being abandoned during this time. A major increase in traffic during World War II brought a temporary reprieve, but after the war railroads faced intense competition from automobiles and aircraft and began a long decline. Passenger service was especially hard hit, with the federal government creating Amtrak in 1971 to take over responsibility for intercity passenger travel. Numerous railroad companies went bankrupt starting in the 1960s, most notably Penn Central Transportation Company in 1971, in the largest bankruptcy in the nation's history at the time. Once |
1441_3 | again, the federal government intervened, forming Conrail in 1976 to assume control of bankrupt railroads in the Northeast. |
1441_4 | Railroads' fortunes began to change following the passage of the Staggers Rail Act in 1980, which deregulated railroad companies, who had previously faced much stronger regulation than competing modes of transportation. With innovations such as trailer-on-flatcar and intermodal freight transport, railroad traffic began to increase. Following the Staggers Act, many railroads merged, forming major systems such as CSX and Norfolk Southern in the Eastern United States, and BNSF Railway in the Western United States, while Union Pacific Railroad purchased a number of competitors as well. Another result of the Staggers Act was the rise of shortline railroads, which formed to operate lines that major railroads abandoned or sold off. Hundreds of these companies were formed by the end of the century. Freight railroads invested in modernization and capacity improvements as they entered the 21st century, and intermodal transport continued to grow, while traditional traffic such as coal fell. |
1441_5 | History
To 1850
Between 1762 and 1764 a gravity railroad (mechanized tramway) (Montresor's Tramway) was built by British Army engineers up the steep riverside terrain near the Niagara River waterfall's escarpment at the Niagara Portage (which the local Senecas called "Crawl on All Fours.") in Lewiston, New York. |
1441_6 | In the 1820s–1840s, Americans closely watched the development of railways in Great Britain. The main competition came from canals, many of which were in operation under state ownership, and from privately owned steamboats plying the nation's vast river system. In 1829, Massachusetts prepared an elaborate plan. Government support, most especially the detailing of officers from the U.S. Army Corps of Engineers – the nation's only repository of civil engineering expertise – was crucial in assisting private enterprise in building nearly all the country's railroads. Army Engineer officers surveyed and selected routes, planned, designed, and constructed rights-of-way, track, and structures, and introduced the Army's system of reports and accountability to the railroad companies. More than one in ten of the 1,058 graduates from the U.S. Military Academy at West Point between 1802 and 1866 became corporate presidents, chief engineers, treasurers, superintendents and general managers of |
1441_7 | railroad companies. Among the Army officers who thus assisted the building and managing of the first American railroads were Stephen Harriman Long, George Washington Whistler, and Herman Haupt. |
1441_8 | State governments granted charters that created the business corporation and gave a limited right of eminent domain, allowing the railroad to buy needed land, even if the owner objected. |
1441_9 | The Baltimore and Ohio Railroad (B&O) was chartered in 1827 to build a steam railroad west from Baltimore, Maryland, to a point on the Ohio River. It began scheduled freight service over its first section on May 24, 1830. The first railroad to carry passengers, and, by accident, the first tourist railroad, began operating 1827. It was the Lehigh Coal & Navigation Company, initially a gravity road feeding anthracite coal downhill to the Lehigh Canal and using mule-power to return nine miles up the mountain; but, by the summer of 1829, as documented by newspapers, it regularly carried passengers. Later renamed the Summit Hill & Mauch Chunk Railroad, it added a steam powered cable-return track for true two-way operation by 1843, and ran as a common carrier and tourist road from the 1890s to 1937. Lasting 111 years, the SH&MC is described by some to be the world's first roller coaster. |
1441_10 | The first purpose-built common carrier railroad in the northeast was the Mohawk & Hudson Railroad; incorporated in 1826, it began operating in August 1831. Soon, a second passenger line, the Saratoga & Schenectady Railroad, started service in June 1832.
In 1835 the B&O completed a branch from Baltimore southward to Washington, D.C. The Boston & Providence Railroad was incorporated in 1831 to build a railroad between Boston, Massachusetts and Providence, Rhode Island; the road was completed in 1835 with the completion of the Canton Viaduct in Canton, Massachusetts. |
1441_11 | Numerous short lines were built, especially in the south, to provide connections to the river systems and the river boats common to the era. In Louisiana, the Pontchartrain Rail-Road, a route connecting the Mississippi River with Lake Pontchartrain at New Orleans was completed in 1831 and provided over a century of operation. Completed in 1830, the Tuscumbia, Courtland & Decatur Railroad became the first railroad constructed west of the Appalachian Mountains; it connected the two Alabama cities of Decatur and Tuscumbia.
Soon, other roads that would themselves be purchased or merged into larger entities, formed. The Camden & Amboy Railroad (C&A), the first railroad built in New Jersey, completed its route between its namesake cities in 1834. The C&A ran successfully for decades connecting New York City to the Delaware valley, and would eventually become part of the Pennsylvania Railroad. |
1441_12 | 1851–1900
By 1850, over of railroad lines had been built. The B&O's westward route reached the Ohio River in 1852, the first eastern seaboard railroad to do so. Railroad companies in the North and Midwest constructed networks that linked nearly every major city by 1860.
Transcontinental railroad |
1441_13 | The First Transcontinental Railroad in the U.S. was built across North America in the 1860s, linking the railroad network of the eastern U.S. with California on the Pacific coast. Finished on May 10, 1869, at the Golden spike event at Promontory Summit, Utah, it created a nationwide mechanized transportation network that revolutionized the population and economy of the American West, catalyzing the transition from the wagon trains of previous decades to a modern transportation system. It achieved the status of first transcontinental railroad by connecting myriad eastern U.S. railroads to the Pacific Ocean. However it was not the world's longest railroad, as Canada's Grand Trunk Railway (GTR) had, by 1867, already accumulated more than of track by connecting Portland, Maine, and the three northern New England states with the Canadian Atlantic provinces, and west as far as Port Huron, Michigan, through Sarnia, Ontario. |
1441_14 | Authorized by the Pacific Railway Act of 1862 and heavily backed by the federal government, the first transcontinental railroad was the culmination of a decades-long movement to build such a line and was one of the crowning achievements of the presidency of Abraham Lincoln, completed four years after his death. The building of the railroad required enormous feats of engineering and labor in the crossing of the Great Plains and the Rocky Mountains by the Union Pacific Railroad (UP) and Central Pacific Railroad, the two federally chartered enterprises that built the line westward and eastward respectively. The building of the railroad was motivated in part to bind the Union together during the strife of the American Civil War. It substantially accelerated the populating of the West by homesteaders, leading to rapid cultivation of new farm lands. The Central Pacific and the Southern Pacific Railroad combined operations in 1870 and formally merged in 1885; the Union Pacific originally |
1441_15 | bought the Southern Pacific in 1901 and was forced to divest it in 1913, but took it over again in 1996. |
1441_16 | Much of the original roadbed is still in use today and owned by UP, which is descended from both of the original railroads.
Rail gauge selection
Many Canadian and U.S. railroads originally used various broad gauges, but most were converted to by 1886, when the conversion of much of the southern rail network from gauge took place. This and the standardization of couplings and air brakes enabled the pooling and interchange of locomotives and rolling stock.
Impact of railroads on the economy
The railroad had its largest impact on the American transportation system during the second half of the 19th century. The standard historical interpretation holds that the railroads were central to the development of a national market in the United States and served as a model of how to organize, finance and manage a large corporation, along with allowing growth of the American population outside of the eastern regions. |
1441_17 | Take-off Thesis |
1441_18 | In 1944, American economic historian Leland Jenks (having conducted an analysis based on Joseph Schumpeter's theory of innovation) similarly claims that railroads had a direct impact on the growth of the United States' real income and an indirect impact on its economic expansion. In his Rostovian Take-off Thesis, Walt W. Rostow systematically developed the Jenks model that railroads were crucial to American economic growth. According to Rostow, railroads were responsible for the "take-off" of American industrialization in the period of 1843–1860. This "take-off" in economic growth occurred because the railroad helped to decrease transportation costs, transport new products and goods to commercial markets, and generally widen the market. Furthermore, the development of railroads stimulated the growth of the modern coal, iron, and engineering industries, all of which were essential for wider economic growth. According to Rostow's Take-off Thesis, railroads generated new investment, |
1441_19 | which simultaneously helped develop financial markets in the United States. |
1441_20 | Contemporary American economic historians have challenged this conventional view. The respective findings of Robert Fogel and Albert Fishlow do not support Rostow's claim that railroads stimulated widespread industrialization by increasing demand for coal, iron, and machinery. Drawing upon historical data, Robert Fogel found that the impact of railroads on the iron and steel industries was minimal: from 1840 to 1860, railroad production used less than five percent of the total pig iron produced. In addition, Fogel argues, only six percent of total coal production from 1840 to 1860 was consumed by railroads through consumption of iron products. Like Fogel, Fishlow showed that most railroads used very little coal during this time period because they were able to burn wood instead. Fishlow also found that iron used by railroads was only 20% of net consumption in the 1850s. |
1441_21 | Fogel and "essential" issue
Fogel concludes that railroads were important but not "essential" to late 19th-century growth in the U.S. in the sense that a possible alternative existed even if it was never tried. Fogel focuses on the "social saving" created by railroads, which he defines as the difference between the actual level of national income in 1890 and the theoretical level of national income if transportation somehow existed in the most efficient way possible to the absence of the railroad. He found that without the railroad, America's gross national product (GNP) would have been 7.2% less in 1890. While the largest contribution to GNP growth was made by any single innovation before 1900, this percentage only represents 2–3 years of GNP growth. |
1441_22 | Fogel makes several key assumptions and decisions in his analysis. First, his calculations comprise transportation between the primary markets of the Midwest and the secondary markets of the East and South (interregional) and transportation between cities and rural areas (intraregional). Second, he chooses to focus on the shipment of four agricultural commodities: wheat, corn, beef, and pork. Third, Fogel's social saving calculation accounts for costs not included in water rates (which include the cargo losses in transit, transshipment costs, extra wagon haulage, time lost because of slower speed, and because canals froze in the winter, and capital costs). One criticism of Fogel's analysis is that it does not account for the externalities or "spill-over" effects of the railroads, which (if included) may have increased his estimate for social savings [definition needed]. Railroads provided much of the demand for technological advances in a number of areas, including heat dynamics, |
1441_23 | combustion engineering, thermodynamics, metallurgy, civil engineering, machining, and metal fabrication. Furthermore, Fogel does not discuss the role railroads played in the development of the financial system or in attracting foreign capital, which otherwise might not have been available. |
1441_24 | Albert Fishlow
Fishlow estimates that the railroad's social savings—or what he terms "direct benefits"—were higher than those calculated by Fogel. Fishlow's research may indicate that the development of railroads significantly influenced real income in the United States. Instead of Fogel's term "social saving", Fishlow uses the term "direct benefits" to describe the difference between the actual level of national income in 1859 and the theoretical level of income using the least expensive, but existing alternative means. Fishlow calculated the social savings in 1859 at 4 percent of GNP and in 1890 at 15 percent of GNP—higher than Fogel's estimate of 7.2% in 1890. |
1441_25 | Monopolies, antitrust law, and regulation
Industrialists such as Cornelius Vanderbilt and Jay Gould became wealthy through railroad ownerships, as large railroad companies such as the New York Central, Grand Trunk Railway and the Southern Pacific spanned several states. In response to monopolistic practices (such as price fixing) and other excesses of some railroads and their owners, Congress created the Interstate Commerce Commission (ICC) in 1887. The ICC indirectly controlled the business activities of the railroads through issuance of extensive regulations. Congress also enacted antitrust legislation to prevent railroad monopolies, beginning with the Sherman Antitrust Act in 1890.
1901–1970 |
1441_26 | The principal mainline railroads concentrated their efforts on moving freight and passengers over long distances. But many had suburban services near large cities, which might also be served by Streetcar and Interurban lines. The Interurban was a concept which relied almost exclusively on passenger traffic for revenue. Unable to survive the Great Depression, the failure of most Interurbans by that time left many cities without suburban passenger railroads, although the largest cities such as New York City, Chicago, Boston and Philadelphia continued to have suburban service. The major railroads passenger flagship services included multi-day journeys on luxury trains resembling hotels, which were unable to compete with airlines in the 1950s. Rural communities were served by slow trains no more than twice a day. They survived until the 1960s because the same train hauled the Railway Post Office cars, paid for by the US Post Office. RPOs were withdrawn when mail sorting was mechanized. |
1441_27 | As early as the 1930s, automobile travel had begun to cut into the rail passenger market, somewhat reducing economies of scale, but it was the development of the Interstate Highway System and of commercial aviation in the 1950s and 1960s, as well as increasingly restrictive regulation, that dealt the most damaging blows to rail transportation, both passenger and freight. General Motors and others were convicted of running the streetcar industry into the ground purposefully in what is referred to as the Great American Streetcar Scandal. There was little point in operating passenger trains to advertise freight service when those who made decisions about freight shipping traveled by car and by air, and when the railroads' chief competitors for that market were interstate trucking companies. |
1441_28 | Soon, the only things keeping most passenger trains running were legal obligations. Meanwhile, companies who were interested in using railroads for profitable freight traffic were looking for ways to get out of those legal obligations, and it looked like intercity passenger rail service would soon become extinct in the United States beyond a few highly populated corridors. The final blow for passenger trains in the U.S. came with the loss of railroad post offices in the 1960s. On May 1, 1971, the federally funded Amtrak took over (with a few exceptions) all intercity passenger rail service in the continental United States. The Rio Grande, with its Denver-Ogden Rio Grande Zephyr and the Southern with its Washington, D.C.–New Orleans Southern Crescent chose to stay out of Amtrak, and the Rock Island, with two intrastate Illinois trains, was too far gone to be included into Amtrak. |
1441_29 | Freight transportation continued to labor under regulations developed when rail transport had a monopoly on intercity traffic, and railroads only competed with one another. An entire generation of rail managers had been trained to operate under this regulatory regime. Labor unions and their work rules were likewise a formidable barrier to change. Overregulation, management and unions formed an "iron triangle" of stagnation, frustrating the efforts of leaders such as the New York Central's Alfred E. Perlman. In particular, the dense rail network in the Northeastern U.S. was in need of radical pruning and consolidation. A spectacularly unsuccessful beginning was the 1968 formation and subsequent bankruptcy of the Penn Central, barely two years later.
1970–present |
1441_30 | Historically, on routes where a single railroad has had an undisputed monopoly, passenger service was as spartan and as expensive as the market and ICC regulation would bear, since such railroads had no need to advertise their freight services. However, on routes where two or three railroads were in direct competition with each other for freight business, such railroads would spare no expense to make their passenger trains as fast, luxurious, and affordable as possible, as it was considered to be the most effective way of advertising their profitable freight services. |
1441_31 | The National Association of Railroad Passengers (NARP) was formed in 1967 to lobby for the continuation of passenger trains. Its lobbying efforts were hampered somewhat by Democratic opposition to any sort of rail subsidies to the privately owned railroads, and Republican opposition to nationalization of the railroad industry. The proponents were aided by the fact that few in the federal government wanted to be held responsible for the seemingly inevitable extinction of the passenger train, which most regarded as tantamount to political suicide. The urgent need to solve the passenger train disaster was heightened by the bankruptcy filing of the Penn Central, the dominant railroad in the Northeast U.S., on June 21, 1970. |
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