4.1: Prelude to Molecular Orbital Theory
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Valence bond (VB) theory gave us a qualitative picture of chemical bonding, which was useful for predicting the shapes of molecules, bond strengths, etc. It fails to describe some bonding situations accurately because it ignores the wave nature of the electrons. Molecular orbital (MO) theory has the potential to be more quantitative. With it we can also get a picture of where the electrons are in the molecule, as shown in the image at the right. This can help us understand patterns of bonding and reactivity that are otherwise difficult to explain.
Although MO theory in principle gives us a way to calculate the energies and wavefunctions of electrons in molecules very precisely, usually we settle for simplified models here too. These simple models do not give very accurate orbital and bond energies, but they do explain concepts such as resonance (e.g., in the ferrocene molecule) that are hard to represent otherwise. We can get more accurate energies from MO theory by computational "number crunching." While MO theory is more correct than VB theory and can be very accurate in predicting the properties of molecules, it is also rather complicated even for fairly simple molecules. For example, you should have no trouble drawing the VB pictures for CO, NH 3 , and benzene, but we will find that these are increasingly challenging with MO theory.


7.3: Reading- Common Markets
A common market is the first stage towards a single market and may be limited initially to a free trade area.
KEY Points
- A common market is the first stage towards a single market and may be limited initially to a free trade area, with relatively free movement of capital and ofservices. However, it is not to a stage where the remaining trade barriers have been eliminated.
- The European Economic Community (EEC) (also known as the Common Market in the English-speaking world and sometimes referred to as the European Community even before it was renamed as such in 1993) was an international organization created by the 1957 Treaty of Rome.
- The main aim of the EEC, as stated in its preamble, was to “preserve peace and liberty and to lay the foundations of an ever closer union among the peoples of Europe.”
Term
- Free trade : International trade free from government interference, especially trade free from tariffs or duties on imports.
Example
- The European Economic Community was the first example of a both common and single market, but it was an economic union since it had additionally a customs union. The European Economic Community (EEC) was an international organization created by the 1957 Treaty of Rome. Its aim was to bring about economic integration, including a common market, among its six founding members: Belgium, France, Germany, Italy, Luxembourg and the Netherlands. Upon the entry into force of the Maastricht Treaty in 1993, the EEC was renamed the European Community (EC) to reflect that it covered a wider range of policy. This was also when the three European Communities, including the EC, were collectively made to constitute the first of the three pillars of the European Union (EU). For the customs union, the treaty provided for a 10% reduction in custom duties and up to 20% of global import quotas. Progress on the customs union proceeded much faster than the twelve years planned.
A common market is a first stage towards a single market and may be limited initially to a free trade area with relatively free movement of capital and of services, but not so advanced in reduction of the rest of the trade barriers.
The European Economic Community (EEC) (also known as the Common Market in the English-speaking world and sometimes referred to as the European Community even before it was renamed as such in 1993) was an international organization created by the 1957 Treaty of Rome. Its aim was to bring about economic integration, including a common market, among its six founding members: Belgium, France, Germany, Italy, Luxembourg, and the Netherlands.
It gained a common set of institutions along with the European Coal and Steel Community (ECSC) and the European Atomic Energy Community (EURATOM) as one of the European Communities under the 1965 Merger Treaty (Treaty of Brussels).
Upon the entry into force of the Maastricht Treaty in 1993, the EEC was renamed the European Community (EC) to reflect that it covered a wider range of policy. This was also when the three European Communities, including the EC, were collectively made to constitute the first of the three pillars of the European Union (EU), which the treaty also founded. The EC existed in this form until it was abolished by the 2009 Treaty of Lisbon, which merged the EU’s former pillars and provided that the EU would “replace and succeed the European Community. ” The main aim of the EEC, as stated in its preamble, was to “preserve peace and liberty and to lay the foundations of an ever closer union among the peoples of Europe. ” Calling for balanced economic growth, this was to be accomplished through:
- The establishment of a customs union with a common external tariff
- Common policies for agriculture, transport, and trade
- Enlargement of the EEC to the rest of Europe
For the customs union, the treaty provided for a 10% reduction in custom duties and up to 20% of global import quotas. Progress on the customs union proceeded much faster than the 12 years planned. However, France faced some setbacks due to its war with Algeria.
The six states that founded the EEC and the other two communities were known as the “inner six” (the “outer seven” were those countries who formed the European Free Trade Association). The six were France, West Germany, Italy, and the three Benelux countries: Belgium, the Netherlands, and Luxembourg. The first enlargement was in 1973, with the accession of Denmark, Ireland, and the United Kingdom. Greece, Spain, and Portugal joined in the 1980s. Following the creation of the EU in 1993, it has enlarged to include an additional 15 countries by 2007.
There were three political institutions that held the executive and legislative power of the EEC, plus one judicial institution and a fifth body created in 1975. These institutions (except for the auditors) were created in 1957 by the EEC but from 1967 on, they applied to all three communities. The council represents governments, the Parliament represents citizens, and the commission represents the European interest.
GLOSSARY
European Union
A supranational organization created in the 1950s to bring the nations of Europe into closer economic and political connection. At the beginning of 2007, 27 member nations were Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, The Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, United Kingdom. A supranational organization created in the 1950s to bring the nations of Europe into closer economic and political connection. At the beginning of 2012, 27 member nations were Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, The Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, United Kingdom.
Import
Something brought in from an exterior source, especially for sale or trade. To bring (something) in from a foreign country, especially for sale or trade.
Services
That which is produced, then traded, bought or sold, then finally consumed and consists of an action or work.
- International Business. Authored by : Boundless. Provided by : Boundless. Located at : https://www.boundless.com/business/ . License : CC BY-SA: Attribution-ShareAlike


6.14E: Desiccation
Desiccation is the state of extreme dryness, or the process of extreme drying and can be used to control microbial growth.
LEARNING OBJECTIVES
Show how desiccation inhibits microbes
Key Takeaways
Desiccation is the state of extreme dryness, or the process of extreme drying. In biology and ecology, desiccation refers to the drying out of a living organism. Microorganisms cannot grow and divide when desiccated, but can survive for certain periods of time, depending on their features. After the addition of water, the bacteria will start growing again, so desiccation does not provide complete sterilization.
Some bacteria, such as Deinococcus radiodurans and Mycobacterium , are extremely resistant to damage from prolonged desiccation while others, such as Neisseria gonorrhoeae, can survive only short periods of desiccation.
Pharmaceutical companies often use freeze-drying as a desiccation tool to increase the shelf life of products, such as vaccines and other injectables. By removing the water from the material and sealing the material in a vial, the material can be easily stored, shipped, and later reconstituted to its original form. Preservation is possible because the greatly reduced water content inhibits the action of microorganisms and enzymes that would normally spoil or degrade the substance. Another example from the pharmaceutical industry is the use of freeze-drying to produce tablets or wafers.
Drying is also a method for food preservation that works by removing water from the food, which inhibits the growth of microorganisms. Open air drying using sun and wind has been practiced since ancient times to preserve food. A solar or electric food dehydrator can greatly speed the drying process and ensure more consistent results. Water is usually removed by evaporation (air drying, sun drying, smoking, or wind drying) but, in the case of freeze-drying, food is first frozen and then the water is removed by sublimation. Bacteria, yeasts, and molds need the water in the food to grow, and drying effectively prevents them from surviving in food.
Freeze-drying is performed using special equipment. Two components are common to all types of freeze-dryers: a vacuum pump to reduce the ambient gas pressure in a vessel containing the substance to be dried, and a condenser to remove the moisture by condensation on a surface cooled to −40º to −80ºC.
Key Points
- Microorganisms cannot grow and divide when desiccated, but can survive for certain periods of time, depending on their features. After the addition of water, the bacteria will start growing again, so desiccation does not provide complete sterilization.
- Pharmaceutical companies often use freeze-drying as a desiccation tool to increase the shelf life of products, such as vaccines and other injectables. Drying is also a method for food preservation.
- Freeze-drying is performed using special equipment.
Key Terms
- desiccation : the state of drying
- freeze-drying : Freeze-drying, also known as lyophilisation, lyophilization, or cryodesiccation, is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport.


5.7: Network Representations
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- Ly-Huong T. Pham, Tejal Desai-Naik, Laurie Hammond, & Wael Abdeljabbar
- ASCCC Open Educational Resources Initiative (OERI)
To draw a diagram of a network, symbols are utilized by network professionals to represent the different devices and connections which make up a network.
A diagram gives a simple method to see how devices in a huge network are associated. This kind of "picture" of a network is known as a topology diagram. The capacity to perceive the legitimate portrayals of the physical systems administration segments is basic to have the option to imagine the association and activity of a network.
Notwithstanding these portrayals, particular phrasing is utilized while discussing how every one of these devices and media interfaces with one another. Significant terms to recall are:
- Network Interface Card : A NIC or LAN connector gives the physical association with the PC or opposite end device's network. The media that are associating the PC to the network administration device plug legitimately into the NIC.
- Physical Port : A connector or outlet on a network administration device where the media is associated with an end device or another network administration device.
- Interface : Specialized ports on a network administration device that associate with singular networks. Since switches are utilized to interconnect networks, the ports on a network allude to network interfaces.
Topology Diagrams
Understanding topology diagrams are required for anybody working with a network. They give a visual guide of how the network is associated.
There are two sorts of Topology diagrams:
- Physical topology and Logical topology diagrams. The physical topology diagrams identify the physical location of intermediary devices and cable installation.
- The Logical topology diagrams identify devices, addressing schemes, and ports.
With physical topology, it is quite self-explanatory. It is how they are interconnected with cables and wires physically. The logical topology is how connected devices are seen to the user.
Types of Networks
Networks foundations can fluctuate extraordinarily regarding:
- Size of the territory secured
- Number of users connected
- Number and kinds of administrations accessible
- Territory of obligation
The two most normal sorts of system frameworks:
- Local Area Network (LAN) : A network framework that gives access to clients and end devices in a little topographical zone, commonly an enterprise, small business, home, or small business network possessed and oversaw by an individual or IT department.
- Wide Area Network (WAN) : A network foundation that gives access to different networks over a wide topographical region, commonly possessed and overseen by a broadcast communications specialist co-op.
Different kinds of networks include:
- Metropolitan Area Network (MAN) : A network foundation that traverses a physical region bigger than a LAN yet littler than a WAN (e.g., a city). Keep an eye on are ordinarily worked by a solitary substance, for example, a huge association.
- Wireless LAN (WLAN) : Like a LAN , it remotely interconnects clients and focuses on a little geological region.
- Storage Area Network (SAN) : A network foundation intended to help record servers and give information stockpiling, recovery, and replication.
 Explicit highlights of LANs include:
- LANs interconnect end devices in a restricted region, for example, a home, school, place of business, or grounds.
- A solitary association or person normally directs a LAN. The managerial control that oversees the security and access control arrangements is upheld on the network level.
- LANs give rapid data transfer capacity to inward end gadgets and delegate devices.
 WANs are ordinarily overseen by specialist organizations (SP) or Internet Service Providers (ISP).
Explicit highlights of WANs include:
- WANs interconnect LANs over wide geological zones, for example, between urban areas, states, territories, nations, or the mainland.
- Numerous specialist organizations typically manage WANs.
- WANs ordinarily give more slow speed joins between LANs


3.5: Federal Regulation v. State Regulation- McDonald v. Chicago 561 U.S. 742 (2010)
OCTOBER TERM, 2009
MCDONALD V. CHICAGO
SUPREME COURT OF THE UNITED STATES
McDONALD et al. v . CITY OF CHICAGO, ILLINOIS, et al.
certiorari to the united states court of appeals for the seventh circuit
No. 08–1521. Argued March 2, 2010—Decided June 28, 2010
Two years ago, in District of Columbia v. Heller , 554 U. S. ___, this Court held that the Second Amendment protects the right to keep and bear arms for the purpose of self-defense and struck down a District of Columbia law that banned the possession of handguns in the home. Chicago (hereinafter City) and the village of Oak Park, a Chicago suburb, have laws effectively banning handgun possession by almost all private citizens. After Heller , petitioners filed this federal suit against the City, which was consolidated with two related actions, alleging that the City’s handgun ban has left them vulnerable to criminals. They sought a declaration that the ban and several related City ordinances violate the Second and Fourteenth Amendments. Rejecting petitioners’ argument that the ordinances are unconstitutional, the court noted that the Seventh Circuit previously had upheld the constitutionality of a handgun ban, that Heller had explicitly refrained from opining on whether the Second Amendment applied to the States, and that the court had a duty to follow established Circuit precedent. The Seventh Circuit affirmed, relying on three 19th-century cases— United States v. Cruikshank , 92 U. S. 542 , Presser v. Illinois , 116 U. S. 252 , and Miller v. Texas , 153 U. S. 535 —which were decided in the wake of this Court’s interpretation of the Fourteenth Amendment’s Privileges or Immunities Clause in the Slaughter-House Cases, 16 Wall. 36.
Held: The judgment is reversed, and the case is remanded.
567 F. 3d 856, reversed and remanded.
Justice Alito delivered the opinion of the Court with respect to Parts I, II–A, II–B, II–D, III–A, and III–B, concluding that the Fourteenth Amendment incorporates the Second Amendment right, recognized in Heller, to keep and bear arms for the purpose of self-defense. Pp. 5–9, 11–19, 19–33.
(a) Petitioners base their case on two submissions. Primarily, they argue that the right to keep and bear arms is protected by the Privileges or Immunities Clause of the Fourteenth Amendment and that the Slaughter-House Cases’ narrow interpretation of the Clause should now be rejected. As a secondary argument, they contend that the Fourteenth Amendment’s Due Process Clause incorporates the Second Amendment right. Chicago and Oak Park (municipal respondents) maintain that a right set out in the Bill of Rights applies to the States only when it is an indispensable attribute of any “ ‘civilized’ ” legal system. If it is possible to imagine a civilized country that does not recognize the right, municipal respondents assert, that right is not protected by due process. And since there are civilized countries that ban or strictly regulate the private possession of handguns, they maintain that due process does not preclude such measures. Pp. 4–5.
(b) The Bill of Rights, including the Second Amendment, originally applied only to the Federal Government, not to the States, see, e.g., Barron ex rel. Tiernan v. Mayor of Baltimore , 7 Pet. 243, 247, but the constitutional Amendments adopted in the Civil War’s aftermath fundamentally altered the federal system. Four years after the adoption of the Fourteenth Amendment, this Court held in the Slaughter-House Cases , that the Privileges or Immunities Clause protects only those rights “which owe their existence to the Federal government, its National character, its Constitution, or its laws,” 16 Wall., at 79, and that the fundamental rights predating the creation of the Federal Government were not protected by the Clause, id. , at 76. Under this narrow reading, the Court held that the Privileges or Immunities Clause protects only very limited rights. Id., at 79–80. Subsequently, the Court held that the Second Amendment applies only to the Federal Government in Cruikshank, 92 U. S. 542 , Presser, 116 U. S. 252 , and Miller, 153 U. S. 535 , the decisions on which the Seventh Circuit relied in this case. Pp. 5–9.
(c) Whether the Second Amendment right to keep and bear arms applies to the States is considered in light of the Court’s precedents applying the Bill of Rights’ protections to the States. Pp. 11–19.
(1) In the late 19th century, the Court began to hold that the Due Process Clause prohibits the States from infringing Bill of Rights protections. See, e.g., Hurtado v. California , 110 U. S. 516 . Five features of the approach taken during the ensuing era are noted. First, the Court viewed the due process question as entirely separate from the question whether a right was a privilege or immunity of national citizenship. See Twining v. New Jersey , 211 U. S. 78 , 99. Second, the Court explained that the only rights due process protected against state infringement were those “of such a nature that they are included in the conception of due process of law.” Ibid . Third, some cases during this era “can be seen as having asked … if a civilized system could be imagined that would not accord the particular protection” asserted therein. Duncan v. Louisiana , 391 U. S. 145 , 149, n. 14. Fourth, the Court did not hesitate to hold that a Bill of Rights guarantee failed to meet the test for Due Process Clause protection, finding, e.g., that freedom of speech and press qualified, Gitlow v. New York , 268 U. S. 652 , 666; Near v. Minnesota ex rel. Olson , 283 U. S. 697 , but the grand jury indictment requirement did not, Hurtado, supra. Finally, even when such a right was held to fall within the conception of due process, the protection or remedies afforded against state infringement sometimes differed from those provided against abridgment by the Federal Government. Pp. 11–13.
(2) Justice Black championed the alternative theory that §1 of the Fourteenth Amendment totally incorporated all of the Bill of Rights’ provisions, see, e.g. , Adamson v. California , 332 U. S. 46 , 71–72 (Black, J., dissenting), but the Court never has embraced that theory. Pp. 13–15.
(3) The Court eventually moved in the direction advocated by Justice Black, by adopting a theory of selective incorporation by which the Due Process Clause incorporates particular rights contained in the first eight Amendments. See, e.g. , Gideon v. Wainright , 372 U. S. 335 , 341. These decisions abandoned three of the characteristics of the earlier period. The Court clarified that the governing standard is whether a particular Bill of Rights protection is fundamental to our Nation’s particular scheme of ordered liberty and system of justice. Duncan, supra , at 149, n. 14. The Court eventually held that almost all of the Bill of Rights’ guarantees met the requirements for protection under the Due Process Clause. The Court also held that Bill of Rights protections must “all … be enforced against the States under the Fourteenth Amendment according to the same standards that protect those personal rights against federal encroachment.” Malloy v. Hogan , 378 U. S. 1 , 10. Under this approach, the Court overruled earlier decisions holding that particular Bill of Rights guarantees or remedies did not apply to the States. See, e.g. , Gideon, supra, which overruled Betts v. Brady , 316 U. S. 455 . Pp. 15–19.
(d) The Fourteenth Amendment makes the Second Amendment right to keep and bear arms fully applicable to the States. Pp. 19–33.
(1) The Court must decide whether that right is fundamental to the Nation’s scheme of ordered liberty, Duncan v. Louisiana , 391 U. S. 145 , 149, or, as the Court has said in a related context, whether it is “deeply rooted in this Nation’s history and tradition,” Washington v. Glucksberg, 521 U. S. 702 , 721. Heller points unmistakably to the answer. Self-defense is a basic right, recognized by many legal systems from ancient times to the present, and the Heller Court held that individual self-defense is “the central component” of the Second Amendment right. 554 U. S., at ___, ___. Explaining that “the need for defense of self, family, and property is most acute” in the home, ibid ., the Court found that this right applies to handguns because they are “the most preferred firearm in the nation to ‘keep’ and use for protection of one’s home and family,” id ., at ___, ___–___. It thus concluded that citizens must be permitted “to use [handguns] for the core lawful purpose of self-defense.” Id ., at ___. Heller also clarifies that this right is “deeply rooted in this Nation’s history and traditions, ” Glucksberg, supra, at 721. Heller explored the right’s origins in English law and noted the esteem with which the right was regarded during the colonial era and at the time of the ratification of the Bill of Rights. This is powerful evidence that the right was regarded as fundamental in the sense relevant here. That understanding persisted in the years immediately following the Bill of Rights’ ratification and is confirmed by the state constitutions of that era, which protected the right to keep and bear arms. Pp. 19–22.
(2) A survey of the contemporaneous history also demonstrates clearly that the Fourteenth Amendment’s Framers and ratifiers counted the right to keep and bear arms among those fundamental rights necessary to the Nation’s system of ordered liberty. Pp. 22–33.
(i) By the 1850’s, the fear that the National Government would disarm the universal militia had largely faded, but the right to keep and bear arms was highly valued for self-defense. Abolitionist authors wrote in support of the right, and attempts to disarm “Free-Soilers” in “Bloody Kansas,” met with outrage that the constitutional right to keep and bear arms had been taken from the people. After the Civil War, the Southern States engaged in systematic efforts to disarm and injure African Americans, see Heller , supra, at ___. These injustices prompted the 39th Congress to pass the Freedmen’s Bureau Act of 1866 and the Civil Rights Act of 1866 to protect the right to keep and bear arms. Congress, however, ultimately deemed these legislative remedies insufficient, and approved the Fourteenth Amendment. Today, it is generally accepted that that Amendment was understood to provide a constitutional basis for protecting the rights set out in the Civil Rights Act. See General Building Contractors Assn., Inc. v. Pennsylvania , 458 U. S. 375 , 389. In Congressional debates on the proposed Amendment, its legislative proponents in the 39th Congress referred to the right to keep and bear arms as a fundamental right deserving of protection. Evidence from the period immediately following the Amendment’s ratification confirms that that right was considered fundamental. Pp. 22–31.
(ii) Despite all this evidence, municipal respondents argue that Members of Congress overwhelmingly viewed §1 of the Fourteenth Amendment as purely an antidiscrimination rule. But while §1 does contain an antidiscrimination rule, i.e., the Equal Protection Clause, it can hardly be said that the section does no more than prohibit discrimination. If what municipal respondents mean is that the Second Amendment should be singled out for special—and specially unfavorable—treatment, the Court rejects the suggestion. The right to keep and bear arms must be regarded as a substantive guarantee, not a prohibition that could be ignored so long as the States legislated in an evenhanded manner. Pp. 30–33.
Justice Alito, joined by The Chief Justice, Justice Scalia, and Justice Kennedy, concluded, in Parts II–C, IV, and V, that the Fourteenth Amendment’s Due Process Clause incorporates the Second Amendment right recognized in Heller . Pp. 10–11, 33–44.
(a) Petitioners argue that that the Second Amendment right is one of the “privileges or immunities of citizens of the United States.” There is no need to reconsider the Court’s interpretation of the Privileges or Immunities Clause in the Slaughter-House Cases because, for many decades, the Court has analyzed the question whether particular rights are protected against state infringement under the Fourteenth Amendment’s Due Process Clause. Pp. 10–11.
(b) Municipal respondents’ remaining arguments are rejected because they are at war with Heller ’s central holding. In effect, they ask the Court to hold the right to keep and bear arms as subject to a different body of rules for incorporation than the other Bill of Rights guarantees. Pp. 33–40.
(c) The dissents’ objections are addressed and rejected. Pp. 41–44.
Justice Thomas agreed that the Fourteenth Amendment makes the Second Amendment right to keep and bear arms that was recognized in District of Columbia v. Heller , 554 U. S. ___, fully applicable to the States. However, he asserted, there is a path to this conclusion that is more straightforward and more faithful to the Second Amendment’s text and history. The Court is correct in describing the Second Amendment right as “fundamental” to the American scheme of ordered liberty, Duncan v. Louisiana , 391 U. S. 145 , 149, and “deeply rooted in this Nation’s history and traditions,” Washington v. Glucksberg , 521 U. S. 702 , 721. But the Fourteenth Amendment’s Due Process Clause, which speaks only to “process,” cannot impose the type of substantive restraint on state legislation that the Court asserts. Rather, the right to keep and bear arms is enforceable against the States because it is a privilege of American citizenship recognized by §1 of the Fourteenth Amendment, which provides, inter alia: “No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States.” In interpreting this language, it is important to recall that constitutional provisions are “ ‘written to be understood by the voters.’ ” Heller , 554 U. S., at ___. The objective of this inquiry is to discern what “ordinary citizens” at the time of the Fourteenth Amendment’s ratification would have understood that Amendment’s Privileges or Immunities Clause to mean. Ibid. A survey of contemporary legal authorities plainly shows that, at that time, the ratifying public understood the Clause to protect constitutionally enumerated rights, including the right to keep and bear arms. Pp. 1–34.
Alito, J., announced the judgment of the Court and delivered the opinion of the Court with respect to Parts I, II–A, II–B, II–D, III–A, and III–B, in which Roberts, C. J., and Scalia, Kennedy, and Thomas, JJ., joined, and an opinion with respect to Parts II–C, IV, and V, in which Roberts, C. J., and Scalia and Kennedy, JJ., join. Scalia, J., filed a concurring opinion. Thomas, J., filed an opinion concurring in part and concurring in the judgment. Stevens, J., filed a dissenting opinion. Breyer, J., filed a dissenting opinion, in which Ginsburg and Sotomayor, JJ., joined.
Contributors and Attributions
- Authored by : US Government . Located at : https://supreme.justia.com/cases/federal/us/561/742/ . License : Public Domain: No Known Copyright


2.5: LU Decomposition
View LU Decomposition on YouTube
The process of Gaussian elimination also results in the factoring of the matrix \(\text{A}\) to
\[\text{A}=\text{LU},\nonumber \]
where \(\text{L}\) is a lower triangular matrix and \(\text{U}\) is an upper triangular matrix. Using the same matrix \(\text{A}\) as in the last section, we show how this factorization is realized. We have
\[\left(\begin{array}{rrr}-3&2&-1\\6&-6&7\\3&-4&4\end{array}\right)\to\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\3&-4&4\end{array}\right)=\text{M}_1\text{A},\nonumber \]
where
\[\text{M}_1\text{A}=\left(\begin{array}{ccc}1&0&0\\2&1&0\\0&0&1\end{array}\right)\left(\begin{array}{rrr}-3&2&-1\\6&-6&7\\3&-4&4\end{array}\right)=\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\3&-4&4\end{array}\right).\nonumber \]
Note that the matrix \(\text{M}_1\) performs row elimination on the second row using the first row. Two times the first row is added to the second row.
The next step is
\[\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\3&-4&4\end{array}\right)\to\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\0&-2&3\end{array}\right)=\text{M}_2\text{M}_1\text{A},\nonumber \]
where
\[\text{M}_2\text{M}_1\text{A}=\left(\begin{array}{rrr}1&0&0\\0&1&0\\1&0&1\end{array}\right)\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\3&-4&4\end{array}\right)=\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\0&-2&3\end{array}\right).\nonumber \]
Note that the matrix \(\text{M}_2\) performs row elimination on the third row using the first row. One times the first row is added to the third row.
The last step is
\[\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\0&-2&3\end{array}\right)\to\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\0&0&-2\end{array}\right)=\text{M}_3\text{M}_2\text{M}_1\text{A},\nonumber \]
where
\[\text{M}_3\text{M}_2\text{M}_1\text{A}=\left(\begin{array}{rrr}1&0&0\\0&1&0\\0&-1&1\end{array}\right)\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\0&-2&3\end{array}\right)=\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\0&0&-2\end{array}\right).\nonumber \]
Here, \(\text{M}_3\) performs row elimination on the third row using the second row. Minus one times the second row is added to the third row. We now have
\[\text{M}_3\text{M}_2\text{M}_1\text{A}=\text{U}\nonumber \]
or
\[\text{A}=\text{M}_1^{-1}\text{M}_2^{-1}\text{M}_3^{-1}\text{U}.\nonumber \]
The inverse matrices are easy to find. The matrix \(\text{M}_1\) multiples the first row by \(2\) and adds it to the second row. To invert this operation, we simply need to multiply the first row by \(−2\) and add it to the second row, so that
\[\text{M}_1=\left(\begin{array}{ccc}1&0&0\\2&1&0\\0&0&1\end{array}\right),\quad\text{M}_1^{-1}=\left(\begin{array}{rrr}1&0&0\\-2&1&0\\0&0&1\end{array}\right).\nonumber \]
To check that
\[\text{M}_1\text{M}_1^{-1}=\text{I},\nonumber \]
we multiply
\[\left(\begin{array}{ccc}1&0&0\\2&1&0\\0&0&1\end{array}\right)\left(\begin{array}{rrr}1&0&0\\-2&1&0\\0&0&1\end{array}\right)=\left(\begin{array}{rrr}1&0&0\\0&1&0\\0&0&1\end{array}\right).\nonumber \]
Similarly,
\[\text{M}_2=\left(\begin{array}{rrr}1&0&0\\0&1&0\\1&0&1\end{array}\right),\quad\text{M}_2^{-1}=\left(\begin{array}{rrr}1&0&0\\0&1&0\\-1&0&1\end{array}\right),\nonumber \]
and
\[\text{M}_3=\left(\begin{array}{rrr}1&0&0\\0&1&0\\0&-1&1\end{array}\right),\quad\text{M}_3^{-1}=\left(\begin{array}{rrr}1&0&0\\0&1&0\\0&1&1\end{array}\right).\nonumber \]
Therefore,
\[\text{L}=\text{M}_1^{-1}\text{M}_2^{-1}\text{M}_3^{-1}\nonumber \]
is given by
\[\text{L}=\left(\begin{array}{rrr}1&0&0\\-2&1&0\\0&0&1\end{array}\right)\left(\begin{array}{rrr}1&0&0\\0&1&0\\-1&0&1\end{array}\right)\left(\begin{array}{rrr}1&0&0\\0&1&0\\0&1&1\end{array}\right)=\left(\begin{array}{rrr}1&0&0\\-1&2&0\\-1&1&1\end{array}\right),\nonumber \]
which is lower triangular. Notice that the off-diagonal elements of \(\text{M}_1^{−1}\), \(\text{M}_2^{−1}\), and \(\text{M}_3^{-1}\) are simply combined to form \(\text{L}\). Without actually multiplying matrices, one could obtain this result by considering how an elementary matrix performs row reduction on another elementary matrix. Our \(\text{LU}\) decomposition is therefore
\[\left(\begin{array}{rrr}-3&2&-1\\6&-6&7\\3&-4&4\end{array}\right)=\left(\begin{array}{rrr}1&0&0\\-2&1&0\\-1&1&1\end{array}\right)\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\0&0&-2\end{array}\right).\nonumber \]
Another nice feature of the \(\text{LU}\) decomposition is that it can be done by overwriting \(\text{A}\), therefore saving memory if the matrix \(\text{A}\) is very large.
The \(\text{LU}\) decomposition is useful when one needs to solve \(\text{Ax} = \text{b}\) for \(\text{x}\) when \(\text{A}\) is fixed and there are many different \(\text{b}\)’s. First one determines \(\text{L}\) and \(\text{U}\) using Gaussian elimination. Then one writes
\[(\text{LU})\text{x}=\text{L}(\text{Ux})=\text{b}.\nonumber \]
We let
\[\text{y}=\text{Ux},\nonumber \]
and first solve
\[\text{Ly}=\text{b}\nonumber \]
for \(\text{y}\) by forward substitution. We then solve
\[\text{Ux}=\text{y}\nonumber \]
for \(\text{x}\) by back substitution. If we count operations, we can show that solving \((\text{LU})\text{x} = \text{b}\) is a factor of \(n\) faster once \(\text{L}\) and \(\text{U}\) are in hand than solving \(\text{Ax} = \text{b}\) directly by Gaussian elimination.
We now illustrate the solution of \(\text{LUx} = \text{b}\) using our previous example, where
\[\text{L}=\left(\begin{array}{rrr}1&0&0\\-2&1&0\\-1&1&1\end{array}\right),\quad\text{U}=\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\0&0&-2\end{array}\right),\quad\text{b}=\left(\begin{array}{r}-1\\-7\\-6\end{array}\right).\nonumber \]
With \(\text{y} = \text{Ux}\), we first solve \(\text{Ly} = \text{b}\), that is
\[\left(\begin{array}{rrr}1&0&0\\-2&1&0\\-1&1&1\end{array}\right)\left(\begin{array}{c}y_1\\y_2\\y_3\end{array}\right)=\left(\begin{array}{c}-1\\-7\\-6\end{array}\right).\nonumber \]
Using forward substitution
\[\begin{aligned}y_1&=-1, \\ y_2&=-7+2y_1=-9, \\ y_3&=-6+y_1-y_2=2.\end{aligned} \nonumber \]
We now solve \(\text{Ux} = \text{y}\), that is
\[\left(\begin{array}{rrr}-3&2&-1\\0&-2&5\\0&0&-2\end{array}\right)\left(\begin{array}{c}x_1\\x_2\\x_3\end{array}\right)=\left(\begin{array}{r}-1\\-9\\2\end{array}\right).\nonumber \]
Using back substitution,
\[\begin{aligned}x_3&=-\frac{1}{2}(2)=-1, \\ x_2&=-\frac{1}{2}(-9-5x_3)=2, \\ x_1&=-\frac{1}{3}(-1-2x_2+x_3)=2,\end{aligned} \nonumber \]
and we have once again determined
\[\left(\begin{array}{c}x_1\\x_2\\x_3\end{array}\right)=\left(\begin{array}{r}2\\2\\-1\end{array}\right).\nonumber \]
When performing Gaussian elimination, recall that the diagonal element that one uses during the elimination procedure is called the pivot. To obtain the correct multiple, one uses the pivot as the divisor to the elements below the pivot. Gaussian elimination in this form will fail if the pivot is zero. In this case, a row interchange must be performed.
Even if the pivot is not identically zero, a small value can result in an unstable numerical computation. For large matrices solved by a computer, one can easily lose all accuracy in the solution. To avoid these round-off errors arising from small pivots, row interchanges are made, and the numerical technique is called partial pivoting. This method of \(\text{LU}\) decomposition with partial pivoting is the one usually taught in a standard numerical analysis course.


6.0: Prelude to Problem Solving and Need Recognition Techniques
Portions of the material in this section are based on original work by Geoffrey Graybeal and produced with support from the Rebus Community. The original is freely available under the terms of the CC BY 4.0 license at https://press.rebus.community/media-...repreneurship/ .
Marah Lidey and Naomi Hirabayashi met when they worked together at DoSomething.org, a youth-oriented global nonprofit organization. They considered each other aspirational peers—accessible friends they looked up to and leaned on. While working together, they got the idea to turn the support they gave each other into a product idea: an inspirational platform that would send users a motivational text message each day. In 2015, Hirabayashi and Lidey began to focus on turning their idea into a reality. They conducted a test with seventy individuals before publicly releasing Shine in beta in October 2015. They formally left DoSomething.Org in April 2016 and their startup venture, Shine, was born.
The problem Shine tackles is that “self-help is broken” and its value proposition addresses in part what is known as “the confidence gap,” often cited as a barrier that holds women back when it comes to advancing in their careers, raising money, investing, and planning retirement. Shine has four pillars it is built to address: mental health, confidence, daily happiness, and productivity. As of 2018, the Shine community had two million users from 189 countries. What began as a motivational text message service has since evolved to include an app and additional services such as Shine Talks and audio challenges.
Hirabayashi and Lidey recognized a need—or an entrepreneurial opportunity . You learned about identifying opportunities in the chapter on Identifying Entrepreneurial Opportunity . This chapter will explore what happens next—the problem solving and need recognition techniques that entrepreneurs employ to carry the idea forward, and to solve issues that arise as the enterprise advances. Problem solving is essential to the genesis of entrepreneurship. At the same time, problem-solving techniques can be used in management and in an individual’s everyday personal life.


3.1: Viruses
Viruses are acellular, parasitic entities that are not classified within any kingdom. Viruses are not cells and cannot divide. They infect a host cell and use the host’s replication processes to produce identical progeny virus particles. Viruses infect organisms as diverse as bacteria, plants, and animals and exist in a netherworld between a living organism and a nonliving entity. Living things grow, metabolize, and reproduce. Viruses replicate, but to do so, they are entirely dependent on their host cells.
-
- 3.1.1: Prelude to Viruses
- Viruses are acellular, parasitic entities that are not classified within any kingdom. Unlike most living organisms, viruses are not cells and cannot divide. Instead, they infect a host cell and use the host’s replication processes to produce identical progeny virus particles. Viruses infect organisms as diverse as bacteria, plants, and animals. They exist in a netherworld between a living organism and a nonliving entity.
-
- 3.1.2: Viral Evolution, Morphology, and Classification
- Viruses are diverse entities. They vary in their structure, their replication methods, and in their target hosts. Nearly all forms of life—from bacteria and archaea to eukaryotes such as plants, animals, and fungi—have viruses that infect them. While most biological diversity can be understood through evolutionary history, such as how species have adapted to conditions and environments, much about virus origins and evolution remains unknown.
-
- 3.1.3: Virus Infections and Hosts
- Viruses can be seen as obligate, intracellular parasites. A virus must attach to a living cell, be taken inside, manufacture its proteins and copy its genome, and find a way to escape the cell so that the virus can infect other cells. Viruses can infect only certain species of hosts and only certain cells within that host. Cells that a virus may use to replicate are called permissive.
-
- 3.1.4: Prevention and Treatment of Viral Infections
- Viruses cause a variety of diseases in animals, including humans, ranging from the common cold to potentially fatal illnesses like meningitis. These diseases can be treated by antiviral drugs or by vaccines, but some viruses, such as HIV, are capable of both avoiding the immune response and mutating to become resistant to antiviral drugs.
Thumbnail: Ebola virus. (Public Domain; CDC).


9.7.3: Counter Argument Paragraphs
Counter-Argument Paragraphs
The purpose of a counter argument is to consider (and show that you are considering) perspectives other than your own. A counter-argument tears down other viewpoints; it does not build up your own, which you should do in separate paragraphs.
Placement of Counter-Arguments in an Essay
A counter argument can appear anywhere in the essay, but it most commonly appears:
- As part of your introduction—before you propose your thesis—where the existence of a different view is the motive for your essay. This works if your entire essay will be a counter-argument and you are not building up your own argument.
- As a section or paragraph just after your introduction, in which you lay out the expected reaction or standard position of opposing viewpoints before turning away to develop your own.
- As a quick move within a paragraph, where you imagine a counter-argument not to your main idea but to the sub-idea that the paragraph is arguing or is about to argue.
- As a section or paragraph just before the conclusion of your essay, in which you imagine what someone might object to in what you have argued. (However, this is really too late to be very effective in persuading someone to your position. It only shows you are considering other points of view.
Watch that you don't overdo it. A turn into counter argument here and there will sharpen and energize your essay, but too many such turns will have the reverse effect by obscuring your main idea or suggesting that you're ambivalent about your point of view. At the worst, it can sound like you are contradicting yourself. Writing a lead-in sentence with subordination or concession can help avoid this problem.
Example Counter-Argument
The following paragraph explains an opposing point of view to the writer's position in almost the whole paragraph. Words in bold italics explain the essential component of a counter-argument that a writer is doing in the following sentence(s).
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Considering the many challenges facing K-12 public schools, it’s understandable that many people would be eager to pursue new options. Supporters of school choice point out that under the current public school system, parents with economic means already exercise school choice by moving from areas with failing or dangerous schools to neighborhoods with better, safer schools. Their argument is that school choice would allow all parents the freedom, regardless of income level, to select the school that provides the best education (Chub and Moe). Schools would then have to compete for students by offering higher academic results and greater safety. Schools unable to measure up to the standards of successful schools would fail and possibly close. [Acknowledge Valid Parts and move to your own viewpoint] Activists within the school choice movement can be applauded for seeking to improve public education, but the changes they propose would in fact seriously damage public education as a whole. |
The next paragraph is the counter-argument to the previous paragraph. Notice, however, that this count-argument does have some problems. The writer doesn't distinguish between public and private charter schools and also creates some logical fallacies in the process. Counter-arguments should be logically solid, cite sources, and argue logically.
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One of the biggest dangers of school choice is the power behind large corporations specializing in opening and operating charter schools. Two notable companies are Green Dot, which is the leading public school operator in Los Angeles (Green Dot), and KIPP, which operates 65 schools in 19 different states (KIPP). These companies represent a growing trend of privatization of public schools by large corporations. It is feared that these corporations could grow to a point that public control of education would be lost. Education policy would be left in the hands of entrepreneurial think tanks, corporate boards of directors, and lobbyists who are more interested in profit than educating students (Miller and Gerson). The results of this could be just as bad or worse than what is currently happening in underperforming schools. Education should be left in the hands of professional educators and not business people with MBAs. |
At this point, the writer would then begin to argue their point of view with sub-claims and facts developed in a number of paragraphs to support their thesis.
If a writer is constructing an entire essay as a counter-argument, then the writer will need to fully develop multiple, well-supported arguments against the other point of view. The writer may also want to point out any logical flaws or other errors in the argument that they oppose.
Contributors and Attributions
- Revision, Adaptation, and Original Content. Provided by: Libretexts. License: CC BY-SA 4.0: Attribution.
This page most recently updated on June 6, 2020.


41.3.8: Chapter 9
Review Questions
1.
b.
The central nervous system (CNS) is composed of the brain and the spinal cord. Therefore, the nurse would recognize that an ischemic stroke involves deficits originating in the CNS.
2.
d.
The cerebellum, located below the cerebrum, controls coordination of movement and postural adjustment.
3.
a.
The cervical vertebrae are located in the neck region of the body.
4.
d.
The autonomic nervous system regulates involuntary responses by regulating cardiac muscle and smooth muscle contraction in addition to gland activity.
5.
c.
The parasympathetic nervous system, or “rest and digest” system, is activated when the body is relaxed and not under actual or perceived stress.
6.
b.
The sympathetic nervous system, or “fight or flight system,” is activated when the body is under actual or perceived stress to ready the body’s response to a potential threat.
7.
b.
Neurotransmission is the nervous system’s communication process by which electrical signals are sent down the axon and transformed into chemical messengers.
8.
a.
The most common neurotransmitters of the autonomic nervous system are acetylcholine and norepinephrine.
9.
b.
Medications that stimulate the release of acetylcholine are known as parasympathomimetic due to their mimicking of the parasympathetic nervous system.
10.
d.
The beta1 adrenergic receptor would be indicated in this instance. Specifically, this medication would be a beta1 blocker.


1.7: Mary Shelley (1797-1851)
Mary Shelley was born to important writers and philosophers, Mary Wollstonecraft and William Godwin. Mary Wollstonecraft died soon after Mary was born. She grew up in her father’s care along with her halfsister, Fanny Imlay (1794-1816), and, after Godwin’s marriage to Mary Jane Clairmont (1766-1841), her stepsister Jane (known as Claire). Claire received a formal education; however, Mary educated herself, mainly through reading her father’s many books. She early showed literary aspirations, publishing a poem entitled “Mounseer Nongtongpaw” when she was only ten. She also showed a remarkable independence of spirit by eloping with Percy Bysshe Shelley in 1814. Although Percy Bysshe’s wife Harriet refused to join them in this elopement, Mary’s stepsister Claire did not refuse to do so.
They led an itinerant life throughout Europe, struggling both financially and emotionally as they lost their first child in 1815 and then their second in 1816. For a summer, they stayed in Switzerland along with Lord Byron and the physician John Polidori (1795-1821). Byron challenged each of them to write a frightening story, and Mary met that challenge with Frankenstein, or the Modern Prometheus. In the preface to the second edition of this novel, Mary wrote that she dreamt almost in its entirety the moment when the student of “unhallowed arts” brings to life the creature—assembled of body parts selected for their beauty—in a convulsive moment. She awoke from this dream, frightened, and decided that if it frightened her, then it would likely frighten her housemates.
Mary learned of two suicides while she worked on this novel. Her sister Fanny poisoned herself with an overdose of laudanum after suffering years of domestic tension with her father and stepmother. Harriet Shelley drowned herself, perhaps despondent over her out-of-wedlock pregnancy with an unknown man (supposed to be a military officer). A birth also occurred, that of Byron’s daughter Allegra with Claire Clairmont. Byron agreed to see to Allegra’s upbringing provided that he never have anything more to do with the child’s mother. Unsurprisingly, Mary’s novel explores not only bringing the dead to life (or “giving birth” without a mother) but also the family’s role in a child’s rearing, good and bad parenting, and the “making” of a monster through nurture—bad nurturing—rather than the “monstrosity” being attributable to nature.
Mary and Percy Bysshe married after Harriet’s death. They had four children, only one of whom, Percy Florence (1819-1889), survived to adulthood. As a family, the Shelleys were not entirely happy. Percy Bysshe remained unconstrained by conventions and had several affairs with various women, including Claire. After the early deaths of her daughter Clara (1818) and son William (1818), Mary became increasingly depressed and isolated, only recovering with the birth of Percy Florence.
Percy Bysshe drowned in 1822. As a single mother, Mary received some support from Percy Bysshe’s father, though he refused to meet Mary in person. Percy Florence inherited the family estate upon Sir Timothy’s death in 1844. Mary thereafter dedicated herself to building and protecting Percy Bysshe’s literary reputation. And she wrote several works, including travelogues, novels, and plays. Her writing advances and advocates for women’s roles not only in the family but also in society, challenging the patriarchy and misogyny current in her time.
1.14.1: From Frankenstein, or the Modern Prometheus
Did I request thee, Maker, from my clay
To mould Me man? Did I solicit thee
From darkness to promote me?—
Paradise Lost (X. 743-5)
Letter 1
To Mrs. Saville, England
St. Petersburgh, Dec. 11th, 17-
You will rejoice to hear that no disaster has accompanied the commencement of an enterprise which you have regarded with such evil forebodings. I arrived here yesterday, and my first task is to assure my dear sister of my welfare and increasing confidence in the success of my undertaking.
I am already far north of London, and as I walk in the streets of Petersburgh, I feel a cold northern breeze play upon my cheeks, which braces my nerves and fills me with delight. Do you understand this feeling? This breeze, which has travelled from the regions towards which I am advancing, gives me a foretaste of those icy climes. Inspirited by this wind of promise, my daydreams become more fervent and vivid. I try in vain to be persuaded that the pole is the seat of frost and desolation; it ever presents itself to my imagination as the region of beauty and delight. There, Margaret, the sun is forever visible, its broad disk just skirting the horizon and diffusing a perpetual splendour. There—for with your leave, my sister, I will put some trust in preceding navigators—there snow and frost are banished; and, sailing over a calm sea, we may be wafted to a land surpassing in wonders and in beauty every region hitherto discovered on the habitable globe. Its productions and features may be without example, as the phenomena of the heavenly bodies undoubtedly are in those undiscovered solitudes. What may not be expected in a country of eternal light? I may there discover the wondrous power which attracts the needle and may regulate a thousand celestial observations that require only this voyage to render their seeming eccentricities consistent forever. I shall satiate my ardent curiosity with the sight of a part of the world never before visited, and may tread a land never before imprinted by the foot of man.  But supposing all these conjectures to be false, you cannot contest the inestimable benefit which I shall confer on all mankind, to the last generation, by discovering a passage near the pole to those countries, to reach which at present so many months are requisite; or by ascertaining the secret of the magnet, which, if at all possible, can only be effected by an undertaking such as mine.
These reflections have dispelled the agitation with which I began my letter, and I feel my heart glow with an enthusiasm which elevates me to heaven, for nothing contributes so much to tranquillize the mind as a steady purpose—a point on which the soul may fix its intellectual eye. This expedition has been the favourite dream of my early years. I have read with ardour the accounts of the various voyages which have been made in the prospect of arriving at the North Pacific Ocean through the seas which surround the pole. You may remember that a history of all the voyages made for purposes of discovery composed the whole of our good Uncle Thomas’ library. My education was neglected, yet I was passionately fond of reading.
These visions faded when I perused, for the first time, those poets whose effusions entranced my soul and lifted it to heaven. I also became a poet and for one year lived in a paradise of my own creation; I imagined that I also might obtain a niche in the temple where the names of Homer and Shakespeare are consecrated.  But just at that time I inherited the fortune of my cousin, and my thoughts were turned into the channel of their earlier bent.
Six years have passed since I resolved on my present undertaking. I can, even now, remember the hour from which I dedicated myself to this great enterprise. I commenced by inuring my body to hardship. I accompanied the whale-fishers on several expeditions to the North Sea; I voluntarily endured cold, famine, thirst, and want of sleep; I often worked harder than the common sailors during the day and devoted my nights to the study of mathematics, the theory of medicine, and those branches of physical science from which a naval adventurer might derive the greatest practical advantage. Twice I actually hired myself as an under-mate in a Greenland whaler, and acquitted myself to admiration. I must own I felt a little proud when my captain offered me the second dignity in the vessel and entreated me to remain with the greatest earnestness, so valuable did he consider my services. And now, dear Margaret, do I not deserve to accomplish some great purpose? My life might have been passed in ease and luxury, but I preferred glory to every enticement that wealth placed in my path. Oh, that some encouraging voice would answer in the affirmative! My courage and my resolution is firm; but my hopes fluctuate, and my spirits are often depressed. I am about to proceed on a long and difficult voyage, the emergencies of which will demand all my fortitude: I am required not only to raise the spirits of others, but sometimes to sustain my own, when theirs are failing.
This is the most favourable period for travelling in Russia. They fly quickly over the snow in their sledges; the motion is pleasant, and, in my opinion, far more agreeable than that of an English stagecoach. The cold is not excessive, if you are wrapped in furs—a dress which I have already adopted, for there is a great difference between walking the deck and remaining seated motionless for hours, when no exercise prevents the blood from actually freezing in your veins. I have no ambition to lose my life on the post-road between St. Petersburgh and Archangel. I shall depart for the latter town in a fortnight or three weeks; and my intention is to hire a ship there, which can easily be done by paying the insurance for the owner, and to engage as many sailors as I think necessary among those who are accustomed to the whale-fishing. I do not intend to sail until the month of June; and when shall I return? Ah, dear sister, how can I answer this question?  If I fail, you will see me again soon, or never. Farewell, my dear, excellent Margaret. Heaven shower down blessings on you, and save me, that I may again and again testify my gratitude for all your love and kindness.
Your affectionate brother,
R. Walton
Letter 2
To Mrs. Saville, England
Archangel, 28th March, 17-
How slowly the time passes here, encompassed as I am by frost and snow! Yet a second step is taken towards my enterprise. I have hired a vessel and am occupied in collecting my sailors; those whom I have already engaged appear to be men on whom I can depend and are certainly possessed of dauntless courage.
But I have one want which I have never yet been able to satisfy, and the absence of the object of which I now feel as a most severe evil, I have no friend, Margaret: when I am glowing with the enthusiasm of success, there will be none to participate my joy; if I am assailed by disappointment, no one will endeavour to sustain me in dejection. I shall commit my thoughts to paper, it is true; but that is a poor medium for the communication of feeling. I desire the company of a man who could sympathize with me, whose eyes would reply to mine. You may deem me romantic, my dear sister, but I bitterly feel the want of a friend. I have no one near me, gentle yet courageous, possessed of a cultivated as well as of a capacious mind, whose tastes are like my own, to approve or amend my plans. How would such a friend repair the faults of your poor brother! I am too ardent in execution and too impatient of difficulties. But it is a still greater evil to me that I am self-educated: for the first fourteen years of my life I ran wild on a common and read nothing but our Uncle Thomas’ books of voyages. At that age I became acquainted with the celebrated poets of our own country; but it was only when it had ceased to be in my power to derive its most important benefits from such a conviction that I perceived the necessity of becoming acquainted with more languages than that of my native country. Now I am twenty-eight and am in reality more illiterate than many schoolboys of fifteen. It is true that I have thought more and that my daydreams are more extended and magnificent, but they want (as the painters call it) KEEPING; and I greatly need a friend who would have sense enough not to despise me as romantic, and affection enough for me to endeavour to regulate my mind. Well, these are useless complaints; I shall certainly find no friend on the wide ocean, nor even here in Archangel, among merchants and seamen. Yet some feelings, unallied to the dross of human nature, beat even in these rugged bosoms. My lieutenant, for instance, is a man of wonderful courage and enterprise; he is madly desirous of glory, or rather, to word my phrase more characteristically, of advancement in his profession. He is an Englishman, and in the midst of national and professional prejudices, unsoftened by cultivation, retains some of the noblest endowments of humanity. I first became acquainted with him on board a whale vessel; finding that he was unemployed in this city, I easily engaged him to assist in my enterprise. The master is a person of an excellent disposition and is remarkable in the ship for his gentleness and the mildness of his discipline. This circumstance, added to his well-known integrity and dauntless courage, made me very desirous to engage him. A youth passed in solitude, my best years spent under your gentle and feminine fosterage, has so refined the groundwork of my character that I cannot overcome an intense distaste to the usual brutality exercised on board ship: I have never believed it to be necessary, and when I heard of a mariner equally noted for his kindliness of heart and the respect and obedience paid to him by his crew, I felt myself peculiarly fortunate in being able to secure his services. I heard of him first in rather a romantic manner, from a lady who owes to him the happiness of her life. This, briefly, is his story. Some years ago he loved a young Russian lady of moderate fortune, and having amassed a considerable sum in prize-money, the father of the girl consented to the match. He saw his mistress once before the destined ceremony; but she was bathed in tears, and throwing herself at his feet, entreated him to spare her, confessing at the same time that she loved another, but that he was poor, and that her father would never consent to the union. My generous friend reassured the suppliant, and on being informed of the name of her lover, instantly abandoned his pursuit. He had already bought a farm with his money, on which he had designed to pass the remainder of his life; but he bestowed the whole on his rival, together with the remains of his prize-money to purchase stock, and then himself solicited the young woman’s father to consent to her marriage with her lover. But the old man decidedly refused, thinking himself bound in honour to my friend, who, when he found the father inexorable, quitted his country, nor returned until he heard that his former mistress was married according to her inclinations. “What a noble fellow!” you will exclaim. He is so; but then he is wholly uneducated: he is as silent as a Turk, and a kind of ignorant carelessness attends him, which, while it renders his conduct the more astonishing, detracts from the interest and sympathy which otherwise he would command.
Yet do not suppose, because I complain a little or because I can conceive a consolation for my toils which I may never know, that I am wavering in my resolutions. Those are as fixed as fate, and my voyage is only now delayed until the weather shall permit my embarkation. The winter has been dreadfully severe, but the spring promises well, and it is considered as a remarkably early season, so that perhaps I may sail sooner than I expected. I shall do nothing rashly: you know me sufficiently to confide in my prudence and considerateness whenever the safety of others is committed to my care.
I cannot describe to you my sensations on the near prospect of my undertaking. It is impossible to communicate to you a conception of the trembling sensation, half pleasurable and half fearful, with which I am preparing to depart. I am going to unexplored regions, to “the land of mist and snow,” but I shall kill no albatross; therefore do not be alarmed for my safety or if I should come back to you as worn and woeful as the “Ancient Mariner.” You will smile at my allusion, but I will disclose a secret. I have often attributed my attachment to, my passionate enthusiasm for, the dangerous mysteries of ocean to that production of the most imaginative of modern poets. There is something at work in my soul which I do not understand. I am practically industrious—painstaking, a workman to execute with perseverance and labour—but besides this there is a love for the marvellous, a belief in the marvellous, intertwined in all my projects, which hurries me out of the common pathways of men, even to the wild sea and unvisited regions I am about to explore. But to return to dearer considerations. Shall I meet you again, after having traversed immense seas, and returned by the most southern cape of Africa or America? I dare not expect such success, yet I cannot bear to look on the reverse of the picture. Continue for the present to write to me by every opportunity: I may receive your letters on some occasions when I need them most to support my spirits. I love you very tenderly. Remember me with affection, should you never hear from me again.
Your affectionate brother,
Robert Walton


5.21: Dielectric Breakdown
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The permittivity of an ideal dielectric is independent of the magnitude of an applied electric field; the material is said to be “linear.” 1 However, all practical dielectrics fail in this respect with sufficiently strong electric field. Typically, the failure is abrupt and is observed as a sudden, dramatic increase in conductivity, signaling that electrons are being successfully dislodged from their host molecules. The threshold value of the electric field intensity at which this occurs is known as the dielectric strength , and the sudden change in behavior observed in the presence of an electric field greater than this threshold value is known as dielectric breakdown .
Dielectric strength varies from about 3 MV/m for air to about 200 MV/m in mica (a dielectric commonly used in capacitors).
Dielectric breakdown is typically accompanied by “arcing,” which is a sudden flow of current associated with the breakdown. A well known example of this phenomenon is lightning, which occurs when charge is exchanged between sky and ground when air (a dielectric) exhibits breakdown. Dielectric breakdown in solids typically damages the material.


12.2: Star Life
There are specific terms in biology, which deal with life: birth, growing up, getting old, death, and even evolution. For the sake of convenience and familiarity, astronomers use similar terminology when dealing with stars. This module will focus on astronomical concepts, such as stars being born or stellar birth, stellar nurseries, stellar life, stars growing old, star death, and stellar evolution. Note that stars are not alive! These are simply terms of familiarity. Stars are formed in interstellar medium , which is filled with hydrogen, helium, and dust. This interstellar medium is cold and dense. These areas in space are also called Molecular Clouds, Interstellar Clouds, or Stellar Nurseries (more than one star).
One debate that transpired in the 1800s into the early 1900s was the question of what composed the stars. A doctoral student at Harvard, Cecelia Payne-Gaposhkin , noted in her 1925 doctoral dissertation that stars were made of hydrogen. Not all agreed with Payne-Gaposhkin’s findings, yet as more data was collected and researched, her theory was proven correct a few short years after she first proposed the theory.
So how are stars ‘born’? That is, what are the steps to a stellar birth? First, hydrogen, helium, and dust – the interstellar medium – has to accumulate. The interstellar medium starts to collapse due to gravity; these various atoms and dust particles attract each other, forming larger and larger clumps, attracting more gas and dust. As the interstellar medium collapses, the density, pressure, and temperature within the interstellar medium increases. Think of it like this: as the density increases, more particles are striking each other, generating more energy and heat.


12.2: Reading- Optimizing Channels
Introduction
Geico didn’t simply find itself owning the online, direct channel. It analyzed its customer needs and competitors’ positions and chose a strategy to accelerate sales growth: Geico defined and managed its channel strategy.
The Channel Management Process
The channel management process contains five steps.
1. Analyze the Consumer
We begin the process of channel management by answering two questions. First, to whom shall we sell this merchandise immediately? Second, who are our ultimate users and buyers? The immediate and ultimate customers may be identical or they may be quite separate. In both cases, certain basic questions apply: There is a need to know what the customer needs, where they buy, when they buy, why they buy from certain outlets, and how they buy.
It is best that we first identify the traits of the ultimate user, since the results of that evaluation might determine the other channel institutions we would use to meet those needs. For example, the buying characteristics of the purchaser of a high-quality curved TV might be the following:
- purchased only from a well-established, reputable dealer
- purchased only after considerable research to compare prices and merchandise characteristics
- purchase may be postponed
- purchased only from a dealer equipped to provide prompt and reasonable product service
These buying specifications illustrate the kinds of requirements that the manufacturer must discover. In most cases, purchase specifications are fairly obvious and can be determined without great difficulty. In others, though, they can be difficult to determine. For example, some consumers will only dine at restaurants that serve menu items that meet particular dietary needs; others will only patronize supermarkets that demonstrate social responsibility in their sourcing and packaging. Still, through careful and imaginative research, most of the critical factors related to consumer buying specifications can be figured out.
Once the consumer’s buying specifications are known, the channel planner can decide on the type or types of wholesaler or retailer through which a product should be sold. This means that a manufacturer contemplating distribution through particular types of retailers must become intimately familiar with the precise location and performance characteristics of those he is considering.
In much the same way that buying specifications of ultimate users are determined, the manufacturers must also discover buying specifications for resellers. Of particular importance is the question “From whom do my retail outlets prefer to buy?” The answer to this question determines the types of wholesalers (if any) that the manufacturer should use. Although many retailers prefer to buy directly from the manufacturers, this is not always the case. Often, the exchange requirements of manufacturers (e.g., infrequent visit, large order requirements, and stringent credit terms) are the opposite of those desired by retailers. Such retailers would rather buy from local distributors who have lenient credit terms and offer a wide assortment of merchandise.
2. Establish the Channel Objectives
Once customer needs are specified, the marketer can decide what the channel must achieve, which can be captured in the channel objectives. Channel objectives are based on customer requirements, the marketing strategy, and the company strategy and objectives. However, in cases where a company is just getting started, or an older company is trying to carve out a new market niche, the channel objectives may be the dominant objectives. For example, a small manufacturer wants to expand outside the local market. An immediate obstacle is the limited shelf space available to this manufacturer. The addition of a new product to the shelves generally means that space previously assigned to competitive products must be obtained. Without this exposure, the product is doomed.
As one would expect, there is wide diversity of channel objectives. The following areas encompass the major categories:
- Growth in sales by reaching new markets and/or increasing sales in existing markets.
- Maintenance or improvement of market share
- Achieve a pattern of distribution by a certain time, place, and form
- Reduce costs or increase profits by creating an efficient channel
3. Specify Distribution Tasks
After the distribution objectives are set, it is appropriate to determine the specific distribution tasks (functions) to be performed in that channel system. The channel manager must be very specific in describing the tasks and also detail how these tasks will change depending upon the situation. For example, a manufacturer might delineate the following tasks as necessary to profitably reach the target market:
- Provide delivery within 48 hours after order placement
- Offer adequate storage space
- Provide credit to other intermediaries
- Facilitate a product return network
- Provide readily available inventory (quantity and type)
4. Evaluate and Select Among Channel Alternatives
Determining the specific channel tasks is a prerequisite of the evaluation and selection process. There are four considerations for channel alternatives: number of levels, intensity at the various levels, types of intermediaries at each level, and application of selection criteria to channel alternatives. In addition, it is important to decide who will be in charge of the selected channels.
Number of Levels
Channels can range in levels from two to several (five is typical). The two-level channel (producer to consumer) is a direct channel. The number of levels in a particular industry might be the same for all the companies simply because of tradition. In other industries, this dimension is more flexible and subject to rapid change.
Intensity at Each Level
Once the number of levels has been decided, the channel manager needs to determine the actual number of channel components involved at each level. How many retailers in a particular market should be included in the distribution network? How many wholesalers?
The intensity decision is extremely critical, because it is an important part of the firm’s overall marketing strategy. Companies such as Starbucks and Hershey’s have achieved high levels of success through their intensive distribution strategy.
Types of Intermediaries and Application of Selection Criteria
As we discussed, there are several types of intermediaries that operate in a particular channel system. The objective is to identify several possible alternative channel structures, and evaluate these alternatives with respect to some set of criteria such as company factors, environmental trends, reputation of the reseller, and experience of the reseller.
Who Should Lead?
Regardless of the channel framework selected, channels usually perform better if someone is in charge, providing some level of leadership. Essentially, the purpose of this leadership is to coordinate the goals and efforts of channel institutions. The level of leadership can range from very passive to quite active—verging on dictatorial. The style may range from very negative, based on fear and punishment, to very positive, based on encouragement and reward. In a given situation, any of these leadership styles may prove effective.
Under which conditions should the manufacturers lead? The wholesaler? The retailer? While the answer is contingent upon many factors, in general, the manufacturer should lead if control of the product (merchandising, repair) is critical and if the design and redesign of the channel is best done by the manufacturer. The wholesaler should lead where the manufacturers and retailers have remained small in size, large in number, relatively scattered geographically, are financially weak, and lack marketing expertise. The retailer should lead when product development and demand stimulation are relatively unimportant and when personal attention to the customer is important.
5. Evaluating Channel Member Performance
The need to evaluate the performance level of the channel members is just as important as the evaluation of the other marketing functions. Clearly, the marketing mix is quite interdependent, and the failure of one component can cause the failure of the whole. There is one important difference, though: the channel member is dealing with independent business firms, rather than employees and activities under its control, these firms may be reluctant to change their practices.
Sales is the most popular performance criterion used in channel evaluation. Other possible performance criteria are maintenance of adequate inventory, selling capabilities, attitudes of channel intermediaries toward the product, competition from other intermediaries and from other product lines carried by the manufacturer’s own channel members.
Correcting or Modifying the Channel
As a result of the evaluation process, or because of other factors such as new competition, technology, or market potential, changes may need to be made in the channel structure. Because channel relationships tend to be long-term, and the channel decision has such a pervasive impact on the business, any change should be carefully evaluated. Later in this module we will discuss service outputs and their role in measuring and modifying channel performance.
The Human Aspect of Distribution
By its very nature, a channel of distribution is made up of people. Ideally, a channel member should coordinate his or her efforts with other members in such a way that the performance of the total distribution system to which he or she belongs is enhanced. This is rarely the case, though. Part of this lack of cooperation is due to the organizational structure of many channels, which encourages a channel member to be concerned only with channel members immediately adjacent to them, from whom they buy and to whom they sell. A second reason is the tendency of channel members to exhibit their independence as separate business operations. It is difficult to gain cooperation under this arrangement. Four human dimensions have been incorporated into the study of channel behavior: roles, communication, conflict, and power. It is assumed that an understanding of these behavioral characteristics will increase the effectiveness of the channel.
Role
Most channel members participate in several channels. Establishing the role of a channel member means defining what the behavior of the channel member should be. For example, a basic role prescription of the manufacturer may be to maximize the sales of his or her particular brand of product. This suggests that the manufacturer is to actively compete for market share and aggressively promote his or her brand. The role prescriptions of independent wholesalers, however, are likely to be quite different. Since wholesalers may represent several competing manufacturers, their role would be to build sales with whatever brands are most heavily demanded by retailers. Therefore, a major issue in channel management is defining the role prescriptions of the various participants in order to achieve desired results. This is accomplished through a careful appraisal of the tasks to be performed by each channel member and clear communication of these roles to the members.
Communication
Channel communication is sending and receiving information that is relevant to the operation of the channel. It is critical for the the channel member to foster an effective flow of information within the channel. Communication will take place only if the channel member is aware of the pitfalls that await. The channel manager should therefore try to detect any behavioral problems that inhibit the effective flow of information through the channel and try to solve these problems before the communication process in the channel becomes seriously distorted.
Conflict
Any time individuals or organizations must work together and rely on one another for personal success, conflict is inevitable. In a distribution channel, conflict usually arises in one of two forms: structural or behavioral.
Structural conflict occurs when the channel partners are expected to cooperate and compete. For example, imagine that you want to buy a new pair of Nike shoes and you have two choices. You can go to a local Foot Locker retailer and buy the shoes for $89, or you can go online to Nike.com and buy the shoes for $69. In effect, Nike is undercutting its retail channel while selling through a direct channel. It is likely that Foot Locker is unhappy about this. While a retailer expects to compete with other retailers who carry the same brands, it doesn’t expect that the manufacturer will sell through the direct channel at deep discounts. This type of structural conflict is often the cause of behavioral conflict.
All organizations expect to manage some level of behavioral conflict in the channel. They do this by:
- Establishing a mechanism for detecting conflict
- Evaluating the effects of the conflict
- Resolving the conflict
Given the distributed nature of the channel, it is often difficult to resolve conflict. Strategies such as the formation of a channel committee, joint goal setting, and bringing in arbitrators have all been used. In some cases, conflict becomes part of the ongoing channel dynamic—it’s difficult but manageable. Eric Schmidt, chairman and CEO of Google Inc., notes: “From my experience the most successful companies are the ones where there is enormous conflict. Conflict does not mean killing one another, but instead means there is a process by which there is a disagreement. It is okay to have different points of view and disagree, because tolerance of multiple opinions and people often leads to the right decision through some kind of process.”
Power
Power is the capacity to use force in a relationship. It is often the means by which one party is able to control or influence the behavior of another party. In the channel mechanism, power refers to the capacity of a particular channel member to control or influence the behavior of another channel member. For instance, a large retailer may want the manufacturer to modify the design of the product or perhaps be required to carry less inventory. Both parties may attempt to exert their power in an attempt to influence the other’s behavior. The ability of either of the parties to achieve this outcome will depend on the amount of power that each can bring to bear.
Contributors and Attributions
- Adaptation and Revision. Provided by : Lumen Learning. License : CC BY: Attribution
- Chapter 10, Channel Concepts: Distributing the Product, from Introducing Marketing. Authored by : John Burnett. Provided by : Global Text. License : CC BY: Attribution
- Madagascar day gecko. Authored by : kuhnmi. Located at : https://www.flickr.com/photos/31176607@N05/16537089484/ . License : CC BY: Attribution
- Camp Vienna. Authored by : Nico Grienauer. Located at : https://www.flickr.com/photos/nico_g/7542560062/ . License : CC BY: Attribution


11.3: Pressure
Learning Objectives
By the end of this section, you will be able to:
- Define pressure.
- Explain the relationship between pressure and force.
- Calculate force given pressure and area.
You have no doubt heard the word pressure being used in relation to blood (high or low blood pressure) and in relation to the weather (high- and low-pressure weather systems). These are only two of many examples of pressures in fluids.
Definition: Pressure
Pressure is defined as the force divided by the area perpendicular to the force over which the force is applied, or
\[P = \dfrac{F}{A}. \label{pressure}\]
where \(F\) is a force applied to an area \(A\) that is perpendicular to the force.
A given force can have a significantly different effect depending on the area over which the force is exerted, as shown in Figure Figure \(\PageIndex{1}\). The SI unit for pressure is the pascal , where
\[1 \, Pa = 1 \, N/m^2.\]
In addition to the pascal, there are many other units for pressure that are in common use. In meteorology, atmospheric pressure is often described in units of millibar (mb), where
\[100 \, mb = 1 \times 10^4 \, Pa.\]
Pounds per square inch \((lb/in^2 \, or \, psi)\) is still sometimes used as a measure of tire pressure, and millimeters of mercury (mm Hg) is still often used in the measurement of blood pressure. Pressure is defined for all states of matter but is particularly important when discussing fluids.
Example \(\PageIndex{1}\): Calculating Force Exerted by the Air - What Force Does a Pressure Exert?
An astronaut is working outside the International Space Station where the atmospheric pressure is essentially zero. The pressure gauge on her air tank reads \(6.9 \times 10^6 \, Pa\). What force does the air inside the tank exert on the flat end of the cylindrical tank, a disk 0.150 m in diameter?
Strategy
We can find the force exerted from the definition of pressure (Equation \red{pressure}) provided we can find the area \(A\) acted upon.
Solution
By rearranging the definition of pressure (Equation \red{pressure}) to solve for force, we see that
\[F = PA.\nonumber\]
Here, the pressure \(P\) is given, as is the area of the end of the cylinder \(A\), given by \(A = \pi r^2\). Thus
\[ \begin{align*} F &= (6.90 \times 10^6 \, Pa)(3.14)(0.0750 \, m)^2 \\[5pt] &= 1.22 \times 10^5 \, N. \end{align*}\]
Discussion
Wow! No wonder the tank must be strong. Since we found \(F = PA\), we see that the force exerted by a pressure is directly proportional to the area acted upon as well as the pressure itself.
The force exerted on the end of the tank is perpendicular to its inside surface. This direction is because the force is exerted by a static or stationary fluid. We have already seen that fluids cannot withstand shearing (sideways) forces; they cannot exert shearing forces, either.  The forces due to pressure have well-defined directions: they are always exerted perpendicular to any surface. (See the tire in Figure \(\PageIndex{2}\), for example.)
Finally, note that pressure is exerted on all surfaces. Swimmers, as well as the tire, feel pressure on all sides (Figure \(\PageIndex{3}\)).
PHET EXPLORATIONS: GAS PROPERTIES
Pump gas molecules in this simulation to a box and see what happens as you change the volume, add or remove heat, change gravity, and more. Measure the temperature and pressure, and discover how the properties of the gas vary in relation to each other.
Summary
- Pressure is the force per unit perpendicular area over which the force is applied. In equation form, pressure is defined as \[F = PA. \nonumber\]
- The SI unit of pressure is pascal and \(1 \, Pa = 1 \, N/m^2.\)
Glossary
- pressure
- the force per unit area perpendicular to the force, over which the force acts