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Reforms under President Woodrow Wilson - Exit Quiz
âThereâs No Such Thing as Sound Scienceâ by By Christie Aschwanden was a lead science writer for FiveThirtyEight. FiveThirtyEight, Science, Dec. 6, 2017 Science is being turned against itself. For decades, its twin ideals of transparency and rigor have been weaponized by those who disagree with results produced by the scientific method. Under the Trump administration, that fight has ramped up again. In a move ostensibly meant to reduce conflicts of interest, Environmental Protection Agency Administrator Scott Pruitt has removed a number of scientists from advisory panels and replaced some of them with representatives from industries that the agency regulates. Like many in the Trump administration, Pruitt has also cast doubt on the reliability of climate science. For instance, in an interview with CNBC, Pruitt said that âmeasuring with precision human activity on the climate is something very challenging to do.â Similarly, Trumpâs pick to head NASA, an agency that oversees a large portion the nationâs climate research, has insisted that research into human influence on climate lacks certainty, and he falsely claimed that âglobal temperatures stopped rising 10 years ago.â Kathleen Hartnett White, Trumpâs nominee to head the White House Council on Environmental Quality, said in a Senate hearing last month that she thinks we âneed to have more precise explanations of the human role and the natural roleâ in climate change. The same entreaties crop up again and again: We need to root out conflicts. We need more precise evidence. What makes these arguments so powerful is that they sound quite similar to the points raised by proponents of a very different call for change thatâs coming from within science. This other movement strives to produce more robust, reproducible findings. Despite having dissimilar goals, the two forces espouse principles that look surprisingly alike: Science needs to be transparent. Results and methods should be openly shared so that outside researchers can independently reproduce and validate them. The methods used to collect and analyze data should be rigorous and clear, and conclusions must be supported by evidence. These are the arguments underlying an âopen scienceâ reform movement that was created, in part, as a response to a âreproducibility crisisâ that has struck some fields of science.1 But theyâre also used as talking points by politicians who are working to make it more difficult for the EPA and other federal agencies to use science in their regulatory decision-making, under the guise of basing policy on âsound science.â Scienceâs virtues are being wielded against it. What distinguishes the two calls for transparency is intent: Whereas the âopen scienceâ movement aims to make science more reliable, reproducible and robust, proponents of âsound scienceâ have historically worked to amplify uncertainty, create doubt and undermine scientific discoveries that threaten their interests. âOur criticisms are founded in a confidence in science,â said Steven Goodman, co-director of the Meta-Research Innovation Center at Stanford and a proponent of open science. âThatâs a fundamental difference â weâre critiquing science to make it better. Others are critiquing it to devalue the approach itself.â Calls to base public policy on âsound scienceâ seem unassailable if you donât know the termâs history. The phrase was adopted by the tobacco industry in the 1990s to counteract mounting evidence linking secondhand smoke to cancer. A 1992 Environmental Protection Agency report identified secondhand smoke as a human carcinogen, and Philip Morris responded by launching an initiative to promote what it called âsound science.â In an internal memo, Philip Morris vice president of corporate affairs Ellen Merlo wrote that the program was designed to âdiscredit the EPA report,â âprevent states and cities, as well as businesses from passing smoking bansâ and âproactivelyâ pass legislation to help their cause. The sound science tactic exploits a fundamental feature of the scientific process: Science does not produce absolute certainty. Contrary to how itâs sometimes represented to the public, science is not a magic wand that turns everything it touches to truth. Instead, itâs a process of uncertainty reduction, much like a game of 20 Questions. Any given study can rarely answer more than one question at a time, and each study usually raises a bunch of new questions in the process of answering old ones. âScience is a process rather than an answer,â said psychologist Alison Ledgerwood of the University of California, Davis. Every answer is provisional and subject to change in the face of new evidence. Itâs not entirely correct to say that âthis study proves this fact,â Ledgerwood said. âWe should be talking instead about how science increases or decreases our confidence in something.â The tobacco industryâs brilliant tactic was to turn this baked-in uncertainty against the scientific enterprise itself. While insisting that they merely wanted to ensure that public policy was based on sound science, tobacco companies defined the term in a way that ensured that no science could ever be sound enough. The only sound science was certain science, which is an impossible standard to achieve. âDoubt is our product,â wrote one employee of the Brown & Williamson tobacco company in a 1969 internal memo. The note went on to say that doubt âis the best means of competing with the âbody of factââ and âestablishing a controversy.â These strategies for undermining inconvenient science were so effective that theyâve served as a sort of playbook for industry interests ever since, said Stanford University science historian Robert Proctor. The sound science push is no longer just Philip Morris sowing doubt about the links between cigarettes and cancer. Itâs also a 1998 action plan by the American Petroleum Institute, Chevron and Exxon Mobil to âinstall uncertaintyâ about the link between greenhouse gas emissions and climate change. Itâs industry-funded groupsâ late-1990s effort to question the science the EPA was using to set fine-particle-pollution air-quality standards that the industry didnât want. And then there was the more recent effort by Dow Chemical to insist on more scientific certainty before banning a pesticide that the EPAâs scientists had deemed risky to children. Now comes a move by the Trump administrationâs EPA to repeal a 2015 rule on wetlands protection by disregarding particular studies. (To name just a few examples.) Doubt merchants arenât pushing for knowledge, theyâre practicing what Proctor has dubbed âagnogenesisâ â the intentional manufacture of ignorance. This ignorance isnât simply the absence of knowing something; itâs a lack of comprehension deliberately created by agents who donât want you to know, Proctor said.2 In the hands of doubt-makers, transparency becomes a rhetorical move. âItâs really difficult as a scientist or policy maker to make a stand against transparency and openness, because well, who would be against it?â said Karen Levy, researcher on information science at Cornell University. But at the same time, âyou can couch everything in the language of transparency and it becomes a powerful weapon.â For instance, when the EPA was preparing to set new limits on particulate pollution in the 1990s, industry groups pushed back against the research and demanded access to primary data (including records that researchers had promised participants would remain confidential) and a reanalysis of the evidence. Their calls succeeded and a new analysis was performed. The reanalysis essentially confirmed the original conclusions, but the process of conducting it delayed the implementation of regulations and cost researchers time and money. Delay is a time-tested strategy. âGridlock is the greatest friend a global warming skeptic has,â said Marc Morano, a prominent critic of global warming research and the executive director of ClimateDepot.com, in the documentary âMerchants of Doubtâ (based on the book by the same name). Moranoâs site is a project of the Committee for a Constructive Tomorrow, which has received funding from the oil and gas industry. âWeâre the negative force. Weâre just trying to stop stuff.â Some of these ploys are getting a fresh boost from Congress. The Data Quality Act (also known as the Information Quality Act) was reportedly written by an industry lobbyist and quietly passed as part of an appropriations bill in 2000. The rule mandates that federal agencies ensure the âquality, objectivity, utility, and integrity of informationâ that they disseminate, though it does little to define what these terms mean. The law also provides a mechanism for citizens and groups to challenge information that they deem inaccurate, including science that they disagree with. âIt was passed in this very quiet way with no explicit debate about it â that should tell you a lot about the real goals,â Levy said. But whatâs most telling about the Data Quality Act is how itâs been used, Levy said. A 2004 Washington Post analysis found that in the 20 months following its implementation, the act was repeatedly used by industry groups to push back against proposed regulations and bog down the decision-making process. Instead of deploying transparency as a fundamental principle that applies to all science, these interests have used transparency as a weapon to attack very particular findings that they would like to eradicate. Now Congress is considering another way to legislate how science is used. The Honest Act, a bill sponsored by Rep. Lamar Smith of Texas,3 is another example of what Levy calls a âTrojan horseâ law that uses the language of transparency as a cover to achieve other political goals. Smithâs legislation would severely limit the kind of evidence the EPA could use for decision-making. Only studies whose raw data and computer codes were publicly available would be allowed for consideration. That might sound perfectly reasonable, and in many cases it is, Goodman said. But sometimes there are good reasons why researchers canât conform to these rules, like when the data contains confidential or sensitive medical information.4 Critics, which include more than a dozen scientific organizations, argue that, in practice, the rules would prevent many studies from being considered in EPA reviews.5 It might seem like an easy task to sort good science from bad, but in reality itâs not so simple. âThereâs a misplaced idea that we can definitively distinguish the good from the not-good science, but itâs all a matter of degree,â said Brian Nosek, executive director of the Center for Open Science. âThere is no perfect study.â Requiring regulators to wait until they have (nonexistent) perfect evidence is essentially âa way of saying, âWe donât want to use evidence for our decision-making,ââ Nosek said. Most scientific controversies arenât about science at all, and once the sides are drawn, more data is unlikely to bring opponents into agreement. Michael Carolan, who researches the sociology of technology and scientific knowledge at Colorado State University, wrote in a 2008 paper about why objective knowledge is not enough to resolve environmental controversies. âWhile these controversies may appear on the surface to rest on disputed questions of fact, beneath often reside differing positions of value; values that can give shape to differing understandings of what âthe factsâ are.â Whatâs needed in these cases isnât more or better science, but mechanisms to bring those hidden values to the forefront of the discussion so that they can be debated transparently. âAs long as we continue down this unabashedly naive road about what science is, and what it is capable of doing, we will continue to fail to reach any sort of meaningful consensus on these matters,â Carolan writes. The dispute over tobacco was never about the science of cigarettesâ link to cancer. It was about whether companies have the right to sell dangerous products and, if so, what obligations they have to the consumers who purchased them. Similarly, the debate over climate change isnât about whether our planet is heating, but about how much responsibility each country and person bears for stopping it. While researching her book âMerchants of Doubt,â science historian Naomi Oreskes found that some of the same people who were defending the tobacco industry as scientific experts were also receiving industry money to deny the role of human activity in global warming. What these issues had in common, she realized, was that they all involved the need for government action. âNone of this is about the science. All of this is a political debate about the role of government,â she said in the documentary. These controversies are really about values, not scientific facts, and acknowledging that would allow us to have more truthful and productive debates. What would that look like in practice? Instead of cherry-picking evidence to support a particular view (and insisting that the science points to a desired action), the various sides could lay out the values they are using to assess the evidence. For instance, in Europe, many decisions are guided by the precautionary principle â a system that values caution in the face of uncertainty and says that when the risks are unclear, it should be up to industries to show that their products and processes are not harmful, rather than requiring the government to prove that they are harmful before they can be regulated. By contrast, U.S. agencies tend to wait for strong evidence of harm before issuing regulations. Both approaches have critics, but the difference between them comes down to priorities: Is it better to exercise caution at the risk of burdening companies and perhaps the economy, or is it more important to avoid potential economic downsides even if it means that sometimes a harmful product or industrial process goes unregulated? In other words, under what circumstances do we agree to act on a risk? How certain do we need to be that the risk is real, and how many people would need to be at risk, and how costly is it to reduce that risk? Those are moral questions, not scientific ones, and openly discussing and identifying these kinds of judgment calls would lead to a more honest debate. Science matters, and we need to do it as rigorously as possible. But science canât tell us how risky is too risky to allow products like cigarettes or potentially harmful pesticides to be sold â those are value judgements that only humans can make.
What is a crime A crime is generally defined as an act or omission that is prohibited by criminal law Two critical ingredients of a crime are: 1) the commission of an act (Actus reus) 2) the mental intent to commit the act (Mens rea) A crime occurs when a person Commits an act or fails to commit an act when under a legal responsibility to do so Has the intent or mens rea to commit the act Does not have a legal defence or justification for committing the act and Violates a provision in criminal law The Social construction of crime Important to distinguish between behaviours that may be considered deviant by society and crimes Deviance is behaviour that is contrary to the norms and values of the larger society Crime is behaviour that breaks the law Deviance includes: Criminal behaviour and Wide range of other behaviours not against the law: May be frowned upon by the larger society What is viewed as deviant changes over time Crime includes: Social construction of crime Legal status of behaviours is not determined by behaviour itself but result of social response to the behaviour/persons/groups engaged in it Criminologists often conduct historical analyses to understand how social, economic and political environments may influence legislation Moral entrepreneurs Often play a key role in criminalizing certain activities Individuals, groups or organizations, seek action against certain groups of people/behaviours and bring pressure on legislators to enact criminal statutes The Origins and Application of the Criminal Law Differing perspectives on where criminal laws come from/ applied via the criminal justice system are reflected in two models 1) Value consensus model 2) Conflict Model Value consensus model Behaviours are defined as criminal/punishment imposed, reflect opinions/limits of tolerance Application of law, society reaffirms acceptable behaviours/social cohesion Conflict Model Crime and punishment reflect the power some groups have to influence, formulation/application of criminal law rich/privileged have an advantage in influencing law reform/criminal justice system The Canadian Legal System Is a common law system, with exception of Quebec which has a civil law system (Based on the French Code Napoleon) Common law is law based on custom, tradition, practice and generally unwritten Precedent is a judicial decision may be use as a standard in subsequent similar cases Canadian Courts Canadian courts organised in a hierarchy Supreme court of Canada is the highest court Stare decisis- principle whereby higher courts set precedents that lower courts must follow âTo stand by what was decidedâ Like cases should be treated alike All courts below SSC bound to apply that same ruling in subsequent cases Criminal Law Body of law deals with conduct considered so harmful to society as a whole that it is prohibited by statute and prosecuted and punished by the government Functions of the Criminal Law In Canadian society, Criminal law provides the following functions Acts as a mechanism of social control Defines the parameters of acceptable behaviour Reduces the risk of personal retaliation Assists in general and specific deterrence Prosecutes criminalized behaviour Protects groups interests Principles of Canadian Law The Rule of Law The requirement that governments as well as individuals be subjected to Traced back to the English Magna Carta The essence of the rule of law is that No one person is above the law All persons are bound by the law All are entitled to protection by the law The law should be observed and enforced equally There is a standard to which criminal justice officials must adhere and will be held accountable Criminal Law Vs. Civil (Tort) Law Summary Crime is a social construction and is a reflection of changing time and mores Criminal law is not static and what behaviour legislatively defined as criminal can change overnight There are instances in which controversy arises when the criminal law is applied to issues of ethics, morality and religion The criminal law was identified as one type of public law and the functions of the criminal law were set out The rule of law and the charter of rights and freedoms are two key parts of the foundation of the criminal justice system There are several principles that also provide the foundation for Canadian law The role, principles origins and application of the criminal law were examined and a number of case studies were presented to illustrate the dynamic nature of the criminal law in a diverse society
New Trends in Agriculture Extension approaches Extension has been, and still is, under attack from a wide spectrum of politicians and economists over its cost and financing. As a result, Extension Systems have had to make changes, by restating the systemâs mission, developing a new vision for the future, and formulating plans for the necessary transition to achieve the desired change. 1. Privatization of Agricultural Extension Service Privatization: Process of funding and delivering the extension services by private individual or organization is called Private Extension. Concept: Privatization of extension refers to services rendered in rural area & allied aspects of extension personnel working in private agencies or organization for which farmers are expected to pay a fee & it can be viewed as supplementary or alternative to public extension services (Sarvanan & Shivalinge 1980). Privatization approaches ⢠Share cropping system ⢠Village extension contract system ⢠Public extension through private delivery ⢠Service for vouchers Strengths of Private Extension System ⢠More demand - driven rather than supply â driven ⢠High quality of services in terms of satisfying information needs of clientele, trained manpower, sustained finances and resource allocation ⢠Provides for an information mix and choices available to farmers ⢠Enhanced efficiency of staff ⢠Assure continuous supply and quality agricultural products ⢠More effective because farmer can select an adviser who is the best able to help ⢠Healthy competition among service provider will lead to better quality and lower costs for service Weakness of Private Extension System ⢠Concentrate on area having favorable physical environment ⢠More face-to-face contacts (person oriented) ⢠Increased dependence of farmers and hence exploitation ⢠No education role ⢠Deprivation of small farmers ⢠Hamper the free flow of information 2. Cyber Extension or e-extension Concepts Cyber space: it is the imaginary or virtual space of computers connected with each other on Networks, across the Globe. Cyber extension: it means 'using the power of online networks, computer communications and digital interactive multimedia to facilitate dissemination of agriculture technology. Cyber Extension thus can be defined as the extension over cyber space. Important tools of cyber extension E-Mail, Telnet, File Transfer Protocol (FTP), Gopher, Archie and World Wide Web (WWW) Strengths of Cyber Extension ⢠Access to the astounding information and continuously available ⢠Information rich and instantaneously available of information ⢠Interactive communication ⢠The information is available from any point on the globe ⢠Communication is dynamic ⢠Cut steps from traditional process ⢠Save money, time and effort ⢠Multiplicity of purpose Issues and Concerns of Cyber Extension ⢠Lack of Reliable Telecom Infrastructure in Rural Areas ⢠Erratic or no Power Supply ⢠Lack of ICT Trained manpower (willing to serve) in Rural Areas ⢠Lack of content (locally relevant and in local languages) ⢠Lack of Information Services to Rural Clientele ⢠Low Purchasing power of the Rural communities ⢠Lack of Holistic Approaches ⢠Issues of Sustainability Application of cyber extension ⢠Village information shops Dr. M.S. SwaminathanResearch Foundation, Chennai ⢠Information villagers MANAGE in Ranga Reddy District in Andhra pradesh ⢠Gyandoot net initiative of District Dhar, Madhya Pradesh. ⢠Warna wired village of National Informatics Center (NIC) in Kolhapur- Sangli Districts of Maharashtra 3. Market-Led-Extension (MLE) Concepts Market: A congregation of prospective buyers & sellers with a common motive of trading a particular commodity. Extension: It is the spreading/reaching out to the mass Market-led-extension: Agriculture & economics coupled with extension is the perfect blend for reaching at the door steps of common man with the help of technology. Dimensions of market-led extension ⢠Marketing mix: A planned mix of the controllable elements of a product's marketing plan commonly termed as 4Ps: product, price, place, and promotion. These four elements are adjusted until the right combination is found that serves the needs of the product's customers, while generating optimum income. ⢠Marketing plan: A marketing plan is a comprehensive document that outlines a business and marketing efforts for the coming year. It describes business activities involved in accomplishing specific marketing objectives within a set time frame. A marketing plan also includes a description of the current marketing position of a business, a discussion of the target market and a description of the marketing mix that a business will use to achieve their marketing goals. ⢠Market Intelligence: It is the information relevant to a companyâs markets, gathered and analyzed specifically for the purpose of accurate and confident decision making. Market intelligence includes the process of gathering data from the companyâs external environment, whereas the business intelligence process is primarily based on internal recorded events â such as sales, shipments and purchases. ⢠Market oriented production ⢠Use of Technology Strengths of market-led extension ⢠SWOT analysis of the market ⢠Organization of Farmersâ Interest Groups (FIGs) ⢠Enhancing the interactive and communication skills of the farmers ⢠Establishing marketing and agro-processing linkages ⢠Advice on product planning ⢠Educating the farming community ⢠Direct marketing ⢠Acquiring complete market intelligence ⢠Publication of agricultural market information Production of video films of success stories ⢠Challenges to market-led extension ⢠Gigantic size of extension system ⢠Information technology Diverse conditions ⢠Market intelligence ⢠Reforms in agricultural extension system Government Initiatives ⢠Central warehousing Corporation-1965 ⢠MSP by Commission for Agricultural Cost and Price (CACP) ⢠Food Corporation of India ⢠Then some others as: Cotton Corporation of India (CCI), Jute Corporation of India (JCI), National Dairy Development Board (NDDB), Agriculture and Processed food Export Development Authority (APEDA) etc. 4. Farmer--Led-Extension (FLE) Farmer--led-extension is defined as 'the provision of training by farmers to farmers, often through the creation of a structure of farmer promoters and farmer trainers' (Scarborough et al., 1997). Philosophy and principles ⢠Farmers and local institutions (e.g. producer organizations or village leaders) should play a key role in selecting farmer-trainers and monitoring and evaluating them. This helps make the programmes more accountable to the community or groups that they serve. ⢠Farmer-trainers are âof the communityâ; they communicate in local languages and are more sensitive to local cultures, mannerisms, farming practices, and farmersâ needs. ⢠Farmer-trainers should be selected on the basis of their skills and interest in sharing information, not just on their farming expertise. ⢠Farmer-trainers need strong linkages with and support from development agents (whether government, non-government organization (NGO), or private), the people who train and backstop them. Farmer-trainers generally serve as a complement to existing extension systems, rather than being a substitute for them. ⢠Facilitating organizations and local institutions need to be proactive in ensuring that women as well as men become farmer-trainers. ⢠Simple and appropriate reference materials should be made available to the farmer trainers. Essential Elements of Farmer--led-extension ⢠The group ⢠The Field ⢠The Facilitator ⢠The curriculum ⢠Programme leader ⢠Financing Special features of Farmer--led-extension ⢠All learning is field based & it is primary venue for learning ⢠FLE group learning constantly over the experimentation period ⢠FLE promotes healthy decisions & quality decisions ⢠Farmers conduct their own field studies with comparisons or treatments ⢠Facilitates Farmer-to-Farmer communication ⢠Field staff serve as facilitators ⢠FLE is a unique way to educate farmers ⢠It is an effective platform for sharing of experiences and collectively solving agriculture related problems. 5. Expert system Expert system is an intelligent computer program that uses knowledge and inferences procedures to solve problems (Daniel Hunt, 1986). Objectives of developing expert system ⢠To enhance the performance of agricultural extension personnel and farmer ⢠To make farming more efficient and profitable ⢠To reduce the time required in solving the problems ⢠To maintain the expert system by continuously upgrading the database Advantages of expert system ⢠Solves critical problems by making logical deductions without taking much time ⢠It combines experimental and conventional knowledge with the reasoning skills of specialists ⢠To enhance the performance of average worker to the level of an expert Limitations of expert system ⢠Expensive computer program ⢠Mostly developed not in regional languages ⢠Requires AC power and internet connection all the time ⢠Complex software requires computer skilled personnel Modules of expert system in agriculture ⢠COMAX: Integrated crop management in cotton ⢠SOYEX: Soybean oil extraction expert system ⢠PLANT/ds: Diagnosis of soybean diseases ⢠MAIZE: Maize expert system for field crop management ⢠SEMAGI: Weed control decision making in sunflowers ⢠Rice Crop Doctor: Developed by National Institute of Agricultural Extension Management (MANAGE) Difference between conventional and expert system of extension Conventional Extension ⢠Universal approachability of same information is a problem ⢠Information is given whatever is available without considering needs and resources ⢠No Cost benefit analysis ⢠Information flow depends on availability of agent ⢠Require users to draw their own conclusion from facts Expert System of Extension ⢠Universal approachability of same information is possible ⢠Information is chosen based on their needs and resources ⢠Cost benefit analysis ⢠Information through Cyber Cafe at any place at any time ⢠Conclusion is drawn based on the decision given by the expert
Introduction to Decolonization and Nationalism Lesson Vocabulary colony (n) an area over which a foreign nation or state extends or maintains control. colonize (v) to take control of(a people or area, especially as an extension of state power. control (v) to exercise restraining or directing influence over. decolonize (v) to free or give up control of a colonized people or area. empire (n) a major political unit having a territory of great extent or a number of territories or peoples under a single sovereign authority. Ex. Roman Empire, Ottoman Empire human rights (n) rights (such as freedom from unlawful imprisonment, torture, and execution) regarded as belonging fundamentally to all people. imperialism (n) the policy, practice, or advocacy of extending the power and dominion of a nation, especially by direct territorial acquisitions or by gaining indirect control over the political or economic life of other areas. independence (n) a state of being free from direct control by others. majority (n) being over 50% of a population OR the group with the greater amount of power in a political entity. minority (n) being less than 50% of a population OR the group with less power than the majority in a political entity. nation (n) a politically organized group of people with shared characteristics, such as language, culture, or geographic origins. nationalism (n) a movement that seeks to unify or promote the interests of a nation or national group. nonviolence (n) a movement that completely abstains or avoids violence as a means of political protest. oppress (v) to crush or burden by abuse of power or authority. political movement (n) a group of people who seek to organize people to change government, policy, or social values. protest (n) an organized public demonstration of disapproval. reform (n) removal or correction of errors or of an abuse or a wrong. state (n): an organization that has a system in which a politically organized group of people have primary control over a definite territory. Definitions mostly used: Merriam-Webster
Cohesion and Adhesion Water molecules stick to each other as a result of hydrogen bond- ing. An attractive force that holds molecules of a single substance together is known as cohesion. Cohesion due to hydrogen bonding between water molecules contributes to the upward movement of water from plant roots to their leaves. Related to cohesion is the surface tension of water. The cohe- sive forces in water resulting from hydrogen bonds cause the mol- ecules at the surface of water to be pulled downward into the liquid. As a result, water acts as if it has a thin âskinâ on its sur- face. You can observe waterâs surface tension by slightly overfill- ing a drinking glass with water. The water will appear to bulge above the rim of the glass. Surface tension also enables small crea- tures such as spiders and water-striders to run on water without breaking the surface. Adhesion is the attractive force between two particles of differ- ent substances, such as water molecules and glass molecules. A related property is capillarity (KAP-uh-LER-i-tee), which is the attrac- tion between molecules that results in the rise of the surface of a liquid when in contact with a solid. Together, the forces of adhe- sion, cohesion, and capillarity help water rise through narrow tubes against the force of gravity. Figure 2-11 shows cohesion and adhesion in the water-conducting tubes in the stem of a flower. Temperature Moderation Water has a high heat capacity, which means that water can absorb or release relatively large amounts of energy in the form of heat with only a slight change in temperature. This property of water is related to hydrogen bonding. Energy must be absorbed to break hydrogen bonds, and energy is released as heat when hydrogen bonds form. The energy that water initially absorbs breaks hydro- gen bonds between molecules. Only after these hydrogen bonds are broken does the energy begin to increase the motion of the water molecules, which raises the temperature of the water. When the temperature of water drops, hydrogen bonds reform, which releases a large amount of energy in the form of heat. Therefore, during a hot summer day, water can absorb a large quantity of energy from the sun and can cool the air without a large increase in the waterâs temperature. At night, the gradually cooling water warms the air. In this way, the Earthâs oceans stabilize global temperatures enough to allow life to exist. Waterâs high heat capac- ity also allows organisms to keep cells at an even temperature despite temperature changes in the environment. As a liquid evaporates, the surface of the liquid that remains behind cools down. A relatively large amount of energy is absorbed by water during evaporation, which significantly cools the surface of the remaining liquid. Evaporative cooling prevents organisms that live on land from overheating. For example, the evaporation of sweat from a personâs skin releases body heat and prevents over- heating on a hot day or during strenuous activity. Adhesion Cohesion Hydrogen bonds Cohesion, adhesion, and capillarity contribute to the upward movement of water from the roots of plants. FIGURE 2â11 www.scilinks.org Topic: Hydrogen Bonding Keyword: HM60777 mb06se_cols03.qxd 5/18/07 10:47 AM Page 41 42 CHAPTER 2 Density of Ice Unlike most solids, which are denser than their liquids, solid water is less dense than liquid water. This property is due to the shape of the water molecule and hydrogen bonding. The angle between the hydrogen atoms is quite wide. So, when water forms solid ice, the angles in the molecules cause ice crystals to have large amounts of open space, as shown in Figure 2-12. This open space lattice structure causes ice to have a low density. Because ice floats on water, bodies of water such as ponds and lakes freeze from the top down and not the bottom up. Ice insulates the water below from the cold air, which allows fish and other aquatic crea- tures to survive under the icy surface.
Reforms & Manifest Destiny
Reforms in Education and Child Labor - Starter Quiz