29.10: Abstract Expressionism
The Development of Abstract Expressionism
Abstract expressionism was an American, post–World War II art movement.
Explain the abstract expressionist movement of the 1940s
Key Points
- Abstract expressionism has an image of being rebellious, anarchic, highly idiosyncratic, and nihilistic. In practice, the term is applied to any number of artists working (mostly) in New York who had quite different styles, and even to work that is neither especially abstract nor expressionist.
- Although it is true that spontaneity or the impression of spontaneity characterized many of the abstract expressionists works, most of these paintings involved careful planning, especially since their large size demanded it.
- Abstract expressionist paintings share certain characteristics, including the use of large canvases and an all-over approach, in which the whole canvas is treated with equal importance.
Key Terms
- New York School : The New York School (synonymous with abstract expressionist painting) was an informal group of American poets, painters, dancers, and musicians active in the 1950s and 1960s in New York City.
Abstract Expressionism Overview
Abstract expressionism was an American post–World War II art movement. Although the term abstract expressionism was first applied to American art in 1946 by the art critic Robert Coates, it had been used previously in Germany’s Der Sturm magazine in 1919.
Abstract expressionism is derived from the combination of the emotional intensity and self-denial of the German expressionists with the anti-figurative aesthetic of the European abstract schools, such as futurism, the Bauhaus, and synthetic cubism. Additionally, it has an image of being rebellious, anarchic, highly idiosyncratic, and nihilistic. In practice, the term is applied to any number of artists who worked (mostly) in New York during the 1940s.
Abstract expressionism has many stylistic similarities to the Russian artists of the early 20th century, such as Wassily Kandinsky. Although it is true that spontaneity or the impression of spontaneity characterized many of the abstract expressionists’ works, in reality most of these paintings involved careful planning, especially since their large size demanded it. In many instances, abstract art implied the expression of ideas that concern the spiritual, the unconscious, and the mind.
Characteristics of Abstract Expressionist Painting
Abstract expressionism expanded and developed the definitions and possibilities that artists had available in the creation of new works of art. Although abstract expressionism spread quickly throughout the United States, the major centers of this style were New York and California. Abstract expressionist paintings share certain characteristics, including the use of large canvases and an all-over approach, in which the whole canvas is treated with equal importance (as opposed to the center being of more interest than the edges).
Jackson Pollock’s energetic action paintings, with their busy feel, are different both technically and aesthetically from the violent and grotesque Women series of Willem de Kooning. In contrast to the emotional energy and gestural surface marks of Pollock and de Kooning, the color-field painters initially appeared to be cool and austere, eschewing the individual mark in favor of large, flat areas of color, which these artists considered to be the essential nature of visual abstraction, along with the actual shape of the canvas. In later years, color-field painting has proven to be both sensual and deeply expressive, albeit in a different way from gestural abstract expressionism.
New York
During the period leading up to and during World War II, modernist artists, writers, and poets, as well as important collectors and dealers, fled Europe and the onslaught of the Nazis for safe haven in the United States. New York replaced Paris as the new center of the art world.
The 1940s in New York City heralded the triumph of American abstract expressionism—a modernist movement that combined lessons learned from Henri Matisse, Pablo Picasso, Surrealism, Joan Miró, Cubism, Fauvism, and early Modernism via the great teachers who arrived in America, like Hans Hofmann from Germany and John D. Graham from Russia.
Graham’s influence on American art during the early 1940s was particularly visible in the work of Arshile Gorky, Willem de Kooning, and Jackson Pollock. Gorky’s contributions to American and world art are difficult to overestimate. His works—such as The Liver is the Cock’s Comb, The Betrothal II, and One Year the Milkweed—immediately prefigured abstract expressionism.
Jackson Pollock
During the late 1940s, Jackson Pollock’s radical approach to painting revolutionized the potential for all contemporary art that followed him. To some extent, Pollock realized that the journey toward making a work of art was as important as the work of art itself.
Pollock redefined what it was to produce art. His move away from easel painting and conventionality was a liberating signal to the artists of his era and to all that came after. Artists realized that Jackson Pollock’s process—the placing of unstretched raw canvas on the floor where it could be attacked from all four sides using artist materials and industrial materials—essentially took making art beyond any prior boundary.
Jackson Pollock and Action Painting
Action painting, created by Jackson Pollock, is a style in which paint is spontaneously splattered, smeared, or dripped onto the canvas.
Describe Jackson Pollock’s method of action painting
Key Points
- Action painting was developed as part of the abstract expressionism movement that took place in post–World War II America, especially in New York, during the 1940s through until the early 1960s.
- Action painting places the emphasis on the act of painting rather than the final work as an artistic object.
- Jackson Pollock challenged traditional conventions of painting by using synthetic, resin-based paints, laying his canvas on the floor, and using hardened brushes, sticks, and even basting syringes to apply paint.
Key Terms
- abstract : Art that does not depict objects in the natural world, but instead uses color and form in a non-representational way.
- aesthetic : Concerned with beauty, artistic impact, or appearance.
Action Painting
Action painting is a style of painting in which paint is spontaneously dribbled, splashed, or smeared onto the canvas, rather than being carefully applied with a brush. The resulting work often emphasizes the physical act of painting itself as an essential aspect of the finished work.
Action painting is inextricably linked to abstract expressionism, a school of painting popular in post-World War II America that was characterized by the view that art is non-representational and chiefly improvisational. The major artists associated with this movement are Jackson Pollock, Willem de Kooning, Robert Motherwell, Franz Kline, and Mark Rothko, among others.
The term action painting was coined by the American art critic Harold Rosenberg in 1952 in his essay The American Action Painters, signaling a major shift in the aesthetic perspective of the New York School painters and critics. According to Rosenberg, the canvas was not an object, but rather “an arena in which to act. ”
Rosenberg’s critique shifted the emphasis from the object to the struggle of painting itself, with the finished work being only the physical manifestation, a kind of residue, of the actual work of art, which was in the process of the painting’s creation.
Action painting refers to the spontaneous activity that was the action of the painter—through arm and wrist movement, painterly gestures— and led to paint that was thrown, splashed, stained, splattered, poured, and dripped. The painter would sometimes let the paint drip onto the canvas while rhythmically dancing or even while standing on top of the unstretched canvas laying on the floor—both techniques invented by one of the most important abstract expressionists: Jackson Pollock.
Jackson Pollock
Born in Cody, Wyoming in 1912, Jackson Pollock moved to New York City in 1930, where he studied under Thomas Hart Benton at the Art Students League of New York. In 1948 he married the American painter Lee Krasner, and they moved to what is now known as the Pollock-Krasner House and Studio in the Springs area of East Hampton, Long Island, NY.
Materials and Process
After his move to Springs, he began painting with his canvases laid out on the studio floor, turning to synthetic, resin-based paints called alkyd enamels. These were much more fluid than traditional paint and, at that time, were a novel medium. Pollock described his use of household paints, instead of fine art paints, as “a natural growth out of a need.”
He used hardened brushes, sticks, and even basting syringes as paint applicators. By defying the convention of painting on an upright surface, he added a new dimension by being able to view and apply paint to his canvases from all directions—the term all-over painting has been used to describe some of his work, as well as the work of other artists from that time.
In the process of making paintings in this way, he moved away from figurative representation, and challenged the Western tradition of using easel and brush. In addition, he also moved away from the use of only the hand and wrist, since he used his whole body to paint.
Titles with Numbers
Pollock wanted an end to the search for figurative elements in his paintings, so he abandoned titles and started numbering his paintings instead. The numbering relates to the way composers title their works. Furthering the musical metaphor, Pollock’s action paintings have been often described as improvisational works of art, similar to how jazz musicians approach the performance of a piece.
Death
At the peak of his fame, Pollock abruptly abandoned the drip style and by 1951 his works had turned darker in color. This was followed by a return to color, and he reintroduced figurative elements. During this period Pollock moved to a more commercial gallery and there was great demand from collectors for his new paintings.
In response to this pressure, along with personal frustration, his long-term problem with alcoholism worsened. He painted his two last works in 1955. On August 11, 1956, Pollock died in a single-car crash in his Oldsmobile convertible while driving under the influence of alcohol.
After Pollock’s demise at age 44, his widow, Lee Krasner, managed his estate and ensured that Pollock’s reputation remained strong despite changing art-world trends. They are both buried in Green River Cemetery in Springs, Long Island, NY.
Color-Field Painting
Color-field painting can be recognized by its large fields of solid color spread across or stained into the canvas to create areas of unbroken surface and a flat picture plane.
Differentiate color-field painting from other contemporary abstract art such as abstract expressionism
Key Points
- Color-field painting is a style of abstract painting that emerged in New York City during the 1950s and 1960s. It is closely linked to abstract expressionism, post-painterly abstraction, and lyrical abstraction.
- Distinct from the emotional energy and gestural surface marks and paint handling seen in the work of abstract expressionists like Jackson Pollock, color-field painting came across as cool and austere.
- The movement places less emphasis on gesture, brushstrokes, and action in favor of an overall consistency of form and process, with color itself becoming the subject matter.
- Mark Rothko, Frank Stella, Clyfford Still, Barnett Newman, Adolph Gottlieb, and Morris Louis are among the many artists who used color-field techniques in their work.
- Color-field painters revolutionized the way paint could be effectively applied, through their use of acrylic paint and techniques such as staining and spraying.
Key Terms
- abstract expressionism : An American genre of modern art that used improvised techniques to generate highly abstract forms.
- action painting : A genre of modern art in which the paint is dribbled, splashed, or poured onto the canvas to obtain a spontaneous and totally abstract image.
- lyrical abstraction : A type of abstract painting related to abstract expressionism; in use since the 1940s.
Color-Field Painting
Color-field painting is a style of abstract painting that emerged in New York City during the 1950s and 1960s. Inspired by European modernism and closely related to abstract expressionism, many of its notable early proponents were among the pioneering abstract expressionists.
Color-field is characterized primarily by its use of large fields of flat, solid color spread across or stained into the canvas to create areas of unbroken surface and a flat picture plane. The movement places less emphasis on gesture, brushstrokes, and action than abstract expressionism, favoring instead an overall consistency of form and process, with color itself becoming the subject matter.
Encompassing several decades from the mid-20th century through the early 21st century, the history of color-field painting can be separated into three separate but related generations of painters:
- Abstract expressionism.
- Post-painterly abstraction.
- Lyrical abstraction.
Some of the artists made works in all three eras that relate to all of the three styles.
Clement Greenberg
The focus of attention in the contemporary art world began to shift from Paris to New York after World War II and the development of American Abstract Expressionism. During the late 1940s and early 1950s, Clement Greenberg was the first art critic to suggest and identify a dichotomy between differing tendencies within the abstract expressionist canon—especially between action painting and what Greenberg termed post-painterly abstraction (today known as color-field).
Color-Field Formats
By the late 1950s and early 1960s, young artists began to break away stylistically from abstract expressionism, experimenting with new ways of handling paint and color. Moving away from the gesture and angst of action painting towards flat, clear picture planes and a seemingly calmer language, color-field artists used formats of stripes, targets, and simple geometric patterns to concentrate on color as the dominant theme their paintings.
Color-field painting initially referred to a particular type of abstract expressionism, exemplified especially in the work of Mark Rothko, Clyfford Still, Barnett Newman, Robert Motherwell, Adolph Gottlieb and several series of paintings by Joan Miró.
Color-field painting sought to rid art of superfluous rhetoric and gesture. Artists like Morris Louis, Jules Olitski, Kenneth Noland, Friedel Dzubas, and Frank Stella often used greatly reduced formats, simplified or regulated systems, and basic references to nature to draw the focus of the painting to color, and the interactions of color, as the most important element.
An important distinction between color-field painting and abstract expressionism is the way paint is handled. The most basic defining technique of painting is the application of paint, and the color-field painters revolutionized the way paint could be effectively applied.
Water-soluble, artist-quality acrylic paints first became commercially available in the early 1960s, coinciding with the color-field movement. The most common applications were:
- Stain painting, where artists mix and dilute their paint in buckets or coffee cans to make it a more fluid liquid, then pour it onto raw, unprimed canvas and draw shapes and areas as they stain.
- Spray painting, a technique using a spray gun to create large expanses and fields of color sprayed across the canvas.
- The use of stripes.
Color-field painting initially appeared to be cool and austere due to these methods of handling paint that tended to eschew the individual mark of the artist. However, color-field painting has proven to be both sensual and deeply expressive, albeit in a different way from gestural abstract expressionism.
The New York School
The New York School was an informal group of American abstract painters and other artists that was active in the 1950s and 1960s.
Explain what the New York School is known for and who its proponents were
Key Points
- The New York School was an informal group of abstract painters and other artists in NYC though it has become associated most with the abstract expressionist movement. Although abstract expressionism spread quickly throughout the United States, the major centers of this style were New York City and California.
- New York School artists drew inspiration from surrealism and contemporary art movements such as action painting, abstract expressionism, jazz, improvisational theater, and experimental music.
- The work of the New York School was documented through annual exhibitions of painting and sculpture from 1951–1957, most notably in the 9th Street Art Exhibition.
- In addition to painting, the New York School was associated with many poets, dancers, composers, jazz musicians, and writers.
Key Terms
- surrealism : An artistic movement and an aesthetic philosophy, pre-dating abstract expressionism, that aims for the liberation of the mind by emphasizing the critical and imaginative powers of the subconscious.
- GI Bill : The Servicemen’s Readjustment Act of 1944, known informally as the GI Bill, was a law that provided a range of benefits for returning World War II veterans (commonly referred to as GIs).
- abstract expressionism : An American genre of modern art that used improvised techniques to generate highly abstract forms.
The New York School
The New York School was an informal group of American poets, painters, dancers, and musicians that was active in the 1950s and 1960s in New York City. It represented, and is often synonymous with, the art movement of aAbstract expressionism, such as the work of Jackson Pollack and Willem de Kooning.
The artists of the New York School drew their inspiration from surrealism and other contemporary, avant-garde art movements, in particular action painting, abstract expressionism, jazz, improvisational theater, experimental music, and the interaction of friends in the New York City art world’s vanguard circle.
Abstract Expressionism
A school of painting that flourished after World War II until the early 1960s, abstract expressionism is characterized by the view that art is non-representational and chiefly improvisational. Abstract expressionist paintings share certain characteristics, including the use of large canvases, and an all-over approach whereby the whole canvas is treated with equal importance (as opposed to the center being of more interest than the edges). The canvas as the arena became a credo of action painting, while the integrity of the picture plane became a credo of the color-field painters.
The post-World War II era benefited some of the artists who were recognized early on by art critics. Some artists from New York, such as Norman Bluhm and Sam Francis, took advantage of the GI Bill and left for Europe, to return later with acclaim.
Many artists from all across the U.S. arrived in New York City to seek recognition, and by the end of the decade the list of artists associated with the New York School had greatly increased. Painters, sculptors, and printmakers created art that was termed action painting, fluxus, color-field painting, hard-edge painting, pop art, minimal art and lyrical abstraction, among other styles and movements associated with abstract expressionism.
9th Street Art Exhibition
The 9th Street Art Exhibition was held on May 21–June 10, 1951. It was a historical, ground-breaking exhibition that gathered a number of notable artists, and it was the stepping-out of the post-war New York avant-garde, collectively known as the New York School.
The show was hung by Leo Castelli, as he was liked by most of the artists and thought of as someone who would hang the exhibition without favoritism. The opening of the show was a great success. According to the critic, historian, and curator Bruce Altshuler, “It appeared as though a line had been crossed, a step into a larger art world whose future was bright with possibility.”
Interdisciplinary Influences in the New York School
In addition to painting, the New York School was associated with many poets, dancers, composers, jazz musicians, and writers. Poets drew on inspiration from surrealism and the contemporary avant-garde art movements, in particular the action painting of their friends in the New York City art world like Jackson Pollock and Willem de Kooning.
In the 1960s, the work of the avant-garde minimalist composers La Monte Young, Philip Glass, Tony Conrad, Steve Reich, and Terry Riley became prominent in the New York art world. The new bebop and cool jazz musicians in the 1940s and 1950s (such as Charlie Parker, Miles Davis, John Coltrane, and Gerry Mulligan) coincided with the New York School and abstract expressionism.
There are also commonalities among the New York School and members of the beat-generation poets who were active in the 1940s, 1950s, and 1960s in New York City, including Allen Ginsberg, Jack Kerouac, William S. Burroughs, Diane Wakoski, and several others.
Abstract Expressionist Sculpture
During the postwar period, many sculptors made work in the prevalent styles of the time: abstract expressionism, minimalism and pop art.
Evaluate how sculpture from 1945–1970 was influenced by abstract expressionism, minimalism, and pop art
Key Points
- Abstract expressionist sculpture was greatly influenced by surrealism and its emphasis on spontaneous or subconscious creation.
- Minimalist sculptures often set out to expose the essence or identity of a subject through the elimination of all non-essential forms or concepts. These works are often characterized by geometric, cubic forms, equality of parts, repetition, neutral surfaces, and the use of industrial materials.
- The sculptors Claes Oldenburg and George Segal were important proponents of pop art in their use of found-objects and how they reproduced everyday commercial objects as fine art.
Key Terms
- pop art : An art movement that emerged in the 1950s, that presented a challenge to traditions of fine art by including imagery from popular culture such as advertising, news, etc.
- found object : A natural object, or one manufactured for some other purpose, considered as part of a work of art.
Abstract Expressionism and Sculpture
While Abstract Expressionism is most closely associated with painting, a number of sculptors were integral to the movement as well. David Smith, Dorothy Dehner, Herbert Ferber, Isamu Noguchi, Ibram Lassaw, Theodore Roszak, Phillip Pavia, Mary Callery, Richard Stankiewicz, Louise Bourgeois, and Louise Nevelson in particular were considered to be important members of the movement.
Similar to abstract expressionist painting, sculptural work from the movement was greatly influenced by surrealism and its emphasis on spontaneous or subconscious creation. Abstract expressionist sculpture, like painting from the movement, was more interested in process than product, which can make it difficult to visually distinguish works by aesthetics alone, so it is important to take into account what the artist has to say about their process.
The sculptures of David Smith, for example, sought to express two-dimensional subjects that had never before been shown in three dimensions. His work blurred the distinctions between sculpture and painting, generally making use of delicate tracery rather than solid form, with a two-dimensional appearance that contradicted the traditional idea of sculpture in the round.
Minimalism
Minimalism during the 1960s and 1970s was a reaction against the painterly subjectivity of abstract expressionism that dominated the previous decades. Minimalist artists explicitly stated that their art was not about self-expression. Instead, Minimalist works often set out to expose the essence or identity of a subject through the elimination of all non-essential forms or concepts.
These works are often characterized by geometric, cubic forms, equality of parts, repetition, neutral surfaces, and the use of industrial materials. Some prominent artists who worked with sculpture and were associated with minimalism (though not all agreed with the association) include Donald Judd, John McCracken, Anthony Caro, Tony Smith, Sol LeWitt, Carl Andre, and Dan Flavin.
Dan Flavin
Dan Flavin was an American minimalist famous for creating sculptural objects and installations from commercially available fluorescent light fixtures. The lack of the mark of the artist’s hand in these cases speak to the notion of exposing the true form of the sculptural object, a significant tenet of the minimalist movement.
Donald Judd
Donald Judd, who disavowed the term minimalism, and preferred to refer to his sculptures as specific objects, used simple, repeated forms to explore space. His works were often fabricated (rather than sculpted) out of metals, industrial plywood and concrete, and therefore defied easy classification as sculpture.
Judd’s “Untitled,” 1977, applies the simplicity and geometric form typical of minimalist works. Fabricated from concrete, the piece comes across as potentially industrially created as it lacks the mark of the artist’s hand that is so often seen in works of art, favoring instead a cool austerity that highlights the qualities of the form and the material used to fabricate it.
Pop Art
There were numerous artists working in sculpture who were associated with the pop art movement. Two important examples are Claes Oldenburg and George Segal.
Claes Oldenburg
Oldenburg began his artistic practice as part of a group of artists reacting to Abstract Expressionism’s sublime gestures with figural drawings and papier mache sculptures. His artistic trajectory took him from making found-object paintings littered with urban debris to plaster sculptures of everyday commercial and manufactured objects. He subsequently created sculptures of similar subjects on larger and larger scales, first sewing soft sculptures out of canvas, then turning to large outdoor monuments in public spaces.
George Segal
George Segal, another artist associated with the pop-art movement, was best known for his life-size figures made from plaster and bandage casts. These figures, often left with minimal color and detail and given a ghostly, hollow appearance, inhabited tableaux constructed of found objects such as a street corner, a bus, or a diner.
Common practices seen in pop-art sculptural work include the display of found art objects, the representation of consumer goods, the placing of typical non-art objects within a gallery setting, and the abstraction of familiar objects. We can see this abstraction in such works as Plug by Oldenburg.
This reproduction of a familiar or mundane object is displayed at such an increased size that the subject matter becomes abstracted, its original function simultaneously altered and highlighted.
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- David Smith (sculptor). Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/David_Smith_(sculptor). License : CC BY-SA: Attribution-ShareAlike
- George Segal (artist). Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/George_Segal_(artist). License : CC BY-SA: Attribution-ShareAlike
- Minimalism (visual arts). Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Minimalism_(visual_arts). License : CC BY-SA: Attribution-ShareAlike
- Abstract expressionism. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Abstract_expressionism%23Major_paintings_and_sculpture. License : CC BY-SA: Attribution-ShareAlike
- Dan Flavin. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Dan_Flavin. License : CC BY-SA: Attribution-ShareAlike
- Claes Oldenburg. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Claes_Oldenburg. License : CC BY-SA: Attribution-ShareAlike
- Donald Judd. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Donald_Judd. License : CC BY-SA: Attribution-ShareAlike
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1.2: Gelatinization
Hydrocolloids
A hydrocolloid is a substance that forms a gel in contact with water. There are two main categories:
- Thermo-reversible gel: A gel that melts upon reheating and sets upon cooling. Examples are gelatin and agar agar.
- Thermo-irreversible gel: A gel that does not melt upon reheating. Examples are cornstarch and pectin.
Excessive heating, however, may cause evaporation of the water and shrinkage of the gel. Hydrocolloids do not hydrate (or dissolve) instantly, and that hydration is associated with swelling, which easily causes lumping. It is therefore necessary to disperse hydrocolloids in water. Classically, this has always been done with cornstarch, where a portion of the liquid from the recipe is mixed to form a “slurry” before being added to the cooking liquid. This can also be done with an immersion blender or a conventional blender, or by mixing the hydrocolloid with a helping agent such as sugar, oil, or alcohol prior to dispersion in water.
Starches
Starch gelatinization is the process where starch and water are subjected to heat, causing the starch granules to swell. As a result, the water is gradually absorbed in an irreversible manner. This gives the system a viscous and transparent texture. The result of the reaction is a gel, which is used in sauces, puddings, creams, and other food products, providing a pleasing texture. Starch-based gels are thermo-irreversible, meaning that they do not melt upon heating (unlike gelatin, which we will discuss later). Excessive heating, however, may cause evaporation of the water and shrinkage of the gel.
The most common examples of starch gelatinization are found in sauce and pasta preparations and baked goods.
- In sauces, starches are added to liquids, usually while heating. The starch will absorb liquid and swell, resulting in the liquid becoming thicker. The type of starch determines the final product. Some starches will remain cloudy when cooked; others will remain clear.
- Pasta is made mostly of semolina wheat (durum wheat flour), which contains high amounts of starch. When pasta is cooked in boiling water, the starch in the pasta swells as it absorbs water, and as a result the texture of the pasta softens.
Starch molecules make up the majority of most baked goods, so starch is an important part of the structure. Although starches by themselves generally can’t support the shape of the baked items, they do give bulk to the structure. Starches develop a softer structure when baked than proteins do. The softness of the crumb of baked bread is due largely to the starch. The more protein structure there is, the chewier the bread.
Starches can be fairly straightforward extracts of plants, such as cornstarch, tapioca, or arrowroot, but there are also modified starches and pre-gelatinized starches available that have specific uses. See Table 1 for a list of different thickening and binding agents and their characteristics.
| Starch or Gel | Ratio | Preparation | Characteristics and Uses |
|---|---|---|---|
| Cornstarch | 20-40 g starch thickens 1 L liquid |
A slurry (mixture of cornstarch and water) is mixed and added to a simmering liquid while whisking until it dissolves and the liquid thickens;
or
Cornstarch mixed with sugar, and cold liquid added Thickened mixture simmered until no starch taste remains |
Used to thicken sauces when a clear glossy texture is desired, such as dessert sauces and in Asian-inspired dishes
Translucent, thickens further as it cools; forms a “sliceable” gel Sensitive to extended heat exposure, so products become thin if held at heat for long periods of time |
| Waxy maize, waxy rice |
Dissolved in cold water
20-40 g starch thickens 1 L liquid |
Added to hot liquid while whisking until it dissolves and the liquid thickens |
Used in desserts and dessert sauces
Clear, does not thicken further as it cools Does not gel at cool temperatures, good for cold sauces Quite stable at extreme temperatures (heat and freezing) |
| Modified starches |
Dissolved in cold water
20-40 g starch thickens 1 L liquid |
Added to hot liquid while whisking until it dissolves and the liquid thickens |
Modified starches are often used in commercially processed foods and convenience products
Modified to improve specific characteristics (e.g., stability or texture under extreme conditions; heat and freezing) Translucent, thickens further as it cools |
| Pre-gelatinized starches |
Powder, dissolved in cold liquid
20-40 g starch thickens 1 L liquid |
Added to liquid at any temperature |
Used when thickening liquids that might lose colour or flavour during cooking
Become viscous without the need for additional cooking Translucent, fairly clear, shiny, does NOT gel when cold |
| Arrowroot |
Powder, dissolved in cold liquid
20-40 g starch thickens 1 L liquid |
Added to hot liquid while whisking until it dissolves and the liquid thickens |
Derived from cassava root
Used in Asian cuisines Very clear; possesses a gooey texture Translucent, shiny, very light gel when cold |
| Gelatin | 15-30 g gelatin sets 1 L liquid |
Powder or sheets (leaves) dissolved in cold water
Added to cold or simmering liquid Activates with heat, sets when cold |
Derived from collagens in bones and meats of animals
Used in aspic, glazes, cold sauces, and desserts Clear, firm texture Dissolves when reheated, thickens when cold |
| Agar agar | 15-30g agar agar sets 1 L liquid |
Powder dissolved in cold water
Added to cold or simmering liquid Activates with heat, sets when cold |
Extracted from seaweed
Used in Asian desserts and molecular gastronomy cooking Used in place of gelatin in vegetarian dishes Clear firm texture Does not thin when reheated, thickens more when cold |
Gelling agents
Gelatin is a water-soluble protein extracted from animal tissue and used as a gelling agent, a thickener, an emulsifier, a whipping agent, a stabilizer, and a substance that imparts a smooth mouth feel to foods. It is thermo-reversible, meaning the setting properties or action can be reversed by heating. Gelatin is available in two forms: powder and sheet (leaf).
Gelatin is often used to stabilize whipped cream and mousses; confectionery, such as gummy bears and marshmallows; desserts including pannacotta; commercial products like Jell-O; “lite” or low-fat versions of foods including some margarines; and dairy products such as yogurt and ice cream. Gelatin is also used in hard and soft gel capsules for the pharmaceutical industry.
Agar agar is an extract from red algae and is often used to stabilize emulsions or foams and to thicken or gel liquids. It is thermo-reversible and heat resistant.
It is typically hydrated in boiling liquids and is stable across a wide range of acidity levels. It begins to gel once it cools to around 40ºC (100ºF) and will not melt until it reaches 85ºC (185ºF).
Pectin
Pectin is taken from citrus and other tree fruits (apples, pears, etc.). Pectin is found in many different foods such as jam, milk-based beverages, jellies, sweets, and fruit juices. Pectin is also used in molecular gastronomy mainly as a gelling agent, thickener, and stabilizer.
There are a variety of types of pectin that react differently according to the ingredients used. Low-methoxyl pectin (which is activated with the use of calcium for gelling) and high-methoxyl pectin that requires sugar for thickening are the two most common types used in cooking. High-methoxyl pectin is what is traditionally used to make jams and jellies. Low-methoxyl pectin is often used in modern cuisine due to the thermo-irreversible gel that it forms and its good reaction to calcium. Its natural capability to emulsify and gel creates stable preparations.
Increasingly, cooks, bakers, and pastry chefs are turning to many different gels, chemicals, and other substances used in commercial food processing as new ingredients to modify liquids or other foods. These will be outlined in detail in the section on molecular gastronomy.


5.4: Non-Linear Optimization
As discussed earlier, most infrastructure management optimization problems are formulated as linear programming problems. However, in some cases, non-linear optimization may be needed. The general form of the non-linear optimization problem is:
\[\text{Minimize or Maximize } f(x) \text{ subject to } g_{i}(x) \leq 0 \text{ and } h_{j}(x)=0\]
Where \(x\) is a vector of decision variables, \(f(x)\) is a non-linear objective function, \(g_i(x)\) and \(h_j(x)\) are sets of constraints which may be linear or non-linear.
One source of non-linearities is that of scale economies in performing a maintenance or rehabilitation task. This might occur if there are fixed mobilization costs to undertake a task which are then spread over the amount of work. Components such as tanks also have scale economies since their volume grows faster than the (expensive) tank surface as the tank size increases. Figure 5.4.1 illustrates scale economies in two related graphs. In the upper graph, the cost per unit of work declining as the amount of work increases. In the lower graph, the total cost goes up slower than the increase in the amount of work.
Another source of non-linearity for infrastructure management comes from flow effects. For example, roadway traffic congestion is non-linear in that a small increase in traffic may result in large amounts of delay. With roadway maintenance blocking lanes of traffic, the capacity of the roadway network is reduced and congestion may increase considerably. Figure 5.4.2 illustrates the non-linear increase in average travel time.
Non-linear optimization has some pitfalls. First, solutions obtained may not be global optimum but only local maximum or minimum values of the objective function. Second, particular formulations may lead to physically impossible results. For example, in a case of scale economies, a non-linear optimization may wish to build the top few feet of a dam rather than the entire dam since the top two feet would hold more water back than average and would be cheaper to build!
Most non-linear optimization uses some form of a gradient
approach in which a set of feasible decision variable values are
chosen and then these are altered to improve the objective function
and still remain feasible. Solver in the spreadsheet program EXCEL
uses this type of technique. In many cases, it is useful to use
multiple starting points to reduce the chance of ending up with a
local optimum.
As an example of non-linear optimization useful for infrastructure
management, we can suggest a flow problem which can be applied to
traffic flow in road networks or water flow in pipe networks. The
costs of maintenance or rehabilitation work can be estimated by
comparing flow costs before and during network disruption. The same
approach can be used for assessing new capacity or operating
procedures. The problem appears in Hendrickson (1984).
We assume that a network exists with a set of nodes (intersections) N and arcs (pipe links or streets) A. There is a cost of flow on link \(ij\) \(f(y)\) which is assumed to be monotonically increasing as in Figure 5.4.2. This assumption is physically realistic and insures convexity for the problem-solution space making a solution easier.
The general problem of equilibrium flow is:
\[P1: \text { minimize } \sum_{(i, j) \in A} \int_{0}^{x_{i j}} f_{i j}(y) d y\]
subject to:
\[\sum_{(i, k) \in A} x_{i k}-\sum_{(k, j) \in A} x_{k j}=q_{k} \text { for all } k \in N\]
\[x_{i, j}>0 \text { for all }(i, j) \in A\]
Where \(x_{ij}\) is flow on link \(ij\) and \(qk\) is the net inflow or outflow at node k. The objective is to minimize ‘impedance’ of flow on each link, and the constraints conserve flow through nodes and require all flows to be positive.
For pipeline hydraulics applications, the flow would be fluid flow measured in volume per unit time. The impedance function would be head loss (or gain) per unit of distance. The impedance function should include elevation differences of nodes as well as pipe friction loss (through a function such as the Hazen-Williams function \(f(x) = k*x^m\).
For traffic networks, a slightly more complicated form of the problem must be used to keep track of flows between particular origins and destinations. The impedance is travel time and relates to total flow on link \(ij\). Problem P2 below shows the traffic flow problem with the rs notation for traffic from node r to node s, a constraint to insure conservation of flow through intersection nodes, and a constraint to aggregate the individual origin-destination flows for each link.
\[\text {P2: minimize } \sum_{(i, j) \in A} \int_{0}^{x_{i j}} f_{i j}(y) d y\]
\[\sum_{s \in A}\left[\sum_{(i, k) \in A} x_{i k}^{r s}-\sum_{(k, j) \in A} x_{k j}^{r s}\right]=q_{r k} \text { for all } k \in N, r \in N\]
\[\sum_{s \in N}^{r \in N} x_{i j}^{r s}=x_{i j} \text { for all }(i, j) \in A\]
For the traffic flow application, the solution set of flows represents a ‘user equilibrium solution’ in which the travel time on each path used between origin r and destination s has the same overall travel time (if not, travelers would change the path and reduce their travel time). Paths not used between origin r and destination s would have higher travel time and would be unattractive.
As noted earlier, the problem P2 could be solved to obtain travel times and flows on an existing network. After the network is altered due to construction, the equilibrium travel time after the alteration could then be modelled. Noted that in this simple application form, the origin-destination flow would not change. More elaborate analysis could relax this assumption to allow new destinations or other travel choices.
Gradient solution algorithms exist for problem P1 and P2 that can easily accommodate thousands of nodes and links. Author, (Hendrickson, 1984) presents one solution algorithm as well as additional applications of the model form to project task scheduling and structural analysis. Numerous software programs exist for this type of model formulation.


6.11A: Ecological Associations Among Microorganisms
Despite an apparent simplicity, bacteria can form complex associations with other organisms.
LEARNING OBJECTIVES
Contrast the ecological associations among microorganisms
Key Takeaways
Ecological Associations Among Microorganisms
Despite an apparent simplicity, bacteria can form complex associations with other organisms. This process is known as symbiosis. These symbiotic associations can be divided into parasitism, mutualism and commensalism. Due to their small size, commensal bacteria are ubiquitous and grow on animals and plants exactly as they would grow on any other surface. However, their growth can be increased by warmth and sweat; in humans, large populations of these organisms are the cause of body odor.
PREDATORS
Some species of bacteria kill and then consume other microorganisms; these species are called predatory bacteria . These include organisms such as Myxococcus xanthus , which forms swarms of cells that kill and digest any bacteria they encounter. Other bacterial predators either attach to their prey in order to digest them and absorb nutrients, such as Vampirococcus , or invade another cell and multiply inside the cytosol, such as Daptobacter .
MUTUALISTS
Certain bacteria form close spatial associations that are essential for their survival. One such mutualistic association, called interspecies hydrogen transfer, occurs between clusters of anaerobic bacteria that consume organic acids, such as butyric acid or propionic acid, and produce hydrogen; and methanogenic Archaea, which consume hydrogen. The bacteria in this association are unable to consume the organic acids since this reaction produces hydrogen, which accumulates in the bacteria’s surroundings. Only the intimate association with the hydrogen-consuming Archaea keeps the hydrogen concentration low enough to allow the bacteria to grow.
In soil, microorganisms that reside in the rhizospehere (a zone that includes the root surface and the soil that adheres to the root after gentle shaking) carry out nitrogen fixation, converting nitrogen gas to nitrogenous compound. This serves to provide an easily absorbable form of nitrogen for many plants that cannot fix nitrogen themselves. Many other bacteria are found as symbionts in humans and other organisms. For example, the presence of over one thousand bacterial species in the normal human gut flora of the intestines can contribute to gut immunity. Synthesis vitamins such as folic acid, vitamin K, and biotin convert sugars to lactic acid (see Lactobacillus ), as well as fermenting complex undigestible carbohydrates. The presence of this gut flora also inhibits the growth of potentially pathogenic bacteria (usually through competitive exclusion), and these beneficial bacteria are consequently sold as probioticdietary supplements.
PATHOGENS
If bacteria form a parasitic association with other organisms, they are classed as pathogens. Pathogenic bacteria are a major cause of human death and disease and cause infections such as tetanus, typhoid fever, diphtheria, syphilis, cholera, foodborne illness, leprosy, and tuberculosis. A pathogenic cause for a known medical disease may only be discovered many years after, as was the case with Helicobacter pylori and peptic ulcer disease. Bacterial diseases are also important in agriculture, with bacteria causing leaf spot, fire blight, and wilts in plants; as well as Johne’s disease, mastitis, salmonella, and anthrax in farm animals.
Each species of pathogen has a characteristic spectrum of interactions with its human hosts. Some organisms, such as Staphylococcus or Streptococcus , can cause skin infections, pneumonia, meningitis and even overwhelming sepsis, a systemic inflammatory response producing shock, massive vasodilation, and death. Yet these organisms are also part of the normal human flora and usually exist on the skin or in the nose without causing any disease at all. Other organisms invariably cause disease in humans, such as the Rickettsia , which are obligate intracellular parasites able to grow and reproduce only within the cells of other organisms. One species of Rickettsia causes typhus, while another causes Rocky Mountain spotted fever. Chlamydia , another phylum of obligate intracellular parasites, contains species that can cause pneumonia, or urinary tract infection and may be involved in coronary heart disease. Finally, some species such as Pseudomonas aeruginosa , Burkholderia cenocepacia , and Mycobacterium avium are opportunistic pathogens and cause disease mainly in people suffering from immunosuppression or cystic fibrosis.
Key Points
- Due to their small size, commensal bacteria are ubiquitous and grow on animals and plants exactly as they would grow on any other surface. Their growth can be increased by warmth and sweat; in humans, large populations of these organisms are the cause of body odor.
- Pathogenic bacteria are a major cause of human death and disease, and cause infections such as tetanus, typhoid fever, diphtheria, syphilis, cholera, foodborne illness, leprosy and tuberculosis.
- Certain bacteria form mutualistic associations, such as close spatial associations that are essential for their survival; for example, interspecies hydrogen transfer.
Key Terms
- mutualism : Any interaction between two species that benefits both; typically involves the exchange of substances or services.
- parasitism : Interaction between two organisms, in which one organism (the parasite) benefits and the other (the host) is harmed.
- commensalism : Describes a relationship between two living organisms where one benefits and the other is not significantly harmed or helped.


36: Getting a Scientific Message Across Means Taking Human Nature into Account (Hendricks)
Rose Hendricks
#reportinginformation, #cognitivebias, #logos, #ethos, #kairos, #pathos, #currentevents, #science
We humans have collectively accumulated a lot of science knowledge. We’ve developed vaccines that can eradicate some of the most devastating diseases. We’ve engineered bridges and cities and the internet. We’ve created massive metal vehicles that rise tens of thousands of feet and then safely set down on the other side of the globe. And this is just the tip of the iceberg (which, by the way, we’ve discovered is melting). While this shared knowledge is impressive, it’s not distributed evenly. Not even close. There are too many important issues that science has reached a consensus on that the public has not .
Scientists and the media need to communicate more science and communicate it better. Good communication ensures that scientific progress benefits society , bolsters democracy , weakens the potency of fake news and misinformation and fulfills researchers’ responsibility to engage with the public. Such beliefs have motivated training programs , workshops and a research agenda from the National Academies of Science, Engineering, and Medicine on learning more about science communication. A resounding question remains for science communicators: What can we do better?
A common intuition is that the main goal of science communication is to present facts; once people encounter those facts, they will think and behave accordingly. The National Academies’ recent report refers to this as the “deficit model.”
But in reality, just knowing facts doesn’t necessarily guarantee that one’s opinions and behaviors will be consistent with them. For example, many people “know” that recycling is beneficial but still throw plastic bottles in the trash. Or they read an online article by a scientist about the necessity of vaccines, but leave comments expressing outrage that doctors are trying to further a pro-vaccine agenda. Convincing people that scientific evidence has merit and should guide behavior may be the greatest science communication challenge, particularly in our “post-truth” era .
Luckily, we know a lot about human psychology – how people perceive, reason and learn about the world – and many lessons from psychology can be applied to science communication endeavors.
Consider human nature
Regardless of your religious affiliation, imagine that you’ve always learned that God created human beings just as we are today. Your parents, teachers and books all told you so. You’ve also noticed throughout your life that science is pretty useful – you especially love heating up a frozen dinner in the microwave while browsing Snapchat on your iPhone.
One day you read that scientists have evidence for human evolution. You feel uncomfortable: Were your parents, teachers and books wrong about where people originally came from? Are these scientists wrong? You experience cognitive dissonance – the uneasiness that results from entertaining two conflicting ideas.
Psychologist Leon Festinger first articulated the theory of cognitive dissonance in 1957, noting that it’s human nature to be uncomfortable with maintaining two conflicting beliefs at the same time. That discomfort leads us to try to reconcile the competing ideas we come across. Regardless of political leaning , we’re hesitant to accept new information that contradicts our existing worldviews.
One way we subconsciously avoid cognitive dissonance is through confirmation bias – a tendency to seek information that confirms what we already believe and discard information that doesn’t.
This human tendency was first exposed by psychologist Peter Wason in the 1960s in a simple logic experiment. He found that people tend to seek confirmatory information and avoid information that would potentially disprove their beliefs.
The concept of confirmation bias scales up to larger issues, too. For example, psychologists John Cook and Stephen Lewandowsky asked people about their beliefs concerning global warming and then gave them information stating that 97 percent of scientists agree that human activity causes climate change. The researchers measured whether the information about the scientific consensus influenced people’s beliefs about global warming.
Those who initially opposed the idea of human-caused global warming became even less accepting after reading about the scientific consensus on the issue. People who had already believed that human actions cause global warming supported their position even more strongly after learning about the scientific consensus. Presenting these participants with factual information ended up further polarizing their views, strengthening everyone’s resolve in their initial positions . It was a case of confirmation bias at work: New information consistent with prior beliefs strengthened those beliefs; new information conflicting with existing beliefs led people to discredit the message as a way to hold on to their original position.
Just shouting louder isn’t going to help. Photo by Maritime Union of New Zealand is licensed under CC BY 2.0
Overcoming cognitive biases
How can science communicators share their messages in a way that leads people to change their beliefs and actions about important science issues, given our natural cognitive biases?
The first step is to acknowledge that every audience has preexisting beliefs about the world. Expect those beliefs to color the way they receive your message. Anticipate that people will accept information that is consistent with their prior beliefs and discredit information that is not.
Then, focus on framing . No message can contain all the information available on a topic, so any communication will emphasize some aspects while downplaying others. While it’s unhelpful to cherry-pick and present only evidence in your favor – which can backfire anyway – it is helpful to focus on what an audience cares about.
For example, these University of California researchers point out that the idea of climate change causing rising sea levels may not alarm an inland farmer dealing with drought as much as it does someone living on the coast. Referring to the impact our actions today may have for our grandchildren might be more compelling to those who actually have grandchildren than to those who don’t. By anticipating what an audience believes and what’s important to them, communicators can choose more effective frames for their messages – focusing on the most compelling aspects of the issue for their audience and presenting it in a way the audience can identify with.
In addition to the ideas expressed in a frame, the specific words used matter. Psychologists Amos Tversky and Daniel Kahneman first showed when numerical information is presented in different ways, people think about it differently. Here’s an example from their 1981 study:
Imagine that the U.S. is preparing for the outbreak of an unusual Asian disease, which is expected to kill 600 people. Two alternative programs to combat the disease have been proposed. Assume that the exact scientific estimate of the consequences of the programs are as follows: If Program A is adopted, 200 people will be saved. If Program B is adopted, there is ⅓ probability that 600 people will be saved, and ⅔ probability that no people will be saved.
Both programs have an expected value of 200 lives saved. But 72 percent of participants chose Program A. We reason about mathematically equivalent options differently when they’re framed differently: Our intuitions are often not consistent with probabilities and other math concepts.
Metaphors can also act as linguistic frames. Psychologists Paul Thibodeau and Lera Boroditsky found that people who read that crime is a beast proposed different solutions than those who read that crime is a virus – even if they had no memory of reading the metaphor. The metaphors guided people’s reasoning , encouraging them to transfer solutions they’d propose for real beasts (cage them) or viruses (find the source) to dealing with crime (harsher law enforcement or more social programs).
The words we use to package our ideas can drastically influence how people think about those ideas.
What’s next?
We have a lot to learn. Quantitative research on the efficacy of science communication strategies is in its infancy but becoming an increasing priority . As we continue to untangle more about what works and why, it’s important for science communicators to be conscious of the biases they and their audiences bring to their exchanges and the frames they select to share their messages.
____________________
Rose Hendricks is a Ph.D. Candidate in Cognitive Science, University of California San Diego. Her essay was originally published in The Conversation.
Getting a Scientific Message Across Means Taking Human Nature into Account by Rose Hendricks is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License .


7.2: Spano v. NY 360 US 315 (1959)
U.S. Supreme Court
Spano v New York, 360 U.S. 315 (1959)
Spano v New York
No. 582
Argued April 27, 1959
Decided June 22, 1959
360 U.S. 315
After petitioner, a foreign-born young man of 25 with a junior highschool education and no previous criminal record, had been indicted for first-degree murder, he retained counsel and surrendered to police at 7:10 p.m. He was then subjected to persistent and continuous questioning by an assistant prosecutor and numerous police officers for virtually eight hours until he confessed, after he had repeatedly requested, and had been denied, an opportunity to consult his counsel. At his trial in a state court, his confession was admitted in evidence over his objection, and he was convicted and sentenced to death.
Held: On the record in this case, petitioner’s will was overborne by official pressure, fatigue and sympathy falsely aroused, his confession was not voluntary, and its admission in evidence violated the Due Process Clause of the Fourteenth Amendment.
Contributors and Attributions
- Authored by : US Government . Located at : https://supreme.justia.com/cases/federal/us/360/315/ . License : Public Domain: No Known Copyright


12.3: Nutrition and Long-Term Cardiovascular Illnesses
By the end of this section, you should be able to:
- 12.2.1 Discuss the impact of nutrition on cardiovascular illness.
Cardiovascular Diseases
The American Heart Association defines cardiovascular disease as any disease of the heart and blood vessels, many of which are related to atherosclerosis (2017). Although some cardiovascular problems are congenital, meaning the client was born with it, most cardiovascular diseases develop over the lifespan. Cardiovascular diseases that develop over the lifespan are often linked with atherosclerosis (National Heart, Lung and Blood Institute, 2022).
Cardiovascular heart disease indicates a decrease in the amount of blood, and therefore oxygen, available to the heart muscle (American Heart Association, 2017). CVD is often the result of narrowed cardiovascular arteries due to the buildup of cholesterol plaque or atherosclerosis. Lipids —LDL, HDL, and triglycerides —are components of cell membranes; they assist with energy movement and storage, production of hormones, and vitamin absorption. However, having too much LDL or triglycerides or too little HDL negatively impacts the body (Cleveland Clinic, 2022b). For this reason, a heart-healthy diet seeks to control high cholesterol (hyperlipidemia) (American Heart Association, 2020).
When clients have hyperlipidemia, consider what happens in their vascular system over time. As the buildup of cholesterol begins to form plaques, the vascular system becomes constricted or narrowed. This narrowing causes the heart to pump more forcefully to push blood throughout the cardiovascular system, resulting in hypertension and, potentially heart failure, if the cardiac muscle becomes fatigued. Additionally, when the plaque area leading to the cardiovascular arteries supplying blood and oxygen to the heart muscle continues to narrow until it eventually becomes too stenosed for blood to flow through it, a myocardial infarction will occur.
Optimally, individuals will adopt a heart-healthy diet early in life that minimizes hyperlipidemia. This eating style provides the nutrients needed to fuel the body while minimizing foods and food preparation styles that increase cholesterol levels. Heart-healthy diets reduce saturated and trans fat by limiting red meat and whole milk dairy products. Additionally, food is prepared by grilling or baking instead of by frying; healthy oils, such as olive oil, are used, when cooking. Heart-healthy diets focus on fruits, vegetables, poultry, fish—especially fish that contains omega-3 such as salmon (Medical News Today, 2021)—whole grains, and nuts. Sodium intake for clients on a healthy heart diet should be limited to 2300 mg/day (FDA, 2022b; American Heart Association, 2020).
Hypertension
Hypertension, or high blood pressure is when the pressure needed to push blood throughout the body’s circulation is consistently high and reads over 130/80 mm Hg (CDC, 2023a). The formation of plaques can cause constriction or narrowing of the arteries (Figure 12.4). If left untreated, hypertension can increase the risk for cardiovascular diseases. Heart healthy diets are designed to decrease cholesterol levels, decrease blood pressure, and reduce risk for developing congestive heart failure. In addition, hypertensive clients may also follow a low-sodium diet. One of the most effective diets to lower blood pressure is the DASH diet (Mayo Clinic, 2021). In addition to limiting the intake of sodium to 2300 mg/day, the DASH diet also includes foods high in potassium, calcium, and magnesium. The DASH diet encourages limiting saturated fats and sugars (Table 12.8).
| Food Types | Serving Size | Recommended Foods |
|---|---|---|
| Grains | 6–8 servings daily |
1 slice of whole grain bread
1 oz of dry cereal ½ cup of cooked rice or pasta |
| Vegetables | 4–5 servings daily |
1 cup of raw leafy green vegetables
½ cup raw or cooked vegetables ½ cup vegetable juice |
| Fruits | 4–5 servings daily |
1 medium fruit
½ cup fresh frozen or canned fruit ½ cup fruit juice |
| Low-fat/no-fat dairy | 2–3 servings daily |
1 cup milk or yogurt
1½ oz cheese |
| Lean meat/poultry/fish | 6 servings daily |
Each serving = 1 oz
Cooked meat, poultry, fish, or egg |
| Fats/oils | 2–3 servings daily |
1 tsp butter substitute or vegetable oil
1 tbsp mayonnaise 2 tbsp salad dressing |
| Nuts, seeds, legumes | 4–5 servings weekly |
⅓ cup nuts
2 tbsp nut butter 2 tbsp seeds |
| Sweets/added sugars | 5 or fewer servings weekly |
1 tbsp sugar, jelly, or jam
1 cup sweetened lemonade or tea |
Holistic Assessment of Cultural Considerations
A holistic assessment of the client extends beyond a physical assessment and a nutritional assessment. The nurse should examine which individual characteristics, aspects of medical history, challenges to maintaining health, interest in wellness promotion and family, community, and cultural aspects impact the client’s ability to develop and adhere to a nutritional plan designed to optimize cardiovascular function. For the cardiovascular client, the nurse should focus attention on providing education to decrease cholesterol levels and hypertension, while providing a nutrient-dense eating plan that fuels the body.
What are the client’s personal characteristics related to food that may impact their ability to adhere to a healthy heart eating plan? For example, the nurse should consider if there are issues related to food enjoyment, food intolerances, and likes and dislikes of certain foods. The nurse can do the following to get a better picture of how to help the client achieve success in developing and adhering to a heart-healthy meal plan:
- Determine if the client likes to engage in the cooking process—plan, prepare, and cook meals—in lieu of eating ready-made processed meals.
- Consider aspects of the client’s overall health history, paying specific attention to cardiovascular-related issues.
- Identify if there are long-term cardiovascular issues or if the issue is an acute exacerbation. If the medical issue is long-term, determine what issues in the past have helped or hindered the client to identify and maintain a heart-healthy diet. Incorporate pertinent family members into this assessment.
The risk for heart disease varies across different ethnic groups. Black women are more likely to have a heart attack , whereas Black men are more likely to die from having a heart attack. Asian people typically have less coronary artery disease than other ethnic groups, although Asian Indian men and Filipino men and women do have a higher risk in comparison to White people. Hispanic women who are young and have a heart attack are at greater risk for dying than young Hispanic men, young Black adults, and young White adults. (Cleveland Clinic, 2023). In the United States, heart disease is the leading cause of death for people in most ethnic groups (CDC, 2023d).
Planning a heart-healthy menu using the cuisines of diverse cultures can improve adherence as well as provide variety. Table 12.9 outlines different cultures and food choices that would be appropriate for heart health.
| Culture | Healthy Food Choices |
|---|---|
| Mexican |
|
|
Asian
(Chinese, Thai, Japanese) |
|
| Indian |
|
| Italian |
|
| Soul food/traditional southern cooking |
|


9.2.2: Kinetics of Spontaneous Decay
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Learning Objectives
- To know how to use half-lives to describe the rates of first-order reactions
Another approach to describing reaction rates is based on the time required for the concentration of a reactant to decrease to one-half its initial value. This period of time is called the half-life of the reaction, written as t 1 /2 . Thus the half-life of a reaction is the time required for the reactant concentration to decrease from [A] 0 to [A] 0/2 . If two reactions have the same order, the faster reaction will have a shorter half-life, and the slower reaction will have a longer half-life.
The half-life of a first-order reaction under a given set of reaction conditions is a constant. This is not true for zeroth- and second-order reactions. The half-life of a first-order reaction is independent of the concentration of the reactants. This becomes evident when we rearrange the integrated rate law for a first-order reaction to produce the following equation:
Substituting [A] 0/2 for [A] and t 1 /2 for t (to indicate a half-life) into Equation \(\ref{21.4.1}\) gives
Substituting \(\ln{2} \approx 0.693\) into the equation results in the expression for the half-life of a first-order reaction:
\[t_{1/2}=\dfrac{0.693}{k} \label{21.4.2}\]
Thus, for a first-order reaction, each successive half-life is the same length of time, as shown in Figure \(\PageIndex{1}\) , and is independent of [A].
If we know the rate constant for a first-order reaction, then we can use half-lives to predict how much time is needed for the reaction to reach a certain percent completion.
| Number of Half-Lives | Percentage of Reactant Remaining | |
|---|---|---|
| 1 | \(\dfrac{100\%}{2}=50\%\) | \(\dfrac{1}{2}(100\%)=50\%\) |
| 2 | \(\dfrac{50\%}{2}=25\%\) | \(\dfrac{1}{2}\left(\dfrac{1}{2}\right)(100\%)=25\%\) |
| 3 | \(\dfrac{25\%}{2}=12.5\%\) | \(\dfrac{1}{2}\left(\dfrac{1}{2}\right )\left (\dfrac{1}{2}\right)(100\%)=12.5\%\) |
| n | \(\dfrac{100\%}{2^n}\) | \(\left(\dfrac{1}{2}\right)^n(100\%)=\left(\dfrac{1}{2}\right)^n\%\) |
As you can see from this table, the amount of reactant left after n half-lives of a first-order reaction is (1/2) n times the initial concentration.
For a first-order reaction, the concentration of the reactant decreases by a constant with each half-life and is independent of [A].
Example \(\PageIndex{1}\)
The anticancer drug cis-platin hydrolyzes in water with a rate constant of 1.5 × 10 −3 min −1 at pH 7.0 and 25°C. Calculate the half-life for the hydrolysis reaction under these conditions. If a freshly prepared solution of cis-platin has a concentration of 0.053 M, what will be the concentration of cis-platin after 5 half-lives? after 10 half-lives? What is the percent completion of the reaction after 5 half-lives? after 10 half-lives?
Given: rate constant, initial concentration, and number of half-lives
Asked for: half-life, final concentrations, and percent completion
Strategy:
- Use Equation \(\ref{21.4.2}\) to calculate the half-life of the reaction.
- Multiply the initial concentration by 1/2 to the power corresponding to the number of half-lives to obtain the remaining concentrations after those half-lives.
- Subtract the remaining concentration from the initial concentration. Then divide by the initial concentration, multiplying the fraction by 100 to obtain the percent completion.
Solution
A We can calculate the half-life of the reaction using Equation \(\ref{21.4.2}\) :
\(t_{1/2}=\dfrac{0.693}{k}=\dfrac{0.693}{1.5\times10^{-3}\textrm{ min}^{-1}}=4.6\times10^2\textrm{ min}\)
Thus it takes almost 8 h for half of the cis-platin to hydrolyze.
B After 5 half-lives (about 38 h), the remaining concentration of cis-platin will be as follows:
After 10 half-lives (77 h), the remaining concentration of cis-platin will be as follows:
C The percent completion after 5 half-lives will be as follows:
The percent completion after 10 half-lives will be as follows:
Thus a first-order chemical reaction is 97% complete after 5 half-lives and 100% complete after 10 half-lives.
Exercise \(\PageIndex{1}\)
Ethyl chloride decomposes to ethylene and HCl in a first-order reaction that has a rate constant of 1.6 × 10 −6 s −1 at 650°C.
- What is the half-life for the reaction under these conditions?
- If a flask that originally contains 0.077 M ethyl chloride is heated at 650°C, what is the concentration of ethyl chloride after 4 half-lives?
- Answer a
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4.3 × 10 5 s = 120 h = 5.0 days;
- Answer b
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4.8 × 10 −3 M
Radioactive Decay Rates
Radioactivity, or radioactive decay, is the emission of a particle or a photon that results from the spontaneous decomposition of the unstable nucleus of an atom. The rate of radioactive decay is an intrinsic property of each radioactive isotope that is independent of the chemical and physical form of the radioactive isotope. The rate is also independent of temperature. In this section, we will describe radioactive decay rates and how half-lives can be used to monitor radioactive decay processes.
In any sample of a given radioactive substance, the number of atoms of the radioactive isotope must decrease with time as their nuclei decay to nuclei of a more stable isotope. Using N to represent the number of atoms of the radioactive isotope, we can define the rate of decay of the sample, which is also called its activity ( A ) as the decrease in the number of the radioisotope’s nuclei per unit time:
Activity is usually measured in disintegrations per second (dps) or disintegrations per minute (dpm).
The activity of a sample is directly proportional to the number of atoms of the radioactive isotope in the sample:
\[A = kN \label{21.4.4}\]
Here, the symbol k is the radioactive decay constant, which has units of inverse time (e.g., s −1 , yr −1 ) and a characteristic value for each radioactive isotope. If we combine Equation \(\ref{21.4.3}\) and Equation \(\ref{21.4.4}\) , we obtain the relationship between the number of decays per unit time and the number of atoms of the isotope in a sample:
Equation \(\ref{21.4.5}\) is the same as the equation for the reaction rate of a first-order reaction, except that it uses numbers of atoms instead of concentrations. In fact, radioactive decay is a first-order process and can be described in terms of either the differential rate law ( Equation \(\ref{21.4.5}\) ) or the integrated rate law:
\[N = N_0e^{−kt} \]
\[\ln \dfrac{N}{N_0}=-kt \label{21.4.6}\]
Because radioactive decay is a first-order process, the time required for half of the nuclei in any sample of a radioactive isotope to decay is a constant, called the half-life of the isotope. The half-life tells us how radioactive an isotope is (the number of decays per unit time); thus it is the most commonly cited property of any radioisotope. For a given number of atoms, isotopes with shorter half-lives decay more rapidly, undergoing a greater number of radioactive decays per unit time than do isotopes with longer half-lives. The half-lives of several isotopes are listed in Table 14.6 , along with some of their applications.
| Radioactive Isotope | Half-Life | Typical Uses |
|---|---|---|
| *The m denotes metastable, where an excited state nucleus decays to the ground state of the same isotope. | ||
| hydrogen-3 (tritium) | 12.32 yr | biochemical tracer |
| carbon-11 | 20.33 min | positron emission tomography (biomedical imaging) |
| carbon-14 | 5.70 × 10 3 yr | dating of artifacts |
| sodium-24 | 14.951 h | cardiovascular system tracer |
| phosphorus-32 | 14.26 days | biochemical tracer |
| potassium-40 | 1.248 × 10 9 yr | dating of rocks |
| iron-59 | 44.495 days | red blood cell lifetime tracer |
| cobalt-60 | 5.2712 yr | radiation therapy for cancer |
| technetium-99 m * | 6.006 h | biomedical imaging |
| iodine-131 | 8.0207 days | thyroid studies tracer |
| radium-226 | 1.600 × 10 3 yr | radiation therapy for cancer |
| uranium-238 | 4.468 × 10 9 yr | dating of rocks and Earth’s crust |
| americium-241 | 432.2 yr | smoke detectors |
Note
Radioactive decay is a first-order process.
Radioisotope Dating Techniques
In our earlier discussion, we used the half-life of a first-order reaction to calculate how long the reaction had been occurring. Because nuclear decay reactions follow first-order kinetics and have a rate constant that is independent of temperature and the chemical or physical environment, we can perform similar calculations using the half-lives of isotopes to estimate the ages of geological and archaeological artifacts. The techniques that have been developed for this application are known as radioisotope dating techniques.
The most common method for measuring the age of ancient objects is carbon-14 dating. The carbon-14 isotope, created continuously in the upper regions of Earth’s atmosphere, reacts with atmospheric oxygen or ozone to form 14 CO 2 . As a result, the CO 2 that plants use as a carbon source for synthesizing organic compounds always includes a certain proportion of 14 CO 2 molecules as well as nonradioactive 12 CO 2 and 13 CO 2 . Any animal that eats a plant ingests a mixture of organic compounds that contains approximately the same proportions of carbon isotopes as those in the atmosphere. When the animal or plant dies, the carbon-14 nuclei in its tissues decay to nitrogen-14 nuclei by a radioactive process known as beta decay, which releases low-energy electrons (β particles) that can be detected and measured:
\[ \ce{^{14}C \rightarrow ^{14}N + \beta^{−}} \label{21.4.7}\]
The half-life for this reaction is 5700 ± 30 yr.
The 14 C/ 12 C ratio in living organisms is 1.3 × 10 −12 , with a decay rate of 15 dpm/g of carbon ( Figure \(\PageIndex{2}\) ). Comparing the disintegrations per minute per gram of carbon from an archaeological sample with those from a recently living sample enables scientists to estimate the age of the artifact, as illustrated in Example 11.Using this method implicitly assumes that the 14 CO 2 / 12 CO 2 ratio in the atmosphere is constant, which is not strictly correct. Other methods, such as tree-ring dating, have been used to calibrate the dates obtained by radiocarbon dating, and all radiocarbon dates reported are now corrected for minor changes in the 14 CO 2 / 12 CO 2 ratio over time.
Example \(\PageIndex{2}\)
In 1990, the remains of an apparently prehistoric man were found in a melting glacier in the Italian Alps. Analysis of the 14 C content of samples of wood from his tools gave a decay rate of 8.0 dpm/g carbon. How long ago did the man die?
Given: isotope and final activity
Asked for: elapsed time
Strategy:
A Use Equation \(\ref{21.4.4}\) to calculate N 0 / N . Then substitute the value for the half-life of 14 C into Equation \(\ref{21.4.2}\) to find the rate constant for the reaction.
B Using the values obtained for N 0 / N and the rate constant, solve Equation \(\ref{21.4.6}\) to obtain the elapsed time.
Solution
We know the initial activity from the isotope’s identity (15 dpm/g), the final activity (8.0 dpm/g), and the half-life, so we can use the integrated rate law for a first-order nuclear reaction ( Equation \(\ref{21.4.6}\) ) to calculate the elapsed time (the amount of time elapsed since the wood for the tools was cut and began to decay).
\\ \dfrac{\ln(N/N_0)}{k}&=t\end{align}\)
A From Equation \(\ref{21.4.4}\) , we know that A = kN . We can therefore use the initial and final activities ( A 0 = 15 dpm and A = 8.0 dpm) to calculate N 0 / N :
Now we need only calculate the rate constant for the reaction from its half-life (5730 yr) using Equation \(\ref{21.4.2}\) :
This equation can be rearranged as follows:
B Substituting into the equation for t ,
From our calculations, the man died 5200 yr ago.
Exercise \(\PageIndex{2}\)
It is believed that humans first arrived in the Western Hemisphere during the last Ice Age, presumably by traveling over an exposed land bridge between Siberia and Alaska. Archaeologists have estimated that this occurred about 11,000 yr ago, but some argue that recent discoveries in several sites in North and South America suggest a much earlier arrival. Analysis of a sample of charcoal from a fire in one such site gave a 14 C decay rate of 0.4 dpm/g of carbon. What is the approximate age of the sample?
- Answer
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30,000 yr
Summary
- The half-life of a first-order reaction is independent of the concentration of the reactants.
- The half-lives of radioactive isotopes can be used to date objects.
The half-life of a reaction is the time required for the reactant concentration to decrease to one-half its initial value. The half-life of a first-order reaction is a constant that is related to the rate constant for the reaction: t 1 /2 = 0.693/ k . Radioactive decay reactions are first-order reactions. The rate of decay, or activity, of a sample of a radioactive substance is the decrease in the number of radioactive nuclei per unit time.