Books on the topic 'Three-Body Effects'

This chapter reviews the ecology of the three species of small mustelids introduced into New Zealand: the ferret (Mustela furo), the stoat (M. erminea) and the weasel (M. nivalis), for biological control of rabbits. New Zealand offers a mosaic of environments totally different from those in which the three species evolved, including a diminishing array of endemic fauna especially vulnerable to mammalian predators. Mustelids in New Zealand display significant adaptive flexibility in diet, habitat selection, co-existence, dispersal, body size, population biology and predatory impact, with results contrasting with those observable in their northern-hemisphere ancestors. These evolutionary and ecological responses by mustelids to new opportunities are of considerable interest to evolutionary ecologists, especially those interested in competition and predator-prey relationships. Likewise, the need to protect New Zealand’s native fauna has stimulated extensive research on alternative options for mitigating the effects of invasive predators, applicable to pest management problems in other countries.

Phenylketonuria is an autosomal recessive biochemical disorder most often resulting from a deficiency of phenylalanine hydroxylase, the enzyme which catalyzes the conversion of phenylalanine to tyrosine. The remainder of the cases are caused by abnormalities in the phenylalanine hydroxylase cofactor, tetrahydrobiopterin. Phenylketonuria can be divided into three subgroups based on the elevation of plasma phenylalanine in the untreated state: “classical,” “variant,” and “benign.” Untreated individuals with classical phenylketonuria develop neurocognitive abnormalities including seizures, microcephaly, and severe intellectual disability. Other clinical effects include a musty body odor, eczema, and reduced skin pigmentation. Treatment, which includes dietary restriction of phenylalanine, supplementation with synthetic protein, and, in some cases, administration of a synthetic form of tetrahydrobiopterin, is successful in preventing the long-term consequences of phenylketonuria.

Routine assessment of nutritional status should be part of normal practice when seeing any patient. The purpose is to document objective nutritional parameters (e.g. anthropometry), identify nutritional deficiencies, and establish nutritional needs. Protein–energy malnutrition has many adverse consequences including growth failure (identified by reference to standard growth charts). Worldwide, malnutrition contributes to a third of deaths in children under 5 years of age, and one in nine people don’t have enough food to lead an active and healthy life. In developed countries, malnutrition complicates both acute and chronic illness with negative effects on outcomes. In clinical practice, a useful approach to nutritional assessment is to consider three elements: ‘what you are’ (i.e. body habitus—underweight for height; short for age; etc.), ‘what you can do’ (functional activity), and ‘what you eat’ (current nutritional intake).

This book argues that depression-era authors contributed to the development of modern environmental thought in three distinct ways. First, they began recognizing as never before the devastating and even apocalyptic effects that humans can have on the environment, particularly in response to the period’s dust storms, flooding, and other human-created ecological disasters. Next, they acknowledged the ecological importance of nonhuman nature, including animal “predators” and “pests,” as conservationists were beginning to do during the period. And lastly, they laid the groundwork for what we now refer to as “environmental justice” by directly connecting environmental exploitation with racial, economic, and gender inequality. To illustrate the reach of environmental thought during the period, the first three chapters of the book focus on different geographical landscapes, including the wilderness, rural, and urban. The last chapter examines the period’s growing concern over the effects of technology on the human and nonhuman world. Ultimately, The Green Depression illustrates the importance of depression-era literature to the development of the modern environmentalist and environmental justice movements. It also contributes to a growing body of scholarship that identifies the importance of environmental thought to the literature and culture of African Americans and other minority groups as well as in considering urban landscapes and other built environments. Finally, the book seeks to initiate a conversation to consider how experiences and ideas from the period have influenced and can inform responses to the intersections of environmental, social, and economic issues in our own time.

Drawing on insights from relevance theory, the chapter explores how W.B. Yeats’s late poem ‘Long-legged Fly’ creates an exemplary occasion for reflecting first on cognition and then on the ways in which cognition might be made manifest in poetic language; in particular, here, in a dominant simile that repeats as a refrain through the poem. Processing the three stanzas’ different inferential, sensorimotor, and intertextual effects, we as readers at one and the same time contemplate in each case a body in thought, and we contemplate ourselves thinking. The poem in this sense repeatedly performs how a history-changing reflective moment holds a range of creative energies in dynamic tension. Relevance theory’s ‘loose’ sifting of literal and other meanings, in Deirdre Wilson’s words, allows us to become aware of these two processes unfolding at the same time, and in relation to each other, as is demonstrated in this close reading.

William James's 1884 theory of emotion is perhaps the most well known of all his psychological ideas, particularly as it forms a key historical landmark in the history of the concept. His notion of “religious emotion” is perhaps one of the most important in shaping the subject in the twentieth century. The complex history of James's theory of emotion begins when he and the Danish physician Karl Georg Lange established a post-Darwinian, organic theory of emotions, in what became known as the James-Lange theory. This view of emotion went against the grain of contemporary theories of emotion in the new psychology, particularly that put forward by Wilhelm Wundt, who argued for a theory of “apperception”—the process by which a state of mind (the affect or emotion) produces bodily effects. This article examines James's theory of emotion and religious emotion, focusing on his views about mind and body. It also discusses three theories of emotion, namely, organic theory, cognitive theory, and social theory. Finally, it considers pluralism, mystical emotions, metaphysical emotions, and the reflex circuit of emotion.

In the growing body of work on democracy, little attention has been paid to its links with migration. This book focuses on the effects of worker remittances—money sent by migrants back to their home countries—and how these resources shape political action in the Global South. Remittances are not only the largest source of foreign income in most autocratic countries, but also, in contrast to foreign aid or international investment, flow directly to citizens. As a result, they provide resources that make political opposition possible, and they decrease government dependency, undermining the patronage strategies underpinning authoritarianism. The book's authors discuss how international migration produces a decentralized flow of income that generally circumvents governments to reach citizens who act as democratizing agents. Documenting why dictatorships fall and how this process has changed in the last three decades, the authors show that remittances increase the likelihood of protest and reduce electoral support for authoritarian incumbents. Combining global macroanalysis with microdata and case studies of Senegal and Cambodia, the book demonstrates how remittances—and the movement of people from authoritarian nations to higher-income countries—foster democracy and its expansion.

Abstract This project contributes to the fields of lyric poetry and poetics (especially poetic form), aesthetics, and German literature by intervening in debates on the social functions, cognitive and emotional effects, and value of poetry. It builds on and moves beyond previous theories of rhythm to tie meter more particularly to the specificities of poetic language in blending of embodied responses, cultural situations, and linguistic particularities. The project examines the German-language tradition across three centuries, arguing that the interdisciplinarity and richness of metrical theory and practice emerge in the heterogeneity of poetry and its defenders in their specific historical moments. Focusing on Friedrich Gottlieb Klopstock, Friedrich Nietzsche, and Durs Grünbein, the book contextualizes each in the metrical and aesthetic debates of his epoch, showing how questions of meter are linked with overarching poetic goals such as the relationship between form and meaning, the adaptation of the Classical past for German literature, and the ways poetry’s sounds work in the body. It argues that Klopstock’s, Nietzsche’s, and Grünbein’s metrical theory and practice offer valuable insights for thinking about the ways poetry works and why it matters.

This chapter examines how the European Union acquired distinctive constitution-like features. It begins with a discussion of three routes to constitutionalization: the first is through changes in the EU's primary law; the second focuses on ‘in between’ constitutionalization; and the third leads directly to the European Court of Justice and its jurisprudence. The chapter proceeds by discussing two developments that have shaped the EU constitutional order almost since the beginning: the emergence of a body of EU law constituting a set of higher-order legal rules, and the consolidation of the constitutional principle of representative democracy. It explains how the supremacy and direct effect of EU law, as well as the EU court's concern with the protection of fundamental rights, helped transform the EU into a constitutional polity. It also considers how the extension of the legislative, budgetary, and other powers of the European Parliament animated the constitutional principle.

The European Parliament (EP) has grown from a “talking shop” to a fully-fledged legislative body in the European Union (EU)’s bicameral system. This process of communautarization and parliamentarization has generated considerable attention in the academic field. Furthermore, in today’s political environment—characterized by the polarization of public opinion, Brexit, the lingering effects of the Eurozone crisis, and the steady rise of Euroskeptical and radical forces throughout Europe—the role of the European Parliament (EP) is perhaps more critical to understand and assess than ever before. An overarching question in the literature is how “normal” the EP has become. Drawing on David Easton’s political systems approach, we examine this condition in three sub-literatures: the literature on inputs (demands), the literature on withinputs (inter-institutional processing of inputs), and the literature on outputs (EP decisions and actions, and the impact thereof). Building on this literature and contributing to the ongoing debate on the nature and significance of the EP, we propose to conceptualize the EP as “a normal parliament in a polity of a different kind.” This paradoxical conceptualization reflects abundant insights that, despite the EP gaining comprehensive lawmaking powers that are quite unparalleled in the world of international politics, its functioning and significance remain profoundly, distinctly, and probably durably, shaped by the multilevel nature of EU politics.

A commodity chain refers to “a network of labor and production processes whose end result is a finished commodity.” The attention given to this concept has quickly translated into an expanding body of global chains literature. Research into global commodity chains (GCC), and later global value chains (GVC), is an endeavor to explain the social and organizational structure of the global economy and its dynamics by examining the commodity chains of a specific product of service. The GCC approach first emerged in the mid-1980s from world-system research and was reformulated in the early 1990s by development scholars. The development-oriented GCC approach turned the focus of GCC analysis to actor-centered processes in the global economy. One of the initial criticisms facing the GCC approach was its exclusive focus on internal conditions and organizational linkages, lacking systemic attention to the effect of domestic institutions and internal capacity on economic development. Other critics pointed to the narrow scope of GCC research. With the huge expansion in global chains literature in the past decade—not only in volume but also in depth and scope—efforts have been made to elaborate the global chains framework and to render it industry neutral, as partly reflected in the adoption of the term “global value chains.” Three key research themes surround these recent evolutions of global chains literature: GVC governance, “upgrading,” and the social construction of global value chains. Existing literature, however, still has theoretical and methodological gaps to redress.

Children take their first steps, produce their first words, and become able to solve many new problems seemingly overnight. Yet, each change reflects many other previous developments that occurred in the whole child across a range of domains, and each change, in turn, will provide opportunities for future development. This book proposes that all change can be explained in terms of developmental cascades such that events that occur at one point in development set the stage, or cause a ripple effect, for the emergence or development of different abilities, functions, or behaviors at another point in time. The authors argue that these developmental cascades are influenced by different kinds of constraints that do not have a single foundation: They may originate from the structure of the child’s nervous system and body, the physical or social environment, or knowledge and experience. These constraints occur at multiple levels of processing and change over time, and both contribute to developmental cascades and are the product of them. The book presents an overview of this developmental cascade perspective as a general framework for understanding change throughout the lifespan, although it is applied primarily to cognitive development in infancy. The book also addresses how a cascade approach obviates the dichotomy between domain-general and domain-specific mechanisms. The framework is applied in detail to three domains within infant cognitive development—namely, looking behavior, object representations, and concepts for animacy—as well as two domains unrelated to infant cognition (gender and attachment).

Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.

Armed conflict is ultimately about the violent confrontation between two or more groups; however, there is a range of behaviors, both violent and nonviolent, pursued by governments and rebel groups while conflict is ongoing that impacts the course and outcomes of that violence. The use of judicial or quasi-judicial institutions during armed conflict is one such behavior. While there is a well-developed body of literature that examines the conditions under which governments engage with the legacies of violence following armed conflict, we know comparatively little about these same institutions used while conflict is ongoing.Similar to the use of transitional justice following armed conflict or post-conflict justice, during-conflict transitional justice (DCJ) refers to “a judicial or quasi-judicial process initiated during an armed conflict that attempts to address wrongdoings that have taken or are taking place as part of that conflict” (according to Loyle and Binningsbø). DCJ includes a variety of institutional forms pursued by both governments and rebel groups such as human rights trials, truth commissions or commissions of inquiry, amnesty offers, reparations, purges, or exiles.As our current understanding of transitional justice has focused exclusively on these processes following a political transition or the termination of an armed conflict, we have a limited understanding of how and why these processes are used during conflict. Extant work has assumed, either implicitly or explicitly, that transitional justice is offered and put in place once violence has ended, but this is not the case. New data on this topic from the During-Conflict Justice dataset by Loyle and Binningsbø suggests that the use of transitional justice during conflict is a widespread and systematic policy across multiple actor groups. In 2017, Loyle and Binningsbø found that DCJ processes were used during over 60% of armed conflicts from 1946 through 2011; and of these processes 10% were put in place by rebel groups (i.e., the group challenging the government rather than the government in power).Three main questions arise from this new finding: Under what conditions are justice processes implemented during conflict, why are these processes put in place, and what is the likely effect of their implementation on the conflict itself? Answering these questions has important implications for understanding patterns of government and rebel behavior while conflict is ongoing and the impacts of those behaviors. Furthermore, this work helps us to broaden our understanding of the use of judicial and quasi-judicial processes to those periods where no power shift has taken place.

It is obvious that the process of developing cancer—oncogenesis—is a multistep process. We know that smoking, obesity, and a family history are strong independent predictors of developing malignancy; yet, in clinics, we often see that some heavy smokers live into their nineties and that some people with close relatives affected by cancer spend many years worrying about a disease that, in the end, they never contract. For many centuries scientists have struggled to understand the process that make cancer cells different from normal cells. There were those in ancient times who believed that tumours were attributable to acts of the gods. Hippocrates suggested that cancer resulted from an imbalance between the black humour that came from the spleen, and the other three humours: blood, phlegm, and bile. It is only in the last 100 years that biologists have been able to characterize some of the pathways that lead to the uncontrolled replication seen in cancer, and subsequently examine exactly how these pathways evolve. The rampant nature by which cancer invades local and distant tissues, as well its apparent ability to spread between related individuals led some, such as Peyton Rous in 1910, to suggest that cancer was an infectious condition. He was awarded a Nobel Prize in 1966 for the 50 years of work into investigating a link between sarcoma in chickens and a retrovirus that became known as Rous sarcoma virus. He had shown how retroviruses are able to integrate sequences of DNA coding for errors in cellular replication control (oncogenes) by introducing into the human cell viral RNA together with a reverse transcriptase. Viruses are now implicated in many cancers, and in countries where viruses such as HIV and EBV are endemic, the high incidence of malignancies such as Kaposi’s sarcoma and Burkitt’s lymphoma is likely to be directly related. There are several families of viruses associated with cancer, broadly classed into DNA viruses, which mutate human genes using their own DNA, and retroviruses, like Rous sarcoma virus, which insert viral RNA into the cell, where it is then transcribed into genes. This link with viruses has not only led to an understanding that cancer originates from genetic mutations, but has also become a key focus in the design of new anticancer therapies. Traditional chemotherapies either alter DNA structure (as with cisplatin) or inhibit production of its component parts (as with 5-fluorouracil.) These broad-spectrum agents have many and varied side effects, largely due to their non-specific activity on replicating DNA throughout the body, not just in tumour cells. New vaccine therapies utilizing gene-coding viruses aim to restore deficient biological pathways or inhibit mutated ones specific to tumour cells. The hope is that these gene therapies will be effective and easily tolerated by patients, but development is currently progressing with caution. In a trial in France of ten children suffering from X-linked severe combined immunodeficiency and who were injected with a vector that coded for the gene product they lacked, two of the children subsequently died from leukaemia. Further analysis confirmed that the DNA from the viral vector had become integrated into an existing, but normally inactive, proto-oncogene, LM02, triggering its conversion into an active oncogene, and the development of life-threatening malignancy. To understand how a tiny change in genetic structure could lead to such tragic consequences, we need to understand the molecular biology of the cell and, in particular, to pay attention to the pathways of growth regulation that are necessary in all mammalian cell populations. Errors in six key regulatory pathways are known as the ‘hallmarks of cancer’ and will be discussed in the rest of this chapter.