Libros sobre el tema "Distributions de possibilités"

The large-scale energy grid often comprises both AC and DC transmission lines. DC transmission at ultrahigh voltages is more efficient, but consumers need AC at lower voltage so that AC/DC conversion stations are key elements. In modern conversion stations large silicon thyristors are key devices. Energy storage in pumped-hydro installations can be supplemented by compressed air storage. Thermal plants can store energy in molten salts to provide continuous power for consumers. Battery technology is expensive at grid scale but is expanding. The possibility of carbon capture at power plants is discussed. Energy in this chapter is assumed to be electrical energy, with a large portion devoted to the electric grid.

p–n junctions are examined initially and the potential distribution in the junction region is derived based on Poisson’s equation. Next the operation of the transistor is discussed, both in terms of the physics and of equivalent circuits. Potential distributions in metal–semiconductor junctions are derived and the concept of surface states is introduced. The physics of tunnel junctions is discussed in terms of their band structure. The properties of varactor diodes are described and the possibility of parametric amplification is touched upon. Further devices discussed are field effect transistors, charge-coupled devices, controlled rectifiers, and the Gunn effect. The fabrication of microelectronic circuits is discussed, followed by the more recent but related field of micro-electro-mechanical systems. The discipline of nanoelectronics is introduced including the role of carbon nanotubes. Finally, the effect of the development of semiconductor technology upon society is discussed.

This chapter considers returns to the individual from investing in skill. It describes the earnings and employment outcomes of people who have completed different levels of formal education across different countries, and goes on to consider the possible causal mechanisms at work. The methodology for estimating wage returns is critically discussed. Whilst much attention has been devoted to considering ability bias, other issues have received less attention. In particular qualifications or amounts of time spent studying are imperfect proxies for skills produced. Furthermore estimates from wage regressions are almost invariably interpreted through the lens of human capital theory -- the existence of a wage premium indicates that the productivity has increased due to the educational investment. Alternative interpretations are considered. These include the possibility that the premium represents a reward for obtaining a job on a fixed distribution of jobs -- in other words winning a positional competition race. Such possibilities raise several concerns. These include under-utilisation, both of general skills and of skills acquired through work-based training programmes, low marginal returns relative to average returns, and a widening and more risky distribution of payoffs.

The need for any doctor to comprehend, assimilate, analyse, and form an opinion on data cannot be overestimated. This chapter examines the presentation and handling of such data and its subsequent statistical analysis. It covers the organization and description of data, measures of central tendency such as mean, median, and mode, measures of dispersion (standard deviation), and the problems of missing data. Theoretical distributions, such as the Gaussian distribution, are examined and the possibility of data transformation discussed. Inferential statistics are used as a means of comparing groups, and the rationale and use of parametric and non-parametric tests and confidence intervals is outlined. The analysis of categorical variables using the chi-squared test and assessing the value of diagnostic tests using sensitivity, specificity, positive and negative predictive values, and a likelihood ratio are discussed. Measures of association are covered, namely linear regression, as is time-to-event analysis using the Kaplan–Meier method. Finally, the chapter discusses the statistical analysis used when comparing clinical measurements—the Bland and Altman method. Illustrative examples, relevant to the practice of anaesthesia, are used throughout and it is hoped that this will provide the reader with an outline of the methodologies employed and encourage further reading where necessary.

A discussion of the most fundamental of network models, the configuration model, which is a random graph model of a network with a specified degree sequence. Following a definition of the model a number of basic properties are derived, including the probability of an edge, the expected number of multiedges, the excess degree distribution, the friendship paradox, and the clustering coefficient. This is followed by derivations of some more advanced properties including the condition for the existence of a giant component, the size of the giant component, the average size of a small component, and the expected diameter. Generating function methods for network models are also introduced and used to perform some more advanced calculations, such as the calculation of the distribution of the number of second neighbors of a node and the complete distribution of sizes of small components. The chapter ends with a brief discussion of extensions of the configuration model to directed networks, bipartite networks, networks with degree correlations, networks with high clustering, and networks with community structure, among other possibilities.

In the different fields of science, many times, there is a need to estimate the associations between variables, as an approach to understanding the interaction of one as a function of the others. It is usually done by applying restrictive models, such as analysis of variance and linear regression. This type of analysis requires that the dependent variable be continuous, have a normal and constant distribution of the mean and variance. However, when the dependent variable is discrete or categorical, the linear model is not viable. Faced with this impediment, the theory of linear models arises and is expanded to broader categories, which have been called Generalized Linear Models. This category assumes that all distribution functions are exponential, in which the normal distribution is located. In this sense, in this research, Generalized Least Squares methods were applied in their various variants: of moments, ordinary and feasible. These models allow calculating the parameters of models in which the dependent variable has a Poisson or multinomial distribution. In such a way that the Generalized Least Squares serve as a tool to analyze the effect of the elections on public spending and its relationship with the electoral results, analyzing the variables of a budgetary nature, derived from the possibility that the government in power continues or is re-elected. For this, data related to the states and municipalities of México in the period 2007 to 2019 are used.

This chapter identifies a pattern of morphomically distributed root allomorphy—distributed historically, but no longer associated with the perfect aspect of the Latin verb. The allomorphs show a wide variety of phonological forms but they consistently distributed over all and only the tense forms that locally survive from the Latin perfective. The pattern, labelled ‘PYTA’, is repeatedly defended against morphological innovations liable to compromise its integrity, and repeatedly provides the model for a wide range of different morphological innovations. The status of apparent counetrexamples (notably in Aragonese and Aromanian) is explored. The possibility that in Daco-Romance the distributional pattern retains a residual semantic motivation in terms of ‘anteriority’ is examined.

This chapter investigates the equity reasons behind regulations and public finance of healthcare. An inquiry into altruism and redistribution is followed by a discussion of equality and fairness as applied to the distribution of health and healthcare. Voluntary redistribution through cross-subsidized healthcare is explained by paternalistic altruism, that is, most people simply care for their fellow citizens’ access to needed healthcare. The concepts of equity, equality, and fairness in health are explained and defined. Three theories of distributive justice have particular relevance in the context of determining a fair allocation of healthcare: utilitarianism, egalitarianism, and Rawls’ maximin principle. These theories are formally analysed within the framework of a health possibility frontier. The figure illustrates a trade-off between efficiency as health maximization versus equality of health.

Compound word formation is examined from the twin perspectives of comparative grammar and child language acquisition. Points of cross-linguistic variation addressed include the availability of bare-stem endocentric compounding as a “creative” process, head modifier order, the distribution of linking elements in Swedish and German compounds, the possibility of recursion, and the availability of synthetic compounding of the -ER (English dish washer) and bare-stem (French lave-vaisselle) types. Proposals discussed at length include Beard’s Generalization (which links head modifier order in compounds to the position of attributive adjectives), Snyder’s Compounding Parameter (linking syntactic availability of verb-particle constructions and adjectival resultatives to availability of creative endocentric compounding), and Gordon’s acquisitional studies of Kiparsky’s Generalization (concerning restrictions on regular plural-marking within compounds).

The global transition towards sustainable, secure, and affordable electricity supply is driving changes in the consumption, production, and transportation of electricity. This chapter provides an overview of three main causes of political–economic tensions with smart grids in the United States, Europe, and China, namely industry structure, regulatory models, and the impact of energy policy. In all cases, the developments are motivated by the possible improvements in reliability and affordability yielded by smart grids, while sustainability of the electricity sector is not a central motivation. A holistic smart grid vision would open up possibilities for better integration of distributed energy resources. The authors recommend that smart grid investments should remain outside of the regulatory framework for utilities and distribution service operators in order to allow for such developments.

This chapter explores the relationship between hours of work and unemployment. When it comes to time spent working in the United States at present, two problems immediately come to light. First, an asymmetrical distribution of working time persists, with some people overworked and others underemployed. Second, hours are increasingly unstable; precarious on-call work scheduling and gig economy–style employment relationships are the canaries in the coal mine of a labor market that produces fewer and fewer stable jobs. It is possible that some kind of shorter hours movement, especially one that places an emphasis on young workers, has the potential to address these problems. Some policies and processes are already in place to transition into a shorter hours economy right now even if those possibilities are mediated by an anti-worker political administration.

The Choris (750–400 B.C.) and Old Whaling (1150–850 B.C.) cultures are both enigmatic manifestations in the archaeological record in a time of significant cultural “flux” in northwestern Alaskan prehistory. Both cultures represent potential first occurrences in the region—novel lithic assemblage and housing forms (implying the movement of new people into the region) and the possibility of whaling in the case of Old Whaling, and the introduction of pottery and new communal house structures for Choris. However, most of the solid evidence for Choris comes from primarily two locations—Choris Peninsula and Onion Portage, and thus far Old Whaling has only been identified at Cape Krusenstern. The chapter explores both of these archaeological cultures, their chronology and geographic distribution, associated artifacts, subsistence economy, and how they articulate with broader culture history of the western Arctic.

This article focuses on flexible Bayes regression of epidemiologic data involving pregnancy outcomes. It first provides an overview of finite mixture models and nonparametric Bayes methods before discussing some of the possibilities focusing on gestational age at delivery, DDE and age data from the Longnecker et al. (2001) study. More specifically, it examines how risk of premature delivery is impacted by maternal exposure to the pesticide DDT. The results showcase the use of Bayesian analysis in epidemiological studies that collect continuous health outcomes data, and in which the scientific and clinical interest typically focuses on the relationships between exposures and risks of an abnormal response, corresponding to an observation in the tails of the distribution. The article also highlights the limitations of current standard approaches that can be overcome by means of Bayesian analysis using density regression, mixtures and nonparametric models, as developed and applied in this pregnancy outcome study.

This article reviews some of the historic evidence on the evolution of British society, as changes in its structure impacted on the rise of the novel. It considers: (1) Demographic issues, including the size and age composition of the population, factors affecting the mortality rate, the growth in urbanism, and the professions; (2) The economic make-up of society and ways in which the class system operated through the ownership of land and the occupational spread of British people; (3) Issues of gender, as affected by rank, with the limitations and the changing possibilities for women in this era; (4) Writers and readers of the early novel, touching on the growth of literacy, the shifting dynamics of the reading public, the development of the book trade, and the opportunities for professional authors thrown up as patronage declined by new forms of distribution and delivery such as the circulating library.

The functional properties of marine invertebrate larvae represent the sum of the physiological activities of the individual, the interdependence among cells making up the whole, and the correct positioning of cells within the larval body. This chapter examines physiological aspects of nutrient acquisition, digestion, assimilation, and distribution within invertebrate larvae from an organismic and comparative perspective. Growth and development of larvae obviously require the acquisition of “food.” Yet the mechanisms where particulate or dissolved organic materials are converted into biomass and promote development of larvae differ and are variably known among groups. Differences in the physiology of the digestive system (secreted enzymes, gut transit time, and assimilation) within and among feeding larvae suggest the possibility of an underappreciated plasticity of digestive physiology. How the ingestion of seawater by and the existence of a circulatory system within larvae contribute to larval growth and development represent important topics for future research.

Chapter four argues that ignoring a fundamental explanatory question has led interpreters to misunderstand Spinoza’s views on necessity, contingency, possibility, and impossibility. Although the scope of Spinoza’s necessitarianism has also been hotly debated, a central question has gone largely unasked: just what is modality, according to Spinoza? By focusing first on his analysis of necessity, we gain insight into more familiar questions of modal distribution: what exists necessarily, contingently, and so forth. Spinoza ultimately endorses a form of what might now be called anti-essentialism, according to which the modal status of some things depends partly on how those things are conceived. Hence Spinoza affirms both the genuine contingency and strict necessity of one and the same thing’s existence, depending on how it is conceived. After considering Spinoza’s defense of this account, the author turns to why Spinoza thinks we do not, in fact, adopt necessitarian perspectives on the world.

This Report provides a study of the ethnic composition of Myanmar’s subnational units together with an analysis of the historical evolution of the administrative units that existed under the 2008 Constitution. Relying on the 2019 GAD Township reports, the study addresses the limitation of Myanmar’s ethnic data while discussing its use for understanding Myanmar’s complex ethnic make-up. It describes the ethnic distribution of each subnational unit and emphasizes the complex ethnic make-up of Myanmar society—highlighting Myanmar’s ethnic diversity down to the township level. In parallel, the Report analyses the evolution of Myanmar’s administrative boundaries and highlights the possibility of imagining Myanmar’s federal units beyond the status quo. This Report provides democratically legitimate political actors in Myanmar, as well as the international community that supports Myanmar’s federal democracy, with a finer understanding of how Myanmar’s diversity is distributed within each subnational unit.

This innovative book examines the aesthetic event of education. Extending beyond the pedagogy of art or art appreciation, Tyson E. Lewis takes a much broader view of aesthetics and argues that teaching and learning are themselves aesthetic performances. As Jacques Ranciere has recently argued, there is an inherent connection between aesthetics and politics, both of which disrupt conventional distributions of who can speak and think. Here, Lewis extends Ranciere’s general thesis to examine how there is not only an aesthetics of politics but also an aesthetics of education. In particular, Lewis’ analysis focuses on several questions: What are the possibilities and limitations of building analogies between teachers and artists, education and specific aesthetic forms? What is the relationship between democracy and aesthetic sensibilities? Lewis examines these questions by juxtaposing Ranciere’s work on universal teaching, democracy, and aesthetics with Paulo Freire’s work on critical pedagogy, freedom, and literacy. The result is an extension and problematization of Ranciere’s project as well as a new appreciation for the largely ignored aesthetic dimension of Freire’s pedagogy of the oppressed.

In the 1920s, Mexico established rural normales—boarding schools that trained teachers in a new nation-building project. Drawn from campesino ranks and meant to cultivate state allegiance, their graduates would facilitate land distribution, organize civic festivals, and promote hygiene campaigns. In Unintended Lessons of Revolution, Tanalís Padilla traces the history of the rural normales, showing how they became sites of radical politics. As Padilla demonstrates, the popular longings that drove the Mexican Revolution permeated these schools. By the 1930s, ideas about land reform, education for the poor, community leadership, and socialism shaped their institutional logic. Over the coming decades, the tensions between state consolidation and revolutionary justice produced a telling contradiction: the very schools meant to constitute a loyal citizenry became hubs of radicalization against a government that increasingly abandoned its commitment to social justice. Crafting a story of struggle and state repression, Padilla illuminates education's radical possibilities and the nature of political consciousness for youths whose changing identity—from campesinos, to students, to teachers—speaks to Mexico’s twentieth-century transformations.

This bookexplores the democratization of music in our current era made possible by digital technologies. Investigating how the utopian ideals and experimental practices of 20th-century musicians helped to spawn the recent seismic disruptions to the art form, this book explores the current environment of networked connectivity; music has become ubiquitous and increasingly intertwined with everyday life, rendering previous models of creation, performance, dissemination, and consumption largely obsolete. Diffusing Musicidentifies trajectories between 20th-century innovators and the broader redefinition of the musical art in popular culture through technology today. This examination gives context for the advancement of new creative practices and approaches to the art and business of music that are appropriate for current and future technological configurations, and offers new insights on important historical figures and movements. It asserts the prescience and value of experimental music by identifying its powerful influence on the digital milieu in which we all now exist, and presents possibilities for new definitions of musical creativity and distribution as musicking becomes more and more ubiquitous.

World cities are a product of the globalization of economic activity that has characterized post-World War II capitalism, and exhibit characteristics previously found in primate cities but with influence extending far beyond the range of the metropolitan state. They are the culmination of postwar urbanization mechanisms coupled with the rise of transnational corporations that have served to concentrate unprecedented population and economic power/potential. The potential for both human development advantage and disadvantage is historically unprecedented in these new and highly interconnected urban amalgams. In general, human settlement systems are usually understood to include the systemic (regularized) ways in which settlements (hamlets, villages, towns, cities) are linked with one another by trade and other kinds of human interaction. Geographers, historians, and economists have developed models of urban structure and patterning incorporating population location/movement and the location of economic activity to be able to rationally explain and predict urban growth and allocate resources so as to implement equitable distributions. The resulting models served to illustrate the importance of the interactions between specific geographic location, population concentrations, and economic activity. But given the development of world cities, there is the relationship between the size of settlements and political power in intergroup relations to consider. The spatial aspect of population density is, after all, one of the most fundamental variables for understanding the constraints and possibilities of human social organization.

Abstract This book offers a timely and engaging account of how technologies of communication media impact nationalist challenges to global order—shedding new light on how they matter, how they have changed, and how their evolution transforms the conditions of possibility for nationalist order challengers. In the twenty-first century, we have become accustomed to close entanglements between resurgent nationalism and digital media. In Mediatizing the Nation, Ordering the World, Andrew Dougall shows that the relationship between media and nationalist order contestation is far older. Comparing Trump’s breakthrough in the twenty-first-century United States with a similar—but unsuccessful—movement in nineteenth-century Britain, the book argues that communication media shaped these episodes by differently patterning the constitution and distribution of meaning on which they relied. Underpinning this argument is a novel theorization of media in world politics, drawing on insights from media and communications scholarship, in addition to International Relations (IR). Among the book’s key contributions are to explain how media affect vertical challenges to the structure of international orders; to reframe IR’s theoretical engagement with the relationship between media and order; and to situate the internet within a longer history of this relationship, contributing to a more balanced view of its impact.

George Boole (1815–1864), remembered by history as the developer of an eponymous form of algebraic logic, can be considered a pioneer of the information age not only because of the application of Boolean logic to the design of switching circuits but also because of his contributions to the mass distribution of knowledge. In the classroom and the lecture hall, Boole interpreted recent discoveries and debates in a wide range of fields for a general audience. This collection of lectures, many never before published, offers insights into the early thinking of an innovative mathematician and intellectual polymath. Bertrand Russell claimed that “pure mathematics was discovered by Boole,” but before Boole joined a university faculty as professor of mathematics in 1849, advocacy for science and education occupied much of his time. He was deeply committed to the Victorian ideals of social improvement and cooperation, arguing that “the continued exercise of reason” joined all disciplines in a common endeavor. In these talks, Boole discusses the genius of Isaac Newton; ancient mythologies and forms of worship; the possibility of other inhabited planets in the universe; the virtues of free and open access to knowledge; the benefits of leisure; the quality of education; the origin of scientific knowledge; and the fellowship of intellectual culture. The lectures are accompanied by a substantive introduction that supplies biographical and historical context.

As Hollywood shifts towards the digital era, the role of the media franchise has become more prominent. Over a series of essays by a range of international scholars, this edited collection argues that the franchise is now an integral element of American media culture. As such, the collection explores the production, distribution, and marketing of franchises as a historical form of media-making. In particular, the essays analyze the complex industrial practice of managing franchises across interconnected online platforms with a global scope, presenting a network of scholarly texts that critically look at the collision of new and old industrial logics against an ever more fragmented and consolidated mediascape. The authors address how traditional incumbents like film studios and television networks have responded to the rise of big data, Silicon Valley companies like Facebook, Apple, Amazon, Netflix, and Google; the ways in which legacy franchises are adapting to new media platforms and technologies; the significant historical continuities and deviations in franchise-making and how they shape the representation of on-screen texts across digital displays; and, finally, how emerging media formats are expanding the possibility for transmedia experiences. In this regard, The Franchise Era: Managing Media in the Digital Economy offers an in-depth analysis of the tectonic shifts that have disrupted entertainment companies in the twenty-first century, demonstrating that the media franchise stands front and center in this high-stakes environment.

It is increasingly clear that, alongside the spectacular forms of justice activism, the actually existing just city outcomes from different everyday practices of performative politics that produce transformative trajectories and alternative realities in response to particular injustices in situated contexts. The massive diffusion of urban gardening practices (including allotments, community gardens, guerrilla gardening and the multiple, inventive forms of gardening the city) deserve a special attention as experiential learning and in-becoming responses to spatial politics, able to articulate different forms of power and resistance to current state of unequal distribution of benefits and burdens in the urban space. While advancing their socio-environmental claims, urban gardeners makes evident that the physical disposition of living beings and non-living things can both determine and perpetuate injustices or create justice spaces. In so doing, urban gardeners question the inequality-biased structuring and functioning of social formations (most notably urban deprivation, lack of public decision and engagement, and marginalization processes); and conversely create (or allow the creation of) spaces of justice in contemporary cities. This book presents a selection of contributions investigating the possibility and capability of urban gardeners to effectively tackling with spatial injustice; and it offers the readers a sound theoretically-grounded reflections on the topic. Building upon on-the-field experiences in European cities, it presents a wide range of engaged scholarly researches that investigate whether, how and to what extend urban gardening is able to contrast inequalities and disparities in living conditions.

Under Representation argues that the relation between the concepts of universality, freedom and humanity, and the racial order of the modern world is grounded in the founding texts of aesthetic philosophy. It challenges the absence of sustained thought about race in postcolonial studies and the lack of attention to aesthetics in critical race theory. Late Enlightenment discourse on aesthetic experience proposes a decisive account of the conditions of possibility for universal human subjecthood. The aesthetic forges a powerful racial regime of representation whose genealogy runs from enlightenment thinkers like Kant and Schiller to late modernist critics like Adorno and Benjamin. For aesthetic philosophy, representation is an activity that articulates the various spheres of human practice and theory, from the most fundamental acts of perception and reflection to the relation of the subject to the political, the economic, and the social. Representation regulates the distribution of racial identifications along a developmental trajectory: the racialized remain “under representation,” on the threshold of humanity and not yet capable of freedom and civility as aesthetic thought defines those attributes. To ignore the aesthetic is thus to overlook its continuing force in the formation of the racial and political structures down to the present. In its five chapters, Under Representation investigates the aesthetic foundations of modern political subjectivity; race and the sublime; the logic of assimilation and the sterotype; the subaltern critique of representation; and the place of magic and the primitive in modernist concepts of art, aura, and representation.

Employing scientific explanations and hard data, this book shows why coal is such a problem, how the pro-coal forces got to be so powerful, and how those forces might be defeated through political activism. Coal provided the energy to build modern civilization. This energy source raised standards of living, multiplied the earth's population, and enabled people in developed countries to enjoy leisure time. Today, we know that if we burn all the coal available, climate change will continue to increase. But the use of coal isn't purely an environmental issue; there are also political and economic forces at play. This book examines the politics and environmental impact of coal production and distribution, presenting a clear point of view—that we must shift away from coal use—backed by hard data and supplying specific prescriptions for opposing and regulating the coal industry. Author John C. Berg explains how ending the burning of coal (and of oil and natural gas) is a political problem rather than a technical one; explodes the "clean coal" myth, providing scientific documentation of how burning coal emits more greenhouse gases per unit of energy than any other fuel; and describes how controlling coal use in the United States will also serve to restore the possibility of a meaningful international climate agreement. Additionally, readers will understand the critical importance of activism—from local to international—in spurring government regulation to control the coal industry, which can only be defeated politically.

Perhaps the best way to approach the relationship between Deleuze and Agamben is to adopt a method from Deleuze and Guattari’s late philosophy: the conceptual persona.1 Here philosophical proper names do not stand for biographies or persons but for orientations or maps of thinking. Descartes, for example, enables a whole tradition of Cartesian dualism, even for those who neither read nor reference his work. There are some occasions when Agamben’s history of thought also considers proper names less as labels for specific historical individuals, and more as markers of a certain style or distribution of thinking. His recent The Use of Bodies, for example, sees Spinoza as a way of coming to terms with the relation between essence and existence (between what a being is, and that a being is) (UB 160). The names Agamben draws upon are not so much focused upon for their singular greatness, but because they provide a way for thinking about what Agamben sees as the ongoing problem of the singular existence of an individuated being, and then the way that being is identified in language. One might also think of this as the difference between the simple event that something is, and then the identifiable what of the thing. In What is Philosophy? Deleuze and Guattari treat proper names as conceptual personae, suggesting – as Agamben does – that philosophical problems (and the names that attach to them) are not academic exercises of a specific discipline, but have to do with the very possibility of thinking (in domains well beyond philosophy).

The aim of the paper was to determine the influence of root systems of chosen tree species found in the Polish Flysch Carpathians on the increase of soil shear strength (root cohesion) in terms of slope stability. The paper's goal was achieved through comprehensive tests on root systems of eight relatively common in the Polish Flysch Carpathians tree species. The tests that were carried out included field work, laboratory work and analytical calculations. As part of the field work, the root area ratio (A IA) of the roots was determined using the method of profiling the walls of the trench at a distance of about 1.0 m from the tree trunk. The width of the. trenches was about 1.0 m, and their depth depended on the ground conditions and ranged from 0.6 to 1.0 m below the ground level. After preparing the walls of the trench, the profile was divided into vertical layers with a height of 0.1 m, within which root diameters were measured. Roots with diameters from 1 to 10 mm were taken into consideration in root area ratio calculations in accordance with the generally accepted methodology for this type of tests. These measurements were made in Biegnik (silver fir), Ropica Polska (silver birch, black locust) and Szymbark (silver birch, European beech, European hornbeam, silver fir, sycamore maple, Scots pine, European spruce) located near Gorlice (The Low Beskids) in areas with unplanned forest management. In case of each tested tree species the samples of roots were taken, transported to the laboratory and then saturated with water for at least one day. Before testing the samples were obtained from the water and stretched in a. tensile testing machine in order to determine their tensile strength and flexibility. In general, over 2200 root samples were tested. The results of tests on root area ratio of root systems and their tensile strength were used to determine the value of increase in shear strength of the soils, called root cohesion. To this purpose a classic Wu-Waldron calculation model was used as well as two types of bundle models, the so called static model (Fiber Bundle Model — FIRM, FBM2, FBM3) and the deformation model (Root Bundle Model— RBM1, RBM2, mRBM1) that differ in terms of the assumptions concerning the way the tensile force is distributed to the roots as well as the range of parameters taken into account during calculations. The stability analysis of 8 landslides in forest areas of Cicikowicleie and Wignickie Foothills was a form of verification of relevance of the obtained calculation results. The results of tests on root area ratio in the profile showed that, as expected, the number of roots in the soil profile and their ApIA values are very variable. It was shown that the values of the root area ratio of the tested tree species with a diameter 1-10 ram are a maximum of 0.8% close to the surface of the ground and they decrease along with the depth reaching the values at least one order of magnitude lower than close to the surface at the depth 0.5-1.0 m below the ground level. Average values of the root area ratio within the soil profile were from 0.05 to 0.13% adequately for Scots pine and European beech. The measured values of the root area ratio are relatively low in relation to the values of this parameter given in literature, which is probably connected with great cohesiveness of the soils and the fact that there were a lot of rock fragments in the soil, where the tests were carried out. Calculation results of the Gale-Grigal function indicate that a distribution of roots in the soil profile is similar for the tested species, apart from the silver fir from Bie§nik and European hornbeam. Considering the number of roots, their distribution in the soil profile and the root area ratio it appears that — considering slope stability — the root systems of European beech and black locust are the most optimal, which coincides with tests results given in literature. The results of tensile strength tests showed that the roots of the tested tree species have different tensile strength. The roots of European beech and European hornbeam had high tensile strength, whereas the roots of conifers and silver birch in deciduous trees — low. The analysis of test results also showed that the roots of the studied tree species are characterized by high variability of mechanical properties. The values Of shear strength increase are mainly related to the number and size (diameter) of the roots in the soil profile as well as their tensile strength and pullout resistance, although they can also result from the used calculation method (calculation model). The tests showed that the distribution of roots in the soil and their tensile strength are characterized by large variability, which allows the conclusion that using typical geotechnical calculations, which take into consideration the role of root systems is exposed to a high risk of overestimating their influence on the soil reinforcement. hence, while determining or assuming the increase in shear strength of soil reinforced with roots (root cohesion) for design calculations, a conservative (careful) approach that includes the most unfavourable values of this parameter should be used. Tests showed that the values of shear strength increase of the soil reinforced with roots calculated using Wu-Waldron model in extreme cases are three times higher than the values calculated using bundle models. In general, the most conservative calculation results of the shear strength increase were obtained using deformation bundle models: RBM2 (RBMw) or mRBM1. RBM2 model considers the variability of strength characteristics of soils described by Weibull survival function and in most cases gives the lowest values of the shear strength increase, which usually constitute 50% of the values of shear strength increase determined using classic Wu-Waldron model. Whereas the second model (mRBM1.) considers averaged values of roots strength parameters as well as the possibility that two main mechanism of destruction of a root bundle - rupture and pulling out - can occur at the same. time. The values of shear strength increase calculated using this model were the lowest in case of beech and hornbeam roots, which had high tensile strength. It indicates that in the surface part of the profile (down to 0.2 m below the ground level), primarily in case of deciduous trees, the main mechanism of failure of the root bundle will be pulling out. However, this model requires the knowledge of a much greater number of geometrical parameters of roots and geotechnical parameters of soil, and additionally it is very sensitive to input data. Therefore, it seems practical to use the RBM2 model to assess the influence of roots on the soil shear strength increase, and in order to obtain safe results of calculations in the surface part of the profile, the Weibull shape coefficient equal to 1.0 can be assumed. On the other hand, the Wu-Waldron model can be used for the initial assessment of the shear strength increase of soil reinforced with roots in the situation, where the deformation properties of the root system and its interaction with the soil are not considered, although the values of the shear strength increase calculated using this model should be corrected and reduced by half. Test results indicate that in terms of slope stability the root systems of beech and hornbeam have the most favourable properties - their maximum effect of soil reinforcement in the profile to the depth of 0.5 m does not usually exceed 30 kPa, and to the depth of 1 m - 20 kPa. The root systems of conifers have the least impact on the slope reinforcement, usually increasing the soil shear strength by less than 5 kPa. These values coincide to a large extent with the range of shear strength increase obtained from the direct shear test as well as results of stability analysis given in literature and carried out as part of this work. The analysis of the literature indicates that the methods of measuring tree's root systems as well as their interpretation are very different, which often limits the possibilities of comparing test results. This indicates the need to systematize this type of tests and for this purpose a root distribution model (RDM) can be used, which can be integrated with any deformation bundle model (RBM). A combination of these two calculation models allows the range of soil reinforcement around trees to be determined and this information might be used in practice, while planning bioengineering procedures in areas exposed to surface mass movements. The functionality of this solution can be increased by considering the dynamics of plant develop¬ment in the calculations. This, however, requires conducting this type of research in order to obtain more data.