Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 089335130X ISBN 13: 9780893351304
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 85,55
Quantità: 2 disponibili
Aggiungi al carrelloTaschenbuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -There are almost as many explanations for psychiatric disorders as there are patients with them. Each explanation is intriguing, some of them are systematic, all of them have intellectually powerful champions. Yet their very multitude is a scandal. It provokes the professionally debilitating challenge: Why does every psychiatric explanation satisfy some people and not others Recently this question has received a simple answer. We cannot satisfactorily explain that which we lack the skill to describe. To develop the fundamental skill a student must see many patients under the direction of an experienced and involved instructor to whom he can show his results, accept correction and advance in his abilities. But we need a means to amplify the clinical experience, a text to supplement the instructor in bringing forth and strengthening the vocabulary needed to describe the phenomenology, presentations and distinctions amongst psychiatric patients. A 'programmed text' such as this one is a satisfactory means because it can cover rapidly many themes and variations of a vast clinical experi ence. It can permit the reader to progress at his own speed but bring a sense of mastery to him as he progresses. He can check his knowledge as he sees patients on the clinical services. This kind of text combined with patient practice is thorough, fast and fun, but should succeed in the important task of rapidly building for the student an authentic set of terms and concepts suitable for both clinical work and research. 532 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 0852005806 ISBN 13: 9780852005804
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 85,55
Quantità: 2 disponibili
Aggiungi al carrelloTaschenbuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -2. The Psychiatric Examination 7 3. Organic Brain Syndromes-Delirium and Dementia 21 4. Psychosis 37 5. Non-psychotic Disturbances 47 6. The Violent Patient 59 7. The Suicidal Patient 67 8. Alcohol Abuse 75 9. Drug Abuse 85 10. Other Common Psychiatric Emergencies 101 Appendix: Psychiatric Side Effects of Medical Drugs 109 Index 165 Chapter 1 Introduction INTRODUCTION Psychiatric patients can be among the most disconcerting patients to treat in an emergency department setting. Because these patients often present with violence, confusion, suicidal attempts and bizarre behavior and thoughts, non-psychiatric physicians often react with various degrees of discomfort and avoidance. However, it is often important to make a decision whether the presenting symptoms are due to functional or organic illness since serious morbidity and mortality can occur in patients with acute organic brain disease. The differential diagnosis would include: Functional (Psychiatric) Disease Organic Disease Affective Disorders Delirium Schizophrenic Disorders Dementia Personality Disorders Anxiety Disorders Adjustment Disorders Findings which are helpful in raising the index of suspicion for organic disease are: a) Disorientation to time and place b) Fluctuating level of consciousness 1 EMERGENCY PSYCHIATRY/2 c) Age over 45 with no previous psychiatric history d) Abnormal autonomic signs (vital signs, pupillary responses, sweating) e) Acute onset of psychotic illness (hours to days) f) Ongoing medical disease and its treatment g) Recognition that hallucinations and delusions are frequently observed in organic as well as functional disease. 180 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 9027713022 ISBN 13: 9789027713025
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 85,55
Quantità: 2 disponibili
Aggiungi al carrelloTaschenbuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -x I wish to express my thanks to all contributors to this volume for their collaboration, and especially to Professor laakko Hintikka, Editor of Synthese Library, for his help in editing this book. THE EDITOR INTRODUCTION TO THE SECOND IMPRESSION The articles included in this collection represent what may be called the standard modal approach to deontic logic (the logic of normative concepts), in which deontic logic is treated as a branch of modal logic, and the normative concepts of obligation, permission (permissibility) and prohibi tion are regarded as analogous to the 'alethic' modalities necessity, possi bility and impossibility. In his recent paper [16] Simo Knuuttila has shown that this approach can be traced back to late medieval philosophy. Several 14th century philosophers observed the analogies between deontic and alethic modalities and 4iscussed the deontic interpretations of various laws of modal logic. A relatively simple deontic system of this kind (called the system D or K D; cf. Lemmon and Scott [17], pp. 50-51, Chellas [10], p. 131) is obtained by adding to propositional logic two deontic axioms (or axiom schemata), (K) O(A :::J B) :::J (OA :::J OB) and (D) OA :::J ~ 0 ~ A, where '0' is the obligation operator, and the deontic variant of the 'rule of necessitation' (0) From A, to infer ~A. 204 pp. Englisch.
Lingua: Inglese
Editore: Springer, Springer Netherlands Jul 1981, 1981
ISBN 10: 9024725119 ISBN 13: 9789024725113
Da: buchversandmimpf2000, Emtmannsberg, BAYE, Germania
EUR 53,49
Quantità: 1 disponibili
Aggiungi al carrelloTaschenbuch. Condizione: Neu. This item is printed on demand - Print on Demand Titel. Neuware -The European Community Energy R & D Programmes.- Energy Conservation.- Energy Savings in Buildings.- Use of Heat Pumps.- Urban Transport.- Recovery of Residual Heat.- Recycling of Materials.- Production of Energy from Waste.- Industrial Processes.- Development of Methods of Accumulating Secondary Energy.- Second Programme.- Production and Use of Hydrogen.- Thermochemical Production of Hydrogen.- Electrolytic Production of Hydrogen.- Hydrogen Use, Storage and Transportation.- Second Programme.- Solar Energy.- Solar Energy Applications to Dwellings.- Thermomechanical Solar Power Plants.- Photovoltaic Power Generation.- Photoelectrochemical, Photochemical and Photobiological Processes.- Energy from Biomass.- Solar Radiation Data.- Second Programme.- Geothermal Energy.- Acquisition and Collection of Existing and New Geothermal Data.- Prospecting Methodology.- Utilisation of Hot Water Sources (Low Enthalpy).- Utilisation of Steam Sources (High Enthalpy).- Hot Dry Rocks.- Second Programme.- Energy Systems Analysis and Strategy Studies.- First Programme.- Second Programme.- Conclusions.- Appendix 1 ¿ Conferences and Publications arising out of the First Energy R & D Programme.Springer-Verlag KG, Sachsenplatz 4-6, 1201 Wien 52 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 9027712352 ISBN 13: 9789027712356
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 96,29
Quantità: 2 disponibili
Aggiungi al carrelloTaschenbuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -Anthropological approaches to the sciences have developed as part of a broader tradition concerned about the place of the sciences in today's world and in some basic sense concerned with questions about the legitimacy of the sciences. In the years since the second World War, we have seen the emergence of a number of different attempts both to analyze and to cope with the successes of the sciences, their broad penetration into social life, and the sense of problem and crisis that they have projected. Among the of movements concerned about the earlier responses were the development social responsibility of scientists and technological practitioners. There is little doubt that this was a direct outgrowth of the role of science in the war epitomized by the successful construction and catastrophic use of the atomic bomb. The recognition of the deep social utility of science, and especially its role as an instrument of war, fostered curiosity about the earlier develop ment of scientific disciplines and institutional forms. The history of science as an explicit diSCipline with full-time practitioners can be seen as an attempt to locate science in temporal space - first in its intellectual form and second ly in its institutional or social form. The sociology of science, while certainly having roots in the pre-war work of Robert K. 296 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 9027713243 ISBN 13: 9789027713247
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 106,99
Quantità: 2 disponibili
Aggiungi al carrelloTaschenbuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -The bulk of known results in spectral and scattering theory for Schrodinger operators has been derived by time-independent (also called stationary) methods, which make extensive use of re solvent estimates and the spectral theorem. In very recent years there has been a partial shift of emphasis from the time-indepen dent to the time-dependent theory, due to the discovery of new, essentially time-dependent proofs of a fair number of the principal results such as asymptotic completeness, absence of singularly con tinuous spectrum and properties of scattering cross sections. These new time-dependent arguments are somewhat simpler than the station ary ones and at the same time considerably closer to physical in tuition, in that they are based on a rather detailed description of the time evolution of states in configUration space (whence the designation 'geometric methods' used by some authors). It seemed interesting to me to present some of these new meth ods from a strictly time-dependent point of view, by considering as the basic mathematical object strongly continuous unitary one parameter groups and avoiding the spectral theorem completely. The present volume may be viewed as an essay in this spirit. It is an extended version of a course taught in 1979 at the University of Geneva to undergraduate students enrolled in mathematical physics. 248 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands, Springer Netherlands Jul 1981, 1981
ISBN 10: 9024724570 ISBN 13: 9789024724574
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 160,49
Quantità: 2 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -C. S. Peirce's indictment that 'the chief cause of [metaphysics'] backward condition is that its leading professors have been theo (Collected Papers 6:3) falls heavily at my door. For it logians' was out of reflection upon religious experience and its meaning that the present relational metaphysic was conceived. My hope, however, is that its scope is sufficiently wider than its theological origins to justify its appearance as a work in philosophy. Having been nurtured in existential philosophy and having reached some measure of maturity with the wise counsel of Professor Dr. Fritz Buri, of Basel, I came to feel that theology as a modern discipline had reached an impasse owing to its overextended commitments to a subject-object paradigm of thought. Even those theologians who despaired of these ties seemed unable to find an independent alternative idiom for their ideas. A second tension in my thinking resulted from the inordinate neglect by theologians of the natural world. Also, my natural interest in physical understanding seemed unfulfilled within the narrow confines of theology, even of philosophical theology as then practiced. As I turned decisively toward the study of modern physics, and especially of cosmology, a new world seemed to open up to me. After extensive study with prominent astronomers and physicists, it began to dawn on me that the new physics has devised conceptual paradigms of thought which could be generalized into a metaphysical system of universal interest. 248 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 9061930979 ISBN 13: 9789061930976
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 160,49
Quantità: 2 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -Scotland is fortunate in being very richly endowed with natural fresh waters in the form of numerous lochs and rivers. These constitute on the one hand an attractive feature of the landscape and on the other a major resource for industry and recreation. Thus there are about 3800 lochs over4 ha in area and these form approximately 1.0% of the total surface area of Scotland. Com parable figures for England and Wales are 1700 lakes and 0.05% of the land surface, and in terms of volume. Loch Ness contains more water than all the lakes and reservoirs in England and Wales put together (Smith & Lyle 1979). Many of the Scottish lochs are large and clean and consequently are particularly valuable in resource terms. The decision as to which are actually the largest lochs is debatable, particularly when the main criteria of greatest surface area, length, volume and depth each gives a different water (Lochs Lomond. Awe, Ness and Morar respectively). These four then are certainly among the largest lochs in the country, but close to them in size come several other large waters, among which is Loch Shiel- which is exceeded in length only by Lochs Awe, Ness and Lomond. These five very large lochs (Frontis piece) form the group of waters selected for the comparative studies described in this volume. 312 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 9027712964 ISBN 13: 9789027712967
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 160,49
Quantità: 2 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -The thermodynamics of the atmosphere is the subject of severai chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fiII this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can play a role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the urst four chapters), they are only briefly discussed, and emphasis is laid on those topics that wilI be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics ofirreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a rigorous formulation of the thermodynamic functions of c10uds (exclusive of any consideration of microphysical effects) and a better understanding of the approx imations usually implicit in practical applications. 280 pp. Englisch.
Lingua: Inglese
Editore: Springer, Springer Netherlands Jul 1981, 1981
ISBN 10: 9061930979 ISBN 13: 9789061930976
Da: buchversandmimpf2000, Emtmannsberg, BAYE, Germania
EUR 160,49
Quantità: 1 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - Print on Demand Titel. Neuware -Scotland is fortunate in being very richly endowed with natural fresh waters in the form of numerous lochs and rivers. These constitute on the one hand an attractive feature of the landscape and on the other a major resource for industry and recreation. Thus there are about 3800 lochs over4 ha in area and these form approximately 1.0% of the total surface area of Scotland. Com parable figures for England and Wales are 1700 lakes and 0.05% of the land surface, and in terms of volume. Loch Ness contains more water than all the lakes and reservoirs in England and Wales put together (Smith & Lyle 1979). Many of the Scottish lochs are large and clean and consequently are particularly valuable in resource terms. The decision as to which are actually the largest lochs is debatable, particularly when the main criteria of greatest surface area, length, volume and depth each gives a different water (Lochs Lomond. Awe, Ness and Morar respectively). These four then are certainly among the largest lochs in the country, but close to them in size come several other large waters, among which is Loch Shiel- which is exceeded in length only by Lochs Awe, Ness and Lomond. These five very large lochs (Frontis piece) form the group of waters selected for the comparative studies described in this volume.Springer-Verlag KG, Sachsenplatz 4-6, 1201 Wien 312 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands, Springer Netherlands Jul 1981, 1981
ISBN 10: 9024724570 ISBN 13: 9789024724574
Da: buchversandmimpf2000, Emtmannsberg, BAYE, Germania
EUR 160,49
Quantità: 1 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - Print on Demand Titel. Neuware -C. S. Peirce's indictment that 'the chief cause of [metaphysics'] backward condition is that its leading professors have been theo (Collected Papers 6:3) falls heavily at my door. For it logians' was out of reflection upon religious experience and its meaning that the present relational metaphysic was conceived. My hope, however, is that its scope is sufficiently wider than its theological origins to justify its appearance as a work in philosophy. Having been nurtured in existential philosophy and having reached some measure of maturity with the wise counsel of Professor Dr. Fritz Buri, of Basel, I came to feel that theology as a modern discipline had reached an impasse owing to its overextended commitments to a subject-object paradigm of thought. Even those theologians who despaired of these ties seemed unable to find an independent alternative idiom for their ideas. A second tension in my thinking resulted from the inordinate neglect by theologians of the natural world. Also, my natural interest in physical understanding seemed unfulfilled within the narrow confines of theology, even of philosophical theology as then practiced. As I turned decisively toward the study of modern physics, and especially of cosmology, a new world seemed to open up to me. After extensive study with prominent astronomers and physicists, it began to dawn on me that the new physics has devised conceptual paradigms of thought which could be generalized into a metaphysical system of universal interest.Springer-Verlag GmbH, Tiergartenstr. 17, 69121 Heidelberg 248 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 9028627219 ISBN 13: 9789028627215
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 208,64
Quantità: 2 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -Proceedings of the NATO Advanced Study Institute, Bonas, France, July 6-19, 1980 456 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 902771133X ISBN 13: 9789027711335
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 213,99
Quantità: 2 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware 402 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 9027712921 ISBN 13: 9789027712929
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 213,99
Quantità: 2 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -The IAU Colloquium No. 59, 'The effects of mass loss on Stellar Evolution' was held on September 15-19, 1980 at the International Centre for Theoretical Physics, Miramare, Trieste (Italy), under the auspices of the IAU Executive Co~ mittee and the Italian National Council of Research. The planning of this conference began two years ago du ring the IAU Symposium No. 83 'Mass loss and evolution of 0 type stars' (Qualicum Beach, Victoria, Canada) when we felt that mass loss and its effects on the evolution of stars was too broad a subject for being confined to 0 type stars only. Therefore we thought that a conference dealing with the general problem of mass loss across the whole HR diagram would have been of interest to all people working in the field. The main idea was that bringing together Astronomers and Astrophysicists of the widest range of interests and e~ pertize - all in some way related to the problem of mass loss from stars - would have spurred thorough discussions on the many aspects and implications of this topic. We hope this goal has been achieved. Furthermore, the most recent observational and theoreti cal developments on the problem of mass loss from early ty pe stars avoided this meeting to be a simple updating of the Qualicum Beach Symposium as far as this issue is concerned. 592 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 9027712972 ISBN 13: 9789027712974
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 246,10
Quantità: 2 disponibili
Aggiungi al carrelloTaschenbuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -The thermodynamics of the atmosphere is the subject of severai chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fiII this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can play a role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the urst four chapters), they are only briefly discussed, and emphasis is laid on those topics that wilI be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics ofirreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a rigorous formulation of the thermodynamic functions of c10uds (exclusive of any consideration of microphysical effects) and a better understanding of the approx imations usually implicit in practical applications. 280 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands, Springer Netherlands Jul 1981, 1981
ISBN 10: 9028627219 ISBN 13: 9789028627215
Da: buchversandmimpf2000, Emtmannsberg, BAYE, Germania
EUR 213,99
Quantità: 1 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - Print on Demand Titel. Neuware -Proceedings of the NATO Advanced Study Institute, Bonas, France, July 6-19, 1980Springer Verlag GmbH, Tiergartenstr. 17, 69121 Heidelberg 456 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands, Springer Netherlands Jul 1981, 1981
ISBN 10: 902771133X ISBN 13: 9789027711335
Da: buchversandmimpf2000, Emtmannsberg, BAYE, Germania
EUR 213,99
Quantità: 1 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - Print on Demand Titel. Neuware Springer Verlag GmbH, Tiergartenstr. 17, 69121 Heidelberg 402 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands, Springer Netherlands Jul 1981, 1981
ISBN 10: 9024721237 ISBN 13: 9789024721238
Da: buchversandmimpf2000, Emtmannsberg, BAYE, Germania
EUR 213,99
Quantità: 1 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - Print on Demand Titel. Neuware -1. STRUCTURE AND REFERENCES 1.1. The main part of the dictionary consists of alphabetically arranged articles concerned with basic logical theories and some other selected topics. Within each article a set of concepts is defined in their mutual relations. This way of defining concepts in the context of a theory provides better understand ing of ideas than that provided by isolated short defmitions. A disadvantage of this method is that it takes more time to look something up inside an extensive article. To reduce this disadvantage the following measures have been adopted. Each article is divided into numbered sections, the numbers, in boldface type, being addresses to which we refer. Those sections of larger articles which are divided at the first level, i.e. numbered with single numerals, have titles. Main sections are further subdivided, the subsections being numbered by numerals added to the main section number, e.g. I, 1.1, 1.2, . , 1.1.1, 1.1.2, and so on. A comprehensive subject index is supplied together with a glossary. The aim of the latter is to provide, if possible, short defmitions which sometimes may prove sufficient. As to the use of the glossary, see the comment preceding it.Springer Verlag GmbH, Tiergartenstr. 17, 69121 Heidelberg 454 pp. Englisch.
Lingua: Inglese
Editore: Springer Netherlands Jul 1981, 1981
ISBN 10: 9024721237 ISBN 13: 9789024721238
Da: BuchWeltWeit Ludwig Meier e.K., Bergisch Gladbach, Germania
EUR 294,25
Quantità: 2 disponibili
Aggiungi al carrelloBuch. Condizione: Neu. This item is printed on demand - it takes 3-4 days longer - Neuware -1. STRUCTURE AND REFERENCES 1.1. The main part of the dictionary consists of alphabetically arranged articles concerned with basic logical theories and some other selected topics. Within each article a set of concepts is defined in their mutual relations. This way of defining concepts in the context of a theory provides better understand ing of ideas than that provided by isolated short defmitions. A disadvantage of this method is that it takes more time to look something up inside an extensive article. To reduce this disadvantage the following measures have been adopted. Each article is divided into numbered sections, the numbers, in boldface type, being addresses to which we refer. Those sections of larger articles which are divided at the first level, i.e. numbered with single numerals, have titles. Main sections are further subdivided, the subsections being numbered by numerals added to the main section number, e.g. I, 1.1, 1.2, . , 1.1.1, 1.1.2, and so on. A comprehensive subject index is supplied together with a glossary. The aim of the latter is to provide, if possible, short defmitions which sometimes may prove sufficient. As to the use of the glossary, see the comment preceding it. 454 pp. Englisch.