The Earliest Tool-makers

Antiquity ◽  
1956 ◽  
Vol 30 (117) ◽  
pp. 4-8 ◽  
Author(s):  
Kenneth Oakley
Keyword(s):  
Practical Importance ◽  
Point Of View ◽  
Fossil Remains

Man has been defined in many ways, as the talking animal, the religious animal, and so on, but the most satisfactory definition from the scientific point of view is probably Man the Tool-maker. One might ask, why bother to define man, considering his uniqueness and self-evident characteristics? But from the standpoint of students of evolution, particularly those concerned with the interpretation of fossil remains of early man and his possible ancestors, to define man is of practical importance.

scholarly journals On Kaufmann's theory of the impact of the pianoforte hammer

1920 ◽  
Vol 97 (682) ◽  
pp. 99-110 ◽  
Keyword(s):  
Initial Conditions ◽  
Practical Importance ◽  
Prima Facie ◽  
Point Of View ◽  
Infinite Length ◽  
Modes Of Vibration ◽  
Rigorous Treatment ◽  
The Subject ◽  
Set Up ◽  
The Impact

The theory of the vibrations of the pianoforte string put forward by Kaufmann in a well-known paper has figured prominently in recent discussions on the acoustics of this instrument. It proceeds on lines radically different from those adopted by Helmholtz in his classical treatment of the subject. While recognising that the elasticity of the pianoforte hammer is not a negligible factor, Kaufmann set out to simplify the mathematical analysis by ignoring its effect altogether, and treating the hammer as a particle possessing only inertia without spring. The motion of the string following the impact of the hammer is found from the initial conditions and from the functional solutions of the equation of wave-propagation on the string. On this basis he gave a rigorous treatment of two cases: (1) a particle impinging on a stretched string of infinite length, and (2) a particle impinging on the centre of a finite string, neither of which cases is of much interest from an acoustical point of view. The case of practical importance treated by him is that in which a particle impinges on the string near one end. For this case, he gave only an approximate theory from which the duration of contact, the motion of the point struck, and the form of the vibration-curves for various points of the string could be found. There can be no doubt of the importance of Kaufmann’s work, and it naturally becomes necessary to extend and revise his theory in various directions. In several respects, the theory awaits fuller development, especially as regards the harmonic analysis of the modes of vibration set up by impact, and the detailed discussion of the influence of the elasticity of the hammer and of varying velocities of impact. Apart from these points, the question arises whether the approximate method used by Kaufmann is sufficiently accurate for practical purposes, and whether it may be regarded as applicable when, as in the pianoforte, the point struck is distant one-eighth or one-ninth of the length of the string from one end. Kaufmann’s treatment is practically based on the assumption that the part of the string between the end and the point struck remains straight as long as the hammer and string remain in contact. Primâ facie , it is clear that this assumption would introduce error when the part of the string under reference is an appreciable fraction of the whole. For the effect of the impact would obviously be to excite the vibrations of this portion of the string, which continue so long as the hammer is in contact, and would also influence the mode of vibration of the string as a whole when the hammer loses contact. A mathematical theory which is not subject to this error, and which is applicable for any position of the striking point, thus seems called for.

BASIN CONFIGURATION OF A SIX-DIMENSIONAL MODEL OF AN ELECTRIC POWER SYSTEM

2002 ◽  
Vol 12 (06) ◽  
pp. 1333-1356 ◽  
Author(s):  
YOSHISUKE UEDA ◽  
HIROYUKI AMANO ◽  
RALPH H. ABRAHAM ◽  
H. BRUCE STEWART
Keyword(s):  
Power Systems ◽  
Power System ◽  
Initial Conditions ◽  
Electrical Power ◽  
Practical Importance ◽  
Intervention Strategy ◽  
Basins Of Attraction ◽  
Electric Power System ◽  
Point Of View ◽  
Electrical Power System

As part of an ongoing project on the stability of massively complex electrical power systems, we discuss the global geometric structure of contacts among the basins of attraction of a six-dimensional dynamical system. This system represents a simple model of an electrical power system involving three machines and an infinite bus. Apart from the possible occurrence of attractors representing pathological states, the contacts between the basins have a practical importance, from the point of view of the operation of a real electrical power system. With the aid of a global map of basins, one could hope to design an intervention strategy to boot the power system back into its normal state. Our method involves taking two-dimensional sections of the six-dimensional state space, and then determining the basins directly by numerical simulation from a dense grid of initial conditions. The relations among all the basins are given for a specific numerical example, that is, choosing particular values for the parameters in our model.

A regression problem

1951 ◽  
Vol 47 (2) ◽  
pp. 337-346
Author(s):  
D. V. Lindley
Keyword(s):  
Complete Solution ◽  
Practical Importance ◽  
Random Variable ◽  
Partial Solution ◽  
Point Of View ◽  
General Definition ◽  
Regression Problem ◽  
Definition Of ◽  
Regression Theory ◽  
Complete Solutions

During the Oxford Conference of the Econometric Society in September 1936, Ragnar Frisch proposed a problem in regression theory. A partial solution was found in 1938 by Miss H. V. Allen (1). A more complete solution was given by C. R. Rao (6) in 1947, and in the same year the present author (5) obtained a solution as a particular case of a more general result. These last two papers contained a flaw, and a correct solution was provided by Miss E. Fix (2). This last solution still leaves a part of the problem unanswered, and in the present paper a result of P. Lévy's (4), is used to complete the solution. At the same time further generalizations of the problem are considered and, in the cases of most practical importance, complete solutions are obtained. It is advisable, both from the point of view of rigour and simplicity of analysis, to use a general definition of the conditional expectation of a random variable. Accordingly, the paper begins with a summary of the relevant definitions. These notions were introduced by Kolmogoroff (3). It has been thought worth while giving the definitions here, in forms which are slightly different from Kolmogoroff's and seem more suitable for applications, in order to explain the notation and nomenclature used. The relevant consequences of these definitions are also stated in the form in which they are used.

The School Medical Service in Relation to Mental Defect

1921 ◽  
Vol 67 (279) ◽  
pp. 475-482
Author(s):  
G. A. Auden
Keyword(s):  
Practical Importance ◽  
Adult Life ◽  
Medical Officer ◽  
Mental Deficiency ◽  
Point Of View ◽  
Oliver Wendell Holmes ◽  
Medical Observation ◽  
Constructive Work ◽  
Points Of View ◽  
Mental Defect

When our President invited me to contribute a paper for this meeting, I understood that it was to be of the nature of a presentation of the case of the school medical officer in relation to a unification of those medical services which deal with the various aspects of mental defect. This I have attempted to do in the belief that if real constructive work is to be done, the foundations must be laid by examining the problem as it is manifested in childhood and early youth. This is comparatively easy, because not only does a very large proportion of children and young persons now come under continuous medical observation, but there is in addition the important testimony which their educational progress affords as to their mental make-up. Further, I believe that the practical solution of the question of mental deficiency from the point of view of the community at large will depend for its completeness upon early diagnosis, and upon the measures which are taken to deal with the subjects before they reach adult life. In one of his addresses, Dr. Oliver Wendell Holmes urges that in these days of specialisation we must not neglect the older theories which have yielded place to new. “The débris of broken systems and exploded dogmas form a great mound, a Monte Testaccio of shards and remnants of old vessels which once held human beliefs. If you take the trouble to climb to the top of it, you will widen your horizon.” To none is this advice more needful than to those of us who are brought into contact with mental defect and all its attendant problems. There is still so much confusion of thought, the result of changing points of view, that we do not always see clearly the end to which our efforts should be directed. This is of practical importance, because upon the standpoint from which we view the problem will depend, not only the range of our activities, but also the particular members of the community whom we hope to include therein.

scholarly journals On the inter-crystalline fracture of metals under prolonged application of stress (Preliminary paper)

1919 ◽  
Vol 96 (674) ◽  
pp. 55-68 ◽  
Keyword(s):  
Practical Importance ◽  
Point Of View ◽  
Exact Nature ◽  
Satisfactory Explanation ◽  
Fundamental Interest ◽  
Crystalline Fracture ◽  
Satisfactory Account ◽  
The Subject ◽  
Cartridge Cases ◽  
Type Of Failure

The authors have recently made a series of observations on some cases of inter-crystalline fracture in various metals, occurring as the result of the prolonged application of stress. In explanation of these phenomena they have formulated an hypothesis which appears to afford a satisfactory account of the present observations and to correlate them with other well-known phenomena whose exact nature has, however, hitherto remained obscure. In putting their observations and hypothesis on record at the present stage, the authors are well aware that much fuller experimental investigation of the whole subject is required, and they hope to carry this forward. The evidence now available, however, appears to them to justify preliminary publication, especially in view of the fundamental interest and great practical importance of the subject. The present paper relates to a group of phenomena some of which have long been known, in the case of brass, as “season cracking.” Brass articles which have been manufactured by a process of alternate cold-working and annealing—such, for instance, as cartridge-cases and other articles made by operations of cupping and drawing—sometimes exhibit a tendency, after a period which may vary from a few hours to several years, to undergo spontaneous cracking. The occurrence of this type of failure of brass has been a serious manufacturing difficulty and much study has been given to the subject; as a result, modifications of both the annealing and the drawing processes have been made, which, to a considerable extent, eliminate the trouble. A satisfactory explanation of “season cracking” has not, however, been put forward so far as the authors are aware. From the present point of view, perhaps the most interesting fact which has been observed about "season cracking” in brass is that the fracture—in those cases where its path can be traced clearly among the micro-constituents of the metal—markedly follows the inter-crystalline boundaries. An example of such a crack is illustrated, under a magnification of 100 diameters, in fig. 1, where the inter-crystalline character of the fracture can be clearly traced (Plate 1).

scholarly journals A STUDY OF THE RELATION OF TREPONEMA PALLIDUM TO LYMPHOID TISSUES IN EXPERIMENTAL SYPHILIS

1922 ◽  
Vol 35 (1) ◽  
pp. 39-62 ◽  
Author(s):  
Louise Pearce ◽  
Wade H. Brown
Keyword(s):  
Lymph Node ◽  
Lymph Nodes ◽  
Lymphoid Tissue ◽  
Practical Importance ◽  
Treponema Pallidum ◽  
Serial Passage ◽  
Point Of View ◽  
Lymphoid Tissues ◽  
Skin Nodule ◽  
Popliteal Lymph Nodes

A widespread dissemination of Treponema pallidum from a local focus of inoculation in the rabbit constantly occurs by way of the lymphatics. Spirochetes were regularly recovered from the satellite lymph nodes by animal inoculation after scrotal inoculation; they were present as early as 2 days, when no specific primary reaction was detected, and at later periods of from 5 to 61 days after inoculation. Other superficial nodes at remote sites such as the popliteals and with no syphilitic lesions in the drainage area have also been shown to harbor active organisms. Although spirochetes were found in relatively few of the lymph node emulsions, the orchitis resulting from their injection was of a rapidly progressive type with an incubation period but slightly longer than that produced by a testicular or skin nodule emulsion rich in spirochetes. It has further been shown that a syphilitic infection is sufficiently established in the rabbit body within 48 hours after scrotal inoculation so that the primary lesion is no longer essential for its maintenance. Active treponemata survive in the popliteal lymph nodes for long periods of time and have been regularly recovered from them in cases of true latency. The lymph nodes, therefore, function as reservoirs of the organisms. The ability to recover the spirochetes from lymphoid tissue through successive generations is seen in the serial passage of lymph node emulsion to testicle during an 18 months period. The persistence of spirochetes in lymphoid tissue irrespective of the presence or absence of syphilitic lesions is a characteristic and fundamental feature of syphilis of the rabbit. The existence of infection, therefore, may be demonstrated at any time by the recovery of spirochetes from the popliteal lymph nodes by animal inoculation. This fact is of great practical importance in the therapy of the infection and may be profitably utilized in determining the ultimate effect of a therapeutic agent. These experiments demonstrate that the disease is not confined to the site of local inoculation but that lymphogenous dissemination of treponemata regularly takes place, and that during the course of this process organisms become localized in the lymph nodes and exist there indefinitely irrespective of the occurrence of manifestations of disease. The intimate relation of Treponema pallidum to lymphoid tissue is an essential concept of syphilis of the rabbit, and from this point of view, the infection is primarily one of lymphoid tissue.

scholarly journals Numerical and Experimental Assessment of the Effect of Residual Stresses on the Fatigue Strength of an Aircraft Blade

2021 ◽  
Author(s):  
Arkadiusz Bednarz ◽  
Wojciech Z. Misiolek
Keyword(s):  
Residual Stresses ◽  
Practical Importance ◽  
Cyclic Hardening ◽  
Fatigue Analysis ◽  
Compressor Blade ◽  
Point Of View ◽  
Initial Stresses ◽  
Aviation Industry ◽  
Turbine Engine ◽  
Engine Maintenance

The work presents the results of numerical fatigue analysis of a turbine engine compressor blade, taking into account the values of initial stresses resulting from surface treatment - shot-peening. The values of the residual stresses were estimated experimentally using X-ray diffraction. The paper specifies the values of the residual stresses on both sides of the blade and their reduction due to the cutting through the blade - relaxation. The obtained values of the residual stresses were used as initial stresses in the numerical fatigue analysis of the damaged compressor blade, which is subjected to resonant vibrations of known amplitude. Numerical fatigue ε-N life analysis was based on the several fatigue material models: Manson’s, Mitchell’s, Baumel-Seeger’s, Muralidharan-Manson’s, Ong’s, Roessle-Fatemi’s and Median’s, and also on the three models of cyclic hardening: Manson’s, Xianxin’s, and Fatemi’s. Because of this approach, it was possible to determine the relationship between the selection of the fatigue material ε-N model and the cyclic hardening model on the results of the numerical fatigue analysis. Additionally, the calculated results were compared with the results of experimental research, which allowed for a substantive evaluation of the obtained results. These results are of great scientific and practical importance. The problem of determining the fatigue life of blades with defects operating under resonance vibrations is one of the original tasks in the field of fracture mechanics and experimental mechanics. The results obtained are of great importance in the aviation industry and can be used during engine maintenance and inspections to assess the suitability of blades with defects in terms of the needs of further work. This aspect of engineering maintenance is of great importance from the aircraft safety point of view.

scholarly journals Studying the History of the Slavic Stishnoy Prologue: New Opportunities and Prospects

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Olga Shcheglova
Keyword(s):  
Middle Ages ◽  
Critical Edition ◽  
Structural Integrity ◽  
Textual Criticism ◽  
Practical Importance ◽  
Full Scale ◽  
Point Of View ◽  
Important Stage ◽  
History Of ◽  
The Middle Ages

In this review, the author analyses the Tarnovo Edition of the Stishnoy Prologue. Texts: Lexical Index (published by Bulgarian researchers Georgi Petkov and Maria Spasova) and focuses on the structure of the publication, providing a detailed description of the parts of each volume: prologue texts, prologue poems, the lexical index, and the index of saints’ names. The review evaluates the work from the point of view of its academic contribution. The reviewer largely agrees with the authors’ point of view on the history and the study of the Stishnoy Prologue set forth in the preface to the publication. While objecting to some points, the reviewer evaluates the work highly, considering it an important stage in the process of studying the history of the Stishnoy Prologue, one of the most widespread hagiographic calendar collections of the Middle Ages. The publication of the texts of the Stishnoy Prologue, even those in just the Tarnovo edition, can be a powerful catalyst for further textual criticism and linguistic studies of the numerous Russian, Serbian, and Bulgarian copies that have survived to the present day. Ultimately, the reviewed publication can become the basis for a full-scale critical edition of the Stishnoy Prologue. The review emphasises the timeless significance of this publication for Slavic studies, its innovative character, its structural integrity, its theoretical sophistication, and the enormous practical importance of the work for Bulgarian philologists.

scholarly journals On The Issue of the Place of a Loan Commitment in the System of the Russian Law of Obligations

2018 ◽  
pp. 421-424
Keyword(s):  
Practical Importance ◽  
Civil Law ◽  
General Concept ◽  
Point Of View ◽  
Value Transfer ◽  
Scope Of Application ◽  
The Russian Federation ◽  
Russian Law ◽  
Credit Agreement ◽  
Loan Commitment

In the current Russian civil law, the loan agreement is one of the central institutions of the Russian law of obligations, since if payment for the goods and its transfer are separated by a temporary interval, there is a loan from one party to another. The same applies to the payment deferment or advance payment for the works (services). A similar situation can arise in almost any contractual construction, when one participant in a commodity turnover transfers to another some goods, performs works, renders services with the condition of returning their equivalent and, as a rule, paying remuneration. Consequently, the scope of application of the norms of paragraph 1 of Chapter 42 of the Civil Code of the Russian Federation is much broader than just a loan agreement. Loan and credit agreements refer to the "credit" concept in the economic sense. In civil law, the “credit” category is used in the narrow sense as an obligation from a credit agreement and does not cover all the above relations. Thus, the “credit” concept cannot be considered as a general concept in relation to all cases of the value transfer from one subject to another. From the point of view of the law, the “loan” category corresponds to the “credit” category in the economic sense. In this regard, the clarification of the place of borrowed obligation in the system of the Russian law of obligations is of great theoretical and practical importance.

scholarly journals Ethnic Stereotypes in Intercultural Communication: Psychological and Semantic Aspects

2019 ◽  
Vol 10 (4) ◽  
pp. 977-989
Author(s):  
Alexey L. Novikov ◽  
Irina A. Novikova
Keyword(s):  
Intercultural Communication ◽  
Intercultural Competence ◽  
Empirical Studies ◽  
Practical Importance ◽  
Modern Society ◽  
Semantic Differential ◽  
Point Of View ◽  
Ethnic Stereotypes ◽  
The Face ◽  
The One

Currently, ethnic stereotypes are considered as phenomena that mediate the processes of intercultural perception, dialogue and interaction. This fact determines the relevance of it comprehensive interdisciplinary study by different sciences (sociology, political science, psychology, linguistics, etc.). In this article, ethnic stereotypes are analyzed, firstly, at the psychological level (types, functions, structure), and secondly, at the psycholinguistic and psychosemantic levels (from the point of view of the rationale for it diagnosis with using the semantic differential). The possibilities of the semantic differential for studying the content, consistency, direction and intensity of social stereotypes in general, as well as the method modifications for diagnosis ethnic stereotypes, are examined. The heuristic potential of semantic differential for diagnosing ethnic stereotypes as phenomena, on the one hand, reflecting various aspects of intercultural perception and dialogue, and, on the other hand, directly affecting the intercultural interaction, is shown on the example of empirical studies on ethnic stereotypes in the intercultural communication context. The results of ethnic stereotypes studies are of high practical importance for the development of programs for increase intercultural competence, which are in demand in various areas of modern society in the face of e globalization and the growth of intercultural contacts (education, business, tourism, etc.).

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