On the laws of polarization and double refraction in regularly crystal­lized bodies. By David Brewster, LL. D. F. R. S. and Edin. In a letter to the Right Hon. Sir Joseph Banks, Bart. G. C. B. P. R. S

1833 ◽  
Vol 2 ◽  
pp. 92-93
Keyword(s):  
Optical Properties ◽  
General Principle ◽  
General View ◽  
Double Refraction ◽  
Primitive Form ◽  
General Law ◽  
Combined Action ◽  
The Right ◽  
Polarization Of Light ◽  
High Degree

In the different inquiries which the author has already laid before this Society, his attention was often directed to the phenomena of regular crystals; but he only lately succeeded in reducing under a general principle all those complex appearances which result from the combined action of more than one axis of double refraction. In this paper Dr. Brewster gives a general view of the present state of our knowledge respecting the double refraction and polarization of light, and afterwards traces the steps which led him to the discovery of the general law. He began his researches by the examination of 165 crystals, in 145 of which he discovered the property of double refraction. In 80 he was able to ascertain whether they had one or more axes; and by examining the tints which they exhibited at va­rious angular distances from the axes, whence the forces emanate, he has been led to a general principle, which embraces all the phenomena and extends to the most complex as well as to the most simple de­velopment of the polarizing forces. This general principle, says Dr. Brewster, is in no respect an empyrical expression of the facts which it represents, nor is it supported by any empyrical data. Founded on the principles of mechanics, it is a law rigorously physical, by which we are enabled to calculate all the tints of the coloured rings, and all the phenomena of double refraction, with as much accuracy as we can compute the motions of the heavenly bodies. The faculty of depolarization, explained by the author in a former paper, has been considered as sufficient indication of two separate images; and upon this principle it has been stated that all crystals are doubly refractive whose primitive form is neither the cube nor the regular octohedron: but this is incorrect; for some of these crystals possess a doubly refracting structure in a high degree. Ad­mitting the statement, however, it could not have been used as a rule for determining whether a crystal refracts doubly or singly; for it is more difficult to detect the primitive form than to examine the optical properties. Tungstate of lime, for instance, would have been reckoned a crystal without double refraction, when Haüy believed its primitive form to be the cube, although it is highly doubly refractive.

scholarly journals XIII. On the laws of polarisation and double refraction in regularly crystallized bodies. By David Brewster, LL. D. F. R. S. Lond. and Edin. In a letter to the Right Hon. Sir Joseph Banks, Bart. G. C. B. P. R. S

1818 ◽  
Vol 108 ◽  
pp. 199-273 ◽  
Keyword(s):  
Present State ◽  
General Principle ◽  
Royal Society ◽  
Physical Science ◽  
Double Refraction ◽  
General Law ◽  
Relative Value ◽  
Combined Action ◽  
The Subject ◽  
The Right

Dear sir, In the different memoirs which you have done me the honour of submitting to the Royal Society, I have considered principally those branches of the polarisation of light which relate to the superficial action, or the superinduced properties of uncrystallized bodies. In the course of these enquiries, my attention was frequently directed to the phenomena of regular crystals; but from the difficulty of procuring proper specimens, and the extreme perplexity of the subject, it was not till lately that I succeeded in reducing under a general principle all the complex appearances which result from the combined action of more than one axis of double refraction. Before I proceed to trace the steps which have conducted me to this general law, I must entreat the indulgence of the Society, while I attempt to give a brief and rapid view of the present state of our knowledge respecting the laws of double refraction. They will thus be able to appreciate more correctly the relative value of those successive generalisations by which this subject has been raised to one of the most interesting departments of physical science.

scholarly journals III. Experiments on the depolarisation of light as exhibited by various mineral, animal, and vegetable bodies, with a reference of the phenomena to the general principles of polarisation. By David Brewster, LL. D. F. R. S. Edin and F. S. A. Edin. In a letter addressed to the Right Hon. Sir Joseph Banks, Bart. K. B. P. R. S

1815 ◽  
Vol 105 ◽  
pp. 29-53 ◽  
Keyword(s):  
Optical Properties ◽  
General Principle ◽  
Gum Arabic ◽  
Natural Philosopher ◽  
Double Refraction ◽  
Short Account ◽  
Vegetable Products ◽  
Direct Experiment ◽  
The Right ◽  
Iceland Spar

Dear Sir Towards the end of the year 1812, when I was engaged in examining the light transmitted through diaphanous bodies, I discovered the property which many of them possessed of depolarising the rays of light, or of depriving them of the po­larity which they had received, either by reflection from the surface of a transparent body, or by transmission through a plate of agate. A short account of these experiments, which were exhibited to many of my friends in Edinburgh, was soon afterwards published in my treatise on new philosophical instruments. As this singular property was possessed by numerous sub­stances that exhibited no marks of double refraction, and even by animal and vegetable products, such as horn, tortoise­ shell, and gum Arabic, it appeared necessary to distinguish it by a new name, and to refer it to a species of crystalliza­tion different from that of doubly refracting crystals. The circumstance, however, of agate and Iceland spar possessing the faculty both of polarising and depolarising light, and the constant relation in the position of the axes which regulated these apparently opposite actions, induced me to think that the two classes of phenomena had the same origin. This opinion was afterwards strengthened by an experiment with a bundle of glass plates, in which light was depolarised by polarising it in a new plane; but in applying the principle to other phenomena, I was baffled in every attempt to generalise them. By extending, however, and varying the experiments; by examining the optical properties of every substance which I could command, and by comparing their structure with the phenomena which they exhibited, I have been led to the general principle to which they all belong, and to a series of results which, from their very nature, could not easily have been established by direct experiment. These conclusions, independently of their optical consequences, are peculiarly in­teresting to the chemist and the natural philosopher, by dis­closing the structure of organised substances, and exhibiting new relations among the bodies of the animal, the vegetable, and the mineral kingdoms.

scholarly journals VI. On certain peculiarities in the double refraction and absorption of light exhi­bited in the oxalate of chromium and potash

1835 ◽  
Vol 125 ◽  
pp. 91-93
Keyword(s):  
Aqueous Solution ◽  
Optical Properties ◽  
Solid State ◽  
The State ◽  
Sharp Edge ◽  
General View ◽  
Broad Face ◽  
Double Refraction ◽  
Short Notice ◽  
Absorption Of Light

This remarkable salt was put into my hands about the end of the year 1832, by Dr. William Gregory, of Edinburgh, to whom I have been indebted for much kind assistance in carrying on my inquiries respecting the action of coloured bodies in ab­sorbing definite rays of the spectrum. A very brief examination of its optical properties was sufficient to indicate its more obvious peculiarities, and a short notice of these was published at the time. Having received, however, from Dr. Gregory a very fine group of well formed crystals, and having had an opportunity in the spring of 1833 of observing their action upon the spectrum, both in their solid state and in the state of aqueous solution, I am now able to present to the Society a general view of the results which I obtained. The oxalate of chromium and potash occurs in flat, irregular, six-sided prisms. The two broadest faces are inclined to each other like the faces of a wedge, whose sharp edge is the summit of the crystal. These faces are considerably rounded, being pa­rallel near the base, and inclined to each other about three degrees at the apex of the prism. The incidence of the broad faces upon the adjacent faces of the prism is about 140°, and therefore these faces are inclined to one another at an angle of 180° — 148° × 2 = 64°. The crystal is terminated by four minute planes equally inclined to the broad face and the axis of the prism, but two of these faces often disappear, and the crystal terminates in an oblique edge in place of a triangular apex.

scholarly journals Challenges and Controversies in the Genetic Diagnosis of Hereditary Spastic Paraplegia

2021 ◽  
Vol 21 (4) ◽  
Author(s):  
Lydia Saputra ◽  
Kishore Raj Kumar
Keyword(s):  
Genetic Diagnosis ◽  
Spastic Paraplegia ◽  
Limb Weakness ◽  
Hereditary Spastic Paraplegias ◽  
Gene Testing ◽  
Testing Strategies ◽  
Whole Exome ◽  
The Right ◽  
Gene Panels ◽  
High Degree

Abstract Purpose of Review The hereditary spastic paraplegias (HSPs) are a group of disorders characterised by progressive lower limb weakness and spasticity. We address the challenges and controversies involved in the genetic diagnosis of HSP. Recent Findings There is a large and rapidly expanding list of genes implicated in HSP, making it difficult to keep gene testing panels updated. There is also a high degree of phenotypic overlap between HSP and other disorders, leading to problems in choosing the right panel to analyse. We discuss genetic testing strategies for overcoming these diagnostic hurdles, including the use of targeted sequencing gene panels, whole-exome sequencing and whole-genome sequencing. Personalised treatments for HSP are on the horizon, and a genetic diagnosis may hold the key to access these treatments. Summary Developing strategies to overcome the challenges and controversies in HSP may hold the key to a rapid and accurate genetic diagnosis.

scholarly journals III. Investigations of the specific heat of solid bodies

1865 ◽  
Vol 155 ◽  
pp. 71-202 ◽  
Keyword(s):  
Specific Heat ◽  
Thermal Action ◽  
General View ◽  
Specific Heats ◽  
General Law ◽  
Different Temperatures ◽  
The Times ◽  
The Individual ◽  
Solid Bodies

I. About the year 1780 it was distinctly proved that the same weights of different bodies require unequal quantities of heat to raise them through the same temperature, or on cooling through the same number of thermometric degrees, give out unequal quantities of heat. It was recognized that for different bodies the unequal quantities of heat, by which the same weights of different bodies are heated through the same range, must be determined as special constants, and considered as characteristic of the individual bodies. This newly discovered property of bodies Wilke designated as their specific heat , while Crawford described it as the comparative heat, or as the capacity of bodies for heat . I will not enter upon the earliest investigations of Black, Irvine, Crawford, and Wilke, with reference to which it may merely be mentioned that they depend essentially on the thermal action produced when bodies of different temperatures are mixed, and that Irvine appears to have been the first to state definitely and correctly in what manner this thermal action (that is, the temperature resulting from the mixture) depends on the original temperature, the weights, and the specific heats of the bodies used for the mixture. Lavoisier and Laplace soon introduced the use of the ice-calorimeter as a method for determining the specific heat of bodies; and J. T. Mayer showed subsequently that this determination can be based on the observation of the times in which different bodies placed under comparable conditions cool to the same extent by radiation. The knowledge of the specific heats of solid and liquid bodies gained during the last century, and in the first sixteen years of the present one, by these various methods, may be left unmentioned. The individual determinations then made were not so accurate that they could be compared with the present ones, nor was any general conclusion drawn in reference to the specific heats of the various bodies. 2. Dulong and Petit’s investigations, the publication of which commenced in 1818, brought into the field more accurate determinations, and a general law. The investigations of the relations between the specific heats of the elements and their atomic weights date from this time, and were afterwards followed by similar investigations into the relations of the specific heats of compound bodies to their composition. In order to give a general view of the results of these investigations, it is desirable to present, for the elements mentioned in the sequel, a synopsis of the atomic weights assumed at different times, and of certain numbers which stand in the closest connexion with these atomic weights.

The Right to Repair Goods in the Era of Digitalization and Globalization

2021 ◽  
Vol 16 (12) ◽  
pp. 45-52
Author(s):  
P. L. Likhter
Keyword(s):  
Circular Economy ◽  
Medical Equipment ◽  
Environmental Safety ◽  
Spare Parts ◽  
Service Organizations ◽  
Warranty Period ◽  
Market Participants ◽  
The Right ◽  
High Degree

Today, large companies are increasingly using controversial strategies related to the violation of the buyer’s rights to repair the goods both during and after the expiration of the warranty period. This is primarily manifested in the restriction of access to the necessary information on the product repairing, hindering the work of independent service organizations, intentional complication of parts during their design, unreasonably high degree of integration of units, lack of a sufficient number of spare parts on the market, etc. As a rule, such actions distort the principles of integrity and transparency, which, in turn, entails risks to consumer and environmental safety. This issue is of particular relevance in the context of the COVID-19 pandemic, when sellers of medical equipment restrict the possibility of its restoration by independent specialists, and also prevent the distribution of the necessary software. Based on the results of the work, it is concluded that it is advisable to establish boundaries for the conduct of market participants to stimulate the production of durable and maintainable goods in order to transit to a circular economy.

scholarly journals Origin, Traject and Distribution of Renal Arteries (Arteriae renalis) in Chinchilla lanigera

2018 ◽  
Vol 75 (1) ◽  
pp. 129
Author(s):  
Cristian MARTONOS ◽  
Cristian DEZDROBITU ◽  
Florin STAN ◽  
Aurel DAMIAN ◽  
Alexandru GUDEA
Keyword(s):  
Renal Artery ◽  
Renal Arteries ◽  
Left Renal Artery ◽  
Lateral Part ◽  
Formaldehyde Solution ◽  
Anatomical Dissection ◽  
The Right ◽  
High Degree ◽  
Aorta Abdominalis ◽  
Degree Of Similarity

For the present study a number of 5 female chinchilla carcasses were used. The animals were slaughtered for commercial purpuses (fur). The anatomical dissection started with the identification of the aorta (Aorta abdominalis). The next step was the intra-arterial injection of a colouring substance. The carcasses was fixed in the formaldehyde solution and subsequently the renal arteries were dissected. The first renal artery was the right renal artery (Arteria renalis dextra) and, at 0,5 cm caudally, the left renal artery (Arteria renalis sinister) arose . The origin of those arteries were disposed on the lateral part of the abdominal aorta.The origin, traject and distribution of renal arteries on the studied species have a high degree of similarity with the literature dates described for leporids.

scholarly journals Subjective Experience of Speech Depending on the Acoustic Treatment in an Ordinary Room

2021 ◽  
Vol 18 (23) ◽  
pp. 12274
Author(s):  
Emma Arvidsson ◽  
Erling Nilsson ◽  
Delphine Bard-Hagberg ◽  
Ola J. I. Karlsson
Keyword(s):  
Speech Perception ◽  
Subjective Experience ◽  
Sound Quality ◽  
Reverberation Time ◽  
Acoustic Environment ◽  
Acoustic Environments ◽  
The Right ◽  
Acoustic Treatment ◽  
High Degree ◽  
Speech Clarity

In environments such as classrooms and offices, complex tasks are performed. A satisfactory acoustic environment is critical for the performance of such tasks. To ensure a good acoustic environment, the right acoustic treatment must be used. The relation between different room acoustic treatments and how they affect speech perception in these types of rooms is not yet fully understood. In this study, speech perception was evaluated for three different configurations using absorbers and diffusers. Twenty-nine participants reported on their subjective experience of speech in respect of different configurations in different positions in a room. They judged sound quality and attributes related to speech perception. In addition, the jury members ranked the different acoustic environments. The subjective experience was related to the different room acoustic treatments and the room acoustic parameters of speech clarity, reverberation time and sound strength. It was found that people, on average, rated treatments with a high degree of absorption as best. This configuration had the highest speech clarity value and lowest values for reverberation time and sound strength. The perceived sound quality could be correlated to speech clarity, while attributes related to speech perception had the strongest association with reverberation time.

On the Evolution of the Northwest Coast Indian Communities (A Soviet-American Discussion and Its Sequel)

2021 ◽  
Vol 17 (51) ◽  
pp. 141-172
Author(s):  
Igor V. Kuznetsov ◽  
Keyword(s):  
The United States ◽  
Northwest Coast ◽  
Franz Boas ◽  
Class Theory ◽  
High Profile ◽  
Public Campaign ◽  
Political Views ◽  
The Social ◽  
The Right ◽  
High Degree

The article is devoted to the discussion among Soviet and U.S. scholars about the social organization of the Indians of the Northwest Coast of North America. In the classic textbooks on “primitive history”, the Indians of this region—the Tlingit, Haida, Tsimshian and Kwakwaka’wakw (Kwakiutl)—are mentioned as examples of a high degree of social differentiation based on a (fishing and maritime) foraging economy and even as instances of pre-state structures. The proposed concepts were, to varying degrees, determined by external factors: personal political views, high-profile events, or government pressure. In 1897, Franz Boas recognized the potlatch ceremony—demonstrative exchanges of gifts and destructions of surplus, a practice exotic to Europeans—as an analogue of a credit operation. This interpretation, not empirically substantiated, originated from a public campaign to legalize potlatch. In the 1930s, Julia Averkieva, a Soviet intern of Boas, interpreted some fragments of her mentor’s teaching through the Marxist class theory framework, shifting the emphasis from potlatch to slavery: the Northwest Indians allegedly began the transition to slavery from a classless system in which the potlatch was an instrument for preserving property equality. Averkieva’s interpretation became canonical in the USSR, whilst also finding some reception outside the socialist camp. In the United States, relativistic cultural interpretations dominated; domestic evolutionary Marxist models were marginal and were not rooted in the Soviet tradition. However, after the collapse of the USSR, they also became part of the research mainstream, being criticized not only from the right, but also from the left—from anarchist viewpoints.

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