Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 766
Filtrar
2.
Stud Hist Philos Biol Biomed Sci ; 78: 101181, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31257101

RESUMO

D'Arcy Wentworth Thompson's "Science of Form" - the explanation of biological development and morphology through physical forces and mathematical laws - has traditionally been viewed as an idiosyncratic, even heretical, episode in the history of evolutionary biology. Yet recent scholarship has sought to overturn this view by demonstrating that Thompson was active in contemporary scientific networks. This paper argues that a key influence upon Thompson's seminal work, On Growth and Form (1917), may be far more practical, and lie closer to home, than previously realised: experimental demonstrations of basic concepts in physics. Harnessing previously unpublished archival sources, this paper traces Thompson's correspondence with Charles Darling, Arthur Worthington and Cecil Warburton. In these exchanges, Thompson described his own experiments, or requested that experiments be conducted on his behalf. This correspondence, and its subsequent inclusion in the first edition of On Growth and Form, revises our current picture of Thompson from that of an abstract thinker to keen experimentalist. Moreover, his contact with physicists indicates that simple experiments enabled extensive crosstalk between early twentieth century physics and biology.


Assuntos
Evolução Biológica , Biologia do Desenvolvimento/história , Física/história , Animais , História do Século XX , Morfogênese
3.
Ann Sci ; 76(1): 17-57, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30829119

RESUMO

This paper investigates the relationship between Helmholtz's formulation of the principle of the conservation of force and the two principles well known in rational mechanics as the principle of vis viva and the principle of the conservation of vis viva. An examination of the relevant literature from Leibniz to Duhamel reveals both Helmholtz's indebtedness to that tradition and his creative refashioning of it as he endeavoured to craft an argument that would both prohibit the construction of a perpetuum mobile and the efficacy of a supposed vital force and demonstrate the necessity of an ontology of mass points subject to attractive and repulsive central forces depending solely on distance.


Assuntos
Fenômenos Físicos , Física/história , Alemanha , História do Século XIX , Fenômenos Mecânicos
4.
Ann Sci ; 76(1): 1-16, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30829559

RESUMO

The worksheets that presumably contained Newton's early development of the fundamental concepts in his Principia have been lost. A plausible reconstruction of this development is presented based on Newton's exchange of letters with Robert Hooke in 1679, with Edmund Halley in 1686, and on some clues in the diagram associated with Proposition 1 in Book 1 of the Principia that have been ignored in the past. A graphical construction associated with this proposition leads to a rapidly convergent method to obtain orbits for central forces, which elucidates how Newton may have have been led to formulate some of his most fundamental propositions in the Principia.


Assuntos
Correspondência como Assunto/história , Manuscritos como Assunto/história , Matemática/história , Física/história , História do Século XVII , Reino Unido
5.
Ann Sci ; 76(1): 58-86, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30794077

RESUMO

The torsion balance, an instrument that was first developed to demonstrate the high precision of physical science in the laboratory became a different sort of demonstration instrument in its brief vogue in the 1920s. This article considers intersecting stories of acquiring and testing the torsion balance as a field instrument in Canada, Britain and Australia. It examines the purchasing trip and fieldwork of A. H. Miller of the Dominion Observatory in 1928-1931, testing conducted by the British Geological Survey in 1926-1930, and finally the Imperial Geophysical Experimental Survey of 1928-1930 in Australia. These different stories produce a kind of collective biography, illustrating well the variety of material and textual records that accrete around instruments, especially expensive ones. But the trials and travels of the torsion balance also point to large themes. By comparing the different ways an instrument becomes valuable, and to whom, these micro-histories reveal significant features of the developing identity of geophysics. They also show the interaction of different forms of scientific internationalism in the inter-war period.


Assuntos
Precisão da Medição Dimensional , Física/história , Torção Mecânica , Austrália , Canadá , História do Século XX , Reino Unido
9.
BMC Biol ; 16(1): 130, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30382844

RESUMO

Kerwyn Casey ("KC") Huang is an Associate Professor at Stanford University, studying the physical nature of biological systems and the underpinnings of fundamental processes such as cell shape determination, cell division, and intracellular and microbial community organization. In this interview, KC discusses how the ability to pursue insights at scales from molecules to cellular communities can shed new light on longstanding questions, the necessity for new tools in exploring the microbiome, how to create an empowering lab environment, and why integrating chemistry with physics and biology can bring us closer to asking the right questions.


Assuntos
Biologia/história , Química/história , Microbiota , Física/história , California , História do Século XXI
12.
Ann Sci ; 75(3): 234-254, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30022714

RESUMO

During the 1970s, widespread scientific interest in the risks of climate change prompted John A. Eddy (1931-2009), an astrophysicist with the National Center for Atmospheric Research in Boulder, CO, to investigate whether sunspots could be used to predict future climate changes. Methodologically, Eddy's investigations were uniquely historical in nature. By interrogating old manuscripts of solar observations since the early seventeenth century, he identified what appeared to be a correlation between the so-called Maunder Minimum - a virtual cessation of sunspots between 1645 and 1715 - and severely cold temperatures during the Little Ice Age. While he could not identify the physical mechanisms that governed solar-climate relationships, this historical episode fostered his curiosity. Fortuitously, Eddy's solar-climate research coincided with efforts to use satellites to monitor and record variations in solar energy output, which in context constituted a significant development in managing environmental and technological risk. But using the Maunder Minimum to advance the frontiers of knowledge about solar-terrestrial relationships was not Eddy's only - or even primary - motivation. In the mid-1840s, German astronomer Heinrich Schwabe (1789-1875) discovered what appeared to be a decadal sunspot cycle, the existence of which inspired generations of astrophysicists to more precisely estimate its length as well as determine its underlying causes. Eddy, however, came to believe that the astronomical community failed to consider the implications of subsequent evidence suggesting that Schwabe's solar cycle was not an enduring characteristic of the sun. Instead, he reasoned that evidence offered by nineteenth-century European astronomers Gustav Sporer and Edward Maunder in the 1880s and 1890s had been entirely overlooked. But rather than arguing that their evidence was overlooked in error, Eddy identified what he cast as a conspiracy of wilful ignorance on the part of a staid and conservative astronomical community. By utilizing Eddy's private hand-written notes as they appeared in undergraduate lectures, public speeches and academic talks, as well as his appreciation for the seminal views of sociologist of science Thomas Kuhn, I show that Eddy sought to rectify this injustice by proposing a contrasting vision of science as an interdisciplinary, collaborative and creative process of exploring the ignored areas between scientific disciplines.


Assuntos
Astronomia/história , Mudança Climática/história , Física/história , Atividade Solar , Fenômenos Astronômicos , História do Século XVII , História do Século XVIII , História do Século XIX , História do Século XX , Estados Unidos
14.
Trends Cancer ; 4(4): e1-e6, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29656775

RESUMO

Nastaran Zahir is Associate Director of the Physical Sciences - Oncology Network in the Division of Cancer Biology at the National Cancer Institute. Dr. Zahir coordinates cross-cutting efforts to integrate physical sciences perspectives with cancer research by fostering transdisciplinary research collaborations, supporting education and outreach programs, and promoting resources for data sharing and biospecimen standards.


Assuntos
Pesquisa Biomédica/métodos , Oncologia/métodos , National Cancer Institute (U.S.)/economia , Neoplasias/etiologia , Física/métodos , Pesquisa Biomédica/economia , Pesquisa Biomédica/história , Pesquisa Biomédica/tendências , Financiamento de Capital , História do Século XX , História do Século XXI , Humanos , Oncologia/economia , Oncologia/história , Oncologia/tendências , National Cancer Institute (U.S.)/organização & administração , National Cancer Institute (U.S.)/tendências , Neoplasias/terapia , Física/economia , Física/história , Física/tendências , Pesquisadores , Microambiente Tumoral , Estados Unidos
16.
J Biol Chem ; 293(10): 3470-3476, 2018 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-29523692

RESUMO

My scientific career has taken me from chemistry, via theoretical physics and bioinformatics, to molecular biology and even structural biology. Along the way, serendipity led me to work on problems such as the identification of signal peptides that direct protein trafficking, membrane protein biogenesis, and cotranslational protein folding. I've had some great collaborations that came about because of a stray conversation or from following up on an interesting paper. And I've had the good fortune to be asked to sit on the Nobel Committee for Chemistry, where I am constantly reminded of the amazing pace and often intricate history of scientific discovery. Could I have planned this? No way! I just went with the flow ….


Assuntos
Engenharia Química/história , Biologia Computacional/história , Proteínas de Membrana/história , Modelos Moleculares , Biologia Molecular/história , Física/história , Animais , História do Século XX , História do Século XXI , Humanos , Bicamadas Lipídicas/química , Bicamadas Lipídicas/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Cidade de Nova Iorque , Dobramento de Proteína , Sinais Direcionadores de Proteínas , Transdução de Sinais , Suécia
17.
Phys Med ; 47: 139-143, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29576466

RESUMO

In London, November 1915, a telegram was received at the home of William Henry Bragg from the secretary of the Academy of Science in Stockholm announcing the award of the Nobel Prize in Physics for "the analysis of crystal structures by means of X-rays". A second similar telegram was addressed to his 25 year old son William Lawrence Bragg (Jenkin, 2008). This article commemorates the centenary of that event and the unveiling of a bust of Sir William Bragg alongside that of his son, Sir Lawrence Bragg, on North Terrace in Adelaide where he spent 23 years of his early career.


Assuntos
Prêmio Nobel , Física/história , Austrália , História do Século XX , História do Século XXI
18.
Ann Sci ; 75(1): 1-20, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29417878

RESUMO

This paper provides an account of Chinese translations of Newton's Principia produced over the past century and a half within the larger context of the dissemination of Newtonian philosophy in China. Given its fundamental importance in the history of science, the Principia, originally penned in Latin, has been translated into a number of other languages. While in all these languages no more than two full translations have appeared, as many as four complete versions in Chinese have been produced since the 1850s, when first attempts were made to translate the Principia in late imperial China. They include a 1931 version in semi-classical Chinese completed during the Republican era and three rival versions in modern Chinese published in contemporary China. This rich history of translating the Principia into Chinese, which remains little known to scholars in the West, is for the first time reconstructed and presented in English. This account is based on a meticulous scrutiny of manuscripts, historical records, secondary literature and interviews with some of the contemporary translators. It demonstrates that Chinese translation of the Principia is a complex process that involves scientific traditions, linguistic peculiarities, translators' subjectivity, readers' expectations and even the role of the market.


Assuntos
Astronomia/história , Matemática/história , Física/história , Traduções , China , História do Século XVIII , História do Século XIX , História do Século XX , História do Século XXI , Linguagem
20.
Acta Ophthalmol ; 96(3): 314-320, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-28772001

RESUMO

Hermann von Helmholtz (1821-1894) was one of the most important scientists of the nineteenth century in optics and ophthalmology. One of his significant contributions in the field of vision sciences was the invention of the ophthalmometer in 1850, which was the precursor of the keratometers still used in clinical practice today. However, this development tends to be little recognized, and to be overshadowed by others of the achievements of this singular scientist. This review describes the historical setting behind the von Helmholtz's ophthalmometer and its mechanism. We also describe the modifications that were later made to the design. We report on our experience measuring a living human cornea with one of the last surviving devices in the world. The ophthalmometer by von Helmholtz marked the beginning of an era in the ophthalmology of the late nineteenth century, and although its original design was not broadly used in the clinical practice, and later abandoned, it opened the way for the development of practical systems very similar to the ones that we use even today.


Assuntos
Técnicas de Diagnóstico Oftalmológico/história , Desenho de Equipamento/história , Física/história , Técnicas de Diagnóstico Oftalmológico/instrumentação , Alemanha , História do Século XIX , Humanos , Oftalmologia/história , Óptica e Fotônica
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA